JPS63278915A - Flame-retardant resin film - Google Patents

Abstract

PURPOSE:To obtain a resin film which is excellent in flame retardance and flexibility, by melt-molding a copolymer consisting of tetrafluoroethylene, chlorotrifluoroethylene and ethylene. CONSTITUTION:The title product is a flame-retardant resin film obtained by melt-molding a single copolymer consisting of 10-60mol.% tetrafluoroethylene, 20-60mol.% chlorotrifluoroethylene and 20-40mol.% ethylene or its mixture with additives (e.g. ultraviolet absorber, pigment, etc.). This film is excellent in flame retardance and flexibility. This fluorine-containing copolymer has a wide difference between its heat decomposition point and melting point, and its melting point is relatively low, so that it is excellent in moldability and can be blended smoothly with various additives, particularly with organic additives. Furthermore, its mechanical characteristics can be improved easily upon elongation. The title product is useful as film for solar radiation equipment, marking film, mold release film, insulating film, etc.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a flame-retardant resin film.

[Prior art] Resin films with excellent flame retardancy include polytetrafluoroethylene, tetrafluoroethylene-perfluorovinyl ether copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and tetrafluoroethylene-perfluoroethylene. Films made of perfluoropolymers such as vinyl ether-hexafluorobrobylene terpolymers are known. However, these films require high temperatures of 350°C or higher to form, which not only poses equipment limitations, but also poses the problem of difficulty in blending various additives, especially organic additives such as ultraviolet absorbers. was there.

On the other hand, films made of fluororesins such as ethylene-tetrafluoroethylene copolymer, ethylene-chlorotrifluoroethylene copolymer, or polyvinylidene fluoride are also known, but they lack flexibility and Another problem was that it had poor flame retardancy.

[Problems to be Solved by the Invention] The purpose of the present invention is to solve the problems in the prior art as described above, and to provide a flexible fluororesin film with excellent flame retardancy. be.

[Means for Solving the Problems] The inventors of the present invention have conducted extensive studies on these problems and found that the copolymer composition is 10 to 60 mol% of tetrafluoroethylene and chlorotrifluoride. Fluoroethylene 20-60 mol%
, an interesting finding that a film made by melt-molding a copolymer containing 20 to 40 mol% ethylene alone or a mixture of this and an additive component has excellent flame retardancy and is highly flexible. This discovery led to the present invention.

In the present invention, it is important to use a fluorine-containing copolymer in which the three components of tetrafluoroethylene, chlorotrifluoroethylene, and ethylene are copolymerized in a specific composition ratio.

The specific fluorine-containing copolymer used in the present invention has a large difference between the thermal decomposition point and the melting point, and has excellent melt moldability. That is, the thermal decomposition point is usually 340°C or higher, and in a preferred embodiment, 36°C.
It is about 0 to 370°C, and the melting point varies depending on the above thermal decomposition point and the molecular weight described below, but it is usually about 170 to 370°C.
Relatively low at 230℃, the difference between melting point and decomposition point is 120℃
It's bigger than that. In addition, this copolymer has an oxygen index of 60
As mentioned above, it has excellent flame retardancy, for example, about 76 to 80, and has a bending elasticity of 6 x IO at room temperature.
kg/cm" or less, and is highly flexible. On the other hand, when using a copolymer with a copolymer composition outside the above range, the difference between the melting point and thermal decomposition point is narrow. The molecular weight of the copolymer to be used is not particularly limited, but it is undesirable because it causes the melting point to increase, resulting in a decrease in melt moldability, flame retardancy, and flexibility.The molecular weight of the copolymer used is not particularly limited, but it from the surface, at the volumetric flow rate specified below.
Approximately 200 mm"/paper, especially 10 to 150 mm and 37 seconds is preferable. In the present invention, the volumetric flow rate is a guideline for molecular weight, and is measured using a Koka type flow tester at a predetermined temperature of 300°C and a predetermined load of 30 kg/cm". This value is expressed as the volume of the molten sample extruded per unit time when 1 g of sample is extruded from a nozzle with a nozzle diameter of 1111 mm and a land length of 2 mm.

In order to produce such a fluorine-containing copolymer, conventionally known or well-known polymerization methods for copolymers such as tetrafluoroethylene and chlorotrifluoroethylene can be employed without particular limitation. polymerization,
Any method such as suspension polymerization or emulsion polymerization can be used.

Polymerization DR initiators that can be used in solution polymerization include 2, for example di(chlorofluoroacyl)-peroxide, di(perfluoroacyl)-peroxide, di(ω-hydroperfluoroacyl)-peroxide, t- Examples include butyl peroxyisobutyrate, diisobrobyl peroxydicarbonate, and the like. Further, as a solvent, a chlorofluoroalkane is used, and examples of the chlorofluoroalkane include trichlorofluoromethane, dichlorodifluoromethane, and dichlorofluoromethane.

Examples include chlorodifluoromethane, trifluoromethane, trichlorotrifluoroethane, dichlorotetrafluoroethane, chloropentafluoroethane, difluoroethane, and the like.

Furthermore, if necessary, a chain transfer agent may be added to adjust the molecular weight. For example, a chain transfer agent such as carbon tetrachloride, n-pentane, n-hexane, isopentane, trichlorofluoromethane, or methanol may be used. preferable.

In suspension polymerization, the same radical polymerization initiators as mentioned above for solution polymerization can be used, and the solvent used is a mixture of water and a chlorofluoroalkane as mentioned above for solution polymerization, and the mixing ratio is usually Water:chlorofluoroalkane=l:9 to 9:1, preferably l by weight ratio
:5 to 5:1. Furthermore, as the chain transfer agent, it is desirable to use the solution-polymerized one described above. Additionally, fluorocarbon emulsifiers, such as C
,F , ,C00Nl+, ,C,F , ? C00
N11. etc. may be added.

Radical polymerization initiators that can be used in emulsion polymerization include:
A conventional water-soluble radical polymerization initiator is used. For example, disuccinic acid peroxide, ammonium persulfate, potassium persulfate, t-butylperoxyisobutyrate, 2,2'-diguanyl-2,2'-
Such as azobroban dihydrochlorite. As the solvent, water alone or a mixed solvent of water and an organic solvent can be used. The organic solvent is t-butanol.

Difluoroethane, trichlorotrifluoroethane, etc. can be used, and as the chain transfer agent, those mentioned for solution polymerization can be used. The emulsifier is preferably a fluorocarbon emulsifier, such as C, F, C00N11. , C
,F,,C00NI1. etc.

The polymerization conditions in the various polymerization methods described above are also not particularly limited, and can be adopted over a wide range.

In the present invention, film forming is carried out by melt-molding the above-mentioned fluorine-containing copolymer alone or a mixture thereof with various additive components described below, and extrusion molding is preferably employed from the viewpoint of productivity. Ru. Although the molding conditions are not particularly limited, the molding temperature is selected to be between the melting point and the thermal decomposition point, and is usually about 180 to 370°C.

Depending on the application, the film of the present invention can contain ultraviolet absorbers, heat stabilizers, reinforcing agents, focusing agents, lubricants, pigments, and other appropriate additives, and in particular, organic additives such as ultraviolet absorbers. It has the advantage that it can be blended smoothly. That is, since melt molding is possible at a relatively low temperature, it is possible to suppress the decomposition or volatilization of added components during molding, and it becomes easy to ensure a desired blending amount. It goes without saying that the film of the present invention can be used alone as a protective coating, but for a wide range of commercial applications, it is also preferable to use it in a layered manner with a general-purpose synthetic resin film or sheet material. .

Even in the non-oriented state after melt molding, the film of the present invention
Although it has various excellent properties, it is also possible to improve the mechanical strength by stretching it -axially or biaxially to form an oriented film. In this case, from the viewpoint of achieving smooth stretching without cutting or roughening, 20 to 16
It is preferred to employ a stretching temperature in the range of 0°C, especially 40 to 110°C. As a stretching method, various methods can be adopted, such as a method using a speed difference between two pairs of rolls, a uniaxial stretching method such as a method using a tenter clip, a sequential two-wheel stretching method, a simultaneous biaxial stretching method, etc. . The stretching ratio is also not particularly limited, but depending on the purpose, a range of usually 1.05 to 20 times, particularly 1.1 to 10 times, can be adopted. It is possible to achieve tensile failure rates of the order of %.

[Examples] Next, the present invention will be explained in more detail by showing Examples and Comparative Examples, but it goes without saying that the present invention is not limited by such explanations. The melting point, thermal decomposition point, copolymer composition, oxygen index, and flexural modulus were each measured by the following methods.

Using a rupture DT-3D pyrolysis apparatus manufactured by Shimadzu, the temperature was raised from room temperature at a heating rate of 10 °C/min, the maximum value of the melting curve was taken as the melting point, and the decrease in the thermogravimetric curve was taken as the melting point. The starting point was taken as the pyrolysis point.

The composition of the copolymer was calculated based on the fluorine content and chlorine content of the copolymer. Here, the fluorine content is determined by trapping hydrogen fluoride generated by thermal decomposition of the copolymer in an aqueous solution, and using a fluoride ion selective electrode (No.
, 476042), and the chlorine content was determined by molding the copolymer into a sheet and using a fluorescent X-ray analyzer (Rigaku Denki!!).
21KF 3064 M type) was used for quantitative determination based on the peak height of the characteristic X-ray of chlorine.

East Millet Quantity 1 Measured according to JIS method 7201-1972 using Toyo Seiki candle method combustion tester No. 606.

Naoga jLi dust Measured based on ASTM D-790.

Example 1 The molar ratio of tetrafluoroethylene/chlorotrifluoroethylene/ethylene was 45/24/31, the melting point was 201°C, the thermal decomposition point was 367°C, and the oxygen index was 76.
Using an ethylene-tetrafluoroethylene-chlorotrifluoroethylene terpolymer with a volumetric flow rate of 90 mm'' and 7 seconds, it was heated at 220°C using a 20 mm single-screw extruder.
It was extruded into a 12 cm wide film (thickness 100 μm). The film thus obtained had good appearance and flexibility. The flexural modulus of the terpolymer at room temperature was 5.2 x 10'kg/cm". The tensile strength and elongation of the unstretched film were 2.6 k, respectively.
g/mm”.

405%, but by simultaneously biaxially stretching it at 60°C with 2 times the length and width, it became 4.2 kg/m.
m”, 310%.

Example 2 The molar ratio of tetrafluoroethylene/chlorotrifluoroethylene/ethylene was 33/36/31, the melting point was 72°C, the thermal decomposition point was 357°C1, and the oxygen index was 80.
Using an ethylene-tetrafluoroethylene-chlorotrifluoroethylene terpolymer with a volumetric flow rate of 80 mm/sec, 220
It was extruded at 12 cm into a 2 cm wide film (90 μm thick). The film thus obtained had good appearance and flexibility. Incidentally, the flexural modulus of the terpolymer at room temperature was 4.9×1G"kg/Cm". The tensile strength and elongation of the unstretched film are 2.8k, respectively.
g/mm”.

492%, but by simultaneously stretching the two wheels at 50°C with 2 times the length and width, each became 4.5 kg/m.
m”, 376%.

Comparative Example 1 The molar ratio of tetrafluoroethylene/chlorotrifluoroethylene/ethylene was 20/31/49, the melting point was 232°C, the thermal decomposition point was 313°C, and the volume flow rate was 85 m
20 mm using ethylene-tetrafluoroethylene-chlorotrifluoroethylene terpolymer with a+”7 seconds
A 12ci wide film (
It was extruded to a thickness of 100 μm. The film thus obtained had a good appearance, but had a low oxygen index of 45.
Also, the flexural modulus at room temperature is 9. OX 1G' kg/
cm” and was somewhat lacking in flexibility.

Comparative Example 2 Tetrafluoroethylene/ethylene content molar ratio is 52
/48, melting point is 270°C, thermal decomposition point is 345°C,
Using a copolymer with a volume flow rate of Hmm''/sec, 20 m
A 12 cm wide film (
It was extruded to a thickness of 75 μm. Although the film had a good appearance, it had a low oxygen index of 31 and a flexural modulus of 8.3 x 1 G'kg/cm'' at room temperature, which was somewhat lacking in flexibility.

Comparative Example 3 Melting point: 60°C, thermal decomposition point: 363°C, volumetric flow rate: 8
A similar test was conducted on polyvinylidene fluoride resin with a diameter of 37 mm. In this case, the oxygen index is low at 39,
Further, the bending elastic modulus was 1.3XIO'kg/cm'', which meant that it lacked flexibility.

Example 3 100 parts by weight of the same terpolymer powder as in Example 2 and 2
-(2'-Hydroxy-3''-butyl-5'-methylphenyl)-5-chlorobenzotriazole [ultraviolet absorber] and parts by weight were drive blended, and the width was 12 cm in the same manner as in Example 2. A film with a thickness of 75μ was obtained.

This film had a good appearance and excellent ultraviolet shielding properties.

Comparative Example 4 Using the same terpolymer as Comparative Example 2, the extrusion temperature was set to 30
An attempt was made to form a film in the same manner as in Example 3 except that the temperature was 0°C, but a film with extremely good bleed-out of the ultraviolet absorber could not be obtained.

[Effects of the Invention] The film of the present invention has flame retardancy with an oxygen index of 60 or more, and a flexural modulus of elasticity at room temperature of 6 x In3 kg/cm.
It has the following characteristics and excellent flexibility. In addition, the difference between the melting point and decomposition point of the copolymer used is as large as 120°C or more, and the melting point is relatively low, so it has excellent moldability and allows for smooth blending of various additive components, especially organic additive components. The effectiveness of implementation is recognized. Furthermore, it has the characteristic that mechanical properties can be easily improved by stretching.

In addition to the above properties, the film of the present invention has weather resistance, mold releasability,
Because of its excellent electrical properties, it is useful for solar films, marking films, release films, electrical insulation films, weather-resistant laminate films, etc.

Claims (1)

[Scope of Claims] 1) A copolymer of tetrafluoroethylene, chlorotrifluoroethylene, and ethylene, the copolymer composition of which is 10 to 60 mol% of tetrafluoroethylene, 20 to 60 mol% of chlorotrifluoroethylene, A flame-retardant resin film characterized in that it is formed by melt-molding a copolymer containing 20 to 40 mol% of ethylene alone or a mixture of the copolymer and an additive component. 2) The flame-retardant resin film according to claim 1, which uses a copolymer alone. 3) The flame-retardant resin film according to claim 1, which uses a mixture of a copolymer and an additive component. 4) Claim 3 in which the additional component is an ultraviolet absorber
Flame-retardant resin film described in Section 1. 5) The flame-retardant resin film according to claim 3, wherein the additive component is a pigment.