JPS6153395B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a plastic-organopolysiloxane composite foam having an adhesive layer. Currently, plastic foam is used for packing and cushioning in various devices, including technical fields such as electrical products, automobiles, and cameras, as well as for insulation, sound absorption, protection, joint sealing, etc. in houses.
Plastic foam that has been applied to gap tapes, etc., and has been given conductivity, is used for antistatic purposes in IC-related fields, medical fields, etc., for pressure-sensitive switches,
It is widely used for radio wave absorption, various sponge electrodes, etc., and in recent years, it has been required to have better weather resistance, heat resistance, durability, high elasticity, etc. On the other hand, a plastic-organopolysiloxane-based composite foam has been developed in which hardened layers of organopolysiloxane are formed on the inner and outer surfaces of a plastic foam with an open cell structure. By making appropriate selections, it is possible to create a foam that satisfies the above-mentioned properties, but since the organopolysiloxane composition is present on the surface of the foam, adhesion and adhesive treatment is difficult. It is necessary to use liquid type RTV, two-component type RTV with self-adhesive properties, or a special silicone adhesive to attach it to the equipment, and therefore workability is poor, and silicone adhesive However, the adhesive force is weak and it is not practical.
Furthermore, silicone-based double-sided pressure-sensitive adhesive tapes have the disadvantage of being expensive and not always satisfactory. The present invention relates to a method for producing a plastic-organopolysiloxane composite foam having a novel adhesive layer that solves the above-mentioned problems.
This is a plastic foam with an open-cell structure, which has an adhesive layer on one or both sides, and is made of 1 selected from low-molecular siloxanes with a boiling point of 200°C or less, liquid silanes, fluorinated hydrocarbons, and water. It is characterized by impregnating a seed or two or more media with a curable organopolysiloxane-based liquid composition in which a curable organopolysiloxane is dispersed or dissolved, and then drying and curing. The plastic-organopolysiloxane composite foam obtained by the method of the present invention is prepared by pressure-bonding a commercially available double-sided adhesive tape that has a non-silicone adhesive layer on one or both sides, or by applying an organic adhesive to a silicone-treated release paper. The adhesive layer is protected by a rubber chlorine, making it easy to attach to equipment.Also, the open-cell plastic foam has hardened organopolysiloxane layers on the inner and outer surfaces, making it weather resistant, heat resistant, and durable. It has advantages over conventional plastic foam in terms of strength, high elasticity, etc. The method of the present invention will be explained below. There are no restrictions on the material, hardness, shape, etc. of the plastic foam used in the present invention as long as it has a relatively uniform cell structure, but it is preferable that the plastic foam has continuity and flexibility. Soft polyether polyurethane foams and polyester polyurethane foams are preferred. It goes without saying that in the present invention, the plastic foam does not include one made of organopolysiloxane. The present invention uses the above-mentioned plastic foam as a base material, and provides an adhesive layer on one or both sides of the plastic foam. This can be done by applying a conventionally known adhesive that adheres well to plastic or by pasting a double-sided adhesive tape. Adopted. Usually, it is advantageous to use double-sided adhesive tape because the process can be simplified. This double-sided adhesive tape is made of a fibrous base material such as paper, woven fabric, or non-woven fabric, or a plastic film such as polyethylene, polyester, or PVC. Commercially available adhesives coated with organic adhesives such as , synthetic rubber, EVA, and epoxy are used. On the other hand, in order to form organopolysiloxane-based cured film layers on the inner and outer surfaces of a plastic foam having an open cell structure, a liquid composition of curable organopolysiloxane is used. This curable organopolysiloxane may be any material, such as one mainly composed of a diorganopolysiloxane with a linear structure or one mainly composed of an organopolysiloxane with a varnish structure, but when cured, the silicone rubber becomes elastic. A so-called silicone rubber composition is preferable. For example, polysiloxanes such as dimethylpolysiloxane, dimethylvinylpolysiloxane, dimethylvinylphenylpolysiloxane, and 3-trifluoropropylmethylvinylpolysiloxane are combined with various fillers, pigments, and functional fillers (e.g., carbon black, metal powder, etc.). It consists of a conductivity imparting agent, a magnetism imparting agent such as barium titanate, a heat conductive agent such as alumina and magnesia, a magnetic conductive flux agent such as ferrite), fiber powder, a blowing agent, a vulcanizing agent, and a catalyst, and is usually used in RTV rubber or heat. Commercially available vulcanized rubber is used. Further, a composition mainly composed of a modified organopolysiloxane obtained by radical polymerizing an olefin monomer such as an acrylic acid monomer, its ester, or styrene in a polysiloxane may be used. Among these compositions, general physical properties and various characteristics,
Even heat-vulcanized rubber and RTV rubber have high viscosity due to functionality etc.
RTV rubber and LTV rubber for LIM are preferable. On the other hand, these compositions need to be low viscosity solutions in view of workability, processability, coating/impregnating properties, etc. but,
Low viscosity liquid rubbers generally have drawbacks such as insufficient strength and difficulty in imparting various functionalities.
-It is generally used after diluting it with a general-purpose organic solvent such as an aliphatic hydrocarbon such as hexane,
There are problems such as resource saving, pollution such as environmental pollution, and problems such as swelling and deterioration of the plastic foam.In particular, the plastic foam provided with the organic adhesive layer shown in the present invention has the disadvantage that the adhesive dissolves and elutes with organic solvents. . The present invention solves these problems by using an organopolysiloxane composition with a boiling point of 200°C.
1 selected from the following low molecular weight organosiloxanes, liquid silanes, fluorinated hydrocarbons, and water.
A liquid composition is prepared by dispersing or dissolving a cured organopolysiloxane in a seed or two or more types of media, and the liquid composition is impregnated into plastic foam and subjected to hardening treatment. The low molecular weight organosiloxane or silane with a boiling point of 200°C or less used here includes, for example, the formula (In the formula, R ¹ represents a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group, and Y represents a hydroxyl group or a hydrolyzable group. a is 0<a≦4, b is 0≦b≦
4, where a+b is 0<a+b≦4), and the silanes represented by the above formula (i) include tetramethylsilane, trimethyl ethylsilane, trimethyl vinylsilane,
Trimethyl perfluoropropylsilane, trimethyl methoxysilane, trimethyl ethoxysilane, dimethyl dimethoxysilane, vinyl
trimethoxysilane, trimethylsilanol, perfluoropropyl trimethoxysilane, Or expression

Heterocyclic silane compounds represented by [Formula] are exemplified, and the siloxanes shown below are exemplified (However, in the molecular formula below, Me represents a methyl group as above, and Vi ) indicates a vinyl group). Further, examples of the fluorinated hydrocarbons include trichloride-fluorinated methane, trichloride-trifluoride ethane, and tetrachloride-difluorinated ethane. In general, there are many fluorinated hydrocarbons, ranging from high to low vapor pressures, allowing a wide range of working conditions, but considering the amount of resources and air pollution, it is preferable to use siloxane, silane, or water. . Generally, hexamethyldisiloxane has no functional groups in its molecule, is inert, and has an appropriate boiling point. is the most preferable in terms of workability, processability, evaporability, etc. On the other hand, as a liquid composition using water as a medium,
Examples include commercially available products such as Latex No. 1, MF-20, and KM-792 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), and ordinary water-soluble emulsion compositions produced by known methods. Furthermore, a mixture of siloxanes or silanes and fluorinated hydrocarbons may be used as a diluent, or a curable silicone rubber composition dissolved in such a diluent may be used as an emulsion or latex. The viscosity of the curable organopolysiloxane liquid composition using these low-molecular-weight siloxanes, silanes, fluorinated hydrocarbons, water, or mixtures thereof as a medium is at least 2% by weight of the active ingredient,
Preferably, the concentration is 20% by weight or more and the concentration at 25°C is 100,000 centipoise or less, preferably 10,000 centipoise or less. This is because if the viscosity exceeds 100,000 centipoise, it becomes difficult to sufficiently impregnate the inside of the plastic foam with an open cell structure or to coat the surface uniformly, which tends to result in non-uniform foams and processing. performance and workability become inferior. For example, the composite foam according to the present invention includes (a) a curable organopolysiloxane with a boiling point of 200°C;
A step of adjusting the processing viscosity to an optimum level or preparing a water-soluble emulsion composition by dissolving it in the following low-molecular-weight siloxanes, silanes, or fluorinated hydrocarbons; (b) on one or both sides of the plastic foam; A process of applying an adhesive layer to the plastic foam by pressure-bonding double-sided adhesive tape or applying an organic adhesive and protecting the adhesive layer with silicone-treated release paper; (c) applying a curable organopolymer to the plastic foam having the adhesive layer; It can be produced by a step of impregnating and curing the siloxane liquid composition (a) and (d) cutting or fusing the plastic-organopolysiloxane composite foam obtained in step (c) above. This method involves, for example, forming an adhesive layer on one side of a plastic foam, and then impregnating the other side with a curable organopolysiloxane-based liquid composition and drying and curing it. A desired composite foam can be created by forming a membrane layer. In this case, as a result, the adhesive layer is applied to the non-silicone-treated side, so that it is strongly adhesively integrated with the foam substrate. In addition, after forming an adhesive layer on both sides of a somewhat thick sheet-like foam, it is impregnated with a liquid composition of curable organopolysiloxane, dried and cured, and then this sheet-like material is divided into two sheet-like materials. The desired adhesive form can also be obtained by slicing. Note that dry curing after impregnating the organopolysiloxane liquid composition and then removing the medium by air drying may be carried out at room temperature if the composition cures at room temperature. A method of heating and curing at °C is advantageous in terms of increasing productivity. The accompanying drawings show a typical embodiment of the composite foam according to the present invention, in which FIG. 1 shows an adhesive layer provided on one side of the foam, and FIG. 2 shows an example in which an adhesive layer is provided on both sides of the foam. This is what happens. In the figure, 1 is a foam impregnated with organopolysiloxane, 2 is a double-sided adhesive tape with organic adhesives 4 on both sides of a base film 3, and 5
is a siliconized release paper. When storing the composite foam obtained in this way, the adhesive layer can be covered with protective paper (such as silicone release paper).
When used, the protective paper is removed and the adhesive is pressure-adhered to the desired location. The present invention is directed to the above-mentioned cellular materials having continuity and flexibility, such as plastic foams such as polyurethane, vinyl, polyolefin, ester, amide, styrene, acrylic, etc., and having continuity and porosity. It can also be applied to single-sided or double-sided adhesive composite forms made of woven or non-woven fabrics made of metal fibers, animal and plant fibers, synthetic fibers, mineral fibers, etc., impregnated with various rubbers, plastics, or solutions. Next, a specific example will be given. All parts are by weight. Example 1 A commercially available open-cell polyurethane foam sheet (density: 1.0 mm, 300 x 300 mm)
0.026, hardness 42, tensile strength 2.0 Kg/cm ² ), a commercially available double-sided acrylic adhesive tape (manufactured by SUGAWARA) was pressed and held with pinch rolls to make it adhere tightly. Next, KE1600RTV (product name, manufactured by Shin-Etsu Chemical Co., Ltd.)
A 50% by weight solution of hexamethyldisiloxane (viscosity
500 centipoise), the foam was uniformly impregnated with this liquid composition, air-dried at room temperature for 1 hour, and then heated and cured at 100° C. for 1 hour. As a result, a polyurethane foam-silicone composite foam sheet was obtained which had an adhesive layer on one side (protected with silicone release paper) and a silicone rubber film on the other surface of the foam. This composite foam without adhesive layer has a density of 0.18, hardness of 60, and tensile strength of 3.2Kg/cm ²
showed the physical properties of When this composite foam was subjected to an accelerated weathering test by irradiating it for 450 hours with a weather meter (Toyo Rika Co., Ltd. model WE-2), there was almost no material deterioration, and as shown in the table below, the weather resistance It was highly sexual. It also had excellent heat resistance and moisture resistance. On the other hand, in the impregnation treatment of the foam with a 50% by weight solution of KE1600RTV in which toluene was used instead of hexamethyldisiloxane in the above example, the polyurethane foam swelled with the toluene, and the adhesive layer swelled and dissolved. The adhesive tape has peeled off.

【table】

[Table] Example 2 A commercially available acrylic double-sided adhesive tape was adhered to the polyurethane foam sheet used in Example 1 in the same manner as in Example 1. Next, 100 parts of KE1901 (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) was dissolved in 60 parts of hexamethyldisiloxane and 140 parts of Daiflon S-3 (trade name, manufactured by Daikin Industries, Ltd.) to form a liquid composition for impregnation treatment (viscosity 1550 centipoise). ) was prepared. This liquid composition was uniformly impregnated into the foam, and after air-drying at room temperature for 1 hour,
It was heated and cured at 100°C for 1 hour. As a result, a polyurethane foam-silicone composite foam sheet was obtained which had an adhesive layer on one side (protected with silicone release paper) and a silicone rubber film on the other surface of the foam. This composite foam without an adhesive layer exhibited physical properties of density 0.15, hardness (F type) 55, and tensile strength 4.0 Kg/cm ² . When this composite foam was subjected to an accelerated weathering test by irradiating it for 450 hours with a weather meter (Toyo Rika Co., Ltd. model WE-2), there was almost no material deterioration as in Example 1, and the weather resistance was improved. It was excellent. It also had excellent heat resistance and moisture resistance. Example 3 A commercially available open-cell polyurethane foam sheet (density
0.13, tensile strength 7.5 Kg/cm ² ), a commercially available acrylic double-sided adhesive tape was adhered to one side in the same manner as in Example 1. Next, 100 parts of KE1901 used in Example 2 was added to water.
A water-soluble liquid composition (viscosity 515
centipoise) was prepared. This liquid composition was uniformly impregnated into the foam, air-dried at 60°C for 40 minutes, and then heated and cured at 100°C for 1 hour. As a result, a composite foam sheet having an adhesive layer similar to that in Example 1 was obtained, and this composite foam without an adhesive layer exhibited physical properties of a density of 0.40 and a tensile strength of 12.4 Kg/cm ^{2 .} . Example 4 A commercially available open-cell polyurethane foam sheet (density
0.03, tensile strength 1.8Kg/cm ² ), Example 1
A commercially available double-sided acrylic adhesive tape was used in the same manner as in the previous step. Next, 100 parts of the 50% by weight liquid composition of KE1600RTV hexamethyldisiloxane prepared in Example 1 was emulsified using a homogenizer with 150 parts of water and 5 parts of polyoxyethylene alkyl phenyl ether in the same manner as in Example 3 to obtain a water-soluble A liquid composition (viscosity 485 centipoise) was prepared. This liquid composition was uniformly impregnated into the foam and heated to 60°C for 1 hour.
After preheating and air drying for an hour, it was subsequently heated and cured at 100°C for 1 hour. As a result, a composite foam sheet having properties similar to those of Example 1 and having adhesive layers on both sides was obtained. This composite foam without an adhesive layer exhibited physical properties of a density of 0.10 and a tensile strength of 3.2 Kg/cm ² .

[Brief explanation of the drawing]

1 and 2 are cross-sectional views showing one embodiment of a plastic-organopolysiloxane composite foam having an adhesive layer obtained by the method of the present invention. 1...foam, 2...double-sided adhesive tape, 3...
... Base film, 4 ... Organic adhesive, 5 ... Silicone-treated release paper.

Claims (1)

[Claims] 1 A plastic foam with an open cell structure, which has an adhesive layer on one or both sides in advance, and is selected from low-molecular siloxanes with a boiling point of 200°C or less, liquid silanes, fluorinated hydrocarbons, and water 1
Impregnating a curable organopolysiloxane-based liquid composition in which a curable organopolysiloxane is dispersed or dissolved in a seed or two or more types of media,
A method for producing a plastic-organopolysiloxane composite foam having an adhesive layer, which is then dried and cured.