阅读说明：本技术 一种聚酯及其制备方法和含有该聚酯的涂料及其应用 (Polyester and preparation method thereof, coating containing polyester and application of coating ) 是由 虞明东 蒋天龙 于 2020-07-23 设计创作，主要内容包括：本发明公开了一种聚酯及其制备方法和含有该聚酯的涂料及其应用,涉及涂料技术领域；10-20％摩尔含量的2-亚甲基-4-苯基-1,3-二氧戊环、10-20％摩尔含量的2-亚甲基-1,3-二氧环庚烷、20-40％摩尔含量的3,3,3’,3’-四甲基螺环二酚开环反应得到端羟基的中间体,然后再与20-30％摩尔含量的二元羧酸和15-30％摩尔含量的二元醇去反应得到聚酯树脂。再用该树脂复配得到涂料用于金属涂层,本发明的产品具有很好的金属附着力以及优异的抗性,同时可加工性能突出。(The invention discloses polyester, a preparation method thereof, a coating containing the polyester and an application thereof, relating to the technical field of coatings; 10-20% of 2-methylene-4-phenyl-1, 3-dioxolane, 10-20% of 2-methylene-1, 3-dioxepane and 20-40% of 3,3,3',3' -tetramethyl spirodiphenol to obtain intermediate with terminal hydroxyl, and then the intermediate is reacted with 20-30% of dicarboxylic acid and 15-30% of dihydric alcohol to obtain the polyester resin. The resin is compounded to obtain the coating for a metal coating, and the product has good metal adhesion and excellent resistance and has outstanding processability.)

1. The polyester is characterized by comprising the following components in percentage by mol:

2. the polyester according to claim 1, wherein said polybasic acid comprises one or more of terephthalic acid, isophthalic acid, phthalic acid, 2-methyl terephthalic acid, biphenyl dicarboxylic acid, tetrahydronaphthalene dicarboxylic acid, naphthalene dicarboxylic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decane dicarboxylic acid, dodecane dicarboxylic acid, cyclohexane dicarboxylic acid, decahydro naphthalene dicarboxylic acid, trimellitic anhydride, trimellitic acid, trimesic acid, pyromellitic anhydride.

3. The polyester according to claim 1, the polyhydric alcohol comprises one or more of ethylene glycol, 1, 2-propylene glycol, 1, 3-propylene glycol, 1, 4-butanediol, 2-methyl-1, 3-propylene glycol, 1, 5-pentanediol, neopentyl glycol, 1, 6-hexanediol, 3-methyl-1, 5-pentanediol, 1, 9-nonanediol, 2-ethyl-2-butyl-1, 3-propanediol, neopentyl glycol hydroxypivalate, dimethylolheptane, 2, 4-trimethyl-1, 3-pentanediol, 1, 4-cyclohexanediol, 1, 4-cyclohexanedimethanol, tricyclodecanediol, tricyclodecanedimethanol, and spiroglycol.

4. The polyester as claimed in claim 1, wherein the polyester has a number average molecular weight of 5000-25000 and a glass transition temperature of 70-120 ℃.

5. A method for preparing the polyester according to any one of claims 1 to 4, comprising the steps of:

A. putting 2-methylene-4-phenyl-1, 3-dioxolane, 2-methylene-1, 3-dioxepane and 3,3,3',3' -tetramethyl spirodiphenol into a reaction kettle according to a proportion, and adding a catalyst K₂CO₃Stirring and heating under the protection of nitrogen, and reacting at 160-180 ℃ to obtain a hydroxyl-terminated intermediate;

B. adding polybasic acid, polyhydric alcohol and the catalyst in the step B in proportion into the hydroxyl-terminated intermediate, and heating to the temperature of 220-240 ℃ under the protection of nitrogen to perform esterification reaction;

C. the required polyester is obtained by carrying out the reduced pressure polycondensation reaction at the temperature of 250 ℃ and 280 ℃.

6. The method for producing polyester according to claim 5, wherein K is₂CO₃The addition amount of (B) is 100-500ppm of the feeding quality of the step A.

7. The method for preparing polyester according to claim 5, wherein the catalyst in step B is at least one selected from the group consisting of Ti, Sn, Sb, Zn, Al, Mg and their compounds, and the amount thereof added is 700ppm based on the total amount of the charge.

8. A coating comprising the polyester of any one of claims 1 to 4 and a coating additive.

9. The coating of claim 8, wherein the coating additives comprise one or more of curing agents, leveling agents, matting agents, pigment wetting agents, dispersants, pigments, fillers, defoamers, adhesion promoters.

10. Use of the coating according to claim 8 for coating the interior of cans.

Technical Field

The invention relates to the technical field of coatings, in particular to polyester and a preparation method thereof, a coating containing the polyester and application thereof, and especially relates to polyester with high resistance and metal adhesion, a preparation method thereof, a coating containing the polyester and application thereof.

Background

With the gradual improvement of living standard of people, more and more people seek high-quality life, and the food safety problem is particularly emphasized, so that the food safety is naturally the topic with worldwide challenge and public health concern at present.

At present, the inner coating of the metal can for food in China mainly uses epoxy resin and organosol resin, and is commonly used for protecting the metal can from being corroded by contents, so that heavy metal in the metal can is prevented from migrating to food, and the quality guarantee period is prolonged.

Chinese, patent publication No. CN1260818A, discloses a can and coil coating resin using a mixture of at least 2 polyesters and a solvent, wherein at least one of the polyesters has a glass transition temperature above 45 degrees. The acid resistance of the product is to be improved.

The two most common materials are epoxy-phenolic resins and vinyl organosol resins. Epoxy-phenolic resin systems are now largely restricted to use in can interiors due to migration problems with bisphenol a, a potentially health-affecting substance. However, the vinyl resin has problems in adhesion to metals and introduction of an intractable substance during the preparation process.

Disclosure of Invention

In order to overcome the defects and shortcomings in the prior art, the invention aims to provide a polyester, a preparation method thereof, a coating containing the polyester and application thereof.

The purpose of the invention is realized by the following technical scheme: the polyester comprises the following components in percentage by mol:

the inventor finds that the hardness and the resistance can be influenced if the proportion of the 2-methylene-4-phenyl-1, 3-dioxolane is small; if the content is high, the solubility and adhesion flexibility are reduced; the flexibility is reduced, the adhesive force is reduced, the content is high, and the resistance is reduced when the content of the 2-methylene-1, 3-dioxepane is low; the resistance is reduced when the content of the 3,3,3',3' -tetramethyl spiro diphenol is low, and the flexible wire is deteriorated when the content is high.

Preferably, the polybasic acid comprises one or more of terephthalic acid, isophthalic acid, phthalic acid, 2-methyl terephthalic acid, biphenyl dicarboxylic acid, tetrahydronaphthalene dicarboxylic acid, naphthalene dicarboxylic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, decane dicarboxylic acid, dodecane dicarboxylic acid, cyclohexane dicarboxylic acid, decahydronaphthalene dicarboxylic acid, trimellitic anhydride, trimellitic acid, trimesic acid, pyromellitic anhydride.

Preferably, the polyol comprises one or more of ethylene glycol, 1, 2-propanediol, 1, 3-propanediol, 1, 4-butanediol, 2-methyl-1, 3-propanediol, 1, 5-pentanediol, neopentyl glycol, 1, 6-hexanediol, 3-methyl-1, 5-pentanediol, 1, 9-nonanediol, 2-ethyl-2-butyl-1, 3-propanediol, neopentyl glycol hydroxypivalate, dimethylolheptane, 2, 4-trimethyl-1, 3-pentanediol, 1, 4-cyclohexanediol, 1, 4-cyclohexanedimethanol, tricyclodecanediol, tricyclodecanedimethanol, spiroglycol.

Preferably, the number average molecular weight of the polyester is 5000-.

A preparation method of the polyester comprises the following steps:

A. putting 2-methylene-4-phenyl-1, 3-dioxolane, 2-methylene-1, 3-dioxepane and 3,3,3',3' -tetramethyl spirodiphenol into a reaction kettle according to a proportion, and adding a catalyst K₂CO₃Stirring and heating under the protection of nitrogen, and reacting at 160-180 ℃ to obtain a hydroxyl-terminated intermediate;

B. after the by-product in the step A reaches a theoretical value, proportionally adding polybasic acid, polyhydric alcohol and the catalyst in the step B into the intermediate of the terminal hydroxyl group, and heating to the temperature of 220-240 ℃ under the protection of nitrogen to perform esterification reaction;

C. after the byproduct of the esterification reaction reaches a theoretical value, the required polyester is obtained by carrying out the decompression polycondensation reaction at the temperature of 250-280 ℃.

Preferably, the 2-methylene-4-phenyl-1, 3-dioxolane in the step A accounts for 10-20% of the total molar content of the monomers fed in the step A; the 2-methylene-1, 3-dioxepane accounts for 10-20% of the total molar content of the monomers fed in the step A; and the 3,3,3',3' -tetramethyl spiro diphenol accounts for 20-40% of the total molar content of the monomers fed in the step A.

Preferably, said K₂CO₃The addition amount of (B) is 100-500ppm of the feeding quality of the step A.

Preferably, the catalyst in the step B is at least one selected from titanium, tin, antimony, zinc, aluminum, magnesium and compounds thereof, and the addition amount of the catalyst is 100-700ppm of the total feeding mass.

A coating comprising said polyester, a coating additive; the paint additive comprises one or more of a curing agent, a flatting agent, a pigment wetting agent, a dispersing agent, a pigment, a filler, a defoaming agent and an adhesion promoter.

The use of said coating material, characterized in that it is applied in can interiors.

In summary, compared with the prior art, the invention has the following beneficial effects:

(1) the main chain of the polyester prepared by the method contains a plurality of monomers with polycyclic structures, so that the polyester has great steric hindrance effect, ester bonds are protected, and the resistance is improved. The hardness and the strength of the coating can be greatly improved;

(2) meanwhile, a plurality of side chains are arranged on the polycyclic structure, so that the coating has better flexibility;

(3) the ester bond of the polyester can have good adhesive force to the metal base material, so that the performance of the final product is further improved.

Detailed Description

The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, which ranges of values are to be considered as specifically disclosed herein, the invention is described in detail below with reference to specific examples: