阅读说明：本技术 一种稻壳粉的改性方法、改性稻壳粉和复合材料 (Modification method of rice hull powder, modified rice hull powder and composite material ) 是由 刘海林 崔巍 赵原 刘和文 于 2020-05-07 设计创作，主要内容包括：本发明公开了一种稻壳粉的改性方法、改性稻壳粉和复合材料,稻壳粉的改性方法包括下述步骤：S1、制备纳米银改性稻壳粉；S2、制备聚多巴胺-纳米银包覆稻壳粉；S3、用改性环氧乳液对所述聚多巴胺-纳米银包覆稻壳粉进行改性处理,得到改性稻壳粉。本发明的改性稻壳粉与密胺树脂共混制成的复合材料既具有优良的疏水性能和抗菌性能,又具备良好的机械性能,其外观质量高,卫生性好,耐用性强,适合广泛应用于餐具制造领域。(The invention discloses a rice hull powder modification method, modified rice hull powder and a composite material, wherein the rice hull powder modification method comprises the following steps: s1, preparing nano-silver modified rice hull powder; s2, preparing polydopamine-nano silver coated rice hull powder; s3, modifying the polydopamine-nano silver coated rice hull powder by using a modified epoxy emulsion to obtain modified rice hull powder. The composite material prepared by blending the modified rice hull powder and the melamine resin has excellent hydrophobic property and antibacterial property, good mechanical property, high appearance quality, good sanitation and strong durability, and is suitable for being widely applied to the field of tableware manufacturing.)

1. A method for modifying rice hull powder is characterized by comprising the following steps:

s1, preparing nano-silver modified rice hull powder;

s2, preparing polydopamine-nano silver coated rice hull powder;

s3, modifying the polydopamine-nano silver coated rice hull powder by using a modified epoxy emulsion to obtain modified rice hull powder.

2. A method for modifying rice hull powder according to claim 1, comprising the steps of:

s1, adding the rice hull powder into a silver nitrate solution, uniformly mixing, then slowly dropwise adding an ascorbic acid solution, stirring for reaction, filtering, washing and drying to obtain nano-silver modified rice hull powder;

s2, dipping the nano-silver modified rice hull powder obtained in the step S1 in a dopamine hydrochloride solution, washing and drying to obtain poly-dopamine-nano-silver coated rice hull powder;

s3, uniformly spraying the modified epoxy emulsion into the polydopamine-nano silver coated rice hull powder, and drying to obtain the modified rice hull powder, wherein the modified epoxy emulsion is obtained by mixing water-based epoxy emulsion, nano silicon dioxide and nano titanium dioxide.

3. A method for modifying rice hull powder according to claim 2, characterized in that the weight ratio of said rice hull powder to silver nitrate solution is (0.05-0.1): 1, the concentration of the silver nitrate solution is 1.5-2.5mmol/L, the concentration of the ascorbic acid solution is 10-15mmol/L, and the volume ratio of the silver nitrate solution to the ascorbic acid solution is (0.8-1.2): 1.

4. a method for modifying rice hull powder according to claim 2 or 3, wherein in said step S1, the reaction temperature is 25-45 ℃ and the reaction time is 6-12 hours.

5. A method for modifying rice hull powder according to any of claims 2-4, characterized in that said dopamine hydrochloride solution has a concentration of 2-5g/L, and the weight ratio of said nano-silver modified rice hull powder to dopamine hydrochloride solution is (0.1-0.2): 1.

6. a method for modifying rice hull powder according to any of claims 2 to 5, wherein in said step S2, the temperature of the impregnation treatment is 25 to 30 ℃ and the time is 12 to 24 hours.

7. A method of modifying rice hull powder according to any of claims 2-6, characterized in that the weight ratio of said modified epoxy emulsion to poly-dopamine-nanosilver coated rice hull powder is (0.05-0.1): 1, in the modified epoxy emulsion, the weight ratio of the water-based epoxy emulsion to the nano silicon dioxide to the nano titanium dioxide is 1: (0.01-0.02): (0.01-0.03), the solid content of the aqueous epoxy emulsion is 10-30%, the particle size of the nano-silica is 100-200nm, and the particle size of the nano-titania is 30-50 nm.

8. A modified rice husk powder characterized by being obtained by the method for modifying rice husk powder according to any one of claims 1 to 7.

9. The composite material containing the modified rice hull powder is characterized by comprising the following raw materials in parts by weight:

70-90 parts of melamine formaldehyde resin, 70-90 parts of the modified rice hull powder as claimed in claim 8, 0.1-1 part of curing agent and 0-2 parts of auxiliary agent.

10. A method for preparing a composite material containing modified rice husk powder according to claim 9, comprising the steps of:

s1, weighing the raw materials according to the weight, mixing and stirring the melamine formaldehyde resin, the modified rice hull powder and the auxiliary agent uniformly, and then drying until the water content is less than or equal to 10%;

s2, mixing the material obtained in the step S1 with a curing agent, and then ball-milling for 6-10h to obtain the material.

Technical Field

The invention relates to the technical field of composite materials, in particular to a rice hull powder modification method, modified rice hull powder and a composite material.

Background

With more and more attention paid to ecological environment, the degradability and recyclability of materials become the key points of attention of people. The rice hull powder as a natural lignocellulose material has the advantages of light weight, high strength, degradability, environmental friendliness and the like, is a recyclable natural green material, and is widely applied to the manufacture of green environment-friendly tableware. These tableware are usually made by mixing rice hull powder as a filler with a raw material such as resin and molding. However, the rice hull powder has hydrophilicity and high water absorption rate, is easy to absorb water in the air to cause deformation and cracking, influences the durability of tableware, is also affected with damp to cause bacterial breeding, and seriously influences the sanitary performance of the tableware. Therefore, it is an important research topic to improve the hydrophobicity and antibacterial property of rice hull powder and keep the excellent mechanical property.

Disclosure of Invention

Based on the technical problems in the background art, the invention provides a rice hull powder modification method, modified rice hull powder and a composite material.

The invention provides a method for modifying rice hull powder, which comprises the following steps:

s1, preparing nano-silver modified rice hull powder;

s2, preparing polydopamine-nano silver coated rice hull powder;

s3, modifying the polydopamine-nano silver coated rice hull powder by using a modified epoxy emulsion to obtain modified rice hull powder.

Preferably, the method for modifying rice hull powder comprises the following steps:

s1, adding the rice hull powder into a silver nitrate solution, uniformly mixing, then slowly dropwise adding an ascorbic acid solution, stirring for reaction, filtering, washing and drying to obtain nano-silver modified rice hull powder;

s2, dipping the nano-silver modified rice hull powder obtained in the step S1 in a dopamine hydrochloride solution, washing and drying to obtain poly-dopamine-nano-silver coated rice hull powder;

s3, uniformly spraying the modified epoxy emulsion into the polydopamine-nano silver coated rice hull powder, and drying to obtain the modified rice hull powder, wherein the modified epoxy emulsion is obtained by mixing water-based epoxy emulsion, nano silicon dioxide and nano titanium dioxide.

Preferably, the weight ratio of the rice hull powder to the silver nitrate solution is (0.05-0.1): 1, the concentration of the silver nitrate solution is 1.5-2.5mmol/L, the concentration of the ascorbic acid solution is 10-15mmol/L, and the volume ratio of the silver nitrate solution to the ascorbic acid solution is (0.8-1.2): 1.

preferably, in the step S1, the reaction temperature is 25-45 ℃ and the reaction time is 6-12 h.

Preferably, the concentration of the dopamine hydrochloride solution is 2-5g/L, and the dopamine hydrochloride solution is preferably prepared by dissolving dopamine hydrochloride in a Tris-HCl solution with the pH of 8.5.

Preferably, the weight ratio of the nano-silver modified rice hull powder to the dopamine hydrochloride solution is (0.1-0.2): 1.

preferably, in the step S2, the temperature of the dipping treatment is 25-30 ℃ and the time is 12-24 h.

Preferably, the weight ratio of the modified epoxy emulsion to the polydopamine-nano silver coated rice hull powder is (0.05-0.1): 1, in the modified epoxy emulsion, the weight ratio of the water-based epoxy emulsion to the nano silicon dioxide to the nano titanium dioxide is 1: (0.01-0.02): (0.01-0.03), the solid content of the aqueous epoxy emulsion is 10-30%, the particle size of the nano-silica is 100-200nm, and the particle size of the nano-titania is 30-50 nm.

A modified rice hull powder is prepared by the modification method of the rice hull powder.

A composite material containing modified rice hull powder comprises the following raw materials in parts by weight:

70-90 parts of melamine formaldehyde resin, 70-90 parts of modified rice hull powder, 0.1-1 part of curing agent and 0-2 parts of auxiliary agent.

A preparation method of a composite material containing modified rice hull powder comprises the following steps:

s1, weighing the raw materials according to the weight, mixing and stirring the melamine formaldehyde resin, the modified rice hull powder and the auxiliary agent uniformly, and then drying until the water content is less than or equal to 10%;

s2, mixing the material obtained in the step S1 with a curing agent, and then ball-milling for 6-10h to obtain the material.

Preferably, the curing agent is ethanolamine sulfate.

Preferably, the auxiliary agent comprises the following raw materials in parts by weight: 0.2-0.5 part of antioxidant, 0.2-0.5 part of coupling agent and 0.2-1 part of colorant.

Preferably, the antioxidant is one or a mixture of several of antioxidant 168, antioxidant 1076 and antioxidant DLTP; the coupling agent is one or a mixture of more of silane coupling agents KH550, KH560 and KH 570.

Preferably, the preparation method of the melamine formaldehyde resin comprises the following steps:

adding 100-120 parts by weight of formaldehyde solution with the concentration of 37% into a reactor, adjusting the pH to 9.3-9.5 by using NaOH solution, then heating to 35 ℃, stirring for 0.5-1h until the pH is stable, and then adding 30-40 parts by weight of melamine to react for 2-3h at 90-95 ℃ to obtain the melamine formaldehyde-formaldehyde resin.

The invention has the following beneficial effects:

the method comprises the steps of firstly using silver nitrate as a precursor, using ascorbic acid as a reducing agent, preparing rice hull powder with nano-silver loaded on the surface by an in-situ reduction method, then soaking the rice hull powder in a dopamine hydrochloride solution, forming a poly-dopamine crosslinking layer on the surface of the rice hull powder by utilizing the self-polymerization-crosslinking reaction of dopamine in water to obtain poly-dopamine-nano-silver coated rice hull powder, finally spraying aqueous epoxy emulsion modified by nano-silica and nano-titanium dioxide on the surface of the poly-dopamine-nano-silver coated rice hull powder, and utilizing the affinity of the poly-dopamine to epoxy resin to firmly attach the epoxy resin to the surface of the poly-dopamine-nano-silver coated rice hull powder to form a nano-silica-nano-titanium dioxide-epoxy composite layer. According to the modification method, on one hand, composite layers formed by nano silicon dioxide, nano titanium dioxide and epoxy resin with different particle sizes have certain roughness and water resistance, and the nano silver coating layer is combined, so that the coating layer on the surface of the rice hull powder has good density and certain roughness, a better hydrophobic effect is achieved, and the water resistance of the modified rice hull powder is greatly improved. The modified rice hull powder prepared by the invention is used as a filler, has excellent antibacterial property and water resistance, can introduce an epoxy group on the surface, greatly improves the compatibility with melamine resin, and a composite material prepared by blending the modified rice hull powder with the melamine resin has excellent hydrophobic property and antibacterial property, has good mechanical property, high appearance quality, good sanitation and strong durability, and is suitable for being widely applied to the field of tableware manufacturing.

Detailed Description

The technical solution of the present invention will be described in detail below with reference to specific examples.