CS262629B1 - A method for producing a low-toxicity melemphine adhesive - Google Patents

Abstract

Method for producing a low-toxic adhesive with reduced melamine content, characterized in that by mixing component A prepared by mixed condensation of urea and formaldehyde with melamine and component B prepared with urea, formaldehyde and ammonia compounds, an adhesive suitable for the production of agglomerated material with reduced formaldehyde release, complying with emission class E-1 according to DIN EN 120/79, is prepared. The mutual ratio of both components is 5 to 95 parts of component A to one part of component B.

Description

262629 2

SUMMARY OF THE INVENTION The present invention provides a method for producing a low-toxicity melamine-based adhesive for use in the wood and furniture industry as a binder in the manufacture of agglomerated materials and furniture that satisfy the El emission class PESYP / up to 10 mg formaldehyde / 100 g material. according to DIN EN 120/79 /.

Despite a number of advantageous properties / high reactivity, relative low cost, the availability of raw / urea-formaldehyde adhesives from the environmental point of view have the disadvantage that the hydrolysis at elevated temperature and humidity results in the removal of formaldehyde and its subsequent and long-term release from agglomerated material and articles to tejtobáze.

The increased concentration of formaldehyde (Fd) in the working air in the production of agglomerated DTD materials, plywoods and furniture, in most cases in areas with reduced airflow, in the living space worsens the working conditions. Formaldehyde already irritates the respiratory tract and conjunctiva in low air concentrations by the operators of production equipment, resp. user of agglomerated products and furniture. Products bonded with standard urea-formaldehyde binders produced according to AO 206 094, 226 922, resp. 235,386, satisfying E-2 / up to 30 mg Fd / 100 g material according to DIN EN 120/79 /. Therefore, the worldwide trend in the development of binders for agglomerated materials, especially urea-formaldehyde in the course of their manufacturers, is to reduce the free formaldehyde content of them, prior to their use in the production of agglomerated materials and to produce condensate / adhesives that would guarantee the product in the agglomerated materials, furniture and plywood. emission classE-l.

Reducing formaldehyde is a global problem. Production procedure according to AO 197 514, AO 189 229, USP 3,816,376, USP 3,830,782, USP 3,842,039, NSR Pat. No. 2,207,921, U.S. Pat. No. 496,191, BP 1,376,365 protect the production of a binder with reduced formaldehyde leakage, respectively. they protect the cushioning adjustments just before application to the consumer, but do not ensure reliable E-1 or E-1 emission levels. is the production economy questionable.

Similar procedures for the production of adhesive according to AO 185 020, or the modification of the adhesive composition, or the addition of additives according to AO 195 490, AO 225 416, AO 229 417, ensure the production of agglomerated material at the cost of deteriorating the physico-mechanical properties of the product, or available.

Binder production procedures according to AO 248 596 resp. AO 252 958 guarantees the production of adhesive by the agglomerated materials of emission class E-1.

However, the procedure of AO 248 596 is based on the treatment of the adhesive with deficient melamine. The procedure of AO 252 958 provides a binder which, when applied in practice, provides a deterioration of the water-swellable resistance of the article to be sealed according to ČSN 490 164 (1975), but leakage / emission / formaldehyde of the product is very low 4 to 5 mg Fd / 100 g of product. SUMMARY OF THE INVENTION The present invention relates to a process for the production of a low-toxicity urea-based melamine-based adhesive, melamine-atriomethyl-trimethylenetriamine, and the like. intermediates thereof, characterized in that, as component A, a urea-formaldehyde precondensate containing melamine is used, which is prepared in a separate mixing apparatus by addition of formaldehyde to urea and melamine at a temperature of 10 to 50 ° C and a pH in the range of 3.5 to 10, preferably 8. Wherein the pH of the aqueous formaldehyde solution needs to be preconditioned by the addition of alkali / alkaline earth metals (thereby preventing the formation of ammonium formate from the present formic acid / concomitant formaldehyde impurity) and ammonia (present in free form in the urea) having a buffering capacity and a negative effect of narcotics ability / activity / future product. The molar ratio of urea to formaldehyde is 1: 1.3 to 1: 1.25, preferably 1: 1.95. The molar ratio of melamine to formaldehyde is 1: 1.15 to 1: 1.10, preferably 1: 3.

This addition product is contacted in the reaction apparatus at a temperature of 60 to 130 ° C at a pH of 3.44 to 13, preferably 6.2 to a condensation product having a viscosity of 15 to 300 mPa.s. Originated 3 262629

the condensation product containing about 0.7% by weight of free formaldehyde is adjusted by the addition of urea to a final molar ratio of urea: formaldehyde of 1: 1.1 to 1: 1.25, preferably 1: 1.16 with simultaneous or subsequent evaporation of the product to a dry matter content of 50 to 80% by weight. preferably 65 wt.

Component B - Urea-formaldehyde condensate containing trimethyloltrimethylene triamine and its intermediates is prepared in three stages. in the first step, ammonia is added to the aqueous formaldehyde solution in an amount such that the molar ratio of formaldehyde to ammonium ionubole is greater than 1: 6.1. In view of the desired formation of hexamethylenetetramine intermediates and the desired properties of the addition product, it is preferable to prepare the first stage product at a mole ratio of formaldehyde to ammonium ion of 1.9 to 3.5: 1 at a temperature of 10 to 70 ° C and a pH of 7 to 13. Preferably aqueous ammonia solution may be used.

Separately, by adding urea to the formaldehyde solution at a molar ratio of urea: formaldehyde of 1: 1.3 to 1: 2.5, preferably 1: 1.95 and pH in the range of 3.5 to 10, preferably 9.0 at 10 to 50 ° C. C prepares the addition product, the pH of the aqueous formaldehyde solution is adjusted by the addition of alkali.

Addition-condensation, respectively. the addition products are mixed in a second weight ratio of 4 to 99 parts of the urea-formaldehyde addition and / or addition condensation product to 1 part of the formaldehyde and ammonia addition condensation product and are contacted at 60 to 130 ° C at pH 4 to 13, preferably 5.8 to a condensation product having a viscosity of 15 to 300 mPa.s. The resulting condensation product contains ccahmot. the free formaldehyde additively adds urea to the final molar ratio of urea to formaldehyde of 1: 1.1 to 1: 1.5 in the next / third / so-called modification step, preferably 1: 1.16, with simultaneous or subsequent evaporation of water to dry matter content 50 % to 80 wt. preferably 65 wt. The resulting product consists of component A of component B which is mixed together before or after evaporation in a ratio of 5 to 95 parts of component A: one part of component B.

The present invention provides a resin suitable as a glue for woodworking and furniture industry, which has reduced formaldehyde leakage and meets the E-1 / Fd emission class below 10 mg Fd / 100 g of product. The timber parameters of the glued joint suit. In addition to the above cited, a considerable advantage of the present invention is the reduction of the deficient homlamine content (which results in an improved economy of the binder production process and its application in practice) and an increase in shelf life / product versus AO 248 596. Example 1 o

Component A - 6,400 L of an aqueous solution of formaldehyde having a concentration of 37% by weight, which is cooled to a temperature of about 20 ° C, is added to a stainless steel tank of 10 m with a gearbox stirrer, cooled to about 20 ° C, 10% added. sodium hydroxide solution to pH 4 to 4.5 and 2500 kg of urea are added with stirring.

After stirring for 30 minutes, 375 kg of melamine are added and, after checking and possibly adjusting the pH, 8 to. 8.5, the addition product is pumped to a condensation apparatus where condensation to the desired condensation step (18-22 ml acetone) takes place at 80-105 ° C.

Adjust the pH with NaOH to 6.5 to 7.5 and modify with a urea solution containing 2,100 liters and 2,100 kg of urea. The apparatus is discharged into the product container after cooling to about 25 ° C.

Component B - In a similar apparatus, an addition-condensation product was prepared with 6,600 L of an aqueous formaldehyde solution, the pH of which, after treatment with NaOH, was 4 to 4.5, and 256 kg of urea were added. In a separate cooling and mixing apparatus, the formaldehyde product with aqueous ammonia solution is dispensed at 325 L of 37% formalin, which is gradually fed with 320 L NH 4 OH (28%) so that the temperature does not exceed 50 ° C.

The ammonia addition product of formaldehyde is mixed with the urea addition product and formaldehyde.

Claims (2)

262629 4 dehydu. The mixed precondensate at pH 7.5 to 13 is pumped into the condensation apparatus, and condensation to the desired condensation degree (16-25 acetone) takes place at a temperature of 80-105 ° C. Adjust the pH with NaOH to 6.5 to 7.5 and modify with urea solution. After cooling to about 30 ° C, the camera is discharged into the intermediate product. Preparation of Semi-Product A resp. B takes the 3 - 2 lead. The semi-product mixture was evaporated in vacuo at 60 ° C to a dry matter content of min. 65 wt. and cooled to 20 ° C. The adhesive produced, after analysis, had a dry matter content of 65.7% by weight. (3 g / 120 ° C / pH 8.5, viscosity 155 mPa.s) reactivity at 100 ° C with ammonium chloride / 15% aqueous solution 1: 10/85 s, melamine content 3.1% wt. The formaldehyde emission from the pressed agglomerated material / wood-chipboard / DIN EN 120/79 was 7.5 mg Fd / 100 g absolute dry DTD. Flexural strength 17.3 MPa, tensile strength perpendicular to plane 0.45 MPa, swelling after 2 h 6.55%. Example 2 In the apparatus described in Example 1, component A and components B were prepared according to an identical method and mixed in a 2: 3 ratio prior to evaporation. After evaporation, the poorly produced glue, after analysis of the dry matter content of 65.9% by weight, pH 8.3, had a viscosity of 170 mPa.s. reactivity with dichloroammonium 731, melamine content 2.1 wt. Fd emissions from DTD 6.8 mg Fd / 100 g DTD. The physical-mechanical properties of the DTD fit! Example 3 Component A and Component B were mixed after evaporation in a 1: 1 ratio. Analysis of the product: Content 65.6% by weight, pH 8.4 viscosity 200 mPa.s. reactivity with NH 4 Cl 80 s, melamine content 2.6 wt. Fd emissions from DTD 7.3 mg Fd / 100 g DTD. Physico-mechanical properties fit:! Example 4 Component A: 6,300 L of an aqueous solution of formaldehyde at a concentration of 36.7% by weight, which is cooled to about 25 ° C, is added to a stainless steel tank of 10 m with a gearbox stirrer, which is cooled to about 25 ° C. % sodium hydroxide solution so that the pH is between 3.9 and 4.2 and 2,600 kg of urea are added with stirring. After 25 min. 425 kg of melamine are added by stirring and, after adjusting the pH to 9.3-9.5, the addition product is pumped into a condensation apparatus where the condensation step (16-20 ml acetone) is condensed to the desired condensation step at 90-102 ° C. Adjust the pH with NaOH to a value of 6.8 to 8.2 and modify with a urea-containing solution of 2050 L of water and 2,000 L of urea. The apparatus was drained and evaporated in vacuo at 60-65 ° C after cooling to 30 ° C. Component B prepared according to Example 1 (after evaporation) was mixed in a ratio of 90: 10 wt. parts. Product analysis. Dry matter content 66.01 wt%, pH 8.2 viscosity 210 mPa.s, reactivity and NH 4 Cl at 100 ° C 150 s, melamine content 3.9 9 wt. Fd and DTD emissions 8.1 mg Fd / 100 gDTD, flexural strength DTD 17.6 MPa, tensile strength perpendicular to the 0.50 MPa plane, swelling 2 4 7.1%. durability 30 days / 20 ° C. SUBJECT MATTER A process for producing a low-toxicity melamine-reduced adhesive characterized in that, as component A, a precondensate is prepared by co-condensation of urea and melamine with formaldehyde at 1: 1.3 to 1: 2.5, preferably 1: 1.95 and a molar ratio of melamine: formaldehyde of 1: 1.15 to 1:10 preferably 1: 3 at pH 3.4 to 13, preferably 6.2, which is adjusted by the addition of hydroxides, or alkali earth carbonates or metals, preferably sodium hydroxide. the precondensate is brought together at a temperature of 80 to 130 ° C to the desired condensation degree, expressed in a dynamic viscosity, which is in the range of 15 to 300 mPa · s / 20 ° C, preferably 30 to 70 mPa · s / 20 ° C. alkali metal, or ammonia preferably sodium 5,262,229 to values of 6.5-8.6, further condensed by the additional addition of modifying urea by continuous and / or discontinuous treatment such that the resulting molar ratio of urea and formaldehyde is 1: 1.1 to 1: 1.25, preferably 1: 1.16, the melamine content of component A ranges from 0.5 to 20% by weight. preferably 5% by weight, as a component B, a three-stage urea-formaldehyde condensate is prepared, wherein in the first stage the addition / / addition-condensation products of formaldehyde and ammonia, or an aqueous solution thereof, are prepared in such a way that the molar ratio of formaldehyde to ammonium ion was higher than 1.6: 1, preferably from 1.9 to 2.5: 1 at 10 to 70 ° C and pH 7 to 13, and from formaldehyde and urea at an inlet ratio of 1: 1.13 to 1: 2.5, preferably 1: 1.95 at a temperature of 10 to 50 ° C, pH in the range of 3.5 to 10, preferably 8.0 in the second stage, separately prepared products are contacted together at 105 ° C, in a weight ratio of 1 to 99 parts by weight of urea-formaldehyde product for one part of the reaction product of formaldehyde with ammonia to a condensation degree expressed by a dynamic viscosity ranging from 15 to 300 mPa · s / 20 ° C, preferably 30 to 70 mPa · s / 20 ° C, in the third stage the resulting condensation product was modified The resulting product consists of component A and component B, which are mixed together at a ratio of 5 to 95 parts of component A: to one to one. part of component B and evaporate to a dry weight of 50 to 80% by weight. preferably 65 wt. 2. A method as claimed in claim 1, wherein components A and B are mixed after evaporation at a pressure of 2 to 150 KPa at a temperature of 40 to 90 ° C, after cooling to 15 to 60 ° C in a ratio of 5 to 95 parts of component A: % to one part of component B, to dry matter 50 to 80% by weight, preferably 65% by weight;