JPS60203613A - Fluorine-containing copolymer - Google Patents

Abstract

PURPOSE:To fluorine-containing copolymer, consisting of tetrafluoroethylene units, vinylidene fluoride units and hexafluoropropylene units respectively in specific amounts, having improved chemical resistance, and moldable at low temperatures. CONSTITUTION:A ternary copolymer, obtained by copolymerizing a monomeric mixture of (A) 40-49wt% tetrafluoroethylene units with (B) <=29wt% vinylidene fluoride units and (C) <=40wt% hexafluoropropylene units in amounts to give 60-51wt% total component (B) and (C), and having preferably 0.5-15 melt index. EFFECT:Mechanical characteristics, e.g. tensile strength, elongation, etc. of the above-mentioned copolymer are improved by vulcanization.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a fluorine-containing copolymer, more specifically, tJf
The present invention relates to a terpolymer consisting of tetrafluoroethylene units, vinylidene fluoride units, and hexafluoropropylene units, which has excellent chemical resistance and can be molded at low temperatures.

Fluorine-containing polymers have excellent heat resistance, chemical resistance, electrical insulation, etc., and also have unique non-adhesion and low friction properties, so they are used in the chemical industry, electrical/electronic industry, and machinery. Not only industry but also space development.

It is used in a wide range of fields such as the aircraft industry and the cryogenic industry.

By the way, polytetrafluoroethylene, which is typical among such fluorine-containing polymers, has excellent heat resistance, chemical resistance, mechanical properties, electrical properties, etc., as well as low friction and non-stick properties. However, due to its high melting point and melt viscosity, it has the disadvantage that ordinary molding methods cannot be applied to it.

Therefore, many attempts have been made to obtain a fluorine-containing polymer that has as many of the excellent properties of polytetrafluoroethylene as possible, can be molded relatively easily, and is lubricant. For example, a copolymer of tetrafluoroethylene and hexafluoropropylene (Teflon IP; a registered trademark manufactured by DuPont), a copolymer of tetrafluoroethylene tohalf fluoroalkyl vinyl ether (Teflon PFA; a registered trademark manufactured by DuPont), Copolymers of ethylene, hexafluoropropylene and hibarfluoroalkyl vinyl ethyl (Teflon EPE; registered trademark manufactured by DuPont), copolymers of tetrafluoroethylene and ethylene (
Tefzel (manufactured by DuPont, a registered commercial company) has been developed and used as an upper mold. However, although these copolymers have excellent chemical resistance and can be melt-molded, they have a high melting point of about 250° C. or higher, so it is necessary to use special processing equipment.

1. Polyvinylidene fluoride is also used as an upper mold,
Although this material has a low melting point of about 180° C. and can be molded using ordinary processing equipment, it has the disadvantage that its chemical resistance is inferior to that of the polytetrafluoroethylene-based material described above.

In addition to these, terpolymers of tetrafluoroethylene, vinylidene fluoride and hexafluoropropylene are also known. For example, 3 to 35 tetrafluoroethylene units
97 to 65 vinylidene fluoride units and hexafluoropropylene units, and the weight ratio of vinylidene fluoride units to hexafluoropropylene units is 2.33:1 to 0.667. A ternary copolymer (Japanese Patent Publication No. 1983-3495) in which the molar ratio of tetrafluoroethylene:vinyriteneflora-1 and hexafluoropropylene is 5:85.7:
9.3.5.

59', 7: 35.3, 30:28:42 and 30
Copolymer divided into four values of 5416 (Special Publication No. 51
-8432 Publication), consisting of 10 to 30 units by weight of vinyl fluoroethylene units, 1 unit of vinylidenefluoride and 1 unit of hexafluoropropylene by weight, and 1 unit of vinylidenefluoride by weight. A method for producing a terpolymer in which hexafluoropropylene units have a weight ratio of 1.6°1 to 4°1 (Japanese Patent Publication No. 18957/1981), a borrowed fluoroethylene unit having a weight ratio of 12 to 48,
30.~81 nylidene fluoride units by weight and 7
~ Consists of 24 hexafluoropropylene units,
If the amount of tetrafluoroethylene is less than 42 times by weight, a terpolymer having less than 15 times more than hexafluoropropylene units (JP-A-57-98514, Publication No. 9)
etc. are known. However, although these terpolymers can all be molded at low temperatures, they are not necessarily satisfactory in surface J chemical properties.

Furthermore, a terpolymer consisting of 50-85% by weight of borrowed fluoroethylene units, 10.-45% by weight of borrowed niritin fluoride units, and 5-40% by weight of borrowed safluoropropylene units has been proposed. (Unexamined Japanese Patent Publication No. 52-2208
Publication No. 4). However, although this terpolymer has excellent chemical resistance, it has a problem of poor moldability at low temperatures.

As described above, among the conventionally known fluorine-containing polymers, there is no one that satisfies both chemical resistance and moldability at low temperatures, and the industry is currently trying to develop a fluorine-containing polymer that can satisfy both of these requirements. It was strongly requested.

In addition, in the present invention, a polymer with excellent moldability at low temperatures refers to a polymer that can be molded at a temperature at which steam can be used as a heat source for molding, i.e., 180°C or lower, preferably 150°C or lower. It refers to a water-retaining polymer.

In response to these demands, the present inventors conducted intensive research to provide a fluorine-containing polymer that has excellent chemical resistance and moldability at low temperatures. A terpolymer containing a specific ratio of vinylidene fluoride (hereinafter abbreviated as TFE) units, vinylidene fluoride (hereinafter abbreviated as VdF) units, and hexa70ropropylene (hereinafter abbreviated as RFP) units is suitable for this purpose. The present invention was completed based on this finding.

In other words, the present invention provides ``[''FE unit unit 4th to 49th The present invention provides a fluorine-containing copolymer comprising the above.

The content of TFE units in the copolymer of the present invention is from 40 to
It is necessary to be within the range of 49 weight section.

If this amount exceeds 40% by weight, chemical resistance will be poor, while if it exceeds 49% by weight, moldability at low temperatures will deteriorate.

Further, the content of VdF units is 29% by weight or less, and if this amount exceeds 29% by weight, the 1st phase chemical resistance deteriorates. Furthermore, it is necessary that the HF' and P units be under a 40% weight setting, and if this amount exceeds 40% by weight, polymerization will be difficult, the degree of polymerization will be small, and the mechanical properties will be poor.

By the way, the temperature of the copolymer is 180°C or lower, preferably 15°C.
In order to be moldable at a low temperature of 0°C or lower, the melt viscosity is important, and the melt index (hereinafter abbreviated as MI) at a temperature of 180°C is 0.1 to 50, preferably 0.5 to 50. It is desirable that it be within the range of 15.

If the number of 54 pieces is less than 0.1, the moldability is poor, and the number of 54 pieces is less than 0.1.
If it exceeds 0, the moldability is poor and the mechanical strength is poor.

The above M has a strong correlation with the molecular weight, and in general, the smaller the molecular weight, the smaller the M, and the larger the molecular weight, the smaller the MI. Molecular weight also affects chemical resistance, and when comparing copolymers with the same composition, the larger the molecular weight, the better the chemical resistance.

Various methods can be used to adjust the molecular weight, but it is preferably carried out by increasing or decreasing the amount of chain transfer agent added during the polymerization reaction of the copolymer.

The fluorine-containing copolymer of the present invention can be obtained by copolymerizing a monomer mixture in an aqueous or non-aqueous medium using a polymerization initiator and a chain transfer agent.

Copolymerization is usually carried out in a pressure-resistant reaction vessel, and the polymerization conditions are appropriately selected depending on the type and amount of the polymerization initiator and medium used, but usually the temperature is 0 to 130°C and the polymerization pressure is i -
100K9/cn! -G.

The non-aqueous medium is preferably an organic solvent that does not have C--H bonds that would inhibit chain transfer, such as perfluorocyclobutane, perfluorodimethylcyclobutane, perfluorocarbons such as perfluorokerosenate, 1,1. 2
-) dichloro-1,212-trifluoroethane, 1.゛2-Dichloro 1.1,2. ．． Chlorofluorocarbons such as 2-tetrafluoroethane, trichlorofluoromethane, and dichlorofluoromethane are suitable. Among these, especially 1,1゜2-1-licro 1kor 1.2.2
4 refluoroethylene tanker is economical and preferred.

As the polymerization initiator, when the polymerization is carried out in an aqueous medium, water-soluble inorganic peroxides such as ammonia, potassium, and sodium salts such as persulfuric acid, perphosphoric acid, and perboric acid, or hydrogen peroxide are used.

These peroxides contain reducing agents such as sulfite, hypomyelite,
It can be used in combination with ammonia, potassium, sodium salts, etc. of metasulfite, thiosulfite, phosphorous acid, hydrophosphorous acid, etc.

Also polymerizations carried out in non-aqueous media, oil-soluble peroxides such as diisopropyl peroxydicarbonate, di-n-
Dialkyl peroxy/dicarbonates such as propyl peroxydicarbonate, t-butyl peroxyisobutyrate, 1. ~ Peroxy esters such as butyl peroxypiparate, diasilver oxides such as propionyl peroxide, di(perfluoropropionyl) peroxide, di(perfluorobutyryl)
Suitable examples include peroxide, di(perfluoroanthyl)peroxides such as di(trichlorooctafluorohexanoyl)peroxide, and di(chlorofluoroanthyl)peroxides. It is preferable to use these polymerization initiators in a range of 101 to 1 weight range based on the polymerization medium.

Furthermore, a chain transfer agent can be used for the purpose of controlling the molecular weight. Examples of chain transfer agents include isoparaffins such as inbencune and inhexane, alcohols such as methanol and ethanol, halides such as chloroform, carbons such as acetone, mercaptafs, dimethyl malonate, and succinic acid. Esters such as dimethyl ester are used. These chain transfer agents are preferably used in an amount of 10 or less by weight relative to the polymerization initiator.

Further, when copolymerization is carried out in an aqueous medium, it is desirable to carry out emulsion polymerization using an emulsifier of preferably 0.1 weight 1 or less in the aqueous medium, for the purpose of preventing polymer adhesion to the polymerization tank. As the emulsifier, salts such as fluorine-containing carboxylic acids and fluorine-containing sulfonic acids are preferable, and ammonium perfluorooctanoate is suitable, for example. However, an emulsifier is not always necessary.

As described above, when copolymerization is carried out in an aqueous medium, a method of adding an electrolyte such as magnesium chloride or a freezing method is used to separate the copolymer produced from the polymerization solution.

The fluorine-containing copolymer of the present invention has characteristics such as not dissolving in a dimethylformamide-tetrahydrofuran mixture, high chemical resistance, and excellent moldability at low temperatures. This vulcanization method improves mechanical properties such as tensile strength and elongation, and further improves chemical resistance1. Methods used for vulcanization of fluoroelastomers, such as peroxide vulcanization using organic peroxides, amine vulcanization using polyamine compounds, and polyol vulcanization using polyhydroxy compounds, can be used. . In the peroxide vulcanization method, a fluorine-containing copolymer is mixed with an organic peroxide, a co-vulcanizing agent, and if necessary a vulcanization aid or filler, etc., and then kneaded and then heated and cured. Sulfurize.

In the polyamine additive method, a fluorine-containing copolymer is mixed with an acid acceptor, a polyamine or a salt compound thereof, and if necessary, a filler, etc., and then kneaded and then heated and vulcanized.

In addition, in the polyol vulcanization method, the fluorine-containing copolymer is mixed with an acid acceptor, a polyhydroxy compound, a vulcanization accelerator, and a filler if necessary, and then heated and vulcanized. .

The above-mentioned organic peroxide is preferably one that easily generates peroxy radicals by heat, for example, 2.5
-dimethyl-2,5-di(t-butylperoxy)hexane-3,2,5-dimethyl-2,5-di(t-butylperoxy)hexane, etc. are suitable, and the preferable amount used is Per 100 parts by weight of fluorine-containing copolymer, 0.
It is selected in a range of 5 to 10 parts by weight. As a co-vulcanizing agent,
For example, triallylcyanurate, triallylisocyanurate, tris(diallylamine)'-8-)riazine, etc. are suitable, and these
It is preferably used in an amount of 0.5 to 10 parts by weight per part by weight. As the vulcanization aid and acid acceptor, divalent metal oxides or hydroxides, such as oxides or hydroxides of magnesium, calcium, zinc, lead, etc., are preferable, and if necessary, these fluorine-containing oxides or hydroxides are preferable. It is preferable to use the filler in an amount of 1 to 30 parts by weight per 100 parts by weight of the copolymer. Examples of the filler include carbon black, white carbon, silica, clay, and talc, as appropriate. Also, plasticizers and colorants can be used as necessary.

Suitable examples of the polyamine or its salt compound include trimethylene diamine, cinnamilitent trimethylene diamine, cinnamylidene ethylene diamine, N,N'-cinnamylidene-1,6-hexamethylene diamine, hexamethylene diamine carbamate, etc. These are used in a range of 11 to 5 parts per 100 parts by weight of the fluorine-containing copolymer.

Examples of polyhydroxy compounds include di-droquinone, 2,2-bis(4-hydroxychenyl)furopane, and 2,2-bis(4-hydroxyphenyl).
Perfluoropropane (bisphenyl AF), 4,4'-
Dihydroxydiphenyl ether, 4',4'-dihydroxydiphenylmethane, 2,2-bis(4-hydroxyphenyl)butane, etc. are suitable, and these may be used in an amount of 0.00% per ioo parts by weight of the fluorine-containing copolymer. It is preferable to use it in a range of 5 to 5 parts by weight. Suitable examples of vulcanization acceleration %1 include quaternary onium chlorides such as tetramethylammonium chloride, tetrabutylammonium chloride, tetrabutylammonium bromide, tetrabutylphosphonium chloride, benzyltriphenylphosphonium chloride, and the like. The fluorine-containing copolymer 1007j (per sentencing, preferably /d
' (Used in a range of 1, 2 to 10 parts by weight.

Methods for blending these vulcanizing agents, acid acceptors, fillers, etc. include the usual blending method for fluorine gastomers;
For example, a method of kneading between a pair of rubber wheels can be used. The compound thus obtained was placed in a mold at a temperature of 100 to 200°C for 10 to 6
Primary vulcanization is carried out by applying pressure for 0 minutes, and then vulcanization is carried out in a heating furnace for 1
By performing secondary vulcanization at a temperature of 50 to 300°C for 10 to 40 hours, a vulcanized product of the fluorine-containing copolymer is obtained.

The fluorine-containing copolymer of the present invention has the characteristics of both excellent chemical resistance and moldability at low temperatures, and when vulcanized, mechanical properties such as tensile strength and elongation can be improved. It also has the W characteristic that chemical resistance is further improved.

Next, the present invention will be explained in further detail with reference to Example V.

In addition, the composition of the copolymer in the example, MI, and each physical property before and after the application of voltage were determined as follows.

(1) Composition of the copolymer The composition of the copolymer was determined from the amount of gaseous monomer supplied, the amount of unreacted gas after completion of polymerization as analyzed by gas chromatography/F-, and its composition.

(2) Using λ1 Kou Toyo Seiki's melt indexer, temperature 180
℃, a load N of 2160 W is applied to an orifice with a nozzle diameter of 2.09 x m and a length of 8 mm, and the weight (2) extruded in −Cio minutes is calculated, and the value is defined as MI.

(3) Chemical resistance Cut a 5 cm x 1 nn rectangular sample from a 50 μm thick sheet, immerse it in methyl ethyl ketone and methanol at 60°C for 100 hours, and measure the weight change ('%) before and after immersion. Ta.

(4) Machine object A No. 3 dumbbell-shaped test piece was punched out from a sheet with a thickness of 2 mm, and measured according to JIS-K 6301 using a tensile tester (manufactured by Toyo Seiki 9) at a tensile speed of 50 cm and 1 minute.

Further, vulcanization of the fluorine-containing radical polymer was performed using the following conditions.

Mixed wire Roll primary press vulcanization 200℃ x 30 minutes Secondary heating furnace @ 220℃ x 14 hours Example 1 Deionized water ts was placed in a SUS autoclave with an internal volume of 3 tons.
oOy, ammonium perfluorooctanoate 4.5
f and 0: Add diethyl malonate 152 and replace with internal fN2 gas three times while stirring, then VdF/H
Mixed gas of FP/TFE (ratio is 1.5./85.5
/ 13. After replacing the mixture three times with Oi amount %), the temperature was adjusted to 80° C., and the pressure was increased to 8 to 9/C#iG' with the mixed gas.

Next, a solution of 3.07 ml of ammonium persulfate dissolved in 201 ml of deionized water was injected under pressure. Polymerization started immediately and a pressure drop occurred. When the internal pressure drops to 7 K9/ca G, VdF/HFP/TFE (22/33/45 wt%
) while repeating the operation of repressurizing to 8 Ky/cnl G with a mixed gas of 7 to 8 Ky/etda
Polymerization was continued at a pressure of 2 hours. After the polymerization reaction was completed, a 5% aqueous magnesium chloride solution was added to the emulsion polymerization solution while stirring, and the resulting copolymer was precipitated and filtered.
It was thoroughly washed with water and dried under reduced pressure at 100°C for a day and a night.

The composition of the obtained copolymer is VdF/HFP/TFE:
22.3/32.2/45.5% by weight, MI (180°C
) was 2.1. Table 1 shows the chemical resistance and mechanical properties before and after vulcanization.

Table 1 Judgment of chemical resistance is good if the increase/decrease is ±5% or more U'9.
This is for cases where the value is between ±5% and ±1o, and for cases where the value exceeds ±10%. As can be seen from this table, the chemical resistance of the obtained fluorine-containing copolymer is good, and the chemical resistance is improved by vulcanization. In addition, the mechanical properties are improved due to vulcanization.

Example 2 Initial mixed gas composition: VdF/HFP/TFE: 2
．． 6/ 82.4 / 15.0 wt%, additional mixed gas composition total VdF/HFP/TFE: 27/
25. / 48% by weight, but in the same manner as in Example.

The composition of the obtained copolymer was VdF/HFP/TFE2
7.3/24.5/48.2% by weight, MI(1
, 80°C) was (), 8. Table 2 shows the chemical resistance and mechanical properties before and after vulcanization.

Table 2 As can be seen from this table, the chemical resistance of the obtained copolymer is good. In addition, surface J chemical properties and mechanical properties Q are vulcanized (improved by 17%).

Comparative example” Mixed gas composition Total VdF / HTi”P / TFE
: 20.5, /30, /49.5% by weight.

The composition of the obtained copolymer 7 is VdF/IFF/Tl:
25,/16,159 weight mooring type. MI (180℃
) is 0, and moldability at low temperatures is poor.

Comparative Example 2 11-hair mixture gas composition VdF/H[i'P/TFE:
Change the weight ratio to 15/457/40 and set the polymerization time to 20
The flt change to time was performed in the same manner as in Example 1. The polymerization rate is very low and the amount of copolymer obtained is 5% of Example 1.
It was below. 50% tensile stress (110
Kg/crl, tensile strength is 30 K9/cn
1, and the mechanical properties are poor.

Comparative Example 3 Mixed gas composition: vaF/nFp/Twg: 28/
The same procedure as Example J was carried out except that the weight ratio was changed to 30/42.

The composition of the product is VdF/HFP/TFE: 34/
21/45 It was the weight clerk.

The surface 1 chemical resistance of this product was -10.5% for methyl ethyl ketone and -9.6% for methanol, and its chemical resistance was poor.

Patent applicant: Asahi Kasei Industries, Ltd. Agent Akira Agata

Claims (1)

[Claims] ] Tetrafluoroethylene units are 40 to 49 weight units, vinylitine fluoride units are 29 weight units or less, hexafluoropropylene units are 40 weight units or less, and the total of both is 60 to 5.
A fluorine-containing copolymer consisting of a single polymer.