MX2007002754A - Biodegradable paper-based cup or package and production method - Google Patents

Abstract

There is disclosed a biodegradable laminate (10) suitable for use in shaped paper-based articles such as containers for liquid or solid, hot or cool, food products, comprising a paper-based substrate (12) having first and second copolyester layers (14, 16) deposited onto at least one surface of the substrate (12), in the substantial absence of intervening polymer layers between the substrate surface and the copolyesters (14, 16) deposited on the substrate surface. A biodegradable shaped article formed from the laminate (10) and a method for forming a biodegradable laminate are also disclosed.

Description

VESSELS OR PACKAGES BASED ON PAPER BIODEGRADABLES AND METHOD OF PRODUCTION TECHNICAL FIELD This invention relates to laminates based on biodegradable paper. Disposable paper cups for use in food service are typically coated by extrusion with low density polyethylene (LDPE) or other similar polymers, in order to retain liquids for a prolonged period of time, without leakage or that come to soften, as is common in 100% of paper cups. Cups for hot drinks, such as coffee, have a layer of LDPE inside, for resistance to liquid. The glasses for cold drinks for fresh drinks and the like, are coated with LDPE on both sides, to prevent the condensation, which forms on the outside of the glass, from softening the paper. LDPE coatings are common from 12.7 to 38.1 microns weighing 3.266 to 9.798 kg / 278.71 m2). These types of vessels are used once or a very limited number of times, and then discarded. While the paper substrate is typically degradable, the LDPE coating is not readily degradable (and converted into compost), and, therefore, the vessel can remain in the landfills for many years, without decomposing. The use of one or more biodegradable polymers, instead of the LPPE, is convenient to make the used vessels more "environmentally friendly". In addition to glasses, other coated paper products, such as gable cardboard boxes, folded cardboard boxes, paper bags, sandwich wrappers, paper plates and bowls, and ream wrappers, may also benefit from this invention.

PREVIOUS TECHNIQUE Therefore, it is an object of the present invention to provide a biodegradable laminate, suitable for coating paper-based articles, such as containers, which overcome the disadvantages of the prior art materials and methods of this general type, that are biodegradable in a fertilizer environment. It is a further object of the invention to provide a method for forming a biodegradable laminate, suitable for coating articles configured on a paper basis. It is also a further object of the invention to provide a paper-shaped article comprising a biodegradable laminate.

With the above object and others in view, there is provided, in accordance with this invention, a biodegradable laminate, suitable for use in paper-based articles, such as containers for liquid or solid, hot or cold or food products. The biodegradable laminate comprises a paper-based substrate, having two or more surfaces, and which can be deposited on at least one surface of the substrate in at least one layer of a first copolyester and at least one layer of a second copolyester, in the substantial absence of intervening polymer layers, between the surface of the substrate and the first copolyester layer, disposed on the surface of the substrate. A first polyester layer is an inner layer that provides adhesion to the paper-based substrate, and a second copolyester layer is an outer layer that prevents the cooled roller from sticking and blocking in the roller and provides greater thermal stability, compared with the first layer. The first copolyester and the second copolyester are not identical. The copolyester materials of the present invention are copolymerization products of benzene-1,4-dicarboxylic acid with an aliphatic dihydric alcohol, and at least one reagent, selected from the group consisting of an aliphatic dicarboxylic acid and a cyclic dihydric alcohol.

Suitable dihydric alcohols include 1,4-butanediol, 2,2-dimethyl-1,3-propanediol and ethylene glycol. Suitable aliphatic dicarboxylic acids include 1,6-hexanedioic acid, 1,8-nonoanodioic acid, 1,1-decanedioic acid and 1,2-dodecanedioic acid. Suitable cyclic dihydric alcohols include cyclohexane-1, 4-dimethanol, 1,1,3,3-tetramethylcyclobutane-2,4-diol and 1,4: 3,6-dianhydro-D-sorbitol. A first copolyester, particularly preferred, is a copolymerization product of benzene-1,4-dicarboxylic acid with atypical acid and 1-butanediol. This product is commercially available under the trade name of ECOFLEX and EASTAR BIO. A second copolyester, particularly preferred, is a product of the copolymerization of benzene-1,4-dicarboxylic acid with ethylene glycol and 1,4: 3,6-dianidro-D-sorbitol. This product is commercially available under the trade name of BIOMAX. A particularly preferred way of depositing the layers of the copolyester is by coextrusion, suitably on a moving cardboard web. The copolyester materials of the present laminate have been certified as biodegradable in a compost environment (as tested by ASTM D6400-99) which makes the laminate highly convenient as a material for use in forming commonly used food containers. only once, or a limited number of times, before disposal. Similarly, the biodegradability of the present laminate makes it useful in other "single-use" paper-based products, such as sandwich wrappers, ream wrappers, etc. In one embodiment, the present laminate may be provided with a co-extruded layer of the same or other copolyesters on the opposite surface of the paper-based substrate. Also provided, in accordance with this invention, is a paper-based, biodegradable shaped article, such as a biodegradable container or preform or semi-finished intermediate, capable of being formed into a container, formed of the biodegradable laminate. Also, according to this invention, there is provided a method for forming a biodegradable laminate, suitable for use in paper-based articles. Other features that are considered peculiar to the invention are pointed out in the appended claims. Although the invention is illustrated and described as embodied in a paper-based, biodegradable vessel or package, it does not intend to be limited to the details shown, since various modifications and structural changes can be made without departing from the spirit of the invention and within the scope or scope of the equivalents of the claims. The construction and method of operation of the invention, however, together with additional objects and advantages thereof, will be better understood from the following description of the specific embodiments, when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figures 1 and 2 are schematic perspective views, representing a laminate embodiment incorporating various features of the present invention; Figure 3 is a schematic representation of a second embodiment of a laminate incorporating various features of the present invention; and Figure 4 is a schematic representation of a process for the formation of a laminate of the present invention.

THE BEST WAY TO CARRY OUT THE INVENTION Referring now to the figures of the drawing in detail and first, particularly, to Figures 1 to 3, there is shown a biodegradable laminate 10, which is paper based, which means that the substrate 12 of the laminate comprises paper, commonly a paper-based material, known as SBS cup material or strong US (natural) folded cardboard board, all of which are known in the art. The laminate of the present invention further includes first and second layers 14 and 16, respectively, of copolyesters which are co-extruded on one of the surfaces of the paper-based substrate. As illustrated in Figure 4, the formation of the laminate of the present invention includes feeding a continuous sheet of SBS or other acceptable substrate, paper based, from a roll 22 thereof, forward in a conventional co-extruder 24. , which feeds a first copolyester 26 and a second copolyester 28. The first and second copolyesters are co-extruded onto the flat surface 18 of the paper-based substrate and then collected, as by rolling the complete laminate 30 on an axis 32 or similar. Next, the laminate can be formed in a glass, bag, gable top container or other container, for a food product, suitably by first obtaining a preform or intermediate product and converting it into a finished article. The container, thus formed, is useful for containing a liquid, solid or semi-solid food product, regardless of whether this food product is cold or hot (within the normal temperatures of the heated or cooled food products). An example of a hot food product is coffee stir at approximately 82 ° C. An example of a cold food product is ice tea at 0.55 to -4.44 ° C. In a preferred embodiment, the paper-based substrate of the laminate of the present invention comprises the SBS cup material (solid bleached sulphate) or folded cardboard board (natural, strong) (solid bleached sulfate) the preferred range of thicknesses of the Board vary between approximately 45.4 to 136 kg / 278.71 m2. Other examples of an acceptable base material (substrate) include the liquid packing board. SBS folded cardboard board, strong, natural cup material, strong paper or lightweight SBS, and board or paper with waste content after consumption ("recycled"). The papers of that light are defined as less than 45.4 kg / 278.71 m2. The packaging board for liquids can be used for cardboard boxes with gable top, in products such as dairy, for example. Uses of lightweight papers include bags for powders or other dry products, such as oatmeal, sandwich wrappers for fast service restaurants, and ream wrappers for copy paper. In accordance with one aspect of the present invention, as illustrated in Figures 1 and 2, a co-extruded combination of a copolyester, i.e., any copolyester produced, is applied to at least one flat surface of the paper-based substrate. of the copolymeation of benzene-1,4-d-carboxylic acid (terephthalic acid), 1,3-butanediol and atypical acid, as well as an entangling agent or chain brancher (available from BASF ba or the name EOFLEX®, which has a melting point that varies from 100 to 10 ° C or a copolyester produced from the copolymerization of acid 1, 3-benzenedicarboxylic acid (terephthalic acid), 1,4-butanediol and atypical acid (the resulting copolyester being poly (tetramethylene-co-terephthalate adipate) (available from Eastman Chemical / Novamont ba or name of Eastar Bio®, which has a melting point of 108 ° C and a copolyester produced by the condensation reaction of benzene-1,4-carboxylic acid, ethylene glycol and 1,4: 3, 6-d ? anhydro-D-sorbitol (available from DuPont under the name Biomax®, which has a melting point of 195 ° C.) As illustrated in Figure 1, in a preferred embodiment for use with containers For hot food products, a substrate, based on paper, is provided on a flat surface, with a co-extruded layer of Ecoflex and Biomax, individually in a fertilizer medium, about 90% of Ecoflex resin is biodegraded within approximately 80 days and about 95% of the Biomax resin biodegrades within about 63 days. At the University Lab, more than 90% of the coated laminate is biodegraded in about 88 days, meeting the criteria for biodegradability / composting, in accordance with ASSTM D6400-99 and D6868 standards. In this preferred embodiment for hot food containers, a total co-extrusion coating weighs between about 4.54 and 18.14 kg / 278.71 m2, in any combination of about 80/20 to 20/80 parts by weight of Ecoflex to Biomax can be employed A total coating weight of 11.34 / 278.71 m2 is preferred for both processability and end-use performance. Preferably, the Biomax is applied between 2.27 to 9,072 kg / 278.71 m2 The remainder of the total coating weight being Ecoflex. For a glass of hot beverage, for example, co-extrusion is applied to the coated side of the paper-based substrate. The pre-treatment of flame and / or corona of the substrate surface can be employed to increase adhesion, as desired or necessary. Lighter coating weights may be used, but there is a possible loss of the heat seal output, in subsequent finished packages (beakers, containers with table tops, etc.) The heavier total coating weights may also be used , but material costs may import more than any incremental performance advantage of such heavier total coating weights and / or may decrease the overall degradation rate of the container. In addition, it has been found that the use of Ecoflex as a single layer in a laminate for biodegradation purposes typically requires slip additive / anti-block packages to prevent the cold roll from sticking and blockage in the roll of the finished laminate. In addition, a considerable reduction in the neck is experienced with one or more copolyesters, when applied as a monolayer, resulting in excessive cutting and waste. The Biomax, in particular, when applied as a single layer, does not adhere satisfactorily to the paper-based substrate. In contrast, the use of a combination, according to this invention, of the aforementioned copolyesters has been found effective in overcoming the drawbacks of copolyesters when applied as a single layer.

Containers for cold food products are preferably formed from a laminate, as illustrated in Figure 3. This illustrated laminate includes a paper-based substrate, having a first layer of Eastar Bio or Ecoflex co-extruded (preferably Ecoflex ) and Biomax on a flat surface of the substrate, the Biomax being disposed further to the outside of the substrate, in addition, a second layer of Eastar Bio or Ecoflex co-extruded (preferably Ecoflex) and Biomax is provided on the opposite flat surface of the substrate, the Biomax again being more disposed to the outside of the substrate. In this embodiment for cold food containers, the co-extruded layer of the copolyester (regardless of which side of the substrate of the layer is disposed) is of a total coating between about 80/20 to 20/80 parts by weight of Ecoflex to the Biomax . A total coating weight of 11.34 kg / 278.71 m2 is preferred. As in the laminate intended for use with the hot food product, in this laminate intended for use with the cold food product, the Biomax is applied at a coating weight between approximately 2.27 and 9,072 kg / 278.71 m2. the rest of the weight of the total coating being either Ecoflex or Rastra Bio.

In a further embodiment, as illustrated in Figure 1, the paper-based substrate 12 can be provided with a co-extruded layer of Eastar Bio 14 and Biomax 16 on one of the flat surfaces of the substrate. In this mode, the weight of the total coating is between 4.54 and 18.14 kg /278.71 m2, in any combination between 80/20 and 20/80 parts by weight of Eastar Bio to Biomax can be used. A total coating weight of about 11.34 kg / 278.71 2 is preferred. A Biomax applied to a coating weight between 2.27 and 9,072 kg / 278.71 m2, this is the total weight of the coating being from Eastar Bio. As desired, calcium carbonate can be added to any or all of the copolyester extrusions, as a cost-saving measure and to provide an increase in the rate of degradation by the displacement of some of the biodegradable resin material. Other possible organic and inorganic fillers can be used with, or in place of, calcium carbonate, which includes starch, clay, kaolin, talcum, cellulose fibers and diatomaceous earth. A two-layer co-extrusion coating, consisting of BASF Ecoflex and DuPont Biomax, was applied to the SBS cup material and strong, natural folded cardboard boards, SBS base weights and strong paper were in the range of 81.65 to 95.26 / 278.71 m2. The melting process temperatures of the two resins were from 232 to 240 ° C. The coating weights applied were 5.67 kg / 178.71 m2 of Ecoflex and 5.67 kg / 278.71 m2 to 11.34 kg / 278.71 m2 providing good melting strength and minimal edge fabric of the co-extrusion curtain. The preforms and intermediate materials having a co-extruded biodegradable laminate in the SBS cup material and the SUS folded cardboard board, produced as noted above, are converted into cups in a PMC 1000 cup form machine at a rate of 140. glasses per minute, all glasses passed the coffee-retaining test (at 92 ° C) for at least 25 minutes, without escaping, coating softening or visual contamination of the beverage by the coating. The heat seal test was conducted on standard polyethylene LDPE coated cup material, and Kraft folded cardboard materials, on which the Ecoflex and Biomax were co-extruded. for each substrate, the samples were placed with the coated side to the uncoated side in a Barber-Coleman sealing unit. The sealing pressure was varied to determine the minimum temperature at which 100% fiber tear was obtained. Following the sealing step, samples were allowed to retreat for 30 seconds, before manually pulling the layers apart and visually evaluating the extent of fiber tearing. For the standard cup material, coated with LDPE, the minimum sealing temperature was 104 ° C. The strong Kraft paper board, coated with Ecoflex and Biomax, the seal is at a minimum temperature slightly lower than 100 ° C. In accordance with one aspect of the present invention, it is noted that the co-extrusion of the two copolyesters provides multiple benefits. For example, Easter Bio and Ecoflex adhere well to paper, resulting in a 100% fiber tear. On the other hand, the level of adhesion between Biomax and paper is much lower, resulting in very little fiber tear. Thus, in the present invention, an Eastar Bio or Ecoflex layer of the co-extrusion is disposed directly adjacent to the cardboard substrate, to gain good adhesion. The Biomax is less sticky than any of the Easter Bio or Ecoflex. Therefore, a Biomax layer of the co-extrusion is disposed more to the outside of the layers of the laminate to prevent the laminate from sticking to the cold roll and to prevent blockage of the laminate on the roll. Also, the Biomax has a significantly higher melting point than either Eastar Bio or Ecoflex (Tm = 195 ° C for Biomax vs 197, 7 ° C for Easter Bio and 100 -120 ° C for Ecoflex), so the placement of the Biomax as the outermost layer of the laminate, in contact with the hot food product, allows the formed container of the laminate to better support the deterioration and softening of the coating by the hot food product.

Claims (19)

1. CLAIMS A biodegradable laminate, comprising a paper-based substrate, having laminated at least one layer of a first copolyester and at least one layer of a second copolyester, said layers being deposited on at least one surface of said substrate, wherein the first layer is an inner layer, which provides adhesion to the paper-based substrate, and a second layer is an outer layer, which prevents the cold roll from sticking and blocking the roller and provides greater thermal stability, as compared to said first layer. cap.
2. The biodegradable laminate of claim 1, wherein the copolyesters of said first and second layers are non-identical copolymerizable products of the acid-benzene-1, -dicarboxylic acids and with an aliphatic dihydric alcohol and at least one reagent, selected from the group consisting of an aliphatic dicarboxylic acid and a cyclic dihydric alcohol.
3. The biodegradable laminate of claim 2, wherein said dihydric alcohol is 1,4-butanediol and said at least one reactant is 1,6-hexanedioic acid.
4. The biodegradable laminate of claim 2, wherein said dihydric alcohol is ethylene glycol and said at least one reagent is 1,3: 3,6-dianhydro-D-sorbitol.
5. The biodegradable laminate of claim 1, wherein the copolyesters of said first and second layers are non-identical copolymerization products of benzene-1,4-dicarboxylic acid with an aliphatic dihydroxy alcohol, and at least one reagent selected from the group consisting of an aliphatic dicarboxylic acid and an aromatic dihydroxy alcohol.
6. The biodegradable laminate of claim 1, wherein said copolyester layers have different melting points, and the lower melting copolyester is disposed between said substrate and the higher melting copolyester.
7. The biodegradable laminate of claim 1, wherein the proportions of the first copolyester and the second copolyester vary from 20 parts by weight of said first copolyester to 80 parts by weight of said second copolyester, up to 80 parts by weight of said first copolyester to 20. parts by weight of said second copolyester.
8. The biodegradable laminate of claim 1, wherein the total coating weight of said first and second copolyesters is in a range of about 4.54 to about 18,144 kg / 278.71 m2.
9. The biodegradable laminate of claim 8, wherein the weight of the total coating of the first and second copolyesters is 11.34 kg / 278.71 m2.
10. The biodegradable laminate of claim 1, wherein an inorganic filler is added to at least one copolyester layer.
11. The biodegradable laminate of claim 10, wherein the inorganic filler is calcium carbonate.
12. The biodegradable laminate of claim 1, wherein the copolyester layers can be heat sealed.
13. The biodegradable laminate of claim 1, configured to be biodegradable, according to the criteria for biodegradability / composting, as specified in the ASTM D6400-99 and D6969 standards.
14. A shaped, biodegradable, paper-based article comprising a paper-based substrate, having at least two surfaces and a biodegradable laminate provided on at least one surface of said substrate, wherein said laminate has an inner layer of a first copolyester laminated to the same, said first copolyester layer provides adhesion to the paper-based substrate, and an outer layer of a second copolyester, which prevents sticking of the cold roll and blocking in the roll and provides greater thermal stability, compared to said roll. first layer, and in which the copolyesters of said first and second layers are non-identical copolymerization products of benzene-1,4-dicarboxylic acid with an aliphatic dihydric alcohol and at least one reagent, selected from the group consisting of an aliphatic dicarboxylic acid and a cyclic dihydric alcohol.
15. The biodegradable shaped article of claim 14, wherein said paper-based substrate has a layer of said first and second copolyesters provided on a surface of the substrate, and a second layer of said first and second copolyesters is provided on the composite surface of said substrate. substrate
16. 16. The biodegradable shaped article of claim 14, wherein said substrate, based on paper, has a layer of said first and second copolyesters, provided on a surface of said substrate, and the opposite surface of said substrate is without coat.

    17. The biodegradable shaped article of claim 14, having a configuration selected from the group consisting of cups, cardboard boxes with gable top, folded cardboard boxes, paper bags, sandwiches, plates and paper bowls, ream wrapping and preforms for its manufacture.

    18. The biodegradable shaped article of claim 14, wherein it is a preform for use in prodg a cup for cold food products.

    19. The biodegradable shaped article of claim 14, wherein it is a vessel for cold food products . A bag, cardboard box with gable top, or other container, for food products and not food, liquid, solid or semi-solid, constructed of a laminate, according to claim 15. . A package wrap, constructed of a laminate, according to claim 15. . A method for forming a paper-based biodegradable shaped article, this method comprises the following steps: a) providing a substrate, based on paper, having a basis weight in the range of 45.36 to 136.08 kg / 278.71 m2 and minus a flat surface; b) applying to this at least one surface of the substrate a laminate of at least one first copolyester and at least one second copolyester, the first copolyester and the second copolyester are not identical; and c) configure the article; wherein a layer of the first copolyester is an inner layer that provides adhesion to the paper-based substrate, and a layer of the second copolyester is an outer layer that prevents sticking of the cold roll and blocking on the roll, and provides greater stability thermal, compared to the inner layer, and wherein the first and second copolyesters are non-identical copolymerization products of benzene-1,4-dicarboxylic acid with an aliphatic dihydric alcohol and at least one reagent, selected from the group consisting of a dicarboxylic acid aliphatic and a cyclic dihydric alcohol. . The method of claim 22, wherein the first and second copolyesters with non-identical copolymerization products of 1,4-dicarboxylic acid with an aliphatic dihydroxy alcohol, and an aliphatic dicarboxylic acid or an aromatic dihydroxy alcohol forming a reagent. . The method of claim 22, wherein the total coating weight is in the range of about 4.64 to about 18.14 kg /

    278. 71 m. . The method of claim 22, wherein the first and second copolyesters have different melting points, and the copolyester with lower melting point is deposited between the substrate and the copolyester with higher melting point. . The method of claim 22, wherein a layer of copolyesters is applied to a surface of the substrate and a second layer of copolyesters is applied to the opposite surface of the substrate. The method of claim 22, wherein a layer of copolyesters is applied. to a surface of the substrate and the opposite surface of said substrate is uncoated. The method of claim 22, wherein these at least two copolyesters are applied to the substrate by coextrusion, together on a moving web of paper or cardboard. The method of claim 28, wherein the temperatures of the extrusion melt for the first and second layers of the copolyester are in the range of 226.7 to 265.5 ° C.