CN110684487B

CN110684487B - Two-component aqueous adhesive, method for bonding first surface to second surface based on same and product thereof

Info

Publication number: CN110684487B
Application number: CN201810735426.XA
Authority: CN
Inventors: 陈莉莉
Original assignee: Shanghai Bilin Chemical Technology Co ltd
Current assignee: Shanghai Bilin Chemical Technology Co ltd
Priority date: 2018-07-06
Filing date: 2018-07-06
Publication date: 2022-01-14
Anticipated expiration: 2038-07-06
Also published as: CN110684487A

Abstract

The present invention relates to a two-component aqueous adhesive, a method of bonding a first surface to a second surface based thereon, and articles thereof. The two-component aqueous adhesive of the present invention comprises a first component comprising at least one compound containing two or more hydrazide groups; at least one acidic substance is added into the second component, and the pH value of the second component is not more than 4; at least one of the first component and the second component further contains a polyacrylate copolymer emulsion obtained by copolymerizing monomers having an aldehyde or ketone group. The two-component water-based adhesive has good initial adhesion, final adhesion and temperature resistance, and can be used for contact bonding between surfaces of various substrates.

Description

Two-component aqueous adhesive, method for bonding first surface to second surface based on same and product thereof

Technical Field

The invention belongs to the field of bi-component adhesives, and particularly relates to a bi-component water-based adhesive and an adhesion method.

Background

The contact adhesive, also called contact adhesive, is characterized by that after the adhesive is coated, it can be "contacted" within a certain time to produce adhesive action, i.e. the adhesive can be coated on the surfaces of two adherends, and can be contacted with each other to produce adhesion, and the adhered surface can be dried to form film-like adhesive layer. Contact adhesives generally need to have the following characteristics: (1) the adhesive has high bonding force within a short time (1-5 minutes), namely, the adhesive can be self-adhered, can form a semisolid film which can sufficiently combine base materials together, and meets the operation of cutting and other procedures before the adhesive is completely dried; (2) has higher final viscosity and plays a permanent role; (3) high temperature resistance, and no glue failure in the transportation and use process.

The solvent-based contact adhesive is an adhesive with quick-drying property, when the contact adhesive is applied to the surface of a base material to be bonded, after a short period of solvent volatilization, the adhesive-coated surface of the base material to be bonded is contacted and bonded, and the base materials to be bonded can be bonded together under the action of pressure. The Brath adopts neoprene as a base material in 1975, p-tert-butylphenol formaldehyde resin prepared by an alkali catalyst is used as tackifying resin, and a small amount of zinc oxide is added to prepare the contact adhesive with high peel strength. However, the main disadvantage of the solvent-based contact adhesive is that the addition amount of volatile organic solvent is high, and in most cases, the volatile organic solvent can account for more than 60% of the weight of the adhesive, and a large amount of solvent volatilizes in the use process to cause environmental pollution, and in addition, the solvents generally have flammability to bring certain potential safety hazard. Accordingly, it is a goal of the adhesive industry to develop alternative contact glues that dry quickly and have physical properties equivalent to solvent-based contact glues, but where the amount of organic solvents is significantly reduced or eliminated altogether.

The water-based adhesive is an environment-friendly adhesive, uses water as a carrier, and has no environmental pollution in the drying process. However, the water-based adhesives volatilize very slowly during use due to the high boiling point of water. This characteristic causes the initial viscosity of the aqueous contact adhesive to be extremely poor and cannot meet the production requirements. Patent document 1 discloses a high-efficiency solvent-free contact adhesive comprising a polymer aqueous emulsion, thermoplastic hollow microspheres and the like, wherein the drying time is 1 hour. Therefore, the development of an aqueous contact adhesive with high initial viscosity is one of the problems to be solved in the art.

In order to solve the technical problem, patent document 2 discloses a one-pack, storage-stable, water-based contact adhesive composition containing an internal coagulant, which comprises polychloroprene in an aqueous dispersion, a resin component selected from the group consisting of ethylene-vinyl acetate copolymers, polyvinyl acetate homopolymers, polyvinyl acetate copolymers, acrylic copolymers, polyvinyl acetate-acrylic copolymers and mixtures thereof, and the internal coagulant contains a hygroscopic salt. The adhesive composition of this document can shorten the drying time, but the heat resistance is yet to be enhanced.

Patent document 3 discloses an aqueous polychloroprene contact adhesive comprising polychloroprene, at least one alkyd-type self-crosslinking agent and at least one filler, which is used as a contact adhesive to assemble two materials, the adhesive composition of this document has increased cohesive strength and storage stability, but the production cost of the aqueous polychloroprene dispersion and the aqueous alkyd-type self-crosslinking agent is high and the crosslinking speed of the alkyd-type self-crosslinking agent is slow, and therefore the adhesive requires a long aging time.

There have also been attempts by developers to develop two-part (two-part) water-dispersed high solids adhesive systems that demonstrate the necessary tack properties of two-part waterborne neoprene (see DuPont Dow Elastomer, AquaStik)^TM). Patent document 4 also discloses an aging-resistant and hardening-resistant two-component water-based spray adhesive and a preparation method thereof, wherein the spray adhesive comprises a component a and a component B, the component a comprises water-based chloroprene rubber emulsion, acrylic emulsion and the like, the component B comprises rosin resin, isocyanate and the like, after the spray adhesive is used, the adhesive layer is not hardened after the bonding position of the adhesive is cured, and the bonding position is not hard-edged, so that the problem of hard-edged after the traditional water-based adhesive is cured can be solved. But the production cost is high, complex encapsulation is needed, the using open time of the second component is short, and the isocyanate can be hydrolyzed and loses efficacy after contacting with water, so the stability and the market popularization are in a disadvantage.

In order to reduce the production cost of two-component aqueous neoprene, other types of aqueous dispersions or aqueous adhesives have also been reported in the literature. For example, patent document 5 discloses an aqueous dispersion containing a carbonyl group-containing copolymer and a hydrazine derivative, and a certain amount of heavy metal ions is added thereto to accelerate crosslinking, and the dispersion can be used as a raw material for adhesives, but is low in initial tackiness, poor in quick drying ability, and is not suitable as a contact adhesive.

Patent document 1: US5264467A

Patent document 2: CN1367810A

Patent document 3: WO2016132039A1

Patent document 4: CN107189720A

Patent document 5: US4250070A

Disclosure of Invention

Problems to be solved by the invention

In order to solve the defects and shortcomings of the prior art, the invention provides the double-component water-based adhesive with good initial adhesion, final adhesion and temperature resistance.

The invention also provides a method for bonding a first surface to a second surface based on the two-component aqueous adhesive.

In addition, the invention also provides an adhesive product.

Means for solving the problems

The invention provides a two-component aqueous adhesive comprising a first component and a second component; said first component comprising at least one compound containing two or more hydrazide groups; at least one acidic substance is added into the second component, and the pH value of the second component is not more than 4; at least one of the first component and the second component also contains polyacrylate copolymer emulsion prepared by the copolymerization of monomers with aldehyde or ketone groups, namely the first component and/or the second component also contains polyacrylate copolymer emulsion prepared by the copolymerization of monomers with aldehyde or ketone groups.

Preferably, the monomer having an aldehyde or ketone group is selected from one or more of diacetone acrylamide, diacetone methacrylamide, diacetone acrylate, diacetone methacrylate, acetoacetoxyethyl acrylate, diacetone vinylamide, acrolein.

Preferably, the compound containing two or more hydrazide groups is a water-soluble dihydrazide compound, preferably the water-soluble dihydrazide compound is a dihydrazide of an aliphatic dicarboxylic acid having 2 to 10 carbon atoms, further preferably the water-soluble dihydrazide compound is oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide and/or itaconic acid dihydrazide.

Preferably, the acidic substance is selected from inorganic acids, organic acids or salts acidic in aqueous solution, such as one or more selected from hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, p-toluenesulfonic acid, citric acid, formic acid, acetic acid, potassium dihydrogen phosphate, ammonium chloride, calcium chloride and monosodium citrate, and particularly preferably from one or more selected from hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, p-toluenesulfonic acid, citric acid, formic acid and acetic acid.

Preferably, the pH of the second component is no greater than 3.

Preferably, the two-part aqueous adhesive is a two-part aqueous contact glue.

Preferably, the monomer with aldehyde or ketone group accounts for 0.1-10% of the total mass of the polyacrylate comonomer.

Preferably, the polyacrylate copolymer emulsion is different from the acidic material.

Further, the present invention provides a method of bonding a first surface to a second surface, the method comprising: providing a two-part aqueous adhesive according to the present invention; when the first component and the second component are simultaneously applied to the first surface of at least one substrate, the second surface of at least one substrate is pressed with the first surface, or the first component is coated on the first surface of at least one substrate, the second component is coated on the second surface of at least one substrate, and then the first surface and the second surface are pressed.

Preferably, the substrate is selected from metal, plastic, wood, textile, paper, rubber, synthetic sponge or wall.

Preferably, the method comprises the steps of spraying the first component and the second component on the first surface of at least one substrate through two nozzles simultaneously, and then pressing the second surface of at least one substrate and the first surface.

The invention also provides an article bonded by the method of bonding a first surface to a second surface.

ADVANTAGEOUS EFFECTS OF INVENTION

Compared with the prior art, the bi-component water-based adhesive uses water as a carrier, and has no environmental pollution in the drying process; according to the invention, the pH value of the second component is accurately regulated by adding an acidic substance, and a process such as spraying is simultaneously applied by combining two components, so that the two-component aqueous adhesive disclosed by the invention is rapidly filmed to generate good initial viscosity, and the chemical crosslinking of the ketone carbonyl group and the hydrazide group ensures that the two-component aqueous adhesive disclosed by the invention has good final viscosity and temperature resistance.

Detailed Description

The technical solution of the present invention will be described in detail with reference to the following examples.

The term "monomer" in the present invention means any chemical species that can be characterized by a chemical formula with polymerizable groups (including (meth) acrylate groups, vinyl ester groups, aromatic vinyl groups) that can be polymerized into oligomers or polymers to increase molecular weight. The molecular weight of the monomers can generally be calculated simply from the given formulae.

The term "aqueous" in the context of the present invention means that the carrier is predominantly water, although organic solvents may also be present, provided that they do not substantially impair the storage stability of the composition. The 'double-component aqueous contact adhesive' of the invention means that the aqueous contact adhesive consists of two components which are respectively and independently stored during storage.

The term "to develop initial adhesion" in the present invention means that the sponge has a spring-open distance of not more than 10mm, preferably not more than 5mm, particularly preferably not more than 2mm within 10 minutes after kneading according to the initial adhesion test method described in the examples.

< two-pack aqueous adhesive >

The invention provides a two-component aqueous adhesive comprising a first component and a second component. When the two-component aqueous adhesive is used, the component (a) and the component (B) are essential components, but it is not limited that the third component is used at the same time. The two-component aqueous adhesive of the invention can be used as a two-component aqueous contact adhesive, i.e. the first component and the second component come into contact with one another and can develop tack when applied to a substrate to be bonded.

The first component of the present invention comprises at least one compound having two or more hydrazide groups, which mainly functions as a crosslinking agent. Preferably, the compound containing two or more hydrazide groups is a water-soluble dihydrazide compound, preferably the water-soluble dihydrazide compound is a dihydrazide of an aliphatic dicarboxylic acid having 2 to 10 carbon atoms, further preferably the water-soluble dihydrazide compound is oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide and/or itaconic acid dihydrazide. Adipic acid dihydrazide is more preferable for further improving initial and final tack and increasing the degree of crosslinking. Because the compound containing two or more hydrazide groups mainly performs a chemical reaction with aldehyde or ketone groups to perform a crosslinking function, the ratio of the number of moles of hydrazide groups in the added compound containing two or more hydrazide groups to the number of moles of aldehyde or ketone groups used can be 0.2-5, and a more preferable ratio is 0.5-3. In a specific embodiment of the present invention, the compound having two or more hydrazide groups is added in an amount of 0.1 to 2% by mass based on the total mass of the first component. If the amount of the hydrazide compound to be added is too small, the degree of crosslinking is affected, and the initial tack, the final tack and the temperature resistance are adversely affected. If the amount of the hydrazide compound added is too high, crosslinking proceeds too quickly, and initial tackiness decreases too quickly. If the compound does not contain two or more hydrazide groups, the initial tack, final tack and temperature resistance of the adhesive are poor or even unusable due to the lack of chemical crosslinking.

The first component of the present invention may be an aqueous solution or emulsion, that is, the first component includes, in addition to a compound having two or more hydrazide groups, a large amount of pure water or a polymer emulsion such as a polyacrylate copolymer emulsion obtained by copolymerizing monomers having aldehyde or ketone groups. The amount of pure water or polymer emulsion added is preferably 85 to 99.5% based on the total mass of the first component. In addition, a small amount of emulsifier, tackifying resin, film forming additive, dispersant, pH regulator, defoaming agent, thickener, color paste, wetting agent and other components can be added according to actual needs, wherein the emulsifier can be selected from ionic emulsifier, the tackifying resin can be selected from water-based rosin resin, the film forming additive can be selected from polyol ester, the dispersant can be selected from polyacrylic acid, the pH regulator can be selected from ammonia water, the defoaming agent can be selected from mineral oil type defoaming agent, the thickener can be selected from polyurethane type thickener, and the wetting agent can be selected from succinic acid sulfonate type.

The pH of the first component of the present invention is not particularly limited, and if a polyacrylate copolymer emulsion is prepared by copolymerizing a monomer having no aldehyde or ketone group in the first component, the pH of the first component may be not more than 4. However, if the pH of the first component is not less than 7 from the viewpoint of reducing the hydrolysis of the hydrazide, it is preferable. When the first component contains a polyacrylate copolymer emulsion prepared by copolymerizing monomers having aldehyde or ketone groups, the pH value of the first component is preferably not less than 7, and particularly preferably 7 to 9, from the viewpoint of maintaining the stability of the emulsion.

At least one acidic substance is added into the second component, the pH value of the second component is not more than 4, and the pH value of the system is mainly adjusted when the two-component water-based adhesive is used. There is no particular limitation in particular as to the kind and amount of the acidic substance as long as the acidic substance added can effectively bring the pH of the second component within the specified range. The acidic substance may be selected from inorganic acids, organic acids or salts acidic in aqueous solution, such as one or more selected from hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, p-toluenesulfonic acid, citric acid, formic acid, acetic acid, monopotassium phosphate, ammonium chloride, calcium chloride, monosodium citrate, particularly preferably from one or more selected from hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, p-toluenesulfonic acid, citric acid, formic acid, acetic acid. From the viewpoint of increasing initial viscosity, the pH of the second component is preferably not more than 3, and further preferably not more than 2.5. If the pH of the second component is greater than 4, the initial tack of the adhesive is affected.

The second component of the present invention may also be an aqueous solution or emulsion, that is, besides containing an acidic substance, pure water or a polymer emulsion such as a polyacrylate copolymer emulsion prepared by copolymerizing monomers having aldehyde or ketone groups, wherein the polyacrylate copolymer emulsion may also exhibit acidity, but in order to achieve rapid adjustment of the pH of the system, the second component still needs to be added with the aforementioned acidic substance such as hydrochloric acid. In addition, the second component can also be added with a small amount of emulsifier, tackifying resin, film forming auxiliary agent, dispersant, pH regulator, defoamer, thickener, color paste, wetting agent and other components according to actual needs, wherein the emulsifier can be selected from ionic emulsifier, the tackifying resin can be selected from water-based rosin resin, the film forming auxiliary agent can be selected from polyol ester, the dispersant can be selected from polyacrylic acid, the pH regulator can be selected from ammonia water, the defoamer can be selected from mineral oil type defoamer, the thickener can be selected from polyurethane type thickener, and the wetting agent can be selected from succinic acid sulfonate type.

The two-component aqueous adhesive of the present invention does not use neoprene, and the polymer that plays a major role in the present invention is derived from a polyacrylate copolymer emulsion prepared by copolymerizing monomers having aldehyde or ketone groups, which is present in the first component and/or the second component of the present invention.

Basic substances may be used as needed to raise the pH of the aqueous binder, and preferred basic substances are ammonia, organic amines such as ethanolamine, AMP-95, metal hydroxides, metal (bi) carbonates, and the like.

The polyacrylate copolymer emulsion is prepared by a conventional emulsion polymerization method, wherein a mixed monomer of a monomer containing an aldehyde or ketone group and other monomers is prepared into a pre-emulsion, and polymerization is carried out at 50-90 ℃ by using a catalyst such as ammonium persulfate. Polyacrylate copolymer emulsions meeting the requirements of the present invention are also commercially available.

Preferably, the monomer having an aldehyde or ketone group is selected from one or more of diacetone acrylamide, diacetone methacrylamide, diacetone acrylate, diacetone methacrylate, acetoacetoxyethyl acrylate, diacetone vinylamide, acrolein, and in one embodiment of the present invention, the monomer having an aldehyde or ketone group is selected from diacetone acrylamide. The addition amount of the monomer with aldehyde or ketone groups is 0.1-10% relative to the total mass of the comonomers, the preferable addition amount is 0.5-5%, when the addition amount of the monomer with aldehyde or ketone groups is less than 0.1%, the final viscosity of the adhesive is poor, if the comonomer with aldehyde or ketone groups is not added, the initial viscosity, the final viscosity and the temperature resistance of the adhesive are poor due to lack of chemical crosslinking effect, and even the adhesive cannot be used, and if the addition amount of the monomer with aldehyde or ketone groups is more than 10%, the initial viscosity of the product is seriously attenuated due to too fast crosslinking speed, and the initial viscosity of the adhesive is badly influenced.

The other monomers in the mixed monomers mainly include alkyl acrylate and alkyl methacrylate monomers such as methyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, ethyl acrylate, isooctyl acrylate, and the like, and are added in an amount of 90 to 99.9% with respect to the total mass of the monomers. In addition, the mixed monomers may also include vinyl aromatic compounds such as styrene, vinyl carboxylates such as vinyl acetate, and other ethylenically unsaturated monomers such as (meth) acrylic acid and the like.

Wherein the polyacrylate copolymer emulsion has a solids content of 20 to 60% and the polymer particles contained in the emulsion have an average particle size (Z-average value measured by dynamic light scattering) of less than 500nm, in particular less than 250 nm. If the average particle size is more than 500nm, the initial tack performance of the adhesive is adversely affected. The polyacrylate copolymer emulsion contains a polymer having a glass transition temperature (measured using a differential thermal scanner) of-50 to 0 deg.C, preferably-40 to-10 deg.C. If the glass transition temperature is less than-50 ℃, the final tack and temperature resistance of the adhesive are adversely affected, and if the glass transition temperature is greater than 0 ℃, the initial tack of the adhesive is adversely affected.

In one embodiment of the invention, the first component of the two-component aqueous binder is an emulsion comprising essentially a polyacrylate copolymer emulsion prepared by copolymerization of monomers having aldehyde or ketone groups and additionally a compound having two or more hydrazide groups at a pH of not less than 7, and the second component is an aqueous solution containing an acidic substance at a pH of not more than 4; in another embodiment of the invention, the first component of the two-component aqueous binder is an aqueous solution containing a compound having two or more hydrazide groups, the second component is an emulsion comprising essentially a polyacrylate copolymer emulsion prepared by copolymerizing monomers having aldehyde or ketone groups, and additionally an acidic substance, and has a pH of not more than 4; in addition, the invention also comprises a technical scheme that the first component and the second component are both emulsions, the first component mainly comprises polyacrylate copolymer emulsion prepared by copolymerizing monomers with aldehyde or ketone groups, and a compound containing two or more hydrazide groups and having a pH value of not less than 7, and the second component mainly comprises polyacrylate copolymer emulsion prepared by copolymerizing monomers with aldehyde or ketone groups and additionally contains an acidic substance and has a pH value of not more than 4. The first option can be selected from the viewpoint of simplification of the production process.

In addition, according to the actual use requirement, a small amount of a third component, such as an antifoaming agent, a thickening agent, a color paste, a wetting agent, an aqueous tackifying resin and other auxiliaries can be added into the two-component aqueous adhesive.

< method of surface adhesion and adhesive article thereof >

The present invention also provides a method of bonding a first surface to a second surface, the method comprising: providing a two-part aqueous adhesive of the present invention; when the first component and the second component are simultaneously applied to the first surface of at least one substrate, the second surface of at least one substrate is then either pressed against the first surface to create an initial adhesion, or the first component is applied to the first surface of at least one substrate, the second component is applied to the second surface of at least one substrate, and the first surface and the second surface are then pressed together to create an initial adhesion.

Preferably, the method comprises the steps of spraying the first component and the second component on the first surface of at least one substrate through two nozzles simultaneously, and then pressing the second surface of at least one substrate and the first surface to generate initial adhesion.

The mixing ratio of the first component and the second component at the time of application (including coating), for example, at the time of ejection from a nozzle is 1:100 to 100:1 (in terms of liquid mass), preferably 10:1 to 1:10, and particularly preferably 4:1 to 1: 4.

Preferably, the application sizing amount (based on the dry glue mass) of the aqueous adhesive is selected differently according to different substrates, and the typical sizing amount is 10-200 g/m²More preferably 30 to 100g/m²。

The invention also provides a product which is obtained by bonding the two-component water-based adhesive by using the bonding method. In one embodiment of the present invention, the two-component aqueous adhesive of the present invention can be used for permanent bonding and shaping of soft materials such as sofas, mattresses, bags and the like by the above-mentioned bonding method of the present invention.

Examples

The present invention is described below by way of examples, which are not exhaustive, as those skilled in the art will appreciate that the examples are illustrative only.

The emulsions D608, D618 and D628 used in this example are those from Bairand technologies, Beijing, the emulsion AV215ap is that from Pasteur, and the emulsions XP 2694 and C84 are those from Corseus. The technical description of the publication is as follows:

the name of the product is: d608

Description of the drawings: a cross-linkable polyacrylate emulsion can be used with adipic acid dihydrazide.

Solid content: 48 to 52 percent

pH：2.5～3.5

Viscosity: <500cps

Average particle size: <250nm

Crosslinking group: diacetone acrylamide, the content is 1 to 3 percent

The name of the product is: d618

Solid content: 48 to 52 percent

pH：7～8

Viscosity: <500cps

Average particle size: <250nm

Crosslinking group: diacetone acrylamide, the content is 1 to 3 percent

The name of the product is: d628

Solid content: 48 to 52 percent

pH：7～8

Viscosity: <500cps

Average particle size: <250nm

Crosslinking group: diacetone acrylamide, the content is 10 to 12 percent

The name of the product is:

AV215ap

description of the drawings: high performance general purpose polyacrylate adhesives.

Solid content: 69 percent

Crosslinking group: is free of

The name of the product is:

C XP 2694

description of the drawings: an aqueous colloidal dispersion of a chloroprene polymer having a strong tendency to crystallize.

Solid content: > 28%

Viscosity (LV/Sp2/60rpm/25 ℃) of <30 mPas

pH:8～10

The name of the product is:

C 84

description of the drawings: aqueous polychloroprene colloidal dispersions having a high crystallization rate, which have a strong tendency to crystallize.

Solid content: 54.5 to 55.5 percent

Viscosity (LV/Sp2/60rpm/25 ℃) of 100 mPas

pH:～13

Example 1

A first component: 10g of adipic acid dihydrazide are weighed out and added to 1000g of pure water.

A second component: 1000g D618 was weighed out and a 1N hydrochloric acid solution was slowly added dropwise with stirring to a pH of 4, and the solution was brought to 40% solids with stirring.

Example 2

A first component: 20g of adipic acid dihydrazide are weighed out and added to 1000g of pure water.

Example 3

A second component: 1000g D618 was weighed out and a 1N hydrochloric acid solution was slowly added dropwise with stirring to a pH of 3, and the solution was brought to 40% solids with stirring.

Example 4

A second component: 1000g D618 was weighed out and a 1N hydrochloric acid solution was slowly added dropwise with stirring to a pH of 2, and the solution was brought to 40% solids with stirring.

Example 5

A second component: 1000g D618 was weighed out and a 2% strength phosphoric acid solution was slowly added dropwise with stirring to a pH of 4, and the solution was brought to 40% solids with stirring.

Example 6

A second component: 1000g D618 was weighed out, a 2% strength phosphoric acid solution was slowly added dropwise with stirring to a pH of 3, and the solution was brought to 40% solids with stirring.

Example 7

A second component: 1000g D618 was weighed out, a 2% strength phosphoric acid solution was slowly added dropwise with stirring to a pH of 2, and the solution was brought to 40% solids with stirring.

Example 8

A second component: 1000g D618 was weighed, and a 10% strength citric acid solution was slowly added dropwise with stirring to a pH of 4, and the resulting solution was stirred with pure water to a solids content of 40%.

Example 9

A second component: 1000g D618 was weighed, a 10% strength citric acid solution was slowly added dropwise with stirring to a pH of 3, and the resulting solution was stirred with pure water to a solids content of 40%.

Example 10

A second component: 1000g D618 was weighed, a 10% strength citric acid solution was slowly added dropwise with stirring to a pH of 2, and the resulting solution was stirred with pure water to a solids content of 40%.

Example 11

A first component: 5g of adipic acid dihydrazide are weighed out and added to 1000g of pure water.

Example 12

Example 13

A first component: 2.5g of adipic dihydrazide are weighed out and added to 1000g of pure water.

Example 14

Example 15

A first component: 1000g D618 g of adipic acid dihydrazide (10 g) were weighed out, stirred and the solution obtained was brought to 40% solids with pure water and adjusted to pH 7.5.

A second component: 1000g of pure water were weighed and a 1N hydrochloric acid solution was slowly added dropwise with stirring to a pH of 4.

Example 16

A first component: 1000g D618 was weighed in, 5g of adipic dihydrazide were added with stirring, and the resulting solution was brought to 40% solids with stirring with pure water and adjusted to pH 7.5.

A second component: 1000g of pure water were weighed and a 1N hydrochloric acid solution was slowly added dropwise with stirring to a pH of 2.

Example 17

A second component: 1000g of pure water were weighed and a 1N hydrochloric acid solution was slowly added dropwise with stirring to a pH of 3.

Example 18

Example 19

A second component: 1000g of pure water was weighed and a 10% citric acid solution was slowly added dropwise with stirring to a pH of 4.

Example 20

A second component: 1000g of pure water was weighed and a 10% citric acid solution was slowly added dropwise with stirring to a pH of 3.

Example 21

A second component: 1000g of pure water was weighed and a 10% citric acid solution was slowly added dropwise with stirring to a pH of 2.

Example 22

A second component: 1000g of pure water were weighed and a 2% strength phosphoric acid solution was slowly added dropwise with stirring to a pH of 4.

Example 23

A second component: 1000g of pure water were weighed and a 2% strength phosphoric acid solution was slowly added dropwise with stirring to a pH of 3.

Example 24

A second component: 1000g of pure water were weighed and a 2% strength phosphoric acid solution was slowly added dropwise with stirring to a pH of 2.

Example 25

A first component: 1000g D618 g of adipic acid dihydrazide (20 g) were weighed out, stirred and the solution obtained was brought to 40% solids with pure water and adjusted to pH 7.5.

A second component: 1000g D618 was weighed and a 1N hydrochloric acid solution was slowly added dropwise with stirring to a pH of 3.

Example 26

A second component: 1000g D618 was weighed out and a 2% strength phosphoric acid solution was slowly added dropwise with stirring to a pH of 3.

Example 27

A second component: 1000g D608 was weighed and purified water was added with stirring to 40% solids, pH 3.

Comparative example 1

A second component: 1000g D618 was weighed and a 1N hydrochloric acid solution was slowly added dropwise with stirring to a pH of 4.5, and the solution was brought to 40% solids with stirring.

Comparative example 2

A second component: 1000g D618 was weighed out and pure water was added with stirring to 40% solids and the pH was adjusted to 7.5.

Comparative example 3

A first component: 1000g D618 g of adipic acid dihydrazide (10 g) were weighed in with stirring, and the resulting solution was added neat water with stirring to a 40% solids content, pH 7.5.

A second component: 1000g of pure water was weighed.

Comparative example 4

A first component: 1000g D618 g of adipic acid dihydrazide (20 g) were weighed in with stirring, and the resulting solution was added neat water with stirring to a 40% solids content, pH 7.5.

A second component: 1000g of pure water was weighed.

Comparative example 5

A first component: 1000g of pure water was weighed.

Comparative example 6

A first component: 40g of adipic acid dihydrazide are weighed out and added to 1000g of pure water.

Comparative example 7

A second component: 1000g D628 was weighed out and a 1N hydrochloric acid solution was slowly added dropwise with stirring to a pH of 4, and pure water was added to the solution with stirring to a solids content of 40%.

Comparative example 8

A first component: 1000g of C XP 2694 were weighed in.

A second component: 1000g of C XP 2694 were weighed in.

Comparative example 9

A first component: 1000g C84 was weighed and pure water was added with stirring to 40% solids.

Comparative example 10

A first component: pure water.

A second component: 1000g C84 was weighed and a 1N hydrochloric acid solution was slowly added dropwise with stirring to a pH of 4, and the resulting solution produced a large amount of solid matter, which was not amenable to subsequent experiments.

Comparative example 11

A first component: 10g of adipic dihydrazide are weighed out and added to 1000g of pure water with stirring.

A second component: 1000g of AV215ap were weighed out, a 1N hydrochloric acid solution was slowly added dropwise with stirring to a pH of 2, and the solution obtained was brought to 40% solids with stirring.

Comparative example 12

A first component: 1000g of AV215ap were weighed in, 10g of adipic acid dihydrazide were added with stirring, and the resulting solution was added with pure water with stirring to 40% solids.

Comparative example 13

A first component: 1000g of AV215ap were weighed in and pure water was added with stirring to 40% solids content.

Performance evaluation

Polyurethane sponge (density 25 kg/m)³) Cutting into cuboid of 10cm × 10cm × 5cm, placing on table, spraying the first component and the second component onto the surface of sponge (10cm × 5 cm) at a ratio of 1:1 (by mass liquid) by using S2-K type (Schutze) two-component spray gun, and applying 50g/m of glue². After waiting for 1 minute, the sponge was folded over the rectangular face of the two-component aqueous adhesive along the center line of the 5cm side so that the glue-sprayed surfaces were adhered together, and kneaded with fingers.

Initial viscosity evaluation: the length of the bound sponge in mm after 10 minutes after the sponge was kneaded was recorded, and if it was fully opened, it was recorded as fully opened.

Evaluation of final viscosity: the kneaded sponge was left to stand at room temperature for 3 days while being kept in a pressed state, peeled from the bonded part, and the peel failure mode was recorded. The failure mode is that sponge tearing is recorded as passing, and the failure mode is that the adhesive layer peeling is recorded as not passing.

And (3) evaluating the temperature resistance: the kneaded sponge was left to stand at room temperature for 3 days while being kept in a pressed state, and then placed in an oven at 110 ℃ for 8 hours, and whether the sponge was flicked or not was recorded as passed, and flicked or partially flicked was recorded as not passed.

The adhesives of examples 1 to 27 and comparative examples 1 to 13 were subjected to a performance test using the above-described performance evaluation method, and the test results are shown in tables 1 and 2.

TABLE 1 results of the Performance test of examples 1-27

	Initial tack (mm)	Final tack	Temperature resistance
				Target value	≤10	By passing	By passing
Example 1	4	By passing	By passing
				Example 2	3	By passing	By passing
Example 3	2	By passing	By passing
				Example 4	0	By passing	By passing
Example 5	4	By passing	By passing
				Example 6	2	By passing	By passing
Example 7	0	By passing	By passing
				Example 8	4	By passing	By passing
Example 9	2	By passing	By passing
				Example 10	0	By passing	By passing
Example 11	4	By passing	By passing
				Example 12	0	By passing	By passing
Example 13	8	By passing	By passing
				Example 14	4	By passing	By passing
Example 15	4	By passing	By passing
				Example 16	0	By passing	By passing
Example 17	2	By passing	By passing
				Example 18	0	By passing	By passing
Example 19	4	By passing	By passing
				Example 20	2	By passing	By passing
Example 21	0	By passing	By passing
				Example 22	4	By passing	By passing
Example 23	2	By passing	By passing
				Example 24	0	By passing	By passing
Example 25	2	By passing	By passing
				Example 26	2	By passing	By passing
Example 27	6	By passing	By passing

TABLE 2 results of the Performance test of comparative examples 1 to 13

As can be seen from a comparison of tables 1 and 2, only the first and second components of the two-component aqueous adhesive according to the requirements of the present invention achieve good initial tack, final tack and temperature resistance after simultaneous spraying. If the pH of the second component is greater than 4, as in comparative example 1(pH 4.5) or comparative example 2(pH 7.5), the initial tack of the adhesive is poor; if the hydrazide compound is not added to the first component as in comparative example 5, or if the polyacrylate emulsion of the first or second component does not contain an aldehyde or ketone group comonomer as in comparative examples 12 to 14, the initial tack, final tack and temperature resistance of the adhesive are poor due to the lack of crosslinking. If the conventional water-based polychloroprene colloidal dispersion on the market is adopted to replace polyacrylate emulsion as a main component of the adhesive, although the initial viscosity and the final viscosity of the adhesive can meet the requirement, the temperature resistance is poor, and if an acidic substance is added into the conventional water-based polychloroprene colloidal dispersion on the market, the adhesive is demulsified and cannot be used.

However, the above description is only a preferred embodiment of the present invention, and it is natural that those skilled in the art can change the present invention based on the actual requirement after understanding the technical means of the present invention. Therefore, all equivalent changes and modifications made in accordance with the claims of the present invention should still fall within the scope of the present invention.

Claims

1. A two-part aqueous adhesive characterized by:

the two-component aqueous adhesive comprises a first component and a second component,

said first component comprising at least one compound containing two or more hydrazide groups;

at least one acidic substance is added into the second component, and the pH value of the second component is not more than 2.5;

at least one of the first component and the second component also contains polyacrylate copolymer emulsion prepared by copolymerizing monomers with aldehyde or ketone groups;

the acidic substance is selected from one or more of hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, p-toluenesulfonic acid, citric acid, formic acid and acetic acid;

the mixing ratio of the first component to the second component during application is 1: 1-1: 4 in terms of liquid mass.

2. The two-component aqueous adhesive of claim 1, wherein:

the monomer with aldehyde or ketone groups is selected from one or more of diacetone acrylamide, diacetone methacrylamide, diacetone acrylate, diacetone methacrylate, acetoacetoxyethyl acrylate, diacetone vinyl amide and acrolein.

3. A two-component aqueous adhesive according to claim 1 or 2, characterized in that:

the compound containing two or more hydrazide groups is a water-soluble dihydrazide compound.

4. A two-component aqueous adhesive according to claim 3, characterized in that:

the water-soluble dihydrazide compound is a dihydrazide of an aliphatic dicarboxylic acid of 2 to 10 carbon atoms.

5. The two-component aqueous adhesive of claim 4, wherein:

the water-soluble dihydrazide compound is oxalic dihydrazide, malonic dihydrazide, succinic dihydrazide, glutaric dihydrazide, adipic dihydrazide, sebacic dihydrazide, maleic dihydrazide, fumaric dihydrazide and/or itaconic dihydrazide.

6. A two-component aqueous adhesive according to claim 1 or 2, characterized in that: the monomer with aldehyde or ketone groups accounts for 0.1-10% of the total mass of the polyacrylate comonomer.

7. A two-component aqueous adhesive according to claim 1 or 2, characterized in that: the polyacrylate copolymer emulsion is different from the acidic material.

8. A method of bonding a first surface to a second surface, the method comprising: providing a two-component aqueous adhesive according to any one of claims 1 to 7; the first component and the second component are simultaneously applied to a first surface of at least one substrate, and then a second surface of the at least one substrate is pressed with the first surface, or the first component is applied to the first surface of the at least one substrate, and the second component is applied to the second surface of the at least one substrate, and then the first surface and the second surface are pressed.

9. The method of claim 8, wherein the substrate is selected from the group consisting of metal, plastic, wood, textile, paper, rubber, synthetic sponge, and wall.

10. The method according to claim 8 or 9, wherein the method comprises spraying the first component and the second component onto a first surface of at least one substrate simultaneously through two nozzles, and then pressing the second surface of at least one substrate against the first surface.

11. An article bonded by the method of any of claims 8-10.