Fiberplates made of polyamines or polyamine-containing...

Details Fiberplates made of polyamines or polyamine-containing... Fiberplates made of polyamines or polyamine-containing...

2001-12-31

2003-09-23

Truong, Duc (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

From aldehyde or derivative thereof as reactant

C528S254000, C528S256000, C524S501000, C524S509000, C428S502000, C428S505000

Reexamination Certificate

active

06624284

ABSTRACT:

This application is a 371 of PCT/EP00/05858 filed Jun. 23, 2000.
The present invention relates to a process for producing fiberboard panels by
I. gluing cellulosic fibers with an aqueous glue solution comprising
a) for a glue solution (a), an aliphatic polyamine having at least 3 groups selected from the group consisting of primary and secondary amino groups, having a weight average molar weight of from 600 to 1000000 g/mol, and being substantially free from other functional groups apart from tertiary amino groups (polyamine P); or
b) for a glue solution (b), a mixture of a polyamine P and an amino resin (b) synthesized from
b1) formaldehyde;
b2) a compound (b2) selected from the group consisting of urea and melamine, the ratio of the amino groups of compound (b2) to formaldehyde being from 0.4:1 to 3:1;
b3) and, if desired, up to 0.2 mol per mole formaldehyde of another compound, (b3), capable of reacting with formaldehyde in a polycondensation reaction;
b4) and, if desired, up to 0.2 mol per mole amino groups of compound (b2) of another compound, (b4), capable of reacting with amino groups in a polycondensation reaction; or
c) for a glue solution (c), an amino resin (c) synthesized from
c1) formaldehyde;
c2) a compound (c2) selected from the group consisting of urea and melamine, the ratio of the amino groups of compound (c2) to formaldehyde being from 0.3:1 to 3.0:1;
c3) a polyamine P, the molar ratio of the sum of primary, secondary, and tertiary amino groups of polyamine P to the sum of primary amino groups of compound (c2) being from 0.0005:1 to 2:1;
c4) and, if desired, up to 0.2 mol per mole formaldehyde of another compound, (c4), capable of reacting with formaldehyde in a polycuadensation reaction; and
c5) if desired, up to 0.2 mol per mole amino groups of compound (c2) of another compound, (c5), capable of reacting with amino groups in a polycondensation reaction;
and adjusting the moisture content of the cellulosic fibers and/or the water content of the glue such that the moisture content of the glued cellulosic fibers is not more than 150%; and
II. compressing the glued cellulosic fibers produced in step (I) at elevated temperature to fiberboard panels.
The invention further relates to fiberboard panels produced by this process and to the glue solution (c).
The production of fiberboard panels is common knowledge and is described, for example, in the monograph entitled “MDF—Mitteldichte Faserplatten” by Hans-Joachim Deppe, Kurt Ernst, 1996, DRW-Verlag Weinbrenner GmbH & Co., 70771 Leinfelden-Echterdingen (DE). Fiberboard panels may be produced, for example, by gluing cellulosic fibers with amino resins and then compressing them at elevated temperature. A disadvantage of the fiberboard panels produced in this way is that relatively large quantities of glue are required in order to produce panels having good mechanical properties, particularly a good transverse tensile strength. Moreover, in the predominant number of plants, the cellulosic fibers used must be predried after gluing, since the fibers glued with the conventional binders must have a moisture content of only up to 12% if problems are to be avoided during the production of the panels.
Apart from the fact that they are both woodbase materials, chipboard and fiberboard have little in common. This relates first to the performance properties. The aforementioned monograph by Deppe/Ernst refers explicitly to this, for example, concerning comparison of the performance properties of the two materials (cf. paragraph 1 of section 6.3 and paragraph 1 of chapter 7, “IMDF and chipboard panels differ in performance, in some cases very considerably”). From the aforementioned monograph it is also known that the manufacturing technology of each is also different and that the raw wood material used has different properties and is differently prepared. For example, at the beginning of section 4.1 of the monograph, there is the following note: “In terms of the preparation of the raw material, critical differences exist between chipboard and MDF technologies”. And at the beginning of section 4.2 it goes on to say: “Fiber material requires, for its drying, technical equipment which differs fundamentally from the types which are common in the chipboard industry”. It is consequently no surprise to the skilled worker that binders for the production of chipboard panels and MDF are not suitable in the same way. Whereas resins comprising polyethyleneimine as sole binder give high-grade MDF (cf. examples 1 to 6) it is virtually impossible to product chipboard panels from the same resin (cf. comparative example 3). The conclusion the skilled worker draws from this is that experience gained in the production and properties of chipboard panels cannot be transferred to MDF.
For the sake of comprehensiveness it should nevertheless be mentioned that DE-A-4308089 discloses producing chipboard panels with a binder comprising an aqueous solution of a polyamine, from 0.01 to 0.25 mol sugar per mole of amino groups, and from 0.01 to 0.25 mol, per mole amino groups, of dicarboxylic acid derivatives, aldehydes or epoxides.
U.S. Pat. No. 3,642,671 proposes producing chipboard panels by resinating wooden chips with a resin comprising polyethyleneimine and dextrose or other dextroselike compounds and compressing them to chipboard panels under elevated temperature and pressure.
Journal of Applied Polymer Science 49 (1993) 229-245 describes how chipboard panels bound with modified urea-formaldehyde resins are found more resistant and more stable in a hot, moist environment than those produced using customary amino resins. Proposed modifiers are low molecular mass polyamines or their hydrochlorides or polyalkylene oxide diamines.
USSR patents 501890, 612819, 844273 and der JP-A S57-95399 disclose MDF produced by the wet process. In this process an aqueous suspension of cellulosic fibers, a polyethyleneimine, and other auxiliaries, with a water fraction of more than 95%, is poured out and predried to mats having water contents of more than 60% (corresponding to fiber moisture contents of 150% based on bone dry fiber). These mats are subsequently compressed to hardboard panels.
The furniture industry has a particular requirement for fiberboard panels which
are highly compacted, so that they have good mechanical properties,
are from about 6 to 40 mm thick, so that they can be used to produce furniture side pieces or doors, and
have a smooth surface on both sides. Panels of this kind are referred to as S2S (smooth two sides) panels (cf. Ullmann's Encyclopedia of Industrial Chemistry, 1996 VCH Verlagsgesellschaft, Vol. A 28, section 2.3.2.1, page 336)
For economic reasons, fiberboard panels having this profile of properties are not produced by the wet process. That process can only be used economically to produce panels of high density with a thickness of up to 5 mm (cf. Ullmann's Encyclopedia of Industrial Chemistry, 1996 VCH Verlagsgesellschaft, Vol. A 28, section 2.3.2.2, page 337, column 1, paragraph 1). The reason for this is that with this process it is not possible using economic pressing conditions to achieve adequate compaction and curing of the middle of the panel. Moreover, the panels produced by the wet process have a rough surface on one side. This is a consequence of the production process: to remove the higher water fraction it is necessary when compressing the fiber molding for one press tool to have a screen structure. The pattern of this screen structure is embossed on one of the sides of the fiber panel. Panels of this kind are known as S1S (smooth one side) panels. This uneven surface is often troublesome in the course of further processing, when coating with decorative paper, for example.
A further disadvantage of the wet process is that it produces large amounts of contaminated wastewater.
It is an object of the present invention to provide fiberboard panels which do not have the abovementioned disadvantages and which are characterized in particular by the following properties: a thickness of from 6 to 40 mm, a density of from

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