JPH04236265A - Releasable silicone rubber composition and cured mold-product thereof - Google Patents

Abstract

PURPOSE:To provide a mold-releasable silicone rubber composition and its cured product suitable as material for a blocking matrix mold or a fixing roll. CONSTITUTION:The objective releasable silicone rubber composition and its cured product is composed of (A) 100 pts.wt. of an organopolysiloxane expressed by an average composition formula RaR<1>bSiO(4-a-b)/2 and having a viscosity of 100-100,000cp at 25 deg.C, (B) an organopolysiloxane expressed by an average compositional formula RcHdSiO(4-c-d)/2 and having a viscosity of 1-5,000cp at 25 deg.C, (C) 5-500 pts.wt. of an inorganic filler, (D) 1-100 pts.wt. of an organopolysiloxane expressed by an average compositional formula ReR<2>fSiO(4-(e+f))/2 and having a viscosity of 5-5,000cp at 25 deg.C and (E) a necessary catalytic amount (1-200ppm to (A)+(B)+(D)) of a platinum-group catalyst. The amount of the component B is selected to be sufficient to give 0.5-10 H atoms bonded to silicon atoms per one aliphatic unsaturated hydrocarbon group of the component A.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a releasable silicone rubber composition, and more particularly to a releasable silicone rubber composition suitable for automated molding and rationalization of line production.

0002

BACKGROUND OF THE INVENTION It has been known to add dimethylsiloxane oil to addition-curing silicone elastomers, which are characterized by their release properties, in order to adjust their hardness and improve their release properties. For example, as described in Shin-Etsu Chemical Co., Ltd.'s RTV rubber catalog for mold making and Japanese Patent Publication No. 61-4855, dimethyl with a viscosity of 10 to 5,000 cp at 25°C is used for fixing rolls of dry copying machines, etc. It is described that adding polysiloxane imparts lubricity and releasability to the roll surface and increases the number of copies until offset.

It is also known that improved mold release properties can be obtained by adding high molecular weight, non-functional diorganopolysiloxanes to silicone elastomer compositions.

0004

[Problems to be Solved by the Invention] However, when adding these dialkylorganopolysiloxanes, if the viscosity of the non-functional oil is lower than that of the vinyl group-containing dialkylpolysiloxane, which is the main oil that hardens into silicone rubber, , the addition effect cannot be fully exhibited, and in order to exhibit the effect, it is necessary to add a large amount of non-functional oil. Therefore, when a large amount of the non-functional oil is added, the physical properties of the cured silicone rubber are greatly reduced, and when used as a fixing roll, the diameter of the roll is reduced.

On the other hand, when the viscosity of the non-functional oil is high, although the effect of addition is good, the viscosity of the entire composition increases, making the molding operation difficult.

Furthermore, when the substituent of the added oil is an alkyl group with a large number of carbon atoms, although the mold releasability is improved, the heat resistance is poor, and it is difficult to use it in high temperature parts such as fixing rolls. there were.

[0007] Accordingly, an object of the present invention is to provide a releasable silicone rubber composition and a cured product thereof, which are suitable as a material for a molding matrix or a fixing roll.

[0008]

[Means for Solving the Problems] The above objects of the present invention are as follows:
(a) Average compositional formula Ra R1 b SiO (4-a-b
)/2, and the viscosity at 25°C is 100 to 10
0,000 cp organopolysiloxane: 100 parts by weight,

(b) Average composition formula Rc Hd SiO
(4-c-d)/2 and has a viscosity of 1 to 5,000 cp at 25°C: an organopolysiloxane in which the silicon-bonded hydrogen atom is the aliphatic unsaturated hydrocarbon group 1 in component (a) Enough amount to make 0.5 to 10 pieces per piece,

(c) Inorganic filler: 5 to 500 parts by weight, (d) Average composition formula Re R2 f SiO (4-(
It is expressed as e+f))/2, and the viscosity at 25°C is 5~
5,000 cp organopolysiloxane: 1-100
This was achieved by using a releasable silicone rubber composition comprising a platinum group catalyst in parts by weight and a catalytic amount, and a cured product thereof.

(A) Average compositional formula of component Ra R1 b
In SiO(4-ab)/2, R is an unsubstituted or substituted monovalent hydrocarbon group having no aliphatic unsaturated bond, R1 is an aliphatic unsaturated hydrocarbon group, and a is 1.
90-2.05, b is 0.0005-0.1 and a+b
is 1.91 to 2.06.

Specific examples of R include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, and octyl group;
Cycloalkyl groups such as cyclohexyl groups, phenyl groups,
Aryl groups such as tolyl groups, aralkyl groups such as benzyl groups and phenylethyl groups, or 3,3,3- groups in which some or all of the hydrogen atoms of these groups are substituted with halogen atoms, etc.
Examples include unsubstituted or substituted monovalent hydrocarbon groups having 1 to 10 carbon atoms, preferably 1 to 8 carbon atoms, such as trifluoropropyl group, and specific examples of R1 include lower alkenyl groups such as vinyl group and allyl group. Examples include groups.

The above organopolysiloxane is usually linear, but may be slightly branched. Although the aliphatic unsaturated hydrocarbon group may be present at either the end of the molecular chain or the side chain, it is preferred that the aliphatic unsaturated hydrocarbon group be present at least at both ends from the viewpoint of opportunistic properties after curing.

[0014] There may be only one type of R group in one molecule, or two or more types may be mixed. Moreover, the organopolysiloxane itself may be one type or a mixture of two or more types. In particular, by mixing a relatively low-viscosity organopolysiloxane and a relatively high-viscosity organopolysiloxane, it is possible to change the crosslinking density and the amount of inorganic filler. It has the advantage of being able to obtain hardness, and is suitable for determining the hardness of silicone rubber after curing.

From the viewpoint of workability, the viscosity of the component (a) organopolysiloxane at 25°C is 100 to 100,000, regardless of whether it is a single component or a mixture.
It is assumed that the range is 0 cp, but especially 200 to 50 cp.
,000 cp is preferred.

In the average compositional formula Rc HdSiO(4-c-d)/2 of component (b) used in the present invention, R is the same as R in component (a), for example, a methyl group,
Examples include ethyl group, propyl group, butyl group, octyl group, phenyl group, and 3,3,3-trifluoropropyl group. c is 1.0-2.1, d is 0.001-1.0
Moreover, c+d is 1.001 to 3.

[0017] This organohydrogenpolysiloxane can take any form of linear, branched, network, or cyclic, but is preferably linear or cyclic. There may be only one type of R group in one molecule, or two or more types may be mixed. Moreover, the organohydrogenpolysiloxane itself is not limited to one type, and may be a mixture of two or more types.

The hydrogen atom bonded to the silicon atom may be located at either the end of the molecular chain or the side chain, but in order to harden the component (a), the hydrogen atom bonded to the silicon atom is ) 0 per aliphatic unsaturated hydrogen group in the component
．． 5 to 10 pieces, preferably 1 to 4 pieces are required.

The viscosity of this component (b) at 25°C is:
From the viewpoint of workability or volatility, the range is from 1 to 5,000 cp, preferably from 10 to 5,000 cp.

[0020] The inorganic filler, component (c), used in the present invention is used to make the viscosity and fluidity of the composition appropriate, and to impart mechanical strength, hardness, thermal conductivity, etc. to the cured product. Specific examples include fumed silica, precipitated silica, fused silica, quartz powder, diatomaceous earth, aluminum silicate, titanium oxide, zinc oxide, iron oxide, alumina, calcium carbonate, zinc carbonate, carbon black, etc. Can be mentioned.

In the present invention, one or more appropriately selected inorganic fillers are used. This inorganic filler may also be surface-treated with organosilane, organosilazane, silicone oil, or the like.

If the amount of component (c) added is too small, the initial purpose will not be achieved, and if it is too large, not only will the fluidity of the composition deteriorate, but also the cured product will become brittle.
00 parts by weight to 5 to 500 parts by weight.

In the average compositional formula Re R2 f SiO(4-(e+f))/2 of component (2) used in the present invention, R is the same as R in component (a), and a specific example is methyl. Examples include ethyl group, propyl group, butyl group, octyl group, phenyl group, and 3,3,3-trifluoropropyl group.

[0024] e is 0.95 to 2.05, f is 0.0
01 to 1.0 and e+f is 1.95 to 2.06,
R2 is represented by a group selected from a hydroxyl group, an alkoxy group, an amino group, a glycidyl group, a mercapto group, or a monovalent organic group containing these groups.

The above R2 is an alkoxy group such as a hydroxyl group, a glycidyl group, a mercapto group, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a methoxyethoxy group, an ethoxyethoxy group; -NH2 group, an N-methylamino group, N-ethylamino group, N-propylamino group, N-butylamino group, N,N-dimethylamino group, N,N-diethylamino group, N-cyclohexylamino group, N-phenylamino group, N-benzylamino group Unsubstituted or substituted amino groups such as -(CH2)3-O
H, -(CH2)3-NH2,

[Chemical formula 1]

[Case 2]

[Chemical formula 3]

[C4]

-(CH2) 3 -SH, -(CH2
)3 -N(CH3)2, -(CH2)3 -NH-(CH2)2 -NH
2,-(CH2)3-O-(C2H4O)
Examples include groups such as 1 -H (1 represents a positive integer).

(d) Component 2 of organopolysiloxane
The viscosity at 5° C. is 10 to 5,000 cp, and the following specific examples can be given as such organopolysiloxanes.

[C5]

[C6]

[C7]

[Chemical formula 8]

[Chemical formula 9]

[Chemical formula 10]

[Chemical formula 11]

[Chemical formula 12]

[Chemical formula 13]

[Chemical formula 14]

[Chemical formula 15]

[Chemical formula 16]

[Chemical formula 17]

[Chemical formula 18] (Here, m and n each represent a positive integer)

002
8] The amount of the component (d) added is 1 to 100 parts by weight per 100 parts by weight of the organopolysiloxane of component (i);
Preferably it is 1 to 30 parts by weight. If the amount added is less than 1 part by weight, a sufficient effect on mold releasability will not be expressed, while if it is added in excess of 100 parts by weight, the effect on mold releasability will be saturated and it will be uneconomical. First, adding a large amount causes a decrease in physical properties.

[0029] Regarding component (2) containing an amino group, if the content of amino groups in the molecule is large, if a large amount of this is added, it will react with the platinum group compound that is the catalyst. Curing inhibition may occur. Therefore, (
When adding a large amount of the amino group-containing polysiloxane (d) component, it is preferable to keep the amino group content in one molecule low.

The platinum group catalyst used in the present invention as component (e) has an aliphatic unsaturated hydrocarbon group bonded to the silicon atom of component (c) and a hydrogen atom bonded to the silicon atom of component (b). It is a catalyst for addition reaction, specifically,
Particulate platinum, particulate platinum adsorbed on a carbon powder carrier, chloroplatinic acid, alcohol-modified chloroplatinic acid, chelate compounds of platinum, coordination compounds of chloroplatinic acid and vinylsiloxane, and palladium, rhodium, iridium, ruthenium. Examples include compounds of various metals such as osmium and osmium. Among these, platinum-based catalysts are particularly preferred.

[0031] The amount of platinum group catalyst added is determined by the components (a) and (b).
The amount of catalyst necessary to promote the hydrosilylation reaction with the components, preferably (a), (b) and (d).
1 to 200 pp of platinum group metal based on the total amount of components
m.

In the present invention, it is preferable to add an addition reaction retardant such as an organic nitrogen compound, an acetylene compound, or a tin compound in order to suppress the above-mentioned curing reaction and make handling easier. In addition, antistatic agents, heat resistant agents, flame retardants, pigments, glass fibers, carbon fibers, etc. may be added as necessary.

The composition thus obtained can be used as a silicone rubber for a molding matrix, or as a fixing roll material, etc., in applications where mold releasability of the cured rubber surface is required.

In particular, in the fixing section of recent dry copying machines, silicone rubber is used as the fixing backup roll material, Teflon is used as the heater roll, or silicone rubber is coated on the core metal, and furthermore, Many of these methods use PFA, fluorine latex, or fluorine silicone rubber as a surface coating agent to improve durability, but when the above materials are used, conventional dimethyl silicone oil is used. When internal addition is performed, dimethyl silicone oil that oozes out is not compatible with the surface coating agent, and repellency may occur.

On the other hand, the composition of the present invention has sufficient affinity for such surface layer agents, and therefore has the advantage that repellency is less likely to occur.

Furthermore, recently, copying materials have become full-color, and releasability for color toner has become required. The composition according to the invention,
For example, by forming a thin coating of several tens to hundreds of micrometers and then curing it, it provides superior mold release for color toner compared to conventional roll materials such as dimethyl silicone rubber or PFA tube coating. Effects can be obtained.

[0037]

Effects of the Invention The releasable silicone rubber composition of the present invention greatly improves the mold releasability of addition-curing silicone rubber after curing, and also improves mechanical properties when used as a molding matrix or fixing roll material. There is little deterioration in physical properties, and even during long-term use, mold shrinkage and roll diameter narrowing are small, making it extremely durable. In addition, since it is an addition-curing type, it not only has a fast curing reaction but also has excellent deep curing properties.
It also has the advantage of being able to significantly shorten the work process compared to peroxide-curing silicone rubber, making it suitable for automated molding using mechanical discharge mixing casting and streamlining line production.

[0038]

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto.

[0039]

[Examples 1 to 4 and Comparative Examples] In a kneader, 100 parts by weight of dimethylpolysiloxane having a viscosity of 5,000 cp at 25°C and whose ends were blocked with dimethylvinylsilyl groups and fumed silica (Aerosil 300: Nippon Aerosil Co., Ltd.) were placed in a kneader. Add 25 parts by weight of the company's product name), further add 5 parts by weight of hexamethyldisilazane and 2 parts by weight of water,
A base compound was obtained by heating at 150° C. for 2 hours. To 100 parts by weight of this base compound, 2.5 parts by weight of methylhydrogenpolysiloxane having the following structural formula and a viscosity of 15 cs at 25°C and a vinylsiloxane complex of chloroplatinic acid were added at 50 ppm in terms of platinum, A basic composition (I) was obtained. This composition
The properties after curing at 0°C/2 hours were as follows.

[Chemical formula 19]

Properties before curing: Viscosity (cp): 780 Properties after curing: Hardness (JIS-A): 35 Elongation (%)
:450 Tensile strength (kg/cm2):40

[0041] To 100 parts by weight of this basic composition (I), each of the following oils (A) to (E) as component (2) was added in the amounts shown in Table 1.

[Table 1] Example 1 Example 2 Example 3 Example 4 Comparative example Type of added oil A B
C D E addition amount (
parts by weight) 8 8
8 3 8 Number of sheets passed (sheets) 18,000 22,000
35,000 98,000 10
,000

[C20]

[C21]

[C22]

[C23]

Each of the obtained compositions was used as a surface coating for a heat fixing roll of a PPC (plain paper copier).
It was cured at 60°C for 2 hours on top of an elastomer molded body made of ordinary dimethyl silicone rubber.
It was molded to a thickness of μm and used as a roll for an actual color copy machine. Table 1 shows the results of evaluating the life of each roll based on the number of sheets of A4 size paper passed until the yellow toner was offset.

[C24]

Claims (2)

[Claims] Claim 1: (a) The average compositional formula is Ra R1 b
SiO(4-ab)/2 (wherein R is an unsubstituted or substituted monovalent hydrocarbon group having no aliphatic unsaturated bond,
R1 is an aliphatic unsaturated hydrocarbon group, a is 1.90-2.
05 and b is 0.0005 to 0.1, and a+b is 1
．． 91 to 2.06) and having a viscosity of 100 to 100,000 cp at 25°C: 100 parts by weight, (b) average compositional formula: Rc Hd SiO (4-c-d)
/2 (wherein, R is the same as R in component (A), c is 1.0 to 2.1, d is 0.001 to 1.0, and c
+d is 1.001 to 3) and has a viscosity of 1 to 5,000 cp at 25°C: an organopolysiloxane in which silicon-bonded hydrogen atoms are aliphatic unsaturated hydrocarbon groups in component (a) Sufficient amount to form 0.5 to 10 pieces per piece, (c) inorganic filler: 5 to 500 parts by weight,
(d) Average composition formula Re R2 f SiO(4-(e+
f))/2 (In the formula, R is the same as R in component (A), e is 0.95 to 2.05, and f is 0.001 to 1
．． 0 and e+f is 1.95 to 2.06, R2 is a group selected from a hydroxy group, an alkoxy group, an amino group, a glycidyl group, a mercapto group, or a monovalent organic group containing these groups. ) and a viscosity at 25° C. of 5 to 5,000 cp: 1 to 100 parts by weight, and a catalytic amount of a platinum group catalyst. 2. A cured product obtained by curing the composition according to claim 1.