US20250040742A1

US20250040742A1 - Biodegradable hospital curtain and curtain system, method of making and composition

Info

Publication number: US20250040742A1
Application number: US18/393,128
Authority: US
Inventors: Arlen Olsen; Richard Mayer
Original assignee: Bannack Medical LLC
Current assignee: Bannack Medical LLC
Priority date: 2023-07-24
Filing date: 2023-12-21
Publication date: 2025-02-06

Abstract

Disclosed is a biodegradable hospital privacy curtain and curtain hardware having: a non-biodegradable polymer selected from a group consisting of polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC) and combinations thereof; and an additive comprising a blend or copolymer of (1) a first polymer selected from a poly-lactic acid (PLA), a polyhydroxyalkanoates (PHA) or a combination thereof and (2) a second polymer which is a poly-terephthalate. The curtain has a first hardness on the durometer scale and the curtain hardware has a second hardness on the durometer scale, different than the first hardness on the durometer scale. Also disclosed is a method of making a hospital disposable.

Description

RELATED REFERENCES

This application claims priority to U.S. provisional patent application Ser. No. 63/528,602 filed Jul. 24, 2023 and U.S. provisional patent application Ser. No. 63/531,639 filed on Aug. 9, 2023, both of which the entirety of is hereby incorporated by reference.

FIELD OF THE INVENTION

Disclosed is a biodegradable hospital disposable. In particular, is a biodegradable disposable privacy curtain and curtain system having a lockable quick-release system, most often, for use in health care facilities to maintain a clean environment, a method and composition.

BACKGROUND

Disposal of plastic waste is a serious environmental problem. Increased use of plastics has resulted in a growing environmental impact. To combat this, bioplastics such as biodegradable polymers are being developed to be used as an alternative for non-biodegradable polymer materials. The best option for managing non-biodegradable plastic waste is to replace non-biodegradable materials with biodegradable polymers as they are environmentally friendly. Alternatively, non-biodegradable plastics may be recycled. Many of the products that hospitals use are disposable plastic products that are non-biodegradable. This is a problem and a growing concern for hospitals and healthcare facilities meeting sustainability goals.
Recently, hospitals are moving away from traditional cloth curtains due to their retention of infectious disease due to their porosity. Instead, they are moving toward a hospital disposable, such as a nonwoven disposable polypropylene curtain. With increased demand for disposable curtains, this creates a problem for being able to dispose of the curtains after use. Many solutions are being considered other than placing them in landfills, such as recycling by melting the curtains down. This creates the challenge of having the hospitals obtaining adequate recycling solutions. Many hospitals are also under pressure to come up with sustainability solutions for hospital waste.

SUMMARY

An aspect is to make a biodegradable privacy curtain or one that will degrade in a landfill much quicker than a conventional polypropylene curtain.
Another aspect is to have an additive material that can make most polymeric compositions biodegradable by merely mixing it in with the polymeric material any time before the polymeric material is formed into an article.
Another aspect is to provide a method for preparing a biodegradable privacy curtain.
A further aspect is to provide a composition of biodegradable privacy curtain.
A further aspect is to provide a composition of biodegradable hardware such as curtain hangers.
One embodiment of the present invention relates to a biodegradable hospital privacy curtain comprising: a curtain comprised of: a non-biodegradable polymer selected from a group consisting of polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC) and combinations thereof; and an additive comprising a blend or copolymer of (1) a first polymer selected from a poly-lactic acid (PLA), a polyhydroxyalkanoates (PHA) or a combination thereof and (2) a second polymer which is a poly-terephthalate.
In another embodiment of the present invention relates to biodegradable hospital privacy curtain hardware comprising: curtain hardware comprised of: a non-biodegradable polymer selected from a group consisting of polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC) and combinations thereof; and an additive comprising a blend or copolymer of (1) a first polymer selected from a poly-lactic acid (PLA), a polyhydroxyalkanoates (PHA) or a combination thereof and (2) a second polymer which is a poly-terephthalate.
In another embodiment of the present invention relates to a biodegradable hospital privacy curtain and curtain system comprising: a curtain; and curtain hardware, wherein the curtain and curtain hardware are both made from a material comprised of: a non-biodegradable polymer selected from a group consisting of polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC) and combinations thereof; and a biodegradable additive, wherein the curtain has a first hardness on the durometer scale and the curtain hardware has a second hardness on the durometer scale, different than the first hardness on the durometer scale.
Another embodiment of the present invention includes a biodegradable hospital privacy curtain and curtain system comprising: a curtain; and curtain hardware, wherein the curtain and curtain hardware comprise a non-biodegradable polymer selected from a group consisting of polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC) and combinations thereof; and an additive comprising a blend or copolymer of (1) a first polymer selected from a poly-lactic acid (PLA), a polyhydroxyalkanoates (PHA) or a combination thereof and (2) a second polymer which is a poly-terephthalate.
The further embodiment of the present invention provides a method of making a hospital disposable, the method comprising: adding 1 wt. % of an additive consisting of 51% poly-L-lactic acid (PLLA) polymer and 49% poly(butylene adipate-co-terephthalate) (PBAT) to a mass of solid polypropylene beads, thereby producing an admixture of the solid polypropylene beads and the additive; mixing the admixture until a homogenous mixture is produced; and forming the homogenous mixture into a hospital disposable.
The further embodiment of the present invention provides composition of matter comprising: a non-biodegradable polymer selected from a group consisting of polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC) and combinations thereof; an additive comprising a blend or copolymer of (1) a first polymer selected from a poly-lactic acid (PLA), a polyhydroxyalkanoates (PHA) or a combination thereof and a second polymer which is a poly-terephthalate; and wherein the non-biodegradable polymer is present in a concentration from 90-99.9 wt. %, the additive is present in a concentration from 0.1-10 wt. % and the additive has 30-70 wt. % of the first polymer and 30-70% of the second polymer.
A further embodiment of the present invention is a composition of matter comprising: a polypropylene (PP); an additive consisting of a blend or copolymer of (1) a poly-lactic acid (PLA) and (2) a poly-terephthalate; and wherein the polypropylene is present in a concentration from 95-99.9 wt. %, the additive is present in a concentration from 0.1-5 wt. % and the additive has 45-55 wt. % of the poly-lactic acid (PLA) and 45-55% of the poly-terephthalate.

BRIEF DESCRIPTION

Some of the embodiments will be described in detail, with reference to the following figures, wherein like designations denote like members, wherein:

FIG. 1 shows a curtain system according to an embodiment of the invention;

FIG. 2 shows a front view of a curtain system according to an embodiment of the invention;

FIG. 3 shows a side view of a curtain system according to an embodiment of the invention;

FIG. 4 shows an alternate embodiment of a curtain system of the invention.

FIG. 5 shows a first perspective view of a quick release system according to an embodiment of the invention;

FIG. 6 shows a second perspective view of a quick release system according to an embodiment of the invention;

FIG. 7 shows a first side of the inside of a quick release system according to an embodiment of the invention;

FIG. 8 shows a second side of the inside of a quick release system according to an embodiment of the invention;

FIG. 9 shows a perspective view of a sliding lock used in a locking mechanism according to an embodiment of the invention;

FIG. 10 shows another perspective view of a sliding lock used in a locking mechanism according to an embodiment of the invention;

FIG. 11 shows a perspective view of a curtain holder;

FIG. 12 shows another perspective view of a curtain holder;

FIG. 13 shows a component of a curtain holder; and

FIG. 14 shows another component of a curtain holder;

DETAILED DESCRIPTION

Referring to FIG. 1 is a disposable curtain system 100. The disposable curtain system 100 is attached to the ceiling by a track 110. The track may be attached directly to the ceiling or hang from the ceiling on extensions. Running through the track 110 are roller hooks 120. The roller hooks 120 have a hook 125 on the end thereof for attaching an extension or elongate member 140. So that the extension does not come off the hook 125, a cover 130 for the hook 125 is provided.
The extension 140 may be telescoping poles, poles that may be discreet sizes and interchanged depending on size needed. Since the extension will remain in place it is important that is easily cleanable for infectious diseases with an extension pole that has disinfectant. The material of the extension should not absorb liquids but should be made from a nonabsorbent plastic such as polyvinyl, acrylic, polyacrylic, nylon, carbon composite, PVC, polyethylene or the like. It may also be made from a biodegradable material as hereinafter described.
The curtain 180 comes in discreet sections, such as 6-12 feet and most commonly 9 feet. The curtain discreet sections of 9-12 feet may be snapped together with snaps 105 so as to make longer curtains. The curtains are made from disposable or recyclable, biodegradable material as hereinafter described. The curtains 180 may be attached to the extension 140 with a quick-release mechanism or quick-release curtain attachment 149 having a body 150 and a curtain attachment assembly or curtain attachment or curtain holder 160. The quick-release mechanism has a locking mechanism 80. The curtain holder 160 during shipping and the initial assembly may be held together with a zip-tie, twist tie 90 or a retainer such as 500 shown in FIG. 4 . Optionally, a second curtain or mesh 181 may be used with the extension and attached to the hood attachment or by other means.
Referring to FIG. 2 , a track 110 is shown. The track is bolted, screwed, glued or otherwise attached to the ceiling. The track may also be on a hanging system and hang from the ceiling. The track 110 has an end piece (not shown) with snap connectors for the end piece. Running inside the track are roller hooks 120 having rollers. Additionally, other types of arrangements other than rollers 120 may be used so long as the slide easily along the track guides 118. Extending from the rollers are an eyelet 123 to which the eyelet of the hook 124 is attached. Other arrangements may be envisioned such as chains and other extenders for the roller hook. Over each hook, a covering 130 is affixed for quickly attaching the attachment 130 to the hook 125. FIG. 2 shows a housing or body 150, locking mechanism 80 and curtain holder 160 all for attaching the disposable curtains 180.
Referring to FIG. 3 is the quick-release curtain mechanism 149 having a body or housing 150 and a locking mechanism 80. The curtain attachment or curtain holders 160 has an alignment member 161 for alignment with other curtain holders 160. An advantage of the curtain holders 160 is that they can align and be held together using the alignment members 161 which insert in a receiving member (not shown see 167 in FIG. 11 ). In this manner all the curtain holders 160 may be simultaneously inserted into the channels 151 as shown in FIGS. 7 and 8 . The curtain holders, extension holder and hook attachment are all made with injection molded parts using biodegradable materials as hereinafter described. It should be noted that although the curtain and its hardware are made using different manufacturing processes (i.e., a non-woven web extrusion of the curtain versus injection molding of the curtain hardware), they are both made from the same material.
FIGS. 5-8 show the quick release curtain mechanism or quick release curtain attachment 149 and locking mechanism 80 having a body 150 for holding the head 163 of the curtain attachment. Referring to FIG. 5 , the quick release body or housing 150 has an upper side 300 and a lower side 302. The lower side has a slot 311 for receiving the neck (See 162 in FIGS. 11 and 12 ) of the curtain holder 160. Openings 321 are shown which allow flexibility of the arms 322 (see FIG. 5 ). A cavity 325 is shown which matches protrusion 320 so that the quick release and locking mechanisms may match when in an array as shown in FIGS. 1 and 2 . The locking mechanism 80 (see FIGS. 9 and 10 ) slides in a first sliding slot 380. Nibs 381 and 382 engage the catch 381. The handle 810 of the locking mechanism 80 assists in sliding the lock up and down. On the side of the handle 810 is a female opening 820 for receiving a male protrusion 821.
FIG. 6 shows the opposite side of the quick release locking mechanism shown in FIG. 5 . On this side can be seen the male protrusions 821 on the handle 810 of the locking mechanism 80. Also, can be seen the protrusions 320. Arms 322 may be seen inside cavities which lock the two pieces together. The quick release locking mechanism 80 may be made injection molding, machining or other manufacturing technics.
FIG. 7 shows a first side and an inside of a first side of the quick release curtain mechanism 149 and locking mechanism 80. Shown are the nibs 381 and 382 in the first sliding slot 380 for receiving the catch 831. The catch 831 slides along the first sliding slot 380. A second sliding slot 385 is also shown for receiving the forks 837, 836 of the locking mechanism 80. When the head 163 is in place at the base of the opening 310, the forks 837 and 836 may be slid into place. As the forks 837, 836 slide toward the neck receiving slot 311, the head 163 is locked into place. As the forks 837, 836 are moved away from the neck receiving slot 311 the head 163 may be removed. 151 shows the channel for receiving neck receiving opening 311, the head 163 can be removed. The channel opening or channel 151 is located on the side, front or back of the housing 150 so that when the head 163 is inserted it may be held in place by gravity. Cavity 319 a is in place for receiving a magnet (not shown). The magnet assists in holding the array of quick release curtain mechanism 149 and locking mechanisms 80 in place as shown in FIGS. 1 and 2 . 321 shows an opening for locking arms 322 to hold a first side of the quick release body or housing 150 to a second side of the quick release body or housing 150. Alignment posts 304 assist in aligning the first side and second side of the body or housing 150 together. 341 shows a channel for receiving a cable 133. Cavity 340 holds a swagged end of the cable in place.
FIG. 8 shows the second side of the body 150 of the quick release curtain mechanism 149 and locking mechanism 80. Shown are receiving openings 309 for receiving the alignment posts 304 for alignment of both sides of the body 150. The arms 322 for locking the two sides together are flexible so that the pieces may be snapped into place. This is so that the pieces may readily be assembled and disassembled for insertion and removal of the cable in channel 341 and swaged piece in 340. The arms 322 have a head with a catch 323. The arms 322 have a narrow section 324 for flexibility.
FIGS. 9 and 10 show the locking mechanism 80. The locking mechanism 80 has a forked base 835 with tines 836 and 837. The tines 836 and 837 having a curved end and are spaced apart. The base 835 and tines 836, 837 slide through the second sliding slot 385. The tines are spaced apart a distance 383 from each other. The spacing 838 is so that the neck 162 can have a greater degree of movement when installed. In the first sliding slot, the catch 831 may slide through. The catch 831 is slotted at 833 and has a top and bottom part 832 so that it may flex when engaging the nibs 382 and 381. Alternatively, the catch may be solid for a firmer grip. The base 835 has a holder 830 for the handle 810 of the locking mechanism 80. The handle 810 has a lower face 808 and an upper face 809 so that it may be gripped by fingers. The base 835 has a lower face 839.
The curtain 180 and second curtain or mesh 181 are a non-woven web which is manufactured mixing polymeric beads and additive beads as hereinafter described together and then binding and melting them by increasing temperature to form a sheet or web (similar to paper on a paper machine).
With reference to FIGS. 11 through 14 , a curtain holders 160 is shown. The curtain holder has a first piece 170 and a second piece 165. The first piece 170 has a head 163 with a flat part 168 and a neck 162. The flat part 168 of the head 163 is for guiding the head into the channel 151 in order to allow adequate clearance. The first piece 170 and second piece may be attached together with arms 166 and locking head 159. The locking head 159 goes into opening 158 to snap into place. Other forms of attachment may also be used such as adhesive, melting of plastic, etc. The curtain holders 160 also include a guiding slot 167 and a protrusion 161 for alignment when the curtains an in an array. Projections 91 and 92 are to assist in aligning a twist wire (see FIG. 1 ) or an alignment tool or retainer 500 in FIG. 4 .
In addition to the above embodiments, it is envisioned that other types of sliding locking mechanism 80 may be made. Sliding not only includes linear sliding, but also rotary sliding of parts.
The non-woven polypropylene curtains are typically made using a process called “spunbonding.” Spunbonding is a method of producing non-woven fabrics from polypropylene fibers. The process involves extruding molten polypropylene, which then solidifies into fine fibers. These fibers are collected and bonded together to form a cohesive sheet of non-woven fabric, which is then used to make curtains and other products. Here are the main steps involved in manufacturing non-woven polypropylene curtains:
Polymer Extrusion: The process starts with the extrusion of polypropylene polymer. Polypropylene resin is melted and then forced through fine spinnerets (nozzles with small holes) to create continuous filaments or fibers.
Filament Laying: The extruded filaments are laid down onto a moving conveyor belt in a random or semi-random arrangement. This web of filaments forms the primary layer of the non-woven fabric.
Web Formation: As the filaments are laid down, the random arrangement creates a loose web of fibers. The thickness and weight of the web can be controlled based on the speed of the conveyor belt and the amount of extruded polymer.
Bonding: The loose web of filaments needs to be bonded together to create a cohesive non-woven fabric. This can be achieved through one of several methods:

- a. Heat Bonding: The web of filaments passes through a heated oven or calender rolls, where the heat softens the polypropylene fibers and causes them to bond together as they cool down.
- b. Chemical Bonding: Chemical binders or adhesives can be applied to the web to bond the fibers together.
- c. Mechanical Bonding: The web can be mechanically needled or entangled to interlock the fibers and form a strong fabric.

Finishing: After bonding, the non-woven fabric may undergo additional finishing processes to improve its properties, such as adding water or oil repellency, antimicrobial, flame resistance, or dyeing to achieve the desired color.
Conversion: Once the non-woven fabric is ready, it is cut and sewn into the shape of curtains. Grommets, hems, and other finishing touches may be added as required.
Non-woven polypropylene curtains have gained popularity due to their affordability, lightweight, and resistance to moisture. They are commonly used in various settings, including homes, hospitals, hotels, and other commercial spaces.
Nonwoven fabrics are engineered fabrics that may be single-use, have a limited life, or be very durable. Nonwoven fabrics provide specific functions such as absorbency, liquid repellence, resilience, stretch, softness, strength, flame retardancy, washability, cushioning, thermal insulation, acoustic insulation, filtration, use as a bacterial barrier and sterility. These properties are often combined to create fabrics suited for specific jobs, while achieving a good balance between product use-life and cost. They can mimic the appearance, texture and strength of a woven fabric. The advantage is that they are non-porous and thus can replace cloth curtains as an alternate to provide an easily cleanable surface that will not be harmed by cleaning materials such as hydrogen peroxide or bleach.
The curtain hardware (quick-release mechanism 149, a curtain attachment assembly or curtain holders 160, locking mechanism 80 and a retainer such as 500, grommets and curtain snaps 105) may be made using polypropylene beads and additive beads, for example, through the injection molding process using a technique called “foamed injection molding” or “muCell® injection molding.” In this process, the polypropylene and additive beads are expanded with a gas to create a foamed or cellular structure within the material. The foamed polypropylene then undergoes injection molding to produce the desired parts. The following are typical steps:
Polypropylene bead and additive bead preparation: Polypropylene beads and additive beads, also known as resin pellets or microspheres, are first loaded into the hopper of an injection molding machine.
Gas injection: During the injection molding process, a physical blowing agent or gas (such as nitrogen or carbon dioxide) is introduced into the polymer melt. The gas is typically injected into the molten polypropylene at high pressure, causing the beads to expand and creating a cellular structure within the material.
Mold filling: The foamed polypropylene and additive is injected into the mold cavity under pressure. The mold is designed to match the desired shape of the part being produced.
Cooling and solidification: Once the mold cavity is filled, the foamed polypropylene and additive cools and solidifies within the mold, taking the shape of the mold cavity.
Part ejection: After the material has solidified sufficiently, the mold opens, and the foamed polypropylene part is ejected from the mold.
Advantages of foamed injection molding using polypropylene beads and additive bead:
Lightweight: The cellular structure created by foaming the polypropylene results in a lighter weight part compared to solid injection-molded parts, making it suitable for applications where weight reduction is essential.
Reduced material usage: The foaming process allows for a reduction in the amount of polypropylene and additive material required to produce the same-sized part, leading to potential cost savings.
Improved mechanical properties: Foamed polypropylene parts can exhibit enhanced mechanical properties, such as increased impact resistance and energy absorption.
Enhanced insulation: The cellular structure provides improved thermal and acoustic insulation properties, making foamed polypropylene suitable for applications requiring insulation.
It's worth noting that while foamed injection molding offers various benefits, the process is more complex and requires specific equipment and expertise compared to traditional injection molding using solid polypropylene resins. As with any manufacturing process, careful optimization and control are essential to achieve desired properties and consistency in the final parts.
In addition to “foamed injection molding”, polypropylene beads and additive beads can be injection molded using different techniques, depending on the specific requirements of the final product and the desired properties. Here are some of the different ways polypropylene beads may be injection molded:
Conventional Injection Molding: In conventional injection molding, the polypropylene beads are heated until they melt and then injected into a mold cavity under high pressure. The mold is typically made of two halves, and the molten polypropylene fills the cavity to take the shape of the final product. Once the material cools and solidifies, the mold opens, and the part is ejected.
Gas-Assisted Injection Molding (GAIM): In gas-assisted injection molding, the polypropylene beads are injected into the mold cavity while a controlled amount of gas is simultaneously introduced. The gas displaces the molten plastic, pushing it against the mold walls and hollowing out the center of the part. This process is often used to create parts with thick walls, reducing material usage and cycle times.
Structural Foam Injection Molding: In structural foam injection molding, a blowing agent is mixed with the melted polypropylene beads before injection. The blowing agent creates a cellular structure within the material, similar to foamed injection molding. Structural foam molding produces parts with a smooth surface finish and enhanced strength-to-weight ratio.
Gas Counter Pressure Injection Molding (GCPIM): In GCPIM, the mold cavity is partially filled with polypropylene beads, and then a gas (often nitrogen) is injected to apply counter pressure against the material, preventing it from expanding beyond the desired shape. This process can help improve the surface finish and reduce sink marks in thick-walled parts.
Thermoset Injection Molding: While polypropylene is a thermoplastic material, some formulations of polypropylene can be modified to behave like a thermoset during injection molding. This involves adding special additives to the polymer that cause it to crosslink and harden permanently upon heating, similar to thermoset materials like epoxy.
Each of these injection molding techniques has its advantages and is chosen based on the specific requirements of the part, production volume, cost considerations, and the desired properties of the final product. Manufacturers often optimize the molding process and material formulation to achieve the best results for a particular application.
Although the disclosed:

- a. curtain 180 and second curtain or mesh 181; and
- b. the curtain hardware (quick-release mechanism 149, a curtain holder 160, locking mechanism 80, a retainer 500, grommets and snaps 105) are each made from the same material, polypropylene beads and additive beads, they are made using different manufacturing processes resulting in different durometer hardness.

Durometer hardness is a measure of the material's resistance to indentation. It is commonly used to assess the hardness of polymers and elastomers. The durometer hardness is measured using an instrument called a durometer, and the result is expressed as a number on a scale.
As described above, injection-molded polypropylene and additive is made using a manufacturing process used to produce solid parts by injecting molten plastic into a mold. The cooling and solidification of the plastic in the mold result in a relatively dense and rigid material. Injection-molded polypropylene products tend to have a higher durometer hardness because of the tightly packed polymer chains during the molding process.
Non-woven polypropylene: Non-woven polypropylene, on the other hand, is a fabric-like material made by bonding fibers together through mechanical, thermal, or chemical processes. Non-woven polypropylene products, such as the curtains are softer and more flexible compared to injection-molded polypropylene due to their fibrous nature and the way the fibers are entangled.
The durometer hardness of non-woven polypropylene will generally be lower than that of injection-molded polypropylene. However, it's important to note that the actual hardness can vary depending on the specific manufacturing processes and additives used in the production of each material. Different grades and formulations of polypropylene can result in variations in hardness, even within the same category of material. In the embodiments of the invention, it is important that the curtain hardware quick-release mechanism 149, a curtain attachment assembly or curtain holder 160, locking mechanism 80 and a retainer such as 500, grommets and snap(s) 105) are much more rigid than the curtains and curtain 180 and second curtain or mesh 181 so that the curtain hardware may firmly hold the curtain in place. For example, the locking mechanism 80 required many prototypes and revisions to arrive at a material thickness, rigidity and hardness to click and hold when in a raised position to hold into place. The more important or desirable curtain hardware that will be used for the disposable is the curtain holder 160, retainer 500 and snaps 105. These are the hardware components that will most frequently be thrown in a landfill when the curtains are replaced. Curtain hardware will range between Shore D 45 to Shore D60 with a desired range of Shore D 50 to Shore D55 wherein in this range it will strike a balance between flexibility and stiffness. While offering a good durability and still maintaining some flexibility, making them suitable for various curtain hardware applications.
In contrast, curtains are softer and more pliable and would be on the Shore A scale which is used to measure the hardness of soft pliable material. Shore A 30 to Shore A 70: Parts with durometer values in this range are considered relatively soft and flexible. They offer good flexibility, drape, and conformability, making them suitable for applications where softness and comfort are essential.
Shore A 40 to Shore A 60: Parts with durometer values in this range are moderately soft and still maintain some resilience. They are commonly used in nonwoven polypropylene products like disposable garments, wipes, and some types of bags.
Shore A 50 and below: Parts with durometer values in this range are very soft and pliable. Nonwoven polypropylene parts with such low hardness values are often used in applications where the material needs to be gentle against the skin, such as in medical products like surgical drapes or masks. The curtains of the embodiments of the present invention would have a Shore A 50 to Shore 70 hardness.
One embodiment of the invention would include adding an antimicrobial to the manufacturing process. The most common additives used to manufacture antimicrobial plastics include various isothiazolinone treatments, zinc pyrithione, thiabendazole, and silver antimicrobial products. Each active ingredient has its strengths and weaknesses.
The biodegradable composition may be used for a hospital disposable such as curtains (e.g. privacy or shower curtains), curtain hardware, surgical gowns, facemasks, disposable syringes, membranes for membrane oxygenators, connectors, finger-joint prostheses, non-absorbable sutures, pouches, test tubes, beakers, pipettes, reusable plastic containers, pharmacy prescription bottles and clear bags is disclosed. These are examples of hospital disposables that are creating a concern for disposal in landfills.
Although polypropylene is the desired material in combination with a biodegradable additive, an aspect disclosed in embodiments of the invention are hospital disposables made of one or more non-biodegradable polymer (e.g. polyethylene (PE), polypropylene (PP), and/or polyvinylchloride (PVC)) and an additive comprising a blend or copolymer of (1) a first polymer selected from a poly-lactic acid (PLA) and/or a polyhydroxyalkanoates (PHA) and (2) a second polymer which is a poly-terephthalate. In one embodiment, the first polymer and second polymer are covalently bound to one another to form a copolymer. In another embodiment, the first polymer and second polymer are blended together to form an admixture but are not covalently bound to one another.
In one embodiment, the non-biodegradable polymer is present in the hospital disposable at a concentration of 90-99.9 wt. %, at a concentration of 95-99.5 wt. %, at a concentration of 98-99.5 wt. % or at a concentration of 99 wt. %, with the mass balance being the additive. In such embodiments, the additive is present at a concentration of 0.1-10 wt. %, 0.5-5 wt. %, 0.5-2 wt. % and 1% wt. %, respectively.
The first polymer is a PLA, a PHA or a combination thereof. The term PLA includes poly-D-lactic acid (PDLA), poly-L-lactic acid (PLLA) and combinations thereof. Specific examples of PHAs include poly-3-hydroxybutyrate (PHB), poly-3-hydroxybutyrate-co-4-hydroxybutyrate (P (3-HB-co-4-HB)), poly-3-hydroxybutyrate-co-valerate (PHBV), and polyhydroxybutyrate-co-hexanoate (PHBH). In one embodiment, the first polymer is PLA sold under the brand name INGEO® and has a number-average molecular weight of 127 kg per mole and a polydispersity index of 1.6. In other embodiments, the number-average molecular weight is between 100-150 kg per mole.
The second polymer is a poly-terephthalate. Examples include copolymers such as polybutylene adipate terephthalate (PBAT), polybutylene terephthalate, polycyclohexylenedimethylene terephthalate, polyethylene terephthalate, polytrimethylene terephthalate, poly(butylene succinate terephthalate) (PBST) and poly(butylene sebacate terephthalate). In one embodiment, the second polymer is a PBAT polymer sold under the brand name ECOFLEX® and has a number-average molecular weight of about 52 kg per mole and a polydispersity index of 2. In other embodiments, the number-average molecular weight is between 40 and 60 kg per mole.
In one embodiment, the additive comprises a blend of 30-70 wt. % of the first polymer and 30-70 wt. % of the second polymer. In another embodiment, the additive comprises a blend of 40-60 wt. % of the first polymer and 40-60 wt. % of the second polymer. In another embodiment, the additive comprises a blend of 45-55 wt. % of the first polymer and 45-55 wt. % of the second polymer. In another embodiment, the additive comprises a blend of 49-51 wt. % of the first polymer and 49-51 wt. % of the second polymer. In yet another embodiment, the additive consists of a blend of 49-51 wt. % of the first polymer and 49-51 wt. % of the second polymer.
In one embodiment, the second polymer is a blend/admixture of a polyester (1) and a poly-terephthalate (2), the structure of which are shown below. In another embodiment, the second polymer is a copolymer prepared by transesterifying polyester (1) and poly-terephthalate (2). The values of a, b and c are integers independently selected from 1-8. In one embodiment, a and c are integers from 1-6 and b is an integer from 1-8. In one embodiment, a and c are both 4. In one embodiment, b is an integer from 1-4. In another embodiment, b is an integer from 5-8. In one embodiment, the values of a, b and c are all four. The transesterification is performed using conventional methods including acid catalyzed transesterification. Organometallic catalysts are known for facilitating such a reaction including tetrabutoxytitanium and other zinc, tin and germanium-based catalysts. The tranesterification may be performed at high temperature (e.g. greater than 190° C.) and under vacuum to facilitate removal of volatile byproducts, including water. During transesterification, random block copolymerization of the monomeric units may occur.
In one embodiment, a=b=c=4 and the poly-terephthalate (2) is polybutylene adipate terephthalate (PBAT).
In one embodiment, the values of m and n are within 30% of one another (e.g. a men molar ratio of 1.3:1 to a ratio of 1:1.3. In another embodiment, the values of m and n are within 20% of one another (e.g. a m:n ratio of 1.2:1 to 1:1.2). In another embodiment, the values of m and n are within 10% of one another (e.g. a m:n ratio of 1.1:1 to 1:1.1). In another embodiment, the values of m and n are within 5% of one another (e.g. a m:n ratio of 1.05:1 to 1:1.05). In another embodiment, the values of m and n are within 1% of one another (e.g. a m:n ratio of 1.01:1 to 1:1.01). In one embodiment, the terephthalate monomer is present in the additive at a concentration of less than 55 mol %.
The polyester (1) may be prepared from an alkane diol (3) and a diacid (R₁═H) (4). In one embodiment, R₁in the diacid (4) is methyl, ethyl or propyl such that a corresponding diester is used. In one embodiment, a is four such that compound (3) is 1,4-butane diol. In some embodiments, R₁is hydrogen and b is four (adipic acid), two (succinic acid) or eight (sebacic acid).
In one embodiment, R₁is hydrogen and b is four (i.e. adipic acid) and a is four (i.e. 1,4-butane diol) as shown below.
The poly-terephthalate (2) is prepared from a terephthalate ester (5) (or its corresponding acid) and alkane diol (6). In terephthalate ester (5) R₁may be H or an alkane such as methyl, ethyl, propyl, isopropyl, etc. The value of c is an integer from 1-6. In one embodiment, c is four such that compound (6) is 1,4-butane diol.
In one embodiment, R₁is methyl and c is four, as shown below.
The additive has a crosslinking density that renders it biodegradable. In one embodiment, the crosslinking density is less than 30%, less than 20% or less than 10%. The crosslinking density can be determined by using ASTM-D2765. This method determines gel content and swell ratio for a known mass of polymer extracted with a suitable solvent. The extracted material is separated from the solvent and weighed after drying. The higher the mass of extracted material, the lower the crosslinking density.
The additive has a glass transition temperature (T_g) within or below the optimal temperature of mesophilic bacteria (e.g. a T_gwithin a temperature range of 20° C. to 45° C.).
In particular embodiments, the hospital disposable such as curtains 180 and curtain hardware comprises a polypropylene (as the non-biodegradable polymer) and an additive comprising a blend of poly-L-lactic acid (PLLA) and a poly-terephthalate. Another aspect is a hospital disposable made of 90-99.9 wt. % polypropylene and 0.1-10 wt. % of a blend of poly-L-lactic acid and a poly-terephthalate, or 95-99.5 wt. % polypropylene and 0.1-5 wt. % of a blend of poly-L-lactic acid and a poly-terephthalate, or 98-99.5 wt. % polypropylene and 0.1-2 wt. % of a blend of poly-L-lactic acid and a poly-terephthalate, or 99 wt. % polypropylene and 1 wt. % of a blend of poly-L-lactic acid and a poly-terephthalate.
A further aspect of the embodiments is an additive for use with polypropylene comprising a blend of 30-70 wt. % poly-L-lactic acid and 30-70 wt. % poly-terephthalate, or an additive for use with polypropylene comprising a blend of 40-60 wt. % poly-L-lactic acid and 40-60 wt. % poly-terephthalate, or an additive for use with polypropylene comprising a blend of 45-55 wt. % poly-L-lactic acid and 45-55 wt. % poly-terephthalate, or an additive for use with polypropylene comprising a blend of 49-51 wt. % poly-L-lactic acid and 49-51 wt. % poly-terephthalate.
Another aspect is a method of making a hospital disposable comprising the steps of: blending polypropylene with an additive of poly-L-lactic acid and a poly-terephthalate; and at least one of extruding, molding and forming a hospital disposable from the blend.

Example 1

99 wt. % polypropylene solid beads were homogenously mixed/blended with 1 wt. % additive of solid beads comprised of 51 wt. % poly-L-lactic acid (PLLA) polymer and 49 wt. % poly(butylene adipate-co-terephthalate) (PBAT), or a copolymer of the two for 5 minutes. The mixture/blend was then injection molded into curtain hardware and curtain hangers.

Example 2

99 wt. % polypropylene solid beads were homogenously mixed/blended with 1 wt. % additive of solid beads comprised of 51 wt. % poly-L-lactic acid (PLLA) polymer and 49 wt. % poly(butylene adipate-co-terephthalate) (PBAT), or a copolymer of the two for 5 minutes. The mixture/blend was then extruded into a flame-retardant, nonwoven 115 grams per square meter (gsm) polypropylene curtain.
The hardware produced by Example 1 was then assembled onto the curtain of Example 2 to provide a biodegradable curtain and hardware.
Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.
For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements. The mention of a “unit” or a “module” does not preclude the use of more than one unit or module.

Biodegradation Testing

The injection molded plastic was tested under standard ASTM D5511. This test method covers the determination of the degree and rate of anaerobic biodegradation of plastic materials in high-solids anaerobic conditions. The test materials are exposed to a methanogenic inoculum derived from anaerobic digesters operating only on pretreated household waste. The anaerobic decomposition takes place under high-solids (more than 30% total solids) and static non-mixed conditions. This test method is designed to yield a percentage of conversion of carbon in the sample to carbon in the gaseous form under conditions found in high-solids anaerobic digesters, treating municipal solid waste.
Anaerobic digested sewage sludge was mixed with household waste. To make the sludge adapted and stabilized during a short post-fermentation at 53° C., the sludge was pre-incubated (one week) at 53° C. This means that the concentrated inoculum was not fed but allowed to post ferment the remains of previously added organics allowing large easily biodegradable particles were degraded during this period and reduce the background level of biogas from the inoculums itself.
A sample of the anaerobic digested sewage sludge was analyzed for pH, percent dry solids, and volatile solids, as well as, the amount of CO2 and CH4 evolution during the testing. Table 1 lists the results of this initial testing.
Inoculum Medium: Remove enough inoculum (approximately 15 kg) from the post-fermentation vessel and mix carefully and consistently by hand in order to obtain a homogeneous medium. Test three replicates each of a blank (inoculum only), Positive control (Reference material) (thin-layer chromatography cellulose), negative control (optional), and the test substance being evaluated.
Manually mix 1000 g wet weight (at least 20% dry solids) of inoculum in a small container for a period of 2 to 3 min with 15 to 100 g of volatile solids of the test substance or the controls for each replicate. For the three blanks containing inoculum only, manually mix 1000 g of the same inoculum in a small container for a period of 2 to 3 min with the same intensity as was done for the other vessels containing test substance or controls. Determine the weight of the inoculum and test substance added to each individual Erlenmeyer flask accurately. Add the mixtures to a 2-L wide-mouth Erlenmeyer flask and gently spread and compact the material evenly in the flask to a uniform density.
After placing the Erlenmeyer flask in incubator, connect it with the gas collection device. Incubate the Erlenmeyer flasks in the dark or in diffused light at 52° C. (±2° C.) for thermophilic conditions, The incubation time shall be run until no net gas production is noted for at least five days from both the Positive control (Reference material) and test substance reactors. Control the pH of the water used to measure biogas production to less than two by adding HCl.
The most important biochemical characteristics of the inoculum such as pH, Volatile Fatty Acids, NH4+−N—and dry solids were studied.

TABLE 1

Results of Initial testing of the anaerobic digested sewage sludge

Parameters	Requirement	Actual results

pH	7.5 to 8.5	7.85
Kjeldahl nitrogen	0.5 to 2 g/kg wet weight	1.46
Dry Solids at 105° C.	>20%	44.00
Volatile Solids at 550° C.	Below 1 g/kg wet weight	0.76

The biogas volume in the gas sampling bag was measured (Table—2). Presence of gas in the gas collector of Positive control indicated that the inoculum was viable and gas displacement was observed both in Positive control and Test Sample.
ASTM D5511 states that for the test to be considered valid, the Positive control must achieve 70% within 30 days with deviation less than 20% of the mean between the replicates.
Positive control (Reference material) showed 71.03% on 27th day with less than 20% of the mean difference between the replicates.
The gas displacement observed after 90 days is as shown in the table below.

TABLE 2

Biogas volume of the evolved gas during
the biodegradation process at 90 days

	Biodegradation	Total Volume
	Test
	90 days (mL)

	Inoculum	2840
	Positive control (Reference material)	10100
	Bioplastic	6500

The percent biodegradation of Positive control (and Test sample was calculated by the measured cumulative carbon dioxide and methane production from each flask after subtracting carbon dioxide evolution and methane evolution from the blank samples at the end 90 days of testing. Calculations were based on Total Organic Carbon obtained of both Positive control and Test sample.

TABLE 3a

Percentage biodegradability of Test sample
with respect to Positive control

		Positive control	Biodegradable
	Inoculum	(Reference	plastic
Cellulose. Group	control	material)	Sample

Weight	1000 ml	10.2305 g	10.1335 g
Total volume (ml)	2840.00	10100.00	6500.00
% CH4	13.20	44.90	21.80
Volume of CH4	374.88	4534.90	1417.00
(ml)
weight of CH4 (g)	0.2459	2.9749	0.9296
% CO2	15.70	45.50	24.20
Volume of CO2 (ml)	445.88	4595.50	1573.00
Weight of CO2 (g)	0.8828	9.0991	3.1145
Total weight of	0.4228	4.6879	1.5381
carbon in grams
Theoretical weight	—	4.3040	8.4999
of carbon in grams
(Ci)
Biodegradation	—	0.99097	0.13121
% Biodegradation	—	99.10	13.12

Based upon the above, the biodegradable polymer/plastic showed a 13.12% biodegration over 90 days. This satisfies the ASTM D5511 standards for biodegradation.
Although the present invention has been disclosed in the form of preferred embodiments and variations thereon, it will be understood that numerous additional modifications and variations could be made thereto without departing from the scope of the invention.
For the sake of clarity, it is to be understood that the use of “a” or “an” throughout this application does not exclude a plurality, and “comprising” does not exclude other steps or elements.

Claims

What is claimed is:

1. A biodegradable hospital privacy curtain comprising:

a curtain comprised of:

a non-biodegradable polymer; and

an additive comprising a blend or copolymer of (1) a first polymer selected from a poly-lactic acid (PLA), a polyhydroxyalkanoates (PHA) or a combination thereof and (2) a second polymer which is a poly-terephthalate.

2. Biodegradable hospital privacy curtain hardware comprising: curtain hardware comprised of:

a non-biodegradable polymer; and

3. The biodegradable hospital privacy curtain hardware of claim 1 wherein the curtain hardware is selected from:

a curtain holder, a retainer, a grommet and a snap.

4. A biodegradable hospital privacy curtain and curtain system comprising:

a. a curtain; and

b. curtain hardware, wherein one or both the curtain and curtain hardware are made from a material comprised of:

i. a non-biodegradable polymer; and

ii. a biodegradable additive,

wherein the curtain has a first hardness on the durometer scale and the curtain hardware has a second hardness on the durometer scale, different than the first hardness on the durometer scale.

5. The biodegradable hospital privacy curtain and curtain system of claim 1, wherein the curtain and curtain hardware are made of the same material.

6. The biodegradable hospital privacy curtain and curtain system of claim 1, wherein the curtain has a hardness of Shore A 50 to Shore 70 hardness.

7. The biodegradable hospital privacy curtain and curtain system of claim 1, wherein the curtain hardware has a Shore D 45 to Shore D60 hardness.

8. A biodegradable hospital privacy curtain and curtain system comprising:

a. a curtain; and

b. curtain hardware, wherein the curtain and curtain hardware comprise a non-biodegradable polymer selected from a group consisting of polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC) and combinations thereof; and

c. an additive comprising a blend or copolymer of (1) a first polymer selected from a poly-lactic acid (PLA), a polyhydroxyalkanoates (PHA) or a combination thereof and (2) a second polymer which is a poly-terephthalate.

9. The biodegradable hospital privacy curtain and curtain system of claim 5, wherein the non-biodegradable polymer is present in a concentration from 90-99.9 wt. %, the additive is present in a concentration from 0.1-10 wt. % and the additive has 30-70 wt. % of the first polymer and 30-70% of the second polymer.

10. The biodegradable hospital privacy curtain and curtain system of claim 1, further comprising:

an antimicrobial additive.

11. The biodegradable hospital privacy curtain and curtain system of claim 7, wherein the antimicrobial is selected from isothiazolinone treatments, zinc pyrithione, thiabendazole, and silver.

12. The biodegradable hospital privacy curtain of claim 5, wherein the curtain and curtain hardware have different durometer hardnesses.

13. A method of making a hospital disposable, the method comprising

a. adding 0.1 to 10 wt. % of an additive consisting of a biodegradable polymer to a mass of solid 90-99.9 wt. % polypropylene beads, thereby producing an admixture of the solid polypropylene beads and the additive;

b. mixing the admixture until a homogenous mixture is produced; and

c. forming the homogenous mixture into a hospital disposable.

14. The method as recited in claim 13, wherein the forming comprises injection molding the homogenous mixture into curtain hardware and/or curtain hangers.

15. The method as recited in claim 13, wherein the forming comprises extruding the homogenous mixture into a flame-retardant, nonwoven 115 grams per square meter (gsm) polypropylene curtain.

16. The method of claim 13, wherein the hospital disposable is selected from a group consisting of a curtain, a curtain hardware, a surgical gown, a facemask, a disposable syringes a membrane for a membrane oxygenator, a connector, a finger-joint prosthesis, a non-absorbable suture, a pouch, a test tube, a beaker, a pipette, a reusable plastic container and a pharmacy prescription bottle.

17. A biodegradable hospital privacy curtain of claim 1, wherein the non-biodegradable polymer is selected from a group consisting of polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC) and combinations thereof.

18. A biodegradable hospital privacy curtain of claim 2, wherein the non-biodegradable polymer is selected from a group consisting of polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC) and combinations thereof.

19. A biodegradable hospital privacy curtain of claim 4, wherein the non-biodegradable polymer is selected from a group consisting of polyethylene (PE), polypropylene (PP), polyvinylchloride (PVC) and combinations thereof.

20. The method of claim 13, further comprising:

the step of forming further comprises extruding the homogenous mixture;

d. bonding the web of filaments to create a cohesive non-woven fabric;

e. cutting and sewing the web into the shape of a curtain; and

f. attaching curtain hardware to the curtain.