A kind of carboxylated styrene butadiene latex production process and equipment

Abstract

The invention discloses a carboxylated styrene butadiene latex production process and equipment thereof. The production process comprises the preparation of acrylonitrile, butadiene, soap solution, mercaptan, initiator and the like, as well as reaction, degassing, blending, filtering and obtaining a finished carboxylated styrene butadiene latex. The surface strength and bonding strength of the carboxylated styrene butadiene latex are improved by adding acrylonitrile, the chemical stability and anti-foaming property of the carboxylated styrene butadiene latex are improved by adding functional monomers, and the reaction of the entire system is relatively complete by sequentially adding raw materials and stirring while adding the materials, thereby effectively improving the conversion rate. The production equipment comprises an acrylonitrile metering tank, a butadiene metering tank, a soap preparation kettle, a reaction kettle, a degassing kettle, a blending kettle and the like. The carboxylated styrene butadiene latex obtained by the invention has excellent properties, can impart excellent properties to paper, and improve the smoothness and glossiness of the paper.

Description

Technical Field

[0001] The invention relates to the technical field of latex production, in particular to a carboxylated styrene-butadiene latex production process and equipment thereof. Background Art

[0002] With the rapid development of my country's socioeconomic landscape, per capita paper consumption is increasing, and the demand for paper quality is also rising. Surface coating is a key approach to improving paper quality. With the increasing demand for high-end packaging, coated paper is poised to become a future trend. During the production of coated paper, high coating performance requirements are imposed, including excellent rheological properties and a high solids content to minimize drying costs. To achieve these coating requirements, the properties of the latex are crucial. The latex must possess excellent bonding strength to enhance the surface strength of the coated paper, and good leveling properties after coating to improve the gloss of the coated paper surface.

[0003] Carboxylated styrene butadiene latex (CSB) is currently the most widely used latex in coated paper production. However, most of the CSB latex for papermaking currently sold on the market cannot meet the needs of specific applications due to differences in preparation methods. The resulting CSB latex also fails to provide a balance of stability, bonding strength, wet glue surface strength, and anti-foaming properties. The gloss and smoothness of the coated paper are also insufficient. Summary of the Invention

[0004] In order to solve the above-mentioned technical problems, the present invention provides a carboxylated styrene butadiene latex production process and equipment thereof.

[0005] The technical solution of the present invention is achieved as follows:

[0006] A process for producing carboxylated styrene-butadiene latex comprises the following steps:

[0007] S1. Use a pump to pump acrylonitrile into an acrylonitrile metering tank for use, and pump butadiene into a butadiene metering tank for use;

[0008] S2. Use the liquid level difference to put soft water into the soap kettle, start stirring, and while stirring, sequentially add the emulsifier, chelating agent, mixing monomer, and sodium bicarbonate to the soap kettle. Heat to 50 ° C and keep warm for 30 minutes to make soap solution. Stop stirring and set aside.

[0009] S3. The initiator and soft water are added to the initiator preparation tank and stirred until dissolved, the vacuum is turned on and sucked into the initiator addition tank for use;

[0010] S4. Using the liquid level difference, soft water was added to the reactor, the reactor vacuum was turned on, the soap solution, mercaptan, and acrylonitrile were configured and pumped into the reactor, replaced with nitrogen twice, and the vacuum was continued to 0.06MPa, and the butadiene and functional monomers were injected into the reactor;

[0011] S5. When the reactor steam temperature rises to 40°C, the initiator in the initiator feeding tank is added, and when the temperature rises, the jacket is kept at a constant temperature with ice water;

[0012] S6. Control the temperature until the reaction is completed when the conversion rate is greater than 98%;

[0013] S7. The reaction latex obtained by steam was pressed into a degassing vessel, the degassing vessel was opened, stirred and evacuated through the condenser, the sodium thiamethoxam, aqueous antioxidant was sequentially drawn into the degassing vessel, and the evacuation was continued. The temperature was raised to 70 ° C with steam, and the temperature was maintained and the tumbling state was controlled to control the negative pressure of 0.06MPa to 0.08MPa.

[0014] After S8.60min, close the steam and vacuum valves, cool to below 50℃ and discharge the material into the blending kettle;

[0015] S9. Open the blending kettle and stir, slowly add liquid caustic soda to adjust the pH to 8.5 over 30 minutes, and continue stirring for 30 minutes;

[0016] S10. Filter the mixture through a 200-mesh filter through a vibrating screen into a turnover tank and press it into a finished product tank to obtain carboxylated styrene-butadiene latex. The raw material ratio is based on the total weight of the composition, and all raw materials are calculated in parts by weight as follows:

[0017]

[0018] The emulsifier is composed of an anionic emulsifier and a nonionic emulsifier in a mass ratio of 3:1. The anionic emulsifier is one or more of C8-C18 alkylbenzene sulfonate, C8-C18 alkyl sulfate, and C8-C18 alkyldiphenol ether disulfonate, preferably sodium lauryl sulfate. The nonionic emulsifier is one or more of C8-C12 alkylphenol polyoxyethylene ether with an ethylene oxide addition number of 5-20, C8-C12 fatty alcohol polyoxyethylene ether with an ethylene oxide addition number of 5-20, and C4-C8 fatty alcohol polyoxypropylene ether with a propylene oxide addition number of 2-10, preferably NP-10.

[0019] The chelating agent is a metal ion chelating agent, including one or more of disodium edetate, tetrasodium edetate and sodium tripolyphosphate.

[0020] The mixed monomers include 86.5-88.5% styrene and 11.5-14.0% methacrylic acid in percentage by mass. The initiator includes one or more of potassium persulfate, ammonium persulfate, and hydrogen peroxide, preferably potassium persulfate.

[0021] The mercaptan is an alkyl mercaptan, including one of ethanedithiol, ethyl mercaptan, dialkyl mercaptan, and tert-dodecyl mercaptan, preferably tert-dodecyl mercaptan.

[0022] The functional monomer includes one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl acrylate.

[0023] Disclosed is a carboxylated styrene butadiene latex production device, comprising an acrylonitrile metering tank, a butadiene metering tank, a soap preparation kettle, and an initiator preparation tank. The acrylonitrile metering tank is connected to a reactor via a pump, the butadiene metering tank is connected to the reactor via a pump, the soap preparation kettle is connected to the reactor via a pump, the initiator preparation tank is connected to an initiator feeding tank via a pump, a degassing kettle is connected below the reactor, the degassing kettle is connected to a condenser via a valve, a blending kettle is connected below the degassing kettle, a filter is connected below the blending kettle, a turnover tank is connected below the filter, and a finished product tank is connected below the turnover tank. The present invention solves the problem that carboxylated styrene-butadiene latex cannot achieve stability, bonding strength, wet glue surface strength and anti-foaming performance. By pumping various ingredients directly into a polymerization kettle in sequence, stirring them simultaneously during the introduction process, the ingredients are mixed more evenly, further avoiding the phenomenon of incomplete polymerization reaction of raw materials, thereby further ensuring the stability of product performance. By introducing a large number of water molecules, hydroxyl groups can be stably present without esterification reaction with carboxyl groups. By introducing acrylonitrile, condensation reaction occurs between groups such as carboxyl groups, hydroxyl groups, and nitrile groups to form cross-linked bonds to form cross-linked polymers, and linear emulsion polymers are cross-linked to produce a three-dimensional network structure, thereby improving the surface strength, wear resistance, bonding strength, water washability, alkali resistance, antifouling and other properties of the polymer. Since the glass transition temperature of acrylonitrile is relatively high, the glass transition temperature of the latex is also increased, reducing the latex polymer. The interaction force between the coating and the printing ink, so the carboxylated styrene butadiene latex with added acrylonitrile can not only improve the printability of the coated paper, but also improve the gloss and smoothness of the coated paper. By adopting the emulsion polymerization technology, the unsaturated double bonds and hydroxyl groups in the functional monomers are copolymerized with the unsaturated double bonds of other raw materials such as butadiene, and hydroxyl groups are introduced into the styrene butadiene molecular chain, so that the surface of the carboxylated styrene butadiene particles has a certain number of non-ionic polar groups. The groups have a certain self-emulsification effect, and the interaction force between the polar groups is strong. Therefore, it not only improves the chemical stability, deformation resistance, adhesion, tensile strength and foaming resistance of the coated paper, but also effectively reduces the amount of emulsifier and reduces costs. By adding alkaline substances such as sodium bicarbonate and liquid alkali, the pH value of the system is adjusted to 8-10, thereby stabilizing the agglomeration process and improving production efficiency by shortening the reaction time. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a process flow chart of a carboxylated styrene-butadiene latex production process.

[0025] Figure 2 The present invention is a flow chart of a carboxylated styrene butadiene latex production device.

[0026] 1-Acrylonitrile metering tank; 2-Butadiene metering tank; 3-Soap preparation kettle; 4-Initiator preparation tank; 5-Initiator feeding tank; 6-Condenser; 7-Valve; 8-Finished product tank; 9-Turnover tank; 10-Filter; 11-Blending kettle; 12-Degassing kettle; 13-Reactor kettle; 14-Pump. DETAILED DESCRIPTION

[0027] The present invention provides a carboxylated styrene butadiene latex production process and equipment thereof. To deepen the understanding of the present invention, the present invention will be further described in detail below with reference to an embodiment. The present invention can be implemented in the following manner:

[0028] A process for producing carboxylated styrene-butadiene latex comprises the following steps:

[0029] S1. In parts by weight, 7.8 to 12.3 parts of acrylonitrile are pumped into an acrylonitrile measuring tank for use, and 45.0 to 52.6 parts of butadiene are pumped into a butadiene measuring tank for use;

[0030] S2. Using the liquid level difference, 76.7 to 88.3 parts of soft water are put into the soap making kettle, stirring is started, and 14.2 to 17.3 parts of emulsifier, 0.2 to 0.5 parts of chelating agent, 56.1 to 61.4 parts of mixed monomer, and 3.0 to 5.0 parts of sodium bicarbonate are sequentially added to the soap making kettle while stirring. The temperature is raised to 50°C and kept warm for 30 minutes to form a soap solution. Stirring is stopped and set aside. By pumping various ingredients directly into the polymerization kettle in sequence, stirring simultaneously during the introduction process, the ingredients are mixed more evenly, further avoiding the phenomenon of incomplete polymerization reaction of the raw materials, thereby further ensuring the stability of product performance;

[0031] S3. 6.4 to 8.7 parts of initiator and 18.2 to 23.4 parts of soft water are added to the initiator preparation tank and stirred until dissolved. The vacuum is turned on and sucked into the initiator addition tank for use. The vacuum is to remove the residual air in the kettle and facilitate feeding.

[0032] S4. Using the liquid level difference, 64.2 to 73.7 parts of soft water are added to the reactor. The vacuum of the reactor is turned on, and the prepared soap solution, 2.2 to 4.8 parts of mercaptan, and 7.8 to 12.3 parts of acrylonitrile are pumped into the reactor. The reactor is replaced with nitrogen twice and the vacuum is continued to be evacuated to 0.06 MPa. 45.0 to 52.6 parts of butadiene and 6.5 to 9.8 parts of functional monomers are injected into the reactor. By introducing a large amount of water molecules, the hydroxyl groups can be stably present without undergoing esterification reaction with the carboxyl groups. By introducing acrylonitrile, condensation reactions occur between groups such as carboxyl groups, hydroxyl groups, and nitrile groups to form cross-linked bonds to form cross-linked polymers. The linear emulsion polymer is cross-linked to produce a three-dimensional network structure, thereby improving the surface strength, abrasion resistance, bonding strength, water resistance, alkali resistance, and stain resistance of the polymer. Since the glass transition temperature of acrylonitrile is relatively high, the glass transition temperature of the latex is also increased, thereby reducing the interaction between the latex polymer coating and the printing ink.

[0033] S5. When the reactor steam temperature rises to 40°C, the initiator in the initiator feeding tank is added, and when the temperature rises, the jacket is kept at a constant temperature with ice water;

[0034] S6. Control the temperature until the reaction is completed when the conversion rate is greater than 98%;

[0035] S7. The reaction latex obtained by steam was pressed into a degassing kettle, the degassing kettle was opened, stirred and evacuated through the condenser, 2.4 to 3.6 parts of sodium thiamethoxam, 1.5 to 2.8 parts of an aqueous antioxidant were sequentially drawn into the degassing kettle, and vacuum was continued. The temperature was raised to 70 ° C. with steam, and the temperature and tumbling state were maintained. The negative pressure was controlled at 0.06 MPa to 0.08 MPa. The degassing process is to remove the residual monomers that have not been completely reacted in the reaction system, such as butadiene, styrene, and methacrylic acid, thereby reducing the concentration and odor of free monomers in the latex;

[0036] After S8.60min, close the steam and vacuum valves, cool to below 50℃ and discharge the material into the blending kettle;

[0037] S9. Open the blending kettle and stir, slowly add liquid caustic soda to adjust the pH to 8.5 over 30 minutes, and continue stirring for 30 minutes;

[0038] S10. Filter the mixture through a vibrating screen with a 200-mesh filter into a turnover tank and press it into a finished product tank to obtain carboxylated styrene-butadiene rubber latex. The emulsifier is composed of an anionic emulsifier and a nonionic emulsifier in a mass ratio of 3:1, i.e., 10.7-13.0 parts of anionic emulsifier and 3.6-4.3 parts of nonionic emulsifier, the anionic emulsifier being one or more of sodium C8-C18 alkylbenzenesulfonate, sodium C8-C18 alkyl sulfate, and sodium C8-C18 alkyldiphenol ether disulfonate, preferably sodium lauryl sulfate, and the nonionic emulsifier being one or more of C8-C12 alkylphenol polyoxyethylene ether with an ethylene oxide addition number of 5-20, C8-C12 fatty alcohol polyoxyethylene ether with an ethylene oxide addition number of 5-20, and C4-C8 fatty alcohol polyoxypropylene ether with a propylene oxide addition number of 2-10, preferably NP-10.

[0039] The chelating agent is a metal ion chelating agent, including one or more of disodium edetate, tetrasodium edetate and sodium tripolyphosphate.

[0040] The mixed monomers include 86.5-88.5% styrene and 11.5-14.0% methacrylic acid in percentage by mass. The initiator includes one or more of potassium persulfate, ammonium persulfate, and hydrogen peroxide, preferably potassium persulfate.

[0041] The mercaptan is an alkyl mercaptan, including one of ethanedithiol, ethyl mercaptan, dialkyl mercaptan, and tert-dodecyl mercaptan, preferably tert-dodecyl mercaptan.

[0042] The functional monomers include one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl acrylate. The unsaturated double bonds and hydroxyl groups in the functional monomers are copolymerized with the unsaturated double bonds of other raw materials such as butadiene, and hydroxyl groups are introduced into the butadiene styrene molecular chain, so that the surface of the carboxyl butadiene styrene particles carries a certain number of non-ionic polar groups, which have a certain self-emulsification effect, and the interaction between the polar groups is strong.

[0043] Disclosed is a carboxylated styrene butadiene latex production device, comprising an acrylonitrile metering tank, a butadiene metering tank, a soap preparation kettle, and an initiator preparation tank. The acrylonitrile metering tank is connected to a reactor via a pump, the butadiene metering tank is connected to the reactor via a pump, the soap preparation kettle is connected to the reactor via a pump, the initiator preparation tank is connected to an initiator feeding tank via a pump, a degassing kettle is connected below the reactor, the degassing kettle is connected to a condenser via a valve, a blending kettle is connected below the degassing kettle, a filter is connected below the blending kettle, a turnover tank is connected below the filter, and a finished product tank is connected below the turnover tank.

[0044] Example 1

[0045] This embodiment has less consumables and lower costs.

[0046] A process for producing carboxylated styrene-butadiene latex comprises the following steps:

[0047] S1. In parts by weight, 7.8 parts of acrylonitrile were pumped into the acrylonitrile measuring tank for use, and 48.0 parts of butadiene were pumped into the butadiene measuring tank for use;

[0048] S2. Using the liquid level difference, 76.7 parts of soft water were added to the soap kettle. Stirring was started, and while stirring, 11.7 parts of sodium lauryl sulfate and 3.9 parts of NP-10 composite emulsifier, 0.3 parts of tetrasodium ethylenediaminetetraacetate, 52.2 parts of styrene, 7.6 parts of methacrylic acid, and 4.2 parts of sodium bicarbonate were added to the soap kettle. The temperature was raised to 50°C and kept warm for 30 minutes to prepare the soap solution. Stirring was stopped and set aside.

[0049] S3 7.4 parts of potassium persulfate and 18.2 parts of soft water were added to the initiator preparation tank and stirred until dissolved, open the vacuum and suck it into the initiator addition tank for use;

[0050] S4. Using the liquid level difference, 64.2 parts of soft water were added to the reactor, the reactor vacuum was turned on, the configured soap solution, 2.8 parts of tert-dodecyl mercaptan, 7.8 parts of acrylonitrile were pumped into the reactor, replaced with nitrogen twice, and the vacuum was continued to 0.06 MPa, 48.0 parts of butadiene and 6.5 parts of hydroxyethyl methacrylate were injected into the reactor;

[0051] S5. When the reactor steam temperature rises to 40°C, the initiator in the initiator feeding tank is added, and when the temperature rises, the jacket is kept at a constant temperature with ice water;

[0052] S6. Control the temperature until the reaction is completed when the conversion rate is greater than 98%;

[0053] S7. The reaction latex obtained was pressed into a degassing vessel with steam, the degassing vessel was opened, stirred and evacuated through the condenser, 2.9 parts of sodium thiamin, 2.1 parts of an aqueous antioxidant were sequentially drawn into the degassing vessel, the evacuation was continued, and the temperature was raised to 70 ° C with steam, the temperature was maintained and the tumbling state was maintained, and the negative pressure was controlled at 0.06MPa to 0.08MPa;

[0054] After S8.60min, close the steam and vacuum valves, cool to below 50℃ and discharge the material into the blending kettle;

[0055] S9. Open the blending kettle and stir, slowly add liquid caustic soda to adjust the pH to 8.5 over 30 minutes, and continue stirring for 30 minutes;

[0056] S10. Filter the mixture through a 200-mesh filter through a vibrating screen into a turnover tank, and press the mixture into a finished product tank to obtain carboxylated styrene-butadiene rubber latex.

[0057] Example 2

[0058] This embodiment increases the proportion of acrylonitrile on the basis of Example 1, aiming to improve the surface strength and bonding strength of the carboxylated styrene-butadiene latex.

[0059] A process for producing carboxylated styrene-butadiene latex comprises the following steps:

[0060] S1. In parts by weight, 11.6 parts of acrylonitrile were pumped into an acrylonitrile measuring tank for use, and 48.0 parts of butadiene were pumped into a butadiene measuring tank for use;

[0061] S2. Using the liquid level difference, 76.7 parts of soft water were added to the soap kettle. Stirring was started, and while stirring, 11.7 parts of sodium lauryl sulfate and 3.9 parts of NP-10 composite emulsifier, 0.3 parts of tetrasodium ethylenediaminetetraacetate, 52.2 parts of styrene, 7.6 parts of methacrylic acid, and 4.2 parts of sodium bicarbonate were added to the soap kettle. The temperature was raised to 50°C and kept warm for 30 minutes to prepare the soap solution. Stirring was stopped and set aside.

[0062] S3 7.4 parts of potassium persulfate and 18.2 parts of soft water were added to the initiator preparation tank and stirred until dissolved, open the vacuum and suck it into the initiator addition tank for use;

[0063] S4. Using the liquid level difference, 64.2 parts of soft water were added to the reactor, the reactor vacuum was turned on, the prepared soap solution, 2.8 parts of tert-dodecyl mercaptan, 11.6 parts of acrylonitrile were pumped into the reactor, replaced with nitrogen twice, and the vacuum was continued to 0.06 MPa. 48.0 parts of butadiene and 6.5 parts of hydroxyethyl methacrylate were injected into the reactor;

[0064] S5. When the reactor steam temperature rises to 40°C, the initiator in the initiator feeding tank is added, and when the temperature rises, the jacket is kept at a constant temperature with ice water;

[0065] S6. Control the temperature until the reaction is completed when the conversion rate is greater than 98%;

[0066] S7. The reaction latex obtained was pressed into a degassing vessel with steam, the degassing vessel was opened, stirred and evacuated through the condenser, 2.9 parts of sodium thiamin, 2.1 parts of an aqueous antioxidant were sequentially drawn into the degassing vessel, the evacuation was continued, and the temperature was raised to 70 ° C with steam, the temperature was maintained and the tumbling state was maintained, and the negative pressure was controlled at 0.06MPa to 0.08MPa;

[0067] After S8.60min, close the steam and vacuum valves, cool to below 50℃ and discharge the material into the blending kettle;

[0068] S9. Open the blending kettle and stir, slowly add liquid caustic soda to adjust the pH to 8.5 over 30 minutes, and continue stirring for 30 minutes;

[0069] S10. Filter the mixture through a 200-mesh filter through a vibrating screen into a turnover tank, and press the mixture into a finished product tank to obtain carboxylated styrene-butadiene rubber latex.

[0070] Example 3

[0071] This embodiment increases the proportion of functional monomers on the basis of Example 2, aiming to improve the chemical stability and anti-foaming property of carboxylated styrene-butadiene latex.

[0072] A process for producing carboxylated styrene-butadiene latex comprises the following steps:

[0073] S1. In parts by weight, 11.6 parts of acrylonitrile were pumped into an acrylonitrile measuring tank for use, and 48.0 parts of butadiene were pumped into a butadiene measuring tank for use;

[0074] S2. Using the liquid level difference, 76.7 parts of soft water were added to the soap kettle. Stirring was started, and while stirring, 11.7 parts of sodium lauryl sulfate and 3.9 parts of NP-10 composite emulsifier, 0.3 parts of tetrasodium ethylenediaminetetraacetate, 52.2 parts of styrene, 7.6 parts of methacrylic acid, and 4.2 parts of sodium bicarbonate were added to the soap kettle. The temperature was raised to 50°C and kept warm for 30 minutes to prepare the soap solution. Stirring was stopped and set aside.

[0075] S3 7.4 parts of potassium persulfate and 18.2 parts of soft water were added to the initiator preparation tank and stirred until dissolved, open the vacuum and suck it into the initiator addition tank for use;

[0076] S4. Using the liquid level difference, 64.2 parts of soft water were added to the reactor, the reactor vacuum was turned on, the prepared soap solution, 2.8 parts of tert-dodecyl mercaptan, 11.6 parts of acrylonitrile were pumped into the reactor, replaced with nitrogen twice, and the vacuum was continued to 0.06 MPa. 48.0 parts of butadiene and 9.3 parts of hydroxyethyl methacrylate were injected into the reactor;

[0077] S5. When the reactor steam temperature rises to 40°C, the initiator in the initiator feeding tank is added, and when the temperature rises, the jacket is kept at a constant temperature with ice water;

[0078] S6. Control the temperature until the reaction is completed when the conversion rate is greater than 98%;

[0079] S7. The reaction latex obtained was pressed into a degassing vessel with steam, the degassing vessel was opened, stirred and evacuated through the condenser, 2.9 parts of sodium thiamin, 2.1 parts of an aqueous antioxidant were sequentially drawn into the degassing vessel, the evacuation was continued, and the temperature was raised to 70 ° C with steam, the temperature was maintained and the tumbling state was maintained, and the negative pressure was controlled at 0.06MPa to 0.08MPa;

[0080] After S8.60min, close the steam and vacuum valves, cool to below 50℃ and discharge the material into the blending kettle;

[0081] S9. Open the blending kettle and stir, slowly add liquid caustic soda to adjust the pH to 8.5 over 30 minutes, and continue stirring for 30 minutes;

[0082] S10. Filter the mixture through a 200-mesh filter through a vibrating screen into a turnover tank, and press the mixture into a finished product tank to obtain carboxylated styrene-butadiene rubber latex.

[0083] Example 4

[0084] This embodiment increases the proportion of soft water on the basis of embodiment 3, in order to stabilize the hydroxyl groups and reduce the probability of esterification reaction. A process for producing carboxylated styrene-butadiene latex comprises the following steps:

[0085] S1. In parts by weight, 11.6 parts of acrylonitrile were pumped into an acrylonitrile measuring tank for use, and 48.0 parts of butadiene were pumped into a butadiene measuring tank for use;

[0086] S2. Using the liquid level difference, 85.3 parts of soft water were added to the soap kettle. Stirring was started. While stirring, 11.7 parts of sodium lauryl sulfate and 3.9 parts of NP-10 composite emulsifier, 0.3 parts of tetrasodium ethylenediaminetetraacetate, 52.2 parts of styrene, 7.6 parts of methacrylic acid, and 4.2 parts of sodium bicarbonate were added to the soap kettle. The temperature was raised to 50°C and kept warm for 30 minutes to prepare the soap solution. Stirring was stopped and set aside.

[0087] S3. 7.4 parts of potassium persulfate and 21.5 parts of soft water were added to the initiator preparation tank and stirred until dissolved, the vacuum was turned on and sucked into the initiator addition tank for use;

[0088] S4. Using the liquid level difference, 71.8 parts of soft water were added to the reactor, the reactor vacuum was turned on, the prepared soap solution, 2.8 parts of tert-dodecyl mercaptan, 11.6 parts of acrylonitrile were pumped into the reactor, replaced with nitrogen twice, and the vacuum was continued to 0.06 MPa. 48.0 parts of butadiene and 9.3 parts of hydroxyethyl methacrylate were injected into the reactor;

[0089] S5. When the reactor steam temperature rises to 40°C, the initiator in the initiator feeding tank is added, and when the temperature rises, the jacket is kept at a constant temperature with ice water;

[0090] S6. Control the temperature until the reaction is completed when the conversion rate is greater than 98%;

[0091] S7. The reaction latex obtained was pressed into a degassing vessel with steam, the degassing vessel was opened, stirred and evacuated through the condenser, 2.9 parts of sodium thiamin, 2.1 parts of an aqueous antioxidant were sequentially drawn into the degassing vessel, the evacuation was continued, and the temperature was raised to 70 ° C with steam, the temperature was maintained and the tumbling state was maintained, and the negative pressure was controlled at 0.06MPa to 0.08MPa;

[0092] After S8.60min, close the steam and vacuum valves, cool to below 50℃ and discharge the material into the blending kettle;

[0093] S9. Open the blending kettle and stir, slowly add liquid caustic soda to adjust the pH to 8.5 over 30 minutes, and continue stirring for 30 minutes;

[0094] S10. Filter the mixture through a 200-mesh filter through a vibrating screen into a turnover tank, and press the mixture into a finished product tank to obtain carboxylated styrene-butadiene rubber latex.

[0095] Example 5

[0096] This embodiment simplifies the process steps based on embodiment 4 and saves time.

[0097] A process for producing carboxylated styrene-butadiene latex comprises the following steps:

[0098] S1. In parts by weight, 11.6 parts of acrylonitrile were pumped into an acrylonitrile measuring tank for use, and 48.0 parts of butadiene were pumped into a butadiene measuring tank for use;

[0099] S2. Using the liquid level difference, 85.3 parts of soft water were added to the soap making kettle. An emulsifier composed of 11.7 parts of sodium lauryl sulfate and 3.9 parts of NP-10, 0.3 parts of tetrasodium ethylenediaminetetraacetate, 52.2 parts of styrene, 7.6 parts of methacrylic acid, and 4.2 parts of sodium bicarbonate were added to the soap making kettle. Stirring was started, and the temperature was raised to 50°C and kept warm for 30 minutes to prepare the soap solution. Stirring was stopped and set aside.

[0100] S3. 7.4 parts of potassium persulfate and 21.5 parts of soft water were added to the initiator preparation tank and stirred until dissolved, the vacuum was turned on and sucked into the initiator addition tank for use;

[0101] S4. Using the liquid level difference, 71.8 parts of soft water were added to the reactor, the reactor vacuum was turned on, the prepared soap solution, 2.8 parts of tert-dodecyl mercaptan, 11.6 parts of acrylonitrile were pumped into the reactor, replaced with nitrogen twice, and the vacuum was continued to 0.06 MPa. 48.0 parts of butadiene and 9.3 parts of hydroxyethyl methacrylate were injected into the reactor;

[0102] S5. When the reactor steam temperature rises to 40°C, the initiator in the initiator feeding tank is added, and when the temperature rises, the jacket is kept at a constant temperature with ice water;

[0103] S6. Control the temperature until the reaction is completed when the conversion rate is greater than 98%;

[0104] S7. The reaction latex obtained was pressed into a degassing vessel with steam, the degassing vessel was opened, stirred and evacuated through the condenser, 2.9 parts of sodium thiamin, 2.1 parts of an aqueous antioxidant were drawn into the degassing vessel together, the evacuation was continued, and the temperature was raised to 70 ° C with steam, maintaining the temperature and tumbling state, controlling the negative pressure to 0.06MPa~0.08MPa;

[0105] After S8.60min, close the steam and vacuum valves, cool to below 50℃ and discharge the material into the blending kettle;

[0106] S9. Open the blending kettle and stir, slowly add liquid caustic soda to adjust the pH to 8.5 over 30 minutes, and continue stirring for 30 minutes;

[0107] S10. Filter the mixture through a 200-mesh filter through a vibrating screen into a turnover tank and press it into a finished product tank to obtain carboxylated styrene-butadiene latex. The products obtained in Examples 1-5 above were tested for surface strength, viscosity, chemical stability, anti-foaming properties, smoothness, and gloss. All testing methods were in accordance with national standards. The specific results are as follows:

[0108] Table 1 Test results

[0109]

[0110] As can be seen from the test results described in Table 1, Example 2 increases the proportion of acrylonitrile on the basis of Example 1, and the improvement range of surface strength, smoothness and printing gloss is relatively large, and viscosity has also decreased a lot. It can be seen that acrylonitrile can effectively improve the surface strength, bonding strength, smoothness and glossiness of coated paper. Example 3 increases the proportion of functional monomer on the basis of Example 2, and the test values of chemical stability and anti-foaming property are reduced more. It can be seen that functional monomer can effectively improve the chemical stability and anti-foaming property of carboxyl styrene butadiene latex. Example 4 increases the proportion of soft water on the basis of Example 3, and various properties are improved a lot. It can be seen that the addition amount of soft water is large and can improve the reaction conversion rate, while preventing the occurrence of esterification reaction. Example 5 changes the step on the basis of Example 4, and changes all to adding all at the same time by adding raw materials in sequence, and various properties all decline thereupon. It can be seen that adding raw materials in sequence can make mixing more uniform and reaction more complete. Therefore, the carboxyl styrene butadiene latex obtained by the present invention has excellent performance and can give paper excellent performance.

[0111] The foregoing examples are merely illustrative and serve to illustrate some of the features of the method of the present invention. The appended claims are intended to claim the widest possible scope that can be envisioned, and the embodiments presented herein are merely illustrative of selected implementations according to a combination of all possible embodiments. Therefore, it is the applicant's intention that the appended claims are not limited by the selection of examples illustrating the features of the present invention. Some numerical ranges used in the claims also include subranges therein, and variations in these ranges should also be interpreted as being covered by the appended claims where possible.

Claims

1. A process for producing carboxylated styrene-butadiene latex, characterized in that: The following steps are involved: S1. Use a pump to pump acrylonitrile into an acrylonitrile metering tank for use, and pump butadiene into a butadiene metering tank for use; S2. Use the liquid level difference to put soft water into the soap kettle, start stirring, and while stirring, sequentially add the emulsifier, chelating agent, mixing monomer, and sodium bicarbonate into the soap kettle. Heat to 50 ° C and keep warm for 30 minutes to make a soap solution. Stop stirring and set aside. S3. Add the initiator and soft water to the initiator preparation tank and stir until dissolved. Open the vacuum and suck it into the initiator addition tank for use. S4. Soft water was added to the reactor using the liquid level difference, the reactor vacuum was turned on, the soap solution, mercaptan, and acrylonitrile were pumped into the reactor, replaced with nitrogen twice, and the vacuum was continued to 0.06MPa, butadiene and functional monomers were injected into the reactor; S5. When the reactor steam temperature rises to 40°C, inject the initiator in the initiator feeding tank, and when the temperature rises, pass ice water through the jacket to maintain a constant temperature; S6. Control the temperature until the reaction is completed when the conversion rate is greater than 98%; S7. The reaction latex obtained was pressed into a degassing vessel with steam, the degassing vessel was opened, stirred and evacuated through the condenser, sodium thiamethoxam, an aqueous antioxidant was sequentially drawn into the degassing vessel, vacuumed, and the temperature was raised to 70 ° C with steam, maintaining the temperature and tumbling state, controlling the negative pressure of 0.06MPa ~ 0.08MPa; After S8.60min, close the steam and vacuum valves, cool to below 50℃ and discharge the material into the blending kettle; S9. Open the blending kettle and stir, slowly add liquid caustic soda to adjust the pH to 8.5 over 30 minutes, and continue stirring for 30 minutes; S10. Filter through a vibrating screen with a 200-mesh filter into a turnover tank and press into the finished product tank to obtain carboxylated styrene-butadiene latex; All raw materials are calculated by weight: 159.1 ~ 185.4 parts of soft water Acrylonitrile 11.6 to 12.3 parts Butadiene 45.0 ~ 52.6 parts Emulsifier 14.2 ~ 17.3 parts Chelating agent 0.2 ~ 0.5 parts Mixed monomer 56.1 ~ 61.4 parts 3.0 to 5.0 parts sodium bicarbonate Initiator 6.4 ~ 8.7 parts 2.2 to 4.8 parts of mercaptan Functional monomer 9.3 ~ 9.8 parts 2.4 to 3.6 parts of sodium thiamethoxam 1.5 to 2.8 parts of water-based antioxidant; The mixed monomers are 87.3% to 88.5% styrene and 11.5% to 12.7% methacrylic acid in percentage by mass; The functional monomer is one or more of hydroxyethyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl acrylate.

2. A process for producing carboxylated styrene-butadiene latex according to claim 1, characterized in that: The emulsifier is composed of an anionic emulsifier and a nonionic emulsifier in a mass ratio of 3:

1. The anionic emulsifier is one or more of C8-C18 alkylbenzene sulfonate sodium, C8-C18 alkyl sulfate sodium, and C8-C18 alkyldiphenol ether disulfonate sodium. The nonionic emulsifier is one or more of C8-C12 alkylphenol polyoxyethylene ether with an ethylene oxide addition number of 5-20, C8-C12 fatty alcohol polyoxyethylene ether with an ethylene oxide addition number of 5-20, and C4-C8 fatty alcohol polyoxypropylene ether with a propylene oxide addition number of 2-10.

3. A process for producing carboxylated styrene-butadiene latex according to claim 1, characterized in that: The chelating agent is a metal ion chelating agent, including one or more of disodium edetate, tetrasodium edetate and sodium tripolyphosphate.

4. A process for producing carboxylated styrene-butadiene latex according to claim 1, characterized in that: The initiator includes one or more of potassium persulfate, ammonium persulfate, and hydrogen peroxide.

5. A process for producing carboxylated styrene-butadiene latex according to claim 1, characterized in that: The mercaptan is an alkyl mercaptan, including one of ethanedithiol, ethyl mercaptan and tert-dodecyl mercaptan.

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