Silicone rubber attached organic silicon pressure-sensitive adhesive as well as preparation method and application of silicone rubber attached organic silicon pressure-sensitive adhesive

Abstract

The invention relates to the technical field of pressure-sensitive adhesives, in particular to an organic silicon pressure-sensitive adhesive attached to silicon rubber as well as a preparation method and application of the organic silicon pressure-sensitive adhesive. The organic silicon pressure-sensitive adhesive is prepared from the following raw materials in parts by weight: 300 parts of vinyl-terminated polydimethylsiloxane, 300 to 500 parts of a reaction product B of hydroxyl-terminated polydimethylsiloxane and boron-containing MTQ silicon resin, 3 parts of a cross-linking agent, 450 parts of MQ silicon resin, 2 parts of an inhibitor, 8 parts of a catalyst and 1500 parts of a solvent. The organic silicon pressure-sensitive adhesive disclosed by the invention is coated on a PET (Polyethylene Terephthalate) base material and is adhered to silicon rubber at normal temperature after being cured, so that cohesive failure of the silicon rubber can be achieved, and the technical problems of insufficient adhesive force, poor heat resistance and the like when the traditional organic silicon pressure-sensitive adhesive is adhered to the silicon rubber are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure-sensitive adhesives, and in particular to an organic silicon pressure-sensitive adhesive for bonding silicone rubber, and a preparation method and application thereof. Background Art

[0002] The existing PET protective film is mainly used to pre-treat the silicone rubber with a backing agent, and then the PET protective film is laminated after the surface is dry. Generally, the strongest bonding effect is achieved after being left at room temperature for 4-12 hours. Although silicone pressure-sensitive adhesive technology has made significant progress, there are still the following technical problems when laminating silicone rubber:

[0003] Due to the low surface energy and weak polarity of silicone rubber, silicone pressure-sensitive adhesives are prone to problems such as weak adhesion and easy falling off during the bonding process; this not only affects the service life of the product, but also increases production costs. Traditional silicone pressure-sensitive adhesives often require the use of a large amount of solvents and additives during the preparation process, resulting in high VOC emissions, which does not meet the requirements of current environmental regulations. Moreover, under extreme climatic conditions, such as high temperature, low temperature, and humidity, the bonding and physical properties of silicone pressure-sensitive adhesives are easily affected, resulting in reduced product performance.

[0004] Patent 115838477A discloses a borosiloxane polymer, which is prepared at high temperature using octamethylcyclotetrasiloxane, cyclosiloxane, alkali rubber, boric acid or boric acid ester as raw materials. The prepared composition has a tensile strength of 4MPa to 6MPa after radiation curing, but the adhesion to silicone rubber is not mentioned.

[0005] Patent US7312296B2 discloses an organic silicone adhesive, which comprises a condensation reaction product B of a hydroxyl-terminated polydimethylsiloxane and a hydroxyl-containing MQ silicone resin, an alkoxy- and epoxy-containing silane coupling agent, and a crosslinking agent. The prepared composition has good bonding strength to stainless steel sheets, aluminum sheets, silicon sheets, and glass sheets after curing, but does not involve bonding to silicone rubber.

[0006] Patent CN108531123A discloses a boron-modified MQ silicone tackifier silicone pressure-sensitive adhesive, which is composed of a combination of vinyl-terminated polydimethylsiloxane, hydrogen-containing polydimethylsiloxane, MQ silicone resin and boron-modified MQ silicone resin. The protective film prepared therefrom has a silicone rubber peel strength of 890g / 25mm, which does not reach the cohesive failure of the silicone rubber.

[0007] To this end, the present application provides a silicone pressure-sensitive adhesive for bonding silicone rubber, and a preparation method and application thereof. Summary of the invention

[0008] The present application provides a silicone pressure-sensitive adhesive for bonding silicone rubber, and a preparation method and application thereof. The silicone pressure-sensitive adhesive is prepared by mixing a reaction product B of vinyl-terminated polydimethylsiloxane, hydroxyl-terminated polydimethylsiloxane and boron-containing MTQ silicone resin, a cross-linking agent, MQ silicone resin, an inhibitor, a platinum catalyst and a solvent. The silicone pressure-sensitive adhesive composition is coated on a PET substrate and bonded to silicone rubber at room temperature after curing, thereby achieving cohesive failure of the silicone rubber, thereby solving the technical problems of insufficient adhesion and poor heat resistance of traditional silicone pressure-sensitive adhesives when bonding to silicone rubber.

[0009] The technical solution adopted by this application to solve its technical problem is:

[0010] In a first aspect, the present application provides a silicone pressure-sensitive adhesive for bonding silicone rubber, comprising the following raw materials in parts by weight:

[0011] 300 parts of vinyl-terminated polydimethylsiloxane, 300-500 parts of the reaction product B of hydroxyl-terminated polydimethylsiloxane and boron-containing MTQ silicone resin, 3 parts of a crosslinking agent, 450 parts of an MQ silicone resin, 2 parts of an inhibitor, 8 parts of a catalyst, and 1500 parts of a solvent;

[0012] The hydroxyl-terminated polydimethylsiloxane has a molecular weight of 300,000 to 600,000;

[0013] The boron-containing MTQ silicone resin has a number average molecular weight Mn of 2000 to 20000 g / mol;

[0014] The boron-containing MTQ silicone resin is a reaction product B of boric acid ester, ethyl orthosilicate and hexamethyldisiloxane; the boric acid ester is any one of triethyl borate, tripropyl borate and tributyl borate.

[0015] In some specific embodiments, the vinyl terminated polydimethylsiloxane has a molecular weight of 600,000 to 800,000.

[0016] In some specific embodiments, in the boron-containing MTQ silicone resin, the molar ratio of M / T / Q is 0.8 / 0.5 / 1.0 to 0.8 / 1.0 / 1.0.

[0017] In some specific embodiments, the crosslinking agent is polydimethylsiloxane with a hydrogen mass fraction of 1.6%.

[0018] In some specific embodiments, in the MQ silicone resin, the M / Q ratio is 0.7-0.8, and the number average molecular weight is 3000-5000 g / mol.

[0019] In some embodiments, the inhibitor is ethynyl cyclohexanol.

[0020] In some specific embodiments, the catalyst is a platinum catalyst; the platinum catalyst is a Custer catalyst, and the platinum content in the Custer catalyst is 5000 ppm.

[0021] In some specific embodiments, the solvent is any one or more of toluene, xylene, ethyl acetate, and butyl acetate.

[0022] In a second aspect, the present application provides a method for preparing a silicone pressure-sensitive adhesive for bonding silicone rubber as described in the first aspect, comprising the following steps:

[0023] In a reactor, 300 parts of vinyl-terminated polydimethylsiloxane, 300-500 parts of a reaction product B of hydroxyl-terminated polydimethylsiloxane and boron-containing MTQ silicone resin, 3 parts of a crosslinking agent, 450 parts of MQ silicone resin, 2 parts of an inhibitor, 8 parts of a platinum catalyst, and 1500 parts of a solvent are added; the mixture is mixed at room temperature to obtain a silicone pressure-sensitive adhesive.

[0024] In a third aspect, the present application provides an application of an organosilicon pressure-sensitive adhesive, wherein the organosilicon pressure-sensitive adhesive described in the first aspect or the organosilicon pressure-sensitive adhesive prepared by the preparation method described in the second aspect is coated on a substrate and, after curing, bonded to silicone rubber.

[0025] The beneficial effects of this application are:

[0026] The organic silicon pressure-sensitive adhesive described in the present application has excellent adhesion, heat resistance, aging resistance and chemical resistance, and can meet the application requirements in various complex environments. At the same time, the preparation method of the organic silicon pressure-sensitive adhesive also has the advantages of simple preparation process and low cost, and has high industrial application value. DETAILED DESCRIPTION

[0027] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0028] In this application, the term "and / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0029] In the present application, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all represent: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple, respectively.

[0030] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution, some or all of the steps can be executed in parallel or sequentially, and the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0031] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0032] The weight of the relevant components mentioned in the embodiment description of the present application can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the embodiment description of the present application, it is within the scope disclosed in the embodiment description of the present application. Specifically, the mass described in the embodiment description of the present application can be a mass unit known in the chemical industry such as μg, mg, g, kg, etc.

[0033] The terms "first" and "second" are used only for descriptive purposes to distinguish objects such as substances from each other, and should not be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. For example, without departing from the scope of the embodiments of the present application, the first XX may also be referred to as the second XX, and similarly, the second XX may also be referred to as the first XX. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0034] Terminology explanation:

[0035] Karstedt catalyst: Karstedt catalyst is used to promote hydrosilylation reaction.

[0036] Cohesive failure: refers to the phenomenon in which the internal structure of the material is destroyed rather than the separation of the bonding interface.

[0037] Interface failure: refers to the situation where separation occurs at the interface between the adhesive material and the adherend.

[0038] MTQ silicone resin: In this application, it refers to a silicone resin with three functional groups of methyl, phenyl and vinyl, which is used to improve the adhesion and heat resistance of pressure-sensitive adhesives.

[0039] Boron-containing MTQ silicone resin: In this application, boron element is introduced on the basis of MTQ silicone resin to improve the heat resistance and aging resistance of the pressure-sensitive adhesive and enhance the adhesion between the pressure-sensitive adhesive and silicone rubber.

[0040] The present application provides a silicone pressure-sensitive adhesive for bonding silicone rubber, comprising the following raw materials in parts by weight:

[0041] 300 parts of vinyl-terminated polydimethylsiloxane, 300-500 parts of the reaction product B of hydroxyl-terminated polydimethylsiloxane and boron-containing MTQ silicone resin, 3 parts of a crosslinking agent, 450 parts of an MQ silicone resin, 2 parts of an inhibitor, 8 parts of a catalyst, and 1500 parts of a solvent;

[0042] The hydroxyl-terminated polydimethylsiloxane has a molecular weight of 300,000 to 600,000;

[0043] The boron-containing MTQ silicone resin has a number average molecular weight Mn of 2000 to 20000 g / mol;

[0044] The boron-containing MTQ silicone resin is a reaction product B of boric acid ester, ethyl orthosilicate and hexamethyldisiloxane; the boric acid ester is any one of triethyl borate, tripropyl borate and tributyl borate.

[0045] In some embodiments, the vinyl terminated polydimethylsiloxane has a molecular weight of 600,000 to 800,000 and a vinyl content of 0.1-0.2%; for example, the vinyl terminated polydimethylsiloxane can be selected with a molecular weight of any value among 600,000, 610,000, 650,000, 700,000, 710,000, 750,000, and 800,000, preferably 600,000 to 700,000.

[0046] In some embodiments, in the boron-containing MTQ silicone resin, the molar ratio of M / T / Q is 0.8 / 0.5 / 1.0 to 0.8 / 1.0 / 1.0.

[0047] Specifically, the preparation method of the boron-containing MTQ silicone resin comprises the following steps:

[0048] In a 1000ml round-bottom flask, add 30-60 parts of borate, 200 parts of ethyl orthosilicate, 80 parts of hexamethyldisiloxane and 20 parts of ethanol, stir evenly and heat to 40°C; mix 50 parts of deionized water and 30 parts of hydrochloric acid evenly and add dropwise to the mixture within 1 hour. After the addition is complete, heat to 80°C and react for 3 hours. Add xylene to extract the resin, cool to room temperature to separate the acid water, wash the organic phase with water for 3 times, heat the washed organic phase under reduced pressure to obtain solution-type MTQ borosilicate resin SiB.

[0049] The reaction product B of hydroxyl-terminated polydimethylsiloxane and boron-containing MTQ silicone resin is prepared by a method comprising the following steps:

[0050] In a 2000 ml round-bottom flask, add 100 parts of hydroxyl-terminated polydimethylsiloxane, 100-200 parts of boron-containing MTQ silicone resin, 200-600 parts of solvent, and 0.1 part of benzenesulfonic acid, heat to 80° C., react for 4 hours, and cool to room temperature to obtain application product B.

[0051] The molecular weight of the hydroxyl-terminated polydimethylsiloxane may be any value among 300,000, 310,000, 330,000, 350,000, 370,000, 400,000, 410,000, 430,000, 450,000, 470,000, 500,000, 510,000, 530,000, 550,000, 570,000, and 600,000, preferably 400,000 to 500,000.

[0052] In some embodiments, the crosslinking agent is polydimethylsiloxane with a hydrogen mass fraction of 1.6%.

[0053] In some embodiments, in the MQ silicone resin, the M / Q ratio is 0.7-0.8, the number average molecular weight is 3000-5000 g / mol, and the number average molecular weight in the MQ silicone resin can be any value of 3000 g / mol, 3500 g / mol, 4000 g / mol, 4500 g / mol, and 5000 g / mol.

[0054] In some embodiments, the inhibitor is ethynylcyclohexanol.

[0055] In some embodiments, the catalyst is a platinum catalyst; the platinum catalyst is a Custer catalyst, and the platinum content in the Custer catalyst is 5000 ppm.

[0056] In some embodiments, the solvent is any one or more of toluene, xylene, ethyl acetate, and butyl acetate.

[0057] Specifically, in the present application, the addition of 300 parts of vinyl-terminated polydimethylsiloxane can provide adhesion and flexibility, react with the boron-containing MTQ silicone resin to form a cross-linked network, and enhance the overall performance of the pressure-sensitive adhesive; if the weight of the vinyl-terminated polydimethylsiloxane exceeds 300 parts, the pressure-sensitive adhesive may be too soft, the cohesive strength may be reduced, and the adhesion may be affected; if the weight of the vinyl-terminated polydimethylsiloxane is less than 300 parts, the pressure-sensitive adhesive may be hardened, the viscosity may be reduced, and the bonding effect may be poor.

[0058] In the present application, 300-500 parts of the reaction product B of hydroxyl-terminated polydimethylsiloxane and boron-containing MTQ silicone resin can increase the adhesion of the pressure-sensitive adhesive to the surface of the silicone rubber and improve the heat resistance and aging resistance; if the reaction product B is too much, the pressure-sensitive adhesive will become too viscous and difficult to apply, and the internal cross-linking structure may be weakened; if the reaction product B is insufficient, it will be difficult to form an effective cross-linking network, reducing adhesion and durability.

[0059] In this application, 3 parts of cross-linking agent can promote the cross-linking reaction between silicone polymers and improve the cohesive strength and temperature resistance of the pressure-sensitive adhesive; if the cross-linking agent is too much, it may cause excessive cross-linking, causing the pressure-sensitive adhesive to harden and lose the necessary elasticity and viscosity. If the cross-linking agent is insufficient, the cross-linking is insufficient, which may cause the pressure-sensitive adhesive to fail at high temperature or after long-term use.

[0060] In this application, 450 parts of MQ silicone resin can improve the thixotropy and leveling of the pressure-sensitive adhesive, while enhancing chemical resistance and weather resistance; too much MQ silicone resin may increase the cost and change the rheological properties of the pressure-sensitive adhesive, making it difficult to apply. Too little MQ silicone resin cannot provide sufficient filling and support, affecting the physical properties of the final product.

[0061] In this application, 2 parts of the inhibitor can slow down the crosslinking reaction and prevent premature curing during storage. If the inhibitor is too much, the inhibitory effect is too strong and may hinder the normal curing process. If the inhibitor is insufficient, premature curing cannot be effectively prevented and the shelf life is shortened.

[0062] In this application, 8 parts of catalyst can accelerate the crosslinking reaction and ensure that the pressure-sensitive adhesive can be cured within a suitable time. If the catalyst is too much, the catalytic speed is too fast, which may cause local overheating or bubbles, affecting product quality. If the catalyst is insufficient, the curing speed is slow, which prolongs the production cycle and increases costs.

[0063] The method for preparing the silicone pressure-sensitive adhesive bonded to silicone rubber described above comprises the following steps:

[0064] In the reactor, 300 parts of vinyl-terminated polydimethylsiloxane,

[0065] 300-500 parts of a reaction product B of hydroxyl-terminated polydimethylsiloxane and boron-containing MTQ silicone resin, 3 parts of a crosslinking agent, 450 parts of an MQ silicone resin, 2 parts of an inhibitor, 8 parts of a platinum catalyst, and 1500 parts of a solvent are mixed at room temperature to obtain an organic silicone pressure-sensitive adhesive.

[0066] In addition, the present application provides an application of an organic silicone pressure-sensitive adhesive, wherein the organic silicone pressure-sensitive adhesive is coated on a substrate and, after being cured, bonded to the silicone rubber.

[0067] Specifically, the above-mentioned silicone pressure-sensitive adhesive is coated on a PET substrate, and after curing, the silicone rubber is laminated at room temperature to achieve the effect of cohesive failure of the silicone rubber.

[0068] The present application further describes the silicone pressure-sensitive adhesive described in the present application through the following preparation examples, embodiments and comparative examples.

[0069] Preparation Example 1

[0070] The synthesis of MTQ silicone resin includes the following steps:

[0071] In a 1000ml round-bottom flask, add 35 parts of triethyl borate, 200 parts of ethyl orthosilicate, 80 parts of hexamethyldisiloxane and 20 parts of ethanol, stir well and heat to 40°C; mix 50 parts of deionized water and 30 parts of hydrochloric acid well and add dropwise to the mixture within 1 hour. After the addition is complete, heat to 80°C and react for 3 hours. Add xylene to extract the resin, cool to room temperature to separate the acid water, wash the organic phase with water for 3 times, heat the washed organic phase under reduced pressure to obtain solution-type MTQ borosilicate resin SiB-1.

[0072] Preparation Example 2

[0073] The synthesis of MTQ silicone resin includes the following steps:

[0074] In a 1000ml round-bottom flask, add 45 parts of triethyl borate, 200 parts of ethyl orthosilicate, 80 parts of hexamethyldisiloxane and 20 parts of ethanol, stir well and heat to 40°C; mix 50 parts of deionized water and 30 parts of hydrochloric acid well and add dropwise to the mixture within 1 hour. After the addition is complete, heat to 80°C and react for 3 hours. Add xylene to extract the resin, cool to room temperature to separate the acid water, wash the organic phase with water for 3 times, heat the washed organic phase under reduced pressure to obtain solution-type MTQ borosilicate resin SiB-2.

[0075] Preparation Example 3

[0076] The synthesis of reaction product B comprises the following steps:

[0077] In a 2000 ml round-bottom flask, add 100 parts of hydroxyl-terminated polydimethylsiloxane with a molecular weight of 600,000, 150 parts of boron-containing MTQ silicone resin SiB-1, 250 parts of xylene, and 0.1 parts of benzenesulfonic acid, heat to 80°C, react for 4 hours, and cool to room temperature to obtain B-1.

[0078] Preparation Example 4

[0079] The synthesis of reaction product B comprises the following steps:

[0080] In a 2000 ml round-bottom flask, add 100 parts of hydroxyl-terminated polydimethylsiloxane with a molecular weight of 600,000, 200 parts of boron-containing MTQ silicone resin SiB-1, 300 parts of xylene, and 0.15 parts of benzenesulfonic acid, heat to 80°C, react for 4 hours, and cool to room temperature to obtain B-2.

[0081] Preparation Example 5

[0082] The synthesis of reaction product B comprises the following steps:

[0083] In a 2000 ml round-bottom flask, add 100 parts of hydroxyl-terminated polydimethylsiloxane with a molecular weight of 650,000, 100 parts of boron-containing MTQ silicone resin SiB-2, 300 parts of xylene, and 0.15 parts of benzenesulfonic acid, heat to 80°C, react for 4 hours, and cool to room temperature to obtain B-3.

[0084] Preparation Example 6

[0085] The synthesis of reaction product B comprises the following steps:

[0086] In a 2000 ml round-bottom flask, add 100 parts of hydroxyl-terminated polydimethylsiloxane with a molecular weight of 650,000, 200 parts of boron-containing MTQ silicone resin SiB-2, 300 parts of xylene, and 0.15 parts of benzenesulfonic acid, heat to 80°C, react for 4 hours, and cool to room temperature to obtain B-4.

[0087] Example 1

[0088] The preparation method of the organosilicon pressure-sensitive adhesive comprises the following steps:

[0089] In a 5L planetary mixer, add 300 parts of vinyl-terminated polydimethylsiloxane (molecular weight 600,000, vinyl content 0.1%), 500 parts of reaction product B-1, 3 parts of cross-linking agent, 450 parts of MQ silicone resin (M / Q ratio 0.8, number average molecular weight 5000 g / mol), 2 parts of inhibitor, 8 parts of platinum catalyst, 1500 parts of xylene, and stir at room temperature for 120 minutes to obtain a pressure-sensitive adhesive composition S-1.

[0090] Example 2

[0091] The preparation method of the organosilicon pressure-sensitive adhesive comprises the following steps:

[0092] In a 5L planetary mixer, add 300 parts of vinyl-terminated polydimethylsiloxane (molecular weight 600,000, vinyl content 0.1%), 500 parts of reaction product B-2, 3 parts of cross-linking agent, 450 parts of MQ silicone resin (M / Q ratio 0.8, number average molecular weight 5000 g / mol), 2 parts of inhibitor, 8 parts of platinum catalyst, 1500 parts of xylene, and stir at room temperature for 120 minutes to obtain a pressure-sensitive adhesive composition S-2.

[0093] Example 3

[0094] The preparation method of the organosilicon pressure-sensitive adhesive comprises the following steps:

[0095] In a 5L planetary mixer, add 300 parts of vinyl-terminated polydimethylsiloxane (molecular weight 600,000, vinyl content 0.1%), 500 parts of reaction product B-3, 3 parts of cross-linking agent, 450 parts of MQ silicone resin (M / Q ratio 0.8, number average molecular weight 5000 g / mol), 2 parts of inhibitor, 8 parts of platinum catalyst, 1500 parts of xylene, and stir at room temperature for 120 minutes to obtain a pressure-sensitive adhesive composition S-3.

[0096] Example 4

[0097] The preparation method of the organosilicon pressure-sensitive adhesive comprises the following steps:

[0098] In a 5L planetary mixer, add 300 parts of vinyl-terminated polydimethylsiloxane (molecular weight 600,000, vinyl content 0.1%), 300 parts of reaction product B-4, 3 parts of cross-linking agent, 450 parts of MQ silicone resin (M / Q ratio 0.8, number average molecular weight 5000 g / mol), 2 parts of inhibitor, 8 parts of platinum catalyst, 1500 parts of xylene, and stir at room temperature for 120 minutes to obtain a pressure-sensitive adhesive composition S-4.

[0099] Example 5

[0100] The preparation method of the organosilicon pressure-sensitive adhesive comprises the following steps:

[0101] In a 5L planetary mixer, add 300 parts of vinyl-terminated polydimethylsiloxane (molecular weight 600,000, vinyl content 0.1%), 500 parts of reaction product B-4, 3 parts of cross-linking agent, 450 parts of MQ silicone resin (M / Q ratio 0.8, number average molecular weight 5000 g / mol), 2 parts of inhibitor, 8 parts of platinum catalyst, 1500 parts of xylene, and stir at room temperature for 120 minutes to obtain a pressure-sensitive adhesive composition S-5.

[0102] Comparative Example 1

[0103] The preparation method of the organosilicon pressure-sensitive adhesive comprises the following steps:

[0104] In a 5L planetary mixer, 300 parts of vinyl-terminated polydimethylsiloxane (molecular weight 600,000, vinyl content 0.1%), 500 parts of hydroxy polydimethylsiloxane with a molecular weight of 600,000, 3 parts of a crosslinking agent, 450 parts of MQ silicone resin (M / Q ratio 0.8, number average molecular weight 5000 g / mol), 2 parts of an inhibitor, 8 parts of a platinum catalyst, and 1500 parts of xylene were added and stirred at room temperature for 120 minutes to obtain a pressure-sensitive adhesive composition CS-1.

[0105] Comparative Example 2

[0106] The preparation method of the organosilicon pressure-sensitive adhesive comprises the following steps:

[0107] In a 5L planetary mixer, 300 parts of vinyl-terminated polydimethylsiloxane (molecular weight 600,000, vinyl content 0.1%), 500 parts of SiB-1, 3 parts of a crosslinking agent, 450 parts of MQ silicone resin (M / Q ratio 0.8, number average molecular weight 5000 g / mol), 2 parts of an inhibitor, 8 parts of a platinum catalyst, and 1500 parts of xylene were added and stirred at room temperature for 120 minutes to obtain a pressure-sensitive adhesive composition CS-2.

[0108] Comparative Example 3

[0109] The preparation method of the organosilicon pressure-sensitive adhesive comprises the following steps:

[0110] In a 5L planetary mixer, 300 parts of vinyl-terminated polydimethylsiloxane (molecular weight 600,000, vinyl content 0.1%), 200 parts of reaction product B-1, 3 parts of a crosslinking agent, 450 parts of MQ silicone resin (M / Q ratio 0.8, number average molecular weight 5000 g / mol), 2 parts of an inhibitor, 8 parts of a platinum catalyst, and 1500 parts of xylene were added and stirred at room temperature for 120 minutes to obtain a pressure-sensitive adhesive composition CS-3.

[0111] The pressure-sensitive adhesive compositions S-1 to S-5 of the examples and CS-1 to CS-3 of the comparative examples were coated on a PET substrate with a thickness of 50 μm using a wire rod, and cured at 140°C for 2 minutes to obtain a PET protective film with a dry adhesive thickness of 30 μm. Then, the film was laminated with silicone rubber and placed at room temperature for 24 hours to test the bonding effect, as shown in Table 1. The product data test method in Table 1 is as follows:

[0112] The hardness of silicone rubber is measured by a Shore A durometer; cohesive failure is the cohesive failure of silicone rubber when peeled at 180° after hot pressing; interface failure is the separation of the PET protective film and silicone rubber interface when peeled at 180°;

[0113] Table 1

[0114]

[0115]

[0116] As can be seen from Table 1: By comparing the embodiments with the comparative examples, it can be found that the embodiments of the present invention can achieve cohesive failure of silicone rubber for hot pressing of 20A to 40A silicone rubber, partially achieve cohesive failure of 50A silicone rubber, and fail to achieve cohesive failure of 60A;

[0117] In Comparative Example 1, the silicone pressure-sensitive adhesive did not use the reaction product B of hydroxyl-terminated polydimethylsiloxane and boron-containing MTQ silicone resin. All test samples showed "interface failure", that is, the bonding force between the PET protective film and the silicone rubber was insufficient and cohesive failure could not be achieved.

[0118] Comparative Example 2, the silicone pressure-sensitive adhesive, only used the boron-containing MTQ silicone resin SiB-1 without forming the reaction product B. Similarly, all test results were "interface damage", indicating that the boron-containing MTQ silicone resin alone was not sufficient to provide sufficient adhesion.

[0119] In Comparative Example 3, the silicone pressure-sensitive adhesive, the amount of reaction product B was insufficient (200 parts), resulting in most of the test results showing "interface failure", and only the silicone rubber with lower hardness (20A) reached "cohesive failure".

[0120] Therefore, it can be seen that interface destruction occurs when the synthesized additive B is not added; interface destruction also occurs when an insufficient amount of the reaction product B is added.

[0121] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A silicone pressure-sensitive adhesive for bonding silicone rubber, characterized in that: The invention comprises the following raw materials in parts by weight: 300 parts of vinyl-terminated polydimethylsiloxane, 300-500 parts of the reaction product B of hydroxyl-terminated polydimethylsiloxane and boron-containing MTQ silicone resin, 3 parts of a crosslinking agent, 450 parts of an MQ silicone resin, 2 parts of an inhibitor, 8 parts of a catalyst, and 1500 parts of a solvent; The hydroxyl-terminated polydimethylsiloxane has a molecular weight of 300,000 to 600,000; The boron-containing MTQ silicone resin has a number average molecular weight Mn of 2000-20000 g / mol; the boron-containing MTQ silicone resin is a reaction product B of borate ester, ethyl orthosilicate and hexamethyldisiloxane; the borate ester is any one of triethyl borate, tripropyl borate and tributyl borate.

2. The organic silicone pressure-sensitive adhesive according to claim 1, characterized in that: The vinyl-terminated polydimethylsiloxane has a molecular weight of 600,000 to 800,000.

3. The organic silicone pressure-sensitive adhesive according to claim 1, characterized in that: In the boron-containing MTQ silicone resin, the molar ratio of M / T / Q is 0.8 / 0.5 / 1.0 to 0.8 / 1.0 / 1.

0.

4. The organic silicone pressure-sensitive adhesive according to claim 1, characterized in that: The crosslinking agent is polydimethylsiloxane with a hydrogen mass fraction of 1.6%.

5. The organic silicone pressure-sensitive adhesive according to claim 1, characterized in that: In the MQ silicone resin, the M / Q ratio is 0.7-0.8, and the number average molecular weight is 3000-5000 g / mol.

6. The organic silicone pressure-sensitive adhesive according to claim 1, characterized in that: The inhibitor is ethynyl cyclohexanol.

7. The organic silicone pressure-sensitive adhesive according to claim 1, characterized in that: The catalyst is a platinum catalyst, and the content of platinum in the platinum catalyst is 5000ppm.

8. The organic silicone pressure-sensitive adhesive according to claim 1, characterized in that: The solvent is any one or more of toluene, xylene, ethyl acetate and butyl acetate.

9. The method for preparing the organosilicon pressure-sensitive adhesive according to any one of claims 1 to 8, characterized in that: The following steps are involved: In a reactor, 300 parts of vinyl-terminated polydimethylsiloxane, 300-500 parts of a reaction product B of hydroxyl-terminated polydimethylsiloxane and boron-containing MTQ silicone resin, 3 parts of a crosslinking agent, 450 parts of MQ silicone resin, 2 parts of an inhibitor, 8 parts of a platinum catalyst, and 1500 parts of a solvent are added; the mixture is mixed at room temperature to obtain a silicone pressure-sensitive adhesive.

10. Application of silicone pressure-sensitive adhesive, characterized in that: The organic silicone pressure-sensitive adhesive according to any one of claims 1 to 8 or the organic silicone pressure-sensitive adhesive prepared by the preparation method according to claim 9 is coated on a substrate, and after being cured, is bonded to the silicone rubber.

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