JP4645945B2 - Polyacrylonitrile-based transparent sheet and method for producing the same - Google Patents

Description

The present invention relates to a polyacrylonitrile-based transparent sheet comprising polyacrylonitrile-based fibers and / or fibrillated acrylic fibers, and a method for producing the same.

Polyacrylonitrile fiber has low Young's modulus, soft touch, soft feeling, vivid dyeability, good weather resistance, and has unique characteristics not found in other polymers such as hydrophilicity and lipophilicity. It is used in large quantities in the clothing field as one of the three major synthetic fibers. Recently, sheet-like materials such as paper and nonwoven fabric made of polyacrylonitrile fiber are also known. For example, Patent Document 1 discloses a sheet-like product using a thermal adhesive binder fiber made of acrylic fiber having thermal adhesiveness. Patent Document 2 discloses a sheet-like material formed by combining fibrillated acrylic fibers having a freeness of 450 ml or less and made of at least 97% by weight of acrylonitrile (AN) and polyacrylonitrile fibers. These sheets have excellent acid resistance and chemical resistance possessed by polyacrylonitrile fiber, and are excellent in strength, but are so-called paper made by ordinary paper making methods, and are naturally opaque and have low density. Met.
JP 2002-69744 A JP 2001-20195 A

As described above, a high-density sheet excellent in transparency made of polyacrylonitrile fiber and / or fibrillated acrylic fiber has not been obtained. An object of the present invention is to provide a sheet and a method for manufacturing the same that overcome such problems.

The inventor of the present invention has arrived at the present invention as a result of diligent study to achieve the above-mentioned object. That is, the present invention is achieved by the following means.
(1) polyacrylonitrile fibers及beauty hydrogel thread consists full Iburiru of acrylic fiber, 0.99 ° C. or higher, a sheet obtained by hot pressing treatment at a linear pressure of 150 kg / cm or more conditions, transparency of the sheet 60 % Or more and a density of 0.9 g / cm ³ or more.
(2) The polyacrylonitrile-based transparent sheet according to (1), wherein at least one surface of the sheet is film-like, and is composed of such a film-like layer and a fibrous layer.
(3) water-containing gel filaments of polyacrylonitrile fibers及beauty, a paper of a full Iburiru of acrylic fiber, 0.99 ° C. or higher, characterized in that the heat pressure treatment at a linear pressure of 150 kg / cm above conditions (1) Or the manufacturing method of the polyacrylonitrile-type transparent sheet as described in (2).

The polyacrylonitrile-based transparent sheet of the present invention maintains the performances such as heat resistance, chemical resistance and gas barrier properties inherent to the polyacrylonitrile-based polymer as they are, and has a high density and high transparency. In addition, since they can be easily controlled, they can be used for various purposes as paper or film.

The present invention is described in detail below. Polyacrylonitrile transparent sheet of the present invention, polyacrylonitrile fibers及beauty hydrogel thread consists full Iburiru of acrylic fiber, 0.99 ° C. or higher, be a sheet of heat pressure treatment at a linear pressure of 150 kg / cm or more conditions The transparency of the sheet is 60% or more, preferably 70% or more, and the density is 0.9 g / cm ³ or more, preferably 0.95 g / cm ³ or more.

The polyacrylonitrile polymer used for the polyacrylonitrile fiber of the present invention is a copolymer or acrylonitrile homopolymer containing at least 60% by weight, preferably 75% by weight, more preferably 85% by weight or more. is there. Copolymerization components include acrylic acid, methacrylic acid, crotonic acid, isocrotonic acid, itaconic acid, maleic acid, mesaconic acid, citraconic acid and their water-soluble salts (alkali metal salts, ammonium salts), allyl alcohol, methallyl alcohol , Oxypropion acrylonitrile, methacrylonitrile, α-methylene glutaronitrile, isopropenyl acetate, acrylamide, dimethylaminoethyl methacrylate, vinyl pyridine, vinyl pyrrolidone, methyl acrylate, methyl methacrylate, vinyl acetate, allyl chloride, methallyl Well-known ethylenically unsaturated compounds such as sodium sulfonate, sodium p-styrenesulfonate, and potassium p-styrenesulfonate can be exemplified.

The polyacrylonitrile fiber of the present invention composed of such a polyacrylonitrile polymer is dissolved in a normal solvent for acrylic fiber to form a spinning dope, and after wet spinning, washing with water and drawing, a water-containing solution that is not subjected to a densification drying step. it is a gel yarn. In addition, as a fineness, it is 0.1-20 dtex, Preferably it is 0.2-11 dtex.

The fibrillated acrylic fiber employed in the present invention can be obtained by beating the above-described polyacrylonitrile fiber with a beater or refiner, but the polyacrylonitrile polymer preferably has a higher acrylonitrile content, 97% by weight or more, most preferably a homopolymer. Moreover, it is preferable that the hydrogel yarn is beaten in order to improve beating ease or sheet strength.

Next, the manufacturing method of the transparent sheet of this invention is explained in full detail. First, polyacrylonitrile fiber and fibrillated acrylic fiber cut to a length corresponding to the purpose of about 1 to 30 mm are dispersed in water and subjected to normal wet papermaking or crimped polyacrylonitrile fiber. A web or non-woven fabric is produced by a known technique such as making a web with fibers, sprinkling fibrillated acrylic fibers and then performing a water punch or the like. After the paper or nonwoven fabric is dried, the transparent sheet of the present invention can be obtained by subjecting the paper or nonwoven fabric to hot pressing with a calender roll.

Such a production method uses polyacrylonitrile fiber and fibrillated acrylic fiber in combination, but the transparent sheet of the present invention can be produced with either polyacrylonitrile fiber or fibrillated acrylic fiber alone. . Even when used in combination as described above, the blending ratio is not particularly limited, but from the viewpoint of ease of production or dimensional stability, 5 to 80% by weight of fibrillated acrylic fiber is contained. Is preferred.

When the polyacrylonitrile fiber alone is produced, the transparent sheet of the present invention can be obtained by entanglement of a fine hydrous gel yarn with a water punch or the like, followed by hot pressing with a calender roll after drying. In addition, when producing fibrillated acrylic fiber alone, it is necessary to pay attention to breakage due to shrinkage, etc., but by carrying out normal wet papermaking and drying it with a calender roll, the transparent sheet of the present invention can be obtained. Obtainable.

Here, the heat pressure condition in the calender roll depends on the acrylonitrile ratio of the polyacrylonitrile-based polymer and the moisture content of the fiber used , but it must be 150 ° C. or higher and the linear pressure of 150 kg / cm or higher. The upper limit is 280 ° C, preferably 260 ° C.

The transparent sheet of the present invention may be blended with other inorganic fibers, organic synthetic fibers, inorganic powders, etc. depending on the purpose, as long as the density, transparency, etc. of the sheet are not hindered, and further resistant as required. A resin emulsion or the like can be applied or sprayed on the surface of the sheet in order to improve the electrolytic solution property.

The polyacrylonitrile-based transparent sheet of the present invention thus obtained has a transparency of 60% or more and a density of 0.9 g / cm ³ or more. Further, at least one surface of the sheet is film-like, and such film It is preferable that it consists of a fibrous layer and a fibrous layer. A sheet having such a structure can be obtained by setting the heat and pressure conditions in consideration of the acrylonitrile ratio of the acrylonitrile polymer, the moisture content of the fibers used, the basis weight of the paper, the basis weight of the nonwoven fabric, and the like. For example, using a hydrated gel yarn having an acrylonitrile ratio of 90% by weight and an internal moisture content of 30% to 400% by weight and a fibrillated acrylic fiber of acrylonitrile homopolymer, the basis weight of the paper is 10 to 50 g / m. ^In the case of ² , it can be obtained by setting the pressure to approximately 150 ° C. or higher and the linear pressure to 200 kg / cm or higher.

EXAMPLES Hereinafter, the present invention will be specifically described by way of examples. However, these are merely illustrative, and the gist of the present invention is not limited thereto. In addition, unless otherwise indicated, the part and percentage in an Example are shown on a weight basis. The measurement methods and evaluation methods in the examples are shown below.

[Internal moisture content of hydrous gel yarn]
It is calculated by using the following formula from the weight A after dehydrating the water-containing gel yarn sufficiently containing water for 2 minutes at an acceleration of 1000 G and the weight B after further drying the fiber.
Internal moisture content (% by weight) = [(A−B) / B] × 100

[Transparency]
Using a spectrophotometer V-570 manufactured by JASCO Corporation, the total light transmittance of a sheet having a wavelength of 380 to 780 nm was measured and defined as transparency.

[Production example of polyacrylonitrile fiber]
A monomer mixture consisting of 90 parts of acrylonitrile and 10 parts of methyl acrylate was subjected to aqueous suspension polymerization, and the resulting polymer was wet-spun using a concentrated aqueous solution of sodium rhodanate as a solvent.
Subsequently, washing with water and stretching were performed to obtain polyacrylonitrile fibers (fiber A and fiber B). The obtained fibers A and B had internal moisture contents of 40% and 38%, respectively, and the finenesses were 0.7 dtex and 0.4 dtex.

[Production example of fibrillated acrylic fiber]
Wet spinning was carried out using a concentrated aqueous solution of acrylonitrile homopolymer sodium rhodanate as a solvent. Subsequently, it was washed with water and stretched to obtain polyacrylonitrile fiber (hydrous gel yarn). Next, the polyacrylonitrile fiber was cut to 5 mm and beaten with a refiner to produce a fibrillated acrylic fiber having a Canadian standard freeness of 160 ml.

[Examples 1 to 5]
70 parts by weight of polyacrylonitrile fiber (fiber A or fiber B) cut to 6 mm and 30 parts of fibrillated acrylic fiber are uniformly dispersed in water, wet-made using a circular paper machine, and dried at 110 ° C. Three kinds of test papers having different basis weights were obtained. Subsequently, the test paper was subjected to heat and pressure treatment with a calender roll under the processing conditions shown in Table 1 to obtain Examples 1 to 5 of the polyacrylonitrile-based transparent sheet of the present invention. The measurement results of the transparency and density of the obtained transparent sheet are summarized in Table 1.

[Comparative Example 1]
The test paper used in Example 1 was subjected to heat and pressure treatment at a temperature of 120 ° C. and a linear pressure of 200 kg / cm to obtain a polyacrylonitrile-based sheet. The measurement results of transparency and density are also shown in Table 1.

Claims (3)

Polyacrylonitrile fibers及beauty hydrogel thread consists full Iburiru of acrylic fiber, 0.99 ° C. or higher, a sheet obtained by hot pressing treatment at a linear pressure of 150 kg / cm or more conditions, transparency of the sheet is 60% or more, A polyacrylonitrile-based transparent sheet having a density of 0.9 g / cm ³ or more. 2. The polyacrylonitrile-based transparent sheet according to claim 1, wherein at least one surface of the sheet has a film-like shape and comprises such a film-like layer and a fibrous layer. 3. Hydrogel filamentous polyacrylonitrile fibers及beauty, a paper of a full Iburiru of acrylic fiber, 0.99 ° C. or higher, to claim 1 or 2, characterized in that the heat pressure treatment at a linear pressure of 150 kg / cm or more conditions The manufacturing method of the polyacrylonitrile-type transparent sheet of description.