A tackifier for peroxide-cured silicone pressure-sensitive adhesive and its application

Abstract

This invention belongs to the field of adhesive technology and relates to a tackifier for peroxide-cured silicone pressure-sensitive adhesives. The tackifier is derived from the addition of a terminal or side organohydrogen polysiloxane to a (meth)acrylic monomer. It contains no residual silicon hydrogen groups but retains some silylmethyl groups or vinyl groups from the (meth)acrylic monomer. It can be used in peroxide-cured silicone pressure-sensitive adhesives to enhance their release strength from substrates.

Description

Technical Field

[0001] The invention belongs to the technical field of tackifiers, and particularly relates to a tackifier for peroxide-cured silicone pressure-sensitive adhesive and application thereof. Background Art

[0002] Silicone pressure-sensitive adhesives generally refer to those based on silicone polymers. Compared to acrylic pressure-sensitive adhesives, silicone pressure-sensitive adhesives offer superior heat resistance, weather resistance, and insulation performance. Based on their curing mechanisms, they are primarily marketed as hydrosilylation-based and peroxide-cured. Peroxide-cured adhesives are favored by the market because they can adjust the degree of crosslinking simply by adjusting the catalyst dosage, resulting in varying physical properties.

[0003] Because silicone pressure-sensitive adhesive is mainly composed of non-polar organic groups and has low surface energy, its adhesion to most substrates is still far behind that of traditional acrylic pressure-sensitive adhesives. Therefore, how to improve its adhesion to the adhered substrates has always been a research hotspot for practitioners.

[0004] Numerous reports have been published on tackifiers for use in silicone materials. A typical approach involves adding a linear or cyclic SiH-containing organosilicon to a vinyl-containing acrylic monomer, leaving a residual SiH bond. These tackifiers are then applied to addition-type silicones to achieve adhesion to various substrates, as described in patents such as US8916646B2 and CN102276989A. However, due to the residual SiH bonds and the difficulty in removing the catalyst required for the hydrosilation reaction, these tackifiers are unstable upon storage, prone to viscosity growth and even crosslinking. In peroxide-cured silicone pressure-sensitive adhesives, SiH bonds are not required for the subsequent crosslinking reaction, and no hydrosilation-synthesized tackifiers have been reported for this application. Summary of the Invention

[0005] The purpose of the present invention is to provide a tackifier for peroxide-cured silicone pressure-sensitive adhesive and its application. The tackifier is synthesized by hydrogen silicification method and can be applied to peroxide-cured silicone pressure-sensitive adhesive to enhance its peeling force on the substrate to be attached.

[0006] The present invention is achieved by the following technical solution: A tackifier for peroxide-curable silicone pressure-sensitive adhesive, the structural formula of which is as follows:

[0007] ;

[0008] Among them, R1, R3, and R5 are "or" "" "" "One or more of;

[0009] R2 and R4 are structural groups formed by the reaction of a monofunctional (meth)acrylic acid monomer with hydrosilylation, and the corresponding monomers are one or more of acrylic acid, allyl glycidyl ether, hydroxyethyl (meth)acrylate, hydroxybutyl (meth)acrylate, 3,3,5-trimethylcyclohexane acrylate, and tetrahydrofuran (meth)acrylate;

[0010] R6 and R7 are structural groups formed by the reaction of methyl or difunctional and trifunctional (meth) acrylic monomers with hydrosilylation, and the corresponding monomers are one or more of ethylene glycol dimethacrylate, ethoxylated bisphenol A dimethacrylate, diallyl terephthalate, cyclohexanedimethanol diacrylate, trimethylolpropane trimethacrylate, and triallyl isocyanurate.

[0011] The present invention provides application of a tackifier in a peroxide-cured organic silicon pressure-sensitive adhesive.

[0012] The invention provides a peroxide-cured organic silicon pressure-sensitive adhesive, comprising 80-120 parts by mass of 107 glue, 30-70 parts by mass of MQ silicone resin, 200-250 parts by mass of toluene, 10-15 parts by mass of benzoyl peroxide and a tackifier, wherein the tackifier accounts for 0.5-5% by weight of the total mass.

[0013] The tackifier of this invention is derived from the addition of end- or end-organohydrogen polysiloxane to a (meth)acrylic monomer. It contains no residual silicon-hydrogen groups but retains some silylmethyl groups or vinyl groups from the (meth)acrylic monomer. It can be used in peroxide-curable silicone pressure-sensitive adhesives to enhance their release strength from substrates. DETAILED DESCRIPTION Example 1

[0014] Tackifier A1 was synthesized according to the following synthetic route:

[0015]

[0016] The specific synthesis process is as follows: the methyl-terminated hydrogenated silicone oil shown in the above synthesis route and toluene are added to a four-necked flask in a mass ratio of 1:1. At 80°C, allyl glycidyl ether mixed with 2 ppm of platinum (Speier catalyst for the entire reaction system) is slowly added dropwise through a constant pressure funnel. The dropping rate is controlled and the temperature is controlled below 100°C. After the addition is completed, the system temperature is maintained, and after sampling and testing for the absence of silicon-hydrogen structure, the product is subjected to 80°C and -0.095 MPa conditions. The toluene in the system is removed to obtain a colorless and transparent tackifier A1. Example 2

[0017] Tackifier A2 was synthesized according to the following synthetic route:

[0018]

[0019] The specific synthesis process is as follows: the methyl-terminated hydrogenated silicone oil in the above-mentioned synthesis route is added to a four-necked flask with toluene and isopropanol in a mass ratio of 2:1:1. At 80°C, an acrylic monomer (hydroxyethyl acrylate and trimethylolpropane formal acrylate in an equal molar ratio) mixed with 3 ppm of platinum (Speier catalyst for the entire reaction system) is added dropwise through a constant pressure funnel. The addition rate is controlled to maintain the temperature of the reaction system at no more than 100°C. After the addition is completed, the system temperature is maintained. After sampling and testing for the absence of silicon-hydrogen structure, the product is subjected to 80°C and a vacuum condition of -0.095 MPa to remove the toluene and isopropanol in the system to obtain the above-mentioned colorless and transparent tackifier A2. Example 3

[0020] Tackifier A3 was synthesized according to the following synthetic route:

[0021]

[0022] The specific synthesis process is as follows: the methylphenyl hydrogen silicone oil and 2-phenoxyethyl methacrylate required in the synthesis route are prepared into a mixture with a solid content of 50% by weight using toluene, and the mixture is added to a four-necked flask. At 90°C, 5 ppm of chloroplatinic acid catalyst is slowly dripped into the system. The material is first heated and then cooled, and the system temperature is maintained. After sampling and testing for the absence of silicon-hydrogen structure, the product is subjected to 90°C and -0.095 MPa conditions, and the toluene in the system is removed to obtain a colorless and transparent tackifier A3. Example 4

[0023] Tackifier A4 was synthesized as follows:

[0024]

[0025] The specific synthesis process is as follows: the methylphenyl-terminated hydrogen silicone oil and cyclohexanedimethanol diacrylate required by the above synthesis route are dissolved in toluene to form a mixture with a solid content of 50% by weight. The mixture is added to a four-necked flask. At 100°C, 5 ppm of chloroplatinic acid catalyst is slowly dripped into the system. The material is first heated and then cooled while maintaining the system temperature. After sampling and testing for the absence of silicon-hydrogen structure, the product is subjected to 100°C and a vacuum condition of -0.095 MPa to remove the toluene in the system to obtain tackifier A4. Example 5

[0026] Tackifier A5 was synthesized as follows:

[0027]

[0028] The specific synthesis process is as follows: the dimethyl diphenyl terminal hydrogen silicone oil and ethoxylated bisphenol A dimethacrylate required by the above synthesis route are dissolved in toluene to form a mixture with a solid content of 50% by weight and added to a four-necked flask. At 100°C, 5 ppm of chloroplatinic acid catalyst is slowly dripped into the system. The material is first heated and then cooled, and the system temperature is maintained. After sampling and testing for the absence of silicon-hydrogen structure, the product is subjected to 100°C and a vacuum condition of -0.095 MPa to remove the toluene in the system to obtain tackifier A5. Example 6

[0029] A peroxide-cured silicone pressure-sensitive adhesive is formulated as follows:

[0030] Blank group:

[0031] 107 glue 100g, molecular weight 800,000 (Shandong Dongyue);

[0032] MQ silicone resin 50g;

[0033] 225g of toluene.

[0034] Benzoyl peroxide 12g.

[0035] Experimental group: The tackifier prepared in Examples 1-4 was added to the blank group, and the tackifier accounted for 2% by weight of the total mass of the pressure-sensitive adhesive.

[0036] The pressure-sensitive adhesive (blank group) and the pressure-sensitive adhesive of the experimental group were coated on a PET film with a primer. The pressure-sensitive adhesive coating thickness was 20 μm. The pressure-sensitive adhesive was then attached to the object. The peel strength was tested after 24 hours.

[0037] Table 1. Peel force test results of blank group and experimental group

[0038]

[0039] The ratios in Table 1 are weight ratios. As shown in the table above, the peeling force of the pressure-sensitive adhesive with the addition of a tackifier to the substrate is significantly increased. The concept of the present invention can be used to select the appropriate type and group of tackifiers and apply them to peroxide-cured silicone pressure-sensitive adhesives to enhance their peeling force to the substrate.

[0040] It should also be noted that the components of the peroxide-cured silicone pressure-sensitive adhesive can vary and may include 80-120 parts by mass of 107 glue, 30-70 parts by mass of MQ silicone resin, 200-250 parts by mass of toluene, and 10-15 parts by mass of benzoyl peroxide, and the amount of tackifier added can then be calculated based on this. Example 7

[0041] A peroxide-cured organosilicon pressure-sensitive adhesive comprises 107 glue, MQ silicone resin, toluene, benzoyl peroxide and the tackifier described in Examples 1-5, wherein the tackifier accounts for 0.5% by weight of the total mass. Example 8

[0042] A peroxide-cured organosilicon pressure-sensitive adhesive comprises 107 glue, MQ silicone resin, toluene, benzoyl peroxide and the tackifier described in Examples 1-5, wherein the tackifier accounts for 5% by weight of the total mass.

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A tackifier for peroxide-cured silicone pressure-sensitive adhesive, characterized in that: Tackifier A1 was synthesized according to the following synthetic route: The methyl-terminated hydrogenated silicone oil and toluene shown in the above synthetic route were added to a reaction vessel in a mass ratio of 1:

1. Allyl glycidyl ether mixed with a platinum catalyst was slowly added dropwise through a constant pressure funnel at 80°C. The addition rate was controlled and the temperature was kept below 100°C. After the addition was completed, the system temperature was maintained, and a sample was taken for testing to confirm the absence of silicon-hydrogen structure. The toluene in the system was then removed to obtain a colorless and transparent tackifier A1. Tackifier A2 was synthesized according to the following synthetic route: Methyl-terminated hydrogenated silicone oil, toluene, and isopropanol were added to a four-necked flask in a mass ratio of 2:1:

1. An acrylic acid monomer mixed with a platinum catalyst was added dropwise through a constant pressure funnel at 80°C. The addition rate was controlled to maintain the temperature of the reaction system at no more than 100°C. After the addition was complete, the system temperature was maintained. After sampling and testing to determine if there was no silicon-hydrogen structure, the toluene and isopropanol in the system were removed to obtain the colorless and transparent tackifier A2. Tackifier A3 was synthesized according to the following synthetic route: A mixture of the methylphenyl hydrogenated silicone oil and 2-phenoxyethyl methacrylate in the synthetic route was prepared with toluene and added to a reaction vessel. Chloroplatinic acid catalyst was slowly added dropwise to the system at 90°C. The material was heated and then cooled, while the system temperature was maintained. After sampling and testing to confirm the absence of silicon-hydrogen structures, the toluene in the system was removed to obtain a colorless and transparent tackifier A3. Tackifier A4 was synthesized as follows: Methylphenyl-terminated hydrogen silicone oil and cyclohexanedimethanol diacrylate are dissolved in toluene to form a mixture, which is added to a reaction vessel. Chloroplatinic acid catalyst is slowly added dropwise to the system at 100°C. The material is heated and then cooled, and the system temperature is maintained. After sampling and testing to determine that there is no silicon-hydrogen structure, the toluene in the system is removed to obtain the tackifier product of the above route. Tackifier A5 was synthesized as follows: A mixture of dimethyl diphenyl hydrogen-terminated silicone oil and ethoxylated bisphenol A dimethacrylate was dissolved in toluene and added to a reaction vessel. Chloroplatinic acid catalyst was slowly added dropwise to the system at 100°C. The material was heated and then cooled while maintaining the system temperature. After sampling and testing to confirm the absence of silicon-hydrogen structure, the toluene in the system was removed to obtain tackifier A5.

2. Use of the tackifier according to claim 1 in a peroxide-cured silicone pressure-sensitive adhesive.

3. A peroxide-curable silicone pressure-sensitive adhesive, characterized in that: The invention comprises 107 glue, MQ silicone resin, toluene, benzoyl peroxide and the tackifier according to claim 1, wherein the tackifier according to claim 1 accounts for 0.5-5wt% of the total mass.

4. The peroxide-curable silicone pressure-sensitive adhesive according to claim 3, characterized in that: The invention comprises 80-120 parts by weight of 107 glue, 30-70 parts by weight of MQ silicone resin, 200-250 parts by weight of toluene and 10-15 parts by weight of benzoyl peroxide.

Images