CA1049707A

CA1049707A - Pullulan type resin composition

Info

Publication number: CA1049707A
Application number: CA237,414A
Authority: CA
Inventors: Hiroomi Matsunaga; Kozo Tsuji; Masashi Watanabe
Original assignee: Sumitomo Chemical Co Ltd; Hayashibara Biochemical Laboratories Co Ltd
Current assignee: Hayashibara Seibutsu Kagaku Kenkyujo KK; Sumitomo Chemical Co Ltd
Priority date: 1974-10-11
Filing date: 1975-10-10
Publication date: 1979-03-06
Also published as: GB1504158A; FR2287472A1; DE2545502B2; FR2287472B1; DE2545502A1; JPS5144163A; DE2545502C3

Abstract

PULLULAN TYPE RESIN COMPOSITION

ABSTRACT OF THE DISCLOSURE
A resin composition comprising a pullulan type resin, a plasticizer for said resin, and an inorganic filler. The said resin composition is markedly excellent in mechanical properties such as tensile strength, impact strength and rigidity, thermal properties such as heat distortion tempera-ture, chemical properties such as adhesiveness, printability and combustibility, and moldability such as molding shrinkage and dimension stability.

Description

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 - 1 - ~ . -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 .' ' ' ~'.
:

--, .

- 2 -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, ' _ 3 _ iO49707 N /~

O

tq~

N ~
tq L~q ~-q ~
' o ~q tq~$

f , ' ~
~ to~ O
tq_~_ ~ -tq ~ ' .
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~7 ~
O :-: . . -O o ~ O

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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 ,: :

.

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 - .
- ~ " , . .
-: . ... .. . - , 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.

' 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 - 8 _ ;, .

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 g 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 . ' , .

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 .~: , . . - . :
. ~

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 ~ . ~ - ,. .

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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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. 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 5 to 90 parts by weight per 100 parts by weight of the pullulan type resin of an inorganic filler.

2. A composition according to claim 1, wherein the pullulan type resin is pullulan an etherified, esterified, phos-phatized, oxidized or graft-copolymerized pullulan.

3. A composition as claimed in claim 2 in which the pullulan has a molecular weight from 103 to 5 x 106.

4. A composition according to claim 1, 2 or 3 wherein the plasticizer is at least one member selected from the group consisting of water, glycerin, ethylene glycol, polyethylene glycol, sorbitol, propylene glycol, polypropylene glycol, dimethyl-formamide, formamide, triethylenetetramine, diethylenetriamine, ethanolamine, propylamine, propylenediamine, butylamine, ethylamine and dimethyl sulfoxide.

5. A composition according to claim 1, 2 or 3 wherein the inorganic filler is at least one member selected from the group consisting of aluminum hydroxide, calcium hydroxide, magnesium hydroxide, barium hydroxide, calcium sulfate, calcium sulfite, calcium carbonate, silica, calcium silicate, basic magnesium carbonate, kaolin clay and talc.

6. A composition according to claim 1, 2 or 3 wherein the inorganic filler is used in a proportion of 20 to 60 parts by weight per 100 parts by weight of the pullulan type resin.

7. A composition according to claim 1 which is incorporated with a stabilizer, a flame retardant, a dye, a pigment, an antiseptic, a lubricant or a foaming agent or a mixture thereof.

8. A composition according to claim 1, 2 or 3 wherein the filler has an average particle size of not more than 50 µ.

9. A composition according to claim 1, 2 or 3 wherein the filler has an average particle size of not more than 5 µ to

10 µ.