JPS6021644B2 - Curable fluorine-containing copolymer and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a curable fluorine-containing copolymer and a method for producing the same. The present invention relates to a useful curable fluorine-containing copolymer and a method for producing the same.

Copolymers of fluoroolefins and general alkyl vinyl ethers or substituted alkyl vinyl ethers have been known, for example, as disclosed in U.S. Pat. No. 2,834,7.
Various examples are exemplified in the specification of No. 67.

However, such known copolymers do not have curability per se and have low rigidity, and have the disadvantage that they cannot be used in applications requiring surface hardness, for example, as paint resins. On the other hand, the present applicant has discovered that a new copolymer of fluoroolefin and cyclohexyl vinyl ether has high rigidity and can be cured by heating in the presence of oxygen or by exposing it to a specific neck ray in a similar atmosphere. We have found that this is possible (see Japanese Patent Application Laid-Open No. 53-960, etc.).

As a result of further research into the industrial use of such copolymers, the present inventors found that the copolymers are transparent, have high surface hardness, and are advantageous in forming coatings with excellent weather resistance. Although it is extremely useful and can be applied to a wide range of applications such as pre-coated metal, its flexibility and properties are insufficient for applications where bending is performed after coating is formed, such as with pre-coated metal. Understood. Based on the recognition of the above-mentioned problems, the present inventors have conducted intensive research and found that a copolymer of fluoroolefin and vinyl ether is produced, and the fluoroolefin component contains a small amount of tetrafluoroethylene and co-trifluoroethylene. A fluorine-containing copolymer in which the vinyl ether component contains both a specific alkyl vinyl ether and a cyclohexyl vinyl ether, and the ratio thereof is within a specific range, solves the above problems and has high surface hardness and It has been found that it has both excellent bending workability and provides a curable coating film.

Thus, the present invention has been completed based on the above findings, and includes at least one fluoroolefin selected from tetrafluoroethylene and chlorotrifluoroethylene, the alkyl group having 2 to 8 carbon atoms. It is a copolymer containing units based on alkyl vinyl ether and cyclohexyl vinyl ether, and the content of units based on fluoroolefin is 40 to 60 mol%. The molar ratio of cyclohexyl vinyl ether to the alkyl vinyl ether is ( 1/9) to (9/1), and the intrinsic viscosity measured at 30°C in tetrahydrofuran is 0.1 to
2. The present invention provides a new curable fluorine-containing copolymer and a method for producing the same.

In the fluorine-containing copolymer of the present invention, the content of units based on at least one fluoroolefin selected from tetrafluoroethylene and chlorotrifluoroethylene is 40 to 60 mol%, preferably 45 to 55 mol%. This is very important.

Too low a content is not only unfavorable in terms of weather resistance, but also causes inconvenience in manufacturing. Also, those containing too high a content are also difficult to manufacture. In the fluorine-containing copolymer of the present invention, both an alkyl vinyl ether and a cyclohexyl vinyl ether in which the alkyl group has 2 to 8 carbon atoms are contained in a molar ratio of cyclohexyl pinyl ether to the alkyl pinyl ether. (1/9)
It is important to contain it in a ratio of ~(9/1). If the cyclohexyl vinyl ether content is too low, the crosslinkability and surface hardness when formed into a coating film will be lowered, while if the alkyl vinyl ether content is too low, the flexibility will be lowered, which is undesirable. When using chlorotrifluoroethylene as the fluoroolefin or when using an alkyl pinyl ether with a small number of carbon atoms in the alkyl group, the molar ratio of cyclohexyl pinyl ether to alkyl vinyl ether should be adjusted relatively. It is preferable to make it small from the viewpoint of improving flexibility. For example, when using chlorotrifluoroethylene as the fluoroolefin and ethyl vinyl ether as the alkyl pinylether, the molar ratio of the content is (
A range of 1/9) to 2/3 can be preferably adopted. The English polymer of the present invention also has an intrinsic viscosity of 0.1 to 2.0 as measured at 30 qo in tetrahydrofuran. End/evening, preferably 0.3 to 0. It is important that it is Banyu/Yu. If the intrinsic viscosity is too low, the mechanical strength will decrease, while if the intrinsic viscosity is too high, the solution concentration will have to be lowered from the viewpoint of viscosity when applied as a solution-type paint, so both are undesirable. The above-mentioned fluorine-containing copolymer is produced by copolymerizing a fluoroolefin and an alkyl vinyl ether in a polymerization medium under the action of a polymerization initiator to produce a fluorine-containing copolymer. At least one selected from fluoroethylene and chlorotrifluoroethylene,
As an alkyl vinyl ether, the number of carbon atoms in the alkyl group is 2
to 8, preferably 2 to 4, and cyclohexyl vinyl ether is allowed to coexist in a molar ratio of 1/9 to 9/1 to the alkyl pinylether to carry out the copolymerization reaction with respect to the fluoroolefin. Total charging molar ratio of alkyl vinyl ether and cyclohexyl vinyl ether (80/20) to (20/80) temperature -3
It can be manufactured by using a method of 0 to 115,000 pi.

In the method of the present invention, the polymerization initiation source is not particularly limited, and may include polymerization initiators such as peroxides and azo compounds, as well as ionizing radiation.

Further, in the method of the present invention, any water-soluble and oil-soluble polymerization initiator can be employed. As a specific example, the water-soluble initiator may include a redox initiator consisting of a persulfate such as potassium persulfate, hydrogen peroxide, or a combination of these with a reducing agent such as sodium bisulfite or sodium thiosulfate; is an inorganic initiator such as a system in which a small amount of iron, ferrous salt, silver nitrate, etc. is coexisting with these, or dibasic acid peroxide such as disuccinic acid peroxide, diglutaric acid peroxide, monosuccinic acid peroxide, azobis Organic initiators such as isobutyramidine dihydrochloride, oil-soluble initiators such as t-butyl/dioxyisobutyrate, t-butylperoxyacetate, and peroxyester type peroxides. , dialkyl peroxy dicarbonates such as diisopropyl peroxy dicarbonate, penzoyl peroxide, azobisisobutyronitrile, and the like. The amount of polymerization initiator used can be changed as appropriate depending on the type, copolymerization reaction conditions, etc., but it is usually 0.005% of the total amount of monomers to be copolymerized.
~5% by weight, particularly about 0.05 to 0.5% by weight is employed. In the copolymerization reaction of the present invention, the reaction format is not particularly limited, and bulk polymerization, suspension polymerization, emulsion polymerization, solution polymerization, etc. can be adopted, but the stability of the polymerization reaction operation, From the viewpoint of ease of separation, emulsion polymerization in an aqueous medium or solution polymerization using a saturated halogenated hydrocarbon containing one or more fluorine atoms as a solvent is preferably employed.

In addition, when carrying out a copolymerization reaction in an aqueous medium, it is preferable to add a basic buffer so that the pH value of the liquid during polymerization does not fall below 4, preferably 6. still,
It goes without saying that the method of the present invention can be carried out by batch, semi-continuous, continuous, etc. operations. In the copolymerization reaction of the present invention, the copolymerization reaction temperature can be appropriately selected within the range of -30qo to +150°C depending on the polymerization initiation source, the type of polymerization medium, etc.; When performing
A time of around 90:00 may be adopted.

In addition, the reaction pressure can be selected as appropriate, but is usually 1 to 1
It is desirable to use 0k9/enemy, especially around 2 to 50[9/enemy]. Further, in order to suppress the intrinsic viscosity of the resulting copolymer within the above range, it is possible to carry out the polymerization reaction in the presence of an appropriate chain transfer agent.

When the copolymer of the present invention is applied as a coating resin, it has both high surface hardness and excellent bending workability, and provides a curable coating film, which is similar to precoated metal. It is extremely useful for applications where bending is performed after formation.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 In a ferrous steel reactor with an internal volume of 100, 402 g of deoxygenated water, 0.02 g of ammonium persulfate, 0.002 g of sodium bisulfite, 0.72 g of disodium hydrogen phosphate decahydrate, and perfluorinated water were added. Add 0.080 g of ammonium octoate, and then the total amount of monomer is 2
After charging a predetermined amount of cyclohexyl vinyl ether and ethyl vinyl ether calculated to reach a predetermined charge molar ratio and reaching a predetermined charge molar ratio, the inside of the vessel was deaerated and replaced with nitrogen several times, and then a predetermined amount of chlorotrifluoroethylene was added. was press-fitted.

A stable emulsion containing fine copolymer particles was obtained by carrying out a copolymerization reaction by shaking in a constant temperature water bath maintained at 65 oo for 1.5 to 2 hours. The emulsion is dropped into a water/ethanol mixed solution to which a small amount of hydrochloric acid has been added to destroy the emulsification, the copolymer is separated by filtration, and the copolymer is thoroughly washed with water and ethanol. It was vacuum dried at 30°C.

The thus obtained copolymer was dissolved in a mixed solvent of methyl isobutyl ketone and xylene at a ratio of 75:25 (weight ratio).
．． Film applicator on 8-leg thick aluminum slope
(JISK540 hypertrophic gap 100),
After air-drying at room temperature for 10 minutes, the coating film was heated for 30 minutes in an electric furnace (atmosphere: air) maintained at 210°C, and the cure degree, surface hardness, and bending workability of the coating film formed were tested.

The degree of hardening was determined by the amount of elution when the coating film formed on the glass plate was peeled off and immersed in 2yo of xylene for 2 hours. Bendability is determined by the maximum hardness that does not cause scratches on the paint film when heated to ℃ and drawn with drafting pencils of various hardnesses. Using the minimum n (indicated as bending resistance rT) that does not cause damage to the coating film when bent, and a DuPont impact tester, the weight is lk9, the connecting core diameter is 1/2'', and the falling distance is measured. Judgment was made based on the state of the coating film when tested under 50 conditions.

The molar ratio of monomers charged in the above copolymerization reaction, the average polymerization rate, and the resulting copolymer in tetrahydrofuran at 30°C.
Table 1 summarizes the relationship between the intrinsic viscosity measured in and the physical properties of the coating film.

Note that experiment numbers 1 and 6 are for comparison. Table 1: The composition of the copolymer obtained on CTFE: Chlorotrifluoroethylene EVE: Ethyl Pinyl Able CHVE: Cyclohexyl Pinyl Ether is close to the starting composition, and the copolymer obtained in Experiment Nos. 2 and 3 The compositional ratio (molar ratio) measured by 13C NMR of the combined product was 52.3/28.8/18.
8], [51.0/19.7/29.3].

The infrared absorption spectrum and 13CNMR spectrum of the copolymer of Experiment No. 4 are shown in FIG. 1 and FIG. 2, respectively.

FIG. 2 shows measurements taken using an old JEOL FX-100 FT-NM device with a triple resonance head attached, and the measurement conditions are as follows. resonant magnetic field
23400 Gauss Solvent:
C6D6 measurement temperature
100C0 observation nucleus: 13C05
0 same day z) Irradiation nuclear: lfl (99,61M review), 19F
(93,71MHZ) Pulse width 14
Mountain sec (600) number of pulses
56000 times spectrum width:
5000 days 2RF amplifier:
22×Illusion b The numbers in the figure in FIG. 2 are the chemical shifts (skin) of each peak based on TMS, and were assigned as shown in Table 2.

Table 2 Example 2 Chlorotrifluoroethylene/n-butyl vinyl ether/cyclohexyl A vinyl ether terpolymer was obtained.

Table 3 summarizes the relationship between the molar ratio of the monomers charged in the above copolymerization reaction, the average polymerization rate, the intrinsic viscosity of the resulting copolymer, and the physical properties of the coated material subjected to the same heat treatment as in Example 1.

Note that experiment number 9 is for comparison. Table 3 Example 3 Tetrafluoroethylene/n-butyl vinyl ether/cyclohexyl was prepared in the same manner as in Example 2 except that tetrafluoroethylene (TFE) was used instead of chlorotrifluoroethylene as the fluoroolefin. A vinyl ether ternary compound was obtained.

Table 4 shows the relationship between the molar ratio of the monomers charged in the above copolymerization reaction, the average polymerization rate, the intrinsic viscosity of the resulting copolymer, and the physical properties of the coating film subjected to the same heat treatment as in Example 1.

Note that experiment number 10 is for comparison. Table 4

[Brief explanation of the drawing]

FIGS. 1 and 2 show the infrared absorption spectrum and 13CNMR spectrum of the chlorotrifluoroethylene/ethyl vinyl ether/cyclohexyl vinyl ether terpolymer obtained in Experiment No. 4 of Example 1, respectively. Hair' figure 2

Claims (1)

[Scope of Claims] 1. At least one fluoroolefin selected from tetrafluoroethylene and chlorotolyloethylene, an alkyl vinyl ether in which the alkyl group has 2 to 8 carbon atoms, and a copolymer containing a unit based on cyclohexyl vinyl ether. It is a polymer, the content of units based on fluoroolefin is 40 to 80 mol%, the molar ratio of cyclohexyl vinyl ether to the alkyl vinyl ether is (1/9) to (9/1), and the content is 40 to 80 mol%. Measured intrinsic viscosity is 0.1 to 2.0
dl/g. 2. The copolymer according to claim 1, wherein the fluoroolefin is chlorotrifluoroethylene and the alkyl vinyl ether is ethyl vinyl ether. 3 The content of units based on chlorotrifluoroethylene is 45 to 55 mol%, and the molar ratio of cyclohexyl vinyl ether to ethylene vinyl ether is (1
/9) to (2/3). 4. The copolymer according to claim 1, which has an intrinsic viscosity of 0.3 to 0.8. 5. In producing a fluorine-containing copolymer by copolymerizing a fluoroolefin and an alkyl vinyl ether in a polymerization medium by the action of a polymerization initiator, a fluoroolefin selected from tetrafluoroethylene and chlorotrifluoroethylene is used as the fluoroolefin. One type of alkyl vinyl ether is used in which the alkyl group has 2 to 8 carbon atoms, and the molar ratio of cyclohexyl vinyl ether to the alkyl vinyl ether is (1/9).
The copolymerization reaction was carried out at a molar ratio of the total charge of alkyl vinyl ether and cyclohexyl vinyl ether to fluoroolefin (80/1).
/20) ~ (20/80), temperature -30℃ ~ +150℃
1. A method for producing a curable fluorine-containing copolymer, the method comprising: 6. The copolymer according to claim 5, wherein the fluoroolefin is chlorotrifluoroethylene and the alkyl vinyl ether is ethyl vinyl ether. 7. The method according to claim 5, wherein the copolymerization reaction is carried out at a temperature of 0°C to +100°C using a water-soluble radical initiator as a polymerization initiation source and an aqueous medium containing an emulsifier and a buffer as a polymerization medium. Method.