Modified hydroxypropyl methylcellulose ether for coating and its preparation method and application

Abstract

This invention discloses a modified hydroxypropyl methylcellulose ether for coatings, its preparation method, and its applications, belonging to the field of coating technology. It includes a freeze-thaw resistant and abrasion-resistant modified hydroxypropyl methylcellulose ether and an antibacterial and antistatic modified hydroxypropyl methylcellulose ether, with a mass ratio of 5-7:3-5. The modified hydroxypropyl methylcellulose ether for coatings prepared by this invention, when added to coatings, can improve the low-temperature freeze resistance, antibacterial properties, abrasion resistance, antistatic properties, and thermal conductivity of the coatings. It exhibits good dispersibility in water-based coatings, prevents sedimentation, improves brushing feel, resists sagging, results in more uniform film formation, reduces brush marks, and lowers the water absorption rate of the coating, showing broad application prospects.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a modified hydroxypropyl methylcellulose ether for coatings, its preparation method, and its application. Background Technology

[0002] Hydroxypropyl methylcellulose (HPMC) is a type of nonionic cellulose mixed ether. Unlike ionic methylcarboxymethyl cellulose mixed ethers, it does not react with heavy metals. Due to differences in the ratio of methoxy groups to hydroxypropyl groups and variations in viscosity, HPMC exhibits different properties. For example, varieties with high methoxy and low hydroxypropyl content have properties similar to methylcellulose, while varieties with low methoxy and high hydroxypropyl content have properties similar to hydroxypropylcellulose. However, even within varieties containing only small amounts of hydroxypropyl or methoxy groups, significant differences can occur in their solubility in organic solvents and their flocculation temperature in aqueous solutions.

[0003] Methylcellulose has excellent film-forming properties. Its aqueous or organic solvent solutions, when coated onto a glass plate and dried, form a colorless, transparent, and tough film. It also exhibits good moisture resistance, remaining solid even at high humidity. However, traditional HPMC has poor low-temperature film-forming properties and poor low-temperature freeze resistance. Furthermore, its preferential solubility in water affects its dispersibility in water-based coatings. Summary of the Invention

[0004] The purpose of this invention is to provide a modified hydroxypropyl methylcellulose ether for coatings, its preparation method, and its application. When added to coatings, it can improve the low-temperature freeze resistance, antibacterial properties, abrasion resistance, antistatic properties, and thermal conductivity of the coatings. It has good dispersibility in water-based coatings, prevents sedimentation, improves brushing feel, prevents sagging, forms more uniform films, reduces brush marks, and lowers the water absorption rate of the coatings, thus having broad application prospects.

[0005] The technical solution of this invention is implemented as follows:

[0006] This invention provides a modified hydroxypropyl methylcellulose ether for coatings, comprising antifreeze and abrasion resistant modified hydroxypropyl methylcellulose ether and antibacterial and antistatic modified hydroxypropyl methylcellulose ether, in a mass ratio of 5-7:3-5.

[0007] As a further improvement of the present invention, the preparation method of the antifreeze and wear-resistant modified hydroxypropyl methylcellulose ether is as follows:

[0008] S1. Preparation of branched polyester: Pentaerythritol, trimellitic anhydride and catalyst are added to N,N-dimethylformamide, and the mixture is heated and stirred under inert gas protection until the acid value remains unchanged to obtain carboxyl-terminated branched polyester.

[0009] S2. Preparation of hyperbranched modified hydroxypropyl methylcellulose ether: Carboxyl-terminated branched polyester and hydroxypropyl methylcellulose ether were added to glycidyl tert-carbonate, a catalyst was added, and the mixture was heated and stirred under inert gas protection until the acid value remained unchanged to obtain hyperbranched modified hydroxypropyl methylcellulose ether.

[0010] S3. Alkenyl hydroxyapatite modification: Hydroxyapatite, composite silane coupling agent, and hyperbranched modified hydroxypropyl methylcellulose ether are added to ethanol, heated and stirred to react, filtered, washed, and dried to obtain antifreeze and wear-resistant modified hydroxypropyl methylcellulose ether.

[0011] As a further improvement of the present invention, the molar ratio of pentaerythritol, trimellitic anhydride and catalyst in step S1 is 1:4-4.1:0.1-0.2, the catalyst is p-toluenesulfonic acid, and the temperature of the heating and stirring reaction is 130-140℃.

[0012] As a further improvement of the present invention, the mass ratio of the carboxyl-terminated branched polyester, hydroxypropyl methylcellulose ether and the catalyst in step S2 is 3-5:8-10:2-3, the catalyst is p-toluenesulfonic acid, and the temperature of the heating and stirring reaction is 140-150°C.

[0013] As a further improvement of the present invention, the composite silane coupling agent in step S3 includes a silane coupling agent with double bonds, a silane coupling agent with amino groups, and a silane coupling agent with epoxy groups, in a mass ratio of 5-7:1-2:2-3. The silane coupling agent with double bonds is selected from at least one of KH570, A151, and A171; the silane coupling agent with amino groups is selected from at least one of KH550, KH602, and KH792; the silane coupling agent with epoxy groups is KH560; the mass ratio of hydroxyapatite, the composite silane coupling agent, and the hyperbranched modified hydroxypropyl methylcellulose ether is 4-5:2-3:12-15; and the heating and stirring reaction is carried out at a temperature of 40-50°C for 3-5 hours.

[0014] As a further improvement of the present invention, the preparation method of the antibacterial and antistatic modified hydroxypropyl methylcellulose ether is as follows:

[0015] T1. Hydroxypropyl methylcellulose ether was added to N,N-dimethylformamide, epichlorohydrin was added, the mixture was heated and stirred to react, then triethylamine was added dropwise to continue the reaction, the mixture was filtered, washed, and dried to obtain quaternary ammonium salt modified hydroxypropyl methylcellulose ether.

[0016] T2. Quaternary ammonium salt modified hydroxypropyl methylcellulose ether was added to an aqueous dispersion of graphene oxide, heated and stirred to react, dialyzed, and dried to obtain antibacterial and antistatic modified hydroxypropyl methylcellulose ether.

[0017] As a further improvement of the present invention, the mass ratio of hydroxypropyl methylcellulose ether, epichlorohydrin and triethylamine in step T1 is 1:5-7:1-2, and the heating and stirring reaction temperature is 75-85°C for 1-2 hours.

[0018] As a further improvement of the present invention, the solid-liquid ratio of the quaternary ammonium salt modified hydroxypropyl methylcellulose ether and the graphene oxide aqueous dispersion in step T2 is 1:3-5 g / mL, the concentration of the graphene oxide aqueous dispersion is 1-2 mg / mL, the heating and stirring reaction temperature is 40-50℃, the time is 1-2 h, and the dialysis time is 12-24 h.

[0019] The present invention further protects a method for preparing the above-mentioned modified hydroxypropyl methylcellulose ether for coatings, wherein antifreeze and wear-resistant modified hydroxypropyl methylcellulose ether and antibacterial and antistatic modified hydroxypropyl methylcellulose ether are mixed evenly to obtain modified hydroxypropyl methylcellulose ether for coatings.

[0020] This invention further protects the application of the above-mentioned modified hydroxypropyl methylcellulose ether for coatings in improving the low-temperature freeze resistance, antibacterial properties, abrasion resistance, antistatic properties and thermal conductivity of coatings.

[0021] The present invention has the following beneficial effects:

[0022] This invention utilizes carboxyl-terminated branched polyester to modify hydroxypropyl methylcellulose ether, forming a network structure rich in carboxyl and hydroxyl groups. The presence of moisture is controlled through hydrogen bonding and electrostatic interactions, thereby improving the low-temperature performance of the modified hydroxypropyl methylcellulose ether and maintaining good film-forming properties even at low temperatures. Furthermore, under the action of a composite silane coupling agent, the aminosilane coupling agent and the epoxysilane coupling agent react with each other, promoting the formation of a stable network structure in the hydroxypropyl methylcellulose ether. This prevents sedimentation, improves the brushing feel, resists sagging, results in more uniform film formation, reduces brush marks, and allows for the modification of hydroxyapatite to obtain alkenyl hydroxyapatite, which in turn modifies the hydroxypropyl methylcellulose ether, improving its abrasion resistance and mechanical properties while reducing its water absorption.

[0023] This invention prepares an antibacterial and antistatic modified hydroxypropyl methylcellulose ether. By reacting hydroxypropyl methylcellulose ether with epichlorohydrin and then with triethylamine, quaternary ammonium salts are grafted onto the hydroxypropyl methylcellulose ether backbone, thereby improving its antibacterial properties. Furthermore, by forming hydrogen bonds with graphene oxide, the form of moisture is further controlled, improving low-temperature performance, antistatic properties, mechanical properties, and thermal conductivity.

[0024] The modified hydroxypropyl methylcellulose ether for coatings prepared by this invention can improve the low-temperature freeze resistance, antibacterial properties, wear resistance, antistatic properties and thermal conductivity of coatings. It has good dispersibility in water-based coatings, prevents sedimentation, improves brushing feel, prevents sagging, forms more uniform films, reduces brush marks, and lowers the water absorption rate of coatings, and has broad application prospects. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Graphene oxide, Xianfeng Nano, purity >99%, average thickness 5nm, average oxygen content 35%, average sheet diameter 10μm.

[0027] Preparation Example 1: Preparation of Antifreeze and Abrasion-Resistant Modified Hydroxypropyl Methylcellulose Ether

[0028] The method is as follows:

[0029] S1. Preparation of branched polyester: 0.1 mol pentaerythritol, 0.4 mol trimellitic anhydride and 0.01 mol p-toluenesulfonic acid were added to 200 mL N,N-dimethylformamide. Under nitrogen protection, the mixture was heated to 130 °C and stirred until the acid value remained unchanged to obtain carboxyl-terminated branched polyester.

[0030] S2. Preparation of hyperbranched modified hydroxypropyl methylcellulose ether: 3g of carboxyl-terminated branched polyester and 8g of hydroxypropyl methylcellulose ether were added to 150mL of glycidyl tert-carbonate and 2g of p-toluenesulfonic acid were added. Under nitrogen protection, the mixture was heated to 140℃ and stirred until the acid value remained unchanged to obtain hyperbranched modified hydroxypropyl methylcellulose ether.

[0031] S3. Alkenyl hydroxyapatite modification: 4g hydroxyapatite, 2g composite silane coupling agent, and 12g hyperbranched modified hydroxypropyl methylcellulose ether were added to 250mL ethanol, heated to 40℃, stirred for 3h, filtered, washed, and dried to obtain antifreeze and wear-resistant modified hydroxypropyl methylcellulose ether.

[0032] The composite silane coupling agent includes silane coupling agent A151, silane coupling agent KH602 and silane coupling agent KH560, with a mass ratio of 5:1:2.

[0033] Preparation Example 2: Preparation of Antifreeze and Abrasion-Resistant Modified Hydroxypropyl Methylcellulose Ether

[0034] The method is as follows:

[0035] S1. Preparation of branched polyester: 0.1 mol pentaerythritol, 0.41 mol trimellitic anhydride and 0.02 mol p-toluenesulfonic acid were added to 200 mL N,N-dimethylformamide. Under nitrogen protection, the mixture was heated to 140 °C and stirred until the acid value remained unchanged to obtain carboxyl-terminated branched polyester.

[0036] S2. Preparation of hyperbranched modified hydroxypropyl methylcellulose ether: 5g of carboxyl-terminated branched polyester and 10g of hydroxypropyl methylcellulose ether were added to 150mL of glycidyl tert-carbonate, and 3g of p-toluenesulfonic acid were added. Under nitrogen protection, the mixture was heated to 150℃ and stirred until the acid value remained unchanged to obtain hyperbranched modified hydroxypropyl methylcellulose ether.

[0037] S3. Alkenyl hydroxyapatite modification: 5g hydroxyapatite, 3g composite silane coupling agent, and 15g hyperbranched modified hydroxypropyl methylcellulose ether were added to 250mL ethanol, heated to 50℃, stirred for 5h, filtered, washed, and dried to obtain antifreeze and wear-resistant modified hydroxypropyl methylcellulose ether.

[0038] The composite silane coupling agent includes silane coupling agent A171, silane coupling agent KH792 and silane coupling agent KH560, with a mass ratio of 7:2:3.

[0039] Preparation Example 3: Preparation of Antifreeze and Wear-Resistant Modified Hydroxypropyl Methylcellulose Ether

[0040] The method is as follows:

[0041] S1. Preparation of branched polyester: 0.1 mol pentaerythritol, 0.405 mol trimellitic anhydride and 0.015 mol p-toluenesulfonic acid were added to 200 mL N,N-dimethylformamide. Under nitrogen protection, the mixture was heated to 135 °C and stirred until the acid value remained unchanged to obtain carboxyl-terminated branched polyester.

[0042] S2. Preparation of hyperbranched modified hydroxypropyl methylcellulose ether: 4g of carboxyl-terminated branched polyester and 9g of hydroxypropyl methylcellulose ether were added to 150mL of glycidyl tert-carbonate, and 2.5g of p-toluenesulfonic acid were added. Under nitrogen protection, the mixture was heated to 145℃ and stirred until the acid value remained unchanged to obtain hyperbranched modified hydroxypropyl methylcellulose ether.

[0043] S3. Alkenyl hydroxyapatite modification: 4.5g hydroxyapatite, 2.5g composite silane coupling agent, and 13.5g hyperbranched modified hydroxypropyl methylcellulose ether were added to 250mL ethanol, heated to 45℃, stirred and reacted for 4h, filtered, washed, and dried to obtain antifreeze and wear-resistant modified hydroxypropyl methylcellulose ether.

[0044] The composite silane coupling agent includes silane coupling agent KH570, silane coupling agent KH550 and silane coupling agent KH560, with a mass ratio of 6:1.5:2.5.

[0045] Comparative Preparation Example 1

[0046] The difference from preparation example 3 is that steps S1 and S2 were not performed.

[0047] Specifically as follows:

[0048] Alkenyl hydroxyapatite modification: 4.5g hydroxyapatite, 2.5g composite silane coupling agent, and 13.5g hydroxypropyl methylcellulose ether were added to 250mL ethanol, heated to 45℃, stirred and reacted for 4h, filtered, washed, and dried to obtain antifreeze and wear-resistant modified hydroxypropyl methylcellulose ether.

[0049] The composite silane coupling agent includes silane coupling agent KH570, silane coupling agent KH550 and silane coupling agent KH560, with a mass ratio of 6:1.5:2.5.

[0050] Comparative Preparation Example 2

[0051] The difference from Preparation Example 3 is that the composite silane coupling agent in step S3 only includes KH570.

[0052] Comparative preparation example 3

[0053] The difference from Preparation Example 3 is that no composite silane coupling agent was added in step S3.

[0054] Specifically as follows:

[0055] Alkenyl hydroxyapatite modification: 4.5g hydroxyapatite and 13.5g hyperbranched modified hydroxypropyl methylcellulose ether were added to 250mL ethanol, heated to 45℃, stirred for 4h, filtered, washed, and dried to obtain antifreeze and wear-resistant modified hydroxypropyl methylcellulose ether.

[0056] Comparative preparation example 4

[0057] The difference from preparation example 3 is that step S3 was not performed.

[0058] Specifically as follows:

[0059] S1. Preparation of branched polyester: 0.1 mol pentaerythritol, 0.405 mol trimellitic anhydride and 0.015 mol p-toluenesulfonic acid were added to 200 mL N,N-dimethylformamide. Under nitrogen protection, the mixture was heated to 135 °C and stirred until the acid value remained unchanged to obtain carboxyl-terminated branched polyester.

[0060] S2. Preparation of hyperbranched modified hydroxypropyl methylcellulose ether: 4g of carboxyl-terminated branched polyester and 9g of hydroxypropyl methylcellulose ether were added to 150mL of glycidyl tert-carbonate, and 2.5g of p-toluenesulfonic acid were added. Under nitrogen protection, the mixture was heated to 145℃ and stirred until the acid value remained unchanged to obtain hyperbranched modified hydroxypropyl methylcellulose ether.

[0061] Preparation Example 4: Preparation of Antibacterial and Antistatic Modified Hydroxypropyl Methylcellulose Ether

[0062] The method is as follows:

[0063] T1. Add 1g of hydroxypropyl methylcellulose ether to 12mL of N,N-dimethylformamide, add 5g of epichlorohydrin, heat to 75℃, stir and react for 1h, then add 1g of triethylamine dropwise, continue to react for 30min, filter, wash, and dry to obtain quaternary ammonium salt modified hydroxypropyl methylcellulose ether.

[0064] T2. Add 1g of quaternary ammonium salt modified hydroxypropyl methylcellulose ether to 3mL of 1mg / mL graphene oxide aqueous dispersion, heat to 40℃, stir and react for 1h, dialyze through a dialysis bag with a pore size of 5000Da for 12h, and dry to obtain antibacterial and antistatic modified hydroxypropyl methylcellulose ether.

[0065] Preparation Example 5: Preparation of Antibacterial and Antistatic Modified Hydroxypropyl Methylcellulose Ether

[0066] The method is as follows:

[0067] T1. Add 1g of hydroxypropyl methylcellulose ether to 12mL of N,N-dimethylformamide, add 7g of epichlorohydrin, heat to 85℃, stir and react for 2h, then add 2g of triethylamine dropwise, continue to react for 60min, filter, wash, and dry to obtain quaternary ammonium salt modified hydroxypropyl methylcellulose ether.

[0068] T2. Add 1g of quaternary ammonium salt modified hydroxypropyl methylcellulose ether to 5mL of 2mg / mL graphene oxide aqueous dispersion, heat to 50℃, stir and react for 2h, dialyze through a dialysis bag with a pore size of 5000Da for 24h, and dry to obtain antibacterial and antistatic modified hydroxypropyl methylcellulose ether.

[0069] Preparation Example 6: Preparation of Antibacterial and Antistatic Modified Hydroxypropyl Methylcellulose Ether

[0070] The method is as follows:

[0071] T1. Add 1g of hydroxypropyl methylcellulose ether to 12mL of N,N-dimethylformamide, add 6g of epichlorohydrin, heat to 80℃, stir and react for 1.5h, then add 1.5g of triethylamine dropwise, continue to react for 45min, filter, wash, and dry to obtain quaternary ammonium salt modified hydroxypropyl methylcellulose ether.

[0072] T2. Add 1g of quaternary ammonium salt modified hydroxypropyl methylcellulose ether to 4mL of 1.5mg / mL graphene oxide aqueous dispersion, heat to 45℃, stir and react for 1.5h, dialyze through a dialysis bag with a pore size of 5000Da for 18h, and dry to obtain antibacterial and antistatic modified hydroxypropyl methylcellulose ether.

[0073] Comparative preparation example 5

[0074] The difference from preparation example 6 is that step T1 was not performed.

[0075] Specifically, 1g of hydroxypropyl methylcellulose ether was added to 4mL of 1.5mg / mL graphene oxide aqueous dispersion, heated to 45℃, stirred for 1.5h, dialyzed for 18h using a dialysis bag with a pore size of 5000Da, and dried to obtain antibacterial and antistatic modified hydroxypropyl methylcellulose ether.

[0076] Comparative preparation example 6

[0077] The difference compared to preparation example 3 is that step T2 was not performed.

[0078] Specifically, 1g of hydroxypropyl methylcellulose ether was added to 12mL of N,N-dimethylformamide, 6g of epichlorohydrin was added, the mixture was heated to 80℃ and stirred for 1.5h, then 1.5g of triethylamine was added dropwise and the reaction was continued for 45min. The mixture was then filtered, washed, and dried to obtain quaternary ammonium salt modified hydroxypropyl methylcellulose ether. Example

[0079] This embodiment provides a modified hydroxypropyl methylcellulose ether for coatings, comprising the following steps:

[0080] 5g of the antifreeze and wear-resistant modified hydroxypropyl methylcellulose ether prepared in Preparation Example 1 and 3g of the antibacterial and antistatic modified hydroxypropyl methylcellulose ether prepared in Preparation Example 4 were mixed evenly to obtain modified hydroxypropyl methylcellulose ether for coatings. Example

[0081] This embodiment provides a modified hydroxypropyl methylcellulose ether for coatings, comprising the following steps:

[0082] 7g of the antifreeze and wear-resistant modified hydroxypropyl methylcellulose ether prepared in Preparation Example 2 and 5g of the antibacterial and antistatic modified hydroxypropyl methylcellulose ether prepared in Preparation Example 5 were mixed evenly to obtain modified hydroxypropyl methylcellulose ether for coatings. Example

[0083] This embodiment provides a modified hydroxypropyl methylcellulose ether for coatings, comprising the following steps:

[0084] 6g of the antifreeze and wear-resistant modified hydroxypropyl methylcellulose ether prepared in Preparation Example 3 and 4g of the antibacterial and antistatic modified hydroxypropyl methylcellulose ether prepared in Preparation Example 6 were mixed evenly to obtain modified hydroxypropyl methylcellulose ether for coatings.

[0085] Comparative Example 1

[0086] The difference from Example 3 is that the antifreeze and abrasion-resistant modified hydroxypropyl methylcellulose ether was replaced by the product obtained in Comparative Preparation Example 1.

[0087] Comparative Example 2

[0088] The difference from Example 3 is that the antifreeze and abrasion-resistant modified hydroxypropyl methylcellulose ether was replaced by the product obtained in Comparative Preparation Example 2.

[0089] Comparative Example 3

[0090] The difference from Example 3 is that the antifreeze and abrasion-resistant modified hydroxypropyl methylcellulose ether was replaced by the product obtained in Comparative Preparation Example 3.

[0091] Comparative Example 4

[0092] The difference from Example 3 is that the antifreeze and abrasion-resistant modified hydroxypropyl methylcellulose ether was replaced by the product obtained in Comparative Preparation Example 4.

[0093] Comparative Example 5

[0094] The difference from Example 3 is that the antibacterial and antistatic modified hydroxypropyl methylcellulose ether was replaced by the product obtained in Comparative Preparation Example 5.

[0095] Comparative Example 6

[0096] The difference from Example 3 is that the antibacterial and antistatic modified hydroxypropyl methylcellulose ether was replaced by the product obtained in Comparative Preparation Example 6.

[0097] Comparative Example 7

[0098] The difference compared to Example 3 is that no antifreeze and abrasion-resistant modified hydroxypropyl methylcellulose ether was added.

[0099] Comparative Example 8

[0100] The difference compared to Example 3 is that no antibacterial and antistatic modified hydroxypropyl methylcellulose ether was added.

[0101] Test Example 1

[0102] The modified hydroxypropyl methylcellulose ethers prepared in Examples 1-3 or Comparative Examples 1-8 were added to the water-based coatings at an amount of 7 wt%.

[0103] The composition of water-based coatings is as follows:

[0104] It includes component A and component B, with a mass ratio of 100:15.

[0105] Component A is prepared from the following raw materials in parts by weight: 25 parts epoxy resin 6520, 0.5 parts water-based dispersant 5040, 0.5 parts water-based defoamer BYK-017, 5 parts titanium dioxide, 10 parts talc, 0.3 parts water-based wetting agent BYK180, and 35 parts water.

[0106] Component B is a triethylenediamine curing agent.

[0107] The coating was uniformly applied to the PET film, with the wet film thickness controlled to be within 50µm. After baking and curing, the performance was tested.

[0108] The thermal conductivity of the coating was determined according to ISO 22007-2-2008.

[0109] The abrasion resistance of the coating was tested according to GB / T 1768-2006, under test conditions of 750g / 500r.

[0110] The adhesion of the coating was tested according to GB / T5210-2006 (pull-off method).

[0111] The impact resistance of the coating was tested according to GB / T 1732-2020.

[0112] According to JG / T 25-1999, the freeze-thaw cycle performance of the coating is tested. One cycle consists of -60℃ for 4 hours, room temperature for 2 hours, 50℃ for 4 hours, and room temperature for 2 hours. Ten cycles are performed.

[0113] The results are shown in Table 1.

[0114] Table 1

[0115]

[0116] According to GB / T21866-2008, the antibacterial properties of the coating were tested using Escherichia coli ATCC25922 and Staphylococcus aureus ATCC25923.

[0117] According to MT113-1995, the antistatic properties of the coating are tested, and the test value is based on the specific resistance, taking the average value of 10 tests.

[0118] According to HG / T1733-1993, the water resistance of the coating is tested by immersion in distilled water at 60℃ for 30 days.

[0119] The results are shown in Table 2.

[0120] Table 2

[0121]

[0122] As can be seen from the table above, the modified hydroxypropyl methylcellulose ethers prepared in Examples 1-3 of this invention, when added to water-based coatings, produce coatings with good overall performance.

[0123] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A modified hydroxypropyl methylcellulose ether for coatings, characterized in that, It includes antifreeze and wear-resistant modified hydroxypropyl methylcellulose ether and antibacterial and antistatic modified hydroxypropyl methylcellulose ether, with a mass ratio of 5-7:3-5; The preparation method of the antifreeze and wear-resistant modified hydroxypropyl methylcellulose ether is as follows: S1. Preparation of branched polyester: Pentaerythritol, trimellitic anhydride and catalyst are added to N,N-dimethylformamide, and the mixture is heated and stirred under inert gas protection until the acid value remains unchanged to obtain carboxyl-terminated branched polyester. S2. Preparation of hyperbranched modified hydroxypropyl methylcellulose ether: Carboxyl-terminated branched polyester and hydroxypropyl methylcellulose ether were added to glycidyl tert-carbonate, a catalyst was added, and the mixture was heated and stirred under inert gas protection until the acid value remained unchanged to obtain hyperbranched modified hydroxypropyl methylcellulose ether. S3. Alkenyl hydroxyapatite modification: Hydroxyapatite, a composite silane coupling agent, and hyperbranched modified hydroxypropyl methylcellulose ether are added to ethanol, heated and stirred to react, filtered, washed, and dried to obtain antifreeze and wear-resistant modified hydroxypropyl methylcellulose ether; the composite silane coupling agent includes silane coupling agents with double bonds, silane coupling agents with amino groups, and silane coupling agents with epoxy groups, in a mass ratio of 5-7:1-2:2-3, wherein the silane coupling agent with double bonds is selected from K At least one of H570, A151, and A171; the amino-containing silane coupling agent is selected from at least one of KH550, KH602, and KH792; the epoxy-containing silane coupling agent is KH560; the mass ratio of hydroxyapatite, composite silane coupling agent, and hyperbranched modified hydroxypropyl methylcellulose ether is 4-5:2-3:12-15; the heating and stirring reaction temperature is 40-50℃, and the time is 3-5h. The preparation method of the antibacterial and antistatic modified hydroxypropyl methylcellulose ether is as follows: T1. Hydroxypropyl methylcellulose ether was added to N,N-dimethylformamide, epichlorohydrin was added, the mixture was heated and stirred to react, then triethylamine was added dropwise to continue the reaction, the mixture was filtered, washed, and dried to obtain quaternary ammonium salt modified hydroxypropyl methylcellulose ether. T2. Quaternary ammonium salt modified hydroxypropyl methylcellulose ether was added to an aqueous dispersion of graphene oxide, heated and stirred to react, dialyzed, and dried to obtain antibacterial and antistatic modified hydroxypropyl methylcellulose ether.

2. The modified hydroxypropyl methylcellulose ether for coatings according to claim 1, characterized in that, In step S1, the molar ratio of pentaerythritol, trimellitic anhydride, and catalyst is 1:4-4.1:0.1-0.2, the catalyst is p-toluenesulfonic acid, and the temperature of the heating and stirring reaction is 130-140℃.

3. The modified hydroxypropyl methylcellulose ether for coatings according to claim 1, characterized in that, In step S2, the mass ratio of the terminal carboxyl branched polyester, hydroxypropyl methylcellulose ether, and catalyst is 3-5:8-10:2-3, the catalyst is p-toluenesulfonic acid, and the temperature of the heating and stirring reaction is 140-150℃.

4. The modified hydroxypropyl methylcellulose ether for coatings according to claim 1, characterized in that, In step T1, the mass ratio of hydroxypropyl methylcellulose ether, epichlorohydrin, and triethylamine is 1:5-7:1-2, and the heating and stirring reaction is carried out at a temperature of 75-85°C for 1-2 hours.

5. The modified hydroxypropyl methylcellulose ether for coatings according to claim 1, characterized in that, In step T2, the solid-liquid ratio of the quaternary ammonium salt modified hydroxypropyl methylcellulose ether and the graphene oxide aqueous dispersion is 1:3-5 g / mL, the concentration of the graphene oxide aqueous dispersion is 1-2 mg / mL, the heating and stirring reaction temperature is 40-50℃, the time is 1-2 h, and the dialysis time is 12-24 h.

6. A method for preparing a modified hydroxypropyl methylcellulose ether for coatings as described in any one of claims 1-5, characterized in that, Antifreeze-resistant and wear-resistant modified hydroxypropyl methylcellulose ether and antibacterial and antistatic modified hydroxypropyl methylcellulose ether are mixed evenly to obtain modified hydroxypropyl methylcellulose ether for coatings.

7. The application of a modified hydroxypropyl methylcellulose ether for coatings as described in any one of claims 1-5 in improving the low-temperature freeze resistance, antibacterial properties, abrasion resistance, antistatic properties and thermal conductivity of coatings.

Images