阅读说明：本技术 一种聚酯树脂及其制备方法与应用 (Polyester resin and preparation method and application thereof ) 是由 虞明东 赵天豪 余德水 于 2021-08-09 设计创作，主要内容包括：本发明提供了一种聚酯树脂及其制备方法与应用,所述聚酯树脂由包括二元羧酸、双酚酸、二元醇、催化剂的原料通过逐步聚合法制备而得；所述聚酯树脂数均分子量为25000-40000,玻璃化转变温度为10-30℃,羟值2-10mgKOH/g；本发明中的聚酯树脂通过分布投料的方法合成,将双酚酸保留在聚酯链的端头,在树脂的端头含有苯环以及多个羟基,与固化剂反应后,能形成局部硬段,与聚酯主长链相对比较软,两者相互作用,弹性大大增加。相比于普通树脂而言,双酚酸的结构特殊,固化后能形成与PI膜能形成结构近似的官能团,增加其在PI膜等基材的附着力的同时兼顾耐溶剂性能与柔韧性的平衡。(The invention provides a polyester resin and a preparation method and application thereof, wherein the polyester resin is prepared from raw materials comprising dicarboxylic acid, diphenolic acid, dihydric alcohol and a catalyst by a step-by-step polymerization method; the number average molecular weight of the polyester resin is 25000-40000, the glass transition temperature is 10-30 ℃, and the hydroxyl value is 2-10 mgKOH/g; the polyester resin is synthesized by a distributed feeding method, diphenolic acid is kept at the end of a polyester chain, the end of the resin contains benzene rings and a plurality of hydroxyl groups, and after the resin reacts with a curing agent, a local hard segment can be formed and is relatively soft with a main polyester long chain, and the elasticity is greatly increased due to the interaction of the resin and the main polyester long chain. Compared with common resin, the diphenolic acid has a special structure, can form a functional group similar to the structure formed by a PI film after being cured, increases the adhesive force of the PI film and other base materials, and simultaneously considers the balance of solvent resistance and flexibility.)

1. The polyester resin is characterized by being prepared from raw materials comprising dicarboxylic acid, diphenolic acid, dihydric alcohol and a catalyst by a step-by-step polymerization method; the polyester resin has the number average molecular weight of 25000-40000, the glass transition temperature of 10-30 ℃ and the hydroxyl value of 2-10 mgKOH/g.

2. The polyester resin according to claim 1, wherein the molar content of the diol is 1.2 to 1.7 times the molar content of the dicarboxylic acid.

3. The polyester resin of claim 1, wherein the diphenolic acid is present in a molar amount of 5% to 15% of the dicarboxylic acid.

4. The polyester resin of claim 1, wherein the dicarboxylic acid comprises one or more of terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, phthalic acid, adipic acid, azelaic acid, sebacic acid, 1, 4-cyclohexanedicarboxylic acid, maleic acid, fumaric acid, itaconic acid.

5. The polyester resin according to claim 1, wherein the dicarboxylic acid is terephthalic acid, isophthalic acid, and adipic acid; or terephthalic acid, isophthalic acid and sebacic acid; or terephthalic acid, phthalic acid and sebacic acid.

6. The polyester resin according to claim 1, wherein the diol comprises one or more of ethylene glycol, 1, 2-propanediol, 1, 4-butanediol, 1, 3-propanediol, hexanediol, 1, 4-cyclohexanedimethanol, neopentyl glycol, 1, 6-hexanediol, isosorbide, tricyclodecanedimethanol, hydrogenated bisphenol a, and bisphenol a polyoxyethylene ether.

7. The polyester resin of claim 1, wherein the catalyst comprises one or more of tetrabutyl titanate, isopropyl titanate, zinc acetate, cobalt acetate, manganese acetate, antimony trioxide, antimony acetate, ethylene glycol antimony.

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

A. putting dicarboxylic acid, diol and catalyst into a reaction kettle; under the protection of nitrogen, heating to the temperature of 220-240 ℃ for esterification reaction;

B. and (3) when the byproduct of the esterification reaction in the step A reaches a theoretical value, adding diphenolic acid, maintaining the temperature at 220-240 ℃, continuing the reaction for 1-3h, and then performing a reduced pressure reaction to obtain the polyester resin.

9. Use of a polyester resin according to any one of claims 1 to 7 in the preparation of a flexible ink.

10. Use according to claim 9, characterised in that the ink comprises at least one ink additive selected from levelling agents, pigment wetting and dispersing agents, pigments, fillers, antifoaming agents, adhesion promoters.

Technical Field

The invention relates to the field of polymer synthesis, in particular to polyester resin and a preparation method and application thereof, and especially relates to polyester resin and a preparation method and application thereof in flexible ink.

Background

The use of flexible inks today is mostly concentrated in the field of packaging printing, accounting for about 85%, such as various plastic films, metal foils, paper boards, decorative packaging paper, glass cloth, kraft paper, etc. The method is widely applied to multiple industries such as food, medicine, textile, building and the like. Because the base material is soft and has various use scenes and needs to be bent frequently, the requirements on weather resistance, flexibility, adhesive force and the like of the printing ink are high.

At present, the bonding material for the ink in China mainly takes acrylic acid, polyester and polyurethane as main materials, is used in the aspect of flexible ink, and has a plurality of defects of the existing product such as: for poor adhesion to the substrate, the binder resin is hard to cause poor flexibility, or the resin is too soft, the ink is displaced, and the like, and improvement is urgently required.

In the prior patent CN102532996B, a flexible ink for a white cover film of an LED soft light slat is disclosed, and a straight-chain type organic silicon modified saturated polyester or a branched-chain type organic silicon modified saturated polyester can achieve good bending resistance, and is good in wiping resistance and high temperature resistance. However, the silicone-modified polyester is easily self-polymerized by the modified silicone, and phase separation from the resin may occur to deteriorate the resin properties.

In the prior patent CN110511610A, a novel LED coating varnish ink and a preparation method thereof are disclosed, wherein resin, filler, auxiliary agent, active monomer and the like are used as raw materials, and LED cured ink is prepared through steps of dispersing, grinding and the like, wherein epoxy acrylic resin is bisphenol a type epoxy acrylate as an ink main body, and the curing rate can be improved by mixing with polyester acrylic resin, so that rapid curing is realized, and the adhesive force of the ink to plastic or metal substrates is improved. However, the resin used is hard and has poor flexibility, which cannot meet the use requirement of flexible ink.

Disclosure of Invention

In order to overcome the defects and shortcomings in the prior art, the invention aims to provide a polyester resin and a preparation method and application thereof. Compared with common resin, the polyester resin provided by the invention has good adhesive force to a PI film, and the ink layer has good elasticity, so that the use of flexible ink is met.

The purpose of the invention is realized by the following technical scheme:

a polyester resin is prepared from raw materials including dicarboxylic acid, diphenolic acid, dihydric alcohol and a catalyst by a step-by-step polymerization method; the polyester resin has the number average molecular weight of 25000-40000, the glass transition temperature of 10-30 ℃ and the hydroxyl value of 2-10 mgKOH/g.

The number average molecular weight of the polyester resin is 25000-40000, and if the molecular weight of the polyester resin is smaller, the obtained coating has too high crosslinking density, high hardness and serious reduction of adhesive force and flexibility; if the molecular weight is large, the reaction requirement is high, and adverse effects such as degradation yellowing and the like are easy to occur in the preparation process; the glass transition temperature is 10-30 ℃, so that the printing ink has good flexibility and high bendability, the hydroxyl value is 2-10mgKOH/g, the hydroxyl value is related to the number of reaction functional groups, too few crosslinking curing is insufficient, poor solvent resistance is realized, too much molecular weight is reduced, and the flexibility is reduced.

In one embodiment of the present invention, the molar content of the diol is 1.2 to 1.7 times the molar content of the dicarboxylic acid. If the ratio of the molar content of the dihydric alcohol to the molar content of the dicarboxylic acid is less than 1.2 to 1.7 times, the esterification reaction is incomplete, so that the acid value of the product is too high, and the molecular weight cannot reach the expected target; the ratio of the molar content of the dihydric alcohol to the molar content of the dicarboxylic acid is more than 1.2 to 1.7 times, which causes waste of raw materials and energy.

In one embodiment of the present invention, the molar content of the diphenolic acid is 5% to 15% of the molar content of the dicarboxylic acid. If the content is less than 5%, the elastic property is weak, the adhesion force is biased, and the solvent resistance is insufficient; when the amount exceeds 15%, the ink becomes hard and the flexibility becomes poor.

The dicarboxylic acid comprises one or more of terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, phthalic acid, adipic acid, azelaic acid, sebacic acid, 1, 4-cyclohexane dicarboxylic acid, maleic acid, fumaric acid and itaconic acid.

Preferably, the dicarboxylic acids are terephthalic acid, isophthalic acid and adipic acid; or terephthalic acid, isophthalic acid and sebacic acid; or terephthalic acid, phthalic acid and sebacic acid.

The dihydric alcohol comprises one or more of ethylene glycol, 1, 2-propylene glycol, 1, 4-butanediol, 1, 3-propanediol, hexanediol, 1, 4-cyclohexanedimethanol, neopentyl glycol, 1, 6-hexanediol, isosorbide, tricyclodecane dimethanol, hydrogenated bisphenol A, and bisphenol A polyoxyethylene ether.

The catalyst comprises one or more of tetrabutyl titanate, isopropyl titanate, zinc acetate, cobalt acetate, manganese acetate, antimony trioxide, antimony acetate and ethylene glycol antimony.

The preparation method of the polyester resin comprises the following steps:

A. putting dicarboxylic acid, diol and catalyst into a reaction kettle; under the protection of nitrogen, heating to the temperature of 220-240 ℃ for esterification reaction;

B. and (3) when the byproduct of the esterification reaction in the step A reaches a theoretical value, adding diphenolic acid, maintaining the temperature at 220-240 ℃, continuing the reaction for 1-3h, and then performing a reduced pressure reaction to obtain the polyester resin.

Wherein the theoretical value of the reaction in the step A is determined according to the water completely obtained by the reaction of the dibasic acid.

The application of the polyester resin provided by the invention in the preparation of flexible ink also belongs to the protection scope of the invention.

Further, the ink comprises at least one ink additive selected from leveling agents, pigment wetting and dispersing agents, pigments, fillers, antifoaming agents and adhesion promoters.

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

the polyester resin is synthesized by a step-by-step feeding method, diphenolic acid is kept at the end of a polyester chain, the end of the resin contains benzene rings and a plurality of hydroxyl groups, and after the resin reacts with a curing agent, a local hard segment can be formed and is relatively soft with a main polyester long chain, and the elasticity is greatly increased due to the interaction of the resin and the main polyester long chain. Compared with common resin, the diphenolic acid has a special structure, can form a functional group similar to the structure formed by a PI film after being cured, increases the adhesive force of the PI film and other base materials, and simultaneously considers the balance of solvent resistance and flexibility.

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:

example 1

A polyester resin comprising:

wherein the total molar content of the ethylene glycol and the neopentyl glycol is 1.3 times of the total molar content of the terephthalic acid, the isophthalic acid and the adipic acid.

The molar content of the diphenolic acid is 5 percent of the total molar content of the terephthalic acid, the isophthalic acid and the adipic acid.

A polyester resin and a preparation method thereof comprise the following steps: all of the monomers except diphenolic acid and 72g of isopropyl titanate were charged into a reaction vessel, and air was purged with nitrogen gas, and the mixture was stirred and heated to react at 220 ℃. And when the by-product reaches a theoretical value, adding diphenolic acid, maintaining the temperature at 220 ℃ for reaction, reacting for 1.2h, performing reduced pressure polycondensation, stopping the reaction when the reaction temperature reaches 250 ℃ and the end point is reached, introducing nitrogen to remove vacuum, and extruding and discharging.

Example 2

A polyester resin comprising:

wherein the total molar content of the ethylene glycol and the neopentyl glycol is 1.25 times of the total molar content of the terephthalic acid, the isophthalic acid and the adipic acid.

The molar content of the diphenolic acid is 8 percent of the total molar content of the terephthalic acid, the isophthalic acid and the adipic acid.

A polyester resin and a preparation method thereof comprise the following steps: all of the monomers except diphenolic acid and 72g tetrabutyl titanate were put into a reaction vessel, and air was purged with nitrogen gas, and the mixture was stirred and heated to 240 ℃. And when the by-product reaches a theoretical value, adding diphenolic acid, maintaining the temperature at 240 ℃ for reaction, reacting for 1.5h, performing reduced pressure polycondensation, stopping the reaction when the reaction temperature reaches-280 ℃ and the end point is reached, filling nitrogen to remove vacuum, and extruding and discharging.

Example 3

A polyester resin comprising:

wherein the total molar content of the ethylene glycol, the 1, 4-cyclohexanedimethanol is 1.4 times of the total molar content of the terephthalic acid, the isophthalic acid and the sebacic acid.

The molar content of the diphenolic acid is 10 percent of the total molar content of the terephthalic acid, the phthalic acid and the sebacic acid.

A polyester resin and a preparation method thereof comprise the following steps: all of the monomers except diphenolic acid and 72g tetrabutyl titanate were put into a reaction vessel, and air was purged with nitrogen gas, and the mixture was stirred and heated to 220 ℃. And when the by-product reaches a theoretical value, adding diphenolic acid, reacting at 220 ℃ for 2h, carrying out reduced pressure polycondensation, stopping the reaction when the reaction temperature reaches 250 ℃ and the end point is reached, introducing nitrogen to remove vacuum, and extruding and discharging.

Example 4

A polyester resin comprising:

wherein the total molar content of the ethylene glycol and the neopentyl glycol is 1.5 times of the total molar content of the terephthalic acid, the phthalic acid and the sebacic acid.

The molar content of the diphenolic acid is 14 percent of the total molar content of the terephthalic acid, the phthalic acid and the sebacic acid.

A polyester resin and a preparation method thereof comprise the following steps: all of the monomers except diphenolic acid and 72g tetrabutyl titanate were put into a reaction vessel, and air was purged with nitrogen gas, and the mixture was stirred and heated to 240 ℃. And when the by-product reaches a theoretical value, adding diphenolic acid, maintaining the temperature at 240 ℃ for reaction, reacting for 1.5h, performing reduced pressure polycondensation, stopping the reaction when the reaction temperature reaches 280 ℃ and the end point is reached, introducing nitrogen to eliminate vacuum, and extruding and discharging.

Comparative example 1:

a polyester resin and a preparation method thereof comprise the following steps: 37kg of terephthalic acid, 57kg of isophthalic acid, 60kg of adipic acid, 82kg of ethylene glycol, 83kg of neopentyl glycol and 72g of isopropyl titanate were put into a reaction vessel, and air was purged with nitrogen gas, and the mixture was stirred and heated to react at 220 ℃. And when the by-product reaches a theoretical value, carrying out reduced pressure polycondensation, stopping the reaction when the reaction temperature reaches 240 ℃ and the end point is reached, introducing nitrogen to eliminate vacuum, and extruding and discharging.

Comparative example 2:

a polyester resin and a preparation method thereof comprise the following steps: 37kg of terephthalic acid, 57kg of isophthalic acid, 60kg of adipic acid, 82kg of ethylene glycol, 83kg of neopentyl glycol and 72g of isopropyl titanate were put into a reaction vessel, and air was purged with nitrogen gas, and the mixture was stirred and heated to react at 240 ℃. And when the by-product reaches a theoretical value, carrying out reduced pressure polycondensation, stopping the reaction when the reaction temperature reaches 270 ℃ and the end point is reached, introducing nitrogen to eliminate vacuum, and extruding and discharging.

Comparative example 3

Comparative example 3 was fed together and compared to the previous example 1 in steps.

A polyester resin and a preparation method thereof comprise the following steps: the raw materials and the amounts used in example 1 were charged into a reaction vessel together, the air was purged with nitrogen, and the mixture was stirred and heated to react at 220 ℃. And when the by-product reaches a theoretical value, carrying out reduced pressure polycondensation, stopping the reaction when the reaction temperature is 250 ℃ and the end point is reached, introducing nitrogen to eliminate vacuum, and extruding and discharging.

Example 5 Performance testing

This example was conducted to perform a performance test on the products prepared in examples 1 to 4 and comparative examples 1 to 3.

Adding 40kg of mixed solvent of ethyl acetate and DBE (ratio 1:1) into a mixing kettle, adding 20kg of resins of examples 1-4 and comparative example into the mixing kettle respectively under the stirring state, dissolving and uniformly stirring; then adding 20kg of titanium dioxide color paste, 1.5kg of catalyst (NACURE 4046), 1.1kg of flatting agent (BKY016) and 1.5kg of curing agent isocyanate (3300), and uniformly stirring at high speed to obtain the ink for later use.

Preparation of the ink coating:

the prepared example ink and comparative ink were coated on a polyimide film with a 60# wire bar, baked at 180 ℃ for 12min, cooled, and then left to cure at room temperature for one day, and then tested for properties.

Appearance:

the surface condition, glossiness and roughness of the ink layer were observed.

Solvent-resistant wiping:

the surface of the coating was rubbed back and forth linearly with absorbent cotton in one kilogram of butanone, one stroke was counted as 1, and the number of times of rubbing until the substrate was exposed was counted, and more than 50 strokes were counted as more than 50.

And (3) testing the adhesive force:

the adhesion of the ink coating to the substrate was tested using the Baige method and no detachment was noted as being excellent.

Testing the adhesive force after kneading:

and repeatedly rubbing the film layer coated with the ink for 50 times, and testing the adhesive force of the ink coating to the substrate by using a check method, wherein the adhesive force is completely not fallen and is marked as excellent.

Solder yellowing:

and soaking the prepared coating in 300-degree soldering tin liquid for 10s at three continuous intervals. Observe the degree of yellowing

The test results are shown in table 1.

TABLE 1 results of Performance test of examples 1-4 and comparative examples 1-3

Numbering	Appearance of the product	Solvent resistant wipe	Adhesion force	Adhesive force after kneading	Yellow stain
						Example 1	Superior food	50	Superior food	Superior food	Does not turn yellow
Example 2	Superior food	50	Superior food	Superior food	Does not turn yellow
						Example 3	Superior food	50	Superior food	Superior food	Does not turn yellow
Example 4	Superior food	50	Superior food	Superior food	Does not turn yellow
						Comparative example 1	Superior food	20	Good wine	Difference (D)	Slight yellowing
Comparative example 2	Superior food	20	Good wine	Difference (D)	Slight yellowing
						Comparative example 3	Superior food	50	Difference (D)	Difference (D)	Does not turn yellow

Compared with the common resin, the polyester resin disclosed by the invention has the advantages that the appearance adhesive force of the prepared ink on a polyimide film is excellent, and meanwhile, the prepared ink has good flexibility and yellowing resistance, and is very suitable for the use of flexible ink.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.