laminates

Abstract

Laminates comprising one or more polymeric barrier layers comprising sub-micron pores and / or sub-micron particles. A method of insulation comprising disposing the laminates between a source of radiation and a space or object to be insulated is also described, as are cargo covers and apparel utilising the laminates.

Description

[0001] LAMINATES

[0002] TECHNICAL FIELD

[0003] This invention relates to laminates. In particular, though not exclusively, this invention relates to laminates for thermal insulation and to methods of thermal insulation using such laminates.

[0004] BACKGROUND

[0005] Thermal insulation reduces heat transfer by providing a barrier which mitigates against one or more of conduction, convection, and radiation of heat.

[0006] In some insulation applications, radiant heat gain, and in particular solar heat gain, can be an especially significant factor. One such application are cargo covers.

[0007] Many products are transported long distances as cargo and are required to be kept within defined temperature ranges during transport. Pharmaceutical products and perishable food products are examples of such products, as are certain electronic items. Products may be shipped by any known means, road, ship or air transport, and are usually packed on pallets for ease of handling during shipping.

[0008] Palletised goods may be potentially subjected to wide temperature fluctuations during transport. For example, they may be held at relatively low temperatures in the cargo hold of an aircraft and then left outside prior to the next stage of their journey and be subjected to high incident radiation and high ambient temperatures.

[0009] Products which are particularly sensitive to temperature changes during transport may advantageously be palletised and then protected with a thermal insulation cover (cargo cover). A cargo cover may, for example, cover part of a pallet, for example the four sides and top of the pallet or, by providing a protective sheet under the pallet, may cover all six sides of the pallet. It may alternatively cover only the top or sides of a pallet.

[0010] WO2018142133 provides a flexible, vapour permeable cargo cover laminate comprising an outer layer comprising a low-emissivity surface on an outward face of the outer layer; an inner convection barrier layer and an insulation core comprising a fibrous wadding, the insulation core being sandwiched between the outer and inner layers.

[0011] There remains a need to further improve the performance of thermal insulation, particularly in relation to mitigating solar heat gain.

[0012] It is an object of the invention to address this or another problem associated with the prior art at least in part. SUMMARY OF THE INVENTION

[0013] From a first aspect, the invention provides a laminate comprising a plurality of polymeric barrier layers comprising sub-micron pores and / or sub-micron particles.

[0014] It has been found that such a laminate can provide an effective barrier to solar radiation and is useful as thermal insulation. In particular, it has been observed that the presence of sub-micron pores and / or sub-micron particles in the barrier layers can lead to enhanced solar barrier properties in the laminate.

[0015] From a second aspect, the invention provides a laminate comprising a polymeric barrier layer comprising sub-micron pores and / or sub-micron particles and a low emissivity film layer.

[0016] From a third aspect, the invention provides a cargo cover comprising a laminate according to the first or second aspect of the invention.

[0017] From a fourth, aspect the invention provides an item of apparel comprising a laminate according to the first or second aspect of the invention.

[0018] From a fifth aspect, the invention provides the use of a laminate according to the first or second aspect of the invention for the purpose of insulation.

[0019] From a sixth aspect, the invention provides a method of insulation, the method comprising disposing a laminate according to the first or second aspect of the invention between a source of radiation and a space or object to be insulated.

[0020] Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", mean "including but not limited to", and do not exclude other components, integers or steps. Moreover the singular encompasses the plural unless the context otherwise requires: in particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[0021] For simplicity, all references herein to "one or more" layers herein is to be read as also embracing, as an option, each or all of the relevant layers.

[0022] Optional features of each aspect of the invention may be as described in connection with any of the other aspects. Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and / or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and / or features of any embodiment can be combined in any way and / or combination, unless such features are incompatible.

[0023] DETAILED DESCRIPTION

[0024] Aspects of the invention relate to a laminate comprising a plurality of polymeric barrier layers each comprising sub-micron pores and / or sub-micron particles.

[0025] Each of the barrier layers may independently comprise sub-micron pores, sub-micron particles, or both. Suitably, each of the barrier layers may comprise sub-micron pores and sub-micron particles.

[0026] Without wishing to be bound by theory, the presence of sub-micron pores and / or submicron particles in the barrier layers can lead to enhanced solar barrier properties in the laminate.

[0027] Suitably, the laminate may comprise at least two, at least three, or at least four, or at least five, or at least six of the barrier layers. Optionally, the laminate may comprise no more than ten, no more than nine or no more than eight of the barrier layers.

[0028] Optionally, the barrier layers may be identical in structure.

[0029] Advantageously, one or more of the barrier layers may be overlying. An overlying barrier layer is in contact with at least one other overlying barrier layer.

[0030] Suitably, the laminate may be free from intermediate layers and / or additional layers. Thus, the laminate's layers may consist of the barrier layers.

[0031] Advantageously, the barrier layers may be laminated to one another. For example, one or more of the barrier layers may be laminated to one another using thermal bonding, ultrasonic bonding, adhesive bonding, or a combination thereof. Advantageously, the bonding may be intermittent.

[0032] Without wishing to be bound by theory, it is thought that the presence of sub-micron pores and / or particles in one or more of the barrier layers can lead to Mie scattering of solar radiation, and that this can in turn contribute to greater enhancement of solar radiation barrier properties in the laminate. Surprisingly improved performance may be achieved.

[0033] Notably, the ultraviolet (UV) region of solar radiation covers the wavelength of from about 10 to 400 nm and the visible region the wavelength greater than 400 to about 800 nm. UV radiation can be subdivided according to ISO standard ISO 21348. Of particular concern in mitigating solar heat gain is UV radiation in the range of from 200 to 400 nm. The term "sub-micron" as used herein refers to pores or particles that have a diameter of up to and including one micron, suitable in the range of from 0.1 nm to 1 micron. For example, the sub-micron pores or particles may include pores or particles with a diameter in the range of from 100 to 300 nm, pores or particles in the range of 500 to 800 nm, or both. These diameters target UV and visible light respectively.

[0034] The presence of sub-micron pores or particles in the barrier layers may be detected by Scanning Electron Microscope (SEM) images, or by mercury porosimetry (ISO 15901- 1 :2016) for pores or laser diffraction (ISO 13320:2020) for particles.

[0035] Advantageously, one or more of the barrier layers may comprise sub-micron pores. Optionally, one or more of the barrier layers may comprise pores with a pore size distribution including sub-micron pores as determined by mercury porosimetry (ISO 15901- 1 :2016).

[0036] To help enhance Mie scattering, it is desirable to include a sizeable number of pores with a sub-micron diameter.

[0037] Advantageously, the porosity of one or more of the barrier layers, as determined by mercury porosimetry (ISO 15901-1:2016), may be at least 25%, or at least 30%, or at least 35%. Suitably, the porosity may be at most 60%, or at most 50% or at most 40%. For example, the porosity may be in the range of from 25% to 60%, or 30% to 50% or 35% to 40%.

[0038] Suitably, at least 30%, or at least 40% or at least 50% of the pore volume of one or more of the barrier layers may be in pores having a pore diameter in the range of from 0.1 to 1 micron, as determined by mercury porosimetry (ISO 15901-1:2016).

[0039] Advantageously, the total intrusion volume of one or more of the barrier layers, as determined by mercury porosimetry (ISO 15901-1:2016), may be at least 0.4 mL / g, or at least 0.6 mL / g, or at least 0.7mL / g. Suitably, the total intrusion volume may be at most 1.0 mL / g, or at most 0.9 or at most 0.8 mL / g. For example, the total intrusion volume may be in the range of from 0.4 to 1.0 mL / g, or 0.6 mL / g to 0.9 mL / g, or 0.7 mL / g to 0.8 mL / g.

[0040] Advantageously, one or more of the barrier layers may have a pore volume of at least 0.5 mL / g, or at least 0.6 mL / g within pores having a pore diameter in the range of from 0.1 to 1 micron, as determined by mercury porosimetry (ISO 15901-1 :2016).

[0041] Optionally, the D50 (volume distribution) of pores in one or more of the barrier layers may be at most 3 micron, at most 1 micron, at most 0.8 micron, or at most 0.6 micron. Suitably, the D50 (volume distribution) of pores in one or more of the barrier layers may be at least 10 nm, at least 0.1 micron or at least 0.3 micron. For example, the D50 (volume distribution) of pores may be in the range of from 10 nm to 3 micron, or in the range of from 0.1 micron to 0.8 micron, or in the range of from 0.3 to 0.6 micron. All these may be determined by mercury porosimetry (ISO 15901-1:2016).

[0042] Optionally, one or more of the barrier layers may have a total pore area as determined by mercury porosimetry (ISO 15901-1:2016) of at least 15 m2 / g, or at least 20 m2 / g or at least 30 m2 / g. Optionally, the total pore area as determined by mercury porosimetry (ISO 15901-1:2016) may be at most 50 m2 / g, or at most 45 m2 / g, or at most 40 m2 / g. For example, the total pore area as determined by mercury porosimetry (ISO 15901-1 :2016) may be in the range of from 15 to 50 m2 / g or in the range of from 20 to 45 m2 / g or in the range of from 30 to 40 m2 / g.

[0043] Suitably, one or more of the barrier layers may have an average pore diameter (4V / A) as determined by mercury porosimetry (ISO 15901-1:2016) of at most 0.5 micron, or at most 0.2 micron, or at most 0.1 micron. Optionally, the average pore diameter (4V / A) as determined by mercury porosimetry (ISO 15901-1:2016) may be at least 10 nm, suitably at least 4nm or at least 10 nm or at least 50 nm. For example, the average pore diameter (4V / A) as determined by mercury porosimetry (ISO 15901-1:2016) may be in the range of from 4 nm to 0.5 micron, or in the range of from 10 nm to 0.2 micron or in the range of from 50 nm to 0.1 micron.

[0044] It may be of advantage for one or more layers to have a significant pore volume in pores with a diameter up to 10 nm. Suitably, at least 1%, or at least 2% or at least 3% of the pore volume of one or more of the barrier layers may be in pores having a pore diameter of up to 10 nm, as determined by mercury porosimetry (ISO 15901-1:2016). The presence of such very small pores may contribute to thermal resistance, allowing the laminate to better mitigate conduction of heat.

[0045] Advantageously, one or more of the barrier layers may comprise sub-micron particles. Optionally, one or more of the barrier layers may comprise particles with a particle size distribution including sub-micron particles as determined by laser diffraction (ISO 13320:2020).

[0046] To help enhance Mie scattering, it is desirable to include a sizeable number of particles with a sub-micron diameter. Such particles can themselves enhance scattering and / or aid the formation of pores, for example upon stretching of the layer.

[0047] Optionally, one or more of the barrier layers may comprise a particle loading of at least 10% wt, or at least 20% wt or at least 30% wt based on the total weight of the layer. Suitably, the total particle loading may be at most 80 % wt or at most 60% wt or at most 40% wt based on the total weight of the layer. For example, the particle loading may be in the range of from 10 to 80 % wt, or in the range of from 20 to 60 % wt, or in the range of from 30 to 40 % wt based on the total weight of the layer.

[0048] Optionally, the D50 (volume) of particles in one or more of the barrier layers may be at most 3 micron, at most 1.5 micron, at most 1 micron, or at most 0.8 micron. Suitably, the D50 (volume) of particles in one or more of the barrier layers may be at least 0.1 micron, at least 0.3 micron or at least 0.5 micron. For example, the D50 (volume distribution) of particles may be in the range of from 0.1 to 3 micron, or in the range of from 0.3 to 1.5 micron, or in the range of from 0.5 to 0.8 micron. All these may be determined by laser diffraction (ISO 13320:2020), for example upon forming the layer.

[0049] Optionally, in one or more of the barrier layers the particles may comprise or consist of discontinuous polymer particles. For example ethylene-propylene particles can be embedded in a polymeric matrix of polypropylene. Suitably, the sub-micron particles, or the particles of the layer as a whole, may comprise or consist of a polymeric material, suitably a polyolefin material.

[0050] Optionally, in one or more of the barrier layers the particles may comprise or consist of inorganic material. Suitably, the sub-micron particles, or the particles of the layer as a whole, may comprise or consist of an inorganic material.

[0051] Suitably, the inorganic material may comprise or consist of one or more metal oxides, metal carbonates, metal sulphates, metal chlorides or combinations thereof. Optionally, the submicron particles, or the particles of the layer as a whole, may comprise or consist of titanium dioxide, calcium carbonate, or both.

[0052] Optionally, one or more of the barrier layers may comprise titanium dioxide particles, including sub-micron titanium dioxide particles.

[0053] Suitably, a loading of titanium dioxide particles in one or more of the barrier layers may be at least 1% wt, or at least 4% wt or at least 5% wt based on the total weight of the layer. Optionally, the loading of titanium dioxide particles in one or more of the barrier layers may be at most 20% wt, or at most 15% wt or at most 10% wt based on the total weight of the layer. For example, the loading of titanium dioxide particles in one or more of the barrier layers may be in the range of from 1 to 20 % wt, or in the range of from 4 to 15 % wt, or in the range of from 5 to 10 % wt based on the total weight of the layer.

[0054] Suitably, a D50 (volume) of the titanium dioxide particles in one or more of the barrier layers may be at most 3 micron, at most 1.5 micron, at most 1 micron, or at most 0.8 micron. Suitably, a D50 (volume) of titanium dioxide particles in one or more of the barrier layers may be at least 0.1 micron, at least 0.3 micron or at least 0.5 micron. For example, a D50 (volume distribution) of titanium dioxide particles may be in the range of from 0.1 to 3 micron, or in the range of from 0.3 to 1.5 micron, or in the range of from 0.5 to 0.8 micron. All these may be determined by laser diffraction (ISO 13320:2020), for example upon forming the layer.

[0055] Optionally, one or more of the barrier layers may comprise calcium carbonate particles, including sub-micron calcium carbonate particles.

[0056] Suitably, a loading of calcium carbonate particles in one or more of the barrier layers may be at least 5% wt, or at least 10% wt or at least 15% wt based on the total weight of the layer. Optionally, the loading of calcium carbonate particles in one or more of the barrier layers may be at most 60% wt, or at most 50% wt or at most 40% wt based on the total weight of the layer. For example, the loading of calcium carbonate particles in one or more of the barrier layers may be in the range of from 5 to 60 % wt, or in the range of from 10 to 50 % wt, or in the range of from 15 to 40 % wt based on the total weight of the layer.

[0057] Suitably, a D50 (volume) of calcium carbonate particles in one or more of the barrier layers may be at most 3 micron, at most 1.5 micron, at most 1 micron, or at most 0.8 micron.

[0058] Suitably, a D50 (volume) of calcium carbonate particles in one or more of the barrier layers may be at least 0.1 micron, at least 0.3 micron or at least 0.5 micron. For example, a D50 (volume distribution) of calcium carbonate in one or more of the barrier layers may be in the range of from 0.1 to 3 micron, or in the range of from 0.3 to 1.5 micron, or in the range of from 0.5 to 0.8 micron. All these may be determined by laser diffraction (ISO 13320:2020), for example upon forming the layer.

[0059] One or more of the barrier layers may comprise a polymeric matrix defining the sub-mircon pores and / or bearing the sub-micron particles.

[0060] The polymeric matrix may comprise or consist of any suitable polymer. Suitable examples include polyolefins, optionally a polyethylene or polypropylene.

[0061] Advantageously, the polymeric matrix may comprise or consist of polypropylene.

[0062] Crystalline polypropylene (also known as "isotactic polypropylene") can crystallize in three polymorphic forms: the alpha, beta, and gamma forms. In melt-crystallized material the predominant polymorph is typically the alpha or monoclinic form.

[0063] The beta or pseudohexagonal form generally occurs at levels of only a few percent, unless certain heterogeneous nuclei are present or the crystallization has occurred in a temperature gradient or in the presence of shearing forces. The gamma or triclinic form is typically only observed in low-molecular weight or stereoblock fractions that have been crystallized at elevated pressures. The alpha form is also referred to as " alpha-spherulites" or "alpha-crystals." The beta form is also referred to as "beta-spherulites," "beta-crystals," "beta-form spherulites," or "betacrystallinity." Beta-crystals have a melting point that is generally about 10 to about 15°C lower than that of alpha-crystals.

[0064] Suitably, the polypropylene may comprise beta-nucleated polypropylene. Without wishing to be bound by theory, the presence of beta-spherulites may be of advantage in facilitating scattering of solar radiation and / or in the formation of pores that lead to such scattering.

[0065] The beta-spherulite content of a layer can be defined qualitatively by optical microscopy, or quantitatively by x-ray diffraction.

[0066] In the optical microscopy method, a section microtomed from the sheet is examined in a polarizing microscope using crossed polars. Beta-spherulites show up as being much brighter than alpha spherulites, due to the much higher birefringence of the betaspherulites. Advantageously, in one or more layers beta-spherulites may occupy at least 50% of the field of view using this technique.

[0067] In the x-ray diffraction method the diffraction pattern of the layer is measured, and the heights of the three strongest alpha phase diffraction peaks, Hn0, HI30and H040are determined, and compared to the height of the strong beta phase peak, H300. An empirical parameter known as "K" is defined by the equation:

[0068] K = (H3OO) / [(H3OO) + (HHO) + (HO4O) + (HI3O)]

[0069] The value of the K parameter can vary from 0, for a sample with no beta -crystals, to 1.0 for a sample with all beta-crystals.

[0070] For one or more layers the value of the K parameter may advantageously be in the range of from 0.3 to 0.95, suitably in the range of from 0.4 to 0.85.

[0071] A typical way to include beta-spherulites within a resinous polymer is to incorporate one or more suitable beta-spherulite nucleating agents into the resinous polymer before the sheet is formed. Suitable nucleating agents are taught, for example, in US5310584 and US5594070.

[0072] These known beta-nucleators include:

[0073] (a) the gamma-crystalline form of a quinacridone colorant Permanent Red E3B having the structural formula hereinafter also referred to as "Q-dye";

[0074] (b) the bisodium salt of o-phthalic acid;

[0075] (c) the aluminum salt of 6-quinizarin sulfonic acid; and to a lesser degree

[0076] (d) isophthalic acid and terephthalic acid.

[0077] The polypropylene may comprise one or more beta-spherulite nucleating agents, suitably selected from a) to d) above, for example in an amount in the range from 0.1 to 10 ppm. Suitably, one or more layers may comprise the beta-spherulite nucleating agent "Q-dye" in an amount in the range from 0.1 to 10 ppm.

[0078] Beta nucleants, beta spherulites and particles, can induce microvoiding, i.e. pore formation, in the layer when it is deformed during a thermoforming or stretching process. Without wishing to be bound by theory, such pores may be advantageous in scattering radiation, in particular UV radiation in the laminate.

[0079] Suitably, one or more of the barrier layers may be a thermoformed and / or stretched layer, optionally comprising one or more of beta nucleants, beta spherulites, and particles, for example as hereinabove defined.

[0080] Suitably, one or more of the barrier layers may be formed by a process comprising (a) forming a film containing beta-spherulites, particles, or both and (b) stretching the film. Suitably, the stretching may be multi-axial, for example biaxial.

[0081] When biaxial stretching is used to produce a microporous film starting with an extruded sheet containing high levels of beta crystallinity, porosities in excess of 35% can be achieved, and sometimes porosities as high as 70% can be produced. At these high porosities, the pores become open-cell in nature, and tortuous pathways are produced that allow for high transmission rates for gases such as water vapor.

[0082] Suitably, one or more of the barrier layers may comprise a multi-axially stretched layer, for example a biaxially stretched layer. Without wishing to be bound by theory, such stretching may lead to less elongate pores than monoaxial stretching, and such pores may be more effective in scattering radiation.

[0083] Multi-axial stretching also results in greater isotropy, which enhances the ability of the film in the context of acting as a radiation barrier.

[0084] Suitably, one or more of the barrier layers may have a tensile strength (ASTM D882) in a cross-machine direction (CD) that is at least 50% of that in a machine direction (MD), optionally at least 70%, or even at least 80%.

[0085] Optionally, one or more of the barrier layers may have a moisture vapour transmission rate (MVTR) of at least 500 g / m2 / 24h, or at least 1000 g / m2 / 24h or at least 1500 g / m2 / 24h. MVTR is provided throughout this specification based on testing with a Lyssy Model L80- 5000 Water Vapor Permeability Tester at 100% / 15% RH, i.e. 85% RH difference and 23 C.

[0086] One or more of the barrier layers may be monolithic. For example, a porous biaxially stretched polypropylene film containing beta-spherulites, ethylene-propylene particles, and titanium dioxide particles is sold under the brand Aptra® UV8 by rkw™.

[0087] Alternatively, one or more of the barrier layers may be fibrous. Suitable fibrous layers include non-woven layers, optionally flashspun or meltblown. For example, suitable porous flashspun fibrous layers are sold under the brand Tyvek® by DuPont®.

[0088] Optionally, one or more of the barrier layers may have a thickness of up to 1 mm, suitably up to 500 micron or up to 100 micron. Suitably, one or more of the barrier layers may have a thickness of at least 1 micron, or at least 5 micron or at least 10 micron. For example, one or more of the barrier layers may have a thickness in the range of from 1 micron to 1 mm, or in the range of from 5 micron to 500 micron, or in the range of from 10 micron to 100 micron.

[0089] The laminate may comprise one or more low emissivity film or coating layers.

[0090] "Emissivity" is a known expression of the amount of thermal energy radiated by a material, matter or surface. An ideal material or surface emitting the highest theoretical level of radiant energy would have an emissivity, e, of 1 and an ideal material or surface emitting no radiant energy would have an emissivity of 0. In practice all objects have an emissivity between 0 and 1. All emissivity values (e) herein are given at a temperature of 25 C. For the level of accuracy required in this specification, emissivity can be considered substantially the same over different infra-red wavelengths.

[0091] A low emissivity film or coating in the laminate may optionally have an emissivity of at most 0.3, at most 0.2, at most 0.1, or at most 0.05. Suitably, the emissivity may be at least 0.001 or at least 0.005 or at least 0.001. For example, the emissivity may be in the range of from 0.001 to 0.3 or in the range of from 0.005 to 0.2 or in the range of from 0.001 to 0.1.

[0092] A low emissivity coating layer may conveniently be formed on one or more of the barrier layers. Suitable techniques, such as metallisation, for example aluminisation, are known in the art.

[0093] Advantageously, the laminate may comprise one or more low emissivity film layers. Suitably, the one or more low emissivity film layers may be provided on one side of the laminate. This side may advantageously be oriented as an inner side in use.

[0094] Conveniently, a low emissivity film layer may comprise a metallised, optionally aluminised, polymer substrate. One example of a suitable low emissivity film layer is metallised biaxially oriented polypropylene (BOPP) film.

[0095] Optionally, one or more of the low emissivity film layers many have a thickness of up to 300 micron, suitably up to 100 micron or up to 50 micron. Suitably, one or more of the low emissivity film layers may have a thickness of at least 1 micron, or at least 5 micron or at least 10 micron. For example, one or more of the low emissivity film layers may have a thickness in the range of from 1 micron to 300 micron, or in the range of from 5 micron to 100 micron, or in the range of from 10 micron to 50 micron.

[0096] Optionally, one or more of the low emissivity film layers may be moisture vapour impermeable. However, moisture vapour permeable low emissivity film layers may also be used. Such layers are also known in the art, for example from W02009024804.

[0097] One or more of the low emissivity film layers may be monolithic. Alternatively, one or more of the low emissivity film layers may be fibrous, for example an aluminised flashspun.

[0098] It has been found that the incorporation of one or more low emissivity film layers into the laminate improves insulation performance.

[0099] Surprisingly, it has been found that one or more low emissivity film layers can be laminated to a barrier layer whilst retaining an improvement in insulation performance. This is surprising given that lamination would ordinarily be expected to adversely affect emissivity.

[0100] Optionally, one or more low emissivity film layers may be laminated to a barrier layer using thermal bonding, ultrasonic bonding, adhesive bonding, or a combination thereof. Advantageously, the bonding may be intermittent. Suitably, the laminate may comprise at least two, at least three, or at least four, or at least five, or at least six of the low emissivity film layers. Optionally, the laminate may comprise no more than ten, no more than nine or no more than eight of the low emissivity film layers.

[0101] Optionally, the low emissivity film layers may be identical in structure.

[0102] Advantageously, a plurality of the low emissivity film layers may be overlying. An overlying low emissivity film layer is in contact with at least one other overlying low emissivity film layer.

[0103] Suitably, the laminate may be free from intermediate layers and / or additional layers. Thus, the laminate's layers may consist of the barrier layers and the low emissivity film layers.

[0104] Advantageously, a plurality of the low emissivity film layers may be laminated to one another. For example, a plurality of the low emissivity film layers may be laminated to one another using thermal bonding, ultrasonic bonding, adhesive bonding, or a combination thereof. Advantageously, the bonding may be intermittent.

[0105] The surprising retention of insulation performance upon laminating one or more low emissivity film layers to a barrier layer can also be of benefit with one barrier layer.

[0106] Aspects of the invention relate to a laminate comprising a polymeric barrier layer comprising sub-micron pores and / or sub-micron particles and a low emissivity film layer.

[0107] The one or more barrier layers and one or more low emissivity layers may be laminated to one another, optionally using thermal bonding, ultrasonic bonding, adhesive bonding, or a combination thereof. Advantageously, the bonding may be intermittent.

[0108] Optionally, the barrier layer and low emissivity layer may be as described hereinabove. The laminate may comprise a plurality of barrier layers and / or low emissivity layers.

[0109] A laminate of any aspect the invention may suitably have a thickness of up to 100 mm, suitably up to 50 mm micron or up to 10 mm. Suitably, the laminate may have a thickness of at least 100 micron, or at least 1 mm micron or at least 2 mm. For example, the laminate may have a thickness in the range of from 100 micron to 100 mm, or in the range of from 1 mm to 50 mm, or in the range of from 2 mm to 10 mm.

[0110] Optionally, the laminate may have a moisture vapour transmission rate (MVTR) of at least 500 g / m2 / 24h, or at least 1000 g / m2 / 24h or at least 1500 g / m2 / 24h. A laminate of any aspect of the invention may be incorporated into a cargo cover. Indeed, an aspect of the invention embraces a cargo cover comprising a laminate according to any aspect or embodiment of the invention.

[0111] The term "cargo" is used broadly herein to refer to goods that can be carried on a ship, aircraft, or motor vehicle.

[0112] In principle, the cargo cover can be of any suitable shape or configuration. Advantageously, the cargo cover may define a recess for receiving cargo. Optionally, the recess may be cuboid.

[0113] Optionally, the cargo cover may comprise a plurality of laminates joined together.

[0114] Optionally, the cargo cover may be adapted to cover a pallet of cargo. Cargo pallets are known in the art and comprise cargo disposed on a platform for transportation. Typically, the platform is square or rectangular.

[0115] The cargo cover may be cap-shaped, in particular box-shaped, to receive and fit over a pallet of cargo. In particular, the cargo cover may be generally oblong or square in plan, with four sides, a top, and a bottom opening for receiving cargo. One or more of the top and sides of the cargo cover may comprise or consist of a laminate according to any aspect or embodiment of the invention. Advantageously the top and sides of the cargo cover may comprise or consist of a laminate according to any aspect or embodiment of the invention.

[0116] The laminate may be incorporated into an item of apparel. Indeed, an aspect of the invention also embraces an item of apparel comprising a laminate according to any aspect or embodiment of the invention.

[0117] The apparel may, for example, be an item of clothing or footwear. Advantageously, the apparel may be an item of headgear.

[0118] The invention also embraces the use of a laminate, cargo cover or apparel in accordance with any aspect or embodiment of the invention for the purpose of insulation, optionally insulation from incident sunlight.

[0119] The invention also embraces a method of insulation, the method comprising disposing a laminate, cargo cover or apparel in accordance with any aspect or embodiment of the invention between a source of radiation and a space or object to be insulated.

[0120] Thus, the method may comprise exposing a first side of the laminate, cargo cover or apparel to radiation, with the space or objection being on an opposed, second side. Optionally, the exposure may be over a period of at least 10 minutes, at least 30 minutes or at least 1 hour.

[0121] The radiation may comprise visible light, ultraviolet light or a combination thereof. Suitably, the radiation may be sunlight.

[0122] BRIEF DESCRIPTION OF THE DRAWINGS

[0123] One or more non-limiting examples of the invention will now be described, by way of illustration only, with reference to the accompanying drawings, in which:

[0124] Figure 1 is a plot showing the performance of laminates of Example 1;

[0125] Figure 2 is a plot showing the performance of laminates of Example 2; and

[0126] Figures 3A to 3C show the performance of laminates of Example 3.

[0127] EXAMPLES

[0128] Studies were conducted to compare the insulation properties of different types of laminates under conditions of direct solar exposure.

[0129] All laminates in the following examples were formed by thermally laminating the requisite films together in using a calendar with 19% bonding area. Where only a single film was used, this was also run through the same calendar.

[0130] Example 1 - highly loaded monoaxiallv stretched film laminates

[0131] A barrier film obtained from Thrace Group ®. This was produced by monoaxial stretching of highly loaded polypropylene containing in about 55% wt of calcium carbonate. The mean particle size D50 (volume) was about 1.5 micron.

[0132] The tensile strength of the film in the cross-machine direction (CD) was about 20% of that in the machine direction (MD).

[0133] The pore distribution of the film was determined by mercury porosimetry (ISO 15901- 1 :2016) using MicroActive AutoPore V 9600 2.03.00 with the following results:

[0134] Table 1:

[0135] About 67% of the pore volume was in pores having a pore diameter in the range of from 0.1 to 1 micron, which corresponded to 0.34 ml / g. About 0.6% of the pore volume was in pores up to a diameter of 10 nm. The insulation performance under incident sunlight of a single barrier film was compared to seven laminates containing from two to eight layers of the film.

[0136] A4 samples of the laminates were cut out to act as covers. A temperature logger was placed on a fluted cardboard surface and sealed under each A4 sample which was sealed with tape at the edges to prevent heat entering or escaping. Each sample was exposed to sunlight, with an ambient temperature logger measuring ambient temperature in the shade.

[0137] The difference between the temperature under the sample and the ambient temperature was recorded in °C for a period of 10 hours and expressed as an average % reduction from ambient.

[0138] The results were as follows: Table 2

[0139] A plot of the results in shown in Figure 1.

[0140] While there is an increase in performance between the use of 1 and 3 layers, there doesn't appear to be a consistent pattern in the performance of the material when using increasing layers of this film.

[0141] Example 2 - beta-crystalline biaxially stretched polypropylene film laminates

[0142] Barrier film obtained from rkw™ under the brand Aptra® UV8 was made by biaxial stretching of a polypropylene containing beta-spherulites, ethylene-propylene particles, calcium carbonate particles (about 25% loading with a median particle diameter by volume of about 0.7 micron) and titanium dioxide particles (about 7% loading with a median particle diameter by volume of about 0.7 micron).

[0143] The biaxial stretching led to the formation of pores. Possible mechanisms include the following:

[0144] • Self-cavitation of the beta crystal phase as it transforms into the alpha crystal phase during the stretching process.

[0145] • Cavitation initiated by the calcium carbonate particles embedded in the polypropylene matrix as the polymer de-bonds from these particles during stretching.

[0146] • Craze formation that initiates at the surface of the ethylene-propylene particles embedded in the polypropylene matrix. The tensile strength of the film in the cross-machine direction (CD) was about 90% of that in the machine direction (MD).

[0147] The pore distribution of the film was determined by mercury porosimetry (ISO 15901- 1 :2016) using MicroActive AutoPore V 9600 2.03.00 with the following results: Table 3

[0148] About 62% of the pore volume was in pores having a pore diameter in the range of from 0.1 to 1 micron, which corresponded to 0.47 ml / g. About 3.8% of the pore volume was in pores up to a diameter of 10 nm. The insulation performance under incident sunlight of a single film was compared to seven laminates containing from two to eight layers of the film. A4 samples of the laminates were cut out. A temperature logger was placed on a fluted cardboard surface and sealed under each A4 sample which was sealed with tape at the edges to prevent heat entering or escaping. Each sample was exposed to sunlight, with an ambient temperature logger measuring ambient temperature in the shade.

[0149] The difference between the temperature under the sample and the ambient temperature was recorded in °C for a period of 10 hours and expressed as an average % reduction from ambient.

[0150] The results were as follows:

[0151] Table 4

[0152] A plot of the results in shown in Figure 2.

[0153] From the data shown here it appears that the performance of the cover improves by a large amount when increasing from 1 layer to 2 layers and then gradually increases from 2 layers to 5 layers where it then appears to remain at a similar performance up to 8 layers.

[0154] Overall, the barrier layer utilised in this example offered better performance than the barrier layer used in Example 1. Performance when laminating a plurality of layers was surprisingly improved, more consistently so than in Example 1.

[0155] The barrier film used in this example offers surprising advantages in the specific context of lamination, despite having a lower loading of calcium carbonate (and particles overall) than the barrier layer of Example 1. Example 3 - addition of low emissivity film

[0156] A study was conducted to further improve the performance of the 5xfilm laminate of Example 2 by incorporation of one or more low emissivity film layers.

[0157] In this study 18 cardboard boxes measuring 400mm x 400mm x 400mm were built on a pallet to represent a cargo load. For each laminate to be tested, an experimental cargo cover, generally cuboid with four sides and a top dimensioned to fit snugly over the carboard boxes was formed by taping together five pieces of the tested laminate. The cargo cover was placed over the cardboard boxes. A data logger was positioned on top of the boxes, under the top of the cover, to measure changes in temperature. The covered structure was exposed to sunlight for about 10 hours. For comparative runs, two such structures were used in parallel with different covers.

[0158] Example 3A

[0159] In a first comparative run a single low emissivity film layer of an aluminised biaxially oriented polypropylene (BOPP) film with a thickness of about 15 micron and an emissivity of about 0.05 was included as the bottom layer of a laminate (facing the inside of the cargo cover) additionally comprising five barrier films as described in Example 2. The 5xfilm from Example 2 was used as a reference. A plot of the temperature from the data loggers is shown in Figure 3A. The results showed a 29.83% reduction from ambient for the laminate including the low emissivity film compared to a 18.18% reduction for the comparable laminate without the low emissivity film.

[0160] This run showed that very high levels of insulation can be achieved by adding a low emissivity layer. Surprisingly, this was achieved by laminating the low emissivity film to the barrier layers, which would ordinarily be expected to destroy the functionality of the low emissivity film.

[0161] Example 3B

[0162] In a second comparative run two low emissivity film layers of the same aluminised biaxially oriented polypropylene (BOPP) film were included as overlying bottom layers (facing the inside of the cargo cover) of a first laminate additionally comprising five barrier films as described in Example 2. In a second laminate the same two low emissivity layers were split, with one of the low emissivity layers being the bottom layer (facing the inside of the cargo cover) and the other being interleaved between the third and fourth ones of five barrier films as described in Example 2. A plot of the temperature from the data loggers is shown in Figure 3B. The results showed a 23.42% reduction from ambient for the laminate including the two low emissivity films as overlying bottom layers compared to a 20.11% reduction for the comparable laminate with the low emissivity films split. This run showed that, surprisingly, overlying low emissivity layers performed better than an arrangement where the same low emissivity layers were split in different parts of the laminate.

[0163] Example 3C In a third comparative run the laminate with a single low emissivity film layer from Example 3A was compared with a corresponding laminate where the low emissivity film was an ultralow emissivity film with an emissivity of about 0.001. A plot of the temperature from the data loggers is shown in Figure 3C. The results showed a 22.41% reduction from ambient for the laminate from Example 3A the two low emissivity films as overlying bottom layers compared to a 19.33% reduction for the comparable laminate with the ultra low emissivity film.

[0164] This run showed that, surprisingly, an ultra-low emissivity film did not outperform the aluminised biaxially oriented polypropylene (BOPP) film.

[0165] CLAUSES Aspects and embodiments of the invention are set out in the following clauses:

[0166] 1. A laminate comprising a plurality of polymeric barrier layers each comprising submicron pores and / or sub-micron particles.

[0167] 2. The laminate of clause 1, wherein the laminate comprises at least three, or at least four, or at least five, or at least six of the barrier layers.

[0168] 3. The laminate of any preceding clause, wherein the barrier layers are identical in structure.

[0169] 4. The laminate of any preceding clause, wherein the barrier layers are overlying.

[0170] 5. The laminate of any preceding clause, wherein the barrier layers are laminated to one another, optionally using thermal bonding, ultrasonic bonding, adhesive bonding, or a combination thereof.

[0171] 6. The laminate of any preceding clause, wherein the sub-micron pores and / or sub-micron particles have a diameter in the range of from 0.1 to 1 micron.

[0172] 7. The laminate of any preceding clause, wherein the sub-micron pores and / or sub-micron particles include pores and / or particles with a diameter in the range of from 100 to 300 nm, or in the range of 500 to 800 nm, or both.

[0173] 8. The laminate of any preceding clause, wherein one or more of the barrier layers comprises sub-micron pores, optionally wherein one or more of the barrier layers comprises pores with a pore size distribution including sub-micron pores as determined by mercury porosimetry (ISO 15901-1 :2016).

[0174] 9. The laminate of any preceding clause, wherein the porosity of one or more of the barrier layers, as determined by mercury porosimetry (ISO 15901-1 :2016), is at least 25%, or at least 30%, or at least 35%.

[0175] 10. The laminate of any preceding clause, wherein at least 30%, or at least 40% or at least 50% of the pore volume of one or more of the barrier layers is in pores having a pore diameter in the range of from 0.1 to 1 micron, as determined by mercury porosimetry (ISO 15901-1:2016).

[0176] 11. The laminate of any preceding clause, wherein the total intrusion volume of one or more of the barrier layers, as determined by mercury porosimetry (ISO 15901-1 :2016) is at least 0.4 mL / g, or at least 0.6 mL / g, or at least 0.7mL / g.

[0177] 12. The laminate of any preceding clause, wherein one or more of the barrier layers has a pore volume of at least 0.5 mL / g, or at least 0.6 mL / g within pores having a pore diameter in the range of from 0.1 to 1 micron, as determined by mercury porosimetry (ISO 15901- 1 :2016).

[0178] 13. The laminate of any preceding clause, wherein the D50 (volume distribution) of pores in one or more of the barrier layers is at most 3 micron, at most 1 micron, at most 0.8 micron, or at most 0.6 micron, as determined by mercury porosimetry (ISO 15901-1 :2016).

[0179] 14. The laminate of any preceding clause, wherein the D50 (volume distribution) of pores in one or more of the barrier layers is at least 10 nm, at least 0.1 micron or at least 0.3 micron, as determined by mercury porosimetry (ISO 15901-1:2016).

[0180] 15. The laminate of any preceding clause, wherein the D50 (volume distribution) of pores in one or more of the barrier layers is in the range of from 10 nm to 3 micron, or in the range of from 0.1 nm to 0.8 micron, or in the range of from 0.3 to 0.6 micron, as determined by mercury porosimetry (ISO 15901-1:2016).

[0181] 16. The laminate of any preceding clause, wherein one or more of the barrier layers has a total pore area as determined by mercury porosimetry (ISO 15901-1 :2016) of at least 15 m2 / g, or at least 20 m2 / g or at least 30 m2 / g.

[0182] 17. The laminate of any preceding clause, wherein one or more of the barrier layers has an average pore diameter (4V / A) as determined by mercury porosimetry (ISO 15901-1:2016) of at most 0.5 micron, or at most 0.2 micron, or at most 0.1 micron. 18. The laminate of any preceding clause, wherein at least 1%, or at least 2% or at least 3% of the pore volume of one or more layers is in pores having a pore diameter of up to 10 nm, as determined by mercury porosimetry (ISO 15901-1:2016)

[0183] 19. The laminate of any preceding clause, wherein one or more of the barrier layers comprises sub-micron particles, optionally wherein one or more of the barrier layers comprises particles with a particle size distribution including sub-micron particles as determined by laser diffraction (ISO 13320:2020).

[0184] 20. The laminate of any preceding clause, wherein one or more of the barrier layers comprises a particle loading in the range of from 10 to 80 % wt, or in the range of from 20 to 60 % wt, or in the range of from 30 to 40 % wt based on the total weight of the layer.

[0185] 21. The laminate of any preceding clause, wherein the D50 (volume) of particles in one or more of the barrier layers may is at most 3 micron, at most 1.5 micron, at most 1 micron, or at most 0.8 micron, as determined by laser diffraction (ISO 13320:2020).

[0186] 22. The laminate of any preceding clause, wherein the D50 (volume) of particles in one or more of the barrier layers is at least 0.1 micron, at least 0.3 micron or at least 0.5 micron, as determined by laser diffraction (ISO 13320:2020).

[0187] 23. The laminate of any preceding clause, wherein in one or more of the barrier layers the sub-micron particles comprise a polymeric material.

[0188] 24. The laminate of any preceding clause, wherein in one or more of the barrier layers the sub-micron particles comprise an inorganic material.

[0189] 25. The laminate of clause 24 wherein the inorganic material comprises or consists of one or more metal oxides, metal carbonates, metal sulphates, metal chlorides or combinations thereof.

[0190] 26. The laminate of any preceding clause, wherein the sub-micron particles, or the particles of the layer as a whole, comprise or consist of titanium dioxide, calcium carbonate, or both.

[0191] 27. The laminate of any preceding clause, wherein a loading of titanium dioxide particles in the layer is in the range of from 1 to 20 % wt, or in the range of from 4 to 15 % wt, or in the range of from 5 to 10 % wt based on the total weight of the layer.

[0192] 28. The laminate of any preceding clause, wherein a D50 (volume distribution) of titanium dioxide particles in one or more of the barrier layers is in the range of from 0.1 to 3 micron, or in the range of from 0.3 to 1.5 micron, or in the range of from 0.5 to 0.8 micron. 29. The laminate of any preceding clause, wherein a loading of calcium carbonate particles in one or more of the barrier layers is in the range of from 5 to 60 % wt, or in the range of from 10 to 50 % wt, or in the range of from 15 to 40 % wt based on the total weight of the layer.

[0193] 30. The laminate of any preceding clause, wherein a D50 (volume distribution) of calcium carbonate in one or more of the barrier layers is in the range of from 0.1 to 3 micron, or in the range of from 0.3 to 1.5 micron, or in the range of from 0.5 to 0.8 micron.

[0194] 31. The laminate of any preceding clause, wherein one or more of the barrier layers comprise a polymeric matrix defining the sub-mircon pores and / or bearing the sub-micron particles.

[0195] 32. The laminate of clause 31, wherein the polymeric matrix comprises or consists of a polyolefin, optionally a polyethylene or polypropylene.

[0196] 33. The laminate of clause 31 or clause 32, wherein the polymeric matrix comprises or consists of polypropylene.

[0197] 34. The laminate of clause 33, wherein the polypropylene comprises beta-nucleated polypropylene.

[0198] 35. The laminate of clause 34, wherein the polypropylene has a "K" parameter in the range of from 0.3 to 0.95, determined from a diffraction pattern of the layer by measuring the heights of the three strongest alpha phase diffraction peaks, Hn0, HI30and H040and the height of the strong beta phase peak, H3Oo, K being (H3oo) / [(H3oo)+(Hno)+(Ho4o)+(Hi3o)].

[0199] 36. The laminate of any one of clauses 33 to 35 wherein the polypropylene comprises one or more beta-spherulite nucleating agents, optionally in an amount in the range from 0.1 to 10 ppm.

[0200] 37. The laminate of any preceding clause, wherein one or more of the barrier layers is a thermoformed and / or stretched layer, optionally comprising one or more of beta nucleants, beta spherulites, and particles.

[0201] 38. The laminate of any preceding clause, wherein one or more of the barrier layers is formed by a process comprising (a) forming a film containing beta-spherulites, particles or both and (b) stretching the film.

[0202] 39. The laminate of any preceding clause, wherein one or more of the barrier layers comprises a multi-axially stretched layer, for example a biaxially stretched layer. 40. The laminate of any preceding clause, wherein one or more of the barrier layers has a tensile strength (ASTM D882) in a cross-machine direction (CD) that is at least 50% of that in a machine direction (MD), optionally at least 70%, or even at least 80%.

[0203] 41. The laminate of any preceding clause, wherein one or more of the barrier layers has a moisture vapour transmission rate (MVTR) of at least 500 g / m2 / 24h, or at least 1000 g / m2 / 24h or at least 1500 g / m2 / 24h.

[0204] 42. The laminate of any preceding clause, wherein one or more of the barrier layers are monolithic or fibrous.

[0205] 43. The laminate of any preceding clause, wherein the one or more of the barrier layers comprise a nonwoven, optionally flashspun or meltblown.

[0206] 44. The laminate of any preceding clause, wherein one or more of the barrier layers have a thickness in the range of from 1 micron to 1 mm, or in the range of from 5 micron to 500 micron, or in the range of from 10 micron to 100 micron.

[0207] 45. The laminate of any preceding clause comprising one or more low emissivity film or coating layers, optionally with an emissivity of at most 0.3, at most 0.2, at most 0.1, or at most 0.05.

[0208] 46. The laminate of any preceding clause comprising one or more low emissivity film layers, optionally on one side of the laminate.

[0209] 47. The laminate of clause 46 wherein the one or more low emissivity film layers are laminated to one of the barrier layers, optionally using thermal bonding, ultrasonic bonding, adhesive bonding, or a combination thereof.

[0210] 48. The laminate of clause 46 or clause 47 comprising at least three, or at least four, or at least five, or at least six of the low emissivity film layers.

[0211] 49. The laminate of any one of clauses 46 to 48 wherein one or more of the low emissivity film layers is moisture vapour impermeable.

[0212] 50. The laminate of any one of clauses 46 to 49, wherein a plurality of low emissivity film layers are overlying.

[0213] 51. The laminate of any one of clauses 46 to 50 wherein a plurality of the low emissivity film layers are laminated to one another, optionally using thermal bonding, ultrasonic bonding, adhesive bonding, or a combination thereof. 52. A laminate comprising one or more polymeric barrier layers comprising sub-micron pores and / or sub-micron particles and one or more low emissivity film layers.

[0214] 53. The laminate of clause 52 wherein the one or more barrier layers and the one or more low emissivity layer are laminated to one another, optionally using thermal bonding, ultrasonic bonding, adhesive bonding, or a combination thereof.

[0215] 54. The laminate of clause 52 or clause 53, wherein the one or more barrier layers are independently as defined in any of clauses 2 to 44.

[0216] 55. The laminate of any one of clauses 52 to 54, wherein the one or more low emissivity layers are independently as defined in any of clauses 45 to 51

[0217] 56. The laminate of any preceding clause having a thickness in the range of from 100 micron to 100 mm, or in the range of from 1 mm to 50 mm, or in the range of from 2 mm to 10 mm.

[0218] 57. The laminate of any preceding clause having a moisture vapour transmission rate (MVTR) of at least 500 g / m2 / 24h, or at least 1000 g / m2 / 24h or at least 1500 g / m2 / 24h.

[0219] 58. A cargo cover comprising a laminate according to any preceding clause.

[0220] 59. The cargo cover of clause 58 defining a recess for receiving cargo, optionally cuboid.

[0221] 60. The cargo cover of clause 58 or clause 59 wherein the cargo cover comprises a plurality of the laminates according to any one of clauses 1 to 56 joined together.

[0222] 61. The cargo cover of any one of clauses 58 to 60 being box-shaped to fit over a pallet of cargo.

[0223] 62. The cargo cover of any one of clauses 58 to 61 being oblong or square in plan, with four sides, a top, and a bottom opening for receiving cargo.

[0224] 63. The cargo cover of clause 62, wherein one or more of the top and sides of the cargo cover comprise or consist of a laminate according to any one of clauses 1 to 57.

[0225] 64. An item of apparel comprising a laminate according to any one of clauses 1 to 57.

[0226] 65. The item of apparel of clause 64, wherein the item is an item of clothing or footwear, optionally an item of headgear.

[0227] 66. Use of a laminate, cargo cover or item of apparel according to any preceding clause for the purpose of insulation, optionally insulation from incident sunlight. 67. A method of insulation, the method comprising disposing a laminate, cargo cover or item of apparel according to any preceding clause between a source of radiation and a space or object to be insulated.

[0228] 68. The method of clause 67 comprising exposing a first side of the laminate, cargo cover or apparel to radiation, with the space or objection being on an opposed, second side.

[0229] 69. The method of clause 68, wherein the exposure is over a period of at least 10 minutes, at least 30 minutes or at least 1 hour.

[0230] 70. The method of any one of clauses 67 to 69 wherein the radiation is sunlight.

Claims

CLAIMS1. A laminate comprising a plurality of polymeric barrier layers each comprising submicron pores and / or sub-micron particles.

2. The laminate of claim 1, wherein the laminate comprises at least three, or at least four, or at least five, or at least six of the barrier layers.

3. The laminate of any preceding claim, wherein the barrier layers are identical in structure.

4. The laminate of any preceding claim, wherein the barrier layers are overlying.

5. The laminate of any preceding claim, wherein the porosity of one or more of the barrier layers, as determined by mercury porosimetry (ISO 15901-1 :2016), is at least 25%, or at least 30%, or at least 35%.

6. The laminate of any preceding claim, wherein at least 30%, or at least 40% or at least 50% of the pore volume of one or more of the barrier layers is in pores having a pore diameter in the range of from 0.1 to 1 micron, as determined by mercury porosimetry (ISO 15901-1:2016).

7. The laminate of any preceding claim, wherein the D50 (volume distribution) of pores in one or more of the barrier layers is in the range of from 0.1 nm to 0.8 micron, or in the range of from 0.3 to 0.6 micron, as determined by mercury porosimetry (ISO 15901- 1 :2016).

8. The laminate of any preceding claim, wherein at least 1%, or at least 2% or at least 3% of the pore volume of one or more layers is in pores having a pore diameter of up to 10 nm, as determined by mercury porosimetry (ISO 15901-1:2016)9. The laminate of any preceding claim, wherein one or more of the barrier layers comprises a particle loading in the range of from 10 to 80 % wt, or in the range of from 20 to 60 % wt, or in the range of from 30 to 40 % wt based on the total weight of the layer.

10. The laminate of any preceding claim, wherein a loading of titanium dioxide particles in the layer is in the range of from 1 to 20 % wt, or in the range of from 4 to 15 % wt, or in the range of from 5 to 10 % wt based on the total weight of the layer.

11. The laminate of any preceding claim, wherein a D50 (volume distribution) of titanium dioxide particles in one or more of the barrier layers is in the range of from 0.1 to 3 micron, or in the range of from 0.3 to 1.5 micron, or in the range of from 0.5 to 0.8 micron.

12. The laminate of any preceding claim, wherein a loading of calcium carbonate particles in one or more of the barrier layers is in the range of from 5 to 60 % wt, or in the range of from 10 to 50 % wt, or in the range of from 15 to 40 % wt based on the total weight of the layer.

13. The laminate of any preceding claim, wherein a D50 (volume distribution) of calcium carbonate in one or more of the barrier layers is in the range of from 0.1 to 3 micron, or in the range of from 0.3 to 1.5 micron, or in the range of from 0.5 to 0.8 micron.

14. The laminate of any preceding claim, wherein one or more of the barrier layers comprise a polymeric matrix defining the sub-mircon pores and / or bearing the sub-micron particles, wherein the polymeric matrix comprises or consists of polypropylene.

15. The laminate of claim 14, wherein the polypropylene comprises beta-nucleated polypropylene.

16. The laminate of claim 15, wherein the polypropylene has a "K" parameter in the range of from 0.3 to 0.95, determined from a diffraction pattern of the layer by measuring the heights of the three strongest alpha phase diffraction peaks, Hn0, HI30and H040and the height of the strong beta phase peak, H300, K being (H3oo) / [(H3oo)+(Hno)+(Ho4o)+(Hi3o)].

17. The laminate of any preceding claim, wherein one or more of the barrier layers is a thermoformed and / or stretched layer, optionally comprising one or more of beta nucleants, beta spherulites, and particles.

18. The laminate of any preceding claim, wherein one or more of the barrier layers has a tensile strength (ASTM D882) in a cross-machine direction (CD) that is at least 50% of that in a machine direction (MD), optionally at least 70%, or even at least 80%.

19. The laminate of any preceding claim comprising one or more low emissivity film or coating layers, optionally with an emissivity of at most 0.3, at most 0.2, at most 0.1, or at most 0.05.

20. The laminate of claim 19 wherein one or more of the low emissivity film layers is moisture vapour impermeable.

21. A cargo cover comprising a laminate according to any preceding claim.

22. The cargo cover of claim 21 defining a recess for receiving cargo, the recess optionally being cuboid.

23. The cargo cover of claims 21 or claim 22 being oblong or square in plan, with four sides, a top, and a bottom opening for receiving cargo.

24. Use of a laminate or cargo cover according to any preceding claim for the purpose of insulation, optionally insulation from incident sunlight.

25. A method of insulation, the method comprising disposing a laminate or cargo cover according to any preceding claim between a source of radiation and a space or object to be insulated, optionally wherein the radiation is sunlight.

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