CN114670301B

CN114670301B - Bamboo material with mildew-proof performance and modification method thereof

Info

Publication number: CN114670301B
Application number: CN202210264947.8A
Authority: CN
Inventors: 章伟伟; 孙杰宇; 胡传双; 林秀仪
Original assignee: South China Agricultural University
Current assignee: South China Agricultural University
Priority date: 2022-03-17
Filing date: 2022-03-17
Publication date: 2023-04-18
Anticipated expiration: 2042-03-17
Also published as: CN114670301A

Abstract

The invention belongs to the technical field of bamboo modification, and discloses bamboo with mildew resistance and a modification method thereof, wherein the bamboo with mildew resistance is obtained by soaking bamboo in a modification solution prepared from an acrylamide derivative monomer and a catalyst, so that the acrylamide derivative monomer permeates into the bamboo; in-situ polymerization reaction at 60-90 deg.c and heat treatment at 105-140 deg.c. The bamboo material with the mildew-proof performance of the invention keeps the appearance color and texture of the bamboo material, does not release pungent smell, and has good mildew-proof performance. The method has the advantages of low concentration of the required modified solution and mild reaction conditions, can solve the mildew problem of wood and bamboo in the storage, transportation and use processes, overcomes the defect of economic loss caused by the reduction of the mildew quality of bamboo, and has wide application prospect.

Description

Bamboo material with mildew-proof performance and modification method thereof

Technical Field

The invention belongs to the technical field of bamboo modification, and particularly relates to a bamboo with mildew resistance and a modification method thereof.

Background

The bamboo has the advantages of reproducibility, high wood forming speed, high strength, high yield, easiness in processing and the like, and is widely applied to the fields of buildings, papermaking, textiles, furniture and the like. However, the bamboo has high content of starch, protein, sugar and fat, and objectively provides nutrients for growth and propagation of mold, so that the bamboo is easy to mildew in the processes of processing, transportation, use and the like. The mildew of the bamboo wood damages the appearance color and the natural texture of the bamboo wood and various bamboo products, and seriously influences the use value and the economic value of the bamboo wood and various bamboo products. Therefore, the mildew-proof treatment of the bamboo wood has important significance for the industrial development of the bamboo wood.

Patent CN104552516A discloses a preparation method of furfuryl alcohol resin modified solution for wood or bamboo, wherein the modified solution contains 15-70% of furfuryl alcohol, 1-3% of borax, 1.5-2.0% of a catalyst prepared by compounding citric acid and oxalic acid and water. Furfuryl alcohol resin modification of different degrees is carried out on the wood or the bamboo in a brushing, soaking or pressurizing and dipping mode, so that the dimensional stability, the mildew resistance and partial mechanical properties of the wood and the bamboo are improved. The technology has the defects that the furfuryl alcohol used in the modification process is high in concentration and has pungent smell, and the color of a treated sample is deepened, so that the original color and texture of bamboo wood are lost.

Patent CN109333718A discloses a mildew-proof treatment method for bamboo wood, which comprises preparing copper-containing compound impregnation liquid from copper hydroxide, diethanolamine, polyethylene glycol and water according to a mass ratio of 1. According to the invention, the nano-copper in-situ polymerization and heat treatment technology are combined, so that the moisture absorption performance of the bamboo is effectively reduced, the nano-copper can inhibit the growth of mould, and the control efficiency of the obtained modified bamboo can reach more than 90%. The technology has the defects that the dosage of a modifying reagent is large, the heat treatment temperature is high, the modified bamboo wood obtained under the catalysis of copper is dark in color, and the original color and texture of the bamboo wood are lost.

Disclosure of Invention

In order to solve the defects of the prior art, the invention mainly aims to provide the bamboo material with the mildew-proof performance. The bamboo material has the original appearance color and luster maintained, does not release pungent smell, and has good mildew resistance.

The invention also aims to provide a method for modifying the bamboo material with the mildew-proof performance. The method adopts a dipping-in-situ polymerization-heat treatment method to prepare the modified bamboo wood, and has the advantages of low concentration, high efficiency, no color, no odor, greenness and environmental protection.

The purpose of the invention is realized by the following technical scheme:

the bamboo material with the mildew resistance is prepared by soaking the bamboo material in a modified solution prepared from an acrylamide derivative monomer and a catalyst, so that the acrylamide derivative monomer permeates into the bamboo material; in-situ polymerization reaction at 60-90 deg.c and heat treatment at 105-140 deg.c.

Preferably, the bamboo material is more than one of moso bamboo, early bamboo, lophatherum gracile, green bamboo and arrowhead bamboo.

Preferably, the acrylamide derivative monomer in the modification solution is one or a mixture of any two of N-hydroxymethyl acrylamide and N-hydroxymethyl methacrylamide; the mass concentration of the acrylamide derivative monomer in the modification solution is 2-20%;

preferably, the catalyst is ammonium persulfate, hydrogen peroxide or azobisisobutyramidine hydrochloride (V-50 initiator); the addition amount of the catalyst is 0.1-5% of the mass of the acrylamide derivative monomer.

Preferably, the impregnation mode is vacuum pressure impregnation or normal pressure impregnation.

More preferably, the time of the normal pressure impregnation is 12 to 48 hours; the vacuum pressure impregnation conditions comprise that the vacuum degree is 0.08-0.1 MPa, the pressure is 0.5-1.5 MPa, and the impregnation time is 2-8 h.

Preferably, the time of the polymerization reaction is 1 to 12 hours; the time of the heat treatment is 1 to 10 hours.

The modification method of the bamboo wood with the mildew-proof performance comprises the following specific steps:

s1, soaking bamboo wood in a modified solution prepared from an acrylamide derivative monomer and a catalyst to prepare soaked bamboo wood;

s2, carrying out in-situ polymerization reaction on the impregnated bamboo wood at the temperature of 60-90 ℃ to prepare polymerized bamboo wood;

s3, carrying out heat treatment on the polymerized bamboo at 105-140 ℃ to enable the polymer to have a cross-linking reaction, so as to obtain the bamboo with the mildew-proof performance.

The modified solution selected by the invention contains a monomer with double functional groups, and unsaturated double bonds and hydroxymethyl are contained in molecules. At 60-90 deg.c, the catalyst can initiate unsaturated double bond to produce polymerization reaction and the heat treatment can initiate hydroxymethyl to produce cross-linking reaction. The modified monomer after being dipped enters the bamboo cell cavity to generate in-situ polymerization-crosslinking reaction, and a film is formed on the surface of the starch particle nutrient source to form a protective barrier, so that the mould mycelia are prevented from utilizing the nutrient sources such as starch and the like, and the growth and the propagation of the mould are inhibited, thereby achieving the mould proof effect. The selected modifier is a neutral reagent, so that the bamboo is not subjected to acid degradation or alkali degradation, and the appearance color of the bamboo is not changed.

Compared with the prior art, the invention has the following beneficial effects:

1. the bamboo prepared by the invention has good and stable mildew resistance, has no obvious change in appearance and color before and after treatment, does not release irritant gas, increases the utilization possibility of the bamboo in different scenes, solves the mildew problem of the bamboo in the storage, transportation and use processes, improves the defect of economic loss caused by the reduction of the mildew quality of the bamboo, and has wide application prospect.

2. The water-soluble acrylamide derivative selected by the invention is an environment-friendly reagent, and the modified bamboo wood can achieve a good mildew-proof effect when the mass concentration of the acrylamide derivative reaches more than 6%.

3. The invention takes bamboo as a matrix, adopts the process of dipping-in-situ polymerization/heat treatment, has simple and easy operation of the preparation method, low concentration of the required modified solution, mild reaction condition, low requirements on equipment and treatment condition and low cost.

Drawings

FIG. 1 is a photograph comparing an unmodified bamboo material (a) with a modified bamboo material (b) obtained in examples 1 to 4.

FIG. 2 is a comparison photograph of unmodified bamboo before and after mildew resistance test.

FIG. 3 is a photograph showing the modified bamboo materials obtained in examples 1 to 4 before and after the mildew-proof test.

Fig. 4 is an electron micrograph of the unmodified bamboo (a) and the modified bamboo (b) of example 4.

Detailed Description

The following examples are presented to further illustrate the invention and should not be construed as limiting the invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. Reagents, methods and apparatus used in the present invention are conventional in the art unless otherwise indicated.

Example 1

1. Preparation: (1) Baking a moso bamboo sample (50mm × 20mm × 5mm) to an absolutely dry state (namely, completely removing free water and bound water in bamboo materials) to obtain an absolutely dry moso bamboo sample, and sealing for later use;

(2) 500mL of 2% N-methylolacrylamide aqueous solution is prepared, ammonium persulfate is added as a catalyst (the mass of the ammonium persulfate is 1% of that of the added N-methylolacrylamide), and the mixture is stirred to obtain a clear and transparent modified solution.

(3) Completely soaking the completely dried moso bamboo sample in the modified solution, carrying out vacuum treatment for 1h, pressurizing to 0.8MPa, and maintaining the pressure for 3h. And (5) continuing soaking for 8 hours under normal pressure after pressure relief. Taking out, placing in an oven, and polymerizing for 12h at 80 ℃; drying at 105 ℃ to be absolutely dry after polymerization to obtain the modified bamboo wood, namely the bamboo wood with mildew-proof performance.

2. And (3) mildew resistance test: in testing the mildew resistance of bamboo materials according to ASTM D3273-16, the bacterial suspension was sprayed on the surface of bamboo materials, incubated at 28 ℃ and 80% RH for 4 weeks, and the control efficiency was defined according to the infected area on the surface of wood. (0 means no hyphae on the surface, 1 means surface infected area <1/4,2 means surface infected area between 1/4 and 1/2,3 means surface infected area between 1/2 and 3/4,4 means surface infected area > 3/4). The mildew-proof efficacy of the bamboo wood with mildew-proof performance obtained in the embodiment is 4, which shows that the mildew-proof effect of the modified bamboo wood is not obvious when the mass concentration of the N-hydroxymethyl acrylamide aqueous solution is 2%.

Example 2

1. Preparation: (1) Drying a mao bamboo sample (50mm: 20mm: 5mm) to be in an absolute dry state (namely, free water and combined water in bamboo are completely removed), preparing an absolute dry mao bamboo sample, and sealing for later use;

(2) 500mL of N-hydroxymethyl acrylamide aqueous solution with the mass concentration of 4% is prepared, ammonium persulfate is added as a catalyst (the mass of the ammonium persulfate is 1% of the mass of the added N-hydroxymethyl acrylamide), and the mixture is stirred to obtain a clear and transparent modified solution.

(3) Completely soaking the completely dried moso bamboo sample in the modified solution, carrying out vacuum treatment for 1h, pressurizing to 0.8MPa, and maintaining the pressure for 3h. After pressure relief, continuously soaking for 8h under normal pressure, placing in an oven, and polymerizing for 8h at 80 ℃; drying at 105 ℃ to be absolutely dry after polymerization to obtain the modified bamboo wood, namely the bamboo wood with mildew-proof performance.

2. And (3) mildew resistance test: the mildew-proof efficacy of the bamboo wood with mildew-proof performance obtained in the embodiment is 2, and the testing method is the same as that of the embodiment 1). (the fact that the mildew resistance of the obtained modified bamboo wood is improved when the mass concentration of the N-hydroxymethyl acrylamide aqueous solution is 4% is shown.

Example 3

(2) 500mL of 6 mass percent N-methylolacrylamide aqueous solution is prepared, ammonium persulfate (the mass of the ammonium persulfate is 1 percent of the mass of the added N-methylolacrylamide) is added as a catalyst, and the mixture is stirred to obtain a clear and transparent modified solution.

(3) Completely soaking the absolutely dried moso bamboo sample in the modified solution for 2 days under normal pressure. Taking out a sample, putting the sample in an oven, and polymerizing for 12 hours at 65 ℃; drying at 105 ℃ to be absolutely dry after polymerization to obtain the modified bamboo wood, namely the bamboo wood with mildew-proof performance.

2. And (3) mildew resistance test: the mildew-proof efficacy of the bamboo material with mildew-proof performance obtained in the present example was 0 (the test method was the same as in example 1). The mildew resistance of the obtained modified bamboo wood is obviously improved when the mass concentration of the N-hydroxymethyl acrylamide aqueous solution is 6%.

Example 4

(2) 500mL of N-methylolacrylamide aqueous solution with the mass concentration of 8% is prepared, ammonium persulfate (the mass of the ammonium persulfate is 1% of the mass of the added N-methylolacrylamide) is added to serve as a catalyst, and the mixture is stirred to obtain a clear and transparent modified solution.

(3) Completely soaking the completely dried moso bamboo sample in the modified solution, carrying out vacuum treatment for 1h, pressurizing to 0.5MPa, and maintaining the pressure for 3h. After pressure relief, continuously soaking for 8h under normal pressure, placing in an oven, and polymerizing for 12h at 80 ℃; drying at 105 ℃ to be absolutely dry after polymerization to obtain the modified bamboo wood, namely the bamboo wood with mildew-proof performance.

2. And (3) mildew resistance test: the mildew-proof efficacy of the bamboo material having mildew-proof performance in this example was 0 (the test method was the same as in example 1). The mildew resistance of the obtained modified bamboo wood is obviously improved when the mass concentration of the N-hydroxymethyl acrylamide aqueous solution is 8%.

FIG. 1 is a photograph comparing an untreated bamboo (a) with a modified bamboo (b) obtained in examples 1 to 4. As can be seen from fig. 1, the color and appearance of the bamboo material subjected to the modification treatment are not obviously changed. FIG. 2 is a comparison photograph of unmodified bamboo before and after mildew resistance test. Wherein, (a) is a photo before the mildew-proof test of the unmodified bamboo wood; and (b) is a photo of the unmodified bamboo wood after four weeks of mildewproof test. As can be seen from FIG. 2, the surface of the unmodified bamboo material is completely covered by hyphae after the mold spores are inoculated according to the ASTM D3273-16 standard for four weeks, which shows that the mold-proof effect is poor. FIG. 3 is a photograph showing the modified bamboo material of examples 1-4 before and after the mildew resistance test. The modified bamboo material obtained in example 1 was (a), (b) and (c) used in example 2, and (d) used in example 4. As can be seen from FIG. 3, the antifungal effect gradually increased with the increase in the concentration of the aqueous N-methylolacrylamide solution. Fig. 4 is an electron micrograph of the unmodified bamboo (a) and the modified bamboo (b) of example 4. As can be seen from FIG. 4, the untreated bamboo wood cell cavities are rich in starch particles, and the starch particles in the modified bamboo wood cell cavities are still clearly visible.

Example 5

1. Preparation: (1) Drying the crude bamboo sample (50mm 0mm 5 mm) to the absolutely dry state (namely, free water and bound water in bamboo are completely removed) to obtain the absolutely dry crude bamboo sample, and sealing for later use;

(2) 500mL of N-hydroxymethyl acrylamide aqueous solution with the mass concentration of 10% is prepared, ammonium persulfate is added as a catalyst (the mass of the ammonium persulfate is 1% of the mass of the added N-hydroxymethyl acrylamide), and the mixture is stirred to obtain a clear and transparent modified solution.

(3) Completely soaking the completely dried moso bamboo sample in the modified solution, soaking for 2 days at normal pressure, placing in an oven, and polymerizing for 8h at 80 ℃; and performing heat treatment for 4 hours at 110 ℃ after polymerization to prepare the modified bamboo wood, namely the bamboo wood with the mildew-proof performance.

2. And (3) mildew resistance test: the mildew-proof efficacy of the bamboo material with mildew-proof performance obtained in the example is 0 (the testing method is the same as that of the example 1). The mildew resistance of the obtained modified bamboo wood is obviously improved when the mass concentration of the N-hydroxymethyl acrylamide aqueous solution is 10%.

Example 6

1. Preparation: (1) Drying the moso bamboo sample (50mm: 20mm: 5mm) with bamboo green and bamboo yellow removed to an absolute dry state (namely, free water and bound water in bamboo are completely removed), preparing an absolute dry moso bamboo sample, and sealing for later use;

(2) 500mL of 6 mass percent N-methylolacrylamide aqueous solution is prepared, ammonium persulfate is added as a catalyst (the mass of the ammonium persulfate is 1 percent of the mass of the added N-methylolacrylamide), and the mixture is stirred to obtain a clear and transparent modified solution.

(3) Completely soaking the completely dried moso bamboo sample in the modified solution, carrying out vacuum treatment for 1h, pressurizing to 0.8MPa, and maintaining the pressure for 3h. After pressure relief, continuously soaking for 8h under normal pressure, placing in an oven, and polymerizing for 8h at 80 ℃; and after polymerization, carrying out heat treatment at 120 ℃ for 4 hours to prepare the modified bamboo wood, namely the bamboo wood with the mildew-proof performance.

Example 7

(3) Completely soaking the completely dried moso bamboo sample in the modified solution, carrying out vacuum treatment for 1h, pressurizing to 0.8MPa, and maintaining the pressure for 3h. After the pressure is relieved, the soaking is continued for 8 hours under normal pressure. Taking out a sample, putting the sample in an oven, and polymerizing for 12 hours at 70 ℃; and (3) performing heat treatment for 2 hours at 130 ℃ after polymerization to obtain the modified bamboo wood, namely the bamboo wood with mildew-proof efficacy.

Example 8

(2) 500mL of N-hydroxymethyl methacrylamide aqueous solution with the mass concentration of 10% is prepared, ammonium persulfate is added as a catalyst (the mass of the ammonium persulfate is 1% of the mass of the added N-hydroxymethyl acrylamide), and the mixture is stirred to obtain a clear and transparent modified solution.

(3) Completely soaking the completely dried moso bamboo sample in the modified solution, carrying out vacuum treatment for 1h, pressurizing to 0.5MPa, and maintaining the pressure for 3h. And (5) continuing soaking for 8 hours under normal pressure after pressure relief. Taking out a sample, putting the sample in an oven, and polymerizing for 8 hours at 95 ℃; and (3) performing heat treatment for 2 hours at 140 ℃ after polymerization to obtain the modified bamboo wood, namely the bamboo wood with the mildew-proof performance.

2. And (3) mildew resistance test: the mildew-proof efficacy of the bamboo material with mildew-proof performance obtained in the present example was 0 (the test method was the same as in example 1). The mildew resistance of the obtained modified bamboo wood is obviously improved when the mass concentration of the N-hydroxymethyl acrylamide aqueous solution is 10%.

Example 9

(2) 500mL of N-hydroxymethyl methacrylamide aqueous solution with the mass concentration of 15% is prepared, ammonium persulfate is added as a catalyst (the mass of the ammonium persulfate is 1% of the mass of the added N-hydroxymethyl acrylamide), and the mixture is stirred to obtain a clear and transparent modified solution.

(3) Completely soaking the dried moso bamboo sample in the modified solution for 2 days under normal pressure. Taking out a sample, putting the sample in an oven, and polymerizing for 12 hours at 70 ℃; and after polymerization, performing heat treatment at 120 ℃ for 4 hours to prepare the modified bamboo wood, namely the bamboo wood with the mildew-proof performance.

2. And (3) mildew resistance test: the mildew-proof efficacy of the bamboo material with mildew-proof performance obtained in the example is 0 (the testing method is the same as that of the example 1). The mildew resistance of the obtained modified bamboo wood is obviously improved when the mass concentration of the N-hydroxymethyl acrylamide aqueous solution is 15%.

The above examples are suitable embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and they are included in the scope of the present invention.

Claims

1. A method for modifying bamboo wood with mildew resistance is characterized by comprising the following specific steps:

s1, soaking the oven-dried bamboo in a modified solution prepared from an acrylamide derivative monomer and a catalyst to enable the acrylamide derivative monomer to penetrate into the bamboo to obtain the soaked bamboo;

the acrylamide derivative monomer in the modified solution is one or a mixture of any two of N-hydroxymethyl acrylamide and N-hydroxymethyl methacrylamide; the mass concentration of the acrylamide derivative monomer in the modified solution is 6-15%; the catalyst is ammonium persulfate, hydrogen peroxide or azodiisobutyl amidine hydrochloride; the addition amount of the catalyst is 0.1-5% of the mass of the acrylamide derivative monomer; the impregnation mode is vacuum pressure impregnation or normal pressure impregnation; the time of the normal pressure impregnation is 12 to 48 hours; the vacuum pressure impregnation conditions comprise that the vacuum degree is 0.08-0.1 MPa, the pressure is 0.5-1.5 MPa, and the impregnation time is 2-8 h; the bamboo material is more than one of moso bamboo, early bamboo, henon bamboo, green bamboo and Sagittaria sagittifolia;

s2, carrying out in-situ polymerization reaction on the impregnated bamboo wood at the temperature of 65-90 ℃ for 8-12 h to prepare polymerized bamboo wood;

s3, carrying out heat treatment on the polymerized bamboo material at 105-140 ℃ for 2-4 h to enable the polymer to have a cross-linking reaction, thus obtaining the bamboo material with the mildew-proof performance.

2. A bamboo material having mold-proof properties, which is produced by the method of claim 1.