CN112812724B

CN112812724B - Polyester adhesive and preparation method thereof

Info

Publication number: CN112812724B
Application number: CN202011640292.7A
Authority: CN
Inventors: 刘源; 夏修旸; 何炫辰; 陈洪野; 吴小平
Original assignee: Cybrid Technologies Inc
Current assignee: Cybrid Technologies Inc
Priority date: 2020-12-31
Filing date: 2020-12-31
Publication date: 2022-11-18
Anticipated expiration: 2040-12-31
Also published as: CN112812724A

Abstract

The invention discloses a polyester adhesive and a preparation method thereof. In order to solve the problems that the bonding strength of the existing adhesive to an untreated PET film, a fluorine film or a polyolefin film and other base materials is not high enough and the aging resistance is not enough, the invention provides a polyester adhesive, which comprises 30-45% of polyester, 3-10% of a curing agent and 50-66% of an organic solvent by mass percent; wherein the polyester is polymerized by polyalcohol, dibasic acid and monomer containing hydroxyl, and the alcohol-acid ratio of the polyalcohol to the dibasic acid is 1.1-2.0. The adhesive can be directly used for bonding untreated PET films, fluorine films and polyolefin films, can achieve higher adhesive force, and is simple in construction process. Because the PET does not need to be subjected to surface treatment, the energy and the construction time are effectively saved. The adhesive has the advantages of long storage time, uniform distribution, simple preparation method and wide market prospect.

Description

Polyester adhesive and preparation method thereof

Technical Field

The invention particularly relates to a polyester adhesive and a preparation method thereof.

Background

Currently, a PET film is most commonly used in an adhesive tape, and the PET film is a colorless, transparent and glossy film, has good mechanical properties, electrical properties, optical properties, chemical resistance and the like, and is widely used in various aspects of production and life, including a packaging film, a separation film, a protection film and the like.

However, the PET film without surface treatment has low surface energy and hardness, and poor wear resistance and hygroscopicity, so that the PET film is very unfavorable for adhesive construction. In order to improve the surface energy, the method for carrying out technical treatment on the surface of the PET film comprises the following steps: mechanical treatment is carried out, so that the surface roughness of the PET film is changed, the purpose of increasing the surface adhesion of the PET film is achieved, however, the method influences the gloss and also has adverse influence on the mechanical property of the film; chemical treatment, namely treating the surface of the PET film by using a chemical reagent with oxidizability and corrosiveness, but the method is seriously polluted, and generates metal residues to influence the electrical property of the film; the surface coupling agent treatment, which improves the adhesive force of the film aggregate to the adhesive substance through the amphiphilic chemical substance, has high price and is generally only used for the metal coating process; flame treatment, namely treating the PET film by using high-temperature gas flame to improve the adhesive force of the surface of the film; for the plasma treatment, low-temperature plasma is generally used. Moreover, the treatment methods are time-consuming and energy-consuming, and often have service time limitation, and the treatment effect is weakened or even disappears after half a year of treatment.

Therefore, how to perform adhesive construction on the surface of the untreated PET film is a technical problem which needs to be solved urgently. The common method is to pre-coat a layer of high-wettability coating on the surface of an untreated film and then perform construction, and the coating needs to be performed twice, so that the working procedure is complex. Much research has been conducted in recent years on precoating coatings, and the adhesion properties of polyhydroxylactones and their adhesives have been evaluated in patent US8283435 by robert.s. whitehouse, and in particular untreated PET films have attracted much attention in the industry. The adhesive force to the aggregate is improved by utilizing the active hydroxyl of the polyhydroxy lactone, and the polyhydroxy lactone has very excellent adhesive force both as a hot melt adhesive and a precoating coating. However, this method has not yet achieved sufficient convenience in application to PET films, and other properties such as salt spray resistance and hydrolysis resistance have not been studied.

Disclosure of Invention

The invention aims to provide a polyester adhesive which has good bonding performance to untreated PET films, fluorine films or polyolefin films and other base materials and good ageing resistance.

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

the first aspect of the invention provides a polyester adhesive, which comprises, by mass, 30-45% of polyester, 3-10% of a curing agent, and 50-66% of an organic solvent; the polyester is polymerized by polyalcohol, dibasic acid and lactone and/or lactide, and the alcohol-acid ratio of the polyalcohol to the dibasic acid is 1.1-2.0.

Preferably, the adhesive comprises, by mass, 35% to 45% of polyester, 3% to 5% of a curing agent, and 55% to 62% of an organic solvent.

Preferably, the intrinsic viscosity of the polyester is 0.1-0.6, the acid value is 1-15 mg KOH/g, the hydroxyl value is 5-20 mg KOH/g, and the glass transition temperature is-15-25 ℃.

More preferably, the intrinsic viscosity of the polyester is 0.3 to 0.5, the acid value is 1 to 5mg KOH/g, the hydroxyl value is 10 to 20mg KOH/g, and the glass transition temperature is-5 to 20 DEG C

Preferably, the lactone is one or more of 3-hydroxybutyrolactone, 3-hydroxypentanolactone, 3-hydroxycaprolactone, 4-hydroxypentanolactone, 4-hydroxycaprolactone, 5-hydroxynonalactone, or 6-hydroxyheptalactone.

Preferably, the lactide is one or more of glycolide and lactide

Preferably, the polyol is a combination of one or more of ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, methylpentanediol, pentanediol, heptanediol, octanediol, nonanediol, decanediol, cyclohexanedimethanol, cyclohexanediol, pentaerythritol, glycerol, trimethylolpropane, trimethylolethane, or trimethylolmethane.

Preferably, the dibasic acid is one or more of adipic acid, terephthalic acid, isophthalic acid and sebacic acid;

preferably, the organic solvent is one or more of ethyl acetate, toluene, xylene and butyl acetate.

According to one embodiment, the polyester is prepared by a process comprising: and reacting the polyalcohol, the dibasic acid and the hydroxyl-containing monomer at 200-240 ℃ under the action of a catalyst until the acid value is less than 20mg KOH/g, heating to 240-260 ℃ after stopping the reaction, and stirring and polycondensing under a vacuum condition to obtain the polyester.

Further preferably, the catalyst is one or more of acetate, butyl titanate, isopropyl titanate, titanium amino triethoxide, dibutyltin oxide, antimony trioxide, ethylene glycol antimony, or p-toluenesulfonic acid.

More preferably, the feeding amount of the catalyst is 0.03-0.05% of the total mass of all fed monomers.

Further preferably, the curing agent is an aliphatic polyisocyanate-based curing agent.

More specifically, the curative is Desmodur N3300 from bayer corporation, germany.

Preferably, the polyester adhesive is used for bonding of untreated PET film, fluorine film, or polyolefin film with other substrates including, but not limited to, PET sheet, PC film, PMMA film, or aluminum foil.

The second aspect of the invention also provides a preparation method of the polyester adhesive, which comprises the steps of mixing the polyester, the curing agent and the organic solvent, and uniformly stirring.

More specifically, the preparation method of the polyester adhesive comprises the following steps:

a1, preparing polyester,

a11, putting a polyalcohol monomer, a dibasic acid monomer, lactone and/or lactide and a catalyst into a reaction kettle, and uniformly mixing, wherein the polyalcohol monomer and the dibasic acid monomer are in an alcohol-acid ratio of 1.1-2.0, and the catalyst accounts for 0.03-0.05% of the mass of all the fed monomers;

a12, raising the temperature in the reaction kettle to 200-240 ℃ for raw material esterification reaction, taking the acid value less than 20mg KOH/g as a reaction end point, raising the temperature to 240-260 ℃ after the reaction is finished, and carrying out polycondensation stirring under a vacuum condition to obtain polyester;

and A2, adding the materials in the A1 into a solvent, stirring and mixing, and adding a curing agent to finally obtain the polyester adhesive.

The third aspect of the invention also provides an application of the polyester adhesive in a solar cell backboard.

Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages:

the adhesive can be directly used for bonding untreated PET films, fluorine films and polyolefin films on the premise of not adding an adhesion promoting assistant, can achieve higher adhesion, and is simple in construction process. Because the PET does not need to be subjected to surface treatment, the energy and the construction time are effectively saved. The adhesive has the advantages of long storage time, uniform distribution, simple preparation method and low raw material cost, thereby having wide market prospect.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following detailed description, but those skilled in the art will understand that the following described examples are some, not all, of the examples of the present invention, and are only used for illustrating the present invention, and should not be construed as limiting the scope of the present invention. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

Example 1

First, the preparation of the polyester is carried out:

40kg of adipic acid, 80kg of terephthalic acid, 80kg of isophthalic acid, 70kg of ethylene glycol, 80kg of neopentyl glycol, 35kg of 3-hydroxypentanolactone and 200g of tetrabutyl titanate were put into a reaction vessel. Displacing exhausted air with nitrogen, stirring and heating to 200-240 ℃ for reaction until the acid value is less than 20mg KOH/g, after the reaction is finished, heating to 240-260 ℃, carrying out polycondensation and stirring to the key point under the vacuum condition, introducing nitrogen to eliminate vacuum, slicing and discharging to obtain the polyester.

The obtained polyester: the intrinsic viscosity I.V. was 0.44, the glass transition temperature Tg was 12 ℃, the acid value A.V. was 2mgKOH/g, and the hydroxyl value OH.V. was 12mgKOH/g.

Then 250kg of the prepared polyester and 25kg of mixed curing agent Desmodur N3300 are stirred at high speed and mixed evenly; ethyl acetate was added to dilute to 40% solids and the resulting solution was used as a polyester binder.

Example 2

First, the preparation of the polyester is carried out:

75kg of adipic acid, 40kg of terephthalic acid, 85kg of isophthalic acid, 80kg of ethylene glycol, 100kg of neopentyl glycol, 25kg of 3-hydroxycaprolactone, 15kg of glycolic acid and 200g of tetrabutyltitanate are placed in a reaction vessel. Displacing exhausted air with nitrogen, stirring and heating to 200-240 ℃ for reaction until the acid value is less than 20mg KOH/g, after the reaction is finished, heating to 240-260 ℃, carrying out polycondensation and stirring to the key point under the vacuum condition, introducing nitrogen to eliminate vacuum, slicing and discharging to obtain the polyester.

The obtained polyester: the intrinsic viscosity I.V. was 0.35, the glass transition temperature Tg was 2 ℃, the acid value A.V. was 2mgKOH/g, and the hydroxyl value OH.V. was 16mgKOH/g.

Then 250kg of the prepared polyester and 30kg of mixed curing agent Desmodur N3300 are stirred at high speed and mixed evenly; ethyl acetate was added to dilute to a solid content of 40%, and the resulting solution was used as a polyester binder.

Example 3

First, the preparation of the polyester was carried out:

50kg of sebacic acid, 85kg of terephthalic acid, 85kg of isophthalic acid, 60kg of ethylene glycol, 100kg of neopentyl glycol, 45kg of 4-hydroxypentanolide and 200g of tetrabutyltitanate were placed in a reaction vessel. Displacing exhausted air with nitrogen, stirring and heating to 200-240 ℃ for reaction until the acid value is less than 20mg KOH/g, taking the end point as the end point, heating to 240-260 ℃ after the reaction is finished, carrying out polycondensation and stirring to the key point under the vacuum condition, filling nitrogen to eliminate vacuum, slicing and discharging to obtain the polyester.

The obtained polyester: the intrinsic viscosity I.V. was 0.41, the glass transition temperature Tg was 7 ℃, the acid value A.V. was 2mg KOH/g and the hydroxyl value OH.V. was 12mg KOH/g.

Example 4

First, the preparation of the polyester was carried out:

50kg of sebacic acid, 40kg of terephthalic acid, 80kg of isophthalic acid, 60kg of ethylene glycol, 60kg of 1, 2-propanediol, 40kg of 4-hydroxycaprolactone and 200g of tetrabutyl titanate were put into a reaction vessel. Displacing exhausted air with nitrogen, stirring and heating to 200-240 ℃ for reaction until the acid value is less than 20mg KOH/g, after the reaction is finished, heating to 240-260 ℃, carrying out polycondensation and stirring to the key point under the vacuum condition, introducing nitrogen to eliminate vacuum, slicing and discharging to obtain the polyester.

The obtained polyester: the intrinsic viscosity I.V. was 0.40, the glass transition temperature Tg was 10 ℃, the acid value A.V. was 2mg KOH/g and the hydroxyl value OH.V. was 13mg KOH/g.

Comparative example 1

First, the preparation of the polyester is carried out:

40kg of adipic acid, 80kg of terephthalic acid, 80kg of isophthalic acid, 70kg of ethylene glycol, 80kg of neopentyl glycol and 200g of tetrabutyl titanate were placed in a reaction vessel. Displacing exhausted air with nitrogen, stirring and heating to 200-240 ℃ for reaction until the acid value is less than 20mg KOH/g, after the reaction is finished, heating to 240-260 ℃, carrying out polycondensation and stirring to the key point under the vacuum condition, introducing nitrogen to eliminate vacuum, slicing and discharging to obtain the polyester.

The obtained polyester: the intrinsic viscosity I.V. was 0.44, the glass transition temperature Tg was 11 ℃, the acid value A.V. was 2mgKOH/g, and the hydroxyl value OH.V. was 12mgKOH/g.

Then 250kg of the prepared polyester and 25kg of mixed curing agent Desmodur N3300 are stirred at high speed and mixed evenly; ethyl acetate was added to dilute to a solid content of 40%, and the resulting solution was used as a polyester binder.

Comparative example 2

First, the preparation of the polyester is carried out:

75kg of adipic acid, 40kg of terephthalic acid, 85kg of isophthalic acid, 80kg of ethylene glycol, 100kg of neopentyl glycol and 200g of tetrabutyltitanate were placed in a reaction vessel. Displacing exhausted air with nitrogen, stirring and heating to 200-240 ℃ for reaction until the acid value is less than 20mg KOH/g, taking the end point as the end point, heating to 240-260 ℃ after the reaction is finished, carrying out polycondensation and stirring to the key point under the vacuum condition, filling nitrogen to eliminate vacuum, slicing and discharging to obtain the polyester.

The obtained polyester: the intrinsic viscosity I.V. was 0.35, the glass transition temperature Tg was 4 ℃, the acid value A.V. was 2mgKOH/g, and the hydroxyl value OH.V. was 16mgKOH/g.

Then 250kg of the polyester prepared in the above and 30kg of mixed curing agent Desmodur N3300 are stirred at high speed and mixed evenly; ethyl acetate was added to dilute to 40% solids and the resulting solution was used as a polyester binder.

Comparative example 3

First, the preparation of the polyester is carried out:

50kg of sebacic acid, 85kg of terephthalic acid, 85kg of isophthalic acid, 60kg of ethylene glycol, 100kg of neopentyl glycol and 200g of tetrabutyl titanate were placed in a reaction vessel. Displacing exhausted air with nitrogen, stirring and heating to 200-240 ℃ for reaction until the acid value is less than 20mg KOH/g, after the reaction is finished, heating to 240-260 ℃, carrying out polycondensation and stirring to the key point under the vacuum condition, introducing nitrogen to eliminate vacuum, slicing and discharging to obtain the polyester.

The obtained polyester: the intrinsic viscosity I.V. was 0.41, the glass transition temperature Tg was 9 ℃, the acid value A.V. was 2mg KOH/g and the hydroxyl value OH.V. was 12mg KOH/g.

Comparative example 4

50kg of sebacic acid, 40kg of terephthalic acid, 80kg of isophthalic acid, 60kg of ethylene glycol, 60kg of 1, 2-propanediol, and 200g of tetrabutyltitanate were put into a reaction vessel. Displacing exhausted air with nitrogen, stirring and heating to 200-240 ℃ for reaction until the acid value is less than 20mg KOH/g, after the reaction is finished, heating to 240-260 ℃, carrying out polycondensation and stirring to the key point under the vacuum condition, introducing nitrogen to eliminate vacuum, slicing and discharging to obtain the polyester.

The obtained polyester: the intrinsic viscosity I.V. was 0.40, the glass transition temperature Tg was 13 ℃, the acid value A.V. was 2mg KOH/g and the hydroxyl value OH.V. was 13mg KOH/g.

Comparative example 5

Example 1 of CN106905909 a:

40kg of neopentyl glycol, 43kg of terephthalic acid, 40kg of isophthalic acid and 150g of tetrabutyltitanate were put into a reaction vessel. Displacing exhausted air with nitrogen, stirring and heating to 200-240 ℃ for reaction until the acid value is less than 30mg KOH/g, after the reaction is finished, heating to 240-260 ℃, carrying out polycondensation and stirring for 30min under the vacuum condition, introducing nitrogen to remove vacuum, extruding and discharging to obtain the polyester.

The obtained polyester: the intrinsic viscosity I.V. was 0.12, the glass transition temperature Tg was 40 ℃, the acid value A.V. was 7mg KOH/g and the hydroxyl value OH.V. was 55mg KOH/g.

Then, mixing the prepared polyester with 80kg of caprolactone and 40kg of butyrolactone, adding 1kg of polymerization initiator (TBD) and Desmodur N3300 kg of curing agent, stirring at high speed and mixing uniformly; ethyl acetate was added to dilute to 40% solids and the resulting solution was used as a polyester binder.

Comparative example 6

Example 2 of CN106905909 a:

20kg of neopentyl glycol, 35kg of ethylene glycol, 115kg of terephthalic acid, 40kg of isophthalic acid and 300g of tetrabutyl titanate were put into a reaction vessel. Displacing exhausted air with nitrogen, stirring and heating to 200-240 ℃ for reaction, taking the acid value of less than 30mg KOH/g as an end point, heating to 240-260 ℃ after the reaction is finished, carrying out polycondensation and stirring for 30min under the vacuum condition, introducing nitrogen to eliminate vacuum, extruding and discharging to obtain the polyester.

The obtained polyester: the intrinsic viscosity I.V. was 0.16, the glass transition temperature Tg was 35 ℃, the acid value A.V. was 6mg KOH/g and the hydroxyl value OH.V. was 50mg KOH/g.

Then, the polyester prepared by the method is mixed with 250kg of caprolactone, 150kg of butyrolactone and 20kg of lactide, then 2.2kg of polymerization initiator (THD) and 0.5kg of sodium methoxide are added, and 40kg of Desmodur N3300 is mixed and stirred evenly at high speed; ethyl acetate was added to dilute to 40% solids and the resulting solution was used as a polyester binder.

Application and performance evaluation of the adhesive:

preparing a composite membrane:

the examples and comparative examples of the present invention were used for adhesive lamination of an untreated PET film (MYLAR a-25 μm, duPont Teijin) with a polycarbonate film (PC film), a polymethyl methacrylate film (PMMA film), a PET sheet, and an aluminum foil substrate.

Respectively coating PET sheet (TUFTOP, toray), PC film (LEXAN, tekra), PMMA film (ACRYPLEN, mitsubishi Rayon) and aluminum foil (TOYAL) with adhesive, wherein the adhesive solid content is 10g/m ² And dried at 70 ℃ for 3 minutes. Then, an untreated PET film or a PET film whose adhesive face has been treated (by corona or other conventional treatment) is placed on the coated surface of the substrate so that the adhesive face is in contact with the adhesive coated surface, and then compounded using a flat press at a pressing pressure of 0.5MPa and a temperature of 50 ℃ for 10 minutes. Curing at 100 ℃ for 2h while pressing to obtain a composite layer.

1) And (3) testing the peel strength:

the composite layer was cut into 15mm × 200mm pieces, and a 180 ° peel test was performed at 25 ℃ and a test speed of 15mm/min using a mechanical property tester.

2) And (3) hydrolysis resistance test:

cutting the composite layer into 15mm × 200mm pieces, steaming in water bath at 100 deg.C for 24hr, and performing 180 ° peel test at 25 deg.C and 15mm/min using mechanical property tester.

Evaluation criteria:

3) Salt spray aging resistance test:

referring to the test method of ASTM G85-A5, the composite layer was cut into 100mm by 200mm pieces, placed in a testing machine, and the time at which the chalking, blistering or flaking phenomenon occurred was recorded.

4) And (3) accelerated aging test by an oxygen pressure method:

the composite layer was cut into 15mm x 200mm pieces with reference to the test method of ASTM D3632 and the time to retain 50% of the initial bond force was recorded at 70 c under an oxygen pressure of 0.1 MPa.

The results of the above performance tests are shown in table 1,

table 1: performance comparison results table:

as can be seen from the above table, the adhesive of the present invention has high adhesion strength to an untreated PET film and a base material of a different material, and is also excellent in aging resistance.

The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. The polyester adhesive is characterized by comprising 30-45% of polyester, 3-10% of a curing agent and 50-66% of an organic solvent by mass percent; wherein the polyester is polymerized by polyalcohol, dibasic acid and lactone, and the alkyd ratio of the polyalcohol to the dibasic acid is 1.1-2.0; the lactone is one or more of 3-hydroxybutyrolactone, 3-hydroxypentanolactone, 3-hydroxycaprolactone, 4-hydroxypentanolactone, 4-hydroxycaprolactone, 5-hydroxynonalactone or 6-hydroxyheptalactone; the intrinsic viscosity of the polyester is 0.3-0.5, the acid value is 1-5 mg KOH/g, the hydroxyl value is 10-20 mg KOH/g, and the glass transition temperature is-5-20 ℃;

the preparation method of the polyester comprises the following steps: and reacting the polyalcohol, the dibasic acid and the lactone at 200-240 ℃ under the action of a catalyst until the acid value is less than 20mg KOH/g, heating to 240-260 ℃ after the reaction is stopped, and carrying out polycondensation reaction to obtain the polyester.

2. The polyester adhesive of claim 1, wherein the polyol is one or more of ethylene glycol, propylene glycol, butylene glycol, neopentyl glycol, methylpentanediol, pentanediol, heptanediol, octanediol, nonanediol, decanediol, cyclohexanedimethanol, cyclohexanediol, pentaerythritol, glycerol, trimethylolpropane, trimethylolethane, or trimethylolmethane;

the dibasic acid is one or more of adipic acid, terephthalic acid, isophthalic acid and sebacic acid;

the organic solvent is one or a combination of more of ethyl acetate, toluene, xylene and butyl acetate.

3. The polyester adhesive according to claim 1, wherein the amount of the catalyst is 0.03-0.05% by mass of the total amount of all the charged monomers.

4. The polyester adhesive of claim 1, wherein the catalyst is one or more of zinc, manganese, magnesium, calcium, cobalt acetate, butyl titanate, isopropyl titanate, titanium amino triethoxide, dibutyltin oxide, antimony trioxide, antimony glycol, or p-toluenesulfonic acid in combination.

5. The polyester adhesive of claim 1, wherein the curing agent is an aliphatic polyisocyanate-based curing agent.

6. The polyester adhesive according to claim 1, wherein the polyester adhesive is used for bonding an untreated PET film to other substrates, and the other substrates comprise a PET sheet, a PC film, a PMMA film, or an aluminum foil.

7. A method for preparing the polyester adhesive according to any one of claims 1 to 6,

and mixing the polyester, the curing agent and the organic solvent, and uniformly stirring.