CN-121989333-A - Method for improving temperature resistance and surface hydrophobicity of bamboo wood

Abstract

The invention relates to the technical field of bamboo processing and food packaging, and in particular discloses a scheme for improving the temperature tolerance and surface hydrophobicity of bamboo, which comprises the following steps of preprocessing, and adopting ultrasonic-assisted hydrothermal treatment of raw materials; and (3) coating the bamboo material surface with the coating, wherein the coating comprises Cellulose Nanofiber (CNF), food-grade high-hardness resin and food-grade silicon dioxide, and the bamboo material capable of resisting high temperature of 200 ℃ and being repeatedly used for food contact can be prepared after solidification. The method effectively removes heat-sensitive substances in the bamboo by mild and repeated ultrasonic pretreatment, eliminates soluble sugar with strong hygroscopicity on the surface of the bamboo, improves the heat resistance of the bamboo on the premise of not damaging mechanical properties, adopts a biomass-based temperature-resistant coating, has strong coating adhesion, and forms a layer of compact physical barrier on the surface of the bamboo by food-grade high-hardness resin to prevent moisture penetration. CNF is used as a nano reinforcing phase, and the strength, toughness and adhesive force to bamboo materials of the coating are improved through a three-dimensional network structure. In addition, the food-grade silicon dioxide is dispersed in the coating to form a micro-coarse structure for blocking air, so that the hydrophobic effect is further enhanced, the product has hydrophobicity on the premise of improving the temperature resistance of the product, is safe and nontoxic, and meets the safety standard of food contact materials. The bamboo material is suitable for application scenes such as food processing devices, catering kitchen ware, cooking and the like.

Inventors

• ZENG JINSONG
• ZHANG XIN
• GONG ZHIQIANG

Assignees

• 广东松恒科技有限公司
• 华南理工大学

Dates

Publication Date

20260508

Application Date

20260306

Claims (9)

1. 1. The method for improving the temperature resistance and the surface hydrophobicity of the bamboo is characterized by comprising the following steps of: s1, carrying out ultrasonic pretreatment on bamboo chips, namely carrying out ultrasonic treatment on the bamboo chips in water at 25-100 ℃ for 10-50min each time, and repeating for 5-10 times; S2, compounding the high-temperature-resistant food-grade coating, namely uniformly mixing and stirring CNF with a certain concentration with resin and silicon dioxide; and S3, coating and curing the coating obtained in the step S2 on the surface of the bamboo chip pretreated in the step S1, and then curing.
2. 2. The method according to claim 1, wherein the ultrasonic pretreatment frequency in step S1 is 20-100kHz and the power is 100-500W, the bamboo chips are taken out and replaced with fresh deionized water at each treatment interval, and the bamboo chips are air-dried overnight after the treatment.
3. 3. The preparation method according to claim 1, wherein the concentration of cellulose CNF in step S2 can be adjusted by ethanol.
4. 4. The method according to claim 1, wherein the resin in step S2 is a food-grade high-hardness resin and has a temperature resistance, preferably an epoxy silicone resin.
5. 5. The method of claim 1, wherein the silica in step S2 is food grade silica or hydrophobic fumed silica, preferably an inorganic filler such as boron nitride or titanium dioxide.
6. 6. The preparation method of claim 1, wherein the absolute dry mass ratio of each component in the step S2 is that the resin CNF and the silicon dioxide are 5-10:1:1-5, and the mixing and stirring time of the three components is not less than 30min.
7. 7. The method according to claim 1, wherein the coating method in the step S3 is spray coating, dip coating, brush coating or knife coating, the coating amount is 20-130g/m 2 , and the curing process is 25-75 ℃ for 10-60 min.
8. 8. A method for improving the temperature resistance and the surface hydrophobicity of bamboo materials, which is characterized in that the bamboo materials are prepared by the method of any one of claims 1-7, the bamboo materials are subjected to ultrasonic hydrothermal pretreatment, the high temperature resistance of the bamboo materials is improved, and the food-grade hydrophobic temperature-resistant coating is used for assisting, so that the high temperature resistance, the food contact safety and the reusability of the bamboo materials are realized.
9. 9. The bamboo material of claim 8, which is used in food contact appliances, molds, cooking trays and kitchen ware.

Description

Method for improving temperature resistance and surface hydrophobicity of bamboo wood Technical Field The invention belongs to the technical fields of bamboo processing modification, food contact materials and high-temperature-resistant coatings, and relates to a method for improving the temperature resistance and surface hydrophobicity of bamboo. Background The bamboo has high growth speed, can be regenerated, has excellent mechanical properties, is an ideal environment-friendly material, can be used for food appliances and food products, and is natural and attractive in appearance and is deeply favored by consumers. However, natural bamboo contains lignin, hemicellulose and heat-sensitive components, and is easy to oxidize and blacken in a high-temperature environment, so that the appearance and the service life are seriously influenced. In the prior art, bleaching or chemical agents are adopted for treatment, so that on one hand, the strength of bamboo wood can be reduced, and on the other hand, the residual chemical agents can bring potential food safety hazards and are poor in heat resistance. There is a lack of integration solutions that compromise high temperature resistance, hydrophobicity, food-grade and reusability. If the bamboo is not preprocessed, the bamboo is directly used for processing finished products, and when the natural bamboo chips are subjected to high temperature, the surfaces of the natural bamboo chips are rapidly yellowing and even blackish brown spots appear, so that the technical scheme can remove extractives such as sugar and starch rich in the bamboo by carrying out ultrasonic auxiliary hydrothermal treatment on the bamboo, and the temperature resistance of the bamboo can be improved. In addition, in order to further improve the durability of the bamboo product, a protective layer is often coated on the surface of the bamboo product, but most of the commercially available coatings are common varnish, paraffin coatings, polyethylene coatings, acrylic resin coatings, polylactic acid coatings, polytetrafluoroethylene coatings and the like, and the coating has various defects, such as low melting point of the paraffin coatings, limited strength performance, insufficient temperature resistance of the polylactic acid coatings, easy falling off after long-term use, and partial coating materials not meeting the requirements of food contact grade. Therefore, the preparation method of the food-grade hydrophobic coating which can fundamentally inhibit the high-temperature blackening of the bamboo chips and endow the bamboo chips with high-temperature resistance is developed, and has important practical value and market prospect. With the increasing depth of environmental protection concepts, CNF is taken as a biological-based nanomaterial derived from natural plants, and is introduced into a coating preparation system, so that the CNF has the remarkable advantages of being renewable and degradable and the like. Various methods for preparing CNF have been developed so far, and the prepared CNF is a long filiform network structure with a nano-scale diameter and an extremely high aspect ratio. The viscosity of the CNF is regulated by ethanol, so that the tensile strength and toughness of the coating can be obviously improved, nanoscale uniform dispersion can be realized in the resin, excessive association of hydrogen bonds between CNFs can be effectively inhibited, a coating mixed system keeps proper viscosity and fluidity, the target thickness can be achieved by single coating of the coating, the coating times are reduced, and the industrial production is facilitated. Aiming at the defects that the bamboo is not high-temperature resistant, the existing coating is poor in temperature resistance, can not be used in the field of food and the like, the invention provides a brand new solution from the pretreatment of the bamboo and the compounding of the high-temperature-resistant food-grade super-hydrophobic coating, and aims to solve the technical problems of the bamboo in the field of food application. Disclosure of Invention In order to solve the problems that the existing bamboo tableware is easy to turn black, poor in durability, incapable of being reused and the like in a high-temperature environment, the invention provides a method for improving the thermal stability of bamboo chips through ultrasonic pretreatment, and combines a high-temperature-resistant food-grade hydrophobic coating to prepare the reusable 200-DEG C-high-temperature-resistant food-grade hydrophobic bamboo, thereby solving the problem that the existing food-grade coating is difficult to achieve both temperature resistance and hydrophobicity. In order to achieve the above purpose, the present invention adopts the following technical scheme: The invention provides a method for improving the temperature resistance and the surface hydrophobicity of bamboo wood, which comprises the following steps: Firstly, placing bambo