JPH10120738A - Production of fluorine-containing graft polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject polymer excellent in heat resistance and processability, useful for a corrosion-resistant member such as tube, etc., by radically copolymerizing a macromonomer with a specific monomer. SOLUTION: (A) A macromonomer containing a fluoroolefin unit, preferably a monomer shown by the formula (X, Y and Z are each H, F or Cl; R is H, methyl or ethyl; A is an unsaturated bond-containing group; (n) is a positive number) having 5,000-200,000 number-average molecular is radically copolymerized with (B) a fluoroolefin-containing monomer. Preferably, the fluoroolefin unit in the component A is one or more units selected from chlorotrifluoroethylene, tetrafluoroethylene, vinylidene fluoride and trifluoroethylene.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for corrosion-resistant members such as tubes, hoses and sheets, flexible fluororesins which can be molded at low temperatures such as wire coating materials and weather-resistant films, and fluororesins for highly weather-resistant paints. And a method for producing a graft polymer containing a fluoroolefin unit in a trunk component and a branch component.

[0002]

2. Description of the Related Art Polytetrafluoroethylene (PTF)
Fluororesins represented by E) have excellent heat resistance, chemical resistance, electrical insulation and lubricity, and are used in the fields of semiconductors, automobiles and industrial equipment. In recent years, there has been an increasing demand for soft fluororesins which can be easily molded, and fluorine-containing block polymers (JP-A-53-86788) and fluorine-containing graft polymers (JP-A-58-206615) have been proposed. . The fluorinated graft polymer is prepared by copolymerizing a fluoroolefin and a peroxide having an unsaturated group in a first step to produce a polymer peroxide containing a peroxy group in a side chain, and then converting the fluoroolefin to a polymer in a second step. It is produced by graft polymerization to peroxide, but unreacted peroxy groups remain in the graft polymer, and a fluoroolefin linear polymer is generated from radicals that are liberated when the peroxy group is cleaved. However, since a blend of the fluoroolefin linear polymer and the graft polymer is obtained, the resulting fluorine-containing graft polymer has a problem in heat resistance or processability, and has disadvantages such as coloring of a molded article.

[0003]

SUMMARY OF THE INVENTION The present invention provides a process for producing a fluorine-containing graft polymer having excellent heat resistance and processability.

[0004]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, they have obtained a radical copolymer of a monomer containing fluoroolefin with a macromonomer containing fluoroolefin unit. The inventors have found that the above-mentioned polymer solves the above-mentioned problems, and have accomplished the present invention.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION The macromonomer containing a fluoroolefin in the present invention constitutes a branch component (graft chain) of a graft polymer intended in the present invention, and is not particularly limited. The macromonomer represented by (1) is preferred. H (CFX-CYZ) _n CHRO-A (1) (wherein, X, Y and Z represent a hydrogen atom, a fluorine atom or a chlorine atom, R represents a hydrogen atom, a methyl group or an ethyl group, and A represents The macromonomer represented by the formula (1) has a number average molecular weight in terms of polystyrene of 500 to 200,000 as measured by gel permeation chromatography. If it is less than 500, the characteristics as a graft chain may not be exhibited, and if it exceeds 200,000, the polymerizability may be reduced.

The macromonomer is, for example, Poly
mer Bulletin 16 , 481-485 (1
986), and can be produced according to the production method described in
First, as a first step, as shown in the following formula (2), a macromonomer precursor having a hydroxyl group at a terminal by radical polymerization of a fluoroolefin using an alcohol as a chain transfer agent [hereinafter referred to as a “prepolymer”. ] To produce a fluorine-containing macromonomer by bonding an unsaturated group as shown in the following formula (3). nCFX = CYZ + RCH ₂ OH → H (CFX-CYZ) _n CHROH (2) H (CFX-CYZ) _n CHROH + AB → H (CFX-CYZ) _n CHRO-A + HB (3) (where X , Y and Z each represent a hydrogen atom, a fluorine atom or a chlorine atom, R represents a hydrogen atom, a methyl group or an ethyl group, A represents a group having an unsaturated bond, B reacts with a hydrogen atom and is eliminated. Represents a possible group, and n represents a positive number.)

The fluoroolefin used for producing the macromonomer includes tetrafluoroethylene,
Chlorotrifluoroethylene, trifluoroethylene,
Examples thereof include vinylidene fluoride, vinyl fluoride, and hexafluoropropylene, and one of tetrafluoroethylene, chlorotrifluoroethylene, trifluoroethylene, and vinylidene fluoride, in view of chain transferability and reaction yield of an alcohol described below, or It is desirable to use a combination of two or more fluoroolefins such as chlorotrifluoroethylene and vinylidene fluoride, tetrafluoroethylene and hexafluoropropylene, and vinylidene fluoride and hexafluoropropylene. Furthermore,
In order to improve moldability and reduce costs, a copolymerizable monomer may be used in combination. Such monomers include:
Examples include ethylene, propylene, isobutylene, vinyl chloride, vinylidene chloride, vinyl ethers, vinyl esters, and crotonic esters. In order not to impair the properties of the soft fluororesin, it is desirable to use the monomer in an amount equal to or less than the molar amount of the fluoroolefin.

The prepolymer represented by the formula (2) is
It is produced by subjecting the fluoroolefin to radical polymerization using an alcohol as a chain transfer agent in the presence of a radical generating initiator. Examples of the alcohol include methanol, ethanol, propanol, and isopropanol. Among them, methanol is preferable from the viewpoint of reactivity. Organic radicals such as tertiary butyl peroxide, diisopropyl peroxydicarbonate, dinormal propyl peroxydicarbonate, tertiary butyl peroxyhivarate and tertiary butyl peroxyisobutyrate as the radical generating initiator, Examples include azo compounds such as azobisisobutyronitrile and azobiscyclohexanecarbonitrile and inorganic peroxides such as ammonium persulfate.

The preferable temperature under the preferable conditions in the above polymerization is 20.degree. C. to 200.degree. C., and the preferable pressure is 3 to 10.
0 atm and a preferred reaction time is 1 to 24 hours.
Further, in order to prevent corrosion of the reactor, an acid remover such as potassium carbonate, 2-sodium phosphate, sodium hydrogen sulfate and sodium borate may be added.

[0010] Next, the macromonomer represented by the above formula (3) can be used in the presence of an organic solvent in the presence of the prepolymer obtained above and a polymer having a functional group reactive with a hydroxyl group in the prepolymer. It is produced by reacting a compound containing a saturated group. Examples of the unsaturated group-containing compound include (meth)
Examples include organic acids such as acrylic acid, vinyl acetic acid and vinyl nonanoic acid, chlorine-containing compounds such as (meth) acrylic acid chloride, allyl chloride, chloroethyl vinyl ether and vinyl chloroacetate, and vinyl acetate. In this case, the prepolymer is reacted by a dehydration esterification reaction, in the case of a dehydrochlorination reaction, and in the case of a deacetic acid reaction. Among these, the compounds are preferable from the viewpoint of ease of reaction. When these compounds are used, B in the formula (3) represents a hydroxyl group, a chlorine atom or an oxyacetyl group.

As the organic solvent, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate,
Examples include butyl acetate, toluene and xylene. It is preferable to promote the reaction by using organic or inorganic acids such as paratoluenesulfonic acid and sulfuric acid, amines such as triethylamine and quinoline, and inorganic bases such as sodium hydroxide. Under preferable reaction conditions, a suitable reaction temperature is 10 ° C to 100 ° C, and a preferable reaction time is 1 to 24 hours. Further, a polymerization inhibitor may be added to prevent polymerization of the unsaturated group-containing compound. Examples of the polymerization inhibitor include methoxyhydroquinone, hydroquinone, and phenothiazine.

In the present invention, the fluorine-containing macromonomer obtained above and a monomer containing a fluoroolefin are subjected to radical copolymerization, and the fluoroolefin polymer becomes a backbone component (backbone polymer chain). It is characterized by producing a graft polymer.

The fluoroolefin includes tetrafluoroethylene, chlorotrifluoroethylene, trifluoroethylene, vinylidene fluoride, vinyl fluoride,
Hexafluoropropylene and perfluoro (alkyl vinyl ether) are exemplified. Among these, one of tetrafluoroethylene, chlorotrifluoroethylene, trifluoroethylene, dichlorodifluoroethylene, vinylidene fluoride and vinyl fluoride, or tetrafluoroethylene and hexafluoropropylene, in view of copolymerizability with a macromonomer. It is desirable to use a combination of two or more fluoroolefins such as tetrafluoroethylene and perfluoro (alkyl vinyl ether), chlorotrifluoroethylene and vinylidene fluoride, and vinylidene fluoride and hexafluoropropylene.

Further, a copolymerizable monomer may be used in combination to increase heat resistance and reduce cost. Such monomers include ethylene, propylene, olefins such as isobutylene, vinyl chloride, chloroolefins such as vinylidene chloride, ethyl vinyl ether, butyl vinyl ether, vinyl ethers such as cyclohexyl vinyl ether, vinyl acetate, vinyl propionate,
Examples thereof include vinyl esters such as vinyl pivalate, vinyl caproate, vinyl versatate and vinyl cyclohexanecarboxylate, and crotonic esters such as methyl crotonate, ethyl crotonate and cyclohexyl crotonate. Further, a hydroxyl group-containing monomer such as hydroxybutyl vinyl ether, an epoxy group-containing monomer such as glycidyl vinyl ether and allyl glycidyl ether, and a carboxylic acid-containing monomer such as acrylic acid may be copolymerized in order to impart crosslinkability. In order not to impair the properties of the soft fluororesin, it is desirable to use these monomers in an amount equal to or less than the molar amount of the fluoroolefin.

The reaction for producing the fluorine-containing graft polymer is a reaction in which the monomer containing the fluoroolefin is radically copolymerized with the macromonomer in the presence of a radical-generating polymerization initiator. As the polymerization method, suspension polymerization and emulsion polymerization in an aqueous medium, solution polymerization in an organic solvent, and the like can be adopted. As the organic solvent, organic hydrocarbon compounds and fluorine organic solvents are suitable, and cyclic ethers such as tetrahydrofuran and dioxane; aromatic hydrocarbon compounds such as benzene, toluene and xylene; esters such as ethyl acetate and butyl acetate And ketones such as acetone, methyl ethyl ketone and cyclohexanone; and freons such as octafluorocyclobutane. One or more of these can be used. Further, water and an organic solvent may be used in combination.

The radical-generating polymerization initiator includes:
Organic peroxides such as diisopropylperoxydicarbonate, tert-butylperoxypivalate, benzoyl peroxide and lauroyl peroxide, azo compounds such as azobisisobutyronitrile and azobisisovaleronitrile, ammonium persulfate and potassium persulfate And other inorganic peroxides can be used. The amount of these used is preferably 0.001 to 10 parts by weight based on 100 parts by weight of all monomers. Examples of the emulsifier in the case of emulsion polymerization include potassium or ammonium perfluorooctanoic acid, ammonium perfluorooctanesulfonate, sodium salt of higher alcohol sulfate and polyethylene glycol ether.

In the case of suspension polymerization, an appropriate amount of a suspension stabilizer may be used. Examples of such suspension stabilizers include methylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose and polyvinyl alcohol. The preferred temperature under the preferred polymerization conditions is 2
0-100 ° C., the preferred pressure is 1-200 atm and the preferred polymerization time is 3-40 hours. PH if necessary
Potassium carbonate, sodium hydrogen carbonate, hydrotalcite, an anion exchange resin and the like may be added as a regulator.

The preferred graft polymer obtained by the production method of the present invention has both properties of a resin and an elastomer. When the graft chain (macromonomer segment) has an elastomeric property, the trunk polymer chain has a resin-like property. In the case where the graft chains have properties and the graft chains have resin properties, on the other hand, those in which the backbone polymer chains have elastomer properties are preferred. In the present invention, the elastomeric property means that the segment has little or no melting point, has a glass transition temperature (Tg) of room temperature or lower, and is in a raw rubber state. The term “resin-like property” means that the segment has a melting point or Tg higher than room temperature and is solid.

The graft chain having elastomeric properties is obtained by copolymerizing chlorotrifluoroethylene / vinylidene fluoride at a weight ratio of 80 to 40/20 to 60 as the fluoroolefin contained in the macromonomer. In addition, those obtained by copolymerizing vinylidene fluoride / hexafluoropropylene in a weight ratio of 55 to 30/45 to 70 are exemplified, and the case of chlorotrifluoroethylene / vinylidene fluoride is preferable.

Further, as the backbone polymer chain having appropriate resin properties, chlorotrifluoroethylene, vinylidene fluoride and chlorotrifluoroethylene / vinylidene fluoride as fluoroolefins to be copolymerized with the macromonomer are 5 to 40. / 95-60 or 97-8
It is preferably from 0/3 to 20 (weight ratio).

The composition of the fluorine-containing graft polymer in the present invention is preferably such that the ratio of fluoroolefin / macromonomer / other monomer is 25 to 95/5 to 50/0 to 50 (weight ratio), and gel permeation chromatography It is preferable that the number average molecular weight in terms of polystyrene measured in the above is 5,000 to 1,000,000.
When a fluorinated graft polymer is used as a weather-resistant paint substrate, it is desirable that the graft polymer be soluble in an organic solvent.

The fluorinated graft polymer obtained by the production method of the present invention has thermoplasticity and can be used alone after being molded, and can be mixed with a film material and a carbon fiber combined with a glass cloth and a polyester fiber. It can be used for composite materials that have been made. Further, it can be dissolved in an organic solvent and used as a weather-resistant paint.
Examples of such organic solvents include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, esters such as ethyl acetate and butyl acetate, amides such as dimethylformamide, and aromatics such as toluene and xylene.
When a crosslinkable monomer is copolymerized, crosslinking may be performed by using a curing agent such as polyisocyanate and melamine in combination.

[0023]

The present invention will be specifically described below with reference to examples.

Example 1 (Synthesis of prepolymer) 400 g of methanol and 30 g of dinormal propyl peroxydicarbonate were charged into a 2-liter autoclave equipped with a stirrer, and degassing was performed by repeating degassing and nitrogen replacement three times. Chlorotrifluoroethylene [hereinafter referred to as “CTFE”. 400 g and vinylidene fluoride [hereinafter referred to as "VdF". ] To 110
g. When the temperature was raised to 40 ° C. and the reaction was performed for 24 hours, the pressure dropped from 25 atm to 20 atm. After purging the residual pressure, the autoclave was opened.
After methanol was distilled off, the mixture was precipitated in hexane to obtain 412 g of a translucent rubbery prepolymer. Infrared absorption spectrum of the obtained prepolymer [hereinafter, referred to as “IR”]
Results of measurement of a peak of C-H was observed in the vicinity of ^-1 peak and 3000cm of OH in the vicinity of 3450 cm ^-1. As a result of composition analysis, the fluorine content was 50%, the chlorine content was 23%, and the weight ratio of CTFE / VdF was 78/22.
(Hereinafter, all compositions represent weight ratios). Furthermore, gel permeation chromatography
[Hereafter referred to as “GPC”. ], The number average molecular weight in terms of polystyrene [hereinafter referred to as “Mn”]. ]
Is 4800 and weight average molecular weight [hereinafter referred to as “Mw”. ] Was 6,600. As a result of DSC measurement, no melting point was observed above room temperature.

(Synthesis of Macromonomer) 200 g of the prepolymer obtained above and 200 g of ethyl acetate were charged into a 1-liter flask equipped with a stirrer, a dropping funnel, and a thermometer to form a homogeneous solution. 0.5 g of hydroquinone was added and heated to 40 ° C. Then 8.6 g of acrylic acid chloride and ethyl acetate 4
0 g of the mixed solution was dropped from the dropping funnel over 10 minutes. After reacting for 4 hours and cooling to room temperature, butyl acetate was distilled off, followed by washing with a large amount of water to remove excess acrylic acid chloride and triethylamine. Drying at 50 ° C. yielded 182 g of macromonomer. The macromonomer result of an IR measurement of the peak of the C = C was observed in the peak and 1650cm around ^-1 C = O near 1750 cm ^-1, a peak attributed to OH was almost disappeared.

(Synthesis of Graft Polymer) In a 1-liter autoclave equipped with a stirrer, 300 g of water, 100 g of ethyl acetate, 0.7 g of hydroxypropyl methylcellulose [Metroose 60SH50: manufactured by Shin-Etsu Chemical Co., Ltd.],
2 g of diisopropyl peroxydicarbonate and 20 g of the macromonomer obtained above were charged, and after degassing and nitrogen purging were repeated three times and then degassed, 60 g of VdF was charged.
The temperature was raised to 35 ° C. to initiate polymerization. After 24 hours, the reaction was terminated, the residual pressure was purged, and water washing was repeated three times.
It was dried at 00 ° C. to obtain 65 g of a white solid polymer.
When the DSC of this polymer was measured, it was found to be 150 to 16
A melting point peak was observed at 0 ° C. Extraction with ethyl acetate using a Soxhlet extractor revealed that the insoluble matter was 98%, and a peak of C ＝ O attributed to the macromonomer was observed in IR. The chlorine analysis value was 7.2%, and VdF
The ratio of / macromonomer was confirmed to be 70/30. As a result of GPC, Mn =
78000, Mw = 161,000.

Examples 2 to 3 Copolymerization was carried out in the same manner as in Example 1 except that the monomers were changed as shown in Table 1, to obtain a graft polymer.

Example 4 In a 1 liter autoclave equipped with a stirrer, 290 g of ethyl acetate and a macromonomer (prepolymer composition CTF
E / VdF = 25/75, Mn = 12900, Mw = 1
8000; reactive group CH ₂ = CHCOO-) 50g, 2- hydroxyethyl crotonate (hereinafter referred to as "HECR"].
25.2 g, vinyl pivalate 80 g [hereinafter referred to as “VP”
v ". ], And degassing and nitrogen replacement were repeated three times, followed by degassing, and 150 g of CTFE was charged. After the temperature was raised to 64 ° C., 3.75 g of azobisisobutyronitrile was injected under pressure to start polymerization. Thereafter, polymerization was carried out for 14 hours, unreacted CTFE was purged, and the autoclave was opened to obtain a copolymer solution. The obtained solution was poured into hexane, washed and dried to obtain 190 g of a copolymer. As a result of measuring the obtained copolymer by GPC, Mn = 12600, M
w = 26,800. The glass transition temperature observed above room temperature was 58 ° C. The hydroxyl value of this copolymer was 45 (mg-KOH / g-resin), and the composition of the copolymer was CTFE / macromonomer / VPv / HECR.
= 33/21/36/10. This copolymer was dissolved in a MEK / cyclohexanone solvent to a solid content of 50% to obtain a colorless and transparent solution.

[0029]

[Table 1]

Test Examples 1 to 3 and Comparative Test Examples 1 to 2 The fluorine-containing graft polymer obtained in Examples 1 to 3 was press-molded (at a temperature of 210 ° C.) to produce a sheet having a thickness of 1 mm. The elongation was measured. Similarly, a sheet having a thickness of 3 mm was prepared, and the coloring was visually evaluated, and the Shore D hardness was measured in accordance with ASTM-D1484. Table 2 shows the results. As Comparative Test Examples 1 and 2, a test similar to Test Example 1 was performed using a commercially available PCTFE sheet and Cefralsoft G150 (fluorine-containing graft polymer manufactured by Central Glass Co., Ltd.), and the results are shown in Table 2.

[0031]

[Table 2]

Test Example 4 Takenate D177N (a polyisocyanate manufactured by Takeda Pharmaceutical Co., Ltd.) was mixed with the solution obtained in Example 4 so that hydroxyl group / isocyanate = 1/1 (equivalent), and chromate-treated aluminum The plate was coated with an applicator to a film thickness of 35 μm. After drying at room temperature for one week, Dew Cycle Sunshine Weather Meter [Suga Test Instruments Co., Ltd.
), An accelerated weather resistance test was conducted at a black panel temperature of 63 ° C and a cycle of irradiation of 60 minutes / darkness of 60 minutes, and the gloss retention at 60 ° C after the test for 500 hours was as good as 80%. .

Comparative Test Example 3 CTFE / cyclohexyl vinyl ether / ethyl vinyl ether / hydroxybutyl vinyl ether = 50/3
As a result of preparing a copolymer having a composition of 0/10/10 and Mn = 12800 in the same manner and conducting an accelerated weather resistance test,
The gloss retention at 60 ° C. after 500 hours was 55%, indicating that there was a problem in weather resistance.

[0034]

The fluorine-containing graft polymer obtained by the production method of the present invention is excellent in workability due to large elongation, and is excellent in heat resistance, so that it is not colored even when molded, and the appearance of the molded article is excellent. Is useful as a soft fluororesin. Further, if the fluorine-containing graft polymer obtained by the production method of the present invention is dissolved in an organic solvent and used as a coating, a coating film having high weather resistance can be obtained.

Claims (4)

[Claims] 1. A process for producing a fluorine-containing graft polymer, comprising subjecting a macromonomer containing a fluoroolefin unit and a monomer containing a fluoroolefin to radical copolymerization. 2. The macromonomer is represented by the following formula (1):
The method for producing a fluorine-containing graft polymer according to claim 1, wherein the number average molecular weight is from 500 to 200,000. H (CFX-CYZ) _n CHRO-A (1) (wherein, X, Y and Z represent a hydrogen atom, a fluorine atom or a chlorine atom, R represents a hydrogen atom, a methyl group or an ethyl group, and A represents It represents a group containing a saturated bond, and n represents a positive number.) 3. The fluorine-containing unit according to claim 1, wherein the fluoroolefin unit in the macromonomer is at least one unit selected from chlorotrifluoroethylene, tetrafluoroethylene, vinylidene fluoride and trifluoroethylene. A method for producing a graft polymer. 4. The fluoroolefin to be radically copolymerized with the macromonomer is at least one selected from chlorofluoroethylene, tetrafluoroethylene, vinylidene fluoride, trifluoroethylene, hexafluoropropylene and perfluoroalkoxyvinyl ether. A method for producing the fluorine-containing graft polymer according to any one of claims 1 to 3.