Binder composition in wooden composite boards

Abstract

The present invention relates to a binder composition, in particular for wooden composite boards, obtainable from a binder composition, in particular for wooden composite boards obtainable from at least one polymer adhesive, at least one polyalcohol compound, at least one compound of the general formula (I)
R.sub.aSiX.sub.(4a)(I),
or the general formula (II)
O.sub.bX.sub.c(OH).sub.dR.sub.eSiO(4-b-c-d-e)/2(II). The present invention relates also to a wooden composite board containing said binder composition.

Claims

1. A binder composition, in particular for wooden composite boards obtainable from at least one polymer adhesive selected from a formaldehyde adhesive, polyurethane adhesive, epoxide resin adhesive, or polyester adhesive, at least one polyalcohol compound selected from an alditol, one compound of the general formula (I)
R.sub.aSiX.sub.(4a)(I), or the general formula (II)
O.sub.bX.sub.c(OH).sub.dR.sub.eSiO(4bcde)/2(II), wherein X is H, OH or a hydrolysable moiety selected from the group comprising halogen, alkoxy, carboxyl, amino, monoalkylamino or dialkylamino, aryloxy, acyloxy, alkylcarbonyl, R is a non-hydrolysable organic moiety R selected from the group comprising substituted and unsubstituted akyl, substituted and unsubstituted aryl, substituted and unsubstituted alkenyl, substituted and unsubstituted alkinyl, substituted and unsubstituted cycloalkyl, which may be interrupted by O or NH, and wherein R has at least one functional group Q selected from a group comprising an epoxide, hydroxyl, ether, amino, monoalkylamino, dialkylamino, substituted and unsubstituted aniline, amide, carboxyl, alkinyl, acryl, acryloxy, methacryl, methacryloxy, mercapto, cyano, alkoxy, isocyanate, aldehyde, alkylcarbonyl, acid anhydride and/or phosphoric acid group, and R and X can be in each case the same or different from each other, and a=0, 1, 2, 3, in particular 0 or 1, b, c, d=0 or 1, and e=1, 2, 3, wherein at least two different compounds of the general formula (I) and/or (II) are used, and wherein a first compound corresponds to the formula SiX.sub.4 with X being OH or alkoxy and a second compound corresponds to the formula R.sub.aSiX.sub.(4a) with a=1 or 2, wherein X being OH or alkoxy, R is methyl, ethyl, n-propyl or n-butyl and Q is a glycidyl or glycidyloxy group, an alkoxy, an amino or an isocyano group.

2. The binder composition according to claim 1, wherein the at least one alditol is selected from the group containing tetravalent, pentavalent, and hexavalent alditols.

3. The binder composition according to claim 1, wherein the at least one alditol comprises a tetravalent alditol.

4. The binder composition according to claim 1, wherein X is selected from a group comprising fluorine, chlorine, bromine, iodine, C.sub.1-6-alkoxy, in particular methoxy, ethoxy, n-propoxy and butoxy, C.sub.6-10-aryloxy, in particular phenoxy, C.sub.2-7-acyloxy, in particular acetoxy or propionoxy, C.sub.2-7-alkylcarbonyl, in particular acetyl, monoalkylamino or dialkylamino with C.sub.1 to C.sub.12, in particular C.sub.1 to C.sub.6.

5. The binder composition according to claim 1, wherein R is selected from a group comprising substituted and unsubstituted C.sub.1-C.sub.30-alkyl, in particular C.sub.5-C.sub.25-alkyl, substituted and unsubstituted C.sub.2-C.sub.6-alkenyl, substituted and unsubstituted C.sub.2-C.sub.6-alkinyl and substituted and unsubstituted C.sub.6-C.sub.10-aryl.

6. The binder composition according to claim 1, wherein R is selected from a group comprising methyl, ethyl, n-propyl, isopropyl, n-butyl, s-butyl, t-butyl, pentyl, hexyl, cyclohexyl, vinyl, 1-propenyl, 2-propenyl, butenyl, acetylenyl, propargyl, phenyl and naphthyl.

7. The binder composition according to claim 1, wherein the at least one functional group Q selected from a group comprising an epoxide, hydroxyl, ether, acryl, acryloxy, methacryl, methacryloxy, amino, alkoxy, cyano and/or isocyano group.

8. The binder composition according to claim 1, wherein the at least one functional group Q is an epoxide, in particular a glycidyl or glycidyloxy group, an alkoxy, an amino or an isocyano group.

9. The binder composition according to claim 1, wherein the polymer adhesive is a polyurethane adhesive on the basis of polydiphenyl methane diisocyanate (PMDI).

10. The binder composition according to claim 1, wherein the at least one alditol comprises a pentavalent alditol selected from the group consisting of arabitol, adonitol, and xylitol.

11. The binder composition according to claim 1, wherein the at least alditol compound comprises a hexavalent alditol.

12. The binder composition according to claim 1, wherein the molar ratio of the first and the second compound is selected within a range of from 0.1:1 to 1:1 mol.

13. A method for obtaining a binder composition according to claim 1 comprising the steps: providing at least two different compounds of the general formula (I) and/or (II); addition of at least one polyalcohol compound selected from an alditol; addition of at least one catalyst, in particular an acid, to the mixture of at least two different compounds of formula (I) and/or (II) and at least one polyalcohol compound; precipitation and separation of the reaction mixture of at least two different compounds of the formula (I) and/or (II) and at least one polyalcohol compound, and addition of at least one polymer adhesive system selected from a formaldehyde adhesive, polyurethane adhesive, epoxide resin adhesive, or polyester adhesive to the separated reaction mixture of at least two different compounds of formula (I) and/or (II) and at least one polyalcohol compound, and wherein a first compound corresponds to the formula SiX.sub.4 with X being OH or alkoxy and a second compound corresponds to the formula R.sub.aSiX.sub.(4a) with a =1 or 2, wherein X being OH or alkoxy, R is methyl, ethyl, n-propyl or n-butyl and Q is a glycidyl or glycidyloxy group, an alkoxy, an amino or an isocyano group.

14. A wooden composite board, in particular a wood chip board and/or wood fiber board, comprising at least one binder composition according to claim 1.

Description

DETAILED DESCRIPTION

(1) The invention will be explained in detail below by means of an example.

EXAMPLE

(2) A mixture of 34.2 g sorbitol (50 w/% in demineralized water) in 4 g para-toluol sulfonic acid is added to a mixture consisting of 20.33 g tetraethylorthosilicate (0.1 mol) and 139.2 glycidyl oxypropyltriethoxysilane (0.5 mol). Hereby, a hydrolysis of the silane mixture and a reaction with the sorbitol takes place, wherein the condensation degree is kept low on purpose. The reaction process and the condensation degree are followed up by SiNMR measurements.

(3) After a stirring time of 4 hours, a mixture of 136.8 g demineralized water and 34 g sodium glycerol phosphate is added to the above reaction mixture. Said mixture is stirred for further 60 minutes.

(4) After a resting time of about 1 hour a two-phase mixture is formed. The lower aqueous phase containing the reaction product of silane and sorbitol is separated from the upper alcoholic phase.

(5) The aqueous binder phase containing the reaction product of silanes and sorbitol is added to 428 g PMDI glue. This mixture has to be homogeneous. The aqueous binder phase is added to PMDI as binder in concentrations of 5 wt % and 20 wt %.

(6) Subsequently, the binder composition is applied onto a plywood pattern or a plywood sample. 1 ml of the solution was applied in each case onto a cut surface of the wood sample and dried in a drying oven at 100 C. for 15 minutes. Subsequently, the penetration depth of the solution was determined visually. Five wood examples were tested per experiment.

RESULTS

(7) Pure PMDI glue penetrates far into the plywood sample when using this method (curing at 100 C. for 15 minutes) and thus disappears at the adhesive surface. The PMDI glue sinks thereby very far into the plywood sample, what is detectible on the front side as well as on the back side of the plywood sample.

(8) In contrast, when adding 5 wt % of the reaction product of silane and sorbitol to the PMDI glue a different result is obtained after curing at 100 C. for 15 minutes. On the front side as well as on the back side there are no penetration tracks of the modified glue to be detectable when increasing the amount of reaction product of silane and sorbitol to 20 wt % and curing at 100 C. for 15 minutes the glue even remains completely on the surface and appears to foam slightly.

(9) The results show clearly that by adding a reaction mixture of modified silanes with a polyalcohol such as sorbitol to a PMDI glue an absorption or diffusion of the PMDI glue into the wood fibers can be prevented whereby a reduction of the required binder amount in the production process of wooden composite boards is possible.