WO2020018360A1 - Food-contact, matte, soft-touch films - Google Patents

Abstract

Disclosed are compositions and methods for soft-touch films. In one example embodiment, the soft-touch film includes a base film, such as a biaxially oriented polypropylene film having one or multiple layers. The base film is coated by a matte coating on a first side of the base film, wherein the matte coating includes styrene block copolymers or a water-based polyurethane dispersion, wherein the matte coating, when dried, feels like peach skin or has a velvety texture and has a gloss of less than 20% at 85° under ASTM D2457.

Description

FOOD-CONTACT, MATTE, SOFT-TOUCH FILMS

REFERENCE TO RELATED APPLICATIONS

[0001] This application is a Patent Cooperation Treaty application, which claims priority to United States provisional patent application serial number 62/699,813 filed on 18 July 2018 that is hereby incorporated by this reference in its entirety.

FIELD

[0002] The disclosure generally relates to compositions, structures, methods for soft-touch, matte films, and, furthermore, those that are food-contact safe in the meaning of European Regulations No 1935/2004.

BACKGROUND

[0003] Films for packaging and other applications are highly desirable in the marketplace. A purpose of this disclosure is to provide films that have a desired aesthetic of a matte, soft-touch while at the same time being food-contact safe and optionally include additionally desired functionalities, such as controlled coefficient of friction, sealability, barrier to water vapor, barrier to oxygen, printability, improved antistatic properties, and improved scratch-resistance.

SUMMARY

[0004] Disclosed are compositions and methods for soft-touch films. In one example embodiment, the soft-touch film includes a base film, such as a biaxially oriented polypropylene film having one or multiple layers. The base film is coated by a matte coating on a first side of the base film, wherein the matte coating includes styrene block copolymers or a water-based polyurethane dispersion, wherein the matte coating, when dried, feels like peach skin or has a velvety texture and has a gloss of less than 20% at 85° under ASTM D2457.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] So that the manner in which the above recited features, advantages and objects of this disclosure are attained and may be understood in detail, a more particular description, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings.

[0006] It is to be noted, however, that the appended drawings illustrate only typical embodiments of this disclosure and are therefore not to be considered limiting of its scope, for the disclosure may admit to other equally effective embodiments.

[0007] FIG. 1 provides a table, which details several examples of soft-touch, matte coatings on base films in accordance with the disclosed methods, structures, and compositions.

[0008] FIG. 2 shows the ratio of the dynamic coefficient of friction to the static coefficient of friction for each of a subset of designs from FIG. 1 in accordance with the disclosed methods, structures, and compositions.

[0009] FIG. 3 shows the water-vapor barrier efficacy for an example embodiment of a soft- touch, matte-coated, biaxially oriented polypropylenic (“BOPP”) base film in accordance with the disclosed methods, structures, and compositions.

[0010] FIG. 4 shows the sealability in g/25.4 mm over a temperature range from 70-l50°C for an example embodiment of a soft-touch, matte-coated, BOPP base film in accordance with the disclosed methods, structures, and compositions.

[0011] FIG. 5 is a tabular depiction of antistatic properties for two example embodiments of soft-touch, matte-coated, BOPP base film in accordance with the disclosed methods, structures, and compositions. DETAILED DESCRIPTION

[0012] Below, directional terms, such as“above,”“below,”“upper,”“lower,”“front,” “back,”“top,”“bottom,” etc., are used for convenience in referring to the accompanying drawings. In general,“above,”“upper,”“upward,”“top,” and similar terms refer to a direction away the earth’ s surface, and“below,”“lower,”“downward,”“bottom,” and similar terms refer to a direction toward the earth’ s surface, but is meant for illustrative purposes only, and the terms are not meant to limit the disclosure.

[0013] Various specific embodiments, versions and examples are described now, including exemplary embodiments and definitions that are adopted herein for purposes of understanding. While the following detailed description gives specific preferred embodiments, those skilled in the art will appreciate that these embodiments are exemplary only, and that the disclosure can be practiced in other ways. For purposes of determining infringement, the scope of the invention will refer to the any claims, including their equivalents, and elements or limitations that are equivalent to those that are recited.

[0014] As used herein,“polymer” may be used to refer to homopolymers, copolymers, interpolymers, terpolymers, etc. Likewise, a“copolymer” may refer to a polymer comprising two monomers or to a polymer comprising three or more monomers.

[0015] As used herein, “intermediate” is defined as the position of one layer of a multilayered film wherein said layer lies between two other identified layers. In some embodiments, the intermediate layer may be in direct contact with either or both of the two identified layers. In other embodiments, additional layers may also be present between the intermediate layer and either or both of the two identified layers.

[0016] As used herein,“elastomer” is defined as a propylene-based or ethylene-based copolymer that can be extended or stretched with force to at least 100% of its original length, and upon removal of the force, rapidly (e.g., within 5 seconds) returns to its original dimensions.

[0017] As used herein,“plastomer” is defined as a propylene-based or ethylene-based copolymer having a density in the range of 0.850 g/cm³ to 0.920 g/cm³ and a DSC melting point of at least 40 °C.

[0018] As used herein,“substantially free” is defined to mean that the referenced film layer is largely, but not wholly, absent a particular component. In some embodiments, small amounts of the component may be present within the referenced layer as a result of standard manufacturing methods, including recycling of film scraps and edge trim during processing.

[0019] By“consist essentially of,” what is meant, for example, is that a particular film layer does not have any more than 1 wt % or 2 wt % or 3 wt % or 4 wt % or 5 wt % of other polymers in the bulk material constituting the film layer’ s composition, but“consist essentially of’ does not exclude the possibility that the particular film layer also has additives, such as anti-slip agents, anti-blocking agents, anti-oxidants, pigments, whitening agents, cavitation agents, etc. regardless of what polymers or other materials make up the additive(s).

[0020] As used herein,“about” means the number itself and/or within 5% of the stated number. For instance, with about 5%, this means 5 and/or any number or range within the range of 4.75 to 5.25, e.g., 4.75 to 4.96, 4.81 to 5.1, etc.

[0021] Disclosed are compositions, structures and methods for food-contact safe, matte, soft-touch (/._<?.,“peach skin” or velvety texture) films having one or more functionalities that include for example, but without limitation, controlled coefficient of friction, sealability, barrier to water vapor, barrier to oxygen, printability, improved antistatic properties, and improved scratch-resistance. To achieve these compositions, structures and methods, the approach is to use chemicals such as synthetic rubber, water-based dispersions, polyurethane (“PU”) dispersions, and silicone-based additives as a food-contact alternative to non-food- contact polyurethane -based materials. Of these, the synthetic rubber dispersions may be enabled by Dow^® BLUEWAVE^® technology or otherwise.

[0022] More specifically, disclosed are compositions, structures and methods food-contact safe, matte, soft-touch films that permit their use in standard applications, such as cardboard lamination, but also in flexible packaging applications for foods or labels. To that end, there is at least a base film with a coating. The base film, for example, may comprise, consists essentially or, or consists of one or more optionally oriented polyolefin or polyester films, such as biaxially oriented polypropylene (“BOPP”), biaxially oriented biaxially oriented polyethylene terephthalate (“BOPET”), polyethylene (“PE”), biaxially oriented polyethylene (“BOPE”), oriented polyamide“(OPA”), polylactide/polyhydroxyalkanoates (“PLA/PHA”), combinations thereof, and so forth. Each of such example base films may include layers known as cores, ties, skins, and/or sealants, and each such layer may be clear, white, colored, treated and/or metallized. The base film may be coated on a first side, a second side, or both sides. The coating material (“coating”) may include one or more layers of styrenic block copolymers, e.g., poly(styrene -butadiene-styrene) (“SBS”), poly(styrene-isoprene-styrene) (“SIS”), and poly(styrene-ethylene/butylene-styrene) (“SEBS”), polyurethane -based polymers, other thermoplastic elastomers and functionalized grades, silicone-based additives, combinations thereof, and so forth in order to provide the base film with a matte, soft-touch and eliminate the plastic visual-aspect of the film. Additionally, additives included in the coated base film may impart additional functionalities, such as the ones previously mentioned, /._<?., controlled coefficient of friction, sealability, barrier to water vapor, barrier to oxygen, printability, improved antistatic properties (/._<?., smoother sheet-to-sheet processing), and improved scratch- resistance.

[0023] In various embodiments, disclosed are multilayered films, typically one or more base films comprising a core layer, optionally one or more tie layers intermediate on one or both sides of the core, and optionally having polymer coating(s), whether with or without primer(s).

[0024] A matte coating may be applied to either or both sides, optionally primed, of the base film. Examples of primers include PU, aziridine-based primers, ethylene acrylic acid copolymer (“EAA”), and combinations thereof, wherein the dry coating weight of the primer(s) may be within a range from 0.05 to 1.0 g/m² for some example embodiments, but in other example embodiments, the coating weight may be outside of this range.

[0025] The matte coating(s) on either or both sides of the optionally primed base film may include one or more layers of styrenic block copolymers, e.g., SBS, SIS, and SEBS, polyurethane -based polymers, other thermoplastic elastomers and functionalized grades, silicone-based additives, combinations thereof, and so forth. The dry coating weight of such coating(s) may be within a range from 0.5 to 20.0 g/m² for some example embodiments, but in other example embodiments, the coating weight may be outside of this range.

[0026] One side of the optionally primed base film may include non-matte coating(s). The primer(s), if used, may be the same as those examples previously mentioned or others and fall within or outside the dry coating weight range from 0.05 to 1.0 g/m². The non- matte coating(s) may include water-based dispersion(s), such as very low temperature sealing coating(s) (e.g., EAA-based VLT sealing coatings), polymers of acrylic, polyvinylidene chloride (“PVdC”), ethylene-vinyl acetate (“EVA”), other printable coatings that may be used, for example, in conjunction with traditional, UV, and digital printing technologies, combinations thereof, and so forth. In other example embodiments, the non-matte coating(s) may be solvent-based. Again, exemplary dry coating weights of such coating(s) may be within a range from 0.5 to 20.0 g/m² for some example embodiments, but in other example embodiments, the coating weight may be outside of this range. [0027] A“soft-touch” to matte-coated, optionally primed base films is achieved through adding additives. Additives may be present in the base film, primer, and/or the coating (/._<?., matte, non-matte, or both) layers. Additives may include, but are not limited to opacifying agents, pigments, colorants, cavitating agents, slip agents, antioxidants, anti-fog agents, anti static agents, anti-block agents, fillers, moisture barrier additives, gas barrier additives, gas scavengers, and combinations thereof. Such additives may be used in effective amounts, which vary depending upon the property required.

[0028] For instance, additives may be added to control parameters, such as coefficient of friction and scratch-resistance. The chemicals that may be added to the primer(s), coating(s) or both to produce a soft-touch material include, for example: (1) particles, such as silica, talc, polymethyl methacrylate (“PPMA”), silicone, others, and combinations thereof; (2) wax(es), such as camauba, PE, others, and combinations thereof; (3) antistatic additives; and (4) clays for gloss and roughness adjustment. In order to bring more functionality, e.g., printability, aroma barrier, sealability, water-vapor barrier, oxygen barrier, etc., raw materials such as acrylic(s), low temperature sealing coatings, PVDC, or others may be blended with the soft- touch coating.

[0029] Other additives may include suitable opacifying agents, pigments or colorants, such as iron oxide, carbon black, aluminum, titanium dioxide (TiCk), calcium carbonate (CaCOs), and combinations thereof.

[0030] Cavitating or void- initiating additives may include any suitable organic or inorganic material that is incompatible with the polymer material(s) of the layer(s) to which it is added, at the temperature of biaxial orientation, in order to create an opaque film. Examples of suitable void-initiating particles are PBT, nylon, solid or hollow pre-formed glass spheres, metal beads or spheres, ceramic spheres, calcium carbonate, talc, chalk, or combinations thereof. The average diameter of the void- initiating particles typically may be from about 0.1 to 10 pm. [0031] Slip agents may include higher aliphatic acid amides, higher aliphatic acid esters, waxes, silicone oils, and metal soaps. Such slip agents may be used in amounts ranging from 0.1 wt % to 2 wt % based on the total weight of the layer to which it is added. An example of a slip additive that may be useful is erucamide.

[0032] Non-migratory slip agents, used in one or more skin layers of the multilayered films, may include polymethyl methacrylate (PMMA). The non-migratory slip agent may have a mean particle size in the range of from about 0.5 pm to 8 pm, or 1 pm to 5 pm, or 2 pm to 4 pm, depending upon layer thickness and desired slip properties. Alternatively, the size of the particles in the non-migratory slip agent, such as PMMA, may be greater than 20% of the thickness of the skin layer containing the slip agent, or greater than 40% of the thickness of the skin layer, or greater than 50% of the thickness of the skin layer. The size of the particles of such non-migratory slip agent may also be at least 10% greater than the thickness of the skin layer, or at least 20% greater than the thickness of the skin layer, or at least 40% greater than the thickness of the skin layer. Generally spherical, particulate non-migratory slip agents are contemplated, including PMMA resins, such as EPOSTAR™ (commercially available from Nippon Shokubai Co., Ltd. of Japan). Other commercial sources of suitable materials are also known to exist. Non-migratory means that these particulates do not generally change location throughout the layers of the film in the manner of the migratory slip agents. A conventional poly dialkyl siloxane, such as silicone oil or gum additive having a viscosity of 10,000 to 2,000,000 centistokes is also contemplated.

[0033] Suitable anti-oxidants may include phenolic anti-oxidants, such as IRGANOX® 1010 (commercially available from Ciba-Geigy Company of Switzerland). Such an anti oxidant is generally used in amounts ranging from 0.1 wt % to 2 wt %, based on the total weight of the layer(s) to which it is added. [0034] Anti-static agents may include alkali metal sulfonates, polyether-modified polydiorganosiloxanes, polyalkylphenylsiloxanes, and tertiary amines. Such anti-static agents may be used in amounts ranging from about 0.05 wt % to 3 wt %, based upon the total weight of the layer(s).

[0035] Examples of suitable anti-blocking agents may include silica-based products such as SYLOBLOC^® 44 (commercially available from Grace Davison Products of Colombia, Md.), PMMA particles such as EPOSTAR™ (commercially available from Nippon Shokubai Co., Ltd. of Japan), or polysiloxanes such as TOSPEARL™ (commercially available from GE Bayer Silicones of Wilton, Conn.). Such an anti -blocking agent comprises an effective amount up to about 3000 ppm of the weight of the layer(s) to which it is added.

[0036] Useful fillers may include finely divided inorganic solid materials such as silica, fumed silica, diatomaceous earth, calcium carbonate, calcium silicate, aluminum silicate, kaolin, talc, bentonite, clay and pulp.

[0037] Suitable moisture and gas barrier additives may include effective amounts of low- molecular weight resins, hydrocarbon resins, particularly petroleum resins, styrene resins, cyclopentadiene resins, and terpene resins.

[0038] Optionally, one or more layers may be compounded with a wax or coated with a wax-containing coating, for lubricity, in amounts ranging from 2 wt % to 15 wt % based on the total weight of the skin layer. Any conventional wax, such as, but not limited to Carnauba™ wax (commercially available from Michelman Corporation of Cincinnati, Ohio) that is useful in the contemplated films.

[0039] Cross-linkers may improve properties, e.g., water/solvent resistance, of the soft- touch, matte coated base films. Example cross-linkers, among others, may include polyarziridines, and isocyanates. [0040] With regard to printability, gravure is ideally suited for ink adhesion when using either synthetic rubber-base coatings or PU-based coatings in soft-touch, matte coated base films. UV-ink printability is possible for synthetic rubber-base coatings with the addition of adhesion promoter(s). Some specific UV-printable, water-based coatings, with or without adhesion promoters, may be added to the waterborne PU dispersion based on aliphatic isocyanates and polyether diols to improve printability with UV inks. Traditional UV inks technologies including UV flexography, UV offset, and so forth.

[0041] Turning now to Figure 1, disclosed is a table that details several examples of soft- touch, matte coatings on biaxially oriented polypropylene (“BOPP”) base films. Gloss measurements at 20°, 45°, 60° and 85° are reported in percentages for some example embodiments, wherein the measurements were obtained using a glossmeter and the ASTM D2457 standard. As shown in Figure 1, the soft-touch, matte films have a tri-gloss, /._<?., at 85°, in the general range of 12% to 19.8%. Notable commentary includes that the white-opaque BOPP films with soft-touch, matte coatings provided a paper-like appearance. Metallized BOPP and BOPET films with soft-touch, matte coatings provided an aluminum-foil-like appearance. Figure 1 also shows that some of the base films may have non-matte coatings on the other side of the base film from where the matte coating is. Whether shown in Figure 1 or not, it is noted that said other side of the base film may include a non-matte coating or matte coating, regardless of the matte coating that is on the one side of the base film.

[0042] Moving on, Figure 2 shows the ratio of the dynamic coefficient of friction to the static coefficient of friction for each of a subset of designs from Figure 1. Measurements were made on a rub tester using the ASTM D1894 standard at a temperature of 23 °C.

[0043] Figure 3 shows the water- vapor barrier efficacy for an example embodiment of a soft-touch, matte coated BOPP base film. Measurements were obtained using the ASTM F1249 standard at a temperature of 38°C and 90% relative humidity. [0044] Figure 4 shows the sealability in g/25.4 mm over a temperature range from 70- l50°C for an example embodiment of a soft-touch, matte coated BOPP base film. The example embodiment exhibited remarkable sealability at l30°C and greater temperatures. Measurements were obtained using the ASTM F2824 standard.

[0045] Finally, Figure 5 is a tabular depiction of antistatic properties for two example embodiments of soft- touch, matte coated BOPP base film. Measurements were obtained using an internal device that measured the static electricity and the static decay with time after surface friction/rubbing with 15 cycles (Internal standard# LMS-A11 4.10 TEC 3030).

[0046] In view of the foregoing, soft-touch, matte films could be used in innumerable applications, which include, for example, flexible, food and non-food bags, packages, pouches (e.g., stand-up, vertical fill-and-seal, horizontal fill-and-seal, etc.), films, laminates, labels, and other structures may be formed from the above-described films, wherein such may hold or retain products (e.g., food, beverages) of any phase.

[0047] Below are example embodiments of the disclosed invention that are written in claim format:

1. A soft-touch film comprising:

a base film; and a matte coating on a first side of the base film, wherein the matte coating comprises styrene block copolymers or a water-based polyurethane dispersion, wherein the matte coating, when dried, feels like peach skin and has a gloss of less than 20% at 85° under ASTM D2457.

2. The soft- touch film of claim 1, wherein the matte coating comprising the water-based polyurethane dispersion further comprises isocyanates. 3. The soft- touch film of claim 1, wherein the matte coating comprising the water-based polyurethane dispersion further comprises diols.

4. The soft-touch film of claim 1, further comprising a primer between the base film and the matte coating.

5. The soft-touch film of claim 4, wherein polymers in the primer are polyurethane-based.

6. The soft-touch film of claim 4, wherein polymers in the primer are aziridine -based.

7. The soft-touch film of claim 4, wherein polymers in the primer are ethylene-acrylic-acid- based.

8. The soft-touch film of claim 1, further comprising one or more additives in the matte coating.

9. The soft- touch film of claim 1, further comprising silicone-based additives in the matte coating.

10. The soft-touch film of claim 1, wherein the matte coating further comprises one or more thermoplastic elastomers.

11. The soft- touch film of claim 1, further comprising a non-matte coating on a side of the base film that is opposite of the first side.

12. The soft-touch film of claim 11, wherein the non-matte coating comprises acrylic or polyvinyldichloridic polymers.

13. The soft-touch film of claim 11, wherein the non- matte coating is a sealing coating.

14. The soft-touch film of claim 1, wherein the non-matte coating comprises a water-based dispersion.

15. The soft-touch film of claim 1, wherein the non-matte coating is solvent-based.

16. The soft-touch film of claim 1, wherein the soft-touch film is food-contact safe.

17. The soft-touch film of claim 1, wherein the soft-touch film is flexible. 18. The soft- touch film of claim 1, wherein the soft-touch film is laminated to a substrate, e.g., wood, paper, cardboard, glass, another film, etc.

19. The soft-touch film of claim 1, wherein a ratio of dynamic coefficient of friction to static coefficient of friction for the matte coating comprising the styrene block copolymers is less than 0.5 at 23 °C under ASTM D1894.

20. The soft-touch film of claim 1 having a seal strength of at least 220 g/25.4mm at H0°C under ASTM F2824.

[0048] While the foregoing is directed to example embodiments of the disclosed invention, other and further embodiments may be devised without departing from the basic scope thereof, wherein the scope of the disclosed apparatuses, systems and methods are determined by one or more claims.

Claims

CLAIMS What is claimed is:

1. A soft-touch film comprising:

a base film; and

a matte coating on a first side of the base film, wherein the matte coating comprises styrene block copolymers or a water-based polyurethane dispersion,

wherein the matte coating, when dried, feels like peach skin and has a gloss of less than 20% at 85° under ASTM D2457.

2. The soft-touch film of claim 1, wherein the matte coating comprising the water-based polyurethane dispersion further comprises isocyanates.

3. The soft- touch film of claim 1, wherein the matte coating comprising the water-based polyurethane dispersion further comprises diols.

4. The soft-touch film of claim 1, further comprising a primer between the base film and the matte coating.

5. The soft-touch film of claim 4, wherein polymers in the primer are polyurethane-based.

6. The soft-touch film of claim 4, wherein polymers in the primer are aziridine -based.

7. The soft-touch film of claim 4, wherein polymers in the primer are ethylene-acrylic-acid- based.

8. The soft-touch film of claim 1, further comprising one or more additives in the matte coating.

9. The soft- touch film of claim 1, further comprising silicone-based additives in the matte coating.

10. The soft-touch film of claim 1, wherein the matte coating further comprises one or more thermoplastic elastomers.

11. The soft- touch film of claim 1, further comprising a non-matte coating on a side of the base film that is opposite of the first side.

12. The soft-touch film of claim 11, wherein the non-matte coating comprises acrylic or polyvinyldichloridic polymers.

13. The soft-touch film of claim 11, wherein the non- matte coating is a sealing coating.

14. The soft-touch film of claim 1, wherein the non-matte coating comprises a water-based dispersion.

15. The soft-touch film of claim 1, wherein the non-matte coating is solvent-based.

16. The soft-touch film of claim 1, wherein the soft-touch film is food-contact safe.

17. The soft-touch film of claim 1, wherein the soft-touch film is flexible.

18. The soft-touch film of claim 1, wherein the soft-touch film is laminated to a substrate.

19. The soft-touch film of claim 1, wherein a ratio of dynamic coefficient of friction to static coefficient of friction for the matte coating comprising the styrene block copolymers is less than 0.5 at 23 °C under ASTM D1894.

20. The soft-touch film of claim 1 having a seal strength of at least 220 g/25.4mm at 110°C under ASTM F2824.