KR20180053110A - Silicone rubber composition - Google Patents

Abstract

The present invention relates to a silicone rubber composition. According to an embodiment of the present invention, the silicone rubber composition comprises first poly organo siloxane, second poly organo siloxane, and silica. According to the present invention, the silicone rubber composition can maintain excellent durability and mechanical strength.

Description

[0001] SILICONE RUBBER COMPOSITION [0002]

The present invention relates to a silicone rubber composition used as a coating material in the manufacture of cables.

Silicone rubber, which is generally excellent in physical properties such as releasability, water repellency, heat resistance, weather resistance, and insulation, is expanding its application range in order to satisfy flame resistance and environment friendliness of electric and electronic products, which are increasingly regulated.

Such a silicone rubber is converted into a siloxane compound (for example, dimethylcyclosiloxane), which is a main component of the fire during the fire, and undergoes a process of forming an anti-fire film, thereby ensuring flame retardancy. The siloxane compound is structurally weak Therefore, the mechanical strength and durability of the silicone rubber after the fire are lowered.

Further, a platinum-based compound is added to the silicone rubber in order to improve the flame retardancy of the silicone rubber. However, the price of the platinum-based compound is high and the price of the silicone rubber is increased. At this time, a technique has been proposed in which a low-cost flame retardant (for example, carbon black, iron oxide, titanium oxide, aluminum oxide, aluminum hydroxide, magnesium hydroxide, etc.) is used together to reduce the amount of the platinum- The insulation of the rubber, the mechanical strength and the like are deteriorated.

Korean Patent Laid-Open Publication No. 2013-0001591

The present invention provides a silicone rubber composition which is excellent in flame retardancy and can be kept excellent in insulation, durability, and mechanical strength even after fire.

A first polyorganosiloxane having an alkenyl group bonded to at least one of the terminal or side chain of the molecule; A second polyorganosiloxane having an aryl group bonded to the side chain of the molecule; And silica, wherein the content of the second polyorganosiloxane is 0.01 to 5 parts by weight based on the first polyorganosiloxane.

Since the silicone rubber composition of the present invention contains the second polyorganosiloxane having strong intermolecular bonding, the cured product formed by using the second polyorganosiloxane has excellent flame retardancy and can maintain durability and mechanical strength even when exposed to high temperature. Therefore, when the silicone composition of the present invention is used in the manufacture of electrical and electronic products (for example, in the manufacture of cables), the flame retardancy, insulation, durability, mechanical strength and the like of electrical and electronic products can be improved.

Hereinafter, the present invention will be described.

The present invention relates to a silicone rubber composition characterized by containing a second polyorganosiloxane having a strong intermolecular bond in a specific amount range. Such a silicone rubber composition of the present invention comprises a first polyorganosiloxane, a second polyorganosiloxane and silica.

The first polyorganosiloxane is a main component of the silicone rubber composition, and an alkenyl group is bonded to at least one of the terminal or side chain of the molecule. Such a first polyorganosiloxane imparts flexibility, insulation, durability, etc. to a cured product (which means a cured product of the silicone rubber composition of the present invention). The alkenyl group is bonded to Si present in the first polyorganosiloxane, and the bonding ratio thereof may be 0.01 to 9 mol%, specifically 0.04 to 0.2 mol%. Specific examples of the alkenyl group include a vinyl group, a propynyl group, a butynyl group, a pentynyl group, a hexynyl group, an octynyl group, a decynyl group, a hexadecynyl group, and an octadecynyl group.

Such a first polyorganosiloxane may be embodied as a compound represented by the following general formula (1).

[Chemical Formula 1]

In Formula 1,

R ₁ , R ₆ and R ₁₀ are the same or different and each independently represents a C ₂ to C ₁₈ alkenyl group (specifically, a vinyl group)

R ₂ , R ₃ , R ₄ , R ₅ , R ₇ , R ₈ and R ₉ are the same or different and each independently represents a C ₁ to C ₁₀ alkyl group (specifically, a methyl group)

m is an integer of 1 to 25, and n is an integer of 1 to 25. [

The second polyorganosiloxane has at least one aryl group bonded to the side chain of the molecule. Since the second polyorganosiloxane has an aryl group bonded thereto and the bonding between the molecules is strong, the present invention can improve the flame retardancy, durability, and the like of the cured product.

Specifically, a polyorganosiloxane to which an alkyl group is bonded to a side chain of a molecule is converted (decomposed) into a siloxane compound such as dimethylcyclosiloxane when exposed to a high temperature (or in case of fire). The dimethylcyclosiloxane is weak The flame retardancy of water, durability, mechanical strength, and the like are reduced.

However, the present invention prevents the cured product from being converted into dimethylcyclosiloxane even when the cured product is exposed to a high temperature by introducing the second polyorganosiloxane having strong intermolecular bonding into the silicone rubber composition, thereby improving the flame retardancy, durability, have.

In particular, the silicone rubber composition of the present invention can improve the flame retardancy, durability and mechanical strength of the cured product by including the second polyorganosiloxane in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the first polyorganosiloxane.

The aryl group is bonded to Si present in the second polyorganosiloxane, and the bonding ratio thereof may be 1.3 to 91 mol%, specifically 15 to 60 mol%. Specific examples of the aryl group include a phenyl group, a naphthyl group, a fluorenyl group, and an anthracenyl group.

Such a second polyorganosiloxane may be embodied as a compound represented by the following general formula (2).

(2)

In Formula 2,

R _a and R _j are the same or different and are each independently a C ₁ to C ₁₀ alkyl group,

R _b , R _c , R _d , R _e , R _f , R _g , R _h and R _i are the same or different and each independently represents a C ₁ to C ₁₀ alkyl group and a C ₆ to C ₁₈ aryl group ≪ / RTI >

x is an integer of 1 to 7, and y is an integer of 10 to 22.

The silica imparts mechanical strength to the cured product. Such silica may be fumed silica or precipitated silica. The silica may have a specific surface area of 100 to 400 m < 2 > / g as measured by the BET method.

Such silica may be included in the silicone rubber composition in an amount of 10 to 60 parts by weight based on 100 parts by weight of the first polyorganosiloxane. If the amount of the silica is less than 10 parts by weight, it may be difficult to secure the mechanical strength of the cured product. If the amount of the silica is more than 60 parts by weight, the workability and moldability of the cured product may be deteriorated.

Meanwhile, the silica may be surface-treated with a third polyorganosiloxane having a hydroxyl group (OH) bonded to the end of the molecule to improve dispersibility of the silicone rubber composition. Specifically, the third polyorganosiloxane is a polyorganosiloxane having a hydroxyl group at both ends of the molecule and an alkyl group (specifically, a methyl group) bonded to the side chain of the molecule, a polyorganosiloxane having a hydroxyl group at both ends of the molecule, (Specifically, a methyl group) and an alkenyl group (specifically, a vinyl group); a polyorganosiloxane having a hydroxyl group and an alkenyl group (specifically, a vinyl group) bonded to both ends of the molecule; Lt; / RTI >

Wherein the third polyorganosiloxane may be included in the silicone rubber composition in an amount of 2 to 40 parts by weight based on 100 parts by weight of the first polyorganosiloxane. If the content of the third polyorganosiloxane is less than 2 parts by weight, the dispersibility of the silica may be lowered. If the content of the third polyorganosiloxane is more than 40 parts by weight, the workability may be lowered due to the low viscosity of the silicone rubber composition.

The silicone rubber composition of the present invention may further contain a filler, a platinum compound, or a metal oxide in order to further improve the flame retardance, durability, and mechanical strength of the cured product.

The filler is for increasing the flame retardancy and mechanical strength of the cured product and may include at least one selected from the group consisting of quartz, mica, talc, vermiculite, bentonite and smectite.

The mica, vermiculite, and bentonite are natural minerals and have a property of expanding at high temperatures. When such a cured product is exposed to high temperatures, layer porosity is formed in the process of forming a non-burned coating, so that the durability (or internal protection) of the cured product can be increased. Also, the layered voids have high marginal fracture strength even when force is applied perpendicularly on the plate surface, so that the mechanical strength can be maintained even after the cured product is exposed to high temperatures. When such mica, vermiculite, or bentonite is contained as a filler, the content thereof may be 1 to 20 parts by weight based on 100 parts by weight of the first polyorganosiloxane. If the content of the above components is out of the above range, the durability and mechanical strength of the cured product may be lowered.

The quartz contributes to the formation of a fire-retardant film when the cured product is exposed to high temperatures, thereby improving the flame retardancy of the cured product. Such quartz has a low unit cost as compared with the amount used, so that the economical efficiency of the silicone rubber composition can be improved while improving the flame retardancy of the cured product. When such quartz is included as the filler, the content thereof may be 1 to 50 parts by weight based on 100 parts by weight of the first polyorganosiloxane. If the content of the quartz exceeds the above range, the flame retardancy of the cured product, the economical efficiency of the silicone composition, and the like may be lowered.

The platinum-based compound induces a high-density crosslinked structure when the cured product is exposed to high temperatures, thereby forming a fire-retardant film, thereby improving the flame retardancy of the cured product. The content of such a platinum-based compound may be 1 part by weight or less (specifically, 1 to 1000 ppm) relative to 100 parts by weight of the first polyorganosiloxane. If the content of the platinum-based compound is out of the above range, the flame retardancy of the cured product may be lowered.

The metal oxide prevents the cured product from forming blooming, and may include at least one selected from the group consisting of magnesium oxide, calcium oxide, and barium oxide. Specifically, when only the primary curing is performed in the course of curing the silicone rubber composition, a degenerated product having a carboxyl group is formed on the surface of the cured product and blooming phenomenon appears on the surface of the cured product. The metal oxide comes into contact with moisture in the air, So that the blooming phenomenon is prevented from occurring due to neutralization. The content of the metal oxide may be 0.01 to 5 parts by weight based on 100 parts by weight of the first polyorganosiloxane. If the content of the metal oxide is out of the above range, the effect of preventing blooming of the cured product may be deteriorated.

The silicone rubber composition of the present invention reacts with a vulcanizing agent such as an organic peroxide to finally obtain a cured cured product (rubber product). Examples of the organic peroxide include alkyl-based organic peroxides and acyl-based organic peroxides. Examples of the alkyl-based organic peroxide include 2,5-dimethyl-2,5-di (t-butylperoxy) hexane or dicumyl peroxide. Examples of the acyl organic peroxide include bis-2,4-dichlorobenzoyl Peroxide, benzoyl peroxide and the like, and they may be mixed and used. The amount of the organic peroxide to be used may be 0.5 to 5 parts by weight based on 100 parts by weight of the first polyorganosiloxane.

The cured product formed from the silicone rubber composition of the present invention described above is basically excellent in heat resistance, insulation, durability and the like. Also, since the silicone rubber composition of the present invention is excellent in flame retardancy when the cured product is exposed to high temperatures and maintains excellent mechanical strength and durability even after exposure to high temperatures, A coating material in manufacturing).

Hereinafter, the present invention will be described in detail with reference to examples. However, the following examples are illustrative of the present invention, and the present invention is not limited by the following examples.

[ Example  One]

The first polyorganosiloxane was put into a kneader, premixed, and mixed with silica (specific surface area: 207 m 2 / g) and a third polyorganosiloxane to mix and disperse. Then, a second polyorganosiloxane, a filler, a platinum compound, and a metal oxide were added and stirred and dispersed at 50 to 90 for 20 minutes to 1 hour to prepare a silicone rubber composition. The composition of each component used is shown in Table 1 below (content unit: parts by weight).

[ Example  2 to 7]

The silicone rubber composition was prepared in the same manner as in Example 1 except that the composition shown in Table 1 was used.

[ Comparative Example  1 to 4]

The silicone rubber composition was prepared in the same manner as in Example 1 except that the composition shown in Table 2 was used.

ingredient Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 The first poly
Ogano
Siloxane VINYL SILICONE GUM
(vinyl content: 0.06 to 0.08 mol% 100 100 100 100 100 100 100 The second poly
Ogano
Siloxane TRIMETHYL TERMINATED DIMETHYL DIPHENYL POLYSILOXANE COPOLYMER
(phenyl content: 25 mol%) 0.01 0.1 0.2 0.5 One 3 5 Silica Specific surface area: 300 m < 2 > / g 51.07 51.07 51.07 51.07 51.07 51.07 51.07 The third poly
Ogano
Siloxane SILANOL TERMINATED POLYDIMETHYSILOXANE
(OH content: 5.1 to 6.0 mol%) 10.30 10.30 10.30 10.30 10.30 10.30 10.30 HYDROXY TERMINATED DIMETHYL-METHYLVINYL POLYSILOXANE COPOLYMER
(OH content: 4.0 to 5.0 mol%
vinyl content: 6.5 to 7.5 mol%) 5.10 5.10 5.10 5.10 5.10 5.10 5.10 Filler quartz 28.30 28.30 28.30 28.30 28.30 28.30 28.30 mica 8.37 8.37 8.37 8.37 8.37 8.37 8.37 Platinum-based compound Platinum-1,3-divinyltetramethyldisiloxane complex 0.08 0.08 0.08 0.08 0.08 0.08 0.08 metal
oxide Magnesium oxide 0.49 0.49 0.49 0.49 0.49 0.49 0.49 Organic peroxide 2,4-Dichlorobenzoyl Peroxide (45% paste) 3.06 3.06 3.06 3.06 3.07 3.10 3.13

ingredient Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 The first poly
Ogano
Siloxane VINYL SILICONE GUM
(vinyl content: 0.06 to 0.08 mol% 100 100 100 100 The second poly
Ogano
Siloxane TRIMETHYL TERMINATED DIMETHYL DIPHENYL POLYSILOXANE COPOLYMER
(phenyl content: 25 mol%) - 0.001 0.005 6 Silica Specific surface area: 300 m < 2 > / g 51.07 51.07 51.07 51.07 The third poly
Ogano
Siloxane SILANOL TERMINATED POLYDIMETHYSILOXANE
(OH content: 5.1 to 6.0 mol%) 10.30 10.30 10.30 10.30 HYDROXY TERMINATED DIMETHYL-METHYLVINYL POLYSILOXANE COPOLYMER
(OH content: 4.0 to 5.0 mol%
vinyl content: 6.5 to 7.5 mol%) 5.10 5.10 5.10 5.10 Filler quartz 28.30 28.30 28.30 28.30 mica 8.37 8.37 8.37 8.37 Platinum-based compound Platinum-1,3-divinyltetramethyldisiloxane complex 0.08 0.08 0.08 0.08 metal
oxide Magnesium oxide 0.49 0.49 0.49 0.49 Organic peroxide 2,4-Dichlorobenzoyl Peroxide (45% paste) 3.06 3.06 3.06 3.15

[ Manufacturing example  1 to 7 and Comparative Manufacturing Example  1 to 4]

Each of the silicone rubber compositions was thoroughly plasticized in a twin-roll mill and sufficiently dispersed by adding a 50% paste of organic peroxide (bis-2,4-dichlorobenzoyl peroxide) (see Table 1 and 2 above). Then, a defoaming preform was put into a molding mold and molded at 120 DEG C for 5 minutes to produce a cured product having a thickness of 2 mm.

[ Experimental Example ]

The physical properties of the cured product were evaluated as follows. The results are shown in Tables 3 and 4 below.

1. Plasticity: measured according to ASTM D926.

2. Hardness (Shore A): Measured according to ASTM D2240 (SHORE A).

3. Tensile strength (MPa): Measured according to ASTM D412.

4. Elongation (%): Measured according to ASTM D412.

5. Tear strength (N / mm): Measured according to ASTM D624 (DIE C).

6. Specific gravity: measured according to ASTM D79.

7. Non-burning film formation: The cured product was burned until it self-extinguished by flame heating, and then the formation of a fire-retardant film was judged (the case where the burned cured product does not catch fire when it is heated again is "Quot; and " x ").

8. Blooming: The cured product was exposed to air at room temperature for 24 hours, and visually observed for formation of white powder and crystals on the surface (when the white powder and crystals were observed, the case of covering at least 90% of the surface was referred to as " Quot; indicates that the white powder and the crystal cover less than 60% of the surface and "? &Quot; indicates that the white powder and the crystal cover less than 30% &Quot; x ").

9. Nonflammable film retainability: After fixing the cured product to the clamp holder and heating the flame, it was observed that the cured product was short-circuited by applying impact to the clamp holder or by moving it vertically and horizontally (when the holder was impacted or the cured product was vigorously moved The case where a short circuit does not occur and the case where a short circuit does not occur even if a shock is applied to the holder is sometimes referred to as " ", but a short circuit occurs occasionally when the cured product is vigorously moved, &Quot; DELTA ", and when the cured product was caused to move slowly, the short circuit was judged as " DELTA "

10. Oil bleeding: The cured product was exposed to air at room temperature for 24 hours and then visually observed and the surface was rubbed by hand to compare the bleeding state. (When visually observed, a trace of oil was observed on the surface, and when rubbed by hand ◎ "when it is slippery and" ◎ "and when it is observed with the naked eye, there is a little trace of oil breakage, and when it rubs when rubbed by hand it is" ○ " Quot; DELTA ", and when the oil was not rubbed and the surface was clean, the result was " x ").

Properties Production Example 1 Production Example 2 Production Example 3 Production Example 4 Production Example 5 Production Example 6 Production Example 7 Plasticity 282 279 285 283 275 280 282 Hardness 74 74 74 73 72 71 70 Tensile strength (MPa) 9.2 8.9 9.1 9.3 8.6 8.1 7.6 Elongation (%) 375 382 370 368 357 333 313 Tear strength (N / mm) 29.3 28.1 31.2 29.9 30.7 29.1 29.7 importance 1.32 1.32 1.32 1.32 1.32 1.32 1.32 Nonflammable film formation ◎ ◎ ◎ ◎ ◎ ◎ ◎ Blooming × × × × × × × Nonflammable film retention ○ ◎ ◎ ◎ ◎ ◎ ◎ Oil bleeding × × × × × × △

Properties Comparative Preparation Example 1 Comparative Production Example 2 Comparative Production Example 3 Comparative Production Example 4 Plasticity 285 284 286 279 Hardness 74 74 74 70 Tensile strength (MPa) 9.2 9.1 9.1 7.3 Elongation (%) 371 374 373 298 Tear strength (N / mm) 30.9 31.1 30.7 29.3 importance 1.32 1.32 1.32 1.32 Nonflammable film formation ◎ ◎ ◎ ◎ Blooming × × × × Nonflammable film retention × × × ◎ Oil bleeding × × × ◎

Referring to Tables 3 and 4, it can be seen that the silicone rubber composition of the present invention has excellent flame retardancy and excellent oil bleeding characteristics.

Claims (8)

A first polyorganosiloxane having an alkenyl group bonded to at least one of the terminal or side chain of the molecule;
A second polyorganosiloxane having an aryl group bonded to the side chain of the molecule; And
Silica,
Wherein the content of the second polyorganosiloxane is 0.01 to 5 parts by weight based on the first polyorganosiloxane. The method according to claim 1,
And the proportion of aryl groups bonded to side chains of the molecules of the second polyorganosiloxane is from 1.3 to 91 mol%. The method according to claim 1,
Wherein the first polyorganosiloxane is a compound represented by the following formula (1).
[Chemical Formula 1]

In Formula 1,
R ₁ , R ₆ , and R ₁₀ are the same or different and are each independently a C ₂ to C ₁₈ alkenyl group,
R ₂ , R ₃ , R ₄ , R ₅ , R ₇ , R ₈ and R ₉ are the same or different and are each independently a C ₁ to C ₁₀ alkyl group,
m is an integer from 1 to 25,
and n is an integer of 1 to 25. [ The method according to claim 1,
Wherein the second polyorganosiloxane is a compound represented by the following formula (2).
(2)

In Formula 2,
R _a and R _j are the same or different and are each independently a C ₁ to C ₁₀ alkyl group,
R _b , R _c , R _d , R _e , R _f , R _g , R _h and R _i are the same or different and each independently represents a C ₁ to C ₁₀ alkyl group and a C ₆ to C ₁₈ aryl group ≪ / RTI >
x is an integer of 1 to 7,
and y is an integer of 10 to 22. The method according to claim 1,
Wherein the silica is surface-treated with a third polyorganosiloxane having a hydroxyl group (OH) bonded to the end of the molecule. The method according to claim 1,
Quartz, mica, talc, vermiculite, bentonite, and smectite. The method according to claim 1,
And a platinum-based compound. The method according to claim 1,
Wherein the metal oxide further comprises at least one metal oxide selected from the group consisting of magnesium oxide, calcium oxide, and barium oxide.