CN111363482A - High-strength water-resistant plant protein adhesive and preparation method thereof - Google Patents

Abstract

The invention discloses a high-strength water-resistant vegetable protein adhesive and a preparation method thereof, wherein the adhesive is prepared from vegetable protein powder and a gelling agent, the mass ratio of the vegetable protein powder to the gelling agent is (30-80) to 100, and the gelling agent comprises the following raw materials in parts by weight: 800-1000 parts of water; the protein modifier comprises the following components in percentage by mass: 8-20 parts of maleic anhydride, 0.3-1 part of zinc chloride, 4-6 parts of borax and 15-20 parts of sodium fluosilicate; 50-200 parts of a wet strength agent; 10-20 parts of a crosslinking agent; 1-3 parts of a thickening agent. The invention takes water as a dispersion medium to dissolve the protein modifier, the thickening agent, the cross-linking agent and the wet strength agent in the water to form a stable gelatinizing agent solution, the dissolving process is simple without heating, the gelatinizing agent and the plant protein powder are stirred and mixed uniformly according to a proportion when in use, and the production process has no energy consumption, no waste water, waste gas and waste residue discharge, safety, simplicity, convenient use and low cost.

Description

High-strength water-resistant plant protein adhesive and preparation method thereof

Technical Field

The invention relates to the technical field of wood adhesives, in particular to a high-strength water-resistant plant protein adhesive and a preparation method thereof.

Background

The strong development of the wood industry greatly improves the dosage of the wood adhesive, thereby driving the rapid development of the wood adhesive industry. At present, urea-formaldehyde glue and phenol-formaldehyde glue are the most commonly used adhesives, and the two petroleum-based adhesives belong to non-biodegradable materials, are easy to cause waste accumulation to deteriorate the environment, release carcinogenic substances such as free formaldehyde and phenol in the processing and using processes, and have serious threat to the health of human bodies invisibly. Protein adhesive is increasingly paid more attention as a biomass adhesive based on renewable resources and an environment-friendly biological material, and is gradually a hotspot of research. At present, the production process of the protein adhesive is complex, heating is needed in the production process, and strong corrosive acids such as sulfuric acid and the like are also needed to be added in some protein adhesives, so that great potential safety hazards exist. For example, a soybean glue with publication No. CN103184032A and its preparation method require the temperature of mixed liquid to be 80-96 deg.C, a water-resistant soybean adhesive with publication No. CN107090270A and its preparation method, sulfuric acid is added and the temperature is 60-80 deg.C, and the production process is too complex.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides the high-strength water-resistant vegetable protein adhesive which is simple in production process, free of heating, convenient to use and long in storage time, and the preparation method thereof.

The invention relates to a high-strength water-resistant vegetable protein adhesive which is prepared from vegetable protein powder and a gelling agent, wherein the mass ratio of the vegetable protein powder to the gelling agent is (30-80) to 100, and the gelling agent comprises the following raw materials in parts by weight: 800-1000 parts of water; the protein modifier comprises the following components in percentage by mass: 8-20 parts of maleic anhydride, 0.3-1 part of zinc chloride, 4-6 parts of borax and 15-20 parts of sodium fluosilicate; 50-200 parts of a wet strength agent; 10-20 parts of a crosslinking agent; 1-3 parts of a thickening agent.

Preferably, the vegetable protein powder is one of defatted soybean powder, flour or a mixture of the defatted soybean powder and the flour.

Preferably, the mass ratio of the defatted soybean flour to the gelling agent is (30-45) to 100; the mass ratio of the flour to the gelatinizing agent is (60-80) to 100; the mass ratio of the mixture of the defatted soybean flour and the flour to the gelatinizing agent is (40-70) to 100.

Preferably, the wet strength agent is polyamide epichlorohydrin, the crosslinking agent is glucose, and the thickening agent is one of xanthan gum and polyacrylamide or a mixture of the xanthan gum and the polyacrylamide in any proportion.

The invention also provides a preparation method of the high-strength water-resistant vegetable protein adhesive, which comprises the following steps:

1) adding metered water into a container with a stirrer, starting the stirrer, then adding a protein modifier, a thickening agent, a wet strength agent and a crosslinking agent, and fully stirring at normal temperature until the protein modifier, the thickening agent, the wet strength agent and the crosslinking agent are completely dissolved to obtain a gelling agent;

2) and (3) mixing the prepared gelling agent and the plant protein powder according to the mass ratio, and fully and uniformly stirring to obtain the high-strength water-resistant plant protein adhesive.

The reactive groups contained in the basic amino acid structural unit of the vegetable protein, such as amino, carboxyl and the like, can interact with wood fibers and have good bonding performance. The chemical properties of plant proteins are mainly influenced by intermolecular forces, covalent bonds, hydrogen bonds, and other factors. The invention destroys the hydrogen bond by chemical means, makes the molecule fully spread, and forms a layer of macromolecular long-chain interweaved adhesive layer which can be firmly adsorbed on the bonded phase interface in the cross-linking and curing process.

According to the invention, through the addition of the protein modifier, the cross-linking agent, the wet strength agent and the thickening agent, the plant protein is exposed through the fast water groups in the modified protein, and the combination of the fast water groups with water to form hydrogen bonds is hindered, so that the damage of water to the vegetable protein adhesive colloid is reduced, and the water-resistant gluing performance of the plant protein adhesive colloid is improved.

The invention relates to a plant protein molecule belonging to amphoteric molecule, which uses maleic anhydride as strong acid modifier, combines the action of zinc chloride on cellulose and the reaction of zinc chloride with carboxyl in protein molecule to promote the water resistance of protein adhesive, and simultaneously considers adding alkali modifier sodium fluosilicate and borax with mildew-proof function to form a composite modifier.

The invention especially considers the characteristic that the polyamide epichlorohydrin can form a compound with protein molecules under the condition of room temperature and a wider PH value (4-9), and the water resistance of the vegetable protein adhesive is enhanced by introducing the epoxy group.

The glucose used in the invention is a polyhydroxy aldehyde which can be cross-linked with protein to promote the solidification of protein adhesive.

The protein modifier, the wet strength agent, the cross-linking agent and the thickening agent selected by the invention have the characteristic of high solubility at room temperature, and practice proves that the formed solution is stable to store.

In conclusion, the protein modifier, the thickening agent, the cross-linking agent and the wet strength agent are dissolved in water by taking water as a dispersion medium to form a stable gelatinizing agent solution, the dissolving process is simple, heating is not needed, and the gelatinizing agent and the plant protein powder are stirred and mixed uniformly in proportion when the gelatinizing agent solution is used. The high-strength water-resistant plant protein adhesive disclosed by the invention realizes no energy consumption, no waste water, waste gas and waste residue discharge, is safe and simple in production process, relatively simple and convenient to use, low in cost and suitable for all artificial board production enterprises to produce, prepare and use by themselves. The storage time of the gel forming agent is more than half a year, and the defatted soybean flour and the flour can be stored for more than one year.

Detailed Description

The following examples are given to illustrate the present invention but are not intended to limit the scope of the present invention.

Example 1

Adding 950 kilograms of water into a container with a stirrer with an effective volume of 2 cubic meters, starting the stirrer, adding 20 kilograms of maleic anhydride, 0.5 kilogram of zinc chloride, 4 kilograms of borax, 20 kilograms of sodium fluosilicate, 2.5 kilograms of polyacrylamide, 0.5 kilogram of xanthan gum, 20 kilograms of glucose and 100 kilograms of polyamide epichlorohydrin, fully stirring until the materials are completely dissolved, and canning for later use.

100 kg of the gelatinizing agent liquid and 42 kg of the defatted soybean flour are uniformly stirred in a glue mixing barrel, glue is coated on a gluing machine (the glue roller is provided with threads to facilitate glue coating), glue is coated on the surface of a core board assembly for producing the core board assembly according to 240 g/square meter of each glue layer, the opening and the standing time are 3 hours, then cold pressing is carried out, the cold pressing pressure is controlled to be 10 kg/square centimeter per unit pressure, the cold pressing time is controlled to be 40 minutes, hot pressing is finished within 20 hours after the cold pressing is finished, the hot pressing temperature is controlled to be 120 ℃, the hot pressing time is controlled to be 15 minutes, and the hot pressing pressure is controlled to be 6.5 kg/square centimeter per unit pressure.

The bonding strength, formaldehyde emission, water content, static bending strength and dipping stripping performance of the adhesive are detected as follows: inspection according to GB/T5849-2016 core Board

Example 2

Adding 800 kg of water into a container with a stirrer with an effective volume of 2 cubic meters, starting the stirrer, adding 16 kg of maleic anhydride, 0.5 kg of zinc chloride, 5 kg of borax, 18 kg of sodium fluosilicate, 3 kg of polyacrylamide, 10 kg of glucose and 200 kg of polyamide epoxy chloropropane, fully stirring until the materials are completely dissolved, and canning for later use.

100 kg of the gelatinizing agent liquid is added with 40 kg of defatted soybean flour and 10 kg of flour and then uniformly stirred in a gelatinizing barrel, the gelatinizing machine is used for gelatinizing 18 cm full-eucalyptus multilayer boards (rubber rollers are provided with threads to facilitate gelatinizing), 260 g per square meter of each rubber layer is used for gelatinizing, the opening and the standing time are 4 hours, then cold pressing is carried out, the cold pressing pressure is controlled to be 12 kg/square centimeter per unit pressure, the cold pressing time is controlled to be 60 minutes, hot pressing is completed within 20 hours after the cold pressing is completed, the hot pressing temperature is controlled to be 125 ℃, the hot pressing time is controlled to be 18 minutes, and the hot pressing pressure is controlled to be 7 kg/square centimeter per unit pressure.

The bonding strength, formaldehyde emission, water content and dipping stripping performance of the adhesive are detected as follows: the inspection is carried out according to GB/T9846-2015 common plywood; GB/T18580-2001

Example 3

1000 kg of water is added into a container with a stirrer with an effective volume of 2 cubic meters, the stirrer is started, 8 kg of maleic anhydride, 0.3 kg of zinc chloride, 6 kg of borax, 15 kg of sodium fluosilicate, 3 kg of xanthan gum, 14 kg of glucose and 50 kg of polyamide epichlorohydrin are added, fully stirred until the components are completely dissolved, and then the mixture is canned for standby.

100 kg of the gelatinizing agent liquid and 60 kg of flour are uniformly stirred in a glue mixing barrel, glue is coated on a gluing machine (the glue roller is provided with threads to facilitate gluing), 350 g of glue is coated on each core board for producing the core boards of the blockboards, the opening and the standing time are 0.5 hour, then the boards are arranged for hot pressing of a board splicing machine (with side pressure), the hot pressing temperature is controlled at 145 ℃, the hot pressing time is 140 seconds, the board splicing process is smooth, no scattered board is generated, the steel plates are not stuck, and the strength of the core boards is good.

The water content and formaldehyde detection are as follows: inspection according to GB/T5849-2016 core Board

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, many variations and modifications can be made without departing from the inventive concept of the present invention, and these are within the scope of the present invention.

Claims (5)

1. A high-strength water-resistant vegetable protein adhesive is characterized in that: the adhesive is prepared from plant protein powder and a gelling agent, wherein the mass ratio of the plant protein powder to the gelling agent is (30-80) to 100, and the gelling agent comprises the following raw materials in parts by weight: 800-1000 parts of water; the protein modifier comprises the following components in percentage by mass: 8-20 parts of maleic anhydride, 0.3-1 part of zinc chloride, 4-6 parts of borax and 15-20 parts of sodium fluosilicate; 50-200 parts of a wet strength agent; 10-20 parts of a crosslinking agent; 1-3 parts of a thickening agent.

2. A high strength water resistant vegetable protein adhesive as defined in claim 1, wherein: the vegetable protein powder is one or a mixture of defatted soybean flour and flour.

3. A high strength water resistant vegetable protein adhesive as defined in claim 2, wherein: the mass ratio of the defatted soybean flour to the gelling agent is (30-45) to 100; the mass ratio of the flour to the gelatinizing agent is (60-80) to 100; the mass ratio of the mixture of the defatted soybean flour and the flour to the gelatinizing agent is (40-70) to 100.

4. A high strength water resistant vegetable protein adhesive as defined in claim 1, wherein: the wet strength agent is polyamide epichlorohydrin, the cross-linking agent is glucose, and the thickening agent is one of xanthan gum and polyacrylamide or a mixture of the two in any proportion.

5. The method of preparing the high strength water resistant vegetable protein adhesive of any one of claims 1-4, wherein the method comprises the steps of:

1) adding metered water into a container with a stirrer, starting the stirrer, then adding a protein modifier, a thickening agent, a wet strength agent and a crosslinking agent, and fully stirring at normal temperature until the protein modifier, the thickening agent, the wet strength agent and the crosslinking agent are completely dissolved to obtain a gelling agent;

2) and (3) mixing the prepared gelling agent and the plant protein powder according to the mass ratio, and fully and uniformly stirring to obtain the high-strength water-resistant plant protein adhesive.