JP2881837B2 - Fluorine-containing copolymer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fluorinated copolymer which gives a fluororesin having a high elastic modulus.

[Prior Art] Fluororesins are used in various fields due to their excellent heat resistance, chemical resistance and surface properties, but one of their drawbacks is that they have low elastic modulus. Another drawback is that a fluororesin other than polytetrafluoroethylene (PTFE) flows when heated above its melting point and cannot maintain its shape. PTFE does not flow even when heated above its melting point, but has the disadvantage that it cannot be melt molded. Thus, it has been desired to develop a fluororesin which can be melt-molded with a high elastic modulus and does not flow even when heated above its melting point.

It is considered that these required properties are satisfied by cross-linking a fluororesin after molding, and various cross-linking methods have been proposed so far.

For example, in JP-B-62-23772, a fluorine resin is cross-linked by irradiating an electron beam. However, this method is effective for hydrocarbon resins but cannot be applied to perfluoro resins.

In JP-A-61-155410, electron beam crosslinking is performed by adding a crosslinking agent such as triallyl cyanurate to a fluororesin. However, the resin obtained by this method is inferior in chemical resistance and heat resistance due to the presence of the crosslinking agent.

In JP-A-63-68604 and US Pat. No. 4,204,927, photocrosslinking is performed by adding a photoreactive group to a fluororesin. However, the resins obtained by these methods are inferior in chemical resistance and heat resistance.

Japanese Patent Publication No. 55-23567 describes that a copolymer of tetrafluoroethylene and perfluoroacrylic acid (derivative) is cross-linked by applying heat. However, there is no detailed description of the physical properties of the crosslinked polymer.

[Problems to be Solved by the Invention] An object of the present invention is to provide a fluorine-containing copolymer which gives a highly elastic fluororesin which has not been known hitherto.

Means for Solving the Problems The present invention has been made to solve the above-mentioned problems, and is a copolymer of the following compound (A) and the following compound (B). 80 to 99.9 mol% based polymerized units,
Provided is a fluorinated copolymer containing 0.1 to 20 mol% of a polymerized unit based on (B) and having a melt flow rate of 0.01 to 100.

(A) CF ₂ CCFX (X is F or Cl) (B) CF ₂ CCFOR ^f CH ₂ OH (R ^f is a perfluoroalkylene group or a perfluoroalkylene group containing an ether bond) A copolymer of the following compound (A), the following compound (B), and the following compound (C);
70 to 99.9 mol% of the polymerized unit based on (B), 0.1 to 20 mol% of the polymerized unit based on (B), and 10
Provided is a fluorine-containing copolymer, which is contained in an amount of 0.01 mol% or less and has a melt flow rate of 0.01 to 100.

(A) CF ₂ CCFX (X is F or Cl) (B) CF ₂ CCFOR ^f CH ₂ OH (R ^f is a perfluoroalkylene group or a perfluoroalkylene group containing an ether bond) (C) CF ₂ ＝ CFY (Y is a perfluoroalkyl group or a perfluoroalkoxy group) In this specification, a melt flow rate is an extrusion rate (g / g) measured at a temperature equal to or higher than the melting point of the fluorocopolymer.
Min), which was specifically measured by the following method.

Using a melt indexer, fluorinated copolymer
After loading into a 9.5 mm cylinder and holding at a temperature 30 ° C. higher than the melting point of the polymer for 5 minutes, the mixture was extruded at that temperature under a 5 kg piston load through an orifice having an inner diameter of 2.1 mm and a length of mm8. g / min) was taken as the melt flow rate.

The melting point was determined using a thermal analyzer (DTA) manufactured by Vacuum Riko. Place the sample in an aluminum cup and allow
The temperature was raised at 10 ° C., and the melting endothermic peak temperature was defined as the melting point.

Compound (B) can be synthesized by the following method or the like.
For example, a method described in JP-A-58-85832, specifically, CF ₂ = CFO (CF ₂ ) ₃ COOCH ₃ , CF ₂ = CFO (CF ₂ ) ₂ COOC
₂ H ₅ , CF ₂ CCFOCF ₂ CF (CF ₃ ) O (CF ₂ ) ₃ COOC ₂ After protecting the double bond of a fluorinated unsaturated carboxylic acid ester such as H ₅ with chlorine gas or the like, sodium Reduction with a reducing agent such as borohydride, lithium borohydride, potassium borohydride, lithium aluminum hydride, sodium aluminum hydride, and the like.
The target compound can be obtained by dechlorinating this with a metal such as zinc.

In the present invention, the compound (B) is a compound represented by the above formula, and R ^f is a perfluoroalkylene group or a perfluoroalkylene group containing an ether bond. In addition, when the chain of the compound (B) is long, the polymerizability decreases, and it becomes difficult to obtain a desired polymer, which is not preferable. Preferably, the number of atoms constituting the chain of R ^f is 1 to 15
belongs to.

Preferred compounds (B) include the following compounds.

_{CF 2 = CFO (CF 2)} 3 CH 2 OH, CF 2 = CFO (CF 2) 2 CH 2 OH, CF 2 = CFOCF 2 CF (CF 3) O (CF 2) 3 CH 2 OH, CF 2 = CFO [CF ₂ CF (CF ₃ ) O] ₂ (CF ₂ ) ₂ CH ₂ OH, CF ₂ = CFO [CF ₂ CF ₂ O] ₂ (CF ₂ ) ₃ CH ₂ OH.

Further, the fluorine-containing copolymer of the present invention contains a polymerized unit based on the compound (B) at a ratio of 0.1 to 20 mol%.

If the proportion of the polymerized unit based on the compound (B) is too small, it becomes difficult to obtain a fluororesin having a high elastic modulus without using a crosslinking agent. That is, a sufficient crosslinked body cannot be obtained only by the heat treatment. On the other hand, if this ratio is too large, the melting point of the fluorocopolymer decreases, and it becomes difficult to maintain the shape during the heat treatment, so that precise formation becomes difficult.
During heat treatment, internal strain is easily generated and cracks are easily generated. Also, the fluorinated copolymer becomes elastomeric,
It is not preferable because drawbacks such as a decrease in moldability occur.

In particular, 0.2 to 10 mol% of polymerized units based on the compound (B)
Is preferably contained in the ratio of

In the fluorine-containing copolymer of the present invention, in addition to the polymerized unit based on the compound (A) and the polymerized unit based on the compound (B), a compound copolymerizable with the compound (A) and the compound (B) is copolymerized. It may be. As the compound copolymerizable with the compound (A) and the compound (B), a compound (C) represented by the following formula is preferably employed.

(C) CF ₂ CFCFY (Y is a perfluoroalkyl group or a perfluoroalkoxy group) The fluorine-containing copolymer obtained by copolymerizing such a compound (C) has almost no decrease in heat resistance, chemical resistance, etc. There are advantages such as improvement in melt moldability and improvement in physical properties such as impact resistance and toughness of the fluororesin after the heat treatment.

Compound (C) is a compound represented by the above formula,
Is a perfluoroalkyl group or a perfluoroalkoxy group, from the viewpoint of heat resistance, chemical resistance and the like.
In particular, Y is a perfluoroalkyl group or a perfluoroalkyl group having 1 to 10 carbon atoms in consideration of the copolymerizability of the compound (A) and the compound (B), the physical properties of the fluorinated copolymer and the heat-treated fluorinated resin. Those with a fluoroalkoxy group are preferred.

When the compound (C) is copolymerized, the copolymerization ratio is such that the polymerized unit based on the compound (A) is 70 to 99.9 mol%,
It is preferable that the polymerization unit based on the compound (B) is 0.1 to 20 mol% and the compound (C) is 10 mol% or less. If the proportion of the unit based on the compound (C) is too large, the melting point of the fluorinated copolymer decreases, or the fluorinated copolymer becomes elastomeric, so that the moldability decreases,
Not preferred.

Further, the above-mentioned melt flow rate of the fluorinated copolymer of the present invention is from 0.01 to 100. The melt flow rate is extremely low, that is, a material having an ultrahigh molecular weight, and the melt flow rate is extremely high, that is, a material having a low molecular weight. It is not desirable.

The fluorine-containing copolymer of the present invention, solution polymerization, suspension polymerization,
It can be prepared by any method of emulsion polymerization.

Here, the polymerization initiator is preferably a free radical polymerization initiator, for example, bis (fluoroacyl) peroxides, bis (chlorofluoroacyl) peroxides,
Dialkyl peroxy dicarbonates, diacyl peroxides, peroxy esters, persulfates and the like can be mentioned.

As a polymerization medium, CFC 11 and CFC 11 are used in solution polymerization.
3, chlorofluorocarbons, tert-butanol and the like,
In suspension polymerization and emulsion polymerization, water or a mixed medium of water and another solvent is used.

The polymerization temperature is 0 ° C to 100 ° C, and the polymerization pressure is 0.5 to 30 kg / cm ² G
Can be selected from the range.

In the polymerization reaction, for example, a polymerization medium, a compound (B), a compound (C), and a molecular weight regulator as needed are first charged into an autoclave equipped with a stirrer, a required amount of the compound (A) is injected, and a polymerization initiator is added to carry out polymerization. Start. Since the pressure decreases with the progress of the polymerization, the compound (A) is injected to compensate for the decrease in the pressure, and the polymerization is continued until a desired amount of the polymer is produced. After the completion of the polymerization, the unreacted monomer is released, and the polymer is washed and dried.

The resulting copolymer can be melt-molded by heating to above the melting point of the copolymer. In addition, the molded product is 200 ° C
By performing the treatment at a temperature not lower than the melting point for 5 hours or more, the cross-linking can be performed without adding a cross-linking agent, and a molded article having a high elasticity and not flowing even at the melting point or higher can be obtained.

[Example 1] [Example 1] An autoclave with a stirrer having a content of 260 cc was charged with Freon 1
13 to 320 g, CF ₂ = CFO (CF ₂ ) ₃ CH ₂ OH 4.9 g, methanol
After charging 0.05 g, the internal space was sufficiently replaced with nitrogen gas, and this was evacuated. Then, 13 g of tetrafluoroethylene (TFE) was added to this.
Was pressurized, the temperature was raised to 50 ° C., and the mixture was stirred. 3.0 cc of a solution prepared by dissolving bis (heptafluoropropanoyl) peroxide as a polymerization initiator in 1% by weight of Freon 113 was used.
In addition, polymerization was started. During the reaction, as the pressure drops
TFE was added sequentially to maintain a constant pressure. When the sequential addition amount of TFE reached 16 g, cooling and monomer purging were performed.

The obtained slurry solution was washed with Freon 113,
For 12 hours to obtain a polymer.

 The physical properties of the polymer were measured by the following methods.

Melt flow rate and melting point (° C.) were measured by the methods described above.

The content of _{CF 2 = CFO (CF 2)} 3 CH 2 OH to the based polymer units (mol%), for example as described in USP3085083 and JP 60-240713, the infrared spectrum of the compression molded films The content of the monomer was determined as follows from the absorbance of absorption of a —CH ₂ OH group (2.75 μm).

Content of polymerized units based on the monomer (mol%) = (absorbance × 0.44) / thickness of film (mm) “Example 2” CF _{2 in} Example 1 = CFO (CF ₂ ) ₃ CH ₂ OH CF ₂ = CFO
A polymer was obtained in the same manner as in Example 1 except that 4.0 g of (CF ₂ ) ₂ CH ₂ OH was charged.

CF ₂ CCFO (CF ₂ ) ₂ The content (mol%) of the polymerized units based on CH ₂ OH was measured in the same manner as in Example 1 and determined as follows.

Content of polymerized units based on the monomer (mol%) = (absorbance × 0.44) / thickness of film (mm) “Example 3” CF _{2 in} Example 1 = CFO (CF ₂ ) ₃ CH ₂ OH CF ₂ = CFOC
A polymer was obtained in the same manner as in Example 1 except that 7.8 g of F ₂ CF (CF ₃ ) O (CF ₂ ) ₃ CH ₂ OH was charged.

CF ₂ = CFOCF ₂ CF (CF ₃ ) O (CF ₂ ) ₃ The content (mol%) of the polymerized units based on CH ₂ OH was measured in the same manner as in Example 1 and determined as follows.

Content of polymerized unit based on the monomer (mol%) = (absorbance × 0.44) / film thickness (mm) “Example 4” CF _{2 of} Example 1 = 4.9 g of CFO (CF ₂ ) ₃ CH ₂ OH Instead CF ₂ =
A polymer was obtained in the same manner as in Example 1 except that 2.5 g of CFO (CF ₂ ) ₃ CH ₂ OH and 2.4 g of CF ₂ CCFO (CF ₂ ) ₃ F were charged.

The content (mol%) of polymerized units based on CF ₂ = CFO (CF ₂ ) ₃ F is determined by measuring the absorbance at a wavenumber of 980 cm ⁻¹ measured by infrared absorption spectrum analysis of a film having a thickness of about 40 μm at a wavelength of 2350 cm ⁻¹ . Was obtained by multiplying the value obtained by dividing by the absorbance at 0.36 times.

 Table 1 shows the polymerization results of the examples.

“Test Examples” Table 2 shows the physical properties of the copolymer of each example and the PFA resin as a comparative example before and after heat treatment (300 ° C., 300 hours).

By performing the heat treatment, it was possible to obtain a molded article having a high elastic modulus, not flowing even when heated to a temperature higher than the melting point, and having excellent heat resistance and chemical resistance.

[Effects of the Invention] The fluorine-containing copolymer of the present invention has an excellent effect that it has a high modulus of elasticity by heat treatment, does not flow even when heated to a temperature higher than its melting point, and has good heat resistance and chemical resistance. Can be given.

Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08F 216: 14)

Claims (2)

(57) [Claims] 1. A copolymer of the following compound (A) and the following compound (B), wherein a polymerized unit based on (A) is 80 to 99.9 mol% and a polymerized unit based on (B) is 0.1 to 20 mol%. %, And the melt flow rate is 0.01 to 100. (A) CF ₂ CCFX (X is F or Cl) (B) CF ₂ CCFOR ^f CH ₂ OH (R ^f is a perfluoroalkylene group or a perfluoroalkylene group containing an ether bond) 2. A copolymer of the following compound (A), the following compound (B) and the following compound (C), wherein the polymerization unit based on (A) is 70 to 99.9 mol% and the polymerization based on (B) is Unit is 0.
A fluorinated copolymer containing 1 to 20 mol%, 10 mol% or less of polymerized units based on (C), and a melt flow rate of 0.01 to 100. (A) CF ₂ CCFX (X is F or Cl) (B) CF ₂ CCFOR ^f CH ₂ OH (R ^f is a perfluoroalkylene group or a perfluoroalkylene group containing an ether bond) (C) CF ₂ ＝ CFY (Y is a perfluoroalkyl group or a perfluoroalkoxy group)