HK1068908A - Synthetic paper skins and methods of their manufacture - Google Patents

Description

Synthetic paper skins and methods for their manufacture

Technical Field

The present invention relates to a skin layer for synthetic paper. The skin layer may be part of a multi-layer article used as a synthetic paper or synthetic label. The skin layer has low gloss, good opacity and is printable by thermal transfer.

Background

Synthetic paper is known and can be utilized as an alternative to natural paper. Synthetic paper has desirable properties that natural paper does not provide. Synthetic paper has been used in many fields to replace natural paper. However, one annoying aspect is the ink adhesion of synthetic paper. The ink can be easily removed, especially thermally transferred. Coatings are often added to synthetic papers to improve their ink adhesion.

Synthetic paper can be used as a label by applying an adhesive or heat-seal layer to the synthetic paper. When used as a goods (goods) label, the synthetic paper with the bar code must be optically readable. When the synthetic paper gloss is too high, reading is difficult or impossible. The merchandise tag is often attached to the previous tag. When the price of a product changes, it is common to label the product over the previous label. The tag must be opaque so that no read errors are caused by the information on the embedded tag.

Labels are often printed by thermal transfer printing. The thermal transfer method uses a heated stylus (stylus) that heats wax-like ink on a transfer belt. The heated ink melts and is transferred to the label. When the ink was applied to the synthetic label, the ink did not adhere sufficiently. In fact, the print had a good appearance (easy to read and with a clear image). However, when the ink is subjected to abrasion (e.g., with a fingernail), the ink is smeared or actually removed.

WO 99/58336 published in the name of glapak Inc relates to paper-like sheets of plastic. The paper-like sheet material resembles paper to the touch and has at least some paper properties.

U.S. patent 4,986,866, issued in the name of Ohba et al, relates to a method of producing synthetic label paper. The label can be used for in-mold decoration of containers.

U.S. patent 5,616,384 issued to Goettmann et al relates to recyclable polymeric label paper. These materials can be used in the blow molded container mold without the use of adhesive materials.

U.S. patent 5,667,872 issued to Ohno et al relates to synthetic paper having a multi-layer structure and excellent printing characteristics.

There is a need for synthetic paper for use in thermal transfer printing processes. The printing must be durable and not easily removed by abrasion.

Summary of the invention

The present invention relates to a polymer film useful as a skin layer of synthetic paper or labels comprising (A) a filler, (B) a carrier polymer and (C) a small amount of an ink adhesion improving polymer. The film may be printed by thermal transfer printing. The present invention relates to a multi-layer article for use as a synthetic paper or label.

Detailed Description

As noted above, the present invention relates to a skin layer and a multi-layer article useful as a synthetic paper or label. These materials can be printed, in particular by thermal transfer. The print is durable and abrasion resistant. The skin layers and the multilayer articles made therefrom have a 60 ° gloss of less than about 40, or less than about 30, or less than about 25. In one embodiment, the skin layer and the multilayer article have a 60 ° gloss of less than about 20, or even less than 18. When synthetic paper is used as a shelf label and read with an electronic reader, the gloss of the label causes erroneous reading or no reading due to light reflection on the surface of the synthetic paper or the label. In one embodiment, the skin layer is free of a coating that improves ink adhesion.

In another embodiment, the skin layer and the multilayer article made therefrom have good opacity. The opacity of the skin layer and the multilayer article avoids and reduces false readings or non-readings caused by materials beneath the multilayer article. This situation typically occurs when the tags are attached to each other with information on the underlying tags, such as bar code data, interfering with the scanner reading the uppermost tag. The multilayer articles of the present invention have a light transmission of greater than 75%, or greater than 80%, or greater than 85% or greater than 90%. The skin layer has a matte finish.

Cortex layer

The skin layer comprises (A) a filler, (B) a carrier polymer and (C) a small amount of an ink adhesion improving polymer. The skin layer typically comprises from about 3% to about 25%, or from about 5% to about 20%, or from about 8% to about 15% of the multilayer article.

Filler material

The skin layer contains a filler. The filler is generally present in an amount of less than 65 wt%. In one embodiment, the filler is present in an amount of about 5 to about 50 wt%, or about 8 to about 45 wt%, or about 10 to about 40 wt%. Here and elsewhere in the specification and claims, range and ratio limits are combinable. Mixtures of fillers may be used. When mixtures of fillers are used, the combined amounts are reflected in the above percentages.

Fillers include calcium carbonate, titanium dioxide, clay, diatomaceous earth, talc, mica, barium sulfate, aluminum sulfate, silica, or mixtures of two or more thereof. Specific examples of the amount of each filler are given below. The amount is in parts by weight.

Filler material Measurement of

About 5 to about 50, or about 10 to about 40, or about 15 to about 30, titanium dioxide

About 5 to about 50, or about 10 to about 40, or about 15 to about 30 of talc

Mica of about 5 to 50, or about 10 to 40, or about 15 to 30

Calcium carbonate of about 5 to 65, or about 10 to 55, or about 15 to 40

In another embodiment, useful filler mixtures include antiblocking agents (selected according to the conditions prevailing in the extruder), silica, talc, diatomaceous earth, and any mixtures thereof. The finely divided substantially water-insoluble filler particles may be finely divided substantially water-insoluble inorganic filler particles.

The finely divided substantially water-insoluble inorganic filler particles comprise particles of metal oxides. The metal oxide constituting the particles may be a simple metal oxide (i.e., an oxide of a single metal), or it may be a composite metal oxide (i.e., an oxide of two or more metals). The particles of metal oxide may be particles of a single metal oxide, or they may be a mixture of different particles of different metal oxides.

Examples of suitable metal oxides include alumina, silica, and titania. Other oxides may optionally be present in minor amounts. Examples of such optional oxides include, but are not limited to, zirconia, hafnia, and yttria. Other metal oxides which may optionally be present are those which are normally present as impurities, for example iron oxide. For purposes of this specification and claims, silicon is considered to be a metal.

When the particles are particles of alumina, the alumina is most often aluminum hydroxide (alumina). Particles of aluminum hydroxide, AlO (OH), and their preparation are known. The preparation and properties of aluminum hydroxide are described by B.E. yolk in The American ceramic Society Bulletin, Vol.54, No.3, (3/1975), p.289-. Briefly, aluminum isopropoxide or aluminum sec-butoxide is hydrolyzed in excess water under vigorous agitation at 75 ℃ to 80 ℃ to form a slurry of aluminum hydroxide. The aluminum hydroxide is then peptized with an acid at a temperature of at least 80 ℃ to form a transparent aluminum hydroxide sol which exhibits a Tyndall effect when irradiated with a narrow beam of light. Since the alumina monohydrate of the sol is neither white nor colored, it is not a pigment and does not function as a pigment in the present invention. The acid used is not complexed with aluminum and it is of sufficient strength to produce the desired charge effect at low concentrations. Nitric acid, hydrochloric acid, perchloric acid, acetic acid, chloroacetic acid and formic acid meet these requirements. The acid concentration is generally in the range of from 0.03 to 0.1mol of acid per mol of aluminium alkoxide. While not wishing to be bound by any theory, it is believed that the aluminum monohydroxide produced in this manner is pseudo-boehmite. Pseudoboehmite is actually the preferred aluminum monohydroxide for use in the present invention. The aluminum hydroxide is not a pigment and does not function as a pigment in the present invention. In most cases, the aluminum monohydroxide is transparent and colorless.

Colloidal silica is also known. Its preparation and properties are described by R.K. Iler in The Chemistry of Silica, John Wiley & Sons, Inc., New York (1979) ISBN0-471-02404-X, 312-337 and U.S. Pat. No. 2,601,235; 2,614,993, respectively; 2,614,994, respectively; 2,617,995, respectively; 2,631,134, respectively; 2,885,366; and 2,951,044, the disclosures of which are incorporated herein by reference in their entirety. Examples of commercially available colloidal silicas include Ludox  HS, LS, SM, TM and CL-X colloidal silicas (E.I. Du Pont de Nemours & Company, Inc.) in which the counterion is sodium, and Ludox  AS colloidal silicas (E.I. Du Pont de Nemours & Company, Inc.) in which the counterion is ammonium. Another example is Ludox  AM colloidal silica (e.i. du Pont de nemours & Company, Inc.) in which some of the silicon atoms have been replaced with aluminum atoms and the counterion is sodium.

Colloidal titanium dioxide is also known. Its preparation and properties are described in U.S. patent No.4,275,118. Colloidal titanium dioxide can also be prepared by reacting titanium isopropoxide [ CAS 546-68-9] with water and tetramethylammonium hydroxide.

The filler particles typically have a largest dimension of less than 500 nanometers. The filler particles often have a largest dimension of less than 100 nanometers. Typically, the largest dimension is less than 50 nanometers, or less than 20 nanometers.

Carrier resin

The skin layer has a carrier resin. The resin typically comprises from about 8 to about 65 wt%, or from about 10 to about 50 wt%, or from about 15 to about 45 wt% of the skin layer. The carrier resin includes polyolefins, thermoplastic polymers of ethylene and propylene, polyesters, polycarbonates, styrene derived polymers, polyurethanes, polyacryls, polymethacryloyl, polyvinyl alcohol, polyamides, polyimides, polysulfones, polymethylpentene, polyacetals, vinyl halide derived polymers, poly (ethylene-vinyl alcohol), vinyl acetate derived polymers, ionomers, and mixtures thereof.

In one embodiment, the support resin is a polyolefin. Polyolefins that can be utilized as the carrier resin include polymers and copolymers of ethylene, propylene, 1-butene, hexene, octene, and the like, or blends of mixtures of these polymers and copolymers. In one embodiment, the polyolefin comprises polymers and copolymers of ethylene and propylene. In another embodiment, the polyolefin includes propylene homopolymers, as well as copolymers such as propylene-ethylene copolymers and propylene-1-butene copolymers. Blends of polypropylene and polyethylene with each other, or blends of one or both of them with polypropylene-polyethylene copolymers are also useful. In another embodiment, the polyolefin film materials are those having a very high propylene content, i.e., polypropylene homopolymers, or propylene-ethylene copolymers, or blends of polypropylene and polyethylene having a low ethylene content, or propylene-1-butene copolymers, or blends of polypropylene and poly-1-butene having a low butene content.

Various polyethylenes can be used as the first polymeric material, including low, medium, and high density polyethylenes. An example of a useful Low Density Polyethylene (LDPE) is Rexene 1017 available from Huntsman.

Propylene homopolymers that can be used as the first polymeric material in the structures of the present invention, alone or in combination with the propylene copolymers described herein, include propylene homopolymers such as those having a Melt Flow Rate (MFR) of from about 0.5 to about 20 as determined by ASTM Test D1238, condition L. Many useful propylene homopolymers are commercially available from a variety of sources, some useful polymers include: 5A97, available from Union Carbide, having a melt flow rate of 3.9g/10min and a melt flow rate of 0.90g/cm³Density of (2)(ii) a DX5E66, also available from Union Carbide, having an MFI of 8.8g/10min and 0.90g/cm³(ii) a density of (d); and has an MFI of 3.9g/10min and a density of 0.90g/cm³Is available from wRD5-1057 of Union Carbide. Useful commercially available propylene homopolymers are also available from Ato Fina and Montel.

A wide variety of propylene copolymers are available and useful in the present invention. Propylene copolymers generally include copolymers of propylene and up to 10 wt% or even 20 wt% of at least one other alpha-olefin such as ethylene, 1-butene, 1-pentene, and the like. In one embodiment, the propylene copolymer is a propylene-ethylene copolymer having an ethylene content of about 0.2 wt% to about 10 wt%. These copolymers are prepared by techniques well known to those skilled in the art and are commercially available, for example, from Union Carbide. Propylene-ethylene copolymers containing about 3.2 wt% ethylene are commercially available from Union Carbide under the name DS6D 20. Another Union Carbide propylene-ethylene copolymer is DS6D81, which contains 5.5 wt% ethylene.

In another embodiment, the carrier resin comprises at least one thermoplastic copolymer or terpolymer derived from ethylene or propylene and a functionalized monomer selected from the group consisting of alkyl acrylates, acrylic acid, alkyl acrylic acid, and mixtures of two or more thereof. In one embodiment, the functionalized monomer is selected from the group consisting of alkyl acrylates, acrylic acid, alkyl acrylic acid, and mixtures of two or more thereof. In one embodiment, the first polymer is characterized by the absence of an ethylene vinyl acetate resin, and an acid or acid/acrylate modified ethylene vinyl acetate resin. The alkyl group of the alkyl acrylates and alkyl acrylic acids generally contains from 1 to about 8 carbon atoms, alternatively from 1 to about 2 carbon atoms. The functionalized monomer component of the copolymer or terpolymer is from about 1 to about 15 mole percent, and in one embodiment from about 1 to about 10 mole percent, of the copolymer or terpolymer molecule. Examples include: ethylene/methyl acrylate copolymers; ethylene/ethyl acrylate copolymers; ethylene/butyl acrylate copolymers, ethylene/methacrylic acid copolymers; ethylene/acrylic acid copolymers; anhydride modified low density polyethylene; anhydride-modified linear low density polyethylene, and mixtures of two or more thereof.

Ethylene-acid copolymers available from DuPont under the trade name Nucrel can also be used. They included Nucrel 0407, which had a methacrylic acid content of 4% by weight and a melting point of 109 ℃, and Nurel 0910, which had a methacrylic acid content of 8.7% by weight and a melting point of 100 ℃. Ethylene/acrylic acid copolymers available from Dow Chemical under the tradename Primacor are also useful. They include Primacor 1430, which has an acrylic monomer content of 9.5 wt%, a melting point of about 97 ℃ and a Tg of about-7.7 ℃. Ethylene/methyl acrylate copolymer available from Chevron under the trade name EMAC can be used. They included EMAC 2205 having a methyl acrylate content of 20 wt% and a melting point of 83 deg.C, and EMAC 2268 having a methyl acrylate content of 24 wt%, a melting point of about 74 deg.C and a Tg of about-40.6 deg.C.

In one embodiment, the carrier resin comprises at least one polyester. Polyesters are prepared from various diols (including ethylene glycol, propylene glycol, neopentyl glycol, etc.) or polyols (glycerol, trimethylolpropane, pentaerythritol, etc.) and one or more aliphatic or aromatic carboxylic acids. Polyethylene terephthalate (PET), PETG (PET modified with cyclohexanedimethanol), and polybutylene terephthalate (PBT) are useful and available from various commercial sources including Eastman. For example, Kodar 6763 is PETG available from Eastman Chemical. Another useful polyester available from duPont is SelarPT-8307, which is a polyethylene terephthalate. Another useful polyester is polyethylene naphthenate.

Particularly useful polyamide resins include those available under the general trade name Grivory from EMSAmerian Grilon Inc., Sumter, SC. such as CF6S, CR-9, XE3303, and G-21. Grivory G-21 is an amorphous nylon copolymer having a glass transition temperature of 125 ℃, a melt flow index (DIN 53735) of 90ml/10min, and an elongation at break (ASTM D638) of 15. Grivory CF65 is a nylon 6/12 film grade resin with a melting point of 135 ℃, a melt flow index of 50ml/10min, and an elongation at break of over 350%. Grilon CR9 is another nylon 6/12 film grade resin with a melting point of 200 ℃, a melt flow index of 200ml/10min, and an elongation at break of 250%. Grilon XE3303 is a nylon 6.6/6.10 film grade resin with a melting point of 200 ℃, a melt flow index of 60ml/10min, and an elongation at break of 100%. Other useful polyamide resins include, for example, those commercially available from Union Camp of Wayne, New Jersey under the Uni-Rez series, and dimer-type polyamide resins available from Bostik, Emery, Fuller, Henkel (under the Versamid series). Other suitable polyamides include those obtained by condensing dimerized vegetable acids with hexamethylene diamine. Examples of polyamides available from Union Camp include Uni-Rez 2665; Uni-Rez 2620; Uni-Rez 2623; and Uni-Rez 2695.

In one embodiment, the support resin comprises at least one polyimide. Examples of polyimide films include NOVAU polyimides available from Mitsubishi Chemical Industries Ltd of Tokyo, Japan and KAPTON polyimides available from Du Pont Electronics of Wilmington, Del.

In another embodiment, the support resin comprises at least one polystyrene. Polystyrene includes homopolymers as well as copolymers of styrene and substituted styrenes, such as alpha-methylstyrene. Examples of styrene copolymers and terpolymers include: acrylonitrile-butylene-styrene (ABS); styrene-acrylonitrile copolymer (SAN); styrene-butadiene (SB); styrene-maleic anhydride (SMA); and styrene-methyl methacrylate (SMMA) and the like. An example of a useful styrene copolymer is KR-10 available from Phillip Petroleum Co. KR-10 is believed to be a copolymer of styrene and 1, 3-butadiene.

In one embodiment, the carrier resin is at least one polyurethane. Polyurethanes include aliphatic and aromatic polyurethanes. The polyurethane is generally the following: (A) the reaction product of a polyisocyanate having at least two isocyanate (-NCO) functional groups per molecule with (B) at least one isocyanate-reactive group, such as a polyol or an amine having at least two hydroxyl groups. Suitable polyisocyanates include diisocyanate monomers and oligomers.

Useful polyurethanes include aromatic polyether polyurethanes, aliphatic polyether polyurethanes, aromatic polyester polyurethanes, aliphatic polyester polyurethanes, aromatic polycaprolactam polyurethanes, and aliphatic polycaprolactam polyurethanes. Particularly useful polyurethanes include aromatic polyether polyurethanes, aliphatic polyether polyurethanes, aromatic polyester polyurethanes, and aliphatic polyester polyurethanes.

Examples of commercially available polyurethanes include Sancure 2710  and/or Avalure UR 445  (which are equivalent copolymers of polypropylene glycol, isophorone diisocyanate and 2, 2-dimethylolpropionic acid, under the International Nomensuration Cosmetic Ingredient designation

"P PG-17/PPG-34/IPDI/DMPA Copolymerer"), Sancree 878 , Sancure 815 , Sancure 1301 , Sancure 2715 , Sancure 1828 , Sancure 2026 , Sancure 1818 , Sancure 853 , Sancure 830 , Sancure , Sancure 776 , Sancure 850 , Sancure 12140 , Sancure 12619 , Sancure 835 , Sancure 843 , Sancure 898 , Sancure 899 , Sancure 1511 , Sancure 1517, Sancure 1 20372, Sancure 5 , Sancure 2260 , Sancure 12412472, Sancure 23172, Bayer 23172, Gocure 23132, Gocure 23172, Gocure 2315, Gocure 23132, Bayer 23172, Bayer breech 3, Bayer breech 23132, Bayer breech 3, Bayer breech 23132, Bayer breech 23172, Bayer breech 3, Bayer breech 23132, Bayer breech 3, Bayer breech, witcobond W-242(Witco Performance Chemicals), Witcobond W-160(Witco Performance Chemicals), Witcobond W-612(Witco Performance Chemicals), Witcobond W-506(Witco Performance Chemicals), NeoRez R-600 (polytetramethylene ether urethane extended with isophorone diamine, available from Avecia, i.e., previous Avecia Resins), NeoRez R-940(Avecia Resins), NeoRez R-960(Avecia Resins), NeoRez R-962(Avecia Resins), NeoRez R-966(Avecia Resins), NeoRez R-967(Avecia Resins), NeoRezR-972(Avecia Resins), NeoRez R-9409(Avecia Resins), NeoRez R-9637(Avecia Resins), and Rez R-79 (Avecia Resins), Avecia Retz R-79 (Avecia Resins).

Particularly useful polyurethanes are aliphatic polyether polyurethanes. Examples of such aliphatic polyether polyurethanes include Sancure 2710  and/or Avalure UR 445 , Sancure 878 , NeoRezR-600, NeoRez R-966, NeoRez R-967, and Witcobond W-320.

In one embodiment, the carrier resin comprises at least one polyester polyurethane. Examples of such carrier resins include those sold by the company Sancor under the names "Sancure 2060" (polyester-polyurethane), "Sancure 2255" (polyester-polyurethane), "Sancure 815" (polyester-polyurethane), "Sancure 878" (polyether-polyurethane) and "Sancure 861" (polyether-polyurethane), by the company ICI under the names "Neorez R-974" (polyester-polyurethane), "Neorez R-981" (polyester-polyurethane) and "Neorez R-970" (polyether-polyurethane), and by the company Avecia under the name "Neocryl XK-90".

In another embodiment, the carrier resin is a polyacryl or polymethacryloyl resin. As used herein, "polyacryl" includes polyacrylates, polyacrylics, or polyacrylamides. These resins include those derived from acrylic acid, acrylates, acrylamides, methacrylic acid, methacrylates, and methacrylamides. Acrylates and methacrylates typically contain from 1 to about 30 carbon atoms in the pendant group, or from 1 to about 18 or 2 to about 12 carbon atoms in the pendant group.

Examples of commercial polyacryl and polymethacryl include Gelva  2497 (commercially available from Monsanto Co., St.Louis, Mo.), Duraplus  (commercially available from Rohm & Haas Co., Philadelphia, Pa.), Joncryl 5895 (commercially available from S.C.Johnson Polymer, Sturtevant, Wis.), SCX-1537(S.C.Johnson Polymer), SCX-1959(S.C.Johnson Polymer), SCX-1965(S.C.Johnson Polymer), Joncryl  530(S.C.Johnson Polymer), Joncryl  (S.C.Johnson Polymer), Joncryl LS 20 (commercially available from Allied Colloids, Suffolk, Glassol638), Glassol C37 (Allild C.537), Goldol Polyenriched (C.7619), Goodolls 367619 (Veodls), Goodls 3676, Goodrich 3, Goodrich 3676, Goodrich 3 (Veodls 3665), Goodrich 3676, Goodrich 3665, Goodrich 3 (BFohol III), wilmington, Mass), Neocryl  A-612(Avecia Resins), Neocryl  A-6044(Avecia Resins), Neocryl  A-622(Avecia Resins), Neocryl  A-623(Avecia Resins), Neocryl  A-634(Avecia Resins), and Neocryl  A-640(Avecia Resins).

Polycarbonates may also be used as the carrier resin. These polycarbonates are commercially available from Dow chemical Co. (Calibre) G.E. plastics (Lexan) and Bayer (Makrolon). Most commercial polycarbonates are obtained by the reaction of bisphenol a and phosgene in an interfacial process. Typical commercial polycarbonates have molecular weights of about 22,000 to about 35,000, and melt flow rates generally range from 4 to 22g/10 min.

In another embodiment, the support resin is a vinyl halide derived resin. They are generally vinyl halide chloride derived resins, sometimes referred to herein as PVC resins. These resins are well known, either as homopolymers of vinyl chloride or as copolymers of vinyl chloride with a minor amount of one or more ethylenically unsaturated comonomers copolymerizable with vinyl chloride. Examples of such ethylenically unsaturated comonomers include vinyl halides, such as vinyl fluoride and vinyl bromide; alpha-olefins such as ethylene, propylene and butylene; vinyl esters, such as vinyl acetate, vinyl propionate, vinyl butyrate, and vinyl hexanoate, their partially hydrolyzed products, such as vinyl alcohol; vinyl ethers such as methyl vinyl ether, propionic vinyl ether and butyl vinyl ether; acrylates, such as methyl acrylate, ethyl acrylate, methyl methacrylate and butyl methacrylate and other monomers, such as acrylonitrile, vinylidene chloride and dibutyl maleate. These resins are generally known and many are commercially available. Particularly useful polyvinyl chloride resins are homopolymers of vinyl chloride.

Examples of commercially available polyvinyl chloride resins include GEON 92, a medium to high molecular weight porous suspension PVC resin; GEON 128, a high molecular weight dispersion grade polyvinyl chloride resin; and GEON 11X 426FG, medium molecular weight PVC resin. GEON resins are available from Geon company. The number average molecular weight of the PVC resin useful in the present invention may range from about 20,000 to about 80,000, with a typical range being from about 40,000 to about 60,000.

In another embodiment, the polymeric core comprises at least one ionomer. Ionomers are polyolefins that contain ionically bonded molecular chains. Ionomer resins available from DuPont under the Surlyn trade name can also be used. They were identified as being obtained from sodium, lithium or zinc and a copolymer of ethylene and methacrylic acid. They include Surlyn 1601, i.e. a sodium-containing ionomer having a melting point of about 90 ℃ and a Tg of about-20.6 ℃, Surlyn 1650, i.e. a zinc-containing ionomer having a melting point of 97 ℃, Surlyn 1652, i.e. a zinc-containing ionomer having a melting point of 100 ℃, Surlyn1702, i.e. a zinc-containing ionomer having a melting point of 93 ℃, Surlyn 1705-1, i.e. a zinc-containing ionomer having a melting point of 95 ℃, Surlyn 1707, i.e. a sodium-containing ionomer having a melting point of 92 ℃, Syrlyn 1802, i.e. a sodium-containing ionomer having a melting point of 99 ℃, Surlyn 1855, i.e. a zinc-containing ionomer having a melting point of 88 ℃, Surlyn 1857, i.e. a zinc-containing ionomer having a melting point of 87 ℃, and Surlyn 1901, i.e. a sodium-containing ionomer having a melting point of 95 ℃.

Adhesion improving resin

The skin layer also includes an ink adhesion improving polymer. The polymer is typically a non-polar or low polar polymer. By polar polymer is meant a substantially hydrocarbon-like polymer containing a polar additive. Polar additives are those containing oxygen, sulfur, nitrogen, and the like. The polarity of the polymer is generally provided by copolymerizing a hydrocarbon monomer and a polar comonomer. The polar comonomer typically comprises less than about 35%, or less than 30%, or less than 25% of the molar amount of monomers used to prepare the ink adhesion promoting polymer. In another embodiment, the polar comonomer comprises less than 20%, or less than 15% of the molar amount of the ink adhesion promoting resin. In another embodiment, the ink adhesion promoting polymer is non-polar, i.e., hydrocarbon in nature.

The ink adhesion promoting polymer generally has a melting point of less than 170 ℃, or less than about 150 ℃, or less than 125 ℃, or less than 110 ℃, or less than about 95 ℃. The ink adhesion promoting polymer also generally provides a density of less than 0.97, or less than about 0.92, or less than about 0.89 g/cc.

The resin is generally present in an amount less than 50% by weight of the skin layer. The carrier resin is generally present in an amount of from about 5 to about 48%, or from about 8 to about 45%, or from 10 to about 40% by weight of the skin layer. The ink adhesion promoting polymer may include polyolefins, thermoplastic polymers of ethylene and propylene, polyurethanes, polyvinyl alcohols, vinyl acetate homopolymers, copolymers or terpolymers, ionomers, and mixtures thereof. These polymers have already been described above.

In one embodiment, the polymer is a polyolefin or a thermoplastic polymer of ethylene or propylene, or a mixture containing such polymers. In another embodiment, the polymer is polyethylene, polypropylene, a thermoplastic polymer of ethylene or propylene. Useful polyolefins include very low density polyethylene (ULDPE), known as ultra Low Density Polyethylene (LDPE), Linear Low Density Polyethylene (LLDPE), Low Density Polyethylene (LDPE), and the like. Very Low Density Polyethylene (VLDPE) has a density of about 0.890 to 0.912. An example of VLDPE is 88g of low density polyethylene (product of Union Polymer Corp., Low density polyethylene 339 (trade name)).

In one embodiment, the ink adhesion promoting polymer is an "ethylene/alpha-olefin copolymer". These polymers generally represent copolymers of ethylene with one or more comonomers, such as 1-butene, 1-pentene, 1-hexene, 1-octene, methylpentene and the like, in which the polymer molecule comprises long chains with relatively few side chain branches. These polymers are obtained by low pressure polymerization processes, the side branches present being short compared to non-linear polyethylenes (e.g. LDPE, low density polyethylene homopolymer). The ethylene/alpha-olefin copolymer generally has a density in the range of about 0.86g/cc to about 0.94 g/cc. The term Linear Low Density Polyethylene (LLDPE) is generally understood to include ethylene/alpha-olefin copolymers having a density in the range of about 0.915 to about 0.94 g/cc. Linear polyethylenes having densities in the range of about 0.926 to about 0.94g/cc are sometimes referred to as Linear Medium Density Polyethylenes (LMDPE). The low density ethylene/alpha-olefin copolymers may be referred to as very low density polyethylene (VLDPE, generally used to refer to ethylene/butene copolymers having a density of about 0.88 to about 0.91g/cc available from Union Carbide) and ultra low density polyethylene (ULDPE, generally used to refer to ethylene/octene copolymers supplied by Dow). Specific examples of commercially useful low density ethylene-1-octene copolymers include: dowlex 2036A having a density in the range of 0.9330 to 0.9370; dowlex 2032PER with density of 0.9240 to 0.9280; affinity PF 1140 having a density of 0.895 to 0.898; affinity VP 8770 with a density of 0.885; attane 4402 having a density of 0.912; and Attane 4401 having a density of 0.912. All of these copolymers are commercially available from Dow Chemical co.

The skin layer is prepared in a manner known to those skilled in the art. The ingredients are typically extruded into polymer films. In one embodiment, the skin layer may be prepared from a commercially available synthetic paper concentrate. These concentrates are known to those skilled in the art and include paper  synthetic paper concentrate available from a. Another useful concentrate is available from Ampacet Corporation. When a concentrate is used, the ink adhesion improving polymer is added to the concentrate in the amounts described above.

The following examples relate to skin formulations that can be used to make synthetic paper. In the following examples and elsewhere in the specification and claims, amounts are by weight, temperatures are in degrees celsius, and pressures are atmospheric, unless the context clearly dictates otherwise.

	1	2	3	4	5	6	7	8
									VLDPE	--	--	45	--	30	25	--	35
LLDPE	--	25	--	--	--	--	--	--
									HDPE	20	--	--	--	--	45	--	--
PPa	--	25	--	45	--	--	--	--
									CoPP (3.7% ethylene)	30	--	25	--	--	--	40	--
CaCO3	30	35	20	--	--	15	--	--
									TiO2	20	--	10	--	--	12	--	--
Mica	--	15	--	--	--	3	--	--
									Papermatch	--	--	--	55	70		60	65

a) WRD5-1057 from Union Carbide

Multilayer article

In another embodiment, the present invention relates to a multi-layer article useful as a synthetic paper or label. A multilayer article comprises a polymeric core layer and at least one skin layer, wherein the skin layer comprises (a) a filler, (B) a carrier polymer and (C) a minor amount of an ink adhesion improving polymer. The multilayer article generally has a thickness of from about 1 to about 15, or from about 1.5 to about 10, or from about 2 to about 6 mils.

The polymer core may be a single polymer or a blend of polymers. The polymer core may be a single layer or multiple layers. The polymer cores may be extruded, or coextruded or laminated together to form a multilayer structure. The polymer core may be transparent or colored, such as light colors, including white, yellow, and hazel. The thickness of the core layer is generally from about 60% to about 95%, or from about 65% to about 90%, or from about 70% to about 85% of the thickness of the multilayer article. The core is typically the major portion of the multilayer article. The core typically comprises more than 60%, or more than 65%, or more than 70%, or more than 75% of the thickness of the multilayer article. The skin layer constitutes the remainder of the multilayer article. The core layer typically has a thickness of about 0.1 to about 10 mils, or about 0.3 to about 5, or about 0.5 to about 2.5 mils.

The core layer is composed of at least one polymer. Polymers include those described above for the skin layer. Polyolefins and thermoplastic polymers of ethylene and propylene are particularly useful.

The polymeric core material may contain inorganic fillers and other organic or inorganic additives to provide desired properties such as appearance properties (opaque or colored films), durability and processing characteristics. The nucleating agent can be heated to increase crystallinity and thereby increase stiffness. Examples of useful materials include calcium carbonate, titanium dioxide, metal particles, fibers, flame retardants, antioxidant compounds, heat stabilizers, light stabilizers, ultraviolet light stabilizers, antiblocking agents, processing aids, acid scavengers, and the like.

The core layer may be laminated directly to the skin layer. The structures are those prepared by an extrusion process. In addition, the core layer can be laminated to the skin layer through a tie layer or an adhesive layer. The adhesive can be any of those described below. The tie layer acts on the adhesion promoting layer. The tie layer is typically an adhesive material. The adhesive material may include an adhesive resin such as an ethylene/vinyl acetate copolymer. They include DuPont Elvax 3170 and 3190 LG. Adhesive resins available from DuPont under the trade name Bynel can also be used.

In another embodiment, the multilayer structure includes a second skin layer. The skin layer may be prepared from the polymer for the ink adhesion promoting polymer. The second tie layer is on the other surface of the core layer, i.e. the opposite surface of the ink adhesion promoting polymer. The second skin layer may be an adhesive or a non-adhesive. The second skin layer typically has about the same thickness as the first skin layer. Although they need not be the same thickness, they often have the same thickness.

In one embodiment, the second skin layer is an adhesive layer. The adhesive may be a heat activated adhesive, a hot melt adhesive, or a Pressure Sensitive Adhesive (PSA). Adhesives can be generally classified into the following categories: 1) random copolymer adhesives such as those based on acrylate and/or methacrylate copolymers, alpha-olefin copolymers, silicone copolymers, chloroprene/acrylonitrile copolymers, and the like, 2) block copolymer adhesives including those based on linear block copolymers (i.e., A-B and A-B-A types), branched block copolymers, star block copolymers, graft or radial block copolymers, and the like, and 3) natural and synthetic rubber adhesives. A description of useful binders can be found in Encyclopedia of Polymer Science and Engineering, Vol.13, Wiley-Interscience Publishers (New York, 1988). Descriptions of other useful adhesives can be found in Encyclopedia of Polymer Science and Technology, Vol.1, Interscience Publishers (New York, 1964).

Commercially available pressure sensitive adhesives may be used in the present invention. Examples of such adhesives include hot melt pressure sensitive adhesives available as HM-1597, HL-2207-X, HL-2115X, HL-2193-X from h.b. fuller company, st.paul, minn. Other commercially available pressure sensitive Adhesives that may be used include those available from Century Adhesives Corporation, Columbus, Ohio.

Conventional PSAs may be used, including silicone-based PSAs, rubber-based PSAs, and acrylic PSAs. Another commercial example of a hot melt adhesive is H2187-01, sold by Ato Findley, Inc. of Wauwatusa, Wisconsin. In addition, the rubber-based block copolymer PSAs described in U.S. patent No.3,239,478 (Harlan) can also be utilized in the coextruded adhesive structures of the present invention. The disclosure of this patent on these hot melt adhesives is incorporated herein by reference.

In one embodiment, the pressure sensitive adhesive used in the present invention comprises a rubber-based elastomeric material such as a linear, branched, grafted or radial block copolymer represented by the diblock structure A-B, the triblock A-B-A, the radial or coupled structure (A-B) n and combinations of these, wherein A represents a hard thermoplastic phase or block that is non-rubbery or glassy or crystalline at room temperature but fluid at higher temperatures, and B represents a soft block that is rubbery or elastomeric at the time of use or at room temperature. These thermoplastic elastomers may comprise from about 75 to about 95 weight percent rubbery segments and from about 5 to about 25 weight percent non-rubbery segments.

The non-rubbery segments or hard blocks comprise polymers of mono-and polycyclic aromatic hydrocarbons, more particularly vinyl-substituted aromatic hydrocarbons which may be of monocyclic or bicyclic nature. Preferred rubbery blocks or segments are polymer blocks of homopolymers or copolymers of aliphatic conjugated dienes. Rubbery materials such as polyisoprene, polybutadiene, and styrene-butadiene rubber can be used to form the rubbery block or segment. Particularly preferred rubbery segments include saturated olefin rubbers of polydienes and ethylene/butylene or ethylene/propylene copolymers. The latter rubbers may be obtained from the corresponding unsaturated polyalkylene moieties, such as polybutadiene and polyisoprene, by hydrogenation.

Block copolymers of vinyl aromatic hydrocarbons and conjugated dienes that may be utilized include any of those having elastomeric properties. The block copolymer may be a diblock, triblock, multiblock, radial block, polymeric block, or graft block copolymer. In the present description and claims, the terms diblock, triblock, multiblock, polymeric Block and graft or graft Block in terms of structural features of Block Copolymers are given by the general meaning as defined in the literature, e.g., Encyclopedia of Polymer science and Engineering, Vol.2, (1985) John Wiley & Sons, Inc., New York, 325 + 326, and by J.E.McGrath in Block Copolymers, science technology, Dale J.Meier, Ed., Harwood Academic Publishers, 1979, pages 1-5.

The block copolymer can be polymerized or copolymerized by any known block polymerization or copolymerization procedure, including sequential addition of monomers, incremental addition of monomers, or as described in U.S. patent 3,251,905; 3,390,207, respectively; 3,598,887, respectively; and 4,219,627 by the coupling technique described in. It is well known that tapered copolymer blocks can be incorporated into multi-block copolymers by copolymerizing a mixture of conjugated diene and vinyl aromatic hydrocarbon monomers using a difference in the copolymerization reaction rates of the two. A number of patents describe the preparation of multi-block copolymers containing tapered copolymer blocks, including U.S. patent 3,251,905; 3,639,521; and 4,208,356, the disclosures of which are incorporated herein by reference.

Conjugated dienes that may be used to prepare the polymers and copolymers are those containing from 4 to about 10 carbon atoms and more typically from 4 to 6 carbon atoms. Examples include 1, 3-butadiene, 2-methyl-1, 3-butadiene (isoprene), 2, 3-dimethyl-1, 3-butadiene, chloroprene, 1, 3-pentadiene, 1, 3-hexadiene, and the like. Mixtures of these conjugated dienes may also be used. Preferred conjugated dienes are isoprene and 1, 3-butadiene.

Examples of vinyl aromatic hydrocarbons which may be used to prepare the copolymers include styrene and various substituted styrenes such as o-methylstyrene, p-tert-butylstyrene, 1, 3-dimethylstyrene, α -methylstyrene, β -methylstyrene, p-isopropylstyrene, 2, 3-dimethylstyrene, o-chlorostyrene, p-chlorostyrene, o-bromostyrene, 2-chloro-4-methylstyrene and the like. The preferred vinyl aromatic hydrocarbon is styrene.

Many of the above copolymers of conjugated dienes and vinyl aromatic compounds are commercially available. The number average molecular weight of the block copolymer before hydrogenation is from about 20,000 to about 500,000, preferably from about 40,000 to about 300,000.

The average molecular weight of the individual blocks within the copolymer can vary within certain limits. In most cases, the vinyl aromatic block will have a number average molecular weight of from about 2000 to about 125,000, preferably between about 4000 and 60,000. The conjugated diene blocks before or after hydrogenation have a number average molecular weight of from about 10,000 to about 450,000 and more preferably from about 35,000 to about 150,000.

Also, the vinyl content of the conjugated diene portion before hydrogenation is generally from about 10 to about 80%, and when it is desired that the modified block copolymer exhibit rubbery elasticity, the vinyl content is preferably from about 25 to about 65%, particularly 35 to 55%. The vinyl content of the block copolymer can be determined by nuclear magnetic resonance.

Specific examples of diblock copolymers include styrene-butadiene (SB), styrene-isoprene (SI), and hydrogenated derivatives thereof.

Examples of triblock polymers include styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), alpha-methylstyrene-butadiene-alpha-methylstyrene, and alpha-methylstyrene-isoprene-alpha-methylstyrene. Examples of commercially available block copolymers useful as adhesives include those available under the trade name Kraton polymers from Shell Chemical Company, specific examples include D1101, D1107P, D1111, D1112P, D1113P, D1117P, and D1320X. Vector 4111 is a SIS block copolymer available from Dexco of Houston, Texas.

Upon hydrogenation of the SBS copolymers containing a rubbery segment of a mixture of 1, 4-and 1, 2-isomers, a styrene-ethylene-butylene-styrene (SEBS) block copolymer is obtained. Similarly, hydrogenation of the SIS polymer yields a styrene-ethylene-propylene-styrene (SEPS) block copolymer.

Such polymers and their preparation procedures are described in U.S. Pat. nos. 3,113,986 and 4,226,952, the disclosures of which are incorporated herein by reference.

Many selectively hydrogenated block copolymers are commercially available under the general trade designation "Kraton G" from Shell Chemical Company. One example is Kraton G1652, which is a hydrogenated SBS triblock having about 30 wt% styrene end blocks and a midblock that is a copolymer of ethylene and 1-butene (EB). The low molecular weight variant of G1652 is commercially available from Shell under the name KratonG 1650. Kraton G1651 is another SEBS block copolymer containing about 33 wt% styrene. Kraton G1657 is an SEBS diblock copolymer containing about 13 wt% styrene. The styrene content is lower than that in Kraton G1650 and Kraton G1652.

The block copolymers may also include functionalized polymers such as those obtainable by reacting an alpha, beta-ethylenically unsaturated monocarboxylic or dicarboxylic acid reagent on a selectively hydrogenated block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene as described above. The reaction between the carboxylic acid reagents in the grafted block copolymer can be carried out in solution or by a melt process in the presence of a free radical initiator.

The preparation of various selectively hydrogenated block copolymers of conjugated dienes and vinyl aromatic hydrocarbons that have been grafted with a carboxylic acid reagent is described in a number of patents, including U.S. Pat. nos. 4,578,429; 4,657,970, respectively; and 4,795,782, the disclosures of these patents on graft selectively hydrogenated block copolymers of conjugated dienes and vinyl aromatic compounds and methods for preparing these compounds are incorporated herein by reference. U.S. patent 4,795,782 describes and gives examples of graft block copolymers prepared by solution and melt processes. U.S. patent 4,578,429 contains an example of grafting Kraton G1652(SEBS) polymer with maleic anhydride and 2, 5-dimethyl-2, 5-di (tert-butylperoxy) hexane by melt reaction in a twin screw extruder (see column 8, lines 40-61).

Examples of commercially available maleated selectively hydrogenated copolymers of styrene and butadiene include Kraton FG1901X, FG1921X, and FG1924X, from Shell, often referred to as maleated selectively hydrogenated SEBS copolymers. FG1901X contains 1.7% bound functional group succinic anhydride and about 28% styrene. FG1921X contains approximately 1% bound functional succinic anhydride and 29% styrene. FG1924X contains about 13% styrene and about 1% bound functional succinic anhydride.

Useful block copolymers are also commercially available from Nippon Zeon Co., 2-1, Marunochi, Chiyoda-Ku, Tokyo, Japan. For example, Quintac 3530 is available from nippon zeon and is believed to be a linear styrene-isoprene-styrene block copolymer.

Emulsion and solvent-based styrenic PSAs are known, for example, from U.S. Pat. Nos. 5,639,811 and 5,164,444, respectively, the disclosures of which are incorporated herein by reference. When an emulsion of the film material and/or adhesive composition is used, the water in the extruder may be removed by using the method described and claimed in U.S. patent 5,716,669(LaRose et al).

In addition, the adhesive composition may also contain at least one solid tackifier resin component. A solid tackifier is defined herein as a tackifier having a softening point above 80 ℃. When present, the adhesive composition generally comprises from about 40 to about 80 wt% of the thermoplastic elastomer component and from about 20 to about 60 wt% (or from about 55 to 65 wt%) of the solid tackifier resin component. Common solid tackifier resins include hydrocarbon resins, rosins, hydrogenated rosins, rosin esters, polyterpene resins, and other resins having a suitable balance of properties. A wide variety of useful solid tackifier resins are commercially available, such as terpene resins sold under the trademark Zonatec by Arizona Chemical Company, and petroleum hydrocarbon resins, such as resins sold under the trademark Escorez by Exxon Chemical Company. Examples of useful solid tackifiers include Escorez 2596, Escorez 1310LC, and Wingtack 95, a synthetic tackifier resin available from Goodyear, Akron, Ohio.

The adhesive composition may also contain a liquid rubber. Liquid rubbers are those rubbers that are liquid at room temperature. The liquid rubber typically has a Mw of at least 5,000 and more typically at least 20,000. Incorporation of the liquid rubber in an amount of less than 10 wt%, even less than 5 wt%, based on the total weight of the adhesive formulation, results in an adhesive that is co-extrudable with the polymeric core material. Liquid block copolymers such as liquid styrene-isoprene block copolymers are particularly useful. Examples of commercially available rubbers include Kraton LVSI-101 available from Shell Chemical Company, and Isolene D-400 available from Elementis Performance Polymers, Belleville, N.J.

In another embodiment, the second skin layer is a heat seal layer. The heat-sealable layer is typically comprised of a heat-activatable material. They include polyolefins (linear or branched); polyamides such as nylon; a polyester copolymer; polyurethane thermoplastic adhesives including polyurethane polyesters and polyurethane polyethers; ionomers based on sodium or zinc salts of ethylene-methacrylic acid; polyacrylonitrile; and ethylene-vinyl acetate copolymers. Another useful heat-activatable adhesive is an unsaturated polyester with a heat-activated curing agent such as a blocked isocyanate. Included in the ethylene-vinyl acetate copolymer are acrylates such as ethylene-methacrylic acid, ethylene-methyl acrylate, ethylene-acrylic acid and ethylene-ethyl acrylate. Also included in useful binders are olefin monomer polymers and copolymers having, for example, from 2 to about 12 carbon atoms, and in one embodiment from 2 to about 8 carbon atoms. They include polymers of alpha-olefins having from 2 to about 4 carbon atoms per molecule. These include polyethylene, polypropylene, poly-1-butene, and the like. An example of a copolymer within the above definition is a copolymer of ethylene and 1-butene having from about 1 to about 10 weight percent of the 1-butene comonomer incorporated into the copolymer molecule. Polyolefins include amorphous polyolefins. Useful polyethylenes have various densities, including the low, medium and high density ranges as defined above. Ethylene/methyl acrylate copolymer available from Chevron under the trade name EMAC can be used. They included EMAC2260, which had a methyl acrylate content of 24 wt% and a melt index of 2.0g/10min @190 deg.C, 2.16Kg, and EMAC SP 2268T, which also had a methyl acrylate content of 24 wt% and a melt index of 10g/10min, 190 deg.C, 2.16 Kg. Polymeric film materials prepared from blends of copolymers or blends of copolymers with homopolymers may also be used. The heat activated layer may contain an Ultraviolet (UV) absorber or other light stabilizer. These additives are introduced for the purpose of preventing degradation due to sunlight. One class of useful stabilizers are hindered amine light stabilizers, including those previously described.

In one embodiment of the present invention, the heat-activatable adhesive layer comprises a polyurethane adhesive that is the reaction product of an organic polyisocyanate such as hexamethylene diisocyanate, toluene diisocyanate, diphenyl diisocyanate, tetramethylene diisocyanate, toluene triisocyanate, triphenylmethyl triisocyanate, polyaryl polyisocyanates, and the like, with an active hydrogen-containing compound such as those containing hydroxyl and/or amino groups, e.g., diols, polyols, hydroxylated polyesters, diamines, and the like. The polyurethane adhesive may contain an adhesion promoter selected from the group consisting of N-substituted-2-pyrrolidones and ethoxylated alkylphenols.

In another embodiment of the invention, the heat activatable adhesive layer is a linear saturated polyester polymer that includes a heat activated curing agent. The uncured polyester itself is a linear alkyl saturated polyester formed by reacting a diol with a diacid. The molecular weight of the uncured polyester polymer must be low enough to flow and wet the surface of the substrate at the application temperature, i.e., generally below 400 ° F. In one embodiment, the molecular weight is in the range of about 5,000 to about 30,000, and in another embodiment, the molecular weight is in the range of about 10,000 to about 15,000. The polyester adhesive includes a heat activated curing agent, such as a heat activated polyisocyanate curing agent. Suitable diols include ethylene glycol, propylene glycol, 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 1, 8-octanediol, 1, 4-cyclohexanedimethanol, 1, 3-cyclohexanedimethanol, diethylene glycol, and the like. Diacids useful in the preparation of these polymers include aromatic dicarboxylic acids free of vinyl unsaturation such as isophthalic acid or isophthalic anhydride, phthalic acid or phthalic anhydride, terephthalic acid or aliphatic dicarboxylic acids such as adipic acid, succinic acid, glutaric acid, and the like.

Heat activated curing agents are used to cure polyesters upon heating. The thermally activated curing agent can be an isocyanate curing agent, preferably a blocked isocyanate curing agent. Suitable such curing agents include phenol blocked methylene bis-4-phenyl isocyanates such as those disclosed in U.S. patent No.3,307,966 and phenolic blocked polyisocyanates such as those described in U.S. patent No.3,226,276. Other blocked isocyanates include dimeric toluene diisocyanate and methyl ethyl-ketoxime blocked isocyanate. A useful adhesive is Bostik adhesive 10-300-3, which is a thermosetting linear saturated polyester adhesive using an isocyanate curing agent and a polyester formed from ethylene glycol and methyl terephthalic acid. The blocked isocyanate/uncured linear polyester is dissolved in methyl ethyl ketone and methylene chloride and has a weight average molecular weight of 10,000 to 15,000.

In one embodiment, the multilayer article includes a single skin layer on one surface of the core. In another embodiment, the multilayer article includes two skin layers on each surface of the core. In this embodiment, one of the skin layers is an adhesive layer, such as a pressure sensitive adhesive layer. A releasable liner may be present on the pressure sensitive adhesive to protect the adhesive. In another aspect of the invention, the core layer has skin layers on each of its surfaces. The second skin layer is tack-free. In this embodiment, another adhesive or heat-sealable layer may be attached to the second skin layer. Additionally, in all of the above embodiments, the core may be attached directly to the skin layers, for example when they are coextruded. The core may be attached to the skin layer by an intermediate adhesive layer. This layer may consist of the above adhesive or heat-sealable material. The layer may also be a tie layer. The tie layer is used to promote adhesion between the core and the skin. They include DuPont Elvax 3170 and 3190 LG. Adhesive resins available from DuPont under the trade name Bynel can also be used. They include ethylene/vinyl acetate resins available under the trade name Series 1100, acid-modified ethylene-acrylate polymers (Series 2000), anhydride-modified ethylene acrylate copolymers (Series 2100), anhydride-modified ethylene/vinyl acetate copolymers (Series 3000), acid-and acrylate-modified ethylene/vinyl acetate resins (Series 3100), anhydride-modified ethylene/vinyl acetate copolymers (Series 3800), anhydride-modified ethylene/vinyl acetate resins (Series 3900), anhydride-modified high density polyethylene resins (Series 4000), anhydride-modified linear low density polyethylene resins (Series4100), anhydride-modified low density polyethylene resins (Series 4200), and anhydride-modified polyacrylic resins (Series 5000). Bynel CXA 1123, an ethylene/vinyl acetate copolymer having a melting point of 74 ℃, and Bynel CXA 3101, an ethylene-based polymer containing ester and acidic comonomer functional groups and having a melting point of 87 ℃ can be used.

The multilayer articles may be prepared by lamination of layers or extrusion of layers, including coextrusion. In one embodiment, the multilayer article is prepared using three extruders. The extruders are designated A, B and C, where a denotes the ink adhesion promoting polymer, B denotes the polymer core, and C denotes the second skin layer. Each temperature within the extruder is approximately equal to the melting point of each resin located within that particular extruder. The temperature of the extruder is as follows:

extruder A, 350 ℃ F. and 500 ℃ F

Extruder B, 350 ℃ and 550 DEG F

Extruder C, 325 ℃ F. and 450 ℃ F

Extrusion head pressures associated with extrusion processes of this nature are typically in the range of 1,000 to 5,500psi, but vary depending on the structural design, polymer type, and process conditions. The extruder feeds a combining device prior to entering the slot die where the polymer streams are fed as a melt and combined into the desired layers (i.e., 2-layer structure, 3-layer structure, etc.). The melt exits the slot die at a nominal thickness greater than the desired thickness of the base film (base film). The volumetric flow rate of the polymer melt relative to the resin of the cooled casting roll is the mechanism for controlling the final film thickness.

On the production line, there is a blade that cuts a small portion of the film (typically 2-6 inches) at the outer edge to obtain a film with a uniform, clean edge. The film is finally self-wound onto a core in roll form.

The following examples illustrate the multilayer articles of the present invention. All examples were prepared by coextrusion of the layers as described above.

Example A

By mixing a skin layer of Ex5 with a composition comprising 50 wt% of a propylene copolymer (3.7% ethylene), 30 wt% of a blend containing 30% TiO₂And 70% of an ethylene-methacrylate carrier₂The concentrate, and the polymer core composition of 20% calcium carbonate concentrate were co-extruded to produce a two-layer article. The thickness of each layer was: 10% of the skin layer and 90% of the core layer.

Example B

A three-layer article was prepared by co-extruding the skin layer of Ex5, the core of example a and a second skin layer comprising 50% propylene homopolymer and 50% ethylene vinyl acetate (18% vinyl acetate). The thickness of each layer is as follows: 10% of each skin layer and 80% of the core layer.

While the invention has been described in terms of preferred embodiments, it is to be understood that various modifications thereof will become apparent to those skilled in the art upon reading the specification. It is therefore understood that the invention disclosed herein encompasses all such variations as fall within the scope of the appended claims.

Claims (38)

1. A polymeric film for use as a skin layer in synthetic paper or labels comprising (A) a filler, (B) a carrier polymer and (C) a minor amount of an ink adhesion improving polymer.

2. The film of claim 1 wherein (a) is an inorganic powder.

3. The film of claim 1 wherein (a) is calcium carbonate, titanium dioxide, clay, diatomaceous earth, talc, mica, barium sulfate, aluminum sulfate, silica, or a mixture of two or more thereof.

4. The film of claim 1 wherein (B) is a polyolefin, a thermoplastic polymer of ethylene and propylene, a polyester, a polycarbonate, a styrene derived polymer, a polyurethane, a polyacryl, a polymethacryloyl, a polyvinyl alcohol, a polyamide, a polyimide, a polysulfone, a polymethylpentene, a polyacetal, a vinyl halide derived polymer, a poly (ethylene-vinyl alcohol), a vinyl acetate derived polymer, an ionomer, and mixtures thereof.

5. The film of claim 1 wherein (B) is a polyolefin, or a thermoplastic polymer of ethylene or propylene, or a mixture comprising such polymers.

6. The film of claim 1 wherein (C) is a polyolefin, a thermoplastic polymer of ethylene and propylene, a polyurethane, a polyvinyl alcohol, a vinyl acetate homopolymer, copolymer or terpolymer, an ionomer, and mixtures thereof.

7. The film of claim 1 wherein (C) is a polyolefin, or a thermoplastic polymer of ethylene or propylene, or a mixture comprising such polymers.

8. The film of claim 1 wherein (C) is polyethylene, polypropylene, a thermoplastic polymer of ethylene or propylene.

9. A polymeric film for use as a skin layer of synthetic paper or label comprising (A) an inorganic filler, (B) a carrier resin and (C) a minor amount of an ink adhesion improving polyolefin, a thermoplastic polymer of ethylene or propylene, or a mixture of two or more thereof.

10. A multilayer article for use as a synthetic paper or label comprising a polymeric core layer having first and second surfaces and at least one skin layer on the first surface of the core layer, wherein the skin layer comprises (a) a filler, (B) a carrier polymer and (C) a minor amount of an ink adhesion improving polymer.

11. The film of claim 10 wherein (a) is an inorganic powder.

12. The film of claim 10 wherein (a) is calcium carbonate, titanium dioxide, clay, diatomaceous earth, talc, mica, barium sulfate, aluminum sulfate, silica, or a mixture of two or more thereof.

13. The film of claim 10 wherein (B) is a polyolefin, a thermoplastic polymer of ethylene and propylene, a polyester, a polycarbonate, a styrene derived polymer, a polyurethane, a polyacryl, a polymethacryloyl, a polyvinyl alcohol, a polyamide, a polyimide, a polysulfone, a polymethylpentene, a polyacetal, a vinyl halide derived polymer, a poly (ethylene-vinyl alcohol), a vinyl acetate derived polymer, an ionomer, and mixtures thereof.

14. The film of claim 10 wherein (B) is a polyolefin, or a thermoplastic polymer of ethylene or propylene, or a mixture comprising such polymers.

15. The film of claim 10 wherein (C) is a polyolefin, a thermoplastic polymer of ethylene or propylene, a polyurethane, a polyvinyl alcohol, a vinyl acetate homopolymer, copolymer or terpolymer, an ionomer, and mixtures thereof.

16. The film of claim 10 wherein (C) is a polyolefin, or a thermoplastic polymer of ethylene or propylene, or a mixture comprising such polymers.

17. The film of claim 10 wherein (C) is polyethylene, polypropylene, a thermoplastic polymer of ethylene or propylene.

18. The article of claim 10, wherein the polymer core is a polyolefin, a thermoplastic polymer of ethylene and propylene, a polyester, a polycarbonate, a styrene derived polymer, a polyurethane, a polyacryl, a polymethacryloyl, a polyvinyl alcohol, a polyamide, a polyimide, a poly (ethylene-vinyl alcohol), a polyacetal, a polysulfone, a vinyl acetate derived polymer, a vinyl halide derived polymer, an ionomer, and mixtures thereof.

19. The article of claim 10 wherein the polymeric core is a polyolefin, a thermoplastic polymer of ethylene or propylene, or a mixture of two or more thereof.

20. The article of claim 10, further comprising a filler in the polymer core.

21. The article of claim 20 wherein the filler is an inorganic powder.

22. The film of claim 20 wherein the filler is calcium carbonate, titanium dioxide, clay, diatomaceous earth, talc, mica, barium sulfate, aluminum sulfate, silica, or a mixture of two or more thereof.

23. The article of claim 10, further comprising a second skin layer on a second surface of the polymeric core layer.

24. The article of claim 23, wherein the second skin layer is a polyolefin, a thermoplastic polymer of ethylene and propylene, a polyester, a polycarbonate, a styrene derived polymer, a polyurethane, a polyacryl, a polymethacryloyl, a polyvinyl alcohol, a polyamide, a poly (ethylene-vinyl alcohol), a vinyl acetate derived polymer, an ionomer, and mixtures thereof.

25. The article of claim 23 wherein the skin layers are made from the same polymer.

26. The article of claim 23, wherein the second skin layer is a heat seal layer.

27. The article of claim 23 wherein the second skin layer is a pressure sensitive adhesive layer.

28. A multilayer article for use as a synthetic paper or label comprising a polymeric core layer having first and second surfaces and at least one skin layer on the first surface of the core layer, wherein the skin layer of the synthetic paper or label comprises (a) an inorganic filler, (B) a carrier resin and (C) a minor amount of an ink adhesion improving polyolefin, a thermoplastic polymer of ethylene or propylene, or a mixture of two or more thereof.

29. The article of claim 28, wherein the polymer core is a polyolefin, a thermoplastic polymer of ethylene and propylene, a polyester, a polycarbonate, a styrene derived polymer, a polyurethane, a polyacryl, a polymethacryloyl, a polyvinyl alcohol, a polyamide, a polyimide, a poly (ethylene-vinyl alcohol), a polyacetal, a polysulfone, a vinyl acetate derived polymer, a vinyl halide derived polymer, an ionomer, and mixtures thereof.

30. The article of claim 28 wherein the polymeric core is a polyolefin, a thermoplastic polymer of ethylene or propylene, or a mixture of two or more thereof.

31. The article of claim 28, further comprising a filler in the polymer core.

32. The article of claim 32 wherein the filler is an inorganic powder.

33. The film of claim 32 wherein the filler is calcium carbonate, titanium dioxide, clay, diatomaceous earth, talc, mica, barium sulfate, aluminum sulfate, silica, or a mixture of two or more thereof.

34. The article of claim 28, further comprising a second skin layer on a second surface of the polymeric core layer.

35. The article of claim 34, wherein the second skin layer is a polyolefin, a thermoplastic polymer of ethylene and propylene, a polyester, a polycarbonate, a styrene derived polymer, a polyurethane, a polyacryl, a polymethacryloyl, a polyvinyl alcohol, a polyamide, a poly (ethylene-vinyl alcohol), a vinyl acetate derived polymer, an ionomer, and mixtures thereof.

36. The article of claim 34 wherein the skin layers are made of the same polymer.

37. The article of claim 34, wherein the second skin layer is a heat seal layer.

38. The article of claim 34 wherein the second skin layer is a pressure sensitive adhesive layer.