A low-odor carboxylated styrene-butadiene latex and preparation method thereof

Abstract

The present invention provides a low-odor carboxylated styrene-butadiene latex with complete monomer reaction, high reaction conversion rate and low residual monomer content and a preparation method thereof. The latex comprises 50-60 parts of butadiene, 30-40 parts of styrene, 5-15 parts of acrylic acid, 1-3 parts of emulsifier, 1-3 parts of surfactant, 1-2 parts of initiator, 1-3 parts of alkali agent, 100-150 parts of water and 0.05-0.3 parts of redox agent; the preparation method comprises: adding the emulsifier, surfactant, alkali agent and water into a reaction kettle and dissolving them for 5-10 minutes; heating to 70-80°C, adding one-third of the initiator, and simultaneously dropping butadiene, styrene, acrylic acid and the remaining initiator, stirring continuously for 150-180 minutes, and keeping warm for 2-3 hours; adding the redox agent, and keeping warm for 1 hour; transferring to a degassing reaction kettle, introducing water vapor and nitrogen, degassing for 4-8 hours, and discharging after cooling. The present invention is applied to the field of chemical technology.

Description

Technical Field

[0001] The invention relates to the technical field of chemical industry, and in particular to a low-odor carboxyl styrene-butadiene latex and a preparation method thereof. Background Art

[0002] Carboxylated styrene butadiene latex is a high molecular polymer made by emulsion polymerization of butadiene, styrene, a small amount of carboxylic acid and other additives. It is a milky white liquid with blue light. It is mainly used in papermaking, carpet, textile, construction and other industries. The application of carboxylated styrene butadiene latex in papermaking is very mature. With the development of the papermaking industry, the requirements for the smell of paper are getting higher and higher. Carboxylated styrene butadiene latex for paper coating is an important adhesive in the production process of coated paper in the papermaking industry. The smell of styrene butadiene latex also has a significant impact on the smell of the whole paper.

[0003] Since carboxylated styrene butadiene latex is a high molecular weight organic polymer, there are many unreacted monomers and organic volatile substances in the latex, which cause serious odor problems to carboxylated styrene butadiene latex. The low-odor carboxylated styrene butadiene latex currently on the market cannot meet the low-odor requirements of paper. Summary of the invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art and provide a low-odor carboxylated styrene-butadiene latex with complete monomer reaction, high reaction conversion rate and low residual monomer content.

[0005] The present invention also provides a method for preparing the low-odor carboxylated styrene butadiene latex. The method has simple process and low cost and can obtain carboxylated styrene butadiene latex with lower odor.

[0006] The technical solution adopted by the low-odor carboxylated styrene-butadiene latex of the present invention is, by weight, comprising:

[0007]

[0008] Furthermore, the emulsifier is selected from one or more of alkyl sulfates, alkylbenzene sulfonates, phosphates, fatty acid soaps, polyvinyl alcohol, fatty alcohol polyoxyethylene ethers, and acrylates.

[0009] More specifically, the surfactant is selected from sodium dodecyl sulfate. The initiator is selected from ammonium persulfate. The alkali agent is selected from sodium hydroxide. The redox agent is selected from one or more of tert-butyl hydroperoxide, cumene hydroperoxide, p-isopropyl cumene hydroperoxide, sodium bisulfite, persulfate, and L-ascorbic acid.

[0010] The preparation method of the above-mentioned low-odor carboxyl styrene-butadiene latex comprises the following steps:

[0011] (1) adding an emulsifier, a surfactant, an alkali agent and water into a reaction kettle according to weight proportions and dissolving them for 5 to 10 minutes;

[0012] (2) heating to 70-80° C., adding one third of the initiator by weight, and simultaneously adding butadiene, styrene, acrylic acid and the remaining initiator to the reactor by weight through a raw material pump, stirring and reacting for 150-180 min, controlling the simultaneous addition of butadiene, styrene, acrylic acid and the remaining initiator, and continuing the heat-keeping reaction for 2-3 h after all the raw materials have been added;

[0013] (3) adding a redox reagent in proportion by weight and keeping warm for 1 hour;

[0014] (4) After the reaction is completed, stop heating the reactor, transfer all products to a degassing reactor, introduce water vapor and nitrogen, degas for 4 to 8 hours, discharge the material after natural cooling, and filter with a vibrating screen to obtain the final low-odor carboxylated styrene butadiene latex product.

[0015] The invention has the following beneficial effects: in the invention, the low-odor carboxylated styrene butadiene latex comprises butadiene, styrene, acrylic acid, an emulsifier, a surfactant, an initiator, an alkali agent, water, and a redox reaction agent by weight; the process formula of the invention has a reasonable ratio, can fully and effectively react the added monomers completely, has a high reaction conversion rate, and has a low residual monomer content; by adding the redox reaction agent, the remaining residual monomers are reacted completely, and the residual monomers in the carboxylated styrene butadiene latex are further reduced; in addition, in the preparation process of the invention, a steam+nitrogen combination method is used in a degassing kettle for degassing, the degassing process is simple, and the residual monomers and volatile organic compounds (VOCs) in the carboxylated styrene butadiene latex can be effectively removed; because nitrogen is used to replace steam, the cost is lower than that of conventional steam degassing; in addition, the invention adopts a combination of a chemical method (redox reaction) and a physical method (degassing of a degassing kettle steam and nitrogen combination) to obtain a carboxylated styrene butadiene latex with a lower odor. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0017] By weight, the low-odor carboxylated styrene-butadiene latex of the present invention comprises 50-60 parts of butadiene, 30-40 parts of styrene, 5-15 parts of acrylic acid, 1-3 parts of emulsifier, 1-3 parts of surfactant, 1-2 parts of initiator, 1-3 parts of alkali agent, 100-150 parts of water and 0.05-0.3 parts of redox reaction agent.

[0018] Specifically, the emulsifier is selected from one or more of alkyl sulfate, alkylbenzene sulfonate, phosphate, fatty acid soap, polyvinyl alcohol, fatty alcohol polyoxyethylene ether, and acrylate. The surfactant is selected from sodium dodecyl sulfate. The initiator is selected from ammonium persulfate. The alkali agent is selected from sodium hydroxide. The redox reaction agent is selected from one or more of tert-butyl hydroperoxide, cumene hydroperoxide, p-isopropyl cumene hydroperoxide, sodium bisulfite, persulfate, and L-ascorbic acid.

[0019] like Figure 1 As shown, the preparation method of the above-mentioned low-odor carboxyl styrene butadiene latex comprises the following steps:

[0020] (1) adding an emulsifier, a surfactant, an alkali agent and water into a reaction kettle according to weight proportions and dissolving them for 5 to 10 minutes;

[0021] (2) heating to 70-80° C., adding one third of the initiator by weight, and simultaneously adding butadiene, styrene, acrylic acid and the remaining initiator to the reactor by weight through a raw material pump, stirring and reacting for 150-180 min, controlling the simultaneous addition of butadiene, styrene, acrylic acid and the remaining initiator, and continuing the heat-keeping reaction for 2-3 h after all the raw materials have been added;

[0022] (3) adding a redox reagent in proportion by weight and keeping warm for 1 hour;

[0023] (4) After the reaction is completed, stop heating the reactor, transfer all products to a degassing reactor, introduce water vapor and nitrogen, degas for 4 to 8 hours, discharge the material after natural cooling, and filter with a vibrating screen to obtain the final low-odor carboxylated styrene butadiene latex product.

[0024] The present invention solves the odor problem of carboxylated styrene butadiene latex by means of a chemical method (oxidation-reduction reaction) and a physical method (vacuum degassing), so that the carboxylated styrene butadiene latex has very low odor and VOCs (volatile organic compounds), meeting the requirements of high-end products such as food packaging paper, etc. The present invention is described in detail with specific test examples.

[0025] Test 1:

[0026] This test provides a low-odor carboxylated styrene-butadiene latex, which comprises the following parts by weight: 60 parts of butadiene, 30 parts of styrene, 10 parts of acrylic acid, 2 parts of emulsifier 2A1 (emulsifier: sodium dodecyl diphenyl ether disulfonate), 2 parts of sodium dodecyl sulfate (anionic surfactant), 1.5 parts of ammonium persulfate (initiator), 2 parts of sodium hydroxide (alkali agent), 120 parts of water, 0.1 parts of tert-butyl hydroperoxide, and 0.05 parts of L-ascorbic acid.

[0027] The preparation method for this test is as follows:

[0028] (1) Add emulsifier 2A1, sodium lauryl sulfate, sodium hydroxide and water into a reaction kettle and dissolve for 5 to 10 minutes;

[0029] (2) heating to 70-80°C, adding one-third of ammonium persulfate, and simultaneously adding butadiene, styrene, acrylic acid, and the remaining ammonium persulfate into the reactor through a raw material pump, stirring and reacting for 150-180 minutes, controlling the simultaneous addition of the above four raw materials, and after all the raw materials have been added, continuing the heat preservation reaction for 2-3 hours;

[0030] (3) Maintaining the temperature at 75°C, add tert-butyl hydroperoxide and sodium bisulfite and continue to keep warm for 1 hour;

[0031] (4) After the reaction is completed, the heating of the reactor is stopped, all the products are transferred to the reactor, 100% 2MPa steam is introduced, degassing for 2h, and the material is discharged after natural cooling and filtered with a vibrating screen to obtain the final low-odor carboxylated styrene butadiene latex product.

[0032] The low-odor carboxylated styrene-butadiene latex prepared in this experiment is denoted as A1.

[0033] Test 2:

[0034] The specific implementation of this experiment is the same as that of Experiment 1, except that the amount of the redox agent, L-ascorbic acid, is 0.1 part. The low-odor carboxylated styrene-butadiene latex prepared in this experiment is denoted as A2.

[0035] Test 3:

[0036] The specific implementation method of this experiment is the same as that of Experiment 2, except that: in step (3) of the preparation method, the insulation temperature is 60°C; the low-odor carboxylated styrene-butadiene latex prepared in this experiment is denoted as A3.

[0037] Test 4:

[0038] The specific implementation method of this experiment is the same as that of Experiment 3, except that: in step (4) of the preparation method, the steam degassing time is 6 hours; the low-odor carboxylated styrene-butadiene latex prepared in this experiment is recorded as A4.

[0039] Test 5:

[0040] The specific implementation method of this experiment is the same as that of Experiment 4, except that: in step (4) of the preparation method, the 100% 2MPa steam introduced is replaced with 80% 2MPa steam + 20% nitrogen; the low-odor carboxylated styrene butadiene latex prepared in this experiment is recorded as A5.

[0041] The following is a comparative test example.

[0042] Comparative test 1:

[0043] The specific implementation method of this experiment is the same as that of Experiment 5, except that: the redox reaction agent - 0.1 part of L-ascorbic acid is replaced by 0.1 part of sodium bisulfite; the carboxylated styrene butadiene latex prepared in this experiment is recorded as B1.

[0044] Comparative test 2:

[0045] The specific implementation method of this experiment is the same as that of Experiment 5, except that: in step (4) of the preparation method, the steam degassing time is 4 hours; the carboxylated styrene butadiene latex prepared in this experiment is recorded as B2.

[0046] Comparative test 3:

[0047] The specific implementation method of this experiment is the same as that of Experiment 5, except that: in step (4) of the preparation method, the 80% 2MPa steam + 20% nitrogen introduced is replaced with 50% 2MPa steam + 50% nitrogen; the carboxylated styrene butadiene latex prepared in this experiment is recorded as B3.

[0048] Comparative test 4:

[0049] The specific implementation method of this experiment is the same as that of Experiment 5, except that: in the preparation method, step (3) is not performed and step (4) is directly performed; the carboxylated styrene butadiene latex prepared in this experiment is recorded as B4.

[0050] Comparative test 5:

[0051] The specific implementation method of this experiment is the same as that of Experiment 5, except that: in the preparation method, step (4) is not performed; the carboxylated styrene butadiene latex prepared in this experiment is recorded as B5.

[0052] Comparative test 6:

[0053] The specific implementation method of this experiment is the same as that of Experiment 5, except that: in the preparation method, steps (3) and (4) are not performed; the low-odor carboxylated styrene-butadiene latex prepared in this experiment is denoted as B6.

[0054] Performance evaluation:

[0055] 1. Odor evaluation: sensory evaluation method was used; latex odor evaluation referred to HG / T4065-2008 "Adhesive Odor Evaluation Method" and SN / T 3179-2012 "Food Contact Materials Test Method Paper and Paperboard Sensory Analysis Odor". Six odor evaluators conducted rating tests on the odor of food packaging paper, and the latex odor evaluation level was graded from 1 to 5.

[0056] 2. VOCs (volatile organic compounds) evaluation: The VOCs detection method adopted in the present invention refers to "GB / T 25260.1-2022 Synthetic latex Part 1: Carboxylated styrene butadiene latex (XSBRL) 56C, 55B".

[0057]

[0058]

[0059] Through experiments 1 to 5 and comparative experiments 1 to 6, it can be seen that the low-odor carboxylated styrene butadiene latex and the preparation method thereof provided by the present invention have low odor and low VOCs content, and are suitable for promotion in the field of low-odor papermaking, especially in the field of food packaging, and have broad development prospects. Among them, experiment 5 has the best odor and VOCs content.

[0060] Finally, it should be emphasized that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various changes and modifications. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a low-odor carboxylated styrene-butadiene latex, characterized in that: The low odor carboxylated styrene-butadiene latex comprises, by weight: Butadiene 60 parts, styrene 30 parts, acrylic acid 10 parts, emulsifier 2A1 2 parts, sodium lauryl sulfate 2 parts, ammonium persulfate 1.5 parts, sodium hydroxide 2 parts, water 120 parts, tert-butyl hydroperoxide 0.1 parts, L-ascorbic acid 0.1 parts; The preparation method of the above-mentioned low-odor carboxyl styrene-butadiene latex comprises the following steps: (1) Add emulsifier 2A1, sodium dodecyl sulfate, sodium hydroxide and water into the reactor and dissolve for 5 to 10 minutes; (2) Heat to 70-80°C, add one-third of ammonium persulfate, and simultaneously add butadiene, styrene, acrylic acid, and the remaining ammonium persulfate into the reactor through a raw material pump, continue stirring and reacting for 150-180 minutes, control the simultaneous addition of the above four raw materials, and after all the raw materials have been added, continue to keep the temperature for 2-3 hours; (3) Maintain the temperature at 60°C, add tert-butyl hydroperoxide and L-ascorbic acid, and continue to keep warm for 1 hour; (4) After the reaction is completed, stop heating the reactor, transfer all the products to the reactor, introduce 100% 2MPa steam, degas for 6 hours, discharge the product after natural cooling, and filter it with a vibrating screen to obtain the final low-odor carboxylated styrene butadiene latex product.

2. A method for preparing a low-odor carboxylated styrene-butadiene latex, characterized in that: The low odor carboxylated styrene-butadiene latex comprises, by weight: Butadiene 60 parts, styrene 30 parts, acrylic acid 10 parts, emulsifier 2A1 2 parts, sodium lauryl sulfate 2 parts, ammonium persulfate 1.5 parts, sodium hydroxide 2 parts, water 120 parts, tert-butyl hydroperoxide 0.1 parts, L-ascorbic acid 0.1 parts; The preparation method of the above-mentioned low-odor carboxyl styrene-butadiene latex comprises the following steps: (1) Add emulsifier 2A1, sodium dodecyl sulfate, sodium hydroxide and water into the reactor and dissolve for 5 to 10 minutes; (2) Heat to 70-80°C, add one-third of ammonium persulfate, and simultaneously add butadiene, styrene, acrylic acid, and the remaining ammonium persulfate into the reactor through a raw material pump, continue stirring and reacting for 150-180 minutes, control the simultaneous addition of the above four raw materials, and after all the raw materials have been added, continue to keep the temperature for 2-3 hours; (3) Maintain the temperature at 60°C, add tert-butyl hydroperoxide and L-ascorbic acid, and continue to keep warm for 1 hour; (4) After the reaction is completed, stop heating the reactor, transfer all the products to the reactor, introduce 80% 2MPa steam + 20% nitrogen, degas for 6 hours, discharge the product after natural cooling, and filter it with a vibrating screen to obtain the final low-odor carboxylated styrene butadiene latex product.

Images