Stock material or miscellaneous articles – Composite – Of carbohydrate
Patent
1986-01-21
1988-08-02
Gibson, Sharon A.
Stock material or miscellaneous articles
Composite
Of carbohydrate
428 15, 428106, 428113, 428325, 428452, 428453, 428921, 106 1812, B32B 2104, B32B 2106
Patent
active
047613424
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a fibre board having high strength as well as high water and flame resistance, a method for making said board, and a new type of an inorganic binder for bonding wood fibres.
In the manufacture of fibre boards, e.g. particle boards, certain demands are placed on the binder used. Except that it should yield a board of high strength and water resistance, it should be inexpensive and non-toxic. If the binder also contributes to making the board more flame-resistant, this is of course a substantial advantage.
As binders for fibre boards, use has hitherto been made primarily of organic resins, especially urea-formaldehyde resins, which are advantageous in many respects, for instance by having high reactivity, by being inexpensive and yielding boards of high strength and acceptable water resistance. However, they suffer from a considerable drawback because, even after setting, they emit formaldehyde, which is regarded as a relatively toxic substance, for a long period of time. Different methods are used for reducing the emission of formaldehyde, but this problem has not yet been solved. Therefore, the usefulness of formaldehyde-bonded particle boards e.g. for internal walls in houses, is being increasingly questioned.
Further, the organic binders yield boards with relatively poor flame resistance. In order primarily to improve the flame resistance, different inorganic binders have been tried in the manufacture of fibre boards.
In most cases, the inorganic binders have been based on water glass, i.e. a solution of alkali silicate in water. Water glass has in itself too low a dry content and too low a reactivity to be suitable in this connection. By adding inorganic fillers and setting agents of different kinds, it is possible to solve these problems to a certain extent. By using suitable combinations of water glass-setting agent-filler, boards with relatively good mechanical properties have been obtained (see e.g. GB patent specification No. 557,371 and EP patent specification No. 68,856).
The use of a water glass binder in fibre boards generally results in a considerable improvement of the flame resistance as compared with conventional resin-bonded boards. However, the major problem in water glass-bonded boards is the resistance to water. Water glass glue when set has very poor water resistance, and despite substantial efforts to find hydrophobing agents for the systems, this problem has not yet been solved. For this reason, water glass-bonded boards have not yet become useful in actual practice.
The present invention comprises a fibre board manufactured with a new type of binder composition. The use of the new binder, which is of an inorganic nature, in the manufacture of a fibre board yields a board combining high strength and acceptable water resistance with high flame resistance. Since the binder does not contain any organic resins of any type, the problems related to the emission of formaldehyde and other organic setting products will also be overcome.
The fibre board according to the present invention consists of a lignin-containing fibre material, a binder derived from a binder composition and, optionally, further components, such as fillers and hydrophobing agents.
The lignin-containing fibre material may consist e.g. of wood fibres in general, wood chips and so-called wafers. Other less common waste products, such as rice hulls and straw, can also be used.
The binder composition used for manufacturing the fibre board consists of a mixture of the following components:
(a) an alkali silicate solution
(b) sulphur and/or an inorganic sulphur compound
(c) a calcium and/or magnesium compound.
Preferably, the alkali silicate solution is a solution of sodium silicate (Na-water glass) or potassium silicate (K-water glass) in water. The preferred dry content range is 40-60% and the most preferred silicate is Na-water glass in which the ratio of SiO.sub.2 to Na.sub.2 O is in the range of 3.5-1.4.
The sulphur component preferably is elementary sulphur, sodium sulphide or sodium sulph
REFERENCES:
patent: 2223240 (1940-11-01), Hughes
patent: 2552597 (1951-05-01), Smith
patent: 3377229 (1968-04-01), Bryan
patent: 4263048 (1981-04-01), Hacker
patent: 4582755 (1986-04-01), Dietrich
Bjorhaag Georg
Embring Goran
Stahl Karl-Gunnar
Gibson Sharon A.
Nova Scand Utveckling AB
LandOfFree
Fibre board, a method for making it, and a binder composition does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fibre board, a method for making it, and a binder composition, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fibre board, a method for making it, and a binder composition will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-711436