TW202334309A - Fluororesin composition - Google Patents

Abstract

The present invention provides a fluororesin composition having excellent flame retardancy and chemical resistance. The fluororesin composition of the present invention contains a fluororesin and an additive for imparting flame retardancy to the fluororesin. The additive is a carbon-containing inorganic material. The additive content is 0.0001-20 mass% relative to the total mass of the fluororesin composition, and the limiting oxygen index is 35% or greater.

Description

Fluorine resin composition

The present invention relates to a fluororesin composition.

Because fluororesin has high chemical resistance, it is used in many applications such as cable covering materials, coating materials, and building structural materials. Since fluororesin also has good flame retardancy, it is also used in applications requiring flame retardancy. However, recently, due to changes in the use environment, revision of relevant regulations, etc., higher flame retardancy is required.

Patent Document 1 discloses a highly flame-retardant black ethylene-tetrafluoroethylene copolymer coating, which contains 95 to 99.5 parts by mass of ethylene-tetrafluoroethylene copolymer, 0.5 to 5 parts by mass of black pigment, 5 to 20 parts by mass. parts by mass of flame retardant. Copper chrome black is used as the black pigment. [Prior technical literature] [Patent Document]

[Patent Document 1] Chinese Patent Application Publication No. 111574890 Specification

[Problem to be solved by the invention]

However, in order to obtain sufficient flame retardancy in the coating of Patent Document 1, the content of the flame retardant is increased, the content of the fluororesin is relatively reduced, and the chemical resistance is reduced.

The present invention provides a fluororesin composition excellent in flame retardancy and chemical resistance. [Technical means to solve problems]

The present invention has the following aspects. [1] A fluororesin composition, characterized in that it contains a fluororesin and an additive that imparts flame retardancy to the fluororesin, The above additives are carbon-containing inorganic substances. The content of the above additives is 0.0001 to 20% by mass relative to the total mass of the above fluororesin composition, and The limiting oxygen index is above 35%. [2] The fluororesin composition according to [1], wherein the tensile strength of the fluororesin composition is 80% or more relative to the tensile strength of the fluororesin, and The tensile elongation of the fluororesin composition is 80% or more relative to the tensile elongation of the fluororesin. [3] The fluororesin composition of [1] or [2], wherein the mass reduction rate of the above additives maintained in an environment of 28°C and 80% RH for 14 days when heated in an oven at 150°C for 1 hour is not Up to 0.3 mass%. [4] The fluororesin composition according to any one of [1] to [3], wherein the above-mentioned fluororesin contains a partially fluorinated resin, and Among all the above-mentioned fluororesins contained in the above-mentioned fluororesin composition, the content of the above-mentioned partially fluorinated resin is the largest. [5] The fluororesin composition according to any one of [1] to [4], wherein the above fluororesin contains a copolymer having a tetrafluoroethylene-based unit and an ethylene-based unit, and Among all the above-mentioned fluororesins contained in the above-mentioned fluororesin composition, the content of the above-mentioned copolymer is the largest. [6] The fluororesin composition according to [5], wherein the copolymer has a hydroxyl group at the end of the main chain. [Effects of the invention]

According to the present invention, a fluororesin composition excellent in flame retardancy and chemical resistance can be provided.

The meanings and definitions of terms are as follows. "Limiting Oxygen Index" (hereinafter, also referred to as "LOI") is the oxygen index measured in accordance with JIS K 7201-2:2007. LOI is obtained by indexing the minimum oxygen concentration (volume %) required for continuous combustion of the sample. The larger the index, the higher the flame retardancy. "Tensile strength" and "tensile elongation" are measured in accordance with JIS K 6251 by making a dumbbell-shaped test piece (thickness: 1 mm) from the sample (fluororesin composition or fluororesin). It is obtained by conducting a tensile test on the test piece under the conditions. "Melting point" is the temperature corresponding to the maximum value of the melting peak measured by differential scanning calorimetry (DSC). "Melt formable" means exhibiting melt flowability. "Exhibiting melt fluidity" means that under a load of 49 N, at a temperature 20°C or more higher than the melting point of the resin, there is a temperature at which the melt flow rate becomes 0.1 to 1000 g/10 minutes. "Melt flow rate" is the melt mass flow rate (MFR) specified in JIS K 7210: 1999 (ISO 1133: 1997). "Unit based on monomer" is a general term for the atomic group directly formed by the polymerization of one molecule of monomer and the atomic group obtained by chemically converting part of the atomic group. "Monomer" means a compound having a polymerizable carbon-carbon double bond. "～" indicating a numerical range means that the numerical values stated before and after it are included as the lower limit and upper limit. The numerical range disclosed in this specification can be arbitrarily combined with its lower limit value and upper limit value to form a new numerical range.

[Fluororesin composition] A fluororesin composition according to one embodiment (hereinafter also referred to as "this composition") contains a fluororesin and an additive (hereinafter also referred to as "additive") that imparts flame retardancy to the fluororesin.

＜Fluororesin＞ Examples of the fluororesin include those based on tetrafluoroethylene (hereinafter also referred to as "TFE"), hexafluoropropylene (hereinafter also referred to as "HFP"), perfluoro (alkyl vinyl ether) (hereinafter, also referred to as "PAVE"), chlorotrifluoroethylene (hereinafter, also referred to as "CTFE"), vinylidene fluoride (hereinafter, also referred to as "VdF") and vinyl fluoride. The unit of the polymer.

The fluororesin may be a homopolymer having one unit or a copolymer having two or more units. The fluororesin may further have units based on non-fluorine monomers. Examples of the non-fluorine monomer include ethylene (hereinafter also referred to as "E"), propylene, itaconic anhydride, and vinyl acetate. When the fluororesin has a unit based on a non-fluorine monomer, the number of units based on the non-fluorine monomer may be only one type or two or more types.

As the fluororesin, a melt-moldable fluororesin is preferred in terms of excellent formability of the fluororesin composition. Examples of the melt-moldable fluororesin include a copolymer (hereinafter, a unit based on TFE (hereinafter, also referred to as "TFE unit") and a unit based on E (hereinafter, also referred to as "E unit")). , also referred to as "ETFE"), copolymers having TFE units and PAVE-based units (hereinafter, also referred to as "PAVE units"), copolymers having TFE units and HFP-based units (hereinafter, also referred to as "HFP units") ), copolymers with TFE units, PAVE units and HFP units, polymers with CTFE-based units, copolymers with CTFE-based units and E units, polymers with VdF-based units, etc. The MFR of the melt-moldable fluororesin is preferably 0.1 to 70 g/10 minutes, more preferably 3 to 40 g/10 minutes.

The melt-moldable fluororesin preferably has a melting point. The melting point of the fluororesin is preferably 160 to 325°C, more preferably 220 to 320°C, and further preferably 250 to 270°C. If the melting point of the fluororesin is equal to or higher than the above-mentioned lower limit, the present composition will have excellent heat resistance and high-temperature rigidity. If the melting point of the fluororesin is below the above-mentioned upper limit, the present composition will have excellent formability.

The fluororesin preferably contains a partially fluorinated resin as a main component. "Containing a certain component as the main component" means that among all the fluororesins contained in the composition, the content of a certain component is the largest. Partially fluorinated resins are fluororesins that contain hydrogen atoms. Compared with fully fluorinated resins that do not contain hydrogen atoms, although they have excellent mechanical properties, they tend to have poor flame retardancy. Therefore, in the case where the fluororesin contains a partially fluorinated resin as the main component, the usability of the present invention is further improved. The fluororesin may further include fully fluorinated resins. Relative to the mass of the entire fluororesin, the content of the partially fluorinated resin is preferably 50 mass% or more, more preferably 80 mass% or more, and may be 100 mass%.

Examples of the partially fluorinated resin include polymers having units based on fluorine monomers containing hydrogen atoms, polymers having units based on fluorine monomers, and units based on non-fluorine monomers. In the partially fluorinated resin, the mass ratio of hydrogen atoms to fluorine atoms (hydrogen atom/fluorine atom) is preferably 10/90 to 1/99, more preferably 6/94 to 2/98. When the hydrogen atom/fluorine atom is equal to or higher than the above lower limit, heat resistance, chemical resistance, and flexibility will be excellent. When the hydrogen atom/fluorine atom is less than the above upper limit, the mechanical properties will be excellent.

As the partially fluorinated resin, ETFE is preferred in terms of its excellent formability, electrical properties, mechanical properties, wear resistance, etc. In terms of ETFE having more excellent heat resistance, mechanical properties, and chemical resistance, it is preferable to have an E unit, a TFE unit, and a unit based on a monomer other than ethylene and TFE (hereinafter, also referred to as " Copolymers of other monomer units").

Other monomers can be copolymerized with ethylene and TFE and are not particularly limited. Examples thereof include compounds represented by the following formula 1, the above-mentioned fluorine monomers (excluding TFE among them) and non-fluorine monomers (excluding ethylene among them). One type of other monomers may be used alone, or two or more types may be used in combination.

From the viewpoint of more excellent mechanical properties and thermal stability, the other monomer units are preferably units based on the compound represented by the following formula 1 (hereinafter also referred to as "FAE"). CH ₂ =CX(CF ₂ ) _n Z Formula 1 In Formula 1, X and Z are each independently a hydrogen atom or a fluorine atom, and n is an integer from 1 to 10.

In terms of more excellent flexibility, elongation and strength, X in Formula 1 is preferably a hydrogen atom. In terms of more excellent heat resistance and chemical resistance, Z in Formula 1 is preferably a fluorine atom. n in Formula 1 is preferably 2 to 8, more preferably 2 to 6, and still more preferably 2, 4 or 6. If n is more than the above lower limit, the mechanical properties and thermal stability of the present composition will be further excellent. If n is below the above upper limit, FAE has sufficient polymerization reactivity.

Preferable specific examples of FAE include: CH ₂ =CH(CF ₂ ) ₂ F, CH ₂ =CH(CF ₂ ) ₄ F, CH ₂ =CH(CF ₂ ) ₆ F, CH ₂ =CF (CF ₂ ) ₄ F, CH ₂ =CF(CF ₂ ) ₃ H. Among them, CH ₂ =CH(CF ₂ ) ₄ F (hereinafter, also referred to as “PFBE”) is preferable in terms of having more excellent mechanical properties and thermal stability. One type of FAE may be used alone, or two or more types may be used in combination.

In ETFE, the molar ratio of E unit and TFE unit (E unit/TFE unit) is preferably 30/70 to 60/40, more preferably 35/65 to 60/40. If the E unit/TFE unit is equal to or higher than the above lower limit, the melting point of ETFE is sufficiently high and the heat resistance and rigidity at high temperatures are excellent. When the E unit/TFE unit is equal to or less than the above-mentioned upper limit, the chemical resistance will be excellent.

The ratio of other monomer units to all units constituting ETFE is preferably 0.7 to 5.0 mol%, more preferably 0.9 to 4.0 mol%. If the ratio of other monomer units is more than the above-mentioned lower limit, the stress crack resistance at high temperatures will be even more excellent. If the ratio of other monomer units is less than the above-mentioned upper limit, the melting point of ETFE is sufficiently high, and the heat resistance and rigidity at high temperatures are excellent.

ETFE preferably has a hydroxyl group at the end of the main chain. ETFE having a hydroxyl group at the end of the main chain tends to have better affinity with additives than ETFE having no hydroxyl group at the end of the main chain. By making the fluororesin contain ETFE having a hydroxyl group at the end of the main chain as a main component, the additives can be well dispersed in the fluororesin, and the tensile strength retention rate and tensile elongation retention rate described below can be easily improved. The end of the ETFE backbone can be confirmed by analyzing ETFE using infrared spectroscopy.

The content of the hydroxyl group at the end of the main chain is calculated by the area ratio of the hydroxyl peak (for example, the peak at 3540 cm ^-1 ) to the harmonic peak of the CF bond (for example, the peak at 2210 cm ^-1 ) in the infrared absorption (IR) spectrum. Preferably, it is 1-50%, More preferably, it is 3-30%. If the content of the hydroxyl group at the end of the main chain is more than the above lower limit, the dispersibility of the additive will be even better. If the content of the hydroxyl group at the end of the main chain is less than the above upper limit, the heat resistance will be more excellent. The content of hydroxyl groups at the end of the main chain can be adjusted by the molecular weight of ETFE.

The melting point of ETFE is preferably 160 to 320°C, more preferably 245 to 270°C, and further preferably 250 to 265°C. If the melting point of ETFE is equal to or higher than the above lower limit, the heat resistance and rigidity at high temperatures will be excellent. If the melting point of ETFE is below the above upper limit, the formability will be excellent. The melting point of ETFE can be adjusted by the molar ratio of the E unit relative to the TFE unit, the ratio of other monomer units relative to all units constituting ETFE, etc.

A commercially available fluororesin may be used, or a fluororesin manufactured by any manufacturing method may be used. ETFE can be produced by, for example, the method described in paragraphs [0021] to [0025] of Patent Document 1, or the method described in paragraphs [0036] to [0043] of International Publication No. 2016/006644.

ETFE having a hydroxyl group at the end of the main chain can be obtained, for example, by using alcohols as a chain transfer agent when polymerizing monomers. Specifically, as described in paragraph [0016] of Japanese Patent Application Laid-Open No. 2016-043566, when alcohols are used as chain transfer agents, the hydroxyl group of the alcohols is introduced to the end of the main chain of ETFE to obtain ETFE having a terminal group containing a hydroxyl group at the end of the main chain.

＜Additive＞ Additives are carbon-containing inorganic substances. Even a small amount of carbon-containing inorganic substances can impart excellent flame retardancy to the fluororesin composition. Examples of carbon-containing inorganic substances include carbon black, carbon nanotubes, carbon fibers, graphene, fullerene C60, and artificial diamond. One type of carbon-containing inorganic substance may be used alone, or two or more types may be used in combination. As the carbon-containing inorganic substance, carbon black and carbon fiber are preferred in terms of dispersibility.

When the additive that has been maintained at 28°C and 80% RH for 14 days is heated in an oven at 150°C for 1 hour, the mass reduction rate is preferably less than 0.3% by mass, more preferably less than 0.25% by mass, and further preferably less than 0.25% by mass. Preferably, it is less than 0.2% by mass. This mass reduction rate is an indicator of the water absorption of the additive and varies depending on the material and shape of the additive. The smaller the mass reduction rate, the easier it is to fuse with the fluororesin and to be dispersed in the fluororesin. If the mass reduction rate is less than 0.3% by mass, the additives can be well dispersed in the fluororesin, so it is easy to improve the tensile strength retention rate and tensile elongation retention rate described below.

＜Other ingredients＞ The present composition may further contain other components other than the fluororesin and additives as necessary within the range that does not significantly impair the effects of the present invention. Examples of other components include fluorine-containing organic substances, pigments, conductors, glass fibers, glass hollow spheres, silicon, and talc. One type of other components may be used alone, or two or more types may be used in combination.

＜Content of each ingredient＞ In this composition, the content of the additive is 0.0001 to 20 mass% relative to the total mass of the composition. If the content of the additive is more than the above lower limit, the flame retardancy will be excellent. If the additive content is below the above upper limit, the fluororesin content can be increased, resulting in excellent chemical resistance, heat resistance, weather resistance, etc. Relative to the total mass of the composition, the content of the additive is preferably 0.001 mass% or more, more preferably 0.01 mass% or more, and further preferably 1 mass% or more. The content of the additive is preferably 15% by mass or less based on the total mass of the composition.

The content of the fluororesin is 99.9999 mass% or less relative to the total mass of the composition, preferably 99.999 mass% or less, more preferably 99.99 mass% or less, further preferably 99.9 mass% or less, particularly preferably 99 mass%. the following. Relative to the total mass of the composition, the content of the fluororesin is preferably 80 mass% or more, more preferably 85 mass% or more. When the content of the fluororesin is equal to or higher than the above-mentioned lower limit, chemical resistance, heat resistance, weather resistance, etc. will be excellent. When the content of the fluororesin is below the above upper limit, the flame retardancy will be excellent.

Relative to the total mass of the composition, the content of other components is preferably 5 mass% or less, more preferably 3 mass% or less, and can be 0 mass%.

＜Characteristics of this composition＞ The LOI of this composition is more than 35%, preferably more than 37%. If the LOI is above the above lower limit, the usability in applications requiring flame retardancy is high. In terms of flame retardancy, the higher the LOI of the composition, the better. The upper limit is not particularly limited, for example, it is 95%.

Relative to the tensile strength of the fluororesin, the tensile strength of the present composition is preferably 80% or more, more preferably 90% or more. If the ratio of the tensile strength of the present composition to the tensile strength of the fluororesin (hereinafter also referred to as "tensile strength retention rate") is more than the above lower limit, the additive is well dispersed or soluble in the fluororesin. , it is easy to exert the flame retardant imparting effect obtained by additives. In addition, durability and the like can be fully ensured, and the practicality is excellent. The upper limit of the tensile strength retention rate is not particularly limited, but is, for example, 120%. The tensile strength retention rate can be adjusted, for example, by the type and content of additives, and the particle size.

The tensile strength of this composition is preferably 30 MPa or more, more preferably 35 MPa or more. If the tensile strength is equal to or higher than the above lower limit, the dispersibility will be excellent. The upper limit is not particularly limited, but is, for example, 75 MPa.

Relative to the tensile elongation of the fluororesin, the tensile elongation of the present composition is preferably 80% or more, more preferably 95% or more. If the ratio of the tensile elongation of the present composition to the tensile elongation of the fluororesin (hereinafter also referred to as "tensile elongation retention") is more than the above lower limit, the additives are well dispersed or miscible. In fluororesins, the flame retardancy imparting effect obtained by additives is easily exerted. In addition, durability and the like can be fully ensured, and the practicality is excellent. The upper limit of the tensile elongation retention is not particularly limited, but is, for example, 120%. The tensile elongation retention rate can be adjusted by, for example, the type and content of the additive, and the particle size.

The tensile elongation of the composition is preferably above 350%, more preferably above 385%. If the tensile elongation is equal to or higher than the above-mentioned lower limit, the mechanical properties will be excellent and the film will be less likely to break when an external force is applied.

＜Method for producing this composition＞ This composition is produced by mixing a fluororesin and additives, for example. It is also possible to mix a masterbatch prepared by mixing a part of the fluororesin and additives in advance and the remaining fluororesin. Other ingredients can be mixed as needed. The ratio of each of the fluororesin, additives, and other components to the total mass of all the raw materials mixed is the same as the ratio of each of the fluororesin, additives, and other components to the total mass of the composition.

When the fluororesin can be melt-formed, a preferred mixing method is a method of melt-kneading the fluororesin, additives, and other components if necessary. An example of the melt-kneading method is a method using any melt-kneading device. Examples of the melt-kneading device include devices having a melt-kneading function. As the melt-kneading device, a single-screw extruder or a twin-screw extruder equipped with a screw with a high kneading effect is preferred, a twin-screw extruder is more preferably used, and a twin-screw extruder with a screw with a high kneading effect is particularly preferred. Shaft extruder. As a screw with a high kneading effect, you can choose a screw that has a sufficient kneading effect on the melt-kneaded object and does not exert excessive shear force. In terms of kneading effect, the L/D of the screw is preferably 20 or more, and more preferably 30 to 70. "L/D" is the value obtained by dividing the total screw length L (mm) by the screw diameter D (mm). Specific examples of the melt-kneading device include a Labo Plastomill kneader (manufactured by Toyo Seiki Seisakusho Co., Ltd.) and a KZW Series twin-shaft kneading extruder (manufactured by Technovel Co., Ltd.).

The method of supplying the fluororesin and additives to the melt-kneading device is not particularly limited. The fluororesin and the additives may be mixed in advance and supplied to the melting and kneading device, or the fluororesin and the additives may be separately supplied to the melting and kneading device. The same goes for other ingredients.

The temperature when melting and kneading the fluororesin and additives (hereinafter also referred to as "melt and kneading temperature") is preferably set according to the fluororesin and additives. The melting and kneading temperature is preferably 220 to 400°C, more preferably 250 to 350°C.

The melt-kneading of the fluororesin and the additives is preferably carried out so that the tensile strength retention rate and the tensile elongation retention rate are equal to or above the above-mentioned lower limits. For example, by raising the melting and kneading temperature, the additives are easily dispersed in the fluororesin, and the tensile strength retention rate and tensile elongation retention rate are easily improved. By lowering the melting and kneading temperature, thermal decomposition of the fluororesin is less likely to be promoted, and the resulting composition has better heat resistance. By increasing the extrusion shear speed, the additives are easily dispersed in the fluororesin, and the tensile strength retention rate and tensile elongation retention rate are easily improved. By reducing the extrusion shear speed, the decomposition of the main chain can be inhibited. If the residence time of the melt-kneading target object in the melt-kneading device is extended, the additives will be easily dispersed in the fluororesin. As a result, the tensile strength retention rate and the tensile elongation retention rate are easily improved. If the residence time is shortened, thermal decomposition of the fluororesin will be less likely to be promoted. As a result, the obtained composition is more excellent in heat resistance.

＜Use＞ The present composition can be used, for example, in wire covering materials, pipe linings, semiconductor manufacturing equipment components, semiconductor structural materials, release films, packaging films, chemical liquid delivery pipes, gaskets, gaskets, pump linings, automobile fuel lines, pipes, Blow molded containers, high-frequency substrates, high-frequency insulating members, materials for 3D (three-dimensional, three-dimensional) printers, membrane structures for buildings, air filters, hollow fibers, and resin screws. However, the use of the present composition is not limited to these.

＜Effect＞ This composition contains a carbon-containing inorganic substance as an additive in a content of 0.1% by mass or more and has an LOI of 35% or more, so it has excellent flame retardancy. In addition, since the content of the carbon-containing inorganic substance as an additive is 20% by mass or less, the chemical resistance is excellent. [Example]

Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to the description of the following examples. Example 1 is a comparative example. Examples 2 to 6 are examples.

[Evaluation method] ＜LOI＞ LOI is measured according to JIS K 7201-2:2007.

<Mass reduction rate of additive> After maintaining the additive in an environment of 28° C. and 80% RH for 14 days, its mass M ₁ (g) was measured. After the additive was put into an oven at 150° C. and heated for 1 hour, its mass M ₂ (g) was measured, and the mass reduction rate was determined by the following formula. The smaller the mass reduction rate, the lower the water absorption of the additive. Mass reduction rate (%) = ((M ₁ -M ₂ )/M ₁ )×100

＜Tensile properties＞ (Preparation of test pieces) By melt-molding the fluororesin composition at 320°C, a pressed sheet of 200 mm×200 mm×1 mm thickness was produced. The obtained pressed sheet was punched into a JIS K 6251 No. 3 dumbbell shape, and then left to stand at 23°C RH50% for 24 hours to obtain a test piece A. Test piece B was obtained in the same manner as test piece A except that a fluororesin blended in the fluororesin composition was used instead of the fluororesin composition.

(tensile test) For each of the obtained test pieces A and B, a tensile test was performed under the conditions of 200 mm/min in accordance with JIS K 6251 using Strograph R-2 (manufactured by Toyo Seiki Co., Ltd.) to obtain the tensile strength (MPa) and Tensile elongation (%).

(Tensile strength retention, tensile elongation retention) Based on the determined tensile strength and tensile elongation, the tensile strength retention rate and the tensile elongation retention rate were determined by the following formulas. Tensile strength retention rate (%) = (tensile strength of test piece A/tensile strength of test piece B) × 100 Tensile elongation retention (%) = (tensile elongation of test piece A/tensile elongation of test piece B) × 100

[Materials used] ETFE: the synthetic product obtained in Synthesis Example 1 below. Additive masterbatch: particles of a mixture of ETFE and carbon black (CB) (CB content: 15% by mass relative to the total mass of the particles).

[Synthesis Example 1] After degassing a 430-liter stainless steel autoclave, 417.2 kg of CF ₃ (CF ₂ ) ₅ H, 3.8 kg of methanol, and 1.9 kg of perfluorobutylethylene (hereinafter referred to as "PFBE"). While stirring, the temperature was raised to 66°C, and a mixed gas of TFE/E=83/17 (mol%) was introduced until it reached 1.5 MPa (gauge). Then, 1048 g of a CF ₃ (CF ₂ ) ₅ H solution with a concentration of tert-butyl peroxypivalate of 1% by mass was injected into the autoclave to start polymerization. During the polymerization process, a mixed gas of TFE/E=54/46 (mol%) and an amount equivalent to 1.4 mol% of the above mixed gas were continuously added so that the pressure in the autoclave became 1.5 MPa (gauge). PFBE. When the added amount of the above mixed gas reaches 27 kg, the autoclave is cooled and part of the residual monomer gas is removed, thereby obtaining ETFE slurry 1. 120 kg of the obtained slurry 1 was stored in a storage tank, and the obtained ETFE slurry was put into a 220 L (liter) granulation tank containing 77 kg of water. Then, while stirring, the temperature was raised to 105° C., the solvent was distilled off, and the granulated powdered ETFE dried product 1 was recovered, thereby obtaining ETFE having a hydroxyl group at the end of the main chain. The copolymer composition of the obtained ETFE was E unit/TFE unit (molar ratio)=54.1/45.9. Relative to all the units that make up ETFE, PFBE units are 1.4 mol%. The melting point is 259℃. MFR is 9.8 g/10 minutes. The mass ratio of hydrogen atoms/fluorine atoms calculated from the copolymer composition was 4/96. The content of the hydroxyl group at the end of the main chain is calculated as the area ratio of the IR spectrum of ETFE, which is 9% relative to the harmonic peak of the CF bond.

[Examples 1 to 6] ETFE and the additive masterbatch were mixed so that the final content of the additive masterbatch becomes the value shown in Table 1, and kneaded using a twin-screw extruder to obtain a fluororesin composition. Table 1 also records the CB-converted content of the additive masterbatch. The content of each of the additive masterbatch and CB is a ratio (mass %) to the total mass of the fluororesin composition. The obtained fluororesin composition was evaluated for tensile properties and LOI. The results are shown in Table 1.

[Table 1] additives Additive Masterbatch Tensile strength retention rate (%) Tensile strength(MPa) Tensile elongation retention (%) Tensile elongation (%) LOI mass reduction rate content CB conversion content example 1 - 0% 0% 100.0 56.0 100.0 483 30.2 Example 2 0.06% 10% 1.5% 99.8 55.9 101.9 360 38.6 Example 3 0.06% 15% 2.25% 101.1 56.6 104.6 363 42.8 Example 4 0.06% 20% 3% 96.6 54.1 95.0 459 56.4 Example 5 0.06% 40% 6% 86.6 48.5 89.2 431 58.2 Example 6 0.06% 60% 9% 79.8 42.0 83.1 395 62.9

Compared with Example 1, which is composed only of fluororesin, Examples 2 to 6 have higher LOI and excellent flame retardancy. In addition, since the content of the additive is 20% by mass or less, it can be seen that the entire fluororesin composition has excellent chemical resistance. [Industrial availability]

According to the present invention, a fluororesin composition excellent in flame retardancy and chemical resistance can be provided.

This case claims priority based on Japanese Patent Application No. 2021-209643 filed on December 23, 2021, and the entire content of the Japanese application is incorporated into this case by reference.

Claims (6)

A fluororesin composition, characterized in that it contains a fluororesin and an additive that imparts flame retardancy to the fluororesin, The above additives are carbon-containing inorganic substances. The content of the above additives is 0.0001 to 20% by mass relative to the total mass of the above fluororesin composition, and The limiting oxygen index is above 35%. The fluororesin composition of claim 1, wherein the tensile strength of the fluororesin composition is 80% or more relative to the tensile strength of the fluororesin, and The tensile elongation of the fluororesin composition is 80% or more relative to the tensile elongation of the fluororesin. For example, the fluororesin composition of Claim 1 or 2, wherein the mass reduction rate of the above-mentioned additives maintained in an environment of 28°C and 80% RH for 14 days when heated in an oven at 150°C for 1 hour does not reach 0.3% by mass. The fluororesin composition according to any one of claims 1 to 3, wherein the above fluororesin contains a partially fluorinated resin, and Among all the above-mentioned fluororesins contained in the above-mentioned fluororesin composition, the content of the above-mentioned partially fluorinated resin is the largest. The fluororesin composition according to any one of claims 1 to 4, wherein the fluororesin includes a copolymer having a tetrafluoroethylene-based unit and an ethylene-based unit, and Among all the above-mentioned fluororesins contained in the above-mentioned fluororesin composition, the content of the above-mentioned copolymer is the largest. The fluororesin composition of claim 5, wherein the copolymer has a hydroxyl group at the end of the main chain.