CN1803875A - Urea-formaldehyde resin glue produced by making chlorate as catching agent and preparation method thereof - Google Patents
Urea-formaldehyde resin glue produced by making chlorate as catching agent and preparation method thereof Download PDFInfo
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- CN1803875A CN1803875A CN 200510127396 CN200510127396A CN1803875A CN 1803875 A CN1803875 A CN 1803875A CN 200510127396 CN200510127396 CN 200510127396 CN 200510127396 A CN200510127396 A CN 200510127396A CN 1803875 A CN1803875 A CN 1803875A
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Abstract
The disclosed preparation method for urea-formaldehyde glue with solid content as 52-55%, free aldehyde content less than 0.25% and bonding strength more than 1.4MPa comprises: given urea with 100 weight shares, selecting 162-189 formaldehyde, 0.5-2.5 ammonia, 1.0-2.0 melamine, and 2.0-3.0 chlorate as the catching agent for its strong oxidization in acidic medium and stabilization in basic medium; polycondensing; then adding the chlorate. This invention needs low cost, and does not contain overproof formaldehyde both in the product and opposite wood-based panel.
Description
One, the technical field
The invention relates to a urea-formaldehyde resin adhesive, in particular to a urea-formaldehyde resin adhesive produced by taking chlorate as a catching agent and a preparation method thereof.
Second, background Art
The urea-formaldehyde resin adhesive is a polycondensation product of urea and formaldehyde, and is the adhesive with the widest application and the largest use amount in the wood industry. Because the production raw materials are easy to obtain, the production process is simple, the cost is low, the bonding strength is high and the like, the adhesive can not be replaced by other adhesives since being put into production in China in 1957. With the improvement of the living standard of people and the sharp reduction of natural forests, artificial boards are widely applied to home decoration and furniture manufacture, and the problem that the artificial boards release formaldehyde is more and more prominent, which becomes an important factor influencing the home environment at present and seriously threatens the health of people.
Formaldehyde released by the artificial board has two main sources, firstly, due to reversibility and incompleteness of chemical reaction, unreacted raw material formaldehyde is inevitably present in the synthesized urea-formaldehyde resin adhesive; secondly, during the addition reaction, unstable chemical bonds such as hydroxymethyl and methylene are generated, and the unstable chemical bonds are easy to break at high temperature to generate formaldehyde.
In order to solve the problem of formaldehyde release of artificial boards in recent years, technologists developed various urea-formaldehyde resin adhesives with lowfree formaldehyde. Such as low-toxicity urea-formaldehyde resin developed by Zhang dynasty army of Shandong university of Master and Specification, etc. (published in "Chinese Adhesives" 2005, 5 th). The chemical industry of Hunan Tan chemical institute is environment-friendly urea-formaldehyde resin developed by Yangming Heiping (published in No. 1 of 2004 of Chinese Adhesives). Urea-formaldehyde resin with low free aldehyde content of Shufeng (patent No. CN 1621477A). Zhaoying et al, low-aldehyde water-resistant urea-formaldehyde resin (patent application publication No. CN1461786A), Ruiyukun, environmental-friendly urea-formaldehyde resin adhesive (patent application publication No. CN 1262301A).
The invention is characterized in that the invention starts from the urea-formaldehyde glue synthesis process, polyvinyl alcohol, melamine, thiourea and other raw materials which are easy to react with formaldehyde are added, so that the chemical reaction generated during the synthesis of the urea-formaldehyde resin is more complete, and the free formaldehyde content in the glue is reduced. And because more high-price raw materials are added into the urea-formaldehyde resin adhesive, the environment-friendly urea-formaldehyde resin adhesive is high in cost and inconvenient to popularize and use.
Third, the invention
The invention aims to provide a urea-formaldehyde resin adhesive produced by taking chlorate as a catching agent and a preparation method thereof, and provides the urea-formaldehyde resin adhesive with simple production process and low cost for the production of artificial boards; the formaldehyde content in the artificial board produced by using the urea-formaldehyde resin adhesive is reduced.
The technical scheme adopted for realizing the aim of the invention is as follows: in the condensation reaction of urea and formaldehyde, the molar ratio of urea to formaldehyde is adjusted, the dosage of melamine is reduced, the addition time of melamine is adjusted, formaldehyde and urea are fully reacted, and then the reaction is carried out with melamine with relatively sufficient quantity for reducing the free formaldehyde in the urea-formaldehyde resin adhesive, so that the content of the free formaldehyde in the synthesized urea-formaldehyde resin adhesive is as low as possible; the chlorate is added under the alkaline condition after the polycondensation reaction is finished by utilizing the characteristics that the chlorate has stable property in an alkaline medium and shows strong oxidizability in an acidic medium; when the plate is pressed, due to the addition of the amine chloride, an acidic condition is formed, formaldehyde generated by breakage of unstable chemical bonds in the urea-formaldehyde resin adhesive, free formaldehyde and chlorate are subjected to oxidation reaction, and the chemical reaction formula is as follows:
65℃
the raw material feeding ratio for producing the urea-formaldehyde resin adhesive is as follows: based on 100 weight parts of urea, the catalyst is mainly prepared by reacting 162-189 parts of formaldehyde (37 wt%), 0.5-2.5 parts of ammonia water (30 wt%), 1.0-2.0 parts of melamine and 2.0-3.0 parts of chlorate.
The chlorate in the scheme is a formaldehyde catching agent, and specifically comprises the following components: sodium chlorate and potassium chlorate.
The preparation method of the urea-formaldehyde resin adhesive comprises the following steps: the urea is added in portions throughout the reaction. Firstly, 189 parts of formaldehyde solution 162-189 parts are put into a reaction kettle, the PH value is adjusted to 8 by 0.5-2.5 parts of ammonia water and caustic soda solution, the mixture is stirred and heated to 50 ℃, and 62.1 parts of urea is added; and continuously raising the temperature to 90 ℃, keeping the temperature for 30 minutes, adding 6.9 parts of urea, keeping the temperature for 30 minutes, regulating the pH value to be 4-5 by using an acetic acid solution, continuously reacting until the viscosity is 14s (measured by coating 4 cups and measuring 92 ℃), regulating the pH value to be 8 by using a sodium hydroxide solution to terminate the polycondensation reaction, adding 1.0-2.0 parts of melamine and 17.2 parts of urea, introducing cooling water into a jacket of a reaction kettle, adding 13.8 parts of urea and 2.0-3.0 parts of chlorate after 30 minutes, cooling to 40 ℃, and discharging.
The urea-formaldehyde resin adhesive prepared by the scheme has the solid content of 52-55%, the free aldehyde content of less than 0.25% and the bonding strength of more than 1.4Mpa, and meets the national quality standard of the product.
The invention has the following advantages and positive effects:
1. the invention does not use the raw materials of polyvinyl alcohol and thiourea with higher price, correspondingly reduces the dosage of melamine, ensures that the formaldehyde reacts with the urea fully and then reacts with the melamine with relatively sufficient quantity, and has low product cost.
2. Chlorate is introduced as a formaldehyde catching agent, chlorate is added in the prepared urea-formaldehyde resin adhesive under the alkaline condition, when the urea-formaldehyde resin adhesive is used for pressing plates, a curing agent ammonium chloride is added in the urea-formaldehyde resin adhesive, the pH value of the urea-formaldehyde resin adhesive is changed into acidity, formaldehyde and free formaldehyde generated by the breakage of unstable chemical bonds in the urea-formaldehyde resin adhesive are oxidized by the chlorate under the formed acidic condition, the method is very effective for reducing the content of formaldehyde in the artificial plates, and the formaldehyde contained in the produced artificial plates does not exceed the standard.
Fourth, detailed description of the invention
Example 1: preparation of urea-formaldehyde resin adhesive
The raw materials comprise the following components in percentage by weight: 162 parts of formaldehyde (37% wt)940kg, urea (100 parts) 580kg, ammonia water 1.79 parts (30% wt)10.4kg, melamine 1.79 parts 10.4kg, chlorate 2.68 parts 15.5kg, and urea is added in 4 portions in the whole reaction process.
Firstly, 940Kg of formaldehyde solution and 10.4Kg of ammonia water are added into a reaction kettle, sodium hydroxide NaOH (30 percent by weight) solution is added to adjust the pH value to be 8, 360Kg of urea is added when the temperature is raised to 50 ℃ by stirring, the temperature is continuously raised to 90 ℃, 40Kg of urea is added after 30 minutes of heat preservation, the temperature is continuously preserved for 30 minutes, the pH value is adjusted to be 4 by acetic acid (95 percent by weight), the reaction is continuously carried out until the viscosity is 14s (4 cup coating and 92 ℃), the pH value is adjusted to be 8 by sodium hydroxide NaOH (30 percent by weight), and the polycondensation reaction is stopped; adding 10.4Kg of melamine and 100Kg of urea, introducing cooling water into a jacket of a reaction kettle for cooling, adding 15.5Kg of sodium chlorate and 80Kg of urea after 30 minutes, cooling to 40 ℃ and discharging, wherein the detection results of the obtained product are as follows:
viscosity (20 ℃ C.) 120 mPas
pH 8
The solid content is 54.6 percent
The storage period is 30 days
The content of free aldehyde is 0.18 percent
The bonding strength is 1.52 MPa.
When the urea-formaldehyde resin adhesive is used for producing a core-board by a known method, ammonium chloride is added when a board is pressed, the urea-formaldehyde resin adhesive and wood are heated simultaneously, the pH value of the urea-formaldehyde resin adhesive becomes acidic under the action of the ammonium chloride along with the rise of temperature, formaldehyde generated by breakage of unstable chemical bonds in the resin adhesive and free formaldehyde are subjected to oxidation reaction with sodium chlorate to generate carbon dioxide CO2And water H2O, thereby reducing the number of peopleFormaldehyde content in the manufactured board. The produced core-board is detected: the formaldehyde content is 1.41mg/L, which meets the GB18580-2001 national standard.
Example 2: preparation of urea-formaldehyde resin adhesive
The raw materials comprise the following components in percentage by weight: 178 parts of formaldehyde (37 wt%) 2060kg, 100 parts of urea (1160 kg), 2.5 parts of ammonia (30 wt%) 29kg, 1 part of melamine (11.6 kg) and 3 parts of potassium chlorate (35 kg), wherein the urea is added in batches in the whole reaction process.
Adding 2060Kg of formaldehyde and 29Kg of ammonia water into a reaction kettle, regulating the pH value to be 8 by using a sodium hydroxide NaOH (30% wt) solution, heating to 50 ℃, adding 720Kg of urea, continuously heating to 90 ℃, keeping the temperature for 30 minutes, adding 80Kg of urea, continuously keeping the temperature for 30 minutes, regulating the pH value to be 5 by usingacetic acid (95% wt), carrying out polycondensation reaction, regulating the pH value to be 8 by using the sodium hydroxide NaOH (30% wt) solution when the viscosity reaches 14s (measured by coating 4 cups and 92 ℃), stopping the polycondensation reaction, adding 11.6Kg of melamine and 200Kg of urea, introducing cooling water into a jacket of the reaction kettle, adding 35Kg of potassium chlorate and 160Kg of urea after 30 minutes, cooling to 40 ℃, and discharging, wherein the detection result of the obtained product is as follows:
viscosity (20 ℃ C.) 115 mPas
pH 8
The solid content is 54.1 percent
The storage period is 30 days
The content of free aldehyde is 0.22 percent
The bonding strength is 1.68Mpa
The method for producing the board by using the glue is the same as the example 1, and the detection on the core-board produced by using the glue shows that the formaldehyde content is 1.45mg/L, which accords with the GB18580-2001 national standard.
Example 3: preparation of urea-formaldehyde resin adhesive
The raw materials comprise the following components in percentage by weight: 189 parts (37% wt) of formaldehyde 2194kg, 100 parts (1160 kg) of urea, 0.5 part (30%) of ammonia water 5.8kg, 2 parts (23.2 kg) of melamine and 2 parts (23.2 kg) of sodium chlorate, wherein the urea is added in batches in the whole reaction process.
Adding 2194Kg of formaldehyde and 5.8Kg of ammonia water into a reaction kettle, regulating the pH value to be 8 by using a sodium hydroxide NaOH (30% wt) solution, heating to 50 ℃, adding 720Kg of urea, continuously heating to 90 ℃, keeping the temperature, adding 80Kg of urea after 30 minutes, continuously keeping the temperature for 30 minutes, regulating the pH value to be 4 by using acetic acid (95% wt), carrying out polycondensation reaction, regulating the pH value to be 8 by using the sodium hydroxide NaOH (30% wt) solution when the viscosity reaches 14s (measured by coating 4 cups and 92 ℃), stopping the polycondensation reaction, adding 23.2Kg of melamine and 200Kg of urea, introducing cooling water into a jacket of the reaction kettle, adding 23.2Kg of sodium chlorate and 160Kg of urea after 30 minutes, cooling to 40 ℃, and discharging, wherein the detection results of the obtained product are as follows:
viscosity (20 ℃ C.) 123mPa.s
pH 8
The solid content is 52.9 percent
The storage period is 30 days
The content of free aldehyde is 0.23 percent
Adhesive strength 1.71MPa
The method for producing the board by using the urea-formaldehyde resin adhesive is the same as the example 1, and the detection of the core-board produced by using the urea-formaldehyde resin adhesive shows that the formaldehyde content is 1.42mg/L, which accords with the GB18580-2001 national standard.
Example 4: preparation of urea-formaldehyde resin adhesive
The raw materials comprise the following components in percentage by weight: 170 parts of formaldehyde (37 percent by weight) 1972kg, 100 parts of urea 1160kg, 2 parts of ammonia water (30 percent) 23.2kg, 1.9 parts of melamine 22kg and 2 parts of potassium chlorate 23.2kg, wherein the urea is added in batches in the whole reaction process.
1972Kg of formaldehyde and 23.2Kg of ammonia water are added into a reaction kettle, the PH value is adjusted to 8 by using a NaOH (30% wt) solution, the temperature is increased to 50 ℃, 720Kg of urea is added, the temperature is continuously increased to 90 ℃, the temperature is kept for 30 minutes, 80Kg of urea is added, the temperature is continuously kept for 30 minutes, the PH value is adjusted to 5 by using acetic acid (95% wt), the polycondensation reaction is carried out, when the viscosity reaches 14s (measured by coating 4 cups and 92 ℃), the PH value is adjusted to 8 by using NaOH (30% wt) solution, the polycondensation reaction is stopped, 22Kg of melamine and 200Kg of urea are added, cooling water is introduced into a jacket of the reaction kettle, 23.2Kg of potassium chlorate and 160Kg of urea are added after 30 minutes, the mixture is cooled to 40 ℃, and discharged, and the detection result of the obtained product is as follows:
viscosity (20 ℃ C.) 121 mPas
pH 8
The solid content is 53.4 percent
The storage period is 30 days
The content of free aldehyde is 0.22 percent
Adhesive strength 1.61MPa
The method for producing the board by using the urea-formaldehyde resin adhesive is the same as the example 1, and the detection of the core-board produced by using the urea-formaldehyde resin adhesive shows that the formaldehyde content is 1.45mg/L, which accords with the GB18580-2001 national standard.
Claims (4)
1. A urea-formaldehyde resin adhesive produced by taking chlorate as a catching agent is characterized in that: based on 100 parts by weight of urea, the urea-formaldehyde adhesive is mainly prepared by reacting 162-189 parts by weight of formaldehyde (37 wt%), 0.5-2.5 parts by weight of ammonia water (30 wt%), 1.0-2.0 parts by weight of melamine and 2.0-3.0 parts by weight of chlorate, wherein the solid content of the urea-formaldehyde resin adhesive is 52-55%, the free aldehyde content is less than 0.25%, and the bonding strength is more than 1.4 MPa.
2. The method for preparing urea-formaldehyde resin adhesive by using chlorate as catching agent as claimed in claim 1, wherein urea and formaldehyde are condensed to prepare urea-formaldehyde resin adhesive, and the urea is added in batches, and the method is characterized in that: firstly, 189 parts of formaldehyde (37 percent wt) solution of 162-189 parts is put into a reaction kettle, the PH value is adjusted to 8 by 0.5-2.5 parts of ammonia water and caustic soda solution, and 62.1 parts of urea is added when the temperature is raised to 50 ℃ by stirring; continuously raising the temperature to 90 ℃, preserving the heat for 30 minutes, and adding 6.9 parts of urea; keeping the temperature for 30 minutes, adjusting the pH value to 4-5 by using acetic acid solution, continuing the reaction until the viscosity is 14s (measured by coating 4 cups at 92 ℃), adjusting the pH value to 8 by using alkali solution to terminate the polycondensation reaction, adding 1.0-2.0 parts of melamine and 17.2 parts of urea, introducing cooling water into a jacket of a reaction kettle, adding 13.8 parts of urea and 2.0-3.0 parts of chlorate after 30 minutes, cooling to 40 ℃, and discharging.
3. The urea-formaldehyde resin adhesive produced by using chlorate as a capturing agent and the preparation method thereof as claimed in claim 1 or 2, wherein the urea-formaldehyde resin adhesive is prepared by the following steps: the chlorate is a formaldehyde scavenger, and specifically is sodium chlorate or potassium chlorate.
4. The method for preparing urea-formaldehyde resin adhesive by using chlorate as capturing agent as claimed in claim 2, wherein the method comprises the following steps: after the polycondensation reaction is completed, chlorate is added at a pH of 8.
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| Application Number | Priority Date | Filing Date | Title |
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| CNB2005101273967A CN100408607C (en) | 2005-12-25 | 2005-12-25 | Urea-formaldehyde resin glue produced by making chlorate as catching agent and preparation method thereof |
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| CNB2005101273967A CN100408607C (en) | 2005-12-25 | 2005-12-25 | Urea-formaldehyde resin glue produced by making chlorate as catching agent and preparation method thereof |
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| CN1803875A true CN1803875A (en) | 2006-07-19 |
| CN100408607C CN100408607C (en) | 2008-08-06 |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| AU1902601A (en) * | 1999-11-29 | 2001-06-04 | Dynochem Nz Limited | Binders for composite panels |
| CN1111180C (en) * | 2000-05-12 | 2003-06-11 | 中国石油天然气股份有限公司兰州石化分公司 | Water-proof lower-aldehyde urea-formaldehyde resin and its preparing process |
| CN1621477A (en) * | 2004-10-18 | 2005-06-01 | 俞锋 | Urea-formaldehyde glue with low content of free aldehyde and its preparing method |
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