WO2009048162A1 - Silicone rubber composition for templating matrix and templating matrix - Google Patents

Abstract

It is intended to provide a silicone rubber composition for a templating matrix which has an excellent mold release property, gives less stain to replicated products, and is excellent in defoaming of a material before curing. More particularly, it is a silicone rubber composition for a templating matrix containing (A) a polyorganosiloxane having 2 or more alkenyl groups binding to a silicon atom in one molecule and a viscosity at 25ºC of 500,000 to 1,000,000 centipoise (100 parts by weight); (B) a polyorganohydrogensiloxane having 3 or more hydrogen atoms binding to a silicon atom in one molecule (an amount such that the number of hydrogen atoms binding to a silicon atom per alkenyl group binding to a silicon atom in the component (A) is 0.4 to 4); (C) a platinum compound (1 to 200 ppm by weight in terms of platinum atom relative to the component (A)); and (D) a polydimethylsiloxane having an alkoxy group with 1 to 3 carbon atoms binding to a silicon atom at its molecular terminal and an average degree of polymerization of 5 to 500 (0.1 to 10 parts by weight).

Description

Silicone rubber composition for mold master and mold master

 The present invention relates to a silicone rubber composition excellent in releasability used as an inversion matrix for mold making and a mold taking mold obtained therefrom. Background art

 Silicone rubber molds used as molds for mold reversal require mold release durability. In an attempt to improve the mold release durability of the silicone rubber mold, a hydrophobized reinforcing siliceous filler using a silazane compound or a compound having an additional functional group is used in combination. Techniques such as combining those treated with strong hydrophilic silica have been proposed. According to these methods, although improvement in mold release durability of silicone rubber molds is recognized, mold release for resins such as epoxy resins having high physical properties and urethane resins, which are the mainstream of current cast resin materials. Sex is not enough.

 On the other hand, JP-A 7-1 1 8 5 3 4 proposes to add a non-crosslinkable silicone polymer having a chain length longer than the base polymer to be bridged for the purpose of further improving the releasability. In JP-A 2 0 0 0— 2 8 9 0 3 4, the organopolysiloxane base polymer forming the silicone rubber mold has a refractive index difference with this base polymer of not less than 0.01, It has been proposed to add a non-crosslinkable oily substance with a melting point of less than 100 ° C, which has greatly improved mold release properties.

However, the blending of these types of non-crosslinkable silicone polymers has problems such as the exudation of oil, which fouls replicas and makes it difficult for the material before curing to defoam. Disclosure of the invention

 The present invention has been made in view of the above circumstances, and is a silicone rubber composition for a mold master that is excellent in releasability, has little fouling of a duplicate, and has excellent defoaming properties of a material before curing. The purpose is to provide.

 As a result of repeated studies to achieve the above-mentioned object, the present inventors have a liquid silicone rubber composition having an alkoxy group having 1 to 3 carbon atoms bonded to a silicon atom at the molecular end, and an average polymerization. Silicone rubber composition for mold-making mold with excellent releasability, less fouling of replicated products, and excellent defoaming property of the material before curing. The inventors have found that a product can be obtained and have completed the present invention.

 That is, the present invention

 (A) a polyorganosiloxane having two or more alkenyl groups bonded to a silicon atom in one molecule and having a viscosity at 25 ° C of 50 to 100 million centipoise; 100 parts by weight

(B) Polyorganohydrogensiloxane having 3 or more hydrogen atoms bonded to a key atom in one molecule; (A) Bonded to a key atom for one alkenyl group bonded to a key atom in component (A) Amount of 0.4 to 4 hydrogen atoms

(C) platinum-based compound; (A) component is 1 to 200 ppm by weight in terms of platinum atom

 (D) a polydimethylsiloxane having an alkoxy group having 1 to 3 carbon atoms bonded to a silicon atom at the molecular end and an average degree of polymerization of 5 to 500; 0.1 to 10 parts by weight

Is a silicone rubber composition for a molding mother mold characterized by comprising Detailed Description of the Invention

The present invention is described in detail below. The alkenyl group-containing polyorganosiloxane (Α) used in the present invention has two or more alkenyl groups bonded to a silicon atom in one molecule, and the siloxane skeleton is either linear or branched. It may also be a mixture thereof. Examples of the alkenyl group include vinyl, allyl, 1-butenyl, and 1-hexenyl. A vinyl group is preferable because of ease of synthesis. Substituents bonded to a key atom other than an alkenyl group Examples thereof include: an aralkyl group such as methyl, ethyl, propyl, butyl, hexyl and dodecyl; an aryl group such as phenyl; an aralkyl group such as 2-phenylethynyl and 2-phenylpropyl; chloromethyl; 3, 3, 3-trifluoro Examples thereof include substituted carbon hydrogen groups such as isopropyl. Of these, the methyl group is most preferred because it is easily synthesized.

 Furthermore, component (A) is a base polymer for addition reaction type curable polyorganosiloxane, and 0.01% by mole or more of all organic groups bonded to the silicon atom are alkenyl groups. is required. Its viscosity at 25 ° C is not particularly limited, but it is more preferably 50 centipoise or more, especially for the purpose of rubber elastic bodies with mechanical properties, and it is necessary to have fluidity before curing. Is preferably less than 1 million centipoise.

 The polyorganohydrogensiloxane of component (B) used in the present invention is cross-linked by addition reaction with (A) component to make the composition into a rubber elastic body or gel, so 3 per molecule. As described above, each key atom is an essential component having one or less hydrogen atoms bonded to one key atom. The organic group bonded to the silicon atom other than the hydrogen atom is a group selected from the group consisting of an alkyl group, a phenyl group, and a 3,3,3-trifluoropropyl group. From the viewpoint of easy synthesis, A methyl group is most preferred. In this polyorganohydrogen siloxane, the siloxane skeleton may be linear, branched or cyclic. In addition, such SiH groups may be at the end of the polysiloxane chain or in the middle. Is preferred. The polyorganohydrogen siloxane of component (B) has 0.4 to 4 hydrogen atoms bonded to the silicon atom for each alkenyl group bonded to the silicon atom in component (A). It is preferable to use in such an amount.

 The platinum component (C) used in the present invention is a hydrosilylation catalyst. As the platinum-based catalyst used here, a Lamorrow catalyst (platinum-octanol complex, US-A

473377), Ashby's catalyst (a platinum-vinyl group-containing cyclic siloxane complex, US- A 4288345). An example is a catalyst of KARLSTEST (a platinum-vinyl group-containing disiloxane complex, US-A 3814730). The blending amount of the component (C) in the present invention is a catalyst amount, and specifically, it is used in the range of 1 to 200 ppm by weight in terms of platinum atoms with respect to the component (A).

 The (D) component polydimethylsiloxane used in the present invention is a characteristic component of the present invention, and imparts excellent release properties to the silicone rubber mold and defoaming properties of the material before curing.

 The polydimethylsiloxane of component (D) is substantially linear and has at least one alkoxy group having 1 to 3 carbon atoms at both ends of the molecule. Examples of the alkoxy group include methyl, ethyl, n-propyl and isopropyl, which may be the same or different, but are preferably the same from the viewpoint of easy synthesis. The average degree of polymerization, that is, the average number of key atoms is in the range of 5 to 500, preferably in the range of 10 to 100. If the degree of polymerization is less than 5, the terminal alkoxy group will be hydrolyzed, and it will volatilize during the curing conditions and during use, so that the effects of mold release durability and defoaming will not be obtained. On the other hand, when the degree of polymerization exceeds 500, it is necessary to add a large amount of component (D), and workability is lowered.

 Such a component (D), for example, partially hydrolyzes dimethyl dialkoxy silane in the presence of the corresponding alcohol; in the presence of the corresponding dimethyl dialkoxy silane, a cyclic compound such as otatamethylcyclotetrasiloxane. Siloxane is ring-opened equilibrated; the terminal silanol group of α, ω-dihydroxypolydimethylsiloxane is alkoxylated with the corresponding alcohol; the terminal silanol group of α, ω-dihydroxypolydimethylsiloxane is Synthesis using various methods, such as reacting the corresponding dimethyldianoloxysilane, methyltrialkoxysilane, or tetraalkoxysilane to obtain polydimethylsiloxane with 1 to 3 arbitrary alkoxy groups bonded to each terminal it can.

Component (D) is added in an amount of 0.1 to 10 parts by weight, more preferably 0.2 to 5 parts by weight, based on 100 parts by weight of polyorganosiloxane of component (D). 0. If less than 1 part by weight, the effect of sustaining mold release durability and defoaming cannot be obtained, exceeding 10 parts by weight As a result, the physical strength of the silicone rubber decreases.

The composition of the present invention preferably contains a scavenging filler. Such fillers may be those conventionally used for silicone rubber, and examples thereof include powdered silica and carbon black. Examples of fine powder silica include fumed silica and precipitated silica. In particular, the specific surface area is 50 m ² Z g or more, preferably rather is 100 to 400 m ² Z g or more of finely divided silica are preferred. If it is less than 50 m ² / g, sufficient reinforcement cannot be obtained. The amount of these fillers used is within the range of 10 to L00 parts by weight per 100 parts by weight of component (A), and if necessary, surface treated with organosilane, organosilazane, etc. May be.

 In addition to the above-mentioned components, the composition of the present invention has good storage stability at room temperature and maintains an appropriate curing time. In order to maintain an appropriate curing time, methylvinylpolysiloxane, acetylene alcohols, benzotriazole, triphenyl phosphite It is desirable to add reaction inhibitors such as organic phosphorus compounds, various triazine compounds, and organic sulfur compounds. The addition amount of this reaction inhibitor is preferably in the range of 1 to 2000 mol per 1 mol of platinum atom in the platinum-based catalyst, although it depends on the inhibitory ability of various inhibitors, and the curing rate and storage of the resulting composition From the viewpoint of stability, a ratio of 10 to 1000 moles is preferable. If necessary, suitable pigments, dyes, adhesion aids, fungicides, heat resistance improvers, flame retardants or antioxidants can be added.

In the composition of the present invention, a compound base was produced by mixing (A) component and reinforcing silica in a known mixer such as a single mixer and a loss mixer, followed by heat treatment and uniform mixing. Thereafter, if necessary, the components (B), (C), and (D) can be easily produced by uniformly mixing them with a mixer. In order to increase the fluidity of the composition, a filler surface treatment agent such as organosilazane can be blended when the component (A) and the reinforcing silica are mixed in the production of the base compound. The mold master of the present invention can be obtained by molding and curing the silicone rubber composition with a predetermined mold according to a conventional method. In this case, the curing condition of the silicone rubber composition is generally performed around the temperature at which the resin is cured for the purpose of alleviating the shrinkage at the time of curing of the resin used for the replicated product. Usually, it can be carried out at a temperature of 40 to 60 ° C. for about 2 to 20 hours. This mold master can be used effectively for the molding of resin moldings such as epoxy resins and urethane resins. Example

 EXAMPLES Hereinafter, the present invention will be described with reference to examples, but the scope of the present invention is not limited to these examples. In Examples and Comparative Examples, all parts represent weight parts.

Example 1

(A) Dimethylpolysiloxane blocked with vinyldimethylsilicone groups at both ends (viscosity ⁷ 000 cP, vinyl number 0.OO ⁷ mol ZlOO g) Hydrophobic fumed silica with specific surface area of about SAOm ² / "g in δθ part (Aerosil R-976, made by Nippon Aerosil Co., Ltd.) Mix 20 parts with a kneader, add 6 parts of hexamethyldisilazane and 1 part of water while stirring well, and mix for 1 hour without heating. Then, the temperature was raised to 150 ° C., followed by mixing for 2 hours, and then the temperature was lowered to room temperature.

 To 100 parts of the base compound thus obtained, 0 part of (C) chloroplatinic acid-vinylcyclohexane complex (platinum concentration 2 wt%), 0.05 part of tetramethyltetrabutylsiloxane siloxane, (Β ) 3 parts of methyl hydrodiene polysiloxane (see average formula below) was added and mixed until uniform to prepare a composition.

この糸且成物 100部に対し、 （D)末端ェトキシ基ポリジメチルシロキサン （粘 度 50cSt) 0. 5部を加え、 本発明の型取り母型用シリコーンゴム組成物を調製 した。 かかる型取り母型用シリコーンゴム組成物を良く攪拌した後、 真空脱泡を行 い、 型に流し込み、 4 0 °C X 1 2時間で硬化させ、 凹状の母型を作成し、 以下 の評価を行った。

0.5 parts of (D) terminal ethoxy group polydimethylsiloxane (viscosity 50 cSt) was added to 100 parts of this yarn composition to prepare a silicone rubber composition for a mold master of the present invention. After thoroughly stirring the silicone rubber composition for mold making mother mold, vacuum defoaming is performed, and the mold is poured into a mold and cured at 40 ° CX12 for 2 hours to create a concave mold, and the following evaluation is performed. went.

 (Releasability of casting resin)

 Epoxy resin-102 (manufactured by Nippon Polyurethane Co., Ltd.) is cast into the above mold, cured at 70 ° CX for 2 hours, and the following criteria are used to remove the resulting epoxy resin from the mold: Judged by.

 ○: Light

 Δ: Slightly heavy

 X: Heavy

 (Transparent casting resin turbidity)

 The turbidity of the transparent epoxy resin taken out from the matrix was evaluated by visual observation.

 (Muddy mold)

 The turbidity of the concave matrix was evaluated by visual observation.

 (Expansion volume magnification of foam)

 Silicone rubber composition for mold master, immediately after stirring for 10 minutes, 20 ml was weighed into a 300 ml 1 disc and immediately deaerated with a vacuum pump. Then, the volume of the most expanded foam was measured, and the magnification with respect to the initial volume was obtained.

 These results are shown in Table 1.

Examples 2 to 5, Comparative Examples 1 to 1 2

 When the amount of terminal ethoxy group polydimethylsiloxane (viscosity 50cSt) is changed as shown in Table 1, the amount shown in Table 1 instead of terminal ethoxy group polydimethylsiloxane (viscosity 50cSt) is shown in Table 1. A silicone rubber composition for a mold master was obtained and evaluated in the same manner as in Example 1 except that it was blended. These results are shown in Table 1.

From the results shown in Table 1, the cured product obtained from the composition according to the method of the present invention has a good releasability from the well-cast resin, and the material before curing has a good defatting property. Foam was observed

比較例 3 比較例 4 比較例 5 比較例 6 比較例 7 比較例 11 比較例^ 配合

Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Comparative Example 11 Comparative Example ^ Formulation

Addition-reaction type liquid silicone rubber composition 100 100 100 100 100 100 100 Terminal ethoxy group polydimethylpolysiloxane, viscosity 50 _c St

Terminal ethoxy group polydimethylpolysiloxane, viscosity 700cSt

End: t-oxypolydimethylpolysiloxane, viscosity 1 McSt

End :! : Toxigenic polydimethylpolysiloxane, viscosity 7McSt

 5 mol% phenyl-modified polydimethylsiloxane, viscosity 25 ° C: l OOcs,

 Three

(Refractive index 25 ° C: 1.428)

Terminal trimethylsilyl group polydimethylpolysiloxane, viscosity 25 ° C: 10OOOcs 1 5

Terminal trimethylsilyl group polydimethylpolysiloxane, viscosity 25 ° C: 100cs 3 5

Surfactant (Poly (oxyethylene) alkyl ether) 0.01 0.1 Characterization

Casting resin releasability OXO 厶 厶 XX Transparent casting resin turbidity y No No Yes No No No No turbidity of mother mold No No No No No No No A Defoamability (foam expansion volume ratio) / times 12 12 13 9 9 6 5 Viscosity / Pa.s 56 60 5F 42 30 88 180

Claims

The scope of the claims 1 · (A) having two or more alkenyl groups bonded to a silicon atom in one molecule; Viscosity at 50 to: Polyorganosiloxane with 1 million centipoise; 100 parts by weight  (B) Polyorganohydrogensiloxane having 3 or more hydrogen atoms bonded to a key atom in one molecule; (A) Bonded to a key atom for one alkenyl group bonded to a key atom in component (A) Amount of 0.4 to 4 hydrogen atoms (C) platinum-based compound; (A) component is 1 to 200 ppm by weight in terms of platinum atom  (D) a polydimethylsiloxane having an alkoxy group having 1 to 3 carbon atoms bonded to a silicon atom at the molecular end and having an average degree of polymerization of 5 to 500; 0 · 1 to 10 parts by weight A silicone rubber composition for a molding mother mold, comprising:  2. A mold master made of a cured product of the silicone rubber composition according to claim 1.