Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-07-20
2003-08-19
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S055000, C524S056000, C524S058000, C524S385000, C524S386000, C524S387000, C524S492000, C524S557000
Reexamination Certificate
active
06608121
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a water-soluble resin composition comprising a polyvinyl alcohol polymer (hereinafter, polyvinyl alcohol polymer is abbreviated as “PVA”, in some cases) and a specific ingredient incorporated therein and to a water-soluble film produced by using the water-soluble resin composition.
2. Description of the Prior Art
In recent years, a technique of packaging unit doses of various chemicals or agents, typically agrochemicals, in sealed water-soluble film containers has acquired more and more popularity. When the unit dose packages as such are thrown into water, the packaging film is dissolved in water and the contents are dissolved or dispersed in water to produce the intended effects. The advantageous features of such unit dose packages consist in that even a hazardous agent can be applied or used without directly touching the same, that no metering is necessary prior to application of an agent since a predetermined amount of the agent has already been packaged and that the disposal of the containers, bags or the like used for packaging and transporting an agent is unnecessary or simple and easy.
In the art, unmodified partially hydrolyzed PVA films with a degree of hydrolysis of about 88 mole percent have been used as water-soluble films for such unit dose packaging. These water-soluble films are readily soluble in cold or warm water and, from the viewpoint of the performance characteristics, they are excellent in mechanical strength, among others. However, in view of the recent growing concern about environmental pollution, of the fact that partially hydrolyzed PVA films, when placed under high humidity conditions, absorb moisture from the air and lose their stiffness and stick to rolls and thus show worsened processability and of the current trend toward the use of such films in packaging alkaline detergents and other household articles, films which satisfy a number of performance characteristics requirements, such solubility in water and high biodegradability, stiffness, slight odor emission and alkali resistance, are demanded. As far as such requirements are concerned, unmodified partially hydrolyzed PVA species are sufficiently soluble in water and biodegradable. However, films thereof are disadvantageous in that they lack stiffness and emit the odor of acetic acid and that when they are used for packaging alkaline substances, their water solubility lowers. The reason why unmodified partially hydrolyzed PVA films lack stiffness is presumably that the degree of hydrolysis of the unmodified partially hydrolyzed PVA is low and the water content of films thereof increases accordingly.
A method of improving the water solubility of partially hydrolyzed PVA films is disclosed in Japanese Examined Patent Application (Kokoku)06-27205(Japanese Unexamined Patent Application (Kokai)63-168437) which comprises producing water-soluble films by using a modified PVA as obtained by introduction of the sulfonic group by copolymerization, for instance. This method can improve the water solubility by introducing a modifying group and, therefore, can improve the stiffness by increasing the degree of hydrolysis while improving the water solubility as well. However, it is generally known that copolymerization of PVA with a comonomer results in a decrease in biodegradability and this tendency becomes remarkable with an ionic group-containing comonomer, in particular. Thus, water-soluble films made of such modified PVA may possibly fail to show satisfactory biodegradability.
Under such circumstances, it is an object of the present invention to provide a water-soluble resin composition useful in producing water-soluble films simultaneously satisfying those requirements with respect to such physical properties as water solubility, biodegradability, processability, odor emission and alkali resistance which have not been simultaneously fulfilled by water-soluble films made of the conventional PVA, as well as a water-soluble film made of such water-soluble resin composition.
SUMMARY OF THE INVENTION
The present inventors made intensive investigations and, as a result, found that a water-soluble resin composition comprising PVA having a specific 1,2-glycol linkage content and a specific degree of hydrolysis, with a specific proportion of a plasticizers and a specific proportion of a monosaccharide and/or a polysaccharide incorporated therein, a water-soluble resin composition further comprising a specific proportion of an inorganic filler incorporated therein in addition to the constituents mentioned above, or a water-soluble resin composition comprising a PVA having a specific 1,2-glycol linkage content and a specific proportion of a plasticizer and a specific proportion of an inorganic filler are very useful as a raw material for producing the desired water-soluble films. This finding has led to completion of the present invention.
Thus, the present invention provides a water-soluble resin composition which comprises (i) 100 parts by weight of a polyvinyl alcohol polymer having a 1,2-glycol linkage content of at least 1.8 mole percent and a degree of hydrolysis of at least 90 mole percent, (ii) 1 to 50 parts by weight of a plasticizer and (iii) 5 to 50 parts by weight of a monosaccharide and/or a polysaccharide (hereinafter, such water-soluble resin composition is abbreviated as “composition A1”, in some cases) as well as a water-soluble film made by using the above water-soluble resin composition (hereinafter, such film is abbreviated as “film A1”, in some cases).
The present invention also provides a water-soluble resin composition which comprises (i) 100 parts by weight of a polyvinyl alcohol polymer having a 1,2-glycol linkage content of at least 1.8 mole percent and a degree of hydrolysis of at least 90 mole percent, (ii) 1 to 50 parts by weight of a plasticizer, (iii) 5 to 50 parts by weight of a monosaccharide and/or a polysaccharide and (iv) 1 to 20 parts by weight of an inorganic filler (hereinafter, such water-soluble resin composition is abbreviated as “composition A2”, in some cases and the composition A1 and composition A2 are collectively abbreviated as “composition A”, in some cases) as well as a water-soluble film made by using the above water-soluble resin composition (hereinafter, such film is abbreviated as “film A2”, in some cases and the film A1 and film A2 are collectively abbreviated as “film A”, in some cases).
The present invention further provides a water-soluble resin composition which comprises (i′) 100 parts by weight of a polyvinyl alcohol polymer having a 1,2-glycol linkage content of at least 1.8 mole percent and a degree of hydrolysis of 92 to 99 mole percent, (ii′) 1 to 50 parts by weight of a plasticizer and (iv′) 1 to 20 parts by weight of an inorganic filler (hereinafter, such water-soluble resin composition is abbreviated as “composition B1”, in some cases) as well as a water-soluble film made by using the above water-soluble resin composition (hereinafter, such film is abbreviated as “film B1”, in some cases).
Still further, the invention provides a water-soluble resin composition which comprises (i′) 100 parts by weight of a polyvinyl alcohol polymer having a 1,2-glycol linkage content of at least 1.8 mole percent and a degree of hydrolysis of 92 to 99 mole percent, (ii′) 1 to 50 parts by weight of a plasticizer, (iv′) 1 to 20 parts by weight of an inorganic filler and 5 to 50 parts by weight of a monosaccharide and/or a polysaccharide (hereinafter, such water-soluble resin composition is abbreviated as “composition B2”, in some cases and the composition B1 and composition B2 are collectively abbreviated as “composition B”, in some cases) as well as a water-soluble film made by using the above water-soluble resin composition (hereinafter, such film is abbreviated as “film B2”, in some cases and the film B1 and film B2 are collectively abbreviated as “film B”, in some cases).
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
The PVA to be us
Fujiwara Naoki
Hikasa Shintaro
Isozaki Takanori
Somemiya Kazuyuki
Kuraray Co. Ltd.
Szekely Peter
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