Low-modulus and high-adhesion UV adhesive as well as preparation method and application thereof

Abstract

The invention provides a low-modulus and high-adhesion UV adhesive and a preparation method and application thereof.The low-modulus and high-adhesion UV adhesive is prepared from polycarbonate type polyurethane acrylate resin, N, N-dimethylacrylamide, hydroxyethyl acrylate, tripropylene glycol diacrylate, ethyoxyl ethyoxyl ethyl acrylate, vinyl chloride and vinyl acetate copolymer resin, bis (2, 4, 6-trimethyl-1, 3-pentanediol) (2, 4, 6-trimethyl-1, 3, 6-trimethyl-1, 3, 6-trimethyl-1, 3, 6-trimethyl-1, 3, 6-trimethyl-1, 3, 6-trimethyl-1, 3, 6-trimethyl-1, 3-pentanediol The coating is prepared from the following raw materials: 4-(2, 6-trimethylbenzoyl) phenyl phosphine oxide, 2-hydroxy-2-methyl-1-phenyl-1-[4-(2-hydroxyethoxy) phenyl] acetone, TPO (Thermoplastic Polyolefin), vinyl triethoxy silane, vinyl trimethoxy silane, a diluent and a de-foaming agent. The adhesive provided by the invention can be used for welding spot protection, prism fixation, glass and plastic bonding, structural member bonding and the like. Due to the low modulus, stress can be released during welding spot protection and structural part bonding, and the phenomena of cracking, layering and the like caused by stress residues are avoided, and functional failure of a product is avoided; and due to high adhesion, the product can be better protected, and the product has the characteristics of high vibration resistance, impact resistance, high and low temperature resistance and the like.

Description

Technical Field

[0001] The present application belongs to the technical field of adhesives, and in particular relates to a low modulus, high-adhesion UV adhesive and a preparation method and application thereof. Background Art

[0002] UV adhesive is an adhesive that cures quickly under ultraviolet light. In recent years, with the advancement of light-curing technology, the application scope of UV adhesives has continued to expand, especially in areas that require high efficiency and environmental protection. At the same time, with the increasing requirements for environmental protection, UV adhesives are favored for their low volatile organic compounds (VOCs) emissions and are widely used in electronics, optics, medical and other fields.

[0003] Although traditional UV adhesives have a fast curing speed, their insufficient adhesion and high modulus on certain special materials limit their application. In addition, existing UV adhesives do not cure well under low-intensity light conditions, and the initial strength after UV curing is low, which cannot meet the requirements of handling and process connection in actual applications of adhesives, affecting their performance in actual applications.

[0004] Existing UV adhesives have at least one of the following disadvantages:

[0005] 1. Insufficient adhesion: Some UV adhesives have weak adhesion, and the products are prone to falling off during use, which limits their application range.

[0006] 2. High modulus: After the structure is bonded and cured, the product will produce large thermal stress at high and low temperatures, and the product is prone to brittle cracking, delamination and other undesirable conditions, affecting the functionality of the product.

[0007] 3. Limited scope of application: It can only be applied to specific types of substrates, and its adhesion to certain specific materials (such as glass, Al alloy, etc.) is weak, which limits its versatility and versatility.

[0008] 4. The viscosity is too high, the dispensing construction is difficult, and the glue is not easy to flow out of the dispensing valve.

[0009] 5. Weather resistance problem: Under extreme temperature changes or long-term exposure to outdoor conditions, it will lose its original adhesion; and cannot meet the environmental testing requirements of the product.

[0010] 6. Low initial strength after UV curing: The initial bonding strength of the adhesive is low after UV light exposure. The product cannot be transported for a short period of time, which affects the connection of subsequent processes. Summary of the invention

[0011] The present application is made in view of the above-mentioned problems, and its purpose is to provide a low modulus, high adhesion UV adhesive and its preparation method and application, which can solve at least one technical disadvantage mentioned in the background technology.

[0012] The first aspect of the present application provides a low modulus, high adhesion UV adhesive, comprising the following components in parts by weight: 20-25 parts of polycarbonate polyurethane acrylate resin, 15-20 parts of N,N-dimethylacrylamide, 15-20 parts of hydroxyethyl acrylate, 10-15 parts of tripropylene glycol diacrylate, 1-5 parts of ethoxyethoxyethyl acrylate, 5-10 parts of vinyl chloride and vinyl acetate copolymer resin, 1-5 parts of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 1-5 parts of 2-hydroxy-2-methyl-1-phenyl-1-[4-(2-hydroxyethoxy)phenyl]acetone, 1-2 parts of 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1-2 parts of vinyltriethoxysilane and vinyltrimethoxysilane, 15-30 parts of diluent, and 1-2 parts of defoaming agent.

[0013] In any embodiment, the diluent is one or more of isopropanol, ethanol, n-butanol, ethyl acetate, acetone, and ethylbenzene.

[0014] In any embodiment, the defoaming agent is a complex of dimethylsiloxane, polyoxyethylene polyoxypropanolamine ether, and higher alcohol fatty acid ester.

[0015] Defoaming agents can significantly reduce the surface tension of adhesives, help burst bubbles, eliminate bubbles formed in adhesives, and prevent quality problems of glue during construction.

[0016] The second aspect of the present application also provides a method for preparing a low modulus, high-adhesion UV adhesive, comprising the following steps:

[0017] 1) Raw material mixing: Use a double planetary mixer to add N,N-dimethylacrylamide, hydroxyethyl acrylate, tripropylene glycol diacrylate, and ethoxyethoxyethyl acrylate into a mixer and mix evenly;

[0018] 2) Dispersion and stirring: Use a double planetary disperser to slowly add vinyl chloride and vinyl acetate copolymer resin into the mixer, and stir at the same time until the resin is completely dissolved and becomes a colorless transparent liquid; then add polycarbonate polyurethane acrylate resin, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2-hydroxy-2-methyl-1-phenyl-1-[4-(2-hydroxyethoxy)phenyl]acetone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, vinyl triethoxysilane, vinyl trimethoxysilane, diluent, defoamer, and continue stirring for 1 hour.

[0019] 3) Standing and aging: Standing and aging in a stainless steel container at a constant temperature and away from light for 1-2 days.

[0020] 4) Filtration and impurity removal: Use a filter to filter and make UV adhesive.

[0021] In any embodiment, the constant temperature is 8-18°C.

[0022] In any embodiment, the filter is a stainless steel filter with a pore size of 0.1-3 um.

[0023] The third aspect of the present application also provides a low modulus, high adhesion UV adhesive for use in solder joint protection, prism fixation, glass and plastic bonding, and structural parts bonding.

[0024] Beneficial effects of this application:

[0025] 1. High bonding strength and high initial strength. After being exposed to ultraviolet light, the UV light-curing adhesive can have an initial strength of 0.05-0.2Mpa in 10-20s. It can be fully cured by moisture for 7 days or heating for 1 hour (60-80℃). After curing, it has high bonding strength (PC & glass bonding, shear strength can reach 10.1Mpa). Because of its high adhesion, it can provide better protection for the product and has high vibration resistance, impact resistance, high and low temperature resistance and other characteristics.

[0026] 2. With low modulus of 18.87Mpa, low hardness of 30D, and high elongation of 865%, it can release stress and effectively reduce residual stress in the bonding structure. Avoid cracking, delamination and other phenomena caused by residual stress, which will lead to functional failure of the product.

[0027] 3. It has a wide range of uses and can be used for bonding a variety of different substrates (glass, acrylic, polycarbonate, polyvinyl chloride, aluminum alloy, etc.).

[0028] 4. Moderate viscosity 4233mPa.s and low thixotropic coefficient 2.55, convenient for sizing in the process.

[0029] 5. Good weather resistance, can pass aging test: 125℃ / 1000H high temperature test, hot and cold shock test (-40℃~125℃), temperature cycle test (-40℃~125℃).

[0030] 6. UV adhesives with great performance and price advantages create core market competitiveness for enterprises. DETAILED DESCRIPTION

[0031] The following specifically discloses a low modulus, high-adhesive UV adhesive, a preparation method, and an application embodiment of the present application. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there may be cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structure are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the following description is provided for those skilled in the art to fully understand the present application and is not intended to limit the subject matter described in the claims.

[0032] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0033] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0034] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0035] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0036] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0037] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0038] A low modulus, high adhesion UV adhesive, comprising the following components in parts by weight:

[0039] Polycarbonate type polyurethane acrylate resin (as monomer) 20-25 parts;

[0040] N,N-dimethylacrylamide (as monomer) 15-20 parts;

[0041] Hydroxyethyl acrylate (as monomer) 15-20 parts;

[0042] Tripropylene glycol diacrylate (as monomer) 10-15 parts;

[0043] Ethoxyethoxyethyl acrylate (as monomer) 1-5 parts;

[0044] 5-10 parts of vinyl chloride and vinyl acetate copolymer resin (as copolymer);

[0045] 1-5 parts of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (as a photoinitiator);

[0046] 1-5 parts of 2-hydroxy-2-methyl-1-phenyl-1-[4-(2-hydroxyethoxy)phenyl]acetone (as a photoinitiator);

[0047] 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO for short, as a photoinitiator) 1-2 parts;

[0048] 1-2 parts of vinyltriethoxysilane or vinyltrimethoxysilane (as coupling agent);

[0049] 15-30 parts of diluent, 1-2 parts of defoaming agent.

[0050] The combined use of vinyl chloride and vinyl acetate copolymer resin is to form a vinyl chloride-vinyl acetate copolymer, which is a high molecular compound formed by copolymerization of two monomers, vinyl chloride and vinyl acetate. The specific properties of the copolymer depend on the ratio of vinyl chloride to vinyl acetate and the molecular weight of the copolymer. In this application, the ratio of vinyl chloride: vinyl acetate copolymer resin is 4-5, and the usual ratio is 1:1. The excess of one substance can make the reaction more sufficient and produce a sufficient amount of copolymer. When the proportion of vinyl acetate is high, the copolymer will have better solubility and softness, and is suitable for making coatings and adhesives; and when the proportion of vinyl chloride is high, it is closer to the characteristics of polyvinyl chloride (PVC), and is suitable for making various plastic products, such as films, insulating materials, etc.; the vinyl chloride-vinyl acetate copolymer formed in this application enables the UV adhesive to have good flexibility and low modulus, so that it can reduce the generation of stress in practical applications.

[0051] The combined use of three photoinitiators, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2-hydroxy-2-methyl-1-phenyl-1-[4-(2-hydroxyethoxy)phenyl]acetone and 2,4,6-trimethylbenzoyldiphenylphosphine oxide, provides a better cross-linking reaction for the curing of UV adhesive, increases the reaction points with the substrate, provides good bonding strength, and can greatly increase the UV adhesive under UV light 395nm, 3000mj / cm 3 The initial strength of the solidification during curing under the conditions of 10-20s is 0.05-0.2Mpa, and the subsequent bonding strength is improved. 26 H 22 O3P), 2-hydroxy-2-methyl-1-phenyl-1-[4-(2-hydroxyethoxy)phenyl]propanone (chemical formula C 15 H 14 O4), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (chemical formula C 25 H 20 O3P) are decomposed under ultraviolet light to produce free radicals, triggering polymerization reactions, allowing the resin to cure quickly. The hydroxyl group of 2-hydroxy-2-methyl-1-phenyl-1-[4-(2-hydroxyethoxy)phenyl]acetone can undergo a double esterification reaction with "hydroxyethyl acrylate (as a monomer)", participate in moisture reaction during the UV adhesive curing process, produce a condensation reaction, make up for the easy hydrolysis of the acrylic acid group, and can increase the adhesion and cohesion of the UV adhesive to a certain extent.

[0052] Vinyltriethoxysilane and vinyltrimethoxysilane are selected as coupling agents. The two substances are mixed in the glue and used to participate in hydrolysis and condensation reactions together to form a cross-linked structure; the silanol groups can be further cross-linked through condensation reactions to generate siloxane bonds (Si-O-Si), thereby improving the toughness and cohesion of the glue.

[0053] 1-2 parts of vinyl triethoxysilane (chemical formula CH2=CHSi(OEt)3) and vinyl trimethoxysilane (chemical formula CH2=CHSi(OCH3)3) (as coupling agents), the two substances are mixed in the glue for use; three ethoxy groups and three methoxy groups can form covalent bonds with the surface of 2-hydroxy-2-methyl-1-phenyl-1-[4-(2-hydroxyethoxy)phenyl]acetone after hydrolysis, and the vinyl group participates in the polymerization reaction to establish a strong connection and participates in the condensation reaction to form a cross-linked structure. During the terminal reaction of the glue, the alcohol group is replaced by the hydroxyl group in the water molecule to generate the corresponding silanol group (Si-OH) and the corresponding alcohol (ethanol or methanol), etc. The silanol group can be further cross-linked through the condensation reaction to generate a siloxane bond (Si-O-Si), which greatly improves the toughness, cohesion, and adhesion of the UV adhesive, and the chemical resistance and weather resistance of the UV adhesive are also improved to a certain extent. Vinyl triethoxysilane and vinyl trimethoxysilane are easily soluble in diluents such as ethanol and toluene, which helps to mix the UV adhesive body and facilitates viscosity control.

[0054] When vinyl chloride and vinyl acetate copolymer resin copolymer and vinyl triethoxysilane and vinyl trimethoxysilane coupling agents are added at the same time, the vinyl acetate (C4H6O2) in the vinyl chloride-vinyl acetate copolymer has a long molecular chain and is relatively flexible, with good solubility and softness, and vinyl chloride (C2H3Cl) itself has plasticity and good insulation. In vinyl triethoxysilane and vinyl trimethoxysilane, the vinyl group participates in the polymerization reaction to establish a firm connection, and participates in the condensation reaction together to form a cross-linked structure, so that the UV adhesive has better adhesion. Vinyl triethoxysilane and vinyl trimethoxysilane are easily soluble in diluents such as ethanol and toluene, which is helpful for mixing the UV adhesive body and facilitating the control of viscosity. The molecular density is significantly improved during the cross-linking reaction process in the preparation of the glue, which can enable the UV adhesive to have excellent bonding strength after being fully cured.

[0055] The selection of the ratio and content of the above substances is not isolated, but mutually influential, mutually restricted and coordinated. 14O5), originally added 10-15 parts, using other substances and changing the dosage will change the adhesion and modulus of the UV adhesive of this application; because it has two active acrylate groups, it is easy to undergo free radical polymerization reaction, and will cross-link with the acrylic groups in "hydroxyethyl acrylate (chemical formula C5H8O3)" and "polycarbonate type polyurethane acrylate resin" to form a highly cross-linked polymer network. When "tripropylene glycol diacrylate" is missing or reduced to 0-15 parts, the acrylic groups in hydroxyethyl acrylate and the acrylic groups in polycarbonate type polyurethane acrylate resin become sparse after curing, resulting in a decrease in the adhesion of the UV adhesive and a lower modulus. When "tripropylene glycol diacrylate" is increased to 15-100 parts, due to its acrylate groups Gradually increasing and single chains increasing will make the acrylic groups in UV cross-linked hydroxyethyl acrylate and acrylic groups in polycarbonate type polyurethane acrylate resin become more dense after curing, the adhesion of UV adhesive will decrease, the modulus will increase, and the chemical resistance will deteriorate and become easy to hydrolyze. Similarly, the lack, increase or decrease of "hydroxyethyl acrylate (chemical formula C5H8O3)" and "polycarbonate type polyurethane acrylate resin" will have a great impact on the final modulus and adhesion of UV adhesive. Through continuous DOE tests by experimenters, the best ratio is 20-25 parts of polycarbonate type polyurethane acrylate resin (as monomer), 15-20 parts of hydroxyethyl acrylate (as monomer); 10-15 parts of tripropylene glycol diacrylate (as monomer).

[0056] The technical difficulty of this application is to achieve low modulus and high adhesion of the adhesive at the same time. Low modulus means that the adhesive is very soft, which helps to release stress during the bonding and curing process of structural parts, and also has the effects of impact resistance and creep resistance; high adhesion means that it has better cross-linking with the substrate after curing, is easy to form chemical bonds, and the adhesive itself has strong cohesion; conventional epoxy, acrylic, polyurethane, and bismaleimide in the preparation of existing adhesives usually cannot achieve low modulus, and low modulus silicone rubber itself is biologically inert and chemically inert, and it is not easy to form chemical bonds with most substrates, so its adhesion is poor, and low modulus materials usually have low molecular cross-linking degree and poor medium resistance, which makes it difficult to meet the requirements of forming high adhesion. The present application controls the ratio of "20-25 parts of polycarbonate polyurethane acrylate resin (as monomer), 15-20 parts of hydroxyethyl acrylate (as monomer); 10-15 parts of tripropylene glycol diacrylate (as monomer)." Because the double bonds in the acrylic acid group (-COOCH=CH2) are very active and the molecules have good flexibility, a three-dimensional network structure can be formed after cross-linking, so that the UV adhesive has good flexibility, low modulus and high adhesion; the ester group has a certain polarity and can form hydrogen bonds with water molecules. Therefore, due to the shortcomings of the acrylic acid group's poor chemical resistance and easy hydrolysis, the performance of good stability, strong cohesion, chemical resistance and weather resistance cannot be achieved after UV curing.

[0057] And by adding 1-5 parts of 2-hydroxy-2-methyl-1-phenyl-1-[4-(2-hydroxyethoxy)phenyl]acetone (as a photoinitiator), the structure of which includes hydroxyl (—OH), methyl (—CH3), phenyl (—C6H5) and phenyl with hydroxyethoxy (—OCH2CH2OH) substituents; the hydroxyl group can undergo a double esterification reaction with "hydroxyethyl acrylate (as a monomer)", participate in the moisture reaction during the curing process of the UV adhesive, produce a condensation reaction, compensate for the easy hydrolysis of the acrylic acid group, and can increase the adhesion and cohesion of the UV adhesive to a certain extent.

[0058] At the same time, by adding 1-2 parts of vinyl triethoxysilane (chemical formula CH2=CHSi(OEt)3) and vinyl trimethoxysilane (chemical formula CH2=CHSi(OCH3)3) (as coupling agents), the two substances are mixed in the glue for use; the three ethoxy groups and three methoxy groups can form covalent bonds with the surface of 2-hydroxy-2-methyl-1-phenyl-1-[4-(2-hydroxyethoxy)phenyl]acetone after hydrolysis, and the vinyl groups participate in the polymerization reaction to establish a strong connection and participate in the condensation reaction to form a cross-linked structure. The silanol groups can be further cross-linked through the condensation reaction to form siloxane bonds (Si–O–Si), which greatly improves the toughness, cohesion, and adhesion of the UV adhesive, and the chemical resistance and weather resistance of the UV adhesive are also improved to a certain extent. Vinyl triethoxysilane and vinyl trimethoxysilane are easily soluble in diluents such as ethanol and toluene, which helps to mix the UV adhesive body and facilitates the control of viscosity.

[0059] In any embodiment, the diluent is one or more of isopropanol, ethanol, n-butanol, ethyl acetate, acetone, and ethylbenzene.

[0060] In any embodiment, the defoaming agent is a complex of dimethylsiloxane, polyoxyethylene polyoxypropanolamine ether, and higher alcohol fatty acid ester.

[0061] The key to the present application is to first use a combination of photosensitive groups bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2-hydroxy-2-methyl-1-phenyl-1-[4-(2-hydroxyethoxy)phenyl]acetone, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide as a photoreaction participating in the light irradiation process, at 395nm spectrum, 3000mj / cm 3It can be quickly cured and shaped under the light conditions, and has a high initial strength, which not only gives the sealant excellent flexibility and high bonding strength, but also has good high and low temperature resistance, chemical resistance and low moisture permeability, and can achieve an initial solid strength of 0.05-0.2Mpa within 10-20s; because under the above-mentioned light conditions, the photosensitive groups in the photoinitiator containing bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2-hydroxy-2-methyl-1-phenyl-1-[4-(2-hydroxyethoxy)phenyl]acetone, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide are rapidly polymerized, the bonding strength of the UV adhesive rises sharply, and the initial bonding force to the substrate is generated, resulting in a shaping effect, and can resist the influence of slight external forces; After the light stops, the adhesive continues to cure by moisture curing. The monomers tripropylene glycol diacrylate with two active acrylate groups and N,N-dimethylacrylamide containing one acrylamide group cross-link with ethoxyethoxyethyl acrylate and hydroxyethyl acrylate monomers under the action of moisture to form long-chain, network or tree-like structures, which further improve the adhesion, flexibility and other properties of the adhesive. Compared with the urethane bond after isocyanate moisture curing, the siloxane bond (Si-O-Si) of vinyl triethoxysilane and vinyl trimethoxysilane has good chemical stability, which brings more elasticity to the adhesive system, greatly improves the toughness, cohesion and adhesion of the UV adhesive, and the chemical resistance and weather resistance of the UV adhesive are also improved to a certain extent. In the reaction, the resin raw materials of vinyl chloride and vinyl acetate copolymer resin coupling agent mainly provide the adhesive itself with adhesion, toughness, and inherent characteristics, improve the cohesion and adhesion of the adhesive, and improve the mechanical properties; the monomers mainly participate in the cross-linking reaction to form long chains, mesh or tree structures, which can control the curing process, hardness, heat resistance, and chemical resistance; among them, ethoxyethoxyethyl acrylate monomer mainly provides good chemical resistance and water resistance. The monomer tripropylene glycol diacrylate mainly improves adhesion, has two active acrylate groups, and is easy to undergo free radical polymerization to form a highly cross-linked polymer network. The hydroxyethyl acrylate monomer is copolymerized with other monomers to achieve the desired viscosity, cohesion, and adhesion. The monomer N,N-dimethylacrylamide contains an acrylamide group, which is copolymerized with the monomers ethyl acrylate, ethoxyethoxyethyl acrylate, and tripropylene glycol diacrylate to form a polymer through free radical polymerization. Diluents are further used to change the viscosity for ease of construction and to control the solid content of the adhesive to a certain extent. Defoaming agents are used to significantly reduce the surface tension of the adhesive, help burst bubbles, and improve the use effect.

[0062] Example

[0063] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If no specific techniques or conditions are indicated in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0064] Example 1

[0065] A method for preparing a low modulus, high-adhesion UV adhesive comprises the following steps:

[0066] 1) Raw material mixing: Use a double planetary mixer to add 16 kg of N,N-dimethylacrylamide, 15 kg of hydroxyethyl acrylate, 10 kg of tripropylene glycol diacrylate, and 1 kg of ethoxyethoxyethyl acrylate into a mixer and mix well;

[0067] 2) Dispersion and stirring: Use a double planetary disperser to slowly add 5 kg of vinyl chloride and vinyl acetate copolymer resin into the mixer, and stir at the same time until the resin is completely dissolved and becomes a colorless transparent liquid; then add 20 kg of polycarbonate polyurethane acrylate resin, 2 kg of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 3 kg of 2-hydroxy-2-methyl-1-phenyl-1-[4-(2-hydroxyethoxy)phenyl]acetone, 1 kg of 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2 kg of vinyl triethoxysilane and vinyl trimethoxysilane, 25 kg of isopropanol, and 1 kg of dimethylsiloxane, and continue stirring for 1 hour.

[0068] 3) Standing and aging: Standing and aging in a stainless steel container at a constant temperature of 8°C and away from light for 1-2 days;

[0069] 4) Filtration and impurity removal: Use a 0.1um stainless steel filter to filter and make UV adhesive.

[0070] Example 2

[0071] A method for preparing a low modulus, high-adhesion UV adhesive comprises the following steps:

[0072] 1) Raw material mixing: Use a double planetary mixer to add 17 kg of N,N-dimethylacrylamide, 17 kg of hydroxyethyl acrylate, 12 kg of tripropylene glycol diacrylate, and 1 kg of ethoxyethoxyethyl acrylate into a mixer and mix well;

[0073] 2) Dispersion and stirring: Use a double planetary disperser to slowly add 6 kg of vinyl chloride and vinyl acetate copolymer resin into the mixer and stir at the same time until the resin is completely dissolved and becomes a colorless transparent liquid; then add 22 kg of polycarbonate polyurethane acrylate resin, 3 kg of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 3 kg of 2-hydroxy-2-methyl-1-phenyl-1-[4-(2-hydroxyethoxy)phenyl]acetone, 1 kg of 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1 kg of vinyl triethoxysilane and vinyl trimethoxysilane, 23 kg of isopropanol, and 2 kg of dimethylsiloxane, and continue stirring for 1 hour.

[0074] 3) Standing and aging: Standing and aging in a stainless steel container at a constant temperature of 15°C and away from light for 1-2 days;

[0075] 4) Filtration and impurity removal: Use a 1um stainless steel filter to filter and make UV adhesive.

[0076] Example 3

[0077] A method for preparing a low modulus, high-adhesion UV adhesive comprises the following steps:

[0078] 1) Raw material mixing: Use a double planetary mixer to add 15 kg of N,N-dimethylacrylamide, 15 kg of hydroxyethyl acrylate, 10 kg of tripropylene glycol diacrylate, and 5 kg of ethoxyethoxyethyl acrylate into a mixer and mix well;

[0079] 2) Dispersion and stirring: Use a double planetary disperser to slowly add 7 kg of vinyl chloride and vinyl acetate copolymer resin into the mixer and stir at the same time until the resin is completely dissolved and becomes a colorless transparent liquid; then add 23 kg of polycarbonate polyurethane acrylate resin, 4 kg of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 3 kg of 2-hydroxy-2-methyl-1-phenyl-1-[4-(2-hydroxyethoxy)phenyl]acetone, 1 kg of 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1 kg of vinyl triethoxysilane and vinyl trimethoxysilane, 15 kg of isopropyl alcohol, and 1 kg of dimethylsiloxane, and continue stirring for 1 hour.

[0080] 3) Standing and aging: Standing and aging in a stainless steel container at a constant temperature of 18°C ​​and away from light for 1-2 days;

[0081] 4) Filtration and impurity removal: Use a 3um stainless steel filter to filter and make UV adhesive.

[0082] The test method of the properties of UV adhesive before curing was prepared through the above embodiment:

[0083] (1) Density test: Accurately weigh a certain amount of adhesive sample, using the ASTM D1475 method, place the sample in a desiccator to remove the solvent, and re-weigh the sample after drying.

[0084] (2) Viscosity test: Use a rotary viscosity tester, adopt ASTM D7042 method, select conical rotor Spindle 18, rotate at 10 RPM, and start the viscometer.

[0085] (3) Thixotropy test: Place the adhesive in a sample cup and perform a pre-shear treatment for 1 minute at a shear rate of 100 RPM using the ASTM D6923 method. Then, reduce the shear rate to 1 RPM and continue measuring for 5 minutes.

[0086] (4) Contact angle test: Use a contact angle meter to drop a drop of glue onto a clean glass substrate and observe the contact angle result using the GB_T 30693-2014 method.

[0087] The test method for the properties of UV adhesive after curing was prepared through the above embodiment. The data after curing by dispensing glue on a PC & glass flat plate (20×20mm) are as follows:

[0088] (1) Curing method: In a dust-free and light-free environment, use an LED lamp with a wavelength of 395nm and an energy density of 3000mJ / cm3 for irradiation curing for 10s and moisture curing for 3 days.

[0089] (2) Shear strength test: Take an appropriate amount of cured samples and use a universal tensile testing machine with a speed set to 5 mm / min. Use the ASTM D3528 method to test the samples after UV initial curing and the samples after UV + moisture curing for 3 days.

[0090] (3) Hardness test: Take an appropriate amount of cured samples and use a Shore hardness tester to perform a hardness test on the samples after UV+humidity curing for 3 days using the ASTM D2240 method.

[0091] (4) Tensile strength and elongation at break: Take an appropriate amount of cured samples and use a universal tensile testing machine with a speed set to 50 mm / min. Fix the samples in the fixture to ensure that the center of the sample is located on the center line of the fixture. Use the ASTM D412 method to perform a hardness test on the samples after UV+humidity curing for 3 days.

[0092] The contact angle of the UV adhesive prepared by the above method is as shown in Table 1:

[0093]

[0094] Table 1

[0095] The relationship between the time and initial strength of the adhesive after UV curing is shown in Table 2:

[0096]

[0097]

[0098] Table 2

[0099] The technical parameters of the UV adhesive prepared by the above method and corresponding to each embodiment are shown in Table 3 below:

[0100]

[0101]

[0102] Table 3

[0103] In summary, Example 1 is a better mixing method.

[0104] The UV adhesive prepared by the above method was cured after being dispensed on a PC & glass flat plate (20×20 mm). The test results of the embodiment are shown in Table 4 below:

[0105]

[0106] Table 4

[0107] The present application controls the comparative experiment of vinyl chloride and vinyl acetate copolymer resin materials, and the weight ratio of the added materials is as shown in Table 5 below:

[0108]

[0109]

[0110] Table 5

[0111] In a dust-free and light-free environment, glue was dispensed on a PC & glass flat plate (20×20mm) using a glue dispenser. The LED light with a wavelength of 395nm and an energy density of 3000mJ / cm3 was used for irradiation and curing for 10s, and moisture curing for 3 days. The data is shown in Table 6 below:

[0112]

[0113] Table 6

[0114] From the above experimental data, it can be concluded that when no vinyl chloride-vinyl acetate copolymer is added, the modulus of the UV adhesive becomes significantly larger and the adhesion decreases; when 1 part of vinyl chloride and 9 parts of vinyl acetate are added, the hardness becomes lower and its adhesion (shear strength) decreases significantly; when 9 parts of vinyl chloride and 1 part of vinyl acetate are added, the hardness becomes significantly larger, its adhesion (shear strength) decreases significantly, the volume resistivity increases, and the overall insulating plasticity is present.

[0115] The adhesive prepared in this application has the following characteristics:

[0116] 1. The UV light-curing adhesive has high bonding strength (PC & glass bonding, shear strength can reach 10.1Mpa). Due to its high adhesion, it can provide better protection for the product and has high vibration resistance, impact resistance, high and low temperature resistance and other characteristics.

[0117] 2. With low modulus of 18.87Mpa, low hardness of 30D, and high elongation of 865%, it can release stress and effectively reduce residual stress in the bonding structure. Avoid cracking, delamination and other phenomena caused by residual stress, which will lead to functional failure of the product.

[0118] 3. It has a wide range of uses and can be used for bonding a variety of different substrates (glass, acrylic, polycarbonate, polyvinyl chloride, aluminum alloy, etc.).

[0119] 4. Moderate viscosity 4233mPa.s and low thixotropic coefficient 2.55, convenient for sizing in the process.

[0120] 5. Good weather resistance, can pass aging test: high temperature resistance test, hot and cold shock test, temperature cycle test.

[0121] 6. UV adhesives with great performance and price advantages create core market competitiveness for enterprises.

[0122] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the main purpose of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A low modulus, high adhesion UV adhesive, characterized in that: The invention comprises the following components in parts by weight: 20-25 parts of polycarbonate type polyurethane acrylate resin, 15-20 parts of N,N-dimethylacrylamide, 15-20 parts of hydroxyethyl acrylate, 10-15 parts of tripropylene glycol diacrylate, 1-5 parts of ethoxyethoxyethyl acrylate, 5-10 parts of vinyl chloride and vinyl acetate copolymer resin, 1-5 parts of bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 1-5 parts of 2-hydroxy-2-methyl-1-phenyl-1-[4-(2-hydroxyethoxy)phenyl]acetone, 1-2 parts of 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 1-2 parts of vinyltriethoxysilane and vinyltrimethoxysilane, 15-30 parts of diluent and 1-2 parts of defoaming agent.

2. The UV adhesive according to claim 1, characterized in that: The diluent is one or more of isopropanol, ethanol, n-butanol, ethyl acetate, acetone, and ethylbenzene.

3. The UV adhesive according to claim 1, characterized in that: The defoaming agent is a compound of dimethylsiloxane, polyoxyethylene polyoxypropanolamine ether and high-carbon alcohol fatty acid ester.

4. A method for preparing a low modulus, high adhesion UV adhesive, comprising the following steps: 1) Raw material mixing: Use a double planetary mixer to add N,N-dimethylacrylamide, hydroxyethyl acrylate, tripropylene glycol diacrylate, and ethoxyethoxyethyl acrylate into a mixer and mix evenly; 2) Dispersion and stirring: Use a double planetary disperser to slowly add vinyl chloride and vinyl acetate copolymer resin into the mixer, and stir at the same time until the resin is completely dissolved and becomes a colorless transparent liquid; then add polycarbonate polyurethane acrylate resin, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2-hydroxy-2-methyl-1-phenyl-1-[4-(2-hydroxyethoxy)phenyl]acetone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, vinyl triethoxysilane, vinyl trimethoxysilane, diluent, and defoamer, and continue stirring for 1 hour. 3) Standing and aging: Standing and aging in a stainless steel container at a constant temperature and away from light for 1-2 days; 4) Filtration and impurity removal: Use a filter to filter and make UV adhesive.

5. The method for preparing the UV adhesive according to claim 4, characterized in that: The constant temperature is 8-18°C.

6. The method for preparing the UV adhesive according to claim 4, characterized in that: The filter is a stainless steel filter with a pore size of 0.1-3 um.

7. Use of the adhesive according to any one of claims 1 to 3 or the adhesive obtained by the preparation method according to any one of claims 4 to 6 in solder joint protection, prism fixing, glass and plastic bonding, and structural parts bonding.

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