CN115785880A

CN115785880A - Polyurethane adhesive and preparation method and application thereof

Info

Publication number: CN115785880A
Application number: CN202211567063.6A
Authority: CN
Inventors: 石同; 杨磊; 付小亮; 何勇
Original assignee: Wanhua Chemical Group Co Ltd
Current assignee: Wanhua Chemical Group Co Ltd
Priority date: 2022-12-07
Filing date: 2022-12-07
Publication date: 2023-03-14

Abstract

The invention provides a polyurethane adhesive and a preparation method and application thereof. The polyurethane adhesive is prepared from 65-94 parts by weight of high-molecular polyol and 5-23 parts by weight of diisocyanate; the high-molecular polyol comprises polyester polyol; the preparation raw materials of the polyester polyol comprise dibasic acid and dihydric alcohol; the diols include combinations of straight chain aliphatic diols and cycloaliphatic diols. According to the invention, the raw materials for preparing the polyurethane adhesive are polyester polyol with a special structure, so that the polyurethane adhesive has excellent hydrolysis resistance, high adhesive strength, long opening time and low activation temperature.

Description

Polyurethane adhesive and preparation method and application thereof

Technical Field

The invention belongs to the technical field of preparation of high polymer materials, and particularly relates to a polyurethane adhesive and a preparation method and application thereof.

Background

The polyurethane adhesive consists of high-molecular polyol, a chain extender and diisocyanate, wherein the polyester polyol in the high-molecular polyol has better bonding strength due to the ester bond, but has poor hydrolysis resistance due to the ester bond, so that the application of the polyurethane adhesive in a humid environment or on water is limited.

In order to obtain better initial adhesion and final adhesion strength, the adhesive is generally made of raw materials with stronger crystallization rate, but the viscosity maintaining time is shorter due to the high crystallization rate, and a plurality of patents explore how to obtain hydrolysis-resistant thermoplastic polyurethane adhesive.

For example, CN110205077A discloses a hydrolysis-resistant solvent type polyurethane adhesive synthesized by using an organic solvent, methyl methacrylate, dicumyl peroxide, fluorine modified microcrystalline wax, poly (neopentyl glycol adipate) polyol, 1, 6-hexamethylene diisocyanate, a small molecular chain extender and a cross-linking agent, wherein the added microcrystalline wax has good surface lubrication performance, can improve the smoothness of leather and reduce the crease rate, has good hydrophobic performance, and can effectively improve the hydrolysis resistance of a finished product. However, the poly (neopentyl glycol adipate) polyol used in the adhesive has poor crystallinity, and further has poor adhesive strength.

CN114426805A discloses a preparation method of a hydrolysis-resistant polyurethane hot melt adhesive. The polyurethane hot melt adhesive with excellent hydrolysis resistance is prepared by optimizing the matrix formula and adding modified inorganic filler and the like. The inorganic filler is modified by grafting, and the liquefied MDI-100HL is grafted to the surface of the inorganic filler by using a silane coupling agent, so that the inorganic filler can be uniformly dispersed in a polyurethane matrix, the matrix is reinforced by the inorganic filler, and meanwhile, the carbodiimide group in the MDI-100HL can improve the water resistance of the polyurethane through reaction. However, there is still a risk of uneven mixing by adding the modified silica, and the adhesive strength thereof is yet to be further improved.

At present, thermoplastic polyurethane adhesives with hydrolysis resistance, high adhesive strength and long open time are rarely reported at home and abroad.

Therefore, it is an urgent technical problem in the art to develop a polyurethane adhesive that can combine excellent hydrolysis resistance, high adhesive strength, long bondability time, and low activation temperature.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a polyurethane adhesive and a preparation method and application thereof. The preparation raw materials of the polyurethane adhesive are polyester polyol with a special structure, so that the polyurethane adhesive has excellent hydrolysis resistance, high adhesive strength, long opening time and low activation temperature.

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

in a first aspect, the present invention provides a polyurethane adhesive, which is prepared from 65 to 94 parts by weight of a high molecular polyol and 5 to 23 parts by weight of a diisocyanate; the high molecular polyol comprises polyester polyol; the preparation raw materials of the polyester polyol comprise dibasic acid and dihydric alcohol; a combination of the dihydric alcohol straight chain aliphatic dihydric alcohol and the alicyclic dihydric alcohol.

In the invention, the raw material of the polyester polyol adopts the alicyclic diol with a specific structure, so that the hydrolysis resistance is brought, and simultaneously, the crystallinity of the adhesive is damaged to a certain degree, and the long opening time is brought; the straight-chain aliphatic dihydric alcohol and the alicyclic dihydric alcohol with specific structures are matched with each other, so that the polyurethane adhesive has excellent hydrolysis resistance, high adhesive strength and long opening time, and the activation temperature is low.

Preferably, the raw material for preparing the polyurethane adhesive includes 65 to 94 parts by weight of polymer polyol, for example, 66 parts, 68 parts, 70 parts, 72 parts, 74 parts, 76 parts, 78 parts, 80 parts, 82 parts, 84 parts, 86 parts, 88 parts, 90 parts, 92 parts, etc.

Preferably, the raw materials for preparing the polyurethane adhesive include 5 to 23 parts of diisocyanate, for example, 6 parts, 8 parts, 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, 22 parts, etc. by weight.

Preferably, the dibasic acid comprises a C4 to C12 dibasic acid, and may be, for example, a C4, C5, C6, C7, C8, C9, C10, C11 dibasic acid.

In the invention, the polyester polyol prepared from the long-carbon-chain dibasic acid and the dihydric alcohol can further improve the comprehensive performance of the polyurethane adhesive.

Preferably, the dibasic acid comprises at least one of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid or sebacic acid.

The mass ratio of the dibasic acid to the glycol is preferably 1 (0.8 to 1.6), wherein specific values in (0.8 to 1.6) may be, for example, 0.82, 0.84, 0.86, 0.88, 0.9, 0.92, 0.94, 0.96, 0.98, 1, 1.1, 1.2, 1.3, 1.4, 1.5, and the like.

Preferably, the linear aliphatic diol includes C4 to C12 linear aliphatic diols, which may be, for example, C5, C6, C7, C8, C9, C10, C11 linear aliphatic diols, and the like.

Preferably, the linear aliphatic diol comprises at least one of butanediol, hexanediol, decanediol or dodecanediol.

Preferably, the cycloaliphatic diol comprises a C4 to C20 cycloaliphatic diol, which may be, for example, a C5, C6, C7, C8, C9, C10, C11, C12, C13, C14, C15, C16, C17, C18, C19 cycloaliphatic diol, or the like.

Preferably, the cycloaliphatic diol comprises at least one of cyclopentane-1, 3-diol, 1, 2-cyclohexanediol, 1, 4-cyclohexanediol, 1, 5-cyclooctanediol, or 1, 4-cyclohexanedimethanol.

The mass ratio of the linear aliphatic diol to the alicyclic diol is preferably 1 (0.5 to 1), and specific values of (0.5 to 1) may be, for example, 0.52, 0.54, 0.56, 0.58, 0.6, 0.62, 0.64, 0.66, 0.68, 0.7, 0.72, 0.74, 0.76, 0.78, 0.8, 0.82, 0.84, 0.86, 0.88, 0.9, 0.92, 0.94, 0.96, 0.98, or the like.

Preferably, the acid value of the polyester polyol is less than 1mgKOH/g, and may be, for example, 0.2mgKOH/g, 0.4mgKOH/g, 0.6mgKOH/g, 0.8mgKOH/g, or the like.

Preferably, the polyester polyol has a hydroxyl value of 28 to 62mgKOH/g, and may be, for example, 30mgKOH/g, 35mgKOH/g, 40mgKOH/g, 45mgKOH/g, 50mgKOH/g, 55mgKOH/g, 60mgKOH/g, or the like.

The number average molecular weight of the polymer polyol is preferably 1800 to 4000g/mol, and may be 1900g/mol, 2000g/mol, 2100g/mol, 2200g/mol, 2400g/mol, 2600g/mol, 2800g/mol, 3000g/mol, 3200g/mol, 3400g/mol, 3600g/mol, 3800g/mol, etc., and more preferably 2500 to 3500g/mol.

In the present invention, the preparation method of the polyester polyol comprises: and reacting the dibasic acid with the dihydric alcohol to obtain the polyester polyol.

Preferably, the reacting comprises reacting through a first stage, a second stage, and a third stage.

Preferably, the reaction temperature in the first stage is 130 to 140 ℃, for example, 132 ℃, 134 ℃, 136 ℃, 138 ℃ and the like; the reaction time is 1 to 2 hours, and for example, 1 hour, 1.5 hours, 2 hours and the like can be used.

Preferably, the reaction temperature of the second stage is 160-170 ℃, for example 162 ℃, 164 ℃, 166 ℃, 168 ℃ and the like; the reaction time is 1 to 2 hours, and may be, for example, 1 hour, 1.5 hours, 2 hours, or the like.

Preferably, the reaction temperature of the third stage is 200 to 210 ℃, and may be, for example, 202 ℃, 204 ℃, 206 ℃, 208 ℃ or the like; the reaction time is 3 to 4 hours, and may be, for example, 3 hours, 3.5 hours, 4 hours, or the like.

Preferably, the reaction is carried out under vacuum conditions.

Preferably, the polymer polyol further includes at least one of polycaprolactone polyol, polyether polyol, or polycarbonate polyol.

Preferably, the diisocyanate comprises at least one of diphenylmethane diisocyanate, hexamethylene diisocyanate, 4-dicyclohexylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, m-xylylene diisocyanate, 1, 5-naphthalene diisocyanate, preferably at least one of hexamethylene diisocyanate, diphenylmethane diisocyanate or isophorone diisocyanate.

Preferably, the polyurethane adhesive also comprises 0 to 18 parts by weight of chain extender, such as 0.5 part, 1 part, 2 parts, 4 parts, 6 parts, 8 parts, 10 parts, 12 parts, 14 parts, 16 parts and the like.

Preferably, the chain extender comprises at least one of 1, 2-ethanediol, 1, 4-butanediol, neopentyl glycol, 1, 6-hexanediol, diethylene glycol or cis-1, 2-cyclohexanedimethanol, and more preferably at least one of neopentyl glycol, 1, 4-butanediol, 1, 6-hexanediol or cis-1, 2-cyclohexanedimethanol.

As a preferable technical scheme of the invention, the preparation raw materials of the polyurethane adhesive comprise 70-92 parts of high polymer polyol, 12-22 parts of diisocyanate and 0.1-10 parts of chain extender by weight.

In a second aspect, the present invention provides a method for preparing the polyurethane adhesive according to the first aspect, the method comprising:

and (3) mixing high-molecular polyol with diisocyanate, and reacting to obtain the polyurethane adhesive.

Preferably, the mixed raw material further comprises a chain extender.

Preferably, the reaction is carried out in a twin screw extruder.

Preferably, the temperature of the twin-screw extruder is 150 to 200 ℃, and may be, for example, 160 ℃, 170 ℃, 180 ℃, 190 ℃, or the like.

In the invention, the double-screw extruder is divided into a first zone, a second zone, a third zone, a fourth zone, a fifth zone, a sixth zone, a seventh zone, an eighth zone, a ninth zone and a tenth zone. The temperatures of the first zone and the second zone are respectively and independently 150-170 ℃; the temperatures of the three, four and five zones are respectively and independently 160-180 ℃; the temperature of the six zone, the seven zone and the eight zone is 170-190 ℃ respectively and independently; the temperature of the nine area and the ten area is respectively and independently 160-180 ℃; the temperature of the die head of the double-screw extruder is 160-180 ℃.

Preferably, the reaction further comprises a granulation step.

In the present invention, the granulation is carried out in water.

In the invention, when the polyurethane adhesive is used, the adhesive needs to be dissolved in a solvent to form a solution, and an auxiliary agent can be added according to requirements when the adhesive is dissolved.

Preferably, the solvent comprises at least one of butanone, acetone, toluene, ethyl acetate, methyl acetate, dimethyl carbonate, or tetrahydrofuran.

Preferably, the auxiliary agent comprises at least one of a leveling agent, a thickening agent, a curing agent, a UV auxiliary agent or a hydrolysis resistance agent.

In a third aspect, the present invention provides a use of the polyurethane adhesive according to the first aspect for bonding PVC, fabric, leather or foam; the adhesive is preferably used for bonding substrates in a wet environment, and is more preferably used for bonding PVC, fabrics, leather and foam in a wet environment for a long working time.

The numerical ranges set forth herein include not only the points recited above, but also any points between the numerical ranges not recited above, and are not exhaustive of the particular points included in the ranges for reasons of brevity and clarity.

Compared with the prior art, the invention has the beneficial effects that:

according to the polyurethane adhesive provided by the invention, the preparation raw materials of the polyester polyol select the dihydric alcohol and the dibasic acid with a specific structure, so that the polyurethane adhesive has excellent hydrolysis resistance and bonding performance, and is long in opening time and low in activation temperature; the peel strength can reach more than 2.1N/mm at 25 ℃ and even can cause substrate damage, the hydrolytic strength retention rate is more than or equal to 88 percent after the treatment for 7 days under the condition of 70 ℃ and 95 percent RH, the sticking time is more than or equal to 120min, and the comprehensive performance is excellent.

Detailed Description

The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitation of the present invention.

The raw materials and instruments used and their uses (all chemically pure) were as follows:

adipic acid (Huafeng)

Sebacic acid (Mecline)

Hexanediol (Mecline)

Decanediol (Mecline)

Dodecanediol (Meclin)

Cyclopentane-1, 3-diol (Michalin)

1, 4-cyclohexanediol (Meclin)

1, 5-cyclooctadiene alcohol (Meclin)

1, 4-cyclohexanedimethanol (Meclin)

1, 2-cyclohexanediol (Meclin)

Neopentyl glycol (Mecline)

Butanediol (Wanhua chemical)

Hexamethylene diisocyanate (Wanhua chemical)

Diphenylmethane diisocyanate (Wanhua chemical)

Isophorone diisocyanate (Wanhua chemical)

Finished positive glass burette: testing the acid value of the polyester polyol;

hydroxyl number analyzer (Thermo Fisher Antarisll): measuring the hydroxyl value of the polyester polyol;

an extruder: nanjing Ruiya extruder manufactures the company RXT, LLC (diameter: 42mm, aspect ratio: 46).

Preparation example 1

A polyester polyol with a special structure is prepared from raw materials comprising dibasic acid and dihydric alcohol in a mass ratio of 1; the dibasic acid comprises sebacic acid; the dihydric alcohol comprises dodecanediol and 1, 5-cyclooctadiene alcohol in a mass ratio of 1.

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

adding sebacic acid, dodecanediol and 1, 5-cyclooctadiene into a reaction kettle with a fractionating tower and a distillation receiver, sequentially reacting for 2h at 140 ℃, reacting for 2h at 170 ℃, reacting for 4.0h at 210 ℃, simultaneously starting vacuum, removing reaction product water and excessive alcohol monomers, stopping the reaction when the acid value is less than 1mg KOH/g and the hydroxyl value reaches 38mg KOH/g, and then the corresponding number average molecular weight is 3000g/mol.

Preparation example 2

The polyester polyol with a special structure is prepared from raw materials comprising dibasic acid and dihydric alcohol in a mass ratio of 1; the dibasic acid comprises sebacic acid; the dihydric alcohol comprises 1, 4-cyclohexanedimethanol and decamethylene with the mass ratio of 1.

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

adding sebacic acid, decanediol and 1, 4-cyclohexanedimethanol into a reaction kettle with a fractionating tower and a distillation receiver, reacting for 1h at 140 ℃, reacting for 1.5h at 170 ℃, reacting for 4.0h at 210 ℃, simultaneously starting vacuum, removing reaction product water and redundant alcohol monomers, stopping reaction when the acid value is less than 1mg KOH/g and the hydroxyl value reaches 38mg KOH/g, and then the corresponding number average molecular weight is 3000g/mol.

Preparation example 3

The polyester polyol with a special structure is prepared from raw materials comprising dibasic acid and dihydric alcohol in a mass ratio of 1; the dibasic acid comprises sebacic acid; the dihydric alcohol comprises dodecanediol and 1, 2-cyclohexanediol in a mass ratio of 1.574.

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

adding sebacic acid, dodecanediol and 1, 2-cyclohexanediol into a reaction kettle with a fractionating tower and a distillation receiver, sequentially reacting for 1.5h at 140 ℃, 2h at 170 ℃ and 3.5h at 210 ℃, simultaneously starting vacuum, removing reaction product water and redundant alcohol monomers, stopping reaction when the acid value is less than 1mg KOH/g and the hydroxyl value reaches 38mg KOH/g, and then the corresponding number average molecular weight is 3000g/mol.

Preparation example 4

The polyester polyol with a special structure is prepared from raw materials comprising dibasic acid and dihydric alcohol in a mass ratio of 1; the dibasic acid comprises sebacic acid; the dihydric alcohol comprises dodecanediol and 1, 5-cyclooctadiene in a mass ratio of 1.

The polyester polyol was prepared in the same manner as in preparation example 1.

Preparation example 5

A polyester polyol with a special structure is prepared from raw materials comprising dibasic acid and dihydric alcohol in a mass ratio of 1; the dibasic acid comprises adipic acid; the dihydric alcohol comprises hexanediol and 1, 4-cyclohexanediol in a mass ratio of 1.

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

adding adipic acid, hexanediol and 1, 4-cyclohexanediol into a reaction kettle with a fractionating tower and a distillation receiver, reacting for 1h at 140 ℃, reacting for 2h at 170 ℃, reacting for 4.0h at 210 ℃, simultaneously starting vacuum, removing reaction product water and excessive alcohol monomer, stopping reaction when the acid value is less than 1mg KOH/g and the hydroxyl value reaches 38mg KOH/g, and then the corresponding number average molecular weight is 3000g/mol.

Preparation example 6

A polyester polyol with a special structure is different from the polyester polyol in the preparation example 1 only in that the total mass of the dodecanediol and the 1, 5-cyclooctadiene is unchanged, the mass ratio is 1:0.25, and other raw materials, the using amount and the preparation method are the same as those in the preparation example 1.

Preparation example 7

A polyester polyol with a special structure is different from the polyester polyol in the preparation example 1 only in that the total mass of dodecanediol and 1, 5-cyclooctanediol is unchanged, the mass ratio is 1.2, and other raw materials, the using amount and the preparation method are the same as those in the preparation example 1.

Preparation example 8

A polyester polyol having a specific structure, which is different from preparation example 1 only in that dodecanediol is replaced with 1, 6-hexanediol; the 1, 5-cyclooctadiene alcohol was replaced with 1, 4-cyclohexanedimethanol, and the other raw materials, amounts and preparation methods were the same as in preparation example 1.

Comparative preparation example 1

A polyester polyol is prepared from raw materials including 1; the dibasic acid comprises sebacic acid; the dihydric alcohol comprises butanediol and hexanediol with the mass ratio of 1.

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

adding sebacic acid, butanediol and hexanediol into a reaction kettle with a fractionating tower and a distillation receiver, reacting for 1h at 130 ℃, reacting for 1.5h at 160 ℃ and reacting for 3h at 200 ℃, simultaneously, starting vacuum, removing reaction product water and redundant alcohol monomers, stopping reaction when the acid value is less than 1mg KOH/g and the hydroxyl value reaches 38mg KOH/g, and then the corresponding number average molecular weight is 3000g/mol.

Comparative preparation example 2

The polyester polyol is prepared from the following raw materials, namely 1; the dibasic acid comprises sebacic acid; the dihydric alcohol comprises cyclopentane-1, 3-diol and 1, 2-cyclohexanediol in a mass ratio of 1.137.

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

adding sebacic acid, cyclopentane-1, 3-diol and 1, 2-cyclohexanediol into a reaction kettle with a fractionating tower and a distillation receiver, reacting for 1h at 140 ℃, 1.5h at 170 ℃ and 4h at 210 ℃, simultaneously starting vacuum, removing reaction product water and excessive alcohol monomer, stopping reaction when the acid value is less than 1mg KOH/g and the hydroxyl value reaches 38mg KOH/g, and the corresponding number average molecular weight is 3000g/mol.

Comparative preparation example 3

This comparative example provides a polyester polyol which is different from preparation example 1 only in that the 1, 5-cyclooctadiene alcohol is replaced with dodecanediol, and other raw materials, amounts, and preparation methods are the same as those of preparation example 1.

Comparative preparation example 4

This comparative example provides a polyester polyol which differs from preparation example 1 only in that dodecanediol is replaced with 1, 5-cyclooctanediol, and other raw materials, amounts, and preparation methods are the same as those of preparation example 1.

Comparative preparation example 5

This comparative example provides a polyester polyol which is different from preparation example 1 only in that dodecanediol is replaced with 2-methyl-2, 5-decanediol, and other raw materials, amounts and preparation methods are the same as those of preparation example 1.

Example 1

This example provides a polyurethane adhesive prepared from 81 parts by weight of a polyester polyol (preparation example 1), 15 parts of 4, 4-diphenylmethane diisocyanate, and 4 parts of cis-1, 2-cyclohexanedimethanol.

The embodiment provides a preparation method of a polyurethane adhesive, which specifically comprises the following steps:

adding polyester polyol, 4-diphenylmethane diisocyanate and cis-1, 2-cyclohexanedimethanol into an extruder, uniformly mixing, and performing reaction extrusion by using a double screw; extruder temperature: and the first zone, the second zone, the third zone, the fourth zone and the fifth zone are all 160 ℃, the sixth zone, the seventh zone and the eighth zone are all 170 ℃, the ninth zone and the tenth zone are all 160 ℃, the temperature of a die head is 160 ℃, and then the polyurethane adhesive is obtained by underwater grain cutting.

Example 2

This example provides a polyurethane adhesive prepared from 84 parts by weight of a polyester polyol (preparation example 1), 12 parts by weight of hexamethylene diisocyanate, and 4 parts by weight of 1, 4-butanediol.

adding polyester polyol, hexamethylene diisocyanate and 1, 4-butanediol into an extruder, uniformly mixing, and performing double-screw reaction and extrusion; extruder temperature: the first zone and the second zone are both 160 ℃, the third zone, the fourth zone and the fifth zone are all 170 ℃, the sixth zone, the seventh zone and the eighth zone are all 180 ℃, the ninth zone and the tenth zone are all 170 ℃, the die head temperature is 170 ℃, and then the polyurethane adhesive is obtained by underwater grain cutting.

Example 3

This example provides a polyurethane adhesive prepared from 83 parts by weight of a polyester polyol (preparation example 2), 13.5 parts of isophorone diisocyanate, and 3.5 parts of neopentyl glycol.

adding polyester polyol, isophorone diisocyanate and neopentyl glycol into an extruder, uniformly mixing, and extruding by a double-screw reaction; extruder temperature: the first zone and the second zone are 170 ℃, the third zone, the fourth zone and the fifth zone are 180 ℃, the sixth zone, the seventh zone and the eighth zone are 190 ℃, the ninth zone and the tenth zone are 180 ℃, the temperature of a die head is 180 ℃, and then the polyurethane adhesive is obtained by underwater grain cutting.

Example 4

This example provides a polyurethane adhesive prepared from 81 parts by weight of a polyester polyol (preparation example 2), 13 parts by weight of hexamethylene diisocyanate, and 6 parts by weight of 1, 6-hexanediol.

adding polyester polyol, hexamethylene diisocyanate and 1, 6-hexanediol into an extruder, uniformly mixing, and extruding by a double-screw reaction; extruder temperature: the first zone and the second zone are 170 ℃, the third zone, the fourth zone and the fifth zone are 180 ℃, the sixth zone, the seventh zone and the eighth zone are 190 ℃, the ninth zone and the tenth zone are 180 ℃, the temperature of a die head is 180 ℃, and then the polyurethane adhesive is obtained by underwater grain cutting.

Example 5

This example provides a polyurethane adhesive prepared from 90 parts by weight of a polyester polyol (preparation example 3), 9 parts by weight of isophorone diisocyanate, and 1 part by weight of 1, 4-butanediol.

adding polyester polyol, isophorone diisocyanate and 1, 4-butanediol into an extruder, uniformly mixing, and performing double-screw reaction and extrusion; extruder temperature: the first zone and the second zone are both 160 ℃, the third zone, the fourth zone and the fifth zone are all 170 ℃, the sixth zone, the seventh zone and the eighth zone are all 180 ℃, the ninth zone and the tenth zone are all 170 ℃, the die head temperature is 170 ℃, and then the polyurethane adhesive is obtained by underwater grain cutting.

Example 6

This example provides a polyurethane adhesive which differs from example 1 only in that the polyester polyol provided in preparation example 4 is selected and the other raw materials, amounts and preparation methods are the same as those of example 1.

Example 7

This example provides a polyurethane adhesive prepared from 83 parts by weight of a polyester polyol (preparation example 5), 13 parts by weight of isophorone diisocyanate, and 4 parts by weight of 1, 6-hexanediol.

adding polyester polyol, isophorone diisocyanate and 1, 6-hexanediol into an extruder, uniformly mixing, and performing double-screw reaction and extrusion; extruder temperature: the first zone and the second zone are both 150 ℃, the third zone, the fourth zone and the fifth zone are all 160 ℃, the sixth zone, the seventh zone and the eighth zone are all 170 ℃, the ninth zone and the tenth zone are all 160 ℃, the die head temperature is 160 ℃, and then the polyurethane adhesive is obtained by underwater grain cutting.

Examples 8 to 10

The polyurethane adhesives provided in examples 8 to 10 differ from example 1 only in that the polyester polyols provided in preparation examples 6 to 8 were selected as the polyester polyols, respectively, and the other raw materials, amounts and preparation methods were the same as those of example 1.

Comparative example 1

This comparative example provides a polyurethane adhesive prepared from raw materials including, by weight, 85 parts of PCL-3000, 11.5 parts of hexamethylene diisocyanate, and 3.5 parts of 1, 4-butanediol.

The comparative example provides a method of preparing a polyurethane adhesive, specifically comprising the steps of:

adding PCL-3000, hexamethylene diisocyanate and 1, 4-butanediol into an extruder, uniformly mixing, and extruding by a double-screw extruder, wherein the temperature of the extruder is as follows: and (3) cutting the polyurethane adhesive under water to obtain the polyurethane adhesive, wherein the first zone and the second zone are both 160 ℃, the third zone, the fourth zone and the fifth zone are all 170 ℃, the sixth zone, the seventh zone and the eighth zone are all 180 ℃, the ninth zone and the tenth zone are all 170 ℃, and the temperature of a die head is 170 ℃.

Comparative example 2

This comparative example provides a polyurethane adhesive prepared from raw materials including, by weight, 84 parts of polyester polyol (comparative preparation example 1), 12 parts of hexamethylene diisocyanate, and 4 parts of 1, 4-butanediol.

The comparative example provides a preparation method of a polyurethane adhesive, which specifically comprises the following steps:

adding polyester polyol, hexamethylene diisocyanate and 1, 4-butanediol into an extruder, uniformly mixing, and extruding by a double-screw extruder, wherein the temperature of the extruder is as follows: the first zone and the second zone are both 160 ℃, the third zone, the fourth zone and the fifth zone are all 170 ℃, the sixth zone, the seventh zone and the eighth zone are all 180 ℃, the ninth zone and the tenth zone are all 170 ℃, the die head temperature is 170 ℃, and then the polyurethane adhesive is obtained by underwater grain cutting.

Comparative example 3

This comparative example provides a polyurethane adhesive prepared from 84 parts by weight of a polyester polyol (comparative preparation example 2), 12 parts by weight of hexamethylene diisocyanate, and 4 parts by weight of 1, 4-butanediol.

adding polyester polyol, hexamethylene diisocyanate and 1, 4-butanediol into an extruder, uniformly mixing, extruding by a double-screw reaction, wherein the temperature of the extruder is as follows: the first zone and the second zone are both 160 ℃, the third zone, the fourth zone and the fifth zone are all 170 ℃, the sixth zone, the seventh zone and the eighth zone are all 180 ℃, the ninth zone and the tenth zone are all 170 ℃, the die head temperature is 170 ℃, and then the polyurethane adhesive is obtained by underwater grain cutting.

Comparative examples 4 to 6

Comparative examples 4 to 6 provide polyurethane adhesives which are different from example 1 only in that the polyester polyols are the polyester polyols provided in comparative preparation examples 3 to 5, respectively, and other raw materials, amounts and preparation methods are the same as those of example 1.

Performance test

Hydrolysis resistance: the test base material is PVC, the pasted sample strip is placed in a constant temperature and humidity box (70 ℃/95% humidity), after being placed for 14 days, the peel strength is compared with that of a blank sample strip, and the strength retention rate after hydrolysis is tested; the instrument comprises: humid heat ageing oven (Memmert CTCZ 56);

tack free time: coating the glue solution on a base material, and testing whether the base material has viscosity at intervals under the room temperature condition, wherein the viscosity maintaining time is the viscidity time;

peel strength: the base material is PE, a tensile machine (SHIMADZU AGX-X); testing was performed according to GB/T528-2009.

Here, "-" indicates that the substrate was damaged due to high peel strength, and a specific value could not be measured, indicating excellent adhesion.

The specific test results are shown in table 1:

TABLE 1

As can be seen from the above table, the preparation raw materials of the polyurethane adhesive provided by the invention, namely the diol and the dibasic acid with specific structures are selected, so that the polyurethane adhesive has excellent hydrolysis resistance and bonding performance, and has the advantages of long opening time and low activation temperature; as is clear from examples 1 to 7, the above polyurethane adhesive can achieve a peel strength of 3.2N/mm or more at 25 ℃ and even cause substrate breakage, and has a strength retention of 88 to 99% after hydrolysis for 14 days of treatment at 70 ℃ and 95% RH, a bondable time of 260 to 330min, and excellent overall properties.

It is understood from examples 1 and 8 to 9 that the mass ratio of the linear aliphatic diol to the alicyclic diol is not within a specific range, and the tack time is shortened or the peel strength is lowered.

As is clear from examples 1 and 10, 1, 6-hexanediol and 1, 4-cyclohexanedimethanol, which are selected as the linear aliphatic diol and the alicyclic diol, have a shortened tack time and a reduced peel strength.

As can be seen from example 1 and comparative example 1, the polyurethane adhesive has reduced hydrolysis resistance and shorter bondability time by replacing the polyester polyol having a specific structure in the present application with a conventional polycaprolactone polyol.

As can be seen from example 1 and comparative examples 2 and 3, when two different straight-chain aliphatic diols or two different alicyclic diols are used as the diols, the polyurethane adhesive has reduced hydrolysis resistance, reduced bondability time, or reduced peel strength.

As can be seen from example 1 and comparative examples 4 to 6, the diol does not contain an alicyclic diol or a linear aliphatic diol, or the aliphatic diol has a pendant group in the main chain, and the urethane adhesive has a short adhesive time, a low peel strength, and a high activation temperature.

In summary, the polyurethane adhesive provided by the invention uses the long linear chain dihydric alcohol and the long linear chain dibasic acid with specific structures, so that the polyurethane has excellent water resistance and excellent adhesive property, and has long open time and low activation temperature. Is especially suitable for bonding PVC, fabric, leather and foam for long working time in humid environment

The above-mentioned embodiments, objects, technical solutions and advantages of the present invention are further described in detail, it should be understood that the above-mentioned embodiments are only examples of the present invention, and should not be construed as limiting the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The polyurethane adhesive is characterized in that the preparation raw materials of the polyurethane adhesive comprise 65-94 parts of high-molecular polyol and 5-23 parts of diisocyanate in parts by weight;

the high molecular polyol comprises polyester polyol;

the preparation raw materials of the polyester polyol comprise dibasic acid and dihydric alcohol;

the diols include combinations of straight chain aliphatic diols and cycloaliphatic diols.

2. The polyurethane adhesive of claim 1, wherein the dibasic acid comprises a C4 to C12 dibasic acid;

preferably, the dibasic acid comprises at least one of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid or sebacic acid;

preferably, the mass ratio of the dibasic acid to the dihydric alcohol is 1 (0.8-1.6).

3. The polyurethane adhesive of claim 1 or 2, wherein the linear aliphatic diol comprises a C4 to C12 linear aliphatic diol;

preferably, the linear aliphatic diol comprises at least one of butanediol, hexanediol, decanediol, or dodecanediol;

preferably, the cycloaliphatic diol comprises a C4 to C20 cycloaliphatic diol;

preferably, the cycloaliphatic diol comprises at least one of cyclopentane-1, 3-diol, 1, 2-cyclohexanediol, 1, 4-cyclohexanediol, 1, 5-cyclooctanediol, or 1, 4-cyclohexanedimethanol;

preferably, the mass ratio of the linear aliphatic diol to the cycloaliphatic diol is 1 (0.5-1).

4. A polyurethane adhesive as claimed in any one of claims 1 to 3, wherein the polyester polyol has an acid value of less than 1mgKOH/g;

preferably, the hydroxyl value of the polyester polyol is 28 to 62mgKOH/g;

preferably, the number average molecular weight of the polymer polyol is 1800 to 4000g/mol;

5. The polyurethane adhesive of any one of claims 1 to 4, wherein the diisocyanate comprises at least one of diphenylmethane diisocyanate, hexamethylene diisocyanate, 4-dicyclohexylmethane diisocyanate, toluene diisocyanate, isophorone diisocyanate, m-xylylene diisocyanate, 1, 5-naphthalene diisocyanate, preferably at least one of hexamethylene diisocyanate, diphenylmethane diisocyanate, or isophorone diisocyanate;

preferably, the polyurethane adhesive also comprises 0-18 parts by weight of chain extender;

preferably, the chain extender comprises at least one of 1, 2-ethylene glycol, 1, 4-butanediol, neopentyl glycol, 1, 6-hexanediol, diethylene glycol, or cis-1, 2-cyclohexanedimethanol, and more preferably at least one of neopentyl glycol, 1, 4-butanediol, 1, 6-hexanediol, or cis-1, 2-cyclohexanedimethanol.

6. The polyurethane adhesive according to any one of claims 1 to 5, wherein the polyurethane adhesive is prepared from 70 to 92 parts by weight of a high molecular polyol, 12 to 22 parts by weight of a diisocyanate, and 0.1 to 10 parts by weight of a chain extender.

7. A method of preparing the polyurethane adhesive of any one of claims 1-6, wherein the method comprises:

and mixing high-molecular polyol with diisocyanate, and reacting to obtain the polyurethane adhesive.

8. The method of claim 7, wherein the mixed feedstock further comprises a chain extender;

preferably, the reaction is carried out in a twin screw extruder.

9. The method for preparing the polypropylene composition according to claim 8, wherein the temperature of the twin-screw extruder is 150 to 200 ℃;

preferably, the reaction also comprises a granulation step.

10. Use of a polyurethane adhesive according to any one of claims 1 to 6 for bonding PVC, textiles, leather or foam.