Lactate methacrylate monomer, bio-based acrylic resin, and preparation methods and applications of lactate methacrylate monomer and bio-based acrylic resin

Abstract

The invention discloses a methacrylate lactate monomer, bio-based acrylic resin and preparation methods and applications of the methacrylate lactate monomer and the bio-based acrylic resin, and belongs to the technical field of resin. The preparation method comprises the following steps: uniformly mixing lactic acid, glycidyl methacrylate, a polymerization inhibitor and a catalyst, wherein the molar ratio of lactic acid to glycidyl methacrylate is (0.9-1.1): 1; the preparation method comprises the following steps of: heating to 60-90 DEG C under the protection of inert gas, stirring and reacting for 4-10 hours to obtain a methacrylate lactate monomer, and preparing acrylic resin by utilizing the methacrylate lactate monomer, so that the acrylic resin has good rigidity, adhesive force and potential degradability.

Description

Technical Field

[0001] This invention belongs to the field of resin technology, and more specifically, relates to a methacrylate lactate monomer, a bio-based acrylic resin, and their preparation methods and applications. Background Technology

[0002] Acrylic resins are widely used in coatings, inks, adhesives, and other fields due to their excellent weather resistance, transparency, film-forming properties, and mechanical properties. However, the synthesis of traditional acrylic resins heavily relies on petroleum-based raw materials, such as methyl methacrylate and ethyl methacrylate. With the increasing depletion of petroleum resources and growing environmental awareness, the development of renewable and bio-based acrylic resins has become an important direction for the industry.

[0003] Lactic acid is an important bio-based platform compound that can be obtained through the fermentation of biomass raw materials such as starch and cellulose. It is abundant and completely renewable. Introducing lactic acid molecules into polymer chains is an effective way to prepare bio-based resins.

[0004] Currently, some studies have attempted to synthesize (meth)acrylate lactate by direct esterification of lactic acid with (meth)acrylic acid. However, this method has the following drawbacks: (1) Harsh reaction conditions: High temperature and high vacuum are required to remove the generated water and drive the reaction to equilibrium, resulting in high energy consumption; (2) Severe side reactions: The carboxyl and hydroxyl groups in lactic acid molecules are prone to intermolecular esterification at high temperatures, forming oligomers, which leads to a decrease in product purity, darkening of color, and yellowing. (3) Low yield: Due to the presence of side reactions and the limitation of reaction equilibrium, the yield of the target product is usually not ideal.

[0005] Therefore, there is an urgent need to develop a method for synthesizing bio-based (meth)acrylate monomers with mild conditions, few side reactions, and high yield, and to further apply it to the preparation of high-performance bio-based acrylic resins. Summary of the Invention

[0006] 1. The problem to be solved To address the problem of the harsh synthesis conditions of existing methacrylate lactate synthesis, the primary objective of this invention is to provide a method for preparing methacrylate lactate monomer; A second objective of the present invention is to provide a methacrylate lactate monomer prepared by the above-described preparation method; A third objective of this invention is to provide a method for preparing bio-based acrylic resins using the above-described methacrylate lactate monomer; A fourth objective of this invention is to provide applications of the aforementioned bio-based acrylic resin.

[0007] 2. Technical Solution To solve the above problems, the technical solution adopted by the present invention is as follows: The first aspect of this invention provides a method for preparing a methacrylate lactate (MALA) monomer, comprising the following raw materials: Lactic acid (LA) and glycidyl methacrylate (GMA) in a molar ratio of (0.9~1.1):1. Including the following steps: Step S1. Mixing: Mix lactic acid, glycidyl methacrylate, polymerization inhibitor and catalyst evenly; Step S2. Reaction: Under inert gas protection, the reaction mixture obtained in step S1 is heated to 60~90℃ and stirred for 4~10 hours; Step S3. Cool to room temperature, then purify to obtain methacrylate lactate monomer.

[0008] This invention employs an epoxy ring-opening esterification reaction of lactic acid and glycidyl methacrylate, replacing the traditional direct esterification of methacrylic acid and lactic acid. This reaction does not require high temperature and high pressure, and the conditions are mild, avoiding high-temperature self-polymerization and oxidative yellowing of lactic acid. The resulting product has a light color and high purity. Furthermore, the ring-opening reaction has high atom utilization, no small molecule byproducts (such as water) are generated, and the reaction conversion rate is high.

[0009] According to any embodiment of the first aspect of the present invention, the lactic acid is one or more of L-lactic acid, D-lactic acid or DL-lactic acid.

[0010] According to any embodiment of the first aspect of the present invention, the polymerization inhibitor is one or more of hydroquinone, p-hydroxyanisole, and 2,6-di-tert-butyl-p-cresol, and the amount of polymerization inhibitor added is 0.1% to 1% of the total mass of the reactants, wherein the total mass of the reactants is the sum of the masses of lactic acid, glycidyl methacrylate, polymerization inhibitor, and catalyst.

[0011] According to any embodiment of the first aspect of the present invention, the catalyst is one or more of triethylamine, triphenylphosphine, tetrabutylammonium bromide, chromium chloride, and stannous octoate, and the amount of catalyst added is 0.5% to 3% of the total mass of the reactants, wherein the total mass of the reactants is the sum of the masses of lactic acid, glycidyl methacrylate, polymerization inhibitor, and catalyst.

[0012] According to any embodiment of the first aspect of the present invention, the inert gas in step S2 is nitrogen or argon. According to any embodiment of the first aspect of the present invention, the post-processing purification method in step S3 includes water washing and purification: Water washing: removes the catalyst and unreacted lactic acid; Purification: Remove solvent and unreacted glycidyl methacrylate by vacuum distillation or column chromatography.

[0013] A second aspect of the present invention provides a methacrylate lactate monomer prepared by the above-described preparation method, which is obtained by polymerization of lactic acid and glycidyl methacrylate, and has the following structural formula: .

[0014] The obtained MALA monomer molecule contains two hydroxyl groups and has bifunctional characteristics, which provides sufficient cross-linking points for subsequent resins and increases the cross-linking density. It can be used to prepare thermosetting resins and improve the adhesion of resins to polar substrates. The introduction of lactic acid structural units can endow the resin with good rigidity, hardness and biodegradability potential. The polyhydroxy structure enhances the polarity and reactivity of the resin, giving the coatings made from it potential advantages in terms of adhesion and chemical resistance.

[0015] A third aspect of this invention provides a method for preparing the above-mentioned bio-based acrylic resin, employing a solution polymerization process. It includes raw materials: a) 5%~50% methacrylate lactate monomer (MALA), which is the methacrylate lactate monomer described in the second aspect of the present invention; b) 20%~95% (meth)acrylic acid comonomers; It also includes a third monomer: selected from one or more of butyl acrylate monomers, styrene monomers, or acrylonitrile monomers; The total mass of the methacrylate lactate monomer, the (meth)acrylate comonomer, and the third monomer is 100%. Including the following steps: Step 1, Preheating: Add part of the solvent and part of the initiator to the reactor and heat to a reflux temperature of 56.5~137℃; Step 2: Preparation of premix: Mix the methacrylate lactate monomer, (meth)acrylate comonomer, remaining solvent and remaining initiator evenly to prepare a premix; Step 3: Slowly add the premixed liquid obtained in Step 2 to the reactor in Step 1 over 2-4 hours. After the addition is complete, keep the mixture at a reflux temperature of 56.5-137°C for 2-6 hours. After the reaction is complete, cool to room temperature and discharge the material to obtain the bio-based acrylic resin.

[0016] According to any embodiment of the third aspect of the present invention, the (meth)acrylate comonomer includes one or more of methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hydroxyethyl (meth)acrylate, and (meth)acrylate.

[0017] According to any embodiment of the third aspect of the present invention, the initiator is one of azobisisobutyronitrile (AIBN), benzoyl peroxide (BPO), and di-tert-butyl peroxide, and its addition amount is 0.5% to 3% of the total mass of the monomers, wherein the total mass of the monomers is the sum of the masses of the methacrylate lactate monomer, the (meth)acrylate comonomer, and the third monomer.

[0018] According to any embodiment of the third aspect of the present invention, the solvent is one or more selected from toluene, xylene, ethyl acetate, butyl acetate, acetone, isopropanol, and butanol.

[0019] According to any embodiment of the third aspect of the present invention, the reflux temperature is solvent-dependent, and the reflux temperature is the boiling point of the solvent, which is related to the solvent used. For example, acetone has a minimum boiling point of 56.5°C, and xylene has a maximum boiling point of 137°C.

[0020] By adjusting the proportion of lactate methacrylate monomer in the copolymer formulation, the bio-based content of the final resin can be easily controlled, up to 50% or more, significantly reducing dependence on petroleum resources.

[0021] The fourth aspect of this invention provides the application of the above-mentioned bio-based acrylic resin in the preparation of coatings, inks, and adhesives.

[0022] 3. Beneficial effects Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The methacrylate lactate monomer of the present invention is prepared by the epoxy ring-opening reaction of bio-based lactic acid and glycidyl methacrylate. The reaction conditions are mild, avoiding the side reaction of high-temperature esterification, and the monomer product has high purity. (2) The present invention uses solution copolymerization of the methacrylate lactate monomer with conventional monomers such as (meth)acrylate to obtain an acrylic resin with high bio-based content and excellent comprehensive performance. The resin molecular chain introduces lactic acid segments and active carboxyl groups, which endows the resin with good rigidity, adhesion and potential degradability. It can be widely used in environmentally friendly coatings, inks and adhesives, etc., reducing dependence on petroleum resources. Attached Figure Description

[0023] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that these drawings are designed for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, unless specifically indicated, these drawings are intended only to conceptually illustrate the structural construction described herein and are not necessarily drawn to scale.

[0024] Figure 1The reaction equation is for the preparation of methacrylate lactate monomers from bio-based lactic acid and glycidyl methacrylate via an epoxy ring-opening reaction. Detailed Implementation

[0025] The following detailed description of exemplary embodiments of the invention is taken with reference to the accompanying drawings, which form part of the description and illustrate exemplary embodiments in which the invention may be practiced. While these exemplary embodiments have been described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be implemented and various changes may be made to the invention without departing from the spirit and scope thereof. The more detailed description of embodiments of the invention below is not intended to limit the scope of the claimed invention, but is merely illustrative and not restrictive of the description of the features and characteristics of the invention, to suggest the best mode for carrying out the invention, and is sufficient to enable those skilled in the art to practice the invention. Therefore, the scope of the invention is defined only by the appended claims.

[0026] Example 1 (1) Preparation method of methacrylate lactate monomer: Raw materials include: lactic acid and glycidyl methacrylate in a molar ratio of 1:1; Including the following steps: Step S1. Mixing: In a 250 mL three-necked flask, add 18.0 g (0.20 mol) L-lactic acid, 28.4 g (0.20 mol) glycidyl methacrylate, 0.23 g p-hydroxyanisole (MEHQ, polymerization inhibitor) and 0.70 g triethylamine (catalyst); Step S2. Reaction: Under nitrogen protection, stir and heat in an oil bath to 75°C for 6 hours; Step S3. Washing with water: After the reaction is complete, cool to room temperature, wash the reaction mixture three times with 5% sodium bicarbonate aqueous solution, then wash twice with deionized water, and collect the organic phase after separation; Purification: After drying with anhydrous magnesium sulfate, unreacted glycidyl methacrylate was removed by vacuum distillation (45°C, 1 kPa) to obtain a pale yellow transparent liquid product, lactic acid methacrylate, in a yield of 92.5%.

[0027] (2) The chemical structural formula of the methacrylate lactate monomer obtained by (1) is: .

[0028] Example 2 The preparation method of this embodiment is basically the same as that of Example 1, except that the lactic acid is D-lactic acid and the yield of the final methacrylate lactate monomer is 92.4%.

[0029] Example 3 The preparation method of this embodiment is basically the same as that of Example 1, except that the lactic acid is DL-lactic acid and the final yield of methacrylate lactate monomer is 92.8%.

[0030] Example 4 The preparation method of this embodiment is basically the same as that of Example 1, except that the molar ratio of L-lactic acid and glycidyl methacrylate is 0.9:1, and the yield of the final obtained lactic acid methacrylate monomer is 92.3%.

[0031] Example 5 The preparation method of this embodiment is basically the same as that of Example 1, except that the molar ratio of L-lactic acid and glycidyl methacrylate is 1.1:1, and the yield of the final lactic acid methacrylate monomer is 92.8%.

[0032] Example 6 In this embodiment, the content of methacrylate lactate is 20 wt%, and the raw materials for preparing the bio-based acrylic resin include: a) Methacrylate lactate monomer: 10.0 g (20 wt%), which is the methacrylate lactate monomer obtained in Example 1; b) Methyl methacrylate monomer: 30.0 g (60 wt%); Butyl acrylate (BA) monomer: 10.0 g (20 wt%); initiator azobisisobutyronitrile (AIBN): 0.75 g (1.5 wt% of total monomer mass); Solvent: Ethyl acetate: 50.0 g; Preparation methods include: Step 1: Preheating: In a 250mL four-necked flask equipped with a stirrer, condenser, thermometer and constant pressure dropping funnel, add 20g of ethyl acetate and 0.25g of azobisisobutyronitrile, and heat to 77℃ under nitrogen protection; Step 2: Preparation of premix: Mix lactate methacrylate, methyl methacrylate monomer, butyl acrylate monomer, the remaining 30g ethyl acetate and the remaining 0.5g azobisisobutyronitrile evenly to prepare a premix; Step 3: The premixed solution obtained in Step 2 is slowly added dropwise over 3 hours through a constant-pressure dropping funnel to the four-necked flask from Step 1, maintaining a reflux temperature of 77°C. After the addition is complete, the reaction is continued at the reflux temperature for another 3 hours. After the reaction is complete, the solution is cooled to below 50°C, and the product is discharged to obtain a transparent, slightly yellow, viscous resin solution A. Testing shows that the non-volatile content of this resin is 50.2%. Calculations show that the bio-based content of the resin is 7.7%. The bio-based content is the ratio of the mass of raw material lactic acid to the mass of non-volatile matter. The mass of raw material lactic acid refers to the mass of lactic acid in the raw material methacrylate lactate monomer, with a mass fraction of 18 / (18+28.4)=38.8%. In this example, the mass of lactic acid in 10.0g of methacrylate lactate monomer is 10×38.8%=3.88g. The mass of non-volatile matter refers to the mass of non-volatile matter in all raw materials. In this example, the mass of non-volatile matter in 100.75g of raw material is 100.75g×50.2%=50.5765g. Therefore, the calculated bio-based content is 3.88g / 50.5765g=7.7%.

[0033] Example 7 The raw materials for preparing the bio-based acrylic resin in this embodiment include: a) Methacrylate lactate monomer: 17.5g (35 wt%); b) Hydroxyethyl acrylate monomer: 10.0g (20 wt%); c) Styrene (St) monomer: 22.5g (45 wt%); Initiator benzoyl peroxide (BPO): 1.0 g (2 wt%); Solvent: Ethyl acetate: 50.0 g; The preparation method in this embodiment is basically the same as that in Example 6, except that the content of methacrylate lactate monomer is increased to 35 wt%, resulting in resin solution B. Testing showed that the non-volatile content of this resin was 50.4%. Calculations showed that the bio-based content of this resin was 19.3%.

[0034] Example 8 The raw materials for preparing the bio-based acrylic resin in this embodiment include: a) Methacrylate lactate monomer: 25.0g (50wt%); b) Methyl methacrylate monomer: 15.0g (30wt%); Butyl acrylate monomer: 10.0g (20wt%); Initiator azobisisobutyronitrile: 0.75g (1.5 wt% of total monomer mass); Solvent: Ethyl acetate: 50.0 g; The preparation method in this embodiment is basically the same as that in Example 6, except that the content of methacrylate lactate monomer is increased to 50%, resulting in resin solution B. Testing showed that the non-volatile content of this resin was 50.4%. Calculations showed that the bio-based content of this resin was 19.3%.

[0035] Example 9 In this embodiment, the solvent in the raw materials for preparing the bio-based acrylic resin is changed to xylene. The raw materials for preparing the bio-based acrylic resin include: Methacrylate lactate monomer: 10.0 g (20 wt%); Methyl methacrylate monomer: 30.0 g (60 wt%); Butyl acrylate monomer: 10.0 g (20 wt%); initiator azobisisobutyronitrile: 0.75 g (1.5% of the total monomer mass); Solvent xylene: 50.0g; The preparation method in this embodiment is basically the same as that in Example 6, except that the reflux temperature is 137°C, the boiling point of xylene, to obtain resin solution C. Testing showed that the non-volatile content of this resin was 50.1%. Calculations showed that the bio-based content of this resin was 7.7%.

[0036] Comparative Example 1 This comparative example illustrates the preparation of petroleum-based acrylic resin. The raw materials are essentially the same as in Example 6, except that methacrylate lactate is not used in the raw materials for this petroleum-based acrylic resin. The raw materials for preparing this acrylic resin include: Methyl methacrylate monomer: 40.0g (80 wt%); Butyl acrylate monomer: 10.0g (20 wt%); Initiator azobisisobutyronitrile: 0.75g (1.5% of the total monomer mass); Solvent: Ethyl acetate: 50.0 g; The preparation method of Comparative Example 1 was basically the same as that of Example 6, yielding resin solution D. Testing showed that the non-volatile content of this resin was approximately 50.2%. Calculations indicated that the bio-based content of this resin was 0.

[0037] Performance testing The resin solutions obtained in Examples 6-10 and Comparative Example 1 were respectively coated onto tinplate, leveled at room temperature, and cured in an 80°C oven for 1 hour to form a dry film coating with a thickness of 40 micrometers. The performance of the dry film coating was tested, and the results are shown in the table below: Table 1. Dry film performance test results of the embodiments and comparative examples of the present invention.

[0038] Test results show that the bio-based acrylic resin prepared by this invention is superior to or equivalent to traditional petroleum-based resin in terms of hardness, adhesion and chemical resistance. It has excellent comprehensive performance and can be fully used in high-performance coatings and inks.

[0039] The above description is merely a preferred embodiment of this application and an explanation of the technical principles used. Those skilled in the art should understand that the scope involved in this application is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalent features without departing from the inventive concept. For example, technical solutions formed by replacing the above-mentioned features with technical features with similar functions disclosed in this application (but not limited to) each other.

[0040] Apart from the technical features described in the specification, the other technical features are known to those skilled in the art. To highlight the innovative features of this invention, the other technical features will not be described in detail here.

Claims

1. A method for preparing a methacrylate lactate monomer, characterized in that, Including raw materials: Lactic acid and glycidyl methacrylate in a molar ratio of (0.9~1.1):1; Including the following steps: Step S1. Mixing: Mix lactic acid, glycidyl methacrylate, polymerization inhibitor and catalyst evenly; Step S2. Reaction: Under inert gas protection, the reaction mixture obtained in step S1 is heated to 60~90℃ and stirred for 4~10 hours; Step S3. Cool to room temperature, then purify to obtain methacrylate lactate monomer.

2. The method for preparing methacrylate lactate monomer according to claim 1, characterized in that, The lactic acid is one or more of L-lactic acid, D-lactic acid, or DL-lactic acid; and / or The polymerization inhibitor is one or more selected from hydroquinone, p-hydroxyanisole, and 2,6-di-tert-butyl-p-cresol; and / or... The amount of polymerization inhibitor added is 0.1% to 1% of the total mass of the reactants, where the total mass of the reactants is the sum of the masses of lactic acid, glycidyl methacrylate, polymerization inhibitor, and catalyst; and / or, The catalyst is one or more of triethylamine, triphenylphosphine, tetrabutylammonium bromide, chromium chloride, and stannous octoate; and / or, The amount of catalyst added is 0.5% to 3% of the total mass of the reactants, where the total mass of the reactants is the sum of the masses of lactic acid, glycidyl methacrylate, polymerization inhibitor, and catalyst.

3. The method for preparing methacrylate lactate monomer according to claim 1, characterized in that, The post-processing purification method in step S3 includes water washing and purification, wherein the purification is performed by vacuum distillation or column chromatography.

4. A methacrylate lactate monomer, characterized in that, The monomer is prepared by the preparation method according to any one of claims 1-3, and has the following structural formula: 。 5. A method for preparing a bio-based acrylic resin, characterized in that, The raw materials include, by mass percentage: a) 5%~50% methacrylate lactate monomer, wherein the methacrylate lactate monomer is the methacrylate lactate monomer prepared by any one of the preparation methods of claims 1-3 or the methacrylate lactate monomer of claim 4; b) 20%~95% (meth)acrylic acid comonomers; It also includes a third monomer: selected from one or more of butyl acrylate monomers, styrene monomers, or acrylonitrile monomers; The total mass of the methacrylate lactate monomer, the (meth)acrylate comonomer, and the third monomer is 100%. include step: Step 1, Preheating: Add part of the solvent and part of the initiator to the reactor and heat to a reflux temperature of 56.5~137℃; Step 2: Preparation of premix: Mix the methacrylate lactate monomer, (meth)acrylate comonomer, remaining solvent and remaining initiator evenly to prepare a premix; Step 3: Slowly add the premixed solution obtained in Step 2 to the reactor in Step 1 over 2-4 hours. After the addition is complete, keep the reactor at a reflux temperature of 56.5-137℃ for 2-6 hours. After the reaction is complete, the mixture is cooled to room temperature and discharged to obtain the bio-based acrylic resin.

6. The method for preparing the bio-based acrylic resin according to claim 5, characterized in that, The (meth)acrylic comonomers include one or more of methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hydroxyethyl (meth)acrylate, and (meth)acrylic acid.

7. The method for preparing the bio-based acrylic resin according to claim 5, characterized in that, The initiator is one of azobisisobutyronitrile, benzoyl peroxide, and di-tert-butyl peroxide; and / or... The initiator is used in an amount of 0.5% to 3% of the total monomer mass; and / or, The solvent is one or more of toluene, xylene, ethyl acetate, butyl acetate, acetone, isopropanol, and butanol.

8. A coating comprising the bio-based acrylic resin prepared by the preparation method according to any one of claims 5-7, characterized in that, The coating meets the following performance requirements: bio-based content ≥7.7%, hardness ≥H.

9. A method for preparing the coating according to claim 8, characterized in that, The bio-based acrylic resin prepared by any one of claims 5-7 is coated onto the substrate, leveled at room temperature, and then cured in an oven at 80°C for 1 hour to form a coating.

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