NO163600B - REINFORCED FLUORPOLYMER COMPOSITION MATERIAL. - Google Patents

Abstract

A novel composite comprises a substrate having a coating matrix including an initial layer of a perfluoropolymer and an overcoat comprising a fluoroelastomer, a fluoroplastic, a fluoroelastomer/fluoroplastic blend, or a combination thereof. The perfluoropolymer in the initial layer may be a perfluoroplastic, a perfluoroelastomer, or blends thereof. In a separate embodiment, the novel composite includes a substrate coated solely with one or more layers of perfluoroelastomer alone or as a blend with a perfluoroplastic. Where the substrate is not susceptible to hydrogen fluoride corrosion, the composite may include solely one or more layers of a blend of a fluoroelastomer and a hydrogen-containing perfluoroplastic. Cross-linking accelerators may be used to cross-link one or more of the resins contained in the coating layers. Each composite may be topcoated with the layer or layers of a fluoroplastic, fluoroelastomer, and/or a blend thereof. The composite is flexible, exhibits good matrix cohesion and possesses substantial adhesion of the matrix to the material acting as the reinforcement or substrate. A method for making such a composite comprises the unique deployment of a perfluoropolymer directly onto the substrate in a relatively small amount sufficient to protect the substrate from chemical corrosion without impairing flexibility, followed by the application of the overcoat layer.

Description

The present invention relates to new and usable fluoropolymer composite materials which include coated substrates.

More particularly, the invention relates to a new fluoroelastomer/fluoroplastic matrix which can be used as a coating in the production of reinforced, woven composite materials which are flexible,

has good matrix integrity and has good addition or bonding to the underlying substrate. The present invention includes composite materials which also have exceptionally good chemical resistance, especially at elevated temperatures and in humid environments. In the production of such composite materials, the fluoroplastic materials' very favorable chemical resistance at high temperature is combined with. the desirable mechanical properties of the fluoroelastomers in such a way that a desirable fabric-like flexibility or pliability is maintained.

Perhaps the most well-known subgroup of fluoropolymers is

the substances often referred to as "perfluoroplastics" which generally have excellent electrical properties and physical properties, such as low coefficient of friction, low free surface energy (i.e. that it does not wet many organic liquids, and has a very high degree of hydrophobicity. Fluoroplastics, and since in particular perfluoroplastics (e.g. difluoroplastics which do not contain hydrogen), such as polytetrafluoroethylene (PTFE), fluorine (ethylene-propylene) copolymer (FEP) and copolymers of tetrafluoroethylene and perfluoropropyl vinyl ether (PFA) have resistance to a number of different chemicals, even at elevated temperature, and this makes them particularly advantageous for a number of industrial purposes and for the manufacture of various types of household articles. However, because these fluoroplastics have a partially crystalline nature, they have a rigid

heat or lack of flexibility which impairs the application of the above desirable properties. This drawback is. spec-

elt noticeable in reinforced composite materials, where it

a certain degree of flexibility or elasticity is required.

The large group of fluoropolymers also includes substances called "fluoroelastomers" which are not only elastomeric, but also, albeit to a lesser extent, have the aforementioned physical and electrical properties found in fluoroplastics. Fluoroelastomers, including perfluoroelastomers, have

the low flexural modulus and flexibility that the fluoroplastics lack. However, the hydrogen-containing fluoroelastomers do not have other advantageous physical properties found in fluoropolymers within such a wide temperature range and to such a high degree, e.g. which is found in perfluoroplastics. In other words, perfluoroplastics have better properties within a wider temperature range. The fluoroelastomers which also contain hydrogen (i.e. which are partially fluorinated) generally break down faster at higher temperatures,

and this results not only in loss of physical integrity and strength, but also in the formation of hydrofluoric acid. As is well known, hydrofluoric acid is very corrosive to most materials, and this also includes those that are normally used as reinforcing substrates for textile composite material, especially fiberglass substrates. Consequently, if hydrogen-containing fluoroelastomer composites are used in high-temperature environments, this requires relatively frequent replacements. Even with these disadvantages, however, fluoroelastomers containing hydrogen have been used for a number of different commercial purposes, where a lower flexural modulus is required than what is found in the stiffer fluoroplastics.

In connection with this, attempts have been made to use reinforced fluoroelastomer composite materials, where it has been desirable to have good hot chemical properties as well as mechanical properties, e.g. low modulus, at higher temperatures. One such purpose has been high-temperature-r

expansion joints connecting large pipe sections, e.g.

in connection with larger power plants. Such pipe sections were formerly joined by means of metal bellows, which, although chemically and thermally very safe, have minimal thermomechanical shock properties under normal operating conditions, and this may include temperatures of up to 288°C, or even up to 343° C. In an attempt to improve the mechanical properties of such metal expansion joints, flexibility is desirable in an industrial fabric, and fabric composite materials coated with fluoroelastomer-based rubber compounds have been used for this purpose.

Such fabric composite materials have used various reinforcing materials, such as fiberglass fabrics, coated with a matrix containing a fluoroelastomer composition based on copolymers of hexafluoropropylene (HFP) and vinylidene fluoride (V^) or terpolymers, and this includes HFP ,

VF2 and tetrafluoroethylene. All the fluoroelastomer materials used have contained at least some hydrogen, and therefore all have the disadvantage associated with the release of hydrofluoric acid. In order for previously known fluoropolymer composite materials to be used at high temperatures where there is a risk of chemical corrosion, it was common to incorporate a relatively thick matrix of the fluoroelastomer-based rubber, thereby increasing the stiffness of the material and intensifying the problems that arise from formation of hydrofluoric acid and subsequent embrittlement. In an attempt to avoid these problems, composite materials have been used where hydrogen-containing fluoroelastomer compounds are used which are reinforced with acid-resistant alloys, such as INCONEL, or high-temperature synthetic substances, etc. such as NOMEX and KEVLAR. However, none of these composite materials have the desired combination of good thermo-chemical resistance while having acceptable matrix integrity.

Even when using almost chemically inert substrates,

such as PTFE, and these have been coated with fluoropolymers, as described by Westley in US-PS 3,513,064, it has only been possible to manufacture the resulting composite materials by using highly specific coating materials due to the process conditions , so that the composite materials produced have properties that have a limited area of application. In the hope of achieving an improved balance in the fluoropolymer properties, attempts have previously been made to combine the respective good properties of fluoroplastic and fluoroelastomer materials in the production of coated substances. However, such attempts have only produced mixtures which either have the combined disadvantages of all components, or have reduced, good properties, especially at higher temperatures, e.g. over approx. 260°C. A typical example of these earlier attempts is set forth in US-PS 3,019,206 to Robb.

Although perfluoropolymers, whether thermoplastic or elastomeric, have excellent thermochemical stability, it is difficult to form durable bonds between them and other materials due to their low surface free energy and chemical inertness. This difficulty is usually avoided by providing a rough surface to promote a mechanical addition, e.g. by using inorganic fillers or ground or rough surfaces. Specific surface treatments, e.g. based on chemical etching have also been used. However, none of these types of techniques have resulted in bonds that are particularly strong or durable under various environmental stresses, e.g. by ultraviolet light or heat-induced oxidation.

It is therefore a purpose of the present invention

to provide a fluoropolymer composite material comprising a substrate coated with a fluoroelastomer/fluoroplastic matrix. The present composite material is flexible, has good cohesion in the matrix and there is good attachment between the matrix and the material that acts

as the reinforcing element or as the substrate in the material, while having the low stiffness associated with a fluoroelastomer, and this combined, when desired, with the superior high-temperature properties of fluoroplastics. It is also an aim of the present invention to provide a fluoropolymer composite material which is relatively light, but strong, and which both chemically and thermally has superior properties, especially at elevated temperatures and under moist conditions, while avoiding the polymer degradation problems that have hitherto has been associated with composite materials where one has had a coating matrix based on a hydrogen-containing fluoroelastomer.

It is also a purpose of the present invention to provide a fluoropolymer composite material with excellent thermochemical properties for use as a lining in chemical containers, expansion joints and for various rescue devices, such as escape caps, life jackets, rescue slides for aircraft as well as chemical protective clothing .

Furthermore, there is another purpose of the present invention

to provide a composite material that has the advantages of both perfluoroplastics and fluoroelastomers that can be used for the production of excellent flexible constructions, and this also includes multi-layered, flexible composite materials, as well as composite materials with a single coated surface.

The invention provides a grading of fluoropolymer layers to form a coating matrix for application to a substrate during the manufacture of a new composite material. Said fluoropolymer layer includes perfluoropolymers as well as hydrogen-containing fluoropolymer components which are used in a new and unique way, so that the desired, advantageous properties of different fluoropolymer components are combined. The hydrogen-containing fluoropolymer components include fluoroplastics, fluoroelastomers and mixtures of fluoroelastomers and fluoroplastics. The perfluoropolymer component or components are first applied and provide a hydrogen-free interface, so that the substrate material, which could otherwise be exposed to corrosive effects of hydrogen fluoride that might have to be developed by other hydrogen-containing fluoropolymer components, is protected against such effects while maintaining the basic flexibility of the substrate. A fluoroplastic component can also include a top layer or a surface layer or a part thereof, when a thermoplastic instead of an elastomer is desired. Hydrogen-containing fluoroelastomer components can be used inside the coating matrix, so that they are isolated by means of the perfluoropolymer layer from a substrate that may be exposed to HF corrosion, while at the same time they are placed so that they improve the flexibility of the resulting composite -the membrane.

When the fluoroelastomer component is used either inside or

as a top layer, the component will also function so that it improves the flexibility of the composite material, and gives the surface rubber-like properties.

According to the present invention, a composite material is provided consisting of a substrate coated with a matrix, and the matrix is characterized by the fact that it consists of:

A) a first layer of a perfluoropolymer selected from a perfluoroplastic, a perfluoroelastomer, a mixture of perfluoroplastics and perfluoroelastomers, or any combination thereof, optionally together with a lubricant; and B) an overlying layer of a fluoroelastomer, a fluoroplastic, a fluoroelastomer/fluoroplastic blend, or any combination thereof; and optionally C) an intermediate layer consisting of a fluoroelastomer situated between the first layer and the overlying layer, and a. top coating selected from a fluoroplastic, a fluoroelastomer, a fluoroplastic/fluoroelastomer blend or a combination thereof, where the substrate has optionally been treated with a coupling agent to prevent bonding.

The substrate, which is preferably a textile substrate, can be coated on a

or both surfaces with the matrix.

The perfluoroplastic is e.g. PTFE, and the perfluoroelastomer can be

KALREZ (DuPont).

The fluoroelastomer or perfluoroelastomer constitutes from 10 to 90% by weight of the mixture, preferably from 25 to 60% by weight.

The new composite materials can consist of a substrate that is only coated with one or more layers of the perfluoroelastomer alone or as a mixture with a perfluoroplastic material. When the substrate is not exposed to HF corrosion, the composite material can include only one or more layers of a mixture of a hydrogen-containing fluoroelastomer and a perfluoroplastic material.

In other embodiments, the basic coating matrix will consist of the elements A and B as indicated above, with a number of perfluoropolymer coating layers all so positioned. that. one achieves the desired properties. In those embodiments where a substrate is coated with a matrix only on one side, the substrate can be attached to other substrates on the other side. Each composite material according to the present invention can be top coated with one or more layers of a fluoroelastomer, fluoroplastic and/or a mixture of a fluoroplastic or a fluoroelastomer which may differ in composition from any other top layer.

In addition, relatively small amounts of cross-linking accelerators, such as triallyl isocyanurate, triallyl imidazole etc. is used to crosslink one or more of the resins present in the coating layers, as desired, using high energy electrons or actinic irradiation.

Composite materials produced in accordance with various embodiments of the present invention are characterized by good internal matrix cohesion and attachment between the substrate and the fluoropolymer matrix. Composite materials can be produced with exceptionally good resistance to heat and/or chemical degradation, and which can withstand heat-mechanical shocks. Composite materials according to the present invention require far less coverage, i.e. redu-

increased thickness of the coatings, compared to previously known composite materials, so that tighter ■■■■ zzæssjr and/or thinner, but none the less stronger products are provided.

Any suitable reinforcing material capable of withstanding the process temperatures used can be used as a substrate. Examples include i.a. glass, fiberglass, ceramics, graphite (carbon), PBI (polybenimidazole), PTFE, polyaramids, such as KEVLAR and NOMEX, metal meshes, polyolefins, such as TYVEX, polyesters, such as REEWAY, polyamides, polyimides, novoloid-phenolic fibers, thermo-plasters, such as KYNAR, TEFZEL and KYNOL, polyether sulphones, polyether agents, polyether ketones, cotton, cloth and other natural as well as synthetic textiles. Substrates can also consist of a yarn, of threads, monofilaments or other fibrous materials, either as such or combined into a textile fabric, or other woven, non-woven, knotted, felted etc. materials. Depending on the nature of the substrate and the use of the composite material, the reinforced material can

easily impregnated, either first or at the same time as applying the first polymer layer, with a suitable lubricant or saturating agent, such as methylphenylsilicone oil, graphite, a highly fluorinated liquid such as FLUORLUBE or KRYTOX etc.,

and the impregnation may include a coupling agent. The lubricant or saturant performs 3 functions via the reinforced substrate: (1) as a lubricant, it protects the substrate from self-wear by maintaining the mobility of the reinforced elements; (2) as a saturating agent, i.e. that it prevents too strong penetration of the first polymer layer into the substrate, which could reduce the flexibility; and

(3) in a finished product, the agent will remain in the substrate and prevent the penetration of moisture or other degrading chemicals through the substrate. The lubricant or saturant can either be applied separately with a first pass or in combination with the first application of a perfluoropolymer component.

The present invention also includes a new method for the production of the present composite materials, in which the various coating layers comprising the matrix as described above are deposited in a unique way, especially in such a way that the harmful effects of any hydrogen fluoride which had to be developed from hydrogen-containing fluoroelastomers or fluoroplastics, while maintaining good flexibility. As such, the method results in the production of an improved product with a low modulus with regard to stiffness and good chemical resistance within a large temperature range, whereby the products can be used for a wide range of different purposes.

The first layer, described as element A above, is applied so as to obtain minimal stiffness in the final material,

and to obtain maximum attachment of the matrix to the substrate. The application of layer A can be carried out in one or more passes, and preferably so that any openings in the substrate will essentially remain open, so that you get good flexibility, especially in cases where any additional top layers such as element B are to be applied. IN

the cases where a substrate is used which is a composite fibrous material, then the first covering layer can be applied to the elements of the material (e.g. threads or yarn) before it is put together, e.g. by dip coating, impregnation or extrusion coating. Such materials can then be put together, e.g. by weaving, knotting, felting etc.

In the embodiments which include both a hydrogen-containing fluoropolymer and a chemically exposed substrate, e.g. which is exposed to HF corrosion, then the first perfluorinated layer must be sufficient to protect the reinforcing substrate, and especially a fiberglass substrate,

potassium such as hydrogen fluoride comes from. Depending on the substrate, additional thin layers of perfluoropolymer may be used to ensure that the reinforcing element has a sufficient protective layer. With the right choice and application of coating layers, the penetration of aggressive chemicals, such as hydrogen fluoride, can be prevented with the help of the protective hydrogen-free perfluoropolymer interface while maintaining the flexibility of the composite material.

The first layer is then covered with one or more layers

a fluoroplastic, fluoroelastomer, a mixture of a fluoroelastomer and fluoroplastic or a combination of these, as described as element B above. Preferably, this part of the matrix should include one or more layers

of a mixture containing the fluoroelastomer in such quantities that a suitable balance of fluoropolymer properties is obtained in the composite material. When you e.g. want a composite material with pronounced elastomer properties, then increasing amounts of fluoroelastomers can be used in the mixture. It has been found that by a combination of layers A and B, especially by using a mixture of a fluoroelastomer and fluoroplastic according to the present invention, sufficient internal cohesion in the matrix can be achieved as well as an attachment of the matrix to the substrate simply by using heat, and without any physical or chemical treatment of the substrate or the individual matrix layers and without using compounds that promote adhesion between matrix and substrate. By using the present matrix, and especially by using layers facing each other and the substrate according to the present invention, it is possible to maintain a sufficient degree of adhesion while having the

desirable flexibility and the desirable properties of the various fluoropolymer components in the matrix. This also makes it possible to choose one or more top layers that have properties both from a fluoroplastic or a fluoroelastomer or combinations of these, as desired.

As soon as the first layer and any covering layer have been deposited, you can choose a top layer, either of a fluoroplastic or any additional fluoroelastomer layers. A surface layer of a perfluoroplastic, such as PTFE, or a perfluoroelastomer, such as KALREZ, or the fluoropolymer mixture using the copolymer of a perfluorinated polyvinyl and which is described in US-PS 4,252,859 to Concannon et al., provides better thermal properties and resistance to chemical corrosion, than e.g. the embodiment where one has a hydrogen-containing fluoroelastomer or mixtures containing a fluoroelastomer.

Application of layers to the matrix can be carried out by dip coating from an aqueous dispersion, but any other known method can also be used, e.g. spraying, dipping or pour-on coating, either from aqueous dispersions or solvent dispersions, calendering, lamination, etc., thereby producing a coating in a well-known manner.

The term "fluoroplastics" as used herein includes both hydrogen-containing fluoroplastics and hydrogen-free perfluoroplastics unless otherwise specified. Fluoroplastic substances essentially mean polymers with a general paraffinic structure, and where some or all hydrogen atoms have been replaced by fluorine atoms, and include e.g. polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP) copolymer, perfluoroalkoxy (PFA) resin, polychlorotrifluoroethylene (FCTFE)

and its copolymers with TFE or (VF),,, ethylene chlorotrifluoroethylene (ECTFE) copolymer and its modifications, ethylene-tetrafluoroethylene (ETFE) copolymer and its modifications, polyvinylidene fluoride (PVDF), and polyvinyl fluoride (PFV).

Similarly, the term "fluoroelastomer" includes both hydrogen-containing fluoroelastomers as well as hydrogen-free perfluoroelastomers unless otherwise indicated. By a fluoroelastomer is meant any polymer with elastic properties or a high degree of compliance, and which contains one or more fluorinated monomers with an ethylenic unsaturation, such as vinylidene fluoride, and possibly one or more other compounds containing an ethylenic unsaturation. The fluorinated monomer can be a perfluorinated monoolefin, e.g. hexafluoropropylene or tetrafluoroethylene, or a partially fluorinated mono-olefin which may contain other substituents, e.g. chlorine or perfluoroalkoxy, e.g. vinylidene fluoride, pentafluoropropylene, chlorotetrafluoroethyl and perfluoroalkyl vinyl ether, e.g. perfluoro (methyl vinyl ether) or (propyl vinyl ether); and the mono-olefin is preferably straight or branched with a terminal ethylenic double bond. The elastomer preferably consists of units made from fluorine-containing monomers. Such other monomers can e.g. include olefih with

a terminal ethylenic dotbelt bond, then especially ethylene and propylene. The elastomer will normally consist of carbon, hydrogen, oxygen and fluorine atoms.

Any fluoropolymer component may also contain a functional group, such as carboxyl, and sulfonic acid and salts thereof, halogen as well as reactive hydrogen on an alkyl side chain.

Preferred elastomers are copolymers (hereinafter referred to as copolymers) of vinylidene fluoride and at least one other fluorinated monomer, especially one or more hexafluoropropylene, pentafluoropropylene, tetrafluoroethylene and chlorotrifluoroethylene. Available fluoroelastomers include copolymers of vinylidene fluoride and hexafluoropropylene, and terpolymers of vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene,

which is sold by DuPont as VITON and by 3M as LUOREL <p>g by Daiken as DAIEL. Other elastomeric copolymers of vinylidene fluoride and chlorotrifluoroethylene are available from 3M as

Kel-F. You can also use AFLAS, which is a copolymer of

TFE and propylene, and which is manufactured by Asahi.

Preferred perfluoroelastomers include elastomeric copolymers of tetrafluoroethylene with perfluoroalkyl copolymers,

such as hexafluoropropylene or perfluoro (alkyl vinyl ether)

co-monomers represented by

where R 1 is a perfluoroalkyl or perfluoro(cyclooxaalkyl) group. Particularly preferred are the perfluorovinyl ethers where R^ is selected from the following: -CH^, - C^ F^,

where n = 1-4 and X = H, Na, K or F. In particular, you can use KALREZ, which is a copolymer that includes TFE and perfluoromethyl vinyl ether (PMVE).

If desired, fillers or additives can be used in a well-known manner, such as pigments, plasticizers, stabilizers, fillers, etc. in the matrix composition. E.g. can you use substances such as graphite, carbon black, titanium dioxide, aluminum oxide, aluminum oxide trihydrate, glass fibres, glass beads or microspheres, carbon fibres, r<p>ayresium oxide, silicon dioxide, asbestos, ullastonite, mica etc.

The application of the different matrix layers on the substrate according to the present invention takes place essentially by means of the method which includes the following steps: 1. If it is necessary or desirable, remove surface treatment substances from the substrate material, e.g.

in connection with woven fibreglass, by heating

the substrate or washes a woven, synthetic fabric.

2. Apply as a first layer on one or two surfaces of the substrate, a perfluoropolymer, preferably a perfluoroplastic such as PTFE or a perfluoroelastomer such as KALREZ or mixtures thereof. As mentioned above, an embodiment of the invention includes one or more layers of a perfluoroelastomer or a mixture thereof, applied to the substrate, whereby a composite material is produced. As mentioned above, a suitable saturating agent or lubricant can be used, preferably a methylphenyl silicone oil, e.g. in a mixture containing from 2 to 4 parts by weight of lubricant, the substrate is applied, either before applying the polymer or at the same time as this is applied. In cases where there is sufficient flexibility, a coupling agent can be used to improve the attachment of the matrix to the substrate. As mentioned earlier, the first layer is applied so that minimal stiffness is obtained in the composite material, and a relatively light layer can be used depending on the weight and porosity of the substrate. As mentioned above, the substrate can be coated only on one surface, while the other surface of the substrate can be attached, e.g. to another substrate material. 3. Apply one or more layers as a top layer to the first layer, a fluoroplastic, a fluoroelastomer, a mixture of a fluoroelastomer and a fluoroplastic, preferably a perfluoroplastic, e.g. PTFE or a combination thereof. When using a mixture of fluoroelastomer and a fluoroplastic, either alone or as a layer on top of a fluoroelastomer layer, the mixture should contain from 10 to 90% by weight of the fluoroelastomer component, preferably from 25 to 60% by weight. 4. If desired, one can apply a top layer either of a fluoroplastic material, and again preferably a perfluoroplastic material, such as PTFE or melt-producible copolymers of TFE or a top layer consisting of a further layer of a fluoroelastomer, preferably

v

show a perfluoroelastomer, or a mixture of a fluoroelastomer and a fluoroplastic.

5. If necessary, a surface layer can be applied

a fluoroplastic material of greater thickness by extrusion or by lamination of a melt-processable film, e.g. of PTFE, FEP or PFA, or a fluoroelastomer such as VITON, AFLAS or KALREZ.

It is also clearly an advantage that composite materials according to the present invention can be produced, if this is desired, by the so-called aqueous dispersion technique. The method can be carried out under such conditions that heat can be used to produce the desired cohesion in the matrix and attachment to the substrate. A preferred method for producing the present composite materials involves first applying a perfluoropolymer from a latex or dispersion onto a suitably prepared substrate at a temperature which leads to melting and attachment of the applied polymer. After this layer, an overlay consisting of fluoroelastomer, a fluoroplastic material or a mixture of a fluoroelastomer and a fluoroplastic material, made from a latex or dispersion mixture, is applied, and this is applied in such a way that the coating is dried, but does not overshadow the upper temperature limit of the most heat labile component. The resulting partially consolidated coating layers can then be subjected to moderate heat under pressure to further strengthen the applied layer. Calendering is an appropriate method to achieve this result. The top layer is then applied at a temperature sufficiently high to melt the component having the highest melting point, thereby producing a complete consolidation with minimal heat exposure for the most heat-labile component. A latex is often available for this purpose. Optionally, the top layer can be applied by extrusion application, calendering or by laminating polymeric components on the previously consolidated layer. Extrusion application is most advantageous when a foamed top layer is desired.

It is understood that in any embodiment according to the present invention the upper or surface layer can be applied

>m a foam to increase compressibility or to increase

-/kkelsen with low density.

the following additives may be used in the process of preparing the matrix composition: a surfactant such as an anionic active agent or a nonionic active agent, a creaming agent such as sodium or ammonium alginate; a viscosity-regulating agent or a thickening agent, such as methyl cellulose or ethyl cellulose; a wetting agent, such as a fluorinated alkyl carboxylic acid; an organic solvent, a sulfonic acid; or a film former.

The advantageous properties of composite materials according to the present invention appear in more detail and are illustrated with reference to the attached drawings, where

Fig. 1 and IA show a schematic section through woven composite materials which have been produced using several embodiments according to the present invention. Fig. 2 is an enlarged schematic section through an open woven fiberglass composite material coated according to an embodiment of the invention. Fig. 3 is a diagram showing the relationship between tensile strength and time for a composite material from example 2 at elevated temperatures in air. Fig. 4 is a diagram showing the relationship between tensile strength and time for the composite material according to example 2 in the present invention when it was immersed in 2 N sulfuric acid at its boiling point.

In fig. 1 is the previously assembled (woven) yarn 10

has first been treated with a silicone oil which is then coated with a first fluoropolymer layer 12 which completely covers both the warp 14 and the weft 16 of the yarn 10. The layer 12 is then applied to a layer 18 consisting of a mixture of a fluoroelasto-

more and a fluoroplastic. The resulting composite material can be further coated with an optional fluoroplastic or fluoroelastomer top layer 20 as shown in the drawing.

Fart. IA shows a vertical section through a woven composite material where the first coating layer 12 is applied to the yarn before it is assembled (woven) and thereby completely surrounds all the fibers in the yarn 10. Such a composite material has improved flexibility depending on the composition of made 12.

Fig. 2 shows the deposition of the different layers in a coating matrix according to an embodiment of the invention where the substrate is woven. Shown is an enlarged section of a regular woven substrate where both warp 12 and weft 16

on the yarn 10 is first coated with a light layer of lubricant (not shown) and a fluoropolymer 22. The layer 22 is deposited on

such a way that it covers and protects the yarn 10 while at the same time obtaining free and clear openings 24 in the woven substrate, whereby the overall flexibility of the composite material is not significantly weakened. The first coated substrate is then applied to an overlay 26 of a fluoroelastomer/fluoroplastic mixture according to the present invention, and which covers the yarn 10, and this includes a warp 14 and weft 16, as well as the openings 24, which when filled with a more elastic mixture 26, the resulting composite material has a lower flexural modulus.

The invention and its advantages are further illustrated by means of the following examples. In these examples, composite materials are illustrated where a number of different substrates and coating matrices according to the present invention are used. The methods used for chemical and physical testing and determination of properties for composite materials produced according to the present invention and for the control materials are stated below.

Example 1.

In accordance with a preferred embodiment of the present invention, a fiberglass substrate, Chemfab No. 15227, with a weight of 610.3 g/m 2 was heat cleaned to remove residual surface treatment. A combination of PTFE (TE-3313 manufactured by DuPont as an aqueous dispersion, 60% solids) and methylphenyl silicone oil (ET-4327 manufactured by Dow Corning as an aqueous emulsion, 35% solids) was then applied to the surface of the substrate by dipping , drying and fusing in a 2-zone coating tower with drying zone temperatures of approx. 93.3-176.7°C and a sin-sintering zone of approx. 371.1°C. The coating contained 93 parts PFTE, 7 parts methylphenyl silicone. The combination was on-

laid as a very light substrate in a weight of 169.5 g/m to avoid unwanted stiffness. Only the yarn fibers in the substrate were coated, and the openings essentially remained open.

A second layer weighing a total of 678.1 g/m 2 was applied from a mixture of VITON B fluoroelastomer (VTR-5307 from DuPont as a terpolymer latex, 60-65% solids) and PTFE (TE-3313). The layer was applied in several passes by dipping, drying and curing in a 2-zone tower with a drying temperature of 93.3-176.6°C and a sintering zone temperature of only 260°C. The mixture, designated FMK-4-10-B, consisted of 60% PTFE; and 40% thermopolymer fluoroelastomer per weight.

The material was finished by coating fabric

was calendered at a temperature of 149°C, and then dried by passing the substrate through the tower to melt or sinter the coating, and this was done at a temperature of about 371.1°C.

Example 2

As indicated in example 1, a composite material was produced from a heat-cleaned glass cladding substrate (Chemfab Style no.

122, 1085.0 g/m 2) by using the same primer composition to a weight of 1356.3-1390.2 g/m 2 and the same mixture to a weight of 1831.0-1898.8 g/m<2 >. In addition to this, a top layer of PTFE was added in several passes through TE-3313, so that the total weight of the composite material was from 2034.4 to

2

2102.2 g/m . In this example, the top layer of PTFE was applied after applying the mixture which was not calendered

in advance, by dipping, drying and curing at 310°C.

The resulting material was calendered and machined

through the tower, dried and cured in a zone at 370.1°C to melt or sinter the coating. The so-called dry-melt composite material was given a top layer of PTFE by dipping in TE-3313, then dried and then melted at 371.1°C. compo-

in kg/cm of 250.0/245.6 kg/cm 2warp to weft, bending in kg/cm of 250.4/242.2 kg/cm warp to weft, and a tear strength in kg of 104.8/133 ,9 warp and weft. The coating's addition was measured at 4.12 kg/cm and the porosity was 3.963 l/hour/m .

Four further composite materials were produced as described in example 2, using glass cladding reinforcement

end materials with lighter weight and proportionally lighter structure of the various matrix components, as shown in the following table.

These composite materials were tested as indicated in Table I below:

In addition, example 2A was tested after 9 months of use in an expansion joint in an electric power station. The material in use showed significantly less degradation than conventional joints based on a fluoroelastomer.

Examples 3-8.

Six additional composite materials were prepared as described in Examples 1 and 2, except that the fluoroelastomer/PTFE blend ratio was varied as follows:

These composite materials were tested as indicated in Table III below:

Preparation of control samples.

A control composite material A was prepared using Chemfab Style 15227 glass cloth (610.3 g/m 2 ) and was heat cleaned to remove residual surface treatment. This substrate was then o coated to a weight of o 1390.2 g/m 2 with a mixture of (a) a fluoroelastomer (L-6517 is manufactured by 3M and is a copolymer latex, 55% solids) and (b)

PTFE (Teflon 30B from DuPont) in a weight ratio of 80/20

(PTFE/fluoroelastomer) per weight. The coating was applied in several passes at a process temperature of 204.4°C. Control B is the same as control A, except that it is dry-melted as composite materials according to the present invention. Control C is the same as control B, with a fused top layer of PTFE (TE-3313) in an amount corresponding to approx. 42.4 g/m .

Results of physical tests on these materials are given in table IV.

Examples 9 A-C

A comparison was made using samples of composite materials prepared as described in Examples 1 and 2, but using different commercially available fluoroelastomers. The first composite material 9A was produced essentially as the material from Example 6. Composite material 9B was produced in essentially the same way, but using the L-6517 fluoroelastomer (a 3M copolymer latex, 55% solids). In a similar manner, the composite material 9C was prepared by again using another 3M fluoroelastomer (L-6546, a terpolymer latex containing 60% solids) in place of the DuPont VTR .... 5307..

The results of physical tests carried out with these composite materials are given in Table V.

Examples 10 A-C

Composite material 10A was prepared using Style 15227 glass cloth (610.3 g/m 2 ) which was first heat cleaned to remove residual surface treatment. A combination of PTFE (TE 3313) and methylphenyl silicone oil (Dow Corning) was then applied to the substrate surface in an amount of 169.5 g/m 2. A second layer of a mixture of the 3M fluoroelastomer (L-6517) and FEP resin (DuPont TE-9503) aqueous dispersion, 55% solids) in a ratio of 40/60 was then applied in several passes in an amount of about 271.3 kg/cm 2 . The composite material was then applied a top layer of PTFE (TE 3313) in an amount of 169.5 g/m 2 , whereby a composite material weight of 1220.7 g/m 2 was obtained. Another composite material 10B was prepared by using a 40/ 60 blend of the 3M L-6546 fluoroelastomer and DuPont-9503, and a third composite material was similarly prepared using a 40/60 blend of DuPont VTR 5307 and TE-9503.

Results of physical tests carried out with these composite materials are given in Table VI:

Examples 11 A-C

Composite materials were produced with reinforcing elements other than glass, as indicated in Table VII. The composite materials 11A, 11B and 11C were prepared as described in Example 2, using a three-component matrix consisting of a PTFE-silicone oil primer, an intermediate compound component and a top layer of PTFE.

Composite material prepared as described in Example 11 was tested, and the results are given below. Hot air and hot acid treatment, test results. % tensile strength (in warp) retain after treatment.

Examples 12 A-D

Four additional composite materials were prepared using the procedure of Examples 1 and 2, but the lubricant/saturant was either (1) an ET-4327 methyl-phenyl silicone oil emulsion applied in FMK-4-10-A (Chemfab internal designation for the mixture of TE-3313 (DuPont) and ET-4327 (Dow Corning Corp.) containing about 93 wt% PTFE and 7 wt% silicone oil diluted with water to a specific gravity of 1.32); (2) ET-4327 methylphenyl silicone in an aqueous solution (a mixture of one volume of ET-4327 methyl-phenyl silicone oil emulsion manufactured by Dow Corning, and 8 volumes of pure water); (3) ET-4327 methyl-phenyl silicone in an aqueous solution, one part by volume:4 parts by volume pure water; or (4) a mixture of 9 parts by weight ET-4327 diluted with water 1:8 per volume) and 1 part by weight of AQUADAG E colloidal graphite dispersion. With the exception of the material which had a first dip in the aforementioned FMK-4-10-A, a new layer of TE-3313 (specific density 1.35 g/cm"^) was applied after the application of the lubricant. The four composite the materials were then made complete as described in Examples 1 and 2.

The resulting materials were tested for weight, thickness, tensile strength, tear strength and flexural strength, and coating attachment and MIT flexural strength. The results are shown in Table IX.

Example 13.

Composite materials were prepared using TE-5489 (low crystalline, pliable, perfluorinated TFE copolymer manufactured by DuPont) resin dispersion in the following manner.

In Example 13, Chemfab Style 116 glass was heat cleaned and given four full strength dips of TE-5489

(33% solids, specific density of 1.23 g/cm 3, 9.5

eps in viscosity). The heat cleaned substrate which had a weight of 103.1 g/m <2> absorbed a total of 23.7 g/m <2> of said TE-5489. Microscopic examination of the product revealed a coating which was elastic, without cracks and without visible marks, and which encapsulated the yarn and was well greased thereto.

Example 14.

Example 14 was prepared by pouring 25 g of TE-5489 onto a 7.62' x 12.7 cm piece of hot-cleaned and silicone-treated 15227 glass cloth in a trough. The water was dried away in an air circulating oven, 75°C, and the resulting fabric saturated with the dried polymer was held between plates in a press for approx. 10 minutes at 204.4°C. The resulting composite material was very pliable and pliable, and the coating was. strong and elastic, and was resistant to scratching.

Example 15 A-C

Examples 15 A and B were prepared in the following manner. After heat cleaning, 2 lengths of Chemfab Style 129 were glazed

(210.2 g/m 2 ) (ECD 225 1/3, 38 x 40) coated by multiple passes in the dispersion of a 50:50 (wt) mixture of TE-5489 and a commercially available perfluorinated resin dispersion. After the last application, the product was dried. Example 15A was passed 7 times through such a mixture, prepared with TE-3313, which resulted in a composite material with a weight of 323.5 g/m 2. Example 15B was passed 6 times through a mixture prepared from TE- 9503 heat concentrated in the laboratory to a solids content of 63%, and this resulted in a product weighing 313.6 g/m 2 . These samples were tested as shown below.

Example 15C was prepared in the following manner. After water cleaning, Chemfab Style 15227 glass cloth (610.3 g/m<2>) (ECB 150 4/3, 18 x 19) was treated with silicone oil by dipping the cloth in ET-4327 diluted 1:8 per volume of water, followed

of drying and curing at 343.3°C. A first coat of a 50:50 (w/w) blend of TE-3313 and TE-5489 was then applied by dipping, scraping with smooth rods, drying and curing

at 260°C. This first layer weighed 172.9 g/m<2>. A top-

layers of FMK-4-10-B were then applied in 5 successive semi-melt passes, and a total of 600.2 g/m 2 was applied. A top layer of 33.9 g/m 2 of PTFE was applied in a single semi-melt pass through TE-3313 with a density of 1.30. The material was then calendered, and finally melted in a single dry melt pass at 382.2°C.

The finished composite material was softer than the samples

1 and 2. The coating, although it is not as glossy and feels more compressible than the coatings in examples 1 and 2, is otherwise very durable when the material was subjected to rough treatment, such as scraping and squeezing. Renningdn's tensile strength in this material was 154.1 g/cm, while the adhesion of the coating was 1.59 g/cm.

Examples 16 A-F

Example 16A was prepared by providing Chemfab Style 100-20

woven KEVLAR fabric (approx. 16 x 16 threads per vm 2 , and a weight of 223.8 g/m 2 , yarn construction unknown), 2 coated melt dips through undiluted TE-5489 dispersion. Curing temperatures were 287.7 during both passes. The finished weight of the fabric was 301.8 g/m2.

Example 18B was prepared with the same gain as Example 16A and was given a single melt dip through TE-5489 under the same conditions as stated at the beginning

2

of Example 16A, so that the total weight was 267.9 g/m .

This was followed by three so-called semi-melting dips, through FMK-4-10-B where the material between each pass was cleaned

using a wiper, and where the curing temperature was 260°C, and this raised the total weight to 386.5, 457.7 and 576.4 g/cm 2 respectively. The material was finally cured by a pass at 371°C .

Example 16C was prepared with the same reinforcing material as Examples 16A and 16B, but in Example 16C the first coating consisted of a mixture of 50% by weight PTFE from TE-3313 and 50% by weight polymer from TE-5489 applied by a so-called melting dip at 287.7°C. The total weight of reinforcing material and thus the first layer was 284.8 g/m 2 . As a top layer, three dips with FMK-4-10-

B which was dry melted substantially as prepared in Example 16 B, giving a finished product whose weight was 569.6 g/m 2 . The three products were tested as shown in the following table.

A reinforcement for Examples 16D, E and F was prepared by heat scouring Style No. W-134 woven graphite fabric

(196.7 g/m 2 , approx. 12 x 12 threads per cm 2 manufactured by Fiberite Corporation) when cured at 320°C. Example 16D was then prepared by giving the reinforcement two so-called melting dips through a TE-5489 dispersion at 287.8°C. The finished weft was 281.4 g/m2.

In the preparation of the material of Example 16E, the heat-cleaned graphite was given a silicone treatment by dipping the reinforced material through. ET-4327 diluted 1:8 per volume with water followed by drying and curing at 260°C. This was followed by one dipping through TE-5489 and curing at 287.7°C, giving the 203.4 g/m 2 silicone-treated fabric a total weight of 250.9 g/m 2 . Three additional coated, half -fused layers of FMK-4-10-B were applied and followed by curing at 260°C, bringing the weight to 403.5, 461.1 and 532.3

2

g/m respectively after each review. Finally, a cure was carried out at 371.1°C.

Example 16F was prepared in essentially the same way

as Example 16E, using a silicone treated reinforcing material, but with a 50:50 blend of TE-3313

and TE-5489 instead of TE-5489 as the first layer. The weight after this step was 264.5 g/m 2 . Three brushed, semi-melting layers of FMK-4-10-B were then applied and dry-melted as described in Example 16E, giving a final weight of 525.6 g/m m 2. The three products were tested as shown in the following table.

The examples 17 A- M

Several composite materials incorporating a KALREZ latex from DuPont and identified as 34045-133 were produced by a lamination process which involves evaporating the dispersion to dryness in order to obtain a crust-like material, after which this is pressed into a film in a plate press and laminates the film to the substrate, also in a plate press. Example 17A was prepared by heat cleaning Style 15227 glass and giving the glass a silicone treatment by dipping through an ET-4327 bath diluted 1:8 per volume with water followed by drying and curing. The treated substrate was then dipped through a KALREZ dispersion, not brushed off, and then cured at 260°C. The resulting composite material weighed 705.3 g; /m 2.

Example 17B was prepared by giving a portion of the coated fabric from Example 17A four semi-melting layers applied by passing through TE-3313, treated to a viscosity of approx. 150 eps, at the same time that it was brushed with rods, the distance of which was 0.1 mm. The resulting material with a weight of 1327.4 g[m 2 was pressed in a plate press for 1 minute at approx. 91.4 kg/erri<o>' while the plate temperature was 162.8°C. The coated surface was protected with release sheets of Chemfab 100-10 TCGF (PTFE coated glass fabric) during pressing. The material was then cured for 20 minutes in an air circulating oven at 273.9°C to remove residual surfactant. The material was then returned to the press, protected by a clean aluminum foil on both sides and sintered by pressing with a minimum pressure (less than 1.1 kg/cm 2 ) while the plates were heated to 382.2°C for 5 minutes. The resulting material weighed

2

about. 1203.7 g/m .

Example 17C was prepared in a portion of the coated fabric from Example 17A five coated passes through undiluted VTR-5307 fluoroelastomer latex. After each review, the material was dried and hardened at approx. 148.9-232.2°C. The material was then cured at 274°C in an air circulating

oven for 20 minutes to remove residual surfactant. The final weight of the material was 1091.8 g/m 2.

Example 17D was prepared by passing a portion of the coated fabric from Example 17A three fusing coated passes through rods spaced 0.1 mm and using an FMK-4-10-B dispersion, all at a pass rate of 25 cm/minute. The material, which at this point weighed 1115.5 g/m 2 , was then cured at 274°C in an air circulation

end furnace and melted in a plate press at a pressure of less than 1.1 kg/cm with a plate temperature of 382°C for 5 minutes,

between sheets of pure aluminum foil.

In Example 17E, a KALREZ crust was prepared by evaporating a certain amount of KALREZ dispersion to dryness in an air circulating oven at 23.8 - 29.4°C. 10 g of the crust was placed between approx. 18" x 18" pieces of aluminum foil, treated with a silicone release compound (SPRITS SILICONE MOLD RELEASE, sold by Sprits of Melville, New York) on one side, and a corresponding sheet of the same size of silicone resin coated glass fabric (available as SRC-5 from Oaks Industries, Inc., Hoosick Falls, New York) on the other side. The material was placed between smooth plates of stainless steel with a thickness of 0.31

cm and pressed for 5 minutes at a pressure of 80 tonnes on the plates at 288°C, after which the press was cooled under pressure. The result was a circular piece of KALREZ film with a diameter of 20.3 to 25.4 cm, and with a varying thickness from 0.013 to 0.020 cm.

The film was then folded over an edge of part of the fabric

from example 17A, so that approx. semicircular areas of file-

but was on either side of the material from Example 17A. The entire material was then placed in a press between glass

cloth that served as fusion pads,. in order to. press the film into the irregularities of the reinforcing sub-

layer. Aluminum foil treated with a silicone mold release agent was placed between the films and the compression pads. Stainless plates were used. The laminate was pressed for 5 minutes at 287.8°C, applying a force of 10 tons to the plates (approx. 28.1-35.2 kg/cm 2 on the semi-circular composite

the material whose diameter was 25.4 cm). The material was then cooled under pressure.

The foil was easily torn away, so that a semi-circular, laminated composite material was obtained surrounded by a lightly coated reinforcing material. This material was again placed in a press between cast release treated aluminum foil for 5 minutes with 5 tons of force on the plates at 176.7 to smooth out the fabric impression coming through the foil from the compression pads. The fully smooth laminate was 0.071 to 0.074 cm thick near the center, and 0.066 to 0.069 cm near the edges. Under the microscope, no cavity was visible, whether one looked through the fabric surface from the top, or along the cut edges. Visually, the material was indistinguishable from the dip coated material except for a complete lack of bubbles and holes and craters.

In a similar way, laminated composite materials were produced in the same way as in example 17E, using as substrate the material from examples 17D, 17C and 17B. These were designated examples 17G, 17H and 17J respectively.

For ease of comparison, the compositions of Examples 17A-E and G, H and J are set forth in the following table. Example 17K was prepared by placing a film prepared from Kalrez latex as described in connection with the preparation of Example 17E, on one side of a piece of Chemfab Style 129 glass fabric which had previously been heat cleaned. The layer was protected on both sides by aluminum foil and placed in a plate press, and pressed for 1 minute at 288°C, using minimal force. The material that was taken out of the press was a one-sided composite material where the film was firmly attached to the reinforcing material.

A piece of this material was coated on the bare glass side with a contact adhesive (Armstrong "N-lll INDUSTRIAL ADHE-SIVE"). The same adhesive was applied to one side of a piece of polyester cotton fabric. After drying, the two glue-coated materials were pressed together to obtain a two-layer fabric having a surface of a perfluoroelastomer and a surface of polyester and cotton, which could well be used as a fabric.

Example 17L was a graphite-reinforced perfluoropolymer composite material prepared by using the material from Example 16D as a substrate and making a laminate as indicated in Example 17E. As mentioned earlier, the first layer on the substrate was derived from TE-5489, a low crystalline perfluoropolymer based dispersion. The resulting laminate was approx. 0.038 cm thick with a smooth elastic matrix that appears to have completely saturated the reinforced material.

Example 17M was a laminate made by attaching a 0.127 cm thick PTFE film (available from Chemplast Inc., Wayne, New Jersey) to both sides of a substrate from Example 17D, which again consisted of 15227 reinforcing material, silicone treated with a first layer of KALREZ followed by a top layer of a mixed fluoroelastomer-PTFE (FMK-4-10-B). The laminate was pressed under the following conditions: Plate temperature 382°C, pressure 10 tons of force on a piece measuring approx. 12.7

x 25.4 cm, press time approx. 5 minutes, cooled under pressure to 260°C and was then removed from the press. The finished fabric was 0.088 to 0.094 cm.- thick. Said PTFE appears to be strongly attached to the top layer. There was no tendency for separation, even after repeated tearing of small areas of the laminated overlay and attempts to tear the layers apart.

Examples 19 A - B.

Example 19A was prepared as follows: Chemfab Style 122 glass fabric was heat cleaned. A silicone oil lubricant/saturant and a first layer of PTFE were then applied simultaneously by a simple dip through a bath of FMK 4-10-A followed by drying and curing. The finished reinforcing material was laminated between 0.03 cm thick sheets of uncured calendered sheet identified as "Fluorel based Diak catalyzed fluoroelastomer compound suitable for flue duct applications" (Passaic Rubber Corporation, Clifton, N.J.) The rubber was brushed with acetone on the sides that was

in contact with the fabric before the materials were laid up, and then cured by pressing for 15 minutes at a plate temperature

at 176.6°C with a pressure from 17.8 to 21.1 kg/cm<2> (1 pc.)

and cooling under pressure to 93.3°C. The resulting reinforced rubber material was approx. 0.35 cm thick and was very pliable with good integrity.

Example 19B was prepared using the same method as in the preparation of the material from Example 19A, except that the substrate was 15227 as reinforcing material, and that the rubber was not brushed with acetone before application. The resulting material was 0.102 cm thick, and appeared as flexible as when compared to the material from Example 19A, and also had good integrity.

Examples 20 A - B.

A KALREZ crust that contained 1.5 parts per 100 parts of triallylisocyanate (TAIC) gum (manufactured by Nippon Kasei Chemical Company, Ltd., Tokyo, Japan, and available in the United States from Mitsubishi International Corporation, New York, New York) was prepared by adding the required amount of TAIC as a 5 % solution in denatured ethanol to the KALREZ dispersion and evaporate the treated latex to dryness at approx. 90°C. Addition of TAIC in this manner does not appear to induce a coagulation.

Two composite materials were prepared using the technique used to prepare Examples 17E, G, H

and J. One was prepared from materials from Example 17A and was designated Example 20A, while one was prepared using the material from Example 16A and was designated Example 20B.

Each of these materials was irradiated with a 1 MeV electron beam to an amount of 4, 8 and 16 megarads respectively. The amperage of the beam was 5 milliamps. Determination of dynamic moduli for the irradiated composites suggested that the radiation had induced a crosslink.

Example 21.

Composite material prepared as described in example 2 was laminated in a sheet press with a 0.012 cm thick FEP film as a hot melt adhesive between the layers, using the following lamination conditions:

plate temperature: 354°C

pressure: approx. 35.2 kg/cm<2>

printing time: 6 min.

Four examples of 2-layer laminates were produced and these differed in a relative orientation of the warp yarn in the layers. The examples were made with parallel warp yarns (0° deviation), 30° deviation, 45° deviation and 90° deviation.

Composite material prepared as indicated in example 2A was also laminated, using the same conditions as indicated above, but with lower pressure, i.e. approx. 19.7 kg/cm <2> (45 tons of force on a laminate that was about 45.7 x 45.7 cm). A warp yarn orientation of 0, 30, 45 and 90° was also used in these examples as well.

The laminates were tested for tensile strength and trapezoid tear strength. The results of the tests are given in Table XVI.

Example 22.

A knotted fiberglass fabric that weighed approx. 169.5 g/m 3 was given an uncoated dip through Dow Corning ET-4327, which was diluted 1:8 per volume of water, after which the material was dried and cured. The treated bonded substrate was then given a single dip in a KALREZ dispersion, dried and cured at 371.1°C. The treating reinforcing materials were placed between layers of a film manufactured by KALREZ, and the whole protected with aluminum foil treated with a silicone-free curing agent.l, was pressed between plates at 287.8°C

and a pressure of approx. 7.1 kg/cm 2 for 5 minutes, and then cooled under pressure. The resulting composite material was soft and pliable.

example 23.

In the same way as described in example 22, a material was produced, but with different lamination conditions (ie a plate temperature of o 382.2°C, a pressure of about 35 kg/cm 2 , and 3 minutes at this pressure temperature followed by cooling under pressure). The laminate was made with a film of FMK-4-10-B reinforced with a bonded fiberglass fabric that was primed with ET-4327 and dip coated in a KALREZ latex.

Examples 24 A-D.

A series of four materials was produced in the same way

as in Example 2A to compare PFA, FEP and PTFE as a top layer, and PFA and PTFE as the resin component of the perfluoropolymer/fluoroelastomer blend as a top layer. The composition of the composite materials is indicated in the following table.

All the composite materials were prepared in a similar manner as described in Example 2A. The first layer was applied by an uncoated hot dip. The overlying layers were applied by means of several layers, so-called semi-melting dips, so that the total fabric weight was 1356.3 g/m 2. The fabrics were then calendered to consolidate the semi-melted layers, then they were dry-melted, and finally the fabrics were finished with a single, uncoated melt dip through the top layer dispersions.

Samples of the materials were tested for physical properties, and the results are shown in the following table.

Examples 2 5 A-C

Pieces of copper foil, 0.08 mm thick, etched on one side (available from Yates Industries Inc. Bordentown, New Jersey, specific type "A" etch) were washed with soap and water, washed with distilled water, washed with acetone of ana -listening quality and then air-dried. The etched surface was treated with gamma-aminopropyltriethoxysilane (available from Union Carbide Corporation, New York, New York as A-1100) by dipping in a 1% aqueous solution and dried in an air circulating oven at 107.2°C. The laminate was then prepared and the treated foil substrate as shown in the following table:

TE-5489 supplied by DuPont contains a high temperature methyl-phenyl silicone oil. When the dispersion was dried to produce a crust and this crust is pressed into a film as described in Example 17E, the silicone oil will saturate and cover the films and prevent attachment of the other components to heat-pressed laminates. To remove this silicone, the cast film was cut open and washed in pure toluene in a Ross mixing emulsifier, dried in an air circulating oven at 50°C, and again pressed into a film. This was repeated 4 times and the resulting silicone-free film was used to prepare Example 25B.

The three examples are foils with durable compressible polymeric outer layers. Example 25B had a particularly soft but elastic coating which was very well attached to the copper surface. The coating can be scratched with a knife, but shows no tendency to delaminate, even in boiling water. Example 25C has a somewhat less elastic and softer surface than 25B, but appears equally resistant to delamination. Example 25A has coating properties equivalent to 25C, but was the most easily scratched with a knife of the three laminates.

Example 26.

A piece of plain 16 ga. cold-rolled steel was worn with a 200-grit sandpaper on one side, until the surface was clear and shiny, and free of air and light scale. The surface was washed with high quality acetone, air dried, immersed in a 6 N sodium hydroxide solution and left for several minutes, washed with distilled water and then air dried. The surface was treated with silane and a polymer film consisting of a resin made from TE-5489 (silicone free) and then pressed into a laminate as described in Example 25B. The result was a steel sheet with a soft and compressible and elastic coating that was firmly attached to the steel, and even when scratched with a knife, there was no tendency for delamination.

Example 27.

A piece of window glass with a thickness of 0.318 cm was washed with soapy water, washed with high-grade acetone, immersed in a 6 N sodium hydroxide solution for several minutes, washed with distilled water and air-dried. The surface was silane-treated, and a film of silicone-free TE-5489 was pressure-laminated on the glass substrate as described in examples 25B and 26, but a very low pressure was used, i.e. less than 3.5 kg/cm 2 on the test piece, and at the beginning the temperature of the surfaces was normal room temperature, but was slowly raised to 287.7°C during approx. 1/2 hour, of which+.' they were air-cooled to room temperature over several hours, so that heat shock was avoided which could have possibly broken the glass surfaces. Said TE-5489 produced an elastic 0.127 mm thick layer which did not delaminate even after boiling in water for 24 hours.

Example 28A.

A thin extruded coating of PTFE was applied by so-called paste extrusion onto an ECG 37 1/3 fiberglass yarn. The encapsulated yarn was then woven into a plain woven fabric

2

with approx. 14 x 15 traders per cm and with a weight of approx. 1186.7 g/m o (of which approx. 60% is PTFE). Top layer was imposed on follow-

end method: Cast films of FMK-4-10-B were laminated on both sides of the substrate in a plate press at a pressure of approx. 20 kg/cm. The plate temperature of 371°C was maintained for 5 minutes and then the material was cooled to approx. 65.6°C during 15 minutes under pressure. The resulting product weighed 1390.2 g/yr/ and had excellent physical integrity and was exceptionally flexible.

Example 28B.

A cast film of a 60/40 wt% blend of TE-3313 and

a fluoroelastomer (manufactured by L-9020) latex (manufactured by 3M) was laminated to the substrate of Example 28A. The resulting product had a flexibility and integrity comparable to the material of Example 28A.

Example 28C.

A woven substrate of the type described in Example 28A was given eight so-called semi-melting passes through FMK-4-10-B followed by a final dry-melting treatment. This resulted in a material that was 1.118 mm thick

and weighed 1778.7 g/m 2 . The product had excellent integrity and was somewhat more flexible than the material from Example 2A, although it was 20% heavier and approx. 30% thicker. The material was subjected to physical testing with the following results:

Example 29.

A substrate of Style 15227 glass cloth was heat cleaned and impregnated with an ET-4327 med-tylphenyl silicone emulsion.

A first layer of a perfluoroelastomer was applied in a single dip through a DuPont TE-5506 experimental low crystalline perfluorinated polymer in an aqueous dispersion with a specific density of 1.39 g/m"*.

A mixture containing 104 parts by weight was then prepared

TE-3313 (57.7% solid PTFE substances) and 154 parts by weight KALREZ latex (26% perfluoroelastomer substances). The mixture was evaporated to dryness in an air circulating oven at 90°C, and the resulting cake was cut up and washed several times in hot water in a Waring mixer, and again dried at 90° to coarse flake-like crusts. Using the technique described in Example 17E, said crust was pressed into a film and this laminated to the substrate. The substrate weighed 837.5 g/m .

The film and laminate were pressed under the following conditions: plate temperature 287.8°C, force on the plates, 20 tons

-> 2

(approx. 39.4 kg/cm<J> on the film and 77.3 kg/cm on the laminate), time at printing temperature, 3 min.

The resulting flexible product was approx. 0.102 cm thick

and had good physical integrity with an elastic, well-attached and tough outer layer.

Example 30.

A film was prepared from TE-5489 derived solids treated to remove silicone oil as described in Example 17E. 10 g of toluene-washed crust was pressed in a plate press between pieces of aluminum foil treated with a silicone release agent. The plate temperature was 162.8°C under a force of 1 ton for 1 min. The material was then cooled under pressure.

The resulting film was placed on a piece of 100% polyester bonded fabric, Style 5162, White, 1980 (manufactured by Armtex Inc., Pilot Mountain, North Carolina) and pressed as described in Example 17K, but with a plate temperature of 162 .8°C and a 10 ton force on the plates for 1 min.

A durable, flexible composite material with a thickness of approx. 0.038 cm. The bonded reinforcing material was completely encapsulated by perfluoroelastomer

the matrix.

Example 31.

Using the procedures described in Example 30, 5 g of TE-5489 fabrics were pressed into a film and laminated on one side to a piece of TYVEK spun poly-olefin, Style 1056D (manufactured by DuPont). The temperature of the press plates was 115.6°C, and these were used to laminate the material, and it was pressed for 2 minutes at a force of approx. 1 ton on the plates. After approx. 1 minute at the mentioned temperature and pressure, the material was cooled under pressure to approx. room temperature. The resulting laminate had a perfluoropolymer on one side (about 0.23 mm thick) and this layer was flexible and tough.

Examples 32 A and B.

By using the same procedure as described in the example

31, laminates of TE-5489 fluoroelastomer were made on two pieces of REEMAY spunbonded polyester (manufactured by DuPont). Example 32A included DuPont Style 2431 reinforcing material, while Example 32B contained DuPont Style 2024 reinforcing material. In both examples, the pressure conditions were as follows: plate temperature, 168.33°C, force on the plates, 2 tons, time at said temperature, 2 minutes, and cooling under pressure. The composite materials produced had a perfluoropolymer on one side and polymer on the other side. The composite materials were pliable and tough.

Example 33.

Example 33 was produced using materials and the technique indicated in example 30, but with a reduced laminating pressure, so that a composite material was produced with perfluoropolymer on one side of said Armtex Style No. 5162 polyester fabric. The pressure conditions were as follows: plate temperature, 168.33°C, force on the plates, 1-2 tons, time at said temperature, 1 minute, and cooling

under pressure.

The resulting laminated product was 0.30 mm thick and was more flexible and compliant than the material of Example 30. The polymer matrix was firmly bonded to the reinforcing material and there was no tendency to delaminate.

Example 34.

Using the technique described in Example 33,

a single-sided coated laminate was prepared using the resin derived from TE-5489 on a 50/50 polyester/cotton fabric, 152.4 cm wide (Style No. 443833 manufactured by Burlington Industries, New York, New York).

The resulting product was a durable, pliable and pliable laminate. The perfluoropolymer was firmly attached to one side. The unlaminated side of the composite material had retained its soft textile quality.

Examples 35A and B.

Examples 35A and B were prepared using the procedures described in Examples 2A and 2B, except that the DuPont VTR-5307 latex in the blend of PTFE and fluoroelastomer was replaced with an AFLAS TFE/propylene copolymer latex, which was prepared by Xenox Inc., Houston, Texas. The mixture was prepared by mixing 104 parts by weight of DuPont TE-3313 with 129 parts by weight of AFLAS latex, thereby obtaining

a 60/40 ratio between PTFE and fluoroelastomer. The composition of the materials from Examples 35A and B is shown below:

Physical properties of the materials from e.g. 35A and B are as follows:

Examples 36 A-C.

Example 36 A was prepared by the following procedure: ECB 150 4/3 fiberglass yarn was treated with silicone oil and impregnated with a TE-5506 low-crystalline perfluoropolymer (DuPont) by a single dip using a mixture of TE-5506 and an ET-4327 emulsion (Dow Corning), after which the yarn was dried and the perfluoropolymer melted. The bath was prepared by mixing 199 parts by weight of TE-5506

(50.3% solids) with 23 parts by weight of ET-4327 (35% solids), diluted with water to a specific gravity of

1.225 g/cm^. The ratio of perfluoropolymer to silicone polymer in the bath was 12.5 to 1 per weight.

The impregnated yarn as prepared above was woven into

a 14 x 14 fabric that weighed approx. 678.1 g/m 2. The woven fabric was then cured at approx. 287.8°C for 1 minute and used to prepare the material from Examples 36B and 36C in the following manner. Example 36B was prepared by applying to the material from Example 36A an intermediate layer of a PTFE-fluoroelastomer mixture weighing approx. 440.8 g/m 2 in four passes through FMK 4-10-B. The coating was melted by curing for 1 minute at approx. 31.1°C, and a top layer of TE-3313 (DuPont) PTFE diluted to a specific gravity of 1.30 was then applied. The final weight of the material was 1152.8 y/m 2.

The material of Example 36C was prepared by coating the material of Example 36A with an intermediate layer of PTFE by 6 dips in TE-3313 at a specific density of 1.485 followed by calendering, dry fusing and finally a final melt dip in TE-3313 at a specific density of 1.30.

No top team was imposed.

The materials from Examples 36B-C were physically tested with the following results:

Claims (10)

1. Composite material consisting of a substrate coated with a matrix, characterized in that the matrix consists of: A) a first layer of a perfluoropolymer selected from a perfluoroplastic, a perfluoroelastomer, a mixture of perfluoroplastic and perfluoroelastomer, or any combination thereof, possibly together with a lubricant; and B) an overlying layer of a fluoroelastomer, a fluoroplastic, a fluoroelastomer/fluoroplastic blend, or any combination thereof; and optionally C) an intermediate layer consisting of a fluoroelastomer located between the first layer and the overlying layer, and a topcoat selected from a fluoroplastic, a fluoroelastomer, a fluoroplastic/fluoroelastomer mixture or a combination thereof, where the substrate has optionally been treated with a coupling agent to promote bonding. 2. Composite material according to claim 1, characterized in that the overlying layer comprises a mixture of a fluoroelastomer and a fluoroplastic, where the fluoroelastomer makes up 10-90% by weight of the mixture. 3. Composite material according to claim 1, characterized in that the fluoroelastomer makes up 25-60% by weight of the mixture. 4. Composite material according to claim 1, characterized in that the resins in the layers are at least partially cross-linked. 5. Composite material according to claim 1, characterized in that only one side of the substrate is coated with a matrix. 6. Composite material according to claim 1, characterized in that the fluoroplastic comprises PTFE, PFA or FEP. 7. Composite material according to claim 1, characterized in that the fluoroelastomer is selected from copolymers of vinylidene chloride and at least one other fluorinated monomer selected from hexafluoropropylene; tetrafluoroethylene; chlorotrifluoroethylene; and pentafluoropropylene. 8. Composite material according to claim 1, characterized in that the perfluoroplastic comprises PTFE, PFA or FEP. 9. Composite material according to claim 1, characterized in that the perfluoroelastomer comprises a copolymer of TFE and perfluorovinyl ether such as PMVE or PPVE. 10. Composite material according to claim 1, characterized in that any fluoropolymer component can contain a functional group selected from carboxylic and sulfonic acids and their salts, halogen, and a reactive hydrogen on an alkyl side chain.