Resin pellets and their molded products

Abstract

To provide a resin pellet that is suitable for molding a molded product used in a semiconductor manufacturing apparatus and inherently has high cleanliness, and a molded product including the resin pellets used in a semiconductor manufacturing apparatus.SOLUTION: A resin pellet includes at least one kind selected from tetrafluoroethylene homopolymers or copolymers, wherein an evaporation residue after evaporating and drying an extract obtained by dissolving and extracting a fluorine-containing substance contained in or adhering to the resin pellet in a fluorine-containing extractant is 20×10-6 mg / mm2 or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to resin pellets that can be suitably used for molding articles used in semiconductor manufacturing equipment, and to molded articles such as liquid transport molded articles and / or liquid contact molded articles used in semiconductor manufacturing equipment, which are molded using the resin pellets. [Background technology]

[0002] As the circuit patterns of semiconductor devices become finer, denser, and more integrated, and the wiring becomes multi-layered, the manufacturing process becomes more complicated and the number of steps continues to increase. As a result, the size of defects in the circuit patterns of semiconductor devices becomes smaller and smaller. For this reason, the materials and processes used in semiconductor manufacturing equipment themselves can be a source of contamination, and minute (extremely small) contaminants such as particles (foreign particles), metal impurities, and chemical contaminants at semiconductor manufacturing sites are increasingly affecting the yield and reliability of semiconductor products (Non-Patent Document 1). In the case of particles, even fine particles of submicron size can cause defects that lead to failure when they adhere to the wafer surface, so even the removal of submicron particles is required. Therefore, in order to suppress the occurrence of defects in the circuit patterns of fine semiconductor devices and to reduce particles larger than the circuit pattern size, it is becoming increasingly important to have clean materials and processes used in semiconductor manufacturing equipment that prevent particles from adhering to the wafer (low particle and low metal).

[0003] In semiconductor manufacturing equipment, fluororesin molded products are increasingly being used, taking advantage of the properties of fluororesin. However, particles (fine foreign matter particles) tend to adhere to the surface of fluororesin molded products, and it is not easy to remove even minute submicron-sized particles that can adhere to the wafer surface and cause defects that lead to failure. Normally, cleaning of fluororesin molded products used in semiconductor manufacturing is carried out using dilute aqueous solutions of surfactants, strong acids, ultrapure water, etc., but these methods require a long time for cleaning, and it is difficult to achieve a level of cleanliness that meets the requirements for fluororesin molded products used in semiconductor manufacturing equipment.

[0004] For this reason, a treatment method for removing fine particles adhering to fluororesin molded articles used in semiconductor manufacturing has been proposed (Patent Document 1).However, the treatment method proposed in Patent Document 1 requires special equipment and cannot be carried out by simple means, and it is difficult to achieve a level of cleanliness that satisfies the requirements for fluororesin molded articles used in semiconductor manufacturing.

[0005] Furthermore, the chemicals used to clean fluororesin molded products used in semiconductor manufacturing equipment are expensive and have a high environmental impact. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 08-005140 [Patent Document 2] Special Publication No. 2012-518010 [Non-patent literature]

[0007] [Non-Patent Document 1] "New Edition: Silicon Wafer Surface Cleaning Technology", Realize Co., Ltd., 2000, by Takeshi Hattori Summary of the Invention [Problem to be solved by the invention]

[0008] The present inventors have conducted intensive research in order to solve the above-mentioned problems of the conventional technology, and as a result, have discovered resin pellets used for molding molded products for use in semiconductor manufacturing equipment, which resin pellets themselves have high cleanability, thereby arriving at the present invention. The present invention also provides a molded article made of said resin pellets for use in semiconductor manufacturing equipment, which molded article itself has high cleanability. [Means for solving the problem]

[0009] The present invention relates to a resin pellet having high cleanability, which is used for molding a molded product for use in a semiconductor manufacturing device, and which is made of tetrafluoroethylene. N A resin pellet containing at least one kind selected from the group consisting of a fluorine-containing polymer, and a fluorine-containing substance contained in or attached to the pellet that has been washed with a fluorine-containing cleaning agent is dissolved and extracted in a fluorine-containing extractant, and the extract is filtered using a polypropylene filter membrane having a membrane diameter of 0.2 μm. The resulting extract is evaporated to dryness, and the evaporation residue is 0 to 1.0 × 10 -6 mg / mm 2 Within the range The tetrafluoroethylene (TFE) copolymer is a copolymer of tetrafluoroethylene (TFE) and 1 to 60 mol % of a comonomer, and is, for example, a TFE / hexafluoropropylene (HFP) copolymer (FEP), a TFE / perfluoro(alkyl vinyl ether) (PAVE) copolymer (PFA), an ethylene / TFE copolymer (ETFE), a TFE / HFP / PAVE copolymer, a TFE / HFP / vinylidene fluoride copolymer (THV), a TFE / ethylene / perfluorodimethyldioxole copolymer, or a TFE / CF 2 =CFOCF 2 CF(CF 3 )OCF 2 CF 2 SO 2 and at least one selected from the group consisting of perfluoroolefins and alkoxyperfluoroalkenes, and the fluorine-containing extractant is decafluoropentane. Resin pellets are provided.

[0010] In the resin pellets of the present invention, 、 (1) The tetrafluoroethylene (TFE) copolymer is A copolymer of tetrafluoroethylene (TFE) and 1 to 30 mol % of perfluoro(alkyl vinyl ether) (PAVE), selected from TFE / perfluoro(methyl vinyl ether) (PMVE) copolymer, TFE / perfluoro(ethyl vinyl ether) (PEVE) copolymer, TFE / perfluoro(propyl vinyl ether) (PPVE) copolymer, and TFE / perfluoro(butenyl vinyl ether) copolymer. At least one species, (2) The above The fluorine-containing cleaning agent is a perfluoroolefin or alkoxyperfluoroalkene having a boiling point in the range of 0 to 120°C and a boiling point difference of 10°C or more with respect to the fluorine-containing substance. That is, is a preferred embodiment.

[0011] The present invention also provides Copolymers of tetrafluoroethylene (TFE) and 1 to 60 mol% of a comonomer, such as TFE / hexafluoropropylene (HFP) copolymer (FEP), TFE / perfluoro(alkyl vinyl ether) (PAVE) copolymer (PFA), ethylene / TFE copolymer (ETFE), TFE / HFP / PAVE copolymer, TFE / HFP / vinylidene fluoride copolymer (THV), TFE / ethylene / perfluorodimethyldioxole copolymer, TFE / CF 2 =CFOCF 2 CF(CF 3 )OCF 2 CF 2 SO 2 tetrafluoroethylene copolymer, which is at least one selected from the group consisting of F copolymers and mixtures of these copolymers; A resin pellet containing At least one selected from perfluoroolefins and alkoxyperfluoroalkenes The present invention provides a method for producing the above resin pellets, which comprises washing the pellets with a fluorine-containing detergent. In the method for producing resin pellets of the present invention, ,before In a preferred embodiment, after the cleaning with the fluorine-containing cleaning agent, further cleaning with an acid or alkaline solution is carried out.

[0012] The present invention further provides a molded article made from the above resin pellets. In the above molded article of the present invention, (1) The fluorine-containing substances contained in or attached to the above-mentioned molded article are dissolved and extracted in a fluorine-containing extractant, and the extract is evaporated to dryness, and the evaporation residue is 0~1.0×10 -6 mg / mm 2 Range That is, (2) It is a molded product having a hollow part. (3) The product is cleaned with a fluorine-containing cleaning agent, particularly at least one fluorine-containing cleaning agent selected from hydrofluorocarbons, perfluorocarbons, and fluorine-containing ethers. (4) After cleaning with the fluorine-containing cleaning agent, the material is further cleaned with an acid or alkaline solution. is a preferred embodiment. Effect of the Invention

[0013] The present invention provides resin pellets that have high cleanability and can be suitably molded into molded articles for use in semiconductor manufacturing equipment. The melt flow rate (MFR) of the resin pellets is equivalent to that of the resin pellets before cleaning, so that the molding conditions for the molded articles can be used without changing them. According to the present invention, there is provided a fluororesin molded article made of said resin pellets and used in semiconductor manufacturing equipment, which article itself has high cleanability. The present invention provides molded articles, such as molded articles for transferring liquids and molded articles for contacting liquids, which are used in semiconductor manufacturing equipment and have high cleanability themselves, and therefore makes it possible to manufacture circuit patterns for semiconductor devices with semiconductor manufacturing equipment using these molded articles while suppressing the occurrence of defects. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] (Resin pellets) The resin pellets of the present invention are resin pellets containing at least one selected from homopolymers or copolymers of tetrafluoroethylene (TFE), and the fluorine-containing substances contained in or attached to the resin pellets are dissolved and extracted in a fluorine-containing extract, and the extract is evaporated to dryness, so that the evaporation residue is 20×10 -6 mg / mm 2 The important feature of the present invention is that it has high cleanability, which makes it suitable for molding products used in semiconductor manufacturing equipment.

[0015] (Fluorine-containing materials) The fluorine-containing substances contained in or attached to the resin pellets of the present invention contain carbon and fluorine, and are formed by thermally decomposing unstable terminal groups in a tetrafluoroethylene homopolymer and a TFE copolymer, and solidifying the fluorine-containing gaseous decomposition products as the temperature is lowered. These fluorine-containing substances are contained in or attached to the resin pellets in extremely small amounts. Such fluorine-containing substances are compounds that are difficult to quantitatively analyze because they have an extremely small amount of adhesion (content) per unit area, and also have the property of being highly resistant to hydrocarbon organic solvents and being difficult to dissolve in hydrocarbon organic solvents, and therefore cannot be detected even by gas chromatography / mass spectrometry (GC / MS).In addition, they are compounds with non-polar to medium polarity, low molecular weight, start to decompose at about 150°C, and vaporize at about 300°C or less. Such fluorine-containing substances are undesirable because they adhere to the wafer surface during the semiconductor manufacturing process and become nano-sized particles (foreign fine particles) that can cause defects in the circuit patterns of fine semiconductor devices. However, in the resin pellets of the present invention, the evaporation residue described above is as close to zero as possible, and is less than 20×10 -6 mg / mm 2 As can be seen from the reduction below, such fluorine content has been significantly reduced.

[0016] (evaporation residue) In the resin pellets of the present invention, the fluorine-containing substances contained in or attached to the resin pellets are extracted into a fluorine-containing extractant, and the extract is evaporated to dryness, leaving an evaporation residue as close to zero as possible, and less than 20×10 -6 mg / mm 2 Preferably, 0 to 10×10 -6 mg / mm 2 More preferably, the range is 0 to 1.0 × 10 -6 mg / mm 2 Resin pellets with evaporation residues in this range have reduced causative substances (fluorine-containing substances) that adhere to the wafer surface during the semiconductor manufacturing process and cause defects in the circuit patterns of fine semiconductor devices, leading to the generation of nano-sized particles with particle sizes of 300 nm or less, especially 50 nm or less. Therefore, a molded article using the resin pellets of the present invention as a molding material is a fluororesin molded article in which the generation of nano-sized particles (foreign fine particles) is suppressed. In addition, substances that cause the generation of nano-sized particles of 50 nm or less include metal ions or metal fine particles in addition to the above-mentioned fluorine-containing substances. Metal ions easily bond with fluorine ions, so that the metal ions or metal fine particles may become nuclei to form aggregates of the fluorine-containing substances. In the present invention, it is possible to reduce aggregates of the fluorine-containing substances that contain such metal ions or metal fine particles. In addition, metal ions or metal particles covered with aggregates of fluorine-containing substances (metal ions or metal particles bound within fluorine-containing substances) have a reduced ability to be dissolved and cleaned with acids or alkalis. However, cleaning with a fluorine-containing cleaner (described below) removes the fluorine-containing substances protecting the metal ions or metal particles, thereby enhancing the ability to dissolve and clean with acids or alkalis the metal ions or metal particles. That is, by adding washing with an acid or alkali as a post-treatment of washing with a fluorine-containing cleaner, it is possible to obtain not only fluorine-containing substances and fluorine-containing substance aggregates but also resin pellets in which the metal ions or metal fine particles are reduced, and a fluororesin molded product made of the pellets in which both the fluorine-containing substances and the metal ions or metal fine particles are reduced.

[0017] In the present invention, as the fluorine-containing extractant used to dissolve and extract the fluorine-containing substance contained or attached to the resin pellet, various fluorine-containing solvents can be used as long as they can dissolve the fluorine-containing substance contained or attached to the resin pellet. As such a fluorine-containing extractant, at least one fluorine-containing extractant selected from hydrofluorocarbons, perfluorocarbons, fluorine-containing ethers, etc. can be exemplified, but it is preferable that the fluorine-containing extractant used for measuring the evaporation residue does not leave impurity components (intentionally added components) contained in the fluorine-containing extractant in the evaporation residue. Even if the fluorine-containing substance can be dissolved, if the impurity components contained in the fluorine-containing extractant remain as the evaporation residue, for example, in the case of propylene glycol methyl ether acetate (PGMEA), etc., the impurity components (antioxidants) added to PGMEA remain as the evaporation residue, which is not preferable. From this viewpoint, the fluorine-containing extractant used in the evaporation residue measurement of the resin pellets of the present invention is preferably 1,1,1,2,3,4,4,5,5,5-decafluoropentane, 1,1,1,2,3,3,4,5,5,5-decafluoropentane, 1,1,1,2,3,3,4,4,5,5,5-decafluoropentane, 1,1,2,3,3,4,4,5,5,5-decafluoropentane, 1,1,2,2,3,4,4,5,5,5-decafluoropentane, It is preferable to use decafluoropentane such as 1,1,2,2,3,3,4,4,5,5-decafluoropentane, 1,2,2,3,3,4,4,5,5,5-decafluoropentane, 1,1,1,3,3,4,4,5,5,5-decafluoropentane, and 1,1,1,2,2,4,4,5,5,5-decafluoropentane, and it is more preferable to use 1,1,1,2,3,4,4,5,5,5-decafluoropentane.

[0018] The fluorine-containing extractant can be appropriately selected depending on the type of fluorine-containing substance to be dissolved, and it is preferable that the resin pellet itself is not dissolved. It is preferable that such a fluorine-containing extractant has a large boiling point difference with the fluorine-containing substance, and more preferably the boiling point difference is 10°C or more. That is, as described above, the fluorine-containing substance contained in or attached to the resin pellet starts to decompose at about 150°C, so when the boiling point of the fluorine-containing extractant is close to 150°C, the decomposition of the fluorine-containing substance starts, and the evaporation residue of the fluorine-containing substance decreases, making quantitative analysis difficult. Specifically, the fluorine-containing extractant is preferably in a gaseous or liquid state at room temperature (20 to 30°C) and has a boiling point that does not destroy the molecular structure of the fluorine-containing substance, and has a boiling point of 0 to 120°C, preferably 0 to 70°C, more preferably 20 to 70°C. In addition, from the viewpoint of handling, it is preferable that the boiling point is 20°C or more higher than room temperature (20 to 30°C).

[0019] When measuring the evaporation residue, it is preferable to immerse the resin pellets in the fluorine-containing extractant so that the mixing ratio of the resin pellets to the fluorine-containing extractant (fluorine-containing extractant / resin pellets) is 2.0 to 2.5 by weight. The resin pellets are immersed in the fluorine-containing extractant and allowed to stand at 60±2°C for 20 hours, after which the resin pellets are separated from the fluorine-containing extractant (extraction liquid) in which the fluorine-containing substances have been extracted, and the extraction liquid is evaporated to dryness. An evaporator is preferably used for the evaporation to dryness, and an electronic balance is preferably used for quantifying the evaporation residue. The particle size and number of the nano-sized particles (foreign fine particles) can be measured, for example, by a particle counter (liquid particle counter), a wafer surface defect inspection device, a total reflection X-ray fluorescence analyzer (TXRF), or the like. The evaporation residue of the resin pellet of the present invention is quantifiable because extremely small amounts of fluorine-containing substances are concentrated through the evaporation and drying process. As a result, it becomes possible to determine whether or not fluorine-containing substances, which are causative substances for forming nano-sized particles (foreign fine particles) that adhere to the wafer surface during the semiconductor manufacturing process and cause defects in the circuit pattern of fine semiconductor devices, are contained in or adhered to the resin pellet, and it also becomes possible to predict the amount of fluorine-containing substances remaining on the wafer.

[0020] (Pellet shape) The resin pellets of the present invention are made of a resin containing at least one selected from homopolymers and copolymers of tetrafluoroethylene, and are used as a molding material obtained by processing the resin into granules (pellets) to improve handling properties. The average particle size of the resin pellets is preferably 0.4 to 5.0 mm, but is not limited thereto. The resin pellets in the above average particle size range include pellets having an average particle size of less than 0.4 to 1 mm, called mini pellets, or pellets having an average particle size of 1.0 to 5.0 mm, and pellets having an appropriate average particle size depending on the application can be appropriately used as the molding material.

[0021] (TFE homopolymer) The homopolymer of tetrafluoroethylene constituting the resin pellet of the present invention may be PTFE, which is a homopolymer of tetrafluoroethylene (TFE), modified PTFE having no thermal melting property modified with at least one monomer copolymerizable with tetrafluoroethylene (TFE) within a range not impairing the properties of PTFE, and a mixture of PTFE and at least one modified PTFE. The monomer of the modified PTFE may be ethene, propene, isobutylene, chloroethene, dichloroethene, fluoroethene, difluoroethene, perfluorobutylethylene (3,3,4,4,5,5,6,6,6,-nonafluoro-1-hexene), chlorotrifluoroethene, perfluoroalkene having 3 or more carbon atoms, perfluoro(alkyl vinyl ether), etc.

[0022] For example, copolymers of TFE and a very small amount of monomer other than TFE described in International Publication No. 2007 / 119829 can be mentioned, more specifically, copolymers of tetrafluoroethylene and at least one monomer selected from hexafluoropropylene, perfluoro(alkyl vinyl ether), fluoroalkylethylene, chlorotrifluoroethylene, vinylidene fluoride, vinyl fluoride, and ethylene at 0.005 to 1 mol%, preferably 0.01 to 0.1 mol%, more preferably 0.01 to 0.05 mol%, which do not have melt moldability, can be mentioned. Among them, fluorine-containing monomers are preferred, and more preferably, perfluoroalkene having 3 to 6 carbon atoms, perfluoro(alkyl vinyl ether) having 1 to 6 carbon atoms in the alkyl group, etc. can be mentioned. The tetrafluoroethylene homopolymer can be produced by a known method such as solution polymerization, emulsion polymerization, or suspension polymerization.

[0023] (TFE copolymer) The copolymer of tetrafluoroethylene constituting the resin pellet of the present invention is a copolymer of tetrafluoroethylene (TFE) and 1 mol % or more of a monomer copolymerizable with tetrafluoroethylene (TFE). The copolymer of tetrafluoroethylene is a copolymer that melts at a temperature equal to or higher than the melting point and exhibits fluidity (thermal melting property), or a composition containing the copolymer, and examples of the copolymer include copolymers of unsaturated fluorinated hydrocarbons, unsaturated fluorinated chlorinated hydrocarbons, ether group-containing unsaturated fluorinated hydrocarbons, and the like, or thermal melting fluororesins such as copolymers of these unsaturated fluorinated hydrocarbons and ethylene.

[0024] Examples of the copolymer include a copolymer containing tetrafluoroethylene and 1 to 60 mol % or less of at least one comonomer, such as a copolymer with at least one monomer selected from perfluoroalkenes having 3 or more carbon atoms and fluoroalkoxytrifluoroethylenes (preferably perfluoro(alkyl vinyl ethers) (PAVEs) (wherein the alkyl group is a linear or branched alkyl group having 1 to 5 carbon atoms)), or a copolymer of these monomers and ethylene.

[0025] Preferred copolymers include TFE / hexafluoropropylene (HFP) copolymers (FEP), TFE / perfluoro(alkyl vinyl ether) (PAVE) copolymers (PFA), ethylene / TFE copolymers (ETFE), TFE / HFP / PAVE copolymers, TFE / HFP / vinylidene fluoride copolymers (THV), TFE / ethylene / perfluorodimethyldioxole copolymers, and TFE / CF 2 =CFOCF 2 CF(CF 3 )OCF 2 CF 2 SO 2 F copolymer, or a mixture of these copolymers, and more preferably at least one copolymer selected from TFE / perfluoro(methyl vinyl ether) (PMVE) copolymer, TFE / perfluoro(ethyl vinyl ether) (PEVE) copolymer, TFE / perfluoro(propyl vinyl ether) (PPVE) copolymer, and TFE / perfluoro(butenyl vinyl ether) copolymer. The content of PAVE in these copolymers is preferably 1 to 30 mol %, more preferably 1 to 20 mol %, and the content of hexafluoropropylene in FEP is preferably 1 to 10 mol %. In addition, to suppress the generation of thermal decomposition products, -CF 2 CH 2 OH, -CONH 2 and -COF, etc., into the thermally stable -CF 3 It is also possible to use copolymers that have been converted to terminal groups (fluorinated) to minimize the elution of impurities.

[0026] The tetrafluoroethylene copolymer is preferably a copolymer having a melt flow rate (MFR) of about 1 to 100 g / 10 min at 372° C. according to ASTM D-1238. The melt flow rate (MFR) can be selected depending on the molding method, and for example, in melt molding such as melt extrusion molding and injection molding, it is desirable that the MFR is 1 to 100 g / 10 min, preferably 1 to 50 g / 10 min, and more preferably 1 to 20 g / 10 min.

[0027] The copolymer of tetrafluoroethylene may be used alone or in the form of a mixture of two or more of these copolymers. Also included are mixtures of at least two or more of the same type of copolymers that are different in monomer type, monomer content, molecular weight (weight average molecular weight or number average molecular weight), molecular weight distribution, melting point, melt flow rate (MFR), etc., or different mechanical properties, etc. For example, a mixture of PFAs or FEPs may be used. Such a tetrafluoroethylene copolymer can be produced by a known method such as solution polymerization, emulsion polymerization, or suspension polymerization. The melting point of the tetrafluoroethylene copolymer is not limited, but is desirably 150°C or higher, preferably 150°C to 340°C.

[0028] The resin of the present invention containing at least one selected from the group consisting of homopolymers and copolymers of tetrafluoroethylene may be a mixture of the above-mentioned tetrafluoroethylene polymer not having melt moldability and a tetrafluoroethylene copolymer having melt moldability.

[0029] (Manufacturing method of resin pellets) The resin pellets of the present invention can be produced by forming at least one resin selected from the above-mentioned homopolymers and copolymers of tetrafluoroethylene into granules (pellets) and then cleaning the molded product with a fluorine-containing cleaner. The molding method for obtaining resin pellets is not particularly limited, and any conventionally known method can be used. For example, pellets can be obtained by melt-kneading the resin using a single-screw extruder, a twin-screw extruder, or a tandem extruder, extruding the mixture, and cutting the mixture to a predetermined length using a melt-cut method or a strand method. As described above, the average particle size of the resin pellets is preferably in the range of 0.4 to 5.0 mm.

[0030] In the resin pellets of the present invention, by washing the obtained resin pellets with a fluorine-containing detergent, it is possible to reduce the fluorine-containing substances contained in or attached to the resin pellets to a range in which the above-mentioned evaporation residue is as close to zero as possible. The resin pellets are washed by contacting them with a fluorine-containing cleaner described below. For example, the resin pellets may be immersed in (and stirred with) the fluorine-containing cleaner, or the fluorine-containing cleaner may be made to flow over the surfaces of the resin pellets (the fluorine-containing cleaner of the present invention may be circulated using a pump or the like). From an economical viewpoint, the cleaning treatment is preferably carried out at a temperature between room temperature and a temperature at which the saturated vapor pressure is about 70 kPa, or at a temperature approximately 10° C. lower than the boiling point of the fluorine-containing solvent used. The mixing ratio of the fluorine-containing cleaner to the resin pellets used in the cleaning treatment (fluorine-containing cleaner / resin pellets (weight ratio)) is arbitrary, but is preferably 0.01 or more, more preferably 0.1 or more.

[0031] The fluorine-containing cleaner used for cleaning the resin pellets is a solvent for dissolving causative substances (fluorine-containing substances) that cause nano-sized particles contained in or attached to the resin pellets, and is made of a fluorine-containing solvent. The fluorine-containing cleaner is preferably at least one selected from hydrofluorocarbons, perfluorocarbons, and fluorine-containing ethers.

[0032] The hydrofluorocarbon is a saturated or unsaturated compound having 3 to 9 carbon atoms, preferably 4 to 8 carbon atoms, containing only carbon, fluorine and hydrogen atoms, in which at least 50% of all atoms bonded to carbon atoms are fluorine atoms. For example, there are saturated hydrocarbons such as tridecafluorooctane, pentadecafluoroheptane, decafluoropentane, pentafluorobutane, pentafluoropropane, and heptafluorocyclopentane, or compounds represented by the following general formula (I): R f -CH 2 CH=CHCH 2 -R f (I) (In the formula, R f is a perfluoroalkyl group. Examples of unsaturated hydrocarbons include hydrofluoroolefins (HFOs) represented by the following formula:

[0033] As for saturated hydrocarbons, 5 H 2 F 10 It is preferable to use decafluoropentane represented by the formula: Decafluoropentane has a plurality of structural isomers, and a mixture of these isomers may be used. More preferably, it may be 1,1,1,2,3,4,4,5,5,5-decafluoropentane, or a mixture of 1,1,1,2,3,4,4,5,5,5-decafluoropentane and other decafluoropentane isomers. The unsaturated hydrocarbon may preferably be 2,3,3,3-tetrafluoro-1-propene (HFO-1234yf), an isomer thereof, or 1,1,1,4,4,4-hexafluoro-2-butene, an isomer thereof, or a mixture of said isomers. More preferably, the 1,1,1,4,4,4-hexafluoro-2-butene is (Z)-HFO-1336mzzm.

[0034] The perfluorocarbon is a saturated or unsaturated compound having 1 to 9 carbon atoms and containing only carbon and fluorine atoms, and includes fully fluorinated cycloalkanes such as tetrafluoromethane, hexafluoroethane, octafluoropropane, decafluorobutane, dodecafluoropentane, tetradecafluorohexane, octafluorocyclobutane, and perfluoromethylcyclohexane, and further includes compounds represented by the following general formula (II): CF 2 =CFR f (II) (In the formula, R f indicates a perfluoroalkyl group. Examples of the perfluoroolefin include unsaturated hydrocarbons represented by the formula (1), for example, perfluoroheptene. Perfluoroheptene has several isomers, for example, perfluoro-2-heptene, perfluoro-3-heptene, etc., and these may be used alone or in combination.

[0035] The fluorine-containing ether is an ether containing fluorine, and examples thereof include hydrofluoroether (HFE) and perfluoroether (PFE). Examples of hydrofluoroethers (HFEs) include saturated or unsaturated compounds having an ether bond, such as hexafluoroisopropanol, trifluoroethanol, tetrafluoroethanol, pentafluoropropanol, 1,1,1-trifluoroethyl-1,1,2,2-tetrafluoroethyl ether, nonafluorobutyl methyl ether, alkoxyperfluoroalkene, etc. Preferred are hydrofluoroethers having 3 to 8 carbon atoms, such as Novec (registered trademark) 7200, Novec (registered trademark) 7500, and Novec (registered trademark) 7600 manufactured by 3M Japan Ltd.

[0036] Examples of perfluoroethers (PFE) include perfluoro(alkyl)alkyl ethers such as perfluoro(propyl)methyl ether, perfluoro(butyl)methyl ether, perfluoro(hexyl)methyl ether, and perfluoro(butyl)ethyl ether.

[0037] Examples of the alkoxyperfluoroalkene include methoxyperfluoroalkene or ethoxyperfluoroalkene having 5 to 10 carbon atoms, and preferably include methoxyperfluoropentene, methoxyperfluorohexene, methoxyperfluoroheptene, methoxyperfluorooctene, ethoxyperfluoropentene, ethoxyperfluorohexene, ethoxyperfluoroheptene, ethoxyperfluorooctene, and mixtures thereof. Note that, although there are a plurality of structural isomers of alkoxyperfluoroalkene, there is no particular restriction on the structure, and the mixture may be used, and one that meets the purpose of the present invention can be appropriately selected.

[0038] More preferably, methoxyperfluoroheptene, its isomers, or a mixture thereof is exemplified. The structure of methoxyperfluoroheptene is as follows, but any structure may be used. (1)CF 3 (CF 2 ) 2 CF=CFCF(OCH 3 )CF 3 (2)CF 3 CF 2 CF=CF(CF 2 ) 2 (OCH 3 )CF 3 (3)CF 3 CF 2 CF=CFCF(OCH 3 )CF 2 CF 3 (4)CF 3 CF=CFCF(OCH 3 )(CF 2 ) 2CF 3 (5)CF 3 CF=CFCF 2 CF(OCH 3 )CF 2 CF 3 (6)CF 3 CF 2 CF=C(OCH 3 )(CF 2 ) 2 CF 3 (7)CF 3 CF 2 C(OCH 3 )=CFCF 2 CF 2 CF 3

[0039] An example of a methoxyperfluoroheptene that can be suitably used is Opteon (registered trademark) SF10 manufactured by Mitsui-Chemours Fluoroproducts Co., Ltd.

[0040] The fluorine-containing cleaning agent can be appropriately selected according to the type of fluorine-containing substance to be dissolved, similarly to the above-mentioned fluorine-containing extractant, and preferably has a large boiling point difference with the fluorine-containing substance, more preferably a boiling point difference of 10° C. or more. Specifically, the fluorine-containing cleaning agent is preferably in a gaseous or liquid state at room temperature (20 to 30° C.) and has a boiling point that does not destroy the molecular structure of the fluorine-containing substance, and it is desirable that the boiling point is 0 to 120° C., preferably 0 to 70° C., more preferably 20 to 70° C. In addition, from the viewpoint of handling, it is desirable that the boiling point is 20° C. or more higher than room temperature (20 to 30° C.).

[0041] In addition, it is preferable that the fluorine-containing cleaning agent used for cleaning the resin pellets does not leave impurity components (intentionally added components) of the fluorine-containing cleaning agent on the resin pellets. As with the fluorine-containing extractant used in the measurement of the evaporation residue described above, 1,1,1,2,3,4,4,5,5,5-decafluoropentane, 1,1,1,2,3,3,4,4,5,5,5-decafluoropentane, 1,1,1,2,3,3,4,4,5,5,5-decafluoropentane, 1,1,2,3,3,4,4,5,5,5-decafluoropentane, It is preferable to use decafluoropentanes such as pentane, 1,1,2,2,3,4,4,5,5,5-decafluoropentane, 1,1,2,2,3,3,4,4,5,5-decafluoropentane, 1,2,2,3,3,4,4,5,5,5-decafluoropentane, 1,1,1,3,3,4,4,5,5,5-decafluoropentane, and 1,1,1,2,2,4,4,5,5,5-decafluoropentane, and it is more preferable to use 1,1,1,2,3,4,4,5,5,5-decafluoropentane.

[0042] The resin pellets washed with the fluorine-containing cleaner are separated from the fluorine-containing cleaner, dried at 270±5° C. for 20 hours, and then cooled in a furnace to obtain the resin pellets of the present invention. The melt flow rate of the washed resin pellets is equivalent to that of the resin pellets before washing, so that the molded product can be used without changing the molding conditions.

[0043] In the present invention, furthermore, washing with an acid or alkali may be added as a post-treatment of washing with the above-mentioned fluorine-containing cleaner, as described above, which not only reduces the amount of fluorine-containing substances and their aggregates but also makes it possible to obtain resin pellets with reduced amounts of metal ions or metal fine particles.

[0044] (molded product) The molded article of the present invention is a molded article made of the resin pellets of the present invention described above, and the fluorine-containing substance contained in or attached to the molded article is dissolved and extracted in a fluorine-containing extractant, and the extract is evaporated to dryness, and the evaporation residue is 20×10 -6 mg / mm 2 It is preferable that the molded article is one which is as follows: It is desirable for the evaporation residue of molded products to be as close to zero as possible. -6 mg / mm 2 Preferably, 0 to 10×10 -6 mg / mm 2 More preferably, the range is 0 to 1.0 × 10 -6 mg / mm 2 In the molded article of the present invention having an evaporation residue in this range, the generation of causative substances (fluorine-containing substances) that cause the generation of the particles is suppressed, and therefore the molded article can be suitably used as a molded article having high cleanliness for use in the manufacture of semiconductors. The evaporation residue of the fluorine-containing material contained in or attached to the molded article can be measured in the same manner as in the case of the resin pellets described above. However, it is preferable to bring the surface of the molded article into contact with a fluorine-containing extractant depending on the shape of the molded article. For example, in the case of a molded article having a hollow portion such as a tube or a bottle, the extract can be collected by sealing the fluorine-containing extractant inside the tube or bottle.

[0045] The molded article of the present invention is preferably a molded article used as a molded article for liquid transport, a molded article for contact with liquid, etc. Specifically, the molded article for liquid transport is a molded article used in liquid transport devices such as tubes, piping (pipes), piping joints (fittings), gaskets, O-rings, pumps, valves, regulators, filter housings, etc., and the molded article for liquid contact is a molded article used in tools and devices that come into contact with liquids other than those for liquid transport, such as containers (bottles, caps, inner lids) such as transport containers and storage containers, wafer carriers, films, etc. The molded article of the present invention is preferably a molded article having a hollow portion. Examples of such molded articles having a hollow portion include bottles, tubes, pipes, and piping fittings.

[0046] The molding method of the molded article of the present invention is not particularly limited, and the above-mentioned resin pellets of the present invention can be molded by a conventionally known molding method. Examples of the molding method include compression molding, paste extrusion molding, melt compression molding, melt extrusion molding, injection molding, transfer molding, blow molding, rotational molding, lining molding, and film molding.

[0047] Since the molded article of the present invention is molded using the resin pellets of the present invention, the evaporation residue described above is 20×10 -6 mg / mm 2 Although the concentration of the fluorine-containing detergent is reduced below, the molded product may be subjected to a cleaning treatment using the above-mentioned fluorine-containing detergent, which can further improve the cleanliness of the molded product. The cleaning treatment may be carried out in the same manner as in the cleaning treatment of resin pellets described above, by contacting, immersing (and stirring) or shaking the molded article in a fluorine-containing cleaner, or by flowing the fluorine-containing cleaner over the surface of the molded article (by circulating the fluorine-containing cleaner using a pump or the like). The washing treatment can be carried out under the same conditions as those for the washing treatment of the resin pellets described above. Furthermore, as described above, the fluorine-containing substances protecting the metal ions or metal fine particles are also removed. Therefore, by adding washing with an acid or alkali as a post-treatment after cleaning with the fluorine-containing cleaner of the present invention, it is possible to obtain resin pellets in which not only the fluorine-containing substances but also the metal ions or metal fine particles are reduced, and a fluororesin molded product made of the pellets in which both the fluorine-containing substances and the metal ions or metal fine particles are reduced.

[0048] The fluorine-containing cleaner used in the present invention, so long as it can dissolve and extract adherent or contained matter in resin pellets or molded articles, can also be used on resin pellets made of at least one type selected from the above-mentioned tetrafluoroethylene homopolymers or copolymers, or molded articles made thereof, as well as resin pellets made of other engineering plastics, such as polyethylene, polypropylene, vinyl chloride, phenolic resin, silicone resin, etc., and molded articles made of these resin pellets. EXAMPLES

[0049] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The materials, cleaning treatments, and measurement methods used in the examples are as follows.

[0050] (material) 1.Resin pellets (1) PFA pellets (1) (MFR 2g / 10min, melting point 310℃) (2) PFA pellets (2) (MFR 5g / 10min, melting point 263℃)

[0051] 2. Fluorine-containing extractants (1) 1,1,1,2,3,4,4,5,5,5-Decafluoropentane (boiling point 55°C) (represented as "XF" in the table)

[0052] 3. Fluorine-containing cleaning agents (1) Methoxyperfluoroheptene (boiling point 110°C) (referred to as "SF10" in the table) (2) Perfluoroheptene (boiling point 72°C) (referred to as "PFH" in the table) (3) 1,1,1,2,3,4,4,5,5,5-Decafluoropentane (boiling point 55°C) (represented as "XF" in the table)

[0053] 4. Molded products made from resin pellets (1) Tube Resin pellets shown in Table 1 were used, and the resin pellets were heated to or above their melting point and extruded to obtain an unstretched tube having an outer diameter of 6.35 mm, an inner diameter of 4.35 mm and a length of 50 m. (2) Bottle Resin pellets shown in Table 1 were used, and the resin pellets were heated to above their melting point and blow molded to obtain 100 ml bottles.

[0054] 5. Cleaning process (1) Washing of resin pellets A mixture of the fluorine-containing cleaning agent and the resin pellets in the weight ratio (fluorine-containing cleaning agent / resin pellets) shown in Table 1 or Table 3 was heated in an oven for 2 hours at the cleaning temperature shown in Table 1 or Table 3, and then the resin pellets and the fluorine-containing cleaning agent were separated. The separated resin pellets were dried for 20 hours at the drying temperature shown in Table 1 or Table 3, and then cooled in an oven to room temperature (20 to 30°C). (2) Cleaning of molded products (tubes) A fluorine-containing cleaner shown in Table 2 was inserted into 50 m of the unstretched tube by folding both ends by 100 mm each and sealing them with a plastic band. The tube was then left to stand in an oven at 60°C for 20 hours, and then dried at room temperature (20 to 30°C) for 5 to 10 minutes using nitrogen gas passed through a 0.003 μm in-line filter. (3) Cleaning of molded products (bottles) Into the 100 ml bottle, 130 g of a fluorine-containing cleaner shown in Table 2 was sealed using a cleaned PFA lid, and the bottle was left to stand at room temperature for 168 hours, after which the fluorine-containing cleaner was discharged and the bottle was dried at room temperature (20 to 30°C) for 24 hours or more in a clean room of cleanliness class 100 or less.

[0055] (Measurement method) 6. Measurement of evaporation residue (1) Evaporation residue of 1,1,1,2,3,4,4,5,5,5-decafluoropentane (XF) (blank) 500 g or 130 g of 1,1,1,2,3,4,4,5,5,5-decafluoropentane (XF) was placed in a recovery flask (300 ml) and each was evaporated to dryness using an evaporator. Each evaporation residue was weighed using an electronic balance to determine the amount of evaporation residue (mg) of 1,1,1,2,3,4,4,5,5,5-decafluoropentane. (2) Resin pellet evaporation residue The resin pellets were immersed in 1,1,1,2,3,4,4,5,5,5-decafluoropentane (XF) and allowed to stand at 60°C for 20 hours, after which the 1,1,1,2,3,4,4,5,5,5-decafluoropentane (XF) was filtered using a polypropylene filter membrane with a membrane aperture of 0.2 μm to remove the PFA fine powder contained in or attached to the resin pellets and obtain an extract. 500 g of the extract was evaporated to dryness using an evaporator, and the evaporation residue was weighed using an electronic balance, from which the amount of evaporation residue in 500 g of 1,1,1,2,3,4,4,5,5,5-decafluoropentane in (1) above was subtracted to obtain the evaporation residue per unit surface area of ​​the pellet (mg / mm 2 The surface area of ​​the pellets was calculated in accordance with SEMI C90-1015.

[0056] (3) Evaporation residue of molded product (unstretched tube) 1,1,1,2,3,4,4,5,5,5-decafluoropentane (XF) was folded at both ends by 100 mm each and sealed in 50 m of the molded product (unstretched tube) using a plastic band, and the mixture was allowed to stand at 60°C for 20 hours, after which it was extracted using nitrogen gas to obtain an extract. 500 g of the extract was evaporated to dryness using an evaporator, and the evaporation residue was weighed using an electronic balance, from which the amount of evaporation residue in 500 g of 1,1,1,2,3,4,4,5,5,5-decafluoropentane in (1) above was subtracted to obtain the evaporation residue (mg / mm2) per inner surface area of ​​the unstretched tube. 2 ) was sought.

[0057] (4) Evaporation residue of molded products (bottles) 130 g of 1,1,1,2,3,4,4,5,5,5-decafluoropentane (XF) was placed in the bottle (100 ml) and allowed to stand at room temperature for 168 hours to obtain an extract. 130 g of the extract was evaporated to dryness using an evaporator, and the evaporation residue was weighed using an electronic balance. The amount of the evaporation residue per 130 g of 1,1,1,2,3,4,4,5,5,5-decafluoropentane in (1) above was subtracted from the weight to obtain the evaporation residue per inner surface area of ​​the bottle (mg / mm 2 ) was sought.

[0058] 7.Melt Flow Rate (MFR) Using a melt indexer (manufactured by Toyo Seiki) equipped with a corrosion-resistant cylinder, die, and piston conforming to ASTM D-1238-95, 5 g of the sample powder was filled into a cylinder maintained at 372±1°C and held for 5 minutes, and then extruded through the die orifice under a 5 kg load (piston and weight). The extrusion rate at this time (g / 10 min) was calculated as the MFR.

[0059] (Examples 1 to 6) After the resin pellets were washed under the conditions shown in Table 1, the evaporation residue of the resin pellets was determined. The results are shown in Table 1.

[0060] Comparative Example 1 The evaporation residue of the resin pellets shown in Table 1 was determined in the same manner as in Example 1, except that the washing treatment was not carried out. The results are shown in Table 1.

[0061] (Examples 7 to 10) The evaporation residue was measured for molded articles (tubes) made of the resin pellets of Examples 1, 3, 4, and 6 shown in Table 2. The results are shown in Table 2.

[0062] (Examples 11 to 14) Molded articles (tubes) made of the resin pellets of Examples 1, 3, 4, and 6 shown in Table 2 were washed, and the evaporation residue of the molded articles (tubes) was determined. The results are shown in Table 2.

[0063] Example 15 A molded article (bottle) made of the resin pellets of Example 3 shown in Table 2 was washed, and then the evaporation residue of the molded article (bottle) was determined. The results are shown in Table 2.

[0064] Comparative Example 2 Except for using the resin pellets of Comparative Example 1, the evaporation residue of a molded article (tube) made of the pellets of Comparative Example 1 was determined in the same manner as in Example 7. The results are shown in Table 2.

[0065] Comparative Example 3 Except for using the resin pellets of Comparative Example 1, the evaporation residue of a molded article (tube) made of the pellets of Comparative Example 1 was determined in the same manner as in Example 11. The results are shown in Table 2.

[0066] Comparative Example 4 The evaporation residue was measured for a molded article (bottle) made from the pellets of Comparative Example 1. The results are shown in Table 2.

[0067] Comparative Example 5 Except for using the resin pellets of Comparative Example 1, the evaporation residue of a molded article (bottle) made of the pellets of Comparative Example 1 was determined in the same manner as in Example 15. The results are shown in Table 2.

[0068] (Examples 16 and 17) After the resin pellets were washed under the conditions shown in Table 3, the evaporation residue of the resin pellets was determined. The results are shown in Table 3.

[0069] Comparative Example 6 The evaporation residue of the resin pellets was determined in the same manner as in Example 16, except that the washing treatment was not carried out. The results are shown in Table 3.

[0070] [Table 1]

[0071] [Table 2]

[0072] [Table 3] [Industrial Applicability]

[0073] The resin pellets of the present invention can be suitably used as a molding material for molding a molded article that requires high cleanliness and is used in the production of semiconductors. The molded article of the present invention can also be suitably used as a molded article for transferring liquid or a molded article for contacting liquid, which has high cleanliness and is used in the production of semiconductors.

Claims

1. A resin pellet containing at least one selected from tetrafluoroethylene copolymers, the pellet being washed with a fluorine-containing cleaning agent, and a fluorine-containing substance contained in or attached to the pellet being dissolved and extracted in a fluorine-containing extractant, the extract being filtered using a polypropylene filter membrane having a membrane diameter of 0.2 μm, and the evaporation residue after evaporating and drying is 0 to 1.0 × 10 －６ mg / mm ２ is in the range The tetrafluoroethylene (TFE) copolymer is a copolymer of tetrafluoroethylene (TFE) and 1 to 60 mol % of a comonomer, and is at least one selected from the group consisting of TFE / hexafluoropropylene (HFP) copolymer (FEP), TFE / perfluoro(alkyl vinyl ether) (PAVE) copolymer (PFA), ethylene / TFE copolymer (ETFE), TFE / HFP / PAVE copolymer, TFE / HFP / vinylidene fluoride copolymer (THV), TFE / ethylene / perfluorodimethyldioxole copolymer, TFE / CF 2 ═CFOCF 2 CF(CF 3 )OCF 2 CF 2 SO 2 F copolymer, and mixtures of these copolymers; The fluorine-containing cleaning agent is at least one selected from perfluoroolefins and alkoxyperfluoroalkenes, The resin pellets are characterized in that the fluorine-containing extractant is decafluoropentane.

2. The tetrafluoroethylene (TFE) copolymer is a copolymer of tetrafluoroethylene (TFE) and 1 to 30 mol% perfluoro(alkyl vinyl ether) (PAVE), and is at least one selected from TFE / perfluoro(methyl vinyl ether) (PMVE) copolymer, TFE / perfluoro(ethyl vinyl ether) (PEVE) copolymer, TFE / perfluoro(propyl vinyl ether) (PPVE) copolymer, and TFE / perfluoro(butenyl vinyl ether) copolymer. The resin pellet according to claim 1.

3. The resin pellet according to claim 1 or 2, wherein the fluorine-containing cleaning agent is a perfluoroolefin or an alkoxyperfluoroalkene having a boiling point in the range of 0 to 120°C and a boiling point difference of 10°C or more from that of the fluorine-containing substance.

4. A method for producing resin pellets as described in any of claims 1 to 3, characterized in that resin pellets containing at least one tetrafluoroethylene copolymer selected from tetrafluoroethylene (TFE) and 1 to 60 mol% of a comonomer, the tetrafluoroethylene copolymer being at least one selected from TFE / hexafluoropropylene (HFP) copolymer (FEP), TFE / perfluoro(alkyl vinyl ether) (PAVE) copolymer (PFA), ethylene / TFE copolymer (ETFE), TFE / HFP / PAVE copolymer, TFE / HFP / vinylidene fluoride copolymer (THV), TFE / ethylene / perfluorodimethyldioxole copolymer, TFE / CF2=CFOCF2CF(CF3)OCF2CF2SO2F copolymer, or mixtures of these copolymers, are washed with a fluorine-containing cleaning agent which is at least one selected from perfluoroolefins or alkoxyperfluoroalkene.

5. 5. The method for producing resin pellets according to claim 4, further comprising washing with an acid or alkaline solution after washing with the fluorine-containing detergent.

6. A molded article comprising the resin pellets according to any one of claims 1 to 3.

7. The fluorine-containing substance contained in or attached to the molded article is dissolved and extracted in a fluorine-containing extractant, and the extract is evaporated to dryness, so that the evaporation residue is 0 to 1.0 × 10 －６ mg / mm ２ The molded article according to claim 6, wherein the range is

8. 8. The molded article according to claim 6, which is a molded article having a hollow portion.

9. 9. The molded article according to claim 6, which is washed with a fluorine-containing detergent, or which is washed with a fluorine-containing detergent and then washed with an acid or alkaline solution.

10. 10. The molded article according to claim 9, wherein the fluorine-containing detergent is at least one selected from the group consisting of hydrofluorocarbons, perfluorocarbons, and fluorine-containing ethers.

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