Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
1999-04-12
2001-04-24
Cooney, Jr., John M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C521S155000, C521S170000, C521S174000
Reexamination Certificate
active
06221929
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a rigid foamed polyurethane-forming composition, a foamed polyurethane molding and a model. More particularly, the present invention relates to a rigid foamed polyurethane molding suitable for cutting and a model obtained by cutting the same foam molding.
BACKGROUND ART
Such models as mock-ups or full-sized models of cars or household electronic products and master models or master mold forms are built of rigid foamed polyurethane blocks by cutting. Rigid foamed polyurethane blocks as modeling stock are made by such processes as one in which a basic material composition is mixed with hollow microspheres as weight-reducing agent and is allowed to cure in a mold and another one in which an inert gas is dispersed in the basic material composition by an agitator to reduce weight and the composition is allowed to cure in a mold in that state. The latter is known as a mechanical frothing method. Those techniques are disclosed in U.S. Pat. Nos. 4,916,173 and 5,401,785.
The problem with the prior art rigid foamed polyurethanes is, however, that much dust tends to rise in cutting work, contaminating the working environment. That is especially the case with polyurethane moldings in which inorganic fillers such as talc and calcium carbonate are used in large quantities to improve the dimensional stability and those of which the density is lowered for better manual workability. And demands have been voiced for an improvement in that aspect.
It is an object of the present invention to provide a rigid foamed polyurethane which is largely free from dust-scattering in cutting work.
It is another object of the present invention to provide a composition from which such a low dust-scattering foamed polyurethane can be obtained.
It is still another object of the present invention to provide a model made of such a low dust-scattering foamed polyurethane.
DISCLOSURE OF INVENTION
The objects of the present invention are attained by the following [1] to [4].
[1] A rigid foamed polyurethane-forming composition, which comprises:
a polyol with a hydroxyl value of 200 to 700 (a); an organic polyisocyanate (b); a filler comprising an inorganic powder and/or a hollow microsphere (c); and a dehydrating agent (d);
wherein said composition further contains 3 to 30 percent, based on the total weight of the composition, of a (poly) oxyalkylene compound (e) expressed by the general formula
Z[(AO)
m
X]
n
in which “A” represents an alkylene group with two to four carbon atoms; “X” is a hydrocarbyl group or an acyl group; “m” is a value of one to one hundred; “n” is an integer of one to six; and “Z” is a residue produced by removing the active hydrogen atoms from a compound containing n active hydrogen atoms, in which at least one of Z and n X's has 5 to 20 carbon atoms and “X” may be either the same or different in case “n” is two or more.
[2] A rigid foamed polyurethane molding obtainable by curing a composition comprising a polyol with a hydroxyl value of 200 to 700 (a); an organic polyisocyanate (b); a filler comprising an inorganic powder and/or a hollow microsphere (c); and a dehydrating agent (d).
The aforesaid composition further contains 3 to 30 percent, based on the total weight of the composition, of the above-mentioned (poly) oxyalkylene compound (e) and the above-mentioned curing is effected under finely dispersed bubble containing conditions.
[3] A method of making a rigid foamed polyurethane molding, which comprises curing a composition by a mechanical frothing method, said composition comprising: a polyol with a hydroxyl value of 200 to 700 (a); an organic polyisocyanate (b); a filler comprising an inorganic powder and/or a hollow microsphere (c); and a dehydrating agent (d);
wherein said composition further containing 3 to 30 percent, based on the total weight of the composition, of the above-mentioned (poly) oxyalkylene compound (e).
[4] A model obtainable by cutting the molding described in above-mentioned [2].
The aforesaid (poly) oxyalkylene compound (e) acts as a dust-scattering reducer in the present invention.
BEST MODE FOR CARRYING OUT INVENTION
[Concrete Examples of Polyol (a)]
Among the polyols with a hydroxyl value of 200 to 700 (a) suitable for use in the present invention are polyether polyol, polyester polyol and other polyols.
As examples of the polyether polyol, the following compounds are named: those obtainable by addition of alkylene oxide to compounds which have at least two and preferably three to eight active hydrogen atoms such as polyhydric alcohol, polyhydric phenol, amines, polycarboxylic acid, phosphoric acid, and mixtures of two or more of them.
The polyhydric alcohols include the following compounds: dihydric to octahydric ones such as ethylene glycol, propylene glycol, glycerol, trimethylolpropane, pentaerythritol, methylglucoside, diglycerol, sorbitol and sucrose.
Among the polyhydric phenols are hydroquinone, bisphenol A and phenol-formaldehyde condensation products.
The following may be cited as amines: triethanol amine, triisopropanol amine, ethylene diamine, diethylene triamine, toluene diamine and diphenyl methane diamine.
As the polycarboxylic acids may be cited the following: aliphatic dicarboxylic acids (anhydride) such as adipic acid, sebacic acid and maleic anhydride; and aromatic polycarboxylic acids such as phthalic anhydride, terephthalic acid, trimellitic acid and pyromellitic acid.
Among the alkylene oxides to add to the compounds containing active hydrogen atoms are ethylene oxide (EO), propylene oxide (PO), 1, 2-, 2, 3-, 1, 4- or 2, 3-butylene oxide, styrene oxide, and combinations of these compounds, which may be added blockwise and/or randomwise. Among those, preferred are PO and the combination of EO and PO.
As the polyester polyols, the following compounds may be named: polyester polyols condensated from polycarboxylic acids and polyols, and lactone polyester polyols produced by lactone ring-opening polymerization.
The above-mentioned polycarboxylic acids include those named above as the raw materials for polyether polyols. Preferred are adipic acid, phthalic anhydride and terephthalic acid.
Among the aforesaid polyols are polyhydric alcohols cited above as the raw materials for polyether polyols and their alkylene oxide low-mol adducts (usually, one to three mols). Preferred are 1,4-butanediol, ethylene glycol, and diethylene glycol.
The concrete examples of the condensated polyester polyols include poly (1,4-butanediol) adipate, poly (1,4-butanediol) terephthalate and poly (diethylene glycol) terephthalate.
Lactones used in the lactrone polyester polyols include &egr;-caprolactone and &dgr;-valerolactone. Preferred is &egr;-caprolactone. Among the concrete examples of lactone polyester polyols is poly &egr;-caprolactone polyol.
The other polyols include such compounds as polyether polyols graft-modified with the homopolymer or copolymer of such vinyl compounds as acrylonitrile, styrene and methyl methacrylate, polybutadiene polyols and hydroxyl group-contained vinyl polymers (acrylic polyols such as ones disclosed in examined Japanese patent application No. 58-57413).
The hydroxyl value of the polyols (a) is generally between 200 and 700, and preferably between 250 and 600. With a hydroxyl value less than 200, the resulting polyurethane moldings are insufficient in heat resistance and strength for use as modeling stock. In case where a hydroxyl value is more than 700, the moldings are too rigid and brittle, and what is more, those moldings tend to scorch because of the heat of reaction between polyol (a) and polyisocyanate (b).
Of the polyols (a), the preferable are alkylene oxide adducts of polyhydric alcohol. Especially preferred are polypropylene oxide adducts of gylcerol, trimethylolpropane, triethanol amine, pentaerythritol, sorbitol and sucrose.
Other active hydrogen-contained compounds than those polyols (a) may be used in combination with those polyols (a) so long as the properties required in t
Ryugo Jiro
Sasatani Yuichi
Cooney Jr. John M.
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Sanyo Chemical Industries Ltd.
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