JPH10195231A - Production of polyolefin-based porous molding product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject molding product having pores with a large diameter in a good productivity by melting and kneading a polyolefin resin with a water-soluble polymer and a solubilizing agent and molding the kneaded material and removing the water-soluble polymer in the molding product. SOLUTION: (A) A polyolefin resin having preferably 0.1-10 melt index (MI) (e.g. polypropylene resin) in an amount of 35-85 pts.wt. is melted and kneaded with (B) 10-60 pts.wt. water-soluble polymer which is a thermoplastic polymer, preferably having <=10 MI and containing polyvinyl alcohol component and (C) 5-30 pts.wt. solubilizer for solubilizing the components A and B (e.g. a block polymer of a polyolefin and a polyether) to provide a melted mixture. Then, the melted mixture is molded by discharging, e.g. from an extruder to provide a molding product. Then, the molding product is immersed in water and the component B in the molding product is removed by extraction and as necessary, the molding product is dried to provide the objective polyolefin-based porous molding products.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyolefin porous molded article used for various filters for fluids.

[0002]

2. Description of the Related Art Filters for gas and liquid fluids are used in air conditioners, the food industry, the electronics industry, wastewater treatment and other various fields. Use of a porous molded body such as a film has been performed. For example, a porous hollow fiber or a porous film using cellulose acetate, polysulfone, or the like is used for liquid treatment such as filtration, ultrafiltration, and dialysis, and gas treatment such as gas separation. The production of these porous molded bodies is mainly performed by a wet method. That is,
After dissolving the above polymers in a solvent, it is discharged into a coagulation bath from a nozzle or a die, immersed and coagulated, and then the volatiles of the solvent contained therein are removed from the coagulated body, and a hollow fiber or a porous film and How to In this method, when the polymer of the raw material is a polyolefin resin, the solubility in a solvent cannot be improved, and the mixed liquid tends to have a non-uniform composition, so that the mixed liquid may be discharged from a nozzle or a die. It is difficult to perform uniformly, so the coagulated body obtained in the coagulation bath also becomes non-uniform, the distribution of pores formed in the trace of the solvent removed therefrom is different, and it is possible to obtain a uniform porous molded body. There is a problem that can not be.

[0003]

As a method for solving such a problem, a molding method by melting is often used. That is, this method is a method in which a polyolefin resin is melt-molded and then stretched to stretch an amorphous portion, thereby forming strip-shaped micropores in a weak portion of the structure that cannot be stretched. However, in this method, the size and number of micropores and the distribution thereof vary depending on the temperature at the time of stretching, the degree of stretching, the film thickness of the molded body, and the like. Therefore, there is a problem that the size of the micropores can be reduced to only about 0.1 μm, so that the size of the micropores cannot be increased so much, and the thickness of the compact is limited. Further, as another manufacturing method of a porous molded body using a polyolefin resin,
A method has also been proposed in which a molten mixture of a polyolefin resin mixed with a liquid oil is molded, then cooled, and a liquid material in the molded body is extracted and removed with a solvent. However, in this method, if the amount of the liquid oil is too large, the material strength at the time of molding becomes weak, and a molded body having a desired strength cannot be obtained. There is a problem that it cannot be made larger than 1 μm.

A first object of the present invention is to provide a method for producing a polyolefin porous molded article having fine pores having a large pore diameter. A second object of the present invention is to provide a method for producing a polyolefin-based porous molded body, which can widely select a molded body shape such as a film thickness and a thickness in a film, a plate, a hollow fiber, a tubular body, and the like. It is in.
A third object of the present invention is to provide a method for producing a polyolefin-based porous molded body that can easily set conditions, has good productivity, and has a uniform size, number, and distribution of micropores.

[0005]

According to the present invention, there is provided (1) a polyolefin resin (A) 35 for solving the above-mentioned problems.
A melt-mixing step of melt-mixing the water-soluble polymer (B) with 10 to 60 parts by weight and the compatibilizer (C) with which the component (A) and the component (B) are compatible with each other. And a method for producing a polyolefin-based porous molded article, comprising: a molding step of molding the molten mixture into a molded article; and a water-soluble polymer extraction / removal step of extracting and removing the component (B) in the molded article with water. Is what you do. The present invention also provides (2) the method for producing a porous molded article according to (1), wherein the water-soluble polymer (B) is a polymer containing a polyvinyl alcohol component, (3), wherein the compatibilizer (C) is a polyolefin. The present invention provides a method for producing a polyolefin-based porous molded article according to the above (1) or (2), which is a block polymer composed of a polyether and a polyether.

Next, the present invention will be described in detail. In the present invention, the “polyolefin resin (A)” refers to a polypropylene resin, a polyethylene resin, or the like, and is not particularly limited. “Polyolefin-based porous molded article” means a porous molded article containing a polyolefin resin as a main component. The MI (melt index) is 0.1 in terms of molding workability.
1-10 polyolefin resins are preferred. In the present invention, the “water-soluble polymer (B)” is not particularly limited as long as it is a high-molecular-weight water-soluble polymer having a certain level of strength and moldability.
0) is preferred. In particular, a thermoplastic polymer containing a polyvinyl alcohol component is preferable. In the present invention, the “compatibilizer (C)” is not particularly limited as long as it promotes the compatibilization of the polyolefin and the water-soluble polymer, but it is a block polymer of the polyolefin and the hydrophilic polymer. Is preferred. For example, a block polymer of polyolefin and polyether can be used.

The mixing ratio of the above components (A), (B) and (C) is 35 to 85 parts by weight for component (A), 10 to 60 parts by weight for component (B), and 5 to 60 parts by weight for component (C). 30 parts by weight. When the amount of the component (A) is less than 35 parts by weight, it is difficult to obtain a characteristic using a polyolefin resin as a general-purpose resin, and when the amount is more than 85 parts by weight, the number of micropores is too small. If the component (B) is less than 10 parts by weight, the number of micropores is too small, and
If it is more than 0 parts by weight, the number of micropores is too large. Also,
If the component (C) is less than 5 parts by weight, the components (A) and (B)
The compatibility of the components cannot be improved, and even if it exceeds 30 parts by weight, the effect of improving the compatibility does not increase much.

In order to produce the polyolefin porous molded article of the present invention, the above-mentioned polyolefin resin (A)
The water-soluble polymer (B) and the compatibilizer (C) are mixed, and for example, a commonly used blender may be used. Next, the mixture may be melted and further mixed by a melt mixer, and may be discharged and molded by a usual method from an extruder equipped with a hollow fiber spinning nozzle, a film or sheet forming die. Further, the obtained molded body is immersed in water to extract and remove the water-soluble polymer in the molded body. At this time, the dissolution rate of the water-soluble polymer can be accelerated by using hot water. And
The molded body subjected to the extraction treatment is taken out and dried by a commonly used drying method such as air drying, blast drying, and vacuum drying to complete a polyolefin-based porous molded body.
When the polyolefin-based porous molded article is manufactured in this manner, since the water-soluble polymer (B) is used, the polyolefin-based porous molded article itself has moldability, and is easier to mold than when a solvent or liquid oil is used as described above. Thus, it is possible to widen the selection range of the shape of the molded product of the film or the hollow fiber, for example, it is possible to produce a plate having a thickness of several mm or a tubular body having an outer diameter and an inner diameter larger than that of the hollow fiber. Further, by using the component (C), the compatibility between the component (A) and the component (B) is improved, and a good dispersion state of each component is obtained in a molten mixture of these components, and the mixture is molded in that state. Therefore, the size, the number, and the distribution of the fine pores are easily uniform in the porous molded body obtained through the subsequent steps. Further, water can be used to extract and remove the component (B), and the temperature can be changed to adjust the extraction speed. Along with the fact that the strength does not need to be reduced like liquid oil and that there is no need to balance the manufacturing conditions as in the above-mentioned drawing method, complicated process condition management is not necessary, and various It is also easy to produce a porous molded body having a shape,
The effect of being able to manufacture a porous molded body having fine pores as large as 10 μm is great. Also,
Since there is no need to use an organic solvent or liquid oil, there is no problem of post-treatment and the productivity is good.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As will be described in detail in the following examples, since the water-soluble polymer (B) is used, its own moldability and strength are far superior to those of solvents and liquid oils. Since extraction and removal can be performed, it is easy to set the conditions of the micropore forming step, and the compatibility of the polyolefin resin (A) and the component (B) is improved by the compatibilizer (C). And the polyether is hydrophilic and has an affinity for the water-soluble polymer (B), and the component (C) has an affinity for both the component (A) and the component (B). To improve the mixing) to obtain a molded product composed of a uniform composition, which is used not only for porous hollow fibers and films using the component (A) of a general-purpose resin, but also for polyolefin-based materials such as tubular bodies and plates. The shape of the porous compact Obtained by widening the selection range of the pore diameter of the micropores.

[0010]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. All parts in each example are parts by weight. Example 1 47 parts of polypropylene resin (MI 0.5), 42 parts of thermoplastic polyvinyl alcohol (MI 2), polypropylene / polyether block type polymer (MI20) 1
1 part of methylene bisstearic acid amide (lubricant) was mixed in a blender, and the mixture was mixed in an extruder for 2 hours.
The mixture was melt-kneaded at 10 ° C. to produce pellets. The pellets are formed by an extruder equipped with a hollow fiber forming nozzle, and are formed into a hollow fiber shaped body (a fiber diameter of 1 mmφ, a film thickness of 150 μm)
m). This molded body was immersed in hot water of 70 ° C. for 12 hours, and then dried at 60 ° C. for 6 hours with a blow dryer to obtain a porous hollow fiber. When this porous hollow fiber was examined by a photographic method, the porosity was 41% and the average fine pore diameter was 20%.
μm.

Example 2 In Example 1, a polypropylene resin (MI 0.
5) 67 parts, thermoplastic polyvinyl alcohol (MI
0.4-0.7) 27 parts, a polypropylene / polyether block type polymer (MI 20) 6 parts, and methylene bisstearic acid amide 3 parts, except that the hollow fiber-shaped molded article (filament diameter 1 mmφ, membrane 130 μm). The molded body was subjected to the extraction and removal treatment in the same manner as in Example 1 and then dried to obtain a porous hollow fiber. When the porous hollow fiber was measured in the same manner as in Example 1, the porosity was 26.
%, The average micropore diameter was 6 μm.

Example 3 In Example 1, a polypropylene resin (MI 2) 3
2 parts, thermoplastic polyvinyl alcohol (MI 10) 6
Pellets were produced in the same manner except that 0 parts, 8 parts of a polypropylene / polyether block type polymer (MI 20) and 3 parts of methylene bisstearic acid amide were used. A molded body (1 mm thick) was produced. The molded body was subjected to the extraction removal treatment in the same manner as in Example 1, and then dried to obtain a porous sheet-shaped molded body. The porous body was measured in the same manner as in Example 1. The porosity was 64% and the average fineness was small. The pore size was 40 μm.

Example 4 In Example 3, a polypropylene resin (MI 2) 3
2 parts, thermoplastic polyvinyl alcohol (MI 10) 5
A sheet-like molded product (1 mm thick) was obtained in the same manner except that 0 part, 10 parts of a polypropylene / polyether block type polymer (MI 20), and 3 parts of methylene bisstearic acid amide were used. The molded body was subjected to the extraction and removal treatment in the same manner as in Example 1 and then dried to obtain a porous sheet-shaped molded body. The porous body was measured in the same manner as in Example 1. The pore size is 30 μm
Met.

Comparative Example 1 A hollow fiber-shaped molded product was obtained in the same manner as in Example 1, except that thermoplastic polyvinyl alcohol was not used and methylene bisstearic acid amide was used in two parts. The molded product was subjected to the extraction and removal treatment in the same manner as in Example 1, and then dried. As a result, the elution by water was almost zero.

Comparative Example 2 A hollow fiber shaped article was produced in the same manner as in Example 1 except that a polypropylene / polystyrene block type polymer (polystyrene was a hydrophobic polymer) was used instead of the polypropylene / polyester block type polymer. When the molding was performed, the strand discharged from the spinning nozzle could not be continuously wound up, and only a short strand was obtained (yarn diameter 5 mmφ, film thickness 1 mm). The molded body was subjected to extraction removal treatment in the same manner as in Example 1 and then dried. As a result, the porosity was 47%. Microporous areas were clearly visible.

Comparative Example 3 A hollow fiber molded article was molded in the same manner as in Example 1 except that polypropylene was used in 69 parts and soybean oil was used in place of thermoplastic polyvinyl alcohol in 20 parts. The discharged strand was completely impossible to wind up continuously, and soybean oil flowed out at the nozzle outlet in a liquid state. The solid portion was immersed in a methyl ethyl ketone solvent, and the soybean oil was extracted and removed, followed by drying. As a result, the porosity was 10%.

[0017]

According to the present invention, a water-soluble polymer is extracted and removed with water from a molded product obtained from a molten mixture of a polyolefin resin and a water-soluble polymer in combination with a compatibilizing agent thereof. As it is manufactured, it can have fine pores with large pore size, films, plates and hollow fibers,
It is possible to obtain a porous molded body in which the shape of the molded body such as a thickness and a thickness can be widely selected in a tubular body and the like, and the conditions can be easily set, and not only the productivity is good, but also the size of the fine pores is improved. A method for producing a polyolefin-based porous molded article having a uniform number and distribution can be provided.

Claims (3)

[Claims] 1. A polyolefin resin (A) in an amount of 35 to 85 parts by weight, a water-soluble polymer (B) in an amount of 10 to 60 parts by weight, and a compatibilizer (C) 5 for making the components (A) and (B) compatible with each other.
A melt mixture forming step of melt mixing up to 30 parts by weight, a forming step of forming the melt mixture into a formed body, and a water-soluble polymer extracting and removing step of extracting and removing the component (B) in the formed body with water. A method for producing a porous molded article having the same. 2. The method according to claim 1, wherein the water-soluble polymer (B) is a polymer containing a polyvinyl alcohol component. 3. The method according to claim 1, wherein the compatibilizer (C) is a block polymer comprising a polyolefin and a polyether.