A primer for addition-type silicone rubber and a method for preparing the same

Abstract

The application discloses a primer for addition type silicone rubber and a preparation method thereof. The primer for addition type silicone rubber comprises, in parts by weight, 10 parts of dimer acid polyester dihydric alcohol, 0.5-10 parts of diisocyanate, 0.2-2 parts of polyisocyanate, 0.2-2 parts of isocyanate propyl trimethoxysilane, 0.1-1 part of vinyl trimethoxysilane, 0.1-0.2 part of N, N-diethyl-3-aminopropyl trimethoxysilane, 0.01-0.05 part of titanate catalyst and 200-800 parts of organic solvent. The primer for addition type silicone rubber has excellent adhesion to most substrates, and can form a bond with the addition type silicone rubber at room temperature, so that the addition type silicone rubber has adhesion, excellent high-temperature resistance and moisture resistance. In addition, the primer is easy to spray and convenient to operate.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and particularly relates to a curable addition-type silicone rubber primer and its preparation method. Background Technology

[0002] Compared to condensation-type silicone rubber, addition-cure silicone rubber exhibits superior weather resistance and aging resistance. In everyday industrial production, applications such as electrical insulation, industrial molding, and thermally conductive potting and sealing of electronic appliances are increasingly being used and developed. However, due to its unique hydrosilylation curing mechanism, its adhesion to substrates is not ideal. Generally, addition-cure silicone rubber can be cured at room temperature or at high temperatures. Room temperature curing results in no adhesion, while high-temperature curing may provide some adhesion, but this limits the application of substrates, as most plastic materials cannot be heated.

[0003] Primers, acting as a bridge between the substrate and silicone rubber, enhance the adhesion of addition-cure silicone rubber to the substrate, playing a crucial role in its application. Most primers for addition-cure silicone rubber on the market primarily focus on improving adhesion after medium to high temperature curing, while primers for room-temperature curing addition-cure silicone rubber are relatively rare. Summary of the Invention

[0004] The main objective of this invention is to provide a primer for addition-cure silicone rubber and its preparation method, aiming to solve the technical problem of how to bond the substrate and addition-cure silicone rubber under normal temperature conditions.

[0005] To achieve the above objectives, the present invention provides a primer for addition-cure silicone rubber, comprising, by weight parts:

[0006] 10 parts of dimerized polyester diol;

[0007] 0.5-10 parts of diisocyanate;

[0008] Polyisocyanate 0.2~2 parts;

[0009] 0.2-2 parts of isocyanate-propyltrimethoxysilane;

[0010] Vinyltrimethoxysilane 0.1~1 part;

[0011] 0.1 to 0.2 parts of N,N-diethyl-3-aminopropyltrimethoxysilane;

[0012] 0.01 to 0.05 parts of titanate catalyst; and,

[0013] Organic solvents: 200-800 parts.

[0014] Optionally, the number average molecular weight of the dimer acid polyester diol is 500 to 8000.

[0015] Optionally, the diisocyanate is one or more of isophorone diisocyanate and diphenylmethane diisocyanate.

[0016] Optionally, the polyisocyanate is a mixture of a highly functional isocyanate and a diphenylmethane diisocyanate.

[0017] Optionally, the organic solvent is one or more selected from ethyl acetate, toluene, petroleum ether, and acetone.

[0018] Optionally, the titanate catalyst is one of bis(ethyl acetoacetate) titanate diisopropyl, ethyl acetoacetate titanate triisopropyl, bis(ethyl acetoacetate) titanate dibutyl, and ethyl acetoacetate titanate tributyl.

[0019] The present invention also proposes a method for preparing the above-mentioned primer for addition-cure silicone rubber, the preparation method comprising the following steps:

[0020] The dimer acid polyester diol was subjected to vacuum dehydration treatment;

[0021] Then add diisocyanate, polyisocyanate, and isocyanate-propyltrimethoxysilane to carry out the reaction;

[0022] Then add an organic solvent to dilute it;

[0023] Then, vinyltrimethoxysilane, N,N-diethyl-3-aminopropyltrimethoxysilane, and titanate catalyst are added and mixed to obtain a primer for addition-type silicone rubber.

[0024] Optionally, in the step of vacuum dehydrating the dimer polyester diol, the temperature of the vacuum dehydration treatment is 100~120℃.

[0025] Optionally, in the step of vacuum dehydrating the dimer acid polyester diol, the vacuum dehydration time is 1-3 hours.

[0026] In the step of vacuum dehydrating the dimer polyester diol, the reaction temperature is 60-80°C in the step of adding diisocyanate, polyisocyanate, and isocyanate-propyltrimethoxysilane for reaction.

[0027] In the step of vacuum dehydrating the dimer polyester diol, the reaction time is 1-3 hours in the step of adding diisocyanate, polyisocyanate, and isocyanate-propyltrimethoxysilane for reaction.

[0028] The primer for addition-cure silicone rubber in this technical solution exhibits excellent adhesion to most substrates and can form a bond with addition-cure silicone rubber at room temperature, thus providing the addition-cure silicone rubber with adhesive properties. It also possesses excellent high-temperature and damp-heat resistance. Furthermore, this primer is easy to spray and convenient to apply. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic flowchart of an embodiment of the preparation method of the addition-cure silicone rubber primer provided by the present invention.

[0031] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them.

[0033] It should be noted that, unless specific conditions are specified in the embodiments, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products. Furthermore, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution that simultaneously satisfies A and B. In addition, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, such a combination should be considered non-existent and not within the scope of protection claimed by this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention.

[0034] Primers, acting as a bridge between the substrate and silicone rubber, enhance the adhesion of addition-cure silicone rubber to the substrate, playing a crucial role in its application. Most primers for addition-cure silicone rubber on the market primarily focus on improving adhesion after medium to high temperature curing, while primers for room-temperature curing addition-cure silicone rubber are relatively rare.

[0035] In view of this, the present invention provides a primer for addition-cure silicone rubber, which can form a bond with addition-cure silicone rubber at room temperature, comprising, by weight:

[0036] 10 parts of dimerized polyester diol;

[0037] 0.5-10 parts of diisocyanate;

[0038] Polyisocyanate 0.2~2 parts;

[0039] 0.2-2 parts of isocyanate-propyltrimethoxysilane;

[0040] Vinyltrimethoxysilane 0.1~1 part;

[0041] 0.1 to 0.2 parts of N,N-diethyl-3-aminopropyltrimethoxysilane;

[0042] 0.01 to 0.05 parts of titanate catalyst; and,

[0043] Organic solvents: 200-800 parts.

[0044] In this technical solution, the primer for addition-cure silicone rubber prepared with the above-mentioned components exhibits excellent adhesion to most substrates and can form a bond with addition-cure silicone rubber at room temperature, thus giving the addition-cure silicone rubber adhesive properties. It also possesses excellent high-temperature and damp-heat resistance. Furthermore, this primer is easy to spray and convenient to use.

[0045] In some embodiments of the present invention, the number average molecular weight of the dimer acid polyester diol is 500 to 8000.

[0046] In some embodiments of the present invention, the diisocyanate is one or more of isophorone diisocyanate and diphenylmethane diisocyanate.

[0047] In some embodiments of the present invention, the polyisocyanate is polymeric MDI, which is a mixture prepared by mixing a high-functionality isocyanate with diphenylmethane diisocyanate (MDI) in a weight ratio of 1:1 to 3:1.

[0048] In some embodiments of the present invention, the organic solvent is one or more of ethyl acetate, toluene, petroleum ether, and acetone.

[0049] In some embodiments of the present invention, the titanate catalyst is one of bis(ethyl acetoacetate) titanate diisopropyl ester, ethyl acetoacetate titanate triisopropyl ester, bis(ethyl acetoacetate) titanate dibutyl ester, and ethyl acetoacetate titanate tributyl ester.

[0050] The present invention also proposes a method for preparing the above-mentioned primer for addition-cure silicone rubber, the preparation method comprising the following steps.

[0051] Step S10: Vacuum dehydration treatment of the dimer acid polyester diol.

[0052] In some embodiments of the present invention, 10 parts by weight (the same below) of dimer polyester diol are vacuum dehydrated at 100~120°C for 1~3 hours, and then placed in a container.

[0053] Step S20: Add diisocyanate, polyisocyanate, and isocyanate-propyltrimethoxysilane to carry out the reaction.

[0054] In some embodiments of the present invention, 0.5-10 parts of diisocyanate, 0.2-2 parts of polyisocyanate, and 0.2-2 parts of isocyanate-propyltrimethoxysilane are added to the container and mixed at a temperature of 60-80°C for 1-3 hours for addition polymerization. In some preferred embodiments, 1-5 parts of diisocyanate, 0.1-1 parts of polyisocyanate, and 0.2-2 parts of isocyanate-propyltrimethoxysilane are added for addition reaction.

[0055] Step S30: Add an organic solvent to dilute the product.

[0056] In some embodiments of the present invention, 200-800 parts of an organic solvent are added to the container for dilution. The organic solvent is one or more selected from ethyl acetate, toluene, petroleum ether, and acetone. In some preferred embodiments, 200-550 parts of an organic solvent are added for dilution.

[0057] Step S40: Add vinyltrimethoxysilane, N,N-diethyl-3-aminopropyltrimethoxysilane, and titanate catalyst, and mix to obtain a primer for addition-type silicone rubber.

[0058] In some embodiments of the present invention, 0.1 to 1 part of vinyltrimethoxysilane, 0.1 to 0.2 parts of N,N-diethyl-3-aminopropyltrimethoxysilane and 0.01 to 0.05 parts of titanate catalyst are added to the container and stirred thoroughly to obtain a primer for addition-type silicone rubber.

[0059] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0060] In the following embodiments, the drug information used is as follows:

[0061] Dimeric acid polyester diol was produced by Shanghai Jingri New Material Technology Co., Ltd.; diisocyanate and polyisocyanate were produced by Wanhua Chemical Group Co., Ltd.; isocyanate-based propyltrimethoxysilane, vinyltrimethoxysilane, N,N-diethyl-3-aminopropyltrimethoxysilane, and titanate catalyst were produced by Nanjing Nengde New Material Technology Co., Ltd.; ethyl acetate was produced by Tianjin Ruijinte Chemical Co., Ltd.; petroleum ether was produced by Jiangsu Tongsheng Chemical Reagent Co., Ltd.; and toluene and acetone were produced by Hangzhou Gaojing Fine Chemical Co., Ltd. Example 1

[0062] 200g of dimer polyester diol with a number average molecular weight of 1000 was placed in a container and vacuum dehydrated at 110℃ for 2h; 88g of isophorone diisocyanate, 15g of polyisocyanate mixed in a 3:1 weight ratio, and 8.2g of isocyanate-propyltrimethoxysilane were added and reacted at 70℃ for 2h; then 6000g of ethyl acetate solvent was added for dilution; 6g of vinyltrimethoxysilane, 2.4g of N,N-diethyl-3-aminopropyltrimethoxysilane, and 0.4g of bis(ethyl acetoacetate) titanate diisopropyl ester catalyst were added; the mixture was stirred to obtain a primer for addition-type silicone rubber with a solid content of about 5%. Example 2

[0063] 200g of dimer polyester diol with a number average molecular weight of 500 was placed in a container and vacuum dehydrated at 100℃ for 3h; 200g of diphenylmethane diisocyanate, 30.6g of polyisocyanate mixed in a 3:1 weight ratio, and 24g of isocyanate-propyltrimethoxysilane were added and reacted at 100℃ for 2.5h; then 11000g of toluene solvent was added for dilution; 8g of vinyltrimethoxysilane, 4g of N,N-diethyl-3-aminopropyltrimethoxysilane, and 0.3g of ethyl acetoacetate titanate triisopropyl ester catalyst were added; the mixture was stirred to obtain a primer for addition-type silicone rubber with a solid content of about 4%. Example 3

[0064] 200g of dimer polyester diol with a number average molecular weight of 4000 was placed in a container and vacuum dehydrated at 120℃ for 2h; 50.5g of isophorone diisocyanate, 20g of polyisocyanate mixed in a 3:1 weight ratio, and 10g of isocyanate-propyltrimethoxysilane were added and reacted at 80℃ for 2h; then a mixed solvent of 2800g petroleum ether and 2800g ethyl acetate was added for dilution; 12g of vinyltrimethoxysilane, 4g of N,N-diethyl-3-aminopropyltrimethoxysilane, and 0.5g of dibutyl bis(ethyl acetoacetate) titanate catalyst were added; the mixture was stirred to obtain a primer for addition-type silicone rubber with a solid content of about 5%. Example 4

[0065] 200g of dimer polyester diol with a number average molecular weight of 8000 was placed in a container and vacuum dehydrated at 120℃ for 3h; 15.8g of diphenylmethane diisocyanate, 8g of polyisocyanate mixed in a 3:1 weight ratio, and 36g of isocyanate-propyltrimethoxysilane were added and reacted at 80℃ for 2h; then 6800g of acetone solvent was added for dilution; 8g of vinyltrimethoxysilane, 4g of N,N-diethyl-3-aminopropyltrimethoxysilane, and 0.5g of ethyl acetoacetate titanate triisopropyl ester catalyst were added; the mixture was stirred to obtain a primer for addition-type silicone rubber with a solid content of about 4%. Example 5

[0066] 200g of dimer polyester diol with a number average molecular weight of 2000 was placed in a container and vacuum dehydrated at 110℃ for 2h; 60g of isophorone diisocyanate, 22.4g of polyisocyanate mixed in a 3:1 weight ratio, and 6g of isocyanate-propyltrimethoxysilane were added and reacted at 80℃ for 2h; then 6000g of ethyl acetate solvent was added for dilution; 4g of vinyltrimethoxysilane, 2.2g of N,N-diethyl-3-aminopropyltrimethoxysilane, and 0.36g of bis(ethyl acetoacetate) titanate diisopropyl ester catalyst were added; the mixture was stirred to obtain a primer for addition-type silicone rubber with a solid content of about 5%. Example 6

[0067] 200g of dimer polyester diol with a number average molecular weight of 3000 was placed in a container and vacuum dehydrated at 120℃ for 1.5h; 42g of diphenylmethane diisocyanate, 30g of polyisocyanate mixed in a 3:1 weight ratio, and 20g of isocyanate-propyltrimethoxysilane were added and reacted at 60℃ for 3h; then, a mixed solvent of 3800g ethyl acetate and 3800g toluene was added for dilution; 6g of vinyltrimethoxysilane, 6g of N,N-diethyl-3-aminopropyltrimethoxysilane, and 0.6g of ethyl acetoacetate titanate triisopropyl ester catalyst were added; the mixture was stirred to obtain a primer for addition-type silicone rubber with a solid content of about 4%.

[0068] Comparative Example 1

[0069] (1) Place 100g of polycarbonate polyol with a number average molecular weight of 500 into a container, dehydrate it at 100°C for 3 hours, and then cool it down to 60°C.

[0070] (2) Add 69.65g of toluene diisocyanate, stir, and react for 4 hours under nitrogen protection;

[0071] (3) Heat to 80°C, and add 46.44 g of hydroxyethyl acrylate dropwise over 1 hour while stirring. After the addition is complete, continue the reaction at 80°C for 2 hours.

[0072] (4) Cool down to 50℃, add 2325mL xylene, and stir until well mixed.

[0073] (5) After cooling to room temperature, add 11.2g of Sperier catalyst with a Pt content of 3000ppm and stir evenly.

[0074] A primer A1 for addition-type silicone rubber was obtained.

[0075] Comparative Example 2

[0076] 50g of tetrabutyl titanate, 50g of tetraethyl silicate, and 1.2g of acetic acid were placed in a container and stirred evenly at room temperature. After stirring and reacting for 5 hours at 60°C, the temperature was raised to 80°C and the low-boiling substances were removed by vacuum distillation to obtain titanate-silicate oligomer B1.

[0077] Add 1.8g titanate-silicate oligomer B1, 0.8g KH560, 0.8g allyltrimethoxysilane, and 1g epoxy-modified silicone resin to 100g of n-heptane solvent. Stir until homogeneous and at room temperature for 20 minutes.

[0078] A primer B2 for addition-type silicone rubber was obtained.

[0079] [Performance Evaluation]

[0080] The primers obtained in Examples 1-6 and Comparative Examples 1-2 were absorbed by degreased cotton and applied in groups to 304# stainless steel and anodized aluminum sheets. After waiting for 10 minutes, the solvent evaporated, and Runhe addition-type silicone rubber mold glue was applied to each sheet.

[0081] Shear plates were prepared according to the method in GB / T 7124-2008 Determination of tensile shear strength of adhesives (rigid material to rigid material) and tested for shear strength after curing at room temperature for 3 days. The results are shown in Table 1.

[0082] Table 1. Test results of adhesive performance of primer for silicone rubber.

[0083]

[0084] As can be seen from Table 1, the primer for addition-cure silicone rubber prepared in this invention has a great promoting effect on the adhesion of ordinary addition-cure silicone rubber.

[0085] Samples from Examples 1 and 2 and Comparative Examples 1 and 2, cured at room temperature for 3 days, were placed in an aging test chamber. After setting the parameters of the following aging conditions, shear plates were prepared according to the method of GB / T 7124-2008 Determination of tensile shear strength of adhesives (rigid material to rigid material) and shear strength was tested after 7 days. The results are shown in Table 2.

[0086] Table 2. Results of high temperature resistance and damp heat aging tests for Examples 1 and 2

[0087]

[0088] As can be seen from Table 2, the addition-type silicone rubber primer prepared by the present invention exhibits very little change in shear strength during aging tests, and has good high-temperature resistance and damp heat resistance.

[0089] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0090] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A primer for addition-cure silicone rubber, characterized in that, Included by weight parts: 10 parts of dimerized polyester diol; 0.5-10 parts of diisocyanate; Polyisocyanate 0.2~2 parts; 0.2-2 parts of isocyanate-propyltrimethoxysilane; Vinyltrimethoxysilane 0.1~1 part; 0.1 to 0.2 parts of N,N-diethyl-3-aminopropyltrimethoxysilane; 0.01 to 0.05 parts of titanate catalyst; and, Organic solvent 200-800 parts; The number-average molecular weight of the dimer acid polyester diol is 500-8000; The diisocyanate is one or more of isophorone diisocyanate and diphenylmethane diisocyanate; The polyisocyanate is polymeric MDI, which is a mixture prepared by mixing high-functionality isocyanate and diphenylmethane diisocyanate in a weight ratio of 1:1 to 3:

1. The titanate catalyst is one of bis(ethyl acetoacetate) titanate diisopropyl ester, ethyl acetoacetate titanate triisopropyl ester, bis(ethyl acetoacetate) titanate dibutyl ester, and ethyl acetoacetate titanate tributyl ester. The preparation method of the primer for addition-cure silicone rubber includes the following steps: The dimer acid polyester diol was subjected to vacuum dehydration treatment; Then add diisocyanate, polyisocyanate, and isocyanate-propyltrimethoxysilane to carry out the reaction; Then add an organic solvent to dilute it; Then, vinyltrimethoxysilane, N,N-diethyl-3-aminopropyltrimethoxysilane, and titanate catalyst are added and mixed evenly to obtain a primer for addition-type silicone rubber.

2. The primer for addition-cure silicone rubber as described in claim 1, characterized in that, The organic solvent is one or more of ethyl acetate, toluene, petroleum ether, and acetone.

3. A method for preparing a primer for addition-cure silicone rubber as described in any one of claims 1-2, characterized in that, The preparation method includes the following steps: The dimer acid polyester diol was subjected to vacuum dehydration treatment; Then add diisocyanate, polyisocyanate, and isocyanate-propyltrimethoxysilane to carry out the reaction; Then add an organic solvent to dilute it; Then, vinyltrimethoxysilane, N,N-diethyl-3-aminopropyltrimethoxysilane, and titanate catalyst are added and mixed evenly to obtain a primer for addition-type silicone rubber.

4. The method for preparing the primer for addition-cure silicone rubber as described in claim 3, characterized in that, In the step of vacuum dehydrating the dimerized polyester diol, the temperature of the vacuum dehydration treatment is 100~120℃; the time of the vacuum dehydration treatment is 1~3h.

5. The method for preparing the primer for addition-cure silicone rubber as described in claim 3, characterized in that, In the step of adding diisocyanate, polyisocyanate, and isocyanate-propyltrimethoxysilane for reaction, the reaction temperature is 60~80℃.

6. The method for preparing the primer for addition-cure silicone rubber as described in claim 3, characterized in that, In the step of adding diisocyanate, polyisocyanate, and isocyanate-propyltrimethoxysilane for reaction, the reaction time is 1-3 hours.

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