Addition type liquid silicone rubber tackifier as well as preparation method and application thereof

Abstract

The invention provides an addition type liquid silicone rubber tackifier as well as a preparation method and application thereof. The addition type liquid silicone rubber tackifier is prepared by reacting organic hydrogenated polysiloxane with an acrylic acid compound containing an epoxy group and an ester group under the action of a platinum catalyst, wherein the organic hydrogenated polysiloxane is polysiloxane containing at least two or more hydrogen atoms directly connected with Si atoms, all the hydrogen atoms are located at chain ends and directly connected with the Si atoms, or the chain ends and side chains contain the hydrogen atoms directly connected with the Si atoms at the same time. The tackifier synthesized by the invention can obviously improve the bonding performance of the addition type liquid silicone rubber and an adherend, and the bonding failure between the formed liquid silicone rubber and engineering plastics can reach 100% cohesive failure by adding a small amount of tackifier into the formed liquid silicone rubber; especially, the problem of the bonding effect between the molded liquid silicone rubber and PC can be solved, and 100% cohesive failure can also be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to an addition-type liquid silicone rubber tackifier and a preparation method and application thereof. Background Art

[0002] With the development of science and technology, addition-type liquid silicone rubber has been widely used in the fields of aviation, automobile, construction, medical treatment, electronics, etc. due to its excellent moisture resistance, high and low temperature resistance, UV resistance, electrical insulation, radiation resistance and ozone resistance. Its main applications include: LED potting glue, liquid injection potting glue and mold glue. However, since the molecular chain segment of dimethyl silicone rubber in liquid silicone rubber is a coiled helical structure, and the non-polar methyl side chain will also cause the polarity of the Si-O-Si bond to be shielded, the entire silicone rubber molecule is a non-polar structure. On the other hand, due to the very weak activity of the methyl side group, dimethyl silicone rubber has poor adhesion to general substrates, such as plastics, metals, cloth and glass fiber, which seriously limits its further application. Therefore, it is of great practical significance to modify the addition-type liquid silicone rubber and give it excellent bonding properties.

[0003] In the prior art, the optimization of the bonding performance of addition-type silicone rubber mainly includes the following three directions: (1) surface treatment of the adherend, such as corona discharge, plasma, primer, etc.; however, the storage performance of the primer in this method is poor, and a large amount of organic solvent will volatilize during use, which poses a safety hazard, which limits its further application; (2) modification of polysiloxane, introducing active groups such as epoxy, isocyanate and acrylate groups into vinyl polymers or hydrogen-containing crosslinking agents; however, this method is complex and difficult to control in the process of modifying the basic polysiloxane constituting silicone rubber. There are many side reactions, which leads to an increase in production costs and greatly limits its further promotion and application; (3) by adding a tackifier. In this method, the tackifier can be an oligosiloxane containing active groups such as carbonyl, epoxy, alkoxy, ester, and hydroxyl groups that can react with silicone rubber and the surface of the adherend at the same time. Only a small amount of tackifier needs to be added to the basic polysiloxane to make it self-adhesive. After vulcanization, it can achieve good adhesion with the adherend. This method is not only simple to operate and the process is easy to control, but also the bonding performance of silicone rubber can be greatly improved, which has a very good application prospect. For example, Chinese invention patent CN108239284A discloses an addition-type liquid silicone rubber tackifier and a preparation method thereof. The tackifier is obtained by using dimethyldialkoxysilane, diphenyldialkoxysilane, methylvinyldialkoxysilane, γ-glycidyloxypropyltrialkoxysilane, and γ-(methacryloyloxy)propyltrialkoxysilane as raw materials, and undergoing hydrolysis reaction and equilibrium reaction. The obtained tackifier contains epoxy groups and vinyl groups. However, the reaction conditions of this method are harsh and need to be carried out under high temperature and reduced pressure conditions. Many types of reaction raw materials are added, which brings many inconveniences to actual production. In addition, the reaction energy consumption is high and the complexity of process control limits its large-scale application and promotion.

[0004] Furthermore, in the prior art, for example, Chinese invention patent CN103360422A discloses the synthesis of an organosilicon tackifier using tetramethylcyclotetrasiloxane and 1,6-hexanediol diacrylate. By adding the tackifier to addition-type liquid silicone rubber, the bonding performance of silicone rubber to aromatic polycarbonate can be improved, but its bonding failure to PC is only 40% to 60% cohesive failure, and cannot reach 100% cohesive failure. Chinese invention patent CN102675884A discloses the synthesis of an organosilicon tackifier using allyl glycidyl ether and phenyl-containing hydrogenated silicone oil. By adding the tackifier to addition-type liquid silicone rubber, the bonding with silicone rubber and plastic can be achieved, but the high cost of the synthetic raw materials also limits its further use.

[0005] Based on the above problems, there is an urgent need to provide an addition-type liquid silicone rubber tackifier that has a simple and easy-to-control process and can achieve 100% cohesive failure. Summary of the invention

[0006] In view of the technical problems existing in the prior art, the present invention provides an addition-type liquid silicone rubber tackifier and a preparation method and application thereof.

[0007] The first object of the present invention is to provide a method for preparing an addition-type liquid silicone rubber tackifier, wherein the addition-type liquid silicone rubber tackifier is prepared by reacting an organic hydrogenated polysiloxane with an acrylic compound containing an epoxy group and an ester group under the action of a platinum catalyst;

[0008] The addition type liquid silicone rubber tackifier has a general structural formula shown in formula (1) or formula (2):

[0009]

[0010]

[0011] Wherein, m, n, and i are all integers of 0 to 100, and the sum of m, n, and i is an integer of 1 to 300.

[0012] R1, R2, R3 and R4 are H; or, any one of formula (3), formula (4) and formula (5), and at least one of R1, R2, R3 and R4 is H; the structural formulas of formula (3), formula (4) and formula (5) are respectively:

[0013]

[0014] The organohydrogenated polysiloxane is a polysiloxane containing at least two or more hydrogen atoms directly connected to Si atoms, wherein all the hydrogen atoms are located at the chain ends and directly connected to Si atoms, or both the chain ends and the side chains contain hydrogen atoms directly connected to Si atoms.

[0015] Preferably, the hydrogen content of the organic hydrogen-containing polysiloxane is 0.1-2%.

[0016] Preferably, the content of vinyl groups in the acrylic compound containing epoxy groups and ester groups is 10 wt % to 30 wt %.

[0017] Preferably, the organic hydrogen-containing polysiloxane is any one of tetramethyltetrahydrocyclotetrasiloxane and linear organic polysiloxane.

[0018] Preferably, the acrylic compound containing epoxy group and ester group is any one of glycidyl acrylate, glycidyl methacrylate and 4-hydroxybutyl acrylate glycidyl ether.

[0019] Preferably, the platinum catalyst is chloroplatinic acid or platinum (0)-1,3,5,7-tetravinyl-1,3,5,7-tetramethyl-cyclotetrasiloxane complex solution.

[0020] Specifically, the present invention also provides a method for preparing the above-mentioned addition-type liquid silicone rubber tackifier, comprising the following steps:

[0021] S1. The acrylic compound containing epoxy group and ester group is mixed with the platinum catalyst solution and then preheated to obtain a first mixed solution, wherein the platinum catalyst is coordinated with the vinyl group to increase the reactivity of the vinyl group;

[0022] S2. The organohydrogen polysiloxane and the polymerization inhibitor are added to the solvent and refluxed, heated to reflux, and stirred to obtain a second mixed solution;

[0023] S3. Slowly adding the first mixed solution dropwise to the second mixed solution, controlling the temperature at 60-100°C, reacting for 0.5-3h, and causing the vinyl groups in the first mixed solution to undergo a hydrosilylation reaction with the hydrogen-containing groups in the second mixed solution to obtain a reaction solution;

[0024] S4. After the reaction solution is cooled to room temperature, an adsorbent is added to remove the platinum catalyst, and finally the addition-type liquid silicone rubber tackifier is obtained by rotary evaporation under reduced pressure.

[0025] Preferably, in S1, the preheating includes keeping warm at 30-80°C for 30-60 minutes.

[0026] Preferably, in S2, the heating reflux temperature is 40 to 90° C., and the time is 1 to 1.5 h.

[0027] Preferably, the polymerization inhibitor is 4-hydroxyanisole.

[0028] Preferably, in S3, the speed at which the first mixed solution is added dropwise to the second mixed solution is 0.5-1 g / min.

[0029] Preferably, the adsorbent is activated carbon; preferably, the activated carbon is selected from one or more of coconut shell activated carbon particles, rice husk activated carbon particles, and coal particles.

[0030] Preferably, the platinum catalyst solution is an isopropanol solution of chloroplatinic acid or a platinum (0)-1,3,5,7-tetravinyl-1,3,5,7-tetramethyl-cyclotetrasiloxane complex solution, and the concentration of the platinum catalyst solution is 0.05-0.5 wt %.

[0031] Preferably, the addition amount of the platinum catalyst solution and the acrylic compound containing epoxy groups and ester groups is prepared as (0.005-0.05): (80-120).

[0032] Preferably, the molar ratio of Si—H of the organohydrogenpolysiloxane to the vinyl group of the acrylic compound containing epoxy group and ester group is 1:(1-5).

[0033] Preferably, the added mass ratio of the organohydrogenpolysiloxane, the organic solvent and the polymerization inhibitor is (100-150):(100-200):(0.1-1).

[0034] As another object of the present invention, an addition type liquid silicone rubber is provided, which at least comprises the above-mentioned addition type liquid silicone rubber tackifier; the addition amount of the addition type liquid silicone rubber tackifier is 0.4-4wt%.

[0035] Preferably, the preparation method of the addition type liquid silicone rubber comprises: mixing vinyl-terminated polydimethylsiloxane and methyl hydrogen polysiloxane, adding the addition type liquid silicone rubber tackifier, inhibitor, and platinum catalyst, stirring and mixing evenly, and performing vulcanization reaction to obtain the addition type liquid silicone rubber.

[0036] Preferably, the inhibitor is ethynyl cyclohexanol; the platinum catalyst is an isopropanol solution of chloroplatinic acid or a platinum (0)-1,3,5,7-tetravinyl-1,3,5,7-tetramethyl-cyclotetrasiloxane complex solution; the vinyl content in the vinyl-terminated polydimethylsiloxane is 0.1 to 0.5 mol%; the hydrogen content in the methyl hydrogen polysiloxane is preferably 0.3wt% to 1.5wt% of the hydrogen content of the hydrogen-containing silicone oil.

[0037] The addition type liquid silicone rubber provided by the present invention acts as a bonding agent between engineering plastics and metal materials; the engineering plastics include any one of PC, PA, PET, PI, and PP; the metal material includes any one of copper sheets, stainless steel sheets, and aluminum sheets.

[0038] The technical effects of the technical solution of the present invention are as follows:

[0039] 1. The tackifier synthesized in the present invention can significantly improve the bonding performance between the addition-type liquid silicone rubber and the adherend. By adding a small amount of tackifier to the molded liquid silicone rubber, the bonding failure between the molded liquid silicone rubber and the engineering plastic can reach 100% cohesive failure, especially the bonding effect between the molded liquid silicone rubber and PC can also achieve 100% cohesive failure.

[0040] 2. The thickener synthesized by the technical solution of the present invention is very friendly to the platinum catalyst and will not cause the catalyst to be poisoned and ineffective. It can be recycled and reused repeatedly by adsorption, and will not cause the catalytic efficiency to be reduced, thereby reducing the catalyst cost. Moreover, the raw materials used in the present invention do not require additional synthesis steps and can be directly purchased. The cost of the raw materials is low, which can greatly reduce the production cost.

[0041] 3. The technical solution of the present invention has a simple process, is easy to control during the manufacturing process, and is suitable for large-scale industrial production.

[0042] 4. The present invention can be used for bonding addition-type liquid silicone rubber to various engineering plastic materials such as PC, PA, PET, PI, PP, and metals such as copper sheets, stainless steel sheets, and aluminum sheets, and particularly solves the bonding problem in the prior art that the bonding failure of the adhesive to the PC material is only 40% to 60% cohesive failure and cannot reach 100% cohesive failure. DETAILED DESCRIPTION

[0043] To make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention is clearly and completely described. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0044] To achieve the above-mentioned purpose, the present invention provides an addition-type liquid silicone rubber tackifier, the structural formula of which is shown in Formula (1) or Formula (2).

[0045] The cohesive failure of the adhesive occurs within the adhesive layer. This form of failure indicates that the adhesive itself has sufficient cohesive strength to resist external forces, thereby maintaining a firm bond between the adhered objects. When bonding materials, 100% cohesive failure means that the adhesive can fully exert its bonding properties, achieve the maximum bonding strength, and ensure the reliability and durability of the bonding. The present invention shows 100% cohesive failure in the bonding of PC, PET, and aluminum sheets, indicating that the tackifier significantly reduces the internal stress caused by the difference in performance between the adhesive and the material when curing. For example, when R1, R2, R3 and R4 in formula (1) or formula (2) are independently one of formula (3), formula (4) and formula (5) (at least one of the substituents is H), the mechanical strength and rigidity of the tackifier material are enhanced due to the introduction of the epoxy structure in the structural formula, thereby reducing the performance difference between the tackifier and materials such as PC, PET, and aluminum sheets; in particular, the cyclic silicon oxide structure of formula (2) can also show strong rigidity even when R1, R2, R3 and R4 are all H. Therefore, the present invention reduces the performance difference between the tackifier and PC, PET, and aluminum sheets by controlling the number of substituents and repeating units in the structural formula, thereby minimizing the internal stress caused by the above differences, thereby enhancing the bonding performance of the tackifier and having 100% cohesive failure.

[0046] The structural formulas of formula (1) to formula (2) are respectively:

[0047]

[0048] Wherein, m, n, and i are all integers of 0 to 100, and the sum of m, n, and i is an integer of 1 to 300;

[0049] R1, R2, R3 and R4 are each independently H; or, R1, R2, R3 and R4 are each independently any one of the structures represented by formula (3), formula (4) and formula (5), and at least one of R1, R2, R3 and R4 is H.

[0050] The structural formulas of formula (3), formula (4) and formula (5) are as follows:

[0051]

[0052] The present invention also provides a method for preparing an addition-type liquid silicone rubber tackifier, wherein the reaction raw materials are reacted according to the following mass proportions: 80 to 120 parts of an acrylic compound containing epoxy groups and ester groups, 0.005 to 0.05 parts of a platinum catalyst solution, 100 to 150 parts of an organohydrogenated polysiloxane, 100 to 200 parts of a reaction solvent, and 0.1 to 1 part of an inhibitor.

[0053] In a specific embodiment of the present invention, the polymerization inhibitor is preferably 4-hydroxyanisole.

[0054] In a specific embodiment of the present invention, the reaction solvent is preferably toluene.

[0055] As a preferred embodiment, the preparation method comprises the following steps:

[0056] Step 1: 80-120 parts of an acrylic compound containing epoxy groups and ester groups are mixed with 0.005-0.05 parts of a platinum catalyst solution having a mass concentration of 0.05-0.5%, and preheated at 30-80° C. for 30-60 minutes to form a mixed solution for standby use;

[0057] Step 2: Add 100-150 parts of organohydrogen polysiloxane, 100-200 parts of toluene and 0.1-1 parts of 4-hydroxyanisole into a round-bottom flask equipped with a reflux condenser, a thermometer and a dropping funnel, and heat to 40-90°C while stirring. Slowly drop the mixed solution in the first step into the round-bottom flask within 1-2 hours. After the dropwise addition is completed, control the temperature at 60-100°C and react for 0.5-3 hours;

[0058] Step 3: After the reaction liquid is cooled to room temperature, 20 to 50 parts of activated carbon are added to adsorb the residual platinum catalyst, the reaction liquid is filtered to remove the activated carbon and the adsorbed platinum catalyst, and finally the viscosity enhancer is obtained by reduced pressure rotary evaporation.

[0059] The molar ratio of Si-H of the organohydrogen polysiloxane to the vinyl group of the acrylic compound containing epoxy group and ester group is 1:1 to 5:1.

[0060] The organohydrogenated polysiloxane is a polysiloxane containing at least two hydrogen atoms directly connected to Si, wherein the hydrogen atoms are located at the chain ends, or the chain ends and side chains contain hydrogen atoms directly connected to Si;

[0061] Preferably, the hydrogen content of the hydrogen-containing polysiloxane is 0.1-2%.

[0062] More preferably, the hydrogen-containing polysiloxane is any one of tetramethyltetrahydrocyclotetrasiloxane and linear organopolysiloxane.

[0063] The acrylic compound containing epoxy group and ester group is any one of glycidyl acrylate, glycidyl methacrylate and 4-hydroxybutyl acrylate glycidyl ether.

[0064] The platinum catalyst is any one of an isopropanol solution of chloroplatinic acid and a platinum (0)-1,3,5,7-tetravinyl-1,3,5,7-tetramethyl-cyclotetrasiloxane complex solution.

[0065] The activated carbon is one or more of coconut shell activated carbon particles, rice husk activated carbon particles, and coal particles.

[0066] The tackifier prepared by the above technical solution is added to the addition type liquid silicone rubber, and the added amount is 0.5-4% of the weight of the addition type liquid silicone rubber.

[0067] The technical solution of the present invention is further described in detail below through specific embodiments.

[0068] Example 1

[0069] This embodiment provides a method for preparing an addition-type liquid silicone rubber tackifier, and the specific steps include: mixing 60g of glycidyl acrylate and 0.1g of isopropanol solution (0.4wt%) of chloroplatinic acid to form a first mixed solution, and preheating it at 50°C for 50min for standby use.

[0070] 75 g of tetramethyltetrahydrocyclotetrasiloxane, 90 g of toluene and 0.3 g of 4-hydroxyanisole were added into a round-bottom flask equipped with a reflux condenser, a thermometer and a dropping funnel, and the mixture was heated to 70° C. for preheating for 1 h under nitrogen protection to obtain a second mixed solution.

[0071] The preheated first mixed solution containing glycidyl acrylate and isopropanol solution of chloroplatinic acid is slowly added dropwise to the round-bottom flask at a dropping speed of 0.5 to 1 g / min. After the dropping is completed, the temperature is controlled at 80° C. and the reaction is carried out for 2 hours to obtain a reaction solution.

[0072] After the reaction liquid was cooled to room temperature, 20 g of coconut shell activated carbon particles were added to adsorb the residual platinum catalyst, the reaction liquid was filtered to remove the activated carbon and the adsorbed platinum catalyst, and finally the organic silicon thickener was obtained by reduced pressure rotary evaporation.

[0073] The obtained organosilicon tackifier is a mixture having a general structure as shown in formula (2), wherein in formula (2), R1, R2, R3 and R4 are independently the structure shown in formula (3) or H, and the molar ratio of the structure shown in formula (3) to H is 1:1.7, and the average molecular weight of the mixture is 431.

[0074] Furthermore, this embodiment also provides a method for preparing an addition-type silicone rubber using the above-mentioned silicone thickener, comprising: mixing 100 g of vinyl-terminated polydimethylsiloxane (vinyl content 0.15 mmol / g) with 5 g of methyl hydrogen polysiloxane (hydrogen content 5.5 mmol / g), then adding 1 g of the silicone thickener prepared by the above method, 0.1 g of ethynyl cyclohexanol, and 0.2 g of an isopropanol solution of chloroplatinic acid, stirring and mixing evenly, and vulcanizing at 120° C. for 5 min to obtain the addition-type silicone rubber of this embodiment, which is recorded as S1.

[0075] The properties of the samples are shown in Table 1.

[0076] Example 2

[0077] This embodiment provides a method for preparing an addition-type liquid silicone rubber tackifier, and the specific steps include:

[0078] 66 g of glycidyl methacrylate and 0.1 g of an isopropanol solution of chloroplatinic acid (0.4 wt %) were mixed evenly, and preheated at 50° C. for 50 min to obtain a first mixed solution for standby use.

[0079] 75 g of tetramethyltetrahydrocyclotetrasiloxane, 90 g of toluene and 0.3 g of 4-hydroxyanisole were added into a round-bottom flask equipped with a reflux condenser, a thermometer and a dropping funnel, and the mixture was heated to 70° C. for preheating for 1 h under nitrogen protection to obtain a second mixed solution.

[0080] The preheated first mixed solution was slowly added dropwise to the second mixed solution in the round-bottom flask at a dropping speed of 0.5-1 g / min. After the addition was completed, the temperature was controlled at 80° C. and the reaction was carried out for 2 hours to obtain a reaction solution.

[0081] After the reaction solution was cooled to room temperature, 20 g of coconut shell activated carbon particles were added to adsorb the residual platinum catalyst, the reaction solution was filtered to remove the activated carbon and the adsorbed platinum catalyst, and finally the organosilicon thickener was obtained by reduced pressure rotary evaporation.

[0082] The obtained organosilicon tackifier is a mixture having a general structure as shown in formula (2), wherein R1, R2, R3 and R4 are independently the structural formula shown in formula (4) or H, and the molar ratio of the structural formula shown in formula (4) to H is 1:1.7, and the average molecular weight of the mixture is 455.

[0083] Furthermore, this embodiment also provides a method for preparing an addition-type silicone rubber using the above-mentioned silicone thickener, comprising: mixing 100 g of vinyl-terminated polydimethylsiloxane (vinyl content 0.15 mmol / g) with 5 g of methyl hydrogen polysiloxane (hydrogen content 5.5 mmol / g), then adding 1 g of the silicone thickener prepared by the above method, 0.1 g of ethynyl cyclohexanol, and 0.2 g of isopropanol solution of chloroplatinic acid, stirring and mixing evenly, and vulcanizing at 120°C for 5 min to obtain the addition-type silicone rubber of this embodiment, recorded as S2.

[0084] The properties of the samples are shown in Table 1.

[0085] Example 3

[0086] This embodiment provides a method for preparing an addition-type liquid silicone rubber tackifier, and the specific steps include:

[0087] 94 g of 4-hydroxybutyl acrylate glycidyl ether and 0.1 g of an isopropanol solution of chloroplatinic acid (0.4 wt %) were mixed evenly, and preheated at 50° C. for 50 min to obtain a first mixed solution for standby use.

[0088] 75 g of tetramethyltetrahydrocyclotetrasiloxane, 90 g of toluene and 0.3 g of 4-hydroxyanisole were added into a round-bottom flask equipped with a reflux condenser, a thermometer and a dropping funnel, and the mixture was heated to 70° C. for preheating for 1 h under nitrogen protection to obtain a second mixed solution.

[0089] The preheated first mixed solution was slowly dripped into the round-bottom flask at a dripping speed of 0.5-1 g / min. After the dripping was completed, the temperature was controlled at 80° C. and the reaction was carried out for 2 hours to obtain a reaction solution.

[0090] After the reaction solution was cooled to room temperature, 20 g of coconut shell activated carbon particles were added to adsorb the residual platinum catalyst, the reaction solution was filtered to remove the activated carbon and the adsorbed platinum catalyst, and finally the organosilicon thickener was obtained by reduced pressure rotary evaporation.

[0091] The obtained organosilicon tackifier is a mixture having a general structure as shown in formula (2), wherein R1, R2, R3 and R4 are independently the structural formula shown in formula (5) or H, and the molar ratio of the structural formula shown in formula (5) to H is 1:1.7, and the average molecular weight of the mixture is 542.

[0092] Furthermore, this embodiment also provides a method for preparing an addition-type silicone rubber using the above-mentioned organosilicon thickener, comprising: mixing 100 g of vinyl-terminated polydimethylsiloxane (vinyl content 0.15 mmol / g) with 5 g of methyl hydrogen polysiloxane (hydrogen content 5.5 mmol / g), then adding 1 g of thickener 1, 0.1 g of ethynyl cyclohexanol, and 0.2 g of isopropanol solution of chloroplatinic acid, stirring and mixing evenly, and vulcanizing at 120° C. for 5 min to obtain an addition-type silicone rubber, recorded as S3.

[0093] The properties of the samples are shown in Table 1.

[0094] Comparative Example 1

[0095] 100g of vinyl-terminated polydimethylsiloxane (vinyl content 0.15mmol / g) was mixed with 5g of methylhydrogenpolysiloxane (hydrogen content 5.5mmol / g), and then 0.1g of ethynylcyclohexanol and 0.2g of isopropanol solution of chloroplatinic acid were added, stirred and mixed evenly, and vulcanized at 120℃ for 5min to form. The addition-type silicone rubber composition of this embodiment was obtained, which was recorded as C1. The properties of the samples are shown in Table 1. It can be seen from Table 1 that the bonding failure mode of the addition-type liquid silicone rubber C1 with PC, PET and aluminum sheet is 100% interface failure, which shows that the bonding performance of the addition-type liquid silicone rubber without adding a tackifier is very poor.

[0096] Adhesion performance test:

[0097] Use the tensile shear test to test standard specifications of PC, PET, and aluminum sheets. Take two sheets of each sheet, clean them, apply silicone rubber on the front end of the two substrates, and then bake them at 120 degrees for 10 minutes to bond the silicone rubber to the substrate, and then test the bonding performance of the silicone rubber.

[0098] Table 1 is the bonding performance test of addition type liquid silicone rubber

[0099] PC bonding situation PET bonding Aluminum sheet bonding Example 1 100% cohesive failure 100% cohesive failure 100% cohesive failure Example 2 100% cohesive failure 100% cohesive failure 100% cohesive failure Example 3 100% cohesive failure 100% cohesive failure 100% cohesive failure Comparative Example 1 100% interface damage 100% interface damage 100% interface damage

[0100] As can be seen from Table 1, compared with Comparative Example 1, the adhesion of Examples 1-3 to PC, PET and aluminum sheets has been significantly improved, and the adhesive failure has reached 100% cohesive failure. This is because the ester group and epoxy group in the tackifier react chemically with the surface of the substrate to form a strong chemical bond, achieving a strong bond between the addition-type liquid silicone rubber and the substrate. Secondly, the silicon-hydrogen bond in the tackifier can participate in the cross-linking reaction of the silicone rubber and can also improve the mechanical properties of the silicone rubber.

[0101] The above are only preferred embodiments of the present invention, which do not limit the protection scope of the present invention. For those skilled in the art, the present invention may have various modifications and changes. Within the spirit and principle of the present invention, changes, modifications, replacements, integrations and parameter changes to these embodiments by conventional substitutions or by being able to achieve the same functions without departing from the principles and spirit of the present invention all fall within the protection scope of the present invention.

Claims

1. A method for preparing an addition-type liquid silicone rubber tackifier, characterized in that: The addition type liquid silicone rubber tackifier is prepared by reacting an organic hydrogenated polysiloxane with an acrylic compound containing epoxy groups and ester groups under the action of a platinum catalyst; Wherein, the addition type liquid silicone rubber tackifier has a general structural formula shown in formula (1) or formula (2): Wherein, m, n, and i are all integers of 0 to 100, and the sum of m, n, and i is an integer of 1 to 300; R1, R2, R3 and R4 are each independently H; or, R1, R2, R3 and R4 are each independently any one of the structures shown in formula (3), formula (4) and formula (5), and at least one of R1, R2, R3 and R4 is H; the structural formulas of formula (3), formula (4) and formula (5) are respectively: The organohydrogenated polysiloxane is a polysiloxane containing at least 2 or more hydrogen atoms directly connected to Si atoms, wherein all hydrogen atoms are located at the chain ends and directly connected to Si atoms, or both the chain ends and the side chains contain hydrogen atoms directly connected to Si atoms.

2. The method for preparing the addition type liquid silicone rubber tackifier according to claim 1, characterized in that: The hydrogen content of the organic hydrogen-containing polysiloxane is 0.1 to 2%; The content of the vinyl group in the acrylic compound containing an epoxy group or an ester group is 10 wt % to 30 wt %.

3. The method for preparing the addition type liquid silicone rubber tackifier according to claim 1, characterized in that: The organic hydrogen-containing polysiloxane is any one of tetramethyltetrahydrocyclotetrasiloxane and linear organic polysiloxane; And / or, the acrylic compound containing epoxy group and ester group is any one of glycidyl acrylate, glycidyl methacrylate and 4-hydroxybutyl acrylate glycidyl ether; And / or, the platinum catalyst is chloroplatinic acid or platinum (0)-1,3,5,7-tetravinyl-1,3,5,7-tetramethyl-cyclotetrasiloxane complex solution.

4. The method for preparing the addition type liquid silicone rubber tackifier according to claim 1, characterized in that: The specific steps include: S1. The acrylic compound containing epoxy group and ester group is mixed with the platinum catalyst solution and then preheated to obtain a first mixed solution, wherein the platinum catalyst coordinates with the vinyl group, which is beneficial to improve the reaction activity of the vinyl group; S2. The organohydrogen polysiloxane and the polymerization inhibitor are added to the solvent and refluxed, heated to reflux, and stirred to obtain a second mixed solution; S3. slowly adding the first mixed solution dropwise to the second mixed solution, controlling the temperature at 60-100°C, reacting for 0.5 to 3h, and causing the vinyl groups in the first mixed solution to undergo a hydrosilylation reaction with the hydrogen-containing groups in the second mixed solution to obtain a reaction solution; S4. After the reaction solution is cooled to room temperature, an adsorbent is added to remove the platinum catalyst, and finally the addition-type liquid silicone rubber tackifier is obtained by rotary evaporation under reduced pressure.

5. The method for preparing the addition type liquid silicone rubber tackifier according to claim 4, characterized in that: In S1, the preheating includes keeping the temperature at 30 to 80° C. for 30 to 60 minutes; And / or, in S2, the heating reflux temperature is 40 to 90° C., and the time is 0.5 to 3 h; The inhibitor is 4-hydroxyanisole; and / or, in S3, the speed at which the first mixed solution is added dropwise to the second mixed solution is 0.5 to 1 g / min; And / or, the adsorbent is activated carbon; preferably, the activated carbon is selected from one or more of coconut shell activated carbon particles, rice husk activated carbon particles, and coal particles.

6. The method for preparing the addition type liquid silicone rubber tackifier according to claim 4, characterized in that: The platinum catalyst solution is an isopropanol solution of chloroplatinic acid or a platinum (0)-1,3,5,7-tetravinyl-1,3,5,7-tetramethyl-cyclotetrasiloxane complex solution, and the concentration of the platinum catalyst solution is 0.05-0.5wt%; The addition amount of the platinum catalyst solution and the acrylic compound containing epoxy group and ester group is prepared as (0.005-0.05): (80-120); The molar ratio of Si-H of the organohydrogen polysiloxane to the vinyl of the acrylic compound containing epoxy group and ester group is 1:(1-5); The added mass ratio of the organohydrogenpolysiloxane, the organic solvent and the polymerization inhibitor is (100-150):(100-200):(0.1-1).

7. An addition type liquid silicone rubber, comprising at least the addition type liquid silicone rubber tackifier according to claim 6 or 7; The addition amount of the addition type liquid silicone rubber tackifier is 0.4-4wt%.

8. The addition type liquid silicone rubber according to claim 7, characterized in that: The preparation method of the addition type liquid silicone rubber comprises: mixing vinyl-terminated polydimethylsiloxane and methyl hydrogen polysiloxane, adding the addition type liquid silicone rubber tackifier, inhibitor and platinum catalyst, stirring and mixing evenly, and performing vulcanization reaction to obtain the addition type liquid silicone rubber.

9. The addition type liquid silicone rubber according to claim 7, characterized in that: The inhibitor is ethynyl cyclohexanol; the platinum catalyst is an isopropanol solution of chloroplatinic acid or a platinum (0)-1,3,5,7-tetravinyl-1,3,5,7-tetramethyl-cyclotetrasiloxane complex solution; the vinyl content in the vinyl-terminated polydimethylsiloxane is 0.1 to 0.5 mol%; the hydrogen content in the methyl hydrogen polysiloxane is preferably 0.3 wt% to 1.5 wt% of the hydrogen content of the hydrogen-containing silicone oil.

10. The addition type liquid silicone rubber as described in any one of claims 7 to 9 acts as a bonding agent in bonding engineering plastics and metal materials; the engineering plastics include any one of PC, PA, PET, PI, and PP; the metal material includes any one of copper sheets, stainless steel sheets, and aluminum sheets.

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