JPH0663967A - Production of porous silicone gel sheet and mold used therefor - Google Patents

Abstract

PURPOSE:To prevent the formation of a stripe pattern due to pulsation by adapting a mold whose flat surface part is subjected to grinding finish when a silicone gel raw soln. is cast in a mold to be cured under heating and, after demolding, the soluble particles in the molded one is dissolved to produce a porous sheet. CONSTITUTION:A porous silicone gel sheet is produced by a method wherein a silicone gel raw soln. having salt 2 dispersed therein as soluble particles is cast in a mold 10 wherein an edge part 12 is formed around a flat surface part 13 to be cured under heating and, after demolding, the salt 2 is dissolved in a solvent. In this method, the surface of the flat surface part 13 of the mold 10 is subjected to grinding finish. Since the surface of the flat surface part 13 of the mold 10 is subjected to grinding finish, the salt 2 dispersed in the silicone gel raw soln. 3 can uniformly flow along with the silicone gel raw soln. so as to slide on the flat surface part 13.

Description

Detailed Description of the Invention

[0001]

[Object of the Invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a porous silicone gel sheet and a mold used in that case.

[0002]

BACKGROUND OF THE INVENTION Porous silicone gel products are being used in a wide variety of products including exercise equipment such as inner soles of athletic shoes because of their excellent shock absorbing performance. As one of the molding methods for such a part made of a porous silicone gel product, a method of producing a porous silicone gel sheet (hereinafter referred to as a porous gel sheet) and die-cutting the porous gel sheet. There is. in this way,
After filling the silicone gel stock solution containing soluble granules with a slight excess in a substantially flat mold with edges, cover the top with a silicone gel stock solution and spread it over all corners of the mold. The silicone gel is heated and cured in a state where the silicone gel stock solution is overflowed, and after the mold is removed, the soluble particles are eluted in water to produce a porous gel sheet.

However, since soluble granules are dispersed in the silicone gel stock solution, if the surface condition of the mold is poor, when the silicone gel stock solution is evenly spread in the mold, the state shown in FIG.
As shown in FIG. 11A, pulsation is generated, and a striped pattern as shown in FIG. 11B is formed. If the porous gel sheet is manufactured in this state, the uniformity of the sheet strength cannot be maintained, uneven hardness may occur in places, and the appearance may be deteriorated.

[0004]

[Technical Items Attempted to Develop] The present invention has been made in view of such a background, and when a silicone gel stock solution in which soluble particles are dispersed is uniformly spread in a mold, a smooth flow is generated. Thus, the inventors have attempted to develop a method for producing a porous gel sheet which has been surface-treated and a die for producing the same.

[0005]

[Constitution of the invention]

[Means for Achieving the Object] That is, the method for producing a porous silicone gel sheet according to the first invention of the present application is to pour a silicone gel stock solution in which soluble particles are dispersed into a mold having an edge formed around a flat surface. In this state, the silicone gel stock solution is heat-cured to remove the mold, and then the soluble granules are dissolved in a solvent to manufacture a porous sheet. It is characterized by applying the thing.

In the mold for producing a porous silicone gel sheet according to the second invention of the present application, the silicone gel stock solution in which soluble particles are dispersed is poured into the mold, and the silicone gel stock solution is heated and cured in this state. In a die to be formed into a sheet shape, the die is characterized in that an edge portion is formed around a flat surface portion, and a surface of the flat surface portion is polished and finished. The above objects are achieved by these inventions.

[0007]

In the present invention, since the surface of the flat surface is polished and finished, when the silicone gel stock solution is uniformly spread in the mold, the soluble granules also smoothly flow with the silicone gel stock solution, which causes pulsation. The occurrence of a striped pattern is prevented.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to illustrated embodiments. First, before describing the present invention, the presumed silicone gel will be explained, and then the method of the present invention for producing the porous gel sheet 1 using the silicone gel will be explained, and the porosity of the present invention will be described therein. The mold for producing the silicone gel will also be described.

First, the silicone gel has, for example, the following formula [1]:
A diorganopolysiloxane (hereinafter referred to as component A) which is a stock solution of a silicone gel represented by: RR ¹ ₂ SiO— (R ² ₂ SiO) nSiR ¹ ₂ R ... [1] [wherein R is an alkenyl group and R ¹ Is a monovalent hydrocarbon group having no aliphatic unsaturated bond, R ² is a monovalent aliphatic hydrocarbon group (at least 50 mol% of R ²
Is a methyl group, and when it has an alkenyl group, its content is 10 mol% or less), and n is the viscosity of this component at 25 ° C. is 100 to 100,000 cSt.
The viscosity at 25 ° C is 50
00cSt or less and at least 2 S in one molecule
Organohydrogenpolysiloxane (B) which is a stock solution of a silicone gel having a hydrogen atom directly bonded to an i atom.
Component) and the ratio (molar ratio) of the total amount of alkenyl groups contained in the component A to the total amount of hydrogen atoms directly bonded to the Si atoms in the component B is 0.1.
It is an addition reaction type silicone copolymer obtained by curing a mixture adjusted to 2.0.

The silicone gel will be described in more detail. The component A has a linear molecular structure, and alkenyl groups R at both ends of the molecule are added to hydrogen atoms directly bonded to Si atoms in component B. And a compound capable of forming a crosslinked structure. The alkenyl group present at the terminal of this molecule is preferably a lower alkenyl group, and a vinyl group is particularly preferable in view of reactivity. R ^{1 at the} terminal of the molecule is a monovalent hydrocarbon group having no aliphatic unsaturated bond, and specific examples of such a group include an alkyl group such as a methyl group, a propyl group and a hexyl group. , Phenyl groups and fluoroalkyl groups.

In the above formula [1], R ² is a monovalent aliphatic hydrocarbon, and specific examples of such a group include:
Examples thereof include alkyl groups such as methyl group, propyl group and hexyl group, and lower alkenyl groups such as vinyl group. However, at least 50 mol% of R ² is a methyl group, when R ² is an alkenyl group is preferably an alkenyl group is the amount of 10 mol% or less. If the amount of alkenyl groups exceeds 10 mol%, the crosslink density becomes too high and the viscosity tends to be high. Also, n is
The viscosity of this A component at 25 ° C. is usually 100 to 10
20,000 cSt, preferably 200-20,000 cSt
It is set to be within the range of St.

The above-mentioned component B is a cross-linking agent for the component A and S
The hydrogen atom directly bonded to the i atom adds to the alkenyl group in the A component to cure the A component. The component B has only to have the above-mentioned action, and as the component B, those having various molecular structures such as linear, branched, cyclic, or network can be used. In addition to the hydrogen atom, an organic group is bonded to the Si atom in component B, and this organic group is usually a lower alkyl group such as a methyl group. further,
The viscosity of component B at 25 ° C. is usually 5000 cSt or less, preferably 500 cSt or less.

Examples of such component B include organohydrogenpolysiloxanes whose both ends are blocked with triorganosiloxy groups, copolymers of diorganosiloxanes and organohydrogensiloxanes, and tetraorganotetrahydrogen. Cyclotetrasiloxane, a copolymer polysiloxane composed of HR ¹ ₂ SiO 1/2 units and SiO 4/2 units, and HR ¹ ₂ SiO 1/2 units, R ¹ ₃ SiO 1/2 units and SiO 4/2 The copolymer polysiloxane which consists of a unit can be mentioned. However, in the above formula, R ¹ has the same meaning as described above. And above B
The ratio of the total molar amount of alkenyl groups in the component A to the total molar amount of hydrogen atoms directly bonded to Si in the component is usually 0.1 to 2.0, preferably 0.1 to 1.0. It is manufactured by mixing the component A and the component B so as to be within the range of and curing.

The curing reaction in this case is usually carried out using a catalyst. As the catalyst used here, a platinum-based catalyst is suitable, and as this example, finely divided elemental platinum,
Examples thereof include chloroplatinic acid, platinum oxide, a complex salt of platinum and an olefin, platinum alcoholate, and a complex salt of chloroplatinic acid and vinylsiloxane. Such complex salts consist of A component and B
It is usually used in an amount of 0.1 ppm (platinum equivalent, the same applies below) or more, preferably 0.5 ppm or more based on the total weight of the components. The upper limit of the amount of such a catalyst is not particularly limited, but, for example, when the catalyst is in a liquid state or can be used as a solution, 200 p
An amount of pm or less is sufficient.

Then, the above-mentioned components A, B and the catalyst are mixed and left to stand at room temperature or heated to cure to form the silicone gel used in the present invention. When curing by heating, the heating temperature is usually 50.
~ 160 ° C. The silicone gel thus obtained has a JIS (K2207-1980, 50 g load)
The penetration value measured in 1. is usually 5 to 250. The hardness of such a silicone gel varies depending on the cross-linking structure formed by the A component and the B component. The viscosity of the silicone gel before curing and the penetration after curing are adjusted by adding in advance a silicone oil having methyl groups at both ends in an amount within the range of 5 to 75% by weight based on the obtained silicone gel. can do.

As described above, the silicone gel can be prepared as described above, or a commercially available one can be used. Examples of commercially available products that can be used in the present invention include CF5027, TOUGH-
3, TOUGH-4, TOUGH-5, TOUGH-
6, TOUGH-7, TOUGH-8 (manufactured by Toray Dow Corning Silicone) and X32-902 / cat1
300, KE1308 / cat1300-L4 (manufactured by Shin-Etsu Chemical Co., Ltd.), F250-121 (manufactured by Nippon Unica Co., Ltd.) and the like.

In addition to the components A and B and the catalyst described above, pigments, curing retardants, flame retardants, conductive fillers and the like may be added within a range that does not impair the properties of the silicone gel. In order to improve vibration and buffering properties, a silicone gel mixed with a filler of minute hollow spheres may be used. Such filler material may be Philite (registered trademark) manufactured by Nippon Philite Co., Ltd. Pancel (registered trademark) Matsumoto Microsphere (manufactured and sold by Matsumoto Yushi-Seiyaku Co., Ltd.) can be exemplified.

Next, a method for producing the porous gel sheet 1 using such a silicone gel will be described. First, in the present invention, in order to obtain the porous gel sheet 1, soluble granules are mixed into a silicone gel stock solution and cured, and then the granules are eluted in a solvent to form pores.
And when the solvent is water, as soluble granules sodium polyacrylate, polyvinyl alcohol, methylcellulose, carboxymethylcellulose, polyethylene oxide, polyvinylpyrrolidone, amide acrylate, glue, gelatin, casein, polypeptide, funori, agar, Sodium alginate, sodium chloride, glucose, sucrose, natural polysaccharides pullulan, xanthan gum, starch, sodium ascorbate, etc. can be selected, and when acetone, ethanol, methanol, etc. can be used as a solvent, polyvinyl alcohol, methyl Cellulose, ethyl cellulose, water-soluble nylon, shellac, styrene and the like can be selected as the soluble granules.

Here, an example in which water is used as a solvent and salt is a soluble granular material will be described. 1. Mixing of raw materials First, as shown in FIG. 1, in addition to agents A and B and a catalyst of silicone gel, if necessary, pigments and the like are mixed to prepare a silicone gel stock solution 3 and salt 2 is further mixed into it. Knead well. It should be noted that if the mixing state of the silicone gel stock solution 3 and the salt 2 is poor, it will affect the quality of the product, so these should be kneaded well before use. Here, salt, particularly commercially available salt, was used as the granules, because the salt has a uniform particle size, its eluate waste liquid is relatively easy to treat, is relatively inexpensive, and elutes relatively. Because it can be done easily.

2. Filling of Raw Material First, a mold 10 according to the present invention is prepared and set in a vulcanizing press 16. As shown in FIG. 3, the mold 10 includes a rectangular aluminum flat plate 11 and a rectangular bar-shaped edge portion 1 around the rectangular aluminum flat plate 11.
2 is provided, and the flat surface portion 1 is provided on the upper surface side of the flat plate 11.
3 is formed, and a filling portion is formed in the space surrounded by the flat surface portion 13 and the edge portion 12.

The present invention is characterized by the flat surface portion 13 in such a mold 10. That is, the flat portion 13
Is subjected to a polishing treatment to improve the flow of the silicone gel stock solution 3 in which salt is dispersed. The degree of polishing depends on the particle size of the soluble particles,
Polishing with # 400 to # 600 sandpaper is preferable. If the sandpaper is too fine, a problem that a skin layer is formed on a cured sheet will be caused as described later. If the upper lid is also polished in the same manner, the mold 1
The flow of the silicone gel stock solution 3 can be improved even if it is not about zero.

Further, as shown in FIG. 3, longitudinal slits 14 are formed at the four corners of the edge portion 12 of the mold 10 as an example. The meaning and variation of the slit 14 will be described later.

The silicone gel stock solution 3 in which salt is dispersed is slightly overfilled in the filling portion of the mold 10. At this time, when the mold 10 has a substantially square shape,
As shown in FIG. 4 (a), the center is piled up in a mountain shape, and from there,
When the silicone gel stock solution 3 is filled in a star shape that extends to each corner as shown in (b), the silicone gel stock solution 3 should spread evenly along the shape of the mold 10 when the upper lid is covered. You can

3. Setting of Upper Lid After the silicone gel stock solution 3 has been filled in the mold 10, the upper lid 15 is covered flat and pressure is applied by the vulcanizing press 16 as shown in FIG. As a result, the silicone gel undiluted solution 3 flows on the flat surface portion 13 and is evenly spread to every corner of the mold 10. At this time, in the present invention, since the flat portion 13 is subjected to the polishing treatment, the salt 2 dispersed in the silicone gel stock solution 3 is also the silicone gel stock solution 3 as shown in FIGS.
At the same time, the flat surface portion 13 slips and flows uniformly, and a striped pattern due to pulsation as shown in FIG. 11 is not formed.

When pressure is continuously applied to the upper lid 15, as shown in FIG.
As shown in FIG. 4, the excess silicone gel stock solution 3 flows out from each slit 14 formed in the edge portion 12. By the way, the slit 14 is provided in this way, and the excess silicone gel stock solution 3 is made to flow out from here if the slit 1
If 4 is not formed, the excess silicone gel stock solution 3 flows out from between the upper side of the edge 12 and the upper lid 15. At this time, the salt 2 stays near the edge 12 as shown in FIG. Resulting in. Therefore, salt 2 was made to flow out from the slit 14 together with the silicone gel stock solution 3 to prevent the salt 2 from staying near the edge portion 12.

The number of slits 14 formed for such purpose is not particularly limited as long as the dispersed salt 2 can flow out together with the silicone gel stock solution. Since the gel is slightly submerged in the undiluted solution, the slit 14 is formed in the vertical direction from the same level as the flat surface portion 13 to the upper portion as in the present embodiment.
Is preferably formed.

The position of the slit 14 may be a corner or a side portion, and depending on how the silicone gel stock solution 3 is filled, the edge where the silicone gel stock solution 3 spreads most slowly when the upper lid 15 is covered. If it is provided at the portion 12, the excess silicone gel stock solution 3 and the excess salt 2 can be poured out after the silicone gel stock solution 3 has spread over the entire mold.

Further, the size of the slit 14 needs to be large enough to allow salt to flow out together with the silicone gel stock solution 3. However, when a relatively large slit 14 is provided, when excess silicone gel stock solution 3 flows out, It is necessary to provide a stopper or the like to prevent the silicone gel stock solution 3 from further flowing out. The term “slit” includes all cross-sectional shapes sufficient for the silicone gel stock solution 3 to flow out.

4. Heat curing of silicone gel After the upper lid 15 was set on the mold 10, the silicone gel stock solution 3 was cured by heating and pressurizing in the vulcanizing press 16 in this state as shown in FIG. The silicone gel 17 is used.

5. Release and Desalination After cooling, the upper lid 15 is removed, and the cured silicone gel 17 is released from the mold 10 as shown in FIG. Then salt 2
In order to facilitate the elution, the cured silicone gel is rubbed and loosened as shown in FIG. 10 (a) so that the space occupied by the adjacent salt 2 particles is continuously formed. Then, as shown in FIG. 10 (b), the salt 2 is dissolved by immersing it in water, and most of the salt 2 is eluted by using a washing machine or carefully rubbing it by hand. At this time, the flat portion 1
If 3 is mirror-finished, a skin layer is formed on the cured silicone gel sheet, and desalting treatment becomes difficult. Therefore, it is not necessary to polish the flat surface portion 13 to mirror finish. Further, as a final desalting treatment, a jet water stream is applied as shown in FIG.
As shown in (d), the porous gel sheet 1 is completed by drying in a blast drying oven. In addition, this porous gel sheet 1
By punching into a suitable shape, a part made of porous silicone gel can be obtained.

[0031]

In the present invention, since the surface of the flat surface portion 13 of the mold 10 is polished and finished, the silicone gel stock solution 3 is used.
The salt 2 dispersed in the solution uniformly flows along with the silicone gel stock solution 3 as it slides on the flat surface portion 13, and the formation of a striped pattern due to pulsation is prevented.

[Brief description of drawings]

FIG. 1 is a side view showing how raw materials are mixed.

FIG. 2 is a vertical cross-sectional side view showing a state of filling the mold of the present invention with the raw material.

FIG. 3 is an exploded perspective view showing a mold of the present invention.

FIG. 4 is a vertical cross-sectional side view and a plan view showing the same raw material filling method.

FIG. 5 is a vertical cross-sectional side view showing a state in which an upper lid is set on a mold filled with raw materials and pressed by a vulcanizing press.

FIG. 6 is a perspective view showing a state in which excess silicone gel stock solution is discharged together with excess stock solution of silicone gel from the slit during pressurization.

FIG. 7 is a skeletal side view showing a state where a silicone gel stock solution filled in a mold of the present invention flows toward an edge by being pressed and a porous gel sheet molded by the mold. FIG.

FIG. 8 is a side view showing a state where the silicone gel stock solution filled in the mold is heated and pressed by a vulcanizing press.

FIG. 9 is a perspective view showing a state in which the silicone gel cured by the vulcanizing press is released from the mold.

FIG. 10 is a perspective view showing stepwise steps of dissolving salt from the released silicone gel and completing a porous gel sheet.

FIG. 11 is a skeletal vertical sectional side view showing a problem when a mold having a poor surface condition is used, and a plan view showing a porous gel sheet molded by the mold.

FIG. 12 is a skeletal vertical cross-sectional side view showing a problem when a slit is not provided in a mold and a plan view showing a porous gel sheet molded by the mold.

[Explanation of symbols]

 1 Porous Gel Sheet 2 Salt 3 Silicone Gel Stock Solution 10 Mold 11 Flat Plate 12 Edge 13 Flat Surface 14 Slit 15 Upper Lid 16 Vulcanizing Press 17 Silicone Gel

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Claims (2)

[Claims] 1. A silicone gel stock solution in which soluble granules are dispersed is poured into a mold having an edge formed around a flat surface,
In this state, the silicone gel stock solution is heat-cured and released from the mold, and then the soluble granules are dissolved in a solvent to produce a porous sheet. A method for producing a porous silicone gel sheet, which comprises applying 2. A mold in which a silicone gel stock solution in which soluble particles are dispersed is poured into a mold, and the silicone gel stock solution is heated and cured in this state to form a sheet, wherein the mold is around a flat portion. A mold for producing a porous silicone gel sheet, characterized in that an edge portion is formed and a surface of the flat portion is polished and finished.