JPS6225161A - Room temperature curing polyorganosiloxane composition - Google Patents

Abstract

PURPOSE:The titled composition capable of increasing extremely number of templatings and simplifying after-coating of duplicated cast material, being applied to silicone rubber matrix for templating to form a rubber-like film having improved releasability. CONSTITUTION:A composition consisting of (A) 100pts.wt. polyorganosiloxane having end groups hindered with a silanol group and 100-200,000cst viscosity at 25 deg.C, (B) 1-50pts.wt. copolymer of a polyoxyalkylene compound and polyorganosiloxane, (C) 1-50pts.wt. metallic salt of >=10C fatty acid containing no branched chains, such as zinc stearate or calcium stearate, (D) 0.1-30pts.wt. alkoxysilane shown by the formula (R<1> and R<2> are monofunctional hydrocarbon group; a is 0 or 1) and/or its partial hydrolysis condensate, (E) 0.01-10pt.wt. curing catalyst, preferably tin carboxylate and (F) 10-1,000pts.wt. organic solvent.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a room-temperature curable polyorganosiloxane composition, and more specifically, when applied to a silicone rubber mold for mold making, etc., it forms a rubber-like composition with excellent mold releasability. The present invention relates to an air temperature curable polyorganosiloquinone composition that forms a film.

[Technical background of the invention and its problems 1 Conventionally, room-temperature-curable polyorganosiloxane compositions, particularly polyorganosiloxane compositions that cure at room temperature and become rubber-like, have good heat resistance and chemical resistance. Because it has mold releasability, it is widely used as a molding material for cast products. However, silicone rubber molds for molding made from room-temperature-curable polyorganosiloxane compositions are not necessarily sufficient for applications that require even higher mold release properties; Moreover, it has the drawback that its mold release properties gradually decrease during use and its durability is poor.

For this purpose, for example, silicone oil whose molecular chain ends are blocked with trialkylsilyl groups is added to the room-temperature curable silicone rubber used as the molding material to make a matrix, or it is applied to the surface of the matrix each time the mold is made. Attempts have been made to improve mold releasability, but this silicone oil is not only applied every time a mold is made, but even when added to silicone rubber, the silicone oil is applied from the surface of the mold to the objects that come into contact with it. (casting product)
As a result, the mold releasability improved by the addition of silicone oil rapidly decreases, and in the case of cast products, the transfer of silicone oil causes the paint to deteriorate during post-painting. There is a drawback that repellent appears.

[Object of the Invention] The object of the present invention is to eliminate such drawbacks and to significantly increase the number of mold making cycles of silicone rubber molds, etc. by coating them on silicone rubber molds, etc. It restores the releasability of the silicone rubber matrix, etc., which has been lost due to multiple mold-making operations, and is a cast product that is reproduced from the coated silicone rubber matrix, etc. An object of the present invention is to provide a room temperature curable polyorganosiloxane composition which has features such as ease of coating.

[Structure of the Invention] As a result of intensive studies to achieve the above object, the present inventors found that when the composition of the present invention described later is applied onto the surface of a silicone rubber matrix, it quickly cures and releases at room temperature. Forms a rubber-like film with excellent moldability, greatly increases the number of times the casting (mold making) service life is used, recovers the mold releasability of the rubber mold that has deteriorated due to casting (mold making) work, and even improves the quality of cast products after casting. We have discovered a scale that exhibits an unexpectedly effective effect of eliminating paint repellency during painting, and have come up with the present invention.

In addition, the composition of the present invention forms a rubbery film on the surface of the silicone rubber matrix that maintains the mold release effect for a long time, so it can be poured like a commonly used silicone oil-based mold release agent or its equivalent mold release agent. There is no need to apply the coating 15 to the rubber matrix for each mold (molding), and the coating can be applied only when the H-shaped nature of the rubber matrix has decreased, thereby shortening the work process.

In short, the present invention comprises: (A) 100 parts by weight of a polyorganosiloxane whose terminal end is capped with a silanol group and whose viscosity at 25°C is 100 to 200,000 cst; (B) a polyoxyalkylene compound; 1 to 50 parts by weight of a copolymer with polyorganosiloxane, (C) 1 to 50 parts by weight of a metal salt of a fatty acid having 10 or more carbon atoms and no branching, (D) General formula % Formula %) (Formula %) where R'' and R2 are the same or different monovalent hydrocarbon groups, a represents 0 or 1) and/or a partially hydrolyzed condensate thereof 0.
1 to 30 parts by weight, (E) 0.01 to 10 parts by weight of a curing catalyst, and (F
) A room temperature curable polyorganosiloxane composition characterized by comprising 10 to 100 parts by weight of an organic solvent.

The component (Δ) used in the present invention is a silanol-terminated polyorganosiloxane that is normally used in condensed polysiloxane compositions that can be cured at room temperature, and provides excellent mechanical properties to the rubber-like elastic body after curing. The viscosity at 25°C is 100-.

It needs to be in the range of 200.000 03 t.

If the viscosity is less than 100 cSt, the elongation of the rubber-like elastic body after curing is insufficient, and if it exceeds 200,000 cSt, a uniform composition cannot be obtained. Examples of organic groups directly bonded to silicon atoms include methyl group and ethyl group. Base.

Alkyl groups such as propyl, butyl, and hexyl; alkenyl groups such as vinyl and allyl; aryl groups such as phenyl; aralkyl groups such as 2-phenylethyl; and 3,3.3- 1 such as 1-lifluoropropyl group, chloromethyl group, β-cyanoethyl group
Examples include substituted hydrocarbon groups, but methyl, vinyl, or phenyl groups are generally advantageous from the viewpoint of ease of synthesis.

Among them, the methyl group not only allows the raw material intermediate to be jqed the most easily, but also provides the lowest viscosity in relation to the content of siloquiline, which favors the balance of physical properties of the gel-like elastomer after curing. Therefore, it is preferable that 85% or more of goldstone full is a methyl group, and it is more preferable that substantially all of the right 1Bg is a methyl group. However, when heat resistance is required for the rubber-like elastic body after curing, it is recommended to use phenyl groups as part of the organic groups.

Component (B) used in the present invention is a component that imparts mold releasability to the rubber-like film after curing, and on the other hand, imparts post-paintability to cast products, and is a component that is a combination of a polyoxyalkylene compound and a polyorganosiloxane. It is a polymer. Examples of groups bonded to the silicon atom of polyorganosiloxane include alkyl groups such as methyl, ethyl, and propyl groups, and 1-nyl groups, excluding the bond with the polyoxyalkylene moiety. However, from the viewpoint of ease of synthesis, a methyl group is preferable. Examples of polyoxyalkylene compounds include polyoxyethylene, polyoxypropylene, and copolymers consisting of oxyethylene units and oxypropylene units. The molecular chain end of the polyoxyalkylene moiety may be a hydroxyl group, a methoxy group, a butoxy group, or the like. In view of long-term hydrolysis resistance, the bond between the polyoxyalkylene moiety and the polyorganosiloxane has at least b3 carbon atoms interposed between the silicon atom and the first oxygen atom of the polyoxyalkylene moiety. Examples of such bonds include trimethylene group, tetramethylene group, γ-(β-hydroxypropylene)′Axypropyl group, and the like.

In the molecular structure of such a polyoxyalkylene-polyorganosiloxane copolymer, the polysiloxane skeleton may be linear or branched, and even if the polyoxyalkylene is attached to the terminal of the polyorganosiloxane,
It may also be grafted as a side chain.

The blending amount of such component (B) is 1 to 50 parts by weight per 100 parts by weight of component A). If component (B) is less than 1 part by weight, it will not be possible to impart sufficient mold release properties to the rubbery film after curing and sufficient paintability to the cast product.
If it exceeds 50 parts by weight, a tough rubbery skin WA cannot be obtained.

Component (C) used in the present invention, when used in combination with component (B), provides sufficient mold release properties to the rubber-like film after curing.
It is necessary that the fatty acid moiety has at least 10 carbon atoms and has no branching. (C
) Components include zinc stearate, calcium stearate, potassium palmitate, and the like.

The blending amount of component (C) is 1 to 50 parts by weight per 100 parts by weight of component (A). If component (C) is less than 1 part Φ, sufficient releasability cannot be imparted to the cured rubbery skin I19, and if it exceeds 50 parts, a tough rubbery film cannot be obtained.

Component (D) used in the present invention is a component required for the composition of the present invention to cure to form a good rubber-like film, and has the general formula % formula % (where R1, R2 and a is an alkoxysilane represented by (as described above) and/or a partially hydrolyzed product thereof. Examples of R1 include alkyl groups such as methyl, ethyl, propyl, and butyl, phenyl, and vinyl groups, and R2 is preferably methyl and ethyl from the viewpoint of hydrolyzability of alkoxy groups. a is 0 or 1, and when a is 2.3 or 4, the Kurihashi effect is not affected and a cured film cannot be obtained. like this(
D) Components include methyltrimethoxysilane, ■ tiltrimethoxysilane, phenyltrimethoxysilane, vinyltrimethoxysilane, methyltriethoxysilane,
Examples include ethyltriethoxysilane, phenyltriethoxysilane, vinyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, and hydrolyzed or cohydrolyzed products of these alkoxysilanes.

The blending amount of component (D) is 0.1 to 30 parts by weight per 100 kg of component (Δ). (D) component is 0.1
If it is less than 3 parts by weight, a good rubber-like film will not be obtained after curing;
If the amount exceeds 0 parts by weight, the cured film will become brittle, which is not preferable.

The curing catalyst of component (E) used in the present invention is essential for condensing the composition of the present invention,
Examples of this include dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dioctoate, and tin octoate.

The amount used is the usual catalyst amount, 0.01 to 10 parts per 100 parts of component (A).

If it is less than 0.01 parts by weight, it will not cure, and if it is added in excess of 10 parts by weight, it will not be effective.

The organic solvent (F) component used in the present invention is used to appropriately adjust the viscosity and fluidity of the composition during coating work. Such an R-containing solvent may be any aliphatic or aromatic hydrocarbon-based inert solvent,
For example, n-hexane.

Mineral spirits, petroleum benzene, gasoline.

Examples include aliphatic hydrocarbon solvents such as kerosene, and aromatic hydrocarbon solvents such as toluene and xylene.

In the present invention, one or more types selected from the above-mentioned group are used. The amount of component ([) is 10 to 1000 per 100 parts by weight of component (A).
This is the middle section of the verse. If the compounding needle for component (F) is outside this range, the workability during application of the composition of the present invention will be poor and it will be impractical.

[Effects of the Invention] The room-temperature curable polyorganosiloxane composition of the present invention having the above-mentioned composition has excellent mold releasability in the rubber film formed when it is cured. Therefore, by applying the composition of the present invention to the surface of a silicone rubber matrix, etc., it is possible to obtain the effect of greatly increasing the number of times of casting (mold making). Furthermore, it imparts paint erodibility to the cast product. In addition, the mold-making process can also be shortened.

[Embodiments of the Invention] The present invention will be explained in more detail below by giving examples and application examples. In the Examples and Application Examples, all parts are by weight, 1yle is a methyl group, and 31J is a butyl group.

Example 1 100 parts of polydimethylsiloquiline having a viscosity of 3000 c3 t at 25°C and capped at both ends with silanol groups, 20 parts of a polyoxyalkylene-polysiloquiline copolymer having the following average molecular formula: Polyorganosiloxane composition 1 was prepared by mixing 10 parts of average molecular formula calcium stearate, 2 parts of phenyl+-rimethoxysilane, 0.5 parts of dibutyltin diacetate, and 500 parts of mineral svirit.

Example 2 has a viscosity of 20,000 c3t at 25°C,
100 parts of polydimethylsiloquiline with both ends capped with silanol groups, 10 parts of polyoxyalkylene-polysiloxane copolymer having the following average molecular formula, 5 parts of magnesium stearate, 3 parts of ethyl polysilicate, dibutyltin dilaline. Polyorganosiloxane composition 2 was prepared by mixing 1 part of urea-1, j3, and 100 parts of toluene.

Application example 1 Commercially available two-component integrated molding silicone rubber (product name T
SE350 (Toshiba Silicone Co., Ltd.) was molded and cured into a concave mold, and Composition 1 obtained in Example 1 was applied to the concave mold, and a casting (molding) test using polyester resin was conducted.

The results are shown in Table 1.

Table 1 Application example 2 Commercially available two-component condensation molding silicone rubber (product name T
S63562 (manufactured by Toshiba Silicone Co., Ltd.) was molded and cured into a concave mold, and Composition 2 obtained in Example 2 was applied to the concave mold to perform a casting test using a urethane resin.

The results are shown in Table 2.

Table 2 Application Example 3 Example 1 was applied to the silicone rubber concave molded in Application Example 2.
Compositions 1 and 2 obtained in Steps 1 and 2 were applied, and cast products of urethane resin were produced from these rubber molds, and then a coating test was conducted on the cast products.

The results are shown in Table 3.

Table 3 Good condition (no uneven coating)

Claims (1)

[Scope of Claims] 1 (A) 100 parts by weight of a polyorganosiloxane whose terminal end is capped with a silanol group and has a viscosity of 100 to 200,000 cSt at 25°C; (B) a combination of a polyoxyalkylene compound and a polyorganosiloxane; 1 to 50 parts by weight of copolymer, (C) 1 to 50 parts by weight of a metal salt of a fatty acid having 10 or more carbon atoms and no branching, (D) General formula R^1_aSi(OR^2)_4_-_a (Formula (wherein, R^1 and R^2 are the same or different monovalent hydrocarbon groups, a represents 0 or 1) and/or a partially hydrolyzed condensate thereof 0.1 to 30% by weight (E) 0.01 to 10 parts by weight of a curing catalyst, and (F) 10 to 1000 parts by weight of an organic solvent. 2. The composition according to claim 1, wherein the organic group bonded to the silicon atom in 2(A) is a methyl group. 3. The composition according to claim 1, wherein component (E) is a tin carboxylate.