WO2018011349A1

WO2018011349A1 - Polyester composition

Info

Publication number: WO2018011349A1
Application number: PCT/EP2017/067718
Authority: WO
Inventors: Michael Greenhill-Hooper; Michael Schmidt; Mark Murphy
Original assignee: Imerys Talc Europe
Current assignee: Imerys Talc Europe
Priority date: 2016-07-13
Filing date: 2017-07-13
Publication date: 2018-01-18
Anticipated expiration: 2019-01-13

Abstract

A composition comprising a polyester, titanium dioxide and a mineral filler, a bilayer comprising a first layer comprising a black dye or pigment and a second layer comprising said polyester compositionand a container formed said bilayeror from a sheet of said polyester composition.

Description

POLYESTER COMPOSITION TECHNICAL FIELD The present invention relates generally to compositions comprising polyester (e.g. polyethylene terephthalate (PET) or polybutylene terephthalate (PBT)), titanium dioxide and a mineral filler. The present invention further relates to a bilayer, wherein one of the layers comprises or consists of a composition comprising polyester (e.g. PET or PBT), titanium dioxide and a mineral filler. The other layer of the bilayer may, for example, comprise a black dye or pigment such as carbon black. The present invention also relates to containers made from said compositions and bilayers. The layer comprising a black dye or pigment may, for example, be present on the inside of the container. BACKGROUND

Polymers such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) may be used to make packaging, in particular packaging for foodstuffs such as UHT milk. Polyesters such as PET and PBT are advantageous in that they provide a good gas barrier and can be used in relatively small amounts to reduce waste. The properties of the polymer may be influenced by combining it with various additives. Particular additives may be selected in order to obtain a polymer composition having desired properties, for example a desired colour and/or opacity. This may, for example affect the suitability of the composition for use in packaging of a particular product. For example, it is desirable to reduce light transmission through milk packaging for preservation of the milk. For example, in certain applications, it may be desirable to provide packaging with a white outer layer. It may be desirable to provide a composition suitable for different methods of packaging production, in particular the production of plastic containers. It is thus desirable to provide alternative or improved polyester compositions.

SUMMARY

In accordance with a first aspect of the present invention there is provided a composition comprising a polyester, titanium dioxide and a mineral filler. In certain embodiments, the ratio of the titanium dioxide to the mineral filler is equal to or greater than about 1 :1 . In certain embodiments, the ratio of titanium dioxide to the mineral filler is equal to or less than about 5:1 . Thus, in accordance with a further aspect of the present invention there is provided a composition comprising polyester, titanium dioxide and a mineral filler, wherein the ratio of the titanium dioxide to the mineral filler is equal to or greater than about 1 :1 and equal to or less than about 5:1.

In accordance with a second aspect of the present invention there is provided a composition comprising a polyester, titanium dioxide, a mineral filler and a black dye or pigment. In certain embodiments the black dye or pigment is carbon black. Thus, in accordance with a further aspect of the present invention there is provided a composition comprising a polyester, titanium dioxide, a mineral filler and carbon black.

In accordance with a further aspect of the present invention there is provided a composition comprising a polymer, titanium dioxide and a mineral filler. In certain embodiments, the polymer is styrene butadiene compound (SBC), polystyrene (e.g. high impact polystyrene) and/or polybutylene terephthalate (PBT). Thus, in accordance with a further aspect of the present invention there is provided a composition comprising a polymer selected from styrene butadiene compound (SBC), polystyrene (e.g. high impact polystyrene) and/or polybutylene terephthalate, titanium dioxide and a mineral filler. In certain embodiments, the ratio of the titanium dioxide to the mineral filler is as described for the other aspects and embodiments disclosed herein. In certain embodiments, the composition further comprises a black dye or pigment such as carbon black. In certain embodiments, the composition is a masterbatch composition. In certain embodiments, the composition can be further combined with a polyester compound (e.g. polyethylene terephthalate), for example during a compounding step.

In accordance with a third aspect of the present invention there is provided a bilayer comprising or consisting of at least one layer comprising a polymer or polyester composition in accordance with any aspect or embodiment of the present invention.

In certain embodiments, the bilayer comprises a first layer comprising a black dye or pigment and a second layer comprising polyester (e.g. PET or PBT), titanium dioxide and a mineral filler. The first and/or second layers may, for example, comprise a composition in accordance with any aspect or embodiment of the present invention. In certain embodiments, the first layer has a L^* whiteness equal to or less than about 20. In certain embodiments, the first layer comprises a polymer. In certain embodiments, the first layer comprises polyester (e.g. PET or PBT). In certain embodiments, the second layer comprising polyester (e.g. PET or PBT), titanium dioxide and a mineral filler does not comprise a black dye or pigment. In certain embodiments, the first layer is identical to the second layer except that it further comprises a black dye or pigment.

In accordance with a fourth aspect of the present invention there is provided a container formed from a composition according to any aspect or embodiment of the present invention. In accordance with a fifth aspect of the present invention there is provided a container formed from a bilayer according to any aspect or embodiment of the present invention. In certain embodiments, the layer comprising a black dye or pigment faces the inside of the container. In accordance with a sixth aspect of the present invention there is provided a method of making a composition in accordance with any aspect or embodiment of the present invention, the method comprising combining the polymer (e.g. polyester), titanium dioxide and mineral filler. In accordance with a seventh aspect of the present invention there is provided a method of making a bilayer in accordance with any aspect or embodiment of the present invention, the method comprising joining a layer comprising a polymer (e.g. polyester) composition in accordance with any aspect or embodiment of the present invention to another layer. In certain embodiments, one layer comprises a black dye or pigment and the other layer comprises polyester, titanium dioxide and a mineral filler. In certain embodiments, one layer comprises a black dye or pigment and the other layer does not comprise a black dye or pigment.

In accordance with an eighth aspect of the present invention there is provided a method of making a container in accordance with any aspect or embodiment of the present invention, the method comprises shaping a composition or bilayer in accordance with any aspect or embodiment of the present invention into a container.

In accordance with a ninth aspect of the present invention there is provided a use of a composition or bilayer in accordance with any aspect or embodiment of the present invention to form a container. In accordance with a tenth aspect of the present invention there is provided a use of a container in accordance with any aspect or embodiment of the present invention to package a foodstuff such as milk (e.g. UHT milk). In certain embodiments of any aspect of the present invention the polyester is polyethylene terephthalate (PET).

In certain embodiments of any aspect of the present invention the polyester is polybutylene terephthalate (PBT).

In certain embodiments of any aspect of the present invention the titanium dioxide is rutile.

In certain embodiments of any aspect of the present invention the mineral filler is a phyllosilicate. In certain embodiments, the mineral filler is kaolin and/or talc. In certain embodiments, the mineral filler is talc.

In certain embodiments of any aspect of the present invention the mineral filler is surface-treated with a hydrophilic polymer. In certain embodiments the hydrophilic polymer is polyethylene glycol (PEG) or polyether siloxane.

In certain embodiments of any aspect of the present invention the ratio of titanium dioxide to the mineral filler is equal to or greater than about 1 :1 . In certain embodiments, the ratio of titanium dioxide to the mineral filler is equal to or less than about 5:1 . In certain embodiments, the ratio of titanium dioxide to the mineral filler is equal to or less than about 3:1 . In certain embodiments, the ratio of titanium dioxide to the mineral filler is equal to or greater than 1 :1 and equal to or less than 2:1 . In certain embodiments, the ratio of titanium dioxide to the mineral filler is about 3:2. In certain embodiments of any aspect of the present invention the mineral filler has a moisture content equal to or less than about 1 wt%.

In certain embodiments of any aspect of the present invention the mineral filler has a L^* whiteness equal to or greater than about 90. In certain embodiments, the mineral filler has a L^* whiteness equal to or greater than about 94. In certain embodiments of any aspect of the present invention the mineral filler has a b^* yellowness ranging from about -1 .5 to about 4. In certain embodiments, the mineral filler has a b^* yellowness ranging from about -1.5 to about 2. In certain embodiments, the mineral filler has a b^* yellowness ranging from about 0.5 to about 2. In certain embodiments the mineral filler has a b^* yellowness ranging from about 0.5 to about 1 .5.

In certain embodiments of any aspect of the present invention the mineral filler has a Y(D65) equal to or greater than about 85 %. In certain embodiments, the mineral filler has a Y(D65) equal to or greater than about 90 %. In certain embodiments, the mineral filler has a Y(D65) equal to or greater than about 92 %.

In certain embodiments of any aspect of the present invention the mineral filler has a dso equal to or less than about 2.5 μηη. In certain embodiments, the mineral filler has a dso equal to or less than about 0.2 μηι.

In certain embodiments of any aspect of the present invention the mineral filler has a dg5 equal to or less than about 8 μηη. In certain embodiments, the mineral filler has a dg5 equal to or less than about 5 μηι. In certain embodiments, the polyester composition has a L^* whiteness equal to or greater than about 85 when it is in the form of a sheet having a thickness of 0.3 mm or less. In certain embodiments, the polyester composition has a L^* whiteness equal to or greater than about 88 when it is in the form of a sheet having a thickness of 0.3 mm or less. In certain embodiments, the polyester composition has a L^* whiteness equal to or greater than about 90 when it is in the form of a sheet having a thickness of 0.3 mm or less. In certain embodiments the polyester composition has a L^* whiteness equal to or greater than about 92 when it is in the form of a sheet having a thickness of 0.3 mm or less. In certain embodiments, the polyester composition has a b^* yellowness equal to or less than about 6 when it is in the form of a sheet having a thickness of 0.3 mm or less. In certain embodiments, the polyester composition has a b^* yellowness from about -1 .5 to about 6 when it is in the form of a sheet having a thickness of 0.3 mm or less. In certain embodiments, the polyester composition has a b^* yellowness from about -1 .5 to about 4 when it is in the form of a sheet having a thickness of 0.3 mm or less. In certain embodiments, the polyester composition has a b^* yellowness from about -0.5 to about 2 when it is in the form of a sheet having a thickness of 0.3 mm or less. In certain embodiments, the polyester composition has a b^* yellowness from about -0.5 to about 1 when it is in the form of a sheet having a thickness of 0.3 mm or less. In certain embodiments, the polyester composition has a Y(D65) equal to or greater than about 70 % when it is in the form of a sheet having a thickness of 0.3 mm or less. In certain embodiments, the polyester composition has a Y(D65) equal to or greater than about 74 % when it is in the form of a sheet having a thickness of 0.3 mm or less. In certain embodiments, the polyester composition has a Y(D65) equal to or greater than about 76 % when it is in the form of a sheet having a thickness of 0.3 mm or less. In certain embodiments, the polyester composition has a Y(D65) equal to or greater than about 78 % when it is in the form of a sheet having a thickness of 0.3 mm or less. In certain embodiments, the polyester composition has a Y(D65) equal to or greater than about 79 % when it is in the form of a sheet having a thickness of 0.3 mm or less. In certain embodiments, the polyester composition has a Y(D65) equal to or greater than about 80 % when it is in the form of a sheet having a thickness of 0.3 mm or less. In certain embodiments, the polyester composition has a Y(D65) equal to or greater than about 85 % when it is in the form of a sheet having a thickness of 0.3 mm or less. In certain embodiments, the polyester composition has a % light transmission at 600 nm equal to or less than about 25% when it is in the form of a sheet having a thickness of 0.3 mm or less.

In certain embodiments, the polyester composition has a % light transmission at 500 nm equal to or less than about 15% when it is in the form of a sheet having a thickness of 0.3 mm or less.

In certain embodiments, the polyester composition is a masterbatch. In certain embodiments, the composition comprises equal to or greater than about 50 wt% total titanium dioxide and mineral filler, alternatively equal to or greater than about 55 wt% total titanium dioxide and mineral filler. In certain embodiments, the composition comprises equal to or greater than about 60 wt% total titanium dioxide and mineral filler. In certain embodiments, the polyester composition is in the form of a sheet having a thickness equal to or less than about 0.5 mm. In certain embodiments, the sheet has a thickness equal to or less than about 0.3 mm. In certain embodiments, the sheet comprises equal to or greater than about 5 wt% total titanium dioxide and mineral filler. In certain embodiments, the sheet comprises from about 5 wt% to about 20 wt% total titanium dioxide and mineral filler. In certain embodiments, the sheet comprises from about 5 wt% to about 10 wt% total titanium dioxide and mineral filler.

In certain embodiments, the polyester sheet has a L^* whiteness equal to or greater than about 88. In certain embodiments, the polyester sheet has a L^* whiteness equal to or greater than about 90. In certain embodiments, the polyester sheet has a L^* whiteness equal to or greater than about 92.

In certain embodiments, the polyester sheet has a b^* yellowness equal to or less than about 6. In certain embodiments, the polyester sheet has a b^* yellowness from about - 1 .5 to about 6, alternatively from about -1 .5 to about 4, alternatively from about -0.5 to about 2, alternatively from about -0.5 to about 1 .

In certain embodiments, the polyester sheet has a Y(D65) equal to or greater than about 70 %, alternatively equal to or greater than about 74 %, alternatively equal to or greater than about 76 %, alternatively equal to or greater than about 78 %, alternatively equal to or greater than about 79 %, alternatively equal to or greater than about 80 %. In certain embodiments, the polyester sheet has a Y(D65) equal to or greater than about 85 %.

In certain embodiments, the polyester sheet has a gloss at 60° that is equal to or greater than about 65 %. In certain embodiments, the polyester sheet has a gloss at 60° that is equal to or greater than about 70 %.

In certain embodiments, the polyester sheet has a % light transmission at 600 nm equal to or less than about 25%. In certain embodiments, the bilayer has a % light transmission at 600 nm equal to or less than about 1 %.

In certain embodiments, the polyester sheet has a % light transmission at 500 nm equal to or less than about 15%. In certain embodiments, the bilayer has a thickness of 0.5 mm or less. Certain embodiments of the present invention may provide one or more of the following advantages:

• Desired light transmission through the sheet or bilayer;

· Desired gloss;

• Desired colour (e.g. desired whiteness).

In addition, the compositions of the invention are particularly suitable for different methods of packaging production, in particular the production of plastic containers.

Different processes are typically used. Containers are generally manufactured by extrusion blow moulding. In extrusion blow moulding the material is melted down and extruded into a hollow tube or parison, before being clamped into a mould and subjected to internal pressure to form the shape of the finished container. Extrusion blow moulding provides a cheap, simple and rapid process for forming plastics containers, including those with complex shapes.

Another method of manufacturing plastics containers such as bottles is two-stage injection stretch blow moulding. In this process the plastic material is melted down and then injection moulded to form a preform including a finished neck or mouth and a body portion arranged to be subsequently expanded and moulded into a desired shape. The preform is then cooled (or allowed to cool) to ambient temperature, and may be transported to a different location, before being reheated, stretched by a stretch rod, and subjected to internal pressure while clamped in a container mould to form the shape of the finished container.

However, many materials are not suitable for this type of process, and can also suffer from bad optical properties or visual defect, which would be unacceptable for the consumer.

The compositions of the invention are all suitable for the processes of manufacture of plastic containers, in particular to the two-stage injection stretch blow moulding process and the extrusion blow moulding process. The details, examples and preferences provided in relation to any particular one or more of the stated aspects of the present invention apply equally to all aspects of the present invention. Any combination of the embodiments, examples and preferences described herein in all possible variations thereof is encompassed by the present invention unless otherwise indicated herein, or otherwise clearly contradicted by context.

DETAILED DESCRIPTION

Compositions There is provided herein a composition comprising a polyester such as polyethylene terephthalate (PET) or polybutylene terephthalate (PBT), titanium dioxide and a mineral filler. There is also provided herein a composition comprising a polymer, titanium dioxide and a mineral filler. A composition comprising a polymer other than PET or another polyester may, for example, be a masterbatch composition. This masterbatch composition may further be combined with PET or another polyester, and this composition may for example, be used to make the bilayers and articles (e.g. containers) disclosed herein. In certain embodiments, the masterbatch compositions may be combined with PET or another polyester, and a black dye or pigment, to make a first layer of the bilayer disclosed herein and/or another masterbatch composition is combined with PET or another polyester to make a second layer of the bilayer disclosed herein.

The ratio of the titanium dioxide to the mineral filler may be equal to or greater than about 1 :1 . For example, the ratio of the titanium dioxide to the mineral filler may be equal to or greater than about 1 .1 :1 or equal to or greater than about 1 .2:1 or equal to or greater than about 1 .3:1 or equal to or greater than about 1 .4:1 or equal to or greater than about 1 .5:1 . For example, the ratio of the titanium dioxide to the mineral filler may be equal to or less than about 5:1 or equal to or less than about 4.5:1 or equal to or less than about 4:1 or equal to or less than about 3.5:1 or equal to or less than about 3:1 or equal to or less than about 2.5:1 or equal to or less than about 2:1 . For example, the ratio of the titanium dioxide to the mineral filler may range from about 1 :1 to about 5:1 or from about 1 : 1 to about 3:1 or from about 1 :1 to about 2:1. For example, the ratio of the titanium dioxide to the mineral filler may be about 3:2. The composition may, for example, be a masterbatch composition. A masterbatch composition is a composition comprising a high concentration of the titanium dioxide, mineral filler and any other pigments or additives that may or may not be present in a carrier polymer. Masterbatch compositions are generally cooled and cut into a granular shape. The masterbatch can then be stored and/or transported before incorporation into a final polymer composition (for example comprising the same polymer as the carrier polymer in the masterbatch composition). The masterbatch composition generally enables the minerals, pigments and additives to be evenly dispersed in the final polymer composition.

The masterbatch composition may, for example, comprise equal to or greater than about 50 wt% total titanium dioxide and mineral filler. For example, the masterbatch may comprise equal to or greater than about 55 wt% or equal to or greater than about 60 wt% or equal to or greater than about 65 wt% or equal to or greater than about 70 wt% or equal to or greater than about 75 wt% or equal to or greater than about 80 wt% total titanium dioxide and mineral filler. The masterbatch composition may, for example, comprise up to about 80 wt% or up to about 70 wt% or up to about 60 wt% total titanium dioxide and mineral filler.

The composition may, for example, be a final polymer composition (in a suitable form for its end use). The composition may, for example, comprise from about 1 wt% to about 20 wt% total titanium dioxide and mineral filler. For example, the composition may comprise from about 2 wt% to about 20 wt% or from about 3 wt% to about 20 wt% or from about 4 wt% to about 20 wt% or from about 5 wt% to about 20 wt% total titanium dioxide and mineral filler. The composition may, for example, comprise from about 5 wt% to about 15 wt% or from about 5 wt% to about 10 wt% total titanium dioxide and mineral filler.

The composition may, for example, be in the form of a sheet. A sheet is a continuous polymeric material that may be relatively thin in comparison to its surface area. The sheet may also be referred to as a film or membrane. The sheet may, for example, be monoaxially oriented or biaxially oriented.

The sheet may, for example, have a thickness equal to or less than about 0.5 mm. For example, the sheet may have a thickness equal to or less than about 0.4 mm or equal to or less than about 0.3 mm or equal to or less than about 0.2 mm. For example, the sheet may have a thickness equal to or greater than about 0.01 mm or equal to or greater than about 0.05 mm or equal to or greater than about 0.1 mm. The thickness may be measured using a thickness gauge.

The sheet may, for example, have a L^* whiteness equal to or greater than about 85. For example, the sheet may have a L^* whiteness equal to or greater than about 86 or equal to or greater than about 87 or equal to or greater than about 88. The sheet may, for example, have a L^* whiteness equal to or greater than about 90. For example, the sheet may have a L^* whiteness equal to or greater than about 90.5 or equal to or greater than about 91 or equal to or greater than about 91 .5 or equal to or greater than about 92 or equal to or greater than about 92.5 or equal to or greater than about 93 or equal to or greater than about 93.5 or equal to or greater than about 94. The sheet may, for example, have a L^* whiteness equal to or less than about 100 or equal to or less than about 99 or equal to or less than about 98. The sheet may, for example, have a b^* yellowness equal to or less than about 6. For example, the sheet may have a b^* yellowness equal to or less than about 5.5 or equal to or less than about 5 or equal to or less than about 4.5 or equal to or less than about 4 or equal to or less than about 3.5 or equal to or less than about 3. The sheet may, for example, have a b^* yellowness equal to or greater than about -5. For example, the sheet may have a b^* yellowness equal to or greater than about -4 or equal to or greater than about -3 or equal to or greater than about -2 or equal to or greater than about -1.5 or equal to or greater than about -1 or equal to or greater than about -0.5 or equal to or greater than about -0.1 or equal to or greater than about 0. For example, the sheet may have a b^* yellowness ranging from about -5 to about 6 or from about -2 to about 5 or from about 0 to about 5.

The sheet may, for example, have a Y(D65) equal to or greater than about 70 %. For example, the sheet may have a Y(D65) equal to or greater than about 72 % or equal to or greater than about 74 % or equal to or greater than about 75 % or equal to or greater than about 76 % or equal to or greater than about 78 % or equal to or greater than about 80 % or equal to or greater than about 82 % or equal to or greater than about 84 %. The sheet may, for example, have a Y(D65) equal to or greater than about 85 %. For example, the sheet may have a Y(D65) equal to or greater than about 86 % or equal to or greater than about 87 % or equal to or greater than about 88 % or equal to or greater than about 89 % or equal to or greater than about 90 % or equal to or greater than about 91 % or equal to or greater than about 92 % or equal to or greater than about 93 % or equal to or greater than about 94 % or equal to or greater than about 95 %. The sheet may, for example, have a Y(D65) up to about 100 % or up to about 99 % or up to about 98 %. The composition may, for example, have a L^* whiteness equal to or greater than about 85 when it is in the form of a sheet having a thickness of 0.3 mm or less. For example, the composition may have a L^* whiteness equal to or greater than about 86 or equal to or greater than about 87 or equal to or greater than about 88 when it is in the form of a sheet having a thickness of 0.3 mm or less. The composition may, for example, have a L^* whiteness equal to or greater than about 90 when it is in the form of a sheet having a thickness of 0.3 mm or less. For example, the composition may have a L^* whiteness equal to or greater than about 90.5 or equal to or greater than about 91 or equal to or greater than about 91 .5 or equal to or greater than about 92 or equal to or greater than about 92.5 or equal to or greater than about 93 or equal to or greater than about 93.5 or equal to or greater than about 94 when it is in the form of a sheet having a thickness of 0.3 mm or less. The composition may, for example, have a L^* whiteness equal to or less than about 100 or equal to or less than about 99 or equal to or less than about 98 when it is in the form of a sheet having a thickness of 0.3 mm or less. The composition may, for example, have a b^* yellowness equal to or less than about 6 when it is in the form of a sheet having a thickness of 0.3 mm or less. For example, the composition may have a b^* yellowness equal to or less than about 5.5 or equal to or less than about 5 or equal to or less than about 4.5 or equal to or less than about 4 or equal to or less than about 3.5 or equal to or less than about 3 when it is in the form of a sheet having a thickness of 0.3 mm or less. The composition may, for example, have a b^* yellowness equal to or greater than about -4 or equal to or greater than about -3 or equal to or greater than about -2 or equal to or greater than about -1 .5 or equal to or greater than about -1 or equal to or greater than about -0.5 or equal to or greater than about -0.1 or equal to or greater than about 0 when it is in the form of a sheet having a thickness of 0.3 mm or less. For example, the composition may have a b^* yellowness ranging from about -5 to about 6 or from about -2 to about 5 or from about 0 to about 5 when it is in the form of a sheet having a thickness of 0.3 mm or less.

The composition may, for example, have a Y(D65) equal to or greater than about 70 % when it is in the form of a sheet having a thickness of 0.3 mm or less. For example, the composition may have a Y(D65) equal to or greater than about 72 % or equal to or greater than about 74 % or equal to or greater than about 75 % or equal to or greater than about 76 % or equal to or greater than about 78 % or equal to or greater than about 80 % or equal to or greater than about 82 % or equal to or greater than about 84 % when it is in the form of a sheet having a thickness of 0.3 mm or less. The composition may, for example, have a Y(D65) equal to or greater than about 85 % when it is in the form of a sheet having a thickness of 0.3 mm or less. The composition may, for example, have a Y(D65) equal to or greater than about 86 % or equal to or greater than about 87 % or equal to or greater than about 88 % or equal to or greater than about 89 % or equal to or greater than about 90 % or equal to or greater than about 91 % or equal to or greater than about 92 % or equal to or greater than about 93 % or equal to or greater than about 94 % or equal to or greater than about 95 % when it is in the form of a sheet having a thickness of 0.3 mm or less.

L^* whiteness and b^* yellowness are determined using the L^*a^*b^* colour space. Y(D65) refers to the light reflection intensity at 550 nm. D65 refers to the light source (daylight). Y(D65) is also determined using the L^*a^*b^* colour space and may be referred to as whiteness (Minolta CR300, illuminant D65/2°)Y. L^* whiteness and b^* yellowness of the sheet may be measured using the spectrophotometer MINOLTA CM-3700D (illuminant D65/10°) from KONICA/MINOLTA.

The sheet may, for example, have a gloss at 60° equal to or greater than about 65%. For example, the sheet may have a gloss at 60° equal to or greater than about 68 % or equal to or greater than about 70 % or equal to or greater than about 72 % or equal to or greater than about 75 %. The sheet may, for example, have a gloss at 60° equal to or less than about 90 % or equal to or less than about 85 % or equal to or less than about 80 %.

The composition may, for example, have a gloss at 60° equal to or greater than about 65 % when it is in the form of a sheet having a thickness of 0.3 mm or less. For example, the composition may have a gloss at 60° equal to or greater than about 68 % or equal to or greater than about 70 % or equal to or greater than about 72 % or equal to or greater than about 75 % when it is in the form of a sheet having a thickness of 0.3 mm or less. The composition may, for example, have a gloss at 60° equal to or less than about 90 % or equal to or less than about 85 % or equal to or less than about 80 % when it is in the form of a sheet having a thickness of 0.3 mm or less. The gloss at 60° is measured according to ISO 2813 and/or by ASTM D-2457 by applying a film of the composition to be measured to a substrate.

The sheet may, for example, have a light transmission at 600 nm equal to or less than about 25%. For example, the sheet may have a light transmission at 600 nm equal to or less than about 24% or equal to or less than about 23% or equal to or less than about 22% or equal to or less than about 21 % or equal to or less than about 20% or equal to or less than about 19% or equal to or less than about 18% or equal to or less than about 17% or equal to or less than about 16% or equal to or less than about 15%. The sheet may, for example, have a light transmission at 600 nm equal to or greater than about 0% or equal to or greater than about 1 % or equal to or greater than about 2% or equal to or greater than about 3% or equal to or greater than about 4% or equal to or greater than about 5%. The composition may, for example, have a light transmission at 600 nm equal to or less than about 25% when it is in the form of a sheet having a thickness of 0.3 mm or less. For example, the composition may have a light transmission at 600 nm equal to or less than about 24% or equal to or less than about 23% or equal to or less than about 22% or equal to or less than about 21 % or equal to or less than about 20% or equal to or less than about 19% or equal to or less than about 18% or equal to or less than about 17% or equal to or less than about 16% or equal to or less than about 15%% when it is in the form of a sheet having a thickness of 0.3 mm or less. The composition may, for example, have a light transmission at 600 nm equal to or greater than about 0% or equal to or greater than about 1 % or equal to or greater than about 2% or equal to or greater than about 3% or equal to or greater than about 4% or equal to or greater than about 5%% when it is in the form of a sheet having a thickness of 0.3 mm or less.

The composition may, for example, have a light transmission at 500 nm equal to or less than about 15% when it is in the form of a sheet having a thickness of 0.4 mm or less or 0.3 mm or less. For example, the composition may have a light transmission at 500 nm equal to or less than about 14% or equal to or less than about 13% or equal to or less than about 12% or equal to or less than about 1 1 % or equal to or less than about 10% when it is in the form of a sheet having a thickness of 0.4 mm or less or 0.3 mm or less. % light transmission is measured by visible spectroscopy, for example using Perkin Elmer uv/vis spectrophotometer (Lambda 650S).

The polyester may, for example, be selected from polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene terephthalate copolymers and polyethylene naphthalate copolymers, which may, for example, contain at least one crystallization retarding compound or recurring structural units. The crystallization retarding agent retards or slows down crystallization of the polyester so as to form small crystals and preventing spherulitic crystallization. The crystallization retarders may, for example, be difunctional compounds such as diacids and/or diols that may, for example, be added to the monomer mixture before or during polymerization. Hereinafter, the present invention may tend to be discussed in terms of PET. However, the invention should not be construed as being limited as such. The polyethylene terephthalate (PET) comprises polymerized units of the monomer ethylene terephthalate. The monomer may be formed by esterification between terephthalic acid and ethylene glycol or by transesterification between ethylene glycol and dimethyl terephthalate. PET is a polyester. The PET may be in an amorphous or semi-crystalline form. The PET may, for example, have a molecular weight ranging from about 10,000 to about 50,000 or from about 15,000 to about 40,000 or from about 20,000 to about 30,000.

The polybutylene terephthalate (PBT) comprises polymerized units of the monomer butylene terephthalate. The monomer may be formed by esterification between terephthalic acid and butan-2,3-diol or by transesterification between butan-2,3-diol and dimethyl terephthalate. PBT is also a polyester. The PBT may be in an amorphous or semi-crystalline form. The PBT may, for example, have a MVR (Melt Volume Flow rate) at 250°C under 2.16 kg load (ISO 1 133-1 ) from 5 to 300 cm³/10 min, or from 10 to 20 cm³/10min.

The polyester (e.g. PET or PBT) may, for example be a bottle grade polyester (e.g. PET or PBT). For example, the PET or the PBT may have an intrinsic viscosity ranging from about 0.5 to about 1 dl/g (for example about 0.76 dl/g). For example, the PET may have a melting temperature ranging from about 220°C to about 280°C, for example from about 240°C to about 260°C (e.g. about 250°C). The PET may, for example, have an acetaldehyde content equal to or less than about 1 ppm. Diethylene glycol (DEG) is often inherently present in polyesters as it forms during the synthesis by condensation of two ethylene glycol monomers. Polyester synthesis conditions may, for example, be controlled to limit the formation of DEG. The composition may, for example, alternatively or additionally comprise one or more additional polymers. For example, the composition may further comprise one or more of styrene butadiene compound (SBC), polystyrene (e.g. high impact polystyrene), polybutylene terephthalate, polyethylene, polypropylene, polyvinyl chloride, polymethylmethacrylate (PMMA), polyolefins, polyacetal, polycarbonate, polyacrylonitrile, polybutadiene, polystyrene, polyacrylate, epoxy polymers, polyurethanes, polycyclopentadienes, polylactic acid, polyglyconic acid, polycaprolactone, and copolymers thereof. The composition may, for example, not comprise any additional polymers. The composition may, for example, comprise one or more further additives. Examples of useful additives include, but are not limited to, opacifying agents, pigments, colorants, slip agents (for example Erucamide), antioxidants, anti-fog agents, anti-static agents, anti-block agents, moisture barrier additives, gas barrier additives, dispersants, hydrocarbon waxes, stabilizers, co-stabilizers, lubricants, agents to improve tenacity, agents to improve heat-and-form stability, agents to improve processing performance, process aids (for example Polybatch® AMF-705), mould release agents (e.g. fatty acids, zinc, calcium, magnesium, lithium salts of fatty acids, organic phosphate esters, stearic acid, zinc stearate, calcium stearate, magnesium stearate, lithium stearate, calcium oleate, zinc palmiate), antioxidants and plasticizers.

The titanium dioxide (also known as titania or T1O2) may for example, be ilmenite, rutile, anatase, akaogiite or brookite. In certain embodiments, the titanium dioxide is rutile. Rutile may, for example, comprise from about 96 wt% to about 99 wt% titanium dioxide in its ore. For example, rutile may comprise at 98 wt% titanium dioxide in its ore. Titanium dioxide may be produced using methods known to those skilled in the art. For example, ilmenite may be mixed with sulfuric acid to remove the iron oxide group to form synthetic rutile. Another method for the production of synthetic rutile from ilmenite uses the Becher Process. Titanium dioxide (in the form of rutile or synthetic rutile) may be purified by converting to titanium tetrachloride and then distilling and re-oxidizing in pure oxygen or plasma to give titanium dioxide. Aluminium chloride may be added to the process as a rutile promoter. The product may be mostly anatase in its absence. The mineral filler may, for example, be selected from one or more of the following: alkaline earth metal carbonate (for example dolomite, i.e. CaMg(CC>3)2), metal sulphate (for example gypsum), metal silicate, metal oxide (for example iron oxide, chromia, antimony trioxide or silica), metal hydroxide, wollastonite, bauxite, talc (for example, French chalk), mica, zinc oxide (for example, zinc white or Chinese white), titanium dioxide (for example, anatase or rutile), zinc sulphide, calcium carbonate (for example precipitated calcium carbonate (PCC), ground calcium carbonate (GCC), for example obtained from limestone, marble and/or chalk, or surface-modified calcium carbonate), barium sulphate (for example, barite, blanc fixe or process white), alumina hydrate (for example, alumina trihydrate, light alumina hydrate, lake white or transparent white), clay (for example kaolin, calcined kaolin, China clay or bentonite), zeolites and combinations thereof. The mineral filler may be selected from any one or more of the materials listed. The mineral filler may comprise a blend of any combination of the listed materials.

In certain embodiments, the mineral filler comprises, consists essentially of or consists of a phyllosilicate (silicate mineral formed by parallel sheets of silicate tetrahedral with S12O5 ratio). In certain embodiments, the mineral filler is kaolin, talc or a combination thereof. Hereinafter, the present invention may be described in terms of kaolin and/or talc. However, the invention should not be construed as being limited as such.

The mineral filler may comprise, consist essentially of or consist of talc. The term "talc" refers to either a magnesium silicate mineral (e.g. hydrated magnesium silicate), or mineral chlorite (magnesium aluminium silicate), or a mixture thereof, optionally associated with other minerals such as dolomite and/or magnesite. The talc may, for example, be synthetic talc, also known as talcose. The talc particulate may, for example, be obtained from a lamellar talc ore. The talc particulate may, for example, be obtained from a microcrystalline ore. The talc particulate may, for example, be a wet milled talc.

The mineral filler may, for example, comprise, consist of, or consist essentially of kaolin. The term kaolin covers the minerals kaolinite, dickite, nacrite and halloysite. The kaolin may be a platy kaolin or a hyper-platy kaolin. By 'platy' kaolin is meant kaolin having a high shape factor. A platy kaolin has a shape factor from about 20 to less than about 60. A hyper-platy kaolin has a shape factor from about 60 to 100 or greater than 100. "Shape factor", as used herein, is a measure of the ratio of particle diameter to particle thickness for a population of particles of varying size and shape as measured using the electrical conductivity methods, apparatuses, and equations described in U.S. Patent No. 5,576,617, which is incorporated herein by reference in its entirety. As described in the '617 patent, the electrical conductivity of a composition of an aqueous suspension of orientated particles under test is measured as the composition flows through a vessel. Measurements of the electrical conductivity are taken along one direction of the vessel and along another direction of the vessel transverse to the first direction. Using the difference between the two conductivity measurements, the shape factor of the particulate material under test is determined.

Kaolin clay for use in certain embodiments of the present invention may be a processed material derived from a natural source, namely raw natural kaolin clay mineral. The processed kaolin clay may typically contain at least about 50% by weight kaolinite. For example, most commercially processed kaolin clays contain greater than about 75% by weight kaolinite and may contain greater than about 90% by weight, in some cases greater than about 95% by weight of kaolinite.

Kaolin clay used in certain embodiments of the present invention may be prepared from the raw natural kaolin clay mineral by one or more other processes which are well known to those skilled in the art, for example by known refining or beneficiation steps. For example, the clay mineral may be bleached with a reductive bleaching agent, such as sodium hydrosulfite. If sodium hydrosulfite is used, the bleached clay mineral may optionally be dewatered, and optionally washed and again optionally dewatered, after the sodium hydrosulfite bleaching step. The clay mineral may be treated to remove impurities, e. g. by flocculation, flotation, or magnetic separation techniques well known in the art.

The process for preparing the mineral filler for use in certain embodiments of the present invention may include one or more comminution steps, e.g., grinding or milling. Light comminution of a coarse mineral is used to give suitable delamination thereof. The comminution may be carried out by use of beads or granules of a plastic (e.g. nylon), sand or ceramic grinding or milling aid. The coarse mineral may be refined to remove impurities and improve physical properties using well known procedures. The mineral may be treated by a known particle size classification procedure, e.g., screening and centrifuging (or both), to obtain particles having a desired dso value or particle size distribution. The mineral filler may, for example, be surface-treated. For example, the mineral filler may be surface-treated with a hydrophilic polymer. The hydrophilic polymer may, for example, be selected from polyethylene glycol (PEG) and/or polyether siloxane. The mineral filler may be dried prior to inclusion in the polyester (e.g. PET or PBT) composition. The mineral filler may, for example, have a moisture content equal to or less than about 1 wt% or equal to or less than about 0.5wt% or equal to or less than about 0.1 wt% based on the dry weight of the filler. The mineral filler may, for example, have a L^* whiteness equal to or greater than about 90. For example, the mineral filler may have a L^* whiteness equal to or greater than about 90.5 or equal to or greater than about 91 or equal to or greater than about 91 .5 or equal to or greater than about 92 or equal to or greater than about 92.5 or equal to or greater than about 93 or equal to or greater than about 93.5 or equal to or greater than about 94 or equal to or greater than about 94.5 or equal to or greater than about 95 or equal to or greater than about 95.5 or equal to or greater than about 96. For example, the mineral filler may have a L^* whiteness equal to or less than about 100 or equal to or less than about 99 or equal to or less than about 98 or equal to or less than about 97.

The mineral filler may, for example, have a b^* yellowness equal to or less than about 4. For example, the mineral filler may have a b^* yellowness equal to or less than about 3.5 or equal to or less than about 3 or equal to or less than about 2.5 or equal to or less than about 2. For example, the mineral filler may have a b^* yellowness equal to or less than about 1 .9 or equal to or less than about 1 .8 or equal to or less than about 1 .7 or equal to or less than about 1 .6 or equal to or less than about 1 .5 or equal to or less than about 1.4 or equal to or less than about 1 .3 or equal to or less than about 1 .2. For example, the mineral filler may have a b^* yellowness equal to or greater than about - 1 .5 or equal to or greater than about -1 or equal to or greater than about-0.5 or equal to or greater than about 0 or equal to or greater than about 0.5 or equal to or greater than about 0.6 or equal to or greater than about 0.7 or equal to or greater than about 0.8 or equal to or greater than about 0.9 or equal to or greater than about 1. For example, the mineral filler may have a b^* yellowness ranging from about -1 .5 to about 2 or from about 0 to about 2 or from about 0.5 to about 2 or from about 0.5 to about 1 .5. The mineral filler may, for example, have a Y(D65) equal to or greater than about 85 %. For example, the mineral filler may have a Y(D65) equal to or greater than about 86 % or equal to or greater than about 87 % or equal to or greater than about 88 % or equal to or greater than about 89 % or equal to or greater than about 90 % or equal to or greater than about 91 % or equal to or greater than about 92 %. For example, the mineral filler may have a Y(D65) equal to or less than about 100 % or equal to or less than about 99 % or equal to or less than about 98 %.

The L^* whiteness, b^* yellowness and Y(D65) of the mineral filler are measured as described above (the sample preparation is not the same when dealing with a powder rather than a film).

The mineral filler may, for example, have a dso equal to or less than about 2.5 μηη. For example, the mineral filler may have a dso equal to or less than about 2 μηη or equal to or less than about 1 .5 μηη or equal to or less than about 1 μηη or equal to or less than about 0.5 μηη. The mineral filler may, for example, have a dso equal to or greater than about 0.01 μηη or equal to or greater than about 0.05 μηη or equal to or greater than about 0.1 μηη or equal to or greater than about 0.2 μηη or equal to or greater than about 0.5 μηη or equal to or greater than about 1 μηη or equal to or greater than about 1 .5 μηη. The mineral filler may, for example, have a dso ranging from about 0.01 μηη to about 1 μηη or from about 0.05 μηη to about 0.5 μηη or from about 0.1 μηη to about 2.5 μηη or from about 0.1 μηη to about 1 μηη or from about 1 .5 μηη to about 2.5 μηη.

When the mineral filler is talc, the talc may have a dso ranging from about 1 μηη to about 2.5 μηη, for example from about 1 .5 μηη to about 2.5 μηη, for example from about 1.6 μηη to about 2.4 μηη or from about 1 .7 μηη to about 2.3 μηη or from about 1 .8 μηη to about 2.2 μηη or from about 1 .8 μηη to about 2.1 μηη or from about 1 .8 μηη to about 2 μηη. When the mineral filler is talc, the talc may have a dso of about 1 .9 μηη When the mineral filler is kaolin, the kaolin may have a dso ranging from about 0.01 μηη to about 1 μηη, for example from about 0.05 μηη to about 0.7 μηη or from about 0.1 μηη to about 0.5 μηη. When the mineral filler is kaolin, the kaolin may have a dso of about 0.2 μηι. The mineral filler may, for example, have a dgs equal to or less than about 8 μηη. For example, the mineral filler may have a dgs equal to or less than about 7.9 μηη or equal to or less than about 7.8 μηι or equal to or less than about 7.7 μηι or equal to or less than about 7.6 μηι. The mineral filler may, for example, have a dgs equal to or greater than about 0.1 μηη, for example equal to or greater than about 0.5 μηη, for example equal to or greater than about 1 μηη, for example equal to or greater than about 1 .5 μηη or equal to or greater than about 2 μηη or equal to or greater than about 3 μηη or equal to or greater than about 4 μηη or equal to or greater than about 5 μηη or equal to or greater than about 5.5 μηη or equal to or greater than about 6 μηη or equal to or greater than about 6.5 μηη or equal to or greater than about 7 μηη or equal to or greater than about 7.5 μηη. The mineral filler may, for example, have a dgs ranging from about 0.1 μηη to about 8 μηη or from about 0.5 μηη to about 8 μηη or from about 0.1 μηη to about 1 μηη or from about 0.5 μηη to about 1 μηη or from about 1 μηη to about 8 μηη or from about 1 μηη to about 3 μηη or from about 5 μηη to about 8 μηη or from about 6 μηη to about 8 μηη or from about 7 μηη to about 8 μηη. When the mineral filler is talc, the talc may have a dgs ranging from about 3μηι to about 8 μηη or from about 3 μηη to about 5 μηη or from about 6 μηη to about 8 μηη or from about 6.5 μηη to about 8 μηη or from about 7 μηη to about 8 μηη or from about 7 μηη to about 8 μηι. When the mineral filler is kaolin, the kaolin may have a dgs ranging from about 0.1 μηη to about 1 μηη or from about 0.5 μηη to about 1 μηη.

The mineral filler may, for example, have a dio equal to or less than about 1 μηη. For example, the mineral filler may have a dio equal to or less than about 0.9 μηη or equal to or less than about 0.8 μηη or equal to or less than about 0.7 μηη or equal to or less than about 0.6 μηη or equal to or less than about 0.5 μηη or equal to or less than about 0.4 μηη or equal to or less than about 0.3 μηη or equal to or less than about 0.2 μηη or equal to or less than about 0.1 μηη. The mineral filler may, for example, have a dio equal to or greater than about 0.01 μηη or equal to or greater than about 0.05 μηη or equal to or greater than about 0.1 μηη. The mineral filler may, for example, have a dio ranging from about 0.5 μηη to about 1 μηη or from about 0.6 μηη to about 0.9 μηη or from about 0.01 μηη to about 0.2 μηη or from about 0.01 μηη to about 0.1 μηη.

When the mineral filler is talc, the talc may have a dio ranging from about 0.1 μηη to about 1 μηη or from about 0.2 μηη to about 0.8 μηη or from about 0.4 μηη to about 0.7 μηη or from about 0.3 μηη to about 0.6 μιτι. When the mineral filler is kaolin, the kaolin may have a dio ranging from about 0.05 μηι to about 0.5 μηι or from about 0.05 μηι to about 0.2 μηι. Unless otherwise stated, particle size properties referred to herein for the particulate fillers or materials are as measured in a well known manner by sedimentation of the particulate filler or material in a fully dispersed condition in an aqueous medium using a Sedigraph 5100 machine as supplied by Micromeritics Instruments Corporation, Norcross, Georgia, USA (telephone: +17706623620; web-site: www.micromeritics.com), referred to herein as a "Micromeritics Sedigraph 5100 unit". Such a machine provides measurements and a plot of the cumulative percentage by weight of particles having a size, referred to in the art as the 'equivalent spherical diameter' (e.s.d), less than given e.s.d values. The mean particle size dso is the value determined in this way of the particle e.s.d at which there are 50% by weight of the particles which have an equivalent spherical diameter less than that dso value.

In certain embodiments, the composition or sheet further comprises a black dye or pigment. In certain embodiments, the composition or sheet does not comprise a black dye or pigment. The black dye or pigment may, for example, be carbon black. The composition or sheet may, for example, comprise from about 0.1 wt% to about 10 wt% black dye or pigment. For example, the composition or sheet may comprise from about 0.1 wt% to about 5 wt% or from about 0.1 wt% to about 4 wt% or from about 0.1 wt% to about 3 wt% or from about 0.1 wt% to about 2 wt% or from about 0.1 wt% to about 1 wt% of the black dye or pigment. For example, the composition or sheet may comprise from about 0.2 wt% to about 0.5 wt% of the black dye or pigment.

When the composition comprising a black dye or pigment is a masterbatch composition, the composition may comprise from about 2 wt% to about 5 wt% of the black dye or pigment (e.g. carbon black). For example, when the composition comprising a black dye or pigment is a masterbatch composition, the composition may comprise from about 2 wt% to about 3 wt% or from about 2.5 wt% to about 3 wt% of the black dye or pigment (e.g. carbon black). For example, when the composition comprising a black dye or pigment is a masterbatch composition, the composition may comprise about 2.5 wt% of the black dye or pigment (e.g. carbon black). When the composition or sheet comprises a black dye or pigment, the composition may have a L^* whiteness equal to or less than about 20, for example when the composition is in the form of a sheet having a thickness of 0.3 mm or less. When the composition comprises a black dye or pigment, the composition may have a L^* whiteness equal to or less than about 15 or equal to or less than about 10 or equal to or less than about 5 or equal to or less than about 4 or equal to or less than about 3 or equal to or less than about 2, for example when the composition is in the form of a sheet having a thickness of 0.3 mm or less. Bilavers

There is also provided herein a bilayer, wherein at least one of the layers of the bilayer comprises polyester (e.g. polyethylene terephthalate (PET) or polybutylene terephthalate (PBT)), titanium dioxide and a mineral filler. At least one layer of the bilayer may, for example, be a composition or sheet in accordance with any of the aspects or embodiments described herein. At least one layer of the bilayer may, for example, comprise a black dye or pigment. Both layers may, for example, be compositions or sheets in accordance with any of the aspects or embodiments described herein.

In certain embodiments, the bilayer comprises a first layer comprising a black dye or pigment and a second layer comprises polyester (e.g. PET or PBT), titanium dioxide and a mineral filler. In certain embodiments, the second layer does not comprise a black dye or pigment. In certain embodiments, the second layer is in accordance with any of the aspects or embodiments described herein.

In certain embodiments, the first layer comprises a polymer, for example styrene butadiene, polystyrene (e.g. high impact polystyrene), polybutylene terephthalate and/or polyester (e.g. PET). In certain embodiments, the first layer comprises a polymer, wherein at least about 70 wt% or at least about 80 wt% or at least about 90 wt% or at least about 95 wt% of the polymer is amorphous. The amorphous polymer may, for example, be styrene butadiene, polystyrene (e.g. high impact polystyrene) and/or polybutylene terephthalate. In certain embodiments, the first layer comprises titanium dioxide and/or a mineral filler. In certain embodiments, the ratio of titanium dioxide to mineral filler is equal to or greater than about 1 :1 , for example ranging from about 1 :1 to about 5:1 or from about 1 :1 to about 3:1 or from about 1 :1 to about 2:1. In certain embodiments, the first layer comprises polyester (e.g. PET), titanium dioxide and a mineral filler. In certain aspects of the present invention, there is provided a composition comprising a black dye or pigment that can be used to make a first layer of a bilayer as disclosed herein. Thus, in certain aspects of the present invention there is provided a composition comprising a black dye or pigment and a polymer. The polymer may, for example, be an amorphous polymer such as styrene butadiene compound, polystyrene (e.g. high impact polystyrene) and/or polybutylene terephthalate.

In certain embodiments, the first layer has a L^* whiteness equal to or less than about 20. In certain embodiments, the second layer has a L^* whiteness equal to or greater than about 85. In certain embodiments, the second layer has a L^* whiteness equal to or greater than about 90.

In certain embodiments, the first layer is identical to the second layer except that it additionally comprises a black dye or pigment.

In certain embodiments, the bilayer has a thickness of 1 mm or less. For example, the bilayer may have a thickness of 0.9 mm or less or 0.8 mm or less or 0.7 mm or less or 0.6 mm or less or 0.5 mm or less or 0.4 mm or less or 0.3 mm or less. For example, the bilayer may have a thickness equal to or greater than about 0.01 mm or equal to or greater than about 0.05 mm or equal to or greater than about 0.1 mm. In certain embodiments, the bilayer has a light transmission at 600 nm equal to or less than about 1 %. For example, the bilayer may have a light transmission at 600 nm equal to or less than about 0.9 % or equal to or less than about 0.8 % or equal to or less than about 0.7 % or equal to or less than about 0.6 % or equal to or less than about 0.5 %. For example, the bilayer may have a light transmission at 600 nm equal to or greater than about 0 % or equal to or greater than about 0.01 % or equal to or greater than about 0.05 %.

Methods of Making the Compositions and Bilavers The compositions and bilayers described herein may, for example, be made by any method known to those skilled in the art. The compositions described herein may, for example, be made by compounding the polyester (e.g. PET or PBT) with the titanium dioxide, mineral filler and any optional additives. Compounding per se is a technique which is well known to persons skilled in the art of polymer processing and manufacture and consists of preparing plastic formulations by mixing and/or blending polymers and optional additives in a molten state. It is understood in the art that compounding is distinct from blending or mixing processes conducted at temperatures below that at which the constituents become molten. Compounding may, for example, be used to form a masterbatch composition. Compounding may, for example, involve adding a masterbatch composition to a polymer to form a further polymer composition.

The compositions described herein may, for example, be extruded. For example, compounding may be carried out using a screw, e.g. a twin screw, compounder, for example, a Baker Perkins 25 mm twin screw compounder. For example, compounding may be carried out using a multi roll mill, for example a two-roll mill. For example, compounding may be carried out using a co-kneader or internal mixer. The methods disclosed herein may, for example, include compression moulding or injection moulding. The polymer and/or titanium dioxide and/or mineral filler and/or optional additives may be premixed and fed from a single hopper.

The resulting melt may, for example, be cooled, for example, in a water bath, and then pelletized. The resulting melt may be calendared to form a sheet or film. The sheets or films may, for example, be monoaxially oriented or biaxially oriented. In certain embodiments, two separate polymer melts are coextruded to form a bilayer. In certain embodiments, two separate polymer sheets are joined using heat and/or an adhesive material to form a bilayer

The polymer compositions and bilayers described herein may, for example, be shaped into a desired form or article, for example into the form of a container which may be suitable for or intended for holding foodstuff. Shaping of the polymer compositions and bilayers described herein may, for example, involve heating the composition or bilayer to soften it. The polymer compositions and bilayers described herein may, for example, be shaped by molding (e.g. compression molding, injection molding, stretch blow molding, injection blow molding, overmolding, extrusion blow moulding, two-stage injection stretch blow moulding), extrusion, casting, or thermoforming. In certain embodiments, bottle preforms may first be formed, for example using a preform injection over-moulding machine, and then the bottle preforms may be blown into bottles. Uses of the Compositions and Bilayers

The compositions and bilayers described herein may, for example, be used to make containers (packaging). In certain embodiments, the bilayer comprises a layer comprises a black dye or pigment and a layer that does not comprise a black dye or pigment and the layer comprising a black dye or pigment faces the inside of the container and the layer that does not comprise a black dye or pigment faces the outside of the container. In certain embodiments, the layer that does not comprise a black dye or pigment is the outermost layer of the container. In certain embodiments, the container is made solely from a bilayer as described herein.

The containers may, for example, be suitable and/or intended for holding foodstuff. The term foodstuff includes any substance (solid or liquid) capable of being used as a nutrient by an animal, e.g. human. The containers may, for example, be suitable for and/or intended for holding milk, for example UHT milk and/or may be suitable for and/or intended for holding dairy products and/or vitamin drinks. The containers may, for example, be suitable and/or intended for holding biological materials such as blood or urine.

EXAMPLES

Polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) masterbatches comprising 50 to 60 wt% or more total titanium dioxide and mineral filler were prepared using a twin-screw extruder. Masterbatches further comprising about 2.5 wt% carbon black were also successfully prepared. The masterbatches that did not include carbon black were let down to form 0.3 mm polyethylene films using a hot press.

The L^* whiteness, b^* yellowness, Y(D65), gloss at 60° and % light transmission at 600 nm and/or 500 nm of the films were determined as described above. The results are shown in Table 1. Table 1.

The PET used in the films was a food grade PET having an intrinsic viscosity of about 0.76 dl/g, a melting temperature of about 248°C, a water content of less than 50 ppm and an acetaldehyde content less than 1 ppm. Two different types of PBT were used. PBT(1 ) was Pocan® B1501 , available from LanXess Corporation, Cologne, Germany having a melting temperature of about 225°C. PBT(2) was Pocan® KU 1 -7301 , also available from Lanxess Corporation, Cologne, Germany. The titanium dioxide used in the films was a rutile pigment comprising at least 92 wt% T1O2, a density of 3.9 g/cm³ an apparent density of about 50 lb/ft³, a bulk density of 800 kg/cm³ and an oil absorption of 19 g/100g.

Talc A has a dso of 1 .1 μηη, a L^* whiteness of 95.2, a b^* yellowness of -1 .1 1 and a Y(D65) of 92 %.

Talc B has a dso of 1 .9 μηη, a L^* whiteness of 96.4, a b^* yellowness of 1.1 and a Y(D65) of 92 %. Talc C is a polyethylene glycol (PEG) coated talc A.

Kaolin A has a dso of about 0.20 μηη, a L^* whiteness of 96.6 and a b^* yellowness of 3.0 and an ISO brightness of 87.7. Kaolin B is the same as Kaolin A except that it is surface-treated with siloxane or silane (Tegopren™ 6877-45).

Masterbatches further comprising about 2.5 wt% carbon black were also successfully prepared, by the same process except that carbon black (Black Perles® 4750 from Cabot Corporation) was diluted in the polyester resin.

The masterbatches were let down to form polyethylene films using a hot press.

The results are shown in Table 2. Table 2.

The polymer compositions comprising 5 wt% total filler as described in Table 1 above were also successfully blown into 500 ml bottles each weighing approximately 16 g using an overmolding machine. The polymer compositions were overmolded onto a black polymer layer. All compositions had sufficient whiteness to conceal the black layer underneath. The bilayer obtained provides at the same time a good visual for the consumer with a sufficient whiteness and opacity and an excellent protection against light.

The following numbered paragraphs define particular embodiments of the present invention:

1 .A composition comprising polyester, titanium dioxide and a mineral filler, wherein the ratio of the titanium dioxide to the mineral filler is equal to or greater than about 1 :1 and equal to or less than about 5:1.

2. The composition of paragraph 1 , wherein the polyester is polyethylene

terephthalate (PET) or polybutylene terephthalate (PBT).

3. The composition of paragraph 1 or 2, wherein the titanium dioxide is rutile.

4. The composition of any one of paragraphs 1 to 3, wherein the mineral filler is a phyllosilicate.

5. The composition of any one of paragraphs 1 to 4, wherein the mineral filler is kaolin and/or talc.

6. The composition of any one of paragraphs 1 to 5, wherein the mineral filler is surface-treated with a hydrophilic polymer such as polyethylene glycol (PEG) or polyether siloxane.

7. The composition of any one of paragraphs 1 to 6, wherein the ratio of titanium dioxide to mineral filler is equal to or less than about 3:1 , for example about 3:2.

8. The composition of any one of paragraphs 1 to 7, wherein the mineral filler has a moisture content equal to or less than about 1 wt%.

9. The composition of any one of paragraphs 1 to 8, wherein the mineral filler has a L^* whiteness equal to or greater than about 90, for example equal to or greater than about 94.

10. The composition of any one of paragraphs 1 to 9, wherein the mineral filler has a b^* yellowness ranging from about -1 .5 to about 4, for example from about -1.5 to about 2, for example from about 0.5 to about 1 .5.

1 1 . The composition of any one of paragraphs 1 to 10, wherein the mineral filler has a Y(D65) equal to or greater than about 85 %, for example equal to or greater than about 90 %. The composition of any one of paragraphs 1 to 1 1 , wherein the mineral filler has a dso equal to or less than about 2.5 μηη. The composition of any one of paragraphs 1 to 12, wherein the mineral filler has a dso equal to or less than about 0.2 μηη. The composition of any one of paragraphs 1 to 13, wherein the mineral filler has a dg5 equal to or less than about 8 μηι. The composition of any one of paragraphs 1 to 14, wherein the mineral filler has a dg5 equal to or less than about 1 μηι. The composition of any one of paragraphs 1 to 15, wherein the composition has a L^* whiteness equal to or greater than about 85, for example equal to or greater than about 88, for example equal to or greater than about 90, for example equal to or greater than about 92 when it is in the form of a sheet having a thickness of 0.3 mm or less. The composition of any one of paragraphs 1 to 16, wherein when the composition has a b^* yellowness equal to or less than about 6 when it is in the form of a sheet having a thickness of 0.3 mm or less. The composition of any one of paragraphs 1 to 17, wherein the composition has a Y(D65) equal to or greater than about 70 % or equal to or greater than about 85 % when it is in the form of a sheet having a thickness of 0.3 mm or less. The composition of any one of paragraphs 1 to 18, wherein the composition has a gloss at 60° that is equal to or greater than about 65 %. The composition of any one of paragraphs 1 to 19, wherein the composition has a % light transmission at 600 nm equal to or less than about 25% when it is in the form of a sheet having a thickness of 0.3 mm or less. The composition of any one of paragraphs 1 to 15, wherein the composition further comprises carbon black and/or a black dye and/or a black pigment. The composition of any one of paragraphs 1 to 21 , wherein the composition is a masterbatch. The composition of paragraph 22, wherein the composition comprises equal to or greater than about 50 wt% or equal to or greater than about 60 wt% total titanium dioxide and mineral filler. The composition of any one of paragraphsl to 21 , wherein the composition is in the form of a sheet having a thickness equal to or less than about 0.5 mm. The composition of paragraph 24, wherein the sheet has a thickness equal to or less than about 0.3 mm. The composition of paragraph 24 or 25, wherein the composition comprises equal to or greater than about 5 wt% total titanium dioxide and mineral filler, for example from about 5 wt% to about 20 wt% total titanium dioxide and mineral filler. The composition of any one of paragraphs 24 to 26 having a L^* whiteness equal to or greater than about 85 or equal to or greater than about 88 or equal to or greater than about 90, for example equal to or greater than about 92. The composition of any one of paragraphs 24 to 27 having a b^* yellowness equal to or less than about 6. The composition of any one of paragraphs 24 to 28 having a Y(D65) equal to or greater than about 70 % or equal to or greater than about 85 %. The composition of any one of paragraphs 24 to 29 having a gloss at 60° that is equal to or greater than about 65 %. The composition of any one of paragraphs 24 to 30, wherein the composition has a % light transmission at 600 nm equal to or less than about 25%. The composition of any one of paragraphs 24 to 31 , wherein the sheet is shaped into a container suitable for holding a solid and/or liquid. A bilayer comprising:

a first layer comprising a black dye or pigment; and

a second layer comprising a composition according to any one of paragraphs 24 to 32. 34. The bilayer of paragraph 33, wherein the first layer comprises a polymer.

35. The bilayer of paragraph 33 or 34, wherein the first layer comprises a polyester, for example polyethylene terephthalate or polybutylene terephthalate.

36. The bilayer of any one of paragraphs 33 to 35, wherein the first layer has a L^* whiteness equal to or less than about 20.

37. The bilayer of any one of paragraphs 33 to 36, wherein the black pigment is carbon black.

38. The bilayer of any one of paragraphs 33 to 37, wherein the first layer further comprises titanium dioxide. 39. The bilayer of any one of paragraphs 33 to 38, wherein the first layer further comprises a mineral filler.

40. The bilayer of paragraph 39, wherein the first layer is identical to the second layer except that it further comprises a back pigment or black dye.

41 . The bilayer of any one of paragraphs 33 to 40, wherein the bilayer has a % light transmission at 600 nm equal to or less than about 1 %.

42. The bilayer of any one of paragraphs 33 to 41 , wherein the bilayer has a

thickness of 0.5 mm or less.

43. The bilayer of any one of paragraphs 33 to 42, wherein the bilayer is shaped into a container suitable for holding a solid and/or liquid. 44. The bilayer of paragraph 43, wherein the first layer faces the inside of the

container and the second layer faces the outside of the container.

45. A container formed from a sheet of any one of paragraphs 24 to 32 or formed from a bilayer of any one of paragraphs 33 to 44.

Claims

1 . A composition comprising polyester, titanium dioxide and a mineral filler, wherein the ratio of the titanium dioxide to the mineral filler is equal to or greater than about 1 :1 and equal to or less than about 5:1.

2. The composition of claim 1 , wherein the polyester is polyethylene terephthalate (PET) or polybutylene terephthalate (PBT).

3. The composition of claim 1 or 2, wherein the mineral filler is kaolin and/or talc.

4. The composition of any one of claims 1 to 3, wherein the mineral filler is surface- treated with a hydrophilic polymer such as polyethylene glycol (PEG) or polyether siloxane.

5. The composition of any one of claims 1 to 4, wherein the ratio of titanium dioxide to mineral filler is equal to or less than about 3:1 , for example about 3:2.

6. The composition of any one of claims 1 to 5, wherein the mineral filler has:

(a) a moisture content equal to or less than about 1 wt%; and/or

(b) a L^* whiteness equal to or greater than about 90, for example equal to or greater than about 94; and/or

(c) a b^* yellowness ranging from about -1 .5 to about 4, for example from about - 1 .5 to about 2, for example from about 0.5 to about 1 .5; and/or

(d) a Y(D65) equal to or greater than about 85 %, for example equal to or greater than about 90 %; and/or

(e) a dso equal to or less than about 2.5 μηι; and/or

(f) a dg5 equal to or less than about 8 μηι.

7. The composition of any one of claims 1 to 6, wherein the composition has:

(a) a L^* whiteness equal to or greater than about 85, for example equal to or greater than about 90 when it is in the form of a sheet having a thickness of 0.3 mm or less; and/or

(b) a b^* yellowness equal to or less than about 6 when it is in the form of a sheet having a thickness of 0.3 mm or less; and/or

(c) a Y(D65) equal to or greater than about 85 % when it is in the form of a sheet having a thickness of 0.3 mm or less; and/or (d) a gloss at 60° that is equal to or greater than about 65 %; and/or

(e) a % light transmission at 600 nm equal to or less than about 25% when it is in the form of a sheet having a thickness of 0.3 mm or less.

8. The composition of any one of claims 1 to 7, wherein the composition further comprises carbon black and/or a black dye and/or a black pigment.

9. The composition of any one of claims 1 to 8, wherein the composition is a masterbatch, for example comprising equal to or greater than about 50 wt% total titanium dioxide and mineral filler.

10. The composition of any one of claims 1 to 9, wherein the composition is in the form of a sheet having a thickness equal to or less than about 0.5 mm.

1 1 . The composition of claim 9 or 10, wherein the composition comprises equal to or greater than about 5 wt% total titanium dioxide and mineral filler, for example from about 5 wt% to about 20 wt% total titanium dioxide and mineral filler.

12. A bilayer comprising:

a first layer comprising a black dye or pigment; and

a second layer comprising a composition according to any one of claims 1 to 1 1.

13. The bilayer of claim 12, wherein the first layer comprises a polyester such as polyethylene terephthalate or polybutylene terephthalate.

14. The bilayer of claim 12 or 13, wherein the first layer is identical to the second layer except that it further comprises a black pigment or black dye.

15. A container formed from a sheet of any one of claims 10 or 1 1 or formed from a bilayer of any one of claims 12 to 14.