U.S. patent application number 10/376993 was filed with the patent office on 2003-11-13 for instrument sterilization container having improved diffusion.
Invention is credited to Howlett, Charles, Wu, Su-Syin.
Application Number | 20030211023 10/376993 |
Document ID | / |
Family ID | 24700061 |
Filed Date | 2003-11-13 |
United States Patent
Application |
20030211023 |
Kind Code |
A1 |
Wu, Su-Syin ; et
al. |
November 13, 2003 |
Instrument sterilization container having improved diffusion
Abstract
A sterilization container for sterilizing, storing and
transporting instruments provides enhanced diffusion. Cut-out
portions of the lid sidewalls and base sidewalls interact to form
openings through the side of the container. Apertures are also
preferably formed through upper and lower surfaces of the
container. Such design is particularly useful when the container is
formed of a liquid crystal polymer, such as a wholly aromatic
polyester.
Inventors: |
Wu, Su-Syin; (Irvine,
CA) ; Howlett, Charles; (Laguna Beach, CA) |
Correspondence
Address: |
AUDLEY A. CIAMPORCERO JR.
JOHNSON & JOHNSON
ONE JOHNSON & JOHNSON PLAZA
NEW BRUNSWICK
NJ
08933-7003
US
|
Family ID: |
24700061 |
Appl. No.: |
10/376993 |
Filed: |
February 28, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10376993 |
Feb 28, 2003 |
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10114212 |
Apr 2, 2002 |
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10114212 |
Apr 2, 2002 |
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08672802 |
Jun 28, 1996 |
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6379631 |
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Current U.S.
Class: |
422/297 ;
422/300 |
Current CPC
Class: |
A61L 2/206 20130101;
A61L 2202/182 20130101; A61L 2/07 20130101; A61L 2/14 20130101;
A61L 2202/24 20130101; A61L 2/26 20130101; A61L 2/208 20130101;
A61L 2202/122 20130101 |
Class at
Publication: |
422/297 ;
422/300 |
International
Class: |
A61L 002/00; A61L
009/00 |
Claims
We claim:
1. A sterilization container for sterilizing instruments,
comprising: a base having upwardly projecting sidewalls terminating
in an upper edge; a lid receivable upon the base and having
downwardly depending sidewalls terminating in a lower edge; the lid
and base forming an enclosure; and wherein the lid sidewalls
comprise a plurality of cut-out portions at the lower edge and the
base sidewalls comprise a plurality of cut-out portions at the
upper edge with the lid sidewall cut-out portions and base sidewall
cut-out portions being in registry with each other to create a
plurality of openings into the enclosure.
2. A sterilization container according to claim 1 wherein the lid
sidewall cut-out portions are widest at the lower edge.
3. A sterilization container according to claim 1 wherein the base
sidewall cut-out portions are widest at the upper edge.
4. A sterilization container according to claim 1 wherein the base
and lid are formed of a thermoplastic liquid crystal polymer
whereby the base and lid resist chemical attack from hydrogen
peroxide, and ethylene oxide, the wall does not unduly interfere
with any electromagnetic fields, and the wall resists attack from
elevated temperatures.
5. A sterilization container according to claim 4 wherein the
thermoplastic liquid crystal polymer comprises a wholly aromatic
polyester.
6. A sterilization container according to claim 5 wherein the
wholly aromatic polyester is selected from the group consisting of:
polybenzoate-naphthalate;
polybenzoate-terephalate-bisphenol-isophthalate- ;
polybenzoate-terephalate-ethylene glycol; and polynapthalate-amino
terephthalate.
7. A sterilization container according to claim 1 and further
comprising means for holding a medical instrument against movement
within the enclosure.
8. A sterilization container according to claim 1 and further
comprising a first plurality of apertures through a lower surface
of the base.
9. A sterilization container according to claim 8 and further
comprising a second plurality of apertures through an upper surface
of the lid.
10. A sterilization container according to claim 1 and further
comprising a filtering material filtering ingress and egress of
material from the container, the filtering material being permeable
to a gas or vapor sterilizing media but impermeable to
microorganisms.
11. A sterilization container according to claim 10 wherein the
filtering material comprises a wrappable material wrapped about the
container.
12. A sterilization container according to claim 1 and further
comprising a plurality of projections on the lid facing and
abutting the base sidewall upper edge whereby to enhance diffusion
into the container between the lid and the base.
Description
[0001] This is a continuation of prior application Ser. No.
10/114,212 filed Apr. 2, 2002 which is a continuation of
application Ser. No. 08/672,802 filed Jun. 28, 1996.
BACKGROUND
[0002] 1. Field of the Invention
[0003] This invention relates to a sterilization container for use
in sterilizing, storing and transporting and presenting
instruments, in particular medical instruments.
[0004] 2. Background of the Invention
[0005] Most, reusable medical instruments require sterilization
before each use. Many methods are employed for sterilization, but
the most prevalent methods include: steam autoclaving, vapor phase
chemical sterilization and vapor phase chemical sterilization in
combination with a plasma field. The chemical sterilants include
hydrogen peroxide and ethylene oxide. One of the most versatile,
quickest and most effective methods employs an initial period of
vapor phase hydrogen peroxide followed by application of an
electromagnetic field which drives the hydrogen peroxide vapor into
the plasma state of matter. The plasma phase enhances the
sterilization and when the electromagnetic field is released the
plasma free radicals recombine to form water and oxygen.
[0006] Typically, instruments are placed into a container and then
the container is placed into the sterilization device. Portals for
the passage of sterilizing media must be provided. Also, the
container is usually provided with a filter material which allows
passage of the sterilizing media through the portals and container
yet prevents the ingress of microorganisms. The portal and filter
material may be combined as in the Nichols U.S. Pat. No. 4,704,254,
issued Nov. 3, 1987 and incorporated herein by reference, or the
container may be provided with a plurality of apertures and then be
wrapped prior to each sterilization in a filter wrapping material
such as SPUNGUARD brand CSR wrap available from Kimberly Clark
Corporation which is a spunbonded/meltblown/spunbonde- d (SMS)
laminate consisting of nonwoven outer layers of spun-bonded
polyolefins and an interior barrier layer of melt-blown
polyolefins.
[0007] Usually, holding devices of one form or another hold one or
more individual instruments within the container. The holding
device may comprise clips or other such arrangements, which may or
may not be specially adapted to hold a particular medical
instrument. One popular holding device simply comprises a plurality
of upwardly extending flexible projections, sometimes called
fingers, which prevent the instruments from moving about within the
container and provide minimal contact with the instruments.
Typically, these are provided on a mat which lies in the bottom of
the container.
[0008] The ideal sterilization tray or container is compatible with
all major sterilization methodologies, minimizes or eliminates
condensation collection through thin, yet strong, walls, has a long
life, is easy to operate and can be provided for a reasonable cost.
Containers presently known suffer from shortcomings which limit
their performance in one or more of these areas. For instance, many
trays designed for steam autoclaves are formed of stainless steel
which may interfere with formation of a plasma in some systems.
Other trays made of polymers may not have sufficient heat
resistance to withstand repeated steam sterilization cycles. Some
tray materials interact with chemical sterilants, and may even
decompose the sterilant. Other materials may absorb excessive
amounts of chemical sterilants, thereby decreasing the
sterilization effectiveness by decreasing the amount of sterilant
available for sterilizing.
SUMMARY OF THE INVENTION
[0009] The present invention provides a sterilization container
with enhanced diffusion. According to the present invention, a
sterilization container for sterilizing instruments comprises a
base having upwardly projecting sidewalls terminating in an upper
edge and a lid receivable upon the base and having downwardly
depending sidewalls terminating in a lower edge. The lid and base
form an enclosure. The lid sidewalls comprise a plurality of
cut-out portions at the lower edge and the base sidewalls comprise
a plurality of cut-out portions at the upper edge with the lid
sidewall cut-out portions and base sidewall cut-out portions being
in registry with each other to create a plurality of openings into
the enclosure.
[0010] Preferably, the lid sidewall cut-out portions are widest at
the lower edge and the base sidewall cut-out portions are widest at
the upper edge. In one preferred embodiment the base and lid are
formed of a thermoplastic liquid crystal polymer whereby the base
and lid resist chemical attack from hydrogen peroxide, and ethylene
oxide, the wall does not unduly interfere with any electromagnetic
fields, and the wall resists attack from elevated temperatures.
Preferably, the thermoplastic liquid crystal polymer comprises a
wholly aromatic polyester, and more preferably is selected from the
group consisting of: polybenzoate-naphthalate;
polybenzoate-terephalate-bisphenol-isophthalate- ;
polybenzoate-terephalate-ethylene glycol; and polynapthalate-amino
terephthalate.
[0011] Preferably, the sterilization container further comprises
means for holding a medical instrument against movement within the
enclosure, a first plurality of apertures through a lower surface
of the base, and a second plurality of apertures through an upper
surface of the lid.
[0012] Preferably, the sterilization container further comprises a
filtering material filtering ingress and egress of material from
the container, the filtering material being permeable to a gas or
vapor sterilizing media but impermeable to microorganisms. One
preferred material is a wrappable material wrapped about the
container.
[0013] Preferably, the sterilization container further comprises a
plurality of projections on the lid facing and abutting the base
sidewall upper edge whereby to enhance diffusion into the container
between the lid and the base.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is an exploded, perspective view of a sterilization
container according to the invention;
[0015] FIG. 2 is a perspective view of the assembled sterilization
container of FIG. 1;
[0016] FIG. 3 is a perspective view of the inverted lid of the
sterilization container of FIG. 1;
[0017] FIG. 4 is a cross-section taken along lines 4-4 of FIG.
2;
[0018] FIG. 5 is a perspective, disassembly view of a portion of a
sterilization container according to the present invention which
illustrates an alternative latching mechanism according to the
present invention;
[0019] FIG. 6 is a cross-section of the latching mechanism of FIG.
5, with the latch shown in the closed position;
[0020] FIG. 7 is a perspective view of a further embodiment of a
sterilization tray according to the present invention;
[0021] FIG. 8 is a cross-section taken along line 8-8 of FIG.
7;
[0022] FIG. 9 is a perspective view of a stacking device according
to the present invention;
[0023] FIG. 10 is a side view of the stacking device of FIG. 9
positioned between two sterilization containers to stack and
separate the containers;
[0024] FIG. 11 is a perspective view of a further embodiment of a
stacking device according to the present invention; and
[0025] FIG. 12 is underside plan view of a further embodiment of a
lid according to the present invention.
DETAILED DESCRIPTION
[0026] FIG. 1 illustrates a first embodiment of a sterilization
container 10 according to the present invention. The container 10
comprises a tray 12, a mat 14, and a lid 16. The tray 12 comprises
a rectangular base 18 from which extends upwardly two opposing side
walls 20 and two opposing end walls 22. Corners 24 formed between
the side walls 20 and end walls 22 are rounded for a pleasing
appearance, improved strength, and to reduce sharp edges which may
compromise the integrity of an operator's protective rubber glove
(not shown). A fillet 26 between the base 18 and the side and end
walls 20 and 22 also enhances the strength of the tray 12.
[0027] The base 18 comprises a plurality of drainage wells 28, each
one comprising a downwardly sloping surface 30 terminating in a
drainage aperture 32. The sloping surfaces 30 of adjacent drainage
wells 28 intersect to form peaks 34. Preferably, the peaks 34 form
distinct lines or singularities, as opposed to rounded interfaces
between adjacent sloping surfaces 30. This minimizes the surface
areas of the peaks 34 which support the mat 14, thereby reducing
the area of contact between the base 18 and mat 14. Thus, little
space is provided in which condensate or other liquid matter may
become trapped.
[0028] The mat 14 has a plurality of mat apertures 38 therethrough
and a plurality of upwardly extending projections 36 for holding
medical instruments (not shown) that are to be sterilized within
the container 10. Apertures 38 on the mat 14 align with drainage
apertures 32 through the tray base 18. Preferably, the mat 14 is
formed of a silicone or other elastomeric substance which resists
high heat associated with steam autoclaving, and also resists
chemical attack from hydrogen peroxide, ethylene oxide, or other
chemical sterilants or their precursors, particularly the oxidizing
type sterilants. Further, the material of the mat 14 should not
absorb or chemically interact with such chemical sterilants.
[0029] The upwardly extending projections 36 may take several
forms. For instance, they may taper upwardly, or have constant
diameter. The tip may be flat, rounded or radiused. They may be
relatively soft or they may be rigid. The total number and spacing
of the projections 36 may also be varied. Such mats are known in
the art, and it is well within the ordinary skill of a practitioner
in the art to vary these design parameters to achieve a desired
overall effect.
[0030] The container lid 16 has a plurality of lid apertures 40 to
promote the passage of sterilizing vapors therethrough. The lid
apertures 40 may align with the drainage apertures in the tray 12,
but need not be so aligned. The lid 16 further comprises downwardly
depending sidewalls 42 and endwalls 44.
[0031] Turning also now to FIG. 2, the tray 12 and lid 16 are sized
so that the tray endwalls or sidewalls and endwalls 20 and 22 fit
snugly within the lid sidewalls and endwalls 42 and 44. Preferably,
a latching mechanism 46 is integrally formed in the tray 12 and lid
16. Each of the base endwalls 22 has a recessed portion 48. A pair
of U-shaped cutouts 50 in each recess portion 48 define a flexible
tang 52. An upper extent 54 of each tang 52 comprises a sloped
camming surface 56 and a retaining lip 58. Recessed portions 60 in
the lid 16 align with the endwall recesses 48 and comprise an
aperture 62 and retaining lip 64. To engage the latch mechanism 46,
the camming surface 56 on each tang 52 is inserted into the
corresponding aperture 62 in the lid 16 and cammed over the
retaining lip 64 until the retaining lip 58 on the tang 52 snaps
into engagement with the retaining lip 64. Inward pressure on the
tang 52, applied manually, disengages the retaining lips 58 and 64
to release the latch mechanism 46.
[0032] To enhance the flow of sterilizing gases through the
container 10, each of the tray sidewalls 20 and lid sidewalls 42
contain several shallow cutout portions 66. As best seen in FIG. 2,
when the lid 16 and tray 12 are interconnected, the cutout portions
66 thereon align with each other to form shallow slit-like openings
68 into the container 10. This enhances the flow of sterilizing
gases through the container 10.
[0033] Turning to FIG. 3, four pads 70 are provided inside of the
lid 16 to space the lid 16 from the tray 12 and thereby minimize
any surface contact area therebetween which might block the flow of
gas or liquid or which might trap, condensate, or other liquid
material.
[0034] FIG. 4 illustrates the drainage enhancing features of the
present invention. The peaks 34 of the base 18 support the flexible
mat 14. Condensate or other liquid which enters between the mat 14
and base 18 comes within one of the drainage wells 28. The small
contact surface 71 formed between the peaks 34 and mat 14 prevents
condensate or other liquids from being trapped between surfaces of
the base 18 and mat 14. The downwardly sloping surfaces 30 of the
drainage wells 28 encourage any condensate or other liquids to move
toward the drainage apertures 32. Condensate then physically drains
out of the container 10. The supporting characteristics of the
peaks 34 can not be over emphasized. Silicone and other elastomeric
materials suitable for forming the mat 14 tend to soften
considerably in high temperature sterilizing environments.
Accordingly, it is crucial to properly support the mat 14.
[0035] The selection of tray material for use in hydrogen peroxide
or chemical based sterilization technology is influenced by the
chemical resistance and inertness of the material with respect to
the sterilant or precursor for chemical plasma. For chemical plasma
sterilization methods which depend on excited free radicals, the
inertness of the material with respect to the plasma precursor is
even more critical due to possible low concentrations of precursor
available to generate plasma in some preferred plasma
methodologies. The tray material should be non-reactive to the
sterilant(s), or the precursor(s) for the chemical plasma in order
not to affect biological lethality of the sterilizer chamber. For
ease of operation, the material should also be resistant to the
chemical and thermal environments during the cleaning and
decontamination procedure of instruments and trays as commonly used
in clinical situations. Hospitals typically use a
washer/decontaminator operating at 270.degree. F. as well as
detergents and enzymatic cleaners for removing organic matter.
[0036] The ideal tray material should further be compatible with
all major sterilization methods employed by hospitals and the like,
including steam (flash and gravity), ethylene oxide gas, and
hydrogen peroxide based sterilizers. One example of the hydrogen
peroxide based plasma sterilization is the STERRAD Sterilization
System that uses hydrogen peroxide plasma to eliminate
microorganisms on medical instruments. Therefore, the ideal
material should have adequate thermo-mechanical properties to
withstand steam, exhibit low ethylene oxide residuals after
processing, and have extremely low interaction with H.sub.2O.sub.2
or other oxidative sterilants.
[0037] We have rigorously examined and tested many materials to
identify a material suitable for such varied and extreme service
environments. As a result of our investigations, we have found the
preferred materials to be neat (non-reinforced) and reinforced
polyester based liquid crystal polymers, neat and reinforced
polyesters, and reinforced polypropylene. The most preferred
material is neat or reinforced polyester liquid crystal polymer, or
its blend with the above mentioned polymers. One commercially
available example of a suitable liquid crystal polymer is the
Vectra.RTM. family produced by the Hoechst Celanese
Corporation.
[0038] Within each family group, there are preferred chemical
structures, either with or without reinforcement, which can be
considered as tray materials:
[0039] I. Reinforced polypropylene, especially when reinforced with
calcium carbonate or glass fiber, provides the chemical inertness
and structural properties required for multi-sterilization
application.
[0040] II. Polyester type polymers have a variety of basic
structures, among them:
[0041] 1. Polyethylene terephthalate (PET) with the following
chemical structure: 1
[0042] 2. Polybutylene terephthalate (PBT), in which chemical
structure is: 2
[0043] and
[0044] 3. Polycyclohexylene terephthalate (PCT), with the following
chemical structure: 3
[0045] PCT is available from Eastman Chemical Company under the
tradename of "Ektar", in a variety of unmodified and modified
structures. Modification may include acids and glycol
structures.
[0046] Among the polyester family, the structure of polyethylene
terephthalate is preferred. The most preferred configuration is
glass fiber reinforced PET. The fiber reinforcement provides
structural strength for steam autoclave operation and is preferred
in oxidative chemical vapor or oxidative chemical plasma
sterilization methods.
[0047] III. Liquid crystal polymers, in which there are four major
structural variations:
[0048] 1. Polybenzoate-naphthlate 4
[0049] An example of a commercially available product is under the
tradename VECTRA.RTM. A and C series by Hoechst Celanese
Corporation.
[0050] 2. Polybenzoate-terephthalate-bis phenol-isophthalate 5
[0051] An example of a commercially available product is under the
tradename of Xydar.RTM. by Amoco Performance Products.
[0052] 3. Polybenzonate-terephthalate-ethylene glycol 6
[0053] An example of a commercially available product is under the
tradename of X7G and X7H by Eastman Chemical Company and
[0054] 4. Polynaphthalate-amino terephthalate 7
[0055] An example of a commercially available product is under the
tradename of Vectra.RTM. B series by Hoechst Celanese
Corporation.
[0056] The most preferred structures are the wholly polyester
aromatic liquid crystal polymers, which are
polybenzoate-naphthalate and polybenzoate-terephthalate-bis
phenol-isophthalate. Both neat and reinforced grades are preferred
due to the structural strength of this material family. The most
preferred reinforcements fillers are glass or mineral fibers, or
fluoropolymers in powders, .
[0057] The material characteristics in a hydrogen peroxide
environment are of particular importance. Both the tendency to
absorb hydrogen peroxide and the tendency to decompose hydrogen
peroxide were studied for a variety of materials. The following
Table 1 illustrates the results for some of the more important
materials.
1TABLE 1 H.sub.2O.sub.2 H.sub.2O.sub.2 Material Material Absorption
Decomposition Tradename Family (ppm) (g/g) Ultem 1000
Polyetherimide 144.3 Ultem CRS 5011 Polyetherimide 346 Radel R-5100
Polyaryl sulfone 356 Noryl Polyphenylene 52 oxide/Polystyrene blend
Vectra A530 Polyester liquid 4.5 0.009 crystal polymer (mineral
fiber filled) Vectra A115 Polyester liquid no 0.013 crystal polymer
(glass absorption fiber filled) DPP40W18357 40% calcium no 0.012
carbonate absorption filled polypropylene Ektar EG-015 Glass fiber
filled poly 3.3 no ethylene terephthalate decomposition
[0058] Another study was conducted to evaluate the compatibility of
tray materials with simulated hydrogen peroxide plasma
sterilization and washer/decontamination cycles, which includes
alternating hydrogen peroxide plasma sterilization cycle,
washer/decontaminator cycle and enzymatic cleaner immersion. The
samples were placed under 0.5% and 0.75% strain. The following
Table 2 illustrates the results of this evaluation.
2TABLE 2 Strain Yield Tensile Elongation at Material Level Strength
Strength Break Ultem 1000 Control 15,320 psi 14,690 psi 68.5% Ultem
1000 0.5% 10,140 psi 10,140 psi 2.4% (a) Ultem 1000 0.75% 11,630
psi 11,230 psi 4.2% (a) Noryl Control 9,965 psi 7,852 psi 13.1%
Noryl 0.5% 10,400 psi 7,961 psi 9.3% Noryl 0.75% 10,550 psi 8,091
psi 98.5% Vectra A530 Control n/a 22,672 psi n/a Vectra A530 0.5%
n/a 22,371 psi n/a Vectra A530 0.75% n/a 22,431 psi n/a Vectra A115
Control n/a 24,265 psi n/a Vectra A115 0.5% n/a 23,266 psi n/a
Vectra A115 0.75% n/a 23,485 psi n/a DPP40WI Control 3,258 psi
2,699 psi 19.27% DPP40WI 0.5% 2,862 psi 2,449 psi 54.42%
[0059] Aside from using chemically inert material, there are other
controlling characteristics of sterilization trays or containers so
as to reduce interaction with the sterilization environment and so
as to enhance the resistance to hospital-use cleaning chemicals.
Interaction of tray material with the sterilants or precursor for
chemical plasma reduces the available sterilant or precursor for
chemical plasma in vapor phase so as to effect the biological
lethality. Resistance to hospital-use chemicals will lengthen the
expected product life. The first characteristic to be controlled is
the surface smoothness of final product. The surface of the
sterilization tray should be as smooth as possible so as to reduce
surface area/volume ratio. Since both chemical and physical
interactions with sterilants or precursor(s) for chemical plasma
and material degradation are a function of the surface area/volume
ratio, smooth surfaces will reduce the rate of these
interactions.
[0060] The second characteristic to be controlled is wall
thickness. Wall thickness is integral to the structural strength of
the tray or container. For the sterilization tray or container to
operate in an oxidative chemical vapor or chemical plasma
environment, often under reduced pressure and low concentration,
the condensation of chemical sterilant or precursor for chemical
plasma should be minimized. Condensation is a function of the
thermal mass and heat transfer characteristics of the tray or
container, which may reduce the amount of available sterilant or
precursor for chemical plasma in vapor phase and thereby effect the
biological lethality. To minimize the thermal mass and enhance the
heat transfer characteristics, the wall thickness of the tray or
container should be minimized.
[0061] Accordingly, the preferred materials for forming the tray 12
and lid 16 are as follows:
[0062] I. Reinforced polypropylene: Reinforced polypropylene,
especially when reinforced with calcium carbonate or glass fiber,
will provide the thermo-mechanical structural integrity required
for multi-sterilization application.
[0063] II. Neat or reinforced polyester: Among the polyester
family, the structure of polyethylene terephthalate is preferred.
The most preferred configuration is glass reinforced polyethylene
terephthalate (PET). The fiber reinforcement provides structural
strength for steam autoclave operation and allows for a thin-wall
design, which is preferred in oxidative chemical vapor
sterilization method.
[0064] III. Neat or reinforced liquid crystal polymer, and/or a
blend of the above materials. The most preferred structures are the
wholly polyester aromatic liquid crystal polymer, which can be of
the chemical structure of polybenzoate-naphthalate or
polybenzoate-terephthalate-bis phenol-isophthalate. Both neat and
reinforced grades are preferred due to the thermo-mechanical
strength of this material family. The most preferred reinforcements
types are glass and mineral fibers.
[0065] IV. A blend or alloy of liquid crystal polymers and I or II
of the above.
[0066] FIGS. 5 and 6 illustrate a second embodiment of a
sterilization container according to the invention. The container
72 comprises a tray 74, lid 76 and mat (not shown) similar to the
previous embodiment. However, it incorporate an alternative
latching mechanism 78.
[0067] The lid 76 comprises an apertured top wall 80; side and
endwalls 82 and 84, respectively, depending therefrom. A latch
member 86 is integrally molded into a recessed portion 88 in each
endwall 84 of the lid 76. A pair of torsion bars 90 extend inwardly
of the recess portion 88 from opposing sidewalls 92 thereof to
rotatably support the latch member 86. The torsion bars 90 bias the
latch member 86 into a standing, engaged position as shown best in
FIG. 6, and allow a limited amount of rotation away from the
engaged position.
[0068] A notch 94 in each endwall 96 of the tray 74 forms an
engagement surface 98. A lip 100 protruding from a lower portion
102 of the latch member 86 engages the engagement surface 98 on the
tray 74 to thereby hold the lid 76 securely to the tray 74. Finger
pressure against an actuation surface 104 on an upper portion 106
of the latch member 86 pivots the latch member 86 about the torsion
bars 90 to disengage the engagement surface 98 from the lip 100 and
thereby release the lid 76 from the tray 74. When the pressure on
the actuation surface 104 is release, the torsion bars 90 return
the latch member 86 to its standing, engaged position.
[0069] All edges and surfaces of the latch member 86 are rounded
and smooth especially those on that portion 108 of the latch member
facing outwardly of the recess 88. The only exception is the lip
100 which lies on that portion 109 of the latch member facing
inwardly of the tray 74, to thereby present no sharp edges or
surfaces which may engage and tear the users protective glove (not
shown). All portions of the latching mechanism 78 are integrally
molded with either the tray 74 or lid 76 thereby reducing
manufacturing and assembly costs. Of course, the orientation of the
latching mechanism 78 may be reversed, such that the latch member
86 is formed in the tray 74. Further, the lid 76 could be adapted
to pivot about a hinge (not shown) and of course, the latching
mechanism 78 need not be provided in the endwall 84 but could be
located elsewhere on the container 72. However, the orientation
illustrated in FIG. 5 is particularly convenient.
[0070] FIGS. 7 and 8 illustrate an alternative arrangement for a
tray 110 according to the invention. The tray 110 may be used with
a sterilization container as in the first and second embodiment and
differs primarily in its base 112. The base 112 comprises a flat
panel 114 having a plurality of apertures 116 therethrough.
Additionally, a number of larger, elongated apertures 118 penetrate
the panel 114 and an upwardly extending lip 120 encircles each of
the elongated apertures 118. The lips 120 support a mat 122 and
further provide rigidity to the tray base 112. Apertures 124
through the mat 122 aligned with the elongated apertures 118
through the tray base 112 to provide an efficient diffusion path
for sterilizing gases.
[0071] FIG. 9 illustrates a stacking device 124 for stacking
sterilization trays 10 during a sterilization procedure. The
stacking device 124 is rectangular in shape and of slightly larger
dimensions and than the sterilization tray 10 (not shown in FIG.
9). It comprises vertical sidewalls 126 and vertical endwalls 128.
An L-shaped shelf member 130 extends horizontally inwardly from
each corner 132 of the stacking device 124. As illustrated in FIGS.
9 and 10, each of the sidewalls 126 and endwalls 128 has elongated
openings 134 therethrough of similar vertical dimensions to the
shelf member 130 so that when containers 10 are stacked using the
stacking device 124, the flow of sterilizing gases into and out of
the individual containers 10 is not impeded by the stacking device
124.
[0072] FIG. 10 shows two sterilization containers 10, each wrapped
in a sterile wrap material 136. The stacking member 124 sits atop a
first tray 10 with the shelf member 130 resting upon the tray 10.
The second tray 10 rests upon the shelf member 130. Both trays 10
are positioned within the side and endwalls 126 and 128 of the
stacking device. Thus, the two trays 10 are stacked and separated
from each other with a full and open flow path thereabout.
[0073] FIG. 11 illustrates an alternative embodiment of a stacking
device 138. In place of the opening 134, each of the side and
endwalls 140 and 142 respectively have a low vertical profile
vertically offset from a shelf member 144 to thereby provide an
open flow path to the stacked trays (not shown in FIG. 11).
Vertical ribs 146 on the side and endwalls 140 and 142 provide
rigidity and maintain an open flow path, if the stacking device is
placed next to another stacking device or flat surface.
[0074] FIG. 12 illustrates an alternative embodiment of a lid 150
according to the invention. The lid 150 duplicates the lid 16 of
FIGS. 1 and 3, with several modifications. Accordingly, features
similar to those on the lid 16 will be designated with similar
numerals with the addition of a single prime symbol (').
Specifically, the lid 150 differs from the lid 16 in its mixture of
round and elongated apertures 152 and 154 respectively. Also, an
additional fillet 156 has been added at each corner which both
strengthens the lid 150 aids in lifting the lid 150 above the base
8 (not shown in FIG. 12) for improved circulation.
[0075] Liquid crystal polymers are known for their difficulty in
molding. One particular problem arises where opposing flows of
molten polymer meet. Such areas often have reduced strength and
accordingly it is desirable to locate them away from areas of the
molded article which will be subjected to high levels of stress. In
the lid 150, the recess 60' is formed by a core pin in the mold
(not shown). The molten polymer flows around the core pin and meets
to enclose the recess 60'. Normally these flows would meet at the
retaining lip 64'. However, this area is subjected to high
stresses. Accordingly, the lid 150 is formed with a pair of flow
leaders 158, each leading from a center area 160 of the lid 150
where the molten polymer is injected in the molding process and
leading to an inside corner 162 of the respective recesses 60'.
During the molding process the molten polymer thus flows around the
core pin and the opposing flows meet at a side portion 164 of the
recess 60'.
[0076] While the invention has been particularly described in
connection with specific embodiments thereof, it is to be
understood that this is by way of illustration and not of
limitation, and that the scope of the appended claims should be
construed as broadly as the prior art will permit.
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