Paper making and fiber liberation – Processes and products – Non-fiber additive
Patent
1994-08-12
1997-12-16
Lamb, Brenda A.
Paper making and fiber liberation
Processes and products
Non-fiber additive
604372, D21H 1100
Patent
active
056980787
DESCRIPTION:
BRIEF SUMMARY
DETAILED DESCRIPTION OF THE INVENTION
1. Field of the Invention
This invention relates to a wet non-woven fabric and a method for producing the same, and, more specifically, to a wet non-woven fabric having an excellent water absorption property and a method for producing the same.
2. Prior Art
Non-woven fabrics having an excellent water absorption property have already been commercialized. Most of them are dry non-woven fabrics. To improve their water absorption percentage, absorptive polymer fibers or particles are contained in the dry non-woven fabrics. In the paper making case where the-absorptive polymer fibers or particles are mixed with a wet non-woven fabric, as an absorptive polymer fiber or particle generally used has a diameter as large as 0.5 to 2.0 mm, the water absorptive polymer fiber or particle swells to approximately 1000 times its original size and has a diameter of several millimeters at mixing with water. Consequently, the water absorptive polymer fiber or particle has the disadvantage that it excludes other fibers at the time of paper-forming and falls off from the non-woven fabric when it is dried after paper-making.
Furthermore, the water absorptive polymer fiber or particle has another disadvantage that an increase in its mixing ratio with the fabric lowers the strength of the wet non-woven fabric. Therefore, to overcome this disadvantage, the absorptive polymer fiber or particle is dispersed between layers of a laminate. However, this method requires additional cost for stacking layers, thus boosting costs.
Japanese Patent Publication No. 55202/1986 discloses a method which comprises the steps of impregnating a non-woven fabric with a monomer before polymerization and then polymerizing the monomer. Since the method requires an intricate apparatus, a large amount of initial investment is necessary, also inviting an increase in costs.
DESCRIPTION OF THE INVENTION
An object of the invention is to provide a wet non-woven fabric having a uniform water absorption property.
Another object of the invention is to provide a method for producing the wet non-woven fabric of the invention with ease and at a low cost.
Other objects and advantages of the invention will become apparent in the following description.
Firstly, according to the present invention, the above-mentioned objects and advantages of the invention are attained by a wet non-woven fabric which comprises (A) a highly water absorptive polymer in an amount of 5 to 60% by weight and (B) pulp in an amount of 40 to 95% by weight, based on the total weight of the components (A) and (B).
Secondly, according to the present invention, there is provided a method for producing a wet non-woven fabric which comprises the steps of: particle while it is swollen with water; particle while it is swollen with water, together with pulp and beating them; and
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 and FIG. 2 are SEM photos of a wet non-woven fabric obtained in Example 2. FIG. 2 is an enlarged view of FIG. 1. Wrinkled portions are pulp and non-wrinkled portions are a highly water absorptive polymer.
MOST PREFERRED EMBODIMENT OF THE INVENTION
The highly water absorptive polymer used in the present invention is preferably a copolymer of a monomer having a carboxylic acid group, a monomer having a hydroxyl group that can form an ester bond upon reaction with a carboxylic acid group, and a monomer having an alkali metal salt carboxylate group. The polymer has a crosslinking structure and exhibits the water absorption ability to absorb 1200% by weight or more and less than 3000% by weight of physiological saline solution.
Examples of the monomer having a carboxylic acid group include acrylic acid (abbreviated as AA hereinafter), methacrylic acid, maleic acid and so forth. They may be used alone or in combination of two or more.
Examples of the monomer having a hydroxyl group include hydroxyethylmethacrylate (abbreviated as HEMA hereinafter), hydroxypropylmethacrylate, hydroxyethylacrylate, hydroxypropylacrylate, glyceryl monomethacrylate, glyce
REFERENCES:
patent: 2076991 (1937-04-01), Holgersson et al.
patent: 3889678 (1975-06-01), Chatterjee et al.
patent: 4270977 (1981-06-01), Hermans et al.
Agari Katsumi
Fukumoto Hiroko
Mizukami Yoshikatsu
Tanaka Yutaka
Teshima Tsutomu
Kanebo Ltd.
Lamb Brenda A.
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