JPS5814463B2 - silicone rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a silicone rubber composition that does not adhere to metals.

Silicone rubber has a processing disadvantage in that when press vulcanization is performed, it is often difficult to separate the silicone rubber from the metal mold.

Furthermore, when silicone rubber is brought into contact with metal and cured, the silicone rubber often adheres closely to the metal and becomes difficult to peel off.

For example, in the case of electric wires coated with silicone rubber, the core wire and the rubber stick together, making it difficult to peel off the rubber layer, which may cause problems during construction work.

This core wire adhesion phenomenon is remarkable in mild steel wires as core wires and metal wires obtained by plating tin or the like on the core wires.

A known method for preventing adhesion is to add fatty acid salts of metals such as zinc stearate and calcium stearate to silicone rubber (Japanese Patent Laid-Open No. 49-124).
151 Publication), this method has the disadvantage that because the additive is a solid powder, it has poor dispersibility in the composition, poor workability, and that heat resistance decreases when added in an amount sufficient to prevent adhesion. There is.

The present invention provides a composition which eliminates the above-mentioned drawbacks, provides a sufficient adhesion prevention effect, and has extremely excellent dispersibility of additives for adhesion prevention into the composition.

That is, in the present invention, (5) 1.980 to 2.002 monovalent organic groups bonded to silicon atoms exist per silicon atom, and so (7)
A vinyl group with an average mole ratio of 0.01 to 2 of all organic groups, and at least 2 vinyl groups in the molecule, however, when (C) (1) is used, an average of more than 2 vinyl groups in the molecule. 100 parts by weight of polyorganosiloxane having a degree of polymerization of t,o o o or more (B) Inorganic filler 10~
200 parts by weight, and (C) (1) a catalytic amount of an organic peroxide, or (2) (a) a polyorganohydride diene siloxane having an average number of more than two Si-H bonds in one molecule. A polyorganosiloxane composition comprising 0.1 to 10 parts by weight and a catalytic amount of platinum or a platinum-based compound, A is the same or different alkylene group, Ql is an alkylene group R
3 is a monovalent aliphatic hydrocarbon group having 4 to 30 carbon atoms, n is O
or 1, m represents an integer of 0 or 1 or more, n0m is 1 or more) and an alkylene group, R4 is 1 having 4 to 30 carbon atoms
a monovalent organic group selected from the group consisting of a valent aliphatic hydrocarbon group, where a is 0, 1 or 2, b is 1 or 2, and a+b is 1, 2 or 3). This invention relates to a silicone rubber composition comprising 0.03 to 10 parts by weight of a polyorganosiloxane having at least one siloxy unit per molecule based on component (A).

Components (5) to (C) of the present invention are those used in ordinary silicone rubber compositions.

In general, silicone rubbers are crosslinked by reacting methyl groups and vinyl groups bonded to silicon atoms using an organic peroxide as a catalyst, and silicone rubbers are crosslinked by reacting vinyl groups bonded to silicon atoms and hydrogen atoms with a platinum-based catalyst. There are two types: one in which crosslinking is carried out by addition reaction under these conditions, and either of these may be used in the present invention.

The former corresponds to the combination of (5) and (C)(1) in the components of the present invention, and the latter corresponds to the combination of (A) and (C)(2).

In the latter case, (CX2) (
A) polyorganohydride diene siloxane is essential.

The polyorganosiloxane (A) used in the present invention is a vinyl group-containing polyorganosiloxane and has the general formula R6
-((R7XR8)SiO+SiR7R8R6 is common, but there is some R9Si in the molecule.
It may also contain O3/2 units and/or S s O 2 units.

Here, R7 to R9 are the same or different monovalent organic groups.

It is also permissible for R6 to be a monovalent organic group or a part or all of it to be a hydroxyl group.

Examples of organic groups include alkyl groups such as methyl, ethyl, and furoyl groups, alkenyl groups such as vinyl and allyl groups, aryl groups such as phenyl, chloromethyl, cyanethyl, trifluoropropyl, and trifluorophenyl. Substituted hydrocarbon groups such as Nato are exemplified, but in particular, it is necessary to contain an average of 0.01 to 2 moles of vinyl groups,
In addition, in order to crosslink (vulcanize) and form a netted structure, there are at least two vinyl groups in the molecule, and in the case of crosslinking using a tatashi (CXI), an average number of more than two vinyl groups in the molecule. It is essential that it exists.

If the vinyl group content is less than 0.01 mol% on average, it will be difficult to achieve good vulcanization of the silicone rubber, and if the vinyl group content exceeds 2 mol%, good thermal stability will not be obtained. do not have.

The optional phenyl group is preferably selected from a range of 0 to 10 moles based on the total organic groups.

Its presence gives silicone rubber cold resistance and heat resistance, but if more than 10 mol% of phenyl groups are present, the remaining organic groups impair the processability of the composition and even reduce the cold resistance of silicone rubber. From the viewpoint of ease of synthesis of polyorganosilokinane, workability of the composition, and heat resistance of the resulting silicone rubber, a methyl group is preferred;
For example, a substituted hydrocarbon such as a cyanethyl group or a trifluoropropyl group may be used as a part of the silicone rubber in order to impart oil resistance and chemical resistance to the silicone rubber.

The amount of organic groups bonded to such silicon atoms is selected from the range of 1.980 to 2.002 per silicon atom, but if it exceeds 2.002, a satisfactory degree of polymerization cannot be obtained; This is because if it is less than .980, a good rubber-like elastic body cannot be obtained.

The degree of polymerization of polyorganosiloxane must be 1,000 or more in order to obtain a silicone rubber with good mechanical properties, but it is necessary to take into account the workability of the process of obtaining a homogeneous composition by cross-wire operation. Then, 2,000 to 10,0
A range of 00 is desirable.

The inorganic filler (B) used in the present invention is for imparting appropriate mechanical properties to the silicone rubber, and may be any one known to those skilled in the art, such as fumed silica, precipitated silica, silica air port. Examples include gel, calcined silica, crushed silica, diatomite, iron oxide, and titanium oxide.

These inorganic fillers may be used alone or in a mixture of two or more, or may be used as is, or their surface may be coated with polydimethylsiloxane, octamethylsiloxane, hexamethyldisilazane, etc. It may also be treated with an organosilicon compound.

The blending amount of the inorganic filler is 10 to 200 parts by weight per 100 parts by weight of the polyorganosiloxane (A), and 1
If it is less than 0 parts by weight, there is no effect, and if it exceeds 200 parts by weight, the silicone rubber becomes hard and difficult to process.

The organic peroxide (CXI) used in the present invention may be one normally used for vulcanization of this type of polydiorganosiloxane, such as benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, dicumyl peroxide, 2,5-bis(t-
butylberoxy)-2,5-dimethylhexane, 2,
5-bis-(t-butylperoxy)-2. 5-
Examples include dimethylhexyne and di-t-butyl peroxide, but 2,4-dichlorobenzoyl peroxide is preferred when hot air vulcanization is carried out at normal pressure.

The amount of these organic peroxides added is selected from the range of 0.1 to 10 parts by weight, preferably 0.3 to 2 parts by weight, based on 100 parts by weight of the polyorganosiloxane (A).

If the amount of organic peroxide added is too less than the above value, a sufficient vulcanization effect will not be obtained, and if it is added in excess, it will not only be meaningless, but will also reduce the thermal stability of the silicone rubber, which is damaged by decomposition products. and water vapor resistance.

The polyorganohydride diene siloxane (CX2) (a) used in the present invention may have any linear, branched, or cyclic siloxane chain, but in order to function effectively as a crosslinking agent, It is essential that one molecule has an average number of more than two Si-H bonds.

The organic group is generally a monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond, but monovalent groups selected from alkyl groups and phenyl groups are used due to the ease of obtaining raw materials and ease of handling. is desirable, and methyl group is particularly desirable.

The degree of polymerization is not particularly limited, but is preferably between 4 and 1,000.

If the degree of polymerization is less than 4, it is highly volatile and difficult to handle. If the degree of polymerization exceeds 1,000, the viscosity becomes high and it becomes difficult to mix with the vinyl group-containing polyorganosiloxane.

Among these, a polymerization degree in the range of 10 to 50 is more desirable from the viewpoint of ease of synthesis and ease of addition to vinyl group-containing polyorganosiwaxane as a liquid product.

The blending amount of polyorganohide diene siloxane is (
0 per 100 parts by weight of polyorganosiloxane A)
．． It is selected from the range of 1 to 10 parts by weight.

If it is less than 0.1 parts by weight, it will not be possible to supply the necessary number of Si-H bonds to crosslink and exhibit good physical properties, and if it exceeds 10 parts by weight, the Si-H bonds will be excessive and the silicone rubber will be This may impair heat resistance or reduce the density of Si--H bonds per molecule, resulting in a decrease in the mechanical properties of the silicone rubber.

Platinum or platinum-based compounds (CX2XO) used in the present invention include simple platinum, platinum adsorbed on a holding carrier, chloroplatinic acid, platinum-olefin complexes, complexes formed from platinum and alcohol, platinum and vinylsiloxane, and platinum coordination compounds such as zero-valent or divalent platinum-monophosphorus complexes.

The platinum content of the (CX2)(0) component is from IXIO-4 to 2X10-1% by weight, preferably from IXIO-3 to 1X1O-1% by weight, based on the prisoner component.

If it is too small, there is no effect, and if it is too large, the effect does not increase, it is uneconomical, and it also affects the heat resistance of the silicone rubber.

Component (D) used in the present invention is a fatty acid-modified polyorganosiloxane containing the above-mentioned R2 organic group, and is an essential component to achieve the purpose of the present invention, which is to prevent adhesion between silicone rubber and metal. .

The group represented by may be bonded to a silicon atom via an alkylene group having 2 or more carbon atoms.

In the latter case, synthesis via methylene group is difficult;
It is also easily hydrolyzed.

From the viewpoint of ease of synthesis, R4 has 4 to 30 carbon atoms, preferably 1
It is an aliphatic hydrocarbon group of 0 to 18.

When the number of carbon atoms is 3 or less, there is no effect of preventing adhesion, and when the number of carbon atoms is too large, the original fatty acid is difficult to handle.

Examples of organic groups bonded to silicon atoms other than this group include alkyl groups such as methyl and ethyl groups, allyl groups such as phenyl, and substituted hydrocarbon groups such as chloromethyl. A methyl group is preferable because it is easy to handle, easy to handle, and does not deteriorate the physical properties of silicone rubber.

In addition, the polyorganosiloxane is preferably in the form of a straight chain in view of the effect of preventing adhesion, and it is preferable that one R2 is bonded to each silicon atom at both ends of the molecular chain.

The blending amount of component (D) is 0.03 to 10 parts by weight, preferably 0.06 to 0, per 100 parts by weight of component (A).
It is 6 parts by weight.

If it is less than 0.03 parts by weight, there is no effect of preventing adhesion to metal, and if it exceeds 10 parts by weight, vulcanization becomes difficult.

If the amount exceeds 0.6 parts by weight, the heat resistance will decrease, so if heat resistance is desired, it is desirable not to exceed this amount.

Component (D) is liquid at room temperature, and since it is a polyorganosiloxane itself, it has the advantage of extremely good dispersibility in the base compound and ease of blending.

In the case of the present invention, organic acid metal salts, iron oxide, ferrite, etc. are added as heat resistance improvers to the polyorganosiloxane composition, platinum, fumed titanium oxide, etc. are added as flame retardants, and alkoxy terminals are added as processing aids. A low molecular weight organosiloxane having a group or a hydroxyl group, or a silane containing these groups may be added.

The present invention provides silicone that has good dispersibility in the composition of additives that have an adhesion prevention effect, has excellent adhesion prevention properties with metals, and does not impair the mechanical properties and heat resistance of the silicone rubber obtained by curing. A rubber composition was obtained.

The composition of the present invention is used as an insulating layer of a silicone rubber-coated electric wire that has good peelability between the core wire and the coating layer, and therefore has good workability during construction.The present invention will be explained below with reference to Examples. .

All parts in the examples indicate parts by weight.

Example 1 100 parts of a polymethylvinylsiloxane (degree of polymerization 6000) containing 0.1 mol% of methylvinylsiloxy units, the remainder being dimethylsiloxy units, and a specific surface area of 20 0m2/g
A base compound was obtained by mixing 30 parts of fumed silica using two rolls.

To this base compound 13053, 2,4-dichlorobenzoyl peroxide and ferric oxide were added in the amounts shown in Table 1 and mixed to obtain a silicone rubber composition.

This composition was applied to a tin-plated copper wire with a diameter of 3 mm and a thickness of 2 mm.
The wires were continuously coated using an extruder so that the wires were uniformly coated, and hot air vulcanization was performed at 450° C. for 1 minute to prepare electric wires.

This was heated at 150° C. for 8 hours, and the adhesion between the core wire and the silicone rubber layer was examined.

In addition, the core wire was removed from the electric wire and the physical properties of the silicone rubber were measured.

Furthermore, this was left in a dryer at 220° C. for 96 hours, and then its physical properties were measured.

These results are shown in Table 1.

Example 2 A similar test was conducted using the same composition as Composition 3 of Example 1 except that the following polyorganosiloxane was used in place of the polymethylvinylsiloxane of Example 1.

The results are shown in Table 2. Composition 7 Polymethylvinylsiloxane (polymerization degree 7000) whose terminal end is closed with a trimethylsilyl group and contains 0.2 mol of methylvinylsiloxy units, with the remainder consisting of dimethylsiloxy units Composition 8 A polymethylvinylsiloxane whose terminal end is closed with a trimethylsilyl group Polymethylvinylsiloxane (polymerization degree 6000) containing 0.5 mole of methylvinylsiloxy units and the remainder consisting of dimethylsiloxy units Composition 9 The terminal is closed with a trimethylsilyl group and contains 0 methylvinylsiloxy units. Polymethylvinylphenylsiloxane (polymerization degree 5000) containing 5 moles of diphenylsiloxy units and 5 moles of diphenylsiloxy units (polymerization degree 5000), 2,4-dichlorobenzoyl peroxide, titanium oxide zinc stearate were blended as shown in Table 3 to obtain a silicone rubber composition.

The results of conducting the same test as in Example 1 using this are shown below.

Example 4 In place of 2,4-dichlorobenzoyl peroxide in Example 1, 0.05% of a 25% isopropanol solution of chloroplatinic acid was used.
and polymethylhydrodiene siloxane (degree of polymerization 30) whose terminals are closed with trimethylsilyl groups is 0.5
As a result, there was no adhesion of the core wires.

Example 5 In place of the 2,4-dichlorobenzoyl peroxide of Example 1, 0.003 parts of [(C4H,0)3P)4Pt, and 6 to 7 moles of dimethylhydride dienesiloxy units and S
A test was conducted using the same composition as Composition 5 of Example 1, except that 0.6 part of polymethylhydrogensiloxane containing 33 moles of i02 units was mixed, and as a result, no core wire density was found.

Example 6 100 parts of the polymethylvinylsiloxane of Example 1, surface textured with trimethylchlorosilane, specific surface area 200 m2
/g of fumed silica 30 parts, dicumyl peroxide 1 part,
and 0.2 part of the following modified silicone were mixed to obtain silicone rubber compositions 13 to 15.

This composition was dispensed into two sheets of 150 mm x 150 x 1 mm using a roll, a tin-plated copper wire with a diameter of 1 mm was sandwiched between them, and pressure vulcanization was performed at 120° C. for 10 minutes.

The 2 mm thick sheet thus made was heated at 150°C for 10
Although it was heated for 0 hours, there was no adhesion between the core wire and the silicone rubber.

Regarding Composition 13, a similar experiment was conducted using a mild steel wire with a diameter of 1 mm, and as a result, there was no close contact between the core wire and the silicone rubber.

Claims (1)

[Scope of Claims] 1(A) The monovalent organic group bonded to the silicon atom is 1.0% per silica atom. 9 8 0 to 2.002 exist,
On average, 0.01 to 2 mol% of the total organic groups are vinyl groups, and the molecule contains at least 2 vinyl groups, however, when (CXI) is used, the molecule contains more than 2 vinyl groups on average. , 100 parts by weight of a polyorganosiloxane having a degree of polymerization of 1,000 or more. (B) 10 to 200 parts by weight of an inorganic filler, and (C
) (1) a catalytic amount of an organic peroxide, or (2) (a)
Polyorganohydride diene siloxane having an average number of more than 2 Si-H bonds in one molecule 0.1 to 10
parts by weight, and (0) a catalytic amount of platinum or a platinum-based compound, into which are the same or different alkylene groups, Q1 is an alkylene group, and R3 is a carbonized monovalent aliphatic having 4 to 30 carbon atoms. hydrogen group, n is O or 1,
m is an integer of 0 or 1 or more, n+m is 1 or more); A polyorganosiloxane having at least one siloxy unit in one molecule, represented by an organic group, a is 0, 1 or 2, b is 1 or 2, and a and b are 1, 2 or 3. A silicone rubber composition comprising 0.03 to 10 parts by weight based on component A). 2. The composition according to claim 1, wherein all silicon-bonded organic groups other than R2 in the polyorganosiloxane 2(D) are methyl groups. The composition according to claim 1, wherein 3(D) is a linear polyorganosiloxane. (However, R3 is R
Claim 1 is a linear polyorganosiloxane represented by 5 is a monovalent organic group and p is an integer.
Compositions as described in Section. 5. The composition according to claim 4, wherein R5 is a methyl group. 6. The composition according to claim 1, wherein R3 and R4 have 10 to 18 carbon atoms. 7 (D) blended amount is 0.06 per 100 parts by weight of (A)
The composition of claim 1, wherein the composition is 0.6 parts by weight.