Styrene-butadiene latex for carpet and preparation method thereof

Abstract

The invention belongs to the technical field of latex materials, and relates to a styrene-butadiene latex for carpets and a preparation method thereof, through molecular structure modification, monomer optimization combination, crosslinking system design and other technical means, specific functional groups are introduced into a latex molecular chain, and functional monomers, a crosslinking agent, nanoparticles and the like are added. Compared with traditional latex, the prepared styrene-butadiene latex has the advantages that the bonding strength is improved by 40-60%, the water resistance, the stain resistance and the aging resistance are obviously improved, the odor is obviously reduced, the quality of a carpet can be effectively improved, and the service life of the carpet can be effectively prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of latex materials, and particularly to a styrene-butadiene latex for carpets and a preparation method thereof. Background Art

[0002] As a common floor decoration material, carpets are widely used in homes, commercial places, etc. Styrene-butadiene latex, as an important binder in carpet production, has a crucial impact on the performance of carpets. However, there are many problems with the styrene-butadiene latex for carpets currently on the market, which restricts the improvement of carpet product quality. The bonding force between traditional styrene-butadiene latex for carpets and carpet fibers is limited, resulting in phenomena such as fiber shedding and fuzzing during carpet use, seriously affecting the beauty and service life of carpets.

[0003] In a humid environment, the existing styrene-butadiene latex is prone to hydrolysis and other reactions, resulting in a decrease in bonding performance, and problems such as delamination and deformation of carpets are likely to occur. The surface of carpets made of ordinary styrene-butadiene latex is prone to adsorbing dust, stains, etc., and is difficult to clean, making it difficult to meet the requirements of modern consumers for the convenience of carpet cleaning and maintenance. When exposed to environmental factors such as light and temperature changes for a long time, the styrene-butadiene latex will age, leading to the deterioration of the physical properties of carpets, such as a decrease in elasticity and hardening. Some styrene-butadiene latexes will release unpleasant odors during use, affecting indoor air quality and potentially harming human health. Summary of the Invention

[0004] The present invention provides a styrene-butadiene latex for carpets. The molecular structure of the styrene-butadiene latex contains functional groups such as epoxy groups and hydroxyl groups, and the content of these functional groups accounts for 0.8%-4% of the total molecular mass; the latex particle size is distributed between 100-150 nm, and the particle size distribution index (PDI) is less than 0.18; the solid content is 45%-55%, and the viscosity is 80-200 mPa·s (25°C); it has a moderate cross-linked structure, and the cross-linking degree is 12%-35%; the latex contains nanoparticles with a mass fraction of 0.5%-2%.

[0005] Further, the nanoparticles are one or more of nano-titanium dioxide and nano-zinc oxide.

[0006] Further, the styrene-butadiene latex is prepared by a seed emulsion polymerization method, and a composite emulsifier system is used during the polymerization process.

[0007] Furthermore, a preparation method of styrene-butadiene latex for carpets comprises the following steps: preparing raw materials such as butadiene, styrene, methyl acrylate, functional monomers containing epoxy groups or hydroxyl groups, crosslinking agents, composite emulsifiers, initiators, and nanoparticles; adding deionized water, a part of the composite emulsifier, and a part of the initiator into a reaction kettle, stirring evenly and heating to 60-70°C, slowly dropping a small amount of a mixed monomer solution of butadiene, styrene, and functional monomers, and reacting for a period of time to obtain a seed emulsion; continuously dropping the remaining mixed monomer solution of butadiene, styrene, methyl acrylate, and functional monomers into the seed emulsion, and simultaneously dropping the remaining initiator solution, controlling the dropping rate, and maintaining the reaction temperature at 70-80°C; when the polymerization reaction is nearly completed, cooling to 60-70°C, adding an appropriate amount of crosslinking agent, and stirring and reacting for 40-70 minutes to form a crosslinked structure; pretreating the nanoparticles, and slowly adding them into the latex under stirring, and continuing to stir for 30-60 minutes to make them evenly dispersed; subjecting the reacted latex to vacuum distillation to remove unreacted monomers and low-boiling substances, then filtering through a precision filtering device to remove impurities, and finally adjusting the solid content of the latex to 45%-55%.

[0008] Furthermore, the composite emulsifier system is composed of an anionic emulsifier and a nonionic emulsifier mixed in a ratio of 1-2:1.

[0009] Furthermore, the initiator is azobisisobutyronitrile (AIBN), and its dosage and addition timing are precisely controlled.

[0010] Furthermore, the crosslinking agent is a polyfunctional isocyanate crosslinking agent.

[0011] Furthermore, in the process of preparing the raw materials, the method for pretreating the nanoparticles is as follows: First, disperse the nanoparticles in ethanol to form a nanoparticle dispersion; the concentration of the nanoparticles in the dispersion is controlled at a mass fraction of 5%-10%; then, add a coupling agent to the dispersion, and the addition amount of the coupling agent is 2%-5% of the mass of the nanoparticles; stir and react for 30-60 minutes under ultrasonic assistance to make the coupling agent fully react with the active groups such as hydroxyl groups on the surface of the nanoparticles; finally, dry the nanoparticle dispersion treated with the coupling agent in a vacuum drying oven at 60-80°C for 2-4 hours to remove the organic solvent, and obtain the pretreated nanoparticle powder for standby.

[0012] Furthermore, in the process of preparing the seed emulsion, the ratio of butadiene, styrene, and functional monomers in the dropped mixed monomer solution is 3-5:2-3:1 to control the performance of the seed emulsion.

[0013] Furthermore, using the above-mentioned styrene-butadiene latex for carpets as a binder, the carpet has good bonding performance, water resistance, stain resistance, aging resistance, and the odor meets the indoor air quality standard.

[0014] Beneficial technical effects:

[0015] Significant improvement in bonding strength: Through molecular structure modification and crosslinking system design, a stronger bonding force is formed between styrene-butadiene latex and carpet fibers. The bonding strength is increased by 40%-60% compared with traditional latex, effectively reducing the shedding and fuzzing of carpet fibers.

[0016] Remarkable enhancement in water resistance: The optimized monomer combination, crosslinking structure, and the composite effect of nanoparticles improve the hydrolysis stability of the latex in a humid environment, and the water resistance is increased by 50%-70%. The carpet is not easily delaminated and deformed in a humid environment.

[0017] Excellent stain resistance and antibacterial properties: The photocatalytic and antibacterial properties of nanoparticles make the stains on the carpet surface easier to decompose and remove. The stain resistance is increased by 60%-80%, and at the same time, it has good antibacterial properties, with an inhibition rate of more than 90% against common bacteria.

[0018] Good aging resistance: The synergistic effect of additives and the protection of the crosslinking structure slow down the aging rate of the latex under environmental factors such as light and temperature changes. After 500 hours of artificial accelerated aging test, the physical property retention rate is above 85%.

[0019] Significantly reduced odor: Through the post-treatment process, unreacted monomers and low-boiling substances are removed, and the odor of the latex is significantly reduced, meeting the indoor air quality standard and being harmless to human health. Specific implementation manners

[0020] Example 1

[0021] Raw material preparation:

[0022] Butadiene: 110 g

[0023] Styrene: 45 g

[0024] Methyl acrylate: 15 g

[0025] Glycidyl acrylate (functional monomer): 3 g

[0026] Toluene diisocyanate (crosslinking agent): 4 g

[0027] Sodium dodecylbenzenesulfonate (anionic emulsifier): 2.5 g

[0028] Polyoxyethylene fatty alcohol ether (non-ionic emulsifier): 1.5 g

[0029] 2,2'-Azobis(2-methylpropionitrile) (AIBN): 0.6 g

[0030] Nano-titanium dioxide: 1 g

[0031] Deionized water: 230 g

[0032] Seed emulsion preparation: In a reaction kettle equipped with a stirrer, thermometer, dropping funnel, and reflux condenser, add deionized water, 2.5 g of sodium dodecylbenzenesulfonate, 1.5 g of polyoxyethylene fatty alcohol ether, and 0.2 g of AIBN. Stir evenly and heat up to 65°C. Slowly dropwise add a mixed monomer solution of 5 g of butadiene, 3 g of styrene, and 1 g of glycidyl acrylate, and react for 1 hour to obtain a seed emulsion.

[0033] Emulsion polymerization: Continuously dropwise add the remaining mixed monomer solution of butadiene, styrene, methyl acrylate, and glycidyl acrylate to the seed emulsion, and at the same time dropwise add a solution of 0.4 g of AIBN dissolved in an appropriate amount of deionized water. The dropping rate is controlled at 13% of the total monomer amount per hour, and the reaction temperature is maintained at 75°C.

[0034] Crosslinking reaction: When the polymerization reaction is approaching the end, cool down to 65°C, add 4 g of toluene diisocyanate, and stir and react for 60 minutes.

[0035] Nanoparticle addition: After surface modification pretreatment of nano-titanium dioxide, slowly add it to the latex under stirring conditions, and continue stirring for 45 minutes.

[0036] For the surface modification pretreatment of nano-titanium dioxide: First, disperse nano-titanium dioxide in an appropriate amount of organic solvent, such as ethanol or acetone, to form a nano-titanium dioxide dispersion. The concentration of nano-titanium dioxide in the dispersion can be controlled at 5%-10% (mass fraction). Then, add an appropriate amount of coupling agent, such as silane coupling agent KH-550 or titanate coupling agent NDZ-101, to the dispersion. The addition amount of the coupling agent is 2%-5% of the mass of nano-titanium dioxide. Stir and react for 30-60 minutes under ultrasonic assistance to enable the coupling agent to fully react with the active groups such as hydroxyl groups on the surface of nano-titanium dioxide, improving the compatibility and dispersibility of nano-titanium dioxide with the polymer matrix. Finally, dry the nano-titanium dioxide dispersion treated with the coupling agent in a vacuum drying oven at 60-80°C for 2-4 hours to remove the organic solvent, obtaining the pretreated nano-titanium dioxide powder for standby.

[0037] Post-treatment:

[0038] Perform vacuum distillation on the reacted latex to remove unreacted monomers and low-boiling substances.

[0039] Then filter through a 0.2 μm precision filter to remove impurities.

[0040] Finally, adjust the solid content of the latex to 50%.

[0041] Example 2

[0042] Raw material preparation:

[0043] Butadiene: 105 g

[0044] Styrene: 48 g

[0045] Methyl acrylate: 12 g

[0046] 2-Hydroxyethyl acrylate (functional monomer): 4 g

[0047] Hexamethylene diisocyanate (crosslinking agent): 5 g

[0048] Sodium dodecyl sulfate (anionic emulsifier): 2 g

[0049] Nonylphenol polyoxyethylene ether (nonionic emulsifier): 1 g

[0050] Azobisisobutyronitrile (AIBN): 0.7 g

[0051] Nano zinc oxide: 1.5 g

[0052] Deionized water: 220 g

[0053] Seed emulsion preparation: Add deionized water, 2 g of sodium dodecyl sulfate, 1 g of nonylphenol polyoxyethylene ether and 0.25 g of AIBN into the reaction kettle, stir evenly and heat up to 60 °C. Slowly dropwise add the mixed monomer solution of 6 g of butadiene, 4 g of styrene and 1 g of 2-hydroxyethyl acrylate, and react for 1.2 hours to obtain the seed emulsion.

[0054] Emulsion polymerization: Continuously dropwise add the remaining mixed monomer solution and initiator solution into the seed emulsion, and the dropping rate is 10% of the total monomer amount per hour, and keep the reaction temperature at 70 °C.

[0055] Crosslinking reaction: When the polymerization reaction is nearly completed, cool down to 60 °C, add 5 g of hexamethylene diisocyanate, and stir and react for 70 minutes.

[0056] Nano particle addition: After the nano zinc oxide is pretreated, add it to the latex and stir for 50 minutes.

[0057] The pretreatment of nano particles is as follows: Place the nano zinc oxide in a ball mill, add an appropriate amount of dispersant, such as polyvinylpyrrolidone (PVP), and the mass ratio of the dispersant to the nano zinc oxide is 1:10 - 1:5. The ball milling time is 2 - 4 hours, and the ball milling speed is controlled at 300 - 500 revolutions per minute to further refine and uniformly disperse the nano zinc oxide particles.

[0058] Next, the ball-milled nano-zinc oxide is dispersed in deionized water to form a nano-zinc oxide suspension with a concentration of about 8%-12% (mass fraction). An appropriate amount of surfactant, such as sodium dodecylbenzenesulfonate, is added dropwise to the suspension, and the addition amount of the surfactant is 1%-3% of the mass of nano-zinc oxide. Stir and react for 40-70 minutes to adsorb a layer of surfactant molecules on the surface of nano-zinc oxide, enhancing its dispersion stability in the latex. Finally, the pretreated nano-zinc oxide is collected by centrifugal separation, washed 2-3 times with deionized water to remove the excess surfactant and impurities, and dried to constant weight at 50-70 °C to obtain nano-zinc oxide that can be added to the latex.

[0059] Post-treatment:

[0060] The reacted latex is subjected to vacuum distillation to remove unreacted monomers and low-boiling substances.

[0061] Then it is filtered through a 0.2 μm precision filter to remove impurities.

[0062] Finally, the solid content is adjusted to 48%.

[0063] Comparative Example 1

[0064] The traditional preparation method of styrene-butadiene latex for carpets is adopted, without adding functional monomers, crosslinking agents and nanoparticles, and other conditions are the same as those in Example 1.

[0065] Performance testing

[0066] Bond strength test: According to relevant standards, the prepared styrene-butadiene latex is used for bonding carpet fibers, and its bond strength is tested.

[0067] Water resistance test: The carpet sample coated with latex is immersed in water for a certain time, and its delamination and deformation are observed, and the change of bonding performance is tested.

[0068] Stain resistance test: Simulate daily stain pollution of the carpet, and test the cleanliness of the carpet surface after cleaning.

[0069] Aging resistance test: Through artificial accelerated aging test, test the change of physical properties of the latex under conditions such as light and temperature change.

[0070] Odor test: Through professional odor detection equipment and methods, evaluate the odor intensity and composition of the latex.

[0071] Test results

[0072]

[0073]

[0074] As can be seen from the test results, the styrene-butadiene latex for carpets prepared by the present invention is significantly superior to the traditional styrene-butadiene latex in terms of bonding strength, water resistance, stain resistance, aging resistance and odor.

[0075] Precautions

[0076] In the raw material preparation stage, the purity and quality of the raw materials should be strictly controlled to ensure that the raw materials meet the production requirements and avoid affecting the latex performance due to raw material problems.

[0077] During the preparation of the seed emulsion and the emulsion polymerization process, the temperature, dropping rate and initiator dosage should be precisely controlled to ensure the smooth progress of the polymerization reaction and the stability of the product.

[0078] During the crosslinking reaction, according to the properties and dosage of the crosslinking agent, the reaction temperature and time should be reasonably controlled to avoid excessive or insufficient crosslinking, which may affect the latex performance.

[0079] When adding nanoparticles, it is necessary to ensure the uniform dispersion of the nanoparticles, which can be achieved through appropriate pretreatment and stirring methods.

[0080] During the post-treatment process, the conditions of vacuum distillation and filtration should be optimized according to the characteristics of the latex to ensure the effective removal of impurities and unreacted monomers without affecting the latex performance.

[0081] Summary

[0082] Through the innovative improvement of the molecular structure, preparation process, etc. of the styrene-butadiene latex for carpets, the present invention has successfully solved the problems existing in the prior art, such as insufficient bonding strength, poor water resistance, poor stain resistance, weak aging resistance and odor problems. The prepared styrene-butadiene latex has excellent comprehensive performance, can significantly improve the quality and service life of carpets, meet the market demand for high-quality carpets, and has good market application prospects.

Claims

1. A styrene-butadiene latex for carpet, characterized in that: The molecular structure of the styrene-butadiene latex contains epoxy and hydroxyl functional groups, the content of which accounts for 0.8%-4% of the total molecular mass; the latex particle size distribution is between 100-150nm, and the particle size distribution index is less than 0.18; the solid content is 45%-55%, and the viscosity is 80-200mPa·s; it has a cross-linked structure, and the cross-linking degree is 12%-35%; the latex contains 0.5%-2% of nanoparticles by mass.

2. The styrene-butadiene latex for carpet according to claim 1, characterized in that: The nanoparticles are one or more of nano titanium dioxide and nano zinc oxide.

3. The styrene-butadiene latex for carpet according to claim 1, characterized in that: The styrene-butadiene latex is prepared by a seed emulsion polymerization method, and a composite emulsifier system is used in the polymerization process.

4. A method for preparing styrene-butadiene latex for carpet, characterized in that: The following steps are involved: Preparation Butadiene, styrene, methyl acrylate, functional monomers containing epoxy or hydroxyl groups, crosslinking agents, composite emulsifiers, initiators, and nanoparticle raw materials; deionized water, part of the composite emulsifier and part of the initiator are added to a reaction kettle, stirred evenly and heated to 60-70° C., a small amount of a mixed monomer solution of butadiene, styrene and functional monomers is slowly dripped, and a reaction is performed for a period of time to obtain a seed emulsion; the remaining butadiene, styrene, methyl acrylate and the mixed monomer solution of functional monomers are continuously dripped into the seed emulsion, and the remaining The initiator solution is added at a controlled rate to maintain the reaction temperature at 70-80°C; when the polymerization reaction is nearly finished, the temperature is lowered to 60-70°C, an appropriate amount of a crosslinking agent is added, and the reaction is stirred for 40-70 minutes to form a crosslinked structure; after pre-treating the nanoparticles, the nanoparticles are slowly added to the latex under stirring, and the stirring is continued for 30-60 minutes to make them uniformly dispersed; the latex after the reaction is subjected to reduced pressure distillation to remove unreacted monomers and low-boiling substances, and then filtered to remove impurities, and finally the solid content of the latex is adjusted to 45%-55%.

5. The preparation method according to claim 4, characterized in that: The composite emulsifier system is composed of an anionic emulsifier and a nonionic emulsifier mixed in a ratio of 1-2:

1.

6. The preparation method according to claim 4, characterized in that: The initiator is azobisisobutyronitrile, and its dosage and addition timing are precisely controlled.

7. The preparation method according to claim 4, characterized in that: The crosslinking agent is a multifunctional isocyanate crosslinking agent.

8. The preparation method according to claim 4, characterized in that: During the raw material preparation process, the method for pretreating the nanoparticles is as follows: first, the nanoparticles are dispersed in ethanol to form a nanoparticle dispersion; the concentration of the nanoparticles in the dispersion is controlled at a mass fraction of 5%-10%; then, a coupling agent is added to the dispersion, and the amount of the coupling agent added is 2%-5% of the mass of the nanoparticles; the reaction is stirred for 30-60 minutes under the assistance of ultrasound to allow the coupling agent to fully react with active groups such as hydroxyl groups on the surface of the nanoparticles; finally, the nanoparticle dispersion treated with the coupling agent is dried in a vacuum drying oven at 60-80° C. for 2-4 hours to remove the organic solvent and obtain the pretreated nanoparticle powder for later use.

9. The preparation method according to claim 4, characterized in that: During the preparation of the seed emulsion, the ratio of butadiene, styrene and functional monomer in the mixed monomer solution added dropwise is 3-5:2-3:1 to control the performance of the seed emulsion.

10. A carpet, characterized in that: The styrene-butadiene latex for carpet described in any one of claims 1 to 3 is used as a binder. The carpet has good bonding performance, water resistance, stain resistance, aging resistance, and the odor meets the indoor air quality standard.

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