Preparation method of water-based environment-friendly emulsion for grainy paper coating

Abstract

The invention relates to the field of emulsions for grainy paper coatings, and discloses a preparation method of a water-based environment-friendly emulsion for a grainy paper coating. The preparation method comprises the following steps: S1, preparing an acrylic carbamate modified monomer from hydroxyethyl acrylate, 2, 4-toluene diisocyanate and diethanol amine; and S2, preparing to obtain the emulsion. S3, obtaining the initiator. S4, deionized water, lauryl sodium sulfate, the emulsion and an initiator are subjected to a polymerization reaction, and an emulsion A is obtained. S5, transferring the emulsion A into a degassing kettle, adding tert-butyl hydroperoxide and vitamin C, and performing oxidation-reduction reaction to obtain emulsion B; and S6, carrying out steam degassing on the emulsion B to obtain the water-based environment-friendly emulsion. The water-based environment-friendly emulsion which is good in stability, glossiness, adhesion fastness, water resistance and weather resistance and low in volatile organic compound content can be prepared, and the preparation method is simple, efficient and environmentally friendly and has wide application prospects and market value.

Description

Technical Field

[0001] The present invention relates to the field of emulsions for wood grain paper coatings, in particular to a preparation method of an environmentally friendly aqueous emulsion for wood grain paper coatings, and also relates to the environmentally friendly aqueous emulsion prepared by the preparation method and the application of the environmentally friendly aqueous emulsion on wood grain paper coatings. Background Art

[0002] After printing artificial wood grain patterns on decorative base paper and then impregnating with resin glue and drying, the resulting film paper is wood grain paper. Wood grain paper belongs to decorative facing paper. Under high temperature and high pressure conditions, the wood grain paper is pressed on the surface of artificial boards to decorate and protect the artificial boards. Furniture, wooden floors, etc. decorated with wood grain paper have water resistance, abrasion resistance, heat resistance, pollution resistance and certain light aging resistance. Using wood grain paper to veneer artificial boards not only improves the utilization rate of wood but also compensates for the natural defects of wood.

[0003] With the continuous improvement of people's awareness of environmental protection, water-based coatings have been widely used in wood grain paper coatings due to their environmental protection and low VOC emissions, and water-based emulsion coatings have high cost performance. However, currently, water-based emulsion coatings on the market generally have problems such as poor adhesion, poor water resistance, and low gloss, and it is difficult to meet the high-quality requirements of wood grain paper coatings. Therefore, developing an environmentally friendly aqueous emulsion with excellent performance is of great significance for improving the decorative effect and service life of wood grain paper coatings. Summary of the Invention

[0004] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a preparation method of an environmentally friendly aqueous emulsion for wood grain paper coatings to obtain an environmentally friendly aqueous emulsion with good stability, gloss, adhesion fastness, water resistance and weather resistance, and low volatile organic compound content.

[0005] A preparation method of an environmentally friendly aqueous emulsion for wood grain paper coatings, which comprises the following steps: S1 Mix and prepare an acrylic carbamate modified monomer by mixing hydroxyethyl acrylate, 2,4-toluene diisocyanate and diethanolamine in a ratio of 0.5 - 1.5:0.5 - 1:1 - 1.5; S2 Take deionized water, sodium dodecyl sulfate, isooctyl acrylate, methyl methacrylate, hydroxyethyl acrylate and the acrylic carbamate modified monomer to prepare an emulsion, and set aside; S3 Take ammonium persulfate and dilute it with deionized water to obtain an initiator, and set aside; S4 Take the remaining deionized water, the remaining sodium dodecyl sulfate, the emulsion and the initiator and add them to a reaction kettle for polymerization reaction to obtain emulsion A; S5 Transfer the emulsion A to a degassing kettle, add tert-butyl hydroperoxide and vitamin C, and carry out a redox reaction to obtain emulsion B; S6 Perform steam degassing treatment on emulsion B, and then cool down and filter to obtain a water-based environmental protection emulsion.

[0006] As a further improvement of the above solution, the preparation method of the acrylic carbamate modified monomer is specifically operated as follows: S11 Dehydrate hydroxyethyl acrylate; S12 Heat 2,4-toluene diisocyanate to 65-70 °C in a container, and under stirring conditions, drop the dehydrated hydroxyethyl acrylate into 2,4-toluene diisocyanate. After dropping, keep the temperature for 3.5 h to obtain a mixed solution; S13 Cool down to 35-40 °C, and under stirring conditions, drop the mixed solution into diethanolamine with a mass fraction of 30% diluted with acetone. After dropping, keep the temperature for 2.5 h; S14 Remove acetone under reduced pressure to obtain the acrylic carbamate modified monomer; In the present invention, the acrylic carbamate modified monomer is used to participate in the copolymerization reaction with the acrylate emulsion, overcoming the problem of formaldehyde release when using hydroxymethyl acrylamide to crosslink with the acrylate emulsion, making the prepared emulsion free of formaldehyde release and more environmentally friendly.

[0007] As a further improvement of the above solution, the preparation method of the emulsion is specifically operated as follows: S21 Add 30% deionized water and 60% sodium dodecyl sulfate to an emulsifying kettle, and stir for 10-20 min; S22 Continuously add isooctyl acrylate, methyl methacrylate, hydroxyethyl acrylate and acrylic carbamate modified monomer, and stir at 200-600 r / min for 40-50 min to obtain an emulsion. In the present invention, sodium dodecyl sulfate is added as an emulsifier to reduce the interfacial tension, making the monomers disperse to form fine droplets, so that the mixed solution forms a stable emulsion system. In addition, it improves the permeability and adhesion of the emulsion, enabling the emulsion to better penetrate into the substrate and form a relatively firm wood grain paper coating.

[0008] As a further improvement of the above solution, in the emulsion, the ratio of isooctyl acrylate, methyl methacrylate, hydroxyethyl acrylate and acrylic carbamate modified monomer is 50-90:40-75:1-4:1. In the present invention, through the free radical copolymerization reaction of acrylic monomers and the active monomer methyl methacrylate, the waterproof property of the obtained emulsion is improved.

[0009] As a further improvement of the above solution, the mass-volume ratio of ammonium persulfate to deionized water is 1:10, and ammonium persulfate is added to initiate the polymerization reaction.

[0010] As a further improvement of the above solution, the method for obtaining emulsion A in the polymerization reaction is specifically operated as follows: S41 Add deionized water to the reaction kettle, stir and heat up to 70 °C, then add sodium dodecyl sulfate, and continue to heat up to 80 °C; S42 Add 3% of the emulsion and 25% of the initiator, and keep the temperature for reaction for 30 - 40 min; S43 Dropwise add the remaining emulsion and the remaining initiator, and then keep the temperature for 2 h to obtain emulsion A; In the polymerization reaction of the present invention, the purpose of adding 3% of the emulsion and 25% of the initiator first for reaction is to make the emulsion pre-react for a period of time, so that the emulsion and initiator added dropwise later react more fully, thereby improving the conversion efficiency of the emulsion.

[0011] As a further improvement of the above solution, during the process of dropwise adding the remaining emulsion and the remaining initiator, the reaction temperature is 84 - 86 °C, the dropwise addition time is 3 - 4 h, and the temperature for keeping the temperature is 86 - 88 °C.

[0012] As a further improvement of the above solution, transfer emulsion A to a degassing kettle, cool down to 75 °C, add tert-butyl hydroperoxide, and then dropwise add vitamin C after 5 min, keep the temperature for 20 min, and obtain emulsion B through redox reaction. In the present invention, vitamin C is added to improve the workability of the emulsion mixture. A large number of strongly polar groups such as carboxyl and hydroxyl groups in vitamin C improve the dispersion and flow properties of each component in the emulsion through surface active actions such as adsorption, dispersion, and wetting. Tert-butyl hydroperoxide plays a role in initiating the polymerization reaction of acrylate monomers, while vitamin C plays a role in modification to improve the fluidity of the emulsion.

[0013] As a further improvement of the above solution, after the heat preservation is completed, steam degassing is carried out. The degassing temperature is 70 - 75 °C, the degassing pressure is -0.07 MPa, an antifoaming agent is added during the degassing process to prevent boiling over, and after degassing, it is cooled down to below 45 °C, filtered and discharged to obtain a water-based environmental protection emulsion. The solid content of the water-based environmental protection emulsion is 44% - 46%, the viscosity measured by a No. 4 Zahn viscosity cup is 30 - 40 s, and the pH is 7 - 9.

[0014] As a further improvement of the above solution, the weight parts composition of the water-based environmental protection emulsion is as follows: 20-25 parts of isooctyl acrylate, 15-20 parts of methyl methacrylate, 0.6-1 part of hydroxyethyl acrylate, 2-4 parts of sodium dodecyl sulfate, 0.2-0.5 part of acrylate carbamate modified monomer, 0.1-0.5 part of ammonium persulfate, 0.01-0.05 part of tert-butyl hydroperoxide, 0.02-0.04 part of vitamin C, and 53-57 parts of deionized water.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The preparation method of the present invention can produce a water-based environmental protection emulsion with good stability, glossiness, adhesion fastness, water resistance and weather resistance, and low volatile organic compound content. The preparation method is simple, efficient, environmentally friendly, and has broad application prospects and market value. Description of the Drawings

[0016] Figure 1 The figure shows a flow chart of a preparation method of a water-based environmental protection emulsion for a wood grain paper coating provided by the present invention. Detailed Embodiments

[0017] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments. The additional aspects and advantages of the present invention will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present invention. It should be understood that the following description is only used to explain the present invention and is not used to limit the present invention.

[0018] As used herein, the terms "comprising", "including", "containing" or any other variation thereof are intended to cover non-exclusive inclusion. For example, a composition, step, method, article or device containing the listed elements is not necessarily limited to those elements, but may include other elements not explicitly listed or elements inherent to such composition, step, method, article or device.

[0019] When an equivalent, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values and lower preferred values, this should be understood to specifically disclose all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is separately disclosed. For example, when the range "1 to 5" is disclosed, the described range should be interpreted to include the ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values and all integers and fractions within the range.

[0020] The following will describe in detail the specific embodiments of the present invention. Example 1

[0021] This example provides a preparation method of an environmentally friendly aqueous emulsion for wood grain paper coating, which includes the following steps: S1 Prepare an acrylic carbamate modified monomer by mixing hydroxyethyl acrylate, 2,4-toluene diisocyanate and diethanolamine in a ratio of 0.5:0.5:1.2.

[0022] The preparation method of the acrylic carbamate modified monomer is as follows: S11 Dehydrate hydroxyethyl acrylate.

[0023] S12 Heat 2,4-toluene diisocyanate to 65°C in a container. Under stirring conditions, drop the dehydrated hydroxyethyl acrylate into 2,4-toluene diisocyanate. After dropping, keep the temperature for 3.5 h to obtain a mixed solution.

[0024] S13 Cool down to 40°C. Under stirring conditions, drop the mixed solution into diethanolamine with a mass fraction of 30% diluted with acetone. After dropping, keep the temperature for 2.5 h.

[0025] S14 Remove acetone under reduced pressure to obtain the acrylic carbamate modified monomer.

[0026] In this example, the acrylic carbamate modified monomer is used to participate in the copolymerization reaction with the acrylate emulsion, overcoming the problem of formaldehyde release when using hydroxymethylacrylamide to crosslink with the acrylate emulsion, making the prepared emulsion free of formaldehyde release and more environmentally friendly.

[0027] S2 Prepare an emulsion by taking deionized water, sodium dodecyl sulfate, isooctyl acrylate, methyl methacrylate, hydroxyethyl acrylate and the acrylic carbamate modified monomer, and set it aside.

[0028] The preparation method of the emulsion is as follows: S21 Add 30% of deionized water and 60% of sodium dodecyl sulfate to the emulsification kettle and stir for 15 min.

[0029] S22 Continuously add 23.8 parts of isooctyl acrylate, 18.7 parts of methyl methacrylate, 0.8 part of hydroxyethyl acrylate and 0.4 part of the acrylic carbamate modified monomer, and stir at 300 r / min for 45 min to obtain an emulsion.

[0030] S3 Dilute 0.3 part of ammonium persulfate with deionized water to obtain an initiator and set it aside. The mass-volume ratio of ammonium persulfate to deionized water is 1:10.

[0031] In S4, the remaining deionized water, the remaining sodium dodecyl sulfate, the emulsion and the initiator are added into a reaction kettle for polymerization reaction to obtain emulsion A.

[0032] The method for obtaining emulsion A through the polymerization reaction is specifically operated as follows: In S41, deionized water is added into the reaction kettle. After stirring and heating up to 70°C, sodium dodecyl sulfate is added, and the temperature is continuously raised to 80°C.

[0033] In S42, 3% of the emulsion and 25% of the initiator are added, and the reaction is carried out under insulation for 30 min. In the polymerization reaction of this example, the purpose of adding 3% of the emulsion and 25% of the initiator for reaction first is to make the emulsion pre-react for a period of time, so that the emulsion and the initiator added dropwise later react more fully, thereby improving the conversion efficiency of the emulsion.

[0034] In S43, after the remaining emulsion and the remaining initiator are added dropwise, the mixture is kept warm for 2 h to obtain emulsion A. During the process of adding the remaining emulsion and the remaining initiator dropwise, the reaction temperature is 85°C, the dropping time is 3.5 h, and the insulation temperature is 87°C.

[0035] In S5, the emulsion A is transferred to a degassing kettle. After the temperature is lowered to 75°C, 0.035 parts of tert-butyl hydroperoxide are added. After 5 min, 0.025 parts of vitamin C are added dropwise, and the mixture is kept warm for 20 min to obtain emulsion B through redox reaction.

[0036] After the insulation is completed, emulsion B is subjected to steam degassing treatment. The degassing temperature is 70°C, the degassing pressure is -0.07 MPa. During the degassing process, an antifoaming agent is added to prevent boiling over. After degassing, the temperature is lowered to below 45°C, and then it is filtered and discharged to obtain a water-based environmentally friendly emulsion. The solid content of the water-based environmentally friendly emulsion is 44%, the viscosity measured by a No. 4 Zahn cup is 30 s, and the pH is 8.

[0037] Through the preparation method of this example, the water-based environmentally friendly emulsion produced has the following composition in parts by weight: 23.8 parts of isooctyl acrylate, 18.7 parts of methyl methacrylate, 0.8 parts of hydroxyethyl acrylate, 3.5 parts of sodium dodecyl sulfate, 0.4 parts of acrylate carbamate modified monomer, 0.3 parts of ammonium persulfate, 0.035 parts of tert-butyl hydroperoxide, 0.025 parts of vitamin C, and 56 parts of deionized water. Example 2

[0038] This example provides a preparation method of a water-based environmentally friendly emulsion for a wood grain paper coating, which includes the following steps: In S1, an acrylate carbamate modified monomer is prepared by mixing hydroxyethyl acrylate, 2,4-toluene diisocyanate and diethanolamine in a ratio of 0.5:0.5:1.2.

[0039] The preparation method of the acrylic carbamate modified monomer is specifically operated as follows: S11 Dehydrate hydroxyethyl acrylate.

[0040] S12 Heat 2,4-toluene diisocyanate to 65 °C in a container. Under stirring conditions, drop the dehydrated hydroxyethyl acrylate into 2,4-toluene diisocyanate. After the dropping is completed, keep the temperature for 3.5 h to obtain a mixed solution.

[0041] S13 Cool down to 40 °C. Under stirring conditions, drop the mixed solution into diethanolamine with a mass fraction of 30% diluted with acetone. After the dropping is completed, keep the temperature for 2.5 h.

[0042] S14 Remove acetone under reduced pressure to obtain the acrylic carbamate modified monomer.

[0043] In this example, the acrylic carbamate modified monomer is used to participate in the copolymerization reaction with the acrylate emulsion, overcoming the problem of formaldehyde release when using hydroxymethylacrylamide to crosslink with the acrylate emulsion, making the prepared emulsion free of formaldehyde release and more environmentally friendly.

[0044] S2 Prepare an emulsion by taking deionized water, sodium dodecyl sulfate, 20.6 parts of isooctyl acrylate, 16.5 parts of methyl methacrylate, 0.7 part of hydroxyethyl acrylate and 0.23 part of the acrylic carbamate modified monomer, and set it aside.

[0045] The preparation method of the emulsion is specifically operated as follows: S21 Add 30% of deionized water and 60% of sodium dodecyl sulfate to the emulsifying kettle and stir for 15 min.

[0046] S22 Continuously add isooctyl acrylate, methyl methacrylate, hydroxyethyl acrylate and the acrylic carbamate modified monomer, and stir at 300 r / min for 45 min to obtain an emulsion.

[0047] S3 Take 0.28 part of ammonium persulfate and dilute it with deionized water to obtain an initiator, and set it aside. The mass-volume ratio of ammonium persulfate to deionized water is 1:10.

[0048] S4 Add the remaining deionized water, the remaining sodium dodecyl sulfate, the emulsion and the initiator to the reaction kettle for polymerization reaction to obtain emulsion A.

[0049] The method for obtaining emulsion A by the polymerization reaction is specifically operated as follows: S41 Add deionized water to the reaction kettle. After stirring and heating to 70 °C, add sodium dodecyl sulfate and continue heating to 80 °C.

[0050] In S42, 3% of the emulsion and 25% of the initiator were added, and the reaction was carried out under insulation for 30 min. In the polymerization reaction of this example, the purpose of adding 3% of the emulsion and 25% of the initiator first for the reaction was to make the emulsion pre-react for a period of time, so that the subsequent added emulsion and initiator could react more fully, thereby improving the conversion efficiency of the emulsion.

[0051] In S43, after dropping the remaining emulsion and the remaining initiator, it was kept warm for 2 h to obtain emulsion A. During the process of dropping the remaining emulsion and the remaining initiator, the reaction temperature was 85 °C, the dropping time was 3.5 h, and the insulation temperature was 87 °C.

[0052] In S5, the emulsion A was transferred to a degassing kettle. After cooling to 75 °C, 0.03 parts of tert-butyl hydroperoxide was added. After 5 min, 0.02 parts of vitamin C was dropped, and it was kept warm for 20 min to obtain emulsion B by redox reaction.

[0053] After the insulation ended, emulsion B was subjected to steam degassing treatment. The degassing temperature was 70 °C, the degassing pressure was -0.07 MPa. During the degassing process, an antifoaming agent was added to prevent boiling over. After degassing, it was cooled to below 45 °C, filtered and discharged to obtain the water-based environmentally friendly emulsion. The solid content of the water-based environmentally friendly emulsion was 45%, the viscosity measured by a No. 4 Zahn viscosity cup was 35 s, and the pH was 9.

[0054] By the preparation method of this example, the water-based environmentally friendly emulsion produced had the following composition in parts by weight: 20.6 parts of isooctyl acrylate, 16.5 parts of methyl methacrylate, 0.7 parts of hydroxyethyl acrylate, 2.5 parts of sodium dodecyl sulfate, 0.23 parts of acrylate carbamate modified monomer, 0.28 parts of ammonium persulfate, 0.03 parts of tert-butyl hydroperoxide, 0.02 parts of vitamin C, and 53 parts of deionized water. Example 3

[0055] This example provides a preparation method of a water-based environmentally friendly emulsion for a wood grain paper coating, which includes the following steps: In S1, an acrylate carbamate modified monomer was prepared by mixing hydroxyethyl acrylate, 2,4-toluene diisocyanate and diethanolamine in a ratio of 0.5:0.5:1.2.

[0056] The preparation method of the acrylate carbamate modified monomer was specifically operated as follows: In S11, dehydration treatment was carried out on hydroxyethyl acrylate.

[0057] In S12, 2,4-toluene diisocyanate was heated to 65 °C in a container. Under stirring conditions, the dehydrated hydroxyethyl acrylate was dropped into 2,4-toluene diisocyanate. After dropping, it was kept warm for 3.5 h to obtain a mixed solution.

[0058] Cool S13 to 40°C. Under stirring conditions, add the mixed solution dropwise to diethanolamine with a mass fraction of 30% diluted with acetone. After the addition is complete, keep warm for 2.5 h.

[0059] Remove acetone under reduced pressure in S14 to obtain the acrylic carbamate modified monomer.

[0060] In this example, the acrylic carbamate modified monomer is used to participate in the copolymerization reaction with the acrylate emulsion, overcoming the problem of formaldehyde release when using hydroxymethylacrylamide to crosslink with the acrylate emulsion, making the prepared emulsion free of formaldehyde release and more environmentally friendly.

[0061] Take deionized water, sodium dodecyl sulfate, 23 parts of isooctyl acrylate, 17.6 parts of methyl methacrylate, 0.75 part of 2-hydroxyethyl acrylate and 0.33 part of the acrylic carbamate modified monomer to prepare an emulsion, and set it aside.

[0062] The preparation method of the emulsion is specifically operated as follows: Add 30% of deionized water and 60% of sodium dodecyl sulfate to the emulsifying kettle and stir for 15 min in S21.

[0063] Continue to add isooctyl acrylate, methyl methacrylate, 2-hydroxyethyl acrylate and the acrylic carbamate modified monomer, and stir for 45 min under the condition of 300 r / min to obtain the emulsion in S22.

[0064] Take 0.41 part of ammonium persulfate and dilute it with deionized water to obtain an initiator, and set it aside. The mass-volume ratio of ammonium persulfate to deionized water is 1:10.

[0065] Add the remaining deionized water, the remaining sodium dodecyl sulfate, the emulsion and the initiator to the reaction kettle for polymerization reaction to obtain emulsion A.

[0066] The method for obtaining emulsion A by the polymerization reaction is specifically operated as follows: Add deionized water to the reaction kettle. After stirring and heating to 70°C, add sodium dodecyl sulfate and continue heating to 80°C in S41.

[0067] Add 3% of the emulsion and 25% of the initiator, and keep the reaction warm for 30 min. In the polymerization reaction of this example, the purpose of adding 3% of the emulsion and 25% of the initiator for reaction first is to make the emulsion pre-react for a period of time, so that the subsequent added emulsion and initiator react more fully, thereby improving the conversion efficiency of the emulsion.

[0068] After adding the remaining emulsion and the remaining initiator dropwise and holding for 2 h, emulsion A was obtained. During the process of adding the remaining emulsion and the remaining initiator dropwise, the reaction temperature was 85 °C, the dropping time was 3.5 h, and the holding temperature was 87 °C.

[0069] S5 Transfer the emulsion A to a degassing kettle, cool it to 75 °C, add 0.032 parts of tert-butyl hydroperoxide, and after 5 min, add 0.032 parts of vitamin C dropwise, and hold for 20 min to obtain emulsion B by redox reaction.

[0070] S6 After the holding is completed, perform steam degassing treatment on emulsion B. The degassing temperature is 70 °C, the degassing pressure is -0.07 MPa, and an antifoaming agent is added during the degassing process to prevent boiling over. After degassing, cool it to below 45 °C, filter and discharge to obtain a water-based environmentally friendly emulsion. The solid content of the water-based environmentally friendly emulsion is 46%, the viscosity measured by a No. 4 Zahn viscosity cup is 40 s, and the pH is 8.5.

[0071] By the preparation method of this example, the water-based environmentally friendly emulsion produced has the following composition in parts by weight: 23 parts of isooctyl acrylate, 17.6 parts of methyl methacrylate, 0.75 parts of hydroxyethyl acrylate, 3.1 parts of sodium dodecyl sulfate, 0.33 parts of acrylate carbamate modified monomer, 0.41 parts of ammonium persulfate, 0.032 parts of tert-butyl hydroperoxide, 0.032 parts of vitamin C, and 57 parts of deionized water.

[0072] Taking the commercially available emulsion for wood grain paper coating as a comparative example, the gloss, number of rubbing resistance, heat pressing resistance, water resistance, solvent resistance, and VOC content of the water-based environmentally friendly emulsions of Examples 1-3 were detected. The specific detection process will not be elaborated, and the detection results are as follows: For the emulsion of Comparative Example 1, the gloss at a 60° angle is 35, the rubbing resistance is 200 times, the heat pressing temperature at 4 MPa for 1 s is 220 °C, the water resistance is no penetration for 2 h, the butanone rubbing resistance is 50 times, and the VOC content is 268 ppm; for the water-based environmentally friendly emulsion of Example 1, the gloss at a 60° angle is 46, the rubbing resistance is 330 times, the heat pressing temperature at 4 MPa for 1 s is 280 °C, the water resistance is no penetration for 4 h, the butanone rubbing resistance is 83 times, and the VOC content is 69 ppm; for the emulsion of Comparative Example 2, the gloss at a 60° angle is 37, the rubbing resistance is 265 times, the heat pressing temperature at 4 MPa for 1 s is 245 °C, the water resistance is no penetration for 2.5 h, the butanone rubbing resistance is 60 times, and the VOC content is 134 ppm; for the emulsion of Comparative Example 3, the gloss at a 60° angle is 41, the rubbing resistance is 290 times, the heat pressing temperature at 4 MPa for 1 s is 265 °C, the water resistance is no penetration for 3 h, the butanone rubbing resistance is 75 times, and the VOC content is 92 ppm.

[0073] The above results prove that by using the preparation method of the present invention, a water-based environmental protection emulsion with good stability, gloss, adhesion fastness, water resistance and weather resistance, and low volatile organic compound content can be produced, which can meet the high-quality requirements of the wood grain paper coating. The preparation method is simple, efficient, environmentally friendly, and has broad application prospects and market value.

[0074] The above embodiments are only the preferred embodiments of the present invention. Any simple modification, modification and alternative change made to the above embodiments based on the technical essence of the present invention all fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing an aqueous environmentally friendly emulsion for wood grain paper coating, characterized in that: The following steps are involved: S1 is prepared by mixing hydroxyethyl acrylate, 2,4-toluene diisocyanate and diethanolamine in a ratio of 0.5-1.5:0.5-1:1-1.5 to obtain an acrylic urethane modified monomer; S2: Deionized water, sodium lauryl sulfate, isooctyl acrylate, methyl methacrylate, hydroxyethyl acrylate and urethane modified monomer are prepared to obtain an emulsion for later use; S3: dilute ammonium persulfate with deionized water to obtain an initiator for later use; S4: taking the remaining deionized water, the remaining sodium dodecyl sulfate, the emulsion and the initiator and adding them into the reactor to carry out polymerization reaction to obtain emulsion A; S5: transferring the emulsion A to a degassing kettle, adding tert-butyl hydroperoxide and vitamin C, and performing redox reaction to obtain emulsion B; S6 performs steam degassing treatment on the emulsion B, and then cools and filters to obtain an aqueous environmentally friendly emulsion.

2. The method for preparing the water-based environmentally friendly emulsion for wood grain paper coating according to claim 1, characterized in that: The preparation method of the acrylic acid urethane modified monomer is specifically performed as follows: S11 dehydrates hydroxyethyl acrylate; S12: heating 2,4-toluene diisocyanate to 65-70° C. in a container, and adding the dehydrated hydroxyethyl acrylate dropwise to the 2,4-toluene diisocyanate under stirring. After the addition is completed, the mixture is kept warm for 3.5 hours to obtain a mixed solution. S13 cools the mixture to 35-40°C, and under stirring, drops the mixture into 30% diethanolamine diluted with acetone, and keeps the mixture warm for 2.5 hours after the addition is complete; S14 removes acetone under reduced pressure to obtain an acrylic acid urethane modified monomer.

3. The method for preparing the water-based environmentally friendly emulsion for wood grain paper coating according to claim 1, characterized in that: The method for preparing the emulsion is specifically performed as follows: S21: Add 30% deionized water and 60% sodium dodecyl sulfate to the emulsification kettle and stir for 10-20 minutes; S22 continues to add isooctyl acrylate, methyl methacrylate, hydroxyethyl acrylate and acrylic acid carbamate modified monomers, and stir at 200-600 r / min for 40-50 min to obtain an emulsion.

4. The method for preparing the water-based environmentally friendly emulsion for wood grain paper coating according to claim 3, characterized in that: In the emulsion, the ratio of isooctyl acrylate, methyl methacrylate, hydroxyethyl acrylate and urethane acrylic acid modified monomer is 50-90:40-75:1-4:

1.

5. The method for preparing the water-based environmentally friendly emulsion for wood grain paper coating according to claim 1, characterized in that: The mass volume ratio of the ammonium persulfate to deionized water is 1:

10.

6. The method for preparing the water-based environmentally friendly emulsion for wood grain paper coating according to claim 1, characterized in that: The method for obtaining emulsion A through polymerization reaction is specifically performed as follows: S41 Add deionized water to the reactor, stir and heat to 70°C, then add sodium dodecyl sulfate, and continue to heat to 80°C; S42 adds 3% emulsion and 25% initiator, and keeps the reaction for 30-40 minutes; S43 was added dropwise with the remaining emulsion and the remaining initiator, and then kept warm for 2 hours to obtain emulsion A.

7. The method for preparing the water-based environmentally friendly emulsion for wood grain paper coating according to claim 6, characterized in that: During the process of dripping the remaining emulsion and the remaining initiator, the reaction temperature is 84-86°C, the dripping time is 3-4h, and the insulation temperature is 86-88°C.

8. The method for preparing the water-based environmentally friendly emulsion for wood grain paper coating according to claim 1, characterized in that: The emulsion A was transferred to a degassing kettle, cooled to 75°C, tert-butyl hydroperoxide was added, vitamin C was added dropwise after 5 minutes, and the mixture was kept warm for 20 minutes, and then subjected to oxidation and reduction to obtain emulsion B.

9. The method for preparing the water-based environmentally friendly emulsion for wood grain paper coating according to claim 1, characterized in that: After the insulation is completed, steam degassing is carried out, the degassing temperature is 70-75°C, the degassing pressure is -0.07MPa, and a defoaming agent is added during the degassing process to prevent boiling. After degassing, the temperature is lowered to below 45°C, and the material is filtered to obtain a water-based environmentally friendly emulsion; The water-based environmentally friendly emulsion has a solid content of 44% to 46%, a viscosity of 30 to 40 seconds measured by a No. 4 Charpentier viscosity cup, and a pH of 7 to 9.

10. The method for preparing the water-based environmentally friendly emulsion for wood grain paper coating according to claim 9, characterized in that: The water-based environmentally friendly emulsion is composed of the following components in parts by weight: 20-25 parts of isooctyl acrylate, 15-20 parts of methyl methacrylate, 0.6-1 parts of hydroxyethyl acrylate, 2-4 parts of sodium lauryl sulfate, 0.2-0.5 parts of acrylic acid carbamate modified monomer, 0.1-0.5 parts of ammonium persulfate, 0.01-0.05 parts of tert-butyl hydroperoxide, 0.02-0.04 parts of vitamin C, and 53-57 parts of deionized water.

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