Stock material or miscellaneous articles – Composite – Of polyester
Reexamination Certificate
1998-09-25
2002-02-26
Chen, Vivian (Department: 1773)
Stock material or miscellaneous articles
Composite
Of polyester
C428S195100, C525S413000, C525S415000, C525S425000, C525S432000, C525S434000, C525S437000, C525S444000, C525S450000
Reexamination Certificate
active
06350530
ABSTRACT:
TECHNICAL FIELD
The present invention relates to biodegradable card bases.
BACKGROUND ART
Credit cards, bank cards, prepaid cards, commuter passes, ID cards, patient's registration cards, etc. are used in everyday life.
These cards usually comprise, as a support material, a card base formed from a sheet comprising polyethylene terephthalate, polyvinyl chloride or like plastics or a sheet of paper coated with a resin. Specific examples are cards bearing glossy, clear color print of photographs or data for identification, which are obtained by thermally transferring photographs and characters using a hot stamp and hot-melt or heat-sublimable color films, and removing the films. For example, bank cards, credit cards or like thick cards can be prepared from card bases obtained by laminating a core layer (A) of polyvinyl chloride optionally printed on one or both sides, and overlay layers (B) of polyvinyl chloride optionally having a magnetic recording layer (magnetic strips) bonded by thermocompression. Such card bases are cut into cards, and provided with embossed characters for debossing the characters, or hot-stamped with photographs, where necessary.
When cards cut out from the card bases consisting of sheets of polyethylene terephthalate, polyvinyl chloride or like plastics are discarded after use, they are disposed of by landfill or incineration, together with other types of garbage. Also, wastes produced when cutting the card bases into cards are disposed of in the same manner.
In the case of incineration disposal, the card bases comprising plastics generate high combustion heat and tend to damage incinerators. In the case of the landfill disposal, polyethylene terephthalate, polyvinyl chloride and like plastics are not degradable in the earth and remain therein. Further, for recovering pulp from card bases comprising resin-coated paper, it is necessary to collect only the paper for separation, since resins are not degraded in alkaline solutions.
For solving the above problems, highly degradable plastics have been recently proposed as materials for biodegradable card bases. Examples of such plastics include copolymers of 3-hydroxybutylate (3-HB) and 3-hydroxyvalerate (3-HV) (hereinafter referred to as “3-HB/3-HV copolymers”); polycaprolactones; lactic acid polymers; and like biodegradable polymers. However, card bases prepared from 3-HB/3-HV copolymers are brittle and have poor bending resistance; card bases prepared from lactic acid polymers have poor solvent resistance; and card bases prepared from polycaprolactones have low rigidity (Young's modulus). These plastics are therefore unsuitable for card bases.
Further, thick cards having a heat-sensitive recording layer or a magnetic recording layer for receiving imprinting when so required, need to be capable of retaining the recorded data. Also, such cards are required to have excellent strength, rigidity and durability since they are usually carried with the owner. Further, they must have impact strength sufficient to bear embossed characters.
The cards obtained by cutting the card base may have color print of photographs or data for identification formed by thermal transfer technique, which usually comprises the steps of thermally transferring photographs and characters to the surfaces of the cards by hot stamping using films of cyan, yellow, magenta and carbon black, for example in this order, and removing the films. However, it is impossible to form glossy, clear photographs or characters on the card bases comprising the above biodegradable polymers, since inks cannot be fixed thereto because of poor amenability of the card bases to color printing.
An object of the present invention is to provide a card base which is degradable by microbes in natural environment; has properties necessary for card bases, such as strength, rigidity (Young's modulus), bending resistance and durability; and is well-balanced in mechanical strengths.
Another object of the present invention is to provide a card base which is excellent in surface gloss, surface protection properties, strength, rigidity, and capability of bearing embossed characters formed as required; and is degradable by microbes in natural environment.
The embossed characters are formed on the cards when so required, in order to imprint the characters on sales slips or journal slips in CD or ATM, as visual proofs of use of the cards.
The card base of the invention can bear glossy, clear color print of photographs or data for identification, which are formed by a thermal transfer technique such as hot-stamping. The card base of the invention is excellent in properties necessary for cards, such as tensile strength, impact strength, flex temperature, lamination properties, heat resistance, resistance to thermal expansion and contraction, chemical resistance, blocking resistance and humidity resistance; has rigidity, bending resistance, durability, etc.; and is degradable by microbes in natural environment.
DISCLOSURE OF INVENTION
The present invention provides a biodegradable card base (hereinafter referred to as “the first invention”) comprising a composition containing 86 to 31 wt. % of a 2-hydroxybutyrate/3-hydroxyvalerate copolymer, 9 to 46 wt. % of a lactic acid polymer and 5 to 23 wt. % of a polycaprolactone, as essential components.
The present invention also provides a biodegradable card base (hereinafter referred to as “the second invention”) comprising core layer(s) (A1) comprising a composition containing 90 to 40 wt. % of a 3-hydroxybutyrate/3-hydroxyvalerate copolymer and 10 to 60 wt. % of a lactic acid polymer as essential components; and overlay layers (B1) comprising a composition containing 95 to 60 wt. % of a lactic acid polymer and 5 to 40 wt. % of a polycaprolactone as essential components; the core layer(s) (A1) being sandwiched between the overlay layers (B1).
The present invention further provides a biodegradable card base (hereinafter referred to as “the third invention”) comprising core layer(s) (A2) comprising a composition containing a 3-hydroxybutyrate/3-hydroxyvalerate copolymer, a lactic acid polymer and a high-molecular aliphatic polyester obtained by dehydrating polycondensation of a glycol and an aliphatic dicarboxylic acid, and overlay layers (B2) comprising a composition containing a lactic acid polymer and a high-molecular aliphatic polyester obtained by dehydrating polycondensation of a glycol and an aliphatic dicarboxylic acid; the core layers (A1) being sandwiched between the overlay layers (B1).
The 3-HB/3-HV copolymer for use in the present inventions (first to third inventions) is, for example, an aliphatic polyester biodegradable resin with a melting point of 100 to 180° C. biosynthesized by microbes such as hydrogen bacteria (
Algaligenes eutrophus
). The 3-HV/3-HV copolymer contains preferably 1 to 20 mol % of 3-hydroxyvalerate, from the viewpoint of processability. If the proportion of 3-hydroxyvalerate is less than 1 mol %, the card base becomes stiff and brittle because of high crystallinity of the polymer. Further, the polymer is likely to be deteriorated by heat in the molding process, because of its high melting point. If the proportion exceeds 20 mol %, the card base becomes soft because of low crystallinity and melting point of the polymer. However, the above range is not limitative.
The lactic acid polymer for use in the first to third inventions is preferably a polylactic acid, such as a lactic acid monopolymer obtained by direct dehydrating polycondensation of L-lactic acid, D-lactic acid or D,L-lactic acid, or a polymer obtained by ring-opening polymerization of lactide, i.e., a cyclic dimer of lactic acid. Also usable are copolymers obtained by direct dehydrating polycondensation of one of the above lactic acids and another hydroxycarboxylic acid (such as glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid, 4-hydroxyvaleric acid or 6-hydroxycaproic acid), and copolymers obtained by ring-opening polymerization of a lactide with a copolymerizable monomer selected from cyclic e
Morikawa Akira
Oishi Mamoru
Saito Yoshikiyo
Chen Vivian
Gunze Limited
Nexsen Pruet Jacobs & Pollard LLC
O'Toole J. Herbert
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