JPS63225636A - Microporous polyphenylene sulfone molding - Google Patents

Abstract

PURPOSE:To obtain the title molding excellent in heat resistance, chemical resistance and mechanical strengths and suitable for a filter for purifying concn. sulfuric acid, conc. nitric acid or the like, by oxidizing a microporous molding comprising polyphenylene sulfide with an organic peroxide. CONSTITUTION:A microporous molding comprising polyphenylene sulfide having continuous micropores of a porosity of 10-90% and a specific surface area >=0.4m<2>/g is formed from a polyphenylene sulfide such as poly-p-phenylene sulfide obtained by reacting, for example, an alkali sulfide with a p- dihalobenzene at a high temperature and a high pressure in a high-boiling polar solvent of an maide type such as N-methyl-pyrrolidone by a wet coagulation process. This molding is oxidized by immersion in an organic peracid such as peracetic acid to obtain the title molding formed from a resin mainly consisting of structural units of formula I (wherein X is 0-2) and having a ratio of structural units of formula II (wherein Y is 1 or 2) to structural units of formula I >=0.3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a microporous polyphenylene sulfone molded product that has excellent heat resistance and chemical resistance.

[Conventional technology]

Microporous molded products such as microporous films and microporous membranes have traditionally been used in seawater desalination, pure water production for the electronics industry, sewage treatment in the paper industry and pulp mills, recovery of electrolytic coating fluids, oil and
It has been used in a variety of fields, including pollution-related industrial water recovery and waste liquid treatment such as water emulsion separation, medical-related filtration materials such as artificial kidneys for plasma separation, and even as separators for various batteries. There is.

In recent years, as membrane separation processes using such microporous molded products have become widespread, there has been an increasing demand for microporous molded products that have excellent mechanical strength even at higher temperatures and in a wide pHTiI range.

In response to such demands, fluororesins containing fluorine atoms,
For example, since fluoroethylene, polyvinylidene fluoride, and the like have extremely excellent chemical resistance, heat resistance, weather resistance, etc., microporous molded products using such resins have been proposed. However, such resins have low mechanical strength, and although they have extremely excellent properties, they have the disadvantage that their range of application is severely limited depending on the application.

Therefore, in order to obtain a microporous molded product having sufficient mechanical strength and excellent heat resistance and chemical resistance, the following (I) and (I)
Various separation membranes using polymers consisting of structural units having an ether bond in the main chain, such as aromatic polysulfones represented by formulas I) and (III), have been proposed (Japanese Patent Application Laid-Open No. 1983-1999).
14376, Special Publication No. 61-30803, etc.)
.

However, so-called polyether sulfone having an ether bond in its main chain generally does not have a melting point, so it has been dissolved in an amide-based organic solvent or the like and formed into a separation membrane or the like by a wet method. For this reason, as a matter of course, there is a drawback that it dissolves in such amide-based organic solvents and cannot be applied in such organic solvents.

Since such polymers have a melting point of 500° C. or more and there is no solvent in which they can be dissolved, it has been virtually impossible to mold or process them into useful molded bodies.

On the other hand, in recent years, polyphenylene sulfide, especially polyparaphenylene sulfide (hereinafter abbreviated as PPS), is a polymer having sulfur atoms in the main chain, similar to polysulfone, and as a thermoplastic polymer, it has excellent heat resistance, electrical insulation, and chemical resistance. Such PPs have properties such as
JP-A-58-677 as a microporous molded product for separation using
33, JP-A-60-202659, JP-A-60-203268, etc. have been proposed.

However, even in such polyphenylene sulfide, the strength decreases significantly at high temperatures of 200 to 250°C.
It was difficult to withstand use at such high temperatures. In addition, concentrated sulfuric acid and concentrated nitric acid have problems such as partial dissolution and decomposition, and cannot be applied to filters for purifying concentrated sulfuric acid and concentrated nitric acid, which are in increasing demand in the semiconductor manufacturing field.

Therefore, its scope of development is extremely limited.
No material has yet been found that has excellent moldability, sufficient mechanical strength, and highly satisfies both heat resistance and chemical resistance.

[Problem that the invention seeks to solve]

The purpose of the present invention is to provide polyphenylene sulfone polymers with sufficient mechanical strength and excellent chemical resistance even to concentrated sulfuric acid and concentrated nitric acid without impairing the extremely excellent heat resistance inherent in the polyphenylene sulfone polymer. An object of the present invention is to provide a novel microporous polyphenylene sulfone molded product having the following properties.

[Means for solving problems]

The present inventors discovered that by modifying 1 or 2) which achieves the object of the present invention, a microporous molded product with significantly improved heat resistance and even chemical resistance can be obtained. This led to the invention.

That is, the present invention has the following configuration.

or 11 or 2) is formed from a resin having a main to structural unit ratio of 0.3 or more, and has substantially continuous micropores with a porosity of 10 to 90%, A microporous polyphenylene sulfone molded product having a specific surface area of 0.4 cd/g or more.

A polyphenylene sulfone microporous molded article according to claim (1).

Hereinafter, nine aspects of the present invention will be described in detail.

Polyphenylene sulfone of the present invention (hereinafter referred to as PPs or 2)
It refers to a microporous molded product mainly composed of polyphenylene sulfone chains composed mainly of the structural units shown in the formula (Y=1 or 2) with a structural unit ratio of 0.3 or more.

If the structural unit ratio (hereinafter referred to as ppso ratio) of 2) is less than 0.3, extremely excellent heat resistance cannot be obtained. The PP5O conversion rate is at least 0.3, preferably 0.
．． It is desirable that it be 5 or more, more preferably 0.7 or more.

(B) The ratio is preferably 1.0 or more, more preferably 2.0.
0 or more is desirable. It is particularly preferable if it is 3 or more. In particular, the ppso conversion rate is 0.9 or more, and (A)/(B)≧3
Almost all polysulfonated products have super heat resistance, so
Particularly preferred.

Here, the main chains having such a structure may be partially bonded to each other by oxygen atoms or the like to form a so-called three-dimensional structure.

Further, the bond between the benzene ring and the sulfur atom in the above structural unit formula shown in the general formula may be a loose bond or a meta bond, but a loose bond is more preferable because it provides high crystallinity.

Further, a hydroxyl group, an oxygen atom, etc. may be partially added to the benzene ring in the above structural unit formula.

Moreover, the main component as used in the present invention means containing at least 90 mol% or more of the above-mentioned structural units. If the content of the main component is less than 90 mol%, the crystallinity of the obtained polymer will decrease, the transition temperature will decrease, and it will be difficult to obtain the microporous molded product of the present invention having excellent heat resistance and chemical resistance. . On the other hand, other structural units of less than 10 mol % in the 90 mol % polyphenylene sulfide may include ether bonds, biphenyl bonds, naphthyl bonds, substituted phenylsino, lephid bonds, and the like.

Now, the polyphenylene sulfone microporous molded product of the present invention is preferably a microporous molded product having substantially continuous micropores with a porosity of 10 to 90% and a specific surface area of 0.4 nf/g or more. .

The pore diameter of the microporous material varies depending on the purpose of use of the microporous molded product, but is, for example, 0.001 to 0.0.
The ultrafiltration membrane area of 5μ can be used as a filtration membrane for sewage treatment in paper mills and pulp factories, or as an oil-resistant membrane used in the production of edible oils such as soybean oil.
In the field of microfiltration membranes, it can be used for plasma separation, as a separator for various batteries, and as a purification filter for concentrated sulfuric acid, concentrated nitric acid, etc. In addition, when the pore size is slightly larger than 5 μm, it can be used as a heat-resistant heat insulating material, and the pore size can be arbitrarily selected depending on the purpose of use and is not particularly limited. Further, the term "substantially continuous microporous" does not mean that all the micropores are continuous, and the molded article has at least IXIO'cc/cla/s.
This means that it has an air permeability of ee.

On the other hand, the porosity is preferably in the range of 10 to 90%. When the porosity is less than 10%, the filtration area is small;
Pressure loss becomes too large. On the other hand, if it exceeds 90%, the mechanical strength will be low and the applications will be limited.In addition, the specific surface area is desirably 0.4 m/g or more, more preferably 1.5 rrr/g or more. Specific surface area is 0.4
If it is less than n(/g, the filtration area is small, clogging occurs quickly, and it cannot withstand long-term use. Here, the specific surface area means the surface area of the microporous molded product per 1μ of the molded product. The so-called BET (Brunauer-Emm
It can be measured by the e t-Te 11 e r) method.

In addition, the porosity can be determined from the apparent density and true density of the microporous molded material, porosity = (1 - apparent density/true density) x 100
It can be found in (%).

The microporous molded article referred to in the present invention is a film-like flat membrane, a tube-like body, a nonwoven thermocompressed body, a sponge-like body,
This includes forms such as granules, and the shape of the microporous molded product can be arbitrarily selected depending on the purpose of use, and is not limited to these.

Next, the method for manufacturing the ppso microporous molded product of the present invention will be explained below.

The ppso microporous molded product of the present invention can basically be obtained by oxidizing a microporous molded product made of polyphenylene sulfide using an organic peracid.

First, as a method for producing polyphenylene sulfide, for example, as a method for producing polyparaphenylene sulfide (PPS), which is a particularly preferred application example of such polyphenylene sulfide, an alkali sulfide and para-dihalogenated benzene are polarized. It can be obtained by reacting in an organic solvent at high temperature and high pressure. In particular, sodium sulfide and paradichlorobenzene,
It is preferable to carry out the reaction in an amide-based high boiling point polar solvent such as N-methyl-pyrrolidone.

Next, using the polyphenylene sulfide, a microporous molded product having substantially continuous micropores with a porosity of 10 to 90% and a specific surface area of 0.4 nf/g or more is formed. Regarding the manufacturing method of such microporous molded products, wet method (
Alternatively, a wet/dry coagulation method, another component elution method, a film stretching method, a solvent evaporation method, a nonwoven fabric thermocompression bonding method, etc. can be applied, but the method is not limited to these methods.

Thereafter, the present invention is achieved by modifying the thus obtained microporous polyphenylene sulfide molded product as described in 2) with an organic peracid (hereinafter referred to as ppso conversion).

If the ppso conversion rate is less than 30 mol %, only the surface layer of the microporous molded article is converted into ppso. At this level, a significant improvement in heat resistance and chemical resistance cannot be expected. Therefore, the ppso conversion rate is desirably at least 30 mol% or more, preferably 50 mol% or more, and more preferably 70 mol% or more, and the larger the specific surface area of the microporous molded product, the easier it is to obtain a high PP5O product. When converting to ppso,
There is no problem in the present invention even if the main chains are bonded by oxygen atoms or the like and so-called three-dimensional crosslinking occurs due to the organic peracid.

In addition, the conversion to PP5o improves not only heat resistance and chemical resistance but also hydrophilicity, making it suitable for separators for various batteries.

Examples of the organic peracids used in the present invention include performic acid, peracetic acid, perbenzoic acid, perpropionic acid, perbutyric acid, m-chlorobenzoic acid, pertrichloroacetic acid, pertrifluoroacetic acid, and phthalic acid. . Among these, peracetic acid is preferred because of its high reaction rate and ease of handling.

Such organic peracids can be prepared by catalytic oxidation of aldehydes (e.g. AMP of peracetic acid) or gas phase partial oxidation (vapor phase), or from hydrogen peroxide and anhydrides or chlorides of carboxylic acids. It can be produced by the synthesis of sialoyl peroxide and sodium methoxide, etc.

pp of polyphenylene sulfide by such organic peracid.
The modification to so is achieved by immersing the microporous molded polyphenylene sulfide in an organic peracid, but the treatment conditions depend on the porosity and specific surface area of the microporous molded product, or the Although it varies depending on the reaction rate of peracid and cannot be absolutely limited, when peracetic acid is used, a high ppso conversion rate can be achieved even at room temperature. In addition, such organic peracids are explosive chemicals and are likely to explode, especially at high temperatures.From this point of view, microporous molded products with a large specific surface area that can easily achieve a high sulfonation rate at low temperatures are preferable. .

Examples will be described below, but the present invention is not limited to these examples.

〔Example〕

Example 1 At 300℃ manufactured by Toshi Phillips Petroleum Co., Ltd., the viscosity is 4000 voise, 7g, 90℃, Tm 28
50 parts by weight of pps fine powder having a temperature of 0°C and 50 parts by weight of trimellitic acid copolymerized polyethylene terephthalate fine powder were supplied to an extruder, mixed and melted at 310°C,
An unstretched sheet with a width of 150 μm and a thickness of 400 μm was obtained by extrusion from a T-die having a linear lip length of 200 mm and a gap of 1.0 m. This sheet was simultaneously biaxially stretched to 3.0 times in length and width at 95°C using a film stretcher, and then subjected to tension heat treatment for 1 minute at 220°C using a hot air oven to form a film with a thickness of 40μ. A sample was obtained.

Next, trimellitic acid copolymerized polyethylene terephthalate was decomposed and removed using 30% sodium hydroxide,
A microporous film with a porosity of 50% and a specific surface area of 22 d/g was obtained.

Thereafter, the microporous film was soaked in a commercially available peracetic acid solution (
After being treated in acetic acid (9% concentration product) at room temperature (30°C) for 3 hours, it was washed with water, neutralized, washed with water, and dried.

The obtained microporous film was subjected to NMR and ESCA (Ele
ctron 5pectroscopy for C
(chemical analysis) Such a microporous film does not undergo any form change when exposed to strong acids such as concentrated nitric acid, concentrated sulfuric acid, and concentrated hydrochloric acid, 30% ammonia aqueous solution, and various organic solvents including amide organic solvents. 300
2 by hanging a load of 40% of the breaking strength under a high temperature of ℃.
Even after being left for 4 hours, neither creep nor breakage was observed, and a significant improvement in heat resistance was confirmed.

Example 2 20 parts by weight of PPS resin with an apparent viscosity of 4500 poise at 300°C manufactured by Toshi-Philips Petroleum, 53 parts by weight of N-methyl-2-pyrrolidone, and 27 parts by weight of diethylene glycol were added. The mixture was dissolved under pressure at 245° C. to prepare a membrane-forming solution.

This solution was poured into a 0.5 vs. slit-like nozzle,
Water was allowed to flow out from both sides of the mouthpiece slit, extruded into water, and solidified to obtain a microporous membrane with a porosity of 25% and a specific surface area of 5 rrr/g.

This microporous membrane was then treated in a 9% peracetic acid solution at room temperature for 1 hour, followed by washing with water, neutralization, washing with water, and drying. When the obtained microporous membrane was analyzed by ESCA, p
The pso conversion rate was 78%.

When this microporous membrane was left in air at a temperature of 300° C. for one day, almost no coloration was observed, and the strength retention rate after high-temperature treatment was extremely high at 85%.

Example 3 Using the same PPS as in Example 1, melt extrusion was performed through a slit die with a die temperature of 310°C to obtain a product with a width of 1501 m and a thickness of 2.
An unstretched film of 00μ was obtained. After performing tension heat treatment on the film at 240°C for 2 minutes using a hot air oven,
Using a film stretcher, simultaneously biaxially stretched to 1.8 times in length and width at a temperature of 265°C to obtain a porosity of 30%.
A microporous film with a specific surface area of 15 nf/g was obtained.

The microporous film was treated with 9% peracetic acid for 1 hour, then washed with water, neutralized, washed with water, and dried.

The obtained microporous film has a ppso conversion rate of 85%, does not decompose even in 69% high concentration nitric acid with a specific gravity of 1.42, and has a strength retention rate of 90% after treatment at 300°C for 24 hours.
%, chemical resistance, and heat resistance were significantly improved.

Comparative Example 1 In place of the 9% peracetic acid treatment in Example 3, 10% sodium hypochlorite was used, and after treatment at 90°C for 1 hour, an attempt was made to perform the same treatment as in Example 3. It had become brittle and crumbled from the treatment.

Comparative Example 2 The PPS microporous film of Example 2 before sulfonation was
Three-dimensional crosslinking was performed by heat treatment at 0° C. for 4 hours and air oxidation. Comparative Example 2 was heated at 300°C as in Example 2.
When treated for 24 hours, the film melted and no longer retained its film form.

〔Effect of the invention〕

However, it has excellent heat resistance and chemical resistance.

For this reason, the demand for purification filters such as concentrated sulfuric acid and concentrated nitric acid has been increasing in recent years, various filters for desulfurization and denitrification smoke gas equipment, battery separators, and recovery of electrolytic coating liquids. It can be preferably applied to filters, separation membranes, etc. in fields where chemical properties are required.

Claims (2)

[Claims] (1) General formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (Here, X = 0, 1, or 2) Mainly consists of the structural unit and occupies the structural unit ▲ Numerical formula, chemical formula, table, etc. etc. ▼ (However, Y = 1 or 2) is formed from a resin with a structural unit ratio of 0.3 or more, and
A polyphenylene sulfone microporous molded article having substantially continuous micropores with a porosity of 10 to 90% and a specific surface area of 0.4 m^2/g or more. (2) The polyphenylene sulfone microporous molded product according to claim (1), wherein the structural unit ratio of ▲ with mathematical formulas, chemical formulas, tables, etc. is 0.5 or more.