Patent Application
20140363105
The present disclosure relates to a bag, and in particular to a bag made of plastics materials. More particularly, the present disclosure relates to a bag with a closable mouth.
According the present disclosure, a bag includes a body and a floor appended to the body to define an interior region therebetween. The body is formed to include a mouth opening into to the interior region opposite the floor. The body and the floor are made from plastics materials.
In illustrative embodiments, the plastics materials are configured to provide means for supporting the body on ground underlying the body after the bag has been has been unfolded and arranged to be free standing so that the mouth opens into the storage space. The mouth remains open and the body remains extending upwardly away from ground without support from a user or a bag-support structure.
In illustrative embodiments, the plastics materials comprise high density polyethylene (HDPE) and low density polyethylene (LDPE). The HDPE comprises about 20% to about 40% of the weight of the material. The LDPE comprises about 20% to about 40% of the weight of the film.
Additional features of the present disclosure will become apparent to those skilled in the art upon consideration of illustrative embodiments exemplifying the best mode of carrying out the disclosure as presently perceived.
The detailed description particularly refers to the accompanying figures in which:
A first embodiment of a standup bag 10 in accordance with the present disclosure is shown, for example, in a folded arrangement in
Standup bag 10 is formed to include mouth 14 that opens into storage space 16 as shown, for example, in
Standup bag 10 is formed in bag-forming process 100 as shown in
The presently described technology is further illustrated by the following examples, which are set forth for purposes of illustration only and are not to be construed as limiting the invention or scope of the specific compositions described herein. Parts and percentages are by weight unless stated otherwise.
Disclosed herein are embodiments of a blended material or resin that provides rigidity to film structures, such as standup bags 10, 210. The blended resin is a blend of high density (HD) and low density (LD) polymeric materials. In one illustrative embodiment, a blended film comprises HD polyethylene (HDPE) and LD polyethylene (LDPE).
Rigidity is one property a material that in turn depends on two other properties of a material. As a result, rigidity is a function of sample thickness measured in gauge and sample stiffness. Stiffness is an inherent property of a material of which the film or sheet is made. The combined effect of these two factors is the rigidity that influences performance on converting machines. Rigidity of a polyolefin film can be measured by ASTM D2923-08. In one embodiment, a blended HDPE/LDPE film has a rigidity associated with an outside face, an inside face, and overall.
In one embodiment, a blended HDPE/LDPE film has a rigidity of at least about 325 mg*cm (milligram×centimeter). In another embodiment, a blended HDPE/LDPE film has a rigidity of about 325 mg*cm to about 450 mg*cm, about 345 mg*cm to about 450 mg*cm, about 350 mg*cm to about 450 mg*cm, about 355 mg*cm to about 450 mg*cm, about 360 mg*cm to about 450 mg*cm, about 370 mg*cm to about 450 mg*cm, about 375 mg*cm to about 450 mg*cm, about 325 mg*cm to about 445 mg*cm, about 325 mg*cm to about 440 mg*cm, about 325 mg*cm to about 430 mg*cm, about 325 mg*cm to about 425 mg*cm, about 325 mg*cm to about 420 mg*cm, about 325 mg*cm to about 415 mg*cm, about 325 mg*cm to about 410 mg*cm, or about 325 mg*cm to about 405 mg*cm. In another embodiment, a blended HDPE/LDPE film has a rigidity (outside face, inside face, or overall) of at least about 325 mg*cm, about 330 mg*cm, about 335 mg*cm, about 345 mg*cm, about 350 mg*cm, about 355 mg*cm, about 360 mg*cm, about 365 mg*cm, about 370 mg*cm, about 375 mg*cm, about 380 mg*cm, about 390 mg*cm, about 395 mg*cm, about 400 mg*cm, about 405 mg*cm, about 410 mg*cm, about 415 mg*cm, about 420 mg*cm, about 425 mg*cm, about 430 mg*cm, about 435 mg*cm, about 440 mg*cm, about 445 mg*cm, or about 450 mg*cm.
In an embodiment, a blended HDPE/LDPE film is used in the production of standup bags 10, 210. A standup bag in accordance with the present disclosure has a square or rectangular shape, but may have any other suitable shape like circular.
LDPE. As used herein, low density polyethylene (LDPE) is defined as a polyethylene polymer with a density in the range of about 0.91 g/cm3 to about 0.93 g/cm3. LDPE may be polymerized through a free radical polymerization and has a high degree of short and long chain branching. The term LDPE is intended to include high pressure low density polyethylene (HPLDPE) polymerized through a high pressure free radical polymerization. For example, LDPE may be an ethylene homopolymer made using a free radical initiator at pressures from about 15,000 psi to about 50,000 psi and at temperature up to about 300° C. in a tubular or stirred reactor. According to this polymerization technique, numerous long chain branches may be formed along the length of the polymer. In one aspect, the LDPE may be characterized as having a single low melting point. For example, a 0.92 g/cm3 density LDPE would typically have a melting point at about 112° C. In another aspect, LDPE may not pack into the crystal structures well. Therefore, LDPE may have a tendency to form amorphous solid structures. Accordingly, the intermolecular forces are weaker and the instantaneous-dipole induced-dipole attraction may be lower. Furthermore, LDPE has a lower tensile strength than HDPE but comparably greater ductility.
In illustrative embodiments, the film comprises LDPE having a Melt Index (MI) of about 0.1 g/10 min to about 20 g/10 min. In one embodiment, the film comprises LDPE having a MI of about 2 g/10 min. In another embodiment, the film comprises LDPE having a MI of about 0.2 g/10 min. In illustrative embodiments, the film comprises LDPE having a density of about 0.91 g/cm3 to about 0.93 g/cm3. In another embodiment, the film comprises LDPE having a density of about 0.92 g/cm3.
HDPE. In illustrative embodiments, the multilayer film includes at a layer comprised of high density polyethylene, referred to herein as HDPE. In another embodiment, the high density polyethylene is a product of reacting ethylene by a means to form a product exhibiting very little short chain or long chain branching so that the polyethylene has a highly crystalline structure.
In illustrative embodiments, the high density polyethylene is a homo-polymeric high density polyethylene with a mono-modal Molecular Weight Distribution (MWD). The homo-polymeric high density polyethylene is a product of reacting ethylene such that the product has substantially no branching. In one embodiment, the homo-polymeric high density polyethylene has a MI of about 1 g/10 min to 9 g/10 min and a density of about 0.935 g/cm3 to about 0.96 g/cm3.
LLDPE. As used herein, linear low-density polyethylene (LLDPE) is used to describe a copolymer of ethylene and an alpha olefin comonomer made through a single site catalyzed reaction (e.g., through a metallocene catalyzed reaction (mLLDPE)), or Ziegler Natta catalysts. Included within the scope of the present disclosure are physical blends of LLDPE with an elastomer or high pressure low density polyethylene. LLDPE, as used herein, includes polymers made through non-metallocene or post-metallocene catalyzed reactions resulting in a copolymer of ethylene and an alpha olefin copolymer. LLDPE includes copolymers made with various alpha olefin monomers including 1-butene, 3-methyl-1-butene, 1-propylene, 3-methyl-1-pentene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-hexene, 1-octene or 1-decene. The alpha olefin comonomer may be incorporated from about 1% to about 20% by weight of the total weight of the polymer. In other embodiments the alpha olefin comonomer may be incorporated from about 1% to about 10% by weight of the total weight of the polymer. LLDPE also includes copolymers incorporating long-chain branching (e.g. chains containing as many as 300 carbons). LLDPE also includes C6 and C8 LLDPE.
Linear low density polyethylene polymers (LLDPE) have a density of about 0.900 g/cc to about 0.945 g/cc. Preferably, LLDPE has a density that is less than about 0.930 g/cc. LLDPE has rapidly increasing commercial importance in commodity and industrial applications including blown and cast films, injection molding, rotational molding, blow molding, pipe, tubing, and wire and cable manufacturing. Intensive research has been directed to development of high performance LLDPE resins having improved impact strength, higher toughness, higher transparency, less low molecular weight component content, and narrower compositional distributions.
Advanced Ziegler-Natta catalysts based on supported titanium systems can produce high performance LLDPE resins, such as Super-Hexene resins. Super-Hexene resins are ethylene/hexene copolymers having narrow molecular weight distributions, uniform compositional distribution, and high performance properties comparable to ethylene-octene copolymers produced by single site catalysts. The advanced Ziegler-Natta catalysts are directly applicable to existing fluidized gas phase processes, without polymerization process modification.
Examples of commercially available ethylene-hexene-1 LLDPEs which may be used are GA 615-050 (density 0.918 g/cm3; 7 MI; Equistar Chemicals L. P.); PE 7235 (density 0.924 g/cm3; 3.5 MI; Chevron Phillips Chemical Co.); NTX 095 (ExxonMobil Chemical Co.), and LL 3003 (density 0.918 g/cm3; 3.2 MI; ExxonMobil Chemical Co.).
cPE. As used herein, the term catalyzed polyethylene (cPE) is used generally to describe a copolymer of ethylene and an alpha olefin comonomer made through a catalyzed reaction (e.g., through a Ziegler-Natta, Philips, metallocene, or other single site catalyzed reactions). cPE includes polymers made through non-metallocene or post-metallocene catalyzed reactions resulting in a copolymer of ethylene and an alpha olefin copolymer. cPE includes copolymers made with various alpha olefin monomers including 1-butene, 3-methyl-1-butene, 3-methyl-l-pentene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-hexene, 1-octene or 1-decene. In one embodiment, the cPE is a copolymer of ethylene and one selected from the group of 1-hexene and 1-octene. In another embodiment, the cPE is a copolymer of ethylene and 1-octene.
In illustrative embodiments, cPE has a MWD within the range of about 1 to about 6. In one embodiment, cPE has a MWD within the range of about 1.5 to about 5. In another embodiment, cPE has a MWD within the range of about 2 to about 4. In illustrative embodiments, the cPE has an average molecular weight from about 20,000 g/mol to about 500,000 g/mol, preferably from about 50,000 g/mol to about 200,000 g/mol.
VLDPE. As used herein, VLDPE is a cPE having a density of about 0.88 g/cm3 to about 0.92 g/cm3 or from about 0.89 g/cm3 to about 0.91 g/cm3. It may be referred to as ultra-low density polyethylene (ULDPE) or very low density polyethylene (VLDPE). VLDPE may have a MI of from about 0.5 g/10 min to about 5 g/10 min, preferably from about 1 g/10 min to about 4 g/10 min. For example, a VLDPE may have a density of about 0.91 g/cm3 and a MI of about 3 g/10 min. A VLDPE may have a density of about 0.90 g/cm3 and a MI of about 4 g/10 min. A VLDPE having a density from about 0.90 g/cm3 to about 0.91 g/cm3 and a MI of about 1 g/10 min may also be used. In one aspect, the characteristic density may have been achieved by copolymerizing ethylene with one of 1-butene, 1-hexene, 4-methyl-1-pentene, or 1-octene. In one embodiment, the VLDPE is a copolymer of ethylene and one comonomer selected from the group of 1-hexene and 1-octene. In another embodiment, the cPE is a VLDPE being a copolymer of ethylene and 1-octene, wherein copolymer has a mean comonomer percentage of about 10%.
In one embodiment, a blended film comprises HD polyethylene (HDPE) and LD polyethylene (LDPE). In another embodiment, a blended film comprises a combined LDPE and HDPE of about 50% to about 80% of the weight of the film. In an embodiment, a blended film comprises a combined LDPE and HDPE of about 50% to about 75% of the weight of the film. In an embodiment, a blended film comprises about 50% to about 60% of a combined LDPE and HDPE. In an embodiment, a blended film comprises about 55% to about 75% of a combined LDPE and HDPE. In an embodiment, a blended film comprises about 55% to about 60% of a combined LDPE and HDPE. In an embodiment, a blended film comprises about 50%, 55%, 56%, 57%, 58%, 59%, 60%, 65%, 70%, 75%, or 80% of a combined LDPE and HDPE.
In another embodiment, a blended film comprises HDPE and LDPE, wherein the blended film comprises about 20% to about 40% HDPE, about 25% to about 40% HDPE, about 30% to about 40% HDPE, about 35% to about 40% HDPE, about 25% to about 35% HDPE, about 25% to about 35% HDPE, about 25% to about 30% HDPE, or about 30% to about 35% HDPE. In an embodiment, a blended film comprises HDPE and LDPE, wherein the blended film comprises about 20%, about 21%, about 22%, about 23%, about 24%, about 25%, about 26%, about 27%, about 28%, about 29%, about 30%, about 31%, about 32%, about 33%, about 34%, about 35%, or about 40% HDPE.
In an embodiment, a blended film comprises HDPE and LDPE, wherein the blended film comprises about 20% to about 40% LDPE, about 25% to about 40% LDPE, about 30% to about 40% LDPE, about 35% to about 40% LDPE, about 25% to about 35% LDPE, about 25% to about 35% LDPE, about 25% to about 30% LDPE, or about 30% to about 35% LDPE. In an embodiment, a blended film comprises HDPE and LDPE, wherein the blended film comprises about 20%, about 21%, about 22%, about 23%, about 24%, about 25%, about 26%, about 27%, about 28%, about 29%, about 30%, about 31%, about 32%, about 33%, about 34%, about 35%, or about 40% LDPE.
In an embodiment, other materials 108 used to make a film may include include an LLDPE. In an embodiment, a LLDPE can be super hexene. In particular, the LLDPE, including super hexene, can be about 10% to about 40%, about 10% to about 30%, about 10% to about 20%, about 10% to about 15%, about 10% to about 12%, about 12% to about 15%, about 12% to about 20%, about 12% to about 30%, about 12% to about 40%, about 15% to about 30%, and about 15% to about 40%. In an embodiment, the LLDPE, including super hexene, can be about 10%, about 12%, about 15%, about 20%, about 30%, and about 40%.
In an embodiment, other materials 108 used to make a film may include calcium carbonate. In an embodiment, calcium carbonate is about 5% to about 15% of the weight of a film. In an embodiment, calcium carbonate comprises about 5%, about 8%, about 9%, about 10%, about 12%, or about 15% of the weight of a film.
In an embodiment, other materials 108 used to make a film may include a slip agent. In an embodiment, a slip agent is about 0.5% to about 2% of the weight of a film. In an embodiment, a slip agent comprises about 0.5%, about 0.75%, about 0.8%, about 0.9%, about 1.0%, about 1.1%, about 1.2% about 1.25%, about 1.5%, or about 2.0% of the weight of a film. As used herein, a slip agent is an additive used to reduce a polyolefin film's resistance to sliding. In an embodiment a slip agent can be a long chain fatty acid amide. In an embodiment, the slip agent can be an unsaturated fatty acid amide. In an embodiment, the slip agent can be a C-18, C-20, or C-22 fatty acid amide. Slip agents include, but are not limited to, about 1%, 2%, 3%, 4%, 5%, 5.5%, or 6% erucamide in LDPE, LLD, or PP. Slip agents can also include, but are not limited to, about 3% to about 12%, about 5% to about 10%, about 5%, or about 10% oleamide in LDPE, PE, or LLD.
In an embodiment, other materials 108 used to make a film may include a nucleating agent. In an embodiment, a slip agent is about 0.5% to about 4% of the weight of a film. In an embodiment, a slip agent comprises about 0.5%, about 1.0%, about 1.5%, about 2.0%, about 2.5%, about 3.0%, about 3.5%, or about 4.0% of the weight of a film.
In an embodiment, other materials 108 used to make a film may include a coloring agent. In an embodiment, a coloring agent is about 0.5% to about 4% of the weight of a film. In an embodiment, a coloring agent comprises about 0.5%, about 1.0%, about 1.5%, about 2.0%, about 2.5%, about 3.0%, about 3.5%, or about 4.0% of the weight of a film. The coloring agent may give the standup bag a black color, orange color, brown color, blue color, or white color. The coloring agent may be omitted providing a transparent, opaque, or clear bag.
ASTM standard test methods incorporated by reference. Reference is made to each ASTM standard test methods described herein, which ASTM standard test methods are hereby incorporated by reference herein, for disclosure relating to the methods for testing polymeric compositions and films made thereof.
Standup bag 10, in accordance with the present disclosure, includes a closure system 18, a body 20, and a floor 22 as shown in
Body 20 includes a first wall 31, a first gusset 33, a second wall 32, and a second gusset 34 as shown in
Floor 22 of standup bag 10 is formed as a result of additional heat sealing which causes floor 22 to have a generally square or rectangular shape when viewed from the bottom. First gusset 33 is further coupled to first side wall 31 along a first seal line 25 which extends away from bottom seal line 28 at an angle 35 of about 35.5 degrees as measured between first seal line 25 and bottom seal line 28. First gusset 33 is also coupled to second side wall 32 along a second seal line 26 which extends away from bottom seal line 28 at the angle 35 of about 35.5 degrees as measured between second seal line 26 and bottom seal line 28 as shown in
Closure system 18 is coupled to the top portion of body 20 opposite floor 22 and includes four flaps 18A, 18B, 18C, 18D as shown in
Another embodiment of standup bag 210 is shown, for example, in
Body 220 includes a first wall 231, a second wall 232, a first end wall 233, a second end wall 234, a third end wall 235, and a fourth end wall 236 as shown in
Closure system 218 is appended to the top portion of body 220 opposite floor 222 and a strip 218A of material which extends mouth 214 as shown in
Rigid film formulations were prepared using conventional extrusion processes. The formulations of the films are shown in Table 1.
57a
75a
aMixture of re-pelletized regrind of LDPE and HDPE (repro HDPE-LDPE)
Rigid film formulations C and D from Table 1 were used to produce standup bags 10, 210. The standup bags from film formulations C and D, along with a commercially available bag, were characterized and tested for various properties shown in Table 2.
aStandard Guide for Determination of Thickness of Plastic Film Test Specimens (ASTM
bStandard Test Method for Tear Resistance (Graves Tear) of Plastic Film and Sheeting
cStandard Test Methods for Impact Resistance of Film by Free Falling Dart Method
dStandard Test Method for Transparency of Plastic Sheeting (ASTM D1746-09)
eStandard Test Properties for Tensile Properties of Plastics (ASTM D638-08)
f Standard Test Method for Stiffness of Fabrics (flexural rigidity test by cantilever
A rigid film formulation is used to produce a standard contractor bag with a square bottom. A bag is produced using in-line extrusion and the formulation as described in Tables 1 and 2 as formulation “C”. A gusset (9 inches) to produce the square bottom feature is inserted in the tower via a gusset board on one side of the bubble.
As the lay flat film reaches the bottom of the tower, it enters into a 50 inch Hudson Sharp shuttle bag machine. The machine uses two sealing heads (front and back) with heated bottom plenums for increasing the seal quality. This produces the bag's side seal from the top to the bottom of the bag, including the gusset area at the bottom of the bag. A perforation blade is between the front and the back sealing head allowing the separation of each bag.
After the sealing and perforation in the shuttle bag machine, the film is folded twice on a stand-alone folder. The folded, individual perforated bags are then winded on a spinner winder at a pre-set count.
A rigid film formulation is used to produce a standard contractor bag with a square bottom. A bag is produced using in-line extrusion and the formulation as described in Tables 1 and 2 as formulation “C”. A gusset (8.5 inches) to produce the square bottom feature is inserted in the tower via a gusset board on both sides of the bubble.
As the lay flat film reaches the bottom of the tower, it enters into a 50 inch Hudson Sharp shuttle bag machine. The machine uses one sealing head with a heated bottom plenum for increasing the seal quality. This produces the bag's bottom seal from the left to the right at the bottom of the bag, including the gusset area on the left and right side of the bag. A perforation blade is located next to the sealing head allowing the separation of each bag.
An angle seal is used to seal both gussets at the bottom of the bag next to the seal. These seals are at a 45 degree angle from the bottom seal. The angle seal touches the bottom seal starting at the center of the bag or the start of the side gussets and is at a 45 degree angle away from the bottom seal to the outer edge of the bag on both sides (left and right of the bag). The angle seal gives the bottom of the bag when opened a square bottom.
After the sealing and perforation in the shuttle bag machine, the film is folded twice on a stand-alone folder. The folded, individual perforated bags are then winded on a spinner winder at a pre-set count.
The blended HDPE/LDPE resin formulation C (see Tables 1 and 2) was tested for rigidity/stiffness using ASTM D1388-08. This ASTM method was reapproved in 2012. In particular, the resin was tested using the cantilever test, which employs cantilever bending of the resin under its own mass.
In the cantilever test, a specimen from the blended HDPE/LDPE resin formulation C was slid at a specified rate in a direction parallel to its long dimension, until its leading edge projected from the edge of the horizontal surface. The length of the overhang was measured when the tip of the specimen was depressed under its own mass to the point where the line joined the top to the edge of the platform made a 41.5° angle with the horizontal. From this measured length, the bending length and flexural rigidity were calculated.
