Method for producing molded article and molded article
阅读说明：本技术 成型品的制造方法和成型品 (Method for producing molded article and molded article ) 是由 今村均 向井惠吏 近藤昌宏 于 2019-07-10 设计创作，主要内容包括：本发明提供一种成型品的制造方法和成型品,该制造方法能够制造出颗粒产生量降低的成型品。本发明的成型品的制造方法包括下述工序：制备工序,将四氟乙烯/全氟(烷基乙烯基醚)共聚物在温度T1(℃)成型来制备成型材料；以及成型工序,将上述成型材料在温度T2(℃)挤出成型来得到成型品,温度T1和温度T2满足20≤T1-T2≤80的关系。(The invention provides a method for producing a molded article and a molded article, wherein the method can produce a molded article with reduced particle generation. The method for producing a molded article of the present invention comprises the steps of: a production step of molding a tetrafluoroethylene/perfluoro (alkyl vinyl ether) copolymer at a temperature T1 (DEG C) to produce a molding material; and a molding step of obtaining a molded article by extrusion molding the molding material at a temperature T2 (DEG C), wherein the temperature T1 and the temperature T2 satisfy a relationship of 20 to T1 and T2 to 80.)
1. A method for producing a molded article, comprising the steps of:
a production process of molding a tetrafluoroethylene/perfluoro (alkyl vinyl ether) copolymer at a temperature T1 (. degree.C.) to produce a molding material, and
a molding step of obtaining a molded article by extrusion molding the molding material at a temperature T2 (DEG C),
the temperature T1 and the temperature T2 satisfy the relationship of 20 ≦ T1-T2 ≦ 80.
2. The production method according to claim 1, wherein the temperature T1 (DEG C) in the production step is 390 ℃ or higher.
3. The production process according to claim 1 or 2, wherein the tetrafluoroethylene/perfluoro (alkyl vinyl ether) copolymer used in the production step has a melting point of 295 ℃ or higher.
4. The production process according to any one of claims 1 to 3, wherein the content of the perfluoro (alkyl vinyl ether) unit in the tetrafluoroethylene/perfluoro (alkyl vinyl ether) copolymer used in the production step is 3.5 to 7.0% by mass.
5. The production method according to any one of claims 1 to 4, wherein in the production step, the molding material is produced by extrusion molding.
6. The production method according to any one of claims 1 to 5, wherein the molding material obtained in the production step is a pellet.
7. The production method according to any one of claims 1 to 6, wherein the molded article obtained in the molding step is a tube.
8. A molded article comprising a tetrafluoroethylene/perfluoro (alkyl vinyl ether) copolymer having a melting point of 295 ℃ or higher, wherein the number of particles having a diameter of 30nm or more dispersed in isopropanol when the molded article is brought into contact with isopropanol is 700 particles/ml or less.
9. The molded article of claim 8, wherein the molded article is a tube.
Technical Field
The present invention relates to a method for producing a molded article and a molded article.
Background
Patent document 1 describes a stabilized fluoropolymer production method characterized in that, prior to stabilization of a fluoropolymer obtained by melt-kneading a melt-processable fluoropolymer having an unstable group in a kneader including a stabilization treatment region for stabilizing the fluoropolymer in the presence of water and oxygen, a melting region is disposed as a region prior to the stabilization treatment region, the melting region is melt-kneaded for the fluoropolymer at a temperature and for a time sufficient to decompose or volatilize low molecular weight substances in the fluoropolymer, the low molecular weight substances are decomposed and/or volatilized in the melting region, and the fluoropolymer is discharged out of the kneader prior to the stabilization treatment region.
Disclosure of Invention
Problems to be solved by the invention
The purpose of the present invention is to provide a method for producing a molded article, which can produce a molded article with a reduced amount of particles generated.
Further, the present invention aims to provide a molded article with a reduced amount of particles generated.
Means for solving the problems
According to the present invention, there is provided a method for producing a molded article, comprising the steps of: a production step of molding a tetrafluoroethylene/perfluoro (alkyl vinyl ether) copolymer at a temperature T1 (DEG C) to produce a molding material; and a molding step of obtaining a molded article by extrusion molding the molding material at a temperature T2 (DEG C), wherein the temperature T1 and the temperature T2 satisfy a relationship of 20 to T1 and T2 to 80.
The temperature T1 (. degree.C.) in the above production step is preferably 390 ℃ or higher.
The melting point of the tetrafluoroethylene/perfluoro (alkyl vinyl ether) copolymer used in the above production step is preferably 295 ℃ or higher.
The content of the perfluoro (alkyl vinyl ether) unit in the tetrafluoroethylene/perfluoro (alkyl vinyl ether) copolymer used in the above-mentioned production step is preferably 3.5 to 7.0 mass%.
In the above-mentioned production step, it is preferable to produce the molding material by extrusion molding.
The molding material obtained in the above-mentioned production step is preferably a pellet.
The molded article obtained in the molding step is preferably a tube.
Further, according to the present invention, there is provided a molded article comprising a tetrafluoroethylene/perfluoro (alkyl vinyl ether) copolymer having a melting point of 295 ℃ or higher, wherein the number of particles having a diameter of 30nm or more dispersed in isopropanol when the copolymer is brought into contact with isopropanol is 700 particles/ml or less.
The molded article of the present invention is preferably a tube.
ADVANTAGEOUS EFFECTS OF INVENTION
According to the present invention, a method for producing a molded article capable of producing a molded article with a reduced amount of particle generation can be provided.
Further, according to the present invention, a molded article with a reduced amount of particle generation can be provided.
Drawings
Fig. 1 is a diagram for explaining a mechanism of adhesion of particles to a tube in a conventional tube forming process.
FIG. 2 is a diagram for explaining an example of the production process.
FIG. 3 is a diagram for explaining a method of measuring the number of particles.
Detailed Description
The following is a detailed description of specific embodiments of the present invention, but the present invention is not limited to the following embodiments.
With the progress of the miniaturization process of semiconductors, it is important to reduce the amount of contaminants from molded articles used in semiconductor devices and reagent supply facilities. For example, japanese patent laid-open No. 2014-222756 has pointed out a problem that particles are generated from a pipe for supplying a reagent and the particles enter into the reagent.
Since a molded article comprising a copolymer containing tetrafluoroethylene units (TFE units) and perfluoro (alkyl vinyl ether) units (PAVE units) (hereinafter referred to as TFE/PAVE copolymer (or PFA)), is excellent in chemical resistance and the like, it is often used in semiconductor devices or reagent supply equipment, and the area in contact with a high-purity reagent is large. However, in the prior art including patent document 1, no study has been made on a method for suppressing generation of particles in a molded article containing a TFE/PAVE copolymer which exhibits a very high melting point depending on a composition and the like.
As a result of intensive studies on the pellet-reducing technique, the present inventors have found that the generation of pellets from a molded article finally obtained can be suppressed to a level that has not been achieved in the past by strictly controlling the temperature at which a TFE/PAVE copolymer is heated in a series of steps for producing a molded article from a raw material.
Further, according to the technical idea obtained by the present inventors, even if the molded article is washed with ultrapure water until no particles are detected, when isopropyl alcohol is brought into contact with the washed molded article, particles are detected in isopropyl alcohol. That is, it has also been found that the number of particles cannot be accurately evaluated by a conventional evaluation method in which a molded article is cleaned with ultrapure water, ultrapure water (cleaning water) is recovered, and particles dispersed in ultrapure water are measured, and the number of particles can be accurately evaluated by a novel evaluation method using isopropyl alcohol.
The production method of the present invention is based on these technical ideas, and is characterized in that in the production method comprising a production step of molding a TFE/PAVE copolymer at a temperature T1 (. degree.C.) to produce a molding material and a molding step of extrusion-molding the molding material at a temperature T2 (. degree.C.) to obtain a molded article, the temperature T1 and the temperature T2 satisfy the relationship of 20. ltoreq. T1-T2. ltoreq.80.
The temperature T1 (. degree.C.) in the above-mentioned production step is a molding temperature at the time of molding the TFE/PAVE copolymer for the purpose of producing a molding material. In the above-described production process, the molding temperature may be set so as to be constant within a range that does not affect molding, or may be changed. When the molding temperature is changed, the molding temperature may be changed so that the temperature T1 and the temperature T2 satisfy the relationship of 20. ltoreq.T 1-T2. ltoreq.80, assuming that the temperature at any point in the above-described production process is T1. That is, the temperature T1 in the production step may be the temperature at any time in the production step, or may be the highest temperature in the production step. The temperature T1 is not the copolymer temperature but the set temperature of the molding machine used for molding.
The temperature T1 is preferably the melting point or softening point of the TFE/PAVE copolymer or higher, more preferably the melting point or higher of the TFE/PAVE copolymer, even more preferably 350 ℃ or higher, even more preferably 370 ℃ or higher, particularly preferably 390 ℃ or higher, and most preferably 400 ℃ or higher, for the reason that a molded article with a further reduced amount of particles can be obtained and the productivity is excellent. The temperature T1 is preferably lower than the thermal decomposition temperature of the TFE/PAVE copolymer, and more preferably 430 ℃ or lower, because a molded article with a further reduced amount of particles can be obtained without damaging the TFE/PAVE copolymer, and the productivity is excellent. In the conventional molding material production process, the advantages of molding a TFE/PAVE copolymer at a relatively high temperature are not known, and therefore the molding temperature is set to a low temperature in consideration of the influence on the TFE/PAVE copolymer, production cost, safety, and the like. However, the present inventors have found that the amount of particles generated tends to be insufficiently suppressed by the conventional method in which the molding temperature is set to a low temperature within a possible range.
The temperature T2 (. degree. C.) in the molding step is a molding temperature at which the molding material is molded. In the molding step, the molding temperature may be set so as to be constant within a range not affecting molding, or may be changed. When the molding temperature is changed, the molding temperature may be changed so that the temperature T1 and the temperature T2 satisfy the relationship of 20. ltoreq.T 1-T2. ltoreq.80, assuming that the temperature at any point in the molding step is T2. That is, the temperature T2 in the molding step may be the temperature at any point in the molding step, or may be the highest temperature in the molding step. The temperature T2 is not the copolymer temperature but the set temperature of the molding machine used for molding.
The temperature T2 is set to a temperature lower than the temperature T1 in such a manner that the inequality 20. ltoreq.T 1-T2. ltoreq.80 is satisfied. That is, in the production method of the present invention, the generation of particles from the finally obtained molded article can be suppressed to a level that has not been achieved in the past by controlling the temperature difference between the temperature T1 and the temperature T2 to be in the range of 20 to 80 ℃. On the other hand, when the conventional method in which the productivity is emphasized and the molding temperature is set to a high possible range in order to increase the extrusion rate is adopted in the molding of the above molded article, the amount of the generated particles cannot be sufficiently suppressed. For the reason that a molded article with a further reduced amount of particle generation can be obtained, the temperature T1 and the temperature T2 preferably satisfy the inequality 30. ltoreq.T 1-T2, more preferably satisfy the inequality 40. ltoreq.T 1-T2, and preferably satisfy the inequality T1-T2. ltoreq.70. Further, it is preferable to increase the temperature difference between T1 and T2 as the size of the molded article to be produced increases.
The reason why a molded article with a reduced amount of particles generated can be produced by strictly controlling the temperature T1 and the temperature T2 is not clear, and is presumed as follows. Fig. 1 is a diagram for explaining a mechanism of adhesion of particles to a tube in a conventional tube forming process. As shown in fig. 1, a TFE/PAVE
On the other hand, it is presumed that, in the production method of the present invention, by strictly controlling the temperature T1 and the temperature T2, even when the TFE/PAVE copolymer is melted in the molding step, a low molecular weight product is not easily produced, and a molded product with a reduced amount of generation of particles can be produced.
In the above-mentioned production step, the molding method for producing the molding material is not particularly limited, and a method capable of molding into a shape suitable for extrusion molding in the above-mentioned molding step is preferable, and an extrusion molding method is more preferable. In the above-described production step, the molding material is produced by extrusion molding, whereby the molding material can be produced with high productivity, and a molded article with a further reduced amount of particles can be obtained.
The shape of the TFE/PAVE copolymer used in the above production process is not particularly limited, but is preferably a particle or powder for the reason of easy production.
The shape of the molding material is not particularly limited, and is preferably a shape suitable for extrusion molding in the molding step. The molding material may be powder, pellet (クラ ム), etc., and an extrusion molding method may be used as a molding method for producing the molding material, and pellet is preferable because it has a shape suitable for extrusion molding in the molding step, and a molded product having excellent productivity and further reduced particle generation amount can be obtained.
The pellet is preferably a substantially cylindrical pellet having a length of 1 to 3mm and a diameter of 0.5 to 3mm, for the reasons of easy production and easy handling. The diameter of the pellet is more preferably 1 to 2 mm.
In the above-mentioned production step, it is particularly preferable to produce pellets as a molding material by extrusion molding because the molding material can be produced with high productivity and a molded article with a further reduced amount of particles can be obtained.
In the above-mentioned production step, when the molding material is produced by extrusion molding, an extruder may be used. The extruder may be a single screw extruder or a twin screw extruder.
FIG. 2 is a diagram for explaining an example of the above-mentioned production process. In the preparation process shown in fig. 2, the
A vent (not shown) may be provided in the
For example, in the case of producing pellets by a thermal cutting method in which a strand immediately after being extruded from a die is cut before cooling or an underwater cutting method in which a strand immediately after being extruded from a die is put into water and cut in water, without using a method for producing pellets by cutting a cooled strand as in the production step shown in fig. 2, a low molecular weight material may not be sufficiently volatilized from a TFE/PAVE copolymer, and therefore, it is preferable to provide a vent hole in a cylinder.
In order to sufficiently volatilize the low-molecular weight material and obtain a molded article with a further reduced amount of generated particles, when the barrel of the extruder is not provided with the vent hole, the low-molecular weight material is usually most easily volatilized from the strand extruded from the die, and therefore it is extremely convenient to set the die temperature to the temperature T1 so as to satisfy the relationship between the temperature T1 and the temperature T2. In addition, in the case where the barrel of the extruder is provided with the vent hole, the low-molecular weight material is most easily volatilized from the vent hole, and therefore, it is preferable that the temperature of the barrel in which the vent hole is located is set to the temperature T1. In addition, when the vacuum pump is connected to the exhaust hole, the temperature T1 can be lowered as compared with the case where the vacuum pump is not connected, for the reason that it is expected that the volatilization of the low molecular weight substance proceeds smoothly. For the above reasons, in the above production process, it is preferable to provide a low molecular weight material volatilization region (a region in which a low molecular weight material is easily volatilized), and control the temperature of the TFE/PAVE copolymer in the low molecular weight material volatilization region to be T1. In the above production step, an extruder having a die set at a temperature T1 or an extruder having a cylinder set at a temperature T1 and a vent hole provided in the cylinder is more preferably used.
In the extruder, a perforated plate (ブレーカープレー ト) may be provided to stabilize the extrusion of the strand. The number of strands extruded from the die is not particularly limited, and may be 5 to 350. The rotation speed of the screw provided in the extruder is not particularly limited, and is set in consideration of the extrusion amount and the extrusion stability, and is, for example, in the range of 5 to 40 rpm.
In order to produce a molded article in which the amount of particles generated is further reduced, it is preferable that the strand extruded from the die has a small diameter, but if the strand is too thin, there is a possibility that a trouble such as strand cutting may occur in the production process. Therefore, the diameter of the strand is preferably 0.5 to 3mm, more preferably 1 to 2 mm.
The molding material obtained in the above-mentioned production step can be molded again at a temperature T1 (. degree. C.) to prepare a molding material. By repeating the above-described production steps, a molded article having a further reduced amount of particles generated can be produced.
In the molding step, the molding material obtained in the preparation step is extrusion molded at a temperature of T2 (. degree. C.) to obtain a molded article. The shape of the molded article is not particularly limited as long as it is a shape that can be molded by extrusion molding, and examples thereof include pellets, films, sheets, plates, rods, blocks, cylinders, containers, electric wires, tubes, bottles, and the like. The molded article is preferably a tube, a film or a bottle, and more preferably a tube. As described above, it is presumed that the low-molecular weight material is likely to adhere to the inner surface of the pipe and become a generation source of particles by the conventional molding method, but the production method of the present invention can obtain a pipe with a reduced generation amount of particles even in the case of producing a pipe.
An extruder may be used for the extrusion molding in the molding step. The extruder may be a single screw extruder or a twin screw extruder. The extruder generally includes: the apparatus includes a barrel, a screw housed in the barrel, a die attached to a front end of the barrel, a die adapter for connecting the die to the barrel, a hopper for supplying a raw material to the barrel, and a driving device for rotating the barrel. For the reason of easy charging from the hopper, pellets are preferred as the molding material prepared in the above-mentioned preparation step, as described above. The molding material charged into the cylinder is melted in the cylinder, extruded from the die, and molded into a tube. The temperature of the cylinder, die adapter, die, etc. may be set according to the size and shape of the molded article, and is preferably set so that the die temperature is the highest. As described above, it is presumed that in the tube molding step, the low molecular weight material volatilizes from the molten TFE/PAVE copolymer extruded from the die and easily adheres to the inner surface of the tube, and therefore, it is preferable to control the die temperature to T2.
As a particularly preferable embodiment of the production method of the present invention, there is a method comprising the steps of: a production step of preparing pellets by extrusion molding a TFE/PAVE copolymer using an extruder equipped with a die set at a temperature T1 or a cylinder set at a temperature T1 and an extruder equipped with a vent hole provided in the cylinder; and a molding step of obtaining a tube by extrusion molding the pellets by using an extruder equipped with a die set at a temperature T2 (DEG C); the temperature T1 and the temperature T2 satisfy the above relationship.
Next, the tetrafluoroethylene/perfluoro (alkyl vinyl ether) copolymer used in the above-mentioned production step will be described.
The TFE/PAVE copolymer is preferably a melt-processable fluororesin. In the present invention, melt processability means that a polymer can be processed by melting it using an existing processing apparatus such as an extruder or an injection molding machine. Therefore, the melt flow rate of the melt-processable fluororesin, as measured by the measurement method described later, is usually 0.01 to 500g/10 min.
The content of the PAVE-based monomer unit in the TFE/PAVE copolymer is preferably 1.0 to 10 mass%, more preferably 2.0 mass% or more, further preferably 3.5 mass% or more, particularly preferably 4.0 mass% or more, most preferably 5.0 mass% or more, more preferably 8.0 mass% or less, further preferably 7.0 mass% or less, particularly preferably 6.5 mass% or less, most preferably 6.0 mass% or less, relative to the total monomer units. The amount of the above PAVE-based monomer unit is determined by19F-NMR method.
As PAVE constituting the above-mentioned PAVE unit, at least one selected from the group consisting of a monomer represented by the general formula (1) and a monomer represented by the general formula (2):
general formula (1):
CF2＝CFO(CF2CFY1O)p-(CF2CF2CF2O)q-Rf(1)
(in the formula, Y1Represents F or CF3，RfRepresents a perfluoroalkyl group having 1 to 5 carbon atoms. p represents an integer of 0 to 5, q represents an integer of 0 to 5)
General formula (2):
CFX＝CXOCF2OR1(2)
(wherein X's are the same or different and represent H, F or CF)3，R1Represents a straight-chain or branched fluoroalkyl group having 1 to 6 carbon atoms which may contain 1 to 2 at least one atom selected from the group consisting of H, Cl, Br and I, or a cyclic fluoroalkyl group having 5 or 6 carbon atoms which may contain 1 to 2 at least one atom selected from the group consisting of H, Cl, Br and I).
Among these, the PAVE is preferably a monomer represented by the general formula (1), more preferably at least one selected from the group consisting of perfluoro (methyl vinyl ether), perfluoro (ethyl vinyl ether) and perfluoro (propyl vinyl ether) (PPVE), and still more preferably PPVE.
The TFE/PAVE copolymer is not particularly limited, but is preferably a copolymer in which the molar ratio of TFE units to PAVE units (TFE units/PAVE units) is 70/30 or more and less than 99/1. The molar ratio is more preferably from 70/30 to 98.9/1.1, and still more preferably from 80/20 to 98.9/1.1. When the amount of the TFE unit is too small, mechanical properties tend to be deteriorated, and when the amount of the TFE unit is too large, the melting point tends to be excessively increased, and moldability tends to be deteriorated.
The TFE/PAVE copolymer is preferably a copolymer having 0.1 to 10 mol% of a monomer unit derived from a monomer copolymerizable with TFE and PAVE and 90 to 99.9 mol% of a total of TFE unit and PAVE unit.
Examples of the monomer copolymerizable with TFE and PAVE include HFP and CZ3Z4＝CZ5(CF2)nZ6(in the formula, Z3、Z4And Z5Identical or different, represents H or F, Z6H, F or Cl, n is an integer of 2 to 10), and CF2＝CF-OCH2-Rf7(wherein Rf7A perfluoroalkyl group having 1 to 5 carbon atoms), and the like. Among them, HFP is preferable.
The TFE/PAVE copolymer is preferably at least one selected from the group consisting of a copolymer composed of only TFE units and PAVE units and the TFE/HFP/PAVE copolymer, and more preferably a copolymer composed of only TFE units and PAVE units.
The TFE/PAVE copolymer has a melting point of preferably 280 to 322 ℃, more preferably 290 ℃ or higher, further preferably 295 ℃ or higher, particularly preferably 300 ℃ or higher, and further preferably 315 ℃ or lower. In order to mold a copolymer having a high melting point, it is necessary to heat the copolymer to a high temperature to mold the copolymer, and therefore, the low molecular weight material is particularly likely to adhere to the surface of a molded article, and particles are likely to be generated. This is because the higher the molding temperature is, the more easily the low molecular weight material volatilizes from the copolymer during molding. According to the production method of the present invention, a molded article having a reduced amount of particles generated can be produced even when a TFE/PAVE copolymer having a high melting point is used. The melting point can be measured by using a differential scanning calorimeter [ DSC ].
The TFE/PAVE copolymer preferably has a glass transition temperature (Tg) of 70 to 110 ℃, more preferably 80 ℃ or higher, and still more preferably 100 ℃ or lower. The glass transition temperature can be measured by dynamic viscoelasticity measurement.
The TFE/PAVE copolymer has a Melt Flow Rate (MFR) at 372 ℃ of preferably 0.1 to 100g/10 min, more preferably 0.5g/10 min or more, further preferably 1g/10 min or more, still more preferably 80g/10 min or less, further preferably 40g/10 min or less, and particularly preferably 30g/10 min or less. The MFR is a value obtained as follows: the MFR was determined as the mass (g/10 min) of the polymer discharged from a nozzle having an inner diameter of 2mm and a length of 8mm at 372 ℃ under a load of 5kg per 10 min using a melt flow index meter (manufactured by Anthemis Seisakusho Co., Ltd.) according to ASTM D1238.
The TFE/PAVE copolymer is preferably a copolymer having a small number of functional groups, preferably 10 times, for the reason that a molded article having a further reduced amount of particles can be produced6The carbon atoms have 0 to 50 functional groups in total. Every 10 th6The number of functional groups having carbon atoms is more preferably 0 to 30, and still more preferably 0 to 15.
The functional group is a functional group present at the end of the main chain or the end of a side chain of the TFE/PAVE copolymer and a functional group present in the main chain or the side chain. The functional group is preferably selected from the group consisting of-CF ═ CF2、-CF2H、-COF、-COOH、-COOCH3、-CONH2and-CH2At least one of the group consisting of OH.
For the identification of the kind of the functional group and the measurement of the number of functional groups, infrared spectroscopic analysis can be used.
The number of functional groups is specifically measured by the following method. Firstly, the TFE/PAVE copolymer is melted for 30 minutes at 330-340 ℃, and thenAnd performing compression molding to prepare a film with the thickness of 0.25-0.3 mm. The film was analyzed by Fourier transform infrared spectroscopy to obtain the infrared absorption spectrum of the above TFE/PAVE copolymer, and a differential spectrum with a background spectrum which was completely fluorinated without the presence of functional groups was obtained. From the absorption peaks of the specific functional groups appearing in the differential spectrum, each 1X 10 of the TFE/PAVE copolymer was calculated from the following formula (A)6Number of functional groups N of carbon atoms.
N＝I×K/t(A)
I: absorbance of the solution
K: correction factor
t: thickness of film (mm)
The absorption frequency, molar absorption coefficient and calibration coefficient of the functional groups in the present invention are shown in table 1 for reference. In addition, the molar absorption coefficient was determined from FT-IR measurement data of a low molecular model compound.
[ Table 1]
Note that-CH2CF2H、-CH2COF、-CH2COOH、-CH2COOCH3、-CH2CONH2Respectively, to the absorption frequencies shown in the table2H. -COF, -COOH free and-COOH bound, -COOCH3、-CONH2Has an absorption frequency lower than that of (1) a few tens of Kessel (cm)-1)。
Thus, for example, the number of functional groups of the-COF is due to the assignment to the-CF2Absorption frequency of COF 1883cm-1The sum of the numbers of functional groups determined from the absorption peaks of (A) and (B) is ascribed to-CH2Absorption frequency of COF 1840cm-1The total number of functional groups obtained from the absorption peak of (1).
The number of the functional groups may be-CF ═ CF2、-CF2H、-COF、-COOH、-COOCH3、-CONH2and-CH2The total number of OH groups.
The functional group may be derived from, for example, a chain transfer agent or a polymer used in the production of the TFE/PAVE copolymerThe polymerization initiator is introduced into the TFE/PAVE copolymer described above. For example, an alcohol is used as the chain transfer agent, and a compound having-CH is used as the polymerization initiator2In the case of peroxides having an OH structure, it is possible to introduce-CH into the main chain end of the TFE/PAVE copolymer2And (5) OH. Further, the functional group can be introduced into the end of the side chain of the TFE/PAVE copolymer by polymerizing a monomer having the functional group.
The TFE/PAVE copolymer having such a functional group is fluorinated to obtain the TFE/PAVE copolymer having a functional group number within the above range. That is, the TFE/PAVE copolymer used in the production method of the present invention is preferably subjected to fluorination treatment. Further, the TFE/PAVE copolymer used in the production process of the present invention preferably has-CF3A terminal group.
The fluorination treatment can be carried out by contacting a TFE/PAVE copolymer which has not been subjected to fluorination treatment with a fluorine-containing compound.
The fluorine-containing compound is not particularly limited, and examples thereof include a fluorine radical source which generates fluorine radicals under fluorination treatment conditions. The fluorine radical source may be F2Gas, CoF3、AgF2、UF6、OF2、N2F2、CF3OF, fluorinated halides (e.g. IF)5、ClF3) And the like.
Above F2The fluorine radical source such as a gas may be a substance having a concentration of 100%, but from the viewpoint of safety, it is preferably used by mixing with an inert gas and diluting to 5 to 50% by mass, more preferably 15 to 30% by mass. The inert gas includes nitrogen, helium, argon, and the like, and nitrogen is preferable from the viewpoint of economy.
The fluorination treatment is carried out under conditions not particularly limited, and the molten TFE/PAVE copolymer may be brought into contact with the fluorine-containing compound, and the fluorination treatment may be carried out at a temperature usually not higher than the melting point of the TFE/PAVE copolymer, preferably 20 to 220 ℃, more preferably 100 to 200 ℃. The fluorination treatment is usually carried out for 1 to 30 hours, preferably for 5 to 25 hours. The fluorination treatment is preferably carried out without using fluorineTFE/PAVE copolymer treated with fluorine gas (F)2Gas) contact.
The TFE/PAVE copolymer can be produced by a conventionally known method such as emulsion polymerization or suspension polymerization by appropriately mixing monomers constituting the structural unit thereof and additives such as a polymerization initiator.
Next, the molded article of the present invention will be described. The molded article of the present invention contains a TFE/PAVE copolymer having a melting point of 295 ℃ or higher, and when the molded article is brought into contact with isopropanol, the number of particles having a diameter of 30nm or more dispersed in the isopropanol is 700/ml or less.
The TFE/PAVE copolymer contained in the molded article of the present invention is the same as the TFE/PAVE copolymer used in the production method of the present invention, and preferably the same as the TFE/PAVE copolymer used in the production method of the present invention.
The TFE/PAVE copolymer contained in the molded article of the present invention has a melting point of 295 ℃ or higher. In order to mold a copolymer having a high melting point, it is necessary to heat the copolymer to a high temperature for molding, and therefore, the low molecular weight material is particularly likely to adhere to the surface of a molded article, and particles are likely to be generated. The molded article of the present invention contains a TFE/PAVE copolymer having a melting point of 295 ℃ or higher, but the amount of particles generated is small. The melting point of the TFE/PAVE copolymer is more preferably 300 ℃ or higher, preferably 322 ℃ or lower, and more preferably 315 ℃ or lower.
When the molded article of the present invention is brought into contact with isopropyl alcohol (the number of particles having a diameter of 30nm or more is 30/ml or less), the number of particles dispersed in isopropyl alcohol is 700/ml or less, preferably 600/ml or less, more preferably 500/ml or less, and the lower limit is not particularly limited, and is preferably 50/ml or more. The method for determining the number of particles dispersed in isopropanol is described below.
The shape of the molded article of the present invention is not particularly limited, and examples thereof include pellets, films, sheets, plates, rods, blocks, cylinders, containers, wires, tubes, bottles, and the like. The molded article of the present invention is preferably a tube, a film or a bottle, and more preferably a tube. As described above, it is presumed that the low molecular weight material is likely to adhere to the inner surface of the tube and become a generation source of particles by the conventional molding method, but the molded product of the present invention has a small generation amount of particles even in the case of the tube.
In the case where the tube is filled with an amount of isopropyl alcohol equivalent to the amount of the tube's internal volume (the number of particles having a diameter of 30nm or more is 30/ml or less), and the isopropyl alcohol is recovered after leaving at room temperature for one day, the number of particles having a diameter of 30nm or more dispersed in the recovered isopropyl alcohol is preferably 700/ml or less, more preferably 600/ml or less, and still more preferably 500/ml or less, and the lower limit is not particularly limited, and preferably 50/ml or more. The method for determining the number of particles dispersed in isopropanol is described below.
The outer diameter of the pipe is not particularly limited, and may be 2 to 100mm, or 5 to 50 mm. The thickness of the tube may be 0.1 to 10mm, or 0.3 to 5 mm. According to the production method of the present invention, the number of particles dispersed in isopropyl alcohol can be controlled within the above range, particularly, even when a relatively large pipe having an outer diameter of 20mm or more and a thickness of 1mm or more is produced. Therefore, the pipe of the present invention may have an outer diameter of 20mm or more and a thickness of 1mm or more.
The molded article of the present invention and the molded article obtained by the production method of the present invention are not particularly limited, and can be used in the following applications, for example:
diaphragm parts of diaphragm pumps, bellows molded articles, wire-coated articles, parts for semiconductors, gaskets and seals, thin-walled tubes for copying rollers, monofilaments, tapes, gaskets, optical lens parts, pipes for oil excavation, pipes for geothermal power generation, wires for oil excavation, wires for satellites, wires for nuclear power generation, wires for aircrafts, solar cell panel films, gaskets for secondary batteries, electric double layer capacitors, and the like, OA rollers, and the like.
The molded article can be suitably used as a tube for flowing a gas or a reagent, a bottle for storing a chemical, a gas bag, a reagent container, a bag for cryopreservation, and the like.
The molded article can be suitably used for valve bodies and parts for opening and closing valves, sleeves used for connecting a joint and a tube, screw caps for reagent bottles and containers, gears, screws, frying pans, rice cookers, products in which a metal or other base is coated with a fluororesin, release films, and the like.
Particularly suitable applications of the molded article are a piping of a reagent supply facility for semiconductor production, a pipe for a semiconductor production apparatus, a joint, a valve, a tank, a container, a reagent bag, a wafer carrier, and other perfluoro-fluororesin members.
The molded article of the present invention and the molded article obtained by the production method of the present invention are also one of suitable embodiments.
In semiconductor factories, pipes for passing ultrapure water or high-purity reagents used in semiconductor production are often used. The fine particles (granules) produced from the molded article comprising the TFE/PAVE copolymer have hydrophobicity. Therefore, in particular, in the case where an aqueous reagent flows through the tube, the particles are likely to adhere to the inner surface of the tube due to the interaction between the particles and the tube, and the adhered particles are difficult to remove with washing water such as pure water. Therefore, when a new pipe is used in a semiconductor factory, there are problems that a large amount of ultrapure water or a reagent is required for cleaning (rinsing) the pipe, or a long time is required for cleaning.
Since the tube has the above-described structure, particles hardly adhere to the inner surface, and particles are less likely to be generated. The tube is preferably a tube for reagent piping for flowing a reagent because the tube exerts such an effect. Examples of the reagent include reagents used in semiconductor production, for example, ammonia water, ozone water, hydrogen peroxide, hydrochloric acid, sulfuric acid, a resist solution, a diluent, a developer, and the like.
While the embodiments have been described above, it should be understood that various changes in form and details may be made therein without departing from the spirit and scope of the claims.
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