A method for preparing an ethyl cellulose / acrylate composite resin

Abstract

This invention relates to a method for preparing an ethyl cellulose / acrylate composite resin, belonging to the field of ceramic capacitor technology. The invention uses wood pulp as the starting material, haloethane as the reactant, and a eutectic solvent as the solvent and catalyst. The wood pulp reacts with haloethane under the catalysis of the eutectic solvent to generate ethyl cellulose. After reaching a certain degree of substitution, the ethyl cellulose precipitates and gradually dissolves in an extractant, separating the organic phase. A precipitant is added to obtain ethyl cellulose with low thermal decomposition residue suitable for MLCC processes. This ethyl cellulose is then composited with polyacrylic acid resin to obtain a mixed resin with excellent molding performance, low thermal decomposition residue, and good glue removal effect. This resin can be used as an organic carrier for the preparation of copper electron paste in MLCC production processes.

Description

Technical Field

[0001] This invention belongs to the field of ceramic capacitor technology, specifically relating to a method for preparing an ethyl cellulose / acrylate composite resin. Background Technology

[0002] Multilayer ceramic chip capacitors (MLCCs) have important applications in mobile phones, audio equipment, and automobiles, and are increasingly trending towards lower power consumption, miniaturization, and higher capacitance. Currently, in MLCC manufacturing processes, Cu electrodes, with their excellent conductivity, are gradually replacing precious metal electrodes as the mainstream research direction. However, the oxidation properties of Cu mean that the debinding and sintering process of the electronic paste can only be carried out in a nitrogen atmosphere. In China, the debinding stage of copper electronic paste for MLCCs requires humidification to promote the thermal decomposition of the organic carrier and debinding, facing the practical production problem of being unable to complete debinding and proper sintering of copper electronic paste under a nitrogen atmosphere, which seriously affects product quality.

[0003] Ethyl cellulose (EC) is an ethyl ether of cellulose, possessing excellent wetting, adhesive, and film-forming properties. It is widely used as a thickener in the preparation of silver electronic pastes. However, in copper electronic pastes, EC suffers from unstable thermal decomposition performance, high thermal decomposition residue, and poor debinding and sintering effects. The main reasons are: in the traditional process of synthesizing EC using toluene as a solvent and a sodium hydroxide catalytic system, the cellulose is severely degraded due to the strongly alkaline environment; moreover, because it is a heterogeneous reaction, the substitution reaction is uneven, resulting in significant differences in the molecular structure of the products, making it difficult to control the molecular weight and molecular weight distribution, which greatly affects the solubility and thermal decomposition performance; simultaneously, the separation of the reaction product EC and the cellulose raw material is difficult, making the post-processing process complex.

[0004] Therefore, solving the problems of thermal decomposition residue and adhesive removal in organic carriers of copper electronic pastes using EC as a thickener is of great production significance and practical value. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems existing in the prior art and provide a method for preparing ethyl cellulose / acrylate composite resin.

[0006] This invention is achieved through the following technical solution:

[0007] The present invention aims to provide a method for preparing ethyl cellulose / acrylate composite resin, comprising the following steps: reacting wood pulp and haloethane in a eutectic solvent (DES), extracting, precipitating, and obtaining ethyl cellulose; then melting and mixing the obtained ethyl cellulose with polyacrylic acid resin to obtain the ethyl cellulose / acrylate composite resin; wherein the eutectic solvent includes choline chloride, urea, and sodium hydroxide.

[0008] This invention involves reacting wood pulp and haloethane in a eutectic solvent containing choline chloride, urea, and sodium hydroxide to obtain ethyl cellulose. Extraction is then performed to separate unreacted pulp and low-substituted ethyl cellulose from the high-substituted ethyl cellulose product. Precipitation further removes low-molecular-weight ethyl cellulose, yielding high-purity ethyl cellulose. This is then compounded with polyacrylic acid resin. The polyacrylate, after being dissolved in the solvent, effectively increases the viscosity of the electronic paste and exhibits certain rheological properties. After printing, the paste maintains a good shape, forming a hard film, and completely decomposes without leaving ash during the debinding and sintering stage. The resulting ethyl cellulose / acrylate composite resin can be directly used as an organic carrier for copper electronic pastes in MLCC casting processes.

[0009] Preferably, the degree of polymerization of the wood pulp is 350-850. More preferably, the degree of polymerization of the wood pulp is 400-800.

[0010] If the degree of polymerization of wood pulp is too high, the reaction will be difficult; if the degree of polymerization is too low, the performance will be poor. Therefore, wood pulp with a degree of polymerization of 350-850 is preferred.

[0011] This invention does not limit the source of raw materials or the preparation method of wood pulp. For example, wood pulp can be softwood pulp or hardwood pulp, and the preparation method can be, for example, the sulfate process.

[0012] Preferably, the wood pulp contains >90% α-cellulose, ≤0.1% ash, and <1% lignin.

[0013] Preferably, the mass ratio of the wood pulp to the volume ratio of the haloethane is 1 g: (4-6) mL.

[0014] Preferably, the haloethane includes bromoethane.

[0015] Preferably, the mass ratio of the wood pulp to the eutectic solvent is 1:(8-15).

[0016] Preferably, in the eutectic solvent, the mass ratio of choline chloride, urea and sodium hydroxide is 1:(2-3):(1.5-5).

[0017] Preferably, the reaction temperature is 100℃-130℃ and the time is 0.5h-3h.

[0018] Preferably, the reaction is carried out under closed conditions with stirring.

[0019] Preferably, the extractant used in the extraction includes toluene.

[0020] Preferably, the precipitant used for precipitation includes diethyl ether.

[0021] This invention utilizes the strong solubility and catalytic properties of DES to enable a homogeneous reaction between cellulose and haloethanes in a dissolved state, resulting in a product with good structural uniformity and low cellulose degradation. After the reaction proceeds to a certain extent, toluene, a good solvent for EC, is added for extraction. Highly substituted ECs are transferred from the strongly polar DES to toluene. Since cellulose and low-substituted ECs are insoluble in toluene, the product has high purity and a relatively high degree of substitution. A precipitant, such as diethyl ether, is added to the toluene to precipitate the high molecular weight product, thus separating it from some of the low molecular weight products. The diethyl ether and toluene used in the process can be recycled. There are no special requirements for the amount of diethyl ether added as a precipitant; it is sufficient if no further precipitation occurs when diethyl ether is added to the organic solvent.

[0022] Preferably, the temperature is lowered to 70℃-90℃ before extraction, and the organic solvent is added and stirred thoroughly to fully extract ethyl cellulose into the organic phase.

[0023] Preferably, the mass ratio of the eutectic solvent to the volume ratio of the extractant is 1 g:(1-3) mL.

[0024] Preferably, the mass ratio of the ethyl cellulose to the polyacrylic acid resin is 1:(0.5-3).

[0025] The ethyl cellulose obtained by this invention has an ethoxy content of greater than 50%.

[0026] The present invention has the following beneficial effects:

[0027] This invention uses wood pulp as the starting material, haloethane as the reactant, and choline chloride-urea-sodium hydroxide eutectic solvent as the solvent and catalyst. Wood pulp reacts with haloethane under DES catalysis to produce ethyl cellulose (EC). After reaching a certain degree of substitution, EC precipitates from DES and gradually dissolves in the extractant, separating the organic phase. A precipitant is added to obtain EC with low thermal decomposition residue suitable for MLCC processes. This EC is then compounded with polyacrylic acid resin to obtain a mixed resin with excellent molding performance, low thermal decomposition residue, and good glue removal effect, which can be used as an organic carrier for the preparation of copper electron paste in MLCC production processes. The preparation method of this invention is simple to operate, environmentally friendly, and easy to implement for industrial production. The DES after separating the organic phase can be reused, and the solvent and precipitant can be reused, reducing production costs. Attached Figure Description

[0028] Figure 1 The thermal decomposition residual curve of the ethyl cellulose / acrylate composite resin prepared in Example 2 is shown.

[0029] Figure 2 A photograph of the ethyl cellulose / acrylate composite resin prepared in Example 3;

[0030] Figure 3 The thermal decomposition residual curves of the ethyl cellulose / acrylate composite resin prepared in Example 7 and different solvents are compared. Detailed Implementation

[0031] To better illustrate the objectives, technical solutions, and advantages of this invention, the invention will be further described below with reference to specific embodiments. Those skilled in the art should understand that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0032] Unless otherwise specified, the experimental methods used in the examples are conventional methods; the materials and reagents used are commercially available unless otherwise specified.

[0033] In this embodiment of the invention, the raw materials, softwood pulp and hardwood pulp, are obtained by the sulfate process. The polyacrylic acid resin is Degussa solid acrylic resin DEGALAN LP65 / 12.

[0034] Example 1

[0035] A method for preparing an ethyl cellulose / acrylate composite resin includes the following steps:

[0036] 5g of softwood pulp with a degree of polymerization of 500 and 25mL of bromoethane were mixed with 50g of eutectic solvent. The mixture was sealed and heated to 110℃ and stirred for 1h. After cooling to 80℃, 50mL of toluene was added and the mixture was stirred for another 0.5h. The organic phase was separated and dried with anhydrous sodium sulfate. Diethyl ether was added to precipitate 4.3g of ethyl cellulose.

[0037] Then, 2g of the obtained ethyl cellulose and 3g of polyacrylic acid resin are melt-blended at 180°C, cooled, and pulverized to obtain the ethyl cellulose / acrylate composite resin.

[0038] The softwood pulp contains 96% α-cellulose, 0.1% ash, and less than 1% lignin; the eutectic solvent is composed of choline chloride, urea, and sodium hydroxide in a mass ratio of 1:2:3.

[0039] Tests showed that the obtained ethyl cellulose / acrylate composite resin had a thermal decomposition residue of <0.3% at 900℃.

[0040] Example 2

[0041] A method for preparing an ethyl cellulose / acrylate composite resin includes the following steps:

[0042] 5g of softwood pulp with a degree of polymerization of 400 and 25mL of bromoethane were mixed with 50g of eutectic solvent. The mixture was sealed and heated to 110℃ and stirred for 1h. After cooling to 80℃, 50mL of toluene was added and the mixture was stirred for another 0.5h. The organic phase was separated and dried with anhydrous sodium sulfate. Diethyl ether was added to precipitate 4.5g of ethyl cellulose.

[0043] Then, 2g of the obtained ethyl cellulose and 4g of polyacrylic acid resin are melt-blended at 180°C, cooled, and pulverized to obtain the ethyl cellulose / acrylate composite resin.

[0044] The softwood pulp contains 96% α-cellulose, 0.1% ash, and less than 1% lignin; the eutectic solvent is composed of choline chloride, urea, and sodium hydroxide in a mass ratio of 1:2:3.

[0045] Tests showed that the obtained ethyl cellulose / acrylate composite resin had a thermal decomposition residue of <0.2% at 900℃. Figure 1 The image shows the thermal decomposition residual curve of the ethyl cellulose / acrylate composite resin prepared in this embodiment.

[0046] Example 3

[0047] A method for preparing an ethyl cellulose / acrylate composite resin includes the following steps:

[0048] 5g of softwood pulp with a degree of polymerization of 600 and 25mL of bromoethane were mixed with 60g of eutectic solvent. The mixture was sealed and heated to 110℃ and stirred for 1h. After cooling to 80℃, 70mL of toluene was added and the mixture was stirred for another 0.5h. The organic phase was separated and dried with anhydrous sodium sulfate. Diethyl ether was added to precipitate 4.4g of ethyl cellulose.

[0049] Then, 2g of the obtained ethyl cellulose and 6g of polyacrylic acid resin were melt-blended at 180°C, cooled, and pulverized to obtain the ethyl cellulose / acrylate composite resin.

[0050] The softwood pulp contains 96% α-cellulose, 0.1% ash, and less than 1% lignin; the eutectic solvent is composed of choline chloride, urea, and sodium hydroxide in a mass ratio of 1:2:3.

[0051] Figure 2 The image shows the ethyl cellulose / acrylate composite resin prepared in this embodiment. Testing showed that the thermal decomposition residue of the obtained ethyl cellulose / acrylate composite resin at 900°C was <0.35%.

[0052] Example 4

[0053] A method for preparing an ethyl cellulose / acrylate composite resin includes the following steps:

[0054] 5g of softwood pulp with a degree of polymerization of 600 and 25mL of bromoethane were mixed with 75g of eutectic solvent. The mixture was sealed and heated to 110℃ and stirred for 1h. After cooling to 80℃, 80mL of toluene was added and the mixture was stirred for another 0.5h. The organic phase was separated and dried with anhydrous sodium sulfate. Diethyl ether was added to precipitate 4.6g of ethyl cellulose.

[0055] Then, 2g of the obtained ethyl cellulose and 6g of polyacrylic acid resin were melt-blended at 180°C, cooled, and pulverized to obtain the ethyl cellulose / acrylate composite resin.

[0056] The softwood pulp contains 96% α-cellulose, 0.1% ash, and less than 1% lignin; the eutectic solvent is composed of choline chloride, urea, and sodium hydroxide in a mass ratio of 1:2:3.

[0057] Tests showed that the obtained ethyl cellulose / acrylate composite resin had a thermal decomposition residue of <0.35% at 900℃.

[0058] Example 5

[0059] A method for preparing an ethyl cellulose / acrylate composite resin includes the following steps:

[0060] 5g of softwood pulp with a degree of polymerization of 600 and 25mL of bromoethane were mixed with 40g of eutectic solvent. The mixture was sealed and heated to 110℃ and stirred for 1h. After cooling to 80℃, 50mL of toluene was added and the mixture was stirred for another 0.5h. The organic phase was separated and dried with anhydrous sodium sulfate. Diethyl ether was added to precipitate 4.1g of ethyl cellulose.

[0061] Then, 2g of the obtained ethyl cellulose and 2g of polyacrylic acid resin are melt-blended at 180°C, cooled, and pulverized to obtain the ethyl cellulose / acrylate composite resin.

[0062] The softwood pulp contains 93% α-cellulose, 0.1% ash, and less than 1% lignin; the eutectic solvent is composed of choline chloride, urea, and sodium hydroxide in a mass ratio of 1:2:4.

[0063] Tests showed that the obtained ethyl cellulose / acrylate composite resin had a thermal decomposition residue of <0.7% at 900℃.

[0064] Example 6

[0065] A method for preparing an ethyl cellulose / acrylate composite resin includes the following steps:

[0066] 5g of softwood pulp with a degree of polymerization of 700 and 25mL of bromoethane were mixed with 60g of eutectic solvent. The mixture was sealed and heated to 110℃ and stirred for 1h. After cooling to 80℃, 60mL of toluene was added and the mixture was stirred for another 0.5h. The organic phase was separated and dried with anhydrous sodium sulfate. Diethyl ether was added to precipitate 3.8g of ethyl cellulose.

[0067] Then, 3g of the obtained ethyl cellulose and 2g of polyacrylic acid resin are melt-blended at 180°C, cooled, and pulverized to obtain the ethyl cellulose / acrylate composite resin.

[0068] The softwood pulp contains 93% α-cellulose, 0.1% ash, and less than 1% lignin; the eutectic solvent is composed of choline chloride, urea, and sodium hydroxide in a mass ratio of 1:2:4.

[0069] Tests showed that the obtained ethyl cellulose / acrylate composite resin had a thermal decomposition residue of <0.8% at 900℃.

[0070] Example 7

[0071] A method for preparing an ethyl cellulose / acrylate composite resin includes the following steps:

[0072] 5g of softwood pulp with a degree of polymerization of 800 and 25mL of bromoethane were mixed with 70g of eutectic solvent. The mixture was sealed and heated to 110℃ and stirred for 1h. After cooling to 80℃, 90mL of toluene was added and the mixture was stirred for another 0.5h. The organic phase was separated and dried with anhydrous sodium sulfate. Diethyl ether was added to precipitate 4.0g of ethyl cellulose.

[0073] The 4g of ethyl cellulose obtained is then melt-blended with 2g of polyacrylic acid resin at 180°C, cooled, and pulverized to obtain the ethyl cellulose / acrylate composite resin.

[0074] The softwood pulp contains 93% α-cellulose, 0.1% ash, and less than 1% lignin; the eutectic solvent is composed of choline chloride, urea, and sodium hydroxide in a mass ratio of 1:2:4.

[0075] Tests showed that the obtained ethyl cellulose / acrylate composite resin had a thermal decomposition residue of <1% at 900℃. Figure 3 To compare the thermal decomposition residual curves of the ethyl cellulose / acrylate composite resin prepared in this embodiment with those in different solvents, from... Figure 3 As can be seen, the composite resin decomposes rapidly at around 400 degrees Celsius, and the thermal decomposition residue at 900 degrees Celsius is less than 1%.

[0076] Example 8

[0077] A method for preparing an ethyl cellulose / acrylate composite resin includes the following steps:

[0078] 5g of hardwood pulp with a degree of polymerization of 800 and 25mL of bromoethane were mixed with 70g of eutectic solvent. The mixture was sealed and heated to 110℃ and stirred for 1h. After cooling to 80℃, 90mL of toluene was added and the mixture was stirred for another 0.5h. The organic phase was separated and dried with anhydrous sodium sulfate. Diethyl ether was added to precipitate 3.6g of ethyl cellulose.

[0079] Then, 3g of the obtained ethyl cellulose and 3g of polyacrylic acid resin are melt-blended at 180°C, cooled, and pulverized to obtain the ethyl cellulose / acrylate composite resin.

[0080] The softwood pulp contains 93% α-cellulose, 0.1% ash, and less than % lignin; the eutectic solvent is composed of choline chloride, urea, and sodium hydroxide, with a mass ratio of choline chloride, urea, and sodium hydroxide of 1:2:4.

[0081] Tests showed that the obtained ethyl cellulose / acrylate composite resin had a thermal decomposition residue of <1% at 900℃.

[0082] Comparative Example 1

[0083] A method for preparing a composite resin includes the following steps:

[0084] 5g of softwood pulp with a degree of polymerization of 400 and 25mL of bromoethane were mixed with 50g of eutectic solvent. The mixture was sealed and heated to 110℃ and stirred for 1h. After cooling to 80℃, 50mL of toluene was added and the mixture was stirred for another 0.5h. The organic phase was separated and dried with anhydrous sodium sulfate. Diethyl ether was added to precipitate 4.5g of ethyl cellulose.

[0085] Then, 2g of the obtained ethyl cellulose and 4g of polybutyl acrylate resin were melt-blended at 180°C, cooled, and pulverized to obtain the composite resin.

[0086] The softwood pulp contains 96% α-cellulose, 0.1% ash, and less than 1% lignin; the eutectic solvent is composed of choline chloride, urea, and sodium hydroxide in a mass ratio of 1:2:4.

[0087] Tests showed that the thermal decomposition residue of the obtained composite resin at 900℃ was <3% and greater than 2%.

[0088] Comparative Example 2

[0089] A method for preparing an ethyl cellulose / acrylate composite resin includes the following steps:

[0090] Ethyl cellulose was prepared using a traditional method as follows: 5g of crushed cotton fiber was added to a reaction vessel, which was then evacuated and purged with nitrogen. 20mL of 50% liquid alkali and 60mL of toluene were added, and the mixture was alkalized at 45℃ for 0.5h. After alkalization, 120mL of chloroethane was added, and the mixture was stirred at 120℃ for etherification for 12h. Acetic acid was used to neutralize the ether to a pH of around 9. After repeated washing, the mixture was filtered and dried at 60℃ to obtain ethyl cellulose.

[0091] Then, 2g of the obtained ethyl cellulose and 4g of polyacrylic acid resin are melt-blended at 180°C, cooled, and pulverized to obtain the ethyl cellulose / acrylate composite resin.

[0092] Tests showed that the obtained ethyl cellulose / acrylate composite resin had a thermal decomposition residue of <6% and >5% at 900℃.

[0093] Comparative Example 3

[0094] A method for preparing an ethyl cellulose / acrylate composite resin includes the following steps:

[0095] 5g of softwood pulp with a degree of polymerization of 400 and 25mL of bromoethane were mixed with 50g of eutectic solvent. The mixture was sealed and heated to 110℃ and stirred for 1h. After cooling to 80℃, 50mL of toluene was added and the mixture was stirred for another 0.5h. The organic phase was separated and dried with anhydrous sodium sulfate. Diethyl ether was added to precipitate 4.5g of ethyl cellulose.

[0096] Then, 2g of the obtained ethyl cellulose and 4g of polyacrylic acid resin are melt-blended at 180°C, cooled, and pulverized to obtain the ethyl cellulose / acrylate composite resin.

[0097] The softwood pulp contains 96% α-cellulose, 0.1% ash, and less than 1% lignin; the eutectic solvent is composed of choline chloride and lactic acid in a mass ratio of 1:2.

[0098] Tests showed that the obtained ethyl cellulose / acrylate composite resin had a thermal decomposition residue of <5% and >4% at 900℃.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing an ethyl cellulose / acrylate composite resin, characterized in that, Includes the following steps: Wood pulp and haloethane are reacted in a eutectic solvent, extracted, and precipitated to obtain ethyl cellulose; the obtained ethyl cellulose is then melt-mixed with polyacrylic acid resin to obtain the ethyl cellulose / acrylate composite resin; the eutectic solvent includes choline chloride, urea, and sodium hydroxide; the polyacrylic acid resin is Degussa solid acrylic resin DEGALAN LP65 / 12.

2. The method for preparing the ethyl cellulose / acrylate composite resin according to claim 1, characterized in that, The degree of polymerization of the wood pulp is 350-850.

3. The method for preparing the ethyl cellulose / acrylate composite resin according to claim 1, characterized in that, The mass ratio of the wood pulp to the volume ratio of the haloethane is 1 g: (4-6) mL.

4. The method for preparing the ethyl cellulose / acrylate composite resin according to claim 1, characterized in that, The mass ratio of the wood pulp to the eutectic solvent is 1:(8-15).

5. The method for preparing the ethyl cellulose / acrylate composite resin according to claim 1, characterized in that, In the eutectic solvent, the mass ratio of choline chloride, urea and sodium hydroxide is 1:(2-3):(1.5-5).

6. The method for preparing the ethyl cellulose / acrylate composite resin according to claim 1, characterized in that, The reaction temperature is 100℃-130℃, and the time is 0.5h-3h.

7. The method for preparing the ethyl cellulose / acrylate composite resin according to claim 1, characterized in that, The extraction process uses toluene as the extractant.

8. The method for preparing the ethyl cellulose / acrylate composite resin according to claim 1, characterized in that, The precipitant used for precipitation includes diethyl ether.

9. The method for preparing the ethyl cellulose / acrylate composite resin according to claim 7, characterized in that, The mass ratio of the eutectic solvent to the volume ratio of the extractant is 1 g: (1-3) mL.

10. The method for preparing the ethyl cellulose / acrylate composite resin according to claim 1, characterized in that, The mass ratio of the ethyl cellulose to the polyacrylic acid resin is 1:(0.5-3).

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