JPS6328124B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing expanded fibers by melt molding using a novel acrylic polymer composition. The purpose is to provide a method for producing acrylic foam fibers that are uniform and have a high degree of foaming at low cost. Acrylic polymers containing acrylonitrile as a main component are difficult to melt by heating, and the general method for molding them is to dissolve them in a solvent and use a wet or dry method. Conventionally, many attempts have been made to melt-mold acrylic polymers. For example, (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.
Publication No. 7065, USP2585499, USP338820), (2)
Method using water as a plasticizer (USP2585444, JP-A-Sho
48-49839), (3) A method using a mixture of water and inorganic particles or water-soluble polymers as a plasticizer (Japanese Unexamined Patent Application Publication No. 1973)
-9805 Publication, JP 48-52832 Publication, US
P.3402231), etc. have been proposed. However, all of the above methods have the following drawbacks for industrial application. That is, in the method (1) above, a large amount of plasticizer (e.g., 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 must be heated and melted at a temperature above the boiling point of water, so if it is extruded into a normal pressure zone, non-uniform foaming may occur, or water vapor may blow out from the spinning orifice, causing breakage. It is difficult to stably obtain a uniform molded product. Also (3)
Although this method is useful as a method for producing pulp-like fibers, 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, with conventional methods, only a foaming degree defined in the present invention of about 3 to 5 can be obtained, and it is difficult to stably produce foamed fibers with a high foaming degree of 10 or more. It was hot. The present inventors have conducted extensive research to solve these various problems, and have found that an acrylic polymer composition consisting of a specific formulation is suitable for melt molding, and has a particularly uniform and high foaming degree. They found that it is suitable for stably obtaining foamed fibers having . 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 and 5 to 40 parts by weight of water;
and an acrylic polymer composition consisting of 2 to 20 parts by weight of dibasic acid esters represented by formulas () and (), heated and melted under autogenous pressure or higher pressure, and then foamed and extruded from a spinning orifice. _{A method} for _producing expanded fibers _{from an} acrylic polymer composition characterized by is one or more monovalent organic groups selected from the group, and n is an integer of 2 to 10. 100 parts by weight of an acrylic polymer containing at least 40% by weight of acrylonitrile, 5 to 40 parts by weight of water, 2 to 20 parts by weight of a dibasic acid ester represented by formulas () and (), and 20 parts by weight of a solvent for the acrylic polymer.
Production of foamed fibers from an acrylic polymer composition, characterized by heating and melting an acrylic polymer composition comprising 1 part by weight or less under autogenous pressure or higher pressure, and then foaming and extruding it from a spinning orifice. Method C ₆ H ₄ (COOR) ₂ () ROOC (CH ₂ ) _o COOR () 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; , n is an integer from 2 to 10. 100 parts by weight of an acrylic polymer containing at least 40% by weight of acrylonitrile, 5 to 40 parts by weight of water, 2 to 20 parts by weight of a dibasic acid ester represented by formulas () and (), and 20 parts by weight of a solvent for the acrylic polymer. and at least one inorganic particle
0.1 to 50 parts by weight of an acrylic polymer composition is heated and melted under autogenous pressure or higher pressure, and then foamed and extruded from a spinning orifice. C ₆ H ₄ (COOR) ₂ () ROOC(CH ₂ ) _o COOR () In the formula, R is one or more monovalent organic groups selected from alkyl groups or aryl groups having 1 to 10 carbon atoms, and n is 2 to 10 carbon atoms. It is an integer of 10. 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 esters such as ethyl acrylate, butyl acrylate, ocryl 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 Groups: 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. . In order to achieve the object of the present invention, the blending ratio of this acrylic polymer, water, dibasic acid ester, solvent for the acrylic polymer, and inorganic particles is important. When attempting to produce foamed fibers from a composition containing only an acrylic polymer and water as in the prior art, it is extremely difficult to adjust the foaming degree and the viscosity of the melt in a consistent manner. It is not possible to stably obtain foamed fibers with a high degree of foaming. An important feature of the production method of the present invention is that a dibasic acid ester is blended into the acrylic polymer composition in order to obtain expanded fibers with a high degree of foaming. In addition, the amount of water in the composition is based on the amount of water in the acrylic polymer.
The amount is 5 to 40 parts by weight per 100 parts by weight. Preferably it is 10 to 30 parts by weight. If the water exceeds 40 parts by weight, water vapor may blow out from the spinning orifice.
When extrusion molding is performed using a normal extruder, problems such as water separation and backflow to the raw material supply hopper occur, resulting in poor penetration of the raw material polymer. 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. Furthermore, raising the molding temperature in order to lower the viscosity is extremely undesirable as decomposition and discoloration occur. The blending effect of dibasic acid esters is to adjust the melt viscosity during molding, and as a special feature, it is possible to obtain products with a high degree of foaming that have fine and uniform cells when producing foamed fibers. . Solvents for acrylic polymers are known to lower the melt viscosity, but even when dimethylformamide is added, uniform and fine bubbles remain as in the case of dibasic acid esters. Foamed fibers cannot be obtained. The dibasic acid ester of the present invention has the formula ()()
C ₆ H ₄ (COOR) ₂ () ROOC (CH ₂ ) _o COOR () In the formula, R is one or more selected from alkyl groups or aryl groups having 1 to 10 carbon atoms. It is a valent organic group, and n is an integer of 2 to 10. For example, dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dibutyl phthalate, diheptyl phthalate, dioctyl phthalate, dinonyl phthalate, diisodecyl phthalate, dioctyl succinate, diisodecyl succinate, dioctyl adipate, diisodecyl adipate, dioctyl azelate, dibutyl sebacate, Dioctyl sebacate and mixtures thereof can be used. The amount of the dibasic acid ester blended 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. If the blending amount is 20 parts by weight or more, increasing the amount further will have little effect; on the contrary, the amount of dibasic acid ester remaining in the molded product will increase, and the drawback of oozing out onto the surface will become more 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 melt viscosity is lowered by increasing the amount of water, foaming will be insufficient and a stable and uniform molded product will not be obtained. Although the object of the present invention can be achieved by blending the above-mentioned acrylic polymer with water and dibasic acid ester, it is desirable to blend a solvent for the acrylic polymer in order to further improve 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 blending amount of the solvent is 20 parts by weight or less 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 referred to in the present invention are inorganic particles that are substantially insoluble in water and acrylic polymer solvents and have an average particle diameter of 40 μm 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 achieved, and when foaming and extrusion is carried out, only uneven molded products with coarse bubbles due to foaming are obtained. As described in detail above, in the present invention, it is important to blend the acrylic polymer, water, and dibasic acid ester in a specific ratio, and even if any of them is lacking, the desired effect of the present invention cannot be obtained. do not have. Furthermore, the effect can be increased by adding an acrylic polymer solvent and inorganic particles to the acrylic polymer composition. In the present invention, the above blended composition is heated and melted under autogenous pressure or higher pressure, and then foamed and extruded from a spinning orifice to obtain foamed fibers. Various methods can be used for heating and melting and extruding. That is, (a) a specific ratio of acrylic polymer, water, dibasic acid ester, 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 powder. A composition is prepared, and the 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. Method of opening the rear valve and pushing out from the orifice, (b) the above method.
(a) A method in which the powder or granular composition of (a) is heated and melted in a sealed cylinder of a plunger-type extruder, and then the plunger is lowered to extrude the powder or granular composition of (a). A method in which the acrylic polymer and, if necessary, inorganic particles are supplied to the hopper of a screw extruder for molding, heated and melted while being transferred through a heating zone, and extruded from a spinning orifice. is supplied from the hopper, and water, dibasic acid ester, and if necessary, the solvent for the acrylic polymer are injected as an aqueous solution through an injection hole provided at an appropriate location in the middle of the extruder, and then transferred through the heating zone. A method such as heating and melting and extruding can be adopted. 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 must be 150°C or higher and 190°C or lower.
Below 120°C, it will be difficult to melt and mold.
If the temperature is above 0.degree. C., the polymer will decompose and become colored, making it impractical. 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 (bluff ratio) in this case is appropriately selected depending on the physical properties, thickness, etc. 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 fiber thus obtained not only has the characteristics of an acrylic fiber, but also
Derived from its uniform and fine foam structure, it has a lightweight feel, excellent heat retention, and water absorption, as well as a unique texture and luster, such as a smooth feel, and is used for handicraft fibers, wallpaper, and rugs. It is useful for a wide range of applications, including interior textiles, water-absorbing 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. How to measure apparent density (D): From the sample to be measured, randomly collect 10 samples of 1 cm length along the length direction. Regard each sample as a cylinder, measure the maximum diameter and minimum diameter of each sample, and find the average value (d). The volume (v) of each sample is determined from this average diameter using the following formula. v=πd ² /4 Furthermore, let the sum of each v 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.
It is the apparent viscosity measured at ℃ under the condition of an extrusion load of 30 kg/cm ³ 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 fibrous extrudates are shown in Tables 1 and 2. Example 2 A composition in which 15 parts by weight of water and 10 parts by weight of dioctyl adipate were blended with 100 parts by weight of an acrylic polymer consisting of 92% by weight of acrylonitrile and 8% by weight of methyl acrylate was prepared in the same manner as in Example 1. A granular composition was prepared using a single-screw extruder having three heating zones, and the powdery granular composition was supplied from a hopper to carry out foaming extrusion. 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 180°C. A spinning orifice having one pore with a diameter of 1 mm was used for extrusion at an extrusion pressure of 50 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 A composition was prepared by adding 5 parts by weight of ethylene carbonate to 100 parts by weight of the acrylic polymer to the composition of Example 2, and foaming extrusion was performed using the same extrusion equipment and conditions as in Example 2. . Extrusion pressure is 40Kg/
It was warm in ^cm2 . The results are shown in Table 3. Example 4 A composition was prepared by blending 100 parts by weight of the same acrylic polymer as in Example 2 with 20 parts by weight of water and 10 parts by weight of dioctyl phthalate, and was foamed and extruded using the same equipment and extrusion conditions as in Example 2. I did this. The extrusion pressure was 60Kg/ ^cm2 . The results are shown in Table 3. Example 5 A composition in which 13 parts by weight of water and 12 parts by weight of dibutyl phthalate were mixed with 100 parts by weight of an acrylic polymer consisting of 93% by weight of acrylonitrile and 7% by weight of methyl acrylate was prepared in the same manner as in Example 1. The foam was extruded using the same equipment and extrusion conditions as in Example 2. The extrusion pressure was 50Kg/ ^cm2 . The results are shown in Table 3. Example 6 A composition was prepared by blending 100 parts by weight of the same acrylic polymer as in Example 5 with 11 parts by weight of water, 7 parts by weight of dimethyl phthalate, and 3 parts by weight of ethylene carbonate. Foaming extrusion was carried out using the equipment and extrusion conditions. Extrusion pressure is 60
It was Kg/ ^cm2 . The results are shown in Table 3. Example 7 A composition was prepared by adding 5 parts by weight of kaolin to 100 parts by weight of the acrylic polymer to the composition of Example 3, and foaming extrusion was performed using the same equipment and extrusion conditions as in Example 2. Summer. Extrusion pressure is 45
It was Kg/ ^cm2 . The results are shown in Table 3. Comparative Example 1 A composition was prepared by blending 40 parts by weight of water with 100 parts by weight of the same acrylic polymer as in Example 2,
Extrusion was carried out using the same equipment and extrusion conditions as in Example 2. The extrusion pressure varied from 20 to 50 Kg/ ^cm2 . The results are shown in Table 3. Comparative Example 2 A composition was prepared by blending 100 parts by weight of the same acrylic polymer as in Example 2 with 15 parts by weight of water and 5 parts by weight of ethylene carbonate, and extruded using the same equipment and extrusion conditions as in Example 2. . Extrusion pressure is 60
It was Kg/ ^cm2 . The results are shown in Table 3. Comparative Example 3 A composition was prepared by blending 13 parts by weight of water and 25 parts by weight of dioctyl phthalate with 100 parts by weight of the same acrylic polymer as in Example 2, and extruded using the same equipment and extrusion conditions as in Example 2. did. The extrusion pressure is
It was 40Kg/ ^cm2 . The results are shown in Table 3.

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Claims (1)

[Scope of Claims] 1. 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;
and an acrylic polymer composition consisting of 2 to 20 parts by weight of dibasic acid esters represented by formulas () and (), heated and melted under autogenous pressure or higher pressure, and then foamed and extruded from a spinning orifice. A method for producing foamed fibers from an acrylic polymer composition, characterized by: C ₆ H ₄ (COOR) ₂ () ROOC (CH ₂ ) _o COOR () 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, n is an integer from 2 to 10. 2. A method for producing expanded fibers from an acrylic polymer composition according to claim 1, wherein the dibasic acid ester is dioctyl adipate. 3. A method for producing expanded fibers from an acrylic polymer composition according to claim 1, wherein the dibasic acid ester is dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, or a mixture thereof. 4 100 parts by weight of an acrylic polymer containing at least 40% by weight of acrylonitrile, 5 to 40 parts by weight of water, and a dibasic acid ester represented by formulas () and () 2
After heating and melting an acrylic polymer composition consisting of ~20 parts by weight and 20 parts by weight or less of an acrylic polymer solvent under autogenous pressure or higher pressure,
A method for producing foamed fibers from an acrylic polymer composition, which comprises foaming and extruding from a spinning orifice. C ₆ H ₄ (COOR) ₂ () ROOC (CH ₂ ) _o COOR () 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, n is an integer from 2 to 10. 5. A method for producing expanded fibers from an acrylic polymer composition according to claim 4, wherein the dibasic acid ester is dioctyl adipate. 6. A method for producing expanded fibers from an acrylic polymer composition according to claim 4, wherein the dibasic acid ester is dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, or a mixture thereof. 7 100 parts by weight of an acrylic polymer containing at least 40% by weight of acrylonitrile, 5 to 40 parts by weight of water, and a dibasic acid ester represented by formulas () and () 2
An acrylic polymer composition consisting of ~20 parts by weight, 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 and melted under autogenous pressure or higher pressure. After
A method for producing foamed fibers from an acrylic polymer composition, which comprises foaming and extruding from a spinning orifice. C ₆ H ₄ (COOR) ₂ () ROOC (CH ₂ ) _o COOR () 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, n is an integer from 2 to 10. 8. A method for producing expanded fibers from an acrylic polymer composition according to claim 7, wherein the dibasic acid ester is dioctyl adipate. 9. A method for producing expanded fibers from an acrylic polymer composition according to claim 7, wherein the dibasic acid ester is dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, or a mixture thereof. 10 Inorganic particles include calcium carbonate, kaolin,
A method for producing expanded fibers from the acrylic polymer composition according to claim 7, which is selected from talc.