JPH0723451B2 - Curable silicone composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a curable silicone composition, and more specifically, a two-part type room temperature vulcanization type which cures rapidly at a relatively low temperature to give a rubber-like cured product. It relates to a silicone composition.

[Prior Art] Room temperature vulcanizing silicone rubber (RTV rubber), which gives a rubber-like elastic body by undergoing a crosslinking / curing reaction at room temperature or a relatively low temperature, is a mold release or antifouling coating, sealant, water. None Widely used for manufacturing lithographic printing plates.

There are 1-pack type and 2-pack type RTV rubber, and there are 2 types of 2-pack type, addition type and condensation type, depending on the curing reaction mode. Each of these compositions has advantages and disadvantages,
It is used properly depending on the application and usage conditions.

A major problem in the two-pack type, especially in the condensation type composition is the balance between the curing speed and the pot life. From the viewpoint of workability, the faster the curing speed,
Further, the longer the pot life is, the more preferable, but these two have mutually contradictory characteristics, and it is extremely difficult to satisfy both.

The composition of the two-component / condensation-type RTV rubber is generally composed mainly of diorganopolysiloxane having silanol groups at both ends,
A crosslinking agent and a curing catalyst are added to it. Usually, a component other than the catalyst component is placed in a solution, and the catalyst is mixed at the time of use. Alkoxysilanes or organohydrogenpolysiloxanes are usually used as a cross-linking agent, which undergoes dealcoholization or dehydrogenative condensation reaction with silanol groups in the presence of a curing catalyst to crosslink and cure. As a curing catalyst, an organic tin compound such as dibutyltin diacetate, dibutyltin dilaurate or tin octenoate is generally used.

In such a composition, the means for increasing the curing rate is to increase the amount of catalyst, but in that case the pot life will naturally be shortened. That is, it becomes unusable due to changes such as thickening, gelation, deterioration of curability, or deterioration of physical properties of the cured product in a short time.

Reaction inhibitors are often added to extend pot life. Acetic acid is commonly used as a reaction inhibitor and its addition can extend the pot life considerably, but its curing is still insufficient and is not at a satisfactory level. Acetic acid also has problems of odor and corrosiveness, and there is a problem in adding a large amount.

As described above, it is extremely difficult to achieve both curability and pot life in a two-component RTV rubber, and there is currently no two-component RTV composition having a satisfactory curing speed and pot life.

[Problems to be Solved by the Invention] The present invention solves the problems in the two-pack type RTV rubber as described above, has a very fast curing speed, a long pot life, and has no odor or odor. It is an object of the present invention to provide a curable silicone composition having no problem of corrosion.

[Means for Solving Problems] The present invention relates to a curable silicone composition containing the following components as essential components.

(A) A linear diorganosiloxane represented by the following general formula (I) having silanol groups at both ends. (R ¹ and R ² are alkyl groups, alkenyl groups or aryl groups having 1 to 10 carbon atoms, and R ¹ and R ² may be the same or different. N is a number of 100 to 10,000.) (B) a cross-linking agent represented by the following (a) and / or (b) (a) a compound represented by the following general formula (II) or a condensate thereof (R ³ O) _m SiR ⁴ _4-m ( II) (R ³ is an alkyl group or an alkenyl group having 1 to 5 carbon atoms, and R ⁴ is a monovalent group having 1 to 10 carbon atoms. M is 2 to 4
Is the number of. ) (B) An oligomer or polymer having a repeating unit represented by the following general formula (III) (R ⁵ is an alkyl group, an alkenyl group or an aryl group having 1 to 10 carbon atoms. P is a number of 1 to 100.) (c) A metal having a valence of 2 or more and acetylacetone or acetoacetic acid ester. Complex compound of (d) Acetylacetone and / or acetoacetic acid ester The present invention will be described in more detail below.

The component (a) in the present invention is a linear diorganopolysiloxane represented by the following general formula (I) and having silanol groups at both ends.

R ¹ and R ² are alkyl groups, alkenyl groups or aryl groups having 1 to 10 carbon atoms, and R ¹ and R ² may be the same or different. n is a number from 100 to 10,000. Generally, R ¹ and R ² are preferably 60% or more of a methyl group and 40% or less of a vinyl group or a phenyl group because of good physical properties.

The crosslinking agent as the component (b) in the present invention is a crosslinking agent represented by the following (a) and / or (b). 2 functional groups
Although it has more than one, it is preferable to have more than three.

(A) A compound represented by the following general formula (II) or a condensate thereof (R ³ O) _m SiR ⁴ _4-m (II) (R ³ is an alkyl group or an alkenyl group having 1 to 5 carbon atoms. , R ⁴ is monovalent having 1 to 10 carbon atoms, and may have a double bond, an ester bond, an ether bond, or the like in the chain, and may have a substituent such as a halogen or an epoxy group. M is a number of 2 to 4, preferably 3 or 4. That is, alkoxysilanes, and specific examples of the cross-linking agent include methyltrimethoxysilane, ethyltrimethoxysilane, and vinyltrimethoxy. Silane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, tetramethoxysilane, tetrae Kishishiran, tetrabutoxysilane and the like. One of these substances may be used, or two or more different substances may be mixed and used.

(B) An oligomer or polymer having a repeating unit represented by the following general formula (III) (R ⁵ is an alkyl group, an alkenyl group or an aryl group having 1 to 10 carbon atoms. P is a number of 1 to 100.) That is, it is generally called an organohydrogenpolysiloxane. , Those comprising only the repeating unit represented by the above general formula (III), or those comprising both the repeating unit represented by the above general formula (III) and the like.

(R ⁶ and R ⁷ are an alkyl group, an alkenyl group or an aryl group having 1 to 10 carbon atoms. Q is a number of 1 to 100.) Examples of commercially available compounds having such a structure include SH. −
1107 (manufactured by Toray Silicone Co., Ltd.) and KF-99 (manufactured by Shin-Etsu Chemical Co., Ltd.).

The metal complex compound as the component (c) in the present invention is a catalyst that accelerates the condensation / crosslinking reaction of both the components (a) and (b). The metals used here are Fe, Mn, Co, Al, Zr.
Examples of the metal having a valence of 2 or more include Fe, Mn, and Zr. These metals are used as a complex compound with acetylacetone or an acetoacetic acid ester (preferably an alkyl ester having 5 or less carbon atoms), and among them, a complex compound of iron (III) and acetylacetone is particularly preferable.

The component (d) in the present invention is a component that acts as a stabilizer, and one or more compounds selected from acetylacetone or acetoacetate, or acetylacetone and acetoacetate are used in combination. As the acetoacetic acid ester, the alkyl group has 1 to 5 carbon atoms.
Alkyl esters of are preferred.

A preferable composition ratio of the above components is 3 to 100 parts by weight, preferably 5 to 50 parts by weight of the component (b) with respect to 100 parts by weight of the component (a).
Parts by weight, component (c) 0.1 to 10 parts by weight, more preferably 0.5
˜5 parts by weight, component (d) 0.5 to 100 parts by weight, more preferably 1 to 50 parts by weight.

In addition to the above essential components, various additives may be added to the composition, if necessary. Examples of such additives include dyes / pigments, antistatic agents, fillers, plasticizers and the like. The addition of a suitable amount of diorganopolysiloxane oil, which has no functional groups or only one silanol group, as a plasticizer often gives good results in improving the adhesion of the coating film.

The above components of the present silicone composition are preferably dissolved in a suitable solvent and used as a solution for coating. Although it is not impossible to prepare a composition without using a solvent, it is generally difficult to form a homogeneous system because the component (c) has a low compatibility with the silicone component.

The solvent used does not have a functional group (OH group, amino group, etc.) that easily reacts with the silicone composition components, and has solubility for each of the components (a) to (d). If there is no particular limitation, for example, various hydrocarbons, carboxylic acid esters, ketones, ethers and the like can be used. Among them, preferable are n-paraffin hydrocarbon or isoparaffin hydrocarbon, ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran and the like. These can be used not only alone but also as a mixture of two or more kinds. Generally, hydrocarbons are preferable from the viewpoint of coatability, but the solubility of the component (c) is not sufficient, while ketones, esters and the like have excellent solubility of the component (c), but the coatability is Since they tend to be inferior, it is preferable to mix and use these solvents in an appropriate ratio to give preferable results.

The ratio of the solvent used is such that the nonvolatile content in the solution ((a)
It is preferable that the concentration of (b) and (c) is about 5 to 50% by weight. In order to store the solution for a long period of time, it may be divided into two kinds of solutions, and both solutions may be mixed immediately before use. For that purpose, the component (a) is used.
The solutions may be separated as in (b) and (c) and (d) or (a), (c), (d) and (b), and may be used as separate solutions.

The above solution is generally used for the purpose of applying and curing it on a substrate to obtain a cured silicone rubber coating film. Any ordinary coating technique can be applied to the substrate. The silicone composition coating film applied on the substrate is heat-treated at the same time as the solvent is removed or after the solvent is removed,
A cross-linking reaction occurs to cure rapidly. The solvent is removed by natural drying or forced drying at room temperature or high temperature after applying the silicone composition solution. Usually, drying and curing are simultaneously performed in a heat treatment atmosphere immediately. The temperature of the heat treatment is in the range of 50 ° C to 300 ° C, more preferably 80 ° C to 250 ° C. Although the time required for the heat treatment varies depending on the composition of silicone, the coating amount, the treatment temperature, the type of the substrate, etc., it may be generally a short time, and is usually in the range of 5 seconds to 5 minutes.

The components that play an important role in the composition of the present invention are the catalyst component of (c) and the stabilizer component of (d), and it is possible to achieve both good curability and long pot life by the combination of both. You can do it. The component (c) is extremely effective as a curing catalyst, and can be used in a very short time (a).
(B) Both components can be crosslinked and cured, but the pot life is remarkably short, and this alone has little practicality. That is, although the curability is excellent immediately after mixing, the curability rapidly decreases with time, and the curability is almost lost after 2 to 3 hours at normal temperature. However,
When the component (d) is made to coexist, the pot life can be surprisingly extended and the pot life can be obtained for several days to several tens of days at room temperature with almost no loss of curability. . Furthermore, the stabilizer (d) does not have an irritating odor or corrosiveness, unlike acetic acid which is usually used as a stabilizer, and is also very preferable in this respect.

[Effects of the Invention] As described above, the curable silicone composition of the present invention has an extremely good curability and a long pot life, and has no odor or corrosiveness, and thus has a conventional composition. The workability is significantly improved. In general, the curability and pot life are difficult to be compatible with each other, and thus the properties of the present composition are surprising.

[Examples] Examples of the present invention will be described below, but the present invention is not limited to these examples.

All "parts" used in the examples indicate parts by weight.

(1) Preparation of Silicone Solution Solutions having the following two compositions were prepared.

(2) Preparation of Catalyst Solution Solutions having the following three compositions were prepared.

(3) Examples, Comparative Examples Example 1, Comparative Examples 1-1, 1-2 For each 8 parts of the silicone solution A, the catalyst solution (-) 1
Parts at a ratio of 1 part, and these liquids are applied onto a polyethylene terephthalate film (“Lumirror” manufactured by Toray Industries, Inc.) having a thickness of 100 μm using a wire bar coater (the amount after drying is 2 g. / m ² ), immediately put in a hot air dryer at 150 ° C., heat-treated for a predetermined time, and then examined the cured state of the coating film by touching with a finger. Furthermore, after the liquid was stored at room temperature for a predetermined time, the same experiment was conducted to examine the change in curability.

The results are shown in Table 1.

Example 2, Comparative Examples 2-1, 2-2 8 parts of the silicone solution B was mixed at a ratio of 1 part of the catalyst solution (-), and the change in curability was examined in the same manner as in Example 1.

The results are shown in Table 2.

As described above, the silicone composition of the present invention (Examples 1 and 2)
Shows that both the curability and the pot life are significantly superior to those of the conventional composition (Comparative Examples 1-2 and 2-2). Also, it is found that even when the catalyst of the present invention is used, the pot life is remarkably inferior when the stabilizer component of the component (d) is not added (Comparative Examples 1-1 and 2-1).

Examples 3 to 10 The following catalyst solution (-) was mixed with 8 parts of the silicone solution A at a ratio of 1 part, and the change in curability was examined in the same manner as in Example 1.

The results are shown in Table 3.

As described above, the silicone composition of the present invention (Examples 3 to 1)
In 0), even if the addition amount of iron (III) acetylacetonate was changed in a wide range from 0.0009 to 17.9 parts by weight, it was compared with Comparative Examples 1-1, 1-2, 2-1, 2-2. Curability,
You can see that the pot life is excellent.

However, when the addition amount is small, the pot life is very excellent, but the curability is slightly inferior. Further, when the addition amount is large, the curability is very excellent, but the pot life is slightly inferior. That is, as described above, the effect of the present invention is further enhanced by setting the addition amount of iron (III) acetylacetonate, which is the component (c), to 0.1 to 10 parts by weight, further 0.5 to 5 parts by weight. You can see that

Claims (3)

[Claims] 1. A curable silicone composition containing the following components (a) to (d) as essential components. (A) A linear diorganosiloxane represented by the following general formula (I) having silanol groups at both ends. (R ¹ and R ² are alkyl groups, alkenyl groups or aryl groups having 1 to 10 carbon atoms, and R ¹ and R ² may be the same or different. N is a number of 100 to 10,000.) (B) a cross-linking agent represented by the following (a) and / or (b) (a) a compound represented by the following general formula (II) or a condensate thereof (R ³ O) _m SiR ⁴ _4-m ( II) (R ³ is an alkyl group or an alkenyl group having 1 to 5 carbon atoms, and R ⁴ is a monovalent group having 1 to 10 carbon atoms. M is 2 to 4
Is the number of. ) (B) An oligomer or polymer having a repeating unit represented by the following general formula (III) (R ⁵ is an alkyl group, an alkenyl group or an aryl group having 1 to 10 carbon atoms. P is a number of 1 to 100.) (c) A metal having a valence of 2 or more and acetylacetone or acetoacetic acid ester. Complex compound of (d) Acetylacetone and / or acetoacetic acid ester 2. The curable silicone composition according to claim 1, wherein the components (a) to (d) have the following composition ranges. (A) 100 parts by weight (b) 3 to 100 parts by weight (c) 0.1 to 10 parts by weight (d) 0.5 to 100 parts by weight 3. The curable silicone composition according to claim 1, wherein the components (a) to (d) have the following composition ranges. (A) 100 parts by weight (b) 5 to 50 parts by weight (c) 0.5 to 5 parts by weight (d) 1 to 50 parts by weight