Aqueous acrylic contact latex, method of preparation and use thereof

Abstract

The application discloses a kind of aqueous acrylic contact latex emulsion, preparation method and application thereof, the emulsion contains the following components: with the hard monomer of styrene, methyl methacrylate, acrylic acid, with the soft monomer of isooctyl acrylate, butyl acrylate, ethyl acrylate, with the functional monomer of hydroxyethyl acrylate, beta-acryloyl oxypropionic acid, seed emulsion, emulsifier, inorganic salt, oxidant, reducing agent, post-adding auxiliary agent etc. are formed. The application adopts special process formula, fully balances production stability and product performance, the mechanical stability of the obtained emulsion production process is good, and the product initial adhesion, holding adhesion, wet adhesion performance is excellent.

Description

Technical Field

[0001] This invention relates to the field of waterborne acrylic emulsion technology, specifically to a waterborne acrylic contact adhesive emulsion, its preparation method, and its application. Background Technology

[0002] Contact adhesives are applied between two materials to be bonded. After drying and bonding, they form a strong bond without the need for pressure. They are mainly used in the manufacture of footwear and leather goods, including sporting goods, clothing, furniture, and accessories. They are also used to bond various parts of shoes, such as soles and uppers. Acrylic contact adhesives offer advantages such as being environmentally friendly, resistant to yellowing, and cost-effective. Furthermore, contact adhesives are copolymerized from acrylic monomers, allowing for significant performance flexibility.

[0003] Contact adhesives generally require high solids content, which is beneficial for drying and adhesion. However, when the solids content of acrylic emulsions exceeds 64%, the viscosity increases sharply during processing, making it impossible to prepare the emulsion normally. Simultaneously, to improve adhesion, the glass transition temperature of the formulation is generally low during product design, giving the product shear demulsification characteristics. However, in industrial production, when the emulsion has poor shear resistance, stable production is impossible. Therefore, a perfect balance cannot be achieved between performance and stable production for this type of product. Furthermore, relying solely on a low glass transition temperature does not guarantee the required adhesion performance. Summary of the Invention

[0004] To address the challenges of poor wet adhesion and bonding performance, as well as instability in industrial production, of water-based acrylic contact adhesives, this invention aims to provide a water-based acrylic adhesive emulsion. The emulsion, formulated using the special process of this invention, has a high solids content, low process viscosity, wide molecular weight distribution, and stable industrial production. Furthermore, during downstream use, the shearing action of roller coating can achieve demulsification, resulting in excellent wet adhesion and bonding performance of the emulsion. Ultimately, a perfect balance between performance and industrial production can be achieved.

[0005] Another object of the present invention is to provide a method for preparing such an aqueous acrylic contact adhesive emulsion.

[0006] Another object of the present invention is to provide the application of this water-based acrylic contact latex.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0008] An aqueous acrylic contact adhesive latex comprising the following components in parts by weight:

[0009]

[0010] In a preferred embodiment, the aqueous acrylic contact latex has a solids content of 65wt%-67wt% and a particle size of 300-500nm.

[0011] In one specific embodiment, the hard monomer is selected from any one or more combinations of butyl methacrylate, acrylamide, methyl methacrylate, styrene, acrylic acid, and methacrylic acid. Preferably, the hard monomer is selected from a combination of acidic monomers containing acrylic acid and / or methacrylic acid. More preferably, the acidic monomer accounts for 18-21% of the total monomer weight.

[0012] In one specific implementation, the soft monomer is selected from any one or more of allyl methacrylate, isooctyl acrylate, butyl acrylate, and ethyl acrylate.

[0013] In one specific implementation, the functional monomer is selected from one or two of diacetone acrylamide, hydroxyethyl methacrylate, hydroxyethyl acrylate, and β-acryloyloxypropionic acid.

[0014] In one specific embodiment, the finished seed emulsion is a commercially available water-based acrylic emulsion with a particle size of 60-120 nm and a solid content of 41-43 wt%, preferably with a particle size of 90-120 nm.

[0015] In one specific embodiment, the emulsifier is any one or a combination of COPS-1, sodium tridecyl alcohol polyoxyethylene ether sulfate, AE-07, AE-09, sodium salt of sulfonated diphenyl ether tetrapropylene derivative, polyoxyethylene polystyrene phenolic ether, sodium allyl ether hydroxypropyl sulfonate, and sodium dodecyl sulfate; preferably, the emulsifier is selected from a combination containing AE-07 and / or AE-09, more preferably, the AE-07 and AE-09 type emulsifiers account for 0.8-1.5% of the total monomer weight.

[0016] In one specific implementation, the pre-emulsion additive includes at least one of a chain transfer agent and a buffer; preferably, the chain transfer agent is one of n-dodecyl mercaptobutyl ester and the buffer is one of sodium bicarbonate, sodium carbonate, and ammonia.

[0017] In one specific implementation, the oxidant is one or more of ammonium persulfate, sodium persulfate, tert-butyl hydroperoxide, and hydrogen peroxide.

[0018] In one specific implementation, the reducing agent is one or more of sodium metabisulfite, isoascorbic acid, sodium hydrosulfite, sodium formaldehyde sulfoxylate, and FF6.

[0019] In one specific implementation, the inorganic salt is one or more of sodium sulfate, potassium sulfate, ammonium sulfate, sodium carbonate, and sodium bicarbonate.

[0020] In one specific implementation scheme, the added auxiliary agent includes at least one of the neutralizing agents, defoamers, and preservatives commonly used in emulsion polymerization.

[0021] On the other hand, the aforementioned method for preparing the aqueous acrylic contact latex includes the following steps:

[0022] (1) Add deionized water to the reactor and heat it to 65-95℃. Add emulsifier and finished seed emulsion to the bottom of the reactor.

[0023] (2) At 65-95℃, add the first oxidant to the reactor. Preferably, after 1-15 min, add the pre-emulsion I and the second oxidant to the reactor. At the same time, add the pre-emulsion II to the pre-emulsion I at a certain rate until all the pre-emulsions are added. Preferably, the total time for adding is 180-360 min.

[0024] (3) Keep warm for 30-60 minutes, cool down to 55-75℃, and simultaneously add optional post-treatment oxidant and reducing agent, preferably for 30-60 minutes. Then continue to add inorganic salt solution, preferably for 20-40 minutes. After the addition is completed, keep warm. During the warming process, test the particle size of the product. When the particle size reaches 400-430nm, then quickly cool down to below 50℃. The cooling time should be ≤30 minutes. Then add the post-additional additives, adjust the pH to 3.0-6.5, and filter out the material.

[0025] In one specific embodiment, the preemulsion I comprises the following components, based on the total mass of preemulsion I:

[0026]

[0027]

[0028] In one specific embodiment, the preemulsion II comprises the following components, based on the total mass of preemulsion II:

[0029] 10-35 parts by weight of the finished seed emulsion, preferably 25-30 parts by weight;

[0030] The pre-emulsion additive is used in amounts of 0.6-3 parts by weight, preferably 0.9-2.6 parts by weight;

[0031] 5-15 parts by weight of water, preferably 5-10 parts by weight.

[0032] On the other hand, the aforementioned water-based acrylic contact adhesive emulsion is used in contact adhesives.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] This invention avoids the problems of low Tg, poor shear stability, and inability to be industrialized of conventional adhesive products by ingeniously designing a composition of hard monomers, soft monomers, and functional monomers, emulsifiers, and the addition of inorganic salts. At the same time, the product has excellent initial tack, wet adhesion, and holding power. Detailed Implementation

[0035] To better understand the technical solution of the present invention, the following embodiments will further illustrate the method provided by the present invention. However, the present invention is not limited to the listed embodiments, but should also include any other known modifications within the scope of the claims of the present invention.

[0036] An aqueous acrylic contact adhesive latex comprising the following components in parts by weight:

[0037]

[0038]

[0039] The pre-emulsion additive includes at least one of chain transfer agents and buffers. The post-added additive includes at least one of neutralizing agents, defoamers, and preservatives commonly used in emulsion polymerization.

[0040] In one specific embodiment, the aqueous acrylic contact latex comprises the following components in parts by weight:

[0041] The hard monomer is 140-160 parts by weight (e.g., 141 parts by weight, 142 parts by weight, 143 parts by weight, 144 parts by weight, 145 parts by weight, 146 parts by weight, 147 parts by weight, 148 parts by weight, 149 parts by weight, 150 parts by weight, 151 parts by weight, 152 parts by weight, 153 parts by weight, 154 parts by weight, 155 parts by weight, 156 parts by weight, 157 parts by weight, 158 parts by weight, 159 parts by weight, etc.), preferably 145-155 parts by weight;

[0042] The soft monomer is 400-550 parts by weight (e.g., 410 parts by weight, 420 parts by weight, 430 parts by weight, 440 parts by weight, 450 parts by weight, 460 parts by weight, 470 parts by weight, 480 parts by weight, 490 parts by weight, 500 parts by weight, 510 parts by weight, 520 parts by weight, 530 parts by weight, 540 parts by weight, etc.), preferably 430-500 parts by weight;

[0043] The functional monomer is 10-30 parts by weight (e.g., 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, 20 parts by weight, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight, etc.), preferably 15-25 parts by weight;

[0044] The finished seed emulsion is 20-60 parts by weight (e.g., 22 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 28 parts by weight, 30 parts by weight, 32 parts by weight, 34 parts by weight, 35 parts by weight, 36 parts by weight, 38 parts by weight, 40 parts by weight, 42 parts by weight, 44 parts by weight, 45 parts by weight, 46 parts by weight, 48 parts by weight, 50 parts by weight, 52 parts by weight, 54 parts by weight, 55 parts by weight, 56 parts by weight, 58 parts by weight, etc.), preferably 30-50 parts by weight;

[0045] The emulsifier is 5-20 parts by weight (e.g., 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, 20 parts by weight, etc.), preferably 7-18 parts by weight;

[0046] The chain transfer agent is used in amounts of 0.5-2 parts by weight (e.g., 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1.0 parts by weight, 1.1 parts by weight, 1.2 parts by weight, 1.3 parts by weight, 1.4 parts by weight, 1.5 parts by weight, 1.6 parts by weight, 1.7 parts by weight, 1.8 parts by weight, 1.9 parts by weight, 2 parts by weight, etc.), preferably 0.7-1.8 parts by weight;

[0047] The buffer is provided in 0.1-1 parts by weight (e.g., 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1 part by weight, etc.), preferably 0.2-0.8 parts by weight;

[0048] The oxidant is 2-8 parts by weight (e.g., 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, etc.), preferably 3-7 parts by weight;

[0049] The reducing agent is 0.4-2 parts by weight (e.g., 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1.0 parts by weight, 1.1 parts by weight, 1.2 parts by weight, 1.3 parts by weight, 1.4 parts by weight, 1.5 parts by weight, 1.6 parts by weight, 1.7 parts by weight, 1.8 parts by weight, 1.9 parts by weight, 2 parts by weight, etc.), preferably 0.5-1.5 parts by weight;

[0050] 5-10 parts by weight of inorganic salt (e.g., 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, etc.), preferably 6-8 parts by weight;

[0051] Neutralizing agent: 0.5-2 parts by weight (e.g., 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1.0 parts by weight, 1.1 parts by weight, 1.2 parts by weight, 1.3 parts by weight, 1.4 parts by weight, 1.5 parts by weight, 1.6 parts by weight, 1.7 parts by weight, 1.8 parts by weight, 1.9 parts by weight, 2 parts by weight, etc.), preferably 0.7-1.5 parts by weight;

[0052] The defoamer is used in amounts of 0.1-1 parts by weight (e.g., 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1 part by weight, etc.), preferably 0.2-0.8 parts by weight;

[0053] The preservative is 1-4 parts by weight (e.g., 1 part by weight, 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight, etc.), preferably 1.5-3.5 parts by weight;

[0054] Water 260-340 parts by weight (e.g., 260 parts by weight, 270 parts by weight, 280 parts by weight, 290 parts by weight, 300 parts by weight, 310 parts by weight, 320 parts by weight, 330 parts by weight, 340 parts by weight, etc.), preferably 270-330 parts by weight.

[0055] The aqueous acrylic contact latex of the present invention preferably has a solid content of 65-67 wt% (e.g., 65.5 wt%, 66 wt%, 66.5 wt%, etc.) and a particle size of 300-500 nm (e.g., 350 nm, 400 nm, 450 nm, etc.).

[0056] The above-mentioned water-based acrylic contact latex can be prepared using the conventional methods of the present invention, without any particular limitations. For example, the following methods can be used, but are not limited thereto.

[0057] A method for preparing an aqueous acrylic contact adhesive includes the following steps:

[0058] (1) Add deionized water to the reactor, heat it to 65-95℃, preferably 80-95℃, and add the bottom emulsifier solution and the finished seed emulsion.

[0059] (2) At 65-95℃, preferably 80-95℃, add the first oxidant solution to the reactor, 1-

[0060] After 15 minutes, preferably after 1-5 minutes, pre-emulsion I and the second oxidant are added dropwise to the reactor. At the same time, pre-emulsion II is added dropwise to pre-emulsion I at a certain rate until all the pre-emulsion is added. The total time for adding is 180-360 minutes, preferably 180-240 minutes.

[0061] (3) Keep warm for 30-60 min, cool down to 55-75℃, preferably 70-75℃, and simultaneously add optional post-treatment oxidant and reducing agent solutions for 30-60 min. Then continue to add inorganic salt solution for 20-40 min. After the addition is completed, keep warm. During the warming process, test the particle size of the product. When the particle size reaches 400-430 nm, then quickly cool down to below 50℃, preferably to 40-50℃. The cooling time should be ≤30 min. Then add neutralizing agent to neutralize and adjust the pH to 3.0-6.5, preferably to 4.5-5.5. Continue to add defoamer and preservative, and filter out the material.

[0062] In step (1) of this invention, the emulsifier in the bottom emulsifier solution is one or more of COPS-1, sodium tridecyl alcohol polyoxyethylene ether sulfate, AE-07, AE-09, sodium salt of sulfonated diphenyl ether tetrapropylene derivative, polyoxyethylene polystyrene phenolic ether, and sodium allyl ether hydroxypropyl sulfonate, for example, BASF AE-07 or AE-09. Preferably, the emulsifier is selected from a combination containing AE-07 and / or AE-09, that is, in addition to AE-07 or AE-09 type emulsifiers, it also contains other types of emulsifiers selected above. More preferably, AE-07 and AE-09 type emulsifiers account for 0.8-1.5% of the total monomer weight. Wherein, the total monomer weight is the sum of the weights of hard monomers, soft monomers, and functional monomers.

[0063] In this invention, the emulsifier is added in two parts: one part is used as the bottom emulsion, and the other part is added to the pre-emulsion I. The total amount of the two parts is 5-20 parts by weight. In practice, there is no particular limitation on the ratio of these two parts. For example, in this step, the amount of bottom emulsifier is 1-10 parts by weight, such as 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, etc., preferably 5-8 parts by weight.

[0064] In step (1) of this invention, the finished seed emulsion is a commercially available water-based acrylic emulsion with a particle size of 60-120 nm, such as 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, etc., and a solid content of 41-43 wt%. Preferably, the finished seed emulsion has a particle size of 90-120 nm, such as a particle size of 110 nm, and a solid content of 42%, such as the water-based acrylic emulsion product of Wanhua Chemical. Those skilled in the art will understand that the amount of finished seed emulsion added is related to the solid content; a higher solid content requires less addition, and a lower solid content requires more addition. This invention uses a finished emulsion with a 42% solid content as an example, but this is only an example; other solid content schemes should also be within the scope of protection of this invention.

[0065] In this invention, the finished seed emulsion is added in two parts: one part is used as the bottom liquid, and the other part is added to the pre-emulsion II. The total amount of the two parts should be 20-60 parts by weight. In practice, there is no particular limitation on the ratio of these two parts. For example, in this step, the amount of finished seed emulsion added is 10-25 parts by weight, preferably 10-20 parts by weight.

[0066] In step (2) of this invention, the first and second oxidants are one or more of ammonium persulfate or sodium persulfate, tert-butyl hydrogen peroxide, and hydrogen peroxide, preferably ammonium persulfate or sodium persulfate. In this step, the amount of oxidant used is, for example, 1-6 parts by mass, such as 1 part, 2 parts, 3 parts, 4 parts, 5 parts by mass, etc., preferably accounting for 60%-80% of the total weight of the oxidant, preferably 3-7 parts by mass. The remaining part is an optional post-treatment oxidant. The ratio of the first oxidant to the second oxidant is not particularly limited; for example, the two parts can be evenly distributed. The first and second oxidants can be the same or different, preferably the same oxidant. According to conventional practice in the art, to facilitate the dropwise addition of the second oxidant to the reaction vessel, a relatively large amount of water can be added appropriately to facilitate the dropwise addition of the second oxidant; this is conventional practice in the art.

[0067] The pre-emulsion I in step (2) of this invention comprises the following components, based on the total mass of pre-emulsion I:

[0068]

[0069] The preparation method of the preemulsion I is not particularly limited, and may include the following steps: adding water, emulsifier, soft monomer, functional monomer and hard monomer to the preemulsification tank 1, and stirring at high speed for 10-30 minutes.

[0070] The emulsifier in the pre-emulsion I is any one or more selected from COPS-1, sodium tridecyl alcohol polyoxyethylene ether sulfate, AE-07, AE-09, sodium salt of sulfonated diphenyl ether tetrapropylene derivative, polyoxyethylene polystyrene phenolic ether, and sodium dodecyl sulfate. Preferably, the emulsifier is selected from a combination containing AE-07 and / or AE-09, that is, in addition to AE-07 or AE-09 type emulsifiers, it also contains other types of emulsifiers selected above. More preferably, AE-07 and AE-09 type emulsifiers account for 0.8-1.5% of the total monomer weight, and the total monomer weight is the sum of the weights of hard monomers, soft monomers, and functional monomers. The amount of emulsifier used is 4-10 parts by weight, for example, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 9 parts by weight, 10 parts by weight, etc., preferably 5-10 parts by weight.

[0071] The hard monomers in the preemulsion I comprise one or more combinations of butyl methacrylate, acrylamide, methyl methacrylate, styrene, methacrylic acid, and acrylic acid. Preferably, the hard monomers are selected from combinations of acidic monomers containing acrylic acid and / or methacrylic acid; more preferably, the acidic monomers account for 18-21% of the total monomer weight. For example, the hard monomers are a mixture of styrene, methacrylic acid, and acrylic acid, and the amount of methacrylic acid and / or acrylic acid is preferably 18-21% of the total monomer weight. In preemulsion I, the amount of hard monomer added is 140-160 parts by weight (e.g., 141 parts by weight, 142 parts by weight, 143 parts by weight, 144 parts by weight, 145 parts by weight, 146 parts by weight, 147 parts by weight, 148 parts by weight, 149 parts by weight, 150 parts by weight, 151 parts by weight, 152 parts by weight, 153 parts by weight, 154 parts by weight, 155 parts by weight, 156 parts by weight, 157 parts by weight, 158 parts by weight, 159 parts by weight, etc.), preferably 145-155 parts by weight.

[0072] The soft monomers in the preemulsion I include one or more of allyl methacrylate, isooctyl acrylate, butyl acrylate, and ethyl acrylate. The amount of soft monomers added is 400-550 parts by weight (e.g., 410 parts by weight, 420 parts by weight, 430 parts by weight, 440 parts by weight, 450 parts by weight, 460 parts by weight, 470 parts by weight, 480 parts by weight, 490 parts by weight, 500 parts by weight, 510 parts by weight, 520 parts by weight, 530 parts by weight, 540 parts by weight, etc.), preferably 430-500 parts by weight.

[0073] The functional monomers in the preemulsion I include one or more of diacetone acrylamide, hydroxyethyl methacrylate, hydroxyethyl acrylate, and β-acryloyloxypropionic acid. The amount of the functional monomers added is 10-30 parts by weight (e.g., 11 parts by weight, 12 parts by weight, 13 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 17 parts by weight, 18 parts by weight, 19 parts by weight, 20 parts by weight, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight, etc.), preferably 15-25 parts by weight.

[0074] The pre-emulsion II in step (2) of this invention comprises the following components, based on the total mass of pre-emulsion II:

[0075] 20-35 parts by weight of the finished seed emulsion, preferably 25-30 parts by weight;

[0076] The pre-emulsion additive is used in amounts of 0.6-3 parts by weight, preferably 0.9-2.6 parts by weight;

[0077] 5-15 parts by weight of water, preferably 5-10 parts by weight.

[0078] Among them, pre-emulsion additives include at least buffers and chain transfer agents.

[0079] The preparation method of the preemulsion II is not particularly limited, and may include the following steps: adding the finished seed emulsion, buffer and chain transfer agent to the preemulsification tank 2, and stirring at high speed for 10-30 minutes.

[0080] The pre-emulsion II uses a commercially available aqueous acrylic emulsion with a particle size of 60-120 nm, such as 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, etc., and a solid content of 41-43 wt%. Preferably, the particle size of the pre-emulsion is 90-120 nm, such as 110 nm, and the solid content is 42%, such as the aqueous acrylic emulsion product from Wanhua Chemical. Those skilled in the art will understand that the amount of pre-emulsion added is related to the solid content; a higher solid content requires less addition, and a lower solid content requires more addition. This invention uses a pre-emulsion with a 42% solid content as an example, but this is only an example; other solid content schemes should also be within the scope of protection of this invention. The pre-emulsion used in this step is the same as the pre-emulsion used in the bottom liquid of step (1). In this step, the amount of finished seed emulsion added is 10-35 parts by weight, such as 10 parts by weight, 12 parts by weight, 14 parts by weight, 15 parts by weight, 16 parts by weight, 18 parts by weight, 20 parts by weight, 21 parts by weight, 22 parts by weight, 23 parts by weight, 24 parts by weight, 25 parts by weight, 26 parts by weight, 27 parts by weight, 28 parts by weight, 29 parts by weight, 30 parts by weight, 31 parts by weight, 32 parts by weight, 33 parts by weight, 34 parts by weight, 35 parts by weight, etc., preferably 25-30 parts by weight.

[0081] In step (2) of the present invention, the buffer is one or more of sodium bicarbonate, sodium carbonate, and ammonia, and the amount used is 0.1-1 parts by weight, for example, 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1 part by weight, etc., preferably 0.2-0.8 parts by weight. The chain transfer agent is selected from either n-dodecyl mercaptobutyl ester or thiobutyrate. The amount of chain transfer agent added is 0.5-2 parts by mass, for example, 0.5 parts by mass, 0.6 parts by mass, 0.7 parts by mass, 0.8 parts by mass, 0.9 parts by mass, 1 part by mass, 1.1 parts by mass, 1.2 parts by mass, 1.3 parts by mass, 1.4 parts by mass, 1.5 parts by mass, 1.6 parts by mass, 1.7 parts by mass, 1.8 parts by mass, 1.9 parts by mass, 2 parts by mass, etc., preferably 0.7-1.8 parts by mass.

[0082] In step (3) of the present invention, the post-treatment oxidant is 1-2 parts by mass, such as 1 part by mass, 2 parts by mass, etc., preferably 2 parts by mass. The post-treatment oxidant is preferably tert-butyl hydrogen peroxide, which is mainly used to remove the odor from the product. This is a conventional operation well known to those skilled in the art, and can also be selectively added according to actual needs.

[0083] In step (3) of the present invention, the amount of the post-treatment reducing agent is 0.4-2 parts by weight, for example, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1.0 parts by weight, 1.1 parts by weight, 1.2 parts by weight, 1.3 parts by weight, 1.4 parts by weight, 1.5 parts by weight, 1.6 parts by weight, 1.7 parts by weight, 1.8 parts by weight, 1.9 parts by weight, 2 parts by weight, etc., preferably 0.5-1.5 parts by weight. The reducing agent is one or more of sodium metabisulfite, isoascorbic acid, sodium hydrosulfite, sodium formaldehyde sulfoxylate, and FF6, preferably ascorbic acid.

[0084] In step (3) of the present invention, the inorganic salt is one or more of sodium sulfate, potassium sulfate, ammonium sulfate, sodium carbonate, and sodium bicarbonate, preferably sodium sulfate, and the amount used is 5-10 parts by mass, for example 5 parts by mass, 6 parts by mass, 7 parts by mass, 8 parts by mass, 9 parts by mass, 10 parts by mass, etc., preferably 0.5-1.5 parts by mass.

[0085] In step (3) of this invention, the neutralizing agent is preferably ethanolamine and / or NaOH solution, and the amount used is 0.5-2 parts by mass, for example 0.5 parts by mass, 0.6 parts by mass, 0.7 parts by mass, 0.8 parts by mass, 0.9 parts by mass, 1.0 parts by mass, 1.1 parts by mass, 1.2 parts by mass, 1.3 parts by mass, 1.4 parts by mass, 1.5 parts by mass, 1.6 parts by mass, 1.7 parts by mass, 1.8 parts by mass, 1.9 parts by mass, 2 parts by mass, etc., preferably 0.7-1.5 parts by mass.

[0086] In step (3) of the present invention, the defoamer is preferably Evonik Degussa Tego-825 and / or Tego-1488, and the amount used is 0.1-1 parts by weight, for example 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, 1 part by weight, etc., preferably 0.2-0.8 parts by weight.

[0087] In step (3) of the present invention, the preservative is preferably an isothiazolinone-based MIT preservative, and the amount used is 1-4 parts by weight, such as 1 part by weight, 1.5 parts by weight, 2 parts by weight, 2.5 parts by weight, 3 parts by weight, 3.5 parts by weight, 4 parts by weight, etc., preferably 1.5-3.5 parts by weight.

[0088] This invention, through a clever design involving hard monomers, soft monomers, and functional monomers, emulsifiers, and the subsequent addition of inorganic salts, avoids the problems of low Tg, poor shear stability, and inability to be industrially produced found in conventional adhesive products. Simultaneously, the product exhibits excellent initial tack, wet adhesion, and holding power. The relevant explanations are as follows:

[0089] First, the pre-emulsion requires a high acid content. In the monomer composition, the acid content is much higher than that of conventional acrylic contact latex (1-5%). This is because it is necessary to ensure that the molecular chains have high hydrophilicity. When inorganic salts are added subsequently and the emulsifier at the bottom of the vessel migrates into the latex particles, the molecular chains can also migrate to the surface of the latex particles simultaneously. This synergistic effect allows the latex particles to quickly reach a metastable state.

[0090] Secondly, by pre-embedding AE-07 type emulsifier at the bottom of the reactor, it has a good migration effect on acid monomers during the reaction stage, avoiding excessive nucleation in the aqueous phase, ensuring the polymerization stability under high acid conditions, and also providing the prerequisite for instability in the post-elimination stage.

[0091] Finally, in the post-elimination stage, the addition of inorganic salts lowers the cloud point of the AE-07 emulsifier, causing the emulsifier to gradually migrate into the interior of the latex particles and the more hydrophilic molecular chains to migrate to the surface of the latex particles. This results in a thinning of the hydration layer on the surface of the latex particles, leading to an unstable state. The latex particles transition from a stable state to an aggregated state. During the heat preservation stage, particle size is strictly monitored through particle size detection. Ideally, when the particle size gradually increases to 400-430 nm, the temperature is rapidly reduced. To prevent further aggregation, which would reduce the stability of the emulsion and cause sludge discharge, the cooling time is controlled within 30 minutes. The resulting emulsion, when applied by spraying or roller coating, will undergo demulsification under shear, greatly improving the wet adhesion performance of the acrylic contact adhesive emulsion and exhibiting excellent bonding properties.

[0092] In summary, this invention, through ingenious overall formulation design, produces an emulsion with stable polymerization stage and excellent key adhesion and wet adhesion properties, balancing the relationship between product production stability and performance, and solving a problem in this industry.

[0093] The present invention will be further illustrated by more specific embodiments below, but these do not constitute any limitation.

[0094] In the following embodiments, portions are by weight unless otherwise specified.

[0095] Table 1 Raw materials used in the preparation of acrylic contact adhesive latex

[0096]

[0097]

[0098] Example 1: Emulsion 1-1

[0099] Pre-emulsion I preparation: 95.7 parts deionized water (DIW), 3.3 parts sodium salt of sulfonated diphenyl ether tetrapropylene derivative 2A1, 3.3 parts polyoxyethylene polystyrene phenolic ether 710, 133 parts isooctyl acrylate (EHA), 8.5 parts hydroxyethyl acrylate, 9.5 parts β-acryloyloxypropionic acid, 175 parts butyl acrylate (BA), 125 parts ethyl acrylate (EA), 75 parts methacrylate (MAA), 50 parts acrylic acid (AA), and 25 parts styrene (ST) were prepared in pre-emulsification tank 1 and stirred thoroughly.

[0100] Pre-emulsion II preparation: 26.1 parts of finished seed emulsion, 0.4 parts of sodium bicarbonate, 1.3 parts of n-dodecyl mercaptan (N-DM), and 7 parts of deionized water were prepared in pre-emulsification tank 2 and stirred thoroughly.

[0101] Weigh 0.9 parts of ammonium persulfate (APS) and dissolve it in 10 parts of deionized water (DIW) to prepare the first oxidant solution; weigh 2.0 parts of ammonium persulfate (APS) and dissolve it in 30 parts of deionized water (DIW) to prepare the second oxidant solution.

[0102] Add 110 parts of deionized water to the reactor and heat to 70°C. Add 3.3 parts of sodium allyl ether hydroxypropyl sulfonate COPS-1, 7 parts of ethoxylated C12-14 alcohol AE-07, and 13.3 parts of the finished seed emulsion. Add the first oxidant solution to the reactor, and after 3 minutes, add the pre-emulsion I solution and the second oxidant solution dropwise, controlling the reaction temperature at 70°C. Simultaneously, add pre-emulsion II dropwise to pre-emulsion I until all the solution is added, with a dropwise addition time of 180 minutes. After holding at the temperature for 45 minutes, the material in the reactor was cooled to 60°C. 2 parts of tert-butyl hydroperoxide (TBHP) dissolved in 10 parts of deionized water (DIW) and 0.8 parts of isoascorbic acid (IAA) dissolved in 10 parts of deionized water (DIW) were added dropwise over 40 minutes. Then, 6 parts of sodium sulfate dissolved in 50 parts of water were added dropwise at 60°C over 30 minutes. The temperature was then maintained while monitoring the particle size. After 10-20 minutes of maintaining the temperature, the particle size increased to 400-430 nm. The temperature was then rapidly reduced to 50°C over 20 minutes. 2 parts of MEA were then added for neutralization, along with 0.4 parts of defoamer (Tego-825) and 1.9 parts of preservative (Kordek MLX), resulting in emulsion 1-1.

[0103] Example 2: Emulsion 1-2

[0104] Pre-emulsion I preparation: 95.7 parts deionized water (DIW), 1 part sodium salt of sulfonated diphenyl ether tetrapropylene derivative 2A1, 1 part polyoxyethylene polystyrene phenolic ether 710, 94 parts isooctyl acrylate (EHA), 7 parts hydroxyethyl acrylate, 8 parts β-acryloyloxypropionic acid, 175 parts butyl acrylate (BA), 131 parts ethyl acrylate (EA), 16 parts methacrylate (MAA), 4 parts acrylic acid (AA), and 140 parts styrene (ST) were prepared in pre-emulsification tank 1 and stirred thoroughly.

[0105] Pre-emulsion II preparation: 30 parts of finished seed emulsion, 1.0 part of n-dodecyl mercaptan (N-DM), 1.0 part of sodium bicarbonate, and 7 parts of deionized water are prepared in pre-emulsification tank 2 and stirred thoroughly.

[0106] Weigh 1.9 parts of ammonium persulfate (APS) and dissolve it in 10 parts of deionized water (DIW) to prepare the first oxidant solution; weigh 1.5 parts of ammonium persulfate (APS) and dissolve it in 38 parts of deionized water (DIW) to prepare the second oxidant solution.

[0107] Add 110 parts of deionized water to the reactor and heat to 80°C. Add 6.9 parts of sodium allyl ether hydroxypropyl sulfonate COPS-1, 4.5 parts of ethoxylated C12-14 alcohol AE-07, and 30 parts of the finished seed emulsion. Add the first oxidant solution to the reactor, and after 5 minutes, add the pre-emulsion I solution and the second oxidant solution dropwise, controlling the reaction temperature at 80°C. Simultaneously, add pre-emulsion II dropwise to pre-emulsion I until all the solution is added, with a dropwise addition time of 360 minutes. After holding at the temperature for 45 minutes, the material in the reactor was cooled to 70°C. 2 parts of tert-butyl hydroperoxide (TBHP) dissolved in 10 parts of deionized water (DIW) and 1.5 parts of isoascorbic acid (IAA) dissolved in 10 parts of deionized water (DIW) were added dropwise over 40 minutes. Then, at 70°C, 5 parts of sodium sulfate dissolved in 50 parts of water were added dropwise over 30 minutes. The temperature was then maintained for 10-20 minutes, followed by rapid cooling to 50°C over 25 minutes. Finally, 3.1 parts of MEA were added for neutralization, along with 0.4 parts of defoamer Tego-825 and 1.9 parts of preservative Kordek MLX, to obtain emulsion 1-2.

[0108] Example 3: Emulsion 1-3

[0109] Pre-emulsion I preparation: 95.7 parts deionized water (DIW), 1.5 parts sodium salt of sulfonated diphenyl ether tetrapropylene derivative 2A1, 1.5 parts polyoxyethylene polystyrene phenolic ether 710, 133 parts isooctyl acrylate (EHA), 8.5 parts hydroxyethyl acrylate, 1.5 parts β-acryloyloxypropionic acid, 175 parts butyl acrylate (BA), 205 parts ethyl acrylate (EA), 75 parts methacrylate (MAA), and 80 parts acrylate (AA) were prepared in pre-emulsification tank 1 and stirred thoroughly.

[0110] Pre-emulsion II preparation: 20 parts of finished seed emulsion, 1.3 parts of n-dodecyl mercaptan (N-DM), 1.3 parts of sodium bicarbonate (NaHCO3), and 7 parts of deionized water are prepared in pre-emulsification tank 2 and stirred thoroughly.

[0111] Weigh 1 part of ammonium persulfate (APS) and dissolve it in 10 parts of deionized water (DIW) to prepare the first oxidizing agent solution; weigh 1 part of ammonium persulfate (APS) and dissolve it in 38 parts of deionized water (DIW) to prepare the second oxidizing agent solution.

[0112] Add 110 parts of deionized water to the reactor and heat to 90°C. Add 1 part of sodium allyl ether hydroxypropyl sulfonate COPS-1, 7 parts of ethoxylated C12-14 alcohol AE-07, and 10 parts of the finished seed emulsion. Add the first oxidant solution to the reactor, and after 3 minutes, add the pre-emulsion I solution and the second oxidant solution dropwise, controlling the reaction temperature at 90°C. Simultaneously, add pre-emulsion II dropwise to pre-emulsion I until all the solution is added, with a dropwise addition time of 180 minutes. After holding at the temperature for 45 minutes, the material in the reactor was cooled to 65°C. Two parts of tert-butyl hydroperoxide (TBHP) dissolved in 10 parts of deionized water (DIW) and one part of isoascorbic acid (IAA) dissolved in 10 parts of deionized water (DIW) were added dropwise over 40 minutes. Then, at 65°C, seven parts of sodium sulfate dissolved in 50 parts of water were added dropwise over 30 minutes. The temperature was then maintained for 10-20 minutes until the particle size increased to 520 nm. The temperature was then rapidly reduced to 50°C over 18 minutes. Four parts of MEA were then added for neutralization, along with 0.4 parts of defoamer (Tego-825) and 1.4 parts of preservative (Kordek MLX), resulting in emulsion 1-3.

[0113] Example 4: Emulsion 1-4

[0114] Pre-emulsion I preparation: 95.7 parts deionized water (DIW), 3.3 parts sodium salt of sulfonated diphenyl ether tetrapropylene derivative 2A1, 3.7 parts polyoxyethylene polystyrene phenolic ether 710, 133 parts isooctyl acrylate (EHA), 12 parts hydroxyethyl acrylate, 12 parts β-acryloyloxypropionic acid, 175 parts butyl acrylate (BA), 195 parts ethyl acrylate (EA), 75 parts methacrylate (MAA), 45 parts acrylic acid (AA), and 20 parts styrene (ST) were prepared in pre-emulsification tank 1 and stirred thoroughly.

[0115] Pre-emulsion II preparation: 15 parts of finished seed emulsion, 1 part of n-dodecyl mercaptan (N-DM), 1.6 parts of sodium bicarbonate (NaHCO3), and 7 parts of deionized water are prepared in pre-emulsification vessel 2 and stirred thoroughly.

[0116] Weigh 1 part of ammonium persulfate (APS) and dissolve it in 10 parts of deionized water (DIW) to prepare the first oxidant solution; weigh 2.0 parts of ammonium persulfate (APS) and dissolve it in 38 parts of deionized water (DIW) to prepare the second oxidant solution.

[0117] Add 110 parts of deionized water to the reactor and heat to 85°C. Add 2 parts of sodium allyl ether hydroxypropyl sulfonate COPS-1, 9 parts of ethoxylated C12-14 alcohol AE-07, and 6 parts of the finished seed emulsion. Add the first oxidant solution to the reactor, and after 3 minutes, add the pre-emulsion I solution and the second oxidant solution dropwise, controlling the reaction temperature at 85°C. Simultaneously, add pre-emulsion II dropwise to pre-emulsion I until all the solution is added, with a dropwise addition time of 180 minutes. After maintaining the temperature for 45 minutes, the material in the reactor was cooled to 75°C. Two parts of tert-butyl hydroperoxide (TBHP) dissolved in 10 parts of deionized water (DIW) and 0.6 parts of isoascorbic acid (IAA) dissolved in 10 parts of deionized water (DIW) were added dropwise over 40 minutes. Then, at 75°C, 8 parts of sodium sulfate dissolved in 50 parts of water were added dropwise over 30 minutes. The temperature was then maintained for 10-20 minutes while monitoring the particle size. The temperature was then slowly lowered to 50°C over 60 minutes. Finally, 2.1 parts of MEA were added for neutralization, along with 0.4 parts of defoamer (Tego-825) and 1.5 parts of preservative (Kordek MLX). Emulsion 1-4 was obtained.

[0118] Example 5: Emulsion 1-5

[0119] Pre-emulsion I preparation: 95.7 parts deionized water (DIW), 1 part sodium salt of sulfonated diphenyl ether tetrapropylene derivative 2A1, 1 part polyoxyethylene polystyrene phenolic ether 710, 140 parts isooctyl acrylate (EHA), 7.5 parts hydroxyethyl acrylate, 7.5 parts β-acryloyloxypropionic acid, 175 parts butyl acrylate (BA), 146 parts ethyl acrylate (EA), 75 parts methacrylate (MAA), 50 parts acrylic acid (AA), and 25 parts styrene (ST) were prepared in pre-emulsification tank 1 and stirred thoroughly.

[0120] Pre-emulsion II preparation: 18 parts of finished seed emulsion, 0.8 parts of n-dodecyl mercaptan (N-DM), 1.5 parts of sodium bicarbonate (NaHCO3), and 7 parts of deionized water were prepared in pre-emulsification tank 2 and stirred thoroughly.

[0121] Weigh 2 parts of ammonium persulfate (APS) and dissolve it in 10 parts of deionized water (DIW) to prepare the first oxidant solution; weigh 2.0 parts of ammonium persulfate (APS) and dissolve it in 38 parts of deionized water (DIW) to prepare the second oxidant solution.

[0122] Add 110 parts of deionized water to the reactor and heat to 80°C. Add 1 part of sodium allyl ether hydroxypropyl sulfonate COPS-1, 12 parts of ethoxylated C12-14 alcohol AE-07, and 18 parts of the finished seed emulsion. Add the first oxidant solution to the reactor, and after 3 minutes, add the pre-emulsion I solution and the second oxidant solution dropwise, controlling the reaction temperature at 80°C. Simultaneously, add pre-emulsion II dropwise to pre-emulsion I until all the solution is added, with a dropwise addition time of 180 minutes. After holding at the temperature for 45 minutes, the material in the reactor was cooled to 65°C. Two parts of tert-butyl hydroperoxide (TBHP) dissolved in 10 parts of deionized water (DIW) and 0.8 parts of isoascorbic acid (IAA) dissolved in 10 parts of deionized water (DIW) were added dropwise over 40 minutes. Then, at 65°C, 7.5 parts of sodium sulfate dissolved in 50 parts of water were added dropwise over 30 minutes. The temperature was then maintained for 10-20 minutes while monitoring the particle size. The temperature was then rapidly lowered to 50°C over 17 minutes. Two parts of MEA were then added for neutralization, along with 0.4 parts of defoamer (Tego-825) and 1.6 parts of preservative (Kordek MLX). Emulsion 1-5 was obtained.

[0123] Example 6: Emulsion 1-6

[0124] Pre-emulsion I preparation: 95.7 parts deionized water (DIW), 1.5 parts sodium salt of sulfonated diphenyl ether tetrapropylene derivative 2A1, 1.5 parts polyoxyethylene polystyrene phenolic ether 710, 133 parts isooctyl acrylate (EHA), 15 parts hydroxyethyl acrylate, 15 parts β-acryloyloxypropionic acid, 175 parts butyl acrylate (BA), 125 parts ethyl acrylate (EA), 75 parts methacrylate (MAA), 45 parts acrylic acid (AA), and 30 parts styrene (ST) were prepared in pre-emulsification tank 1 and stirred thoroughly.

[0125] Pre-emulsion II preparation: 10 parts of finished seed emulsion, 0.6 parts of n-dodecyl mercaptan (N-DM), 0.6 parts of sodium bicarbonate (NaHCO3), and 7 parts of deionized water are prepared in pre-emulsification tank 2 and stirred thoroughly.

[0126] Weigh 1.7 parts of ammonium persulfate (APS) and dissolve it in 10 parts of deionized water (DIW) to prepare the first oxidant solution; weigh 1.7 parts of ammonium persulfate (APS) and dissolve it in 38 parts of deionized water (DIW) to prepare the second oxidant solution.

[0127] Add 110 parts of deionized water to the reactor and heat to 65°C. Add 1 part of sodium allyl ether hydroxypropyl sulfonate COPS-1, 3 parts of ethoxylated C12-14 alcohol AE-07, and 20 parts of the finished seed emulsion. Add the first oxidant solution to the reactor, and after 3 minutes, add the pre-emulsion I solution and the second oxidant solution dropwise, controlling the reaction temperature at 65°C. Simultaneously, add pre-emulsion II dropwise to pre-emulsion I until all the solution is added, with a dropwise addition time of 180 minutes. After holding at this temperature for 45 minutes, the material in the reactor was cooled to 55°C. Two parts of tert-butyl hydroperoxide (TBHP) dissolved in 10 parts of deionized water (DIW) and 1.4 parts of isoascorbic acid (IAA) dissolved in 10 parts of deionized water (DIW) were added dropwise over 40 minutes. Then, at 55°C, 6.3 parts of sodium sulfate dissolved in 50 parts of water were added dropwise over 30 minutes. The temperature was then maintained for 10-20 minutes while monitoring the particle size. The temperature was then rapidly lowered to 50°C over 28 minutes. Finally, one part of MEA was added for neutralization, along with 0.4 parts of defoamer (Tego-825) and one part of preservative (Kordek MLX). Emulsion 1-6 was obtained.

[0128] Comparative Example 1: Emulsion 2-1

[0129] Pre-emulsion preparation: 126 parts deionized water (DIW), 3.3 parts sodium salt of sulfonated diphenyl ether tetrapropylene derivative 2A1, 3.3 parts polyoxyethylene polystyrene phenolic ether 710, 275.3 parts isooctyl acrylate (EHA), 8.5 parts hydroxyethyl acrylate, 9.5 parts β-acryloyloxypropionic acid, 294.3 parts butyl acrylate, 49.8 parts methyl methacrylate (MMA), 15 parts methacrylate (MAA), and 1.3 parts n-dodecyl mercaptan (N-DM) were prepared in a pre-emulsion kettle and stirred thoroughly.

[0130] Weigh 0.9 parts of ammonium persulfate (APS) and dissolve it in 10 parts of deionized water (DIW) to prepare the first oxidant solution; weigh 2.0 parts of ammonium persulfate (APS) and dissolve it in 38 parts of deionized water (DIW) to prepare the second oxidant solution.

[0131] Add 125.6 parts of deionized water to the reactor and heat to 80-85℃. Add 4.3 parts of sodium allyl ether hydroxypropyl sulfonate (COPS-1), 0.4 parts of sodium bicarbonate (NaHCO3), and 39.4 parts of the finished seed emulsion. Add the first oxidant solution to the reactor, and after 3 minutes, add the pre-emulsion solution and the second oxidant solution dropwise, controlling the reaction temperature at 80-85℃. Continue this process until all the solutions are added, with a total addition time of 180 minutes. After maintaining the temperature for 45 minutes, cool the material in the reactor to 65-75℃. Add 1.4 parts of tert-butyl hydroperoxide (TBHP) dissolved in 10 parts of deionized water (DIW) and 0.8 parts of isoascorbic acid (IAA) dissolved in 10 parts of deionized water (DIW) dropwise over a period of 40 minutes. Cool to below 50°C, add 1.1 parts MEA for neutralization, 0.4 parts defoamer Tego-825 and 1.9 parts preservative Kordek MLX to obtain emulsion 2-1.

[0132] Comparative Example 2: Emulsion 2-2

[0133] Pre-emulsion preparation: 150 parts deionized water (DIW), 3.3 parts sodium salt of sulfonated diphenyl ether tetrapropylene derivative 2A1, 3.3 parts polyoxyethylene polystyrene phenolic ether 710, 200.3 parts isooctyl acrylate (EHA), 8.5 parts hydroxyethyl acrylate, 9.5 parts β-acryloyloxypropionic acid, 244.3 parts butyl acrylate, 99.8 parts methyl methacrylate (MMA), 75 parts styrene (ST), 15 parts methacrylate (MAA), and 1.3 parts n-dodecyl mercaptan (N-DM) were prepared in a pre-emulsion kettle and stirred thoroughly.

[0134] Weigh 0.9 parts of ammonium persulfate (APS) and dissolve it in 10 parts of deionized water (DIW) to prepare the first oxidant solution; weigh 2.0 parts of ammonium persulfate (APS) and dissolve it in 38 parts of deionized water (DIW) to prepare the second oxidant solution.

[0135] Add 125.6 parts of deionized water to the reactor and heat to 80-85℃. Add 4.3 parts of sodium allyl ether hydroxypropyl sulfonate (COPS-1), 0.4 parts of sodium bicarbonate (NaHCO3), and 39.4 parts of the finished seed emulsion. Add the first oxidant solution to the reactor, and after 3 minutes, add the pre-emulsion solution and the second oxidant solution dropwise, controlling the reaction temperature at 80-85℃. Continue this process until all the solutions are added, with a total addition time of 180 minutes. After maintaining the temperature for 45 minutes, cool the material in the reactor to 65-75℃. Add 1.4 parts of tert-butyl hydroperoxide (TBHP) dissolved in 10 parts of deionized water (DIW) and 0.8 parts of isoascorbic acid (IAA) dissolved in 10 parts of deionized water (DIW) dropwise over a period of 40 minutes. Cool to below 50°C, add 1.1 parts MEA for neutralization, 0.4 parts defoamer Tego-825 and 1.9 parts preservative Kordek MLX to obtain emulsion 2-1.

[0136] The contact adhesive latexes prepared in the above embodiments and comparative examples were tested according to the following standards:

[0137] Initial adhesion test standard: Select two sponges of the same size, apply the prepared emulsion to the cross-section of each sponge, and when the two sponges are put together, feel the force applied by hand, and divide it into three levels: light - A+++, medium - A++, heavy - A+. The lighter the force, the better the initial adhesion of the emulsion.

[0138] Wet adhesion test standard: Select two sponges of the same size, apply the prepared emulsion to the cross-section of both sponges, stick the two sponges together, and then immediately tear them apart. Observe the amount of adhesive residue on the sticking surfaces of the two sponges, and classify them into three levels: tearing material breakage - A+++, tearing with a large amount of adhesive residue on both sides - A++, tearing with adhesive residue on one side - A+. Tearing material breakage indicates that the emulsion has the best wet adhesion performance.

[0139] Cohesive strength test standard: Select a piece of sponge, apply the prepared emulsion to the cross-section, then fold it in half and stick it together. Dry it at 25℃ for 25 hours, and test the distance of separation after drying. The unit is mm. The smaller the distance, the better the cohesive strength.

[0140] Particle size: Determined using a Malvern ZS90 particle size analyzer, employing a polystyrene latex model, with water as the dispersion medium, and using general purpose analytical methods.

[0141] Process viscosity: measured using Brookfield LV63#30r and 64#60r.

[0142] Slag content: determined using a 325-mesh filter and analytical method WHPU / T011-685-2015.

[0143] Table 2 Experimental conditions for the examples and comparative examples

[0144] Experiment number condition Acid percentage Cooling time after adding inorganic salts AE07 content Example 1 Preferred Samples 20.8 20 1.2 Example 2 Acidity decreased 3.5 25 0.8 Example 3 Increased acidity 22.9 18 1 Example 4 The cooling time is extended 18 60 1.5 Example 5 AE07 quantity increased 20 17 1.9 Example 6 AE07 quantity decreased 19.6 28 0.5 Comparative Example 1 Conventional adhesive emulsions with low Tg 2.3 63 0 Comparative Example 2 High Tg of conventional adhesive emulsions 2.3 70 0

[0145] Table 3 Comparison of Emulsion Performance Tests

[0146]

[0147]

[0148] As can be seen from Table 3, the emulsion produced by this invention, through a special production process and ingenious overall formula design, exhibits stable polymerization during the polymerization stage compared to Comparative Examples 2-1 and 2-2. The residue content can be controlled within 100 ppm, meeting the requirements of industrialization. At the same time, the key bonding and wet adhesion properties are excellent, both reaching A+++ or above, and the cohesive performance is also outstanding. It balances the relationship between the production stability and performance of the product, with a comprehensive score of 10 points, completely solving the problem in this industry.

[0149] By examining the three key factors in Examples 1-6—acid content, cooling time after adding inorganic salts, and content of AE07 emulsifiers—it can be found that acid content and AE07 emulsifiers affect the residue content and key properties of the emulsion, while cooling time after adding inorganic salts mainly affects the residue content of the product. By optimizing the combination of these three key factors, the emulsion production can achieve better stability and superior performance.

[0150] Finally, it should be noted that the above examples of contact latex are only used to describe preferred embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that various modifications and improvements made to the technical solutions of the present invention by means of modifications or equivalent substitutions should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A water-based acrylic contact latex, characterized in that, Components comprising the following parts by weight: 140-160 parts by weight of hard monomer; Soft monomer 400-550 parts by weight; 10-30 parts by weight of functional monomer; 20-60 parts by weight of finished seed emulsion; Emulsifier 5-20 parts by weight; Pre-emulsion additive 0.6-3 parts by weight; Oxidizing agent 2-8 parts by weight; Reducing agent 0.4-2 parts by weight; 5-10 parts by weight of inorganic salt; Add 1.6-7 parts by weight of auxiliary agent later; 260-340 parts by weight of water; The method for preparing the aqueous acrylic contact adhesive latex includes the following steps: (1) Add water to the reactor and heat it to 65-95℃. Add emulsifier and finished seed emulsion to the bottom of the reactor. (2) At 65-95℃, add the first oxidant to the reactor, add pre-emulsion I and the second oxidant dropwise to the reactor, and at the same time add pre-emulsion II dropwise to pre-emulsion I until all the pre-emulsion has been added. (3) Keep warm for 30-60 minutes, cool down to 55-75℃, and simultaneously add optional post-treatment oxidant and reducing agent. Then continue to add inorganic salt solution. After the addition is completed, keep warm. During the warming process, test the particle size of the product. When the particle size reaches 400-430nm, then quickly cool down to below 50℃. The cooling time should be ≤30 minutes. Then add the post-additional additives, adjust the pH to 3.0-6.5, and filter out the material. The preemulsion I comprises the following components, based on the total mass of preemulsion I: Hard monomer 140-160 parts by weight; Soft monomer 400-550 parts by weight; 10-30 parts by weight of functional monomer; Emulsifier 4-10 parts by weight; 90-110 parts by weight of water; The preemulsion II comprises the following components, based on the total mass of preemulsion II: 10-35 parts by weight of finished seed emulsion; Pre-emulsion additive 0.6-3 parts by weight; 5-15 parts by weight of water; The hard monomer is selected from any one or more combinations of butyl methacrylate, acrylamide, methyl methacrylate, styrene, acrylic acid, and methacrylic acid; wherein acid monomers account for 18-21% of the total monomer weight; The emulsifier is any one or a combination of COPS-1, sodium tridecyl alcohol polyoxyethylene ether sulfate, AE-07, AE-09, sodium salt of sulfonated diphenyl ether tetrapropylene derivative, polyoxyethylene polystyrene phenolic ether, sodium allyl ether hydroxypropyl sulfonate, and sodium dodecyl sulfate; AE-07 and AE-09 type emulsifiers account for 0.8-1.5% of the total monomer weight.

2. The aqueous acrylic contact latex according to claim 1, characterized in that, Components comprising the following parts by weight: Hard monomer 145-155 parts by weight; 430-500 parts by weight of soft monomer; 15-25 parts by weight of functional monomer; 30-50 parts by weight of finished seed emulsion; Emulsifier 7-18 parts by weight; Pre-emulsion additive: 0.9-2.6 parts by weight; 3-7 parts by weight of oxidant; 0.5-1.5 parts by weight of reducing agent; 6-8 parts by weight of inorganic salt; Add 2.4-5.8 parts by weight of auxiliary agent later; 270-330 parts by weight of water.

3. The aqueous acrylic contact latex according to claim 1 or 2, characterized in that, The water-based acrylic contact latex has a solid content of 65wt%-67wt% and a particle size of 300-500nm.

4. The aqueous acrylic contact latex according to claim 1 or 2, characterized in that, The hard monomer is selected from a combination of acidic monomers containing acrylic acid and / or methacrylic acid.

5. The aqueous acrylic contact latex according to claim 1 or 2, characterized in that, The soft monomer is selected from any one or more of allyl methacrylate, isooctyl acrylate, butyl acrylate, and ethyl acrylate.

6. The aqueous acrylic contact latex according to claim 1 or 2, characterized in that, The functional monomer is selected from one or two of diacetone acrylamide, hydroxyethyl methacrylate, hydroxyethyl acrylate, and β-acryloyloxypropionic acid.

7. The aqueous acrylic contact latex according to claim 1 or 2, characterized in that, The finished seed emulsion is a commercially available water-based acrylic emulsion with a particle size of 60-120 nm and a solid content of 42-43%.

8. The aqueous acrylic contact latex according to claim 7, characterized in that, The particle size of the finished seed emulsion is 90-120 nm.

9. The aqueous acrylic contact latex according to claim 1 or 2, characterized in that, The emulsifier is selected from a combination containing AE-07 and / or AE-09.

10. The aqueous acrylic contact latex according to claim 1 or 2, characterized in that, The pre-emulsion additives include at least one of chain transfer agents and buffers.

11. The aqueous acrylic contact latex according to claim 10, characterized in that, The chain transfer agent is any one of n-dodecyl mercaptobutyl ester and the buffer is any one of sodium bicarbonate, sodium carbonate, and ammonia.

12. The aqueous acrylic contact latex according to claim 1 or 2, characterized in that, The oxidant is one or more of ammonium persulfate, sodium persulfate, tert-butyl hydroperoxide, and hydrogen peroxide.

13. The aqueous acrylic contact latex according to claim 12, characterized in that, The reducing agent is one or more of sodium metabisulfite, isoascorbic acid, sodium hydrosulfite, sodium formaldehyde sulfoxylate, and FF6.

14. The aqueous acrylic contact latex according to claim 12, characterized in that, The inorganic salt is one or more of sodium sulfate, potassium sulfate, ammonium sulfate, sodium carbonate, and sodium bicarbonate.

15. The aqueous acrylic contact latex according to claim 12, characterized in that, The added additives include at least one of the neutralizing agents, defoamers, and preservatives commonly used in emulsion polymerization.

16. The aqueous acrylic contact latex according to claim 1 or 2, characterized in that, The method for preparing the aqueous acrylic contact adhesive latex includes the following steps: (1) Add water to the reactor and heat it to 65-95℃. Add emulsifier and finished seed emulsion to the bottom of the reactor. (2) At 65-95℃, add the first oxidant to the reactor. After 1-15 min, add pre-emulsion I and the second oxidant to the reactor. At the same time, add pre-emulsion II to pre-emulsion I until all the pre-emulsions are added. The total time for adding is 180-360 min. (3) Keep warm for 30-60 minutes, cool down to 55-75℃, and simultaneously add optional post-treatment oxidant and reducing agent for 30-60 minutes. Then continue to add inorganic salt solution for 20-40 minutes. After the addition is completed, keep warm. During the warming process, test the particle size of the product. When the particle size reaches 400-430nm, then quickly cool down to below 50℃. The cooling time should be ≤30 minutes. Then add the post-additional additives, adjust the pH to 3.0-6.5, and filter out the material.

17. The aqueous acrylic contact latex according to claim 1 or 2, characterized in that, The preemulsion I comprises the following components, based on the total mass of preemulsion I: Hard monomer 145-155 parts by weight; 430-500 parts by weight of soft monomer; 15-25 parts by weight of functional monomer; 5-10 parts by weight of emulsifier; 95-105 parts by weight of water.

18. The aqueous acrylic contact latex according to claim 17, characterized in that, The preemulsion II comprises the following components, based on the total mass of preemulsion II: 25-30 parts by weight of finished seed emulsion; Pre-emulsion additive: 0.9-2.6 parts by weight; 5-10 parts by weight of water.

19. The use of the aqueous acrylic contact adhesive emulsion according to any one of claims 1 to 18 in contact adhesives.

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