FI71688B - REFERENCE FORMAL TRAINING WITH TRAEMATERIAL MEDICINE LITEN FORMALDEHYDAVGIVNING - Google Patents

Description

1 71688

This invention relates to the production of wood materials 5 which have a very low formaldehyde secretion and which have been prepared by gluing the corresponding raw materials with condensation products of urea and / or melamine and / or phenol and formaldehyde. / optionally mixed with another 10 aldehyde.

Characterization of known technical solutions.

It is known that condensation products of formaldehyde with urea or melamine both during the curing process and also at the end of curing release formaldehyde. In particular, the formaldehyde insulation of glued products, which can be caused by residual free or hydrolytically formed formaldehyde, is of great importance to the handler and user of such materials, as it can cause health damage. It is further known that the subsequent release of formaldehyde from wood materials can be reduced by 50-75% by pretreating the wood raw materials to be glued with an aqueous dispersion of a water-dispersible polymer or wax and a water-miscible substance to bind formaldehyde. Despite the considerable advantages of this process compared to previous attempts to reduce post-formaldehyde separation from wood materials, it has proved disadvantageous that, for example, in chipboard manufacturing, there is a significant increase in costs due to the composition and amount of additives. Another disadvantage is that the effect of the additives is linked to their pre-injection of 2 71688 wood raw material and the method is therefore only partially available in plants normally used for the production of particle board without modification (DE-AS 2 740 207).

5 There is a need to develop a method for the production of wood materials with very low formaldehyde secretion, which method does not significantly increase the cost of manufacturing the material and which is universally useful.

This object is solved by a process for the production of wood materials, in particular particle board, by gluing the corresponding raw materials, preferably wood chips with condensation products of urea and / or melamine and / or phenol and formaldehyde, optionally mixed with another aldehyde / according to the invention. condensation products suitable for receiving formaldehyde from formaldehyde-binding monomers, preferably urea, melamine or phenol, and aldehydes, preferably formaldehyde, optionally in association with formaldehyde-binding monomers, are added to the substance or binder.

The condensation products made of urea and / or melamine and / or phenol used for gluing according to the invention are common products, in particular those used as binders in the production of wood materials, which are commercially available both as aqueous solutions and also as powders. The molar ratio of formaldehyde to urea in the condensates of these compounds is usually 1.2 to 1.7. Even when the condensate contains other constituents, such as, for example, melararin, phenol or melamine and phenol or aldehydes other than formaldehyde, the ratio between the carbonyl group or its reactive groups remains in the range of 3 71688, which is the basis for said molar formaldehyde and urea. .

According to the invention, the condensation products used for the production of wood materials with very low formaldehyde insulation from formaldehyde-binding monomers, such as urea, melamine or phenol and formaldehyde or other aldehydes, have a reduced ratio of . The molar ratio of urea / formaldehyde condensates used for the production of wood slabs with very low formaldehyde secretion is expediently 1: 0.3 to 1: 1.0. If the amount of formaldehyde is further reduced by 15, a loss of strength in the particle board under otherwise the same gluing conditions cannot be avoided. When raising the formaldehyde content above said value, it was necessary to use larger amounts of condensate product in order to achieve a comparable effect, which, however, can be reduced by the simultaneous addition of a formaldehyde-binding monomer.

In addition to formaldehyde bonding, their storage stability is an essential condition for the usability of condensation products. The 25 experiments described in the use examples were performed on products that are not commercially available. Formaldehyde-binding condensation products can be added to both the binder and the raw material to be glued. In the case of chipboard production, it is then possible to add the condensate-30 either to the binder used for gluing, i.e. to the gluing member, or to spray it on the non-gluing chips. The amount of addition depends on the formaldehyde secretion of the binder used and the magnitude of the desired effect. If a chipboard adhesive with FESYP formaldehyde values of 0.06 and 0.03 is used as the binder, then 4,71688 requires a larger amount of the additive according to the invention for the first adhesive in order to achieve the same final value of formaldehyde secretion.

Example 1 (Comparative Example) 5 From a commercially available conventional urea / formaldehyde binder, an adhesive broth having 100 kg of water, 25 kg of paraffin emulsion (40%), 6 kg of 10% NH 4 Cl solution and 4 kg of glue of the following composition is prepared and it was placed in an amount of only 8% resin, calculated from Atro dried wood, on pine chips (length: 15-20 mm, width: 3-5 mm, thickness: 0.2-0.4 mm). The glued chips were formed under the following conditions

compression temperature 160-65 ° C

2 compression pressure 1.5 N / mm compression time 7 min for 20 mm thick chipboards with the following properties determined by 20 conventional methods: density g / cm 0.610 flexural strength N / mm ^ 25.1 transverse tensile strength V 20 N / mm2 0.63 25 expansion 2 h after α,% 3.3 formaldehyde excretion FESYP,% 0.035

Example 2 A urea / formaldehyde condensate with a molar ratio of 1: 0.5 was used to prepare particle boards according to Example 1. Conditions other than Example 1 and test results are given in Table 1.

5,71688

table 1

Addition% Atro per wood Particleboard properties method of administration 5 Glue additional density- Fold. Crosswise. Swelling- FESYP- (resin and strong tensile 2 h formal) g / cm3 _? After food. dehyd.

N / mnr N / tm%

Pre-shower 8 2.3 0.611 25.5 0.65 3.4 0.01 call 10 Broth 8 2.3 0.612 25.9 0.64 3.5 0.01

Broth 6.6 2.3 0.614 24.5 0.60 3.6 0.01

Example 3 A mixture of 40% by weight of the adhesive according to Example 1, 40% by weight of urea and 20% by weight of water was used as an additive in the manufacture of particle board according to Example 1. Conditions other than Example 1 and the test results are given in Table-20 and 2.

Table 2 25 Addition% Atro per wood Particleboard aninities administration method

Glue additional dense- Fold. Crosswise. Swell- FESYP- (resin and strong tensile 2 h formal) g / an3 _? After food. dehyd.

N / mrfr N / hm% 30

Pre-spraying 8 2.4 0.607 26.2 0.67 3.1 0.01

Pre-spraying 7.4 2.4 0.607 24.9 0.61 3.3 0.01 6 71688

Example 4

A condensation product prepared from phenol and a 37% aqueous solution of formaldehyde in an alkaline medium with a molar ratio of 1: 0.7 was dissolved in 5 urea so that the molar ratio of phenol to urea is 1: 0.5. The product obtained is used in the manufacture of particle board according to Example 1 at a pre-injection gluing of 2.2% Atro per chip. Particleboards prepared in this way had the following properties: density, g / cm3 0.604 2 flexural strength, N / mm 25.2 2 transverse tensile strength, N / mm 0.62 expansion after 2 h, ma-% 3.7 15 formaldehyde release FESYP ma-% 0.01

Example 5

A mixture of 70% by weight of melamine / formaldehyde condensation product (solids content 56.8% by weight) in a molar ratio of 1: 1.7 and 30% by weight of urea was used in the chipboard preparation according to Example 1 as an additive for chip injection (3 .3% Atro per chip).

Particleboards prepared in this way had the following properties: 25 density, g / cm "* 0.610 2 flexural strength, N / mm 25.1 2 transverse tensile strength, N / mm 0.79 swelling after 2 h ma-% 3.7 formaldehyde release FESYP ma-% 0.01