Preparation method of single-component water-oil mixed type environment-friendly composite adhesive

Abstract

The application discloses a preparation method of a single-component water-oil mixed environment-friendly composite adhesive, and belongs to the technical field of composite special adhesives. The application combines water and oil in the composite adhesive under the premise that no emulsifier and dispersant is added, by grafting and polymerizing the adhesive with the water-based acrylic ester and monomer polymerization adhesive, so that the excellent characteristics of the oil-based adhesive and the water-based adhesive are organically combined. The composite adhesive has the safety, environmental protection and hygiene performance of the water-based adhesive, and overcomes the defects of the water-based adhesive, such as poor water resistance, slow setting and curing, and the like, and also has the functions of the solvent-based adhesive, such as fast setting, normal-temperature curing, water resistance, washing resistance and excellent initial adhesion effect, and overcomes the safety and environmental protection defects of the current composite adhesive industry.

Description

Technical Field

[0001] This invention belongs to the field of composite adhesive technology, specifically relating to a method for preparing a single-component water-oil mixed environmentally friendly composite adhesive. Background Technology

[0002] Currently, the composite adhesive market is dominated by oil-based (solvent-based) acrylate and rubber-based composite adhesives, accounting for approximately 80% of the composite adhesive market. Oil-based (solvent-based) composite adhesives possess excellent initial tack, water resistance, and flexibility, and evaporate quickly to form a film. However, oil-based (solvent-based) composite adhesives have safety, environmental, and hygiene drawbacks, including flammability during the composite production process, flash points generally below 28°C, difficulty in controlling and eliminating VOCs, and difficulty in eliminating the odor of organic solvents in the finished composite product in a short time. Therefore, the government has proposed a shift from oil-based to water-based adhesives in the composite materials field. Traditional composite adhesives mainly use oil-based (solvent-based) adhesives (generally with a solid content ≤45%). In 2019, the government promulgated the "Standard for Unorganized Emission Control of Volatile Organic Compounds" GB37822-2019, and in 2020, it further stipulated limits for volatile organic compounds in adhesives, promulgating the "Limits for Volatile Organic Compounds in Adhesives" GB33372-2020. The requirement to set VOC content limits for adhesives used in composite materials is a concrete manifestation of the decision to switch from oil-based to water-based adhesives in the industry.

[0003] Water-based acrylic adhesives are low-cost, flame-retardant, and generally have a flash point above 60℃. VOCs are easily controlled and eliminated, resulting in odorless composite products and eliminating safety, environmental, and hygiene concerns. However, during the lamination process, due to surface energy, water-based acrylic adhesives suffer from slow drying speeds and poor initial tack, requiring activation via a lamination evaporation drying tunnel to accelerate film formation, leading to high energy consumption. The presence of emulsifiers also results in poor water resistance and washability of the finished product. Especially after curing, the adhesive film tends to increase hardness and decrease flexibility. Controlling this hardness increase by adding plasticizers often introduces health and hygiene limitations. Adding curing agents requires additional processing steps, and their presence can reduce the flexibility of soft composite products. Therefore, the adoption of water-based adhesives in the low-cost lamination adhesive industry has been difficult.

[0004] This presents a completely new challenge to the field of composite adhesives. The key to successfully transitioning from oil-based to water-based adhesives lies in how to organically combine water-based (hydrophilic) adhesives with oil-based (hydrophobic) adhesives, leveraging the advantages of each phase. Developing a single-component, water-oil hybrid environmentally friendly composite adhesive is of great significance. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to address the shortcomings of existing technologies by providing a method for preparing a single-component water-oil hybrid environmentally friendly composite adhesive. This method solves the compatibility problem between oil-based (solvent-based) and water-based adhesives in single-component water-oil hybrid environmentally friendly composite adhesives, leveraging the advantages of both oil-based and water-based adhesives to meet the requirements of the national standard GB37822-2019 (2020 edition) for the control of fugitive emissions of volatile organic compounds.

[0006] This invention relates to a single-component, oil-water hybrid environmentally friendly composite adhesive, which employs a physical mixing method. The resulting hybrid environmentally friendly composite adhesive incorporates Pickering's emulsion theory and the island theory, representing the innovative approach of this invention. Due to the blending of the aqueous and oil phases, the adhesive primarily exhibits a "sea-island structure," a "sea-sea structure," and a small amount of a "homogeneous system." The aqueous adhesive phase represents the "sea," and the oil phase represents the "islands." During the composite process, the film modulus effect is activated by heat, causing movement within the "three structures." This leads to a reorganization and equilibrium of the hydrophobic and oleophobic properties, accelerating the rapid separation of water during film formation. This results in a certain initial tack strength in the film, allowing the composite material to be properly positioned.

[0007] Based on Pickering's emulsion theory, the different interactions between oil-water two-phase colloidal particles at the water-oil interface significantly influence the dispersion, aggregation, and assembly behavior of these particles at the particle interface, as well as the stability of the Pickering emulsion. Especially during the initial polymerization and granulation of the emulsion, the polar hydrogen bonds and electrical properties of the solvent allow for stable dynamic interactions between the particles in the emulsion capsules. Its advantages include a significant reduction in emulsifier usage. Even with minimal or no emulsifier in the water-oil emulsion, the composite material exhibits reduced or no emulsifier precipitation during application, improving its bonding strength and water resistance; reducing the harm to human health from emulsifier precipitation; and being environmentally friendly. The aqueous adhesive emulsion prepared by this method exhibits strong stability and is less affected by factors such as system pH, salt concentration, temperature, and the composition of the water-oil phase. This invention modifies the flexibility of the water-based adhesive by adding the oil-based adhesive, overcomes the harm to the human body caused by adding plasticizers, and also overcomes the migration and precipitation of plasticizers, further improving the water resistance and weather resistance of the composite material.

[0008] This invention relates to a single-component, water-oil hybrid environmentally friendly composite adhesive. By incorporating an oil-based (hydrophobic) SBS-acrylate monomer graft, the water resistance of the adhesive film is significantly improved. The oil-based adhesive component modifies the originally hydrophobic rubber body through grafting with soft and hard acrylic monomers, maximizing the overcoming of the interfacial incompatibility between the oil-based and water-based adhesives. It also fully utilizes the plasticizing effect of the modified rubber elastomer (oil-based adhesive) in the water-oil adhesive. Simultaneously, the structural composition of the adhesive film formed by the water-oil adhesive results in a certain modulus effect, thereby improving the film's antifreeze properties and enhancing the hand flexibility of the water-based adhesive film.

[0009] This invention prepares a single-component, water-oil hybrid environmentally friendly composite adhesive that combines an oil-based (solvent-based) grafted polymer with a water-based polymer. The preparation method of this invention organically combines the excellent properties of both oil-based and water-based adhesives. This composite adhesive not only possesses the safety, environmental friendliness, and hygiene properties of water-based adhesives but also overcomes many drawbacks of water-based adhesives, such as poor water resistance and slow curing. It also leverages the rapid setting, room-temperature curing, and single-component water resistance of solvent-based adhesives, while overcoming the shortcomings in safety and environmental performance of current composite bonding products.

[0010] This invention relates to an environmentally friendly composite adhesive, applied in a single-component form within the field of composite adhesives. It is suitable for special-function adhesives, primarily used in the interior decoration and maintenance of high-speed trains and aircraft, high-pressure protection of high-pressure pipes in submarines and aircraft carriers, and as a thermal insulation, heat preservation, shock absorption, and protective material. This environmentally friendly composite adhesive possesses characteristics such as high temperature resistance, flame retardancy (cationic rating up to UL94 VO), halogen-free and environmentally friendly, non-toxic, non-dripping, strong adhesion, and strong holding and initial tack. Its advantages are particularly prominent in the production of various bags, shoe materials, sporting goods consumables, automotive and marine equipment accessories, high-speed trains, automotive and new energy electric vehicle decorations, seat and brake pipe manufacturing, electrical protective tapes and soft composite materials, polymer sheets, non-porous materials and sponge composite materials, and composite bonding between fabrics.

[0011] Technical solution: The objective of this invention is achieved through the following technical solution:

[0012] This invention provides a method for preparing a single-component water-oil hybrid environmentally friendly composite adhesive. The composite adhesive is a combination of an oil-based adhesive and a water-based adhesive, compounded without the addition of emulsifiers or dispersants. The oil-based adhesive is an adhesive obtained by graft polymerization of a polymer elastomer with acrylic monomers, functional monomers, and synergists. The water-based adhesive is an adhesive obtained by polymerizing water-based acrylate monomers, functional monomers, organic solvents, and reinforcing agents.

[0013] Preferably, the oil-based adhesive and the water-based adhesive are mixed using a physical mixing method for 180 minutes.

[0014] Preferably, the mass percentage of the oil-based adhesive to the water-based adhesive is 20-50:50-80. To meet the VOC content limits stipulated in the "Standard for the Control of Fugitive Emissions of Volatile Organic Compounds" GB37822-2019 and the "Limits for Volatile Organic Compounds in Adhesives" GB33372-2020 for adhesives used in composite materials, this invention limits the mass percentage of the oil-based adhesive to the water-based adhesive to 20-50:50-80. Simultaneously, by limiting the maximum amount of the oil-based adhesive, the environmental friendliness of the composite adhesive of this invention is highlighted.

[0015] The single-component oil-water hybrid environmentally friendly composite adhesive prepared in this invention is ultimately used to bond porous sheets, SBR, sea glass, Ossone, sponge, nonwoven fabric, and cloth base. To prevent excessive penetration of the adhesive into the composite substrate during the lamination (production line) process, which could affect the quality and density of the composite material, effective design and control of the mixing ratio and viscosity of the oil-based and water-based adhesive components before compounding are essential.

[0016] The acrylic monomers and functional monomers described in this invention are important raw materials for improving the cohesive strength of oil-based (solvent-based) modified thermoplastic elastomers, specifically designed for the materials being bonded. The formulation design not only needs to consider the above requirements but also requires determining the polarity of the monomers using the principle of "like dissolves like." This means considering the materials being bonded. Furthermore, it requires considering the compatibility between the oil-based (solvent-based) and water-based adhesives, as well as the mutual repulsion between the two phases and the need for a two-phase system. In this invention, the oil-based and water-based adhesives are physically compounded, eliminating the need for emulsifiers and dispersants. Excessive use of emulsifiers and dispersants can easily lead to a decrease in water resistance, especially the washability of the bonded parts.

[0017] Preferably, the components participating in graft polymerization in the oily portion of the adhesive include a polymeric elastomer, an acrylic monomer, a functional monomer, and a tackifying resin; the polymeric elastomer is an SBS thermoplastic elastomer; the SBS thermoplastic elastomer is selected from one or both of linear and star-shaped structures; the functional monomer contains at least one carboxyl functional monomer; and the tackifying resin includes a phenolic resin. The phenolic resin not only functions as a tackifying resin but also participates in the graft polymerization reaction.

[0018] Furthermore, the SBS thermoplastic elastomer is selected from two types: linear structure and star structure, and the star structure thermoplastic elastomer accounts for less than 2% of the total SBS thermoplastic elastomer mass.

[0019] Furthermore, the SBS thermoplastic elastomer is selected from two types: linear structure and star structure, with the linear structure thermoplastic elastomer accounting for more than 98% of the total SBS thermoplastic elastomer mass.

[0020] The graft polymerization of SBS thermoplastic elastomer with acrylic monomers and functional monomers contributes to the "island" structure of the semi-oil, semi-water adhesive. The produced island chains function as much as possible as a "continental shelf." The film formation states of water-based (emulsion) adhesives and oil-based (solvent-based) composite adhesives differ. In water-based adhesives, water evaporation and capillary action cause polymer microspheres to approach each other, deforming and fusing under capillary pressure to form a continuous film. This allows molecules to recombine and aggregate, generating sufficient macromolecular cohesive force within the film. In contrast, oil-based (solvent-based) adhesives rely on solvent evaporation, chain growth, and molecular entanglement to generate sufficient macromolecular cohesive force. Based on the three principles of adhesion—"interlocking," adsorption, and chemical bonding"—the bonding effect is most ideal when all these effects occur simultaneously during adhesion. "Interlocking" bonding is the simplest. Therefore, when considering interlocking bonding, the surface tension of the adhesive should be minimized. Since water-based adhesives exist in capsule form, they possess a certain surface tension. Therefore, in the preparation of water-oil adhesives, the lower surface tension and permeability of oil-based (solvent-based) adhesives should be utilized to allow the colloid to penetrate and interlock within the adhesive materials, achieving an anchoring effect. Thus, the selection of linear SBS thermoplastic elastomers for the graft polymerization reaction should be prioritized, but the higher cohesive strength of star-shaped elastomers compared to linear ones should not be overlooked. Star-shaped thermoplastic elastomers can be used as a viscosity modifier for oil-based adhesives.

[0021] In order for oil-water two-phase adhesives to have good affinity, the selection of monomers needs to take into full account hydrophilic monomers, such as polar monomers containing carboxyl groups.

[0022] The tackifying resin described in this invention is an indispensable component for improving the initial tack of single-component water-oil hybrid environmentally friendly composite adhesives, and is an essential raw material for achieving the initial tack effect of water-oil adhesives. While there are numerous reports on how to apply tackifying resins to water-oil hybrid environmentally friendly composite adhesives to improve initial tack, effectively overcoming the "floating oil" phenomenon of tackifying resin precipitation in water-oil adhesives without the need for emulsifiers or dispersants is a crucial aspect of this invention. The tackifying resin of this invention is prepared by embedding the tackifying resin into an oil-based graft polymer using IPN technology in the preparation of the oil-based adhesive. This not only completely solves the "floating oil" phenomenon of tackifying resin precipitation but also improves the overall water resistance of the water-oil hybrid environmentally friendly composite adhesive without the use of emulsifiers or dispersants. Furthermore, incorporating hydroxyl-value phenolic resin into the graft polymerization reaction of the oil-based adhesive accelerates the reaction process between the thermoplastic elastomer and the monomer.

[0023] Preferably, the water-based adhesive is produced by emulsifying and polymerizing vinyl acetate and acrylic monomers, with an organic solvent added to the base material, and the solids content of the water-based adhesive is greater than 50%.

[0024] Furthermore, the organic solvent is selected from toluene, butanone, xylene, or methyl isobutyl ketone.

[0025] Preferably, the organic solvent used in the preparation of the oily adhesive is selected from any one or more of cyclohexane, toluene, ethyl acetate, dimethyl carbonate, butanone, methanol, xylene, methyl isobutyl ketone, methyl isopropyl ketone, solvent oil, methyl acetate, butyl acetate, tetrachloroethylene, or methanol.

[0026] The selection of the aforementioned organic solvents should not only facilitate the graft polymerization reaction of the oil-based portion of the single-component oil-water mixed environmentally friendly composite adhesive, but also comprehensively consider the affinity between the oil-based and water-based adhesive components. The solubility parameters of the solvent system for the oil-based adhesive component and the level of hydrogen bonds in the solvent play a significant role in the formulation of water-oil mixed environmentally friendly composite adhesives.

[0027] More preferably, the synergist is any one or more of dicyclopentene ethoxylate methacrylate, trifluoroethyl methacrylate, hydroxyl silicone oil, silane coupling agent A-151, KH-550, KH-560, KH-570, Tween 80, or OP-10.

[0028] Flame retardants can also be added during the preparation of the composite adhesive of this invention. The flame retardant can be configured according to the needs of the application field. Currently used flame retardants are generally nitrogen-based and phosphorus-based, all of which are organic compounds. Most flame retardants have poor affinity with water-based adhesives, and because the curing morphology of the adhesive film (adhesive layer) of water-based adhesives differs from that of oil-based adhesives, most flame retardants added to water-based adhesives adhere to the surface layer of the adhesive. The product of this invention is a semi-oil, semi-water system. Due to the introduction of oil-based (solvent-based) adhesives, the selection of flame retardant varieties is greatly expanded. Oil-based adhesives, especially those with elastomer-grafted polymers, utilize IPN technology to provide an acceptor for the flame retardant, allowing it to firmly adhere to the adhesive film. This solves the drawback of water-based flame-retardant adhesives being susceptible to washing (washing).

[0029] Preferably, the preparation of the oily adhesive includes the following steps: heating and dissolving the polymer elastomer in an organic solvent, adding a tackifying resin, continuing to heat and adding acrylic monomers and functional monomers to carry out a grafting reaction, with a stirring speed of 8-10 r / min, and the viscosity reaching 2000-2200 mp / 95℃, adding a terminator while cooling, adding the tackifying resin again, controlling the viscosity to 5000-7500 mp, adding an environmentally friendly synergist, adjusting the viscosity with a diluent, and feeding the material after cooling to below 35℃.

[0030] Preferably, the preparation of the aqueous adhesive includes the following steps:

[0031] (1) Monomer pre-emulsification: Water, emulsifier and protective colloid are dispersed. After dispersion, acrylic monomer is added and dispersion is continued for 30-50 minutes to obtain a pre-emulsified emulsion for later use. The pH value of the aqueous medium is controlled at 4.5-5.5.

[0032] (2) Polymerization of seed emulsion: Disperse water, emulsifier, organic solvent and buffer, heat and raise temperature, add initiator, 8% of the total mass of the emulsion pre-emulsified in step (1) as emulsion seed, and pre-polymerize;

[0033] (3) Polymerization of emulsion: After the blue light phenomenon is observed in the reaction system, the remaining emulsion and initiator are added at the same time. The emulsion dropping time is controlled at 240 min, the initiator dropping time is controlled at 270 min, and the temperature is controlled at 80℃~85℃.

[0034] (4) Emulsion formation: After the emulsion and initiator are added, continue to keep warm, and then cool down after the warming is completed;

[0035] (5) Emulsion conditioning: When the temperature drops to 70°C, the residual monomers are post-treated;

[0036] (6) Emulsion reinforcement: When the temperature drops to 45℃, add a reinforcing agent for maturation;

[0037] The stirring speed in the above steps is 100-160 r / min.

[0038] In a preferred embodiment of the present invention, in step (5) emulsion adjustment, when the temperature drops to 70°C, add sodium iodide + water and tert-butyl hydrogen peroxide + water. After adding, keep warm, and after the warming is completed, cool down and post-process the residual monomer.

[0039] This invention relates to an aqueous adhesive fraction prepared by emulsifying vinyl acetate and acrylic monomers, with the substrate undergoing emulsification polymerization in the presence of an organic solvent. This differs fundamentally from the preparation of conventional water-based emulsion adhesives. The purpose of this invention is to provide a desired aqueous adhesive for physical compounding with an oil-based adhesive fraction without adding emulsifiers or dispersants. Introducing an organic solvent into the polymerization reaction of the aqueous adhesive has the advantage of effectively reducing backflow caused by the precipitation (separation) of emulsion monomers at high reaction temperatures during the "temperature surge" phenomenon, thus maximizing the stability of the emulsion particles during polymerization. Furthermore, the aqueous emulsion adhesive particles produced by the organic solvent-introduced polymerization reaction are colloidal particles formed after the emulsion particles have swelled under the influence of the organic solvent. The presence of organic solvents in similar compatibility systems provides better electro-affinity during later physical compounding, while reducing the dramatic increase in viscosity of compounded adhesives caused by the swelling effect of the oil-based adhesive solvent on the water-based adhesive during water-oil adhesive compounding.

[0040] Furthermore, the particle size of the seed emulsion is controlled to be <100nm, and the glass transition temperature Tg is -4 to 1℃; the emulsifier adopts an anionic surfactant and nonionic surfactant system, and the total amount of the anionic surfactant and nonionic surfactant is controlled between 4% and 6%.

[0041] This invention employs anionic and nonionic emulsifier systems. When the emulsifier's ionic characteristics are anionic, with a relatively long EO chain segment, and it also possesses nonionic properties, with an active ingredient content approaching 33%, it is particularly suitable for the homopolymerization and copolymerization of acrylates, vinyl acetate, and styrene-acrylic emulsions. The type and concentration of the emulsifier directly affect the initiation rate and chain growth rate. When selecting a suitable emulsifier, its hydrophilic-lipophilic balance (HLB) value should be considered first, followed by the affinity between the monomer and the emulsifier. Generally, the more similar the molecular structures, the better the affinity. When the HLB value of the mixed emulsion is low, the chain growth rate during emulsion polymerization is fast, the particle size is large, the emulsion polymerization conversion rate is low, and it is prone to aggregation or even demulsification. Conversely, when the HLB value of the mixed emulsifier is high, the chain growth rate during emulsion polymerization is slow, the particle size is small, and the emulsion polymerization conversion rate is also low. Experiments have shown that the HLB value of emulsifiers used in O / W (oil-in-water) emulsions is typically between 8 and 18; while that used in W / O (water-in-oil) emulsions is typically between 3 and 6. In emulsion preparation, besides selecting the emulsifier based on the desired emulsion type, the properties of the oil phase also influence the required HLB value. When the hydrophilic-lipophilic balance (HLB value) is established between 7 and 9, it exhibits good emulsifying effects. In particular, the side chains of the dispersing emulsifier contain both hydrophilic ethylene oxide chains and lipophilic fatty chains, which act as solubilizers with the intervention of nonionic and anionic surfactants, and also demonstrate good affinity for oily adhesive formulations.

[0042] This invention prepares a one-component, water-oil hybrid environmentally friendly composite adhesive by compounding an aqueous adhesive with an SBS-acrylate monomer grafted modifier (oil-based adhesive). The oil-based and aqueous adhesives are physically compounded without the addition of emulsifiers or dispersants, resulting in a composite adhesive that still exhibits good adhesive properties. This invention solves the problem of requiring large-scale evaporation and drying tunnels for traditional water-based composite adhesives, addresses the issue of poor initial tack, and avoids the safety risks associated with VOC treatment of oil-based (solvent-based) adhesives, thereby achieving a more efficient, safe, and environmentally friendly product.

[0043] To fully utilize the superior initial tack, excellent flexural strength, crack resistance, and temperature and fatigue resistance of oil-based adhesives, they are incorporated into the production process of water-oil hybrid composites. Oil-based grafted polymers are integrated into the water-based adhesive to act as bulk plasticizers, resulting in synergistic evaporation of water and oil, which rapidly increases the initial tack of the composite material. The film-forming body participates in plasticization in a solid plasticizing form, overcoming the migration effect of externally added plasticizers. This allows for the reduction or elimination of external plasticizers during adhesive production, improving the industry's hygiene and quality requirements. Simultaneously, it overcomes the problem of decreased hand feel after repeated washing of composite materials and solves issues such as poor wetting, poor interfacial diffusion, and orange peel texture when bonding low surface energy materials with pure water-based adhesives.

[0044] The single-component oil-water hybrid environmentally friendly composite adhesive prepared by this invention is a single-component product that does not require a curing agent and can achieve self-crosslinking at room temperature. It is a safe and environmentally friendly adhesive, significantly reducing VOC emissions. The composite product overcomes the problem of solvent residue. It complies with the national standards GB37822-2019, GB33372-2020, and GB19340-2014, which are about to be fully implemented as mandatory standards. Its water resistance, heat resistance, and water washability fully meet the quality requirements for composite materials. In the process of "oil-to-water" conversion in adhesive applications, it is applicable to the current solvent-based mechanical equipment composite processes in the composite materials industry, realizing a transformation in the application adhesive system without changing the application equipment. Its initial tack is comparable to solvent-based composite adhesives (the initial tack of solvent-based adhesives in the industry can meet the requirements of soft composite products, generally with an initial tack of 3 N / cm), overcoming the cumbersome volatilization, setting, and positioning processes of pure water-based adhesives.

[0045] Beneficial effects:

[0046] (1) This invention organically combines water and oil in a composite adhesive by grafting acrylic monomers onto a polymeric elastomer and water-based acrylate and monomeric polymeric adhesives without the addition of emulsifiers or dispersants. This has significant practical implications for the application of composite adhesives. From the perspective of research on water-oil composite adhesives, this invention breaks the traditional reliance on emulsifiers to achieve the organic combination of incompatible water and oil phases.

[0047] (2) The composite adhesive of the present invention integrates the water resistance, washability, rapid film formation and excellent initial tack of oil-based adhesives with the environmental protection, safety, hygiene and low cost of water-based adhesives, thus solving the long-standing problem of long process open bonding and positioning time that restricts the drying of water-based composite adhesives.

[0048] (3) In the composite application process, this invention achieves the effects of composite bonding and shaping without adding evaporation drying tunnels, changing existing solvent-based adhesive machinery (and production lines), or altering the open process time. This invention meets the safety and environmental protection requirements of the composite adhesive industry, reduces the energy consumption of the production line composite process, effectively reduces the pollution caused by organic solvent adhesives to the environment, and eliminates the odor remaining in the finished composite material. It is a concrete manifestation of the decision to switch from oil to water in the adhesive industry. Detailed Implementation

[0049] In this embodiment of the invention, the water-based adhesive is exemplified by an acrylic emulsion as a water-oil compound.

[0050] The formulation of the water-based adhesive is shown in Table 1. The amount of material added is by weight.

[0051] The formulation of the oil-based adhesive is shown in Table 2. The amount of material added is expressed in parts by weight.

[0052] Table 1 Formulations of water-based partial adhesives

[0053]

[0054] Continued from Table 1

[0055]

[0056] Table 2 Formulations of Oil-Based Adhesives

[0057]

[0058] Note: If using a blade coater, a synergist (dispersant / emulsifier) ​​may be added; if using a roller coater, a small amount may be added or none may be added.

[0059] The technical solution of the present invention will be described in detail below through specific embodiments, but the scope of protection of the present invention is not limited to the embodiments described.

[0060] Example 1: A method for preparing the water-based portion of a single-component water-oil mixed environmentally friendly composite adhesive, comprising the following steps: (This example uses Formulation 1 from Table 1)

[0061] (1) Monomer pre-emulsification: 622 parts of deionized water were injected into the reactor, stirring was started and 88 parts of emulsifier LA300 / SB, 25 parts of protective colloid (polyvinyl alcohol PVA1788 solution mass fraction 13.56%) and 40 parts of acrylamide were added for dispersion (dispersion time controlled at 120 minutes). After dispersion, acrylic monomers (methyl methacrylate MMA 11 parts, acrylic acid AA 100 parts, vinyl acetate 1103 parts, butyl acrylate 987 parts), 75 parts of styrene, and 10 parts of functional monomer methacrylic acid were added and dispersion was continued for 30-50 minutes.

[0062] (2) Polymerization of seed emulsion: 634 parts of deionized water were injected into the reactor, stirring was started and a certain amount of 132 parts of emulsifier LA300 / SB and buffer (14 parts of baking soda) were added and dispersed for 30 minutes. Heating was started and stopped when the temperature reached 65°C. When the temperature in the reactor reached 68°C, 8% of the total amount of the pre-emulsified emulsion in step (1) was added as emulsion seed and 24.4 parts of initiator B (13.9% APS aqueous solution by mass) for pre-polymerization.

[0063] (3) Polymerization of emulsion: After the temperature in the reactor naturally rises to 78°C and blue light appears in the reactor, the remaining emulsion and 138.7 parts of initiator C (mass fraction 1.23% APS aqueous solution) are added dropwise simultaneously. The emulsion addition time is controlled at 240 min, the initiator C addition time in the catalyst tank is controlled at 270 min, and the temperature is controlled at 80°C to 85°C during the addition process.

[0064] (4) Emulsion formation: After the emulsion is added, keep warm for 30 minutes. After the initiator is added, keep warm for another 60 minutes. After the warming is completed, cool down.

[0065] (5) Emulsion adjustment: When the temperature drops to 70℃, add the following ingredients in two stages: 1.5 parts of chloroform + 8 parts of deionized water, 17.5 parts of tert-butyl hydroperoxide + 8 parts of deionized water. The addition time is controlled at 30 min. After the addition is completed, keep the temperature for 20 min. After the temperature is completed, cool down.

[0066] (6) Emulsion reinforcement: When the temperature drops to 45℃, add 10 parts of resin mixture (hydrogenated rosin and toluene dissolved in a 1:1 ratio) for curing. The curing time is controlled at 90 min. The water-based component of the single-component water-oil mixed environmentally friendly composite adhesive is thus prepared.

[0067] The stirring speed in the above steps is 100-160 r / min.

[0068] Experimental results: After adding toluene to the base mixture, it was not easy for the mixture to separate into layers, and the emulsion polymerization reaction rate was stable.

[0069] Example 2: Following the preparation method of Example 1, using Formulation 2 in Table 1, a water-based component of a single-component water-oil mixed environmentally friendly composite adhesive was prepared. In this example, the acrylic monomers (85 parts methyl methacrylate (MMA), 106 parts AA acrylate, 1268 parts vinyl acetate, and 797 parts butyl acrylate), 42.5 parts acrylamide, and 100 parts methyl isobutyl ketone (Methyl isobutyl ketone) were used as the organic solvent.

[0070] Experimental results: After adding methyl isobutyl ketone to the base mixture, it was not easy for the mixture to separate into layers, and the emulsion polymerization reaction was stable, but the finished product had a strong odor.

[0071] Example 3: Following the preparation method of Example 1, using Formulation 6 in Table 1, a water-based component of a single-component water-oil mixed environmentally friendly composite adhesive was prepared. In this example, the acrylic monomers (methyl methacrylate (MMA) 15 parts, AA acrylate 105 parts, vinyl acetate 1083 parts, butyl acrylate 974 parts, isooctyl acrylate 63 parts, acrylonitrile 55 parts), acrylamide 40 parts, and xylene 100 parts as the organic solvent were used.

[0072] Experimental results: After adding xylene to the base mixture, it was not easy for the layers to separate; the emulsion polymerization reaction rate was stable; and the prepared water-based adhesive was not easy to dry (threading) after bonding.

[0073] Example 4: A method for preparing the water-based portion of a single-component water-oil mixed environmentally friendly composite adhesive, comprising the following steps: (This example uses formulation 7 from Table 1)

[0074] (1) Monomer pre-emulsification: 622 parts of deionized water were injected into the reactor, stirring was started and 88 parts of emulsifier LA300 / SB, 25 parts of protective colloid (13.56% polyvinyl alcohol PVA1788 solution by mass fraction) and 40 parts of acrylamide were added and dispersed (dispersion time was controlled at 120 min). After dispersion, acrylic monomers (11 parts of methyl methacrylate MMA, 100 parts of acrylic acid AA, 1103 parts of vinyl acetate, 987 parts of butyl acrylate), 75 parts of styrene and 10 parts of functional monomer methacrylic acid were added and dispersed for 30-50 min before use.

[0075] (2) Polymerization of seed emulsion: 634 parts of deionized water were injected into the reactor, stirring was started and a certain amount of emulsifier LA300 / SB 132 parts, organic solvent toluene 120 parts, and buffer (baking soda 14 parts) were added. After dispersing for 30 minutes, heating was started and stopped when the temperature reached 65°C. When the temperature in the reactor reached 68°C, 8% of the total amount of the pre-emulsified emulsion in step (1) was added as emulsion seed and 24.4 parts of initiator B (mass fraction 13.9% APS aqueous solution) were added for pre-polymerization.

[0076] (3) Polymerization of emulsion: After the temperature in the reactor naturally rises to 78°C and blue light appears in the reactor, the remaining emulsion and 138.7 parts of initiator C (1.23% APS aqueous solution by mass) are added dropwise simultaneously. The emulsion is added for 240 min, the initiator C is added for 270 min, and the temperature is controlled at 80°C to 85°C during the addition process.

[0077] (4) Emulsion formation: After the emulsion is added, keep warm for 30 minutes. After the initiator is added, keep warm for another 60 minutes. After the warming is completed, cool down.

[0078] (5) Emulsion adjustment: When the temperature drops to 70℃, add the following ingredients in two stages (1.5 parts of chlorophyll block + 8 parts of deionized water, 17.5 parts of tert-butyl hydroperoxide + 8 parts of deionized water). The addition time is controlled at 30 min. After the addition is completed, keep the temperature for 20 min. After the temperature is completed, cool down.

[0079] (6) Emulsion reinforcement: When the temperature drops to 45℃, add 15 parts of resin mixture (hydrogenated rosin and toluene dissolved in a 1:1 ratio) for curing. The curing time is controlled at 90 min. The water-based component of the single-component water-oil mixed environmentally friendly composite adhesive is thus prepared.

[0080] Experimental results: The amount of toluene added as a base layer was increased, and the mixture was less prone to separation, resulting in a stable emulsion polymerization rate.

[0081] Example 5: Following the preparation method of Example 1, using Formulation 8 in Table 1, a water-based component of a single-component water-oil mixed environmentally friendly composite adhesive was prepared. In this example, the acrylic monomers (11 parts methyl methacrylate (MMA), 75 parts AA acrylate, 953 parts vinyl acetate, 100 parts methyl acrylate, 884 parts butyl acrylate, and 253 parts isooctyl acrylate), 40 parts acrylamide, and 120 parts methyl isobutyl ketone (Methyl isobutyl ketone) were used as the organic solvent.

[0082] Experimental results: Adding more methyl isobutyl ketone to the base layer increased the amount of methyl isobutyl ketone used, making it less prone to separation after mixing, but the finished product had an excessively strong odor.

[0083] Example 6: Following the preparation method of Example 1, using formulation 12 in Table 1, a water-based component of a single-component water-oil mixed environmentally friendly composite adhesive was prepared. In this example, the acrylic monomers (methyl methacrylate (MMA) 15 parts, acrylate (AA) 116 parts, vinyl acetate 1030 parts, butyl acrylate 1070 parts, isooctyl ester 43 parts), acrylamide 40 parts, and xylene 120 parts as the organic solvent were used.

[0084] Experimental results: Adding xylene to the base coat increased the amount of xylene, making it less prone to separation after mixing. The reaction rate was stable, but there was no obvious effect. The prepared water-based adhesive was not easy to dry (threading) after bonding.

[0085] Comparative Example 1: Preparation of the original water-based adhesive

[0086] In water-based adhesives, those without the addition of organic solvents are called original water-based adhesives. The preparation method of Example 4 is used here, except that no organic solvent is added.

[0087] Comparative Example 2: Following the preparation method of Example 1, a water-based component of a single-component water-oil mixed environmentally friendly composite adhesive was prepared using formulation 3 in Table 1. In this example, the acrylic monomers (methyl methacrylate (MMA) 50 parts, AA acrylate 106 parts, vinyl acetate 620 parts, butyl acrylate 684 parts, methyl acrylate 200 parts), acrylamide 40 parts, styrene 600 parts, and ethyl acetate 100 parts were used as the organic solvent.

[0088] Experimental results: After adding ethyl acetate to the base mixture, it was slightly soluble and easily separated into layers.

[0089] Comparative Example 3: Following the preparation method of Example 1, a water-based component of a single-component water-oil mixed environmentally friendly composite adhesive was prepared using formulation 4 in Table 1. In this example, the acrylic monomers (AA acrylate 126 parts, vinyl acetate 1258 parts, butyl acrylate 800 parts, ethyl acrylate 86 parts), acrylamide 40 parts, and methanol 100 parts were used as the organic solvent.

[0090] Experimental results: After adding methanol to the base mixture, it was not easy to separate into layers. The emulsion polymerization reaction was too fast, and clumping and residue were prone to occur during the reaction. The emulsion adhesive had no flowability.

[0091] Comparative Example 4: Following the preparation method of Example 1, using Formulation 5 in Table 1, a water-based component of a single-component water-oil mixed environmentally friendly composite adhesive was prepared. In this example, the acrylic monomers (methyl methacrylate (MMA) 15 parts, AA acrylate 105 parts, vinyl acetate 1123 parts, butyl acrylate 984 parts, isooctyl ester 63 parts), acrylamide 40 parts, and cyclohexane 100 parts were used as the organic solvent.

[0092] Experimental results: After adding cyclohexane to the base mixture, the mixture became immiscible and separated into layers.

[0093] Comparative Example 5: Following the preparation method of Example 1, using Formulation 9 in Table 1, a water-based component of a single-component water-oil mixed environmentally friendly composite adhesive was prepared. In this example, the acrylic monomers (methyl methacrylate (MMA) 20 parts, AA acrylate 105 parts, methyl acrylate 50 parts, vinyl acetate 1003 parts, butyl acrylate 984 parts, isooctyl acrylate 78 parts), acrylamide 40 parts, and ethyl acetate 120 parts as the organic solvent.

[0094] Experimental results: After adding ethyl acetate to the base mixture, it was slightly soluble and easily separated into layers.

[0095] Comparative Example 6: Following the preparation method of Example 1, using formulation 10 in Table 1, a water-based component of a single-component water-oil mixed environmentally friendly composite adhesive was prepared. In this example, the acrylic monomers (methyl methacrylate (MMA) 15 parts, acrylate (AA) 116 parts, vinyl acetate 1096 parts, butyl acrylate 984 parts, isooctyl ester 70 parts), acrylamide 40 parts, and methanol 120 parts as the organic solvent.

[0096] Experimental results: After adding methanol to the base mixture, it was not easy for the mixture to separate into layers. The emulsion polymerization reaction was too fast, and clumping and residue were prone to occur during the reaction. The emulsion adhesive had no flowability.

[0097] Comparative Example 7: Following the preparation method of Example 1, using formulation 11 in Table 1, a water-based component of a single-component water-oil mixed environmentally friendly composite adhesive was prepared. In this example, the acrylic monomers (methyl methacrylate MMA 32 parts, AA acrylate 116 parts, vinyl acetate 1096 parts, butyl acrylate 984 parts, isooctyl ester 53 parts), acrylamide 40 parts, and cyclohexane 120 parts were used as the organic solvent.

[0098] Experimental results: After adding cyclohexane to the base mixture, the mixture became immiscible and separated into layers.

[0099] Peel strength tests (referring to GB2792-2014 Test Method for Peel Strength of Adhesive Tapes) and water resistance tests (referring to FZ / T80007.2-2006 "Test Method for Wash Resistance of Adhesive Interlining Garments") were conducted on the water-based adhesives prepared in Examples 1-6 of this invention and the original water-based adhesive prepared in Comparative Example 1. The results are shown in Table 3.

[0100] Table 3 Test Results of Water-based Partial Adhesives and Raw Water-based Adhesives

[0101]

[0102] As can be seen from the table above:

[0103] (1) The bonding strength of the water-based partial adhesive prepared in Example 1 is significantly higher than that of the original water-based adhesive, while the water-washing resistance is also extremely obvious. The substrate damage is about 96%.

[0104] (2) The bonding strength of the water-based partial adhesive prepared in Example 2 is significantly improved compared to the bonding strength of the original water-based adhesive, while its water resistance is also extremely obvious. The substrate damage is approximately 98%.

[0105] (3) The water-based partial adhesive prepared in Example 3 had no significant effect on the bonding strength.

[0106] (4) The bonding strength of the water-based partial adhesive prepared in Example 4 is significantly improved compared to that in Example 1, while its water resistance is also extremely obvious. The substrate is damaged by about 100%.

[0107] (5) The bonding strength of the water-based partial adhesive prepared in Example 5 is significantly improved compared to that in Example 2, while the water-washing resistance is extremely obvious. The substrate damage is about 100%.

[0108] (6) The water-based adhesive prepared in Example 6 showed no significant effect on bonding strength. Initial tack was poor if the production line lacked an evaporation drying tunnel.

[0109] The above experiments show that the results of preparing water-based adhesives by participating in emulsion polymerization reactions are different, whether organic solvents are not added or different solvents are added.

[0110] Storage stability tests were conducted on the aqueous adhesives prepared in Examples 1-6 of this invention (referring to General Rules for Storage of Commonly Used Hazardous Chemicals BG15603-1995), and the results are shown in Table 4:

[0111] Table 4. Storage stability results of water-based adhesives

[0112]

[0113] The experiments show that the water-based partial adhesives prepared in Examples 1-6 all have excellent storage stability.

[0114] In summary, considering the bonding strength and water resistance of the finished product, the water-based adhesive prepared in Example 4 exhibits the best quality. Therefore, Formulation 7 is the preferred choice.

[0115] This invention discloses a single-component water-oil mixed environmentally friendly composite adhesive, in which the solvent composition of the oil-based adhesive plays a crucial role in the graft polymerization process. In water-oil compounding, the use of emulsifiers and dispersants in the preparation of the oil-based adhesive imposes certain requirements and limitations on the solvent composition. Example 7 describes a method for preparing the oil-based portion of a single-component water-oil mixed environmentally friendly composite adhesive, comprising the following steps: (using Formulation 1 from Table 2)

[0116] In a 1000mL three-necked flask equipped with a stirrer and condenser, add 527 parts toluene and 50 parts xylene according to Formula 1. Start stirring, add 303 parts linear SBS and 5 parts star-shaped SBS, heat to 40℃, and stir for 1 hour. After the SBS dissolves, the temperature reaches 50-55℃. Add 2 parts phenolic resin 2402, stir for 0.3 hours, raise the temperature to 60℃, and slowly add acrylic monomers (68 parts MMA and AA, 14 parts butyl acrylate BA) and 5 parts functional monomer (maleic anhydride). Stir for 0.2 hours, and simultaneously raise the temperature to 80℃. Begin dropping the initiator benzoyl peroxide (BPO). 1.1 parts were added dropwise, and the reaction was carried out for 1 hour. After the addition was complete, the stirring speed was controlled at 10 rpm, and the temperature was controlled at 85-98℃. The grafting reaction was continued for 2 hours until the viscosity reached 2000-2200 mp / 80℃. Then, 1.9 parts of terminator 1010 (antioxidant) and 60 parts of toluene were added, and the mixture was cooled simultaneously. The stirring speed was 55-60 rpm. Then, 19 parts of SBS star-shaped resin, 260 parts of tackifying resin (C9, 37 parts of terpene resin T-100, and 41 parts of hydrogenated rosin) were added and the mixture was stirred for 1.5 hours until the viscosity was controlled at 5000-7500 mp. Finally, 0.05 parts of synergist Tween 800 were added. The viscosity was adjusted with 95 parts of toluene as a diluent. The mixture was fed after cooling to below 35℃. The solid content was >50%.

[0117] Example 8: Following the preparation method of Example 7, using Formula 2 in Table 2, an oil-based component of a single-component water-oil mixed environmentally friendly composite adhesive was prepared. In this example, the diluent was 95 parts xylene.

[0118] Example 9: Following the preparation method of Example 7, using Formulation 3 in Table 2, an oil-based component of a single-component water-oil mixed environmentally friendly composite adhesive was prepared. In this example, the diluent was 95 parts of methyl isobutyl ketone.

[0119] Example 10: Following the preparation method of Example 7, using formulation 4 in Table 2, an oil-based component of a single-component water-oil mixed environmentally friendly composite adhesive was prepared. In this example, the diluent was 95 parts of ethyl acetate.

[0120] Example 11: Following the preparation method of Example 7, using formulation 5 in Table 2, an oil-based component of a single-component water-oil mixed environmentally friendly composite adhesive was prepared. In this example, the diluent was 95 parts methanol.

[0121] Example 12: Following the preparation method of Example 7, using formulation 6 in Table 2, an oil-based component of a single-component water-oil mixed environmentally friendly composite adhesive was prepared. In this example, the diluent was 25 parts toluene and 70 parts methyl isobutyl ketone.

[0122] Example 13: Following the preparation method of Example 7, using formulation 7 in Table 2, an oil-based component of a single-component water-oil mixed environmentally friendly composite adhesive was prepared. In this example, the diluent was 95 parts of cyclohexane.

[0123] To clearly explain the preparation method, effects, and product quality of a single-component water-oil mixed environmentally friendly composite adhesive, it is necessary to involve the water-based adhesive (in this embodiment, only vinyl acetate-acrylic emulsion is used as an example) in order to comprehensively judge the quality of the oil-based adhesive in a single-component water-oil mixed environmentally friendly composite adhesive.

[0124] Example 14: Preparation of a single-component water-oil mixed environmentally friendly composite adhesive

[0125] Without adding emulsifiers or dispersants, the oily adhesive prepared in Example 7 (Formula 1 in Table 2) and the vinyl acetate-acrylic emulsion adhesive (water-based adhesive) prepared in Example 4 (Formula 7 in Table 1) were compounded in a mass percentage ratio of 50:50 to prepare a single-component oil-water mixed environmentally friendly composite adhesive.

[0126] Experimental results: The composite adhesive is easy to thicken, does not separate, and has little odor.

[0127] The water- and oil-based adhesives of this invention serve as the base compounding reference for composite adhesives, with a solid content >50% and a viscosity of 5000-7500 Pa·s.

[0128] Example 15: Preparation of a single-component water-oil mixed environmentally friendly composite adhesive

[0129] Without adding emulsifiers or dispersants, the oily adhesive prepared in Example 8 (Formula 2 in Table 2) and the vinyl acetate-acrylic emulsion adhesive (water-based adhesive) prepared in Example 4 (Formula 7 in Table 1) were compounded in a mass percentage ratio of 50:50 to prepare a single-component oil-water mixed environmentally friendly composite adhesive.

[0130] Experimental results: The composite adhesive is not easy to thicken, does not separate, and has a strong odor.

[0131] Example 16 Preparation of a single-component water-oil mixed environmentally friendly composite adhesive

[0132] Without adding emulsifiers or dispersants, the oily adhesive prepared in Example 9 (Formula 3 in Table 2) and the vinyl acetate-acrylic emulsion adhesive (water-based adhesive) prepared in Example 4 (Formula 7 in Table 1) were compounded in a mass percentage ratio of 50:50 to prepare a single-component oil-water mixed environmentally friendly composite adhesive.

[0133] Experimental results: The composite adhesive showed significant tackification, did not separate into layers, and had a slightly stronger odor.

[0134] Example 17 Preparation of a single-component water-oil mixed environmentally friendly composite adhesive

[0135] Without adding emulsifiers or dispersants, the oily adhesive prepared in Example 10 (Formula 4 in Table 2) and the vinyl acetate-acrylic emulsion adhesive (water-based adhesive) prepared in Example 4 (Formula 7 in Table 1) were compounded in a mass percentage ratio of 50:50 to prepare a single-component oil-water mixed environmentally friendly composite adhesive.

[0136] Experimental results: The composite adhesive did not increase tack, did not separate, and had a strong odor.

[0137] Example 18: Preparation of a single-component water-oil mixed environmentally friendly composite adhesive

[0138] Without adding emulsifiers or dispersants, the oily adhesive prepared in Example 11 (Formula 5 in Table 2) and the vinyl acetate-acrylic emulsion adhesive (water-based adhesive) prepared in Example 4 (Formula 7 in Table 1) were compounded in a mass percentage ratio of 50:50 to prepare a single-component oil-water mixed environmentally friendly composite adhesive.

[0139] Experimental results: The composite adhesive has a large tackifier, is prone to clumping (difficult to control), has no flowability, and has a slightly weaker odor, which affects the bonding strength.

[0140] Example 19 Preparation of a single-component water-oil mixed environmentally friendly composite adhesive

[0141] Without adding emulsifiers or dispersants, the oily adhesive prepared in Example 12 (Formula 6 in Table 2) and the vinyl acetate-acrylic emulsion adhesive (water-based adhesive) prepared in Example 4 (Formula 7 in Table 1) were compounded in a mass percentage ratio of 50:50 to prepare a single-component oil-water mixed environmentally friendly composite adhesive.

[0142] Experimental results: The composite adhesive is easy to thicken, does not separate, and has little odor.

[0143] Example 20: Preparation of a single-component water-oil mixed environmentally friendly composite adhesive

[0144] Without adding emulsifiers or dispersants, the oily adhesive prepared in Example 13 (Formula 7 in Table 2) and the vinyl acetate-acrylic emulsion adhesive (water-based adhesive) prepared in Example 4 (Formula 7 in Table 1) were compounded in a mass percentage ratio of 50:50 to prepare a single-component oil-water mixed environmentally friendly composite adhesive.

[0145] Experimental results: The composite adhesive does not increase tack, is easy to separate, and has little odor.

[0146] This invention investigated the storage stability, washability, and initial tack of the single-component water-oil mixed environmentally friendly composite adhesives prepared in Examples 14-20. Storage stability was tested (referring to General Rules for Storage of Commonly Used Hazardous Chemicals BG15603-1995); washability was tested (referring to Test Method for Washability of Adhesive-Backed Clothing FZ / T80007.2-2006); initial tack was tested according to the standard initial tack test (GB / T4852-2002); and peel strength was tested (referring to Test Method for Peel Strength of Adhesive Tapes GB2792-2014).

[0147] The results are shown in Table 5:

[0148] Table 5 Results of storage stability, water resistance, and initial tack strength of composite adhesives

[0149]

[0150] The experiments showed that, considering the quality of the compounding process, the storage stability, water resistance, and initial tack strength of the composite adhesives, the composite adhesives prepared in Examples 14 (Formula 1 from Table 2 + Formulation 7 from Table 1), 16 (Formula 3 from Table 2 + Formulation 7 from Table 1), and 19 (Formula 6 from Table 2 + Formulation 7 from Table 1) all exhibited excellent performance. However, due to the strong odor of environmentally friendly composite adhesives containing methyl isobutyl ketone in practical applications, manufacturers generally do not recommend their use unless the materials are specifically designed for composite applications. Therefore, this invention selects Formulation 1 from Table 2, the oil-based adhesive, as the optimal formulation.

[0151] Comparing the peel strength of the original water-based adhesive and the composite adhesive, the water-oil composite adhesive of this invention exhibits a greater peel strength than the original water-based adhesive. Furthermore, the rate of increase in peel strength is also faster than that of the original water-based adhesive. Some composite products can even proceed directly to the next stage of product manufacturing.

[0152] In terms of water resistance, the water-oil composite adhesive of this invention exhibits greater water resistance than the original water-based adhesive. Water resistance tests show that the peel strength of the water-oil composite adhesive of this invention decreases less after washing than that of the original water-based adhesive.

[0153] In the preparation of the environmentally friendly composite adhesive of this invention, the viscosity of both the oil-based and water-based adhesive components is generally controlled between 5000 and 7500 Pa·s. During the compounding process of water-oil adhesives, due to the mutual repulsion of water and oil and the swelling effect of the solvent on the emulsion colloid, the compounding process easily leads to a dramatic increase in viscosity of the composite, limiting viscosity increase, and agglomeration, thus affecting the bonding effect of the composite adhesive. Furthermore, single-component water-oil mixed environmentally friendly composite adhesives are used with a wide variety of porous materials, requiring a relatively high system colloidal viscosity to prevent excessive material penetration and affecting the flexibility of the composite material. If only the viscosity of one phase is increased to meet the viscosity requirements of the overall adhesive, it can easily negatively impact the material penetration of the homogeneous colloid. Controlling the viscosity of the water and oil two-phase adhesives at a relatively low level, utilizing their complementary properties to increase the overall adhesive viscosity (generally controlled between 10000 and 20000 Pa·s), is a crucial aspect to consider during the compounding process. Therefore, determining the ratio of water-based adhesive to oil-based adhesive based on the qualitative properties of the water-based adhesive is key to evaluating the overall performance of a single-component water-oil hybrid environmentally friendly composite adhesive.

[0154] In the application of single-component water-oil hybrid environmentally friendly composite adhesives, the viscosity of the adhesive is subject to certain requirements because the composite materials are mostly porous. If the desired viscosity of the composite adhesive is achieved by combining a high-viscosity colloid from one component with a low-viscosity colloid from another, the inherent characteristics of the single adhesive component are often highlighted. It is difficult to achieve a low-viscosity adhesive by combining two high-viscosity systems. Only by combining two low-viscosity colloids can the viscosity of the composite adhesive be synergistically increased, resulting in better performance in terms of storage, strength, and overall complementary properties. Since water-based adhesives require system modifications to adjust properties, utilizing changes in the oil component to adjust the viscosity of the composite adhesive is the primary method in the formulation of water-oil composite adhesives. Simultaneously, establishing the solvent system of the oil-based adhesive plays a crucial role in the synergistic thickening effect of the composite adhesive.

[0155] In the preparation process of the oil-based adhesive in this invention, the solvent system in Examples 7-13 above serves two purposes, which differ from the solvent system requirements considered for general oil-based adhesives. The solvent added first in this invention prioritizes reactions that favor the graft polymerization of the oil-based portion, while the diluent (solvent) added later incorporates factors that promote the compatibility of the oil-based adhesive with the water-based adhesive in the oil-water mixture. Since the oil-based and water-based adhesives are components of a single-component composite adhesive system, and most composite adhesives are produced through mechanized assembly line operations, the selection of solvents should consider safety, environmental protection, and adaptability to composite equipment.

[0156] This invention uses toluene as the main solvent and xylene as a co-solvent. Because toluene is a weakly hydrogen-bonded and neutral solvent, insoluble in water, it cannot form hydrogen bonds with water, nor does it ionize to release hydrogen ions. Its molecular polarity is very low, and it can be approximated as a non-polar solvent. Therefore, toluene cannot form hydrogen bonds during application. However, as the main solvent in oil-based adhesives, toluene, when compounded with water-based adhesives, can slightly improve the tackifying effect, but has no significant impact on the adhesive strength. Although xylene has similar properties to toluene, it is a mixed type containing ortho-xylene and meta-xylene, making the hydrogen bonding effect of para-xylene difficult to control. Conventional xylene, as a solvent system for oil-based adhesives, when compounded with water-based adhesives, does not improve the tackifying effect but instead reduces viscosity, easily affecting the adhesive strength. Therefore, this invention uses xylene as a co-solvent for graft polymerization reactions. Although xylene is less toxic than toluene, it still falls into the category of "benzene, toluene, and xylene" solvents, and its usage should be controlled as much as possible. Methyl isobutyl ketone (Methyl Iobutyl ketone) has moderate hydrogen bonds, exhibiting both acidic and basic properties. It is slightly soluble in water and can form hydrogen bonds with water. As a non-polar solvent, Methyl Iobutyl ketone readily enhances tack and improves adhesive strength when used as a solvent system for oil-based adhesives, along with toluene, xylene, and Methyl Iobutyl ketone, and is compounded with water-based adhesives. The resulting adhesive is glossy and smooth.

[0157] Ethyl acetate has moderate hydrogen bonds and is a weak acid with low polarity. It is insoluble in water and cannot form hydrogen bonds with water. Therefore, when toluene, xylene, and ethyl acetate are used as solvents in oil-based adhesives and compounded with water-based adhesives, they do not improve the tackifying effect but tend to reduce viscosity and adhesive strength. Methanol has strong hydrogen bonds and is neutral. It does not ionize to produce hydrogen or hydroxide ions and can form hydrogen bonds with water. It has some hydrophilicity. Therefore, when toluene, xylene, and methanol are used as solvents in oil-based adhesives and compounded with water-based adhesives, they easily increase tack, but the adhesive strength is poor. When the proportions of the system are not properly controlled, it can easily cause clumping and loss of flowability. Cyclohexane is a cycloalkanes containing 6 carbon atoms, and its chemical properties are similar to those of alkanes.

[0158] Odor is not a consideration for certain special materials, therefore the organic solvent systems of the oily adhesives disclosed in this application are all feasible.

[0159] It is worth noting that the selection of the solvent system requires consideration not only of the role of the solvent-based adhesive in graft polymerization, but also of its inherent processing effect due to the presence of certain solvents. This results in embedding, penetration, and film formation in the composite material. This explains why single water-based adhesives do not have as wide a bonding surface as solvent-based adhesives. Therefore, the establishment of the solvent system should not only consider the requirements of two-phase compounding, but also the advantages of the bonding process. Selecting the solvent system for a two-phase adhesive is a comprehensive and balanced process.

[0160] In the preparation of the oil-based adhesive in this embodiment of the invention, the thermoplastic elastomer (SBS) in the raw material formulation has a linear and star-shaped structure, with a predominantly linear structure. Therefore, the graft polymerization process aims to generate linear polymers as much as possible, controlling the three-dimensional structure and preventing excessively rapid viscosity increase during graft polymerization. During the oil-water adhesive compounding process, based on the "island" theory, the aim is to generate "continental shelves" and "islands," and to create more "IPN" acceptors and acceptors through molecular entanglement. This is beneficial for the dispersion and affinity of the oil-water adhesive during two-phase compounding, making it easier to control the viscosity increase of the compound; it also improves the wettability of the adhesive during the compounding process, shortens the open process time of the adhesive in the compounding production line, and facilitates the achievement of composite bonding and shaping effects, meeting the safety and environmental protection requirements of the composite adhesive industry.

[0161] For oil-based adhesives, due to the characteristics of graft polymerization, the properties of the graft acceptor are subject to certain requirements. For example, the linear and star-shaped structures of thermoplastic elastomers have different morphologies, and the linear and branched graft structures differ accordingly. The viscosity of the star-shaped adhesive is much greater than that of the linear adhesive. In the same solvent system, the viscosity increases with the amount of star-shaped thermoplastic elastomer. In the same reactor, the viscosity of the star-shaped colloidal structure increases, while the average linear velocity decreases accordingly, providing a greater probability of collision between the thermoplastic elastomer and the monomer for the grafting reaction. Therefore, the rate of increase in viscosity and molecular weight of the grafted polymer is also faster. The stirring speed in the graft polymerization process also plays a decisive role in the grafted colloid. The oil-based adhesive of this invention is not the final adhesive product, but needs to be compounded with the water-based adhesive, and this is done without the addition of emulsifiers or dispersants. Therefore, the oily component of the adhesive needs to be considered from the perspective of the compounding system. Controlling the viscosity of the oily adhesive plays an important role in achieving the final viscosity and application performance of the entire compound.

[0162] In the preparation of the oily portion of the adhesive in this invention, phenolic resin 2402 is preferred as the functional resin. This is to utilize the hydroxyl groups in the resin to maximize the molecular weight of the oily portion of the adhesive while reducing the amount of star-shaped thermoplastic elastomer involved, thereby improving the water resistance, adhesion, and bonding strength of the composite adhesive. Following the "island" theory in the compounding process, the aim is to generate as many "continental shelves" and "islands" as possible. Since the thermoplastic elastomer in the oily adhesive is highly hydrophobic, the functional monomer can be a carboxyl / hydroxyl-containing monomer. The purpose is to create islands that allow hydrophilic monomers to be introduced into the oily adhesive, providing affinity for the water-based adhesive when compounding water-oil adhesives without the need for emulsifiers or dispersants. Therefore, carboxyl / hydroxyl monomers are preferred as the functional monomer. The synergist mentioned in this invention is determined based on the properties of the water-based adhesive and the requirements of the composite material, and may be omitted. The synergist is added to the oily adhesive in a cold addition manner to ensure the performance of the original synergist. The addition of synergists enhances the affinity between the oil and water phases, improving the adhesion, bonding strength, water resistance, washability, solvent resistance, and temperature resistance of the composite adhesive. KH-550, KH-560, KH-570, Tween 80, and OP-10 are preferred. Among these, the silane coupling agents have a small increase in viscosity when used in oil-water adhesive blends. However, the addition of Tween 80 significantly increases the viscosity of the blended adhesive. If viscosity increases during blending, deionized water can be added to lower the viscosity, resulting in a very noticeable decrease and making the blending process controllable. Therefore, in this embodiment of the invention, the nonionic surfactant polysorbate-80 (Tween-80) is the preferred choice.

[0163] Comprehensive analysis revealed that the combination of the water-based adhesive formulation 7 and the oil-based adhesive formulation 1 of this invention yields the best two-phase adhesive effect.

[0164] The composite adhesive of this invention utilizes existing solvent-based composite equipment, requiring no equipment modification to meet the entire composite process. This is another highlight of the water-oil composite adhesive of this invention, and also an aspect that makes it superior to current water-based adhesives in the current composite field.

[0165] The composite adhesive prepared in this invention was compared with the composite adhesive prepared in Chinese Patent CN11374222A, "A Semi-Oil-Semi-Water Composite Adhesive and Its Preparation Method," published by the inventor in 2021 (Examples 1-3 of which serve as Comparative Examples 8-10). The composite adhesive materials (without surface polarization treatment) were tested according to the standard GB / T532-2008, "Determination of Adhesion Strength between Vulcanized Rubber or Thermoplastic Rubber and Fabric," after 5, 10, and 20 days (23°C). The results are shown in Table 6.

[0166] Table 6 Comparison of peel strength at 90° or 180° (N / cm)

[0167]

[0168] The peel strength of the composite adhesives in Examples 14, 16, and 19 of this invention is superior to that of the composite adhesive in Chinese Patent CN11374222A "A Semi-Oil Semi-Water Composite Adhesive and Its Preparation Method", and the degree of damage to the composite material is particularly outstanding.

[0169] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A single-component water-oil mixed environmentally friendly composite adhesive aqueous part adhesive, characterized in that, It is prepared by the following steps: (1) monomer pre-emulsification: 622 parts of deionized water are injected into the reaction kettle, stirring is started and 88 parts of emulsifier LA300 / SB, 25 parts of 13.56% by mass polyvinyl alcohol PVA 1788 solution, 40 parts of acrylamide are added, dispersion is carried out, the dispersion time is controlled at 120 min, 11 parts of methyl methacrylate MMA, 100 parts of acrylic acid AA, 1103 parts of vinyl acetate, 987 parts of butyl acrylate, 75 parts of styrene, 10 parts of functional monomer methacrylic acid are added, and dispersion is continued for 30-50 min for standby; (2) Seed emulsion polymerization: 634 parts of deionized water are injected into the reaction kettle, stirring is started and a certain amount of emulsifier LA300 / SB 132 parts, organic solvent toluene 120 parts, buffer baking soda 14 parts are added, dispersion is carried out for 30 min, then heating is started, and the temperature is raised to 65℃, then heating is stopped, when the temperature in the reaction kettle rises to 68℃, 8% of the total amount of emulsion previously emulsified in step (1) is added as emulsion seed and initiator B, 24.4 parts of 13.9% by mass APS aqueous solution is pre-polymerized; (3) Emulsion polymerization: When the temperature in the reaction kettle naturally rises to 78℃ and the reaction kettle shows blue light phenomenon, the remaining emulsion and initiator C, 138.7 parts of 1.23% by mass APS aqueous solution are added at the same time, the emulsion dropwise adding time is controlled at 240 min, the initiator C dropwise adding time is controlled at 270 min, and the temperature is controlled at 80℃-85℃ during dropwise adding; (4) Emulsion formation: After the emulsion dropwise adding is completed, the initiator dropwise adding is continued for 60 min, and then cooling is carried out; (5) Emulsion adjustment: When the temperature drops to 70℃, secondary dropwise adding is carried out, 1.5 parts of ivory block + 8 parts of deionized water, 17.5 parts of tert-butyl hydroperoxide + 8 parts of deionized water, the dropwise adding time is controlled at 30 min, after dropwise adding, aging is carried out, the aging time is controlled at 20 min, and then cooling is carried out; (6) Emulsion reinforcement: When the temperature drops to 45℃, 15 parts of resin mixed solution, hydrogenated rosin and toluene 1:1 are added, aging is carried out, and the aging time is controlled at 90 min; The single-component water-oil mixed type environment-friendly composite adhesive water-based part adhesive is prepared.

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