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Патент USA US3081000

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March 12, 1963
M. c. PARKINSON ETAL
" 3,080,990
FREEZE-DRYING FLASKS
Filed March 10, 1961‘
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INVENTORS
MART/Al 6‘. PAIF/f/A/JOA ,
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ATTORNEY.
United States Patent 0 MIC€
3,080,990
Patented Mar. 12, 1963
1
2
3,080,990
contents. The elastomeric material is one which retains
its elasticity and thus insures a gas-tight seal at the tem
FREEZE-DRYING FLASKS
Martin C. Parkinson, Poughkeepsie, and Charles E.
Bender, New Paltz, N.Y., assignors to The Vir Tis Co.,
Inc., Gardiner, N.Y., a corporation of New York
Filed Mar. 10, 1961, Ser. No. 94,848
2 Claims. (Cl. 215—31)
peratures at which the vacuum drying is performed. Pref
erably, sealing member 20 is made of a silicone rubber
elastomer having a durometer of from‘ 40' to 80, and most
desirably a durometer of about 50. Such silicone rub—
bers are formed by milling methylpolysiloxanes with ap
propriate ?llers, such as silica, titania, zinc oxide or iron
oxide, and with a curing agent such as benzoyl peroxide,
This invention relates to sectional freeze-drying ?asks
utilized in the drying of biological materials, and more 10 2,4-dichloro benzoyl peroxide, or other organic peroxides.
particularly to such ?asks designed for use under high
The methylpolysiloxanes are prepared by hydrolyzing
vacuums, of the order of 1 micron.
‘
chlorosilanes such as methyl trichlorosilane, dimethyl di
In the preservation of biological substances for further
chlorosilane, or methylphenyl dichlorosilane, and bodying
use, it is necessary to uniformly dry the substances as com
the resin dispersions to produce the corresponding poly
pletely as possible without introducing changes in their 15 siloxanes. The silicone rubber sealing member, prefer
physical structure or alteration of the chemical reactivity
ably, is composed of a dimethylpolysiloxane containing
thereof. One of the most important methods for accom
composition, i.e. a dimethylpolysiloxane plus the usual
plishing such drying involves the utilization of freeze-dry
?ller. Such compositions vare vproduced by polymerizing
ing apparatus in which the material to be dried is frozen
dimethyl dichlorosilane. For example, the commercial
and maintained at very low temperatures, of the order of 20 product sold by Union Carbide Corporation under its trade
~80° C., and then subjected to regulated amounts of heat
designation KW-l3001 Silicone Rubber Masterbatch can
under high vacuums, in order to sublimate the ice present,
be used as the base. To this base is added known curing
while the frozen mass is maintained at temperatures well
agents, e.g. 2,4-dichloro benzoyl peroxide and a ?ller, and
below its freezing point.
the resultant mixture cured in a conventional manner to
Freeze-drying ?asks heretofore used have entailed the 25 produce the silicone sealing member.
bothersome manipulation of conventional ground glass
The elastomeric sealing member 20 consists‘ essentially
joints which must be carefully lubricated and ?tted to
of a cylindrical housing 21 having a thin inner ?ange 22
gether in the assembly of the freeze-drying apparatus.
approximately midway between the end faces 23‘ and 24 of
Joints of vglass against glass are objectionable not only
the housing. The inner ?ange 22 has an internal diam
because of the expense involved in making a gas-tight 30 eter approximately equal to the internal diameters of the
ground glass joint but also because they tend to fail under
rims 13 and 15 of the lower and upper ?ask sections, re
high vacuum.
'
spectively, and includes opposed faces 25 and 26 for seat
It‘is among the objects of this invention to provide a
ing the respective rims thereon. The sealing member ad
freeze-drying ?ask which is simply constructed, easily
ditionally includes an outer ?ange 27 positioned approx~
handled and evacuated with a minimum of manipulative 35 imately midway between the ends 231 and 24 of the housing
effort, and does not involve a glass to glass joint.
~ Other objects and advantages of the present invention
will be apparent from the following detailed description
21. The outer ?ange 27 has a substantially greater thick
ness than the inner ?ange 22, and is positioned directly
opposite the inner ?ange symmetrically thereof in order to
reinforce‘ the side walls of the housing 21 in the regions
In the accompanying drawing forming a part of this 40 adjacent the inner ?ange 22. Desirably, the side walls of
speci?cation and showing, for purposes of exempli?cation,
the housing 21 have a length of from % to 1% inches
a preferred form of this invention, without limiting the
between the end faces 23 and 24, the inner ?ange 22 has a
claimed invention to such illustrative form:
thickness of from 1/32 to 3/432 ‘inch between its opposed
thereof.
_
.
.
FIGURE 1 is a perspective view of a freeze-drying
faces 25 and 26 and the outer ?ange 27 has a thickness
?ask according to the invention, with the parts shown in 45 of from 3,5,2 to %6 inch, measured along the length of
disassembled positions;
the side walls of the housing. These dimensions insure
FIGURE 2 is a vertical section through the sealing
member joining the ?ask sections of FIGURE 1; and
FIGURE 3 is a partially cut-away vertical section
the maintenance of a secure gas-tight seal between the
?ask sections 10 and 11, as pointed out below.
As shown in FIGURE 3, the rims of the ?ask sections
through the joint produced between the assembled ?ask 50 10 and 11 engage the opposed faces 25 and 26 of the inner
sections and the sealing member.
In FIGURE 1, a pair of ?ask sections 10 and 11 are
shown, each of which is desirably formed of a temperature
stable glass or plastic material. The lower ?ask section
?ange 22 of the sealing member 20* with the bevelled outer
lips 14 and 16 pressing against the inner ?ange and the
adjacent side walls of the housing 21. The pressure of
the‘ rim lips on the sealing member compresses the elas
10, which is generally cylindrical in shape, is permanently 55 tomeric material thereof and forms annular indentations
closed at one end 12 and is provided vwith a circular rim 13
28 and 29 in the housing 21 of the sealing member in
at the opposite end, the rim having a smoothly bevelled
which indentations the rims 13 and 15 are seated, thus
outer periphery or lip 14.
V
forming a gas-tight seal. The outer ?ange 27 serves to
The upper ?ask section 11, which is generally hemi
prevent bulging or rupturing of the sealing member by
spherical in shape, has at its base, a circular rim 15 of the 60 the compressive forces created by the seated rims and
same circumference as the rim 13', which rim 15 is pro
vided with a smoothly bevelled outer periphery or lip 16.
At the pole end of the hemispherical upper ?ask section
additionally facilitates application of the sealing member
to the ?ask sections and removal therefrom.
Upon exhaustion of the air through the tubular outlet
11 a tubular outlet 17 is located for connection to a vacu
17 in the upper ?ask section 11, the assembled ?ask sec
um pump or other suitable vacuum source. A number 65 tions become even more tightly sealed together, and vac
of rings 18v are provided on the tubular outlet 17 insur
ing a tight engagement with a suitable connector leading
uums of the order of 1 micron or lower may be safely
produced therein. It is believed that the inner ?ange 22
and the side walls of the cylindrical housing 21 composed
The upper and lower ?ask sections are joined by a seal
of the elasto-mer having a durometer of from 40‘ to 80
ing member 20' composed of an elastomeric material which 70 actually ?ow over the edges of the rims 13 and 15 of
is resistant to the low temperatures, of the order of —80°
the ?ask sections as the vacuum is applied, and thereby
C., produced upon evacuating the ?ask and freezing its
provide an extremely tight seal between thte parts of the
to the source of the vacuum.
3,080,990
3
freeze-drying ?ask. It will be understood that the above
explanation is intended as illustrative and not limiting of
the mode of operation of the freeze-drying ?ask of this in
vention.
Thus, the present invention provides a freeze-drying
?ask which is simply constructed, easily handled, and
evacuated with a minimum of manipulative effort to ob
4
below therewithin comprising, in combination, a pair of
?ask sections each having a rim at one end thereof pro
vided with a smoothly bevelled outer lip for sealing, one of
said ?ask sections having the opposite end permanently
closed, and the other of said ?ask sections being of gen
erally hemispherical shape and having a tubular outlet for
connection to a source of vacuum, and a silicone rubber
sealing member having a durometer of 50, said sealing
member consisting essentially of a cylindrical housing in
Since different embodiments of the invention may be
made without departing from the scope thereof, it is 10 cluding side walls having a length of from % to 11/2
inches and provided with a thin inner ?ange having a
intended that all matter contained in the above descrip
thickness of from 1/32 to 5732 inches and an outer ?ange
tion or shown in the accompanying drawing shall be inter
having a thickness of from %2 to (716 inches positioned
preted as illustrative and not in a limiting sense.
symmetrically of said inner ?ange and approximately
What is claimed is:
1. A freeze-drying ?ask for maintaining vacuums of 15 midway between the ends of said side walls of said hous
ing, said rims of said ?ask sections engaging opposed
one micron and below at temperatures of —70° C. and
faces of said inner ?ange with said bevelled outer lips
below therewithin comprising, in combination, a pair of
of said rims pressing against said inner ?ange and the
?ask sections each having a rim at one end thereof pro
adjacent side walls of said housing, thereby compressing
vided with a smoothly bevelled outer lip for sealing, one
the silicone rubber and forming an annular indentation
20
of said ?ask sections having the opposite end permanently
in said housing in which said rims seat to provide a gas
closed, and the other of said ?ask sections being of gen
tight seal between said ?ask sections, said outer ?ange
erally hemispherical shape and having a tubular outlet
of said sealing member reinforcing the side walls of said
for connection to a source of vacuum, and a silicone
housing in the region of compression of the silicone rub
rubber sealing member having a durometer of from 40 to
80, said sealing member consisting essentially of a cylin 25 her to prevent rupture thereof and to facilitate applica
tion of said sealing member to said ?ask sections and re
drical housing having a thin inner ?ange extending ap
moval therefrom.
proximately midway between the ends of the side walls of
said housing and an outer ?ange directly opposite the
References Cited in the ?le of this patent
inner ?ange having a substantially greater thickness than
UNITED STATES PATENTS
said inner ?ange, said rims of said ?ask sections engaging 30
tain vacuums of the order of 1 micron.
opposed faces of said inner ?ange with said bevelled outer
lips of said rims pressing against said inner ?ange and the
adjacent side walls of said housing, thereby compressing
the silicone rubber and forming an annular indentation
in said housing in which said rims seat to provide a gas
tight seal between said ?ask sections, said outer ?ange of
1,463,360
1,937,877
2,210,183
2,538,684
2,709,534
2,763,609
Foote _______________ __ July 31,
Edwards ______________ __ Dec. 5,
Schweighart ___________ __ Aug. 6,
Gushard et a1 _________ __ Jan. 16,
Johnson et al. ________ __ May 31,
1923
1933
1940
1951
1955
Lewis et a1 ____________ __ Sept. 18, 1956
2,778,173
Taunton ______________ __ Jan. 22, 1957
said sealing member reinforcing the side walls of said hous
2,942,390
Lerner ______________ __ June 28, 1960
ing in the region of compression of the silicone rubber to
prevent rupture thereof and to facilitate application of
OTHER REFERENCES
said sealing member to said ?ask sections and removal 40
Uses
and
Processing
of Silicone Rubber, article in Mod
therefrom.
ern Plastics, pages 1012, 103 and 104 of December 1946.
2. A freeze-drying ?ask for maintaining vacuums of
This article can be found in Division 15, class18~55F.
one micron and below at temperatures of —70° C. and
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