Binder for cellulose-containing materials

Abstract

The invention relates to a binder for cellulose-containing materials which contains a) hydroxyaldehyde, b) a protein-containing component of animal origin and c) a component comprising phenolic oligomers. The invention likewise relates to the use of the binder according to the invention for producing a composite material, to a process for producing a composite material and to a composite material obtainable by the process according to the invention.

Claims

1. Binder for cellulose-containing materials containing a) hydroxyaldehyde, b) protein-containing component of animal origin and c) phenolic oligomer-containing component, wherein the phenolic oligomer-containing component has a weight-average molar mass in the range from 1000 g/mol to 5000 g/mol and the phenolic oligomer-containing component is Kraft lignin.

2. The binder according to claim 1, in which the hydroxyaldehyde is an α-hydroxy-aldehyde.

3. The binder according to claim 1, in which the hydroxyaldehyde in situ is formed from a polyol with at least two OH groups.

4. The binder according to claim 3, which is obtained by mixing: 1-30 percent by weight of the polyol; 0.5-10 percent by weight of an oxidizing agent; 1-20 percent by weight of the protein-containing component of animal origin (dry matter); 1-20 percent by weight of the phenolic oligomer-containing component (dry matter); 0-20 percent by weight of a protein-containing component of plant origin (dry matter); 0-20 percent by weight of casein; and 0-80 percent by weight of water and, the mixture obtained is optionally dried.

5. The binder according to claim 1, which has at least two of the following components: 5-25 proportion by weight of the hydroxyaldehyde; 5-25 proportion by weight of the protein-containing component of animal origin (dry matter) 4-40 proportion by weight of the phenolic oligomer-containing component (dry matter); 1-25 proportion by weight of a protein containing component of plant origin (dry matter); and 0-40 proportion by weight of casein.

6. The binder according to claim 1, in which the protein-containing component of animal origin contains hemoglobin.

7. The binder according to claim 1, wherein the phenolic oligomer-containing component has a weight-average molar mass in the range from 2000 to 3000 g/mol.

8. The binder according to claim 1, further containing d) protein-containing component of plant origin.

9. The binder according to claim 8, wherein the protein-containing component of plant origin is a plant stillage.

10. The binder according to claim 1, wherein the protein-containing component of animal origin is casein.

11. The binder according to claim 1, further containing an amide.

12. The binder according to claim 1, further containing a carboxylic acid, a carboxylic acid salt and/or a carboxylic acid anhydride.

13. The binder according to claim 1, which has a pH value in the range from 7 to 12.

14. The binder according to claim 1, containing less than 5.0 wt.-% of ammonium salts.

15. The binder according to claim 1, containing less than 2.0 wt.-% of formaldehyde.

16. A composite material comprising the binder of claim 1 and at least one cellulose-containing material.

17. A process for producing a composite material, said process comprising combining said binder according to claim 1 with a cellulose-containing material at a temperature in the range from 100 to 250° C. and at a pressure of 1 to 250 bar.

18. A composite material, which is obtained by the method according to claim 17.

Description

EXAMPLE 1

Chipboard

(1) A one-component binder with composition 1 according to the above table was formed by mixing the starting components indicated. For the production of a chipboard, pine wood chips (screen fraction >0.6 mm×4 mm, 4 wt. % moisture content) were mixed with the binder by spraying in a drum mixer to achieve uniform wetting of the chips. The mass fraction of the binder was 8% by weight.

(2) The chips wetted with the binder were evenly scattered onto a press plate which was wetted with a commercially available release agent so that a chip cake was formed. The chip cake was pre-pressed by hand and then pressed in a laboratory plate press at a temperature of 200° C. for a period of 120 s at a pressure of 150 bar. The pressing time was measured from the time the pressure was completely built up. A chipboard with a thickness of 12 mm was obtained, i.e. the pressing time was 10 s/mm board thickness.

(3) For the obtained chipboard the following technical values were determined according to DIN EN 312-1 (2010):

(4) Thickness swelling: 14%

(5) Bending strength: 15.2 N/mm.sup.2

(6) Bending modulus of elasticity: 2954 N/mm.sup.2

(7) Transverse tensile strength: 0.62 N/mm.sup.2

(8) This means that the technical values for class P3 chipboard according to DIN EN 312-1 (2010) have been achieved.

(9) The formaldehyde emission of the chipboard obtained was determined using the chamber method according to DIN EN 717-1 (2006). This was 0.024 mg/m.sup.3 after 12 h, 0.019 mg/m.sup.3 after 24 h and 0.005 mg/m.sup.3 after 240 h. Surprisingly, the natural formaldehyde emission of untreated pine wood chips was even 6 times lower.

EXAMPLE 2

Oriented Strand Board Plate

(10) A one-component binder with composition 2 according to the above table was formed by mixing the starting components indicated. To produce a 12 mm thick OSB (Oriented Strand Board) board, wood flakes (2-4% moisture content by weight) were wetted with the binder using a drum process. The mass portion of the binder was 8% by weight.

(11) The flakes wetted with the binder were scattered to form a cake and placed in a board press for pressing. The cake thus prepared was then pressed at a temperature of 200° C. and a pressure of 165 bar over a period of 120 s to form an OSB board.

(12) The technical values for class P3 OSB boards according to DIN EN 312-1 (2010) were achieved.

EXAMPLE 3

Thin Chipboard

(13) A one-component binder with composition 3 according to the above table was formed by mixing the starting components indicated. To produce a thin chipboard (3.0 mm) with a specific weight of 820 kg/m.sup.3 according to the Mende process on a calender (AUMA 30), pine wood chips (screen fraction >0.6 mm x 4 mm) were wetted with 115 kg of binder (corresponding to a binder content of 14% by weight) in a drum mixer (Lödige).

(14) The 3.0 mm thick board was formed over 30 s at 140 bar pressure and a temperature of 175° C. The feed rate of the calender plant was 22 m/m in.

(15) The technical values for class P3 thin chipboard according to DIN EN 312-1 (2010) were achieved.

EXAMPLE 4

Chipboard

(16) A one-component binder with the composition 4 according to the above table was formed by mixing the indicated starting components. To produce a chipboard (of a thickness of 22 mm), pine wood chips (sieve fraction >0.6 mm×4 mm, 2.5% by weight of moisture content) were mixed with the binder by spraying and a chip cake was formed. The mass fraction of the binder was 8% by weight.

(17) The chip cake was pressed at a temperature of 200° C., a pressure of 155 bar and a pressing time of 12 s/mm board thickness in a single-opening press.

(18) The technical values for class P3 chipboard according to DIN EN 312-1 (2010) were achieved.

EXAMPLE 5

Medium Density Fibreboard

(19) A one-component binder with composition 5 according to the above table was formed by mixing the starting components indicated. To produce a medium density fiberboard (MDF board), pine chips defibered by a refiner were dried to a moisture content of about 1% by weight. The binder was applied by drum gluing in a spray process. The mass proportion of the binder was 8% by weight.

(20) The wetted wood fibers were pressed at 185° C. and a pressure of 140 bar. The pressing time in a continuous press was 8 s/mm board thickness. A 6 mm board was produced in 48 s.

(21) The technical values for MDF boards of class P3 according to DIN EN 312-1 (2010) were achieved.

EXAMPLE 6

Plywood Panel

(22) A two-component binder with composition 6 according to the above table was formed by mixing the starting components indicated. The binder component A contained glycerol, hydrogen peroxide, Saval protein concentrate, plant stillage and flour and the binder component B contained Kraft lignin, fluorocarbonate, melamine, glyoxal and resorcinol.

(23) For the production of plywood boards (laminated wood), binder component A was rolled onto one side of a 2 mm thick birch veneer, which was stretched with type 405 wheat flour in order to increase the solids content and prevent the binder from “piercing”. The application rate of binder component A was 80 g/m.sup.2. Binder component B was rolled onto one side of a second birch veneer. The application rate of binder component B was 40 g/m2. Then the top surfaces of the two veneers, to which the binder components were applied, were placed crosswise on top of each other and pressed together at a pressing temperature of 140° C. and a pressure of 65 bar for a period of 120 s.

EXAMPLE 7

Veneered Surface

(24) A one-component binder with the composition 7 according to the above table was formed by mixing the indicated starting components. To produce a veneered surface, the binder was rolled onto both sides of a chipboard with 80 g/m2 as a carrier board using a double-sided glue application roller. The glued carrier board was placed on oak veneer with a thickness of 0.8 mm. The upper side was also covered with oak veneer and fed to a short-cycle press. The pressing pressure was 70 N/mm.sup.2 and the pressing time 90 s at 110° C.

EXAMPLE8

Chipboard

(25) A one-component binder with the composition 8 according to the above table was formed by mixing the indicated starting components. To produce a chipboard (of a thickness of 16 mm), pine wood chips (screen fraction >0.6 mm×4 mm, 2-4% by weight of moisture content) were mixed with the binder by spraying and a chip cake was formed. The mass fraction of the binder was 7% by weight.

(26) The chip cake was pressed at a temperature of 210° C. and a pressure of 150 bar with a pressing time of 130 son a single-opening press.

(27) The technical values for class P3 chipboard according to DIN EN 312-1 (2010) were achieved.

EXAMPLE 9

Straw Board

(28) A one-component binder with the composition 9 according to the above table was formed by mixing the indicated starting components. The binder was applied by means of a batch mixer (Lodige) with two dosing nozzles to untreated straw fibers with a length of up to 20 mm (approx. 6% by weight of moisture content). The mass fraction of the binder was 10% by weight.

(29) The wetted straw fibers were pressed at 180° C. and a pressure of 140 bar. The pressing time in a single-opening press was 12 s/mm of board thickness. By means of spacer plates a board of 20 mm of board thickness with a specific weight of 550 kg/m3 was produced.

(30) The following values were determined according to DIN EN 622:

(31) Bulk density: 550 kg/m.sup.3

(32) Transverse tensile strength: 0.58 N/mm.sup.2

(33) Thickness swelling (24 h): 14.3%

(34) Bending strength: 28.2 N/mm.sup.2

(35) The technical values for class P3 fiberboards according to DIN EN 622 have thus been achieved.

(36) Thus, the binder according to the invention also enables the production of composite materials based on cellulose-containing natural products such as straw, whose surface has a silicate or wax layer. This is particularly surprising because conventional binders, for example based on am inoplastics, are not suitable for processing such natural products.

(37) Instead of straw, other cellulose-containing fibers may be used, preferably based on young plants or annual plants or shredded husks such as corn cobs, peanut shells and the like, and recycled paper.

EXAMPLE 10

Fiberboard

(38) A one-component binder with the composition 10 according to the above table was formed by mixing the indicated starting components. For the production of a fiberboard, wood chips defibered by a refiner were dried to a moisture content of about 4% by weight. The binder was sprayed onto the wood fibers using a ploughshare mixer and airless spraying. The mass fraction of the binder was 8% by weight. The wetted wood fibers were pressed at 200° C. using spacer plates to form a 20 mm thick board with a specific weight of 120 kg/m.sup.3. The pressing time was 160 s and thus 8 s/mm board thickness.

(39) The bending strength of the fiberboard obtained in accordance with DIN EN 622-4 was 1.3 N/mm.sup.2. Thus, the technical values for porous wood fiber boards for exterior use according to DIN EN 622-4 were achieved.

(40) The emission of volatile organic compounds (VOCs) from the fiberboard obtained after 5 h, 24 h and 48 h is shown in the following table:

(41) TABLE-US-00004 after 5 h after 24 h after 48 h VOC (<C6) 34 μg/m.sup.3 46 μg/m.sup.3 65 μg/m.sup.3 VOC (C.sub.6-C.sub.16) 34 μg/m.sup.3 29 μg/m.sup.3 27 μg/m.sup.3 VOC (total) 68 μg/m.sup.3 75 μg/m.sup.3 92 μg/m.sup.3