CN112300350B - Urea-formaldehyde resin adhesive modifier and application thereof, modified urea-formaldehyde resin adhesive and application thereof - Google Patents
Urea-formaldehyde resin adhesive modifier and application thereof, modified urea-formaldehyde resin adhesive and application thereof Download PDFInfo
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- CN112300350B CN112300350B CN202011300796.4A CN202011300796A CN112300350B CN 112300350 B CN112300350 B CN 112300350B CN 202011300796 A CN202011300796 A CN 202011300796A CN 112300350 B CN112300350 B CN 112300350B
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- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G12/00—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen
- C08G12/02—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes
- C08G12/40—Chemically modified polycondensates
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- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
- C09J161/00—Adhesives based on condensation polymers of aldehydes or ketones; Adhesives based on derivatives of such polymers
- C09J161/20—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen
- C09J161/32—Modified amine-aldehyde condensates
Abstract
The invention relates to the technical field of adhesives, in particular to a urea-formaldehyde resin adhesive modifier and application thereof, and a modified urea-formaldehyde resin adhesive and application thereof. The invention takes the degraded tannin with the molecular weight of 200-1000 Da as the main component of the urea-formaldehyde resin adhesive modifier, and because the degraded tannin has small molecular weight, more methyl activation centers are provided, and the reaction capability with the urea-formaldehyde resin is improved when the urea-formaldehyde resin is modified; meanwhile, the formaldehyde aqueous solution and the soluble aluminum salt are used as the cross-linking agent of the modifier system, so that the full reaction of the degraded tannin and the urea-formaldehyde resin can be further ensured, the modification effect is enhanced, and the modified urea-formaldehyde resin adhesive obtained after modification by the modifier has the characteristics of good water resistance, high bonding strength and small formaldehyde release amount.
Description
Technical Field
The invention relates to the technical field of adhesives, in particular to a urea-formaldehyde resin adhesive modifier and application thereof, and a modified urea-formaldehyde resin adhesive and application thereof.
Background
With the continuous decrease of forest resources and the development of economy, the production of global artificial boards is rapidly developed in recent years, and the demand of wood adhesives serving the artificial board industry is increased. The adhesive for the artificial board is mainly concentrated on phenolic aldehyde (PF) resin and urea-formaldehyde (UF) resin, PF has better water resistance than UF, but has higher cost, and UF resin is a main adhesive variety in the wood industry for a long time on the basis of the consideration of cost, and the using amount of the UF resin accounts for more than 70% of the adhesive amount in the whole wood industry.
However, unmodified UF resins have problems of poor water resistance and large formaldehyde emission. In view of better water resistance and strength of PF resin, the urea formaldehyde resin can be modified by phenol, but the cost is still higher. Because the biomass tannin raw material has a chemical structure similar to that of phenol, in order to further reduce the cost and improve the utilization rate of renewable resources, tannin can be considered to replace phenol to modify urea-formaldehyde resin.
Chinese patent publication No. CN01130562.2 discloses a method for directly adding condensed tannin to urea-formaldehyde resin to prepare a modified urea-formaldehyde resin adhesive; chinese patent with application number CN201310342111.6 discloses a preparation method and an application method of an adhesive of composite urea resin and bark powder, the bark powder is used as a main filler in the adhesive, and the bark powder is rich in condensed tannin components in a certain proportion. The two patents have the problems that the modified urea-formaldehyde resin has overlarge viscosity, is difficult to glue and has poor gluing performance when the condensed tannin is directly applied to UF resin.
Disclosure of Invention
In view of the above, the invention aims to provide a urea-formaldehyde resin adhesive modifier and application thereof, and a modified urea-formaldehyde resin adhesive and application thereof.
In order to achieve the purpose, the invention provides the following technical scheme:
the invention provides a urea-formaldehyde resin adhesive modifier which comprises the following preparation raw materials in parts by mass:
degraded tannin 15-42 weight portions;
5-20 parts of formaldehyde aqueous solution;
0.1-5 parts of soluble aluminum salt;
the molecular weight of the degraded tannin is 200-1000 Da; the mass concentration of formaldehyde in the formaldehyde aqueous solution is 20-38%.
Preferably, the preparation method of the degraded tannin comprises the following steps:
mixing the condensed tannin aqueous solution with tannin degrading bacteria, and performing biodegradation to obtain degraded tannin;
the pH value of the biodegradation is 3.0-7.0, and the temperature is 30-60 ℃.
Preferably, the mass concentration of the condensed tannin in the condensed tannin aqueous solution is 0.5-10%; the molecular weight of the condensed tannin is 500-5000 Da.
Preferably, the tannin degrading bacteria comprise one or more of bacillus subtilis, streptococcus and pseudomonas.
Preferably, the time of biodegradation is 1 to 7 days.
Preferably, the soluble aluminium salt comprises aluminium nitrate and/or aluminium sulphate.
The invention provides application of the urea-formaldehyde resin adhesive modifier in the technical scheme in the field of urea-formaldehyde resin adhesives.
The invention provides a modified urea-formaldehyde resin adhesive, which comprises urea-formaldehyde resin and a urea-formaldehyde resin adhesive modifier which are independently packaged; the mass ratio of the urea-formaldehyde resin to the urea-formaldehyde resin adhesive modifier is (99-70): (1-30);
the urea-formaldehyde resin adhesive modifier is the urea-formaldehyde resin adhesive modifier in the technical scheme.
The invention provides application of the modified urea-formaldehyde resin adhesive in the technical scheme in the field of artificial board adhesion.
Preferably, the glue application amount of the modified urea-formaldehyde resin adhesive in the artificial board is 80-140 g/m 2 ；
The application comprises hot pressing the glued plate, wherein the hot pressing temperature is 120-185 ℃, the pressure is 0.7-1.4 MPa, and the time is 3-7 min.
In order to achieve the purpose, the urea-formaldehyde resin adhesive modifier provided by the invention comprises the following preparation raw materials in parts by mass: 15-42 parts of degraded tannin; 5-20 parts of formaldehyde aqueous solution; 0.1-5 parts of soluble aluminum salt; the molecular weight of the degraded tannin is 200-1000 Da; the mass concentration of formaldehyde in the formaldehyde aqueous solution is 20-38%. The invention takes the degraded tannin with the molecular weight of 200-1000 Da as the main component of the urea-formaldehyde resin adhesive modifier, and because the degraded tannin has small molecular weight, more methyl activation centers are provided, and the reaction capability with the urea-formaldehyde resin is improved when the urea-formaldehyde resin is modified; the formaldehyde aqueous solution and the soluble aluminum salt are used as the cross-linking agents of the modifier system, wherein formaldehyde can perform substitution reaction with the ortho-position of the benzene ring hydroxyl in the degraded tannin structure, aluminum ions in the soluble aluminum salt can catalyze the ortho-position of the benzene ring hydroxyl of the degraded tannin to perform polycondensation, the condensation reaction can occur between the degraded and modified tannin or between the degraded and the urea-formaldehyde resin, and the two reactions can improve the bonding strength and the water resistance after curing, so that the modified urea-formaldehyde resin adhesive obtained after modification by the modifier has the characteristics of high bonding strength, small formaldehyde release amount, controllable viscosity and excellent operability. From the results of the examples, it is known that the bonding strength of the modified urea-formaldehyde resin adhesive prepared by using the urea-formaldehyde resin adhesive modifier of the invention in warm water at 63 ℃ is 1.28MPa, the bonding strength in boiling water is 0.56MPa, the bonding strength is high, the water resistance is good, and the formaldehyde emission is only 0.76mg/L.
The viscosity of the urea-formaldehyde resin adhesive modifier provided by the invention is 10.9 mPa.s, the viscosity of the urea-formaldehyde resin is 20-24 mPa.s, and when the urea-formaldehyde resin adhesive modifier is used for modifying the urea-formaldehyde resin adhesive, the viscosity of the modified urea-formaldehyde resin adhesive obtained by mixing the urea-formaldehyde resin adhesive modifier and the urea-formaldehyde resin adhesive is not immediately and greatly improved.
Detailed Description
The invention provides a urea-formaldehyde resin adhesive modifier which comprises the following preparation raw materials in parts by mass:
15-42 parts of degraded tannin;
5-20 parts of formaldehyde aqueous solution;
0.1-5 parts of soluble aluminum salt;
the molecular weight of the degraded tannin is 200-1000 Da; the mass concentration of formaldehyde in the formaldehyde aqueous solution is 20-38%.
In the present invention, all the raw materials are commercially available products unless otherwise specified.
The urea-formaldehyde resin adhesive modifier comprises, by mass, 15-42 parts of degraded tannin, preferably 20-38 parts, and more preferably 25-30 parts; in the present invention, the molecular weight of the degraded tannin is 200 to 1000Da, preferably 220 to 600Da, more preferably 250 to 450Da. In the present invention, the degraded tannin is preferably an aqueous degraded tannin solution, and the solid content of the aqueous degraded tannin solution is preferably 20 to 70%, more preferably 25 to 60%, and most preferably 30 to 45%.
In the present invention, the degraded tannin is preferably obtained by a method of preparation, which preferably comprises the steps of:
mixing the condensed tannin water solution with tannin degrading bacteria, and performing biodegradation to obtain degraded tannin;
the pH value of the biodegradation is 3.0-7.0, and the temperature is 30-60 ℃.
In the present invention, the concentration by mass of the condensed tannin in the aqueous solution of the condensed tannin is preferably 0.5 to 10%, more preferably 1 to 8%, and the molecular weight of the condensed tannin is preferably 500 to 5000Da, more preferably 650 to 4500Da. In the present invention, the tannin degrading bacteria preferably include Bacillus subtilis, streptococcus or Pseudomonas. In the invention, the tannin degrading bacteria need to be activated or rejuvenated before being used, the activation temperature is preferably 37 ℃, and the specific implementation process of the activation and the rejuvenation is not particularly required and can be carried out by adopting a mode well known by a person skilled in the art. In the present invention, the tannin degrading bacteria are used in the form of an aqueous tannin degrading bacteria solution, and in the present invention, the mixing is preferably performed by adding an aqueous tannin degrading bacteria solution to the aqueous condensed tannin solution, and the mass ratio of the aqueous condensed tannin solution to the aqueous tannin degrading bacteria solution is preferably 10.
In the present invention, the mixing is preferably performed by adding tannin degrading bacteria to the condensed tannin aqueous solution.
In the present invention, the pH of the biodegradation is 3.0 to 7.0, preferably 3.5 to 6.5, more preferably 4.0 to 5.0; the temperature is 30-60 ℃, preferably 35-50 ℃, and more preferably 30-40 ℃; the time is preferably 1 to 7 days, more preferably 3 days. In the present invention, the pH value of the biodegradation is preferably adjusted by a pH adjusting agent, the pH adjusting agent preferably comprises 0.5mol/L NaOH solution or 0.5mol/L HCl solution, and in the present invention, the pH value of the biodegradation is the pH value of a mixed solution obtained by mixing the condensed tannin aqueous solution and the tannin degrading bacteria aqueous solution. In the invention, the biodegradation is preferably carried out under the condition of shaking or stirring, when the biodegradation is carried out at the laboratory level, the biodegradation is preferably carried out under the condition of shaking, the concrete operation of shaking is not particularly required, and the operation well known by the technical personnel in the field can be adopted; when the present invention is used for industrial-scale biodegradation, the present invention is preferably carried out under stirring, preferably mechanical stirring, at a speed of preferably 30 to 200r/min, more preferably 60 to 150r/min.
After the biodegradation is finished, the invention preferably carries out post-treatment on the biodegradable product to obtain the degraded tannin aqueous solution, and the solid content of the degraded tannin aqueous solution is preferably 20-70%. In the invention, the post-treatment preferably comprises concentration, in the invention, the concentration mode is preferably reduced pressure distillation, the temperature of the reduced pressure distillation is preferably 90 ℃, and the time and the pressure of the reduced pressure distillation are not particularly required so as to realize the concentration of the solid content of the degraded tannin aqueous solution to be 20-70%.
Based on degraded tannin, the urea-formaldehyde resin adhesive modifier provided by the invention comprises 5-20 parts of formaldehyde aqueous solution, preferably 6-18 parts, more preferably 7.5-15 parts; in the present invention, the mass concentration of formaldehyde in the aqueous formaldehyde solution is 20 to 38%, preferably 37%.
Based on degraded tannin, the urea-formaldehyde resin adhesive modifier provided by the invention comprises 0.1-5 parts of soluble aluminum salt, preferably 0.5-4 parts, more preferably 1.5-3.5 parts; in the present invention, the soluble aluminum salt preferably includes aluminum nitrate and/or aluminum sulfate, more preferably includes aluminum nitrate and aluminum sulfate, and in the present invention, when the soluble aluminum salt includes aluminum nitrate and aluminum sulfate, the mass ratio of aluminum nitrate and aluminum sulfate is preferably 1: (0.5-2).
In the invention, the formaldehyde in the formaldehyde aqueous solution can perform substitution reaction with the ortho position of the benzene ring hydroxyl in the degraded tannin structure to generate micromolecular hydroxymethylated tannin; aluminum ions in the soluble aluminum salt can catalyze the ortho-position of benzene ring hydroxyl of the degraded tannin to perform condensation polymerization, the condensation reaction can occur between the degraded modified tannin or between the degraded modified tannin and urea resin, and the substitution reaction and the polymerization reaction can improve the bonding strength and the water resistance after curing.
In the present invention, the preparation method of the urea-formaldehyde resin adhesive modifier preferably comprises the following steps:
and mixing the degraded tannin, the formaldehyde aqueous solution and the soluble aluminum salt to obtain the urea-formaldehyde resin adhesive modifier.
In the invention, the degraded tannin is preferably prepared by the preparation method of the degraded tannin according to the above technical scheme, and details are not repeated herein.
In the present invention, the mixing preferably comprises the steps of: carrying out first mixing on the degraded tannin and a formaldehyde aqueous solution to obtain a formaldehyde modified tannin aqueous solution; and adding soluble aluminum salt into the formaldehyde modified tannin aqueous solution to obtain the urea-formaldehyde resin adhesive modifier.
In the present invention, the first mixing and the second mixing are preferably carried out under stirring conditions, the stirring rate is preferably 40 to 300r/min, more preferably 80 to 200r/min, independently, and the temperature is preferably 15 to 35 ℃, more preferably 25 ℃ independently. The invention has no special requirement on the time of the first mixing and the second mixing so as to realize uniform mixing.
In the invention, in the first mixing process, the formaldehyde in the formaldehyde aqueous solution can perform substitution reaction with the ortho position of the benzene ring hydroxyl in the degraded tannin structure to form micromolecular hydroxymethylated tannin; aluminum ions in the soluble aluminum salt after the second mixing can catalyze the ortho-position of benzene ring hydroxyl of the degraded tannin to perform condensation polymerization, the condensation reaction can occur between the degraded and modified tannins or between the degraded and modified tannins and urea resin, and the crosslinking reaction can improve the bonding strength and the water resistance after curing.
The storage time of the urea-formaldehyde resin adhesive modifier prepared by the invention is less than or equal to 2 days.
The invention also provides the application of the urea-formaldehyde resin adhesive modifier in the urea-formaldehyde resin adhesive.
The invention provides a modified urea-formaldehyde resin adhesive, which comprises a urea-formaldehyde resin and a urea-formaldehyde resin adhesive modifier which are independently packaged; the mass ratio of the urea-formaldehyde resin to the urea-formaldehyde resin adhesive modifier is (70-99): (1-30);
the urea-formaldehyde resin adhesive modifier is the urea-formaldehyde resin adhesive modifier in the technical scheme.
The modified urea-formaldehyde resin adhesive provided by the invention comprises 70-99 parts of urea-formaldehyde resin by mass, and preferably 75-90 parts of urea-formaldehyde resin by mass.
In the present invention, the urea-formaldehyde resin is preferably obtained by a method of preparation, which preferably comprises the steps of:
carrying out first mixing on a formaldehyde solution, a first batch of urea and melamine to carry out first polycondensation reaction to obtain a first-grade product;
carrying out second mixing on the primary product and a second batch of urea to carry out second polycondensation reaction to obtain a secondary product;
and carrying out third mixing on the secondary product and a third batch of urea to carry out a third polycondensation reaction to obtain the urea-formaldehyde resin.
The method comprises the steps of carrying out a first mixing condensation polymerization reaction on a formaldehyde solution, a first batch of urea and melamine to obtain a first-grade product; in the present invention, the mass content of formaldehyde in the formaldehyde solution is preferably 38%, and the molar ratio of the first urea to the formaldehyde in the formaldehyde solution is preferably 1:2, the mass ratio of the first batch of urea to melamine is preferably 1. In the present invention, the temperature of the first mixing is preferably 50 ℃ and the time is preferably 30min; the pH value of the mixed solution obtained after the first mixing is preferably 8.0, the pH value of the mixed solution is preferably adjusted by adopting a pH value adjusting agent, the pH value adjusting agent is preferably NaOH solution, and the invention has no special requirement on the mass concentration of the NaOH solution.
After a first-stage product is obtained, carrying out second mixing on the first-stage product and a second batch of urea to carry out polycondensation reaction, and obtaining a second-stage product; in the present invention, the molar ratio of the total mass of the second batch of urea and the first batch of urea to the formaldehyde in the formaldehyde solution is preferably 1.4, and in the present invention, the temperature of the second mixing is preferably 90 ℃ and the time is preferably 55min; the pH of the mixed solution obtained after the second mixing is preferably 5.4-5.6, the pH of the mixed solution is preferably adjusted by adopting a pH adjusting agent, the pH adjusting agent is preferably formic acid solution, and the invention has no special requirement on the mass concentration of the formic acid solution.
After a secondary product is obtained, the secondary product and a third batch of urea are subjected to third mixing to perform polycondensation reaction, and the urea-formaldehyde resin is obtained. In the present invention, the molar ratio of the total mass of the third batch of urea, the second batch of urea and the first batch of urea to the formaldehyde in the formaldehyde solution is preferably 1.05, and in the present invention, the temperature of the third mixing is preferably 65-70 ℃ and the time is preferably 30min; the pH of the mixed solution obtained after the third mixing is preferably 7.5-8.0, the pH of the mixed solution is preferably adjusted by adopting a pH adjusting agent, the pH adjusting agent is preferably NaOH solution, and the invention has no special requirement on the mass concentration of the NaOH solution.
In the invention, after the third mixing is finished, the temperature of the reaction system is preferably reduced, the temperature after the temperature reduction is preferably 30 ℃, then the material is discharged after the pH value of the material is preferably 8.0, the pH value is preferably adjusted by adopting a pH adjusting agent, the pH adjusting agent is preferably NaOH solution, and the invention has no special requirement on the mass concentration of the NaOH solution.
Based on urea-formaldehyde resin, the modified urea-formaldehyde resin provided by the invention comprises 1-30 parts of urea-formaldehyde resin adhesive modifier, preferably 10-25 parts. In the invention, the urea-formaldehyde resin adhesive modifier is the urea-formaldehyde resin adhesive modifier in the technical scheme.
In the invention, the modified urea-formaldehyde resin adhesive is prepared in situ, and the preparation method is preferably as follows: the urea-formaldehyde resin adhesive and the urea-formaldehyde resin adhesive modifier are directly mixed.
The invention also provides the application of the modified urea-formaldehyde resin adhesive in the technical scheme in the field of artificial board bonding.
In the invention, the application method of the modified urea-formaldehyde resin adhesive in the field of artificial board adhesion preferably comprises the steps of coating, assembling and hot pressing in sequence. In the invention, the gluing amount of the modified urea-formaldehyde resin adhesive in the artificial board during coating is preferably 80-140 g/m 2 More preferably 120g/m 2 The hot pressing temperature is preferably 120 to 185 ℃, more preferably 145 ℃, the pressure is preferably 0.7 to 1.4MPa, more preferably 1MPa, and the time is preferably 3 to 7min, more preferably 5min. In the specific embodiment of the invention, the artificial board obtained by bonding the modified urea-formaldehyde resin adhesive is a three-layer board with the thickness of 3mm.
In order to better understand the present invention, the following examples are further provided to illustrate the present invention, but the present invention is not limited to the following examples.
Example 1
Adding 10g of activated and 2-3-generation rejuvenated bacillus subtilis-containing aqueous solution into 100g of condensed tannin (molecular weight is 500-5000 Da) aqueous solution with the mass concentration of 10%, reacting for 5 days at the pH value of 3.0 and the temperature of 50 ℃, and distilling under reduced pressure to obtain degraded tannin aqueous solution with the solid content of 40%, wherein the molecular weight of the degraded tannin is 200-1000 Da;
adding 5g of formaldehyde aqueous solution with the mass concentration of 37% into 80g of degraded tannin aqueous solution with the solid content of 40% at 25 ℃, uniformly stirring at 300r/min, adding 1g of aluminum sulfate, and continuously uniformly stirring to obtain the urea-formaldehyde resin adhesive modifier;
adding 60g of formaldehyde solution into a three-neck flask, heating to 50 ℃, adjusting the pH to 8.0 by using NaOH solution, adding 22.2g of first batch of urea and 1.11g of melamine, and reacting for 30min; heating to 90 ℃, adjusting the pH value to 5.6 by using a formic acid solution, adding 9.5g of second batch of urea, and reacting for 55min; adjusting the pH value to 8.0 by using NaOH solution, adding 10.58g of third batch of urea, and enabling the molar ratio of formaldehyde to urea to be 1.05:1, cooling to 70 ℃, carrying out heat preservation reaction for 30min, cooling to 30 ℃, finally adjusting the pH to 8.0 by using a NaOH solution, and discharging to obtain urea-formaldehyde resin;
mixing 80g of urea-formaldehyde resin and 20g of urea-formaldehyde resin adhesive modifier, coating the mixture on the surface of a plate material, and performing hot pressing according to the following parameters: the glue application amount is 120g/m 2 The temperature is 145 ℃, and the pressure is 1MPa. Hot pressing for 5min to obtain three-layer board with thickness of 3mm.
Example 2
Adding 10g of conventionally activated and 2-3-generation rejuvenated bacillus subtilis-containing aqueous solution into 100g of condensed tannin (molecular weight is 500-5000 Da) aqueous solution with mass concentration of 10%, reacting for 5 days at the pH value of 3.0 and the temperature of 50 ℃, and distilling under reduced pressure to obtain degraded tannin aqueous solution with 40% of solid content, wherein the molecular weight of the degraded tannin is 200-1000 Da;
at 25 ℃, adding 5g of 37 percent formaldehyde aqueous solution into 80g of degraded tannin aqueous solution with the solid content of 40 percent, stirring uniformly at 300r/min, adding 0.5g of aluminum sulfate and 0.5g of aluminum nitrate, and continuously stirring uniformly to obtain the urea-formaldehyde resin adhesive modifier;
adding 60g of formaldehyde solution into a three-neck flask, heating to 50 ℃, adjusting the pH to 8.0 by using NaOH solution, adding 22.2g of first batch of urea and 1.11g of melamine, and reacting for 30min; heating to 90 ℃, adjusting the pH value to 5.6 by using a formic acid solution, adding 9.5g of second batch of urea, and reacting for 55min; adjusting the pH value to 8.0 by using NaOH solution, adding 10.58g of third batch of urea to ensure that the molar ratio of formaldehyde to urea is 1.05:1, cooling to 70 ℃, carrying out heat preservation reaction for 30min, cooling to 30 ℃, finally adjusting the pH to 8.0 by using a NaOH solution, and discharging to obtain urea-formaldehyde resin;
mixing 80g of urea-formaldehyde resin and 20g of urea-formaldehyde resin adhesive modifier, coating the mixture on the surface of a plate material, and performing hot pressing according to the following parameters: the glue application amount is 120g/m 2 The temperature is 145 ℃, and the pressure is 1MPa. Hot pressing for 5min to obtainThe artificial board is a three-layer board with the thickness of 3mm.
Example 3
Adding 10g of conventionally activated and 2-3 generations of rejuvenated bacillus licheniformis bacteria aqueous solution into 100g of condensed tannin (molecular weight is 500-5000 Da) aqueous solution with mass concentration of 10%, reacting for 5 days under the conditions of pH value of 3.0 and temperature of 37 ℃, and distilling under reduced pressure to obtain degraded tannin aqueous solution with 40% of solid content, wherein the molecular weight of the degraded tannin is 300-3500 Da;
at 25 ℃, adding 5g of 37 percent formaldehyde water solution into 80g of degraded tannin water solution with the solid content of 40 percent, uniformly stirring at 300r/min, adding 1g of aluminum sulfate, and continuously uniformly stirring to obtain the urea-formaldehyde resin adhesive modifier;
adding 60g of formaldehyde solution into a three-neck flask, heating to 50 ℃, adjusting the pH to 8.0 by using NaOH solution, adding 22.2g of first batch of urea and 1.11g of melamine, and reacting for 30min; heating to 90 ℃, adjusting the pH value to 5.6 by using a formic acid solution, adding 9.5g of second batch of urea, and reacting for 55min; adjusting the pH value to 8.0 by using NaOH solution, adding 10.58g of third batch of urea to ensure that the molar ratio of formaldehyde to urea is 1.05:1, cooling to 70 ℃, carrying out heat preservation reaction for 30min, cooling to 30 ℃, finally adjusting the pH to 8.0 by using a NaOH solution, and discharging to obtain urea-formaldehyde resin;
mixing 80g of urea-formaldehyde resin and 20g of urea-formaldehyde resin adhesive modifier, coating the mixture on the surface of a plate material, and performing hot pressing according to the following parameters: the glue application amount is 120g/m 2 The temperature is 145 ℃, and the pressure is 1MPa. Hot pressing for 5min to obtain a three-layer board with a thickness of 3mm.
Example 4
Adding 10g of conventionally activated and 2-3 generations rejuvenated bacillus subtilis-containing aqueous solution into 100g of condensed tannin (molecular weight is 500-5000 Da) aqueous solution with mass concentration of 10%, reacting for 5 days under the conditions of pH value of 3.0 and temperature of 50 ℃, and distilling under reduced pressure to obtain 40% solid content degraded tannin aqueous solution, wherein the molecular weight of the degraded tannin is 200-1000 Da;
at 25 ℃, adding 5g of 37 percent formaldehyde water solution into 80g of degraded tannin water solution with the solid content of 40 percent, uniformly stirring at 300r/min, adding 1g of aluminum sulfate, and continuously uniformly stirring to obtain the urea-formaldehyde resin adhesive modifier;
adding 60g of formaldehyde solution into a three-neck flask, heating to 50 ℃, adjusting the pH to 8.0 by using NaOH solution, adding 22.2g of first batch of urea and 1.11g of melamine, and reacting for 30min; heating to 90 ℃, adjusting the pH value to 5.4 by using a formic acid solution, adding 9.5g of second batch of urea, and reacting for 55min; adjusting the pH value to 8.0 by using NaOH solution, adding 10.58g of third batch of urea to ensure that the molar ratio of formaldehyde to urea is 1.05:1, cooling to 70 ℃, carrying out heat preservation reaction for 30min, cooling to 30 ℃, finally adjusting the pH to 8.0 by using a NaOH solution, and discharging to obtain urea-formaldehyde resin;
mixing 90g of urea-formaldehyde resin and 10g of urea-formaldehyde resin adhesive modifier, coating the mixture on the surface of a plate material, and performing hot pressing according to the following parameters: the glue application amount is 120g/m 2 The temperature is 145 ℃, and the pressure is 1MPa. Hot pressing for 5min to obtain three-layer board with thickness of 3mm.
Example 5
Adding 10g of conventionally activated and 2-3 generations rejuvenated bacillus subtilis-containing aqueous solution into 100g of condensed tannin (molecular weight is 500-5000 Da) aqueous solution with mass concentration of 10%, reacting for 5 days under the conditions of pH value of 3.0 and temperature of 50 ℃, and distilling under reduced pressure to obtain 40% solid content degraded tannin aqueous solution, wherein the molecular weight of the degraded tannin is 200-1000 Da;
at 25 ℃, adding 5g of 37 percent formaldehyde aqueous solution into 80g of degraded tannin aqueous solution with the solid content of 40 percent, stirring uniformly at 300r/min, adding 0.5g of aluminum sulfate and 0.5g of aluminum nitrate, and continuously stirring uniformly to obtain the urea-formaldehyde resin adhesive modifier;
adding 60g of formaldehyde solution into a three-neck flask, heating to 50 ℃, adjusting the pH to 8.0 by using NaOH solution, adding 22.2g of first batch of urea and 1.11g of melamine, and reacting for 30min; heating to 90 ℃, adjusting the pH value to 5.6 by using a formic acid solution, adding 9.5g of second batch of urea, and reacting for 55min; adjusting the pH value to 8.0 by using NaOH solution, adding 10.58g of third batch of urea to ensure that the molar ratio of formaldehyde to urea is 1.05:1, cooling to 70 ℃, carrying out heat preservation reaction for 30min, cooling to 30 ℃, finally adjusting the pH to 8.0 by using a NaOH solution, and discharging to obtain urea-formaldehyde resin;
70g of urea-formaldehyde resin and 30g of urea-formaldehyde resin adhesive modifier are mixed and coated on the surface of a plate material, and the hot pressing process parameters are as follows: the glue application amount is 120g/m 2 The temperature is 145 ℃, and the pressure is 1MPa. Hot pressing for 5min to obtain a three-layer board with a thickness of 3mm.
Comparative example 1
Adding 60g of formaldehyde solution into a three-neck flask, heating to 50 ℃, adjusting the pH to 8.0 by using NaOH solution, adding 22.2g of first batch of urea and 1.11g of melamine, and reacting for 30min; heating to 90 ℃, adjusting the pH value to 5.4-5.6 by using a formic acid solution, adding 9.5g of second batch of urea, and reacting for 55min; adjusting the pH value to 8.0 by using NaOH solution, adding 10.58g of third batch of urea to ensure that the molar ratio of formaldehyde to urea is 1.05:1, cooling to 70 ℃, carrying out heat preservation reaction for 30min, cooling to 30 ℃, finally adjusting the pH to 8.0 by using a NaOH solution, and discharging to obtain urea-formaldehyde resin;
coating the urea-formaldehyde resin on the surface of a plate material according to thermal coating, and performing hot pressing according to the following technological parameters: the glue application amount is 120g/m 2 Hot pressing at 145 ℃ and 1MPa for 5min to obtain the artificial board with a thickness of 3mm.
Comparative example 2
Adding 60g of formaldehyde solution into a three-neck flask, heating to 50 ℃, adjusting the pH to 8.0 by using NaOH solution, adding 22.2g of first batch of urea and 1.11g of melamine, and reacting for 30min; heating to 90 ℃, adjusting the pH value to 5.4-5.6 by using a formic acid solution, adding 9.5g of second batch of urea, and reacting for 55min; adjusting the pH value to 8.0 by using NaOH solution, adding 10.58g of third batch of urea to ensure that the molar ratio of formaldehyde to urea is 1.05:1, cooling to 70 ℃, carrying out heat preservation reaction for 30min, cooling to 30 ℃, finally adjusting the pH to 8.0 by using a NaOH solution, and discharging to obtain urea-formaldehyde resin;
adding the urea-formaldehyde resin adhesive into aluminum sulfate with the weight of 1% of the adhesive, and performing hot pressing according to the following parameters: the glue application amount is 120g/m 2 The temperature is 145 ℃, and the pressure is 1MPa. Hot pressing for 5 minutes to obtain a developed three-layer plate, wherein the thickness of a finished product is 3mm.
Comparative example 3
Adding 60g of formaldehyde solution into a three-neck flask, heating to 50 ℃, adjusting the pH to 8.0 by using NaOH solution, adding 22.2g of first batch of urea and 1.11g of melamine, and reacting for 30min; heating to 90 ℃, adjusting the pH value to 5.4-5.6 by using a formic acid solution, adding 9.5g of second batch of urea, and reacting for 55min; adjusting the pH value to 8.0 by using NaOH solution, adding 10.58g of third batch of urea to ensure that the molar ratio of formaldehyde to urea is 1.05:1, cooling to 70 ℃, carrying out heat preservation reaction for 30min, cooling to 30 ℃, finally adjusting the pH to 8.0 by using a NaOH solution, and discharging to obtain urea-formaldehyde resin;
adding a urea-formaldehyde resin adhesive into a condensed tannin aqueous solution with the adhesive weight of 20%, wherein the solid content is 40%, and the hot pressing process parameters are as follows: the glue application amount is 120g/m 2 The temperature is 145 ℃, and the pressure is 1MPa. Hot pressing for 5min to obtain three-layer plate with thickness of 3mm.
Comparative example 4
Adding 60g of formaldehyde solution into a three-neck flask, heating to 50 ℃, adjusting the pH to 8.0 by using NaOH solution, adding 22.2g of first batch of urea and 1.11g of melamine, and reacting for 30min; heating to 90 ℃, adjusting the pH value to 5.4-5.6 by using a formic acid solution, adding 9.5g of second batch of urea, and reacting for 55min; adjusting the pH value to 8.0 by using NaOH solution, adding 10.58g of third batch of urea to ensure that the molar ratio of formaldehyde to urea is 1.05:1, cooling to 70 ℃, carrying out heat preservation reaction for 30min, cooling to 30 ℃, finally adjusting the pH to 8.0 by using a NaOH solution, and discharging to obtain urea-formaldehyde resin;
adding a urea-formaldehyde resin adhesive into a condensed tannin aqueous solution with the weight of 20% of the adhesive, wherein the solid content is 40%, and simultaneously adding aluminum sulfate with the weight of 1% of the adhesive, and then performing hot pressing according to the following technological parameters: the glue application amount is 120g/m 2 The temperature is 145 ℃, and the pressure is 1MPa. Hot pressing for 5min to obtain three-layer plate with thickness of 3mm.
Test example
The performance of the artificial boards prepared in the examples 1 to 4 and the comparative examples 1 to 4 is tested by referring to the test method in GB/T17657-2013, and the results are shown in Table 1, and the test results in Table 1 show that the artificial boards obtained by gluing the modified urea-formaldehyde resin adhesive provided in the examples 1 to 4 have better gluing strength both in warm water and in boiling water, which indicates that the modified urea-formaldehyde resin adhesive provided by the invention has good water resistance, and the formaldehyde emission is obviously reduced compared with the comparative examples 1 to 4. Among them, from the results of comparative examples 1 and 2, it is known that the adhesive strength and formaldehyde emission in warm water are not substantially changed but the adhesive strength in boiling water is remarkably improved by adding aluminum sulfate alone, mainly because in boiling water, due to the high temperature, the hydrolysis of aluminum sulfate is enhanced and the formed aluminum hydroxide colloid plays a certain role as a binder; in the comparative example 3, the condensed tannin is directly used for modifying the urea-formaldehyde resin adhesive, the tannin is not degraded or modified, the viscosity of the obtained modified urea-formaldehyde resin adhesive is rapidly increased within 3 to 5 hours when the modified urea-formaldehyde resin adhesive is placed at the normal temperature of 25 ℃, the glue is not easily applied, the glue spraying pipeline is easily blocked, even if the modified urea-formaldehyde resin adhesive is applied within 5 minutes after mixing, the gluing performance in warm water is not increased but reduced, and the gluing performance is influenced mainly because the polymerization degree of the condensed tannin is too high, so that the polymerization of the artificial board during hot-pressing curing is influenced, and the viscosity is rapidly increased and the glue can not be applied after the urea-formaldehyde resin adhesive common to the condensed tannin and the aluminum sulfate is adopted for modification in the comparative example 4.
TABLE 1 Properties of Artificial boards obtained in examples 1 to 4 and comparative examples 1 to 4
The foregoing is merely a preferred embodiment of the invention and is not intended to limit the invention in any manner. It should be noted that, for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be construed as the protection scope of the present invention.
Claims (10)
1. The urea-formaldehyde resin adhesive modifier is characterized by comprising the following preparation raw materials in parts by mass:
15-42 parts of degraded tannin;
5-20 parts of formaldehyde aqueous solution;
0.1-5 parts of soluble aluminum salt;
the molecular weight of the degraded tannin is 200-1000 Da; the mass concentration of formaldehyde in the formaldehyde aqueous solution is 20-38%.
2. The urea-formaldehyde resin adhesive modifier according to claim 1, wherein the preparation method of the degraded tannin comprises the following steps:
mixing the condensed tannin water solution with tannin degrading bacteria, and performing biodegradation to obtain degraded tannin;
the pH value of the biodegradation is 3.0-7.0, and the temperature is 30-60 ℃.
3. The urea-formaldehyde resin adhesive modifier of claim 2, wherein the mass concentration of condensed tannin in the condensed tannin aqueous solution is 0.5-10%; the molecular weight of the condensed tannin is 500-5000 Da.
4. The urea-formaldehyde resin adhesive modifier of claim 2, wherein the tannin-degrading bacteria comprise one or more of bacillus subtilis, streptococcus, and pseudomonas.
5. The urea-formaldehyde resin adhesive modifier according to claim 2 or 4, wherein the biodegradation is carried out for 1 to 7 days.
6. The urea-formaldehyde resin adhesive modifier of claim 1, wherein the soluble aluminum salt comprises aluminum nitrate and/or aluminum sulfate.
7. Use of the urea formaldehyde resin adhesive modifier of any one of claims 1 to 6 in a urea formaldehyde resin adhesive.
8. A modified urea-formaldehyde resin adhesive is characterized by comprising urea-formaldehyde resin and a urea-formaldehyde resin adhesive modifier which are independently packaged; the mass ratio of the urea-formaldehyde resin to the urea-formaldehyde resin adhesive modifier is (99-70): (1-30);
the urea-formaldehyde resin adhesive modifier is the urea-formaldehyde resin adhesive modifier of any one of claims 1 to 6.
9. The use of the modified urea formaldehyde resin adhesive of claim 8 for bonding artificial panels.
10. The application of claim 9, wherein the amount of the modified urea-formaldehyde resin adhesive applied to the artificial board is 80-140 g/m 2 (ii) a The application comprises hot pressing the glued plate, wherein the hot pressing temperature is 120-185 ℃, the pressure is 0.7-1.4 MPa, and the time is 3-7 min.
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