CN103740325B - Adhesion agent for artificial board, its preparation method and utilize its glued board - Google Patents

Abstract

The invention relates to an adhesive for artificial boards, a preparation method thereof and a plywood using the adhesive. The raw materials of the adhesive for wood-based panels include: dispersion medium, protein substances, basic compounds and crosslinking enhancer; the crosslinking enhancer is furfuryl alcohol furfural type furan resin. The adhesive for wood-based panels provided by the invention does not contain formaldehyde, and the main raw material is derived from renewable substances. It is an environmentally friendly adhesive for wood-based panels; it completely solves the problem of formaldehyde pollution when using adhesives, and at the same time ensures the water resistance of the adhesive. Practical properties such as bonding strength; at the same time, compared with the existing technology, each component plays a good synergistic effect, which enhances the effect; the preparation method is simple, and does not require a long curing time, easy to operate, and high production efficiency; overall In terms of comprehensive utilization of resources, saving production costs, in line with the principles of environmental protection and sustainable development, it has a good application prospect.

Description

Adhesive for wood-based panels, preparation method thereof, and plywood using the same

technical field

The invention relates to the field of chemical materials, in particular to an adhesive for wood-based panels, a preparation method thereof and a plywood using the adhesive.

Background technique

With the rapid development of construction, decoration, packaging and other industries, the output of wood-based panels in my country has increased rapidly. In 2012, the total output of wood-based panels in my country was 286 million square meters, accounting for about 50% of the world's total output. Among them, particleboard was 12.89 million square meters, a year-on-year increase of 7.2%; fiberboard was 55.54 million square meters, a year-on-year increase of 13.1%; plywood was 142 million square meters, a year-on-year increase of 18.3%. The total output of wood-based panels, plywood, furniture and wood flooring has ranked first in the world for many years.

The adhesives commonly used in the production of wood-based panels are formaldehyde-based synthetic resins, mainly urea-formaldehyde resins and their modified products. Although after years of hard work, the production level of wood-based panel adhesives in my country has been greatly improved, and the environmental protection characteristics of wood-based panels and their products have been greatly improved, but many enterprises produce wood-based panels and their products (furniture, wooden floors and indoor wood). There is still a relatively serious formaldehyde release problem, which is the main source of formaldehyde pollution in indoor air pollution.

At present, there are mainly four methods to reduce the release of formaldehyde from wood-based panels: 1) Using low molar ratio modified urea-formaldehyde resin adhesive; 2) Adding formaldehyde scavenger to the modified urea-formaldehyde resin adhesive; 3) Post-treatment of wood-based panels ; 4) Use other environmentally friendly adhesives. However, there are many defects in these technologies. For example: 1) Although the use of a low molar ratio modified urea-formaldehyde resin adhesive can effectively reduce the formaldehyde emission of wood-based panel products, the bonding strength of the product is often reduced, which cannot meet the requirements of use; and the curing time is prolonged and the production efficiency is reduced; 2) Adding formaldehyde scavenger to urea-formaldehyde resin adhesives for wood-based panels can effectively reduce the release of free formaldehyde from wood-based panels, but it often also reduces the bonding strength of wood-based panels; at the same time, the price of general formaldehyde scavenger is often much higher than that of urea-formaldehyde resin adhesives. , its addition increases product cost and reduces product competitiveness; 3) Carry out post-processing to wood-based panels, such as the invention patent application with publication number CN1526528 (public date: September 8, 2004) discloses a method using The manufacturing process of E1/EO grade environment-friendly wood-based panels prepared by ammonia vacuum method; the utility model patent with publication number CN2394770 (public date: September 6, 2000) discloses a treatment device for reducing formaldehyde emission from wood-based panels ; These post-processing methods not only make the manufacturing process of wood-based panels complicated, but also require huge investment in post-processing equipment and significantly increase production costs; The production process is more difficult, which is difficult for both enterprises and users to accept; moreover, there may still be problems in the disposal of its glued products (for example, poisonous gas hydrogen cyanide may be produced during incineration); The bonding strength of the board is low, and the wood-based board is easy to open the glue. In summary, although the above technical means can effectively reduce the release of free formaldehyde from wood-based panels, they cannot completely solve the problem of formaldehyde release, or cannot be popularized due to high production costs and other reasons.

In addition, the currently widely used wood-based panel adhesives also have the problem of dependence on fossil resources of raw materials, which do not meet the requirements of sustainable development.

Contents of the invention

In order to solve the above technical problems, one of the objectives of the present invention is to provide an adhesive for wood-based panels; the adhesive does not contain formaldehyde, and its main raw materials are derived from renewable substances.

Another object of the present invention is to provide a method for preparing the adhesive for wood-based panels.

Another object of the present invention is to provide a plywood using the adhesive for wood-based panels.

In order to achieve the above object, one aspect of the present invention provides an adhesive for wood-based panels, the raw materials of which include: dispersion medium, protein substances, basic compounds and cross-linking enhancers.

Wherein, the crosslinking enhancer is furfuryl alcohol furfural type furan resin. The furfuryl alcohol furfural type furan resin can be synthesized under certain conditions, either by self-made or purchased. Its role in the adhesive formulation for wood-based panels of the present invention is to react with active groups on proteins to increase the cross-linking density of the adhesive and improve the water-resistant bonding performance. The present invention uses the properties of active groups such as hydroxyl and aldehyde groups in the resin structure to improve the water-resistant bonding performance of protein adhesives through chemical crosslinking reactions with protein active groups, and has no formaldehyde release, environmental protection, no corrosion, acid and alkali resistance performance applications.

The adhesive for wood-based panels provided by the invention comprises the following raw materials in parts by weight: 60-70 parts of dispersion medium, 20-35 parts of protein substances, 0.5-3 parts of basic compound and 1-5 parts of cross-linking enhancer.

The adhesive for wood-based panels provided by the present invention preferably comprises the following raw materials in parts by weight: 62-70 parts of dispersion medium, 25-30 parts of protein substances, 1-2.5 parts of basic compound and 1-4 parts of cross-linking enhancer . The dispersion medium is more preferably 64-70 parts, the protein substance is more preferably 28-30 parts, and the basic compound is more preferably 1-2 parts.

Wherein, the dispersion medium is water, preferably demineralized water. It provides a dispersion environment for the adhesive in the adhesive formula for the wood-based panel of the invention; the cost is low, the safety is high and the effect is good.

Wherein, the protein substance is defatted soybean protein, soybean meal protein, peanut meal protein or jatropha seed protein, etc.; defatted soybean protein is preferred, and the form is preferably powdery, that is, defatted soybean protein powder.

Wherein, the basic compound is sodium carbonate, sodium hydroxide or potassium hydroxide; preferably sodium carbonate.

The effect of proteinaceous matter, especially defatted soybean protein powder in the adhesive formula for wood-based panel of the present invention is the main bonding component; the effect of alkaline compound, especially sodium carbonate in the adhesive formula for wood-based panel of the present invention is: to make protein Denaturation exposes internal reactive groups.

The preparation method of any of the above-mentioned adhesives for wood-based panels provided in another aspect of the present invention comprises the following steps:

1) Disperse protein substances and basic compounds in the dispersion medium;

2) Add cross-linking enhancer and stir evenly.

Wherein, in step 1), the basic compound and the protein substance are added to the dispersion medium and stirred evenly, so that the obtained mixture (basic compound, protein substance and dispersion medium) is at 40-80°C, preferably at 40-70°C Keep warm for 3-6 hours.

Wherein, in step 2), the cross-linking enhancer is added when the mixture obtained in the previous step is cooled to 25-35° C., and stirred evenly.

Wherein, the weight ratio of raw materials is: 60-70 parts of dispersion medium, 20-35 parts of protein substances, 0.5-3 parts of basic compound, and 1-5 parts of cross-linking enhancer.

Further, the weight ratio of raw materials is preferably: 62-70 parts of dispersion medium, 25-30 parts of protein substances, 1-2.5 parts of basic compound, and 1-4 parts of cross-linking enhancer. The dispersion medium is more preferably 64-70 parts, the protein substance is more preferably 28-30 parts, and the basic compound is more preferably 1-2 parts.

Wherein, the crosslinking enhancer is furfuryl alcohol furfural type furan resin, and its synthesis process is:

Mix 100 parts by weight of furfuryl alcohol and 100 parts by weight of furfural and stir, add 1 part by weight of oxalic acid, and stir until the oxalic acid dissolves; heat until the material refluxes, start viscosity measurement, react until the viscosity is 14 to 16 seconds, cool down to below 70°C, add Appropriate amount of strong base compound, adjust the pH value to neutral (about 7.0), cool down to 30°C and discharge, discard the water layer, and the product is obtained.

In the synthetic technique of above-mentioned furfuryl alcohol furfural type furan resin:

The strong base compound is sodium hydroxide or potassium hydroxide.

The reaction device is a reaction kettle.

The strong base compound is an aqueous solution with a mass concentration of 30%.

Said viscosity is measured with Tu-4 cup at 70°C.

Wherein, the dispersion medium is water, preferably demineralized water. It provides a dispersion environment for the adhesive in the adhesive formula for the wood-based panel of the invention; the cost is low, the safety is high and the effect is good.

Wherein, the protein substance is defatted soybean protein, soybean meal protein, peanut meal protein or jatropha seed protein, etc.; defatted soybean protein is preferred, and the form is preferably powdery, that is, defatted soybean protein powder.

Wherein, the basic compound is sodium carbonate, sodium hydroxide or potassium hydroxide; preferably sodium carbonate.

The adhesive of the present invention is mainly used for plywood.

The present invention also provides a plywood using any one of the above-mentioned adhesives for wood-based panels, wherein the glue amount of the adhesive for wood-based panels is 280-320 g/m ² .

The present invention has the following advantages:

1) Use protein substances, especially defatted soybean protein powder, as raw materials for wood-based panel adhesives, which do not contain free formaldehyde, and there is no formaldehyde release problem when used to glue wood-based panels, completely solving the problem of indoor air caused by wood-based panels. Formaldehyde pollution problem.

2) Proteins, as a renewable resource and the main raw material of adhesives, help to solve the problem of depletion of synthetic fossil raw materials used in conventional wood-based panel adhesives, which is in line with the principles of environmental protection and sustainable development.

3) The obtained adhesive is processed from protein substances, which effectively utilizes soybean processing residues, comprehensively utilizes resources, saves production costs, and increases the added value of products.

4) Using furfuryl alcohol furfural type furan resin as cross-linking enhancer solves the problem of poor water resistance of ordinary soybean protein adhesives, can meet the water resistance requirements of adhesives for wood-based panels, and ensures the practical performance of the adhesive such as bonding strength; and the adhesive of the present invention The prepared plywood meets the requirements of type II plywood in the national standard, has high bonding strength and will not be glued.

5) Furfuryl alcohol furfural type furan resin cross-linking enhancer is used. The main raw materials of furfural and furfuryl alcohol come from corncobs of agricultural and sideline products, which helps to solve the problem of depletion of synthetic fossil raw materials used in ordinary adhesives, and conforms to the principles of environmental protection and sustainable development.

In a word, the adhesive for wood-based panels provided by the present invention does not contain formaldehyde, and the main raw material is derived from renewable substances. It is an environmentally friendly adhesive for wood-based panels; it completely solves the problem of formaldehyde pollution when using adhesives, and at the same time ensures the water resistance of the adhesives Practical properties such as safety and bonding strength; at the same time, compared with the existing technology, each component plays a good synergistic effect, making the effect stronger; the preparation method is simple, and does not require a long curing time, convenient operation, and high production efficiency ; Overall comprehensive utilization of resources, saving production costs, in line with the principles of environmental protection and sustainable development, has a good application prospect.

detailed description

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

Operations not mentioned in the present invention are routine operations in this field,

Used in the present invention: defatted soybean protein powder was purchased from Shandong Xiangchi Grain and Oil Co., Ltd., and furfural and furfuryl alcohol were purchased from Beijing Chemical Reagent Company.

Sodium carbonate used in the present invention is powdery.

The synthesis process of the furfuryl alcohol furfural type furan resin of the present invention is as follows: 100 parts by weight of furfuryl alcohol and 100 parts by weight of furfural are added to the reaction device, stirring is started, 1 part by weight of oxalic acid is added, and the oxalic acid is stirred until the oxalic acid is dissolved; the material is heated to reflux, and the viscosity is measured. React until the viscosity is 15 seconds, lower the temperature to below 70°C, add an appropriate amount of sodium hydroxide, adjust the pH value to neutral, lower the temperature to 30°C and discharge, discard the water layer to obtain the product. The obtained furfuryl alcohol furfural type furan resin has a weight average molecular weight of 4000-8000, a viscosity of 500-600 mPa·s, and an appearance of a red transparent liquid.

Other materials used in the present invention are conventional materials that can be purchased from the market.

In the present invention, the unit "part" or "part by weight" refers to kilogram, gram, etc., which can be determined according to specific circumstances.

Example 1

1) Prepare materials according to the following weight:

Softened water 70kg

Sodium carbonate 1kg

Defatted Soy Protein Powder 28kg

Furfuryl alcohol furfural type furan resin 1kg;

2) Add sodium carbonate and defatted soybean protein powder into demineralized water in a reaction kettle equipped with a stirrer, thermometer and condensing device, and stir evenly;

3) Heat the obtained mixture of sodium carbonate, defatted soybean protein powder and demineralized water to 45-47°C and keep it warm for 3 hours;

4) Cool down the mixture obtained in the previous step to 30°C to obtain a uniform soy protein mucus;

5) Add furfuryl alcohol furfural furan resin to the soy protein mucus obtained in the previous step, and stir evenly to make a soy protein adhesive for wood-based panels.

The performance and quality indicators of the obtained adhesive are shown in Table 1.

Example 2

1) Prepare materials according to the following weight:

Demineralized water 65kg

Sodium carbonate 2kg

Defatted Soy Protein Powder 30kg

Furfuryl alcohol furfural type furan resin 3kg;

2) Add sodium carbonate and defatted soybean protein powder into demineralized water in a reaction kettle equipped with a stirrer, thermometer and condensing device, and stir evenly;

3) Heat the obtained mixture of sodium carbonate, defatted soybean protein powder and demineralized water to 40-42°C and keep it warm for 6 hours;

4) Cool down the mixture obtained in the previous step to 30°C to obtain a uniform soy protein mucus;

5) Add furfuryl alcohol furfural furan resin to the soy protein mucus obtained in the previous step, and stir evenly to make a soy protein adhesive for wood-based panels.

The performance and quality indicators of the obtained adhesive are shown in Table 1.

Example 3

1) Prepare materials according to the following weight:

Demineralized water 64kg

Sodium carbonate 2kg

Defatted Soy Protein Powder 30kg

Furfuryl alcohol furfural type furan resin 4kg;

2) Add sodium carbonate and defatted soybean protein powder into demineralized water in a reaction kettle equipped with a stirrer, thermometer and condensing device, and stir evenly;

3) Heat the obtained mixture of sodium carbonate, defatted soybean protein powder and demineralized water to 68-70°C and keep it warm for 5 hours;

4) Cool down the mixture obtained in the previous step to 30°C to obtain a uniform soy protein mucus;

5) Add furfuryl alcohol furfural furan resin to the soy protein mucus obtained in the previous step, and stir evenly to make a soy protein adhesive for wood-based panels.

The performance and quality indicators of the obtained adhesive are shown in Table 1.

In Table 1, the unit "%" of solid content and free formaldehyde content is mass percentage.

Table 1: Performance and quality indicators of adhesives

It can be seen from Table 1 that the solid content and viscosity of the adhesives obtained in Examples 1-3 are relatively high, and the pH value is alkaline; they do not contain formaldehyde and can be stored for at least 20 days.

Experimental example

The corresponding products of Examples 1-3 of the present invention and Comparative Examples 1-3 (soybean protein mucilage in Examples 1-3 are used as adhesive, that is, no cross-linking enhancer) are used to manufacture three-layer plywood of 450×450 mm.

Plywood is prepared as follows:

Glue sizing: Glue is applied on both sides of the core board, and the amount of glue applied is 280~320g/m ² .

Aging method and time: closed aging, 10-30 minutes.

Pre-compression pressure and time: pre-compression for 30 minutes, pressure 0.8MPa.

Hot pressing pressure: 1.1MPa, hot pressing temperature is 120-130°C, hot pressing time is 70s/mm.

According to the test method of GB/T17657-1999 "Physical and Chemical Properties of Wood-based Panels and Decorated Wood-based Panels", the performance test of the produced plywood products is carried out. The test results are shown in Table 2.

Table 2: Formaldehyde emission and bonding strength of glued plywood

The amount of formaldehyde released by the state, the standard of type II plywood: E0 standard ≤ 0.5mg/L, which is the highest standard for environmental protection; E1 standard is 0.5-1.5mg/L; E2 standard is 1.5-5.0mg/L.

Experimental results show that the plywood produced by the formaldehyde-free soybean protein adhesive of the present invention has very low formaldehyde emission (and is the formaldehyde emission of the wood body), which is far below the upper limit of the highest environmental protection standard for formaldehyde emission stipulated by the state; The bonding strength is above 1.20MPa, reaching the national standard for Class II plywood (poplar wood ≥ 0.70MPa); without adding cross-linking enhancer, it cannot be glued well, which will cause the plywood to be glued.

cost analysis:

The formaldehyde-free soy protein adhesive of the present invention is easy to use, does not need to modify the existing wood-based panel production equipment and process, and therefore does not need to increase equipment investment.

At present, the price of environment-friendly melamine-modified urea-formaldehyde resin adhesive with 50% solid content is 1,800-2,500 yuan/ton, and the price of phenolic resin adhesive is 5,000-6,000 yuan/ton. The cost is about 2,000 yuan/ton, which is far lower than that of phenolic resin adhesives and close to that of modified urea-formaldehyde resin adhesives.

The adhesive obtained by the invention can replace the conventional formaldehyde-containing adhesive for wood-based panels, and the total amount of glue used in the preparation of plywood remains unchanged, so the use cost is equivalent to that of urea-formaldehyde resin adhesives and far lower than the use cost of phenolic resin adhesives. Therefore, the soy protein adhesive of the present invention has good application prospects.

Although the present invention has been described in detail with general descriptions and specific embodiments above, it is obvious to those skilled in the art that some modifications or improvements can be made on the basis of the present invention. Therefore, the modifications or improvements made on the basis of not departing from the spirit of the present invention all belong to the protection scope of the present invention.

Claims (14)

1. an adhesion agent for artificial board, is characterized in that, this tackiness agent comprises the raw material of following weight part: 60 ~ 70 parts, dispersion medium, protein matter 20 ~ 35 parts, basic cpd 0.5 ~ 3 part and crosslinking enhancer 1 ~ 5 part; Described crosslinking enhancer is furfuryl alcohol furfural type furane resin.

2. adhesion agent for artificial board according to claim 1, is characterized in that, described tackiness agent comprises the raw material of following weight part: 62 ~ 70 parts, dispersion medium, protein matter 25 ~ 30 parts, basic cpd 1 ~ 2.5 part and crosslinking enhancer 1 ~ 4 part.

3. adhesion agent for artificial board according to claim 1 and 2, is characterized in that, described dispersion medium is water.

4. adhesion agent for artificial board according to claim 3, is characterized in that, described dispersion medium is softening water.

5. the adhesion agent for artificial board according to claim 1,2,4 any one, is characterized in that, described protein matter is degreasing soybean protein, dregs of beans albumen, peanut meal albumen or jatropha curcas seed albumen.

6. adhesion agent for artificial board according to claim 5, is characterized in that, described protein matter is degreasing soybean protein.

7. the adhesion agent for artificial board according to claim 4 or 6, is characterized in that, described basic cpd is sodium carbonate, sodium hydroxide or potassium hydroxide.

8. adhesion agent for artificial board according to claim 7, is characterized in that, described basic cpd is sodium carbonate.

9. the preparation method of adhesion agent for artificial board described in claim 1 ~ 8 any one, is characterized in that, said method comprising the steps of:

1) protein matter and basic cpd is made to be dispersed in dispersion medium;

2) add crosslinking enhancer, stir.

10. preparation method according to claim 9, is characterized in that, step 1) in, stir after basic cpd and protein matter are added dispersion medium, make the mixture of acquisition be incubated 3 ~ 6 hours at 40 ~ 80 DEG C.

11. preparation methods according to claim 10, is characterized in that, make the mixture of acquisition be incubated 3 ~ 6 hours at 40 ~ 70 DEG C.

12. preparation methods according to claim 9, is characterized in that, step 2) in, making step 1) mixture that obtains adds crosslinking enhancer when being cooled to 25 ~ 35 DEG C, and stirs.

13. preparation methods according to claim 9 ~ 12 any one, it is characterized in that, described crosslinking enhancer is furfuryl alcohol furfural type furane resin, and its synthesis technique is: stir after being mixed with 100 weight part furfurals by 100 parts by weight furfuryl alcohol, add 1 weight part oxalic acid again, be stirred to dissolving oxalic acid; Be heated to feed back, start viscosimetric, reacting to viscosity is 14 ~ 16 seconds, is cooled to less than 70 DEG C, adds highly basic compounds, and adjust pH is neutral, is cooled to 30 DEG C of dischargings, discards water layer, to obtain final product; Described highly basic compounds is sodium hydroxide or potassium hydroxide.

14. glued boards utilizing the adhesion agent for artificial board described in claim 1 ~ 8 any one, it is characterized in that, wherein the Amount of spread of adhesion agent for artificial board is 280 ~ 320g/m ².