Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
- 2 - HOE 77/F 214 K
The present invention relates to a thermoplastic compo-
sition for the manufacture of medical apparatuses and
instruments.
It is known to use receptacles made from pasticizer-
containing polyvinyl chloride for collecting, treating andadministering parenteral liquids, for example blood, blood
substitutes, infusion solutions and other physiological
liquids. This application requires, on the one hand, a high
strength of the receptacle and, on the other hand, good
flexural properties, a sterilization resistance and a good
weldability and furthermore a high transparency in order to
enable an observation of a possible agglutination of the
blood. These PVC mixtures have the disadvantage that the
plasticizer contained therein may migrate or be extracted.
German Auslegeschrift 2,502,182 points to this fact. Plasti-
cizer-containing poly~inyl chloride has the further disad-
vantage that it has a relatively high water vapor permeabi-
.~ lity, which after extended storage of aqueous liquids in
receptacles made therefrom leads to evaporation losses.
Therefore, plastics containers must be enclosed additional-
; ly in metal containers.
Polyvinyl chloride mixtures which contain so-called
polymer plasticizers show a less pronounced migration and a
lower extractibility of the plasticizers. However, a pH
shifting occurs in the course of the water vapor steriliza-
tion in an autoclave at a temperature of 120C, due to a
limited hydrolyzability of the polymer plasticizers and, as
a consequence of the extraction of oxidizable substances,
29 an increase of the permanganate indices in the aqueous
: .
. ~
- 3 - HOE 77/F 214 K
extract. For this reason, the aforesaid German Auslege-
schrift 2,503,182 proposes the use of a definite polyure-
thane Or high purity as plasticizer for PVC.
A very high purity, however, involves procedures which
render the mixtures according to the aforesaid German
Auslegeschrift expensive and on the other hand, the water
vapor permeability of these mixtures, too, is above the
desired value.
The present invention, consequently, was confronted
with the problem of providing a thermoplastic composition
for the manufacture of medical apparatuses and instruments,
which should not have the aforesaid disadvantages, that is
to say, which contains no extractible or hydrolyzable
components while having a low water vapor permeability, a
high transparency and strength and a good weldability.
This problem is solved by using for the manufacture of
medical apparatuses and instruments coming into contact
with parenteral liquids, for example blood, blood substitu-
tes, infusion solutions and other physiological liquids a
thermoplastic composition consisting of a definite mixture
of a special chlorinated polyolefin and polymers of acrylic
and/or methacrylic acid esters.
The present invention, consequently, relates to a ther-
moplastic composition for the manufacture of medical appara-
tuses and instruments which come into contact with paren-
teral liquids, characterized by consisting of from 50 to
99.5, preferably of from 70 to 98, parts by weight of chlo-
rinated polyolefin having a chlorine content of from 15 to
29 45, preferably of from 25 to 40 % by weight and an average
C~
- 4 - HOE 77/F 214 K
molecular weight of from 30,000 to 300,000, preferably of
from 40,000 to 100,000 (calculated from the chlorine content
and from the molecular weight of the starting polyethylene,
determined by gel chromatography; cf. WeRlau, Makromoleku-
lare Chemie, 26, (1958), pages 96 - 101) and of from 0.5 to
50, preferably of from 2 to 30, parts by weight of polymers
of acrylic and/or methacrylic acid esters.
The present invention moreover relates to a method of
using this thermoplastic composition for the manufacture of
corresponding medical apparatuses and to these medical
apparatuses.
Suitable chlorinated polyolefins are chlorination pro-
ducts of polyolefins especially polyethylene, polypropylene
and copolymers of ethylene and propylene, especially low
~- 15 pressure polyethylene and copolymers of ethylene having low
portions of, for example, from 1 to 5 mol % of propene,
butene-1 or hexene-1.
The polyolefins used for the chlorination advantageous-
ly have a reduced specific viscosity (RSV)-determined with
a 0.1 ~ solution in decahydronaphthalene, at 135C, accord-
ing to ISO/R 1191 - of from 1 to 10, preferably of from 1.2
to 5 dl/g. When using polyolefins of higher RSV value
(higher molecular weight) for the chlorination, there
are obtained thermoplastic compositions which are difficult
to process, whereas polyolefins of lower RSV values yield
compositions which have rather bad mechanical properties.
Since the water vapor permeability of the compositions
is influenced by the crystallinity of the chlorinated
29 polyolefins, there are used preferably chlorinated polyole-
,~ . .
~4~
- 5 - HOE 77/F 214 K
fins which have a residual crystal content of from 1 to 20,
preferably o~ from 5 to 15, % determined by differential
thermoanalysis.
The polyolefins are preferably chlorinated in aqueous
suspension, for example according to the process of German
Auslegeschrift 1,420,415.
The thermoplastic composition to be used according to
the present invention may be prepared by mixing both poly-
mers, preferably according to the melt mixing process.
The transparency of mixtures of this type may be improved
by using a poiymer of acrylic and/or methacrylic acid
ester, whose refractive index is substantially adapted to
that of the chloroolefin, for example by using a copolymer
of two adequate acrylates or methacrylates.
A better homogenization and, consequently, a better
transparency is obtained when polymerizing the acrylic
and/or methacrylic acid esters in the presence of the
chlorinated polyolefin. For this reason, preference is
given to the use of one of the thermoplastic compositions
prepared according to the present invention.
The acrylic and/or methacrylic acid esters are poly-
;; merized in the presence of the chlorinated polyolefins,
preferably in aqueous suspension, for example, in the
folowing manner: The chloroolefin is suspended in water in
the presence of conventional suspension auxiliaries, forexample partially saponified polyvinyl acetate, alkyl
celluloses, for example methyl cellulose, hydroxyalkyl
celluloses, for example hydroxypropyl cellulose, alkoxyal-
29 kyl-celluloses, for example methyl-oxyethyl cellulose,
, ' . "', "~ ' '' ' . '
- ' ' " '
`~
. ~
- 6 - HOE 77/F 214 K
or gelatin, the monomer(s) is (are) added thereto and the
batch is stirred at room temperature or at slightly elevated
temperature in order to swell the chloroolefin in the
monomer or monomer mixture. Thereafter the free radical-
forming agent and optionally a molecular weight regulatorare added and the batch is heated to the polymerization
temperature, which generally is in the range of from 30 to
120C, preferably of from 40 to 100C. Alternatively,
the chloropolyolefin may first be swelled in the monomer or
monomer mixture and/or be dissolved therein, the resulting
dispersion or solution may be dispersed in water while
adding the suspension agent while the rest of the procedure
is as described above.
Suitable free radical-forming agents are conventional
compounds for this purpose, for example peroxides such as
benzoylperoxide, lauroylperoxide, peresters such as tertiary
butylperoxybenzoate or tertiary butylperpivalate, percar-
bonates, for example isopropylperoxydicarbonate, azo com-
pounds, for example azobisisobutyronitrile and the like
or corresponding mixtures. The quantity of the initiator
is generally in the range of from about 0.1 to 3 weight
- percent calculated on the monomers. It naturally depends
on the efficiency of the initiator, on the polymerization
temperature etc.
Suitable molecular weight regulators include, for
example, long chain mercaptans, for example dodecylmercap-
tan, dimerized C~methylstyrene, halogenated hydrocarbons,
aldehydes, ketones etc.
29 On principle, the above polymerization, which results
~_. .
': ' - - " '
.
.
- 7 - HOE 77/F 214 K
to a certain extent in a grafting of the monomer(s) onto
the chlorinated polyolefin so that the chloroolefin, the
polymer of acrylic and/or methacrylic acid esters and graft
polymers of these esters onto the chloropolyolefin can be
found at the same time, may alternatively be performed in
solution or as bulk polymerization, this procedure, however,
generally being not really advantageous in the present
case.
In dependence on the intended use, the properties of
the thermoplastic composition according to the invention
may be optimized by varying the content of polymeric acrylic
and/or methacrylic acid esters within the claimed range.
An increase of the chloropolyolefin content results in a
better elasticity, whereas the stiffness (hardness) and
transparency are improved when the content of polyacrylic
and/or methacrylic ac d esters is increased.
Suitable acrylic or methacrylic acid esters are espe-
cially those in which the alcohol component has of from 1
to 6 carbon atoms, since the polymers of these compounds
are compatible with the chloropolyolefins and do not lead
to turbidity. The alcohol component may be substituted by
hydroxyl groups or by the furan group. Individual esters
may be polymerized as well as mictures of several esters.
Examples of esters capable of being polymerized individual-
ly or in the presence of chloropolyolefins are: methylmeth-
acrylate, hydroxyethylmethacrylate, hydroxypropylmethacry-
late9 furfurylmethacrylate, ethylacrylate, isopropylacry-
late and butylacrylate.
29 Optionally the acrylic and/or methacrylic acid esters
:' ' .' :-
- ' . ' , ' " ' ' :
... . ..
- 8 - HOE 77/F 214 K
used accordinK to the present invention may contain small
amounts of further monomers, provided that the properties
of the plastic composition aimed at by the present inven-
tion, especially the low water vapor permeability and the
high transparency are not substantially impaired. Examples
of these monomers are: acrylonitrile, methacrylonitrile,
methacrylamide, vinyl esters, especially of saturated
carboxylic acids having from 2 to 12 carbon atoms, for
example vinyl acetate and vinyl propionate; furthermore
N-vinyllactams such as N-vinylpyrrolidone; copolymerizable
unsaturated hydrocarbons such as ethylene, propylene or
styrene and the like. Small amounts are those in the range
up to 10 weight percent, preferably up to 5 weight percent,
although some monomers may contain greater amounts without
being liable to a modification of their properties, which
can be determined by simple tests.
The term "acrylic and/or methacrylic acid esters" may
include in this context mixtures of the above esters with
- monomers of the above kind.
The thermoplastic compositions prepared according to
the present invention may be used for the production of a
great variety of medical apparatuses and instruments and
parts thereof, which come into direct or indirect contact
with parenteral liquids, for example blood bags, fexible
containers for infusion solutions, infusion tubes, suction
tubes and catheters. By parenteral liquids there are to
be understood blood as well as blood serum or any injec-
table solution for medical purposes such as solutions of
29 blood substitutes etc.
,
~''' ' - :
- 9 - HOE 77/F 214 K
A prerequisite for a high stability to storage of medi-
cal containers is that only a neglectible gas exchange
between the closed container and the exterior such as an
evaporation of the liquid present in the container or an
oxygen absorption from the exterior or no exchange at all
occurs. Furthermore, microorganisms which decompose the
parenteral liquid should not penetrate into the container.
The thermoplastic composition according to the invention
fulfills the above requirements and in addition thereto,
the water vapor permeability is substantially lower than
that of plasticizer-containing polyvinyl chloride. It is,
however, sufficiently high to prevent a turbidity during
the sterilization with water vapor, which would fade very
slowly, partially only after several days. The water vapor
permeability may be easily optimized by the selection of
- the monomeric esters. It is increased when methylmethacry-
late is partially replaced by hydroxypropylmethacrylate,
for example.
The plastic- composition according to the present inven-
tion may be molded in conventional processing machines suchas extruders or calenders to have the desired shape. In
order to prevent a decomposition during processing, stabi-
lizers must be added. For this purpose only physiological-
; ly acceptable stabilizers, for example fatty acid salts of
-~ 25 calcium, magnesium, aluminum and zinc, organic phosphites,
aliphatic epoxides, polyhydric alcohols and phenolic anti-
oxidants, should be used. A stabilizer combination consist-
- ing of from 1 to 3 weight percent of calcium-aluminum steara- -.
.
. . .
-:................. -
~: -
.
L4~
- 10 - HOE 77~F 214 K
te, 0.5 to 1 weight percent Or a secondary or tertiary or-
ganic phosphite, 1 to 3 weight percent of an aliphatic ep-
oxide and 0.05 to 10 weight percent Or a phenolic antioxy-
dant, calculated on the thermoplastic composition, has proved
advantageous. Furthermore, conventional light stabilizers,
lubricants, pigments and fillers, for example barium sulfate
as contrast medium for radiographic purposed, may be used.
The additives may be added during the preparation of the
thermoplastic composition or subsequently.
10In most cases, the mechanical strength of the shaped
articles prepared from the compositions according to the
present invention is sufficiently high for the intended
use. In some cases, however, it may be advantageous to
improve the mechanical strength by incorporating supporting
tissus made from inorganic or organic material, such as
; glass fibers or plastics fibers, for example of polyester
or polyamide. For this purpose sandwich sheets may be used
alternatively, the inner sheet of which coming into contact
with the parenteral liquids, consists of the molding compo-
- 20 sitions according to the invention (and acts as a lining)
and the outer sheet of which is composed of a material
which should have a great mechanical strength and be also as
transparent as possible. The water vapor permeability of
the outer supporting sheet may be relatively high, since
the inner sheet is little permeable.
The ~ollowing examples illustrate the invention:
E X A M P L E 1:
81 Parts by weight of a fine grained chlorinated
- 29 polyethylene having a chlorine content of 40 weight percent
' .
:, -
, .
- 11 - HOE 77/F 214 K
and a residual crystallinity of 4 percent (determined by
differential thermoanalysis) which ha~ been obtained by
chlorinating a low pressure polyethylene having a RSV value
of 2.3 dltg (measured in a 0.1 % solution in decahydronaph-
thalene at 135C) are suspended with 160 parts of waterand 0.2 part Or a partially saponified polyvinyl acetate
(viscosity 2 cP in 2 ~ aqueous solution, acetyl content
42 %) in a stainless steel vessel having a content of 40 li-
ters by means of an anchor agitator. 19 Parts by weight
of methylmethacrylate are introduced under pressure with
the exclusion of oxygen and while stirring at room tempera-
ture the chlorinated polyethylene is swollen in the monomer.
Thereafter 0.06 part by weight of tertiary butylperpiva-
late is added and polymerization is initiated by heating
the contents of the vessel to 90C. After 2 hours the
resulting mixture is allowed to cool and the fine grained
product is withdrawn, washed and dried. The yield, calcu-
lated on the feed monomer, is 99.9 %.
The product is stabilized with 1 weight percent of
Ca/Al stearate, 0.5 weight percent of trisnonylphenylphos-
phite, 3 weight percent of epoxidized soybean oil and 0.1
weight percent of tetrakis-/ methylene-3-(3',5'-di-tertiary
butyl-4'-hydroxyphenyl) propionate 7 methane (IrganoxR .
1010).
The obtained polymer is rolled on mixing rolls at 175C
to form a rough sheet and the letter is squeezed into sheets
of a thickness of 400 /um. The clearness of the sheet ob-
tained (dispersion 21 percent) is substantially better than
29 that of a corresponding sheet prepared from the feed chlo-
.,
.~., .,;, . . .
- - , ~ '
- 12 - HOE 77/F 214 K
ropolyethylene (dispersion 55 ~).
The sheets are sterilized in an autoclave at 120C
and the aqueous extract is examined according to DIN (German
industrial standard) 58 361/4 (blood bag examination).
Table 1 shows the result obtained, compared with a
sheet made from soft PVC of the state of the art (70 % of
PVC and 30 % of dioctylphthalate).
It can be seen from the ta~le that the values obtain-
ed in all of the examinati~ns are below the tolerable
limits and that a part thereof is even better than that of
soft PVC.
- 13 - HOE 77/F 214 K
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- 15 - HOE 77/F 214 K
The Examp1es 2 to 16 demonstrate further propertie~ of
the thermoplastic compositions according to the present
invention, which are of decisive importance for their use
for medical apparatuses and instruments which come into
contact with parenteral liquids.
E X A M P L E S 2 and 3: -
Example 1 is repeated, except that a chlorinated poly-
ethylene having a chlorine content of 34 weight % and a
residual crystallinity of 10 % is used, which has been
prepared by chlorinating a low pressure polyethylene having
a RSV value of 1.5 dl/g, by employing varying quantities of
methylmethacrylate (MMA). Calendered sheets of 400 /um
thickness are prepared from the polymer obtained for exami- .
nating the tensile strength and the elongation at break and
15 molded plates for determining the ball indentation hardness. ~-
It can be seen from table 2, that the hardness of the
thermoplastic composition depends on the content of methyl-
methacrylate.
Table 2
Example Ball indentation Elongation Tensile
hardness at breakstrength
N/mm2 % N/mm2
;
2: 85 % CPE/15 % MMA 16 742 10.9
3: 80 % CPE/20 ~ MMA 32 534 12.7
.
E X A M P L E S 4 and 5:
29Examples 2 and 3 are repeated by using instead of me-
.
"''"'' '`' ~ '' ' -
:::
. .
- 16 - HOE 77/F 214 K
thylmethacrylate hydroxypropylmethacrylate (HPMA). Table 3
shows the water vapor permeability of sheets of 400 /um
thickness prepared from various samples in comparison to
that of a sheet made from soft PVC. The water vapor
permeability is increased by incorporating hydroxy groups.
Consequently, it may be adjusted to the desired value.
Table 3
10 Example Water vapor permeability
g/m2 . 24 h
2: 80 % CPE/20 % MMA 0.33
4: 85 ~ CPE/15 g HPMA 1.42
15 5: 80 ~ CPE/20 % HPMA 2.03
COmDariSOn: 70 % PVC/30 % DOP 2.52
. _ _ _ _
.
; E X A M P L E S 6 to 8:
According to Example 1, varying quantities of methyl-
methacrylate (MMA) are polymerized in the presence of a
chlorinated polyethylene (CPE) having a chlorine content of
38 weight %, which has been obtained by chlorinating a low
pressure polyethylene having a RSV value of 1.5 dl/g.
Calendered sheets of 400 /um thickness are prepared
from the resulting product and from the feed chloropolye-
thylene and their transparency and dispersion are compared
with that of a soft PVC sheet. The result can be seen in
- table 4. The clearness of the sheet is improved, when the
. ~ 29 proportion of methylmethacrylate is increased. It attains
.. . .
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. .
4'~
- 17 - HOE 77/F 214 K
nearly the value of a soft PVC sheet in the case of a pro-
portion of MMA of 15 %.
Table 4
5 Example Transparency Dispersion
6: Comparison: CPE 89 51
7: 90 % CPE/10 % MMA 90 23
8: 85 % CPE/15 % MMA 90 16
Comparison: 70 % PVC/30 % DOP 92 10
E X A M P L E 9:
Example 2 is repeated with the exception that after
cooling of the aqueous liquor to 50 to 60C there are
added as stabilizers 1 weight % of Ca/Al stearate, 0.5
weight % of distearyl-pentaerythritol-diphosphite, 0.25
weight % of tetrakis-/methylene-3-3',5'-di-tertiary butyl-
4'-hydroxyphenyl) propionate/ methane and 3 weight % of a
- solid epoxidized ~olefin having from 26 to 28 carbon
atoms, while stirring for half an hour to one hour. The
thermostability and the rheological properties determined
- after the polymer has been treated in usual manner are the
same as that determined upon subsequent stabilization of
the powder.
E X A M P L E S 10 and 11-
_ _ .
- Example 5 is repeated, except that instead of pure hy-
droxypropylmethacrylate (HPMA) there is polymerized a
mixture Or hydroxypropylmethacrylate and methylmethacrylate
29 (MMA) in the presence of the chlorinated polyethylene.
:
..
.. ...
~14C~
- 18 - HOE 77/F 214 K
Table 5 shows the water vapor permeability of the products
prepared, in comparison with that of the products obtained
in Examples 2 and 5. The water vapor permeability can be
optimized according to the intended use by varying the
monomer ratio.
Table 5
Example water vapor permeability of
a sheet of 400 /um thickness
g/m2 . 24 h
2: 80 % CPE/20 % MMA 0.33
10: 80 % CPE/18 % MMA/ 2 % HPMA 0.51
11: 80 % CPE/10 % MMA/10 % HPMA 1.14
5 _80 % CPE/20 ~ HPMA 2.03 _ _
~ . .
`. E X A M P L E S 12 to 14:
_ _ _ _ _ . _ _
Example 5 is repeated except that there is polymeriz-
ed a mixture of ethylacrylate (EA) and methylmethacrylate
in the presence of the chlorinated polyethylene. The
yield, calculated on the monomer mixture and the light
- dispersion can be seen in table 6.
Table 6
`:
25 Example Yield Dispersion
% %
12: 80 % CPE/18 % MMA/2 % EA 99 19
13: 80 % CPE/16 % MMA/4 ~ EA 97 21
29 14: 80 ~ CPE/14 % MMA/6 % EA 96 22
- ' . . .
4~
- 1g - HOE 77/F 214 K
E X A M P L E S 15 and 16:
_ _
80 Parts of a chlorinated polyethylene having a chlor-
ne content of 34 % and a refractive index nD of 1.5222
which has been prepared by chlorinating a low pressure
polyethylene having a RSV value of 1.5 dl/g are mixed on
mixing rolls at 175C with 20 parts of polymethylmeth-
acrylate (nD 1.492; average molecular weight 100,000) and
squeezed into sheets of 400 /um thickness. A milky sheet
is obtained whose mechanical and physiological properties
correspond to those of the graft polymer of the same compo-
sition. This mixture may be used when a good transparency
is not required. When the polymethylmethacrylate is replac-
ed by a copolymer whose refractive index is adpated to that
of the chlorinated polyethylene, there are obtained transpa-
rent sheets. To demonstrate this, a copolymer consistingof 70 weight ~ of methylmethacrylate and 30 weight % of
furfurylmethacrylate (FMA) (nD of the homopolymer 1.5381)
is mixqd on mixing rolls with the same chlorinated poly-
ethylene. Table 7 shows the results obtained.
Table 7
Example Mixture Dispersion
~ 15: 80 % CPE/20 % PMMA 100
- 25 16: 80 % CPE/20 % copo of 70 % MMA and 30 ~ FMA 28
E X A M P L E 17:
97 Parts by weight of a fine grained chlorinated poly-
29 ethylene having a chlorine content of 36 weight ~ and a
~ .
:
- .
.
.. ; 1~,~4C~
- 20 - HOE 77/F 214 K
residual crystallinity of 8 % (deterrnined by differential
thermoanalysis), which has been obtained by chlorinating a
low pressure polyethylene having a RSV value of 1.5 dl/g
(determined in a 0.1 g solution in decahydronaphthalene at
135C), are suspended in 160 parts of water and 0.05 part
of a partially saponified polyvinylacetate (viscosity 2 cP
in 2 % aqueous solution, acetyl content 42 %) in a stainless
steel vessel having a content of 40 liters, by means of an
anchor agitator. 3 Parts by weight of methylmethacrylate
are introduced under pressure with the exclusion of oxygen
and the chlorinated polyethylene is swollen in the monomer
while stirring at room temperature. Thereafter 0.02 part
by weight of tertiary butylperpivalate is added and poly-
merization is initiated by heating the contents of the
vessel to 90C. After 2 hours, the resulting mixture is
allowed to cool and the fine grained product is withdrawn,
washed and dried. The yield, calculated on the feed
monomer, is 99.9 ~.
~! The product is stabilized with 1 weight % of Ca/Al
stearate, 0.5 weight % of trisnonylphenyl phosphite,
3 weight % of epoxidized soybean oil and 0.1 weight % of
tetrakis-/ methylene-3-(3'-5'-di-tertiary butyl-4'-hydroxy-
phenyl)propionate 7 methane (Irgano ~ 1010).
The polymer obtained is rolled on mixing rolls at 175C
to form a rough sheet and the latter is squeezed into
sheets of 400 /um thickness. The obtained sheet has the
- following properties, which are important for its use
according to the invention:
29 dispersion 25 %, transparency 89 %, MFI (150C/30 kp) 130
. - .
~-- ~ . - - :
.: . . :
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. . - ~ - .
~ 14 ~
- 21 - HOE 77/F 214 K
(g/lO'), shore hardness (Shore A) 67, tencile strength
8.5 N/mm2 "lotched impact strength: 12 (Nmm/mm2),
elongation at break: 490 %.
.. . .
. .
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.
