Polyacrylate containing photocurable olefinic groups in the side chain and UV viscosity-reducing adhesive composition

Abstract

The present application specifically discloses a polyacrylate containing photocurable alkenyl groups in the side chain and a UV viscosity-reducing adhesive composition. The polyacrylate is polymerized by thermal reaction with a polyurethane monomer containing different active alkenyl groups, a hydroxyl- and alkenyl-terminated acrylic acid ester copolymer, a flexible monomer and a rigid monomer. The UV viscosity-reducing adhesive composition mixed with such a polyacrylate containing photocurable alkenyl groups in the side chain can fully infiltrate the epoxy molding material of the electronic components, and has a high adhesion to the epoxy molding material; at the same time, the UV viscosity-reducing adhesive composition does not need to use low molecular weight UV monomers and UV prepolymers. After low-energy UVLED irradiation and curing, the peel strength of the UV viscosity-reducing adhesive composition is greatly reduced, and the residual adhesive phenomenon is avoided.

Description

Technical Field

[0001] The present application relates to the technical field of adhesives, and more specifically, to a polyacrylate containing photocurable olefin groups in the side chains and a UV viscosity-reducing adhesive composition. Background Art

[0002] With the development of the semiconductor industry, UV adhesive has been widely used in the wafer manufacturing process. Its main function is to have sufficient adhesion to fix the wafer during the manufacturing process for cutting, thinning and other processing operations. After processing, the UV adhesive peeling force is greatly reduced through UV irradiation, and the adhesive loses its viscosity, making it easier to pick up the device.

[0003] At present, UV viscosity-reducing adhesives generally use acrylate resins as the main component, and physically mix polyacrylates, high-functionality UV resins, UV monomers, and photoinitiators, and use a large amount of solvents to improve the compatibility of different types of resins. Therefore, the existing UV viscosity-reducing adhesives are prone to uneven peeling force and low cohesive force of the adhesive layer before UV LED irradiation; at the same time, the existing UV viscosity-reducing adhesives have a small drop in peeling force after UV LED irradiation, and residual adhesive is prone to occur. For example, Lee et al. mixed acrylate copolymers, hexafunctional acrylic monomers, and photoinitiators to prepare acrylate UV viscosity-reducing adhesives. Due to the current chip manufacturing process, epoxy resin is usually used as a plastic encapsulation material to encapsulate the chip substrate. However, spherical silicon, palm wax, and other substances are added to the epoxy plastic encapsulation material, resulting in the acrylate UV viscosity-reducing adhesive not being firmly bonded to the epoxy plastic encapsulation material, which is manifested as the low peeling force of the acrylate UV viscosity-reducing adhesive on the epoxy plastic encapsulation material, and bubbles are easily generated during the bonding process, resulting in easy displacement and flying materials during the cutting process. During the rinsing process, water can easily enter the components and cause damage to them. In addition, the peeling force of the acrylic UV viscosity-reducing adhesive after UV light curing is 7.8N / 25mm, and residual adhesive remains after peeling.

[0004] Based on the above situation, the industry is in urgent need of a UV viscosity-reducing adhesive that has high peeling force before UV curing and significantly reduced peeling force after UV curing. Summary of the invention

[0005] The present application provides a polyacrylate containing a photocurable olefin group in the side chain, a UV viscosity-reducing adhesive composition and a preparation method thereof, so that the prepared UV viscosity-reducing adhesive can have high peeling force before UV curing and firmly adhere to the epoxy packaging material; and the peeling force is significantly reduced after UV curing, and there is no residual adhesive on the epoxy packaging material.

[0006] In a first aspect, the present application provides a polyacrylate having a photocurable olefinic group in a side chain, using the following technical solution:

[0007] A polyacrylate containing a photocurable olefin group in the side chain is prepared by reacting the following raw materials in parts by weight:

[0008] 2-5 parts of polyurethane monomers containing different active olefin groups, 0.8-3 parts of hydroxyl and olefin-terminated acrylate copolymer monomers, 80-95 parts of flexible monomers, 8-15 parts of rigid monomers, 0.1-1 parts of thermal initiators and 200-290 parts of solvents.

[0009] Furthermore, the polyurethane monomer containing different active alkenyl groups is prepared by reacting isocyanate, acrylate containing alkenyl and hydroxyl groups, a catalyst and an inhibitor.

[0010] The isocyanate satisfies at least one of the following characteristics:

[0011] diisocyanates include toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, xylylene diisocyanate, and tetramethyl-m-xylylene diisocyanate;

[0012] Polyisocyanates include triphenylmethane triisocyanate, toluene diisocyanate trimer and polyphenyl polymethylene polyisocyanate.

[0013] The acrylate containing alkenyl and hydroxyl groups satisfies at least one of the following characteristics:

[0014] Pentaerythritol triacrylate, hydroxyethyl acrylate and 2-hydroxypropyl acrylate.

[0015] The catalyst satisfies at least one of the following characteristics:

[0016] Metal catalysts include dibutyltin dilaurate, stannous isooctanoate, zinc isooctanoate, and bismuth isooctanoate;

[0017] Amine catalysts include diethylenediamine and triethylenediamine.

[0018] The inhibitor satisfies at least one of the following characteristics:

[0019] Polyphenol inhibitors include hydroquinone, p-hydroxyanisole, 2,6-di-tert-butyl-p-cresol, p-tert-butylcatechol, 4,4'-diaminobiphenyl and bisphenol A;

[0020] Quinone inhibitors include chloranil and 1,4-naphthoquinone.

[0021] Furthermore, the specific steps of preparing the polyurethane monomer containing different active olefin groups include: feeding the raw materials at 30-50° C. by starvation feeding method, heating to 50-65° C. and keeping the temperature for reaction for 2-4 hours.

[0022] Furthermore, the hydroxyl- and olefin-terminated acrylate comonomer is prepared by copolymerization of primary hydroxycaprolactone oligomer and acrylic acid.

[0023] The selection of caprolactone and acrylic acid comonomers includes, but is not limited to, PLACCEL FA1DDM, PLACCEL FA3, PLACCEL FM5, PLACCEL FA1, PLACCEL FA2D, PLACCEL FA5, and PLACCEL FA10L*1.

[0024] Furthermore, the flexible monomer satisfies at least one of the following characteristics:

[0025] Long-chain monofunctional acrylates include butyl acrylate, isooctyl acrylate, 2-propylheptyl acrylate, and isobutyl acrylate;

[0026] Non-aromatic carbocyclic monofunctional acrylates include cyclohexyl acrylate.

[0027] Furthermore, the rigid monomer satisfies at least one of the following characteristics:

[0028] Methyl acrylate, phenyl methacrylate, methacryloyloxyethyl acrylate and phenyl acrylate.

[0029] Furthermore, the thermal initiator satisfies at least one of the following characteristics:

[0030] Azo initiators include azobisisobutyronitrile and azobisisoheptanenitrile;

[0031] Organic peroxy initiators include dibenzoyl peroxide, diethylhexyl peroxydicarbonate, dibenzoyl peroxide and t-butyl perbenzoate.

[0032] Furthermore, the solvent satisfies at least one of the following characteristics: ethyl acetate, butyl acetate, acetone, methyl ethyl ketone and toluene.

[0033] In a second aspect, the present application provides a UV viscosity-reducing adhesive composition, which adopts the following technical solution:

[0034] A UV viscosity-reducing adhesive composition comprises the following components in parts by weight:

[0035] The aforementioned polyacrylate containing photocurable alkenyl groups in the side chain comprises 80 to 100 parts, a curing agent comprises 0.05 to 0.5 parts, a photoinitiator comprises 2.5 to 5 parts and a diluent comprises 80 to 100 parts.

[0036] Furthermore, the UV viscosity-reducing adhesive composition also includes a leveling agent, and the weight portion of the leveling agent is 0.01 to 0.05 parts.

[0037] The leveling agent meets at least one of the following characteristics: the organic silicone leveling agent includes HY-5030, HY-5057, BYK333 and BYK361N.

[0038] Furthermore, the curing agent satisfies at least one of the following characteristics:

[0039] Diisocyanate curing agents include 2,6-toluene diisocyanate, 1,3,3-trimethyl-5-isocyanato-1-isocyanatomethylcyclohexane, 4,4-dicyclohexylmethane diisocyanate, 1,6-diisocyanatohexane, trimethylhexane diisocyanate and xylylene diisocyanate;

[0040] Polyisocyanate curing agents include biuret-type polyisocyanates, trimer-type polyisocyanates, and adduct-type polyisocyanates;

[0041] Biuret type polyisocyanates include grades 22A-75PX and 24A-100;

[0042] Trimer polyisocyanates include grades TPA-100, TKA-100, TFD-90SB, MHG-80B, TMA-100, TLA-100, TUL-100, TSE-100 and Desmodur N3390;

[0043] Adduct-type polyisocyanates include grades E402-80B, E405-80T and Desmodur L75.

[0044] Furthermore, the photoinitiator satisfies at least one of the following characteristics:

[0045] The cleavage-type free radical photoinitiator includes benzoin and its derivatives, benzil derivatives, dialkoxyacetophenones, α-hydroxyalkyl phenones, α-aminoalkyl phenones, acylphosphine oxides; for example, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 1-hydroxycyclohexyl phenyl ketone and phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide;

[0046] The hydrogen abstraction type photoinitiator includes benzophenone or heterocyclic aromatic ketone compounds; for example, benzophenone, 4-methylbenzophenone and 2,4,6-trimethylbenzophenone.

[0047] In summary, the technical solution of this application has at least the following advantages:

[0048] First, the present application uses polyurethane monomers containing different active alkenyl groups and acrylate copolymers terminated with hydroxyl groups and alkenyl groups as reaction raw materials. One alkenyl group in the polyurethane monomers containing different active alkenyl groups reacts, and the other alkenyl group is retained. The primary hydroxyl groups of the acrylate copolymers terminated with hydroxyl groups and alkenyl groups are far away from the ends of the main chain skeleton, and are easy to react with curing agents such as amino resins and polyurethane resins. At the same time, the bridging reaction can proceed smoothly to form an elastic and tough adhesive film.

[0049] During the thermal polymerization process, the alkenyl groups of the side chains of polyacrylates are retained due to the steric effect. Therefore, it is not necessary to use small molecule UV monomers in the UV viscosity reducer using this polyacrylate, thereby effectively avoiding the damage of the residual small molecule UV monomers to electronic components.

[0050] At the same time, the hydroxyl groups on the polyacrylate react with the isocyanate groups in the curing agent to form a dense network cross-linked structure. When irradiated by UVLED, the olefin groups on the polyacrylate undergo free radical polymerization to form a network cross-linked structure, thereby increasing the glass transition temperature (Tg) of the adhesive layer, shrinking the adhesive layer, increasing stress and losing viscosity, achieving a viscosity reduction effect. Under the synergistic effect of the two, an integrated, mutually entangled cross-linked network structure is formed, thereby avoiding residual glue.

[0051] Secondly, the caprolactone side chains and flexible monomers on the polyacrylate improve the wettability of the UV viscosity-reducing adhesive, thereby helping to improve the adhesion and wettability of the UV viscosity-reducing adhesive before UV curing.

[0052] Second, in the present application, a leveling agent is also added to the UV viscosity-reducing adhesive. The surface activity of the leveling agent can help the UV viscosity-reducing adhesive to discharge bubbles in time during lamination, further enhancing the adhesion of the UV viscosity-reducing adhesive before UV curing. DETAILED DESCRIPTION

[0053] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the technical solutions of the present application are further described below in conjunction with embodiments.

[0054] Preparation examples of polyurethane monomers containing different active olefin groups

[0055] Preparation Example 1

[0056] The raw materials of polyurethane monomers containing different active olefin groups include, by weight:

[0057] 100 parts of hexamethylene diisocyanate;

[0058] Pentaerythritol triacrylate 237 parts;

[0059] 76 parts of hydroxyethyl acrylate;

[0060] 0.12 parts of dibutyltin dilaurate;

[0061] 0.2 parts of p-hydroxyanisole;

[0062] Prepared according to the following steps:

[0063] Add hexamethylene diisocyanate and p-hydroxyanisole into a dry container with stirring and a thermometer, slowly raise the temperature to 30°C, and drop pentaerythritol triacrylate. Since this reaction is an exothermic reaction, control the drop rate to keep the reaction temperature at 55-65°C. After the dropwise addition is completed, keep the temperature at 65°C for 2 hours, and the NCO reaches the theoretical value of 7.5%. Continue to drop hydroxyethyl acrylate, maintain the reaction temperature at 65-70°C for 3 hours, until the NCO is zero. Put it into a dry container, seal it, protect it from light, and set it aside.

[0064] Preparation Example 2

[0065] The polyurethane monomers containing different active olefin groups are different from those in Preparation Example 1 in terms of the selection of raw materials, as follows:

[0066] 100 parts of toluene diisocyanate trimer;

[0067] Pentaerythritol triacrylate 237 parts;

[0068] 2-Hydroxypropyl 2-acrylate 76 parts;

[0069] 0.12 parts of stannous isooctanoate;

[0070] 0.2 parts of p-tert-butylcatechol;

[0071] Prepared according to the following steps:

[0072] Add toluene diisocyanate trimer and tert-butyl catechol into a dry container with stirring and thermometer, slowly raise the temperature to 50℃, and drop pentaerythritol triacrylate. Since this reaction is an exothermic reaction, control the drop rate to keep the reaction temperature at 50-60℃. After the dropwise addition is completed, keep the temperature at 60℃ for 4h, and test that NCO reaches the theoretical value of 7.5%. Continue to drop hydroxyethyl acrylate, maintain the reaction temperature at 65-70℃ for 3h, until NCO is zero. Put it into a dry container, seal it, avoid light, and set aside.

[0073] Example

[0074] Example 1

[0075] A polyacrylate having a photocurable olefinic group in the side chain, wherein the raw materials thereof include, by weight:

[0076] 2 parts of polyurethane monomers containing different active olefin groups (prepared in Preparation Example 1);

[0077] 2 parts of hydroxyl and olefin-terminated acrylate comonomer PLACCEL FA1DDM;

[0078] 85 parts of isooctyl acrylate;

[0079] Methyl acrylate 9 parts;

[0080] 4 parts of hydroxyethyl acrylate;

[0081] 0.5 parts of azobisisobutyronitrile;

[0082] 270 parts of ethyl acetate;

[0083] Follow these steps to make it:

[0084] Add 1 / 3 parts by weight of isooctyl acrylate, PLACCEL FA1DDM, methyl acrylate and hydroxyethyl acrylate into a container equipped with a stirring paddle, a spherical condenser and a constant pressure dropping funnel, add 1 / 3 parts by weight of azobisisobutyronitrile dropwise, slowly raise the temperature to 80±2°C, and after the temperature stabilizes, continue to add the remaining monomers and initiator to carry out polymerization reaction, finally add polyurethane monomers containing different active olefin groups, the remaining initiator and solvent to obtain polyacrylates containing photocurable olefin groups in the side chains, which are set aside.

[0085] Example 2

[0086] A polyacrylate containing photocurable alkenyl groups in the side chain, which is different from Example 1 in that the amount of polyurethane monomers containing different active alkenyl groups (prepared in Preparation Example 1) added is 3 parts.

[0087] Example 3

[0088] A polyacrylate containing photocurable alkenyl groups in the side chain, which is different from Example 1 in that the amount of polyurethane monomers containing different active alkenyl groups (prepared in Preparation Example 1) added is 4 parts.

[0089] Example 4

[0090] A polyacrylate containing photocurable alkenyl groups in the side chain, which is different from Example 1 in that the amount of polyurethane monomers containing different active alkenyl groups (prepared in Preparation Example 1) added is 5 parts.

[0091] Example 5

[0092] A polyacrylate containing photocurable alkenyl groups in the side chain, which is different from Example 3 in that the amount of hydroxyl- and alkenyl-terminated acrylic ester comonomer PLACCEL FA1DDM added is 3 parts.

[0093] Example 6

[0094] A polyacrylate containing photocurable alkenyl groups in the side chain, which is different from Example 3 in that the amount of the hydroxyl- and alkenyl-terminated acrylic ester comonomer PLACCEL FA1DDM added is 0.8 parts.

[0095] Example 7

[0096] A polyacrylate having a photocurable olefinic group in the side chain, which is different from Example 1 in that the raw material composition is different, as follows:

[0097] 2 parts of polyurethane monomers containing different active olefin groups (prepared by Preparation Example 1), 2 parts of hydroxyl and olefin-terminated acrylate copolymer monomers, 80 parts of cyclohexyl acrylate, 8 parts of methyl acrylate, 2 parts of hydroxyethyl acrylate, 0.1 parts of thermal initiator dibenzoyl peroxide and 200 parts of ethyl acetate.

[0098] Example 8

[0099] A polyacrylate having a photocurable olefinic group in the side chain, which is different from Example 1 in that the raw material composition is different, as follows:

[0100] 2 parts of polyurethane monomers containing different active olefin groups (prepared by Preparation Example 1), 2 parts of hydroxyl and olefin-terminated acrylate copolymer monomers, 95 parts of cyclohexyl acrylate, 15 parts of methyl acrylate, 6 parts of hydroxyethyl acrylate, 1 part of thermal initiator dibenzoyl peroxide and 290 parts of ethyl acetate.

[0101] Comparative Example

[0102] Comparative Example 1

[0103] A polyacrylate, which differs from Example 1 in that isocyanate ethyl acrylate is used in equal parts by weight to replace the polyurethane monomers containing different active olefin groups.

[0104] Application Examples

[0105] Application Example 1

[0106] A UV viscosity-reducing adhesive composition, wherein the raw materials thereof include, by weight:

[0107] 100 parts of polyacrylate containing photocurable alkenyl groups in the side chain (prepared in Preparation Example 1);

[0108] Curing agent polyisocyanate Desmodur L75 0.1 part;

[0109] 2,4,6-trimethylbenzoyl-diphenylphosphine oxide 5 parts;

[0110] BYK333 0.02 parts;

[0111] 100 parts of ethyl acetate;

[0112] Follow these steps to make it:

[0113] Add polyacrylate containing photocurable alkenyl groups in the side chain into a container, add ethyl acetate to dilute, then add 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and leveling agent BYK333, stir for 0.5 h, then add polyisocyanate Desmodur L75 and stir for 0.5 h, discharge, and obtain a UV viscosity-reducing adhesive composition.

[0114] Application Example 2-8

[0115] A UV viscosity-reducing adhesive composition, which is different from Example 1 in that the polyacrylate containing a photocurable olefin group in the side chain has a different source, and the specific source is as follows:

[0116] The polyacrylate containing a photocurable olefinic group in the side chain of Application Example 2 is derived from Example 2;

[0117] The polyacrylate containing a photocurable alkenyl group in the side chain in Application Example 3 is derived from Example 3;

[0118] The polyacrylate containing a photocurable alkenyl group in the side chain of Application Example 4 is derived from Example 4;

[0119] The polyacrylate containing a photocurable alkenyl group in the side chain of Application Example 5 is derived from Example 5;

[0120] The polyacrylate containing a photocurable alkenyl group in the side chain of Application Example 6 is derived from Example 6;

[0121] The polyacrylate containing a photocurable alkenyl group in the side chain of Application Example 7 is derived from Example 7;

[0122] The polyacrylate containing a photocurable olefinic group in the side chain in Application Example 8 is derived from Example 8.

[0123] Application Example 9

[0124] A UV viscosity-reducing adhesive composition, wherein the raw materials thereof include, by weight:

[0125] 90 parts of polyacrylate containing photocurable alkenyl groups in the side chain (prepared in Preparation Example 1);

[0126] Curing agent polyisocyanate Desmodur L75 0.5 parts;

[0127] 4 parts of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide;

[0128] BYK333 0.05 parts;

[0129] 90 parts of ethyl acetate.

[0130] Application Example 10

[0131] A UV viscosity-reducing adhesive composition, wherein the raw materials thereof include, by weight:

[0132] 80 parts of polyacrylate containing photocurable alkenyl groups in the side chain (prepared in Preparation Example 1);

[0133] Curing agent polyisocyanate Desmodur L75 0.05 parts;

[0134] 2.5 parts of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide;

[0135] BYK333 0.01 part;

[0136] 80 parts of ethyl acetate.

[0137] Application Example 11

[0138] A UV viscosity-reducing adhesive composition, which differs from Application Example 3 in that an equal amount of weight of leveling agent MONENG-1153 is used to replace the silicone leveling agent BYK333.

[0139] Application Example 12

[0140] A UV viscosity-reducing adhesive composition, which differs from Application Example 3 in that ethyl acetate is used in equal parts by weight to replace the leveling agent BYK333.

[0141] Application comparison

[0142] Application Comparative Example 1

[0143] A UV adhesive composition, which differs from Example 1 in that the type of polyacrylate is different, and the polyacrylate (brand: Changxing Material 7718T) used in Comparative Example 1 is used to replace the polyacrylate containing a photocurable olefin group in the side chain prepared in Preparation Example 1.

[0144] Application Comparative Example 2

[0145] A UV viscosity-reducing adhesive composition, which is different from Example 1 in that the type of polyacrylate is different and a UV monomer containing an olefin group is added, specifically:

[0146] 100 parts of polyacrylate (brand: Changxing Materials 7718T);

[0147] 8 parts of UV monomer containing alkenyl (dipentaerythritol hexaacrylate);

[0148] Curing agent polyisocyanate Desmodur L75 0.1 part;

[0149] 2,4,6-trimethylbenzoyl-diphenylphosphine oxide 5 parts;

[0150] BYK333 0.02 parts;

[0151] 100 parts of ethyl acetate.

[0152] Application Comparative Example 3

[0153] A UV viscosity-reducing adhesive composition is different from Example 1 in that the type of polyacrylate is different, and the polyacrylate prepared in Comparative Example 1 is used in Comparative Example 3 instead of the polyacrylate containing photocurable olefin groups in the side chain prepared in Example 1.

[0154] Performance Testing

[0155] 1. 180° peel strength before irradiation (N / cm): The UV viscosity-reducing adhesive compositions obtained in Application Example 1 and Comparative Examples 1-3 were cut into 5 cm × 1 cm sizes, attached to a stainless steel plate (SUS) and an epoxy molding material plate, and pressed 6 times with a 2 kg roller. The 180° peel strength was recorded at room temperature;

[0156] 2. 180° peel strength after irradiation (N / cm): The UV de-viscosity adhesive composition pasted on the stainless steel plate (SUS) and the epoxy plastic sealing material plate is irradiated at 600mJ / cm 2 Under the irradiation dose, after irradiation curing, at room temperature, the 180° peel strength was recorded;

[0157] 3. State of the sample surface after peeling: record whether there is any glue-like substance remaining on the surface of the SUS steel plate and the epoxy plastic sealing material after the UV viscosity-reducing adhesive composition is peeled off.

[0158] Table 2. Properties of coatings obtained from application examples 1-12 and comparative examples 1-3 of this application

[0159]

[0160] According to the test data, it can be seen that in Application Example 1, polyacrylate commonly sold on the market is used. There is no photocurable olefin group on the side chain segment of the common polyacrylate, and in the absence of UV monomer and UV prepolymer, Application Example 1 cannot be cured after low-dose UV irradiation, and it has almost no glue reduction ability, and the peel strength is as high as 500g / cm3 or more. Therefore, there are serious colloid residues on the SUS steel plate and the epoxy molding material.

[0161] Application Example 2 adds the alkenyl-containing UV monomer dipentaerythritol hexaacrylate on the basis of Application Example 1. However, due to the addition of dipentaerythritol hexaacrylate, the wettability of Application Example 2 on the SUS steel plate and the epoxy molding material is reduced, and the peel strength of Application Example 2 is reduced; and although the peel strength is significantly reduced after UVLED irradiation curing, there is still residual glue on the SUS steel plate and the epoxy molding material.

[0162] In the comparative example 3, isocyanate ethyl acrylate was used to replace the polyurethane monomer containing different active olefin groups prepared in the preparation example 1. The obtained polyacrylate was applied to the UV viscosity-reducing adhesive composition. Although it could form an adhesive layer with a certain cross-linking density through olefin polymerization, the peeling strength was poor and the shrinkage degree of the adhesive layer was low under UVLED irradiation;

[0163] Moreover, in terms of manufacturing cost, ethyl isocyanate acrylate is expensive, with a unit price generally being 1,100 to 1,200 yuan / kg, while the production cost of the polyacrylate containing photocurable alkenyl groups in the side chain prepared in the present application is 35 to 40 yuan / kg; the cost of ethyl isocyanate acrylate is approximately 30 times the cost of the polyacrylate containing photocurable alkenyl groups in the side chain.

[0164] Application Examples 1-5 form a single comparison. The difference between Application Examples 1-5 lies in the different weight ratios of the polyurethane monomers containing different active olefin groups and the hydroxyl- and olefin-terminated acrylate copolymer monomers. The optimal weight ratio of the polyurethane monomers containing different active olefin groups and the hydroxyl- and olefin-terminated acrylate copolymer monomers is 2:1. The prepared polyacrylate has a high content of side chain olefin groups and can form a high cross-linking density adhesive layer after UV irradiation curing. At the same time, the content of flexible segments in the polyacrylate is moderate, which can better wet the material surface, and the peel strength before UV curing is high, which can achieve the UV viscosity-reducing adhesive to have a high bonding performance before UV curing, and the bonding strength is greatly reduced after UV curing.

[0165] Application Example 1, Application Example 11 and Application Example 12 form a single comparison. The difference is that Application Example 11 uses an acrylic leveling agent. Although the acrylic leveling agent can enhance the bonding strength of the UV viscosity-reducing adhesive before UV curing, the peel strength also increases accordingly after UV curing, and the peel strength of the UV viscosity-reducing adhesive after UV curing decreases slightly. In Application Example 12, no silicone leveling agent is used, and the UV viscosity-reducing adhesive has poor wettability to the bonded substrate, resulting in low peel strength before UV curing.

[0166] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0167] Moreover, the above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the attached claims.

Claims

1. A polyacrylate having a photocurable alkenyl group in the side chain, characterized in that: The invention is prepared by reacting the following raw materials in parts by weight: 2 to 5 parts of polyurethane monomers containing different active alkenyl groups, 0.8 to 3 parts of hydroxyl and alkenyl-terminated acrylate copolymer monomers, 80 to 95 parts of flexible monomers, 8 to 15 parts of rigid monomers, 0.1 to 1 parts of thermal initiators and 200 to 290 parts of solvents; The polyurethane monomer containing different active alkenyl groups is prepared by reacting isocyanate, acrylate containing alkenyl and hydroxyl groups, a catalyst and an inhibitor; The hydroxyl and olefinic terminated acrylate comonomer is prepared by copolymerization of primary hydroxy caprolactone oligomer and acrylic acid.

2. The polyacrylate containing a photocurable alkenyl group in the side chain according to claim 1, characterized in that: The flexible monomer is at least one of a long-chain monofunctional acrylate and a non-aromatic carbocyclic monofunctional acrylate; Long-chain monofunctional acrylates include butyl acrylate, isooctyl acrylate, 2-propylheptyl acrylate, and isobutyl acrylate; Non-aromatic carbocyclic monofunctional acrylates include cyclohexyl acrylate.

3. The polyacrylate containing a photocurable alkenyl group in the side chain according to claim 1, characterized in that: The rigid monomer satisfies at least one of the following characteristics: Methyl acrylate, phenyl methacrylate, methacryloyloxyethyl acrylate and phenyl acrylate.

4. A UV viscosity-reducing adhesive composition, characterized in that: The composition comprises the following components in parts by weight: 80-100 parts of the polyacrylate containing photocurable alkenyl groups in the side chains as claimed in any one of claims 1 to 3, 0.05-0.5 parts of a curing agent, 2.5-5 parts of a photoinitiator and 80-100 parts of a diluent.

5. The UV viscosity-reducing adhesive composition according to claim 4, characterized in that: The UV viscosity-reducing adhesive composition also includes a leveling agent, and the weight portion of the leveling agent is 0.01 to 0.05 parts.

6. The UV viscosity-reducing adhesive composition according to claim 5, characterized in that: The leveling agent is an organic silicon leveling agent.

7. The UV viscosity-reducing adhesive composition according to claim 4, characterized in that: The curing agent is at least one of a diisocyanate curing agent and a polyisocyanate curing agent; Diisocyanate curing agents include 2,6-toluene diisocyanate, 1,3,3-trimethyl-5-isocyanato-1-isocyanatomethylcyclohexane, 4,4-dicyclohexylmethane diisocyanate, 1,6-diisocyanatohexane, trimethylhexane diisocyanate and xylylene diisocyanate; Polyisocyanate curing agents include biuret-type polyisocyanates, trimer-type polyisocyanates, and adduct-type polyisocyanates.

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