Stock material or miscellaneous articles – Composite – Of polyamidoester
Reexamination Certificate
1999-01-08
2002-09-17
Sergent, Rabon (Department: 1711)
Stock material or miscellaneous articles
Composite
Of polyamidoester
C156S078000, C156S307100, C156S307300, C427S373000, C427S372200, C427S393500, C428S036500, C428S160000, C428S308400, C428S317100, C428S317500, C428S317700, C428S319300, C521S137000, C521S159000, C521S170000, C521S172000, C521S173000, C521S174000, C521S176000
Reexamination Certificate
active
06451430
ABSTRACT:
BACKGROUND OF THE INVENTION
Polyester resins are synthetic resins which are polycondensation products prepared by the reaction of dicarboxylic acids with dihydroxy alcohols. Unsaturated polyester resin compositions contain ethylenic unsaturation, usually introduced by unsaturated diols and acids or both, either alone or in combination with saturated diols and acids. Unsaturated polyester resins are cross linked with a compatible monomer, such as a styrene monomer or an acrylic monomer, in amounts ranging from 0% to 50% by weight, thus providing in the presence of a catalyst, like a peroxide, a cured polyester thermosetting resin. Unsaturated polyester resins are prepared typically by maleic and fumaric acids, which may include saturated acids, such as phthalic and adipic acids, and which unsaturated acids may be acid anhydrides. Generally, the dihydroxy alcohols are ethylene, propylene, diethylene and dipropylene glycols. Cross linking agents are typically a styrene monomer and diallyl phthalate.
Unsaturated polyester resin compositions have long been used to prepare composite laminate-type structures. Such laminate structures have often employed a lightweight core material, such as balsa wood, cut or sprayed rigid polyurethane foam and PVC foams, as the core material to produce such composite structures. Generally, an unsaturated resin composition is applied to one or both surfaces of the lightweight core material over a gel coating layer, typically containing pigments to form a top surface of a composite laminate structure. The rigid polyurethane foams employed in such core materials have been cut to dimensions; however, rigid polyurethane foams have also been applied as a spray to the backing layer of an unsaturated polyester resin on the gelcoat layer to form a composite laminate.
Polyurethane products are produced by the condensation reaction of a polyisocyanate, such as a diisocyanate, and a hydroxyl-containing material, such as a polyol, to provide both flexible and rigid polyurethane foam having densities varying from about two to thirty pounds per cubic feet. Rigid polyurethane foams used as core materials are prepared by employing a polyether, such as a polypropylene glycol reacted with a diisocyanate in the presence of water as a blowing agent, and a catalyst (amines, such as a polyethanol polyamine, like diethanol tetramine, and metal salts, such as tin compounds, like dialkyl tin), so that the water reacts with the diisocyanate to cause cross linking and also produce carbon dioxide which produces a polyurethane rigid foam material. Other blowing agents may be employed, such as fluoro hydrocarbons or hydrocarbons and other volatile materials. Generally, rigid polyurethane foams are based on polyethers made from sorbitol, methyl glucoside, sucrose, or combinations thereof. Rigid polyurethane foams are employed for forming lightweight, rigid composite structures, particularly where an unsaturated polyester resin composition is employed as a top or bottom layer with the rigid polyurethane foam material.
The preparation of composite structures using a core material and unsaturated polyester resin layers with core materials, particularly polyurethane rigid foams, share a common problem in that no chemical bond occurs between the core material and the cured unsaturated polyester resin layer composition in contact with the core material creating a structural weakness in the composite laminate product.
It is desirable therefore to provide for a new and improved polyurethane foam composition which may be employed with unsaturated polyester resin compositions, particularly where the polyurethane rigid foam compositions form a core material in a composite, lightweight structural laminate, and wherein an unsaturated polyester resin composition is employed as one or more layers on the core material, and the cured polyester resin layer forms a strong and effective bond with the foam core material.
SUMMARY OF THE INVENTION
The invention concerns a foamable polyurethane composition suitable for use in preparing a core material in a laminate for bonding with an unsaturated polyester resin composition and to the method of preparing a hybrid, structurally rigid polyurethane-unsaturated polyester resin composite structure and the product so prepared.
The invention comprises a foamable polyurethane composition for the preparation of rigid foam polyurethane and adapted for use in bonding to an unsaturated polyester resin composition, typically employed as an unsaturated polyester resin layer in contact with at least one surface of the rigid foam polyurethane composition. The foamable polyurethane composition comprises: a) polyol b) a catalyst, for example, a gelling catalyst and a blowing catalyst, to carry out the polyurethane reaction; c) a blowing agent to provide a rigid polyurethane foam; and d) a polyisocyanate, such as MDI or prepolymer or diisocyanate to react with the polyol with the polyisocyanate generally being in a stoichiometric amount or in a slight excess.
The polyurethane composition also includes or has added thereto an additive organic compound having an active hydroxyl group which reacts with the polyisocyanate and which also contains an available, unreacted ethylenically unsaturated group which reacts subsequently with the monomer-containing unsaturated polyester resin composition applied to the rigid polyurethane foam, thereby providing a strong chemical bond between the rigid polyurethane foam and the cured unsaturated polyester resin composition layer. The additive compound comprises from about 1% to 20% by weight of the polyisocyanate of the polyurethane composition. The ethylenically unsaturated group of the foamable polyurethane composite is available for reaction with the monomer in the unsaturated polyester resin, so that on curing of the unsaturated polyester resin layer, such as by the use of organic peroxide, blown with or without the use of metal salt promoters and accelerators, a strong chemical bond is formed between the rigid polyurethane foam core material, typically as an inner core section of a composite laminate, and the cured unsaturated polyester resin layer.
The additive may be a prepolymer having free isocyanate groups and prepared by reacting said additive organic compound with said active hydroxyl group with separately a polyisocyanate or said polyisocyanate to form a prepolymer, the prepolymer having an unreacted, ethylenically unsaturated group after the reaction with the polyisocyanate to react with a peroxide-curable monomer-containing unsaturated polyester resin composition.
The polyols useful in the polyurethane compositions are selected to provide for a rigid or semirigid polyurethane foam and typically would be a polyol, such as a polyether polyol made from sorbitol, methyl glucoside, or sucrose, a glycerine polyol and hydroxyl amines, and combinations thereof. Aromatic polyesters useful in the polyurethane composition generally comprise saturated aromatic polyesters, for example, prepared by the reaction of phthalic acid, like an dialkyl (i.e. dimethyl) terephthalic acid, with a polyol, such as a polyalkylene glycol, like diethylene or dipropylene glycol, or a terephthalate-ethylene glycol polyester polyol, to provide the aromatic polyester polyol. The polyurethane composition may contain combinations of the polyether polyols and the saturated phthalic-polyol esters. The blowing agent in the polyurethane composition typically and preferred is water; however, other blowing agents, such as fluorocarbon blowing agents, such as chlorocarbon blowing agents, may also be employed, as well as other volatile hydrocarbons. The catalyst employed in the polyurethane composition constitutes a wide variety of catalysts which accelerate the polyurethane reaction including amines, metal carboxylates, particularly tin soaps and organic tin compounds, alone and in combination, used in a catalytic amount, e.g. of 0.01% to 2.0% by weight.
The polyisocyanate generally comprises a diisocyanate, either aliphatic or aromatic, and particularly is MDI or an
Hehr International Inc.
IP Legal Strategies Group P.C.
Meyer-Leon Esq. Leslie
Sergent Rabon
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