CN104762059B - A kind of modified soy-bean protein base adhesive and preparation method thereof - Google Patents

Abstract

The invention discloses a modified soybean protein-based adhesive and a preparation method thereof. Prepared from 1-8 parts of sodium formate, the preparation steps include dispersing defatted soybean protein powder and urea in a dispersion medium, adding a cross-linking enhancer and sodium benzoate, and stirring evenly to obtain it; the advantages of the present invention are: simple production process and convenient operation , the adhesive produced does not contain formaldehyde, and the main raw materials are derived from renewable substances.

Description

A kind of modified soybean protein-based adhesive and preparation method thereof

technical field

The invention relates to an adhesive, in particular to a modified soybean protein-based adhesive used for preparing plywood and a preparation method thereof, belonging to the field of adhesives.

Background technique

With the improvement of people's living standards and the continuous and stable development of construction, decoration, packaging and other industries, the output of wood-based panels in my country has grown rapidly. In 2013, the total output of wood-based panels in China was 272 million m ³ , accounting for about 50% of the world's total output. Among them, particleboard was 13.58 million m ³ , a year-on-year increase of 5.3%; fiberboard was 59.83 million m ³ , a year-on-year increase of 4.0%; plywood was 157 million m ³ , a year-on-year increase of 10.5%. The total output of wood-based panels, plywood, furniture, and wood flooring has ranked first in the world for many years in a row.

The adhesives commonly used in the production of wood-based panels are formaldehyde-based synthetic resins, mainly urea-formaldehyde resins and their modified products. 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 the formaldehyde release of their products cannot be completely eliminated, and many enterprises produce wood-based panels and their products. (Furniture, wood flooring, indoor wood decoration materials, etc.) still have a serious problem of formaldehyde release, 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. But all there are many defectives in these technical methods. For example: 1) Although the use of low molar ratio modified urea-formaldehyde resin adhesives can effectively reduce the formaldehyde emission of wood-based panel products, the bonding strength of the products is often reduced, which cannot meet the requirements of use; and it can lead to prolonged curing time and reduced production efficiency; 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 reduces the bonding strength of wood-based panels at the same time; at the same time, the price of general formaldehyde scavenger is often much higher than that of urea-formaldehyde resin adhesives. Adding improves product cost and reduces product competitiveness; 3) Carry out post-processing to wood-based panels, as the invention patent application with publication number CN1526528 discloses a method for preparing E1/EO grade environment-friendly wood-based panels using ammonia vacuum method. Manufacturing process; the utility model patent with publication number CN2394770 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. ; 4) The use of other environmentally friendly adhesives, such as isocyanate adhesives, has led to a substantial increase in the production cost of wood-based panels and increased difficulty in the production process, which is difficult for enterprises and users to accept; Open glue. To sum up, although the above measures 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 reasons such as high production costs.

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 problems, the present invention designs a modified soybean protein-based adhesive and its preparation method. The production process is simple, the operation is convenient, the adhesive produced does not contain formaldehyde, and the main raw material comes from renewable substances. Adhesive for boards.

Technical scheme of the present invention is:

A modified soybean protein-based adhesive prepared from the following raw materials in parts by weight:

60-70 parts of dispersion medium, 20-35 parts of defatted soybean protein powder, 0.5-2 parts of urea, 2-15 parts of cross-linking enhancer, 1-8 parts of sodium benzoate; wherein, the cross-linking enhancer is melamine-cyclo Oxychloropropane-sodium hydroxide reactant.

Preferably, 62-68 parts of dispersion medium, 25-30 parts of defatted soybean protein powder, 1-2 parts of urea, 5-12 parts of cross-linking enhancer, and 2-4 parts of sodium benzoate.

Further, demineralized water is selected as the dispersion medium.

A preparation method of the above-mentioned modified soybean protein-based adhesive, comprising the following steps:

1) Weigh each raw material according to the above weight ratio to disperse the defatted soybean protein powder and urea in the dispersion medium;

2) Add cross-linking enhancer and sodium benzoate, and stir well.

Wherein, the reaction enhancer is melamine-epichlorohydrin-sodium hydroxide reactant, and the preparation method is as follows: 1 mol melamine and 10 mol water are placed in a four-necked flask at a constant temperature to 60°C, and 1% boron trifluoride and Dissolve 0.05mol of sodium hydroxide, mix well, slowly drop into 4mol of epichlorohydrin monomer and react at 70-90°C for 5 hours, then cool down to 50°C, add 0.15mol of sodium hydroxide, stir for 20 minutes, neutralize The excess alkali is distilled under reduced pressure to free epichlorohydrin, refined and dried in ethanol to obtain the reaction enhancer of the present invention.

The advantages of the present invention are:

1) The present invention treats soy protein as an adhesive for wood-based panels, does not contain free formaldehyde, and the glued wood-based panels do not have the problem of formaldehyde release, which completely solves the problem of formaldehyde pollution in indoor air caused by wood-based panels;

2) As a renewable resource, soybean protein, as the main raw material of adhesives, helps 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 soy protein adhesive of the present invention is processed from defatted soy protein powder, effectively utilizes soybean processing residues, comprehensively utilizes resources, saves production costs, and increases product added value;

4) The present invention uses melamine-epichlorohydrin-sodium hydroxide reactant as a cross-linking enhancer, which 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 durability of soybean protein adhesives. Practical performance, and the plywood prepared by the adhesive of the present invention meets the requirements of class II plywood in the national standard.

The present invention will be further described below in conjunction with specific examples.

detailed description

Preferred embodiments of the present invention are described below, and it should be understood that the preferred embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

Unless otherwise stated, the percentages used in the present invention are all percentages by weight.

Example 1

A kind of modified soybean protein-based adhesive and preparation method thereof

1) Prepare materials according to the following weight ratio:

Demineralized water 68kg

Urea 1kg

Defatted Soy Protein Powder 26kg

Enhancer 6 kg

Sodium Benzoate 2kg

2) Add all the demineralized water, soybean protein powder and urea into the reaction kettle equipped with agitator, thermometer and condensing device, and stir evenly;

3) Heat in a water bath to 40-45°C and keep warm for 3 hours;

4) The temperature of the reactant is lowered to 30°C to obtain a uniform soy protein mucus;

5) Add the enhancer to the obtained soybean protein mucilage, mix well, and then add sodium benzoate to make the soybean protein adhesive.

Among them, the performance and quality indicators of the adhesive are shown in Table 1.

Example 2

A kind of modified soybean protein-based adhesive and preparation method thereof

1) Prepare materials according to the following weight ratio:

Demineralized water 64 kg

Urea 1.5 kg

Defatted Soy Protein Powder 29 kg

Enhancer 8kg

Sodium Benzoate 4kg

2) Add all the demineralized water, soybean protein powder and urea into the reaction kettle equipped with agitator, thermometer and condensing device, and stir evenly;

3) Heat in a water bath to 40-45°C and react for 6 hours;

4) The temperature of the reactant was lowered to 30°C to obtain a uniform soy protein mucus.

5) Add the enhancer to the obtained soybean protein mucilage, mix well, and then add sodium benzoate to make the soybean protein adhesive.

Among them, the quality index of soybean protein adhesive is shown in Table 1.

Example 3

A kind of modified soybean protein-based adhesive and preparation method thereof

1) Prepare materials according to the following weight ratio:

Demineralized water 62 kg

Urea 2 kg

Defatted Soy Protein Powder 29 kg

Enhancer 10kg

Sodium Benzoate 3kg

2) Add all the demineralized water and soybean protein powder into the reaction kettle equipped with agitator, thermometer and condensing device, and stir evenly;

3) Heat in a water bath to 65-70°C and react for 5 hours;

4) The temperature of the reactant is lowered to 30°C to obtain a uniform soy protein mucus;

5) Add the enhancer to the obtained soybean protein mucilage, mix well, and then add sodium benzoate to make the soybean protein adhesive.

Among them, the performance and quality indicators of the adhesive are shown in Table 1.

Example 4

A kind of modified soybean protein-based adhesive and preparation method thereof

1) Prepare materials according to the following weight ratio:

Demineralized water 62 kg

Urea 2 kg

Defatted Soy Protein Powder 28 kg

Enhancer 12kg

Sodium Benzoate 3kg

2) Add all the demineralized water and soybean protein powder into the reaction kettle equipped with agitator, thermometer and condensing device, and stir evenly;

3) Heat in a water bath to 70-75°C and react for 5 hours;

4) The temperature of the reactant is lowered to 30°C to obtain a uniform soy protein mucus;

5) Add the enhancer to the obtained soybean protein mucilage, mix well, and then add sodium benzoate to make the soybean protein adhesive.

Among them, the quality index of soybean protein adhesive is shown in Table 1.

Table 1 Performance index of soy protein adhesive

Experimental example

Three-layer plywood of 400×400 mm was manufactured by using the products of Examples 1-4 of the present invention and comparative examples (soybean protein mucilage in Examples 1-4 was used as an adhesive, as Comparative Examples 1-4).

Poplar veneer: dry to 10-14% moisture content; thickness 1.5mm;

The veneer adhesive used the products of Examples 1-4 of the present invention and the products of Comparative Examples 1-4.

Plywood is prepared according to the normal process as follows:

Glue sizing: Glue is applied on both sides of the core board, and the amount of glue applied is 310-330g/m ² ;

Aging method and time: closed aging, 20-30 minutes;

Pre-compression pressure and time: pre-compression 40 minutes, pressure 0.9MPa;

Hot pressing pressure: 1.0MPa, hot pressing temperature is 110-120°C, hot pressing time is 90s/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

Structural analysis: the above experimental results show that the formaldehyde emission of the plywood manufactured by the formaldehyde-free soy protein adhesive of the present invention is very low (for the formaldehyde released by the wood body), and the bonding strength of the plywood is above 1.05MPa, reaching the standard of Class II plywood in the national standard (Polar wood ≥ 0.70MPa).

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 2000-4000 yuan/ton, and the price of phenolic resin adhesive is 5000-6000 yuan/ton. The cost is about 3,000 yuan/ton, which is far lower than that of phenolic resin adhesives and close to that of modified urea-formaldehyde resin adhesives.

The adhesive prepared by the invention can replace the conventional formaldehyde-containing adhesive for plywood, 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 adhesive and far lower than the use cost of phenolic resin adhesive. Therefore, the soybean protein adhesive of the present invention has good application prospects.

In addition, the raw materials used in the present invention are commonly used raw materials in the production of this field, all of which can be obtained from the market, and will not affect the production results; the various equipment used in the present invention are all used in the production process of this field The conventional equipment, and the operation and parameters of each equipment are carried out according to the conventional operation, and there is nothing special about it.

Claims (2)

1. a kind of modified soy-bean protein base adhesive, it is characterised in that be prepared by the raw material of following parts by weight：

Decentralized medium 60-70 parts, degreasing legumin powder 20-35 parts, urea 0.5-2 parts, crosslinking enhancer 2-15 parts, sodium benzoate 1-8 parts；Wherein, the decentralized medium selection softened water；

The crosslinking enhancer is melamine-epoxychloropropane-sodium hydroxide reactant, and preparation method is：By 1mol trimerizations Cyanamide and 10mol water are placed in four-hole boiling flask constant temperature to 60 DEG C, and it is molten to add the sodium hydroxide of boron trifluoride 1% and 0.05mol, mixes 4mol epoxychloropropane monomer is slowly dropped into after closing uniformly to react 5 hours at 70-90 DEG C, after be cooled to 50 DEG C, add 0.15mol sodium hydroxides, stir 20 minutes, neutralize unnecessary alkali, be evaporated under reduced pressure free epoxychloropropane, refine in ethanol Drying obtains a kind of crosslinking enhancer of modified soy-bean protein base adhesive.

A kind of a kind of 2. preparation method of modified soy-bean protein base adhesive as claimed in claim 1, it is characterised in that including Following steps：

1）Each raw material is weighed according to above-mentioned weight proportion, degreasing legumin powder, urea is dispersed in decentralized medium；

2）Crosslinking enhancer, sodium benzoate are added, is stirred；

The crosslinking enhancer is melamine-epoxychloropropane-sodium hydroxide reactant；The decentralized medium selection softening Water；

The crosslinking enhancer is melamine-epoxychloropropane-sodium hydroxide reactant, and preparation method is：By 1mol trimerizations Cyanamide and 10mol water are placed in four-hole boiling flask constant temperature to 60 DEG C, and it is molten to add the sodium hydroxide of boron trifluoride 1% and 0.05mol, mixes 4mol epoxychloropropane monomer is slowly dropped into after closing uniformly to react 5 hours at 70-90 DEG C, after be cooled to 50 DEG C, add 0.15mol sodium hydroxides, stir 20 minutes, neutralize unnecessary alkali, be evaporated under reduced pressure free epoxychloropropane, refine in ethanol Drying obtains a kind of crosslinking enhancer of modified soy-bean protein base adhesive.