CN103450431A - Production method of low-formaldehyde residue urea-formaldehyde resin - Google Patents
Production method of low-formaldehyde residue urea-formaldehyde resin Download PDFInfo
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- CN103450431A CN103450431A CN2013103534434A CN201310353443A CN103450431A CN 103450431 A CN103450431 A CN 103450431A CN 2013103534434 A CN2013103534434 A CN 2013103534434A CN 201310353443 A CN201310353443 A CN 201310353443A CN 103450431 A CN103450431 A CN 103450431A
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Abstract
The invention provides a production method of low-form formaldehyde residue urea-formaldehyde resin. Major raw materials include formaldehyde and urea; formaldehyde is fed once, while urea is fed three times; the production of the urea-formaldehyde resin is divided into three stages of prepolymerization, polymerization and later-period polymerization; the quantity of urea added at each stage is different and the reaction temperatures of the three stages are also different; due to the adoption of the process, a gel phenomenon in the polymerization process is avoided; the obtained urea-formaldehyde resin is narrow in molecular weight distribution, and low in formaldehyde residue; once the urea-formaldehyde resin is used for producing an artificial board, the amount of formaldehyde release of the artificial board can be reduced.
Description
Technical field
The present invention relates to a kind of production method of low residual formaldehyde urea-formaldehyde resin.
Background technology
Wood-based plate is that to take timber or other non-wood plants be raw material, after certain mechanical workout is separated into various unit materials, applies sheet material or pressing that tackiness agent and other additives gummed form.The most frequently used sizing agent of wood-based plate is urea-formaldehyde resin or modified urea-formaldehyde resin.The urea-formaldehyde resin production technique is simple, cost is low, but water tolerance and intensity are lower, the urea-formaldehyde resin after the modifications such as trimeric cyanamide, phenol or Resorcinol, acrylate copolymer, isocyanic ester, polyvinyl alcohol or xylogen obviously improves water tolerance and cohesive strength.One of raw materials for production of urea-formaldehyde resin or modified urea-formaldehyde resin are formaldehyde, therefore, adopt urea-formaldehyde resin or modified urea-formaldehyde resin as the equal inevitable release formaldehyde of the wood-based plate of sizing agent.Formaldehyde is healthy stealthy killer, and indoor concentration of formaldehyde is greater than 0.1mg/m3, and the people stays 5 hours at such environment, will feel dizzy, be in for a long time concentration of formaldehyde and be greater than 0.5mg/m3, will be carcinogenic, so burst size of methanal is an important factor of restriction industry of artificial boards development.
How to reduce the burst size of methanal of wood-based plate? Chinese patent CN201010244439.0 discloses a kind of wood-based plate, this wood-based plate adopts the sizing agent of cyanoethylated fibre as wood-based plate, because the raw material of sizing agent does not contain formaldehyde, avoided the release of formaldehyde, but this sizing agent cost is high, cohesive strength is not very desirable.
Reduce the burst size of formaldehyde, can the residual quantity of monomer formaldehyde realize from reduce sizing agent.Polyreaction has individual phenomenon, is gelatin phenomenon, and reason is that polyreaction is in earlier stage because monomer concentration is high, polyreaction is violent, and the molecular weight of polymkeric substance sharply increases, and polymeric solution viscosity also sharply increases, polymerization single polymerization monomer is difficult to diffusion, the superpolymer be generated wraps, but also polymerization reaction take place of the monomer be wrapped, but because outside polymerization single polymerization monomer is difficult to be diffused into inside, can not carry out make-up monomers to polyreaction, cause the polymerization degree low, the monomer ratio imbalance, cause a kind of monomer residue.The polymkeric substance that the polymerization degree is low easily is subject to the factors such as heat, light and degrades, and discharges monomer.Therefore, the residual quantity of monomer be reduced, the generation of gelatin phenomenon be avoided.
Summary of the invention
The production method that the purpose of this invention is to provide a kind of urea-formaldehyde resin, by reducing the generation of polyreaction gelatin phenomenon, reduce the residual quantity of monomer formaldehyde, produces low residual formaldehyde urea-formaldehyde resin.
Reduce the burst size of formaldehyde, at first will from improving adhesive-preparing technology, by improving adhesive-preparing technology, make raw material formaldehyde almost or complete reaction, reduce the residual quantity of formaldehyde.This adhesive-preparing technology adopts the disposable formaldehyde that adds, and the inferior method that adds urea and trimeric cyanamide, control speed of reaction several times, avoids the generation of gelatin phenomenon, promotes the complete reaction of formaldehyde.Repeatedly add urea, the urea at every turn added and the polymerization rate of formaldehyde and condition are all different, can be divided into prepolymerization, polymerization and polymerization later stage three phases
Prepolymerization: adding formaldehyde solution in reactor, is 2～2.5 with the first acid for adjusting pH value, adds the urea of formaldehyde solution weight 8～12%, is warming up to 50 ℃, insulation reaction 30min.Prepolymerisation stage, because the amount that adds for the first time urea is few, the effective concentration of polymerization single polymerization monomer is low, and the speed of polyreaction is also low, and the simultaneous reactions temperature is low, and polyreaction is gentleer, and the viscosity of reaction solution increases mild, and the molecular weight ratio of polymkeric substance is more even.
Polymerization: prepolymerisation stage finishes, and adds alkali, and the pH value of conditioned reaction liquid is 8～8.5, adds the urea of formaldehyde solution weight 20～25%, adds temperature reaction liquid to 90～95 ℃ then, insulation reaction 90min in 40～60min.Prepolymerisation stage has consumed the part formaldehyde monomers, and the increase of the viscosity of reaction solution, therefore, in order to improve the mobility of reaction solution, needs to improve temperature of reaction, because this stage concentration of formaldehyde has reduced much, therefore can add more urea.
Polymerization later stage: polymerization stage, consumed most of formaldehyde, the concentration of the polymkeric substance that now in reaction solution, the concentration ratio of formaldehyde produces is low, cause the speed of reaction in polymerization later stage very slow, in order to accelerate speed of reaction, can add excessive urea, make the formaldehyde complete reaction, for fear of adding under excessive urea high temperature, with the active group on polymer molecule, react, cause polymericular weight too high, products obtained therefrom viscosity is too high, impact is used, the temperature of reaction in polymerization later stage drops to 70～85 ℃, reaction times 60～90min, the add-on of urea is 40～50% of formaldehyde solution weight, in 40～60min, add, the trimeric cyanamide that can simultaneously add formaldehyde solution weight 2.5%.Unnecessary urea reacts with the active group on polymkeric substance in the hot pressing process of building board production process, increases the molecular weight of polymkeric substance gluing agent, or reacts with the Mierocrystalline cellulose of timber, strengthens the water tolerance of timber.Unnecessary urea also can adopt the method for filtration to remove.
Above-mentioned reaction process always is under agitation carries out.
The polymerization late phase reaction is cooled to room temperature with water coolant to solution after finishing, and obtains low residual formaldehyde urea-formaldehyde resin; Or filter, remove not tolerantly, obtain low residual formaldehyde urea-formaldehyde resin.
Embodiment
Embodiment 1
Prepolymerization: adding formaldehyde solution in reactor, is 2 with the first acid for adjusting pH value, adds the urea of formaldehyde solution weight 8%, is warming up to 50 ℃, insulation reaction 30min;
Polymerization: after prepolymerization finishes, reaction solution adds sodium hydroxide, and conditioned reaction liquid pH is 8, adds the urea of formaldehyde solution weight 20%, adds temperature reaction liquid to 90～95 ℃ then, insulation reaction 90min in 40～60min.
The polymerization later stage: after polyreaction finishes, add the urea of formaldehyde solution weight 50%, add in 40～60min, then temperature of reaction is down to 70 ℃, reaction 90min.Reaction is down to room temperature to reacting liquid temperature after finishing, and filters, and removes unnecessary urea, obtains low residual formaldehyde urea-formaldehyde resin.
Embodiment 2
Prepolymerization: adding formaldehyde solution in reactor, is 2.3 with the first acid for adjusting pH value, adds the polyvinyl alcohol of formaldehyde solution weight 0.5%, is warming up to 50 ℃, insulation reaction 30min;
Polymerization: after prepolymerization finishes, reaction solution adds sodium hydroxide, and conditioned reaction liquid pH is 8.3, adds the urea of formaldehyde solution weight 23%, adds temperature reaction liquid to 90～95 ℃ then, insulation reaction 90min in 40～60min.
The polymerization later stage: after polyreaction finishes, add the urea of formaldehyde solution weight 45%, add in 40～60min, temperature of reaction is down to 80 ℃, reaction 75min.Reaction is down to room temperature to reacting liquid temperature after finishing, and filters, and removes unnecessary urea, obtains low residual formaldehyde urea-formaldehyde resin.
Embodiment 3
Prepolymerization: adding formaldehyde solution in reactor, is 2.5 with the first acid for adjusting pH value, adds the polyvinyl alcohol of formaldehyde solution weight 0.5～0.6%, is warming up to 50 ℃, insulation reaction 30min;
Polymerization: after prepolymerization finishes, reaction solution adds sodium hydroxide, and conditioned reaction liquid pH is 8.5, adds the urea of formaldehyde solution weight 25%, adds temperature reaction liquid to 90～95 ℃ then, insulation reaction 90min in 40～60min.
The polymerization later stage: after polyreaction finishes, add the urea of formaldehyde solution weight 40%, add in 40～60min, temperature of reaction is down to 85 ℃, reaction 60min.Reaction is down to room temperature to reacting liquid temperature after finishing, and obtains low residual formaldehyde urea-formaldehyde resin.
the comparative example 1
Prepolymerization: adding formaldehyde solution in reactor, is 2.3 with the first acid for adjusting pH value, adds the urea of formaldehyde solution weight 5%, is warming up to 50 ℃, insulation reaction 30min;
Polymerization: after prepolymerization finishes, reaction solution adds sodium hydroxide, and conditioned reaction liquid pH is 8.3, adds the urea of formaldehyde solution weight 30%, temperature reaction liquid to 90～95 ℃, insulation reaction 90min.
The polymerization later stage: after polyreaction finishes, add the urea of formaldehyde solution weight 45%, temperature of reaction is down to 85 ℃, reaction times 60min.Reaction is down to room temperature to reacting liquid temperature after finishing, and filters, and removes unnecessary urea, obtains low residual formaldehyde urea-formaldehyde resin.
the comparative example 2
Prepolymerization: adding formaldehyde solution in reactor, is 2～2.5 with the first acid for adjusting pH value, adds the urea of formaldehyde solution weight 15%, is warming up to 50 ℃, insulation reaction 30min;
Polymerization: after prepolymerization finishes, reaction solution adds sodium hydroxide, and conditioned reaction liquid pH is 8～8.5, adds the urea of formaldehyde solution weight 20%, temperature reaction liquid to 90～95 ℃, insulation reaction 90min.
The polymerization later stage: after polyreaction finishes, add the urea of formaldehyde solution weight 40%, temperature of reaction is down to 85 ℃, reaction times 60min.Reaction is down to room temperature to reacting liquid temperature after finishing, and filters, and removes unnecessary urea, obtains low residual formaldehyde urea-formaldehyde resin.
the comparative example 3
Prepolymerization: adding formaldehyde solution in reactor, is 2～2.5 with the first acid for adjusting pH value, adds the urea of formaldehyde solution weight 10%, is warming up to 50 ℃, insulation reaction 30min;
Polymerization: after prepolymerization finishes, reaction solution adds sodium hydroxide, and conditioned reaction liquid pH is 8～8.5, adds the urea of formaldehyde solution weight 30%, temperature reaction liquid to 90～95 ℃, insulation reaction 90min.
The polymerization later stage: after polyreaction finishes, add the urea of formaldehyde solution weight 40%, temperature of reaction is down to 85 ℃, reaction times 60min.Reaction is down to room temperature to reacting liquid temperature after finishing, and filters, and removes unnecessary urea, obtains low residual formaldehyde urea-formaldehyde resin.
According to GB18580-2001 " in indoor decorating and refurnishing materials wood-based plate and goods thereof, burst size of methanal is limited the quantity of ", the sizing agent in embodiment is measured the burst size of formaldehyde, result is as shown in the table:
| Project | Residual formaldehyde/% |
| Embodiment 1 | 0.02 |
| Embodiment 2 | 0.01 |
| Embodiment 3 | 0.02 |
| The comparative example 1 | 0.42 |
| The comparative example 2 | 0.21 |
| The comparative example 3 | 0.46 |
From table, data are found out that the present invention adopts and are added for three times urea, the method in three differential responses stages to produce the glutinous agent of modified urea-formaldehyde resin glue, by rational monomer add-on and polymerization technique, avoided the generation of polyreaction gelatin phenomenon, the products obtained therefrom residual formaldehyde is low, cheap.
Claims (4)
1. the production method of low residual formaldehyde urea-formaldehyde resin, it is characterized in that: its main raw material is formaldehyde and urea, and formaldehyde is disposable feeding intake, and urea divides and feeds intake for three times; The production of urea-formaldehyde resin is divided into prepolymerization, polymerization and later stage polymerization three phases.
2. the production method of low residual formaldehyde urea-formaldehyde resin according to claim 1, it is characterized in that, described prepolymerisation stage: the disposable formaldehyde solution that adds in polymerization reaction kettle, with the first acid for adjusting pH value, be 2～2.5, the urea that adds formaldehyde solution weight 8～12%, be warming up to 50 ℃, insulation reaction 30min.
3. the production method of low residual formaldehyde urea-formaldehyde resin according to claim 1, it is characterized in that, described polymerization stage: prepolymerisation stage finishes, the pH value that adds alkali conditioned reaction liquid is 8～8.5, the urea that adds formaldehyde solution weight 20～25%, add temperature reaction liquid to 90～95 ℃ then, insulation reaction 90min in 40～60min.
4. the production method of low residual formaldehyde urea-formaldehyde resin according to claim 1, it is characterized in that, described polymerization later stage: polymerization stage finishes, the urea that adds formaldehyde solution weight 40～50%, add in 40～60min, then reduce temperature of reaction to 70～85 ℃, react 60～90min, be cooled to room temperature, obtain low residual formaldehyde urea-formaldehyde resin;
Or filter, remove not tolerantly, obtain low residual formaldehyde urea-formaldehyde resin.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103450432A (en) * | 2013-08-14 | 2013-12-18 | 广西南宁绿园北林木业有限公司 | Production method of urea resin with low formaldehyde residual quantity |
| CN105984185A (en) * | 2015-02-03 | 2016-10-05 | 广西南宁绿园北林木业有限公司 | Oriented strand board (OSB) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102086257A (en) * | 2010-06-28 | 2011-06-08 | 永港伟方（北京）科技股份有限公司 | Environment-friendly urea resin for laminating plywoods from high water-content veneers and preparation and application thereof |
| CN103450432A (en) * | 2013-08-14 | 2013-12-18 | 广西南宁绿园北林木业有限公司 | Production method of urea resin with low formaldehyde residual quantity |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102086257A (en) * | 2010-06-28 | 2011-06-08 | 永港伟方（北京）科技股份有限公司 | Environment-friendly urea resin for laminating plywoods from high water-content veneers and preparation and application thereof |
| CN103450432A (en) * | 2013-08-14 | 2013-12-18 | 广西南宁绿园北林木业有限公司 | Production method of urea resin with low formaldehyde residual quantity |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103450432A (en) * | 2013-08-14 | 2013-12-18 | 广西南宁绿园北林木业有限公司 | Production method of urea resin with low formaldehyde residual quantity |
| CN103450432B (en) * | 2013-08-14 | 2016-01-20 | 广西南宁绿园北林木业有限公司 | A kind of production method of low residual formaldehyde urea-formaldehyde resin |
| CN105984185A (en) * | 2015-02-03 | 2016-10-05 | 广西南宁绿园北林木业有限公司 | Oriented strand board (OSB) |
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