A method for preparing wood adhesive using shrimp and crab shells as all components

Abstract

The present invention provides a method for preparing wood adhesive using shrimp and crab shells as all components. The waste shrimp and crab shells are used as raw materials, and the components are depolymerized through ball milling, surface amination and other steps, and then solidified and cross-linked to prepare adhesive. The method not only fully utilizes fishery processing waste, but also improves the water-resistant bonding performance of the adhesive. The adhesive can be used to produce artificial boards such as particleboard, fiberboard, and plywood. The prepared artificial boards do not release free formaldehyde, have natural antibacterial and mildew-proof effects, can be widely used in furniture or decoration industries, and have broad application prospects.

Description

Technical Field

[0001] The invention belongs to the field of wood adhesives, and particularly relates to a method for preparing wood adhesives by utilizing shrimp and crab shells as all components. Background Art

[0002] The annual consumption of adhesives in China's wood processing industry exceeds 15 million tons, accounting for about two-thirds of the total adhesive production; among them, wood adhesives made from petrochemical products account for more than 80%. The main raw materials (formaldehyde, phenol) of this type of adhesive come from petroleum and have poor renewability; carcinogens (such as formaldehyde) are continuously emitted during the production and use process, which is harmful to human health; the product has poor degradability and is easy to pollute the environment. Therefore, research on wood adhesives made from renewable biomass, such as plant protein, carbohydrates, vegetable oil, lignin, tannin, etc., has attracted people's attention and achieved good results; but the antibacterial and mildew-proof effects of adhesives or boards are not good. Using chitosan extracted from crustaceans, such as shrimp and crab shells, as an adhesive raw material takes advantage of the fact that chitosan is insoluble in water or organic solvents but can be dissolved in acetic acid solution at low concentrations; Hang Su, Guanben Du et al. dissolved chitosan in acetic acid solution and applied it to the surface of bamboo after surface oxidation treatment, achieving a good bonding effect (Su H, Du G, Ren X, et al. High-performance bamboo composites based on the chemical bonding of active bamboo interface and chitosan[J]. International Journal of Biological Macromolecules, 2023: 125345.). However, the concentration of adhesives made from chitosan is generally less than 5%, and the volatilization of acetic acid during use will also produce odor and easily cause corrosion of metal equipment; at the same time, the process of extracting chitosan from shrimp and crab shells requires the use of a large amount of acid and alkali, which will also cause environmental pollution. Summary of the invention

[0003] The invention aims to provide a method for preparing a wood adhesive by utilizing shrimp and crab shells as all components.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for preparing a wood adhesive using shrimp and crab shells as all components, comprising the following steps:

[0006] (1) Wash the shrimp and crab shells, dry them at 103°C for 2 h, mechanically crush them into particles ≥ 60 mesh, and then obtain particles ≥ 3000 mesh by ball milling and ultrafine grinding for later use;

[0007] (2) mixing 50-80 parts by weight of shrimp and crab shell particles with 100-160 parts by weight of water, introducing carbon dioxide, stirring at 60 rpm for 60 min at 10° C., letting stand for 20 min, and filtering to separate the precipitate and the supernatant;

[0008] (3) The supernatant of step (2) is kept at 25-45°C for 10 minutes, and the precipitate and the supernatant are separated by filtration; carbon dioxide is introduced into the supernatant to partially replace the water in step (2), and the supernatant is continuously circulated between step (2) and step (3);

[0009] (4) mixing 10-50 parts by weight of the precipitate from step (2) with 20-100 parts by weight of an alkaline solution, keeping the mixture at 50-90° C. for 10-30 min, and filtering the mixture again to separate the precipitate and the supernatant;

[0010] (5) 20-40 parts by weight of the precipitate of step (4) and 20-40 parts by weight of a modifier are mixed and stirred at room temperature for 20 minutes, and then 30-90 parts by weight of the supernatant of step (4) and 10-20 parts by weight of the precipitate of step (3) are added to prepare a wood adhesive.

[0011] Further, the raw materials are as follows:

[0012] Shrimp and crab shell ingredients: shells of hairy crabs, swimming crabs, king crabs, lobsters, prawns and other shrimps and crabs.

[0013] Alkaline solution: one or more solutions of sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonia water, etc., with a concentration of 15wt%-25wt%.

[0014] Acid solution: A carbonic acid solution prepared by passing carbon dioxide into water.

[0015] Modifier: one or a mixture of Kymene series resins, JH1201 resin, polyvinyl alcohol resin, etc.

[0016] Water: Boiler steam condensate.

[0017] Principle: Use mechanical force to crush shrimp and crab shells into powder, reduce their particle size, form micrometer-sized shrimp and crab shell particles, and increase the specific surface area. Use carbonic acid and alkali solution to dissolve part of the calcium carbonate and protein in the shrimp and crab shell powder in turn, and a large amount of chitin will be exposed on the surface of the shrimp and crab shell particles, and chitosan will be formed. The calcium carbonate dissolved by carbonic acid will regenerate calcium carbonate as a reinforcing component of the subsequent adhesive after temperature change treatment; the process of dissolving protein by alkali solution will also cause chitin to deacetylate and produce functional groups such as -NH2, which has antibacterial and mildew-proof properties. The protein dissolved by alkali solution contains active functional groups such as -NH2, -COOH, and -OH, which can participate in the cross-linking and curing reaction as a component of the subsequent adhesive.

[0018] The advantages of the present invention are:

[0019] The method of the present invention realizes the utilization of all components of fishery processing waste, has no environmental burden, and has good environmental performance. The shrimp and crab shells are controllably depolymerized by mechanical force combined with chemical treatment methods to form shrimp and crab shell particles with amino functional groups on the surface, which are highly active and easy to be re-derivatized and modified; cross-linkable functional groups are then introduced by grafting and other methods, and the adhesive constructed by reassembly and cross-linking reaction of functional groups with the components separated from the depolymerized shrimp and crab shells has obvious antibacterial and mildew-proof effects; the cured adhesive layer and the produced artificial board combine the organic / inorganic hybrid shrimp and crab shell structure and the surface amino functional groups and their derivative components, and also have good heat-resistant, antibacterial and mildew-proof functions. DETAILED DESCRIPTION

[0020] In order to make the above features and advantages of the present invention more clearly understood, the following embodiments are given for detailed description. The methods of the present invention are all conventional methods in the art unless otherwise specified.

[0021] Example 1

[0022] A method for preparing a wood adhesive using shrimp and crab shells as all components, comprising the following steps:

[0023] (1) Wash the hairy crab shell raw material, dry it at 103°C for 2 hours, mechanically crush it into particles ≥60 mesh, and then obtain particles ≥3000 mesh by ball milling and ultrafine grinding for later use;

[0024] (2) 50 parts by weight of hairy crab shell particles were mixed with 100 parts by weight of water, carbon dioxide was introduced, the mixture was stirred at 60 rpm for 60 min at 10° C., the mixture was allowed to stand for 20 min, and the precipitate and supernatant were separated by filtration;

[0025] (3) The supernatant of step (2) is kept at 25° C. for 10 min, and the precipitate and the supernatant are separated by filtration; carbon dioxide is introduced into the supernatant to partially replace the water in step (2), and the supernatant is continuously circulated between step (2) and step (3);

[0026] (4) 10 parts by weight of the precipitate from step (2) was mixed with 20 parts by weight of a 15 wt% sodium hydroxide solution, the mixture was kept at 50° C. for 10 min, and the precipitate and the supernatant were filtered again to separate;

[0027] (5) 20 parts by weight of the precipitate of step (4) and 20 parts by weight of a modifier, a kymene series resin, were mixed and stirred at room temperature for 20 minutes, and then 30 parts by weight of the supernatant of step (4) and 10 parts by weight of the precipitate of step (3) were added to prepare a wood adhesive.

[0028] The control group was prepared by replacing the carbon dioxide and 15wt% sodium hydroxide solution in the above steps with air and distilled water, respectively, with no other changes.

[0029] Example 2

[0030] A method for preparing a wood adhesive using shrimp and crab shells as all components, comprising the following steps:

[0031] (1) Wash the swimming crab shell raw material, dry it at 103°C for 2 hours, mechanically crush it into particles ≥60 mesh, and then obtain particles ≥3000 mesh by ball milling and ultrafine grinding for later use;

[0032] (2) 65 parts by weight of swimming crab shell particles were mixed with 130 parts by weight of water, carbon dioxide was introduced, and the mixture was stirred at 60 rpm for 60 min at 10° C., allowed to stand for 20 min, and the precipitate and supernatant were separated by filtration;

[0033] (3) The supernatant of step (2) is kept at 35° C. for 10 min, and the precipitate and the supernatant are separated by filtration; carbon dioxide is introduced into the supernatant to partially replace the water in step (2), and the supernatant is continuously circulated between step (2) and step (3);

[0034] (4) 40 parts by weight of the precipitate from step (2) was mixed with 70 parts by weight of a 20 wt% potassium hydroxide solution, the mixture was kept at 70° C. for 20 min, and the precipitate and the supernatant were filtered again to separate the mixture;

[0035] (5) 30 parts by weight of the precipitate from step (4) and 30 parts by weight of the modifier JH1201 resin were mixed and stirred at room temperature for 20 minutes, and then 60 parts by weight of the supernatant from step (4) and 15 parts by weight of the precipitate from step (3) were added to prepare a wood adhesive.

[0036] The control group was prepared by replacing the carbon dioxide and 20 wt % potassium hydroxide solution in the above steps with air and distilled water, respectively, with no other changes.

[0037] Example 3

[0038] A method for preparing a wood adhesive using shrimp and crab shells as all components, comprising the following steps:

[0039] (1) Wash the lobster shell raw material, dry it at 103°C for 2 hours, mechanically crush it into particles ≥60 mesh, and then use ball milling and ultrafine grinding methods to obtain particles ≥3000 mesh for later use;

[0040] (2) 80 parts by weight of lobster shell particles were mixed with 160 parts by weight of water, carbon dioxide was introduced, and the mixture was stirred at 60 rpm for 60 min at 10° C., allowed to stand for 20 min, and the precipitate and supernatant were separated by filtration;

[0041] (3) The supernatant of step (2) is kept at 45°C for 10 minutes, and the precipitate and the supernatant are separated by filtration; carbon dioxide is introduced into the supernatant to partially replace the water in step (2), and the supernatant is continuously circulated between step (2) and step (3);

[0042] (4) 50 parts by weight of the precipitate from step (2) was mixed with 100 parts by weight of a 25 wt% aqueous ammonia solution, the mixture was kept at 90° C. for 30 min, and the precipitate and the supernatant were filtered again to separate the mixture;

[0043] (5) 40 parts by weight of the precipitate from step (4) and 40 parts by weight of a polyvinyl alcohol resin modifier are mixed and stirred at room temperature for 20 minutes, and then 90 parts by weight of the supernatant from step (4) and 20 parts by weight of the precipitate from step (3) are added to prepare a wood adhesive.

[0044] The control group was prepared by replacing the carbon dioxide and 25 wt % ammonia solution in the above steps with air and distilled water, respectively, with no other changes.

[0045] Performance: This adhesive can be used to produce particleboard, fiberboard, plywood and other artificial boards. For example, when used to make plywood, the double-sided glue application amount is 240-300g / m 2 , which can be achieved by manual gluing or roller gluing; at room temperature, with a surface pressure of 5-10MPa, pre-pressing for 0.5-1 hour, and then hot pressing at 1.0MPa, 130℃, 0.5-2 min / mm, the bonding strength can meet the requirements of Class II plywood in GB / T 9846-2015. The prepared artificial board has no free formaldehyde release, has natural antibacterial and mildew-proof effects, can be widely used in furniture or decoration industry, and has broad application prospects.

[0046]

[0047] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for preparing wood adhesive using shrimp and crab shells as all components, characterized in that: The method comprises the following steps: (1) washing the shrimp and crab shell raw materials, drying them at 103° C. for 2 h, mechanically crushing them into particles of ≥60 mesh, and then obtaining particles of ≥3000 mesh by ball milling and ultrafine grinding for later use; (2) mixing 50-80 parts by weight of shrimp and crab shell particles with 100-160 parts by weight of water, introducing carbon dioxide, stirring at 60 rpm for 60 min at 10° C., letting stand for 20 min, and filtering to separate the precipitate and the supernatant; (3) The supernatant of step (2) is kept at 25-45°C for 10 minutes, and the precipitate and the supernatant are separated by filtration; carbon dioxide is introduced into the supernatant to partially replace the water in step (2), and the supernatant is continuously circulated between step (2) and step (3); (4) mixing 10-50 parts by weight of the precipitate from step (2) with 20-100 parts by weight of an alkaline solution, keeping the mixture at 50-90° C. for 10-30 min, and filtering the mixture again to separate the precipitate and the supernatant; (5) 20-40 parts by weight of the precipitate of step (4) and 20-40 parts by weight of a modifier are mixed and stirred at room temperature for 20 minutes, and then 30-90 parts by weight of the supernatant of step (4) and 10-20 parts by weight of the precipitate of step (3) are added to prepare a wood adhesive; The modifier is one or a mixture of kymene series resins, JH1201 resin and polyvinyl alcohol resin.

2. The method according to claim 1, characterized in that The shrimp and crab shell raw materials are shells of one or more species of shrimp and crabs selected from the group consisting of hairy crabs, swimming crabs, king crabs, lobsters, and prawns.

3. The method according to claim 1, characterized in that The alkaline solution is a solution of one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, and ammonia water, with a concentration of 15wt%-25wt%.

4. The method according to claim 1, characterized in that The water is boiler steam condensate.

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