阅读说明：本技术 一种水溶性改性feve树脂及其制备方法 (Water-soluble modified FEVE resin and preparation method thereof ) 是由 宿梅香 郭希刚 张景海 赵继华 石养渡 于 2020-07-06 设计创作，主要内容包括：本发明涉及一种高耐候性、高耐水性、高光泽的氟碳涂料用FEVE树脂水性分散液的制备方法。由氟烯烃、非氟烯烃、亲水大分子单体等共聚而成,然后除去溶剂,经过中和过程或水解过程,利用水溶性有机溶剂通过相转移而制成水性分散液。不含乳化剂而具有与溶剂型FEVE树脂相当的耐候性、耐水性和高光泽性。(The invention relates to a preparation method of an FEVE resin aqueous dispersion liquid for fluorocarbon coatings with high weather resistance, high water resistance and high gloss. Is prepared through copolymerizing fluoroolefin, non-fluoroolefin, hydrophilic macro monomer, removing solvent, neutralizing or hydrolyzing, and phase transfer with water-soluble organic solvent. Does not contain an emulsifier and has weather resistance, water resistance and high gloss which are equivalent to those of solvent-type FEVE resin.)

1. A water-soluble modified FEVE resin is characterized by being prepared from the following raw materials: 30-70 parts of fluorinated olefin, 5-45 parts of cyclohexyl vinyl ether, 1-10 parts of hydrophilic macromonomer A, 1-20 parts of hydrophilic macromonomer B, 5-45 parts of alkyl vinyl ether and 3-20 parts of omega-hydroxy butyl vinyl ether; the parts are parts by weight;

the structure of the hydrophilic macromonomer A is as follows:

CH₂=CH(CH₂CH₂)_mCOOM or CF₂=CFOCF₂CF(CF₃)OCF₂CF₂SO₂F；

The structure of the hydrophilic macromonomer B is as follows: CH (CH)₂=CHOCH₂CH₂CH₂(OCH₂CH₂O)_nOR。

2. The resin as claimed in claim 1, wherein the molecular weight of the resin is 4000-40000.

3. The resin according to claim 1, wherein in the hydrophilic macromonomer B, n is in the range of 2 to 30; r is C1-3 alkyl.

4. The resin according to claim 1, wherein m of the hydrophilic macromonomer A is in the range of 3 or 4; the M can be a hydrogen atom, an alkali metal or a quaternary amine group.

5. A method for preparing the resin of claim 1, which comprises:

(1) adding a mixed organic solvent serving as a polymerization medium into a reaction kettle, adding a molecular weight regulator and an acid absorbent, adding each reaction monomer according to a proportion, heating to 40-90 ℃, adding an initiator, and carrying out solution polymerization to obtain a FEVE solution;

(2) evaporating to recover organic solvent for polymerization to obtain dried sheet FEVE resin, dissolving in water-soluble organic solvent, and neutralizing with alkali; or heating and hydrolyzing the sheet FEVE resin in the presence of an alkali aqueous solution, evaporating water again, drying to obtain block or sheet FEVE resin, and dissolving in a water-soluble organic solvent;

(3) adding deionized water into the solution, stirring to form mixed dispersion, and then carrying out reduced pressure distillation to recover the water-soluble organic solvent, thereby obtaining the modified FEVE resin aqueous dispersion with low organic solvent content.

6. The method according to claim 5, wherein the mixed organic solvent is a mixed solution of one of xylene, toluene, butyl acetate and ethyl acetate, and one of methanol, ethanol and tert-butanol.

7. The method of claim 5, wherein the initiator is selected from the group consisting of AIBN, succinyl peroxide, t-butyl peroxypivalate, benzoyl peroxide, diisopropyl peroxydicarbonate; the amount is 0.05-0.5wt% of the polymerized monomers.

8. The method of claim 5, wherein the water-soluble organic solvent is an alcohol or a ketone.

9. The method of claim 5, wherein the aqueous dispersion of the modified FEVE resin has a solids content of 30-55%.

Technical Field

The invention relates to the field of coatings, in particular to a fluorocarbon coating and a preparation method thereof.

Background

The fluorine-containing copolymer resin is obtained by free radical copolymerization of fluorine-containing olefin such as fluoroolefin tetrafluoroethylene or chlorotrifluoroethylene and fluorine-free olefin vinyl ether or vinyl ester, and has various protection characteristics such as excellent weather resistance, corrosion resistance, chemical inertness and the like due to the protection effect of fluorine atoms on a carbon chain framework, so that the fluorine-containing copolymer resin is used for an anti-corrosion weather-resistant coating. The traditional fluorine-containing copolymer resin for the normal temperature curing coating is mainly FEVE resin, is solvent-based resin obtained by solution polymerization, and the volatilization of a solvent in a film forming process after coating easily causes environmental pollution, so that the use of the solvent-based FEVE is gradually reduced along with the enhancement of environmental protection consciousness of people in recent years. Therefore, the development of aqueous FEVE resins having performance equivalent to or higher than that of solvent-based FEVE resins is urgently needed.

The current FEVE resin polymerization technology is obtained by solution polymerization or emulsion polymerization of fluoroolefin and non-fluoroolefin in the presence of emulsifier.

The aqueous FEVE resin is mainly synthesized by emulsion polymerization in the presence of a large amount of emulsifier, such as patents CN110325582A, CN 201911421701. A large amount of emulsifier is required to be added in the emulsion polymerization process to ensure a certain reaction speed, the obtained water-based emulsion contains a large amount of emulsifier, the emulsifier existing in a coating film is a water-soluble substance, the emulsifier can be dissolved out when meeting water after being prepared into a paint film, and the water resistance is insufficient after the paint film is formed by spraying or roller coating, so that the problems of reduced compactness, whitening and the like of the coating film are caused.

Furthermore, the FEVE resin obtained by emulsion polymerization has a high molecular weight, and when a curing agent is added to form a coating, it is difficult to quantitatively perform a uniform crosslinking reaction with the curing agent, and thus there is a problem that toughness is insufficient. These all lead to insufficient film properties with the addition of emulsifiers.

At present, the invention patent CN102177208A reports that FEVE resin solution with high hydroxyl content is obtained by solution polymerization in organic solvent, carboxyl is introduced by esterification reaction for several hours with anhydride, then alkali is added for neutralization, deionized water is added and organic solvent is removed completely, and the FEVE resin aqueous dispersion with high weather resistance and water resistance is obtained.

Disclosure of Invention

Aiming at the problems of large dosage of emulsifier and poor weather resistance, water resistance and glossiness of the water-soluble FEVE resin in the prior art. The invention provides a modified FEVE resin and a preparation method thereof.

A water-soluble modified FEVE resin is prepared from the following raw materials: 30-70 parts of fluoroolefin TFE, 5-45 parts of cyclohexyl vinyl ether, 1-10 parts of hydrophilic macromonomer A, 1-20 parts of hydrophilic macromonomer B, 5-45 parts of alkyl vinyl ether and 3-20 parts of omega-hydroxybutyl vinyl ether; the parts are parts by weight;

the fluorine-containing olefin is preferably one of tetrafluoroethylene, chlorotrifluoroethylene, vinylidene fluoride, pentafluoropropylene and hexafluoropropylene, more preferably tetrafluoroethylene or chlorotrifluoroethylene, and still more preferably tetrafluoroethylene.

The structure of the hydrophilic macromonomer A is as follows: CH (CH)₂=CH(CH₂CH₂)_mCOOM or CF₂=CFOCF₂CF(CF₃)OCF₂CF₂SO₂F; the structure of the hydrophilic macromonomer B is as follows: CH (CH)₂=CHOCH₂CH₂CH₂(OCH₂CH₂O)_nOR。

Wherein the molecular weight of the modified FEVE resin is 4000-40000.

Wherein in the hydrophilic macromonomer B, the value range of n is 2-30; r is C1-3 alkyl.

Wherein, the value range of m of the hydrophilic macromonomer A is 3 or 4; the M can be a hydrogen atom, an alkali metal or a quaternary amine group. If M is a hydrogen atom, it is necessary to add a base for neutralization after completion of the polymerization. If the hydrophilic macromonomer B is CF₂=CFOCF₂CF(CF₃)OCF₂CF₂SO₂F, adding alkali metal such as KOH or NaOH or alkalis such as ammonia water and the like after the polymerization is finished, and heating for 1-20 hours for hydrolysis.

The preparation method of the resin is specifically prepared by the following steps:

(1) adding a mixed organic solvent serving as a polymerization medium into a reaction kettle, adding a molecular weight regulator and an acid absorbent, adding each reaction monomer according to a proportion, heating to 40-90 ℃, adding an initiator, and carrying out solution polymerization to obtain a FEVE solution;

(2) evaporating to recover the mixed organic solvent for polymerization to obtain dry sheet FEVE resin, dissolving in water-soluble organic solvent, and neutralizing with alkali; or heating and hydrolyzing the sheet FEVE resin in the presence of an alkali aqueous solution, evaporating water again, drying to obtain block or sheet FEVE resin, and dissolving in a water-soluble organic solvent;

(3) adding deionized water into the solution, stirring to form mixed dispersion, and then carrying out reduced pressure distillation to recover the water-soluble organic solvent, thereby obtaining the modified FEVE resin aqueous dispersion with low organic solvent content.

Wherein the mixed organic solvent is a mixed solution of one of xylene, toluene, butyl acetate and ethyl acetate and one of methanol, ethanol and tert-butyl alcohol.

Wherein the initiator can be AIBN, succinyl peroxide, tert-butyl peroxypivalate, benzoyl peroxide and diisopropyl peroxydicarbonate; the amount is 0.05-0.5wt% of the polymerized monomers.

Wherein, the water-soluble organic solvent is alcohols or ketones. Alcohols such as methanol, ethanol, n-propanol, isopropanol, n-butanol, t-butanol, propylene glycol derivatives such as propylene glycol methyl ether, propylene glycol butyl ether; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone.

Wherein the solid content of the modified FEVE resin aqueous dispersion liquid is 30-55%.

Preferably, in step (1), the polymerization time is generally 4 to 30 hours, and more preferably 5 to 20 hours.

Preferably, in step (1), after the polymerization is finished, the polymerization reaction is terminated by rapidly cooling or adding hydroquinone or methoxyphenol serving as a polymerization inhibitor, and further preferably methoxyphenol. The acid scavenger is preferably triethylamine.

The invention starts from molecular design, modifies the prior FEVE resin, adopts tetrafluoroethylene as raw material, introduces hydrophilic monomers A and B, increases the hydrophilicity of the FEVE resin, and keeps the characteristics of high water resistance, high weather resistance and good glossiness of solvent-based FEVE resin. No emulsifier is used in the whole preparation process. Finally, the aqueous resin dispersion liquid containing low organic solvent is prepared by phase transfer.

The invention has the beneficial effects

The modified FEVE resin aqueous dispersion liquid with low organic solvent content prepared by the invention is water-soluble, but has the characteristics of high water resistance, high weather resistance and good gloss of solvent-based FEVE resin. And no emulsifier is added in the reaction process and the dispersion liquid. The synthesis steps are simple. Due to the introduction of two hydrophilic groups, the pigment has good wettability and dispersibility, and good adhesion to a substrate.

Detailed Description

The present invention is specifically described below with reference to examples in order to facilitate understanding of the present invention by those skilled in the art. It should be particularly noted that the examples are given solely for the purpose of illustration and are not to be construed as limitations on the scope of the invention, as non-essential improvements and modifications to the invention may occur to those skilled in the art, which fall within the scope of the invention as defined by the appended claims. Meanwhile, the raw materials mentioned below are not specified in detail and are all commercial products; the process steps or preparation methods not mentioned in detail are all process steps or preparation methods known to the person skilled in the art. The following parts are parts by weight.