阅读说明：本技术 一种大豆蛋白胶黏剂及其制备方法与应用 (Soybean protein adhesive and preparation method and application thereof ) 是由 高鹏 韩萌萌 项柳 孙刚 高强 李建章 李京超 于 2021-08-06 设计创作，主要内容包括：本发明涉及生物质胶黏剂技术领域,具体公开了一种大豆蛋白胶黏剂及其制备方法与应用。本发明大豆蛋白胶黏剂包括大豆蛋白粉、水、交联剂和杂化剂；所述交联剂为由淀粉与3,4-二羟基苯甲酸反应制得的邻苯二酚基多糖交联剂；所述杂化剂为原位生成的碳酸钙。本发明的胶黏剂交联密度大,固化时间短,阻燃性能优良,工艺性好,制备的胶黏剂性能稳定、弱界面层明显下降,成本降低,耐水胶接性能好,产品质量稳定。能够满足胶合板胶黏剂的耐水与工艺要求,保证了生物质胶黏剂的实用性能。(The invention relates to the technical field of biomass adhesives, and particularly discloses a soy protein adhesive and a preparation method and application thereof. The soybean protein adhesive comprises soybean protein powder, water, a cross-linking agent and a hybridization agent; the cross-linking agent is a catechol polysaccharide cross-linking agent prepared by the reaction of starch and 3, 4-dihydroxy benzoic acid; the hybridization agent is calcium carbonate generated in situ. The adhesive disclosed by the invention is high in crosslinking density, short in curing time, excellent in flame retardant property and good in manufacturability, the prepared adhesive is stable in performance, a weak interface layer is obviously reduced, the cost is reduced, the water-resistant bonding performance is good, and the product quality is stable. The water-resistant and technological requirements of the plywood adhesive can be met, and the practical performance of the biomass adhesive is ensured.)

1. The soy protein adhesive is characterized by comprising soy protein powder, water, a cross-linking agent and a hybridization agent; the cross-linking agent is a catechol polysaccharide cross-linking agent prepared by the reaction of starch and 3, 4-dihydroxy benzoic acid; the hybridization agent is calcium carbonate generated in situ.

2. The soy protein adhesive as claimed in claim 1, wherein the mass ratio of the starch to the 3, 4-dihydroxybenzoic acid is 1 (0.8-1.2), preferably 1: 1.2.

3. The soy protein adhesive as claimed in claim 2, wherein the mass ratio of the cross-linking agent to the soy protein powder is 1: (5-7).

4. The soy protein adhesive as claimed in claim 3, wherein the mass ratio of the soy protein powder to the hybridization agent is 30: (0.5-1).

5. The soy protein adhesive as claimed in claim 4, wherein the mass ratio of the cross-linking agent to the soy protein powder is 1: 5; the mass ratio of the soybean protein powder to the hybridization agent is 30: 1.

6. the soy protein adhesive as claimed in any one of claims 1 to 5, comprising in parts by weight: 28-30 parts of soybean protein powder, 68-72 parts of water, 5-8 parts of a cross-linking agent and 0.5-1 part of a hybridization agent.

7. The soy protein adhesive of claim 6, comprising, in parts by weight: 30 parts of soybean protein powder, 70 parts of water, 6 parts of a cross-linking agent and 1 part of a hybridization agent.

8. A method of preparing the soy protein adhesive of any of claims 1-7, comprising the steps of preparing the cross-linking agent;

the preparation method of the cross-linking agent comprises the following steps:

mixing DHBA and TBSCl to obtain 3, 4-dihydroxybenzoic acid DHBAT for protecting catechol group, and dissolving starch in CH₂Cl₂Cooling to 0 ℃, adding DHBAT and catalyst DMAP, stirring uniformly, then adding catalyst DCC, stirring uniformly at room temperature, adding TBAF, stirring and heating to 48-52 ℃.

9. The method of claim 8, comprising:

1) uniformly mixing the soybean protein powder with a calcium chloride aqueous solution;

2) adding the cross-linking agent, stirring and mixing uniformly, and adding carbonic acid.

10. Use of the soy protein adhesive of any one of claims 1 to 7 or the soy protein adhesive prepared by the process of claim 8 or 9 for the preparation of plywood.

Technical Field

The invention relates to the technical field of biomass adhesives, in particular to a soy protein adhesive and a preparation method and application thereof.

Background

Precious wood resources are relatively deficient, artificial forest resources are rich, artificial boards prepared from fast growing woods of the artificial forests through adhesives are main raw materials for furniture floors and indoor decoration in human living environments, the total yield of the artificial boards is large, and most of the artificial boards are plywood products. The consumption of the adhesive for the plywood is huge (the solid content is 50%) according to the average production of 9 cubic meters of artificial boards by each ton of the adhesive, wherein the urea-formaldehyde resin and modified products thereof occupy the dominant position of the adhesive. The urea-formaldehyde resin adhesive is widely used in the wood industry due to the advantages of sufficient raw materials, low price, good water solubility and the like, but has the problem of formaldehyde release of products. With the improvement of living standard of people, people pay attention to the problem of environmental pollution. The artificial board prepared by the biomass adhesive can solve the problem of free formaldehyde emission of the artificial board, and is an important way for solving the problem, but most biomass adhesives have the problems of poor water-resistant bonding performance, poor flame retardance and the like, so that the industrial application of the biomass adhesives is limited.

Therefore, it is necessary to provide a novel soy protein adhesive, a preparation method and an application thereof to solve the problems in the prior art.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide the soybean protein adhesive which has the advantages of good bonding strength, good prepressing performance, good flame retardant property and mild heat treatment conditions during processing.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a soy protein adhesive comprises soy protein powder, water, a cross-linking agent and a hybridization agent; the cross-linking agent is a catechol polysaccharide cross-linking agent prepared by the reaction of starch and 3, 4-dihydroxy benzoic acid; the hybridization agent is calcium carbonate generated in situ.

The soybean protein powder is low-temperature protein powder with 90% of protein content and 200 meshes of average particle size.

The cross-linking agent adopts starch as a raw material, and introduces catechol groups to the main chain of polysaccharide through esterification reaction catalyzed by 4-dimethylamino-pyridine (DMAP) and/or N, N-dicyclohexyl carbodiimide (DCC) to prepare the catechol polysaccharide cross-linking agent with a specific structure. According to the invention, the specific catechol polysaccharide cross-linking agent and the protein, polysaccharide and fiber in the soybean protein raw material form chemical bonds and strong hydrogen bonds to be connected by utilizing the long-chain flexible structure rich in the catechol structure to form an integrated specific flexible cross-linking structure, and the polysaccharide cross-linking agent and the calcium carbonate formed in situ can form a specific organic-inorganic hybrid system, so that the water resistance, the adhesion and the flame retardance of the adhesive can be improved. Compared with the traditional epoxy crosslinking agent, the special structure and the multifunctional functional group of the invention can lead the thermal processing condition to be milder, the curing time to be shorter, the bonding strength to be higher and the flame retardant property to be provided when the plywood is manufactured subsequently, and are suitable for the actual industrial utilization. Therefore, the invention successfully replaces the traditional petroleum-based epoxy cross-linking agent, so that the main components of protein, polysaccharide, fiber and the like in the soybean protein react with the cross-linking agent to form a branched cross-linked network hybrid structure.

In the present invention, the starch is preferably corn starch.

In the invention, the mass ratio of the starch to the 3, 4-dihydroxy benzoic acid is 1 (0.8-1.2).

Preferably, the mass ratio of the starch to the 3, 4-dihydroxybenzoic acid is 1: 1.2.

In the invention, the mass ratio of the cross-linking agent to the soybean protein powder is 1: (5-7).

The mass ratio of the soybean protein powder to the hybridization agent is 30: (0.5-1).

Preferably, the mass ratio of the cross-linking agent to the soybean protein powder is 1: 5; the mass ratio of the soybean protein powder to the hybridization agent is 30: 1 to achieve a more desirable overall effect.

The soy protein adhesive comprises the following components in parts by weight: 28-30 parts of soybean protein powder, 68-72 parts of water, 5-8 parts of a cross-linking agent and 0.5-1 part of a hybridization agent.

Preferably, the composition comprises the following components in parts by weight: 30 parts of soybean protein powder, 70 parts of water, 6 parts of a cross-linking agent and 1 part of a hybridization agent.

The components of the invention are matched according to reasonable dosage, the matching effect of the components can be fully exerted, the effect can be ensured, and the cost can be saved.

The water in the invention can be ordinary tap water or softened water.

The invention also discloses a method for preparing the soybean protein adhesive, which comprises the step of preparing the cross-linking agent;

the preparation method of the cross-linking agent comprises the following steps:

mixing 3, 4-dihydroxybenzoic acid (DHBA) with dimethyl-tert-butylchlorosilane (TBSCl) to obtain 3, 4-dihydroxybenzoic acid (DHBAT) with protected catechol group, and dissolving starch in CH₂Cl₂Cooling to 0 ℃, adding DHBAT and catalyst DMAP, stirring uniformly, then adding catalyst DCC, stirring uniformly at room temperature, adding TBAF (for removing protective group), stirring and heating to 48-52 ℃.

Specifically, DHBA was prepared by mixing DHBA and TBSCl at a molar ratio of 1:2 for 10 minutes.

The amount of starch and DHBAT added to ensure that the final product meets the above defined ratio relationship between starch and DHBA. Other catalysts and deprotection agents are added in an amount to ensure that the reaction is fully performed.

As a specific embodiment, the mass ratio of starch to N, N-Dicyclohexylcarbodiimide (DCC), 4-dimethylamino-pyridine (DMAP), tetrabutylammonium fluoride (TBAF) is: 2: (5-7): 0.14: (5-7).

According to the cross-linking agent, the raw materials can obtain an ideal cross-linked hybrid structure in the proportion, and the cross-linking agent is favorable for forming a compact and uniform cross-linked network structure with the soybean protein powder subsequently, so that the overall performance of the adhesive is improved. The proportion of the amount of each catalyst and the amount of the deprotection agent can be helpful for preparing the specific crosslinking agent.

The method comprises the following steps:

1) uniformly mixing the soybean protein powder with a calcium chloride aqueous solution;

2) adding the cross-linking agent, stirring and mixing uniformly, and adding carbonic acid.

The preparation method is beneficial to guarantee the final effect of the product.

The invention also provides an application of the soybean protein adhesive or the soybean protein adhesive prepared by the method in preparing plywood.

When in application, the processing condition is mild, the curing is fast, and the industrial application is facilitated.

The invention has the beneficial effects that:

1) the water-soluble catechol polysaccharide and the soybean protein powder have crosslinking reaction or strong hydrogen bond combination, the system compatibility is good, a specific multiple network structure can be formed, and the adhesive toughness is improved while the crosslinking density of the adhesive is improved. After the catechol polysaccharide is added, the adhesive can form stable hydrogen bond connection with the surface of wood before curing, so that the prepressing performance and the coating performance of the adhesive are greatly improved.

2) According to the invention, calcium carbonate formed in situ is utilized to form strong hybridization with catechol polysaccharide, so that the cohesive force and the flame retardance of the adhesive are improved. And the calcium carbonate formed in the protein system has uniform granularity and good form, and is beneficial to hybridization enhancement and system stability.

3) The cross-linking agent disclosed by the invention is simple and efficient in synthesis process, can be compatible with soybean protein powder and other components, is shorter in curing time (can be subjected to chemical reaction at a lower temperature) at the same reaction temperature, successfully constructs a specific hyperbranched cross-linked network structure in a soybean protein adhesive system, and improves the water-resistant adhesive bonding performance of the adhesive.

5) The soybean protein adhesive disclosed by the invention is free of toxic substances, high in synthesis efficiency, free of harmful substance release, high in product reaction activity, good in manufacturability, stable in performance of each batch, low in cost and beneficial to industrial application.

The test proves that: the adhesive disclosed by the invention is easy to form a specific crosslinking structure, high in crosslinking density, short in curing time (low in reaction temperature), excellent in flame retardant property and good in manufacturability, the prepared adhesive is stable in performance, a weak interface layer is obviously reduced, the cost is reduced, the water-resistant bonding performance is good, and the product quality is stable. The water-resistant and technological requirements of the plywood adhesive can be met, and the practical performance of the biomass adhesive is ensured.

Detailed Description

Preferred embodiments of the present invention will be described in detail with reference to the following examples. It is to be understood that the following examples are given for illustrative purposes only and are not intended to limit the scope of the present invention. Various modifications and alterations of this invention will become apparent to those skilled in the art without departing from the spirit and scope of this invention.

The experimental procedures used in the following examples are all conventional procedures unless otherwise specified. Materials, reagents and the like used in the following examples are commercially available unless otherwise specified.

In the present invention, the term "%" refers to mass% unless otherwise specified; but the percentage of the solution, unless otherwise specified, means that 100ml of the solution contains several grams of solute; the percentage between the liquids refers to the ratio of the volumes at 20 ℃.

The soybean meal used in the embodiment of the invention has the protein content of 90 percent and the particle size of 200 meshes, and is purchased from Shandong Yuwang ecological food industry Co.

Example 1

The embodiment provides the adhesive and the preparation method thereof.

The specific formula comprises the following components in parts by weight:

30 parts of soybean protein powder, 70 parts of water, 6 parts of a cross-linking agent and 1 part of a hybridization agent (calcium carbonate).

The cross-linking agent is a catechol polysaccharide cross-linking agent, and the preparation process comprises the following steps:

preparing DHBAT: DHBA and TBSC1 were mixed and stirred at a molar ratio of 1:2 for 10 minutes to prepare DHBAT having a catechol group protected.

2g corn starch was added to 30mL CH₂Cl₂Neutralizing and stirring at room temperature until completely dissolved and cooling to 0 deg.C, adding corresponding amount of DHBAT and 0.14g DMAP based on the mass ratio of corn starch to DHBA in the final crosslinking agent of 1:1.2, and stirring the solution at the temperature for 10min. Then 6g of DCC was added to the solution and the reaction mixture was warmed to room temperature and stirred for 24 hours. After stirring was complete 6.22g of TBAF were added to the solution, the mixture was stirred at room temperature for 1 hour, after stirring was complete the temperature was raised to 50 ℃ and excess CH was removed₂Cl₂Evaporating to remove the catechol polysaccharide cross-linking agent.

The preparation method of the viscose agent comprises the following steps:

weighing the components according to a formula, firstly adding 30g of soybean protein powder into a solution containing 0.01mol of calcium chloride and 70g of water, stirring for 5min to mix uniformly, then adding 6g of the catechol polysaccharide crosslinking agent prepared in the above step into the mixed solution, stirring uniformly at room temperature for 10min at the rotating speed of 1200r/min to disperse the crosslinking agent in the solution uniformly, adding 0.01mol of carbonic acid, and stirring for 10min to obtain the adhesive.

Example 2

The embodiment provides the adhesive and the preparation method thereof. The preparation method is the same as that of the example 1, and the difference is that the formula comprises the following components in parts by weight: 28 parts of soybean protein powder, 68 parts of water, 5 parts of a cross-linking agent and 0.5 part of a hybridization agent (calcium carbonate).

Example 3

The embodiment provides the adhesive and the preparation method thereof. The formula and the preparation method are the same as those of example 1, and the difference is only that when the cross-linking agent is prepared, the addition amount of DHBAT is changed, so that the mass ratio of the corn starch to the DHBA in the final cross-linking agent is 1: 0.8.

comparative example 1

This comparative example provides an adhesive that is the same as the formulation and method of preparation of example 1, except that, in preparing the cross-linker, the amount of DHBAT added was changed so that the mass ratio of corn starch to DHBA in the final cross-linker was 1: 0.6.

comparative example 2

This comparative example provides an adhesive and a method of making the same. It is the same as the formulation of example 1, except that no crosslinking agent and no hybridization agent are added. During preparation, only water and soy protein powder are mixed to prepare the adhesive.

Comparative example 3

This comparative example provides an adhesive and a method of making the same. It is the same as the formulation of example 1, except that no hybridization agent is added. During preparation, the soybean protein powder is added into water to be uniformly mixed, then the catechol polysaccharide cross-linking agent is added into the mixed solution, and the mixed solution is uniformly stirred at room temperature for 10min at the rotating speed of 1200r/min, so that the cross-linking agent is uniformly dispersed in the solution to prepare the adhesive.

Comparative example 4

This comparative example provides an adhesive and a method of making the same. It is the same as the formulation of example 1, except that no crosslinker is added. During preparation, the soybean protein powder is added into the calcium chloride aqueous solution, stirred for 5min to be uniformly mixed, added with carbonic acid and stirred for 10min to prepare the adhesive.

Comparative example 5

This comparative example provides an adhesive and a method of making the same. It is the same as the formulation of example 1 except that the cross-linking agent is replaced by normal corn starch. During preparation, adding corn starch into a calcium chloride aqueous solution, stirring for 5min to uniformly mix, adding the corn starch into the mixed solution, uniformly stirring at room temperature for 10min at the rotating speed of 1200r/min to uniformly disperse the cross-linking agent in the solution, adding carbonic acid, and stirring for 10min to obtain the adhesive.

Comparative example 6

This comparative example is a conventional E0 grade urea formaldehyde resin adhesive (available from Qiansheng, Inc. of Shandong).

Comparative example 7

This comparative example provides an adhesive and a method of making the same. It is the same as the formulation and preparation method of example 1 except that the crosslinking agent is tannic acid instead of the catechol-based polysaccharide crosslinking agent of example 1.

Experimental example 1

The adhesives obtained in the above examples and comparative examples were tested in this experimental example.

Specifically, three-layer plywood was prepared from the adhesives obtained in the above examples and comparative examples to test the adhesive strength.

Poplar veneer: drying to 10% of water content; size 40cm by 0.15 cm.

The preparation method comprises the following normal preparation processes:

sizing: the glue coating amount is 360g/m²。

Hot pressing conditions are as follows: the pressure is 0.8MPa, the temperature is 110 ℃, and the time is 8 minutes.

The performance of the cross-spliced wood products is tested according to the method for testing the performance of the cross-spliced wood products in GB/T17657-1999 experiment methods for physical and chemical properties of artificial boards and veneered artificial boards, the measurement of all the plywood samples is repeated for six times, the average value is obtained, and the detection results are shown in Table 1.

TABLE 1

Although the invention has been described in detail hereinabove with respect to a general description and specific embodiments thereof, it will be apparent to those skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.