METHOD FOR PRODUCING LIGNOCELLULOSE MATERIALS IN THE PRESENCE OF CAPROLACTAM AND OLIGOMERS OF CAPROLACTAM

Abstract

The present invention relates to a method for producing isocyanate based lignocellulose materials in the presence of caprolactam, oligomers of caprolactam or mixtures thereof. The present invention also relates to the lignocellulose materials thus obtained and their use in furniture construction, housing construction, interior design and exhibition construction.

Claims

1-16. (canceled)

17. A method for producing single or multilayer lignocellulose materials composed of one or a plurality of layer(s) (Lr) and optionally one or a plurality of further layer(s) (FLr) comprising the method steps of (I) mixing of the components into one or a plurality of mixture(s), (II) scattering of the mixture(s) produced in method step (I) to form a mat, (III) precompression of the scattered mat and (IV) heating and pressing of the precompressed mat, wherein the mixture(s) used in method step (1) for the one or a plurality of layer(s) (Lr) comprises lignocellulose particles (component L), caprolactam, oligomers of caprolactam or mixtures thereof (component A), binders based on isocyanate comprising multicore diphenylmethane diisocyanate (component B), water (component C) and optionally one or a plurality of additives (component D).

18. The method for producing lignocellulose materials as claimed in claim 17, wherein the mixture of the layer (Lr) comprises lignocellulose particles (component L) and 0.5 to 10 wt % of component B, 3 to 16 wt % of component C, and 0 to 30 wt % of one or a plurality of components D and 0.001 to 4 wt % of component A relative in each case to 100 wt % in dry weight of component L.

19. The method as claimed in claim 17, wherein component A is a mixture of caprolactam and oligomers of caprolactam, wherein the mixture has a number average chain length of more than 1 to a maximum of 10.

20. The method for producing lignocellulose materials as claimed in claim 17, wherein component A is caprolactam.

21. The method for producing lignocellulose materials as claimed in claim 17, wherein component B comprises a mixture of 4,4?-diphenylmethane diisocyanate and multicore diphenylmethane diisocyanate.

22. The method for producing lignocellulose materials as claimed in claim 17, wherein component B comprises polymeric diphenylmethane diisocyanate with an average functionality of more than two to a maximum of three.

23. The method for producing lignocellulose materials as claimed in claim 17, wherein 0.1 to 1 wt % of caprolactam relative to 100 wt % in dry weight of component L is used as component A.

24. The method for producing lignocellulose materials as claimed in claim 17, wherein 0.1 to 1 wt % of a mixture of caprolactam and oligomers of caprolactam relative to 100 wt % in dry weight of component L is used as component A.

25. The method as claimed in claim 17, wherein component A is used in an aqueous solution with a concentration of at least 25 wt % relative to the total weight of the solution.

26. The method for producing lignocellulose materials as claimed in claim 17, wherein component A is used as a solution in a polyol or a mixture of polyols or a mixture of polyol(s) and water.

27. The method for producing lignocellulose materials as claimed in claim 26, wherein the concentration of component A is at least 25 wt % relative to the total weight of the solution.

28. The method for producing lignocellulose materials as claimed in claim 17, wherein the heating in method step (IV) is carried out thermally or by means of an electrical high-frequency field or a combination of the two.

29. The method for producing lignocellulose materials as claimed in claim 17, wherein the lignocellulose materials are MDF (medium-density fiberboard), HDF (high-density fiberboard), PB (particle board), OSB (oriented strand board) or WFI (wood fiber insulation board).

30. Lignocellulose materials obtainable from the method as claimed in claim 17.

31. The lignocellulose materials as claimed in claim 30, with a transverse tensile strength as claimed in DIN EN ISO 319 of 0.1 N/mm.sup.2 to 1 N/mm.sup.2.

32. Furniture construction, housing construction, interior design and/or exhibition construction which comprises utilizing the :lignocellulose materials as claimed in claim 30.

Description

EXAMPLES

[0125] Materials and equipment

[0126] The wood chips used (component L) had a water content of 2-5 wt % relative to the dry weight of the chips. B/C chip mixtures were used for producing particle boards (weight ratio B:C=60:40, wherein the B fraction had a chip size of 0.5-2 mm and the C fraction a chip size of 2-4 mm. As a binder (component B), Lupranat® M 20 R from BASF SE (a polymeric MDI with a functionality of approx. 2.7) was used. A mixer was used that was equipped with a two-component nozzle operated with compressed air at a pressure of a maximum of 4 bar. As a prepress, a pneumatic piston press was used in which the scattered mat was compressed in a metal frame with the dimensions 30 cm×30 cm. Hot pressing was carried out according to example 2.

Example 1 (Cold Tack, Push-Off Test)

[0127] Batch 1-1: 5535 g of chips (moisture 2.5 wt. %, equivalent to 5400 g of chips abs. dr.) were placed in the mixer and sprayed during mixing with 216 g (4 wt % abs. dr.) of Lupranat® M 20 R. After this, the mixture was sprayed with 400 g of water.

[0128] Batch 1-2: 5535 g of chips (moisture 2.5 wt %) were placed in the mixer and sprayed during mixing with 108 g of 50 wt % aqueous caprolactam solution (1 wt % abs. dr.). After this, the mixture was sprayed with 346 g of water so that the total amount of water in the caprolactam solution with water was 400 g in this case as well. Finally, the mixture was sprayed with 216 g Lupranat® M 20 R (4 wt % abs. dr.).

[0129] Measurement of Breaking Length (as a Measure of Cold Tack):

[0130] A portion of the mixture (150 g) of batches 1-1 to 1-2 was poured into a mold to a height of 50 mm. The press ram was placed on top, and compression was carried out in the laboratory press with a specific pressure of 1 N/mm.sup.2 for 20 sec. The prepressed board was removed from the mold and placed on the feeding apparatus. After this, the mat was slid at a constant feed rate of 15 cm/min over the table edge until the mat broke off under the force of gravity. Using a ruler with accompanying movement, the length of the protruding mat until the point of breakage was measured (“breaking length”). This operation was then repeated twice, with respective pressing times of 80 sec and 160 sec.

[0131] The results are shown in Table 1,

TABLE-US-00001 TABLE 1 Batch Component (A) Pressing time Breaking length no. [wt % abs. dr.] prepress [sec.] [cm] 1-1 — 20 5.5 1-1 — 80 7.5 1-1 — 160 8 1-21 Caprolactam [1] 20 7.5 1-21 Caprolactam [1] 80 9 1-21 Caprolactam [1] 160 10

[0132] Table 1 shows the improvement in breaking length (cold tack) with the same pressing time using caprolactam as component A in contrast to precompressed boards without component A.

Example 2 (Pressing Time in the Hot Press)

[0133] Batch 2-1: 5654 g of chips (moisture 4.7wt. %, equivalent to 5400 g of chips abs. dr.) were placed in the mixer and sprayed during mixing with 300 g of water. After this, the mixture was sprayed with 216 g (4 wt % abs. dr.) of Lupranat® M 20 R.

[0134] Batch 2-2: 5654 g of chips (moisture 4.7 wt %) were placed in the mixer and sprayed during mixing with 214 g of water. After this, the mixture was sprayed with 108 g of 20 wt % aqueous caprolactam solution (1 wt % abs. dr.) so that the total amount of water in the caprolactam solution with water was 300 g in this case as well. Finally, the mixture was sprayed with 216 g of

[0135] Lupranat® M 20 R (4 wt % abs. dr.).

[0136] Batch 2-3: 5654 g of chips (moisture 4.7 wt %) were placed in the mixer and sprayed during mixing with 216 g of 25 wt % aqueous caprolactam solution (1 wt % abs. dr.). After this, the mixture was sprayed with 138 g of water so that the total amount of water in the caprolactam solution with water was 300 g in this case as well. Finally, the mixture was sprayed with 216 g of Lupranat® M 20 R (4 wt % abs. dr.).

[0137] Production of particle boards and determination of transverse tensile strengths:

[0138] After removal from the mixer, 1100 g of the mixture of batches 2-1 to 2-3 was evenly scattered in a mold measuring 30×30 cm.sup.2 and precompressed at room temperature with a specific pressure of 1 N/mm.sup.2 for 30 sec. The precompressed mat obtained was pressed using wax separating paper at 210° C. for the pressing times of the corresponding batches shown in Table 4. The pressing force was 4 N/mm.sup.2 for 2/3 of the pressing time, then 2 N/mm.sup.2 for 1/6 of the pressing time, and finally 1 N/mm.sup.2 for ⅙ of the pressing time. The board thickness was adjusted using 16 mm spacer strips composed of metal. After pressing, the finished particle board was removed from the hot press and allowed to stand in storage for one day. Measurement of the transverse tensile strengths was carried out according to DIN EN 319 on at least 8 test pieces per particle board. Minimum pressing time is defined as the pressing time with which a stable board with a transverse tensile strength of at least 0.4 N/mm.sup.2 is obtained.

[0139] The results are summarized in Table 2.

TABLE-US-00002 TABLE 2 Batch Minimum No. Component (A) pressing time [s] 4-1 — 104 4-2 Caprolactam 0.4% abs. dr. 88 4-3 Caprolactam 1.0% abs. dr. 72

[0140] Table 2 shows the improvement in minimum pressing time in use of caprolactam as component A according to the invention.