KR102447053B1 - A method for purifying a liquid, and a method for manufacturing a porous membrane - Google Patents

Abstract

To provide a method for purifying a viscous liquid capable of favorably reducing the number of bubbles in the viscous liquid, and a method for producing a porous membrane preferably used as a filter in the purification method.
A varnish containing a resin component (A), particles (B), and a solvent (S) is applied on a substrate to form a composite film comprising the resin component (A) and particles (B), and particles in the composite film Using a filter comprising a porous membrane obtained by a manufacturing method comprising removing (B), or a porous membrane having communication holes including a structure in which spherical or substantially spherical pores communicated with each other, the viscosity is 0.1 Pa ㆍFiltrate viscous liquids above s.

Description

A method for purifying a liquid, and a method for manufacturing a porous membrane

The present invention relates to a liquid purification method for purifying a viscous liquid, and a method for producing a porous membrane that can be suitably used in the purification method.

Conventionally, various viscous liquids having a certain degree of viscosity have been used for various applications. When such a viscous liquid comes into contact with gas by stirring or moving inside a pipe, it is easy to draw in gas to the inside.

When the viscous liquid draws in the gas, it is difficult to naturally degas due to the viscosity in the viscous liquid, and bubbles are stably present.

For example, when the viscous liquid is a photoresist composition, air bubbles contained in the photoresist composition cause coating unevenness or become defects in a patterned film formed using the photoresist composition.

For this reason, a method for satisfactorily removing air bubbles in a viscous liquid such as a photoresist composition is desired.

As a method of removing bubbles from a viscous liquid such as a photoresist composition, a method of supplying the viscous liquid to a substrate after passing the viscous liquid through a filter for removing foreign substances and bubbles has been proposed (Patent Document 1).

Japanese Patent Application Laid-Open No. 2010-135535

However, Patent Document 1 does not specifically describe a filter, such as a material, a shape, an opening diameter, or the like. For example, when a well-known filter such as a nonwoven fabric made of PTFE (polytetrafluoroethylene) fibers is applied to the removal of air bubbles, depending on the viscosity of the liquid and the method of passing the liquid through the filter, rather the air bubbles in the liquid to be treated may increase.

The present invention has been made in view of the above problems, and provides a method for purifying a viscous liquid capable of reducing the number of bubbles in the viscous liquid favorably, and a method for producing a porous membrane preferably used as a filter in the purification method aim to

The present inventors apply a varnish containing a resin component (A), particles (B), and a solvent (S) on a substrate to form a composite film comprising the resin component (A) and particles (B); Using a filter comprising a porous membrane obtained by a manufacturing method comprising removing the particles (B) in the composite membrane, or a porous membrane having a communicating hole including a structure in which spherical or substantially spherical pores communicate with each other, By filtering the viscous liquid having a viscosity of 0.1 Pa·s or more, it was found that the above problems could be solved, and the present invention was completed. Specifically, the present invention provides the following.

A first aspect of the present invention is a method for purifying a liquid, comprising filtering a viscous liquid having a viscosity of 0.1 Pa·s or more by means of a filter,

filter,

Applying a varnish containing a resin component (A), particles (B), and a solvent (S) on a substrate to form a composite film comprising the resin component (A) and particles (B);

It is a method containing the porous membrane obtained by the manufacturing method which includes removing the particle|grains (B) in a composite membrane.

A second aspect of the present invention is a method for purifying a liquid comprising filtering a viscous liquid having a viscosity of 0.1 Pa·s or more by means of a filter,

filter,

It is a method containing a porous membrane having a communicating hole including a structure in which spherical pores or substantially spherical pores communicate with each other.

A third aspect of the present invention is

Applying a varnish containing a resin component (A), particles (B), and a solvent (S) on a substrate to form a composite film comprising the resin component (A) and particles (B);

A method for producing a porous membrane comprising removing particles (B) in the composite membrane, the method comprising:

The viscosity of the varnish is a method of 2.0 Pa·s or more.

ADVANTAGE OF THE INVENTION According to this invention, the purification method of a viscous liquid which can reduce favorably the number of bubbles in a viscous liquid, and the manufacturing method of the porous membrane preferably used as a filter in the said purification method can be provided.

«First purification method»

In the present specification, the liquid purification method described below is referred to as a “first purification method”.

Specifically, a method for purifying a liquid comprising filtering a viscous liquid having a viscosity of 0.1 Pa·s or more with a filter, comprising:

filter,

Applying a varnish containing a resin component (A), particles (B), and a solvent (S) on a substrate to form a composite film comprising the resin component (A) and particles (B);

It is a method containing the porous membrane obtained by the manufacturing method including removing the particle|grains (B) in a composite membrane.

In addition, the viscosity of a viscous liquid is a value measured at 25 degreeC using an E-type viscometer.

In the first purification method, by using a filter including a porous membrane obtained through the predetermined step, a viscous liquid having a predetermined viscosity can be filtered and purified while reducing the number of bubbles contained in the viscous liquid.

The porous membrane used by the 1st purification method is equipped with the void|hole corresponding to the shape of particle|grains (B). And in a porous membrane, it originates in the manufacturing method of a porous membrane, and the communication hole by which many cavities communicate with each other is formed.

In a porous membrane having such a communication hole, the opening on the front surface (first main surface) of the porous film and the opening on the back surface (the second main surface opposite to the first main surface) of the porous film are the communication holes. communicated by

This communication hole functions as a flow path through which the fluid flows from the first main surface to the second main surface of the porous film when the porous film is used as a filter.

Although the reason is not clear, the inclusion of communication holes of a characteristic shape in the porous membrane prevents the passage of bubbles from passing through the porous membrane, the generation of bubbles when the viscous liquid passes through the porous membrane, and gas dissolved in the viscous liquid. It is considered that the number of bubbles contained in the viscous liquid is reduced by filtration of the viscous liquid using the porous membrane as a filter, as a result of which the growth of the viscous liquid is inhibited.

Moreover, of course, a porous membrane is also equipped with the function which removes a solid fine foreign material. For this reason, according to the 1st purification method, not only the number of bubbles in a viscous liquid but also the number of solid foreign substances is reduced.

It is preferable that the porous membrane used as a filter has a communicating hole containing the structure in which the spherical hole or substantially spherical hole communicated with each other.

That is, it is preferable that substantially all substantially all of the hole in the porous membrane in this invention have a curved surface at least on the inner surface. In the present specification, as such a hole, a hole having a shape substantially close to a true sphere may be described as a "spherical hole", and a hole having a shape substantially close to a true sphere may be described as a "substantially spherical hole".

In the present specification, the term "approximately spherical" is defined by the sphericity degree represented by the value obtained by dividing the major axis of spherical particles or pores by the minor axis.

The sphericity is within 1 ± 0.3, and the shape that is not a true sphere is roughly spherical. 0.90 or more and 1.10 or less are preferable and, as for the sphericity of the spherical hole or substantially spherical hole contained in the porous membrane used by the 1st purification method, 0.95 or more and 1.05 or less are more preferable.

From the viewpoint of easy filtration in a short time, the Gurley air permeability of the porous membrane is, for example, preferably within 1000 seconds, more preferably within 100 seconds, still more preferably within 50 seconds, and most preferably within 20 seconds. . Although the lower limit is not particularly set because it is preferable to be lower, the number of bubbles is easily reduced while maintaining the flow rate of the viscous liquid passing through the porous membrane to a certain extent, for example, 1 second or longer is preferred.

<The manufacturing method of a porous membrane>

The porous membrane used as a filter in the first purification method,

Applying a varnish containing a resin component (A), particles (B), and a solvent (S) on a substrate to form a composite film comprising the resin component (A) and particles (B);

It is manufactured by the method containing the porous membrane obtained by the manufacturing method including removing the particle|grains (B) in a composite membrane.

Hereinafter, the process of forming a composite film is also described as a "composite film forming process", and the process of removing the particles (B) from the composite film is also described as a "removal process".

[Composite film formation process]

In the composite film formation step, a varnish containing a resin component (A), particles (B), and a solvent (S) is applied on a substrate to form a coating film, and then the solvent (S) is removed from the coating film A composite film composed of the resin component (A) and the particles (B) is formed.

Hereinafter, the component contained in a varnish, the manufacturing method of a varnish, and an application|coating method are demonstrated.

[Resin Component (A)]

The resin component (A) is not particularly limited as long as it is a resin having sufficient mechanical strength and chemical resistance to be used as a filter.

As the resin preferably used as the resin component (A), at least one resin selected from the group consisting of polyvinylidene fluoride, polyethersulfone, polyamic acid, polyimide, polyamideimide precursor, and polyamideimide. includes

In addition, when the resin component (A) contains polyamic acid or a polyamideimide precursor, imidization is performed on the composite film or on the porous film after removing the particles (B), and polyamic acid , or the polyamideimide precursor is preferably converted into polyimide or polyamideimide, respectively.

Hereinafter, these resins are demonstrated.

(polyvinylidene fluoride)

As polyvinylidene fluoride, if it is soluble in the solvent used for varnish formation, it will not specifically limit. As polyvinylidene fluoride, a homopolymer may be sufficient and a copolymer (copolymer) may be sufficient as it. As a structural unit to copolymerize, ethylene, trifluoroethylene chloride, tetrafluoroethylene, or hexafluoropropylene etc. are mentioned, The mass average molecular weight is about 10,000 or more and 5 million or less, for example.

(polyethersulfone)

It will not specifically limit, if it is soluble in the solvent used for varnish formation as polyether sulfone. The polyether sulfone may be appropriately selected according to the use of the porous membrane to be manufactured, and may be hydrophilic or hydrophobic. Moreover, an aliphatic polyether sulfone may be sufficient and an aromatic polyether sulfone may be sufficient. The mass average molecular weights are, for example, 5,000 or more and 1,000,000 or less, and preferably 10,000 or more and 300,000 or less.

(polyamic acid)

As a polyamic acid, the product obtained by superposing|polymerizing arbitrary tetracarboxylic dianhydride and diamine can be used, without being specifically limited. Although the usage-amount of tetracarboxylic dianhydride and diamine is not specifically limited, It is preferable to use 0.50 mol or more and 1.50 mol or less of diamine with respect to 1 mol of tetracarboxylic dianhydride, Using 0.60 mol or more and 1.30 mol or less It is more preferable, and it is especially preferable to use 0.70 mol or more and 1.20 mol or less.

Tetracarboxylic dianhydride can be suitably selected from the tetracarboxylic dianhydride conventionally used as a synthetic|combination raw material of a polyamic acid. Although aromatic tetracarboxylic dianhydride may be sufficient as tetracarboxylic dianhydride, or aliphatic tetracarboxylic dianhydride may be sufficient as it, It is preferable to use aromatic tetracarboxylic dianhydride from the heat resistant point of the polyimide resin obtained. do. Tetracarboxylic dianhydride may be used individually by 1 type, and may be used in combination of 2 or more type.

Preferred specific examples of aromatic tetracarboxylic dianhydride include pyromellitic dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, and bis(2,3-dicarboxyphenyl)methane 2 Anhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxyl Acid dianhydride, 2,2,6,6-biphenyltetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-di Carboxyphenyl)propane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis(2,3 -dicarboxyphenyl)-1,1,1,3,3,3-hexafluoropropane dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, bis(3,4- Dicarboxyphenyl) ether dianhydride, bis(2,3-dicarboxyphenyl) ether dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 4,4-(p-phenylenedi) Oxy)diphthalic dianhydride, 4,4-(m-phenylenedioxy)diphthalic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic Acid dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxyl Acid dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrene tetracarboxylic dianhydride, 9,9-bis-phthalic anhydride fluorene, 3,3 ',4,4'-diphenylsulfonetetracarboxylic dianhydride etc. are mentioned. As aliphatic tetracarboxylic dianhydride, For example, ethylene tetracarboxylic dianhydride, butane tetracarboxylic dianhydride, cyclopentane tetracarboxylic dianhydride, cyclohexane tetracarboxylic dianhydride, 1, 2,4,5-cyclohexanetetracarboxylic dianhydride, 1,2,3,4-cyclohexanetetracarboxylic dianhydride, etc. are mentioned. In these, 3,3',4,4'- biphenyltetracarboxylic dianhydride and pyromellitic dianhydride are preferable from a price, availability, etc. Moreover, these tetracarboxylic dianhydride can also be used individually by 1 type or in mixture of 2 or more types.

The diamine can be appropriately selected from diamines conventionally used as a raw material for synthesis of polyamic acid. Although aromatic diamine or aliphatic diamine may be sufficient as diamine, the point of the heat resistance of the polyimide resin obtained to aromatic diamine is preferable. These diamines may be used individually by 1 type, and may be used in combination of 2 or more type.

Examples of the aromatic diamine include diamino compounds in which 1 or 2 or more and 10 or less phenyl groups are bonded. Specifically, phenylenediamine and its derivatives, diaminobiphenyl compound and its derivative, diaminodiphenyl compound and its derivative, diaminotriphenyl compound and its derivative, diaminonaphthalene and its derivative, aminophenylaminoindane and derivatives thereof, diaminotetraphenyl compounds and derivatives thereof, diaminohexaphenyl compounds and derivatives thereof, and cardo-type fluorenediamine derivatives.

The phenylenediamine is m-phenylenediamine and p-phenylenediamine, and the phenylenediamine derivative includes a diamine to which an alkyl group such as a methyl group or an ethyl group is bonded, for example, 2,4-diaminotoluene, 2,4 -triphenylenediamine, etc.

In the diaminobiphenyl compound, two aminophenyl groups are couple|bonded with each other. For example, 4,4'-diaminobiphenyl, 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl, etc. are mentioned.

The diaminodiphenyl compound is a compound in which two aminophenyl groups are bonded to phenyl groups via other groups. The bond is an ether bond, a sulfonyl bond, a thioether bond, an alkylene or derivative group bond, an imino bond, an azo bond, a phosphine oxide bond, an amide bond, a ureylene bond, and the like. The number of carbon atoms in the alkylene bond is about 1 or more and 6 or less. The derivative group of the alkylene group is an alkylene group substituted with one or more halogen atoms or the like.

Examples of the diaminodiphenyl compound include 3,3'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-diaminodi Phenylsulfone, 3,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4 '-Diaminodiphenylmethane, 4,4'-diaminodiphenylsulfide, 3,3'-diaminodiphenylketone, 3,4'-diaminodiphenylketone, 2,2-bis(p- Aminophenyl)propane, 2,2'-bis(p-aminophenyl)hexafluoropropane, 4-methyl-2,4-bis(p-aminophenyl)-1-pentene, 4-methyl-2,4- Bis(p-aminophenyl)-2-pentene, iminodianiline, 4-methyl-2,4-bis(p-aminophenyl)pentane, bis(p-aminophenyl)phosphine oxide, 4,4'-dia Minoazobenzene, 4,4'-diaminodiphenylurea, 4,4'-diaminodiphenylamide, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy) ) Benzene, 1,3-bis (3-aminophenoxy) benzene, 4,4'-bis (4-aminophenoxy) biphenyl, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [ 4-(3-aminophenoxy)phenyl]sulfone, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]hexa Fluoropropane etc. are mentioned.

Among these, p-phenylenediamine, m-phenylenediamine, 2,4-diamittoluene, and 4,4'-diaminodiphenyl ether are preferable from the viewpoint of price and availability.

The diaminotriphenyl compound is a compound in which two aminophenyl groups and one phenylene group are both bonded via another group. As for the other group, the same group as the diaminodiphenyl compound is selected. Examples of the diaminotriphenyl compound include 1,3-bis(m-aminophenoxy)benzene, 1,3-bis(p-aminophenoxy)benzene, 1,4-bis(p-aminophenoxy)benzene and the like.

Examples of diaminonaphthalene include 1,5-diaminonaphthalene and 2,6-diaminonaphthalene.

Examples of aminophenylaminoindane include 5 or 6-amino-1-(p-aminophenyl)-1,3,3-trimethylindane.

Examples of the diaminotetraphenyl compound include 4,4'-bis(p-aminophenoxy)biphenyl, 2,2'-bis[p-(p'-aminophenoxy)phenyl]propane, 2,2' -bis[p-(p'-aminophenoxy)biphenyl]propane, 2,2'-bis[p-(m-aminophenoxy)phenyl]benzophenone, etc. are mentioned.

Examples of the cardo-type fluorenediamine derivative include 9,9-bisanilinefluorene.

The number of carbon atoms of the aliphatic diamine is, for example, about 2 or more and 15 or less. Specific examples of the aliphatic diamine include pentamethylenediamine, hexamethylenediamine, and heptamethylenediamine.

Moreover, the compound by which the hydrogen atom of these diamine was substituted by the at least 1 sort(s) of substituent chosen from the group, such as a halogen atom, a methyl group, a methoxy group, a cyano group, and a phenyl group may be sufficient.

There is no restriction|limiting in particular in the means for manufacturing a polyamic acid, For example, well-known methods, such as the method of making an acid and a diamine component react in a solvent, can be used.

Reaction of tetracarboxylic dianhydride and diamine is normally performed in a solvent. The solvent used for reaction of tetracarboxylic dianhydride and diamine can melt|dissolve tetracarboxylic dianhydride and diamine, and if it is a solvent which does not react with tetracarboxylic dianhydride and diamine, it will not specifically limit. A solvent may be used individually by 1 type, and may be used in combination of 2 or more type.

Examples of the solvent used for the reaction of tetracarboxylic dianhydride and diamine include N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-diethylacetamide, and N,N-dimethyl nitrogen-containing polar solvents such as formamide, N,N-diethylformamide, N-methylcaprolactam, N,N,N',N'-tetramethylurea; lactone-based polar solvents such as β-propiolactone, γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, and ε-caprolactone; dimethyl sulfoxide; acetonitrile; fatty acid esters such as ethyl lactate and butyl lactate; ethers such as diethylene glycol dimethyl ether, diethylene glycol diethyl ether, dioxane, tetrahydrofuran, methyl cellosolve acetate, and ethyl cellosolve acetate; Phenolic solvents, such as cresols and a xylene-type mixed solvent, are mentioned.

These solvents may be used individually by 1 type, and may be used in combination of 2 or more type. Although there is no restriction|limiting in particular in the usage-amount of a solvent, It is preferable to make content of the polyamic acid produced|generated into 5 mass % or more and 50 mass % or less.

Among these solvents, from the solubility of the produced polyamic acid, N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylformamide, N A nitrogen-containing polar solvent such as ,N-diethylformamide, N-methylcaprolactam, or N,N,N',N'-tetramethylurea is preferable.

The polymerization temperature is generally -10°C or more and 120°C or less, and preferably 5°C or more and 30°C or less. The polymerization time differs depending on the raw material composition used. The polymerization time is usually 3 Hr (hours) or more and 24 Hr or less.

A polyamic acid may be used individually by 1 type, and may be used in combination of 2 or more type.

[Polyimide resin]

As for polyimide resin, the structure or molecular weight is not limited, A well-known polyimide resin can be used. With respect to a polyimide, you may have a functional group which accelerates|stimulates a crosslinking reaction etc. at the time of a functional group condensable, such as a carboxy group, or baking in a side chain. Moreover, when a varnish contains a solvent, the soluble polyimide resin which can melt|dissolve in the solvent to be used is preferable.

In order to make a polyimide resin soluble in a solvent, use of a monomer for introducing a flexible bending structure into the main chain, for example, ethylenediamine, hexamethylenediamine, 1,4-diaminocyclohexane, 1,3-dia aliphatic diamines such as minocyclohexane and 4,4'-diaminodicyclohexylmethane; aromatic diamines such as 2-methyl-1,4-phenylenediamine, o-tolidine, m-tolidine, 3,3'-dimethoxybenzidine, and 4,4'-diaminobenzanilide; polyoxyalkylenediamines such as polyoxyethylenediamine, polyoxypropylenediamine, and polyoxybutylenediamine; polysiloxane diamine; 2,3,3',4'-oxydiphthalic anhydride, 3,4,3',4'-oxydiphthalic anhydride, 2,2-bis(4-hydroxyphenyl)propanedibenzoate-3, Use of 3',4,4'-tetracarboxylic dianhydride etc. is effective. In addition, use of a monomer having a functional group that improves solubility in a solvent, for example, 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl, 2-trifluoromethyl- It is also effective to use a fluorinated diamine such as 1,4-phenylenediamine. Moreover, in addition to the monomer for improving the solubility of the said polyimide resin, you may use together the monomer same as the monomer described in the column of the said polyamic acid in the range which does not impair solubility.

Each of polyimide resin and its monomer may be used individually by 1 type, and may be used in combination of 2 or more type.

There is no restriction|limiting in particular in the means for manufacturing a polyimide resin. For example, a known method such as a method of chemical imidization or heat imidization of polyamic acid can be used. As such a polyimide resin, an aliphatic polyimide resin (all aliphatic polyimide resin), an aromatic polyimide resin, etc. are mentioned, An aromatic polyimide resin is preferable. As the aromatic polyimide resin, a polyimide resin obtained by subjecting a polyamic acid having a repeating unit represented by formula (1) to a ring closure reaction by heat or chemical means, or a polyimide resin having a repeating unit represented by formula (2), etc. can be heard In the formula, Ar represents an aryl group. When a varnish contains a solvent, what is necessary is just to melt|dissolve these polyimide resin in the solvent used next.

[Formula 1]

[Formula 2]

(Polyamideimide resin and polyamideimide precursor)

The polyamide-imide resin is not limited to the structure or molecular weight, and a known polyamide-imide resin can be used. With respect to polyamideimide resin, you may have in a side chain a functional group which can be condensed, such as a carboxy group, or a functional group which accelerates|stimulates a crosslinking reaction etc. at the time of baking. Moreover, when a varnish contains a solvent, the soluble polyamideimide resin which can melt|dissolve in the solvent to be used is preferable.

The polyamideimide resin is usually (i) a resin obtained by reacting a diisocyanate with an acid having a carboxyl group and an acid anhydride group in one molecule, such as trimellitic anhydride, and (ii) the reactivity of the acid such as trimellitic anhydride chloride Resin obtained by imidating the precursor polymer (polyamideimide resin precursor) obtained by reaction of a derivative and diamine, etc. can be used without limitation in particular.

As said acid or its reactive derivative, trimellitic anhydride halides, such as trimellitic anhydride and trimellitic anhydride chloride, trimellitic anhydride ester, etc. are mentioned, for example.

As said arbitrary diamine, the diamine illustrated by description of the above-mentioned polyamic acid is mentioned. Moreover, a diaminopyridine type compound can also be used.

It does not specifically limit as said arbitrary diisocyanate, For example, the diisocyanate compound corresponding to the said arbitrary diamine, etc. are mentioned, Specifically, metaphenylene diisocyanate, p-phenylene diisocyanate, o- Tolidine diisocyanate, p-phenylenediisocyanate, m-phenylenediisocyanate, 4,4'-oxybis(phenylisocyanate), 4,4'-diisocyanatediphenylmethane, bis[4-(4-isocyanatephenoxy) Phenyl]sulfone, 2,2'-bis[4-(4-isocyanatephenoxy)phenyl]propane, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate , 3,3'-dimethyldiphenyl-4,4'-diisocyanate, 3,3'-diethyldiphenyl-4,4'-diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, 4,4' -dicyclohexylmethane diisocyanate, m-xylene diisocyanate, p-xylene diisocyanate, naphthalene diisocyanate, etc. are mentioned.

As a raw material monomer for polyamideimide resin, in addition to the above, the compound described as a general formula in Unexamined-Japanese-Patent No. 63-283705 and Unexamined-Japanese-Patent No. 2-198619 can also be used. Moreover, any of thermal imidation and chemical imidation may be sufficient as the imidation in the method of said (ii). For chemical imidization, a method such as immersing an unbaked composite film formed using a varnish containing a polyamideimide precursor or the like in acetic anhydride or a mixed solvent of acetic anhydride and isoquinoline can be used. In addition, a polyamideimide precursor can also be called a polyimide precursor from a viewpoint of being a precursor before imidation.

Examples of the polyamideimide resin to be contained in the varnish include (1) a polymer obtained by reacting an acid such as trimellitic anhydride with diisocyanate as described above, and (2) a reactive derivative of the acid such as trimellitic anhydride chloride and diamine. The polymer obtained by imidating the precursor polymer obtained by reaction, etc. may be sufficient. In this specification and this claim, "polyamideimide precursor" means the polymer (precursor polymer) before imidation.

Each of polyamideimide resin and polyamideimide precursor may be used individually by 1 type, and may be used in combination of 2 or more type. Moreover, with respect to polyamideimide resin, each of the said polymer, a raw material monomer, and an oligomer may be used individually by 1 type, and may be used in combination of 2 or more type.

[Particle (B)]

The material of the particle (B) is not particularly limited, as long as it is insoluble in the solvent contained in the varnish and can be subsequently removed from the composite film composed of the resin component (A) and the particle (B), and a known material can be employed. . For example, as an inorganic material, metal oxides, such as silica (silicon dioxide), titanium oxide, alumina (Al2O3), _As an organic material, _high molecular weight olefin (polypropylene, polyethylene, etc.), polystyrene, an acrylic resin organic polymer fine particles such as (methyl methacrylate, isobutyl methacrylate, polymethyl methacrylate (PMMA), etc.), epoxy resin, cellulose, polyvinyl alcohol, polyvinyl butyral, polyester, and polyether. have.

Among the materials of the particles (B), silica such as colloidal silica is preferable as an inorganic material, and an acrylic resin, particularly PMMA, is preferable as an organic material. It is preferable to use the spherical particle|grains which consist of such a material as particle|grains (B) because it is easy to form minute holes which have a curved surface in a porous membrane in an inner surface.

Moreover, resin used as a material of particle|grains (B) may be suitably selected according to the objective from a normal linear polymer and a well-known depolymerizable polymer, for example.

A typical linear polymer is a polymer in which molecular chains of the polymer are randomly cut during thermal decomposition, and a depolymerizable polymer is a polymer in which the polymer is decomposed into monomers during thermal decomposition.

All of them can be removed from the composite film by decomposing them into monomers, low molecular weight substances, or even CO ₂ during heating.

200 degreeC or more and 320 degrees C or less are preferable, and, as for the decomposition temperature of resin used as a material of particle|grains (B), 230 degreeC or more and 260 degrees C or less are more preferable.

When the decomposition temperature is 200° C. or higher, film formation can be performed even when a high boiling point solvent is used for the varnish, and the selection of firing conditions for producing a polyimide resin or polyamideimide resin by firing is wide.

Moreover, if the decomposition temperature is 320 degrees C or less, the particle|grains (B) can be lose|disappeared from a composite film, suppressing the damage by the heat|fever of the resin component (A) in a composite film.

Among depolymerizable polymers, from the viewpoint of low thermal decomposition temperature and easy handling at the time of hole formation, homopolymers of methyl methacrylate or isobutyl methacrylate (polymethyl methacrylate or polyisobutyl methacrylate); Alternatively, a copolymer mainly composed of units derived from methyl methacrylate or isobutyl methacrylate is preferable.

It is preferable to use the particle|grains (B) with a high sphericity ratio from the point which is easy to form the hole of the preferable shape which has a curved surface in the inner surface in the porous film to be formed.

The particle size (average diameter) of the particles (B) is, for example, preferably 800 nm or more and 3500 nm or less, more preferably 900 nm or more and 3000 nm or less, and particularly preferably more than 2000 nm and 2500 nm or less.

By using the particles (B) of such a particle size, communication holes through which holes of corresponding diameters communicate with each other are formed in the porous membrane. When a porous membrane having such a communication hole is used, the viscous liquid can be filtered at a pressure that does not break the porous membrane, and bubbles in the viscous liquid can be particularly easily reduced by filtration using the porous membrane.

Moreover, the particle size distribution index (d25/75) of the particle|grains (B) should just be 1 or more and 6 or less, 1.1 or more and 5 or less are preferable, and 1.2 or more and 4 or less are more preferable. By setting the lower limit to 1.1 or more, it is possible to efficiently fill the particles (B) inside the composite membrane, and for this reason, communication holes serving as flow paths for the viscous liquid are favorably formed. Moreover, in the case of 1.6 or more, since pores of different sizes are formed in the porous membrane, the convection situation in each hole portion of the viscous fluid at the time of filtration changes in various ways. It is thought that the purification effect of a viscous liquid based on adsorption|suction by the inner wall surface of a hole increases by such a change of a convection situation.

In addition, d25 and d75 are the particle diameter values whose cumulative frequency of particle size distribution is 25% and 75%, respectively, and in this specification, d25 is the larger particle diameter side.

In the manufacturing method mentioned later, when forming a composite film as a two-layer laminated film, the particle|grains (B1) used for a 1st varnish and particle|grains (B2) used for a 2nd varnish may be same or different. .

In order to make the pores on the side in contact with the substrate more dense, it is preferable that the particle size distribution index of the particle (B1) is equal to or less than the particle size distribution index of the particle (B2).

Alternatively, the spherical ratio of the particles (B1) is preferably equal to or less than that of the particles (B2).

Moreover, it is preferable that the particle diameter (average diameter) of particle|grains (B1) is smaller than the particle diameter of particle|grains (B2), and in this case, it is easy to raise the intensity|strength of a porous membrane while making the opening ratio of the porous membrane surface high and uniform.

[Dispersant]

The varnish may further contain a dispersing agent with the particle|grains (B) for the purpose of uniform dispersion|distribution of the particle|grains (B). When the varnish contains the dispersing agent, the resin component (A) and the particles (B) can be mixed more uniformly, and further, the particles (B) can be uniformly distributed in the coating film formed using the varnish. can

As a result, it is possible to form a communication hole for efficiently communicating the front and back surfaces of the porous membrane so that a dense opening is formed on the surface of the porous membrane finally obtained and the air permeability of the porous membrane is improved.

A dispersing agent is not specifically limited, It can select suitably from well-known dispersing agents. Specific examples of the preferred dispersant include palm fatty acid salt, castor sulfated oil salt, lauryl sulfate salt, polyoxyalkylene allylphenyl ether sulfate salt, alkylbenzenesulfonic acid, alkylbenzenesulfonate, alkyldiphenyletherdisulfonate. anionic surfactants such as alkylnaphthalenesulfonate, dialkylsulfosuccinate salt, isopropyl phosphate, polyoxyethylene alkyl ether phosphate salt, and polyoxyethylene allylphenyl ether phosphate salt; cationic surfactants such as oleylamine acetate, laurylpyridinium chloride, cetylpyridinium chloride, lauryltrimethylammonium chloride, stearyltrimethylammonium chloride, behenyltrimethylammonium chloride, and didecyldimethylammonium chloride; amphoteric surfactants such as palm alkyldimethylamine oxide, fatty acid amidopropyldimethylamine oxide, alkyl polyaminoethyl glycine hydrochloride, amidobetaine type active agent, alanine type active agent, and lauryl iminodipropionic acid; Polyoxyethylene octyl ether, polyoxyethylene decyl ether, polyoxyethylene lauryl ether, polyoxyethylene lauryl amine, polyoxyethylene oleylamine, polyoxyethylene polystyryl phenyl ether, polyoxyalkylene polystyryl phenyl ether, etc. , Nonionic surfactant of polyoxyalkylene primary alkyl ether or polyoxyalkylene secondary alkyl ether, polyoxyethylene dilaurate, polyoxyethylene laurate, polyoxyethylenated castor oil, polyoxyethylenated hydrogenated castor Other polyoxyalkylene-type nonionic surfactants, such as free, sorbitan lauric acid ester, polyoxyethylene sorbitan lauric acid ester, and fatty acid diethanolamide; fatty acid alkyl esters such as octyl stearate and trimethylolpropane tridecanoate; Polyether polyols, such as polyoxyalkylene butyl ether, polyoxyalkylene oleyl ether, and trimethylol propane tris (polyoxyalkylene) ether, are mentioned. A dispersing agent is not limited to these. Moreover, the said dispersing agent can also mix and use 2 or more types.

[Solvent (S)]

The kind of solvent (S) is not specifically limited, unless a resin component (A) can be melt|dissolved and particle|grains (B) are not melt|dissolved. As an example of a solvent (S), the solvent illustrated as a solvent used for reaction of tetracarboxylic dianhydride and diamine is mentioned. A solvent (S) may be used independently and may be used in combination of 2 or more type.

When the resin component (A) is polyvinylidene fluoride, examples of the solvent include lower alkyl ketones such as methyl ethyl ketone, acetone and tetrahydrofuran, trimethyl phosphate, and the like, in addition to the nitrogen-containing polar solvent.

When the resin component (A) is polyethersulfone, examples of the solvent include diphenylsulfone, dimethylsulfone, dimethylsulfoxide, benzophenone, tetrahydrothiophene-1,1-dioxide, 1, and polar solvents such as 3-dimethyl-2-imidazolidinone.

[Other Ingredients]

Varnish, in addition to the above components, for the purpose of antistatic, flame retardant, low-temperature plasticization, imparting releasability, improving coatability, etc. You may include a component as needed suitably.

[Method for producing varnish]

As described above, the varnish contains the resin component (A), the particles (B), and the solvent (S).

The manufacturing method of the varnish will not be specifically limited if the resin component (A) is melt|dissolving in the solvent (S) and it is a method which can manufacture the varnish in which the particle|grains (B) are disperse|distributed in the solvent (S).

For example, a resin component (A) may be produced|generated by polymerizing a monomer in a solvent (S), and a resin component (A) may be dissolved in a solvent (S).

When producing the resin component (A) in the solvent (S), the polymerization reaction may be carried out in the presence of the particles (B) or in the absence of the particles (B).

As for the viscosity of a varnish, 2.0 Pa.s or more are preferable. Such a viscosity is the value measured at 25 degreeC using the E-type viscometer. When the porous membrane is formed using a varnish having a viscosity of 2.0 Pa·s or more, it is particularly easy to form a porous membrane that easily removes bubbles in the viscous liquid.

The viscosity of the varnish has some influence on the dispersed state of the particles (B) in the coating film formed using the varnish, and it is estimated that a porous membrane having a communication hole in a shape that is easy to remove bubbles is formed.

As for the viscosity of a varnish, 2.0 Pa.s or more are more preferable, and 2.3 Pa.s or more and 4.9 Pa.s or less are especially preferable. Further, the viscosity of the varnish is preferably 2.0 Pa·s or more, more preferably 2.3 Pa·s or more, particularly preferably 2.5 Pa·s or more, from the viewpoint of applicability and uniformity of the film thickness of the porous membrane to be formed. do.

The method for adjusting the viscosity of the varnish is not particularly limited, but the content of the resin component (A), the type of the resin component (A), the content of the particles (B), the particle size of the particles (B), the content of the solvent (S), and It is preferable to adjust by changing at least one kind of solvent (S).

It is preferable that the solid content concentration of a varnish is 25 mass % or more. Moreover, as for the solid content concentration of a varnish, 40 mass % or less is especially preferable.

By using the varnish with a solid content concentration of 25 mass % or more, it is easy to form the porous film which is especially easy to remove the bubble in a viscous liquid. Moreover, when the solid content concentration of a varnish is 40 mass % or less, application|coating to the board|substrate of a varnish is easy and it is easy to form a uniform porous film of a film thickness.

Moreover, as for ratio _VA :VB of volume V _A of the resin component (A) and volume V _B of particle|grains ( _B ) in a varnish, 15:85-40:60 are preferable. When the resin component (A) and the particles (B) are blended in the varnish in a ratio within this range, it is easy to disperse the particles (B) uniformly in the varnish while preventing agglomeration of the particles (B), so that the surface is uniform. It is easy to form a porous film which has an opening.

[Composite film formation method]

The varnish manufactured by the method demonstrated above is apply|coated on a board|substrate, and the coating film containing a resin component (A), particle|grains (B), and a solvent (S) is formed. By heating such a coating film and removing the solvent (S), the composite film which consists of a resin component (A) and particle|grains (B) is formed.

The heating of the coating film at the time of removing the solvent (S) is 0°C or more and 120°C or less (preferably 0°C or more and 100°C or less) under normal pressure or vacuum, more preferably 60°C or more and 95°C or less under normal pressure (furthermore) Preferably at 65°C or higher and 90°C or lower).

The coating film thickness is, for example, 1 µm or more and 500 µm or less, preferably 5 µm or more and 100 µm or less, and preferably 10 µm or more and 50 µm or less. Moreover, you may form a mold release layer on a board|substrate as needed.

Moreover, in manufacture of a composite film, you may form as arbitrary processes the immersion process with respect to the solvent containing water, the pressing process, and the drying process after the said immersion process, respectively before the calcination process mentioned later as arbitrary processes.

After apply|coating a mold release agent on a board|substrate, the said release layer can dry or bake and produce it. As the releasing agent, a known releasing agent such as ammonium alkyl phosphate salt, fluorine-based or silicone can be used without particular limitation.

When the composite film containing the resin component (A) and the particles (B) is peeled from the substrate after the solvent (S) has been removed, the mold release agent remains on the peeling surface of the composite film, although slightly.

Since this residual mold release agent may affect the wettability of the porous membrane surface and mixing of impurities, it is preferable to remove it.

In the case of forming the release layer, the composite film peeled off from the substrate is preferably washed using an organic solvent or the like. As the cleaning method, it can be selected from known methods such as a method of taking out the composite membrane after immersing it in a cleaning solution, and a method of shower cleaning by spraying the cleaning solution on the composite membrane.

In addition, the composite film after washing is dried. As the drying method, a known method can be applied without limitation, such as air drying the composite membrane after washing at room temperature, heating the composite membrane to an appropriate set temperature in a thermostat, and the like. At the time of drying, for example, a method of preventing deformation by fixing the end of the composite film to a mold made of SUS or the like may be adopted.

On the other hand, when the substrate is used as it is without forming a release layer for forming the composite film, the process of forming the release layer and the cleaning process of the unbaked composite film can be omitted.

In addition, when forming the composite film as a two-layer laminated film, first, the first varnish is applied as it is on a substrate such as a glass substrate, and 0°C or more and 120°C or less (preferably 0°C or more and 90°C or less under normal pressure or vacuum) or less), more preferably at a normal pressure of 10°C or higher and 100°C or lower (more preferably 10°C or higher and 90°C or lower) to form a first composite film. As for the film thickness of a 1st composite film, 1 micrometer or more and 5 micrometers or less are preferable.

Then, on the first composite film, a second varnish is applied, and in the same manner, 0°C or more and 80°C or less (preferably 0°C or more and 50°C or less), more preferably 10°C or more and 80°C or less at normal pressure (More preferably, it dries at 10 degreeC or more and 30 degreeC or less), a 2nd composite film is formed, and the composite film which is a two-layer laminated film is obtained. As for the film thickness of a 2nd composite film, 5 micrometers or more and 50 micrometers or less are preferable.

When the resin component (A) constitutes the porous membrane as it is, the composite membrane obtained by the above method is then subjected to a removal step described later.

In addition, when the resin component (A) contains a polyamic acid, a polyamideimide precursor, etc., if necessary, the composite film is fired before removing the fine particles (B), and the polyamide contained in the resin component (A) You may convert a mixed acid or a polyamide-imide precursor into a polyimide resin or polyamide-imide resin, respectively.

The firing temperature also varies depending on the structure of the polyamic acid or polyamideimide precursor contained in the composite film and the presence or absence of a condensing agent. As for a calcination temperature, 120 degreeC or more and 400 degrees C or less are preferable normally, More preferably, they are 150 degreeC or more and 375 degrees C or less.

Firing is not necessarily clearly separated from the drying process. For example, when calcining is performed at 375°C, the temperature is raised from room temperature to 375°C in 3 hours and then maintained at 375°C for 20 minutes, or the temperature is raised from room temperature to 375°C stepwise at 50°C intervals (each step A stepwise drying-heat imidization method such as holding for 20 minutes) and finally maintaining at 375° C. for 20 minutes may be used. In that case, a method of preventing deformation by fixing the end of the unbaked composite film to a mold made of SUS or the like may be adopted.

The thickness of the composite film can be obtained by measuring and averaging the thicknesses at multiple points with a micrometer or the like. A thinner one is preferable, for example, 1 micrometer or more should just be sufficient as average thickness, 5 micrometers or more and 500 micrometers or less are preferable, and 8 micrometers or more and 100 micrometers or less are more preferable.

[removal process]

By removing the particles (B) from the composite membrane by selecting an appropriate method, a porous membrane having fine pores can be produced with good reproducibility.

For example, when silica is employed as the fine particles, the composite membrane is treated with low-concentration hydrogen fluoride (HF) or the like to dissolve and remove silica from the composite membrane to obtain a porous membrane.

In addition, when the particle (B) is a resin fine particle, the composite film is heated to a temperature equal to or higher than the thermal decomposition temperature of the resin fine particle and lower than the thermal decomposition temperature of the resin component (A), thereby decomposing the resin fine particle and making it a composite film can be removed from

When the porous film obtained after the removal step contains polyamic acid or polyamideimide precursor as the resin component (A), treatment for ring closure of the polyamic acid or polyamideimide precursor to form an imide ring with respect to the porous film may be carried out.

As such a process, the above-mentioned baking process is mentioned.

[Chemical Etching Process]

Chemical etching may be further performed with respect to the composite film|membrane or porous film formed as mentioned above. By performing chemical etching, the aperture ratio of the porous film surface can be raised. In particular, when chemical etching is performed with respect to a porous film, the some hole originating in particle|grains (B) communicates favorably, and it is easy to form a communication hole of a preferable shape.

It does not specifically limit as a chemical etching method, For example, a conventionally well-known method can be used.

As a chemical etching method, the process by chemical etching liquids, such as an inorganic alkali solution or an organic alkali solution, is mentioned. An inorganic alkali solution is preferred. As an inorganic alkali solution, for example, a hydrazine solution containing hydrazine hydrate and ethylenediamine, a solution of alkali metal hydroxides such as potassium hydroxide, sodium hydroxide, sodium carbonate, sodium silicate, and sodium metasilicate, ammonia solution, alkali hydroxide and hydrazine and 1 Etching liquid etc. which have 3-dimethyl- 2-imidazolidinone as a main component are mentioned. As an organic alkali solution, Primary amines, such as ethylamine and n-propylamine; secondary amines such as diethylamine and di-n-butylamine; tertiary amines such as triethylamine and methyldiethylamine; alcohol amines such as dimethylethanolamine and triethanolamine; quaternary ammonium salts such as tetramethylammonium hydroxide and tetraethylammonium hydroxide; and alkaline solutions such as cyclic amines such as pyrrole and piperidine.

About the solvent of each said solution, pure water and alcohol can be selected suitably. In addition, a solvent to which an appropriate amount of a surfactant is added can also be used. Alkali concentration is 0.01 mass % or more and 20 mass % or less, for example.

When performing chemical etching, in order to remove an excess etching liquid component, it is preferable to wash|clean a porous film.

Although water washing alone may be sufficient as washing|cleaning after chemical etching, it is preferable to combine acid washing and/or water washing.

[Physical removal process]

The composite film or the porous film formed as described above may be physically removed separately from or together with the chemical etching.

As a method of physical removal, dry etching by plasma (oxygen, argon, etc.), corona discharge, etc. is mentioned.

By this method, the resin component (A) in a porous film is partially removed, and hardening similar to said chemical etching is obtained.

[Recalcination Process]

When a porous membrane is produced using a varnish containing a resin component (A) comprising at least one selected from polyimide resin, polyamideimide resin, polyamic acid, and polyamideimide precursor, the organic solvent on the surface of the porous membrane In order to improve the wettability and remove residual organic matter, once the porous membrane is obtained, the porous membrane may be fired again.

The calcination conditions in the recalcination step are the same as those for ring closure of the polyamic acid or polyamideimide precursor to form an imide ring.

By the method described above, the porous membrane used as a filter in the 1st purification method is manufactured.

The obtained porous membrane has spherical pores with an average diameter of 800 nm or more and 3500 nm or less (preferably 900 nm or more and 3000 nm or less, more preferably more than 2000 nm and 2500 nm or less). As the pore diameter of the portion (communication hole) to which the spherical pores are connected, it is preferable that 50 nm or more and 2000 nm or less of communication holes are included, more preferably 500 nm or more and 1800 nm or less, and more than 1000 nm 1300 nm It is especially preferable that the following communication holes are included. 500 nm or more and 2000 nm or less are preferable, as for the average pore diameter of the communication hole measured with a porosimeter, 900 nm or more and 1800 nm or less are more preferable, 1000 nm or more and 1500 nm or less are still more preferable. Moreover, the porosity of the obtained porous membrane is 50 % or more and 90 % or less, for example, and 60 % or more and 85 % or less are preferable.

<viscous liquid>

The viscous liquid is not particularly limited as long as it has a viscosity of 0.1 Pa·s or more, measured at 25°C using an E-type viscometer, and does not dissolve or deteriorate the filter upon contact for several minutes to 1 hour. .

In the above-mentioned viscous liquid, it is difficult to naturally release gas from the liquid due to its viscosity, and bubbles are stably present.

Moreover, in a filtration operation, when a viscous liquid moves in piping or a filter device, when the flow which entrains gas arises, bubbles may generate|occur|produce in a viscous liquid.

However, when the porous membrane formed by the above-described method is used to filter the viscous liquid, the number of bubbles in the viscous liquid can be effectively reduced.

In general, the higher the viscosity of the liquid, the more difficult it is to remove the bubbles. However, in the first purification method, the viscosity measured by an E-type viscometer at 25°C is 0.15 Pa·s or more, preferably 0.7 Pa·s or more, more preferably 1 Pa·s or more, still more preferably 1.5 It is particularly effective in reducing the number of bubbles in a viscous liquid of Pa·s or more.

Although it will not specifically limit if the upper limit of the viscosity of a viscous liquid can be filtered with a filter, 8.0 Pa.s or less are preferable, and 7.0 Pa.s or less are more preferable.

When the viscosity is excessively high, filtration by the original filter may be difficult.

The first refining method is preferably used, for example, for refining a liquid curable material used for forming an insulating film, an antireflection film, an adhesive layer, and a hard coat. When air bubbles are contained in such a liquid curable material, defects in appearance occur in the formed insulating film, antireflection film, adhesive layer, hard coat, and the like.

In particular, when an insulating layer, an antireflection film, an adhesive layer, a hard coat, etc. are transparent layers, in a display device or an optical device including these layers, the bubbles cause unwanted scattering or refraction of light, thereby deteriorating the performance of the device. have.

Moreover, as a purification object by the 1st purification method, a photoresist composition is also preferable. Air bubbles in the photoresist composition become defects in patterned films formed using the photoresist composition. Moreover, when a bubble exists in a photoresist composition, when a photoresist composition is apply|coated to a board|substrate, a bubble part will remain|survive in a coating film, and coating nonuniformity, such as a film thickness of that part becoming thin, tends to generate|occur|produce.

The composition of the photoresist composition is not particularly limited, and may be of a negative type or a positive type.

Moreover, as the object of purification by the first refining method, a raw material chemical solution such as a resin solution used for the above-mentioned curable material, photoresist composition, or the like is also preferable. In general, it is possible to effectively reduce the number of bubbles in the liquid by purifying the high-concentration and high-viscosity raw material chemical.

<Specific purification method of liquid>

In the first purification method, the above-mentioned viscous liquid is filtered using a filter including the porous membrane produced by the above-mentioned method. In a 1st manufacturing method, a viscous liquid is made to permeate|transmit from one side of a filter to the other side. Such permeation is typically performed by generating a differential pressure on one side and the other side of the filter.

As a method of using a porous membrane as a filter in a 1st purification method, the method of using a planar porous membrane, the method of using the porous membrane processed into the shape of a pipe, etc. are mentioned.

If the pipe-shaped porous membrane is also pleated, it is preferable because the contact area between the viscous liquid and the filter is increased. As will be described later, the porous membrane is appropriately sealed so that the supply liquid and the filtrate do not mix.

Purification of the viscous liquid can be carried out without differential pressure, ie, natural filtration by gravity, using the above-mentioned porous membrane, but it is preferably carried out by differential pressure.

It will not specifically limit, if it is a method of providing a pressure difference between one side and the other side of a porous membrane as a method of generating a differential pressure. As a method of generating the differential pressure, there are usually mentioned pressurization (positive pressure) in which pressure is applied to one side of the porous membrane (supply side), and reduced pressure (negative pressure) in which one side of the porous membrane (filtrate side) becomes negative pressure. and pressurization is preferred.

The pressurization is the application of pressure to the side (supply liquid side) of the polyimide-based resin porous membrane where the liquid before permeating the porous membrane (which may be referred to as "supply liquid" in this specification) exists. For example, it is preferable to apply the pressure by using the hydraulic pressure generated by circulating or feeding the supply liquid or by using the positive pressure of the gas.

The hydraulic pressure can be generated, for example, by an active hydraulic pressure adding method such as a pump (liquid feeding pump, circulation pump, etc.). Specific examples of the pump include a rotary pump, a diaphragm pump, a metering pump, a chemical pump, a plunger pump, a bellows pump, a gear pump, a vacuum pump, an air pump, and a liquid pump.

The hydraulic pressure may be, for example, a pressure applied to the porous membrane by the liquid when the liquid permeates through the porous membrane only by gravity. It is preferred that the pressure is applied by the positive hydraulic pressure application method described above.

The gas used for pressurization is preferably a gas that is inert or non-reactive with respect to the supply liquid, and specific examples thereof include nitrogen or rare gases such as helium and argon.

When the viscous liquid is a liquid used in the field of manufacture of electronic materials, particularly semiconductors and the like, pressurization is preferable. In that case, the side which collects the liquid which permeate|transmitted the porous membrane should just be atmospheric pressure which does not depressurize. As pressurization, the positive pressure by gas is preferable.

In addition, the said pressurization may pass through valves, such as a pressurization valve or a pressurization valve, or a three-way side.

The pressure reduction is a pressure reduction on the side (the filtrate side) that collects the liquid that has permeated the polyimide-based resin porous membrane. The reduced pressure may be, for example, reduced pressure by means of a pump. It is preferable to reduce the pressure to vacuum.

In the case of circulating or feeding the supply liquid by means of a pump, the pump is usually disposed between the supply liquid tank (or circulation tank) and the porous membrane.

The pressurization may use both the hydraulic pressure and the positive pressure of gas. Moreover, the differential pressure may combine pressurization and reduced pressure. For the pressurization, for example, both hydraulic pressure and reduced pressure may be used, both positive pressure and reduced pressure of gas may be used, and hydraulic pressure and positive pressure and reduced pressure of gas may be used.

When combining the method for forming a differential pressure, a combination of a hydraulic pressure and a positive pressure of a gas or a combination of a hydraulic pressure and a reduced pressure is preferable from the viewpoint of simplification of production and the like.

The pressure difference applied before and after the porous membrane by forming the differential pressure may be appropriately set according to the film thickness, porosity or average pore size of the porous membrane to be used, or desired degree of purification, flow rate, flow rate, concentration or viscosity of the feed solution, and the like.

In the case of what is called a cross-flow system (a supply liquid flows in parallel with respect to a porous membrane), 3 Mpa or less of the differential pressure|voltage is preferable, for example.

In the case of a so-called dead-end system (a supply liquid is flowed so that it may cross|intersect with respect to a porous membrane), 1 Mpa or less of differential pressure|voltage is preferable, for example.

When the differential pressure is excessively high, bubbles may be generated in the viscous liquid during filtration. When the differential pressure is within the above range, it is easy to filter the viscous liquid without generating bubbles.

In these systems, the lower limit of the differential pressure is not particularly limited, and is, for example, 10 Pa.

What is necessary is just to set the temperature during filtration suitably, for example, it is the range of 0 degreeC or more and 30 degrees C or less, Preferably it is 25 degreeC. With respect to the filtration temperature, a temperature gradient may be formed by the time difference of filtration, or a temperature difference may be provided on the side of the feed solution and the side of the filtrate.

In the first purification method, before supplying the viscous liquid to the porous membrane, it is preferable to prewet the porous membrane with a liquid different from the viscous liquid. By pre-wetting, the wettability of a viscous liquid and a porous membrane improves, while the improvement of the filtration rate of a viscous liquid can be anticipated, the bubble reduction effect becomes high.

As a liquid used for a pre-wet, alcohol, such as methanol, ethanol, and isopropyl alcohol, ketones, such as acetone and methyl ethyl ketone, water, etc. are mentioned. When the viscous liquid contains an organic solvent, other organic solvents may be used as the liquid used for pre-wet, for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol-n-propyl ether, ethylene Glycol mono-n-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, diethylene glycol mono-n-butyl ether, triethylene glycol monomethyl ether, triethylene glycol monomethyl ether Ethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-n-butyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, (poly)alkylene glycol monoalkyl ethers such as dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-n-butyl ether, tripropylene glycol monomethyl ether, and tripropylene glycol monoethyl ether; (poly)alkylenes such as ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, and propylene glycol monoethyl ether acetate glycol monoalkyl ether acetates; other ethers such as diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, and tetrahydrofuran; Ketones, such as methyl ethyl ketone, cyclohexanone, 2-heptanone, and 3-heptanone; lactic acid alkyl esters such as methyl 2-hydroxypropionate and ethyl 2-hydroxypropionate; 2-hydroxy-2-methyl ethyl propionate, 3-methoxy methyl propionate, 3-methoxy ethyl propionate, 3-ethoxy methyl propionate, 3-ethoxy ethyl propionate, ethoxy ethyl acetate, ethyl hydroxyacetate, 2 -Hydroxy-3-methylbutanoate, 3-methyl-3-methoxybutyl acetate, 3-methyl-3-methoxybutylpropionate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-acetic acid Butyl, isobutyl acetate, n-pentyl formate, isopentyl acetate, n-butyl propionate, ethyl butyrate, n-propyl butyrate, isopropyl butyrate, n-butyl butyrate, methyl pyruvate, ethyl pyruvate, n-propyl pyruvate, acetoacetic acid other esters such as methyl, ethyl acetoacetate, and ethyl 2-oxobutanoate; aromatic hydrocarbons such as toluene and xylene; and organic solvents such as amides such as N-methylpyrrolidone, N,N-dimethylformamide and N,N-dimethylacetamide. The liquid used for pre-wet can be used individually or in combination of 2 or more types.

It is preferable that the liquid used for pre-wet is a solvent containing 1 or more types of solvents contained in a viscous liquid, and it is more preferable that it is the same solvent as the solvent contained in a viscous liquid.

A method of contacting the liquid for pre-wet and the porous membrane before permeating the supply liquid is not particularly limited as long as it is a method capable of bringing the liquid for pre-wet into contact with the porous membrane.

As a preferable method, the method of making the liquid for pre-wet impregnate the inside of a porous film by making a porous film immersed in the liquid for pre-wet is mentioned.

The contact between the liquid for pre-wet and the porous membrane before permeating the viscous liquid may be performed by the above-described differential pressure. The range of the differential pressure is, for example, about 1 KPa or more and 0.25 MPa or less. In particular, in the case where the liquid for pre-wetting is also permeated into the pores inside the porous membrane, the pre-wetting may be performed under pressure. When pressurizing, it is preferable to carry out in the range of 0.01 Mpa or more and 0.25 Mpa or less.

By filtering the viscous liquid using the porous membrane as a filter according to the method described above, bubbles in the viscous liquid can be removed while preventing the generation of bubbles during filtration.

In the first purification method, the porous membrane can be used, for example, as a filter medium or other filter medium, and specifically, it may be used alone or may be used as a filter medium to provide another functional layer (membrane).

A porous membrane may be used as a membrane combined with another filter medium, and can also be used as a membrane used for a filter device etc., for example.

The functional layer that can be used in combination with the porous membrane is not particularly limited, and includes, for example, a nylon membrane, a polytetrafluoroethylene (PTFE) membrane, and a tetrafluoroethylene/perfluoroalkylvinyl ether copolymer (PFA). and a film having a chemical or physicochemical function, such as a film or a film obtained by modifying them.

«Second purification method»

The second purification method is a liquid purification method comprising filtering a viscous liquid having a viscosity of 0.1 Pa·s or more with a filter,

This is a method in which the filter contains a porous membrane having communicating pores including a structure in which spherical pores or substantially spherical pores communicate with each other.

The manufacturing method of the porous membrane used as a filter in a 2nd purification method is not specifically limited. Typically, the porous membrane containing the said predetermined structure is manufactured by the method demonstrated about the 1st manufacturing method.

In the second purification method, the viscous liquid is filtered using, as a filter, a porous membrane having communication pores including spherical pores or a structure in which substantially spherical pores are communicated with each other, thereby preventing the generation of bubbles during filtration and bubbles in the viscous liquid. can reduce the number of

The viscous liquid to be purified by the second purification method is the same as the method described for the first purification method.

In addition, the filtration method of the viscous liquid in the 2nd purification method is the same as the method demonstrated about the 1st purification method.

Example

Hereinafter, although an Example is shown and this invention is demonstrated more concretely, the scope of the present invention is not limited to the Example shown below.

In the Examples, the polyamic acid solution, organic solvent, dispersant, and microparticles shown below were used. Moreover, with respect to the particle size distribution index (d25/75) of each silica, silica (1) is about 1.5, and silica (2) is 1.6 or more.

ㆍPolyamic acid solution: reaction product of pyromellitic dianhydride and 4,4'-diaminodiphenyl ether (organic solvent: N,N-dimethylacetamide)

ㆍOrganic solvent (1): N,N-dimethylacetamide (DMAc)

ㆍOrganic solvent (2): gamma butyrolactone

ㆍDispersant: Polyoxyethylene secondary alkyl ether-based dispersant

ㆍfine particles: silica (1): silica with an average particle diameter of 2500 nm

Silica (2): silica having an average particle diameter of 3500 nm

- Etching liquid: isopropyl alcohol: water (mass ratio 6:4) 5 mass % solution of tetramethylammonium hydroxide (TMAH)

[Example 1]

To the polyamic acid solution, a dispersion of silica (1) (dispersion medium is DMAc) is added, and organic solvents (1) and (2) are further mixed with organic solvents (1) and (2) so that the solvent composition in the entire varnish is organic solvent (1): organic solvent ( 2) = 90:10, respectively, were added and stirred, and the varnish was prepared. In addition, the volume ratio of the polyamic acid and silica in the obtained varnish is 40:60 (mass ratio 30:70), and solid content concentration (concentration of a polyamic acid and a silica) is 33 mass %. The viscosity was 4.0 Pa·s.

After applying the above varnish to the substrate, prebaking at 70°C for 5 minutes, peeling the unbaked composite film from the substrate to obtain an unbaked composite film, and heat treatment (baking) at 400°C for 15 minutes each, and a polyimide-fine particle composite film was obtained. The obtained polyimide-fine particle composite film was immersed in a 20% HF solution to remove the fine particles contained in the film, then washed with water and dried to obtain a porous polyimide film.

Moreover, the opening diameter and communication hole of the surface of a polyimide porous membrane were expanded using etching liquid, and after water washing and drying, the heat process for 15 minutes was performed again at 350 degreeC. After reheating, the polyimide porous membrane 1 having a film thickness of about 40 µm, an air permeability of 20 seconds or less, a porosity of about 70% and an average pore diameter of 2500 nm was obtained. The average diameter of the communication holes confirmed by the porosimeter was 1000 nm.

[Example 2]

Except having used the silica (2) instead of the silica (1), it carried out similarly to Example 1, and obtained the polyimide porous membrane 2. The viscosity of the final varnish was 4.1 Pa·s. The polyimide porous membrane 2 had a film thickness of about 40 µm, an air permeability of 20 seconds or less, a porosity of about 70%, and an average pore diameter of 3500 nm. The polyimide porous membrane 2 had a communication hole exceeding 1000 nm.

[Comparative Example 1]

Except having adjusted so that the viscosity of the final varnish might be about 1.5 Pa.s, it carried out similarly to Example 1, and prepared the varnish. When an unbaked composite film was formed using the varnish of Comparative Example 1, the polyimide porous film could not be formed because sea islands were generated after prebaking.

[Example 3]

Using the filter device provided with the polyimide porous membrane 1 obtained in Example 1 as a filter, at room temperature, under the conditions shown in Table 1, resist composition for plating process (viscosity (25 degreeC, E-type viscometer): 3.9 Pa. s, the Tokyo Oka Kogyo Co., Ltd. make, propylene glycol monomethyl ether acetate (PGMEA) containing) was filtered.

As a test apparatus, the apparatus which consists of the structures of the following 1) - 6) was used.

1) Resist liquid tank.

2) A liquid supply pipe connecting the resist liquid tank and the liquid supply port of the filter device.

3) A liquid supply pump for supplying liquid to the filter while generating a differential pressure (filtration pressure) formed in the middle of the liquid supply piping.

4) A filter device with a filter.

5) A discharge liquid pipe connecting the discharge port of the filter device and the resist liquid tank.

6) Three-way side for sampling formed during discharge piping.

Filtration conditions are as having described in Table 1. In addition, before starting filtration, the filter was made to flow through about 4 L of PGMEA under the pressurization condition of 0.02 MPa, and the filter was pre-wetted.

First, at the start of filtration, 0.5 L of the resist composition was passed through the filter in the filter device, and the resist composition that had passed through the filter was discarded.

Next, 2 L of the resist composition was supplied from the resist liquid tank toward the filter. The filtrate generated by the 2 L supply was collected in a resist liquid tank.

100 ml of a sample of the filtrate at the time of supply of 2 L was recovered from 3 stools. This sample was designated as Sample 1.

Thereafter, 13 L of the resist composition was supplied to the filter device while a part of the resist composition was circulated through a circulating system comprising a resist liquid tank, a liquid supply pipe, a filter device, and a discharge liquid pipe. At the time of supply of 13 L (15 L in total), 100 ml of a sample of the filtrate was recovered from three stools. This sample was designated as Sample 2.

For Sample 1 and Sample 2, reduction in the number of foreign substances and reduction in the number of bubbles were evaluated according to the following method.

First, a sample of a resist composition is applied on a wafer, and then a film having a thickness of about 38 µm formed by pre-baking the coating film at 140° C. for 300 seconds is observed with an NSX-220 (manufactured by Rudolph), and per unit area The number of foreign substances and the number of bubbles were counted.

The same evaluation was performed also about the resist composition before filtration.

As a result of the above evaluation, reduction in the number of foreign substances was recognized in Samples 1 and 2.

Moreover, in Sample 1, the number of bubbles was reduced to 5% of the number of bubbles in the resist composition before filtration, and the number of bubbles in Sample 2 was equal to that of Sample 1.

[Comparative Example 2]

The resist composition was filtered in the same manner as in Example 3, except that the filter was changed to a filter made of PTFE fibers with an average pore diameter of 1 µm (1000 nm) and the filtration conditions were changed to those shown in Table 1. did.

As a result of confirming the number of bubbles in the resist composition obtained after filtration in the same manner as in Example 3, reduction in the number of foreign substances was confirmed for Samples 1 and 2.

However, in Sample 1, the reduction in the number of bubbles from the resist composition before filtration was not confirmed, and in Sample 2, the number of bubbles increased to about 100 times the number of bubbles before filtration.

Moreover, the test similar to the comparative example 2 was implemented by raising the differential pressure (filtration pressure) to 0.5 Mpa. In this test, the same increase in the number of bubbles as in Comparative Example 2 was confirmed even with a liquid passing amount smaller than Comparative Example 2.

[Example 4]

Using the filter device provided with the polyimide porous membrane 1 obtained in Example 1 as a filter, at room temperature, under the conditions shown in Table 2, resist composition for plating process (viscosity (25 degreeC, E-type viscometer): 1.0 Pa. s, Tokyo Oka Kogyo Co., Ltd. propylene glycol monomethyl ether acetate (PGMEA) and 3-methoxybutyl acetate (MA) containing) were filtered.

As a test apparatus, the apparatus which consists of the structures of the following 1) - 6) was used.

1) Resist liquid tank.

2) A liquid supply pipe connecting the resist liquid tank and the liquid supply port of the filter device.

3) A liquid supply pump for supplying liquid to the filter while generating a differential pressure (filtration pressure) formed in the middle of the liquid supply piping.

4) A filter device with a filter.

5) A discharge liquid pipe connecting the discharge port of the filter device and the resist liquid tank.

6) Three-way side for sampling formed during discharge piping.

Filtration conditions are as having described in Table 2.

First, at the start of filtration, 0.5 L of the resist composition was passed through the filter in the filter device, and the resist composition that had passed through the filter was discarded.

Next, 12 L of the resist composition was supplied to the filter device while a part of the resist composition was circulated through a circulating system comprising a resist liquid tank, a liquid supply pipe, a filter device, and a discharge liquid pipe. A sample of 100 ml of the filtrate at the time of supply of 12 L was recovered from 3 stools. This sample was designated as Sample 3.

About Sample 3, the reduction of the number of foreign substances and reduction of the number of bubbles were evaluated by the method similar to Example 3. Regarding the resist composition before filtration, the number of foreign substances and the number of bubbles were evaluated in the same manner as in Example 3.

As a result, in Sample 3, reduction in the number of foreign substances was recognized.

Moreover, the number of bubbles in Sample 3 was reduced to about 6% of the number of bubbles in the resist composition before filtration, and the number of foreign substances was reduced to about 2% of the number of bubbles in the resist composition before filtration.

[Comparative Example 3]

Except having changed the filter in a test apparatus to a PTFE nonwoven fabric, it carried out similarly to Example 4, and evaluated. Unlike Example 3, the number of bubbles in the sample was not reduced (about 80% of the number of bubbles in the resist composition before filtration remained), and the number of foreign substances was reduced only to about 41% of the number of foreign substances in the resist composition before filtration.

Claims (15)

A method for purifying a liquid, comprising filtering a viscous liquid having a viscosity of 0.1 Pa·s or more and 8.0 Pa·s or less with a filter, comprising:
the filter,
A composite film composed of the resin component (A) and the particles (B) by applying a varnish containing a resin component (A), particles (B), and a solvent (S) with a viscosity of 2.0 Pa·s or more on a substrate forming and
It contains a porous membrane obtained by a manufacturing method comprising removing the particle (B) in the composite membrane,
The resin component (A) contains at least one selected from the group consisting of polyamic acid and polyimide,
the particle (B) is a silica particle, the particle size of the particle (B) is more than 2000 nm and 3500 nm or less,
The solvent (S) is N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylformamide, N,N-diethylformamide , N-methylcaprolactam, N,N,N',N'-tetramethylurea, β-propiolactone, γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, and at least one solvent selected from the group consisting of ε-caprolactone. A method for purifying a liquid, comprising filtering a viscous liquid having a viscosity of 0.1 Pa·s or more and 8.0 Pa·s or less with a filter, comprising:
the filter,
It contains a spherical hole or a porous membrane having a communicating hole having a spherical degree of less than 1 ± 0.3 and a structure in which non-spherical spherical pores communicate with each other,
The purification method, wherein the spherical pores or sphericity is within 1 ± 0.3, and the average diameter of non-spherical spherical pores is more than 2000 nm and 3500 nm or less. A method for purifying a liquid, comprising filtering a viscous liquid having a viscosity of 0.1 Pa·s or more and 8.0 Pa·s or less with a filter, comprising:
the filter,
It contains a spherical hole or a porous membrane having a communicating hole having a spherical degree of less than 1 ± 0.3 and a structure in which non-spherical spherical pores communicate with each other,
The purification method, wherein the average pore diameter of the communication holes is 500 nm or more and 2000 nm or less. 3. The method according to claim 1 or 2,
The purification method, wherein the porous membrane has communication holes, and the average pore diameter of the communication holes is 500 nm or more and 2000 nm or less. The method of claim 1,
A purification method, wherein the particle (B) is removed with hydrogen fluoride water. 4. The method according to any one of claims 1 to 3,
wherein the viscous liquid comprises air bubbles. 4. The method according to any one of claims 1 to 3,
The purification method, wherein the Gurley air permeability of the porous membrane is 1 second or more and 20 seconds or less. 4. The method according to any one of claims 1 to 3,
and pre-wetting the filter with a liquid different from the viscous liquid before filtering the viscous liquid. Applying a varnish containing a resin component (A), particles (B), and a solvent (S) on a substrate to form a composite film comprising the resin component (A) and the particles (B);
A method for producing a porous membrane comprising removing the particles (B) in the composite membrane,
The resin component (A) contains at least one selected from the group consisting of polyamic acid and polyimide,
the particle (B) is a silica particle, the particle size of the particle (B) is more than 2000 nm and 3500 nm or less,
The solvent (S) is N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylformamide, N,N-diethylformamide , N-methylcaprolactam, N,N,N',N'-tetramethylurea, β-propiolactone, γ-butyrolactone, γ-valerolactone, δ-valerolactone, γ-caprolactone, and at least one solvent selected from the group consisting of ε-caprolactone,
The manufacturing method of which the viscosity of the said varnish is 2.0 Pa.s or more. 10. The method of claim 9,
The manufacturing method of which the particle diameter of the said particle|grain (B) is 2500 nm or more and 3500 nm or less. 10. The method of claim 9,
The porous membrane has spherical pores or spherical pores that are not spherical with a sphericity of 1 ± 0.3 or less,
The spherical hole or the spherical degree is within 1 ± 0.3, and the average diameter of the non-spherical spherical pores is more than 2000 nm and 3500 nm or less, the manufacturing method. 12. The method according to any one of claims 9 to 11,
The porous membrane has a spherical hole or a communication hole comprising a structure in which spherical holes, which are not spherical, communicate with each other with a sphericity of 1 ± 0.3 or less, and the average pore diameter of the communication holes is 500 nm or more and 2000 nm or less , manufacturing method. 12. The method according to any one of claims 9 to 11,
The production method according to claim 1, wherein the porous membrane is provided as a filter to a liquid purification method comprising filtering a viscous liquid having a viscosity of 0.1 Pa·s or more and 8.0 Pa·s or less. 12. The method according to any one of claims 9 to 11,
The Gurley air permeability of the said porous membrane is 1 second or more and 20 seconds or less, The manufacturing method. 12. The method according to any one of claims 9 to 11,
The manufacturing method whose solid content concentration of the said varnish is 25 mass % or more.