JPS6352063B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a polyorganosiloxane composition whose cured state can be immediately determined by a change in color. [Technical background of the invention and its problems] Addition reaction type state silicone rubber compositions are produced by addition reaction of a polyorganosiloxane having an alkenyl group and a polyorganohydrodiene siloxane having a hydrogen atom bonded to a silicon atom with a platinum compound or the like. A composition that is cured using a catalyst for
It is already well known (see Japanese Patent Publication No. 43-27853, etc.). Conventionally, in order to examine the cured state of rubber obtained from these liquid silicone rubber compositions, it was necessary to actually touch the silicone rubber composition in the middle of curing and observe it with your finger, or measure the penetration and rubber hardness. I had to make a decision based on what I did. For example, when using liquid silicone rubber for mold making molds or liquid silicone rubber for dental impression materials, workers and dentists use silicone rubber each time they remove the silicone rubber mold from the master mold or the inside of the oral cavity. It was necessary to judge the hardening state of the rubber by touching it with one's fingers, and to continue observing it with one's fingers until it was ready to be demolded. For this reason, valuable time is wasted by the workers in determining the cured state, which often interferes with the original medical treatment activities. Furthermore, since it is not possible to judge when the curing is complete by touch, the mold is removed or the next work is carried out even though the rubber is not fully cured, which often results in problems such as damage to the rubber and adhesion to the original mold. Occasionally, this may occur. [Purpose of the Invention] The present invention is capable of detecting the hardening state of rubber by observing the state of hardening with a finger, or by measuring the penetration and hardening of rubber. The purpose of the present invention is to provide a polyorganosiloxane composition whose cured state can be easily determined. [Structure of the Invention] As a result of intensive research aimed at improving these disadvantageous aspects, the present inventor has developed a silicone rubber composition that is cured by the reaction between a hydrosilyl group and an alkenyl group bonded to a silicon atom. It has been found that by adding an azo dye as a third component, a polyorganosiloxane composition that changes color or disappears as the curing progresses and allows the curing state to be visually determined can be obtained. That is, the polyorganosiloxane composition of the present invention has (A) the following formula: (In the formula, R ¹ is an alkenyl group, R ² is a substituted or unsubstituted monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond, a is an integer of 1 or 2, and b is 0.
-2, a+b is an integer of 1-3) Polyorganosiloxane having at least two units represented by the following in the molecule: 100 parts by weight (B) The following formula: (In the formula, R ³ represents a substituted or unsubstituted monovalent hydrocarbon group, c is an integer of 0 to 2, d is an integer of 1 or 2, and c+d is an integer of 1 to 3) Polyorganohydrodienesiloxane having at least 3 hydrogen atoms bonded to silicon atoms in the molecule: Hydrogen bonded to silicon atoms for each R ¹ group in polyorganosiloxane (A) number of atoms is 0.5
(C) a catalyst selected from the group consisting of platinum and platinum compounds: 1 to 100 ppm as platinum atoms based on the polyorganosiloxane (A); and (D) an azo dye: polyorganosiloxane. It is characterized by comprising 1 to 2000 ppm of siloxane (A). The present invention will be explained in more detail below. Polyorganosiloxane (A) used in the present invention
has at least two alkenyl groups in one molecule directly bonded to a silicon atom. The polyorganosiloxane (A) may be either linear or branched, or a mixture thereof may be used. Examples of R ¹ in the above formula include a vinyl group, an allyl group, a 1-butenyl group, and a 1-hexenyl group, but a vinyl group is most advantageous in terms of ease of synthesis. Organic groups bonded to the silicon atom of R ² and other siloxy units include alkyl groups such as methyl, ethyl, propyl, butyl, hexyl, and dodecyl; aryl groups such as phenyl; β- Phenylethyl group, β
Examples include aralkyl groups such as -phenylpropyl, and also chloromethyl, 3,3,3-
Substituted hydrocarbon groups such as trifluoropropyl groups may also be mentioned by way of example. Among these, polyorganosiloxanes that are easy to synthesize and have the necessary degree of polymerization to maintain good physical properties after curing,
A methyl group is most preferred because it exhibits low viscosity before curing. In addition, when the composition of the present invention is used for casting, potting, coating, dipping, etc., it has properties suitable for this purpose, in particular, appropriate flowability before curing, and excellent physical properties after curing. In order to obtain the properties, the viscosity at 25℃ is 50~200000cP, especially 100~100000cP.
It is preferable that it is in the range of . If the viscosity is less than 50 cP, it will be difficult to obtain sufficient elongation and elasticity after curing, and if the viscosity exceeds 200,000 cP, workability in casting, potting, and other operations will be poor. The polyorganohydrodiene siloxane used as the component (B) used in the present invention must have at least three silicon-bonded hydrogen atoms in one molecule in order to form a network through crosslinking. It is. Examples of the organic group bonded to the silicon atom of R ³ and other siloxy units in the above formula include those similar to R ² in the component (A) above, but from the viewpoint of easy synthesis,
Most preferred is the methyl group. The polyorganohydrodiene siloxane (B) may be linear, branched or cyclic, or a mixture thereof may be used. In terms of imparting good physical properties to the composition itself after curing, component (B) includes the following a to c.
Compounds shown in are preferred. a Branched polyorganohydrodiene siloxane consisting of (CH ₃ ) ₂ HSiO1/2 and SiO ₂ units and having a content of hydrogen atoms bonded to silicon atoms in the range of 0.3 to 1.2% by weight of the molecular weight b The following formula: (where p is an integer of 3 to 100 and q is an integer of 0 to 100), and the content of hydrogen atoms bonded to silicon atoms is in the range of 0.5 to 1.6% by weight of the molecular weight. Organohydrogensiloxane c following formula: (where p is an integer of 1 to 100 and q is an integer of 0 to 100), and the content of hydrogen atoms bonded to silicon atoms is in the range of 0.5 to 1.6% by weight of the molecular weight. The amount of organohydrodienesiloxane (B) component used is 1 alkenyl group in component (A).
The amount is such that the number of hydrogen atoms bonded to silicon atoms in component (B) is 0.5 to 4.0, preferably 1.0 to 3.0. If the number of hydrogen atoms is less than 0.5, the curing of the composition will not proceed sufficiently, and the hardness of the composition after curing will be low.
If the amount is exceeded, the physical properties of the cured composition will deteriorate. The platinum-based catalyst as component (C) used in the present invention is (A)
This is used to promote the addition reaction between the alkenyl group of the component and the hydrosilyl group of the component (B), such as simple platinum, warmed platinic acid, platinum-olefin complex, platinum-alcohol complex, platinum coordination compound, etc. is exemplified. The amount of component (C) used is in the range of 1 to 100 ppm in platinum atoms relative to component (A). If the content is less than 1 ppm, the effect of the present invention cannot be achieved, and if it exceeds 100 ppm, no improvement in curing speed can be expected. The azo dye used as component (D) used in the present invention is most preferably one that is soluble in the polyorganosiloxane component (A) or (B). Since it can be used by dispersing and mixing it in a substance, it may be soluble in an organic solvent. Furthermore, the effects of the present invention are not lost even if the dye is simply mixed and dispersed in the polyorganosiloxane composition, so even if it is insoluble in components (A) and (B), it can be used. Examples of azo dyes include monoazo or polyazo dyes, metal complex azo dyes,
Examples include pyrazolone azo dyes, stilbene azo dyes, and thiazole azo dyes.
A disazo dye having two -) is most preferred. Examples of disazo dyes include Orient Oil Red 5B (manufactured by Orient Chemical Industry Co., Ltd., trade name);
Kayasetsu Retsudo 802 (manufactured by Nippon Kayaku Co., Ltd., trade name),
Examples include Oiled SA Extra (manufactured by Shirato Kagaku Kenkyujo Co., Ltd., trade name). The amount of component (D) used is in the range of 1 to 2000 ppm relative to component (A).
At the end of 1ppm, the effect of the present invention cannot be fully exhibited,
Moreover, if it is within 2000 ppm, it is sufficient to observe discoloration or decolorization, and if it is added more than that, the effect of the present invention may not be achieved. The composition of the present invention may additionally contain a filler as needed, and may also contain a solvent or other polyorganosiloxane to the extent that the effects of the present invention are not impaired. may be used together. Examples of such incidental additives are usually fumed silica, precipitated silica, quartz powder, diatomaceous earth, glass beads, toluene, hexane, polydimethylsiloxane, etc., but titanium oxide, iron oxide, etc. The combined use of additives that are originally colored or fillers with strong hiding power is not suitable for this purpose. Note that addition reaction type liquid silicone rubber cures even if it is left at room temperature, but it is also possible to further accelerate curing by heating. In the polyorganosiloxane composition according to the present invention,
Even in such heat curing, the rubber changes color or disappears as it hardens, and the cured state can be visually clarified. [Effect of the invention] In the case of ordinary addition-type liquid silicone rubber,
A rubber-like cured product is obtained by stirring and mixing a component consisting of a polyorganosiloxane having an alkenyl group and a platinum compound, and a component consisting of a polyorganohydrodiene siloxane having a hydrogen atom bonded to a silicon atom at a predetermined ratio. However, in the silicone rubber composition of the present invention,
By coloring at least one of the polysiloxane components by adding an azo dye, it becomes possible not only to determine the sufficient mixing state of the two components, but also to observe the cured state from the change in color. [Example] The present invention will be explained below with reference to Examples. In addition,
In the examples, all parts indicate parts by weight. Example 1 Component S-1(a) was prepared by adding and stirring an isopropyl alcohol solution of chloroplatinic acid at 30 ppm as platinum to 100 parts of polydimethylsiloxane having a viscosity of 350 cP at 25° C. and having both ends blocked with dimethylvinylsilyl groups. (CH ₃ ) ₂ Consists of HSiO1/2 units and SiO ₂ units,
5 parts of polymethylhydrodiene siloxane containing 1.02% by weight of hydrogen atoms bonded to silicon atoms and having a viscosity of 20 cP at 25°C, viscosity at 25°C
95 parts of 50cP polydimethylsiloxane with trimethylsilyl groups blocked at both ends and Kaya set red
Toluene solution of 802 (manufactured by Nippon Kayaku Co., Ltd., trade name) (based on base oil as Kaya Set Red 802)
100ppm was stirred and mixed and colored red. Component S-
1(b) was prepared. When 100 parts of S-1(b) was added to 100 parts of S-1(a) and stirred, the mixture uniformly turned red, and the adequacy of stirring could be clearly determined visually. Furthermore, when this material was left to cure at 25°C and 80°C, the red color changed to yellow as the rubber hardened, as shown in Table 1, and rubber hardening could be clearly determined from the color change. . Example 2 100 parts of a polydimethylsiloxane base oil with a viscosity of 5000 cP at 25°C and blocked with dimethylvinylsilyl groups at both ends, 10 parts of fumed silica Aerosil 200 (manufactured by Degutsusa Co., Ltd., trade name), (CH ₃ ) ₂ HSiO1/
2 parts of polymethylhydrodiene siloxane consisting of 2 units and ₂ units of SiO, containing 1.02% by weight of hydrogen atoms bonded to silicon atoms and having a viscosity of 20 cP at 25°C, 20 ppm of chloroplatinic acid (based on base oil as platinum) and A red composition S-2 was prepared by mixing and uniformly dispersing 50 ppm of OILED SA EXTRA (manufactured by Hakuto Gakuken Co., Ltd., trade name). When this product was left at 40°C, as shown in Table 2, it turned yellow as the rubber hardened, and rubber hardening could be clearly determined from the color change. Example 3 100 parts of a polydimethylsiloxane base oil with a viscosity of 20,000 cP at 25°C and blocked with dimethylvinylsilyl groups at both ends, 15 parts of Crystallite VX-SS (manufactured by Kasumori Co., Ltd., trade name), and trimethylsilyl groups at both ends. Blocked linear polymethylhydrodiene siloxane 1.5 with a silicon-bonded hydrogen content of 0.8% by weight and a viscosity of 20 cP at 25°C.
Red composition S-3 was prepared by mixing and uniformly dispersing 30 ppm of an isopropyl alcohol solution of chloroplatinic acid (based on base oil as platinum) and 70 ppm of Kaya Set Red 802. When this product was left at room temperature, the red color disappeared as the rubber hardened, and rubber hardening could be determined by the color change.

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Claims (1)

[Claims] 1 (A) The following formula: (In the formula, R ¹ is an alkenyl group, R ² is a substituted or unsubstituted monovalent hydrocarbon group that does not contain an aliphatic unsaturated bond, a is an integer of 1 or 2, and b is 0.
-2, a+b is an integer of 1-3) Polyorganosiloxane having at least two units represented by the following in the molecule: 100 parts by weight (B) The following formula: (In the formula, R ³ represents a substituted or unsubstituted monovalent hydrocarbon group, c is an integer of 0 to 2, d is an integer of 1 or 2, and c+d is an integer of 1 to 3) Polyorganohydrodienesiloxane having at least 3 hydrogen atoms bonded to silicon atoms in the molecule: Hydrogen bonded to silicon atoms for each R ¹ group in polyorganosiloxane (A) number of atoms is 0.5
(C) a catalyst selected from the group consisting of platinum and platinum compounds: 1 to 100 ppm as platinum atoms based on the polyorganosiloxane (A); and (D) an azo dye: polyorganosiloxane. A polyorganosiloxane composition comprising 1 to 2000 ppm of siloxane (A). 2. The composition according to claim 1, wherein R ¹ in (A) is a vinyl group. 3 The polyorganohydrodiene siloxane of (B) has the following formula: R ⁴ (CH ₃ ) ₂ SiO [(CH ₃ )HSiO[ _-P ]-(CH ₃ ) ₂ SiO]
_−q Si(CH ₃ ) ₂ R ⁴ [wherein R ⁴ represents a hydrogen atom or a methyl group,
p is 1 to 100 (provided that when both R ⁴ are methyl groups, p is 3 to 100), and q is an integer of 0 to 100. Composition. 4 The polyorganohydrodiene siloxane (B) consists of (CH ₃ ) ₂ HSiO1/2 units and SiO ₂ units,
The composition according to claim 1, wherein the content of hydrogen atoms bonded to silicon atoms is 0.3 to 1.2% by weight of the molecular weight. 5. The composition according to claim 1, wherein the azo dye (D) is a disazo dye.