Printed substrate and method for printing onto a substrate
阅读说明：本技术 打印的基底和用于打印到基底上的方法 (Printed substrate and method for printing onto a substrate ) 是由 J.哈米尔顿 A.麦克维蒂 D.史密斯 S.戴维斯 于 2019-09-09 设计创作，主要内容包括：公开了用于打印到基底上的方法。将墨打印到液体聚合物层上以形成打印的聚合物层。还公开了打印的基底。(A method for printing onto a substrate is disclosed. Printing ink onto the liquid polymer layer to form a printed polymer layer. Printed substrates are also disclosed.)
1. Method for printing onto a substrate, comprising the following steps
Applying an aqueous polymer dispersion to a substrate to form a liquid aqueous polymer layer, wherein the aqueous polymer dispersion comprises water and a polymer;
printing an ink onto the liquid aqueous polymer layer to form a printed aqueous polymer layer, wherein the ink comprises a colorant and whereby the printed aqueous polymer layer comprises the colorant; and
drying the printed aqueous polymer layer to change the printed aqueous polymer layer from a liquid to a solid.
2. The method of claim 1, wherein the polymer is one or more polymers selected from the group consisting of: polyvinyl chloride, copolymers of vinyl chloride and vinyl acetate, terpolymers of vinyl chloride, vinyl acetate and ethylene, and alkyd resins.
3. The method according to claim 1 or 2, wherein the substrate is selected from a polyvinyl chloride substrate, an aluminum substrate, a cardboard substrate or a wooden substrate.
4. The method of any one of claims 1-3, wherein the aqueous polymer dispersion further comprises a surfactant.
5. The method of claim 4, wherein the surfactant is one or more surfactants selected from the group consisting of acetylenic diols, fluorocarbon surfactants, and modified siloxanes.
6. The method of any one of claims 1-5, wherein the aqueous polymer dispersion comprises a viscosity modifier.
7. The method of claim 6, wherein the viscosity modifier is one or more viscosity modifiers selected from polyacrylic acid derivatives and polyhydric alcohols.
8. The method of any one of claims 1-7, wherein the aqueous polymer dispersion comprises a filler selected from the group consisting of calcium carbonate, talc, barytes, and mica.
9. The method of claim 8, wherein the filler is ground calcium carbonate.
10. The method of any of claims 1-9, wherein the aqueous polymer dispersion comprises at least 30 wt% polymer and less than 80 wt% polymer, based on the weight of the aqueous polymer dispersion.
11. A printed substrate comprising a printed polymer layer on a substrate, wherein the printed polymer layer comprises a colorant and a polymer.
12. The printed substrate of claim 11, wherein the polymer in the printed polymer layer is selected from one or more of the following: polyvinyl chloride, copolymers of vinyl chloride and vinyl acetate, and terpolymers of vinyl chloride, vinyl acetate and ethylene.
13. The printed substrate of claim 11, wherein the polymer in the printed polymer layer is an alkyd.
14. The printed substrate according to any one of claims 11-13, wherein the substrate is selected from a polyvinyl chloride substrate, an aluminum substrate, a cardboard substrate, or a wooden substrate.
15. The printed substrate of any one of claims 11-14, wherein the printed polymer layer comprises a surfactant selected from the group consisting of acetylenic diols, fluorocarbon surfactants, and modified siloxanes.
16. The printed substrate of any one of claims 11-15, wherein the printed polymer layer comprises a viscosity modifier selected from polyacrylic acid derivatives and polyhydric alcohols.
17. The printed substrate of any one of claims 11-16, wherein the printed polymer layer comprises a filler selected from the group consisting of calcium carbonate, talc, barytes, and mica.
18. The printed substrate of claim 17, wherein the filler is ground calcium carbonate.
Technical Field
The present invention relates to a printed substrate and a method for printing onto a substrate.
Background
Inkjet printing is used in a variety of printing applications and can provide high resolution pigmented (colored) images on a range of substrates. Advantageously, the inkjet printing process provides high quality durable images. The process should achieve high optical density so that the amount of ink required to achieve the desired image is minimized. In addition, the ink should adhere to the substrate so that the image is rub resistant.
In recent years, inkjet printing has been used in wallpaper production. In addition to the printed pattern, the wallpaper typically has a resin layer that provides scratch and stain resistance and also affects the appearance of the wallpaper. WO2018/110518 describes a printing process that can be used to prepare surface coverings such as wallpaper. In the disclosed method, a liquid resin layer is applied to a substrate and a pattern is applied to the liquid resin layer by ink jet printing. The patterned layer of liquid resin then undergoes curing such that the layer of liquid resin undergoes a phase change from liquid to solid. In the examples, the liquid plastisol resin layer composition was applied to a paper (fleece-backed paper) with a fleece backing. The plastisol composition is a dispersion of polyvinyl chloride polymer in an ester-based plasticizer.
CITATION LIST
Patent document
[PTL 1]WO 2018/110518
Disclosure of Invention
Technical problem
The present inventors have sought to make further improvements in printed substrates and printing processes. In particular, the present inventors have sought to provide printed substrates having high quality durable images.
Solution to the problem
Accordingly, the present invention provides a method for printing onto a substrate comprising the steps of
Applying an aqueous polymer dispersion to a substrate to form a liquid aqueous polymer layer, wherein the aqueous polymer dispersion comprises water and a polymer;
printing an ink onto the liquid aqueous polymer layer to form a printed aqueous polymer layer, wherein the ink comprises a colorant and thus the printed aqueous polymer layer comprises the colorant; and
drying the printed aqueous polymer layer to change the printed aqueous polymer layer from a liquid to a solid.
The inventors have found that printing onto a liquid aqueous polymer layer can provide a substrate bearing the polymer layer and a high quality and durable printed image. In particular, the inventors have found that printing exhibits good dot spreading and dot penetration as long as the aqueous layer is liquid when printing is performed. The printed layer is dried such that water evaporates from the layer and the polymer in the layer coalesces. The resulting printed layer has high optical density and is rub resistant.
Unlike the process of WO2018/110518, in which a polymer dispersed in a plasticizer is used, followed by subsequent curing to form a polymer layer, the method of the present invention uses an aqueous polymer dispersion. The inventors have found that printing onto the liquid aqueous polymer layer can provide a printed layer with advantageous dot shape and uniformity of dot size and shape, resulting in a high quality image. The printed image is durable and exhibits effective rub resistance. Furthermore, the present process benefits from the environmental advantages of using water-based (aqueous-based) components instead of the prior art plasticizer-based components.
The present invention further provides a printed substrate comprising a printed polymer layer on a substrate, wherein the printed polymer layer comprises a colorant and a polymer. Different substrates can be used, but preferred substrates have a surface made of wood, polymer (e.g. polyvinyl chloride) or metal (e.g. aluminium). The printed substrate is obtainable by the method of the invention. The printed substrate differs from the substrate typically obtained via the process of WO2018/110518 in that: it will not contain any plasticizer brought about by the plastisol resin, and the nature of the image will differ due to the difference in the interaction of the ink with the liquid aqueous polymer layer as compared to the interaction of the ink with the uncured plastisol layer. In the printed substrates of the present invention, the polymer in the printed polymer layer may advantageously be selected such that it preferentially adheres to the selected substrate. Depending on the type of substrate, different polymers and polymer blends will be preferred.
Drawings
Fig. 1 schematically depicts an example method of printing onto a substrate of the present invention.
Fig. 2 is a photomicrograph of a printed substrate made by a method according to the present invention.
Fig. 3 is a photomicrograph of a printed substrate made by a method according to the prior art.
Detailed Description
The method of the present invention is used to print onto a substrate. The substrate may be formed of paper, nonwoven fabric, plastic, wood, metal, or a combination of these materials. Specific examples may be selected from natural paper, plastic film, synthetic paper, non-woven fabric, fleece (cloth), cloth (cloth), wood, semi-cured wallpaper, wherein the solid resin layer is present in the form of a semi-gel, fully cured wallpaper, metal sheet (metal plate) and metal film or any combination of these materials. In a preferred embodiment, the substrate comprises paper with a fleece backing. In another embodiment, the substrate is semi-rigid polyvinyl chloride suitable for use in flooring applications. In yet another embodiment, the substrate is polyethylene suitable for packaging applications.
A multi-layer substrate may be used. Preferably, the top layer of the substrate, onto which the aqueous polymer dispersion is applied, is selected from paper, plastic film (e.g. polyvinyl chloride), wood or metal (e.g. aluminium).
The process of the present invention may comprise a further step in which the substrate is pretreated prior to applying the aqueous polymer dispersion to the substrate. Such pre-treatment steps may include cleaning of the substrate (e.g., wiping with a cloth or by applying a cleaning liquid) or smoothing of the substrate surface (e.g., sanding with an abrasive material such as sandpaper). For example, prior to application of the aqueous polymer dispersion, the sheet metal substrate can be degreased, the polymer film substrate can be corona or plasma treated, and the wooden substrate can be cleaned to remove dust.
In aqueous polymer dispersions, a dispersed phase of polymer particles is present in an aqueous continuous phase. The continuous phase may comprise other components in addition to water.
The aqueous polymer dispersion suitably comprises at least 10 wt% water, based on the weight of the aqueous polymer dispersion. Preferably, the aqueous polymer dispersion comprises at least 20 wt% water, more preferably at least 30 wt% water and most preferably at least 40 wt% water, based on the weight of the polymer dispersion. The continuous phase of the aqueous polymer dispersion preferably comprises at least 50 wt% water, more preferably at least 75 wt% water and most preferably at least 95 wt% water, based on the weight of the aqueous polymer dispersion minus the solid phase. It is preferred to maximize the water content of the continuous phase because water is easy to remove and is environmentally friendly.
The pH of the aqueous polymer dispersion is suitably between 4.0 and 9.0, more preferably between 6.0 and 7.5.
The aqueous polymer dispersion suitably comprises at least 10 wt% polymer, based on the weight of the aqueous polymer dispersion. Preferably, the aqueous polymer dispersion comprises at least 20 wt% polymer, more preferably at least 30 wt% polymer and most preferably at least 40 wt% polymer. Preferably, the aqueous polymer dispersion comprises less than 80 wt% polymer, more preferably less than 70 wt% polymer. The dispersed phase of the aqueous polymer dispersion preferably comprises at least 90 wt% polymer, more preferably at least 95% polymer and most preferably at least 99 wt% water, based on the solids content of the aqueous polymer dispersion. If the amount of polymer in the aqueous polymer dispersion is too low, this may lead to slow drying. The amount of polymer will also affect the viscosity of the aqueous polymer dispersion and the properties of the resulting liquid aqueous polymer layer.
The polymer particles which constitute the dispersed phase in the aqueous polymer dispersion suitably have an average particle size of between 50nm and 5000nm, preferably between 100nm and 2500nm and more preferably between 100nm and 1000 nm. A narrower particle size range is preferred as this may improve the stability of the liquid aqueous polymer layer (i.e. reduce the likelihood of the layer separating into different phases). The average particle size (suitably volume-averaged) can be measured by techniques such as laser diffraction, dynamic light scattering and single particle optical fractionation. The amount of polymer particles per litre of dispersion is suitably 104To 109And (4) particles. This can be measured by single particle optical fractionation.
The polymer in the dispersed phase is suitably derived fromOne or more polymers of the body: vinyl chloride, vinyl acetate, ethylene, styrene, acrylic acid ester (CH)2CHCOOR, wherein R is suitably C1-10Alkyl), methacrylic acid and methacrylate (CH)2C(CH3) COOR ', wherein R' is suitably C1-10Alkyl groups). Preferred polymers include polyvinyl chloride (PVC), copolymers of vinyl chloride and vinyl acetate, and terpolymers of vinyl chloride, vinyl acetate, and ethylene. Vinyl-based polymers are typically inexpensive. Polymers comprising ethylene monomers benefit from internal plasticization, which is a property of ethylene monomer units. This internal plasticization avoids the use of liquid plasticizers, which can be expensive and can migrate from the polymer layer.
Alternatively, the polymer in the dispersed phase is suitably an alkyd resin. Alkyd resins are polyesters formed from the polymerization reaction between a polyhydric alcohol and a polyfunctional acid. Suitable polyhydric alcohols include glycerol, trimethylolethane, trimethylolpropane and pentaerythritol. Suitable polyfunctional acids include phthalic anhydride, isophthalic acid, fumaric acid, and maleic anhydride. The properties of the alkyd resin are suitably controlled by the addition of vegetable oils to the polymerisation reaction. Alkyd resins have the following advantages: they are stable, low cost, and easily modified to provide a range of hardness and drying times.
In one embodiment of the invention, the polymer in the dispersed phase may comprise a monomer capable of crosslinking. Suitable monomers include acrylamide, N-methylolacrylamide, acrylic acid and methacrylic acid. GB 2226564 describes photopolymerizable grafted polyvinyl alcohol resins comprising dispersed ethylenically unsaturated materials, which can be used as polymers in the aqueous polymer dispersions of the present invention. The crosslinked polymer layer may have improved durability.
Suitable aqueous polymer dispersions are readily available as commercial products. For example, VilaquaTMThe resin is available from Vil Resins Ltd and is a dispersion of an alkyd resin. VinnolTMAnd VinnapasTMThe resin is a copolymer and terpolymer derived from vinyl chloride, vinyl acetate and/or ethyleneAnd is available from Wacker Chemie AG. Another suitable dispersion is MowilithTMVC600 (copolymer of vinyl acetate and vinyl chloride) and RevacrylTM826 (acrylic copolymer).
In one embodiment of the invention, the aqueous polymer dispersion is formed from a blend of two or more aqueous polymer dispersions. Blending two or more aqueous polymer dispersions enables the skilled person to optimize the properties of the liquid aqueous polymer layer formed. In particular, the skilled person can adjust the polymer properties depending on the substrate used.
The viscosity of the aqueous polymer dispersion is suitably from 10 to 2000mPas, preferably from 20 to 1500mPas, more preferably from 40 to 1000mPas and most preferably from 100 to 500 mPas. The viscosity is suitably measured using a Brookfield DV-III Ultra Programmable Rheometer. The viscosity of the aqueous polymer dispersion will affect the viscosity of the liquid aqueous polymer layer. The viscosity of the liquid aqueous polymer layer will affect the penetration of the ink into the polymer layer. If the viscosity of the liquid aqueous polymer layer is too low, spreading of the ink on the polymer layer may be insufficient, resulting in a low optical density.
The surface tension of the aqueous polymer dispersion is suitably from 20 to 50 dynes/cm. This can be measured on a Drop Shape Analyser, such as any of the Drop Shape analyzers available from Kruss GmbH.
It may be advantageous to include additional components in the aqueous polymer dispersion. Suitable components may include surfactants, viscosity modifiers, fillers or cross-linking agents. The surfactant may act as a wetting agent, leveling agent (leveling agent), dispersant and defoamer.
The incorporation of surfactants in the aqueous polymer dispersion alters the surface tension of the liquid aqueous polymer layer formed. The surface tension affects how the ink penetrates the liquid aqueous polymer layer, so that the addition of a surfactant can improve dot spreading or dot penetration of the printing step. The surfactant may be an acetylenic diol-based material (e.g., Surfynol available from Evonik)TMStages). These have optimal activity at the solid/liquid interfaceAnd can be particularly useful for imparting optimal coating of the aqueous polymer dispersion to a substrate. The surfactant may also be a fluorocarbon surfactant, such as Capstone from DuPontTMThose in the series and PolyFox from OmnovaTMMaterials in the series. This type of surfactant is particularly useful for imparting optimal print coverage on the surface of aqueous polymer dispersions. Other suitable surfactants include modified siloxanes available from BYK Chemie. Suitably, the surfactant is present in the aqueous polymer dispersion in an amount of from 0.005 to 2 wt%, preferably from 0.01 to 1.00 wt%, based on the weight of the aqueous polymer dispersion. The amount of surfactant should be the minimum amount necessary to achieve the desired surface tension change, thereby minimizing costs.
The incorporation of a viscosity modifier in the aqueous polymer dispersion will modify the viscosity of both the aqueous polymer dispersion and the liquid aqueous polymer layer formed. This can have beneficial results for the application of the aqueous polymer dispersion and also for the spreading of the ink on the liquid aqueous polymer layer. The viscosity modifier may be selected from polyacrylic acid derivatives such as Junlon from ToagoseiTM、AronTM、JurymerTMAnd RheogicTMAnd Carbopol from LubrizolTM. This type of modifier imparts viscosity to various types of systems, achieves rheology adjustment and improves flowability. TexipolTMInverse emulsion thickeners are versatile in that they impart a viscosity effect only after the inverse emulsion is directly inverted in the system being thickened. Various polyhydric alcohols such as glycerol, polyethylene glycol and polypropylene glycol may also be used. Suitably, the viscosity modifier is present in the aqueous polymer dispersion in an amount of from 0.05 to 15 wt%, preferably from 0.1 to 10 wt%, based on the weight of the aqueous polymer dispersion. The amount of viscosity (modifier) should be the minimum amount required to achieve the desired viscosity, thereby minimizing costs.
The incorporation of fillers in aqueous polymer dispersions can achieve a number of benefits. The filler may impart improved mechanical properties to the polymer layer, or it may impart color or opacity to the polymer layer. Fillers can also alter the surface appearance of the dried polymer layer. The addition of fillers can alter the surface properties of the liquid aqueous polymer, which can lead to improved image properties such as better dot spread properties. Suitable fillers include calcium carbonate (ground and/or precipitated), talc (magnesium silicate), barite (barium sulfate), mica (aluminum sulfate), alumina and other aluminum-based minerals. Preferred fillers are calcium carbonate, talc, barytes and mica. Suitably, the filler is present in the aqueous polymer dispersion in the range of from 1 wt% to 20 wt%, preferably from 2 wt% to 15 wt%, based on the weight of the aqueous polymer dispersion. Fillers are typically inexpensive components of aqueous polymer dispersions and thus there is no need to minimize the amount of filler.
The incorporation of a cross-linking agent in the aqueous polymer dispersion may provide a polymer layer with improved durability, which may mean advantageous properties such as excellent gloss, improved water resistance, improved weather resistance (UV and heat resistance) and improved rub resistance. Preferred crosslinking agents are diisocyanate agents.
The aqueous polymer dispersion is applied to a substrate to form a liquid aqueous polymer layer. The aqueous polymer layer is "liquid" in that the material forming the layer can conform to the shape of its container. Whether the material is a liquid or a solid can be tested as follows. A 50ml sample of the material was placed in an open (open-topped) container. The surface of the sample is deformed by taking a portion by removing 5ml of the sample with a spatula. The sample was allowed to stand for 6 hours. If the deformed portion does not return to the previous state, it is a gel; if it does return to the previous state, it is liquid.
To ensure that the aqueous polymer layer is liquid, it is necessary to print shortly after the aqueous polymer dispersion has been applied. If too much time passes between application and printing of the aqueous polymer dispersion, water can evaporate from the aqueous polymer layer such that it is no longer a liquid. Preferably, the time period between application and printing of the aqueous polymer dispersion is less than 4 hours, more preferably less than 1 hour and most preferably less than 10 minutes. If the process of the present invention is carried out on a continuous production line, the time period between application and printing of the aqueous polymer dispersion may suitably be less than 1 minute.
The aqueous polymer dispersion is applied by any suitable method. For example, the dispersion may be applied by: screen printing (flatbed or rotary), roll coating with metering rolls or doctor bars, gravure printing or coating line processes (e.g. slot, extrusion, slide and curtain coating).
The thickness of the liquid aqueous polymer layer is suitably from 5 to 100 microns, preferably from 12 to 50 microns.
Suitably, the printing is by a droplet printing process (preferably inkjet printing). The printed aqueous polymer layer may be printed using any suitable inkjet printing apparatus. For example, a RICOH Pro 4130 (trade name) wide format latex color press may be used. The ink jet print head is suitably heatable to control the viscosity of the ink jet ink. For example, it may be heated to a temperature in the range of 30 ℃ to 60 ℃, most preferably about 45 ℃.
Preferably, at least two colors are printed. According to normal ink jet printing technology, first a first colour of ink is applied and subsequently at least a second colour of ink is applied. Full color inkjet printing can be used. Conventional black, cyan, magenta, and yellow print heads can be used.
The printed aqueous polymer layer is suitably printed using an oil-based ink. The oil-based ink preferably includes a carrier such as an oily component, and a colorant. The oil-based ink may optionally include a binder resin.
Preferably, the oily component is an ester oil. Suitable ester oils include phthalate esters such as dibutyl phthalate, dioctyl phthalate, diisodecyl phthalate, Dioctyl Phthalate (DPO), diisononyl phthalate, butyl-2-ethylhexyl phthalate and di-2-ethylhexyl phthalate; adipates, such as dioctyl adipate (diethylhexyl adipate: DOA) and diisononyl adipate (DINA); sebacates such as dibutyl sebacate, dioctyl sebacate and diisononyl sebacate; citrates, such as acetyl tributyl citrate (ATBC); azelaic acid esters such as dibutyl azelate, dioctyl azelate and diisononyl azelate; lauric acid esters such as methyl laurate, ethyl laurate, and isobutyl laurate; myristates such as isopropyl myristate, isocetyl myristate and octyldodecyl myristate; palmitate esters, such as isopropyl palmitate and octyl palmitate; octanoates, such as cetyl octanoate, octyl octanoate (ethylhexyl ethylhexanoate: OOE), and isononyl octanoate; and isononanoates, such as ethylhexyl isononanoate and isononyl isononanoate.
The viscosity of the oily component at 45 ℃ is preferably in the range of 5 to 30mPas, more preferably 8 to 18mPas, most preferably 10 to 12 mPas. The viscosity is preferably measured using a Brookfield DV-III Ultra Programmable Rheometer.
Preferably, the oil-based ink comprises less than 1% by weight, and more preferably less than 0.1% by weight, of volatile organic compound solvent. The volatile organic compound solvent is an organic compound having a vapor pressure of 0.01kPa or greater at 293.15K as defined by EU directional 1999/13/ec (solvent emulsions directional).
Preferably, the oil-based ink is non-aqueous. Preferably, the water content in the oil-based ink is less than 1% by weight, more preferably less than 0.1% by weight, based on the weight of the oil-based ink.
Specific examples of the colorant included in the oil-based ink include carbon black, pigments such as azo-based pigments, phthalocyanine pigments, nitroso pigments, nitro pigments, vat pigments, mordant pigments, basic dye pigments, acid dye pigments, and natural dye pigments; and oil-soluble dyes such as disazo-based dyes and anthraquinone dyes. Each of these dyes and pigments may be used alone or in combination with the others.
The printed aqueous polymer layer is dried. Drying may be carried out at ambient temperature, but suitably the printed aqueous polymer layer is heated to effect evaporation of water from the layer. During the drying step, the printed aqueous polymer layer changes from a liquid to a solid. The polymer particles from the dispersed phase coalesce to form a solid polymer layer. The drying is suitably carried out at a temperature in the range of from 100 ℃ to 200 ℃. The duration of the drying step is suitably from 10 seconds to 10 minutes.
An additional finishing step may optionally be performed after the drying step. Such finishing steps may include blowing, embossing, over-coating and/or lamination. The finishing step may add decoration to the dried polymer layer, or may add additional protection.
Figure 1 schematically depicts an example of the method of the present invention. The aqueous polymer dispersion is applied to a substrate (1) to form a liquid aqueous polymer layer (2). Forming a printed aqueous polymer layer (2, 4) by printing (3) onto the liquid aqueous polymer layer (2). Heating (5) the printed aqueous polymer layer so that water evaporates and the polymer coalesces, thereby changing the aqueous polymer layer from a liquid to a solid polymer (6).
The invention further provides a printed substrate. The printed substrate is obtainable by the method according to the invention. The printed substrate includes a printed polymer layer on the substrate. The printed polymer layer includes a colorant. Suitable colorants are as described above. The printed layer includes a polymer.
In one embodiment, the polymer in the printed polymer layer is suitably a polymer derived from one or more of the following monomers: vinyl chloride, vinyl acetate, ethylene, styrene, acrylic acid ester (CH)2CHCOOR, wherein R is suitably C1-10Alkyl), methacrylic acid and methacrylate (CH)2C(CH3) COOR ', wherein R' is suitably C1-10Alkyl groups). Preferred polymers include polyvinyl chloride (PVC), copolymers of vinyl chloride and vinyl acetate, terpolymers of vinyl chloride, vinyl acetate and ethylene, and alkyd resins.
In a preferred embodiment, the polymer in the printed polymer layer comprises an alkyd resin (and suitably comprises at least 50% by weight alkyd resin, based on the weight of the polymer in the printed polymer layer).
The substrate is preferably selected from a wood substrate, a polymer substrate, a metal substrate, or a cardboard or paper substrate. The polymer in the printed polymer layer may advantageously be selected such that it preferentially adheres to the selected substrate. Depending on the material of the substrate, different polymers and polymer blends will be preferred.
A multi-layer substrate may be used. Preferably, the base top layer (adjacent to the printed polymer layer) is selected from paper, plastic film (e.g. polyvinyl chloride), wood or metal (e.g. aluminium).
The printed polymer layer may include a surfactant. The surfactant may be an acetylenic diol-based material (e.g., Surfynol available from Evonik)TMStages). The surfactant may also be a fluorocarbon surfactant, such as Capstone from DuPontTMThose in the series and PolyFox from OmnovaTMMaterials in the series. Other suitable surfactants include modified siloxanes available from BYK Chemie. The surfactant is suitably present at 0.01 wt% to 2 wt% based on the weight of the printed polymer layer.
The printed polymer layer may include a viscosity modifier. The viscosity modifier may be selected from polyacrylic acid derivatives, such as Junlon from ToagoseiTM、AronTM、JurymerTMAnd RheogicTMAnd Carbopol from LubrizolTM. Various polyhydric alcohols such as glycerol, polyethylene glycol and polypropylene glycol may also be used. The viscosity modifier is suitably present at from 0.1 wt% to 5 wt% based on the weight of the printed polymer layer.
The printed polymer layer may include a filler. Suitable fillers include calcium carbonate (ground and/or precipitated), talc (magnesium silicate), barite (barium sulfate), mica (aluminum sulfate), alumina and other aluminum-based minerals. Preferred fillers are calcium carbonate, talc, barytes and mica, most preferably ground calcium carbonate. The filler is suitably present at 0.5 wt% to 10 wt% based on the weight of the printed polymer layer.
In one embodiment of the invention, the substrate is a wood substrate. In a preferred embodiment, the substrate is a wood substrate and the polymer in the printed layer comprises an alkyd polymer. More preferably, the polymer in the printed layer comprises at least 50 wt% alkyd polymer, based on the weight of the polymer in the printed layer. In a further embodiment of the invention, the substrate is a polymeric substrate, preferably a polyvinyl chloride substrate. In a preferred embodiment, the substrate is a polyvinyl chloride based substrate and the polymer in the printed layer comprises a copolymer of polyvinyl chloride and vinyl acetate. More preferably, the polymer in the printed layer comprises at least 50 wt% of a copolymer of polyvinyl chloride and vinyl acetate, based on the weight of the polymer in the printed layer.
In a further embodiment of the invention, the substrate is a metal substrate, preferably an aluminum substrate. In a preferred embodiment, the substrate is an aluminum substrate and the polymer in the printed layer comprises an alkyd polymer. More preferably, the polymer in the printed layer comprises at least 50 wt% alkyd polymer, based on the weight of the polymer in the printed layer.
In a further embodiment of the invention, the substrate is a paper or cardboard substrate. In a preferred embodiment, the substrate is a paper or cardboard substrate and the polymer in the printed layer comprises a copolymer of polyvinyl chloride and vinyl acetate. More preferably, the polymer in the printed layer comprises at least 50 wt% of a copolymer of polyvinyl chloride and vinyl acetate, based on the weight of the polymer in the printed layer.
The following non-limiting examples are illustrative of the present invention.
Examples 1 to 26
In various embodiments, the aqueous polymer dispersion is applied to a substrate. The ink is printed onto the liquid polymer layer. The printed layer was dried at 130 ℃. Table 1 shows the type of polymer dispersion used. The alkyd resin was Vilaqua from Vil Resins LtdTM615a 55. Vinyl chloride copolymer dispersion is Vinnol from Wacker Chemie AGTMCE 35. Table 1 also indicates whether any additives are included in the aqueous polymer dispersion, the nature of the substrate, and the color of the ink. The optical density and durability of the printed image were also recorded. The optical concentration was measured using an X-Rite 508 concentration meter. Durability was evaluated using a finger rub test. DurableThe permanence is given in the following scale: 5 (excellent), 4 (good), 3 (good), 2 (general), or 1 (poor).
[ Table 1]
All polymer dispersions are aqueous and therefore the process is environmentally advantageous when compared to prior art processes using plasticizer based polymer systems.
The printed images produced in these examples had good optical density. The inventors found that the ink droplets had a uniform shape and a uniform distribution. This is discussed further below with respect to examples 23, 25 and 26.
The examples demonstrate that different combinations of polymer dispersions and substrates result in different image durability. Examples 1-3 show that the combination of vinyl chloride copolymer dispersion with brown paperboard produces images with very good durability. In contrast, examples 4-6 show that the combination of vinyl chloride copolymer dispersions with glass substrates produces images with poor durability. Examples 7-10 demonstrate the good durability of the combination of vinyl chloride copolymer dispersions with aluminum substrates. Examples 11-14 demonstrate that the durability of the combination of vinyl chloride copolymer dispersions with PVC substrates is still reasonably good.
Example 17 shows that the optimum durability results for alkyd resin dispersions comprising fluorocarbon surfactants are with aluminum substrates, while good results are obtained with wood substrates (example 16) and still better results are obtained with PVC substrates (example 15).
Comparison of example 18 with examples 19-22 shows that image durability can be improved by incorporating an acetylenic diol surfactant into the alkyd dispersion. Comparison of examples 24 and 25 with example 23 shows that image durability can be improved by incorporating ground calcium carbonate into the alkyd resin dispersion.
Comparative example 1
The method of the above example is repeated except as follows: instead of an aqueous alkyd dispersion, a plastisol dispersion (dispersion of polyvinyl chloride polymer in an ester-based plasticizer) similar to the dispersion used in WO2018/110518 was used.
Photomicrograph images
A micrograph of the image produced in example 23 is shown in figure 2 a. The ink droplets showed a uniform distribution. A micrograph of the image produced in example 26 is shown in figure 2 b. A micrograph of the image produced in example 25 is shown in figure 2 c.
A micrograph of the image produced in comparative example 1 is shown in figure 3. The ink droplets show an uneven distribution which will result in poor color intensity and therefore require more ink to be used.
Examples 27 to 34
Aqueous polymer dispersions were prepared as outlined in tables 2A and 2B below. The alkyd resin dispersion was Vilaqua from Vil Resins ltdTM615a 55. Vinyl chloride copolymer dispersion is Vinnol from Wacker Chemie AGTMCE 35. The vinyl acetate homopolymer dispersion is Emultex from SynthomerTM581. The wetting agent is Surfynol from EvonikTM440. Diisocyanate formulations 1, 2 and 3 were DesmodurTM DN、DesmodurTM2860 and BayhydurTM3100, all from Covestro.
[ Table 2A ]
Example 27
Example 28
Example 29
Example 30
Alkyd resin Dispersion (g)
40
30
30
Vinyl chloride copolymer Dispersion (g)
10
10
Vinyl acetate homopolymer dispersion (g)
40
10
10
10
Wetting agent (g)
0.4
0.4
0.4
0.4
Diisocyanate preparation 1(g)
10
Viscosity (mPas)
100,000
100,000
16,200
7,800
% solids
32.4
43.6
37.8
37.8
[ Table 2B ]
Example 31
Example 32
Example 33
Example 34
Alkyd resin Dispersion (g)
30
30
30
30
Vinyl chloride copolymer Dispersion (g)
5
5
5
10
Vinyl acetate homopolymer dispersion (g)
10
10
10
10
Wetting agent (g)
0.4
0.4
0.4
0.4
Diisocyanate preparation 1(g)
10
Diisocyanate preparation 2(g)
10
Diisocyanate preparation 3(g)
10
Water (W)
15
Viscosity (mPas)
27,000
26,880
49,206
66
% solids
50
28
36.8
34.1
Each aqueous polymer dispersion was applied to a PVC substrate. The ink is printed onto the liquid polymer layer. The printed layer was dried at 130 ℃. The printing results are shown in table 3:
[ Table 3]
This application is based on and claims priority from uk patent application No.1814668.8 filed on 2018, 9, 10, the entire content of which is hereby incorporated by reference.
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