JPS58185629A - Production of microporous membrane - Google Patents

Abstract

PURPOSE:To obtain a waterproof membrane having air and moisture permeability in a simple and inexpensive manner, by foaming a synthetic resin membrane in which a blowing agent and an electrolyte are uniformly dispersed and immersing the membrane in water to dissolve the electrolyte. CONSTITUTION:A mixture obtained by uniformly dispersing a blowing agent 3 and an electrolyte 4 in a synthetic resin is applied to the surface of a fiber substrate 1 to form a synthetic resin membrane 2, which then is foamed. In this foaming, the electrolyte 4 readily serves as foaming nuclei, so that open cells are formed about the electrolyte. When this is immersed in water to dissolve the electrolyte 4, the pores occupied by the electrolyte and the micropores of the blowing agent 3 are formed and form continuous pores, so that a membrane having micropores necessary to render the membrane air-permeable can be made. Formation of the synthetic resin membrane can be carried out by coating, melt extrusion or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a synthetic resin film having 4:i narrow pores. More specifically, the present invention relates to a method for producing a waterproof film having air permeability and moisture permeability.

Conventionally, methods for producing films with micropores include creating an unfired film using tetrafluoroethylene resin and rapidly stretching it to create a fibrillated porous body. The coating is formed by coagulating the resin while removing the solvent in an aqueous coagulation bath containing a polar organic bath such as dimethylformamide. A method of forming fine pores in a synthetic resin, a method of forming a film containing fine air bubbles by screen coating a foamed aqueous resin, and a method of forming a film containing fine air bubbles by mixing a foaming agent into a synthetic resin and foaming it. There are methods of forming a film containing

However, in these conventional methods, the resin is expensive, special manufacturing equipment is required, and wet coagulation methods require bath agent-based urethane resins. It contains many elements that make workability unstable, and in order to reproducibly form a film with micropores, extremely complicated operations and strict processes and controls are required. There are problems with pollution control, such as the huge expense required for waste liquid treatment.On the other hand,
If this method simply uses a foaming agent, it is difficult to distribute the micropores uniformly on the surface and inside of the film, and it is difficult to obtain sufficient air permeability. The development of a manufacturing method was being developed.

The non-explosion ψ() was devised to solve these conventional problems and provides a method for producing an air-permeable, moisture-permeable, and waterproof film that can be produced extremely easily and at low cost.

In other words, unexploded ψ] is made into a fine powder in a synthetic resin and then formed into a film using a mixture of a chemical (foaming agent) that decomposes and generates gas upon heating (foaming agent) and an electrolyte uniformly dispersed therein, and then foamed. This method is characterized in that fine pores are created in the synthetic resin film by immersing it in water and exposing it to an electrolytic bath.

In general, if a synthetic m resin is simply foamed using a blowing agent, there will be many closed cells, and the air bubbles will be concentrated inside the resin film, resulting in insufficient foaming on the surface and poor air permeability. It was very hard to get wet.

In the present invention, by using a foaming agent and an electrolyte in combination, it is possible to form fine pores uniformly on the surface and inside of the synthetic resin by bathing out the "ilt solute in foaming water", thereby making it possible to create air permeability. Our goal is to easily form a film that is permeable and waterproof.

This will be explained in detail below using the drawings. In Fig. 1, (A) indicates a fiber base made of fabric, 4Ii8v1:J, etc., and ■ indicates a synthetic resin film formed on the base fabric and soil.■ indicates a constant sound in the synthetic film. , indicates a fine blowing agent that is uniformly dispersed, and ■ indicates a fine inorganic electrolyte that is uniformly dispersed with a constant bar as in ■.Next, the composition of (a) is heated to decompose the blowing agent ■. and foam.At this time, electrolyte ■
tends to become the nucleus of foaming, and electrolyte (4)? Create an open cell at the center.

(b) shows the state after foaming. (4)' shows the state of the foaming agent after foaming. After that, it is immersed in water and when the electrolyte ■ is extracted, the pores where the electrolyte ■ was present coexist with the fine pores of the foaming agent ■, creating continuous pores and improving air permeability. It is possible to create a film ``■'' having 2 micropores. Here, it is a commonly known fact that the diameter of water droplets during drizzle is about 100 microns, and that during a thunderstorm is 30 microns in diameter.
It is said to be about 0.00 microns. On the other hand, that of air and water vapor is said to be about 4 microns. Therefore, the blowing agent used in the present invention and 1t'MIJ! By setting the particle size of the powder to about 0.1 to 15 microns, water droplets can be blocked, but air and water vapor can be recirculated through the perforated membrane. But better waterproofing? If you want to obtain it, it is better to powder it to less than 1 oξ chron V (imitation wholesaler).

The synthetic resin for film formation described in the present invention may be any resin that can form a film, such as urethane resin, acrylic resin, polyamide thread resin, polyester resin, etc., which can be used in normal yaw processing and lamination processing. As the film forming method, any method such as a coating method or a bath melt extrusion method may be used.

The blowing agents mentioned in the present invention include ammonium hydrogen carbonate,
Various fluent substances such as sodium bicarbonate, ammonium carbonate, hydroxymethylthiourea, and ammonium alum, azo compounds such as diazoaminobenzene, azobisnitrile, azobisisobutylnitrile, dinitrone pentamethylene/tetramine, etc. A commonly used blowing agent such as a 1q-nitroso compound may be used.

The '#tm qualities mentioned in the present invention include sodium chloride,
It is possible to use any metal that is commonly understood as water, such as calcium chloride, magnesium chloride, and various alums.

Further, as the base fabric of the woven fabric, knitted fabric, etc. described in FIG. 1 of the present invention, any fiber such as polyamide fiber, polyester fiber, polyester/cotton blend fiber, cotton, acrylic fiber, etc. can be used.

In addition, in order to use it as a waterproof cloth, the effect is further improved if the fiber base is previously subjected to 7) water repellent treatment using yarn or a silicone water repellent.

Examples are shown below.

<Example-1> (1) After squeezing a nylon plain woven fabric (fabric weight 659 / rri'') with the treatment solution (a) below at a squeezing rate of 80%, pre-drying at 100°C for 2 minutes and then 16 more
Water repellency treatment was performed by keying for 2 minutes at a temperature of 0°C.

(a) Treatment liquid DI COU A, RI) F -70...-Tagawa... = 1% weight analysis (7 elemental water repellent manufactured by Inu Nippon Ink Co., Ltd.) (2) Next, the T obtained by ZllK This nylon plain woven fabric K'F Urethane thread coating agent containing a foaming agent and an electrolyte consisting of the following formulation (b) = 17000CP
SIC and wet 150. Coat with a p/var coater and heat for 2 minutes at 85°C.

(J treatment liquid OCRISVON 2016EL 100i
Part ii (urethane film for coating process manufactured by Inu Nippon Ink Co., Ltd.)
No. 5 5 parts by weight (plane smoothing agent made by the same company) OCRISVOr NX 2
Mfir part (isocyanate-based crosslinking agent manufactured by the company) o CRISVON Accel JAM
1 weight 1 part (Creating accelerator made by the same company) 0 Ammonium carbonate powder 15]i
Part 0 Calcium chloride powder 15
] iB part 0 methyl ethyl ketone
30 weight 1 part (Ammonium carbonate and calcium chloride powders are ground in a ball mill in advance to obtain an average particle size of 201~
1 piece with a range of 15 microns. ) After heating in this manner, a urethane film having micropores due to foaming was obtained.

(3) Furthermore, one coated cloth obtained in (2) was immersed in water at 40°C for 60 minutes to remove calcium chloride, and dried at 90°C for 1 minute in the open, resulting in closed cell foam. The previously fine pores have become continuous, improving breathability and
The film has good moisture permeability and waterproof properties. The measured values regarding the breathability and waterproofness of the fabric thus obtained are as follows.

Water pressure resistance: JIS L-1092 (1977) 5.1
1. A (al hydrostatic pressure method moisture permeability: JIS Z-020
8 (force 7 method) Air permeability: JIS p-all ゛Example-2〉 (1) The following treatment solution (A) was applied to a polyester/cotton (55/35) blended broadcloth (fabric weight 100 g/m').
The pre-water repellent treatment was carried out as in Example-1.

(B) Processing liquid D J, (': 0 [I A, Ding (Ding) +1' -70... . . .
-1% 1 No. 1111 parts water
...Song...99% 〃(2) Furthermore, in order to give smoothness to this treated cloth, smoothness was imparted using a calender roll with 30 kg of pressure.1
child.

(3) Next, a urethane-based coating agent containing a foaming agent and an electrolyte made from the formulation (b) below a1 was applied wet to the treated fabric obtained in (2) using a 1509/m' burgeter. Then, the film was further heated at 120° C. for 2 minutes to obtain a film having micropores due to foaming.

10) Processing liquid 0 (4RISVON 2016EL, 1
00] ii part OfJRIsVON ADDITIVE
N05 5th army store QC) (ISVQN NX
2/1
0 CRISVON Accel-HM
1 ttO ammonium alum powder 15 〃0 Sodium chloride powder
15/10 methyl ethyl ketone
30 (The particle size of sodium chloride and ammonia alum is 01 to 1 as in Example-1.
The range is 5 microns/T. ) The viscosity of these mixed liquids is 21.0OOCPS (25°C
) and one.

(4) Further, in step 131, the coated cloth obtained by the method was immersed in water at 23°C for 50 minutes to be salted) 1
When the foam was extracted and dried in an oven at 90° C. for 1 minute, the closed cells became continuous as in Example 1, and a processed fabric having air permeability, moisture permeability, and waterproofness was obtained.

The measured values regarding the breathability and waterproofness of the fabric obtained by this nK are as follows.

Water pressure resistance: 1s o aIllIH2o/crd4f
W degree: 5.00097m', 24 hrs ventilation =
06cc/sec/Cr!

[Brief explanation of the drawing]

The drawings show embodiments of the present invention, and FIGS. (shi)...Fiber base (2)...synthetic resin film (
2...Blowing agent q)...Inorganic electrolyte, W Applicant: Toppan Printing Co., Ltd. Figure 1

Claims (1)

[Claims] (1) A foaming agent and an electrolyte are uniformly dispersed in a synthetic resin, mixed together to form a 91J film, placed in a cutting place, and then immersed in water to dissolve the electrolyte and imitate it into a synthetic resin film. A method for producing a porous layer characterized by creating fine pores.