JPH08158159A - Production of raw fiber for acrylic nonwoven fabric - Google Patents

Abstract

PURPOSE: To obtain a acrylic raw fiber for a non-woven fabric, having self- fusibility and excellent in shape stability by a melt-spinning method using water as a plasticizer. CONSTITUTION: A spinning raw liquid comprising an acrylonitrile polymer and water as a plasticizer is mixed with a polymer, preferably polyethylene, polypropylene or polyvinyl chloride, as a polymer having thermal fusibility, and subsequently spun e.g. into a side-by-side type conjugate fiber to obtain the acrylic raw fiber for the non-woven fabric, excellent in shape stability, free from a remaining solvent, and having self fusibility in spite of the acrylonitrile fiber at a low cost. The method enables to save a solvent-recovering and purifying process and has a large industrial value. The water content of the acrylonitrile polymer is especially preferably 10-25wt.%. The thermally fusible polymer has preferably a melting point of 120-150 deg.C and a critical surface tension of 30-40dyne/cm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an acrylonitrile-based raw material for a nonwoven fabric by a melt-composite spinning method. More specifically, it is an acrylonitrile-based self-fusing agent and has a stable morphology. It is intended to provide a method for producing an excellent non-woven yarn.

[0002]

2. Description of the Related Art Acrylonitrile-based non-woven fabric is difficult to heat-bond because polyacrylonitrile has a melting point higher than its thermal decomposition temperature.
It depends on the physical confounding by water jet.

In addition, in the case of bonding, it is common to add additives such as a heat-melting resin and an adhesive, and in particular, heat-fusible fibers having a fiber form are mixed with a card and then necessary. Depending on the cross layer, entangle and then heat bond.

On the other hand, in Japanese Patent Publication No. 53-42830, a composite fiber using a component having a heat fusion property as a component on one side is prepared by the composite spinning method as in the present invention, and dimethylacetamide, dimethylformamide, dimethylsulfoxide, nitric acid. , A known method such as a zinc chloride, an aqueous solution of rhodanese, and the like, and a known spinning method of a wet type, a dry type, a semi-molten type, and a dry-wet type, and production of long fibers.

[0005]

In the case of a non-woven fabric produced by entanglement of single fibers without adhesion, physical external force may impair the uniformity of the non-woven fabric. Especially when using a non-woven fabric for a filter, as a result of pressure increase due to clogging,
Not only does the opening become large and the filtration accuracy decreases, the captured SS component permeates when there is a sudden pressure change, but the single fiber that is the base material of the non-woven fabric mixes into the secondary liquid side of the filtration. There is even a fear of doing it.

In addition, when a hot-melt resin or an adhesive is added, it is difficult to uniformly disperse the additive, and there are single fibers that are not adhered at all. Therefore, in the non-woven fabric application, there is a single fiber due to an external force such as a sudden pressure change. There is still the possibility of fiber loss. The method disclosed in Japanese Examined Patent Publication No. 53-42830 is an excellent method for solving the above problems, but since a solvent is used, the removal, recovery, and purification processes of the solvent are essential, and the process as a whole It will be a large one. As a result, it is undeniably economically disadvantageous. Further, when using an organic solvent as the solvent, high affinity of the solvent and polyacrylonitrile, also, it is difficult to remove the residual solvent in the product due to the high boiling point, in medical, food applications There are inherent problems such as safety concerns.

[0007]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that a melt-spinning method using water as a plasticizer imparts heat-bonding property to acrylonitrile fibers. In addition, they have reached the present invention by finding a manufacturing method in which there is no residual solvent. That is, the present invention is achieved by an acrylonitrile-based polymer containing water as a plasticizer, and a method for producing a raw yarn for an acrylic non-woven fabric, which is characterized by melt-spinning a polymer having heat fusion property. . Hereinafter, the present invention will be described in detail.

The acrylonitrile polymer used in the present invention is not particularly limited as long as it has a composition that melts water as a plasticizer, and an acrylonitrile homopolymer or a copolymer with a known monomer can be used. When it is necessary to carry out spinning at a relatively low melt spinning temperature or the whiteness of the final product is particularly important, a polymer having an acrylonitrile ratio of 95% by weight or less is preferable.

The comonomer used in the copolymerization is not particularly limited as long as it can be copolymerized with acrylonitrile, and alkyl acrylate, alkyl methacrylate,
Acrylic acid, methacrylic acid, methacrylonitrile, acrylamide, vinyl acetate, vinyl chloride, vinyl bromide, vinyl fluoride, vinyl alkylate, vinylidene chloride, vinylidene bromide, styrene, styrene sulfonic acid, allyl sulfonic acid, methallyl sulfone Acids, styrene sulfonates, allyl sulfonates, methallyl sulfonates, ethylene, propylene and the like can be used.

Next, regarding the ratio of water as a plasticizer to be added to the acrylonitrile polymer and the polymer, when the water content is 15% by weight or less, the melting point is lowered as the water content is higher, but it is 10% by weight or less. The melting point becomes 180 ° C. or higher and the polymer is markedly colored. When it is 15% by weight or more, the influence of the water content is small and the melting point becomes almost constant. Therefore,
The water content in the polymer is preferably 15% by weight or more, but when the water content is too high, the productivity is lowered, so that the range of 10% by weight to 25% by weight is particularly preferable.

The heat-fusible polymer which is the second component to be composite-spun with the acrylonitrile-based polymer described above has a melting point in the range of 120 ° C. to 150 ° C., preferably melt-spinning of the acrylonitrile-based polymer. Since the preferable temperature is 150 ° C. to 180 ° C., a material having a melting point in this temperature range is optimal. The melting point defined here is a melting point measuring device (M, manufactured by Shimadzu Corporation).
Melting point measured by M-2 type).

In order for the heat-fusible polymer to exhibit good adhesion to the acrylonitrile polymer, the heat-fusible polymer has a critical surface tension of 30 dyne / cm or more and 40 dyne or more.
/ Cm or less, and examples of such heat-fusible polymers include polyethylene, polypropylene, polyvinyl chloride, vinyl chloride-vinylidene chloride copolymer, and the like.

Next, as the composite spinning method, known methods such as a sea-island spinning method, a core-sheath spinning method and a side-by-side spinning method can be used. The ratio of the acrylonitrile-based polymer and the heat-fusible polymer is not particularly limited, but stable non-woven fabric strength can be obtained when the heat-fusible polymer is less than 5% by volume based on the workability when processing into a non-woven fabric. It is difficult and should preferably be combined with 5% by volume or more of a heat-fusible polymer.

[0014]

[Function] Water acts on polyacrylonitrile as a plasticizer because water, which cannot maintain its properties as structural water at high temperature, exhibits the original properties of water molecules, such as DMF and DMSO.
It seems to cut off the interaction between cyano groups as well as. Further, the reason why the acrylonitrile-based fiber having no melting point has self-adhesiveness according to the present invention is that a fiber made of a heat-fusible polymer is compounded in a part of the fiber, It exhibits self-adhesiveness by heat treatment at a temperature above the melting point.

[0015]

EXAMPLES Examples are shown below for facilitating the understanding of the present invention, but these are merely examples, and the gist of the present invention is not limited thereto.

Example 1 85% by weight of acrylonitrile and 15% of methyl acrylate
A spinning melt obtained by melting the copolymer A consisting of 50% by weight and water at a mixing ratio of 80% by weight to 20% by weight at 150 ° C. and 150 ° C.
The polyethylene melted in 1. was spun at a take-up speed of 30 m / min into a saturated steam of ² kg / cm ² from a spinneret with 100 holes using a side-by-side type composite spinning device while changing the volume ratio, and then in boiling water. 4 times stretched, 120
Short fiber denier 2.8 at a speed of m / min, total denier 28
A filament bundle of 0 was obtained. Dry the filament bundle 1
Table 1 shows the results of evaluation by tensile strength (strip method) and abrasion strength (universal method) after treatment with a heat roller at 40 ° C. When polyethylene was 5% by volume or more, good results were obtained, while when polyethylene was 4% by volume or less, tensile strength was good, but fiber peeling was observed in the abrasion strength test. Further, the copolymer A of 100% showed no adhesiveness at all.

[0017]

Reference Example 1 A copolymer B consisting of 90% by weight of acrylonitrile and 10% by weight of methyl acrylate and water were mixed at different weight ratios.
Otherwise, the fiber properties obtained as a result of melt spinning in the same manner as in Example 1 (however, polyethylene which is a heat-fusible polymer was not supplied, and the spinning temperature was set to the lower limit temperature that can be adopted) are shown in Table 2. Shown in. It was confirmed that when the mixing ratio of water was 10% by weight or less, the spinning temperature exceeded 180 ° C. and the coloring proceeded.

[0019]

Reference Example 2 Acrylonitrile (hereinafter, referred to as AN) and methyl methacrylate (hereinafter, referred to as MMA) were copolymerized at different mixing ratios (80% by weight of C) and 20% by weight of water as in Example 1. Table 3 shows the results of melt spinning by the method (however, polyethylene which is a heat-fusible polymer was not supplied, and the spinning temperature was set to the lower limit temperature that can be adopted). Coloring was observed when the AN ratio exceeded 95% by weight.

[0021]

[0022]

As described above, according to the method of the present invention, the acrylonitrile fiber itself is provided with the heat fusion property by the melt spinning method using water as the plasticity, and the fiber having no residual solvent is produced at a low cost. Is. For acrylic non-woven fabrics that overcome the problems of acrylic non-woven fabrics manufactured by conventional methods such as misalignment when used for filter applications, single fiber dropout, and safety due to residual solvent when used for food and sanitary materials In addition to providing the method for producing the raw yarn, the fact that a process capable of omitting the steps of solvent recovery and refining is provided is a remarkable effect of the present invention and has great industrial significance.

Continued Front Page (72) Inventor Ryuichi Kasahara 3-1-1-12 Kanaokahigashi-cho, Okayama City, Okayama Prefecture

Claims (1)

[Claims] 1. A method for producing a base yarn for an acrylic non-woven fabric, which comprises melt-compound spinning an acrylonitrile-based polymer containing water as a plasticizer and a polymer having a heat-melting property.