JPS6324085B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing acrylic foam fibers by melt molding using a novel composition. The purpose is to provide a method for producing acrylic foamed fibers that are uniform and have a high degree of foaming at low cost. An acrylic polymer containing acrylonitrile as a main component is a polymer that is difficult to melt by heating, and its molding method is generally by dissolving it in a solvent and using a wet or dry method. Many attempts have been made to melt-mold acrylic polymers, including (1) a method of mixing an acrylic polymer solvent or an organic compound with a high dielectric constant as a plasticizer (Japanese Patent Publication No. 31-7065; No. Publication, USP2585499, USP338820), (2) Method using water as a plasticizer (USP2585444, JP-A-1972-
49839), (3) A method using a mixture of water and inorganic particles or water-soluble polymers as a plasticizer (Japanese Unexamined Patent Publication No. 1983-
Publication No. 9805, Japanese Unexamined Patent Publication No. 48-52832, US
P.3402231), etc. have been proposed. However, the above method has the following drawbacks in industrial application. That is, in the method (1) above, 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 a molded product with excellent physical properties can be obtained. For this purpose, 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. In method (2),
Although the plasticizer extraction step is not necessary, it is necessary to heat and melt at a temperature above the boiling point of water, so when extruded into a normal pressure zone, non-uniform foaming may occur, or water vapor may blow out from the spinning orifice, causing breakage. etc., it is difficult to stably obtain a uniform molded product. Method (3) is useful as a method for producing pulp-like fibers, but it is difficult to obtain long continuous so-called filaments. On the other hand, as a method for manufacturing expanded fibers of acrylic polymers, a method has been proposed in which water is used both as a plasticizer and a foaming agent. (Japanese Unexamined Patent Publication No. 54-93122) However, as mentioned earlier, in this method, if the amount of water is increased to increase the degree of foaming, there will be more cuts due to the blowing of steam, and if the amount of water is decreased, melting will occur. The viscosity of the product is high, making it difficult to mold, and at the same time, the degree of foaming is low, resulting in non-uniform foaming, making it difficult to stably obtain uniform foamed fibers with a high degree of foaming.
Therefore, in the conventional method, the foaming degree defined later is 3~
It has been difficult to stably produce foamed fibers with a high foaming degree of 10 or more. As a result of intensive research to solve the various problems mentioned above, the present inventors have discovered that a specific blended composition is suitable for melt molding, and that it is particularly capable of stably producing foamed fibers with a uniform and high degree of foaming. The inventors have discovered that the method is suitable for manufacturing, and have arrived at the present invention. That is, the gist of the present invention is as follows. 100 parts by weight of an acrylic polymer containing at least 40% by weight of acrylonitrile, 5 to 40 parts by weight of water, and 2 to 40 parts by weight of a phosphoric acid ester represented by the formula ()
20 parts by weight of an acrylic polymer composition PO (OR) ₃ ( ) In the formula, R is one or more monovalent organic groups selected from an alkyl group or an aryl group having 1 to 10 carbon atoms. 100 parts by weight of an acrylic polymer containing at least 40% by weight of acrylonitrile and 5 to 40 parts by weight of water;
After heating and melting an acrylic polymer composition consisting of 2 to 20 parts by weight of a phosphoric ester represented by the formula () and 20 parts by weight or less of an acrylic polymer solvent under autogenous pressure or a pressure higher than that,
A method for producing foamed fibers characterized by foaming and extrusion from a spinning orifice PO(OR) ₃ () In the formula, R is one or more monovalent organic groups selected from alkyl groups or aryl groups having 1 to 10 carbon atoms. It is the basis. 100 parts by weight of an acrylic polymer containing at least 40% by weight of acrylonitrile and 5 to 40 parts by weight of water;
An acrylic polymer composition consisting of 2 to 20 parts by weight of a phosphoric acid ester represented by the formula (), 20 parts by weight or less of an acrylic polymer solvent, and 0.1 to 50 parts by weight of at least one inorganic particle is heated under autogenous pressure or After heating and melting under higher pressure,
A method for producing foamed fibers characterized by foaming and extrusion from a spinning orifice PO(OR) ₃ () In the formula, R is one or more monovalent organic groups selected from alkyl groups or aryl groups having 1 to 10 carbon atoms. It is the basis. 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, cyclohexyl methacrylate methacrylic acid esters such as; methyl vinyl ketones; vinyl esters such as vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate; vinyl ethers such as methyl vinyl ether and ethyl vinyl ether; acrylamide and its alkyl substituted products ; 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, dimethylaminoethyl methacrylate; vinyl compounds such as acrolein, methacrolein, vinylidene cyanide, glycidyl methacrylate, methacrylonitrile, etc., and also includes mixtures thereof. In order to achieve the object of the present invention, the blending ratio of this acrylic polymer, water, phosphoric acid ester, solvent for the acrylic polymer, and inorganic particles is important. It is already known that water is used as a plasticizer and blowing agent, but when attempting to produce foamed fibers from a composition consisting only of acrylic polymer and water, as in the prior art, it is necessary to adjust the degree of foaming and melting. Since it is difficult to adjust the viscosity of the product in a consistent manner, it has not been possible to stably obtain foamed fibers with a high degree of foaming. In the present invention, in order to solve this problem, it is essential to include a phosphoric ester in addition to water. The blending ratio of each will be described below. The amount of water is 5 to 40 parts by weight per 100 parts by weight of the acrylic polymer. Preferably it is 10 to 30 parts by weight. If the amount of water exceeds 40 parts by weight, water vapor will blow out from the spinning orifice, or when extruding with a normal extruder, the water will separate and cause a backflow toward the raw material supply hopper, causing the raw material polymer to be eaten away. Problems such as defects occur frequently. If the amount of water is less than 5 parts by weight, the melt viscosity increases, making molding difficult and at the same time causing poor foaming. In addition, increasing the molding temperature in order to lower the viscosity is undesirable because decomposition and discoloration occur. The effect of blending phosphoric acid ester is that it is particularly characterized by controlling the melt viscosity during molding, and in the case of producing foamed fibers, a product with a high degree of foaming having fine and uniform cells can be obtained. Solvents for acrylic polymers are known to lower the melt viscosity, but even if dimethylformamide is added, foaming with uniform and fine bubbles, as in the case of adding phosphoric acid ester, is known. No fibers are obtained. The phosphoric acid ester of the present invention is represented by the formula (), PO(OR) ₃ () where R is one or more monovalent groups selected from an alkyl group or an aryl group having 1 to 10 carbon atoms. is an organic group. For example, trimethyl phosphate, triethyl phosphate, tri-n-butyl phosphate, 2
-ethylhexyl phosphate, tris-2-chloroethyl phosphate, tricresyl phosphate, triphenyl phosphate and mixtures thereof, etc. can be used. Particularly preferred are triethyl phosphate, tri-n-butyl phosphate, tricresyl phosphate, and triphenyl phosphate. The blending amount of the phosphoric acid ester is 2 to 20 parts by weight per 100 parts by weight of the acrylic polymer. Preferably it is 5 to 15 parts by weight. When the blending amount is 20 parts by weight or more, increasing the amount further will have little effect, and on the contrary, the amount of phosphoric acid ester remaining in the molded product will increase, and the disadvantage that it will bleed onto the surface becomes noticeable. On the other hand, if it is less than 2 parts by weight, it will be the same as not adding it, and even if the amount of water is increased to lower the melt viscosity, the foaming failure will be extremely stable and a uniform molded product will not be obtained. Although the object of the present invention can be achieved by blending water and phosphoric acid ester with the acrylic polymer as described above, it is desirable to blend the acrylic polymer with a solvent in order to further improve the moldability. be.
The solvent for the acrylic polymer of the present invention is generally known, such as dimethylformamide, dimethylacetamide, dimethylsulfoxide, γ-
Butyrolactone, ethylene carbonate, sulfolane, etc. can be used. The amount of the solvent to be blended is up to 20 parts by weight per 100 parts by weight of the acrylic polymer. If the amount is 20 parts by weight or more, the viscosity lowering effect will be small even if the amount is increased further, and the disadvantage that the amount of solvent remaining in the molded product will increase and the physical properties of the molded product will deteriorate becomes noticeable, which is not preferable. Furthermore, in order to improve uniform foamability and moldability, it is more desirable to incorporate inorganic particles. The effect of blending inorganic particles is that, although the reason is not clear, the melt viscosity of the composition is further reduced and a uniform and fine foamed structure is obtained. The inorganic particles of the present invention are substantially insoluble in water and ethylene carbonate, and have an average particle size of
They are inorganic particles of 40μ or less. Specifically, calcium carbonate, magnesium carbonate, barium carbonate, kaolin, alumina, talc, titanium oxide, and mixtures thereof can be used. In particular, when calcium carbonate, kaolin, and talc are used, the above-mentioned effects of the present invention can be achieved. These are particularly desirable inorganic particles because of their remarkable effects. The optimal range of the amount of these inorganic particles to be blended varies depending on the type of inorganic particles used, but it is 0.1 to 50 parts by weight per 100 parts by weight of the acrylic polymer. is 0.1 to 20 parts by weight, preferably 0.2 to 15 parts by weight, and 5 to 50 parts by weight, preferably 5 to 40 parts by weight for kaolin and talc. If the amount exceeds the upper limit, the molded product will become brittle and the physical properties will significantly deteriorate. If the amount is below the lower limit, the above-mentioned effects of the present invention cannot be exhibited, and when foaming and extrusion is carried out, only uneven molded products with coarse bubbles due to foaming can be obtained. As described in detail above, in the present invention, it is important to blend the acrylic polymer, water, phosphoric acid ester, solvent for the acrylic polymer, and inorganic particles in a specific ratio as necessary. However, the purpose of the present invention cannot be achieved. In the present invention, the above-mentioned blended composition is heated and melted under autogenous pressure or higher pressure, and then foamed and extruded from a spinning orifice to produce foamed fibers. Various methods can be used for heating and melting and extruding. That is, (a) acrylic polymer, water, phosphate ester, and if necessary, a solvent for the acrylic polymer and inorganic particles are uniformly mixed in a suitable mixer such as a ball mill to form a powder composition. This composition is heated and melted in a closed container such as an autoclave having an outlet connected to a spinning orifice through a valve or under a pressurized atmosphere, and after melting. A method of extruding through an orifice by opening a valve; (b) a method of heating and melting the powder composition of (a) above in a sealed cylinder of a plunger-type extruder, and then extruding by lowering the plunger (c) A method in which the powdery granular composition of (i) above is supplied to a hopper of a screw extruder for molding, heated and melted while being transferred through a heating zone, and extruded from a spinning orifice; When using,
The acrylic polymer and, if necessary, inorganic particles are supplied from the hopper, and the water, phosphoric acid ester, and, if necessary, the solvent for the acrylic polymer are injected as an aqueous solution or water dispersion into an appropriate location midway through the extruder. A method can be adopted in which the material is injected through a hole, then heated and melted while being transferred through a heating zone, and then extruded. Although the object of the present invention can be achieved by any of the above methods, it is convenient to use a conventional single-screw or twin-screw extruder. The heating temperature is preferably 120℃ or higher and 200℃ or lower.
The temperature is 150℃ or higher and 190℃ or lower. At temperatures below 120°C, it is difficult to melt and mold, and at temperatures above 200°C, the decomposition and coloring of the polymer is markedly insubstantial. In addition, when extruding from the spinning orifice, a measuring device such as a gear pump can be used as necessary. Any type of spinning orifice can be used, including one with a single hole, one with multiple holes, one with a circular cross section, and one with a non-circular (so-called irregularly shaped) cross section. The extrusion atmosphere is preferably air at normal pressure. The foam extruded in this manner is subjected to a stretching operation, if necessary. The stretching ratio (draft ratio) in this case is appropriately selected depending on the physical properties and thickness of the foamed fibers to be obtained. Furthermore, it is possible to carry out conventional stretching and heat treatment in a high-temperature atmosphere of 90° C. or higher, if necessary, either continuously or once rolled up. The foamed fibers obtained in this way not only have the characteristics of acrylic fibers, but also have excellent lightness, heat retention, and water absorption due to the uniform and fine foam structure, as well as a silky feel. It has a unique texture and luster, and is useful for a wide range of applications, such as handicraft fibers, wallpaper, rugs, and other interior textiles, water-absorbent fibers for clothing, and agricultural materials. . The present invention will be explained in more detail with reference to Examples below, but the scope of the present invention is not limited in any way by the description of these Examples. In addition, the degree of foaming described in the Examples is measured by the following method. The degree of foaming in the present invention is defined as the reciprocal (1/D) of the apparent density (D), measured by the following method. Method for measuring apparent density (D); From the sample to be measured, randomly collect 10 samples of 1 cm length along the length direction. Regarding each sample as a cylinder, measure the maximum diameter and minimum diameter of each sample and find the average value (d). From this average diameter, calculate the volume (υ) of each sample using the following formula. υ=πd ² /4 Furthermore, let the sum of each υ be the apparent volume (Vcm ³ ).
On the other hand, measure the total weight of 10 samples (Wg) and calculate the apparent density (D) using the following formula: D = W/V (g/cm ³ )
The melt viscosity was measured at 180 using a Koka type flow tester.
This is the apparent viscosity measured at ℃ and under an extrusion load of 30 kg/cm ² using an orifice having a pore of 1 mm in diameter and L/D=1. Example 1 90% by weight acrylonitrile, methyl acrylate
Using a 10% by weight acrylic polymer, a powder composition was prepared by uniformly mixing it using a ball mill at the compounding ratio shown in Tables 1 and 2, and the melt viscosity was measured using a Koka type flow tester. It was measured. The sample was melted by filling the sample into a cylinder at a predetermined temperature (180°C), plugging the orifice, and holding the cylinder for 2 minutes. Thereafter, the orifice was quickly uncorked and extrusion was started. The measurement results and the condition of the obtained extrudates are shown in Tables 1 and 2. All compositions are given in parts by weight. Example 2 15 parts by weight of water and 10 parts by weight of tricresyl phosphate for 100 parts by weight of an acrylic polymer consisting of 92% by weight of acrylonitrile and 8% by weight of methyl acrylate.
A composition containing parts by weight was prepared in the same manner as in Example 1, and the granular composition was supplied from a hopper to a single-screw extruder having three heating zones, and foaming extrusion was performed. Counting from the raw material supply hopper side, the first heating zone is 120℃, the second heating zone is 170℃, the third heating zone is 180℃,
The spinning orifice was set at 190°C. A spinning orifice having one pore with a diameter of 1 m/m was used for extrusion at an extrusion pressure of 60 Kg/cm ² . The extruded foamed extrudate was rolled up at 170 m/min to obtain foamed fibers. The spinning conditions and the degree of foaming of the obtained foamed fibers are summarized in Table 3 together with the results of other Examples. Example 3 In addition to adding 5 parts by weight of ethylene carbonate to 100 parts by weight of the acrylic polymer to the composition of Example 2, the same foaming extrusion as in Example 2 was carried out. The extrusion pressure was 40Kg/cm ² . The results are shown in Table 3. Example 4 For 100 parts by weight of the same acrylic polymer as in Example 2, 20 parts by weight of water and 5 parts by weight of triethyl phosphate.
An attempt was made to manufacture foamed fibers with a higher degree of foaming than in Example 2 by preparing a composition containing the following parts by weight. The extrusion equipment and conditions were the same as in Examples 2 and 3. The extrusion pressure was 45Kg/ ^cm2 .
Shown in the table. Comparative Example 1 A composition was prepared by blending 100 parts by weight of the same acrylic polymer as in Example 2 with 40 parts by weight of water, and extruded using the same equipment and conditions as in Example 2. Extrusion pressure varied in the range of 20-50 Kg/ ^cm2 . The results are shown in Table 3.

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Claims (1)

[Scope of Claims] 1. An acrylic polymer consisting of 100 parts by weight of an acrylic polymer containing at least 40% by weight of acrylonitrile, 5 to 40 parts by weight of water, and 2 to 20 parts by weight of a phosphoric acid ester represented by the formula () After heating and melting the composition under autogenous pressure or higher pressure,
A method for producing foamed fibers characterized by foaming and extrusion from a spinning orifice. PO(OR) ₃ () In the formula, R is one or more monovalent organic groups selected from an alkyl group or an aryl group having 1 to 10 carbon atoms. 2 The phosphoric acid ester is triethyl phosphate,
or tri-n-butyl phosphate or a mixture thereof. 3. The manufacturing method according to claim 1, wherein the phosphoric acid ester is tricresyl phosphate, triphenyl phosphate, or a mixture thereof. 4 100 parts by weight of an acrylic polymer containing at least 40% by weight of acrylonitrile and 5 to 40 parts by weight of water,
After heating and melting an acrylic polymer composition consisting of 2 to 20 parts by weight of a phosphoric ester represented by the formula () and 20 parts by weight or less of an acrylic polymer solvent under autogenous pressure or a pressure higher than that, A method for producing foamed fibers characterized by foaming and extrusion from a spinning orifice. PO(OR) ₃ () In the formula, R is one or more monovalent organic groups selected from an alkyl group or an aryl group having 1 to 10 carbon atoms. 5 The phosphoric acid ester is triethyl phosphate,
or tri-n-butyl phosphate or a mixture thereof. 6. The manufacturing method according to claim 4, wherein the phosphoric acid ester is tricresyl phosphate, triphenyl phosphate, or a mixture thereof. 7 100 parts by weight of an acrylic polymer containing at least 40% by weight of acrylonitrile and 5 to 40 parts by weight of water,
An acrylic polymer composition consisting of 2 to 20 parts by weight of a phosphoric ester represented by the formula (), 20 parts by weight or less of an acrylic polymer solvent, and 0.1 to 50 parts by weight of at least one inorganic particle is heated under autogenous pressure or A method for producing foamed fibers, which comprises heating and melting the fibers under a higher pressure, and then extruding the foamed fibers from a spinning orifice. PO(OR) ₃ () In the formula, R is one or more monovalent organic groups selected from an alkyl group or an aryl group having 1 to 10 carbon atoms. 8 The phosphoric acid ester is triethyl phosphate,
or tri-n-butyl phosphate or a mixture thereof. 9. The manufacturing method according to claim 7, wherein the phosphoric acid ester is tricresyl phosphate, triphenyl phosphate, or a mixture thereof. 10. The production method according to claim 7, wherein the inorganic particles are selected from calcium carbonate, barium carbonate, kaolin, alumina, and talc.