JPS626816B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a highly absorbent and leak-proof film, particularly a film suitable for sanitary absorbent materials, particularly sanitary napkins and paper diapers.

Currently, sanitary napkins and paper diapers consist of an absorbent layer that absorbs excreted menstrual blood and urine, a leak-proof membrane to prevent the menstrual blood and urine from leaking to the outside, and a fibrous sheet for the part that comes into contact with the body. has been done.

The absorbent layer material is crushed pulp,
Cotton-like pulp, crepe paper, etc. are used, but the absorption capacity of these materials is due to the spaces formed in them, and is not due to their own absorption capacity. The disadvantage is that once absorbed, the aqueous liquid oozes out again. In addition, water-impermeable films such as polyethylene film and polyethylene laminated paper are used as leak-proof membranes, but although these have excellent leak-proof properties, they do not have any water solubility or water dispersibility. Because of this, it cannot be disposed of by washing with water after use. On the other hand, leak-proof membranes using water-soluble resin films such as polyvinyl alcohol resins are also used, but although these have leak-proof properties, their own absorption capacity is small.

However, the present inventors conducted extensive research to find a film that itself has absorption capacity, is leak-proof, and has the property of dissolving or dispersing in water. Such properties can be obtained by heat-treating a substantially dry film made mainly of a saponified copolymer of a vinyl ester and a water-soluble resin, or a mixture of the saponified copolymer and a water-soluble resin. It was discovered for the first time that a film having the following characteristics could be obtained, and the present invention was completed.

Napkins and paper diapers using the film of the present invention can (1) reduce the amount of the material used as the absorbent layer material, such as crushed pulp, cotton pulp, and crepe paper; Compact and not bulky when in use.
It is also convenient to carry. (2) Since the absorption capacity does not decrease even when the body is loaded, excreted menstrual blood,
Eliminates discomfort caused by urine oozing. (3) Since the film itself has water solubility or water dispersibility,
It is convenient because it can be processed by washing with water. It is possible to achieve remarkable effects such as:

In the present invention, the saponified copolymer of unsaturated dicarboxylic acid monomers (excluding unsaturated dicarboxylic acid dialkyl esters) and vinyl esters is
A copolymer of unsaturated dicarboxylic acid monomer alone or a mixture of two or more and vinyl ester is saponified with a degree of saponification of 70 mol% or more, and the amount of the monomer in the copolymer is A range of 0.2 to 50 mol% is preferred.

The water-soluble resin used in combination with the saponified copolymer is
It is preferable to select the proportion within 300 parts by weight, preferably within 150 parts by weight, based on 100 parts by weight of the saponified copolymer.

For example, the film of the present invention can be prepared by adding ethylene glycol, diethylene glycol, polyethylene glycol, glycerin, diglycerin, propylene glycol to the saponified copolymer, or a mixture of the saponified copolymer and a water-soluble resin, as necessary. , dipropylene glycol, butylene glycol, dibutylene glycol, methylpentanetriol, trimethylolpropane, and other plasticizers commonly used for polyvinyl alcohol resins are added in a proportion of 0 to 100% by weight to achieve a concentration of 10 to 100% by weight.
Thickness 10~50mm by casting method from 30% by weight aqueous solution
There are methods such as obtaining the resin as a microorganism, or melt-extruding a plasticizer or a mixture of a plasticizer and water, but a method using a casting method from an aqueous solution is preferable. Alternatively, methods such as laminating, coating, and impregnating the base material may also be used.

The heat treatment conditions for the film are such that a substantially dry film (residual water content is 1.0% by weight or less) is heat-treated at a temperature of 100 to 200 DEG C. and for a time of 1 to 360 minutes. Among the above heat treatment conditions, films treated under a combination of high temperature and long time conditions, or combinations of low temperature and short time conditions tend to have a lower absorption capacity, so please adjust the conditions accordingly. It is desirable to select and adjust.

When preparing an aqueous resin solution, borax, boric acid,
Alternatively, add acid or acidic substances to 100 parts by weight of the resin to adjust the pH of the resin aqueous solution to 2 to 6.
When added in a proportion of 0.1 to 5 parts by weight, the above heat treatment step can be shortened without impairing the properties of the film, so it is desirable to use it.

Examples of the unsaturated dicarboxylic acid monomer in the present invention include maleic acid, itaconic acid, fumaric acid,
Dicarboxylic acids such as glutaconic acid and allylmalonic acid and their anhydrides, as well as their methyl,
Examples include monoalkyl esters such as ethyl and propyl, and maleic acid monoalkyl esters are particularly preferred. Examples of the vinyl ester include vinyl formate, vinyl acetate, vinyl propionate, vinyl stearate, and vinyl acetate is preferred.

Examples of the water-soluble resin in the present invention include Japanese starch, potato starch, wheat starch,
Starches such as cornstarch, carboxymethyl starch, dialdehyde starch, and oxidized starch; seaweeds such as funori and sodium alginate; proteins such as gelatin and casein;
Celluloses such as methylcellulose, ethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, polyvinyl alcohol resins, sodium polyacrylate resins, polyethylene oxide, polyacrylamide resins,
These synthetic resins may be used alone or in combination of two or more. Among these, polyvinyl alcohol resins, polyacrylamide resins, and the like are preferred because they have high film strength and good leakproof properties.

Examples of the polyvinyl alcohol resin include polyvinyl alcohol and its derivatives (e.g., acetalized products, crosslinked products, etc.), and monomers copolymerizable with vinyl esters, such as crotonic acid, (meth)acrylic acid, etc. unsaturated monocarboxylic acids and their esters, α-olefins such as ethylene and propylene, olefin sulfonic acids such as (meth)allylsulfonic acid and ethylenesulfonic acid, sodium (meth)allylsulfonate, sodium ethylenesulfonate, etc. Amide group-containing monomers such as olefin sulfonic acid alkali salts, N-methylol acrylamide, and acrylamide alkyl sulfonates, as well as N-vinylpyrrolidone and N-vinylpyrrolidone derivatives,
Examples include saponified copolymers of vinyl ester and a small amount of vinyl ester.

Polyacrylamide resins include polyacrylamide, acrylamide copolymers (including graft polymers), saponified products of these copolymers, and unsaturated carboxylic acids such as (meth)acrylic acid as the copolymer component. and its esters, and saponified products include sodium and potassium salts of the copolymer.

In the film of the present invention, surfactants, inorganic substances such as calcium carbonate and titanium oxide, and emulsions of wax and liquid paraffin to improve the slipperiness of the film are generally added during the production of water-soluble films. It is okay to add small amounts of substances that cause

In the present invention, the film includes not only a film alone but also a film formed by laminating it with a base material, a film impregnated into a base material, a coated film, and a film having a surface treatment such as embossing.

Next, the present invention will be specifically explained with reference to Examples.

Example 1 Monomethyl maleate 5 mol% and vinyl acetate 95
Saponified copolymer consisting of mol% (saponification degree 95
mol%) 50 parts by weight and degree of saponification 88.5 mol%, degree of polymerization
From an aqueous solution with a concentration of 20% by weight of a mixture consisting of 50 parts by weight of PVA 1700, a thickness of 30
I made a μ film. This film is under tension
Heat treatment was performed at 140°C for 30 minutes.

Using this film, we created 20 layers of chillimen-like absorbent paper.
A absorbent cotton made of the above film and one layer of low-size waterproof paper was prepared, the sides of the absorbent cotton were covered with low-size waterproof paper to prevent side leakage, and the whole was wrapped with a nonwoven fabric. The width is 70mm, the length is 170mm, and the height is 6mm.

A leakage prevention test was conducted using sucked cotton having such a structure. That is, a simulated menstrual blood solution consisting of a 0.2% aqueous solution of Congo Red heated to 36°C10
cc was dripped onto the center of the surface of the absorbent cotton over a period of about 1 minute, and then left to stand for 1 minute.
When a circular weight weighing 1.0 kg was loaded, the time required for the simulated menstrual blood solution to ooze out to the back surface was measured, and it was over 60 minutes. The amount of absorbent paper used at this time was 3.0g.

Next, the dissolution and dispersion temperature of the film as is and the film that had undergone the leakage test were measured. That is, take 800 c.c. of 0°C water in a beaker 1, put a 70 mm x 170 mm film in it, let it stand at 0°C for 2 minutes, and then stir at 250 rpm with a magnetic stirrer at 0.5°C/
The temperature at which the film was dispersed or dissolved into 50 or more pieces was measured when the film was heated at a rate of 50 min, and the temperature of the film as is was 5°C, and the temperature of the film after the leakage test was 12°C.

Example 2 Concentration of saponified copolymer consisting of 5 mol% monomethyl maleate, 5 mol% monomethyl itaconate, and 90 mol% vinyl acetate (degree of saponification 90 mol%)
30μ thick by casting method from 20% by weight aqueous solution
I made a film. This film is under tension
Heat treatment was performed at 140°C for 20 minutes.

Absorbent cotton having the same structure as in Example 1 was prepared using this film, and a leakage proof test was conducted in the same manner as in Example 1. The leakage resistance test was over 60 minutes. The amount of absorbent paper used at this time was 3.0 g.

Furthermore, in the same manner as in Example 1, the melting and dispersion temperatures of the film as is and the film that had undergone the leakage test were measured; the temperature of the film as is was 6°C, and the temperature of the film that had undergone the leakage test was 13°C. Ta.

Example 3 Monomethyl maleate 5 mol% and vinyl acetate 95
Saponified copolymer consisting of mol% (saponification degree 95
mol%) 60 parts by weight and polyacrylamide resin (acrylamide 80 mol%, acrylic acid 20 mol%)
A film with a thickness of 30 μm was produced by a casting method from an aqueous solution with a concentration of 20% by weight of a mixture consisting of 40 parts by weight of a copolymer resin). This film was heat treated under tension at 140°C for 30 minutes.

Layer chilimen paper on top of 5g of this film,
Artificial urine (urea 19.4g, Nacl) is placed in the center of the chilimen paper.
8.0 g, MgSO ₄ 7H ₂ O 1.1 g, and Cacl ₂ 0.6 g dissolved in 1 part distilled water) 150 g was dropped in 1 minute, and the amount of chilimen paper required for the artificial urine to be completely absorbed was determined. As a result, 19g of chilimen paper was required.

Comparative Example 1 A leak-proof test was conducted in the same manner using a polyvinyl alcohol film (thickness: 30 μm), which is conventionally used as a leak-proof membrane, on the absorbent cotton having the structure of Example 1. It was hot. The amount of absorbent paper used at this time was 5.2 g. In addition, when the dissolution and dispersibility of the film as is and the film that had undergone the leakage test were measured in the same manner as in Example 1, the temperature of the film as is was 15°C, and the temperature of the film that had undergone the leakage test was 23°C. Ta.

Comparative Example 2 In Example 3, only chilimen paper was used and the amount of chilimen paper required for complete absorption of artificial urine was determined, and it was found that 30 g was required.

Claims (1)

[Claims] 1. Content of unsaturated dicarboxylic acid monomer is 0.2
A saponified copolymer of ~50 mol% of unsaturated dicarboxylic acid monomer (excluding unsaturated dicarboxylic acid dialkyl ester) alone or a mixture of two or more and vinyl ester, or a saponified copolymer of vinyl ester A method for producing a film having high absorbency and leak-proofing properties, which comprises heat-treating a substantially dried film containing a mixture with a water-soluble resin as a main ingredient. 2 The water-soluble resin is a polyvinyl alcohol resin,
The manufacturing method according to claim 1, which is a polyacrylamide resin.