Polysaccharide acrylic resin and preparation method thereof

Abstract

The invention relates to polysaccharide acrylic resin and a preparation method thereof, and belongs to the technical field of intersection of high value-added utilization of biomass resources and acrylic resin. The polysaccharide acrylic resin is prepared from the following components in parts by weight: 40 to 50 parts of acrylic modified polysaccharide, 10 to 30 parts of acrylic monomer, 20 to 30 parts of polybasic acid, 10 to 15 parts of polyhydric alcohol, 3 to 5 parts of emulsifier, 0.4 to 0.6 part of initiator, 0.1 to 0.3 part of defoaming agent, 1 to 3 parts of catalyst and 60 to 80 parts of deionized water. Coffee grounds are subjected to impurity removal, lignin removal, acid hydrolysis and acrylic acid group modification, so that the coffee grounds are converted into delignification coffee grounds with high cellulose and hemicellulose content, then the delignification coffee grounds are hydrolyzed into polysaccharide with high chemical reaction activity, finally acrylic acid group modified polysaccharide is formed, acrylic acid groups are grafted on molecular chains, and the modified polysaccharide is obtained. Polysaccharide molecules have a large amount of hydroxyl groups which further react with polybasic acid to form a net-shaped cross-linked molecular chain, so that the acrylic resin after film formation has higher strength performance.

Description

Technical Field

[0001] The present invention belongs to the cross - technical field of high - value utilization of biomass resources and acrylic resins, and particularly relates to a polysaccharide acrylic resin and a preparation method thereof. Background Art

[0002] In the field of coating applications, biobased materials, especially vegetable oils, have been widely used to prepare new types of green and environmentally friendly coatings. This is because vegetable oils have characteristics such as non - toxicity, low volatility, biodegradability, and abundant and easily available raw materials. Since the 19th century, a series of studies on vegetable oil - based polymers have been carried out. For example, after the triglycerides in vegetable oils are alcoholyzed with glycerol, monoglycerides are obtained for preparing alkyd resins; drying oils or fatty acids are first maleated and then subjected to a transesterification reaction with epoxy prepolymers to prepare fatty acid - modified epoxy coatings; soybean oil is epoxidized and then combined with acrylate to prepare epoxidized soybean oil acrylate resin; monoglyceride is also a polyol and can react with diisocyanates to prepare polyurethanes. Vegetable oils used for preparing water - based polyurethanes include sunflower oil, castor oil, rapeseed oil, soybean oil, etc.; tung oil forms a biodegradable coating directly after thermal cross - linking polymerization.

[0003] In the field of coating applications, biobased materials, especially vegetable oils, have been widely used to prepare new types of green and environmentally friendly coatings. This is because vegetable oils have characteristics such as non - toxicity, low volatility, biodegradability, and abundant and easily available raw materials. Since the 19th century, a series of studies on vegetable oil - based polymers have been carried out. For example, after the triglycerides in vegetable oils are alcoholyzed with glycerol, monoglycerides are obtained for preparing alkyd resins; drying oils or fatty acids are first maleated and then subjected to a transesterification reaction with epoxy prepolymers to prepare fatty acid - modified epoxy coatings; soybean oil is epoxidized and then combined with acrylate to prepare epoxidized soybean oil acrylate resin; monoglyceride is also a polyol and can react with diisocyanates to prepare polyurethanes. Vegetable oils used for preparing water - based polyurethanes include sunflower oil, castor oil, rapeseed oil, soybean oil, etc.; tung oil forms a biodegradable coating directly after thermal cross - linking polymerization. However, the demand for vegetable oils as human food is also increasing continuously. Therefore, using vegetable oils as raw materials for synthetic resins results in relatively high production costs. Thus, it is urgently needed to explore a method to synthesize the required resins with inexpensive and widely - sourced biomaterials.

[0004] Coffee is one of the world's three major beverages. Between 2000 and 2012, the global coffee production increased by nearly 17%. According to the data of the International Coffee Organization, the global coffee processing volume in 2017 was about 9.6 million tons. In coffee production steps such as roasting and brewing, more than 90% of the initial dry coffee mass is generated in the form of coffee grounds. The waste generated from coffee in coffee-producing countries accounts for more than 50% of the total fruit residues. Therefore, coffee grounds are a kind of agroforestry waste with a large output, and coffee factories need to spend a certain cost to treat coffee grounds. The composition of coffee grounds is relatively complex, mainly including lignin, cellulose, hemicellulose and lipids, as well as a small amount of substances such as proteins, polyphenols and minerals. Among them, the lignin content is about 30wt%, and the total content of cellulose and hemicellulose is about 40 - 50wt%. The resource utilization of coffee grounds can not only reduce the environmental pollution caused by coffee grounds, but also bring certain economic benefits. Summary of the Invention

[0005] Aiming at the above deficiencies, the purpose of the present invention is to provide a polysaccharide acrylic resin and its preparation method. By removing impurities, removing lignin, acid hydrolysis and acrylic group modification of coffee grounds, the coffee grounds are converted into delignified coffee grounds with high cellulose and hemicellulose content, and then hydrolyzed into polysaccharides with high chemical reactivity, and finally acrylic group-modified polysaccharides are formed. As Figure 1 shown, acrylate groups are grafted through reaction with 3-formyl-2-butenoic acid (synthesized by hydrolysis of methyl 3-formyl-2-butenoate (CAS: 96928-85-7)) at the molecular link branches, and react with acrylic monomers to form interlaced molecular chains. And the polysaccharide molecules have a large number of hydroxyl groups to further react with polyacids to form a network-crosslinked molecular chain, so that the formed acrylic resin has high strength performance. At the same time, the acrylic resin prepared by the present invention uses bio-based raw materials and has biodegradability, and will automatically degrade in the environment after being used up later, without causing a burden on the environment.

[0006] The specific technical solutions are as follows:

[0007] A polysaccharide acrylic resin, by weight, the composition of the polysaccharide acrylic resin is: 40 - 50 parts of acrylate-modified polysaccharide, 10 - 30 parts of acrylic monomer, 20 - 30 parts of polyacid, 10 - 15 parts of polyol, 3 - 5 parts of emulsifier, 0.4 - 0.6 parts of initiator, 0.1 - 0.3 parts of defoamer, 1 - 3 parts of catalyst, 60 - 80 parts of deionized water; the preparation of the acrylate-modified micro-nano coffee grounds includes the following steps:

[0008] S1 Impurity removal: Immerse coffee grounds in n - hexane. The mass - to - volume ratio of coffee grounds to n - hexane is 5 - 10 g:1 - 10 mL. React at 20 - 30 °C with a mechanical stirring speed of 200 - 500 revolutions per minute for 3 - 6 hours. Filter to remove the filtrate, obtaining coffee grounds after impurity removal;

[0009] S2 Delignification: Immerse the coffee grounds after impurity removal in a sodium hydroxide solution with a concentration of 5wt% - 12wt%. The mass - to - volume ratio of coffee grounds to sodium hydroxide is 1 - 10 g:1 - 5 mL. React at 80 - 100 °C with a mechanical stirring speed of 500 - 1000 revolutions per minute for 1 - 3 hours. Filter and collect the filter residue; Immerse the filter residue in 3 - 10wt% hydrogen peroxide. The mass - to - volume ratio of the filter residue to hydrogen peroxide is 5 - 10 g:1 - 5 mL. Adjust the pH value of the mixed solution to 10 - 12 and react at 80 - 100 °C for 2 - 5 hours until the filter residue turns white, obtaining delignified coffee grounds;

[0010] S3 Acid hydrolysis: Immerse the delignified coffee grounds in a dilute hydrochloric acid solution with a concentration of 1M - 3M. React at a temperature of 30 - 40 °C and a stirring speed of 200 - 500 revolutions per minute for 3 - 5 hours. Filter to remove the filtrate, wash with deionized water until the filtrate is neutral, and dry to obtain polysaccharides;

[0011] S4 Acrylic - based modified polysaccharides: By mass, sequentially add 30 - 40 parts of polysaccharides, 20 - 30 parts of 3 - formyl - 2 - butenoic acid, and 10 - 20 parts of 1,4 - dioxane to a multi - functional reaction kettle. While stirring at a speed of 500 - 1000 revolutions per minute, heat the reactants to 50 - 60 °C and react for 4 - 6 hours until the reaction ends; Then use vacuum distillation to heat to 30 - 40 °C and a pressure of 55 - 65 mbar to distill, distill out 1,4 - dioxane and unreacted 3 - formyl - 2 - butenoic acid and collect and store them. Filter the distilled solution, collect the filter residue, and air - dry the filter residue at 30 °C to obtain purified acrylic - based modified polysaccharides.

[0012] In some embodiments, the preparation method of the 3 - formyl - 2 - butenoic acid in S4 includes the following steps:

[0013] S5 Add methyl 3 - formyl - 2 - butenoate to a multi - functional reaction kettle, add sodium hydroxide to adjust the pH to 11.6 - 13.8, and react at a stirring speed of 200 - 500 revolutions per minute and a temperature of 30 - 50 °C for 2 - 6 hours;

[0014] S6 Add hydrochloric acid to the solution after the reaction in S4 until the pH of the mixed solution is 1 - 3, then raise the temperature to 76.8 - 85 °C and distill to collect the distillate;

[0015] The obtained fraction was added with anhydrous magnesium sulfate for drying to remove the excess water, and 3-formyl-2-butenoic acid was obtained.

[0016] In some embodiments, the acrylic monomer may be one or a combination of more of methyl acrylate, ethyl acrylate, butyl acrylate, methacrylic acid, methyl methacrylate, isobutyl acrylate, hexyl acrylate, isooctyl acrylate, lauryl acrylate.

[0017] In some embodiments, the polybasic acid may be one or a combination of more of phthalic anhydride, terephthalic acid, acetic anhydride, maleic anhydride.

[0018] In some embodiments, the polyhydric alcohol may be one or a combination of more of glycerol, pentaerythritol, trimethylolethane, trimethylolpropane.

[0019] In some embodiments, the emulsifier may be one or a combination of more of sodium stearate, sodium stearoyl glutamate, and cetyl potassium phosphate.

[0020] In some embodiments, the initiator may be one or a combination of more of benzoyl peroxide, tert-butyl hydroperoxide, and tert-amyl peroxyacetate.

[0021] In some embodiments, the defoamer may be one or a combination of more of sucrose fatty acid ester, polyglycerol fatty acid ester.

[0022] In some embodiments, the catalyst may be one or a combination of more of antimony trioxide, Sn(Oct) 2 and the like.

[0023] The present invention also provides a preparation method of the above polysaccharide acrylic resin, and the preparation method includes the following steps:

[0024] S5 In a multi-functional reaction kettle, according to the formula weight, the acrylic monomer, deionized water, emulsifier, and defoamer are sequentially added, and then while introducing nitrogen, stirring is carried out at a speed of 500-1000 revolutions per minute for 10-30 minutes to obtain an emulsion, and then acrylic group-modified polysaccharide is added, and stirring is continued for 10-30 minutes to obtain a uniformly mixed solution, and nitrogen is continuously introduced for 5-10 minutes;

[0025] S6 Stop introducing nitrogen, heat up to 100-110 °C, then add the initiator in the formula amount, continue to stir evenly to initiate the polymerization reaction, keep the temperature for 2 hours, and separate the generated water vapor with a water separator during this period;

[0026] After the reaction in S7 is completed, a polybasic acid, a polyhydric alcohol and a catalyst are added in sequence, and the temperature is continuously raised to 140-160 °C and kept warm for 0.5-1 hour to completely dissolve the materials to form a homogeneous solution. Then the temperature is continuously raised to 180-200 °C to initiate the esterification reaction, and the reaction is carried out for 4-6 hours. During this period, the generated water vapor is separated by a water separator;

[0027] After the reaction in S8 is completed, a sample is taken every 30 minutes for acid value testing. When the acid value is 50-60 mg KOH / g, the reaction is stopped; the temperature is lowered to 50 °C and kept warm, and dispersed for 30-60 minutes at a stirring speed of 8000-10000 revolutions per minute. Deionized water in the formula amount is added to make the viscosity of the mixed solution 9000-12000 cps / 25 °C. Then, it is continuously stirred for 30-60 minutes at a stirring speed of 800-1000 revolutions per minute to obtain the polysaccharide acrylic resin.

[0028] The present invention has the following advantages:

[0029] (1) Using coffee grounds, a by-product of the coffee industry, as a production raw material, the cost is relatively low. At the same time, it can reduce the environmental pollution caused by coffee grounds, realize the high-value utilization of waste, and provide a new way for the utilization of coffee grounds;

[0030] (2) The formula does not involve the use of organic solvents, and no gas harmful to human health will be generated during the subsequent use of the acrylic resin coating, which conforms to the green environmental protection production concept;

[0031] (3) In the present invention, through impurity removal, delignification, acid hydrolysis and acrylic group modification of coffee grounds, the coffee grounds are converted into delignified coffee grounds with high cellulose and hemicellulose contents, and then hydrolyzed into polysaccharides with high chemical reactivity. Finally, acrylic group-modified polysaccharides are formed, acrylic groups are grafted on the molecular chain, and react with acrylic monomers to form interlaced molecular chains. Moreover, the polysaccharide molecules have a large number of hydroxyl groups that further react with polybasic acids to form a network-crosslinked molecular chain, so that the formed acrylic resin has high strength performance;

[0032] (4) The acrylic resin prepared by the present invention uses a bio-based raw material and has biodegradability. It will automatically degrade in the environment after being used up later and will not cause a burden to the environment. Description of the Drawings

[0033] Figure 1 Schematic molecular diagram of the chemical reaction formula for preparing polysaccharide-based acrylic resin from delignified coffee grounds;

[0034] Figure 2 From left to right are the scanning electron microscope images of coffee grounds before treatment and coffee grounds after treatment in Examples 1-3;

[0035] Figure 3 Optical photographs of the polysaccharide acrylate resins prepared in Examples 12 to 14;

[0036] Figure 4 Biodegradation test results of the polysaccharide acrylate resins prepared in Examples 12 to 14. Detailed implementation manners

[0037] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings, technical process steps, specific implementation conditions and materials in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0038] Example 1

[0039] The coffee grounds were soaked in n-hexane, and the mass-volume ratio of coffee grounds to n-hexane was 5 g: 1 mL. The reaction was carried out at 20 °C with a mechanical stirring speed of 500 revolutions per minute for 3 hours. The filtrate was removed by filtration to obtain coffee grounds after impurity removal. The coffee grounds after impurity removal were soaked in a 5 wt% sodium hydroxide solution, and the mass-volume ratio of coffee grounds to sodium hydroxide was 1 g: 2 mL. The reaction was carried out at 100 °C with a mechanical stirring speed of 500 revolutions per minute for 3 hours, and then filtered, and the filtrate and the filter residue were collected separately. The filter residue was soaked in 3 wt% hydrogen peroxide, and the mass-volume ratio of the filter residue to hydrogen peroxide was 5 g: 5 mL. The pH value of the mixed solution was adjusted to 12, and the reaction was carried out at 100 °C for 2 hours until the filter residue turned white.

[0040] The micro-morphologies of the original coffee grounds and the treated coffee grounds were characterized by scanning electron microscopy as Figure 2 shown. The surface of the coffee grounds before treatment had no pores and was filled with substances such as lignin, lipids, and proteins, while the surface of the treated coffee grounds was honeycombed with a rich pore structure, indicating that substances such as lignin, lipids, and proteins had been removed.

[0041] The contents of lignin (acid-insoluble lignin), cellulose, and hemicellulose in the coffee grounds before and after treatment were determined according to GB / T 2677.8-947, GB / T 2677.10-19957, and the nitric acid-ethanol method, respectively. The measurement results are shown in Table 1, and the results indicate that a large amount of lignin was removed after treatment, while a large amount of cellulose and hemicellulose were retained.

[0042] Table 1 Contents of lignin, cellulose, and hemicellulose in coffee grounds before and after treatment

[0043] Sample Name Lignin (%) Hemicellulose (%) Cellulose (%) Coffee Grounds before Treatment 30.3±1.5 51.5±0.5 18.2±0.8 Coffee Grounds after Treatment 4.8±0.5 53.6±0.7 41.8±0.5

[0044] Example 2

[0045] The coffee grounds are soaked in n - hexane. The mass - volume ratio of coffee grounds to n - hexane is 7 g:8 mL. The reaction is carried out at 30 °C with a mechanical stirring speed of 200 revolutions per minute for 6 hours. The filtrate is removed by filtration to obtain the coffee grounds after impurity removal. The coffee grounds after impurity removal are soaked in a sodium hydroxide solution with a concentration of 12 wt%. The mass - volume ratio of coffee grounds to sodium hydroxide is 10 g:5 mL. The reaction is carried out at 90 °C with a mechanical stirring speed of 1000 revolutions per minute for 3 hours. After filtration, the filtrate and the filter residue are collected separately. The filter residue is soaked in 10 wt% hydrogen peroxide. The mass - volume ratio of filter residue to hydrogen peroxide is 5 g:5 mL. The pH value of the mixed solution is adjusted to 11, and the reaction is carried out at 90 °C for 5 hours until the filter residue turns white.

[0046] Table 2 Contents of lignin, cellulose and hemicellulose in coffee grounds before and after treatment

[0047] Sample Name Lignin (%) Hemicellulose (%) Cellulose (%) Coffee Grounds before Treatment 30.3±1.5 51.5±0.5 18.2±0.8 Coffee Grounds after Treatment 3.5±1.09 52.7±1.27 44.3±0.9

[0048] The micro - morphology of the treated coffee grounds is characterized by scanning electron microscopy as Figure 2 shown. The surface of the treated coffee grounds is honey - comb - shaped and has a rich pore structure, indicating that substances such as lignin, lipids, and proteins have been removed.

[0049] The contents of lignin (acid - insoluble lignin), cellulose and hemicellulose in coffee grounds before and after treatment are determined according to GB / T2677.8 - 947, GB / T 2677.10 - 19957 and the nitric acid - ethanol method respectively. The measurement results are shown in Table 2. The results show that a large amount of lignin has been removed after treatment, and a large amount of cellulose and hemicellulose have been retained.

[0050] Example 3

[0051] The coffee grounds are soaked in n - hexane. The mass - volume ratio of coffee grounds to n - hexane is 10 g:10 mL. The reaction is carried out at 30 °C with a mechanical stirring speed of 200 revolutions per minute for 4 hours. The filtrate is removed by filtration to obtain the coffee grounds after impurity removal. The coffee grounds after impurity removal are soaked in a sodium hydroxide solution with a concentration of 8 wt%. The mass - volume ratio of coffee grounds to sodium hydroxide is 5 g:5 mL. The reaction is carried out at 80 °C with a mechanical stirring speed of 500 revolutions per minute for 3 hours. After filtration, the filtrate and the filter residue are collected separately. The filter residue is soaked in 7 wt% hydrogen peroxide. The mass - volume ratio of filter residue to hydrogen peroxide is 10 g:5 mL. The pH value of the mixed solution is adjusted to 10, and the reaction is carried out at 80 °C for 4 hours until the filter residue turns white;

[0052] The micro - morphologies of the original coffee grounds and the treated coffee grounds are characterized by scanning electron microscopy as Figure 2As shown, the surface of the coffee grounds before treatment has no pores and is filled with substances such as lignin, lipids, and proteins. After treatment, the surface of the coffee grounds is honeycombed with a rich pore structure, indicating that substances such as lignin, lipids, and proteins have been removed.

[0053] The contents of lignin (acid-insoluble lignin), cellulose, and hemicellulose in the coffee grounds before and after treatment were determined according to GB / T 2677.8 - 1994, GB / T 2677.10 - 1995, and the nitric acid-ethanol method, respectively. The measurement results are shown in Table 3. The results indicate that a large amount of lignin has been removed after treatment, while a large amount of cellulose and hemicellulose has been retained.

[0054] Table 3 Contents of lignin, cellulose, and hemicellulose in coffee grounds before and after treatment

[0055] Sample Name Lignin (%) Hemicellulose (%) Cellulose (%) Coffee Grounds before Treatment 30.3±1.5 51.5±0.5 18.2±0.8 Coffee Grounds after Treatment 5.3±0.77 49.8±0.56 44.8±1.2

[0056] Example 4

[0057] The delignified coffee grounds prepared in Example 1 were soaked in a 1 M dilute hydrochloric acid solution at a temperature of 40 °C and a stirring speed of 500 revolutions per minute for 5 hours. The filtrate was removed by filtration, and the residue was washed with deionized water until the filtrate was neutral, and then dried to obtain polysaccharides.

[0058] Example 5

[0059] The delignified coffee grounds prepared in Example 2 were soaked in a 2 M dilute hydrochloric acid solution at a temperature of 35 °C and a stirring speed of 300 revolutions per minute for 4 hours. The filtrate was removed by filtration, and the residue was washed with deionized water until the filtrate was neutral, and then dried to obtain polysaccharides.

[0060] Example 6

[0061] The delignified coffee grounds prepared in Example 3 were soaked in a 3 M dilute hydrochloric acid solution at a temperature of 30 °C and a stirring speed of 200 revolutions per minute for 3 hours. The filtrate was removed by filtration, and the residue was washed with deionized water until the filtrate was neutral, and then dried to obtain polysaccharides.

[0062] Example 7

[0063] The degree of polymerization of the polysaccharides prepared in Examples 4 - 6 was tested by mass spectrometry. The polysaccharides prepared in Examples 4 - 6 were respectively formed into uniform solutions, then the liquid was converted into charged aerosol particles, and then analyzed by a mass spectrometer to obtain the degree of polymerization of the polysaccharides. The results show that the degrees of polymerization of the polysaccharides prepared in Examples 4 - 6 are 78 - 100, 59 - 82, and 36 - 57, respectively.

[0064] Example 8

[0065] Methyl 3-formyl-2-butenoate was added to a multi-functional reaction kettle, and sodium hydroxide was added to adjust the pH to 12.7. Under a stirring speed of 300 revolutions per minute and a temperature of 40 °C, the reaction was carried out for 4 hours. The reaction solution was added with hydrochloric acid until the pH of the mixed solution was 2, and then the temperature was raised to 79.4 °C for distillation to collect the distillate; the obtained distillate was added with anhydrous magnesium sulfate for drying to remove excess water, and 3-formyl-2-butenoic acid was obtained.

[0066] Example 9

[0067] By mass, 30 parts of the polysaccharide prepared in Example 4, 20 parts of 3-formylbutenoic acid, and 10 parts of 1,4-dioxane were successively added to a multi-functional reaction kettle. Under a stirring speed of 500 revolutions per minute, the reactants were heated to 50 °C and the reaction was carried out for 6 hours until the reaction ended; then it was heated to 30 °C under reduced pressure distillation at a pressure of 55 mbar for distillation to distill out 1,4-dioxane and unreacted 3-formylbutenoic acid and collect and store them. The distilled solution was filtered, the filter residue was collected, and the filter residue was air-dried at 30 °C to obtain purified acrylic acid-based modified polysaccharide.

[0068] Example 10

[0069] By mass, 35 parts of the polysaccharide prepared in Example 5, 25 parts of 4-formylpentenoic acid, and 15 parts of 1,4-dioxane were successively added to a multi-functional reaction kettle. Under a stirring speed of 800 revolutions per minute, the reactants were heated to 55 °C and the reaction was carried out for 5 hours until the reaction ended; then it was heated to 35 °C under reduced pressure distillation at a pressure of 60 mbar for distillation to distill out 1,4-dioxane and unreacted 4-formylpentenoic acid and collect and store them. The distilled solution was filtered, the filter residue was collected, and the filter residue was air-dried at 30 °C to obtain purified acrylic acid-based modified polysaccharide.

[0070] Example 11

[0071] By mass, 40 parts of the polysaccharide prepared in Example 6, 30 parts of 5-formylhexenoic acid, and 20 parts of 1,4-dioxane were successively added to a multi-functional reaction kettle. Under a stirring speed of 1000 revolutions per minute, the reactants were heated to 60 °C and the reaction was carried out for 4 hours until the reaction ended; then it was heated to 40 °C under reduced pressure distillation at a pressure of 65 mbar for distillation to distill out 1,4-dioxane and unreacted 5-formylhexenoic acid and collect and store them. The distilled solution was filtered, the filter residue was collected, and the filter residue was air-dried at 30 °C to obtain purified acrylic acid-based modified polysaccharide.

[0072] Example 12

[0073] The total carboxyl content in the prepared acrylic acid-based modified polysaccharide was determined by alkaline hydrolysis and back titration to determine the acrylic acid grafting rate of the polysaccharide. 0.5 g of the sample was added to 40 ml (70%) ethanol solution, and the resulting suspension was continuously stirred for 30 minutes. Then 20 ml (0.5 M) NaOH solution was added to the suspension and hydrolyzed at 60 °C for 48 hours. Using phenolphthalein as an indicator, the unconsumed NaOH was titrated after hydrolysis with HCl (0.5 M) solution.

[0074]

[0075] Where V B is the volume of NaOH, V s is the volume of HCl consumed in the titration, C HCl is the concentration of HCl, m is the dry weight of the acrylic acid-based modified polysaccharide. The results show that the total carboxyl contents of the polysaccharides prepared in Examples 4, 5 and 6 are 0.13, 0.16 and 0.17 mmol g -1 , respectively, and the total carboxyl contents of the acrylic acid-based modified polysaccharides prepared in Examples 8, 9 and 10 are 0.89, 1.12 and 0.92 mmol g -1 .

[0076] The free carboxyl contents of the polysaccharides prepared in Examples 4, 5 and 6 and the acrylic acid modified polysaccharides prepared in Examples 7, 8 and 9 were determined by conductometric titration. 50 mg of the sample was selected, then 10 ml (0.01 M) HCl was added, and ultrasonic treatment was carried out for 4 hours. Finally, the suspension was titrated with NaOH (0.01 M).

[0077]

[0078] Where, C NaOH is the concentration of NaOH (0.01 M), V NaOH is the volume of NaOH required to titrate all HCl, m is the dry weight of the sample. The results show that the free carboxyl contents of the polysaccharides prepared in Examples 4, 5 and 6 are 0.05, 0.08 and 0.12 mmol g -1 , respectively, and the free carboxyl contents of the acrylic acid modified polysaccharides prepared in Examples 8, 9 and 10 are 0.54, 0.97 and 0.68 mmol g -1 , that is, the grafting rates of the acrylic acid groups of the acrylic acid modified polysaccharides prepared in Examples 7, 8 and 9 are about 0.54, 0.97 and 0.68 mmol g -1 .

[0079] Example 13

[0080] In a multi-functional reaction kettle, isobutyl acrylate, deionized water, sodium stearate and sucrose fatty acid ester were sequentially added according to the formula weight. Then, while introducing nitrogen, stirring was carried out at a speed of 500 revolutions per minute for 30 minutes to obtain an emulsion. Then, acrylate-based modified polysaccharide was added, and stirring was continued for 30 minutes to obtain a homogeneous mixture. Nitrogen was continuously introduced for 10 minutes. The introduction of nitrogen was stopped, and the temperature was raised to 100 °C. Then, the formulated amount of tert-amyl peroxyacetate was added, and stirring was continued until evenly mixed to initiate the polymerization reaction. The temperature was maintained for 2 hours, and the generated water vapor was separated by a water separator during this period. After the reaction was completed, maleic anhydride, trimethylolpropane and Sn(Oct) were added in sequence 2 , and the temperature was further raised to 140 °C and maintained for 1 hour to completely dissolve the materials and form a homogeneous solution. Then, the temperature was further raised to 180 °C to initiate the esterification reaction, and the reaction was carried out for 6 hours. The generated water vapor was separated by a water separator during this period. After the reaction was completed, samples were taken every 30 minutes for acid value testing. When the acid value was 50 - 60 mg KOH / g, the reaction was stopped; the temperature was lowered to 50 °C and maintained. Dispersion was carried out at a stirring speed of 8000 revolutions per minute for 60 minutes, and the formulated amount of deionized water was added to make the viscosity of the mixed solution 9000 cps / 25 °C. Then, stirring was continued at a stirring speed of 800 revolutions per minute for 60 minutes to obtain the polysaccharide acrylate resin.

[0081] Table 4 Raw material ratio for synthesizing polysaccharide acrylate resin in Example 13

[0082]

[0083]

[0084] The acrylate-based modified polysaccharide in Table 4 was prepared by the method described in Example 9.

[0085] According to GB / T 6739-1996 "Pencil Test Method for Film Hardness", the strength of the polysaccharide acrylate resin film (cured at 50 °C for 3 hours) prepared was tested by the manual method, and the test results showed that the film strength > B.

[0086] According to GB / T 23985-2009 "Determination of Volatile Organic Compounds (VOC) Content in Paints and Varnishes - Difference Method", the VOC of the polysaccharide acrylate resin film prepared was tested, and the result was VOC ≤ 42.19.

[0087] According to GB / T 1727-1992, the water resistance of the polysaccharide acrylate resin film prepared was tested. After soaking for 48 hours, the water absorption rate was 12.59%.

[0088] The tensile strength of the polysaccharide acrylate resin film (cured at 50 °C for 3 hours) after film formation was tested with a universal tensile testing machine, and the film strength was 184.57 kPa.

[0089] Example 14

[0090] In a multi-functional reaction kettle, according to the formula weight, isooctyl acrylate, deionized water, sodium stearoyl glutamate and polyglycerol fatty acid ester were added in sequence. Then, while introducing nitrogen, stirring was carried out at a speed of 800 revolutions per minute for 20 minutes to obtain an emulsion. Then, acrylate-modified polysaccharide was added, and stirring was continued for 20 minutes to obtain a homogeneous mixture. Nitrogen was continuously introduced for 8 minutes; the introduction of nitrogen was stopped, and the temperature was raised to 105 °C. Then, the formula amount of tert-butyl hydroperoxide was added, and stirring was continued until homogeneous to initiate the polymerization reaction. The temperature was maintained for 2 hours, and the generated water vapor was separated by a water separator during this period; after the reaction was completed, acetic anhydride, trimethylolethane and antimony trioxide were added in sequence, and the temperature was further raised to 150 °C and maintained for 0.8 hours to completely dissolve the materials and form a homogeneous solution. Then, the temperature was further raised to 190 °C to initiate the esterification reaction, and the reaction was carried out for 5 hours, and the generated water vapor was separated by a water separator during this period; after the reaction was completed, samples were taken every 30 minutes for acid value testing. When the acid value was 50 - 60 mg KOH / g, the reaction was stopped; the temperature was lowered to 50 °C and maintained, and dispersion was carried out at a stirring speed of 9000 revolutions per minute for 45 minutes. The formula amount of deionized water was added to make the viscosity of the mixed solution 10000 cps / 25 °C. Then, stirring was continued at a stirring speed of 900 revolutions per minute for 45 minutes to obtain polysaccharide acrylate resin.

[0091] Table 5 Raw material ratio for synthesizing polysaccharide acrylate resin in Example 14

[0092]

[0093]

[0094] The acrylate-modified polysaccharide in Table 5 was prepared by the method described in Example 10.

[0095] According to GB / T 6739-1996 "Pencil Test Method for Film Hardness", the strength of the polysaccharide acrylate resin film after film formation (cured at 50 °C for 3 hours) was tested by the manual method. The test results showed that the film strength > B.

[0096] According to GB / T 23985-2009 "Determination of Volatile Organic Compounds (VOC) Content in Paints and Varnishes - Difference Method", the VOC of the polysaccharide acrylate resin film prepared was tested, and the result was VOC ≤ 42.69.

[0097] According to GB / T 1727-1992, the water resistance of the polysaccharide acrylate resin film prepared was tested. After soaking for 48 hours, the water absorption rate was 11.54%.

[0098] The tensile strength of the polysaccharide acrylic resin film after film formation (cured at 50 °C for 3 hours) was tested using a universal tensile testing machine, and the film strength was 211.95 kPa.

[0099] Example 15

[0100] In a multi-functional reaction kettle, according to the formula weight, methyl methacrylate, deionized water, potassium cetyl phosphate, and polyglycerol fatty acid ester were added in sequence. Then, while introducing nitrogen, stirring was carried out at a speed of 1000 revolutions per minute for 10 minutes to obtain an emulsion. Then, acrylic group-modified polysaccharide was added, and stirring was continued for 10 minutes to obtain a homogeneous mixture. Nitrogen was continuously introduced for 5 minutes; the introduction of nitrogen was stopped, and the temperature was raised to 110 °C. Then, the formula amount of benzoyl peroxide was added, and stirring was continued evenly to initiate the polymerization reaction. The temperature was maintained for 2 hours, and the generated water vapor was separated by a water separator during this period; after the reaction was completed, terephthalic acid, glycerol, and Sn(Oct) 2 were added in sequence. The temperature was further raised to 160 °C and maintained for 0.5 hour to completely dissolve the materials and form a homogeneous solution. Then, the temperature was further raised to 200 °C to initiate the esterification reaction, and the reaction was carried out for 4 hours. The generated water vapor was separated by a water separator during this period; after the reaction was completed, samples were taken every 30 minutes for acid value testing. When the acid value was 50 - 60 mg KOH / g, the reaction was stopped; the temperature was lowered to 50 °C and maintained. Under a stirring speed of 10000 revolutions per minute, it was dispersed for 30 minutes, and the formula amount of deionized water was added to make the viscosity of the mixed solution 9000 - 12000 cps / 25 °C. Then, under a stirring speed of 1000 revolutions per minute, stirring was continued for 30 minutes to obtain the polysaccharide acrylic resin.

[0101] In some embodiments, the catalyst can be antimony trioxide, Sn(Oct) 2 or a combination of one or more of them.

[0102] Table 6 Raw material ratio for synthesizing polysaccharide acrylic resin in Example 15

[0103] Acrylic Modified Polysaccharide 40 - 50 parts Methyl Methacrylate 10 - 30 parts Terephthalic Acid 20 - 30 parts Glycerol 10 - 15 parts Potassium Cetyl Phosphate 3 - 5 parts Benzoyl Peroxide 0.4 - 0.6 parts Polyglycerol Fatty Acid Ester 0.1 - 0.3 parts <![CDATA[Sn(Oct) 2 > 1 - 3 parts Deionized Water 60 - 80 parts

[0104] In Table 6, the acrylic group-modified polysaccharide was prepared by the method described in Example 10.

[0105] According to GB / T 6739-1996 "Pencil Test Method for Film Hardness", the strength of the prepared polysaccharide acrylic resin film after film formation (cured at 50 °C for 3 hours) was tested using the manual method, and the test results showed that the film strength > B.

[0106] According to GB / T 23985-2009 "Determination of Volatile Organic Compound (VOC) Content in Paints and Varnishes - Difference Method", the VOC of the prepared polysaccharide acrylic resin film was tested, and the result was VOC ≤ 29.4.

[0107] The water resistance of the prepared polysaccharide acrylate resin film was tested according to GB / T 1727-1992. After soaking for 48 hours, the water absorption rate was 9.69%.

[0108] The tensile strength of the formed polysaccharide acrylate resin film (cured at 50 °C for 3 hours) was tested with a universal tensile testing machine, and the film strength was 203.41 kPa.

[0109] Example 16

[0110] The polysaccharide-based acrylate resins prepared in Examples 13-15 were added to different molds and cured at 50 °C for 3 hours to form different shapes, such as Figure 3 shown. The results show that the polysaccharide-based acrylate resin prepared by the present invention has good plasticity, transparency and flexibility.

[0111] Example 17

[0112] The polysaccharide-based acrylate resins prepared in Examples 13-15 were cured at 50 °C for 3 hours to form films for biodegradation experiments. They were placed on the soil surface and in the natural environment, and their changes over time were observed, as Figure 4 shown. Examples 13-15 will decompose after 24 weeks, proving that the polysaccharide-based acrylate resin prepared by the present invention has good biodegradability.

[0113] All technicians should note that although the present invention has been described according to the above specific embodiments, the inventive concept of the present invention is not limited to this invention, and any modification using the inventive concept of the present invention will be included in the scope of protection of the patent right of this patent.

Claims

1. A polysaccharide acrylic resin, characterized in that: The polysaccharide acrylic resin is composed of 40-50 parts of acrylic acid-modified polysaccharide, 10-30 parts of acrylic acid monomer, 20-30 parts of polyacid, 10-15 parts of polyol, 3-5 parts of emulsifier, 0.4-0.6 parts of initiator, 0.1-0.3 parts of defoamer, 1-3 parts of catalyst and 60-80 parts of deionized water in parts by weight. The preparation of the acrylic acid-modified micro-nano coffee grounds includes the following steps: S1 impurity removal: soaking coffee grounds in n-hexane, with a mass volume ratio of coffee grounds to n-hexane of 5-10 g:1-10 mL, reacting at 20-30° C. and a mechanical stirring speed of 200-500 rpm for 3-6 hours, filtering and removing the filtrate to obtain the impurity-removed coffee grounds; S2 Delignification: Soak the coffee grounds after impurity removal in a sodium hydroxide solution with a concentration of 5wt% to 12wt%, with a mass volume ratio of coffee grounds to sodium hydroxide of 1 to 10g:1 to 5mL, react at 80 to 100°C and a mechanical stirring speed of 500 to 1000 rpm for 1 to 3 hours, filter, and collect the filter residue; soak the filter residue in 3 to 10wt% hydrogen peroxide, with a mass volume ratio of filter residue to hydrogen peroxide of 5 to 10g:1 to 5mL, adjust the pH value of the mixed solution to 10 to 12, and react at 80 to 100°C for 2 to 5 hours until the filter residue turns white to obtain delignified coffee grounds; S3 acid hydrolysis: soak the delignified coffee grounds in a dilute hydrochloric acid solution with a concentration of 1M to 3M, react for 3 to 5 hours at a temperature of 30 to 40°C and a stirring speed of 200 to 500 rpm, filter out the filtrate, wash with deionized water until the filtrate is neutral, and dry to obtain polysaccharides; S4 acrylic acid-modified polysaccharide: Into a multifunctional reactor, add 30-40 parts of polysaccharide, 20-30 parts of 3-formyl-2-butenoic acid, and 10-20 parts of 1,4-dioxane in order by mass, heat the reactants to 50-60°C at a stirring speed of 500-1000 rpm, and react for 4-6 hours until the reaction is completed; then use reduced pressure distillation to heat to 30-40°C and a pressure of 55-65 mbar for distillation, evaporate 1,4-dioxane and unreacted 3-formyl-2-butenoic acid and collect and store them, filter the distilled solution, collect the filter residue, and air-dry the filter residue at 30°C to obtain purified acrylic acid-modified polysaccharide.

2. A polysaccharide acrylic resin as claimed in claim 1, characterized in that: The preparation method of 3-aldehyde-2-butenoic acid described in S4 comprises the following steps: S5: adding 3-formyl-2-butenoic acid methyl ester into a multifunctional reaction kettle, adding sodium hydroxide to adjust the pH to 11.6-13.8, and reacting for 2-6 hours at a stirring speed of 200-500 rpm and a temperature of 30-50° C.; S6: adding hydrochloric acid to the solution after the reaction in S4 until the pH of the mixed solution is 1 to 3, then heating to 76.8 to 85° C., distilling, and collecting fractions; S7: adding anhydrous magnesium sulfate to the obtained fraction for drying, removing excess water, and obtaining 3-formyl-2-butenoic acid.

3. A polysaccharide acrylic resin as claimed in claim 1, characterized in that: The acrylic monomer may be a combination of one or more of methyl acrylate, ethyl acrylate, butyl acrylate, methacrylic acid, methyl methacrylate, isobutyl acrylate, hexyl acrylate, isooctyl acrylate, and lauryl acrylate.

4. A polysaccharide acrylic resin as claimed in claim 1, characterized in that: The polyacid may be one or more combinations of phthalic anhydride, terephthalic acid, acetic anhydride and maleic anhydride.

5. A polysaccharide acrylic resin as claimed in claim 1, characterized in that: The polyol may be a combination of one or more of glycerol, pentaerythritol, trimethylolethane, and trimethylolpropane.

6. A polysaccharide acrylic resin as claimed in claim 1, characterized in that: The emulsifier may be a combination of one or more of sodium stearate, sodium stearyl glutamate and potassium cetyl phosphate.

7. A polysaccharide acrylic resin as claimed in claim 1, characterized in that: The initiator can be a combination of one or more of benzoyl peroxide, tert-butyl hydroperoxide, and tert-amyl peroxyacetate.

8. A polysaccharide acrylic resin as claimed in claim 1, characterized in that: The defoaming agent can be a combination of one or more of sucrose fatty acid ester and polyglycerol fatty acid ester.

9. A polysaccharide acrylic resin as claimed in claim 1, characterized in that: The catalyst may be a combination of antimony trioxide, Sn(Oct)2 or one or more thereof.

10. The method for preparing a polysaccharide acrylic resin according to any one of claims 1 to 9, characterized in that: The preparation method comprises the following steps: S8: In a multifunctional reactor, acrylic acid monomer, deionized water, emulsifier and defoamer are added in sequence according to the formula weight, and then stirred at a speed of 500 to 1000 rpm for 10 to 30 minutes while introducing nitrogen to obtain an emulsion, and then acrylic acid-modified polysaccharide is added, and stirring is continued for 10 to 30 minutes to obtain a uniform mixed solution, and nitrogen is continued to be introduced for 5 to 10 minutes; S9: Stop introducing nitrogen, heat to 100-110°C, then add the formulated amount of initiator, continue stirring to initiate polymerization, and keep warm for 2 hours, during which time the generated water vapor is separated by a water separator; S10 After the reaction is completed, add polyacid, polyol and catalyst in sequence, continue to heat to 140-160°C, keep warm for 0.5-1 hour, so that the materials are completely dissolved to form a uniform solution, and then continue to heat to 180-200°C to initiate esterification reaction, react for 4-6 hours, during which the generated water vapor is separated by a water separator; S11 After the reaction is completed, samples are taken every 30 minutes for acid value testing. When the acid value is 50-60 mg KOH / g, the reaction is stopped; the temperature is lowered to 50°C and kept warm, and dispersed for 30-60 minutes at a stirring speed of 8000-10000 rpm, and deionized water is added in a formula amount so that the viscosity of the mixed solution is 9000-12000 cps / 25°C, and then the stirring is continued for 30-60 minutes at a stirring speed of 800-1000 rpm to obtain a polysaccharide acrylic resin.

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