Modified rubber emulsion and aqueous adhesive composition

Abstract

The present invention relates to the technical field of aqueous adhesives, and specifically relates to a modified rubber emulsion and an aqueous adhesive composition. The raw materials for the preparation thereof at least comprise, in percentages by mass: 10-70% of a modified rubber solution, 0.01-5% of a surfactant, and the balance of water, wherein the modified rubber solution is prepared by modifying a halogenated elastomer with a modifier. The aqueous adhesive composition prepared by using the modified rubber emulsion effectively satisfies the requirements of bonding application between a metal and an elastomer. The product is environmentally friendly and has excellent stability, and also possesses the performance of bonding a substrate to an elastomer by means of a single coat, thereby having an extremely high market application and promotion value.

Description

Modified rubber latex, water-based adhesive composition Technical Field

[0001] This invention relates to the field of water-based adhesives, specifically to modified rubber latexes and water-based adhesive compositions. Background Technology

[0002] Many commercially available compositions for bonding metal-elastomers are dissolved in organic solvents, which can harm the environment and potentially affect the health of workers exposed to these solvents. Given the increasing awareness of environmental protection and safety, there is an urgent need for low-VOC or VOC-free adhesive compositions to avoid the use of organic solvents. However, most current water-based adhesive compositions for bonding metal-elastomers do not meet the requirement of ≤50 g / L volatile organic compound content as stipulated in GB33372-2020, and some even contain chlorinated solvents (the US has revised its Toxic Substances Control Act regarding dichloromethane, explicitly prohibiting its industrial and commercial use; the EU's revised Registration, Evaluation, Authorization and Restriction of Chemicals also imposes restrictions on chlorinated solvents such as dichloromethane, chlorobenzene, and chloroform). Therefore, developing a water-based adhesive composition that complies with relevant laws and regulations is essential.

[0003] Currently, there are two main systems in waterborne adhesives. One is a waterborne adhesive mainly composed of dichlorobutadiene as the main monomer, copolymer emulsions, acid scavengers, nitrosamines, and film-forming agents. The other is a waterborne adhesive mainly composed of halogenated polyolefin emulsions, acid scavengers, nitrosamines, and maleimide compounds. The former exhibits excellent performance in terms of adhesion to natural rubber, short-term environmental resistance, and storage stability, but its versatility in bonding elastomers is problematic, and most adhesives contain chlorinated solvents. For example, Chinese Patent (Publication No. CN1135224A) discloses an adhesive composition containing a polyvinyl alcohol-stabilized butadiene copolymer emulsion and a methylene donor; US Patent (Publication No. US8501853B2) discloses an adhesive composition containing butadiene polymer latex, acid-scavenging compounds, and compounds that substantially do not contain phenolic resin or methylene donors (γ-PO). Aqueous adhesive compositions containing M); US Patent (Publication No. US4483962) discloses a ternary polymer latex prepared by emulsion polymerization of a mixture of 2,3-dihalo-1,3-butadiene and at least two different unsaturated monomers; Chinese Patent (Publication No. CN1135224A) discloses an adhesive composition containing butadiene polymer latex stabilized with polyethanol and a methylene donor compound, etc., which have the problems of easy adhesion failure when bonding non-polar rubber, limited types of elastomers that can be bonded, and lack the ability to bond substrates and elastomers with a single coating. The latter has better environmental resistance and is more universal in its selection of elastomers, but it differs in storage stability and high-temperature resistance. In addition, it cannot achieve the same performance as solvent-based adhesive compositions in terms of the performance of bonding substrates and elastomers when applied alone. For example, Chinese patent (authorization announcement number CN101182404B) discloses a water-based adhesive composition; Chinese patent (authorization announcement number CN112585229B) discloses a water-based adhesive film-forming coating composition; Chinese patent (authorization announcement number CN1908105B) discloses a water-based composition as an adhesive; Chinese patent (authorization announcement number CN1055488C) discloses a water-based adhesive composition containing a chlorosulfonated polyethylene latex, a polymaleimide compound, a nitroso compound, and a metal oxide, etc. However, it lacks resistance to harsh environments and has relatively poor storage stability, failing to achieve the 12-month shelf life expected by customers.

[0004] Therefore, current water-based adhesive compositions have significant shortcomings in terms of adhesive performance compared to conventional solvent-based adhesive compositions, and cannot provide the same adhesive performance as solvent-based adhesives to meet the bonding application requirements between metals and elastomers. Summary of the Invention

[0005] To address the aforementioned issues, this invention provides a modified rubber latex. Aqueous adhesive compositions prepared using this modified rubber latex effectively meet the bonding application requirements between metals and elastomers. The products are environmentally friendly and exhibit excellent stability, while also possessing the ability to bond substrates and elastomers with a single coating, thus possessing extremely high market application and promotion value.

[0006] The present invention provides a modified rubber emulsion, the raw materials for which, by mass percentage, are at least: 10-70% modified rubber solution, 0.01-5% surfactant, and water to make up the balance, wherein the modified rubber solution is prepared by modifying a halogenated elastomer with a modifier.

[0007] As a preferred technical solution, the modified rubber emulsion, by mass percentage, comprises at least: 40-60% modified rubber solution, 0.5-5% surfactant, and water to make up the balance.

[0008] Most preferably, the modified rubber emulsion is prepared by means of the following raw materials by mass percentage: 49.00% modified rubber solution, 1.00% surfactant A, and water to make up the balance.

[0009] As a preferred technical solution, the raw materials for preparing the modified rubber solution include at least the following components by mass percentage: 10-20% halogenated elastomer, 0.5-2% modifier, and solvent to make up the balance.

[0010] As a preferred technical solution, the halogenated elastomer is selected from at least one of halogenated natural rubber and halogen-containing synthetic rubber.

[0011] Preferably, the halogen-containing synthetic rubber includes at least one of polychloroprene, halogenated polychloroprene, halogenated polybutadiene, hexachloropentadiene, butadiene-halogenated cyclic conjugated diene adduct, halogenated butadiene-styrene copolymer, halogenated ethylene-propylene copolymer, ethylene-propylene-nonconjugated diene terpolymer, halogenated polyethylene, halogenated sulfonated polyolefin, halogenated poly(2,3-dichloro-1,3-butadiene), copolymer of α-haloacrylonitrile and 2,3-dichloro-1,3-butadiene, and halogenated polyvinyl chloride, preferably halogenated sulfonated polyolefin.

[0012] Preferably, the halosulfonated polyolefin includes at least one of chlorosulfonated polyethylene, bromosulfonated polyethylene, chlorosulfonated polypropylene, and bromosulfonated polypropylene, and is more preferably chlorosulfonated polyethylene or bromosulfonated polyethylene.

[0013] Preferably, the weight-average molecular weight of the chlorosulfonated polyethylene is 30,000 to 150,000, and more preferably 60,000 to 120,000.

[0014] Preferably, the Mooney viscosity (ML(1+4)@100℃) of the chlorosulfonated polyethylene is 45-100, more preferably 45-60.

[0015] Preferably, the chlorine content of the chlorosulfonated polyethylene is 20-50 wt%, more preferably 30-40 wt%.

[0016] Preferably, the sulfur content of the chlorosulfonated polyethylene is 0.25-5 wt%, more preferably 0.8-2.0 wt%.

[0017] As a preferred technical solution, the modifier is selected from at least one of the structures shown in formulas (1) to (4).

[0018] Equation (1): R-OH, where R represents C1~C 40 Straight-chain or branched n-valent alkyl groups, C2-C 30 n-valent straight-chain or branched alkenyl groups, C3-C 30 n-valent straight-chain or branched alkynyl groups, C6-C 40 The n-valent aryl group; any -H or -CH3 in R can be replaced by an oxygen atom, a halogen atom, a cyano group, or a methoxy group.

[0019] It should be noted that the "n-valent" in the term "n-valent alkyl" refers to the presence of n substituents on the alkyl group. Similarly, "n-valent alkenyl" and "n-valent alkynyl" respectively indicate that the alkenyl group and the alkynyl group have n substituents. All other expressions of "n-valent groups" in this patent are interpreted in the same way.

[0020] Preferably, formula (1) includes at least one of methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, tert-butanol, 2-(2-ethoxyethoxy)ethanol, 2-(2-butoxyethoxy)ethanol, 2-(2-methoxyethoxy)ethanol, 2-methoxyethanol, 2-butoxyethanol, 2-ethoxyethanol, 2-butoxypropanol, 2-butoxyethoxyethanol, 2-bromopropanol, 3-bromopropanol, propoxypropanol, propylene glycol monomethyl ether, n-dodecyl alcohol, 4-butyn-1-ol, polyethylene glycol monomethyl ether, ethanolamine, propanolamine, and isopropanolamine.

[0021] Equation (2): Where R1 represents C1~C 40 Straight-chain or branched n-valent alkyl groups, C2-C 30 n-valent straight-chain or branched alkenyl groups, C3-C 30 n-valent straight-chain or branched alkynyl groups, C6-C 40The n-valent aryl group, R2 represents a methyl or hydrogen atom; any -H in R1 can be replaced by a halogen atom, any -CH3 in R1 can be replaced by a methoxy or cyano group, and any -CH2- in R1 can be replaced by an oxygen atom or a sulfur atom.

[0022] Preferably, formula (2) includes at least one of hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate.

[0023] Equation (3):

[0024] Equation (4): Where R represents C1~C 40 Straight-chain or branched n-valent alkyl groups, C2-C 30 n-valent straight-chain or branched alkenyl groups, C3-C 30 The n-valent straight-chain or branched alkynyl group and halogen atom; any -H or -CH3 in R can be replaced by an oxygen atom, halogen atom, cyano group, or methoxy group.

[0025] Preferably, formula (4) includes at least one of phthalamide, 4-methylphthalamide, 3-ethylphthalamide, N-hydroxyethylmaleimide, and 1-hydroxy-1H-pyrrole-2,5-dione.

[0026] As a preferred technical solution, the modifier is selected from any one of anhydrous ethanol, anhydrous methanol, polyethylene glycol monomethyl ether, ethanolamine, maleimide, hydroxyethyl acrylate, 2-bromoethanol, and 3-hydroxypropionitrile.

[0027] As a preferred technical solution, the solvent includes at least xylene.

[0028] As a preferred technical solution, the raw materials for preparing the modified rubber solution also include an alkaline catalyst.

[0029] As a preferred technical solution, the alkaline catalyst is selected from at least one of amino metal compounds, alkaline metal hydroxides, alkaline metal carbonates, alkaline metal bicarbonates, and alkaline organic amine compounds.

[0030] Preferably, the alkaline catalyst is selected from at least one of lithium isopropylaminolithium, lithium hexamethylenedisilaminolithium, lithium trisilylaminolithium, lithium hydroxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, calcium bicarbonate, potassium bicarbonate, triethylamine, and diethylamine.

[0031] As a preferred technical solution, the molar ratio of the alkaline catalyst to the modifier is (1-5):1, preferably (1-1.2):1.

[0032] As a preferred technical solution, the method for preparing the modified rubber solution includes the following steps: mixing the raw materials for preparing the modified rubber solution and reacting them at 30-100℃ for 3-10 hours to obtain the modified rubber solution.

[0033] Preferably, the reaction temperature is 50–90°C and the reaction time is 5–8 hours.

[0034] The surfactant A is selected from at least one of the following: carboxylates, acyl derivatives of sarcosine, sulfates, sulfated natural oil esters, alkyl aryl polyether sulfates, alkali metal alkyl sulfates, ethoxylated aryl sulfonates, alkyl aryl polyacryl sulfonates, isopropylbenzene sulfonates, sulfosuccinates, phosphate esters, ethoxylated (ethylene oxide) derivatives, alcohols, ethylene oxide / propylene oxide block copolymers, stearates, dehydration products of sorbitol, amines, lauric acid, and isopropylene halides.

[0035] Examples of carboxylates include: fatty acid soaps derived from lauric acid, stearic acid, and oleic acid; acyl derivatives of sarcosine, including: methylglycine; sulfates, including: sodium lauryl sulfate; sulfated natural oil esters, including: Turkish red oil; phosphate esters, including: short-chain fatty alcohol fractions of complex phosphates and orthophosphates of polyethoxylated fatty alcohols; stearates, including: glyceryl monostearate; and dehydrated products of sorbitol, including: dehydrated sorbitol monostearate and polyethylene oxide dehydrated sorbitol monolaurate.

[0036] Preferably, the surfactant A is selected from alkyl aryl polyether sulfate; more preferably, it is dodecyl polyethylene glycol sulfate. As a preferred technical solution, the modified rubber emulsion is prepared by adding a modified rubber solution to a solution of surfactant A and water, homogenizing and emulsifying, removing the solvent, and obtaining a modified rubber emulsion with a total solids content of 10-60 wt%.

[0037] Preferably, the conditions for homogenization emulsification include: a rotation speed of 10,000 to 30,000 rpm, a temperature of 50 to 80°C, and a time of 5 to 25 minutes.

[0038] Preferably, the solvent removal method is vacuum distillation, and the conditions for vacuum distillation include: a pressure of 20-40 kPa and a temperature of 50-60°C.

[0039] As a preferred technical solution, the total solid content of the modified rubber latex is 20-50 wt%, preferably 30-45 wt%.

[0040] The modified rubber latex provided by this invention modifies chlorosulfonated polyethylene by using a modifier, particularly anhydrous ethanol, anhydrous methanol, polyethylene glycol monomethyl ether, ethanolamine, maleimide, hydroxyethyl acrylate, 2-bromoethanol, and 3-hydroxypropionitrile, to modify chlorosulfonated polyethylene with a chlorine content of 30-40 wt%, a sulfur content of 0.8-2.0%, and a Mooney viscosity (ML(1+4)@100℃) of 45-100. This significantly improves the bonding performance of water-based adhesive compositions containing this modified rubber latex for use between metals and elastomers.

[0041] Another aspect of the present invention provides an aqueous adhesive composition comprising, by weight percentage, at least the following components: 4.8-14.4% nitrosamines, 2-10% modified rubber latex, and the balance being pure water.

[0042] The aqueous adhesive composition is characterized in that, by mass percentage, it comprises at least the following components: 40-60% mother liquor, 2-10% modified rubber latex, 1-5% halogenated natural rubber latex, and the balance being pure water; the raw materials for preparing the mother liquor, by mass percentage, comprise at least 12-24% nitrosamines, 5-15% adhesion promoters, 8-15% acid binders, 3-18% carbon black, 1-8% dispersants, and the balance being pure water.

[0043] Preferably, the raw materials for preparing the mother liquor, by mass percentage, include at least 20-22% nitrosamines, 10-12% adhesive accelerators, 10-14% acid binders, 5-14% carbon black, 5% dispersants, and the balance being pure water.

[0044] Preferably, the acid-binding agent is selected from at least one of metal oxides, metal phosphates, or lead salts, and is more preferably a metal oxide or a metal phosphate.

[0045] Preferably, the metal oxide is selected from at least one of oxides of zinc, cadmium, magnesium, lead and calcium, and is preferably zinc oxide.

[0046] Preferably, the metal phosphate is selected from at least one of zinc, magnesium, lead and calcium phosphates, and is preferably zinc phosphate.

[0047] Preferably, the lead salt is selected from at least one of lead phthalate, lead maleate monohydrate, lead fumarate, lead phosphite, and basic lead carbonate.

[0048] As a preferred technical solution, the adhesion promoter includes at least a maleamide compound.

[0049] Preferably, the maleamide compound is an aromatic polymaleimide compound, and more preferably an aromatic polymaleimide having 2-200 aromatic nuclei.

[0050] Preferably, the aromatic polymaleimide has the structure shown in formula (4):

[0051] Equation (4): X ranges from 0 to 90, with a preferred value of 0 to 25.

[0052] Aromatic polymaleimides sold by different companies have different trade names, for example: BMI-20-M and BMI-S aromatic polymaleimides sold by Mitsu: Toatsu Fine Chemicals, Incorporated. This invention uses a chemical additive (heat-resistant crosslinking agent - PAPI) formulated by Otsuka Chemical Management Co., Ltd.

[0053] As a preferred technical solution, the nitrosyl group is selected from nitrosyl compounds or nitrosyl compound precursors.

[0054] As a preferred technical solution, the nitroso compound is an aromatic compound containing at least two nitroso groups directly attached to non-adjacent ring carbon atoms.

[0055] Preferably, the nitroso compound is an aromatic compound having 1 to 3 aromatic nuclei (including fused aromatic nuclei) and 2 to 6 nitroso groups directly bonded to non-adjacent nucleus carbon atoms, wherein the nuclear hydrogen atoms on the aromatic nuclei may be substituted by alkyl, alkoxy, cycloalkyl, aryl, aralkyl, alkylaryl, aromatic amine, arylnitroso, amino, or halogen.

[0056] Preferably, the nitroso compound is a dinitroso aromatic compound, preferably at least one of m-dinitrosobenzene, p-dinitrosobenzene, m-dinitrosonaphthalene, p-dinitrosonaphthalene, 2,5-dinitroso-p-methylisopropylbenzene, 2-methyl-1,4-dinitrosobenzene, 2-methyl-5-chloro-1,4-dinitrosobenzene, 2-fluoro-1,4-dinitrosobenzene, 2-methoxy-1,3-dinitrosobenzene, 5-chloro-1,3-dinitrosobenzene, 2-benzyl-1,4-dinitrosobenzene, and 2-cyclohexyl-1,4-dinitrosobenzene.

[0057] Preferably, the nitroso compound includes m-dinitrosobenzene and p-dinitrosobenzene, and the mass ratio of m-dinitrosobenzene to p-dinitrosobenzene is (0.5-2):1, preferably 1:1.

[0058] As a preferred technical solution, the nitroso compound precursor is any compound that can be converted into a nitroso compound by oxidation at 140-200°C.

[0059] Preferably, the nitroso compound precursor is a derivative of a quinone compound, and is preferably at least one of quinone dioxime, dibenzoquinone dioxime, 1,2,4,5-tetrachlorobenzoquinone, 2-methyl-1,4-benzoquinone dioxime, 1,4-benzoquinone dioxime, 1,2-benzoquinone dioxime, and 2,6-benzoquinone dioxime.

[0060] As a preferred technical solution, the raw materials for preparing the halogenated natural rubber emulsion, by weight, include at least: 100-150 parts of chlorinated natural rubber, 200-350 parts of xylene, 5-30 parts of surfactant B, and 400-600 parts of water.

[0061] Preferably, the chlorinated natural rubber has a weight-average molecular weight of 100,000 to 500,000 and a chlorine content of 50 to 70 wt%, more preferably a chlorine content of 60 to 70 wt%.

[0062] The surfactant B is selected from at least one of the following: carboxylates, acyl derivatives of sarcosine, sulfates, sulfated natural oil esters, alkyl aryl polyether sulfates, alkali metal alkyl sulfates, ethoxylated aryl sulfonates, alkyl aryl polyacryl sulfonates, isopropylbenzene sulfonates, sulfosuccinates, phosphate esters, ethoxylated (ethylene oxide) derivatives, alcohols, ethylene oxide / propylene oxide block copolymers, stearates, dehydration products of sorbitol, amines, lauric acid, and isopropylene halides.

[0063] Examples of carboxylates include: fatty acid soaps derived from lauric acid, stearic acid, and oleic acid; acyl derivatives of sarcosine, including: methylglycine; sulfates, including: sodium lauryl sulfate; sulfated natural oil esters, including: Turkish red oil; phosphate esters, including: short-chain fatty alcohol fractions of complex phosphates and orthophosphates of polyethoxylated fatty alcohols; stearates, including: glyceryl monostearate; and dehydrated products of sorbitol, including: dehydrated sorbitol monostearate and polyethylene oxide dehydrated sorbitol monolaurate.

[0064] Preferably, the surfactant B is selected from alkyl aryl polyether sulfate; more preferably, it is dodecylphenol polyoxyethylene ether sulfonate.

[0065] Preferably, the preparation method of the halogenated natural rubber emulsion is as follows: after stirring and mixing chlorinated natural rubber and xylene, it is added to a solution of surfactant B and water, homogenized and emulsified, and the solvent is removed to obtain a halogenated natural rubber emulsion with a total solid content of 10-60 wt%.

[0066] Preferably, the preparation method of the halogenated natural rubber emulsion is as follows: chlorinated natural rubber and xylene are stirred and mixed at 60-85°C for 4-6 hours, and then added to a solution of surfactant B and water. The mixture is homogenized and emulsified for 5-25 minutes using a homogenizer at a speed of 10000-30000 rpm and a temperature of 50-80°C to obtain an emulsion. The emulsion is then heated to 50-60°C under reduced pressure of 20-40 kPa to remove the solvent, thereby obtaining a halogenated natural rubber emulsion with a total solid content of 10-60 wt%.

[0067] Preferably, the total solids content of the halogenated natural rubber emulsion is 20-50 wt%, more preferably 30-45 wt%.

[0068] As a preferred technical solution, the dispersing agent is selected from at least one of sodium lignosulfonate, calcium lignosulfonate, basic lignin, and polycarboxylate, preferably sodium lignosulfonate.

[0069] As a preferred technical solution, the preparation method of the water-based adhesive composition is as follows: the water-based adhesive composition is obtained by stirring and mixing the raw materials of the water-based adhesive composition.

[0070] Preferably, the water-based adhesive composition is prepared by mixing and grinding nitrosamines, acid binders, adhesion promoters, carbon black, dispersants, and pure water until the fineness is <10μm to obtain a mother liquor; the mother liquor, modified rubber latex, halogenated natural rubber latex, and pure water are stirred and mixed to obtain the water-based adhesive composition.

[0071] Preferably, the grinding instruments include: ball mill, sand mill, ceramic bead mill, steel ball mill, and high-speed media mill.

[0072] Preferably, the stirring speed is 60-100 r / min.

[0073] Preferably, the mixing time is 10-60 min, more preferably 20-40 min.

[0074] Preferably, the viscosity of the aqueous adhesive composition (25±1℃, rotational viscometer, #1 rotor at 90 rpm) is 10-200 cps.

[0075] Preferably, the solids content of the aqueous adhesive composition is 10-50 wt%, more preferably 14-28 wt%.

[0076] This invention constructs a modified rubber latex-nitroso compound-adhesion accelerator system, especially by controlling the amount of each raw material added in the mother liquor, so that the provided water-based adhesive composition still exhibits excellent adhesion performance in initial bonding, baking resistance, high-temperature fluid resistance and corrosive environments, and also maintains good adhesion performance in high-temperature environments.

[0077] A third aspect of the present invention provides an elastomer composite material, comprising, from bottom to top, at least a substrate layer, a primer layer, an aqueous adhesive layer, and an elastomer layer.

[0078] As a preferred technical solution, the substrate layer is made of metal.

[0079] As a preferred technical solution, the material of the elastomer layer is NR55, NR70, NBR, SBR, EPDM (Taicang Guanlian Rubber) or one of the three elastomers (WDK1, WDK2, WDK3) specified in the German Rubber Manufacturers Association (WDK).

[0080] As a preferred technical solution, the method for preparing the elastomeric composite material includes:

[0081] The substrate layer is sandblasted or polished and then preheated to 50-100℃ to obtain a pretreated substrate layer; a water-based primer is applied to the surface of the pretreated substrate layer to form a primer layer with an average thickness of 5-15μm; a water-based adhesive composition is applied to the surface of the primer layer preheated to 50-100℃ to form a water-based adhesive layer of 10-35μm; and rubber is molded, injected, or injected onto the water-based adhesive layer at 140-180℃ to obtain an elastomer composite material.

[0082] Preferably, the method for preparing the elastomeric composite material includes:

[0083] The substrate layer is sandblasted or polished and then preheated to 60-90℃ to obtain a pretreated substrate layer; a water-based primer is applied to the surface of the pretreated substrate layer to form a primer layer with an average thickness of 7.5-12.5μm; a water-based adhesive composition is applied to the surface of the primer layer preheated to 60-90℃ to form a water-based adhesive layer of 15-25μm; and rubber is molded, injected, or injected onto the water-based adhesive layer at 150-170℃ to obtain an elastomer composite material.

[0084] Preferably, the coating method is selected from one of spraying, dipping, brushing, wiping, immersion, and roller coating, and is preferably spraying, brushing, or immersion coating.

[0085] When applied by brushing or dip coating, a water-based adhesive composition with a solid content of 25±3wt% yields the best results; when applied by spraying, a water-based adhesive composition with a solid content of 17±3wt% yields the best results.

[0086] The water-based adhesive composition provided by this invention, through optimizing the combination of raw materials in the system, achieves bonding performance that is basically on par with solvent-based adhesives when used for bonding metal substrates and elastomers, while also meeting the bonding requirements of various elastomers, thus having a wider range of applications.

[0087] The water-based adhesive composition provided by this invention can meet the application requirements of rubber composites with semi-effective vulcanization system and rubber composites with effective vulcanization system in the field of automotive NVH. Products bonded with this water-based adhesive composition can be stored stably for a long time in high-temperature fluid and corrosive environments.

[0088] The water-based adhesive composition provided by this invention meets VOC requirements, does not contain chlorinated solvents such as dichloromethane, trichloromethane, and chlorobenzene, and the adhesive composition itself can be stably stored for more than 6 months, better meeting the needs of practical applications. Beneficial effects

[0089] 1. This invention provides a modified rubber latex, and the water-based adhesive composition prepared using this modified rubber latex effectively meets the bonding application requirements between metals and elastomers. The product is environmentally friendly and has excellent stability, and has extremely high market application and promotion value.

[0090] 2. The modified rubber latex provided by the present invention modifies chlorosulfonated polyethylene by using a modifier, especially by using any one of anhydrous ethanol, anhydrous methanol, polyethylene glycol monomethyl ether, ethanolamine, maleimide, hydroxyethyl acrylate, 2-bromoethanol, and 3-hydroxypropionitrile to modify chlorosulfonated polyethylene with a chlorine content of 30-40 wt%, a sulfur content of 0.8-2.0%, and a Mooney viscosity (ML(1+4)@100℃) of 45-100. This significantly improves the bonding performance of water-based adhesive compositions containing the modified rubber latex for use between metals and elastomers.

[0091] 3. By constructing a modified rubber latex-nitroso compound-adhesion accelerator system, and especially by controlling the amount of each raw material added in the mother liquor, the present invention enables the provided water-based adhesive composition to exhibit excellent adhesion performance in initial bonding, baking resistance, high-temperature fluid resistance, and corrosive environments, while also maintaining good adhesion performance in high-temperature environments.

[0092] 4. The water-based adhesive composition provided by the present invention, by optimizing the combination of raw materials in the system, has a bonding performance that is basically the same as that of solvent-based adhesives when used for bonding metal substrates and elastomers, while meeting the bonding requirements of various elastomers and having a wider range of applications.

[0093] 5. The water-based adhesive composition provided by the present invention meets VOC requirements, does not contain chlorine-containing solvents such as dichloromethane, trichloromethane, and chlorobenzene, and the adhesive composition itself can be stably stored for more than 6 months, better meeting the needs of practical applications.

[0094] 6. In addition to being used with a primer, the water-based adhesive composition provided by this invention can also be used as a single coating to bond various substrates and elastomers. Its performance is better than commercially available products, and its application scenarios are further broadened. Detailed Implementation

[0095] Examples 1-17

[0096] Examples 1-17 of the present invention provide a modified rubber latex, the formulation of which is shown in Table 1 by mass percentage.

[0097] Table 1

[0098] In Table 1, surfactant A is dodecyl polyethylene glycol sulfate ammonium; the raw materials for preparing modified rubber solution 1-15, by mass percentage, are shown in Table 2. The preparation method of modified rubber solution 1-15 is as follows: halogenated elastomer and solvent are added to a container, stirred at 80℃ for 5 hours, cooled to 75℃, and then modifier is added. The mixture is reacted at a constant temperature for 5 hours to obtain modified rubber solution 1-15.

[0099] Table 2

[0100] In Table 2, “\” indicates that the corresponding raw material addition amount is 0. See Table 3 for the grade of chlorosulfonated polyethylene and related performance parameters.

[0101] Table 3

[0102] The modified rubber emulsion 1-17 is prepared as follows: the modified rubber solution is added to the solution after the surfactant A and water are mixed, and after homogenization and emulsification, the solvent is removed to obtain a modified rubber emulsion with a total solid content of 35wt%.

[0103] The conditions for homogenization emulsification include: a rotation speed of 20,000 rpm, a temperature of 65°C, and a time of 18 min.

[0104] The solvent removal method is vacuum distillation, and the conditions for vacuum distillation include: a pressure of 30 kPa and a temperature of 55°C.

[0105] Application Examples 1-9

[0106] Application Examples 1-9 of the present invention provide an aqueous adhesive composition, the formulation of which is shown in Table 4 by mass percentage.

[0107] Table 4

[0108] In Table 4, “\” indicates that the amount of the corresponding raw material added is 0. The formulas of mother liquor A and B, by mass percentage, are shown in Table 7.

[0109] Application of Comparative Examples 1-12

[0110] Comparative Examples 1-12 of the present invention provide an aqueous adhesive composition, the formulation of which is shown in Table 5 by mass percentage.

[0111] Table 5

[0112] In Table 5, “\” indicates that the amount of the corresponding raw material added is 0. The formula of mother liquor AJ, by mass percentage, is shown in Table 7.

[0113] Application of comparative examples 13-23

[0114] Comparative Examples 13-23 of the present invention provide an aqueous adhesive composition, the formulation of which is shown in Table 6 by mass percentage.

[0115] Table 6

[0116] In Table 6, “\” indicates that the amount of the corresponding raw material added is 0. For the formula of mother liquor A, by mass percentage, see Table 7.

[0117] Table 7

[0118] In Table 7, the preparation method of mother liquor AJ is as follows: In a horizontal grinder, under the grinding parameters of 3000 r / min, add nitrosamines, acid binders, adhesive promoters, carbon black, dispersants, and pure water in the proportions shown in Table 7 and grind until the fineness is <10 μm to obtain mother liquor AJ.

[0119] The raw materials for preparing halogenated natural rubber emulsions in Table 4-6, by weight, include: 120 parts chlorinated natural rubber, 280 parts xylene, 8 parts surfactant B, and 500 parts water.

[0120] The chlorinated natural rubber has a weight-average molecular weight of 100,000–500,000 and a chlorine content of 50–70 wt%, and is classified as follows: S 170 is sourced from Covestro Polymers China Ltd.

[0121] The surfactant B is ammonium dodecylphenol polyoxyethylene ether sulfonate.

[0122] The method for preparing the halogenated natural rubber emulsion is a commonly used emulsion preparation method in the industry.

[0123] The preparation method of the water-based adhesive compositions provided in Application Examples 1-9 and Comparative Examples 1-23 is as follows: The mother liquor, modified rubber latex, halogenated natural rubber latex, and pure water are stirred and mixed to obtain the water-based adhesive composition. The stirring speed is 80 r / min, and the stirring time is 30 min.

[0124] Performance testing

[0125] I. The water-based adhesive compositions provided in Examples 1 and 2 were used to bond metallic iron and NR55 (Taicang Guanlian Rubber) with three elastomers (WDK1, WDK2, and WDK3) specified in the German Rubber Manufacturers Association (WDK). An elastomer composite material was obtained by bonding these materials. The elastomer composite material was subjected to various tests while still hot or cooled to room temperature (25°C). The test results are shown in Table 8. The preparation method of the elastomer composite material is as follows: the iron-based substrate was sandblasted and preheated to 75°C to obtain a pretreated substrate layer; a water-based primer (MEGUM) was sprayed onto the substrate. TM W 9300) forms a primer layer with an average thickness of 10 μm on the surface of the pretreated substrate layer; water-based adhesive compositions 1 and 2 are coated to form a 20 μm water-based adhesive layer on the surface of the primer layer preheated to 75°C; rubber is molded, injected, and injected onto the water-based adhesive layer at 165°C to obtain the elastomer composite material.

[0126] 1. Initial Adhesion: The bonded portion was subjected to peel failure according to ASTM Test D429 - Method B. The elastomer composite was cooled to room temperature, and a peel test was performed at a 45° peel angle. The test was conducted at a speed of 0.8 cm / s at room temperature. After the bond failed, the percentage of rubber retained on the fractured surface was measured.

[0127] 2. Hot Peel Test: The above-mentioned elastomer composite material was immediately peeled off after the bonding reaction was completed (peeling test at a 45° peel angle. Test at a speed of 0.8 cm per second at room temperature). Then, after the bonding failed, the percentage of rubber retained on the bond failure surface was measured.

[0128] 3. Boiling Water Resistance: Drill a small hole on one side of the rubber with a hand drill, then use a rope with a center to pull the elastomer away from the metal. Next, use a razor blade to scratch the adhesive lines at the bonding interface to induce breakage. Then, immerse the elastomer composite material in boiling water at 100°C. After 1 hour, 5 hours, 12 hours, 24 hours, 48 ​​hours, and 72 hours, remove the elastomer composite material from the metal using pliers, and then test the percentage of rubber retained on that portion.

[0129] 4. High Temperature Resistance Test: After cooling the elastomer composite material to room temperature, place it in a 150°C forced-air oven for 15 minutes. Degrade the bonded portion while hot by peeling, according to ASTM Test D429-Method B. Perform the peel test at a 45° peel angle. Test at a speed of 0.8 cm / s at room temperature. After the bond fails, measure the percentage of rubber retained on the damaged surface.

[0130] Table 8

[0131] The data in Table 8 represent the percentage of elastomer failure. A high percentage of elastomer failure is ideal, indicating that the adhesive has stronger bonding performance than the elastomer itself.

[0132] 5. Salt Spray Resistance: The elastomer is NR55. The adhesive portion is polished at the edges using a grinding wheel. Then, the rubber is pulled from the metal with a stainless steel wire to expose the adhesive area and the adhesive line to the environment. The adhesive line is scratched with a razor blade to induce cracking. This portion is then bound to a stainless steel wire and placed in a salt spray chamber. The chamber environment is 100% relative humidity, 95°C, and contains a 5% sodium chloride solution dissolved in the spray liquid, which is distributed throughout the chamber. This portion is placed in this environment for 5 hours, 12 hours, 24 hours, 48 ​​hours, and 72 hours respectively. After removal, the elastomer is peeled from the metal with pliers, and the percentage of residual elastomer on the portion is measured. The test results are shown in Table 9.

[0133] Table 9

[0134] 6. Baking resistance: The elastomer is NR55. The elastomer composite material was exposed to the pre-baking conditions shown in Table 10. The pre-baking was performed before the elastomer came into contact with the coated substrate (this simulates whether the water-based adhesive composition retains sufficient activity to successfully bond the elastomer in actual production). After the elastomer composite material was cooled to room temperature, its bonding performance was evaluated according to the initial adhesion test method. Finally, the percentage of residual elastomer on this part was measured. The test results are shown in Table 10.

[0135] Table 10

[0136] II. The water-based adhesive compositions used in Application Examples 1-9 and Comparative Examples 13-18 were applied to bond metallic iron to NR55, NR70, NBR, SBR, and EPDM (all purchased from Taicang Guanlian Rubber) to obtain elastomeric composite materials. The elastomeric composite materials underwent initial adhesion and boiling water resistance tests, and the test results are shown in Tables 11 and 12, respectively. The preparation method of the elastomeric composite material is as follows: The iron-based substrate was sandblasted and preheated to 75°C to obtain a pretreated substrate layer; a water-based primer (MEGUM) was sprayed onto the substrate. TM W 9300) forms a primer layer with an average thickness of 10 μm on the surface of the pretreated substrate layer; a water-based adhesive composition is applied to form a 20 μm water-based adhesive layer on the surface of the primer layer preheated to 75°C; and rubber is molded, injected, or injected onto the water-based adhesive layer at 165°C to obtain the elastomer composite material.

[0137] Table 11

[0138] Table 12

[0139] III. The water-based adhesive compositions provided in the application examples and comparative examples were used to bond metallic iron and NR55 (Taicang Guanlian Rubber) to obtain an elastomeric composite material. After cooling the elastomeric composite material to room temperature (25°C), a pull-out initial adhesion test was performed (refer to ASTM D429 - Test Method A). The maximum peel value from tensile peeling to breakage and the percentage of rubber breakage were used as the test results (see Table 13). The preparation method of the elastomeric composite material is as follows: a 40mm diameter disc-shaped iron-based substrate was sandblasted and preheated to 75°C to obtain a pretreated substrate layer; a water-based primer (MEGUM) was sprayed onto the substrate. TM W 9300) forms a primer layer with an average thickness of 10 μm on the surface of the pretreated substrate layer; water-based adhesive compositions 1 and 2 are coated to form a 20 μm water-based adhesive layer on the surface of the primer layer preheated to 75°C; rubber is molded, injected, and injected onto the water-based adhesive layer at 165°C to obtain the elastomer composite material.

[0140] Table 13

[0141] IV. Thermal tear resistance: The test specimens with the above-mentioned initial adhesion were placed in a forced-air oven at 150°C and heated for 15 minutes. Then, while still hot, they were stretched and peeled until they broke. The maximum peel force and the percentage of elastomer breakage were recorded. The test results are shown in Table 14.

[0142] Table 14

[0143] V. The water-based adhesive compositions provided in Application Examples 1, 2, 3, 6, 7, 8, and 9, and Comparative Examples 13, 14, and 15, were used to bond the buffer and NR55 (Taicang Guanlian Rubber) to obtain an elastomeric composite material. After cooling the elastomeric composite material to room temperature (25°C), an initial pull-out adhesion test was performed on the buffer (refer to ASTM D429 - Test Method A). The maximum peel value from tensile peeling to breakage and the percentage of rubber breakage were used as the test results (see Table 15). The preparation method of the elastomeric composite material is as follows: the buffer is sandblasted and preheated to 75°C to obtain a pretreated substrate layer; a water-based primer (MEGUM) is sprayed onto the substrate. TM W 9300) forms a primer layer with an average thickness of 10 μm on the surface of the pretreated substrate layer; water-based adhesive compositions 1 and 2 are coated to form a 20 μm water-based adhesive layer on the surface of the primer layer preheated to 75°C; rubber is molded, injected, and injected onto the water-based adhesive layer at 165°C to obtain the elastomer composite material.

[0144] Table 15

[0145] VI. Thermal tear resistance of the buffer: The test specimens with the above-mentioned initial adhesion of the buffer were placed in a forced-air oven at 150°C and heated for 15 minutes. Then, while hot, they were stretched and peeled until they broke. The maximum peel force and the percentage of elastomer breakage were recorded. The test results are shown in Table 16.

[0146] Table 16

[0147] VII. Buffer Resistance to Boiling Water: The test specimen with the initial adhesion of the buffer was placed in a mold and stretched by 30% throughout the test. The stretching was maintained at 30% throughout the test. The test specimen was then placed in a boiling water solution for 250 hours. Subsequently, the test specimen was stretched and peeled until it broke, and the maximum peel value and the percentage of rubber failure were recorded. The test results are shown in Table 17.

[0148] Table 17

[0149] 8. Buffer Resistance to Ethylene Glycol: The test specimen with the initial adhesion of the buffer as described above was placed in a mold and stretched to 30% and maintained at 30% elongation throughout the test. The test specimen was then placed in a 90°C aqueous solution containing 5 wt% ethylene glycol for 250 hours. After the test, the test specimen was removed and cooled to room temperature. Subsequently, the test specimen was stretched and peeled until it broke, and the maximum peel value and the percentage of rubber failure were recorded. The test results are shown in Table 18.

[0150] Table 18

[0151] IX. Single-coat bonding of different substrates: The water-based adhesive compositions provided in Application Examples 1, 2 and Comparative Examples 4-6, as well as commercial water-based adhesives ( 8212) was used to bond metal sheets, zinc sheets, white nylon sheets, black nylon sheets, zinc-plated nickel sheets, 304 stainless steel sheets, and NR55 (Taicang Guanlian Rubber) to obtain an elastomer composite material. The elastomer composite material was cooled to room temperature (25°C) and then subjected to the following tests. The test results are shown in Table 19. The preparation method of the elastomer composite material is as follows: the metal sheets, white nylon, and black nylon substrates were directly used after polishing; the zinc sheets, zinc-plated nickel sheets, and 304 stainless steel sheets were all cleaned using a solvent cleaning method: the bonding surfaces were wiped successively with cotton balls soaked in ethyl acetate and MIBK solution, and then dried at room temperature. The pretreated substrates were preheated to 75°C to obtain pretreated substrates, and then directly coated with a water-based adhesive composition. Examples 1 and 2, Comparative Examples 4-6, and commercial water-based adhesives ( 8212) A 15-20 μm water-based adhesive layer is formed on the surface of a substrate preheated to 75°C. Rubber is then molded, injected, or injected onto the water-based adhesive layer at 165°C to obtain an elastomer composite material.

[0152] Initial adhesion: The bonded portion was debonded according to ASTM Test D429 - Method B. After cooling the elastomer composite to room temperature, a peel test was performed at a 45° peel angle. The test was conducted at a speed of 0.8 cm / s at room temperature. After the bond failed, the percentage of substrate exposure and the percentage of elastomer failure on the bond failure surface were measured. Test results are shown in Table 19.

[0153] Table 19

[0154] The data in Table 19 represent the percentage of substrate exposure and the percentage of elastomer damage. A low percentage of substrate exposure and a high percentage of elastomer damage are ideal.

[0155] 10. Single-coat bonding of different rubbers: Apply the water-based adhesive compositions provided in Examples 1 and 2 and Comparative Examples 4-6, as well as commercial water-based adhesives ( 8212) was used to bond white nylon sheets and NR55 (Taicang Guanlian Rubber) with three elastomers (WDK1, WDK2, WDK3) specified in the German Rubber Manufacturers Association (WDK). The resulting elastomer composite material was tested after cooling the elastomer composite material to room temperature (25°C). The test results are shown in Table 20. The preparation method of the elastomer composite material is as follows: the white nylon sheet is directly used after sanding. The pretreated substrate is preheated to 75°C to obtain a pretreated substrate, and then directly coated with a water-based adhesive composition. Examples 1 and 2 and Comparative Examples 4-6, as well as commercial water-based adhesives (… 8212) A 15-20 μm water-based adhesive layer is formed on the surface of a substrate preheated to 75°C. Rubber is then molded, injected, or injected onto the water-based adhesive layer at 165°C to obtain an elastomer composite material.

[0156] Initial adhesion: The bonded portion was debonded according to ASTM Test D429 - Method B. After cooling the elastomer composite to room temperature, a peel test was performed at a 45° peel angle. The test was conducted at a speed of 0.8 cm / s at room temperature. After the bond failed, the percentage of substrate exposure and the percentage of elastomer failure on the bond failure surface were measured. Test results are shown in Table 20.

[0157] Table 20

[0158] The data in Table 20 represent the percentage of substrate exposure and the percentage of elastomer damage. A low percentage of substrate exposure and a high percentage of elastomer damage are ideal.

Claims

1. A modified rubber latex, characterized in that, The raw materials for its preparation, by mass percentage, include at least: 10-70% modified rubber solution, 0.01-5% surfactant, and water to make up the balance, wherein the modified rubber solution is prepared by modifying halogenated elastomers with modifiers.

2. The modified rubber latex according to claim 1, characterized in that, The raw materials for preparing the modified rubber solution, by mass percentage, include at least the following components: 10-20% halogenated elastomer, 0.5-2% modifier, and solvent to make up the balance.

3. The modified rubber latex according to claim 2, characterized in that, The halogenated elastomer is selected from at least one of halogenated natural rubber and halogen-containing synthetic rubber.

4. The modified rubber latex according to claim 3, characterized in that, The halogen-containing synthetic rubber includes at least one of polychloroprene, halogenated polychloroprene, halogenated polybutadiene, hexachloropentadiene, butadiene-halogenated cyclic conjugated diene adduct, halogenated butadiene-styrene copolymer, halogenated ethylene-propylene copolymer, ethylene-propylene-nonconjugated diene terpolymer, halogenated polyethylene, halogenated sulfonated polyolefin, halogenated poly(2,3-dichloro-1,3-butadiene), copolymer of α-haloacrylonitrile and 2,3-dichloro-1,3-butadiene, and halogenated polyvinyl chloride.

5. The modified rubber latex according to claim 2, characterized in that, The modifier is selected from at least one of the structures shown in formulas (1) to (4). Equation (1): R——OH, where R represents C1~C 40 Straight-chain or branched n-valent alkyl groups, C2-C 30 n-valent straight-chain or branched alkenyl groups, C3-C 30 n-valent straight-chain or branched alkynyl groups, C6-C 40 n-valent aryl group; any -H or -CH3 in R can be replaced by an oxygen atom, a halogen atom, a cyano group, or a methoxy group; Formula (2): Where R1 represents C1~C 40 Straight-chain or branched n-valent alkyl groups, C2-C 30 n-valent straight-chain or branched alkenyl groups, C3-C 30 n-valent straight-chain or branched alkynyl groups, C6-C 40 The n-valent aryl group, R2 represents a methyl or hydrogen atom; any -H in R1 can be replaced by a halogen atom, any -CH3 in R1 can be replaced by a methoxy or cyano group, and any -CH2- in R1 can be replaced by an oxygen atom or a sulfur atom. Equation (3): Equation (4): Where R represents C1~C 40 Straight-chain or branched n-valent alkyl groups, C2-C 30 n-valent straight-chain or branched alkenyl groups, C3-C 30 The n-valent straight-chain or branched alkynyl group and halogen atom; any -H or -CH3 in R can be replaced by an oxygen atom, halogen atom, cyano group, or methoxy group.

6. A water-based adhesive composition, characterized in that, The modified rubber latex containing any one of claims 1-5 comprises, by mass percentage, at least the following components: 4.8-14.4% nitrosamines, 2-10% modified rubber latex, and the balance being pure water.

7. The aqueous adhesive composition according to claim 6, characterized in that, The raw materials for preparing the mother liquor, by mass percentage, shall include at least the following components: 40-60% mother liquor, 2-10% modified rubber latex, 1-5% halogenated natural rubber latex, and the balance being pure water; the raw materials for preparing the mother liquor, by mass percentage, shall include at least 12-24% nitrosamines, 5-15% adhesive accelerators, 8-15% acid binders, 3-18% carbon black, 1-8% dispersants, and the balance being pure water.

8. The aqueous adhesive composition according to claim 6, characterized in that, The acid-binding agent is selected from metal oxides and metal phosphates, wherein the metal oxide is preferably zinc oxide and the metal phosphate is preferably zinc phosphate.

9. The aqueous adhesive composition according to claim 6, characterized in that, The adhesion promoter comprises at least a maleamide compound, which is preferably an aromatic polymaleimide with an aromatic nucleus.

10. The aqueous adhesive composition according to claim 6, characterized in that, The dispersing agent is selected from sodium lignosulfonate, calcium lignosulfonate, basic lignin, and polycarboxylate, preferably sodium lignosulfonate.

Images