AU2016216529B2

AU2016216529B2 - Reinforced composite material

Info

Publication number: AU2016216529B2
Application number: AU2016216529A
Authority: AU
Inventors: Peter Clifford Hodgson
Original assignee: Mirotone Pty Ltd
Current assignee: Mirotone Pty Ltd
Priority date: 2005-10-17
Filing date: 2016-08-15
Publication date: 2018-06-21
Anticipated expiration: 2026-10-17
Also published as: AU2018229523A1; AU2016216529A1; AU2020244452A1

Abstract

Abstract The present invention relates to a reinforced composite material and a method for its production. The composite material comprises at least one cured resin having a reinforcing material. Preferably the reinforcing material is a plurality of glass fibres which are treated such that the properties of the interphase substantially surrounding each fibre are substantially equivalent to those of the bulk cured resin. The fibre treatment may be selected from the group consisting of a polymeric coating, a hydrophilic surface coating, a surface coating of a free radical inhibitor, or a reduction in the total surface area of the fibres. The reinforced composite material of the invention provides improved long-term mechanical properties compared to traditional glass fibre reinforced materials.

Description

The present invention relates to a reinforced composite material and a method for its production. The composite material comprises at least one cured resin having a reinforcing material. Preferably the reinforcing material is a plurality of glass fibres which are treated such that the properties of the interphase substantially surrounding each fibre are substantially equivalent to those of the bulk cured resin. The fibre treatment may be selected from the group consisting of a polymeric coating, a hydrophilic surface coating, a surface coating of a free radical inhibitor, or a reduction in the total surface area of the fibres. The reinforced composite material of the invention provides improved long-term mechanical properties compared to traditional glass fibre reinforced materials.

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2016216529 18 May 2018

Divisional status

Claims

is claimed from parent case Australian case AU2014201093, the entire contents of which is incorporated herein by reference.

- 1 REINFORCED COMPOSITE MATERIAL

FIELD OF THE DISCLOSURE

The present disclosure relates to reinforced composite materials, and in particular to fibre reinforced polymer composites. However, it will be appreciated that the disclosure is not limited to this particular field of use.

BACKGROUND OF THE DISCLOSURE

Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of the common general knowledge in the field.

Fibre reinforced polymer composites are known in the art and are commonly made by reacting a curable resin with a reactive diluent in the presence of a free radical initiator. Typically, the curable resin is an unsaturated polyester resin and the reactive diluent is a vinyl monomer. Reinforcing materials such as glass fibre are often included in the formulations to provide dimensional stability and toughness. Such reinforced composites are used in many key industrial applications, including: construction, automotive, aerospace, marine and for corrosion resistant products.

For traditional glass fibre reinforced polymer composites, the fibre lengths typically range from about 12 mm up to tens of metres in the case of, for example, filament winding.

In these glass fibre polymer composites the majority of fibres are held in position by mechanical friction and there is only relatively weak bonding of the fibres to the resin matrix. Therefore, the performance of such polymer composites is largely due to the length of the fibres employed and in these composites there is a discontinuity/gap between the fibres and the resin. Cracks initiated in the resin matrix find it very difficult to jump gaps, therefore in these composites cracks initiated in the

10256286_1 (GHMatters) P88209.AU.2

2016216529 18 May 2018 resin are usually arrested at the resin boundary and do not reach the glass surface. However, traditional glass fibre composites have a number of shortcomings. For example, it is difficult to wet the fibres with the resin prior to curing, and even dispersion of long fibres throughout the composite is difficult, especially for complex parts.

In addition, such traditional glass reinforced polymer composites are limited by their production techniques which generally require manual layering or are extremely limited in the shape and complexity of the moulds.

To overcome these shortcomings, very short glass fibres may be used. VSFPLCs or very short fibre polymerisable liquid composites can product laminate with tensile strengths greater than 80 MPa flexural strength greater than 130 MPa. VSFPLCs are suspension of very short surface treated reinforcing fibres and polymerisable resins/thermoset such as UP resins vinyl functional resins, epoxy resins or polyurethane resins. The length of the fibres are kept very short so that they do not increase the viscosity of the liquid to where the resin fibre mixture is no longer sprayable or pumpable. VSFPLCs can be used to replace standard fibre glass layouts in open and closed moulding applications and also can be used as alternatives to thermoplastics in resin injection moulding and rotation moulding applications.

However, an improvement in the fibre-to-matrix bond is typically required since such very short glass fibres are too sholt to be mechanically keyed into the matrix. Coating the reinforcing fibre with a coupling agent may provide an improvement in the fibre-to-matrix bond. For example, one commonly used coupling agent is Dow Coming Z-6030, which is a bifunctional silane containing a methacrylate reactive organic group and 3 methoxysilyl groups. Dow Coming Z-6030 reacts with organic thermoset resins as well as inorganic minerals such as the glass fibre. Whilst such coupling agents may

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2016216529 18 May 2018 improve the fibre-to-matrix bond, the usefulness of the reinforced polymer composite is limited since they are prone to embrittlement over time. A product with greater flexibility and toughness is sometimes needed.

An attempt was made to address some of these shortcomings in PCT Patent

Application No. PCT/AUO1/01484 (International Publication No. WO 02/40577) where the coupling agent was pre-polymerised prior to coating the glass reinforcing fibre to plasticise the interface. The intention of the pre-polymerised coupling agent was to provide a rubbery interphase between the fibre and the bulk resin and thereby result in product having improved impact resistance and strength. However, long-term embrittlement is still an issue with the above PCT. In Very Short Fibre Polymerisable Liquid Composites there are no air gaps between the fibre and the resin. In VSFPLCs the resin is chemically bonded to the resin matrix and there are no gaps between the resin and the fibres. Cracks initiated in the resin matrix travel directly to the fibre surface. All the energy of the propagating crack is focused at a point on the glass fibre, and the energy is sufficient to rupture the fibre. Abundant evidence for this can be seen on the fracture surface of silane treated fibres. This is especially true for laminates with flexural strengths greater than 100 MPa.

It may be desirable for an embodiment of the disclosure to overcome or ameliorate at least one of the disadvantages of the abovementioned prior art, or to provide a useful alternative.

SUMMARY OF THE DISCLOSURE

The disclosure provides a moulded composite material, comprising a cured reinforced composite material, wherein the cured reinforced composite material comprises at least one cured resin having:

i) a polymer to produce a polymer-modified resin; and ii) a plurality of reinforcing fibres coated with a coupling agent, the cured resin

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2016216529 18 May 2018 adjacent to said reinforcing fibres defining an interphase, wherein the coated plurality of reinforcing fibres are treated such that the properties of said interphase are substantially equivalent to those of the bulk cured resin.

The at least one cured resin may have between 5 to 50 % w/w of the polymer to produce a polymer-modified resin. The cured resin may have flexural toughness greater than about 3 Joules when tested in a standard flexure test, the test piece having dimensions about 100 mm in length, 15 mm in width and 5 mm in thickness. The treatment may be a polymeric coating and/or a hydrophilic surface coating applied to said coated plurality of reinforcing fibres. In some embodiments:

i) the polymer of said polymeric coating may be a monomer deficient low activity unsaturated polyester resin; or ii) the hydrophilic surface coating may be prepared by reacting a vinyl functional silane with a polyol.

The coupling agent may be a vinyl functional silane. The reinforcing fibre of the plurality of reinforcing fibres may be a glass fibre. The curable resin may be chosen or modified with said polymer to have predetermined properties. The properties may be chosen from one or more of tear resistance, strength, toughness and resistance to embrittlement. The unsaturated polyester resin may be provided by reacting a polyol with an acid;

wherein:

i) the polyol may comprise propylene glycol, methyl propanediol, neopentyl glycol, or diethyleneglycol;

ii) the acid may comprise terephthalic acid, isophthalic acid, fumaric acid, or 1,4-cyclohexane diacid; and iii) the unsaturated polyester resin may comprise a saturated to unsaturated acid ratio of between about 1.2:1 to 2:1.

In some embodiments, the treatment may:

i) reduce catalysation of resin polymerisation in the interphase when compared to a fibre not treated; or

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2016216529 18 May 2018 ii) reduce embrittlement of said interphase when compared to a fibre not treated.

The disclosure also provides a moulded composite material, comprising a cured reinforced composite material, wherein the cured reinforced composite material comprises:

i) a plurality of hydrophilic surface-modified reinforcing glass fibres, wherein the hydrophilic surface-modified reinforcing glass fibre comprises a reinforcing glass fibre modified with a hydrophilic surface coating comprising:

a) a first coating of a vinyl functional silane coupling agent; and

b) a second coating of the product of a vinyl functional silane coupling agent reacted with a polyol;

ii) at least one cured polyester resin; and iii) at least one interphase defined by the at least one cured polyester resin adjacent to the at least one hydrophilic surface-modified reinforcing glass fibre of the plurality of hydrophilic surface-modified reinforcing glass fibres;

wherein the at least one interphase has one or more properties substantially equivalent to those of the bulk at least one cured polyester resin, selected from the group consisting of: strength, flexural toughness, brittleness, density, cross-link density, chemical resistance, molecular weight, or degree of crystallinity, or a combination thereof.

The at least one cured polyester resin may be an at least one cured unsaturated polyester resin. The at least one cured polyester resin may be an at least one cured hydrophilic, unsaturated polyester resin. The polyester of said at least one cured polyester resin may have less than 33% w/w of monomer content. The polyester resin may be provided by reacting a polyol with an acid, wherein:

i) the polyol may comprise propylene glycol, methyl propanediol, neopentyl glycol, or diethyleneglycol;

ii) the acid may comprise terephthalic acid, isophthalic acid, fumaric acid, or 1,4-cyclohexane diacid; and iii) the unsaturated polyester resin may comprise a saturated to unsaturated acid

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2016216529 18 May 2018 ratio of between 1.2:1 to 2:1.

In some embodiments the at least one cured polyester resin may have flexural toughness greater than 3 Joules when tested in a standard flexure test, the test piece having dimensions 100 mm in length, 15 mm in width and 5 mm in thickness. The monomer content of said polyester may be between 5 to 30 % w/w. The vinyl functional silane coupling agent may be selected from the group consisting of Dow Coming Z-6030 (methacryloxypropyltrimethoxysilane), Z-6032 (vinylbenzylaminoethylaminopropyl-trimethoxysilane), and Z6075 (vinyl-tris(acetoxy) silane). The cured reinforced composite material may have flexural toughness greater than 3 Joules for up to 5 years. In some embodiments, the hydrophilic surface-modification of the reinforcing glass fibres may:

a) reduce catalysation of resin polymerisation in the interphase when compared to a fibre not treated; or

b) reduce embrittlement of said interphase when compared to a fibre not treated.

The disclosure also provides a moulded composite material, comprising:

i) a plurality of reinforcing fibers treated with a hydrophilic surface coating comprising the product of a vinyl functional silane coupling agent reacted with a polyol;

ii) at least one cured resin; and iii) at least one interphase defined by the at least one cured resin adjacent to and substantially surrounding at least one reinforced fiber of the plurality of reinforcing fibers;

wherein the hydrophilic surface coating of said plurality of reinforcing fibers results in the at least one interphase having one or more properties substantially equivalent to those of the bulk cured resin.

In some embodiments:

a) the coupling agent may comprise methacryloxypropyl-trimethoxysilane, vinylbenzylaminoethylaminopropyl-trimethoxysilane, or vinyl-tris(acetoxy) silane; and

b) the polyol may comprise a tri-hydroxy compound or a tetra-hydroxy compound. The tri-hydroxy compound may be trimethylolpropane and/or the tetra-hydroxy

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2016216529 18 May 2018 compound may be pentaerythritol. The one or more properties of said at least one interphase may comprise:

i) a mechanical property, comprising strength, toughness, or brittleness; or ii) a physical or chemical property, comprising density, cross-link density, chemical resistance, molecular weight, or degree of crystallinity.

The at least one cured resin may be a polymer-modified resin. The polymer-modified resin may comprise between 5 to 50 % w/w of the polymer. The polymer-modified resin may have one or more of the following properties: tear resistance, strength, toughness, or resistance to embrittlement. The polymer-modified resin may have flexural toughness greater than 3 Joules according to a standard flexure test using a test piece of 100 mm length, 15 mm width, and 5 mm thickness. The hydrophilic surface coating of the plurality of reinforcing fibers may:

a) reduce catalyzation of resin polymerization in the at least one interphase when compared to an untreated fiber; or

b) reduce embrittlement of said at least one interphase when compared to an untreated fiber.

The reinforcing fiber of the plurality of reinforcing fibers may have a length of between 100 and 1000 microns. The flexural toughness may be greater than 3 Joules for up to 5 years. The reinforced composite material may comprise one or more of the following: i) a flexural modulus of greater than about 3.1 GPa; ii) a flexural stress of greater than about

120 MPa; or iii) an elongation at break of greater than about 2%. The flexural modulus may be greater than about 3.5 GPa.

An embodiment provides a method for producing a reinforced composite material, comprising: combining at least one curable resin and a plurality of reinforcing fibres; and curing the at least one curable resin, the cured resin adjacent the reinforcing fibres defining an interphase, wherein the reinforcing fibres are treated such that the properties of the interphase are substantially equivalent to those of the bulk cured resin.

In a preferred embodiment the reinforcing fibres may be glass fibres having a

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2016216529 18 May 2018 coupling agent coupled thereto. The glass fibres may be chosen from E-, S- or C-class glass. The glass fibre length may be typically between about 100 and 1000 microns and the fibres may preferably be evenly dispersed through the resin. The coupling agent may comprise a plurality of molecules, each having a first end adapted to bond to the glass fibre and a second end adapted to bond to the resin when cured. Preferably the coupling agent may be Dow Coming Z-6030. However, other coupling agents may be used such as Dow Coming Z-6032, and Z-6075. Similar coupling agents may be available from De

Gussa and Crompton Specialties.

The properties of the interphase which are substantially equivalent to those of the bulk resin may be mechanical properties selected from the group consisting of strength, toughness, and brittleness. Alternatively, or additionally, the properties may be physical or chemical properties selected from the group consisting of density, cross-link density, molecular weight, chemical resistance and degree of crystallinity.

The curable resin(s) may preferably include a polymer and may be chosen to have predetermined properties including from one or more of improved tear resistance, strength, toughness, and resistance to embrittlement. Preferably the resin may be chosen such that in its cured state it may have a flexural toughness greater than 3 Joules according to a standard flexure test for a test piece having dinlensions about 100 mm length, 15 mm width and 5mm depth. Ideally the cured resin having the polymer may have a flexural toughness greater than 3 Joules up to 5 years following production.

In preferred embodiments the cured resin may be resistant to crack propagation. A preferred cured resin may be able to supply fibrils in enough quantity and with enough inherent tensile strength to stabilise the craze zone ahead of the crack, limiting or preventing the propagation of a crack. Ideally the polymer-modified curable resin may arrest the crack before it can reach the surface of the glass fibre, or if the craze ahead of the crack reaches the glass it may have insufficient energy to rupture the glass fibre surface. Such toughened resins may ideally be suited to very short fibre reinforced composites. In addition, such resins may provide reduced embrittlement with age.

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NOTE: The very surface of the glass fibre is nowhere near the strength of the fibre itself due to vastly different cooling rates between the surface of the glass fibre and the body of the glass fibre. This surface is very easily ruptured. To illustrate this one has only to look at the process for making glue-chipped decorative glass panels.

The treatment applied to the fibres may preferably be a treatment that reduces catalysation of resin polymerisation in the interphase. In one embodiment the treatment applied to the reinforcing fibres may be the application of a polymeric coating. Preferably the polymer of the polymeric coating may be a monomer deficient (less than about 33% w/w monomer) low activity unsaturated polyester resin having only a relatively moderate amount of unsaturation. Desirably the unsaturated polyester resin may be formulated to be substantially hydrophilic.

In another embodiment, the treatment applied to the reinforcing fibres may be the application of a hydrophilic surface coating. Reacting the coupling agent (coating the glass fibre) with a hydrophilic agent may provide the hydrophilic surface coating. In a preferred aspect the hydrophilic agent may be provided by reacting Dow Coming Z-6030 with a tri-hydroxy compound, such as trimetholylpropane, or a tetra-hydroxy compound, such as pentaerythritol in the presence of a catalyst, such as tri-butyl tin. The glass reinforcing fibre may be sufficiently coated with the hydrophilic surface coating such that the modified fibre is substantially hydrophilic.

In a further aspect of the hydrophilic surface coating embodiment, the treated glass fibre may be further treated with an emulsion. The treatment may simply be mixing, however compounding is preferred. The emulsion may preferably comprise:

16.6 parts water;

100 parts acetone;

and

200 parts polymer,

Optionally the emulsion may comprise free radical inhibitors, which generally include

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2016216529 18 May 2018 hydroquinone (HQ) or hindered amines. The polymer may be a vinyl ester resin, however the polymers referred to above may be preferred. In particular, the polymer may be a monomer deficient (less than about 33% w/w monomer) low activity unsaturated polyester resin having only a relatively moderate amount of unsaturation. Desirably the unsaturated polyester resin may be formulated to be substantially hydrophilic.

In a further embodiment the treatment applied to the reinforcing fibres may be the application of a coating of a free radical inhibitor, such as hydroquinone acetyl acetone, hindered phenols or hindered amines. In yet a further embodiment the treatment applied to the reinforcing fibres may be the reduction in the total surface area of the reinforcing fibres.

As discussed above, very short fibre polymerisable liquid composites typically require the use of coupling agents to improve the fibre-to-matrix bond since the fibres are too short to mechanically key into the matrix. The present applicants have found that use of such coupling agents tends to cause embrittlement of the reinforced composite material over time. Others have attempted to mitigate such embrittlement by using a blend of resins whereby at least one of the resins is rubbery. Other alternatives have been to modify the coupling agent to provide a rubbery phase surrounding the fibre, such as disclosed in WO 02/40577. The present disclosure takes an entirely different approach.

Without wishing to be bound by theory, it is believed that prior art coupling agents coated to the glass fibre act to catalyse resin polymerisation in the interphase, ie the region directly adjacent the glass fibre, thereby forming a brittle interphase over time.

The approach of some embodiments of the present disclosure is to chemically passivate the coupling agent coating, thereby attempting to mitigate any effects which the coupling agent may have on the fibre-resin interphase, and enabling the interphase to have substantially equivalent properties to those of the bulk cured resin. However, as the skilled person will appreciate, the degree of passivation should be sufficient to mitigate any effects which the coupling agent may have on the fibre-resin interphase whilst still achieving sufficient bonding of the fibre to the bulk resin.

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The applicants have found that some embodiments of the present disclosure, which is entirely contradictory to the prior art, may somewhat surprisingly provides a reinforced composite material which exhibits relatively reduced embrittlement as compared to prior art glass reinforced composite materials whilst retaining properties such as strength, toughness and heat distortion temperature. In particular, the long-term embrittlement issue of prior art composites employing coupled fibres may notably be reduced.

The disclosure also provides a reinforced composite material comprising: at least one cured resin having a plurality of reinforcing fibres, the cured resin adjacent the reinforcing fibres defining an interphase, the interphase having properties substantially equivalent to those of the bulk cured resin.

The disclosure also provides a method for treating a reinforcing fibre for use in a composite material including a curable resin, the method comprising the step of applying one or more of a polymeric coating, a hydrophilic surface coating, or a coating of a free radical inhibitor to the reinforcing fibre such that, in use, the cured resin adjacent the reinforcing fibre defines an interphase, the interphase having properties substantially equivalent to those of the bulk cured resin.

The disclosure also provides a reinforcing fibre for use in a composite material including a curable resin, the reinforcing fibre having one or more of a polymeric coating, a hydrophilic surface coating, or a coating of a free radical inhibitor applied thereto such that, in use, the cured resin adjacent the reinforcing fibre defines an interphase, the interphase having properties substantially equivalent to those of the bulk cured resin.

The disclosure also provides a method for reducing embrittlement in a composite material having a curable resin and a plurality of reinforcing fibres dispersed therethrough, the cured resin adjacent the reinforcing fibres defining an interphase, the method comprising the step of reducing the total surface area of the reinforcing fibres thereby providing a corresponding decrease in the quantity of the interphase.

The disclosure also provides a moulded composite body as set forth above.

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2016216529 18 May 2018

The disclosure also provides a treated reinforcing fibre as set forth above.

The disclosure also provides a method for moulding a composite comprising the steps of providing a mixture of at least one curable resin and a plurality of reinforcing fibres as set forth above, applying the mixture to a mould and curing the at least one curable resin.

The disclosure also provides a moulded composite material when produced by the method as set forth above.

The disclosure also provides a liquid curable composite comprising at least one curable resin and a plurality of reinforcing fibres such that, in use, the cured resin adjacent said reinforcing fibres defines an interphase, wherein said reinforcing fibres are treated such that the properties of said interphase are substantially equivalent to those of the bulk cured resin.

The disclosure also provides a liquid curable composite comprising at least one curable resin and a plurality of reinforcing fibres, said reinforcing fibres having one or more of a polymeric coating, a hydrophilic surface coating, or a coating of a free radical inhibitor applied thereto such that, when cured, the cured resin adjacent said reinforcing fibre defines an interphase, said interphase having properties substantially equivalent to those of the bulk cured resin.

Unless the context clearly requires otherwise, throughout the description and the claims, the words 'comprise', 'comprising', and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of including, but not limited to.

Other than in the examples, or where otherwise indicated, all numbers expressing quantities of ingredients or reaction conditions used herein are to be understood as modified in all instances by the term about. The examples are not intended to limit the scope of the disclosure. In what follows, or where otherwise indicated,% will mean weight %, ratio will mean weight ratio and parts will mean weight parts.

In describing and claiming the present disclosure, the following terminology will be

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2016216529 18 May 2018 used in accordance with the definitions set out below. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

Throughout this specification the terms fibre and fibres are to be taken to include platelet and platelets respectively. Glass fibres may be the most suitable fibres for the disclosure. However other mineral fibres such as wollastonite and ceramic fibres may also be used without departing from the scope of the disclosure.

Throughout this specification the terms property and properties are to be taken to include typical mechanical, physical and chemical properties of polymers and cured resins. For example, mechanical properties are those selected from the group consisting of flexural and/or tensile strength, toughness, elasticity, plasticity, ductility, brittleness and impact resistance. Chemical and physical properties are those selected from the group consisting of density, hardness, cross-link density, molecular weight, chemical resistance and degree of crystallinity.

Throughout this specification the terms catalyse and catalysation are to be taken to be synonymous with the terms initiate and initiation in relation to free radical polymerization.

It will also be understood that the term material in the present application refers to liquid and solid forms of the fibre/resin mixture. The material itself can be provided in cured form, uncured liquid form or as a separate component e.g. reinforcing fibres and resin separately for mixing on site.

BEST MODE FOR CARRYING OUT EMBODIMENTS OF THE DISCLOSURE

The present disclosure provides a method for producing a reinforced composite material and the composite body produced by the method. The method comprises the steps of combining at least one curable resin with a plurality of reinforcing fibres such that the fibres are substantially evenly dispersed throughout the resin, and curing the resin. Preferably the resin is a vinyl ester resin having about

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2016216529 18 May 2018

40% of a reactive diluent, such as styrene monomer, ffowever, other monomers may also be used, such as mono- and di- and tri-functional acrylates and methacrylates. Alternatively, the resin may be chosen from unsaturated polyester resins, epoxy vinyl ester resins, vinyl function resins, tough vinyl functional urethane resins, tough vinyl functional acrylic resins, and non-plasticised flexible polyester resins, and combinations thereof.

In preferred embodiments, the fibres are glass fibres chosen from E-, S- and Cclass glass having a length of between about 100 and 1000 microns, ffowever, fibres having lengths greater than 1000 microns can also be used. Preferably any sizing agent is removed from the glass fibre prior to its treatment with the coupling agent(s). The preferred coupling agent is Dow Coming Z-6030. ffowever, other coupling agents may be used such as Dow Coming Z-6032 and Z-6075.

The, at least one curable resin may include a polymer, is chosen or modified with such a polymer to have predetermined properties chosen from one or more of improved tear resistance, strength, toughness, and resistance to embrittlement. Preferably the polymermodified cured resin has a flexural toughness greater than 3 Joules for up to 5 years following production for a test piece having dimensions about 110 mm length, 15 mm width and 5 mm depth subjected to a standard flexure test.

In preferred embodiments the polymer-modified curable resin is resistant to crack propagation. Such polymer-modified resins provide reduced embrittlement with age. Preferably the polymer is a monomer deficient (less than about 30% w/w monomer) low activity unsaturated polyester resin having only a relatively moderate amount of unsaturation. Examples of such polyesters are provided in the tables below. Desirably these polyesters are hydrophilic.

Once the resin is cured to provide the reinforced composite material, the cured resin adjacent and substantially surrounding each of the glass reinforcing fibres defines an interphase, and the reinforcing fibres are treated prior to their addition to the curable resin such that the properties of the interphase are substantially equivalent to those of the bulk

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2016216529 18 May 2018 cured resin. In one embodiment, the treatment applied to the fibres is a polymeric coating. The polymer of the polymeric coating is preferably the low activity unsaturated polyester resin described above.

As discussed above, without wishing to be bound by theory the applicant believes that a fibre treated with prior art coupling agents acts to catalyse resin polymerisation thereby forming an interphase having substantially different properties to the bulk cured resin. An interphase having highly cross-linked material will have properties vastly different to those of the bulk resin, thereby affecting the mechanical and physical properties of the final cured reinforced composite body. For example, an interphase having highly cross-linked material is inherently more brittle than the bulk resin. During fracture, a propagating crack will relatively easily rupture this brittle interphase and any crack-arresting properties of the resin in the interphase will substantially reduce. Further, as the skilled person will appreciate, the more fibre employed in the composite body the greater the total amount of brittle interphase will result, and the more brittle the composite body will become.

By treating the coupled glass fibre to reduce catalysation of free radical polymerisation, the applicants have been able to reduce the effect of the coupled glass fibre on the interphase such that the interphase has similar properties to the bulk cured resin. In other embodiments, the surface of the glass fibre is treated with a coating of one or more free radical inhibitors, such as hydroquinone or acetyl acetone, hindered phenols and hindered amines. The coating of free radical inhibitor(s) is associated with the surface of the glass fibre such that catalysation of resin polymerisation in the interphase is reduced and the interphase has similar properties to the bulk cured resin.

In a further embodiment, the treatment is a reduction in the total surface area of the fibres. For example, this may be achieved by substituting the glass fibre with a glass fibre having a relatively larger diameter. To explain, glass fibres typically used in glass fibre reinforced composites have diameters between about 5-12 microns. However, the applicants have discovered that use of glass fibres having diameters between about 15-24

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2016216529 18 May 2018 microns provides significantly less embrittlement to the final properties of the reinforced composite body, since for a given weight of glass fibre the total surface area is inversely proportional to the increase in fibre diameter. Of course even larger diameter fibres can be used than 24 micron, however, there is a practical working limit of the fibre properties.

In this embodiment, whilst the glass surface still may catalyse resin polymerisation to produce a brittle interphase, the total amount of brittle interphase material is relatively reduced. In addition, to provide a final cured polymer composite with similar mechanical properties, the length of relatively larger diameter glass fibre used is preferably longer than that which would ordinarily be employed for the relatively smaller diameter fibre.

As the skilled person would be aware, combinations of the above-described embodiments may also be employed where appropriate. For example, it would be possible to use glass fibres having a relatively larger diameter and coat the fibre with a free radical inhibitor, or coat the fibre with a polymer as described above.

In further embodiments, the treatment comprises a two-step process whereby the glass fibre is firstly coated with a first agent and then a second agent is reacted with the first agent to provide a substantially hydrophilic surface-modified glass fibre. Preferably the first agent is a coupling agent having a first end adapted to bond to the fibre, and a second end adapted to bond either to the second agent or the resin when cured. In a preferred embodiment, the coupling agent is methacryloxypropyltrimethoxysilane (Dow

Coming Z-6030). The second agent comprises the reaction product between the first agent and a tri-hydroxy compound such as trimetholylpropane. However, in alternative embodiments the hydroxy compound is a tetra-hydroxy compound such as pentaerythritol. The reaction of Z-6030 and trimetholylpropane is conducted in the presence of a tin catalyst, such as tri-butyl tin, under appropriate reaction conditions.

The method of treating the glass fibre according to the previous embodiment further includes the step of mixing or compounding the coated reinforcing fibre with an emulsion. The emulsion preferably comprises: 16.6 parts water, 100 parts acetone and

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200 parts polymer, wherein the polymer is preferably the hydrophilic low activity unsaturated polyester resin discussed above. The emulsion may also include a hydrophilic free radical inhibitor such as HQ.

EXAMPLES

The present disclosure will now be described with reference to the following examples which should be considered in all respects as illustrative and non-restrictive.

Treatment of a glass fibre with a hydrophilic surface coating

1. E-glass fibres were cut to an average fibre length of 3400 micron and then milled to an average length of 700 micron.
2. The milled glass fibres were cleaned using boiling water, with a strong detergent and with powerful agitation. The detergent was then rinsed from the fibres.
3. 1% w/w of methacryloyloxypropyltrimethoxysilane (Dow Z-6030) was suspended in water at pH 4 and the fibres added to the suspension. The resulting mixture was stirred vigorously at room temperature for 60 minutes.

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2016216529 18 May 2018
4. The liquid was then drained from the glass fibres, leaving them still wet with the mixture.
5. The Z-6030-treated fibres were then redispersed in water at a pH of 7.
6. Separately, a solution of Z-6030 was reacted with trimetholylpropane (TMP) in the presence of a tin catalyst (eg tributyl tin) for 15-20 minutes at 110-120 °C to form a Z-6030-TMP adduct having a viscosity of about 1200-1500 cP. Methanol is evolved during the reaction.
7. The Z-6030 treated fibres were then reacted with the Z-6030-TMP adduct to provide a hydrophilic treated fibre. This was achieved by dispersing the Z-6030 treated fibres in water and adding the Z-6030-TMP adduct to the water at a concentration of about 2-3 wt% of fibres. The mixture was stirred together for approximately 10 minutes. The fibres were then separated and then centrifuged to remove excess water. The wet fibres were then dried, initially at 30 °C for

3-4 hours, and then heated to between 110 and 125 °C for 5-7 minutes.
8. Separately, an emulsion of polymer was prepared having 200 parts polymers,

100 parts acetone and 16.6 parts water. Preferably the polymer is a hydrophilic resin such as an unsaturated polyester.
9. The hydrophilic treated fibres were then compounded with the emulsified resin until evenly distributed in the rations of about 93 w/w% fibres and 7 w/w% emulsion.

10. The compounded fibre-emulsion mixture was then added to the base resin at approximately 10-45% fibre-emulsion to 90-55% resin.

Table 1 provides flexural strength data for cured clear casts of the commercially available Derakane epoxy vinyl ester resin 411-350 (Ashland Chemicals). These test panels were prepared according to the manufacturers specifications and the resulted in

1 ifiHMaHpn!) Ρ88?Γ)0ΔΙΙ ?

2016216529 18 May 2018 flexural modulus averages about 3.1 GPa, the flexural stress at yield averages about 120 MPa, and the elongation at break averages between about 5 to 6%.

Table 2 shows similar test panels to those of Table 1 but having been thermally aged.

Panels are thermally aged by heat treatment at 108 °C for two hours follows by controlled cooling to below 40 °C over about 2 hours. As can be seen, within experimental error, the flexural modulus and flexural stress are about the same post aging. However, the elongation at break has approximately halved, meaning that the panels have substantially embrittled with accelerated aging.

Composite Flexural Modulus (GPa) Flexural Stress at Yield (MPa) Elongation at Break (%) Test Panel 1 2.98 112 4.9 Test Panel 2 3.12 119 5.7 Test Panel 3 3.11 123 5.6 Test Panel 4 3.28 132 6.0 Table 1: Flexural strength data for cured (un-aged) clear casts of Dera cane 411-350 Epoxy

Vinyl Ester Resin.

Composite Flexural Modulus (GPa) Flexural Stress at Yield (MPa) Elongation at Break (%) Test Panel 5 3.30 117 3.0 Test Panel 6- 3.40 121 3.1 Test Panel 7 3.10 131 4.1 Test Panel 8 3.20 123 3.6 Test Panel 9 3.20 127 4.2

Table 2: Flexural strength data foraged clear casts of Derakane 411-350 Epoxy Vinyl EsterResin.

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Table 3 provides flexural strength data for aged cured clear casts of Derakane epoxy vinyl ester resin with various polymer additions (discussed below). As can be seen, the resulting flexural modulus averages about 3.3 GPa, the flexural stress at yield averages about 135 MPa, and the elongation at break averages between about 5 to 7%. Comparing the elongation data between Tables 2 and 3 it can be seen that the various polymer additions have substantially reduced aged embrittlement.

Composite Flexural Modulus (GPa) Flexural Stress at Yield (MPa) Elongation at Break (%) Test Panel 10 +polymer 1 3.20 132 6.7 Test Panel 11 + polymer 2 3.20 131 4.9 Test Panel 12 +polymer 3 3.30 136 5.7 Test Panel 13 +polymer 4 3.50 140 6.0 Test Panel 14+polymer 5 3.60 146 6.6

Table 3: Flexural strength data for aged clear casts of Derakane 411-350 Epoxy V inyl Ester Resin having 12-15 wt% ofapolymer additive.

The polymers provided in the tables are the condensation products of a polyol and a diacid. The polyol's and diacid's comprising each polymer are provided in Table 4. These polyesters are generally prepared by heating approximately equimolar amounts of diol and acid at temperatures in excess of about 200 °C for periods of about 4 to about 12 hours. Most of the unsaturation is present as fumarate diester groups. These polyesters have acid numbers in the range of from about 15 to about 25. (The acid number is the milligrams of potassium hydroxide needed to neutralize one gram of sample).

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A 3-liter, round-bottomed flask equipped with a paddle stirrer, thermometer, an inert gas inlet and outlet and an electric heating mantle. The esterification reactions were conducted in 2 stages. The first stage was reacting the saturated acids in excess glycol, and the second stage was carried out with the addition of the unsaturated acids and remaining glycols. The reactor vessel was weighed between the stages and glycols were added if needed to compensate for any losses. The mixture was heated to between 150 and 170 °C such that water was liberated and the condenser inlet temperature was greater than 95 °C.

During the next 2-3 hours the temperature of the mixture was raised to 240 °C. The mixture was then cooled to 105 °C and blended with inhibited styrene. The final polyester resin contained 80 percent by weight of the unsaturated polyester and 20 percent styrene.

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Polymer polyol diacid ratio of saturated to unsaturated acids Polymer 1 propylene glycol 4 terephthalic acid 2 3:2 moles, MP-diol 1.5 moles, isophthalic moles acid 1 mole, fumaric acid 2 moles Polymer 2 diethylene glycol 5.5 terephthalic acid 3 3:2. Also, a 0.5M excess moles moles, fumaric acid 2 glycol was maintained at moles the commencement of the second stage Polymer 3 diethylene glycol 6 1,4-cyclohexane 4:3 moles, MP-diol 1.5 diacid, fumaric acid moles Polymers 4 Nuplex 316 / Tere and 7 phth 50/50 blend Polymer 5 neopentyl glycol 6.25 1,4-cyclohexane 3:2 moles, propylene diacid 4.5 moles, glycol 2 moles fumaric acid 3 moles Polymer 6 diethylene glycol 1,4-cyclohexane 3:2 diacid 3 moles, fumaric acid 2 moles Polymer 8 neopentyl glycol 6.25 1,4-cyclohexane 4:3 moles, propylene diacid 4 moles, glycol 1 mole fumaric acid 3 moles

Table 4: Polyesters used to modify the Derakane base resin in Tables 3 and 5.

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Table 5 provides flexural strength data for Derakane epoxy vinyl ester resin having the stated ratios of resin to glass fibre (in brackets) wherein the glass fibre is treated only with the Z-6030 coupling agent.

Composite Flexural Modulus (GPa) Flexural Stress at Yield (MPa) Elongation at Break (%) Test Panel 15 (2.3:1) 6.20 124 0.87 Test Panel 16(2:1) 6.70 129 0.70 Test Panel 17(1.9:1) 7.50 135 0.63 TestPanel 18(1.7:1) 8.10 142 0.60 Test Panel 19(1.6:1) 9.00 149 0.58

Table 5: Flexural strength data for aged Z-6030 treated glass fibres in Derakane 411-350 epoxy vinyl ester resin.

Table 6 shows flexural strength data for aged test panels of Derakane epoxy vinyl ester resin having about 12-15 weight % of a polymer additive as described above and 45-50 weight % of a treated glass fibre according to the present disclosure.

Composite Flexural Modulus (GPa) Flexural Stress at Yield (MPa) Elongation at Break (%) Test Panel 20 + polymer 5 6.10 136 2.6 Test Panel 21 + polymer 6 6.20 133 2.2 Test Panel 22 + polymer 6 5.90 129 2.9 Test Panel 23 + polymer 7 6.00 134 3.1 Test Panel 24 + polymer 8 6.20 135 3.4 Table 6: Flexural strength data for aged Derakane 4 1-350 epoxy vinyl ester resin having 12

15 wt% of a polymer additive and 47 wt% of treated glass fibre m9RR9ftR 1

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2016216529 18 May 2018 according to the present disclosure, wherein the treatment comprises the hydrophilic surface coating and the emulsified polymer.

In the comparison of the flexural data provided in Table 5 and Table 6, it can be seen that the test panels 20-24 according to the present disclosure have significantly improved the elongation at break for aged panels, providing a reduction in aged embrittlement.

Table 7 provides flexural strength data for aged test panels of Derakane epoxy vinyl ester resin having the stated ratios of resin to glass fibre (in brackets) wherein the glass fibre is treated with a monomer deficient resin. Test panel 25 is uncoated and panels 26 to 28 are coated. Panels having the coated glass fibre show significantly improved toughness.

Composite Flexural Modulus (GPa) Flexural Stress at Yield (MPa) Elongation at Break (%) Test Panel 25 (2.3:1) 6.20 124 0.87 Test Panel 26 (5:1) 3.80 120 4.0 Test Panel 27 (5:1) 3.50 115 4.0 Test Panel 28 (5:1) 3.60 118 4.0

Table 7: Flexural strength data for aged test panels of Derakane 411-350 epoxy vinyl ester resin having a polymer treated glass wherein the polymer is a monomer deficient resin.

INDUSTRIAL APPLICABILITY

The present disclosure is useful in a wide variety of industries, including: construction, automotive, aerospace, marine and for corrosion resistant products. The reinforced composite material of the disclosure may provides improved long-term mechanical properties compared to traditional glass fibre reinforced materials. Although the disclosure has been described with reference to specific examples, it will be appreciated by those skilled in the art that the disclosure may be embodied in many other forms.

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In the claims which follow and in the preceding description, except where the context requires otherwise due to express language or necessary implication, the word comprise or variations such as comprises or comprising is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the moulded composite material.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

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1. A moulded composite material, comprising a cured reinforced composite material, wherein the cured reinforced composite material comprises at least one cured resin having:

5 i) a polymer to produce a polymer-modified resin; and ii) a plurality of reinforcing fibres coated with a coupling agent, the cured resin adjacent to said reinforcing fibres defining an interphase, wherein the coated plurality of reinforcing fibres are treated such that the properties of said interphase are substantially equivalent to those of the bulk cured resin.

2. The moulded composite material of claim 1, wherein the at least one cured resin has between 5 to 50 % w/w of the polymer to produce a polymer-modified resin.

3. The moulded composite material of claim 1 or claim 2, wherein the cured resin has

15 flexural toughness greater than about 3 Joules when tested in a standard flexure test, the test piece having dimensions about 100 mm in length, 15 mm in width and 5 mm in thickness.

4. The moulded composite material of any one of claims 1-3, wherein the treatment is a polymeric coating and/or a hydrophilic surface coating applied to said coated plurality of

2 0 reinforcing fibres.

5. The moulded composite material of claim 4, wherein:

i) the polymer of said polymeric coating is a monomer deficient low activity unsaturated polyester resin; or

2 5 ii) the hydrophilic surface coating is prepared by reacting a vinyl functional silane with a polyol.

6. The moulded composite material of any one of claims 1-5, wherein the coupling agent is a vinyl functional silane.

7. The moulded composite material of any one of claims 1-6, wherein the reinforcing fibre of the plurality of reinforcing fibres is a glass fibre.

2016216529 18 May 2018

8. The moulded composite material of any one of claims 1-7, wherein the curable resin is chosen or modified with said polymer to have predetermined properties.

9. The moulded composite material of any one of claims 1-8, wherein the properties are 5 chosen from one or more of tear resistance, strength, toughness and resistance to embrittlement.

10. The moulded composite material of any one of claims 1-9, wherein the unsaturated polyester resin is provided by reacting a polyol with an acid;

10 wherein:

i) the polyol comprises propylene glycol, methyl propanediol, neopentyl glycol, or diethyleneglycol;

ii) the acid comprises terephthalic acid, isophthalic acid, fumaric acid, or 1,4cyclohexane diacid; and

15 iii) the unsaturated polyester resin comprises a saturated to unsaturated acid ratio of between about 1.2:1 to 2:1.

11. The moulded composite material of any one of claims 1-10, wherein the treatment:

i) reduces catalysation of resin polymerisation in the interphase when compared to a

2 0 fibre not treated; or ii) reduces embrittlement of said interphase when compared to a fibre not treated.
12. A moulded composite material, comprising a cured reinforced composite material, wherein the cured reinforced composite material comprises:

2 5 i) a plurality of hydrophilic surface-modified reinforcing glass fibres, wherein the hydrophilic surface-modified reinforcing glass fibre comprises a reinforcing glass fibre modified with a hydrophilic surface coating comprising:

a) a first coating of a vinyl functional silane coupling agent; and

b) a second coating of the product of a vinyl functional silane coupling agent

3 0 reacted with a polyol;

ii) at least one cured polyester resin; and iii) at least one interphase defined by the at least one cured polyester resin adjacent to the at least one hydrophilic surface-modified reinforcing glass fibre of the plurality of hydrophilic surface-modified reinforcing glass fibres;

2016216529 18 May 2018 wherein the at least one interphase has one or more properties substantially equivalent to those of the bulk at least one cured polyester resin, selected from the group consisting of: strength, flexural toughness, brittleness, density, cross-link density, chemical resistance, molecular weight, or degree of crystallinity, or a combination thereof.
13. The moulded composite material of claim 12, wherein the at least one cured polyester resin is an at least one cured unsaturated polyester resin.
14. The moulded composite material of claim 12 or claim 13, wherein the at least one cured 10 polyester resin is an at least one cured hydrophilic, unsaturated polyester resin.
15. The moulded composite material of any one of claims 12-14, wherein the polyester of said at least one cured polyester resin has less than 33% w/w of monomer content.

15
16. The moulded composite material of any one of claims 12-15, wherein the polyester resin is provided by reacting a polyol with an acid, wherein:

i) the polyol comprises propylene glycol, methyl propanediol, neopentyl glycol, or diethyleneglycol;

ii) the acid comprises terephthalic acid, isophthalic acid, fumaric acid, or 1,42 0 cyclohexane diacid; and iii) the unsaturated polyester resin comprises a saturated to unsaturated acid ratio of between 1.2:1 to 2:1.
17. The moulded composite material of any one of claims 12-16, wherein the at least one 2 5 cured polyester resin has flexural toughness greater than 3 Joules when tested in a standard flexure test, the test piece having dimensions 100 mm in length, 15 mm in width and 5 mm in thickness.
18. The moulded composite material of claim 1-17, wherein the monomer content of said 30 polyester is between 5 to 30 % w/w.
19. The moulded composite material of any one of claims 1-18, wherein the vinyl functional silane coupling agent is selected from the group consisting of Dow Coming Z-6030 (methacryloxypropyl-trimethoxysilane), Z-6032 (vinylbenzylaminoethylaminopropyl35 trimethoxysilane), and Z-6075 (vinyl-tris(acetoxy) silane).

2016216529 18 May 2018
20. The moulded composite material of any one of claims 1-19, wherein the cured reinforced composite material has flexural toughness greater than 3 Joules for up to 5 years.

5
21. The moulded composite material of any one of claims 1 -20, wherein the hydrophilic surface-modification of the reinforcing glass fibres:

a) reduces catalysation of resin polymerisation in the interphase when compared to a fibre not treated; or

b) reduces embrittlement of said interphase when compared to a fibre not treated.
22. A moulded composite material, comprising:

i) a plurality of reinforcing fibers treated with a hydrophilic surface coating comprising the product of a vinyl functional silane coupling agent reacted with a polyol;

ii) at least one cured resin; and

15 iii) at least one interphase defined by the at least one cured resin adjacent to and substantially surrounding at least one reinforced fiber of the plurality of reinforcing fibers;

wherein the hydrophilic surface coating of said plurality of reinforcing fibers results in the at least one interphase having one or more properties substantially equivalent to those of the

2 0 bulk cured resin.
23. The moulded composite material of claim 22, wherein:

a) the coupling agent comprises methacryloxypropyl-trimethoxysilane, vinylbenzylaminoethylaminopropyl-trimethoxysilane, or vinyl-tris(acetoxy) silane;

2 5 and

b) the polyol comprises a tri-hydroxy compound or a tetra-hydroxy compound.
24. The moulded composite material of claim 23, wherein the tri-hydroxy compound is trimethylolpropane and/or the tetra-hydroxy compound is pentaerythritol.
25. The moulded composite material of any one of claims 1-24, wherein the one or more properties of said at least one interphase comprises:

i) a mechanical property, comprising strength, toughness, or brittleness; or ii) a physical or chemical property, comprising density, cross-link density, chemical

3 5 resistance, molecular weight, or degree of crystallinity.

2016216529 18 May 2018
26. The moulded composite material of any one of claims 22-25, wherein the at least one cured resin is a polymer-modified resin.

5
27. The moulded composite material of claim 26, wherein the polymer-modified resin comprises between 5 to 50 % w/w of the polymer.
28. The moulded composite material of any one of claims 22-27, wherein the polymermodified resin has one or more of the following properties: tear resistance, strength,

10 toughness, or resistance to embrittlement.
29. The moulded composite material of any one of claims 22-28, wherein the polymermodified resin has flexural toughness greater than 3 Joules according to a standard flexure test using a test piece of 100 mm length, 15 mm width, and 5 mm thickness.
30. The moulded composite material of any one of claims 22-29, wherein the hydrophilic surface coating of the plurality of reinforcing fibers:

a) reduces catalyzation of resin polymerization in the at least one interphase when compared to an untreated fiber; or

2 0 b) reduces embrittlement of said at least one interphase when compared to an untreated fiber.
31. The moulded composite material of any one of claims 1-30, wherein the reinforcing fiber of the plurality of reinforcing fibers has a length of between 100 and 1000 microns.
32. The moulded composite material of any one of claims 1-31, wherein the flexural toughness is greater than 3 Joules for up to 5 years.
33. The moulded composite material of any one of claims 1-32, wherein the reinforced

3 0 composite material comprises one or more of the following:

i) a flexural modulus of greater than about 3.1 GPa;

ii) a flexural stress of greater than about 120 MPa; or iii) an elongation at break of greater than about 2%.

2016216529 18 May 2018
34. The moulded composite material of claim 33, wherein the flexural modulus is greater than about 3.5 GPa.