KR20130061784A - Heat curable silicone rubber compositions and manufacturing method of the same - Google Patents

Abstract

PURPOSE: A thermosetting type silicon rubber composition is provided to have excellent tensile strength, tear strength, and elongation, and to improve transparency and durability, thereby increasing usage count of a silicon rubber mold. CONSTITUTION: A thermosetting type silicon rubber composition comprises a silicone gum; a reinforcing silica; a processing aid including a first processing aid which includes one or more functional groups in the terminal thereof, selected from a hydroxy group, alkoxy group, and amine group, and a second processing aid which includes a copolymer silanol of siloxane polymers including a hydroxy group in the terminal thereof; and a surface treating agent. The amount of the first processing aid and the second processing aid are respectively 1-10 parts by weight and 1-5 parts by weight, based on 100.0 parts by weight of the silicone gum.

Description

Heat curable silicone rubber compositions and manufacturing method of the same

The present invention relates to a thermosetting silicone rubber composition and a method of manufacturing the same.

Silicone rubber parts can be obtained by using a silicone rubber compound (compound) using an organic peroxide as a curing agent, it is possible to manufacture products of various hardness. Silicone rubber manufactured in this form can be applied to various fields in various shapes and performances.

The silicone rubber composition is largely composed of silicone gum, reinforcing silica, and silicone plasticizer. At this time, if a sufficient amount of silica is not used, the mechanical strength of the silicone rubber is weak, so it is difficult to use as an industrial part, the application of the product may be limited. On the contrary, when silica is used more than necessary, workability and regeneration ability will fall.

In addition to the use of an appropriate level of silica, the utilization of silicone plasticizers is also important. Plasticizers should be used at an appropriate level, too much or too little can reduce the physical properties and work performance of the product.

Therefore, the proper selection and mixing of silica and plasticizer is the most basic matter for preparing a thermosetting silicone rubber composition for extrusion. Accordingly, the mechanical properties and the apparent transparency of the silicone rubber are significantly changed.

The present invention was derived to solve the above-described problems, one side of the present invention has excellent mechanical properties, such as tensile strength, tear strength, elongation, and excellent thermosetting silicone rubber composition for extrusion and its excellent transparency It is an object to provide a manufacturing method.

Thermosetting silicone rubber composition according to one aspect of the invention is a silicon gum; Reinforcing silica; Copolymer silanol of a first processing aid comprising a polyorganosiloxane polymer having at least one functional group selected from the group consisting of a hydroxyl group, an alkoxy group, and an amine group, and a siloxane polymer having a hydroxyl group at the terminal; A processing aid comprising a second processing aid comprising; And a surface treating agent.

In this case, the first processing preparation is a substance selected from the group consisting of a dimethylsilicone polymer having a hydroxyl group at both ends, a methylvinylsilicone polymer, a dimethylsilicone polymer having an alkoxy group at the sock end, and a dimethylsilicone polymer having an amino group at the sock end. It is preferable that it consists of.

In addition, the second processing aid preferably consists of dimethylsiloxane-vinylmethylsiloxane copolymer silanol.

In addition, the first processing aid is preferably included in 1 to 10 parts by weight based on 100 parts by weight of silicone gum.

In addition, the second processing aid is preferably included in 1 to 5 parts by weight based on 100 parts by weight of silicone gum.

The reinforcing silica may be included in an amount of 10 to 100 parts by weight, 2 to 20 parts by weight, and 0.1 to 10 parts by weight of the surface treatment agent.

In addition, the surface treatment agent is preferably a reactive silazane having a chemical formula such as the following formula (1).

(Formula 1)

Wherein R 10, R 11, and R 12 are each independently a saturated or unsaturated aliphatic hydrocarbon group or an alkoxy group, wherein the saturated or unsaturated aliphatic hydrocarbon group has 1 to 15 carbon atoms and the alkoxy group has 1 to 10 carbon atoms)

Meanwhile, the silicon gum has a polymerization degree of 5,000 to 10,000, a molecular weight of 400,000 to 700,000, a viscosity of 10,000,000 centipoise (cPs) to 50,000,000 centipoise at 25 ° C., and is represented by RaSiO (4-a) / 2. It is preferable to have a repeating unit.

In addition, the reinforcing silica is a fumed silica having a BET surface area of 200 ~ 300m2 / g, an average particle size of 7 to 20 nm, specific gravity of 1.9 to 2.2 g / cm 3 It can be preferably used.

According to another aspect of the present invention, a method of manufacturing a thermosetting silicone rubber composition includes: providing a silicon gum to a kneader; The silicone gum comprises a reinforcing silica, a first processing aid comprising a polyorganosiloxane polymer having at least one functional group selected from the group consisting of a hydroxyl group, an alkoxy group, and an amine group, and a hydroxyl group at the terminal. A mixing step of mixing by adding a processing aid comprising a second processing aid comprising a copolymer silanol of siloxane polymers; A dispersion step of stirring and dispersing the mixture of the mixing step; And a heating step of heating the mixture after the dispersing step and heating the mixture for 2 to 3 hours.

Thermosetting silicone rubber composition according to an aspect of the present invention has excellent tensile strength, tear strength, as well as elongation is improved compared to the conventional, at the same time has the effect of improving the transparency of the appearance, and significantly improved durability compared to the conventional silicone rubber Increase the number of repeated use of the template.

In addition, the method of manufacturing a thermosetting silicone rubber composition according to another aspect of the present invention has an effect of producing a composition having excellent mechanical properties and excellent transparency by applying a process time extension, dispersion manufacturing process technology applied.

Before describing the present invention in detail, it is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention, which is defined solely by the appended claims. shall. All technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise stated.

Throughout the description and claims, unless the context requires otherwise, the word "comprise" is intended to include the stated article, step or group of articles, and steps; It is not meant to exclude an object, step or group of objects or a group of steps.

On the contrary, the various embodiments of the present invention can be combined with any other embodiments as long as there is no clear counterpoint. In particular, any feature that is indicated to be advantageous or advantageous may be combined with any other feature or feature that is indicated to be advantageous or advantageous.

The thermosetting silicone rubber composition according to one embodiment of the present invention includes a silicon gum, reinforcing silica, a silicon processing aid, and a surface treatment agent.

Composition

1.silicone gum

The polyorganosiloxane silicon gum in this example, preferably has a polymerization degree of 5,000 to 10,000, a molecular weight of 400,000 to 700,000, a viscosity at 25 ° C. of 10,000,000 centipoise (cPs) to 50,000,000 cPs, and a RaSiO (4 It has a repeating unit represented by -a) / 2.

Specifically, dimethylsilium gum, methylphenylvinylsilicon gum, methylvinylsilicon gum, fluorinesilicon gum and the like can be used, and most preferably methylvinylsilicon gum is used.

2. Reinforcing silica

As the reinforcing silica, fumed silica having a BET surface area of 200 to 300 m 2 / g is used. Specifically, the average particle size is 7 to 20 nm, and the specific gravity is 1.9 to 2.2 g / cm 3. Is used.

The fumed silica is preferably 10 to 50 parts by weight based on 100 parts by weight of polyorganosiloxane silicon gum.

If the amount of the fumed silica is less than 10 parts by weight, the overall mechanical properties are easily lowered. If the amount of the fumed silica is more than 100 parts by weight, the even dispersion of the fumed silica becomes difficult, resulting in deterioration of mechanical properties.

The higher the BET surface area of the silica, the higher the surface area or the higher the amount of silica used.

3. Processing aid

Processing aids are applied to the silicone-based plasticizer having a functional group at the end and can be expected to improve the surface treatment and dispersibility of silica, improve the flow of rubber and prevent solidification, and improve mechanical properties.

That is, by applying a silicon processing aid to increase the level of removal of hydroxyl groups (OH-group) present on the surface of the silica, the fumed silica is mixed with the silicon gum and the silica is dispersed well through the stirring process, thereby the silicon Improve the transparency and mechanical properties of rubber.

In the present invention, the processing aid is a first processing aid comprising a polyorganosiloxane polymer having at least one functional group selected from the group consisting of a hydroxyl group, an alkoxy group, and an amine group, and a siloxane polymer comprising a hydroxyl group at the terminal. A second processing aid comprising copolymer silanol of these is used simultaneously.

As the first processing aid, dimethylsilicone polymers having hydroxyl groups at both ends, methylvinylsilicone polymers, dimethylsilicone polymers having an alkoxy group at the sock end, and dimethylsilicone polymers having an amino group at the sock end may be used.

As the second processing aid, dimethylsiloxane-vinylmethylsiloxane copolymer silanol and the like can be used.

The first processing aid may use 1 to 10 parts by weight based on 100 parts by weight of silicone gum, and the second processing aid may use 1 to 10 parts by weight based on 100 parts by weight of silicone gum.

In addition, it is preferable to use 2-20 weight part of silicone processing aids with respect to 100 weight part of silicone gums as a whole processing aid. If it is less than 2 parts by weight, it is difficult to treat and disperse the fumed silica, and it is difficult to express mechanical properties. In addition, the solidification of the rubber is easy to proceed and the flow of the rubber is not easy to use. On the contrary, when the amount is excessively used in excess of 20 parts by weight, the strength of the rubber dough is not easy to handle, and the rubber surface is sticky, which makes it difficult to roll.

4. Surface Treatment

Surface treatments can help to improve the properties of the product and there are no particular restrictions on the amount used. However, in consideration of the amount of reinforcing silica, workability of the silicone rubber composition, and the like, it is preferable to determine the polyorganosiloxane silicone gum in the range of 0.1 to 10 parts by weight.

In addition, in consideration of the linkage with the content of the silicon processing aid, the total content of the silane-based surface treatment agent and the silicon processing aid is determined between 100 parts by weight and about 20 parts by weight of the polyorganosiloxane silicone gum. It is more preferable for expressing mechanical properties and transparent appearance, and is advantageous for ensuring easy workability.

As an example of the surface treating agent, the reactive silazane has a chemical structure such as Chemical Formula 1 below.

Wherein R 10, R 11, and R 12 are each independently a saturated or unsaturated aliphatic hydrocarbon group or an alkoxy group, wherein the saturated or unsaturated aliphatic hydrocarbon group has 1 to 15 carbon atoms and the alkoxy group has 1 to 10 carbon atoms)

5. Other additives

The silicone rubber composition of the present invention may be added with various additives and property enhancers, etc., as necessary, in addition to the above-described materials, and representative examples thereof include a heat resistance improver, a flame retardant improver, and an antipolymerization inhibitor.

As the heat resistance improving agent, metal oxides or metal organic salts of transition metals are used. Examples thereof include iron, nickel, copper, cerium, and titanium oxides and organic acid salts. The heat resistance improver plays a role of preventing oxidation of organic groups in the silicone rubber composition, preventing crosslinking between polymers, and cutting of proper circumference, such as specific characteristics of rubber during specific heat treatment such as specific gravity, hardness, tensile strength and elongation. It helps to change the mechanical properties as little as possible.

As a flame retardant improver, a small amount of platinum compound may be added, unlike the flame retardancy of general organic rubber. This is known because the platinum compound resins the silicone rubber composition.

In this case, an additional flame retardant additive may be applied to secure sufficient flame retardancy, and examples thereof include iron oxide, titanium oxide, rare earth metal compounds, and phosphorus compounds.

In addition, the silicone rubber composition exhibits a depolymerization phenomenon in which curing is returned in a high temperature sealed state, and a depolymerization inhibitor is used to compensate for this, and oxygen acceptors such as CaO, MgO, and ZnO may be used. These materials can improve the depolymerization by neutralizing the organic acid generated as the organic peroxide is decomposed and adjusting the pH of the silicone rubber composition.

Method of Making Silicone Rubber Composition

The method for producing a silicone rubber composition according to the present invention includes a silicon gum providing step, mixing step, dispersion step and heating step.

The silicon gum providing step is a step of adding a silicon gum to the kneader, the mixing step is a step of mixing the reinforcing silica, processing aid and the silicon gum, the dispersing step is a step of stirring and dispersing the above-described mixture, heating step Is a step of heating the mixture by heating after the dispersion step.

Example

Example  One

The composition added to the formulation was added 100 parts by weight of polyorganosiloxane silicone gum to the kneader, and then 50 parts by weight of fumed silica having a BET surface area of 300 m2 / g and a sock end hydroxyl dimethyl silicone polymer (polymerization degree of 5 to 100 parts by weight of the silicone gum). 15) 10 parts by weight of 3 parts by weight of dimethylsiloxane-vinylmethylsiloxane copolymer silanol was added to a kneader, and mixed, stirred, dispersed, heated, heated and cooled to obtain a silicone rubber composition. At this time, the heating step after the temperature increase was 3 hours.

Example 2

A silicone rubber composition was obtained in the same manner as in Example 1 except that 5 g of dimethylsiloxane-vinylmethylsiloxane copolymer silanol was used.

Example 3

A silicone rubber composition was obtained in the same manner as in Example 1 except that 7 g of dimethylsiloxane-vinylmethylsiloxane copolymer silanol was used.

Comparative example  One

A silicone rubber composition was obtained in the same manner as in Example 1 except that dimethylsiloxane-vinylmethylsiloxane copolymer silanol was not used.

Examples 1 to 3 and Comparative Example 1 are collectively shown in Table 1.

Example 1 Example 2 Example 3 Comparative Example 1 Methyl Vinyl Silicone Gum 100 100 100 100 BET 300m2 / g fumed silica 50 50 50 50 Socks-short hydroxyl
Dimethyl Silicone Polymer Polymerization Degree 5 ~ 10 10 10 10 10 Dimethylsiloxane-Vinylmethylsiloxane Copolymersilanol 3 5 7 0 Heating process time 3 3 3 3 2,5-dimethyl-2,5- (t-buthylperoxy) hexane 45% Whole rubber
0.5phr Whole rubber
0.5phr Whole rubber
0.5phr Whole rubber
0.5phr

Experimental Example  One

After fully plasticizing each of the uncured silicone rubber compounds prepared in Examples and Comparative Examples using a two roll mill, 100 parts by weight of the uncured silicone rubber composition was added to 0.5 parts by weight of organic peroxide (2,5- Dimethyl-2,5-t-butylperoxy hexane 45%) was added to disperse sufficiently. After that, the rubber preform sheet was compression molded in a molding mold at 170 ° C. for 10 minutes to make a 2 mm thick test piece, followed by curing at 200 ° C. for 4 hours in a hot air circulation oven to remove unreacted low molecular materials and unreacted organic peroxide. Stabilizing the physical properties of the product to obtain the mechanical properties shown in Table 2 below.

Example 1 Example 2 Example 3 Comparative Example 1 importance 1.19 1.19 1.19 1.19 Plasticity 280 270 250 280 Hardness 73 74 74 71 Tensile Strength (MPa) 11.0 11.0 11.0 11.0 Elongation (%) 500 480 440 400 Tear strength (N / mm) 32 36 30 30 Flowability Good flow Good flow Good flow Poor flow Extruding test Good Good Good Good Hazy 25 23 23 28 Roll workability Good Good Good Good

Example  4

A silicone rubber composition was obtained in the same manner as in Example 2 except that 0.5 g of hexadimethylsilazane, a silica surface treatment agent, was applied.

Example  5

A rubber composition was obtained in the same manner as in Example 4, except that the silicone rubber was manufactured by reducing the heating process time from 3 hours to 2 hours.

Example 4 and Example 5 are collectively shown in Table 3.

Example 4 Example 5 Methyl Vinyl Silicone Gum 100 100 BET 300m2 / g fumed silica 50 50 Socks End Hydroxyl
Dimethyl Silicone Polymer Polymerization Degree 5 ~ 10 10 10 Dimethylsiloxane-Vinylmethylsiloxane Copolymersilanol 5 5 Hexamethyldisilazane 0.5 0.5 Heating process time 3 2 2,5-dimethyl-2,5- (t-buthylperoxy) hexane 45% Whole rubber
0.5phr Whole rubber
0.5phr

Experimental Example  2

After fully plasticizing each of the uncured silicone rubber compounds prepared in Examples 4 and 5 by using a two roll mill, 0.5 parts by weight of organic peroxide (2,5) based on 100 parts by weight of the uncured silicone rubber composition -Dimethyl-2,5-t-butylperoxy hexane 45%) was added to disperse sufficiently. After that, the rubber preform sheet was compression molded in a molding mold at 170 ° C. for 10 minutes to make a 2 mm thick test piece, and then cured in a hot air circulation oven for 4 hours at 200 ° C. for unreacted low molecular weight material and unreacted organic peroxide. By removing the stabilization of the physical properties of the product to obtain the mechanical properties as shown in Table 4.

Example 4 Example 5 importance 1.19 1.19 Plasticity 260 275 Hardness 72 74 Tensile Strength (MPa) 11.5 11.0 Elongation (%) 520 440 Tear strength (N / mm) 38 36 Flowability Good flow Good flow Extruding test Good Good Hazy 21 25 Roll workability Good Good

According to this, when hexamethyldisilazane was used as the surface treatment agent in Example 4, plasticity, elongation, tear strength, transparency, etc. can be confirmed to be more improved than Example 2, and as confirmed in Example 5, heating If the time is reduced, the physical properties are lowered, it can be seen that it is effective to properly control the heating time.

In the above description of the thermosetting silicone rubber composition according to the embodiment of the present invention, the present invention is not limited to the above-described embodiments, and those skilled in the art to which the present invention pertains should not depart from the concept of the present invention. Modifications are possible without departing from the scope of the invention.

The scope of the present invention is defined by the following claims, and is not limited to the description of the specification, and all variations and modifications falling within the scope of the claims are included in the scope of the present invention.

Claims (10)

Silicon gum;
Reinforcing silica;
Copolymer silanol of a first processing aid comprising a polyorganosiloxane polymer having at least one functional group selected from the group consisting of a hydroxyl group, an alkoxy group, and an amine group, and a siloxane polymer having a hydroxyl group at the terminal; A processing aid comprising a second processing aid comprising; And
Thermosetting silicone rubber composition comprising a surface treatment agent. The method of claim 1,
The first processing preparation is a thermosetting material consisting of a material selected from the group consisting of a dimethylsilicone polymer having a hydroxyl group at both ends, a methylvinylsilicone polymer, a dimethylsilicone polymer having an alkoxy group at the sock end, and a dimethylsilicone polymer having an amino group at the sock end. Silicone rubber compositions. The method of claim 1,
The second processing aid is a thermosetting silicone rubber composition consisting of dimethylsiloxane-vinylmethylsiloxane copolymer silanol. The method of claim 1,
The first processing aid is a thermosetting silicone rubber composition is contained in 1 to 10 parts by weight based on 100 parts by weight of the silicone gum. The method of claim 1,
The second processing aid is a thermosetting silicone rubber composition is contained in 1 to 5 parts by weight based on 100 parts by weight of silicon gum. The method of claim 1,
A thermosetting silicone rubber composition comprising 10 to 100 parts by weight of the reinforcing silica, 2 to 20 parts by weight, and 0.1 to 10 parts by weight of the surface treating agent, based on 100 parts by weight of the silicon gum. The method of claim 1,
The surface treatment agent is a thermosetting silicone rubber composition which is a reactive silazane having the chemical formula as shown below.
(Formula 1)

Wherein R 10, R 11, and R 12 are each independently a saturated or unsaturated aliphatic hydrocarbon group or an alkoxy group, wherein the saturated or unsaturated aliphatic hydrocarbon group has 1 to 15 carbon atoms and the alkoxy group has 1 to 10 carbon atoms)
The method of claim 1,
The silicon gum has a polymerization degree of 5,000 to 10,000, a molecular weight of 400,000 to 700,000, a viscosity of 10,000,000 centipoise (cPs) to 50,000,000 centipoise at 25 ° C., and a repeating unit represented by RaSiO (4-a) / 2. Thermosetting silicone rubber composition having a. The method of claim 1,
The reinforcing silica is fumed silica having a BET surface area of 200 to 300 m 2 / g, an average particle size of 7 to 20 nm, and a specific gravity of 1.9 to 2.2 g / cm 3. Providing a silicon gum injecting the silicon gum into the kneader;
The silicone gum comprises a reinforcing silica, a first processing aid comprising a polyorganosiloxane polymer having at least one functional group selected from the group consisting of a hydroxyl group, an alkoxy group, and an amine group, and a hydroxyl group at the terminal. A mixing step of mixing by adding a processing aid comprising a second processing aid comprising a copolymer silanol of siloxane polymers;
A dispersion step of stirring and dispersing the mixture of the mixing step; And
Method of producing a thermosetting silicone rubber composition comprising a heating step of heating the mixture for 2 to 3 hours after the dispersion step.