CN107189071B

CN107189071B - Preparation method of platinum catalyst for liquid silicone rubber

Info

Publication number: CN107189071B
Application number: CN201710486738.7A
Authority: CN
Inventors: 许静文; 康润华
Original assignee: Jiangsu Csi Material Technology Co ltd
Current assignee: Jiangsu Silicon Age Material Technology Co., Ltd.
Priority date: 2017-06-23
Filing date: 2017-06-23
Publication date: 2021-01-15
Anticipated expiration: 2037-06-23
Also published as: CN107189071A

Abstract

The invention provides a preparation method of a platinum catalyst for liquid silicone rubber, which comprises the following steps: s1, adding sodium bicarbonate into an alcohol solvent for dissolving; s2, under the anaerobic condition, adding chloroplatinic acid, vinyl tetramethyl disiloxane and maleic ester compounds into S1 for reaction; and S3, after the reaction in the S2 is finished, filtering out solids, washing for multiple times, combining the filtrates, and removing low molecules from the filtrates to obtain the platinum catalyst for the liquid silicone rubber. The platinum catalyst for the liquid silicone rubber prepared by the invention is used in the liquid silicone rubber, the addition reaction activity and the rate of vinyl polysiloxane and hydrogen polysiloxane are effectively adjusted, the catalysis rate is excellent, the operable time of addition type silicone rubber and the normal-temperature storage time of single-component addition type liquid silicone rubber are obviously improved, the smoothness and the smoothness of the surface of a cured part after curing are obviously improved, and the platinum catalyst is suitable for single-component or double-component organic silicon adhesives. The preparation method has the advantages of simple operation process and high product yield, and is suitable for industrial popularization and application.

Description

Preparation method of platinum catalyst for liquid silicone rubber

Technical Field

The invention relates to the technical field of catalysts for addition type liquid silicone rubber, and in particular relates to a preparation method of a platinum catalyst for liquid silicone rubber.

Background

Among the catalysts which initiate the addition reaction between Si-Vi (Vi is a shorthand for Vinyl) and Si-H, the most widely used and most effective catalyst is the platinum catalyst. However, if the activity of the platinum catalyst used for the hydrosilylation reaction is too high, the problem that the single-component addition type liquid silicone rubber cannot be stored due to too short operable time after the two-component addition type liquid silicone rubber is mixed exists; if the activity of the catalyst is too low, the completion of the addition reaction cannot be guaranteed. Thus, the ideal catalyst should be such that little reaction occurs until the sulfiding temperature is reached, and once the reaction temperature is reached, the reaction must proceed rapidly.

Karstedt's catalyst is the most commonly used high activity catalyst in platinum catalysts, and inhibitors may be added to the system to avoid the hydrosilylation reaction from proceeding too quickly at room temperature. Alkynol compounds are the most commonly used inhibitors at present, but have the defect of easy volatilization, so when addition type liquid silicone rubber is used, the surface of a cured part is not smooth enough due to vacuum bubble discharge and volatilization of the alkynol during heating curing.

In order to overcome the above disadvantages, patent CN 104371106A discloses a microencapsulated platinum catalyst and a preparation method thereof. The microencapsulated platinum catalyst is prepared by encapsulating a liquid platinum catalyst in a thermoplastic resin with a low softening point, wherein at room temperature or a lower temperature, the platinum catalyst cannot play a role in catalysis because the platinum catalyst is isolated, but when the temperature is increased to be higher than the softening point of the resin, the platinum catalyst encapsulated by the resin can be released, so that hydrosilylation is catalyzed to enable a sizing material to be crosslinked and cured. But the manufacturing process is complex, difficult to industrialize, high in cost and inconvenient to popularize. Patents CN 105255192A and CN 103589157A coordinate divinyltetramethyldisiloxane and acetylene compounds together with platinum to obtain a highly active vinyl platinum complex. The catalyst is applied to addition type liquid silicone rubber, integrates inhibition and catalysis, has two functions by one dosage, has longer storage stability at room temperature, and has faster vulcanization speed under proper heating condition. However, the acetylene compound ligand used in the catalyst has low boiling point, and the formed complex has poor stability, so that the acetylene compound ligand is easy to volatilize and lose in the high-temperature curing process, and the performance and the appearance of the liquid silicon rubber vulcanized by using the catalyst are not ideal.

Disclosure of Invention

The invention provides a preparation method of a platinum catalyst for liquid silicone rubber according to the defects in the prior art.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a preparation method of a platinum catalyst for liquid silicone rubber, which comprises the following steps:

s1, adding sodium bicarbonate into an alcohol solvent for dissolving;

s2, under the anaerobic condition, adding chloroplatinic acid, vinyl tetramethyl disiloxane and maleic ester compounds into S1 for reaction;

s3, after the reaction in the S2 is finished, filtering out solids, washing for multiple times, combining filtrates, and removing low molecules from the filtrates to obtain the platinum catalyst for the liquid silicone rubber;

the maleate compound in S2 was bis-trimethylsilyl maleate or 1.9g bis-vinyldimethylsilyl maleate.

The structure of the maleate compound in S2 is shown as follows:

wherein R is a monofunctional organosilicon end-capping agent of linear chain or branched chain aliphatic hydrocarbon group, substituted or unsubstituted aliphatic cyclic hydrocarbon group, trimethyl silicon or vinyl dimethyl silicon.

More preferably, the maleate-based compound in S2 is bis-trimethylsilyl maleate or bis-vinyldimethylsilyl maleate.

The invention adopts a mode of coordinating divinyl tetramethyl disiloxane and maleic acid ester compounds with platinum to obtain the platinum catalyst with a special structure and both catalytic and inhibitory properties. The additive silicon rubber can effectively inhibit the occurrence of hydrosilylation reaction at normal temperature, so that the operable time of the additive silicon rubber and the normal-temperature storage time of the single-component additive liquid silicon rubber can be obviously improved.

Preferably, the molar ratio of the chloroplatinic acid to the vinyl tetramethyl disiloxane is 1: 3-100; the molar ratio of the maleic ester to the vinyl tetramethyl disiloxane is 1: 1-500.

More preferably, the molar ratio of the chloroplatinic acid to the vinyl tetramethyl disiloxane is 1: 5-50; the molar ratio of the maleic ester to the vinyl tetramethyl disiloxane is 1: 5-100.

Preferably, the oxygen-free condition in S2 is to add nitrogen for the reaction.

Preferably, the temperature of the reaction in S2 is 40 ℃ to 120 ℃.

More preferably, the temperature of the reaction in S2 is 50 ℃ to 90 ℃.

Preferably, the alcohol solution in S1 is one or more of methanol, ethanol, propanol, isopropanol, butanol, or isobutanol.

The invention also protects the platinum catalyst for the liquid silicon rubber prepared by the preparation method.

Further, the application of the platinum catalyst for protecting the liquid silicone rubber in improving the surface smoothness and smoothness of an object after the liquid silicone rubber is vulcanized is disclosed.

Compared with the prior art, the invention has the following advantages and beneficial effects:

the platinum catalyst for the liquid silicone rubber prepared by the invention is used in the liquid silicone rubber, can obviously improve the smoothness of the surface of a cured part after curing, effectively adjusts the activity and the rate of addition reaction of vinyl polysiloxane and hydrogen-based polysiloxane, has excellent catalytic rate, and is suitable for single-component or double-component organic silicon adhesives. The preparation method has the advantages of simple operation process and high product yield, and is suitable for industrial popularization and application.

Detailed Description

The present invention is further illustrated by the following specific examples, which are set forth below to provide some detailed embodiments and specific procedures. The reagents, methods and apparatus employed in the present invention are of the kind commonly employed in the art, unless otherwise specified.

Example 1

The preparation method of the platinum catalyst C1 for the addition type liquid silicone rubber comprises the following steps:

(1) adding 3ml of ethanol solution into a three-necked bottle, starting magnetic stirring, and then adding 3.5g of sodium bicarbonate;

(2) introducing nitrogen for 0.5h, and exhausting air in the reactor;

(3) then 0.3g of chloroplatinic acid, 4g of vinyl tetramethyl disiloxane and 1.7g of bis-trimethylsilyl maleate are added into the reaction bottle, and the mixture is heated to 70 ℃ for continuous reaction;

(4) stopping the reaction when the color of the reactant is changed into light yellow or basically colorless;

(5) filtering to remove solid, and washing solid filter residue with reactant alcohol for multiple times;

(6) and (4) concentrating the filtrate after multiple filtration, and removing low molecules at low temperature and high vacuum to obtain the platinum catalyst.

Example 2

The preparation method of the platinum catalyst C2 for the addition type liquid silicone rubber comprises the following steps:

(1) adding 5ml of ethanol solution into the thickened pressure-resistant single-screw-neck bottle, starting magnetic stirring, and then adding 5g of sodium bicarbonate;

(2) introducing nitrogen for 0.5h, and exhausting air in the reactor;

(3) then 0.6g of chloroplatinic acid, 6g of vinyl tetramethyl disiloxane and 1.9g of bis-vinyl dimethyl silane maleate are added into the reaction bottle, and the mixture is heated to 70 ℃ for continuous reaction;

Example 3

Mixing vinyl resin, vinyl silicone oil and hydrogen-containing silicone oil with different qualities according to an optimized proportion, wherein the proportion of vinyl/hydrogen radical groups is 0.9: 1-1: 0.9, then adding 2ppm of C1 into the basic rubber material, and after uniformly mixing again, inspecting the reactivity of the prepared addition type liquid silicone rubber.

Example 4

The same basic rubber as in example 3 was used, then C2 was added in an amount of 2ppm, and the reactivity of the addition liquid silicone rubber thus prepared was examined after mixing homogeneously.

Comparative example 1

The same basic rubber material as in example 3 was used, then a commercially available karstedt catalyst was added in an amount of 2ppm, and the reactivity of the prepared addition-type liquid silicone rubber was examined after mixing homogeneously.

Comparative example 2

The same basic rubber material as in example 3 was used, then a commercially available karstedt catalyst in an amount of 2ppm and acetylene cyclohexanol in an amount of 200ppm were added, and the reactivity of the formulated addition liquid silicone rubber was investigated after mixing homogeneously.

And (3) effect testing:

the reactivity test is mainly to pass the test of the time for gelation to occur at 80 ℃; the normal temperature operable time is the time when the viscosity increase rate of the sizing material reaches 10 percent at the constant temperature of 25 ℃ through testing; the appearance of the cured article was determined by testing the smoothness and flatness of the surface of the cured article after 3 hours of curing at 150 ℃. The test results are shown in table 1 below:

TABLE 1

	Gelation time	Operational time	Appearance of cured part
				Example 3	10min	240min	Is flat and smooth
Example 4	8.5min	165min	Is flat and smooth
				Comparative example 1	5min	38min	Cracks of tortoise
Comparative example 2	11min	375min	Cracks of tortoise

As can be seen from Table 1, the gelation time of examples 3 and 4 is equivalent to that of comparative examples 1 and 2, but the operable time is significantly longer than that of comparative example 1, after the vinyl platinum complex prepared by the method is prepared into addition type liquid silicone rubber, the viscosity of the liquid silicone rubber at normal temperature is slowly increased, the liquid silicone rubber has enough operable time, and the reaction rate at high temperature is high, the high-temperature reaction activity is high, and the surface of the silicone rubber is smooth and flat after being completely cured, so that the method has obvious advantages compared with the commercially available traditional Karstedt catalyst.

The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A preparation method of a platinum catalyst for liquid silicone rubber is characterized by comprising the following steps:

s1, adding sodium bicarbonate into an alcohol solvent for dissolving;

s3, after the reaction in S2 is finished, filtering out solids, washing for multiple times, combining filtrates, and removing low molecules from the filtrates to obtain the platinum catalyst for the liquid silicone rubber;

the maleate compound in S2 is bis-trimethylsilyl maleate or bis-vinyl dimethylsilyl maleate.

2. The preparation method according to claim 1, wherein the molar ratio of chloroplatinic acid to vinyltetramethyldisiloxane is 1:3 to 100; the molar ratio of the maleate compound to the vinyl tetramethyl disiloxane is 1: 1-1: 500.

3. The production method according to claim 1 or 2, wherein the molar ratio of chloroplatinic acid to vinyltetramethyldisiloxane is 1:5 to 50; the molar ratio of the maleate compounds to the vinyl tetramethyl disiloxane is 1: 5-100.

4. The method according to claim 1, wherein the oxygen-free condition in S2 is to add nitrogen gas for the reaction.

5. The method according to claim 1, wherein the temperature of the reaction in S2 is 40 ℃ to 120 ℃.

6. The method according to claim 1 or 5, wherein the temperature of the reaction in S2 is 50 to 90 ℃.

7. The preparation method according to claim 1, wherein the alcohol solvent in S1 is one or more of methanol, ethanol, propanol or butanol.

8. A platinum catalyst for liquid silicone rubber produced by the production method according to any one of claims 1 to 7.

9. Use of the platinum catalyst for liquid silicone rubber according to claim 8 for improving the surface smoothness and smoothness of an object after vulcanization of the liquid silicone rubber.