JPS6247454B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a compressed foam polyurethane sheet and a method for producing the same.

[Conventional technology]

Conventionally, as a means of forming a foam with a desired apparent density, a highly foamed foam is formed in advance, and then the cell skeletons constituting the foam are compressed to bring the skeletons into cross-contact and simultaneously exposed to high temperature. The contact portions are melted and fixed by heating to obtain a compressed foamed polyurethane sheet. That is,
After forming a foam with a high magnification and a low density in advance, the cell skeleton constituting the foam is destroyed by heating and compression treatment to form a foam with a low magnification and a high density.

According to such a conventional method, a foam having a desired apparent density can be arbitrarily obtained from a commercially available foam sheet having a density lower than the desired apparent density. In other words, according to this method, even without preparing from raw materials,
A foam having a desired apparent density can be obtained, and even a small amount of a foam having a desired apparent density can be obtained. Therefore, compared to the method of obtaining a foamed sheet with a desired apparent density by adjusting the formulation, reaction conditions, etc. from the raw material stage, this conventional method is economically advantageous.
Further, the apparent density of the foam sheet can be easily adjusted depending on the purpose.

Compressed polyurethane sheets obtained by this conventional method are used in a wide variety of applications, including clothing materials, cushioning materials, and sound-absorbing materials.

[Problem that the invention seeks to solve]

However, although the compressed polyurethane sheets obtained by the conventional method described above are effective in obtaining foams with relatively low apparent densities, extremely fine porous sheets (polyurethane foams with high apparent densities) There are the following problems in order to make a sheet).

That is, as the compression pressure increases during the compression process, the number of intersections between the cell skeletons constituting the foam increases from point contact to surface contact. When the areas that come into surface contact melt, the pores of the foam disappear and the foam becomes film-like. This is similar to the formation of a film when synthetic resin fibers are laminated and heated and compressed to a high strength when manufacturing a nonwoven fabric by utilizing the fusion of fiber intersections. When the pores of the foam disappear and the foam becomes film-like, the foamed structure of the polyurethane foam sheet is lost. As a result, a problem arises in that this polyurethane sheet loses its functions as a foam (characteristics such as flexibility, elasticity, air permeability, sound absorption, etc.).

On the other hand, compressed foamed urethane sheets having micropores have a wide range of applications and great needs in the fields of filter materials, cosmetic applicators, clothing materials, sound absorbing materials, cushioning materials, and the like. Therefore, it is strongly desired to solve the problems mentioned above.

As a result of various studies, the present inventor found that in order to obtain a compressed foamed polyurethane sheet with micropores, the conventional method of simply melting and immobilizing the cell skeleton constituting the foam, It has been confirmed that even if various conditions are changed, there are limits due to the above-mentioned problems.

First, the present inventor impregnated and coated the skeleton of a porous foam with a thermoplastic synthetic resin, and utilized the difference in melting point between the resin coated on the porous skeleton and the skeletal resin to foam. We proposed to fix the skeleton in a compressed state by bonding the coating layers on the surface of the skeleton to each other by compressing and heating the body. Although foams of some desired apparent density can be obtained with this method, the pore size of the foam is limited by the degree of compaction and the thickness of the coating layer.

[Purpose of the invention]

The present invention has been made in view of the above background. The purpose of the present invention is to take advantage of the manufacturing advantages of conventional compressed foam polyurethane, such as using a commercially available foam polyurethane sheet, while producing a compressed foam polyurethane sheet with micropores that cannot be obtained by conventional manufacturing methods. It is about providing. Furthermore, another object of the present invention is to provide a method for manufacturing the above-mentioned foamed polyurethane sheet.

[Means for solving problems]

According to the present invention, the skeleton of a polyurethane foam sheet with an open cell structure is in a compressed state, and there is a synthetic resin foam layer on the surface of the skeleton, and the synthetic resin foam layer mixes a foaming agent or air bubbles into the synthetic resin liquid. The above-mentioned problem can be solved by a compressed foamed polyurethane sheet, which is formed by foaming and has micropores, and the synthetic resin foam layer fixes the foamed polyurethane sheet in a compressed state. Resolved the point.

The present invention also includes a step of impregnating a foamed polyurethane sheet with an open cell structure with a synthetic resin liquid mixed with a blowing agent or air bubbles, a step of squeezing the impregnated synthetic resin liquid, and a step of drying the squeezed polyurethane sheet. step, the polyurethane sheet obtained in the above step is heated and compressed at a temperature at which the synthetic resin attached to the skeleton surface foams to form a synthetic resin foam layer, and the polyurethane sheet is compressed by the synthetic resin foam layer. The above-mentioned problem has been solved by a method for producing a compressed foamed polyurethane sheet, which is characterized by comprising a step of fixing the sheet with a polyurethane sheet.

[Effect]

According to the present invention, instead of directly melting and fixing the cytoskeleton of the foam to fix it in a compressed state,
Another foam layer is formed on the surface of the cytoskeleton, thereby securing the cytoskeleton in a compressed state.

Since the foamed layer formed on the surface of the skeleton is interposed to fix the compressed state, the flexibility of the original foamed polyurethane itself is not impaired.

Furthermore, according to the present invention, since a foam layer is formed on the surface of the skeleton, the apparent density is lower than that of a conventional compressed foam polyurethane sheet or a compressed foam polyurethane sheet produced by the method previously proposed by the inventor. The pores of the foam skeleton can be made even finer if the pores are the same. Furthermore, the bubbles in the foam layer on the surface of the skeleton are foamed by mixing a foaming agent or air into the synthetic resin liquid, so they are extremely fine compared to the pores (bubbles) between the skeletons of the original polyurethane sheet. Moreover, since it is foamed in a compressed state (pressurized state), the pores are even finer than when no pressure is applied.

To produce the compressed foamed polyurethane sheet of the present invention, first, a foamed polyurethane sheet with an open cell structure is prepared as a raw fabric, and this polyurethane sheet is impregnated with a foaming agent or a synthetic resin liquid containing fine air bubbles. This synthetic resin liquid may be either a solution type or an emulsion type.

Next, after squeezing this impregnated synthetic resin liquid,
Pre-dry the polyurethane sheet to volatilize the solvent or moisture as appropriate.

The pre-dried polyurethane sheet is then heated and compressed to a desired thickness. This heating temperature is set to a temperature at which the synthetic resin adhering to the surface of the skeleton foams. By this heating, the foaming component acts effectively to foam and solidify the synthetic resin on the skeletal surface of the raw fabric, forming a foamed layer having micropores on the skeletal surface. During this time, the raw polyurethane sheet is in a compressed state, so the air bubbles in the foam layer become smaller pores than normal (when not compressed), and when the foam layer solidifies, the foam layer causes the polyurethane sheet to become compressed. Fixed.

〔Example〕

Hereinafter, the present invention will be explained in detail based on specific examples.

Example 1 A foamed polyurethane sheet with an open cell structure having a thickness of 8 mm was impregnated with a mixed solution of the following components.

*Bonditsuku 1010C (Dainippon Ink Co., Ltd.) (component polyurethane resin emulsion) 100 parts by weight *Vinifor AZ (Eiwa Kasei Co., Ltd.) (component Azobis-
iso-butyronitrile) {(CH ₃ ) ₂ C(CH)N:
NC (CN) (CH ₃ ) ₂ } (foaming agent) 5 parts by weight * Tinuvin P (Ciba Geigy) (ultraviolet absorber) 0.4 parts by weight * Cyanox 425 (antioxidant) 0.3 parts by weight * PVM (15% liquid) 3 parts by weight * Ammonia chloride 5 parts by weight * Coagulant WS (Bayer AG) (coagulant)
1.5 parts by weight After the foamed polyurethane sheet is impregnated with the mixed solution as described above, the impregnated foamed polyurethane sheet is 200% of the weight of the foamed polyurethane sheet itself.
It was narrowed down to % by weight. Then 50℃~100
By pre-drying at ℃, the solid content in the liquid mixture was adhered to the surface of the foam skeleton of the foam polyurethane sheet. Thereafter, the polyurethane foam sheet, which was initially 8 mm thick, was compressed to a thickness of 6 mm using a hot plate heated to a plate surface temperature of 160°C.

During heating and compression, the solid matter attached to the surface of the foam skeleton is heated to a temperature that produces a foaming state and is compressed, thereby intervening between the foam skeletons of the compressed foam polyurethane sheet and forming a fine foam layer. did. The fine foam layer formed between the skeletons fixed the skeletons in a compressed state.

Example 2 A foamed polyurethane sheet with an open cell structure having a thickness of 6 mm was coated and impregnated with a mixed solution of the following components.

*Bonflex L7101 (Dainippon Ink Co., Ltd.) (component polyurethane resin emulsion) 100 parts by weight *Bonflex LN-10 (Dainippon Ink Co., Ltd.) (crosslinking agent) 15 parts by weight *Soda bicarbonate (foaming agent) 5 parts by weight* Silicone oil F-230 (foam stabilizer) 1 part by weight * 1:1 mixture of toluene and ethyl acetate 40 parts by weight A foamed polyurethane sheet coated and impregnated with the above mixture is squeezed and pre-dried at 70°C to 80°C to form a foamed skeleton. The solid content in the liquid mixture was adhered to the surface of the sample. Then, it was compressed to a thickness of 4 mm using a compression plate heated to 145°C. In this heating and compression process, the solid content on the surface of the foam skeleton took on a foamed state and was interposed between the foam skeletons. In this way, a fine foam layer could be formed on the surface of the foam skeleton of the compressed foam polyurethane sheet.

Example 3 A polyurethane foam sheet having an open cell structure and having a thickness of 8 mm was impregnated with a mixed solution of the following components.

*Bonditsuku 2010 (Dainippon Ink Co., Ltd.) (polyurethane resin emulsion) 50 parts by weight *Deiknal 1570 (Dainippon Ink Co., Ltd.) (acrylic resin emulsion) 50 parts by weight *Ammonia stearate 5 parts by weight *Ammonia oleate 2 Part by weight * Sumitex M3 (Sumitomo Chemical Co., Ltd.) 1 part by weight * Sumitex Accelerator ACX (Sumitomo Chemical Co., Ltd.)
Co., Ltd. (Catalyst) 0.1 parts by weight * 0.3 parts by weight of aqueous ammonia Fine air bubbles were fed into the mixture using an oak mixer to make it foamy (the volume should be about 2.5 to 3 times larger). desirable). A foamed urethane sheet was immersed in this mixed solution containing microbubbles. Thereafter, the weight of the impregnated foam polyurethane sheet was reduced to 150% of the weight of the foam polyurethane sheet itself. Next, this polyurethane sheet was dried at 50° C. to 70° C., and the solid content in the liquid mixture was fixed on the surface of the foam skeleton. Next, the sheet was compressed to a thickness of 5 mm while being heated with a heating plate heated to 145°C.

The microbubbles that were mixed in the Oakes mixer, contained in the mixed liquid components, and fixed on the surface of the foam skeleton expanded and collapsed during this heating and compression step. As a result, a continuous fine foam layer was formed on the surface of the sheet skeleton.

The foamed polyurethane sheets obtained in the above examples all have a fine foam layer on the surface of the foam skeleton, and are characterized by the use of commercially available foamed polyurethane sheets, which is a conventional production feature of compressed foamed polyurethane. While taking advantage of this, it had micropores that could not be obtained using conventional manufacturing methods.

〔Effect of the invention〕

The method of the present invention involves impregnating a polyurethane sheet with an open cell structure with a synthetic resin liquid mixed with a foaming agent or fine air bubbles, squeezing this impregnated synthetic resin liquid, pre-drying the polyurethane sheet, and This is an extremely simple method that involves heating the sheet and compressing it to the desired thickness.

According to the present invention, by such a simple method, a commercially available foamed polyurethane sheet having a density lower than the desired apparent density can be used to produce a foam having a desired apparent density, in particular, which cannot be obtained by conventional manufacturing methods. A porous sheet (high apparent density foam polyurethane sheet) with extremely fine pores such as a foam can optionally be obtained.

Furthermore, according to the present invention, foams with various apparent densities can be manufactured from a single sheet material, and only a single material can be prepared as the original foamed polyurethane sheet, which is extremely advantageous in terms of production. Become.

In addition, in the present invention, since the blowing agent or the fine air bubbles are heated and compressed at the same time as foaming, the pores formed by foaming become fine. Moreover, the size and number of pores in the microfoam can be adjusted from both the chemical aspects of the composition of foaming components and the foaming conditions, and the physical aspects of the compression conditions.

The compressed polyurethane foam sheet of the present invention forms another foam layer on the surface of the cytoskeleton, thereby fixing the cytoskeleton in a compressed state, so the flexibility of the original polyurethane foam itself is lost. In addition, elasticity and breathability are not impaired.

Furthermore, according to the present invention, since the foam layer is formed on the skeletal surface of the foamed polyurethane sheet of the raw fabric, compared to the conventional compressed foamed polyurethane sheet, if the apparent density is the same, the foam The pores in the skeleton are much finer. Moreover, the cells in the foam layer on the surface of the skeleton are foamed by mixing a blowing agent or air into the synthetic resin liquid, so they are much smaller than the cells in foamed polyurethane, which is produced by reacting polyol and isocyanate. The pores are fine, and since they are foamed under compression (pressurized state), the pores are even finer than when no pressure is applied.

The compressed foamed polyurethane sheet of the present invention is suitable as a filter medium, and a filter medium with a desired density can be easily obtained, and in addition, it is sufficiently strong.

It is also suitable as a cosmetic applicator, especially when used for water-based foundations, etc. Because the foam has a high apparent density, pigments do not penetrate into the applicator, making it easy to apply cosmetics and use. An easy applicator is obtained.

Furthermore, since the compressed foamed polyurethane sheet of the present invention has a foamed layer with micropores on the surface of the skeleton, it has an extremely good feel compared to conventional compressed urethane foamed sheets. It can be widely applied to fields that require good quality (for example, clothing) and other fields.

The compressed foam polyurethane sheet of the present invention can be used in a wide variety of other applications, such as cushioning materials and sound-absorbing materials.

Claims (1)

[Scope of Claims] 1. The skeleton of a polyurethane foam sheet with an open cell structure is in a compressed state, and a synthetic resin foam layer is provided on the surface of the skeleton, and the synthetic resin foam layer contains a foaming agent or air bubbles in the synthetic resin liquid. 1. A compressed foamed polyurethane sheet, which is formed by mixing and foaming, has micropores, and the synthetic resin foam layer fixes the foamed polyurethane sheet in a compressed state. 2. A step of impregnating a foamed polyurethane sheet with an open cell structure with a synthetic resin liquid mixed with a blowing agent or air bubbles, a step of squeezing the impregnated synthetic resin liquid, a step of drying the squeezed polyurethane sheet, and the above-mentioned step. The obtained polyurethane sheet is heated and compressed at a temperature at which the synthetic resin adhering to the skeleton surface foams to form a synthetic resin foam layer, and the polyurethane sheet is fixed in a compressed state by the synthetic resin foam layer. A method for producing a compressed foam polyurethane sheet.