FORMALDEHYDE-FREE WOOD BINDER

Abstract

The formaldehyde-free binder for materials containing cellulose contains a hydroxy aldehyde resin polycondensed with an ammonium salt, the resin being obtained, in especially preferred embodiments, from glycerin, in situ, with the aid of hydrogen peroxide. A protein component consisting of animal blood is added. The binder is urea-free and can be used as a one-component or two-component binder. It binds materials such as wood, paper and other natural fibres to form high-quality composite material products.

Claims

1-20. (canceled)

21. Binder for cellulose-containing materials, which comprises a hydroxyaldehyde resin which is condensed with an ammonium salt.

22. Binder according to claim 21, wherein the hydroxyaldehyde for the binder resin is carbohydrate aldehyde.

23. Binder according to claim 22, wherein the hydroxyaldehyde for the binder resin is glyceraldehyde.

24. Binder according to claim 21, wherein the hydroxyaldehyde is formed from an at least difunctional hydroxy compound with an oxidizing agent.

25. Binder according to claim 24, wherein the oxidizing agent is a peroxide.

26. Binder according to claim 21, which is free of urea.

27. Binder according to claim 21, which comprises a protein component.

28. Binder according to claim 27, wherein the protein component is based on animal blood.

29. Binder according to claim 27, wherein the protein component comprises hemoglobin from animal blood or protein concentrate from animal blood.

30. Binder according to claim 21, wherein the ammonium, salt is a single salt or a mixture of salts selected from the group of ammonium sulfate, ammonium alums, ammonium lignosulphonate and ammonium hydrogen phosphate.

31. Binder according to claim 21, wherein the ammonium salt is at least 50 wt.-% relative to all nitrogen-containing components capable to cross-link with hydroxyaldehydes without considering the optionally present protein component.

32. Binder according to claim 31, wherein the weight portion of the sum of all nitrogen-containing components which are capable to cross-link with hydroxyaldehydes, including the ammonium salt and excluding proteins, is at least 15 wt.-% of the binder.

33. Binder according to claim 21, which is a two or multi-component binder, the components of which are mixed directly before its use or are applied separately.

34. Composite material product obtainable by binding a cellulose-containing starting material with a binder according to claim 1 and shaping to a product.

35. Composite material product according to claim 34, wherein the starting material is wood and/or paper.

36. Composite material product according to claim 34, which is plate-shaped.

37. Process for preparing the binder according to claim 21, wherein an ammonium salt is mixed with a hydroxyaldehyde or an ammonium salt is mixed with an at least difunctional hydroxy compound and an oxidizing agent.

38. Process according to claim 37, wherein water in an amount of at most 48 wt.-%, at least one ammonium salt, glycerol, hydrogen peroxide, the protein component, optionally an additional amine or amide as well as optionally additives and auxiliaries are mixed.

39. Process for binding cellulose-containing materials, wherein hydroxyaldehyde is condensed with an ammonium salt.

40. Process according to claim 39, wherein the bound cellulose-containing material is shaped to a composite material product.

Description

EXAMPLES

[0064] Nine binder glues are prepared. The compositions are shown in Table 1.

TABLE-US-00001 TABLE 1 Example 1 2 3 4 5 6 7 8 9 1) 60% aqueous salt solution for . . . wt.-% of the binder glue Ammonium sulfate 41.4 9.3 28.8 15.0 9.6 25.8 32.4 Ammonium alum 41.4 9.3 9.6 2) binder glue with following components: Solution from 1) 69 69 31 48 25 32 43 54 25 H.sub.2O (wt.-%) Further N-components: Ammonium 14 20 25 10 40 lignosulphonate Ammonium hydrogen 20 phosphate Melamine 20 Glycerol (85%) 15 15 38 12 10 40 10 8 15 Hydrogen peroxide 12 12 20 14 10 20 12 6 10 (35%) Protein component 4 4 8 10 10 8 10 4 10 (solid) Additives: Surfactant, Schwego 2 1 1 foam 6305 (with polyasparaginate) Paraffin solution 1 1 2 1 2 (ethanolic) Hydro Wax company Sasol Gelatin 3 (all values are in wt.-%)

[0065] Firstly, a 60 (wt.-)% aqueous ammonium salt solution is prepared if the composition comprises ammonium sulfate or ammonium aluminium sulfate dodecahydrate (or another ammonium alum). At higher amounts of ammonium salt, this may take place at elevated temperatures. In Table 1 under 1), the amounts of ammonium sulfate and/or ammonium alum in the binder glue are given which are obtained when the amount of the aqueous solution from 1) stated below is used for the composition.

[0066] In Example 6, which does neither comprise ammonium sulfate nor ammonium alum, the ammonium lignosulphonate is initially dissolved in water and then the further components are added.

[0067] The binder glue examples stated in Table 1 may be used in manifold ways. They bind wood, paper and other cellulose-containing natural fibers as well as synthetic pulp products. Some possibilities of use are stated in the subsequent application examples.

APPLICATION EXAMPLES

Application Example 1

[0068] In order to produce a chipboard, spruce wood chips having a residual moisture of 2% are mixed with a formaldehyde-free binder according to the invention.

[0069] The weight portion of the chips is 92% (wt.-%).

[0070] The binder mixture is a one-component mixture. The solids content of all examples is more than 50%, i.e. the water content of the binder glue is less than 50%. All inorganic and organic components of the glue including glycerol, excluding hydrogen peroxide and water, are taken into consideration for the solids content. The mixing is carried out in a spraying process in order to attain a uniform wetting. The binder content is, based on the solids content, 8% of the specific weight of the board.

[0071] The chips wetted with binder are uniformly spread onto a press plate so that a splinter cake is formed. The splinter cake is compressed in a plate press at a temperature of 180 C. for a period of 180 seconds so that a chipboard with a thickness of 12 mm is formed. The compressing pressure is set to 150 bar. A chipboard produced in that way is free of emissions.

[0072] The technical values of DIN ISO EN 312:210 type P2 were met.

[0073] Variation

[0074] Up to a maximum of 10 wt.-% of a 1 molar solution of potassium hydroxide (KOH), sodium hydroxide (NaOH) or calcium hydroxide (Ca(OH).sub.2) may be added to the binder.

Application Example 2

[0075] In order to produce a 12 mm thick OSB (oriented strand board), flakes with a wood moisture of 2-4% are required which are wetted with a one-component binder from the example part (see Tab. 1) in a tumbling process.

[0076] Based on the specific weight of the flakes and the solids content of the binder, 10% of binder is processed. The flakes wetted with the liquid are spread to a cake and are put into a plate press for compressing. Afterwards, the flake cake is compressed to an OSB plate at a temperature of 180 C. and at a pressure of 165 bar for a period of 180 seconds. The technical values of DIN ISO EN 312:210 type P2 were met.

Application Example 3

[0077] In order to produce a thin chipboard, e.g. according to the Mende-process on a calender, with a specific weight of 780 kg/m.sup.3, the chips are wetted with 143 kg of binder formulation from the example part in a Loedige drum mixer. In order to meet the technical values of the EN standard, the binder content, based on the solids content, needs to reach 11%.

[0078] The 3.0 mm plate is compressed for a period of time of 30 seconds at a pressure of 140 bar and a temperature of 175 C. The technical values of DIN ISO EN 312:210 type P2 were met.

Application Example 4

[0079] A splinter cake is formed to produce a chipboard. The weight portion of wet chips is 92% with a residual moisture of 2%. A binder glue with a water content of <40% is selected. The binder is applied by a spraying process. The binder content, based on the solids content, is 8% of the specific weight of the board. The splinter cake is compressed in a single opening press at a temperature of 200 C. and a pressure of 155 bar and a compressing time of 12 seconds per mm board thickness. The technical values of DIN ISO EN 312:210 type P2 were met.

Application Example 5

[0080] In order to produce an MDF board, the wood fibers (1% wood moisture) dried over a refiner are wetted with a one-component formaldehyde-free binder according to the invention by means of drum gluing in a spraying process.

[0081] The weight portion of wood fibers is 90%; the binder content is 10% based on the solids content.

[0082] The wetted wood fibers are compressed at 185 C. and a pressure of 140 bar. The compressing time in a continuous press is 8 seconds per 1 mm board thickness. (A 6 mm board is produced in 48 seconds)

Application Example 6

[0083] The binder glue of Example 1 is produced in a two-component way.

[0084] Glue component 1: Mixture of aqueous ammonium alum solution and hydrogen peroxide;

[0085] Glue component 2: Mixture of 85% glycerol and protein concentrate of company Saval.

[0086] mm thick birch veneers are provided to produce plywood boards (laminated wood). Glue component 1 which is very highly fluid is sprayed on one side of a birch veneer. Onto another surface of a second birch veneer, glue component 2 is rolled on with an applied quantity of 40 g/m.sup.2. Subsequently, both surfaces of the birch veneers are put onto each other cross-wise and are compressed with each other at a compressing temperature of 170 C. and a pressure of 65 bar for a period of time of about 120 seconds.

Application Example 7

[0087] In order to produce a veneered area, a one-component binder according to the invention is applied with 80 g/m.sup.2 onto a carrier plate, a chipboard in this case, by means of a one-sided glue application roller.

[0088] The veneer, in this case an oak veneer with a thickness of 0.6 mm, is put with its whole surface onto the glued carrier plate and is compressed in a veneer press at 70 N/mm.sup.2 pressing pressure for 90 seconds.

[0089] Variation

[0090] Prior to application, the binder is diluted with up to 10 wt.-% of wheat flour or starch (preferably corn or soy starch) in order to increase the solids content and to prevent the so-called glue penetration.

Application Example 8

[0091] A chip cake is formed to produce a 22 mm chipboard. The weight portion of wet chips is 90% with a residual moisture of 2-4%. The solids content of the binder is about 63%.

[0092] The binder content, based on the solids content, is 10% of the specific weight of the board (680 kg/m.sup.3 of the final board, 68 kg solids content of the binder, 108 kg liquid binder).

[0093] The binder is applied in a spraying process.

[0094] The chip cake is compressed in a single opening press at a temperature of 210 C. and a pressure of 150 bar and a pressing time of 220 seconds.

Application Example 9

Straw Board

[0095] A one-component binder according to Example 9 is used.

[0096] The length of the straw fibers should be not more than 20 mm.

[0097] The liquid is applied by means of a Loedige ploughshare mixer.

[0098] The weight portion of straw fibers is 90%;

[0099] the binder, based on the solids content, is 10%.

[0100] The wetted straw fibers are compressed at 165 C. and a pressure of 160 bar. The pressing time in a single opening press is 15 seconds per 1 mm board thickness.

[0101] A lightweight construction board of 30 mm thickness with a specific weight of 280 kg/m.sup.3 was produced.

[0102] Instead of straw, other cellulose-containing fibers (preferably from younger plants) or recycling papers can be used as well.

[0103] Comment:

[0104] Straw boards cannot be adhered with customary urea-formaldehyde-binders because the outer skin of the straw comprises paraffin and exhibits a high separation effect relative to this binder. Therefore, straw boards are produced by means of isocyanates (PDMI).

[0105] The formaldehyde-free binder according to the invention, in particular according Example 9, dissolves the paraffin structure of the straw and enables the cross-linking to give a board.

[0106] Formaldehyde Test:

[0107] A formaldehyde test was carried out in the Institute for Wood Technology Posen.

[0108] Test report No.: 371/2016/S.F. of 25-02-2016.

[0109] The six three-layered chipboards had dimensions of 290 mm290 mm6 mm and were produced with a binder of Example No. 4.

[0110] Three-layered chipboards (EO P1 CE) were tested for 10 days according to EN 717-1:2006 (chamber method).

[0111] The 9 measurements resulted in the following values: 0.022/0.017/0.013/0.008/0.007/0.008/0.008/0.008/0.008 ppm formaldehyde emissions.

[0112] According to the standard (EN 120/CARB standard), the formaldehyde emissions are not allowed to exceed 0.1 ppm (ml/m.sup.3) under these conditions.

[0113] The measured values were far below and are derived from the organic matter of the wood.

[0114] This demonstrates that during setting no cleavage reactions with release of formaldehyde or other detrimental emissions can take place.

[0115] The obtained new board is completely free of formaldehyde emissions according to standard EN 120/CARB standard.