JP2000136299A - Degradable recording sheet and recording card - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a degradable recording sheet having excellent ink adhesion and fixity, and to obtain a recording card by disposing the sheet on the surface of a card substrate, wherein letters and patterns can be easily printed on the recording card. SOLUTION: The characteristic of the degradable recording sheet comprises adding 1-30 pts.wt. of a polyvinyl alcohol-based polymer of the formula [(m)+(n) are each a positive number satisfying the inequalities: [(m)+(n)]>=150 and 97>=100(m)/[(m)+(n)]>=40 to 100 pts.wt. of a 100/0 to 60/40 mixture of a polylactic acid-based polymer with another aliphatic polyester having a glass transition temperature of <=0 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a degradable recording sheet and a recording card.

[0002]

2. Description of the Related Art Sheets made of biodegradable polymers which have been actively studied in recent years have been replaced with polyolefins, polystyrenes, aromatic polyesters, polyvinyl chlorides, and the like. It has begun to be used for thermoformed products. Above all, aliphatic polyesters are particularly intensively studied since they are nontoxic and have a low molecular weight after biodegradation.

As biodegradable polyester resins, polyesters obtained by ring-opening polymerization of cyclic lactones, synthetic aliphatic polyesters, polyesters biosynthesized in cells, and condensation of aliphatic polyfunctional alcohols and aliphatic polyfunctional carboxylic acids. And polyester obtained by the above method. Further, there are polyglycolic acid and polylactic acid obtained by directly or indirectly polymerizing oxycarboxylic acids.

[0004] Specifically, polyesters obtained by ring-opening polymerization of cyclic lactones include poly-ε-caprolactone, poly-δ-valerolactone, and poly-β-methyl-.
δ-valerolactone and the like. Examples of the synthetic aliphatic polyester include a cyclic acid anhydride and an oxirane, such as a copolymer of succinic anhydride and ethylene oxide. Examples of the polyester biosynthesized in the cells include polyhydroxybutyrate, polyhydroxybutyrate / valylate, and the like. Further, as a polyester obtained by condensing an aliphatic polyfunctional alcohol and an aliphatic polyfunctional carboxylic acid, succinic acid or adipic acid, or a dicarboxylic acid component composed of both,
Representative examples include aliphatic polyesters having a main structural unit of a diol component composed of ethylene glycol or butanediol, or both. Further, as a different polyester, as an acid component, a compound such as suberic acid, sebacic acid, dodecanedioic acid, or a polyester obtained by condensing an anhydride or a derivative thereof, hexanediol, octanediol, cyclohexanedimethanol is added to an alcohol component. And the like, and polyesters obtained by condensing these derivatives, and for the purpose of providing a branch in the polymer for improving the melt viscosity, a very small amount of tri- or more functional carboxylic acid or hydroxycarboxylic acid is copolymerized. The resulting polyester and the like can be mentioned.

[0005] However, these aliphatic polyesters have a low glass transition point, a high flexibility at room temperature or lower, and a little lack of rigidity as a sheet. Therefore, when used for the above-mentioned applications, it is not rare that a sheet is thickened, or an inorganic filler or the like is mixed to increase the stiffness of the sheet.

On the other hand, in contrast to these aliphatic polyesters, polylactic acid having a glass transition point of not lower than room temperature is rich in rigidity, has a sufficient rigidity even when the thickness is relatively thin, and has a high rigidity from polystyrene, aromatic polyester, and PVC. There is no inferior to a sheet. However, polylactic acid has a drawback that it is very fragile by itself as long as it is not stretched or oriented, and is liable to be cracked or chipped even by a slight impact.

To solve this problem, Japanese Patent Application Laid-Open No. 9-11 / 1991
As disclosed in, for example, Japanese Patent Application Publication No. 1107, it is an effective method to mix an aliphatic polyester having a glass transition point of 0 ° C. or less with polylactic acid as exemplified above. However, although the biodegradable sheet thus obtained is also highly practical in terms of physical properties, there are still problems in printing on this surface. The surface of polylactic acid etc. has low polarity, and general-purpose resin sheets used so far (specifically, polystyrene, amorphous polyester, and PVC sheets)
Printing ink for printing does not provide sufficient adhesion, and although the ink is fixed on the sheet, it may be easily peeled off.

[0008] To improve this, it is also possible to select a binder that forms the ink on the polylactic acid / aliphatic polyester sheet and mix the ink again. Ten to hundreds of colors,
Recombining them one by one requires labor and time. It is also conceivable to perform a surface treatment to make the surface of the sheet more polar. Methods for increasing the surface polarity include chemical (chemical) treatment, active gas treatment, primer treatment, discharge treatment and the like.

Specifically, a method of oxidizing and etching the surface by using a chemical such as an acid, an alkali, and an oxidizing agent to improve the affinity with ink or the like, oxidizing the surface with ozone, plasma, ultraviolet light, or the like; A method of etching to increase the affinity with the binder contained in the ink, etc., A method of applying a compound having an affinity to both the binder contained in the ink, etc. and the adherend to improve the fixability and adhesion Furthermore, as represented by corona treatment, radicals (especially oxygen radicals) are generated in the air by the discharge, which collide with the surface to generate hydroxyl groups, carbonyl groups, etc., increase the polarity, and increase the polarity with the ink binder. There is a method of increasing the affinity of the compound.

[0010] In these methods, for example, a resin is extruded into a sheet by an extruder, and then continuously passed through a processing apparatus, or once wound up, or a sheet cut to a predetermined size is processed. Processed through the device. However, in particular, it is troublesome to apply the cut sheet to the processing apparatus again. Further, to arrange these processing devices requires a workplace and cost for the same.

[0011]

An object of the present invention is to obtain a sheet having excellent ink adhesion and fixing properties without performing these treatments. Therefore, it is an object of the present invention to make it possible to easily print characters and designs after producing a card.

[0012]

Means for Solving the Problems As a result of diligent studies, the present inventors have found that the above problems can be solved by adding a polyvinyl alcohol-based polymer, and have completed the present invention. That is, the gist of the present invention is that a polylactic acid-based polymer and another aliphatic polyester having a glass transition point of 0 ° C. or lower are 100% or less.
/ 0 to 60/40, a polyvinyl alcohol-based polymer represented by the following general formula (1) is added to the mixture 100
1 to 30 parts by weight based on the weight of the degradable recording sheet.

[0013]

Embedded image

[In the general formula (1), m and n represent m
It is a positive number that satisfies + n ≧ 150 and 97 ≧ 100 m / (m + n) ≧ 40. ]

The term "mixture" is used in the present invention, and this includes the case where the quantitative ratio of the polylactic acid-based polymer to the aliphatic polyester having a glass transition point of 0 ° C. or lower is 100/0. I have. That is, the above “mixture” is defined as “a polylactic acid-based polymer or a polylactic acid-based polymer having a glass transition point of 0.
° C or lower and other aliphatic polyesters ".

Another embodiment of the present invention is a degradable recording card characterized in that the above-mentioned sheet is laminated on one or both sides of a core layer as a support. The core layer is a main component when configuring the thickness of the card, and determines the mechanical properties of the card. Usually, the core layer refers to an intermediate layer in which over layers are provided on both surfaces, and in the present invention, it is defined as a support layer to which the over layer serving as a printing surface is bonded.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
The recording sheet in the present invention is a character sheet on the surface of the sheet.
Including designs where the pattern is simply printed, those with magnetic tape attached at the same time, those with IC chips attached or embedded, and those with a heat-sensitive recording layer and some information recorded . In addition, even before printing or bonding, or before inputting these information records, these are treated as recording sheets for the purpose.

Polylactic acid having a glass transition temperature of room temperature or higher is a decomposable polymer that can obtain a transparent base sheet, depending on the molding method. The structural units of polylactic acid include two types of optical isomers, L-lactic acid unit and D-lactic acid unit, and the crystallinity differs depending on the ratio of these two types of structural units. For example, a random copolymer having a ratio of L-lactic acid unit to D-lactic acid unit of about 80:20 to 20:80 has no crystallinity at all and has a glass transition point of about 60 ° C.
It becomes a semi-crystalline polymer having a melting point of 180 ° C. or higher. This semi-crystalline polylactic acid becomes an amorphous material having excellent transparency by being immediately cooled immediately after being melt-extruded.

A more preferable method for obtaining a transparent polylactic acid material is to heat-treat the molecule after uniaxially or biaxially stretching polylactic acid to orient the molecules.
This makes it possible to crystallize while suppressing the growth of spherulites having a size equal to or greater than the wavelength of visible light. Therefore, the recording sheet of the present invention is preferably subjected to the same stretching and heat treatment.

The polylactic acid-based polymer in the present invention may be a polymer obtained by copolymerizing not only the above-mentioned polylactic acid but also other hydroxycarboxylic acids to such an extent that the required properties of the polylactic acid are not impaired. Specific examples include glycolic acid, 3-hydroxybutyric acid, 4-hydroxybutyric acid, 3-hydroxyvaleric acid, 4-hydroxyvaleric acid, and 6-hydroxycaproic acid. In addition, small amounts of chain extenders, for example,
The molecular weight may be increased by using a diisocyanate compound, an epoxy compound, an acid anhydride or the like. The weight average molecular weight of the polylactic acid polymer is preferably in the range of 60,000 to 700,000. When it is below this range, practical physical properties are hardly exhibited, and when it is above this, the melt viscosity is too high and the moldability is poor.

The method for producing polylactic acid is not particularly limited, and various known methods such as an entrapment polymerization method and ring-opening polymerization can be employed. For example, in the condensate polymerization method, L-lactic acid, D-lactic acid or a mixture thereof can be directly dehydrated and condensed to obtain polylactic acid having an arbitrary composition. In the ring-opening polymerization method, lactide, which is a cyclic dimer of lactic acid, can be polymerized in the presence of a selected catalyst using a polymerization regulator or the like, if necessary, to obtain polylactic acid. Lactide includes L-lactide which is a dimer of L-lactic acid, D-lactide which is a dimer of D-lactic acid, and DL which comprises L-lactic acid and D-lactic acid.
Lactide, and polylactic acid having any composition and crystallinity can be obtained by mixing and polymerizing these in an appropriate ratio. In particular, after biaxially stretching polylactic acid,
By performing heat treatment, crystallization can be performed while maintaining transparency, and heat shrinkage can be suppressed. In this case, considering the crystallinity, the ratio of the L-lactic acid unit to the D-lactic acid unit in the polymer is 100: 0 to 90:10 or 10:90 to
It is particularly preferred that the ratio be in the range of 0: 100. Also,
Most preferably, the ratio of the L-lactic acid unit to the D-lactic acid unit in the polymer is 100: 0 to 94: 6 or 6:94 to 0:
100.

However, a non-stretched sheet made of only polylactic acid is very brittle and easily cracked. Also, in the case of amorphous polylactic acid, the rigidity is extremely reduced when the temperature exceeds the glass transition point. As a countermeasure, it is preferable to mix a biodegradable aliphatic polyester having a glass transition point of 0 ° C. or less other than the polylactic acid polymer, provided that the melting point of the degradable aliphatic polyester is 80 ° C. or more. More preferred. That is, a component that is flexible at least at room temperature is required to improve brittleness, and at least 80 ° C. or higher to suppress a decrease in rigidity due to components mixed even beyond the glass transition point of polylactic acid. Those having a melting point are preferred. Examples of a material that can bring about such an effect include a crystalline aliphatic polyester. The crystalline aliphatic polyester is not particularly limited, as long as it can improve the impact resistance of polylactic acid and maintains rigidity at more than 60 ° C., and two or more kinds may be mixed. Usually, those having a glass transition point of 0 ° C or lower, preferably -20 ° C or lower are used. In order to maintain the rigidity at more than 60 ° C., it is effective to have a melting point (flow starting temperature) of 80 ° C. or more.

The preferred weight average molecular weight of the aliphatic polyester in the present invention is 50,000 to 1,000,000, preferably 7
If it is too small, the melt tension is low, and it is difficult to take out the sheet when melt-extruded, and if it is too large, the melt viscosity is too high and molding processability is poor. The glass transition point and melting temperature of the aliphatic polyester vary depending on the composition and molecular weight, but are about -60 to 0C and about 80 to 170C. Specific examples of the aliphatic polyester in the present invention include an aliphatic polyester obtained by condensing an aliphatic diol and an aliphatic dicarboxylic acid, an aliphatic polyester obtained by ring-opening polymerization of a cyclic lactone, a synthetic aliphatic polyester, and a bacterial cell. Examples of the aliphatic polyester biosynthesized in the above include those having a glass transition point of 0 ° C. or lower, and are preferably aliphatic polyesters obtained by condensing an aliphatic diol and an aliphatic dicarboxylic acid.

The aliphatic polyester obtained by condensing an aliphatic diol and an aliphatic dicarboxylic acid is an aliphatic diol such as ethylene glycol, 1,4-butanediol,
It is obtained by condensation polymerization of one or more of 1,4-cyclohexanedimethanol and the like and one or more of aliphatic dicarboxylic acids such as succinic acid, adipic acid, suberic acid, sebacic acid, dodecandioic acid and the like. Most preferably 1,4
-Condensation polymerization of butanediol and succinic acid or adipic acid. If necessary, the desired polymer can be obtained by jumping up with an isocyanate compound.

Examples of the aliphatic polyester obtained by ring-opening polymerization of a cyclic lactone include δ-valerolactone and β-methyl-δ-valerolactone, which are cyclic monomers.
One or more of these are selected for polymerization.

Examples of the synthetic aliphatic polyester include cyclic acid anhydrides and oxiranes, for example, copolymers of succinic anhydride with ethylene oxide, propylene oxide and the like.

As the aliphatic polyester biosynthesized in the cells, there is known an aliphatic polyester biosynthesized by acetyl coenzyme A (acetyl CoA) in cells such as alkaligenes eutrophus.
This aliphatic polyester is mainly poly-β-hydroxybutyric acid (poly 3HB), but in order to improve practical properties as a plastic, a valeric acid unit (HV) is copolymerized to obtain a poly (3HB-co-3HV). It is industrially advantageous to use the copolymer of (1). HV copolymers generally have a
40%. Further, a long-chain hydroxyalkanoate may be copolymerized.

The main component of the recording sheet of the present invention is a polylactic acid-based polymer of 60 to 100% by weight, preferably 70 to 90% by weight, particularly preferably 70 to 80% by weight, and a fat having a glass transition point of 0 ° C. or lower. Group polyester 40 to 0% by weight,
Preferably from 30 to 10% by weight, particularly preferably from 30 to 2% by weight.
Consists of 0% by weight. If the amount of the polylactic acid-based polymer is too small, the transparency is insufficient. Further, if the polylactic acid is partially crystallized, the transparency is further impaired. Therefore, the smaller the proportion of the aliphatic polyester within the above range, the more preferable.

Next, the printability will be described. Mixing the above-mentioned polylactic acid-based polymer or a mixture of the polylactic acid-based polymer and another aliphatic polyester having a glass transition point of 0 ° C. or lower with a polymer compound component which enhances the affinity with the binder contained in the ink. The adhesiveness and fixability of the ink when formed into a sheet can be improved. Examples of the selected high molecular compound include natural high molecular compounds such as polysaccharides such as hyaluronic acid, agarose, and proteins such as collagen. Examples of natural compounds include starch and cellulose obtained by graft polymerization of acrylonitrile, acrylic acid, vinylsulfonic acid, acrylamide, and the like. Examples of the synthetic polymer compound include a polyamide polymer, a polyvinyl alcohol (vinyl acetate) polymer, a poly (ethylene-vinyl alcohol) polymer, an acrylic polymer, a polyether polymer, and a maleic anhydride polymer. Polymers.

Among the above high molecular compounds, preferred are polyvinyl alcohol (vinyl acetate) polymers, poly (ethylene-vinyl alcohol) polymers, polyether polymers (polyethylene glycol, polypropylene glycol, etc.). And a mixture of the above-mentioned polylactic acid-based polymer or another aliphatic polyester having a glass transition point of 0 ° C. or lower. Among them, the most preferred is a polyvinyl alcohol-based polymer, which has biodegradability. Of the above polymer compounds, naturally-derived compounds are, of course, biodegradable, but in the case of mixing a polylactic acid-based polymer and a polylactic acid-based polymer with an aliphatic polyester having a glass transition point of 0 ° C. or lower, In particular, it cannot withstand the temperature range of 100 to 250 ° C. in the melt mixing apparatus used, has a property of easily deteriorating, and is not suitable for extrusion molding.

As the polymer compound used for the decomposable sheet having excellent printability, it is necessary to consider heat-melt mixing as well as biodegradability, and is a polyvinyl alcohol polymer represented by the following general formula (1). Is preferred.

[0032]

Embedded image

[In the general formula (1), m and n represent m
It is a positive number that satisfies + n ≧ 150 and 97 ≧ 100 m / (m + n) ≧ 40. ]

The polyvinyl alcohol polymer has a degree of polymerization (m + n in the above formula (1)) of at least 15
It is preferably 0, and particularly preferably 300 or more. If the degree of polymerization is low, after the sheet is formed, the surface is apt to ooze due to moisture or the like, and the ink is detached after printing. Further, the saponification rate, that is, the ratio of the hydroxyl group formed by saponification (100 m /
(M + n)) is preferably in the range of 40 to 97%. When it is smaller than this, not only the polarity is reduced and the fixing property of the ink is lowered, but also the glass transition point becomes close to room temperature (about 40 ° C. or less). Lowers the softening point and lowers heat resistance. On the other hand, when the proportion of m in the above general formula (1), that is, when there is a large amount of the hydroxyl group component, the polarity increases, and the adhesion and fixability of the printing ink to the sheet increase. However, when the number of hydroxyl groups increases, intramolecular and intermolecular hydrogen bonds increase, and the polyvinyl alcohol-based polymer crystallizes, and has a melting point higher than the decomposition temperature in a range where the fight ratio exceeds 97%. It becomes impossible to produce a sheet by substantially melt-extrusion. In a polyvinyl alcohol-based polymer that melts at a temperature lower than the decomposition temperature, the melt extrusion temperature of the aliphatic polyester (depending on their melting points) is in the range of approximately 100 to 250 ° C. From the melting point, a more preferred ratio of hydroxyl groups is 50 to 95% (approximately 14
0-200 ° C).

The ratio of mixing the polyvinyl alcohol-based polymer with the polylactic acid-based polymer or another aliphatic polyester mixture having a glass transition point of 0 ° C. or less is 100 parts by weight. The amount is 1 to 30 parts by weight, preferably 3 to 10 parts by weight. If the amount of the polyvinyl alcohol-based polymer is too large, the glass transition point of the polyvinyl alcohol-based polymer having a large amount of a vinyl acetate component is close to room temperature as described above, and the heat resistance is reduced. Further, the rigidity of the sheet is reduced, and the waist required for use as a card is insufficient. When the amount of the polyvinyl alcohol-based polymer is too small, the ink fixing property and the adhesion are not improved. In order to obtain the effect of improving the ink fixing property and adhesion, use a polyvinyl alcohol-based polymer with a high saponification rate as long as it can be melt-mixed and extruded without thermal decomposition, and do not reduce the heat resistance It is preferable to reduce the proportion of the compound as much as possible.

The recording sheet of the present invention may contain other polymers and additives in addition to the polylactic acid-based polymer, the aliphatic polyester having a glass transition point of 0 ° C. or lower, and the polyvinyl alcohol-based polymer. . Other polymers include biodegradable materials such as the aforementioned polysaccharides such as hyaluronic acid, agarose, protein collagen, and natural high molecular compounds such as starch and cellulose. There is no particular limitation as long as the properties, the rigidity of the sheet and, if necessary, the transparency are not impaired. Additive components include lubricants, ultraviolet absorbers, antioxidants, stabilizers, antibacterial agents, various pigments and colorants, and even metal particles,
Examples include inorganic compound particles and a crystal nucleating agent. The addition amount is 0.01 to 5 parts by weight.

The method for forming a sheet according to the present invention comprises the steps of preparing a polylactic acid-based polymer and a polyvinyl alcohol-based polymer, or a polylactic acid-based polymer, an aliphatic polyester, and a polyvinyl alcohol-based polymer, if necessary. Alternatively, the method can be performed by directly charging the extruder together with the additive component to form a sheet, or by extruding and cutting into pellets once into pellets, and then feeding the extruder again to form a sheet. Good. The melt extrusion temperature is
It is appropriately selected in consideration of the melting temperature and composition of the polymer in the composition, and is usually selected from the range of 100 to 250 ° C.

The polymer composition melt-formed into a sheet is preferably cooled by bringing it into contact with a rotating casting drum (cooling drum). The temperature of the casting drum varies depending on the type and composition of the polymer in the composition, but is usually preferably 60 ° C. or lower. At higher temperatures, the polymer sticks to the casting drum and cannot be pulled off. When the sheet is stretched, it is preferable that the polylactic acid portion be made substantially amorphous by rapid cooling so that crystallization of the polylactic acid portion is promoted and spherulites do not develop.

Next, the case where the sheet is stretched and heat-treated will be described. As described above, the rigidity of the amorphous sheet of polylactic acid rapidly decreases when the temperature exceeds the glass transition point, and in particular, polylactic acid that does not essentially crystallize starts flowing as it is. On the other hand, the advantage of stretched and heat treated polylactic acid sheet is that
JP-A-7-207041 and JP-A-7-2052
As described in JP-A-78-78, it is possible to crystallize while improving strength, improving brittleness, and maintaining transparency, and is suitable for use in transparent sheets, particularly as an overlayer of a card.

The stretching ratio of the sheet is, for example, longitudinal (longitudinal).
The stretching temperature is appropriately selected in the range of 1.5 to 5 times, preferably 2 to 4 times in the direction and the lateral (width) direction, and the stretching temperature is appropriately in the range of 50 to 90 ° C, preferably 55 to 80 ° C. The stretching step is a roll stretching in which the sheet is stretched between two rolls having a difference in peripheral speed, and / or a tenter stretching in which the gap between the rows of the clips is extended while the sheet is gripped with a clip using a tenter. Done by In the case of biaxial stretching, either simultaneous or sequential stretching method may be used. In the case of the sequential biaxial stretching method, the in-plane orientation degree Δn of the sheet after the first-stage stretching is 3.0 × 10 ⁻³ to 30.
× 10 ⁻³ , preferably 5.0 × 10 ⁻³ to 30 × 10
^-3 is preferred. If it is smaller than this range,
If the tensile strength and elongation are insufficient or large, problems such as breakage of the sheet during the second-stage stretching occur.

The tenter stretching method is advantageous because the sheet can be heat-set in the tenter after stretching the sheet with the tenter. In the heat setting, for example, the heat shrinkability of the sheet can be controlled (suppressed) by performing a heat treatment within a temperature range from the glass transition point to the melting point (Tm) for 3 seconds or more.

Next, the recording card will be described. These may be mixed with an inorganic filler such as titanium oxide, silicon dioxide, calcium carbonate, talc or the like to form a concealable sheet.

The above-mentioned sheet may be used as a core layer, and a transparent oversheet (the recording sheet of the present invention) may be adhered to one or both sides of the sheet. The bonding method mainly includes a method of heat fusion and a method of using an adhesive (especially, a hot melt type).
４０40 kgf / cm ^{2 at} a temperature of 80 ° C. or higher for several minutes to tens of minutes and bonded. It is preferable to print characters and designs on one or both sides of the core sheet by silk printing, offset printing, or the like.

When printed on the surface of the core layer, letters and designs printed on the surface of the core layer need to be seen through the over layer. Aliphatic polyester mixing,
In addition, the proportion of the polyvinyl alcohol polymer must be taken into account.

As a feature of the recording card of the present invention, since the over layer contains a polyvinyl alcohol-based polymer, when printing on this over layer is desired, the surface treatment such as corona treatment is not performed, It can be easily printed. In fact, screen printing, offset printing,
Necessary information and the like are written by using thermal transfer printing or the like.

The recording card of the present invention may be provided with a heat-sensitive recording layer, if necessary. In that case, it is preferable to provide the surface of the core layer or the over layer or between the layers. When a magnetic recording layer or the like is provided, a magnetic stripe is formed on the surface of the over layer by an appropriate method,
Preferably, the IC is embedded.

Although the thickness of the recording card of the present invention varies depending on the use, a thick card of about 500 μm to 900 μm is used for a cash card or a credit card, and a thick card for a telephone card or a prepaid card. , About 50 to 350 μm is used.
The thickness of the over layer is 20 to 140 μm in a thick one,
Even a thin one is preferably about 20 to 100 μm, but there is no particular limitation.

[0048]

The present invention will be described below in detail with reference to examples. The measurements and evaluations shown in the examples were performed under the following conditions. (1) Measurement of glass transition temperature Tg and melting point Tm of polylactic acid and aliphatic polyester were measured using a differential scanning calorimeter DSC-7 manufactured by Perkin Elmer. 10 mg of the sample was set, and the heating rate was 10
The temperature was raised to 200 ° C. at a rate of ° C./min, and the temperature was maintained for 2 minutes to completely melt the sample. At that time, the temperature drop rate is 10 ° C
The endothermic peak temperature of the melting that appears on the DSC curve when the temperature was decreased at a rate of / m was defined as the melting point Tm, and determined based on JIS K7122. The temperature was further lowered, lowered to -60 ° C. once, kept for 2 minutes, and raised again at 10 ° C./min.
21, the intermediate value of the transition curve is calculated as the glass transition temperature T.
g. In addition, liquid nitrogen was used as a cooling medium for performing the measurement at 0 ° C. or lower.

(2) Tensile modulus Using a Toyo Seiki Tensilon II type tensile tester, a temperature of 2
The measurement was performed at 3 ° C. and a relative humidity of 50%. 5m sheet
It was cut out into a strip having a width of 300 m and a length of 300 mm, and a tensile test was performed at a chuck distance of 250 mm and a tensile speed of 5 mm / min. The higher the value, the more rigid the sheet. The extruding flow direction of the sheet was represented by MD, and the vertical direction thereof was represented by TD.

(3) Fixability of Printed Designs / Characters The surface of the overlayer after being made into a sheet or card is patterned by silk printing using vermilion ink (Toyo Ink Mfg. Co., Ltd., brand name NEWLP super F523). -Characters were printed and left at 40 ° C for 24 hours. Nichiban Corporation
A pressure-sensitive adhesive tape (trade name, Cellotape) was strongly adhered to the printed portion, then the pressure-sensitive adhesive tape was quickly peeled off along the printed surface, and the remaining ink on the sheet surface was visually observed. A mark with ink remaining was marked with ○, and a mark with almost no ink remaining was marked with x.

(4) Impact Strength Place the sheet or laminated card on a solid horizontal plate,
When 500 g of a steel ball was dropped on the card from a height of 30 cm, the card was marked with "O" when the card did not crack or crack, and was marked with "X" when it did. This test complies with the credit card standard with magnetic stripe JISX6310.

(5) Heat Resistance In the evaluation of the above (3), the appearance and dimensional change of the sheet were examined under an atmosphere (solvent removal / aging) at 40 ° C. for 24 hours. Particularly, no change was indicated by ○, and one with impaired flatness was indicated by x.

(6) Clarity of Printed Portion of Core Layer This is an evaluation item for only the laminated card. After forming the card, the characters and designs printed on the core layer were visually observed through the over layer to see if they were clearly visible. ○ those that look sharp, Δ that looks slightly cloudy, and × that do not look sharp
It was written.

(7) Degradability test for burying in soil The test was conducted in accordance with the test method conducted by the Biodegradable Plastics Research Society. That is, the grassland which was sunny and slightly drained was excavated 10 cm, and then the excavated soil was sifted through a 1 cm sieve and returned to the excavated depth of 5 cm. The sample was placed on top of it, and the soil was returned while sieving again so that the sample was completely buried. The sample size is 30mm x
In the case of 120 mm and a thickness of 100 μm, about 450 mg
Becomes After standing for one year, the sample was taken out and the appearance was observed. Those in which the disintegration has progressed are indicated by "O", and those in which the disintegration has not occurred are indicated by "X".

Further, about 100 mg of the sheet after the test was taken out, sufficiently dissolved in 100 ml of chloroform, and filtered twice through a pore filter made of tetrafluoroethylene having an average pore diameter of about 0.5 μm to remove insoluble components. 100 ml of this chloroform and 100 ml of distilled water were put into a separating row, and the water-soluble components were extracted into distilled water. The water content of this aqueous solution was dried by heating to extract a water-soluble component. The molecular weight of this component was measured and compared with that before the test, and those showing a decrease in the molecular weight (retention rate of 90% or less) were indicated by ○, and those not observed were indicated by ×. The molecular weight was measured by gel permeation chromatography HLC-8120GPC
(Manufactured by Tosoh Corporation) and the molecular weight was compared with that of standard polystyrene. The measurement conditions are as follows.

Chromatography column: Shim-Pack series (Co., Ltd.)
Solvent: chloroform Sample solution concentration: 0.2 wt / vol% Sample solution injection volume: 200 μl Solvent flow rate: 1.0 ml / min Pump / column / detection temperature: 40 ° C.

In the case of using a resin (ethylene-vinyl alcohol copolymer) insoluble in a solvent, 50 mg of the sample after the test was dissolved in chloroform, and the insoluble component was taken out. The solution was decanted three times with chloroform, dried under reduced pressure, and the weight of the insoluble component was measured. At this time, if the weight ratio of the insoluble component to the charged amount is equal to or greater than the weight ratio of the insoluble component before the test, it indicates that there is no weight loss due to decomposition. Those with a weight loss were marked with ○, and those without weight loss were marked with x.

(8) Comprehensive Evaluation From the evaluation results of the above (2) to (6), one or more items indicated by x were marked with x, and the other items were marked with ○. The ones marked with X are those with low practicality, and those with ○ represent high practicality. The details of polylactic acid and aliphatic polyester used in the following examples are shown in Table 1,
Tables 2 and 3 show the evaluation results of the following examples and comparative examples. The resin components A to D in Table 2 correspond to (A) to (D) in Table 1, respectively.

Example 1: Sheet No. Production of No. 1 Polylactic acid (trade name: Lacti 1000, manufactured by Shimadzu Corporation) has a polymerization degree of about 500 and a ratio of hydroxyl groups (saponification rate) of about 8
A 0% polyvinyl alcohol polymer was mixed with a polybutylene succinate / adipate copolymer (trade name: Bionole # 3001, manufactured by Showa Kogyo Co., Ltd.) to 5 parts by weight, and the cylinder temperature was 210 ° C. and the die temperature was 200. The mixture was melt-kneaded with a twin screw extruder at the same temperature and extruded into a sheet shape while removing water from the vent holes with a vacuum pump, and extruded onto a cooling roll having a surface temperature of 58 ° C to obtain a transparent sheet of about 700 µm. This sheet was preheated by a metal roll, and then stretched 2.5 times in the longitudinal direction between rolls having a difference in peripheral speed while being heated by an infrared heater. Subsequently, the film was transversely stretched to 3.0 times with a tenter, and then heat-treated in the tenter to a thickness of 100 μm.
m of a stretched and heat-set sheet. The conditions for stretching and heat treatment were as follows.

Longitudinal stretching: stretching temperature 75 ° C., stretching ratio 2.5 times Transverse stretching: stretching temperature 72 ° C., stretching ratio 3.0 times Heat treatment: heat treatment temperature 130 ° C., heat treatment time 20 seconds

Example 2: Sheet No. Production of 2 A polybutylene succinate / adipate copolymer (trade name: Bionole # 3001, manufactured by Showa Polymer Co., Ltd.) was mixed with 20 wt% of polylactic acid (trade name: Lacti 1000, manufactured by Shimadzu Corporation) to 80 wt%. , And a degree of polymerization of about 170
0, 20 parts by weight of a polyvinyl alcohol-based polymer having a hydroxyl group ratio (saponification ratio) of about 80% are mixed and melt-kneaded at a cylinder temperature of 210 ° C. and a die temperature of 200 ° C. using a twin screw extruder in the same direction. And extruded on a cooling roll having a surface temperature of 35 ° C. to obtain a sheet having a thickness of 100 μm.

Comparative Example 1: Sheet No. Production of 5 Degree of polymerization about 1700, ratio of hydroxyl group (saponification rate) about 80%
Instead of 20 parts by weight of the polyvinyl alcohol polymer, a polymerization degree of about 2,000 and a ratio of hydroxyl groups (saponification rate) of about 5
A sheet having a thickness of 100 μm was obtained in the same manner as in Example 2, except that 40% by weight of a 0% polyvinyl alcohol-based polymer was mixed.

Comparative Example 2: Sheet No. Preparation of 6 Degree of polymerization about 1700, ratio of hydroxyl groups (saponification rate) about 80%
Instead of 20 parts by weight of the polyvinyl alcohol-based polymer, a polymerization degree of about 1700 and a hydroxyl group ratio (saponification rate) of about 3
A sheet having a thickness of 100 μm was obtained in the same manner as in Example 2 except that 20% by weight of a 0% polyvinyl alcohol-based polymer was mixed and the cylinder temperature was set to 200 ° C.

Comparative Example 3: Sheet No. Production of 7 30% by weight of polybutylene succinate / adipate copolymer (Bionore # 3001, manufactured by Showa Polymer Co., Ltd.) was mixed with 70% by weight of polylactic acid (trade name: Lacti 1000, manufactured by Shimadzu Corporation). , And a degree of polymerization of about 500,
5 parts by weight of a polyvinyl alcohol-based polymer having a hydroxyl group ratio (saponification ratio) of about 98% were mixed and melt-kneaded at a cylinder temperature of 210 ° C. and a die temperature of 200 ° C. using a twin screw extruder in the same direction. And tried to extrude it into a sheet shape while removing water from the vent hole. However, the surface of the sheet was not smooth, and the load on the motor of the extruder gradually began to increase. When this polyvinyl alcohol-based polymer is used, it has been difficult to extrude and produce a good sheet.

Example 3: Sheet No. Production of 3 A polylactic acid (trade name: Lacti 1000, manufactured by Shimadzu Corporation) was mixed with 20% by weight of a polyhydroxybutyrate / valerate copolymer (trade name: Biopol D600G, manufactured by Monsanto) in 80% by weight, and further mixed. Polymerization degree about 170
0, 5 parts by weight of a polyvinyl alcohol-based polymer having a hydroxyl group ratio (saponification ratio) of about 80% are mixed and melt-kneaded at a cylinder temperature of 210 ° C. and a die temperature of 200 ° C. using a co-directional twin-screw extruder. The sheet was extruded into a sheet shape while removing water from a vent hole by a pump, and was extruded on a cooling roll having a surface temperature of 45 ° C. to obtain a sheet having a thickness of 100 μm.

Comparative Example 4: Sheet No. Preparation of 8 Polyhydroxybutyrate / valerate copolymer (trade name: Biopol D600G, manufactured by Monsanto Co., Tg =
(-10 ° C.) Polyhydroxybutyrate / valerate copolymer (trade name: Biopol D3) instead of 20% by weight
10G, manufactured by Monsanto Co., Tg = 10 ° C.) 20% by weight
A sheet having a thickness of 100 μm was obtained in the same manner as in Example 3 except for mixing.

Comparative Example 5: Sheet No. 9 Production of polylactic acid (trade name: Lacti 1000, manufactured by Shimadzu Corporation) and polybutylene succinate / adipate copolymer (trade name: Bionore # 3001, manufactured by Showa Kogyo Co., Ltd.)
0% by weight, cylinder temperature 200
The mixture was extruded into a strand shape while being melted and kneaded by a twin screw extruder at 200 ° C. and a die temperature of 200 ° C., and cut into chips by a rotary blade. After the chips were sufficiently dried to remove water, the cylinder temperature was 200 ° C. and the die temperature was 20 ° C.
Using a T-die extruder at 0 ° C, the sheet was extruded onto a cooling roll having a surface temperature of 55 ° C to obtain a sheet having a thickness of 100 µm.

Comparative Example 6: Sheet No. Manufacture of 10 Polylactic acid (trade name: Lacti 1000, manufactured by Shimadzu Corporation) and polybutylene succinate / adipate copolymer (trade name: Bionole # 3001, manufactured by Showa Polymer)
0% by weight and further mixed with an ethylene-vinyl alcohol copolymer (trade name: EVAL EP-H101,
10 parts by weight of Kuraray Co., Ltd.) were mixed, melt-kneaded at a cylinder temperature of 200 ° C. and a die temperature of 200 ° C. by a twin screw extruder in the same direction, extruded into a strand shape, and cut into chips by a rotary blade. After sufficiently drying the chips to remove water, the chips were extruded onto a cooling roll having a surface temperature of 55 ° C. using a T-die extruder at a cylinder temperature of 200 ° C. and a die temperature of 200 ° C. to obtain a sheet having a thickness of 100 μm. Was.

Example 4: Sheet No. Production of 4 70% by weight of polylactic acid (trade name: Lacti 1000, manufactured by Shimadzu Corporation) was mixed with 30% by weight of polybutylene succinate / adipate copolymer (trade name: Bionore # 3001, manufactured by Showa Polymer Co., Ltd.). And rutile titanium dioxide (trade name: TR-700, Fuji Titanium Industry Co., Ltd.)
10 parts by weight) and 10 parts by weight of a polyvinyl alcohol-based polymer having a degree of polymerization of about 1700 and a ratio of hydroxyl groups (saponification rate) of about 80%.
The mixture is melt-kneaded at a die temperature of 200 ° C. by a twin screw extruder in the same direction, extruded into a sheet shape while removing water from a vent hole by a vacuum pump, and extruded onto a cooling roll having a surface temperature of 35 ° C. to form a sheet having a thickness of 560 μm. Obtained.

Comparative Example 7: Sheet No. Preparation of 11 20% by weight of polybutylene succinate / adipate copolymer (trade name: Bionore # 3001, manufactured by Showa Polymer Co., Ltd.) was mixed with 80% by weight of polylactic acid (trade name: Lacti 1000, manufactured by Shimadzu Corporation). And rutile titanium dioxide (trade name: TR-700, Fuji Titanium Industry Co., Ltd.)
Was extruded into a strand shape while being melt-kneaded with a coaxial twin screw extruder at a cylinder temperature of 210 ° C. and a die temperature of 200 ° C., and cut into chips by a rotary blade. After sufficiently drying the chips to remove water, the chips were extruded onto a cooling roll having a surface temperature of 50 ° C. using a T-die extruder at a cylinder temperature of 210 ° C. and a die temperature of 200 ° C. to obtain a sheet having a thickness of 560 μm. Was.

Comparative Example 8: Sheet No. Preparation of 12 A polybutylene succinate / adipate copolymer (trade name: Bionore # 3001, manufactured by Showa Polymer Co., Ltd.) was mixed with 80 wt% of polylactic acid (trade name: Lacti 1000, manufactured by Shimadzu Corporation) at 20 wt%. , And a degree of polymerization of about 120,
20 parts by weight of a polyvinyl alcohol-based polymer having a hydroxyl group ratio (saponification ratio) of about 80% was mixed, and a cylinder temperature of 21% was used.
The mixture is melt-kneaded at 0 ° C. and a die temperature of 200 ° C. by a twin screw extruder in the same direction, extruded into a sheet shape while removing water from vent holes by a vacuum pump, and extruded onto a cooling roll having a surface temperature of 35 ° C., and has a thickness of 100 μm. Sheet was obtained.

Embodiment 5: Card No. Forming (Lamination) 1 The sheet of Example 4 (Sheet No. 4) was used as the core layer, and the sheet was cut into a width of 30 cm and a length of 40 cm. Was printed. An adhesive was used as needed. A toluene / MEK solution in which 100 parts by weight of a copolymerized polyester hot-melt adhesive Byron 300 (manufactured by Toyobo Co., Ltd.) and 8 parts by weight of a polyisocyanate compound Desmodur L-75 (manufactured by Bayer) are mixed on both sides of the core layer. Was applied and dried sufficiently at room temperature to evaporate the solvent, and the thickness of the adhesive was adjusted to about 3 μm.

Example 1 (Sheet N)
o. Using the sheet of 1), a core sheet printed with two 30 cm × 40 cm oversheets was sandwiched, and one sheet on each side was sandwiched between two chromium-plated steel sheets. Then, under an atmosphere sucked by vacuum, hot pressing was performed under the conditions shown in Table 3 and at a pressure of 10 kg / cm ² . The hot press time is 10 minutes for the constant temperature time, and the total time for starting and ending the temperature rise is 30 to 40 minutes.

Comparative Example 9: Card No. Molding (lamination) of Comparative Example 7 (sheet No. 11) was used as the core layer, and Example 3 (sheet No.
A card was prepared in the same manner as in Example 5 except that the sheet of 3) was used.

Comparative Example 10: Card No. Molding (lamination) of Comparative Example 3 The sheet of Comparative Example 7 (Sheet No. 11) was used as the core layer, and Comparative Example 5 (Sheet No. 1) was used as the oversheet.
A card was prepared in the same manner as in Example 5 except that the sheet of 1) was used.

[0076]

[Table 1]

[0077]

[Table 2]

* 1: Biaxially oriented sheet * 2: The sheet has no rigidity * 3: Cannot be melt-extruded * 4: Poor biodegradability * 5: Poor fixability of printed patterns and characters. Fruits 1 to 4 in Table 2 mean Examples 1 to 4, and ratios 1 to 8 mean Comparative Examples 1 to 8.

[0079]

[Table 3]

[0093] In Table 3, the actual 5 means Example 5, and the ratio 9
10 means Comparative Examples 9 and 10. The sheets of Examples 1 to 4 are within the scope of the present invention and have good impact resistance and heat resistance, but also have excellent fixing of printed designs and characters.

Comparative Examples 5 and 7 do not contain a polyvinyl alcohol-based polymer and are not excellent in printability. In Comparative Example 1, the blending number of the polyvinyl alcohol-based polymer is larger than the range of the invention, the stiffness as a sheet is low, and the heat resistance is so low that it cannot withstand aging after printing. In Comparative Example 2, the ratio of hydroxyl groups in the polyvinyl alcohol-based polymer was low, and the printability was poor. Comparative Example 3
In this case, the proportion of hydroxyl groups was too high, the crystallization of the polyvinyl alcohol-based polymer was too high, and extrusion was impossible because the polymer was not completely melted in the extruder.

In Comparative Example 4, although the printability was excellent, the glass transition point of the mixed aliphatic polyester exceeded 0 ° C., resulting in poor impact resistance. In Comparative Example 6, the printability was excellent but the biodegradability was poor. In Comparative Example 8,
The degree of polymerization of the polyvinyl alcohol-based polymer is low, and it is easy to exude from the sheet. Therefore, print design
Poor fixability of characters.

Next, in the case of making a card, in Comparative Example 10 in which the same sheet as in Comparative Example 5 was attached to the over layer and evaluated, it was possible to make a card, and the printed portion of the core layer was sharp. As can be seen, printing on the over layer resulted in poor fixability of the ink. In Example 5 and Comparative Example 9, although the sharpness of the printed portion of the core layer was slightly inferior, it was found that the ink printed on the over layer had excellent fixability, impact resistance, and heat resistance.

[0084]

As a result of the present invention, when a biodegradable sheet or a card base material is used, a biodegradable plastic sheet having excellent printability on its surface and excellent impact strength and heat resistance. As well as the card.

Claims (2)

[Claims] 1. A polylactic acid-based polymer having a glass transition point of 0 ° C.
The following other aliphatic polyesters are 100/0 to 60/4
0, a polyvinyl alcohol-based polymer represented by the following general formula (1) was added in an amount of 1 to 100 parts by weight of the mixture.
A decomposable recording sheet characterized by being mixed in an amount of up to 30 parts by weight. Embedded image [In the above general formula (1), m and n are m + n ≧ 150
It is a positive number satisfying 97 ≧ 100 m / (m + n) ≧ 40. ] 2. A degradable recording card, wherein the sheet according to claim 1 is laminated on one or both sides of a core layer serving as a support.