CS210562B1 - Process for producing aminoformaldehyde condensates and / or polycondensates with controlled viscosity - Google Patents

Abstract

The invention solves the problem of preparing aminoformaldehyde condensates and/or polycondensates with a minimized amount of free and released formaldehyde with simultaneous adjustment of viscosity by adding high molecular weight polycondensates, especially polysaccharides. The invention can be used* either in the production of urea-formaldehyde and/or melamine-formaldehyde condensates or in processors, especially in the wood industry, e.g. in the production of wood fiber or chipboard materials.

Description

SUMMARY OF THE INVENTION The present invention provides a problem of the preparation of eminoformaldehyde condensates and / or polycondensates with a minimized amount of free and released formaldehyde with simultaneous adjustment of viscosity in addition to high molecular weight polycondensates, in particular polysaccharides.

The invention can be used either in the production of urea-formaldehyde and / or melamine-formaldehyde condensates or in spraoovatols, especially in the woodworking industry, for example in the manufacture of fibreboard or wood-chip materials. 210 562 1 210 5βί

The invention relates to the production of viscosity-controlled condensates and / or polycondensates even at reduced formaldehyde-free, mainly urea-formaldehyde and / or melamine-formaldehyde compounds, such as resins, binders and adhesives, especially in the woodworking industry and in the manufacture of solid materials. in the construction, technically unpretentious, suitable especially from the technological point of view. . In the production of urea-formaldehyde and melamine-formaldehyde condensates, the finished products contain various amounts of free and released formaldehyde, which is hygienically harmful and which is released not only when these condensates are applied, e.g. papierspraoujúoomom industry, but also escapes from the finished product (boards, furniture, or even log buildings made of the material), does not boggle, which ultimately significantly reduces the quality and utility value of the final products.

When looking for a suitable method to reduce the formaldehyde exhalations from its condensates, respectively. polycondensates that have found a simple and reproducible method of reducing the free formaldehyde content of viao as the formaldehyde and the released formaldehyde by as much as ten times (CSA 195 006, 195 490).

However, this method, which is otherwise technologically and economically suitable, has the disadvantage of reducing the viscosity of the final product. However, lowering the viscosity requires an increased consumption of glue by the crawler or modification of condensation conditions in the manufacturing. Extending the reaction time, possibly increasing the condensation temperature, increases the condensate viscosity, but has more negative side effects. It requires a substantial increase in control and technological vigilance, since especially in discontinuous manufacturing efforts to achieve the desired viscosity, raw materials and condensates can be reacted to the point that the batch is depreciated or lost. it is essential to shorten the life of the condensate, possibly the polycondensate.

The above-mentioned disadvantages are eliminated by the method according to the invention, according to which the process for the preparation of aminoformaldehyde condensates and / or viscosities polycondensates, in particular based on urea formaldehyde via a molar ratio of formaldehyde to urea of 1.01 to 1.29, is carried out in such a way that the viscosity is controlled by additions 0.1 to 10%, preferably 1 to 3% by weight, of water-soluble or swellable cellulose derivatives and / or starch, calculated on the weight of the final product. An advantage of the present invention is the fact that without changing the condensation mode, it is possible by simple mixing of high molecular weight substances, in particular polysaoharides, into the final urea formaldehyde condensate, respectively. of the polycondensate, l'not to change the viscosity to the desired value without affecting any other physical properties. Additions already in a minor amount substantially affect the viscosity of the product so that they do not substantially affect the cost of the product, do not prolong the reaction time. Thus, they do not reduce the plant's performance, but, on the contrary, it has the necessary amount of live polycondensates in application, particularly in the form of glues of fiberboard or chipboard. At the same time, the viscosity of condensates 210 502 and / or polycondensates at reduced free and released foxmaldehyde content and can be adjusted by simple mixing of urea-formaldehyde, respectively. melamine-formaldehyde condensate β polysaoharide, without reducing the reactivity of the final product.

Addition of polyeaoharide, roep. its at least half-water-soluble polysaoharide derivatives, and can be applied in the inhibiting time of condensate and / or polycondensate preparation. It can also be used directly in the preparation process, ie either by dosing either together with the raw materials and / or separately into the reaction stage S1 of the prooes node, more preferably, and applying the polysabharide only after concentrating the formaldehyde condensate to the desired degree, directly at the temperature. thickening, or after partial or complete cooling, for the manufacture of condonates and / or polycondonates, or up to the processor.

As additions to the co-solubilized condonate and tested a number of substances, the best results are achieved and applied by polysaoharide-based agents, and in particular by the use of polysaoharide-based substances, and in particular by the application of polysaoharide-based substances. based on cellulose, in particular water soluble derivatives of oolulose, such as oellulose ethers (methoxy cellulose, ethoxy cellulose, hydroxyalkyl cellulose, carboxymethyl cellulose), but also starch, in particular amylases, by smelting. in sticky substances, starch starch, and the like, or in the form of flour, e.g., yeast or rye flour and the like. While it is possible to apply cold-reacted oolulose derivatives, it is preferable to apply starch at a temperature above 50 ° C, eg 70 ° C for an annual period of 1 h. Further increase in temperature, roep. prolonging the reaction time is unsuitable because it shortens the life of formaldehyde condensate. The application of the aforesaid substances is carried out in the form of condensates and / or polycondensates in which the resulting formaldehyde to molasses ratio can be adjusted by various reactants and foxmalde to provide from 1.01 to 1.29 moles of formaldsihyde for reaction with urea . That is, for example, for every 1.5 mole of formaldehyde in the condensate and / or polycondensate, and 0.49 to 0.21 mole of nitrogenous compound such as melamine, hexamethylenediamine, ammonia and the like. and to the bound 1.01 to 1.29 moles of formaldehyde, 1 mol of urea is available, without penetra- tion, the codes are formaldehyde, urea, reap. other and formaldehyde reacts. However, it is preferable to prepare the acacal condensate, respectively. bind the urea polycondensate and / or allobody melamine and formaldehyde to free-form formaldehyde to meet the optimum molar ratio requirement. Other advantages and details of the method of the present invention will be apparent from the examples, not limiting the scope of the invention. options apply. Example 1

MoSwine formaldehyde condensate, or polycondensate prepared with a molar ratio of formaldehyde: urea of 2.0 with a dry matter content of 71%, with a formaldehyde content of 6.43% by weight. is further adjusted to the resulting molar ratio of formaldehyde to urea and 1.20 with an aqueous urea solution. 70 wt. at 50 ° C, stirring for 2 h.

While the finished product after cooling to 20 ° C has a viscosity of 34.6 s, pickled 3 210 56 in a Ford funnel with a 4 mm hole, with a free formaldehyde content of 0.18 wt.%, The released formaldehyde is 0.55 mg / g of cured polycondensate and reactivity at 100 ° C 85 sec. starch affects viscosity as follows (Table 1):

Table 1

Type of addition Quantity of additive (% w / w) Thyme viscose Ford 4 («) No addition 0 34,6 Hydroxyethyloellulose 0,5 43,0 1,0 63,0 2,0 125,0 Methylhydroxypropyloeluloza 0,5 48,0 (Metooel ) 1,0 58,0 2,0 95,0 3,0 194,0 Carboxymethylo-cellulose 0,5 48,6 1,0 116,0 2,0 239,0 Smooth teo flour 50 ° C - 30 minutes 1,0 34.6 70 ° C - 30 minutes 1.0 161.0 Potato starch 50 ° C - 30 minutes 1.0 33.2 70 ° C - 30 minutes 1.0 62.4

In the application of cinnamon and poppy seeds, the reactivity from the original 85 s at 100 ° C to 97 s is reduced. Example 2 To a batch of 150 g urea-formaldehyde resin with 20 wt. dispersions of vinyl acetate ethers with a total content of 70 wt. of dry matter prepared with a 2: 1 molar ratio of formaldehyde to urea is further adjusted by the addition of 25 wt. urea as an aqueous solution of kono. 70 wt. at 50 ° C (resulting in a molar ratio of formaldehyde to urea of 1.167). After one hour, the sample is cooled and has the following parameters: free formaldehyde content = 0.27 9 ° wt .; reactivity (gelatin) at 100 ° C e 81 s; 4 210 582 cleavable formaldehyde = 0.64 mg / g and Ford viscosity 4 = 45 a. starch at 50 ° C, the results are as follows after two hours of reactors (Table 2):

Table 2

Addition of starch (# mass) Formaldehyde content Reactivity («) Viscosity <() Free (% w / w) Cleavable (mg / g) 0 0,27 0,614 81 45 1,0 0,31 0,450 76 52 2,0 0,28 0,314 78 56 3.0 0.09 0 ^ 300 77 66 If together with 25 wt. urea is added to the 0.5 poppy solution at 50 ° C, after 2 hours the results are as follows (Table 3): up to 3.0% by weight. Table 3 Addition of Poppy Formaldehyde content Reactivity Viscosity (% w / w) Free (% w / w) wettable (mg / g) (-) (e) 0 0.27 0.614 81 45 0.5 0.41 0.502 86 55 1, 0 0.43 0.570 90 77 2.0 0.68 0.380 107 136.5 3.0 1.05 0.40 95 209 In both cases and before the application of starch, the torture has dissolved in water (needed to prepare an aqueous solution) % by weight of urea by adding urea to the precondensate in solid form. In the case where starch is applied without boiling, the train is 3% by weight. only increases by 7 e and with flour only by 15 s. Example 3

The condensate and / or polycondensate prepared by condensation of formaldehyde with melamine containing 5 moles of unreacted formaldehyde and a content of 45 wt. solids and 4 moles of solid urea and 0.2 moles of hexamethylenediamine are added at 25 ° C for 1 h in the presence of 2.0 wt% sodium hydrophosphate. Hexamethylenediamine is added to 5,210,502 in a solution after 30 min of urea condensate reaction. The resulting molar ratio of formaldehyde to urea is 1.15 &lt; tb &gt; &lt; tb &gt; &lt; tb &gt; ______________________________________ &lt; tb &gt; ______________________________________ &lt; tb &gt; carboxymethyl cellulose. EXAMPLE 4 A urea-formaldehyde condensate prepared with a molar ratio of formaldehyde to urea of 1.15 and a viscosity of 60 s according to Ford 4 and reactivity of 89 s, with a free formaldehyde content of 0.12% by weight of formaldéhyde released 0.53 toe / St then add 1 wt. calcium chloride and 1.0 wt. hydroxyethyloelluloses. This treatment results in an increase in viscosity to 86 s, while increasing the bond strength by 10 $ compared to a sample without additions (with reference sample).

The free formaldehyde content is 0.1% by weight. and the content of formaldéhyde released is 0,5 tag / β of cured resin.

Claims (3)

SUBJECT OF THE INVENTION A process for the production of viscosity-controlled aminoformaldehyde condensates and / or polycondensates, in particular based on urea-formaldehyde element with a molar ratio of formaldehyde to urea of 1.01 to 1.29, characterized in that the viscosity is controlled by additions of 0.1 to 10, and preferably 1-3% by weight of water-soluble or swellable derivatives. cellulose and / or starch, calculated on the weight of the final product. 2. A process as claimed in claim 1, wherein hydroxyalkylo-cellulose and / or carboxyalkyl cellulose are used as the o-cellulose derivative. 3. A method according to claim 1, wherein said starch derivative is potato starch, rice starch and / or cereal flour.