EP0423350A1

EP0423350A1 - Acrylic fiber of high thermal resistance, use of same and method of manufacturing same

Info

Publication number: EP0423350A1
Application number: EP90903406A
Authority: EP
Inventors: Toshihiro Yamamoto; Yasuaki Nakayama; Minoru Sasaki; Kenzi Arai; Yu Mihashi
Original assignee: Kanebo Ltd
Current assignee: Kanebo Ltd
Priority date: 1989-03-03
Filing date: 1990-02-27
Publication date: 1991-04-24
Also published as: WO1990010100A1; EP0423350A4

Abstract

This invention provides an acrylic fiber excellent in thermal resistance, creep resistance and transparency. The knit and union fabric produced from this fiber and, for example, an aromatic polyester fiber have clear color characteristics and soft hand inherent in the acrylic fiber. The acrylic fiber according to the present invention can be applied to electric blankets, electric carpets or waterproof cloths.

Description

TECHNICAL FIELD

The present invention relates to acrylic fibers with excellent heat resistance, their utility making use of, among others, that property and a method for producing the same.

BACKGROUND ART

Heretofore, acrylic fibers have been used widely for cloths, bedcloths and accessories, interiors and the like making good use of their clear color developability and soft hand and feel. However, because they have poor heat resistance such as permanent set and color change or deterioation after high temperature treatments, they cannot be used for transfer print jersey in the field of cloths and they have scarcely been able to be used as industrial materials.
For the purpose of improving the heat resistance of acrylic fibers, the following proposals have been made.
Japanese Patent Publication (Kokai) No. Sho 51-73587 discloses acrylonitrile fibers or films having crosslinking structures obtained by copolymerizing with acrylonitrile itaconic acid, butenetricarboxylic acid and a compound represented by the following formula

wherein R is H or C₁-C₄-alkyl, each in an amount of from 0.3 to 3 mole %.
Japanese Patent Publication (Kokai) No. Sho 53-126322 discloses fibers of acrylonitrile copolymers having a cyclic structure obtained by copolymerizing acrylonitrile as a main component with a hereto 1,6-diene compound having an oxygen atom, a sulfur atom or nitrogen atom as a hetero atom such as diallyl ether.
Also, Japanese Patent Publication (Kokai) No. Sho 53-126322 discloses fibers of acrylonitrile copolymers having a cyclic structure obtained by using a divinyl compound such as divinyl ether in place of the above-described hetero 1,6-diene compound.
As described above, in the conventional heat resistant acrylonitrile fibers, the improvement of the heat resistance has been contemplated by the introduction of crosslinking structures to cyclic structures.
On the other hand, Japanese Patent Publication (Kokai) No. Sho 49-94921 discloses a method for producing hygroscopic acrylic fibers by spinning a copolymer comprising no less than 85 % by weight of acrylonitrile and from 0.5 to 15 % by weight of 2-acrylamide-2-methylpropanesulfonic acid. Among the examples in the publication, there is disclosed a specific example in which a highly hygroscopic fiber having an equilibrium moisture content of 4.1 % at 20°C and at an RH of 65 % is obtained by dissolving in dimethylacetamide 30 parts of a copolymer (master batch) obtained by the copolymerization of 20 parts of 2-acrylmide-2-methylpropanesulfonic acid with 80 parts of acrylonitrile and 70 parts of a copolymer obtained by the copolymerization of 91 % by weight of acrylonitrile with 9 % by weight of methyl acrylate, followed by wet spinning, stretching, drying and heat shrinking.
Japanese Patent Publication (Kokai) No. Sho 54-34416 discloses hollow fibers formed from a copolymer comprising no less than 70 % by weight of acrylonitrile, from 1 to 30 % by weight of a copolymerizable compound having a sulfonic acid group or its salts and from 0 to 29 % by weight of a copolymerizable monomer. The publication discloses 2-acrylamide-2-methylpropanesulfonic acid as the copolymerizable compound having a sulfonic acid group or its salts, and it is described therein that the compound endows the resulting polymer with water absorption properties and resistance to thrombokinesis because it has a sulfonic acid group. The hollow fibers described in the publication are suitable for hemodialysis as pointed out therein.
Japanese Patent Publication (Kokai) No. Sho 56-128313 discloses side-by-side type two-component, self crimping acrylic fibers comprising a hydrophobic acrylonitrile copolymer component and a hydrophilic acrylonitrile copolymer component. The hydrophilic acrylonitrile copolymer contains from 0.7 to 1.2 mole % of 2-acrylamide-2-methylpropanesulfonic acid or its salts. The above-described two-component acrylic fibers described in the publication are endowed with crimping utilizing the hydrophilic acrylonitrile copolymer component has a relatively high hot water swell characteristics.
Japanese Patent Publication (Kokai) No. Sho 61-119711 discloses a high strength acrylic fibers containing from 0.1 to 1.0 mole % of a sulfonic acid group-containing compound selected from several specified sulfonic acids such as 2-acrylamide-2-methylpropanesulfonic acid and having an intrinsic viscosity of at least 2.0 and a tensile strength of no less than 10 g/d. According to the description in the publication, the fibers are not only strong but also have a strength retention ratio of no less than 70 % after the treatment with boiling water, and also having a high elasticity. It is described in the publication that the fibers can be used advantageously as a reinforcing material for cement, serving as a substitute for asbestos.
On the other hand, acrylic fibers have heretofore been used widely for cloths such as knits and jerseys, interiors such as carpets and curtains, and bedcloths and accessories such as blankets and sheets, and the like making good use of their clear color developability and soft hand and feel as referred to above. In the case of cloths among them, it has been necessary to dye them beforehand because they suffer permanent set due to heat to a great extent, thus deteriorating their dimension stability and hand and feel when they are dyed after having been knitted or woven.
For the purpose of overcoming the disadvantages, the following proposals have been made.
Japanese Patent Publication (Kokai) No. Sho 47-43557 discloses a method of manufacturing piece-dyed textile blend, union knitted or woven fabrics comprising an acrylic synthetic fiber and a polyester synthetic fiber wherein the content of the composite fiber in the acrylic synthetic fiber is from 20 to 50 % based on the total amount and the content of the polyester synthetic fiber is from 25 to 60 %, and the ratio of the shrinkage of the polyester synthetic fiber to the shrinkage of the acrylic synthetic fiber is 1:1-4. The publication discloses the use of a carrier which suffers less mutual contamination and a dying temperature of from 98 to 105°c.
Japanese Patent Publication (Kokai) No. Sho 49-1865 discloses a method of manufacturing piece-dyed union-knitted double knit fabrics comprising an acrylic spun yarn and a polyester long finished yarn, in which an acrylic spun yarn (A) comprising from 30 to 70 % of a composite fiber component and from 70 to 30 % of a non-composite fiber component and a polyester long finished yarn (B) are knitted to form a union knitted double knit fabric with a blend ratio of the polyester long finished yarn (B) being from 20 to 55 % and is used, and the ratio of the shrinkage of (B) to the shrinkage of (A) being 1:3-5, then piece-dyeing it at a dyeing temperature of from 96 to 105°C using a carrier giving less mutual contamination, and finishing it by feeding at a longitudinal overfeed ratio of from 18 to 25 % in the tentering step after the dyeing.
As described above, the conventional post-dyeable textile blend union knitted or woven fabrics comprising an acrylic fiber and a polyester fiber are those which are obtained by mixing a composite fiber in place of a portion of the acrylic fiber and dyeing at a low temperature using a carrier.
On the other hand, Japanese Patent Publication (Kokai) No. Sho 58-13739 discloses union knitted or woven fabrics comprising a polyester fiber substantially composed of a homopolymer of polyethylene terephthalate and which can be dyed at atmospheric pressure with a dispersed dye, and an acrylic fiber.
The above-described polyester fiber is a fiber which has not been bulk-processed and has an initial modulus at 30°C of no less than 55 g/d and a peak temperature (Tmax) of kinetic loss tangent (tan δ) at a measurement frequency of 110 Hz being no higher than 105°C, with the peak value of tan δ (i.e., [tan δ)max] exceeding 0.135, and/or a fiber which has been bulk-processed and which has an initial modulus at 30°C of no less than 55 g/d, with Tmax (°C) and (tan δ)max satisfying the formula: (tan δ)max ≧ (Tmax - 105) X 10⁻², and (tan δ)max being no less than 0.08. It is described that such fibers as described above are those fibers which are prepared by thermal treatment by dry heat at a temperature of from 220 to 300°C after having been spun at a high speed of no lower than 4,000 m/minute, for example, and/or those fibers which are obtained by thermal treatment by dry heat at a temperature of from 220 to 300°C after having been spun at a high speed of no lower than 4,000 m/minute, and then bulk-treated in the conventional manner.
Japanese Patent Publication (Kokai) No. Sho 58-87340 discloses union knitted or woven fabrics comprising a polyester fiber having substantially the same properties as the polyester fiber disclosed in the above-described Japanese Patent Publication (Kokai) No. Sho 58-13739, an acrylic fiber and animal hair fiber.
As described above, polyester fibers which are used for manufacturing union knitted or woven fabrics together with acrylic fibers and which can be piece-dyed at a low temperature without using any carrier are special ones produced by spinning at a high speed and subjecting to thermal treatment after the spinning.
Furthermore, acrylic fibers have been used widely for blankets or carpets, particularly home carpets on which men walk frequently with bare feet, making good use of their clear color developability, soft and warm hand and feel, and good heat retaining properties. On the other hand, electric heating blankets or carpets in which heaters are housed are also used widely. Because the conventional acrylic fibers have an insufficient fastness to heat and have a high elongation at a high temperature, they are disadvantageous in that they undergo color change or permanent set when they are used as a fabric base for electric heating blankets or a surface material for electric heating carpets. In order to improve the fabric base for electric heating blankets, the acrylic fibers must be used in combination with polyesters, wool and the like. The acrylic fibers have never been used as a surface material for electric heating carpets.
As is well known, the acrylic fibers have an excellent color developability, hand and feel or volume feeling. Therefore, if the above-described defects are overcome, the acrylic fibers can make good use of the above-described excellent characteristics even when used alone as a fabric base for electric heating blankets, and it can be easily supposed that the acrylic fibers can favorably compare with polyesters, polyamides or wool which are at present used actually as a surface material for electric heating carpets.
However, no acrylic fiber has ever been developed or known that is free of the above-described defects.
Heretofore, polyester fibers, polyamide fibers, vinylon fibers and the like have been used as a fabric base material for waterproof cloths such as tents, beach parasols, car covers and boat covers. Although they have an excellent weatherability and strength retention ratio, the acrylic fibers have scarcely been used for the above purposes because they have a poor resistance to creep and a poor fastness to light. Therefore, if the above-described defects can be overcome, it is expected that the acrylic fibers can favorably compare with polyester fibers, polyamide fibers or vinylon fibers as a material for waterproof cloths.

DISCLOSURE OF INVENTION

An object of the present invention is to provide new acrylic fibers.
Another object of the present invention is to provide new acrylic fibers which are excellent in their heat resistant characteristics, particularly dimension stability to heat and dyeing fastness to heat.
Still another object of the present invention is to provide new acrylic fibers which are excellent in resistance to creep.
Yet another object of the present invention is to provide new acrylic fibers having an excellent transparency.
A further object of the present invention is to provide new acrylic fibers which can be dyed in deep color and which can be dyed in deep to pale color without using retarding agents but causing no non-uniformity in dyeing.
Still further, an object of the present invention is to provide new acrylic fibers which have an appropriate strength and a relatively high elongation and is excellent in spinning properties.
Another object of the present invention is to provide a method for producing new acrylic fibers of the present invention.
Still another object of the present invention is to provide union knitted or woven fabrics made of an acrylic fiber and an aromatic polyester fiber.
Yet another object of the present invention is to provide a new acrylic fiber material which can be used for producing, together with an aromatic polyester fiber, a union knitted or woven fabric that can be piece-dyed under the same dyeing conditions as used for usual aromatic polyester fibers.
A further object of the present invention is to provide a union knitted or woven fabric made of a new acrylic fiber which is excellent in dimension stability to heat and has soft hand and feel and an aromatic polyester fiber.
Still further, an object of the present invention is to provide a surface material for electric heating carpets and a fabric base for electric heating blankets which contain an acrylic fiber which is excellent in dimension stability to heat and resistance to permanent set.
Another object of the present invention is to provide an acrylic waterproof cloth which is excellent in resistance to creep and fastness to light.
Other objects and advantages of the present invention will be apparent from the following description.
According to the present invention, the above-described objects and advantages of the present invention can be achieved firstly by an acrylic fiber characterized by

(A) comprising an acrylonitrile copolymer
- (a) being composed substantially of a polymerizable unit represented by the following formula (1)
  and a polymerizable unit represented by the following formula (2)
  wherein M is a hydrogen atom or a monoequivalent cation,
- (b) the polymerizable unit (2) occupying from 0.4 to 1.5 mole % based on the sum of the polymerizable units (1) and (2),
- (c) the acrylonitrile copolymer having a degree of polymerization in a range of from 600 to 1,500,
(B) the acrylic fiber having a tensile strength in a range of from 2 to 5 g/d, and
(C) the acrylic fiber having an elongation of no higher than 10% at 260°C with respect to a relationship between a temperature and an elongation while increasing the temperature.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 shows the relationship between the temperature and the elongation for the acrylic fiber of the present invention and the corresponding conventional acrylic fiber;
Fig. 2 a schematic view of the apparatus used for the measurement of the relationship shown in Fig. 1;
Fig. 3 is a schematic view of the sample stand used when the degree of crystallization of the acrylic fiber of the present invention is measured.
Fig. 4 shows the relationship between the temperature and the elongation for the acrylic fiber used in the union woven fabric of the present invention and for the corresponding conventional union woven fabric;
Fig. 5 shows the relationship between the temperature and the elongation for the acrylic fiber used as a surface material for electric heating carpets in the present invention and for the corresponding conventional acrylic fiber;
Fig. 6 shows the relationship between the temperature and the elongation for the acrylic fiber used as a fabric base for electric heating blankets in the present invention and for the corresponding conventional acrylic fiber; and
Fig. 7 shows the relationship between the temperature and the elongation for as a surface material for electric heating carpets in the present invention and for the corresponding conventional acrylic fiber.

BEST MODE FOR CARRYING OUT THE INVENTION

As described above, the acrylic fiber of the present invention is identified by the requirement (A) which identifies the polymer constituting it, the requirement (B) identifying its strength, and the requirement (C) identifying its elongation at a high temperature.
With respect to the requirement (A), the polymer is composed substantially of the polymerizable unit represented by the above-described formula (1) derived from acrylonitrile and the polymerizable unit represented by the above-described formula (2) derived from 2-acrylamide-2-propanesulfonic acid (hereafter, abbreviated as "AMSP") or its salts.
The proportion of the polymerizable unit (1) and the polymerizable unit (2) is such that the polymerizable unit (2) occupies from 0.4 to 1.5 mole % based on the sum of the polymerizable units (1) and (2) (i.e., the polymerizable unit (1) is from 99.6 to 98.5 mole %). The polymerizable unit (2) is preferably from 0.6 to 1.2 mole % based on the same basis (i.e., the polymerizable unit (1) is from 99.4 to 98.8 mole %). If the proportion of the polymerizable unit (2) is below 0.4 mole %, gelling tends to occur in the polymerization step and it becomes difficult to perform deep color dyeing because of lack of dyeing sites. On the other hand, if it exceeds 1.5 mole %, the heat resistant characteristics described are deteriorated.
Further, with respect to the requirement (A), the above-described polymer has a degree of polymerization in a range of from 600 to 1,500. Preferred degree of polymerization is from 800 to 1,100.
If the degree of polymerization is below 600, the strength which ordinary acrylic fibers cannot be obtained while if it exceeds 1,500, gelling tends to occur in the polymerization step and the viscosity is too high to conduct ordinary wet spinning.
As for the requirement (B), the acrylic fiber of the present invention has a tensile strength of from 2 to 5 g/d, which is not so high and is an appropriate tensile strength for fibers for clothing. Preferred tensile strength is from 3 to 4 g/d. If the tensile strength is below 2 g/d, cutting of fibers tends to occur in the ordinary spinning step while the tensile strength of exceeds 5 g/d is too high to provide a sufficient tensile elongation referred to hereinbelow, and to give an elongation sufficient for spun yarns.
With respect to the requirement (C), the acrylic fiber of the present invention has an elongation of no higher than 10% at 260°C with respect to the relationship between the temperature and the elongation while increasing the temperature. Preferred elongation is no higher than 6%.
The acrylic fiber of the present invention has a feature that it is excellent in heat resistance and undergoes less permanent set as compared with the conventional acrylic fiber for clothing having the same level of tensile strength.
The acrylic fiber of the present invention may be crimped or without crimp. Preferably, the acrylic fiber of the present invention has the following characteristics.
The shrinkage factor after dry heat relaxation at 210°C is preferably no higher than 3%, and more preferably no higher than 1%.
With respect to the heat resistance when wet heating, the shrinkage factor after wet heat at 130°C is preferably no higher than 3%, and more preferably no higher than 1%.
As identified in the above-described requirement (B), the acrylic fiber of the present invention has a strength appropriate for ordinary fibers for clothing, and can show an elongation that can give good spinning ability at that strength. Preferred elongation is no lower than 35%, and more preferred elongation is from 35 to 60%.
The acrylic fiber of the present invention is desirable in that it can show an excellent transparency in contrast to general acrylic fibers, particularly those acrylic fibers obtained by wet spinning using organic solvents which show only a poor transparency. The acrylic fiber of the pressent invention shows a transparency of preferably at least 80%, and more preferably at least 90% according to the measurement method described hereinbelow.
The acrylic fiber of the present invention can have a Young's modulus of preferably from 400 to 700 kgf/mm², and more preferably from 500 to 600 kgf/mm².
The excellent heat resistant characteristics of the acrylic fiber of the present invention are supported by the fact that its dyeing fastness to heat (dry heat 120°C X 48 hours) is preferably at least class 3, and more preferably at least class 3.5.
The acrylic fiber of the present invention has a degree of crystallization of preferably from 20 to 40%, and more preferably from 25 to 35%.
As identified in the requirement (A), the acrylic fiber of the present invention contains the polymerizable units (1) and (2) such that the polymerizable unit (2) is from 0.4 to 1.5 mole % based on the sum them. The investigation by the present inventors has revealed that the above-described objects and advantages of the present invention can be retained even when a little amount of an other polymerizable unit (3) is added under the conditions where the above-described proportion of the polymerizable units (1) and (2) is retained.
Therefore, secondly, the present invention provides an acrylic fiber characterized by

(A') comprising an acrylonitrile copolymer
- (a') being composed substantially of the polymerizable unit represented by the above-described formula (1), the polymerizable unit represented by the above-described formula (2), and a polymerizable unit represented by the formula (3) derived from a monomer copolymerizable with acrylonitrile other than the polymerizable unit represented by the formula (2),
- (b') the polymerizable unit (2) occupying from 0.4 to 1.5 mole % based on the sum of the polymerizable units (1) and (2), and the polymerizable unit (3) occupying no more than 5 % by weight based on the polymerized polymer (1),
- (c) the acrylonitrile copolymer having a degree of polymerization in a range of from 600 to 1,500,
(B) the acrylic fiber hving a tensile strength in a range of from 2 to 5 g/d, and
(C) the acrylic fiber having an elongation of no higher than 10% at 260°C with respect to a relationship between a temperature and an elongation while increasing the temperature.

With respect to the requirement (A), there is present in addition to the polymerizable units (1) and (2), a polymerizable unit represented by the formula (3) derived from a monomer copolymerizable with acrylonitrile other than the polymerizable unit represented by the formula (2) in an amount of no more than 5 % by weight based on the polymerizable unit (1).
As for the polymerizable unit (3), there can be cited, for example, a unit represented by the following formula (3)

wherein R is a hydrogen atom or a methyl group; and Y is a group selected from the class consisting of a group of formula -COOX (where X is a hydrogen atom, a sodium atom or a methyl group), -OCOCH₃, -CONH₂, -C₆H₅, -CH₂SO₃Na and -C₆H₄SO₃Na.
With respect to the second acrylic fiber of the present invention, it should be understood that the description on the first acrylic fiber of the present invention is applicable to other points than described above.
The acrylic fibers of the present invention can be produced from the above-described acrylonitrile copolymers identified by (A) or (A') by the following method, which is a method for producing an acrylic fiber characterized by:

(1) extruding a stock spinning solution of the acrylonitrile copolymer identified by (A) or (A') above through orifices of a spinneret to form fine streams of the stock spinning solution;
(2) stretching the fine streams by from 5 to 10 times while coagulating them to form spun filaments;
(3) heating the spun filaments to shrink them at a ratio of 3 to 25%; and
(4) subjecting the resulting shrunk filaments to a drying step.

The acrylonitrile copolymer which is used in the present invention can be produced by copolymerizing acrylonitrile with 2-acrylamide-2-methylpropanesulfonic acid (AMPS) or its salts, or by copolymerizing acrylonitrile, AMPS and an other monomer copolymerizable with acrylonitrile.
As for the salts of AMPS, there can be cited, for example, sodium salt (hereafter, sometimes abbreviated as "SAMPS"), potassium salt, 1/2 calcium salt and ammonium salt.
Preferred examples of the other monomer copolymerizable with acrylonitrile are those compounds represented by the following formula (3)'

wherein R and Y have the same meanings as defined in the formula (3).
As for the compounds represented by the formula (3)', there can be cited, for example, acrylic acid, methacrylic acid, their sodium salts, their methyl esters, vinyl acetate, acrylamide, methacrylamide, styrene, sodium allylsulfonate, sodium methacrylsulfonate and sodium styrenesulfonate. The other monomers copolymerizable with acrylonitrile can be used singly or two or more of them can be used together.
The polymerizable method for the acrylonitrile polymer may be any known method such as aqueous polymerization, emulsion polymerization, solution polymerization and the like.
The stock spinning solution used in the step (1) of the method of the present invention can of course be prepared by dissolving the thus-obtained acrylonitrile copolymer in a solvent. It may also be a polymerization reaction solution which contains the polymer obtained as a result of the polymerization reaction. In the latter case, it is desirable to use the polymerization reaction system which can serve as a stock spinning solution for wet spinning by merely recovering therefrom unreacted monomers.
The spinning method in the step (1) may be any known method such as wet spinning, dry wet spinning, dry spinning and semi-molten spinning. Among them, preferred are wet spinning and dry spinning. These spinning methods are known in themselves. For example, as for the wet spinning, those methods are adopted which are disclosed in Japanese Patent Publication (Kokoku) No. Sho 57-167,410, Japanese Patent Publication (Kokai) No. Sho 57-167,411, Japanese Patent Publication (Kokai) No. sho 57-217,011, Japanese Patent Publication (Kokai) No. Sho 57-113,410 and Japanese Patent Publication (Kokai) No. Sho 58-132,107. Details thereof are described in Examples 1 to 10 described later on. On the other hand, as for the dry method, those methods are adopted which are described in Japanese Patent Publication (Kokoku) No. Sho 49-1,665 and Japanese Patent Publication (Kokai) No. Sho 59-21,711, and as for the dry wet method method, those methods are used which are described in Japanese Patent Publication (Kokai) No. Sho 51-92,316 and the like. Detailed description are made on these methods in Examples 11 and 12 described later on.
Regardless of the spinning method used, the stock spinning solution is extruded from the spinneret to form fine streams of the stock spinning solution in the step (1). In the wet spinning, the fine streams are extruded into a coagulating solution while in the dry spinning the fine streams are extruded in a high temperature gas atmosphere, and in the dry wet method, the fine streams are extruded in a gas atmosphere and thereafter introduced into a coagulating solution.
According to the present invention, the fine streams are stretched by from 5 to 10 times while they are being coagulated in the step (2). The stretching can be carrie dout in one step or in multiple steps. In the multiple step stretching, the stretch ratio of each step may be selected appropriately so that the total stretch ratio can be in a range of from 5 to 10 times. Preferred stretch ratio is from 6 to 8 times. If the stretch ratio is below 5 times, the tensile strength of the fiber is insufficient, and on the other hand, if it exceeds 10 times, cutting of monofilament tends to occur and the filaments tend to be converted into fibrils.
The spun filaments obtained in the step (2) are then introduced in a heating process in the step (3) after being optionally subjected to a washing step (in the case of the wet spinning and dry wet spinning) or oiling.
In the step (3), the spun filaments are heated to shrink them at a ratio of from 3 to 25%. If the shrinkage ratio is below 3%, the tensile elongation of the fiber is insufficient while if it exceeds 25%, drying at a high temperature is necessary, which is uneconomical.
In the case where the spinning in the step (1) is carried out by wet spinning, the shrinking can be practiced using hot water or wet heat before so-called pre-drying step, i.e., before subjecting the spun filaments to crimper, in the pre-drying step.
The shrunk filaments obtained are then dried in the step (4). When the shrinking is carried out in the so-called pre-drying step or before it, the step (4) corresponds to so-called post-drying which is practiced after subjecting to crimping, if desired. The thus-obtained acrylic fiber of the present invention is cut to a predetermined length with a cutter, if desired.
As will be well understood from the above explanation, the most important feature of the present invention is that a specified acrylonitrile copolymer is used and heat shrinking at a ratio of from 5 to 25% is effected on the spun filaments therefrom before drying them. This feature of the present invention has never been known.
In view of the fact that the acrylic fiber of the present invention has a feature that it is excellent in heat resistant characteristics and its so-called permanent set in a high temperature environment is less, the present invention provides further union knitted or woven fabrics composed of the acrylic fiber of the present invention and an aromatic polyester fiber.
The union knitted or woven fabrics of the present invention can be dyed at dying temperatures used for ordinary aromatic polyester fibers.
While the aromatic polyester fiber which is used in the union knitted or woven fabric composed of the acrylic fiber of the present invention and the aromatic polyester fiber is not limited particularly, and preferred examples thereof include polyethylene terephthalate which contains ethylene terephthalate as a main repeating unit, polyhexamethylene terephthalate which contains hexamethylene terephthalate as a main repeating unit, polytetramethylene terephthalate which contains tetramethylene terephthalate as a main repeating unit, poly-(1,4-dimethylcyclohexane terephthalate) which contains 1,4-dimethylcyclohexane terephthalate as a main repeating unit, and polypivalolactone which contains ring opening product of pivalolactone as a main repeating unit. The polyesters may be homo- or co-polyesters. As for the co-polyester, there can be cited, for example, co-polyesters composed of ethylene terephthalate as a main repeating unit and ethylene isophthalate as a sub repeating unit (for example, no more than 10 mole % based on the total repeating units). Another example of the co-polyester is polyethylene terephthalate which contains no more than 5 mole % based on the total repeating units of ethylene 5-sodiumsulfoisophthalate. More preferred example of the aromatic polyester fiber includes homo- or co-polyester of ethylene terephthalate which contains ethylene terephthalate as a main repeating unit. The aromatic polyester fiber may be a conjugate fiber with same or different type aromatic polyester fiber, or a conjugate fiber with an other material such as a polyaramide fiber. The polyester fiber may be either filament or staple.
The structure of the union knitted fabric of the present invention may be double knit or single knit and is not limited particularly. For example, plating, fleecy knitting, smooth knitting, sheeting and the like are preferred. The structure of the union woven fabric of the present invention is not limited particularly, and preferably is, for example, plain weave, diagonal weave and double weave.
The dyeing of the union knitted or woven fabric composed of the acrylic fiber and aromatic polyester fiber according to the present invention can be carried out by 1-bath dyeing under high temperature conditions using, for example, a disperse dye and a cation dye (for acrylic fibers) in the case where the aromatic polyester fiber is a homopolymer of ethylene terephthalate which contains ethylene terephthalate as a main repeating unit.
Furthermore, the present invention provides a surface material for electric heating carpets and a fabric base for electric heating blankets, respectively, containing the above-described acrylic fiber of the present invention.
The surface material for electric heating carpets of the present invention is characteristic of containing the above-described novel acrylic fiber having an excellent performance. The acrylic fiber is contained in the surface material in an amount of, preferably, at least 10 % by weight, and more preferably at least 30 % by weight.
The surface material which contains the acrylic fiber in an amount of at least 10 % by weight is advantageous in that it can make good use of clear color developability and warm hand and feel which acrylic fibers have. As for the fiber to be used in combination with the acrylic fiber, there can be cited, for example, fibers having good heat resistance such as wool, polyester and nylon.
The present invention also provides an electric heating carpet using the above-described surface material of the present invention on the outermost surface or outer surface.
The structure of the surface material may be of any known type, for example, fabrics such as nonwoven fabric obtained as by needle punching and pile fabric as by tufting, or knitted webs as the case may be.
The electric heating carpet of the present invention may be of an integral heater type or of a separate type in which the body of the heater and the cover carpet are provided separately.
The fabric base for electric heating blankets of the present invention is characteristic of containing the above-described new acrylic fiber having an excellent performance. Such acrylic fiber is used in the fabric base in an amount of, preferably, at least 50 % by weight, and more preferably at least 70 % by weight.
The fabric base which contains at least 50 % by weight of the acrylic fiber is advantageous in that it can make good use of clear color developability and soft hand and feel which acrylic fibers have. As for the fiber to be used in combination with the acrylic fiber, there cna be cited, for example, polyester, wool, nylon and other acrylic fibers.
The present invention also provides an electric heating blanket using the above-described fabric base of the present invention.
The structure of the fabric base may be of any known type, for example, raised fabric and nonwoven fabric.
Furthermore, the present invention provides a hitherto unknown base cloth for waterproof cloths which makes a good use of the weatherability inherent to the new acrylic fiber of the present invention and which is excellent in resistance to creep, fastness to light.
The base cloth for waterproof cloths of the present invention is made of a cloth of the above-described acrylic fiber. The cloth includes sheet-form structures such as ordinary woven fabric, knitted fabric and nonwoven fabric. The sheet-form structures can be produced by various methods known in themselves.
The waterproof processing of the sheet-form structures can be practiced by known methods using known waterproofing agents.
As for the waterproof agent, there can be used preferably fluorine resins and silicone resins, for example, for air-permeable waterproof cloths while in the case of air-nonpermeable waterproof cloths, acrylic resins, vinyl chloride resins and the like, for example, are preferred.

EXAMPLES

Hereafter, the present invention will be described in detail by way of examples. Unless otherwise indicated specifically, all parts and %'s are parts by weight and % by weight. In the description of the present invention and examples, analytical methods, measurement methods and definitions of various physical properties are as follows.

Composition of Polymers

1) In the case where the polymerizable unit (3) has no -SO₃Na, the following method is used.
- i) The proportion α₁ (% by weight) of the polymerizable unit represented by the formula (2)
  wherein M is a hydrogen atom or a monoequivalent cation, in the polymer is obtained by the following measurement and calculation. Firstly, the polymer A (about 1 g) was weighed precisely and dissolved in dimethylformamide (special grade according to JIS). then, the solution was mixed with a highly acidic type cation exchange resin (50 to 100 mesh; 3 g) and stirred for 1 hour. Thereafter, the resin was filtered off using a glass filter. The filtrate was titered with 1/50 N NaOH in a potentiometric titrating apparatus (COM-101 type, manufactured by Hiranuma Sangyo Co., Ltd.). Under the same conditions blank tests were conducted to make corrections. α₁ (% by weight)
  wherein
  
  A₁;
  
  amount of polymer (g),
  
  B₁;
  
  titer of the sample with 1/50 N NaOH (ml),
  
  C₁;
  
  titer of the sample for blank test with 1/50 N NaOH (ml),
  
  D₁;
  
  molecular weight of the polymerizable unit (2), and
  
  f₁;
  
  strength of 1/50 N NaOH.
- ii) The proportion β₁ (% by weight) of the polymerizable unit represented by the formula (3)
  wherein
  
  R;
  
  a hydrogen atom or a methyl group,
  
  Y;
  
  -COOX, -OCOCH₃, -CONH₂, -C₆H₅,
  
  X;
  
  a hydrogen atom, a sodium atom or a methyl group
  
  in the polymer is obtained by the following measurement and calculation. Firstly, 0.5 g of the polymer A was dissolved in dimethylformamide (special grade according to JIS) to form a solution of a concentration of 50 g/l. Using a liquid cell made of CaF₂, dimethylsulfoxide as a reference, infrared spectra in a region of from 2,500 to 1,850 cm⁻¹ and from 1,850 to 1,500 cm⁻¹ were recorded with an infrared spectrophotometer (IR-430 type, manufactured by Shimazu Seisakusho Co., Ltd.). After effecting base line correction, the optical density of the polymerizable unit (3) (the C=O stretching vibration absorption band at 1,500 to 1,800 cm⁻¹ is used in the case where Y has -CO-, or the =C-H extraplanar deformation vibration absorption band at 1,500 to 1,700 cm⁻¹ is used in the case where Y has -C₆H₅, and the proportion of the optical density of the polymerizable unit (3) to the optical density of the absorption band at 2,240 cm⁻¹ of the polymerizable unit (1) was obtained using a standard curve prepared by mixing a homopolymer of the polymerizable unit (1) and a homopolymer of the polymerizable unit (3) in various proportions and determining ratios of the optical densities thereof according to the above-described method.
- iii) the proportion (% by weight) which the polymerizable unit (1) occupies in the polymer is γ₁ = 100 - (α₁ + β₁), and using these, the composition of the polymer was calculated according to the following formula.
  $γ₁'/β₁'/α₁' = (K₁₁/53.06)/(K₁β₁/E₁)/K₁α₁/D₁)$
  
  wherein γ₁' and γ₁; the proportion which the polymerizable unit (1) occupies in the polymer (mole %) and that (% by weight),
  β₁' and β₁; the proportion which the polymerization unit (3) occupies in the polymer (mole %) and that (% by weight),
  α₁' and α₁; the proportion which the polymerizable unit (2) occupies in the polymer (mole %) and that (% by weight),
  
  E₁;
  
  molecular weight of the polymerizable unit (3)
  
  D₁;
  
  molecular weight of the polymerizable unit (2)
  
  K₁;
  
  1/{γ₁/53.06) + (β₁/E₁) + (α₁/D₁)}
2) In the case where Y in the polymerizable unit (3) is -CH₂SO₃Na or -C₆H₅SO₃Na, the following method is used.
- i) The proportion α₂ (% by weight) which the polymerizable unit (2) occupies in the polymer was obtained by the following measurement and calculation.
  The measurement and calculation were carried out according to the method 1)-ii). In this case, the optical density of the polymerizable unit (2) was at 1,666 cm⁻¹ band and a homopolymer of the polymerizable unit (2) was used instead of the homopolymer of the polymerizable unit (3) for the preparation of the standard curve.
- ii) The proportion β₂ (% by weight) which the polymerizable unit (3) occupies in the polymer was obtained by the following measurement and calculation.
  The measurement and calculation were carried out according to the method 1)-i).
  
  wherein
  
  A₂;
  
  amount of polymer (g),
  
  B₂;
  
  titer of the sample with 1/50 N NaOH (ml),
  
  C₂;
  
  titer of the sample for blank test with 1/50 N NaOH (ml),
  
  D₂;
  
  molecular weight of the polymerizable unit (3), and
  
  f₂;
  
  strength of 1/50 N NaOH
- iii) The composition of the polymer (molar ratio) was calculated according to the method 1)-iii).
  $γ₂'/β₂'/α₂' = (K₂γ₂/53.06)/(K₂β₂/E₂)/K₂α₂/D₂)$
  
  wherein γ₂' and γ₂; the proportion which the polymerizable unit (1) occupies in the polymer (mole %) and that (% by weight),
  β₂' and β₂; the proportion which the polymerizable unit (3) occupies in the polymer (mole %) and that (% by weight),
  α₂' and α₂; the proportion which the polymerizable unit (2) occupies in the polymer (mole %) and that (% by weight),
  
  E₂;
  
  molecular weight of the polymerizable unit (3)
  
  D₂;
  
  molecular weight of the polymerizable unit (2)
  
  K₂;
  
  1/{(γ₂/53.06) + (β₂/E₂) + (α₂/D₂)}

Degree of Polymerization

Firstly, about 0.2 g of the polymer was dissolved in about 50 ml of dimethylformamide (special grade according to JIS) to form a solution of a concentration of C' 9 g/l). Using an Ostwald type viscometer in a constant temperature bath kept at 30°C, time A in second in which the above solution falls and time B in second in which dimethylformaldehyde falls were measured.
The degree of polymerization P was obtained according to the following calculation.
Relative viscosity: η rel = A/B
Specific viscosity: η sp = η rel - 1
Viscosity average molecular weight:
$Mη = (ηsp/C)/1.5 x 10⁻⁴$

$P = Mη/ \bar{m}$

wherein γ, the proportion which the polymerizable unit (1) occupies in the polymer (mole %) and that (% by weight),
β; the proportion which the polymerizable unit (3) occupies in the polymer (mole %) and that (% by weight),
α; the proportion which the polymerizable unit (2) occupies in the polymer (mole %) and that (% by weight),

E;: molecular weight of the polymerizable unit (3), and
D;: molecular weight of the polymerizable unit (2).

Relationship Between temperature and Elongation Measured While Increasing the Temperature

Fig. 2 illustrates the apparatus used. A loop of 80 mm long was made of a fiber of about 30 d in total (40 mm after doubling, 2), and these were retained in a heating cylinder 1 with upper and lower ends opened in the air using a clip 3. A load of 25 mg/d (about 1,500 mg, 4) was suspended below the heating cylinder with a wire rod. Then, the temperature was elevated from about 30°C at a rate of 40°C/minute on average and the position of the load was monitored by a camera 5 and recorded together with the temperature. Fig. 1 shows the relationship measured in this method for several acrylic fibers. The elongation ratio (%) was calculated by (dislocation of load [m/m]/40 [m/m]) X 100.

Shrinkage Ratio After Relaxation

A fiber bundle of about 600 m/m was prepared using about 9,000 d in total of a fiber, and was marked thereon at a distance of 500 m/m with suspending a load of 0.1 g/d (about 900 g) at room temperature. After removing the load, the fiber bundle was treated at 210°C for 30 minutes in the case of the dry process or at 130°C for 10 minutes in the case of the wet heat process without applying tension thereto. After cooling to room temperature, a load of 900 g was again applied to the fiber bundle and the distance A between the marks (m/m) was measured. Shrinkage ratio after relaxation (%) was calculated according to: {(500 - A)/500} X 100.

Fastness of Dyeing to Heat

1) Acrylic fiber

The fiber cut to from 30 to 150 m/m was degreased 3 times in warm water at about 60°C at a bath ratio of 1:200. In a dye solution adjusted to a pH of about 4.5 with acetic acid/sodium acetate (dye grade, owf was shown in Table 1) was introduced the fiber at about 60°C at a bath ratio of 1:100, and treated in a cycle of temperature elevation to 85°C (about 25 minutes) - retention at 85°C (about 10 minutes) - temperature elevation to 98°C (about 15 minutes) - retention at 98°C (about 10 minutes).
Next, after cooling it to about 40°C, the above-described fiber was washed with water at room temperature 3 times at a bath ratio of 1:200. Thereafter, it was treated in a cycle of dehydration by centrifugation - oiling (about 40°C, bath ratio: 1:200, production step oiling agent of the above-described fiber) - dehydration (the above-described oiling agnet owf 0.3%) - drying of about 80°C X 3 hours. After cooling it to room temperature, the fiber was hand card opened, which was then treated by dry heat 120°C X 48 hours. After cooling the fiber to room temperature, the change or deterioration of color of the fiber was judged by means of a gray scale for the measurement of the change or deterioration of color (JIS L0804) and using a color scale for the measurement of the change or deterioration of color as an auxiliary. Judgement was indicated by the range between the good and the bad.

2) Fabric Base for Electric Heating Blankets

A fabric bse cut to a piece of 20 cm square was treated by dry heat 120°C X 48 hours. Then, after cooling it to room temperature, the change or deterioration of color of the fabric base was judged by means of a gray scale for the measurement of the change or deterioration of color (JIS L0804) and using a color scale for the measurement of the change or deterioration of color as an auxiliary.

3) Surface Material for Electric Heating Carpets

A carpet cut to a piece of 20 cm square was treated by dry heat 120°C X 48 hours. Then, after cooling it to room temperature, the change or deterioration of color of the carpet was judged by means of a gray scale for the measurement of the change or deterioration of color (JIS L0804) and using a color scale for the measurement of the change or deterioration of color as an auxiliary.

Tensile Strength, Elongation and Young's Modulus

These were measured using a constant speed tensile tester (UTM-II type, manufactured by Toyo Baldwin) according to JIS L1015.

Transparency

The fiber is pulled in alignment with a hand card and cut to a length of 30 m/m. A portion of the fiber weighing 0.04 g was charged in a 20 m/m square glass cell together with anisole. The transmittance of light at a wavelength 562 nm was measured with a spectrophotometer (U-1000, manufactured by Hitachi Limited), and compared with the transmittance of anisole being taken as 100%.

Dyeability

Using a high temperature - high pressure dyeing machine (HUHF212/550 type, manufactured by Nichihan Seisakusho), a tow-like fiber (about 1.5 kg) was dyed under the following conditions, and after drying it by dry heat at 95°C for no shorter than 1 hour, the state of dyeing was evaluarated visually

a) Dye:
b) Temperature: Temperature elevation to 60°C (about 25 minutes) - temperature elavation to 98°C (about 40 minutes) - Retention at 98°C (about 10 minutes) - cooling to 75°C (about 25 minutes) - cooling to 30°C (about 10 minutes).

Stretchability

Degrees of monofilament cutting - winding around a take up roll were evaluated visually.

Spinning Properties

An acrylic fiber was cut to a constant length of 51 m/m and subjected to the steps of worsted spinning - drawing - fine spinning. The state of fly generation in each step was evaluated visually.

Moisture Retention Ratio After Drying

A fiber from a stretching bath was taken in an amount of about 10 g, and the liquid was removed therefrom using a centrifuge (H-100BC type, domestic product) at 3,000 rpm for 2 minutes. Immediately thereafter, its weight X (g) was measured.
Next, after washing with warm water at about 60°C for 2 hours, the fiber was dried by dry heat at 95°C for no less than 1 hour. After cooling it to room temperature its weight X₀ (g) was measured.
The moisture retention ratio was obtained according to the following formula:

Method for Measuring Degree of Crystallization

Both ends of a fiber of 75 mg/75 m/m with the crimp being stretched were fixed on a stand formed with a groove as illustrated in Fig. 3. Using a X ray measurement apparatus (Geiger Flex 2027 type, manufactured by Rigaku Denki), at first an average interference intensity curve at 2Θ = 5 to 40° was obtained by the sample rotation method, which was corrected for air scattering (this area being defined as T). Next, the lowest intensity of interference intensity at each azimuth Ø was measured at 2Θ at which the influence of crystalline interference is the least, and plotted to prepare a noncrystalline interference intensity curve, which was then corrected for air scattering (this area being defined as A). The degree of crystallization was calculated according to the following formula:
${(T-A)/T]X100$
The X ray source was filtered using a Cu anti-cathode and an Ni filter at 40 Kv and 20 mA.

Fastness to Light

An acrylic fiber cut to a constant length of 51 m/m was subjected to 2" (two inch) spinning to obtain a spun yarn of 1/28 count. A circular knitted fabric was obtained using a circular knitting machine of 3 1/2", 16G.
After treating the circular knitted fabric in a carbon arc fadometer (black panel temperature: 63°C) together with a blue scale, the change and deterioration of color of the fabric were judged (JIS L 0842).

EXAMPLE 1

Monomers AN/SAMPS = x/y (weight ratios) of various compositions shown in Table 2 were dissolved in DMF and polymerized using a catalyst, azobisisobutyronitrile (hereafter, abbreviated as "AIBN"), at 68°C X 17 hours. Thereafter, unreacted monomers were removed using an evaporator to obtain various polymer solutions. The compositions and degrees of polymerization of the resulting polymers are shown in Table 2.
The above-described polymer solutions were adjusted to a polymer concentration of 26.5 % by weight to obtain stock spinning solutions, which were respectively extruded through the orifices of a 50,000-hole spinneret having a circular crosssection of a diameter of 0.06 m/m into a coagulation bath DMF/water = 60/40 (weight ratio) at 20°C. After taking them out at a spinning draft of 0.4, they were stretched by 8 times at 85°C.
Subsequently, after washing them with water and pre-oiling, they were dried with a roll at 150°C while shrinking them. Further, post-oiling - crimping - crimping setting (wet heating at 120°C) - post-dry heating were performed to obtain acrylic fibers of 3 d.
The acrylic fibers thus obtained had characteristics shown in Table 2.

EXAMPLE 2

AN/methyl acrylate (hereafter, abbreviated as "MA")/SAMPS = x/y/(100-x-y) (weight ratio) were dissolved in DMF, and polymerized using a catalyst AIBN at 68°C for 17 hours. Thereafter, unreacted monomers were removed therefrom using an evaporator to obtain various polymer solutions. The compositions and degrees of polymerization of the resulting polymers are shown in Table 3. It should be noted that in Exp. No. 9, sodium methallylsulfonate (hereafter, abbreviated as "SAMPS") was used in place of SAMPS.
Subsequently, the same treatment as in Example 1 was repeated to obtain acrylic fibers of 3 d.
The acrylic fibers had characteristics shown in Table 3.

EXAMPLE 3

The polymers having compositions and degrees of polymerization shown in Table 4 were prepared by the DMF solution polymerization method in the same manner as in Example 1. On this occasion, only Exp. No. 1 was prepared by a dimethylsulfoxide (hereafter, abbreviated as "DMSO") solution polymerization method.
The polymers, respectively, were dissolved in DMF to prepare stock spinning solutions having concentrations shown in Table 4. The respective solutions were extruded through the orifices of a 50,000-hole spinneret having a circular crosssection of a diameter of 0.06 m/m into a coagulation bath DMF/water = 60/40 (weight ratio) at 20°C. After taking them out at a spinning draft of 0.4, they were stretched by 8 times at 85°C.
Subsequently, after washing with water, they were shrunk by wet heating at 120°C at a ratio of 10 %. Subsequently, pre-oiling - roll drying (150°C) - post-oiling - crimping - crimp setting (wet heating at 120°C) - post-drying were performed to obtain acrylic fibers of deniers shown in Table 4.
The fibers thus obtained had characteristics shown in Table 4.

EXAMPLE 4

A polymer having the same composition and degree of polymerization as Exp. No. 3 in Example 1 was dissolved in DMF to prepare a stock spinning solution of which the concentration of the polymer was adjusted to 26.5 % by weight. The solution was extruded through the orifices of a 50,000-hole spinneret having a circular crosssection of the diameter shown in Table 5 into a coagulation bath DMF/water = 60/40 (weight ratio) at 20°C. After taking it out at a spinning draft of 0.4, it was stretched by a stretch ratio shown in Table 5 at 85°C in DMF/water = 30/70 (weight ratio).
Subsequently, the same treatment as in Example 3 was repeated to obtain acrylic fibers of 3 d.
The fibers thus obtained had characteristics shown in Table 5.

EXAMPLE 5

A polymer solution having the same composition and degree of polymerization as Exp. No. 3 in Example 1 was dissolved in DMF to prepare a stock spinning solution of which the concentration of the polymer was adjusted to 26.5 % by weight. The solution was extruded through the orifices of a 50,000-hole spinneret having a circular crosssction of a diameter of 0.06 m/m into a coagulation bath DMF/water = 60/40 (weight ratio) at 20°C. After taking it out at the spinning draft shown in Table 6, it was stretched by 8 times at 85°C in DMF/water = 30/70 (weight ratio).
Then, after washing with water, it was shrunk by wet heating at 120°C at the ratios shown in Table 6. On this occasion, only Exp. No. 19 was subjected to the pre-oiling step and steps subsequent thereto immediately after the washing with water. Subsequently, pre-oiling - roll drying (150°C) - post-oiling - crimping - crimp setting (wet heating at 120°C) - post-drying were performed to obtain acrylic fibers of 3 d.
The fibers thus obtained had characteristics shown in Table 6.

EXAMPLE 6

A polymer solution having the same composition and degree of polymerization as Exp. No. 3 in Example 1 was dissolved in DMSO to prepare a stock spinning solution of which the concentration of the polymer was adjusted to 26 % by weight. The solution was extruded through the orifices of a 20,000-hole spinneret having a circular crosssection of a diameter of 0.06 m/m into a coagulation bath DMSO/water = 60/40 (weight ratio) at 22°C. After taking it out at a spinning draft of 0.4, it was stretched by 7 times in hot water at 98°C.
Then, after washing with water, it was shrunk by wet heating at 120°C at a ratio 10 %. Subsequently, pre-oiling - roll drying (150°C) - post-oiling - crimping - crimp setting (wet heating at 120°C) - post-drying were performed to obtain an acrylic fiber of 3 d.
The fiber obtained had a tensile strength of 3.4 g/d, an elongation ratio of 5 %, a shrinkage ratio after dry heat relaxation of 2 %, a shrinkage ratio after wet heat relaxation of 3 %, a tensile elongation of 40 %, a transparency of 88 %, a Young's modulus of 500 kgf/mm², and a fastness to light of class 3 to 4.

EXAMPLE 7

A polymer solution having the same composition and degree of polymerization as Exp. No. 3 in Example 1 was dissolved in dimethylacetamide (hereafter, abbreviated as "DMAc") to prepare a stock spinning solution of which the concentration of the polymer was adjusted to 22 % by weight. The solution was extruded through the orifices of a 20,000-hole spinneret having a circular crosssection of a diameter of 0.08 m/m into a coagulation bath DMAc/water = 55/45 (weight ratio) at 25°C. After taking it out at a spinning draft of 0.5, it was stretched by 9 times in hot water at 98°C.
Subsequently, the same treatment as in Example 6 was repeated to obtain an acrylic fiber of 3 d.
The fiber obtained had a tensile strength of 3.7 g/d, an elongation ratio of 4 %, a shrinkage ratio after dry heat relaxation of 2 %, a shrinkage ratio after wet heat relaxation of 2 %, a tensile elongation of 40 %, a transparency of 89 %, a Young's modulus of 490 kgf/mm², and a fastness to light of class 3 to 4.

EXAMPLE 8

A polymer solution having the same composition and degree of polymerization as Exp. No. 3 in Example 1 was dissolved in 70 % nitric acid to prepare a stock spinning solution of which the concentration of the polymer was adjusted to 16 % by weight. The solution was extruded through the orifices of a 20,000-hole spinneret having a circular crosssection of a diameter of 0.01 m/m into a coagulation bath 35 % nitric acid at 3°C. After taking it out at a spinning draft of 0.5, it was stretched by 9 times in hot water at 98°C.
Then, after washing with water, it was shrunk by wet heating at 120°C at a ratio of 10 %. Subsequently, pre-oiling - roll-drying (115°C) - post-oiling - crimping - crimp setting (wet heating at 120°C) - post-drying were performed to obtain an acrylic fiber of 3 d.
The fiber obtained had a tensile strength of 3.6 g/d, an elongation ratio of 4 %, a shrinkage ratio after dry heat relaxation of 2 %, a shrinkage ratio after wet heat relaxation of 2 %, a tensile elongation of 41 %, a transparency of 93 %, a Young's modulus of 480 kgf/mm², and a fastness to light of class 3 to 4.

EXAMPLE 9

A polymer solution having the same composition and degree of polymerization as Exp. No. 3 in Example 1 was dissolved in sodium thiocyanate/water = 50/50 (weight ratio) to prepare a stock spinning solution of which the concentration of the polymer was adjusted to 12 % by weight. The solution was extruded through the orifices of a 20,000-hole spinneret having a circular crosssection of a diameter of 0.08 m/m into a coagulation bath sodium thiocyanate/water = 50/50 (weight ratio) at -3°C. After taking it out at a spinning draft of 0.3, it was stretched by 9 times in hot water at 98°C.
Subsequently, the same treatment as in Example 8 was repeated to obtain an acrylic fiber of 3 d.
The fiber obtained had a tensile strength of 3.4 g/d, an elongation ratio of 4 %, a shrinkage ratio after dry heat relaxation of 2 %, a shrinkage ratio after wet heat relaxation of 3 %, a tensile elongation of 43 %, a transparency of 97 %, a Young's modulus of 460 kgf/mm², and a fastness to light of class 3 to 4.

EXAMPLE 10

A polymer solution having the same composition and degree of polymerization as Exp. No. 3 in Example 1 was dissolved in zinc chloride/calcium chloride/water = 45/15/40 (weight ratio) to prepare a stock spinning solution of which the concentration of the polymer was adjusted to 10 % by weight. The solution was extruded through the orifices of a 20,000-hole spinneret having a circular crosssection of a diameter of 0.1 m/m into a coagulation bath zinc chloride/water = 45/55 (weight ratio) at 25°C. After taking it out at a spinning draft of 0.3, it was stretched by 9 times in hot water at 98°C.
Subsequently, the same treatment as in Example 8 was repeated to obtain an acrylic fiber of 3 d.
The fiber obtained had a tensile strength of 3.4 g/d, an elongation ratio of 6 %, a shrinkage ratio after dry heat relaxation of 3 %, a shrinkage ratio after wet heat relaxation of 3 %, a tensile elongation of 44 %, a transparency of 87 %, a Young's modulus of 440 kgf/mm², and a fastness to light of class 3 to 4.

EXAMPLE 11

A polymer solution having the same composition and degree of polymerization as Exp. No. 3 in Example 1 was dissolved in DMF to prepare a stock spinning solution of which the concentration of the polymer was adjusted to 30 % by weight. The spinning solution heated to 125°C was extruded through the orifices of a 1,000-hole spinneret having a circular crosssection of a diameter of 0.2 m/m into hot air heated to 125°C and taken out at a rate of 300 m/minute. Monofilament was of 14 deniers.
Then, after stretching by 6 times in hot water at 98°C, washing with water was performed, followed by shrinking by wet heat at 120°C. Subsequently, pre-oiling - roll drying (115°C) - post-oiling - crimping - crimp setting (wet heating at 120°C) - post-drying were performed to obtain an acrylic fiber of 3 d.
The fiber obtained had a tensile strength of 2.9 g/d, an elongation ratio of 6 %, a shrinkage ratio after dry heat relaxation of 3 %, a shrinkage ratio after wet heat relaxation of 3 %, a tensile elongation of 50 %, a transparency of 85 %, a Young's modulus of 410 kgf/mm², and a fastness to light of class 3 to 4.

EXAMPLE l2

A polymer solution having the same composition and degree of polymerization as Exp. No. 3 in Example 1 was dissolved in DMF to prepare a stock spinning solution of which the concentration of the polymer was adjusted to 30 % by weight. The spinning solution was once extruded through the orifices of a 1,000-hole spinneret having a circular crosssection of a diameter of 0.15 m/m into air and then introduced into an coagulation bath DMF/water = 60/40 (weight ratio) at 20°C, and taken out at a spinning draft of 2.2. On this occasion, the distance between the face of the spinnert and the face of the coagulation bath was set to 5 m/m. Subsequently, it was stretched by 9 times in hot water at 98°C.
Thereafter, the same treatment as in Example 6 was repeated.
The fiber obtained had a tensile strength of 3.7 g/d, an elongation ratio of 4 %, a shrinkage ratio after dry heat relaxation of 2 %, a shrinkage ratio after wet heat relaxation of 2 %, a tensile elongation of 37 %, a transparency of 93 %, a Young's modulus of 550 kgf/mm², and a fastness to light of class 3 to 4.

EXAMPLES 13 to 21 and COMPARATIVE EXAMPLES 1 to 6

(1) The acrylic polymers having compositions and degrees of polymerization shown in Table 7 were dissolved, respectively, in dimethylformamide (hereafter, abbreviated as "DMF") to prepare stock spinning solutions of which the concentrations were adjusted, respectively, to 26.5 % by weight. The respective spinning solutions were extruded through the orifices of a 80,000-hole spinneret having a circular cross section of a diameter of 0.055 m/m into a coagulation bath DMF/water = 60/40 (weight ratio) at 20°C. After taking them out at a spinning draft of 0.4, they were stretched in DMF/water = 30/70 (weight ratio) by 8 times at 85°C.
Subsequently, after washing with water and pre-oiling, the fibers were shrunk by wet heating at 150°C at a ratio of 15 %. Subsequently, post-oiling - crimping - crimp setting (wet heating at 120°C) - post-drying were performed to obtain acrylic fibers of 2 d.
The fibers thus obtained had characteristics shown in Table 7. Fig. 4 shows the relationship between the temperature and elongation ratio measured while increasing the temperature in Run 1 (curve (1)), 2 (curve (2)) and 5 (curve (3)).
(2) After cutting the acrylic fibers obtained in Run No. 1 to 5, respectively, to a constant length of 51 mm, 2-inch spun spinning of the fibers was performed to obtain spun yarns of 1/52 count (1/51 count for Examples 19 to 21 and Comparative Examples 5 and 6).
Then, woven fabrics were made with the structure, type of yarn and density shown in Table 8, and the products were subjected in order to the steps of fine spinning, dyeing - reductive washing - soaping, drying, finishing and finish setting to obtain piece-dyed union woven fabrics.

The dyeing was performed in a dye bath which contained a disperse dye (Daianix, produced by Mitsubishi Chemical Industry Co., Ltd.) and a cation dye (Estol, produced by Sumitomo Chemical Co., Ltd.) as a dye, and of which pH was adjusted to about 5 using Sunsalt CI-12 (produced by Nikka Kagaku Co., Ltd.) and Unisalt 5M (produced by Meisei Kagaku Co., Ltd.) as an auxiliary and acetic acid/sodium acetate, with elevating the temperature starting from 60°C to 130°C at a temperature elevation rate of about 1°C/minute, the dyeing being continued at 130°C for 15 minutes. Then, reductive washing was performed at 80°C for 15 minutes in a bath containing hydrosulfite and sodium hydroxide. Soaping was conducted at 70°C for 10 minutes in a bath containing Meisanol L-80 (produced by Meisei Kagaku Co., Ltd.).
Evaluation of the above-described union woven fabrics is shown in Table 9 below.

EXAMPLES 22 to 27 and COMPARATIVE EXAMPLES 7 to 10

(1) The acrylic polymers having compositions and degrees of polymerization shown in Table 10 were dissolved, respectively, in dimethylformamide (hereafter, abbreviated as "DMF") to prepare stock spinning solutions of which the concentrations were adjusted, respectively, to 26.5 % by weight. The respective spinning solutions were extruded through the orifices of a 90,000-hole spinneret having a circular cross section of a diameter of 0.05 m/m into a coagulation bath DMF/water = 60/40 (weight ratio) at 20°C. After taking them out at a spinning draft of 0.4, they were stretched in DMF/water = 30/70 (weight ratio) by 8 times at 850°C.
Subsequently, after washing with water and pre-oiling, the fibers were dried on a roll at 150°C while shrinking at a ratio of 15 %. Subsequently, post-oiling - crimping - crimp setting (wet heating at 120°C) - post-drying were performed to obtain acrylic fibers of 1.5 d.
The fibers thus obtained had characteristics shown in Table 10.
(2) After cutting the acrylic fibers obtained in Run Nos. 6 to 10, respectively, to a constant length of 38 mm, open end spinning of the fibers was performed to obtain spun yarns of 1/18 count (Examples 22 to 24 and Comparative Examples 7 and 8) and 1/26 count (Examples 25 to 27 and Comparative Examples 9 and 10).
Then, woven fabrics were made with the structure and type of yarn shown in Table 11, and the products were subjected in order to the steps of dyeing - reductive washing - soaping, drying, finishing, raising, shearing and finish setting to obtain piece-dyed union woven fabrics.

Dyeing, reductive washing and soaping were performed in the same manner as in Example 13.
Evaluation of the above-described unit knitted fabric is shown in Table 12.

EXAMPLES 28 to 30 and COMPARATIVE EXAMPLES 11 and 12

(1) The acrylic polymers having compositions and degrees of polymerization shown in Table 13 were dissolved, respectively, in dimethylformamide (hereafter, abbreviated as "DMF") to prepare stock spinning solutions of which the concentrations were adjusted, respectively, to 26.5 % by weight. The respective spinning solutions were extruded through the orifices of a 10,000-hole spinneret having a circular cross section of a diameter of 0.11 m/m into a coagulation bath DMF/water = 60/40 (weight ratio) at 20°C. After taking them out at a spinning draft of 0.4, they were stretched in DMF/water = 30/70 (weight ratio) by 8 times at 85°C.
Subsequently, after washing with water and pre-oiling, the fibers were dried on a roll at 150°C while shrinking at a ratio of 15 %. Subsequently, post-oiling - crimping - crimp setting (wet heating at 120°C) - post-drying were performed to obtain acrylic fiber whose single yarns are of 10 d.
After dyeing the above-described fibers cut to a constant length of 152 mm in brown (deep color) as shown in Table 1, the fibers were subjected to semi-worsted spinning to obtain 1/6 count spun yarns. Then, the yarns were applied on a base cloth made of polypropylene fiber (yarn density: weft 22/inch, warp: 15/inch) by tufting (with pile, 350 g/m²), and a latex (polymer component: 12 % by weight, calcium carbonate: 35 % by weight, antioxidant: 1 % by weight) having a solid content of 48 % by weight was coated in a thickness of 600 g/m² on the back surface of the resulting fabric base, and dried at 140°C for 15 minutes.
The acrylic fibers and surface materials for electric heating carpets had characteristics shown in Table 13.

EXAMPLES 31 to 33 and COMPARATIVE EXAMPLES 13 and 14

(1) The acrylic polymers having composition and degrees of polymerization shown in Table 14 were dissolved, respectively, in dimethylformamide (hereafter, abbreviated as "DMF") to prepare stock spinning solutions of which the concentrations were adjusted, respectively, to 26.5 % by weight. The respective spinning solutions wer extruded through the orifices of a 50,000-hole spinneret hving a circular cross section of a diameter of 0.06 m/m into a coagulation bath DMF/water = 60/40 (weight ratio) at 20°C. After taking them out at a spinning draft of 0.4, they were stretched in DMF/water = 30/70 (weight ratio) by 8 times at 85°C.
Subsequently, after washing with water and pre-oiling, the fibers were dried on a roll at 150°C while shrinking at a ratio of 15 %. Subsequently, post-oiling - crimping - crimp setting (wet heating at 120°C) - post-drying were performed to obtain acrylic fiber whose single yarns are of 10 d.
After dyeing the above-described fibers cut to a constant length of 76 mm in brown (deep color) as shown in Table 1, the fibers were subjected to woolen spinning to obtain 1/5 count spun yarns.
Double weave woven fabrics (density: weft; 18/inch, warp; 32/inch) were made using the above-described acrylic fibers as a warp and a polyester spun yarn (1/20 count) as a weft. By performing raising 5 times and shearing 2 times, fabric bases for electric heating blankets were obtained.
The acrylic fibers and fabric bases for electric heating blankets had characteristics shown in Table 14.

EXAMPLE 34

A yellow pigment (Hoechst Green GG01) pulverized to an average particle diameter of about 1 µm was dispersed in dimethylformamide (hereafter, abbreviated as "DMF").
The acrylic polyers having compositions and degrees of polymerization shown in Table 15 were dissolved, respectively, in DMF, and the resulting solutions were added to the dispersion for mixing to prepare stock spinning solutions in which the concentrations of the polymer were adjusted, respectively, to 25 % by weight and the concentration of the pigment were adjusted to 2 % by weight/polymer.
The respective spinning solutions were extruded through the orifices of a 80,000-hole spinneret having a circular cross section of a diameter of 0.055 m/m into a coagulation bath DMF/water = 60/40 (weight ratio) at 20°C. After taking them out at a spinning draft of 0.4, they were stretched in DMF/water = 30/70 (weight ratio) by 8 times at 85°C.
Subsequently, after washing with water and pre-oiling, the fibers were dried on a roll at 150°C while shrinking at a ratio of 15 %. Subsequently, post-oiling - crimping - crimp setting (wet heating at 120°C) - post-drying were performed to obtain acrylic fiber of 2 d.
The acrylic fibers thus obtained had characteristics shown in Table 15.

EXAMPLE 35

The acrylic fiber in Run No. 1 was cut to a constant length of 51 m/m and 2" weave spinning was carried out to obtain a yarn of 2/34 count. Then, using teh thus-obtained spun yarn, there was obtained a plain weave fabric having a density of warp: 73/inch and weft: 73/inch.
The above-described woven fabric was dipped in a processing bath composed of 5 parts by weight of Asahi Guard AG-710 (fluorine resin based waterproofing agent, produced by Asahi Glass Co., Ltd.), 1 part by weight of High Softer K-10 (produced by Meisei Kagaku Co., Ltd.), 2 parts by weight of isopropanol and 92 parts by weight of water, followed by pressing at a pressing ratio of 50 %, drying at 100°C and heating at 150°C.
The above-described woven fabric was dipped in a processing bath composed of 20 parts by weight of Boron Coat (silicone resin based waterproofing agent, produced by Shin-estu Kagaku Co., Ltd.) and 80 parts by weight of trichloroethylene, and then pressed at a pressing ratio of 40 %, followed by drying at 100°C and heating at 160°C.
The waterproof cloth thus obtained had a water repellency of 100 (the spray method according to JIS L1092), water resistance of 25.8 cm (JIS L1098 method (low water pressure method)), fastness to light of class 4 or more (the third light exposure method according to JIS L0842), elongation after dry heating at 140°C of 1 % longitudinally and of 0 % transversely. The elongation after dry heating at 140°C was measured by the following method. That is, the upper end of the waterproof cloth cut to a width of 50 mm and a length of 150 mm was clamped with a clip with a clamping width of 50 mm with its upper end fixed on a stand. Then, the lower end of the water proof cloth was clamped with a separate clip having a clamping width of 50 mm and being attached thereon a weight weighing 50 g together with the weight of the clip itself. Further, the waterproof cloth was provided with marks so that their distance was 100 mm. The waterproof cloth thus suspended on the stand was treated by dry heating at 140°C for 24 hours. After cooling to room temperature, the distance between the marks A (mm) was measured. The elongation was calculated according to formula: $((A - 100)/100)X100$
.

Claims

An acrylic fiber characterized by
(A) comprising an acrylonitrile copolymer
(a) being composed substantially of a polymerizable unit represented by the following formula (1)
and a polymerizable unit represented by the following formula (2)
wherein M is a hydrogen atom or a monoequivalent cation,

(b) the polymerizable unit (2) occupying from 0.4 to 1.5 mole % based on the sum of the polymerizable units (1) and (2),

(c) the acrylonitrile copolymer having a degree of polymerization in a range of from 600 to 1,500,

(B) the acrylic fiber having a tensile strength in a range of from 2 to 5 g/d, and

(C) the acrylic fiber having an elongation of no higher than 10% at 260°C with respect to a relationship between a temperature and an elongation while increasing the temperature.
An acrylic fiber characterized by
(A') comprising an acrylonitrile copolymer
(a') being composed substantially of the polymerizable unit represented by the above-described formula (1), the polymerizable unit represented by the above-described formula (2), and a polymerizable unit represented by the formula (3) derived from a monomer copolymerizable with acrylonitrile other than the polymerizable unit represented by the formula (2),

(b') the polymerizable unit (2) occupying from 0.4 to 1.5 mole % based on the sum of the polymerizable units (1) and (2), and the polymerizable unit (3) occupying no more than 5 % by weight based on the polymerized polymer (1),

(c) the acrylonitrile copolymer having a degree of polymerization in a range of from 600 to 1,500,

(B) the acrylic fiber hving a tensile strength in a range of from 2 to 5 g/d, and

(C) the acrylic fiber having an elongation of no higher than 10% at 260°C with respect to a relationship between a temperature and an elongation while increasing the temperature.
The acrylic fiber as claimed in Claims 1 or 2, wherein said acrylic fiber is crimped.
The acrylic fiber as claimed in Claim 1 or 2, wherein said acrylic fiber has a shrinkage ratio after dry heat relaxation at 210°C of smaller than 3 %.
The acrylic fiber as claimed in Claim 1 or 2, wherein said acrylic fiber has a shrinkage ratio after wet heat relaxation at 130°C of smaller than 3 %.
The acrylic fiber as claimed in Claim 1 or 2, wherein said acrylic fiber has elongation in a range of from 35 to 60 %.
The acrylic fiber as claimed in Claim 1 or 2, wherein said acrylic fiber has a transparency of at least 80 %.
The acrylic fiber as claimed in Claim 1 or 2, wherein said acrylic fiber has a Young's modulus in a range of from 400 to 700 kg/mm².
The acrylic fiber as claimed in Claim 1 or 2, wherein said acrylic fiber has fastness to heat (120°C X 48 hours) of at least class 3.
The acrylic fiber as claimed in Claim 1 or 2, wherein said acrylic fiber has a degree of crystallizationin a range of from 20 to 40 %.
The acrylic fiber as claimed in Claim 2, wherein said polymerizable unit (3) is one represented by formula (3) below
wherein R is a hydrogen atom or a methyl group; and Y is a group selected from the class consisting of a group of formula -COOX (where X is a hydrogen atom, a sodium atom or a methyl group), -OCOCH₃, -CONH₂, -C₆H₅, -CH₂SO₃Na and -C₆H₄SO₃Na.
A methof for producing an acrylic fiber, characterized by:
(1) extruding a stock spinning solution of the acrylonitrile copolymer identified by (A) or (A') above through orifices of a spinneret to form fine streams of the stock spinning solution;

(2) stretching the fine streams by from 5 to 10 times while coagulating them to form spun filaments;

(3) heating the spun filaments to shrink them at a ratio of 3 to 25%; and

(4) subjecting the resulting shrunk filaments to a drying step.
A union knitted or woven fabric including an acrylic fiber and an aromatic polyester fiber, characterized by containing the acrylic fiber defined in Claim 1.
The union knitted or woven fabric as claimed in Claim 13, wherein said aromatic polyester fiber is composed of an aromatic polyester which is a homo- or co-polyester of ethylene terephthalate including ethylene terephthalate as a main repeating unit.
A union knitted or woven fabric, characterized by containing the acrylic fiber defined in Claim 2.
The union knitted or woven fabric as claimed in Claim 15, wherein said aromatic polyester fiber is composed of an aromatic polyester which is a homo- or co-polyester of ethylene terephthalate including ethylene terephthalate as a main repeating unit.
A surface material for electric heating carpets, characterized by containing the acrylic fiber defined in Claim 1.
The surface material for electric heating carpets, characterized by containing the acrylic fiber defined in Claim 2.
An electric heating carpet comprising the surface material defined in Claim 17.
An electric heating carpet comprising the surface material defined in Claim 18.
A fabric base for electric heating blankets, characterized by containing the acrylic fiber defined in Claim 1.
A fabric base for electric heating blankets, characterized by containing the acrylic fiber defined in Claim 2.
An electric heating blanket comprising the fabric base defined in Claim 21.
An electric heating blanket comprising the fabric base defined in Claim 22.
A waterproof cloth, characterized by having as a base cloth a cloth composed of the acrylic fiber defined in Claim 1.
A waterproof cloth, characterized by having as a base cloth a cloth composed of the acrylic fiber defined in Claim 2.
The waterproof cloth as claimed in Claims 25 or 26, wherein said acrylic fiber is mass-colored.
A cloth composed of the acrylic fiber defined in Claim 25 as a base cloth for the waterproof cloth defined in Claim 25.
A cloth composed of the acrylic fiber defined in Claim 25 as a base cloth for the waterproof cloth defined in Claim 26.