JPH0149183B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for melt molding acrylic polymer compositions. More specifically, the present invention relates to a method of melt molding an acrylic polymer composition that has suitable thermal stability during melt molding by blending a specific phosphorus component-containing compound into the acrylic polymer composition. An acrylic polymer containing acrylonitrile as a main component is a polymer that is difficult to melt by heating, and its molding method generally involves dissolving it in a solvent and using a wet or dry method. Many attempts have been made to melt-mold acrylic polymers, including a method in which a solvent for acrylic polymers or an organic compound with a high dielectric constant is mixed as a plasticizer (Japanese Patent Publication No. 7065/1989, USP 2585499, USP 33820), method using water as a plasticizer (USP 2585444, JP-A-48-
49839, Japanese Unexamined Patent Publication No. 54-93122), etc. have been proposed. However, the above method has the following drawbacks in industrial application. That is, in the above method, a large amount of plasticizer (for example, about the same amount as the polymer) must be used in order to make it substantially moldable, and in order to obtain a molded product with excellent physical properties, In this case, a plasticizer extraction and recovery process is essential. Although it is possible to reduce the amount of plasticizer and mold at high temperatures, the acrylic polymer decomposes and becomes discolored, making it extremely impractical. Although the plasticizer extraction step is not necessary in the method described above, since it is necessary to heat and melt the material at a temperature above the boiling point of water, foaming occurs when it is exposed to a normal pressure zone or extruded. Although it is possible to reduce the amount of water and mold at a high temperature in order to reduce foaming, this is also impractical because the acrylic polymer decomposes and becomes discolored. On the other hand, a method of producing foamed fibers by using water as both a plasticizer and a foaming agent in an acrylic polymer has been actively proposed in recent years. (Japanese Unexamined Patent Publication No. 54-93122) However, in this method, if the amount of water for foaming is increased, there will be many cuts due to the blowing of steam, and if the amount of water is decreased, the viscosity of the melt will be high and molding will occur. becomes difficult. Also, by heating the molten material to a high temperature,
Although it is possible to obtain fibers with a high degree of foaming, this method is also impractical because the acrylic polymer decomposes and becomes colored. The inventors of the present invention have conducted extensive research to solve the above-mentioned problems regarding decomposition and coloration of acrylic polymers, and have found that by blending a specific phosphorus component-containing compound, they have achieved excellent thermal stability during melt molding. The present invention was achieved based on the discovery that this shows the properties of the compound. That is, the present invention provides a composition comprising an acrylonitrile polymer containing at least 40% by weight of acrylonitrile and a plasticizer, which contains 0.1 to 5% by weight of phosphoric acid or phosphoric acid ester based on the acrylic polymer. This is a melt molding method for acrylic polymers, which is characterized by melting. The present invention will be explained in more detail below. The acrylic polymer referred to in the present invention refers to acrylonitrile alone or at least acrylonitrile.
It contains 40% by weight or more, more preferably 60% by weight or more of bonds, and the remainder consists of at least one ethylenically unsaturated compound. Here, ethylenically unsaturated compounds include vinyl halides and vinylidene halides such as vinyl chloride, vinyl bromide, vinyl fluoride, and vinylidene chloride; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, and itaconic acid. Acids and their salts; methyl acrylate,
Acrylic acid esters such as ethyl acrylate, butyl acrylate, octyl acrylate, methoxyethyl acrylate, phenyl acrylate, cyclohexyl acrylate; butyl methacrylate, octyl methacrylate, methoxyethyl methacrylate, phenyl methacrylate, methacrylic acid Methacrylic acid esters such as cyclohexyl; Methyl vinyl ketones; Vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, and vinyl benzoate; Vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; Acrylamide and its alkyl substitution Unsaturated sulfonic acids such as vinyl sulfonic acid and p-styrene sulfonic acid and their salts; Styrene and its alkyl or halogen substituted products such as styrene, α-methylstyrene and chlorostyrene; Allyl alcohol and its esters or ethers Basic vinyl compounds such as vinylpyridine, vinylimidazole, and dimethylaminoethyl methacrylate; Vinyl compounds such as acrolein, methacrolein, vinylidene cyanide, glycidyl methacrylate, and methacrylonitrile, including mixtures thereof. . The effect of the plasticizer is to plasticize and melt the acrylic polymer, and the plasticizers used in the present invention are generally known, such as water, dimethylformamide, dimethylacetamide, dimethylsulfoxide, γ- Butyrolactone, ethylene carbonate, sulfolane, etc. are used, but especially water, dimethylformamide, dimethyl sulfoxide, and ethylene carbonate have excellent plasticity for acrylic polymers, and the amount can be arbitrarily selected depending on the purpose of use. . In order to achieve the object of the present invention, by incorporating phosphoric acid or phosphoric acid ester into the acrylic polymer and plasticizer, it is possible to have excellent thermal stability during melt molding. The phosphoric acid referred to in the present invention is generally known, and specifically includes metaphosphoric acid, orthophosphoric acid, triphosphoric acid, tetraphosphoric acid, polyphosphoric acid, and the like.
Phosphate esters include triphenyl phosphate, butyl acid phosphate, butoxyethyl acid phosphate, 2-ethylhexyl acid phosphate, β-chloroethyl acid phosphate, di(2-ethylhexyl) phosphate, Acidic phosphoric acid esters such as ethylene glycol acid phosphate and (2-hydroxyethyl) methacrylate acid phosphate;
Triethyl phosphite, tri-n-butyl phosphite, triphenyl phosphite, tristearyl phosphite, tridecyl phosphite, diphenyldecyl phosphite, distearyl pentaerythrityl diphosphite, tetraphenyl dipropylene glycol diphosphite , dilauryl hydrogen phosphite, tris (2-ethylhexyl) phosphite, tris (nonylphenyl) phosphite, diphenyl mono (tridecyl) phosphite, bisphenol A pentaerythritor phosphite, etc., and mixtures thereof. Also includes. Among these, tridecyl phosphite, dilauryl hydrogen phosphite, diphenyldecyl phosphite, and triphenyl phosphite are particularly excellent in thermal stability during melt molding. Next, the blending ratio of these phosphoric acids or phosphoric esters will be described. The amount of phosphoric acid or phosphoric acid ester in the composition consisting of the acrylic polymer and plasticizer is 0.1 to 5% by weight, preferably 0.2 to 2% by weight, based on the acrylic polymer. If the amount of phosphoric acid or phosphoric acid ester is less than 0.1% by weight, the thermal stability will be insufficient.
In addition, if it exceeds 5% by weight, so-called blooming, which causes discharge and leakage to occur on the surface of the final product over time, will occur, and so-called plate-out, which will stick to the surface of the mold during processing and will not peel off, will occur. This is not desirable because it occurs. The present invention exhibits extremely excellent thermal stability when the above composition is melt-molded at a general melt-molding temperature for acrylic polymers. Various methods can be used to heat-melt and mold the compositions described above. That is, acrylic polymer and plasticizer are blended with phosphoric acid or phosphoric acid ester in a specific ratio, and mixed uniformly in a suitable mixer such as a ball mill to form powder and granules.
Alternatively, a composition in the form of a solution is prepared, and the composition is (a) sealed or processed in a sealable container such as an autoclave, which has an outlet connected to a spinning orifice via a valve. A method of heating and melting in a pressure atmosphere, opening a valve after melting and extruding from an orifice, (b) a method of heating and melting in a sealed cylinder of a plunger type extruder, and then lowering the plunger and extruding. (c) A method of supplying to the hopper of a screw extruder for molding, heating and melting while transferring it through a heating zone, and extruding from a spinning orifice;
(d) A method of directly connecting a mold for molding after the orifice of (a), (b), and (c) above and injecting into the mold for molding can be adopted.
In addition, when extruding from the spinning orifice, a measuring device such as a gear pump can be used as necessary. Further, the molded product may be subjected to stretching operation and heat treatment as necessary. As described above in detail, the present invention is capable of imparting excellent thermal stability during melt molding by blending phosphoric acid or phosphate ester with an acrylic polymer and a plasticizer, and melt molding the acrylic polymer and plasticizer. This method is noteworthy as a method for melt molding acrylic fibers and acrylic resins, and will be widely used in the future as a method for melt molding acrylic fibers and acrylic resins. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the scope of the present invention is not limited in any way by the description of these Examples. It should be noted that the degree of coloration described in the Examples was measured by the following method. The degree of coloration in the present invention is defined as the absorbance (AS) at a wavelength of 406 nm in the visible light region measured by the following method. How to measure absorbance: Scrape off the sample to be measured with a knife and
g was measured using a precision balance, placed in a 25 ml Erlenmeyer flask, and 20 ml of concentrated nitric acid was added thereto, followed by stirring with a magnetic stirrer to dissolve the sample. The solution is placed in a 1 cm rectangular glass cell and the absorbance at a wavelength of 406 nm is measured using a spectrophotometer using concentrated nitric acid as the reference standard solution. Example 1 Using an acrylic polymer consisting of 92% by weight of acrylonitrile and 8% by weight of methyl acrylate, a powdery composition was prepared by uniformly mixing using a ball mill at the blending ratio shown in Table 1. Inner diameter 16
The mixture was placed in a stainless steel container with a diameter of 50 mm and a length of 50 mm, sealed tightly, and melted in a wood metal bath kept at 200°C. Thereafter, after one hour, the container was taken out of the wood metal bath, cooled in water, and then the stopper of the container was opened and the molded product inside was taken out. Table 1 shows the degree of coloring and appearance color of the molded product taken out. All compositions are expressed in weight percent relative to the acrylic polymer. Example 2 Using the same acrylic polymer as in Example 1, a composition was prepared in the same manner as in Example 1 at the blending ratio shown in Table 1, and the composition was tested using a Koka type flow tester to obtain a composition with a diameter of 1
Melt extrusion was carried out using an orifice having pores of mm, L/D=1. In addition, when melting the sample,
After filling the cylinder at 240°C, the orifice was plugged and held for 6 minutes. After that, quickly remove the orifice plug and press the extrusion load to 30Kg/
It was extruded under the condition of ^cm2 . Table 1 shows the degree of coloration and appearance color of the obtained extrudate. All compositions are expressed in weight percent relative to the acrylic polymer. 【table】

Claims (1)

[Claims] 1. A composition comprising an acrylic polymer containing at least 40% by weight of acrylonitrile and a plasticizer, containing 0.1 to 5% by weight of phosphoric acid or phosphoric acid ester based on the acrylic polymer. A method for melt-molding an acrylic polymer composition, which is characterized by melting. 2. The method of melt molding an acrylic polymer composition according to claim 1, wherein the plasticizer is water, dimethylformamide, dimethyl sulfoxide, ethylene carbonate, or a mixture thereof. 3 The phosphoric acid ester is tridecyl phosphite,
Claim 1 which is dilauryl hydrogen phosphite, diphenyldecyl phosphite, triphenyl phosphate and mixtures thereof.
Melt molding method of the acrylic polymer composition described in 2.