CN110951212B - Preparation method of nano silicon dioxide modified melamine formaldehyde resin - Google Patents
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L61/00—Compositions of condensation polymers of aldehydes or ketones; Compositions of derivatives of such polymers
- C08L61/20—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen
- C08L61/30—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with heterocyclic and acyclic or carbocyclic compounds
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- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G12/00—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen
- C08G12/02—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes
- C08G12/26—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with heterocyclic compounds
- C08G12/34—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with heterocyclic compounds and acyclic or carbocyclic compounds
- C08G12/36—Ureas; Thioureas
- C08G12/38—Ureas; Thioureas and melamines
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Abstract
A preparation method of a nano silicon dioxide modified melamine formaldehyde resin is characterized by comprising the following steps: preparing 5% solution of nano silicon dioxide according to parts by weight, mixing 1-2 parts of the solution with 20 parts of polyethylene glycol, and obtaining a mixture A after 10 min; adjusting the pH value of 160 parts of formaldehyde to 9-10 by using 30% sodium hydroxide, sequentially adding 1 part of polyethylene glycol, 70 parts of melamine and 46 parts of urea, heating to 40 ℃, adding the mixture A, continuously heating to 75-80 ℃, keeping the pH value at 8.5-9.5, keeping the temperature at 75-80 ℃ for 2.5-3.5h, sampling, monitoring the cloud point, cooling to 40 ℃ when the cloud point is reached, and adjusting the pH value to 9-10 by using 30% sodium hydroxide to obtain the nano silicon dioxide modified melamine formaldehyde resin. The process is simple, and the prepared melamine formaldehyde resin has good flexibility, low free formaldehyde content and good environmental protection effect.
Description
Technical Field
The invention relates to a preparation method of melamine resin, in particular to a preparation method of nano silicon dioxide modified melamine formaldehyde resin.
Background
The melamine formaldehyde resin, abbreviated as MF in English, has the advantages of colorless transparency, heat resistance, wear resistance, flame retardance, stable product size and the like. However, the resin has the defects of relatively high hardness and high brittleness after being cured, and is not easy to bend, break, crack and the like after being used for surface finishing of products. In order to improve the brittleness and enhance the application performance of MF, researchers have performed a great deal of modification experimental work. Patent US4666948 improves the toughness of the resin by adding an alkyl metal or an organo aluminum to it. The ternary alcohol substance is added in the raw materials, so that the rebound resilience and the cracking resistance of the prepared foam are greatly improved. Brittleness is improved by replacing hydrogen atoms on melamine with flexible carbon chains. Patent 2012103535131 discloses a method for toughening and modifying melamine resin. The patent uses a compound containing any one or two of polyhydroxy, polycarboxyl and polyamino as a toughening agent to perform polycondensation reaction with methylol melamine, and introduces a flexible chain polymer into melamine formaldehyde resin, thereby reducing the crosslinking degree of the resin and improving the flexibility of the resin. The elongation at break of the toughened melamine formaldehyde resin is improved to 89.3 percent from the original 6.3 percent. Patent 2011102247170[16] discloses a water-soluble modified melamine formaldehyde impregnating resin and a preparation method and application thereof, and the preparation method comprises the following steps: the water-soluble methylated melamine-formaldehyde resin is prepared by carrying out addition polycondensation reaction on formaldehyde and melamine, etherifying with methanol, and compounding with penetrating agent, urea and other formaldehyde removing agents; the water-soluble acrylate emulsion toughening agent is prepared from an acrylate monomer and styrene by an emulsion polymerization method; the water-soluble polyurethane emulsion modifier is prepared by adopting toluene diisocyanate, polyether dihydroxy propionic acid and ethylenediamine through a self-emulsifying method; the three resins are mixed according to a certain weight ratio to prepare the water-soluble modified melamine formaldehyde resin. The resin can be used for impregnating paper edge banding and decorative paper in furniture and papermaking industries, and has the advantages of good flexibility, low residual formaldehyde content, long-term stability and the like. At present, the main adopted melamine resin toughening is mostly a plasticizing method. Adding alcohols such as: ethanol, ethylene glycol, polyvinyl alcohol or amide compounds (ethanol, ethylene glycol, polyvinyl alcohol, etc. are commonly used for alcohols, and N, N-Dimethylformamide (DMF), caprolactam (CPL), p-toluenesulfonamide (PTSA), etc. are commonly used for amides). Then some elastic emulsion such as butadiene styrene latex, aqueous polyurethane emulsion and nitrile-butadiene latex is added. The former method is added in a large amount to achieve the desired effect and adversely affects the heat resistance of the resin. The latter method adversely affects the surface gloss and transparency of the cured resin, which is unacceptable as a melamine resin for surface decoration.
Disclosure of Invention
The invention is based on the idea that by utilizing the rigid particle nano silicon dioxide, when the material is subjected to an external force, a stress concentration effect can be generated, a large number of silver grains are initiated by the particles, the matrix around the particles is forced to generate plastic deformation, and a large amount of impact energy is absorbed. Meanwhile, the existence of the rigid particles can also hinder the development of the silver streaks, passivate and stop the silver streaks, and also play a toughening effect. Good interfacial adhesion is a guarantee that the material has better mechanical properties.
The invention aims to overcome the problems of high brittleness, poor flexibility, complex preparation process and the like of the melamine formaldehyde resin in the prior art, and provides the preparation method of the nano silicon dioxide modified melamine formaldehyde resin with simple flow and convenient operation.
The purpose of the invention is realized by the following technical scheme: a preparation method of nano silicon dioxide modified melamine formaldehyde resin is characterized by comprising the following steps:
1) Preparing 5% solution of nano silicon dioxide according to parts by weight, then mixing 1-2 parts of nano silicon dioxide with 20 parts of polyethylene glycol for 10min to obtain a mixture A;
2) According to the weight parts, 160 parts of formaldehyde is adjusted to 9-10 by 30% sodium hydroxide, 1 part of polyethylene glycol, 70 parts of melamine and 46 parts of urea are sequentially added, the temperature is raised to 40 ℃, the mixture A in the step 1) is added, the temperature is continuously raised to 75-80 ℃, the pH value is kept within 8.5-9.5, the temperature is kept constant at 75-80 ℃ for 2.5-3.5h, the clouding point is sampled and monitored under the constant temperature state of 75-80 ℃, when the clouding point is reached, the temperature is lowered to 40 ℃, and the pH value is adjusted to 9-10 by 30% sodium hydroxide, so that the nano silicon dioxide modified melamine formaldehyde resin is obtained.
The preparation method of the nano silicon dioxide modified melamine formaldehyde resin has the beneficial effects that:
1) Rigid particle nano silicon dioxide is used as a toughening agent, a molecular chain of the nano silicon dioxide simultaneously contains a triazine ring and a flexible polyether chain segment, the toughening agent is added into melamine resin, the triazine ring structure of the toughening agent can participate in the curing reaction of the triamine resin, the flexible high molecular chain segment containing the polyether structure is introduced into the macromolecule of the resin, the crosslinking degree of the triamine resin is reduced, and the flexibility, the impact resistance and the flexibility of the triamine resin can be obviously improved. And the toughening agent participates in the curing reaction and is grafted to the main molecular chain, so that the original transparency and surface gloss of the melamine resin are not adversely affected. The water resistance, wear resistance and chemical resistance of the paint cannot be greatly and negatively influenced;
2) The surface of the nano silicon dioxide is rich in hydroxyl, but the nano silicon dioxide has small particle size, large specific surface area and very high surface energy, is extremely easy to agglomerate to form aggregate particles, and when the nano silicon dioxide is directly used as a modifier to be added into resin, the nano silicon dioxide does not play a role in modification, but influences the performance of the resin. Therefore, when the nano silicon dioxide is used for modifying the melamine formaldehyde resin, the flexible spacing matrix filler polyethylene glycol is added to improve the dispersibility of the nano silicon dioxide in the melamine resin and enhance the toughness of the resin, and the resin has low free formaldehyde content, strong flexibility and good environmental protection effect;
3) Simple process, convenient operation and low preparation cost.
Drawings
FIG. 1 is a graph showing the relationship between the amount of nano-silica added and the free formaldehyde content of melamine resin in examples 1-5;
FIG. 2 is a graph showing the relationship between the addition amount of the nano-silica and the elongation at break of the melamine resin obtained in examples 1 to 5;
FIG. 3 is a graph showing the Tg curves of the melamine resin and the amount of the added nanosilica obtained in examples 2-4.
Shown in the figure are: a: example 2; b: example 3; c: example 4.
Detailed Description
The present invention will be further described with reference to the following examples.
The invention relates to a preparation method of nano silicon dioxide modified melamine formaldehyde resin, which comprises the following steps:
1) Preparing 5% aqueous solution of nano silicon dioxide according to parts by weight, mixing 1-2 parts of nano silicon dioxide with 20 parts of polyethylene glycol, and obtaining polyethylene glycol silicon dioxide mixed solution after 10 min;
2) According to the weight parts, 160 parts of formaldehyde is adjusted to 9-10 by 30% sodium hydroxide, 1 part of polyethylene glycol, 70 parts of melamine and 46 parts of urea are sequentially added, the temperature is raised to 40 ℃, the polyethylene glycol-silicon dioxide mixed solution in the step 1) is added, the temperature is continuously raised to 75-80 ℃, the pH value is kept at 8.5 to 9.5, the temperature is kept constant at 75-80 ℃ for 2.5-3.5 hours, the cloud point is sampled and monitored in the constant temperature state of 75-80 ℃, when the cloud point is reached, the temperature is lowered to 40 ℃, the pH value is adjusted to 9-10 by 30% sodium hydroxide, and the nano-silicon dioxide modified melamine-formaldehyde resin is obtained.
Example 1: the preparation method of the nano silica modified melamine formaldehyde resin of embodiment 1 comprises the following steps:
1) Preparing 5% aqueous solution of nano silicon dioxide according to parts by weight, slowly putting 1 part of the aqueous solution into a three-neck flask provided with a stirrer and a thermometer, adding 20 parts of polyethylene glycol, and mixing for 10min to obtain polyethylene glycol-silicon dioxide mixed solution;
2) According to parts by weight, 160 parts of formaldehyde is adjusted to be 9-10 by 30% of sodium hydroxide in a three-neck flask with a stirrer and a thermometer, 1 part of polyvinyl alcohol, 70 parts of melamine and 46 parts of urea are sequentially added, the temperature is raised to 40 ℃, the polyethylene glycol and silicon dioxide mixed solution in the step 1) is added, the temperature is raised to 78 ℃, the pH value is kept at 8.5, the temperature is kept for a period of time, the reaction end point is determined by adopting a turbid experimental method, and if the temperature reaches the requirement, the temperature is quickly lowered, so that the light yellow melamine resin solution is obtained.
Example 2: the method for preparing the nano-silica modified melamine formaldehyde resin of embodiment 2 comprises the steps of:
1) Preparing 5% aqueous solution of nano silicon dioxide according to parts by weight, slowly putting 1.2 parts of nano silicon dioxide into a three-neck flask with a stirrer and a thermometer, and then putting 20 parts of polyethylene glycol for mixing for 10min to obtain polyethylene glycol-silicon dioxide mixed solution;
2) According to parts by weight, 160 parts of formaldehyde is added into a three-neck flask provided with a stirrer and a thermometer, 30% sodium hydroxide is used for adjusting the pH value to 9-10, 1 part of polyvinyl alcohol, 70 parts of melamine and 46 parts of urea are sequentially added, the temperature is raised to 40 ℃, the polyethylene glycol and silicon dioxide mixed solution obtained in the step 1) is added, the temperature is raised to 78 ℃, the pH value is kept at 9, the temperature is kept for a period of time, the reaction endpoint is determined by adopting a turbid experimental method, and if the requirement is met, the temperature is rapidly reduced, so that the light yellow melamine resin solution is obtained.
Example 3: the preparation method of the nano silica modified melamine formaldehyde resin of embodiment 3 comprises the following steps:
1) Preparing 5% aqueous solution of nano silicon dioxide according to parts by weight, slowly putting 1.4 parts of nano silicon dioxide into a three-neck flask provided with a stirrer and a thermometer, and then putting 20 parts of polyethylene glycol and mixing for 10min to obtain polyethylene glycol silicon dioxide mixed solution;
2) According to the weight parts, 160 parts of formaldehyde is added into a three-neck flask provided with a stirrer and a thermometer, 30% sodium hydroxide is used for adjusting the pH value to 9-10, 1 part of polyvinyl alcohol, 70 parts of melamine and 46 parts of urea are sequentially added, the temperature is raised to 40 ℃, the polyethylene glycol and silicon dioxide mixed solution obtained in the step 1) is added, the temperature is raised to 78 ℃, the pH value is kept at 8.7, the temperature is kept for a period of time, the reaction end point is determined by adopting a turbidity experimental method, and if the temperature reaches the requirement, the temperature is rapidly reduced, so that the light yellow melamine resin solution is obtained.
Example 4: the preparation method of the nano silica modified melamine formaldehyde resin of embodiment 4 comprises the following steps:
1) Preparing 5% aqueous solution of nano silicon dioxide according to parts by weight, slowly putting 1.6 parts of nano silicon dioxide into a three-neck flask provided with a stirrer and a thermometer, and then putting 20 parts of polyethylene glycol and mixing for 10min to obtain polyethylene glycol silicon dioxide mixed solution;
2) According to parts by weight, 160 parts of formaldehyde is added into a three-neck flask provided with a stirrer and a thermometer, 30% sodium hydroxide is used for adjusting the pH value to 9-10, 1 part of polyvinyl alcohol, 70 parts of melamine and 46 parts of urea are sequentially added, the temperature is raised to 40 ℃, the polyethylene glycol and silicon dioxide mixed solution obtained in the step 1) is added, the temperature is raised to 78 ℃, the pH value is kept at 9, the temperature is kept for a period of time, the reaction endpoint is determined by adopting a turbid experimental method, and if the requirement is met, the temperature is rapidly reduced, so that the light yellow melamine resin solution is obtained.
Example 5: the preparation method of the nano silica modified melamine formaldehyde resin of embodiment 5 comprises the following steps:
1) Preparing 5% aqueous solution of nano silicon dioxide according to parts by weight, slowly putting 2 parts of the aqueous solution into a three-neck flask provided with a stirrer and a thermometer, and then putting 20 parts of polyethylene glycol and mixing for 10min to obtain polyethylene glycol-silicon dioxide mixed solution;
2) According to the weight parts, 160 parts of formaldehyde is added into a three-neck flask provided with a stirrer and a thermometer, 30% sodium hydroxide is used for adjusting the pH value to 9-10, 1 part of polyvinyl alcohol, 70 parts of melamine and 46 parts of urea are sequentially added, the temperature is raised to 40 ℃, the polyethylene glycol and silicon dioxide mixed solution obtained in the step 1) is added, the temperature is raised to 78 ℃, the pH value is kept at 9.5, the temperature is kept for a period of time, the reaction end point is determined by adopting a turbidity experimental method, and if the temperature reaches the requirement, the temperature is rapidly reduced, so that the light yellow melamine resin solution is obtained.
Referring to FIG. 1, the relationship between the amount of the added nano-silica obtained in examples 1-5 and the free formaldehyde content of the melamine resin is shown, and FIG. 2 is the relationship between the amount of the added nano-silica obtained in examples 1-5 and the elongation at break of the melamine resin is shown as follows:
referring to fig. 3, examples 2-4 give a graphical representation of the Tg curves of the melamine resin for different nanosilica loadings, and the decrease in glass transition temperature is shown in fig. 3.
The embodiments of the present invention have been described in order to explain the present invention rather than to limit the scope of the claims, and it is intended that all such modifications and variations that fall within the true spirit and scope of the invention are possible and within the scope of the invention.
Claims (1)
1. A preparation method of nano silicon dioxide modified melamine formaldehyde resin is characterized by comprising the following steps:
1) Preparing 5% aqueous solution of nano silicon dioxide according to parts by weight, mixing 1-2 parts of nano silicon dioxide with 20 parts of polyethylene glycol, and obtaining a mixture A after 10 min;
2) According to the weight parts, 160 parts of formaldehyde is adjusted to pH 9-10 by 30% sodium hydroxide, 1 part of polyethylene glycol, 70 parts of melamine and 46 parts of urea are sequentially added, the temperature is raised to 40 ℃, the mixture A in the step 1) is added, the temperature is continuously raised to 75-80 ℃, the pH value is kept at more than 8.5-9.5, the temperature is kept at the constant temperature of 75-80 ℃ for 2.5-3.5h, the clouding point is sampled and monitored under the constant temperature state of 75-80 ℃, when the clouding point is reached, the temperature is lowered to 40 ℃, and the pH value is adjusted to 9-10 by 30% sodium hydroxide, so that the nano silicon dioxide modified melamine formaldehyde resin is obtained.
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| CN114644808B (en) * | 2020-12-21 | 2024-03-08 | 大连理工江苏研究院有限公司 | Modified melamine formaldehyde resin composite material and preparation method thereof |
| CN113389082B (en) * | 2021-07-19 | 2023-02-10 | 广东福美新材料科技有限公司 | Long-acting low-formaldehyde impregnated paper and preparation method thereof |
| CN113773717A (en) * | 2021-09-24 | 2021-12-10 | 湖南同进装饰材料有限公司 | Resin decorative plate for building engineering and manufacturing method thereof |
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| CN101880437A (en) * | 2009-05-05 | 2010-11-10 | 江门市双键化学企业有限公司 | Method for preparing nano modified urea resin |
| CN101585953B (en) * | 2009-06-23 | 2010-12-29 | 中国林业科学研究院林产化学工业研究所 | Method for preparing melamine formaldehyde molding compound |
| CN102120809B (en) * | 2011-04-26 | 2012-09-26 | 福建农林大学 | Nano aluminum oxide modified tripolycyanamide formaldehyde wear-resistant resin and preparation method thereof |
| CN102219885A (en) * | 2011-04-26 | 2011-10-19 | 福建农林大学 | Nano silicon oxide modified melamine formaldehyde resin and preparation method thereof |
| CN105273359B (en) * | 2015-09-11 | 2018-01-23 | 苏州兴业材料科技股份有限公司 | High silica containing Mo-phenolic resin of carbon residue and preparation method thereof |
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