JP2003334913A - Method for manufacturing biodegradable card - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a biodegradable card excellent in cutting properties as a card, embossed character stamping property, pull strength, impact strength, and heat resistance. <P>SOLUTION: A core layer containing a polylactic acid and a biodegradable aliphatic polyester with a glass transition temperature (Tg) of 0°C or lower and an over layer containing a polylactic acid and a biodegradable aliphatic polyester with a glass transition temperature(Tg) of 0°C or lower are thermally pressed or fusion-bonded to laminate the overcoat layers to both surfaces of the core layer not only to laminate both overlayers to both surfaces of the core layer but also to crystallize the core layer and the overcoat layer to set not only the degree of crystallization of the core layer after thermal press or thermal fusion bonding to 0.8 or more but also the degree of crystallization of the over layer to 0.9 or more. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic card that decomposes in a natural environment. In particular, it relates to a biodegradable card having a multilayer structure, which is excellent in flexibility and heat resistance.

[0002]

2. Description of the Related Art Conventionally, various types of plastic cards have been used in a wide range, but most of them are used for a relatively short time and burned or discarded. On the other hand, from the viewpoint of environmental problems, it is not always easy to incinerate or discard, and various cards made of biodegradable plastic have been proposed. For example, in Japanese Patent Application Laid-Open No. 8-267968, a multilayer structure having over layers on both surfaces of a core layer is made of biodegradable plastic, and polylactic acid or lactic acid and oxycarboxylic acid are used as the over layer in order to meet the requirement of transparency. It has been proposed to use an acid copolymer as a main component.

[0003]

However, although such a proposal certainly meets the requirement of transparency, there are actually the following problems. An unstretched sheet of polylactic acid is very fragile, and when it is cut into a certain size with a cutting machine, it will be cracked or broken, and it will be difficult to finish it neatly. This also applies to the laminated sheets. In addition, embossed characters may be mechanically inserted after making a card, but at this time also, there is a risk of causing cracks and cracks. Moreover, the amorphous sheet of polylactic acid has a glass transition temperature of about 60 ° C., and at a temperature exceeding this temperature, the rigidity (elastic modulus) sharply decreases, which is not practical. Further, JP-A-8-267968 proposes to use a biaxially stretched sheet of polylactic acid. Certainly, it is effective in that it is possible to improve the brittleness while maintaining the transparency of polylactic acid, but in this state, distortion remains, so that there is a problem that the sheet shrinks due to the heat applied in the steps such as printing and lamination.

[0004]

The first object of the present invention is to:
40 to 90% by weight of polylactic acid and glass transition temperature (T
g) biodegradable aliphatic polyester 60 having a temperature of 0 ° C. or less
40 to 0% by weight of biodegradable aliphatic polyester having a polylactic acid content of 60 to 100% by weight and a glass transition temperature (Tg) of 0 ° C. or lower on both surfaces of a core layer containing a composition consisting of 10 to 10% by weight as a main component. % Of the crystallization melting heat (ΔHm) of the polylactic acid portion when the temperature of the core layer and the overlayer is raised, That the crystallinity {(ΔHm-ΔHc) / ΔHm} calculated from the heat of crystallization (ΔHc) of the polylactic acid portion generated by crystallization is 0.8 or more and 0.9 or more, respectively. It is in a characteristic biodegradable card.

Secondly, 40-90% by weight of polylactic acid having a L-lactic acid: D-lactic acid ratio of 100: 0 to 94: 6 or 6:94 to 0: 100 and a glass transition temperature (T
g) biodegradable aliphatic polyester 60 having a temperature of 0 ° C. or less
The heat of crystallization fusion of the polylactic acid portion (ΔHm) when the temperature is increased and the heat of crystallization of the polylactic acid portion (ΔHm) generated by crystallization during the temperature increase (ΔHm)
Hc) and crystallinity {(ΔHm-ΔHc)
/ ΔHm} is 0.8 or more, in the core layer of the biodegradable card.

A third gist is 60 to 100% by weight of polylactic acid having a ratio of L-lactic acid: D-lactic acid of 100: 0 to 94: 6 or 6:94 to 0: 100 and a glass transition temperature (T).
g) biodegradable aliphatic polyester 40 having a temperature of 0 ° C. or lower
The amount of heat of crystallization of the polylactic acid portion when heated (ΔHm) and the amount of heat of crystallization of the polylactic acid portion that is generated by crystallization during heating (ΔH)
c) and the crystallinity {(ΔHm-ΔHc) /
ΔHm} is 0.9 or more, in the overlayer of the biodegradable card.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION When selecting polylactic acid which is one of the polymer components of the composition constituting the core layer or the overlayer in the present invention, its crystallinity becomes important. For example, when amorphous polylactic acid exceeds the glass transition temperature, its rigidity sharply decreases and begins to flow. Therefore, when it is used as a card, its heat resistance is insufficient, which is a drawback in use. On the other hand, fully crystallized polylactic acid retains its rigidity, although it becomes slightly softer even in a temperature range exceeding the glass transition temperature,
It does not flow. That is, in the biodegradable card of the present invention, it is preferable that the polylactic acid component is crystallized in at least the core layer, and preferably in both the core layer and the overlayer. For that purpose, the polylactic acid is selected to be crystalline. It is important to keep

The crystallinity of polylactic acid varies depending on the type and proportion of lactic acid constituting the polylactic acid. Polylactic acid includes poly-L-lactic acid or a homopolymer of poly-D-lactic acid whose structural unit is only one of L-lactic acid and D-lactic acid, and a structural unit of L-lactic acid.
There are copolymers containing both lactic acid and D-lactic acid. Both homopolymers, poly L-lactic acid and poly D-lactic acid, are crystalline. The copolymer becomes amorphous depending on the ratio of L-lactic acid and D-lactic acid. That is, L in the copolymer
-If the ratio of lactic acid to D-lactic acid is within the range of 94: 6 to 6:94, it is amorphous and does not crystallize even if heat treatment is carried out, or its crystallinity is too low even if crystallized. Does not satisfy the heat resistance. In short, crystalline polylactic acid is obtained when the ratio of L-lactic acid and D-lactic acid in the polymer is within the range of 100: 0 to 94: 6 or 6:94 to 0: 100, and crystallized by heat treatment or the like. The higher the degree of chemical conversion, the higher the heat resistance. However, as described later, the ratio of L-lactic acid and D-lactic acid in the polylactic acid polymer is in the range of 98: 2 to 94: 6 or 6:94 to 2:98 from the viewpoint of sheet bonding. It is preferable to set the inside.

The method for producing polylactic acid is not particularly limited and may be any method such as condensation polymerization method and ring-opening polymerization method. As the monomer, L-lactic acid, D-lactic acid or a mixture thereof may be condensed. Legally also L-lactide, which is a cyclic dimer of lactic acid,
D-lactide, DL-lactide or mixtures thereof are used in the ring-opening polymerization process. Further, for the purpose of increasing the molecular weight, a small amount of a chain extender such as a diisocyanate compound, an epoxy compound or an acid anhydride may be used during the polymerization.

The preferred weight average molecular weight of polylactic acid is 6
If it is too small, it will be difficult to exhibit practical physical properties, and if it is too large, the melt viscosity will increase and the moldability will be poor. The glass transition temperature (Tg) of polylactic acid is 60 ° C.
The melting temperature (Tm) varies depending on the ratio of L-lactic acid and D-lactic acid, the amorphous one has no melting temperature, and the crystalline one is in the range of 100 to 200 ° C.

In the present invention, another one of the polymer components of the composition constituting the core layer or the overlayer is a crystalline aliphatic polyester having a low glass transition temperature (hereinafter simply referred to as "aliphatic polyester"). . This aliphatic polyester is capable of improving the brittleness of polylactic acid and improving impact resistance, and is preferably particularly limited as long as it retains rigidity above the glass transition temperature of 60 ° C. of polylactic acid. Alternatively, two or more kinds may be mixed. Specifically, the glass transition temperature (Tg) is 0 ° C. or lower, preferably −
A biodegradable aliphatic polyester having a temperature of 20 ° C. or lower is used. Above all, in order to maintain rigidity above 60 ° C,
A material having a melting temperature (Tm) of 80 ° C. or higher is selected.

Typical examples of the aliphatic polyester used in the present invention include polyhydroxybutyrate and polyhydroxybutyrate / valerate (copolymer) biosynthesized by microorganisms. In addition, polybutylene succinate (condensation polymer of 1,4-butanediol and succinic acid) chemically synthesized by dehydration condensation polymerization of aliphatic dicarboxylic acid and aliphatic diol, polybutylene succinate /
Examples thereof include adipate (copolymer).

It is known that microbially-produced aliphatic polyesters represented by polyhydroxybutyrate are biosynthesized by acetyl coenzyme A (acetyl CoA) in cells such as Alcaligenes eutrophus. The aliphatic polyester produced is mainly poly-β-hydroxybutyric acid (poly3HB), but in order to improve the practical properties as a plastic, the fermentation process was devised and the valeric acid unit (HV) was copolymerized. There is also poly (3HB-co-3HV). The copolymerization ratio is generally 0 to 40%, and the melting temperature (Tm) in this range is
Is 130 to 165 ° C. Instead of HV, 4HB may be copolymerized or a long-chain hydroxyalkanoate may be copolymerized.

In the chemically synthesized aliphatic polyester represented by polybutylene succinate, the aliphatic diol unit which is one of the structural units is ethylene glycol, propylene glycol, 1,4-butanediol, 1,4. -Selected from cyclohexanedimethanol and the like. The aliphatic dicarboxylic acid unit which is the other structural unit,
It is selected from succinic acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid and the like.

The production method of the above-mentioned aliphatic polyester is not particularly limited and can be synthesized by any method such as polycondensation method and ring-opening polymerization method. As the monomer, each of the above-mentioned diol and dicarboxylic acid can be used. At least one mixture is used in the condensation polymerization method, and at least one mixture of oxiranes and acid anhydrides which are ring-closing compounds of diol and dicarboxylic acid is used in the ring-opening polymerization method. As oxiranes which are ring-closing compounds,
Examples thereof include ethylene oxide, propylene oxide, and tetrahydrofuran, and examples of the acid anhydride include succinic anhydride and adipic anhydride. During the polymerization, by selecting the mixing ratio of the monomers,
It is possible to obtain a crystalline aliphatic polyester having an arbitrary composition. Further, for the purpose of increasing the molecular weight, a small amount of a chain extender such as a diisocyanate compound, an epoxy compound or an acid anhydride may be used during the polymerization.

The glass transition temperature (Tg) and melting temperature (Tm) of the above-mentioned aliphatic polyester differ depending on the composition and the molecular weight, but are -60 to 0 ° C and 9 respectively.
It is about 0 to 170 ° C. Further, the preferable weight average molecular weight of the aliphatic polyester is 50,000 to 1,000,000, and if it is too small, the melt tension is low, and the sheet when melt extruded is difficult to take out, and if it is too large, the melt viscosity is too high. Inferior in sex.

Therefore, the main component composition of the core layer of the card of the present invention is 40 to 90% by weight of polylactic acid, preferably 50.
-80 wt%, particularly preferably 60-70 wt% and aliphatic polyester 60-10 wt%, preferably 50
-20% by weight, particularly preferably 40-30% by weight. When the content of the aliphatic polyester is less than 10% by weight, the impact resistance is insufficiently improved and the embossed characters cannot be stamped. Moreover, when the sheet is cut, cracks or breaks easily occur. When the amount of the aliphatic polyester exceeds 60% by weight, the rigidity is remarkably insufficient and it is difficult to handle as compared with the current PVC card.

The main component composition of the overlayer of the card of the present invention comprises 60 to 100% by weight of polylactic acid and 40 to 0% by weight of aliphatic polyester. When the polylactic acid content is less than 60% by weight, the transparency is insufficient. Usually the overlayer is
Since a material having higher transparency than the core layer is required, a composition having a higher proportion of polylactic acid than the core layer is selected. When the sheet to be the over layer is a stretched sheet, 100% polylactic acid is preferable from the viewpoint of transparency and the like as described later. In the case of an unstretched sheet, preferably 70 to 90% by weight of polylactic acid and 30 to 1 of aliphatic polyester are used.
0% by weight, particularly preferably polylactic acid 70-
80% by weight and 30-20% by weight of aliphatic polyester
Those consisting of are preferred. It is true that the higher the proportion of the aliphatic polyester is, the better the transparency is, in consideration of embossed characters and sheet cutting. Therefore, an appropriate composition is selected within the above range depending on the use of the card.

A method for forming a sheet to be a core layer or an overlayer of the card of the present invention is a method in which the above-mentioned polylactic acid and aliphatic polyester having a predetermined composition, together with other polymers or additive components as necessary, are used in an extruder. Alternatively, the method may be used in which a sheet is directly prepared by feeding the sheet into a sheet, or a method in which the sheet is produced by once extruding into a strand shape and cutting it into pellets, and then again feeding the sheet into an extruder. Actually, in consideration of the decrease in molecular weight due to decomposition in the extruder, the polylactic acid and the aliphatic polyester are sufficiently dried in advance to remove water, and then melted in the extruder. The melt extrusion temperature is appropriately selected in consideration of the melting temperature and composition of the polymer in the composition, but is usually selected from the range of 100 to 250 ° C.

The polymer composition melt-formed into a sheet is preferably contacted with a rotating casting drum and cooled. Although the temperature of the casting drum varies depending on the kind and composition of the polymer in the composition, usually 60 ° C. or lower is suitable. At higher temperatures, the polymer sticks to the casting drum and cannot be removed. In particular, when the sheet is stretched, it is preferable to make the polylactic acid portion substantially amorphous by quenching so that crystallization of the polylactic acid portion is promoted and spherulites do not develop.

In the present invention, the sheet to be the core layer or the over layer obtained as described above is cut into a suitable size for obtaining a predetermined card, if necessary, and then laminated to form a laminate. And For example, 1 or 2
A biodegradable card having over layers on both surfaces of the core layer is obtained by a hot pressing method in which a sheet to be a core layer is sandwiched between two sheets to be an over layer and heated under pressure. The pressing temperature is appropriately selected depending on the melting temperature of polylactic acid or aliphatic polyester, and the pressing pressure is 5 to 4
0 kg / cm ² is used. In addition, the advantage of using two sheets that should be the core layer is to avoid complicated double-sided printing,
It is possible to adopt the same configuration by combining two non-printed surfaces printed individually.

However, it is preferable to fuse at a temperature of 150 ° C. or lower in order to deal with the conventional PVC card manufacturing equipment. In that case, the ratio of L-lactic acid and D-lactic acid of the polylactic acid which is the main component is set so that the bonding can be performed at a temperature of 150 ° C. or less. In particular,
In either one of the core layer and the over layer,
The ratio of L-lactic acid and D-lactic acid in the crystalline polylactic acid was 98:
It is selected from the range of 2 to 94: 6 or 6:94 to 2:98. On the other hand, when either L-lactic acid or D-lactic acid exceeds 98%, the crystallinity of polylactic acid becomes high and the fusion temperature becomes high. In that case, even if the layers are hot-pressed at a temperature of 150 ° C. or lower, sufficient fusion strength between the sheets is not obtained, and the sheets are peeled off with a slight force. That is, in laminating the sheets, it is important to fuse the over layer and the core layer, and to fuse the two core layers to each other when two or more core layers are used. Therefore, the over layer is
If the sheet is made of polylactic acid in which the ratio of L-lactic acid and D-lactic acid is within the range of 98: 2 to 94: 6 or 6:94 to 2:98, the core layer is L-lactic acid and D-lactic acid. The fusion strength is improved even if either of the sheets is made of polylactic acid exceeding 98%. Of course, the opposite is also effective. However, when using a plurality of core layers to be laminated, it is preferable to use a sheet in which the ratio of L-lactic acid and D-lactic acid within the specific range is set as both core layers.

Other methods for laminating the sheets include a method of heat-sealing and a method of laminating with an adhesive.
In the former case, the melting temperature of the sheets or a temperature slightly higher than the melting temperature is raised to fuse both sheets. However, if the melting temperature is significantly exceeded, the sheet cannot retain its shape and begins to flow, so be careful. Since this method can promote crystallization of the polylactic acid portion at the same time as fusion,
This is effective when the polylactic acid portion of the sheet has low crystallinity. The latter method using an adhesive (most often a hot melt type) can be applied at a relatively low temperature, so it is effective when applying a stretched / heat-fixed sheet in which polylactic acid is sufficiently crystallized. is there.

On the other hand, in the case of the hot press method, the hot press is usually heated from room temperature to the bonding temperature, then kept at a constant temperature for several minutes and then cooled.
At this time, the amorphous polylactic acid sheet is crystallized at the same time as the fusion of the sheets occurs during the temperature rise. Here, with a sheet containing essentially no polylactic acid or aliphatic polyester that does not crystallize, flow starts and a good card cannot be obtained. Next, when the temperature is further raised, a part of the crystal melts out near the melting point and can be completely fused. However, it should be noted that if the melting point is significantly exceeded, the sheet cannot maintain its shape and begins to flow. In any case, in this step, the polylactic acid portion of the sheet is crystallized. This is an advantage of using crystalline polylactic acid,
This is a method of obtaining a card having heat resistance suitable for practical use.

In the present invention, it is extremely important that the core layer and the over layer thus formed by bonding are sufficiently crystallized in order to obtain a card having heat resistance suitable for practical use. This is also an advantage of using crystalline polylactic acid. In the biodegradable card of the present invention, the polylactic acid portion of the core layer has a crystallinity of 0.8 or more, and the polylactic acid portion of the overlayer has a crystallinity of 0.9 or more. It is necessary.

In the present specification, the crystallinity of the polylactic acid moiety present in the core layer, the overlayer or the sheet forming them is defined by the following formula. Crystallinity = (ΔHm−ΔHc) / ΔHm In the formula, ΔHm is the heat of crystallization fusion of the polylactic acid part when the temperature is raised, and ΔHc is the crystal of the polylactic acid part generated by the crystallization during the temperature rise. It is the amount of heat of chemical conversion. Further, all of these calories are measured using a differential scanning calorimeter (DSC) according to JIS K7122. Specifically, a 10 mg sample collected from the core layer, the overlayer, or the material forming them is heated at a heating rate of 10 ° C./min to draw a DSC curve, and the melting temperature (T
mH) from the endothermic peak area of melting that appears in the vicinity of ΔHm (J
/ G) and the crystallization temperature (T
From the exothermic peak area of crystallization that appeared near c), ΔHc
(J / g) is measured, and these measured values are substituted into the above formula to calculate the crystallinity. The closer the crystallinity is to 1.0, the higher the crystallization, and the closer to 0, the amorphous state. The guideline for crystallization is 0.8 or more. In addition, the melting point does not appear for those which are not essentially crystallized.

Therefore, it is important to set the conditions of the laminating step or the stretching / heat setting step so that the biodegradable card as a product can achieve the above predetermined crystallinity. In particular, the stretched and heat-fixed polylactic acid sheet is to be crystallized while maintaining strength, improvement of brittleness, and transparency as described in JP-A-7-2027041 and JP-A-7-205278. Therefore, it is suitable for forming an overlayer of a biodegradable card, but it is important to set heat-setting conditions as described later.

In the stretching step, the sheet is stretched between two rolls having different peripheral speeds, and / or the sheet is gripped with a clip using a tenter while stretching the row intervals of the clip rows. The tenter stretching is performed. In the case of biaxial stretching, either simultaneous or sequential stretching method may be used. The stretching ratio of the sheet is, for example, 1. in the longitudinal (longitudinal) direction and the transverse (width) direction, respectively.
The stretching temperature is 5 to 5 times, preferably 2 to 4 times.
It is appropriately selected within a range of 0 to 90 ° C, preferably 55 to 80 ° C. The tenter stretching method is advantageous because the sheet can be stretched in the tenter and then heat set in the tenter.

However, the polylactic acid sheet to be the overlayer has a degree of plane orientation (ΔP) of 3.0 × 10 ⁻³ or more, preferably 5. before the lamination with the core layer. 0x1
It is preferable to control the crystallinity of the polylactic acid portion {(ΔHm-ΔHc) / ΔHm} to 0 ^-3 to 30 × 10 ^-3 and 0.9 or more. That is, in the polylactic acid oriented sheet, the brittleness that the material originally has,
It can be improved by increasing the degree of plane orientation (ΔP), and the thermal dimensional stability that decreases as the degree of plane orientation increases can be improved by increasing the degree of crystallinity.

The degree of plane orientation (ΔP) represents the degree of orientation in the plane direction with respect to the thickness direction of the sheet, and is usually calculated according to the following formula by measuring the refractive index in the directions of three orthogonal axes. ΔP = ((γ + β) / 2) −α (α <β <
γ) where γ and β are refractive indices of two orthogonal axes parallel to the sheet surface,
α is the refractive index in the sheet thickness direction.

The degree of plane orientation (ΔP) depends on the crystallinity and the crystal orientation, but largely depends on the molecular orientation in the sheet plane. Therefore, an increase in ΔP means an increase in the molecular orientation in the plane of the sheet, particularly in the sheet flow direction and / or the direction orthogonal thereto, and therefore increases the strength of the sheet and improves the brittleness. . Surface orientation degree (△
As a method for increasing P), in addition to any known sheet stretching method, a molecular orientation method using an electric field or a magnetic field can be adopted.

However, the stretched sheet having an increased degree of plane orientation (ΔP) also has a large heat shrinkability and warps the finished card. The heat setting for controlling (suppressing) the heat shrinkability of the stretched sheet is performed by heating the sheet to a temperature as high as possible for 3 seconds or more in a range in which the sheet does not melt. The temperature range is (Tm-50) to Tm (° C) based on the melting temperature Tm of polylactic acid, preferably (Tm).
-30) to Tm (° C). The crystallinity of the polylactic acid portion of the sheet is preferably set to 0.9 or more by heat setting.

The card of the present invention may be provided with a printing layer, a thermosensitive recording layer, etc., if necessary. In that case, it is preferably provided on the surface or between the layers of the core layer or the over layer. When a magnetic recording layer or the like is provided, it is preferable to form a magnetic stripe or embed an IC on the surface of the over layer by an appropriate method.

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

[0035]

EXAMPLES The present invention will be described in detail below with reference to examples. The measurements and evaluations shown in the examples were carried out under the following conditions except the conditions described in the text.

(1) Glass Transition Temperature (Tg) and Melting Temperature (Tm) It was measured based on JIS K7121 using a differential scanning calorimeter DSC-7 manufactured by Perkin Elmer. Sample 1
0 mg was set, the temperature was raised to 200 ° C. at a heating rate of 10 ° C./min, and the temperature was maintained for 2 minutes to completely melt the sample. After that, the DS when the temperature is lowered at a rate of 10 ° C / min
The melting endothermic peak temperature appearing on the C curve is the melting temperature (T
m). The temperature was further lowered, and once lowered to −60 ° C. and held for 2 minutes, the temperature was raised again at 10 ° C./min, and the intermediate value of the transition curve was taken as the glass transition temperature (Tg). Liquid nitrogen was used as the cooling medium for the measurement at 0 ° C or lower.

(2) Degree of plane orientation (ΔP) It was calculated using the refractive indices (α, β, γ) in the directions of the three orthogonal axes, which were measured using an Abbe refractometer.

(3) Crystallinity {(ΔHm-ΔHc) / Δ
Hm} The heat of fusion (Δ) measured using the same device as in (1) above.
Hm) and heat of crystallization (ΔHc) were used for calculation.

(4) Ten cutting cards were stacked and cut with a cutting machine. Those with good results are marked with a circle, and if there is a problem, the details are described.

(5) Evaluation of embossed characters The embossed characters were embossed on the card using a manual type embossed character embossing machine (DC830 type) manufactured by Nippon Data Card Co., Ltd. Those with good results are marked with a circle,
If there is a problem, the details are described.

(6) Credit Card Standard with Magnetic Stripe (JIS X6310) Based on this standard, the following 6 items were evaluated.

Tensile strength: Standard 47.1 N / mm ²
that's all. The measured value is described.

Impact strength: When a card is placed on a solid horizontal plate and a 500 g steel ball is dropped onto it from a height of 30 cm, the card should not crack or crack.
Those with good results are marked with a circle, and if there is a problem, the details are described.

Flexible temperature: Standard 52 ° C. or higher. The measured value is described.

Heat resistance: No change on the surface of the card when the card is immersed in warm water at 60 ° C. for 5 minutes. Furthermore, the same evaluation was performed in hot water at 80 ° C. This test is also an index of the heat resistance of the card. Those with good results are marked with a circle, and if there is a problem, the details are described.

Adhesiveness: temperature 40 ° C., relative humidity 90
% When a pressure of 4.9 kPa is applied and stored for 48 hours in an atmosphere, there should be no sticking between the cards. Those with good results are indicated by ◯, and x indicates sticking between the cards.

Moisture resistance: temperature 40 ° C., relative humidity 90
% Appearance does not change even if kept in the atmosphere for 48 hours. Those with good results are marked with a circle,
If there is a problem, the details are described.

Interlaminar peeling strength: Identification card standard J
It was evaluated by the test method according to IS X 6301. Laminated sheet after laminated hot pressing is 10 mm width x 100 m
Cut into m strips, make a cut in each layer (over layer and core layer or core layer when two core layers are made together), peel off by hand, and chuck both ends to a tensile tester. The peel strength was calculated. 40m between chucks
m, and the pulling speed was set to 100 mm / min. The maximum tensile strength at that time was calculated. This was defined as peel strength per 1 cm width. The standard is 6 N / cm or more.
The measured value and the result that applies to the standard are marked with a circle.

(7) Comprehensive Evaluation The practicality of the card was evaluated on the basis of the following criteria by combining the measurement and evaluation results of the above (4) to (6) in three levels. ◯: Excellent Δ: Practical range ×: Poor practicability

Experimental Example 1 [Formation of a sheet to be a core layer] Polylactic acid having a weight average molecular weight of 200,000 obtained by ring-opening polymerization of L-lactic acid lactide (D-lactic acid content of 1% or less) ( Product Name: Lacty 10
00, manufactured by Shimadzu Corporation, and 15 parts by weight of rutile type titanium dioxide (trade name: TR-700, manufactured by Fuji Titanium Industry Co., Ltd.), and mixed at a cylinder temperature of 210 ° C. and a die temperature of 200 ° C. in the same direction. While being melt-kneaded with a twin-screw extruder, it was extruded into a strand shape and cut into chips with a rotary blade. After sufficiently drying this chip to remove water, the temperature of the cylinder is 210 ° C and the temperature of the die is 200 ° C.
It was extruded onto a cooling roll having a surface temperature of 58 ° C. using a die extruder to obtain a sheet having a thickness of 560 μm.

[Formation of Sheet to be Overlayer] A transparent sheet having a thickness of 100 μm and made of polylactic acid was obtained in the same manner as the sheet to be the core layer except that titanium dioxide was not mixed.

[Card Molding] An image is printed on the surface of the above-mentioned sheet to be the core layer by using a silk printer, and then sandwiched between the above-mentioned two sheets to be the over-layer, and the press temperature is 180 ° C. After heating at a pressure of 10 kg / cm ² , 10
After hot pressing for 3 minutes, a card having a three-layer structure of over layer / core layer / over layer was obtained. The polylactic acid of the over layer and the core layer is crystallized in this hot pressing step,
The biodegradable card has substantially improved heat resistance. The evaluation results of the obtained cards are also shown in Table 1.

Experimental Example 2 [Formation of sheet to be used as core layer] Polylactic acid having a weight average molecular weight of 200,000 obtained by ring-opening polymerization of lactide of L-lactic acid (D-lactic acid content of 1% or less) ( Product Name: Lacty 10
00, manufactured by Shimadzu Corporation, and polybutylene succinate / adipate copolymer (trade name: Bionole # 30).
01, Showa Highpolymer Co., Ltd.) in a weight ratio of 85:15
15 parts by weight of rutile type titanium dioxide (trade name: TR-700, manufactured by Fuji Titanium Industry Co., Ltd.) was mixed with 100 parts by weight of the biodegradable resin thus blended. Cylinder temperature 210 ℃, Die temperature 2
It was extruded into a strand shape while being melt-kneaded with a twin-screw extruder in the same direction at 00 ° C., and cut into chips with a rotary blade. After sufficiently drying the chips to remove moisture, the chips were extruded at a cylinder temperature of 210 ° C. and a die temperature of 200 ° C. onto a cooling roll having a surface temperature of 58 ° C. to obtain a sheet having a thickness of 560 μm. It was

[Formation of Sheet to be Overlayer] Polybutylene succinate / adipate copolymer (Bionole # 3001) with polylactic acid (Lacty 1000)
Except that it was blended so that the weight ratio of was 90:10.
Similar to the above-mentioned core layer sheet, thickness 100μ
A transparent sheet of m was obtained.

[Molding of Card] A biodegradable card was obtained in the same manner as in Experimental Example 1 except that the above two sheets were used. The evaluation results of the obtained cards are also shown in Table 1.
It was shown to.

Experimental Examples 3 and 4 The weight ratio of Bionole # 3001 to Lacty 1000 was 70: 3 for the sheet to be the core layer.
A biodegradable card was obtained in the same manner as in Experimental Example 2 except that the sheets to be overlayers were 0 and 30:70, and 80 and 20 and 70:30, respectively. . Table 1 also shows the evaluation results of the obtained cards.

Experimental Examples 5 and 6 Two kinds of polyhydroxybutyrate / valilate copolymers (trade names: Biopol D300G, Biopol D600) were used instead of the bionole # 3001 of Experimental Example 3.
A biodegradable card was obtained in exactly the same manner as in Experimental Example 3 except that G and Monsanto Co., Ltd. were both used.
Table 1 also shows the evaluation results of the obtained cards.

Experimental Examples 7 and 8 Instead of the Lacty 1000 of Experimental Example 3, polylactic acid containing about 5% D-lactic acid component (trade name: EcoPLA20) was used.
00D, sold by Cargill Japan Co., Ltd., and polylactic acid containing about 10% of D-lactic acid component and not crystallized even when heat-treated, and the heat pressing temperature at the time of bonding is 160 each. A biodegradable card was obtained in exactly the same manner as in Experimental Example 3 except that the temperature was set to 0 ° C and 110 ° C. Table 1 also shows the evaluation results of the obtained cards.

Experimental Example 9 [Formation of Sheet to be Core Layer] In the same manner as in Experimental Example 3, a sheet to be a core layer was obtained.

[Formation of Sheet to be Overlayer] According to the method of forming a sheet to be an overlayer in Experimental Example 1, a transparent sheet of polylactic acid having a thickness of about 700 μm was obtained.
Next, this sheet was preheated with a metal roll and then stretched 2.5 times in the machine direction between the rolls having a peripheral speed difference while being heated with an infrared heater. Subsequently, it was transversely stretched 3.0 times with a tenter, and subsequently heat-treated in the tenter to give a thickness of 100 μm.
A stretched and heat-set sheet of m was obtained. The conditions for stretching and heat treatment were as follows.

[0061] Longitudinal stretching: Stretching temperature 75 ° C Draw ratio 2.5 times Lateral stretching: Stretching temperature 72 ° C Draw ratio 3.0 times Heat treatment: Heat treatment temperature 130 ℃ Heat treatment time 20 seconds

[Card molding] An image is printed on the surface of the above-mentioned sheet to be the core layer by using a silk printing machine, and further, both surfaces of the copolymerized polyester hot melt adhesive Byron 300 (Toyobo ( Co., Ltd.) 100 parts by weight of polyisocyanate compound Desmodur L-75
8 parts by weight of toluene / MEK solution (manufactured by Bayer Co., Ltd.) is applied and dried sufficiently at room temperature to volatilize the solvent and adjust the adhesive to a thickness of about 3 μm. It is sandwiched between two stretched / heat-set sheets to be the above-mentioned overlayer, and is hot-pressed at a pressing temperature of 110 ° C. and a pressure of 5 kg / cm ² for 5 minutes after the temperature rise to form an overlayer / core layer / overlayer. A layered biodegradable card was obtained. The polylactic acid in the core layer undergoes crystallization in this hot pressing step, and becomes a card with substantially improved heat resistance. The evaluation results of the obtained cards are also shown in Table 1.

Experimental Example 10 A card was manufactured in exactly the same manner as in Experimental Example 9 except that the heat treatment temperature at the time of producing the polylactic acid stretched / heat-fixed sheet to be the overlayer was 100 ° C. The obtained card is extremely warped and is unsuitable as a card.

Experimental Example 11 However, except that the stretching ratio at the time of producing the polylactic acid stretched / heat-fixed sheet to be the overlayer was 1.5 times in both length and width,
A biodegradable card was obtained in the same manner as in Experimental Example 9. Table 1 also shows the evaluation results of the obtained cards.

Experimental Example 12 [Formation of sheet to be used as core layer] A sheet to be used as a core layer was obtained in the same manner as in Experimental Example 9 except that EcoPLA2000D was used instead of Lacty 1000.

[Formation of Sheet to be Overlayer] In Experimental Example 9, EcoPLA was used instead of Lacty 1000.
Using 2000D, stretching and heat treatment were performed under the following conditions to obtain a sheet to be an overlayer.

[0067] Longitudinal stretching: Stretching temperature 75 ° C Draw ratio 3.0 times Lateral stretching: Stretching temperature 75 ° C Draw ratio 3.5 times Heat treatment: Heat treatment temperature 135 ℃ Heat treatment time 20 seconds

[Card Molding] A biodegradable card was obtained in the same manner as in Experimental Example 9. Table 1 also shows the evaluation results of the obtained cards.

Experimental Example 13 In the same manner as in Experimental Example 12, except that the adhesive coating in Experimental Example 9 was not applied and the temperature was changed to 155 ° C. and the pressure was 15 kg / cm ² when laminating by hot pressing. I got a degradable card. Table 1 also shows the evaluation results of the obtained cards.

Experimental Example 14 A polyester hot melt type adhesive Byron 300 (manufactured by Toyobo Co., Ltd.) was used at the time of hot pressing and bonding, except that the temperature was 90 ° C. and the pressure was 5 kg / cm ^2. A biodegradable card was obtained in the same manner as in Experimental Example 3.
Table 1 also shows the evaluation results of the obtained cards.

[0071]

[Table 1]

[0072]

[Table 2]

As shown in the above table, Experimental Example 1 is a result with only the resin component polylactic acid, and it is understood that there are problems in cutting property, embossed character marking and impact strength.

Experimental Examples 2 to 8 and 14 are examples in which polylactic acid was mixed with another aliphatic polyester to form a core layer and an overlayer, and cards were produced. Of these, Experimental Example 4 in which the content of the aliphatic polyester is out of the range of the present invention is difficult in terms of tensile strength and heat resistance, while the glass transition temperature (Tg) of the aliphatic polyester is less than that of the present invention. In Experimental Example 5, which is out of the range, there are problems in cutting property and impact strength. Furthermore, in Experimental Example 8 using polylactic acid which is essentially uncrystallizable, and in Experimental Example 14 where polylactic acid which is inherently crystallizable was used but not sufficiently crystallized, the tensile strength was low and the heat resistance was further improved. Is low and not practical. Experimental Example 14
Then, there is a problem in adhesiveness.

Experimental Examples 9 to 13 are examples in which a stretched sheet of polylactic acid was used for the overlayer. The characteristic of using these crystalline polylactic acid stretched / heat-set sheets for the over layer is that the softening temperature as a card can be increased and the tensile strength can be improved. Among them, in Experimental Example 10 in which the heat treatment temperature is low and the crystallinity is out of the range of the present invention, the warpage when formed into a card is large and it is not suitable for practical use. Also, in Experimental Example 11, although it is within the scope of claim 1 and can be put to practical use, the surface orientation degree is low (claim 3 not reached), cutting performance, embossed character engraving and impact strength are slightly improved. Inferior. On the other hand, in Experimental Example 13 in which bonding was performed without using an adhesive, within the scope of the present invention, sufficient heat treatment was performed, and the polylactic acid used was near the melting temperature (slightly above). Warp is suppressed and heat fusion can be performed by hot pressing.

Experimental Examples 15 to 22 [Formation of a sheet to be an overlayer] A weight average molecular weight of 200,000 obtained by ring-opening polymerization of L-lactic acid lactide (D-lactic acid content of about 0.8%). Polybutylene succinate / adipate copolymer (trade name: Bionole # 3001, manufactured by Showa Highpolymer Co., Ltd.) was added to 30% by weight of the polylactic acid of, and the biaxial screw was in the same direction at a die temperature of 200 ° C. While extruding into a strand shape while melt-kneading with an extruder, it was cut into chips with a rotary blade. After sufficiently drying the chips to remove moisture, a surface temperature of 58 was obtained by using a T-die extruder at a cylinder temperature of 210 ° C. and a die temperature of 200 ° C.
It was extruded on a cooling roll at 0 ° C. to obtain a sheet having a thickness of 100 μm. This overlayer sheet is indicated by the symbol OA.

In the same manner, polylactic acid having D-lactic acid contents of about 5.5% and about 10% (weight average molecular weights of about 180,000 and 150,000, respectively).
Polybutylene succinate / adipate copolymer (trade name: Bionole # 3001, Showa Highpolymer Co., Ltd.)
(Manufactured) were compounded in the proportions shown in Table 2, and a sheet having a thickness of 100 μm was obtained by the same method as described above. Each of these over layer sheets is represented by the symbols shown in Table 2. However, only the sheet OC * does not contain the biodegradable aliphatic polyester.

[Formation of Sheet to be Core Layer] Polylactic acid having a weight average molecular weight of 200,000 (trade name) obtained by ring-opening polymerization of lactide of L-lactic acid (D-lactic acid content rate of 0.8%) : Rakuti 1000, manufactured by Shimadzu Corporation, was mixed with polybutylene succinate / adipate copolymer (trade name: Bionole # 3001, manufactured by Showa Highpolymer Co., Ltd.) in an amount of 30% by weight. Blended biodegradable resin 1
Rutile titanium dioxide (trade name: T
12 parts by weight of R-700 and Fuji Titanium Industry Co., Ltd. are mixed and extruded into a strand shape while melt-kneading with a twin-screw extruder in the same direction at a cylinder temperature of 210 ° C. and a die temperature of 200 ° C., and a rotary blade is used. It was cut into chips. After the chips were sufficiently dried to remove water, the chips were extruded onto a cooling roll having a surface temperature of 58 ° C. with a cylinder temperature of 210 ° C. and a die temperature of 200 ° C. to a thickness of 2 ° C.
Sheets of 80 μm and 560 μm were obtained. The sheets for both core layers are denoted by the symbols CA and CA.

In a similar manner, polylactic acid having a D-lactic acid content of about 2.5% and about 5.5% (weight average molecular weights of about 200,000 and 18%, respectively).
10,000), polybutylene succinate / adipate copolymer (trade name: Bionole # 3001, Showa Highpolymer Co., Ltd.)
Or a polyhydroxybutyrate / valilate copolymer (trade name: Biopol D600G, manufactured by Monsanto Co., Ltd.) in the proportions shown in Table 2, and the same thickness as above. A 280 μm sheet was obtained. These core layer sheets are represented by the symbols shown in Table 2. However, only the sheet CC * does not contain the biodegradable aliphatic polyester.

[0080]

[Table 3]

In the table, the unit of the numerical value with no particular description of unit is% by weight. [Card molding] Of the above core layers, a 560 μm-thick sheet is printed on both sides, a 280 μm-thick sheet is printed on one side, and an image is printed using a silk printing machine. in the sheet of 280μm thickness Cascade facing the unprinted faces, respectively, sandwiching the over layer two shown in Table 3 above, Table 3 at a pressure 10 kg / cm ²
The temperature is increased to the lamination temperature shown in the above, and after the temperature is increased, heat pressing is performed for 10 minutes to form 3 layers or 4 layers of over layer / core layer / over layer or over layer / core layer / core layer / over layer.
A layered biodegradable card was obtained. Table 3 shows the laminated structure of each of the obtained cards and the evaluation results.

[0082]

[Table 4]

From the results of Table 3, in Experimental Examples 15 to 19,
It has excellent impact strength, heat resistance, and adhesiveness, and exceeds the standard for peeling strength between the overlayer and core layer, and also peeling strength between core layers when two core layers are configured. I understand. On the other hand, in Experimental Example 20, the peel strength between the core layers is particularly low and the practicality is low. This is because it is between the thick core layers where it is difficult to transfer heat, and because the crystallinity is originally high, it was crystallized before sufficient adhesion was obtained. In Experimental Example 21, the impact resistance is low because the aliphatic polyester is not included, and in Experimental Example 22, the overlayer includes polylactic acid having a D-lactic acid ratio that is outside the scope of the present invention. for,
There was a problem in terms of heat resistance and tackiness.

[0084]

Industrial Applicability According to the present invention, it is possible to provide a biodegradable card which is excellent in cutting property when formed into a card, embossed character marking, tensile strength, impact strength, heat resistance and the like.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2C005 HA21 JA08 KA02 KA03 LA03                 4F100 AK41A AK41B AK41C BA03                       BA06 BA10B BA10C BA16                       EJ172 EJ422 GB90 JA05A                       JA11A JA11B JA11C JJ03                       JK02 JK10 JL00 YY00A                       YY00B YY00C

Claims (5)

[Claims] 1. A sheet to be a core layer containing polylactic acid and a biodegradable aliphatic polyester having a glass transition temperature (Tg) of 0 ° C. or lower, and a sheet to be an overlayer containing polylactic acid. , By hot pressing or heat fusion, the sheet to be the core layer is bonded to both surfaces of the sheet to be the core layer, and the sheet to be the core layer and the sheet to be the overlayer. The crystallization of the polylactic acid portion is promoted, and the crystallinity of the polylactic acid portion of the core layer and the polylactic acid portion of the over layer formed by laminating the sheet to be the core layer and the sheet to be the over layer are respectively set to 0. A method for producing a biodegradable card, which is 8 or more and 0.9 or more. 2. The method for producing a biodegradable card according to claim 1, wherein the sheet to be the core layer and the sheet to be the overlayer have low crystallinity. 3. A ratio of L-lactic acid and D-lactic acid in the polylactic acid contained in the sheet to be the core layer, and / or L in the polylactic acid contained in the sheet to be the overlayer. -The ratio of lactic acid to D-lactic acid is 98: 2 to 94: 6.
Alternatively, the method for producing a biodegradable card according to claim 1 or 2, wherein the ratio is 6:94 to 2:98. 4. The sheet to be the core layer has a polylactic acid content of 40 to 90% by weight and a glass transition temperature (Tg) of 0 ° C.
The main component of the composition is 60 to 10% by weight of the following biodegradable aliphatic polyester.
The biodegradation according to any one of claims 1 to 3, which comprises as a main component a composition comprising 0% by weight and 40 to 0% by weight of a biodegradable aliphatic polyester having a glass transition temperature (Tg) of 0 ° C or less. Of manufacturing sex card. 5. The method for producing a biodegradable card according to claim 1, wherein the sheet to be the overlayer is a non-stretched sheet.