JPS6262909A - Production of acrylonitrile based fiber - Google Patents

Abstract

PURPOSE:To remarkably increase the spinning speed and obtain the titled fibers, by copolymerizing acrylonitrile with another polymerizable monomer in the presence of a specific emulsifying agent to form a copolymer having a specific reduced viscosity, heat-treating the copolymer to evaporate and remove the emulsifying agent and melt spinning the resultant copolymer. CONSTITUTION:40-95wt% acrylonitrile is emulsion copolymerized with 5-60wt% another copolymerizable monomer, e.g. methyl acrylate, in the presence of an emusifying agent normally evaporating at a temperature above the melting temperature of the resultant copolymer, particularly >=180 deg.C, e.g. dioctyl sodium sulfosuccinate, to give a copolymer having 0.2-1.0 reduced viscosity, which is then washed with water, dehydrated and heat-treated, preferably under reduced pressure at a temperature above the melting temperature of the above-mentioned copolymer to evaporate the emulsifying agent and reduce the amount of the residual emulsifying agent to preferably <=1,000ppm. The resultant copolymer is then melt spun under conditions of, e.g. 150-250 deg.C at 800-5,000m/min spinning speed to afford the aimed fibers.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to acrylonitrile fiber t used for clothing or as a precursor for carbon fibers, and a method for producing it by a melt spinning method.

[Conventional technology]

Unlike thermoplastic polymers such as polyamide and polyester, acrylonitrile-based polymers undergo a cyclization reaction of the nitrile group when heat-treated, making them infusible, making it difficult to form fibers using melt-spinning methods. A friend who has been considered a friend. Conventional methods for producing this Tomome acrylonitrile fiber include ef-dimethylformamide, dimethylacetamide,
A wet spinning method and a dry spinning method are employed in which the entire spinning stock solution is a solution of dimethyl sulfoxide, γ-butyrolactone, a rhodan salt aqueous solution, or polyacrylonitrile dissolved in a good solvent such as Nitrate #1. However, in these fiber manufacturing methods using these spinning methods, it is essential to completely remove the solvent from the system during the spinning process, and the spinning speed is limited to a maximum of 300 m/min. 1. Spinning speed 100 for polyamide fibers and polyester fibers that are completely melt-spun.
0? This is extremely slow compared to FI/min or higher, and is one of the reasons for poor physiological performance.

In this difficult current situation, acrylonitrile polymer tm
Studies are also underway on methods of producing fibers by melt-spinning, such as those disclosed in Japanese Patent Publication No. 55-501061, Japanese Patent Publication No. 47723-1982, and Japanese Patent Publication No. 59-13m515.
A spinning method for an acrylonitrile polymer as disclosed in the above publication has not yet been developed. In both of these methods, as little water as possible is coordinated with the acrylonitrile yarn polymer, water is used as a plasticizer, and the material is discharged from a spinning nozzle under heating and pressure to form fibers. However, even if the heating and pressurizing conditions in the pressurizing zone and humidity control conditions are strictly regulated, it is not possible to prevent the formation of voids due to water volatilization in the extruded fibrous acrylonitrile polymer molded product. A technology has not yet been developed to produce fibers that are produced by dry spinning or wet spinning and have no color loss compared to leather fibers.

- Has a technology been developed to make a gas barrier film by melting an acrylonitrile polymer in a full bath and forming it into a film?
% and the fiber diameter is less than 20μ)
It is completely impossible to fully apply film forming technology to the production of IJJ fibers.

[The problem that the invention attempts to solve]

In view of the current state of the manufacturing method of acrylonitrile fibers using the melt-spinning method as described above, the Ministry of the Invention has earnestly studied the method of manufacturing acrylic fibers using the melt-spinning method that does not use any plasticizers such as water. As a result, the present invention was completed.

[Elaborate means to solve all problems]

The gist of the present invention is that acrylonitrile 40-9
5% by weight and 5 to 60% by weight of another copolymerizable unsaturated monomer at a temperature higher than the bath melting temperature of the polymer to conduct emulsion polymerization in the presence of an emulsifier that evaporates. The entire Acrylic IJQ nitrile yarn polymer with a reduced viscosity of 02 to 10 is heated at a temperature higher than the bath melting temperature of the polymer, and then evaporated with an emulsifier contained in the acrylonitrile polymer.
The purpose is to produce acrylonitrile fibers by melt spinning at a temperature higher than the melting temperature of the polymer.

It is necessary that acrylonitrile be copolymerized in the acrylonitrile polymer used in the present invention in a proportion of 40 to 95% by weight. If the copolymerization component in the polymer is less than 40% by weight, it is impossible to produce noise with excellent fiber performance. Other copolymerizable unsaturated monomers that can be copolymerized with acrylonitrile include acrylic acids and methacrylic acids such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, methyl acrylate, ethyl acrylate, butyl methacrylate, and propyl acrylate. esters, vinyl chloride, vinyl bromide, vinylidene chloride, etc., vinyl rhodanides, acids such as methacrylic acid, acrylic acid, itaconic acid, crotonic acid, vinyl sulfonic acid, etc., or maleic acid. acid imide, phenylmaleimide,
Acrylamide, methacrylamide, styrene, α-methylstyrene, etc. can be mentioned.

The reduced viscosity of the acrylonitrile polymer used in carrying out the present invention is
When dissolved in dimethylformamide 100- and measured at 25°C, it was 9 (ηs plo ), and in the present invention, c
It is necessary to be in the range of L2 to 1.0. When the polymer viscosity is less than α2, not only the bath melting property is not good, but also the strength and knot strength of the obtained fibers are not sufficient, and the utility value as a fiber is small. On the other hand, if the reduced viscosity exceeds 1.0, the melt spinning process will be poor and undesirable.

Polymers with reduced viscosity in the range of CL2 to 1.0 are 160 to 2.
When heated to 50°C, it can be easily bath-melted without a plasticizer such as water, and can be made into fibers without causing an undesirable cyclization reaction, and the resulting fibers have a strength of 2 to 10'//d. , and an elongation of 10 to 40 inches.

The acrylonitrile polymer of the present invention having a reduced viscosity of α2 to 1.0 can be obtained by ordinary emulsion polymerization, and various emulsifiers such as nonionic, anionic, and cationic threads can be used. However, when the obtained acrylonitrile polymer is melt-spun at a temperature of 160°C or higher, especially in the temperature range of 200 to 250°C, the emulsifier remaining in the polymer evaporates or thermally decomposes and foams easily, resulting in poor melt-spinning stability. Not only is the physical property of the obtained fiber reduced,
The chemical properties are deteriorated, and the aesthetic appearance of Kyotomo Fl&W is spoiled, which is undesirable. Therefore, the emulsifier used in the present invention is
It is necessary to select all emulsifiers that evaporate by heat treatment at a temperature higher than the melting temperature of the polymer used, particularly at a temperature higher than 180°C.

Specifically, anionic surfactants such as N-amyl amino acids, dialkyl sulfosuccinates, alkyl phosphates, alkylbenzenesulfone rR salts, nonionic surfactants such as sorbitan fatty acid esters, glycerin fatty acid esters, or alkyl Examples include cationic surfactants such as trimethylammonium chloride and alkyldimethylamine acetate bedine, and amphoteric surfactants.

The acrylonitrile polymer obtained by emulsion polymerization is subjected to coagulation treatment to separate the polymer fibers, thoroughly washed with water and dehydrated, and then the residual polymer contained in the polymer is evaporated as much as possible. It is necessary. To remove the residual emulsifier from the polymer, a method of heat treatment using the sound of a dryer, preferably under reduced pressure, a method of treatment using an extruder equipped with a degassing mechanism, etc. can be adopted.

The transpiration treatment referred to here means that when an acrylonitrile polymer is heated and melted and discharged into a spinning tower with a spinning hole to form a filament, no evaporation of the emulsifier is observed from the filament.
This refers to treatments such as thread cutting that do not cause a decrease in spinnability. Specifically, the amount of residual emulsifier needs to be 1000 ppm or less based on the polymer weight ff1K. If the amount of residual emulsifier exceeds 11,000 pp' (l-), foaming becomes significant, thread breakage occurs frequently, and spinning stability decreases.

The acrylonitrile polymer, which has undergone the evaporation treatment of the residual emulsifier in this way, is preformed into powder or pellet form, then supplied to an extruder, discharged from the nozzle hole, and subjected to stretching and heat setting. F. Can produce the acrylonitrile fiber that is the object of the present invention. ◎ The discharge rate of the polymer during bath melt spinning is 20 to 100? /l/min, and hot water stretching, steam stretching, hot plate stretching, hot bottle stretching, etc. can be adopted as the stretching method. The spinning temperature varies depending on the properties of the acrylonitrile polymer used, but a temperature range of 150 to 250°C is appropriate, and the IvJ speed can be 800 to 5000 m/min, making it possible to spin conventional acrylic fibers. This enables significantly higher speed spinning than speeds of 30 to 200 m/min.

In addition, in the case of acrylonitrile fibers obtained by wet spinning or dry spinning, an additional annealing process is required to burn out voids formed in the fibers, but bath melt spinning in the present invention The use of this method has the great advantage that fibers with sufficient performance can be produced without using an annealing process.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples. In addition, "U part" in the text indicates parts by weight.

The breaking strength and breaking elongation were measured using a Tensilon type tensile tester at a paper length of 20 m+, a tensile speed of 20 rpas/min, and a measurement atmosphere of 20° C. and 65° RH.

The reduced viscosity of the polymer was measured by the method described above.

Example 1 300 parts of distilled water was placed in a reaction vessel equipped with a stirrer and a reflux condenser,
3 parts of sodium dioctyl sulfuccinate, 5M peroxide, 015 parts of potassium acid, 42.5 parts of acrylonitrile, 7.5 parts of methyl acrylate, and 1 part of lauryl mercaptan were charged, and after purging the inside of the container with nitrogen, the inside of the container was stirred. The temperature was raised to 65°C and the entire visit began. After 15 minutes while controlling the temperature, 85 parts of acrylonitrile, 15 parts of methyl acrylate, and 2 parts of lauryl mercaptan'f were added over 1 hour, and after the addition was complete, stirring was continued for 2 hours to complete the polymerization. After cooling, the mixture was salted out using aluminum chloride, filtered, washed, and dried to obtain a polymer powder. The reduced viscosity of the polymer is [174 and the residual emulsifier i is 30
00 ppm'''C.

Next, this polymer was fed to a twin-screw extruder with a vent on top, and 23
The emulsifier is completely evaporated at a melting temperature of 0°C and then molded into pellets. The residual emulsifier t of the pellet is 1 o o o p
It was below pm.

The obtained f″L pellets were fed to a screw-type melt extruder, and the die hole diameter was α3smφ, the number of die holes was 72, and L/D=
2. Die sew spinning temperature 240℃, winding speed 1500m
/min to obtain undrawn yarn of 53 denier. Thereafter, the undrawn yarn was heated to 130° C. and stretched 10 times using a thermothermal plate to obtain a drawn yarn. The obtained n-thickness drawn yarn had no voids and had a good molded appearance. The physical properties of this drawn yarn are shown in Table 1.

Table 1 Comparative Example 1 The entire polymer powder obtained in Example 1 was fed to a screw-type melt extruder without evaporating the emulsifier, and an undrawn yarn was obtained in the same manner as in Example 1. During foaming, yarn breakage occurred during spinning, and the spinning stability was poor. Further, the obtained double-drawn yarn also had many voids and did not have satisfactory physical properties t=N.

[Effects of the present invention]

It is more difficult to use the present invention than in the past.
Melt spinning of acrylonitrile-based polymers has become possible. In addition, the spinning speed becomes extremely high, which not only increases productivity, but also eliminates the use of bath additive kumquats in the spinning process, which is extremely advantageous both in terms of equipment and economy. Furthermore, since the solvent removal process, which is essential in conventional wet or dry spinning methods, is not carried out, the resulting yarn is void-free and dense, and its yarn strength and elongation are comparable to those of conventional methods. You can get something similar to that.

Claims (1)

[Claims] 1. Emulsion polymerization of 40 to 95% by weight of acrylonitrile and 5 to 60% by weight of another copolymerizable monomer in the presence of an emulsifier that evaporates by heat treatment. The obtained acrylonitrile-based polymer having a reduced viscosity of 0.2 to 1.0 is heat-treated at a temperature higher than the melting temperature of the polymer to evaporate the emulsifier contained in the polymer, and then the polymer is melted. 1. A method for producing acrylonitrile fiber, the method comprising melt spinning at a temperature higher than that temperature. 2. The manufacturing method according to claim 1, wherein the amount of residual emulsifier after heat treatment is 1000 ppm or less.