阅读说明：本技术 一种提高镀锌件附着力的户外粉末涂料用聚酯树脂及其制备方法、含该聚酯树脂的粉末涂料 (Polyester resin for outdoor powder coating for improving adhesion of galvanized part, preparation method of polyester resin and powder coating containing polyester resin ) 是由 陆言球 李娟� 于 2020-07-13 设计创作，主要内容包括：本发明公开了一种提高镀锌件附着力的户外粉末涂料用聚酯树脂及其制备方法、含该聚酯树脂的粉末涂料,所述聚酯树脂酸值为28-32mgKOH/g,玻璃化转变温度为60-62℃,200℃下粘度为5000-6500mpa.s,平均支化度为2.1～2.4；所述聚酯树脂由以下重量份的组分组成：二元醇37～40份、多元醇0.5～2.5份、二元酸45～55份、酸解剂5～15份、助剂0.6份。本发明中的聚酯树脂用于制作镀锌件用户外粉末涂料,相较现有普通聚酯制作的粉末涂料应用于镀锌件具有更大的附着力。(The invention discloses a polyester resin for outdoor powder coating for improving adhesion of galvanized parts, a preparation method thereof and a powder coating containing the polyester resin, wherein the acid value of the polyester resin is 28-32mgKOH/g, the glass transition temperature is 60-62 ℃, the viscosity is 5000-6500mpa.s at 200 ℃, and the average branching degree is 2.1-2.4; the polyester resin comprises the following components in parts by weight: 37-40 parts of dihydric alcohol, 0.5-2.5 parts of polyhydric alcohol, 45-55 parts of dibasic acid, 5-15 parts of acidolysis agent and 0.6 part of auxiliary agent. The polyester resin is used for preparing the powder coating outside the galvanized part, and has larger adhesive force when being applied to the galvanized part compared with the powder coating prepared from the conventional common polyester.)

1. The polyester resin for the outdoor powder coating for improving the adhesion of galvanized parts is characterized by comprising the following components in parts by weight: the acid value of the polyester resin is 28-32mgKOH/g, the glass transition temperature is 60-62 ℃, the viscosity is 5000-; the polyester resin comprises the following components in parts by weight: 37-40 parts of dihydric alcohol, 0.5-2.5 parts of polyhydric alcohol, 45-55 parts of dibasic acid, 5-15 parts of acidolysis agent and 0.6 part of auxiliary agent.

2. The polyester resin for outdoor powder coating for improving adhesion of galvanized parts according to claim 1, characterized in that: the dihydric alcohol is one or a mixture of more of neopentyl glycol, ethylene glycol and methyl propylene glycol.

3. The polyester resin for outdoor powder coating for improving adhesion of galvanized parts according to claim 1, characterized in that: the polyalcohol is one or a mixture of two of trimethylolpropane and pentaerythritol.

4. The polyester resin for outdoor powder coating for improving adhesion of galvanized parts according to claim 1, characterized in that: the dibasic acid is one or a mixture of more of terephthalic acid, isophthalic acid and adipic acid.

5. The polyester resin for outdoor powder coating for improving adhesion of galvanized parts according to claim 1, characterized in that: the acidolysis agent is one or a mixture of isophthalic acid and adipic acid.

6. The polyester resin for outdoor powder coating for improving adhesion of galvanized parts according to claim 1, characterized in that: the auxiliary agent comprises a catalyst and an antioxidant; the catalyst is monobutyl tin oxide, and the antioxidant is a mixture of triphenyl phosphite, tris (2, 4-di-tert-butylphenyl) phosphite and pentaerythritol tetrapropionate.

7. The polyester resin for outdoor powder coating for improving the adhesion of galvanized parts according to any one of claims 1 to 6, characterized in that: the polyester resin comprises the following components in parts by weight:

neopentyl glycol: 29-40 parts;

ethylene glycol: 0-5 parts;

methyl propylene glycol: 0-3 parts of a solvent;

trimethylolpropane: 0.5-2.5 parts;

pentaerythritol: 0-0.5 part;

terephthalic acid: 35-55 parts of a solvent;

isophthalic acid: 0-8 parts of a solvent;

adipic acid: 0-2 parts of a solvent;

acid hydrolysis agent isophthalic acid: 3-15 parts;

acid hydrolysis agent adipic acid: 0-2 parts of a solvent;

catalyst monobutyl tin oxide: 0.1 part;

antioxidant triphenyl phosphite: 0.1 part;

antioxidant tris (2, 4-di-tert-butylphenyl) phosphite: 0.2 part;

antioxidant pentaerythritol tetrapropionate: 0.2 part.

8. A method for preparing the polyester resin according to any one of claims 1 to 7, wherein: the method comprises the following steps:

adding dihydric alcohol, polyhydric alcohol and a catalyst into a reactor in a nitrogen atmosphere, heating to 130 ℃, adding dibasic acid, stirring uniformly, heating to 180 ℃ to start reaction, heating to 250 ℃ at the speed of 10-15 ℃/h, preserving heat at the temperature until a reaction system is clear, reducing the temperature of the reaction system to 220 ℃, adding an acidolysis agent and antioxidant triphenyl phosphite, heating to 240 ℃, preserving heat for 2h, and continuing to react for 2-4 h under the condition that the vacuum degree is-0.09 to-0.099 MPa; sampling and analyzing acid value and viscosity, wherein: controlling the acid value to be 28-32mg KOH/g, controlling the viscosity to be 5000-6500mpa.s at 200 ℃, adding antioxidant tris (2, 4-di-tert-butylphenyl) phosphite and antioxidant pentaerythritol tetrapropionate after the acid value and the viscosity are reached, stirring for 0.5h, and discharging.

9. A powder coating based on the polyester resin of any of claims 1 to 7, characterized in that: the powder coating comprises the following components in parts by weight:

58 parts of polyester resin;

triglycidyl isocyanurate: 2.4 parts;

18 parts of titanium dioxide;

19.2 parts of barium sulfate;

1 part of a leveling agent;

1 part of a brightener;

0.4 part of benzoin.

10. The powder coating according to claim 9, characterized in that: the triglycidyl isocyanurate is beta-hydroxyalkyl amide, the flatting agent is flatting agent GLP503/588, the brightener is accelerator BLC701, and the benzoin is benzoin ketone benzil.

Technical Field

The invention belongs to the technical field of polyester resin for powder coating, and particularly relates to polyester resin for outdoor powder coating for improving the adhesion of galvanized parts, a preparation method of the polyester resin, and powder coating containing the polyester resin.

Background

Powder coatings are widely used for decoration and protection of base materials such as household appliances, building materials, metal members and the like. The powder coating is solid powder and does not contain organic solvent, so that the powder coating does not discharge any VOC in construction, can be recycled, has the characteristics of harmlessness, resource saving, environmental protection and the like, and gradually expands the application field of the powder coating along with the continuous restriction of the country on VOC discharge.

Along with the development of highways, the powder coating spraying of the highway guardrails is more and more extensive, and because the highway guardrails are mostly galvanized workpieces, and the problem of low film adhesion force generally exists after the sprayed powder coating of the galvanized workpieces is formed into films, the coating of the galvanized workpieces is greatly disturbed.

At present, after the powder coating prepared by common polyester resin is sprayed on a galvanized part, the adhesion of the coating is poor, which is mainly caused by poor coupling force between the powder coating and the galvanized part, so that the coating is easy to break or fall off in different degrees, the affinity of the polyester resin for the powder coating and the galvanized part is improved, and the adhesion of the coating can be improved.

Disclosure of Invention

The invention provides polyester resin for outdoor powder coating for improving adhesion of galvanized parts, a preparation method thereof and powder coating containing the polyester resin.

In order to achieve the purpose, the invention adopts the technical scheme that:

the polyester resin for the outdoor powder coating for improving the adhesion of galvanized parts has the acid value of 28-32mgKOH/g, the glass transition temperature of 60-62 ℃, the viscosity of 5000-6500mpa.s at 200 ℃ and the average branching degree of 2.1-2.4; the polyester resin comprises the following components in parts by weight: 37-40 parts of dihydric alcohol, 0.5-2.5 parts of polyhydric alcohol, 45-55 parts of dibasic acid, 5-15 parts of acidolysis agent and 0.6 part of auxiliary agent.

Preferably, the dihydric alcohol is one or a mixture of neopentyl glycol, ethylene glycol and methyl propylene glycol.

Preferably, the polyalcohol is one or a mixture of two of trimethylolpropane and pentaerythritol.

Preferably, the dibasic acid is one or a mixture of more of terephthalic acid, isophthalic acid and adipic acid.

Preferably, the acidolysis agent is one or a mixture of isophthalic acid and adipic acid.

Preferably, the auxiliary agent comprises a catalyst and an antioxidant; the catalyst is monobutyl tin oxide, and the antioxidant is a mixture of triphenyl phosphite, tris (2, 4-di-tert-butylphenyl) phosphite and pentaerythritol tetrapropionate.

Preferably, the composition comprises the following components in parts by weight:

neopentyl glycol: 29-40 parts;

ethylene glycol: 0-5 parts;

methyl propylene glycol: 0-3 parts of a solvent;

trimethylolpropane: 0.5-2.5 parts;

pentaerythritol: 0-0.5 part;

terephthalic acid: 35-55 parts of a solvent;

isophthalic acid: 0-8 parts of a solvent;

adipic acid: 0-2 parts of a solvent;

acid hydrolysis agent isophthalic acid: 3-15 parts;

acid hydrolysis agent adipic acid: 0-2 parts of a solvent;

catalyst monobutyl tin oxide: 0.1 part;

antioxidant triphenyl phosphite: 0.1 part;

antioxidant tris (2, 4-di-tert-butylphenyl) phosphite: 0.2 part;

antioxidant pentaerythritol tetrapropionate: 0.2 part.

A preparation method of polyester resin comprises the following steps:

adding dihydric alcohol, polyhydric alcohol and a catalyst into a reactor in a nitrogen atmosphere, heating to 130 ℃, adding dibasic acid, stirring uniformly, heating to 180 ℃ to start reaction, heating to 250 ℃ at the speed of 10-15 ℃/h, preserving heat at the temperature until a reaction system is clear, reducing the temperature of the reaction system to 220 ℃, adding an acidolysis agent and antioxidant triphenyl phosphite, heating to 240 ℃, preserving heat for 2h, and continuing to react for 2-4 h under the condition that the vacuum degree is-0.09 to-0.099 MPa; sampling and analyzing acid value and viscosity, wherein: controlling the acid value to be 28-32mg KOH/g, controlling the viscosity to be 5000-6500mpa.s at 200 ℃, adding antioxidant tris (2, 4-di-tert-butylphenyl) phosphite and antioxidant pentaerythritol tetrapropionate after the acid value and the viscosity are reached, stirring for 0.5h, and discharging.

The powder coating based on the polyester resin is composed of the following components in parts by weight:

58 parts of polyester resin;

triglycidyl isocyanurate: 2.4 parts;

18 parts of titanium dioxide;

19.2 parts of barium sulfate;

1 part of a leveling agent;

1 part of a brightener;

0.4 part of benzoin.

Preferably, the triglycidyl isocyanurate is beta-hydroxyalkyl amide, the leveling agent is a leveling agent GLP503/588, the brightener is an accelerator BLC701, and the benzoin is benzoin ketone.

Has the advantages that: compared with the prior art, the preparation of the polyester resin selects different amounts of the polyhydric alcohols, so that a certain amount of hydroxyl groups which do not participate in subsequent reaction are provided for the polyester resin, and after the powder coating prepared by the preparation of the polyester resin is coated on the surface of a galvanized workpiece, the hydroxyl groups have hydrophilicity and play a role in coupling between the coating and the workpiece.

The powder coating for spraying the galvanized part, which is prepared from the polyester resin, has the advantage that the adhesive force of a coating film is greatly improved compared with that of the conventional hot common powder coating after the galvanized part is sprayed.

Detailed Description

The present invention will be further described with reference to the following examples.