JPH11181027A - Production of fluorine-containing copolymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a copolymer of a fluoroolefin excellent in copolymerizability and a (meth)acrylic ester. SOLUTION: This method for producing a fluorine-containing copolymer comprising (a) a fluoroolefin monomer unit, (b) a (meth)acrylic ester monomer unit and, if necessary, (c) other copolymerizable olefinic monomer units comprises using a peroxide-based radical initiator, charging a reaction vessel with the whole amount of the component (a) and <=40 wt.% amount of each of components (b) and (c) before the start of the polymerization, successively adding the remainder of the components (b) and (c) to the reaction vessel over 3 hr after the start of the polymerization, and carrying out the reaction at the temperature at which the half-life of a used polymerization initiator is >=2 hr.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a fluorine-containing copolymer containing fluoroolefin and alkyl (meth) acrylate as main components.

[0002]

2. Description of the Related Art Fluorine-containing copolymers are widely used in the construction field such as paints because of their excellent weather resistance. Generally, the production of a fluorine-containing copolymer is carried out in the presence of an initiator.
It is carried out by a method in which a mixture of a fluoroolefin monomer and an olefinic monomer copolymerizable with the fluoroolefin monomer is charged all at once into a reactor and copolymerized in an organic solvent. Here, vinyl esters, vinyl ethers, and the like are mainly used as the olefinic monomer copolymerizable with the fluoroolefin monomer. On the other hand, it has been considered difficult to produce a copolymer of a fluoroolefin and a (meth) acrylate from the viewpoint of copolymerizability.

[0003] Generally, the copolymerizability at the time of radical copolymerization of monomer 1 and monomer 2 is determined by the copolymerization reactivity ratio r ₁ , r ₂
(R ₁ represents the ratio of the homopolymerization rate constant (k ₁₁ ) of monomer 1 to the copolymerization rate constant (k ₁₂ ) of monomer 1 and monomer 2, and r ₂ represents The ratio of the homopolymerization rate constant (k ₂₂ ) of monomer 2 to the copolymerization rate constant (k ₂₁ ) of monomer 2 and monomer 1 is shown). Here, it is known that when the monomer 1 is a fluoroolefin and the monomer 2 is a (meth) acrylate, r ₂ is significantly larger than r ₁ (by Takaomi Satokawa, "Functional Fluoropolymers", p. 12, published by Nikkan Kogyo Shimbun. That is,
It is explained that copolymerization of a fluoroolefin and a (meth) acrylate is difficult because the homopolymerization reaction rate of the (meth) acrylate is high.

On the other hand, a sealing material using a copolymer of a fluoroolefin and an acrylic acid ester has been disclosed (Japanese Patent Application Laid-Open No. 8-127765). According to the disclosed polymerization method, the reaction is carried out by intermittently adding the acrylate ester. However, since the obtained copolymer has a composition distribution, the solid content of the copolymer is 50% by weight or more. The solution (1) has a drawback that it becomes slightly turbid.

[0005]

An object of the present invention is to provide a process for producing a copolymer of a fluoroolefin and a (meth) acrylate ester having excellent copolymerizability.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above problems, and as a result, using a peroxide system as an initiator, charging a fluoroolefin monomer in its entirety before the start of polymerization, A portion of the (meth) acrylic acid ester monomer and other copolymerizable olefin monomers are charged before the start of the polymerization, and the remainder is continuously added after the start of the polymerization, so that the fluorine content is high and the solid content is high. Min 50
The inventors have found that a copolymer free from turbidity can be obtained at a content of not less than% by weight, and have completed the present invention. That is, the present invention relates to a composition comprising (a) a fluoroolefin monomer unit, (b) a (meth) acrylic acid alkyl ester monomer unit, and optionally (c) another copolymerizable olefinic monomer unit. In the production of the fluorocopolymer, a peroxide radical initiator is used, and before the initiation of the polymerization, the total amount of (a) and 40% by weight or less of each of (b) and (c) are charged into a reactor, and (b) (C) adding the remainder of the polymerization continuously to the reactor over a period of 3 hours or more after the initiation of polymerization, and reacting at a temperature at which the half-life of the polymerization initiator used is 2 hours or more. It is a manufacturing method of united.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The fluoroolefin monomer (a) in the present invention includes tetrafluoroethylene, chlorotrifluoroethylene, hexafluoropropylene, dichlorodifluoroethylene, trifluoroethylene, vinylidene fluoride, vinyl fluoride and vinyl fluoride. Perfluoro (alkyl vinyl ether) is exemplified, but tetrafluoroethylene, chlorotrifluoroethylene and hexafluoropropylene are preferred from the viewpoint of polymerizability, and tetrafluoroethylene and chlorotrifluoroethylene are more preferred.

As the (b) alkyl (meth) acrylate monomer in the present invention, those containing an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group or a halogen-containing alkyl group as an ester chain are preferable. May be included in the ester chain as long as the atom is not impaired. However, when the proportion of these atoms is increased, the weather resistance and the stain resistance are lowered, so that the number of these atoms is preferably 5 or less in the ester chain. Specific examples of these compounds include methyl acrylate,
Ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, tert-butyl acrylate, neopentyl acrylate, 2-ethylhexyl acrylate, isodecyl acrylate, lauryl acrylate , Tridecyl acrylate, stearyl acrylate, cyclohexyl acrylate, 4-tert-butyl cyclohexyl acrylate, isobornyl acrylate, tricyclodecynyl acrylate, tetrahydrofurfuryl acrylate, acrylic Methoxyethyl acrylate, dimethylaminoethyl acrylate, chloroethyl acrylate, trifluoroethyl acrylate Glycol ester, trimethoxy silyl propyl acrylate, acrylic acid alkyl esters such as acrylic acid triethoxysilylpropyl acrylate and methyldimethoxysilylpropyl; methacrylic acid methyl ester, methacrylic acid ethyl ester, methacrylic acid propyl ester, methacrylic acid butyl ester,
Isobutyl methacrylate, tertiary butyl methacrylate, neopentyl methacrylate, ethylhexyl methacrylate, isodecyl methacrylate, lauryl methacrylate, tridecyl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, Isobornyl methacrylate, tricyclodecynyl methacrylate, tetrahydrofurfuryl methacrylate, methoxyethyl methacrylate, dimethylaminoethyl methacrylate,
Chloroethyl methacrylate, trifluoroethyl methacrylate, 2-hydroxyethyl methacrylate, hydroxybutyl methacrylate, ε-caprolactone addition product of hydroxyethyl methacrylate, trimethoxysilylpropyl methacrylate, triethoxy methacrylate Examples include alkyl methacrylates such as silylpropyl and methyldimethoxysilylpropyl methacrylate, and these may be used alone or as a mixture of several types. Among these, alkyl acrylates are preferred from the viewpoint of polymerizability with a fluoroolefin.

The (c) other copolymerizable olefinic monomer in the present invention includes, but is not limited to, α-olefins, vinyl ethers, vinyl esters, styrene, acrylonitrile, and acrolein. . Specifically, α-olefins include 1-butene, isobutene and 1-octene, and alkyl vinyl ethers include ethyl vinyl ether, butyl vinyl ether, tertiary butyl vinyl ether, 2-ethylhexyl vinyl ether and cyclohexyl vinyl ether. Examples of the esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl caprylate, vinyl 2-ethylhexanoate, vinyl laurate, and vinyl benzoate. Further, if necessary, a monomer containing a functional group such as a hydroxyl group or a hydrolyzable silyl group may be used. To be more specific, examples of the hydroxyl group-containing monomer include hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, hydroxypropyl vinyl ether, hydroxyethyl allyl ether, hydroxybutyl allyl ether, hydroxyethyl crotonate, 2-hydroxyethyl acrylate, and hydroxy acrylate. Butyl, hydroxypropyl acrylate, ε-caprolactone addition reaction product of hydroxyethyl acrylate, and as a hydrolyzable silyl group-containing monomer, trimethoxyvinylsilane, methyltriethoxyvinylsilane, methyldimethoxyvinylsilane, methacrylic acid Trimethoxysilylpropyl, triethoxysilylpropyl methacrylate, methyldimethoxysilylpropyl methacrylate, trimethoxy acrylate Silyl propyl, triethoxysilylpropyl acrylate, methyldimethoxysilylpropyl acrylic acid, trimethoxysilylpropyl vinyl ether and trimethoxysilyl undecanoic acid vinyl.

One of the features of the method for producing a fluorine-containing copolymer in the present invention is that a peroxide radical initiator is used as a polymerization catalyst as an initiator. By using a peroxide radical initiator, a copolymer having a high fluorine content can be obtained. Examples of the peroxide radical initiator include ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxydicarbonates, and peroxyesters. Among these, peroxy ketals, diacyl peroxides, peroxy dicarbonates and peroxy esters are preferred. Specifically, 1,1-bis (tert-butylperoxy) cyclohexane and 1,1-bis (tert-hexylperoxy) cyclohexane for peroxyketals and 3,5,5-diacyl peroxides for diacyl peroxides Examples of peroxydicarbonates such as trimethylhexanoyl peroxide, octanoyl peroxide, benzoyl peroxide, and lauroyl peroxide include diisopropyl peroxy dicarbonate, di-2-ethoxyethyl peroxy dicarbonate, and di-2-ethylhexyl peroxy. For peroxyesters such as dicarbonate, tertiary butyl peroxy neodecanoate, tertiary butyl peroxypivalate, tertiary butyl peroxyisobutyrate and tertiary butyl peroxyester Kishiraureto, and the like. The method of adding the initiator is not particularly limited, and the initiator may be charged at once or may be added intermittently. Moreover, you may add continuously like a monomer.

In the production method of the present invention, before the polymerization is started, the total amount of (a) and 40% by weight or less of each of (b) and (c) are charged into a reactor, and (b) and (b) After the start of the polymerization, the remainder of c) is continuously added to the reactor over a period of 3 hours or more by a high-pressure constant flow pump or the like.
The continuous addition time is preferably 6 hours or more. The ratio of the monomers (b) and (c) to be added and the rate of addition need not always be constant, and the amount added can be arbitrarily changed for each monomer. The period of the continuous addition may be over the entire period of the polymerization reaction or a part of the period. However, when the continuous addition time is less than 3 hours, the polymerization of the (meth) acrylic ester takes precedence. To happen
Since the copolymerization ratio of the fluoroolefin in the copolymer decreases and the composition distribution of the polymer becomes broader, the obtained copolymer does not have the desired physical properties and the solid content is 50% by weight. % Or more when it is made into a solution.

In the case of (b) and (c), when an amount exceeding 40% by weight of the total amount is charged into the reactor before the start of the reaction or when the addition is not continuous but intermittent, the fluoroolefin and The copolymerizability with (meth) acrylic acid ester decreases. Further, the ratio of the total amount of (a) :( b) and (c) is from 10:90 to 95: 5 in molar ratio.
Is preferred. When the ratio of (a) is less than 10:90 and more than 95: 5, there is not much difference from the case of the initial preparation, and the technical significance of continuous addition is lost.
Further, the ratio of the total number of moles of (b) / the total number of moles of (c) is preferably 1.5 or more. When a monomer having low copolymerizability with a fluoroolefin is used as (c), if the ratio of the total number of moles of (b) / the total number of moles of (c) is less than 1.5, continuous addition is required. This is because a copolymer having a high fluorine content cannot be obtained.

In the present invention, it is necessary to carry out the polymerization reaction at a temperature at which the half life of the initiator used is 2 hours or more. For example, when the initiator is benzoyl peroxide, the temperature at which the half life is 2 hours is 85 ° C.
Polymerization will be performed at a temperature of 5 ° C. or less. When the polymerization is carried out at a temperature at which the half-life of the initiator used is less than 2 hours,
Since the polymerization of the (meth) acrylic ester occurs preferentially, the copolymerization ratio of the fluoroolefin in the copolymer decreases, and the composition distribution of the polymer becomes broader.
The resulting copolymer does not have the desired physical properties and may become cloudy when formed into a solution having a solid content of 50% by weight or more.

As the polymerization method, a usual method such as suspension polymerization and emulsion polymerization in an aqueous medium or solution polymerization in an organic solvent can be adopted. Among these, solution polymerization is preferable. Examples of the organic solvent include cyclic ethers such as tetrahydrofuran and dioxane; aromatic hydrocarbon compounds such as benzene, toluene, xylene and solvesso; aliphatic hydrocarbons such as mineral spirit and exol (Exxon) solvent naphtha; ethyl acetate, acetic acid Esters such as butyl and isobutyl acetate; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; alcohols such as ethanol, isopropyl alcohol and normal butanol; 1,1,2-trichloro-1,2,2-tri Fluorinated solvents such as fluoroethylene; cellosolves such as methyl cellosolve, normal butyl cellosolve and normal butyl cellosolve acetate; propylene glycol monomethyl ether; B include propylene glycol monobutyl ether and propylene glycol monomethyl ether acetate, among these, hydrocarbon solvents or fluorinated organic solvents, etc. are suitable, organic solvent for dissolving the copolymer is particularly preferred. Examples of the emulsifier in the case of emulsion polymerization include potassium perfluorooctanoic acid and ammonium salts, ammonium perfluorooctanesulfonate, sodium salts of higher alcohol sulfates, and polyethylene glycol ether.

Other polymerization conditions include a pressure of 1 to 20.
The reaction can be performed using a pressure-resistant autoclave at 0 kg / cm ² for a reaction time of 3 to 40 hours. If necessary, potassium carbonate, sodium hydrogen carbonate, hydrotalcite, an anion exchange resin and the like may be added as a pH adjuster.
Hereinafter, specific examples will be described.

[0016]

Examples 1 to 6 and Comparative Examples 1 to 6 Table 1 below shows the types and amounts of the monomers, initiators and organic solvents used in the examples and comparative examples, and the monomer addition time and the like. Was. The term “initial” refers to the amount charged in the reactor before polymerization. Table 1 also shows the number average molecular weight in terms of polystyrene, the value of fluorine analysis (% by weight), and the appearance of the copolymer obtained by gel permeation chromatography (GPC) of the obtained copolymer. In addition,
Each abbreviation in Table 1 means the following compounds. CTFE: chlorotrifluoroethylene BA: butyl acrylate HA: 2-ethylhexyl acrylate VAc: vinyl acetate CHA: cyclohexyl acrylate VLu: vinyl laurate HEA: 2-hydroxyethyl acrylate VMS: vinyl trimethoxysilane EEP: di- 2-ethoxyethyl peroxydicarbonate IPP diisopropyl peroxydicarbonate HPD di (2-ethylhexylperoxy) dicarbonate BPP tertiary butyl peroxypivalate LP lauroyl peroxide BuAc butyl acetate ADVN 2,2 -Azobis (2,4-dimethylvaleronitrile)

Example 1 A 2-liter stainless steel autoclave equipped with a stirrer was charged with ethyl acetate as an organic solvent and EEP as an initiator.
And each monomer shown in Table 1 was charged. Next, after degassing and nitrogen substitution were repeated three times, degassing was performed again, and CTFE was charged. The temperature was raised to 50 ° C. to start the polymerization, and immediately after the start of the polymerization, the remainder of the monomer was continuously added into the autoclave at a constant speed using a high-pressure constant flow pump for the time shown in Table 1. After the polymerization was carried out for a total of 8 hours, unreacted CTFE was purged, 12 g of sodium borate was added, the temperature was raised again to 40 ° C., and the mixture was stirred for 2 hours. After cooling, the autoclave was opened to obtain a copolymer solution. The obtained solution was filtered to remove sodium borate, and then dried to obtain 330 g of a transparent copolymer. Table 1 shows the number average molecular weight of the obtained copolymer, the value of fluorine analysis (% by weight), and the appearance of the copolymer.

Examples 2 to 6 The reaction was carried out in the same manner as in Example 1 with the formulation shown in Table 1 including the initiator, the type and amount of the monomer, and the ratio of the initial charge amount and the continuous addition amount of the monomer. Was done. Table 1 shows the results.

Comparative Examples 1 to 6 Copolymers were produced in the same manner as in Examples except that the following details were changed. Comparative Example 1 Example 1 except that all the monomers used were initially charged.
Polymerization was carried out in the same manner as described above. Comparative Example 2 Example 3 except that all the used monomers were initially charged.
Polymerization was carried out in the same manner as described above. Comparative Example 3 Without continuously adding (meth) acrylic acid ester, BA and HA were replaced with 13.9 g and 20.
Polymerization was carried out in the same manner as in Example 1 except that the addition was intermittently carried out at 0 g each, at the start of the polymerization and at four times every two hours thereafter. Comparative Example 4 Polymerization was carried out in the same manner as in Example 1 except that the time for continuous addition of monomers and the time for polymerization were shortened. Comparative Example 5 Polymerization was carried out in the same manner as in Example 1 except that ADVN was used as an initiator. Comparative Example 6 The temperature used was such that the half-life of the initiator used was 1 hour, and the initiator was divided into an initial stage and 2 hours after the start of polymerization, and was 1.9 g.
Polymerization was carried out in the same manner as in Example 1 except that they were added one by one.

[0020]

[Table 1]

The results of the above Examples and Comparative Examples are summarized as follows. From Examples 1 and 3 and Comparative Examples 1 and 2, (meth)
It can be seen that when the acrylic ester is reacted in the initial batch charge, the fluorine content of the obtained copolymer decreases and the copolymer becomes cloudy. From Example 1 and Comparative Example 3, it can be seen that when the reaction is carried out by intermittent addition of the (meth) acrylate, the fluorine content of the obtained copolymer decreases and the copolymer becomes cloudy. From Example 1 and Comparative Example 4, it can be seen that when the continuous addition time of the (meth) acrylic acid ester is shortened, the fluorine content of the obtained copolymer decreases and the copolymer becomes slightly cloudy. From Example 1 and Comparative Example 5, when an azo-based initiator was used as the initiator, the fluorine content of the obtained copolymer was reduced,
Further, it is found that the copolymer becomes slightly cloudy. From Example 1 and Comparative Example 6, it can be seen that when polymerization was performed at a temperature at which the half-life of the initiator was less than 2 hours, the fluorine content of the resulting copolymer was reduced.

[0022]

According to the production method of the present invention, it is possible to obtain a copolymer of a fluoroolefin and a (meth) acrylic acid ester, which has heretofore been considered to have poor copolymerizability, and to obtain a copolymer of the obtained copolymer. Since the fluorine content is high and the obtained solution does not show turbidity, it can be widely used in the field of paints and the like.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Etsuzo Marumoto 1 in Funami-cho, Minato-ku, Nagoya-shi, Aichi

Claims (1)

[Claims] (1) (a) a fluoroolefin monomer unit,
In the production of the fluorine-containing copolymer (b) comprising a (meth) acrylic acid alkyl ester monomer unit and optionally (c) other copolymerizable olefinic monomer unit, a peroxide radical initiator is used, Before the start of polymerization, the total amount of (a) and 4 of each of (b) and (c)
0% by weight or less is charged into a reactor, the remainder of (b) and (c) are continuously added to the reactor over 3 hours or more after the initiation of polymerization, and the half life of the polymerization initiator used is 2 hours or more. A method for producing a fluorine-containing copolymer, wherein the reaction is carried out at a predetermined temperature.