Primer of silica gel composite cloth and preparation method thereof

Abstract

The invention discloses a primer for silica gel composite cloth and a preparation method thereof, and belongs to the technical field of primer and preparation thereof.The preparation method comprises the following steps that vinyl silicone oil and silazane are added into a reaction kettle and stirred, fumed silica is added after stirring, then deionized water is added and fully stirred, and after stirring is completed, heating and vacuumizing are conducted to prepare a base material A; dMC, hexamethyldisiloxane, deionized water and tetramethyl amine hydroxide are added into the reaction kettle, heating and stirring are conducted, the temperature is gradually increased, and silicone oil B is prepared; adding silicone oil B and a coupling agent KH560 into the reaction kettle, fully stirring, gradually adding fumed silica, adding deionized water, stirring, heating, and vacuumizing to obtain a base material C; and preparing the base material A, ethynyl cyclohexanol, chloroplatinic acid, silicone oil containing hydrogen at the end side, the base material C and vinyl silicone oil into the primer. According to the primer for the silica gel composite cloth and the preparation method of the primer, the prepared primer is good in storage stability and good in adhesive property.

Description

Technical Field

[0001] The invention relates to the technical field of primer and preparation thereof, in particular to a primer of a silicone composite cloth and a preparation method thereof. Background Art

[0002] Silicone rubber is widely used in aerospace, electronics, medical and other fields due to its excellent weather resistance, high and low temperature resistance and chemical stability. However, the bonding performance of traditional silicone rubber to fiber substrates (such as glass fiber cloth and aramid cloth) is insufficient, mainly because its non-polar properties make it difficult to form chemical bonds with the fiber surface. In the prior art, the bonding performance of deacidified silicone rubber is good, but the vulcanization by-products are corrosive; deketoxime silicone rubber has odor and metal corrosion problems; and although dealcoholized silicone rubber is environmentally friendly, there is still room for improvement in the bonding strength to the fiber substrate.

[0003] Silicone composite cloth is made by compounding fiber-based cloth with silicone rubber. It has both the mechanical strength of fiber and the flexibility of silicone rubber. However, its production process requires the reliance on high-efficiency primer to achieve stable bonding. Currently, commercially available primers generally have problems such as poor storage stability, insufficient deep curing, and poor adaptability to a variety of substrates. Therefore, it is of great value to develop a primer that is stable in storage, has excellent bonding properties, and is compatible with a variety of substrates. Summary of the invention

[0004] The purpose of the present invention is to provide a primer for a silicone composite cloth and a preparation method thereof, so as to solve the problems of poor storage stability, insufficient bonding strength and weak adaptability to diversified substrates of the existing primer.

[0005] To achieve the above object, the present invention provides a method for preparing a primer coating of a silicone composite cloth, comprising the following steps:

[0006] Step 1, preparing base material A: adding vinyl silicone oil and silazane into a reaction kettle and stirring thoroughly, adding fumed silica after stirring, adding deionized water after the addition of fumed silica is completed and stirring thoroughly, heating and vacuuming to obtain base material A after the stirring is completed;

[0007] Step 2, preparing silicone oil B: adding DMC, hexamethyldisiloxane and deionized water into a reaction kettle, adding tetramethylammonium hydroxide in a closed environment, heating and stirring while gradually increasing the temperature to obtain silicone oil B;

[0008] Step 3, preparing base material C: adding silicone oil B and coupling agent KH560 into a reaction kettle, gradually adding fumed silica after sufficient stirring, adding deionized water after the addition of fumed silica is completed, stirring, then heating and vacuuming to obtain base material C;

[0009] Step 4: Prepare the primer glue: Prepare the primer glue by mixing base material A, ethynylcyclohexanol, chloroplatinic acid, terminal-side hydrogen-containing silicone oil, base material C, and vinyl silicone oil.

[0010] Preferably, the dosages of the components in Step 1 are as follows: 50 - 100 parts of vinyl silicone oil, 5 - 15 parts of silicon nitride, 30 - 50 parts of fumed silica, and 5 - 15 parts of deionized water.

[0011] Preferably, the viscosity of the vinyl silicone oil in Step 1 is 500 Cst, the molecular weight is 17200, the vinyl content in the vinyl silicone oil is 0.2 - 0.4%, the stirring temperature before adding fumed silica is 25 - 50 °C, the stirring temperature after adding fumed silica is 80 - 100 °C, and the stirring time is 5 - 6 h.

[0012] Preferably, the dosages of the components in Step 2 are as follows: 80 - 100 parts of DMC, 3 - 5 parts of hexamethyldisiloxane, 1 - 2 parts of deionized water, and the concentration of tetramethylammonium hydroxide is 50 - 100 ppm.

[0013] Preferably, the stirring temperature in Step 2 is 100 - 110 °C, the stirring time is 4 - 6 h, the stirring speed is 10 - 15 r / min, and it is heated to 130 - 150 °C and kept at a constant temperature for 2 - 3 h.

[0014] Preferably, the dosages of the components in Step 3 are as follows: 80 - 100 parts of silicone oil B, 3 - 5 parts of coupling agent KH560, 15 - 20 parts of fumed silica, and 10 - 15 parts of deionized water.

[0015] Preferably, the stirring temperature in Step 3 is 25 - 50 °C, the stirring time after adding fumed silica is 5 - 6 h, it is heated to 80 - 100 °C after stirring, and the stirring time after vacuum pumping is 10 - 15 min.

[0016] Preferably, the dosages of the components in Step 4 are as follows: 55 - 60% of base material A, three ten-thousandths of ethynylcyclohexanol, 3 - 5% of terminal-side hydrogen-containing silicone oil, 20 - 30% of base material C, 10 - 15% of vinyl silicone oil, and 10 - 15 ppm of chloroplatinic acid.

[0017] The present invention also provides a primer glue for silicone composite fabric, which is prepared by using the preparation method of a primer glue for silicone composite fabric described above.

[0018] Therefore, by using the primer glue for silicone composite fabric and its preparation method described above, the primer glue for silicone composite fabric prepared has good storage stability, good bonding performance to various fiber substrates and various silicone materials; it also has beneficial effects such as better hardness, elongation at break, and deep curing.

[0019] The technical solution of the present invention is further described in detail below through embodiments. DETAILED DESCRIPTION

[0020] The technical solution of the present invention is further illustrated by the following examples.

[0021] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0022] The present invention provides a method for preparing a primer coating of a silicone composite cloth, comprising the following steps:

[0023] Step 1, preparing base material A: adding vinyl silicone oil and silazane into a reaction kettle and stirring thoroughly, adding fumed silica after stirring, adding deionized water after the addition of fumed silica is completed and stirring thoroughly, heating and vacuuming to remove by-products after stirring to obtain base material A;

[0024] The dosage of each component is: 50-100 parts of vinyl silicone oil, 5-15 parts of silazane, 30-50 parts of fumed silica, and 5-15 parts of deionized water. The viscosity of the vinyl silicone oil is 500Cst, the molecular weight is 17200, the vinyl content in the vinyl silicone oil is 0.2-0.4%, the stirring temperature before adding the fumed silica is 25-50°C, and the stirring temperature after the fumed silica is added is 80-100°C, and the stirring time is 5-6h.

[0025] The filling of fumed silica can ensure the strength of the prepared primer, with a specific surface area of ​​300m 2 / g vinyl silicone oil needs to be well surface treated, and silazane is used to make it non-polar methylated on the surface, so that more reinforcing material fumed silica can be filled. In the treatment of silazane, it needs to be completely hydrolyzed, so deionized water needs to be added and removed at high temperature and vacuum, which is beneficial to prevent excessive addition reaction from occurring later.

[0026] Step 2, preparing silicone oil B: adding DMC, hexamethyldisiloxane and deionized water into a reaction kettle, adding tetramethylammonium hydroxide in a closed environment, heating and stirring while gradually increasing the temperature to obtain silicone oil B;

[0027] The dosage of each component is: 80-100 parts of DMC, 3-5 parts of hexamethyldisiloxane, 1-2 parts of deionized water, and the concentration of tetramethylammonium hydroxide is 50-100 ppm.

[0028] The stirring temperature is 100-110°C, the stirring time is 4-6h, the stirring speed is 10-15r / min, the temperature is raised to 130-150°C and maintained at a constant temperature for 2-3h.

[0029] Step 3: Prepare base material C: Add silicone oil B and coupling agent KH560 into the reaction kettle. After fully stirring, gradually add fumed silica. After the addition of fumed silica is completed, when the stirring rate is greater than 800 r / min, add deionized water and stir. Then, heat up and evacuate to obtain base material C;

[0030] The dosage of each component is as follows: 80 - 100 parts of silicone oil B, 3 - 5 parts of coupling agent KH560, 15 - 20 parts of fumed silica, and 10 - 15 parts of deionized water.

[0031] The stirring temperature is 25 - 50 °C, the stirring time after adding fumed silica is 5 - 6 h, after stirring, heat up to 80 - 100 °C, and the stirring time after evacuation is 10 - 15 min.

[0032] Step 4: Prepare the primer: Prepare the primer by mixing base material A, ethynylcyclohexanol, chloroplatinic acid, terminal hydrogen-containing silicone oil, base material C, and vinyl silicone oil.

[0033] The dosage of each component in Step 4 is as follows: 50 - 60% of base material A, three ten-thousandths of ethynylcyclohexanol, 3 - 5% of terminal hydrogen-containing silicone oil, 20 - 30% of base material C, 10 - 15% of vinyl silicone oil, and 10 - 15 ppm of chloroplatinic acid. Among them, base material A is used to provide the body strength of the adhesive and form a colloid bridge, ethynylcyclohexanol is used to inhibit the catalyst for easy construction and coating, chloroplatinic acid is an addition reaction catalyst, terminal hydrogen-containing silicone oil cross-links with vinyl functional groups, and base material C and vinyl silicone oil adjust the viscosity and surface energy to facilitate wetting and adhesion to the substrate.

[0034] Example 1

[0035] The present invention provides a primer for silicone composite cloth, and its preparation method is as follows:

[0036] Step 1: Prepare base material A: 100 parts of vinyl silicone oil (vinyl content 0.4%) + 10 parts of silicon nitride + 50 parts of fumed silica + 10 parts of deionized water. The stirring temperature before adding fumed silica is 50 °C, and after adding fumed silica, stir at 100 °C for 5 h;

[0037] Step 2: Prepare silicone oil B: 100 parts of DMC + 4 parts of hexamethyldisiloxane + 1 part of deionized water + 100 ppm of tetramethylammonium hydroxide, keep at a constant temperature of 140 °C for 2 h;

[0038] Step 3: Prepare base material C: 100 parts of silicone oil B + 5 parts of KH560 + 20 parts of fumed silica + 10 parts of deionized water, evacuate at 100 °C for 15 min;

[0039] Step 4: Prepare the primer: 60% of base material A + 5% in total of terminal-side hydrogen-containing silicone oil, ethynylcyclohexanol, chloroplatinic acid (where ethynylcyclohexanol is 0.03% and chloroplatinic acid is 10 ppm) + 25% of base material C + 10% of vinyl silicone oil.

[0040] Example 2

[0041] Adjust the dosage of base material A in Step 4 to 55%, and the rest is the same as in Example 1.

[0042] Example 3

[0043] Adjust the dosage of base material C in Step 4 to 20%, and the rest is the same as in Example 1.

[0044] Comparative Example 1

[0045] The only difference between Comparative Example 1 and Example 1 is that: in Step 4, the dosage of base material A is 50%, and the dosage of base material C is 35%, and the rest of the conditions are the same as in Example 1.

[0046] Performance test:

[0047] Measure the samples obtained in Example 1 and Comparative Example 1, and compare the curing time, curing temperature, and peel strength N / 25mm of the products prepared in Example 1 and Comparative Example 1 on fiberglass cloth, polyester fiber cloth, aramid cloth, and carbon fiber. The room-temperature curing test results are shown in Table 1, and the 70°C / 7-day aging test results are shown in Table 2:

[0048] Table 1 Room-temperature curing test results

[0049] Room Temperature Curing Test Items Example 1 Comparative Example 1 Curing Time / s 68 93 Curing Temperature / °C 160 160 Carbon Fiber 55 63 Glass Fiber 70 70 Aramid Fabric 89 103 Polyester Fiber Fabric 87 90

[0050] Table 2 70°C / 7-day aging test results

[0051]

[0052] It can be seen from the test results in Table 1 and Table 2 that by comparing the base material ratios in the two primers, the epoxy modification has a relatively large impact on the bonding performance of the sealant. With the increase of the epoxy amount, the bonding performance is improved, but the curing speed decreases accordingly. In the accelerated storage aging test, although the increase in the epoxy amount leads to a decrease in the storage stability of the primer, it is still within the acceptable range. The primer will show a slow vulcanization phenomenon after being stored for a period of time, and the vulcanization rate and mechanical properties of the primer are not greatly affected by the storage temperature and time under the experimental conditions.

[0053] Therefore, by using the above-mentioned primer for silicone composite cloth and its preparation method, the prepared high-temperature vulcanized organic primer has good storage stability, good bonding performance for various fiber substrates and various silicone materials; it also has beneficial effects of good hardness, elongation at break, and deep curing.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions of the present invention or make equivalent replacements, and these modifications or equivalent replacements do not enable the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a primer for a silicone composite cloth, characterized in that: The following steps are involved: Step 1, preparing base material A: adding vinyl silicone oil and silazane into a reaction kettle and stirring thoroughly, adding fumed silica after stirring, adding deionized water after the addition of fumed silica is completed and stirring thoroughly, heating and vacuuming to obtain base material A after the stirring is completed; Step 2, preparing silicone oil B: adding DMC, hexamethyldisiloxane and deionized water into a reaction kettle, adding tetramethylammonium hydroxide in a closed environment, heating and stirring while gradually increasing the temperature to obtain silicone oil B; Step 3, preparing base material C: adding silicone oil B and coupling agent KH560 into a reaction kettle, gradually adding fumed silica after sufficient stirring, adding deionized water after the addition of fumed silica is completed, stirring, then heating and vacuuming to obtain base material C; Step 4, preparing the primer: prepare the primer by mixing base material A, ethynyl cyclohexanol, chloroplatinic acid, end-side hydrogen-containing silicone oil, base material C, and vinyl silicone oil.

2. The method for preparing a primer for a silicone composite cloth according to claim 1, characterized in that: The dosage of each component in step 1 is: 50-100 parts of vinyl silicone oil, 5-15 parts of silazane, 30-50 parts of fumed silica, and 5-15 parts of deionized water.

3. The method for preparing a primer for a silicone composite cloth according to claim 1, characterized in that: In step 1, the viscosity of the vinyl silicone oil is 500Cst, the molecular weight is 17200, the vinyl content in the vinyl silicone oil is 0.2-0.4%, the stirring temperature before adding the fumed silica is 25-50°C, the stirring temperature after adding the fumed silica is 80-100°C, and the stirring time is 5-6h.

4. The method for preparing a primer for a silicone composite cloth according to claim 1, characterized in that: The dosage of each component in step 2 is: 80-100 parts of DMC, 3-5 parts of hexamethyldisiloxane, 1-2 parts of deionized water, and the concentration of tetramethylammonium hydroxide is 50-100 ppm.

5. The method for preparing a primer for a silicone composite cloth according to claim 1, characterized in that: In step 2, the stirring temperature is 100-110° C., the stirring time is 4-6 hours, the stirring speed is 10-15 r / min, the temperature is raised to 130-150° C. and maintained at a constant temperature for 2-3 hours.

6. The method for preparing a primer for a silicone composite cloth according to claim 1, characterized in that: The dosage of each component in step 3 is: 80-100 parts of silicone oil B, 3-5 parts of coupling agent KH560, 15-20 parts of fumed silica, and 10-15 parts of deionized water.

7. The method for preparing a primer for a silicone composite cloth according to claim 1, characterized in that: In step 3, the stirring temperature is 25-50° C., the stirring time after adding the fumed silica is 5-6 hours, the temperature is raised to 80-100° C. after stirring, and the stirring time after vacuuming is 10-15 minutes.

8. The method for preparing a primer for a silicone composite cloth according to claim 1, characterized in that: The dosage of each component in step 4 is: 55-60% base material A, 0.3 parts per million of ethynyl cyclohexanol, 3-5% of end-side hydrogenated silicone oil, 20-30% base material C, 10-15% of vinyl silicone oil and 10-15 ppm of chloroplatinic acid.

9. A primer for a silicone composite cloth, characterized in that: The silicone composite cloth is prepared by the method for preparing a primer adhesive for silicone composite cloth according to any one of claims 1 to 8.

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