IMPROVEMENT IN WATER-VAPOR BARRIER PROPERTIES IN FOLDABLE MATERIALS

Abstract

Provided is a non-metalized blank having superior barrier properties and processes for maintaining such properties.

Claims

1.-56. (canceled)

57. A non-metalized blank having at least one mechanically induced folding pattern, the blank comprising or being formed of at least one hydrophobic material and having a water vapor transmission rate (WVTR) that is between 1 and 20 gr/m.sup.2. day, when measured at 38 C. and 90% relative humidity, at any point along the blank surface, including at the folding pattern, wherein the at least one hydrophobic material is selected from at least one wax, at least one modified wax, latex and mixtures thereof.

58. The blank according to claim 57, having at least one mechanically induced folding pattern and comprising at least one hydrophobic material selected from at least one wax, at least one modified wax, latex and mixtures thereof, the at least one hydrophobic material endowing said blank with a water vapor transmission rate (WVTR) between 1 and 20 gr/m.sup.2.Math.day, when measured at 38 C. and 90% relative humidity, wherein the WVTR is substantially the same throughout the blank surface, including at the folding pattern.

59. The blank according to claim 57, wherein the blank is a polymeric blank, a paper or paper-based blank, a polymer coated paper-based blank, a nanocellulose blank, a nanocellulose/polymer blank, a fabric-based blank, or a porous blank.

60. The blank according to claim 59, wherein the paper-based blank or coated paper-based blank is a paperboard.

61. The blank according to claim 59, wherein the blank is a polymeric blank composed of a polymeric material.

62. The blank according to claim 61, wherein the polymeric material is selected from polyethylene, polypropylene, polyvinyl alcohol, ethylene vinyl alcohol, polyamide, polystyrene, polylactic acid, polyhydroxyalkanote, polycaprolactone, polyhydroxybutyrate, polyvinyl acetate, polyacrylonitrile, polybutylene succinate, polyvinylidene chloride, starch, cellulose, polyhydroxyvalerate, polyhydroxyhexanoate, polyanhydrides, polyethylene terephthalate, polyvinyl chloride and polycarbonate.

63. The blank according to claim 61, wherein the polymeric material is polyester.

64. The blank according to claim 61, wherein the polymeric material is selected from polyethylene, polypropylene, polyester, polyvinyl alcohol, ethylene vinyl alcohol, polyamide, polystyrene, polylactic acid, polyhydroxyalkanote, polycaprolactone, polyhydroxybutyrate, polyvinyl acetate, polyacrylonitrile, polybutylene succinate, polyvinylidene chloride, starch, cellulose, polyhydroxyvalerate, polyhydroxyhexanoate, polyanhydrides, polyethylene terephthalate, polyvinyl chloride and polycarbonate, or any blend of two or more thereof.

65. The blank according to claim 59, wherein the blank is a paper blank or a paper-based blank.

66. The blank according to claim 57, being in a form of a multilayered structure, wherein the layer or film of the at least one wax, at least one modified wax, latex or mixtures thereof forms a layer in the multilayered structure.

67. The blank according to claim 57, wherein the blank comprises the at least one wax, or the at least one modified wax, and wherein the at least one wax, or at least one modified wax is mixed in the blank composition or is provided as a film on the blank.

68. A process for manufacturing a blank or a packaging material having at least one folding or creasing pattern, the process comprising forming a blank or a packaging material comprising at least one wax, at least one modified wax and/or latex, said blank having preselected barrier properties; and mechanically forming said folding or creasing pattern on a surface region of the blank or a packaging material, wherein following the mechanical forming of the pattern, the preselected barrier properties are maintained throughout the surface of the blank or packaging material, including at the folding or creasing pattern.

69. A process for maintaining at least one barrier property of a blank or a packaging material having preselected barrier properties at a time prior to forming a folding or creasing pattern in the blank or packaging material, the process comprising forming a blank or a packaging material comprising at least one wax, at least one modified wax and/or latex, the blank or packaging material having preselected barrier properties, and mechanically forming said folding or creasing pattern, wherein subsequent to the mechanical forming of the pattern, the preselected barrier properties are maintained throughout the surface of the blank or packaging material, including at the folding or creasing pattern.

70. A process for minimizing or diminishing transmission of water vapors through a folding or a creasing pattern imposed in a blank or a packaging material by compression or creasing, the process comprises forming a blank of a packaging material comprising at least one wax, at least one modified wax and/or latex, said blank having a preselected water vapor barrier property and mechanically forming a folding or a creasing pattern, wherein subsequent to the mechanical forming of the pattern, the preselected barrier property is maintained throughout the surface of the blank or packaging material, including at the folding or creasing pattern.

71. The process according to claim 61, wherein the barrier property is WVTR.

72. The process according to claim 61, wherein the preselected barrier property is achievable by: (i) mixing the at least one wax, the at least one modified wax, the latex or mixtures thereof with a blank composition in a process for manufacturing the blank; or (ii) forming a layer or a film of the at least one wax, the at least one modified wax or the lates or mixtures thereof on a surface of a blank absent of the preselected barrier property.

73. The process according to claim 61, wherein the at least one wax, at least one modified wax, latex or mixtures thereof is provided in a formulation or an emulsion further optionally comprising at least one additive.

74. A non-metalized packaging material formed of a non-metalized blank, the packaging material having one or more panels or faces foldable along at least one mechanically induced folding pattern, the packaging material having a water vapor transmission rate (WVTR) that is substantially constant throughout the material surface including at the folding pattern, wherein the blank comprises or is formed of at least one hydrophobic material selected from at least one wax, at least one modified wax, latex and mixtures thereof.

75. The blank according to claim 57, being a paper-based blank comprising a sheet of a dry pulp composition and a layer of the at least one hydrophobic material.

76. The blank according to claim 57, being a paper-based blank comprising a sheet of a dry pulp composition and the at least one hydrophobic material and a layer of the at least one hydrophobic material, wherein the at least one hydrophobic material present in the pulp composition and the at least one hydrophobic material present in the layer are same or different.

Description

DETAILED DESCRIPTION OF EMBODIMENTS

Experimental

[0180] EVA modified Paraffin synthesis: Paraffin, and EVA were melted together at 90 C. The mixture was stirred at 800 RPM using a propeller stirrer, until homogeneous mixture was obtained.

[0181] Emulsion preparation: Two emulsification systems were tested. Both systems were formulated in a hot water bath (80 C.)

System 1

[0182] a. Modified paraffin and emulsifier mixtures were stirred at 250 RPM. [0183] b. Hot water was added in intervals until a total amount of desired water was added. During the water addition the mixture was stirred at 800 RPM. [0184] c. During the addition of water, W/O emulsion was created. At a certain amount of water, the viscosity drops, and an O/W emulsion was created. [0185] d. Optionally, the emulsion may be sonicated for 30 s. [0186] e. The resulted suspension was a white, stable water suspension.

System 2

[0187] a. Modified paraffin and stearic acid, as emulsifier, were stirred at 250 RPM. [0188] b. After clear melt was obtained, hot water was added in intervals until total amount of desired water was added. During the water addition the mixture was stirred at 800 RPM. [0189] c. After the addition of water, TEA (triethanolamine) was added. The mixture then became completely white. [0190] d. Cooling the emulsion to around 30 C., at which temperature stirring was stopped. [0191] e. The resulted suspension was a white, stable water suspension.

Characteristics

[0192] The emulsions were found stable and slight sedimentations could be fixed with short mixing. The viscosity of the emulsions was between 100 and 1000 cPs. Also, the emulsions could be coated using conventional coating machinery (gravure, flexo, slot-die, rod, etc.) and by using spray and dip coating on a variety of substrates.

Coating:

[0193] Both emulsions were applied, using a rod coater, on different papers, precoated with an OTR barrier layer(s) and on uncoated papers. The coating thickness varied between 12 and 40 um (wet). The paper was then dried for 15 min in 90 C.

[0194] The resulting dry coating weight was between 1-8 g/m.sup.2. Water vapor permeability was as followed: [0195] All paper samples were tested according to known standards (ASTM F1249-13 and F3299-18) at 90% RH and 38 C. [0196] WVTR results are as described in Table 1

Preparation of a Barrier Emulsion With 40 wt %

[0197] PE modified paraffin wax was melted together with stearic acid (10% of the wax) at 75 C. under continuous stirring. Thereafter, hot water was added in intervals, following by addition of KOH until a pH of 8 was reached.

[0198] The emulsion was then cooled to 50 C. 40% modified wax emulsion was mixed with 40% latex emulsion at a ratio of 1:2 to obtain a stable, white suspension.

Preparation of a Barrier Emulsion With 35 wt % and High Sustainable Material Content

[0199] EVA modified vegetable wax was prepared by reacting the wax with EVA in a similar way as the preparation of EVA modified paraffin wax. EVA modified vegetable wax was melted together with carnauba wax and oleic acid (30% of the wax). Hot water was then added in intervals, followed by the addition of triethanolamine (3% of all solids).

[0200] The emulsion was subsequently cooled to 50 C. and 40% wax emulsion was mixed with 40% latex emulsion at a ratio of 1:3 and water and lignin were added in order to reach a solid content of 35%.

[0201] The final sustainable materials content in the emulsion was 40%.

Preparation of a barrier emulsion with 40 wt % and 51% renewable content:

[0202] Wax based emulsion was mixed with soy wax-based emulsion with 1:1 ratio (solid content wise). The soy wax emulsion contains 100% renewable material. Water was added to get 40 wt %. the final emulsion contains 51% renewable content

Coating Paper With crease

[0203] Paper with and without an OTR layer were coated with different formulation of the invention. After drying for 15 min in 90 C., the coated papers were creased, using a creasing device. Creased samples were evaluated for their WVTR performance, and it was shown that the WVTR results remained the same as shown in Table 1 (15 g/m.sup.2*day). In addition, testing for oil penetration, it was observed that coating of paper with suspensions of the invention lead to significantly lower penetration of oil after creasing.

Applications

[0204] The modified wax/latex barrier formulation with a viscosity of 150 cP and a solid content of 40% was applied on a kraft paper reel that was previously coated with an OTR layer. The application was conducted using a gravure printing machine. The coating speed was 100 m/min and the wet coating weight was 12 g/m.sup.2. The coated paper was dried at 120 C. and the resulted dry coating weight was 5 g/m.sup.2.

[0205] The resulting paper showed excellent water vapor barrier performance (WVTR=11 gr/m.sup.2/day @ 38 C., 90% RH) and oxygen barrier performance (OTR=2.3 ml/m.sup.2/day @ 23 C., 70% RH). It also showed very low water absorption (COBB60 =0.6 g/m.sup.2) and high oil resistance (KIT 12).

[0206] Manufacturing of paper blanks: Bleached or unbleached pulp is prepared and may be further refined to cut the fibers and roughen the surface of the fibers to enhance formation and bonding of the fibers as they enter the paper machine. Water is added to the pulp slurry to make a thin mixture normally containing less than 1% fiber. At this stage it is possible to add a formulation of the invention. The dilute slurry is then cleaned in cyclone cleaners and screened in centrifugal screens before being fed into the wet end of the paper-forming machine (it is being dewatered). After this stage it is also possible to add the formulation.

[0207] From this stage the slurry undergoes the final processing, determining whether the product will be paper or pulp tissue for molding/other pulp uses. A formed pulp tissue can be sprayed with the formulation before molding, creating barrier in the substrate. Final weight of the formed substrate (paper/pulp mold) may vary between 30-1000 (g/m.sup.2).

[0208] Molding process: The molding process of pulp to obtain molded products is mainly through a series of methods such as vacuum molding and grouting molding, so that the raw pulp fibers are formed into the shape designed by the mold, and vacuum molding is the most commonly used and most effective one. The drying process mainly uses fuel, oil, gas, electricity or steam, heat transfer oil or other media as a heat source, heating air, drying the pulp molded products in the hot air, and extracting evaporated water from the products through a fan accelerates the drying effect. After the pulp product is shaped and dried, it is basically shaped, and then heated with an electric heating plate or other heating medium (such as heat transfer oil) to make the pulp product mold have a higher temperature (150-250 C.), and then use air pressure or hydraulic pressure, thus the paper support product is pressed under high temperature and high pressure to make the product appearance neat and beautiful, achieve better toughness, and make it have better shock resistance.

[0209] Alternatively to molding, other techniques may be used for preparing products of the invention may be or may include various deposition methods, structuring methods and film forming methods. Injection molding or other injection techniques are exemplary alternative methods.

Example 1

[0210] Oxygen barrier formulation was added to a pulp mixture of 80% hardwood/20% softwood pulp10% of the pulp weight. Cationic starch was added as a retention aid. The formula was added to the first stage of the pulp mixture, before dewatering of the mixture. Assumingly in this stage the loading of the formula onto the cellulosic fibers should be best. The paper making procedure was continued until a final paper was produced. The paper weight was 90 g/m.sup.2, and the resulting paper showed oxygen barrier performance (OTR=10 ml/m.sup.2*day @ 70% RH)

Example 2

[0211] Water vapor barrier formula was added to a pulp mixture of 75% hardwood/25% softwood pulp15% of the pulp weight. The formula was added to the first stage of the pulp mixture, before dewatering of the mixture. The paper making procedure was continued until a final paper was produced. The paper weight was 65 g/m.sup.2, and the resulting paper showed water barrier performance (WVTR=25 ml/m.sup.2*day @ 90% RH, 38 C.) and also reduced water absorption compared to neat paper (COBB60=10 gr/m.sup.2).

Example 3

[0212] Oxygen barrier formulation was added to a pulp mixture of 80% hardwood/20% softwood pulp10% of the pulp weight. Cationic starch was added as a retention aid before formula addition. The formula was added to the first stage of the pulp mixture, before dewatering of the mixture. Assumingly in this stage the loading of the formula onto the cellulosic fibers should be best. The pulp mixture was molded in a wet formed fiber process, to produce complex structures such as trays and paper bottles. The molded pulp showed oxygen barrier performance (OTR=10 ml/m.sup.2*day @ 70% RH), and its weight was 200 g/m.sup.2.