JPH0524279B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to a polyester fiber paper containing short polyester fibers, and more particularly to a polyester fiber paper that has excellent paper strength and hiding properties, and has an extremely soft texture. (Conventional technology) Recently, as lifestyle changes and technological innovations become more sophisticated, the performance required of paper has increased, and vinylon, nylon,
Synthetic fibers such as polyacrylonitrile and polyester are increasingly being used as raw materials for paper. Paper made from synthetic fibers generally has excellent moisture resistance, weather resistance, electrical insulation properties, etc., and is therefore expected to develop in special fields in the future. Among these synthetic fibers, vinylon fiber and polyacrylonitrile fiber have traditionally been used in large quantities;
Recently, various attempts have been made to develop paper using polyester fibers having the most excellent performance due to increasingly sophisticated performance requirements. However, conventional polyester fiber papers using short polyester fibers have a high basis weight, are thick, have a hard texture, and have the drawbacks of high paper fees and high costs. Therefore, if the basis weight is lowered and the thickness is reduced, the texture will be softer and the cost will be lowered, but the paper strength will be lowered and the hiding power will be lowered, making it suitable for clothing, especially surgical gowns, medical materials, sanitary materials, etc. The problem arises that it is not suitable. On the other hand, Japanese Patent Application Laid-open No. 110545/1983 proposes an attempt to improve the bulk and texture of paper by using polyester fibers as threads with irregular cross-sections such as T-shapes, Y-shapes, and star-shapes. However, even if such a yarn with an irregular cross section is used, the various problems mentioned above cannot be solved. Furthermore, Japanese Patent Application Laid-Open No. 57-29700 proposes an attempt to soften the texture of paper by using polyester fibers that spontaneously expand irreversibly in water at 90°C. If only spontaneously elongated polyester fibers are used, a slight improvement in feel is observed, but the other problems mentioned above cannot be solved. (Problems to be Solved by the Invention) The present invention solves the various problems described above, and even if the thickness of the paper is reduced, the paper has high strength and excellent hiding properties.
Moreover, it is an object of the present invention to provide a polyester fiber paper which has an extremely soft texture and is suitable for medical use, surgical gowns, medical materials, sanitary materials, and the like. (Means for solving the problems) The present invention has a single yarn fineness of 0.5 to 15 deniers, a single yarn length of 3 to 25 mm, a hollow portion continuous in the fiber axis direction, and a temperature of 90°C. Polyester short fibers that spontaneously elongate irreversibly in water are used in an amount of 5% by weight based on the total fiber components constituting the polyester fiber paper.
A polyester fiber paper containing the above,
When the weight of the paper is 50g/ ^m2 , the paper strength is 5.8
Kg/5cm or more, concealment (opacity) 65% or more,
It is a polyester fiber paper characterized by a bending resistance of 7.5 cm or less. Polyethylene terephthalate is suitable as the polyester used in the present invention, but some of its acid components and/or diol components are dicarboxylic acids such as isophthalic acid, sebacic acid, and 5-sodium sulfoisophthalate, diethylene glycol,
Copolymerized polyesters substituted with diols such as 1,4-butanediol and polyethylene glycol may also be used. Moreover, polybutylene terephthalate, polypropylene terephthalate, etc. are also suitably used. These polyesters have matting agents,
It goes without saying that a fluorescent brightener, an antistatic agent, a flame retardant, etc. may be added. The polyester fibers contained in the polyester fiber paper of the present invention have a single yarn fineness of 0.5 to 15 deniers, preferably 2 to 8 deniers, and a single yarn length of 3 to 25 deniers.
mm, preferably 5 to 15 mm. When the single yarn fineness exceeds 15 denier, the paper strength decreases and the texture becomes hard. Hollow spontaneously elongated fibers with a single filament fineness of less than 0.5 denier are difficult to produce. Furthermore, if the length of the single yarn is shorter than 3 mm, the paper strength will be insufficient, and if it exceeds 25 mm, the dispersibility in water will be poor and quality unevenness will occur. Further, the short polyester fibers contained in the polyester fiber paper of the present invention must have hollow portions that are continuous in the fiber axis direction, and it is particularly desirable that the hollow portion is 5% or more. The hollow rate is
If it exceeds 45%, the hollow portion tends to be easily deformed. Here, the term "hollowness ratio" refers to the ratio (%) of the total area of hollow parts in a fiber cross section to the area surrounded by the outer periphery of the cross section. If this hollow part does not exist, concealment performance will not be improved. The cross-sectional shape of the polyester short fibers used in the present invention can be any shape such as round, triangular, square, etc. Furthermore, the number of hollow parts is not limited to one, but may be plural. Especially if it is made porous and hollow,
The texture is softer and the concealability is further improved. FIGS. 1 to 5 show examples of cross-sectional shapes of polyester short fibers used in the present invention, and E indicates a hollow portion. In addition, the polyester short fibers contained in the polyester fiber paper of the present invention are required to irreversibly elongate spontaneously in water at 90°C. If ordinary fibers without spontaneous extensibility are used, a sufficiently soft texture cannot be obtained. Polyester fibers that irreversibly stretch spontaneously in water at 90°C can be obtained as fibers with low oriented crystallinity by stretching in a relatively low-temperature water bath and then shrinking in a water bath at 85°C to 95°C. . In the present invention, by making the hollow polyester fibers spontaneously extensible, the feel is significantly improved compared to those that are simply hollow fibers, and the hiding property is improved compared to those that are simply made spontaneously extensible. When the opacity (opacity) is greatly improved, the following effects are realized. The polyester fiber paper of the present invention may be made from such short polyester fibers alone, and may include other synthetic fibers such as vinylon and nylon, recycled fibers such as rayon, inorganic fibers such as glass and asbestos, and natural fibers such as wood pulp. A mixture of such materials may also be used. In particular, paper mixed with rayon pulp has a remarkable effect of improving paper strength. In particular, when polyester short fibers made of polyester copolymerized with 5-sodium sulfoisophthalic acid are used, the binding strength with pulp and rayon is increased, and the paper strength is further increased. Moreover, a small amount of fibrous binder may be added as a binder component. When carrying out mixed papermaking in this manner, it is important to contain the above-mentioned short polyester fibers in an amount of 5% by weight or more based on the total fiber components in order to achieve the object of the present invention. The polyester fiber paper of the present invention is usually produced by wet papermaking, but it may also be produced by dry papermaking. Since the polyester fiber paper of the present invention contains 5% by weight or more of polyester staple fibers having a specific single yarn fineness and single yarn length,
Even if it is a thin paper with a basis weight of 50g/ ^m2 , it weighs 5.8Kg/
It has sufficient paper strength of 5 cm or more. Also,
Since hollow fibers are used, light is diffusely reflected and exhibits excellent hiding properties. Furthermore, since spontaneous elongation is used, polyester fiber paper is elongated by heat treatment such as drying after paper making, and this, combined with the low degree of oriented crystallinity, gives it a soft texture. Has characteristics. Due to the mutual effect of having the above-mentioned hollowness and having spontaneous extensibility, the basis weight is 50g/m ²
Even with such thin paper, it exhibits extremely good hiding properties with a hiding property of 65% or more and a bending resistance of 7.5 cm or less, and a soft texture. (Examples) Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples. Incidentally, the spontaneous elongation rate of the polyester short fibers and the paper strength, hiding property, and bending resistance (softness) of the polyester fiber paper were measured by the following method. (1) Spontaneous elongation rate: Treat the sample in water at 90°C for 20 minutes, and calculate the length after treatment using the following formula. l−l ₀ /l ₀ ×100 (%) Here, l ₀ represents the length of the sample before treatment, and l represents the length of the sample after treatment. (2) Paper pinching force: using a constant speed extension type tensile tester JIS-P
Measured according to method -8113. (3) Hiding ability (opacity): Measured according to the method of JIS-P-8138. (4) Bending resistance Measured according to the cantilever method. Examples 1 to 10, Comparative Examples 1 to 3 A polyethylene terephthalate chip with an intrinsic viscosity of 0.65 was melted at 300°C, and a hollow fiber nozzle was heated at 1200°C.
Discharged at 285°C through a spinneret with holes,
It was picked up at a speed of 1000m/min. At this time, the dimensions and discharge amount of the nozzle were varied to obtain undrawn yarns with the cross-sectional shapes shown in Fig. 1 having different hollowness ratios and finenesses.
After stretching 2.8 times, stretch it in water at 95℃ for 2 seconds.
It was shrunk by 40% and cut into various lengths. The obtained short fibers are dispersed in water so that the fiber concentration is 0.5%, and at the same time pulp and polyvinyl alcohol fibrous binder (fineness 1 denier, length 3 mm, softening temperature in water approximately 70°C, product name Fibril Bond No. .
343, manufactured by Kuraray Co., Ltd.) was added at the following mixing ratio. Blend ratio Polyester short fibers: 50% Pulp: 30% Polyvinyl alcohol fibrous binder: 20% This dispersion was sent to a cylinder paper machine, and paper with a basis weight of 50 g/m ² was obtained by a conventional method. The spontaneous elongation rate, specific gravity, paper strength, hiding property (opacity), bending resistance, and paper-making properties of the obtained polyester short fibers in the paper-making process were as shown in Table 1.

【table】

[Table] As is clear from Table 1, the polyester fiber papers of the present invention (Examples 1 to 10) have high paper strength, excellent hiding properties, low bending resistance, soft texture, and paper-making properties. It was also good. On the other hand, when the single yarn fineness exceeded 15 denier (Comparative Example 1), the paper strength was low, the bending resistance was high, and the texture was hard. Furthermore, if the length of the single yarn is less than 3 mm (Comparative Example 2), the paper strength will decrease, and if it exceeds 25 mm (Comparative Example 3), the dispersibility in water will be poor, the paper-making properties will be poor, and the paper thickness will decrease. There were many spots and it was not possible to obtain a satisfactory paper. In addition, hollow fibers with a single filament fineness of less than 0.5 denier,
It was difficult to spin. In addition, the hollow ratio is 5
% or higher, there was a tendency for the improvement in hiding properties and texture to become particularly remarkable. Comparative Example 4 In Example 2, short fibers with a round cross section were obtained by spinning using an ordinary circular nozzle, and paper was made under the same conditions as in Example 2. The strength of the paper obtained was 7.5Kg/5cm, the opacity was low at 60%, and the hiding power was poor, and the stiffness was also low.
The texture was hard at 8.5cm. Comparative Example 5 In Example 2, stretching was carried out at 2.8 degrees in hot water at 70 degrees.
After that, the paper was subjected to free shrinkage heat treatment in an atmosphere of 140°C, and other conditions were the same as in Example 2 to make paper. The short fibers obtained did not elongate spontaneously and shrank 1.3% in water at 90 degrees. Also, the strength of the obtained paper is 5.0
Kg/5cm, opacity was 65%, poor hiding power, bending resistance was 10.2cm, and the texture was hard. Examples 11 to 14 In Example 2, the cross-sectional shape is as shown in Figures 2 to 5.
Using porous hollow polyester fiber as shown in the figure,
Other conditions were the same as in Example 2 to make paper. The spontaneous elongation rate, paper strength, hiding property (opacity), bending resistance, and paper-making properties in the paper-making process of the obtained polyester short fibers were as shown in Table 2.

[Table] As is clear from Table 2, when porous hollow polyester fibers were used (Examples 11 to 14),
The opacity was higher than that in the case of using a polyester fiber having one hollow part (Example 2), the hiding property was excellent, and the texture was also soft. Examples 15 to 17, Comparative Examples 6 and 7 Paper was made in the same manner as in Example 2, except that the blending ratios of short polyester fibers, pulp, and polyvinyl alcohol fibrous binder were changed as shown in Table 3. . The strength, hiding properties, and paper-making properties of the obtained paper were as shown in Table 3.

[Table] As is clear from Table 3, if the amount of hollow polyester short fibers used is less than 5%, the paper strength and hiding properties will be poor, but if the amount of the polyester short fibers is 5% by weight or more, The characteristics were excellent. (Effects of the Invention) The polyester fiber paper of the present invention has high paper strength, high opacity and excellent hiding properties, and has an extremely soft texture. Therefore, it can be suitably used for clothing such as underwear, surgical gowns, medical materials, sanitary materials such as bottom sheets of sanitary napkins, impregnated paper for honeycombs, and the like.

[Brief explanation of the drawing]

FIGS. 1 to 5 are cross-sectional views showing examples of cross-sectional shapes of short polyester fibers used in the polyester fiber paper of the present invention. E...Hollow part.

Claims (1)

[Claims] 1. Single yarn fineness is 0.5 to 15 denier, single yarn length is 3 to 25 mm, has a hollow portion continuous in the fiber axis direction, and irreversibly elongates spontaneously in water at 90°C. A polyester fiber paper containing 5% by weight or more of short polyester fibers based on the total fiber components constituting the polyester fiber paper, which has a paper strength of 5.8 when the basis weight of the paper is 50 g/m ² A polyester fiber paper characterized by having a kg/5cm or more, a hiding property (opacity) of 65% or more, and a bending resistance of 7.5cm or less. 2. The polyester fiber paper according to claim 1, wherein the polyester short fibers have a hollowness ratio of 5% or more.