CN116917349A

CN116917349A - Injection molded article and method for producing same

Info

Publication number: CN116917349A
Application number: CN202280016582.5A
Authority: CN
Inventors: 滨田博之; 津田早登; 井坂忠晴; 山本有香里; 善家佑美
Original assignee: Daikin Industries Ltd
Current assignee: Daikin Industries Ltd
Priority date: 2021-02-26
Filing date: 2022-01-31
Publication date: 2023-10-20

Abstract

The present invention provides an injection-molded article comprising a copolymer comprising tetrafluoroethylene units and fluoro (alkyl vinyl ether) units, wherein the content of fluoro (alkyl vinyl ether) units of the copolymer is 4.7 to 7.0 mass% relative to the total monomer units, the melt flow rate of the copolymer at 372 ℃ is 11.0 to 22.0g/10 min, the melting point of the copolymer is 296 to 305 ℃, and the release amount of fluoride ions from the injection-molded article to water is 7500 [ mu ] g/m ² The following is given.

Description

Injection molded article and method for producing same

Technical Field

The present invention relates to an injection molded article and a method for producing the same.

Background

Patent document 1 describes an ozone-resistant injection-molded article comprising a perfluoro resin, wherein the perfluoro resin comprises a perfluoropolymer having an MIT value of 30 ten thousand times or more and each 1×10 of the perfluoropolymer ⁶ The number of unstable terminal groups in the number of carbon atoms is 50 or less.

Prior art literature

Patent literature

Patent document 1: international publication No. 2003/048214

Disclosure of Invention

Problems to be solved by the invention

The purpose of the present invention is to provide an injection-molded article which has excellent physical properties such as low water vapor permeability, low reagent permeability, abrasion resistance, mechanical properties, rigidity at high temperatures, etc., and which has greatly improved ozone resistance.

Means for solving the problems

According to the present invention, there is provided an injection-molded article comprising a copolymer comprising tetrafluoroethylene units and fluoro (alkyl vinyl ether) units, wherein the content of fluoro (alkyl vinyl ether) units of the copolymer is 4.7 to 7.0 mass% relative to the total monomer units, the melt flow rate of the copolymer at 372 ℃ is 11.0 to 10 minutes to 22.0g/10 minutes, the melting point of the copolymer is 296 to 305 ℃, and the release amount of fluoride ions from the injection-molded article to water is 7500 [ mu ] g/m ² The following is given.

In the injection-molded article of the present invention, the amount of elution of fluorine ions from the injection-molded article to water is preferably 5500μg/m ² The following is given.

In the injection-molded article of the present invention, the metal elution amount from the injection-molded article to 50 mass% hydrofluoric acid is preferably 200. Mu.g/m ² The following is given.

In the injection-molded article of the present invention, the fluoro (alkyl vinyl ether) unit of the copolymer is preferably a perfluoro (propyl vinyl ether) unit.

In the injection-molded article of the present invention, the content of the fluoro (alkyl vinyl ether) unit of the copolymer is preferably 4.9 to 6.9 mass% with respect to the total monomer units.

In the injection-molded article of the present invention, the melt flow rate of the copolymer at 372℃is preferably 13.0g/10 min to 20.0g/10 min.

In the injection-molded article of the present invention, every 10 of the copolymer ⁶ The number of functional groups having the number of main chain carbon atoms is 20 or less.

The injection-molded body of the present invention is preferably a nut.

Further, according to the present invention, there is provided a method for producing the injection-molded article, wherein the injection-molded article is obtained by injection molding the copolymer using an injection molding machine having a barrel and a screw accommodated in the barrel.

In the production method of the present invention, the temperature of the copolymer in the cylinder is preferably adjusted to 385 to 395 ℃.

In the production method of the present invention, it is preferable that a cylinder subjected to Ni plating or a cylinder formed of a Ni-based alloy is used as the cylinder; as the screw, a screw formed of a Ni-based alloy and provided with a plasticizing head at the tip is used.

Effects of the invention

According to the present invention, there is provided an injection-molded article which is excellent in physical properties such as low water vapor permeability, low reagent permeability, abrasion resistance, mechanical properties, rigidity at high temperature, etc., and has significantly improved ozone resistance.

Drawings

Fig. 1 is a top view, a front view and a bottom view for explaining the shape of nuts produced in experimental examples and comparative examples.

Detailed Description

Hereinafter, specific embodiments of the present invention will be described in detail, but the present invention is not limited to the following embodiments.

Patent document 1 proposes an ozone resistant injection molded article comprising a perfluoro resin having an MIT value of 30 ten thousand times or more, wherein each 1×10 of the perfluoro resin is a perfluoro polymer, particularly as an article excellent in ozone resistance such as piping material and joint used in a semiconductor manufacturing apparatus ⁶ The number of unstable terminal groups in the number of carbon atoms is 50 or less.

Furthermore, example 4 of patent document 1 describes: using tetrafluoroethylene/perfluoro (propyl vinyl ether) copolymer having a Melt Flow Rate (MFR) of 14.8g/10 min, cap nuts were produced by injection molding, and the cap nuts were subjected to ozone exposure test, as a result, more than 10 cracks were generated after 90 days. Such a cap nut also has sufficient ozone resistance, but if an injection-molded body with further improved ozone resistance can be obtained, the cost can be reduced as a result of the longer life of the component.

As a result of intensive studies on means for solving the problems, the inventors of the present invention have found that an injection-molded article produced using a copolymer having a relatively high MFR of about 14.8g/10 min tends to have a lower ozone resistance than an injection-molded article produced using a copolymer having a relatively low MFR. Further, as a result of further studies on injection conditions in addition to the constitution of the copolymer used in injection molding, it was found that even when a copolymer having a relatively high MFR of about 14.8g/10 min was used, the ozone resistance of the injection-molded article was significantly improved when the amount of fluorine ion elution from the injection-molded article to water was small, and the injection-molded article of the present invention was completed.

That is, the injection-molded article of the present invention is an injection-molded article comprising a specific copolymer, wherein the amount of fluorine ions released from the injection-molded article into water is 7500. Mu.g/m ² The following is given. Since the injection-molded article of the present invention has such a constitution, it is excellent in physical properties such as low water vapor permeability, low reagent permeability, abrasion resistance, mechanical properties, rigidity at high temperature, and ozone resistance. Therefore, for example, when the injection-molded article of the present invention is used as a nut, a nut having a thread which is not easily cut, is not easily broken even when used in an environment in contact with ozone gas or ozone water, is not easily deformed even when used at a high temperature, and is not easily loosened can be obtained. Further, such nuts are also high in tensile strength and are not easily broken.

The amount of fluoride ion released from the injection-molded article into water was 7500. Mu.g/m ² Hereinafter, from the viewpoint of further improving ozone resistance of the injection-molded article, it is preferably 5500. Mu.g/m ² The ratio is preferably 5000. Mu.g/m ² Hereinafter, 4500. Mu.g/m is particularly preferable ² The following is given. The lower limit of the amount of elution of fluorine ions is not particularly limited, but is preferably low, and may be, for example, 100. Mu.g/m ² The above may be 500. Mu.g/m ² The above.

The amount of fluoride ion released from the injection-molded article into water can be determined as follows: after immersing the injection-molded article in water at 121 ℃ for 1 hour, the fluoride ion concentration of the recovered water was measured by using a fluoride ion meter, and the fluoride ion elution amount per unit surface area of the injection-molded article was calculated, thereby determining.

Further, as a result of intensive studies, the present inventors have found that an injection-molded article exhibits further improved ozone resistance when the amount of fluoride ions eluted from the injection-molded article is small and the amount of metal eluted from the injection-molded article to 50 mass% hydrofluoric acid is small.

In view of further improving the ozone resistance of the injection-molded article, the metal elution amount from the injection-molded article to 50 mass% hydrofluoric acid is preferably 200. Mu.g/m ² Hereinafter, 150. Mu.g/m is more preferable ² The following is more preferable to be 100. Mu.g/m ² The following is particularly preferred to be 50. Mu.g/m ² The following is given. The lower limit of the amount of metal eluted is not particularly limited, but is preferably low, and may be, for example, 0.1. Mu.g/m ² The above may be 0.5. Mu.g/m ² The above may be 1.0. Mu.g/m ² The above may be 5. Mu.g/m ² The above.

In the present invention, the metal elution amount means the total elution amount of iron, chromium and nickel eluted from the injection-molded body to 50 mass% hydrofluoric acid. The metal elution amount from the injection-molded article to 50 mass% hydrofluoric acid can be determined as follows: after immersing the injection-molded article in 50 mass% hydrofluoric acid at 25 ℃ for 24 hours, the metal concentration in a measurement solution prepared from the recovered 50 mass% hydrofluoric acid was measured using an ICP emission analyzer, and the amount of metal eluted per unit surface area of the injection-molded article was calculated to determine.

The injection-molded article having the fluoride ion elution amount and the metal elution amount within the above ranges can be produced by a method for producing an injection-molded article described later using a specific copolymer.

The injection molded article of the present invention contains a copolymer containing Tetrafluoroethylene (TFE) units and fluoro (alkyl vinyl ether) (FAVE) units. The copolymer is a melt-processible fluororesin. Melt processability means that a polymer can be melted and processed using existing processing equipment such as an extruder and an injection molding machine.

As the FAVE constituting the above-mentioned FAVE 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) is exemplified.

General formula (1):

CF ₂ ＝CFO(CF ₂ CFY ¹ O) _p -(CF ₂ CF ₂ CF ₂ O) _q -Rf (1)

(wherein Y is ¹ Represents F or CF ₃ Rf represents a perfluoroalkyl group having 1 to 5 carbon atoms, p represents an integer of 0 to 5, and q represents an integer of 0 to 5. )

General formula (2):

CFX＝CXOCF ₂ OR ¹ (2)

(wherein X is the same or different and represents H, F or CF ₃ ，R ¹ Represents a straight chain or branched chain and may contain 1 to 2 carbon atoms of 1 to 2 atoms selected from the group consisting of H, cl, br and I-6 fluoroalkyl; or represents a cyclic fluoroalkyl group having 5 or 6 carbon atoms which may contain 1 to 2 atoms of at least 1 selected from the group consisting of H, cl, br and I. )

Among them, as the above FAVE, monomers represented by the general formula (1) are preferable, at least 1 selected from the group consisting of perfluoro (methyl vinyl ether), perfluoro (ethyl vinyl ether) (PEVE) and perfluoro (propyl vinyl ether) (PPVE) are more preferable, at least 1 selected from the group consisting of PEVE and PPVE are more preferable, and PPVE is particularly preferable.

The FAVE unit content of the copolymer is 4.7 to 7.0 mass% relative to the total monomer units. The content of the FAVE unit in the copolymer is preferably 4.8% by mass or more, more preferably 4.9% by mass or more, still more preferably 5.0% by mass or more, particularly preferably 5.1% by mass or more, most preferably 5.2% by mass or more, preferably 6.9% by mass or less, more preferably 6.8% by mass or less, still more preferably 6.7% by mass or less, particularly preferably 6.6% by mass or less, and most preferably 6.2% by mass or less. By setting the FAVE unit content of the copolymer within the above range, the injection-molded article is excellent in physical properties such as low water vapor permeability, abrasion resistance, mechanical properties, and rigidity at high temperatures. When the content of FAVE units in the copolymer is too small, ozone resistance, abrasion resistance and mechanical properties of the injection-molded article deteriorate. If the FAVE unit content of the copolymer is too large, the injection-molded article will have low water vapor permeability and poor rigidity at high temperatures.

The TFE unit content of the copolymer is preferably 93.0 to 95.3 mass%, more preferably 93.1 mass% or more, still more preferably 93.2 mass% or more, still more preferably 93.3 mass% or less, particularly preferably 93.4 mass% or more, most preferably 93.8 mass% or more, still more preferably 95.2 mass% or less, still more preferably 95.1 mass% or less, still more preferably 95.0 mass% or less, particularly preferably 94.9 mass% or less, and most preferably 94.8 mass% or less, based on the total monomer units. By setting the TFE unit content of the copolymer within the above range, the injection molded article is excellent in physical properties such as low water vapor permeability, abrasion resistance, mechanical properties, and rigidity at high temperature. When the content of TFE unit of the copolymer is too large, ozone resistance, abrasion resistance and mechanical properties of the injection molded body are deteriorated. When the content of TFE unit in the copolymer is too small, the injection-molded article may have low water vapor permeability and poor rigidity at high temperature.

In the present invention, the content of each monomer unit in the copolymer is determined by ¹⁹ F-NMR measurement.

The copolymer may also contain monomer units derived from monomers copolymerizable with TFE and FAVE. In this case, the content of the monomer unit copolymerizable with TFE and FAVE is preferably 0 to 2.3% by mass, more preferably 0.05 to 1.5% by mass, and even more preferably 0.1 to 0.5% by mass, based on the total monomer units of the copolymer.

Examples of monomers copolymerizable with TFE and FAVE include Hexafluoropropylene (HFP) and CZ ¹ Z ² ＝CZ ³ (CF ₂ ) _n Z ⁴ (wherein Z is ¹ 、Z ² And Z ³ Identical or different, H or F, Z ⁴ H, F or Cl, n represents an integer of 2 to 10), and CF ₂ ＝CF-OCH ₂ -Rf ¹ (wherein Rf ¹ A perfluoroalkyl group having 1 to 5 carbon atoms. ) Alkyl perfluorovinyl ether derivatives shown and the like. Among them, HFP is preferable.

The copolymer is preferably at least one selected from the group consisting of a copolymer composed of only TFE units and FAVE units and a TFE/HFP/FAVE copolymer, and more preferably a copolymer composed of only TFE units and FAVE units.

The Melt Flow Rate (MFR) of the copolymer is 11.0 to 22.0g/10 min. The MFR of the copolymer is preferably 12.0g/10 min or more, more preferably 13.0g/10 min or more, preferably 21.0g/10 min or less, more preferably 20.0g/10 min or less, further preferably 18.0g/10 min or less, particularly preferably 17.0g/10 min or less. Since the injection-molded article of the present invention contains a copolymer having a high MFR, it can be easily produced by injection molding, and even if such a copolymer having a high MFR is contained, ozone resistance is excellent. If the MFR of the copolymer is too high, ozone resistance, abrasion resistance and mechanical properties of the injection-molded article deteriorate. If the MFR of the copolymer is too low, the molding of the copolymer becomes difficult, and for example, there is a problem that it is difficult to mold a nut having a thread having a desired shape. If the MFR of the copolymer is too low, the injection-molded article will have low water vapor permeability, low reagent permeability, and poor rigidity at high temperatures.

In the present invention, MFR is a value obtained as a mass (g/10 min) of a polymer flowing out from a nozzle having an inner diameter of 2.1mm and a length of 8mm at 372℃under a 5kg load every 10 minutes using a melt index meter according to ASTM D1238.

The MFR can be adjusted by adjusting the kind and amount of a polymerization initiator used in polymerizing the monomers, the kind and amount of a chain transfer agent, and the like.

In the present invention, every 10 of the copolymer ⁶ The number of functional groups having carbon atoms in the main chain is preferably 20 or less, more preferably 15 or less, and still more preferably less than 6. By setting the number of functional groups of the copolymer within the above range, the amount of fluoride ions released from the injection-molded article to water can be reduced more easily, and as a result, ozone resistance of the injection-molded article can be improved more easily. Further, by setting the number of functional groups of the copolymer within the above range, the injection-molded article is also improved in low permeability to a reagent such as methyl ethyl ketone.

The identification of the kind of the functional group and the measurement of the number of functional groups may be performed by infrared spectroscopic analysis.

Specifically, the number of functional groups was measured by the following method. First, the copolymer was cold-molded to prepare a film having a thickness of 0.25mm to 0.3 mm. The film was analyzed by fourier transform infrared spectroscopy to obtain the infrared absorption spectrum of the above copolymer, and to obtain a differential spectrum from the fully fluorinated background spectrum without functional groups. The specific absorption peak of the specific functional group in the copolymer was calculated for every 1X 10 based on the following formula (A) ⁶ Number of functional groups N of carbon atoms.

N＝I×K/t (A)

I: absorbance of light

K: correction coefficient

t: film thickness (mm)

For reference, the absorption frequency, molar absorptivity, and correction factor are shown in table 1 for some functional groups. The molar absorptivity was determined from FT-IR measurement data of the low molecular weight model compound.

TABLE 1

-CH ₂ CF ₂ H、-CH ₂ COF、-CH ₂ COOH、-CH ₂ COOCH ₃ 、-CH ₂ CONH ₂ The absorption frequency ratios of (C) are shown in the tables respectively for-CF ₂ H. -COF, free-COOH and bonded-COOH, -COOCH ₃ 、-CONH ₂ Is tens of kesse (cm) ^-1 )。

For example, the functional group number of-COF means the number of functional groups derived from-CF ₂ Absorption frequency of COF 1883cm ^-1 The number of functional groups obtained from the absorption peak at the site and the number of functional groups obtained from the absorption peak derived from-CH ₂ Absorption frequency of COF 1840cm ^-1 The total number of functional groups obtained from the absorption peak at the position.

The functional groups are functional groups present at the main chain end or side chain end of the copolymer and functional groups present in the main chain or side chain. The number of functional groups may be-cf=cf ₂ 、-CF ₂ H、-COF、-COOH、-COOCH ₃ 、-CONH ₂ and-CH ₂ Total number of OH.

The functional group is introduced into the copolymer, for example, by a chain transfer agent or a polymerization initiator used in producing the copolymer. For example, using alcohols as chain transfer agents, or using compounds having-CH ₂ In the case of peroxides of OH structure as polymerization initiators, -CH ₂ OH is introduced into the backbone end of the copolymer. In addition, the functional group is introduced into the terminal of the side chain of the copolymer by polymerizing a monomer having the functional group.

By having pairs ofThe copolymer having such functional groups is fluorinated to obtain a copolymer having the number of functional groups in the above range. That is, the copolymer contained in the injection-molded article of the present invention is preferably a copolymer after the fluorination treatment. The copolymer contained in the injection-molded article of the present invention preferably also has-CF ₃ End groups.

The melting point of the copolymer is preferably 296 to 305℃and more preferably 299℃or higher. When the melting point is within the above range, the injection-molded article is further excellent in physical properties such as low water vapor permeability, low reagent permeability, abrasion resistance, mechanical properties, and rigidity at high temperature, and ozone resistance is further improved.

The injection-molded article of the present invention may contain other components such as fillers, plasticizers, processing aids, mold release agents, pigments, flame retardants, lubricants, light stabilizers, weather stabilizers, conductive agents, antistatic agents, ultraviolet absorbers, antioxidants, foaming agents, fragrances, oils, softeners, dehydrofluorination agents, and the like.

Examples of the filler include silica, kaolin, clay, organized clay, talc, mica, alumina, calcium carbonate, calcium terephthalate, titanium oxide, calcium phosphate, calcium fluoride, lithium fluoride, crosslinked polystyrene, potassium titanate, carbon, boron nitride, carbon nanotubes, and glass fibers. Examples of the conductive agent include carbon black. Examples of the plasticizer include dioctyl phthalate and pentaerythritol. Examples of the processing aid include carnauba wax, sulfone compound, low molecular weight polyethylene, and fluorine-based aid. Examples of the dehydrofluorination agent include organic onium and amidines.

As the other components, other polymers than the above copolymers may be used. Examples of the other polymer include a fluororesin other than the above copolymer, a fluororubber, a nonfluorinated polymer, and the like.

The copolymer contained in the injection-molded article of the present invention can be produced by a polymerization method such as suspension polymerization, solution polymerization, emulsion polymerization, or bulk polymerization. As the polymerization method, emulsion polymerization or suspension polymerization is preferable. In these polymerizations, the conditions such as temperature and pressure, polymerization initiator, and other additives may be appropriately set according to the composition and amount of the copolymer.

As the polymerization initiator, an oil-soluble radical polymerization initiator or a water-soluble radical polymerization initiator can be used.

The oil-soluble radical polymerization initiator may be a known oil-soluble peroxide, and the following are exemplified as typical examples:

dialkyl peroxycarbonates such as di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, and di-2-ethoxyethyl peroxydicarbonate;

peroxyesters such as t-butyl peroxyisobutyrate and t-butyl peroxypivalate;

Dialkyl peroxides such as di-t-butyl peroxide;

di [ fluoro (or fluoro chloro) acyl ] peroxides; etc.

As bis [ fluoro (or fluoro chloro) acyl groups]The peroxides include [ (RfCOO) & lt- & gt ]] ₂ (Rf is perfluoroalkyl, omega-hydroperfluoroalkyl or fluorochloroalkyl).

Examples of the di [ fluoro (or fluorochloroacyl ] peroxides include di (ω -hydro-dodecafluoroheptanoyl) peroxide, di (ω -hydro-hexadecanoyl) peroxide, di (perfluoropropionyl) peroxide, di (perfluorobutanoyl) peroxide, di (perfluoropentanoyl) peroxide, di (perfluorohexanoyl) peroxide, di (perfluoroheptanoyl) peroxide, di (perfluorooctanoyl) peroxide, di (perfluorononanoyl) peroxide, di (ω -chloro-hexafluorobutanoyl) peroxide, di (ω -chloro-dodecafluoroheptanoyl) peroxide, di (ω -chloro-dodecafluorooctanoyl) peroxide, ω -hydro-dodecafluoroheptanoyl-peroxide, ω -chloro-hexafluorobutanoyl-peroxide, ω -hydrododecafluoroheptanoyl-perfluorobutanoyl-peroxide, di (perfluoroheptanoyl) peroxide, di (dichloro-heptanoyl) peroxide, di (dichloro-dodecanoyl) peroxide, and di (dichloro-dodecanoyl) dodecanoyl peroxide.

The water-soluble radical polymerization initiator may be a known water-soluble peroxide, and examples thereof include ammonium salts such as persulfuric acid, perboric acid, perchloric acid, perphosphoric acid, and percarbonic acid, potassium salts, sodium salts, disuccinic acid peroxide, and organic peroxides such as dipentaerythritol peroxide, t-butyl peroxymaleate, and t-butyl hydroperoxide. The reducing agent such as sulfite may be used in combination with the peroxide in an amount of 0.1 to 20 times the amount of the peroxide.

In the polymerization, a surfactant, a chain transfer agent and a solvent may be used, and conventionally known ones may be used, respectively.

As the surfactant, a known surfactant can be used, and for example, a nonionic surfactant, an anionic surfactant, a cationic surfactant, and the like can be used. Among them, the fluorinated anionic surfactant is preferable, and the fluorinated anionic surfactant having 4 to 20 carbon atoms, which may be linear or branched, and which may or may not contain ether-bonded oxygen (i.e., may have an oxygen atom interposed between carbon atoms), is more preferable. The amount of the surfactant to be added (relative to the polymerization water) is preferably 50ppm to 5000ppm.

Examples of the chain transfer agent include: hydrocarbons such as ethane, isopentane, n-hexane, and cyclohexane; aromatic compounds such as toluene and xylene; ketones such as acetone; acetate esters such as ethyl acetate and butyl acetate; alcohols such as methanol and ethanol; mercaptans such as methyl mercaptan; halogenated hydrocarbons such as carbon tetrachloride, chloroform, methylene chloride and methyl chloride; etc. The amount of the chain transfer agent to be added may vary depending on the amount of the chain transfer constant of the compound to be used, and is usually in the range of 0.01 to 20% by mass relative to the polymerization solvent.

Examples of the solvent include water, a mixed solvent of water and alcohol, and the like.

In the suspension polymerization, a fluorine-based solvent may be used in addition to water. As the fluorine-based solvent, CH may be mentioned ₃ CClF ₂ 、CH ₃ CCl ₂ F、CF ₃ CF ₂ CCl ₂ H、CF ₂ ClCF ₂ Hydrochlorofluoroalkanes such as CFHCl; CF (compact flash) ₂ ClCFClCF ₂ CF ₃ 、CF ₃ CFClCFClCF ₃ Isophlorofluoroalkanes; CF (compact flash) ₃ CFHCFHCF ₂ CF ₂ CF ₃ 、CF ₂ HCF ₂ CF ₂ CF ₂ CF ₂ H、CF ₃ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ CF ₂ Hydrofluoroalkanes such as H; CH (CH) ₃ OC ₂ F ₅ 、CH ₃ OC ₃ F ₅ CF ₃ CF ₂ CH ₂ OCHF ₂ 、CF ₃ CHFCF ₂ OCH ₃ 、CHF ₂ CF ₂ OCH ₂ F、(CF ₃ ) ₂ CHCF ₂ OCH ₃ 、CF ₃ CF ₂ CH ₂ OCH ₂ CHF ₂ 、CF ₃ CHFCF ₂ OCH ₂ CF ₃ Isohydrofluoroethers; perfluorocyclobutane, CF ₃ CF ₂ CF ₂ CF ₃ 、CF ₃ CF ₂ CF ₂ CF ₂ CF ₃ 、CF ₃ CF ₂ CF ₂ CF ₂ CF ₂ CF ₃ Among them, perfluoroalkanes are preferable. The amount of the fluorine-based solvent to be used is preferably 10 to 100% by mass based on the aqueous medium in view of suspension property and economy.

The polymerization temperature is not particularly limited, and may be 0 to 100 ℃. The polymerization pressure is appropriately determined depending on the kind and amount of the solvent used, the vapor pressure, the polymerization temperature, and other polymerization conditions, and may be generally 0 to 9.8MPaG.

When an aqueous dispersion containing a copolymer is obtained by polymerization, the copolymer contained in the aqueous dispersion can be precipitated, washed, and dried to recover the copolymer. In addition, in the case where the copolymer is obtained as a slurry by polymerization, the copolymer can be recovered by taking out the slurry from the reaction vessel, washing it, and drying it. The copolymer can be recovered in the form of a powder by drying.

The copolymer obtained by polymerization may be molded into pellets. The molding method for molding the pellets is not particularly limited, and conventionally known methods can be used. For example, a method of melt-extruding a copolymer using a single screw extruder, a twin screw extruder, or a tandem extruder, cutting the copolymer into a predetermined length, and molding the copolymer into pellets, and the like can be mentioned. The extrusion temperature at the time of melt extrusion is required to be changed depending on the melt viscosity of the copolymer and the production method, and is preferably from +20℃to +140℃of the melting point of the copolymer. The method of cutting the copolymer is not particularly limited, and conventionally known methods such as a wire cutting method, a thermal cutting method, an underwater cutting method, and a sheet cutting method can be employed. The volatile components in the pellets may also be removed by heating the resulting pellets (degassing treatment). The obtained pellets may be treated by contacting them with warm water at 30 to 200 ℃, steam at 100 to 200 ℃ or hot air at 40 to 200 ℃.

The copolymer obtained by polymerization may also be subjected to a fluorination treatment. The fluorination treatment may be performed by contacting the copolymer that has not been subjected to the fluorination treatment with a fluorine-containing compound. By fluorination treatment, the-COOH, -COOCH-of the copolymer can be obtained ₃ 、-CH ₂ OH、-COF、-CF＝CF ₂ 、-CONH ₂ Isothermally labile functional groups and relatively thermally stable-CF ₂ Conversion of functional groups such as H to extremely thermally stable-CF ₃ . As a result, the-COOH, -COOCH-of the copolymer can be used ₃ 、-CH ₂ OH、-COF、-CF＝CF ₂ 、-CONH ₂ and-CF ₂ The total number of H (the number of functional groups) is easily adjusted to be within the above-mentioned range.

The fluorine-containing compound is not particularly limited, and examples thereof include a fluorine radical source that generates a fluorine radical under the fluorination treatment conditions. As the fluorine radical source, F may be mentioned ₂ Gas, coF ₃ 、AgF ₂ 、UF ₆ 、OF ₂ 、N ₂ F ₂ 、CF ₃ OF, fluorinated halogens (e.g. IF ₅ 、ClF ₃ ) Etc.

F ₂ The fluorine radical source such as gas may be at a concentration of 100%, but is preferably inactive from the viewpoint of safetyThe gas is mixed and diluted to 5 to 50 mass%, more preferably 15 to 30 mass%. The inert gas may be nitrogen, helium, argon, or the like, and nitrogen is preferable from the viewpoint of economy.

The conditions of the fluorination treatment are not particularly limited, and the copolymer in a molten state may be brought into contact with the fluorine-containing compound, but may be usually conducted at a temperature of 20 to 240℃and more preferably 100 to 220℃below the melting point of the copolymer. The fluorination treatment is generally carried out for 1 to 30 hours, preferably 5 to 25 hours. The fluorination treatment preferably involves reacting the copolymer which has not been subjected to the fluorination treatment with fluorine gas (F ₂ Gas) contact.

In addition, in the production method of the copolymer contained in the injection-molded article of the present invention, the production method described in Japanese patent application laid-open No. 2020-97750 is also preferably used.

In the method for producing the copolymer contained in the injection-molded article of the present invention, in each step for producing the copolymer to be injection-molded, such as a polymerization step, a granulation step, a cleaning step, a drying step, a transfer step, a storage step, a granulation step, a fluorination step, and a product filling step, it is preferable that the material and the copolymer used for production are not brought into contact with the metal surfaces of each equipment and piping as much as possible, and that the material having a low metal content be used for production. By such a method, finally, an injection-molded article with a further reduced metal elution amount to 50 mass% hydrofluoric acid can be easily obtained.

In the method for producing the copolymer contained in the injection-molded article of the present invention, clean and dry air is preferably used as the air for drying the copolymer and the air for transferring the copolymer between the respective devices. By such a method, finally, an injection-molded article with a further reduced metal elution amount to 50 mass% hydrofluoric acid can be easily obtained.

By producing the copolymer as described above, for example, a copolymer having a metal content of 100ng/1g or less as measured by the ashing method can be obtained. The metal content of the copolymer to be used for injection molding is preferably 100ng/1g or less, more preferably 60ng/1g or less, further preferably 50ng/1g or less, particularly preferably 40ng/1g or less, most preferably 30ng/1g or less, and the lower limit is not particularly limited and may be 1ng/1g or more, from the viewpoint that an injection molded article having a further reduced metal elution amount to 50 mass% hydrofluoric acid can be easily obtained.

As a method for measuring the metal content in the copolymer, the following method can be used: ashing the copolymer in a reaction cup located in an atomization portion of an atomic absorption spectrophotometer, and measuring a metal content using the atomic absorption spectrophotometer; a method in which the copolymer is measured in a platinum crucible, ashed using a gas burner or an electric furnace, and the ash is dissolved in an acid, and then the metal content is measured using an ICP emission analyzer or a flameless atomic absorption spectrophotometer; etc.

The copolymer obtained as described above is injection molded to obtain an injection molded article.

In a method for producing an injection-molded article by injection-molding a copolymer using an injection molding machine comprising a barrel and a screw accommodated in the barrel, the copolymer is produced by using a FAVE unit having a content, MFR and melting point within the above ranges and being 10 per unit ⁶ The copolymer having 20 or less functional groups, preferably 15 or less, of carbon atoms in the main chain can be suitably produced into the injection-molded article of the present application.

The production method of the present application has the above-described configuration, and therefore, it is possible to easily obtain an injection-molded article having a reduced amount of fluoride ions released into water, and further, it is possible to easily produce an injection-molded article having a complicated shape, for example, an injection-molded article such as a female joint or a nut.

In the production method of the present application, the temperature of the cylinder is adjusted to 385 to 395 ℃, whereby an injection molded article having a further reduced amount of fluoride ions released into water can be obtained. The cartridge temperature is preferably 392 ℃ or less, more preferably 390 ℃ or less.

In the production method of the present application, a cylinder subjected to Ni plating or a cylinder made of a Ni-based alloy is used as the cylinder; as the screw, a screw formed of a Ni-based alloy and having a plasticizing head provided at the tip was used, whereby an injection molded body with a reduced metal elution amount to 50 mass% hydrofluoric acid was obtained.

The shape of the copolymer to be supplied to the injection molding machine is not particularly limited, and a copolymer in the form of powder, pellet, or the like may be used.

As the injection molding machine, a known injection molding machine can be used. The copolymer ejected from the nozzle of the injection molding machine typically flows through the sprue and runner, through the sprue and into the mold cavity, filling the mold cavity. A runner and a gate are formed in a mold for injection molding, and a mold cavity for forming an injection molded body is formed.

The shape of the inlet is not particularly limited, and may be circular, rectangular, trapezoidal, or the like. The shape of the flow channel is not particularly limited, and may be circular, rectangular, trapezoidal, or the like. The runner system is not particularly limited, and may be a cold runner or a hot runner. The gate method is not particularly limited, and may be a direct gate, a side gate, a submerged gate, or the like. The number of gates relative to the mold cavity is not particularly limited. Either a mold having a single point gate structure or a mold having a multi point gate structure may be used. The number of die cavities (the number of cavities) of the die is preferably 1 to 64.

The injection-molded article of the present invention can be used for various purposes. The injection molded article of the present invention may be, for example, nuts, bolts, joints, female joints, films, bottles, gaskets, pipes, hoses, pipes, valves, sheets, seals, gaskets, tanks, rollers, containers, taps, connectors, filter housings, filter covers, flow meters, pumps, wafer carriers, wafer cassettes, and the like.

The injection-molded article of the present invention is excellent in physical properties such as low water vapor permeability, low reagent permeability, abrasion resistance, mechanical properties, rigidity at high temperature, and the like, and also excellent in ozone resistance, and therefore can be suitably used for nuts, bolts, joints, gaskets, valves, taps, connectors, filter housings, filter covers, flow meters, pumps, and the like. For example, the present invention can be suitably used as a piping member (in particular, a valve case or a filter cover) for transferring a reagent or a flowmeter case having a flow path for a reagent in a flowmeter. The piping member and the flowmeter case of the present invention are excellent in physical properties such as low water vapor permeability, low reagent permeability, abrasion resistance, mechanical properties, rigidity at high temperature, and the like, and also excellent in ozone resistance. Further, the piping member and the flowmeter case of the present invention can be manufactured at an extremely high injection speed without corroding a mold for molding, even in the case of having a thin wall portion, and are excellent in appearance.

The injection molded article of the present invention can be suitably used as a compressed member such as a gasket or a gasket having excellent physical properties such as low water vapor permeability, low reagent permeability, abrasion resistance, mechanical properties, and rigidity at high temperatures, and also having excellent ozone resistance.

The injection molded article of the present invention can be suitably used as a bottle or tube excellent in physical properties such as low water vapor permeability, low reagent permeability, abrasion resistance, mechanical properties, rigidity at high temperature, and the like, and also excellent in ozone resistance. The bottle or tube of the present invention is not easily damaged in use.

The injection-molded article of the present invention is excellent in physical properties such as low water vapor permeability, low reagent permeability, abrasion resistance, mechanical properties, rigidity at high temperature, and ozone resistance. Thus, the injection molding of the present invention can be suitably used for a valve housing or a valve. The valve of the present invention can be manufactured at low cost and with extremely high productivity without corroding the mold, and is excellent in physical properties such as low vapor permeability, low reagent permeability, abrasion resistance, mechanical properties, rigidity at high temperature, and the like.

While the embodiments have been described above, it will be understood that various changes in form and details may be made therein without departing from the spirit and scope of the claims.

Examples

Next, embodiments of the present invention will be described with reference to examples, but the present invention is not limited to the examples.

The values of the experimental examples were measured by the following methods.

(content of monomer units)

The content of each monomer unit was measured by an NMR analyzer (for example, AVANCE300 high temperature probe manufactured by Bruker Biospin Co.).

(melt flow Rate (MFR))

The mass (G/10 minutes) of the polymer flowing out from a nozzle having an inner diameter of 2.1mm and a length of 8mm per 10 minutes was determined by using a melt index analyzer G-01 (manufactured by Toyo Seisakusho-Sho Co., ltd.) at 372℃under a 5kg load in accordance with ASTM D1238.

(melting point)

The melting point was determined from the melting curve peak generated during the 2 nd heating process by performing the 1 st heating from 200℃to 350℃at a heating rate of 10℃per minute using a differential scanning calorimeter (trade name: X-DSC7000, manufactured by Hitachi High-Tech Science Co., ltd.), then cooling from 350℃to 200℃at a cooling rate of 10℃per minute, and performing the 2 nd heating from 200℃to 350℃again at a heating rate of 10℃per minute.

(number of functional groups)

The pellets of the copolymer were cold-molded to prepare a film having a thickness of 0.25mm to 0.3 mm. By Fourier transform infrared Spectrum analysis device [ FT-IR (Spectrum One manufactured by Perkinelmer Co.)]The film was scanned 40 times and analyzed to obtain an infrared absorption spectrum and a differential spectrum from a fully fluorinated background spectrum without functional groups. The absorbance peak of the specific functional group shown by the differential spectrum was calculated for every 1X 10 in the sample according to the following formula (A) ⁶ Number of functional groups N of carbon atoms.

N＝I×K/t (A)

I: absorbance of light

K: correction coefficient

t: film thickness (mm)

For reference, regarding the functional groups in the present invention, the absorption frequency, molar absorptivity, and correction coefficient are shown in table 2. The molar absorptivity is determined from FT-IR measurement data of the low molecular weight model compound.

TABLE 2

Synthesis example 1

Pellets were obtained in the same manner as in example 1 of Japanese patent application laid-open No. 2020-97750, except that 49.0L of pure water, 40.7kg of perfluorocyclobutane, 1.61kg of perfluoro (propyl vinyl ether) (PPVE), 1.02kg of methanol, 0.041kg of 50% methanol solution in which Tetrafluoroethylene (TFE) was pushed in to 0.64MPa was changed to di-n-propyl peroxydicarbonate instead of di-sec-butyl peroxydicarbonate, 0.052kg of PPVE was added per 1kg of TFE supplied, and the polymerization time was changed to 18 hours. Using the resulting particles, PPVE content was determined by the method described above. The results are shown in Table 3.

The obtained pellets were placed in a vacuum vibration type reaction apparatus VVD-30 (manufactured by Dachuan origin Co., ltd.) and heated to 210 ℃. After evacuation, N for introduction ₂ F gas dilution to 20 vol% ₂ The gas is brought to atmospheric pressure. From F ₂ After 0.5 hour from the time of gas introduction, the mixture was once evacuated and F was introduced again ₂ And (3) gas. After 0.5 hour, the mixture was again evacuated and F was introduced again ₂ And (3) gas. Thereafter, F is as described above ₂ The gas introduction and evacuation operations were continued for 1 time within 1 hour, and the reaction was carried out at 210℃for 10 hours. After the reaction, the inside of the reactor was fully replaced with N ₂ And (3) ending the fluorination reaction by using the gas. Using the fluorinated pellets, various physical properties were measured by the above-described method. The results are shown in Table 3.

Synthesis example 2

Pellets were obtained in the same manner as in example 1 of Japanese patent application laid-open No. 2020-97750, except that 49.0L of pure water, 40.7kg of perfluorocyclobutane, 2.58kg of perfluoro (propyl vinyl ether) (PPVE), 2.24kg of methanol, 0.041kg of 50% methanol solution in which Tetrafluoroethylene (TFE) was pushed in to 0.64MPa was changed to di-n-propyl peroxydicarbonate instead of di-sec-butyl peroxydicarbonate, 0.071kg of PPVE was added per 1kg of TFE supplied, and the polymerization time was changed to 19 hours. Using the pellets obtained, the PPVE content was determined by the method described above. The results are shown in Table 3.

Fluorinated pellets were obtained in the same manner as in Synthesis example 1 except that the obtained pellets were used. The results are shown in Table 3.

Synthesis example 3

Pellets were obtained in the same manner as in example 1 of Japanese patent application laid-open No. 2020-97750, except that 49.0L of pure water, 40.7kg of perfluorocyclobutane, 1.90kg of perfluoro (propyl vinyl ether) (PPVE), 1.50kg of methanol, 0.041kg of 50% methanol solution in which Tetrafluoroethylene (TFE) was pushed in to 0.64MPa was changed to di-n-propyl peroxydicarbonate instead of di-sec-butyl peroxydicarbonate, 0.057kg of PPVE was added per 1kg of TFE supplied, and the polymerization time was changed to 18 hours. Using the pellets obtained, the PPVE content was determined by the method described above. The results are shown in Table 3.

Synthesis example 4

Pellets were obtained in the same manner as in example 1 of Japanese patent application laid-open No. 2020-97750, except that 49.0L of pure water, 40.7kg of perfluorocyclobutane, 2.12kg of perfluoro (propyl vinyl ether) (PPVE), 1.80kg of methanol, 0.041kg of 50% methanol solution in which Tetrafluoroethylene (TFE) was pushed in to 0.64MPa was changed to di-n-propyl peroxydicarbonate instead of di-sec-butyl peroxydicarbonate, 0.062kg of PPVE was added per 1kg of TFE supplied, and the polymerization time was changed to 19 hours. Using the pellets obtained, the PPVE content was determined by the method described above. The results are shown in Table 3.

Synthesis example 5

Pellets were obtained in the same manner as in example 1 of Japanese patent application laid-open No. 2020-97750, except that the amount of pure water was changed to 51.8L, perfluorocyclobutane was changed to 40.9kg, perfluoro (propyl vinyl ether) (PPVE) was changed to 2.75kg, methanol was changed to 2.38kg, tetrafluoroethylene (TFE) was changed to 0.64MPa, 50% methanol solution of di-n-propyl peroxydicarbonate was changed to 0.051kg instead of di-sec-butyl peroxydicarbonate, PPVE was added to 1kg of TFE, and polymerization was terminated when the additional amount of TFE was 40.9kg, to obtain 43.3kg of dry powder. Using the pellets obtained, the PPVE content was determined by the method described above. The results are shown in Table 3.

Fluorinated pellets were obtained in the same manner as in Synthesis example 1, except that the temperature of the vacuum vibration type reaction apparatus was changed to 170℃and the reaction was changed to 5 hours at 170 ℃. The results are shown in Table 3.

Synthesis example 6

Pellets were obtained in the same manner as in example 1 of Japanese patent application laid-open No. 2020-97750, except that the amount of pure water was changed to 26.6L, the amount of perfluoro (propyl vinyl ether) (PPVE) was changed to 1.25kg, the amount of methanol was changed to 2.17kg, the amount of Tetrafluoroethylene (TFE) was changed to 0.58MPa, and the amount of 50% methanol solution of di-n-propyl peroxydicarbonate was changed to 0.044kg instead of di-sec-butyl peroxydicarbonate, and the amount of PPVE was changed to 0.044kg per 1kg of TFE supplied, and the polymerization time was changed to 8.5 hours. Using the pellets obtained, the PPVE content was determined by the method described above. The results are shown in Table 3.

Synthesis example 7

Pellets were obtained in the same manner as in example 1 of Japanese patent application laid-open No. 2020-97750, except that the amount of pure water was changed to 26.6L, the amount of perfluoro (propyl vinyl ether) (PPVE) was changed to 1.32kg, the amount of methanol was changed to 2.20kg, the amount of Tetrafluoroethylene (TFE) was changed to 0.58MPa, and the amount of 50% methanol solution of di-n-propyl peroxydicarbonate was changed to 0.044kg instead of di-sec-butyl peroxydicarbonate, and the amount of PPVE was changed to 0.046kg per 1kg of TFE supplied, and the polymerization time was changed to 8.5 hours. Using the pellets obtained, the PPVE content was determined by the method described above. The results are shown in Table 3.

Synthesis example 8

Pellets were obtained in the same manner as in example 1 of Japanese patent application laid-open No. 2020-97750, except that 49.0L of pure water, 40.7kg of perfluorocyclobutane, 1.90kg of perfluoro (propyl vinyl ether) (PPVE), 3.40kg of methanol, 0.041kg of 50% methanol solution in which Tetrafluoroethylene (TFE) was pushed in to 0.64MPa was changed to di-n-propyl peroxydicarbonate instead of di-sec-butyl peroxydicarbonate, 0.057kg of PPVE was added per 1kg of TFE supplied, and the polymerization time was changed to 19 hours. Using the pellets obtained, the PPVE content was determined by the method described above. The results are shown in Table 3.

Synthesis example 9

Pellets were obtained in the same manner as in example 1 of Japanese patent application laid-open No. 2020-97750, except that the amount of pure water was changed to 51.8L, perfluorocyclobutane was changed to 40.9kg, perfluoro (propyl vinyl ether) (PPVE) was changed to 3.47kg, methanol was changed to 3.28kg, tetrafluoroethylene (TFE) was changed to 0.64MPa, 50% methanol solution of di-n-propyl peroxydicarbonate was changed to 0.026kg instead of di-sec-butyl peroxydicarbonate, PPVE was added to 1kg of TFE, polymerization was terminated when the additional amount of TFE was 40.9kg, and 43.8kg of dry powder was obtained. Using the pellets obtained, the PPVE content was determined by the method described above. The results are shown in Table 3.

TABLE 3

TABLE 3 Table 3

The expression "< 6" in Table 3 means that the number of functional groups is less than 6.

Experimental example 1 to Experimental example 5 and comparative examples 2 to comparative example 5

The molding was performed in Sup>A class 10000 clean room using an injection molding machine (SE 50 EV-Sup>A, manufactured by sumitomo heavy machinery industries, inc.). As the screw of the injection molding machine, a screw having a plasticizing head provided at a screw head is used, and the screw and the barrel of the injection molding machine are made of a Ni-based alloy. As shown in Table 4, the highest temperature of the cylinder of the injection molding machine was set to 200℃for the mold temperature and 20mm/s for the injection speed, and the copolymer was injection molded to prepare a sheet-like injection molded article (40 mm. Times.40 mm. Times.0.5 mmt). As the mold, a mold (40 mm×40mm×0.5mmt,4 cavities, side gates) in which Ni plating was performed on HPM38 was used.

The injection molding of the copolymer was repeated 100 times, the molding machine was stopped and the heater was turned off, and after 22 hours, the molding machine was operated again, and the injection molding of the polymer was repeated 100 times.

Experimental example 6 and comparative example 1

The molding was performed using an injection molding machine (SE 50EV-A, manufactured by Sumitomo mechanical industries Co., ltd.). As the screw of the injection molding machine, a screw provided with a screw tip composed of a screw head, a check ring, and a seal ring (screw 3 pieces), was used, the screw and the barrel of the injection molding machine were made of stainless steel, and Cr plating was performed on the surfaces. As shown in Table 4, the highest temperature of the cylinder of the injection molding machine was set to 200℃and the injection speed was set to 20mm/s, and the copolymer was injection molded to prepare a sheet-like injection molded article (40 mm. Times.40 mm. Times.0.5 mmt). As a mold, a mold made of HPM38 (40 mm. Times.40 mm. Times.0.5 mmT,4 cavities, side gates) was used.

Using the injection-molded articles obtained in the experimental examples and comparative examples, the fluoride ion elution amount and the metal elution amount were measured by the following methods. The results are shown in Table 4.

(measurement of the amount of fluoride ion elution)

The amount of fluoride ion eluted was measured using an injection-molded article obtained by the 199 th injection molding. 4 sheet-like injection molded articles (40 mm. Times.40 mm. Times.0.5 mmt) were cut out from the runners of the obtained injection molded articles using scissors made of ceramic. The 4 sheet-like injection-molded bodies were immersed in 14g of pure water, heated at 121℃for 1 hour by a sterilizer, and then the injection-molded bodies were taken out of the obtained water, and the concentration of fluorine ions in the remaining water was measured by a fluorine ion meter. The fluoride ion elution amount per unit surface area of the injection-molded article was calculated from the obtained measurement value according to the following formula.

Fluoride ion elution amount (. Mu.g/m) ² ) Measurement value (. Mu.g/g). Times.pure water amount (g)/total surface area of 4 injection-molded bodies (m) ² )

(measurement of amount of eluted metal)

The amount of fluoride ion eluted was measured using an injection-molded article obtained by the 200 th injection molding. As a container used for the measurement, a PFA container immersed in 50 mass% hydrofluoric acid at 25 ℃ for 7 days and then rinsed with ultrapure water was used.

4 sheet-like injection molded articles (40 mm. Times.40 mm. Times.0.5 mmt) were cut out from the runners of the obtained injection molded articles using scissors made of ceramic. In a PFA container, all 4 sheet-shaped injection-molded articles were immersed in 50 mass% hydrofluoric acid at 25 ℃ for 24 hours, and then taken out. Next, the PFA container was placed in a water bath, heated to completely evaporate water from hydrofluoric acid, and then 0.1 equivalent of an aqueous nitric acid solution was added to prepare a measurement solution. Meanwhile, in the PFA container, hydrofluoric acid was left alone at 25 ℃ for 24 hours, and a reference solution was prepared by the same method as described above.

The concentrations of iron, chromium, and nickel (metal concentrations) in the measurement solution and the reference solution were measured using an ICP emission analyzer (manufactured by SPECTROBLUE TI, SPECTRO Analytical Instruments GmbH). The metal elution amount per unit surface area of the injection-molded article was calculated from the obtained measurement value according to the following formula.

Metal elution amount (. Mu.g/m) ² ) = [ metal concentration in measurement solution (ng/g) -metal concentration in reference solution (ng/g)]X50% by mass hydrofluoric acid amount (g) X0.001 (. Mu.g/ng)/total surface area (m) of 4 injection molded bodies ² )

Experimental example 7 to Experimental example 10 and comparative example 6 to comparative example 9

The molding was performed in a class 10000 clean room using an injection molding machine (IS 130FI, manufactured by Toshiba machinery Co., ltd.). As the screw of the injection molding machine, a screw having a plasticizing head provided at a screw head is used, and the screw and the barrel of the injection molding machine are made of a Ni-based alloy. The highest temperature of the cylinder of the injection molding machine was 390 ℃, the mold temperature was 200 ℃, the injection speed was 5mm/s, and the copolymer was injection molded to prepare a sheet-like injection molded article (130 mm. Times.130 mm. Times.3 mmt). As the mold, a mold (130 mm×130mm×3mmt, side gate, gate-up flow length exceeding 130 mm) in which Ni plating was performed on HPM38 was used.

Fluoride ion elution amount and metal elution amount were measured by the above-described methods using the injection-molded articles obtained in the experimental examples and comparative examples. The results are shown in Table 5.

The injection moldability of the copolymers used in examples 7 to 10 and comparative examples 6 to 9 was evaluated by the following methods. The results are shown in Table 5.

(injection moldability)

The obtained injection-molded article was observed and evaluated according to the following criteria. The presence or absence of surface roughness was confirmed by contacting the surface of the injection-molded article.

3: the surface was smooth in its entirety, and no flow mark was observed in the entirety of the molded article

2: the roughness was observed on the surface in the range of 1cm from the position where the gate of the mold was located, but the surface in the other range was entirely smooth, and no flow mark was observed on the entire molded article

1: roughness was observed on the surface in a range of 1cm from the position of the gate of the mold, and flow marks were observed in a range of 1cm from the position of the gate of the mold, but the surface in the other range was entirely smooth, and no flow marks were observed

0: roughness was confirmed on the surface within 4cm from the position of the gate of the mold, and flow marks were observed within 4cm from the position of the gate of the mold

Further, ozone exposure tests were carried out using the injection molded articles obtained in the experimental examples and the comparative examples. The injection-molded articles obtained in the experimental examples and comparative examples were evaluated by the following methods. The results are shown in tables 4 and 5.

(ozone exposure test)

Ozone gas (ozone/oxygen=10/90 vol%) generated by an ozone generating apparatus (trade name: SGX-a11MN (modified), manufactured by sumitomo fine industries, co.) was connected to a container made of PFA containing ion-exchanged water, and after bubbling the ion-exchanged water and adding water vapor to the ozone gas, the sample was exposed to humid ozone gas at room temperature through a groove made of PFA containing a sheet-like injection molded body at 0.7 liter/min. After 120 days from the initial exposure, the sample was taken out, the surface was lightly rinsed with ion-exchanged water, and then a portion having a depth of 5 μm to 200 μm from the sample surface was observed at a magnification of 100 times by using a transmission optical microscope, taken together with a standard scale, and the surface of the sample was measured every 1mm ² The number of cracks having a length of 10 μm or more was evaluated according to the following criteria.

O: the number of cracks is less than 10

Delta: the number of cracks exceeds 10 and is less than 50

X: the number of cracks exceeds 50

(vapor permeability)

After the sheet-like injection-molded body was left at 60℃for 24 hours, a test piece was produced from the injection-molded body. A sheet-like test piece having a thickness of about 0.2mm was produced using the pellets and a hot press molding machine. In the test cup (penetration area 7.065 cm) ² ) 10g of water was put therein, covered with a sheet-like test piece, and fastened and sealed with a PTFE gasket interposed therebetween. The sheet-like test piece was brought into contact with water, kept at 95℃for 60 days, and taken out,the mass reduction was measured after 2 hours of standing at room temperature. By measuring the water vapor permeability (g/m ² )。

Water vapor transmission rate (g/m) ² ) =mass reduction (g)/transmission area (m ² )

(methyl ethyl ketone (MEK) transmittance)

After the sheet-like injection-molded body was left at 60℃for 24 hours, a sheet-like test piece was produced from the injection-molded body. In a test cup (permeation area 12.56 cm) ² ) 10g of MEK was placed in the container, and the container was covered with a sheet-like test piece, and fastened and sealed with a PTFE gasket interposed therebetween. The sheet-like test piece was brought into contact with MEK, kept at a temperature of 60℃for 60 days, taken out, and left at room temperature for 1 hour to measure the mass reduction. The MEK transmittance (g/m) was determined by the following formula ² )。

MEK Transmission (g/m) ² ) =mass reduction (g)/transmission area (m ² )

(abrasion test)

The sheet-like injection-molded article was left at 60℃for 24 hours and then used as a test piece. A test piece was fixed to a test bed of a Taber abrasion tester (No. 101 Taber abrasion tester, manufactured by An Tian Sema Co., ltd.) and abrasion test was performed using the Taber abrasion tester under conditions of a load of 500g, abrasion wheel CS-10 (20 revolutions ground with grinding paper # 240), and a rotational speed of 60 rpm. The weight of the test piece after 1000 revolutions was measured, and the test piece weight was further measured after 10000 revolutions with the same test piece. The abrasion loss was determined by the following formula.

Abrasion loss (mg) =m1-M2

M1: test piece weight after 1000 revolutions (mg)

M2: test piece weight after 10000 revolutions (mg)

(95 ℃ C. Load deflection rate)

After the sheet-like injection-molded body was left at 60℃for 24 hours, a test piece of 80mm X10 mm was cut out from the injection-molded body, and heated at 100℃for 20 hours by an electric furnace. Except for using the obtained test piece, the test was conducted under the conditions of a test temperature of 30 to 150℃and a heating rate of 120℃per hour, a bending stress of 1.8MPa, and a flat winding method by a thermal distortion tester (manufactured by An Tian Sema Co., ltd.) according to the method described in JIS K-K7191. The load deflection was obtained by the following method. The sheet having a small deflection under load at 95℃is excellent in rigidity at high temperatures.

Load deflection (%) =a2/a1×100

a1: thickness of test piece before test (mm)

a2: deflection (mm) at 95 ℃C

The results are shown in tables 4 and 5.

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Experimental example 11 to Experimental example 14, comparative example 10 to comparative examples 12 and 14

(production of nut)

The copolymers of synthesis examples 1 to 4 and 6 to 9 were injection molded in the same manner as in experimental example 1 except that the highest temperature of the cylinder was changed to 390 ℃, the mold temperature was changed to 150 ℃, and the injection speed was changed to 5mm/s, thereby producing nuts having the shapes shown in fig. 1. As the mold, a mold (cap nut, thread M (lower inner diameter) =36 mm, e (hexagonal side) =46.2 mm, S (outer diameter) =40 mm, D (upper inner diameter) =27 mm, H (height) =30 mm, H (inner height) =24 mm, single point side gate) in which Ni plating was performed on HPM38 was used.

Comparative example 13

(production of nut)

A nut having a shape shown in fig. 1 was produced by injection molding the copolymer of synthesis example 5 in the same manner as in comparative example 1 except that the highest temperature of the cylinder was changed to 400 ℃, the mold temperature was changed to 150 ℃, and the injection speed was changed to 5 mm/s. As the mold, a mold made of HPM38 (cap nut, thread tooth m=36 mm, e=46.2 mm, s=40 mm, d=27 mm, h=30 mm, h=24 mm, single point side gate) was used.

The fluorine ion elution amount and the metal elution amount were measured by the above-described methods using the nuts obtained in the experimental examples and the comparative examples. The results are shown in Table 6.

The nuts obtained in the experimental examples and comparative examples were evaluated by the following methods. The results are shown in Table 6.

(transferability)

The transferability of the thread portion of the obtained nut was visually confirmed.

O: the shape of the mold is reliably transferred to the injection molding body, and a thread part with a desired shape is formed

X: a part of the shape of the mold was not transferred to the injection-molded article, and a thread having a shape different from the desired shape was observed

(tensile test)

A nut strength failure test was performed to measure the strength of the nut. Tensile test A Tensilon universal tester (UCT-500 manufactured by ORIENTEC) was used, an upper clamp having a disk shape was hung on the top surface of a nut, a lower clamp having a screw shape was inserted into the nut, the tensile test was performed under conditions that the tensile speed was 0.5mm/min and 1mm between the upper clamp and the lower clamp, the upper part of the nut was visually observed in the tensile test, and the tensile test was stopped at the moment when a crack was generated. The load (breaking load) at the time of stopping the tensile test was measured and evaluated according to the following criteria.

O: fracture load of 440N or more

Delta: breaking load of 430-440N

X: load at break 430N or less

(ozone exposure test)

The number of cracks was measured in the same manner as in the ozone exposure test described above except that the sample was changed from the sheet-like injection molded body to the nut, and the evaluation was performed on the same basis.

The results are shown in Table 6.

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Claims

1. An injection molded article comprising a copolymer comprising tetrafluoroethylene units and fluoro (alkyl vinyl ether) units, wherein,

the content of the fluoro (alkyl vinyl ether) unit of the copolymer is 4.7 to 7.0 mass% relative to the total monomer units,

the melt flow rate of the copolymer at 372 ℃ is 11.0g/10 min-22.0 g/10 min,

the melting point of the copolymer is 296-305 ℃,

the amount of fluoride ion released from the injection-molded article into water was 7500. Mu.g/m ² The following is given.

2. The injection-molded article according to claim 1, wherein the amount of elution of fluorine ions from the injection-molded article to water is 5500. Mu.g/m ² The following is given.

3. The injection-molded article according to claim 1 or 2, wherein a metal elution amount from the injection-molded article to 50 mass% hydrofluoric acid is 200 μg/m ² The following is given.

4. The injection-molded article according to any one of claims 1 to 3, wherein the fluoro (alkyl vinyl ether) unit of the copolymer is a perfluoro (propyl vinyl ether) unit.

5. The injection-molded article according to any one of claims 1 to 4, wherein the content of the fluoro (alkyl vinyl ether) unit of the copolymer is 4.9 to 6.6 mass% relative to the total monomer units.

6. The injection-molded article according to any one of claims 1 to 5, wherein the copolymer has a melt flow rate at 372 ℃ of 13.0g/10 min to 20.0g/10 min.

7. An injection formulation according to any one of claims 1 to 6A molded body, wherein each 10 of the copolymer ⁶ The number of functional groups having the number of main chain carbon atoms is 20 or less.

8. The injection-molded body according to any one of claims 1 to 7, which is a nut.

9. A method for producing an injection-molded article according to any one of claims 1 to 8, wherein,

the copolymer is injection molded using an injection molding machine having a barrel and a screw accommodated in the barrel to obtain the injection molded body.

10. The production method according to claim 9, wherein the temperature of the copolymer in the cylinder is adjusted to 385 ℃ to 395 ℃.

11. The production method according to claim 9 or 10, wherein as the cylinder, a cylinder subjected to Ni plating or a cylinder formed of a Ni-based alloy is used; as the screw, a screw formed of a Ni-based alloy and provided with a plasticizing head at the tip is used.