CN102086257B - Environment-friendly urea resin for laminating plywoods from high water-content veneers and preparation and application thereof - Google Patents
Environment-friendly urea resin for laminating plywoods from high water-content veneers and preparation and application thereof Download PDFInfo
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- 229920001807 Urea-formaldehyde Polymers 0.000 title claims abstract description 37
- 238000002360 preparation method Methods 0.000 title claims abstract description 8
- 239000011120 plywood Substances 0.000 title abstract description 12
- 238000010030 laminating Methods 0.000 title abstract 2
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 claims abstract description 191
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims abstract description 50
- 239000004202 carbamide Substances 0.000 claims abstract description 50
- 238000000034 method Methods 0.000 claims abstract description 31
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 12
- 239000004372 Polyvinyl alcohol Substances 0.000 claims abstract description 9
- 229920002451 polyvinyl alcohol Polymers 0.000 claims abstract description 9
- 235000011114 ammonium hydroxide Nutrition 0.000 claims abstract description 8
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 39
- 238000012546 transfer Methods 0.000 claims description 37
- GZCGUPFRVQAUEE-SLPGGIOYSA-N aldehydo-D-glucose Chemical compound OC[C@@H](O)[C@@H](O)[C@H](O)[C@@H](O)C=O GZCGUPFRVQAUEE-SLPGGIOYSA-N 0.000 claims description 31
- 238000006243 chemical reaction Methods 0.000 claims description 19
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 claims description 18
- 231100000331 toxic Toxicity 0.000 claims description 12
- 230000002588 toxic effect Effects 0.000 claims description 12
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 claims description 9
- 239000008098 formaldehyde solution Substances 0.000 claims description 9
- 235000019253 formic acid Nutrition 0.000 claims description 9
- XZMCDFZZKTWFGF-UHFFFAOYSA-N Cyanamide Chemical compound NC#N XZMCDFZZKTWFGF-UHFFFAOYSA-N 0.000 claims description 7
- 238000010792 warming Methods 0.000 claims description 6
- 239000003513 alkali Substances 0.000 claims description 5
- 238000007599 discharging Methods 0.000 claims description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 4
- BAVYZALUXZFZLV-UHFFFAOYSA-N Methylamine Chemical compound NC BAVYZALUXZFZLV-UHFFFAOYSA-N 0.000 claims description 4
- 238000001816 cooling Methods 0.000 claims description 3
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 claims description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 2
- 239000002253 acid Substances 0.000 claims description 2
- 238000005352 clarification Methods 0.000 claims description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 claims description 2
- 229910017604 nitric acid Inorganic materials 0.000 claims description 2
- 238000003756 stirring Methods 0.000 claims description 2
- 229920005989 resin Polymers 0.000 abstract description 23
- 239000011347 resin Substances 0.000 abstract description 23
- 238000003786 synthesis reaction Methods 0.000 abstract description 6
- 230000015572 biosynthetic process Effects 0.000 abstract description 5
- 238000004132 cross linking Methods 0.000 abstract description 4
- 230000008569 process Effects 0.000 abstract description 4
- 230000007613 environmental effect Effects 0.000 abstract description 3
- JYEUMXHLPRZUAT-UHFFFAOYSA-N 1,2,3-triazine Chemical class C1=CN=NN=C1 JYEUMXHLPRZUAT-UHFFFAOYSA-N 0.000 abstract description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 abstract 2
- 229920000877 Melamine resin Polymers 0.000 abstract 1
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 abstract 1
- 230000002194 synthesizing effect Effects 0.000 abstract 1
- 235000019256 formaldehyde Nutrition 0.000 description 56
- 229960004279 formaldehyde Drugs 0.000 description 36
- 238000012360 testing method Methods 0.000 description 28
- 239000002023 wood Substances 0.000 description 23
- 230000000052 comparative effect Effects 0.000 description 12
- 239000003292 glue Substances 0.000 description 9
- 238000004519 manufacturing process Methods 0.000 description 9
- 239000003795 chemical substances by application Substances 0.000 description 8
- 239000002994 raw material Substances 0.000 description 7
- 230000000694 effects Effects 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 5
- 238000009413 insulation Methods 0.000 description 5
- 238000003860 storage Methods 0.000 description 5
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical class OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 4
- 239000000853 adhesive Substances 0.000 description 4
- 230000001070 adhesive effect Effects 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- 238000010998 test method Methods 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- ODGAOXROABLFNM-UHFFFAOYSA-N polynoxylin Chemical compound O=C.NC(N)=O ODGAOXROABLFNM-UHFFFAOYSA-N 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- 244000166124 Eucalyptus globulus Species 0.000 description 2
- 238000004026 adhesive bonding Methods 0.000 description 2
- 235000019270 ammonium chloride Nutrition 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 235000013312 flour Nutrition 0.000 description 2
- 230000036541 health Effects 0.000 description 2
- -1 methylols Chemical class 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 238000007711 solidification Methods 0.000 description 2
- 230000008023 solidification Effects 0.000 description 2
- 244000025254 Cannabis sativa Species 0.000 description 1
- 241000220317 Rosa Species 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 238000003915 air pollution Methods 0.000 description 1
- 150000001299 aldehydes Chemical class 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 235000012538 ammonium bicarbonate Nutrition 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 230000008676 import Effects 0.000 description 1
- 231100000053 low toxicity Toxicity 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000008447 perception Effects 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 238000006068 polycondensation reaction Methods 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
Landscapes
- Chemical And Physical Treatments For Wood And The Like (AREA)
- Phenolic Resins Or Amino Resins (AREA)
Abstract
The invention relates to a preparation method and application of environment-friendly urea resin for laminating plywoods from high water-content veneers. The method for synthesizing the resin is simple, and low in cost; the laminated plywoods can meet the national E1 grade and even E0 grade environmental protection requirements; and the problems of low prepressing performance and water resistance when the high water-content veneers are laminated into the plywoods are mainly solved. In the synthesis of the urea resin, an acid-base-acid-base process is adopted, formaldehyde and polyvinyl alcohol are added at one time, urea is added by three batches, melamine is added by two times, and after ammonia water is added, the ammonia water, the urea, the formaldehyde and urea-form condensate are reacted to generate a series of triazine ring compounds, and the microstructure of the resin is improved. When the resin is cured, the crosslinking density is improved, wet shear strength of the plywoods is obviously improved and the formaldehyde emission is obviously reduced.
Description
Technical field
The present invention relates to a kind of low toxic and environment-friendly urea-formaldehyde resin and preparation method thereof, particularly plywood production belongs to the adhesive of artificial board field with environment-friendly urea-formaldehyde resin and preparation method thereof.
Background technology
Wood veneer is owing to its excellent property, be convenient to processing, moderate and kept characteristics such as timber native texture and quality, and the green grass or young crops that always receives people is paid attention to, and is that exploitation is the earliest and the traditional product that Chang Sheng does not wane in the wood-base fibre and particle panel material.In recent years China's wood veneer output constantly increases, and has accounted for about 40% of wood-based plate ultimate production.Along with scientific-technical progress, the series product of deriving of wood veneer, the continuous appearance of deep processing kind and perfect, all kinds of wood veneers will be applied in the national economy every field more and more widely.
Plywood production be unable to do without tackiness agent, and urea-formaldehyde resin adhesive accounts for more than 80% of wood veneer glue consumption, is the maximum kind of consumption in the tackiness agent.Urea-formaldehyde resin has the incomparable advantage of other resin; Mainly be that its raw material is sufficient, cheap; Be that cost is minimum in the synthetic resins, and transparency height, glue-line do not have color behind the resin solidification, can not pollute by the plate face of cementing thing; Good water solubility is prone to be modulated to needed appropriate viscosity and concentration.But urea-formaldehyde resin also has some significant disadvantages, poor except stability to aging, hot water resistance is poor, can not be as outdoor wood-based plate with the glue, its fatal shortcoming is that cementitious wood-based panel product exists formaldehyde to discharge problem.
The raising day by day of Along with people's quality of life, health perception, artificial board formaldehyde discharge " room air pollution " brought and more and more receive people's attention.Country carries out the production licence management since 2000 to the Wood-based Panel Production enterprise that uses urea-formaldehyde resin to glued joint; Formulated the limitation standard of artificial board formaldehyde burst size-" indoor decorating material wood-based plate and goods formaldehyde thereof discharge and limits the quantity of " (GB18580-2001) December calendar year 2001; This standard was from compulsory execution on July 1 in 2002; According to the requirement of this standard to health environment-friendly, the burst size of methanal of the artificial board that urea-formaldehyde resin glueds joint during as indoor use will reach E
1Grade standard.On January 1st, 2009 rose; California, USA comes into effect about import furniture formaldehyde release new standard; The enforcement of this scheme requires all will reach the F**** level from the burst size of methanal of selection, artificial board substrate's processing, each parts of furniture, and this behave will bring once new innovation to the furniture industry of China.From the furniture base material with just requiring us to research and develop the virgin rubber kind that reaches the California, USA standard-required on the glue.Therefore, the environmental protection urea-formaldehyde glue of exploitation low burst size of methanal has become the outlet that the comprehensive utilization of world today's development timber is generally acknowledged.
The formaldehyde of wood-based plate discharges, and mainly comes from urea-formaldehyde resin.Usually, reducing burst size of methanal must start with aspects such as improving the resin microtexture from reducing the glue free formaldehyde content.Improve the synthesis technique of urea-formaldehyde resin, reduce mol ratio, adding properties-correcting agent and formaldehyde-trapping agent etc. is the method for using always.But the reduction of mol ratio will cause the urea-formaldehyde resin cross-linking density to descend, and tack reduces, and prolong set time, and shorten storage period, and the mechanical property variation of wood-based plate is difficult to satisfy request for utilization; The price of properties-correcting agent and formaldehyde-trapping agent generally all compares expensive, and can make increases the Wood-based Panel Production cost.Therefore, in order to produce the environmental protection urea-formaldehyde resin of low burst size of methanal, not influencing other performance of resin simultaneously again, improve the synthesis technique of urea-formaldehyde resin, is a kind of both economical feasible method.
At present, the synthetic of urea-formaldehyde resin generally adopted traditional " alkali-acid-alkali " technology, promptly at first adds formaldehyde and urea, transfers pH in weakly alkaline, reacts for some time at a certain temperature.Transfer to slightly acidic then, reaction for some time reaches reaction end, transfers pH in weakly alkaline, cooling discharge.The defective of traditional technology is, unavoidably has a large amount of methylols and ehter bond in the molecular resin, and this also is to cause formaldehyde in the wood-based plate solidification process to discharge and the internal cause of poor water resistance.
Application number is that 200910082766.8 patent discloses a kind of low toxic and environment-friendly urea-formaldehyde resin and preparation method thereof, though prepared urea-formaldehyde resin adopts traditional technology, has reasonably controlled the molecular structure of resin, makes it reach the effect of low toxicity.But this urea-formaldehyde resin is only applicable to the veneer compacting wood veneer of normal moisture content scope, and when with high-moisture percentage veneer compacting wood veneer, its precompressed effect and bonding strength obviously descend, and burst size of methanal also increases thereupon.Therefore, set about from synthesis technique, the molecular structure that improves urea-formaldehyde resin becomes the key of head it off.
Summary of the invention
The objective of the invention is provides a kind of " acid-alkali-acid-alkali " technology synthetic low toxic and environment-friendly urea-formaldehyde resin and preparation method thereof to the problem that exists in the above production reality.The urea-formaldehyde resin that the present invention is prepared has reasonably been controlled the methylol group content in the resin, has increased stable cyclic group, has reduced the methylene ether linkage content, has improved the microtexture of resin.The content of free aldehyde of resin is low, and cross-linking density is high during curing, also can reach precompressed effect preferably during for high-moisture percentage veneer compacting wood veneer, and bonding strength is high, and burst size of methanal is low.
For realizing the object of the invention, low toxic and environment-friendly urea-formaldehyde resin of the present invention is processed by following steps:
1) with behind the formaldehyde solution of measuring, the polyvinyl alcohol water solution adding reaction kettle, is heated to the solution clarification;
2) transfer pH to 3-5, preferred 3.5-4.5 adds first urea, and the mole number that makes the formaldehyde that adds in the step 1) is 2.0-3.0 with the ratio of the mole number of first urea: 1;
3) be warmed up to 75-85 ℃, add the trimeric cyanamide and the proper ammonia that account for first urea gross weight 5-15%, transfer pH to 8-10, preferred 8.5-9.5 slowly is warming up to 85-95 ℃, is incubated 30-50 minute;
4) transfer pH to 4-6, preferred 4.5-5.5 reacted 80-100 minute;
5) transfer pH to 5-6, preferred 5.2-5.6 adds second batch of urea, and the mole number that makes the formaldehyde that adds in the step 1) is 1.5-1.9 with the ratio of the total mole number of two batches of urea: 1, react to viscosity 200-300mPas (30 ℃);
6) transfer pH to 7.0-7.5, add the 3rd batch of urea, the mole number that makes the formaldehyde that adds in the step 1) is 0.8-1.4 with the ratio of the total mole number of three batches of urea: 1, begin cooling;
7) be cooled to 65-75 ℃, add the trimeric cyanamide that accounts for the 3rd crowd of urea gross weight 3-8%, be incubated 10-20 minute;
8) be cooled to about 40 ℃, transfer pH to 7.5-8.5 discharging.
Wherein, the weight percent of contained formaldehyde is 36.5-37.4% in the said formaldehyde solution.
Wherein, said polyvinyl alcohol solution should dispose before using in advance, and configuration concentration is 5-10%, and add-on is the 4-8% of formaldehyde gross weight.
Wherein, said polyvinyl alcohol solution should fully stir after adding, and temperature is controlled at 40-60 ℃.
Wherein, the employed acid of accent pH is selected from one or more in concentrated hydrochloric acid, the vitriol oil, formic acid, nitric acid, the acetate.
Wherein, the employed alkali of accent pH is selected from one or more in Pottasium Hydroxide, sodium hydroxide, bicarbonate of ammonia, the methylamine.
In the preferred embodiment of the present invention, said step 2) in, the mole number of the formaldehyde that adds in the step 1) is 2.4: 1 with the ratio of the total mole number of first urea, temperature is 50 ℃.
In the said step 3), the ammoniacal liquor add-on accounts for the 8-15% of weight of urea for the first time.
Under the said step 4) condition, reacted 80-100 minute, reaction solution viscosity should be controlled 100-200mPas (30 ℃).
In the said step 5), the mole number of the formaldehyde that adds in the step 1) is 1.8: 1 with the ratio of the total mole number of two batches of urea, and temperature is 90 ℃.
In the said step 6), the mole number of the formaldehyde that adds in the step 1) is 1.2: 1 with the ratio of the total mole number of three batches of urea, and temperature is 85 ℃.
The present invention adopts " acid-alkali-acid-alkali " synthetic urea-formaldehyde resin; Make and introduce outstanding army (Uron) ring in the molecular resin; After simultaneously ammoniacal liquor adds, and form complicated triazine ring series ring texture between urea, formaldehyde and the performed polymer thereof, reduced the quantity of methylol and ehter bond in the resin.Urea progressively adds the abundant reaction that helps formaldehyde and urea stage by stage, can reduce the content of free formaldehyde in the resin.The adding of Z 150PH has improved the precompressed performance of urea-formaldehyde resin.The effect of trimeric cyanamide is force of cohesion and the water tolerance that improves resin, and reduces free formaldehyde content.
The advantage of the inventive method is: through changing synthesis technique, make the stable ring texture of introducing in the resinous molecular structure, reduced the quantity of methylol and ehter bond.The resin polycondensation is more abundant, good water solubility, and cross-linking density improves during curing, and the bonding strength of compacting high-moisture percentage veneer plywood is high, and burst size of methanal is low.
Embodiment
Describe the present invention in detail through embodiment below, it should be understood that these embodiment only are used for the purpose of illustration, never limit protection scope of the present invention.It will be understood by those skilled in the art that not departing from spirit of the present invention and can make amendment or replace the details of technical scheme of the present invention and form down, but these modifications or replace all fall in protection scope of the present invention with peripheral.
[embodiment one]
The composition of raw materials of table 1 embodiment one
Annotate: the formaldehyde solution that F and U represent respectively to add and the weight number of urea, U
1-U
3Represent the weight number of the urea of first to the 3rd batch of adding respectively, f and u represent the mole number of formaldehyde and urea, u respectively
1-u
3The mole number of representing the urea of first to the 3rd batch of adding respectively, f/u are represented the mole number of formaldehyde and the ratio of the mole number of urea.
Concrete reactions step is following:
1) 37% formalin, PVA solution are added in the reaction kettle successively, open steam heating to 40-50 ℃, steam off;
2) transfer pH=4.0 with formic acid, and slowly add U
1,
Steam off when 3) opening steam valve then and be warmed up to 60-80 ℃ makes it be warming up to 90 ℃ by reaction from heat release, in the time of 85 ℃, adds M
1And ammoniacal liquor, adjustment pH=8.5, insulation is 40 minutes during to 90 ℃;
4) transfer pH to 5.2 with formic acid, reacted 90 minutes, to viscosity 150-180mpas (30 ℃);
5) transfer pH to 5.5 with sodium hydroxide, add U
2, react to viscosity 240-270mpas (30 ℃) under 90 ℃;
6) transfer pH to 7.2 with sodium hydroxide, be cooled to 85 ℃ and add U
3
7) be cooled to 75 ℃ and add M
2, be incubated 20 minutes;
8) be cooled to 40 ℃ with downward modulation pH=8.0 discharging.
The quality index of gained resin:
Solids content: 51.5%
PH value: 8.0
Viscosity (20 ℃): 280mPas
Curing speed: 100s
Free formaldehyde content: 0.09%
Storage period:＞30 days
[embodiment two]
The composition of raw materials of table 2 embodiment two:
Annotate: the formaldehyde solution that F and U represent respectively to add and the weight number of urea, U
1-U
3Represent the weight number of the urea of first to the 3rd batch of adding respectively, f and u represent the mole number of formaldehyde and urea, u respectively
1-u
3The mole number of representing the urea of first to the 3rd batch of adding respectively, f/u are represented the mole number of formaldehyde and the ratio of the mole number of urea.
Concrete reactions step is following:
1) 37% formalin, PVA solution are added in the reaction kettle successively, open steam heating to 40-50 ℃, steam off;
2) transfer pH=4.2 with formic acid, and slowly add U
1,
Steam off when 3) opening steam valve then and be warmed up to 60-80 ℃ lets it from being warming up to 90 ℃, at 85 ℃, the time add M
1And ammoniacal liquor, adjustment pH=8.5, insulation is 40 minutes during to 90 ℃;
4) transfer pH to 5.1 with formic acid, reacted 90 minutes, to viscosity 180-200mPas (30 ℃);
5) transfer pH to 5.5 with sodium hydroxide, add U
2, react to viscosity 240-270mPas (30 ℃) under 90 ℃;
6) transfer pH to 7.2 with sodium hydroxide, be cooled to 85 ℃ and add U
3
7) be cooled to 75 ℃ and add M
2, be incubated 20 minutes;
8) be cooled to 40 ℃ with downward modulation pH=8.0 discharging.
The quality index of gained resin:
Solids content: 52.3%
PH value: 8.0
Viscosity (20 ℃): 260mPas
Curing speed: 120s
Free formaldehyde content: 0.06%
Storage period:＞30 days
[comparative example one]
The composition of raw materials of table 3 comparative example one
Annotate: the formaldehyde solution that F and U represent respectively to add and the weight number of urea, U
1-U
3Represent the weight number of the urea of first to the 3rd batch of adding respectively, f and u represent the mole number of formaldehyde and urea, u respectively
1-u
3The mole number of representing the urea of first to the 3rd batch of adding respectively, f/u are represented the mole number of formaldehyde and the ratio of the mole number of urea.
Concrete reactions step is following:
1) 37% industrial formol is added reaction kettle, transfer pH=8.8-9.0, add U with sodium hydroxide
1, be warming up to 95 ℃ with 30-40 minute, be incubated 60 minutes;
2) transfer pH=4.2-4.8 with formic acid, add trimeric cyanamide, react to viscosity: 120-150mPas (30 ℃);
3) transfer pH to 6.0-6.5 with sodium hydroxide, add U
2, react to viscosity: 180-200mPas (30 ℃);
4) transfer pH=7.0-7.5 with sodium hydroxide, be cooled to 70 ℃, add U
3, insulation reaction 20 minutes;
5) be cooled to 40 ℃ with bottom discharge.
The resin quality index:
Solids content: 50-54%
PH value: 7.5-9.0
Viscosity (20 ℃): 150-200mPas
Curing speed: 90-120s
Free formaldehyde content: 0.2%
Storage period:＞30 days
[comparative example two]
The composition of raw materials of table 4 comparative example two
Annotate: the formaldehyde solution that F and U represent respectively to add and the weight number of urea, U
1-U
5Represent the weight number of the urea of first to the 5th batch of adding respectively, f and u represent the mole number of formaldehyde and urea, u respectively
1-u
5The mole number of representing the urea of first to the 5th batch of adding respectively, f/u are represented the mole number of formaldehyde and the ratio of the mole number of urea.
Concrete reactions step is following:
1) 37% formaldehyde solution is once added in the reaction kettle, open steam heating to 30-40 ℃, steam off;
2) transfer pH=8.8 with sodium hydroxide, add U
1, steam off when opening steam valve then and being warmed up to 60-70 ℃ lets it from being warming up to 90 ℃, insulation reaction 60 minutes;
3) transfer pH to 6.5 with sodium hydroxide, add U
2, reacted 40 minutes;
4) transfer pH to 5.8 with formic acid, add U
3, add trimeric cyanamide simultaneously, 90 ℃ were reacted 20 minutes down;
5) transfer pH to 4.8 with formic acid, react to viscosity: be coated with-4 glasss of 23-25s (30 ℃);
6) transfer pH to 6.0 with sodium hydroxide, add U
4, react to viscosity: be coated with-4 glasss of 30-33s (30 ℃);
7) transfer pH to 7.2 with sodium hydroxide, be cooled to 65 ℃, add U
5, insulation reaction 20 minutes;
8) be cooled to 40 ℃ with downward modulation pH=8.0, discharging.
The quality index of gained resin:
Solids content: 52.7%
PH value: 8.0
Viscosity (20 ℃): 110cp
Curing speed: 109s
Free formaldehyde content: 0.1%
Storage period:＞30 days
[Test Example one]
The low toxic and environment-friendly urea-formaldehyde resin tackiness agent that utilizes the embodiment of the invention one and embodiment two methods to obtain is produced 5 layers of wood veneer test specimen 1,2,3 and 4 respectively with the urea-formaldehyde resin adhesive of comparative example one, the acquisition of comparative example two methods.Wherein, add the flour of weight resin 20% and 0.5% ammonium chloride during gluing; Veneer is 5 years living eucalyptus veneers of production speed, water ratio 12-16%; Heat pressing process is: pressure 1.0-1.2MPa, and temperature is 105-115 ℃, the time is 8 minutes.
According to the II class wood veneer gummed strength test method test block 1,2,3 of regulation among the GB/T 17657-1999 " Test methods of evaluating the properties of woodbased panels and surface decorated woodbased panels " and 4 bonding strength, with the burst size of methanal of 9-11L moisture eliminator method test block 1,2,3 and 4.The result is as shown in table 1:
Table 1
| Project | Test specimen 1 | Test specimen 2 | Test specimen 3 | Test specimen 4 |
| Burst size of methanal, mg/L | 0.67 | 0.42 | 0.79 | 0.68 |
| Bonding strength, MPa | 0.78 | 0.72 | 0.58 | 0.54 |
Visible by table 1, with water ratio 12-16% veneer raw material, the low toxic and environment-friendly urea-formaldehyde glue that utilizes the inventive method to produce is made multiplying plywood.With test specimen 3 (comparative example 1) contrast, the bonding strength of test specimen 1 (embodiment 1) has increased by 34.5%, and burst size of methanal has reduced 15.2%; The bonding strength of test specimen 2 (embodiment 2) has increased by 24.1%, and burst size of methanal has reduced 46.8%.With test specimen 4 (comparative example 2) contrast, the bonding strength of test specimen 1 (embodiment 1) has increased by 44.4%, and burst size of methanal does not almost reduce; The bonding strength of test specimen 2 (embodiment 2) has increased by 33.4%, and burst size of methanal has reduced 38.2%.
[Test Example two]
The low toxic and environment-friendly urea-formaldehyde resin tackiness agent that utilizes the embodiment of the invention one and embodiment two methods to obtain is produced 7 layers of wood veneer test specimen 5,6,7 and 8 respectively with the urea-formaldehyde resin adhesive of comparative example one, the acquisition of comparative example two methods.Wherein, add the flour of weight resin 20% and 0.5% ammonium chloride during gluing; Veneer is 5 years living eucalyptus veneers of production speed, water ratio 8-12%; Heat pressing process is: pressure 1.0-1.2MPa, and temperature is 105-115 ℃, the time is 10 minutes.
According to the II class wood veneer gummed strength test method test block 5,6,7 of regulation among the GB/T 17657-1999 " Test methods of evaluating the properties of woodbased panels and surface decorated woodbased panels " and 8 bonding strength, with the burst size of methanal of 9-11L moisture eliminator method test block 5,6,7 and 8.The result is as shown in table 2:
Table 2
| Project | Test specimen 5 | Test specimen 6 | Test specimen 7 | Test specimen 8 |
| Burst size of methanal, mg/L | 0.52 | 0.39 | 0.68 | 0.46 |
| Bonding strength, MPa | 0.89 | 0.82 | 0.67 | 0.76 |
Visible by table 2, be raw material with water ratio 8-12% veneer, the low toxic and environment-friendly urea-formaldehyde glue that utilizes the inventive method to produce is made multiplying plywood.With test specimen 7 (comparative example 1) contrast, the bonding strength of test specimen 5 (embodiment 1) has increased by 32.8%, and burst size of methanal has reduced 23.5%; The bonding strength of test specimen 6 (embodiment 2) has increased by 22.4%, and burst size of methanal has reduced 42.6%.With test specimen 8 (comparative example 2) contrast, the bonding strength of test specimen 5 (embodiment 1) has increased by 17.1%, and burst size of methanal has reduced 13.1%; The bonding strength of test specimen 6 (embodiment 2) has increased by 7.9%, and burst size of methanal has reduced 15.2%.
Analysis-by-synthesis can know that the low toxic and environment-friendly urea-formaldehyde resin that adopts the inventive method to produce glues together the high-moisture percentage veneer, and when making multiplying plywood, its bonding strength reaches the requirement of GB II class wood veneer, and burst size of methanal can reach E
1And E
0Grade standard.Low toxic and environment-friendly urea-formaldehyde resin producing with the inventive method glues together the normal moisture content veneer, and when making multiplying plywood, its bonding strength is higher, and burst size of methanal is lower.
Claims (10)
1. the preparation method of a low toxic and environment-friendly urea-formaldehyde resin is characterized in that being processed by following steps:
1) with behind the formaldehyde solution of measuring, the polyvinyl alcohol water solution adding reaction kettle, is heated to the solution clarification;
2) transfer pH to 3-5, add first urea, the mole number that makes the formaldehyde that adds in the step 1) is 2.0-3.0:1 with the ratio of the mole number of first urea;
3) be warmed up to 75-85 ℃, add the trimeric cyanamide and the ammoniacal liquor that account for first urea gross weight 5-15%, transfer pH to 8-10, slowly be warming up to 85-95 ℃, be incubated 30-50 minute;
4) transfer pH to 4-6, reacted 80-100 minute;
5) transfer pH to 5-6, adds second batch of urea, the mole number that makes the formaldehyde that adds in the step 1) is 1.5-1.9:1 with the ratio of the total mole number of two batches of urea, and the viscosity number that reacts to 30 ℃ of measuring conditions is 200-300mPas;
6) transfer pH to 7.0-7.5, add the 3rd batch of urea, the mole number that makes the formaldehyde that adds in the step 1) is 0.8-1.4:1 with the ratio of the total mole number of three batches of urea, begins cooling;
7) be cooled to 65-75 ℃, add the trimeric cyanamide that accounts for the 3rd crowd of urea gross weight 3-8%, be incubated 10-20 minute;
8) be cooled to about 40 ℃, transfer pH to 7.5-8.5 discharging;
The weight percent of contained formaldehyde is 36.5-37.4% in the said formaldehyde solution;
Said polyvinyl alcohol solution should dispose before using in advance, and configuration concentration is 5-10%, and add-on is the 4-8% of formaldehyde gross weight;
In the said step 3), the ammoniacal liquor add-on accounts for the 8-15% of weight of urea for the first time.
2. method according to claim 1 is characterized in that, said step 2) the middle pH to 3.5-4.5 that transfers; Transfer pH to 8.5-9.5 in the said step 3); Transfer pH to 4.5-5.5 in the said step 4); Transfer pH to 5.2-5.6 in the said step 5).
3. method according to claim 1 is characterized in that, said polyvinyl alcohol solution should fully stir after adding, and temperature is controlled at 40-60 ℃.
4. method according to claim 1 is characterized in that, the employed acid of accent pH is selected from one or more in concentrated hydrochloric acid, the vitriol oil, formic acid, nitric acid, the acetate.
5. method according to claim 1 is characterized in that, the employed alkali of accent pH is selected from one or more in Pottasium Hydroxide, sodium hydroxide, the methylamine.
6. method according to claim 1 is characterized in that said step 2) in, the mole number of the formaldehyde that adds in the step 1) is 2.4:1 with the ratio of the total mole number of first urea, temperature is 50 ℃.
7. method according to claim 1 is characterized in that under the said step 4) condition, reacts 80-100 minute, and it is 100-200mPas that reaction solution viscosity should be controlled 30 ℃ of viscosity numbers under the measuring condition.
8. method according to claim 1 is characterized in that in the said step 5), and the mole number of the formaldehyde that adds in the step 1) is 1.8:1 with the ratio of the total mole number of two batches of urea, and temperature is 90 ℃.
9. method according to claim 1 is characterized in that in the said step 6), and the mole number of the formaldehyde that adds in the step 1) is 1.2:1 with the ratio of the total mole number of three batches of urea, and temperature is 85 ℃.
10. a low toxic and environment-friendly urea-formaldehyde resin is characterized in that it being to be prepared from according to each described method of claim 1-9.
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| CN102604573A (en) * | 2012-01-12 | 2012-07-25 | 北华大学 | E0-grade melamine modified urea-formaldehyde resin adhesive, and preparation method and application thereof |
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| CN102642223B (en) * | 2012-05-08 | 2014-06-11 | 河北爱美森木材加工有限公司 | Impregnating method of fast growing wood |
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| CN103408712B (en) * | 2013-08-14 | 2015-08-05 | 广西南宁绿园北林木业有限公司 | The production method of low residual formaldehyde polyvinyl alcohol modification urea-formaldehyde resin |
| CN103450431B (en) * | 2013-08-14 | 2016-01-20 | 广西南宁绿园北林木业有限公司 | The production method of low residual formaldehyde urea-formaldehyde resin |
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