JPS61282500A - Polyester fiber paper - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to polyester fiber paper containing short polyester fibers, and more specifically, it has a property that, even though it is thin, it is difficult for liquids, gases, bacteria, etc. to pass through, it is strong, and it has a high opacity. The present invention relates to a polyester fiber paper that has excellent texture and a particularly soft feel.

(Conventional technology) Recently, with the changes in lifestyle and the advancement of technological innovation, the performance required for paper has become ■, and instead of conventional wood pulp, vinylon, nylon, polyacrylonitrile, polyester, etc. Synthetic fibers are increasingly being used as raw materials for paper. Paper made from synthetic fibers generally has excellent moisture resistance, weather resistance, and electrical insulation properties, so in the future,
Development in special fields is expected. Among these synthetic fibers, vinylon fibers and polyacrylonitrile fibers have traditionally been used in large quantities, but due to increasingly sophisticated performance requirements, various papers have recently been developed using polyester fibers, which have the best performance. is being attempted. However, conventional polyester fiber paper using short polyester fibers has the drawbacks of high basis weight, thick paper texture, and high paper fees. Therefore, if the fabric 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 opacity will be poor, making it unsuitable for use in clothing. Furthermore, the problem arises that liquids, gases, bacteria, etc. can easily pass through the material, making it unsuitable for use as surgical gowns, medical materials, and sanitary materials.

On the other hand, JP-A-55-110545 proposes an attempt to improve the electrical properties and tactile sensation of paper by using polyester fibers as threads with irregular cross-sections such as T-shapes, Y-shapes, and foot-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 the stretched polyester fibers are used, a slight improvement in the feel is observed, but the other problems mentioned above cannot be solved.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned various problems, and even if the thickness of the paper is reduced, the paper strength is high, liquids, gases, bacteria, etc. do not easily pass through, and the opacity is low. It is an object of the present invention to provide a polyester fiber paper which has excellent properties, has an extremely soft texture, and is suitable for clothing, surgical gowns, medical materials, sanitary materials, and the like.

(Means for Solving the Problems) The present invention has a single yarn fineness of 0.1 to 15 deniers, a single yarn length of 3 to 251111111%, a flatness of 2.5 or more, and This polyester fiber paper is characterized by containing short polyester fibers that spontaneously elongate irreversibly.

Polyethylene terephthalate is suitable as the polyester used in the present invention, but some of its acid components and/or diol components are isophthalic acid, cepatic acid, 5-
Copolymerized polyesters substituted with dicarboxylic acids such as sodium sulfoisophthalic acid and diols such as diethylene glycol, 1,4-butanediol, and polyethylene glycol may also be used. Furthermore, polybutylene terephthalate, polypropylene terephthalate, and the like are also preferably used. It goes without saying that matting agents, fluorescent whitening agents, antistatic agents, flame retardants, etc. may be added to these polyesters.

The polyester fibers contained in the polyester fiber paper of the present invention have a single filament fineness of 0.1 to 15 deniers, preferably 2
~8 denier, the length of the single yarn is 3~25111 m, preferably 5~15 mm. When the single yarn fineness exceeds 15 denier, the paper strength decreases and the texture becomes hard. When the single fiber fineness is less than 0.1 denier, dispersibility in water becomes poor and paper-making properties become poor. Furthermore, if the length of the single yarn is shorter than 3 mm, the paper strength will be insufficient, and if it exceeds 251 mm, the dispersibility in water will be poor and quality unevenness will occur.

Furthermore, the polyester short fibers contained in the polyester fiber paper of the present invention must have an oblateness of 2.5 or more, and more preferably within the range of 3.5 to 7.0. . As shown in Figure 3, the flatness is A/
It is represented by B. If the flatness is less than 2.5, the paper strength and opacity will not be improved, and the permeation of liquids, gases, bacteria, etc. will not be prevented. Figures 1 to 10 show examples of cross-sectional shapes of the polyester short fibers used in the present invention. In particular, as shown in Figures 2 to 10, the polyester staple fibers have irregularities on the cross-sectional periphery. Some are preferable because of their high opacity. Further, it is preferable to use flat hollow fibers as shown in FIG. 6 because they improve concealment properties and bulkiness.

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. 9
Polyester fibers that spontaneously stretch irreversibly in water at 0°C can be stretched at 85°C to 95°C after being stretched in a relatively low-temperature water bath.
By shrinking in a water bath, fibers with a low degree of oriented crystallinity are obtained.

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. It is also possible to use a mixture of such materials. 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. Additionally, a small amount of binder may be added. In such a case of mixed papermaking, it is desirable that the content of the above-mentioned short polyester fibers be 5% by weight or more in order to achieve the object of the present invention.

In addition, the single yarn fineness is 0.5 to 15 denier, and the single yarn length is 3 to 15 deniers.
251III11, undrawn polyester yarn having an obliqueness of 2.5 or more may also be used as a binder.

The polyester fiber paper of the present invention is usually produced by a wet papermaking method, but it can also be produced by a dry papermaking method, a spunbond method, or the like.

(Function) Since the polyester fiber paper of the present invention is made from polyester staple fibers having a flat cross-sectional shape and having a specific single yarn fineness, single yarn length, and flatness, it is necessary to The long axis direction of the cross section of the short fibers is arranged in a direction parallel to the paper surface. As a result, the gaps between the fibers on the paper surface are reduced, improving the hiding properties, ie, the opacity, and the ability to prevent the penetration of liquids, gases, bacteria, etc. Furthermore, since the short fibers have a flat cross-sectional shape, the contact area between the short fibers in the paper becomes large, which increases the frictional force when tearing the paper and improves the strength of the paper. In addition, since spontaneously extensible polyester short fibers are used, the polyester short fibers are elongated by heat treatment such as drying after paper making, and this, combined with the low orientation crystallinity, results in an extremely soft texture. Become.

(Examples) Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples.

In addition, the spontaneous elongation rate and crystallinity (specific gravity) of polyester short fibers, the paper strength, water repellency (liquid permeability), pressure loss (gas permeability), opacity, and bending resistance (
The method for measuring softness is as follows.

(1) Spontaneous elongation rate: A sample is treated in water at 90'C for 20 minutes, and the length after treatment is determined by the following formula.

and β is the length of the sample after treatment. Indicates length.

(2) Specific gravity: A sample is placed in a density gradient tube at 25° C. made of a mixed solvent of n-heptane and carbon tetrachloride, and the sedimentation value of the sample after 6 hours is read, and this is taken as the specific gravity.

(3) Using JIS-P paper strength crab constant speed extension type tensile testing machine
Measured according to the method of -8113.

(4) Ja aqueous: 0.1 cc of water was dropped on the surface of paper, and the time required for the entire amount to permeate into the nonwoven fabric was measured.

(5) Pressure drop: Measure the pressure drop when air is passed through at 4 CIIl per second.

(6) Opacity: Measured according to the method of J I 5-P-8138.

(7) Bending resistance: Measured according to the cantilever method.

Examples 1 to 12, Comparative Examples 1 to 5 Polyethylene terephthalate chips having an intrinsic viscosity of 0.65 were melted at 300°C and discharged at 285°C through a spinneret having 1200 nozzles shaped as shown in FIG. It was pulled at a speed of 1000m/win. On this occasion,
By varying the dimensions and discharge amount of the nozzle, undrawn yarns having the cross-sectional shapes shown in FIG. 4 with different flatness and fineness were obtained.
The tow was made into a 10,000 denier tow, stretched 2.8 times in water at 62°C, then shrunk by 40% in water at 95°C for 2 seconds, and cut into various lengths. The obtained short fibers were dispersed in water so that the fiber concentration was 0.5%, and at the same time, pulp and acrylic acid ester resin (binder) were added at the following blending ratio.

Blend ratio Polyester staple fiber: 50% Pulp: 30% Acrylic acid ester resin = 20% This dispersion was sent to a cylinder paper machine and processed in the usual manner to obtain a fabric weight of 50%.
g/rrr paper was obtained.

The spontaneous expansion/contraction rate, specific gravity, paper strength, opacity, pressure loss, bending resistance, and paper-making properties in the paper-making process of the obtained polyester staple fibers were as shown in Table 1.

(Hereinafter, this page margin) As is clear from Table 1, the polyester fiber papers of the present invention (Examples 1 to 12) have high paper strength, large opacity and pressure loss, excellent hiding properties, and high bending resistance. The texture was low, the texture was soft, and the paper-making properties were good.

On the other hand, when the single fiber fineness was less than 0.1 denier (Comparative Example 1), the dispersibility in water was poor, the papermaking properties were poor, and a satisfactory paper could not be obtained. On the other hand, when the single yarn fineness exceeded 15 denier (Comparative Example 2), the paper strength was low, the bending resistance was high, and the texture was hard. Furthermore, the length of the single yarn is 3m.
If it is less than 25 mm (comparative example 3), the paper strength decreases and
When it exceeded (Comparative Example 4), the dispersibility in water was poor (the paper-making properties were poor, the paper thickness was uneven, and a satisfactory paper could not be obtained).

Further, when the flatness was less than 2.5 (Comparative Example 5), the paper strength was low, the opacity and pressure loss were low, and the hiding property was poor.

Comparative Example 6 In Example 9, 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 9.

The strength of the obtained paper was low at 2.4 ktr/5 cm, the opacity was 58%, the pressure loss was low at 10 mm H20, and the hiding property was poor, and the bending resistance was 9.5 cm, making the texture poor. It was a little hard.

Comparative Example 7 In Example 9, paper was made under the same conditions as in Example 9 except that the paper was stretched at 2.8 times in hot water at 70°C, and then subjected to free shrink heat treatment in an atmosphere of 140°C.

The obtained short fibers do not elongate spontaneously, and in water at 90°C, 1.
It contracted by 3% and had a specific gravity of 1.375. The strength of the obtained paper was 6.5g15aa, the opacity was 67%, and the pressure loss was 21m+mH20, but the bending strength was 10
．． It was high at 5am, and the texture was a little hard.

Example 13 to Comparative Example 8 A polyethylene terephthalate copolymer copolymerized with 2.6 mol% of 5-sodium sulfoisophthalic acid and having an intrinsic viscosity of 0.48 was melted at 305°C, and nozzles of various shapes (No. 11, 12, and 13) through a spinneret having 500 holes.
It was discharged at a temperature of Each tow was converged into a 350,000 denier tow, stretched 3.0 times in water at 65°C, and then shrunk by 40% in water at 90°C for about 2 seconds.

These shrink-treated tows were heated in an atmosphere of 105°C for 10
After drying for a minute, it was cut to obtain polyester drawn short fibers having a single yarn fineness of 2 denier and a single yarn length of 10 vw.

On the other hand, the above-mentioned spun fibers with various cross-sectional shapes were cut into lengths of 10 mm without drawing, and the cross-sectional shapes and round cross-sectional shapes shown in FIGS. 1, 4, and 6 were obtained. Undrawn short polyester fibers having a fineness of 4 denier were obtained.

These drawn polyester short fibers and undrawn polyester short fibers with various cross-sectional shapes are combined as shown in Table 2 and dispersed in water so that the fiber concentration is 0.5%, and at the same time a fibrous polypropylene binder is mixed. was added.

The blending ratios of polyester drawn short fibers, polyester undrawn short fibers, and polypropylene binder were as follows.

Blend ratio Polyester stretched short fibers: 55% Polyester unstretched short fibers: 35% Fibrous polypropylene binder: 10% This dispersion was sent to a cylinder paper machine, and a paper having a basis weight of 50 g/rrr was obtained by the usual method.

The spontaneous elongation rate, specific gravity, strength, opacity, water resistance, bending resistance, and paper-making properties of the paper-making process of each polyester drawn short fiber were as shown in Table 2.

(Hereinafter, the margin of this page) As is clear from Table 2, the polyester fiber papers of the present invention (Examples 13 to 17) have high paper strength, high opacity and water repellency, and excellent hiding properties. The softness was low, the texture was very soft, and the paper-making properties were also good.

On the other hand, when using short fibers with a round cross section (Comparative Example 8
) had low paper tenacity, low opacity and water repellency, poor hiding power, high bending resistance and hard texture.

In addition, when the drawn short fibers have a flat cross section and the undrawn short fibers have a round cross section (Example 13.16), when both the drawn short fibers and the undrawn short fibers have flat cross sections (Example 14.15.1)
7), the purpose of the present invention can be achieved in any case, especially when the cross-sectional periphery of the short fibers has irregularities (Example 13)
．． 14, 16, and 17) have increased opacity.

(Effects of the Invention) The polyester paper of the present invention has high paper strength, low permeability to liquids, gases, bacteria, etc., high opacity and excellent hiding properties, and has an extremely soft texture. There is. 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 drawings]

Figures 1 to 10 are cross-sectional views showing examples of the cross-sectional shape of polyester short fibers used in the polyester fiber paper of the present invention, and Figure 11 is a cross-sectional view of fibers having the cross-sectional shape shown in Figure 4. FIG. 12 is a plan view showing the shape of a nozzle for spinning fibers with the cross-sectional shape shown in FIG. 1, and FIG. FIG. 3 is a plan view showing the shape of a nozzle for spinning shaped fibers. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8

Claims (3)

[Claims] (1) Single yarn fineness is 0.1 to 15 denier, single yarn length is 3 to 25 mm, flatness is 2.5 or more, and 90
A polyester fiber paper characterized by containing short polyester fibers that spontaneously elongate irreversibly in water at ℃. (2) The polyester fiber paper according to claim 1, in which the cross-sectional periphery of the polyester short fibers is uneven. (3) The polyester fiber paper according to claim 1 or 2, wherein at least a portion of the polyester short fibers are flat hollow fibers.