JPS6065184A - Production of sheetlike composite material - Google Patents

Abstract

PURPOSE:To prevent an emulsion material from concentrating on the surface and obtain a sheetlike composite material having uniformly applied emulsion material, by applying a water absorbing material to the sheetlike material when applying the emulsion consisting essentially of water as a main dispersion medium to the sheetlike material, and drying the applied emulsion. CONSTITUTION:An emulsion consisting of a viscoelastic material, e.g. polyurethane, natural rubber or polyacrylic acid copolymer, in water as a main dispersion medium is applied to a sheetlike material to give a sheetlike composite material. In the process, a highly water absorbing material, e.g. a polymer obtained by grafting acrylic acid onto starch or high-molecular weight polyacrylamide, having >=40 times, preferably >=50 times water absorption ratio is applied to the sheetlike material and dried. If the sheet requires the water absorption properties, the sheet is preferably dried at a low temperature (100 deg.C or below). On the other hand, if the sheet requires no water absorption properties at all, the sheet is preferably dried at 150 deg.C or above. The highly water absorbing material is preferably applied by blending with the emulsion.

Description

TECHNICAL FIELD The present invention relates to a method for producing a sheet-like composite by applying an emulsion material to a sheet.

(Conventional technology) In recent years, various resins have been added to sheet materials.

Its use as a composite material has become very widespread.A typical example is so-called artificial leather.The resin applied in these cases is often a viscoelastic substance such as polyurethane.These resins may be applied in a solution or in the form of an emulsion.In the case of a solution.

A step to remove the solvent is inevitably required. but.

Polymer solvents are often highly flammable or highly toxic substances. Therefore, fire.

In order to prevent toxicity hazards, great care must be taken during solvent recovery, resulting in very high costs. Due to these various problems, various studies have been made to shift from a solution system to a one-mulsion system, but in the case of an emulsion system.

A major drawback was that the emulsion substance was difficult to apply uniformly. That is, when a sheet material was impregnated with an emulsion and dried, a phenomenon was observed in which particles dispersed in the solution moved into the medium and were concentrated on the surface of the sheet.

If the emulsion material cannot be applied uniformly.

Not only does it have a significant adverse effect on the physical properties (for example, strength and elongation, flexibility, etc.), texture, quality, etc. of the sheet, but it may also seriously impede the processability of the sheet. For example, when making suede-like artificial leather by brushing sheets, if a lot of emulsion substances adhere to the surface,
The length of the tips may become uneven or they may become tangled, making it impossible to obtain a high-quality nap product. In order to uniformly apply the emulsion substance, a substance called a so-called migration inhibitor is used. However, the current situation is that this has little effect and is not a fundamental solution. A method of rapidly freezing the emulsion-applied sheet and then drying it is also known, but freeze-drying is extremely expensive, which is a big handicap for industrialization.

On the other hand, a method in which a sheet material impregnated with an emulsion is directly coagulated in a liquid bath is not generally employed. The reason for this is that a large amount of emulsion falls off during coagulation, making it impossible to avoid contamination of the coagulation bath.

In other words, in the case of an emulsion type, it is extremely difficult to industrially apply an emulsion substance uniformly to a sheet.

(Objective of the present invention) In order to solve this problem, the present inventors have arrived at the present invention as a result of intensive studies.

In other words, one object of the present invention is to overcome the various drawbacks seen in the prior art by uniformly and easily applying an emulsion substance to a sheet.

(Configuration of the present invention) In order to achieve the above object, the present invention has the following configuration. That is, in a method for producing a sheet-like composite by applying an esterion having water as the main dispersion medium to a sheet-like object, the method is characterized in that after applying a highly water-absorbing substance to the sheet-like object, drying is performed. A method for producing a sheet-like composite.

This will be explained in more detail below.

In the present invention, the sheet material to which the emulsion is applied includes nylon, polyester, acrylic, cotton,
Examples include fabrics made of glass, metal, etc., and combinations thereof, and composites made of these and resins. but.

In particular, when a product with high strength and flexibility is desired, it is preferable to use a sheet mainly composed of ultrafine fibers. The sheet density should also be appropriately determined depending on the application and is not particularly limited. In the present invention, the main dispersion medium of the emulsion is water. This is because water as a dispersion medium has many advantages such as ease of handling and safety.

As a matter of course, a dispersion medium other than water may also be included.

In the emulsion of the present invention, one dispersion medium is liquid, and the object to be dispersed is liquid, solid, or a combination thereof.

Whatever is dispersed is not particularly limited. The effects of the present invention can be achieved in any case, such as solid or liquid, organic or inorganic, low molecular weight, or high molecular weight. Particularly widely applicable.

Viscoelastic substances, such as polyurethane, natural rubber.

5- Polyvinyl chloride (copolymer), polyamide (copolymer)
, polyamic acid, ethylene-vinyl acetate copolymer, polyacrylic acid copolymer, polyacrylic acid ester, NBR
etc., or compositions containing them.

Also, various stabilizers such as weathering agents are included in the emulsion.

Also, there is no problem even if a migration preventive agent or the like is contained.

The concentration of the emulsion varies greatly depending on the degree of porosity of the sheet, the viscosity of the emulsion, etc., and cannot be generalized.

Further, the size of the emulsion particles varies greatly depending on the emulsion type, etc., and cannot be generalized, but larger types are preferable. In the case of an aqueous emulsion of a high-molecular viscoelastic substance such as polyurethane, a particle size of 0.08 μm or more is desirable from the viewpoint of uniform application of the emulsion.

Next, the emulsion is applied to the sheet by conventional methods such as impregnation, spraying, coating, etc. In this case, in order to prevent uneven application to the sheet, it is desirable to select the appropriate amount in consideration of the type of sheet (thickness, density, porosity, etc.), viscosity of the emulsion, etc.

Impregnation using a mangle is very effective in applying an emulsion of polyurethane, various rubbers, etc. to materials made of relatively flexible and high-density IN-like materials, such as the base fabric of artificial leather. Furthermore, (1) the amount of the emulsion substance to be applied may be any value depending on the purpose.

For example, when manufacturing suede type synthetic leather, if the base fabric is a nonwoven fabric, it is desirable to use 5 to 150 parts based on the nonwoven fabric, and when the base fabric is a knitted fabric, it is desirable to use 1 to 150 parts based on the knitted fabric.

The highly water-absorbing substance in the present invention refers to a substance that is mainly composed of a polymer and has a water absorption rate of at least 40 times or more. A particularly preferable water absorption rate is 50 times or more. Here, the water absorption rate is determined by placing the polymer in a tea bag (made of non-woven fabric), allowing it to absorb enough water (at room temperature, for 1 hour), and then draining the water.

The weight was measured and the weight change before and after water absorption was calculated.

Examples of such highly water-absorbing substances include starch starch and acrylic acid graft polymerized, acrylic acid polymerized into polymers, high molecular weight polyacrylamide, and various substances grafted with these materials. can give.

The amount of such a substance to be applied is determined depending on the application method and the intended use. One of the major features of the present invention is that a large effect can be achieved by adding an extremely small amount of superabsorbent substance to the sheet.

The present invention is characterized in that the sheet-like material is dried after applying the superabsorbent substance to the sheet-like material. That is, the highly water-absorbent substance may be applied to the sheet material either before or after the emulsion is applied to the sheet material, or at the same time as the emulsion is applied. Furthermore, a combination of these may be used. In particular, it is preferable to blend the superabsorbent substance and the emulsion and apply them simultaneously to the sheet material from the viewpoint of uniform application and process simplification.

In short, in order to obtain the effects of the present invention, it is sufficient that the superabsorbent substance is applied to the sheet before drying.

There are various specific methods for drying, but one typical method is heat treatment. The heat treatment includes hot air heating, infrared heating, high frequency heating, steam treatment, etc., or a combination thereof.

Heating time and temperature vary greatly depending on sheet type, ■mulsion concentration, and viscosity. When applying an emulsion of various viscoelastic substances to a base fabric of synthetic leather, etc., it is preferable to apply the emulsion at a temperature higher than the atmospheric temperature at which the application is performed by at least 10°C, particularly preferably at least 20"C. Heating. The time varies greatly depending on the heating method, but if the emulsion has a high viscosity or concentration, even a very short time is effective.

Maximum heating temperature (ambient temperature in case of hot air method, etc.) is 20
Even a high temperature of 0°C is sufficient.

Note that if the sheet to which the emulsion is applied requires water absorbency, the drying is preferably carried out at a lower temperature. It is preferable to carry out the process at a temperature of 100°C or lower if possible.

On the other hand, if water absorption is not required at all, it is preferable to treat at a high temperature of 150°C.
It should be carried out at temperatures above ℃. Also as appropriate.

Needless to say, a treatment to wash out the highly water-absorbing substance may be performed.

Note that, as a matter of course, in order to sufficiently fix the emulsion, it is also an effective method to appropriately apply heat setting or the like.

(Effects of the Present Invention) By adopting such a configuration, the present invention exhibits the following extremely significant effects.

(1) The emulsion can be easily and uniformly applied to a sheet-like material, and the effect is achieved even if the amount of the superabsorbent substance added is extremely small, so there are no problems associated with the addition of the superabsorbent substance.

(2) Therefore, the peeling strength of the sheet is greatly improved.

(3) Even if the sheet is thick, the adhesion rate of the emulsion dispersion in the direction of the sheet thickness can be kept constant. For this reason,
Material uniformity can be achieved. Furthermore, even when used in slices, the physical properties of each slice remain constant.

(4) Even when using a particularly low-concentration emulsion, it can be easily applied to a sheet-like material, probably because it increases in viscosity by adding a highly water-absorbent substance.

(5) Even if the sheet has a high porosity, the emulsion can be uniformly applied to the sheet. As a result, the range of uses for the sheet has expanded.

(6) Since even low concentration emulsions can be applied to the sheet, even emulsions with poor stability can now be used.

(Even if an emulsion is unstable at a high concentration, it becomes stable if the concentration is lowered.) (7) If the emulsion is dried at a low temperature, water absorbency can be imparted to the sheet.

(8) The texture of the sheet can be made flexible.

(9) In particular, when the fibers constituting the sheet are ultrafine fibers and the emulsion is an elastomer polymer, a sheet-like product with a soft texture and high strength can be obtained.

Although the details of why the present invention is so effective are unknown, it is thought to be as follows.

In other words, the main dispersion medium, water, was adsorbed by the highly water-absorbing substance and the emulsion was destroyed, making migration impossible, and the viscosity increased, making migration even more impossible. It will be done.

One of the major fields of application of the present invention is the field of suede-like artificial leather. Conventionally, in the production of suede-like artificial leather, a method has been adopted in which a 100% viscoelastic substance is applied as a solution. it is.

This is because when the emulsion was conventionally applied using the film force method, migration occurred and it adhered only to the sheet surface, and no napping occurred at all. However, this problem could also be solved by the invention of this method.

Hereinafter, the effects of the invention will be described in more detail with reference to Examples.

Measurements of Examples of the present invention were carried out under the following conditions.

(1) Strength: Tensilon type tensile tester Sumpur medium 2C
A sample length of 10 cm was pulled at a speed of 1001/min to determine the strength and elongation at the time of cutting.

(2) Bending resistance: L1079 Method A (45″ cantilever method) 3) Cut out the peel-resistant crab sheet into a rectangle measuring 20c+e in the longitudinal direction and 2G- in the transverse direction.After that, from one end of the sheet, cut the sheet thickness. Make a 50-cut in approximately the center of the slice, and clamp both sliced ends to a clamp length of 5.
cm) It was pulled at a speed of 5 cm/min using a Tensilon type tensile tester, and the cutting strength at that time was defined as the peeling strength.

Example 1 Raw polyester cotton of 1.5 denier and 38 rrel was passed through a card and a cross wrapper to form a web, which was then needle bunched to form a felt.

The weight of the felt is 5200/-, and the thickness is 2.9
It was mm.

Next, emulsion polyurethane (with water as the main dispersion medium)
An emulsion polyurethane in which 0.005% of a super absorbent substance (Sanyo Kasei Co., Ltd.'s Sunwet 13-1M-300: water absorption rate of 60 times) was added to 0.005% of the active ingredient of polyurethane (10% by weight) was applied to the shrink felt. did.

The amount applied was about three times the weight of the felt. Further, the sheet was dried with hot air at 150°C for 10 minutes.

Water was removed and polyurethane was heat set.

The amount of polyurethane applied was calculated to be 20.2 parts based on the weight of the raw polyester cotton.

When the peel strength of the sheet was measured, it was found to be extremely high at 3.2 km ZC-. Further, when observed under a microscope, polyurethane was uniformly applied to the sheet.

Comparative Example 1 The felt of Example 1 was coated with the same emulsion polyurethane as in Example 1 but containing no superabsorbent substance, and further treated in the same manner as in Example 1.

The amount of polyurethane applied was calculated to be 21.3 parts based on the weight of the raw polyester cotton.

14- When the peel strength of the sheet was measured, it was 1.15 with 9/CI
The intensity was very low.

Further, when observed under a microscope, it was found that the polyurethane was only attached to the surface of the sheet, and significant migration had occurred.

Example 2 The island component is nylon-6, the sea component is polystyrene, the weight ratio of the island to the sea is 60:4, the number of islands is 36, and the fineness is 3.5.
Using denier polymer interlayer fibers, a card and a cross wrapper were used to create a web. It was then needle bunched to make felt. The apparent density of the felt was 0.18 alad. After this, the felt
It was treated in hot water at 0°C to shrink. The actual shrinkage rate is 18%
Met. The felt weight of excellent shrinkage is 708 G/t.
It was n2.

Next, an emulsion polyurethane containing water as the main dispersion medium as in Example 1 (the active ingredient of the polyurethane was 10% by weight) was prepared.
) with a super absorbent material (manufactured by Sanyo Kasei Co., Ltd., Sunwet I)
An emulsion polyurethane to which 0.005% of M-300) was added was applied to the shrinkable felt.

The amount applied was about three times the weight of the felt.

Next, the sheet to which the emulsion polyurethane was applied was dried with hot air at 150° C. for 10 minutes to remove moisture and heat set the polyurethane.

The amount of polyurethane attached to the island fibers was calculated to be 48 parts.

Next, the sea component was removed using Triclean.

The calculated removal rate of sea components was 98.8%.

Further, the sheet was sliced, and the unsliced surface was puffed to obtain a suede-like sheet with a basis weight of 1890/yn'.

The nap on the sheet surface was dense and of good quality. The thickness of this sheet is 0.59mm and the strength is 8.6kg/c in the longitudinal direction.
m, horizontal direction 11,4 kg/cm, bending strength is longitudinal direction 6
It was 7 mm in width and 65 a, high in strength and highly flexible.

Comparative Example 2 The emulsion polyurethane of Example 2 (the active ingredient of the polyurethane was 10% by weight) was applied to the shrink felt of Example 2, and the same as in Example 2 was dried with hot air. The amount of polyurethane attached to the island fibers was calculated to be 52 parts. Furthermore, as in Example 2, the sea component was removed (removal rate, calculationally,
99%).

Slice and puff the non-sliced side to a thickness of 0°60
11wn suede style sheet. However, the naps on the surface of the sheet were unkempt, had long and short edges, and were of very low quality. The basis weight of the sheet is 172a/-, and it does not struggle even though a large amount of polyurethane is added.

It had a low basis weight. The strength of the sheet is 5°2 kg/longitudinal direction.
am, lateral direction 8.5kg/a1. ! : It has a low strength r, and the bending resistance is 65 mm in the longitudinal direction and 64 nvn in the transverse direction, which is practically the same as Example 2, and it was found that it did not become flexible despite having low strength.

Patent applicant Higashi Shikikai Co., Ltd. 17-1

Claims (2)

[Claims] (1) In a method of producing a sheet-like composite by applying an emulsion containing water as the main dispersion medium to a sheet-like material,
After applying a super absorbent substance to a sheet material. A method for producing a sheet-like composite, characterized by drying. (2) The method for producing a sheet-like composite according to claim (1), wherein the blend of the super absorbent substance and the emulsion is applied to the sheet-like material and then dried.