JP2022045154A - Silicone molded body, silicone composite body, and production method of silicone molded body - Google Patents

Abstract

To provide a silicone molded body of small thickness change and excellent durability by reducing the content of cyclic siloxane of a low molecular weight derived from silicone.MEANS FOR ACHIEVING THE PURPOSE: A silicone molded body containing cyclic siloxane has a content of the cyclic siloxane of 4-20 units of 7,400 mass ppm or less in the silicone molded body.SELECTED DRAWING: None

Description

INDUSTRIAL APPLICABILITY The present invention is used as various mold release materials used for molding display / touch panel related product members, LED lighting product members, motion / biological function measurement members, etc., such as ICs, passive components, semiconductors, etc. incorporated in electric / electronic products. The present invention relates to a silicone molded body, a silicone composite, and a method for producing a silicone molded body that can be suitably used.

Silicone typified by silicone rubber and silicone resin, especially silicone rubber such as mirable type, have excellent heat resistance and electrical properties, so they have traditionally been referred to as mold release materials and non-slip materials (hereinafter referred to as "sealing materials"). ), Etc. have been used.

However, if a sheet made of a single piece of silicone such as silicone rubber is to be used as it is as a mold release material for press molding, it will be deformed because it is a rubber product, and the assembly dimensional accuracy will deteriorate or wrinkles will occur. , There was a problem with workability.
Therefore, in order to solve the above-mentioned problems, it has been studied to compositely integrate the silicone rubber alone and the plastic film. As a result, in addition to workability such as wrinkles and adhesion, a long complex can be easily obtained, which can be used for efficient roll-to-roll production.

As one method of compounding, a method of compounding a pre-crosslinked silicone rubber unit and a plastic film via an adhesive, a method of laminating double-sided tape or applying an adhesive, etc., is used to compound them via an adhesive layer. There is a way to do it. In this case, an adhesive or adhesive for silicone rubber is usually used, but it is necessary to apply the adhesive or adhesive separately, which increases the processing cost and makes it difficult to obtain a long composite. There was an inconvenience.

Further, in order to solve such inconvenience, it has been studied to apply a silicone-based primer to a plastic film, attach a silicone uncrosslinked rubber, and then heat-crosslink the plastic film and at the same time integrate it with the silicone rubber. However, when the plastic film contains a polyester resin as a main component, the adhesiveness between the silicone-based primer and the plastic film is poor, and problems such as peeling easily occur in the obtained composite.

Further, when the plastic film has low heat resistance, heat is applied at the time of cross-linking the silicone rubber, so that it cannot be applied. Further, since the difference in thermal expansion between the plastic film and the silicone rubber is large, there is a problem that the obtained composite is curled.
In addition, since the thickness accuracy is not sufficient, when the plastic film is loaded or accumulated in a roll shape, wrinkles and bends occur as the accumulated amount increases, and the plastic film does not return to its original shape, so that it can be used as a mold release material. It was sometimes difficult to use.

As a silicone rubber composite that can solve the above-mentioned problems, in Patent Document 1, at least one side of a film containing a polyester resin as a main component has a high affinity for an undercoat layer and an undercoat layer and contains a silicone resin. There has been proposed a silicone rubber composite in which thin film layers are formed in order, a silicone rubber layer made of a silicone elastomer resin having a specific hardness is formed, and the film and the silicone rubber layer are integrated.

Japanese Unexamined Patent Publication No. 11-20082

However, when the silicone rubber composite of Patent Document 1 is repeatedly used as a release material for press molding related to electrical and electronic product members, the thickness of the silicone composite changes depending on the conditions, and the cushioning property as a release material is sufficient. In some cases, it may not be maintained or the number of times of repeated use may be limited, and concrete improvement has been desired.
In addition, silicones such as silicone rubber contain cyclic siloxanes, but the 4 to 6 merits of cyclic siloxanes (D4 to 6siloxanes) are listed in the 19th SVHC (Substances of Very High Concern) List of the European REACH Regulation and are high. Since it has been designated as a substance of very high concern, a silicone having a lower molecular weight cyclic siloxane content is desired. Then, during press molding of the electric / electronic product member, the cyclic siloxane may adhere to the electric / electronic product member, contaminating the contacts of the conductive portion and causing poor continuity.
Further, even if the content of D4 to 6siloxane is reduced, when it is repeatedly used under high temperature and pressure such as press molding, the molecular weight is relatively high, specifically, a 7 to 20-mer cyclic siloxane (D7). It is also studied by the present inventors that bleeding of ~ 20siloxane) may adhere to the molded product during a process such as press molding, and such a molded product may cause a problem in use as an actual product. Revealed by.

The present invention has been made under such circumstances, and is a silicone molded body, a silicone composite, which can reduce the content of low molecular weight cyclic siloxane derived from silicone, has a small change in thickness, and has excellent durability. The purpose is to provide a method for producing a silicone molded product.

As a result of diligent studies, the present inventors have been able to reduce low molecular weight cyclic siloxanes, and by reducing cyclic siloxanes in this way, surprisingly, thickness changes are suppressed and silicone molding with excellent durability is achieved. We have succeeded in obtaining a body and a silicone complex using the same body, and have completed the present invention.

That is, the present invention provides the following [1] to [23].
[1] In a silicone molded product containing a cyclic siloxane, the content of 4 to 20 mer of the cyclic siloxane in the silicone molded product is 7400 mass ppm or less.
[2] The silicone molded product according to [1], wherein the content of the pentamer of cyclic siloxane in the silicone molded product is 700 mass ppm or less.
[3] The silicone molded product according to [1] or [2], wherein the content of the 7 to 20-mer of cyclic siloxane in the silicone molded product is 6400 mass ppm or less.
[4] The silicone molded product according to any one of [1] to [3], wherein the content of the 10 to 20-mer of the cyclic siloxane in the silicone molded product is 5300 mass ppm or less.
[5] The silicone molded product according to any one of [1] to [4], wherein the content of the 12 to 20-mer of the cyclic siloxane in the silicone molded product is 4600 mass ppm or less.
[6] The silicone molded product according to any one of [1] to [5], wherein the content of the cyclic siloxane in the silicone molded product is 3300 mass ppm or less.
[7] The silicone molded product according to any one of [1] to [6], wherein the content of 17 to 20-mer of cyclic siloxane in the silicone molded product is 2100 mass ppm or less.
[8] The silicone molded product according to any one of [1] to [7], which contains a silicone elastomer resin.
[9] The silicone molded product according to any one of [1] to [8], which is used for any of press molding, vacuum forming, and compressed air molding.
[10] The silicone molded product according to any one of [1] to [9], which is used as a mold release material, a cushioning material or a non-slip material in molding.
[11] A silicone composite obtained by laminating a base material layer on at least one surface of the silicone molded product according to any one of [1] to [10].
[12] A silicone complex having a base material layer on at least one surface of a silicone molded body containing a cyclic siloxane, wherein the content of 15 to 20 mer of the cyclic siloxane in the silicone complex is 2330 mass ppm. The following is a silicone complex.
[13] The silicone complex according to [12], wherein the content of the 17 to 20-mer of the cyclic siloxane in the silicone complex is 1530 mass ppm or less.
[14] The silicone composite according to any one of [11] to [13], wherein the base material layer contains a polyester resin.
[15] The silicone composite according to any one of [12] to [14], wherein the silicone molded product contains a silicone elastomer resin.
[16] The silicone composite according to any one of [11] to [15], which is used for any of press molding, vacuum forming, and compressed air molding.
[17] The silicone composite according to any one of [11] to [16], which is used as a mold release material, a cushioning material or a non-slip material in molding.
[18] A carrier film containing the silicone molded product according to any one of [1] to [10] or the silicone composite according to any one of [11] to [17].
[19] A protective film containing the silicone molded product according to any one of [1] to [10] or the silicone composite according to any one of [11] to [17].
[20] A method for producing a silicone molded product, comprising a step of applying a heat treatment to uncrosslinked silicone and a step of subjecting the crosslinked silicone.
[21] A step of molding uncrosslinked silicone into a plate shape to form a plate-shaped molded product, a step of heat-treating the plate-shaped molded product, and plasticizing the plate-shaped molded product after the heat treatment. The method for producing a silicone molded article according to [20], comprising a step of extruding into a post-film or sheet shape and a step of subjecting the obtained film or sheet to a cross-linking treatment.
[22] The method for producing a silicone molded product according to [21], wherein the plate-shaped molded product has a thickness of 10 mm or less.
[23] The method for producing a silicone molded product according to any one of [20] to [22], wherein the temperature of the heat treatment in the step of performing the heat treatment is 100 to 280 ° C.

According to the present invention, it is possible to provide a silicone molded article having a small thickness change and excellent durability by reducing the low molecular weight cyclic siloxane, and a silicone complex using the same.

Hereinafter, examples of embodiments of the present invention will be described, but the present invention is not limited to the embodiments described below as long as the gist thereof is not exceeded.

The term "main component" in the present invention includes the meaning of allowing other components to be contained within a range that does not interfere with the function of the main component, unless otherwise specified.
At this time, the content ratio of the main component is not specified, but the main component (when two or more components have the same content ratio, the total amount thereof) is 50% by mass or more, preferably 50% by mass or more in the composition. It occupies 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, and particularly preferably 90% by mass or more (including 100% by mass).

In the present invention, the "cyclic siloxane" refers to a compound having a cyclic molecular structure skeleton due to a siloxane bond. Generally, it refers to a cyclic dimethyl type having a dimethylsiloxane unit in which a silicon atom having two methyl groups on a silicon atom is bonded to an oxygen atom, but the present invention is not limited to this, and a hydrogen atom other than the methyl group or an ethyl group is used. It also includes those in which a silicon atom having such a group is bonded to an oxygen atom.

Further, in the present invention, when expressed as "X to Y" (X and Y are arbitrary numbers), unless otherwise specified, it means "X or more and Y or less", and "preferably larger than X" and "preferably larger than X". Is smaller than Y ".
Further, in the present invention, when expressed as "X or more" (X is an arbitrary number), it includes the meaning of "preferably larger than X" unless otherwise specified, and "Y or less" (Y is an arbitrary number). ) Includes the meaning of "preferably smaller than Y" unless otherwise specified.

Furthermore, "sheet" generally refers to a product that is thin by definition in JIS and whose thickness is small and flat for length and width, and "film" generally refers to a product that is smaller in length and width. A thin, flat product having an extremely small thickness and an arbitrarily limited maximum thickness, which is usually supplied in the form of a roll (JIS K6900: 1994). However, the boundary between "sheet" and "film" is not clear, and it is not necessary to distinguish between the two in the present invention. Therefore, in the present invention, even when the term "film" is used, "sheet" is included and "sheet" is included. Even when referred to as a "sheet", it shall include a "film".

In the present invention, "mass ppm" may be simply abbreviated as "ppm".

<Silicone molded body>
A silicone molded product (hereinafter, also referred to as “main molded product”) as one embodiment of the present invention will be described.

The raw material component of the silicone molded product is not particularly limited as long as it contains silicone, but for example, it is preferable to contain silicone having a siloxane skeleton represented by the following formula (1). In the following formula (1), in addition to polydimethylsiloxane in which all Rs in the formula are methyl groups, a part of the methyl group is one of other alkyl groups, vinyl groups, phenyl groups, fluoroalkyl groups, etc. Various polydimethylsiloxanes substituted with two or more kinds can be appropriately selected. Further, n in the formula is a positive number of 1 or more, preferably 3 to 5000.

Among the above silicones, a silicone elastomer resin is preferable, and it is more preferable that the silicone elastomer resin is contained as a main component as a raw material component of the silicone molded product.
As an example of the silicone elastomer resin, a silicone elastomer resin containing polydimethylsiloxane as a main component is preferably mentioned.

It is also preferable that the polydimethylsiloxane contains a vinyl group from the viewpoint of adjusting the compression set.
When the vinyl group is contained, the content of the vinyl group with respect to the total amount of polydimethylsiloxane is preferably 0.05 to 5 mol%, more preferably 0.5 to 4 mol%, and 1 to 3 mol. % Is more preferable. When the content of the vinyl group is at least the above lower limit value, it becomes easy to adjust the crosslink density of the silicone elastomer resin, and it tends to be easy to obtain a silicone elastomer resin having a desired compression set. On the other hand, when it is at least the above upper limit value, it is preferable because the silicone elastomer resin is not excessively cured.
Further, as another means for obtaining the desired compression set, it is also preferable to select polydimethylsiloxane which does not contain a vinyl group and is mainly composed of a methyl group from the viewpoint of adjusting the cross-linking point. ..

The compression set is preferably 75% or less, more preferably 60% or less, further preferably 50% or less, particularly preferably 40% or less, and 30% or less. Is most preferable. By setting the compression set to the upper limit or less, the thickness of the silicone molded product tends to be less likely to change even after repeated use during press molding, and sufficient cushioning property is maintained and durability is excellent, which is preferable.
The compression set is based on JIS K6249: 2003, and refers to a compression set measured after being treated at 180 ° C. for 22 hours and then allowed to stand at room temperature (23 ° C.) for 30 minutes.

The raw material component of the silicone molded product preferably has a type A durometer hardness of 20 or more, more preferably 30 or more, further preferably 40 or more, particularly preferably 50 or more, and 60 or more. The above is the most preferable. Further, the type A durometer hardness is preferably 90 or less, and more preferably 85 or less. By setting the hardness of the Type A durometer to the above lower limit or higher, the thickness of the silicone molded product tends to be less likely to change even after repeated use during press molding, etc., and sufficient cushioning properties are maintained and durability is excellent. The tackiness of the surface of the silicone molded product is suppressed, and the handleability tends to be improved. On the other hand, by setting the hardness of the type A durometer to the upper limit value or less, the followability and adhesion to the pressed product at the time of press forming or the like tend to be easily improved.
The hardness of the type A durometer can be measured according to JIS K6253-3: 2012.

As a method for adjusting the hardness of the type A durometer, for example, a method for adjusting the filling amount of a filler such as silica to be blended with the raw material silicone as a reinforcing material, a method for appropriately selecting the type of the raw material silicone, specifically, a method for appropriately selecting the type of the raw material silicone. , A method of adjusting the content of the phenyl group by adopting a resin having a phenyl group and the like is preferably mentioned.

Commercially available products can also be used as such silicone elastomer resins. Examples of commercially available products include mirable silicone compounds manufactured by Shin-Etsu Chemical Co., Ltd. and mirable silicone rubber manufactured by Momentive Performance Materials.

Here, as the raw material components of the silicone molded body, in addition to reinforcing fillers such as fumed silica, precipitated silica, silica soil, and quartz powder, various processing aids, heat resistance improvers, etc., functionality as an elastomer is used. It may contain various additives to be possessed. These can be used alone or in combination of two or more.
Examples of the additive include a flame retardant-imparting agent, a heat-dissipating filler, a conductive filler and the like.

In the silicone molded product of the present invention, the content of the 4 to 20-mer of cyclic siloxane in the silicone molded product is 7400 ppm or less, preferably 7000 ppm or less, more preferably 6800 ppm or less, and 6000 ppm or less. It is more preferably present, and particularly preferably 5000 ppm or less.
By reducing the content of 4 to 20-mer, so-called low molecular weight cyclic siloxane, low molecular weight cyclic siloxane derived from silicone is precipitated during product manufacturing such as press molding, and the molding machine and the obtained molded product. It is possible to prevent it from adhering to and contaminating such as. In addition, by reducing the low molecular weight cyclic siloxane, the silicone molded product itself becomes hard, the thickness change is small even after repeated use, the cushioning property as a mold release material can be sufficiently maintained, and the durability is excellent. It becomes a thing.
The lower limit is preferably 100 ppm, more preferably 300 ppm, and even more preferably 500 ppm from the viewpoint of moldability and processability.

Further, if the silicone molded product contains a large amount of low molecular weight cyclic siloxane, for example, when used as an electric / electronic product member, the low molecular weight cyclic siloxane appears on the surface of the silicone molded product, so that subsequent wiring is performed. In processing, etc., there is a risk of contaminating the contacts of the conductive part and causing poor continuity. Specifically, when plasma called an arc is generated when the contacts of the conductive portion are opened and closed, if the silicone molded product contains a large amount of low molecular weight cyclic siloxane, it is gasified by the heat generated when the arc is generated. Molecular weight cyclic siloxane adheres to the contacts. As a result, silicone is deposited on the contact surface, which may cause conduction failure. In addition, when used as a protective film or carrier film, low molecular weight cyclic siloxane may precipitate due to heating, pressurization, etc. under the usage environment, which may adhere to the product and contaminate it.
In the silicone molded product of the present invention, since the content of the 4 to 20 dimer of the cyclic siloxane is not more than the above upper limit value, it is presumed that such problems such as contact contamination, poor continuity, and product contamination are less likely to occur. ..

The content of the pentamer of the cyclic siloxane in the silicone molded product is preferably 700 ppm or less, more preferably 550 ppm or less, further preferably 400 ppm or less, and particularly preferably 300 ppm or less. , 200 ppm or less is particularly preferable. Among the low molecular weight cyclic siloxanes, the pentamer has a low molecular weight and is particularly liable to volatilize or bleed. Therefore, by reducing this, the above-mentioned problems caused by the volatilization or bleeding of the low molecular weight cyclic siloxane are suppressed. Tend to be.

The content of the 7 to 20-mer of the cyclic siloxane in the silicone molded product is preferably 6400 ppm or less, and the content of the 10 to 20-mer of the cyclic siloxane is more preferably 5300 ppm or less, more preferably the cyclic. The content of the 12 to 20-mer of the siloxane is more preferably 4600 ppm or less, the content of the 15 to 20-mer of the cyclic siloxane is particularly preferably 3300 ppm or less, and the content of the 17 to 20-mer of the cyclic siloxane is particularly preferable. It is particularly preferable that the content is 2100 ppm or less. Among low molecular weight cyclic siloxanes, those having a large number of subunits of cyclic siloxane tend to be difficult to volatilize or bleed out, but tend to bleed after long-term use or repeated use. In this case, bleeding tends to occur. There is a tendency to suppress outs. As a result, even if it is used for a long time or repeatedly used, there is a tendency that functional deterioration due to bleeding and contamination of a molding machine, a molded product, or the like can be suppressed.

Further, the content of the 7 to 20-mer of the cyclic siloxane in the silicone molded product is more preferably 6000 ppm or less, further preferably 5300 ppm or less, particularly preferably 4700 ppm or less, and 4300 ppm or less. It is especially preferable to have.
The content of the 10 to 20-mer of the cyclic siloxane in the silicone molded product is more preferably 5000 ppm or less, further preferably 4500 ppm or less, particularly preferably 4300 ppm or less, and 4000 ppm or less. Is particularly preferred.
The content of the 12 to 20-mer of the cyclic siloxane in the silicone molded product is more preferably 4300 ppm or less, further preferably 4100 ppm or less, particularly preferably 4000 ppm or less, and 3900 ppm or less. Is particularly preferred.
The content of the 15 to 20-mer of the cyclic siloxane in the silicone molded product is more preferably 3200 ppm or less, further preferably 3100 ppm or less.

As for the content of the low molecular weight cyclic siloxane in the silicone molded body, a silicone raw material having a small content of the low molecular weight cyclic siloxane is appropriately selected, or heat treatment is performed in the process of manufacturing the silicone molded body to volatilize the low molecular weight cyclic siloxane. It can be reduced by extracting a low molecular weight cyclic siloxane with a solvent such as acetone, or by rolling kneading, trimix kneading, planetary kneading, etc. under reduced pressure / vacuum.

The thickness of the silicone molded product may be appropriately selected depending on the intended use, but is preferably 3 mm or less, more preferably 1 mm or less, further preferably 800 μm or less, and particularly preferably 600 μm or less. , 400 μm or less is particularly preferable. Further, from the viewpoint of appropriate elasticity, long-term use and repeated use, the lower limit is preferably 10 μm, more preferably 30 μm, further preferably 50 μm, and particularly preferably 80 μm. ..

^The T _2H of 1H contained in the silicone molded product is preferably 56 ms or less, more preferably 55.5 ms or less, further preferably 55 ms or less, and 54.5 ms or less. Is particularly preferable, and 54 ms or less is particularly preferable. The lower limit is preferably 50 ms. T _2H can be evaluated for relatively large molecular motion and can be used as a standard index for cross-linking of molecules and softness of resin. The longer the time, the higher the molecular motion and the softer it is. Since the T _2H time of this molded product is short, it indicates that it is hard, and as a result, it can be seen that the thickness change is small and the durability tends to be excellent.
The T _2H is obtained by measuring T _2H ( ¹ H spin-spin relaxation time) by the spin echo method using solid-state NMR.

<Manufacturing method of silicone molded product>
The method for producing the silicone molded product is not particularly limited, but when a crosslinkable silicone raw material is used, a step of heat-treating the uncrosslinked silicone (hereinafter referred to as “heat treatment step”) and a cross-linking treatment are performed. It is preferable to include a step of applying (hereinafter, referred to as “crosslinking treatment step”). It is more preferable to go through the cross-linking treatment step after the heat treatment step because the heat treatment can be performed at one time at the stage of the uncrosslinked silicone raw material and the step can be shortened. Further, the step of molding the uncrosslinked silicone raw material into a silicone molded product (hereinafter referred to as “molding step”) may be performed before or after the heat treatment step, but the effect of reducing low molecular weight cyclic siloxane is large. It is more preferable to carry out the cross-linking treatment after passing through the molding step after the heat treatment step. The process will be specifically described below.

In the present invention, it is preferable to have the heat treatment step. Since the low molecular weight cyclic siloxane is volatilized by the heat treatment, the content of the low molecular weight cyclic siloxane in the obtained silicone molded product is reduced.

The stage of performing the heat treatment is not particularly limited. The uncrosslinked silicone may be heat-treated in advance and then the silicone molded product may be molded, or the uncrosslinked silicone molded product may be first molded and then heat-treated. From the viewpoint of the effect of reducing siloxane, it is preferable to heat-treat the uncrosslinked silicone in advance and then mold the silicone molded product.

In the heat treatment step, the uncrosslinked silicone raw material may be heat-treated as it is, but it is possible to heat-treat the plate-shaped or the like after once molding it into a plate-like shape or the like. It is preferable from the viewpoint of reducing the cyclic siloxane. The thickness of the uncrosslinked plate-like molded product (before heat treatment) is preferably 10 mm or less, more preferably 6 mm or less, further preferably 5 mm or less, and 4 mm or less. Is particularly preferable, and 3.5 mm or less is particularly preferable. With the above thickness, the low molecular weight cyclic siloxane is volatilized, and the content of the low molecular weight cyclic siloxane in the obtained silicone molded product tends to be more easily reduced. Further, from the viewpoint of handleability and processing amount, the lower limit is preferably 0.5 mm, more preferably 1 mm.

The heating temperature in the heat treatment step is preferably 100 to 280 ° C, more preferably 130 to 250 ° C, and even more preferably 160 to 230 ° C. Within the above range, the silicone is less likely to deteriorate, and the content of the low molecular weight cyclic siloxane in the silicone molded product tends to be further reduced.

The heating time in the heat treatment step is preferably 0.1 to 30 hours, more preferably 0.3 to 20 hours, further preferably 0.5 to 10 hours, and particularly preferably 1 to 9 hours. .5-8 hours is most preferred. Within the above range, the silicone is less likely to deteriorate, and the content of the low molecular weight cyclic siloxane in the silicone molded product tends to be effectively reduced.

In the molding step, the uncrosslinked silicone raw material is molded into an uncrosslinked silicone molded product by extrusion molding, injection molding, calendar molding, press molding or the like. In the heat treatment step, when the silicone raw material is once molded into a plate-like shape and heated, the plate-like molded product after the heat treatment is plasticized by roll kneading, trimix kneading, planetary kneading, or the like. After that, it is preferable to mold the silicone molded product again. The shape of the molded body is not particularly limited, but it is preferably molded into a film or sheet from the viewpoint of productivity and processability such as when forming a silicone composite described later.

Next, in the cross-linking treatment step, the silicone molded product of the present invention can be obtained by cross-linking the uncross-linked silicone raw material. As a means for cross-linking silicone, a curing catalyst, a curing agent, a cross-linking agent, etc. are added in advance to the silicone raw material to be used, and the material is cured by light such as heat or ultraviolet rays, moisture in the air, etc., or cross-linked by irradiation. The method and the like can be mentioned.

Among them, the silicone molded product is preferably a radiation-cured product cured by irradiation. Curing by irradiation is preferable because there is no concern that the heat resistance and light resistance will be impaired by the residue of the catalyst or the cross-linking agent.

Examples of radiation include electron beams, X-rays, γ-rays, and the like. These radiations are also widely used industrially, are readily available and are energy efficient methods. Among them, it is preferable to use γ-rays from the viewpoint of almost no absorption loss and high transparency.

The irradiation dose of γ-rays can be appropriately selected and determined depending on the type of resin, the amount of cross-linking groups, and the type of radiation source. In the present molded product, for example, the irradiation dose of γ-rays is preferably 20 to 150 kGy, more preferably 30 to 120 kGy, further preferably 40 to 110 kGy, and more preferably 50 to 100 kGy. Especially preferable. When the irradiation dose is at least the above lower limit value, the silicone molded product can be sufficiently crosslinked, and as a result, the desired compression set and durometer hardness tend to be easily obtained. On the other hand, when the irradiation dose is not more than the upper limit value, there is a tendency that the increase of the low molecular weight cyclic siloxane component due to the decomposition reaction can be suppressed.

In the present invention, from the viewpoint of achieving both the effect of reducing low molecular weight cyclic siloxane and productivity, a step of molding an uncrosslinked silicone raw material into a plate shape to form a plate-shaped molded body and heating the plate-shaped molded body. The step of applying the treatment, the step of plasticizing the plate-shaped molded product after the heat treatment and then extruding it into a film or sheet, and the step of subjecting the obtained film or sheet to a crosslinking treatment are performed. It is particularly preferable to prepare in this order.

<Silicone complex>
Next, as another embodiment of the present invention, a silicone complex using the silicone molded product (hereinafter, also referred to as “the present complex”) will be described.

Since this composite has a base material layer laminated on at least one surface of the silicone molded body, wrinkles and bending are unlikely to occur, and when used as a mold release material for, for example, press molding, vacuum forming, pressure molding, etc. Productivity of articles is improved.

The content of the 15 to 20-mer of the cyclic siloxane in the silicone complex is 2330 ppm or less, preferably 2300 ppm or less, more preferably 2270 ppm or less, still more preferably 2250 ppm or less. It is particularly preferably 2230 ppm or less. The content of the 17 to 20-mer of the cyclic siloxane is preferably 1530 ppm or less, more preferably 1510 ppm or less.
Among low molecular weight cyclic siloxanes, those having a large number of subunits of cyclic siloxane tend to be difficult to volatilize or bleed out, but tend to bleed after long-term use or repeated use. In this case, bleeding tends to occur. Out can be suppressed. As a result, for example, even if it is repeatedly used as a cushioning material for press molding, functional deterioration due to bleeding and contamination of the molded product can be suppressed.
The lower limit is preferably 100 ppm, more preferably 300 ppm, and even more preferably 500 ppm from the viewpoint of moldability and processability.

For the content of the low molecular weight cyclic siloxane in the silicone composite, a silicone raw material having a small content of the low molecular weight cyclic siloxane is appropriately selected, or heat treatment is performed in the process of producing the silicone molded product or the silicone composite to reduce the molecular weight. It can be reduced by volatilizing the cyclic siloxane, extracting the low molecular weight cyclic siloxane with a solvent such as acetone, or performing roll kneading, trimix kneading, planetary kneading, etc. under reduced pressure / vacuum.

The thickness of the silicone complex may be appropriately selected depending on the intended use, but is preferably 5 mm or less, more preferably 3 mm or less, further preferably 1.5 mm or less, and preferably 1 mm or less. It is particularly preferable, and it is particularly preferable that it is 800 μm or less. Further, from the viewpoint that appropriate elasticity can be easily obtained and the handleability is good, the lower limit is preferably 30 μm, more preferably 50 μm, further preferably 100 μm, and particularly preferably 150 μm. ..

Regarding the change in the thickness of the silicone complex by pressing by the following measuring method, it is preferably 4.4 μm or less, more preferably 4.1 μm or less, and 3.8 μm or less from the viewpoint of durability. It is more preferably 3.6 μm or less, and particularly preferably 3.6 μm or less.

As a method for measuring the thickness change, a press machine (manufactured by Imoto Seisakusho Co., Ltd., trade name BIGHEART) is used under the conditions of room temperature (23 ° C.) and a press pressure of 500 kg / cm ² , and the thickness before pressing and after pressing three times. A method of measuring each thickness and calculating the thickness change according to the following formula can be mentioned. The number of samples is 2 or more, and the average value thereof is calculated as the value of the thickness change.
[Equation] | T ₃ -T ₀ |
T ₀ : Thickness before pressing T ₃ : Thickness after pressing 3 times

^The 1H T _2H contained in the silicone molded product of the silicone complex is preferably 56 ms or less, more preferably 55.5 ms or less, still more preferably 55 ms or less, and 54.5 ms. The following is particularly preferable, and 54 ms or less is particularly preferable. The lower limit is preferably 50 ms. T _2H can be evaluated for relatively large molecular motion and can be used as a standard index for cross-linking of molecules and softness of resin. The longer the time, the higher the molecular motion and the softer it is. Since the T _2H time of this complex is short, it indicates that it is hard, and as a result, it can be seen that the thickness change is small and the durability tends to be excellent.
The T _2H is obtained by measuring T _2H ( ¹ H spin-spin relaxation time) by the spin echo method using solid-state NMR.

[Silicone molded body (silicone layer)]
The present composite contains a silicone molded body (silicone layer) and a base material layer, and the raw material of the silicone molded body (silicone layer) is the same as the silicone molded body of the present invention described above. Is used.

[Base layer]
The material of the base material layer is not particularly limited, but for example, an olefin resin, a styrene resin, a polyester resin, a polycarbonate resin, a polyamide resin, a polyetherimide resin, a polyphenylene sulfide resin, and a polyphenylene ether. Examples thereof include resins, polyaryl ether ketone resins, liquid crystal polymer resins, and polyimide resins. From the viewpoint of heat resistance and mechanical strength, it is preferable to contain a polyester resin, and it is more preferable to contain the polyester resin as a main component.

Among the polyester resins, it is preferable to use a crystalline polyester resin, and examples of the crystalline polyester resin include polyethylene terephthalate and polyethylene naphthalate. Of these, polyethylene terephthalate is preferable from the viewpoint of heat resistance, film strain, smoothness, availability for commercial use, and adhesion to the silicone layer. These can be used alone or in combination of two or more.

Further, the base material layer may contain additives such as ultraviolet absorbers, light stabilizers, antioxidants, plasticizers, nucleating agents, lubricants, pigments and dyes as long as the effects of the present invention are not impaired. .. From the viewpoint of mechanical strength, it is preferably stretched to at least one axis, and more preferably to two axes.

The thickness of the base material layer is preferably 10 to 350 μm, more preferably 15 to 300 μm, still more preferably 20 to 250 μm. By setting the thickness to the lower limit or more, the generation of wrinkles and the like tends to be sufficiently suppressed when the silicone layer or other layers are laminated on the surface. On the other hand, when the value is not more than the upper limit, the base material layer does not become too hard, so that it tends to be easy to apply the undercoat layer or the like described later.

Further, in the present composite, it is preferable to provide an undercoat layer and / or a thin film layer between the base material layer and the silicone molded body, and the layer structure of the silicone composite is such that the base material layer / undercoat layer / thin film layer is provided. / Silicone molded body (silicone layer) is laminated in this order and integrated. For convenience, the base material layer will be described below as the A layer, the undercoat layer as the B layer, the thin film layer as the C layer, and the silicone molded product (silicone layer) as the D layer.

[Undercoat layer (B layer)]
The undercoat layer (B layer) preferably contains an amorphous polymer, more preferably contains an amorphous polymer as a main component, and is provided on one side of the base material layer (A layer). By using the undercoat layer (B layer), the thin film layer (C layer) tends to be formed uniformly.

The amorphous polymer is not particularly limited as long as it can be uniformly applied to the base material layer (A layer), and is substantially limited to polyurethane resin, acrylic resin, amorphous polyester resin and the like. It may be appropriately selected from non-crystalline polymers. These can be used alone or in combination of two or more.
Specific examples include a polyurethane resin obtained by linearly polymerizing a polyester resin and / or a polyether resin by a urethane bond or the like, an acrylic resin composed of a copolymer of acrylic acid and / or a methacrylate ester, an acid component, or glycol. Examples thereof include a copolymerized polyester resin having two or more kinds of monomers. Since these amorphous polymers are coated to form a thin film, they are usually diluted with an organic solvent or emulsified or solubilized in water to adjust the concentration to an appropriate level.

The undercoat layer (B layer) may have a crosslinked structure for the purpose of improving heat resistance and solvent resistance. In this case, the amorphous polymer has a carboxy group in the main chain or side chain. It has a crosslinkable functional group such as a hydroxyl group and an amino group, and the crosslinking agent is timely selected from polyisocyanate, melamine, polyfunctional epoxy resin, metal compound and the like. Further, in addition to the cross-linking agent, a leveling agent made of a surfactant or the like, a blocking inhibitor such as silica, a thickener or the like may be added to the coating liquid. These can be used alone or in combination of two or more.

The thickness of the undercoat layer (B layer) is preferably 0.01 to 5 μm, more preferably 0.05 to 4 μm, and even more preferably 0.1 to 3 μm.
When the thickness of the undercoat layer (B layer) is at least the above lower limit value, the thickness can be easily adjusted, and the adhesiveness with the thin film layer (C layer) described later is likely to be good, which is preferable. Further, when the thickness is not more than the upper limit value, the undercoat layer (B layer) can be easily coated, which is preferable.

[Thin film layer (C layer)]
The thin film layer (C layer) is further provided on the undercoat layer (B layer). The thin film layer (C layer) preferably contains a silicone resin, and more preferably contains a silicone resin as a main component. Among them, it has a high affinity for the undercoat layer (B layer) and is heated after coating. Alternatively, those that form a crosslinked film by UV irradiation or the like, or those that form a crosslinked film at the same time as crosslinking the silicone layer (D layer) are particularly preferable.

Examples of the silicone resin that can be used for the thin film layer (C layer) include an addition type silicone resin, a condensation type silicone resin, a UV curable silicone resin, and the like, and among them, the condensation type silicone resin is the effect of the present invention. Is preferable because it can be effectively obtained. These can be used alone or in combination of two or more.

Examples of the addition type silicone resin include those obtained by using polydimethylsiloxane containing a vinyl group as a base polymer, blending polymethylhydrogensiloxane as a cross-linking agent, and reaction-curing in the presence of a platinum catalyst.
Examples of the condensed silicone resin include those obtained by using polydimethylsiloxane containing a silanol group at the terminal as a base polymer, blending polymethylhydrogensiloxane as a cross-linking agent, and heat-curing in the presence of an organotin catalyst. ..
The UV curable silicone resin includes a polydimethylsiloxane containing an acryloyl group or a methacryloyl group as a base polymer, a polydimethylsiloxane containing a mercapto group and a vinyl group as a base polymer, and the above-mentioned addition type silicone resin. Alternatively, a photopolymerization initiator may be added to a polydimethylsiloxane-based polymer containing an epoxy group that is cured by a cationic curing mechanism, and the polymer may be cured by irradiating with UV light.

Further, the thin film layer (C layer) preferably contains an additive such as a silane coupling agent for the purpose of increasing the affinity with the undercoat layer (B layer). The silane coupling agent satisfying this purpose is a compound represented by the general formula YRSiX ₃ , where Y is an organic functional group such as a vinyl group, an epoxy group, an amino group and a mercapto group, and R is an alkylene such as methylene, ethylene and propylene. Group and X are hydrolyzable functional groups such as methoxy group and ethoxy group or alkyl groups.

Examples of the silane coupling agent include vinyltriethoxysilane, vinyltrimethoxysilane, γ-glycidylpropyltrimethoxysilane, γ-glycidylpropyltriethoxysilane, and N-β (aminoethyl) -γ-aminopropyltrimethoxysilane. , N-β (aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane and the like. These can be used alone or in combination of two or more.

The thickness of the thin film layer (C layer) is preferably 0.01 to 1 μm, more preferably 0.03 to 0.7 μm, still more preferably 0.05 to 0.5 μm after solvent drying. When the thickness is at least the above lower limit value, a cured film having a uniform thickness can be obtained, and a sufficient adhesive force with the silicone layer (D layer) tends to be obtained. Further, since the silicone resin having the thin film layer (C layer) composition is generally not so strong in film strength, cohesive fracture tends to occur in the thin film layer (C layer) when evaluating the peeling force of the composite. When the thickness is not more than the upper limit value, the thin film layer (C layer) tends to be suppressed from coagulation and fracture, and sufficient strength as a silicone composite tends to be easily obtained.

[Laminated structure]
In the laminated structure of the silicone complex of the present invention, the A layer and the D layer are indispensable, but as described above, the A layer / B layer / C layer / D layer are laminated in this order and integrated. Is preferable. Further, a layer other than the B layer and the C layer may exist between the A layer and the D layer. If necessary, another layer such as a protective layer may be laminated on the surface of the silicone layer (D layer).
Further, if antistatic performance is required, an antistatic layer may be laminated on the outermost surface of the complex. The antistatic layer is preferably laminated on the surface opposite to the side on which the D layer of the A layer is laminated.

<Manufacturing method of silicone complex>
The method for producing the silicone composite of the present invention is not particularly limited as long as the base material layer (A layer) can be laminated on at least one surface of the silicone molded product (D layer), and the laminating method is known. Method can be used.

For example, a base material layer (A layer) may be prepared, a silicone layer (D layer) may be prepared separately from the base material layer (A layer), and these may be laminated, or a base material layer (A layer) may be prepared and the base material layer may be prepared. A silicone layer (D layer) may be formed on the (A layer) and laminated and integrated. On the contrary, a silicone layer (D layer) may be formed, and a base material layer (A layer) may be formed on the silicone layer (D layer). ), And may be laminated and integrated, or the base material layer (A layer) and the silicone layer (D layer) may be laminated and integrated.

Examples of the step of producing the base material layer (A layer) and the silicone layer (D layer) include a method of melt-kneading a raw material resin and extruding it with a single-screw or twin-screw extruder.
The base material layer (A layer) and the silicone layer (D layer) can be laminated by coextrusion, extrusion laminating, thermal laminating, dry laminating or the like. Specifically, the base material layer (A layer) and the silicone layer (D layer) may be kneaded and co-extruded at the same time by a feed block method, a multi-manifold method, or the like to be laminated and integrated, or the base material layer (A layer). And the silicone layer (D layer) may be separately produced to obtain a base material layer (A layer) and a silicone layer (D layer), and then laminated and laminated.

In the case of coextrusion, the base material layer (A layer) and the silicone layer (D layer) can be combined with the resin through a feed block or a multi-manifold die using a plurality of extruders to prepare a laminated body. ..

In the case of extrusion laminating, the raw material of the silicone layer (D layer) is extruded from a T-die, I-die, etc. using a single-screw or twin-screw extruder, and then a roll method, a tenter method, a tubular method, etc. are used. A single layer body to be a silicone layer (D layer) is obtained. Subsequently, when the raw material of the base material layer (A layer) is extruded from a T-die, an I-die, etc. using a single-screw or twin-screw extruder, it is laminated on the silicone layer (D layer) at the same time as casting. This complex can be obtained.

In the case of thermal laminating and dry laminating, the raw material of the silicone layer (D layer) is extruded from a T-die, I-die, etc. using a single-screw or twin-screw extruder to obtain a single-layer body to be the silicone layer (D layer). .. Further, a base material layer (layer A) is prepared by using the same method. Subsequently, the base material layer (A) and the silicone layer (D layer) can be laminated by arranging an adhesive layer or the like under heating or between layers to obtain the present complex.

Among them, from a base material layer (A layer) / undercoat layer (B layer) / thin film layer (C layer) / silicone molded body (silicone layer) (D layer), which is a preferable example of a method for producing a silicone composite. The method for producing the silicone composite will be described below.

First, at least one surface of the above-mentioned base material layer (A layer) is coated with a coating liquid as an undercoat layer (B layer), then dried, and further heat-crosslinked as necessary to cause an undercoat layer (B). Layer) is formed. As the coating method, a known method suitable for the coating liquid can be applied, and the substrate layer (A layer) stretched in another step may be coated, or the substrate layer (A layer) may not be stretched. The sheet may be directly coated with a coating liquid and then stretched to form an undercoat layer (B layer). Further, the coated surface of the base material layer (layer A) may be subjected to surface treatment such as corona treatment in advance for the purpose of improving the leveling property and adhesion of the coating liquid.

Next, a thin film layer (C layer) is applied on the undercoat layer (B layer). The coating method is not particularly limited as long as it is a method for obtaining a thin film with high accuracy, as in the case of the undercoat layer (B layer), but it is preferable to use a bar coater from the viewpoint of accuracy.

Further, the silicone layer (D layer) is preferably laminated by the following method. First, the uncrosslinked silicone raw material is laminated on the thin film layer (C layer). As a laminating method, an uncrosslinked silicone raw material (for example, a silicone elastomer resin) is molded into a film or sheet by extrusion molding, injection molding, calendar molding, press molding, etc., and then on the thin film layer (C layer). However, it is more preferable from the viewpoint of productivity to adopt the above-mentioned methods such as extrusion laminating, thermal laminating, and dry laminating. Further, a method of directly forming a film on the thin film layer (C layer) by a known coating method may be used.

In the present invention, when a crosslinkable silicone raw material is used, it is preferable to heat-treat the uncrosslinked silicone raw material. By heat-treating the uncrosslinked silicone raw material, the low molecular weight cyclic siloxane contained in the silicone is volatilized, so that the content of the low molecular weight cyclic siloxane in the obtained silicone complex tends to be easily reduced.

The stage of heat-treating the silicone raw material is not particularly limited. The silicone raw material may be heat-treated in advance to form a silicone layer (D layer) on the thin film layer (C layer), or uncrosslinked silicone formed from the silicone raw material into a film or sheet. The film or sheet may be heat-treated and then laminated on the thin film layer (C layer), or the silicone layer (D layer) may be laminated on the thin film layer (C layer) to form a silicone composite. After the production, heat treatment may be performed. Among them, it is preferable to heat-treat the uncrosslinked silicone raw material and then laminate it on the thin film layer (C layer) to form a complex because the effect of reducing the low molecular weight cyclic siloxane is large.

In the heat treatment, the uncrosslinked silicone raw material may be heat-treated as it is, but it is possible to heat-treat the plate-shaped or the like after once forming it into a plate-like shape or the like. It is preferable from the viewpoint of reducing siloxane. The thickness of the uncrosslinked plate-like molded product (before heat treatment) is preferably 10 mm or less, more preferably 6 mm or less, further preferably 5 mm or less, and 4 mm or less. Is particularly preferable, and 3.5 mm or less is particularly preferable. With the above thickness, the low molecular weight cyclic siloxane is volatilized, and the content of the low molecular weight cyclic siloxane in the obtained silicone complex tends to be more easily reduced. Further, from the viewpoint of handleability and processing amount, the lower limit is preferably 0.5 mm, more preferably 1 mm.

In the heat treatment, the heating temperature is preferably 100 to 280 ° C, more preferably 150 to 250 ° C, and even more preferably 160 to 230 ° C. Within the above range, the silicone is less likely to deteriorate, and the content of the low molecular weight cyclic siloxane in the silicone complex tends to be further reduced.

In the heat treatment, the heating time is preferably 0.1 to 30 hours, more preferably 0.3 to 20 hours, further preferably 0.5 to 10 hours, and particularly preferably 1 to 9 hours. .5-8 hours is most preferred. Within the above range, the silicone is less likely to deteriorate, and the content of the low molecular weight cyclic siloxane in the silicone complex tends to be effectively reduced.

Next, using the uncrosslinked silicone raw material, a silicone composite is produced by laminating and molding by the above method, and further, the silicone is crosslinked and cured to obtain the silicone composite of the present invention. .. In the heat treatment, when the silicone raw material is once molded into a plate-like shape and heated, the plate-like molded product after the heat treatment is plasticized by a method such as roll kneading, trimix kneading, or planetary kneading. After that, it is preferable to mold the silicone composite. As a means for cross-linking / curing silicone, a curing catalyst, a curing agent, a cross-linking agent, etc. are added in advance to the silicone raw material to be used, and the silicone is cured by light such as heat or ultraviolet rays, moisture in the air, etc., or by irradiation. Examples include a method of cross-linking.

Above all, the silicone layer (D layer) in this complex is preferably a radiation-cured product cured by irradiation. Curing by irradiation is preferable because there is no concern that the heat resistance and light resistance will be impaired by the residue of the catalyst or the cross-linking agent. Further, since the thin film layer (C layer) and the silicone layer (D layer) have sufficient adhesion, the defect of delamination can be suppressed, which is preferable.

Examples of radiation include electron beams, X-rays, γ-rays, and the like. These radiations are also widely used industrially, are readily available and are energy efficient methods. Among them, it is preferable to use γ-rays from the viewpoint of almost no absorption loss and high transparency.

The irradiation dose of γ-rays can be appropriately selected and determined depending on the type of resin, the amount of cross-linking groups, and the type of radiation source. In the present complex, for example, the irradiation dose of γ-rays is preferably 20 to 150 kGy, more preferably 30 to 120 kGy, further preferably 40 to 110 kGy, and more preferably 50 to 100 kGy. Especially preferable. When the irradiation dose is at least the above lower limit value, the silicone layer (D layer) can be sufficiently cured, and as a result, the desired compression set and durometer hardness tend to be easily obtained. On the other hand, when the irradiation dose is not more than the upper limit value, there is a tendency that the increase of the low molecular weight cyclic siloxane component due to the decomposition reaction can be suppressed.

Further, in selecting the irradiation dose, it is necessary to consider not only the crosslink density of the silicone elastomer resin but also the radiation resistance of the plastic film used as the base material layer (layer A). In this respect, a crystalline polyester resin can be mentioned as a material of the base material layer (layer A) which is generally excellent in resistance to radiation and which is extremely suitable for the object of the present invention.

<Use>
The silicone molded body (single layer) or silicone composite of the present invention reduces the content of low molecular weight cyclic siloxane derived from silicone and is excellent in reducing the change in thickness. Therefore, in the case of silicone, particularly silicone rubber, its characteristics ( It can be used for various purposes by taking advantage of its appropriate adhesion to parts and followability). For example, various manufacturing processes, especially mold release materials such as press molding, vacuum forming, and pressure forming, cushioning materials, non-slip materials (sealing materials), carrier films and protective films for transporting and protecting workpieces, liquid crystal displays and frames. It can be used as a fixing material, an interlayer filling material between a liquid crystal panel and a protective panel, a bonding material for a touch panel, and the like.
Among them, it can be suitably used as a press molding such as hydraulic / hydraulic press molding, a mold release material such as vacuum forming and pressure forming, a carrier film, and a protective film. For example, it is suitably used as a mold release material, a cushioning material, and a non-slip material when molding a molded product such as a display / touch panel related product member such as an IC, a semiconductor, or a passive component incorporated in an electric / electronic product, or an LED lighting product member. Can be done.
In particular, in press molding, it is more preferably used because it is not easily deformed even if it is used repeatedly.

Hereinafter, examples will be described, but the present invention is not limited thereto.

<Example 1>
1. 1. Heat treatment of silicone raw materials While rolling kneading a miraculous silicone elastomer resin (KE-581-U, Type A Durometer Hardness 80, manufactured by Shin-Etsu Chemical Co., Ltd.) with a roll mill (Mixing Roll Mill, manufactured by Inoue Seisakusho Co., Ltd.). It was taken into a plate shape to prepare a plate-shaped molded body of an uncrosslinked silicone elastomer resin having a thickness of 3 mm.
The plate-shaped molded product was heat-treated at 200 ° C. for 5 hours (2.5 hours twice (front and back)) using an oven (constant temperature / cooling device ONDO) manufactured by Temperature Equipment Research Institute). As a result, the low molecular weight cyclic siloxane was volatilized to obtain a silicone elastomer resin molded product of the decyclic siloxane.
Next, the silicone elastomer resin molded product of the decyclic siloxane was plasticized by subjecting it to roll kneading again under the same conditions as described above.

2. 2. Production of Silicone Composite By the method shown below, a laminate of a base material layer, an undercoat layer, a thin film layer, and an uncrosslinked silicone molded body (silicone layer) was prepared and crosslinked to obtain a silicone composite. ..

[Base layer]
A biaxially stretched polyethylene terephthalate (PET) film (manufactured by Mitsubishi Chemical Corporation, Diafoil T-100, specific gravity 1.4) having a thickness of 100 μm was prepared as a base material layer and subjected to corona treatment.

[Undercoat layer]
15 parts by mass of amorphous polyester resin (Byron 240, manufactured by Toyobo Co., Ltd.) and 2 parts by mass of polyisocyanate (Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) in 85 parts by mass of solvent (methyl ethyl ketone / toluene = 1/4 (mass ratio)). It was diluted to make a coating liquid. This is applied to the corona-treated surface of the base material layer with a bar coater so that the thickness after drying becomes 1.0 μm, and the undercoat layer is dried and crosslinked at 100 ° C. for 10 minutes in an oven. Formed.

[Thin film layer]
20 parts by mass of the condensed silicone resin composition (SRX290, manufactured by Toray Dow Corning Silicone) and 1.2 parts by mass of the curing agent (SRX242C, manufactured by Toray Dow Corning Silicone) in 78.8 parts by mass of the solvent (toluene). Diluted to obtain a coating solution. This was applied to the surface of the undercoat layer with a bar coater so that the thickness after drying was 0.1 μm, and dried and crosslinked at 100 ° C. for 10 minutes in an oven to form a thin film layer.

A biaxially stretched PET film (manufactured by Mitsubishi Chemical Corporation, Dia) on the thin film layer of the laminated body composed of the prepared base material layer, undercoat layer, and thin film layer supplied along the two calendars having a diameter of 100 mm and as a cover sheet. The above-mentioned heat-treated silicone raw material is supplied between the foil T-100 and the specific gravity 1.4), and a bank is formed on the roll under the condition of a roll temperature of 80 ° C., and a base material layer, an undercoat layer, and a thin film are formed. A composite was prepared so as to be a laminated body (100 μm) composed of layers / a silicone layer (300 μm) / a cover sheet (100 μm).
The obtained composite is irradiated with γ-rays so that the absorbed dose is 50 kGy, and the silicone elastomer resin is crosslinked to integrate the laminate composed of the base material layer, the undercoat layer, and the thin film layer with the silicone elastomer resin layer. A modified composite (base material layer (A layer) / undercoat layer (B layer) / thin film layer (C layer) / silicone layer (D) / cover sheet) was obtained.
The cover sheet was peeled off from this composite to obtain a silicone composite of a base material layer (A layer) / undercoat layer (B layer) / thin film layer (C layer) / silicone layer (D) for evaluation. The thickness of the obtained silicone complex was 410.9 μm.

<Example 2>
In the heat treatment step of the silicone raw material, a silicone complex was obtained by the same method as in Example 1 except that the thickness of the plate-shaped molded product used for the heat treatment was changed to 5 mm. The thickness of the silicone complex was 409.6 μm.

<Comparative Example 1>
A silicone complex was obtained in the same manner as in Example 1 except that the silicone raw material was not heat-treated. The thickness of the silicone complex was 388.6 μm.

Measurement of various physical properties in Examples and Comparative Examples was carried out according to the following method. The results are shown in Table 1.

(1) Content of low molecular weight cyclic siloxane As an internal standard solution, 5 mg of decamethylcyclopentasiloxane (cyclic siloxane pentamer (D5siloxane)) was precisely weighed, placed in a 100 mL volumetric flask, and messed up with acetone. Was used.
2 g of the silicone complex was precisely weighed into a sample bottle, and 10 mL of the internal standard solution was weighed into the sample bottle. After covering the sample bottle with a lid, a parafilm was sprinkled on the sample bottle, and the sample bottle was immersed at a temperature of 23 ° C. for 16 hours for extraction. Then, the content of the low molecular weight cyclic siloxane was measured by gas chromatography (GC) in the acetone solution in the sample bottle under the following measurement conditions. The column temperature was maintained at 70 ° C. for 1 minute, then raised at a rate of 25 ° C./min to 320 ° C. and held for 5 minutes before measurement.

(Measurement condition)
-Measuring device: GC-2010Plus (manufactured by Shimadzu Corporation)
-Column: Ultra ALLOY Capillary Color-UA1 (MS / HT) (100% dimethylpolysiloxane, length 30 m, inner diameter 0.25 mm, film thickness 0.1 μm)
・ Carrier gas: helium ・ Flow rate: 1 mL / min ・ Detector: FID

(Calculation method of content)
Based on the internal standard amount of D5siloxane and GC peak area, each cyclic siloxane Dn was quantified from the peak area derived from each cyclic siloxane Dn (Dn is D4 to D20siloxane and has a dimethylsiloxane unit). .. For D5siloxane, the internal standard D5siloxane content was subtracted for quantification.
Since the measurement was performed on the silicone complex, the content of each cyclic siloxane in the silicone layer (D layer: silicone molded body) was the base material layer (A layer) and the silicone layer (D layer) of the composite. It was calculated using the thickness ratio of each layer and the specific gravity of each layer.

(2) Change in thickness after pressing For the silicone complex, use a press machine (BIGHEART manufactured by Imoto Seisakusho Co., Ltd.) under the conditions of room temperature (23 ° C.) and press pressure of 500 kg / cm ² , thickness before pressing, 3 times. The thickness after pressing was measured, and the thickness change was calculated according to the following formula. The number of samples was 2, and the average value of the two points was calculated as the value of the thickness change.
[Equation] | T ₃ -T ₀ |
T ₀ : Thickness before pressing T ₃ : Thickness after pressing 3 times

(3) T _2H
The ¹ H T _2H ( ¹ H spin-spin relaxation time) contained in the silicone complex was measured by the spin echo method using solid-state NMR under the following measurement conditions.

(Measurement condition)
-Measuring device: Bruker AVANCEIII 400WB
・ Probe: 4mmΦ CPMAS
・ Measurement temperature: 23 ° C
-Sample tube rotation speed: 5000 Hz
・ Observation nucleus: ¹ H (400.3 MHz)
-Pulse sequence: Spin Echo
・¹ H90 ° pulse: 4.2 μs × 1.6 dB (54 W / 300 W)
-Delay time τ: 1 μs to 100 ms
・ Pulse delay: 20s
・ Import time: 0.819s
・ Number of integrations: 1
Since the relaxation behavior is expressed by the following formula, it was calculated by curve fitting.

(4) Tensile test A dumbbell-shaped No. 2 test piece was prepared from each silicone composite, and a tensile tester (AGS-H manufactured by Shimadzu Corporation, load cell capacity 1 kN) was used in accordance with JIS K6251: 2017. A tensile test was carried out in the flow direction (longitudinal direction: MD direction) of the film under the conditions of a measurement temperature of 23 ° C., a distance between gripping tools of 30 mm, and a stroke speed of 500 mm / min, and elongation during cutting was measured.

The silicone layer (silicone molded product) and the silicone complex of the examples both have a low content of low molecular weight cyclic siloxane, which is a substance of very high concern, and the change in thickness due to press molding is suppressed, and the T _2H time is also long. It was short (hard) and had excellent durability.
Therefore, for example, when it is used as a member of an electric / electronic product, it is presumed that problems such as contact contamination, poor continuity, and product contamination are less likely to occur. It is also presumed that even if the cushioning material is repeatedly used for press molding, the change in thickness is small and the function of the cushioning material can be suppressed from deteriorating.

On the other hand, the silicone layer (silicone molded product) and the silicone complex of the comparative example have a large content of low molecular weight cyclic siloxane, a relatively large change in thickness, and a relatively long T _2H time (soft). ), It was inferior in durability.

Further, the pentamer (D5) of the cyclic siloxane is particularly easy to volatilize or bleed among the low molecular weight cyclic siloxanes, and is a standard index for measuring the content of the low molecular weight cyclic siloxane. It was found that the content of the siloxane pentamer (D5) was particularly suppressed. It is presumed that this will suppress the above-mentioned problems caused by the volatilization of the low molecular weight cyclic siloxane.

Further, those having a large number of subunits of cyclic siloxane (D17 to 20 in an extreme example) are usually difficult to volatilize or bleed among low molecular weight cyclic siloxanes, and bleed due to long-term use or repeated use. However, in the examples, it was found that the content of the cyclic siloxane having a large number of subunits was also suppressed. It is presumed that this will prevent functional deterioration due to bleeding and contamination of the molding machine, molded product, etc. even after long-term use or repeated use.

Further, in the silicone layer (silicone molded body) and the silicone composite in the examples, the low molecular weight cyclic siloxane does not bleed and unnecessary expansion and contraction is small, so that they can be used as a mold release material for press molding, a cushioning material, etc. For example, it is considered to be useful as a carrier film used for transporting and storing electronic parts such as semiconductors, flexible circuit boards, and microchips, and also as a protective film for robot arms and the like.

Since the silicone molded body or silicone composite of the present invention reduces the content of low molecular weight cyclic siloxane derived from silicone and is excellent in reducing the thickness change, various manufacturing processes, especially press molding such as hydraulic / hydraulic press molding, Mold release materials such as vacuum forming and pressure forming, cushioning materials, non-slip materials (sealing materials), carrier films such as pallets for transporting and storing electronic parts, protective films such as robot arms, liquid crystal displays and frame fixing materials, liquid crystal It can be used as an interlayer filler between a panel and a protective panel, a bonding material for a touch panel, and the like. Among them, it can be suitably used as a press molding such as hydraulic / hydraulic press molding, a mold release material such as vacuum forming and pressure forming, and a cushioning material. In particular, it is suitably used as a mold release material, a cushioning material, and a non-slip material when molding a molded product such as a display / touch panel related product member such as an IC, a semiconductor, or a passive component incorporated in an electric / electronic product or an LED lighting product member. Can be done.

Claims (23)

In a silicone molded product containing cyclic siloxane,
A silicone molded product in which the content of 4 to 20 mer of cyclic siloxane in the silicone molded product is 7400 mass ppm or less. The silicone molded product according to claim 1, wherein the content of the pentamer of cyclic siloxane in the silicone molded product is 700 mass ppm or less. The silicone molded product according to claim 1 or 2, wherein the content of the 7 to 20-mer of the cyclic siloxane in the silicone molded product is 6400 mass ppm or less. The silicone molded product according to any one of claims 1 to 3, wherein the content of the 10 to 20 dimer of the cyclic siloxane in the silicone molded product is 5300 mass ppm or less. The silicone molded product according to any one of claims 1 to 4, wherein the content of the 12 to 20-mer of the cyclic siloxane in the silicone molded product is 4600 mass ppm or less. The silicone molded product according to any one of claims 1 to 5, wherein the content of the cyclic siloxane in the silicone molded product is 3300 mass ppm or less. The silicone molded product according to any one of claims 1 to 6, wherein the content of 17 to 20 mer of cyclic siloxane in the silicone molded product is 2100 mass ppm or less. The silicone molded article according to any one of claims 1 to 7, which contains a silicone elastomer resin. The silicone molded product according to any one of claims 1 to 8, which is used for any of press molding, vacuum forming, and compressed air molding. The silicone molded product according to any one of claims 1 to 9, which is used as a mold release material, a cushioning material or a non-slip material in molding. A silicone complex obtained by laminating a base material layer on at least one surface of the silicone molded product according to any one of claims 1 to 10. A silicone complex having a base material layer on at least one surface of a silicone molded body containing a cyclic siloxane, wherein the content of 15 to 20 mer of the cyclic siloxane in the silicone complex is 2330 mass ppm or less. , Silicone complex. The silicone complex according to claim 12, wherein the content of the 17 to 20-mer of the cyclic siloxane in the silicone complex is 1530 mass ppm or less. The silicone composite according to any one of claims 11 to 13, wherein the base material layer contains a polyester resin. The silicone composite according to any one of claims 12 to 14, wherein the silicone molded product contains a silicone elastomer resin. The silicone composite according to any one of claims 11 to 15, which is used for any of press molding, vacuum forming, and compressed air forming. The silicone composite according to any one of claims 11 to 16, which is used as a mold release material, a cushioning material or a non-slip material in molding. A carrier film comprising the silicone molded product according to any one of claims 1 to 10 or the silicone composite according to any one of claims 11 to 17. A protective film comprising the silicone molded product according to any one of claims 1 to 10 or the silicone composite according to any one of claims 11 to 17. A method for producing a silicone molded product, comprising a step of applying a heat treatment to uncrosslinked silicone and a step of subjecting the crosslinked silicone. A step of molding uncrosslinked silicone into a plate shape to form a plate-shaped molded product, a step of heat-treating the plate-shaped molded product, and a process of plasticizing the plate-shaped molded product after the heat treatment to form a film. The method for producing a silicone molded article according to claim 20, further comprising a step of extruding into a sheet and a step of subjecting the obtained film or sheet to a cross-linking treatment. The method for manufacturing a silicone molded product according to claim 21, wherein the thickness of the plate-shaped molded product is 10 mm or less. The method for producing a silicone molded product according to any one of claims 20 to 22, wherein the temperature of the heat treatment in the step of performing the heat treatment is 100 to 280 ° C.