Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2000-03-31
2003-10-07
Sergent, Rabon (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S059000, C524S064000, C524S127000, C524S167000, C524S211000, C524S284000, C524S292000, C524S296000, C524S297000, C524S298000, C524S356000, C524S369000, C524S425000, C524S439000, C524S442000, C524S445000, C524S447000, C524S450000, C524S451000, C524S452000, C524S487000, C525S123000, C525S127000, C525S128000, C525S129000, C525S130000, C525S424000, C525S440030, C525S455000, C525S457000, C428S402000, C428S423100, C523S218000, C523S219000, C528S045000, C528S049000, C528S059000, C528S061000, C528S074500
Reexamination Certificate
active
06630534
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a polyurethane paste composition applied mainly onto vehicles. This invention relates in particular to a polyurethane paste composition which is endowed with excellent fluidity or a certain shape retainability at ordinary temperature and can be easily hardened (swollen and formed integral) upon heating. Furthermore, the composition is excellent in physical properties of its hardened product, such as adhesion strength, low-temperature flexibility, chemical resistance and mechanical strength.
BACKGROUND ART
As it is known, prior to finish coating, a sealing composition has been applied onto a joint between steel plates or an edge of a steel plate in an automobile body after electro-deposition coating to make that portion water- and air-tight and to improve rust prevention. Also, in order to improve rust resistance and chipping resistance, an undercoating composition has been applied onto a lower floor part, a foil house, a side sill etc. in the automobile body.
As the sealing or undercoating composition, {circle around (1)} so-called vinyl chloride-based plastisol composition prepared by plasticizing crystalline resin powder such as vinyl chloride resin, vinylidene chloride resin etc. with a phthalate-based plasticizer and then incorporating suitable fillers and other additives (e.g., JP-A 08-020697) is used in many cases because of its excellent rust prevention, easy formation of a thick film and low costs. Also, {circle around (2)} so-called one-pack blocked polyurethane composition prepared by blending blocked polyisocyanate with active hydrogen compounds such as polyamine, polyamide and polyol (e.g., JP-A 6-299065) is generally used when coating appearance and coating strength are regarded more important. As non-vinyl-chloride sealing composition, there is {circle around (3)} so-called acrylic resin-based plastisol composition comprising acrylic resin-based resin powder, a plasticizer, fillers and other additives (e.g., JP-A 10-231409).
However, the composition {circle around (1)} has the problem of low adhesion on a metal and an electro-deposited surface because of high crystallinity of vinyl chloride-based resin. Further, environmentally deteriorating substances such as Pb, Cr etc. are used as aging-preventing agents to stabilize a hardened product for a prolonged period of time. The composition {circle around (2)} should be stored at low temperature because of its poor storage stability. when it is attempted to achieve desired setting properties and mechanical strength, the prepolymer should be highly polymerized or the cohesive force between prepolymer molecules should be raised. By doing so, however, the viscosity is raised and use of a solvent, a plasticizer and a reactive diluent is inevitable, resulting in failing to achieve sufficient thixotropy thus permitting sagging to occur easily. {circle around (3)} has the problem of insufficient strength at ordinary temperature when the Tg of the resin is decreased in order to raise flexibility at low temperature.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a polyurethane paste composition which is a product excellent in workability in the form of sol having excellent paste fluidity at ordinary temperature and can be endowed with a certain shape retainability by addition of a shape-retaining agent. Another object is to provide a polyurethane paste composition which can be easily hardened by heating. An additional object is to provide a polyurethane paste composition excellent in adhesiveness, mechanical strength and low-temperature flexibility of its hardened product. A still other object is to provide a polyurethane paste composition which is excellent in storage stability in the state of a paste and highly safe for the environment.
That is, the present invention relates to a polyurethane paste composition comprising fine particles (A) consisting of polyurethane resin, a plasticizer (B) and fillers (C). Hereinafter, the present invention is described in detail.
The fine particles (A) in the present invention are composed of urethane resin and thus have a microphase-separated structure consisting of hard and soft segments unique to urethane resin. Accordingly, they are excellent in storage stability at ordinary temperature due to strong aggregation of hard segments. Moreover, their high strength can also be maintained after thermosetting. The plasticization thereof by a plasticizer is directed mainly to their soft segments, to make the Tg of a hardened product sufficiently low and to improve flexibility at low temperature.
Besides, the viscosity of the composition depends on interaction in the interface among the fine particles (A), the fillers (C) and the plasticizer (B) so that even if the prepolymer is highly polymerized or the cohesive force between prepolymer molecules is raised, physical properties of its hardened product, such as adhesion strength, chemical resistance and mechanical strength, can be improved while maintaining the rheologidal characteristics of the composition at ordinary temperature without raising the viscosity thereof.
The composition of the present invention is useful as a sealing or undercoating composition for automobiles and as a sealing material, putty and joint compounds in the fields of civil engineering and architecture. Further, when the product of the present invention is used as a sealing material for automobiles, this sealing material easily burns up for recycling, thus improving the recycling performance of the body.
DETAILED DESCRIPTION OF THE INVENTION
The method of producing the polyurethane resin according to the present invention is not restricted in particular, and known method can be used. The polyurethane resin is, for example, formed by reacting an isocyanate group-terminated urethane prepolymer (a) derived from an excess polyisocyanate (a1), a high-molecular weight diol (a2) having a number average molecular weight of 100 to 10,000 and, optionally, a low-molecular weight diol (a3) with an aliphatic diamine (b1) and a mono- or di-alkanolamine (b2) containing 2 to 4 carbon atoms in the hydroxyalkyl group or an aliphatic monoamine (b3).
The aforesaid polyisocyanates (a1) include:
{circle around (1)} aliphatic diisocyanates with 2 to 18 carbon atoms (except the carbons in the NCO group, similarly hereinafter), e.g., ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (hereinafter referred to as HDI), dodecamethylene diisocyanate, is 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethyl caproate, bis(2-isocyanatoethyl)fumarate, bis(2-isocyanatoethyl)carbonate, 2-isocyanatoethyl-2,6-diisocyanatohexanoate, and the like;
{circle around (2)} alicyclic diisocyanates with 4 to 15 carbon atoms, e.g., isophorone diisocyanate (hereinafter referred to as IPDI), dicyclohexylmethane-4,4′-diisocyanate (hereinafter referred to as hydrogenated MDI), cyclohexylene diisocyanate, methyl cyclohexylene diisocyanate (hereinafter referred to as hydrogenated TDI), bis(2-isocyanato ethyl)-4-cyclohexene, and the like;
{circle around (3)} aromatic polyisbcyanates with 6 to 14 carbon atoms, e.g.,
1,3-
and/or 1,4-phenylene diisocyanate, 2,4 -and/or 2,6-tolylene diisocyanate(hereinafter referred to as TDI), crude TDI, 2,4′-and/or 4,4′-diphenylmethane diisocyanate(hereinafter referred to as MDI), 4,4′-diisocyanato biphenyl, 3,3′-dimethyl-4,4′-diisocyanato biphenyl, 3,3′-dimethyl-4, 4′-diisocyanato diphenylmethane, crude MDI, 1,5-naphthylene diisocyanate, and the like;
{circle around (4)} araliphatic isocyanate with 8 to 15 carbon atoms, e.g., m- and/or p-xylylene diisocyanate (hereinafter referred to as XDI), &agr;,&agr;,&agr;′,&agr;′-tetramethyl xylylene diisocyanate (hereinafter referred to as TMXDI), and the like;
{circle around (5)} modified polyisocyanates from these, e.g., modified diisocyanates having a carbodiimide group, an urethodione group, an urethoimine group or an urea group; and
{circle around (6)}
Kinsho Toshihiko
Nomura Takao
Tanaka Keiji
Yabuta Takashi
Yokouchi Keiichi
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Sanyo Chemical Industries Ltd.
Sergent Rabon
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