Composition capable of reducing internal stress of pressure-sensitive adhesive, pressure-sensitive adhesive as well as preparation method and application of pressure-sensitive adhesive

Abstract

The invention relates to the technical field of pressure-sensitive adhesives, in particular to a composition capable of reducing internal stress of a pressure-sensitive adhesive, the pressure-sensitive adhesive and a preparation method and application of the pressure-sensitive adhesive. The invention provides a composition capable of reducing internal stress of a pressure-sensitive adhesive. The composition comprises a (methyl) acrylate polymer, a cross-linking agent and a chain extender, the structural formula of the cross-linking agent is as follows: # imgabs0 #, X represents a residue obtained by removing two isocyanate groups from a polyisocyanate compound, and Y represents a residue obtained by removing active hydrogen atoms from a hydrogen abstracting type photoinitiator containing active hydrogen; the chain extender comprises long-chain polyamine. The composition provided by the invention can greatly reduce and even eliminate the internal stress of the pressure-sensitive adhesive in the use process, and effectively reduces the possible problems of pressure-sensitive adhesive aging, cracking, interface stripping or bubble rebound and the like caused by long-term stress accumulation of an adhesive layer.

Description

Technical Field

[0001] The invention relates to the technical field of pressure-sensitive adhesives, in particular to a composition capable of reducing the internal stress of the pressure-sensitive adhesive, the pressure-sensitive adhesive and a preparation method and application thereof. Background Art

[0002] Pressure-sensitive adhesive (PSA) is a special type of adhesive that can achieve adhesion by applying slight pressure. Its adhesion principle is based on the viscoelastic properties of the material. Pressure-sensitive adhesive changes its own molecular chain morphology and internal stress state through contact deformation caused by external force, and achieves adhesion through the intermolecular force (cohesion) and the adhesion between the substrate. It can be firmly bonded to the adherend without heating or chemical reaction.

[0003] Acrylic pressure-sensitive adhesive is a type of pressure-sensitive adhesive with a wide range of uses and large consumption. It is widely used in many fields such as electronic display, aerospace, automobile manufacturing, and medical and health care due to its many advantages such as high transparency, high adhesion, and excellent aging resistance. However, the performance of pressure-sensitive adhesives will be significantly affected by internal stress in practical applications. Internal stress is the stress that remains in the material during processing or the stress generated by external forces. For example, during the coating, curing, and cooling process of the pressure-sensitive adhesive in the preparation process, residual stress will be generated due to temperature gradient or material shrinkage. During the bonding process of the substrate, the thermal expansion coefficient or elastic modulus of the substrate is different from that of the pressure-sensitive adhesive, which will cause stress at the interface. In some specific usage scenarios, such as the OCA optical adhesive used in curved screens, the mismatch between the bending curvature and the flexibility of the pressure-sensitive adhesive will cause internal stress accumulation, resulting in screen warping, interface peeling or bubbling. Not only that, long-term accumulation of internal stress will also cause the pressure-sensitive adhesive to age and aggravate the degradation of viscoelastic properties, especially under extreme conditions such as high temperature and high humidity. Internal stress has various sources and complex effects. The accumulation of internal stress can also lead to the decline of the adhesion performance of pressure-sensitive adhesives, failure or even destruction. Therefore, it is of great significance to reduce the generation of internal stress as much as possible during use to improve the reliability of pressure-sensitive adhesives.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The object of the present invention is to provide a composition that can reduce the internal stress of a pressure-sensitive adhesive, a pressure-sensitive adhesive, and a preparation method and application thereof. The composition of the present invention can significantly reduce or even eliminate the internal stress of the pressure-sensitive adhesive during use, thereby significantly improving the adhesion performance and service life of the pressure-sensitive adhesive, and improving the reliability of the pressure-sensitive adhesive in scenarios with large internal stress.

[0006] In order to achieve the above-mentioned object of the present invention, the first aspect of the present invention provides a composition capable of reducing the internal stress of a pressure-sensitive adhesive, comprising: a (meth)acrylate polymer, a crosslinking agent and a chain extender;

[0007] The structural formula of the cross-linking agent is as follows:

[0008]

[0009] Wherein, X represents a residue obtained by removing two isocyanate groups from a polyisocyanate compound, and Y represents a residue obtained by removing an active hydrogen atom from a hydrogen abstraction type photoinitiator containing active hydrogen;

[0010] The chain extender includes a long chain polyamine.

[0011] In a specific embodiment of the present invention, X comprises at least one of the following structures:

[0012]

[0013] In a specific embodiment of the present invention, the hydrogen abstraction type photoinitiator comprises at least one of a hydroxyl-containing benzophenone compound, a hydroxyl-containing thioxanthone compound and a hydroxyl-containing anthraquinone compound. Further, Y comprises at least one of the following structures:

[0014]

[0015] In a specific embodiment of the present invention, the (meth) acrylic acid ester polymer is mainly prepared by copolymerization of acrylic acid ester monomers. Further, the (meth) acrylic acid ester polymer has a glass transition temperature Tg≤30°C.

[0016] In a specific embodiment of the present invention, the chain extender is a polyetheramine.

[0017] In a specific embodiment of the present invention, the structural formula of the chain extender is as follows:

[0018]

[0019] Wherein, the weight average molecular weight of the chain extender is 500-2000.

[0020] In a specific embodiment of the present invention, in the composition, the amount of the crosslinking agent is 3 wt % to 5 wt % of the (meth)acrylate polymer.

[0021] In a specific embodiment of the present invention, in the composition, the amount of the chain extender is 5wt% to 10wt% of the (meth)acrylate polymer.

[0022] The second aspect of the present invention provides a pressure-sensitive adhesive, comprising the composition capable of reducing the internal stress of the pressure-sensitive adhesive provided by the first aspect of the present invention.

[0023] The third aspect of the present invention provides a method for preparing the pressure-sensitive adhesive provided by the second aspect of the present invention, comprising the following steps: uniformly mixing the components of the pressure-sensitive adhesive, coating the components on the surface of a release film, and curing the components by light irradiation to obtain the pressure-sensitive adhesive.

[0024] The fourth aspect of the present invention provides an application of the pressure-sensitive adhesive provided in the second aspect of the present invention, comprising the following steps: laminating the pressure-sensitive adhesive to the surface of a substrate to be bonded to obtain a laminating assembly, and heat-treating the laminating assembly.

[0025] In a specific embodiment of the present invention, the heat treatment comprises: heat treatment at 50-70° C. for 30-120 min.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The present invention provides a composition that can reduce the internal stress of a pressure-sensitive adhesive, which can significantly reduce or even eliminate the internal stress to which the pressure-sensitive adhesive is subjected during use, and effectively reduce the possible problems of the pressure-sensitive adhesive caused by long-term stress accumulation, such as aging, cracking, interface peeling or bubble rebound;

[0028] (2) After heat treatment, the pressure-sensitive adhesive prepared using the composition of the present invention forms an interpenetrating network between the crosslinker, the chain extender and the matrix resin, which reduces or even eliminates the internal stress and significantly improves the strength of the pressure-sensitive adhesive, providing support for its promotion in high-demand application scenarios. DETAILED DESCRIPTION

[0029] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments, but it will be appreciated by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work, all belong to the scope of protection of the present invention. If specific conditions are not indicated in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0030] The first aspect of the present invention provides a composition capable of reducing the internal stress of a pressure-sensitive adhesive, comprising: a (meth)acrylate polymer, a crosslinking agent and a chain extender;

[0031] The structural formula of the crosslinking agent is as follows:

[0032]

[0033] Wherein, X represents a residue obtained by removing two isocyanate groups from a polyisocyanate compound, and Y represents a residue obtained by removing an active hydrogen atom from a hydrogen abstraction type photoinitiator containing active hydrogen;

[0034] Chain extenders include long chain polyamines.

[0035] In the composition of the present invention, a cross-linking agent having a hindered urea bond and a hydrogen abstraction type photoinitiator functional group is used in combination with a chain extender and a matrix, which can greatly reduce or even eliminate the internal stress to which the pressure-sensitive adhesive is subjected during use, and effectively reduce possible problems such as aging, cracking, interface peeling or bubble rebound of the pressure-sensitive adhesive caused by long-term stress accumulation of the adhesive layer.

[0036] The crosslinking agent of the present invention contains a special hindered urea bond. During the heat treatment process, the hindered urea bond in the part with greater internal stress will be preferentially broken and regenerated into isocyanate, and then recombined with the chain extender, so as to achieve the effect of reducing or even eliminating the internal stress, and avoid problems such as back foaming caused by the internal stress; and the chain extender and the crosslinking agent will form an interpenetrating network structure with the (meth)acrylate polymer, and after eliminating the internal stress, the strength of the pressure-sensitive adhesive can still be maintained.

[0037] In a specific embodiment of the present invention, X comprises at least one of the following structures:

[0038]

[0039] It should be noted that the wavy line perpendicular to the single bond in the present invention Indicates the position at which the group is attached to the rest of the compound.

[0040] In a specific embodiment of the present invention, the hydrogen abstraction type photoinitiator includes at least one of a hydroxyl-containing benzophenone compound, a hydroxyl-containing thioxanthone compound and a hydroxyl-containing anthraquinone compound. Further, Y includes at least one of the following structures:

[0041]

[0042] In a specific embodiment of the present invention, the cross-linking agent may include at least one of the following structures:

[0043]

[0044] In a specific embodiment of the present invention, the preparation method of the cross-linking agent comprises:

[0045] Compound A undergoes a first urethanization reaction with polyisocyanate to obtain compound B, and then undergoes a second urethanization reaction with a hydrogen abstraction type photoinitiator containing active hydrogen to obtain a crosslinking agent;

[0046] The structural formulas of compound A and compound B are as follows:

[0047]

[0048] In a specific embodiment of the present invention, the polyisocyanate is a diisocyanate, and may further include at least one of isophorone diisocyanate (IPDI) and toluene diisocyanate (TDI).

[0049] In a specific embodiment of the present invention, the hydrogen abstraction type photoinitiator includes at least one of 4-hydroxybenzophenone, 4-(2-hydroxyethoxy)benzophenone and 4-hydroxythioxanthone.

[0050] In a specific embodiment of the present invention, in the first carbamate reaction, the molar ratio of compound A to polyisocyanate is 1: 1. Further, the first carbamate reaction is carried out under the action of a solvent and a catalyst, the solvent includes but is not limited to at least one of ethyl acetate and dichloromethane, and the catalyst includes but is not limited to dibutyltin dilaurate.

[0051] In a specific embodiment of the present invention, the temperature of the first urethanization reaction is 20-30° C., and the reaction time is 2-4 hours.

[0052] In a specific embodiment of the present invention, in the second carbamate reaction, the molar ratio of the hydrogen abstraction type photoinitiator containing active hydrogen to the compound A used in the first carbamate reaction is 1: 1. Further, the second carbamate reaction is carried out under the action of a solvent and a catalyst, the solvent includes but is not limited to ethyl acetate, and the catalyst includes but is not limited to dibutyltin dilaurate.

[0053] In a specific embodiment of the present invention, the temperature of the second urethanization reaction is 45-55° C. The reaction is carried out until completion, and the -NCO groups in the reaction system are characterized by infrared spectroscopy. The reaction is determined to be complete when the peak of the -NCO group disappears under the infrared spectrum.

[0054] In actual operation, no post-treatment is required after the first urethanization reaction, and a hydrogen abstraction type photoinitiator containing active hydrogen is directly added to react at a high temperature. After the reaction is completed, the solvent is removed to obtain a crosslinking agent.

[0055] In a specific embodiment of the present invention, the (meth)acrylate polymer is mainly prepared by copolymerization of acrylate monomers. Further, the (meth)acrylate polymer has a glass transition temperature Tg≤30°C.

[0056] In a specific embodiment of the present invention, the viscosity of the (meth)acrylate polymer obtained by copolymerization is 100-10000 cP, for example, it can be 100 cp, 500 cp, 1000 cp, 3000 cp, 5000 cp, 8000 cp, 10000 cp or any two thereof.

[0057] Among them, the acrylic ester monomers include but are not limited to soft monomers, hard monomers and functional monomers, etc. For example, the soft monomers may include but are not limited to at least one of isooctyl acrylate, ethyl acrylate and butyl acrylate; the hard monomers may include but are not limited to at least one of methyl acrylate, methyl methacrylate and isobornyl methacrylate; the functional monomers may include but are not limited to at least one of glycidyl methacrylate, hydroxyethyl acrylate and hydroxypropyl acrylate.

[0058] In a specific embodiment of the present invention, the acrylic ester monomer includes the following components in parts by weight: 40 to 60 parts of soft monomer, 20 to 40 parts of hard monomer and 15 to 25 parts of functional monomer.

[0059] In a specific embodiment of the present invention, the preparation of the (meth)acrylate polymer further includes an initiator, such as a photoinitiator, wherein the amount of the photoinitiator is 0.01wt% to 0.1wt% of the weight of the acrylate monomer, for example, 0.01wt%, 0.03wt%, 0.05wt%, 0.08wt%, 0.1wt% or any two thereof.

[0060] In a specific embodiment of the present invention, the chain extender is a polyetheramine.

[0061] In a specific embodiment of the present invention, the structural formula of the chain extender is as follows:

[0062]

[0063] The weight average molecular weight of the chain extender is 500 to 2000, for example, 500, 800, 1000, 1200, 1500, 1800, 2000 or any two thereof.

[0064] In a specific embodiment of the present invention, in the composition, the amount of the crosslinking agent is 3wt% to 5wt% of the (meth)acrylate polymer, for example, it can be 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt% or a range composed of any two of them, which is more helpful to take into account both eliminating internal stress and ensuring the strength of the pressure-sensitive adhesive.

[0065] In a specific embodiment of the present invention, in the composition, the amount of the chain extender is 5wt% to 10wt% of the (meth)acrylate polymer, for example, it can be 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt% or a range composed of any two of them, which is more conducive to the coordination of the cross-linking agent and the (meth)acrylate polymer to form a suitable interpenetrating network structure, while eliminating internal stress and improving the strength of the pressure-sensitive adhesive.

[0066] The second aspect of the present invention provides a pressure-sensitive adhesive, comprising the composition capable of reducing the internal stress of the pressure-sensitive adhesive provided by the first aspect of the present invention.

[0067] The composition of the present invention can be used alone or in combination with other slurries such as silicone or polyurethane to prepare a pressure-sensitive adhesive, so as to achieve high strength, high bonding performance, etc. while greatly reducing or even eliminating the internal stress of the pressure-sensitive adhesive.

[0068] In a specific embodiment of the present invention, the pressure-sensitive adhesive further comprises a photoinitiator. Further, the amount of the photoinitiator can be 0.5 wt% to 1 wt% of the composition.

[0069] The third aspect of the present invention provides a method for preparing the pressure-sensitive adhesive provided by the second aspect of the present invention, comprising the following steps: uniformly mixing the components of the pressure-sensitive adhesive, coating the components on the surface of a release film, and curing the components by light irradiation to obtain the pressure-sensitive adhesive.

[0070] Among them, the coating method is not limited, and coating, scraping or dipping coating can be adopted. In actual operation, coating can be applied by an applicator. The release film may include materials such as polyethylene terephthalate (PET) film, polyimide (PI) film, polyethylene (PE) film, oriented stretch polypropylene (OPP) film, composite release film, etc. Since the release film will be peeled off during actual use, the thickness of the release film has little effect on the actual use of the product. The thickness of the release film can be freely selected according to actual needs without special limitation, for example, it can be 25 to 100 μm, specifically 25 μm, 40 μm, 60 μm, 80 μm, 100 μm or any two of them.

[0071] In a specific embodiment of the present invention, the thickness of the pressure-sensitive adhesive is 50-400 μm, for example, 50 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 400 μm or a range consisting of any two thereof.

[0072] In a specific embodiment of the present invention, light radiation curing includes but is not limited to ultraviolet light curing. The specific ultraviolet light curing parameters are conventionally adjusted to ensure curing.

[0073] The fourth aspect of the present invention provides an application of the pressure-sensitive adhesive provided in the second aspect of the present invention, comprising the following steps: laminating the pressure-sensitive adhesive to the surface of a substrate to be bonded to obtain a laminating assembly, and heat-treating the laminating assembly.

[0074] The substrates to be bonded include, but are not limited to, cover glass, interior decorative parts (such as panels, buttons), multi-layer display structures, etc.

[0075] In a specific embodiment of the present invention, the heat treatment includes: heat preservation treatment at 50-70°C for 30-120 minutes. The temperature of the heat preservation treatment can be 50°C, 55°C, 60°C, 65°C, 70°C or any two of them, and the time of the heat preservation treatment can be 30 minutes, 40 minutes, 50 minutes, 60 minutes, 80 minutes, 100 minutes, 120 minutes or any two of them.

[0076] The (meth) acrylate polymer used in the following embodiments can be referred to as follows, but is not limited thereto. The specific preparation method is: 50 parts by weight of isooctyl acrylate, 30 parts by weight of isobornyl methacrylate and 20 parts by weight of hydroxyethyl acrylate are placed in a reaction container, mixed evenly under nitrogen protection, and then 0.05 parts of photoinitiator 184 are added, and bulk polymerization is carried out under ultraviolet light initiation to generate a (meth) acrylate polymer with a viscosity of 1500 cP. The Tg of the (meth) acrylate polymer finally obtained is -5°C.

[0077] Example 1

[0078] This embodiment provides a composition capable of reducing the internal stress of a pressure-sensitive adhesive, comprising the following components by weight: 100 parts of a (meth)acrylate polymer, 3 parts of a crosslinking agent, and 5 parts of polyetheramine FL-1000. The preparation method of the composition comprises: uniformly mixing the components according to a certain proportion.

[0079] The cross-linking agent TBEMA-IPDI-BP of this embodiment has the following structure:

[0080]

[0081] The synthesis route of the cross-linking agent TBEMA-IPDI-BP of the present embodiment is as follows:

[0082]

[0083] Specifically, the preparation method of the cross-linking agent TBEMA-IPDI-BP includes: dissolving isophorone diisocyanate IPDI (111.2 g, 0.5 mol) and 0.2 g of dibutyltin dilaurate (DBTDL) in 100 mL of ethyl acetate (EA), and after replacing nitrogen, using a constant pressure dropping funnel to slowly drip a solution of 2-(tert-butylamino)ethyl methacrylate TBEMA (92.6 g, 0.5 mol) also dissolved in 100 mL of EA into the reaction solution and stirring continuously, and reacting at room temperature for 3 hours under a nitrogen atmosphere after the dropwise addition is completed to obtain TBEMA-IPDI; then adding 4-hydroxybenzophenone (99.2 g, 0.5 mol), setting a condenser reflux tube and reacting at 50 ° C until complete (the reaction is determined to be complete when the peak of the -NCO group in the infrared spectrum disappears completely), and then rotary evaporation to remove the solvent, and finally obtaining the target product cross-linking agent TBEMA-IPDI-BP.

[0084] The structural characterization data of the prepared cross-linking agent TBEMA-IPDI-BP are as follows:

[0085] 1 H NMR(400MHz,Chloroform-d)δ7.89(d,J=7.6Hz,2H),7.85-7.80(m,2H),7.53-7.48(m,3H),7.29(s,1H),7.27(s,1H),5.93(s, 1H),5.78(d,J=12.5Hz,1H),5.53(d,J=12.5Hz,1H),5.38(s,1H),4.34(s,2H),3.72(s,1H),3.50(s,2H),3.35(d,J=12.5Hz,1 H),3.10(d,J=12.5Hz,1H),1.93(s,3H),1.86(d,J=13.0Hz,1H),1.75(d,J=13.0Hz,1H),1.61(d,J=13.0Hz,1H),1.49(d,J=13 .0Hz,1H),1.41(d,J=13.0Hz,1H),1.30(s,9H),1.16(d,J=13.0Hz,1H),1.04(s,3H),0.99(s,3H),0.92(s,3H); HRMS(EI):m / z calcd forC 35 H 47 N3O6: 605.3469[M]+; found: 605.3486; The obtained product was confirmed to be the structure of the target cross-linking agent TBEMA-IPDI-BP.

[0086] Example 2

[0087] This embodiment refers to the composition capable of reducing internal stress of a pressure-sensitive adhesive and the preparation method thereof of Embodiment 1, the only difference being that the type of the crosslinking agent is different.

[0088] The cross-linking agent of this embodiment is TBEMA-TDI-HTX, which has the following structure:

[0089]

[0090] The synthetic route of the cross-linking agent TBEMA-TDI-HTX of the present embodiment is as follows:

[0091]

[0092] Specifically, the preparation method of the cross-linking agent TBEMA-TDI-HTX includes: dissolving toluene diisocyanate TDI (87.1 g, 0.5 mol) and 0.2 g of dibutyltin dilaurate (DBTDL) in 100 mL of dichloromethane (DCM), and after replacing nitrogen, using a constant pressure dropping funnel to slowly drip a solution of 2-(tert-butylamino)ethyl methacrylate TBEMA (92.6 g, 0.5 mol) also dissolved in 100 mL of DCM into the reaction solution and stirring continuously, and reacting at room temperature for 3 hours under a nitrogen atmosphere after the dropwise addition is completed to obtain TBEMA-TDI; then adding a certain amount of 4-hydroxythioxanthone (114 g, 0.5 mol), setting a condensation reflux tube and reacting at 50° C. until complete (the reaction is determined to be complete when the peak of the -NCO group in the infrared spectrum disappears completely), and then rotary evaporation to remove the solvent, and finally obtaining the target product cross-linking agent TBEMA-TDI-HTX.

[0093] The structural characterization data of the prepared cross-linking agent TBEMA-TDI-HTX are as follows:

[0094] HRMS(EI):m / z calcd for C 32 H 33 N3O6S:587.2090[M]+; found:587.2099; The obtained product was confirmed to have the structure of the target cross-linking agent TBEMA-TDI-HTX.

[0095] Example 3

[0096] This embodiment refers to the composition capable of reducing the internal stress of a pressure-sensitive adhesive and the preparation method thereof of Embodiment 1, the only difference being that the amount of each component used is different.

[0097] The composition capable of reducing the internal stress of a pressure-sensitive adhesive of this embodiment includes the following components in parts by weight: 100 parts of a (meth)acrylate polymer, 5 parts of a cross-linking agent, and 10 parts of polyetheramine FL-1000.

[0098] Example 4

[0099] This embodiment refers to the composition capable of reducing the internal stress of a pressure-sensitive adhesive and the preparation method thereof of Embodiment 1, the only difference being that the amount of each component used is different.

[0100] The composition capable of reducing the internal stress of a pressure-sensitive adhesive of this embodiment includes the following components in parts by weight: 100 parts of a (meth)acrylate polymer, 1 part of a cross-linking agent, and 3 parts of polyetheramine FL-1000.

[0101] Example 5

[0102] This embodiment refers to the composition capable of reducing the internal stress of a pressure-sensitive adhesive and the preparation method thereof of Embodiment 1, the only difference being that the amount of each component used is different.

[0103] The composition capable of reducing the internal stress of a pressure-sensitive adhesive of this embodiment includes the following components in parts by weight: 100 parts of a (meth)acrylate polymer, 6 parts of a cross-linking agent, and 12 parts of polyetheramine FL-1000.

[0104] Embodiments 6 to 10

[0105] Examples 6 to 10 provide a method for preparing a pressure-sensitive adhesive, comprising the following steps: weighing a composition that can reduce the internal stress of the pressure-sensitive adhesive and a photoinitiator 184 at a mass ratio of 108:1, mixing them evenly, coating them between light and heavy release films, and then curing them with a low-pressure mercury lamp for 5 minutes to form a 200 μm thick OCA optical pressure-sensitive adhesive.

[0106] Examples 6 to 10 respectively correspond to the compositions for reducing the internal stress of the pressure-sensitive adhesive of Examples 1 to 5.

[0107] Comparative Example 1

[0108] Comparative Example 1 refers to the pressure-sensitive adhesive and preparation method thereof of Example 6, except that an equal weight composition is used to replace the composition capable of reducing the internal stress of the pressure-sensitive adhesive of Example 1.

[0109] The composition of Comparative Example 1 refers to the composition of Example 1 and its preparation method, except that the crosslinking agent TBEMA-IPDI-BP in Example 1 is replaced by an equal weight of 1,6-hexanediol diacrylate.

[0110] Experimental example

[0111] The bonding component samples made of the pressure-sensitive adhesives prepared in Examples 6 to 10 and Comparative Example 1 were placed in a high / low temperature test chamber, a hot and cold shock test chamber, and a double 85 constant temperature and humidity test chamber to verify the reliability of the pressure-sensitive adhesives, and the gel rate test and peel force test were performed on each pressure-sensitive adhesive. The test results are shown in Table 1.

[0112] The preparation of the bonded component sample includes: bonding the pressure-sensitive adhesives prepared in Examples 6 to 10 and Comparative Example 1 to the same curved cover glass respectively, degassing at room temperature, and then heat-treating at 60° C. for 60 minutes to obtain the bonded component sample.

[0113] High temperature test box: Place the bonded component samples in a 105℃ high temperature test box for 500 hours, take them out and observe whether there are wrinkles or bubbles;

[0114] Low temperature test box: Place the bonded component samples in a -40℃ low temperature test box for 500 hours, take them out and observe whether there are wrinkles or bubbles;

[0115] Thermal shock test chamber: Place the bonded component specimens in a thermal shock test chamber and cycle 500 times at -40°C (30 min) to 85°C (30 min);

[0116] Double 85 constant temperature and humidity test chamber: Place the bonded component samples in a constant temperature and humidity test chamber at 85℃ / 85% humidity for 500 hours, take them out and observe whether there are wrinkles or bubbles;

[0117] Gel rate test: Take a certain size of pressure-sensitive adhesive and weigh it as m1, immerse it completely in ethyl acetate for 24 hours, then filter it with a 400-mesh filter and wash it, dry it in a 120℃ oven for 30 minutes, and then weigh it to get the mass m2. Calculate m2 / m1 to get the gel rate;

[0118] Peel strength test: After directly attaching different pressure-sensitive adhesives to standard steel plates, place them at room temperature for 30 minutes to allow the pressure-sensitive adhesive to fully wet the substrate, and then degasse them in a degassing machine at 60°C for 30 minutes, and then test the peel strength according to the test method for peel strength of adhesive tapes in GB2792-2014.

[0119] Table 1 Test results of different pressure-sensitive adhesives

[0120]

[0121]

[0122] From the above test results, it can be seen that the pressure-sensitive adhesive prepared by the composition of the present invention has no appearance problems caused by internal stress such as micro-wrinkles and micro-bubbles in the low-temperature test box, the hot and cold shock test box, and the double 85 constant temperature and humidity test box. Only a small amount of micro-bubbles appear in the 105°C high-temperature test box, which shows that the composition of the present invention has achieved the effect of reducing or even eliminating internal stress, and can avoid the problem of back-bubbling caused by internal stress. At the same time, the interpenetrating network formed improves the reliability of the bonding component and achieves the effect of extending the life of the device. In addition, the gel rate of the pressure-sensitive adhesive of the present invention is significantly improved, which further shows that the pressure-sensitive adhesive of the present invention has better anti-shear drop performance, and also proves the formation of the interpenetrating network.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composition capable of reducing internal stress of a pressure-sensitive adhesive, characterized in that: include: (Meth)acrylate polymers, crosslinking agents and chain extenders; The structural formula of the cross-linking agent is as follows: Wherein, X represents a residue obtained by removing two isocyanate groups from a polyisocyanate compound, and Y represents a residue obtained by removing an active hydrogen atom from a hydrogen abstraction type photoinitiator containing active hydrogen; The chain extender includes a long chain polyamine.

2. The composition for reducing internal stress of a pressure-sensitive adhesive according to claim 1, characterized in that: X includes at least one of the following structures:

3. The composition for reducing internal stress of a pressure-sensitive adhesive according to claim 1, characterized in that: The hydrogen abstraction type photoinitiator comprises at least one of a hydroxyl-containing benzophenone compound, a hydroxyl-containing thioxanthone compound and a hydroxyl-containing anthraquinone compound.

4. The composition for reducing internal stress of a pressure-sensitive adhesive according to claim 1, characterized in that: The (meth) acrylic acid ester polymer is mainly prepared by copolymerization of acrylic acid ester monomers; The (meth)acrylate polymer has a glass transition temperature Tg≤30°C.

5. The composition for reducing internal stress of a pressure-sensitive adhesive according to claim 1, characterized in that: The chain extender is a polyetheramine; The structural formula of the chain extender is as follows: Wherein, the weight average molecular weight of the chain extender is 500-2000.

6. The composition for reducing internal stress of a pressure-sensitive adhesive according to claim 1, characterized in that: In the composition, the amount of the crosslinking agent is 3wt% to 5wt% of the (meth)acrylate polymer.

7. The composition for reducing internal stress of a pressure-sensitive adhesive according to claim 1, characterized in that: In the composition, the amount of the chain extender is 5wt% to 10wt% of the (meth)acrylate polymer.

8. A pressure-sensitive adhesive, characterized in that: A composition capable of reducing the internal stress of a pressure-sensitive adhesive as claimed in any one of claims 1 to 7.

9. The method for preparing the pressure-sensitive adhesive according to claim 8, characterized in that: The method comprises the following steps: uniformly mixing various components of the pressure-sensitive adhesive, coating the components on the surface of the release film, and curing the components by light irradiation to obtain the pressure-sensitive adhesive.

10. The use of the pressure-sensitive adhesive according to claim 8, characterized in that: The method comprises the following steps: laminating the pressure-sensitive adhesive to the surface of the substrate to be bonded to obtain a laminating assembly, and subjecting the laminating assembly to heat treatment; The heat treatment comprises: heat preservation treatment at 50-70° C. for 30-120 minutes.

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