TW201300229A - Disposable lid having polymer composite of polyolefin and mineral filler - Google Patents

Abstract

Disposable lid comprises a thermoformed sheet in the shape of a lid for a hot beverage container. The sheet comprises a polymer composite of a polyolefin and at least one mineral filler. The sheet has a thickness less than about 0.035 inches and a heat deflection temperature at least comparable to that of high impact polystyrene.

Description

No-clean cover for polymer compositions with polyolefin and mineral fillers

This application is generally directed to polymer compositions that are particularly suitable for disposable covers and such materials. Specifically, the present application relates to a disposable cover comprising a thermoformed sheet having a polymer composition consisting of a polyolefin and at least one mineral filler.

This application claims the benefit of priority to U.S. Provisional Application Serial No. 61/477,886, filed on Apr. 21, 2011, the entire disclosure of which is incorporated herein by reference.

Hot beverages such as coffee that is cooked for busy people are typically served in thick paper cups with disposable lids. The coffee is usually cooked at 90 ° C to 96 ° C, maintained at 82 ° C to 88 ° C and supplied at 70 ° C to 80 ° C. The coffee cup cover preferably has mechanical strength to withstand the force required to push the lid onto the cup and maintain dimensional stability at the temperature of the coffee. The mechanical strength of the material over a range of temperatures can be related to the material's heat distortion temperature ("HDT") or the deformation temperature under load ("DTUL"). The current closure materials for hot beverage cups are primarily made of impact resistant polystyrene ("HIPS"), which is easy to handle due to its amorphous structure and has a good balance between stiffness and strength. However, impact polystyrene resins may be susceptible to chemical attack and fragmentation by solvents. In addition, the presence of residual styrene monomer in the resin can cause annoying odors. In addition, impact-resistant polystyrene resins have a relatively high carbon footprint among all commercial grade resins. Therefore, there is still a need to make improved disposable covers.

The objects and advantages of the present invention will be apparent from the following description of the present invention. Additional advantages of the present application can be realized and achieved by the means particularly pointed out in the written description.

In order to achieve such and other advantages as embodied and broadly described, and in accordance with the purpose of the present application, the present application includes a disposable cover comprising a thermoformed sheet in the form of a lid for a hot beverage container. The sheet comprises a polymer composition consisting of a polyolefin and at least one mineral filler. The sheet has a thickness of less than about 0.035 inches and the heat distortion temperature is at least comparable to the heat distortion temperature of the impact resistant polystyrene.

According to one aspect, the heat distortion temperature can be at least about equal to the heat distortion temperature of the impact resistant polystyrene. Specifically, the heat distortion temperature may be about at least 87 ° C according to ASTM D648-06 Standard Test Method (2006), which is subjected to the deformation temperature of the edge position of the plastic under a bending load.

As embodied herein, the mineral filler can comprise a high aspect ratio mineral filler, for example, a mineral filler selected from the group consisting of talc, mica, ascite, or combinations thereof. For example, the polymer composition can include about at least 10% by weight of the high aspect ratio mineral filler. Additionally or alternatively, the mineral filler may comprise a low aspect ratio mineral filler, such as calcium carbonate. For example, the polymer composition can include at least about 20% by weight of the low aspect ratio mineral filler. The polyolefin may be selected from the group consisting of a polypropylene homopolymer, a polypropylene impact copolymer, an ethylene-propylene random copolymer, a high density polyethylene, or a combination thereof.

In one embodiment, the polyolefin comprises polypropylene, the mineral filler comprises a high aspect ratio mineral filler, and the polymer composition comprises at least about 10% by weight mineral filler. In another embodiment, the polyolefin comprises polypropylene, the mineral filler comprises a low aspect ratio mineral filler, and the polymer composition comprises at least about 20% by weight of the mineral filler. In yet another embodiment, the polyolefin comprises high density polyethylene, the mineral filler comprises a high aspect ratio mineral filler, and the polymer composition comprises about at least 20% by weight of the mineral filler. In yet another embodiment, the polyolefin comprises high density polyethylene, the mineral filler comprises a low aspect ratio mineral filler, and the polymer composition comprises about at least 40% by weight of the mineral filler.

According to another aspect, the polyolefin can comprise polypropylene, the mineral filler can comprise a high aspect ratio mineral filler, and the shrinkage of the polymer composition can be comparable to the shrinkage of impact polystyrene. For example, the polymer composition may have a shrinkage of from about 0.5% to about 1.0% as measured according to the ASTM D955 standard (1996). In this manner, the polymer composition comprises from about 20% to about 40% by weight of the mineral filler.

According to another aspect, the polyolefin can comprise polyethylene, the mineral filler can comprise a high aspect ratio mineral filler, and the shrinkage of the polymer composition can be comparable to the shrinkage of polypropylene. Thus, the polymer composition can have a shrinkage of from about 1.25% to about 1.75% when measured according to the ASTM D955 standard (1996). In this embodiment, the polymer composition comprises from about 30% to about 50% by weight of the mineral filler.

According to one aspect of the disclosed subject matter, the polymer composition is mainly composed of The polyolefin consists of at least one mineral filler. However, the polymer composition may further comprise a group selected from the group consisting of color formers, processing aids, and combinations thereof.

As embodied herein, the hot beverage container can be a coffee cup, but a cover for other suitable containers is also envisioned.

According to another aspect, the carbon footprint of the polymer composition can be lower than the carbon footprint of the impact resistant polystyrene. For example, the polymer composition may have a lower greenhouse gas emissions than the greenhouse gas emissions of the impact resistant polystyrene.

The above general description and the following detailed description are intended to be illustrative and are intended to provide further explanation of the claimed application.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in this specification, are in FIG The drawings, together with the written description, are used to explain the principles of the application.

Reference will now be made in detail to the preferred embodiments embodiments The disposable cover presented herein is generally intended for use with a cup or other container containing a high temperature beverage, such as coffee. Although reference will be made herein to the cover for a hot beverage cup, other similar or suitable uses are envisioned.

Generally, polyolefins have a heat distortion temperature lower than that of impact polystyrene ("HIPS") and are therefore not suitable for use as a cover material for a hot beverage cup alone (i.e., as a pure material). However, according to the disclosed subject matter, the heat distortion temperature of the polyolefin can be improved by adding at least one mineral filler to form a polymer composition. Polymer synthesis obtained The heat distortion temperature of the article can be at least about equal to the heat distortion temperature of the impact resistant polystyrene and is therefore suitable as a cover material for a hot beverage cup or the like.

The disposable cover according to the disclosed subject matter comprises a thermoformed sheet in the form of a lid for a hot beverage container. The sheet comprises a polymer composition consisting of a polyolefin and at least one mineral filler. The sheet has a thickness of less than about 0.035 inches and a heat distortion temperature comparable to at least impact polystyrene.

In an embodiment, the mineral filler may comprise any suitable mineral filler for increasing the heat distortion temperature of the polyolefin. For example, without limitation, the mineral filler can comprise a high aspect ratio filler, a low aspect ratio filler, or a blend of the two. For ease of understanding, the term "aspect ratio" of a particle is defined herein as the ratio of the largest dimension of the particle divided by the smallest dimension of the particle. The aspect ratio was determined by scanning under an electron microscope (magnification 2000 times) and visually examining the outer surface of the particles to determine the length and thickness of the particles.

A high aspect ratio filler is defined herein as a filler having an aspect ratio of at least about 5:1. The aspect ratio of the high aspect ratio filler of the subject matter disclosed herein is generally from about 5:1 to about 40:1, and preferably from about 10:1 to about 20:1. The high aspect ratio filler may comprise talc, mica, apatite or a combination thereof. Commercially available talc materials include, but are not limited to, JETFIL® 575 available from Luzenac America of Englewood, Colorado. Commercially available mica materials include SUZOREX® 325-PP available from Zemex Industrial Minerals, Inc. Commercially available aspartic stones include, but are not limited to, the ash stone of the NYGLOS® series available from NYCO Minerals Inc. of Calgary, Alberta, Canada.

The low aspect ratio filler of the disclosed subject matter typically has an aspect ratio of from 1:1 to about 3:1, preferably from 1:1 to about 2:1. The low aspect ratio filler may comprise calcium carbonate, barium sulfate or a combination thereof. Commercially available calcium carbonate includes, but is not limited to, OMYACARB FT® available from OMYA Inc. of Cincinnati, OH, or Supercoat® available from Imerys Performance Minerals Inc. of Alpharetta, Ga. An example of a commercially available barium sulfate is BARITE 2075® available from Polar Minerals in Mentor, Ohio.

When the at least one filler comprises a blend of a high aspect ratio filler and a low aspect ratio filler, the filler mixture can comprise any suitable weight percentage of the high aspect ratio filler and the low aspect ratio filler. For example, the filler mixture can include a high aspect ratio filler of at least 50 wt.%. In one embodiment, the filler mixture can have a high aspect ratio filler of from about 50 wt.% to about 80 wt.% and a low aspect ratio filler of from about 20 wt.% to about 50 wt.%.

According to one aspect, the polyolefin can be any suitable polyolefin. For example, without limitation, the polyolefin may be selected from the group consisting of polypropylene homopolymers, polypropylene impact copolymers, ethylene-propylene random copolymers, high density polyethylene, or combinations thereof. The polyolefin can be a blend of homopolymer polypropylene and impact copolymer polypropylene in any desired weight percentage (such as 60/40 blend) or blending rate sufficient to achieve the desired impact resistance properties of the composition.

According to one aspect, the polymer composition can consist essentially of a polyolefin and the at least one mineral filler. However, the polymer composition may further comprise any additives known to those skilled in the art. Additives can be packaged Such as, but not limited to, colorants, processing aids (such as processing aids typically used to treat compositions), or combinations thereof.

According to one aspect, the disposable cover can be made using a variety of conventional manufacturing and forming procedures, including thermoforming or injection forming procedures, but using a hot forming procedure herein. According to one manufacturing method, a small agglomerate of polyolefin resin is melted in a twin-screw extruder. The powder of the at least one mineral filler is mixed with the molten polyolefin and/or added to the molten polyolefin to form a blend. The blend is extruded through a die to form an extruded sheet. The extruded sheet is then thermoformed into the desired disposable lid shape. Alternatively, mineral filler compounds having a high filler content in the form of small agglomerates can be made by a typical compounding procedure and the small agglomerates can be further diluted to the desired filler content during the tablet extrusion process.

The thickness of the cover can be selected as desired, but is generally less than about 0.15 inches, preferably less than about 0.035 inches. Preferably, the cover can have a thickness of from about 0.01 inches to about 0.025 inches. The lid may have a natural color of the polyolefin/filler mixture, or a combination of colors or colors. As is well known in the art, the height, weight, shape and design of the lid can be selected to fit a suitable hot beverage container, such as a coffee cup. For example, the lid can weigh from about 3 grams to about 4 grams. Exemplary cover designs include, but are not limited to, U.S. Patent Nos. 7,819,271, 7,789,260, 7,691,302, D556,573, D544,793, D541,651, D541,650, D541, 153, D540,675, D540,674, D540,673, D540,672, D540,166, D540,165, D539,646, D533,778 , D635, 855, the first 7,731,047, 7,513,382, 7,246,715, D540,167, D539,650, D539,649, D536,249, D535,561, 7,159,732, 7,156,251, 7,134,566, 7,131,551, D530,602, 7,063,224, D514,445, D514,444, 6,874,649, 6,732,875, D489,260, D485,758, 6,679,397, 6,644,490, D478,006, D477,223, D476,891, D476,566, 4,753,365, D287,919, 4,615,459, and 4,589,569 The entire design of each of these patents is incorporated herein by reference.

According to one aspect of the disclosed subject matter, the heat distortion temperature ("HDT") (also known as the deformation temperature under load ("DTUL")) may be based on the deformation temperature of the edge position of the plastic under the bending load. The standard test method is determined by ASTM D648-06 (2006). For purposes of illustration and not limitation, Table 1 contains pure impact-resistant polystyrene, pure polypropylene ("PP"), pure high-density polyethylene ("HDPE") and according to ASTM D648-06 (2006). The heat distortion temperature measured by a plurality of mineral-filled polymer compositions according to the disclosed subject matter. The information provided in Table 1 is based on an injection molded rod having a nominal width of 12.7 mm, a thickness of 3.17 mm, and a span of 101.6 mm. A load of 2.5 N was applied to achieve a fiber stress of 0.455 MPa (66 PSI). The temperature of the heat transfer medium was ramped up at 2.0 ° C / min. The deformation was reset to zero at 30 ° C to allow for any low temperature creep. The temperature at which the sample is additionally deformed by 0.25 mm is considered to be the heat distortion temperature. In order to explain For purposes of clarity and not limitation, Figure 1 provides a graphical representation of the heat distortion temperature data provided in Table 1. Specifically, Figure 1 shows that the heat distortion temperature increases with the mineral filler content of four different combinations of polypropylene or high density polyethylene and talc or calcium carbonate as compared to pure HIPS as a control.

As can be seen in the data in Table 1 and Figure 1, the pure impact-resistant polystyrene (heat distortion temperature of 87 ° C) falls within the brewing temperature and supply temperature range of the coffee. At about 79 ° C to 80 ° C, the heat distortion temperature of the polypropylene copolymer or polypropylene homopolymer/copolymer blend is lower than the heat distortion temperature provided by the pure impact polystyrene. However, it has been shown that at about 69 ° C, the heat distortion temperature of pure high density polyethylene is not within the temperature range in which the cover made of pure high density polyethylene will perform satisfactorily.

Examples 1 to 20 of the subject matter disclosed in Table 1 show the heat distortion temperatures of various polyolefins in combination with mineral fillers at different mineral filler levels. In different combinations of polyolefin and mineral fillers, the calcium carbonate-filled polyolefin gradually increases in heat distortion temperature relative to the respective unfilled (i.e., pure) polyolefin as the mineral content increases. In contrast, when the mineral filler content is increased, the thermal change of the talc-filled polyolefin The increase in shape temperature is greater. Unexpectedly, the thermal deformation temperature of the talc-filled polypropylene has a more significant increase even if the talc content is as low as about 10%.

As shown in the data in Table 1 and Figure 1, the heat distortion temperature of the polymer composition according to the disclosed subject matter can be comparable, equal or greater than the heat distortion temperature of the impact resistant polystyrene. For example, to achieve a heat distortion temperature equal to or higher than the impact polystyrene, if the mineral filler has a high aspect ratio mineral (eg, talc), the polymer composition may include as little as about 10 weight percent. % mineral filler (Reference Example 12). In fact, as shown in Figure 1, when polypropylene is used, only talc powder of less than 10% by weight is required to achieve the same heat distortion temperature as impact polystyrene. In contrast, if the mineral filler comprises a low aspect ratio mineral filler (eg, calcium carbonate), the polymer composition can include at least about 20% by weight of the mineral filler (Reference Example 17), An equal or greater heat distortion temperature is achieved with respect to the impact resistant polystyrene.

As shown in Example 2, when the polyolefin comprises high density polyethylene, then the mineral filler comprises a high aspect ratio mineral filler (eg, talc) and the polymer composition comprises about at least 20% by weight of the For mineral fillers, the heat distortion temperature will be greater than the heat distortion temperature of the impact resistant polystyrene. As shown in Example 10, when the polyolefin comprises high density polyethylene, the mineral filler comprises a low aspect ratio mineral filler (eg, calcium carbonate) and the polymer composition comprises at least about 50% by weight of the mineral. For the filler, the heat distortion temperature will be greater than the heat distortion temperature of the impact resistant polystyrene. As shown in Example 12, when the polyolefin comprises polypropylene, the mineral filler comprises a high aspect More than a mineral filler (eg, talc), and the polymer composition includes at least about 10% by weight of the mineral filler, the heat distortion temperature will be greater than the heat distortion temperature of the impact polystyrene. As shown in Example 17, when the polyolefin comprises polypropylene, the mineral filler comprises a low aspect ratio mineral filler (eg, calcium carbonate) and the polymer composition comprises at least about 20% by weight of the mineral filler. The heat distortion temperature will be greater than the heat distortion temperature of the impact resistant polystyrene.

For purposes of illustration and not limitation, Table 1 and Figure 2 show the shrinkage characteristics of polypropylene, high density polyethylene, impact resistant polystyrene, and mineral filled polypropylene and mineral filled high density polyethylene. The shrinkage can be measured according to the ASTM D955 (1996) standard using an injection molded rod having a size of 12.7 mm x 3.2 mm x 127 mm according to the standard and also known in the art. Compared to impact-resistant polystyrene, mineral-filled polypropylene overcomes the disadvantages of polypropylene (pure) shrinkage mismatch, thus allowing the use of existing impact-resistant polystyrene processing to produce between about 0.5% and about A component with a similar shrinkage ratio between 1.0%. For example, as shown in Fig. 2, the talc-filled polypropylene having a talc content of 20% to 40% is suitable for replacing the impact-resistant polystyrene from the viewpoint of self-shrinkage. Similarly, mineral-filled high-density polyethylene can overcome the disadvantages of shrinkage mismatch of high-density polyethylene compared to polypropylene, thus allowing the use of existing polypropylene processing to produce approximately 1.25% similar to polypropylene. Up to about 1.75% mineral filled high density polyethylene parts. For example, as shown in Fig. 2, the talc-filled high-density polyethylene having a talc content of 30% to 50% from the viewpoint of self-shrinkage is suitable for replacing pure polypropylene.

According to another aspect, the carbon footprint of the polymer composition is lower than the carbon footprint of the impact resistant polystyrene. For example, the polymer composition has a lower greenhouse gas emissions than the greenhouse gas emissions of the impact resistant polystyrene. For purposes of illustration and not limitation, Table 2 shows greenhouse gas emissions over the life of the disclosed cover from manufacturing to disposal over a cover made of impact resistant polystyrene. As a hot beverage lid, both caps have similar stiffness and perform similar properties. The comparative example was made with an impact resistant polystyrene sheet of about 0.0214 inches thick and weighed about 3.83 grams. An example of the disclosed subject matter comprises 40% talc-filled polypropylene and is made from a 0.0167 inch thick piece and weighs about 3.32 grams. The basic unit consisting of 10,000 tablets is used to calculate greenhouse gas emissions. There are a number of factors that cause a significant reduction in greenhouse gas emissions based on examples of the disclosed subject matter. These factors include the polymer density, the GHG emissions of the matrix polymer and minerals, and the amount of mineral incorporated into the composition. As can be seen in Figure 2, the greenhouse gas emissions of talc-filled polypropylene caps are reduced by nearly 50% compared to caps made of impact-resistant polystyrene that perform similar properties.

While the present invention has been described in terms of a particular preferred embodiment, it will be appreciated by those skilled in the art that various modifications and improvements can be made without departing from the scope of the invention. For example, although the present application describes a disposable cover for a hot beverage container such as a coffee cup, the polymer composition according to the present application can be used to improve the heat of the mineral-filled polymer in addition to the closure. Other applications for deformation temperatures. Accordingly, this application is intended to cover such modifications and modifications In addition, although the various features of one embodiment of the present application are disclosed herein or are shown in the drawings of the embodiments and are not shown in other embodiments, it should be understood that the various features of an embodiment can be One or more features of another embodiment or a combination of features from a plurality of embodiments.

In addition to the specific embodiments set forth below, this application is also directed to embodiments having any other possible combinations of the features and the features disclosed above. Therefore, the specific features presented in the dependent technical solutions and the specific features disclosed above may be combined with each other within the scope of the present application, and it should be recognized that the present application is also specific to other embodiments having any other feasible combination. . Therefore, the description of the specific embodiments of the present application has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the application to the embodiments disclosed.

Figure 1 is a graph of the heat distortion temperature of pure impact-resistant polystyrene, neat polypropylene, pure high-density polyethylene, and certain mineral-filled polymer compositions, respectively, according to the disclosed subject matter.

Figure 2 is a pure impact-resistant polystyrene according to the disclosed subject matter. A graph of the shrinkage characteristics of olefins, neat polypropylene, pure high density polyethylene, and certain mineral filled polymer composites.

Claims (25)

A disposable cover comprising: a thermoformed sheet in the form of a lid for a hot beverage container, the sheet comprising a polymer composition comprised of a polyolefin and at least one mineral filler; wherein the sheet has a thickness less than It is about 0.035 inches and its heat distortion temperature is at least comparable to the heat distortion temperature of impact polystyrene. The disposable cover of claim 1, wherein the heat distortion temperature is at least about equal to a heat distortion temperature of the impact resistant polystyrene. A disposable cover according to claim 1, wherein the heat distortion temperature is at least about 87 ° C according to the standard test method ASTM D648-06 (2006) for the deformation temperature of the plastic at the edge position under a bending load. The disposable cover of claim 1, wherein the mineral filler comprises a high aspect ratio mineral filler. A disposable cover according to claim 4, wherein the mineral filler is selected from the group consisting of talc, mica, apatite or a combination thereof. The disposable cover of claim 4, wherein the polymer composition comprises at least about 10% by weight of a mineral filler. A disposable cover according to claim 1 wherein the mineral filler comprises a mineral filler having a low aspect ratio. The disposable cover of claim 7, wherein the mineral filler comprises calcium carbonate. The disposable cover of claim 7, wherein the polymer composition comprises at least about 20% by weight of a mineral filler. A disposable cover according to claim 1, wherein the polyolefin is selected from the group consisting of polypropylene homopolymerization A group of materials, polypropylene impact copolymers, ethylene-propylene random copolymers, high density polyethylene, or combinations thereof. A disposable cover according to claim 1 wherein the polyolefin comprises polypropylene, the mineral filler comprises a high aspect ratio mineral filler, and the polymer composition comprises at least about 10% by weight of the mineral filler. A disposable cover according to claim 1 wherein the polyolefin comprises polypropylene, the mineral filler comprises a mineral filler having a low aspect ratio, and the polymer composition comprises at least about 20% by weight of the mineral filler. The disposable cover of claim 1, wherein the polyolefin comprises high density polyethylene, the mineral filler comprises a high aspect ratio mineral filler, and the polymer composition comprises at least about 20% by weight of the mineral filler. . The disposable cover of claim 1, wherein the polyolefin comprises high density polyethylene, the mineral filler comprises a mineral filler having a low aspect ratio, and the polymer composition comprises at least about 40% by weight of the mineral filler. . The disposable cover of claim 1, wherein the polyolefin comprises polypropylene, the mineral filler comprises a high aspect ratio mineral filler, and the shrinkage of the polymer composition is comparable to the shrinkage of impact polystyrene. The disposable cover of claim 15 wherein the polymer composition has a shrinkage of from about 0.5% to about 1.0% as measured according to the ASTM D955 standard (1996). A disposable lid of claim 15 wherein the polymer composition comprises from about 20% to about 40% by weight of the mineral filler. A disposable cover according to claim 1, wherein the polyolefin comprises high density polyethylene, the mineral filler comprises a high aspect ratio mineral filler, and the shrinkage of the polymer composition is comparable to the shrinkage of polypropylene. The disposable cover of claim 18, wherein the polymer composition has a shrinkage of from about 1.25% to about 1.75% as measured according to the ASTM D955 standard (1996). The disposable cover of claim 18, wherein the polymer composition comprises from about 30% to about 50% by weight of the mineral filler. The disposable cover of claim 1, wherein the polymer composition consists essentially of a polyolefin and at least one mineral filler. The disposable cover of claim 1, wherein the polymer composition further comprises an additive selected from the group consisting of color formers, processing aids, and combinations thereof. A disposable lid of claim 1, wherein the hot beverage container is a coffee cup. The disposable cover of claim 1, wherein the carbon footprint of the polymer composition is lower than the carbon footprint of the impact resistant polystyrene. The disposable cover of claim 1, wherein the polymer composition has a greenhouse gas emission that is less than a greenhouse gas emission of the impact resistant polystyrene.