Polyurea Polymers from Secondary Polyether Polyamines

Field of the Invention The present invention relates generally to polyurea polymers. More specifically, it relates to the preparation of polymeric reaction products formed from the reaction

between an organic isocyanate and a polyamine, wherein the polyamine is a secondary

polyether polyamine.

Background Information

Polyurea polymers are polymers which are formed from the reaction of one or

more organic isocyanates with one or more organic polyamines. Polyureas can be formed

by bringing the organic isocyanate(s) component(s) in contact with the organic polyamine(s) using static mixing equipment, high-pressure impingement mixing

equipment, low-pressure mixing equipment, roller with mixing attachments and simple

hand mixing techniques, as such techniques are known to those skilled in the art.

Polyurea polymers are useful in caulks, adhesives, sealants, coatings, foams, and many

other applications. Specific examples include, but are not limited to, truck-bed liners, concrete coatings, metal coatings, concrete caulks, roof coatings, decorative coatings, and

steel coatings. Polyurea polymers are widely used in the coatings and paint industries. In many

of the commercially-available isocyanate reactants used to form polyureas, the isocyanate content ("% NCO") of the basic isocyanate building blocks is considered by some individuals skilled in the art to be inherently too high for good polyurea formation. In

such cases, the isocyanate content may be reduced by pre-reacting the isocyanate with an

amine or hydroxyl containing compound; however, some view altering the isocyanate

content in this fashion to be unacceptable in view of the physical properties of the

materials formed in this manner, and employ alternate chemistries to achieve their goals. Polyetheramines have also been used for reducing the isocyanate content of some

isocyanates, such as those polyetheramines manufactured and sold by HUNTSMAN LLC

of Houston, Texas under the JΕFFAMLNE® trademarked series of products, and the

various diamine polyetheramine products in the present specification are available from

HUNTSMAN LLC.

Summary of the Invention

The present invention provides polyurea polymers made from reacting secondary

polyether polyamines with one or more organic isocyanates. From a chemical standpoint,

the secondary polyetheramine group can react with an isocyanate group only once. This fact

inherently prevents the generally undesirable cross-linking reactions which may possibly occur

at an amine site when primary amines are used, owing to the presence of two active hydrogens

on the same nitrogen atom, which results in increased flexibility in the product, better polymer

"memory", and reduced isocyanate consumption on a per-mole basis. Another advantage of preparing polymers in accordance with the present invention is

the ability to form prepolymers with isocyanates where primary polyetheramines fail, which

provides formulators with the ability to formulate with isocyanates such as trimers of

hexamethylene diisocyanate, since the % NCO can now be manipulated into desired ranges.

Detailed Description

According to the present invention, secondary polyetheramine polyamines are

employed in the production of polyurea polymers. A given secondary polyether

polyamine differs from its primary analog in that the nitrogen atoms which in the primary

amine have two hydrogen atoms attached to them, only have a single hydrogen attached

to them, with one of the two hydrogens having been replaced by an alkyl group. We have

witnessed cases where primary polyetheramines have a detrimentally-fast reaction rate

which in many cases precludes the formation of polyurea materials having acceptable physical properties. We have discovered that the secondary polyether polyamines

dramatically decrease reaction times as compared to primary amines, while simultaneously

yielding polymeric ureas having advantageous physical properties over the polyurea

polymers of the prior art, such as increased tear strengths. The discovery of

advantageous physical properties is somewhat unexpected, in view of the known principle of hydrogen bonding, which is statistically decreased in the case of secondary amines

versus primary amines, by the simple fact that the primary amines have more hydrogens

available for hydrogen bonding. In fact, when a secondary amine is reacted with an

isocyanate, the hydrogen atom on the secondary amine is consumed; thus, the total hydrogen content of a polyurea produced using a secondary amine is less than that of a

polyurea polymer produced using the same isocyanate and the corresponding primary

amine. Importantly, the increase in tear strengths we have observed occur with no

significant losses in the tensile strengths of the materials. The present invention renders accessible many new end use applications in which secondary polyether polyamines are used in place of primary polyetheramines, to confer the benefits of polyetheramines

without the adverse high reactivity owing to the presence of the primary amine function in

the prior art materials and processes.

In one embodiment of the present mvention, the secondary polyether polyamines

are used to replace some primary polyetheramines in the amine blend used in the

production of a polyurea formulation. This results in an increase in the time before the

polyurea is completely polymerized "cured", which allows the polymer precursors to flow

smoothly to provide coatings and manufactures to be produced with fewer internal and surface defects. The end user or applicator is afforded more time to work with the fluid

polymer before its viscosity has increased to the point at which it can no longer worked,

which is sometimes referred to as the "work time".

In another embodiment, secondary polyether polyamines may be used to form pre- polymers with organic isocyanates for use in subsequently providing other polyurea

polymers. Many organic isocyanates cannot successfully be reacted to form prepolymers with primary polyetheramines due to crosslinking in the prepolymer. Another benefit of

the present invention which we have discovered is that it is now possible to provide

prepolymers from secondary polyether polyamines, for cases in which the analogous primary polyetheramine fails to yield such a prepolymer.

Secondary polyether polyamines may be obtained by reacting primary

polyetheramines with a di-alkyl ketone, aldehyde, or cyclic ketone or other carbonyl-

function containing molecule in the presence of hydrogen and a catalyst. The secondary polyether polyamines so obtained are light in color, have low viscosities, and remain liquid

at room temperature, which is a marked advantage which will be greatly appreciated by industrial producers of polyurea polymers.

As used in the present specification and the appended claims, the term "organic

isocyanate" includes a wide variety of materials recognized by those skilled in the art as

being useful in preparing polyurea and polyurethane polymer materials. Included within

this definition are both aliphatic and aromatic isocyanates, as well as one or more

prepolymers or quasi-prepolymers prepared using such isocyanates as a starting material,

as is generally well known in the art. Preferred examples of aliphatic isocyanates are of the type described in U.S. Pat. No. 4,748,192, as well as aliphatic di-isocyanates and,

more particularly, the trimerized or the biuretic form of an aliphatic di-isocyanate, such as

hexamethylene di-isocyanate ("HDI"), and the bi-functional monomer of the tetraalkyl

xylene di-isocyanate, such as the tetramethyl xylene di-isocyanate. Cyclohexane di-

isocyanate is also to be considered a useful aliphatic isocyanate. Other useful aliphatic polyisocyanates are described in U.S. Pat. No. 4,705,814. They include aliphatic di-

isocyanates, for example, alkylene di-isocyanates with 4 to 12 carbon atoms in the

alkylene radical, such as 1,12-dodecane di-isocyanate, 1,4-tetramethylene di-isocyanate,

and 1,6-hexamethylene di-isocyanate. Also useful are cycloaliphatic di-isocyanates, such as 1,3 and 1,4-cyclohexane di-isocyanate as well as any mixture of these isomers, 1-

isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone di-isocyanate);

4,4'-,2,2'- and 2,4'-dicyclohexylmethane di-isocyanate as well as the corresponding isomer

mixtures, and the like. A wide variety of aromatic polyisocyanates may also be used to form a polymer according to the present invention, and typical aromatic polyisocyanates include p-

phenylene di-isocyanate, polymethylene polyphenylisocyanate, 2,6-toluene di-isocyanate, dianisidine di-isocyanate, bitolylene di-isocyanate, naphthalene- 1,4-di-isocyanate, bis(4-

isocyanatophenyl)methane, bis(3 -methyl-3 -iso-cyanatophenyl)methane, bis(3 -methyl-4-

isocyanatophenyl)methane, and 4,4'-diphenylpropane di-isocyanate, as well as MDI-based

quasi-prepolymers such as those available commercially as RUBINATE® 9480,

RUBINATE® 9484, and RUBINATE® 9495 from Huntsman International, LLC. Other aromatic polyisocyanates used in the practice of the invention are methylene-bridged polyphenyl polyisocyanate mixtures which have a functionality of from

about 2 to about 4. These latter isocyanate compounds are generally produced by the

phosgenation of corresponding methylene bridged polyphenyl polyamines, which are

conventionally produced by the reaction of formaldehyde and primary aromatic amines,

such as aniline, in the presence of hydrochloric acid and/or other acidic catalysts. Known processes for preparing polyamines and corresponding methylene-bridged polyphenyl

polyisocyanates therefrom are described in the literature and in many patents, for example,

U.S. Pat. Nos. 2,683,730; 2,950,263; 3,012,008; 3,344,162 and 3,362,979. Usually

methylene-bridged polyphenyl polyisocyanate mixtures contain about 20 to about 100

weight percent methylene di-phenyl-di-isocyanate isomers, with the remainder being polymethylene polyphenyl di-isocyanates having higher functionalities and higher

molecular weights. Typical of these are polyphenyl polyisocyanate mixtures containing

about 20 to about 100 weight percent di-phenyl-di-isocyanate isomers, of which about 20

to about 95 weight percent thereof is the 4,4'-isomer with the remainder being polymethylene polyphenyl polyisocyanates of higher molecular weight and functionality

that have an average functionality of from about 2.1 to about 3.5. These isocyanate

mixtures are known, commercially available materials and can be prepared by the process described in U.S. Pat. No. 3,362,979. The present invention includes the use of mixtures of isomers of isocyanates, which are produced simultaneously in a phosgenation reaction,

or any blend of two or more isocyanates (including two or more mixtures of isocyanates,

or a single isocyanate with a mixture of isocyanates) which are produced using two or

more separate phosgenations. One preferred aromatic polyisocyanate is methylene bis(4- phenylisocyanate) or "MDI". Pure MDI, quasi-prepolymers of MDI, modified pure MDI,

etc. are useful to prepare materials according to the mvention. Since pure MDI is a solid

and, thus, often inconvenient to use, liquid products based on MDI or methylene bis(4-

phenylisocyanate) are also useful herein. U.S. Pat. No. 3,394,164 describes a liquid MDI

product. More generally, uretonimine modified pure MDI is included also. This product is made by heating pure distilled MDI in the presence of a catalyst. The liquid product is a

mixture of pure MDI and modified MDI. The term organic isocyanate also includes

quasi-prepolymers of isocyanates or polyisocyanates with active hydrogen containing

materials. Any of the isocyanates mentioned above may be used as the organic isocyanate component in the present invention, either alone or in combination with other

aforementioned isocyanates.

The term "secondary polyether polyamines" when used in this specification and

the claims appended hereto means those secondary amines within the definitions of

formula:

in which Ri and R₂ are each independently selected from the group consisting of: hydrogen; an alkyl group having 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 carbon atoms, whether straight-chain or

branched; or a radical of the formula:

in which R₃ in each occurrence may be an alkyl group having any number of carbon atoms

selected from 1, 2, 3, 4, 5, or 6, straight-chain or branched; R4 in each occurrence is a straight-

chain or branched alkyl bridging group having 1, 2, 3, 4, 5, or 6 carbon atoms; Z is a hydroxy

group or alkyl group containing 1, 2, 3, 4, 5, or 6 carbon atoms, straight-chain or branched; q is any integer between 0 and 400; and wherein X is any of:

i) a hydroxy group or an alkyl group having any number of carbon

atoms selected from 1, 2, 3, 4, 5, or 6; or

R₅ R₅ / / ii) a group Rs-N- or R5-N-R7- in which R5 and R5 are each independently selected from the group consisting of: hydrogen; an alkyl group having 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 carbon

atoms, whether straight-chain or branched; or

as defined above in which Z is a hydroxy group or an alkoxy group having 1, 2, 3, 4, 5, or 6

carbon atoms, and in which R₇ is a straight-chain or branched alkylene bridging group having 1, 2, 3, 4, 5, or 6 carbon atoms; or iii) a moiety of the formula:

R16

in which Rio, Rπ, Rw, and R15 are each independently selected from the group of: hydrogen; an alkyl group having 1, 2, 3, 4, 5, or 6 carbon atoms, straight-chain or branched; the moiety

as defined above in which Z is a hydroxy or alkoxy group having 1, 2, 3, 4, 5, or 6 carbon

atoms; Rs and R₁₂ are each independently alkyl groups having 1, 2, 3, 4, 5, or 6 carbon atoms,

straight-chain or branched; R₉, Rι₃, and R₂ι are each independently selected from a straight-

chain or branched alkyl bridging linkage having 1, 2, 3, 4, 5, or 6 carbon atoms; Riβ, Rπ, Rι₈,

R19, R₂o are each independently selected from hydrogen or an alkyl group having 1, 2, 3, 4, 5, or 6 carbon atoms; d is 0 or 1; a is any integer between 0 and 100, with the proviso that when

X is a moiety of the formula given in iii) above, b and c may each independently be any integer

in the range of 0 to 390, and the sum of a+b+c is any number between 2 and 400. According

to one preferred form of the invention, such secondary polyetheramine polyamines are diamines. According to another form of the invention, such secondary polyetheramine polyamines are triamines. According to another form of the invention, the nitrogen atoms which are secondary in such secondary polyetheramine polyamines have an alkyl group

appended to them which is selected from the group consisting of: isopropyl, 2-butyl, 4-

methyl-2-pentyl, and cyclohexyl.

To provide a polyurea polymer according to the present invention, an organic

isocyanate is mixed with a secondary polyetheramine polyamine, either manually or

automatically, using conventional production equipment. Typically, during the manufacturing

process for producing polyurea polymers according to the prior art, the organic isocyanate

and polyamine components are normally kept separated from one another, such as by being contained in separate containers, until being mixed at the time of use. The

polyamine is typically a blend of amines, pigments and other additives, and is sometimes

referred to by those skilled in the art as the "resin blend". The resin blend is usually prepared in advance of the mixing of the organic isocyanate and the amines component,

and well mixed to ensure uniform dispersion of the pigments and amines, using mixing

techniques which are known to those skilled in the art. According to one preferred form of the invention, secondary polyetheramine

polyamines are included in the resin blend. The secondary polyether polyamines may be used in place of primary polyetheramines of the prior art in an established formulation, on

a mole-equivalent basis (based on active hydrogen content), or as a blend with primary

polyetheramines, polyetheramine polyamines, other known amines, other known

polyamines, and any mixture of two or more of the foregoing. Thus, the amine

component of a polyurea formed in accordance with the present invention includes any amine from which a polyurea may be prepared which has an active hydrogen atom

attached to a nitrogen atom in its molecular structure. For purposes of this specification and the appended claims, the words "active hydrogen atom" is a hydrogen atom which is

bonded to a nitrogen atom, and which hydrogen atom is capable of participating in the Zerevitinov reaction (Th. Zerevitinov, Ber. 40, 2023 (1907)) to liberate methane from

methylmagnesium iodide. In addition, chain extenders are often employed where hard

coatings are required but can be replaced in part or in whole by secondary

polyetheramines. In another embodiment, secondary polyetheramines are used to form a prepolymer

by reaction with an isocyanate. This can be accomplished by slowly adding the secondary

polyetheramine to one or more organic isocyanates with vigorous mixing to control

polymerization to a pre-selected degree. By varying the ratio of amine to isocyanate, a

range of isocyanate prepolymers can be produced having % NCO contents of nearly any value, but most preferably from about 3% to about 31% can be formed. The new

prepolymer isocyanate is subsequently contacted with a resin blend to form a polyurea

polymer. The reduction in the speed of the reaction of the secondary polyether polyamines during production of polyurea polymers according to the present invention is a key advantage which enables formation of molded articles and coatings having higher structural integrity, and

especially in the end use of coatings, in which superior tear strengths heretofore unobserved in

these coatings have been attained. Increased work time through the slower cure rate allows for smoother and glossier coatings to form, which are also aesthetically more appealing. Slower reaction rates allow for production of caulk and sealant formulations having sufficient

gel time for practical use. Longer working times will also have benefit in adhesive and sealant

applications where having more time to bring two surfaces into contact is critical to success. The attached tables provide formulations according to the present invention and

physical properties of the resulting materials. We have included comparative formulations

from the prior art to show the benefits and differences with formulations utilizing secondary

polyether polyamines. Included are three working examples of a prepolymer formed with

product XTJ-576 that would not even be possible to produce using primary polyetheramines, owing to gellation. The secondary polyether polyamines set forth in this specification are all

poly N-isopropyl-substituted analogs of what we prefer to term primary polyetheramines, and

which Huntsman has produced and sold for many years.

Experimental As previously mentioned, the present invention relates to the formation of polyurea polymers, which requires the mixing of an isocyanate component ("A" component) and an

arrώio compound ("B" component), which amino compound, according to the invention, is

preferably a secondary polyether polyamine within the definitions above. The (A) component and (B) component of a polyurea polymer produced

according the invention are combined or mixed under high pressure. It is most preferred

that they are impingement-mixed directly in the high-pressure equipment, such as, for

example, a GUSMER® H-V proportioner (or a GUSMER® H20/35) fitted with a

GUSMER® Model GX-7 spray gun, where open-mold work or coating is desired. The

ratios of these components are adjusted such that they are processed at a 1 : 1 volume ratio at an index between 0.9 and 1.20. These systems can be processed within a pressure

range of 1000-3500 psi and a temperature range of 120-180°F with preferred processing

conditions including pressures between 1500-2500 psi and temperature of 140-170°F. Thus, the useful temperature range at which a flexible polyurea may be prepared

according to the invention is any temperature between 120-180° F. The useful pressure range

at which a polyurea may be prepared according to the invention is any pressure between 1000-

3500 psi. However, one of ordinary skill recognizes that temperatures and pressures outside these ranges are also useful; thus the present invention is not necessarily limited to being

practiced within these parameters.

For the preparation of sprayed samples according to the invention described in the

tables which follow, a GUSMER® Marksman (or H20/35) proportioning unit (plural

component) was used, fitted with a GUSMER® GX-7-400 spray gun. The equipment

was set so as to process each example at an isocyanate to resin blend volume ratio of

1.00. Spray processing pressure was maintained at 1500 psi to 2500 psi on both the

isocyanate and resin blend components. Block heat, as well as hose heat, was set at

160°F.

In the tables which follow, product XTJ-576 is di-isopropyl substituted

JEFFAMINE® D-2000; product XTJ- 584 is di-isopropyl substituted JEFFAMTNE® D-230;

product XTJ-585 is di-isopropyl substituted JEFFAMINE® D-400; product XTJ-586 is tri-

isopropyl substituted JEFFAMINE® T-403; and the product designated as IPDI is isophorone

dϋsocyanate. Throughout this specification various test results are set forth, and the following test

methods were employed in each occurrence of the following herein:

depend upon the method of preparing the polyurea polymers. For the spray method, a

vertical surface is used as a target, which is typically a piece of cardboard or other

disposable material. The spray gun is triggered to dispense polyurea onto the cardboard at the same time as the stop watch is started. Spray is continued until sufficient material has

built up to begin running downward. This is usually less than 2 seconds. "Gel Time" is

the elapsed time from the start of the watch until the polyurea material is no longer

running down the vertical surface, i.e. the polyurea has gelled to the point that it no longer flows under gravity. "Tack Free" is the time elapsed when the polyurea surface is no longer sticky when touched by a gloved finger with light pressure.

For the static mix method, because static mix samples are normally dispensed into

a horizontal mold, and therefore don't run, a different measurement is used and called

"String gel" rather than just "Gel". The stopwatch is started when the polyurea is begun to be dispensed into the mold. The polyurea surface in the area first coated is then

touched lightly with a wooden tongue depressor and then lifted vertically. The test area

must be from the first material because as many as 10-20 seconds can pass from the start

to the end of dispensing of the polyurea into the mold. In the early stages of cure, the polyurea will stick to the depressor and rise up with the vertical motion pulling a "string"

which eventually breaks loose. The touch and lift procedure is repeated until such time as

the polyurea surface no longer pulls vertically with the tongue depressor. The surface can

still be tacky and soft at this point. "Tack Free" is the time elapsed at which point the

polyurea surface is no longer sticky when touched by a gloved finger with light pressure. Also, light pressure with a gloved finger should not create a "fingerprint" or depression in the surface. Even though the surface is "tack free" it may not be strong enough at this

point to take a significant force without flowing or deforming.

Polyurea polymers were prepared by mixing an "A" component comprising an organic

isocyanate and a "B" component comprising a polyetherpolyamine according to the

proportions of ingredients specified in Table I. In Table I, DESMODUR® N-3400 is an HDI

trimer isocyanate available from Bayer Corporation of Pittsburgh, Pennsylvania (USA). The

JEFFAMLNE® trademarked amine products are available from Huntsman LLC of Houston,

Texas. In Table I below, sample 1 was produced using primary amines JEFFAMINE® D-

2000 amine, JEFFAMINE® D-400 amine, in the presence of a chain extender JEFFLINK®

754 amine. Sample 2 was produced using the experimental material XTJ-585 (secondary

amine form of JEFFAMLNE® D-400 amine having a single isopropyl group on each of the

amine nitrogen atoms) in place of the JEFFAMINE® D-400 amine. The polyurea polymers

produced using such raw materials had a tear strength of 824 pli, which is a phenomenally-high

tear strength for a polyurea polymer.

In table JJ below, sample 3 was produced using primary amines JEFFAMINE® D-2000 amine

and FFAMTNE® D-230 amine, in the presence of a chain extender JEFFLTNK® 754

amine. Sample 4 was produced using the experimental material XTJ-584 (secondary amine

form of JEFFAMINE® D-230 amine having a single isopropyl group on each of the amine

nitrogen atoms) in place of the JEFFAMINE® D-230 amine. The polyurea polymers

produced using such raw materials had a tear strength of 943 pli, which is an awesome, and

heretofore unattainable tear strength for a polyurea polymer.

In table m below, sample 5 was produced using primary amines JEFFAMINE® D-2000 amine, JEFFAMINE® D-400 amine, in the presence of a chain extender JEFFLINK® 754

amine. Sample 6 was produced using the experimental material XTJ-585 (secondary amine

form of JEFFAMINE® D-400 amine having a single isopropyl group on each of the amine

nitrogen atoms) in place of the JEFFAMINE® D-400 amine. The polyurea polymers

produced using the secondary polyether polyamine materials had a tear strength of 692 pli

comp, compared to that produced using the primary amine which was only 457, thus illustrating again the unusually-high and unexpected tear strength in polyurea materials

manufactured using secondary polyether polyamines.

variety of polyurea polymers. In this table IN, the crosslinlcer material CLEARLINK® 1000 amine (originally a UOP product) is available from Dorf-Ketal company of India. As can be seen from table IN, sample 7 which was prepared using a primary amine was too reactive to provide acceptable spray coatings. All of the spray coatings of examples 8, 9, 10, and 11 which were prepared using secondary polyether polyamines had tear strengths which are higher than the high end of the range of tear strengths of normal polyurea polymers.

Polyurea polymers produced according to the present invention using secondary polyethe olyamines are suitable for a wide range of end uses, including without limitation, the following: coatings for concrete, such as bridges, bridge pylons, bridge decks, waterproofing layers, tunnels, manholes, secondary containment, skid resistant layers, flooring, garages, aircraft hangars, sewer rehabilitation, water pipes, concrete pipes; coatings for metals, including masking layer for etching process, corrosion protection, ship hulls, ship decks, aircraft carrier decks, submarines, other military vehicles, helicopter rotor blades, bridges, structural members, playgrounds, automotive, truck-bed liners, under-carriage, outer body, rail-road cars and hoppers, trailers, flat bed trucks, 18 wheelers, large dirt moving equipment, rollers, aerospace, tank coatings (inside and out), pipe coating (inside and out); coatings for other substrates such as fiberglass boats, pavement marking, concrete marking, decorative/protective layer over various substrates for movie sets, amusement parks, parade floats, paint-ball props, electronics encapsulation, roofing topcoat for various substrates; coatings for polystyrene, wax, ice, or other media used in prototyping; manufacture of molded articles, such as reaction injection molded and products made using other molding techniques, prototype parts, shoe components, golf balls, decorative parts, automotive parts, bumpers, hubcaps; polyurea foam for sound insulation; thermal insulation; shock absorption; and other end use applications where polyurethane foam is known to be useful in the various arts; caulks for concrete floors and other architectural applications in which a sealant is employed, adhesives for bonding two components in a wide variety of substrates and applications where adhesives are normally employed; and sealants for a wide variety of non-architectural applications, such as on board of sea-going vessels. Consideration must be given to the fact that although this invention has been described and disclosed in relation to certain preferred embodiments, obvious equivalent modifications and alterations thereof will become apparent to one of ordinary skill in this

art upon reading and understanding this specification and the claims appended hereto.

The present disclosure includes the subject matter defined by any combination of any one of the various claims appended hereto with any one or more of the remaining claims,

including the incorporation of the features and/or limitations of any dependent claim,

singly or in combination with features and/or limitations of any one or more of the other

dependent claims, with features and/or limitations of any one or more of the independent claims, with the remaining dependent claims in their original text being read and applied to

any independent claim so modified. This also includes combination of the features and/or

limitations of one or more of the independent claims with the features and/or limitations

of another independent claim to arrive at a modified independent claim, with the

remaining dependent claims in their original text being read and applied to any independent claim so modified. Accordingly, the presently disclosed invention is intended

to cover all such modifications and alterations, and is limited only by the scope of the

claims which follow, in view of the foregoing and other contents of this specification.