Silicone rubber with improved surface viscosity and preparation method thereof

Abstract

The invention relates to a silicone rubber with improved surface viscosity and a preparation method thereof. The method comprises a first rubber mixing step, a second rubber mixing step and a third rubber mixing step to obtain an addition type rubber material; and further comprises a vulcanization step, in which a platinum catalyst, a hydrogen-containing polysiloxane containing Si-H in a side chain, liquid ammonia and 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane are added again to the addition type rubber material, and vulcanization is carried out at 100-130°C to obtain the silicone rubber with improved surface viscosity.

Description

Technical Field

[0001] The invention relates to the field of rubber composition and manufacturing, in particular to a silicone rubber with improved surface viscosity and a preparation method thereof. The prepared rubber composition is particularly suitable for preparing composite components of rubber and plastic. Background Art

[0002] Silicone rubber materials have attracted wide attention due to their good tensile and insulation properties and reliable mechanical endurance. It is known that the rubber material has a wear resistance, compression resistance, tensile strength and other mechanical properties greatly improved by increasing its cross-linking degree through the vulcanization step.

[0003] However, in the fields of engineering electrical, automobiles, etc., rubber materials alone often cannot adapt to complex working conditions, and often require the compounding of rubber with other materials. At this time, the adhesion between rubber and other materials, especially engineering plastic materials, has become a topic of rubber material research. For example, Chinese patent publication CN103756329A relates to an insulating rubber and preparation method for power cable accessories. This patented technology provides rubber materials with good elasticity, deformation performance and hydrophobic properties. However, this type of technology does not take into account the reliability of composite cable accessories when connected to other accessories such as plastics during use.

[0004] Therefore, there is still a huge demand for research and development and improvement in related fields and technologies. Summary of the invention

[0005] The present invention focuses on providing a silicone rubber with improved surface viscosity and a preparation method thereof. The method and the rubber composition are suitable for composite components of rubber and plastic.

[0006] A first aspect of the present invention provides a method for preparing a silicone rubber having improved surface viscosity, the method comprising the following steps:

[0007] Step 1) First rubber mixing step: select terminal vinyl polysiloxane, side chain vinyl polysiloxane (viscosity 500-800mPa·s), white carbon black, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, 1-ethynyl-1-cyclohexanol, and knead them at room temperature; then heat to 100-150° C., and knead again under an inert atmosphere to obtain a first mixed rubber;

[0008] Step 2) second rubber mixing step: adding 1-ethynyl-1-cyclohexanol again to the first rubber mix, and continuing to mix the rubber in an open mixing mill to obtain a second rubber mix;

[0009] Step 3) a third rubber mixing step: adding a platinum catalyst to the second mixed rubber, and continuing mixing under an inert atmosphere and vacuum conditions to obtain an addition type rubber material;

[0010] Step 4) vulcanization step: Add platinum catalyst, hydrogen-containing polysiloxane with Si-H side chain, liquid ammonia, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane to the addition type rubber material again, and vulcanize at 100-130° C. to obtain silicone rubber with improved surface viscosity.

[0011] In a preferred technical solution, the method further comprises the following specific steps:

[0012] In the step 1), 50-150 parts by weight of a terminal vinyl polysiloxane having a vinyl content of 0.01-0.03% (mol) and a molecular weight of 10,000 to 30,000, 5-15 parts by weight of a side chain vinyl polysiloxane having a vinyl content of 0.01-0.03% (mol), 10-50 parts by weight of a first white carbon black (300-350m 2 / g, BET method) and 2-10 parts by weight of a second white carbon black (100-150 m 2 / g, BET method), 1-3 parts by weight of 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, and 1-5 parts by weight of 1-ethynyl-1-cyclohexanol are added into a kneader for kneading; after the material is in a solid block, the temperature is raised to 130-140° C., and the kneading is continued for 20 minutes under an air pressure of 0.01-0.05 MPa, and the material is discharged to obtain the first mixed rubber.

[0013] In a preferred technical solution, the method further comprises the following specific steps:

[0014] In the step 2), 0.5-5 parts by weight of 1-ethynyl-1-cyclohexanol are added to 100 parts by weight of the first rubber mix, and the rubber mix is ​​continued in an open mixing mill for 30-60 minutes to obtain a second rubber mix.

[0015] In a preferred embodiment, the method further comprises the following specific steps:

[0016] In the step 3), 0.5-2 parts by weight of divinyltetramethyldisiloxane platinum complex having a platinum content of 1000ppm-1500ppm is added to 100 parts by weight of the second mixed rubber, and the mixing is continued for 1-2 hours in an inert atmosphere at an air pressure of 0.01-0.05MPa to obtain the addition type rubber material.

[0017] In a preferred embodiment, in step 4), 0.5-2 parts by weight of divinyltetramethyldisiloxane platinum complex having a platinum content of 2000ppm-4000ppm, 5-20 parts by weight of hydrogen-containing polysiloxane having a hydrogen content of 10mmol / g and containing Si-H in the side chain, 0.1-2 parts by weight of liquid ammonia, and 1-5 parts by weight of 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane are added to 100 parts by weight of the addition type rubber material, and vulcanization is carried out at 110°C to 130°C to obtain a silicone rubber product with a surface adhesiveness containing a vulcanization system.

[0018] A second aspect of the present invention provides a silicone rubber composition for improving surface adhesion, characterized in that the silicone rubber composition is prepared according to any one of the methods provided in the above technical solutions.

[0019] The rubber composition obtained by the preparation process of the present invention has good mechanical properties and electrical resistance characteristics, and in particular has good adhesion to engineering plastics.

[0020] It should be noted that the product and process of the present invention may include the above steps and other related steps. In an optional or preferred scheme, the scheme of the present invention may only include the above steps or components, no longer include other steps and components, or do not significantly include other main steps or main components. In addition, the steps should be performed in a sequential order in the optional scheme, and the components and steps of the present invention can be implemented independently or arbitrarily superimposed and combined with each other.

[0021] In the following, the technical solutions and advantages of the present invention will be explained and described in more detail in conjunction with specific implementation methods. It should be understood that the contents presented in the specification and specific implementation methods are only for the purpose of more clearly illustrating the technical solutions and advantages of the present invention, and do not limit the protection scope of the present invention. Those skilled in the art can obtain the changed technical solutions based on the disclosure of the specification for various reasonable transformations. As long as they do not deviate from the spirit of the present invention, the various changed technical solutions should be understood to be included in the protection scope of the present invention. DETAILED DESCRIPTION

[0022] The present invention is described in more detail hereinafter to facilitate understanding of the invention.

[0023] Before describing the specific implementation scheme, it should be noted that those skilled in the art can select appropriate raw materials according to the enlightenment and teaching of the present disclosure, and use relevant testing equipment to perform relevant tests and obtain corresponding results. For raw materials without specific manufacturers or pathways, those skilled in the art can select raw materials that meet corresponding requirements as reaction starting materials according to the disclosure and requirements of this specification. The reaction raw materials of the process part compounds are derived from the initial products synthesized in the preamble step of the present invention, which can also be understood according to the present disclosure.

[0024] Table 1 lists the main raw materials used in the present invention and the corresponding acquisition channels or raw material origins. It should be noted that the raw materials not described in the present invention are raw material varieties that can be obtained by those skilled in the art based on common technical knowledge and existing market products.

[0025] Table 1: Description of the main raw materials used in the present invention

[0026]

[0027]

[0028] In a typical experiment to test adhesion, the hot vulcanization adhesion of addition silicone rubber and engineering plastic PPS is tested. The PPS used is a 1mm thick flat sheet, which is cleaned and treated with acetone solvent before hot vulcanization bonding of the addition silicone rubber. The treated PPS flat sheet is placed in the cavity, and then the mixed rubber obtained by the preparation example and the comparative example corresponding to the embodiment is placed respectively, and molded on a flat vulcanizer to obtain a sample for testing adhesion. The thickness of the silicone rubber vulcanizate in the sample is about 0.15mm. The test of the peeling area follows the principle of the hundred-grid test, that is, after a hundred grids are drawn on one side of the vulcanizate of the obtained layered composite, it is vertically suspended and / or scraped (scratching force 0.2N / m), and then the peeling area is observed and measured.

[0029] Example 1

[0030] In a typical embodiment of the present invention, the silicone rubber composition for improving surface adhesion of the present invention is made from the raw materials described below and through the specific process described. However, it is clear to those skilled in the art that, based on the contents disclosed in this specification, those skilled in the art can make corresponding adjustments and changes according to the relevant components, as long as they do not deviate from the essence of the invention of this application.

[0031] Preparation Example 1 (E1)

[0032] The silicone rubber having improved surface adhesion of the present invention and a method for preparing the same are described below.

[0033] Step 1) The first rubber mixing step

[0034] 100 parts by weight of a terminal vinyl polysiloxane with a molecular weight of 10,000 to 30,000 and a vinyl content of 0.01-0.03% (mol) (viscosity of 6000 mPa·s to 8000 mPa·s), 10 parts by weight of a side-chain vinyl polysiloxane with a vinyl content of 0.01-0.03% (mol) (viscosity of 500-800 mPa·s), 30 parts by weight of a first white carbon black (300-350 m 2 / g, BET method) and 5 parts by weight of a second white carbon black (100-150 m 2 / g, BET method), 2 parts by weight of 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, 2 parts by weight of 1-ethynyl-1-cyclohexanol, added into a kneader for kneading; after the material is in a solid block, the temperature is raised to 130-140°C, and the kneading is continued for 20 minutes under a pressure of 0.03MPa, and the material is discharged, which is the first mixed rubber;

[0035] Step 2) Second rubber mixing step

[0036] Adding 2 parts by weight of 1-ethynyl-1-cyclohexanol to 100 parts by weight of the first rubber mix, and continuing to mix the rubber in an open mixing mill for 30-40 minutes to obtain a second rubber mix;

[0037] Step 3) The third rubber mixing step

[0038] 1 part by weight of divinyltetramethyldisiloxane platinum complex having a platinum content of 1000 ppm was added to 100 parts by weight of the second mixed rubber, and the mixture was mixed for 1 hour in an inert atmosphere at a pressure of 0.03 MPa to obtain an addition type rubber material.

[0039] Step 4) Vulcanization step

[0040] In 100 parts by weight of addition rubber material, 1 part by weight of divinyltetramethyldisiloxane platinum complex with a platinum content of 2000ppm, 10 parts by weight of hydrogen-containing polysiloxane with a hydrogen content of 10mmol / g and a side chain containing Si-H, 0.5 parts by weight of liquid ammonia, and 2 parts by weight of 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane are added, and vulcanization is carried out at 110°C to 120°C to obtain a silicone rubber product with surface viscosity containing a vulcanization system.

[0041] Comparative Example

[0042] The comparative examples adopt the same preparation process as that of Preparation Example 1, but some components added in each step are adjusted. In order to avoid unnecessary redundancy, only the parts that are different from the preparation examples or embodiments of each comparative example are described below, and the same parts will be omitted from repeated description.

[0043] Comparative Example 1 (C1)

[0044] When adding the first step of white carbon black, 30 parts by weight of the first white carbon black (300-350 parts by weight) 2 / g, BET method) and 5 parts by weight of a second white carbon black (100-150 m 2 / g, BET method) was adjusted to add only 30 parts by weight of 300-350 m / g measured by the BET method. 2 / g of white carbon black, without adding coarse-grained white carbon black material.

[0045] Comparative Example 2 (C2)

[0046] In the sulfurization step of step 4), only 2 parts by weight of 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane was added without using liquid ammonia.

[0047] Comparative Example 3 (C3)

[0048] In the first rubber mixing step of step 1), 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane was not added, and other raw materials were mixed in the same manner as in Preparation Example 1.

[0049] Comparative Example 4 (C4)

[0050] In step 1, instead of the vinyl polysiloxane in Preparation Example 1, 100 parts by weight of a vinyl-terminated polysiloxane having a vinyl content of 0.2-0.4 mol% and a molecular weight of 50,000 to 70,000 (viscosity of 10,000 to 12,000 mPa·s) is selected.

[0051] Comparative Example 5 (C5)

[0052] Compared with Preparation Example 1, Comparative Example 5 no longer performs step 2). In other words, 1-ethynyl-1-cyclohexanol is no longer added in batches, but 1-ethynyl-1-cyclohexanol is used in only one step (step 1).

[0053] Test Case

[0054] For the test results of the rubber compositions obtained in the preparation examples and comparative examples, see Table 2 below.

[0055] Table 2: Relevant performance test results of preparation examples and comparative examples

[0056]

[0057]

[0058] It can be seen from the above comparative experiments that the rubber composition obtained according to Preparation Example 1 has good mechanical properties and electrical resistance characteristics, especially good adhesion to engineering plastics. In the comparative experiment, the inventor unexpectedly found that when only fine-grained silica was used without coarse particles, the elongation at break was deteriorated and the adhesion effect was reduced. The inventor speculates that the coarse-grained silica particles help to fully mix the multi-component rubber raw materials in each step of rubber refining, and act as tiny "grinding balls" in the rubber refining process, making the rubber refining results more sufficient; and in terms of volume resistivity, the coarse silica particles help the rubber composition to further produce an enhanced isolation effect, which is beneficial for the rubber composition to perform dielectric or insulating functions on the surface of the component. When only 2 parts by weight of 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane is added in the vulcanization step without using liquid ammonia (C2), the inventors found that the tensile fracture rate and the degree of hot vulcanization adhesion decreased, which shows that the composite effect of the two components in the vulcanization process is most suitable for the vulcanization process at a lower temperature (such as 115°C), while the process of the single component is insufficiently vulcanized, resulting in insufficient hardness and contact and adhesion performance with plastics. For C3 to C5, it is proved that the order of adding the raw materials of the present invention and the specific batch addition, as well as the parameter selection of the raw materials have an effect on the viscosity and electrical and mechanical properties. For example, when the vinyl content of the original raw rubber component is high (such as 0.2-0.4% (mol) molecular weight), at this time, and the high vinyl content is partially cross-linked to a structure with too many branches, resulting in insufficient hardness, and the corresponding adhesion to the plastic is also reduced. When the inhibitory component 1-ethynyl-1-cyclohexanol is used only once, the rubber mixing process cannot be well controlled, resulting in uneven colloid components. When the plastic components are adhered in the later vulcanization stage, the vulcanization degree cannot be uniformly and quickly reached, resulting in an increase in the degree of peeling.

[0059] According to the implementation scheme and technical contents recorded in the specification of the present invention, the present invention can at least provide the following technical solutions: Although the present disclosure includes specific embodiments, it is obvious to those skilled in the art that various formal and detailed replacements or changes can be made to these embodiments without departing from the gist and scope of the invention of the present claims and their equivalent technical solutions. The embodiments described herein should be considered to be illustrative only and not for the purpose of limitation. The description of the features and aspects in each embodiment is considered to be applicable to similar features and aspects in other embodiments. Therefore, the scope of the present disclosure should not be limited by the specific description, but by the technical solutions of the claims, and all changes within the scope of the claims and their equivalents are interpreted as being included in the technical solutions of the present disclosure.

Claims

1. A method for preparing silicone rubber with improved surface viscosity, characterized in that: The method comprises the following steps: Step 1) First rubber mixing step Selecting terminal vinyl polysiloxane, side chain vinyl polysiloxane with a viscosity of 500-800 mPa·s, white carbon black, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, and 1-ethynyl-1-cyclohexanol, and kneading them at room temperature; then heating to 100-150° C., and kneading them again under an inert atmosphere to obtain a first mixed rubber, wherein the white carbon black is composed of a first white carbon black and a second white carbon black; Step 2) Second rubber mixing step Adding 1-ethynyl-1-cyclohexanol again to the first rubber mix, and continuing to mix the rubber in an open mixing mill to obtain a second rubber mix; Step 3) The third rubber mixing step Adding a platinum catalyst into the second mixed rubber, and continuing to mix under an inert atmosphere and vacuum conditions to obtain an addition type rubber material; Step 4) Vulcanization step Adding a platinum catalyst, a hydrogen-containing polysiloxane having Si-H in the side chain, liquid ammonia, and 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane to the addition-type rubber material again, and vulcanizing the material at 100-130° C. to obtain a silicone rubber with improved surface viscosity; and The method further comprises the following specific steps: In the step 1), 50-150 parts by weight of a terminal vinyl polysiloxane having a vinyl content of 0.01-0.03% mol and a molecular weight of 10,000 to 30,000, 5-15 parts by weight of a side chain vinyl polysiloxane having a vinyl content of 0.01-0.03% mol, and 10-50 parts by weight of a polysiloxane having a specific surface area of ​​300-350 m2 measured by the BET method are selected. 2 / g of the first white carbon black and 2-10 parts by weight of a specific surface area of ​​100-150 m 2 / g of the second silica, 1-3 parts by weight of 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, and 1-5 parts by weight of 1-ethynyl-1-cyclohexanol are added into a kneader and kneaded; after the material is in a solid block, the temperature is raised to 130-140° C., and the kneading is continued for 20 minutes under an air pressure of 0.01-0.05 MPa, and the material is discharged to obtain the first mixed rubber.

2. The method for preparing silicone rubber with improved surface viscosity according to claim 1, characterized in that: The method further comprises the following specific steps: In the step 2), 0.5-5 parts by weight of 1-ethynyl-1-cyclohexanol are added to 100 parts by weight of the first rubber mix, and the rubber mix is ​​continued in an open mixing mill for 30-60 minutes to obtain a second rubber mix.

3. The method for preparing silicone rubber with improved surface viscosity according to claim 2, characterized in that: The method further comprises the following specific steps: In the step 3), 0.5-2 parts by weight of divinyltetramethyldisiloxane platinum complex having a platinum content of 1000ppm-1500ppm is added to 100 parts by weight of the second mixed rubber, and the mixture is mixed for 1-2 hours in an inert atmosphere at a pressure of 0.01-0.05MPa to obtain the addition rubber material.

4. The method for preparing silicone rubber with improved surface viscosity according to claim 3, characterized in that: The method further comprises the following specific steps: In the step 4), 0.5-2 parts by weight of divinyltetramethyldisiloxane platinum complex having a platinum content of 2000ppm-4000ppm, 5-20 parts by weight of hydrogen-containing polysiloxane having a hydrogen content of 10mmol / g and containing Si-H in the side chain, 0.1-2 parts by weight of liquid ammonia, and 1-5 parts by weight of 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane are added to 100 parts by weight of the addition type rubber material, and vulcanization is carried out at 110°C to 130°C to obtain a silicone rubber product with a surface adhesiveness containing a vulcanization system.

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