Plastic and nonmetallic article shaping or treating: processes – With printing or coating of workpiece – Coating or impregnating workpiece before molding or shaping...
Reexamination Certificate
2001-05-16
2004-09-21
Eashoo, Mark (Department: 1732)
Plastic and nonmetallic article shaping or treating: processes
With printing or coating of workpiece
Coating or impregnating workpiece before molding or shaping...
C264S331160, C156S180000
Reexamination Certificate
active
06793855
ABSTRACT:
TECHNICAL FIELD
The invention relates to polyisocyanurate systems, fiber reinforced polyisocyanurate matrix composites, and manufacture of those composites by pultrusion.
BACKGROUND ART
Pultrusion is a highly cost effective method for making fiber reinforced, resin matrix composites. The primary raw materials used in pultrusion are resin and reinforcement. Fillers and additives such as calcium carbonate, clay, mica, pigments, UV stabilizers can be added to the resin to enhance the physical, chemical and mechanical properties of the pultruded product.
Pultrusion is typically done by the injection die or open bath process. The open bath process is the most common. The injection die process, however, is gaining importance due to environmental concerns about the large amounts of volatile contaminants released in the open bath process.
In a typical open bath process, reinforcement material in the form of fibers, mat or roving is pulled continuously through an open bath of resin to produce an impregnated reinforcement. The impregnated reinforcement is pulled through form plates to remove excess resin, and then through a curing die to cure the resin and yield a finished product.
In the injection die pultrusion process, reinforcement material is passed through a closed injection die that has resin injection ports. The resin is injected under pressure through the ports to impregnate the reinforcement material. The impregnated reinforcement is pulled through the injection die to produce a shaped product.
Resins which have been used in the open bath and injection die methods of pultrusion include thermoset resins such as unsaturated polyester, epoxy, phenolics, methacrylates and the like, as well as thermoplastic resins such as PPS, ABS, Nylon 6. Blocked polyurethane prepolymers also have been used. Polyester and epoxy resins are generally slower reacting than polyisocyanurates. In addition, the use of blocked polyurethane resins in pultrusion has the disadvantage of deblocking of the isocyanate which creates environmental concerns.
A need therefore exists for resins such as polyisocyanurate and polyurethane resins which may be used in pultrusion, especially injection die pultrusion, without these disadvantages.
DISCLOSURE OF THE INVENTION
The invention relates to polyisocyanurate systems, preferably miscible polyisocyanurate systems, having an isocyanate component and a polyol component. The polyol component includes any of polyester polyols and polyether polyols. One or more polyester polyols may be blended with one or more polyether polyols in any ratio for use in the polyol component.
The polyether polyols have a functionality of about 2 to about 6 and a molecular weight of about 300-6000. The polyol component also includes a catalyst capable of initiating both a urethane and an isocyanurate reaction. The isocyanate can be an isocyanate prepolymer. The isocyanate and the polyol component can be present in a ratio of about 0.3 to about 9.0 in an amount sufficient to yield an index of about 200 to about 900.
The polyol component also can include a chain extender such as glycerols and diols having at least about 2 hydroxyl groups and a molecular weight less than about 300. When a chain extender is present, the polyol may be present in an amount of up to about 1-99% and the chain extender may be may be present in an amount of up to about 1-99% based on total weight of the polyol component.
A preferred polyisocyanurate system includes an isocyanate component and a polyether polyol component where the polyether polyol is polyethylene oxide capped polypropylene oxide polyether polyol having ethylene oxide content of about 21%, a functionality of 2, and a hydroxyl value of 30 mg KOH/gm, the chain extender is dipropylene glycol, and the isocyanate is a mixture of 2,4′ MDI,4,4′ MDI and pMDI having about 19.5% 2,4′-MDI, 60.9% 4,4′-MDI, about 19.6% p-MDI, and an NCO value of 32.5. The polyisocyanurate systems, at an index of from about 300 to about 700 fully cure at 120-140 C. with an isocyanate conversion of about 90%. Another preferred polyisocyanurate system includes an isocyanate component and a polyether polyol component where the polyether polyol is PPG425 and the isocyanate is a mixture of 2,4′ MDI,4,4′ MDI and pMDI having about 19.5% 2,4′-MDI, 60.9% 4,4′-MDI, about 19.6% p-MDI, and an NCO value of 32.5.
The invention also relates to a pultrusion process for preparing a cured polyisocyanurate fiber reinforced polymer composite. The process entails pulling continuous fibers through an impregnation die, supplying a polyol component having a catalyst capable of initiating both a urethane reaction and a isocyanurate reaction, and an isocyanate component to a static mixer to produce a polyisocyanurate reaction mixture and feeding the reaction mixture to the impregnation die, contacting the fibers with the precursor mixture in the impregnation chamber for a time period and at a temperature sufficient to cause substantial polymerization of the reaction mixture within the impregnation chamber to produce a composite of fibers coated by the polyisocyanurate reaction mixture, directing the composite of coated fibers through a heated curing die to at least partially cure the polyisocyanurate reaction mixture to produce a solid fiber reinforced polyisocyanurate matrix composite, and drawing the cured composite from the die. The temperature in the impregnation chamber is less than the temperature required to initiate a polyisocyanurate reaction. The fibers are at ambient temperature before they enter the impregnation die. The fibers and the reaction mixture are supplied concurrently to the impregnation die. During pultrusion, the polyisocyanurate reaction mixture may be present in the injection die for less than about 50 seconds.
The polyisocyanurate systems of the invention are two component systems. Mixing of the two components can be achieved by using a static or dynamic mixer. A static mixer is preferred. Type I and Type II miscible two component polyisocyanurate systems are preferred.
Having summarized the invention, the invention will now be described in detail by reference to the following disclosure and non-limiting examples.
MODES FOR CARRYING OUT THE INVENTION
Glossary
The following names and abbreviations are understood to have the meanings defined below:
1. 1,4 BD is 1,4 butane diol;
2. 1,3 BD is 1,3 butane diol;
3. 2,3 BD is 2,3 butane diol;
4. 1,2 PD is 1,2 propane diol;
5. 2m 1,3 PD is 2-methyl-1,3-propane diol;
6. BiCat 8 is Bismuth-Zinc Neodeconate from Shepherd Chemical Co.;
7. Dabco DC 1027 is 30% triethylenediamine (TEDA) in Ethylene. Dabco 33LV is TEDA in DPG from Air Products and Chemicals, Allentown, Pa.
8. Dabco K15 is a catalyst of a potassium salt in a glycol from Air Products and Chemicals, Allentown, Pa.;
9. Dabco T-12 is 100% dibutyl tin dilaurate from Air Products and Chemicals, Allentown, Pa.;
10. Dabco T-45 is a potassium carboxylate catalyst from Air Products and Chemicals, Allentown, Pa.;
11. Dabco TMR is a tetra alkylammonium 2-ethylhexonate dissolved in DPG, from Air Products.;
12. Fomrez UL-29 is a mixture of octylmercapto acetate in a polyol carrier available from Witco Corporation, Greenwich, Conn.;
13. DEG is diethylene glycol;
14. DPG is dipropylene glycol;
15. Glycerin is 99.5% pure trihydroxy alcohol from Quaker Chemical Co.;
16. Isocyanate A is polymeric MDI having an MDI content of about 44 wt. % and an NCO value of about 30.7 from Huntsman Polyurethanes;
17. Isocyanate B is uretonimine modified 4,4′ MDI having an NCO value of 29 from Huntsman Polyurethanes;
18. Isocyanate C is a mixture of 2,4′ MDI,4,4MDI and pMDI having about 9.4% 2,4′-MDI, 60.9% 4,4′-MDI, about 29.7% p-MDI, and an NCO value of 32.1 from Huntsman Polyurethanes.
19. Isocyanate D is a mixture of 2,4′ MDI,4,4′ MDI and pMDI having about 19.5% 2,4′-MDI, 60.9% 4,4′-MDI, about 19.6% p-MDI, and an NCO value of 32.5 from Huntsman Polyurethanes.
20. Isocyanate E is a softblock MDI prepolymer formed from
Cheolas Evan H.
Eling Berend
Joshi Ravi R
Eashoo Mark
Graham Nicole
Huntsman International LLC
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