Multilayer structure suitable for flooring

Abstract

Disclosed is a multilayer structure comprising: (1) a printed porous substrate layer having first and second faces; (2) a polyvinyl chloride clear wear layer disposed on the first face of the printed porous substrate layer; and (3) a polyvinyl chloride backing layer disposed on the second layer of the printed porous substrate layer; and wherein said printed porous substrate layer comprises (i) a polyolefin, a polyester, or a mixture thereof; and (ii) an ink comprising a pigment dispersion; and wherein said pigment dispersion comprises a pigment and a poly(vinyl chloride-vinyl acetate) copolymer binder. Methods for producing the multilayer structures and flooring comprising the multilayer structures are also disclosed.

Description

MULTILAYER STRUCTURE SUITABLE FOR FLOORING

[0001] The present invention relates to multilayer structures suitable for flooring, methods of manufacturing multilayer structures, and articles of flooring comprising multilayer structures.

[0002] Inkjet printing is used in a variety of printing applications, and can provide high resolution images on a range of substrates.

[0003] In recent years, inkjet printing has been used in the production of flooring assemblies. US 11014394 describes a current system for producing vinyl tiles using plastisol. WO 2017 / 017472 describes a current system for producing vinyl tiles using plastisol. Such tiles require an ink to be printed onto plastisol and subsequent cured at high temperatures. A carrier substrate is used during printing and curing, which adds weight to the tiles and can only be used a finite number of times before it must be replaced. The printed plastisol sheets are subsequently fused to a clear PVC layer and a backing PVC layer at a temperature of 150 to 190°C.

[0004] US 11014394WO 2017 / 017472

[0005] It remains a particular problem to produce a multilayer structure suitable for flooring which can be prepared without adding unnecessary weight to the structure, that does not require the use of a carrier substrate, and requires the use of less energy in its production, whilst maintaining image quality throughout heating and curing stages and meeting target bond strength between the printed layer and the PVC layers.

[0006] There is therefore a need for new multilayer structures which solve the above problems.

[0007] The present invention provides a multilayer structure comprising: 　　(1)　　a printed porous substrate layer having first and second faces; 　　(2)　　a polyvinyl chloride clear wear layer disposed on the first face of the printed porous substrate layer; and 　　(3)　　a polyvinyl chloride backing layer disposed on the second layer of the printed porous substrate layer; and 　　wherein said printed porous substrate layer comprises (i) a polyolefin, a polyester, or a mixture thereof; and (ii) an ink comprising a pigment dispersion; 　　and wherein said pigment dispersion comprises a pigment and a poly(vinyl chloride-vinyl acetate) copolymer binder.

[0008] The present invention also provides a method for producing a multilayer structure of the present invention, comprising: 　　-　　providing a printed porous substrate layer a having first and second faces, providing a polyvinyl chloride clear wear layer on the first face of the printed porous substrate layer, and providing a polyvinyl chloride backing layer on the second layer of the printed porous substrate layer to form an intermediate multilayer structure; wherein the printed porous substrate layer, polyvinyl chloride clear wear layer, and polyvinyl chloride backing layer are as described herein with reference to the multilayer structure of the present invention; and 　　-　　heating the intermediate multilayer structure to a temperature in the range of 130°C to 150°C; 　　to form a multilayer structure of the present invention.

[0009] The present invention also provides an article of flooring comprising a multilayer structure of the present invention.

[0010] The multilayer structure, methods, and flooring of the present invention have advantages including: 　　-　　overall weight of the multilayer structure is reduced compared to prior art plastisol-based systems; 　　-　　no curing of the printed layer is required, and the option to omit the curing step is an advantage compared to prior art plastisol-based systems; 　　-　　no carrier substrate is required, and the option to omit the carrier substrate is an advantage compared to prior art plastisol-based systems; 　　-　　good adhesion between layers of the present multilayer system; 　　-　　lamination can be carried out for the present multilayer system at lower temperatures than prior art plastisol-based systems; 　　-　　image quality is maintained when the present multilayer system is laminated; 　　-　　bond strength is improved in the present multilayer system as compared to prior art plastisol-based systems, even at high ink levels.

[0011] Figure 1 is a schematic diagram illustrating differences between the multilayer structure of the present invention and prior art plastisol-based systems.

[0012] The present invention provides a multilayer structure comprising: 　　(1)　　a printed porous substrate layer having first and second faces; 　　(2)　　a polyvinyl chloride clear wear layer disposed on the first face of the printed porous substrate layer; and 　　(3)　　a polyvinyl chloride backing layer disposed on the second layer of the printed porous substrate layer; and 　　wherein said printed porous substrate layer comprises (i) a polyolefin, a polyester, or a mixture thereof; and (ii) an ink comprising a pigment dispersion; 　　and wherein said pigment dispersion comprises a pigment and a poly(vinyl chloride-vinyl acetate) copolymer binder. The printed porous substrate layer

[0013] The printed porous substrate layer typically has a weight of 90 gsm to 250 gsm. Preferably, the printed porous substrate layer has a weight of 110 gsm to 230 gsm. More preferably, the printed porous substrate layer has a weight of 130 gsm to 210 gsm. Still more preferably the printed porous substrate layer has a weight of 150 gsm to 190 gsm. Most preferably the printed porous substrate layer has a weight of 160 gsm to 180 gsm or about 170 gsm. Weight of the printed porous substrate layer can be determined according to ASTM D-3776.

[0014] The printed porous substrate layer typically has a thickness of 145 to 365 μm. Preferably, the printed porous substrate layer has a thickness of 175 to 335 μm. More preferably, the printed porous substrate layer has a thickness of 205 to 305 μm. Still more preferably, the printed porous substrate layer has a thickness of 225 to 325 μm. Most preferably, the printed porous substrate layer has a thickness of 245 to 265 μm, or 250 to 260. Thickness of the printed porous substrate layer can be determined according to ASTM D-374)

[0015] The printed porous substrate layer typically has good temperature resistance. Typically, the printed porous substrate layer has a melting point of 135°C or more (e.g. 135°C to 200°C or 135°C to 180°C). Preferably, the printed porous substrate layer has a melting point of 145°C or more (e.g. 145°C to 200°C or 140°C to 180°C). More preferably, the printed porous substrate layer has a melting point of 150°C or more (e.g. 150°C to 200°C or 150°C to 180°C). Still more preferably, the printed porous substrate layer has a melting point of 155°C or more (e.g. 155°C to 200°C or 155°C to 180°C) Most preferably, the printed porous substrate layer has a melting point of 160°C or more (e.g. 160°C to 200°C or 160°C to 180°C). Melting point can be determined by differential scanning calorimetry (e.g. at a rate of 10°C / min).

[0016] Typically, the printed porous substrate layer has a high temperature shrinkage of 10% or less (e.g. 1% to 10% or 2% to 10%). Preferably, the printed porous substrate layer has a high temperature shrinkage of 8% or less (e.g. 1% to 8% or 2% to 8%) More preferably, the printed porous substrate layer has a high temperature shrinkage of 6% or less (e.g. 1% to 6% or 2% to 6%) Still more preferably, the printed porous substrate layer has a high temperature shrinkage of 5% or less (e.g. 1% to 5% or 2% to 5%) Most preferably, the printed porous substrate layer has a high temperature shrinkage of 4% or less (e.g. 1% to 4% or 2% to 4%). High temperature shrinkage may be measured as shrinkage after heating for 15 minutes in a forced air oven at 135°C.

[0017] Typically, the printed porous substrate layer has a porosity of 45% to 85%. Preferably, the printed porous substrate layer has a porosity of 50% to 80%. More preferably, the printed porous substrate layer has a porosity of 55% to 75%. Still more preferably, the printed porous substrate layer has a porosity of 60% to 70%. Most preferably, the printed porous substrate layer has a porosity of 63% to 67% or about 65%.

[0018] As used herein, porosity is the volume of pore space in the printed porous substrate layer expressed as a percentage of the total volume of the printed porous substrate layer, and can be determined according to ISO 15901-2:2022.

[0019] The printed porous substrate layer comprises a polyolefin, a polyester, or a mixture thereof. Suitable polyolefins include polyethylene, polypropylene, polybutylene, and mixtures thereof. Suitable polyesters include polyethylene terephthalate (PET). The 　　polyolefin and / or polyester typically has a molecular weight (Mw) of around 20,000 to 2,000,000 gmol-1.

[0020] The printed porous substrate layer may further comprise a filler, such as an inorganic filler or non-abrasive inorganic filler. The filler is preferably silica. The filler may be present in the printed porous substrate layer in an amount of up to 80% by weight based on the total weight of the printed porous substrate layer, e.g. 1 to 80% by weight based on the total weight of the printed porous substrate layer. Typically, the filler is present in an amount of 40% to 80% by weight, based on the total weight of the printed porous substrate layer. Preferably, the filler is present in an amount of 45% to 75% by weight, based on the total weight of the printed porous substrate layer. More preferably, the filler is present in an amount of 50% to 70% by weight, based on the total weight of the printed porous substrate layer. Still more preferably, the printed porous substrate layer has the filler is present in an amount of 55% to 65% by weight, based on the total weight of the printed porous substrate layer. Most preferably, the filler is present in an amount of 58% to 62% by weight, or about 60% by weight, based on the total weight of the printed porous substrate layer.

[0021] The printed porous substrate layer has a first face and a second face. Typically, the first face is opposite the second face.

[0022] The printed porous substrate layer may comprise a coating. The coating, if present, may be on either face of the printed porous substrate layer. Thus, if present, the coating typically forms the first face and / or the second face of the printed porous substrate layer.

[0023] The printed porous substrate layer comprises an ink. The ink is typically present in the printed porous layer such that it is visible when viewed from the first face of the printed porous layer. The ink may for example be present at the first face of the printed porous layer, and / or may be present in pores of the printed porous layer so as to be visible when viewed from the first face of the printed porous layer.

[0024] The ink may form a printed image, such as a decorative image. The image may be an inkjet-printed image. Inkjet printed images can be recognised by a characteristic pattern of printed dots. Thus, the ink may form a printed image (such as a decorative image) which comprises dots.

[0025] The ink comprises a pigment dispersion. The pigment dispersion comprises a pigment and a poly(vinyl chloride-vinyl acetate) copolymer binder. Unless otherwise stated, the term binder used herein typically refers to poly(vinyl chloride-vinyl acetate) copolymer binder. Unless otherwise stated, the term pigment dispersion as used herein typically refers to the pigment and the binder. However it will be understood that the pigment is typically present in the form of a dispersion throughout the entire ink.

[0026] The pigment typically has a number average particle size (Dn50) of from 0.020 μm to 0.150 μm as measured by a disc centrifuging method, for example as measured using a CPS DC24000 Disc Centrifuge Particle Size Analyser.

[0027] The pigment typically has a volume average particle size characterised by: 　　(a)　　Dv50 of from 110 to 120 nm; and / or 　　(b)　　Dv90 of less than 350 nm; 　　as measured by dynamic light scattering, for example as measured using a Malvern Zetasizer Nano-ZS Dynamic Light Scattering particle size instrument.

[0028] The binder used in the pigment dispersion is also not particularly limited. The binder comprises poly(vinyl chloride-vinyl acetate) copolymer. The poly(vinyl chloride-vinyl acetate) copolymer may have a random copolymer structure. The poly(vinyl chloride- vinyl acetate) copolymer may have an alternating copolymer structure. The poly(vinyl chloride-vinyl acetate) copolymer may have a block copolymer structure. The poly(vinyl chloride-vinyl acetate) copolymer may have a graft copolymer structure. The poly(vinyl chloride-vinyl acetate) copolymer may have a vinyl chloride:vinyl acetate monomer ratio of from 80:20 to 90:10 (typically wt:wt). The poly(vinyl chloride-vinyl acetate) copolymer may have a molecular weight (Mw) of from 40000 g mol-1to 50000 g mol-1. Molecular weight (Mw) can be measured by methods well known to a skilled person, e.g. according to ISO 16014-3:2019.

[0029] The ratio of binder (e.g. the poly(vinyl chloride-vinyl acetate) copolymer described above) to the pigment may be from 30:70 to 80:20 (typically wt:wt), e.g. from 40:60 to 60:40 (typically wt:wt), from 50:50 to 70:30 (typically wt:wt), from 40:60 to 55:45 (typically wt:wt), from 58:42 to 68:32 (typically wt:wt), from 60:40 to 66:34 (typically wt:wt), about 50:50 (typically wt:wt), about 48:52 (typically wt:wt), about 49:51 (typically wt:wt), about 44:56 (typically wt:wt), or about 63:37 (typically wt:wt).

[0030] The ink typically further comprises a solvent composition.

[0031] The ink typically does not comprise volatile, harmful, or environmentally detrimental solvents.

[0032] The ink typically does not comprise a solvent which is classified as flammable, corrosive, or harmful. One of skill in the art will understand which substances are classified as flammable, corrosive, or harmful as part of their common general knowledge, and suitable solvent classifications include those in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS); Fourth revised edition, United Nations New York and Geneva, 2011.

[0033] Preferably, the ink does not comprise one or more solvents selected from the group consisting of cyclohexanone, butyl glycol acetate, and methoxypropanol acetate.

[0034] The ink typically has desirable evaporation characteristics. The ink typically does not comprise a solvent which shows evaporation of 1% by weight or more at 30°C over 16 hours, for example as determined by the method described below: 　　-　　weigh 2 g of test material into an open container (50 mm diameter); 　　-　　place into an oven set to 30°C for a 16 hour period; and 　　-　　assess weight loss at the end of the 16 hour period.

[0035] The ink typically does not comprise a solvent which shows evaporation of 1% by weight or more at 150°C, for example as determined by the method described below: 　　-　　using a moisture analyser (e.g. Ohaus MB45), set temperature to 150°C; 　　-　　weigh 2 g of test material into pan on balance, 　　-　　close the cover. 　　-　　terminating test when amount of change is within 0.001g within 60 seconds.

[0036] Preferably, the ink does not comprise one or more solvents selected from the group consisting of cyclohexanone, butyl glycol acetate, methoxypropanol acetate, propylene glycol diacetate, and dimethyl adipate.

[0037] The solvent composition may comprise soy methyl ester. Soy methyl ester is derived from an acid (hereinafter the acid component of the soy methyl ester) and an alcohol (hereinafter the alcohol component of the soy methyl ester).

[0038] The acid component of the soy methyl ester is an unsaturated fatty acid. Preferably the acid component of the soy methyl ester is a di-unsaturated fatty acid. Di-unsaturated fatty acids may be obtained, for example, by hydrolysis of vegetable oils (e.g. soy oil). Examples of suitable di-unsaturated fatty acids include linoleic acid, eicosadienoic acid, and docosadienoic acid. Linoleic acid is preferred as the acid component of the first ester. Linoleic acid can be obtained by hydrolysis of soy oil.

[0039] The alcohol component of the first ester is a monohydric alcohol. Examples of suitable monohydric alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, i-butanol and t-butanol. Methanol is the alcohol component of the soy methyl ester.

[0040] The soy methyl ester may be an ester of a di-unsaturated fatty acid and a monohydric alcohol, and examples of the soy methyl ester include methyl esters such as linoleic acid methyl ester, eicosadienoic acid methyl ester, docosadienoic acid methyl ester and linolelaidic acid. Linoleic acid methyl ester is preferred as the soy methyl ester.

[0041] The solvent composition may further comprise an ester, glycol ester, glycol ester acetate, glycol ether, glycol ether acetate, lactone, adipate, succinate, glutarate, or a mixture thereof.

[0042] The ink of the present invention typically has a desirable viscosity for inkjet printing. Preferably, the viscosity of the ink is from 7 to 20 cP at 25°C. More preferably, the viscosity of the ink is from 8 to 14 cP at 25°C. Viscosity may be as determined using a cone and plate viscometer, such as for example a Brookfield DV3T viscometer with a CPA-40Z cone operating at 10 rpm.

[0043] In a first set of embodiments of the ink, the solvent composition comprises soy methyl ester, di-isobutyl succinate, di-isobutyl glutarate, and di-isobutyl adipate, and soy methyl ester is present in an amount of 30% to 75% by weight based on the total weight of the ink.

[0044] The pigment used in the pigment dispersion in the ink of the first set of embodiments is not particularly limited. Typically, the pigment dispersion comprises a black pigment, a blue pigment, a green pigment, a violet pigment, a red pigment, a brown pigment, a yellow pigment, or a white pigment, or a mixture thereof. The pigment may be a black pigment. The pigment may be a white pigment. The pigment may be a coloured pigment (i.e. a non- black or non-white pigment, such as cyan, red or yellow). The pigment dispersion may comprise a mixture of pigments. Preferably, the pigment dispersion comprises a pigment selected from: Pigment Black 7, Pigment Blue 15:3, Pigment Blue 60, Pigment Green 7, Pigment Violet 37, Pigment Red 144, Pigment Red 166, Pigment Red 185, Pigment Red 254, Pigment Brown 23, Pigment Yellow 83, Pigment Yellow 93, Pigment Yellow 110, Pigment Yellow 151, Pigment White 7, or a mixture thereof.

[0045] The pigment dispersion in the ink of the first set of embodiments may be a commercially available pigment dispersion. Examples of commercially available pigment dispersions that can be used in the ink of the first set of embodiments include Microlith (registered trademark)-K series (e.g. Yellow 1040 K, Yellow 1061 K, Yellow 1550 K, Yellow 2040 K, Brown 3001 K, Scarlet 3430 K, Red 3630 K, Red 3890 K, Red 4410 K, Violet 5700 K, Blue 6480 K, Blue 7080 K, Green 8750 K, Black 0066 K, and White 0022 K) available from BASF SE.

[0046] The pigment dispersion in the ink of the first set of embodiments may be present in an amount of 1 to 40 wt%, based on the total weight of the ink, for example when the pigment dispersion comprises a white pigment. The pigment dispersion may be present in the ink of the first set of embodiments in an amount of 1 to 20 wt%, based on the total weight of the ink, for example when the pigment dispersion comprises a coloured pigment.

[0047] Preferably, the pigment dispersion is present in an amount of 1 to 10 wt%, based on the total weight of the ink, such as for example 1 to 6% 1 to 4 wt%, 2 to 6%, 3 to 5%, or about 4% based on the total weight of the ink. The amounts of the pigment dispersion described above are typically the total amounts of the pigment and binder, as described above.

[0048] Typically, soy methyl ester is present in inks of the first set of embodiments in an amount of 30% to 68% by weight based on the total weight of the ink. Preferably, soy methyl ester is present in an amount of 40% to 68% by weight based on the total weight of the ink. More preferably, soy methyl ester is present in an amount of 50% to 68% by weight based on the total weight of the ink.

[0049] Typical inks of the first set of embodiments include those in which: 　　-　　the total amount of di-isobutyl succinate, di-isobutyl glutarate, and di-isobutyl adipate present in the ink is 20% to 65% by weight based on the total weight of the ink; 　　-　　soy methyl ester is present in an amount of 30% to 75% by weight based on the total weight of the ink; and 　　the pigment dispersion is present in an amount of 3 to 5% by weight based on the total weight of the ink.

[0050] Further typical inks of the first set of embodiments include those in which: 　　-　　the total amount of di-isobutyl succinate, di-isobutyl glutarate, and di-isobutyl adipate present in the ink is 28% to 59% by weight based on the total weight of the ink; 　　-　　soy methyl ester is present in an amount of 30% to 68% by weight based on the total weight of the ink; and 　　-　　the pigment dispersion is present in an amount of 3 to 5% by weight based on the total weight of the ink.

[0051] Preferred inks of the first set of embodiments include those in which: 　　-　　the total amount of di-isobutyl succinate, di-isobutyl glutarate, and di-isobutyl adipate present in the ink is 28% to 56% by weight based on the total weight of the ink; 　　-　　soy methyl ester is present in an amount of 40% to 68% by weight based on the total weight of the ink; 　　-　　the pigment dispersion is present in an amount of 3 to 5% by weight based on the total weight of the ink.

[0052] Particularly preferred inks of the first set of embodiments include those in which: 　　-　　the total amount of di-isobutyl succinate, di-isobutyl glutarate, and di-isobutyl adipate present in the ink is 28% to 46% by weight based on the total weight of the ink; 　　-　　soy methyl ester is present in an amount of 50% to 68% by weight based on the total weight of the ink; 　　-　　the pigment dispersion is present in an amount of 3 to 5% by weight based on the total weight of the ink.

[0053] Preferred cyan inks of the first set of embodiments include those in which the pigment is pigment blue 15:3 and in which: 　　-　　the total amount of di-isobutyl succinate, di-isobutyl glutarate, and di-isobutyl adipate present in the ink is 27% to 57% by weight based on the total weight of the ink; 　　-　　soy methyl ester is present in an amount of 39% to 69% by weight based on the total weight of the ink; and 　　-　　the pigment dispersion is present in an amount of 3% to 5% by weight based on the total weight of the ink.

[0054] Particularly preferred cyan inks of the first set of embodiments include those in which the pigment is pigment blue 15:3 and in which: 　　-　　the total amount of di-isobutyl succinate, di-isobutyl glutarate, and di-isobutyl adipate present in the ink is 36% to 47% by weight based on the total weight of the ink; 　　-　　soy methyl ester is present in an amount of 49% to 60% by weight based on the total weight of the ink; 　　-　　the pigment dispersion is present in an amount of 3% to 5% by weight based on the total weight of the ink.

[0055] Preferred red inks of the first set of embodiments include those in which the pigment is pigment red 166 and in which: 　　-　　the total amount of di-isobutyl succinate, di-isobutyl glutarate, and di-isobutyl adipate present in the ink is 33% to 47% by weight based on the total weight of the ink; 　　-　　soy methyl ester is present in an amount of 49% to 63% by weight based on the total weight of the ink; and 　　-　　the pigment dispersion is present in an amount of 3% to 5% by weight based on the total weight of the ink.

[0056] Particularly preferred red inks of the first set of embodiments include those in which the pigment is pigment red 166 and in which: 　　-　　the total amount of di-isobutyl succinate, di-isobutyl glutarate, and di-isobutyl adipate present in the ink is 33% to 44% by weight based on the total weight of the ink; 　　-　　soy methyl ester is present in an amount of 52% to 63% by weight based on the total weight of the ink; 　　the pigment dispersion is present in an amount of 3% to 5% by weight based on the total weight of the ink.

[0057] Preferred yellow inks of the first set of embodiments include those in which the pigment is pigment yellow 110 and in which: 　　-　　the total amount of di-isobutyl succinate, di-isobutyl glutarate, and di-isobutyl adipate present in the ink is 21% to 47% by weight based on the total weight of the ink; 　　-　　soy methyl ester is present in an amount of 49% to 75% by weight based on the total weight of the ink; and 　　-　　the pigment dispersion is present in an amount of 3% to 5% by weight based on the total weight of the ink.

[0058] Particularly preferred yellow inks of the first set of embodiments include those in which the pigment is pigment yellow 110 and in which: 　　-　　the total amount of di-isobutyl succinate, di-isobutyl glutarate, and di-isobutyl adipate present in the ink is 36% to 47% by weight based on the total weight of the ink; 　　-　　soy methyl ester is present in an amount of 49% to 60% by weight based on the total weight of the ink; 　　-　　the pigment dispersion is present in an amount of 3% to 5% by weight based on the total weight of the ink.

[0059] Preferred black inks of the first set of embodiments include those in which the pigment is pigment black 7 and in which: 　　-　　the total amount of di-isobutyl succinate, di-isobutyl glutarate, and di-isobutyl adipate present in the ink is 21% to 66% by weight based on the total weight of the ink; 　　-　　soy methyl ester is present in an amount of 30% to 75% by weight based on the total weight of the ink; and 　　-　　the pigment dispersion is present in an amount of 3% to 5% by weight based on the total weight of the ink.

[0060] Particularly preferred black inks of the first set of embodiments include those in which the pigment is pigment black 7 and in which: 　　-　　the total amount of di-isobutyl succinate, di-isobutyl glutarate, and di-isobutyl adipate present in the ink is 24% to 34% by weight based on the total weight of the ink; 　　-　　soy methyl ester is present in an amount of 62% to 72% by weight based on the total weight of the ink; 　　-　　the pigment dispersion is present in an amount of 3% to 5% by weight based on the total weight of the ink.

[0061] In a second set of embodiments of the ink, the solvent composition comprises di-isobutyl succinate, di-isobutyl glutarate, and di-isobutyl adipate, wherein the total amount of said di-isobutyl succinate, di-isobutyl glutarate, and di-isobutyl adipate is 50% or more by weight based on the total weight of the ink.

[0062] The pigment used in the pigment dispersion in the ink of the second set of embodiments is not particularly limited. Typically, the pigment dispersion comprises a red pigment, a blue pigment, or a black pigment, or a mixture thereof. The pigment may be a magenta pigment or a cyan pigment. Preferably, the pigment dispersion comprises a pigment selected from: Pigment Red 202, Pigment Red 144, Pigment Red 166, Pigment Red 185, Pigment Red 254, Pigment Blue 15:3, Pigment Blue 60, and Pigment Black 7, or a mixture thereof. More preferably the pigment dispersion comprises Pigment Red 202. Still more preferably the pigment dispersion comprises a mixture of Pigment Red 202 and one or more additional pigments selected from Pigment Red 144, Pigment Red 166, Pigment Red 185, and Pigment Red 254.

[0063] The pigment dispersion in the ink of the second set of embodiments may be a commercially available pigment dispersion. Examples of commercially available pigment dispersions that can be used in the ink of the present invention include Microlith (registered trademark)-K series (e.g. Magenta 4330 K, Magenta 4535 K, Blue 7080K, Blue 6480 K, and Black 0066K) available from BASF SE.

[0064] The pigment dispersion may be present in the ink of the second set of embodiments in an amount of 1 to 20 wt%, based on the total weight of the ink. Preferably, the pigment dispersion is present in an amount of 1 to 10 wt%, based on the total weight of the ink, such as for example 1 to 6% 1 to 4 wt%, 2 to 6%, 3 to 5%, or about 4% based on the total weight of the ink. The amounts of the pigment dispersion described above are typically the total amounts of the pigment and binder, as described above.

[0065] Soy methyl ester may be present in the ink of the second set of embodiments. Typically, if present, soy methyl ester is present in the ink of the second set of embodiments in an amount of 47% or less by weight based on the total weight of the ink, such as 1% to 47% by weight based on the total weight of the ink. Preferably, if present, soy methyl ester is present in an amount of 37% or less by weight based on the total weight of the ink, such as 1% to 37% by weight based on the total weight of the ink. More preferably, if present, soy methyl ester is present in an amount of 27% or less by weight based on the total weight of the ink, such as 1% to 27% by weight based on the total weight of the ink. Still more preferably, if present, soy methyl ester is present in an amount of 19% or less by weight based on the total weight of the ink, such as 1% to 19% by weight based on the total weight of the ink. Most preferably, soy methyl ester is not present in the ink of the second set of embodiments.

[0066] Preferred inks of the second set of embodiments include those in which: 　　-　　the total amount of di-isobutyl succinate, di-isobutyl glutarate, and di-isobutyl adipate present in the ink is 50% to 97% by weight based on the total weight of the ink; 　　-　　soy methyl ester is optionally present in the ink in an amount of 46% or less by weight based on the total weight of the ink; 　　-　　the pigment dispersion is present in an amount of 3 to 5% by weight based on the total weight of the ink.

[0067] More preferred inks of the second set of embodiments include those in which: 　　-　　the total amount of di-isobutyl succinate, di-isobutyl glutarate, and di-isobutyl adipate present in the ink is 70% to 97% by weight based on the total weight of the ink; 　　-　　soy methyl ester is optionally present in the ink in an amount of 26% or less by weight based on the total weight of the ink; 　　-　　the pigment dispersion is present in an amount of 3 to 5% by weight based on the total weight of the ink.

[0068] Particularly preferred inks of the second set of embodiments include those in which: 　　-　　the total amount of di-isobutyl succinate, di-isobutyl glutarate, and di-isobutyl adipate present in the ink is 95% to 97% by weight based on the total weight of the ink; 　　-　　soy methyl ester is not present in the ink; and 　　-　　the pigment dispersion is present in an amount of 3 to 5% by weight based on the total weight of the ink.

[0069] Inks of the first and second sets of embodiments may provide desirable viscosity stability and evaporation characteristics, and may demonstrate good nozzle recovery in inkjet printing, and typically do not utilise volatile, harmful, or environmentally detrimental solvents.

[0070] The printed porous substrate layer can be produced by providing a porous substrate comprising a polyolefin, a polyester, or a mixture thereof and applying an ink as described above thereto, e.g. by inkjet printing. A porous substrate suitable for the production of the printed porous substrate layer in this way is typically as described above with reference to the printed porous substrate layer, but does not comprise an ink. Suitable porous substrates are commercially available and include synthetic papers such as the Teslin range of synthetic papers available from PPG (e.g. Teslin IJWP substrate grades 600, 700, 800, 1000, 1200 and 1400), the Synplas range of synthetic papers available from DEP (e.g. Synplas SPQ, Synplas SPG, Synplas SPH, Synplas SPC, Synplas SPCD, Synplas SPCT, Synplas SPA, and Synplas SYPH), and the NeverTear range of synthetic papers available from Xerox. The polyvinyl chloride clear wear layer

[0071] The polyvinyl chloride clear wear layer is disposed on the first face of the printed porous substrate layer. Typically, the polyvinyl chloride clear wear layer is adhered to the first face of the printed porous substrate layer. The polyvinyl chloride clear wear layer may be directly adhered to the first face of the printed porous substrate layer, or may be adhered to the first face of the printed porous substrate layer via one or more intermediate layers.

[0072] The polyvinyl chloride clear wear layer typically has a thickness of 0.1 mm to 1.0 mm. Preferably, the polyvinyl chloride clear wear layer has a thickness of 0.2 mm to 0.8 mm. More preferably the polyvinyl chloride clear wear layer has a thickness of 0.3 mm to 0.7 mm. Still more preferably the polyvinyl chloride clear wear layer has a thickness of 0.4 mm to 0.6 mm or about 0.5 mm.

[0073] The polyvinyl chloride clear wear layer is typically transparent, and typically has a luminous transmittance of 70% or more (e.g. 70% to 99%, or 70% to 95%, or 70% to 90%). Preferably the polyvinyl chloride clear wear layer has a luminous transmittance of 80% or more (e.g. 80% to 99%, or 80% to 95%, or 80% to 90%). More preferably the polyvinyl chloride clear wear layer has a luminous transmittance of 85% or more (e.g. 85% to 99%, or 85% to 95%, or 85% to 90%). Luminous transmittance can be as measured according to ASTM D1003.

[0074] The polyvinyl chloride clear wear layer typically has a haze of 30% or less (e.g. 1% to 30%, or 5% to 30%, or 10% to 30%). Preferably the polyvinyl chloride clear wear layer has a haze of 20% or less (e.g. 1% to 20%, or 5% to 20%, or 10% to 20%). More preferably the polyvinyl chloride clear wear layer has a haze of 15% or less (e.g. 1% to 15%, or 5% to 15%, or 10% to 15%). Haze can be as measured according to ASTM D1003.

[0075] The polyvinyl chloride clear wear layer typically provides good resistance to wear. The polyvinyl chloride clear wear layer typically has a hardness (Shore A) of 70 or more (e.g. 70 to 99, or 70 to 95, or 70 to 90). Preferably the polyvinyl chloride clear wear layer has a hardness (Shore A) of 80% or more (e.g. 80 to 99, or 80 to 95, or 80 to 90). More preferably the polyvinyl chloride clear wear layer has a hardness (Shore A) of 85 or more (e.g. 85 to 99, or 85 to 95, or 85 to 90). Shore A hardness can be as measured according to BS 2782.

[0076] The polyvinyl chloride clear wear layer comprises polyvinyl chloride.

[0077] Suitable polyvinyl chloride clear wear layers are available commercially and include products which would be well known to a skilled person, e.g. as a generic "PVC Clear Wear Layer". The polyvinyl chloride backing layer

[0078] The polyvinyl chloride backing layer is disposed on the second face of the printed porous substrate layer. Typically, the polyvinyl chloride backing layer is adhered to the second face of the printed porous substrate layer. The polyvinyl chloride backing layer may be directly adhered to the second face of the printed porous substrate layer, or may be adhered to the second face of the printed porous substrate layer via one or more intermediate layers.

[0079] The polyvinyl chloride backing layer typically has a thickness of 0.5 mm to 5.0 mm. Preferably, the polyvinyl chloride clear wear layer has a thickness of 1.0 mm to 3.0 mm. More preferably the polyvinyl chloride clear wear layer has a thickness of 1.5 mm to 2.5 mm. Still more preferably the polyvinyl chloride clear wear layer has a thickness of 1.8 mm to 2.2 mm or about 2.0 mm.

[0080] The polyvinyl chloride backing layer comprises polyvinyl chloride. Typically the polyvinyl chloride backing layer comprises polyvinyl chloride in the form of PVC foam, and / or further comprises glass fibre.

[0081] When the polyvinyl chloride backing layer further comprises glass fibre, the glass fibre may be present in an amount of 80% or less (e.g. 5% to 80% or 15% to 80%), 70% or less (e.g. 5% to 70% or 15% to 70%), 60% or less (e.g. 5% to 60% or 15% to 60%), 50% or less (e.g. 5% to 50% or 15% to 50%), 40% or less (e.g. 5% to 40% or 15% to 40%), 30% or less (e.g. 5% to 30% or 15% to 30%), or 20% or less (e.g. 5% to 20% or 15% to 20%) by weight based on the total weight of the polyvinyl chloride backing layer. When the polyvinyl chloride backing layer further comprises glass fibre, the glass fibre may be present in an amount of 5% or more (e.g. 5% to 80% or 5% to 50%), 10% or more (e.g. 10% to 80% or 10% to 50%), 15% or more (e.g. 15% to 80% or 15% to 50%), 20% or more (e.g. 20% to 80% or 20% to 50%), 25% or more (e.g. 25% to 80% or 25% to 50%), 30% or more (e.g. 30% to 80% or 30% to 50%), or 35% or more (e.g. 35% to 80% or 35% to 50%) by weight based on the total weight of the polyvinyl chloride backing layer.

[0082] The polyvinyl chloride clear backing typically has a hardness (Shore A) of 70 or more (e.g. 70 to 99, or 70 to 95, or 70 to 90). Preferably the polyvinyl chloride backing layer has a hardness (Shore A) of 80% or more (e.g. 80 to 99, or 80 to 95, or 80 to 90). More preferably the polyvinyl chloride backing layer has a hardness (Shore A) of 85 or more (e.g. 85 to 99, or 85 to 95, or 85 to 90). Methods for forming multilayer structure

[0083] The present invention provides a method for producing a multilayer structure of the present invention, as described above, comprising: 　　-　　providing a printed porous substrate layer having first and second faces, providing a polyvinyl chloride clear wear layer on the first face of the printed porous substrate layer, and providing a polyvinyl chloride backing layer on the second layer of the printed porous substrate layer to form an intermediate multilayer structure; wherein the printed porous substrate layer, polyvinyl chloride clear wear layer, and polyvinyl chloride backing layer are as described above with reference to the multilayer structure of the present invention; and 　　-　　heating the intermediate multilayer structure to a temperature in the range of 130°C to 150°C; 　　to form a multilayer structure of the present invention.

[0084] The step of heating the intermediate multilayer structure to a temperature in the range of 130°C to 150°C may, for example, comprise heating the intermediate multilayer structure to a temperature in a range of 130°C to 140°C, 135°C to 145°C, 140°C to 150°C, 130°C to 135°C, 135°C to 140°C, 140°C to 145°C, or 145°C to 150°C.

[0085] The step of heating the intermediate multilayer structure may cause the polyvinyl chloride clear wear layer to adhere (e.g. directly adhere) to the first face of the printed porous substrate layer, and / or may cause the polyvinyl chloride backing layer to adhere (e.g. directly adhere) to the second face of the printed porous substrate layer.

[0086] In the method of the present invention, providing a printed porous substrate layer may comprise providing a porous substrate comprising a polyolefin, a polyester, or a mixture thereof, and applying an ink thereto by inkjet printing, wherein the ink is as described above with reference to the multilayer structure of the present invention. Article of Flooring

[0087] The present invention provides an article of flooring comprising a multilayer structure of the present invention. The article of flooring of the present invention may be in the form of a tile, a plank or a sheet.

[0088] The invention is illustrated below by means of the following non-limiting examples.Examples Example 1

[0089] An ink comprising a Microlith pigment dispersion was inkjet printed onto a TESLIN (registered trademark) IJWP1000 porous polymer substrate layer. The ink level was 100%. The printed polymer substrate layer thus obtained was laminated with a PVC wear layer and a vinyl backing layer at a temperature between 130°C to 150°C to obtain a multilayer structure. Example 2

[0090] A multilayer structure was prepared in the same way as in Example 1, except the ink level was 200%. Comparative Example 1

[0091] A liquid plastisol coat was applied to a carrier substrate, and an oil-based ink was inkjet printed onto the liquid plastisol (wet-on-wet printing). The ink level was 100%. The printed liquid coat was cured at a temperature between 130°C to 200°C. The carrier substrate was removed and the cured printed plastisol layer was laminated with a PVC wear layer and a PVC backing layer at a temperature between 150°C to 190°C to obtain a multilayer structure. Comparative Example 2

[0092] A multilayer structure was prepared in the same way as in Comparative Example 1, except the ink level was 200%. Peel Test

[0093] The multilayer structures of Examples 1 and 2 and Comparative Examples 1 and 2 were subjected to a peel test using the following procedure.

[0094] The peel test is undertaken on Testometric μ350 tensile tester. A 25mm sample is pulled between two jaws (PVC wear layer and printed substrate in one jaw and PVC backing layer in the other jaw at a 180° angle) on the tester at 100 mm / min. The force is measured in Newtons (N). The peel result units are N / cm. The target for adequate bond strength in a laminate flooring article is 10 N / cm or more.

[0095] Results are given in the table below

[0096] As can be seen from the test results above, the multilayer structures of Examples 1 and 2 provided above-target bond strength, and in both cases were superior to the comparative plastisol-based structure.

[0097] The present application is based on and claims priority of Great British Patent Application No. 2314902.4 filed on September 28, 2023, Great British Patent Application No. 2314905.7 filed on September 28, 2023, and Great British Patent Application No. 2314906.5 filed on September 28, 2023, the entire contents of which are hereby incorporated herein by reference.

Claims

1. A multilayer structure comprising: 　　　　(1)　　a printed porous substrate layer having first and second faces; 　　　　(2)　　a polyvinyl chloride clear wear layer disposed on the first face of the printed porous substrate layer; and 　　　　(3)　　a polyvinyl chloride backing layer disposed on the second layer of the printed porous substrate layer; and 　　wherein said printed porous substrate layer comprises (i) a polyolefin, a polyester, or a mixture thereof; and (ii) an ink comprising a pigment dispersion; 　　and wherein said pigment dispersion comprises a pigment and a poly(vinyl chloride-vinyl acetate) copolymer binder.

2. A multilayer structure according to claim 1, wherein the printed porous substrate layer has a melting point of 135°C or more.

3. A multilayer structure according to claim 1 or claim 2, wherein the printed porous substrate layer comprises a silica filler.

4. A multilayer structure according to any one of claims 1 to 3, wherein the printed porous substrate layer has a porosity of 45% to 85%.

5. A multilayer structure according to any one of claims 1 to 4, wherein the ink further comprises a solvent composition, wherein said solvent composition comprises soy methyl ester, di-isobutyl succinate, di-isobutyl glutarate, and di-isobutyl adipate, said soy methyl ester being present in an amount of 30% to 75% by weight based on the total weight of the ink.

6. A multilayer structure according to any one of claims 1 to 4, wherein the ink further comprises a solvent composition, wherein said solvent composition comprises di-isobutyl succinate, di-isobutyl glutarate, and di-isobutyl adipate, and wherein the total amount of said di-isobutyl succinate, di-isobutyl glutarate, and di-isobutyl adipate is 50% or more by weight based on the total weight of the ink.

7. A multilayer structure according to one of claims 1 to 6, wherein the polyvinyl chloride clear wear layer is adhered to the first face of the printed porous substrate layer and the polyvinyl chloride backing layer is adhered to the second layer of the printed porous substrate layer.

8. A multilayer structure according to any one of claims 1 to 7, wherein the polyvinyl chloride clear wear layer has a thickness of 0.1 mm to 1.0 mm.

9. A multilayer structure according to any one of claims 1 to 8, wherein the polyvinyl chloride backing layer has a thickness of 0.5 mm to 5.0 mm.

10. A multilayer structure according to any one of claims 1 to 9, wherein the polyvinyl chloride backing layer comprises polyvinyl chloride in the form of polyvinyl chloride foam, and / or further comprises glass fibre.

11. A method for producing a multilayer structure according to any one of claims 1 to 10, comprising: 　　　　-　　providing a printed porous substrate layer having first and second faces, providing a polyvinyl chloride clear wear layer on the first face of the printed porous substrate layer, and providing a polyvinyl chloride backing layer on the second layer of the printed porous substrate layer to form an intermediate multilayer structure; wherein the printed porous substrate layer, polyvinyl chloride clear wear layer, and polyvinyl chloride backing layer are as defined in any one of claims 1 to 10; and 　　　　-　　heating the intermediate multilayer structure to a temperature in the range of 130°C to 150°C; 　　to form a multilayer structure as defined in any one of claims 1 to 10.

12. A method according to claim 11, wherein providing a printed porous substrate layer comprises providing a porous substrate comprising a polyolefin, a polyester, or a mixture thereof, and applying an ink thereto by inkjet printing, wherein the ink is as defined in any one of claims 1 to 10.

13. An article of flooring comprising a multilayer structure as defined in any one of claims 1 to 10.

14. An article of flooring as defined in claim 13, which is in the form of a tile, a plank or a sheet.

Images