CN115926730A - Supermolecule wood adhesive and application thereof - Google Patents

Abstract

The invention provides a supermolecule wood adhesive which is prepared from folic acid and a polyamino cationic polymer serving as raw materials in a water solvent. The raw materials are biologically friendly, green and nontoxic, the source is wide, reaction auxiliaries and organic reagents are not needed, the reaction condition is mild, special conditions and equipment are not needed, and the preparation method is simple, green and environment-friendly. The prepared supermolecule wood adhesive has excellent adhesive capacity and mechanical property, can greatly improve the adhesive strength of wood materials, has lasting adhesion, can meet the requirements of industrial production and use, and is beneficial to popularization, production and application.

Description

Supermolecule wood adhesive and application thereof

Technical Field

The invention belongs to the technical field of adhesives, particularly relates to a supramolecular adhesive, and particularly relates to a supramolecular green adhesive for bonding wood materials.

Background

At present, adhesives used for wood in the market are mainly 'three-aldehyde adhesives', namely formaldehyde adhesives such as urea formaldehyde, phenol formaldehyde, melamine-formaldehyde and the like. These adhesives synthesized from formaldehyde and fossil raw materials release harmful substances such as free formaldehyde during the production and application of the board. Formaldehyde is a colorless, strongly irritating gas that has been identified by the world health organization as a carcinogenic and teratogenic substance. Chronic respiratory diseases can be caused by long-term exposure to low-dose formaldehyde, and serious health problems such as nasopharyngeal carcinoma, brain tumor, pregnancy syndrome, neonatal chromosome abnormality, leukemia and the like are caused.

Researches show that the indoor formaldehyde pollution mainly comes from formaldehyde-based adhesives and coatings used for furniture, decoration and the like, and the release period of formaldehyde contained in the indoor formaldehyde pollution is as long as 3-15 years, thus seriously affecting the healthy life of people. In addition, in view of the increasing shortage of petroleum resources and from the viewpoint of human health, the search for renewable wood adhesives with low emissions or complete absence of formaldehyde has been receiving high attention.

A plurality of green and environment-friendly novel wood adhesives are designed and developed by taking natural renewable substances as raw materials, such as vegetable oil, starch, cellulose, protein, lignin, tannin and the like and derivatives thereof as raw material sources of the adhesives. However, there are problems with these current biomass-based adhesives. For example, lignin is not chemically reactive and therefore requires higher hot pressing temperatures and curing times; in addition, most lignin adhesives require a small amount of aldehyde components as a crosslinking agent to improve the mechanical strength of the adhesive. Starch-based and animal protein-based adhesives often have a problem of weak adhesive strength, and researchers have also devised some supramolecular polymer adhesives of crown ethers or thiocinol, ionic crystals, and the like. However, these adhesives require complicated molecular design or means such as heating and ultraviolet excitation.

Therefore, it is still challenging to develop a bio-based wood adhesive material that is formaldehyde-free, simple in preparation method, and has strong adhesion and durable adhesion ability.

Disclosure of Invention

In order to solve the problems, the invention provides a green environment-friendly wood adhesive which is prepared by supermolecule assembly by using folic acid and a polyamino cationic polymer as raw materials. The adhesive is prepared in a water system, harmful substances such as synthetic auxiliary agents, organic reagents and the like are not needed in the preparation process, the process is simple, and the obtained adhesive is strong in bonding force, good in mechanical property and high in non-toxic safety performance. In the wood bonding aspect, the adhesive has the advantages of safety and no toxicity, can be well combined with a wood bonding substrate, and realizes high-strength and durable adhesion, thereby completing the invention.

The invention aims to provide a supramolecular wood adhesive which is prepared from raw materials comprising folic acid and a polyamino cationic polymer. Preferably, the adhesive is prepared in an aqueous solvent.

The polyamine-based cationic polymer comprises one or more of primary amine groups, secondary amine groups, tertiary amine groups and quaternary amine groups, preferably comprises two or three of primary amine groups, secondary amine groups, tertiary amine groups and quaternary amine groups, and more preferably comprises the primary amine groups, the secondary amine groups and the tertiary amine groups at the same time.

The invention also aims to provide a preparation method of the supramolecular wood adhesive, raw materials for preparing the supramolecular wood adhesive comprise folic acid and multi-amino cationic polymer, and the raw materials are dispersed in an aqueous solution for preparation.

The invention also aims to provide the application of the supermolecule wood adhesive, which is used for adhering wood materials, wherein the shear adhesion strength is higher than 1.5MPa after 4 hours of bonding, and the shear adhesion strength is higher than 3.6MPa after 7 hours of bonding.

The supramolecular wood adhesive is prepared from raw materials including folic acid and a poly-amino cationic polymer, preferably, the adhesive is prepared in an aqueous solvent.

The polyamine-based cationic polymer comprises one or more of primary amine groups, secondary amine groups, tertiary amine groups and quaternary amine groups, preferably comprises two or three of primary amine groups, secondary amine groups, tertiary amine groups and quaternary amine groups, and more preferably comprises the primary amine groups, the secondary amine groups and the tertiary amine groups at the same time.

The weight average molecular weight of the polyamino cationic polymer is from 70,000 to 700,000, preferably from 80,000 to 450,000, more preferably from 90,000 to 150,000.

The supramolecular wood adhesive is prepared by dispersing a raw material comprising folic acid and a poly-amino cationic polymer in an aqueous solution, and specifically comprises the following steps:

step 1, dissolving folic acid in water to obtain folic acid solution;

step 2, dissolving the polyamine-based cationic polymer in water to obtain a solution II;

and 3, mixing and stirring the folic acid solution and the solution II, and separating to obtain the supramolecular wood adhesive.

The supramolecular wood adhesive and the application thereof provided by the invention have the following beneficial effects:

(1) The invention uses folic acid and multi-amino cationic polymer, especially branched polyethyleneimine as raw materials to prepare the supermolecule wood adhesive, which can be used for bonding various woods and has strong bonding force and good mechanical property.

(2) The supramolecular wood adhesive disclosed by the invention is a bio-based aldehyde-free adhesive, does not contain harmful substances such as formaldehyde and other organic reagents, is a green, environment-friendly and healthy adhesive, is particularly suitable for wood production of indoor furniture, and does not release toxic and harmful substances in the production and furniture use processes, so that a healthy living environment is realized, and the environmental pollution is reduced.

(3) The supermolecule wood adhesive is used for bonding wood materials, and after the supermolecule wood adhesive is cured for 7 hours, the shearing adhesion strength can reach more than 3.65MPa, and is more than 1.4 times, even more than 14 times of the shearing adhesion strength of the adhesive on the market. The adhesive is completely nontoxic, environment-friendly and bio-friendly.

(4) The preparation process of the supramolecular adhesive material does not need harsh preparation conditions and special equipment, has wide material sources and low production cost, is beneficial to large-scale production, has simple and convenient use method, and is utilized, popularized and applied.

Drawings

FIG. 1 shows the IR spectrum of the folic acid-bPEI supramolecular wood adhesive FA-bPEI-9, folic acid (FA-9) and branched polyethyleneimine (b-PEI) prepared in example 1 of the invention;

FIG. 2 shows SEM pictures obtained from tests on FA-bPEI-9 prepared in example 1 of the present invention after lyophilization;

FIG. 3 shows the high resolution mass spectrum of the folic acid-bPEI supramolecular wood adhesive FA-bPEI-9 prepared in example 1 of the invention;

FIG. 4 shows an XRD pattern of a folic acid-bPEI supramolecular wood adhesive FA-bPEI-9 prepared in example 1 of the invention;

FIG. 5 shows the trend of loss modulus G 'and storage modulus G' of folic acid-bPEI supramolecular wood adhesives FA-bPEI-9, FA-bPEI-10 and FA-bPEI-11 prepared in example 1 of the invention;

FIG. 6 is a graph showing the fracture positions of a tung wood specimen in the shear adhesion strength test in Experimental example 5 of the present invention;

FIG. 7 (a) is an SEM image showing that folic acid-bPEI supramolecular wood adhesive FA-bPEI-9 prepared in example 1 of the invention adheres to two tung wood chip faults; FIG. 7 (b) is a schematic diagram showing the mechanical interlocking of the supramolecular wood adhesive penetrating into the wood chips and curing in the present invention;

FIG. 8 shows the IR spectra of the folic acid-bPEI supramolecular wood adhesive FA-bPEI-9 powder, FA-bPEI-9 and lignin mixture and lignin prepared in example 1 of the present invention;

FIG. 9 shows the IR spectra of FA-bPEI-9 powder, FA-bPEI-9 mixed with cellulose and cellulose prepared by the present invention in example 1.

Detailed Description

The present invention will be described in detail below with reference to specific embodiments, and features and advantages of the present invention will become more apparent and apparent with reference to the description.

The invention provides a green environment-friendly wood adhesive material prepared by supermolecule assembly by taking folic acid and a multi-amino cationic polymer as raw materials, which is prepared by adopting a water system, wherein the raw materials are green raw materials, the process is simple, the obtained adhesive material has strong binding power and good mechanical property, and is non-toxic, high in safety performance and good in biocompatibility. The adhesive has wide application prospect in industrial adhesives, particularly has the advantages of safety and no toxicity in the aspect of wood bonding, and can be well combined with a wood bonding substrate so as to obtain super-strong bonding force.

The invention provides a supramolecular wood adhesive which is prepared from raw materials comprising folic acid and a poly-amino cationic polymer, preferably the adhesive is prepared in an aqueous solvent. The water solvent is industrial water, distilled water, deionized water or ultrapure water, preferably distilled water, deionized water or ultrapure water, and more preferably ultrapure water.

Folic acid, also known as pteroylglutamic acid, is a naturally abundant vitamin B group that can be extracted from various natural foods, such as green vegetables, beans, and fruits. Meanwhile, the product is a yellowish crystalline powder with stable thermodynamics and low cost.

Folic acid carries carboxyl, carbonyl and amide groups, and can realize metal complexation and electrostatic interaction with other components. In the invention, folic acid is used as a raw material for preparing the supermolecule wood adhesive, and has wide sources and low price. Folic acid has not been used in the field of adhesives to date.

The polyamine-based cationic polymer comprises one or more of primary amine groups, secondary amine groups, tertiary amine groups and quaternary amine groups, preferably comprises two or three of primary amine groups, secondary amine groups, tertiary amine groups and quaternary amine groups, and more preferably comprises the primary amine groups, the secondary amine groups and the tertiary amine groups at the same time.

Preferably, the polyamine-based cationic polymer is selected from one or more of branched polyethyleneimine, branched polypropyleneimine, poly-2- (dimethylamino) ethyl methacrylate, poly-2- (diethylamino) ethyl acrylate, cationized starch of primary amine type or tertiary amine type, and cationized cellulose of primary amine type or tertiary amine type, preferably branched polyethyleneimine and/or branched polypropyleneimine, and more preferably branched polyethyleneimine.

Preferably, the polyamine-based cationic polymer has a weight average molecular weight of 70,000 to 700,000, preferably 80,000 to 450,000, more preferably 90,000 to 150,000.

Under alkaline conditions, folic acid is anionic, can be assembled with a cationic polymer in an aqueous solution in supramolecules, and contains a pteridine ring, an aminobenzoic acid unit and an amino acid unit, so that the supramolecule has binding power, and an adhesive material with excellent performance can be formed.

The multi-amino cationic polymer contains a large amount of primary amino, secondary amino, tertiary amino and quaternary amino, is cationic in aqueous solution, can be subjected to super-molecular assembly with folic acid to obtain an aqueous super-molecular self-assembly body, and has good bonding performance on a wood material, so that the super-molecular wood adhesive is obtained. In particular, the branched polyethyleneimine has the characteristics of good dispersion, no peculiar smell, easy recycling and the like, and has the characteristics of low cost and easy synthesis. And the branched polyethyleneimine can be well combined with the wood material, so that the bonding strength of the wood material is effectively improved.

The branched polyethyleneimine has a weight average molecular weight of 75,000 to 400,000, preferably 85,000 to 250,000, more preferably 95,000 to 120,000.

The invention also provides a preparation method of the supramolecular wood adhesive, the preparation raw materials of the method comprise folic acid and the polyamino cationic polymer, and the raw materials are dispersed in the aqueous solution for preparation. The weight average molecular weight of the polyamino cationic polymer is from 70,000 to 700,000, preferably from 80,000 to 450,000, more preferably from 90,000 to 150,000.

The invention also provides the application of the supramolecular wood adhesive, which is used for adhering wood materials, wherein the shear adhesion strength is higher than 1.5MPa after 4 hours of adhesion, and the shear adhesion strength is higher than 3.6MPa after 7 hours of adhesion.

The supramolecular wood adhesive is prepared from raw materials including folic acid and a poly-amino cationic polymer, preferably, the adhesive is prepared in an aqueous solvent.

The polyamine-based cationic polymer comprises one or more of primary amine groups, secondary amine groups, tertiary amine groups and quaternary amine groups, preferably comprises two or three of primary amine groups, secondary amine groups, tertiary amine groups and quaternary amine groups, and more preferably comprises the primary amine groups, the secondary amine groups and the tertiary amine groups at the same time. Preferably, the polyamine-based cationic polymer has a weight average molecular weight of 70,000 to 700,000, preferably 80,000 to 450,000, more preferably 90,000 to 150,000.

Preferably, the polyamine-based cationic polymer is selected from one or more of branched polyethyleneimine (b-PEI), branched polypropyleneimine, poly-2- (dimethylamino) ethyl methacrylate, poly-2- (diethylamino) ethyl acrylate, cationized starch of primary amine type or tertiary amine type, and cationized cellulose of primary amine type or tertiary amine type, preferably branched polyethyleneimine and/or branched polypropyleneimine, and more preferably branched polyethyleneimine.

The branched polyethyleneimine has a weight average molecular weight of 75,000 to 400,000, preferably 85,000 to 250,000, more preferably 95,000 to 120,000.

The supramolecular wood adhesive is prepared by dispersing a raw material comprising folic acid and a poly-amino cationic polymer in an aqueous solution, and specifically comprises the following steps:

step 1, dissolving folic acid in water to obtain folic acid solution.

Adding folic acid into water, stirring and mixing to dissolve folic acid in water to obtain folic acid solution. Preferably, a basic substance is added to the folic acid solution to adjust the pH of the solution.

The mass concentration of the folic acid solution is 0.5-2.0%, preferably 0.7-1.5%, and more preferably 0.9-1.2%. The dissolution temperature is 15-35 ℃, preferably 20-30 ℃.

The alkaline substance is selected from water-soluble alkaline substances, preferably water-soluble inorganic alkali, more preferably water-soluble inorganic strong alkali, such as sodium hydroxide and potassium hydroxide.

The water is industrial water, distilled water, deionized water or ultrapure water, preferably distilled water, deionized water or ultrapure water, and more preferably ultrapure water.

The pH of the folic acid solution is greater than 8, preferably from 8.5 to 12, more preferably from 9 to 11.

And 2, dissolving the polyamine-based cationic polymer in water to obtain a solution II.

And adding the polyamine-based cationic polymer into water, stirring and mixing to dissolve the polyamine-based cationic polymer in the water to obtain a solution II. The dissolution temperature is 15-35 ℃, preferably 20-30 ℃. The water is industrial water, distilled water, deionized water or ultrapure water, preferably distilled water, deionized water or ultrapure water, and more preferably ultrapure water.

In the solution II, the concentration of the polyamino cationic polymer is 6-18mg/mL, preferably 9-15mg/mL, and more preferably 11-13mg/mL.

And 3, mixing and stirring the folic acid solution and the solution II, and separating to obtain the supermolecule wood adhesive.

And uniformly mixing and stirring the folic acid solution and the solution II to obtain the mixed solution with the temperature of 15-35 ℃ and preferably 20-30 ℃.

Separating supernatant, washing the obtained aggregate with water for 3-7 times to obtain supramolecular wood adhesive. The water is industrial water, distilled water, deionized water or ultrapure water, preferably distilled water, deionized water or ultrapure water, and more preferably ultrapure water.

The volume ratio of the folic acid solution to the solution II is (0.7-1.8): 1, preferably (0.85-1.5): 1, and more preferably (1.0-1.2): 1.

According to the invention, folic acid and the multi-amino cationic polymer are used as raw materials, the supramolecular wood adhesive is prepared in a water system, a reaction auxiliary agent and an organic reagent are not needed, the reaction is carried out at room temperature, and the preparation method is simple, green and environment-friendly. The prepared supermolecule wood adhesive has excellent adhesive capacity and mechanical property, particularly, the adhesive strength of a wood material is greatly improved, the adhesion is durable, the requirements of industrial production and use can be met, and the popularization, the production and the application are facilitated.

Examples

Example 1

Dissolving 1.1g of folic acid in 100mL of ultrapure water at room temperature to prepare a folic acid solution, dropwise adding a 2mol/L NaOH solution, and respectively adjusting the pH of the folic acid solution to 9, 10 and 11. 4g of a branched polyethyleneimine solution with a mass fraction of 30wt% was dissolved in 100mL of ultrapure water to prepare a branched polyethyleneimine solution with a concentration of about 12 mg/mL.

Respectively mixing folic acid solutions with different pH values with 12mg/mL branched polyethyleneimine solution in equal volume, shaking uniformly to obtain a mixed solution containing orange-yellow condensate, and pouring out the supernatant to obtain the condensate; washing the condensate with ultrapure water for 3 times to respectively obtain the folic acid-bPEI supermolecule wood adhesive: FA-bPEI-9 (pH 9 of the folic acid solution), FA-bPEI-10 (pH 10 of the folic acid solution), FA-bPEI-11 (pH 11 of the folic acid solution). Wherein the weight average molecular weight of the branched polyethyleneimine is 100,000-110,000, and the branched polyethyleneimine is purchased from Waverolidae reagent.

And (3) respectively carrying out infrared spectrogram test on folic acid (FA-9), branched polyethyleneimine (b-PEI) and the prepared folic acid-bPEI supramolecular wood adhesive FA-bPEI-9, wherein the test spectrogram is shown in figure 1. It can be observed from FIG. 1 that the unpaired oscillation peak of carboxylate radical is from 1403cm ^-1 Moved to 1386cm ^-1 And the peak of N-H bending vibration of b-PEI is from 1666cm ^-1 Moved to 1682cm ^-1 This is probably due to hydrogen bonding between folic acid and b-PEI, and this interaction leads to a certain cohesion of the material, and shows that folic acid-bPEI supramolecular wood adhesive is prepared by the method.

Examples of the experiments

Experimental example 1

The folic acid-bPEI supramolecular wood adhesive prepared in the example 1 is tested for water content, and the experimental method is as follows: firstly, the mass m of the folic acid-bPEI supermolecule wood adhesive is measured ₁ (ii) a Then, it was dried in a vacuum drying oven at a vacuum degree of-0.1MPa at 60 ℃ until the mass no longer changed, at which time the mass was m ₂ (ii) a Water cut = (m) ₁ -m ₂ )/m ₁ ×100％。

The obtained FA-bPEI-9 has the water content of 52.5%, the FA-bPEI-10 has the water content of 54.8% and the FA-bPEI-11 has the water content of 59.6%.

Experimental example 2

FA-bPEI-9 prepared in example 1 was lyophilized and then subjected to Scanning Electron Microscopy (SEM) test, the SEM test chart of which is shown in FIG. 2.

As can be seen from FIG. 2, the freeze-dried FA-bPEI-9 is a three-dimensional network structure due to the loss of water under freeze-drying, and in addition, the network structure also indicates that the material has certain mechanical strength, so that the material has the characteristics of good cohesion and adhesion.

Experimental example 3

The folic acid-bPEI supramolecular wood adhesive FA-bPEI-9 prepared in example 1 was tested using high resolution mass spectrometry (FT-MS) and X-ray diffraction (XRD).

As can be seen from the high resolution mass spectrum of FIG. 3, the peak with a mass to charge ratio of 1765.56 corresponds to a tetrad (C) ₇₆ H ₇₇ N ₂₈ O ₂₄ ) ⁺ The ion peak of (a), indicates that the pteridine part of the folic acid molecule forms a tetrad structure through hydrogen bonds.

In addition, from the XRD pattern of fig. 4, a diffraction broad peak of 2 θ =23.3 ° was obtained, representing the distance of pi-pi stacking

The tetrad structure is proved to form a high-grade assembly structure through pi-pi action.

Experimental example 4

The rheological properties of the folic acid-bPEI supramolecular wood adhesives FA-bPEI-9, FA-bPEI-10 and FA-bPEI-11 prepared in example 1 were measured using a ThermoHaake RS300 type rheometer. The test method comprises the following steps: placing folic acid-bPEI supermolecule wood adhesive between a chassis with the diameter of 35mm and a flat turntable, wherein the height of a gap is 0.1mm; the temperature was measured with a water bath of the type Pheonix by temperature control program setting. In the oscillation test, the frequency was set to 0.1-100Hz. The test results are shown in fig. 5.

As can be seen from FIG. 5, the loss modulus G 'of the prepared folic acid-bPEI supramolecular wood adhesive is larger than the storage modulus G', and the property of fluid is further confirmed.

Experimental example 5

The folic acid-bPEI supramolecular wood adhesive FA-bPEI-9 prepared in the embodiment 1 is used for bonding a tung wood test piece, and the shear adhesion strength after bonding is tested.

0.02g of folic acid-bPEI supramolecular wood adhesive FA-bPEI-9 is respectively coated on two same test pieces with the coating area of 2cm multiplied by 2cm, the other two test pieces made of the same material are respectively bonded with the two test pieces, and the two test pieces are cured at room temperature. The bonded coupons were then subjected to shear testing using a universal stretcher INSTRON Series 5943 (USA). The maximum tensile force (unit: N) at the time of specimen separation or adhesive layer rupture was divided by the adhesion area (cm) ² ) The shear adhesion strength (unit: kPa).

After curing for 4 hours and 7 hours, respectively, the two sets of test pieces tested 1.51MPa and 3.68MPa shear adhesion strength to wood, respectively, higher than that of commercial glue. Wherein, the shear adhesion strength of the universal adhesive (purchased from Beijing Dehang Wuzhou science and technology Co., ltd., brand: JSENB) and the shear adhesion strength of the 3M double-sided adhesive bonded tung wood test piece are respectively 2.55MPa and 0.25MPa under the same condition by the same method.

The fracture pattern of the chips after the shear test was analyzed. The adhered tung wood test piece cured for 4 hours at room temperature has a fracture mode of fracture at the adhered layer, which shows that the interaction force is not stable yet, and the adhesive strength is not maximum yet, as shown in fig. 6; the fracture mode of the adhered tung wood test piece after being cured for 7 hours at room temperature is matrix fracture, as shown in fig. 6, which shows that the adhesion strength is stronger than that of the tung wood test piece per se, and shows that the adhesive capacity of the folic acid-bPEI supramolecular adhesive is further improved after being cured for 7 hours.

Experimental example 6

The folic acid-bPEI supramolecular wood adhesive FA-bPEI-9 prepared in example 1 was used to adhere tung wood chips with an adhesion area of 2.7cm x 3.0cm, and cured at room temperature for 7 hours. Through a physical bearing test, two wood chips adhered together can bear a weight of 50Kg, and after adhering for 180 days, the wood chips can still bear a weight of 50Kg, which shows that the adhesive capacity of the supramolecular wood adhesive provided by the invention is durable.

The folic acid-bPEI supramolecular wood adhesive FA-bPEI-9 prepared in the example 1 is used for adhering wood chips, two wood chips are respectively adhered to two ends of a third wood chip to form a wood bridge, and the adhering areas are 2.0cm multiplied by 5.0cm. And applying a weight of 55.45kg in the vertical direction perpendicular to the plane of the wooden bridge to ensure that the adhesion surfaces at the two ends of the third wood chip are stressed and the adhesion condition of the wood chips is good. The result shows that the adhesive material has strong macroscopic adhesive capacity and can meet the practical application.

Experimental example 7

The folic acid-bPEI supramolecular wood adhesive FA-bPEI-9 prepared in the example 1 is used for adhering two tung wood chips and curing the two tung wood chips for 7 hours at room temperature. At the adhesion, two adhered wood chips are cut perpendicular to the plane of the wood chips. Scanning Electron Microscopy (SEM) was performed on the cross-sectional fault, and the SEM image obtained by the test is shown in FIG. 7 (a).

As can be seen from the SEM test result of FIG. 7 (a), the wood is porous structure, and the folic acid-bPEI supramolecular wood adhesive FA-bPEI-9 in the water system can easily penetrate into the wood chip and form mutual mechanical interlocking after curing, and the schematic diagram is shown in FIG. 7 (b).

The folic acid-bPEI supramolecular wood adhesive FA-bPEI-9 prepared in the embodiment 1 is dried in vacuum and then is crushed and ground to obtain FA-bPEI-9 powder. Mixing FA-bPEI-9 powder with dried lignin or cellulose powder (the lignin powder and the cellulose powder are commercially available), grinding uniformly to obtain a uniformly mixed FA-bPEI-9 and lignin mixture, FA-bPEI-9 and cellulose mixture, and performing infrared test on a sample to be tested at room temperature by using a potassium bromide tabletting method.

The IR test spectra of the FA-bPEI-9 powder, lignin, FA-bPEI-9 and lignin mixture are shown in FIG. 8. The IR test spectrum of the FA-bPEI-9 powder, the cellulose, the FA-bPEI-9 and the fiber mixture is shown in FIG. 9. It can also be seen from the above infrared test spectra that after FA-bPEI-9 was mixed with lignin and cellulose, respectively, 1682cm ^-1 The peak red-shifted to 1675cm ^-1 The acting force of the supramolecular wood adhesive FA-bPEI-9 and lignin and cellulose in wood can be laterally reflected.

The invention has been described in detail with reference to specific embodiments and/or illustrative examples and the accompanying drawings, which, however, should not be construed as limiting the invention. Those skilled in the art will appreciate that various equivalent substitutions, modifications or improvements may be made to the embodiments and implementations of the invention without departing from the spirit and scope of the invention, and are within the scope of the invention. The scope of the invention is defined by the appended claims.

Claims (10)

1. Supramolecular wood adhesives are prepared from raw materials comprising folic acid and polyamino cationic polymers, preferably the adhesives are prepared in aqueous solvents.

2. An adhesive according to claim 1 wherein the polyamine-based cationic polymer comprises one or more of primary, secondary, tertiary and quaternary amine groups, preferably two or three of primary, secondary, tertiary and quaternary amine groups, more preferably the polyamine-based cationic polymer comprises both primary, secondary and tertiary amine groups.

3. The preparation method of the supramolecular wood adhesive is characterized in that raw materials for preparing the supramolecular wood adhesive comprise folic acid and a polyamino cationic polymer, and the raw materials are dispersed in an aqueous solution for preparation.

4. The method of claim 3, wherein the polyamine-based cationic polymer has a weight average molecular weight of 70,000 to 700,000, preferably 80,000 to 450,000.

5. Use of the adhesive according to claim 1 or 2 or the supramolecular wood adhesive prepared by the method according to claim 3 or 4 for adhering wood materials with a shear adhesion strength higher than 1.5MPa after 4 hours of bonding and a shear adhesion strength higher than 3.6MPa after 7 hours of bonding.

6. Use according to claim 5,

the supramolecular wood adhesive is prepared from raw materials including folic acid and a polyamino cationic polymer, wherein the polyamino cationic polymer comprises one or more of primary amine group, secondary amine group, tertiary amine group and quaternary amine group;

the weight average molecular weight of the polyamino cationic polymer is from 70,000 to 700,000, preferably from 80,000 to 450,000;

preferably, the polyamine-based cationic polymer is selected from one or more of branched polyethyleneimine (b-PEI), branched polypropyleneimine, poly-2- (dimethylamino) ethyl methacrylate, poly-2- (diethylamino) ethyl acrylate, primary amine type or tertiary amine type cationized starch and primary amine type or tertiary amine type cationized cellulose.

7. Use according to claim 5, wherein the supramolecular wood adhesive is prepared from a starting material comprising folic acid and a polyamino cationic polymer, dispersed in an aqueous solution, preferably comprising in particular the following steps:

step 1, dissolving folic acid in water to obtain folic acid solution;

step 2, dissolving the polyamine-based cationic polymer in water to obtain a solution II;

and 3, mixing and stirring the folic acid solution and the solution II, and separating to obtain the supermolecule wood adhesive.

8. Use according to one of claims 5 to 7, characterized in that in step 1, the folic acid solution has a mass concentration of 0.5% to 2.0% and a pH value of more than 8, preferably of 8.5 to 12, more preferably of 9 to 11.

9. Use according to one of claims 5 to 7, characterized in that, in step 2,

dissolving the polyamine-based cationic polymer in water at the temperature of 15-35 ℃;

in the solution II, the concentration of the polyamino cationic polymer is 6-18mg/mL, preferably 9-15mg/mL, and more preferably 11-13mg/mL.

10. Use according to one of claims 5 to 7, characterized in that in step 3, the volume ratio of the folic acid solution to solution II is (0.7-1.8): 1.

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