CS247319B1

CS247319B1 - Process for the production of condensates and / or polycondensates of formaldehyde with urea and melamine

Info

Publication number: CS247319B1
Application number: CS959584A
Authority: CS
Inventors: Michal Kellner; Milan Lichvar; Jaroslav Kossuth; Radislav Lipka
Original assignee: Michal Kellner; Milan Lichvar; Jaroslav Kossuth; Radislav Lipka
Priority date: 1984-12-11
Filing date: 1984-12-11
Publication date: 1986-12-18

Abstract

Sposob výroby kondenzátov a/alebo polykondenzátov formaldehydu s močovinou a melamínom so zníženým únikom formaldehydu dvojstupňovou kondezáciou močoviny a melamínu s formaldehydom. Tieto kondenzáty sa používajú ako pojidlo v drevárskom a nábytkárskom priemysle. Výhodou riešenia je, že živica uvolňuje pri aplikácii vo výrobě DTD, resp. nábytku menej ako 10 mg fd/100 g absolútne suchej DTD podlá DIN EN 120/79, čo vyhovuje emisnej triede E-l podl'a citovanej normy pri zachovaní dobrých lepiacich vlastností a nízkom napučaní hotovej DTD. Podstatou riešenia je spoločná kondenzácia uvedených surovin z predk-ondenzátu močovina-melamín-formaldehyd, pričom vstupný mólový poměr močoviny a formaldehydu je 1:1,5 až 1: 2,2 s výhodou 1:1,90 a poměr melamínu k formaldehydu 1: 1,5 až 1: 10 s výhodou 1 : 3. Výsledný mólový poměr močoviny a formaldehydu je 1:1,1 až 1:1,40 s výhodou 1: : 1,18.Method for producing condensates and/or polycondensates of formaldehyde with urea and melamine with reduced formaldehyde release by two-stage condensation of urea and melamine with formaldehyde. These condensates are used as a binder in the woodworking and furniture industry. The advantage of the solution is that the resin releases less than 10 mg fd/100 g of absolutely dry DTD according to DIN EN 120/79 when applied in the production of DTD or furniture, which complies with emission class E-1 according to the cited standard while maintaining good adhesive properties and low swelling of the finished DTD. The essence of the solution is the joint condensation of the above raw materials from the urea-melamine-formaldehyde pre-condensate, with the input molar ratio of urea and formaldehyde being 1:1.5 to 1:2.2, preferably 1:1.90, and the ratio of melamine to formaldehyde being 1:1.5 to 1:10, preferably 1:3. The resulting molar ratio of urea and formaldehyde is 1:1.1 to 1:1.40, preferably 1:1.18.

Description

247319

BACKGROUND OF THE INVENTION The present invention relates to a continuous, pressurized process for the preparation of condensates and / or polycondensates of foalialdehyde with urea and melamine with reduced formaldehyde leakage by a two-stage condensate of urea and melamine with formaldehyde.

In the application of urea-formaldehyde (UF) adhesives in the bonding process and mainly in the further use of agglomerated materials, mainly in the manufacture of furniture and timber structures, condensates are cleaved to form formaldehyde due to the air humidity and the presence of acidic substances. This formaldehyde has undesirable side effects, deteriorates the environment, and limits the use of a broad range of agglomerated materials. The currently used adhesives produced by the continuous process under elevated pressure of AO 20S 094, 209 101, respectively. 226 922 makes it possible to produce particle board (DTD), which is included in the emission class E-2 according to the internationally valid PESYP method (DIN EN 120/1979). The methodology is based on the perforation of specimens of manipulated DTD with toluene in a prescribed device, prescribed in a manner known to the woodworking public. Formaldehyde, after perforation, is determined by T-shirts, res p at low photolorimetric values after prior staining with chromotropic acid. Adhesives produced according to the above-mentioned AO allow from 10 to 30 mg fd / 100 g of absolute dry DTD (class E-2), which continues in the value of the relevant hygienic standard 0.035 mg fd / m3 of air (fd). formaldehyde).

Reducing formaldehyde leakage is a world-wide problem. In the case of the production of agglomerated materials using standard UF adhesives, the release of formaldehyde by the surface treatment is reduced, in particular by veneering or coating of the boards, respectively. stay in the atmosphere of ammonia. However, these modifications do not ensure that the required requirement for incorporation of boards, furniture, etc. of materials into the emission class E1, the formaldehyde flow below 10 mg / 100 g of ab-solely dry DTDs is achieved.

Manufacturing procedures for stage AO 197 514, AO189 229, USP 3,816,376, USP 3,830,782, USP3,842,039, NSR Pat. No. 2,207,921, U.S. Pat. No. 4,696,191, BP 1,576,365 protect the production of binders by reducing formaldehyde leakage, adjusting the production of binder in the customer, or modifying the finished DTD, but do not provide relievability to the emission class E1, or deteriorate the physical-mechanical properties of the DTD.

Similar procedures for the production of adhesive according to AO185 020, or the modification of the adhesive composition, or the addition of additives according to No. AO 195 490, AO225 416, AO 229 417 provide for the production of DTD, respectively. its treatment at the cost of deteriorating the physical-mechanical properties of the produced DTD, or the preparations are not available to the requisite extent on an industrial scale, or their economy is questionable. In practice, when using AO 235 386, it was found that there was a decrease in form aldehyde leakage from the pressed DTD as determined by the FESYP perforation method from 18 to 20 mg fd / 100 g of absolute dry thatch (AO 206 094) to values of 15 to 17 mg fd / 100 g of absolute dry thatch.

SUMMARY OF THE INVENTION The subject of the present invention is a process for the continuous production of urea-amine-formaldehyde resin with reduced formaldehyde leakage by a two-step condensation of urea and melamine at a temperature of 102 to 130 ° C and a pressure of 0.001 to 0.5 MPa in a continuous flow apparatus, the molar ratio of urea and formaldehyde feedstock is 1: 1.5 to 1: 2.2, preferably 1: 1.90, molar ratio melamine: formaldehyde 1: 1.5 to 1: 10, preferably 1: The urea-melamine-formaldehyde pre-condensate is prepared beforehand in a separate mixing apparatus by the addition of the basic components at a temperature of 10 to 60 ° C and a pHv range of 3 to 20% by weight, preferably 10% by weight. 7 to 10, preferably 8.5, so that the aforementioned molar ratio of feedstocks is maintained. Adjusting the pH is accomplished by the addition of an alkali hydroxide. The pre-condensate prepared is sprayed into a pressure reactor where the first stage of condensation of the feedstock takes place.

It is not precluded to prepare both pre-condensates in the stated proportions alone and to mix them just prior to injection of the pressure step of the reaction. In the second, respectively. by the third reaction stage, further condensation is added to the so-called. a modifying urea which is metered in the form of an aqueous solution at a pressure of 2 to 20 KPa and a temperature of 20 to 90 ° C, pH 5 to 9, preferably 8.2. The components are fed continuously to the second stage, whereby the pH is adjusted by the addition of alkaline metal hydroxides in the form of dilute solutions, most often at a concentration of 10%. The amount of urea added is such that the resulting molar ratio of urea to formaldehyde is in the range of 1: 1.1 to 1: 1.40, preferably 1: 1.18. This amount of urea can be divided into two. The melamine content of the mixture is from 0.005 to 20% by weight, preferably 10% by weight.

According to the present invention, a simple technology provides a resin suitable for use in wood and furniture industry, which has reduced formaldehyde leakage and meets the emission class E1 (formaldehyde leakage below 10 mg fd / 100 g DTD).

The wood bonding parameters of the bonded joint do not deteriorate against the downstream AO 206 094, 209 101, and 2626 922 and improve on AO 235 386.

Claims

Example 1 Into a stirred tank equipped with a cooling jacket, 2.15 m 3 of an aqueous solution of formaldehyde is concentrated at 37% by weight with a content of 0.45% by weight of methanol, the pH of which is adjusted by the addition of 5 µl / cm 3 of sodium hydroxide to 8.5 and 1,260 kg of solid melamine are added. After stirring for 30 minutes, 7.18 m @ 3 of an aqueous solution of E-maldehyde of the same concentration as above was added and 3000 kg of urea were added, the pH of the solution was 6 to 6.1. The ready-to-use precondensate is fed at a rate of 7 m 3 / h to the first reaction stage where a condensation reaction takes place at a pressure of 0.3 MP and a temperature of 120 ° C. The product of the first reaction stage with a viscosity of 80mPa. s is continuously withdrawn to a second reaction stage where further condensation takes place by the addition of 1.75 m 3 / h of 50% non-aqueous urea solution and the pH is adjusted by the addition of 10 1/10% sodium hydroxide. This step is carried out at a temperature of 55 ° C and a pressure of 10.5 kPa. A product with a viscosity of 350mPa is taken from the second reaction step. with a free formaldehyde content of 0.4% by weight, a reactivity of 65 s / 100 CC with ammonium chloride (all according to CSN.66 86 29) and cooled to 20-25 ° C. After curing, the product releases 0.15 mg fd / l of the cured adhesive according to the cited CSNa below 8.5 mg fd / 100 g of absolutely dry DTD according to the FESYP perforation method with toluene - DIN EN 120/1979. Wastewater from the factory contains 0.45 percent by weight of methanol and 1.65 percent by weight of formaldehyde. Example

In a similar manner to the apparatus described in Example 1, 13,430 of 1% formalin having a concentration of 37% by weight were added, the pH was adjusted to 4.5 by the addition of 10% of 10% sodium hydroxide and 5,100 kg of solid urea were added. The mixture was sealed with 20 cc of agitation for about 1 hour and then 4,000 liters of formalin was added, the pH adjusted to 8.5, and 2000kiograms of melamine added. Spray 10 m3 / h. The temperature in the first reactor was 110 ° C, and was condensed until 150 mPa. with viscosity mixtures. In a second step, a second portion of urea is added in an amount of 2.5 m3 / h in the form of a 60% solution, a temperature of 60 ° C, a pressure of 11 kPa. The resulting product collected at a refractive index of 1.482 has a dry matter content of 66.1%, a viscosity of 400 mPa. s, free formaldehyde content 0.45%. FESYP 6 mg released. Example

3 In a similar manner to the apparatus described in Example 1, 17,430 137% formalin is metered in, its pH is adjusted to 4.3 by the addition of 18 L of 10% sodium hydroxide and 5,100 kg of solid urea are added. The mixture is stirred for 1 hour at 18-20 ° C, then the pH is checked and if necessary, the sodium hydroxide addition is adjusted to 8.2-8.5a and 1800 kg of solid melamine are added. The mixture was stirred for 10 min. stirring the first reactor at 10 m 3 / h. The next procedure is as in Example 1. The resulting product collected after the refractive index of 1.480 has a dry matter content of 65.7 wt%, a viscosity of 190 mPa. % of formaldehyde is 0.30% by weight. The released fd from the DTD test according to the FESYP method of 8.2 mg / 100 g of absolutely dry DTD. SUBJECT MATERIALS A process for the production of formaldehyde condensates and / or urea with urea by amine amine with reduced formaldehyde leakage by two-stage condensation of urea and melamine with formaldehyde characterized in that the condensate is condensed at 80 to 130 ° C in the first stage. with a temperature of 120 ° C and a pressure of 0.001 to 0.5 MPa in a continuous continuous plant, the basic molar ratio of the feedstock urea and formaldehyde being 1: 1.5 to 1: 2.2, preferably 1: 1.9, the melamine content of the product is preferably 0.005 to 20% by weight, preferably 10% by weight, at pH 4.5 to 8.5, preferably 6.2, which is treated with alkali metal hydroxide, preferably sodium hydroxide, and the mixture is further condensed in a second stage and concentrating at a pressure of 2 to 20 kPa, a temperature of 20 to 90 ° C, preferably 55 ° C to a dry matter content of 50 to 70% by weight with continuous addition of urea so that the final molar ratio of urea to formaldehyde is 1: 1.1 to 1: 1.40, preferably 1: 1.18 with the addition of alkali metal hydroxide, preferably sodium hydroxide at pH 6 to 9.5, preferably 8.5.