JP2016124909A - Method for producing fluorine-containing resin crosslinked body, method for producing molding, and fluorine-containing resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a fluorine-containing resin crosslinked body which can crosslink a fluorine-containing resin with a simple method, and has small creep displacement and has high mechanical strength of the obtained molding; a method for producing the molding; and a fluorine-containing resin composition.SOLUTION: A method for producing a fluorine-containing resin crosslinked body having a crosslinked structure obtained by ionically bonding carboxylate ions derived from any one or both of an acid anhydride group and a carboxyl group, and divalent or more metal ions includes: heating a fluorine-containing resin composition containing a fluorine-containing resin (A) having any one or both of the acid anhydride group and the carboxyl group and a compound (B) for forming a specific crosslinked structure to a melting point of the fluorine-containing resin (A) or higher, and forming the crosslinked structure.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing a crosslinked fluorine-containing resin, a method for producing a molded article, and a fluorine-containing resin composition.

  Fluorine-containing resins are excellent in solvent resistance, low dielectric properties, low surface energy properties, non-adhesiveness, weather resistance, etc., and are therefore used in various applications that cannot be used in general-purpose resin products. In particular, in applications where molded articles containing resin are placed in harsh, high-temperature environments, fluororesins are preferred because the resin does not decompose even at high temperatures and the mechanical strength must not be impaired. ing.

  The fluorine-containing resin may be subjected to a crosslinking treatment in order to further improve the mechanical strength against high temperatures. For example, Patent Document 1 discloses a fluorine-containing resin crosslinked product obtained by crosslinking a fluorine-containing resin composition containing an ethylene-tetrafluoroethylene copolymer (hereinafter also referred to as “ETFE”) by electron beam irradiation. .

JP-A-7-169340

However, the invention described in Patent Document 1 is complicated because it takes time and cost for the electron beam irradiation process. The present inventors have also found that the molded body obtained based on the invention of Patent Document 1 cannot achieve both a small creep displacement and a high mechanical strength. That is, when the electron beam is applied at a high irradiation degree, the creep displacement becomes small, but the main chain of the fluororesin is cut and the mechanical strength is lowered.
The present invention is a method for producing a fluororesin crosslinked product, a method for producing a molded product, and a fluororesin composition, in which the fluororesin can be crosslinked by a simple method, and the resulting molded product has small creep displacement and high mechanical strength. The purpose is to provide goods.

The present invention provides a method for producing a cross-linked fluororesin having the following constitutions [1] to [11], a method for producing a molded product, and a fluororesin composition.
[1] A method for producing a crosslinked fluororesin having a crosslinked structure in which a carboxylate ion derived from one or both of an acid anhydride group and a carboxyl group and a metal ion having a valence of 2 or more are ionically bonded. A fluorine-containing resin composition comprising a fluorine-containing resin (A) having either one or both of an acid anhydride group and a carboxy group and a crosslinked structure-forming compound (B), the fluorine-containing resin (A) When the carboxylic acid ion is derived from an acid anhydride group, the crosslinked structure forming compound (B) is converted into the following compound (B1), the following compound ( B1) and the following compound (B2), the following compound (B2) and the following compound (B3), or the following compound (B1), the following compound (B2) and the following compound (B3), When the acid ion is derived from a carboxy group, the compound for forming a crosslinked structure (B) is the following compound (B1), the following compound (B2), or the following compound (B1) and the following compound (B2). A process for producing a crosslinked fluororesin, characterized by
(B1) A compound containing a divalent or higher valent metal ion source capable of ion-bonding with two or more carboxylate ions and capable of opening an acid anhydride group.
(B2) A compound containing a divalent or higher valent metal ion source capable of ion-bonding with two or more carboxylate ions (excluding the compound (B1)).
(B3) A compound capable of ring opening of an acid anhydride group (excluding the compound (B1)).
[2] In the fluorine-containing resin composition, the molar concentration of the acid anhydride group and the carboxyl group that the fluorine-containing resin (A) has, and the molar concentration of the metal that the compound for forming a crosslinked structure (B) has, The manufacturing method of the fluororesin crosslinked body of [1] which satisfy | fills following Formula (1).
0.01 ≦ (Z × n) / (X + 2Y) ≦ 1,000 (1)
[In Formula (1), Z is the molar concentration (mol / g) of the metal which the said compound for bridge | crosslinking structure formation (B) contained in the said fluororesin composition has, n is the said metal and said metal ion. X is the molar concentration (mol / g) of the carboxy group of the fluororesin (A) contained in the fluororesin composition, and Y is the fluororesin composition. It is the molar concentration (mol / g) of the acid anhydride group of the fluororesin (A) contained in the product. ]
[3] The method for producing a crosslinked fluororesin according to [1] or [2], wherein the fluororesin (A) has a unit based on a fluoroolefin.
[4] The method for producing a crosslinked fluororesin according to [3], wherein the fluororesin (A) further has a unit based on an olefin or a unit based on perfluorovinyl ether.
[5] The fluororesin (A) is at least selected from the group consisting of an ethylene-tetrafluoroethylene copolymer, a tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer, and a tetrafluoroethylene-hexafluoropropylene copolymer. The manufacturing method of the fluororesin crosslinked body in any one of [1]-[4] which is 1 type.
[6] The method for producing a crosslinked fluororesin according to any one of [1] to [5], wherein the crosslinked structure is formed by melt-kneading the fluororesin composition.

[7] A method for producing a molded body, characterized in that a molded body is obtained by melt-molding the fluororesin crosslinked body according to any one of the above [1] to [6]. .
[8] The method for producing a molded body according to [7], wherein the molded body is a wire covering material.
[9] Used for the production of a cross-linked fluororesin having a cross-linked structure in which a carboxylate ion derived from one or both of an acid anhydride group and a carboxy group and a divalent or higher valent metal ion are ionically bonded. A fluorine-containing resin composition comprising a fluorine-containing resin (A) having one or both of an acid anhydride group and a carboxy group and a compound for forming a crosslinked structure (B), wherein the carboxylate ion is acid anhydride When derived from a physical group, the compound for forming a crosslinked structure (B) is the following compound (B1), the following compound (B1) and the following compound (B2), the following compound (B2) and the following compound (B3), or In the case where the following compound (B1), the following compound (B2) and the following compound (B3) are derived from a carboxy group, the compound for forming a crosslinked structure (B) is the following compound (B1), the following compound (B2), or a fluorine-containing resin composition which is a following compound (B1) and the following compound (B2).
(B1) A compound containing a divalent or higher valent metal ion source capable of ion-bonding with two or more carboxylate ions and capable of opening an acid anhydride group.
(B2) A compound containing a divalent or higher valent metal ion source capable of ion-bonding with two or more carboxylate ions (excluding the compound (B1)).
(B3) A compound capable of ring opening of an acid anhydride group (excluding the compound (B1)).
[10] The molar concentration of the acid anhydride group and the carboxyl group that the fluorine-containing resin (A) has and the molar concentration of the metal that the compound (B) for forming a crosslinked structure satisfy the following formula (1): [9] The fluorine-containing resin composition.
0.01 ≦ (Z × n) / (X + 2Y) ≦ 1,000 (1)
[In Formula (1), Z is the molar concentration (mol / g) of the metal which the said compound for bridge | crosslinking structure formation (B) contained in the said fluororesin composition has, n is the said metal and said metal ion. X is the molar concentration (mol / g) of the carboxy group of the fluororesin (A) contained in the fluororesin composition, and Y is the fluororesin composition. It is the molar concentration (mol / g) of the acid anhydride group of the fluororesin (A) contained in the product. ]
[11] The fluororesin (A) is at least selected from the group consisting of an ethylene-tetrafluoroethylene copolymer, a tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer, and a tetrafluoroethylene-hexafluoropropylene copolymer. The fluorine-containing resin composition according to [9] or [10], which is one type.

  According to the present invention, a fluorine-containing resin can be crosslinked by a simple method, and the resulting molded article has a small creep displacement and high mechanical strength, a method for producing a crosslinked fluorine-containing resin, a process for producing a molded article, and a fluorine-containing resin A resin composition can be provided.

In this specification, the “monomer” means a compound having a radically polymerizable unsaturated group. “Fluorine-containing monomer” means a monomer having a fluorine atom. “Non-fluorinated monomer” means a monomer having no fluorine atom.
The “unit” means a part derived from a monomer that exists in the polymer and constitutes the polymer. The unit derived from the monomer resulting from addition polymerization of a monomer having a carbon-carbon unsaturated double bond is a divalent unit generated by cleavage of the unsaturated double bond. Moreover, what unitally converted the structure of a unit after polymer formation is also called a unit. Hereinafter, in some cases, a unit derived from an individual monomer is referred to as a name obtained by adding “unit” to the monomer name.
"Fluorine-containing resin" is a resin containing units based on fluorine-containing monomers.
An “acid anhydride group” is a group formed by dehydration condensation of two carboxy groups in the same molecule.

[Fluorine-containing resin composition]
The fluorine-containing resin composition of the present invention is a fluorine-containing resin having a cross-linked structure in which a carboxylate ion derived from one or both of an acid anhydride group and a carboxyl group is ionically bonded to a divalent or higher-valent metal ion. It is used for the production of a crosslinked resin.
The fluorine-containing resin composition contains a fluorine-containing resin (A) having either one or both of an acid anhydride group and a carboxy group, and a crosslinked structure forming compound (B). However, when the carboxylate ion is derived from an acid anhydride group, the crosslinked structure-forming compound (B) is represented by the following compound (B1), the following compound (B1), the following compound (B2), or the following compound (B2). And the following compound (B3), or the following compound (B1), the following compound (B2) and the following compound (B3). Moreover, when the said carboxylate ion originates in a carboxy group, the said compound (B) for bridge | crosslinking structure formation is the following compound (B1), the following compound (B2), or the following compound (B1) and the following compound (B2). ).
(B1) A compound containing a divalent or higher valent metal ion source capable of ion-bonding with two or more carboxylate ions and capable of opening an acid anhydride group.
(B2) A compound containing a divalent or higher valent metal ion source capable of ion-bonding with two or more carboxylate ions (excluding the compound (B1)).
(B3) A compound capable of ring opening of an acid anhydride group (excluding the compound (B1)).
Hereinafter, each component will be described.

(Fluorine-containing resin (A))
The fluororesin (A) has one or both of an acid anhydride group and a carboxy group (hereinafter also referred to as “functional group (I)”).

The content of the carbonyl group derived from the functional group (I) in the fluororesin (A) is preferably 10 to 60,000 with respect to 1 × 10 ⁶ main chain carbon atoms of the fluororesin (A). -50,000 are more preferable, and 100-10,000 are particularly preferable.
When the content of the carbonyl group derived from the functional group (I) in the fluororesin (A) is not less than the lower limit of the above range, the fluororesin (A) is excellent in crosslinking reactivity and is not more than the upper limit of the above range. When it is, it is excellent in the heat resistance of the fluororesin crosslinked body obtained.
The “main chain carbon number” means the number of carbon atoms in the longest carbon chain in the resin molecule.

The content of the functional group (I) can be measured by a method such as nuclear magnetic resonance (NMR) analysis or infrared absorption spectrum analysis. For example, using a method such as infrared absorption spectrum analysis as described in JP-A-2007-314720, the proportion of units having the functional group (I) in all units constituting the fluororesin (A) ( Mol%) and the content of the functional group (I) can be calculated from the ratio.
The content of the carbonyl group derived from the functional group (I) in the fluororesin (A) is such that the portion of the functional group (I) relating to the acid anhydride group is the content of the functional group (I). Calculated as twice the amount. The content of the carbonyl group derived from the functional group (I) in the fluororesin (A) is such that the portion related to the carboxy group in the functional group (I) is equal to the content of the functional group (I). Calculated. The content of the carbonyl group derived from the functional group (I) in the fluororesin (A) when both the acid anhydride group and the carboxy group are present as the functional group (I) in the fluororesin (A) is as follows: Calculate each separately and add both values.

The fluororesin (A) is not particularly limited as long as it has a fluorine atom and has a functional group (I). The functional group (I) may be present at the end of the main chain or may be present at the side chain. It can introduce | transduce into the principal chain terminal by selecting suitably the radical polymerization initiator, chain transfer agent, etc. which are used at the time of manufacture.
Since the fluororesin (A) is excellent in heat resistance, tetrafluoroethylene (hereinafter also referred to as “TFE”), chlorotrifluoroethylene (hereinafter also referred to as “CTFE”), vinyl fluoride, and vinylidene fluoride. It is preferable to have a unit based on a fluoroolefin such as C (hereinafter also referred to as “VdF”), trifluoroethylene, hexafluoropropylene (hereinafter also referred to as “HFP”). From the viewpoint of excellent moldability and heat resistance, it is preferable to further have units based on olefins such as ethylene and propylene (hereinafter also referred to as “olefin units”) or units based on perfluorovinyl ether.

Examples of the fluororesin (A) include ETFE, TFE-perfluoro (alkyl vinyl ether) copolymer (hereinafter also referred to as “PFA”), and TFE-HFP copolymer (hereinafter also referred to as “FEP”). , TFE-HFP-perfluoroalkyl vinyl ether copolymer (hereinafter also referred to as “EPE”), polychlorotrifluoroethylene (hereinafter also referred to as “PCTFE”) copolymer, ethylene-CTFE copolymer (hereinafter referred to as “EPE”). , "ECTFE"), polyvinylidene fluoride (hereinafter also referred to as "PVdF") type copolymer, polyvinyl fluoride (hereinafter also referred to as "PVF") type copolymer, TFE-HFP-. Among VdF copolymers (hereinafter also referred to as “THV”) and the like, those having a functional group (I) can be mentioned.
Among them, from the viewpoint of excellent moldability and heat resistance, a polymer having at least one selected from the group consisting of ETFE, PFA and FEP and having a functional group (I) is preferable, and a PFA having a functional group (I) is particularly preferable. preferable.

Specific examples of the fluororesin (A) include cyclic units having a unit (a) based on TFE and / or CTFE, a monomer having a carboxy group or an acid anhydride group, and a polymerizable unsaturated group in the ring. Based on units (b) based on hydrocarbon monomers (hereinafter also referred to as “cyclic hydrocarbon monomers”) and other monomers (excluding TFE, CTFE, monomers having a carboxy group and cyclic hydrocarbon monomers). And a copolymer containing the unit (c).
Here, the carboxy group or acid anhydride group of the unit (b) corresponds to the functional group (I) described above.

The monomer having a carboxy group refers to a compound having a carboxy group and a radically polymerizable unsaturated group.
Examples of the monomer having a carboxy group include acrylic acid, methacrylic acid, vinyl acetic acid, crotonic acid, itaconic acid, citraconic acid, maleic acid, fumaric acid, cinnamic acid, 5-norbornene-2,3-dicarboxylic acid, and these. And the like.

The cyclic hydrocarbon monomer refers to a polymerizable compound which is a cyclic hydrocarbon composed of one or more 5-membered or 6-membered rings and further has a carboxy group or an acid anhydride group and an intra-ring polymerizable unsaturated group. .
The cyclic hydrocarbon is preferably a cyclic hydrocarbon having one or more bridged polycyclic hydrocarbons. That is, a cyclic hydrocarbon composed of a bridged polycyclic hydrocarbon, a cyclic hydrocarbon condensed with two or more of the bridged polycyclic hydrocarbon, or a cyclic hydrocarbon condensed with a bridged polycyclic hydrocarbon and another cyclic hydrocarbon Preferably there is.

The cyclic hydrocarbon monomer has one or more endocyclic polymerizable unsaturated groups, that is, polymerizable unsaturated groups existing between carbon atoms constituting the hydrocarbon ring.
The cyclic hydrocarbon monomer further has an acid anhydride group (—CO—O—CO—). The acid anhydride group may be bonded to two carbon atoms constituting the hydrocarbon ring, or may be bonded to two carbon atoms outside the ring. Preferably, the acid anhydride group is bonded to two adjacent carbon atoms that constitute the ring of the cyclic hydrocarbon. Furthermore, a halogen atom, an alkyl group, a halogenated alkyl group, or other substituents may be bonded to the carbon atom constituting the ring of the cyclic hydrocarbon instead of the hydrogen atom.

  Specific examples of the cyclic hydrocarbon monomer include compounds represented by any one of formulas (2) to (9), maleic anhydride, and the like. Here, R in the formulas (3) and (6) to (9) is a halogen atom selected from the group consisting of a lower alkyl group having 1 to 6 carbon atoms, a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, A halogenated alkyl group in which a hydrogen atom in a lower alkyl group is substituted with a halogen atom. These may be used alone or in combination of two or more.

  The cyclic hydrocarbon monomers of the above formulas (2) to (9) are known compounds, and can be easily obtained by, for example, a method of heating cyclopentadiene and maleic anhydride without a catalyst, a method described in JP-A-6-73043, or the like. Can be manufactured. Moreover, a commercial item can be used.

  Among the cyclic hydrocarbon monomers, itaconic anhydride (hereinafter also referred to as “IAH”), citraconic anhydride (hereinafter also referred to as “CAH”), and 5-norbornene-2,3-dicarboxylic anhydride ( Hereinafter, at least one selected from the group consisting of “NAH”) is preferable. When at least one selected from the group consisting of IAH, CAH and NAH is used, the acid can be used without using a special polymerization method (see JP-A-11-19312) required when maleic anhydride is used. A fluorine-containing resin (A) having an anhydride group can be easily produced.

  The other monomer forming the unit (c) (excluding TFE, CTFE, a monomer having a carboxy group and a cyclic hydrocarbon monomer) may be a fluorine-containing monomer (excluding TFE and CTFE). It may be a fluorine-containing monomer (except for a monomer having a carboxy group and a cyclic hydrocarbon monomer) or a mixture thereof.

The fluorine-containing monomer forming the unit (c) is preferably a fluorine-containing compound having one polymerizable double bond. For example, the above-described fluoroolefin (excluding TFE and CTFE), CF ₂ = CFOR ^f1 ( R ^f1 is a perfluoroalkyl group having 1 to 10 carbon atoms and may contain an oxygen atom between carbon atoms.), CF ₂ = CFOR ^f ₂ SO ₂ X ¹ (where R ^f2 is a carbon atom having 1 to 10 carbon atoms) A perfluoroalkylene group which may contain an oxygen atom between them, X ¹ is a halogen atom or a hydroxyl group.), CF ₂ = CFOR ^{f 3} CO ₂ X ² (where R ^f3 has 1 to 10 carbon atoms and an oxygen atom between carbon atoms) which may contain a perfluoroalkylene group, ^{X 2} is an alkyl group having 3 or less carbon _{atoms.), CF 2 = CF (} CF 2) p OCF = CF (Here, p is 1 or ^{_{2.), CH 2 = CX}} 3 (CF 2) q X 4 ( however, ^{X 3} is a hydrogen atom or a fluorine atom, q is 2 to 10 integer, ^{X 4} is a hydrogen atom or fluorine Atom)) and perfluoro (2-methylene-4-methyl-1,3-dioxolane) and the like.

Among these fluorine-containing monomers, at least one selected from the group consisting of VdF, HFP, CF ₂ = CFOR ^f1 and CH ₂ = CX ³ (CF ₂ ) _q X ⁴ is preferable, and HFP and CF ₂ = CFOR ^f1 are particularly preferable preferable.
Examples of CF ₂ = CFOR ^f1 include CF ₂ = CFOCF ₂ CF ₃ , CF ₂ = CFOCF ₂ CF ₂ CF ₃ , CF ₂ = CFOCF ₂ CF ₂ CF ₂ CF ₃ CF ₂ = CFO (CF ₂ ) ₈ F, and the like. CF ₂ = CFOCF ₂ CF ₂ CF ₃ (hereinafter also referred to as “PPVE”) is preferable.
As CH ₂ = CX ³ (CF ₂ ) _q X ⁴ , CH ₂ = CH (CF ₂ ) ₂ F, CH ₂ = CH (CF ₂ ) ₃ F, CH ₂ = CH (CF ₂ ) ₄ F, CH ₂ ═CF (CF ₂ ) ₃ H, CH ₂ ═CF (CF ₂ ) ₄ H, and the like, and CH ₂ ═CH (CF ₂ ) ₄ F and CH ₂ ═CH (CF ₂ ) ₂ F are preferable.

As the non-fluorine-containing monomer (excluding the monomer having a carboxy group and the cyclic hydrocarbon monomer) forming the unit (c), a non-fluorine-containing compound having one polymerizable double bond is preferable. Examples thereof include vinyl esters such as olefin and vinyl acetate. These may be used alone or in combination of two or more.
Among these, ethylene, propylene and vinyl acetate are preferable, and ethylene is particularly preferable.

As the fluorine-containing resin (A), the following fluorine-containing resin (A1) or fluorine-containing resin (A2) is preferable.
Fluorine-containing resin (A1): Unit (a) based on TFE and / or CTFE, unit (b) based on a monomer having a carboxy group or a cyclic hydrocarbon monomer, and fluorine-containing monomer (excluding TFE and CTFE). ) Based units (c1).
Fluororesin (A2): unit (a) based on TFE and / or CTFE, unit (b) based on a monomer having a carboxy group or a cyclic hydrocarbon monomer, and a non-fluorinated monomer (however, a monomer having a carboxy group) And a unit (c2) based on (excluding cyclic hydrocarbon monomers).

The fluororesin (A1) may further have units other than the unit (a), the unit (b), and the unit (c1). Examples of the other unit include a unit (c2) based on a non-fluorinated monomer (excluding a monomer having a carboxy group and a cyclic hydrocarbon monomer).
As the fluorine-containing resin (A1), PFA having at least a unit based on TFE as the unit (a) and at least a unit based on CF ₂ = CFOR ^f1 as the fluorine-containing monomer (c1) is particularly preferable.

  Preferable specific examples of the fluorine-containing resin (A1) include TFE / PPVE / NAH copolymer, TFE / PPVE / IAH copolymer, TFE / PPVE / CAH copolymer, TFE / HFP / NAH copolymer, and TFE. / HFP / IAH copolymer, TFE / HFP / CAH copolymer, TFE / VdF / IAH copolymer, TFE / VdF / CAH copolymer, TFE / PPVE / HFP / NAH copolymer and the like.

The fluororesin (A2) may further have units other than the unit (a), the unit (b), and the unit (c2). Examples of the other unit include a unit (c1) based on a fluorine-containing monomer (excluding TFE and CTFE).
As the fluorine-containing resin (A2), ETFE having at least a unit based on TFE as the unit (a) and at least a unit based on ethylene as the non-fluorinated monomer (c2) is particularly preferable.

Preferable specific examples of the fluororesin (A2) include TFE / CH ₂ ═CH (CF ₂ ) ₄ F / NAH / ethylene copolymer, TFE / CH ₂ ═CH (CF ₂ ) ₄ F / IAH / ethylene copolymer. _{polymer, TFE / CH 2 = CH (} CF 2) 4 F / CAH / ethylene _{copolymer, TFE / CH 2 = CH (} CF 2) 2 F / NAH / ethylene copolymer, TFE _/ CH 2 = CH ( CF ₂ ) ₂ F / IAH / ethylene copolymer, TFE / CH ₂ ═CH (CF ₂ ) ₂ F / CAH / ethylene copolymer, CTFE / CH ₂ ═CH (CF ₂ ) ₄ F / NAH / ethylene copolymer _{polymer, CTFE / CH 2 = CH (} CF 2) 4 F / IAH / ethylene _{copolymer, CTFE / CH 2 = CH (} CF 2) 4 F / CAH / ethylene copolymer, CTFE / _CH 2 = _{H (CF 2) 2 F /} NAH / ethylene _{copolymer, CTFE / CH 2 = CH (} CF 2) 2 F / IAH / ethylene _{copolymer, CTFE / CH 2 = CH (} CF 2) 2 F / CAH / An ethylene copolymer etc. are mentioned.

The fluororesin (A) contains the unit (a), the unit (b), and the unit (c), and the unit (a) relative to the total molar amount of the unit (a), the unit (b), and the unit (c) ( The proportion of b) is preferably from 0.01 to 5 mol%, more preferably from 0.1 to 3 mol%, particularly preferably from 0.1 to 2 mol%.
When the content of the unit (b) is within the above range, the amount of the functional group (I) of the fluororesin (A) becomes an appropriate amount, and the crosslinkability is more excellent.

In addition, when fluororesin (A) consists of unit (a), unit (b), and unit (c), content of unit (b) is unit (a), unit (b), and unit (c 0.001 mol% with respect to the total molar amount of the fluorine-containing resin (A), the content of the functional group (I) in the fluorine-containing resin (A) is 1 × 10 ⁶ main chain carbon atoms of the fluorine-containing resin (A). This corresponds to 10 pieces per piece. The content of the unit (b) is 6 mol% with respect to the total molar amount of the unit (a), the unit (b), and the unit (c), which is the functional group (I) in the fluororesin (A). ) Content is 60,000 per 1 × 10 ⁶ main chain carbon atoms of the fluororesin (A).

In the fluororesin (A1), the unit (a) is 50 to 99.89 mol% with respect to the total molar amount of the unit (a), the unit (b), and the unit (c1), and the unit (b) It is preferable that the unit (c1) is 0.1 to 49.99 mol%, 0.01 to 5 mol%, the unit (a) is 50 to 99.4 mol%, and the unit (b) is 0.00. It is more preferable that the unit (c1) is 0.5 to 49.9 mol% at 1 to 3 mol%, the unit (a) is 50 to 98.9 mol%, and the unit (b) is 0.1 It is particularly preferable that the unit (c1) is 1 to 49.9 mol% at ˜2 mol%.
When the content of each unit is within the above range, the moldability and heat resistance are more excellent.
In particular, when the content of the unit (b) is within the above range, the functional group (I) of the fluororesin (A) becomes an appropriate amount, and the crosslinkability is more excellent.
Moreover, a moldability and heat resistance are more excellent in content of the unit (c1) in the said range.

  When the fluororesin (A1) has the unit (c2), the content of the unit (c2) is determined when the total molar amount of the unit (a), the unit (b), and the unit (c1) is 100 mol. 5 to 90 mol is preferable, 5 to 80 mol is more preferable, and 10 to 65 mol is particularly preferable.

  When the total molar amount of all the units of the fluororesin (A1) is 100 mol%, the total molar amount of the unit (a), the unit (b) and the unit (c1) is preferably 60 mol% or more, 65 mol % Or more is more preferable, and 68 mol% or more is especially preferable. A preferable upper limit is 100 mol%.

In the fluororesin (A2), the unit (a) is 30 to 70 mol% with respect to the total molar amount of the unit (a), the unit (b), and the unit (c2), and the unit (b) is 0.00. 3 to 4.0 mol%, preferably unit (c2) is 70 to 30 mol%, unit (a) is 40 to 60 mol%, and unit (b) is 0.5 to 3.5 mol% It is more preferable that the unit (c2) is 40 to 60 mol%, the unit (a) is 50 to 60 mol%, the unit (b) is 0.5 to 2.5 mol%, and the unit ( It is particularly preferable that c2) is 40 to 50 mol%.
When the content of each unit is within the above range, the fluororesin (A2) is excellent in heat resistance and chemical resistance, and the fluororesin composition containing this is excellent in elastic modulus at high temperature.
In particular, when the content of the unit (b) is within the above range, the amount of the functional group (I) of the fluororesin (A) becomes an appropriate amount, and the crosslinkability is more excellent.
When the content of the unit (c2) is within the above range, the moldability is more excellent.

  When the fluororesin (A2) has the unit (c1), the content of the unit (c1) is determined when the total molar amount of the unit (a), the unit (b), and the unit (c2) is 100 mol. 0.3 to 4.0 mol is preferable, 0.5 to 3.5 mol is more preferable, and 0.7 to 3.0 mol is particularly preferable.

  When the total molar amount of all the units of the fluororesin (A2) is 100 mol%, the total molar amount of the unit (a), the unit (b) and the unit (c2) is preferably 96 mol% or more, 97 mol % Or more is more preferable, and 98 mol% or more is particularly preferable. A preferable upper limit is 100 mol%.

  The content of the unit can be calculated by melting NMR analysis, fluorine atom content analysis, infrared absorption spectrum analysis, or the like of the fluororesin (A).

The melting point of the fluororesin (A) is preferably 200 to 320 ° C.
When the fluororesin (A) is the fluororesin (A1), the melting point thereof is preferably 260 to 320 ° C, more preferably 265 to 320 ° C, and particularly preferably 280 to 315 ° C. When the melting point of the fluororesin (A1) is not less than the lower limit of the above range, the heat resistance is excellent, and when it is not more than the upper limit of the above range, the moldability is excellent.
When the fluororesin (A) is the fluororesin (A2), the melting point is preferably 200 to 280 ° C, particularly preferably 200 to 260 ° C. When the melting point of the fluororesin (A2) is not less than the lower limit of the above range, the heat resistance is more excellent, and when it is not more than the upper limit of the above range, the moldability is excellent.
The melting point of the fluororesin (A) can be adjusted by the type and content ratio of the units constituting the fluororesin (A), the molecular weight, and the like. For example, the melting point tends to increase as the proportion of the unit (a) described later increases.

The fluororesin (A) can be melt-molded. “Melting is possible” means exhibiting melt fluidity.
In a preferred embodiment of the present invention, the melt flow rate (Melt flow rate (Melt) measured under a load of 49 N at a temperature 20 ° C. or higher than the melting point of the fluororesin (A) of the fluororesin (A). Flow Rate): hereinafter referred to as “MFR”) is preferably 0.1 to 1,000 g / 10 minutes, more preferably 0.5 to 100 g / 10 minutes, still more preferably 1 to 30 g / 10 minutes, 5 to 25 g / 10 min is particularly preferable, and 5 to 20 g / 10 min is most preferable. When the MFR is not less than the lower limit of the above range, the moldability of the fluororesin (A) and the molded body formed from the fluororesin (A) are excellent in surface smoothness and appearance, The molded object containing this fluororesin (A) is more excellent in mechanical strength as it is below an upper limit.

  In another preferred embodiment of the present invention, the MFR measured under a load of 49 N at a temperature 20 ° C. or higher than the melting point of the fluororesin (A) of the fluororesin (A) is 0.5 to 30 g / 10 min is preferable, 1 to 25 g / 10 min is more preferable, 5 to 20 g / 10 min is further preferable, 5 to 15 g / 10 min is particularly preferable, and 5 to 13 g / 10 min is most preferable. When the MFR is not more than the above upper limit value, the mechanical strength is excellent, and when it is not less than the above lower limit value, the moldability is excellent.

For example, when the fluororesin (A) is a fluororesin (A1), the measurement temperature of the MFR is usually 372 ° C. When the fluororesin (A) is the fluororesin (A2), 297 ° C. is usually adopted.
MFR is a measure of the molecular weight of the fluororesin (A). When the MFR is large, the molecular weight is low, and when the MFR is small, the molecular weight is large. The molecular weight of the fluororesin (A), and thus the MFR, can be adjusted by the production conditions of the fluororesin (A). For example, if the polymerization time is shortened during polymerization of the monomer, the MFR tends to increase. Moreover, when the fluororesin (A) obtained by the polymerization reaction is heat-treated, a crosslinked structure is formed, and the molecular weight tends to increase and the MFR tends to decrease.

The fluorine-containing resin (A) can be produced by a conventional method. For example,
(1) A method of using a monomer having a functional group (I) when producing a fluororesin (A) by a polymerization reaction,
(2) A method for producing a fluororesin (A) by a polymerization reaction using a radical polymerization initiator having a functional group (I) or a chain transfer agent,
(3) A fluorine-containing resin having a functional group (I) is formed by heating a fluorine-containing resin having no functional group (I) and partially thermally decomposing the fluorine-containing resin to generate a carboxy group. A) to obtain
(4) A method in which a monomer having a functional group (I) is graft-polymerized to a fluorine-containing resin having no functional group (I), and the functional group (I) is introduced into the fluorine-containing resin.
As a method for producing the fluororesin (A), the method (1) is preferred.

When the fluororesin (A) is produced by a polymerization reaction, the polymerization method is not particularly limited, but for example, a polymerization method using a radical polymerization initiator is preferable.
Examples of the polymerization method include bulk polymerization, solution polymerization using an organic solvent such as fluorinated hydrocarbon, chlorinated hydrocarbon, fluorinated chlorohydrocarbon, alcohol, hydrocarbon, an aqueous medium and an appropriate organic solvent as necessary. And suspension polymerization using an aqueous medium, and emulsion polymerization using an aqueous medium and an emulsifier. Among these, solution polymerization is preferable.

As the radical polymerization initiator, an initiator whose half-life is 10 hours is preferably 0 to 100 ° C., and an initiator whose temperature is 20 to 90 ° C. is particularly preferable.
Specific examples include azo compounds such as azobisisobutyronitrile, non-fluorine diacyl peroxides such as isobutyryl peroxide, octanoyl peroxide, benzoyl peroxide and lauroyl peroxide, peroxydicarbonates such as diisopropylperoxydicarbonate, tert - butyl peroxypivalate, tert- butylperoxy isobutyrate, tert- butyl peroxy ester peroxy acetate, _{etc., 2} (where _{(Z (CF 2) r COO} ), Z represents a hydrogen atom, a fluorine atom or a chlorine atom , R is an integer of 1 to 10.) Fluorine-containing diacyl peroxide such as a compound represented by formula (I), inorganic peroxides such as potassium persulfate, sodium persulfate, and ammonium persulfate.

  A chain transfer agent may be used at the time of polymerization, and alcohols such as methanol and ethanol, 1,3-dichloro-1,1,2,2,3-pentafluoropropane, 1,1-dichloro-1-fluoroethane And chlorofluorohydrocarbons such as pentane, hexane, and cyclohexane.

As at least one of the radical polymerization initiator and the chain transfer agent, as described above, a compound having the functional group (I) may be used. Thereby, functional group (I) can be introduce | transduced into the principal chain terminal of the fluororesin (A) manufactured.
Examples of such radical polymerization initiators include di-n-propyl peroxydicarbonate, diisopropyl peroxycarbonate, t-butyl peroxyisopropyl carbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, di-2-ethylhexyl peroxydi. Examples of the chain transfer agent include acetic acid, acetic anhydride, methyl acetate, ethylene glycol, and propylene glycol.

When the fluororesin (A) having the unit (b) is polymerized, the concentration during polymerization of the monomer having a carboxy group and the cyclic hydrocarbon monomer is preferably 0.01 to 5 mol% based on the total monomers, and 0 0.1-3 mol% is more preferable, and 0.1-2 mol% is especially preferable. When the concentration of the monomer is in the above range, the polymerization rate during production is moderate, and when the concentration of the monomer is too high, the polymerization rate tends to decrease.
During the polymerization, as the monomer having a carboxy group and the cyclic hydrocarbon monomer are consumed in the polymerization, the consumed amount is continuously or intermittently supplied into the polymerization tank, and the monomer having the carboxy group and the cyclic hydrocarbon monomer It is preferable to maintain the concentration of in the above range.

(Compound for forming a crosslinked structure (B))
The compound for forming a crosslinked structure (B) comprises two or more carboxylic acid ions selected from an acid anhydride group and a carboxy group derived from a carboxy group, and a divalent or higher valent metal ion. Is a compound for forming a crosslinked structure formed by ion bonding.
Specifically, the compound for forming a crosslinked structure (B) is any one of the compounds represented by the following (B1) to (B3).
(B1) a compound containing a divalent or higher valent metal ion source capable of ionic bonding with two or more carboxylate ions and capable of opening an acid anhydride group (in this specification, simply referred to as “compound (B1)”) Say.).
(B2) A compound containing a divalent or higher-valent metal ion source capable of ion-bonding with two or more carboxylate ions (excluding the compound (B1)) (in this specification, simply “compound (B2)” Say.).
(B3) A compound capable of ring-opening an acid anhydride group (excluding the compound (B1)) (herein also simply referred to as “compound (B3)”).
Which of the compounds (B1) to (B3) is included in the fluorine-containing resin composition as the crosslinking structure-forming compound (B) depends on the acid anhydride group of the fluorine-containing resin (A). It is determined depending on which of the ion and the carboxylate ion derived from the carboxy group is to be crosslinked.

  In the method for producing a crosslinked fluororesin described later, when the fluororesin composition is heated to a melting point or higher, the functional group (I) of the fluororesin (A) and the compound for forming a crosslinked structure (B) act. Thus, a crosslinked structure is formed. Specifically, from the acid anhydride group of the fluororesin (A), a carboxy group is first generated by the catalytic action of a compound capable of ring opening of the acid anhydride group in the crosslinked structure forming compound (B). Then, the carboxy group reacts with a compound containing a divalent or higher metal ion source in the crosslinked structure forming compound (B) to form a crosslinked structure. On the other hand, from the carboxy group contained in the fluororesin (A), the carboxy group reacts with a compound containing a divalent or higher valent metal ion source in the crosslinked structure forming compound (B) without requiring the catalytic action. As a result, a crosslinked structure is formed.

For example, when a carboxylate ion derived from an acid anhydride group is cross-linked, the compound (B) for forming a cross-linked structure includes the compound (B1), the compound (B1) and the compound (B2), the compound (B2) and the compound (B3). Or a compound (B1), a compound (B2), and a compound (B3).
When the carboxylate ion derived from the carboxy group is crosslinked, the crosslinked structure forming compound (B) is the compound (B1), the compound (B2), or the compound (B1) and the compound (B2).
In addition, from the point that a fluorine-containing crosslinked product can be efficiently obtained, when the carboxylate ion is derived from an acid anhydride group, the compound for forming a crosslinked structure (B) is compound (B1), compound (B1) and compound. (B2), or compound (B2) and compound (B3) are preferred. When the carboxylate ion is derived from a carboxy group, the compound (B) for forming a crosslinked structure is preferably the compound (B1) or the compound (B2).
Here, as a carboxylate ion, when a carboxylate ion derived from both an acid anhydride group and a carboxylate ion derived from both carboxy groups coexist, the compound (B) for forming a crosslinked structure is compound (B1). Compound (B1) and Compound (B2), Compound (B2) and Compound (B3), or Compound (B1), Compound (B2) and Compound (B3) are preferable, and Compound (B1) and Compound (B3) are preferred. Particularly preferred are B1) and compound (B2), or compound (B2) and compound (B3).
Specific examples of compounds (B1) to (B3) are shown below.

<Compound (B1)>
Examples of the compound (B1) include magnesium acetate tetrahydrate, zinc acetate dihydrate, magnesium stearate, calcium stearate, zinc stearate and other organic acids and divalent or higher metal salts, calcium carbonate, magnesium carbonate And salts of carbonic acid such as divalent or higher metals.
Among these, a compound having a small particle size or a compound having a melting point lower than the kneading temperature of the fluororesin composition is preferable from the viewpoint of excellent crosslinking reactivity. As a specific preferred example, acetate and stearate are preferable because the melting point is lower than the kneading temperature of the fluororesin composition.

<Compound (B2)>
Examples of the compound (B2) include metal oxides such as zinc oxide, magnesium oxide, calcium oxide, aluminum oxide, copper oxide, iron oxide, and lead oxide.
Among these, a compound having a small particle size or a compound having a melting point lower than the kneading temperature of the fluororesin composition is preferable from the viewpoint of excellent crosslinking reactivity.

<Compound (B3)>
As the compound (B3), a salt of an organic acid such as sodium stearate and a monovalent metal, a salt of carbonic acid and a monovalent metal such as sodium hydrogencarbonate, an organic salt such as tetraphenylphosphonium bromide, N, N , N ′, N′-tetramethyl-1,3-diaminopropane, amines such as tetramethylethylenediamine, and the like.
Among these, from the viewpoint of excellent crosslinking reactivity, a compound having a small particle size or a compound having excellent thermal stability at the kneading temperature of the fluorine-containing resin composition is preferable. As a specific preferred example, a salt of an organic acid and a monovalent metal, or an organic salt such as tetraphenylphosphonium bromide is preferable because of excellent thermal stability at the kneading temperature.

The compounds (B1) to (B3) include hydrates as long as they can form hydrates.
When the crosslinking structure forming compound (B) crosslinks a carboxylic acid ion derived from the acid anhydride group of the fluorinated resin (A), the carboxylic acid ion derived from the carboxy group of the fluorinated resin (A) Only the compounds required in each case of crosslinking may be used, or compounds (B1) to (B3) other than the required compounds may be used in combination.

When the carboxylate ion derived from the acid anhydride group of the fluororesin (A) is cross-linked, the cross-linking structure-forming compound (B) is selected from magnesium acetate, magnesium stearate, At least one organic acid metal salt selected from the group consisting of zinc stearate, calcium stearate, and zinc acetate, or a combination of the organic acid metal salt and one or both of magnesium oxide and zinc oxide Is particularly preferred.
When the carboxylate ion derived from the carboxy group of the fluororesin (A) is crosslinked, the crosslinked structure-forming compound (B) has a low creep displacement of the molded product, so that magnesium acetate, magnesium stearate, stearic acid is used. A combination of at least one organic acid metal salt selected from the group consisting of zinc, calcium stearate and zinc acetate, and one or both of metal oxides of magnesium oxide and zinc oxide is preferred.

In the fluorine-containing resin composition, the molar concentration of the acid anhydride group and carboxy group of the fluorine-containing resin (A) and the molar concentration of the metal of the crosslinking structure forming compound (B) satisfy the following formula (1). It is preferable.
0.01 ≦ (Z × n) / (X + 2Y) ≦ 1,000 (1)
[In Formula (1), Z is the molar concentration (mol / g) of the metal which the said compound for bridge | crosslinking structure formation (B) contained in the said fluororesin composition has, n is the said metal and said metal ion. X is the molar concentration (mol / g) of the carboxy group of the fluororesin (A) contained in the fluororesin composition, and Y is the fluororesin composition. It is the molar concentration (mol / g) of the acid anhydride group of the fluororesin (A) contained in the product. ]
If the molar concentration of the acid anhydride group and carboxy group of the fluororesin (A) and the molar concentration of the metal of the compound (B) for forming a crosslinked structure satisfy the formula (1), the crosslinking reactivity is excellent.
“(Z × n) / (X + 2Y)” in Formula (1) is more preferably 0.1 or more and 100 or less, further preferably 0.1 or more and 50 or less, and particularly preferably 0.1 or more and 30 or less. If it is this range, it is excellent by crosslinking reactivity.

(Other resins)
The fluorine-containing resin composition may contain other resins than the fluorine-containing resin (A) as necessary, as long as the effects of the present invention are not impaired.
Other resins are preferably fluorine-containing resins (excluding the fluorine-containing resin (A)) because they have a low dielectric constant and dielectric loss tangent and are excellent in electrical characteristics.
Examples of the fluorine-containing resin as another resin (hereinafter also referred to as “fluorine-containing resin (B)”) include the unit (a) and the unit (c), and the unit (b). And a copolymer containing no.

  Specific examples of the fluororesin (B) include those having no functional group (I) among ETFE, PFA, FEP, PCTFE, ECTFE, PVdF, and the like.

  When the fluorine-containing resin composition contains the fluorine-containing resin (B), the content of the fluorine-containing resin (B) in the fluorine-containing resin composition is the same as that of the fluorine-containing resin (A) and the fluorine-containing resin (B). 10-90 mass% is preferable with respect to a total amount (100 mass%). When the content of the fluorine-containing resin (B) is not less than the lower limit of the above range, the heat resistance is further improved, and when it is not more than the upper limit of the above range, a sufficient amount of the resin contributing to the crosslinking reaction is present in the whole. This does not impair the crosslinking reactivity of the fluororesin (A).

(Additive)
The fluorine-containing resin composition can be used in a range that does not impair the effects of the present invention, if necessary, and includes pigments, ultraviolet absorbers, light stabilizers, surface conditioners, pigment dispersants, flame retardants, plasticizers, fillers, and thickeners. You may contain additives, such as an agent, adhesion improving agent, and a matting agent.

(Usage)
The fluorine-containing resin composition may be dissolved or dispersed in a liquid medium and used as a coating liquid. The coating liquid can be used by applying it to a substrate or the like by wet coating, for example.
Examples of the liquid medium include fluorine-containing aromatic compounds described in paragraphs [0035] to [0062] of WO2010 / 044421 and paragraphs [0037] to [0038] of WO2010 / 044445; Examples thereof include chain hydrocarbon compounds having a carbonyl group described in paragraphs [0042] to [0048] of 2010/044445.

[Method for producing crosslinked fluoropolymer]
The method for producing a cross-linked fluororesin of the present invention has a cross-linked structure in which a carboxylic acid ion derived from one or both of an acid anhydride group and a carboxy group and a divalent or higher metal ion are ionically bonded. It is a manufacturing method of the fluororesin crosslinked body which has.

  The production method comprises heating a fluorine-containing resin composition containing the fluorine-containing resin (A) having a functional group (I) and the crosslinking structure-forming compound (B) to a temperature equal to or higher than the melting point of the fluorine-containing resin (A). Thus, the crosslinked structure is formed. However, preferred types and combinations of the cross-linking structure forming compound (B) are as described above.

The timing for heating to the melting point or higher is not particularly limited, and may be during the time until the molded body is obtained or when the molded body is obtained. Examples of the method of heating to the melting point or higher until a molded body is obtained include melt kneading and firing.
As a specific method, when the fluorine-containing resin composition is melt-kneaded, a method of heating to a melting point or higher, and when the fluorine-containing resin composition is in a powder state, the powder (the powder of the fluorine-containing resin (A)) And the powder of the compound for forming a crosslinked structure (B) as an essential component and, if necessary, including other resin powder and additive powder) on the base material, the melting point or higher is exceeded during firing. Method of heating, when using a coating liquid in which the fluorine-containing resin composition is dissolved or dispersed in a liquid medium, the fluorine-containing resin obtained by wet-coating the coating liquid on a substrate and then removing the liquid medium by heating or the like Examples include a method of heating to the melting point or higher when firing the composition. Among these, from the viewpoint of excellent reactivity, a method of heating to the melting point or higher is preferred during the melt-kneading of the fluorine-containing resin composition.

A heating temperature will not be specifically limited if it is more than melting | fusing point of the fluorine-containing resin (A) to be used. The heating temperature is preferably (melting point of fluorine-containing resin (A) + 5 ° C.) to (melting point of fluorine-containing resin (A) + 100 ° C.), and (melting point of fluorine-containing resin (A) + 10 ° C.) to (fluorine-containing resin ( A melting point of A) + 80 ° C. is more preferable, and (melting point of fluororesin (A) + 20 ° C.) to (melting point of fluororesin (A) + 70 ° C.) is particularly preferable.
If the heating temperature is at least the lower limit, the fluororesin (A) and the crosslinked structure-forming compound (B) are likely to undergo a crosslinking reaction, whereas if the heating temperature is not more than the upper limit, the fluororesin (A) Reduction in mechanical strength due to thermal decomposition and foaming during molding due to decomposition products can be suppressed.

[Molded body]
The molded article of the present invention can be obtained by melt-molding the fluororesin crosslinked product obtained by the above-described method for producing a crosslinked fluororesin into a shape for each application.
The usage of the molded body is not particularly limited. Especially, it is preferable to use for semiconductor devices, such as an electric wire, such as an aircraft electric wire and an automobile electric wire, and a solar cell, which require heat resistance and mechanical strength at high temperature. When using for an electric wire, it is preferable that a molded object is used for the coating material for electric wires.

(Production method)
The molded body may be manufactured by a known molding method. Moreover, you may perform continuously with the manufacturing method of the above-mentioned fluororesin crosslinked body. The molding method is not particularly limited, and examples thereof include extrusion molding, mold molding, inflation molding, and injection molding.
Specifically, first, according to the above-mentioned method for producing a fluororesin cross-linked product, the fluororesin composition is heated to a melting point or higher during melting and kneading to produce a fluororesin cross-linked pellet, The method of manufacturing a molded object by performing shaping | molding using is mentioned. In this method, after the production of the pellet, the molded body may be continuously produced, and the pellet is stored until the production of the molded body is started, and the stored pellet is used as necessary. You may manufacture a molded object.

Examples of the method for continuously producing a molded body include a method using an extruder to which a die or the like is connected. Specifically, while the fluororesin composition is melt-kneaded while being heated to the melting point or higher in the extruder to produce a fluororesin crosslinked body, the fluororesin crosslinked body is sent to a die or the like. Etc., it is projected in the form of a film or tube and cooled, and a molded body is produced.
For example, as a manufacturing method when the molded body is a coating material for electric wires, a pellet of the fluororesin crosslinked body obtained by the above-described method from the above-mentioned fluororesin composition is melted, and the core wire is discharged from the discharge port of the die. A method of forming a coating layer around the core wire by extruding around the core wire can be mentioned.
As a material of the core wire, copper is preferable. The core wire may be plated with tin, silver or the like.
Examples of the apparatus used for the production of the electric wire include an extruder provided with an electric wire die cross head.
The diameter of the core wire is preferably 10 μm to 3 mm. The thickness of the coating layer is preferably 5 μm to 2 mm. The diameter of the electric wire is preferably 20 μm to 5 mm.

The molding temperature is preferably (melting point of fluorine-containing resin (A) + 5 ° C.) to (melting point of fluorine-containing resin (A) + 100 ° C.), and (melting point of fluorine-containing resin (A) + 10 ° C.) to (fluorine-containing resin ( A melting point of A) + 80 ° C. is more preferable, and (melting point of fluororesin (A) + 20 ° C.) to (melting point of fluororesin (A) + 70 ° C.) is particularly preferable.
The molding time is preferably 0.1 to 30 minutes, more preferably 1 to 20 minutes, and particularly preferably 1 to 10 minutes. When the amount is not less than the lower limit of the range, it can be sufficiently crosslinked, and when it is not more than the upper limit of the range, the fluororesin crosslinked product is hardly decomposed.

[Function and effect]
In the present invention, when the fluororesin composition is heated to the melting point or higher, the functional group (I) of the fluororesin (A) and the crosslinking structure forming compound (B) act to form a crosslinked structure. Is done. From the acid anhydride group in the functional group (I), first, a carboxy group is generated by the catalytic action of a compound capable of opening the acid anhydride group in the compound for forming a crosslinked structure (B). A group reacts with a compound containing a metal ion source in the compound for forming a crosslinked structure (B), whereby a crosslinked structure is formed. From the carboxy group in the functional group (I), the cross-linked structure is formed by reacting the carboxy group with a compound containing a metal ion source in the cross-linking structure forming compound (B) without requiring the catalytic action. It is formed.
Therefore, according to the present invention, the cross-linking treatment can be easily performed by such a mechanism, the creep displacement of the molded body is small, and the mechanical strength is high.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples. In Examples 1 to 12 which will be described later, Examples 3, 5 to 8 and 10 to 12 are examples, and Examples 1, 2, 4 and 9 are comparative examples.

[material]
Fluorine-containing resin (A2-1): acid anhydride group-containing ETFE produced in Production Example 1 described later. Units based on TFE / CH ₂ = CH (CF ₂ ) ₂ F units / units based on IAH / units based on ethylene = 93.5 / 5.7 / 0.8 / 62.9 (molar ratio), MFR : 23 g / 10 minutes, Melting point: 230 ° C., IAH-derived carbonyl group content: 9.8 × 10 ³ with respect to 1 × 10 ⁶ main chain carbon atoms of the fluororesin.
Fluorine-containing resin (A1-1): An acid anhydride group-containing PFA produced in Production Example 2 described later. Unit based on TFE / unit based on NAH / unit based on PPVE = 97.9 / 0.1 / 2.0 (molar ratio), MFR 17.6 g / 10 min, melting point: 300 ° C., carbonyl group content derived from NAH : 2.0 × 10 ³ for 1 × 10 ⁶ main chain carbon atoms of the fluororesin.
Compound (B1-1): Magnesium acetate tetrahydrate (Wako Pure Chemical Industries, Ltd.)
Compound (B1-2): Magnesium stearate (manufactured by Wako Pure Chemical Industries, Ltd.)
Compound (B1-3): Zinc acetate dihydrate (manufactured by Junsei Co., Ltd.)
Compound (B2-1): Zinc oxide (manufactured by Sakai Chemical Industry, trade name: FINEX30)
Compound (B2-2): Magnesium oxide (manufactured by Sakai Chemical Co., Ltd., trade name: 500A)
Compound (B3-1): Sodium stearate (Wako Pure Chemical Industries, Ltd.)

[Evaluation method]
(Evaluation of fluororesin (A))
<Copolymerization composition>
The copolymer composition was calculated by melt NMR analysis, fluorine atom content analysis and infrared absorption spectrum analysis.

<Content of functional group (I) in fluororesin>
First, the ratio of the unit based on the monomer (IAH or NAH) having the functional group (I) in the fluororesin was determined by the following infrared absorption spectrum analysis.
A fluorine-containing resin was press-molded to obtain a film having a thickness of 200 μm. In the infrared absorption spectrum, the absorption peak in the unit based on IAH and NAH in the fluororesin appears at 1,778 cm ⁻¹ . The absorbance of the absorption peak was measured, and the content M (mol%) of the unit based on IAH or NAH was determined using the relational expression of M = aL. Here, L is the absorbance at 1,778 cm ⁻¹ and a is a coefficient. As a, a = 0.87 determined using IAH as a model compound was used.
Then the M (mol%), the number of the fluorine-containing resin in the main chain number 1 × 10 ⁶ cells for functional group carbon (I) (acid anhydride group) is calculated [M × ¹⁰ 6/100] Pieces and .
The number of main chain carbon atoms 1 × 10 ⁶ cells for functional group (I) (acid anhydride group) derived from the carbonyl group of the fluorine-containing resin is calculated as ^{[2 × M × 10 6/} 100] Pieces .

<MFR of fluorine-containing resin (g / 10 min)>
Using a Techno Seven melt indexer, the mass (g) of the fluororesin (A) flowing out from a nozzle having a diameter of 2 mm and a length of 8 mm for 10 minutes (unit time) was measured under the following conditions. Was MFR (g / 10 min).
Fluorine-containing resin (A2-1): Measured at a load of 49 N and 297 ° C. according to ASTM D3159.
Fluorine-containing resin (A1-1): Measured at a load of 49 N and 372 ° C. in accordance with ASTM D3307.

<Melting point (° C)>
Using a differential scanning calorimeter (DSC device) manufactured by Seiko Electronics Co., Ltd., record the melting peak when the temperature of the fluororesin (A) is increased at a rate of 10 ° C./min, and the temperature corresponding to the maximum value (° C.) Was the melting point.

(Evaluation of crosslinked fluoropolymer)
Dynamic viscoelasticity measurement and viscosity measurement were performed using pellets of a cross-linked fluororesin. The tensile test, IR measurement, and creep test were performed using a molded body (fluorine-containing resin crosslinked film having a thickness of 100 μm) obtained from the pellets.

<Dynamic viscoelasticity measurement>
Dynamic viscoelasticity measurement was performed in a temperature dispersion mode using a dynamic viscoelasticity measuring device Vibron manufactured by IT Measurement Control Co., Ltd. Measurement was performed from room temperature at a heating rate of 5 ° C./min. The rigidity at high temperature was evaluated by the storage elastic modulus Er (Pa) at 10 Hz at 300 ° C. for ETFE and 330 ° C. for PFA.

<Tensile test>
In accordance with ASTM D1822-L, a dumbbell was punched from the molded body using a super dumbbell cutter (SDMK-100L manufactured by Dumbbell Co., Ltd.) to obtain a test piece. A tensile test was conducted at a speed of 10 mm / min with a Tensilon universal testing machine (manufactured by A & D), and the maximum point stress (MPa) at N number (number of samples) = 3 was determined.

<IR measurement>
The acid anhydride group reaction rate was calculated by IR analysis as follows.
Using the molded body, infrared absorption spectrum analysis (IR analysis) was performed. In any case, the absorbance of the peak appearing at 1,870 cm ⁻¹ (corresponding to the absorption peak of C═O stretching vibration in a unit based on IAH (itaconic anhydride)) was measured, and the absorbance was observed at 2,200 cm ⁻¹ . The reduction rate of the acid anhydride relative to the fluorine-containing resin not added with the crosslinking structure-forming compound (B) was calculated by normalizing with the absorption peak of the obtained CF overtone. The reduction rate was defined as the acid anhydride group reaction rate (%).
Moreover, the presence or absence of crosslinking was determined by whether or not a peak of a carboxylic acid metal salt in the vicinity of 1,650 cm ^{−1 appeared} .

<Viscosity measurement>
The pellet of the fluororesin crosslinked product is pre-heated at a predetermined temperature for 10 minutes using a capillograph (CAPIROGRAPH 1C manufactured by Toyo Seiki Seisakusho), and L (capillary length) at a speed of 10 mm / min (shear rate 15.2 s ⁻¹ ). And the viscosity was measured by extruding from a die hole of D (diameter) 2 mm. Viscosity value (Pa · s) was obtained with N number (number of samples) = 3. Measurements were performed at 300 ° C. for ETFE and 330 ° C. for PFA. A higher viscosity value indicates a higher viscosity.

<Creep test>
In accordance with ASTM D1822-L, a dumbbell was punched from the molded body using a super dumbbell cutter (SDMK-100L manufactured by Dumbbell Co., Ltd.) to obtain a test piece. When Tensilon Universal Testing Machine (manufactured by A & D Co., Ltd.) was applied and held for 20 minutes with a stress of 30 MPa applied to the test piece for Examples 1 to 8 and a stress of 20 MPa applied to the test piece for Examples 9 to 12 The displacement of was evaluated. The moving speed of the stress adjustment was set to 5 mm / min, and the measurement was performed at room temperature. The creep displacement (%) was calculated by averaging the test results with N number (number of samples) = 3. The smaller the creep displacement, the better the creep resistance.

[Production Example 1: Production of fluorinated resin (A2-1) (acid anhydride group-containing ETFE)]
A polymerization tank equipped with a stirrer with an internal volume of 94 L was degassed, 71.3 kg of 1-hydrotridecafluorohexane, 1,3-dichloro-1,1,2,2,3-pentafluoropropane (Asahi Glass Co., Ltd.) AK225cb, hereinafter referred to as “AK225cb”), 20.4 kg of CH ₂ ═CH (CF ₂ ) ₂ F, and 4.45 g of IAH were charged, and the temperature inside the polymerization tank was raised to 66 ° C. The pressure was increased to 1.5 MPa / G with a gas having a molar ratio of 89/11. As a polymerization initiator, 1 L of a 0.7% 1-hydrotridecafluorohexane solution of tert-butylperoxypivalate was charged to initiate polymerization. A monomer mixture gas of ETFE in a 59.5 / 40.5 molar ratio was continuously charged so that the pressure was constant during the polymerization. Also, CH ₂ ═CH (CF ₂ ) ₂ F in an amount corresponding to 3.3 mol% and IAH in an amount corresponding to 0.8 mol% are continuously added to the total number of moles of TFE and ethylene charged during the polymerization. I was charged. 9.9 hours after the start of the polymerization, when 7.28 kg of the monomer mixed gas was charged, the temperature in the polymerization tank was lowered to room temperature and purged to normal pressure to obtain a slurry-like fluorine-containing copolymer 1.

  The obtained slurry-like fluorine-containing copolymer 1 was put into a 200 L granulation tank charged with 77 kg of water, heated to 105 ° C. with stirring and granulated while distilling and removing the solvent. Grains were obtained. The obtained granulated product was dried at 150 ° C. for 15 hours to obtain 6.9 kg of a fluororesin (A2-1).

[Production Example 2: Production of fluororesin (A1-1) (acid anhydride group-containing PFA)]
After the inside of the polymerization tank equipped with a stirrer having an internal volume of 430 L was deaerated, 369 kg of AK225cb and 30 kg of PPVE as a fluorine monomer were charged into the polymerization tank. Next, the temperature in the polymerization tank was raised to 50 ° C., and after further charging 50 kg of TFE, the pressure in the polymerization tank was increased to 0.89 MPa / G. Next, a polymerization initiator solution in which (perfluorobutyryl) peroxide was dissolved in AK225cb so as to be 0.36% by mass was prepared, and 3 L of the polymerization initiator solution was added to 6.25 mL per minute in the polymerization tank. Polymerization was carried out while continuously adding at a rate of. During the polymerization, TFE was continuously charged so that the pressure in the polymerization tank was maintained at 0.89 MPa / G. Further, a solution obtained by dissolving NAH, which is a cyclic hydrocarbon monomer, in AK225cb so as to be 0.3% by mass was continuously charged together with TFE charged during polymerization. The amount of NAH charged during the polymerization was maintained at 0.1 mol% with respect to the number of moles of TFE charged together during the polymerization. Eight hours after the start of polymerization, when the amount of TFE continuously charged during the polymerization reached 32 kg, the temperature in the polymerization tank was lowered to room temperature, and the pressure was purged to normal pressure. Copolymer 2 was obtained.

  The obtained slurry-like fluorine-containing copolymer 2 was solid-liquid separated from AK225cb and then dried at 150 ° C. for 15 hours to obtain 33 kg of fluorine-containing resin (A1-1).

[Examples 1 and 3-12]
(Manufacture of fluororesin crosslinked product)
The components shown in Table 1 are added to a laboratory plast mill mixer manufactured by Toyo Seiki Seisakusho, and pre-kneading is performed for 1 minute at 20 revolutions per minute (the kneading temperature during pre-kneading is the melt kneading shown in Table 1). After that, melt kneading was carried out at 50 revolutions per minute at the kneading temperature and kneading time shown in Table 1. Next, the contents were taken out from the lab plast mill mixer, allowed to stand, cooled to room temperature (20 to 25 ° C.), and cut with a cutter to obtain pellets of a cross-linked fluororesin.

(Manufacture of molded products)
Filled with fluorinated resin crosslinked pellets obtained in a SUS316 mold having a thickness of 100 μm and a 100 mm square, and set in a press machine (Mini Test Press MP-WCL manufactured by Toyo Seiki Seisakusho Co., Ltd.) set to a predetermined temperature. A 150 mm × 150 mm SUS316 mirror plate was used as a lid. After preheating for 5 minutes, compression molding was performed at a surface pressure of 8.7 MPa for 5 minutes, and cooling was performed at a surface pressure of 8.7 MPa for 5 minutes to obtain a film having a thickness of 100 μm molded in the size of the mold.

[Example 2]
Using the fluororesin (A2-1) obtained in Production Example 1 instead of the fluororesin crosslinked pellets, a film having a thickness of 100 μm was obtained in the same manner as Example 1. Next, the film was irradiated with a 24 Mrad electron beam to obtain a molded article of Example 2.
Table 1 shows the content of each component, production conditions, and evaluation results in Examples 1 to 12.

As shown in Table 1, from the results of dynamic viscoelasticity measurement and IR measurement, it was confirmed that in Examples 3, 5 to 8, and 10 to 12, the fluororesin was crosslinked with metal ions.
The molded bodies obtained in Examples 3 and 5-8 had higher maximum point stress and smaller creep displacement than the molded bodies obtained in Example 1. This is considered that mechanical strength and creep resistance were improved by crosslinking.

The molded bodies obtained in Examples 3 and 5 had a smaller creep displacement than the molded body obtained in Example 8 in which the compounding amount (mmol%) of the crosslinking structure-forming compound (B) was close. This is because Example 8 uses only Compound (B1) as Compound (B) for forming a crosslinked structure, whereas Examples 3 and 5 use Compound (B1) and Compound (B2) in combination. This is probably because of this. When only the compound (B1) is used as the cross-linking structure forming compound (B), the compound (B1) is consumed as a metal ion source, so that the catalytic action for opening the acid anhydride group by the compound (B1) is performed. Decreases. On the other hand, when the compound (B1) and the compound (B2) are used in combination as the crosslinking structure-forming compound (B), the compound (B2) is present as a metal ion source, so that the compound (B1) alone is used. The compound (B1) is hardly consumed, the catalytic action for ring opening of the acid anhydride group by the compound (B1) is difficult to decrease, and the crosslinking is likely to proceed.
The molded body obtained in Example 11 had a smaller creep displacement than the molded body obtained in Example 10. This indicates that the greater the content of the crosslinking structure-forming compound (B), the smaller the creep displacement and the higher the resistance to high temperatures.
In the molded bodies obtained in Examples 1 and 9, since the fluorine-containing resin composition did not contain the compound (B) for forming a crosslinked structure, the acid anhydride group in the fluorine-containing resin (A) did not undergo a crosslinking reaction.
In Example 4, although the fluorine-containing resin composition contains the compound (B2) but does not contain the compound (B1) and the compound (B3), the acid anhydride in the fluorine-containing resin (A) cannot be ring-opened. The acid anhydride group in the fluororesin (A) did not undergo a crosslinking reaction.

In Example 2 where the crosslinking reaction was performed by electron beam irradiation, the acid anhydride group did not undergo a crosslinking reaction.
The molded product obtained in Example 2 had a lower maximum point stress than the molded product obtained in Example 1 in which the crosslinking reaction was not performed. This indicates that the mechanical strength is reduced by the electron beam irradiation.

  Since the molded body obtained by the present invention has a small creep displacement and a high mechanical strength, it can be used for electric wires such as aircraft electric wires and automobile electric wires, and semiconductor devices such as solar cells.

Claims (11)

A method for producing a cross-linked fluororesin having a cross-linked structure in which a carboxylate ion derived from one or both of an acid anhydride group and a carboxy group and a divalent or higher-valent metal ion are ion-bonded,
A fluorine-containing resin composition containing the fluorine-containing resin (A) having either one or both of an acid anhydride group and a carboxy group and the cross-linking structure-forming compound (B) is equal to or higher than the melting point of the fluorine-containing resin (A). To form the cross-linked structure,
When the carboxylate ion is derived from an acid anhydride group, the compound for forming a crosslinked structure (B) contains the following compound (B1), the following compound (B1), the following compound (B2), the following compound (B2), and The following compound (B3), or the following compound (B1), the following compound (B2) and the following compound (B3),
When the carboxylate ion is derived from a carboxy group, the compound for forming a crosslinked structure (B) is the following compound (B1), the following compound (B2), or the following compound (B1) and the following compound (B2). A method for producing a crosslinked fluororesin, which is characterized in that it exists.
(B1) A compound containing a divalent or higher valent metal ion source capable of ion-bonding with two or more carboxylate ions and capable of opening an acid anhydride group.
(B2) A compound containing a divalent or higher valent metal ion source capable of ion-bonding with two or more carboxylate ions (excluding the compound (B1)).
(B3) A compound capable of ring opening of an acid anhydride group (excluding the compound (B1)). In the fluorine-containing resin composition, the molar concentration of the acid anhydride group and the carboxyl group that the fluorine-containing resin (A) has, and the molar concentration of the metal that the compound for forming a crosslinked structure (B) has the following formula ( The manufacturing method of the fluororesin crosslinked body of Claim 1 which satisfy | fills 1).
0.01 ≦ (Z × n) / (X + 2Y) ≦ 1,000 (1)
[In Formula (1), Z is the molar concentration (mol / g) of the metal which the said compound for bridge | crosslinking structure formation (B) contained in the said fluororesin composition has, n is the said metal and said metal ion. X is the molar concentration (mol / g) of the carboxy group of the fluororesin (A) contained in the fluororesin composition, and Y is the fluororesin composition. It is the molar concentration (mol / g) of the acid anhydride group of the fluororesin (A) contained in the product. ]   The manufacturing method of the fluororesin crosslinked body of Claim 1 or 2 with which the said fluororesin (A) has a unit based on a fluoro olefin.   The method for producing a crosslinked fluororesin according to claim 3, wherein the fluororesin (A) further has a unit based on an olefin or a unit based on perfluorovinyl ether.   The fluororesin (A) is at least one selected from the group consisting of an ethylene-tetrafluoroethylene copolymer, a tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer, and a tetrafluoroethylene-hexafluoropropylene copolymer. The manufacturing method of the fluororesin crosslinked body as described in any one of Claims 1-4 which exists.   The manufacturing method of the fluororesin crosslinked body as described in any one of Claims 1-5 which forms the said crosslinked structure by melt-kneading the said fluororesin composition.   A method for producing a molded body, wherein the molded body is obtained by melt-molding the fluororesin crosslinked body by the method for producing a crosslinked fluororesin according to any one of claims 1 to 6.   The manufacturing method of the molded object of Claim 7 whose said molded object is a coating | covering material for electric wires. Fluorine-containing resin used for the production of a crosslinked fluorine-containing resin having a crosslinked structure in which a carboxylate ion derived from one or both of an acid anhydride group and a carboxy group and a divalent or higher-valent metal ion are ionically bonded A composition comprising:
A fluorine-containing resin (A) having either one or both of an acid anhydride group and a carboxy group and a compound for forming a crosslinked structure (B),
When the carboxylate ion is derived from an acid anhydride group, the compound for forming a crosslinked structure (B) contains the following compound (B1), the following compound (B1), the following compound (B2), the following compound (B2), and The following compound (B3), or the following compound (B1), the following compound (B2) and the following compound (B3),
When the carboxylate ion is derived from a carboxy group, the compound for forming a crosslinked structure (B) is the following compound (B1), the following compound (B2), or the following compound (B1) and the following compound (B2). A fluorine-containing resin composition characterized by being.
(B1) A compound containing a divalent or higher valent metal ion source capable of ion-bonding with two or more carboxylate ions and capable of opening an acid anhydride group.
(B2) A compound containing a divalent or higher valent metal ion source capable of ion-bonding with two or more carboxylate ions (excluding the compound (B1)).
(B3) A compound capable of ring opening of an acid anhydride group (excluding the compound (B1)). The molar concentration of the acid anhydride group and the carboxyl group that the fluororesin (A) has, and the molar concentration of the metal that the compound for forming a crosslinked structure (B) has satisfy the following formula (1). The fluorine-containing resin composition described in 1.
0.01 ≦ (Z × n) / (X + 2Y) ≦ 1,000 (1)
[In Formula (1), Z is the molar concentration (mol / g) of the metal which the said compound for bridge | crosslinking structure formation (B) contained in the said fluororesin composition has, n is the said metal and said metal ion. X is the molar concentration (mol / g) of the carboxy group of the fluororesin (A) contained in the fluororesin composition, and Y is the fluororesin composition. It is the molar concentration (mol / g) of the acid anhydride group of the fluororesin (A) contained in the product. ]   The fluororesin (A) is at least one selected from the group consisting of an ethylene-tetrafluoroethylene copolymer, a tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer, and a tetrafluoroethylene-hexafluoropropylene copolymer. The fluorine-containing resin composition according to claim 9 or 10.