MXPA94005910A - Hardening aglomerantes term - Google Patents

Abstract

The present invention relates to a process for the preparation of materials from the group of agglomerate or particle boards, textile fleece, heat and sound absorption plates, by mixing a binder with products containing cellulose, introducing the mixture into a mold and treated at a temperature in the range of 150-210 ° C, and at a pressure in the range from 0.1 to 4 MPa, characterized in that the binder contains a tannin from the group of procyanidins and / or prodelfinidines, particularly tannin from pecan nut and / or pine bark as well as hexamethylenetetramine

Description

THERMAL HARDENING AGGLOMERANTS INVENTORS: ANTONIO PIZZI, Italian, ILLI ROLL German and BERTHOLD DOMBO, German domiciled in Maison 7 Rue de Champs St. Michelle, F-88000 Epinal / France; Südstrasse 15, D-48337 Al tenberge / Germany and in Ferdinand- Strahl-Str. 46 D-41061 Dnchengladbach / Germany, all assign their rights to RUTGERSWERKE AKTIENGESEL SCHAFT duly organized and incorporated company in accordance with the Laws of Germany, domiciled at Mainzer-Landstrasse 217 - 60326 Frankf urt / Main, Federal Republic of Germany, by the invention that is described right away.

SUMMARY OF THE INVENTION There are presented binders that harden with the application of heat for products that? They contain cellulose, which contain tannin and a product, which, with heat application, releases formaldehyde. The products made with them show a good resistance and a low absorption coefficient after storage in water. The invention relates to binders, which harden with the application of heat, which can be used with wood and other products containing cellulose and which are specially adapted for the manufacture of wood products, such as for example agglomerated wood boards. In relation to the search for natural raw materials and especially renewable for the manufacture of binders for wood products is also known the use of tannin < J. Ma romo1. SCI.-Chem. A 16 (7), 1243-1250 (1981). Despite its good availability, its use, however, has not been developed, because the tensile strength, especially after storage in water of wood products agglomerated with tannin is not sat isf ctori. Accordingly, it is an object of the present invention to provide a binder based on tannin, with which wood products with improved mechanical properties can be manufactured. The solution of this object is effected by means of tangent-containing binders according to claims 1 to 6, respectively by means of the use of binders for the manufacture of wood products based on products containing cellulose in accordance with claim 7 as well as by means of the method for the manufacture of wood products, such as for example wooden boards-bellowed wood, in accordance with the ri ions 8 to LO. It was cinched, that the tan. no, it contains units of the general structure wherein P is hydrogen or a hydrolyzole group, and the lyseryl bonds on the oxygen radicals are linked either with hydrogen or with links to other molecular groups such as, for example, radicals of a-radicals or radicals of compounds? It goes 1 e * - »iferente or identical rhenol groups hidr phenol LI.os, which show a binding capacity sob? 1 i in relation to uMus tamnos, when an element that liquefied formaldehyde is added together with a high blended content for product containing cellulose. The resistance to the trat L n t s and -i.11 an / to a value, which is found, for example, at the level of wood products agglomerated with phenol resin. The reduction of the transverse tensile strength after storage in water is significantly reduced and the swelling coefficient in boiling water is also lowered. Another advantage of the present invention is that these tannins can be used without additional handling, as in the case of the other t and nos. The corresponding tannins are those belonging to the group of pracianidines and pradelf inidina, especially tannin from pine bark or pecan. Mixtures of these tannins with, for example, mimosa tannin or quebracho tannin in a ratio of 2: 5 to 5s2, although they have an elongated hardening time, can be used. These tannins are products readily available in commerce and have been used to date essentially as tanning agents. The qualities found in commerce are sufficient for use in the product according to the present invention. The products that release in formaldehyde heat conditions are, for example, paraformaldehyde, trio: <Anus and especially hexameter and lens ina (Hexa). According to the present invention, the binders that harden with application of heat are, in the simplest case, a mixture of tani not containing structural units of formula and a product that releases form in hot conditions, where the proportion of product that releases formally due, especi a 1 mind he: amet i 3 e-ntet rami na nLuenira between 3.0V. and Y < by weight, in relation to the t aiu no. Also within the scope of the present invention is a binding agent separate from the special types of taro and from an element that releases shape in the heat-containing condition up to 5 < "> * / 4 in e-iD of a Novo! ti- or even up to 20 * /. in weight of a rnmue->, or minimally in fl uenced 1 as for the wool f, to J i na, ', 4' '- I-ri isociana o-i item 1 et nici, d i i ac lac > dei i so forono- tolun] - o he; i the i leño, or Well di isot? anato-d? fe-n? 1 methane frlDl) 1, so in practical use the di- or pol isocyanate in parallel to the dry mixture of tannin used in accordance with the present invention and the product that releases formaldehyde under heat conditions is applied to the cellulose-containing material, before the compression of said material into the corresponding products.The corresponding cellulose-containing products are, for example, wood chips, cellulose-containing yarns as , for example, cotton, linen or straw, from which agglomerated wood boards, textile fleeces, or boards for thermal or acoustic insulation are made. The manufacture of the products is carried out in that the binder according to the present invention is mixed with cellulose-containing products, this mixture is brought to a form and at a temperature above the decomposition temperature of the product releasing formaldehyde and lower at the decomposition temperature of the tannin, and it is preferred that it hardens at a temperature comprised between 150 and 210 ° C under pressure. The pressure consists, depending on the material used and the desired density, of between 0.1 and 4 MPa / mm2. For example, also the manufacture of three-layer chipboard is possible with a pressure of 2 to 3.5 MPa / mm2.

The amount of binder is, depending on the product and the desired strength, between 4 and 20% by weight, relative to the cellulose-containing product. The binder can be in the form of a ready-made mixture, or in the form of a solution of components in water, alcohol or a mixture of alcohol and water. The corresponding solutions can be stored at room temperature for several weeks without a significant increase in viscosity being observed. In the case of aqueous solutions, it is advisable only to add a fungicide to prevent the appearance of mold. The following examples show the binder according to the present invention in its use for the manufacture of agglomerated wood boards. EXAMPLES The wood chips were sprayed with an aqueous-alcoholic solution, which contains 11% by weight of binder in relation to the weight of the wood and dried. Later said chips were formed by using a known technique (2.5 N / mm2; 195 ° C) in 400 dimension tables; 350 x 12 mm, pressed and hardened. The density, tensile strength of tables a) was determined in dry condition and b) after storage in water (2 hours in boiling water, followed by 16 hours at a drying temperature of 105 ° C), as well as the increase in thickness after 2 hours storage in boiling water in various mixing ratios of the binder components, amount of binder, and pressing time. Examples 1-5 In the case of Example 1, the proportion of hexamethine lens varies from 7.5 to 5.5% of the binder. Correspondingly, the proportion of pecan nut tannin from 92.5 to 94.5% also varies. At. Example 2, the hexamethine lenspart, in relation to the tannin, is 6.4%, that is, the pecan nut tannin portion is 93.6%. What varies is the pressing time. Example 3 shows the values for a three layer table with 6.4% hexamethine lens in the binder, a binder content of 10% in the central layer and 12% in the outer layers. Examples 4 and 5 show the values analogous to those of Examples 1 and 2 by the use of mimosa tannin. The following tables show the values obtained: T B L A S Example 1 Example 4 (Comparison) Hexameti lentetramine 7.5% 6.4% 5.5% 7.5% 6.5% Press Time (sec / mm) 17.5 17.5 17.5 17.5 17.5 Density (kg / mr ») 729 730 736 731 711 Transverse tensile strength, dry (MPa) 0.82 0.81 0.79 0.45 0.4: Transverse tensile strength after storage in water (MPa)? 2b 0.27 0.26 0.09 .07 Inflation (%) 25.0:? 32.1;?. S Emission of HCHO (mg / lOOg, W I) 1.71 1.45 0.84 2.01 1.87 Example 2 Example 5 (Comparison) (6.4% Hexa (6.5% Hexa) Pressing time (sec / mm) 17.5 12.5 8.5 30.0 17.5 12.5 Density (kg / mf) 730 738 733 714 731 722 Transverse tensile strength, dry (MPa) 0.81 0.75 0.67 0.5 0.45 0.41 Transverse tensile strength after storage in water (MPa) 0.27 0.19 0.17 0.13 0.09 0.03 Inflation (%) 23.9 22.4 20.9 29.7 32.1 36.7 Emission of HCHO (mg / lOOg; WKI) 1.45 1.32 1.1 1.64 2.01 1.28 Example 3 Press time (sec / mm) 12.5 Binder (%) Core / Coating 10/12 Chip moisture after application of binder (%) Core / Coating 28/26 Density (kg / m3) 723 Transverse tensile strength in dry condition (MPa) 0.83 Transverse tensile strength after storage in water (MPa) 0.27 Swelling (%> 22.1 Emission of HCHO (g / lOOg? WI) 1.4 Example 6 In accordance with the general description of the Examples (Press time 15 s / mm to 190ßC, 2.5 N / mm =) single-ply chipboards were manufactured and tested. Binder: Pine Bark Tannin (37% aqueous solution) 337 parts by weight Hexamethyletramine (40% aqueous solution) 19.3 parts by weight Zinc Acetate (25% aqueous solution) 19.3 parts by weight Water 10 parts by weight Resul ates: Density (kg / cmO: 708 Tensile strength, dry (MPa) 0.80 Tensile strength after storage in water (MPa): 0.23 Emission of HCH0 (mg / 100 g): 0.1 Example 7 In accordance with the general description of the Examples (pressing time 15 s / mm to 190ßC; 2.5 N / mm2) three-ply bonded boards were manufactured and tested. Binding agent Central layer External layers Pine bark tannin (37% aqueous solution) 327 327 parts by weight Hexamethine lens (40% aqueous solution) 19.5 19.5 parts by weight Zinc acetate (25% aqueous solution) 24.0 19.5 parts by weight Water 12 parts by weight Results:

Claims (9)

1. Density (kg / m3) 723 Tensile strength, dry (MPa) .80 Tensile resistance after storage in water (MPa): 0.29 HCHO emission (mg / 100 g): 0.16 NOVELTY OF THE INVENTION Having described the present invention, it is considered a novelty and, therefore, what is claimed in property is contained in the following CLAIMS 1. A thermal hardening binder for products containing tannin-based cellulose, characterized in that it contains tannin of pecan nut and an element that léra in condition of heat form ldehyde, which contains tannin units of the general structure where R is hydrogen or a hydroxyl group, and the free bonds with the oxygen radicals are linked with either hydrogen and / or other molecular groups.
2. 2. The binder according to claim 1, characterized in that the tannin used is pecan nut tannin or pine bark tannin.
3. 3. The binder according to claim 1 or 2, characterized in that the product that releases formaldehyde under heat condition is hexa et i leptetramine.
4. 4. The binder according to claim 3, characterized in that the content of hexamethine lens is from 3.0 to 9% by weight, in relation to tannin.
5. 5. The binder according to claims 1 and 2, characterized in that it contains up to 50% by weight of Navalak.
6. The binder according to claims 1 and 2, characterized in that it contains up to 20% by weight of at least one dysfunctional isacyanate compound.
7. 7. The use of the binder according to claims 1 to 6 for the manufacture of products based on cellulose-containing materials.
8. 8. The process for the manufacture of products, characterized in that a binder according to the rei indications 1 to 6 is mixed with a cellulose-containing material, this mixture is formed and brought to a temperature comprised between 150 and 210 ° C under a pressure located between 0.1 and 4 MPa / m2.
9. 9. The procedure according to claim 8, characterized in that the binder in powder form is mixed with wood chips. JO. The process according to claim 8, characterized in that the binder in the form of solution is roela on the wood chips. In testimony of which, I have signed the previous description and novelty of the appointment as attorney-in-fact of RUTGERSWERKE AKTIENGESELLSCHAFT, in Mexico City, Federal District, today, August 3, 1994. p.p. of RUTGERSWERKE AKTIENGESEL SCHAFT EDUARDO CORREA E.