JPS627401A - Heat resistant hydrophilic porous polyolefin hollow yarn - Google Patents

Abstract

PURPOSE:To obtains a heat resistance hydrophilic porous polyolefin hollow yarn, by polymerizing an alkoxy(meth)acrylate polyethylene glycol compound and a compound containing a monomer copolymerizable therewith on the surface of a fibril to fix the formed copolymer to said fibril. CONSTITUTION:A porous polyethylene hollow yarn is immersed in a solutions prepared by dissolving a first component represented by formula A (wherein n is 10-100, R is a 12C or more alkyl group and R' is hydrogen or a methyl group) being an alkoxy acrylate polyethylene glycol and a second component being a monomer having at least two double bonds copolymerizable with the first component, for example, diacrylic acid tetraethylene glycol in a solvent and dried in air to remove the solvent and subsequently irradiated with electron beam to perform radiation polymerization. By this method, the polymer film is fixed to the surface of the fibril of the hollow yarn and a crosslinked structure is introduced between molecular chains of polyethylene. As a result, good hydrophilic capacity can be imparted to the surface of the fibril of the hollow yarn and the collapse or heat shrinkage of the yarn due to softening when hot water is filtered can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a porous polyolefin hollow fiber having excellent heat resistance and hydrophilicity.

[Conventional technology]

Conventionally, a wide variety of devices have been proposed as pure water production devices used in fields such as medical, pharmaceutical, food industry, precision industry, and physical and chemical experiments. That is,
These include pure water production equipment that does not contain colloidal substances or bacteria, and furthermore, pure water production equipment that does not contain pyrogenic substances.

For example, as a sterile water production device in the medical field,
There are devices that use distillation methods, boiling sterilizers, and ultraviolet sterilizers, but they require high energy and equipment costs, and some sterilize them insufficiently.Also, although they can remove colloidal substances and bacteria, they cannot remove pyrogenic substances. Some devices have drawbacks such as the inability to remove (pyrogene).

Under these circumstances, in order to solve the drawbacks of conventional devices, the applicant has developed a device with a pore diameter of 0.0 that can remove exothermic substances, etc.
We have proposed a porous polyolefin hollow fiber having fibrils in which micropores of 1 to 1 μm are connected from the inner wall surface of the hollow fiber to the outer wall surface (see JP-A-57-42919).

[Problem that the invention seeks to solve]

As mentioned above, modules using porous polyolefin hollow systems have various advantages, but because they are hydrophobic, sufficient filtration cannot be achieved unless they are hydrophilized using a hydrophilic agent such as alcohol. In addition, after water has been filtered for a long time, if the water is removed to clean the module and the surface of the porous polyolefin hollow fibers is dried by contacting with air, there is a problem that the freeness is significantly reduced. be.

Furthermore, when hot water is filtered, the threads shrink significantly or become crushed due to softening, resulting in a decrease in freeness. Therefore, an object of the present invention is to provide a porous polyolefin hollow fiber having excellent heat resistance and hydrophilicity.

[Means for solving problems]

The present invention provides a porous polyolefin hollow fiber in which micropores formed between a large number of fibrils arranged substantially in the longitudinal direction of the hollow fiber communicate between the inner wall surface and the outer wall surface of the hollow fiber. The porous polyolefin hollow fiber has 5 to 95% by weight of an alkoxy(meth)acrylic acid polyethylene glycol compound and 5 to 95% by weight of a double polymer copolymerizable with the compound on the surface of the fibril. It is characterized in that a mixture of at least two kinds of compounds containing a monomer having at least two or more bonds is polymerized and fixed by radiation to make it heat-resistant and hydrophilic.

If the amount of alkoxypolyethylene glycol (meth)acrylate exceeds 95% by weight, the film formation properties will be poor and the physical durability will also be reduced. In addition, if it is less than 5% by weight,
Hydrophilicity becomes insufficient and water flux becomes low.

The porous polyolefin hollow fiber used in the present invention, in which micropores communicate from the inner wall surface to the outer wall surface of the hollow fiber, can be obtained by the manufacturing method previously disclosed in JP-A-57-42919.

In addition, the components that form the polymer film that adheres to the fibril surface of the porous polyolefin hollow fibers include:
Contains the following compounds:

That is, examples of the first component include a compound represented by the following formula (A).

(In the formula, n is 10 to 100, R is an alkyl group having 12 or more carbon atoms, and R' is hydrogen or a methyl group)
.

In this case, the degree of polymerization n of the polyethylene glycol chain is 10
It is preferable that it be in the range of 100 to 100. This is because if n is less than 10, the parent wood performance will not be sufficient, and if n is more than 100, the viscosity will increase and the micropores in the porous layer will be blocked, leading to a decrease in flux. The number is preferably 12 or more in order to obtain affinity with polyolefins. Although the above compound exhibits good hydrophilic performance even when used alone, it has poor film-forming properties, so it can be used in an amount of 5 to 95% by weight.
A second component that improves film forming properties is added.

As the second component, a monomer having at least two or more double bonds that can be copolymerized with the first component is used, such as ethylene glycol dimethacrylate, allyl methacrylate, 2-methacryoxyethylmaleic acid, dimethacrylate, etc. Examples include 1,3-butylene glycol methacrylate, trimethylolpropane trimethacrylate, and pentaerythritol tetramethacrylate. This second component is 2 to 95
By adding % by weight, the film forming ability is significantly improved, and a uniform polymer film can be obtained by radiation without impairing the parent wood performance.

As a method for polymerizing and fixing the above compound to the fibril surface of the porous polyolefin hollow fiber, the porous polyolefin is added to a solution in which at least two or more of the above compounds are dissolved in a solvent that easily wets the polyolefin, such as methanol. After the hollow fibers are immersed, the medium is removed (by air drying, etc.) and radiation polymerization is performed. In this case, examples of the radiation used include electron beams, ultraviolet rays, plasma, etc., but in order to improve heat resistance, it is preferable to use electron beams, which can simultaneously perform a crosslinking reaction between molecules of the polyolefin.

By performing the above treatment, it becomes possible to impart good hydrophilic properties to the fibril surface of the porous polyolefin hollow fiber. In addition, the fixed polymer coating is a highly crosslinked and heat resistant coating, and a crosslinked structure is also introduced inside the hollow fibers, so the fibers will not collapse due to softening when hot water is filtered. It becomes possible to suppress thermal contraction.

〔Example〕

The present invention will be explained in detail below with reference to Examples.

Example 1 Porous polyethylene hollow fiber EHF (trade name, manufactured by Mitsubishi Rayon Co., Ltd.) was mixed with 5 parts by weight of an alkoxy polyethylene glycol acrylate compound (in formula A, n-30, carbon number of R: 12) and tetraethylene diacrylate. 20 by dissolving 5 parts by weight of glycol in 90 parts by weight of methanol
After being immersed in the solution at 0.degree. C. for 30 seconds, it was air-dried for 10 minutes to remove methanol.

Subsequently, using an electron beam irradiation device (Nissin t\Ivoltage, Curetron EBC-200-20-15),
An electron beam was irradiated at a dose of Mrad to fix a polymer film to the surface of the laminated structure of porous polyethylene hollow fibers and introduce a crosslinked structure between the molecular chains of the polyethylene.

Next, the above heat-resistant and hydrophilized porous polyethylene hollow fiber 10
Bundle the fibers into a U-shape, harden the opening of the hollow fibers with resin,
A module with a resin-embedded portion having a length of 4 cm and a hollow fiber effective length of 10 cm was produced.

As a reference example, a normal module was produced in the same manner as above using the porous polyethylene hollow fibers that had not been subjected to the heat-resistant hydrophilic treatment.

As a result of measuring the water permeability pressure and water permeability of the above heat-resistant hydrophilic porous polyethylene hollow fiber module, it was 0.05 kg.
Water filtration begins at a low pressure of r/cal, and the water permeation rate at a water pressure of 1 kg f/crA is 13 per minute.
It was cc/cat.

On the other hand, a module using porous polyethylene hollow fibers that was not heat-resistant and hydrophilized was prepared as a reference example.
The permeability pressure is extremely high, with a pressure of 3 kgf/c [l! The water was not filtered at all even after adding . Furthermore, 80°C hot water was poured into the module using heat-resistant, hydrophilized porous polyethylene hollow fibers at a pressure of 1 kgf/cot.
After filtration for an hour, remove the hot water and put it in a vacuum dryer for 60 minutes.
After drying at ℃ for 24 hours, the water permeation pressure and water permeation amount were measured again, and no deterioration in performance was observed even though the hot water was filtered and dried.

Example 2 Porous polyethylene hollow fiber E HF was treated with an acrylic acid alkoxypolyethylene glycol compound (in formula A,
3 parts by weight of n-30, R having 12 carbon atoms and 2 parts by weight of trimethylolpropane trimethacrylate were mixed with 95 parts by weight of methanol.
After being immersed in a 20° C. solution containing parts by weight for 10 seconds, it was air-dried for 10 minutes to remove methanol. Subsequently, the fibers were irradiated with an electron beam at a dose of 10 AD to obtain heat-resistant, hydrophilic porous polyethylene hollow fibers.

Next, a module similar to that in Example 1 was fabricated using the heat-resistant, hydrophilized porous polyethylene hollow fibers described above, and the water permeation pressure and water permeation amount were measured. The water permeation rate was 11 cc/crA per minute at a water pressure of 1 kgf/cd.

Further, no deterioration in performance was observed even after hot water filtration and drying at 80°C.

[Effects and operations of the invention]

At least two or more types containing an alkoxypolyethylene glycol (meth)acrylate compound and a monomer having at least two or more double bonds copolymerizable with the alkoxypolyethylene glycol (meth)acrylate compound on the fibril surface of the porous polyolefin hollow fiber having hydrophobicity. By polymerizing and fixing a mixture of compounds using radiation, it is possible to impart heat resistance and hydrophilicity at the same time, and not only can the conventional pretreatment such as alcohol immersion be omitted, but also the filtration of hot water is possible. It is possible.

Claims (1)

[Claims] A porous polyolefin hollow fiber in which micropores formed between a large number of fibrils arranged substantially in the longitudinal direction of the hollow fiber communicate between the inner wall surface and the outer wall surface of the hollow fiber. It is a thread, and the surface of the fibril contains 5 to 95% by weight of a compound represented by formula (A) and 5 to 95% by weight of at least two double bonds that are copolymerizable with the compound of formula (A). 1. A heat-resistant, hydrophilized porous polyolefin hollow fiber, characterized in that a mixture of at least two or more compounds, including a monomer having the above-mentioned properties, is polymerized and fixed by radiation. (A) Formula: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the above formula, n is 10 to 100, R is an alkyl group having 12 or more carbon atoms, and R' is hydrogen or a methyl group) .