CN102675574A

CN102675574A - Copolycondensation resin type formaldehyde catching agent and preparation method thereof

Info

Publication number: CN102675574A
Application number: CN2012101064393A
Authority: CN
Inventors: 杜官本; 雷洪; 邓书端
Original assignee: Southwest Forestry University
Current assignee: Southwest Forestry University
Priority date: 2012-04-12
Filing date: 2012-04-12
Publication date: 2012-09-19
Anticipated expiration: 2032-04-12
Also published as: CN102675574B

Abstract

The invention provides a melamine-urea-formaldehyde copolycondensation resin type formaldehyde catching agent which is made of urea, melamine and formaldehyde by means of copolycondensation reaction, wherein the final molar ratio F/U of the formaldehyde to the urea is 1:2.4-4.0, the formaldehyde is added once, the urea is added twice, the reaction temperature ranges from 85 DEG C to 95 DEG C, and the reaction time is 2-3 hours. The formaldehyde catching agent can be mixed and used with various urea resin adhesives and especially applicable to urea resins prepared with low molar ratio of the formaldehyde to the urea. Strength of main adhesives of urea resins is unaffected within a certain weight addition proportional range. The melamine-urea-formaldehyde copolycondensation resin type formaldehyde catching agent has the advantages of flexibility in use, high comprehensive performances and the like and is applicable to production of various indoor artificial boards.

Description

A kind of condensation copolymerization resin type formaldehyde-trapping agent and preparation method thereof

Technical field

The present invention relates to a kind of wood-based plate with formaldehyde-trapping agent of urea-formaldehyde resin adhesive and preparation method thereof, belong to Wood-based Panel Production technical field in the wood working.

Background technology

Urea-formaldehyde resin is one type of maximum tackiness agent of present wood-based panel industry usage quantity, but the continuous enhancing of Along with people's environmental consciousness and national environmental protection rules is constantly sound, and the formaldehyde release problem of urea-formaldehyde resin also more and more causes people's attention.As one of principal reaction raw material of urea-formaldehyde resin, formaldehyde has material impact to the health of human body, is classified as suspect carcinogen matter by international cancer institute.Because free concentration of formaldehyde is too high in the UF resin, not only the Working environment to wood working pollutes, and it is unfavorable to bring for for a long time human consumer's health.The method that reduces the artificial board burst size of methanal is a lot, and wherein, the mol ratio F/U that reduces reaction raw materials formaldehyde and urea is the most common a kind of method; But under most situation; When burst size of methanal reduced, the also corresponding deterioration of resin property was in order to take into account the requirement of burst size of methanal and bonding property two aspects; By other method that reduces burst size of methanal, mol ratio F/U generally can not reduce to 1:1.4 ~ 1.2.In urea-formaldehyde resin, still there is certain free formaldehyde with this mol ratio preparation, E1 level burst size of methanal requirement during corresponding timber products is difficult to be up to state standards, the burst size of methanal of urea-formaldehyde resin still has bigger reduction space.In addition, through the preparation technology of control urea-formaldehyde resin, also can the PARA FORMALDEHYDE PRILLS(91,95) burst size produce material impact.

Compare with above-mentioned two kinds of methods, in urea-formaldehyde resin, adding formaldehyde-trapping agent then is the method that a kind of operation is more easy, effect is more obvious, industrial application more is prone to the reduction burst size of methanal of popularization.The composition of forming formaldehyde-trapping agent can be a kind of can with the monomeric substance or the solution of formolite reaction; Can be referring to patent such as DE2917159, EP13372, CN1298911, CN1425725 etc.; It also can be the mixture of multiple material; Can wherein contain the material of multiple seizure formaldehyde referring to patent such as CN1062541, CN101100587, CN1799636, CN1104657 etc.But in general, often be used as formaldehyde-trapping agent and mainly contain ammonia or aminoderivative class material, urea, thiocarbamide mixture, sodium sulfite anhy 96, melamine resin, Resorcinol, ammonium lignin sulfonate, Sumstar 190 etc.

See theoretically, every formaldehyde-trapping agent that can all can be used as urea-formaldehyde resin with the material of formolite reaction, therefore, the urea-formaldehyde resin of the active sites of Shang Youneng and formolite reaction itself promptly can be used as formaldehyde-trapping agent and uses.The resin type formaldehyde-trapping agent is the basis with the condensation copolymerization resin; On the one hand; Free urea wherein and low-molecular-weight adduct can effectively be removed the free formaldehyde in the main gel stick; On the other hand, the existence of resin type methylol polycondensation product can reduce the influence of the reduction of urea and formaldehyde mole ratio to main gel stick strength property to a certain extent, thereby realizes the balance between mechanical strength of resin performance and the burst size of methanal.Therefore, the resin type formaldehyde-trapping agent is more excellent than other formaldehyde-trapping agent over-all properties.

In conjunction with literature search, Shang Weijian have directly use through certain polycondensation, the resinification resin of part is the report of the formaldehyde-trapping agent of urea-formaldehyde resin adhesive.

Summary of the invention

Technical problem to be solved by this invention is to provide a kind of resin base formaldehyde-trapping agent urea-formaldehyde resin, that have certain molecular weight and have certain formaldehyde catching ability that is applicable to, through mix the double standards with realization wood adhesive intensity and burst size of methanal of this trapping agent with urea-formaldehyde resin main gel stick.

" alkali-acid-alkali " technology is selected in the preparation of formaldehyde-trapping agent for use among the present invention, and the final mol ratio F/U of formaldehyde and urea is 1:2.41 ~ 4.0, the disposable adding of formaldehyde, and urea adds at twice, 85 ~ 95 ℃ of temperature of reaction, 2 ~ 3 hours reaction times.

Preparing method's step of melamine-urea-methyl aldehyde copolycondensation formaldehyde-trapping agent of the present invention is following:

1. the reaction initial stage once adds the formaldehyde of metering; Adjustment pH value is between 8.0-8.5; Stir adding down urea, trimeric cyanamide and suitable quantity of water for the first time, the mol ratio F/U of control formaldehyde and urea is at 1:2.0-2.4, and the mol ratio F/M of formaldehyde and trimeric cyanamide is between 1:0.05-0.5;

2. be warmed up to 90 ~ 99 ℃ gradually after stirring reaction 10-30 minute, after under 90 ~ 99 ℃ of conditions insulation reaction 30-60 minute, adjust the pH value between 4.5-5.5, insulation reaction 30-120 minute;

3. adjustment pH value is between 8.5-9.5; Controlled temperature adds urea and ten water Sodium Tetraboratees for the second time under 85 ~ 95 ℃ of conditions, and adds suitable quantity of water control solids content; Control final formaldehyde and urea mol ratio F/U between 1:2.41-4.01,15 ~ 45 minutes postcooling blowings of insulation reaction.

In step 1, be the reaction raw materials except that selecting urea, formaldehyde monomers for use, also can select the preshrunk aggressiveness of urea and formaldehyde for use.But the adjusting operating weight concentration of pH value is 20 ~ 30% aqueous sodium hydroxide solution and 10% aqueous formic acid.

The invention has the advantages that:

1) interpolation of resin type formaldehyde-trapping agent has further reduced the mol ratio of urea-formaldehyde resin main gel stick urea and formaldehyde; Free urea that remains in the system and methylol compound with reactive behavior can with the formolite reaction in the main gel stick, effectively reduce the burst size of methanal of final artificial board;

2) because resin base formaldehyde-trapping agent performance is similar with urea-formaldehyde resin main gel stick performance; Its interpolation can not impact urea-formaldehyde resin adhesive preparation and operating procedure, can mix with various different performance urea-formaldehyde resins to use and to influences such as the curing performance of urea-formaldehyde resin adhesive, sizabilities not quite;

3) adding proportion of resin type formaldehyde-trapping agent can be done corresponding adjustment according to the performance requriements of final wood-based panel product, and flexible operation is easy;

4) preparation of resin type formaldehyde-trapping agent need not to increase relevant equipment input, and preparation raw material and method are all similar with urea-formaldehyde resin, and cost increases not obvious.

The present invention has obtained a kind of resin type formaldehyde-trapping agent, and its characteristics are that trapping agent is the basis with the melamine-urea-methyl aldehyde copolycondensation, and free urea, methylol compound and polycondensation product thereof exist simultaneously in the system, and do not have free formaldehyde.It can mix use with urea-formaldehyde resin main gel stick; Obviously reduce the burst size of methanal of tackiness agent; And in certain weight adding proportion scope, can not cause obvious influence to the strength property of urea-formaldehyde resin main gel stick, preferred adding proportion is 10 ~ 20% of total resin added.This formaldehyde-trapping agent is applicable to various urea-formaldehyde resins, especially is applicable to the urea-formaldehyde resin that is prepared by low urea and formaldehyde mole ratio.Their mixed system is applicable to the production of various indoor level wood-based plates.

Embodiment

Embodiment 1: (every part is parts by weight, gram or kilogram)

1) get 102 parts of urea, 302 parts of formalin solutions and 225 parts of water, the use weight concentration is 20% NaOH aqueous solution adjusting pH value to 8.0;

2) be warming up to 90 ° of C, and under this temperature, reacted 45 minutes;

3) the use weight concentration is 10% aqueous formic acid adjusting pH value to 4.5, continues reaction 60 minutes;

4) regulate pH value to 8.0, add 457 parts of urea and ten water Sodium Tetraboratees and 54 parts of water, insulation reaction is after 20 minutes, and cooling is transferred pH to 8.0 ~ 8.5, blowing.

Embodiment 2: (every part is parts by weight, gram or kilogram)

1) get 207 parts of urea formaldehyde performed polymers (wherein the weight percent of each material is respectively formaldehyde: urea: water=54:23:23), 76 parts of urea and 177 parts of water, using weight concentration is that 20% the NaOH aqueous solution is regulated pH value to 8.0;

2) be warming up to 90 ° of C, and under this temperature, reacted 30 minutes;

3) the use weight concentration is 10% aqueous formic acid adjusting pH value to 5.0, continues reaction 60 minutes;

4) regulate pH value to 8.0, add 323 parts of urea and ten water Sodium Tetraboratees, 50 parts of sodium-chlor and 54 parts of water, insulation reaction is after 20 minutes, and cooling is transferred pH to 8.0 ~ 8.5, blowing.

It is 650 ~ 700g/cm that formaldehyde-trapping agent prepared in accordance with the present invention and urea-formaldehyde resin (urea and formaldehyde mole ratio F/U=1) are mixed with density ³Shaving board, the tackiness agent resin added is 10% of an over dry wood shavings weight, hot pressing time is 5 minutes.When the addition of formaldehyde-trapping agent be total resin added 10 ~ 20% the time; The burst size of methanal of shaving board is 0.44 ~ 0.73mg/L; Do not reduce by 20 ~ 50% when adding formaldehyde-trapping agent; And little to the strength property influence of shaving board, the internal bond strength value of shaving board is 0.5 ~ 0.8MPa, satisfies indoor level wood-based plate performance requriements.

Claims

1. melamine-urea-methyl aldehyde copolycondensation resin type formaldehyde-trapping agent preparation method is characterized in that:

A. reacting the initial stage once adds the formaldehyde of metering; Adjustment pH value is between 8.0-8.5; Stir adding down urea, trimeric cyanamide and suitable quantity of water for the first time, the mol ratio F/U of control formaldehyde and urea is at 1:2.0-2.4, and the mol ratio F/M of formaldehyde and trimeric cyanamide is between 1:0.05-0.5;

B. be warmed up to 90 ~ 99 ℃ gradually after stirring reaction 10-30 minute, after under 90 ~ 99 ℃ of conditions insulation reaction 30-60 minute, adjust the pH value between 4.5-5.5, insulation reaction 30-120 minute;

C. adjust the pH value between 8.5-9.5; Controlled temperature adds urea and ten water Sodium Tetraboratees for the second time under 85 ~ 95 ℃ of conditions, and adds suitable quantity of water control solids content; Control final formaldehyde and urea mol ratio F/U between 1:2.41-4.01,15 ~ 45 minutes postcooling blowings of insulation reaction;

Melamine-urea-methyl aldehyde copolycondensation resin type formaldehyde-trapping agent outward appearance is milky white liquid or paste, is made up of free urea, methylol compound, resin initial stage polymkeric substance and water, and wherein free urea content is 5 ~ 40%; Methylol compound content is 10 ~ 50%, and wherein the dihydroxymethyl compounds content accounts for 40 ~ 90% of total amount; Resin initial stage polymer content is 10 ~ 40%, and molecular-weight average is 100 ~ 500, comprises 1-6 structural unit in the molecular chain.