JPH0129888B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a flame-retardant acrylic synthetic fiber with good underwater splitting properties and heat resistance. Generally, when using acrylic synthetic fibers to produce paper, nonwoven fabrics, and similar products, the first difficulty that arises is that the short fibers do not separate in water, for example, even after the beating process. Because the fibers are not divided, they remain in a rod-like form, resulting in the formation of paper products.
Even with the strength of the paper, I have not been able to obtain anything satisfactory. In addition, heat resistance of acrylic synthetic fibers is required when used for mixed papers of acrylic synthetic fibers and pulp, or for roofing materials in which nonwoven fabrics made from acrylic synthetic fibers are impregnated and coated with heated and melted asphalt. . Generally, it is said that a linear shrinkage rate of 10% or less under dry heat at 160°C is the heat resistance desired for acrylic synthetic fibers in these fields that require heat resistance. Normally, when acrylic synthetic fibers are obtained by wet spinning, they are spun, stretched, washed, and dried. Therefore, neither fiber-to-fiber adhesion nor fusion occurred. That is, if the fibers up to this point are used, the number of micropoid particles will be extremely large, but the fiber splitting properties in water will be extremely good. However, when entering the decreasing rate drying period of the drying process, the fibers change from a so-called water-swollen gel state to densification by burning, and most of the microvoids disappear, as well as adhesion and fusion between fibers, resulting in poor fiber separation until the final product. It remains as a thread. In order to prevent this fiber-to-fiber adhesion and fusion, an oil agent is usually applied after the water washing process and the drying process is performed, but the splitting properties up to the fiber grade required for spinning are improved, but the underwater splitting properties of papermaking grade are improved. It has not yet been possible to obtain good fibers. In addition, the fibers after the drying process shrink by about 20% or more at dry heat of 160℃, so it is necessary to add a shrinking process to improve the heat resistance. -The degree of adhesion and fusion between fibers deteriorates significantly, making them increasingly unsuitable for papermaking.Acrylic synthetic fibers are usually used in fields that require heat resistance, such as asphalt torfing materials. The reality is that it has not been done. In order to improve the underwater splitting properties of such acrylic synthetic fibers, Japanese Patent Publication No. 39-197 and Japanese Patent Publication No.
Publication No. 51-28728 and other publications propose using the water-swollen gel-like product after spinning, stretching, and washing with water, but although the fiber splitting properties in water are sufficient, in both cases the cutting point at the time of cutting is fused. Easy to wear,
Not only do they have disadvantages such as poor dispersibility in water, in which the air contained in the microvoids cannot escape completely and the fibers float to the top of the water surface, and paper forming strength is reduced, but they also lack heat resistance, e.g. With the drying of
Its uses are limited as it shrinks by more than 20%. That is, it can be said that an acrylic synthetic fiber with sufficiently good splitting properties in water and good heat resistance has not yet been obtained. The present inventors completed the present invention as a result of intensive research to eliminate the defects of the conventional technology. An object of the present invention is to provide a flame-retardant acrylic synthetic fiber with good splitting ability in water and heat resistance, and a method for producing it industrially easily and inexpensively. The method of the present invention comprises at least 40% by weight of acrylonitrile, 20-60% by weight of vinylidene chloride or an acrylic polymer mixture, and 0.5-5 parts by weight of antimony and aluminum based on 100% by weight of said copolymer or said mixture. A spinning dope containing at least one metal compound selected from the group consisting of tin and zinc is wet-spun, stretched, washed with water and strain-dried, and then the water content is 10 to 200% by weight based on the weight of the fiber.
It is characterized in that it is applied and then subjected to tension heat treatment with moist heat at 100 to 140°C. The acrylic copolymer applicable to the present invention contains at least 40% by weight of acrylonitrile and 20 to 60% by weight of acrylonitrile.
It contains vinylidene chloride or vinyl chloride, and also includes those copolymerized with 20% by weight or less of copolymerizable monomers. Examples of these copolymerizable monomers include acrylic esters such as methyl acrylate, methyl methacrylate, and ethyl acrylate, or alkyl esters of methacrylic acid, amides such as acrylamide and methacrylamide, and N-monosubstituted thereof. Examples include N, N-disubstituted amides, vinyl acetate, or monomers containing sulfonic acid groups such as styrene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, 2-acrylamide, 2-methylpropanesulfonic acid, and salts thereof. It will be done. When 0.3 to 1.2% by weight of a monomer containing a sulfonic acid group is copolymerized, dense fibers can be obtained by suppressing the generation of countless minute voids. Acrylic polymer mixture is a mixture of two or more types of acrylic copolymers, and this mixture contains at least 40% by weight of copolymerized acrylonitrile and 20 to 60% by weight of vinylidene chloride or vinyl chloride. It contains. Usually, vinylidene chloride or two types of acrylic copolymers having different vinyl chloride contents are mixed. For these acrylic copolymer mixtures, acrylic copolymers obtained by copolymerizing the above copolymerizable monomers such as methyl acrylate and allylsulfonic acid may also be used. When these acrylic copolymer mixtures contain 0.5 to 3% by weight of copolymerized anionic monomers, void generation can be prevented and dyeability can be improved. Further, the acrylic polymer mixture of the present invention can contain cellulose acetate in an amount of 2 to 30% by weight based on the total amount of the polymer. When cellulose acetate is mixed with an acrylic polymer or a polymer mixture in a dimethylformamide solvent, for example, the acrylic polymer becomes a sea and the cellulose acetate becomes an island. A porous acrylic synthetic fiber in which cellulose is dispersed in a striped manner in the fiber axis direction is obtained. Since the resulting fibers are porous, their apparent specific gravity is reduced to the true ratio of acrylic synthetic fibers divided by (1+V), where the porosity is V, and the amount of fiber used can be reduced by that amount. Because it is a porous fiber with a large pore structure, water immediately penetrates into the fiber by capillary action, and like hydrophilic fibers, it has particularly good dispersibility in water (the property of dispersing in water with a difference in fibrillation in water). If the amount of vinylidene chloride or vinyl chloride in the acrylic copolymer or acrylic polymer mixture applied to the present invention exceeds 60% by weight and the amount of acrylonitrile is less than 40% by weight, yarn quality such as strength and elongation may deteriorate. Along with this decrease, the heat resistance and whiteness of the fiber also decrease. On the other hand, the amount of vinylidene chloride or vinyl chloride
If it is less than 20% by weight, the flame retardancy will be reduced and should be avoided. Antimony, aluminum applied to the present invention,
At least one selected from the group consisting of tin and zinc
Species of metal compounds include metal oxides such as antimony trioxide, antimony pentoxide, alumina, tin oxide, zinc oxide, and zinc borate, metastannic acid, etc. Antimony trioxide, antimony pentoxide, zinc borate and metastannic acid are preferred. These metal compounds are used in an amount of 0.5 to 5 parts by weight, preferably 1 to 3 parts by weight, per 100 parts by weight of the acrylic copolymer or acrylic polymer mixture. If the amount of these metal compounds is less than 0.5 parts by weight, the flame retardancy will be insufficient, while if it exceeds 5 parts by weight, not only will the quality of the yarn deteriorate, but also the workability such as hyper-strengthening and spinning drawability will decrease. do. The metal compound can be dispersed in the spinning dope in advance, or can be rapidly kneaded immediately before spinning. Solvents for the spinning dope and spinning bath (coagulation bath) of the present invention include organic solvents such as dimethyl sulfoxide, dimethyl formamide, and dimethyl acetamide, as well as inorganic solvents such as concentrated nitric acid, zinc chloride aqueous solution, and rhodan soda aqueous solution. Not limited. Further, water may be added to the spinning dope in an amount that does not cause the spinning dope to gel. For spinning, an aqueous solution of the above-mentioned organic solvent or an organic solvent such as isopropyl alcohol, methyl alcohol, kerosene, etc. can be used as a coagulation bath, or the above-mentioned inorganic solvent can also be used, but in particular, an aqueous solution of the solvent used as the solvent for the polymer is preferable because it is economical from the point of view of solvent recovery.
Further, organic solvents such as dimethylformamide, dimethylsulfoxide, and dimethylacetamide are preferred from the viewpoint of economical solvent recovery and ease of handling. However, compared to inorganic solvents, it is difficult to densify the fibers during the spinning process. Therefore, in order to complete the burning out of voids during the drying process, drying is performed under more intense conditions, which prevents adhesion and fusion between fibers. It's easy to get angry. However, even when an organic solvent is used, even if the temperature of the spinning bath is set to 15°C or lower and drying is performed under more intense conditions, fiber-to-fiber agglutination,
The fusion is considerably relaxed, and by adding water after the drying step, the fibers are completely separated from each other and fibers with good water content are obtained, which is preferable. When an organic solvent aqueous solution is used as a spinning bath,
If the temperature of the spinning bath exceeds 15°C, the fiber splitting property in water becomes progressively poorer, which is not preferable. Spinning may be carried out under the same conditions as for ordinary acrylic synthetic fibers. That is, the film is sequentially stretched through several stages of bathtubs and then washed with water. After that, an oil agent is usually applied for the purpose of preventing sticking and static electricity problems in the next drying process, but since most of it penetrates into the fibers, it is only necessary to apply the minimum necessary amount to avoid problems in the drying process. In the next drying process, tension drying is performed in the same way as normal acrylic fibers to reduce the moisture content to 2% by weight.
It is preferable to do the following. In the drying process, the fibers are in a water-swollen gel-like state until the transition from the constant-rate drying period to the decreasing-rate drying period, but once the waning-rate drying period begins, the fibers change from the so-called water-swelling gel-like state to densification as microvoids are removed by burning. be done. However, if the moisture content exceeds 2% by weight, microvoids remain in the fibers, which is not preferable. It is an essential condition of the present invention that 10 to 200% by weight of water be added to the fibers after the drying process. Water can be applied to the fibers by sprinkling it on the fibers using a shower method, or by immersing the fibers in a bathtub. Further, even if the water contains oil, there is no problem whatever the temperature of the water. In other words, if 10 to 200% by weight of water is added to the dried fibers, most of the adhesion and fusion between the fibers produced in the drying process will disappear, and fibers with good splitting properties in water can be obtained. That is surprising. In addition, if water is not added to the fibers after drying, the adhesion and fusion between the fibers formed in the drying process will become even stronger in the next moist heat treatment process, resulting in only fibers with extremely poor splitting properties in water. However, if water is added to the fibers after drying, fibers with sufficiently good splitting properties in water can be obtained without causing fiber-to-fiber adhesion or fusion even in the subsequent moist heat treatment step. Therefore, it is best to apply water to the fibers after drying. The amount of water applied to the fiber after drying is preferably 10 to 200% by weight; if it is less than 10% by weight, the splitting effect will not be sufficient, and if it exceeds 200% by weight, the splitting effect will reach saturation. This is inappropriate as the subsequent steps will be flooded with water. The preferred amount of water is 50-150% by weight
It is. Next, it is an essential condition of the present invention that the fibers to which water has been applied after drying are subjected to emergency heat treatment with moist heat at 100 to 140°C. Although it varies slightly depending on the stretching rate during spinning, acrylic synthetic fibers after the drying process typically shrink by 20 to 30% when dry heated at 160°C, but when heated with wet heat at 100° to 140°C. If the fiber is sufficiently shrunk or after being stretched, a fiber with good heat resistance that eliminates latent shrinkage force can be obtained. If the moist heat is less than 100℃, it will not shrink sufficiently, and
When the temperature exceeds 140°C, not only the shrinkage effect reaches saturation but also it is not economical. Further, it is necessary that the heat treatment is a tension heat treatment. During heat treatment, if the fibers are in a relaxed or overlapping state, fine wrinkles will form on the fiber surface. These wrinkles are undesirable because they impair fiber-to-fiber dispersion, so-called water dispersibility, during paper making. The preferred tension heat treatment is 10-30% between rollers
It is to contract. The acrylic synthetic fiber thus obtained is dried by dry heat.
It shrinks by less than 10% at 160°C, and has properties suitable for paper making with good fiber splitting properties in water. The present invention will be explained in detail below with reference to Examples.
Note that parts and percentages used in the examples represent parts by weight and percentages by weight. In addition, the ability to split fibers in water is determined by placing 0.2 g of acrylic synthetic fiber cut at 5 m/m into a beaker containing 500 c.c. of water, thoroughly stirring with a glass rod, and observing with the naked eye. That is, the evaluation method is such that a state in which there are no fiber-to-fiber adhesion or fused rod-like objects is grade 5, and as the number of rod-like objects increases by 10, the grade decreases by one grade. Therefore, 1st grade refers to the state in which there are 40 or more. In addition, the water dispersibility was 0.2 m/m.
Put g of acrylic synthetic fiber into a beaker containing 500 c.c. of water, stir thoroughly with a glass rod, and leave for 5 minutes. After standing, uniform dispersion over the entire surface of the beaker was graded 5, and agglomeration at the top or bottom was grade 1, and the grades in between were graded 5. The flame retardancy test was conducted using the JIS L-1092 A-1 method, and the heat resistance test was conducted by measuring the shrinkage rate in 30 minutes at 160℃ dry heat, and if it was 10% or less, it passed (〇) 10
If it was larger than %, it was judged as a failure (×). Example 1 Acrylonitrile (hereinafter abbreviated as AN): Vinylidene chloride: Sodium allylsulfonate = 57:
Dimethylformamide (hereinafter abbreviated as DMF), an acrylic copolymer with a composition of 41:2 (%)
Blend 2.5% antimony trioxide to the acrylic copolymer in the solution to adjust the acrylic copolymer concentration.
A 24.5% spinning stock solution was obtained. The stock solution was mixed with DMF: water =
55:45 (%) Spun using a 0.06 mm diameter spinneret during coagulation and melting at 15°C, first stretched 5 times after spinning, washed with water, coated with oil, and heated in a hot roller dryer at 130°C for the first time. Dry (primary) as shown in the table, apply water at different moisture percentages according to the method shown in Table 1, and heat with moist heat at 105℃.
Stretched 1.5 times and shrunk 0.8 times with moist heat at 130℃ for 1.5d.
A fiber in a no-crimp tow state was obtained. This was dried and cut into pieces of 5 m/m using a guillotine cutter to measure fiber splitting properties in water, and cut into pieces of 2 m/m to measure dispersibility in water.

[Table] Kunakatsuta.
Example 2 AN: Vinyl chloride: Sodium allylsulfonate =
2 parts of 60:30:10 (%) acrylic copolymer,
AN: Vinyl chloride: Sodium allylsulfonate =
22 parts of a 42:57:1 (%) acrylic copolymer and the metal compounds shown in Table 2 were dissolved and mixed in 80 parts of DMF to obtain a spinning stock solution. The spinning stock solution was spun using a 0.06 m/mφ spinneret in a coagulation solution of DMF: water = 60:40 (%) at 10°C, and after spinning, the first stretching was performed 6 times, and after washing with water, an oil agent was attached.
After drying in a heated roller dryer at 130℃ to a moisture content of 0.5%, 100% water was applied at 30℃ using an immersion method, and then the product was shrunk by 0.85 times with moist heat at 130℃ for 2 d.
A fiber in a no-crimp tow state was obtained. This was dried, cut into pieces of 0.7 m/m using a guillotine cutter, and subjected to flock processing to obtain ^a curtain with a weight of 350 g/m. This was subjected to a combustion test using the JIS L-1091 A-1 method (45° micro burner method).

[Table] Example 3 AN: Antimony trioxide was added to the acrylic copolymer in a dimethyl sulfoxide solution of an acrylic copolymer with a composition of vinylidene chloride: sodium methallyl sulfonate = 55:43:2 (%). A spinning stock solution having an acrylic copolymer concentration of 23.5% was obtained by blending 2%. The stock solution was dimethyl sulfoxide:water=
55:45 (%) Spun using a 0.065 m/mφ spinneret during coagulation and melting at 25°C, and after spinning, primary stretching was performed 6 times,
After washing with water, apply the oil and dry in a heated roller dryer at 130°C until the moisture content reaches 0.5%. Apply 80% water at 30°C, then apply tension heat treatment at different temperatures as shown in Table 3. , a 2d non-crimped tow fiber was obtained. This was dried and cut into 5 m/m pieces using a guillotine cutter to measure fiber splitting ability in water, and the shrinkage rate at 160° C. in dry heat.

【table】

Claims (1)

[Claims] 1. At least 40% by weight of acrylonitrile and 20% by weight of acrylonitrile.
An acrylic copolymer or acrylic polymer mixture containing ~60% by weight of vinylidene chloride or vinyl chloride, and 0.5 to 5 parts by weight of antimony, aluminum, tin and A spinning dope containing at least one metal compound selected from the group consisting of zinc is wet-spun, stretched, washed with water, strain-dried, and then added with 10 to 200% water by weight based on the weight of the fiber.
A method for producing a flame-retardant acrylic synthetic fiber with good splitting properties in water and good heat resistance, the method comprising carrying out tension heat treatment with moist heat at 100 to 140°C. 2. The method according to claim 1, wherein the acrylic copolymer contains 0.5 to 3% by weight of anionic monomer. 3. The method according to claim 1, wherein the acrylic polymer mixture is a mixture of two types of acrylic copolymers having different contents of vinylidene chloride or vinyl chloride. 4 0.5 to 3% by weight of acrylic copolymer mixture
2. The method of claim 1, comprising a polymerized anionic monomer. 5. The method according to claim 1, wherein the acrylic polymer mixture contains 2 to 30% by weight of cellulose acetate based on the total amount of the polymer. 6. The method according to claim 1, wherein the metal compound is blended in an amount of 1 to 3 parts by weight. 7. The method according to claim 1, wherein the solvent for wet spinning is an organic solvent such as dimethylformamide, dimethylsulfoxide, dimethylacetamide, etc., and the temperature of the aqueous solution of the organic solvent in the spinning bath is 15° C. or lower. 8. The method according to claim 1, wherein the moisture content of the strain-dried fibers is 2% by weight or less. 9 The moisture content of the fibers to which water has been applied after tension drying is 50~
150% by weight. 10. The method according to claim 1, wherein the tension heat treatment provides a shrinkage of 10 to 30%.