WO2023120659A1

WO2023120659A1 - Fluororesin composition

Info

Publication number: WO2023120659A1
Application number: PCT/JP2022/047412
Authority: WO
Inventors: 充眞川浪; 真治和田
Original assignee: Ａｇｃ株式会社
Priority date: 2021-12-23
Filing date: 2022-12-22
Publication date: 2023-06-29
Also published as: TW202334310A

Abstract

The present invention provides a fluororesin composition which has excellent flame retardance and color fastness.　This fluororesin composition contains: a fluorine resin which does not contain a chlorine atom; and an additive which imparts flame retardancy to the fluorine resin. The tensile strength of the fluorine resin composition is at least 77% of the tensile strength of the fluorine resin, the tensile elongation of the fluorine resin composition is at least 80% of the tensile elongation of the fluorine resin, the Munsell value of the additive is at least 5, and the additive content is 0.1-20.0 mass% of the total mass of the fluorine resin composition.

Description

Fluoropolymer composition

The present invention relates to a fluororesin composition.

Ethylene-tetrafluoroethylene copolymer is used in many applications such as cable covering materials, coating materials, and building structural materials due to its high chemical resistance, heat resistance, and weather resistance. Since ethylene-tetrafluoroethylene copolymers also have good flame retardancy, they are also used in applications where flame retardancy is required. However, in recent years, due to changes in usage environment, revision of related laws and regulations, etc., higher flame retardancy has been required.

Patent Document 1 discloses a highly flame-retardant black ethylene-tetrafluoroethylene copolymer containing 95 to 99.5 parts by mass of an ethylene-tetrafluoroethylene copolymer, 0.5 to 5 parts by mass of a black pigment, and 5 to 20 parts by mass of a flame retardant. Ethylene copolymer paints have been proposed.

Chinese Patent Application Publication No. 111574890

However, although the paint of Patent Document 1 is excellent in flame retardancy, it is black. Therefore, even if a coloring agent other than a black pigment is added, the paint will all be black. A material with such poor colorability is not suitable for applications that require colorability. For example, if the cable covering material is only black, it is very difficult to distinguish each cable in complicated wiring.
Chlorine-free fluororesins other than ethylene-tetrafluoroethylene copolymers have similar problems.

The present invention provides a fluororesin composition that is excellent in flame retardancy and colorability.

The present invention has the following aspects.
[1] A fluororesin composition containing a fluororesin containing no chlorine atoms and an additive that imparts flame retardancy to the fluororesin,
The tensile strength of the fluororesin composition is 77% or more of the tensile strength of the fluororesin,
The tensile elongation of the fluororesin composition is 80% or more with respect to the tensile elongation of the fluororesin,
Munsell brightness of the additive is 5 or more,
A fluororesin composition, wherein the content of the additive is 0.0001 to 20.0% by mass relative to the total mass of the fluororesin composition.
[2] The fluorine of [1], wherein the mass reduction rate is less than 0.3% by mass when the additive is kept in an atmosphere of 28° C. and 80% RH for 14 days and heated in an oven at 150° C. for 1 hour. Resin composition.
[3] The fluororesin contains a partially fluorinated resin,
The fluororesin composition according to [1] or [2], which has the highest content of the partially fluorinated resin among all the fluororesins contained in the fluororesin composition.
[4] The fluororesin comprises a copolymer having units based on tetrafluoroethylene and units based on ethylene,
The fluororesin composition according to any one of [1] to [3], wherein the content of the copolymer is the highest among all the fluororesins contained in the fluororesin composition.
[5] the copolymer has a hydroxyl group at the end of the main chain,
The fluororesin composition according to [4], wherein the content of the hydroxyl group at the end of the main chain is 1 to 50% in terms of area ratio of the hydroxyl group peak to the overtone peak of the CF bond in the infrared absorption spectrum.

According to the present invention, it is possible to provide a fluororesin composition that is excellent in flame retardancy and colorability.

The meanings and definitions of terms are as follows.
For "tensile strength" and "tensile elongation", a dumbbell-shaped test piece (thickness 1 mm) specified in JIS K 6251 is prepared from a sample (fluororesin composition or fluororesin), and the test piece is It is obtained by performing a tensile test under conditions conforming to JIS K 6251.
“Munsell brightness” is the brightness (Value) of the Munsell color system. The Munsell brightness is calculated based on X, Y and Z values measured by a color difference meter.
"Limiting oxygen index" (hereinafter also referred to as "LOI") is an oxygen index measured according to JIS K 7201-2:2007. LOI is an index of the minimum oxygen concentration (% by volume) required for a sample to sustain combustion, and the larger the index, the higher the flame retardance.
"Melting point" is the temperature corresponding to the maximum of the melting peak as measured by differential scanning calorimetry (DSC).
To be "melt moldable" means to exhibit melt flowability.
The term "exhibits melt fluidity" means that there exists a temperature at which the melt flow rate is 0.1 to 1000 g/10 minutes at a temperature 20°C or more higher than the melting point of the resin under the condition of a load of 49 N.
"Melt flow rate" is the melt mass flow rate (MFR) defined in JIS K 7210:1999 (ISO 1133:1997).
"A unit based on a monomer" is a general term for an atomic group directly formed by polymerization of one molecule of a monomer and an atomic group obtained by chemically converting a part of the atomic group.
By "monomer" is meant a compound having a polymerizable carbon-carbon double bond.
"~" indicating a numerical range means that the numerical values before and after it are included as lower and upper limits.
For the numerical ranges disclosed herein, the lower limits and upper limits can be arbitrarily combined to form new numerical ranges.

[Fluororesin composition]
A fluororesin composition according to one embodiment (hereinafter also referred to as “this composition”) comprises a chlorine atom-free fluororesin (hereinafter also referred to as “fluororesin A”) and a flame retardant fluororesin A and an additive that imparts properties (hereinafter also referred to as “additive B”).

<Fluororesin A>
The fluororesin A is not particularly limited as long as it does not contain chlorine atoms. For example, tetrafluoroethylene (hereinafter also referred to as “TFE”), hexafluoropropylene (hereinafter also referred to as “HFP”), perfluoro(alkyl vinyl ether) (hereinafter also referred to as “PAVE”), vinylidene fluoride ( hereinafter also referred to as "VdF") and vinyl fluoride, and polymers having units based on at least one fluorine monomer.

The fluororesin A may be a homopolymer having one type of unit or a copolymer having two or more types of units.
The fluororesin may further have units based on non-fluorine monomers. Examples of non-fluorine monomers include ethylene, propylene, itaconic anhydride, and vinyl acetate. When the fluororesin has units based on non-fluorinated monomers, the number of units based on non-fluorinated monomers may be one or two or more.

As the fluororesin A, a melt-moldable fluororesin is preferable from the viewpoint of excellent moldability of the fluororesin composition.
Examples of melt-moldable fluororesins include copolymers having units based on TFE (hereinafter also referred to as "TFE units") and units based on ethylene (hereinafter also referred to as "E units") (hereinafter referred to as "E units"). , also referred to as “ETFE”), a copolymer having TFE units and units based on PAVE (hereinafter also referred to as “PAVE units”), units based on TFE units and HFP (hereinafter also referred to as “HFP units” ), copolymers having TFE units, PAVE units and HFP units, and polymers having units based on VdF.
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, even more preferably 250 to 270°C. If the melting point of the fluororesin is at least the above lower limit, the composition will be excellent in heat resistance and rigidity at high temperatures. If the melting point of the fluororesin is equal to or less than the above upper limit, the moldability of the present composition is excellent.

The fluororesin A preferably contains a partially fluorinated resin as a main component. "Contained as a main component" indicates that the content is the largest among all fluororesins A contained in the present composition.
Partially fluorinated resins are fluororesins containing hydrogen atoms, and tend to be inferior in flame retardancy, although they are superior in mechanical properties to fully fluorinated resins that do not contain hydrogen atoms. Therefore, when the fluororesin A contains a partially fluorinated resin as a main component, the usefulness of the present invention is further enhanced. The fluororesin A may further contain a fully fluorinated resin.
The content of the partially fluorinated resin is preferably 50% by mass or more, more preferably 80% by mass or more, and may be 100% by mass with respect to the mass of the entire fluororesin A.

Partially fluorinated resins include, for example, polymers having units based on fluoromonomers containing hydrogen atoms, and polymers having units based on fluoromonomers and units based on non-fluoromonomers.
In the partially fluorinated resin, the mass ratio of hydrogen atoms to fluorine atoms (hydrogen atoms/fluorine atoms) is preferably 10/90 to 2/98, more preferably 5/95 to 3/97. If the hydrogen atom/fluorine atom ratio is at least the lower limit, the heat resistance, chemical resistance, and flexibility are excellent. If the ratio of hydrogen atoms/fluorine atoms is equal to or less than the above upper limit, excellent mechanical properties are obtained.

As the partially fluorinated resin, ETFE is preferable from the viewpoint of excellent moldability, electrical properties, mechanical properties, abrasion resistance, and the like.
As ETFE, from the viewpoint of further excellent heat resistance, mechanical properties, and chemical resistance, E units, TFE units, and units based on other monomers other than ethylene and TFE (hereinafter referred to as "other monomer units ”) is preferred.

The other monomer is not particularly limited as long as it can be copolymerized with ethylene and TFE. Examples thereof include the compound represented by Formula 1 described later, the fluorine monomers (excluding TFE) and the non-fluorine monomers (excluding ethylene) described above. Other monomers may be used singly or in combination of two or more.

Other monomer units preferably include units based on compounds represented by the following formula 1 (hereinafter also referred to as "FAE") from the viewpoint of better mechanical properties and thermal stability.
_CH2 =CX( _CF2 ) _nZ Formula 1
In Formula 1, X and Z are each independently a hydrogen atom or a fluorine atom, and n is an integer of 1-10.

X in Formula 1 is preferably a hydrogen atom from the viewpoint of superior flexibility, elongation and strength.
Z in Formula 1 is preferably a fluorine atom from the viewpoint of further excellent heat resistance and chemical resistance.
n in Formula 1 is preferably 2 to 8, more preferably 2 to 6, and even more preferably 2, 4 or 6. When n is at least the lower limit, the mechanical properties and thermal stability of the present composition are further improved. When n is equal to or less than the above upper limit, FAE has sufficient polymerization reactivity.

Preferred specific examples of FAE include, for example, _CH2 =CH( _CF2 ) _2F , _CH2 =CH( _CF2 ) _4F , _CH2 =CH( _CF2 ) _6F , _CH2 =CF( _CF2 ) 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 from the viewpoint of further 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 units to TFE units (E units/TFE units) is preferably 30/70 to 60/40, more preferably 35/65 to 60/40. When the ratio of E units/TFE units is at least the above lower limit, the melting point of ETFE is sufficiently high, and heat resistance and rigidity at high temperatures are excellent. If the E unit/TFE unit is equal to or less than the above upper limit, the chemical resistance is excellent.

The ratio of other monomer units is preferably 0.7 to 5.0 mol%, more preferably 0.9 to 4.0 mol%, relative to the total units constituting ETFE. If the ratio of other monomeric units is at least the above lower limit, the stress crack resistance at high temperatures will be even better. If the ratio of the other monomer units is equal to or less than the above 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 its main chain. ETFE having a hydroxyl group at the main chain end tends to have a better affinity for additive B than ETFE having no hydroxyl group at the main chain end. When the fluororesin A contains ETFE having a hydroxyl group at the main chain end as a main component, the additive B can be well dispersed in the fluororesin A, and the tensile strength retention rate and tensile elongation retention rate, which will be described later, can be easily increased.
The main chain end of ETFE can be confirmed by analyzing ETFE by infrared spectroscopy.

The content of the hydroxyl group at the end of the main chain is the area ratio of the hydroxyl group peak (e.g., 3540 cm ^-1 peak) to the CF bond overtone peak (e.g., 2210 cm ^-1 peak) in the infrared absorption (IR) spectrum. , preferably 1 to 50%, more preferably 3 to 30%. When the content of hydroxyl groups at the ends of the main chain is at least the above lower limit, the dispersibility of additive B is more excellent. If the content of hydroxyl groups at the ends of the main chain is equal to or less than the above upper limit, the heat resistance will be more excellent.
The content of hydroxyl groups at the ends 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, even more preferably 250 to 265°C. When the melting point of ETFE is at least the above lower limit, the heat resistance and rigidity at high temperatures are excellent. If the melting point of ETFE is equal to or less than the above upper limit, moldability will be excellent.
The melting point of ETFE can be adjusted by the molar ratio of E units to TFE units, the ratio of other monomer units to all units constituting ETFE, and the like.

As the fluororesin A, a commercially available one may be used, or one produced by an arbitrary production method may be used.
ETFE can be produced, for example, by the method described in paragraphs [0021] to [0025] of Patent Document 1 and the method described in paragraphs [0036] to [0043] of WO2016/006644.

ETFE having a hydroxyl group at the end of its main chain can be obtained, for example, by using an alcohol as a chain transfer agent when polymerizing a monomer. Specifically, as described in paragraph [0016] of JP-A-2016-043566, when an alcohol is used as a chain transfer agent, the hydroxyl group of the alcohol is introduced to the main chain end of ETFE, An ETFE having hydroxyl terminal groups at the main chain ends is obtained.

<Additive B>
As the additive B, one having a Munsell brightness of 5 or more is used. The Munsell brightness of the additive B is preferably 6 or more. The Munsell brightness of the additive B is preferably as high as possible, and although the upper limit is not particularly limited, it is 9, for example.
The fluororesin A is generally transparent and has excellent colorability. If the Munsell brightness of the additive B is 5 or more, the flame retardancy can be imparted to the fluororesin A without significantly impairing the coloring properties thereof.
The present composition does not contain additive B having a Munsell brightness of less than 5 (eg, carbon black, titanium black).

As the additive B, any additive can be used as long as it can impart flame retardancy to the fluororesin A and has a Munsell brightness of 5 or more. As an additive having a flame retardant effect, an additive having a Munsell brightness of 5 or more is appropriately selected from various additives (for example, flame retardants, flame retardant aids, pigments having a flame retardant effect, etc.). Available.
Examples of the additive B include antimony-based flame retardants such as antimony trioxide; inorganic particles such as aluminum hydroxide, calcium hydroxide, and magnesium hydroxide; brominated flame retardants such as biphenyl and tetrabromobisphenol A; and chlorine atom-containing resins. Additive B may be used alone or in combination of two or more.

Examples of chlorine atom-containing resins include vinyl chloride polymers such as polyvinyl chloride and polyvinylidene chloride, polychlorotrifluoroethylene (PCTFE), units based on E units and chlorotrifluoroethylene (hereinafter also referred to as "CTFE units"). ) (hereinafter also referred to as “ECTFE”).
As the chlorine atom-containing resin, ECTFE is preferable because it is compatible with the fluororesin A and tends to increase the tensile strength retention rate and the tensile elongation retention rate. ECTFE may further contain monomer units other than ethylene units and chlorotrifluoroethylene units. In ECTFE, the molar ratio of ethylene units/CTFE units is, for example, 30/70 to 70/30. The total content of ethylene units and CTFE units is, for example, 90 mol % or more based on the total of all units constituting ECTFE.

The weight loss rate when additive B is held in an atmosphere of 28° C. and 80% RH for 14 days and heated in an oven at 150° C. for 1 hour is preferably less than 0.3% by mass, more preferably less than 0.25% by mass. Preferably, less than 0.2% by mass is more preferable.
The mass reduction rate is an index of water absorbency of the additive B, and varies depending on the material and shape of the additive B. The lower the mass reduction rate, the easier it is to blend with the fluororesin A and the easier it is to disperse in the fluororesin A. If the mass reduction rate is less than 0.3% by mass, the additive B can be well dispersed in the fluororesin A, so that the tensile strength retention rate and tensile elongation retention rate, which will be described later, can be easily increased.

<Other ingredients>
The present composition may further contain other components other than the fluororesin A and the additive B, if necessary, as long as the effects of the present invention are not significantly impaired.
Other components include, for example, glass fiber, ceramic fiber, titanium oxide, PTFE, color masterbatch, phosphoric acid compound, talc, calcium carbonate, antistatic agent, lubricant, and pigment. Other components may be used alone or in combination of two or more.
It is preferable that the present composition does not contain a component having a Munsell brightness of less than 5 in terms of colorability. Therefore, it is preferable that the Munsell brightness of other components is also 5 or more.

<Content of each component>
The content of additive B in the composition is 0.0001 to 20.0% by weight relative to the total weight of the composition. If the content of additive B is at least the above lower limit, flame retardancy is excellent. If the content of the additive B is equal to or less than the above upper limit, the excellent properties of the fluororesin A (chemical resistance, heat resistance, weather resistance, etc.) can be sufficiently exhibited. The content of additive B is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, still more preferably 0.1% by mass or more, and 1% by mass or more relative to the total mass of the present composition. is particularly preferred. The content of additive B is preferably 20% by mass or less, more preferably 15% by mass or less, relative to the total mass of the present composition.

The content of the fluororesin A is 99.9999% by mass or less, preferably 99.999% by mass or less, more preferably 99.99% by mass or less, and 99.9% by mass with respect to the total mass of the present composition. The following are more preferable, and 99% by mass or less is particularly preferable. The content of fluororesin A is preferably 80% by mass or more, more preferably 85% by mass or more, relative to the total mass of the present composition. When the content of the fluororesin A is at least the above lower limit, the excellent properties of the fluororesin A can be sufficiently exhibited. If the content of the fluororesin A is equal to or less than the above upper limit, excellent flame retardancy is obtained.

The content of other components is preferably 5% by mass or less, more preferably 3% by mass or less, and may be 0% by mass, based on the total mass of the composition.

<Characteristics of the present composition>
The tensile strength of this composition is 77% or more of the tensile strength of fluororesin A. If the ratio of the tensile strength of the present composition to the tensile strength of fluororesin A (hereinafter also referred to as "tensile strength retention") is 77% or more, additive B is well dispersed or compatible with fluororesin A. However, the flame retardancy-imparting effect of the additive B is likely to be exhibited. In addition, the durability and the like can be sufficiently ensured, and the practicality is excellent.
The tensile strength retention rate is preferably 80% or more. Although the upper limit of the tensile strength retention rate is not particularly limited, it is, for example, 120%.
The tensile strength retention rate can be adjusted by, for example, the type, content, and particle size of additive B.

The tensile strength of this composition is preferably 30 MPa or higher, more preferably 35 MPa or higher. If the tensile strength is at least the lower limit, the dispersibility is excellent. Although the upper limit is not particularly limited, it may be, for example, 75 MPa, 70 MPa, or 65 MPa.

The tensile elongation of this composition is 80% or more of the tensile elongation of fluororesin A. If the ratio of the tensile elongation of the present composition to the tensile elongation of fluororesin A (hereinafter also referred to as "tensile elongation retention rate") is 80% or more, additive B is well dispersed in fluororesin A. Or, they are compatible with each other, and the effect of imparting flame retardancy by the additive B is likely to be exhibited. In addition, the durability and the like can be sufficiently ensured, and the practicality is excellent.
Tensile elongation retention is preferably 85% or more. Although the upper limit of the tensile elongation retention rate is not particularly limited, it is, for example, 120%.
The tensile elongation retention rate can be adjusted by, for example, the type, content, and particle size of additive B.

The tensile elongation of the present composition is preferably 200-700%, more preferably 300-650%. If the tensile elongation is at least the lower limit, the flexibility is excellent. If the tensile elongation is equal to or less than the upper limit, the shape retention is excellent.

The Munsell brightness of the present composition is preferably 5 or more, more preferably 6 or more. When the Munsell brightness is at least the above lower limit, the colorability is excellent. The Munsell brightness of the present composition is preferably as high as possible in terms of colorability, and the upper limit is not particularly limited, but is 9, for example.

The LOI of this composition is preferably 33% or more, more preferably 35% or more. When the LOI is at least the above lower limit, it is highly useful in applications where flame retardancy is required. The LOI of the present composition is preferably as high as possible in terms of flame retardancy, and although the upper limit is not particularly limited, it is, for example, 60%.

<Method for producing the present composition>
The present composition is produced by mixing the fluororesin A and the additive B such that the tensile strength retention rate and the tensile elongation retention rate are equal to or higher than the above lower limits. At this time, if necessary, other components may be mixed.
The proportions of fluororesin A, additive B, and other components relative to the total mass of all raw materials to be mixed are the same as the proportions of fluororesin A, additive B, and other components relative to the total mass of the composition. .

When the fluororesin A is melt-moldable, the mixing method is preferably a method of melt-kneading the fluororesin A, the additive B, and, if necessary, other components.
The melt-kneading method includes a method using any melt-kneading device.
The melt-kneading device includes a device having a melt-kneading function. The melt-kneading device is preferably a single-screw extruder or a twin-screw extruder which may be equipped with a screw with high kneading effect, more preferably a twin-screw extruder, and a twin-screw extruder equipped with a screw with high kneading effect. Especially preferred. As a screw having a high kneading effect, a screw that has a sufficient kneading effect on the object to be melt-kneaded and does not give excessive shearing force can be selected. L/D of the screw is preferably 20 or more, more preferably 30 to 70, from the viewpoint of kneading effect. "L/D" is a value obtained by dividing the total screw length L (mm) by the screw diameter D (mm).
Specific examples of the melt-kneading apparatus include Laboplastomill kneader (manufactured by Toyo Seiki Seisakusho) and KZW series twin-screw kneading extruder (manufactured by Technobell).

There are no particular restrictions on the method of supplying the fluororesin A and the additive B to the melt-kneading device. The fluororesin A and the additive B may be mixed in advance and supplied to the melt-kneading device, or the fluororesin A and the additive B may be separately supplied to the melt-kneading device. Other ingredients are also the same.

The temperature at which the fluororesin A and the additive B are melt-kneaded (hereinafter also referred to as "melt-kneading temperature") is preferably set according to the fluororesin A and the additive B. The melt-kneading temperature is preferably 220 to 400°C, more preferably 250 to 350°C.

The melt-kneading of the fluororesin A and the additive B is carried out so that the retention of tensile strength and the retention of tensile elongation are equal to or higher than the aforementioned lower limits.
For example, by increasing the melt-kneading temperature, the additive B is easily dispersed in the fluororesin A, and the tensile strength retention rate and the tensile elongation retention rate are likely to be increased. By lowering the melt-kneading temperature, the thermal decomposition of the fluororesin A is less likely to be promoted, and the heat resistance of the resulting composition is further improved.
By increasing the extrusion shear rate, the additive B is easily dispersed in the fluororesin A, and the tensile strength retention rate and tensile elongation retention rate are likely to increase. By lowering the extrusion shear rate, thermal decomposition of the resin can be prevented and the retention of strength and elongation can be increased.
The additive B is easily dispersed in the fluororesin A by lengthening the residence time of the material to be melt-kneaded in the melt-kneader. As a result, the tensile strength retention rate and tensile elongation retention rate tend to increase. When the residence time is shortened, thermal decomposition of the fluororesin A is less likely to be promoted. As a result, the heat resistance of the obtained composition is further improved.

<Application>
The composition can be used, for example, in wire coating materials, piping linings, semiconductor manufacturing equipment members, semiconductor structural materials, release films, packaging films, chemical transport tubes, packings, gaskets, pump linings, automobile fuel lines, tubes, and blow-molded containers. , high-frequency substrates, high-frequency insulating members, 3D printer materials, architectural membrane structures, air filters, hollow fibers, and resin screws. However, the uses of the present composition are not limited to these.

<Effect>
The present composition contains additive B in a predetermined content and has a tensile strength retention rate of 77% or more and a tensile elongation retention rate of 80% or more. Moreover, since the Munsell brightness of the additive B is 5 or more, the composition has a high Munsell brightness and is excellent in colorability.

The present invention will be specifically described below with reference to examples, but the present invention is not limited to the description of the following examples. Examples 1, 6-8, 12-16 are comparative examples. Examples 2-5 and 9-11 are examples.

〔Evaluation methods〕
<LOI>
LOI was measured according to JIS K 7201-2:2007.

<Munsell brightness>
The Munsell brightness was obtained by measuring the XYZ values with a color difference meter and converting the XYZ values into Munsell hues.

<Mass reduction rate of additive>
After holding the additive in an atmosphere of 28° C. and 80% RH for 14 days, its mass M ₁ (g) was measured. After this additive was placed in 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 equation. The smaller the mass reduction rate, the lower the water absorbency of the additive.
Mass reduction rate (%) = ((M ₁ -M ₂ )/M ₁ ) x 100

<Tensile properties>
(Preparation of test piece)
A pressed sheet of 200 mm×200 mm×1 mm thick was produced by melt-molding the fluororesin composition at 320°C. The press sheet was punched into a JIS K 6251 No. 3 dumbbell shape, and then allowed to stand at 23° C. and RH 50% for 24 hours to obtain a test piece A.
A test piece B was obtained in the same manner as the test piece A, except that the 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, using Strograph R-2 (manufactured by Toyo Seiki Co., Ltd.), a tensile test was performed in accordance with JIS K 6251 under the conditions of 200 mm / min to obtain tensile strength (MPa) and tensile Elongation (%) was determined.

(Tensile strength retention rate, tensile elongation retention rate)
From the determined tensile strength and tensile elongation, the tensile strength retention rate and tensile elongation retention rate were determined by the following equations.
Tensile strength retention (%) = (tensile strength of test piece A / tensile strength of test piece B) x 100
Tensile elongation retention rate (%) = (tensile elongation of test piece A / tensile elongation of test piece B) x 100

[Materials used]
ETFE: ETFE obtained in Synthesis Example 1 described later.
Additive B-1: antimony trioxide, "PATOX-M" manufactured by Nippon Seiko Co., Ltd.
Additive B-2: A mixture of antimony trioxide and a brominated flame retardant (ethylenebispentabromobenzene), manufactured by Suzuhiro Chemical Co., Ltd. "FCP-1590".
Additive B-3: ECTFE (manufactured by Solvey, HALOR930LC).
Additive B-4: Zinc borate, U.S.A. S. "Fire Brake 500" manufactured by Borax.
Additive B-5: Aluminum hydroxide (boehmite), "Cerasur BMT-33" manufactured by Kawai Lime Industry Co., Ltd.
Additive B-6: Silicone flame retardant, "Kane Ace MR-01" manufactured by Kaneka Corporation.
Since the additives B-1 to B-6 are all white, it is clear that the Munsell brightness is 5 or more. Therefore, Munsell brightness was not measured.

[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 perfluorobutyl ethylene (hereinafter "PFBE") were added. planted. The temperature was raised to 66° C. while stirring, and a mixed gas of TFE/E=83/17 (mol %) was introduced until the pressure reached 1.5 MPa (gauge). Then, 1048 g of a CF ₃ (CF ₂ ) ₅ H solution with a tert-butyl peroxypivalate concentration of 1% by mass was injected into the autoclave to initiate polymerization. A mixed gas of TFE/E = 54/46 (mol%) and an amount corresponding to 1.4 mol% with respect to the mixed gas so that the pressure in the autoclave is 1.5 MPa (gauge) during polymerization of PFBE was added continuously. When the amount of the mixed gas added reached 27 kg, the autoclave was cooled and part of the residual monomer gas was purged to obtain slurry 1 of ETFE. 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 charged with 77 kg of water. Next, the temperature was raised to 105° C. with stirring, and the granulated powdery dried ETFE product 1 was collected while removing the solvent by distillation to obtain ETFE having a hydroxyl group at the end of the main chain.
The obtained copolymer composition of ETFE was E unit/TFE unit (molar ratio)=54.1/45.9. The PFBE unit was 1.4 mol % with respect to all units constituting ETFE. The melting point was 259°C. MFR was 9.8 g/10 minutes. The hydrogen atom/fluorine atom mass ratio obtained from the copolymer composition was 4/96. The content of hydroxyl groups at the ends of the main chain was 9% with respect to the overtone peak of the C—F bond in terms of the area ratio of the IR spectrum of ETFE.

[Examples 1 to 16]
ETFE and the additives shown in Table 1 were mixed so that the final additive content was the value shown in Table 1, and kneaded with a twin-screw extruder to obtain a fluororesin composition. The additive content is the ratio (% by mass) of the additive to the total mass of the fluororesin composition.
The obtained fluororesin composition was evaluated for tensile properties, LOI, and Munsell brightness. Table 1 shows the results. For Examples 12 to 16, the tensile strength and tensile elongation were low, and the LOI was not measured because they were poor in practical use.

Examples 2 to 5 and 9 to 11 had high LOI and excellent flame retardancy compared to Example 1, which consisted of only the fluororesin. In addition, the Munsell brightness of the entire fluororesin composition was high, and the colorability was excellent.
On the other hand, Examples 6 to 8, which had a tensile strength retention rate of less than 77% and a tensile elongation retention rate of less than 80%, were inferior in flame retardancy.

This application claims priority based on Japanese Patent Application No. 2021-209651 filed on December 23, 2021, and the entire contents of the same Japanese application are incorporated herein by reference.

Claims

A fluororesin composition containing a fluororesin containing no chlorine atoms and an additive that imparts flame retardancy to the fluororesin,
The tensile strength of the fluororesin composition is 77% or more of the tensile strength of the fluororesin,
The tensile elongation of the fluororesin composition is 80% or more with respect to the tensile elongation of the fluororesin,
Munsell brightness of the additive is 5 or more,
A fluororesin composition, wherein the content of the additive is 0.0001 to 20.0% by mass relative to the total mass of the fluororesin composition.
2. The fluororesin according to claim 1, wherein the weight loss rate is less than 0.3% by mass when the additive is held in an atmosphere of 28° C. and 80% RH for 14 days and heated in an oven at 150° C. for 1 hour. Composition.
The fluororesin contains a partially fluorinated resin,
2. The fluororesin composition according to claim 1, wherein the partially fluorinated resin has the highest content among all the fluororesins contained in the fluororesin composition.
The fluororesin comprises a copolymer having units based on tetrafluoroethylene and units based on ethylene,
2. The fluororesin composition according to claim 1, wherein the copolymer has the highest content among all the fluororesins contained in the fluororesin composition.
the copolymer has a hydroxyl group at the end of the main chain,
5. The fluororesin composition according to claim 4, wherein the content of the hydroxyl group at the end of the main chain is 1 to 50% in terms of area ratio of the hydroxyl group peak to the overtone peak of the CF bond in the infrared absorption spectrum. .