JPH05140471A - Colorant and colored silicone rubber composition - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a colorant for silicone rubber, which has excellent fastness and does not undergo discoloration or discoloration even if a large heat history is applied, and does not discolor or discolor even after long-term exposure. .. [Structure] At least one of diketopyrrolopyrrole, isoindolinone, and brominated phthalocyanine as a pigment.
A coloring agent characterized by using three or more and siloxane as a vehicle.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a coloring agent for coloring silicone rubber, and more specifically, it does not discolor even under a large heat history and does not discolor even after long-term exposure. The present invention relates to a coloring agent for silicone rubber having excellent fastness, and a colored silicone rubber composition containing the coloring agent.

[0002]

TECHNICAL BACKGROUND AND PROBLEMS OF THE INVENTION It is widely practiced to compound a compound generally called silicone, particularly silicone rubber, with a pigment to give arbitrary coloring. Silicone rubber is also used in applications where it has a large heat history and is exposed to high temperatures because of its good heat resistance. It goes without saying that the silicone rubber used for these purposes is also required to be colored arbitrarily. On the other hand, pigments have a large surface free energy, specific surface area, polarity, etc.
It has a strong physical activity and is not necessarily compatible with the vehicle. Particularly in the case of silicones having a low polarity and having no crystallized portion, pigments which can be well dispersed are limited to azo pigments, azo lake pigments, reduced phthalocyanine pigments, nitriso pigments and the like. However, these have poor heat resistance,
It was easily discolored and discolored at about 200 ° C and was not suitable for practical use. Further, if a heat-resistant pigment such as a perylene-based pigment, a quinacridone-based pigment, a perylene-based pigment, or a slene-based pigment is used, naturally a highly heat-resistant silicone colorant can be obtained. The dispersibility was poor and it was necessary to add a surfactant. However, these surfactants adversely affect the physical properties of silicone at high temperatures, and no practical technique has been established.

[0003]

OBJECTS OF THE INVENTION The present invention has been devised in view of the above-mentioned prior art, and an object thereof is to provide a coloring agent for silicone having excellent heat fastness and dispersibility.

[0004]

DETAILED DESCRIPTION OF THE INVENTION The present inventors have conducted extensive studies to achieve the above object, and as a result, found that an extremely excellent coloring agent for silicone can be obtained by using a specific compound as a pigment and using siloxane as a vehicle. The present invention has been completed. That is, the present invention uses at least one or more of diketopyrrolopyrrole, isoindolinone, and brominated phthalocyanine as a pigment, and uses a siloxane as a vehicle, and a colored silicone containing the colorant. It relates to a rubber composition.

The main component of the colorant of the present invention may be any polysiloxane whose main chain is a bond of silicon-oxygen, and may be any polysiloxane that is generally widely used. The organic group bonded to the silicon atom is a monovalent substituted or unsubstituted hydrocarbon group, such as a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an alkyl group such as a dodecyl group, and a phenyl group. Aryl group, vinyl group,
An unsubstituted hydrocarbon group such as an alkenyl group such as a propenyl group, a butenyl group, a hexenyl group, an aralkyl group such as a β-phenylethyl group, and a β-phenylpropyl group,
Substituted hydrocarbon groups such as chloromethyl group and 3,3,3-trifluoropropyl group are exemplified. In general, a methyl group, a vinyl group, a phenyl group and a 3,3,3-trifluoropropyl group are often used because of their easiness of synthesis and workability.

In the present invention, at least one of diketopyrrolopyrrole, isoindolinone and brominated phthalocyanine is used as the pigment. These pigments are red / orange, yellow are
Is a green / blue system, and any of these can be used alone or as a mixture, and the dispersion performance is extremely excellent when siloxane is used as a vehicle. or,
All of these are commercially available and easily commercially available from pigment manufacturing companies. The reason why these three kinds of pigments are excellent in dispersibility with siloxane has not been clarified yet, but a structure in which an intermolecular force that facilitates electrochemical compatibility with the siloxane interface is likely to work. It is presumed that it is because they have it. The amount of the pigment to be mixed is not particularly limited, but as an effective colorant, a pigment having a high pigment concentration is preferred.
A range of 500 parts by weight is preferred.

A filler, a heat resistance improver, an adhesion aid and the like may be optionally added to the colorant, and other polyorganosiloxane may be added within a range not impairing the effects of the present invention. You may use together. As such, usually
Examples thereof include fumed silica, precipitated silica, reinforcing filler such as diatomaceous earth, aluminum oxide, zinc oxide, zinc carbonate, glass beads, and polydimethylsiloxane.

The blending amount of the colorant of the present invention with respect to the silicone rubber to be colored is not particularly limited, and it may be blended in such an amount that the desired color development is obtained. The obtained colored silicone composition exhibits excellent heat resistance and fastness as described above, and also has excellent dispersibility of the coloring agent, and thus is suitably used in various fields such as heat resistance applications. The silicone rubber used here is not particularly limited, and any known millable silicone rubber or liquid silicone rubber can be used.

[0009]

According to the present invention, a colorant for silicone rubber having excellent fastness which does not discolor even if a large heat history is applied and does not discolor even when exposed for a long period of time. Can be provided.

[0010]

EXAMPLES The present invention will be described in more detail with reference to the following examples. In the examples, “part” means “part by weight”.

Example 1, Comparative Examples 1-2 A polyorganosiloxane having a vinyl group content of 0.12 mol% and an average degree of polymerization of 5500 was charged into a kneader, and various pigments shown in Table 1 were blended in the amounts shown in Table 1 to obtain a uniform mixture. The compound (colorant) was obtained. Next, 0.5 parts of each of these is added to the millable silicone rubber "TSE221-4U" manufactured by Toshiba Silicone Co., Ltd.
Add to 100 parts of the specified vulcanizing agent (2,5-dimethyl-2,5
0.5 parts of (ditertiary butyl peroxyhexane) was added and pressed at 170 ° C. for 10 minutes. At this point, the dispersed state was visually observed. After radiating heat, place in an oven at 250 ° C
I put it in for a week and saw the discoloration. For confirmation of heat discoloration, see JIS
Z8723 The surface color was compared according to the comparison method. However, since the records of evaluation are halfway, it is determined based on JIS L0844 dyeing fastness test method against washing.
JIS L0804 (gray scale for discoloration) and JIS L0805
(Gray scale for contamination) was used to determine the grade. The results are also shown in Table 1.

[0012]

[Table 1]

Example 2 and Comparative Example 3 Polymethylsiloxane having a viscosity of 5000 cP was mixed with the various pigments shown in Table 2 in the amounts shown in Table 2 to obtain a uniform compound (colorant) with a stirrer. Next, 2.5 parts of each of these are used as a one-component addition type liquid silicone rubber "TS TS" manufactured by Toshiba Silicone Co., Ltd.
E3221 ”was added to 100 parts and mixed uniformly. This was made into a sheet having a thickness of 2 mm with a spatula, vulcanized at 150 ° C for 30 minutes, and then radiated. Here, the dispersed state was visually confirmed. It was placed in an oven at 300 ° C. for 24 hours, and its discoloration was observed and evaluated in the same manner as above. The results are also shown in Table 2.

[0014]

[Table 2]

Claims (2)

[Claims] 1. A colorant comprising at least one of diketopyrrolopyrrole, isoindolinone and brominated phthalocyanine as a pigment, and a siloxane as a vehicle. 2. A colored silicone rubber composition containing the coloring agent according to claim 1.