Films containing polylactic acid polymers suitable for graphic articles

Abstract

Articles are described that include a first film layer comprising a polylactic acid polymer (semicrystalline polylactic acid polymer, amorphous polylactic acid polymer, or a mixture thereof), a second (e.g., polyvinyl acetate) polymer having a Tg of at least 25°C, and a plasticizer. In some embodiments, the film layer further comprises an inorganic pigment and / or a hydrolysis stabilizer. In other embodiments, the film has a net endotherm of melting ΔH of less than 10 J / g. nm1 A method for making the graphic film is also described.

Description

[Background technology]

[0001] WO 2017 / 222824 describes graphic articles comprising semi-crystalline polylactic acid-based films. Summary of the Invention

[0002] In one embodiment, an article is described that includes a first film layer comprising a polylactic acid polymer (e.g., a semicrystalline polylactic acid polymer, an amorphous polylactic acid polymer, or a mixture thereof), a second (e.g., polyvinyl acetate) polymer having a Tg of at least 25°C, a plasticizer, and an inorganic pigment in an amount such that the ratio of polylactic acid polymer to inorganic pigment is less than 4.5:1, 4.4:1, 4.3:1, 4.2:1, or 4.1:1. In some embodiments, the inorganic pigment comprises TiO. The amount of inorganic pigment is typically at least 15, 16, 17, 18, 19, or 20% by weight of the first film layer. In some embodiments, the ratio of polylactic acid polymer to inorganic pigment is at least 1:1. In some embodiments, the first film layer further comprises a hydrolysis stabilizer. In some embodiments, the article is a graphic film that further includes a graphic adjacent to a major surface of the film layer.

[0003] In another embodiment, a film layer comprises a semi-crystalline polylactic acid polymer, and optionally an amorphous polylactic acid polymer; Articles are described that include a film layer that includes a second polymer having a Tg of at least 25°C, a plasticizer, and one or more carbodiimide hydrolysis stabilizers. In some embodiments, the article is a graphic film that further includes a graphic adjacent a major surface of the film layer. In typical embodiments, the graphic includes a dried and / or cured ink layer. The ink layer is typically a dried and / or cured radiation-cured ink, an organic solvent-based ink, or a water-based ink. In some embodiments, the film layer is a transparent cover film or backing film. In other embodiments, the film layer is a backing film that further includes an inorganic pigment.

[0004] In other embodiments, a film is formed comprising a polylactic acid polymer (e.g., a semi-crystalline polylactic acid polymer, an amorphous polylactic acid polymer, or a mixture thereof), a second (e.g., polyvinyl acetate) polymer having a Tg of at least 25°C, and a plasticizer, wherein the film has a net melting endotherm ΔH of less than 10 J / g. nm1 In one embodiment, the first film layer (e.g., unannealed) comprises a semi-crystalline polylactic acid polymer, an optional amorphous polylactic acid polymer, and a nucleating agent. In another embodiment, the first film layer comprises an amorphous polylactic acid polymer and an optional semi-crystalline polylactic acid polymer.

[0005] In another embodiment, a method for manufacturing a graphic film comprises the steps of:

[0006] Methods of manufacturing are described that include providing a film comprising a first film layer described herein and providing a graphic on the film. The first film layer can be annealed or unannealed. In some embodiments, the first film layer, upon manufacturing and / or printing, exhibits a net melting endotherm ΔH of less than 10 J / g in a first heating scan. nm1 It has. [Brief explanation of the drawings]

[0006] [Figure 1] 1A-1C are schematic cross-sectional views of various graphic films. [Figure 2] 1A-1C are schematic cross-sectional views of various graphic films. [Figure 3] 1A-1C are schematic cross-sectional views of various graphic films. [Figure 4] 1A-1C are schematic cross-sectional views of various graphic films. [Figure 5] 1A-1C are schematic cross-sectional views of various graphic films. [Figure 6] 1A-1C are schematic cross-sectional views of various graphic films. [Figure 7] 1A-1C are schematic cross-sectional views of various graphic films. [Figure 8] 1A-1C are schematic cross-sectional views of various graphic films. [Figure 9] 1 is a representative DSC profile of a composition containing a nucleating agent, showing a sharp crystallization peak exotherm during cooling. [Figure 10] 1 is a representative DSC profile of a composition without a nucleating agent that did not exhibit a crystallization peak exotherm during cooling. [Figure 11] FIG. 10 shows the results of dynamic mechanical analysis of Example 12. [Figure 12] FIG. 10 shows the results of dynamic mechanical analysis of Example 16. DETAILED DESCRIPTION OF THE INVENTION

[0007] The (e.g., graphic) articles described herein include at least one layer, i.e., a first film layer, comprising a polylactic acid ("PLA") polymer film. Lactic acid is a renewable material obtained by bacterial fermentation of corn starch or cane sugar and is therefore considered a natural, or in other words, "biomass," material. Lactic acid has two optical isomers: L-lactic acid (also known as (S)-lactic acid) and D-lactic acid (also known as (R)-lactic acid), as shown below. [ka]

[0008] Polyesterification of lactic acid produces polylactic acid polymers.

[0009] More typically, lactic acid is converted to cyclic lactide monomer, and the lactide undergoes ring-opening polymerization, as shown below. [ka]

[0010] The resulting polymeric material is typically called a polylactide polymer.

[0011] The degree of crystallinity, and therefore many important properties, is controlled primarily by the ratio of D- and / or meso-lactide to L-cyclic lactide monomers used. Similarly, in polymers prepared by direct polyesterification of lactic acid, the degree of crystallinity is controlled primarily by the ratio of polymerized units derived from D-lactic acid to polymerized units derived from L-lactic acid.

[0012] In some embodiments, the first film layer of the (eg, graphic) articles described herein generally comprises a semi-crystalline PLA polymer, either alone or in combination with an amorphous PLA polymer.

[0013] In some embodiments, semicrystalline PLA polymers typically contain at least 90, 91, 92, 93, 94, or 95% by weight of polymerized units derived from L-lactic acid (e.g., L-lactide) and no more than 10, 9, 8, 7, 6, or 5% by weight of polymerized units derived from D-lactic acid (e.g., D-lactide and / or meso-lactide). In still other embodiments, semicrystalline PLA polymers contain at least 96% by weight of polymerized units derived from L-lactic acid (e.g., L-lactide) and no more than 4, 3, or 2% by weight of polymerized units derived from D-lactic acid (e.g., D-lactide and / or meso-lactide). Similarly, films contain even lower concentrations of polymerized units derived from D-lactic acid (e.g., D-lactide and / or meso-lactide), depending on the concentration of semicrystalline PLA polymer in the film. For example, if a film composition contains 15 wt% semicrystalline PLA having about 2 wt% D-lactide and / or meso-lactide, the film composition contains about 0.3 wt% D-lactide and / or meso-lactide. The film generally contains no more than 9, 8, 7, 6, 5, 4, 3, 2, 1.5, 1.0, 0.5, 0.4, 0.3, 0.2, or 0.1 wt% polymerized units derived from D-lactic acid (e.g., D-lactide and / or meso-lactide). Suitable examples of semicrystalline PLA include Natureworks® Ingeo® 4042D and 4032D. These polymers are described in the literature as having a molecular weight Mw of about 200,000 g / mol, an Mn of about 100,000 g / mol, and a polydispersity index of about 2.0.

[0014] Alternatively, the semicrystalline PLA polymer may contain at least 90, 91, 92, 93, 94, or 95% by weight of polymerized units derived from D-lactic acid (e.g., D-lactide) and no more than 10, 9, 8, 7, 6, or 5% by weight of polymerized units derived from L-lactic acid (e.g., L-lactide and / or meso-lactide). In still other embodiments, the semicrystalline PLA polymer contains at least 96% by weight of polymerized units derived from D-lactic acid (e.g., D-lactide) and no more than 4, 3, or 2% by weight of polymerized units derived from L-lactic acid (e.g., L-lactide and / or meso-lactide). Similarly, films contain even lower concentrations of polymerized units derived from L-lactic acid (e.g., L-lactide and / or meso-lactide), depending on the concentration of semicrystalline PLA polymer in the film. For example, if a film composition contains 15 wt. % semi-crystalline PLA having about 2 wt. % L-lactide and / or meso-lactide, the film composition contains about 0.3 wt. % L-lactide and / or meso-lactide. The film generally contains no more than 9, 8, 7, 6, 5, 4, 3, 2, 1.5, 1.0, 0.5, 0.4, 0.3, 0.2, or 0.1 wt. % polymerized units derived from L-lactic acid (e.g., L-lactide and / or meso-lactide). An example of such semi-crystalline PLA is available as "Synterra® PDLA."

[0015] The first film layer may further comprise an amorphous PLA polymer blended with semi-crystalline PLA. In other embodiments, the first film layer comprises an amorphous PLA polymer, alone or in combination with a low concentration of semi-crystalline PLA, such that the composition and film have a low level of crystallinity. The inclusion of an amorphous PLA polymer may be preferred to improve the printability of the film with organic solvent-based inks.

[0016] In some embodiments, amorphous PLA typically contains 90% or less by weight of polymerized units derived from L-lactic acid and more than 10% by weight of polymerized units derived from D-lactic acid (e.g., D-lactide and / or meso-lactide). In some embodiments, amorphous PLA contains at least 80 or 85% by weight of polymerized units derived from L-lactic acid (e.g., L-lactide). In some embodiments, amorphous PLA contains 20 or 15% or less by weight of polymerized units derived from D-lactic acid (e.g., D-lactide and / or meso-lactide). Suitable amorphous PLA includes Natureworks® Ingeo® 4060D grade. This polymer has been described in the literature as having a molecular weight Mw of approximately 180,000 g / mol.

[0017] Alternatively, amorphous PLA typically contains 90% or less by weight of polymerized units derived from D-lactic acid and more than 10% by weight of polymerized units derived from L-lactic acid (e.g., L-lactide and / or meso-lactide). In some embodiments, amorphous PLA contains at least 80 or 85% by weight of polymerized units derived from D-lactic acid (e.g., D-lactide). In some embodiments, amorphous PLA contains 20 or 15% or less by weight of polymerized units derived from L-lactic acid (e.g., L-lactide and / or meso-lactide).

[0018] In some embodiments, both semi-crystalline and amorphous PLA polymers generally contain a high concentration of polymerized units derived from L-lactic acid (e.g., L-lactide) along with a low concentration of polymerized units derived from D-lactic acid (e.g., D-lactide).

[0019] In other embodiments, both semi-crystalline and amorphous PLA polymers generally contain a high concentration of polymerized units derived from D-lactic acid (e.g., D-lactide) along with a low concentration of polymerized units derived from L-lactic acid (e.g., L-lactide).

[0020] The PLA polymer is preferably a "film-grade" polymer having a melt flow rate (measured according to ASTM D1238) of 25, 20, 15, or 10 g / min or less at 210°C and a mass of 2.16 kg. In some embodiments, the PLA polymer has a melt flow rate of less than 10 or 9 g / min at 210°C. This melt flow rate is related to the molecular weight of the PLA polymer. PLA polymers typically have a weight average molecular weight (Mw) of at least 50,000 g / mol, 75,000 g / mol, 100,000 g / mol, 125,000 g / mol, or 150,000 g / mol, as determined by gel permeation chromatography using polystyrene standards. In some embodiments, the molecular weight (Mw) is no greater than 400,000 g / mol, 350,000 g / mol, or 300,000 g / mol.

[0021] PLA polymers typically have a tensile strength in the range of about 25-150 MPa, a tensile modulus in the range of about 1000-7500 MPa, and a tensile elongation in the range of at least 3, 4, or 5, but not more than about 10 or 15%. In some embodiments, the tensile strength at break of the PLA polymer is at least 30, 35, 40, 45, or 50 MPa. In some embodiments, the tensile strength of the PLA polymer is not more than 125, 100, or 75 MPa. In some embodiments, the tensile modulus of the PLA polymer is at least 1500, 2000, 2500, or 3000 MPa. In some embodiments, the tensile modulus of the PLA polymer is not more than 7000, 6500, 6000, 5500, 5000, or 4000 MPa. Such tensile and elongation properties can be determined according to ASTM D882 and are typically reported by manufacturers or suppliers of such PLA polymers.

[0022] PLA polymers generally have a glass transition temperature, Tg, in the range of about 50-65°C, which can be determined by differential scanning calorimetry (DSC), as described in the Examples below. In some embodiments, the Tg is at least 51, 52, 53, 54, or 55°C.

[0023] Semi-crystalline PLA polymers typically have (e.g., peak) melting points in the range of 140-175° C., 180° C., 185° C., or 190° C. In some embodiments, the (e.g., peak) melting point is at least 145, 150, or 155° C. Typically, PLA polymers comprising semi-crystalline PLA alone or in combination with amorphous PLA polymers can be melt-processed at temperatures of 180, 190, 200, 210, 220, or 230° C.

[0024] In one embodiment, PLA polymer can crystallize to form a stereocomplex (Macromolecules, 1987, 20(4), pp. 904-906). PLA stereocomplexes are formed when PLLA (a PLA homopolymer polymerized primarily from L-lactic acid or L-lactide units) is blended with PDLA (a PLA homopolymer polymerized primarily from D-lactic acid or D-lactide units). PLA stereocomplex crystals are of interest because their melting points range from 210 to 250°C. Stereocomplex PLA crystals with higher melting points increase the thermal stability of PLA-based materials. PLA stereocomplex crystals are also known to effectively nucleate PLA homopolymer crystals (Polymer, Volume 47, Issue 15, July 12, 2006, Page 5430). This nucleation effect increases the overall percent crystallinity of the PLA-based material, which in turn improves the thermal stability of the material.

[0025] The first film layer typically comprises semi-crystalline PLA polymer, or a blend of semi-crystalline PLA and amorphous PLA, or amorphous PLA, in an amount of at least 25, 30, 35, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50% by weight, based on the total weight of the PLA polymer, the second (e.g., polyvinyl acetate) polymer, and the plasticizer. The total amount of PLA polymer is typically no more than 90, 85, 80, 75, or 70% by weight of the total weight of the PLA polymer, the second (e.g., polyvinyl acetate) polymer, and the plasticizer.

[0026] When the film composition includes a blend of semi-crystalline PLA and amorphous PLA, the amount of semi-crystalline PLA is typically at least 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20% by weight, based on the total weight of the PLA polymer, the second (e.g., polyvinyl acetate) polymer, and the plasticizer. In some embodiments, the amount of amorphous PLA polymer ranges from 10, 15, 25, or 30% by weight to 45, 50, 55, or 60% by weight, based on the total weight of the PLA polymer, the second (e.g., polyvinyl acetate) polymer, and the plasticizer. The amount of amorphous PLA polymer may exceed the amount of crystalline PLA polymer. In some embodiments, the weight ratio of amorphous PLA polymer to crystalline PLA polymer is at least 1:1, 1.5:1, 2:1, 2.5:1, 3:1, or 3.5:1. In some embodiments, the weight ratio of amorphous PLA polymer to crystalline PLA polymer is less than or equal to 15:1, 14:1, 13:1, 12:1, 11:1, 10:1, 9:1, 8:1, 7:1, 6:1, 5:1, 4.5:1, or 4:1.

[0027] In other embodiments, the film composition includes an amorphous PLA polymer alone or in combination with a low concentration of a semi-crystalline PLA polymer, in which the amount of semi-crystalline PLA polymer may be 0, or less than 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 weight percent based on the total weight of the PLA polymer, the second (e.g., polyvinyl acetate) polymer, and the plasticizer.

[0028] The film composition further includes a second polymer, such as a polyvinyl acetate polymer, that can improve the compatibility of the PLA with the plasticizer, such that the concentration of the plasticizer (as determined by the test method described in the Examples below) can be increased without plasticizer migration.

[0029] The second (e.g., polyvinyl acetate) polymer has a Tg of at least 25° C., 30° C., 35° C., or 40° C. The Tg of the second (e.g., polyvinyl acetate) polymer is typically no greater than 80, 75, 70, 65, 60, 55, 50, or 45° C.

[0030] The second (e.g., polyvinyl acetate) polymer typically has a weight or number average molecular weight (determined by size exclusion chromatography using polystyrene standards) of at least 50,000 g / mol, 75,000 g / mol, 100,000 g / mol, 125,000 g / mol, 150,000 g / mol, 175,000 g / mol, 200,000 g / mol, 225,000 g / mol, or 250,000 g / mol. In some embodiments, the molecular weight (Mw) is less than or equal to 2,000,000 g / mol, 1,500,000 g / mol, 1,000,000 g / mol, 750,000 g / mol, 500,000 g / mol, 450,000 g / mol, 400,000 g / mol, 350,000 g / mol, or 300,000 g / mol. In some embodiments, the molecular weight of the second (e.g., polyvinyl acetate) polymer is higher than the molecular weight of the PLA polymer. In one embodiment, the second (e.g., polyvinyl acetate) polymer has a viscosity of 10 to 50 or 100 mPa. * In another embodiment, the second (e.g., polyvinyl acetate) polymer may be characterized as having a viscosity in a 10 wt % ethyl acetate solution at 20° C. in the range of 5 to 20 mPa. * The composition can be characterized as having a viscosity in a 5 wt % ethyl acetate solution at 20°C in the range of 0.15 to 1.05 s.

[0031] In some advantageous embodiments, the second polymer is a polyvinyl acetate polymer. Polyvinyl acetate polymers are typically homopolymers. However, the polymer may contain relatively low concentrations of repeat units derived from other comonomers, provided that the Tg of the polyvinyl acetate polymer is within the aforementioned range. Examples of other comonomers include acrylic monomers such as acrylic acid and methyl acrylate, vinyl monomers such as vinyl chloride and vinylpyrrolidone, and C2-C8 alkylene monomers such as ethylene. The total concentration of repeat units derived from other comonomers in the polyvinyl acetate polymer is typically 10, 9, 8, 7, 6, or 5 wt. % or less. In some embodiments, the concentration of repeat units derived from other comonomers in the polyvinyl acetate polymer is typically 4, 3, 2, 1, or 0.5 wt. % or less. The polyvinyl acetate polymer is typically hydrolyzed to a low degree. The polymerized units of the polyvinyl acetate polymer that are hydrolyzed to vinyl alcohol units generally represent no more than 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, or 0.5 mole percent of the polyvinyl acetate polymer.

[0032] Polyvinyl acetate polymers are commercially available from a variety of suppliers, including those under the tradenames VINNAPAS® (Wacker) and VINAVIL (Vinavil Americas Corporation, West Chicago, IL). Prior to combination with PLA, such polyvinyl acetate polymers are often in the form of a solid powder (e.g., white) or colorless beads. In some embodiments, the polyvinyl acetate polymer (e.g., a powder prior to combination with the PLA polymer) is not water-redispersible.

[0033] A single second (eg, polyvinyl acetate) polymer or a combination of two or more second (eg, polyvinyl acetate) polymers can be utilized.

[0034] The total amount of second (e.g., polyvinyl acetate) polymer present in the first film layer described herein is at least about 5, 6, 7, 8, 9, or 10 wt. % and typically no more than about 50, 45, or 40 wt. % based on the total weight of the PLA polymer, second (e.g., polyvinyl acetate) polymer, and plasticizer. In some embodiments, the concentration of second (e.g., polyvinyl acetate) polymer is present in an amount of at least 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 wt. %.

[0035] In some embodiments, the first film layer (e.g., composition) has a Tg of less than 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, or 20° C. The first film layer exhibits no plasticizer migration when aged at 80° C. for 24 hours (according to the test method described in the Examples). These properties are due to the inclusion of a second (e.g., polyvinyl acetate) polymer.

[0036] The first film layer further comprises a plasticizer. The total amount of plasticizer in the film composition typically ranges from about 5% to about 30, 35, 40, 45, or 50% by weight, based on the total weight of the PLA polymer, the second (e.g., polyvinyl acetate) polymer, and the plasticizer. In some embodiments, the concentration of plasticizer is at least 6, 7, 8, 9, 10, 11, 12, 13, 14, or 15% by weight of the film composition. In some embodiments, the concentration of plasticizer is no more than 25, 24, 23, 22, 21, 20, 19, 18, 17, 16, 15, or 10% by weight of the film composition.

[0037] A variety of plasticizers capable of plasticizing PLA have been described in the art. Plasticizers are generally liquid at 25° C. and typically have a molecular weight ranging from about 200 g / mol to 10,000 g / mol. In some embodiments, the molecular weight of the plasticizer is 5,000 g / mol or less. In other embodiments, the molecular weight of the plasticizer is 4,000, 3,000, 2,000, or 1,000 g / mol or less. Various combinations of plasticizers can be utilized.

[0038] In some embodiments, the plasticizer does not include lactide (eg, polymerized) moieties.

[0039] The plasticizer preferably contains one or more alkyl ester or aliphatic ester or ether groups. Typically, multifunctional esters and / or ethers are preferred. These include alkyl phosphate esters, dialkyl ether diesters, tricarboxylic acid esters, epoxidized oils and esters, polyesters, polyglycol diesters, alkyl alkyl ether diesters, aliphatic diesters, alkyl ether monoesters, citrate esters, dicarboxylic acid esters, vegetable oils and their derivatives, and esters of glycerin. Such plasticizers are generally free of aromatic groups and halogen atoms and are expected to be biodegradable. Such plasticizers typically contain C2-C6 alkyl esters. 10 The alkyl group further comprises a linear or branched alkyl end group having a carbon chain length of

[0040] In one embodiment, the plasticizer has the following formula (I): [ka] [In the formula, R are independently alkyl groups, which may be the same or different; R' is H or (C1-C 10 ) acyl group.] It is a bio-based citric acid plasticizer represented by the formula:

[0041] R is typically independently C1 to C 10In some embodiments, R is a straight chain or branched alkyl group having a carbon chain length of C2 to C8 or C2 to C4. In some embodiments, R' is acetyl. In other embodiments, at least one R is a branched alkyl group having a carbon chain length of C5 or greater. In some embodiments, the branched alkyl group has a carbon chain length of 8 or less.

[0042] Representative citric acid plasticizers include, for example, triethyl citrate, acetyl triethyl citrate, tributyl citrate, acetyl tributyl citrate, trihexyl citrate, acetyl trihexyl citrate, trioctyl citrate, acetyl trioctyl citrate, butyryl trihexyl citrate, acetyl tris-3-methylbutyl citrate, acetyl tris-2-methylbutyl citrate, acetyl tris-2-ethylhexyl citrate, and acetyl tris-2-octyl citrate. Another representative citric acid plasticizer is acetyl tri-n-butyl citrate, available from Vertellus Specialties, Incorporated (Indianapolis, IN) under the trade name CITROFLEX A-4 PLASTICIZER.

[0043] In another embodiment, the plasticizer comprises a polyethylene glycol backbone and ester alkyl end groups. The molecular weight of the polyethylene glycol segment is typically at least 100, 150, or 200 g / mol and no more than 1,000 g / mol. In some embodiments, the polyethylene glycol segment has a molecular weight of no more than 900, 800, 700, or 600 g / mol. Examples include polyethylene glycol (400) di-ethylhexanoate, available from Hallstar (Chicago, IL) under the trade name "TegMe® 809," and tetraethylene glycol di-ethylhexanoate, available from Hallstar (Chicago, IL) under the trade name "TegMe® 804."

[0044] In another embodiment, the plasticizer can be characterized as a polymeric adipate (i.e., a polyester derived from adipic acid), such as that commercially available as Admex® 6995 from Eastman (Kingsport, TN).

[0045] In another embodiment, the plasticizer is a substituted or unsubstituted aliphatic polyester, such as those described in US Pat. No. 8,158,731, incorporated herein by reference.

[0046] In some embodiments, the aliphatic polyester plasticizer comprises repeat units derived from succinic acid, glutaric acid, adipic acid, and / or sebacic acid. In some embodiments, the polyester of the polymer blends disclosed herein comprises repeat units derived from 1,3-propanediol and / or 1,2-propanediol. In some embodiments, the polyester of the polymer blends disclosed herein comprises one or two terminator units derived from 1-octanol, 1-decanol, and / or mixtures thereof. In some embodiments, the polyester of the polymer blends disclosed herein comprises repeat units derived from succinic acid, glutaric acid, adipic acid, and / or sebacic acid, repeat units derived from 1,3-propanediol and / or 1,2-propanediol, and one or two terminator units derived from 1-octanol, 1-decanol, and / or mixtures thereof.

[0047] In some embodiments, the aliphatic polyester plasticizer has the formula: [ka] [Wherein, n is 1 to 1000, and R 1 is selected from the group consisting of a covalent bond and a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 18 carbon atoms; R 2 is a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 20 carbon atoms, and X 1 -OH, -O2C-R1 -CO2H and -O2C-R 1 -CO2R 3 and X is selected from the group consisting of 2 -H, -R 2 -OH, and R 3 and R 3 is a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 20 carbon atoms. In some embodiments, the polyester has the above formula, except that X 1 is -OH or -O2C-R 1 -CO2H, where X 2 is R 3 is.

[0048] The number of repeating units, n, is selected so that the aliphatic polyester plasticizer has the aforementioned molecular weight.

[0049] In some embodiments, R 1 , R 2 and / or R 3 is an alkyl group. 1 The alkyl group can have, for example, 1 to 18 carbon atoms, 1 to 10 carbon atoms, 1 to 8 carbon atoms, 2 to 7 carbon atoms, 2 to 6 carbon atoms, 2 to 5 carbon atoms, 2 to 4 carbon atoms, and / or 3 carbon atoms. 1 R can be selected from the group consisting of —(CH)—, —(CH)—, —(CH)—, and —(CH)—. 2 The alkyl group can have, for example, 1 to 20 carbon atoms, 1 to 10 carbon atoms, 1 to 8 carbon atoms, 2 to 7 carbon atoms, 2 to 6 carbon atoms, 2 to 5 carbon atoms, 2 to 4 carbon atoms, and / or 3 carbon atoms. 2 R can be selected from the group consisting of -(CH2)3-, -CH2CH(CH3)-, and -CH(CH3)CH2-. 3 The alkyl group can have, for example, 1 to 20 carbon atoms, 1 to 18 carbon atoms, 2 to 16 carbon atoms, 3 to 14 carbon atoms, 4 to 12 carbon atoms, 6 to 12 carbon atoms, 8 to 12 carbon atoms, and / or 8 to 10 carbon atoms.3 may also be a mixture containing -(CH2)7CH3 and -(CH2)9CH3.

[0050] In some embodiments, R 1 is an alkyl group having 1 to 10 carbon atoms, and R 2 is an alkyl group having 1 to 10 carbon atoms, and R 3 is an alkyl group having 1 to 20 carbon atoms. In other embodiments, R 1 is an alkyl group having 2 to 6 carbon atoms, and R 2 is an alkyl group having 2 to 6 carbon atoms, and R 3 is an alkyl group having 8 to 12 carbon atoms. In yet another embodiment, R 1 is an alkyl group having 2 to 4 carbon atoms, and R 2 is an alkyl group having 2 to 3 carbon atoms, and R 3 is an alkyl group having 8 to 10 carbon atoms. In yet another embodiment, R 1 is selected from the group consisting of —(CH)—, —(CH)—, —(CH)—, and —(CH)—; R 2 is selected from the group consisting of -(CH2)3-, -CH2CH(CH3)-, and -CH(CH3)CH2-; R 3 is a mixture containing -(CH2)7CH3 and -(CH2)9CH3.

[0051] Aliphatic polyester plasticizers can have an acid number of from about 0 to about 20 or more. The acid number of a polyester can be determined by known methods, measuring the number of milligrams of potassium hydroxide required to neutralize the free acid in 1 gram of polyester sample.

[0052] Plasticizers with low acid numbers are typically preferred for the shelf-life stability and / or durability of the film. In some embodiments, it is preferred that the acid number of the plasticizer is 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 or less.

[0053] The aliphatic polyester plasticizer can have a hydroxyl number of from about 0 to about 110, e.g., from about 1 to about 40, from about 10 to about 30, from about 15 to about 25, from about 30 to about 110, from about 40 to about 110, from about 50 to about 110, and / or from about 60 to about 90. The polyester can also have a hydroxyl number greater than about 110. The hydroxyl number of the polyester can be determined by known methods for measuring hydroxyl groups, such as the method described in ASTM Test Method D4274.

[0054] One exemplary aliphatic polyester plasticizer is available from Hallstar (Chicago, IL) under the trade name HALLGREEN R-8010®.

[0055] In some embodiments, the plasticizer compound typically has few or no hydroxyl groups. In some embodiments, the weight percent of hydroxyl groups relative to the total weight of the plasticizer compound is 10, 9, 6, 7, 6, 5, 4, 3, 2, 1 or less. In some embodiments, the plasticizer compound does not contain hydroxyl groups. Thus, in this embodiment, the plasticizer is neither glycerol nor water.

[0056] A nucleating agent may also be present in the PLA film composition to accelerate the crystallization rate (e.g., of semi-crystalline PLA). Suitable nucleating agents include, for example, inorganic minerals, organic compounds, salts of organic acids and imides, finely divided crystalline polymers with melting points higher than the processing temperature of PLA, and combinations of two or more of the foregoing. Suitable nucleating agents typically have an average particle size of at least 25 nanometers, or at least 0.1 microns. Combinations of two or more different nucleating agents may also be used.

[0057] Examples of useful nucleating agents include, for example, talc (hydrous magnesium silicate - H2Mg3(SiO3)4 or Mg3SiO4). 10(OH)2), silica (SiO2), titania (TiO2), alumina (Al2O3), zinc oxide, saccharin sodium salt, calcium silicate, sodium benzoate, calcium titanate, aromatic sulfonate derivatives, boron nitride, copper phthalocyanine, phthalocyanine, saccharin sodium salt, isotactic polypropylene, polybutylene terephthalate, etc.

[0058] When an organic nucleating agent is present, the nucleating agent is typically present at a concentration ranging from at least about 0.01, 0.02, 0.03, 0.04, 0.05, 0.1, 0.15, or 0.2 wt. % to no more than about 1, 2, 3, 4, or 5 wt. % based on the total weight of the film composition. Concentrations may be higher when the nucleating agent is an inorganic oxide filler such as silica, alumina, zinc oxide, and talc.

[0059] In one embodiment, the nucleating agent can be characterized as a salt of a phosphorus-containing aromatic organic acid, such as zinc phenylphosphonate, magnesium phenylphosphonate, disodium 4-tert-butylphenylphosphonate, and sodium diphenylphosphinate.

[0060] One advantageous nucleating agent has the formula: [ka] and is available from Nissan Chemical Industries, Ltd. under the trade name "Ecopromote."

[0061] In some embodiments, inorganic fillers can be used to prevent film layers or rolls from blocking or sticking during storage and transportation. Inorganic fillers include clays and inorganic minerals, either surface-modified or not. Examples include talc, diatomaceous earth, silica, mica, kaolin, titanium dioxide, perlite, and wollastonite.

[0062] Organic biomaterial fillers include various forest and agricultural products, either modified or unmodified. Examples include cellulose, wheat, starch, modified starch, chitin, chitosan, keratin, agriculturally derived cellulosic materials, gluten, flour, and guar gum. The term "flour" generally refers to a film composition having a protein-containing fraction and a starch-containing fraction derived from the same plant source, where the protein-containing fraction and the starch-containing fraction are not separated from each other. Typical proteins present in flour are globulins, albumins, glutenins, secalins, prolamins, and glutelins. In typical embodiments, the first film layer contains little or no organic biomaterial filler, such as flour. Thus, the concentration of organic biomaterial filler (e.g., flour) is typically less than 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1% by weight of the total film composition.

[0063] In some embodiments, the first film layer includes an antiblocking agent, such as a fatty acid derivative. One suitable antiblocking agent is a mixture of PLA polymer, 5-10 wt. % fatty acid derivative, and 20-40 wt. % silica, such as that available under the trade name SUKANO DCS511 from Sukano Polymers Corporation (Duncan, SC).

[0064] The first film layer may optionally include one or more conventional additives, such as antioxidants, stabilizers, UV absorbers, lubricants, processing aids, antistatic agents, colorants, impact resistance aids, fillers (e.g., diatomaceous earth), matting agents, flame retardants (e.g., zinc borate), pigments (e.g., titanium dioxide), etc. Some examples of fillers or pigments include inorganic oxide materials such as zinc oxide, titanium dioxide, silica, carbon black, calcium carbonate, antimony trioxide, metal powders, mica, graphite, talc, ceramic microspheres, glass or polymer beads or bubbles, fibers, starch, etc.

[0065] When present, the amount of additive may be at least 0.1, 0.2, 0.3, 0.4, or 0.5 wt. %. In some embodiments, the amount of additive is no more than 25, 20, 15, 10, or 5 wt. % of the total film composition. In other embodiments, the concentration of additive may range no more than 40, 45, 50, 55, or about 65 wt. % of the total film composition.

[0066] In some embodiments, the first (e.g., printed) film layer (e.g., 101) comprises one or more inorganic pigments. Examples of suitable inorganic pigments include metal oxides (including mixed metal oxides), metal sulfides, and metal salts. Examples include titanium dioxide, zinc oxide, zinc sulfide, and antimony oxide. Preferred inorganic pigments are metal oxides. Various combinations of inorganic pigments may also be used.

[0067] In one embodiment, the inorganic pigment is titanium dioxide in finely divided form (e.g., rutile). Titanium dioxide can provide opacity for the white film layer as well as light scattering and UV absorption. Generally, the greater the difference between the refractive index of the pigment and the refractive index of the PLA-containing polymer matrix in which the pigment is dispersed, the greater the light scattering.

[0068] For most effective light scattering, pigment particle size is typically slightly smaller than half the wavelength of the light being scattered. Because the eye is most sensitive to yellow-green light (approximately 0.55 μm wavelength), commercially available TiO pigments for plastics typically have a median particle size in the 0.2-0.4 μm diameter range. The light scattering achieved by diffraction is affected by particle spacing and average pigment particle size. If the particles are too large or too closely spaced, little diffraction occurs. If the pigment particles are too small, the light never "sees" them.

[0069] Titanium dioxide (e.g., rutile) is an efficient UV protectant for plastic applications because it strongly absorbs radiation below 380 nm. In the presence of water and oxygen, rutile titanium dioxide can act as a photocatalytic agent. In some embodiments, titanium dioxide pigments are surface coated with silica or other metal oxides to minimize this photocatalytic ability. In some embodiments, the titanium dioxide pigments contain at least 1, 1.5, 2, 2.5, or 3 wt.% silica. The silica content of titanium dioxide pigments is typically no greater than 10, 9.5, 9, 8.5, 8, 7.5, 7, or 6.5 wt.%. In some embodiments, the titanium dioxide pigments include an alumina surface treatment. In some embodiments, the titanium dioxide pigments contain at least 0.5, 1, or 1.5 wt.% alumina. The alumina content of titanium dioxide pigments is typically no greater than 10, 9.5, 9, 8.5, 8, 7.5, 7, 6.5, 6, 5.5, 4.5, or 4 wt.%. In some embodiments, the titanium dioxide pigment includes an organic (eg, hydrophobic) surface treatment.

[0070] Various pigments are commercially available, such as titanium dioxide available from Chemours Company under the tradenames Ti-Pure R-101, R-103, R-104, R-105, R-350, and R-960.

[0071] In some embodiments, the pigment may be pre-blended with a semi-crystalline or amorphous polylactic acid polymer, such as in the case of CLARIANT PLA 4060D TiO2MB and CLARIANT PLA 4032D TiO2MB, manufactured by CLARIANT.

[0072] In some embodiments, the amount of inorganic pigment (e.g., TiO2) is at least 1, 2, 3, 4, 5, 6, 7, 8, 9, 10% by weight of the first PLA-containing film layer. In some embodiments, the amount of inorganic pigment (e.g., TiO2) is at least 11, 12, 13, 14, 15, 16, 17, 18, 19, 20% by weight of the first PLA-containing film layer. The amount of inorganic pigment (e.g., TiO2) is typically no more than 50, 45, 40, 35, or 30% by weight of the first PLA-containing film layer.

[0073] The ratio of total (e.g., semi-crystalline and amorphous) polylactic acid polymer to total (e.g., TiO) inorganic pigment can vary. In some embodiments, the first film layer containing PLA contains a relatively large amount of total (e.g., semi-crystalline and amorphous) polylactic acid polymer compared to the total amount of inorganic pigment (e.g., TiO). For example, if the first film layer containing PLA contains 50% by weight polylactic acid polymer and 2% by weight inorganic pigment (e.g., TiO), the ratio is 50 / 2, or in other words, 25:1. As the total amount of inorganic pigment (e.g., TiO) increases, the ratio decreases. In some embodiments, the ratio of total (e.g., semi-crystalline and amorphous) polylactic acid polymer to total inorganic pigment (e.g., TiO) is less than 20:1, 15:1, or 10:1. In some embodiments, the ratio of total (e.g., semi-crystalline and amorphous) polylactic acid polymer to total (e.g., TiO) inorganic pigment is less than 9:1, 8:1, 7:1, 6:1, or 5:1. For example, if the first film layer comprises 54.4 wt. % polylactic acid polymer and 11.3 wt. % (e.g., TiO) inorganic pigment, the ratio is 54.4 / 11.3, or in other words, 4.8 / 1.

[0074] At even higher concentrations of inorganic pigment (e.g., TiO), the ratio decreases further. In some embodiments, the ratio of total (e.g., semi-crystalline and amorphous) polylactic acid polymer to total (e.g., TiO) inorganic pigment is less than 4.5:1, 4.4:1, 4.3:1, 4.2:1, 4.1:1, 4:1, 3.9:1, 3.8:1, 3.7:1, 3.6:1, 3.5:1, 3.4:1, 3.3:1, 3.2:1, 3.1:1, or 3:1. In some embodiments, the ratio is at least 1:1, 1.5:1, or 2:1. Surprisingly, high elongation can be obtained at high loadings of inorganic pigment (e.g., TiO).

[0075] In one embodiment, the PLA-containing film layer includes one or more hydrolysis stabilizers, also known as hydrolysis inhibitors. In some embodiments, the first film layer (e.g., 101) includes one or more hydrolysis stabilizers. In some embodiments, the PLA-containing cover film (e.g., 401) includes one or more hydrolysis stabilizers. In yet other embodiments, both the first film layer and the PLA-containing cover film include one or more hydrolysis stabilizers.

[0076] In some embodiments, the hydrolytic stabilizer is a carbodiimide hydrolytic stabilizer, ie, a compound or polymer that contains one or more carbodiimide groups.

[0077] Compounds containing carbodiimide groups are described, for example, in U.S. Patent Nos. 5,210,170 and 5,614,483, and U.S. Patent Application Publication No. 2010 / 0093888(A1), which are incorporated herein by reference. Polymeric materials containing carbodiimide groups are described, for example, in U.S. Patent No. 6,498,225, which is incorporated herein by reference.

[0078] Examples of the carbodiimide-containing compound include mono- and dicarbodiimide compounds, such as dicyclohexylcarbodiimide, diisopropylcarbodiimide, dimethylcarbodiimide, diisobutylcarbodiimide, dioctylcarbodiimide, octyldecylcarbodiimide, di-t-butylcarbodiimide, t-butylisopropylcarbodiimide, dibenzylcarbodiimide, diphenylcarbodiimide, N-octadecyl-N'-phenylcarbodiimide, N-benzyl-N'-phenylcarbodiimide, and N-benzyl-N'-phenylcarbodiimide. '-Tolylcarbodiimide, di-o-toluoylcarbodiimide, di-p-toluoylcarbodiimide, bis(p-nitrophenyl)carbodiimide, bis(p-aminophenyl)carbodiimide, bis(p-hydroxyphenyl)carbodiimide, bis(p-chlorophenyl)carbodiimide, bis(o-chlorophenyl)carbodiimide, bis(o-ethylphenyl)carbodiimide, bis(p-ethylphenyl)carbodiimide, bis(o-isopropylphenyl)carbodiimide, bis(p-isopropylphenyl)carbodiimide Imide, bis(o-isobutylphenyl)carbodiimide, bis(p-isobutylphenyl)carbodiimide, bis(2,5-dichlorophenyl)carbodiimide, p-phenylenebis(o-toluoylcarbodiimide), p-phenylenebis(cyclohexylcarbodiimide), p-phenylenebis(p-chlorophenylcarbodiimide), 2,6,2',6'-tetraisopropyldiphenylcarbodiimide, hexamethylenebis(cyclohexylcarbodiimide), ethylenebis(phenylcarbodiimide), ethylenebis(cyclo cyclohexylcarbodiimide), bis(2,6-dimethylphenyl)carbodiimide, bis(2,6-diethylphenyl)carbodiimide, bis(2-ethyl-6-isopropylphenyl)carbodiimide, bis(2-butyl-6-isopropylphenyl)carbodiimide, bis(2,6-diisopropylphenyl)carbodiimide, bis(2,6-di-t-butylphenyl)carbodiimide, bis(2,4,6-trimethylphenyl)carbodiimide, bis(2,4,6-triisopropylphenyl)carbodiimide, bis(2,4,6-tributylphenyl)carbodiimide, di-β-naphthylcarbodiimide, N-tolyl-N'-cyclohexylcarbodiimide, and N-tolyl-N'-phenylcarbodiimide.

[0079] Examples of polycarbodiimides include poly(1,6-cyclohexanecarbodiimide), poly(4,4'-methylenebiscyclohexylcarbodiimide), poly(1,3-cyclohexylenecarbodiimide), poly(1,4-cyclohexylenecarbodiimide), poly(4,4'-diphenylmethanecarbodiimide), poly(3,3'-dimethyl-4,4'-diphenylmethanecarbodiimide), poly(naphthylenecarbodiimide), poly(p-phenylenecarbodiimide), poly(m-phenylenedicarbodiimide), poly(p-tolylcarbodiimide), poly(diisopropylcarbodiimide), poly(methyldiisopropylphenylenecarbodiimide), and poly(triethylphenylenecarbodiimide). Commercially available polycarbodiimide compounds include CARBODILITE LA-1, HMV-5CA, and HMV-15CA (trade names of CARBODILITE) available from Nisshinbo.

[0080] In some embodiments, the hydrolysis stabilizer is bis(2,6-diisopropylphenyl)carbodiimide, available from a variety of suppliers, as shown below. [ka]

[0081] The hydrolysis stabilizer may optionally contain small amounts (eg, less than 2%) of 2,6-diisopropylphenyl isocyanate (DIPI).

[0082] In one embodiment, the PLA-containing first (e.g., printed) film layer and / or the PLA-containing (e.g., printed or unprinted) cover film contain one or more commercially available carbodiimide hydrolysis inhibitors. One example of such a material is available under the trade name STABAXOL I, which is a monomeric carbodiimide manufactured by Rhein Chemie (Chardon, Ohio). Other carbodiimide-containing compounds include those available under the trade names STABAXOL I LF (which is a monomeric compound containing carbodiimide groups) and STABAXOL P (which is a polymeric material containing carbodiimide groups), both manufactured by Rhein Chemie. Another example of a hydrolysis stabilizer containing carbodiimide groups is available as "CARBODILITE HMV-15CA" from Nisshinbo Chemical.

[0083] In some embodiments, the (e.g., carbodiimide) hydrolysis inhibitor has a softening point of at least 60, 65, or 70°C. In other embodiments, the (e.g., carbodiimide) hydrolysis inhibitor has a softening point of less than 60°C. For example, the softening point may be in the range of about 45-55°C. In some embodiments, the (e.g., carbodiimide) hydrolysis inhibitor has a weight loss of less than 5% at 300°C. In other embodiments, the (e.g., carbodiimide) hydrolysis inhibitor has a weight loss of less than 4, 3, 2, or 1% at 300°C.

[0084] Various combinations of the hydrolysis stabilizers described herein (eg, carbodiimides) can be used in the first film layer containing PLA.

[0085] In some embodiments, the amount of hydrolysis stabilizer (e.g., carbodiimide) is at least 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.0 wt.% of the PLA-containing first film layer and / or cover film. In some embodiments, the amount of hydrolysis stabilizer (e.g., carbodiimide) is at least 1.5, 2, 2.5, 3.0, 3.5, 4.0, 4.5, or 5 wt.% of the PLA-containing first film layer and / or cover film. In some embodiments, the amount of hydrolysis stabilizer (e.g., carbodiimide) is no more than 10, 9, 8, 7, 6, 5, 4, or 3 wt.% of the PLA-containing first film layer and / or cover film.

[0086] The color stability of the printing ink can be improved by including a (e.g., carbodiimide) hydrolysis stabilizer and / or an inorganic (e.g., TiO) pigment. The color change of a printed PLA-based film before and after accelerated aging can be determined according to the test methods described in the Examples. In some embodiments, the printed PLA-based film exhibits a color change of 0.1, 0.2, 0.3, 0.4, or 0.5 or less in the white and / or black ink after exposure to a total irradiation dose of 179, 357, 539, 717, 901, or 1082 MJ / m. In some embodiments, the printed PLA-based film exhibits a color change of 0.2, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 or less in the cyan and / or yellow ink after exposure to a total irradiation dose of 179, 357, 539, 717, 901, or 1082 MJ / m. In some embodiments, the printed PLA-based film exhibits a color change of no more than 4, 5, 6, 7, 8, 9, or 10 magenta ink after exposure to a total dose of 179, 357, 539, 717, 901, or 1082 MJ / m2.

[0087] The inclusion of (e.g., carbodiimide) hydrolysis stabilizers and inorganic (e.g., TiO2) pigments can improve the molecular weight stability of PLA-based compositions. Tables 13-15 report the molecular weights of various PLA-based film compositions as measured by gel permeation chromatography (as further described in the Examples).

[0088] In the absence of a (e.g., carbodiimide) hydrolysis stabilizer, a PLA-based film composition (e.g., containing inorganic pigments) exhibits a hydrolysis of 360 MJ / m 2 After a total exposure of 38%, 720MJ / m 2 After a total exposure of 46%, 1080MJ / m 2 However, when the PLA-based film composition includes a (e.g., carbodiimide) hydrolysis stabilizer, the molecular weight loss is substantially less than the same film composition without the hydrolysis stabilizer. For example, in some embodiments, a PLA-based film composition including a (e.g., carbodiimide) hydrolysis stabilizer can exhibit a 57% weight average molecular weight (Mw) loss after a total exposure of 360 MJ / m 2 In some embodiments, PLA-based film compositions containing a (e.g., carbodiimide) hydrolysis stabilizer exhibit a reduction in weight average molecular weight (Mw) of less than 35%, 30%, 25%, 20%, 15%, and 10% after a total exposure of 720 MJ / m 2 Furthermore, in some embodiments, PLA-based film compositions containing a (e.g., carbodiimide) hydrolysis stabilizer exhibit a weight average molecular weight (Mw) reduction of less than 50%, 45%, 40%, 35%, 30%, and 25% after a total exposure of 1080 MJ / m 2 exhibiting a weight average molecular weight (Mw) reduction of less than 55%, 50%, 45%, 40%, 35%, 30% and 25% after a total exposure of

[0089] In the absence of a (e.g., carbodiimide) hydrolysis stabilizer, a PLA-based film composition (e.g., containing inorganic pigments) exhibits a hydrolysis of 360 MJ / m 2 After a total exposure of 50%, 720MJ / m 2 After a total exposure of 67%, 1080MJ / m 2 After a total exposure of 360 MJ / m, the PLA-based film composition may exhibit a 78% decrease in number average molecular weight (Mn). However, when the PLA-based film composition includes a (e.g., carbodiimide) hydrolysis stabilizer, the molecular weight decrease is substantially less than the same film composition without the hydrolysis stabilizer. For example, in some embodiments, a PLA-based film composition including a (e.g., carbodiimide) hydrolysis stabilizer exhibits a 360 MJ / m2 In some embodiments, PLA-based film compositions containing a (e.g., carbodiimide) hydrolysis stabilizer exhibit a number average molecular weight (Mn) decrease of less than 45%, 40%, 35%, 30%, 25%, 20%, and 15% after a total exposure of 720 MJ / m 2 Furthermore, in some embodiments, PLA-based film compositions containing a (e.g., carbodiimide) hydrolysis stabilizer exhibit a reduction in number average molecular weight (Mw) of less than 55%, 50%, 45%, 40%, 35%, 30%, and 25% after a total exposure of 1080 MJ / m 2 exhibiting a decrease in number average molecular weight (Mn) of less than 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40% and 35% after a total exposure of

[0090] In the absence of a (e.g., carbodiimide) hydrolysis stabilizer, a PLA-based film composition (e.g., containing inorganic pigments) exhibits a hydrolysis of 360 MJ / m 2 After a total exposure of 60%, 720MJ / m 2 After a total exposure of 79%, 1080MJ / m 2 After a total exposure of 360 MJ / m, the PLA-based film composition may exhibit an 85% reduction in peak molecular weight (Mp). However, when the PLA-based film composition includes a (e.g., carbodiimide) hydrolysis stabilizer, the reduction in peak molecular weight is substantially less than the same film composition without the hydrolysis stabilizer. For example, in some embodiments, a PLA-based film composition including a (e.g., carbodiimide) hydrolysis stabilizer exhibits a peak molecular weight reduction of 360 MJ / m. 2 In some embodiments, PLA-based film compositions containing a (e.g., carbodiimide) hydrolysis stabilizer exhibit a peak molecular weight (Mp) decrease of less than 40%, 35%, 30%, 25%, 20%, and 15% after a total exposure of 720 MJ / m 2 Furthermore, in some embodiments, PLA-based film compositions containing a (e.g., carbodiimide) hydrolysis stabilizer exhibit a peak molecular weight (Mp) reduction of less than 55%, 50%, 45%, 40%, 35%, 30%, and 25% after a total exposure of 1080 MJ / m 2 exhibiting peak molecular weight (Mp) reductions of less than 75%, 70%, 65%, 60%, 55%, 50%, 45%, 40% and 35% after a total exposure of

[0091] The first PLA-based film described herein can be a monolithic film or a film layer of a multilayer film. The first PLA-based film or film layer is typically not oriented, but can optionally be oriented.

[0092] When the film is a monolithic film, the thickness of the film is typically at least 10, 15, 20, or 25 microns (1 mil) to 500 microns (20 mils) thick. In some embodiments, the thickness of the film is 2500, 2000, 1500, 1000, 800, 400, 300, 200, 150, or 50 microns or less. The film may be in sheet form, particularly at thicknesses greater than 50 mils. (Thinner) films, for example, may be in roll-good form.

[0093] When the film is a film layer of a multilayer film, the multilayer film typically has a thickness as described above. However, the thickness of the film layer may be less than 10 microns. In one embodiment, the film layer comprising the film composition described herein is the outer layer, or in other words, the skin layer. A second film layer is disposed on the skin layer. The second film layer typically has a different composition from the skin layer. In some embodiments, the second film is a PLA-based film having a different composition from the first film layer.

[0094] In preparing the first film composition described herein, the second polymer, such as PLA or PVAc, the plasticizer, the nucleating agent, etc., are heated (e.g., 180-250°C) and thoroughly mixed using any suitable means known to those skilled in the art. For example, the film composition may be mixed using a mixer (e.g., a Brabender), an extruder, a kneader, etc.

[0095] After mixing, the film composition may be formed (e.g., cast) into a film using known film-forming techniques, taking into account the scale of the process and available equipment. In some embodiments, the PLA-based film composition is fed into a press, then compressed and solidified to form a sheet of PLA film. In other embodiments, the PLA-based film composition can be extruded through a die onto a casting roll maintained at a suitable cooling temperature to form a continuous length of PLA-based film. In some embodiments, the casting roll temperature is preferably maintained at 80-120°C during film extrusion to obtain a crystalline PLA film on the casting roll.

[0096] The PLA-based films described herein can be used in a variety of (e.g., graphic) articles. In some embodiments, PLA films have properties similar to or even better than polyvinyl chloride (PVC) films and can therefore be used in place of PVC films. Thus, the films and articles described herein may be free of polyvinyl chloride (PVC) films or phthalate-based plasticizers.

[0097] The films and film compositions can have a variety of properties as determined by the test methods described in the examples.

[0098] The first PLA-based film composition generally has a glass transition temperature of about -20°C, -15°C, or in the range of -10°C to 40°C, i.e., below the Tg of both the PLA polymer and the second (e.g., polyvinyl acetate) polymer. In some embodiments, the film has a glass transition temperature of at least -5, -4, -3, -2, -1, or 0°C. In some embodiments, the film has a glass transition temperature of less than 35°C, or 30°C, or 25°C. In some embodiments, the film has a glass transition temperature of less than 20°C, 19°C, 18°C, 17°C, or 16°C.

[0099] The first PLA-based film typically has a melting point T in the range of at least about 120, 130, 140, 150°C, or 155°C to about 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 200°C, or 210°C. m1 or T m2 The melting point is typically a single peak or can be the average of (e.g., two) peaks. Additionally, the film composition has a crystallization peak temperature T in the range of 50°C, 60°C, 70°C, 80°C, 90°C, or 100°C up to 120°C, 130°C, or 140°C. c may have:

[0100] The net melting endotherm is the melting endotherm energy minus the crystallization exotherm energy (as described in more detail in the Examples below). The net melting endotherm of a film composition (i.e., taken from a mini-kneader, not melt-pressed into a film) is determined by a second heating scan, while the net melting endotherm of a film (e.g., melt-pressed or extruded) is determined by a first heating scan. In some embodiments, the net melting enthalpy ΔH of the film is nm1 is greater than or equal to 0, and even less than 10 J / g. The film may have a low net melting endotherm due to the film composition containing little or no semi-crystalline PLA. Alternatively, a film containing a substantial amount of semi-crystalline PLA may have a low net melting endotherm because it is unannealed. In some embodiments, the net melting enthalpy ΔH of the film nm1 is less than 9, 8, 7, 6, 5, 4, 3, 2, or 1 J / g. In other embodiments, the net enthalpy of melting of the film, ΔH nm2 and ΔH nm1 are greater than 10, 11, 12, 13, 14 or 15 J / g and less than 40, 39, 38, 37, 36 or 35 J / g, respectively.

[0101] In one embodiment, the first PLA-based film has a Tg of -10 to 30°C, or 35°C, or 40°C, and a net endotherm of melting ΔH of greater than 10 J / g and less than 40 J / g, as previously described. nm1Such films are flexible at room temperature and have relatively high mechanical properties, such as modulus, when heated to elevated temperatures, as shown by the dynamic mechanical analysis (DMA) results in FIG. 11 . In this embodiment, the film has a tensile storage modulus of at least 10 MPa, and typically less than 10,000 MPa, when heated at a rate of 2°C / min in the temperature range of -40°C to 125°C (i.e., when heated at a rate of 2°C / min from -40°C to 125°C, the tensile storage modulus does not decrease below 10 MPa). In some embodiments, the film has a tensile storage modulus, as determined by dynamic mechanical analysis, of at least 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 MPa when heated at a rate of 2°C / min in the temperature range of 25°C to 80°C. In contrast, as shown in FIG. 12 , when a film has a very low net melting endotherm, a dramatic decrease in mechanical properties, such as modulus, occurs when the temperature is increased above room temperature, 23°C. However, as evidenced by comparing Example 12 (which has a net melting endotherm of 27 J / g) with Example 16 (which has a net melting endotherm of 1.7), films with lower net melting endotherms can have higher tensile strength, higher modulus, and higher elongation.

[0102] Thermal properties (e.g., Tg, Tm, net melting endotherm) can be determined by the DSC test method described in the Examples. Such tests can be performed on bulk compositions or films. However, Tg refers to the composition since the thermal history is erased.

[0103] The first heating scan was used to determine the melting temperature (Tm) and the net melting endotherm ΔH nm1 When the composition contains sufficient amounts of semi-crystalline PLA and nucleating agent, and the film is annealed, the net melting endotherm of the film, ΔH nm1 is typically 10 J / g or greater. However, if the composition has little or no semicrystalline PLA, lacks a nucleating agent, and / or the film is unannealed (i.e., unannealed), the net melting endotherm of the film, ΔH nm1is typically less than 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 J / g. If the composition contains sufficient amounts of semi-crystalline PLA and nucleating agent to cause a low net melting endotherm in an unannealed film, the film can be (e.g., post-) annealed to increase the net melting endotherm. Such annealing can occur one day, one month, three months, six months, and even one, two, three, four, or five years after the unannealed film is produced. In some cases, post-annealing increases the net melting endotherm to 10 J / g or more. In other examples, the net melting endotherm after post-annealing is 0, or less than 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 J / g.

[0104] The first PLA-based film can be evaluated using a standard tensile test (e.g., using a rate of 1 inch (2.5 cm) / minute (100% strain / minute) or 6 inches (15.2 cm) / minute (600% strain / minute)), as further described in the Examples below. The tensile strength of the film is typically at least 5 or 10 MPa and is typically less than the tensile strength of the PLA and second (e.g., polyvinyl acetate) polymer utilized to make the film. In some embodiments, the tensile strength is 45, 44, 43, 42, 41, 40, 39, 38, 37, 36, 35, 34, 33, 32, 31, or 30 MPa or less. In some embodiments, the tensile strength is at least 15, 16, 17, 18, 19, or 20 MPa. The elongation of the film is typically greater than the elongation of the PLA and second (e.g., polyvinyl acetate) polymer utilized to make the film. In some embodiments, the elongation is at least 30, 40, or 50%. In other embodiments, the elongation is at least 100%, 125%, 150%, 175%, 200%, 225%, 250%, 275%, or 300%. In some embodiments, the elongation is no greater than 650%, 600%, 550%, 500%, 450%, or 400%. In some embodiments, the elongation is no greater than 375%, 350%, 300%, 275%, or 250%. The tensile modulus of the film is typically at least 1, 5, 10, 50, 100, or 150 MPa. In some embodiments, the tensile modulus is at least 200, 250, 300, 350, 400, 450, 500, or 550 MPa. In some embodiments, the tensile modulus is less than or equal to 1500 MPa, 1400 MPa, 1300 MPa, 1200 MPa, 1100 MPa, 1000 MPa, 750 MPa, 650 MPa, 600 MPa, 550 MPa, 500 MPa, 450 MPa, or 400 MPa.

[0105] In some embodiments, the first PLA-based film layer is transparent and has a visible light transmittance of at least 90 percent. If the first film layer is transparent, it can be used for any layer within the film, such as a backing, a cover film, or an intermediate layer (i.e., a layer between the outermost layers). In other embodiments, the first PLA-based film layer is opaque (e.g., white) or reflective, and is typically used as a backing or intermediate layer.

[0106] The film may optionally include a second (e.g., film) layer adjacent to the first film layer. In a typical embodiment, the second layer is different from the first film layer. If the second layer is transparent and has a visible light transmittance of at least 90 percent, it can be utilized as any layer of the (e.g., graphic) article, such as a backing, cover film, or intermediate layer. If the second (e.g., film) layer is opaque (e.g., white) or reflective, it is typically used as a backing or intermediate layer. The (e.g., graphic) film may include multiple second layers. In one embodiment, the PLA-based film described herein is utilized as a backing and cover film with a graphic disposed between the backing and cover film.

[0107] The second layer may be in contact with the first film layer, or a primer or adhesion-promoting treatment may be disposed between the first film layer and the second (e.g., film). In some embodiments, a layer of adhesive composition is adjacent to the first PLA-based film layer or the second (e.g., film) layer. The adhesive is typically disposed directly on the first film layer or the second layer. Alternatively, a primer or adhesion-promoting treatment may be applied between the first film layer or the second layer and the adhesive layer.

[0108] The (e.g., graphic) article may be a tape or sheet that further comprises a (e.g., pressure-sensitive) adhesive. For example, a PLA-based film 101 can be characterized as a backing film (as shown in FIG. 1) that includes a graphic 110 disposed on one major surface and a (e.g., pressure-sensitive) adhesive disposed on the opposing major surface 106 of the backing. The pressure-sensitive adhesive typically further comprises a removable release liner.

[0109] In another embodiment, a sufficiently transparent layer of adhesive composition may be disposed between a first film layer and a second (e.g., film) layer. The first film layer may be a backing, a cover film, or both a backing and a cover film. The graphic is typically positioned under the cover film, or under the adhesive and the cover film. Thus, the graphic is visible through the cover film and, optionally, through the adhesive.

[0110] PLA-based films may be subjected to conventional surface treatments to improve adhesion to adjacent pressure-sensitive adhesive layers. Surface treatments include, for example, exposure to ozone, flame, high-voltage shock, ionizing radiation, and other chemical or physical oxidation treatments. Chemical surface treatments include primers. Examples of suitable primers include chlorinated polyolefins, polyamides, modified polymers disclosed in U.S. Pat. Nos. 5,677,376 and 5,623,010, as well as those disclosed in WO 98 / 15601 and WO 99 / 03907, and other modified acrylic polymers. In one embodiment, the primer is an organic solvent-based primer containing an acrylate polymer, a chlorinated polyolefin, and an epoxy resin, available from 3M Company as "3M® Primer 94."

[0111] Various (e.g., pressure-sensitive) adhesives can be applied to PLA-based films, such as natural or synthetic rubber-based pressure-sensitive adhesives, acrylic pressure-sensitive adhesives, vinyl alkyl ether pressure-sensitive adhesives, silicone pressure-sensitive adhesives, polyester pressure-sensitive adhesives, polyamide pressure-sensitive adhesives, polyα-olefins, polyurethane pressure-sensitive adhesives, and styrene block copolymer-based pressure-sensitive adhesives. Pressure-sensitive adhesives generally have a viscosity of 3×10 at a frequency of 1 Hz, which can be measured by dynamic mechanical analysis at room temperature (25° C.). 6 It has a storage modulus (E') of less than dynes / cm.

[0112] In some embodiments, the pressure-sensitive adhesive may be natural rubber-based, meaning that the natural rubber elastomer constitutes at least about 20% by weight of the adhesive's elastomer component (without any fillers, tackifiers, etc.). In further embodiments, the natural rubber elastomer constitutes at least about 50% by weight, or at least about 80% by weight, of the adhesive's elastomer component. In some embodiments, the natural rubber elastomer may be blended with one or more block copolymer thermoplastic elastomers (e.g., the general type available under the trade name KRATON from Kraton Polymers, Houston, TX). In certain embodiments, the natural rubber elastomer may be blended with a styrene-isoprene radical block copolymer in combination with the natural rubber elastomer, along with at least one tackifying resin. Adhesive compositions of this type are disclosed in further detail in U.S. Patent Application Publication No. 2003 / 0215628 (Ma et al.), incorporated by reference.

[0113] Pressure-sensitive adhesives may be organic solvent-based, water-based emulsion, hot melt (such as those described in U.S. Pat. No. 6,294,249), heat-sensitive, and actinic radiation (e.g., electron beam, ultraviolet) curable pressure-sensitive adhesives. Heat-sensitive adhesives can be prepared from the same categories as those described above for pressure-sensitive adhesives. However, the ingredients and concentrations are selected such that the adhesive is heat-sensitive rather than pressure-sensitive, or a combination thereof.

[0114] In some embodiments, the adhesive layer is a repositionable adhesive layer. The term "repositionable" refers to the ability to be repeatedly adhered to and removed from a substrate without, at least initially, substantial loss of adhesive capacity. Repositionable adhesives typically have a peel strength from the substrate surface that is, at least initially, lower than the peel strength of conventional strong-tack PSAs. Suitable repositionable adhesives include the types of adhesives used in CONTROLTAC Plus Film and SCOTCHLITE Plus Sheeting brands, both manufactured by Minnesota Mining and Manufacturing Company (St. Paul, Minnesota, USA).

[0115] The adhesive layer can also have a structured adhesive layer or an adhesive layer with at least one microstructured surface.When a film article comprising such a structured adhesive layer is applied to a substrate surface, a network of channels or similar structures exists between the film article and the substrate surface.The presence of such channels or similar structures allows air to pass horizontally through the adhesive layer, thereby allowing air to escape from under the film article and the surface substrate during application.

[0116] Topologically structured adhesives can also be used to provide repositionable adhesives. For example, it has been described that relatively large-scale adhesive embossing permanently reduces the pressure-sensitive adhesive / substrate contact area, thereby reducing the adhesive strength of the pressure-sensitive adhesive. Various topologies include concave and convex V-grooves, diamonds, cups, hemispheres, cones, craters, and other three-dimensional shapes, all of which have an upper surface significantly smaller than the lower surface of the adhesive layer. Generally, these topologies provide adhesive sheets, films, and tapes with lower peel adhesion values than adhesive layers with smooth surfaces. In many cases, adhesives with this topologically structured surface have also been shown to build up adhesion more slowly with increasing contact time.

[0117] Adhesive layers with microstructured adhesive surfaces can include adhesive or composite adhesive "pegs" uniformly distributed throughout the functional portions of the adhesive surface and projecting outward from the adhesive surface. Film articles with such adhesive layers provide repositionable sheet materials when placed on a substrate surface (see U.S. Pat. No. 5,296,277). Such adhesive layers also require a matching microstructured release liner to protect the adhesive pegs during storage and processing. Forming a microstructured adhesive surface can also be achieved, for example, by coating the adhesive onto a release liner with a corresponding micro-embossed pattern, or by pressing the adhesive (e.g., PSA) against a release liner with a corresponding micro-embossed pattern, as described in WO 98 / 29516.

[0118] If desired, the adhesive layer may include multiple adhesive sub-layers to provide a combined adhesive layer assembly, for example, the adhesive layer may include a sub-layer of hot melt adhesive along with a continuous or discontinuous PSA or repositionable adhesive coating layer.

[0119] Acrylic pressure-sensitive adhesives can be produced by free radical polymerization techniques such as solution polymerization, bulk polymerization, or emulsion polymerization. The acrylic polymer can be of any type, such as a random copolymer, a block copolymer, or a graft polymer. The polymerization can be carried out using any of the commonly used polymerization initiators and chain transfer agents.

[0120] The acrylic pressure sensitive adhesives include polymerized units of one or more (meth)acrylate ester monomers derived from (e.g., non-tertiary) alcohols containing from 1 to 14 carbon atoms, preferably an average of 4 to 12 carbon atoms. Examples of monomers include esters of non-tertiary alcohols such as ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-pentanol, 2-pentanol, 3-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 1-hexanol, 2-hexanol, 2-methyl-1-pentanol, 3-methyl-1-pentanol, 2-ethyl-1-butanol; 3,5,5-trimethyl-1-hexanol, 3-heptanol, 1-octanol, 2-octanol, isooctyl alcohol, 2-ethyl-1-hexanol, 1-decanol, 2-propylheptanol, 1-dodecanol, 1-tridecanol, 1-tetradecanol, and the like, with either acrylic or methacrylic acid.

[0121] The acrylic pressure sensitive adhesive comprises polymerized units of one or more low Tg (meth)acrylate monomers, i.e., the (meth)acrylate monomers when reacted to form a homopolymer have a T of 0° C. or less. g In some embodiments, the low Tg monomer has a T of -5°C or less, or -10°C or less. g The Tg of these homopolymers is often −80° C. or higher, −70° C. or higher, −60° C. or higher, or −50° C. or higher.

[0122] The low Tg monomer may have the formula: H2C=CR 1 C(O)OR 8 [In the formula, R 1 is H or methyl, and R 8 is an alkyl having 1 to 22 carbons or a heteroalkyl having 2 to 20 carbons and 1 to 6 heteroatoms selected from oxygen or sulfur. The alkyl or heteroalkyl group can be linear, branched, cyclic, or a combination thereof.

[0123] Exemplary low Tg monomers include, for example, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, n-pentyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-methylbutyl acrylate, 2-ethylhexyl acrylate, 4-methyl-2-pentyl acrylate, n-octyl acrylate, 2-octyl acrylate, isooctyl acrylate, isononyl acrylate, decyl acrylate, isodecyl acrylate, lauryl acrylate, isotridecyl acrylate, octadecyl acrylate, and dodecyl acrylate.

[0124] Low Tg heteroalkyl acrylate monomers include, but are not limited to, 2-methoxyethyl acrylate and 2-ethoxyethyl acrylate.

[0125] In a typical embodiment, the acrylic pressure-sensitive adhesive comprises polymerized units of at least one low Tg monomer having an alkyl group containing 6 to 20 carbon atoms. In some embodiments, the low Tg monomer has an alkyl group containing 7 or 8 carbon atoms. Exemplary monomers include, but are not limited to, esters of (meth)acrylic acid with alcohols derived from renewable resources, such as 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, and 2-octyl (meth)acrylate.

[0126] Acrylic pressure-sensitive adhesives typically include at least 50, 55, 60, 65, 70, 75, 80, 85, 90, or more by weight, based on the total weight of polymerized units (i.e., excluding inorganic fillers or other additives), of polymerized units of a monofunctional alkyl (meth)acrylate monomer having a Tg less than 0°C.

[0127] The acrylic pressure-sensitive adhesive may further comprise at least one high Tg monomer, i.e., the (meth)acrylate monomer when reacted to form the homopolymer has a Tg greater than 0° C. High Tg monomers more typically have a Tg greater than 5° C., 10° C., 15° C., 20° C., 25° C., 30° C., 35° C., or 40° C. High Tg monofunctional alkyl (meth)acrylate monomers include, for example, t-butyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, s-butyl methacrylate, t-butyl methacrylate, stearyl methacrylate, phenyl methacrylate, cyclohexyl methacrylate, isobornyl acrylate, isobornyl methacrylate, norbornyl (meth)acrylate, benzyl methacrylate, 3,3,5-trimethylcyclohexyl acrylate, cyclohexyl acrylate, N-octylacrylamide, and propyl methacrylate or combinations.

[0128] The acrylic pressure-sensitive adhesive may further comprise polymerized units of a polar monomer. Exemplary polar monomers include, for example, acid-functional monomers (e.g., acrylic acid, methacrylic acid), hydroxyl-functional (meth)acrylate monomers, nitrogen-containing monomers (e.g., acrylamide), and combinations thereof. In some embodiments, the acrylic pressure-sensitive adhesive comprises at least 0.5, 1, 2, or 3 weight percent, and typically no more than 10 weight percent, polymerized units of a polar monomer, such as acrylamide, and / or an acid-functional monomer, such as (meth)acrylic acid.

[0129] The pressure-sensitive adhesive may further contain one or more suitable additives, if necessary. Examples of the additives include crosslinkers (e.g., polyfunctional (meth)acrylate crosslinkers (e.g., TMPTA), epoxy crosslinkers, isocyanate crosslinkers, melamine crosslinkers, aziridine crosslinkers, etc.), tackifiers (e.g., phenol-modified terpenes and rosin esters such as glycerol esters of rosin and pentaerythritol esters of rosin, and C5 and C9 hydrocarbon tackifiers), thickeners, plasticizers, fillers, antioxidants, UV absorbers, antistatic agents, surfactants, leveling agents, colorants, flame retardants, and silane coupling agents.

[0130] The (e.g., pressure-sensitive) adhesive layer can be disposed on the film by a variety of conventional coating methods, including roller coating (e.g., gravure), flow coating, dip coating, spin coating, spray coating, knife coating, die coating (e.g., rotary or slit), extrusion coating (e.g., hot melt), and printing. The adhesive can be applied directly to the PLA film described herein or transfer coated using a release liner. When a release liner is used, the adhesive is either coated onto the liner and then laminated to the film, or coated onto the film with the release liner subsequently applied to the adhesive layer. The adhesive layer can be applied as a continuous layer or as a patterned, discontinuous layer. The adhesive layer typically has a thickness of about 5 to 50 μm.

[0131] Release liners typically comprise papers or films coated or modified with low surface energy compounds such as organosilicon compounds, fluoropolymers, polyurethanes, and polyolefins. The release liners may also be polymer sheets made from polyethylene, polypropylene, PVC, or polyester, with or without the addition of adhesive-repellent compounds. As mentioned above, the release liners may have a microstructured or microembossed pattern to impart structure to the adhesive layer.

[0132] In some embodiments, the sheet or tape (e.g., graphic) article comprises a low-adhesion backsize disposed on a first major exposed surface of the PLA-based film such that, when the sheet or tape is rolled, the outermost (exposed) surface of the pressure-sensitive adhesive contacts the low-adhesion backsize. In one embodiment, the PLA-based film is a cover film. In this embodiment, the graphic does not contact the low-adhesion backsize.

[0133] A variety of low adhesion backsize compositions have been described in the art, such as silicones, polyethylenes, polycarbamates, polyacrylics, and the like.

[0134] The composition of the low adhesion backsize (e.g., in combination with the pressure-sensitive adhesive composition) is selected to provide an appropriate level of release. In some embodiments, the low adhesion backsize can also enhance the ability to anchor paint placed thereon, as described in U.S. Patent Application Publication No. 2014 / 0138025.

[0135] Exemplary general classes of materials that may be suitable for inclusion in the low adhesion backsize include, for example, (meth)acrylic polymers, urethane polymers, vinyl ester polymers, vinyl carbamate polymers, fluorine-containing polymers, silicone-containing polymers, and combinations thereof.

[0136] In some embodiments, the low adhesion backsize is an organic solvent-based solution or an aqueous emulsion.

[0137] In some embodiments, the low-adhesion backsize may include an acrylic composition, which may be prepared from the same (meth)acrylate monomers as the acrylic adhesive. However, the low-adhesion backsize composition typically includes a low concentration of a low Tg monomer, such as octadecyl acrylate, and a higher concentration of a high Tg monomer, such as acrylic acid. In some embodiments, the low-adhesion backsize includes at least 40, 45, or 50 weight percent, up to about 60 weight percent, of polymerized units of the low Tg monomer, such as octadecyl acrylate. The weight percents for the low-adhesion backsizes described herein are based on total solids, excluding any organic or aqueous solvents, unless otherwise specified.

[0138] Such compositions are described in further detail in US Pat. No. 3,011,988 (Luedke et al.), which is incorporated by reference.

[0139] In some embodiments, a low adhesion backsize may have no discernible crystalline melting point (T m ) such T m is T g In some embodiments, T m (if present) may be in the range of, for example, 20°C to 60°C.

[0140] In some embodiments, the low adhesion backsize can include at least some (meth)acrylic acid groups, hi some embodiments, the concentration of (meth)acrylic acid groups ranges from at least 2, 3, 4, or 5 weight percent, up to and including 10, 15, or 20 weight percent.

[0141] In some embodiments, the low-adhesion backsize may include a silicone-containing material. In various embodiments, such materials may include a silicone backbone with non-silicone (e.g., (meth)acrylate) side chains, a non-silicone (e.g., (meth)acrylate) backbone with silicone side chains, a copolymer backbone including silicone units and non-silicone (e.g., (meth)acrylate) units, etc. Silicone polyurea materials, silicone polyurea polyurethane materials, silicone polyoxamide materials, siloxane iniferter-derived compositions, etc. may also be suitable.

[0142] In some embodiments, the silicone-containing material of the low adhesion backsize is a compound represented by Formula I [ka] The invention includes the reaction product of a vinyl functional silicone macromer having the general formula:

[0143] In some embodiments, the silicone-containing material of the low adhesion backsize has a formula IIa, IIb, or IIc [ka] or a mercapto-functional silicone macromer having the general formula:

[0144] Further details of mercapto-functional silicone macromers and the preparation of low adhesion backsize compositions using such macromers can be found in U.S. Pat. No. 5,032,460 (Kantner et al.), incorporated herein by reference.

[0145] In various embodiments, any of the silicone macromers described above can be used in combination with meth(acrylic) monomers and / or any other vinyl monomers. Such monomers can be used, for example, to achieve any of the glass transition temperature ranges described above. In some embodiments, the silicone macromer (e.g., of Formula IIa) can be used at about 15-35 wt.% of the total reactants, with the remainder of the reactants being at least one high T g (Meth)acrylic monomer, at least one low T g In certain embodiments, the low T g The monomer is methyl acrylate, which has high T g The monomer is methyl methacrylate and the (meth)acrylic acid monomer is methacrylic acid. In a further embodiment, in such compositions, the silicone macromer (e.g., of Formula IIa) is used at about 20-30 wt.%.

[0146] In some embodiments including silicone macromers, the low adhesion backsize comprises at least 2, 3, 4, or 5 weight percent, up to and including 10, 15, or 20 weight percent (meth)acrylic acid groups.

[0147] In some embodiments, the components of the pressure-sensitive adhesive and low-adhesion backsize (if present) are typically selected to provide good adhesion to the surface, but also to be removable with moderate force without leaving behind (e.g., visible) residue.

[0148] In some embodiments, the (e.g., graphic) articles described herein further include a second layer, which may be a backing disposed between the adhesive and the PLA-based film, and / or the second layer may be a transparent cover film disposed on the PLA-based backing film.

[0149] The backing can include a variety of flexible and non-flexible (e.g., preformed web) substrates, including, but not limited to, polymeric films, metal foils, foams, papers, and combinations thereof (e.g., metallized polymeric films). Polymeric films include, for example, polyolefins such as polypropylene (e.g., biaxially oriented), polyethylene (e.g., high or low density), polyvinyl chloride, polyurethane, polyester (polyethylene terephthalate), polycarbonate, polymethyl(meth)acrylate (PMMA), polyvinyl butyral, polyimides, polyamides, fluoropolymers, cellulose acetate, cellulose triacetate, ethyl cellulose, and bio-based materials such as polylactic acid (PLA).

[0150] In another embodiment, the first PLA-based film or backing can further comprise a metal or metal oxide layer. Examples of metals include aluminum, silicon, magnesium, palladium, zinc, tin, nickel, silver, copper, gold, indium, stainless steel, chromium, and titanium. Examples of metal oxides used in the metal oxide layer include aluminum oxide, zinc oxide, antimony oxide, indium oxide, calcium oxide, cadmium oxide, silver oxide, gold oxide, chromium oxide, silicon oxide, cobalt oxide, zirconium oxide, tin oxide, titanium oxide, iron oxide, copper oxide, nickel oxide, platinum oxide, palladium oxide, bismuth oxide, magnesium oxide, manganese oxide, molybdenum oxide, vanadium oxide, and barium oxide. These metals and metal oxides can be used alone or in combination of two or more. These metal and / or metal oxide layers can be formed by known methods such as vacuum deposition, ion plating, sputtering, and CVD (Chemical Vapor Deposition). The thickness of the metal and / or metal oxide layer is typically in the range of at least 5 nm, up to 100 or 250 nm.

[0151] The backing thickness is typically at least 10, 15, 20, or 25 microns (1 mil) thick, and typically no greater than 500 microns (20 mils). In some embodiments, the backing thickness is no greater than 400, 300, 200, or 100 microns. The first and second (e.g., film) layers may be the same thickness as the backing. However, the first and / or second (e.g., film) layers, particularly when used in combination with a backing, may be less than 10 microns. In some embodiments, the first and / or second film layers are typically at least 250 nm, 500 nm, 750 nm, or 1 micron thick. The backing and the film as a whole are typically in roll-good form, but may also be in sheet form.

[0152] In some embodiments, the second (e.g., film) layer is a thermoplastic polymer film such as polycarbonate, polyethylene terephthalate, polyamide, polyethylene, polypropylene, polystyrene, polyvinyl chloride, poly(meth)acrylic polymer, ABS (acrylonitrile-butadiene-styrene copolymer) resin, and the like.

[0153] In some embodiments, the entire film, the first film layer, the cover film, and / or the backing are conformable. By "conformable," it is meant that the film or film layer is soft and flexible enough to conform to curves, depressions, or protrusions on the substrate surface so that the film can be stretched around the curve or protrusion, or pressed down to create a depression without tearing or peeling. It is also desirable that the film does not peel or pop off from the substrate surface after application (known as pop-up).

[0154] Suitable conformable second film layers include, for example, polyvinyl chloride (PVC), plasticized polyvinyl chloride, polyurethane, polyethylene, polypropylene, fluoropolymers, etc. Other polymer blends are also optionally suitable, including, for example, thermoplastic polyurethanes and cellulose esters.

[0155] In some embodiments, the film is sufficiently conformable to be "laterally bendable," meaning that the tape can be bent into a continuous curved shape (e.g., a 7.5 cm radius of curvature) in a generally flat plane without tearing of the stretched area of the curved portion of the tape. An example of a laterally bendable tape is shown in Figure 15 of U.S. Patent Application Publication No. 2014 / 0138025.

[0156] Adhesive-coated (e.g., graphic) articles can exhibit good adhesion to both smooth and rough surfaces. Various rough surfaces are known, including textured drywall such as "knockdown" and "orange peel," cinderblock, rough (e.g., Brazilian) tile, and textured cement. Smooth surfaces, such as stainless steel, glass, and polypropylene, have an average surface roughness (Ra) of less than 100 nm, as measured by optical inferometry, whereas rough surfaces have an average surface roughness (Ra) of greater than 1 micron (1000 nm), 5 microns, or 10 microns. Sealing cements can have rough or smooth surfaces depending on the thickness of the waterstop. Cement waterstops typically contain polyurethane, epoxy resin, sodium silicate, or methyl methacrylate.

[0157] In some advantageous embodiments, the film is a graphic film used to apply designs, such as images, graphics, text, and / or information (such as codes), to windows, buildings, pavement, or vehicles (such as cars, vans, buses, trucks, trams, etc.), for example, advertising or decorative purposes. Such designs, images, text, etc. are collectively referred to herein as "graphics." Many surfaces (e.g., vehicles) are irregular and / or non-planar. In one embodiment, the graphic film is a decorative tape.

[0158] In some embodiments, the article is a floor marking graphic film tape that is typically adhered to (eg, seal) cement or other flooring surfaces.

[0159] Methods for producing a (e.g., graphic) film typically include providing a first PLA-based film as described herein and providing a graphic on the film. In some embodiments, the PLA-based film is typically annealed prior to providing the graphic film (e.g., prior to printing). The film can be annealed during production or immediately prior to providing a graphic on the film, such as by printing. Annealing conditions can vary from about 12 hours at 120°F to about 20 minutes at about 200°F. In some embodiments, the storage and / or shipping environment of the film provides sufficient annealing. In other embodiments, the PLA-based film is unannealed during production. Additionally, the PLA-based film may be unannealed prior to providing the graphic film (e.g., prior to printing). In one embodiment, the first film layer, during production and / or printing, has a net endotherm of melting ΔH of less than 10 J / g in the first heating scan. nm1 It has.

[0160] A variety of methods can be used to provide graphics on the film, with typical techniques including, for example, inkjet printing, thermomelt transfer, flexography, dye sublimation, screen printing, electrostatic printing, offset printing, gravure printing, or other printing processes.

[0161] The graphic may be one color or multiple colors. In the case of security marking, the graphic may be indistinct when viewed at wavelengths in the visible light range. The graphic may be a continuous or discontinuous layer.

[0162] Referring to FIG. 1, graphic article 100 includes graphic 110 adjacent a major surface of first PLA-based film layer 101. The first film layer (101, 201, 301, 401, 501, 601, 701, 801) can be a monolithic film or film layer comprising a semicrystalline polylactic acid polymer, a second (e.g., polyvinyl acetate polymer) having a Tg of at least 25°C, and a plasticizer, as described above. In another embodiment, referring to FIG. 2, graphic 210 of graphic article 200 can be disposed on a (e.g., transparent) ink-receiving (e.g., coating) layer 220. In this embodiment, ink-receiving (e.g., coating) layer 220 is disposed on, and typically in contact with, first film layer 201. Although not shown, each of the embodiments of FIGS. 3-8 may optionally further include an ink-receiving layer between the graphic and the first film layer. The graphics ( 110 , 210 , 310 , 410 , 510 , 610 , 710 ) are typically permanently adhered to the first film layer or ink-receiving layer 220 .

[0163] The ink-receiving layer can be characterized as a primer for the ink. In some embodiments, the ink-receiving layer can be characterized as a clear or colorless ink. Various other ink-receiving (e.g., coating) layers are known, including those described in U.S. Patent Nos. 7,025,453, 6,881,458, and 6,846,075, the entire contents of which are incorporated herein by reference. Transparent inks can also be used as ink-receiving layers.

[0164] In some embodiments, the first PLA-based film layer (101, 201, 501, 601, 701, 801) can be characterized as a backing. The opposing major surface of the first film layer (e.g., 106 in Figure 1) is typically adhered to a target surface by a (e.g., pressure-sensitive) adhesive. The pressure-sensitive adhesive is typically covered by a removable release liner, as described above.

[0165] In another embodiment, the first PLA-based film layer (301, 401, 601) can be characterized as a cover film, with the (e.g., reverse imaged) graphics (310, 410, 610) visible through the cover film.

[0166] The graphic article may further include an additional second layer, as described above.

[0167] In one embodiment, as shown in FIG. 3 , graphic article 300 includes a first PLA-based film layer 301 (e.g., a cover film), a graphic 310 adjacent a major surface of first film layer 301, and a backing 350 disposed on an opposing surface of graphic 310.

[0168] In another embodiment, as shown in FIG. 4 , a graphic article 400 includes a first PLA-based film layer 401 (e.g., a cover film), a graphic 410 adjacent a major surface of the first film layer 401, and a (e.g., pressure-sensitive) adhesive 430 that adheres the (e.g., reverse image) film (401) (together with 410) to a backing 450.

[0169] In another embodiment, as shown in FIG. 5, a graphic article 500 includes a first PLA-based film layer 501, a graphic 510 adjacent a major surface of the first film layer 501, and a topcoat or cover film 550 disposed on an opposing surface of the graphic 510.

[0170] In another embodiment, as shown in FIG. 6 , a graphic article 600 includes a first PLA-based (e.g., opaque) film layer 601b, a graphic 610 adjacent a major surface of the first film layer 601b, and a (e.g., pressure-sensitive) adhesive 630 adhering the (e.g., substantially transparent) first PLA-based film layer (e.g., cover film) 601a to the opposing surface of the graphic 610.

[0171] In another embodiment, as shown in FIG. 7, a graphic article 700 includes a (e.g., substantially transparent) first PLA-based film layer 701a (e.g., a cover film), a (e.g., reverse image) graphic 710 adjacent to a major surface of the first film layer 701a, and a (e.g., pressure-sensitive) adhesive 730 that adheres the (e.g., reverse image) film (701) (together with 710) to the first film layer (e.g., a backing) 701b.

[0172] In the embodiment of Figures 6-7, the first film layer (e.g., backing) 601b and 701b and the (e.g., substantially transparent) cover film 601a and 701a comprise a semi-crystalline polylactic acid polymer, a second (e.g., polyvinyl acetate) polymer having a Tg of at least 25°C, and a plasticizer, as described above.

[0173] The backing (e.g., 350, 450) can be any of the flexible and non-flexible substrates described above. In some embodiments, the backing is a conformable film layer, as described above. Additionally, the topcoat or cover film 550 can also be any of the substantially transparent (e.g., low surface energy) hardcoats, conformable films, etc., as described above. In one embodiment, the topcoat comprises a clear ink that is applied over the (e.g., pigmented) graphics.

[0174] In each of the embodiments of Figures 1-7, the graphic is disposed on a first film layer comprising a semi-crystalline polylactic acid polymer, a second (e.g., polyvinyl acetate) polymer having a Tg of at least 25°C, and a plasticizer, as described above, or the graphic is disposed on an ink-receiving layer, which is disposed on a PLA-based film.

[0175] However, in other embodiments, the graphic is disposed on a second film, which second film is free of a semi-crystalline polylactic acid polymer, a second (e.g., polyvinyl acetate) polymer having a Tg of at least 25°C, and a plasticizer, as described herein. Alternatively, the graphic is disposed on an ink-receiving layer disposed on a second film. The second film is then adhered to a PLA-based film, as described herein. For example, in one embodiment, as shown in FIG. 8, a graphic article 800 includes a (e.g., substantially transparent) cover film 850, a (e.g., reverse image) graphic 810 adjacent a major surface of the cover film 850, and a (e.g., pressure-sensitive) adhesive 830 that adheres the (e.g., reverse image) cover film (850) (together with 810) to a first film layer (e.g., backing) 801. In this embodiment, the first film layer 801 includes a PLA-based film, as described herein, and the cover film 850 includes a different polymeric material, such as a different conformable film.

[0176] In another embodiment, not shown, the graphic film is the same as that of Figure 4, except that the order of the graphic 410 and adhesive 430 is reversed. The graphic film includes a second (e.g., backing) film 450 including a graphic that is adhesively adhered to a first film layer (e.g., cover film) that includes a PLA-based polymer, as described herein.

[0177] Various other configurations in which the graphic film comprises a PLA-based film may be made in combination with a graphic as described herein.

[0178] The graphics typically include a dried and / or cured ink layer. The dried ink layer may be derived from a wide variety of ink compositions, including, for example, organic solvent-based inks or water-based inks. The dried or cured ink layer may also be derived from a wide variety of radiation (e.g., ultraviolet) curable inks.

[0179] Pigmented inks typically contain a colorant, such as a pigment and / or dye, dispersed in a liquid carrier. The liquid carrier may include water, an organic monomer, a polymerizable reactive diluent in the case of radiation-curable inks, or a combination thereof. For example, latex inks typically contain water and a (e.g., non-polymerizable) organic cosolvent.

[0180] A wide variety of organic and inorganic pigments are known in the art for use in inks. Suitable pigments include, but are not limited to, azo pigments (such as condensed and chelated azo pigments), polycyclic pigments (such as phthalocyanines, anthraquinones, quinacridones, thioindigoids, isoindolinones, and quinophthalones), nitro pigments, daylight fluorescent pigments, carbonates, chromates, titanium oxide, zinc oxide, iron oxide, and carbon black. In one embodiment, the pigment is other than a white pigment (such as titanium dioxide). Pigments used in the ink composition can include carbon black and pigments capable of producing cyan, magenta, and yellow inks. Suitable commercially available pigments include, for example, Pigment Red 81, Pigment Red 122, Pigment Yellow 13, Pigment Yellow 14, Pigment Yellow 17, Pigment Yellow 74, Pigment Yellow 83, Pigment Yellow 128, Pigment Yellow 138, Pigment Orange 5, Pigment Orange 30, Pigment Orange 34, Pigment Blue 15:4, and Pigment Blue 15:3.

[0181] In some embodiments, such as inkjet printing inks, the pigment dispersion particles are small enough to allow the ink to flow and pass through inkjet equipment, particularly inkjet printing nozzles, typically ranging from about 10 to about 50 microns in diameter, more typically about 30 microns or less. In some embodiments, the pigment dispersion particles range from 50 nm to about 200 nm in diameter, more typically 120 nm or less. Larger pigment particles may be used for screen printing inks and, as noted above, for materials used in other printing techniques. However, smaller size pigment particles also typically provide the highest color strength.

[0182] The organic solvent of the ink may be a single solvent or a blend of solvents. Suitable solvents include alcohols (such as isopropyl alcohol (IPA) or ethanol), ketones (such as methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), diisobutyl ketone (DIBK), cyclohexanone, or acetone), ethers (such as dialkylene glycol dialkyl ethers, such as tetraethylene glycol dimethyl ether and diethylene glycol diethyl ether), aromatic hydrocarbons (such as toluene), isophorone, butyrolactone, N-methylpyrrolidone, tetrahydrofuran, esters (lactate, acetate, ethyl 3-ethoxypropionate, and propylene glycol monomethyl ether acetate, such as those available from 3M under the tradename "3M Scotchcal Thinner CGS10" ("CGS10")), 2-butoxyethyl acetate (available from 3M under the tradename "3M Scotchcal Thinner CGS10" ("CGS10")), and methyl ketones (such as methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), diisobutyl ketone (DIBK), cyclohexanone, or acetone). and the like, commercially available as "CGS50" ("CGS50"), diethylene glycol ethyl ether acetate (DE acetate), ethylene glycol butyl ether acetate (EB acetate), dipropylene glycol monomethyl ether acetate (DPMA), iso-alkyl esters (including isohexyl acetate, isoheptyl acetate, isooctyl acetate, isononyl acetate, isodecyl acetate, isododecyl acetate, isotridecyl acetate, or other iso-alkyl esters), and combinations thereof.

[0183] Ink compositions, especially those durable for outdoor use, typically further comprise a polymeric binder. The binder is typically compatible with the pigment particles so that, after evaporation of the volatile components of the ink, the binder forms a film of the pigment deposited on the first film layer. Suitable binders include vinyl-containing polymers, acrylic-containing polymers, urethane-containing polymers, mixtures thereof, and binders containing multiple such moieties (e.g., both urethane and (meth)acrylate moieties). In the case of radiation-curable inks, the binder may be formed from polymerization of a reactive diluent during curing of the ink.

[0184] In some embodiments, the ink layer is an inkjet printing layer. Inkjet printing is a method of printing by spraying ink droplets through computer-controlled nozzles. The viscosity of inkjet printing inks typically ranges from about 3 to about 30 centipoise at printhead operating temperatures. The viscosity of such inks is preferably less than about 25 or about 20 centipoise at the desired inkjet temperature (typically ambient to about 65°C or less). Inkjet compositions are formulated to characteristically have low surface tension properties. The surface tension of preferred formulations is in the range of about 20 mN / m to about 50 mN / m, more preferably about 22 mN / m to about 40 mN / m, at printhead operating temperatures. Furthermore, inkjet inks typically have Newtonian or substantially Newtonian viscosity properties.

[0185] Inkjet printing principally relies on the use of four colors: cyan, magenta, yellow, and black (CMYK). However, to improve image resolution, some of the printers identified above may also include two additional colors, called "light cyan" and "light magenta," which are lower density related cyan and magenta inks.

[0186] In one embodiment, the inkjet ink is a solvent-based ink comprising 1 to 5 parts by weight of a colorant (e.g., a pigment), 1 to 10 parts by weight of an oligomeric or polymeric binder, and up to 115 parts of various organic solvents (as described above, including, for example, diethylene glycol diethyl ether, γ-butyrolactone, tetraethylene glycol dimethyl ether, and dialkylene glycol dialkyl ethers). In one embodiment, the inkjet ink comprises diethylene glycol diethyl ether (e.g., 40 to 50% by weight), γ-butyrolactone (e.g., less than 20% by weight), tetraethylene glycol dimethyl ether (e.g., 10 to 20% by weight), and dialkylene glycol dialkyl ether (e.g., 15 to 25% by weight).

[0187] In another embodiment, the inkjet ink may be a water-based ink, or in other words, an aqueous inkjet ink. The liquid medium typically comprises at least 50%, 60%, 70%, or 80% by weight of distilled and / or deionized water, and may comprise water in combination with one or more water-miscible organic solvents.

[0188] In one embodiment, the liquid medium of the aqueous inkjet ink comprises water (eg, 60-90%), an organic solvent such as 2-pyrrolidone (15% or less), and a colorant such as carbon black (5% or less).

[0189] In other embodiments, the aqueous inkjet ink further includes a polymer binder, such as a latex binder, typically formed by emulsion polymerization. In one embodiment, the latex binder is formed by emulsion polymerization of a first monomer having a higher glass transition temperature (Tg) and a second monomer having a lower glass transition temperature (Tg). The glass transition temperature of a monomer more specifically refers to the glass transition temperature of a homopolymer formed from the specific monomer. In one embodiment, the latex binder is formed from a first monomer having a glass transition temperature (Tg) greater than about 70°C. The first monomer may include styrene, substituted styrene, methyl methacrylate, or a mixture thereof. Examples of substituted styrenes include alkyl-substituted styrenes and halogen-substituted styrenes. In a preferred embodiment, the average glass transition temperature (Tg) of the first monomer or the mixture thereof is about 100°C or greater. The glass transition temperature (Tg) of the second monomer of the latex binder is typically less than about 0°C. The second monomer may include an alkyl acrylate such as ethyl acrylate, propyl acrylate, butyl acrylate, octyl acrylate, ethylhexyl acrylate, etc. In some embodiments, the glass transition temperature, Tg, of the second monomer is less than about −25° C. or −50° C. The ratio of the first and second monomers can be varied to provide a latex binder with a glass transition temperature, Tg, ranging from about 0° C. to 70° C.

[0190] The reaction medium for preparing the latex binder may contain a charge stabilizing agent and / or an emulsifier to achieve the desired particle size. The average particle size of the latex binder is typically 20 nm to 500 nm, and in some embodiments, 100 nm to 300 nm. The weight average molecular weight of the latex binder may range from 10,000 to 5,000,000 g / mol. Various charge stabilizers are known, such as methacrylic acid, acrylic acid, and / or their (e.g., sodium) salts. Various emulsion polymerization emulsifiers are also known, such as fatty acid (e.g., lauric acid) ether sulfates.

[0191] Latex ink compositions also typically contain dispersants and / or humectants (also known as cosolvents). Non-polymeric dispersants include naphthalene sulfonic acid, sodium lignosulfate, glycerol stearate, and phosphate-containing surfactants. Many polymeric dispersants are known. Such polymers typically contain both a hydrophilic portion for water affinity and a hydrophobic portion for interaction with the pigment.

[0192] In one embodiment, the aqueous inkjet ink composition may include a pigment, a co-solvent, a dispersant, and a latex binder. The aqueous composition may include from 1% to 10%, 15%, or 20% pigment, at least 5%, 10%, 30%, 40%, or 50% co-solvent, from 0.01% to 5%, or 10%, dispersant, and at least 1%, 2%, 5%, 10%, 15%, or 20% latex binder.

[0193] Various water-based latex (eg, ink-jet) inks are known, such as those described in US Pat. Nos. 9,175,181 and 6,498,202.

[0194] "Radiation-curable" inks contain components with functionality pendant directly or indirectly from the backbone that react (e.g., crosslink) upon exposure to a suitable curing energy source. Suitable radiation crosslinkable groups include epoxy groups, (meth)acrylate groups, olefinic carbon-carbon double bonds, allyloxy groups, α-methylstyrene groups, (meth)acrylamide groups, cyanate ester groups, vinyl ether groups, combinations thereof, and the like. Typically, free-radically polymerizable groups are preferred. Of course, (meth)acrylic moieties are especially preferred. As used herein, the term "(meth)acrylic" encompasses acrylic and / or methacrylic.

[0195] The energy source used to crosslink the radiation-curable functional groups can be actinic radiation (e.g., radiation having wavelengths in the ultraviolet (UV) or visible spectral regions), accelerated particles (e.g., electron beam (EB) radiation), heat (e.g., thermal or infrared radiation), etc., with UV and EB being preferred. Suitable sources of actinic radiation include mercury lamps, xenon lamps, carbon arc lamps, tungsten filament lamps, lasers, electron beam energy, light emitting diodes, sunlight, etc.

[0196] The radiation curable material may be mono-, di-, tri-, tetra-, or otherwise multifunctional in terms of the radiation curable moiety. The radiation curable material may be linear, branched, and / or cyclic, with branched materials tending to have lower viscosities than linear materials of comparable molecular weight.

[0197] When the radiation-curable material is a monomer, it may be referred to as a reactive diluent. A variety of reactive diluents are suitable, including acrylate monomers (such as hexanediol diacrylate, tetrahydrofurfuryl acrylate, isobornyl acrylate, ethoxyethoxyethyl acrylate, propoxylated neopentyl glycol diacrylate, and trimethylolpropane triacrylate) and vinyl monomers (such as vinyl caprolactam).

[0198] In some embodiments, the radiation curable ink comprises at least 25, 30, 35, 40, up to 90% by weight, or more, of such reactive diluent monomers.

[0199] The radiation curable ink may optionally further comprise an organic solvent in the range of at least 5, 10, 15, or 30% by weight, up to 50% by weight.

[0200] In one embodiment, the radiation curable ink includes an organic solvent (e.g., 30-45% by weight) such as (tetrahydrofurfuryl) alcohol and a mixture of acrylate and vinyl monomers. For example, the monomers may include vinyl caprolactam (e.g., 10-20% by weight), isobornyl acrylate (e.g., 10-20% by weight), propoxylated neopentyl glycol diacrylate (e.g., 1-5% by weight), and cyclic trimethylolpropane formal acrylate (e.g., 1-5% by weight).

[0201] In other embodiments, the radiation curable ink composition further comprises one or more polymeric binders. The polymeric binders may be oligomers or macromonomers having a number average molecular weight (Mn) of at least 3,000, 4,000, 5,000, or 6,000 g / mol, up to and including 10,000 or 15,000 g / mol. Alternatively, the molecular weight of the polymeric binder may be higher.

[0202] In some embodiments, the polymeric binder comprises methyl methacrylate, isobutyl methacrylate, or isobutyl methacrylate / isooctyl acrylate repeat units. The polymeric binder may have methyl / methacrylate repeat units and methacrylic acid end groups. The polymeric binder may be present in an amount of at least 10, 15, 20, or 25% by weight of the ink, up to 35, 40, 45, 50, 55, or 60% by weight.

[0203] Water-based, solvent-based, and radiation-curable inks may contain a variety of optional additives, including one or more of flow control agents, slip modifiers, thixotropic agents, surfactants (e.g., fluorochemicals), foaming agents, defoamers (e.g., silica and silicone oils), flow or other rheology control agents, waxes, oils, antioxidants, photoinitiators and photoinitiator stabilizers in the case of radiation-curable inks, dispersants, gloss agents, fungicides, bactericides, organic and / or inorganic filler particles, leveling agents, opacifiers, antistatic agents, dispersants, etc. Various commercially available stabilizing chemicals, such as hydrolysis stabilizers, heat stabilizers, UV stabilizers, and free-radical scavengers, may also be added to improve the durability of designs, images, etc., especially in outdoor environments exposed to sunlight.

[0204] The inclusion of inorganic fillers, such as crystalline and amorphous silica, aluminum silicate, and calcium carbonate, increases surface roughness, reduces gloss, and improves dot gain. The concentration of inorganic fillers is typically about 0.1% to about 10% by weight, preferably about 0.5% to about 5% by weight. The particle size is preferably less than 1 micron, more preferably less than 0.5 microns, and most preferably less than about 0.2 microns.

[0205] Representative inkjet printing inks include, for example, HP Latex 360 Printer (HP 83 Inks), Roland XR-640 (Roland ESL4 Eco Inks), and EFI VUTEk GS3250LX Pro (EFI VUTEk GSLXr 3M® SuperFlex UV Ink).

[0206] In another embodiment, the graphic comprises a screen printing ink. Screen printing is a printing method in which ink is forced through an assembly of mesh fabric and a stencil using a squeegee. The screen printing ink also comprises a polymer binder dispersed (e.g., 40-60% by weight) in a liquid carrier, a colorant (in the case of a colored ink), and the optional additives and inorganic fillers described above. However, higher molecular weight polymer binders may also be used in screen printing inks. Furthermore, screen printing inks typically contain greater than 40% solids and have viscosities at least two orders of magnitude higher than those of inkjet printing inks.

[0207] In some embodiments, the screen printing ink may be an organic solvent-based screen printing ink comprising an acrylic and / or vinyl polymer binder. Suitable acrylic polymer binders include methyl methacrylate polymers and copolymers. In some embodiments, the screen printing ink may comprise 5 to 10 wt. % of the acrylic polymer binder. Suitable vinyl polymer binders include copolymers of vinyl acetate, vinyl alcohol, and vinyl chloride. In some embodiments, the screen printing ink may comprise 10 to 20 wt. % of the vinyl polymer binder.

[0208] The screen printing ink may further comprise up to 15 wt. % of a plasticizer, including polymeric plasticizers and phthalates (e.g., diundecyl phthalate), a colorant (e.g., a pigment), and 1-5 wt. % of an inorganic filler, as described above. The organic solvent-based screen printing ink comprises 40-60 wt. % of an organic solvent, as described above. In one embodiment, the screen printing ink comprises cyclohexane (e.g., 35-45 wt. %), ethyl 3-ethoxypropionate (e.g., 10-20 wt. %), and 2-butoxyethyl acetate (e.g., 5-10 wt. %).

[0209] In another embodiment, the screen printing ink is a radiation curable ink comprising at least one polymer dispersed in a reactive diluent as the liquid carrier, a colorant (in the case of a pigmented ink), and the optional additives and inorganic fillers described above. In one embodiment, the radiation curable screen printing ink comprises 10-20 wt. % of a methyl methacrylate polymer, a colorant (e.g., a pigment), up to 5 wt. % of an inorganic filler as described above, and up to 90 wt. % of a mixture of reactive diluents. In one embodiment, the radiation curable screen printing ink comprises an aromatic (meth)acrylate monomer such as phenoxyethyl acrylate (e.g., 30 to 40% by weight), an aliphatic urethane acrylate (e.g., 5 to 15% by weight), vinyl caprolactam (e.g., 10 to 20% by weight), 1-propanone (e.g., 1 to 5% by weight), 2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-2-(phenylmethyl), 1-butanone (e.g., 1 to 5% by weight), 2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-2-(phenylmethyl), diethylene glycol ethyl ether acrylate (e.g., 1 to 5% by weight), and propoxylated glycerol triacrylate (e.g., 1 to 5% by weight).

[0210] Suitable examples of screen printing inks include 3M® Screen Printing UV Ink 9802 Opaque Black, 3M® Scotchlite® Transparent Screen Printing Ink 2905 Black, and those described in U.S. Pat. No. 6,232,359.

[0211] In advantageous embodiments, the color density is at least 80, 85, 90, 95, or 100% of the color density obtainable with cast vinyl film (eg, SCOTCHCAL IJ170-10 and IJ180mc-10, available from 3M).

[0212] Objects and advantages of this invention are further illustrated by the following examples, in which the particular materials and amounts recited, as well as other conditions and details, should be used in a manner that does not unduly limit this invention. [Example]

[0213] Unless otherwise noted, all parts, percentages, ratios, etc. in the examples and elsewhere in this specification are by weight. Unless otherwise indicated, all other reagents were obtained or are available from fine chemical suppliers such as Sigma-Aldrich Company (St. Louis, Missouri), or can be synthesized by known methods.

[0214] material INGEO 4032D-semicrystalline polylactic acid (PLA) (2 wt% D-lactide; weight average molecular weight ≈ 200,000 g / mol) was purchased from Natureworks, LLC (Minnetonka, MN).

[0215] INGEO 4060 D-amorphous polylactic acid (PLA) (10 wt% D-lactide; weight average molecular weight ≈ 180,000 g / mol) was purchased from Natureworks, LLC (Minnetonka, MN).

[0216] VINNAPAS UW 4 FS-polyvinyl acetate (PVAc) (Tg=42°C; weight average molecular weight ≈280,000 g / mol) was obtained from Wacker (Germany).

[0217] VINNAPAS UW 25 FS-polyvinyl acetate (PVAc) (Tg=42°C; weight average molecular weight ≈480,000 g / mol) was obtained from Wacker (Germany).

[0218] VINAVIL K70 - Polyvinyl acetate (Tg = 42°C; weight average molecular weight ≈ 640,000 g / mol) was obtained from Vinavil (Italy).

[0219] CITROFLEX A4 - Plasticizer, acetyl tributyl citrate, was obtained from Vertellus Performance Materials (Bayonne, NJ).

[0220] TEGMER 804 - tetraethylene glycol di-ethylhexonate ester plasticizer was obtained from Hallstar (Chicago, IL).

[0221] TEGMER 809-PEG 400 di-ethylhexonate ester plasticizer was obtained from Hallstar (Chicago, IL).

[0222] ADMEX 6995 - polymeric adipate plasticizer (weight average molecular weight ≈3200 g / mol) was obtained from Eastman Chemical Company (Kingsport, TN).

[0223] ECOPROMOTE-nucleating agent zinc phenylphosphonate was obtained from Nissan Chemical Industries.

[0224] STABAXOL ILF - Hydrolysis stabilizer was obtained from LANXESS Corporation (Pittsburgh, PA).

[0225] CARBODILITE HMV-15CA - hydrolysis stabilizer was obtained from Nisshinbo Chemical.

[0226] SUKANO DC S511 - Antiblocking additive masterbatch was obtained from Sukano Polymers Corporation (Duncan, SC).

[0227] CLARIANT PLA4060 TiO2MB - 50 wt% titanium dioxide in 50 wt% amorphous Ingeo PLA 4060D masterbatch was obtained from Clariant Corporation (Minneapolis, MN).

[0228] CLARIANT PLA4032 TiO2MB - 50 wt% semi-crystalline Ingeo PLA 4032D 50 wt% titanium dioxide in masterbatch was obtained from Clariant Corporation (Minneapolis, MN).

[0229] TI-PURE R-350 - Titanium dioxide pigment was obtained from The Chemours Company FC (Wilmington, Del.).

[0230] TI-PURE R-960 - Titanium dioxide pigment was obtained from The Chemours Company FC (Wilmington, Del.).

[0231] Cover film - a non-PVC overlaminate with the trade designation ENVISION 8584G (film thickness is approximately 0.002 inches, or 50.8 micrometers) was obtained from 3M Company (Maplewood, MN).

[0232] Commercially available from SCOTCHCAL IJ 170-10-3M (Maplewood, MN).

[0233] It is commercially available from CONTROLTAC 40C-10-3M (Maplewood, MN).

[0234] Commercially available from 3M IJ180MC-10-3M (Maplewood, MN).

[0235] Sample preparation Melting and kneading 15cm 3Samples were prepared by mixing PLA, PVAc, plasticizer, and nucleating agent in a hot melt extruder (DSM XPLORE) equipped with a twin-screw mini-kneader at 100 revolutions per minute (RPM) at 200°C for 10 minutes, then opening the mixing chamber valve and collecting the sample. The compounded samples were subjected to aging tests at 80°C and differential scanning calorimetry ("DSC") characterization, and melt pressed into films for tensile testing.

[0236] Melt pressing to make film The kneaded sample was placed between two polytetrafluoroethylene sheets with a 10 mil (approximately 250 micrometer) spacer between them. The polytetrafluoroethylene sheets were sandwiched between metal sheets. The metal sheets with the sample between them were placed between the platens of a hydraulic press (available from Carver), and the platens were heated to 340°F (171°C). Each sample was preheated for 8 minutes without pressure, then pressed under 300 pounds per square inch (approximately 2.1 Newtons per mm). 2 ) for 5 minutes. The metal plate was then removed from the hydraulic press and allowed to cool.

[0237] Test Method Aging test The kneaded samples (approximately 0.2 grams) were placed in scintillation vials, closed to prevent evaporation of the plasticizer during the aging test, and aged in an oven at 80° C. for 24 hours. The sample surfaces were then inspected to determine whether there was any plasticizer migration after aging at 80° C. Samples with an oily surface were considered to have failed, and samples with a non-oily surface were considered to have passed.

[0238] DSC - Differential Scanning Calorimetry The glass transition temperature, crystallization temperature, and crystallinity of each sample were measured according to ASTM D3418-12 using a TA Instruments Differential Scanning Calorimeter, unless otherwise specified. Each sample (4–8 milligrams (mg)) was heated from −60°C to 200°C at 10°C / min in the first heating scan, held for 2 minutes to erase the thermal history, then cooled to −60°C at 10°C / min in the first cooling scan (unless otherwise specified), and heated to 200°C at 10°C / min in the second heating scan. The first heating scan was used to determine the Tm of the film. The second heating scan was used to determine the Tg of the film. Various parameters were derived from the DSC as defined below.

[0239] T g - ASTM D3418-12 T mg This refers to the intermediate temperature of the second heating scan.

[0240] T c - ASTM D3418-12 T pc This refers to the crystallization peak temperature of the first cooling scan, which is written as

[0241] T m1 and T m2 - ASTM D3418-12, respectively T pm The melting peak temperatures of the first and second heating scans are indicated as

[0242] The ability of a composition to crystallize is determined by the net melting endotherm ΔH associated with the crystalline material formed during the first cooling scan, calculated using the following equation: nm2 was determined by calculating ΔH nm2 =ΔH m2 -ΔH cc2 (In the formula, ΔH m2 is the mass-normalized enthalpy of the melting endotherm of the second heating scan, and ΔH cc2is the mass-normalized enthalpy of the crystallization exotherm of the second heating scan (as described in Section 11 of ASTM D3418-12). For compositions containing a nucleating agent, ΔH cc2 was not detected, so ΔH nm2 =ΔH m2 It was.

[0243] Net melting endotherm ΔH nm1 is related to the degree of crystallinity in films (prepared, for example, by melt pressing). nm1 is expressed as follows: ΔH nm1 =ΔH m1 -ΔH cc1 [In the formula, ΔH m1 is the mass-normalized enthalpy of the melting endotherm of the first heating scan, and ΔH cc1 is the mass-normalized enthalpy of crystallization exotherm of the first heating scan (as described in Section 11 of ASTM D3418-12). For films containing a nucleating agent, ΔH cc1 was not detected, so ΔH nm1= ΔH m1 It was.

[0244] The absolute value of the enthalpy associated with the heat release and absorption (i.e., ΔH m1 , ΔH m2 , ΔH cc1 , and ΔH cc2 ) was used in the calculation.

[0245] Tensile test Film samples were cut into 0.5- or 1-inch (1.27- or 2.54-centimeter (cm))-wide strips. Tensile tests were performed along the machine direction (MD) and transverse direction (TD) of the film extrusion using an Instron 3365 tensile tester. The initial grip distance was 1 inch (approximately 2.5 cm), and the pull rate was 6 inches / minute (approximately 15.2 cm / minute) (i.e., 600% strain / minute) (unless otherwise specified). Test results were reported as the average of three to five sample replicates. Tensile strength (nominal), tensile elongation (percent elongation at break), and tensile modulus were determined as described in ASTM D882-10, sections 11.3 and 11.5.

[0246] Gel Permeation Chromatography (GPC) The samples were analyzed by conventional GPC against polystyrene molecular weight standards. The GPC instrument was an Agilent 1260. The GPC column set was an Agilent PL Gel Mixed B and D (2 x 300 x 7.8 mm ID), and the eluent was THF solvent. The peak molecular weight (M p ), number average molecular weight (M n ) and weight average molecular weight (M w ) reported.

[0247] Accelerated Weathering Test specimens were exposed to accelerated weathering conditions in an Atlas Ci5000 Xenon Weather-Ometer manufactured by Atlas Material Testing Technology, 4114 North Ravenswood Avenue, Chicago, Ill., 60613. Testing was conducted in accordance with ASTM G155-13, "Standard Practice for Operating Xenon Arc Light Apparatus for Exposure of Non-Metallic Materials," with customized settings outlined in Cycle 1 of Table X3.1 in Appendix X1 of ASTM G155-13. The customized settings were as follows: Irradiance: 0.68W / m at 340nm 2 End Black panel temperature: 70℃ (light cycle), 70℃ (light and water cycle) Chamber temperature: 47°C (light cycle), 47°C (light and water cycle) Relative humidity: 70% (light cycle), 95% (light and water cycle) The test sample was exposed to 295-385 nm (MJ / m 2 ) total exposure dose.

[0248] Dynamic Mechanical Analysis (DMA) Dynamic mechanical analysis (DMA) was performed to evaluate the physical properties of the films as a function of temperature using a film tensile fixture available from TA Instruments as a "DMA Q800." Samples were heated from a temperature of -40°C to 140°C at a rate of 2°C / min, a frequency of 1 rad / sec, and a tensile strain of 0.1%.

[0249] Printing performance analysis Printability was evaluated using the absolute print density test method according to ASTM D7305-08a, "Standard Test Method for Reflection Density of Printed Matter," and a GRETAG SPM 50 LT spectrodensitometer with a 5 mm aperture on the measuring head. The spectral response was calibrated using a calibration plaque and found to be accurate to within 2%. Laminates of 25 micrometer (0.001 inch) thick acrylic pressure-sensitive adhesive layers on whitened paper release liners were nip-roll laminated at room temperature into the following films such that the adhesive and film surfaces bonded together to form film articles: Printability was evaluated using the following various types of printers, each measuring at least 15 cm. 2 The exposed surface of the film article was printed with primary color bars covering the .alpha. VUTEK ULTRAVU II Model 150 SC printer (obtained from VUTEK, a division of EFI Corporation, Meredith, NH) using 3M® Piezo Inkjet Ink Series 1500v2; A SOLJET PRO4 XR-640 printer using Eco-Sol Max 2 ink (obtained from Roland DGA Corporation, Irvine, CA), · An HP LATEX 360 printer using HP Latex inks (obtained from The Hewlett-Packard Company, Palo Alto, CA).

[0250] After printing, the samples were allowed to air dry for a minimum of 24 hours before measuring the print density of the color bar.

[0251] To compare the ink color density of an example film to that of Control 1, the print density of the example film is divided by the print density of Control 1 and the result is expressed as a percentage of baseline performance. Achievement of 100% indicates baseline saturation. Values greater than 100% represent higher saturation, and values less than 100% represent lower saturation. Total color density is the sum of measurements for cyan, magenta, yellow, and black.

[0252] Color change The initial color of printed PLA films (including the laminated cover film described below) and the color change after accelerated weathering were measured with an X-Rite Ci64 spectrophotometer. Color was measured using a Hunter L * , a * , b * The color was measured in units of 100 kJ / s and the color change (ΔE, Delta E) was calculated according to ASTM D2244 "Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally Measured Color Coordinates."

number

[0253] The weight percent of each of the components used in the compositions of the examples and controls (designated "C") is shown in Table 1. For example, Example 8 contained 70 wt. % PLA4032, 15 wt. % PVAc, and 15 wt. % CIROFLEX A4, based on the total weight of the polylactic acid polymer, polyvinyl acetate polymer, and plasticizer. Example 8 also contained 0.2 wt. % Ecopromote, based on the total weight of the composition. The Tg and aging results of the compositions are also reported in Table 1, as follows: [Table 1]

[0254] As shown in Table 1, Comparative Examples C1, C4, and C5 passed the aging test, while Comparative Examples C2, C3, C6, and C7 failed the aging test. The Tg of the sample can decrease to 25° C. (as shown by Comparative Example C5) but still pass the aging test above 25° C. (as shown by Comparative Examples C6 and C7). If the composition included PLA, a plasticizer, and PVAc, the Tg could decrease below 25° C. and still pass the aging test.

[0255] The wt% of each of the components used in the compositions of the Examples and Controls (designated "C"), along with the DSC results, are shown in Table 2 below: [Table 2]

[0256] A representative DSC profile of the composition of Example 12 is shown in Figure 9. This DSC profile shows a sharp crystallization peak exotherm during cooling. As shown in Figure 10, the composition of Example 16 does not show any crystallization during cooling.

[0257] Film samples of Examples 12 and 16 were tested according to the dynamic mechanical analysis described above, with the results for Example 12 shown in Figure 11 and the results for Example 16 shown in Figure 12.

[0258] The DSC and tensile test results (1 in / min (ie, 100% strain / min)) of these films are shown in Table 3 below. [Table 3]

[0259] The aforementioned PLA-based films can be utilized in a variety of graphic articles as backings, intermediate layers, or cover films. Graphics can be provided on the PLA-based films, particularly by printing with radiation-curable inks.

[0260] Example 22 Pre-mixed and flowable PLA pellets were prepared using a twin-screw extruder (Zone 1: 250°F or 121°C; Zones 2 and 3: 390°F or 199°C; Zones 4 and 5: 350°F or 177°C) and an underwater pelletizer, and had the following composition: [Table 4]

[0261] The pre-blended PLA pellets were fed into a single-screw extruder (Gloucester Engineering extruder, Gloucester, MA) with a 2-inch (approximately 5.1 cm) diameter screw and a 78-inch (198 cm) length. The extruder was operated at 14 rpm with a cooled feed throat and approximate zone and die temperatures as follows: Z1: 166°C (330°F), Z2: 168°C (335°F), Z3: 171°C (340°F), Z4: 174°C (345°F), Die: 177°C (350°F). Films were extruded onto a 30-inch (76.2 centimeter (cm)) polyester carrier film through a 0.004-inch (0.102 millimeter (mm)) die gap, providing a film product having a thickness of approximately 0.002 inch (0.051 mm) and a width of approximately 30 inches (76.2 cm). The films were thermally annealed offline in an oven at 60°C (140°F) for approximately 3 hours to achieve crystallization. The polyester carrier was removed from the film product prior to testing. [Table 5]

[0262] Hydrolysis stabilizers (e.g., carbodiimides) and / or (TiO2) pigments can be added to any of the foregoing examples in the concentrations described herein.

[0263] Representative film examples were printed with various inks and evaluated for print density as described above. The test results are shown in the table below. [Table 6] [Table 7] [Table 8]

[0264] Example 23 A twin-screw extruder (Zone 1: 250°F or 121°C; Zones 2 and 3: 390°F or 199°C; Zones 4 and 5: 350°F or 177°C) and an underwater pelletizer were used to prepare pre-mixed and flowable PLA blend pellets having the following composition: [Table 9]

[0265] The pre-blended PLA pellets were dried in a desiccant dryer at 120°F (49°C) for approximately 15 hours and then fed into a single-screw extruder (Gloucester Engineering extruder, Gloucester, MA) with a 2.5 inch (6.4 cm) diameter screw and a 78 inch (198 cm) length. The extruder was operated with a cooled feed throat and approximate zone and die temperatures as follows: Zone 1: 330°F (166°C), Zone 2: 335°F (168°C), Zone 3: 340°F (171°C), Zone 4: 345°F (174°C), and Die: 350°F (177°C). The film was extruded through a die having a die gap of 0.004 mm (0.102 inch) onto a 30 inch (76.2 cm) wide polyester carrier film to provide a film product having a thickness of about 0.002 inch (0.051 mm) and a width of about 30 inches (76.2 cm). The film was thermally annealed offline in an oven at 55°C (131°F) for about 24 hours to achieve crystallization. [Table 10]

[0266] The annealed PLA film was then printed with the ink described above. The cover film (3M Envision 8548 G) was laminated onto the printed PLA film using a laminator at room temperature. The test specimen was then attached to an aluminum panel for accelerated weathering evaluation. The color of the printed film was measured before and after the accelerated weathering test. The results are summarized below. [Table 11] [Table 12]

[0267] Examples 24 to 28 [Table 13]

[0268] The extruded film samples of Examples 24-28 were prepared in the same manner as Example 23. [Table 14]

[0269] The unprinted film samples in Table 12A (simply films without a cover film) were evaluated under accelerated weathering conditions. Their molecular weights were analyzed by GPC. The results are summarized in Tables 13, 14, and 15. [Table 15] [Table 16] [Table 17] [Table 18]

[0270] Film samples were prepared by a laboratory melt pressing procedure (as described in the Sample Preparation section). Some of the film samples were annealed at 60° C. for 6 hours. Other samples were not annealed. [Table 19]

[0271] Print result [Table 20] [Table 21] [Table 22] [Table 23] [Table 24]

[0272] All references, patent documents or patent applications cited in the above patent application are incorporated herein by reference in their entirety for all purposes. In the event of any inconsistency or contradiction between any portion of an incorporated reference and this application, the information in the foregoing description shall prevail. The present invention includes the following aspects. (1) a first film layer, a semicrystalline polylactic acid polymer; an optional amorphous polylactic acid polymer; a second polymer having a Tg of at least 25°C; A plasticizer, a hydrolysis stabilizer; an inorganic pigment in an amount such that the ratio of polylactic acid polymer to inorganic pigment is less than 4.5:1; The article comprises a first film layer comprising: (2) The inorganic pigment is TiO 2 Item 1. (3) The article of item 1 or 2, wherein the amount of inorganic pigment is at least 15, 16, 17, 18, 19, or 20% by weight of the first film layer. (4) The article of any one of items 1 to 3, wherein the ratio of polylactic acid polymer to inorganic pigment is at least 1:1 and less than 4.4:1, 4.3:1, 4.2:1, 4.1:1, or 4:1. (5) The article according to any one of items 1 to 4, wherein the second polymer is a polyvinyl acetate polymer. (6) The article according to item 5, wherein the hydrolysis stabilizer is a carbodiimide compound. (7) The article according to any one of items 1 to 6, wherein the article is a graphic film further comprising a graphic proximate a major surface of the film layer. (8) The article of item 7, wherein the graphic comprises a dried and / or cured ink layer. (9) The article according to item 8, wherein the ink layer is a dried and / or cured radiation-cured ink, an organic solvent-based ink, or a water-based ink. (10) The article according to any one of items 7 to 9, further comprising a topcoat layer or cover film disposed on the graphic. (11) The article of item 10, wherein the cover film is adhered to the graphic by an adhesive layer. (12) The article according to item 10 or 11, wherein the cover film comprises a semicrystalline polylactic acid polymer. (13) The article according to any one of items 1 to 12, wherein the first film layer comprises an amorphous polylactic acid polymer. (14) The article according to any one of items 1 to 13, wherein the second polymer comprises a polyvinyl acetate polymer having a molecular weight in the range of 75,000 g / mol to 1,000,000 g / mol. (15) The article according to any one of items 1 to 14, wherein the plasticizer is present in an amount ranging from 5 to 35% by weight, based on the total amount of the polylactic acid polymer, the second polymer, and the plasticizer. (16) The article according to any one of items 1 to 15, further comprising a nucleating agent in an amount ranging from about 0.01% by weight to about 1% by weight. (17) The first film layer has the following properties: i) the first film layer does not exhibit plasticizer migration when aged at 80°C for 24 hours; ii) the first film layer has a Tg of less than 40°C, 35°C, 30°C, 25°C, or 20°C in a second heating scan at a rate of 10°C / min; iii) the first film layer has a tensile elongation of 50% to 600% at a strain rate of 600% / min; iv) the first film layer has a tensile modulus of 50 MPa to 1100 MPa at a strain rate of 600% / min; v) the first film layer has a tensile storage modulus, as determined by dynamic mechanical analysis, of at least 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 MPa in a temperature range of 25°C to 80°C when heated at a rate of 2°C / min; 17. The article of any of items 1 to 16, further characterized by any one or combination of: (18) The first film layer has a net melting endotherm ΔH of less than 10 J / g in a first heating scan at a rate of 10° C. / min. nm1 18. The article according to any one of items 1 to 17, comprising: (19) The article according to any one of items 1 to 18, wherein the first film layer is an annealed film. (20) The article according to any one of items 1 to 18, wherein the first film layer is an unannealed film. (21) The article according to any one of items 1 to 20, wherein the article further comprises a backing disposed on the surface opposite to the film layer. (22) The article according to any one of items 1 to 21, wherein the article further comprises a pressure-sensitive adhesive disposed on an opposing surface of the film layer or backing. (23) The first film layer has a net melting endotherm ΔH of less than 10 J / g in a second heating scan at a rate of 10° C. / min. nm2 23. The article of any of items 1 to 22, comprising a composition having the formula: (24) A first film layer, a polylactic acid polymer; a second polymer having a Tg of at least 25°C; A plasticizer, a hydrolysis stabilizer; an inorganic pigment in an amount such that the ratio of polylactic acid polymer to inorganic pigment is less than 4.5:1; The article comprises a first film layer comprising: 25. The article of claim 24, wherein the first film layer comprises a semicrystalline polylactic acid polymer, an amorphous polylactic acid polymer, or a mixture thereof. (26) The article according to item 24 or 25, wherein the article is further characterized by any one of items 2 to 23. (27) A first film layer, a semicrystalline polylactic acid polymer; an optional amorphous polylactic acid polymer; a second polymer having a Tg of at least 25°C; A plasticizer, a nucleating agent; and a first film layer comprising: The film composition has a net melting endotherm ΔH of less than 10 J / g in a first heating scan at a rate of 10° C. / min. nm1 An article having: (28) The article according to item 27, wherein the first film layer further comprises a hydrolysis stabilizer. (29) The article according to item 27 or 28, wherein the first film layer further comprises an inorganic pigment. (30) The article of item 29, wherein the inorganic pigment is present in an amount such that the ratio of polylactic acid polymer to inorganic pigment is less than 4.5:1, 4.4:1, 4.3:1, 4.2:1, 4.1:1, or 4:1. (31) The article according to any one of items 27 to 30, wherein the article is further characterized by any one of items 2 to 23. (32) A first film layer, an amorphous polylactic acid polymer; a second polymer having a Tg of at least 25°C; A plasticizer, a first film layer comprising: The first film layer has a net melting endotherm ΔH of less than 10 J / g in a first heating scan at a rate of 10° C. / min. nm1 An article having: (33) The article according to item 32, further characterized by any one of items 2 to 23 and 28 to 31. (34) A first film layer, a semicrystalline polylactic acid polymer; an optional amorphous polylactic acid polymer; a second (polyvinyl acetate) polymer having a Tg of at least 25°C; A plasticizer, an inorganic pigment in an amount such that the ratio of polylactic acid polymer to inorganic pigment is less than 4.5:1; The article comprises a first film layer comprising: (35) A film layer, a semicrystalline polylactic acid polymer; an optional amorphous polylactic acid polymer; a second polymer having a Tg of at least 25°C; A plasticizer, one or more carbodiimide hydrolysis stabilizers; 10. An article comprising a film layer comprising: (36) The article according to item 34 or 35, further characterized by any one of items 2 to 23 and 28 to 31. (37) A method for producing a graphic film, comprising: Providing a film comprising the first film layer according to any one of items 1 to 36; providing a graphic on said film; A method comprising: 38. The method of claim 37, wherein providing a graphic on the film comprises printing the first film layer with ink. (39) The method according to item 37, wherein the first film layer is annealed before printing. (40) The method according to item 37, wherein the first film layer is unannealed before printing. (41) The first film layer has a net melting endotherm ΔH of less than 10 J / g in a first heating scan at a rate of 10° C. / min. nm1 41. The method according to any one of Items 37 to 40, comprising: (42) The first film layer, when printed, has a net melting endotherm ΔH of less than 10 J / g in a first heating scan at a rate of 10° C. / min. nm1 Item 42. The method according to Item 41, comprising:

Claims

1. a first film layer, a semicrystalline polylactic acid polymer; an amorphous polylactic acid polymer; a polyvinyl acetate polymer having a Tg of at least 25°C; A plasticizer, a hydrolysis stabilizer; an inorganic pigment comprising TiO 2 ; 1. An article comprising a first film layer comprising: the total amount of the semi-crystalline polylactic acid polymer and the amorphous polylactic acid polymer is in the range of 40 to 70 wt %, based on the total amount of the semi-crystalline polylactic acid polymer, the amorphous polylactic acid polymer, the polyvinyl acetate polymer, and the plasticizer; the weight ratio of the amorphous polylactic acid polymer to the semi-crystalline polylactic acid polymer ranges from 2:1 to 4:1; the amount of the polyvinyl acetate polymer is in the range of 15 to 40 wt. % based on the total amount of the semi-crystalline polylactic acid polymer, the amorphous polylactic acid polymer, the polyvinyl acetate polymer, and the plasticizer; the amount of the plasticizer is 5 to 20 wt % based on the total amount of the semi-crystalline polylactic acid polymer, the amorphous polylactic acid polymer, the polyvinyl acetate polymer, and the plasticizer; The amount of TiO2 is such that, when the amount of TiO2 is taken as 1, the total amount of the semi-crystalline polylactic acid polymer and the amorphous polylactic acid polymer is less than 4.5; The article, wherein the first film has a tensile modulus of at least 500 MPa in a standard tensile test using a rate of 600% strain / minute.

2. The article described in claim 1, wherein the amount of TiO2 is at least 15% by weight of the first film layer.

3. 3. The article of claim 1 or 2, wherein the amount of TiO2 is such that the total amount of the semicrystalline polylactic acid polymer and the amorphous polylactic acid polymer is at least 1 when the amount of TiO2 is 1.

4. The article of any one of claims 1 to 3, wherein the hydrolysis stabilizer is a carbodiimide compound.

5. 5. The article of any one of claims 1 to 4, wherein the article is a graphic film, the graphic film further comprising a graphic, the graphic being adjacent to a major surface of the film and comprising a dried and / or cured ink layer.

6. The article of claim 5 further comprising a topcoat layer or cover film disposed over the graphic.

7. The article of claim 6 , wherein the cover film is adhered to the graphic by an adhesive layer.

8. The article of claim 7 , wherein the cover film comprises a semi-crystalline polylactic acid polymer.

9. the first film layer has a net melting endotherm ΔH of less than 10 J / g in a first heating scan at a rate of 10° C. / min. ｎｍ１ The article of any one of claims 1 to 8, comprising:

10. The article of any one of claims 1 to 9, wherein the first film layer is an annealed film or an unannealed film.

11. The article of any one of claims 1 to 10, wherein the article further comprises a backing disposed on a surface facing the film layer, and / or a pressure-sensitive adhesive disposed on an opposing surface of the film layer or the backing.

12. the first film layer has a net melting endotherm ΔH of less than 10 J / g in a second heating scan at a rate of 10° C. / min. ｎｍ２ The article of any one of claims 1 to 11, comprising a composition having:

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