A kh570 composite polymer modified pvac emulsion and a preparation method thereof
By combining acrylic acid intercalation-modified organobentonite and silane coupling agent KH570, the performance of PVAc emulsion in humid environments was improved, achieving simultaneous enhancement of water resistance, thermal stability and mechanical properties.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHONGJUN MINING (XINJIANG) CO LTD
- Filing Date
- 2026-03-30
- Publication Date
- 2026-05-29
AI Technical Summary
Traditional PVAc emulsions are prone to absorbing water and swelling in humid environments, resulting in decreased strength. They also lack adhesion, heat resistance, and mechanical properties. Existing modification methods are insufficient to simultaneously improve water resistance, thermal stability, and mechanical properties.
Acrylic intercalation-modified organic bentonite was used to expand the interlayer spacing. Combined with silane coupling agent KH570 and PVAc, the PVAc/OMMT/PKH570 composite emulsion was formed through in-situ polymerization intercalation process.
It significantly improves the water resistance, thermal stability and mechanical properties of PVAc emulsion, increases tensile strength, significantly improves both the initial decomposition temperature and the maximum decomposition temperature, and reduces water absorption and water-soluble content.
Smart Images
Figure CN122103478A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of polymer materials technology, specifically to a KH570 composite polymer modified PVAc emulsion and its preparation method. Background Technology
[0002] Polyvinyl acetate (PVAc) emulsion, commonly known as white glue, is an important water-based adhesive widely used in wood processing, construction and decoration, textiles, and papermaking due to its advantages such as being non-toxic, odorless, inexpensive, and easy to use. However, the molecular structure of traditional unmodified PVAc emulsions contains a large number of hydrophilic groups (such as ester groups), resulting in poor water resistance of the cured film. In humid environments, it easily absorbs water, swells, and experiences a decrease in strength. Furthermore, its adhesion, heat resistance, and mechanical properties are also insufficient, limiting its use in high-performance applications.
[0003] To improve the performance of PVAc emulsions, existing technologies typically employ methods such as copolymerization modification, crosslinking modification, or physical blending. However, these methods often suffer from problems such as limited modification effects, uneven filler dispersion, and poor interfacial bonding, making it difficult to simultaneously achieve a comprehensive improvement in water resistance, thermal stability, and mechanical properties.
[0004] Silane coupling agents, due to their unique dual-functional group structure (one end reacting with inorganic substances and the other with organic polymers), are effective modifiers for improving organic-inorganic interface compatibility. Acrylic monomers, under the action of initiators, can be graft copolymerized with vinyl acetate to form a macromolecular network structure, thereby improving the water resistance, thermal stability, and bonding strength of PVAc emulsions.
[0005] Therefore, developing a modification method that can simultaneously improve the water resistance, thermal stability, and mechanical properties of PVAc emulsions, and that is simple to process and easy to industrialize, has significant practical importance and market value. Summary of the Invention
[0006] In view of this, the present invention provides a PVAc emulsion modified with KH570 composite polymer and its preparation method. The present invention uses organic bentonite modified by acrylic acid intercalation to make it have C=C double bonds in the interlayer and realize the interlayer spacing expansion, so that it can participate in the polymerization reaction of vinyl acetate monomer. Through in-situ polymerization intercalation process, vinyl acetate monomer enters the interlayer of OMMT and undergoes polymerization, solving the problem of poor dispersibility of bentonite. PKH570, OMMT and PVAc are compounded and synergistically modified to give full play to the performance advantages of each component and realize the simultaneous improvement of water resistance, thermal stability and mechanical properties of PVAc emulsion.
[0007] The technical solution provided by this invention is as follows: This invention provides a method for preparing a KH570 composite polymer modified PVAc emulsion, comprising the following steps: S1. Preparation of PKH570 polymer KH570, ethanol, deionized water, hydrochloric acid and hydroquinone were added sequentially to the reaction vessel and mixed evenly to obtain a crude product. The crude product was then distilled under reduced pressure to obtain PKH570. S2. Preparation of VAc / OMMT preemulsion PVA and deionized water were added to the reactor and heated and stirred until completely dissolved. The solution was cooled and then acrylic intercalated modified organobentonite, sodium dodecyl sulfate, OP-10 and vinyl acetate were added in sequence. The mixture was stirred evenly to carry out pre-emulsification and obtain VAc / OMMT pre-emulsified solution. S3. Preparation of PVAc / OMMT / PKH570 composite emulsion Add ammonium persulfate solution to the VAc / OMMT pre-emulsion obtained in step S2, heat to 65-75℃, and maintain the temperature for 30-50 minutes. Slowly add a mixture of PKH570 and vinyl acetate through a dropping funnel while simultaneously adding ammonium persulfate solution. After the addition is complete, raise the temperature to 80-90℃ and maintain the temperature for 20-40 minutes. After the reaction is complete, cool to below 50℃, add 4 parts of dibutyl phthalate, stir evenly, and finally cool to room temperature to obtain PVAc / OMMT / PKH570 composite emulsion, which is a PVAc emulsion modified by KH570 composite polymer.
[0008] Preferably, in step S1, the mass ratio of KH570, ethanol, deionized water, hydrochloric acid and hydroquinone is (30-40):(14-16):(3-7):(0.02-0.05):(0.008-0.015), and the concentration of hydrochloric acid is 0.1-1 mol / L.
[0009] Preferably, the reaction temperature in step S1 is 65-75℃ and the reaction time is 8-10h.
[0010] Preferably, in step S2, the mass ratio of PVA, deionized water, acrylic acid-intercalated modified organobentonite, sodium dodecyl sulfate, OP-10 and vinyl acetate is (3-5):(90-120):1.5:0.2:0.5:(10-20).
[0011] Preferably, in step S2, the temperature is heated to 85-95°C, cooled to below 50°C, and the pre-dispersion stirring time is 2-3 hours.
[0012] Preferably, the mass ratio of PKH570 to vinyl acetate in step S3 is (0.4-2.8):(20-30).
[0013] Based on the same inventive concept, the present invention provides a KH570 composite polymer modified PVAc emulsion, which is prepared by the preparation method of the KH570 composite polymer modified PVAc emulsion described in any one of the above claims.
[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention combines the structural characteristics and performance advantages of silane coupling agents and organobentonite to modify PVAc emulsions. It addresses the shortcomings of PVAc in terms of poor water resistance and heat resistance by modifying it. Compared with the modification of a single substance, it has a more significant effect, and the mechanical properties of the latex film can also be significantly improved. This meets the new requirements of the materials industry for PVAc emulsions and expands the application range of PVAc emulsions.
[0015] 2. The present invention successfully prepared a PVAc / OMMT / PKH570 composite emulsion. The test results show that the modified composite emulsion has good water resistance, thermal stability and significantly improved tensile properties. The initial decomposition temperature increased by 17.9℃, the maximum decomposition temperature increased by 15.0℃, the water absorption rate and water-soluble content were significantly reduced, and the tensile strength was increased to 24.5 MPa.
[0016] 3. This performance improvement stems from the synergistic effect of PKH570 and OMMT. While fully leveraging its advantages in water resistance, high and low temperature resistance, weather resistance, and oxidation resistance, the silane coupling agent KH570's unique "molecular bridge" structure effectively improves the dispersibility and interfacial adhesion of bentonite in PVAc emulsions, maximizing the reinforcing effect of bentonite. Its modification effect is significantly better than that of single-component modification. Attached Figure Description
[0017] Figure 1 The infrared spectrum of the PKH570 polymer prepared in an embodiment of the present invention.
[0018] Figure 2 The thermogravimetric curves are shown for the pure PVAc latex membrane prepared in Comparative Example 1, the PVAc / PKH570 latex membrane prepared in Comparative Example 2, and the PVAc / OMMT / PKH570 latex membrane prepared in Example 3.
[0019] Figure 3 This is a comparison chart of the tensile properties of the pure PVAc latex film prepared in Comparative Example 1, the PVAc / OMMT latex film prepared in Comparative Example 3, and the PVAc / OMMT / PKH570 latex film prepared in Example 3. Detailed Implementation
[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention. It should be noted that, unless otherwise specified, all chemical reagents involved in this invention are purchased through commercial channels.
[0021] The English abbreviation and the full Chinese name used in this invention are as follows: Polyvinyl acetate (PVAc), polyvinyl alcohol (PVA), organobentonite (OMMT), sodium dodecyl sulfate (SDS), and γ-(methacryloyloxy)propyltrimethoxysilane (KH570).
[0022] Preparation Example The preparation method of acrylic acid intercalation modified organobentonite includes the following steps: (1) Preparation of alkaline calcium-based bentonite In an open kettle, 450 parts of deionized water, 200 parts of activated clay, and 150 parts of calcium oxide were taken and mixed evenly by stirring. The mixture was then placed in a forced-air drying device and reacted at 70°C for 4 hours to obtain a dry product with a particle size of 1 mm. The product was transferred to an open kettle, 10 parts of distilled water were added, and the mixture was stirred to ensure thorough mixing. The mixture was then passed through a 50-mesh sieve and washed twice with 80 parts of distilled water to remove unreacted calcium hydroxide. The mixture was then dried at 90°C, pulverized, and passed through a 200-mesh sieve to obtain alkaline calcium-based bentonite. (2) Preparation of acrylic acid intercalation modified organic bentonite: In a reactor equipped with a mechanical stirrer, condenser, and temperature control device, 80 parts of prepared alkaline calcium-based bentonite and 25 parts of cyclohexane dispersant were added. 40 parts of acrylic acid, an organic modifier, were weighed and dissolved in a mixed solvent of 20 parts anhydrous ethanol and 5 parts cyclohexane. When the temperature reached 60℃ and the cyclohexane reached boiling reflux, the temperature was maintained at 60℃. After the liquid level in the separator reached reflux equilibrium, the acrylic acid solution was pumped into the reactor, with the feeding rate controlled at 0.2 parts / minute. The addition was completed within 2 hours, followed by a 3-hour reaction. After the reaction was completed, the product was transferred to a filter press. The filter cake was washed twice with a mixed solvent of 25 parts anhydrous ethanol and cyclohexane, and then dried at 60℃ to obtain acrylic acid intercalated modified organic bentonite.
[0023] Example 1 A method for preparing a KH570 composite polymer modified PVAc emulsion includes the following steps: S1. Preparation of PKH570 polymer 30 parts KH570, 15 parts ethanol, 3 parts deionized water, 0.03 parts HCl and 0.01 parts hydroquinone were added sequentially to the reaction vessel, mixed evenly, heated to 65℃, and reacted at a constant temperature for 8 hours to obtain a crude product. The crude product was then subjected to vacuum distillation at 50℃ to remove impurities such as water, ethanol, HCl and unreacted organosilicon to obtain PKH570. S2. Preparation of VAc / OMMT preemulsion Add 3 parts PVA and 90 parts deionized water to the reactor, heat to 95°C, stir until completely dissolved, cool the solution to 50°C, add 1.5 parts of acrylic acid intercalated modified organobentonite prepared in the preparation example, stir thoroughly to make it uniformly dispersed in the system, and then add 0.2 parts SDS, 0.5 parts OP-10 and 15 parts vinyl acetate VAc monomer in sequence and continue stirring for 2 hours for pre-emulsification; S3. Preparation of PVAc / OMMT / PKH570 composite emulsion Add 1 part of 10% ammonium persulfate solution to the VAc / OMMT pre-emulsion obtained in step S2, heat to 65°C, and keep the reaction temperature for 40 min. After the reaction system is refluxed, slowly add 1.5 parts of a mixture of PKH570 and 30 parts of vinyl acetate through a dropping funnel, while adding 1.5 parts of 10% ammonium persulfate solution in batches. Divide the 1.5 parts of 10% ammonium persulfate solution into 5 equal parts (0.3 parts each). Under stirring, add one part every 30 minutes. After the addition is complete, raise the temperature to 85°C and keep the reaction temperature for 40 min. After the reaction is complete, cool to 50°C, add 4 parts of dibutyl phthalate, stir evenly, and finally cool to room temperature to obtain a white emulsion, which is the PVAc / OMMT / PKH570 composite emulsion, i.e., the PVAc emulsion modified by KH570 composite polymer.
[0024] Tests showed that the latex film made from the KH570 composite polymer-modified PVAc emulsion prepared in this embodiment had a water absorption rate of 25.7% and a water-soluble content of 4.6%; a tensile strength of 21.5 MPa, an elongation at break of 385%, and an initial thermal decomposition temperature (T0). 5% The maximum decomposition temperature is 241℃. max The temperature was 342.3℃.
[0025] Example 2 A method for preparing a KH570 composite polymer modified PVAc emulsion includes the following steps: S1. Preparation of PKH570 polymer 35 parts KH570, 14 parts ethanol, 5 parts deionized water, 0.04 parts HCl and 0.012 parts hydroquinone were added sequentially to the reaction vessel, mixed evenly, heated to 70℃, and reacted at a constant temperature for 9 hours to obtain a crude product. The crude product was then subjected to vacuum distillation at 50℃ to remove impurities such as water, ethanol, HCl and unreacted organosilicon to obtain PKH570. S2. Preparation of VAc / OMMT preemulsion Add 3.5 parts PVA and 100 parts deionized water to the reactor, heat to 90°C, stir until completely dissolved, cool the solution to 50°C, add 1.5 parts of acrylic acid intercalated modified organobentonite prepared in the preparation example, stir thoroughly to make it uniformly dispersed in the system, then add 0.2 parts SDS, 0.5 parts OP-10 and 12 parts vinyl acetate VAc monomer in sequence and continue stirring for 2.5 h for pre-emulsification; S3. Preparation of PVAc / OMMT / PKH570 composite emulsion Add 1 part of 10% ammonium persulfate solution to the VAc / OMMT pre-emulsion obtained in step S2, heat to 70°C, and keep the reaction temperature for 35 min. After the reaction system is refluxed, slowly add 1.0 part of PKH570 and 25 parts of vinyl acetate mixture through a dropping funnel, while adding 1.5 parts of 10% ammonium persulfate solution in batches. Divide the 1.5 parts of 10% ammonium persulfate solution into 5 equal parts (0.3 parts each). Under stirring, add one part every 30 minutes. After the addition is complete, raise the temperature to 80°C and keep the reaction temperature for 30 min. After the reaction is complete, cool to 50°C, add 4 parts of dibutyl phthalate, stir evenly, and finally cool to room temperature to obtain a white emulsion, which is the PVAc / OMMT / PKH570 composite emulsion, i.e., the PVAc emulsion modified by KH570 composite polymer.
[0026] Tests showed that the latex film prepared from the KH570 composite polymer-modified PVAc emulsion in this embodiment had a water absorption rate of 26.8%, a water-soluble content of 4.6%, and an initial decomposition temperature (T). 5% The maximum decomposition temperature (T) is 262.7℃. max The temperature was 348.9℃, the tensile strength was 24.1MPa, and the elongation at break was 405%.
[0027] Example 3 A method for preparing a KH570 composite polymer modified PVAc emulsion includes the following steps: S1. Preparation of PKH570 polymer 40 parts KH570, 15 parts ethanol, 6 parts deionized water, 0.03 parts HCl and 0.012 parts hydroquinone were added sequentially to the reaction vessel, mixed evenly, heated to 70℃, and reacted at a constant temperature for 10 hours to obtain a crude product. The crude product was then subjected to vacuum distillation at 50℃ to remove impurities such as water, ethanol, HCl and unreacted organosilicon to obtain PKH570. S2. Preparation of VAc / OMMT preemulsion Add 4 parts PVA and 110 parts deionized water to the reactor, heat to 95°C, stir until completely dissolved, cool the solution to 50°C, add 1.5 parts of acrylic acid intercalated modified organobentonite prepared in the preparation example, stir thoroughly to make it uniformly dispersed in the system, and then add 0.2 parts SDS, 0.5 parts OP-10 and 16 parts vinyl acetate VAc monomer in sequence and continue stirring for 3 hours for pre-emulsification; S3. Preparation of PVAc / OMMT / PKH570 composite emulsion Add 1 part of 10% ammonium persulfate solution to the VAc / OMMT pre-emulsion obtained in step S2, heat to 75°C, and keep the reaction temperature for 40 min. After the reaction system is refluxed, slowly add 1.0 part of PKH570 and 24 parts of vinyl acetate mixture through a dropping funnel, while adding 1.5 parts of 10% ammonium persulfate solution in batches. Divide the 1.5 parts of 10% ammonium persulfate solution into 5 equal parts (0.3 parts each). Under stirring, add one part every 30 minutes. After the addition is complete, raise the temperature to 85°C and keep the reaction temperature for 40 min. After the reaction is completed, cool to 50°C, add 4 parts of dibutyl phthalate, stir evenly, and finally cool to room temperature to obtain a white emulsion, which is the PVAc / OMMT / PKH570 composite emulsion, i.e., the PVAc emulsion modified by KH570 composite polymer.
[0028] Depend on Figure 1 It can be seen that the characteristic absorption peak of the PKH570 polymer appears in the spectrum, at 3385 cm⁻¹. -1 The peak at this point is the stretching vibration peak of -OH, located between 2953 and 2893 cm⁻¹. -1 The peak at 1715 cm⁻¹ represents the stretching vibration of methyl and methylene groups. -1 The strong absorption peak at 1635 cm⁻¹ is caused by the stretching vibration of the ester carbonyl group. -1 The peak at 1296 cm⁻¹ is a characteristic peak of C=C, while the peak at 1296 cm⁻¹ is a characteristic peak of C=C. -1 The peak at 1120–1000 cm⁻¹ is a characteristic peak for Si-C. -1 The peak at this point is the antisymmetric stretching vibration peak of Si-O, indicating that KH570 underwent hydrolysis and condensation to obtain an organosilicon polymer, proving the successful synthesis of PKH570.
[0029] According to the test, the latex film made from the KH570 composite polymer modified PVAc emulsion prepared in this embodiment has a water absorption rate of 30.5% and a water-soluble content of 4.5%.
[0030] Depend on Figure 2 It can be seen that the thermal weight loss rate of the latex film prepared by the PVAc / OMMT / PKH570 emulsion and the initial decomposition temperature (T) are related. 5% The maximum decomposition temperature is 298.5℃. max The initial decomposition temperature was 352.3℃, which was significantly higher than that of the latex film prepared by pure PVAc emulsion and PVAc / PKH570 emulsion. This indicates that the synergistic modification of OMMT and PKH570 significantly improved the thermal stability.
[0031] Depend on Figure 3 It can be seen that the latex film prepared by the PVAc emulsion modified by the KH570 composite polymer prepared in this embodiment has a tensile strength of 24.9 MPa and an elongation at break of 417%. The tensile strength of the latex film prepared by the PVAc / OMMT / PKH570 emulsion is much higher than that of the latex film prepared by the pure PVAc emulsion and the PVAc / OMMT emulsion, indicating that the synergistic modification of OMMT and PKH570 significantly improves the mechanical properties.
[0032] Example 4 A method for preparing a KH570 composite polymer modified PVAc emulsion includes the following steps: S1. Preparation of PKH570 polymer 37 parts KH570, 15 parts ethanol, 6 parts deionized water, 0.04 parts HCl and 0.013 parts hydroquinone were added sequentially to the reaction vessel, mixed evenly, heated to 75°C, and reacted at a constant temperature for 10 hours to obtain a crude product. The crude product was then subjected to vacuum distillation at 50°C to remove impurities such as water, ethanol, HCl and unreacted organosilicon to obtain PKH570. S2. Preparation of VAc / OMMT preemulsion Add 4.7 parts PVA and 115 parts deionized water to the reactor, heat to 95°C, stir until completely dissolved, cool the solution to 50°C, add 1.5 parts of acrylic acid intercalated modified organobentonite prepared in the preparation example, stir thoroughly to make it uniformly dispersed in the system, and then add 0.2 parts SDS, 0.5 parts OP-10 and 17 parts vinyl acetate VAc monomer in sequence and continue stirring for 2.5 h for pre-emulsification; S3. Preparation of PVAc / OMMT / PKH570 composite emulsion Add 1 part of 10% ammonium persulfate solution to the VAc / OMMT pre-emulsion obtained in step S2, heat to 75°C, and keep the reaction temperature for 40 min. After the reaction system is refluxed, slowly add 1.0 part of PKH570 and 23 parts of vinyl acetate mixture through a dropping funnel, while adding 1.5 parts of 10% ammonium persulfate solution in batches. Divide the 1.5 parts of 10% ammonium persulfate solution into 5 equal parts (0.3 parts each). Under stirring, add one part every 30 minutes. After the addition is complete, raise the temperature to 85°C and keep the reaction temperature for 40 min. After the reaction is completed, cool to 50°C, add 4 parts of dibutyl phthalate, stir evenly, and finally cool to room temperature to obtain a white emulsion, which is the PVAc / OMMT / PKH570 composite emulsion, that is, the PVAc emulsion modified by KH570 composite polymer.
[0033] Tests showed that the latex film made from the KH570 composite polymer-modified PVAc emulsion prepared in this embodiment had a water absorption rate of 33.9%, a water-soluble content of 4.2%, a tensile strength of 22.8 MPa, an elongation at break of 395%, and an initial decomposition temperature (T0). 5% The maximum decomposition temperature is 286.4℃. max The temperature was 345.1℃.
[0034] Comparative Example 1 A method for preparing pure PVAc emulsion includes the following steps: Add 3.5 parts PVA and 100 parts deionized water to a reaction vessel, heat to 95°C, and stir until completely dissolved. After cooling the solution to 50°C, add 0.2 parts SDS, 0.5 parts OP-10, and 15 parts vinyl acetate (VAc) monomer sequentially and continue stirring for 2 hours for pre-emulsification. Then add 1 part of 10% ammonium persulfate solution, heat to 75°C, and keep the reaction temperature for 30 minutes. After the reaction system is refluxed, slowly add 25 parts of vinyl acetate solution through a dropping funnel, while adding 1.5 parts of 10% ammonium persulfate solution in batches. Divide the 1.5 parts of 10% ammonium persulfate solution into 5 equal parts (0.3 parts each). Under stirring, add one part every 30 minutes. After the addition is complete, raise the temperature to 85°C and keep the reaction temperature for 40 minutes. After the reaction is complete, cool to 50°C, add 4 parts of dibutyl phthalate, stir evenly, and finally cool to room temperature to obtain a white emulsion, which is a pure PVAc emulsion.
[0035] This comparative example did not modify the PVAc emulsion.
[0036] Tests showed that the latex film made from the pure PVAc emulsion prepared in this comparative example had a water absorption rate of 71.5%, a water-soluble content of 7.5%, a tensile strength of 7.6 MPa, an elongation at break of 236%, and an initial decomposition temperature (T0). 5%The maximum decomposition temperature is 258℃ (T). max The temperature is 336℃.
[0037] Comparative Example 2 A method for preparing a KH570 composite polymer modified PVAc emulsion includes the following steps: Add 3.5 parts PVA and 100 parts deionized water to the reactor, heat to 95°C, and stir until completely dissolved. Cool the solution to 50°C, then add 0.2 parts SDS, 0.5 parts OP-10, and 16 parts vinyl acetate (VAc) monomer sequentially, and continue stirring for 3 minutes. Pre-emulsification was performed; then 1 part of 10% ammonium persulfate solution was added, heated to 75℃, and kept at this temperature for 40 min. After the reaction system was refluxed, 1.5 parts of a mixture of PKH570 and 24 parts of vinyl acetate were slowly added dropwise through a dropping funnel, while 1.5 parts of 10% ammonium persulfate solution were added in batches. The 1.5 parts of 10% ammonium persulfate solution was divided into 5 equal parts (0.3 parts each). Under stirring, one part was added every 30 minutes. After the addition was completed, the temperature was raised to 85℃ and kept at this temperature for 40 min. After the reaction was completed, the temperature was cooled to 50℃, 4 parts of dibutyl phthalate were added, and the mixture was stirred evenly. Finally, the temperature was cooled to room temperature to obtain a white emulsion, which is the PVAc emulsion modified by KH570 composite polymer.
[0038] This comparative example did not contain acrylic-intercalated modified organobentonite.
[0039] Tests showed that the latex film prepared from the PVAc / PKH570 composite emulsion in this comparative example had a water absorption rate of 60%, a water-soluble content of 3.8%, a tensile strength of 14.5 MPa, an elongation at break of 223%, and an initial decomposition temperature (T0). 5% The maximum decomposition temperature is 294℃. max The temperature is 321℃.
[0040] Comparative Example 3 A method for preparing an OMMT-modified PVAc emulsion includes the following steps: Add 3.5 parts PVA and 100 parts deionized water to a reactor, heat to 95°C, and stir until completely dissolved. After cooling the solution to 50°C, add 1.5 parts of the acrylic acid intercalated modified organobentonite prepared in the preparation example, and stir thoroughly to ensure uniform dispersion in the system. Then, add 0.2 parts SDS, 0.5 parts OP-10, and 16 parts vinyl acetate (VAc) monomer sequentially, and continue stirring for 3 minutes. Pre-emulsification was performed; then 1 part of 10% ammonium persulfate solution was added, heated to 75°C, and kept at this temperature for 40 minutes. After the reaction system was refluxed, 24 parts of vinyl acetate solution were slowly added dropwise through a dropping funnel, while 1.5 parts of 10% ammonium persulfate solution were added in batches. The 1.5 parts of 10% ammonium persulfate solution was divided into 5 equal parts (0.3 parts each). Under stirring, one part was added every 30 minutes. After the addition was completed, the temperature was raised to 85°C and kept at this temperature for 40 minutes. After the reaction was completed, the temperature was cooled to 50°C, 4 parts of dibutyl phthalate were added, and the mixture was stirred evenly. Finally, the mixture was cooled to room temperature to obtain a white emulsion, which is the PVAc / OMMT composite emulsion.
[0041] This comparative example did not include PKH570.
[0042] Tests showed that the latex film prepared from the PVAc / OMMT composite emulsion in this comparative example had a water absorption rate of 71%, a water-soluble content of 7.3%, a tensile strength of 7.6 MPa, an elongation at break of 309%, and an initial decomposition temperature (T0). 5% The maximum decomposition temperature is 270℃ (T). max The temperature was 349℃.
[0043] Comparative Example 4 A method for preparing a KH570 modified PVAc emulsion includes the following steps: Add 3.5 parts PVA and 100 parts deionized water to a reactor, heat to 95°C, and stir until completely dissolved. After cooling the solution to 50°C, add 1.5 parts of the acrylic acid intercalated modified organobentonite prepared in the preparation example, and stir thoroughly to ensure uniform dispersion in the system. Then, add 0.2 parts SDS, 0.5 parts OP-10, and 16 parts vinyl acetate (VAc) monomer sequentially, and continue stirring for 3 minutes. Pre-emulsification was performed; then 1 part of 10% ammonium persulfate solution was added, heated to 75℃, and kept at this temperature for 40 min. After the reaction system was refluxed, 1.5 parts of a mixture of KH570 and 24 parts of vinyl acetate was slowly added dropwise through a dropping funnel, while 1.5 parts of 10% ammonium persulfate solution were added in batches. The 1.5 parts of 10% ammonium persulfate solution was divided into 5 equal parts (0.3 parts each). Under stirring, one part was added every 30 minutes. After the addition was completed, the temperature was raised to 85℃ and kept at this temperature for 40 min. After the reaction was completed, the temperature was cooled to 50℃, 4 parts of dibutyl phthalate were added, and the mixture was stirred evenly. Finally, the temperature was cooled to room temperature to obtain a white emulsion, which is the PVAc / OMMT / KH570 composite emulsion.
[0044] This comparative example did not modify KH570.
[0045] Tests showed that the latex film prepared from the PVAc / OMMT / KH570 composite emulsion prepared in the comparative example had a water absorption rate of 25.8%, a water-soluble content of 3.5%, a tensile strength of 11.4 MPa, an elongation at break of 370%, and an initial decomposition temperature (T0). 5% The maximum decomposition temperature is 269℃. max The temperature is 287℃.
[0046] Performance testing The emulsions prepared in the above embodiments and comparative examples were used to prepare latex films by coating film formation method. The performance of the latex films was tested, and the results are shown in Table 1.
[0047] 1. Water resistance test The water resistance of the film is characterized by water absorption rate and water-soluble content. The test method is as follows: accurately weigh the mass M0 of the glass plate (100 mm × 50 mm), evenly coat the emulsion on the glass plate, dry it and weigh it, and record it as M1. Place it in a water bath at 30℃ (the water in the water bath is distilled water) and soak for 24 h. Take it out, gently wipe the water on the surface with filter paper and weigh it as M2. Then place it in a desiccator and place it for 24 h and accurately weigh it as M3.
[0048] Water absorption rate: R(%)=(M2-M1) / (M1-M0).
[0049] Water-soluble content: T(%) = (M1 - M3) / (M1 - M0) 2. Tensile property test The film was cut into 150 mm × 10 mm samples for tensile property testing. The effective measurement length was 60 mm, and each sample was measured five times and the average value was calculated. The tensile strength and elongation at break of the samples were measured using an INSTRON 3366 electronic universal testing machine at a testing speed of 50 mm / min.
[0050] 3. Thermogravimetric test Thermal stability tests were performed on the samples using a Netzsch STA449F3 thermal analyzer (Germany). Temperature range: 50–600 °C; heating rate: 10 °C / min; atmosphere: high-purity nitrogen.
[0051] 4. Infrared spectroscopy test The infrared spectra of the radicals were determined using a Shimadzu IRAffinity-1 infrared spectrometer (Japan), with a scan range of 400-4000 cm⁻¹. -1 The resolution is 4 cm. −1 Table 1 Performance Test Results In summary, this invention successfully prepared a PVAc composite emulsion with excellent comprehensive performance through the synergistic modification of PKH570 and OMMT, effectively solving the problems of insufficient water resistance, thermal stability and mechanical properties of existing PVAc emulsions.
[0052] The present invention and its embodiments have been described above. This description is not restrictive, and the embodiments shown are only one of the embodiments of the present invention. The actual structure is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.
Claims
1. A method for preparing a KH570 composite polymer modified PVAc emulsion, characterized in that, Includes the following steps: S1. Preparation of PKH570 polymer KH570, ethanol, deionized water, hydrochloric acid and hydroquinone were added sequentially to the reaction vessel and mixed evenly to obtain a crude product. The crude product was then distilled under reduced pressure to obtain PKH570. S2. Preparation of VAc / OMMT preemulsion PVA and deionized water were added to the reactor and heated and stirred until completely dissolved. The solution was cooled and then acrylic intercalated modified organobentonite, sodium dodecyl sulfate, OP-10 and vinyl acetate were added in sequence. The mixture was stirred evenly to pre-disperse the solution and obtain VAc / OMMT pre-emulsion. S3. Preparation of PVAc / OMMT / PKH570 composite emulsion Add ammonium persulfate solution to the VAc / OMMT pre-emulsion obtained in step S2, heat to 60-80℃ and keep reacting for 30-50 minutes. Slowly add a mixture of PKH570 and vinyl acetate through a dropping funnel while adding ammonium persulfate solution. After the addition is complete, raise the temperature to 80-90℃ and keep reacting for 20-40 minutes. After the reaction is complete, cool to below 50℃, add dibutyl phthalate, stir evenly, and finally cool to room temperature to obtain PVAc / OMMT / KH570 composite emulsion, which is a PVAc emulsion modified by KH570 composite polymer.
2. The method for preparing a KH570 composite polymer modified PVAc emulsion according to claim 1, characterized in that, In step S1, the mass ratio of KH570, ethanol, deionized water, hydrochloric acid and hydroquinone is (30-40): (14-16): (3-7): (0.02-0.05): (0.008-0.015), and the concentration of hydrochloric acid is 0.1-1 mol / L.
3. The method for preparing a KH570 composite polymer modified PVAc emulsion according to claim 1, characterized in that, The reaction temperature in step S1 is 65-75℃, and the reaction time is 8-10h.
4. The method for preparing a KH570 composite polymer modified PVAc emulsion according to claim 1, characterized in that, In step S2, the mass ratio of PVA, deionized water, acrylic acid-intercalated modified organic bentonite, sodium dodecyl sulfate, OP-10 and vinyl acetate is (3-5):(90-120):1.5:0.2:0.5:(10-20).
5. The method for preparing a KH570 composite polymer modified PVAc emulsion according to claim 1, characterized in that, In step S2, the temperature is heated to 85-95℃ and cooled to below 50℃. The pre-dispersion stirring time is 2-3 hours.
6. The method for preparing a KH570 composite polymer modified PVAc emulsion according to claim 1, characterized in that, In step S3, the mass ratio of PKH570 to vinyl acetate is (0.4-2.8): (20-30).
7. A PVAc emulsion modified with KH570 composite polymer, characterized in that, It is prepared by the method for preparing a KH570 composite polymer modified PVAc emulsion according to any one of claims 1-6.