Note: Descriptions are shown in the official language in which they were submitted.
107~786
This invention relates to transparent thermoplastic moulding
compounds which comprise organic cellulose esters and ethylene/
vinyl ester copolymers and optionally low molecular weight plasti-
cizers.
5~ It is well known that cellulose can be thermoplastically
processed only after it has been esterified with certain organic
acids, and even then, in many cases only after incorporation of
low molecular weight plasticizers into the esterified product.
The three hydroxyl groups of the anhydroglucose units of cellulose
I
are capable of being esterified with numerous organic acids but
in practice only cellulose acetates, cellulose acetopropionates
and cellulose acetobutyrates are used to any significant extent
for this purpose. These esters are used to produce moulding com-
¦ pounds which can be thermoplastically processed as well as pro-
ducts such as acetate silk, block acetate, foil substrates forsafety films, electric lnsulating foils and lacquers.
Moulding compounds of cellulose acetate cannot be
thermoplastically processed without the addition of low mole
cular weight plasticizers because cellulose acetate begins to
deco~pose before it softens. Cellulose acetopropionates and
cellulose acetobutyrates also have their softening point and
decomposition point fairly close together so tha-t moulding
ccmpounds prepared from these esters must also be mixed with
low molecular weight plasticizers before they are thermo-
plastically processed. The addition of such plasticizers
reduces the operating temperature and viscosity as required.
The plasticizers used for organic cellulose esters are
mainly the aliphatic esters of phthalic acid, adipic acid,
azelaic acid, sebacic acid and phosphoric acid~ for example
dimethylphthalate, diethylphthalate, dibutyl adipate, dioctyla-
Le A 15 757
..
``" ` 107~786
dipate~ dibutylazelate~ trichloroethyl phosphate and tributylphosphate. It
is also advantageous to use mixtures of plasticizers.
Although cellulose ester moulding compounds which have been modified
with plasticizers are sufficiently transparent~ it would for many purposes be
desirable to improve their dimensional stability under heat. Furthermore,
the plasticizers migrate to the surface of the moulded articles over a period
of time so that, for example, foils made of modified cellulose esters cannot
be used for packaging certain foodstuffs.
Mixtures of organic cellulose esters~ low molecular weight plasti-
cizers and olefine polymers have been described in German Auslegeschrift No.
1?303,219 = British patent specification No. 1,004,204. However, such mould-
ing compounds are no longer transparent if they have a high olefine polymer
content. Moreover, the plasticizers used in these mixtures are the conven- `
tional low molecular weight esters, which have the weIl known disadvantages.
It has now surprisingly been found that transparent moulding com-
pounds which can be thermoplastically processed as required can be obtained
without the disadvantages mentioned above if cellulose esters are mixed with
copolymers of ethylene and vinyl esters.
This invention therefore relates to thermoplastic moulding com-
pounds consisting essentially of
1) 1 to 99 percent by weight, preferably 50 to 98.99 percent by
weight~ of at least one cellulose ester of an aliphatic carboxylic
acid,
2) 99 to 1 percent by weight, preferably 1 to 50 percent by weight of
an ethylene/vinyl ester copolymer containing 30 to less than 72
percent by weight~ preferably 60 to 70 percent by weight of vinyl
esters arld
3) o to 35 percent by weight, preferably 0.01 to 20 percent by weight
of a low molecular weight plasticizer. The sum of components 1)
-- 2 --
~.~
~,.
1071786
to 3) is 100 percent by weight.
Thermoplastic moulding compounds which are particularly preferred
consist essentially of
1) 95 to 70 percent by weight, preferably 94.99 to 70 percent by
weight of at least one cellulose ester of an aliphatic acid,
2~ 5 to 30 percent by weight of an ethylene/vinyl acetate copolymer
containing 30 to less than 72 percent by weight, preferably 60 to
70 percent by weight of vinyl acetate and
3) 0 to 20 percent by weight~ preferably 0.01 to 20 percent by weight
of a low molecular weight plasticizer. The sum of components 1) to
3) is 100 percent by weight.
One particularly surprising feature of the moulding compounds ac
cording to the invention is their transparency and their very good mechanical
properties.
Suitable cellulose esters for the preparation of the moulding com-
pounds according to the invention are cellulose esters of aliphatic carboxylic
; acids containing 1 to 5 carbon atoms, particularly cellulose acetate, cellu-
lose acetopropionate and cellulose acetobutyrate.
Processes for the preparation of organic cellulose esters have been
known for a long time and have been described, for example, in Ullmanns
Encyklop~die der technischen Chemie (Publishers Urban ~ Schwarzenberg, Munich-
Berlin, 1963) in Volume 5 on pages 182 to 201.
Preferred cellulose acetobutyrates contain
40 to 50% of butyric acid,
- 3 -
1071786
15 to 26~ of acetic acid and
~.75 to 1.95~ of hydroxyl.
Cellulose acetobutyrates of the following composition
are particularly suitable for the moulding compounds according
to the invention: `
42 to 46% of butyric acid~
18 to 21~ of acetic acid and
-~ 1.O to 1.7~ of hydroxyl.
~ Preferred cellulose acetopropionates generally contain
-;10~ 50 to 63.5~ of propionic acid,
1 to 12~ of acetic acid and
1.2 to 1.95~ of hydroxyl
and particularly preferred cellulose acetopropionates have the
following comp~sition:
54 to 5~ of propionic acid,
; 5 to ~ of acetic acid and
' 1.5 to 1.8% of hydroxyl.
1~ i The c~llulose acetates used are preferably secondary
,, j
cellulose acetates.
Th~ percentages given here and in the following are
percentages by weight and parts are parts by weight.
' ! . ,
The relative viscosities (~ rel) of 2 % solutions of the
aliphatic cellulose esters used in acetone at 25C are between
` 3.5 and 4.5 and preferably between 4.0 and 4.5.
~- 25 The vinyl esters used may be organic vinyl esters of satu-
rated, optionally halogenated, in particular chlorinated, alipha-
tic monocarboxylic acids containing 1 to 18 carbon atoms or aro-
matic monocarboxylic acids containing 7 to 11 carbon atoms. The
following are specific examples: Vinyl formate, vinyl acetate,
vinyl propionate, vinyl chloropropionate, vinyl butyrate,
-
~ Le A 15 757 _ 4 _
1071786
vinylisobutyrate, vinyl caproate, vinyl laurate, vinyl myristate,
vinyl stearate and vin~l benzoate. Vinyl acetate is preferred.
The ethylene/vinyl ester copolymers are prepared by the
known methods of high or medium pressure synthesis, optionally in
solve~ts such as tertiary butanol.
Ethylene/vinyl ester copolymers prepared by high pressure
synthesis have melt index values (according to DIN 53 735 at 190C
and under a load of 2.16 kp) of between 0.1 and 100, preferably
between 1.0 and 10 and more particularly between 4.5 and 6. Their
intrinsic viscosities measured in tetralin at
120C are generally between 0.6 and 1.5. The molecular weights
determined by the light diffusion method are preferably between
50,000 and 1,000,000. The non-uniformity U defined by the term
/Mn ~ 1 (G.Schulz, Z. phys. Chem (B) 43 (1939) pages 25-34) is
in the region of 5 to 30. These copolymers dissolved most easily
; in hot hydrocarbons.
Ethylene/vinyl ester copolymers prepared, for example, by
the process of solution or emulsion polymerisation, which contain
e.g. 30 to 98 % by weight and preferably 60 to 80 % by weight of
vinyl esters, may have melt index values (190C 2.16 kp) greater
than 100 and the melt index is preferably below 15 and in parti-
cular between 0.5 and 5. The molecular weights determined by the
method of light diffusion are preferably between 40,000 and
1,000,000. The non-uniformity U is 1 to 6. The copolymers are
soluble in hydrocarbons and alcohols and preferably have intrin-
sic viscosities of between 0.5 and 2.5, measured in toluene
at 25C.
The ethylene/vinyl acetate copolymers may be partly or
completely 20 to 100 % saponified if desired.
Composition and melt indices of the ethylene/vinyl acetate
copolymers used:
¦ Le A 15 757 - 5 -
~' .
,.. . ,, . . , .. _ . __. _ ~
1071786
. . .
Name Vinyl acetate M~I
~ content [~]
-- ,
EVA - 800 78 0 ~15
E~A - 700 70 3
5 EVA - 600 60 10.4
EVA - ~l50 4~ 0 54
EVA ~ ~38 33 64
EVA - 80 8 5
In tHe above table:
E~A: Ethylene/vinyl acetate copolymer
MFI: Melt index [g/10 min] according to DIN 53 735 under a
load of 2.16 kp and at a temperature of 190C.
Suitable low molecular weight plasticizers include
dimethylphthalate; diethylphthalate; triphenylphosphate;
methyl phthalyl ethyl glycollate; di-n-butylsebacate;
ethylphthalyl ethyl glycollate; butyl phthalyl butyl
glycollate; dibutylphthalate; dioctyladipate; dioctyl-
I phthalate; butylbenzyl phthalate and triacetin.
Preparation of the moulding compounds according to the
invention from organic cellulose esters and ethylene/vinyl
ester copolymers which may, if desired, be modified with low
molecular weight plasticizers is carried out by vigorously
mixing the components. Any known mixing method may be
used on rollers or in serew extruders,
The mixtures may also be prepared via their solutions.
In that case, the components are dissolved in suitable solvents
or solvent mixtures, and the polymer mixtures may be precipi-
tated with suitable non-solvents or the solvents or solvent
mixtures may be removed by evaporation. Methylene chloride
Le A 15 757 - 6 -
. ~ .
~ ' 107~786
and ~laciai acetic acid, for example, are suitable solvents
for organic cellulose esters and ethylene/vinyl ester copolymers.
The mutual precipitating agent used may be hexane, for example,
if the components have been dissolved in methylene chloride.
The mixtures according to the invention may also
contain certain other additives to colour or pigment the
polymer mixtures or improve their resistance to oxidation,
light or combustion and the li~e.
The moulding compounds according to the invention prepared
from ethylene/vinyl ester copolymers and organic cellulose
esters show a remarkable increase in the notched impact
strength measured according to DIN 53 453.
In addition, the moulding compounds according to the
invention are distinguished by their improved dimensional
; 15 stability at elevated temperature determined e.g. as the
Vicat softening temperature according to DIN 53 460.
The Vicat softening temperatures are up to 40C higher
than the corresponding softening temperatures of cellulose
esters which have been modified with low molecular weight
- 20 plasticizers.
Compared with conventional cellulose ester moulding
compounds which contain low molecular weight plasticizers,
~ the polymer mixtures according to the invention also show
; improved mechanical properties such as an increase in their
~` 25 hardness, tensile strength, flexural strength and modulus
of elasticity.
The polymer mixtures of organic cellulose esters and
ethylene/vinyl ester copolymers are virtually free from
the well known effect of so-called plasticizer migration and
3o the moulding compounds are therefore also particularly
Le A 15 757 _ 7 _
1071786
~ suitable, for example, for purposes in which they come into con-
: tact with foodstuffs.
~ I The improved resistance of the mixturesto hot air makes it
; possible for them to be used for outdoor garments,
5 I The moulding compounds according to ~the invention can be
used for the production of shaped articles of any kind and for
the production of acetate silk, block acetate, foil substrates
for safety films, packaging material, electric insulating foils
and lacquers.
Mixtures of organic cellulose esters and ethylene/vinyl
; ester copalymers can be processed contînuously or batchwise in
~: known extruders and injection moulding machines without any sub-
:~ stantial difficulty and have good fluidity properties under these
conditions.
l ~ '
:
~ '
,
.
~ ~ Le A 15 757 - 8 -
.
... .. . . _ .
~; ~ 1071786
..
;~ Examples l_to 15 , I
"'`'`'`''''''` .. I
Cellulose acetobutyrate containing 42 to 46~ of butyric
acid, 18 to 21~ of acetic acid and 1~0 to 1.7% o~ hydroxyl
groups is vigorously mixed with ethylene/vinyl acetate co-
polymers on rollers at 170C as indicated in the following
Table.
¦ The rolled sheets are granulated and then extruded in
an injection moulding apparatus at a mass te~perature of 230C
¦ 10 to form test samples.
In the examples marked L, the polymer mixtures are
prepared as solutions and then precipitated. The appropriate
-~; parts by volume of 10~ methylene chloride solutions of
'i~ cellulose acetobutyrate and of ethylene/vinyl acetate co-
polymer are mixed and the polymer mixture is precipitated
with hexane. The resulting mixtures are dried and then
extrudéd to form test samples as mentioned above.
~ .
...,
,~ ~ """
i Le A 15 757 - ~ -
,
:
` ~`` ` 1071786
~ I I I 1 1-1
' ~i U~ O O Ll~ O O O O O Lt~ O O 1-~ 0 .- 2
~ _ _ .
a ~
o I $ o ~ 1;
~ 1 _ _
i Lr~ (~ Lr~ 11~ ~U '-- . . (~ Lr~ LS'~
¦~ -- Ll~ Lt~ Lt\ LS~ r ~ ~ Lr~ ~ U~ =i
¦ h ~ ~ D Ll~ C' Lr~ L ~ 0 0 1~ ~ ID L~\ 1
~ _ _ ~ i ~
. ~ ¦ ~1 <~ ~j ~ O 11~ a~ L O O ~ a) :;1 O ~ Lr~
_' ~ _ ~
N~ O ~ ~ t N ~ N O (~ ~ O ~ ¦_
~i , ~ ' ~ j ~ a ~a ¦~a ~ 'a
;~ ~ a~ 0 0 O o ~ ~o ~ t ~ ~ ~ oo
:~ -
~ . ~i O O O Oo o o ~ LD r~ r~
:
:
r~ ; X ~ ~ ~ D C~ 0 CS~ O O ~ ~ L
~ ' , ' - --___
~,"q Le A 15 757 10
~`~ 1071786
~ 1 , I .
~ ~.
. ~egend to Table:
'' a~.~ Imp~ct strength accordin~ to DIN 5~ 453;
Dimension: ~kJ/m2].
ak: Notched impact strength accordinæ to DIN 53 453;
Dimension: [kJ/m2].
Vicat: Vicat softening temperature according to Method B .¦
(Force: 49.05 N) according to DIN 53 460;
Dimension: [C]. I
~b~: Bending yield stress according to DIN 53 452;
Dimension: [N/mm2~.
.. ~ . f : sagging at ~b~:
. Dimension; ~mm~.
Hk30: Ball pressure hardness after 30 s according to
DIN 53 456; 2
Dimension: [rl/mm ].
~ ~ 3y~ ~ deno~es giass clear transparcncyr~ - denotes opaque.
.'
~ . . ' ,.
,.,,f .
~} .~,
.-i^;~,'. ' .
J'~.,,, .
2 ~ .
''''
I Le A 15 757 _ 11 -
.
i,;,,.~ '
~, ,,
,,~' ' .
:
~ 1071786
`-` .. I
.-, Examples 16 to 29:
Cellulose acetopropionate containing 54 to 58~ of
propionic acid, 5 to 8% of acetic acid and 1.5 to 1.8~ of
free hydroxyl groups is vigorously mixed with ethylene/vinyl
acetate copolymer on a roller at 180C as indicated in the
following Table.
The rolled sheets are granulated and then extruded in
~j~ an injection moulding machine at a mass temperature of 240C
, - 10 to form test samples.
In the Examples marked L, the polymer mixtures are
prepared. as solutions which are subsequently precipitated~
as described in Examples 1 to 15.
.~
~i,.b'. ,: ~ . . ~ . , .
'`
rc
~,,,,,,,
,`-','''.
: ,
.
~ . Le A 15 757 - 12 -
'', ~ ~ ._
107~786
r ~ ~ _ _ _ _
`~"
. ~ + + + I + + + + + ~ + + + +
~i i F.~ .
.5 _ _ . _
~ O ~ ~ O ~ 0 0 o tr~ u~ O a~
, ~ CO ~ C~ D C- ~O ~ ~ C'
, _
~ C~ ~ ) 0 ~ J ~ .
~ . '- - . . - - . -
~ , . q~ ~ 01~ u~ ~ U\ ;i;i .
~ _ , _ .
~ ~r '0 ~ g ~ ~ ~ ~00 ~9 ~ ~ ~D J ~D ~o
~ .
_ I
~ ~ O ~ O O ~ J O N ~ o i~ ~ ~
:~ _
~ ~ ~0 ~ J ~ ~ ~U ~ co ~ Ir~ Ct)
~' _ _. _ _
. ~ d d ~ d ; 1 ~ S~
. ~ h h h ~ h ~ ~0 J ~ ~ :i J
~ . _. _
~ ~ u~ ~ 2 ~ ~ U' 2 u~ o ~ 2 ~
~ ~ ~ . ,
~y
~, 0 CO ~ o o ~ ~ ~ ~ $
~ ~ o o o o o o o o o o o o o 0 0
~ o o o o o o o o o ~ ~ ~ u~ ~ ~
0~) 0 0 ~) C~~ C~~ C~ ~ ~ ~ ;i- J
'" i ~1 _ _ _ ._
:g~i ~O ~ C' 0 Ci~ N ~\J N N J ~ N rN' ~0\J (U
, t~i
~, ; - . _ _ _
"." ` .
~ Le A 15 757 _ 13 _
1071786
5~ When similar cellulose acetopropiDnates are mixed with
,the low molecular weight plasticizer dibutyladipate, the test
samples obtained have much lower Vicat softening points.
'~
% DibutyladipateVicat C
~ 5 100
82
. . 15 68
54
~ ,. 10
. ~ . Examples 30 to 33:
Secondary cellulose acetate is vigorously mixed with
ethylene/vinyl acetate copolymer on a roller at 220C as
indicated in the following Table~
The rolled sheets are granulated and then extruded in
an injection moulding apparatus at a mass temperature of
230C to produce test samples.
In the examples marked L, the polymer mixtures are
~ prepared as solution which are then precipitated, as
described in Examples 1 to 15~
''~ ' '
~ `~i' ,
,. j ,
`''''''
` Le A 15 757 - 14
~ .`` . 1071786
~ 1`+~+++1
1~ ~ .. . ,., . I
'~ o00~ .
I ~9 ~ 0
. .
.
.~ ~ o~ , I
~r. . __ . ~
',~ . ~ ~ '
~, I i~ .~
I
I! cu ~ (U
_ . _
. ~ Lr~O~O
~ . , _ . . .
~ ~ ~ 0 0~Q0 0~0
. t:l.
~ ~ r i _ _ ~
~j ~ O ~U
_
¢ O O O O O
~ ~i 0 ~ 0 ~
j ~ ., I O O ~
~5 ~
' . ~ _ _ ' . .
..
.
Le A 15 757 - 15 ~
, ~ ~
, - .... ........ ~
