JPH10195212A - Production of fluororesin molding product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently produce the subject molding product having good antistatic effects and low contaminating properties while maintaining characteristics essential to a fluororesin by providing an antistatic layer comprising the fluororesin on the surface layer of a substrate comprising the fluororesin without substantially containing any ion exchange group. SOLUTION: A molding product comprising a fluororesin having groups convertible into ion exchange groups alone or a mixture thereof with a fluororesin without substantially containing any group convertible into the ion exchange groups is molded and the groups, present in the surface layer of the molding product and convertible into the ion exchange groups are converted into the ion exchange groups so as to provide preferably 0.25-20mol% concentration of the ion exchange groups in the surface layer to thereby afford the objective molding product. The thickness of the surface layer is preferably 1-500μm and <=80% based on the thickness of the molding product. A copolymer of tetrafluoroethylene and a monomer having the group convertible into the ion exchange group (e.g. CF2 =CFOCF2 SO2 F) can preferably be used as the fluororesin having the groups convertible into the ion exchange groups.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel method for producing a fluororesin molded article having antistatic properties. Specifically, by having an antistatic layer made of a fluororesin on the surface layer of a base made of a fluororesin that does not substantially contain an ion exchange group, while maintaining the characteristics inherent to the fluororesin,
This is a method for producing a fluororesin molded article having antistatic properties, which has a good antistatic effect and is capable of efficiently producing a fluororesin molded article having extremely low contamination.

[0002]

2. Description of the Related Art Fluororesins are excellent in chemical resistance, heat resistance, electrical insulation properties and stain resistance, and are used in a wide range of industrial fields. However, since the surface resistance of the fluororesin is extremely high, it has a large drawback that static electricity is easily charged.

For example, a fluororesin wafer carrier used in a semiconductor manufacturing process tends to adsorb fine particles in the atmosphere due to the charging property of the fluororesin. As a result, the fine particles adsorbed on the wafer carrier are retained on the wafer carrier. In addition, there is a problem in that the contaminated wafer is contaminated, and the defect rate of products obtained using the wafer is increased.

In a pipe for transferring a flammable liquid, static electricity is generated due to friction caused by the passage of the flammable liquid through the pipe, and there is a risk of ignition due to the static electricity.

[0005] Conventionally, there has been known a resin composition in which a conductive powder is blended with a fluororesin for the purpose of imparting an antistatic property to the fluororesin molded article, and a molded article comprising the composition. For example, JP-A-61-37842, JP-A-62-223255, JP-A-2-25575
No. 1 discloses a method for obtaining a molded product from a resin composition in which a carbon powder and a carbon fiber powder, or a conductive powder such as fibrous conductive titanium oxide and zinc oxide are mixed with a fluororesin such as tetrafluoroethylene. ing.

Japanese Patent Application Laid-Open No. 8-59864 discloses that
There is disclosed a method for producing a fluororesin molded body whose surface is made conductive by subjecting the surface layer of the fluororesin molded body to a plasma treatment to break C-F bonds into C = C bonds.

In order to impart hydrophilicity to a fluororesin molded article, Japanese Patent Application Laid-Open No. 1-98641 discloses that a hydrophilic monomer containing an ion-exchange group is irradiated by irradiation with a fluororesin porous tube. Discloses a method of graft polymerization on the surface of a polymer.

[0008]

However, among the above, the molded article obtained from the resin composition mixed with the conductive powder needs to be mixed with a large amount of the conductive powder in order to impart antistatic ability. Therefore, there is a problem that the conductive powder or impurities contained therein are eluted from the obtained fluororesin molded article. Such a problem causes a phenomenon that a substance coming into contact with the molded body is contaminated, and in particular, when the fluororesin molded body is used as a wafer carrier, the wafer carrier is caused by particles and the like due to the eluted conductive powder. This causes a phenomenon that the wafer held in the wafer is contaminated. Further, in the use of a pipe for transferring a fluid, there is a possibility that a phenomenon of contamination of the fluid may be caused.

[0009] Further, since the above-mentioned molded article is entirely made of a fluororesin containing the conductive powder, the electrical insulation properties and stain resistance, which are the properties of the fluororesin, are impaired, and such properties are required. Use is restricted in certain applications.

On the other hand, in the case of a method in which a hydrophilic monomer is introduced by a graft reaction for the purpose of imparting hydrophilicity, the fluororesin originally belongs to a decomposable resin in such a reaction, and the monomer and the like are quantitatively and quantitatively determined. It is difficult to introduce a large amount, and the ion-exchange groups are provided only at a very thin thickness of several hundred angstroms from the surface. Further, there is a concern that a resin decomposed by irradiating the surface of the fluororesin molded body with radiation may cause particles to be generated.

As a result, the fluororesin molded article obtained by the above-mentioned production method does not have a sufficient reduction in surface resistance, and there is still room for improvement in antistatic effect, contamination and the like.

[0012]

Means for Solving the Problems With respect to the above problems, the present inventors have made intensive studies. As a result, a molded article is formed from a fluororesin having a group that can be converted to an ion exchange group alone or a mixture of the fluororesin and a fluororesin having substantially no group that can be converted to an ion exchange group, By converting a group that can be converted to an ion exchange group present in the surface layer into an ion exchange group, it is possible to efficiently produce a fluororesin molded body that exhibits a good antistatic effect while maintaining the original electrical insulation characteristics of the fluororesin. They have found that they can be obtained well, and have completed the present invention.

That is, the present invention provides a method for molding a molded article comprising a fluororesin having a group which can be converted to an ion exchange group alone or a mixture with a fluororesin having substantially no group which can be converted to an ion exchange group. A method for producing a fluororesin molded article having an antistatic property, characterized in that a group convertible into an ion exchange group present on a surface layer of a molded article is converted into an ion exchange group.

In the present invention, as the fluororesin having a group that can be converted to an ion exchange group, a known fluororesin having the group and substantially having no ion exchange group is used without any particular limitation. For example, a copolymer of tetrafluoroethylene and a monomer having a group that can be converted to an ion exchange group is preferably used.

In this case, for the purpose of improving the moldability and physical properties of the copolymer, hexafluoropropylene of not more than 30 mol% based on tetrafluoroethylene, the following general formula: CF ₂ ＣＦCFO (CH ₂ ) _a C _b F _{2b +1} (where a is 0 or 1 and b is an integer of 1 to 10), or a mixture of fluorine-containing monomers such as alkyl vinyl ethers or monochlorotrifluoroethylene. .

The monomer having a group that can be converted to an ion-exchange group is a monomer having a group that can be converted to a perfluorosulfonic acid ion-exchange group. The following general formula: CF ₂ ＣＦCFO [CF ₂ CF (CF ₃ ) O] _o CF ₂ CFR _F
A monomer represented by SO ₂ X (where X is F or Cl, R _F is F or CF ₃ , and o is an integer of 1 to 3). Examples of the monomer having a group that can be converted include the following general formula: CF ₂ ＣＦCFO [CF ₂ CF (CF ₃ ) O] _p (CF ₂ ) _q Y (where Y is CO ₂ R (where R is a lower alkyl group) ), CN, COF, COCl, p is an integer of 1 to 3 and q is an integer of 2 to 8) or CF ₂ ＣＦCFO (CF ₂ ) _r OCF (CF ₃ ) Y ( However, a monomer represented by Y is CO ₂ R (where R is a lower alkyl group), CN, COF, and COCl, and r is an integer of 2 to 8 is preferably used.

Specific examples of these monomers having a group that can be converted into an ion exchange group include CF ₂ = CFOCF ₂ CF ₂ SO ₂ F and CF ₂ = CFOCF ₂ CF (CF ₃ ) OCF ₂ CF ₂ SO
₂ F, CF ₂ = CFOCF ₂ CF (CF ₃ ) OCF ₂ CF (C
_{F 3) OCF 2 CF 2 SO} 2 F, CF 2 = CFOCF 2 CF (CF 3) SO 2 F, CF 2 = CFOCF 2 CF (CF 3) OCF 2 CF (C
F ₃ ) SO ₂ F, CF ₂ ＣＦCFO (CF ₂ ) _3-8 CO ₂ CH ₃ , CF ₂ ＣＦCFOCF ₂ CF ₂ OCF ₂ CF (CF ₃ ) CO ₂ C
H _3, and the like.

Further, these monomers may be used alone or in combination.

For the copolymerization of the above tetrafluoroethylene with a monomer having a group which can be converted into an ion exchange group, a known method can be used without any limitation. That is, an optimal polymerization method may be selected in consideration of conditions such as copolymerizability among the solution polymerization method, suspension polymerization method, and emulsion polymerization method.

In any case, copolymerization is carried out by dissolving tetrafluoroethylene under pressure in a dispersion or solution of a monomer having a group that can be converted to an ion-exchange group. When another monomer is used in addition to the monomer or tetrafluoroethylene, if the monomer is a gas such as hexafluoropropylene, it is mixed with tetrafluoroethylene, and if the monomer is a liquid such as alkyl vinyl ether, a group that can be converted to an ion exchange group. May be mixed and polymerized.

In the case of emulsion polymerization or suspension polymerization using no organic solvent, water is suitable as a dispersion medium. On the other hand, in the case of solution polymerization or suspension polymerization using an organic solvent, the organic solvent acts as a chain transfer agent, lowering the molecular weight of the polymer, and the resulting copolymer may have poor physical properties. The solvent used is preferably a fluorine-based liquid.

Specific examples of such fluorine-based liquids include perfluorobutane, perfluoropentane, perfluorohexane, perfluoroheptane, perfluoroalkanes such as perfluorooctane, perfluorocyclobutane, perfluorocyclohexane and the like. Perfluorocycloalkanes, perfluoroethers, perfluorotertiary amines such as perfluorotributylamine, chlorofluoroethanes such as perfluoromorpholine and trifluoromonochloroethane are preferably used.

As the polymerization initiator, a persulfate such as ammonium persulfate is preferably used in the case of emulsion polymerization, and a known organic radical generator is used in the case of solution polymerization or suspension polymerization. In consideration of the heat resistance of the polymer, fluorine-based diacyl peroxides are preferably used, and specific examples thereof include the following.

(CF ₃ CF ₂ CO ₂ ) ₂ , (HCF ₂ CF ₂ CO ₂ ) ₂ , (ClCF ₂ CF ₂ CO ₂ ) ₂ , (CF ₃ CF ₂ CF ₂ CO ₂ )
₂ , (CF ₃ CF ₂ CF ₂ OCF (CF ₃ ) CO ₂ ) _{2 Further} , the pressure of the fluoroolefin at the time of polymerization cannot be unconditionally determined by the monomer composition and the polymerization temperature.
kg / cm ² -G is preferred. The polymerization temperature depends on the decomposition temperature of the polymerization initiator used, and thus cannot be determined unconditionally. However, it is usually 0 to 100 ° C., and 0 to 5 when a fluorine-based diacyl peroxide is used as the polymerization initiator.
0 ° C. is preferred.

The fluororesin having substantially no group capable of being converted into an ion exchange group is not particularly limited as long as it is a fluororesin having substantially no ion exchange group together with the group. , Copolymers of tetrafluoroethylene and alkyl vinyl ether, copolymers of tetrafluoroethylene and hexafluoropropylene, polymonochlorotrifluoroethylene, copolymers of tetrafluoroethylene and perfluorodimethyldioxole, polypar And fluoroalkenyl vinyl ether.

The alkyl vinyl ether is a perfluoroalkyl vinyl ether or a polyfluoroalkyl vinyl ether partially having a hydrogen atom. Specifically, a general formula: R _f (CH ₂ ) ₁ OCF ＝ CF ₂ (where R _f is a perfluoroalkyl group and 1 is 0 or 1) The alkyl vinyl ether is used in the resulting copolymer. Is 0.2% by weight or less, preferably,
It is preferable to use it in the range of 0.15% by weight or less.

In the present invention, the fluororesin having a group that can be converted to an ion exchange group is formed alone or mixed with a fluororesin having substantially no group that can be converted to an ion exchange group to form a molded article.

In this case, it can be converted to an ion exchange group in a fluororesin having a group convertible to an ion exchange group alone or a mixture of the fluororesin and a fluororesin having substantially no group convertible to an ion exchange group. The concentration of the group is such that the ion exchange group concentration when converted into an ion exchange membrane after molding is 0.25 to 20 mol%, preferably 0.25 to 1 mol%.
Concentration of a group that can be converted to an ion exchange group in a fluororesin having a group that can be converted to an ion exchange group, and / or a group that can be converted to an ion exchange group in the fluororesin having a group that can be converted to 8 mol%. It is preferable to appropriately adjust the mixing ratio with the fluororesin which does not substantially have the above in order to impart a sufficient antistatic effect to the obtained fluororesin molded article.

For mixing the fluororesin having a group which can be converted into the ion exchange group with the fluororesin having no ion exchange group, a known mixing method is employed without any limitation.
Examples include a Henschel mixer, a kneader brabender and the like.

A molded article made of a fluororesin having a group capable of being converted to an ion exchange group alone or a mixture of the fluororesin and a fluororesin having substantially no group capable of being converted to an ion exchange group (hereinafter referred to as "precursor") The molded article is also formed into an arbitrary shape according to the purpose. For example, a structure such as a wafer carrier, a tubular body such as a tube or a pipe, a thin formed body such as a sheet or a film, and the like can be given. Depending on the structure to be manufactured, injection molding, extrusion molding, transfer molding,
What is necessary is just to select suitably from well-known methods, such as compression molding and blow molding.

In the present invention, the conversion of a group which can be converted into an ion-exchange group present on the surface layer of the precursor molded body into an ion-exchange group can be carried out by any known method without any particular limitation. For example, when the group to be converted is a cation exchange group, a hydrolysis reaction under alkaline conditions is preferred. This hydrolysis reaction is carried out with several to several tens% of NaOH, KO.
The molded body may be immersed in an aqueous solution containing an alkali such as H or tetraalkylammonium hydroxide and heated at room temperature to 100 ° C. for several hours to one hundred and several tens hours. To promote this hydrolysis, it is effective to add an organic solvent such as methanol, ethanol, and dimethyl sulfoxide.

The ion exchange group provided by the above method is determined by the type of the group which can be converted into the ion exchange group present in the precursor molded article.

That is, depending on the type of the group that can be converted into an ion exchange group, for example, it is converted into a perfluoro cation exchange group or a polyfluoro anion exchange group. More specifically, the perfluorocation exchange group is a perfluorosulfonic acid group or a perfluorocarboxylic acid group (hereinafter, these perfluorosulfonic acid groups and perfluorocarboxylic acid groups are simply subjected to cation exchange. Group). The polyfluoro anion exchange group includes
And a polyfluoro quaternary ammonium group (hereinafter simply referred to as an anion exchange group). These ion exchange groups are chemically bonded to a fluororesin via a perfluorocarbon chain or a perfluoroether chain. I have.

[0034] To describe these ion exchange groups in more detail by the following general formula perfluorosulfonic acid group -CFR _F SO ₃ M (where, R _F is F or CF _3, M is a hydrogen atom, an alkali metal, Or a group represented by NR ′ ₄ (where R ′ is a hydrogen atom or a lower alkyl group).
The perfluoro carboxylic acid groups is represented by the following general formula -CFR _F CO ₂ M (where, R _F and M are as defined above.)
Anion exchange group ^{_{-CFR F CH 2 N + R "}} 3 Q - ( where, R _F is as defined above, R" is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, Q is a halogen atom .).

Of these ion exchange groups, cation exchange groups are generally more suitable than cation exchange groups because of their lower chemical resistance. Further, a perfluorosulfonic acid group is preferable because it has good heat resistance with respect to the perfluorocarboxylic acid group and has a higher antistatic ability than a perfluorocarboxylic acid group when the counter ion to be bonded is a hydrogen ion.

In the above conversion, the thickness of the antistatic layer formed on the surface layer of the precursor molded article is adjusted according to hydrolysis conditions. However, the conditions of the hydrolysis reaction cannot be determined unconditionally by the concentration and temperature of the alkali used, the type and amount of the organic solvent, the amount of the group that can be converted to an ion exchange group, the composition of the resin, and the like.

Accordingly, if the hydrolysis conditions and the concentration of the antistatic layer formed by hydrolysis in the thickness direction are measured in advance, the thickness of the antistatic layer can be adjusted within the range of the present invention. Depending on conditions, a concentration gradient is formed in which the surface has a high concentration of ion exchange groups and the concentration of ion exchange groups decreases in the thickness direction.
It is preferable to carry out the hydrolysis so that the thickness of the layer having a concentration of at least mol% is at least 1 μm. Under the antistatic layer, there is a layer having a concentration of ion exchange groups of less than 0.20 mol%, particularly 0.10 mol% or less. Of course, between the ion-exchanged layer and the non-formed part, the concentration of the ion-exchange groups may be any transition layer in between.

The hydrolysis is preferably carried out on the entire surface of the fluororesin molded body, but may be carried out on one side or a part thereof depending on the application.

The counter ion of the cation exchange group after hydrolysis is Na ion, K ion, hydrogen ion or ammonium ion, but other metal ions, hydrogen ions,
For conversion to ammonium ion, a known method is employed without any problem.

In the present invention, the antistatic layer formed on the surface layer of the precursor molded article generally has a surface resistivity of less than 10 ¹³ Ω, preferably 10 ¹⁰ Ω by the presence of an ion-exchange group at the above concentration. Hereinafter, a fluororesin molded article adjusted to the following is obtained.

In the present invention, the surface resistivity is determined by JI
It carried out according to the method of SK-6911.

The fluororesin molded article produced by the above-mentioned method of the present invention can be treated in the same manner as a conventional fluororesin, since there is a portion substantially free of ion exchange groups except for the surface layer. It is possible to substantially avoid the following problems which are observed in a fluororesin molded article in which an ion exchange group is present throughout the inside of the molded article.

That is, a molded article using a resin having an ion-exchange group as a whole, such as an ion-exchange membrane, undergoes dimensional changes due to swelling of the molded article when immersed in a solvent, a chemical solution, or the like. Alternatively, a phenomenon occurs in which organic substances are adsorbed and permeated.

For this reason, when used for the purpose of a wafer carrier, there is a possibility that a problem of contamination of a wafer coming into contact therewith may occur. For example, as a fluorine resin having an ion exchange group on a substrate, a fluorine-based ion exchange membrane or an ion exchange resin is known.
It is intended for adsorption, and usually contains about ten and several mol% of ion exchange groups. Therefore, in the field where the contamination resistance, which is a characteristic of the fluororesin, is required, such as the above-mentioned wafer carrier, the adsorption characteristics of the fluorine-based ion exchange membrane and the ion exchange resin for organic substances and ions are not preferable. In addition, there is also a problem that inorganic substances such as ions and water and organic substances such as alcohols are permeated and adsorbed even in the use of a molded article of a film or tube made of a fluororesin which requires antistatic ability.

In the present invention, taking the above points into consideration,
The thickness of the surface layer having an ion exchange group is 1 to 500 μm,
Further, it is preferable to carry out the conversion to the ion exchange group so that the thickness becomes 80% or less of the thickness of the molded body.

Specifically, when the fluororesin molded article is used for a wafer carrier or the like to be described later, the upper limit of the thickness of the layer containing the ion exchange group in the antistatic layer at a concentration of 0.25 mol% or more is used. Is preferably 80% or less, preferably 40% or less, more preferably 30% or less, with respect to the thickness of the molded body. In particular, the upper limit of the thickness of the layer is more preferably 500 μm or less in absolute thickness.

When the fluororesin molded article is used for applications such as thin films such as films and sheets, tubes and pipes described below, the properties of the fluororesin such as insulation, ion impermeability, and chemical resistance are given. In order to sufficiently exert the effect, it is preferable to control the upper limit of the thickness of the layer so that the thickness of the base material is 10 μm or more.

In the present invention, the antistatic layer is generally present on the entire surface of the molded product, but may be present on a part of the surface of the molded product depending on the application.

For example, a structure may be adopted in which an antistatic layer is provided on one side of a thin material such as a film or sheet, or on the inner or outer surface of a tube or pipe, and the other surface is not provided with an antistatic layer. . For example, it can be used satisfactorily for applications in which static electricity is a problem on one side of the fluororesin molding and static electricity is not a problem on the other side.

The thickness of the antistatic layer, the abundance of ion-exchange groups and the thickness of the substrate of the present invention are determined by infrared absorption spectrum (hereinafter referred to as I).
Abbreviated as R spectrum. ) Can be known by measuring. That is, a film is cut out from the surface of the fluororesin molded article of the present invention vertically at a thickness of several tens to several hundreds of μm, and the IR spectrum is transmitted from the surface at intervals of several μm,
Or by measuring the reflection spectrum, or by measuring from several to several tens of μm from the surface of the fluororesin molded body of the present invention and measuring the reflection spectrum of the cut surface,
If there is an ion exchange group characteristic absorption derived from the base, for example, 1060cm around ^-1, 1680 cm around ^-1,
And 1780cm respectively around ^-1 perfluorosulfonic acid salt (-SO ₃ Na), perfluoro carboxylate (-CO ₂ Na), and perfluoro carboxylic acid groups (-CO ₂ H) is observed, these absorption The portion with the mark can be determined as the thickness of the antistatic layer, and the amount of ion exchange groups can be determined from the absorption intensity.

On the other hand, when no ion-exchange group is present, these characteristic absorptions are not observed, and polytetrafluoroethylene, a copolymer of tetrafluoroethylene and alkyl vinyl ether, and a copolymer of tetrafluoroethylene and hexafluoropropylene are not observed. Coupling, absorption derived from polymonochlorotrifluoroethylene is 1200-1300cm
⁻¹ , as an absorption derived from a group that can be converted into an ion exchange group, around 1420 cm ^−1, around 1710 cm ⁻¹ , 1780
cm ^-1 vicinity, and 2100 cm ^-1 respectively perfluorosulfonic acid fluoride group near (-SO ₂ F), perfluoro carboxylic acid chloride group (-CO ₂ Cl), perfluoro carboxylic acid ester group (-CO ₂ CH ₃ ) And a perfluorocyano group (—CN) are observed, and the portion having the absorption can be determined as the thickness of each layer.

However, the present invention is not limited to the embodiment in which the ion-exchange groups in the fluororesin molded body other than the surface layer are completely absent. Is acceptable. Such an allowable amount cannot be unequivocally limited because the dimensional stability, adsorption, and permeability required for the application are different, but generally 0.2 mol in terms of a monomer containing an ion exchange group. %, Particularly preferably 0.1 mol% or less.

In the present specification, the amount of ion-exchange groups contained in the fluororesin is represented by the composition of the ion-exchange groups with respect to the monomer units of all monomers.

Such an antistatic layer is present on the surface of a substrate made of a fluororesin substantially containing no ion-exchange group, and by lowering the surface resistivity, a conventional conductive substance is added to improve the antistatic property. The application means is very useful in applications where the generation of particles from the surface is extremely small and contamination of articles coming into contact therewith, such as a wafer carrier, is a problem. Further, since a large amount of additives are not contained in the fluororesin serving as the base material, the fluororesin molded body has sufficient strength, and is most suitable for applications that require a physical load such as the wafer carrier. Also,
Compared to ion exchange resins that have ion exchange groups throughout,
Since the impurity ions do not penetrate into the interior, the adsorption amount of the impurity ions is small, and the contamination of the articles in contact with the obtained fluororesin molded article is extremely small.

[0055] The fluorine-containing resin molded article obtained by the method of the present invention, chemical adsorption amount measured by the method described later, 50 ppb / cm ² or less, particularly 10 ppb / cm ² or less.

From this, it is understood that the fluororesin molded article obtained by the method of the present invention is most suitable for the use in which contamination is a problem, such as the wafer carrier.

In the present invention, the antistatic effect of the obtained fluororesin molded article can be confirmed by the voltage decay rate. In general, a voltage of 10 kV is applied for 1 minute, and then the voltage decay rate after 1 second is 70%. Above, preferably 90%
The above is preferred.

[0058]

As will be understood from the above description, according to the method of the present invention, a layer having an ion-exchange group can be provided very reliably only on the surface of a fluororesin molded article. The antistatic property can be reliably provided while maintaining the original electrical insulation property of the molded article.

That is, while the ordinary fluororesin has a surface resistance of 10 ¹⁶ Ω or more and the voltage decay rate after one hour is several percent, according to the method of the present invention, the fluororesin molded article The surface resistance is less than 10 ¹³ Ω, and the voltage decay rate becomes almost 100% within a few seconds, so that it is possible to obtain a substantially non-charged fluororesin molded article.

Therefore, the fluororesin molded article having the antistatic layer produced according to the present invention hardly generates static electricity unlike the current fluororesin, and the dissipation when the static electricity is generated is fast. Further, since the fluororesin molded article produced by the present invention has substantially no ion-exchange group on the base material, when immersed in a chemical solution, there is no adsorption or permeation of ions or inorganic or organic substances, so that the chemical solution Fluorine resin is not contaminated, and when this fluororesin molded body is moved to other chemicals or water, it does not unnecessarily contaminate these chemicals or water, and there is no dimensional change of the molded body. Excellent properties inherent in the resin can be maintained.

As described above, the fluororesin molded article obtained by the method of the present invention is suitably used in the fields of semiconductor manufacturing industry, food industry, chemical industry, and general fields of physics and chemistry where generation of static electricity is reluctant. be able to.

More specifically, since there is no adhesion of dust and the like due to static electricity, chemical transfer tubes, joints, valves, check valves, strainers, chemical containers, vacuum tweezers, vacuum tweezer tips, Packing, O-ring, gasket, sheet, lining material, coating material, tweezers, tongs, dipper, holder, strainer, flasher, funnel, graduated cylinder, basket, stir bar, beaker, wipe cleaner, tank, bolt, nut, bottle, It can be suitably used for a mushroom, a tray, a plate heater, and the like.

As a jig such as a wafer carrier, a wafer carrier, a handle for a wafer carrier,
Box for wafer carrier, retainer, process tray, protector for wafer, wafer board, L
CD basket, LCD carrier, wafer tray,
Wafer tray cover, wafer tray spring, wafer pack, wafer shipper, mask carrier, mask carrier box, mask carrier handle, mask pack, mask case, device carrier, device carrier handle, side rail, chip tray, chip It can be suitably used for a tray cover, a chip tray case, a chip transfer tray, a chip cleaning carrier, a chip cleaning device, a chip tray box, and the like. In particular, since the wafer carrier made of the fluororesin molded article of the present invention is excellent in antistatic properties, not only can the adhesion of fine particles in a use atmosphere due to static electricity to the wafer be sufficiently effectively suppressed, but also the generation of particles and impurity ions No problems such as contamination by
As a result, there is an effect that the defect rate of the wafer can be kept low.

The tubes (including pipes) of the present invention
When a flammable liquid is transferred by using a liquid, the generation and accumulation of static electricity are prevented by the antistatic effect, so that not only the danger of ignition can be prevented, but also the generation of particles, swelling by the transferred liquid, and Is very useful without any problem of permeation of the transfer liquid.

Further, in the field of food production, the use of the molded article of the present invention can prevent the adhesion of dust, which is a hygiene problem. Therefore, the surface coating of equipment used in food production, for example, a mixer And a stirring blade, a tube, a tray, a belt, and the like.

[0066]

EXAMPLES The present invention will now be described in detail with reference to Examples, but it should be understood that the present invention is by no means restricted to such specific Examples.

The surface resistivity, the voltage decay rate, and the amount of adsorbed chemical solution of the fluororesin molding were determined as follows.

(1) Surface Resistivity The surface resistivity was measured according to JIS K-6911, and the surface resistivity was calculated by the following equation.

[0069]

(Equation 1)

Here, ρ _S : surface resistivity (Ω) d: outer diameter of inner circle of surface electrode (cm) D: inner diameter of annular electrode on surface (cm) R _S : surface resistance (Ω) Voltage 500 V measurement Time 30 seconds 3 times average (2) Voltage decay rate Using a static Honest meter S-5109 (manufactured by Shishido Shokai), a voltage of 10 kV was applied for 1 minute, and the voltage after the voltage was turned off was measured.

Resin size: 40 × 40 × 0.25 mm Attenuation rate = (initial voltage−voltage after time t) / initial voltage (unit:%) (3) Adsorption amount of chemical solution Ultrapure water was rinsed for 20 minutes. The test piece was placed in a washed 1-liter quartz container, 500 ml of sulfuric acid for electronics industry was added, and the mixture was kept at room temperature for 10 minutes to adsorb sulfuric acid to the test piece.

Next, the test piece was taken out, and 20
After rinsing for 500 minutes, 500 ml of ultrapure water was added and heated at 80 ° C. After elapse of 2 hours, ultrapure water was sampled and analyzed by ion chromatography, and the amount of sulfuric acid contained in the ultrapure water was calculated per 1 cm ^{2 of the} surface area of the test piece, which was defined as the adsorption amount of the drug solution.

REFERENCE EXAMPLE 1 After putting 320 g of 1,1,2-trichlorotrifluoroethane purified by distillation into a stainless steel 500 ml reactor having a stirrer, the inside was degassed, and then the mixture was largely flushed with nitrogen gas. Atmospheric pressure. 0.039 g of methanol in the reactor
After adding 33.5 g of CF ₂ = CFOCF ₂ CF (CF ₃ ) OCF ₂ CF ₂ SO ₂ F, the rotation speed of the stirring motor was set to 800, tetrafluoroethylene was introduced, and the pressure was increased to 4 kg / cm ^2. -G
I made it.

Then, while maintaining the inside of the reactor at 25 ° C., 1.77 of a 1,1,2-trichlorotrifluoroethane solution of bis (heptafluorobutyryl) peroxide (5% by weight) 1.77.
g was introduced to initiate polymerization. During the polymerization, the polymerization temperature is 25
C. 120 minutes after the start of the reaction, the pressure in the reactor was released, the reactor was connected to a vacuum pump via a cooling trap, and the pressure was reduced while stirring, and low boiling components such as a solvent and unreacted monomers were collected in the trap. . After the distillation, the reactor was disassembled, and the copolymer was taken out and vacuum-dried at 150 ° C. for 12 hours to obtain 24 g of the copolymer.

From the measurement results of the nuclear magnetic resonance spectrum and the infrared absorption spectrum, the copolymer was found to contain 95.7 mol% of a monomer unit based on tetrafluoroethylene and CF ₂ = CF
It was confirmed that monomer units based on OCF ₂ CF (CF ₃ ) OCF ₂ CF ₂ SO ₂ F were copolymerized by 4.3 mol%. The specific melt viscosity at 372 ° C. of the copolymer was 4.6 × 10
⁶ poise.

Example 1 The copolymer obtained in Reference Example 1 was melt-molded into a film having a thickness of 0.25 mm, and then NaOH / DMSO / H ₂ O = 15/25/60 wt.
%, And hydrolyzed at 100 ° C. for 24 hours to form an antistatic layer. When the abundance of ion exchange groups in this film was examined, it was about 4.3 mol% on the surface, about 0.28 mol% at 10 μm from the surface, 20 μm from the surface, and 0.08 mol% near the center. ,
0.02 mol%. Therefore, the thickness of the layer in which the concentration of ion exchange groups in the antistatic layer is 0.25 mol% or more is 10 μm.

Next, when the surface resistivity of this film was measured, it was 5.4 × 10 ⁸ Ω, and when the voltage decay rate was measured, it was 100% attenuated in one second. The film was measured for chemical adsorption to find that it was 1.0 ppb / cm ² . When this film was immersed in ion exchanged water overnight, no elongation due to swelling was observed.

Further, 0.2% obtained by the above method was obtained.
A particle generation test was performed on a 5 mm film. That is, first, the film is 5 cm × 10 c
m, and was rinsed with ultrapure water for 10 minutes in a class 1000 clean room. Thereafter, isopropyl alcohol for electronic industry was put into the container, shaken for 5 minutes, and then left. One day later, the isopropyl alcohol for electronics industry was replaced, and the mixture was shaken for 5 minutes and left. The same replacement operation was repeated, and after 1 day, 7 days, and 14 days, the number of particles of 0.3 to 2 μm contained in isopropyl alcohol was counted using a particle counter (manufactured by Lion Corporation, KL-2).
Measured using 2). 750 pieces / m after one day
1, particles were observed at 90 / ml after 7 days and at 45 / ml after 14 days.

The particles contained in isopropyl alcohol for electronics industry used in this experiment were 20 to 4 particles.
It was 0 / ml.

For comparison, the above film was heated to 350 ° C. with 5% by weight of conductive carbon and 5% by weight of carbon fiber powder with respect to 90% by weight of a copolymer of tetrafluoroethylene and alkyl vinyl ether. The mixture was mixed with a kneader brabender for 20 minutes, then melted at 350 ° C., and cooled under pressure to form a 0.25 mm thick sheet.

5 cm × 10 c cut from the above sheet
A particle generation test was performed on five m samples. 1250 cells / ml after 1 day, 1 after 7 days
140 particles / ml and 960 particles / ml were observed 14 days later.

Examples 2 to 4 Four kinds of copolymers were obtained in the same manner as in Example 1 except that the content of the groups that could be converted into ion-exchange groups was changed according to the method for producing the copolymer of Reference Example 1. Into a film having a thickness of 0.25 mm. Then, NaOH / DMSO / H ₂ O = 15/25 / 60wt%
, And hydrolyzed at 100 ° C. for 24 hours to form an antistatic layer.

In the film after hydrolysis, the ion exchange group concentration on the surface of the antistatic layer, the thickness of the layer having an ion exchange group concentration of 0.25 mol% or more, the surface resistivity, and the voltage decay rate after 1 second Table 1 shows the results of measurement of the chemical solution adsorption amount, and the elongation due to swelling in pure water.

[0084]

[Table 1]

Examples 5 to 7 Copolymers were prepared in the same manner as in Reference Example 1 except that monomers shown in Table 2 were used as monomers having a group which can be converted into an ion exchange group in the method for producing a copolymer of Reference Example 1. A coalescence was obtained.

Next, in the same manner as in the first embodiment, the thickness is 0.25 mm.
Melt molded into a film of NaOH / DMSO / H ₂ O = 15/25 / 60wt%
And hydrolyzed at 100 ° C. for 24 hours.

The content of the ion-exchange groups on the surface of the antistatic layer, the thickness of the layer having a concentration of the ion-exchange groups of 0.25 mol% or more, the surface resistivity, the voltage decay rate after one second, the adsorption amount of the chemical solution, Table 2 shows the results of measuring the elongation due to swelling in pure water.

[0088]

[Table 2]

Example 8 The copolymer obtained in Reference Example 1 was melt-molded into a film having a thickness of 0.25 mm, immersed in a solution of NaOH / DMSO / H ₂ O = 15/25/60 wt%, and Hydrolysis was performed at 120 ° C. for 120 hours. The thickness of the layer having an ion exchange group concentration of 0.25 mol% or more in the antistatic layer of the obtained film was 40 μm.

When the surface resistivity of the film was measured, it was 1.6 × 10 ⁸ Ω, and when the voltage decay rate was measured, the film attenuated 100% in one second. Further, the film was measured for chemical solution adsorption to find that it was 1.1 ppb / cm ² .
When this film was immersed in ion exchange water overnight, the elongation due to swelling was 0.1%.

Example 9 The copolymer obtained in Reference Example 1 was melt-molded into a film having a thickness of 0.25 mm, immersed in a solution of KOH / DMSO / H ₂ O = 15/25/60 wt%, and Hydrolysis was carried out at 24 ° C. for 24 hours.
The thickness of the layer having an ion exchange group concentration of 0.25 mol% or more in the antistatic layer of the obtained film was 10 μm. The measured surface resistivity was 4.4 × 10 ⁸ Ω. Further, when the voltage decay rate was measured,
Attenuated 0%.

Example 10 The copolymer obtained in Reference Example 1 was melt-molded into a film having a thickness of 0.25 mm, and then NaOH / DMSO / H ₂ O = 15/25/60 wt.
% Solution and hydrolyzed at 100 ° C. for 24 hours. This is immersed in a 1N hydrochloric acid solution, and
Stirred for hours. The thickness of the layer having an ion exchange group concentration of 0.25 mol% or more in the antistatic layer of the obtained film was 10 μm. The measured surface resistivity of the film was 1.1 × 10 ⁹ Ω. Further, when the voltage decay rate after 1 second was measured, it was 100% attenuated in 1 second.

Example 11 The film obtained in Example 10 was immersed in aqueous ammonia and stirred for 24 hours. When the surface resistivity of the obtained film was measured, it was 3.1 × 10 ⁹ Ω. Further, when the voltage decay rate after 1 second was measured, it was 100% attenuated in 1 second.

Examples 12 to 14 Polytetrafluoroethylene (hereinafter referred to as PTFE), a copolymer of tetrafluoroethylene and alkyl vinyl ether (hereinafter referred to as PFA), or a copolymer of tetrafluoroethylene and hexafluoropropylene The copolymer (hereinafter referred to as FEP) and the copolymer obtained in Example 4 were mixed in a powder state, and the thickness was 0.25.
melt-formed into a film with a thickness of NaOH / DMSO / H ₂ O = 15/25/60
It was immersed in a wt% solution and hydrolyzed at 100 ° C. for 24 hours.

The mixing ratio of the base material and the fluororesin having a group that can be converted to an ion exchange group, the content of the ion exchange group on the surface in the antistatic layer of the obtained film, and the concentration of the ion exchange group of 0.25 mol% The thickness of the above layers, surface resistivity,
The voltage decay rate after 1 second, the amount of adsorbed chemical solution, and the elongation due to swelling in pure water were measured. The results are shown in Table 3.

[0096]

[Table 3]

Example 15 The copolymer obtained in Reference Example 1 was melt-molded into a film having a thickness of 1 mm, immersed in a solution of NaOH / DMSO / H ₂ O = 15/25/60 wt%, and heated at 100 ° C. Hydrolysis was performed for 150 hours.

The concentration of ion-exchange groups in the obtained film was about 100 μm, 280 μm and 33 μm from the surface.
The concentration at 0 μm averaged 4.3 mol%, 3.7 mol%,
It was 3.5 mol% and 0.1 mol%, and no ion exchange group was detected near the center. From this, it can be said that the thickness of the antistatic layer is about 300 μm. The measured surface resistivity was 1.4 × 10 ⁸ Ω. Further, when the voltage decay rate was measured, the voltage decayed 100% in 1 second.

Example 16 The film obtained in Example 6 was immersed in 1N hydrochloric acid.
The mixture was stirred at 30 ° C. for 24 hours to convert the ion-exchange groups into acid form.
The surface resistivity of this film was measured to be 2.1 × 1
0 ¹² Ω. The voltage decay rate after one second was 76%.

Reference Example 2 According to the production method of Reference Example 1, CF ₂ = CFOCF ₂ CF (CF ₃ ) OCF ₂ CF ₂
4.8 mol% of SO ₂ F and tetrafluoroethylene
A copolymer with 2 mol% was prepared.

Example 17 From the copolymer obtained in Reference Example 2, a 6-inch wafer carrier (capacity: 25 sheets: schematically shown in FIG. 1) was formed by an injection molding method. This wafer carrier is immersed in a solution of NaOH / DMSO / H ₂ O = 15/25/60 wt%,
Hydrolysis was performed at 0 ° C. for 24 hours.

A part of the obtained wafer carrier was cut out, and the concentration of ion-exchange groups in the antistatic layer was 0.2%.
As a result of measuring the thickness of the layer of 5 mol% or more, it was 15 μm.

After setting the wafer in this wafer carrier, it was left in a class 1000 clean room for 24 hours. During this time, five particles of 0.3 μm or more adhered to the entire surface of the wafer held at the end of the wafer carrier.

Next, when the surface resistivity of this wafer carrier was measured, it was 1.8 × 10 ⁸ Ω. A part of the wafer carrier was cut out, and the voltage decay rate was measured to be 100% in one second.

Comparative Example 1 A wafer carrier was formed in the same manner as in Example 16 except that a commercially available PFA was used. After setting the wafer, the wafer was allowed to stand in a Class 1000 clean room for 24 hours. About 300 particles of 0.3 μm or more adhered to the held wafer.

Next, when the surface resistivity of the wafer carrier was measured, it was> 1 × 10 ¹⁴ Ω. A part of the wafer carrier was cut out, and the voltage decay rate was measured. The voltage decay rate was 0.8% after 5 minutes and 6% after 30 minutes.

Example 18 PFA and the copolymer obtained in Example 4 3: 2 (weight ratio)
From the above mixture, a 6-inch wafer carrier (25 sheets capacity: schematically shown in FIG. 1) was formed by an injection molding method. This wafer carrier was loaded with NaOH / DMSO / H ₂ O = 15
/ 25 / 60wt% solution and hydrolyzed at 100 ° C for 24 hours.

A part of the obtained wafer carrier was cut out, and the concentration of ion-exchange groups in the antistatic layer was 0.2%.
As a result of measuring the thickness of the layer of 5 mol% or more, it was 14 μm.

After setting the wafer in this wafer carrier, it was left in a class 1000 clean room for 24 hours. During this time, five particles of 0.3 μm or more adhered to the entire surface of the wafer held at the end of the wafer carrier.

Next, when the surface resistivity of this wafer carrier was measured, it was 1.9 × 10 ⁸ Ω. A part of the wafer carrier was cut out, and the voltage decay rate was measured to be 100% in one second.

Example 19 Using the copolymer obtained in Reference Example 2, a tube having an outer diameter of 8 mm and an inner diameter of 6 mm was formed by extrusion molding. This tube was immersed in a solution of NaOH / DMSO / H ₂ O = 15/25/60 wt%, and hydrolyzed at 100 ° C. for 24 hours. The measured surface resistivity was 4.1 × 10 ⁸ Ω, and the voltage decay rate was 100% in one second. The concentration of ion-exchange groups in this tube was near the surface, and the concentration at about 50 μm and 70 μm from the surface was 4.7 mol%, 3.8 mol% and 0.1 mol% on average. Can be said to be about 65 μm.

Example 20 PFA and the copolymer obtained in Example 4 3: 2 (weight ratio)
From the mixture by extrusion molding method,
mm tube was molded. Transfer this tube to NaOH / DMS
It was immersed in a solution of O / H ₂ O = 15/25/60 wt% and hydrolyzed at 100 ° C. for 24 hours. The measured surface resistivity was 4.5 × 10 ⁸ Ω, and the voltage decay rate was 100% in one second.
Met. The concentration of the ion-exchange groups in this tube was near the surface, and the concentrations at about 50 μm and 70 μm from the surface were 4.5 mol%, 3.7 mol% and 0.1 mol% on average. Can be said to be about 65 μm.

Comparative Example 2 Using the copolymer obtained in Reference Example 2, a tube having an outer diameter of 8 mm and an inner diameter of 6 mm was formed by extrusion molding. This tube was immersed in a solution of NaOH / DMSO / H ₂ O = 15/25/60 wt% and hydrolyzed at 100 ° C. for 7 days. The tube was cut open and the surface resistivity was measured to be 4.0.
× 10 ⁸ Ω, and the voltage decay rate was 100% in one second. The content of the ion-exchange groups in the central part was 3.2 mol%, and conversion to the ion-exchange groups was carried out over all layers. When this tube was immersed in pure water overnight, the elongation due to swelling in the length direction and the diameter direction was 4.8% and 5.3%, respectively, and the permeation amount of the drug solution was 7 × 10 5.
^-9 g · cm / cm ² · s.

Example 21 In Reference Example 1, CF ₂ = CFOCF ₂ CF ₂ CF ₂
A copolymer was obtained in the same manner except that CO ₂ CH ₃ and tetrafluoroethylene were used. This copolymer is CF ₂ = CFOCF ₂ CF
_It contained 4.2 mol% of monomer units derived from ₂ CF ₂ CO ₂ CH ₃ . This copolymer is melt molded to a thickness of 0.35 m.
m. The film was heated in phosphorous pentachloride / phosphorous oxychloride at 120 ° C. for 24 hours. Next, the membrane was washed and dried, and then reacted with dimethylamine in dry ether. Next, this membrane was reacted with sodium borohydride in dry diclimb for 100 hours at 100 ° C. for 18 hours to reduce, and then reacted with methyl iodide in methanol solution at 60 ° C. for 16 hours to convert to an anion exchange group. . As a result of IR analysis, the concentrations of the ion-exchange groups at and near the surface and at 75 μm and 120 μm from the surface were 3.8 mol%, 0.26 mol% and 0 mol%, and the antistatic layer was 75 μm. When the surface resistivity of the obtained film was measured, it was 4.5 × 10 ⁸ Ω, and the voltage decay rate after one second was 100%.

Example 22 The copolymer obtained in Reference Example 1 was melt-molded into a film having a thickness of 0.25 mm, immersed in a solution of NaOH / DMSO / H ₂ O = 15/25/60 wt%, and Hydrolysis was performed at 72 ° C for 72 hours.
As a result of IR spectrum measurement, the ion exchange group abundance at the film surface and at 50 μm, 60 μm, and 70 μm from the surface was 3.8 mol%, 3.7 mol%, 0.25 mol%,
The content was 0.01 mol%, and no ion exchange group was detected near the center. Therefore, it can be said that the thickness of the antistatic layer of this film is 60 μm. When the surface resistivity of this film was measured, it was 5.2 × 10 ⁸ Ω, and when the voltage decay rate was measured, the film attenuated 100% in about 1 second. The adsorption of the drug solution was 0.9 ppb / cm ² , and when the sample was immersed in ion-exchanged water overnight, the elongation due to swelling was 0.1%.

Comparative Example 3 The copolymer obtained in Reference Example 1 was melt-molded into a film having a thickness of 0.25 mm, immersed in a solution of NaOH / DMSO / H 2 O = 15/25/60 wt%, and heated at 100 ° C. Hydrolysis was performed for 168 hours. As a result of IR spectrum measurement, the ion exchange group abundance at the film surface, 50 μm from the surface and near the center was 4.3.
Mol%, 1.0 mol%, and 0.8 mol%, and were converted to ion-exchange groups in all layers. When the surface resistivity was measured, it was 3.8 × 10 ⁸ Ω, and when the voltage decay rate was measured, it was 100% attenuated in one second. The chemical adsorption is 6
It was 5 ppb / cm ² , and when it was immersed in ion-exchanged water overnight, it expanded about 4.5% due to swelling.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a typical structure of a wafer carrier constituted by a fluororesin molding of the present invention.

[Explanation of symbols]

 1 Wafer carrier body 2 Wafer holding groove

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI // C08L 27/12 C08L 27/12

Claims (3)

[Claims] A molded article comprising a fluororesin alone having a group capable of being converted to an ion exchange group or a mixture of the fluororesin and a fluororesin having substantially no group capable of being converted to an ion exchange group, A method for producing a fluororesin molded article having an antistatic ability, comprising converting a group that can be converted into an ion exchange group present on the surface layer of a molded article into an ion exchange group. 2. The method according to claim 1, wherein the concentration of the ion-exchange groups in the surface layer is 0.5.
The method for producing a fluororesin molded product according to claim 1, wherein the fluororesin molded product is prepared to be 25 to 20 mol%. 3. The surface layer has a thickness of 1 to 500 μm, and
The method for producing a fluororesin molded article according to claim 1 or 2, wherein the thickness is 80% or less of the thickness of the molded article.