Questions

Three tips for encouraging problems: Recognizing problem, facing problem, and solving problem.
Knowledge is the key to let these processes go well.
We have listed below for frequently encountered problems.
We also share what we know with you in our newsletters that is called "Knowledge Communication".
Hoping our efforts will be helpful to you.

  • Problems of general measures
    Protection of the skin
    Should prevent skin and light from hardenning the resin to contact directly, so as not to cause the skin inflammation. Use the rubber glove of the thick quality to totally block the skin and keep in touch, effective protection hands. Consider only hardenning the resin erosion and permeability to the glove material while choosing the glove. Result that the PE glove that generally common PVC emulsion glove and surface are porous was not protected for a long time. According to studying, the material of the rubber glove hardens main compositions of the resin to the light with Nitrile Rubber and Butyl Rubber --It is best to press one gram of shelter results with single strength. The sweat liquid of the human body is apt to cause the skin inflammation too. The rubber glove of the cotton intermediate layer can be reduced and arranged the sweat, protect the skin. Much skin care products can protect the skin, the ones that avoided chemical raw materials were infected with. Control the products which arrange the sweat too on the market. It is very valid that it is used that it is large, apt to cause the season of the skin inflammation in the humidity. Work in the clean long sleeves trousers, avoid only hardenning the resin and keeping in touch with the skin. Working had better be worn clean work clothes each time. Some cases show the soiled clothes will cause the skin inflammation too. The clothes should be changed immediately when being infected with chemical raw materials, and wash clean. Deal with and should work in such airtight shoes as the safe shoes of very beginning of steel or the rubber material,etc. while only hardenning the resin in a large amount. Plimsolls, soft leather shoes ,etc. may have permeated products,not and the unsuitable wear. When the shoes are permeated by products pollution, must abandon at once, the bubble arises in order to avoid the foot by the stimulus of the medicines.

    Protection of eyes
    Eyes are extremely fragile, expose in the external organ most frequently. Protecting eyes, it is the most basic protection to use the goggles to equip. Must be worn while contacting and only hardenning the resin. The mirror reason part of the goggles will often be infected with the resin, and then it is allergic to cause, should keep a lookout carefully. The chemical smog will be affixed to contact lenses, stimulate eyes. So it is unsuitable to wear the work of the contact lenses. While working under the strong light, must wear the dark color (brown) Goggles about protect eyes. The dark lens can reduce the intensity of light, the brown lens can be strained except that blinding ultraviolet ray and blue are smooth; So defend the strong mere result best with the goggles of the dark brown lens.

    Protection of the respiratory track
    Liquid material (here inside including only hardenning the resin) How much will have volatility. Suck volatilizing the gas and may cause of chemistry dizzy and having sore throat Wait for the uncomfortable symptom. The light of low volatility relatively has no taste to harden the resin; But heat will happen when the license is only hardenned in the resin, may still produce the stink. Some harden resin to spray form operate, volatilize control of material even more important or in high temperature only. The method to solve foul smell completely is to set up the system of smoking to exhaust, from having the glue to shining Wait for the route to all need. Exhaust equipment and not so good as costliness of imagination, so long as a few funds can win improvement by a wide margin usually. The equipment of the personal protection is good with NIOSH/MSHA protecting device of breath up to the standards. The mask taken for personal protection is suitable for and used in the occasion of short time, low stink; Its activated carbon pot should be changed regularly. Taking cotton cloth, chemical fibre as material and dustproof can't isolate the harmful gas with the gauze mask. No matter what a good shelter mask performance can can't be replaced and ventilated the good homework environment.

    Protection of the personal hygiene
    When each job finishes, it is very important to take a shower and change the clothes, the skin surface that it will be polluted is washed clean immediately, and remove the polluter completely.

    Clean protection of the house
    Avoiding the skin inflammation, it is a very important part to be clean at home. At home clean to make well, person who suffer from, skin of inflammation can increase. In a lot of examples, allergic to can appear immediately, is it can perceive pollutant the infeted to cause. Want it when keep in touch repeatedly for a long time, the skin will just begin to be injured. It is clean to strengthen the house, can prevent contacting the chance of the polluter repeatedly.
  • Problems of first-aid measures
    First aid that the skin contacts
    The clothes polluted are taken off, wash the skin surface clean completely with the soap. If the light which is infected with to the high viscosity hardens the resin, the sanitizer which uses the high thickness can be cleaned comparatively fast. Secondly, can guarantee in 15 minutes to steep the skin raw materials are totally cleaned to wash with the a little warm water. Don't polish the skin with the organic solvent. Though solvent can getting rid of fast resin,also can letting resin not lasted skin fast. Recent finding: Daub the hormone milk lotion of one pair of renal glands on the skin immediately when dipping in to chemical raw materials, can prevent bubble from occurring effectively. If the skin still turns red or irritated after washing the resin off, the symptom with the skin inflammation that this kind of ointment can also lower and bubble effectively. Once the bubble arises, should send and cure to make a diagnosis and give treatment and avoid infecting.

    First aid that eyes contact
    Wash for 20-30 minutes with clean warm water immediately, send off and cure and make a diagnosis and give treatment immediately.

    First aid that the ozone sucks
    If the different form takes place because of sucking foul smell while operating, must move to the place with fresh air immediately, implement artificial respiration or oxygen, and send and cure treating immediately.

    Eat the first aid of the resin by mistake
    The patient can drink 0.57 liters when eating the resin by mistake and combining consciousness and waking up (1 pint) Water not warm it dilutes to be chemical material,and send off not curing immediately. Is it is it is it is it carry out to come by doctor to want, is it is it may cause than poison dangerous lung injure to spit to urge without permission to spit to urge.
  • Notice
    The accident endangering
    Heavy handled polyreaction. Harden resin is it chain to react by a lot of simple member only but huge member that become. Will emit very great heat during the process of reacting and getting together. Whole bottle (barrel) It is a very dangerous thing that the light put hardens the resin and exposes or heats, because the polyreaction that the accident causes is very difficult to control, violent exothermic may cause the becoming type of the container, melt down; The products break out and solve, drag and give vent to anger the body; Even cause resin spontaneous combustion.

    Danger of the fire
    It belongs to more flammable things to only harden the resin. Raw materials gas produced to burn can cause irritated, there is danger of sucking nature. The temperature of the flame will destroy the polymer, products of container know splitting decomposition destroy, the intensity of a fire may spread too.

    The urgent one handling
    When the light hardens the resin accident and generates heat, it is to defend the method to make calamity effectively to soak in water and cool rapidly. Situation when allowing, is it is it lower the temperature or move container to place a bit let it cool continuously far to ventilate to turn on. If when the fire takes place, use and train due protection to equip at ordinary times: Breathe the utensil, whole body suit, face guard, security shoes and glove. It is not the first-aid personnel that withdraw, will keep the air circulating. Put out a fire from the safe distance with the universe type chemical foam or carbon dioxide at the time of the fire.

    Procedure that abandons
    The container that used has remaining resin. Must take gloves to protect, put to the place far away from light source, heat source while clearing the empty container. Usually according to the classification of RCRA, it is not a dangerous offal to only harden the resin. Can abandon on the appointed rubbish field or incinerate the factory according to the regulation of offal treatment.

    Store
    Harden resin must is it is it shut or make products not to break out Yi solved to assemble to store only. 1.Store it in the place far away from sunshine. 2.Store it in the shady and cool place to ventilate. 3.Don't wanton change resin packaging. 4.Choose the proper resin container at the time of partial shipment. (For example: PE, PP plastic barrel, stainless steel barrel, the carbon steel barrel of the resin coating, ,or glass ware) 5.Avoiding keeping in touch with such metal as the copper, iron,etc., they will cause and get together. 6.Don't smoke vacuum treatment of the resin. 7.Don't be filled with the nitrogen or the gas not containing oxygen in the resin is packed. 8.Don't fill-up the resin on the container. Must keep space in the container, offer and suppress the oxygen that must react.

    Observe above-mentioned storing the main point, only harden the stability time limit of the resin in above one year.
    If quality makes a variation, please check above-mentioned main points and notify forever wide chemistry is measured and analysed for you.
  • Fundamental Principles of One Component Epoxy
    E01. The major ingredients of one component epoxy resin: It is almost the same as two component epoxy resin, including resin, hardener, diluent, catalyst, flexibilizer, filler, pigment, anti-sagging agent, defoamer, and so on.

    E02. The principle of one component epoxy resin: The epoxy resin must be mixed with hardener and catalyst to make the curing reaction occurs. The most common is placed resin in agent A and placed hardener & catalyst in agent B. If hardener is resin-insoluble, it can stay at ambient temperature, and the hardener will be dissolved in resin under high temperature and dispersed in the resin, that become one component epoxy resin. Furthermore, some catalysts and initiators have special temperature sensitivity, and they only react at a special temperature or higher. These can also be made into one component products.

    E03.Advantages of one component epoxy resin: 1. Don’t need to mix adhesives before using, simplifying processes. 2. One component system doesn’t need to measure A&B ratios. It could reduce the probability of errors. 3. The cost of one component dispensing equipment is lower than the two components. 4. One component system resin is relatively free of leftover materials and waste. 5. One component system epoxy resin doesn’t have limit of operating time.

    E04. Disadvantages of one component epoxy resin: 1. One component epoxy resin cannot cure at room temperature; instead, it should heat gradually. 2. Shelf life may be shorter. 3. It may need to be stored refrigerated (or even frozen).

    E05. The reasons why the viscosity of one component epoxy resin will increase viscosity when placing for a long time: The hardener in one component epoxy resin will slowly leach and react with the resin, which will cause the viscosity of the resin to gradually increase. This is the most common situation.

    E06. The reasons why the viscosity of one component epoxy resin will decrease viscosity when placing for a long time: Some of one component epoxy resins are added with anti-sagging agents to increase viscosity, and the particle surfaces of these additives have hydrogen bonds. This tiny force may cause the particles tend to agglomerate, and make the overall viscosity increase. However, the amine curing agent (powder) contained in one component epoxy resin can produce hydrogen bonds with the surface of the anti-sagging agent particles, it may replace the hydrogen bonds with the anti-sagging agent particles. It may cause anti-sagging properties to decline, and the viscosity decreases.

    E07.Factors affecting the stability of one component epoxy resin: 1. Moisture absorption of hardener will shorten the shelf life of the final products. It should pay attention to the humidity of the storage environment and keep the container tightly closed. 2. Generally, the lower storage temperature of final products, the more stable they are, but beware of the possibility of resin crystallization. 3. In formulations with lower viscosity often have precipitation or floating of certain ingredients, and result the poor final curing properties. 4. Some resins contain hydroxyl structures that cause gelation in low temperature systems. Some resins contain alkalis that cause instability in cationic polymerization. Some resins have excessively high levels of chlorine, which can affect the efficiency of alkaline catalysts. 5. The use of diluents will mostly reduce the curing reactivity, and will cause the viscosity to be unstable during storage.

    E08. Precautions for epoxy resin curing at different temperatures: Many applications will be cured at different temperature stages to avoid overly violent reactions while taking the account in the reaction rate. For resins and hardeners, two component epoxy resins are homogeneous systems, so there are not restrictions. What’s more, one component epoxy by use of epoxy powder hardeners which needs to consider the powder dissolved into the resin temperature. It cannot be arbitrarily arranged and combined; otherwise it may obtain incomplete curing results.

    E09. The two major components of composite materials: Usually includes substrate and reinforcing materials. In most cases, the former represents resin and the latter represents fiber. Composite materials are heterogeneous materials that combine the advantages of these two substances.

    E10. Functions of resins in composite materials: 1. Fix fibers in the right place. 2. Protect the fiber from abrasion damage. 3. Transfer mechanical force. 4. Control electrical, chemical, and other properties of composite materials. 5. Provides shear strength between compositing layer. 6. Determine the molding methods and processing parameters of composite materials.

    E11. Functions of fibers in composite materials: 1. To withstand the stress of composite materials. 2. Stop growing of tiny cracks. 3. Control mechanical properties of composite materials. 4. Improve creep resistance and fatigue resistance of composite materials. 5. Improve material service life and reliability.
  • Related Knowledge of One Component Epoxy
    F01. What's the key point of adhesion between epoxy resin and inorganic materials?
    In order to get a good adhesive effect, we must understand the principle of adhesion. 1. Balance theory. The simplest application is the consideration of surface tension. The surface tension of the resin must be reduced to effectively wet the surface of the substrate. 2. Molecular theory. Select appropriate functional group, so that there is a strong force between the adhesive molecule and the substrate molecule to obtain larger intermolecular binding energy. 3. The theory of adhesive speed. The resin must have suitable viscosity and thixotropy in order to expand and soak on the surface of the substrate and exert the maximum strength.

    F02. How to improve the adhesive performance by observing shape of the fracture surfaces of the test piece?
    The morphology of the broken test piece can be classified as follows: 1. The adhesive was delaminated, and one side of the test sheet had adhesive, and the other side had not. At this stage, we should try to make the adhesive on the both sides of the fracture surface test pieces. 2. The cracked surface of the test piece had adhesive on both sides. The surface was smooth flat, and the front end had micro cracks. At this stage, the adhesive itself was too brittle, lacked toughness, and the rupture energy was too low. 3. The cracked surface of the adhesive test piece had adhesive on both sides. The surface was extremely rough, and make an even standing lepidotes scales. This stage represented toughness of the adhesive was excellent, and the fracture energy was maximized to obtain the ideal adhesive strength.

    F03. Is there a relationship between the viscosity of adhesive and strength?
    Many customers express the adhesive strength in spoken language as viscosity. In fact, viscosity and adhesive strength are two different things. Under the same chemical structure, the adhesive with low viscosity has better penetrating ability to the surface of the material, and may obtain better adhesive strength. As for how high the viscosity is, the adhesive strength will be significantly reduced. Different conditions have different applications, and it should be verified by experiments. In general, the high viscosity occurs thixotropy phenomenon, the penetrating ability will be relatively poor. However, there are a few opposite examples. When the viscosity of the adhesive is too low, the thickness of the adhesive layer gets thicker with result in poor adhesive strength.

    F04. Is there any relationship between the adhesive strength of the adhesive and the test temperature?
    In the common lap strength test examples of the tensile stimulus mode, the higher temperature would get the lower adhesive strength. Furthermore, the temperature near or exceeding glass transition temperatures, and the adhesive strength will decrease significantly.

    F05. What’s the definition of Tg? Tg (Glass transition temperature) has a very strict academic definition: When a chain segment having 4 to 5 atoms on the macromolecule main chain which can move to the adjacent free volume at the same time, this temperature is called Tg. Besides, before and after Tg, the specific heat, expansion coefficient, modulus, dielectric constant, soft hardness, etc. all have obvious changes.

    F06. Does the resin with higher Tg have better heat resistance?
    Tg is not necessarily related to other things. For instance, Tg of silicon is quite low, but its heat resistance is good. Even if Tg of the resin combination composed a non-reactive diluent and an external plasticizer is higher than a resin combination composed of a reactive diluent and internal plasticization, its heat resistance is still much lower than the latter. Therefore, the relationship between Tg and heat resistance can only be discussed in the same manufacturer and in the same series combination. Once the important components are changed, which may affect the high-temperature cracking behavior, there may be no simple relationship between Tg and heat resistance.

    F07. Why cannot we be compared each other with different manufacturers of Tg in technical data sheet?
    There are many instruments for measuring Tg, which have different principles and definition. Even if it is the same type of instrument with different test conditions and different test piece conditions, even different instrument brands will provide differences. Taking DSC and DMA as examples, it is very common that Tg difference measured by the two exceeds 50°C. In addition, the technical data of many manufacturers only indicate the simple Tg value and do not explain the above details, so there is no benchmark for comparison at all. In order to understand how many degrees is Tg or which Tg brand is higher, the best method is to uniformly test the products of different manufacturers with a certain instrument at the same time. Such comparison has the highest level of confidence.

    F08 What is the thermal expansion coefficient of epoxy resin?
    In general, the thermal expansion coefficient of resins without inorganic fillers below Tg is about 80 ppm, and if it is above Tg, the thermal expansion coefficient is about 160 to 200 ppm. The thermal expansion coefficient of the resin containing inorganic filler is related to the volume ratio occupied by the inorganic filler: the higher the volume ratio, the lower the thermal expansion coefficient.

    F09. What is the shrinkage rate after the resin curing reaction?
    Generally, the epoxy resin without inorganic filler has a volume shrinkage rate about 3% and a linear shrinkage rate about 1%. Photocuring resin without inorganic fillers has a volume shrinkage rates about 8-10% and a linear shrinkage rate about 3%. The volume shrinkage rate of a resin containing inorganic filler is related to the volume ratio occupied by the inorganic filler: the higher volume ratios, it will get the lower shrinkage rate.

    F10. Why do some one component epoxy resins have bubbles after baking?
    (1) The exothermic reaction is too violent, and the phenomenon of cracking occurs, causing a large expansion of the volume, which looks like foaming. Lowering the temperature and prolonging the time can solve the above problems. (2) Some components in the resin formula have smaller molecular weight and bigger volatility, which are also the source of bubbles. (3) Air bubbles in the adhesive itself. Placing the adhesive on the glass to cure can distinguish the bubbles contained in the adhesive itself or the bubbles generated by the influence of the substrate. (4) Since the substrate is hygroscopic and damp, it releases water vapor and causes bubbles at high temperature. The most common examples are PC or Nylon. The solution is to heat the substrate at 100 ° C for a period, and this phenomenon can be eliminated.

    F11. Why do some epoxy resin formulations burst when they pass through a wave soldering?
    Some epoxy resin formulations use non-reactive diluents, plasticizers, etc. These additives will remain in the cured resin and it will volatilize when passing through a high temperature wave soldering, causing the cured material to burst. Besides, some epoxy resin compositions will decompose at high temperatures, so there will be cracking odor, and even foaming.

    F12. What is the highest temperature that epoxy resin can withstand for a long time?
    The temperature that the epoxy resin / amine hardener systems applied in the aerospace field can withstand is about 220 ~ 230 ℃. The temperature that the epoxy resin / anhydride hardener systems can withstand about 230 ~ 250 ℃. Due to the high processing temperature, the post-curing reaction needs to be performed at 220 ° C / 5 hrs, so it is rare in common epoxy resin applications.

    F13. How to evaluate the situation of thermal degradation?
    There are many assessment methods, and appropriate choices must be made from the practical application. For example, adhesives can be evaluated from changes in adhesive force before and after heating. The structural materials can be evaluated from changes in mechanical strength before and after heating. The coatings can be evaluated from color changes before and after heating. In addition to the actual product evaluation, TGA is used to measure thermal weight loss, but sometimes FTIR is used to observe changes in functional groups to reflect the status of thermal cracking.

    F14. What’s the source of outgassing?
    When organic materials are exposed to heat, vacuum, or under both gases often escape to make weight reduction. This phenomenon is called outgassing. Its causes may come from the following points: (1) By-products released during the condensation curing reaction of the resin. (2) Small molecules such as monomers, catalysts, diluents, additives, etc. remain after the resin is cured. (3) They are products when the resin cracks at high temperature.

    F15. What influences may cause outgassing?
    (1) Outgassing means the characteristics of the resin itself have changed. (2) Volatiles may contaminate the surface of the parts. (3) Volatiles may cause corrosion to electronic circuits. (4) Volatiles may cause cracks in plastic materials. (5) Volatiles may pollute the environment.

    F16. What are the principles of thermal adhesive and thermal grease?
    The thermal conductivity of air is only 0.03W/mK, so if there is a small gap between the heating element and the cooling element, the thermal efficiency will often be deteriorated. However, thermal adhesive and thermal grease are used to fill these gaps. Generally, the thermal conductivity of organic resin is about 0.3W/mK. Adding alumina in the resin is increase the thermal conductivity until 1W/mK. Adding aluminum nitride in the resin is increase the thermal conductivity until 2~3W/mK. Adding silver in the resin is increase the thermal conductivity until 7W/mK. The function of these materials is " conducting " the heat, and the transformed "the heat" should be depend on the heat-dissipation structure.
  • Fundamental Principles of Two component Epoxy
    C01. Epoxy resin is the second commonly used plastic in thermosetting resins, and its characteristics are as follows:
    1. It has excellent mechanical properties, strong cohesive force, and its strength is better than ordinary resin. 2. It has good adhesive strength, and it is suitable for metal, ceramic, glass, and so on. 3. It has low curing shrinkage rate that is only about 1 ~ 3%, which is one of the smallest types of thermosetting plastics. 4. It has good workability, and no volatile is generated during curing; furthermore, it is suitable for many different processing conditions. 5. It has good electrical performance, and its volume resistivity is above 1014W·cm. 6. It has high chemical stability, and it can withstand erosion from a variety of acids, alkalis and salts. 7. It has good heat resistance, which it generally can resist heat about 100 ℃, and special grades can hold up to 200 ℃.

    C02. The major components of two component epoxy resin:
    A part agent is resin. B part agent is hardener. In addition to these two components, it may add additives such as diluents, catalysts, tougheners, fillers, pigments, anti-sagging agents, defoamers, etc.

    C03. The major classification of resin in epoxy resin:
    It can be divided from raw materials: 1. Glycidyl ethers 2. Glycidyl esters 3. Glycidyl amines 4. Aliphatic epoxy compounds 5. Alicyclic epoxy compounds 6. Mixed epoxy resins. Point 1 and point 5 are the most commonly used.

    C04. Chlorine content of resin in epoxy resin: In the process of producing epoxy resin with epichlorohydrin as raw material, some side reactions occur. For example, the chlorine element will remain in the resin, forming two types of structure- hydrolyzable chlorine and non-hydrolyzable chlorine, which makes this type of epoxy resin have higher content of chlorine. What's more, content of chlorine in general grade resin is about 1,800 ppm. The cycloaliphatic epoxy resin compound production by peroxide does not bring chlorine into the epoxy resin, so the content of chlorine is extremely low.

    C05. The major classifications of hardener in epoxy resin: There are amines (including fatty amines, alicyclic amines, aromatic amines, polyamides, etc.), anhydrides, polymercaptans, and catalyst-type curing agents, etc.

    C06. Function of diluents in epoxy resin: The most common epoxy resin has a viscosity about 15,000 cps, and sometimes it is necessary to add a diluent to lower the viscosity. Diluents can be divided into reactive and non-reactive types. The former has a functional group that will react with the resin to become part of the structure, which has less impact on the overall characteristics. The latter means that the diluent does not react with the resin, so you must consider long-term effects when using, such as application temperature, environment, system compatibility, etc.

    C07. Function of catalysts in epoxy resin: It is used to increase the reaction rate between resin & hardener and shorten the curing time.

    C08. Function of tougheners in epoxy resin: Epoxy resin has a high crosslinking, so the cured materials are usually harder and brittle. Tougheners can improve the impact strength, destruction energy and tolerance of crack defects of the resin to avoid cracking during the environment test. The most famous example is liquid rubber, which can be evenly dispersed in the cured material to improve the toughness of the resin.

    C09. Function of fillers in epoxy resin: 1. Improve specific physical and mechanical properties. For instance, reduce curing shrinkage rate and thermal expansion coefficient, resist cracking, increase hardness, increase specific gravity, improve thermal conductivity, etc. 2. Improve workability. For example, improve viscosity, provide anti-sagging properties, provide grinding and cutting, and so on. 3. Reduce the cost. For example, change the proportion of resin, conduct incremental design of resin, etc. Furthermore, the properties of several functional fillers are as follows: alumina- thermal conductivity; aluminum hydroxide- flame retardancy and fire extinguishing; calcium carbonate- cost reduction; barium sulfate- increased specific gravity; talc- abrasive processing.

    C10. Function of anti-sagging agents in epoxy resin: Anti-sagging agents form a continuous three-dimensional network structure in the resin by hydrogen bonding with each other, trapping the resin in the middle of the structure to avoid flowing randomly. The network structure will be damaged when external force is present, causing the overall viscosity to drop, which is convenient for construction. When the external force disappears, the network structure will restore. Therefore, functions of anti-sagging agents in epoxy resin are: 1. Prevent uncured resin from flowing freely. 2. Prevent filler from precipitating in resin. 3. Provide thixotropic flow behavior for resin.

    C11. Function of defoamers in epoxy resin:
    Epoxy resins may generate bubbles during the process of manufacturing, mixing, and processing. An anti-foaming agent can more easily to break bubbles, and obtain a good appearance of products.
  • Related Knowledge of Two component Epoxy
    D01. What causes epoxy resin to crystallize? The most widely used epoxy resins which are crystalline solids at room temperature, and its melting point is about 45℃. These resins usually look like clear liquids because they are in a supercooled state. The crystallization speed would be very slow, and sometimes they need to stand for several months before crystallization occurs. When the storage temperature is higher, the driving force of thermodynamic crystallization would be lower and it is less likely to crystallize. Furthermore, the resin is placed at very low temperature, the crystallization speed becomes slow due to the viscosity of the resin increase, so it is not easy to crystallize. When the resin is placed at 10 ℃, the crystallization speed is the fastest. The resins with low chlorine content, narrow distribution of molecular weight and the higher the purity have the easier crystallize.

    D02. How to deal with when epoxy resin crystallizes? Theoretically, the crystal epoxy resin may be melted as long as heated at 60 ℃. The A agent of two component resin can be treated as such without filler. Furthermore, if it can stir after heating, it would ensure the uniformity of the products. If agent A is added epoxy filler in the two-component epoxy resin, it is necessary to stir it again after heating to avoid the precipitation of certain ingredients and causing uneven.

    D03. What is the reason of the amine curing agent agglomerating? Some fatty amine curing agents have high hydrophilicity, so they will quickly absorb moisture and carbon dioxide in the air and react to form ammonium carbonate. However, ammonium carbonate cannot dissolve in the original fatty amine, agglomeration will occur. If these ammonium carbonates can dissolve in the original fatty amines, agglomeration will not occur, but they will cause yellowing of the fatty amines, poor curing reaction with resins, reducing mechanical strength, and foaming during heating. Thus, packaging containers for amine curing agents must be tightly closed.

    D04. What is the reason of the anhydride curing agents agglomerating? Anhydride is formed by dehydration reaction of dibasic acid, so it is easy to reabsorb moisture in the air and generate dibasic acid. Dibasic acid produced after the water absorption of the anhydride cannot dissolve in the original anhydride, so the initial period of the water absorption of the anhydride looks a little turbid. There will be some precipitate, and it looks like agglomeration in serious cases. Besides, the phenomenon of agglomeration is particularly obvious near the bottle mouth, so the packaging container of the anhydride curing agent must be tightly closed.

    D05. Why epoxy resins become oily and foggy after curing? There are three possible reasons: (1) Improper use of defoaming agent and leveling agent. (2) The compatibility of epoxy resin and hardener are not good, so some of the hardener floats on the surface. (3) The hardeners are absorbed moisture and carbon dioxide. In addition, this phenomenon is particularly noticeable under conditions of high humidity, low temperature, and slow reaction speed.

    D06. What is the definition of gel time? Gel time means the resin reacts until it flows hardly, and then forms a colloid. The reaction rate of the resin reaches gel which is about 30% to 40%, and it depends on the composition. When recording the gel time, it must record both the ambient temperature and the resin weight. However, the gel time is not a very precise value. Some resins have slow reaction time, so the using time can be several hours. Therefore, it is not suitable to indicate an exact gel time value, and it instead recommended pot life.

    D07. What’s the definition of pot life? Pot life is a time range which customers can use the resin. Because customers use resin in different ways, the definition of pot life will vary from case to case. Some pot life refers to the time that the viscosity of resin is less than 10,000Cps, and some pot life refers to the time that the viscosity of resin is less than twice the initial value. Some confusion about the pot life and gel time. Like the gel time and the pot life are not a very precise value. When recording the pot life, it must record both the ambient temperature and resin weight; in general, the higher the ambient temperature and the heavier the resin weight may exhibit shorter pot life.

    D08. What is the exothermic phenomenon of resin curing reaction? When resin is conducting curing process, it mostly releases heat. This heat will increase own temperature of resin and make the reaction faster and faster. When the temperature of resin rises higher, it may cause components failure to generate huge stresses, and the component also would be damage during cooling down the temperature. The simplest way to evaluate the exothermic reaction of resin is to be used in a thermometer to record the relationship between temperature and time at a specific weight of resin and a specific ambient temperature (usually 25 °C). The exothermic reaction curve of the resin is that the temperature data of the above data is listed as the vertical coordinate, and the time is listed as the horizontal coordinate.

    D09. What’s the relationship between the curing speed of the resin and the reaction temperature of the resin? According to the Arrhenius equation, the reaction rate (R) and the activation energy (Ea) of the reaction have proportional relationship as follows: From R  Exp(-Ea/RT) this relation, it can be deduced when the temperature rises by 10 °C, and the reaction rate is two times faster than the original rate. In contrast, the temperature drops by 10 °C, the reaction rate is about 1/2 times slower than of the original rate.

    D10. Epoxy resin / Hardener = 100/50. Can you increase the amount of hardener to improve the reaction speed when the reaction rate is slow?
    Answer: No. The ratio between epoxy resin and hardener are calculated, and only minor error value is allowed. Any change of the ratio will cause the properties of cured material deterioration. By the way, increasing the amount of hardener does not make the curing speed faster of epoxy resin.

    D11. Can epoxy resin react completely? There is not "complete reaction" in thermosetting resins, only the problem of how much the reaction rate is. Epoxy resin is also a typical example of this. The reaction of two functional groups (resin and hardener) needs to break through the activation energy of the reaction, especially after the resin is cured, the functional groups must rely on diffusion motion to connect. With the increase of the reaction rate, the concentration of functional groups will gradually decrease, and the energy requirement for diffusion movement will also increase at the same time. In the end, the activation energy of further reactions may be higher than the activation energy of some structural, making the resin hardly achieve a complete reaction.

    D12. Is the high reaction rate, the better? The properties of many polymers are related to their reaction rates. For instances, the higher reaction rate may create a better glass transition, hardness, heat resistance, mechanical strength, etc. Some macromolecule characteristics are not necessarily related to the reaction rate, such as adhesive strength and slow rupture energy. In practice, the appropriate reaction rate is enough. The pursuit of a high reaction rate sometimes can lead to lengthy manufacturing processes, sometimes can lead to increased costs, and sometimes can't be achieved at all. Taking epoxy floor paint as an example, the reaction rate after 7 days at room temperature is 70% and 75%, which is enough to meet the requirements of dust-free floor hardness and scratch resistance. It is not necessary and cannot be further improved the reaction rate of floor paint. Lots of examples are enough to explain that it is not necessary to pursue a high reaction rate, and the real issue is the appropriate reaction rates.

    D13. Why is the curing condition of all room temperature epoxy resins written placing at room temperature for 7 days? The most common room temperature is 25 ℃, but in fact the room temperature itself is not a stable temperature; instead, it is a possible range between 10 ℃ and 30 ℃. The curing time of the epoxy resin is a wide range when writing, in order to respond changes of room temperature. Some epoxy resins have poor curing phenomenon below 10 ℃, it is not easy to produce good strength even after being placed for a long time; therefore, it must pay attention at curing environment below 10 ℃.

    D14. What is the biggest difference between soft epoxy resin and soft PU? PU molecules have strong hydrogen bonds each other to form a special physical link, so it exhibits excellent flexibility. The structure of epoxy resins is different even if it uses toughening agents and softeners to reduce the crosslinking density, the performance of soft epoxy in repeated bending is not as good as PU. Besides, the reaction speed of soft epoxy resin is slow, so the hardness tends to increase gradually.

    D15. Can the cured resin be removed with a solvent? When the thermosetting resin is cured, it can no longer dissolve in a solvent. Otherwise, soaking them in an appropriate ratio of solvent, these plastics will absorb the solvent and then swell, soften, lose strength, and even break into tiny rubber particles. Furthermore, commercially available paint removers use this principle to select high boiling point and high polarity solvent combinations to achieve the purpose of removing cured resin.

    D16. How to make plastic flame retardancy? In some plastic structures, the proportions of aromatics are very large, the LOI (Limited oxygen index) value are very high and the char yield after burning are high, so they have flame retardancy themselves, such as phenol-formaldehyde resin and furan resin. Other plastics (such as epoxy resin, photocuring resin) must add flame retardant to achieve flame retardancy. In addition, flame retardants can be divided into halogen-based, phosphorus-based, nitrogen-based and inorganic systems, etc. Most of these flame retardants are addition type, and only a few are reactive type, but both will affect the characteristics of the resin.

    D17. What should need attention in the application of two component dispensers?
    (1) In the application of two component dispensers, you should pay attention to whether the four parameters of viscosity, thixotropy, specific gravity, and compatibility, which the difference of the resin and the hardener are too large, to avoid the problem of uneven mixing during use. (2) Before using a two-component dispenser, you must press out some adhesive first to avoid inconsistent amounts of adhesive. (3) To confirm whether length and type of the selected mixing hose can meet the needs of uniform stirring.
  • Fundamental Principles of Photocuring Resin
    A01. According to the polymerizing reaction mechanism, the photocuring resins are divided into the following two categories: 1. Acrylic resin polymerized by free radicals. 2. Epoxy resin polymerized by cations.

    A02. The main components of photocuring acrylic resin: oligomers, monomers, initiators, and other additives.

    A03. The oligomers commonly used in acrylic resins: Epoxy Acrylates, Urethane Acrylates, Polyether Acrylates, etc. The structures of these oligomers are the introduction of acrylic functional groups at the ends of the original resin structure, enabling them to carry out free radical polymerization.

    A04. The monomers commonly used in acrylic resins: Monofunctional groups, difunctional groups and polyfunctional groups, etc. are mostly dehydrated esters produced by the reaction of acrylic acid with alcohols and dehydration. Different structures have different characteristics.

    A05. Reaction principle of photo-initiator for UV curing acrylic resin: Photo-initiators absorb the energy of specific light and generate free radicals. Both oligomers and monomers have acrylic functional groups, they can react with free radicals to achieve the purpose of photocuring.

    A06. Reaction principle of photocuring epoxy resin: The composition of photocuring epoxy resin includes initiators, oligomers, monomers, modifiers, and so on. In addition, when initiators are irradiated with light, cations will be generated to initiate the polymerization reaction.

    A07. The advantages of photocurable epoxy resin: Compared to acrylic resin, epoxy resin has a lower shrinkage rates, higher heat resistance, chemical resistance, and moisture resistance. Besides, epoxy resin is hardly affected by oxygen, and it has lower volatility, which is less likely to irritate the skin.

    A08. The disadvantages of photocurable epoxy resin: Compared to acrylic resin, epoxy resin has slower reaction speed, shallower reaction depth, lower absorption wavelength for initiators, and narrower absorption ranges. What’s more, there are fewer types of monomers and oligomers in the epoxy resin systems, which affects the variability of the formulation.

    A09. Effect of the absorption wavelength of the initiator on the photocuring reaction: The absorption of light by the initiator is a continuous spectrum. Initiator with low absorption wavelength is suitable for increasing the surface curing rate of photocurable epoxy resin. An initiator with an absorption wavelength near blue light is suitable for transparent materials, but it cannot be penetrated by ultraviolet light. The absorption wavelength of some initiators can be as high as 550nm or more, which has very strong reactivity and needs to be used in a yellow or dark place.

    A10. Effect of the absorptive sensitivity of the initiator on the photocuring reaction: High-sensitivity initiators has higher initial efficiency, which can achieve the same effect in the case of weak light intensity or low light energy. It is suitable for dark photocuring systems.

    A11. Effect of the emission wavelength of light source on the photocuring reaction: The light source provides light to be absorbed by the initiator and performs a photocuring reaction. The light source widely used in photocuring systems is a high-pressure mercury lamp, whose maximum emission wavelength is 365nm. Furthermore, a halogen lamp can be made by doping a part of metal halides in a high-pressure mercury lamp, and its maximum emission wavelength appears between 400 ~ 450 nm near blue light. Different applications can be achieved through different initiators and different light sources.

    A12. Radiant energy required for photocuring reaction: A photocuring acrylic resin based requires about 800 ~ 2000mJ / cm2 for reaction at 365nm. The photocurable epoxy resin requires about 3000 ~ 6000mJ / cm2. The amount of radiant energy depends mainly on the demands for rate of reaction.

    A13. Representative wavelengths of ultraviolet and visible light: UV light (long wave) is 365nm; UV light (short wave) is 254nm; visible light (blue light) is 436nm.
  • Related knowledge of photocuring resin
    B01. What is the irradiation of a general flat UV lamp?
    Take the following picture about 400W ultraviolet light source as an example. It mainly emits ultraviolet light with UV-A wavelength of 365nm and visible light around 400-440nm. The irradiation measured at about 10 cm below the bulb were 120 mW / cm2 (365 nm) and 80 mW / cm2 (436 nm). What’s more, irradiation is inversely proportional to the square of the distance, and will decrease rapidly as the distance increases.

    B02. What is the irradiation of general point source?
    Irradiation of common point source, ultraviolet light source has at least 800-1000 mW / cm2 (365nm) at the front part of the light pipe, and the higher irradiation can reach more than 2000 mW / cm2 (365nm). However, some point source visible light sources are used to project indirect light whose irradiation of ultraviolet light is only about 20 mW / cm2 (365 nm) or even lower. These lights need to be clearly distinguished.

    B03. What effect does UV adhesive have when the irradiation increases?
    Too strong irradiation has a negative impact on the properties of the acrylic UV adhesive. For instance, increasing the irradiation by n times can increase the initial reaction rate by n times, generate n times of free radicals, and increase the growth rate by n times. However, at the same time, the speed of stopping the reaction will increase n2 times. In other words, too strong irradiation will reduce the molecular weight of the adhesive and the molecular chain will be changed, so the optimal strength will not be obtained.

    B04. What effect does UV adhesive have when the radiant energy becomes large?
    In general, the acrylic UV adhesive would rather irradiate too much energy than insufficient radiant energy. Regardless of theory or practice, even if the radiant energy of this type of UV adhesive exceeds 10 times the original recommended value, there are no obvious negative effects. Furthermore, it is speculated that the radiant energy should be hundreds of times more than the original recommended value, and then there will be obvious concerns about photoaging reactions.

    B05. What are the concerns when acrylic UV adhesive has insufficient radiant energy?
    When the acrylic UV adhesive is irradiated insufficiently, a lot of acrylic monomers will remain in the UV adhesive. These residual monomers will be a role of plasticizers in UV adhesive in initial stage, so the results are low hardness, insufficient strength, high water absorption, and poor environmental performance. As the usage time increases, these monomers will gradually volatilize, causing the adhesive to gradually cure and the physical properties to be unstable. Some practical cases point out that these monomers may diffuse into the plastic substrates, causing cracks in these plastics (such as PC, Acrylates, etc.); therefore, it is necessary to avoid the situation of insufficient radiant energy.

    B06. What causes UV adhesives having poor surface dryness?
    Photocuring acrylic resin is based on the reaction of free radicals with monomers to generate new free radicals; however, free radicals also react with oxygen in the air to produce peroxide free radicals. The reaction rate of free radicals with oxygen is hundreds of times faster than the reaction rate of free radicals with monomers, while the reaction rate of peroxide radicals generated by the former with monomers is very slow, which affects the reaction speed. Besides, this effect is most obvious at the location where the resin is in contact with the air (usually surface). In slight situation, the reaction rate of the resin surface is slightly lower and the scratch resistance is poor; more seriously, the surface will feel sticky when touched; when the film is thin, it may not completely cure.

    B07. What is the reaction principle of UV + anaerobic adhesive?
    Acrylic resins can undergo chain polymerization in the presence of free radicals. The photoinitiator can absorb specific light to generate free radicals, or free radicals can be obtained by using temperature to decompose the thermal initiator (peroxide). The reaction of the UV + anaerobic adhesive is to add a thermal initiator to the UV adhesive. When both the occurrence of the metal catalyst and the isolating of oxygen (air) occur, the free radicals obtained from decomposing thermal initiator will cause UV adhesive undergoes curing reaction without irradiating light. Furthermore, the appearance of metal catalysts can reduce the decomposition temperature of peroxides, and the source may be the surface of metal substrate or a pre-coated primer. The reason why oxygen (air) needs to be isolated because oxygen will react with the inhibitor to consume the free radicals generated by peroxide and hinder the curing reaction. Therefore, oxygen needs to be isolated to perform the anaerobic curing reaction.

    B08. What should we pay attention when packaging UV adhesives?
    1. Store it in a cool dry place away from sunlight. 2. Store in a cool and well-ventilated place. 3. Do not change the resin packaging at random. 4. Select the appropriate container for packaging (for example: PE, PP plastic buckets, stainless steel buckets, black steel pail, or opaque glassware). 5. Avoid contacting with metals such as copper and iron, which they will cause polymerization. 6. Don't evacuate the resin. 7. Do not fill resin packaging with nitrogen or oxygen-free gas. 8. Do not fill the container with resin fully. There must be space in the container to provide the oxygen needed to suppress the reaction.

    B09. Why do some UV adhesives need post cure(heated), but some do not?
    The free radical polymerization of acrylate resins which free radical life is very short, only about tens of ns (negative 9th power of 10 seconds). In other words, acrylic photocuring resin will generate free radicals to polymerize when exposed to light; when the light is stopped, the free radicals disappear immediately and cannot be further reacted. However, epoxy-based photocuring resins generate cations to polymerize when irradiated with light. The cations do not disappear immediately when the light is stopped, and the life span after stopping the light can be up to two or three days. Therefore, if it is post cured by heating at this stage, every property of the cured material can be further improved. This characteristic is called live polymerization. What’s more, post cure can not only improve the reaction rate, but also relieve the internal stress. Thus, many hard adhesives must be annealed by post cure to obtain the best performance.

    B10. What are the possible inhibited reactions of cationic polymerized photocuring epoxy resins may occur?
    Cationic polymerization relies on a strong protic acid to perform the reaction, so any alkaline substance may inhibit the above-mentioned reaction, resulting in poor curing or even being unable to react. Furthermore, the source of alkaline substances not only comes from the raw materials of adhesive itself, but also the composition of surface of substrate or extrinsic contaminant. These conditions can be overcome by cleaning the surface of substrate, and perhaps can be improved by using solvent to wipe. Be very careful when the surface is contaminated, and always be vigilant. Once upon a time, acrylic systems UV adhesive was being used nearby, and its steam scattered in the air, which caused the cationic polymerized epoxy resin fail to react.

    B11. Can photocuring resins completely react?
    Like common thermosetting resins, photocuring resins do not fully react. In terms of the number of acrylic functional groups, the reaction rate of the photocuring resin is about 80% to 90%, and some functional groups will be left over. Moreover, the reaction rate of a polyfunctional monomer is lower than that of a monofunctional monomer, and the residual amounts of the functional groups are large. From the perspective of the photo-initiator, the photocuring reaction will only consume 20% to 30% of the photo-initiator, and the remaining photo-initiator will remain in the cured material.

    B12. How to measure water absorption rate?
    The simplest way is to soak the test piece in water at a specific temperature, and take it out after a specific time, and then measure the weight change to get the water absorption rate.

    B13. Does the cured resin of water absorption rate sure more than 0?
    Most cured resins will gain weight after soaking in water. To put it another way, lots of water absorption rate of curing resins is more than 0. Some compositions of resins will dissolve in water during the test, causing the weight loss of whole resin, that is, its water absorption rate will be less than 0.

    B14. How to evaluate the applicability of adhesives for plastic substrates?
    For the bonding adhesive, achieved good adhesion to plastic, there are some requirements as follows: 1. Be able to swell the substrate. 2. Can form interpenetrating polymer network ((IPN, Interpenetrating polymer network) with substrate. Regards to the first point, there is a very simple evaluation method, which apply the liquid adhesive on the plastic substrate and wipe it after a few minutes to observe whether the surface of plastic become white, fog, etc. Regards to the second point, since you must refer to the relevant literature and accumulated experimental experience to get results, you cannot make quick guesses.

    B15. Which plastic materials are suitable for UV adhesive?
    The acrylic UV adhesive is most suitable for the following plastic materials: PC, ABS, PVC, PS, Acrylate, MS, SAN, etc. The acrylic UV adhesive can try to bond at the following plastic materials: Nylon, PET, PBT, etc. Without surface treatment, the acrylic UV adhesive cannot bond the following plastic materials: PE, PP, Silicon, etc.

    B16. When dyeing the transparent plastics, which color may be cured with UV adhesive? Which color is difficult to cure with UV adhesive?
    In principle, red is the most difficult to cure, orange has a chance, and blue should be the easiest. After the plastic is dyed, it is best to use a high-sensitivity photo initiator to improve the reaction ability. As for whether the UV adhesive can be properly cured which is also affected by the depth of the color, the thickness of the plastic, etc. There can be no general rule to follow.

    B17. How to evaluate whether transparent plastic materials can penetrate UV light?
    The simplest way is to take two pieces of plastic sheets, dispense UV adhesive in the middle of two plastic sheets, and then put it under the UV lamp to expose. Whether the UV cured adhesive or can’t observe whether UV light can penetrate the material. What’s more, the digitized method is to place the plastic sheet on the lux meter and then expose it under a UV lamp. The reading of the lux meter can be used to obtain the transmittance of the material to a specific UV wavelength.

    B18. Why does the viscosity of resin products vary considerably?
    Many organic polymers are not pure substances. There are homologs, by-products, etc. simultaneously exist. Manufacturers will control the content and proportion of these substances within a range, but not every batch will be exactly the same, so the viscosity of resin will change by a certain amount.

    B19. Why can’t the viscosity in the technical data of different manufacturers be compared with each other?
    Viscosity will vary depending on the speed of the viscometer, the geometry of the rotor, the basis for data reading, the principle of instrument testing, whether calibrate or not, and the accuracy of temperature control. In the measurement of low-viscosity and Newtonian fluids, the above-mentioned differences are small; in the measurement of high viscosity and non-Newtonian fluids, the differences in data between different manufacturers may be very large. Therefore, in order to understand how much the viscosity is, the best way is to test the products of different manufacturers by a certain instrument at the same time, so that the comparison has the highest level of confidence.

    B20. What’s the relationship between viscosity and temperature?
    According to the Arrhenius equation, the viscosity (η) and temperature (T) have the following proportional relationship: η Exp(-Ea/RT). From this relation, it can be deduced that when the temperature rises by 10 ° C, the viscosity is about 1/2 of the original. In contrast, when the temperature drops by 10 ° C, the viscosity is about twice of the original. The above relationship is roughly applicable to Newtonian fluids which is homogeneous (without inorganic fillers), but the differences are larger in heterogeneous and non-Newtonian fluids system.

    B21. Can all surface treatment significantly adhesion improvement?
    Not sure. It depends on what caused the adhesion failure. If the cause of the adhesion failure is delamination between the adhesive and the substrate, we can conduct surface treatment of the substrate to improve the adhesive strength; if the cause of the adhesion failure is insufficient mechanical strength of the adhesive itself, surface treatment of the substrate cannot improve the adhesive strength.

    B22. How to conduct surface treatment?
    (1) Grinding: Use mechanical stress such as: wiping, sandblasting, etc. to remove oxides and dust on the surface of the object, and achieves the purpose of roughening the surface of the object, increasing the bonding area, and increasing the anchoring effect. (2) Solvent cleaning: You can soak the object in the solvent, use ultrasonic vibration, wipe it directly, or use the solvent vapor to remove the oil stains, organic impurities, and pollutants on the surface to achieve the purpose of cleaning the surface. (3) Degreasing with hot lye: Sometimes use soap or slightly stronger lye to remove the oil on the surface, but these cleaners must be washed afterwards to avoid remaining on the surface of the object. (4) Chemical etching: Use chemical agents or flame treatment to remove oxides, improve the reactivity of the surface of materials, create new surface functional groups, increase the anchoring effect, and so on. (5) Physical and chemical etching: Use corona treatment, plasma treatment or UV irradiation to change the surface structure, create new surface functional groups, increase the anchoring effect, etc. (6) Create a new surface: The surface of the metal is plated with a different metal than the raw material to improve the adhesive effect.

    B23. What are the functions of surface treatment?
    (1) Clean the surface of the object. (2) Improve the anchoring effect of adhesive or primer. (3) Increase the wettability of the surface of the object. (4) Establish chemical bonds between the surface of the substance and the adhesive or primer

    B24. What are common types and functions of primer?
    The types and functions of primer are quite diverse, which are listed below: 1. Organic Silane. It is used to establish chemical bonds between inorganic surfaces and organic materials. 2. Organometal. It is commonly used in anaerobic adhesive system to increase the curing rate of anaerobic adhesives. 3. Alkaline catalyst. It is commonly used in superglue system to increase the curing rate. 4. Long-chain fatty amines. It is often used in superglue systems to increase the curing rate of superglue and improve the adhesion to PE, PP, and Silicon. 5. Chlorinated rubber. It is applied on the surface of PE and PP to improve the adhesive strength of the adhesive. 6. Solvent-based adhesive. It is applied on the surface of the substrate and uses the solvent-based penetrating ability to create a higher anchoring effect and improve the adhesive effect. 7. Other chemicals. They sometimes are used as an interface compatibilizer, sometimes using electrostatic absorbability, sometimes improving anti-corrosion ability of the surface, etc. to improve the adhesion effect.

    B25. Why are rubber materials not easy to adhere?
    First, there are many types of rubber, so most of the customers are confused, including many non-rubber elastomers, which are also mistaken for rubber. Second, the softness, flexibility, and compressibility of rubber are quite good. Therefore, it is difficult for the adhesive to endure such large and multiple directions of deformation. Third, the molecular structure of rubber has almost no polarity and low surface tension, so it is difficult for the adhesive to develop a strong force with rubber. Sometimes, additives such as processing oil are used in the production of rubber. The appearance of these additives on the rubber surface causes the rubber material to be not easy to adhere.

    B26. Why do Nylon, PET, etc are not easy to adhere?
    Nylon and PET are both crystalline polymers, and they are quite resistant to chemical corrosion, so they are not easily swelled by the composition of epoxy resin or photocuring resin. Chemical substances such as phenols or some high-boiling solvents, which have good compatibility with Nylon and PET are not easy to introduce into the structure of adhesives, so Nylon and PET have been quite troublesome in adhering. Nylon and PET can use thermosetting epoxy resin to obtain a better adhesive effect. Moreover, roughening the surface of the substrate can also improve the adhesive strength. Some commercially available PET surfaces will conduct corona treatment, and some PET surface layers are amorphous PET, which both can effectively improve the adhesive problems. They are materials recommended to customers. Some PET surfaces have been hard-coated. The results of this type of modification will increase the difficulty of adhesion, and other resin formulations with better affinity for inorganic systems must be tested.

    B27. Why do PE, PP, etc are not easy to adhere?
    PE and PP are non-polar and high crystallinity materials. Due to their low polarity, it is difficult for adhesives to wet them well and establish good bonds; plus, because of their high crystallinity, not suitable composition can swell the surface of plastic, so there is no suitable adhesive for plastics such as PE and PP. However, instant adhesive combined with primer which is chlorinated PP can partially improve the adhesion to PE and PP by using flame treatment to surface and corona treatment, etc., but it is usually not a good solution due to equipment or process limitations.
  • Instructions for using Everwide one component dispensing gun
    one component dispensing gun and hose
    Push up the push rod behind the dispensing gun and install the stripper plate. (Insection face down)
    Insert extendable stripper plate from gun head (Insection facing down)
    Push the stripper plate backwards or pull it to the bottom
    Pull the push rod to the bottom and fix it (front)
    Pull the push rod to the bottom and fix it (front)
    Open the safety clasp
    Fasten the tail of one component hose into the slot to fix it
    Fasten the tail of one component hose into the slot to fix it
    Buckle up the safety clasp
    Tightly fasten the safety clasp and press it to the end
    Successful combination of one component hose and dispensing gun
    Press the wrench to let the push plate push the piston behind the tube to release the glue.
    Open the safety clasp after using it
    Push up the rear push rod and pull it backwards to the bottom
    Remove the hose to complete the job
  • Precautions for using UV Cureable Resin
    The following are the protective items you need to prepare before using our company's UV cureable resin, and explain how to wear protective gears step by step.
    Step 1
    wear goggles

    Step 2
    There will be two layers when wearing gloves
    Inner layer (general PE gloves)
    Outer layer (latex gloves)
    wear face mask

    Pay attention to the environment when using the glue.
    The environment should be well-ventilated when you using.
    If the body or hands are stained with the glue, you should immediately wipe with the following two solvents: IPA and Acetone.
    After wiping hands with solvent, you may wash hands with soap and dry hands with a dry cloth before starting work.
    UV Cureable will contain N-Vinyl-2-Pyrrolidone (CAS No: 88-12-0). This material is non-toxic, but it will cause skin redness and itch.
  • Everwide Chemical Company FS series STPU Moisture-curring type resin packaging assembly Pneumatic packaging
    Introduction of Air packaging
    Dedicated adapter assembly for large hose to small hose
    Adapter
    FS series product 300ML hose
    Combine small-sized hose with inner plug
    Use finger or tool to press inner plug to the bottom
    Please press inner plug to the bottom
    Air equipments and packaging sleeve tools
    Put a 300ml hose into an aluminum pneumatic sleeve
    Lock the back cover with a gasket inside to prevent air leak from affecting the adhesive pressure coefficient
    Connect the pneumatic dispenser to the air inlet pipe and turn on the power
    Aluminum sleeve installed on the air-outlet end of a pneumatic dispenser
    Please buckle the fixing groove according to the structure
    Adjust air-output pressure
    Setting the packaged time
    Dispensing can be done after installation
    Perform packaging operation and install adapter kits
    Then install into the pneumatic sleeve and expose the adapter
    Install small size empty hose. Please tighten it.
    Prepare to package
    Control the air pressure according to the viscosity of the rubber material to determine the packaging speed
    Continue to dispense until required amount
    "Remove the hose and cover the lid
    Replace with the new empty hose, and then package"
    Continue to package after adapt
    Remove the hose after dispensing. Complete packaging.
    Complete packaging and clean it up.
    Remove the adapter after dispensing and clean the remaining glue in the hose
    Then put it into solvent to soak and wash. (MEK or Acetone)
    Please clean the front side of the big hose, screw the head plug tightly, and keep it dry.
  • Impact of environmental factors in the new process on resin
    Analytical Model
    Dear: I think the scope of the problem should be narrowed down a little bit. The state of opening cup can not be explained entirely. Let us assume it is closed.
    Space affected by environmental factors
    Assume that the volume of the sealed cup is 1000ml, the upper space is 300ml, and the underlayer resin is 700ml.
    The upper space 300ml is the source of moisture, which will allow the resin to absorb moisture and affect the characteristics. The air in the upper space of the cup comes from the production line.
    Suppose the temperature (relative humidity and air pressure) of production line are 25 ℃, RH 85%, 1atm. Then there will be 0.0059g of water in 300ml.
    Water content under different temperature and humidity conditions
    Temperature℃
    Relative humidity %
    Air pressure (atm)
    Absolute humidity (g/m3)
    Moisture content in 300ml space
    Factor affecting moisture content
    "Calculated based on the worst production line environment. 40℃. RH 100%. 1atm. Then there will be 0.0153 g of water in 300ml.
    0.0153 g / 18 (g/mol) = 0.00085 mol of water.
    If all water reacts with the hardener, 0.0017 mol of -COOH will be formed.
    "
    The calculation of the most extreme also prove that the impact is small.
    "In 700ml of resin, we designed the theoretical content of -COOH to be 0.298 mol. In other words, all the water in the environment reacts with the hardener form 0.0017 mol of -COOH, which only accounts for 0.57% of the original -COOH content.
    In fact, the actual value must be much lower than the 0.57% data, which is 100% reaction between water and hardener. However, the actual situation is that the reaction between water and hardener is not fast. According to the literature, the reaction rate between the two within 10 hours is only about 6%. Anyway, the value of 0.57% has no effect on this system. It is almost impossible to measure, and the error of the mixing scale is much larger than it. The above comments are for your reference."
    What if the water does not react when disolving to the resin?
    "According to the previous experiment hypothesis, 0.0153 g of water was suddenly dissolved in 700 ml of resin, and it was not consumed by reaction with the hardener.
    How much water will be added to the system?
    0.0153 / (700*1.57) = 1.39*10 -5 = 13.9 ppm
    The moisture content of our raw resin is 200 ~ 300 ppm
    Water content of quartz powder is 400 ~ 800 ppm
    We used to add 1000 ppm of water in the finished product, and the properties of the hardened material were not affected. Because the 13.9ppm humidity in the air , the value is really low. Not to mention that they will not disolve through in a short time."