Oxidized sugar cross-linked vegetable protein-based adhesive, preparation method and application thereof, artificial composite board and preparation method thereof

Abstract

The invention relates to the technical field of artificial boards, in particular to an oxidized sugar cross-linked vegetable protein-based adhesive, a preparation method and application thereof, an artificial composite board and a preparation method thereof. The invention provides an oxidized sugar cross-linked vegetable protein-based adhesive. The oxidized sugar cross-linked vegetable protein-based adhesive comprises a cross-linked substance and water, the cross-linked substance is a cross-linked substance of oxidized sugar and vegetable protein; the oxidized sugar is obtained through an oxidation reaction of sugar and an oxidizing agent. Oxidized sugar formed by reaction of an oxidizing agent and sugar as raw materials is used as a cross-linking agent, aldehyde groups on the oxidized sugar have good affinity with hydroxyl, carboxyl, amino and the like in protein molecules, the oxidized sugar plays a role of a plasticizer in an adhesive system, and the viscosity of the oxidized sugar cross-linked vegetable protein-based adhesive is greatly reduced; when the oxidized sugar is applied to plate gluing, aldehyde groups in the oxidized sugar are subjected to Schiff base reaction with amino groups on vegetable proteins and are subjected to amidation reaction with carboxyl groups, so that a cross-linked network structure is formed, and the bonding strength and the water resistance of plates formed by gluing are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of artificial boards, and in particular to an oxidized sugar cross-linked plant protein-based adhesive and a preparation method and application thereof, an artificial composite board and a preparation method thereof. Background Art

[0002] With the continuous improvement of people's environmental awareness and the continuous improvement of the environmental protection requirements for artificial boards, environmentally friendly biomass-based adhesives such as plant protein-based adhesives, lignin adhesives, tannin adhesives, and starch adhesives have received more and more attention, and have gradually replaced the use of wood adhesives such as formaldehyde-based adhesives and their modified products (such as urea-formaldehyde, phenolic and melamine-formaldehyde-based wood adhesives). Plant protein-based adhesives have become the focus of most attention among biomass-based adhesives due to their advantages such as abundant raw material resources, low price, renewable, biodegradable, easy processing, and easy chemical modification. After the molecular chains of plant protein molecules in plant protein-based adhesives are unfolded, the intermolecular interactions are enhanced, which increases the viscosity of soy protein adhesives, resulting in excessive viscosity of plant protein-based adhesives, resulting in lack of fluidity, uneven dispersion during the hot pressing stage of plywood preparation, hindering the bonding process, and thus reducing the bonding strength of plywood. Summary of the invention

[0003] In view of this, the object of the present invention is to provide an oxidized sugar cross-linked plant protein-based adhesive and a preparation method and application thereof, an artificial composite board and a preparation method thereof. The oxidized sugar cross-linked plant protein-based adhesive provided by the present invention has low viscosity.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The invention provides an oxidized sugar cross-linked plant protein-based adhesive, which comprises a cross-linking material and water; the cross-linking material is a cross-linked material of oxidized sugar and plant protein; the oxidized sugar is obtained by an oxidation reaction of sugar and an oxidant; and the viscosity of the oxidized sugar cross-linked plant protein-based adhesive is 300-20000 mPa·s.

[0006] Preferably, the sugar includes one or more of glucose, fructose, galactose, sucrose, maltose, starch and cellulose.

[0007] Preferably, the oxidant includes one or more of potassium permanganate, potassium dichromate, sodium periodate, hydrogen peroxide, sodium hypochlorite and sodium persulfate;

[0008] The mass ratio of the sugar to the oxidant is 1:0-1, and the amount of the oxidant is not zero.

[0009] Preferably, the plant protein includes one or more of soybean meal, soybean protein isolate, tea oil cake meal, cottonseed protein, peanut protein, corn protein, wheat protein and flax protein.

[0010] Preferably, the method for preparing the oxidized sugar comprises the following steps:

[0011] The sugar and the oxidant are mixed and subjected to an oxidation reaction to obtain the oxidized sugar.

[0012] The present invention provides a method for preparing the oxidized sugar cross-linked plant protein-based adhesive described in the above technical solution, comprising the following steps:

[0013] The vegetable protein, oxidized sugar and water are mixed and subjected to a cross-linking reaction to obtain the oxidized sugar cross-linked vegetable protein-based adhesive.

[0014] The present invention provides the use of the oxidized sugar cross-linked plant protein-based adhesive described in the above technical scheme or the oxidized sugar cross-linked plant protein-based adhesive prepared by the preparation method described in the above technical scheme in board bonding.

[0015] The present invention provides an artificial composite board, comprising a plurality of layers of veneers stacked in sequence; an adhesive layer is arranged between two adjacent layers of veneers;

[0016] The adhesive used in the adhesive layer is the oxidized sugar cross-linked plant protein-based adhesive described in the above technical solution or the oxidized sugar cross-linked plant protein-based adhesive prepared by the preparation method described in the above technical solution.

[0017] The present invention provides a method for preparing the artificial composite board described in the above technical solution, comprising the following steps:

[0018] Applying glue between two adjacent veneers and then performing hot pressing and curing to obtain the artificial composite board;

[0019] The adhesive used for sizing is the oxidized sugar cross-linked plant protein-based adhesive described in the above technical solution or the oxidized sugar cross-linked plant protein-based adhesive prepared by the preparation method described in the above technical solution.

[0020] Preferably, the temperature of the hot pressing curing is 140-200° C., the pressure is ≥0.5 MPa, and the time is ≥3 min.

[0021] The present invention provides an oxidized sugar cross-linked plant protein-based adhesive, which includes a cross-linking product and water; the cross-linking product is a cross-linked product of oxidized sugar and plant protein; the oxidized sugar is obtained by oxidation reaction of sugar and oxidant; the viscosity of the oxidized sugar cross-linked plant protein-based adhesive is 300-20000 mPa·s. The present invention uses oxidized sugar formed by the reaction of oxidant and sugar as raw materials as a cross-linking agent, and the aldehyde group on the oxidized sugar has good affinity with the hydroxyl group, carboxyl group, amino group, etc. in the protein molecule, and plays the role of a plasticizer in the adhesive system, greatly reducing the viscosity of the oxidized sugar cross-linked plant protein-based adhesive. When the oxidized sugar cross-linked plant protein-based adhesive provided by the present invention is used in the bonding of boards, the aldehyde group in the oxidized sugar reacts with the amino group on the plant protein to undergo a Schiff base reaction and an amidation reaction with the carboxyl group, thereby forming a cross-linked network structure, which improves the bonding strength and water resistance of the board formed by bonding. At the same time, under normal temperature, the protein-based adhesive involved in the present invention does not use volatile organic matter for cross-linking, and has the advantages of being environmentally friendly, safe and non-toxic.

[0022] The present invention provides a method for preparing the oxidized sugar cross-linked plant protein-based adhesive described in the above technical solution, comprising the following steps: mixing sugar, an oxidant, water and plant protein to obtain the oxidized sugar cross-linked plant protein-based adhesive. The preparation method provided by the present invention is simple to operate, low in cost, and suitable for industrial production. DETAILED DESCRIPTION

[0023] The invention provides an oxidized sugar cross-linked plant protein-based adhesive, which comprises a cross-linking material and water; the cross-linking material is a cross-linked material of oxidized sugar and plant protein; the oxidized sugar is obtained by an oxidation reaction of sugar and an oxidant; and the viscosity of the oxidized sugar cross-linked plant protein-based adhesive is 300-20000 mPa·s.

[0024] Unless otherwise specified, the materials used in the present invention are all commercially available products in the art.

[0025] In the present invention, the viscosity of the oxidized sugar cross-linked plant protein-based adhesive is 300-20000 mPa·s, preferably 700-5000 mPa·s, more preferably 1000-3000 mPa·s, and most preferably 2000-2500 mPa·s; the dry bonding strength of the oxidized sugar cross-linked plant protein-based adhesive is preferably 0.7-2.7 MPa, more preferably 1.2-2.5 MPa, and most preferably 1.5-2 MPa; the wet bonding strength of the oxidized sugar cross-linked plant protein-based adhesive is preferably 0.7-1.68 MPa, more preferably 0.76-1.17 MPa, and most preferably 0.9-1 MPa.

[0026] In the present invention, the sugar preferably includes one or more of glucose, fructose, galactose, sucrose, maltose, starch and cellulose, and is more preferably glucose; when the sugar is a mixture of different types of sugars, the present invention does not have any special restrictions on the ratio of different types of sugars, and any ratio is acceptable.

[0027] In the present invention, the oxidant preferably includes one or more of potassium permanganate, potassium dichromate, sodium periodate, hydrogen peroxide, sodium hypochlorite and sodium persulfate, more preferably sodium periodate; when the oxidant is a mixture of different types of oxidants, the present invention does not have any special restrictions on the ratio of different types of oxidants, and any ratio is acceptable. In the present invention, the mass ratio of the sugar to the oxidant is preferably 1:0-1, and the amount of the oxidant is not 0, more preferably 1:0.05-0.5, further preferably 1:0.1-0.3, and most preferably 1:0.1-0.2.

[0028] In the present invention, the method for preparing the oxidized sugar preferably comprises the following steps: mixing sugar and an oxidant, and performing an oxidation reaction to obtain the oxidized sugar.

[0029] In the present invention, the temperature of the oxidation reaction is preferably 20 to 55°C, more preferably 25 to 40°C, and most preferably 25 to 30°C; the time of the oxidation reaction is preferably 2 to 10 min, more preferably 3 to 7 min, and most preferably 4 to 6 min. In the present invention, the mixing preferably also includes adding water for mixing. In the present invention, the water preferably includes deionized water; the mass ratio of the sugar to water is preferably 1:1 to 8, more preferably 1:2 to 6, further preferably 1:2 to 5, and most preferably 1:3 to 4. In the present invention, the mixing preferably includes stirring and mixing. The present invention does not specifically limit the stirring speed of the stirring and mixing, as long as the sugar, oxidant and water are evenly mixed.

[0030] In the present invention, the plant protein preferably includes one or more of soybean meal, soy protein isolate, tea cake meal, cottonseed protein, peanut protein, corn protein, wheat protein and jatropha protein, more preferably soybean meal or soy protein isolate; when the plant protein is a mixture of different types of plant proteins, the present invention has no special limitation on the ratio of different types of plant proteins, and any ratio is acceptable.

[0031] The present invention provides a method for preparing the oxidized sugar cross-linked plant protein-based adhesive described in the above technical solution, comprising the following steps: mixing plant protein, oxidized sugar and water, and performing a cross-linking reaction to obtain the oxidized sugar cross-linked plant protein-based adhesive. In the present invention, the temperature of the cross-linking reaction is preferably 20-55°C, more preferably 25-40°C, and most preferably 25-30°C; the time of the cross-linking reaction is preferably 5-15min, more preferably 6-12min, and most preferably 8-11min; the mixing preferably includes stirring and mixing. The present invention does not specifically limit the stirring speed of the stirring and mixing, as long as the oxidized sugar, water and plant protein can be mixed uniformly. In the present invention, the ratio of the total mass of the oxidized sugar and water to the mass of the plant protein is preferably 0-8:1, and the total mass of the oxidized sugar and water is not 0, more preferably 1-6:1, further preferably 2-6:1, and most preferably 4-5:1. In the present invention, the oxidized sugar and water are preferably used in the form of an oxidized sugar aqueous solution. The present invention uses oxidized sugar as a cross-linking agent, which reacts with plant protein to produce a Schiff base reaction, plays a role as a plasticizer, and greatly reduces the viscosity of the oxidized sugar cross-linked plant protein-based adhesive.

[0032] The present invention provides the use of the oxidized sugar cross-linked plant protein-based adhesive described in the above technical solution or the oxidized sugar cross-linked plant protein-based adhesive prepared by the preparation method described in the above technical solution in board gluing. The oxidized sugar cross-linked plant protein-based adhesive provided by the present invention has low viscosity, high dry bonding strength and wet bonding strength, and when used in board gluing, improves the bonding strength and water resistance of the board formed by gluing.

[0033] The present invention provides an artificial composite board, comprising a plurality of layers of veneers stacked in sequence; an adhesive layer is provided between two adjacent layers of veneers; the adhesive used in the adhesive layer is the oxidized sugar cross-linked plant protein-based adhesive described in the above technical solution or the oxidized sugar cross-linked plant protein-based adhesive prepared by the preparation method described in the above technical solution. The present invention does not specifically limit the number of layers of the artificial composite board, and it can be specifically limited according to actual needs, and it is preferably 3 layers. The present invention does not specifically limit the material of the veneer, and conventional boards in the field can be used, and it is preferably a fast-growing poplar wood board; the thickness of the fast-growing poplar wood board is preferably 0.5 to 3 mm, more preferably 1 to 2.6 mm, and most preferably 2.2 to 2.6 mm; the moisture content of the fast-growing poplar wood board is preferably 8 to 10%, more preferably 8.5 to 9.5%, and most preferably 9 to 9.2%.

[0034] The present invention provides a method for preparing the artificial composite board described in the above technical scheme, comprising the following steps: applying glue between two adjacent layers of veneer boards and then performing hot pressing and curing, wherein the adhesive is cured to form an adhesive layer to obtain the artificial composite board; the adhesive is the oxidized sugar cross-linked plant protein-based adhesive described in the above technical scheme or the oxidized sugar cross-linked plant protein-based adhesive obtained by the preparation method described in the above technical scheme.

[0035] In the present invention, the sizing amount is preferably 180 to 220 g / m 2 , more preferably 190 to 200 g / m 2 , the most preferred is 195 to 200 g / m 2 .

[0036] In the present invention, the temperature of the hot pressing curing is preferably 140-200°C, more preferably 140-160°C, and most preferably 150-160°C; the pressure of the hot pressing curing is preferably ≥0.5MPa, more preferably 0.5-1MPa, and most preferably 0.7-1MPa; the time of the hot pressing curing is ≥3min, more preferably 3-7min, and most preferably 4-6min. The present invention is beneficial to controlling the degree of Schiff base reaction between the aqueous solution of oxidized sugar and plant protein by limiting the temperature, pressure and time of hot pressing curing, which is beneficial to forming a stable cross-linked structure, improving the bonding strength of the oxidized sugar cross-linked plant protein-based adhesive, and reducing the viscosity of the oxidized sugar cross-linked plant protein-based adhesive.

[0037] In the present invention, when the number of layers of the artificial composite board is 3, the preparation method of the artificial composite board preferably includes the following steps: performing a first gluing on any surface of the base plate and the panel, performing a second gluing and a third gluing on the two surfaces of the core plate respectively, and stacking the base plate, the core plate and the panel in sequence to obtain a composite board blank; the gluing surface of the base plate is in contact with the core plate, and the gluing surface of the panel is in contact with the core plate; and hot pressing and curing the composite board blank to obtain the artificial composite board.

[0038] In the present invention, the sizing amounts of the first sizing, the second sizing and the third sizing are independently preferably 180 to 220 g / m 2 , more preferably 190 to 200 g / m 2 , the most preferred is 195 to 200 g / m 2 .

[0039] To further illustrate the present invention, an oxidized sugar cross-linked plant protein-based adhesive and its preparation method and application, an artificial composite board and its preparation method provided by the present invention are described in detail below in combination with embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0040] Example 1

[0041] In parts by mass, 10 parts of glucose, 2 parts of sodium periodate and 80 parts of deionized water were mixed, stirred at 25° C. for 5 minutes, and then 20 parts of soy protein isolate were added and stirred for 5 minutes to obtain an oxidized sugar cross-linked plant protein-based adhesive.

[0042] Example 2

[0043] In parts by mass, 10 parts of glucose, 2.5 parts of sodium periodate and 80 parts of deionized water were mixed, stirred at 25° C. for 5 minutes, and then 20 parts of soy protein isolate were added and stirred for 5 minutes to obtain an oxidized sugar cross-linked plant protein-based adhesive.

[0044] Example 3

[0045] In parts by mass, 10 parts of glucose, 3 parts of sodium periodate and 80 parts of deionized water were mixed, stirred at 25° C. for 5 minutes, and then 20 parts of soy protein isolate were added and stirred for 5 minutes to obtain an oxidized sugar cross-linked plant protein-based adhesive.

[0046] Example 4

[0047] In parts by mass, 10 parts of glucose, 2 parts of sodium periodate and 70 parts of deionized water were mixed, stirred at 25° C. for 5 minutes, and then 20 parts of soybean meal were added and stirred for 5 minutes to obtain an oxidized sugar cross-linked plant protein-based adhesive.

[0048] Example 5

[0049] In parts by mass, 10 parts of glucose, 2.5 parts of sodium periodate and 70 parts of deionized water were mixed, stirred at 25° C. for 5 minutes, and then 20 parts of soybean meal were added and stirred for 5 minutes to obtain an oxidized sugar cross-linked plant protein-based adhesive.

[0050] Example 6

[0051] In parts by mass, 10 parts of glucose, 3 parts of sodium periodate and 70 parts of deionized water were mixed, stirred at 25° C. for 5 minutes, and then 20 parts of soybean meal were added and stirred for 5 minutes to obtain an oxidized sugar cross-linked plant protein-based adhesive.

[0052] Comparative Example 1

[0053] By weight, 20 parts of soy protein isolate were dissolved in 80 parts of deionized water at 25° C. to obtain a soy protein isolate solution.

[0054] Comparative Example 2

[0055] By weight, 20 parts of soybean meal were dissolved in 70 parts of deionized water at 25° C. to obtain a soybean meal solution.

[0056] Example 7

[0057] Using the oxidized sugar cross-linked plant protein-based adhesive prepared in any one of Examples 1 to 6, the soy protein isolate solution prepared in Comparative Example 1, or the soybean meal solution prepared in Comparative Example 2 as an adhesive, an artificial composite board is prepared:

[0058] Three fast-growing poplar boards with a thickness of 1.5 mm and a moisture content of 8 to 10% are used as raw materials. Two fast-growing poplar boards are selected and coated on either surface at a temperature of 200 g / m 2 The glue application amount was 200g / m 2 The base plate, the core plate and the panel are sequentially stacked in this order, with the glued surfaces of the base plate and the panel directly in contact with the core plate, to obtain a composite board blank; the obtained composite board blank is hot-pressed and cured at 160° C. and 1.0 MPa for 5 minutes to obtain the artificial composite board (three layers).

[0059] The viscosity of the oxidized sugar cross-linked plant protein-based adhesive, the dry bonding strength and the wet bonding strength of the artificial composite board were tested. The test method is as follows:

[0060] Dry bonding strength and wet bonding strength: The test is carried out in accordance with GB / T 17657-2013 "Test methods for physical and chemical properties of wood-based panels and veneer wood-based panels". The wet strength sample processing method is: soak the wood-based composite board in boiling water at a temperature of 93±3℃ for 3 hours. After soaking, take out the wood-based composite board sample and test it within 0.5 hours.

[0061] Viscosity: The viscosity of the adhesive was measured using a NDJ-8S rotational rheometer (Shanghai Jinghai Instrument Co., Ltd.). First, the viscometer was adjusted horizontally to ensure that the rotor was installed perpendicular to the ground; then, a suitable rotor was selected for installation according to the viscosity of the adhesive, and the speed of the instrument was adjusted. The adhesive at different positions in the container was measured 5 times and the average value was taken.

[0062] The test results of the artificial composite panels are shown in Table 1, where “——” indicates wet and unbonded.

[0063] Table 1 Performance test results of artificial composite panels

[0064] Example Viscosity (mPa·s) Dry bonding strength (MPa) Wet bonding strength (MPa) Example 1 1035 1.94±0.22 0.93±0.10 Example 2 926 2.01±0.27 1.06±0.08 Example 3 637 2.11±0.17 1.17±0.09 Example 4 2604 1.85±0.25 0.76±0.02 Example 5 2748 1.68±0.14 0.79±0.06 Example 6 2354 2.07±0.09 0.84±0.04 Comparative Example 1 89761 1.62±0.27 —— Comparative Example 2 43168 1.47±0.18 ——

[0065] As can be seen from Table 1, the viscosity of the oxidized sugar cross-linked plant protein-based adhesive prepared by the present invention is 637-2748 mPa·s, and the viscosity is low; the dry bonding strength of the oxidized sugar cross-linked plant protein-based adhesive is 1.68-2.11 MPa, and the wet bonding strength is 0.76-1.17 MPa, both exceeding the requirements of the national standard Class I board (0.7 MPa), and has good mechanical properties and water resistance.

[0066] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An oxidized sugar cross-linked plant protein-based adhesive, characterized in that: The composition includes a cross-linking material and water; the cross-linking material is a cross-linking material of oxidized sugar and plant protein; the oxidized sugar is obtained by oxidation reaction of sugar and oxidant; the viscosity of the oxidized sugar cross-linked plant protein-based adhesive is 300-20000mPa·s.

2. The oxidized sugar cross-linked plant protein-based adhesive according to claim 1, characterized in that: The sugar includes one or more of glucose, fructose, galactose, sucrose, maltose, starch and cellulose.

3. The oxidized sugar cross-linked plant protein-based adhesive according to claim 2, characterized in that: The oxidant includes one or more of potassium permanganate, potassium dichromate, sodium periodate, hydrogen peroxide, sodium hypochlorite and sodium persulfate; The mass ratio of the sugar to the oxidant is 1:0-1, and the amount of the oxidant is not zero.

4. The oxidized sugar cross-linked plant protein-based adhesive according to claim 1, characterized in that: The plant protein comprises one or more of soybean meal, soybean protein isolate, tea oil cake meal, cottonseed protein, peanut protein, corn protein, wheat protein and flax protein.

5. The oxidized sugar cross-linked plant protein-based adhesive according to any one of claims 1 to 3, characterized in that: The method for preparing the oxidized sugar comprises the following steps: The sugar and the oxidant are mixed and subjected to an oxidation reaction to obtain the oxidized sugar.

6. The method for preparing the oxidized sugar cross-linked plant protein-based adhesive according to any one of claims 1 to 5, characterized in that: The following steps are involved: The vegetable protein, oxidized sugar and water are mixed and subjected to a cross-linking reaction to obtain the oxidized sugar cross-linked vegetable protein-based adhesive.

7. Use of the oxidized sugar cross-linked plant protein-based adhesive according to any one of claims 1 to 5 or the oxidized sugar cross-linked plant protein-based adhesive prepared by the preparation method according to claim 6 in board gluing.

8. An artificial composite board, characterized in that: It comprises a plurality of layers of veneers stacked in sequence; an adhesive layer is arranged between two adjacent layers of veneers; The adhesive used in the adhesive layer is the oxidized sugar cross-linked plant protein-based adhesive described in any one of claims 1 to 5 or the oxidized sugar cross-linked plant protein-based adhesive prepared by the preparation method described in claim 6.

9. The method for preparing the artificial composite board according to claim 8, characterized in that: The following steps are involved: Applying glue between two adjacent veneers and then performing hot pressing and curing to obtain the artificial composite board; The adhesive used for sizing is the oxidized sugar cross-linked plant protein-based adhesive described in any one of claims 1 to 5 or the oxidized sugar cross-linked plant protein-based adhesive prepared by the preparation method described in claim 6.

10. The preparation method according to claim 9, characterized in that: The temperature of the hot pressing curing is 140-200° C., the pressure is ≥0.5 MPa, and the time is ≥3 min.