Note: Descriptions are shown in the official language in which they were submitted.
1049707
This invention relates to a novel, inorganic filler-
incorporated pullulan type resin composition having
excellent properties.
Because of their characteristic properties, molded
plastics composed of thermoplastic resins such as, for
example, polyolefin type, polystyrene type and polyviryl
chloride type resins have heretofore been put into
various uses such as containers, sheets, leathers, fu~n-
iture materials, soundproof materials, heat-insul~ting
materials, packing material, buffer materials, etc.
These molded plastics are composed of said thermo-
plastic resins, which themselves are hydrophobic, and -
hence can successfully be put into uses where their
hydrophobic property is utilized, but are restricted in
uses where moisture or water absorptivity is required. -~
In order to dismissenvironmental pollution gener- ~-
ated due to abandonment of molded plastics composed of
synthetic resins, there has recently been adopted such
process tha~ thermoplastic resins are incorporated with
inorganic fillers to decrease the amount of heat gener-
ated at the time of combustion of said molded plastics.
When the said process is adopted, incinerators may be
minimized in damage but the thermoplastic resins cannot
completely be made free from generation of environmental
pollution.
Further, molded plastics composed of pullulan type
resins are more easily water soluble than those composed
of conventional thermoplastic
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1049707
resins, are non-toxic and edible, do not generate poisonous gases
even when subjected to combustion, and can spontaneously be
decomposed by microorganisms even when discarded as they are.
Accordingly, the said molded plastics are expected as pollution-
free molded plastics substitutable for the conventional petro-
chemical products, but are limited in uses because of their
insufficient mechanical strength.
On the other hand, there have been known molded
articles composed of starches or combination of starches with
inorganic fillers. However, buffer materials prepared by use of
starches as substrates are insufficient in tensile strength,
rigidity and impact strength, and thus cannot be said to be
sufficient in buffer characteristics. Furthermore, the said
molded articles have such drawbacks that they are low in dimension
stability, and even when complex designs or patterns are applied
thereto by embossing or punching, it is difficult to reproduce x-
accurate dimensions or shapes.
With an aim to overcome the above-mentioned drawbacks
of molded articles composed of conventional thermoplastic resins,
pullulan type resins and starches, the present inventors continued
extensive studies to find that the said drawbacks can be avoided
by the use of a composition containing a pullulan type resin
incorporated with an inorganic filler.
Accor~ing to the present invention
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1049707
there is provided a pullulan type resin composition improved in
tensile strength, impact strength and rigidity which comprises a
pullulan type resin which is pullulan an etherified, esterified,
phosphatized, oxidized or graft-copolymerized pullulan 1 to 30
parts by weight per 100 parts by weight of the pullulan type
resin of a plasticizer for the pullulan type resin, and S to 90
parts by weight per 100 parts by weight of the pullulan type
resin of an inorganic filler.
The pullulan referred to in the present invention is
such as high molecular weight linear polymer that units of
maltotriose, which is a trimer of glucose, have been repeatedly
bonded through~-1,6 linkages which are different from those of
said trimer, and has such molecular structure as represented by
the formula,
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iO49707
N /~
O
tq~
N ~
tq L~q ~-
q ~
' o
~q tq~$
f , ' ~
~ to~ O
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tq ~ ' .
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~7 ~
O :-: . . -
O o ~ O
~Y
O
~t
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.
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9~0~
wherein n represents the polymerization degree and is
an integer of 20 to 10,000.
The pullulan used in the present invention is not
particularly limited in process for production thereof.
At present, for example, it can be isolated and recover-
ed as a tacky substance secreted in a culture liquor of
a strain belonging to the genus Pullularia which is an
incomplete
microorganism. That is, a strain of the species
Pullularia pullulans is subjected to shaking culture-at
24 C. for 5 days in a medium containing 10% of partially
hydrolyzed starch or glucose, 0.5% of K2HP04, 0.1% of
NaCl, 0.02: Of MgS04,7H20, 0.06%of (NH4)2S04 and 0.04
of yeast extract, whereby pullulan is obtained as a
tacky substance secreted from the cells into the cult- -
ure liquor.
If necessary, the cells are removed by centrifuga-
tion from the culture liquor, and the supernatant is
subjected to methanol precipitation and separation,
whereby purified pullulan can be obtained. Pullulan
somewhate differs in physical properties depending on
the kind of strain used. In the present invention,
however, the said difference is not greatly concerned
with the properties of the resulting resin composition.
The molecular weight of the pullulan used in the pre-
sent invention is not particularly limited, but is
preferably from lO,000 to 5,000~000.
While the pullulan is easily soluble in cold water,
it is well known that it can be varied in
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1049707
water solubility when modified by etherification,
esterification or graft-copolymerization with a vinyl
compound. Accordingly, the pullulan type resin refer-
red to in the present invention indicates not only
pullulan but also a partially modified pullulan pre-
pared by subjecting pullulan to etherification, esteri-
fication, phosphatization, oxidation, or graft-copoly-
merization.
The plasticization temperature of the pullulan
type resin used in the present invention varies depend
ing on the mole¢ular weight of pullulan, the kind of
pullulan modification, the degree of modification, and
the kind and amount of plasticizer added, but can be
freely adjusted to a temperature in the range from 40C.
to the decomposition temperature thereof, in general.
The decomposition temperature of the pullulan type ~-
resin means a temperature at which the resin, when ~ ~
gradually heated, starts to generate heat and to cause ~ -
marked loss due to oxidative decomposition. The decom-
position temperature of pullulan is in the range from
250 to 260 C., and that of the modified pullulan is in
the range from 170 to 300 C., though this varies
depending on the kind and degree of modification.
Examples of the plasticizer for pullulan type resin
referred to in the present invention, include water;
polyhydric alcohols such as glycerin, ethylene glycol,
polyethylene glycol, sorbitol, propylene glycol and
polypropylene glycol; amides
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1049707
such as dimethylformamide and formamide; amines such
as triethylenetetramine, diethylenetriamine, ethanol-
amine, propylamine, propylenediamine, butylamine and
ethylamine; and dimethyl sulfoxide. These plasticizers
may be used either singly or in the form of a mixture
of two or more members. The amount of the plasticizer
to be incorporated into the resin composition is not
particularly limited, but is preferably 1 to 30 parts
by weight per 100 parts by weight of the pullulan type
resin.
Examples of the inorganic filler used in the pres-
ent invention include aluminum hydroxide, calcium
hydroxide, magnesium hydroxide, barium hydroxide, cal-
cium sulfate, calcium sulfite, calcium carbonate, silica
calcium silicate, basic magnesium carbonate, kaolin
clay and talc. These may be used ei-ther singly or in
the form of a mixture of two or more members. The
average particle size of the inorganic filler is pre-
ferably 50~ or less, more preferably 5~ to 0.01 ~ .
In order to sufficiently display the characteristics
of the present invention, the inorganic filler is used
in a proportion of 5 to 90 parts by weight, perferably
20 to 60 parts by weight, per 100 parts by weight of
the pullulan type resin.
The composition of the present invention may be
incorporated with any various stabilizers, flame re-
tardants, dyes, pigments antiseptics, lubricants, foam-
ing agents, etc., which are ordinarily used in this
field.
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1049707
In the present invention, the process of incor-
porating the plasticizer into the pullulan type resin
is not particularly limited. That is, in case water
is used as the plasticizer for example, there may be
adopted a process in which the resin is moistened by
allowing to stand in a high humidity atmosphere, or a
process in which the resin ~s sprayed with water by use
of sprayer to uniformly absorb water in the resin~.
Further, the process of mixing the pullulan type resin
with the inorganic filler is not particularly limited.
However, it is preferably to mechanically mix the two
by use of Henschel mixer, a drum blender or a home
mixer.
The thus prepared blend comprising a pullulan type
resin, a plasticizer for the pullulan type resin,
and an inorganic filler is melted and kneaded by use
of an extruder h~Ving a plasticizing screw, whereby
pellets of the pullulan type resin incorporated with
the inorganic filler can be obtained. These pellets
are molded into a molded article by adoption of such
molding process as extrusion molding using a screw
type extruder, injection molding using a screw type
injection molding machine, blow molding using a blow
molding machine, or press molding using a press. The
molding process may be properly selected according
to the desired shape and use of the resulting molded
article.
The composition obtained according to the
present invention is markedly excellent in mechanical
properties such as tensile strength, rigidity hardness
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10~9707
and impact strength, thermal properties such as heat
distortion temperature, chemical properties such as
adhesiveness, printability and combustibility, and
moldability such as molding shrinkage and dimension
stability. Particularly, the composition is far more
excellent in tensile strength, rigidity and impact
strength than a composition prepared by incorporating
an inorganic filler into starch, which is a water-sulu-
ble high polymer. It has heretofore been entirelyunknown and hence is quite surprising that many such
properties as above can be greatly improved at one time.
For further clarification, the present invention is
illustrated in more detail below with reference to
examples, but the invention is not limited to the
examples.
Example`l
500 Grams of a dry pullulan powder having a mole-
cular weight of 90,000 was uniformly sprayed with
water by use of a sprayer to a water content of 100 g.
The thus wetted powder was mixed bu use of a home mixer
with 150 g of aluminum hydroxide having an average
particle size of 7~. The resulting mixture was intro-
duced into a screw type extruder (screw diameter 30 mm, -
L/D = 20) equipped at the tip with a die having a
diameter of 4 mm, and was extruded to the form of a
strand with a screw rotation number of 30 r.p.m. at -
a resin temperature of 80 C. Subsequently, the strand
was cut to a length of 3 mm to
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1049707
form granular pelle-ts. These pellets were subjected
to compression molding at a temperature of 80 C to
prepare a molded article. The molded article was
measured in physical properties according to the
methods regulated in JIS and ASTM (the same shall
apply herei~nafter) to obtain such results as shown in
Table l.
Example 2
500 Grams of dry pullulan powder having a mole-
cular weight of 300,000 was uniformly sprayed with
ethylene glycol by use of a sprayer to an ethylene
glycol content of 100 g. The thus wetted powder was
mixed by use of a home mixer with lO0 g of aluminum
hydroxide having an average particle size of 7~ .
The resulting mixture was formed into pellets in the
same manner as in Example 1 (except that the mixture
was extruded to the form of a strand at a resin temper-
ature of 150 C). These pellets were subjected to com-
pression molding at a temperature of 120C to prepare
a molded article. The molded article was measured in
physical properties to obtain such results as shown ~ ~ -
in Table l.
Example 3
500 Grams of a dry pullulan powder having a mole-
cular weight of 90,000 was uniformly sprayed with
ethylene glycol by use of a sprayer to an ethylene
glycol content of 100 g. The thus wette~ powder was
mixed by use of a home mixer with 50 g of aluminum
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1~4970 7
hydroxide having an average particle size of 7~. The
resulting mixture was formed into pellets in the same
manner as in Example 1. These pellets were subjected
to compression molding at a temperature of 80 C to
prepare a molded article. The molded article was
measured in physical properties to obtain such results
as shown in Table 1.
Example 4
A molded article was prepared in the same manner
as in Example 3, except that 150 g of aluminum hydroxide
having an average particle size of 7~was used as the
inorganic filler. The molded article was measured in
physical to obtain such results as shown in Table 1.
Example 5
A molded article was prepared in the same manner as
in Example 3, except that 250 g of aluminum hydroxide
having an average particle size of 7~X was used as the
inorganic filler. The modled areticle was measured in
physical properties to obtain such results as shown in
Table 1.
Example 6
A molded article was prepared in the same manner
as in Example 1 J except that 150 g of calcium carbonate
having an average particle size of 3,~(was used as the
inorganic filler. The molded arcicle was measured in
physical properties to obtain such results
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1049707
as shown in Table l.
Example 7
A molded article was prepared in the same manner
as in Example l, except thaO 150 g ~f talc having an
average particle size of 3~(was used as the inorganic
filler. The molded article was measured in physical
properties to obtain such results as shown in Table 1.
Example 8
A molded article was prepared in the same manner
as in Example 1, except that 150 g of calcium sulfate
having an average particle size of 6~ was used as the
inorganic filler. The molded article was measured in
physical properties to obtain such results as shown in -
Table 1.
Reference Example 1 -
A molded article was prepared in the same manner
as in Example 1, except that the inorganic filler was
not used, The molded article was measured in physical
properties to obtain such result as shown in Table 1.
Reference Example 2
A molded article was prepared in the same manner
as in Example 2, excpet that the inorganic filler was
not used. The molded article was measured in physical
properties to obtain such results as
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1~49707
shown in Table 1.
Reference Example 3
500 Grams of a soluble starch having a molecular
weight of about 60,000 ( a reagent produced by Nakarai
Kagaku Co.) was uniformly sprayed with water by use of
a sprayer to a water content of 100 g. The thus wetted
powder was mixed by use of a home mixer with 150 g of
aluminum hydroxide having an average particle size of
7 ~ . The resulting mixture was formed into pellets
in the same manner as in Example 1. These pellets
were subjected to compression molding at a temperature --
of 80 C to prepare a molded article. The molded article
was measured in physical properties to obtain such
results as shown in Table 1.
Refernce Example 4
A molded article was prepared in the same manner as
in Reference Example 3, except that ethylene glycol was
used as the plasticizer. The molded article was
measured in physical properties to obtain such results
as shown in Table 1.
Reference Example 5
A molded article was prepared in the same manner as
in Réference Example 3, except that talc having an
average particle size of 3~(was used as the inorganic
filler. The molded article was measured in physical
properties to obtain such result as shown in Table 1.
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1049707
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1049707
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