CN102079961B - Ultraviolet curing adhesive - Google Patents

Abstract

An ultraviolet light curing adhesive is composed of a resin main body, a solvent, an ultraviolet photoinitiator and an auxiliary agent. The resin main body consists of resin R and resin H. The main chain of R resin contains polyether structure, and the branch chain contains vinyl light. Active group, active polyurethane acrylic resin with low molecular weight, H resin is an inert polyurethane acrylic resin with polydiene and aromatic ether structure in the main chain and relatively high molecular weight. The adhesive does not contain monomers or prepolymers, has a high softening point, can be pre-coated on the substrate, has super strong adhesion to high oily contact surfaces, and has high temperature resistance, small internal stress, and good flexibility features.

Description

A UV curing adhesive

technical field

The invention belongs to the technical field of flexible resin plates, and in particular relates to an ultraviolet light curing adhesive.

Background technique

In recent years, flexible photosensitive resin plates have been widely used in the printing of cartons, flexible packaging, labels and other deformable or soft substrates due to the advantages of water-based inks, environmental protection, wide range of printing materials, high printing durability, and simple and easy combination of printing machines. At present, foreign flexible photosensitive resin plate technology has matured, and many large foreign companies such as DuPont, Asahi Kasei, Medellin, Flint, etc. have launched products. In China, only Lucky Erjiao has launched products and has mass-produced them. The development of flexible photosensitive resin plates has always been a hot spot in the development of printing plates in the world.

Usually, the structure of the flexible photosensitive resin plate is the substrate, the adhesive layer, the elastomer and the protective film from bottom to top. The role of the adhesive layer is to firmly fix the photosensitive elastomer on the substrate, to ensure that the size of the elastomer is stable, and the graphics and texts are not deformed; to ensure that the elastomer and the substrate will not be damaged by strong shearing force and peeling force during printing. Peel off and fall off.

To produce qualified flexographic products, the adhesive layer must solve the following main problems:

1. High oily interface bonding problem: During the production of flexographic plates, in order to facilitate the full mixing of elastomers, more than 20% of a large amount of butyl oil, naphthenic oil, silicone oil and other oils are added to the elastomer layer, resulting in high oily elastomers. Difficult to connect.

2. The problem of flexibility matching between the elastomer, the adhesive layer and the substrate: After the flexographic plate is exposed, the elastomer, the adhesive layer, and the substrate should have a certain degree of flexibility, and there will be no cracks when curling at a minimum of minus 30°C. No deformation, no falling off.

3. The problem of initial adhesion: during the production of flexographic plates, there must be a certain initial adhesion between the unexposed plate, the elastomer and the base material, so as to ensure that the plate is in the process of cutting, inspection, packaging, transportation, etc. Problems such as deformation and falling off occur.

4. The problem of internal stress after UV curing: After the plate is exposed to ultraviolet light during plate making, the adhesive is cross-linked and must shrink to generate internal stress. It is necessary to solve the problem of curling, deformation, and bonding of the plate caused by the internal stress shrinkage of the long-term UV exposure The force drops sharply or even falls off.

5. Adhesion problem in the printing process: After the plate is exposed to ultraviolet rays, it should produce a strong adhesive force. The prepared plate is fixed on the roller of the flexo printing machine, which can resist the strong shear force and peeling force during printing. , to ensure that the elastomer and the substrate do not peel off.

6. The problem of high temperature resistance of the adhesive: during the production of flexographic plates, the mixing temperature of the elastomer is 100-130 degrees, and the problem of high temperature resistance of the adhesive should be solved.

7. Coating process issues: In order to reduce the variable factors of flexographic plate production, the adhesive should be pre-coated on the substrate for later use. The softening point of the adhesive should be much higher than room temperature, and it will not stick to hands after drying. It can be stored in rolls, and has the ability of anti-compression and non-adhesion.

8. Stability issues: substrate pre-coating and production plates should have 18-month quality stability.

In order to solve this problem, Mitsui Chemicals JP01115/2000 introduced a kind of thermosetting polyurethane resin, but the flexibility is too poor, and it is easy to crack and cause the elastomer and the base material to fall off; The bonding operation is complicated; U.S. Patent No. 4,917,990 discloses coating an adhesive layer containing chlorosulfonated polyethylene, but the adhesive force will decrease with the increase of exposure. A moisture-cured layer is introduced in JP-A-2000-155410, which is difficult to industrialize; European Patent EP1209524A1 discloses that a solution containing polyol and diisocyanate is coated on a substrate, but the curing time is long and industrial implementation is difficult; WO2004/092841 discloses a direct The method of using double-sided adhesive bonding, but the error is large and the operation is difficult.

Contents of the invention

The object of the present invention is to solve the above-mentioned problems in the prior art, and provide an ultraviolet curing adhesive used in the production of flexible resin plates.

To achieve the above object, the present invention adopts the following technical solutions:

The ultraviolet curing adhesive of the present invention is composed of a resin body, a solvent, an ultraviolet photoinitiator and an auxiliary agent. Composition of inert polyurethane acrylic resin H, the weight ratio of resin R to resin H in the adhesive is 1:10-10:1.

The resin matrix of the resin R is obtained through the polymerization reaction of diisocyanate and dihydroxy compound, and the dihydroxy compound includes polyether diol and carboxyl-containing dihydroxy compound, and the terminal active-NCO is blocked with low molecular weight alcohol; The photoactive group is obtained by grafting vinyl compounds through branched carboxyl ring opening and condensation reaction. The weight average molecular weight of the resin R is 4000-100000, the acid value Av<20mgKOH/g resin, the iodine value Iv=20-100gI2/100g resin.

The diisocyanate is at least one of aromatic diisocyanate, aliphatic diisocyanate and alicyclic diisocyanate.

The diisocyanate is preferably a mixture of dicyclohexylmethane diisocyanate and hexamethylene diisocyanate, and the mass ratio of dicyclohexylmethane diisocyanate to hexamethylene diisocyanate is 100:1-1:100.

The polyether diol, its main chain structure contains at least HO-[CH2-CH(-R)-O-]n-OH segment, where -R represents a hydrogen atom or a branched methyl group, and n is 3 -200 integer, the mass percent content of polyether diol in the dihydroxy compound is 1-50%.

The polyether diol is preferably one of triethylene glycol, polytetramethylene glycol ether polyol, polytetrahydrofuran polyol, polypropylene oxide polyol, polybutylene oxide polyol or polyoxypropylene glycol One, the mass percent content of polyether diol in the dihydroxy compound is preferably 10-30%.

The carboxyl-containing dihydroxy compound is 2,2-bismethylolpropionic acid or 3,5-dihydroxybenzoic acid, and the mass percentage content of the carboxyl-containing dihydroxy compound in the dihydroxy compound is 50-99%.

The vinyl graft compound is 3,4-epoxycyclohexyl acrylate or glycidyl methacrylate or a combination of the two, and the molar ratio of the vinyl graft compound to the carboxyl-containing dihydroxy compound is 0.8:1- 1.5:1.

The resin H is obtained through the polymerization reaction of diisocyanate, hydroxyl-terminated polydiene compound and at least one aromatic ether chain extender. The active end-NCO is blocked with low-molecular alcohol, and the weight-average molecular weight of the resin is 5,000-200,000. Acid value Av=10-150mgKOH/g resin.

The diisocyanate is at least one of aromatic diisocyanate, aliphatic diisocyanate and alicyclic diisocyanate.

The diisocyanate is preferably cyclohexylmethane diisocyanate.

The hydroxyl-terminated diene compound contains a repeating segment HO-[(CH2-CR=CH-CH2)y(CH2-CHCN)x]n-OH, wherein R is a hydrogen atom or a branched methyl group, and x= 0, y=1, n is a positive integer of 1-200.

The hydroxyl-terminated diene compound contains a repeating segment HO-[(CH2-CR=CH-CH2)y(CH2-CHCN)x]n-OH, wherein R is a hydrogen atom or a branched methyl group, x= 1, y=1-10, n is a positive integer of 1-200.

The method of synthesizing the above R resin is to first synthesize the resin matrix, which is obtained by hydrogen transfer addition polymerization of diisocyanate, branched carboxyl dihydroxy compound and polyether diol, and the terminal active-NCO is blocked by low molecular alcohol The terminal group and the branched chain photoactive group are obtained by grafting the epoxy monomer containing unsaturated double bonds and the branched chain containing carboxyl group for ring opening and condensation reaction.

The method for synthesizing the above-mentioned H resin is obtained by hydrogen transfer addition polymerization of diisocyanate with rigid structure, hydroxyl-terminated polydiene, and chain extender, and the terminal active-NCO is blocked with low-molecular-weight alcohol.

Contain ultraviolet photoinitiator in the bonding agent of the present invention, the ultraviolet photoinitiator that can add has benzophenone, michrone, 4-acetoxy group-4'-diethylamine benzophenone, Benzoin ethyl ether, α-hydroxyisopropylbenzophenone, α-hydroxycyclohexylbenzophenone, 2-phenyl-2,2-dimethoxyacetophenone, 2-tert-butylanthraquinone, isopropyl Thioxanthraquinone, (morpholinobenzoyl) 1-hexyl 1,1 (dimethylamino) propane, benzil, benzoin, etc., the added amount accounts for 0.2-2% of the total solids.

The solvent used for preparing the adhesive of the present invention can be alcohol solvents, ketone solvents, hydrocarbon solvents, amide solvents, ether solvents, lipid solvents, diol derivative solvents, etc., such as methanol, ethanol, acetone , butanone, cyclohexanone, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dichloromethane, benzene, toluene, ethyl acetate, ethylene glycol mono Methyl ether, ethylene glycol monoethyl ether, etc. The solid content of the binder of the present invention is 0.5-20%.

Adjuvants such as UV absorbers, anti-halation dyes, pigments, heat stabilizers, and oxygen scavenger can also be added to the adhesive. The amount added accounts for 0.2-5% of the total solids.

Owing to adopting above-mentioned technical scheme, the present invention has solved following technical problem:

1. The adhesive adopts ultraviolet light curing technology, and the adhesive is composed of two kinds of polyurethane acrylic resins, R and H, and a small amount of ultraviolet photoinitiator and auxiliary agent. R resin is an active polyurethane acrylic resin containing polyether structural units with low softening point and molecular weight, and H resin is an inert polyurethane acrylic resin with a relatively high molecular weight main chain having polydiene and aromatic ether structures.

2. In order to solve the problem of high oily interface bonding, the main chain of the active component R resin component of the adhesive is introduced into a polyether segment, and the inert component H contains a similar segment of polydiene elastomer.

3. In order to solve the matching problem between the elastomer, the adhesive layer and the substrate, the main chain of the resin component of the adhesive H resin is introduced into a polydiene structural unit, which is combined with the block polydiene elastomer and the substrate vinylidene chloride The flexibility and compatibility of the bottom layer are very good.

4. Solve the problem of unexposed initial adhesion: the adhesive does not contain monomers or oligomers, which greatly improves the softening point. The design and elastomer, the substrate has a similar structure to the polymer, and the adhesive has a certain initial adhesion without exposure. Adhesive force to ensure that the plate will not be deformed or peeled off during the process of cutting, plate inspection, packaging, and transportation.

5. Adhesion problem in the printing process: the adhesive contains a kind of R resin, and its branch chain contains at least one (meth)acryloyloxy photoactive group, which will produce super adhesive force after ultraviolet curing, which can Ensure that the elastic body and the substrate will not be deformed or peeled off due to the strong shear force during printing.

6. The problem of high temperature resistance of the adhesive: the main chain of the adhesive resin is designed with a polyether and a special polydiene high temperature resistant unit, and the chain extender also uses an aromatic diether high temperature resistant unit.

7. Coating process issues: the adhesive does not contain monomers or oligomers, the substrate does not stick after drying, the soft segment of polyether and polydiene has good flexibility, and the substrate can be curled and collected with high curvature after coating The roll is ready for use, and the adhesive has good low temperature resistance, high temperature resistance and good storage stability in the later period.

8. Combined resin technology: Adjusting the content of inert H resin can combine different maximum exposure times, reduce the internal stress damage of UV curing, and adapt to the production needs of different types of flexographic plates.

The UV-curable adhesive prepared by the invention has super-strong adhesion to high-oily contact surfaces, good flexibility at low temperature, high-temperature resistance and ultraviolet-ray cracking ability, easy coating and storage, and fully meets the industrial production of flexible resin plates. Various performance needs. The adhesive does not contain viscous prepolymers, has a high softening point, and can be pre-coated on the substrate; the film has good flexibility, and the substrate can be curled and rolled up after coating; it has good contact with high oily elastomers Super strong adhesion on the surface; high initial adhesion before UV exposure, ensuring no air bubbles between the elastomer and the substrate during production, no deformation and no falling off during cutting; after exposure to the UV back of the plate, it can produce strong adhesion Relay, and has good flexibility, to ensure that the elastomer and the substrate will not be deformed or peeled off due to the strong shear force during printing; it has good resistance to ultraviolet damage, and the adhesion will not increase with the amount of exposure There is a decline; it has the ability to resist high temperature damage.

Detailed ways

The invention provides a synthetic method for preparing an ultraviolet curing adhesive and its main components used in the production of flexible resin plates. Specifically, the adhesive adopts polyurethane acrylate resin UV curing technology. The main body of the adhesive is a polyurethane acrylic resin composition and a small amount of ultraviolet photoinitiator and auxiliary agent. One of the R resins contains a polyether structure in the main chain. Active polyurethane acrylic resin with low softening point and molecular weight, its branch chain contains at least (meth)acryloxy photoactive group, its function is to replace the prepolymer, through the ultraviolet back exposure of the flexible resin plate in the later stage of plate making. Light curing to produce super adhesive force. Another kind of H resin main chain contains polydiene and aryl diether structure, relatively high molecular weight inert polyurethane acrylic resin, its function is to provide high temperature resistance adhesion and good plate compatibility for flexible plates.

The following is a detailed description of the present invention.

1. First synthesize the R resin component in the present invention.

First, the R resin component of the present invention will be described.

The UV curing component R resin is designed in the adhesive, the main chain contains polyether units, and its branches contain (meth)acryloxy photoactive groups.

The method for synthesizing the above-mentioned R resin firstly synthesizes the R resin matrix, and then grafts active groups, and the reaction is completed by a one-step method or a two-step method.

First, the R resin matrix is synthesized. The R resin matrix is obtained by hydrogen transfer addition polymerization of diisocyanate, branched dihydroxy compound containing carboxyl groups, and polyether diol. The terminal active-NCO is blocked with low molecular weight alcohol.

The diisocyanates used for synthesizing the R resin matrix of the present invention include 2,4-toluene diisocyanate (2,4--TDI), 2,6-toluene diisocyanate (2,6-TDI) and their mixtures in detail, 4, 4'-Diphenylmethane diisocyanate (MDI), 3,3'-dimethyl 4,4'-dicyclohexylmethane diisocyanate (DDI), 2,2,4-TMDI isophorone diisocyanate ( IPDI), 4,4'-dicyclohexylmethane diisocyanate (H12MDI), xylylene diisocyanate (XDI), tetramethyl xylylene diisocyanate (TMXDI), 1,5-naphthalene diisocyanate (NDI), 1,6-hexylene diisocyanate (1,6-HDI), 4,6-xylene diisocyanate (4,6-XDI), phenylene-p-diisocyanate (PPDI), 2,2,4-trimethyl Base-1,6-hexamethylene diisocyanate (TMDI) and so on. Considering the film color, adhesion and flexibility of the adhesive, it is best to use HMDI and HDI. The resin synthesized by the combination of the two will not yellow, have high transparency, and good flexibility. The mass ratio of HMDI/HDI is within the range of HMDI/HDI. =100/1-1/100, the optimal range is 90/10-70/30.

The dihydroxy compound used for synthesizing the R resin matrix of the present invention includes polyether diol and carboxyl-containing dihydroxy compound.

In order to increase the oil resistance and tear resistance of the adhesive, the R resin chain segment is added with polyether structural units. The R resin of the present invention can be added with polyether structural units including triethylene glycol, polybutylene glycol ether polyol (PBD), Polytetrahydrofuran polyol (PTMEG), polypropylene oxide polyol (PPO), polybutylene oxide polyol (PBO), polyoxypropylene glycol (PPG), etc. It is best to add triethylene glycol (TEG) or polyoxypropylene glycol (PPG), and the content of triethylene glycol (TEG) or polyoxypropylene glycol (PPG) in the mass percentage of the dihydroxy compound is 1-50%, the best The ratio is 10-30%.

To synthesize the R resin matrix of the present invention, it is necessary to add a carboxyl-containing dihydroxy compound, and the carboxyl group is the bridge for grafting active groups in the next step, so the carboxyl-containing dihydroxy compound is also one of the necessary components, such as 2,2-dihydroxy Methylpropionic acid, 3,5-dihydroxybenzoic acid, etc. It is best to use DMPA, which has a small molecular weight and a high carboxyl contribution rate, and it is also a good chain extender. The amount of DMPA accounts for 50-99% of the mass percentage of dihydroxy compounds, and the best ratio is 70% -90%.

In order to make the R resin have good stability, it is necessary to block the active-NCO at the end group of the R resin matrix. The active-NCO at the end group of the R resin matrix is blocked with low-molecular alcohols, such as butanol, ethanol, methanol, etc., preferably methanol Blocking end groups. The dosage is 1%-20% of the moles of diisocyanate, and the optimal ratio is 1%-10%.

The reaction temperature for synthesizing the R resin matrix of the present invention is 40-140°C, preferably 50-100°C.

Synthesizing the present invention synthesizing the catalyzer of the present invention's R resin precursor is as butyl lead, stannous octoate, dibutyltin dilaurate, N-methylmorpholine, piperazine, trialkylphosphine, strong base, basic salt , cobalt, iron, tertiary amine, etc. can be used as the matrix resin synthesis catalyst, preferably dibutyltin dilaurate, the dosage is 0.01-10% of the monomer fed, and the optimal amount is 0.1-5%.

The solvent for synthesizing the R resin matrix of the present invention must be a solvent that does not contain active hydrogen (including water in the solvent), such as dried N,N-dimethylformamide, N,N-dimethylacetamide, toluene, Methyl ethyl ketone, dioxane, etc., or a mixture thereof. It is best to use polyurethane grade N,N-dimethylformamide (DMF) or N,N-dimethylacetamide (DMAC).

The solid content of the reaction for synthesizing the R resin matrix of the present invention is 10-80%, preferably 20-70%.

The weight-average molecular weight of the synthetic R resin matrix of the present invention is 2000-100000, preferably 3000-50000, and the acid value is 20-200 mgKOH/g resin, preferably 50-150 mgKOH/g resin.

The branched chain of R resin containing photoactive groups is obtained by grafting the epoxy monomer containing acryloyloxy unsaturated double bond with the branched chain containing carboxyl group and condensation reaction.

The unsaturated epoxy monomer grafted to the R resin matrix is preferably CMA (3,4-epoxycyclohexyl acrylate) or GMA (glycidyl methacrylate) or a combination of the two. The molar ratio of unsaturated epoxy monomer to carboxyl dihydroxy compound is 0.8:1-1.5:1, preferably 1:1-1.2:1.

The grafting reaction temperature is 50-150°C, preferably 80-120°C.

R resin matrix grafting reaction catalysts are inorganic acids, alkalis, amines, quaternary ammonium bases, quaternary ammonium salts and the like.

R resin matrix graft reaction polymerization inhibitors include hydroquinone HQ, p-benzoquinone PBQ, methylhydroquinone THQ, p-hydroxyanisole HQMME, 2-tert-butylhydroquinone MTBHQ, 2,5- Di-tert-butyl hydroquinone, nitroxide free radical piperidinol (ZJ-701), etc. It is better to use nitroxide free radical piperidinol (ZJ-701), which has less toxicity, good effect of high-temperature grafting polymerization inhibition, easy removal of by-products, less residual color of resin, and does not affect the late-stage UV polymerization of the adhesive.

Synthetic R resin of the present invention preferably adopts following post-treatment process:

After the reaction is completed, the solution is cooled and diluted. The diluted solvents include acetone, methyl ethyl ketone, cyclohexanone, pyrrolidone, N-methylpyrrolidone, ethyl acetate, tetrahydrofuran, methanol, dioxane, etc. The dilution ratio should be well controlled. The solid content is the control index. If the solid content is too low, the resin is easy to emulsify in water, which affects the resin yield. If the solid content is too high, the resin is easy to agglomerate and cannot be dispersed into crisp grains. The synthesis of the R resin of the present invention is best to use dioxygen Hexacyclic as a diluting solvent, the dilution ratio is 1%-50% of the solid content, and the best ratio is 5%-30%.

The diluted reaction liquid is dropped into deionized water to precipitate. It is better to add a small amount of inorganic or organic acid in deionized water. products, making the resin performance more stable. The inorganic or organic acids that can be used include dilute sulfuric acid, phosphoric acid, dilute hydrochloric acid, glacial acetic acid, etc. Glacial acetic acid is the best choice, which is relatively weak in corrosion and easy to handle.

R resin is washed and then dried. The temperature is controlled at 20°C-70°C, preferably at 30-50°C. It can be dried in vacuum, blown air or naturally at room temperature.

Synthesize the weight-average molecular weight (GPC silica gel permeation chromatography, polystyrene standard) of R resin of the present invention at 4000-100000, preferably 8000-50000, acid value Av<20mgKOH/g resin, preferably acid value Av<3mgKOH/g resin ,, Iodine value Iv=20-100gI2/100g resin, the best iodine value Iv=30-80I2/100g resin.

2. Synthesize the H resin component of the present invention.

First, the H resin component of the present invention will be described.

H resin main chain contains polydiene and aryl ether structure, relatively high molecular weight inert polyurethane acrylic resin, its role is to provide initial adhesion and good plate compatibility for the plate, and it has good resistance Ultraviolet destructive ability, the adhesive strength will not decrease with the increase of exposure.

The method for synthesizing the above-mentioned H resin is obtained through hydrogen transfer addition polymerization of diisocyanate, hydroxyl-terminated polydiene, and chain extender, and the end-group active-NCO adopts low-molecular-weight alcohol to block the end group.

The diisocyanates used in the synthesis of the H resin of the present invention can be selected from the diisocyanates listed in the synthesis of the R resin. In order to ensure that the H resin has a higher molecular weight and softening point, the diisocyanate is preferably a diisocyanate with a rigid structure, such as an aromatic diisocyanate or a six-membered alicyclic diisocyanate. Cyclohexylmethane diisocyanate (HMDI).

In order to have a good match between the adhesive and the elastomer and the substrate, the adhesive H resin component introduces a polydiene structural unit: HO-[(CH2-CR=CH-CH2)y(CH2- CHCN)x] n-OH (wherein, R is a hydrogen atom or a branched chain methyl group, when x=0, y=1, when x=1, y=1-10, n is a positive integer of 1-200), it and The flexibility and compatibility of the block polydiene elastomer and the substrate vinylidene chloride bottom layer are very good, and the thermal stability, oil resistance and tear resistance are all effective. Synthesizing the H resin of the present invention may be preferably polybutadiene diol (HTPB) or polybutadiene-acrylonitrile copolymer diol (HTBN) or a mixture of the two. The mass percentage content of the hydroxyl-terminated polydiene in the dihydroxy compound is 1-80%, and the optimum ratio is 10-50%.

In order to obtain a higher molecular weight, a low-molecular chain extender is used to synthesize the H resin of the present invention. The chain extender should be a dihydroxy compound with good chain extension performance, high temperature resistance, high hardness, and high elasticity. At least one chain extender contains- O-(aryl)-O-structure, preferably DMPA and 1-hydroxyethyl-4-oxoethyl hydroxyethyl phenylene ether (liquid HQEE) or 1-hydroxyethyl-3-oxoethyl hydroxy Ethyl phenylene ether (liquid HER) in combination.

The reaction temperature for synthesizing the H resin of the present invention is 40-100°C, preferably 60-80°C.

The catalyzer of synthesizing H resin of the present invention such as butyl lead, stannous octoate, dibutyltin dilaurate, trialkylphosphine, strong base, basic salt, cobalt, iron, tertiary amine etc. all can be used as matrix resin synthesis catalyst, preferably It is dibutyltin dilaurate, the dosage is 0.01-10% of the feed monomer, and the optimal dosage is 0.1-5%.

The solvent for synthesizing the H resin of the present invention is selected from solvents that do not contain active hydrogen (including water in the solvent), such as dried N,N-dimethylformamide, N,N-dimethylacetamide, etc., or their mixture. It is best to use polyurethane grade N,N-dimethylformamide or N,N-dimethylacetamide.

Synthesize H resin of the present invention, solvent adopts division to add, preferably adopt bulk polymerization or a small amount of solvent polymerization at initial stage of reaction, to reduce the influence of solvent, promote molecular chain growth, when molecular weight increases, add solvent in batches when stirring difficulty, like this A higher molecular weight can be obtained to ensure the initial adhesion of the adhesive.

Synthesize the solid content of H resin of the present invention at 10-100%, preferably at 30-70%.

The H resin of the present invention is synthesized, and the post-treatment can adopt the same treatment process as the R resin.

The weight-average molecular weight of the synthetic H resin of the present invention is 5,000-200,000, preferably 200,000-100,000, and the acid value Av=10-150mgKOH/g resin, and the best acid value Av=40-100mgKOH/g resin.

3. Preparation and coating of adhesive.

One of the characteristics and advantages of the UV-curable adhesive of the present invention is that the performance of the adhesive can be flexibly adjusted according to the needs of flexographic elastomers and properties of different substrates. Since the adhesive of the present invention does not contain monomers or viscous prepolymers, the shrinkage rate of the film is extremely small, and many properties of the adhesive such as initial adhesion, curing adhesion, flexibility, shrinkage, and durability High temperature performance can be adjusted by combining the ratio of R resin and H resin.

Contain photosensitizer in the bonding agent of the present invention, the photosensitizer that can add has benzophenone, michrone, 4-acetoxy group-4'-diethylamine benzophenone, benzoin ethyl ether, α-Hydroxyisopropylbenzophenone, α-Hydroxycyclohexylbenzophenone, 2-phenyl-2,2-dimethoxyacetophenone, 2-tert-butylanthraquinone, isopropylthioxanthene Quinone, (morpholinobenzoyl) 1-hexayl 1,1 (dimethylamino) propane, benzil, benzoin, etc., the added amount accounts for more than 0.2% of the total solids.

The solvent used for preparing the adhesive of the present invention can be alcohol solvents, ketone solvents, hydrocarbon solvents, amide solvents, ether solvents, lipid solvents, diol derivative solvents, etc., such as methanol, ethanol, acetone , butanone, cyclohexanone, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dichloromethane, benzene, toluene, ethyl acetate, ethylene glycol mono Methyl ether, ethylene glycol monoethyl ether, etc.

Adjuvants such as UV absorbers, anti-halation dyes, pigments, heat stabilizers, and oxygen scavenger can also be added to the adhesive.

The solid content of the adhesive described in the present invention accounts for more than 1% of the solvent content, and it is coated on the pretreated 80-150 μm polyethylene terephthalate (PET), polypropylene, triacetate and other flexible adhesives. On the substrate of the plate, the treatment method can be seen in the patent CN101144980. Coating methods can be dip coating, knife coating, extrusion coating and other coating methods. The coating amount of the adhesive is generally controlled at 1-5g/m2, the thickness is 0.1-5μm, and the total thickness of the bottom layer and the adhesive layer is 0.2-10μm. The substrate coated with the adhesive can be rolled up after drying, and stored at room temperature in the dark for 18 months, with almost no change in quality.

The adhesive of the present invention has a good bonding effect on the contact surface of high-oil-containing elastomers, and shows good adhesion to high-oil contact surfaces such as naphthenic oil, butyl oil, and silicone oil. The oil content of the elastomer layer is greater than 20%, the initial adhesion is not less than 10g/cm, and the exposure adhesion is greater than 1000/cm.

The following are synthesis and preparation examples of the present invention, which can illustrate the UV-curable adhesive of the present invention in more detail, but the present invention is not limited to the following examples.

Synthesis example 1 (synthesis of R resin: R-1﹟)

Add 90 ml of DMF (N,N-dimethylformamide) and 70.83 g (0.27 mol) of HMDI (dicyclohexylmethane) to a 500 ml four-necked flask with a reflux device and a drying tube. Diisocyanate), 11.77g (0.07mol) HDI (hexamethylene diisocyanate), stir well and add TEG (triethylene glycol) 12.01g (0.08mol), DMPA (2,2-bismethylol propionic acid) 34.87g (0.26mol), after the dissolution is complete, add 0.5g of dibutyltin dilaurate, raise the temperature to 60°C, keep warm for 2 hours, add DMF110ml, continue the reaction, add dibutyltin dilaurate after 5.5 hours 0.1 g, and 3.20 g (0.10 mol) of methanol as an end-blocking agent. Half an hour later, the reaction of the synthetic matrix resin RM was completed.

Add DMF160 ml, BTMA (benzyltrimethylammonium chloride) 5.60g, TPP (triphenylphosphine) 2.1g, ZJ-701 (nitroxyl piperidinol) 1.4 to the above matrix resin RM reaction solution in sequence g. CMA (3,4-epoxycyclohexyl acrylate) 56.48 g (0.31mol), stir well, react at 90°C for 2 hours, then raise the temperature to 120°C and continue the reaction for 2 hours, cool to room temperature, RM grafting reaction Finish.

Add DOX (dioxane) to the cooled reaction solution for dilution, drop the diluted reaction solution into 25L deionized water containing 90ml of glacial acetic acid to precipitate a solid resin, wash the solid resin and dry it under vacuum at 50°C to obtain a white solid R-1﹟, GPC weight average molecular weight Mw=17900, acid value Av<3mgKOH/g resin, iodine value Iv=37.32gI2/100g resin.

Synthesis example 2 (synthesis of R resin: R-2﹟)

Add 90 ml of DMF (N,N-dimethylformamide) and 70.83 g (0.27 mol) of HMDI (dicyclohexylmethane) to a 500 ml four-necked flask with a reflux device and a drying tube. Diisocyanate), 11.77g (0.07mol) HDI (hexamethylene diisocyanate), stir well and add TEG (triethylene glycol) 12.01g (0.08mol), DMPA (2,2-bismethylol propionic acid) 34.87g (0.26mol), after the dissolution is complete, add 0.5g of dibutyltin dilaurate, raise the temperature to 60°C, keep warm for 2 hours, add DMF110ml, continue the reaction, add dibutyltin dilaurate after 5.5 hours 0.1 g, and 3.20 g (0.10 mol) of methanol as an end-blocking agent. Half an hour later, the reaction of the synthetic matrix resin RM was completed.

Add DMF160 ml, BTMA (benzyltrimethylammonium chloride) 5.60g, TPP (triphenylphosphine) 2.1g, ZJ-701 (nitroxyl piperidinol) 1.4 to the above matrix resin RM reaction solution in sequence g. GMA (glycidyl methacrylate) 42.65g (0.30mol), stir evenly, react at 90°C for 2 hours, then raise the temperature to 120°C and continue the reaction for 2 hours, cool to room temperature, and the RM grafting reaction is completed.

Post-treatment process is the same as example 1, R-2﹟ resin GPC weight average molecular weight Mw=17500, acid value Av<3mgKOH/g resin, iodine value Iv=39.65gI2/100g resin.

Synthesis example 3 (synthesis of R resin: R-3﹟)

Add 81.33g (0.31mol) of HMDI (dicyclohexylmethane diisocyanate) and 6.73g (0.04mol) of HDI (hexamethylene diisocyanate) to a 500 ml four-necked flask with a reflux device and a drying tube. Add 10g (0.01mol) of PPG-1000 (polyoxypropylene glycol, molecular weight 1000±70, hydroxyl value 105-117)) which has been removed under reduced pressure and stir evenly, then add 0.5g of dibutyltin dilaurate and heat up to After 1.5 hours of bulk reaction at 80°C, cool down to 60°C, add 90 ml of DMF (N,N-dimethylformamide), DMPA (2,2-bismethylolpropane) dried over anhydrous sodium sulfate Acid) 45.60g (0.34mol), add DMF110ml after reaction for one hour, add 0.1g of dibutyltin dilaurate and end-blocker methanol 3.20g (0.10mol) after continuing reaction for 4 hours, synthesize matrix resin after half an hour The RM reaction is complete.

Add DMF160 ml, BTMA (benzyltrimethylammonium chloride) 7.11g, TPP (triphenylphosphine) 2.1g, 4.28 (nitrogen free radical piperidinol) 1.4g, CMA (3,4-epoxycyclohexyl acrylate) 71.24g (0.39mol), stirred evenly, reacted at 90°C for 2 hours, then raised the temperature to 120°C to continue the reaction for 2 hours, cooled to room temperature, and the RM grafting reaction was completed.

Post-treatment process is the same as example 1, R-3﹟ resin GPC weight average molecular weight Mw=21400, acid value Av<3mgKOH/g resin, iodine value Iv=41.20gI2/100g resin.

Synthesis example 4 (synthesis of R resin: R-4﹟)

Add 91.82g (0.35mol) HMDI (dicyclohexylmethane diisocyanate) and PPG-1000 (polyoxypropylene glycol, molecular weight 1000± 70, hydroxyl value 105-117)) 10g (0.01mol) after stirring evenly, add 0.5g of dibutyltin dilaurate, heat up to 80°C, react in bulk for 1.5 hours, add 90 ml and dry over anhydrous sodium sulfate DMF (N,N-dimethylformamide), DMPA (2,2-bismethylolpropionic acid) 45.60g (0.34mol), add DMF110ml after reaction for one hour, continue reaction for 4 hours, then cool down to At 60°C, add 0.1 g of dibutyltin dilaurate and 3.20 g (0.10 mol) of methanol as an end-blocking agent. After half an hour, the reaction of the synthetic matrix resin RM is completed.

Add DMF160 ml, BTMA (benzyltrimethylammonium chloride) 7.11g, TPP (triphenylphosphine) 2.1g, 4.28 (nitrogen free radical piperidinol) 1.4g, GMA (glycidyl methacrylate) 55.58g (0.391mol), stirred evenly, reacted at 90°C for 2 hours, then raised the temperature to 120°C to continue the reaction for 2 hours, cooled to room temperature, and the RM grafting reaction was completed.

Post-treatment process is the same as example 1, R-4﹟ resin GPC weight average molecular weight Mw=21400, acid value Av<3mgKOH/g resin, iodine value Iv=44.08gI2/100g resin.

Synthesis example 5 (Synthesis of H resin: H-1﹟)

Add 131.18g (0.50mol) HMDI (dicyclohexylmethane diisocyanate), 50g (about 0.05mol) HDPB (polybutadiene diol, Mn: 2000, Hydroxyl value: about 1.00m mol/g), 0.5g of dibutyltin dilaurate, stir well and then raise the temperature to 80°C, react in bulk for 1 hour, add 110ml of DMAC (N,N-dimethylacetamide), DMPA (2,2-bismethylolpropionic acid) 53.65g (0.40mol), HQEE-L (4-hydroxyethyloxyethyl-1-hydroxyethylphenylene ether) 12.11g (0.05mol), continue the reaction , add 50ml of DMAC (N,N-dimethylacetamide) every 0.5 hours, 5 times a total of 250ml, after a total reaction time of 5.5 hours, add 0.1g of dibutyltin dilaurate, 3.20g of end-blocking agent methanol (0.10mol ), after half an hour, the synthetic H resin reaction was completed.

The post-treatment process is the same as Example 1, H-1﹟ resin GPC weight average molecular weight Mw=47840, acid value Av=90.87mgKOH/g resin.

Synthesis example 6 (Synthesis of H resin: H-2﹟)

Add 104.94g (0.40mol) HMDI (dicyclohexylmethane diisocyanate), 16.82g (0.10mol) HDI (hexamethylene diisocyanate), 40g (approx. 0.04mol) HDPB (polybutadiene diol, Mn: 2000, hydroxyl value: about 1.00m mol/g), 0.5g of dibutyltin dilaurate, stir well and heat up to the internal temperature of 80°C, after 1 hour of bulk reaction , add 110ml of DMAC (N,N-dimethylacetamide), DMPA (2,2-bismethylolpropionic acid) 40.24g (0.30mol), HER-L (1-hydroxyethyl-3-oxyethyl Hydroxyethylphenylene ether) 38.76g (0.16mol), continue the reaction, add 50ml of DMAC (N,N-dimethylacetamide) every 0.5 hours, 5 times a total of 250ml, add dilaurel after the total reaction time of 5.5 hours 0.1 g of dibutyltin acid, 3.20 g (0.10 mol) of methanol as an end-blocking agent, and half an hour later, the synthesis of H resin was completed.

The post-treatment process is the same as Example 1, H-2﹟ resin GPC weight average molecular weight Mw=45360, acid value Av=69.90mgKOH/g resin.

Synthesis example 7 (Synthesis of H resin: H-3﹟)

Add 131.18g (0.50mol) HMDI (dicyclohexylmethane diisocyanate), 50g (about 0.025mol) HTBN (hydroxyl-terminated polybutadiene acrylonitrile, Mn: 2000, hydroxyl value: about 0.50m mol/g), 0.5g of dibutyltin dilaurate, stir evenly and then raise the temperature to 80°C, after bulk reaction for 1 hour, add 110ml of DMAC (N,N-dimethylacetamide) , DMPA (2,2-bismethylolpropionic acid) 53.65g (0.40mol), HQEE-L (4-hydroxyethyloxyethyl-1-hydroxyethylphenylene ether) 18.17g (0.075mol), Continue the reaction, adding 50ml of DMAC (N,N-dimethylacetamide) every 0.5 hours, 5 times for a total of 250ml, after a total reaction time of 5.5 hours, add 0.1g of dibutyltin dilaurate and 3.20g of methanol as an end-blocking agent ( 0.10mol), half an hour later, the synthetic H resin reaction was completed.

Add DOX (dioxane) to the cooled reaction solution for dilution, drop the diluted reaction solution into 25L deionized water containing 90ml of glacial acetic acid to precipitate a solid resin, wash the solid resin and dry it under vacuum at 50°C to obtain a white solid H-3﹟ resin GPC weight average molecular weight Mw=51790, acid value Av=88.70mgKOH/g resin.

Synthesis example 8 (Synthesis of H resin: H-4﹟)

Add 104.94g (0.40mol) HMDI (dicyclohexylmethane diisocyanate), 16.82g (0.10mol) HDI (hexamethylene diisocyanate), 40g (approx. 0.02mol) HTBN (hydroxyl-terminated polybutadiene acrylonitrile, Mn: 2000, hydroxyl value: about 0.50m mol/g), 0.5g of dibutyltin dilaurate, stir evenly and heat up to internal temperature 80°C, bulk reaction 1 After one hour, add 110ml of DMAC (N,N-dimethylacetamide), DMPA (2,2-bismethylol propionic acid) 40.24g (0.30mol), HER-L (1-hydroxyethyl-3-oxygen Ethyl hydroxyethyl phenylene ether) 43.61g (0.16mol), continue the reaction, add 50ml of DMAC (N,N-dimethylacetamide) every 0.5 hours, 5 times a total of 250ml, add after the total reaction time of 5.5 hours 0.1 g of dibutyltin dilaurate and 3.20 g (0.10 mol) of methanol as an end-blocking agent. After half an hour, the synthesis of H resin was completed.

Post-treatment process is the same as example 1, H-4﹟ resin GPC weight average molecular weight Mw=50760, acid value Av=68.85mgKOH/g resin.

Select the R-1﹟ resin and H-1﹟ resin synthesized above to prepare the adhesive N-1﹟ of the example.

Adhesive N-1﹟: Ethylene glycol monomethyl ether 100g, toluene 50g, R-1﹟10g, H-1﹟10g, dissolve at room temperature. Then add 0.5 g of initiator (184), 0.2 g of 2,6-di-tert-butyl-p-cresol, and 0.1 g of Fc-4430# (manufactured by 3M Company), and stir in a closed container for 1 hour under a yellow safety light. Get adhesive 1﹟.

Prepare adhesives N-2﹟ to N-15﹟ according to the ratio in Table 1 below and the preparation process of adhesive N-1﹟ (the ratio of solvent, initiator and auxiliary agent is exactly the same).

The above-mentioned adhesive was coated on the base film at a vehicle speed of 25 m/min, and dried at 50° C. for 15 minutes, with a coating amount of 1 g/square meter and a thickness of 1 μm. A flexible photosensitive resin plate is obtained by laminating the adhesive-coated support with a flexographic photosensitive resin layer with a thickness of 3.94mm or 1.70mm produced by DuPont or Lucky Group at 120°C and a pressure of 0.15-14MPa. The 365nm ultraviolet light intensity of Jiangsu Taiyi Group's flexible plate-making machine is 7.3 mW/cm2, and the peeling force is measured by BLD-200S electronic peeling tester produced by Jinan Languang Electromechanical Technology Co., Ltd. Among them, F0 is the unexposed adhesive force, F1 is the adhesive force of UV back exposure for 1 minute, F20 is the adhesive force of UV positive exposure for 20 minutes, and the unit of adhesive force is g/cm.

Table 1

Note: In the comparative example, PU-Ⅱ is polyurethane resin, PA-1 is active polyacrylic resin, PT-B is solvent-based hot-melt resin, all produced by Lucky Film Company, and MPODA is active monomer 2-methyl-1 , 3-propylene glycol diacrylate.

It can be seen from the above table:

1. The adhesives of the embodiments N-1﹟ to N-6﹟ of the present invention do not contain pre-polymerized monomers, the film is not sticky to the hand, can be pre-coated, and has good stability (the shelf life of the pre-coated film is 18 months); The adhesive is resistant to high temperature of 120°C, and the initial adhesion to high-oil elastomers is greater than 10g/cm2, which is required for the production of flexo plates. After 1 minute of ultraviolet exposure, it can produce strong adhesion, and the adhesion is much higher than the standard of 1000g/cm2; After 20 minutes of UV exposure, the film is flexible, with little shrinkage, no deformation of the plate, and the adhesive force meets the requirements of the plate; in addition, it can be seen from the examples of N-5﹟-N-12﹟ that by adjusting the ratio of R resin and H resin , It can reduce the damage of internal stress caused by ultraviolet overexposure, and the adhesion force drops little after 20 minutes of ultraviolet exposure.

2. In the comparative example, N-13﹟ and N-14﹟ adhesives contain pre-polymerized monomers, the film is sticky, cannot be pre-coated, is not resistant to high temperature, has poor stability, and the film shrinks after ultraviolet exposure, and the internal stress is large. The initial tack of the high-oil interface and the UV-cured adhesive force are very small, which cannot meet the production requirements of flexo plates; the N-15﹟ hot-melt adhesive film is brittle, and the adhesive force cannot meet the standard, so it cannot be used. the

Claims (6)

1. ultraviolet light polymerization caking agent, mainly by resin body, solvent, ultraviolet initiator and auxiliary agent are formed, it is characterized in that: its resin body is formed by containing the inertia polyurethane acrylic resin H that polyether structure active polyurethane acrylic resin R and main chain have polydiene and aryl oxide structure, the weight ratio of resin R and resin H is 1:10-10:1 in the caking agent, the resin matrix of described resin R obtains by vulcabond and dihydroxy compound polyreaction, described dihydroxy compound comprises polyether glycol and carboxylic dihydroxy compound, and end group activity-NCO adopts the low mass molecule alcohol sealing; Optical active group is to obtain by the open loop of side chain carboxyl, condensation reaction grafted ethene based compound, and the weight-average molecular weight of resin R is 4000-100000, acid number Av＜20mgKOH/g resin, iodine number Iv=20-100gI ₂/ 100g resin;

Described grafted ethene based compound is 3,4-epoxycyclohexyl acrylate or glycidyl methacrylate or the combination of the two, and the vinyl graft copolymer compound is 0.8:1-1.5:1 with containing carboxyl dihydroxy compound mol ratio;

Described resin H obtains by vulcabond and terminal hydroxy group polydiene compound and at least a aryl oxide chainextender polyreaction, end group activity-NCO adopts the low mass molecule alcohol sealing, the resin weight-average molecular weight is 5000-200000, acid number Av=10-150mgKOH/g resin.

2. ultraviolet light polymerization caking agent according to claim 1 is characterized in that: described vulcabond is at least a in aliphatic diisocyanate, the alicyclic diisocyanate.

3. ultraviolet light polymerization caking agent according to claim 1, it is characterized in that: described polyether glycol, its backbone structure contains HO-[CH at least ₂-CH (R)-O-] _n-OH segment, in the formula-R represents hydrogen atom or branched chain methyl, and n is the 3-200 integer, and the mass percentage content of polyether glycol in dihydroxy compound is 1-50%.

4. ultraviolet light polymerization caking agent according to claim 1, it is characterized in that: the described carboxyl dihydroxy compound that contains is 2, the two hydroxymethyl propionic acids of 2-or 3,5-resorcylic acid, containing the mass percentage content of carboxyl dihydroxy compound in dihydroxy compound is 50-99%.

5. ultraviolet light polymerization caking agent according to claim 1, it is characterized in that: described terminal hydroxy group diolefin contains repeating segment HO-[(CH ₂-CR=CH-CH ₂) _y(CH ₂-CHCN) _x] _n-OH, wherein, R is hydrogen atom or branched chain methyl, x=0, y=1, n are the 1-200 positive integer.

6. ultraviolet light polymerization caking agent according to claim 1, it is characterized in that: described terminal hydroxy group diolefin contains repeating segment HO-[(CH ₂-CR=CH-CH ₂) _y(CH ₂-CHCN) _x] _n-OH, wherein, R is hydrogen atom or branched chain methyl, x=1, y=1-10, n are the 1-200 positive integer.