WO2009045417A1 - Internal combustion engine gasket systems - Google Patents

Abstract

Metal plated organic polymer compositions are useful as internal combustion engine gasket systems. Such gasket systems may have lighter weight, and/ or superior corrosion resistance, than conventional gasket systems.

Description

INTERNAL COMBUSTION ENGINE GASKET SYSTEMS

FIELD OF THE INVENTION Metal plated organic polymers are useful for internal combustion engine gasket systems.

TECHNICAL BACKGROUND

Vehicles which contain internal combustion engines such as automobiles, trucks, motorcycles, scooters, rec- reational and all terrain vehicles, farm equipment such as tractors, and construction equipment such as bulldozers and graders are of course important items in modern society, and they are made of a myriad of parts. Also important are stationary internal combustion engines such as those used to power generators . Many of these parts must have certain minimum physical properties such as stiffness and/or strength. Traditionally these types of parts have been made from metals such as steel, aluminum, zinc, and other metals, but in recent decades organic polymers have been increasingly used for such parts for a variety of reasons. Such polymeric parts are often lighter, and/or easier (cheaper) to fabricate especially in complicated shapes, and/or have better corrosion resistance. However such polymeric parts have not replaced metals in some application because the they are not stiff and/or strong enough, or have other property deficiencies compared to metal .

Thus vehicle manufacturers have been searching for ways to incorporate more polymeric materials into their vehicles, including engines, for a variety of reasons, for example to save weight, lower costs, or provide more design freedom. Thus improved polymeric gasket systems have been sought by vehicle manufacturers. It has now been found that metal plated organic polymeric gasket systems have the properties desired.

Metal plated polymeric parts have been used in vehicles, especially for ornamental purposes. Chrome or nickel plating of visible parts, including polymeric parts, has long been done. In this use the polymer is coated with a thin layer of metal to produce a pleasing visual effect. The amount of metal used is generally the minimum required to produce the desired visual effect and be durable.

US Patent 4,406,558 describes a gudgeon pin for an internal combustion engine which is metal plated polymer. US Patent 6,595,341 describes an aluminum plated plastic part for a clutch. Neither of these patents mentions in- ternal combustion engine gasket systems.

SUMMARY OF THE INVENTION

This invention concerns an internal combustion engine gasket system, comprising an organic polymer composition which is coated at least in part by a metal. This invention also concerns an internal combustion engine, comprising a gasket system which comprises an organic polymer composition which is coated at least in part by a metal .

DETAILS OF THE INVENTION Herein certain terms are used and some of them are defined below:

By an "organic polymer composition" is meant a composition which comprises one or more organic polymers. Preferably one or more of the organic polymers is the continuous phase.

By an "organic polymer" (OP) is meant a polymeric material which has carbon-carbon bonds in the polymeric chains and/or has groups in the polymeric chains which have carbon bound to hydrogen and/or halogen. Preferably the organic polymer is synthetic, i.e., made by man. The organic polymer may be for example a thermoplastic polymer (TPP) , or a thermoset polymer (TSP) .

By a "TPP" is meant a polymer which is not crosslinked and which has a melting point and/or glass transition point above 30°C, preferably above about 100⁰C, and more preferably above about 150⁰C. The highest melting point and/or glass transition temperature is also below the point where significant thermal degradation of the TPP occurs. Melting points and glass transition points are measured using ASTM Method ASTM D3418-82. The glass transition temperature is taken at the transition midpoint, while the melting point is measured on the second heat and taken as the peak of the melting endotherm. By a "TSP" is meant a polymeric material which is crosslinked, i.e., is insoluble in solvents and does not melt. It also refers to this type of polymeric material before it is crosslinked, but in the final gasket system, it is crosslinked. Preferably the crosslinked TSP compo- sition has a Heat Deflection Temperature of about 50⁰C, more preferably about 100⁰C, very preferably about 150⁰C or more at a load of 0.455 MPa (66 psi) when measured using ASTM Method D648-07.

By a polymeric "composition" is meant that the organic polymer is present together with any other additives usually used with such a type of polymer (see below) .

By "coated with a metal" is meant part or all of one or more surfaces of the gasket system is coated with a metal. The metal does not necessarily directly contact a surface of the organic polymer composition. For example an adhesive may be applied to the surface of the organic polymer and the metal coated onto that . Any method of coating the metal may be used (see below) . By "metal" is meant any pure metal or alloy or combination of metals. More than one layer of metal may be present, and the layers may have the same or different compositions . By a "gasket system" is meant a simple gasket

(normally for sealing) that is incorporated into a more complex system or assembly that accomplishes other functions besides simple sealing. It may incorporate a gasket carrier, a relatively rigid material on which the gasket may be "mounted" which allows easy and precise placement of the gasket into the assembly which is to be sealed. The gasket system, incorporating the gasket, may also perform other (optionally in addition to being a gasket carrier) functions such as comprising "extensions" which perform other functions. For example the gasket system may include an oil pan windage tray (see US Patent 6,019,071), or incorporate one or more sensors or sensor housings to monitor and/or control engine conditions.

Since a gasket system accomplishes one or more other functionalities than simple sealing, these other functionalities may require some minimum structural properties such as stiffness and/or strength. If this part of the gasket system is made of metal it may be heavy and relatively difficult to fabricate, and if made simply of an OP composition it may also be heavy (to achieve needed strength and/or stiffness) and therefore expensive. However this portion (or the whole) of the gasket system may be a metal coated OP composition, which is relatively easily fabricated and may be lighter in weight while hav- ing the requisite physical properties.

Thus the gasket system may be partially or fully metal coated. For example it may not be coated in the section where the gasket is but may be coated in sections which require higher strength and/or stiffness. It may be so coated on one or both sides, and/or in patterns to reinforce only those sections needing reinforcement. If fully coated on any surface exposed to a liquid and/or noxious gas it may also protect the OP composition that may be degraded by the liquid and/or gas. In appropriate situations where the OP composition may be worn by an abrasive material, it may protect the OP composition surface from wear because metals are often harder than OP compositions . Particularly around the gasket itself, put also possibly in other portions of the gasket system, it is important that the gasket system not warp or deform so as to maintain a good seal . Thus it may be advantageous to metal coat the section holding the gasket to stabilize it, and it may even be more advantageous to use a thicker coating of metal in this section.

Useful TSPs include epoxy, phenolic, and melamine resins. Parts may be formed from the thermoset resin by- conventional methods such as reaction injection molding or compression molding.

Useful TPPs include poly (oxymethylene) and its copolymers; polyesters such as poly (ethylene terephtha- late) , poly (1 , 4-butylene terephthalate) , poly(l,4- cyclohexyldimethylene terephthalate), and poly(l,3- poropyleneterephthalate) ; polyamides such as nylon-6,6, nylon-6, nylon- 12, nylon- 11, and aromatic-aliphatic co- polyamides; polyolefins such as polyethylene (i.e. all forms such as low density, linear low density, high density, etc.), polypropylene, polystyrene, polysty- rene/poly (phenylene oxide) blends, polycarbonates such as poly (bisphenol-A carbonate); fluoropolymers including perfluoropolymers and partially fluorinated polymers such as copolymers of tetrafluoroethylene and hexafluoropro- pylene, poly(vinyl fluoride), and the copolymers of eth- ylene and vinylidene fluoride or vinyl fluoride; poly- sulfides such as poly (p-phenylene sulfide); polyetherke- tones such as poly (ether-ketones) , poly (ether-ether- ketones) , and poly (ether-ketone-ketones) ; poly (etherimides) ; acrylonitrile-1, 3-butadinene-styrene copolymers,- thermoplastic (meth) acrylic polymers such as poly (methyl methacrylate) ; and chlorinated polymers such as poly (vinyl chloride), polyimides, polyamideimides, vinyl chloride copolymer, and poly (vinylidene chloride) . "Thermotropic liquid crystalline polymer" (LCP) herein means a polymer that is anisotropic when tested using the TOT test or any reasonable variation thereof, as described in U.S. Patent 4,118,372, which is hereby incorporated by reference. Useful LCPs include polyesters, poly (ester-amides) , and poly (ester-imides) . One preferred form of LCP is "all aromatic", that is all of the groups in the polymer main chain are aromatic (except for the linking groups such as ester groups) , but side groups which are not aromatic may be present. The TPPs may be formed into parts by the usual methods, such as injection molding, thermoforming, compression molding, extrusion, and the like.

The OP, whether a TSP, TPP or other polymer composition may contain other ingredients normally found in such compositions such as fillers, reinforcing agents such as glass and carbon fibers, pigments, dyes, stabilizers, toughening agents, nucleating agents, antioxidants, flame retardants, process aids, and adhesion promoters. Another class of materials may be substances that improve the adhesion to the resin of the metal to be coated onto the resin. Some of these may also fit into one or more of the classes named above.

The OP (composition) should preferably not soften significantly at the expected maximum operating tempera- ture of the gasket system. Since it is often present at least in part for enhanced structural purposes, it will better maintain its overall physical properties if no softening occurs. Thus preferably the OP has a melting point and/or glass transition temperature and/or a Heat Deflection Temperature at or above the highest use temperature of the OP.

The OP composition (without metal coating) should also preferably have a relatively high flexural modulus, preferably at least about 1 GPa, more preferably at least about 2 GPa, and very preferably at least about 10 GPa. Flexural modulus is measured by ASTM Method D790-03, Procedure A, preferably on molded parts, 3.2 mm thick (1/8 inch), and 12.7 mm (0.5 inch) wide, under a standard laboratory atmosphere. Since these are structural parts, and are usually preferred to be stiff, a higher flexural modulus improves the overall stiffness of the metal coated gasket system (MCGS) .

The OP composition may be coated with metal by any known methods for accomplishing that, such as vacuum deposition (including various methods of heating the metal to be deposited) , electroless plating, electroplating, chemical vapor deposition, metal sputtering, and electron beam deposition. Preferred methods are elec- troless plating and electroplating, and a combination of the two. Although the metal may adhere well to the OP composition without any special treatment, usually some method for improving adhesion will be used. This may range from simple abrasion of the OP composition surface to roughen it, addition of adhesion promotion agents, chemical etching, functionalization of the surface by exposure to plasma and/or radiation (for instance laser or UV radiation) or any combination of these. Which methods may be used will depend on the OP composition to be coated and the adhesion desired. Methods for improving the adhesion of coated metals to many OPs are well known in the art. More than one metal or metal alloy may be plated onto the organic resin, for example one metal or alloy may be plated directly onto the organic resin surface because of its good adhesion, and another metal or alloy may be plated on top of that because it has a higher strength and/or stiffness.

Useful metals and alloys to form the metal coating include copper, nickel, iron-nickel, cobalt, cobalt - nickel, and chromium, and combinations of these in different layers. Preferred metals and alloys are copper, nickel, and iron-nickel, and nickel is more preferred. The surface of the organic resin of the structural part may be fully or partly coated with metal. In different areas of the part the thickness and/or the number of metal layers, and/or the composition of the metal layers may vary.

When electroplating it is known that grain size of the metal deposited may be controlled by the electroplating conditions, see for instance U.S. Patents 5,352,266 and 5,433,797 and U.S. Patent Publications 20060125282 and 2005020525, all of which are hereby included by reference. In one preferred form at least one of the metal layers deposited has an average grain size in the range of about 5 nm to about 200 nm, more preferably about 10 nm to about 100 nm. In another preferred form of electroplated metal, the metal has an average grain size of at least 500 nm, preferably at least about 1000 nm, and/or an average maximum grain size of about 5000 nm. For all these grain size preferences, it is preferred that that thickest metal layer, if there is more than one layer, be the specified grain size. The thickness of the metal layer (s) deposited on the organic resin is not critical, being determined mostly by the desire to minimize weight while providing certain minimum physical properties such as modulus, strength and/or stiffness. These overall properties will depend to a certain extent not only on the thickness and type of metal or alloy used, but also on the design of the structural part and the properties of the organic resin composition. In one preferred embodiment the flexural modulus of the metal coated gasket system is at least about twice, more preferably at least about thrice, the flexural modulus of the uncoated OP composition. This is measured in the following way. The procedure used is ISO Method 178, using molded test bars with dimensions 4.0 mm thick and 10.0 mm wide. The testing speed is 2.0 mm/min. The OP composition from which the gasket system are made is molded into the test bars, and then some of the bars are completely coated (optionally except for the ends which do not affect the test results) with the same metal using the same procedure used to coat the gasket system. The thickness of the metal coating on the bars is the same as on the gasket system. If the thickness on the gasket system varies, the test bars will be coated to the great- est metal thickness on the gasket system. The flexural moduli of the coated and uncoated bars are then measured, and these values are used to determine the ratio of flexural moduli (flexural modulus of coated/flexural modulus of uncoated) . Generally speaking the thicker the metal coating, the greater the flexural modulus ratio between the uncoated and coated OP part .

For use as MCGSs, it is also important in many instances that the plated OP composition be tough, for example be able to withstand impacts. It has surprisingly been found that some of the metal plated OP compositions of the present invention are surprisingly tough. It has previously been reported (M. Corley, et al . , Engineering Polyolefins for Metallized Decorative Applications, in Proceedings of TPOs in Automotive 2005, held June 21-23, 2005, Geneva Switzerland, Executive Conference Management, Plymouth, MI 48170 USA, p. 1-6) that unfilled or lightly filled polyolefin plaques have a higher impact energy to break than their Cr plated analog. Indeed the impact strength of the plated plaques range from 50 to 86 percent of the impact strength of the unplated plaques. As can be seen from Examples 2-7 below, the impact maximum energies of the plated plaques are much higher than those of the unplated plaques. It is believed this is due to the higher filler levels of the OP compositions used, and in the present parts it is preferred that the OP composition have at least about 25 weight percent, more preferably about 35 weight percent, especially preferably at least about 45 weight percent of filler/reinforcing agent present. A preferred maximum amount of filler/reinforcing agent present is about 65 weight percent . These percentages are based on the total weight of all ingredients present. Typical reinforcing agents/fillers include carbon fiber, glass fiber, aramid fiber, particulate minerals such as clays (various types), mica, silica, calcium carbonate (including limestone) , zinc oxide, wollastonite, carbon black, titanium dioxide, alumina, talc, kaolin, microspheres, alumina trihydrate, calcium sulfate, and other minerals. It is preferred that the ISO179 impact energy (see below for procedure) of the metal plated MCGS be 1.2 times or more the impact energy of the unplated OP composition, more preferably 1.5 times or more. The test is run by making bars of the OP composition, and plating them by the same method used to make the MCGS, with the same thickness of metal applied. If the MCGS is metal plated on both sides (of the principal surfaces) , the test bars are plated on both sides, while if the MCGS is plated on one side (of the principal surfaces) the test bars are plated on one side. The impact energy of the plated bars are compared to the impact energy of bars of the unplated OP composition.

Preferably the metal coating will about 0.010 mm to about 1.3 mm thick, more preferably about 0.025 mm to about 1.1 mm thick, very preferably about 0.050 to about 1.0 mm thick, and especially preferably about 0.10 to about 0.7 mm thick. It is to be understood that any minimum thickness mentioned above may be combined with any maximum thickness mentioned above to form a different preferred thickness range. The thickness required to attain a certain flexural modulus is also dependent on the metal chosen for the coating. Generally speaking the higher the tensile modulus of the metal, the less will be needed to achieve a given stiffness (flexural modulus) . Preferably the flexural modulus of the uncoated OP composition is greater than about 200 MPa, more prefera- bly greater than about 500 MPa, and very preferably greater than about 2.0 GPa. Example 1

Zytel® 70G25, a nylon 6,6 product containing 25 weight percent chopped glass fiber available from E.I. DuPont de Nemours & Co., Inc. Wilmington, DE 19898 USA, was injection molded into bars whose central section was 10.0 mm wide and 4.0 mm thick. Before molding the polymer composition was dried at 80⁰C in a dehumidified dryer. Molding conditions were melt temperature 280-300⁰C and a mold temperature of 80⁰C. Some of the bars were etched using Addipost® PM847 etch, reported to be a blend of ethylene glycol and hydrochloric acid, and obtained from Rohm Sc Haas Chemicals Europe. Less than 1 μm of copper was then electrolessly deposited on the surface, followed by 8 μm of electrolytically deposited copper, followed by 100 μm of nickel, on all surfaces. The flexural modulus was then determined, as described above, on the uncoated and metal coated bars. The uncoated bars had a flexural modulus of 7.7 GPa, and the metal coated bars had a flexural modulus of 29.9 GPa. Examples 2-7

Ingredients used, and their designations in the tables are:

Filler 1 - A calcined, aminosilane coated, kaolin, Polarite^® 102A, available from Imerys Co., Paris, France.

Filler 2 - Calmote^® UF, a calcium carbonate available from Omya UK, Ltd., Derby DE21 6LY, UK.

Filler 3 - Nyad^® G, a wollastonite from Nyco Minerals, Willsboro, NY 12996, USA. Filler 4 - M10-52 talc manufactured by Barretts

Minerals, Inc., Dillon, MT, USA.

Filler 5 - Translink^® 445, a treated kaolin available from BASF Corp., Florham Park, NJ 07932, USA.

GF 1 - Chopped (nominal length 3.2 mm) glass fi- ber, PPG^® 3660, available from PPG Industries, Pittsburgh, PA 15272, USA.

GF 2 - Chopped (nominal length 3.2 mm) glass fiber, PPG^® 3540, available from PPG Industries, Pittsburgh, PA 15272, USA. HSl - A thermal stabilizer containing 78% KI,

11% aluminum distearate, and 11% CuI (by weight) .

HS2 - A thermal stabilizer contain 7 parts KI, 11 parts aluminum distearate, and 0.5 parts CuI (by weight) . Lube - Licowax® PE 190 - a polyethylene wax used as a mold lubricant available from Clariant Corp. Charlotte, NC 28205, USA.

Polymer A - Polyamide-6 , 6 , Zytel^® 101 available from E.I. DuPont de Nemours & Co., Inc. Wilmington, DE 19810, USA.

Polymer B - Polyamide-6, Durethan^® B29 available from Laxness AG, 51369 Leverkusen, Germany.

Polymer C - An ethylene/propylene copolymer grafted with 3 weight percent maleic anhydride.

Polymer D - A copolyamide which is a copolymer of terephthalic acid, 1, 6-diaminohexane, and 2-methyl-l, 5- diaminopentane, in which each of the diamines is present in equimolar amounts. Polymer E - Engage^®8180, an ethylene/l-octene copolymer available by Dow Chemical Co., Midland, MI, USA.

Wax 1 - N, N' -ethylene bisstearamide

Wax 2 - Licowax^® OP, available from Clariant Corp. Charlotte, NC 28205, USA. The organic polymer compositions used in these examples are listed in Table 1. The compositions were made by melt blending of the ingredients in a 30 mm Werner & Pfleiderer 30 mm twin screw extruder.

Table 1

The test pieces, which were 7.62x12.70x0.30 cm plaques or ISO 527 test bars, 4 mm thick, gauge width 10 mm, were made by injection molding under the conditions given in Table 2. Before molding the polymer compositions were dried for 6-8 hr in dehumidified air under the temperatures indicated, and had a moisture content of <0.1% before molding.

Table 2

These test specimens were then etched in sulfochro- mic acid or Rohm & Haas Chrome free etching solution, and rendered conductive on all surface by electroless deposition of a very thin layer of Ni. Subsequent galvanic deposition of 8 μm of Cu was followed by deposition of a 100 μm thick layer of fine grain N-Fe (55-45 weight) using a pulsed electric current, as described in US Patent 5,352,266 for making fine grain size metal coatings.

The samples were tested by one or both of the following methods :

ISO 6603-2 - Machine Instron^® Dynatup Model 8250, Support Ring 40 mm dia, Hemispherical Tup 20 mm dia, Ve- locity 2.2 m/s, Impacter weight 44.45 kg, Temperature

23°C, Condition dry as made. Test were run on the plaques described above .

ISO 179-leU - Sample Unnotched, Pendulum energy 25 J, Impact velocity 3.7 m/s, Temperature 23°C, Condition dry as made. Tests were run on the gauge part of the ISO 527 test bars described above.

Testing results are given in Table 3.

Table 3

Claims

CLAIMS What is claimed is:

1. An internal combustion engine gasket system, comprising, an organic polymer composition which is coated at least in part by a metal .

2. The internal combustion engine gasket system as recited in claim 1 wherein said organic polymer, if a thermoplastic has a melting point and/or a glass transition point of about 150⁰C or more, or if a thermoset has a heat deflection temperature of 150⁰C or more at a load of 0.455 MPa.

3. The internal combustion engine gasket system as recited in any one of claims 1 to 2 wherein at least one layer of said metal coating has an average grain size of about 5 nm to about 200 nm.

4. The internal combustion engine gasket system as recited in any one of claims 1 to 2 wherein a thickest layer of said metal coating has an average grain size of at least about 500 nm.

5. The internal combustion engine gasket system as recited in any one of claims 1 to 5 wherein said metal coating is about 0.010 mm to about 1.3 mm thick.

6. The internal combustion engine gasket system as recited in any one of claims 1 to 4 wherein said metal coating is about 0.025 mm to about 1.3 mm thick.

7. An internal combustion engine, comprising, the internal combustion engine gasket system of any one of claims 1 to 6.

INTERNATIONAL SEARCH REPORT International application No PCT/US 08/11340

A CLASSIFICATION OF SUBJECT MATTER

IPC(8) - F02F 11/00 (2008.04)

USPC - 277/595 According to International Patent Classification (IPC) or to both national classification and IPC

B FIELDS SEARCHED

Minimum documentation searched (classification system followed by classification symbols) USPC 277/595

Documentation searched other than minimum documentation to the extent that such documents are included in the fields searched USPC 277/595, 592, 428/457, 106/1 05, 264/45 1, 46 7 IPC(8) F02F 11/00 (2008 04)

Electronic data base consulted during the international search (name of data base and, where practicable, search terms used)

PubWEST (PGPB, USPT, USOC, EPAB, JPAB), GOOGLE, GOOGLE Patents

Search terms gasket, elia, day, engine, internal, combustion, metal, coat$, aluminum, organic, polymer

C DOCUMENTS CONSIDERED TO BE RELEVANT

Category* Citation of document, with indication, where appropriate, of the relevant passages Relevant to claim No

US 3,839,078 A (BIRCHALL et al ) 01 October 1974 (01 10 1974), col 1, In 3-5, col 2, In 1-20, 1-4 col 19, In 23-31, col 20, In 16-21

US 3,970,322 A (STECHER et al ) 20 July 1976 (2007 1976), entire document 1-4

US 2005/0187325 A1 (YUAN et al ) 25 August 2005 (2508 2005), entire document 1-4

Further documents are listed in the continuation of Box C

Special categories of cited documents "T" later document published after the international filing date or priority

"A" document defining the general state of the art which is not considered date and not in conflict with the application but cited to understand to be of particular relevance the principle or theory underlying the invention

"E" earlier application or patent but published on or after the international "X" document of particular relevance, the claimed invention cannot be filing date considered novel or cannot be considered to involve an inventive

"L" document which may throw doubts on priority claim(s) or which is step when the document is taken alone cited to establish the publication date of another citation or other special reason (as specified) "Y" document of particular relevance, the claimed invention cannot be considered to involve an inventive step when the document is

"O" document referring to an oral disclosure, use, exhibition or other combined with one or more other such documents, such combination means being obvious to a person skilled in the art

"P" document published prior to the international filing date but later than the priority date claimed "&" document member of the same patent family

Date of the actual completion of the international search Date of mailing of the international search report 16 November 2008 (16 11 2008) 12 DEC 2008

Name and mailing address of the ISAAJS Authorized officer

Mail Stop PCT, Attn ISA/US, Commissioner for Patents Lee W Young

O Box 1450, Alexandπa, Virginia 22313-1450

PCT Hθlpdβsk 571 272-4300 Facsimile No 571-273-3201 PCT OSP 571 272 7774

Form PCT/ISA/210 (second sheet) (April 2007)