PLANT PROTEIN-FURFURYL ALCOHOL WOOD ADHESIVE AND PREPARATION METHOD THEREOF

Abstract

A plant protein-furfuryl alcohol wood adhesive and a preparation method thereof are disclosed. The adhesive according to the disclosure is prepared from raw materials comprising, in parts by weight, 10 to 15 parts of a plant protein, 10 to 25 parts of furfuryl alcohol, 4 to 8 parts of water, 1 to 6 parts of a catalyst, and 0 to 20 parts of an additive.

Claims

1. A plant protein-furfuryl alcohol wood adhesive, which is prepared from raw materials comprising, in parts by weight, 10 to 15 parts of a plant protein, 10 to 25 parts of furfuryl alcohol, 4 to 8 parts of water, 1 to 6 parts of a catalyst, and 0 to 20 parts of an additive.

2. The plant protein-furfuryl alcohol wood adhesive of claim 1, wherein the plant protein is selected from the group consisting of hydrolyzed wheat protein, hydrolyzed soybean protein, and hydrolyzed Jatropha curcas protein, wherein the plant protein has a protein content of 70%-90%, and a total content of starch content and sugar content of 4%-8%.

3. The plant protein-furfuryl alcohol wood adhesive of claim 1, wherein the catalyst is an acid catalyst.

4. The plant protein-furfuryl alcohol wood adhesive of claim 3, wherein the acid catalyst is selected from the group consisting of p-toluenesulfonic acid, hydrochloric acid, 2-chloroacetic acid, 2-bromoacetic acid, and nitrous acid.

5. The plant protein-furfuryl alcohol wood adhesive of claim 1, wherein the additive is one or more selected from the group consisting of glyoxal, formaldehyde, glutaraldehyde, and furfural.

6. A method for preparing the plant protein-furfuryl alcohol wood adhesive of claim 1 for thermal curing, the method comprising: (1) stirring the plant protein, the furfuryl alcohol, and the water at ambient temperature for 5-10 minutes to be uniform, thereby obtaining a mixture; and (2) adding the catalyst into the mixture, and stirring to be uniform, thereby obtaining the plant protein-furfuryl alcohol wood adhesive, wherein the plant protein-furfuryl alcohol wood adhesive is applicable for the preparation of a hot-pressed plywood.

7. The method of claim 6, wherein the plant protein is selected from the group consisting of hydrolyzed wheat protein, hydrolyzed soybean protein, and hydrolyzed Jatropha curcas protein, wherein the plant protein has a protein content of 70%-90%, and a total content of starch content and sugar content of 4%-8%.

8. The method of claim 6, wherein the catalyst is an acid catalyst.

9. The method of claim 8, wherein the acid catalyst is selected from the group consisting of p-toluenesulfonic acid, hydrochloric acid, 2-chloroacetic acid, 2-bromoacetic acid, and nitrous acid.

10. A method for preparing the plant protein-furfuryl alcohol wood adhesive of claim 1 for cold-pressing curing, the method comprising: (1) stirring the plant protein, the furfuryl alcohol, and the water at ambient temperature for 5-10 minutes to be uniform, thereby obtaining a mixture; and (2) adding the catalyst and the additive into the mixture, and stirring to be uniform, thereby obtaining the plant protein-furfuryl alcohol wood adhesive.

11. The method of claim 10, wherein the plant protein is selected from the group consisting of hydrolyzed wheat protein, hydrolyzed soybean protein, and hydrolyzed Jatropha curcas protein, wherein the plant protein has a protein content of 70%-90%, and a total content of starch content and sugar content of 4%-8%.

12. The method of claim 10, wherein the catalyst is an acid catalyst.

13. The method of claim 12, wherein the acid catalyst is selected from the group consisting of p-toluenesulfonic acid, hydrochloric acid, 2-chloroacetic acid, 2-bromoacetic acid, and nitrous acid.

14. The method of claim 10, wherein the additive is one or more selected from the group consisting of glyoxal, formaldehyde, glutaraldehyde, and furfural.

Description

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The specific embodiments of the present disclosure will be described in further detail below, but the present disclosure is not limited to these embodiments. Any improvement or substitution in the basic spirit of the embodiment still falls within the scope claimed by the claims of the present disclosure.

Hot Pressing

Example 1 (Thermal Curing)

[0027] 12 parts of hydrolyzed wheat protein, 10 parts of furfuryl alcohol and 6 parts of water were stirred at ambient temperature for 5-10 minutes to be uniform, obtaining a mixture. 3 parts of a p-toluenesulfonic acid solution (with a concentration of 65%) was added into the mixture and stirred to be uniform, obtaining an adhesive. The adhesive was evenly spread on the upper and lower surfaces of the core layer of a poplar wood veneer, with a double-sided spreading amount of the adhesive being 260 g/m.sup.2, to prepare a three-layer plywood. The three-layer plywood was subjected to a hot pressing according to a plywood hot pressing process at a temperature of 180° C. and a unit pressure of 1.5 MPa for 7 min.

Example 2 (Thermal Curing)

[0028] 12 parts of hydrolyzed wheat protein, 10 parts of furfuryl alcohol and 6 parts of water were stirred at ambient temperature for 5-10 minutes to be uniform, obtaining a mixture. 3 parts of a p-toluenesulfonic acid solution (with a concentration of 65%) was added into the mixture and stirred to be uniform, obtaining an adhesive. The adhesive was evenly spread on the upper and lower surfaces of the core layer of a poplar wood veneer, with a double-sided spreading amount of the adhesive being 240 g/m.sup.2, to prepare a three-layer plywood. The three-layer plywood was subjected to a hot pressing according to a plywood hot pressing process at a temperature of 140° C. and a unit pressure of 1.5 MPa for 6 min.

Example 3 (Thermal Curing)

[0029] 12 parts of hydrolyzed wheat protein, 10 parts of furfuryl alcohol and 6 parts of water were stirred at ambient temperature for 5-10 minutes to be uniform, obtaining a mixture. 2 parts of a p-toluenesulfonic acid solution (with a concentration of 65%) was added into the mixture and stirred to be uniform, obtaining an adhesive. The adhesive was evenly spread on the upper and lower surfaces of the core layer of a poplar wood veneer, with a double-sided spreading amount of the adhesive being 240 g/m.sup.2, to prepare a three-layer plywood. The three-layer plywood was subjected to a hot pressing according to a plywood hot pressing process at a temperature of 180° C. and a unit pressure of 1.5 MPa for 6 min.

Example 4 (Thermal Curing)

[0030] 12 parts of hydrolyzed soybean protein, 10 parts of furfuryl alcohol and 6 parts of water were stirred at ambient temperature for 5-10 minutes to be uniform, obtaining a mixture. 3 parts of a p-toluenesulfonic acid solution (with a concentration of 65%) was added into the mixture and stirred to be uniform, obtaining an adhesive. The adhesive was evenly spread on the upper and lower surfaces of the core layer of a poplar wood veneer, with a double-sided spreading amount of the adhesive being 260 g/m.sup.2, to prepare a three-layer plywood. The three-layer plywood was subjected to a hot pressing according to a plywood hot pressing process at a temperature of 180° C. and a unit pressure of 1.5 MPa for 7 min.

Example 5 (Thermal Curing)

[0031] 12 parts of hydrolyzed Jatropha curcas protein, 10 parts of furfuryl alcohol and 6 parts of water were stirred at ambient temperature for 5-10 minutes to be uniform, obtaining a mixture. 3 parts of a hydrochloric acid aqueous solution (with a concentration of 10%) was added into the mixture and stirred to be uniform, obtaining an adhesive. The adhesive was evenly spread on the upper and lower surfaces of the core layer of a poplar wood veneer, with a double-sided spreading amount of the adhesive being 260 g/m.sup.2, to prepare a three-layer plywood. The three-layer plywood was subjected to a hot pressing according to a plywood heat pressing process at a temperature of 180° C. and a unit pressure of 1.5 MPa for 7 min.

Comparative Example 1 (Thermal Curing)

[0032] 10 parts of furfuryl alcohol and 6 parts of water were stirred at ambient temperature for 5-10 minutes to be uniform, obtaining a mixture. 2 parts of p-toluenesulfonic acid solution (with a concentration of 65%) was added in the mixture and stirred to be uniform, obtaining an adhesive. The adhesive was evenly spread on the upper and lower surfaces of the core layer of a poplar wood veneer, with a double-sided spreading amount of the adhesive being 240 g/m.sup.2, to prepare a three-layer plywood. The three-layer plywood was subjected to a hot pressing according to a plywood heat pressing process at a temperature of 180° C. and a unit pressure of 1.5 MPa for 6 min.

Comparative Example 2 (Thermal Curing)

[0033] 12 parts of hydrolyzed wheat protein and 6 parts of water were stirred at ambient temperature. In the actual operation process, the operation is difficult due to a high viscosity, which makes it difficult to achieve its uniformity. 2 parts of p-toluenesulfonic acid solution (with a concentration of 65%) was added thereto, and stirred as much as possible. The prepared adhesive was evenly spread on the upper and lower surfaces of the core layer of a poplar wood veneer, with a double-sided spreading amount of the adhesive being 240 g/m.sup.2 to prepare a three-layer plywood. The three-layer plywood was subjected to a hot pressing according to a plywood hot pressing process at a temperature of 180° C. and a unit pressure of 1.5 MPa for 6 min.

Cold Pressing

Example 6 (Cold Curing)

[0034] 12 parts of hydrolyzed wheat protein, 24 parts of furfuryl alcohol and 8 parts of water were stirred at ambient temperature for 5-10 minutes to be uniform, obtaining a mixture. 6 parts of p-toluenesulfonic acid solution (with a concentration of 65%) was added into the mixture, and stirred to be uniform, obtaining an adhesive for later use. Before spreading, 16 parts of a glyoxal solution with a concentration of 40% was added to the adhesive. The final prepared adhesive was evenly spread on two surfaces of a rubber wood, with a double-sided spreading amount of the adhesive being 240 g/m.sup.2 to prepare a glulam sample. The glulam sample was then subjected to a cold pressing according to a cold pressing process at a unit pressure of 1.5 MPa for 6 h.

Example 7 (Cold Curing)

[0035] 12 parts of hydrolyzed soybean protein, 24 parts of furfuryl alcohol and 8 parts of water were stirred at ambient temperature for 5-10 minutes to be uniform, obtaining a mixture. 4 parts of a hydrochloric acid aqueous solution (with a concentration of 10%) was added thereto, and stirred to be uniform, obtaining an adhesive for later use. Before spreading, 10 parts of glutaraldehyde solution with a concentration of 50% was added to the adhesive. The final prepared adhesive was evenly spread on two surfaces of a rubber wood with a double-sided spreading amount of the adhesive being 240 g/m.sup.2, obtaining a glulam sample. The glulam sample was then subjected to a cold pressing according to the cold pressing process at ambient temperature and a unit pressure of 1.5 MPa for 6 h.

Comparative Example 3 (Cold Curing)

[0036] 12 parts of hydrolyzed wheat protein, 24 parts of furfuryl alcohol and 8 parts of water were stirred at ambient temperature for 5-10 minutes to be uniform, obtaining a mixture. 6 parts of p-toluenesulfonic acid solution (with a concentration of 65%) was added into the mixture, and stirred to be uniform, obtaining an adhesive for later use. Without adding any additives, the adhesive was directly evenly spread on two surfaces of a rubber wood, with a double-sided spreading amount of the adhesive being 240 g/m.sup.2 to prepare a glulam sample. The glulam sample was subjected to a cold pressing according to a cold pressing process at a unit pressure of 1.5 MPa for 6 h.

[0037] The hot pressed plywoods and cold pressed glulams obtained in all the examples and comparative examples were subjected to a shear strength test, respectively. The results of the shear strength test for the hot pressed plywoods are shown in Table 1, and the results of the shear strength for the cold pressed glulams are shown in Table 2.

TABLE-US-00001 TABLE 1 Shear strength Shear strength Shear strength (cold water, (63° C., (boiling water, Examples 24 h)/MPa 3 h)/MPa 3 h)/MPa Example 1 1.02 1.00 1.42 Example 2 0.46 — — Example 3 0.54 0.67 0.46 Example 4 1.00 0.97 0.95 Example 5 0.95 0.87 0.87 Comparative — — — Example 1 Comparative — — — Example 2 Notes: “—” means that the sample has been degummed and failed during the soaking process.

[0038] It can be seen from Table 1 that the effect difference between Examples 1 and 2 is due to the great influence of a plywood hot pressing process on the performance of the panel. Through additional orthogonal experiments, it is concluded that the spreading amount of adhesives and the hot pressing temperature have a greater impact on the performance of the panel. The product of Example 1 has a high shear strength, and still has bonding strength far beyond the requirements of the standards after soaking in boiling water for 3 hours. It can be seen from Example 3 that the addition of pTSA (i.e., the pH) has a significant effect on the curing of the adhesive, and the reduction of the amount of acid leads to an uncomplete crosslinking of the adhesive, thereby resulting in a substandard shear strength. It can be determined from Examples 4 and 5 that all plywoods prepared from different plant proteins and adhesives synthesized in the presence of different acids have performance meeting the requirements of China's standards. Both the plywoods prepared by the separately prepared furfuryl alcohol adhesive (Comparative Example 1) and wheat protein adhesive (Comparative Example 2) have performance not meeting the China's standards, and are generally degummed and failed during the soaking process.

TABLE-US-00002 TABLE 2 Shear strength Shear strength (dry condition)/ (63° C., Examples MPa 3 h)/MPa Example 6  7.25  6.80 Example 7  6.57  6.52 Comparative 1.2 1.8 Example 3

[0039] It can be seen from Examples 6 and 7, whether hydrolyzed wheat protein or hydrolyzed soybean protein is used, the adhesive prepared with glyoxal or glutaraldehyde as the crosslinking agent has a good cold pressing effect, and the glulam has a strength meeting the requirements of the standards. It can be seen from the results of the Comparative Example 3, without the addition of an additive, the adhesive has a poor cold pressing effect on the panel, and the panel has a bonding strength not meeting the requirements of the standards.