CN1056160C - Modified urea-formaldehyde resin and production process thereof - Google Patents
Modified urea-formaldehyde resin and production process thereof Download PDFInfo
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- CN1056160C CN1056160C CN93112117A CN93112117A CN1056160C CN 1056160 C CN1056160 C CN 1056160C CN 93112117 A CN93112117 A CN 93112117A CN 93112117 A CN93112117 A CN 93112117A CN 1056160 C CN1056160 C CN 1056160C
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Abstract
The present invention relates to a modified urea formaldehyde resin. Urea formaldehyde resin glue is prepared by a way that in a kettle outer circular device, formic acid is used as a catalyst to be condensed in a high formaldehyde molar ratio; hemiacetal polyvinyl alcohol is used as a modifying agent, and persulphate-CMC aldehyde removing regulating agent and sodium silicate are added; condensed resin glue is rapidly decompressed, distillated and dewatered. The modified urea formaldehyde resin has the solid content of more than 58% and the free formaldehyde content in the glue of lower than 0.3%. The primary bonding strength and the bonding strength of a product are high, and a storage period is more than three months.
Description
The present invention is relevant with the binding agent production technology, more specifically says so about producing the improvement technology of modified urea-formaldehyde resin.
Urea-formaldehyde resin is a tackiness agent most widely used in the timber industry, it is the first that output occupy, usually the synthetic urea-formaldehyde glue contains the about 1-3% of free formaldehyde (weight), and initial adhesive strength is low, poor stability, gelation easily takes place in storage and the transportation, so the product of domestic a lot of producers can not be transported for long-distance at present, have only 1-2 month storage period, and use particularly hot pressing plywood of this urea-formaldehyde glue system plywood, there is a large amount of formaldehyde to overflow, seriously contaminate environment.
Patents such as US2467212, special public clear 43-20476, special public clear 48-17877 propose to produce urea-formaldehyde resin with the mol ratio of low formaldehyde, free formaldehyde can reduce to below 1% in the urea-formaldehyde resin adhesive, but the reduction of formaldehyde mole ratio, the stability decreases of urea-formaldehyde resin adhesive, bounding force and initial adhesive strength obviously reduce.
For improving the over-all properties of urea-formaldehyde glue, special public clear 48-1704, patents such as special public clear 55-22519,56-44885, with the polyvinyl alcohol is properties-correcting agent, remove to improve the cohesive strength and the initial adhesive strength of urea-formaldehyde resin adhesive, but cured glue layer poor water resistance, especially the polyvinyl alcohol solvability of high-polymerization degree is bad, easily is separated.
The object of the present invention is to provide a kind of production initial adhesive strength, the bond strength height, free formaldehyde content is low, the urea-formaldehyde resin of good stability improves technology.
The present invention realizes above purpose by a following youngster aspect, free formaldehyde content is closely related in the size of formaldehyde mole ratio and the urea-formaldehyde resin adhesive, reduce formaldehyde mole ratio and can reduce free formaldehyde content, but the reduction of formaldehyde mole ratio makes the stability decreases of urea-formaldehyde resin adhesive.Its bounding force and initial adhesive strength also obviously reduce, therefore solution of the present invention is: at first adopt high formaldehyde mole ratio condensation, the mol ratio of selecting formaldehyde and urea for use is 1.82-1.90, can improve the stability of urea-formaldehyde glue like this and keep initial adhesive strength and bond strength preferably.
In the urea-formaldehyde resin of modification of the present invention, also include the properties-correcting agent polyvinyl alcohol, components such as aldehyde conditioning agent and water-soluble additive disappear, used polyvinyl alcohol is a kind of polyvinyl alcohol of hemiacetalization among the present invention, its molecular weight is 74000-78000, degree of hydrolysis is 88-99%, and its consumption is the 5-10% of reaction-ure mixture, is before urea and formaldehyde carry out condensation reaction, earlier polyvinyl alcohol is added in the formaldehyde, make its abundant hemiacetalization.
So both can impel polyvinyl alcohol fully to dissolve, strengthened the consistency of polyvinyl alcohol, the terminal stage that while is carried out condensation reaction at urea, this part combines with polyvinyl alcohol, and the formaldehyde of the propertyization of being dived, can emit gradually and continue to participate in condensation reaction, the polyvinyl alcohol of some hemiacetalization also can participate in condensation reaction in addition.
The urea-formaldehyde resin that so makes has comprised the urea aldehyde structure of various ways, has improved stability and the bond strength and the initial adhesive strength of urea-formaldehyde resin.Unnecessary formaldehyde then combines with polyvinyl alcohol with the hemiacetal form, and remaines in the urea-formaldehyde resin adhesive, has reduced the free formaldehyde in the urea-formaldehyde resin adhesive system.
An important feature of the present invention is to be added with a kind of aldehyde conditioning agent that disappears.The used aldehyde conditioning agent that disappears is made up of persulphate and Xylo-Mucine, and both ratios are 1: 2.Said Xylo-Mucine is that to select viscosity for use be the Xylo-Mucine of 2500～5000 centipoises.Persulphate wherein can be selected from ammonium persulphate, Potassium Persulphate or Sodium Persulfate, this aldehyde conditioning agent that disappears.Its consumption is the 0.5-2% (weight) of reaction-ure mixture.Persulphate is mixed with Xylo-Mucine earlier, outside persulfate molecule, form a coating layer.And after formaldehyde and the abundant condensation reaction of urea, it is added in the Resin adhesive, be present in the system, both free formaldehyde content in the further minimizing system as latent property catalyzer, and the system plywood is when making hot press operation, the formaldehyde that persulphate discharges in can oxidation system.
The formic acid that generates can further resolve into CO again
2And H
2O, thus the plywood made from the present invention, the sort of peculiar smell that existing plywood distributes.
Disappear Xylo-Mucine in the aldehyde conditioning agent has good dispersiveness in resin, good with the polyvinyl alcohol intermiscibility, it can also cooperate with polyvinyl alcohol, play the dispersion buffer action, improved the initial adhesive strength and the bond strength of urea-formaldehyde resin adhesive, and can improve the stability of Resin adhesive.
Used in the present invention water soluble filler, it mainly is water glass, the modulus of water glass is 3.2, its content is the 5-10% (weight) of total amount of feeding intake, and here water glass is a kind of filler, is again a kind of binding agent, with its replacement solid suspension filler in the past, both can improve the solid content of resin, reduce cost, also improve the initial adhesive strength and the stability of glue.
Another important feature of the present invention is to be that formic acid with 36% concentration is catalyzer in the condensation reaction of urea and formaldehyde, and its consumption is 0.8-1.0% (weight).Be with NH in the prior art
4Cl is a catalyzer, adds ammonium ion and formaldehyde and can play following reaction:
Both consumed formaldehyde, produce acid again, with mineral acid is that the catalyzer condensation reaction is too fierce, the urea-formaldehyde resin adhesive poor stability that generates, be easy to solidify, formic acid is a kind of weak acid, its ionization constant is k=2.4 * 104, is that catalyzer had not both had above-mentioned side reaction with formic acid, and hydrogen ion concentration is low, react more steady, and in the final stage of condensation reaction of the present invention, promptly add the 3rd batch of urea after, the PH of reaction system is transferred to neutrality, this moment is as the formic acid of catalyzer, part generates sodium formiate, adds after the aldehyde conditioning agent that disappears so system is equivalent to exist with a kind of buffered soln form, and persulphate and free formaldehyde react the free formaldehyde content in the further reduction system, but the pH value in the system can not change, thereby the stability of product is more much better than currently available products.
By the modified urea-formaldehyde resin that the present invention obtains, have following characteristics:
1, the modified resin that makes of the present invention, can eliminate free formaldehyde the Resin adhesive from several ways, at first remaining formaldehyde major part combines with polyvinyl alcohol with the hemiacetal form in the system, reduced free formaldehyde content in the glue, the persulphate that exists in the Resin adhesive in addition, free formaldehyde can be oxidized to formic acid as ammonium persulphate, and the ammonium ion that generates in the oxidizing reaction can further participate in the formaldehyde effect of eliminating again, so free formaldehyde content is low in the Resin adhesive of the present invention, its content is less than 0.3%.
2, hemiacetal polyvinyl alcohol that exists in the Resin adhesive and Xylo-Mucine and urea-formaldehyde resin have intermiscibility preferably, part hemiacetal polyvinyl alcohol has been participated in the condensation reaction of urea aldehyde directly, most of hemiacetal polyvinyl alcohol and Xylo-Mucine then play dispersion, buffer action in system, stop the intermolecular further condensation of urea-formaldehyde glue, improved the stability of urea-formaldehyde resin.
3, the polyvinyl alcohol of hemiacetalization and carboxymethyl cellulose sodium have also improved the initial adhesive strength and the bond strength of urea-formaldehyde resin adhesive, and the present invention is used to make plywood, does not need cold pressure procedure, and hot-press solidifying is fast, and heat curing temperature is low, and general heat curing temperature is 105-110 ℃.
The production technique of urea-formaldehyde resin adhesive comprises processes such as condensation reaction and vacuum hydro-extraction, and the key of producing the urea-formaldehyde resin gluing method that the present invention proposes is:
(1) in the formaldehyde solution of 37% concentration, drops into polyvinyl alcohol earlier, under the PH7-8 condition, evenly be warmed up to 90 ℃, be incubated to polyethylene and dissolve fully, this moment the polyvinyl alcohol hemiacetalization, generate polyvinyl formal, the part formaldehyde propertyization of diving has strengthened the pure intermiscibility of poly-second combustion.
(2) be catalyzer with formic acid then, segmentation drops into urea, carries out condensation reaction, and total mol ratio of formaldehyde and urea is 1.82-1.90, generally is divided into three phases and drops into urea; Fs is dropped into the 50-60% of urea total amount, regulate PH to 4.8-5.4, and be warmed up to 90 ℃ of insulation reaction, the urea that adds residual content at last, regulate PH to 7.0-8.0,70-80 ℃ of reaction down, this moment most of free formaldehyde with urea condensation, by the part formaldehyde of the latent propertyization of polyvinyl alcohol, begin to discharge, continue and urea condensation the polyvinyl alcohol group of a part of hemiacetalization, also direct and urea condensation forms the urea-formaldehyde resin structure of various ways, and unnecessary formaldehyde then is retained in the polyvinyl alcohol with the property form of diving.
(3) system is cooled to about 80 ℃, regulate PH to neutral, the aldehyde conditioning agent that disappears that adds 0.5-2%, sustained reaction 40-60 minute, add the water soluble filler water glass again, measure viscosity with being coated with one 4 glasss, can determine dehydrating amount according to viscosity number, when needing dehydration, underpressure distillation dehydration under 27930-34580 handkerchief vacuum tightness makes product reach discharging behind the viscosity of regulation and the solid content.
After urea-formaldehyde glue is made, its dehydration operation condition control, stability to product is also very important, dewatering time is oversize, not only the loss of glue is big, and this glue solidifies easily, influence the stability in storage of urea-formaldehyde glue, for this reason, the present invention adopts a kind of still outer circulation condensing works to carry out the underpressure distillation dehydration, this device is to be connected with tilting condenser with a pipe above reactor, the condenser below connects a separating liquid valve, one end of diverting valve outlet, take back reactor by a pipe, constitute an external circulating system, the other end links to each other with vacuum system, makes liquid when the separating liquid valve is distributed, and liquid can be shunted in proportion, the height of said here ligation still and tilting condenser-tube is a 1-1.2 rice, produce urea-formaldehyde resin adhesive with such covering device, can carry out still outer circulation reaction, formaldehyde is fully utilized and urea condensation generation urea-formaldehyde glue in the condensation reaction stage, can use lower vacuum tightness in the water smoking, at vacuum pressure 27930-34580 pool, about 75 ℃ of distillation temperatures can be finished dehydration operation in 30-60 minute, only save energy consumption like this, the loss of minimizing glue and the stability in storage of glue are also relatively good.
The method that product of the present invention is pressed in HG4-1238-79 and the Japanese JISK6801-1987 standard is measured, the modified urea-formaldehyde resin initial adhesive strength that the present invention makes obviously improves, be used for the hot pressing plywood, do not need to do cold pressing treatment, the over-all properties of urea-formaldehyde resin adhesive, significantly better than the currently available products standard, it is than the results are shown in Table 1.
Table 1 the present invention and currently available products performance comparison
| Index name | Unit | The present invention | HG4-1239-79 | JISK6801-1987 |
| Free formaldehyde draws cuts intensity [pine] compression shear strength [birch] bonding strength [normality] [water-fast] storage period | W% MPa MPa MPa MPa days | ＜0.3 4883.418 16329.726 1363.59 1180.143 ＞90 | 3-7 ＞1962 30 | ＜3 ＞9810 ＞177.2 ＞981 60 |
Advantage of the present invention is clearly, the present invention is the catalyzer of condensation reaction with formic acid, with the hemiacetal polyvinyl alcohol, persulphate-CMC disappear aldehyde conditioning agent and water glass modification, the modified urea-formaldehyde resin glue that obtains, the solid content height, free formaldehyde content is less than 0.3%, and its initial adhesive strength and bond strength height are used for the hot pressing plywood, do not need cold pressure procedure, the excellent storage stability of product reaches more than 3 months storage period, and the present invention is for widening the urea-formaldehyde resin purposes, improve the quality of products, a new way with practical value is provided.
The invention will be further described in conjunction with the accompanying drawings more below.
Accompanying drawing 1 is a process flow diagram of the present invention;
Accompanying drawing 2 is production equipment synoptic diagram of the present invention;
Accompanying drawing, in, 1 is polyvinyl alcohol (PVA) hemiacetalization, in the formaldehyde solution of 37% (weight), drop into polyvinyl alcohol, under the PH7-8 condition, be warmed up to 90 ℃, the insulation dissolve polyvinyl alcohol, the formaldehyde solution that contains the hemiacetal polyvinyl alcohol is sent into and is carried out one section condensation reaction in 2, first part is dropped into 50-60% urea, regulates PH to 5.0-6.7 with formic acid, reacts half an hour down at 60-80 ℃, 3 is second section condensation reaction, second part adds 25-30% urea, transfers PH to 4.8-5.4, is warmed up to 90 ℃ of insulation reaction, 4 is the 3rd section condensation reaction, the 3rd part of urea that adds residual content is transferred PH to 7.0-8.0, and under 70-80 ℃, latent property formaldehyde of part and hemiacetal polyvinyl alcohol group participate in combined reaction, 5 for continuing condensation reaction, add disappear aldehyde conditioning agent ammonium persulphate and Xylo-Mucine at neutrallty condition, continue reaction 40-60 minute down in 70-80 ℃, 6 vacuum hydro-extractions are to proper viscosity, 7 add dissolubility filler water glass, and 8 is product.
Accompanying drawing 2 is produced the production equipment figure of modified urea-formaldehyde resin for the present invention.
Wherein: 1 is reactor, and 2 is receiving tank, and 3 is surge tank, and 4 is vacuum pump, and 5 is pipe connecting, and 6 is condenser, and 7 is return tube, and 8 is the separating liquid valve.
Further specify the present invention with several examples more below, be not confined to certainly among these several examples.
Example one:
1, with 392 parts in 37% (weight) formaldehyde, add in the reactor, start agitator, transfer PH to 8, add 10 parts of polyvinyl alcohol, be warmed up to 90 ℃, polyvinyl alcohol is fully dissolved;
2, add 255 parts of urea for the first time, transfer PH to 6 with formic acid, reacted about 40 minutes, temperature rises to 80 ℃ with 60 ℃;
3, add for the second time 106 parts of urea, transfer PH to 4.8,90-80 ℃ of following insulation reaction about 25 minutes with formic acid;
4, add 60 parts of urea for the third time, total mol ratio of formaldehyde and urea is 1.84 accent PH to 7.5, reacts qualified to cloud point mensuration;
5, under neutrallty condition, add 8 parts of aldehyde conditioning agents that disappear, continue reaction 50 minutes;
6, vacuum hydro-extraction;
7, add 7 parts of water glass;
8, be cooled to 30 ℃ of dischargings.
The quality index of Resin adhesive:
Solid content 58% PH 7.5
Viscosity (second) 40 " content of free aldehyde＜0.3%
Draw and cut intensity [pine] 4883MPa bond strength [normality] 1363.6MPa.
Storage period is more than 90 days.
Example two:
[1]-[5] operating process is identical with example one;
[6] add the weighting agent water glass;
[7] vacuum hydro-extraction;
[8] cool to 30 ℃ of dischargings.
Claims (7)
1, a kind of modified urea-formaldehyde resin mainly contains formaldehyde and the urea reaction condensation forms, and in the condenses and obtain containing properties-correcting agent and other additives, it is characterized in that:
1.1, the mol ratio of formaldehyde and urea is 1.82-1.90;
1.2, contain the properties-correcting agent polyvinyl alcohol in the reactant, its consumption is the 5-10% of reaction-ure mixture, said polyvinyl alcohol is a kind of polyvinyl alcohol of hemiacetalization;
1.3, contain a kind of aldehyde conditioning agent that disappears, its consumption is the 0.5-2% of reaction-ure mixture;
1.4, contain a kind of water soluble filler, its content is the 5-10% of total amount of feeding intake, said water soluble filler mainly is that modulus is 3.2 water glass.
2, according to the described modified urea-formaldehyde resin of claim 1, the molecular weight that it is characterized in that said polyvinyl alcohol is 74000-78000, and its degree of hydrolysis is 88-99%.
3, according to the described modified urea-formaldehyde resin of claim 1, it is characterized in that the said aldehyde conditioning agent that disappears is made up of persulphate and Xylo-Mucine, both ratios are 1: 2.
4, according to the described modified urea-formaldehyde resin of claim 3, it is characterized in that said Xylo-Mucine, is that to select kinetic viscosity for use be the Xylo-Mucine of 2500-5000 centipoise.
5,, it is characterized in that said persulphate is selected from ammonium persulphate, Potassium Persulphate or Sodium Persulfate according to the described modified urea-formaldehyde resin of claim 3.
6, according to the production technique of the described modified urea-formaldehyde resin of claim 1, comprise condensation reaction, add water-soluble filler, vacuum hydro-extraction process, it is characterized in that may further comprise the steps:
6.1, in the formaldehyde solution of 37% concentration, drop into earlier polyvinyl alcohol, under the PH7-8 condition, evenly be warmed up to 90 ℃, make the abundant hemiacetalization of polyvinyl alcohol, the part formaldehyde propertyization of diving;
6.2, be catalyzer with formic acid, segmentation drops into urea and carries out condensation reaction;
6.2.1, the formic acid of 36% concentration, consumption is 0.8-1.0% (weight);
6.2.2, first section 50-60% that drops into the urea total amount, temperature of reaction is that 60-80 ℃, PH are 5.0-6.7;
6.2.3, second section 25-30% that drops into the urea total amount, temperature of reaction is 90-80 ℃, PH is 4.8-5.4;
6.2.4, the 3rd section urea that drops into residual content, with the part property formaldehyde condensation of diving, temperature of reaction is 70-80 ℃, PH is 7.0-8.0;
6.3, add the aldehyde conditioning agent that disappears, under neutrallty condition, continue reaction;
6.4, add water-soluble filler;
6.5, underpressure distillation dehydration, vacuum tightness is the 27930-34580 handkerchief;
6.5.1, distillation temperature is 75 ℃;
6.5.2, dewatering time is 30-60 minute.
7, according to the employed production equipment of the described production technique of claim 6, this device comprises a reactor unit and condensing unit, it is characterized in that wherein being equipped with a still outer circulation condensing unit, be connected a separating liquid valve with tilting condenser with a pipe above reactor, an end of diverting valve outlet takes back reactor by pipe, constitute an external circulating system, the other end links to each other with vacuum system, makes liquid when the separating liquid valve is distributed, and liquid can flow in proportion;
7.1, the height of the pipe of ligation still and tilting condenser is 1-1.2 rice.
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| CN93112117A CN1056160C (en) | 1993-08-20 | 1993-08-20 | Modified urea-formaldehyde resin and production process thereof |
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| CN93112117A CN1056160C (en) | 1993-08-20 | 1993-08-20 | Modified urea-formaldehyde resin and production process thereof |
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| CN1086224A CN1086224A (en) | 1994-05-04 |
| CN1056160C true CN1056160C (en) | 2000-09-06 |
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| CN102443369B (en) * | 2011-10-31 | 2013-06-05 | 东莞市山力高分子材料科研有限公司 | Timber adhesive and preparation method thereof |
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| CN103965425A (en) * | 2013-02-02 | 2014-08-06 | 王笑康 | Preparation method for water-glass modified amino resin |
| CN104044193B (en) * | 2014-07-01 | 2016-01-13 | 中国林业科学研究院木材工业研究所 | The preparation method of a kind of resin type silicate Wood modifier and modifier thereof |
| US9217046B1 (en) * | 2014-07-24 | 2015-12-22 | Hexion Inc. | Methods for preparing stable urea formaldehyde polyvinyl alcohol colloids |
| CN105346178B (en) * | 2015-10-28 | 2018-05-01 | 陕西理工学院 | A kind of plant fiber-Lauxite Environment-friendlycomposite composite board and preparation method thereof |
| CN106078947A (en) * | 2016-06-26 | 2016-11-09 | 周荣 | A kind of modified urea-formaldehyde resin glue plywood preparation method |
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| DD124312A1 (en) * | 1976-01-26 | 1977-02-16 | ||
| SU1016311A1 (en) * | 1981-12-28 | 1983-05-07 | Всесоюзный Научно-Исследовательский Институт Теплоизоляционных И Акустических Строительных Материалов И Изделий | Process for producing water-soluble synthetic binder |
| JPS61106616A (en) * | 1984-10-30 | 1986-05-24 | Mitsui Toatsu Chem Inc | Production of crosslinked urea/formaldehyde polymer particle |
| SU1257079A1 (en) * | 1984-07-12 | 1986-09-15 | Всесоюзный Научно-Исследовательский Институт Деревообрабатывающей Промышленности | Composition for wood particle boards |
| JPH03239712A (en) * | 1990-02-16 | 1991-10-25 | Nippon Kasei Kk | Production of urea resin |
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1993
- 1993-08-20 CN CN93112117A patent/CN1056160C/en not_active Expired - Fee Related
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DD124312A1 (en) * | 1976-01-26 | 1977-02-16 | ||
| SU1016311A1 (en) * | 1981-12-28 | 1983-05-07 | Всесоюзный Научно-Исследовательский Институт Теплоизоляционных И Акустических Строительных Материалов И Изделий | Process for producing water-soluble synthetic binder |
| SU1257079A1 (en) * | 1984-07-12 | 1986-09-15 | Всесоюзный Научно-Исследовательский Институт Деревообрабатывающей Промышленности | Composition for wood particle boards |
| JPS61106616A (en) * | 1984-10-30 | 1986-05-24 | Mitsui Toatsu Chem Inc | Production of crosslinked urea/formaldehyde polymer particle |
| JPH03239712A (en) * | 1990-02-16 | 1991-10-25 | Nippon Kasei Kk | Production of urea resin |
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| CN1086224A (en) | 1994-05-04 |
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