Note: Descriptions are shown in the official language in which they were submitted.
CONNECTION OF POLYVINYL CHLORIDE TO
ESSENTIALLY POLYOLEFIN MATERIALS
Technical Field and Description o~ Prior ~rt
In the copending U.S. Patent Application Serial No~
5 067,Q68r filed Augus~ 15, 1979, now U.S. Patent No.
4,327,726, by Peter C. Kwong and Dean G. Laurin, a
connector member for dissimilar materials is disclosed.
Specifically, the connector member is made out of a
plast~ ul~ion which is adherent both to polyvinyl
10 chloride and to cer~ain materials which are substantially
of polyolefin nature. The connector may be heat sealed to
the polyolefin-type material, while it is solvent-bonded
to the polyvinyl chloride. Thus, for example, a blood bag
made of a modified polyolefin-type material containing
15 polypropylene~ a block copolymer of polystyrene blocks and
rubber polyolefin blocks, and poly(ethylene-vinyl acetate)
may be bonded through such a connector to a polyvinyl
chloride donor tube, where normally there is virtually no
adhesion at all between those two materials.
Specifically, the material of the connector of the
above-cited application i8 a mixture which comprises 65
percent o~ a blend of 20 parts by weight of a
polypropylene-based material, 60 parts by weight of a
polystyrene-poly(ethylene butylene) block copolymer, and
25 20 parts by weight of poly(ethylene-vinyl acetate); and 35
percent of a polyes~er type block copolymer.
However, while ~uch a material is solvent-bondable to
polyvinyl chloride, it is not as strongly adherent to the
polyvinyl chloride as might be desired in numerous circum-
30 stances, since the bonded joint between the two materialscan be separated with a relatively low force.
In Hoh et al. U.S. Patent No. 3,832,314 a segmented
copolyester adhesive and coating composition is disclosed
%~
in ~hich a thermoplastic, segmented copolyester elastomer
is mixed with a low molecular weight thermoplastic resin
such as a styrene polymer, a chlorinated aliphatic hydro
carbon wax or the like. Such a structure, however, is not
5 contemplated for the use of this invention, and does not
include polystyrene-rubbery olefin block copolymer contem-
plated for use in this invention.
In accordance with this invention, an improvement in
the formulation disclosed in the above-cited patent appli-
10 cation is provided, resulting in a plastic composition anda connector member made of such composition which is
capable of simultaneous, stronger sealing to both poly-
vinyl chloride plastics and essentially polyolefin
plastics ranging from polypropylene to the modified
15 polyolefin plastic formulation described above containing
the polypropylene, the polystyrene-rubbery polyolefin
block copolymer, and the poly(ethylene-vinyl acetate).
Description of the Invention f
~, In accordance with~th~l~s invention, a plastic composi-
20 tion i8 ~rovided which is capable of simultaneously seal-
ing to both polyvinyl chloride plastics and essentially
polyolefin plastics. The formulation comprises:
(a) from 1 to 8 percent by weight of a polyolefin
consisting essentially of propylene units;
(b) from ~0 to 65 percent by weight of a block
copolymer, having thermoplastic rubber characteristics,
consisting essentially of blocks, preferably comprising 50
to 85 percent by weight of the polymer molecule, of a rub-
bery olefin polymer, and blocks of polystyrene;
(c) from 35 to 55 percent by weight of a ~lexible
block copolymer of covalently-bonded polybutylene tere-
phthalate units and poly(l,~-butylene oxide) units; and
(d) from 0 to 15 percent by weight of a poly(ethy-
lene-vinyl acetate) softening agent containing preferably
no more than 35 percent by weight of vinyl acetate units.
The plastic composition o~ this invention can be heat
sealed to polypropylene, polyethylene, and other true
polyolefin materials. Also, it can be heat-sealed to
modified polyolefin-type blends for making flexible,
collapsible containers and other items as described above
and as disclosed in U.S. Patent ~o. 4,140,162.
~n the o~hsr hand, as stated above, the connector and
formulation ~f this invention adheres very well, by
solvent sealing using methylisobutylketone or acetone for
example, to polyvinyl chloride formulations so that the
polyvinyl chloride component of a device, for example
donor tubing, may be reliably and firmly sealed to a blood
bag made of one of the above described polyolefin-type
formulations. In the absence of the connector of this
invention, polyvinyl chloride simply does not seal at all
to most substantially polyolefin formulations.
The term "polyolefin" as used herein is intended to
denote halogen-free materials which are polymerized by the
basic vinylic polymerization reaction of ethylene or a
substituted ethylene. It is con-templated that certain
amounts of substituted ethylene materials may be present,
such as styrene, acrylonitrile vinyl acetate, and the
like, which cause the material to be not true poly-
olefins. These are still contemplated to be within the
scope of this invention as essentially polyolefin
materials, since their polymerization still approximates
the vinylic polymerization reaction of ethylene, and
related olefins such as propylene and butadiene.
Basically, the formulation of this invention differs
from the formulation of the previously cited patent appli-
cation in that the polypropylene ingredient (a) is reduced
~ 42~i~
in quantityi Surprisingly, this turns out to greatly
improve the capability of the formulation to be solvent
bonded to polyvinyl chloride, while still providing
excellent heat seal adhesion to many polyolefin-type
5 formulations such as those described above. However, the
presence of at least l percent and preferably 1.5 to 6
percent of polypropylene, or a material consisting essen-
tiall~ ~f polypropylene units with only minor amounts of
added ~nits such as ethylene, is desirable for improved
lO heat sealing to many of the polyolefin-type materials.
Ingredient (b), the block copolymer of styrene and the
rubbery olefin, preferably is a block copolymer of poly-
styrene with poly(ethylene-butylene), with the ethylene
and butylene being in approximately equal quantities.
15 Such materials are sold by the Shell Chemical Company
under trademark Kraton G. Alternatively, similar
materials sold by the Shell Chemical Company include block
copolymers of styrene and polybutadiene.
Ingredient (c) of the plastic composition of this
20 invention may be a flexible block copolymer of covalently
bonded polybutylene terephthalate and poly(l,4-butylene)
oxide units. Preferably the butylene oxide (polyether)
blocks comprise from 50 to 70 percent by weight of the
flexible block copolymer composition, for example 60 per-
25 cent. A type of block copolymer is available from E. I.DuPont deNemours & Company under the trade n ~ HYTREL.
The specific material sold under the trade~ ~ e HYTREL
4056 is preferred for use herein. Preferably, the
flexible block copolymer of ingredient (c) may exhibit a
30 melt flow rate of no less than 15 and typically 18 grams
per lO minutes at 220 C. as described in the test of ASTM
Dl238. Of course, the material of ingredient (c) should
have sufficient molecular weight to be a solid thermo-
plastic material of satisfactory structural integrity.
,
~? ,.1! a~ ~9 ~9 A ~
Ingredient (d), the poly(ethylene-vinyl acetate), may
also be added as desired to lubricate the flow o~ the
material of the connector of this invention during heat
seal. Also, it may be a lower cost material than ingre-
5 dient (c), which it may partially, but not completely,replace in accordance with this invention.
Frequently, the blended material made from ingredients
(a) ~hF~U~h ~d) is white, rather than being translucent or
transparent, implying a certain amount of phase incompa-
10 tibility. Nevertheless, highly satisfactory connectorparts may be made from the material, and its tensile and
other physical properties and softening temperature may be
sufficient for autoclaving and other normal handling of
disposable medical devices with which it may be used.
Pellets of the ingredients of the plastic composition
of this invention may be ~imply mixed together in their
pr~per ratio and poured into an injection molding
machine. The molding screw takes care of the final mixing
in the melted state, so that the formulation of the
20 material can take place simultaneously with the molding
process.
The polyolefin ingredient (a) is substantially poly-
propylene, but may contain for example from 2 to 5 percent
by weight of ethylene units or the like. A small amount
25 of at least about 1.5 percent by weight of the polyolefin
ingredient (a) is preferred to improve the heat sealing
characteristics of the material, while the solvent bonding
capability of the formulation to polyvinyl chloride begins
to be reduced at concentrations of ingre!dient (a) above 6
30 percent, although it remains improved up through at least
about 8 percent by weight of ingredient (a).
EXAMPLE I
A formulation of this invention was mixed in an injec-
tion molding machine, containing ~a) 2 percent by weight
2~
of polypro,pylene having a minor amount of ethylene units;
(b) 50 percent by weight of Kraton G 1660 poly(styrene-
ethylene butylene) block copolymer; (c) 38 percent of
HY~REL 4056 polyester block copolymer; and (d) 10 percent
5 by weig~!t of poly(ethylene-vinyl acetate) containing about
28 percent of vinyl acetate units, Such a blended
material may be extruded into strips, or formed into a
connector in accordance with this invention.
As a specific demonstration of its bonding strength to
10 polyvinyl chloride, thin strips of the above formulation
were solvent-bonded with cyclohexanone to a strip of a
polyvinyl chloride formulation plasticized ~ith di-2-
ethylhexylphthalate. The surfaces of both strips were
wetted by cyclohexanone. The wetted sides were joined
15 together and held under pressure overnight for drying~
For testing, an unbonded end of each of the sample
strips were clamped to the jaws of an Instron testing
machine. The cross head speed of the test was 10 inches
per minute; the chart speed 10 inches per minute; and the
20 full scale was 10 pounds. The force required to tear the
two strips apart was 5.97 pounds per inch.
This exceeds by about 40-fold the comparable results
obtained when the specifically-disclosed formulation of
the previously cited patent application is similarly
25 tested, that material requiring approximately 0.14 poun~
per inch for separation from the same type of polyvinyl
chloride strip.
EXAMPLE II
The following formulation was blended into a homo
30 geneous material: (a) 5 percent by weight of the same
polypropylene formulation as in Example I; (b) 45 percent
by weight of the poly(styrene-ethylene butylene) block
copolymer of Example I; and (c) 50 percent by weight of
the polyester type block copolymer of Example I. This
formulation was formed into strips and tested by bonding
to the same polyvinyl chloride formulation as in Example
I. 5.05 pounds per inch were required to pull the two
strips apart.
In the drawing, Figure 1 is a fragmentary, elevation
view, taken partly in vertical section, of a blood bag of
a gen~r~lly known design, made of an essentially poly-
olefin blend, carrying the connector of this invention,
which, in turn, is ~onnected to donor tubing made of a
10 polyvinyl chloride formulation.
~ eferring to the drawing, blood bag 10 is shown, which
may be of conventional design. Blood bag 10 may be made
of a polyolefin blend which may include 20 parts by weight
of a polypropylene polymer having a melt flow of about 2,
15 with a small amount of copolymerized ethylene; 60 parts by
weight of a block copolymer having thsrmoplastic rubber
ch~racteristics, consisting of a central block of
poly(ethylene-butylene) and terminal blocks of poly-
styrene; and 20 parts by weight of a poly(ethylene-vinyl
20 acetate) copolymer.
Blood bag 10 as shown defines an access port 12 which
in turn defines a terminal flange 14 whic~ is integrally
formed in relatively thick section along with the thinner
sections of the flexible walls of blood bag 10. Web 16 as
25 shown communicates between port 12 of ~he blood bag and an
adjacent port (not shown). In accordance with ~his
invention, connector member 18 is disc]osed, being prefer-
ably an injection molded, single piece of the formula of
this invention, comprising a tubular portion 20 and
30 terminating in a flange 22. Connector member 18 may be of
the formulation de~cribed in Example I above.
Flange 22 of connector 18 may be conventionally heat
sealed to flange 14 of the blood bag, using for example an
ultrasonic sealing device or a spin welding device, so
that a common ~ore 24 passes between connector 18 and port
12 of the blood bag.
Additionally, polyvinyl chloride donor tubing 26 may
be solvent-sealed to the exterior of tubular portion 20 of
5 connector 18, using, for example, cyclohexanone or any
other appropriate volatile solvent for both of the
materials. Both flange 14 and tubing 26 adhere strongly
to connector 18 with the result that great simplification
of the bond between these dissimilar materials may be
10 obtained.
The above has been offered for illustrative purposes
only, and is not intended to limit the invention of this
application, which is as defined in the claims below.
