JP2009012481A - Polylactic acid-based laminated sheet for heat bending molding - Google Patents

Abstract

The present invention provides a sheet having sufficient impact resistance, heat resistance, and heat folding formability without particularly increasing the sheet thickness, and a tough heat bending molded body that can withstand distribution and storage from this sheet. Objective.
The main component is a stretched and heat-set A layer comprising a polylactic acid polymer as a main component and a polylactic acid polymer having a melting point lower than the melting point of the polylactic acid polymer constituting the A layer. In the laminated sheet having the B layer, the melting point of the A layer is Tma (° C.), and the melting point of the B layer is Tmb (° C.).
180> Tma ≧ 154 and Tma−Tmb> 10 (1)
The opening angle before heat resistance is 1 to 13 °, and the opening angle after heating is 5 to 19 °.
[Selection figure] None

Description

  The present invention relates to a polylactic acid-based laminated sheet for heat bending molding.

  Blister processed products, box-shaped folded products, shell-shaped packaging cases, etc. that are widely used for display and packaging of various products are thermoforming methods such as vacuum forming, pressure forming, and heat folding forming of a predetermined synthetic resin sheet In general, it is manufactured by molding. As this blister processed product, box-shaped processed product, and shell-shaped packaging case, a transparent one is preferred so that the product inside can be seen through the package. From such points, sheets of polyvinyl chloride, polyethylene terephthalate, polystyrene, etc. are frequently used as material sheets for blister processed products and the like that are actually used.

  Transparent folding cases such as desk calendars are also molded by the same thermoforming method, and as the material sheet, sheets of polyethylene terephthalate, polypropylene, polystyrene, etc. are frequently used from the viewpoint of transparency, moldability, heat resistance, etc. ing.

  However, since these materials are chemically and biologically stable, they remain and accumulate with little degradation even if left in a natural environment. These are not only scattered in the natural environment and contaminating the living environment of animals and plants, but also remain almost undecomposed when landfilled as garbage, thereby shortening the life of the landfill.

  On the other hand, from the viewpoint of environmental protection, research and development of biodegradable materials have been actively conducted in recent years. One of the biodegradable materials that has been attracting attention is polylactic acid. Since polylactic acid is biodegradable, it naturally hydrolyzes in soil and water and becomes a harmless degradation product by microorganisms. Moreover, since the amount of combustion heat is small, even if incineration is performed, the furnace is not damaged. Furthermore, since the starting material is derived from a plant, it has features such as being able to escape from exhausted petroleum resources.

However, polylactic acid has low heat resistance, and when storing and transporting polylactic acid sheets and molded articles thereof, the storage, transported trucks, and the interior of the ship often reach high temperatures in summer. Problems such as deformation and fusion may occur.
Furthermore, polylactic acid has brittleness and is difficult to use as it is in the form of a sheet.

  On the other hand, Patent Document 1 discloses that when a polylactic acid sheet is stretched biaxially and given a predetermined orientation, a blister sheet and a molded product excellent in transparency and impact resistance can be obtained.

JP-A-8-73628

  However, if an attempt is made to obtain impact strength in a shape necessary for the blister container, the necessary sheet thickness increases, resulting in a problem that the pressure during molding becomes excessive.

  In addition, a sliding blister generally used in blister packaging is bent around the molding part 3 in order to mount a mount, but the stretched polylactic acid-based sheet has an elastic modulus. It is high and has the property of returning to its original shape when bent. Furthermore, even if the heat bending method of bending with heat is performed, the bending cannot be fixed unless it is brought close to the melting point, and there is a drawback that it returns to its original state. In addition, the heat resistance of the bent portion is inferior.

  Accordingly, the present invention provides a sheet having sufficient impact resistance, heat resistance, and heat folding formability without particularly increasing the sheet thickness, and a tough heat bending molded body that can withstand distribution and storage from this sheet. The purpose is to do.

The present invention relates to a laminated sheet having a polylactic acid-based polymer as a main component, an A layer stretched and heat-set, and a B-layer mainly composed of a polylactic acid-based polymer. (C), and when the B layer has a melting point lower than the melting point of the polylactic acid polymer constituting the A layer, the melting point is Tmb (° C.), or the B layer has no melting point. When a lactic acid-based polymer is a main component, the polylactic acid-based polylactic acid for bending by bending has a relationship of the following formula (1) or (2) when its glass transition point is Tmb (° C.) The above-mentioned problems have been solved by using a laminated sheet.
180> Tma ≧ 154 and Tma−Tmb> 10 (1)
180> Tma ≧ 154 and Tma− (Tgb + 70)> 10 (2)

  Since a layer mainly composed of a specific stretched and heat-set polylactic acid polymer is used, the resulting laminated sheet has sufficient heat resistance and a sheet thickness of about 0.03 to 2.0 mm. Even a laminated sheet having a thickness of 10% has sufficient impact resistance. Furthermore, since the melting point or glass transition point of each layer is within a predetermined range, it has sufficient heat bending formability.

  Moreover, since such a laminated sheet is used, a tough heat-folded molded body that can withstand distribution and storage can be obtained.

  Since the polylactic acid-based laminated sheet for heat folding according to the present invention has a layer mainly composed of a specific stretched and heat-set polylactic acid-based polymer, the obtained laminated sheet has sufficient heat resistance. In addition, a laminated sheet having a thickness of about 0.03 to 2.0 mm has sufficient impact resistance. Furthermore, since the melting point of each layer is set within a predetermined range, it has sufficient heat folding formability.

  In addition, such a polylactic acid-based laminated sheet for heat folding molding is excellent in transparency, impact resistance, and folding moldability, and since such a laminated sheet is used, it has a folding portion such as a slide blister, a calendar holder, A tough heat-folded molded body that can withstand distribution and storage can be obtained.

Hereinafter, embodiments of the present invention will be described in detail.
The polylactic acid-based laminated sheet for heat folding according to the present invention comprises a polylactic acid-based polymer as a main component, a stretched and heat-fixed layer (hereinafter referred to as “A layer”), and a polylactic acid-based polymer. Is a laminated sheet having a layer (hereinafter, referred to as “B layer”).

  The polylactic acid-based polymer that is the main component of the A layer and the B layer is a homopolymer whose structural unit is L-lactic acid or D-lactic acid, that is, poly (L-lactic acid) or poly (D-lactic acid), Examples thereof include copolymers having structural units of both L-lactic acid and D-lactic acid, that is, poly (DL-lactic acid) and mixtures thereof.

  As a method for polymerizing the polylactic acid-based polymer, any known method such as a condensation polymerization method or a ring-opening polymerization method can be employed. For example, in the condensation polymerization method, a polylactic acid polymer having an arbitrary composition can be obtained by directly dehydrating condensation polymerization of L-lactic acid, D-lactic acid, or a mixture thereof.

  In the ring-opening polymerization method, a polylactic acid-based polymer can be obtained using lactide, which is a cyclic dimer of lactic acid, using a catalyst appropriately selected while using a polymerization regulator or the like as necessary. Lactide includes L-lactide, which is a dimer of L-lactic acid, D-lactide, which is a dimer of D-lactic acid, and DL-lactide composed of L-lactic acid and D-lactic acid. By mixing and polymerizing, a polylactic acid polymer having an arbitrary composition and crystallinity can be obtained.

  Furthermore, a small amount of copolymerization component can be added as required for improving heat resistance, etc., and non-aliphatic diols such as non-aliphatic dicarboxylic acids such as terephthalic acid and ethylene oxide adducts of bisphenol A are used. You can also.

  Furthermore, 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 can be used.

  The polylactic acid polymer may be a copolymer with another hydroxycarboxylic acid unit such as α-hydroxycarboxylic acid, or a copolymer with an aliphatic diol / aliphatic dicarboxylic acid. .

  Examples of the other hydroxy-carboxylic acid units include optical isomers of lactic acid (D-lactic acid for L-lactic acid, L-lactic acid for D-lactic acid), glycolic acid, 3-hydroxybutyric acid, 4- Bifunctional aliphatic hydroxy-carboxylic acids such as hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy3,3-dimethylbutyric acid, 2-hydroxy3-methylbutyric acid, 2-methyllactic acid, 2-hydroxycaproic acid, etc. Examples include lactones such as caprolactone, butyrolactone, and valerolactone.

  Examples of the aliphatic diol copolymerized with the polylactic acid polymer include ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol and the like. Examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, suberic acid, sebacic acid, and dodecanedioic acid.

  The preferred range of the weight average molecular weight of the polylactic acid polymer used in the present invention is 60,000 to 700,000, more preferably 65,000 to 400,000, particularly preferably 70,000 to 300,000. is there. When the weight average molecular weight is less than 60,000, the physical properties such as mechanical properties and heat resistance may be inferior, and when the weight average molecular weight is more than 700,000, the melt viscosity may be too high and the molding processability may be inferior.

  An aliphatic polyester can be added to the polylactic acid polymer used in the present invention for the purpose of improving impact resistance. As the aliphatic polyester, an aliphatic polyester having a glass transition temperature (Tg) of 0 ° C. or lower and a melting point (Tm) of 60 ° C. or higher as a main component (hereinafter referred to as “specific aliphatic polyester”). Is preferably used. When Tg exceeds 0 ° C, the impact resistance improving effect of the sheet tends to be insufficient, and transparency tends to deteriorate due to spherulite crystallization of the aliphatic polyester. If Tm is less than 60 ° C., the heat resistance tends to be inferior.

  Examples of the specific aliphatic polyester include aliphatic polyesters obtained by condensing aliphatic diols and aliphatic dicarboxylic acids, aliphatic polyesters obtained by ring-opening polymerization of cyclic lactones, synthetic aliphatic polyesters, biosynthesized in bacterial cells. And aliphatic polyesters.

  The aliphatic polyester obtained by condensing the aliphatic diol and the aliphatic dicarboxylic acid is an aliphatic diol such as ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, succinic acid, adipic acid, One or more aliphatic dicarboxylic acids such as suberic acid, sebacic acid, and dodecanedioic acid are selected and subjected to condensation polymerization. Furthermore, a desired polymer can be obtained by performing a chain linking reaction with an isocyanate compound or the like as necessary.

  The aliphatic polyester obtained by ring-opening polymerization of the ring-opening lactone is polymerized by selecting one or more cyclic monomers such as ε-caprolactone, δ-valerolactone, and β-methyl-δ-valerolactone.

  Examples of the synthetic aliphatic polyester include a copolymer of a cyclic acid anhydride and an oxirane, such as a copolymer of succinic anhydride and ethylene oxide, propylene oxide, or the like.

  As the aliphatic polyester biosynthesized in the microbial cells, aliphatic polyesters biosynthesized by acetylcoenteam A (acetyl CoA) in the microbial cells such as Alkali geneus eutrophus are known. As this aliphatic polyester, poly-β-hydroxybutyric acid (poly 3HB) can be mainly cited. In order to improve practicality as a plastic, valeric acid unit (HV) is copolymerized with poly 3HB, It is industrially advantageous to use (3HB-co-3HV). The copolymerization ratio of HV to poly-3HB is generally 0-40%. Further, a long-chain hydroxyalkanoate may be copolymerized.

  Specific examples of the specific aliphatic polyester include polybutylene succinate, polybutylene succinate adipate, polybutylene adipate terephthalate, polycaprolactone, polyglycolic acid, polyester carbonate, polyhydroxybutyrate and polyhydroxyvalylate. Examples thereof include a polymer, a copolymer of polyhydroxybutyrate and polyhydroxyhexanoate, and the like. Only one kind of the above-mentioned specific aliphatic polyester may be used, or a plurality thereof may be mixed and used.

  When the specific aliphatic polyester is mixed with the polylactic acid polymer, the content of the specific aliphatic polyester is 0.1 to 20 parts by weight with respect to 100 parts by weight of the polylactic acid polymer. Is preferable, and 0.1-10 weight part is preferable. If the amount is less than 0.1 part by weight, the impact resistance may not be sufficiently obtained. If the amount exceeds 20 parts by weight, the transparency may not be sufficient.

  In addition, in the present invention, it is possible to prevent the end material from being regenerated and mixed in the manufacturing process as long as the performance is not impaired.

  The A layer is a layer composed of a sheet mainly composed of a polylactic acid polymer and stretched and heat-set.

  The stretching may be uniaxial stretching or biaxial stretching, but biaxial stretching is preferable because a highly oriented sheet is obtained (hereinafter, the stretched sheet is referred to as “stretched oriented sheet”). Called). The index of orientation at this time is the plane orientation ΔP, which is preferably 3.0 × 10 −3 or more, and preferably 5.0 × 10 −3 to 20 × 10 −3. If it is smaller than 3.0 × 10 −3, the heat resistance tends to be inferior.

  In order to satisfy the above-mentioned plane orientation ΔP, it is preferable to stretch at least 1.5 times, preferably 2 to 5 times in at least one uniaxial direction. The stretch-oriented layer enhances the impact resistance against dropping of the molded body and impact when applied to other articles.

  Following the stretching, heat setting is performed. As a result, a heat-set stretched sheet is obtained. The heat setting refers to a process of fixing a sheet and applying heat to remove distortion and the like, and by doing this, the heat resistance of the obtained sheet is improved.

  The degree of heat setting is such that {(ΔHm−ΔHc) / ΔHm} is 0 when the total crystallization melting heat amount ΔHm when the sheet is heated and the crystallization heat amount ΔHc generated by crystallization during the temperature increase. The heat setting temperature and the processing time are selected so as to be 85 or more. If {(ΔHm−ΔHc) / ΔHm} is less than 0.85, it tends to be difficult to impart sufficient heat resistance to the sheet. The upper limit of the degree of plane orientation is actually about 30 × 10 −3. If it is larger than this, the continuity of stretching cannot be maintained.

  The heat setting temperature is not less than the glass transition temperature (Tga) of the resin composition constituting the A layer and not more than the melting temperature (Tma), preferably not less than Tga + 20 ° C., not more than Tma-10 ° C., more preferably Tga + 40 ° C. As mentioned above, it carries out at Tma-20 degrees C or less.

  Furthermore, the heat setting time is appropriately determined so as to have the above characteristics, but is usually selected from 5 seconds to 60 seconds. If it is shorter than 5 seconds, the heat treatment effect is insufficient, and even if it exceeds 60 seconds, the increase in the effect tends not to be recognized.

  The shrinkage ratio at 90 ° C. for 30 minutes in the machine direction and the transverse direction of the biaxially oriented sheet that is the A layer that has been biaxially stretched and then heat-set is preferably 10% or less, and more preferably 5% or less. If it exceeds 10%, heat shrinkage tends to occur when the sheet is formed. The lower limit of the shrinkage rate is 0% because it is most preferable not to shrink.

  The DL content ratio of the lactic acid component in the polylactic acid polymer used in the A layer is preferably 3% or less (or 97% or more) as the content ratio of either D-lactic acid or L-lactic acid. In particular, when the DL content is 0.5% or more and 3% or less (or 97% or more and 99.5% or less), the melting point of the A layer is equal to the melting point of the A layer defined by the following formula (1). Within the range, the A layer is excellent in impact resistance and heat resistance, and appropriate workability can be obtained.

  The B layer is a layer composed of a sheet mainly composed of an amorphous polylactic acid polymer having a melting point lower than the melting point of the polylactic acid polymer constituting the A layer or not having a melting point. is there. This B layer may or may not be stretched or heat set.

  The DL content ratio of the lactic acid component in the polylactic acid polymer used for the B layer is preferably D-lactic acid / L-lactic acid = 3/97 to 97/3, more preferably 4/96 to 96/4. . If it deviates from this range, it tends to be difficult to impart formability, and at the same time, the heat bendability tends to be insufficient.

  Further, as the polylactic acid polymer constituting the B layer, a mixed resin obtained by mixing an aliphatic polyester other than the above polylactic acid, in particular a specific aliphatic polyester, with polylactic acid whose structural unit is lactic acid. It is preferable to use it. When this mixed resin is used, it is possible to exhibit the feature that the folded appearance is improved due to the effect of mitigating cracks in the heat folded portion.

When the polylactic acid polymer constituting the B layer has a melting point, the melting point is preferably lower than the melting point of the polylactic acid polymer constituting the A layer. The melting point of the resin constituting the resin and the melting point of the resin constituting the B layer preferably have the relationship of the following formula (1).
180> Tma ≧ 154 and Tma−Tmb> 10 (1)
In the above formula (1), the melting point of the A layer is represented by Tma (° C.), and the melting point of the B layer is represented by Tmb (° C.).

  That is, the melting point Tma of the A layer is preferably 154 ° C. or higher and lower than 180 ° C., and preferably 160 ° C. or higher and lower than 180 ° C. When this temperature range is satisfied, the A layer is excellent in impact resistance and heat resistance, and appropriate workability can be obtained. On the other hand, when the temperature is lower than 154 ° C., sufficient heat resistance at the bent portion tends to be difficult to obtain. On the other hand, when it is 180 ° C. or higher, the bending workability tends to be inferior.

  Further, the difference between the melting point Tma of the A layer and the melting point Tmb of the B layer, Tma−Tmb, is preferably 10 ° C. or more, and preferably 15 ° C. or more. When the difference is less than 10 ° C., it becomes difficult to impart formability to the laminated sheet according to the present invention, and the heat bendability tends to deteriorate. By the way, the upper limit of Tma-Tmb is preferably 60 ° C., and preferably 55 ° C. When it is higher than 60 ° C., the heat resistance of the bent portion tends to be inferior. In addition, melting | fusing point can be measured by the method shown in the Example mentioned later.

  The method for obtaining the difference in melting point between the resins of the A layer and B layer is not particularly limited. For example, it can be obtained by adjusting the mixing ratio of D-lactic acid and L-lactic acid in the lactic acid component contained in the polylactic acid polymer. It can also be obtained by adding a plasticizer to the B layer.

When the polylactic acid polymer constituting the B layer does not have a melting point, the melting point of the resin constituting the A layer and the glass transition point of the resin constituting the B layer have the relationship of the following formula (2): It is good to have.
180> Tma ≧ 154 and Tma− (Tgb + 70)> 10 (2)
In the above formula (2), the melting point of the A layer is represented by Tma (° C.), and the glass transition point of the B layer is represented by Tgb (° C.).

  The range of the melting point Tma of the A layer is preferably 154 ° C. or higher and lower than 180 ° C., and preferably 160 ° C. or higher and lower than 180 ° C. for the same reason as described above.

  Further, the difference between the melting point Tma of the A layer and the glass transition point Tgb + 70 ° C. of the B layer, Tma− (Tgb + 70) is preferably 10 ° C. or more, and preferably 15 ° C. or more. When the difference is less than 10 ° C., it becomes difficult to impart formability to the laminated sheet according to the present invention, and the heat bendability tends to deteriorate. In addition, melting | fusing point and glass transition point can be measured by the method shown in the Example mentioned later.

  The method for obtaining the difference between the melting point of the A layer and the glass transition point of the B layer + 70 ° C. is not particularly limited. For example, it can be obtained by adjusting the mixing ratio of D-lactic acid and L-lactic acid in the lactic acid component contained in the polylactic acid polymer. It can also be obtained by adding a plasticizer to the B layer.

  By laminating the A layer and the B layer, the polylactic acid-based laminated sheet for heat bending molding according to the present invention is manufactured. Next, this lamination method will be described.

Examples of the lamination method include the following two methods. In any case, at least one layer is stretched and heat-set under tension.
(1) One layer and the other layer are coextruded and then stretched.
(2) After extruding each layer, bonding is performed. etc

  Regarding the method (1), first, a polylactic acid polymer forming each layer, an aliphatic polyester other than the above polylactic acid, in particular, a mixed resin in which a specific aliphatic polyester is mixed, inorganic particles, and the like Are respectively supplied to an extrusion apparatus for coextrusion lamination, and the resin composition is prepared in this apparatus. In addition, the resin composition may be extruded into a strand shape by another extruder in advance to produce pellets. In any case, a decrease in molecular weight due to decomposition must be taken into consideration, but the latter is preferred for uniform mixing.

  For the purpose of adjusting various physical properties, a heat stabilizer, a light stabilizer, a light absorber, a plasticizer, an inorganic filler, a colorant, a pigment, and the like can be added to the resin composition. At this time, the addition amount is adjusted in consideration of the required transparency of the application.

  The supplied resin is sufficiently dried to remove moisture, and then melted with an extruder. Changes in melting point due to composition ratio of L-lactic acid and D-lactic acid in polylactic acid polymer, melting point of aliphatic polyester other than polylactic acid, mixing ratio of polylactic acid polymer and aliphatic polyester other than polylactic acid, etc. Then, the melt extrusion temperature is appropriately selected. In practice, a temperature range from the melting point of the polylactic acid polymer to the same melting point + 100 ° C. is usually selected.

  Next, it laminates using 2 or 3 or more multi-manifolds or feed blocks, and it extrudes from a slit-shaped die as a melt-laminated sheet of 2 or more layers. At that time, the thickness of each layer can be set by adjusting the flow rate of the polymer with a quantitative feeder such as a gear pump installed in the melt line.

  Next, the molten laminated sheet extruded from the die is rapidly cooled and solidified on a rotary cooling drum at a temperature equal to or lower than the glass transition temperature (Tg) of the polylactic acid polymer to obtain a substantially amorphous unoriented laminated sheet. . If the temperature of the rotary cooling drum is equal to or higher than the glass transition temperature, crystallization of the laminated sheet proceeds and subsequent stretching becomes difficult, or the thickness accuracy of the laminated sheet is deteriorated in the stretching process. In this case, for the purpose of improving the smoothness and thickness unevenness of the sheet, it is preferable to improve the adhesion between the laminated sheet and the rotary cooling drum. In this invention, the electrostatic application adhesion method and / or the liquid application adhesion The method is preferably used.

  The laminated sheet thus obtained cannot provide sufficient impact strength as it is. For this reason, it is necessary to have sufficient orientation. Specifically, it is preferable to obtain an oriented stretched orientation sheet by biaxial stretching. The index of orientation of the sheet on the A layer side at this time is preferably 3.0 × 10 −3 or more and preferably 5.0 × 10 −3 or more in terms of the plane orientation ΔP. The upper limit of the degree of plane orientation is actually about 30 × 10 −3. If it is larger than this, the continuity of stretching cannot be maintained. In order to achieve this, a stretching temperature of 50 to 100 ° C., a stretching ratio of 1.5 to 5 times and a stretching speed of 100% / min to 10,000% / min are common in at least one axial direction. It is determined as appropriate.

  The stretch-oriented sheet is subjected to heat treatment while being fixed after stretching. Thereby, the heat-fixed stretched orientation sheet is obtained. By heat fixing, sheet deformation at the time of heat bending can be prevented, and further, heat resistance of the bent product can be imparted.

  Next, the above method (2), so-called extrusion lamination will be described. Specifically, a biaxially stretched and oriented sheet is pasted together with one layer and a molten sheet extruded from the die as the other layer with a rotating cooling drum and a silicon lining roll, and a glass transition temperature. Quickly solidify below. Thus, one layer is crystal-oriented and the other layer is a low crystalline laminated sheet.

  The layer structure of the polylactic acid-based laminated sheet for heat folding molding is not particularly limited as long as it is two or more, but has at least three layers, of which the A layer constitutes both outer layers, and the B layer has It is preferable to constitute at least one of the layers sandwiched between the outer layers. When the A layer constitutes both outer layers, sufficient impact resistance and heat resistance can be imparted to the obtained polylactic acid-based laminated sheet for heat folding molding. Further, by forming at least one of the layers sandwiched between the two outer layers with the B layer, sufficient moldability and heat bendability can be imparted.

  Although the transparency of the polylactic acid-based laminated sheet for heat bending molding varies depending on the application, it is usually preferably 20% or less, more preferably 10% or less in terms of haze value. In particular, in the case of a blister container that covers the entire surface of the product or a calendar holder that covers the printed surface, 10% or less is preferable, and 8% or less is more preferable.

  The total thickness of the polylactic acid-based laminated sheet for heat bending molding is determined in consideration of impact resistance, workability, etc. according to the use, but is preferably in the range of 0.03 to 2.0 mm, 0.1 to 1.0 mm is more preferable. If it is 0.03 mm or less, the required strength cannot be obtained, and if it is 2.0 mm or more, there is a tendency that a long time is required for heating during processing or the processing pressure becomes excessive.

  The thickness of the A layer in the polylactic acid-based laminated sheet for heat bending molding, in particular, the A layer on the side to be heated, which will be described later, is preferably 0.01 to 0.5 mm, and 0.01 to 0.2 mm. More preferred. If it is less than 0.01 mm, melting marks at the time of hot folding molding are likely to occur. On the other hand, when the thickness is 0.5 mm or more, the bending heat resistance is inferior, and when the heat bent portion is heated after molding, the bent portion tends to open.

  Moreover, it is preferable that the thickness of the B layer in the polylactic acid-based laminated sheet for heat bending molding is thicker than the thickness of the A layer. If the thickness is smaller than the thickness of the A layer, the heat bendability tends to deteriorate. Further, the thickness of the B layer is preferably 1.0 mm or less, more preferably 0.5 mm or less, and if it is thicker than 1.0 mm, cracks tend to occur during bending.

  For example, when a slide blister is produced as a polylactic acid-based heat-folded molded body obtained by the method described later using the polylactic acid-based laminated sheet for heat-folding, depending on the weight and size of the stored item, the stored item However, for lightweight accessories such as headphones, remote controllers, etc., since the polylactic acid-based laminated sheet for heat folding molding is not required to have so much impact resistance, the sheet thickness is 0.1 to 0.5 mm. 0.15-0.4 mm is preferable. When the thickness is less than 0.1 mm, the drop impact resistance starts to deteriorate. On the other hand, when the thickness is more than 0.5 mm, it may be difficult to form the unevenness according to the stored item due to the blister design.

  In this case, the thickness of the A layer of the sheet is preferably from 0.01 to 0.25 mm, more preferably from 0.01 to 0.2 mm. If it is thinner than 0.01 mm, melting marks may be produced during thermal bending. On the other hand, if it is thicker than 0.25 mm, the bending heat resistance may deteriorate.

  On the other hand, if the stored item is heavy, such as an electric device main body or a charger, the sheet must have a shock resistance, so the sheet thickness is preferably 0.2 to 1 mm, and 0.25 to 0. 0.5 mm is preferred. When it is thinner than 0.2 mm, the drop impact resistance tends to be inferior. On the other hand, if it is thicker than 1 mm, on the blister design, it tends to be difficult to mold with irregularities according to the stored items.

  Moreover, 0.02-0.5 mm is preferable and, as for the thickness of A layer of the sheet | seat in this case, 0.03-0.3 mm is preferable. If it is thinner than 0.02 mm, the impact resistance tends to be inferior. On the other hand, if it is thicker than 0.5 mm, it tends to be difficult to obtain a molded product that matches the shape of the contents.

Next, a method for producing a polylactic acid-based heat-folded molded body using the above-described polylactic acid-based laminated sheet for heat-folding will be described.
The above-mentioned polylactic acid-based laminated sheet can be formed by using general thermoforming in which the sheet is formed by heating. Specifically, there are a vacuum forming method, a plug assist forming method, a pressure forming method, a male / female forming method, a method of expanding a forming male die after deforming a sheet along the forming male die, and the like. In addition, the shape, size, etc. of the molded product shall be appropriately selected according to the application. Examples of the method for heating the sheet include an infrared heater, a hot plate heater, and hot air. The sheet is preheated to the molding temperature and thermoformed to form various containers such as a blister molded product and a container-shaped molded product.

  In the case of using the above-mentioned polylactic acid-based laminated sheet for heat folding, it is possible to perform heat bending to produce a slide type blister container, a calendar holder and the like among the containers. This thermal bending is a molding method in which a heating jig that can be heated linearly is brought into contact with a linear portion to be bent and then mechanically bent into a linear shape.

  As shown in FIGS. 1 (a) and 1 (b), the slide-type blister container 1 refers to a container having a product storage portion 2 that is thermoformed into the shape of a stored item. In order to hold | maintain the said plate-shaped object, the heat | fever bending shaping | molding part 3 is formed in this edge. Then, a plate-like body (not shown) such as a paperboard or a resin sheet can be slid and fitted on the back side at the acute angle side of the heat folding forming part 3 to store the stored items in the product storage part 2.

  2A and 2B, the calendar holder 4 refers to a container for storing and holding a calendar, and heat bent portions 5 are formed on both side edges thereof. A sheet-like calendar (not shown) is accommodated from the open end 5 where no is formed.

  As a method of forming such a heat-folded molded part, as shown in FIG. 3A, the polylactic acid-based laminated sheet 11 for heat-folded molding can be folded, that is, a heat-folded molded part is formed. As shown in FIG. 3 (b), the heating jig 13 that can be heated in a linear shape such as a heating blade, a heating plate, or an infrared heater is brought into contact with the bending line 12 and heated immediately (within a few seconds). ) A method in which the heating jig 13 is released and mechanically bent into a linear shape, and then the bent portion is cooled while being held by the holding plate 14 as shown in FIG. Can be given. Thereby, the polylactic acid-type heat bending molded object which has a predetermined heat bending shaping | molding part can be obtained.

  The heating jig 13 is brought into contact with the A layer side to perform heating. Thereby, if the heating temperature is equal to or lower than the melting point of the A layer, surface melting marks can be prevented.

  After the above-mentioned heat bending forming, the shape of the heat bending forming part is fixed by cooling (cooling) while keeping the bent state so that the temperature of the heat bending forming part is lower than Tgb. This cooling is completed within 10 seconds. When the heat bent part is exposed to a temperature in the vicinity of the Tgb temperature, the heat bent part may open.

  The opening angle of the heat-folded portion immediately after the heat-folding and cooling is preferably 20 ° or less, and preferably 10 ° or less. If the angle exceeds 20 °, the holding property of the mount is lost or the holding portion of the printing sheet is greatly opened, which is not preferable.

  When the obtained polylactic acid-based bent molded body is a slide-type blister container and the above-mentioned heat-folded molded portion is a hairpin shape, the opening angle is indicated by θ1, while the obtained polylactic acid-based bent molded body is As shown in FIG. 4, the opening angle when the fold is bent in a U-shape such as a calendar holder is an opening angle θ2 from the parallel of the upper and lower portions of the U-shape.

  Moreover, it is preferable that the opening angle of the heat-folded portion after 1 hour at 60 ° C. after the heat-folding and cooling is maintained at the same angle as that immediately after the heat-folding and cooling.

  Furthermore, when it is set as a transparent box-shaped case, it shape | molds by sealing in a box shape with an ultrasonic welder etc. after the said process.

  The polylactic acid-based heat-folded molded body obtained in the present invention can be suitably used as a molded body having a heat-folded molded portion such as a slide-type blister container or a calendar holder.

  In addition, the polylactic acid-based laminated sheet for heat folding molding, in which the front and back layers are made of a polylactic acid-based polymer, the outer layer is covered with a polylactic acid-based polymer excellent in food hygiene, so that the produced container shape The molded body can also be used as a container that directly touches food.

The present invention will be described in detail below with reference to examples. First, a measurement method and an evaluation method are shown.
[Weight average molecular weight]
Using a Tosoh Co., Ltd. HLC-8120GPC gel permeation chromatograph apparatus, a calibration curve was prepared with standard polystyrene under the following measurement conditions to determine the weight average molecular weight.
Column used: Shimadzu Shim-Pack series (GPC-801C, GPC-804C, GPC-806C, GPC-8025C, GPC-800CP)
・ Solvent: Chloroform ・ Sample solution concentration: 0.2 wt / vol%
Sample solution injection volume: 200 μl
・ Solvent flow rate: 1.0 ml / min ・ Pump, column, detector temperature: 40 ° C.

[Sheet thickness]
Ten points were measured with a dial gauge SM-1201 manufactured by Teclock Co., Ltd., and the average value was used as the thickness. The unit is mm.

[Measurement of Glass Transition Temperature (Tg) and Melting Point (Tm) of Sheet]
Based on JIS-K-7121, the glass transition temperature (Tg) and melting | fusing point (Tm) resulting from the polylactic acid in a sheet | seat were measured with the temperature increase rate of 10 degree-C / min with the differential scanning calorimetry (DSC). The unit is ° C.

[Measurement of crystallinity]
Based on JIS-K-7121, the heat of fusion (ΔHm) and crystallization caused by the polylactic acid polymer in the biodegradable sheet at a heating rate of 10 ° C./min by differential scanning calorimetry (DSC) The amount of heat (ΔHc) was measured, and the crystallinity of the polylactic acid polymer was calculated from the following formula.
Relative crystallinity (%) = (ΔHm−ΔHc) / ΔHm × 100

[Measurement of haze]
Measurement was performed based on JIS K 7105.
When the haze is less than 10%, the transparency is excellent, and when the haze is 10 to 20%, it is in a practical range, and when it exceeds 20%, it cannot be used.

[Evaluation of impact resistance]
Using a hydro-shot impact tester (model HTM-1) manufactured by Toyo Seiki Co., Ltd., a hitting core having a diameter of 1/2 inch was collided with the laminated sheet at a speed of 3 m / sec at a temperature of 23 ° C. The energy was calculated. If the fracture impact value is 20 kg · mm or more, the impact resistance is excellent, and if it is 10 kg · mm or more and less than 20 kg · mm, it is in the practical range, and if it is less than 10 kg · mm, it cannot be used.

[Evaluation of formability]
Compressed air molding (air pressure: 4kg / cm2, preheating 135 ° C) using a molding die (die temperature 60 ° C) with φ100mm, depth 30mm, and drawing ratio 0.3, and observed the mold forming state of the molded body The evaluation was made in three stages. The evaluation criteria are indicated by “◯” when a molded body having a good shape is formed, “Δ” when it is at a practical level, and “X” when the molded body has a defective shape.
Infrastein heater was used for heating. The temperature immediately before forming the sheet was measured with a far infrared thermometer.

[Evaluation of heat bendability]
A biodegradable sheet is cut into a 100 mm square. As shown in FIG. 3 (a), a folding line 12 is written in the center of the sample with a thin felt pen. Further, the measurement position line 16 is entered at the center of the bend line and at the left and right 10 mm positions.
The heating jig 13 has a square prism shape made of stainless steel with a side of 24 mm, and a cartridge heater that is temperature-controlled is mounted therein. A heat-resistant tape (manufactured by Nitto Denko Corporation: Nitoflon adhesive tape No. 973UL; 0.13 mm thickness × 25 mm width) was attached to the sheet contact portion. As shown in FIG.3 (b), a heating part ridgeline part is pressed along the bending line of a sheet | seat. The time was 5 seconds. The surface temperature of the sheet folding portion was measured with a contact-type thermometer, and was set as the folding temperature Ts (° C.) (conditions were set in advance).

After 1 second, it is bent to the opposite side of the pressing part, and sandwiched between holding plates made of 100 mm (square) x 1 mm (thickness) aluminum plate, as shown in FIG. Cooled for 5 seconds.
The bent sample was cut into a width of 10 mm along the fold line, and the opening amount of the bent portion was measured with a caliper of JISB7507, and the opening angle before heat resistance was obtained from the following formula.
Opening angle (°) = (360 / π) × SIN-1 (opening amount / 20)

  Further, the appearance of the bent portion was evaluated according to the following criteria. The evaluation criteria are indicated by “◯” when no crack-like defect or melting mark is observed, “Δ” when a crack-like defect is recognized, and “X” when a melting mark is recognized.

[Evaluation of heat resistance of bent part]
The folded specimen obtained from the biodegradable sheet is allowed to stand at 60 ° C. for 60 minutes in a hot air oven, and then the opening amount (mm) of the folded portion is measured with a caliper of JISB 7507. Calculated.
Opening angle (°) = (360 / π) × SIN-1 (opening amount / 20)

[Comprehensive evaluation]
The slide blister shown in FIG. 1 and the calendar holder shown in FIG. 2 were thermoformed, and the overall evaluation was judged in consideration of the appearance, the opening angle, and all the above evaluation results. The evaluation criteria were “◯” that can be used satisfactorily for practical use, “Δ” for a practically usable level, and “X” for those that are not suitable for practical use.

[Production example]
(Production Examples 1 and 2)
What added 15 ppm of tin octylates to 100 kg of L-lactide (trade name: PURASORB L) manufactured by Pulac Japan Co., Ltd. was put in a 500 L batch polymerization tank equipped with a stirrer and a heating device. Nitrogen substitution was performed, and polymerization was performed at 185 ° C. and a stirring speed of 100 rpm for 60 minutes. The obtained melt was supplied to a 40 mmφ same-direction twin screw extruder manufactured by Mitsubishi Heavy Industries, Ltd. equipped with three stages of vacuum vents, and extruded in a strand at 200 ° C. while devolatilizing at a vent pressure of 4 torr. Pelletized.
The obtained polylactic acid-based polymer had a weight average molecular weight of 200,000 and an L-form content of 99.5%. The melting point by DSC of the pellet after annealing at 120 ° C. for 4 hours was 178 ° C.
In the same manner, the amount of charged L-lactide and DL-lactide was adjusted to prepare a polylactic acid polymer having a weight average molecular weight of 200,000 and an L-form content of 98.0%. The melting point by DSC of the pellet after annealing at 120 ° C. for 4 hours was 162 ° C.

(Production Examples 3 and 4)
500L batch polymerization tank equipped with 15ppm of tin octylate to 94kg of Pulac Japan L-lactide (trade name: PURASORB L) and 6kg of the company's DL-lactide (trade name: PURASORB DL), equipped with stirrer and heating device Put in. Nitrogen substitution was performed, and polymerization was performed at 185 ° C. and a stirring speed of 100 rpm for 60 minutes. The obtained melt was subjected to a 40 mmφ co-directional twin-screw extruder manufactured by Mitsubishi Heavy Industries, Ltd. equipped with three stages of vacuum vents, extruded at 200 ° C. into a strand shape while devolatilizing at a vent pressure of 4 torr, and pelletized. .
The obtained polylactic acid polymer had a weight average molecular weight of 200,000 and an L-form content of 97.0%. The melting point by DSC of the pellet after annealing at 120 ° C. for 4 hours was 154 ° C.
In the same manner, the amount of charged L-lactide and DL-lactide was adjusted to prepare a polylactic acid polymer having a weight average molecular weight of 200,000 and an L-form content of 94.8%. The melting point by DSC of the pellet after annealing at 120 ° C. for 4 hours was 145 ° C.

(Production Example 5)
500L batch polymerization tank equipped with 15ppm tin octylate to 85kg of P-luck Japan L-lactide (trade name: PURASORB L) and 15kg of the company's DL-lactide (trade name: PURASORB DL), equipped with stirrer and heating device Put in. Nitrogen substitution was performed, and polymerization was performed at 185 ° C. and a stirring speed of 100 rpm for 60 minutes. The obtained melt was subjected to a 40 mmφ co-directional twin-screw extruder manufactured by Mitsubishi Heavy Industries, Ltd. equipped with three stages of vacuum vents, extruded at 200 ° C. into a strand shape while devolatilizing at a vent pressure of 4 torr, and pelletized. .
The obtained polylactic acid polymer had a weight average molecular weight of 200,000 and an L-form content of 92.6%. The crystal melting point by DSC of the pellet after annealing at 120 ° C. for 4 hours was 131 ° C.

(Production Example 6)
A 500-liter batch polymerization tank equipped with 15 kg of tin octylate added to 80 kg of Pulac Japan L-lactide (trade name: PURASORB L) and 20 kg of DL-lactide (trade name: PURASORB DL) manufactured by the same company, and equipped with a stirrer and a heating device. Put in. Nitrogen substitution was performed, and polymerization was performed at 185 ° C. and a stirring speed of 100 rpm for 60 minutes. The obtained melt was subjected to a 40 mmφ co-directional twin-screw extruder manufactured by Mitsubishi Heavy Industries, Ltd. equipped with three stages of vacuum vents, extruded at 200 ° C. into a strand shape while devolatilizing at a vent pressure of 4 torr, and pelletized. .
The obtained polylactic acid polymer had a weight average molecular weight of 200,000 and an L-form content of 89.7%. There was no crystalline melting point by DSC, and it was confirmed to be amorphous.

  Table 1 summarizes the physical properties of the polylactic acid polymers obtained in Production Examples 1 to 6.

(Examples 1-5 and Comparative Examples 1-3)
The polylactic acid polymer pellets obtained in Production Examples 2 to 6 were dried according to Table 2, and then extruded from the multi-manifold die at 210 ° C. for the other layer (B layer) with a 40 mmφ single-screw extruder. .
In addition, the specific aliphatic polyester used when adding the specific aliphatic polyester to the B layer is Showa High Polymer Co., Ltd .: Bionore # 3003.
Similarly, granular silica having an average particle size of 1.4 μm dried on the polylactic acid polymers obtained in Production Examples 1 to 3 according to Table 2 (trade name: Cicilia 100, manufactured by Fuji Silysia Chemical Co., Ltd.) 1 part by weight was mixed and extruded at 210 ° C. for one layer (A layer) from the above die with a 25 mmΦ same-direction biaxial extruder.

  The extrusion amount was adjusted so that the thickness ratio of the three-layer structure of A layer / B layer / A layer was about 1: 8: 1. This coextruded sheet was quenched with a casting roll at about 43 ° C. to obtain an unstretched sheet. Subsequently, the obtained sheet was heated to 75 ° C. using an infrared heater in contact with a hot water circulating roll using a film tenter manufactured by Mitsubishi Heavy Industries, Ltd. Then, the longitudinally stretched sheet was guided to a tenter while being gripped with a clip, stretched 2.8 times at 75 ° C. in the vertical direction of the sheet flow, and then heat-treated at 135 ° C. for about 30 seconds. A sheet of was created. These sheets were used as laminated sheets of Examples 1 to 5 and Comparative Examples 1 to 5.

The physical properties of the obtained laminated sheet were measured by the above method. The results are shown in Table 2. Examples 1-5 are within the scope of the present invention.
The heating jig was pressed so that the temperature of the A-layer folded portion was 150 ° C., and the above-described thermal bendability and folded portion heat resistance were evaluated. Table 2 shows the transparency of the laminated sheet, the impact resistance, the folding formability, the bending heat resistance, the impact resistance, and the overall evaluation showing the properties of the molded product obtained from the sheet.
It has good transparency and impact resistance, and is suitable for calendar holders and slide blisters that emphasize transparency.

(Example 6)
The polylactic acid polymer obtained in Production Example 6 (L-lactic acid: D-lactic acid = 89.7: 10.3, glass transition temperature 53 ° C., no melting point) 95% by weight and the glass transition point is −45 ° C. Polybutylene succinate / adipate (trade name: Bionore # 3003, manufactured by Showa Kogyo Co., Ltd.), a biodegradable aliphatic polyester having a melting point of 94 ° C., is dried and then mixed and melt extruded. The pellets obtained in the form of pellets were extruded from the multi-manifold die at 210 ° C. with a 40 mmφ single-screw extruder for the other layer (B layer).

  Further, the polylactic acid polymer obtained in Production Example 2 (L-lactic acid: D-lactic acid = 98: 2, glass transition temperature 56 ° C., melting point 162 ° C.) having an average particle size of 1.4 μm dried to 100 parts by weight. Particulate silica (trade name: Cicilia 100, manufactured by Fuji Silysia Chemical Co., Ltd.) 0.1 parts by weight is mixed and 210 ° C. for one layer (A layer) from the above die with a 25 mmφ same-direction biaxial extruder. Extruded with

  The extrusion amount was adjusted so that the thickness ratio of the three-layer structure of A layer / B layer / A layer was about 1: 8: 1. This coextruded sheet was quenched with a casting roll at about 43 ° C. to obtain an unstretched sheet. Subsequently, the obtained sheet was heated to 75 ° C. using an infrared heater in contact with a hot water circulating roll using a film tenter manufactured by Mitsubishi Heavy Industries, Ltd. Then, this longitudinally stretched sheet was guided to a tenter while being gripped with a clip, stretched 2.8 times at 75 ° C. in the vertical direction of the sheet flow, and then heat treated at 135 ° C. for about 30 seconds, A laminated sheet was created. This laminated sheet was used as the laminated sheet of Example 6.

As described above, the melting point of the polylactic acid polymer portion of the front and back layers is 162 ° C., and the melting point of the polylactic acid polymer portion of the intermediate layer does not exist.
The physical properties of the obtained sheet were measured, and the results are shown in Table 2. Further, the heating jig was pressed so that the temperature of the A-layer folded portion was 150 ° C., and the above-described thermal bendability and folded portion heat resistance were evaluated. Table 2 shows the transparency of the laminated sheet, the impact resistance, the folding formability, the bending heat resistance, the impact resistance, and the overall evaluation showing the properties of the molded product obtained from the sheet.
Due to the effect of polybutylene succinate / adipate added to the B layer, the impact resistance is improved as compared with Example 5 where no addition was made. Transparency is also 10% or less, and it is suitable for a relatively light weight packaging slide blister.

(Example 7)
The polylactic acid polymer obtained in Production Example 4 (L-lactic acid: D-lactic acid = 94.8: 5.2, glass transition temperature 56 ° C., melting point 145 ° C.) is 95% by weight and the glass transition point is −45 ° C. Polybutylene succinate / adipate (trade name: Bionore # 3003, manufactured by Showa Polymer Co., Ltd.), which is a biodegradable aliphatic polyester having a melting point of 94 ° C., is dried and mixed to melt. The pellet obtained by extrusion was extruded from the multi-manifold die at 210 ° C. with a 40 mmφ single-screw extruder for the other layer (B layer).

  Further, the polylactic acid polymer obtained in Production Example 2 (L-lactic acid: D-lactic acid = 98: 2, glass transition temperature 56 ° C., melting point 162 ° C.) having an average particle size of 1.4 μm dried to 100 parts by weight. Particulate silica (trade name: Cicilia 100, manufactured by Fuji Silysia Chemical Co., Ltd.) 0.1 parts by weight is mixed and 210 ° C. for one layer (A layer) from the above die with a 25 mmφ same-direction biaxial extruder. Extruded with

  The extrusion amount was adjusted so that the thickness ratio of the three-layer structure of A layer / B layer / A layer was about 1: 8: 1. This coextruded sheet was quenched with a casting roll at about 43 ° C. to obtain an unstretched sheet. Subsequently, the obtained sheet was heated to 75 ° C. using an infrared heater in contact with a hot water circulating roll using a film tenter manufactured by Mitsubishi Heavy Industries, Ltd. Then, this longitudinally stretched sheet was guided to a tenter while being gripped with a clip, stretched 2.8 times at 75 ° C. in the vertical direction of the sheet flow, and then heat treated at 135 ° C. for about 30 seconds, A laminated sheet was created. This laminated sheet was used as the laminated sheet of Example 7.

As described above, the melting point of the polylactic acid polymer portion of the front and back layers is 162 ° C., and the melting point of the polylactic acid polymer portion of the intermediate layer is 145 ° C.
The physical properties of the obtained sheet were measured and the results are shown in Table 2. Further, the heating jig was pressed so that the temperature of the A-layer folded portion was 150 ° C., and the above-described thermal bendability and folded portion heat resistance were evaluated. Table 2 shows the transparency of the laminated sheet, the impact resistance, the folding formability, the bending heat resistance, the impact resistance, and the overall evaluation showing the properties of the molded product obtained from the sheet.
Due to the effect of polybutylene succinate / adipate added to the B layer, the impact resistance is remarkably improved as compared with Example 2 in which it was not added. Transparency is also 10% or less, and it is suitable for slide blisters that require impact resistance.

  Examples 1 to 7 show results above the practical range in the above evaluation measurements, and the overall evaluation is Δ or more. In particular, the overall evaluation of Examples 1, 2, 6, and 7 is “good”. On the other hand, Comparative Examples 1 to 5 which are out of the scope of the present invention are poor in properties of the obtained molded bodies.

(Example 8) [Biodegradability test]
The molded product obtained in Example 2 was put in a household conposter (Ecologo EC-25D, manufactured by Shizuoka Seisakusho Co., Ltd.) together with 20 kg of fully mature humus and 10 kg of dog food (Nippon Pet Food Co., Ltd. Vitawan) While adding 500 ml of water, the sample was allowed to stand for 5 weeks, and the recovery rate after 5 weeks (the rate remaining in the holder) was measured. The recovery was clearly 30% or less, and the decomposition was clearly progressing, indicating good biodegradability.

(A) Plan view showing an example of a sliding blister, (b) Front view of (a) (A) Front view showing an example of a calendar holder, (b) Side view of (a) (A) A plan view showing a state in which a folding line is provided on a polylactic acid laminated sheet for thermal folding molding, (b) a schematic diagram showing a state in which a heating jig is applied to the folding line in (a), and (c) thermal folding. Schematic diagram showing the state of cooling after molding Schematic showing the opening angle in case of calendar holder

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Blister container 2 Product storage part 3 Thermal folding molding part 4 Calendar holder 5 Thermal folding molding part 6 Open end 11 Polylactic acid-type laminated sheet 12 for thermal folding molding Folding line 13 Heating jig 14 Holding plates θ1, θ2 Opening angle

Claims (3)

A layer mainly composed of a polylactic acid polymer, stretched and heat-set, and B layer mainly composed of a polylactic acid polymer having a melting point lower than the melting point of the polylactic acid polymer constituting the A layer In a laminated sheet having
When the melting point of the A layer is Tma (° C.) and the melting point of the B layer is Tmb (° C.), the following formula (1) is satisfied.
180> Tma ≧ 154 and Tma−Tmb> 10 (1)
The heating part ridgeline part of the heating jig is pressed against the laminated sheet, and the temperature of the pressing part of the laminated sheet against which the heating part ridgeline part is pressed is heated to 120 to 150 ° C., The opening angle of the bent portion when the pressing portion is bent and cooled by being sandwiched between holding plates is 1 to 13 °,
And the opening angle of the bending part after leaving said folded laminated sheet for 60 minutes at 60 degreeC in a hot-air oven is 5-19 degrees, The polylactic acid-type laminated sheet for thermal bending shaping | molding characterized by the above-mentioned. In a laminated sheet having a polylactic acid-based polymer as a main component, an A layer stretched and heat-set, and a B layer having a polylactic acid-based polymer having no melting point as a main component,
When the melting point of the A layer is Tma (° C.) and the glass transition point of the B layer is Tgb (° C.), the following formula (2) is satisfied:
180> Tma ≧ 154 and Tma− (Tgb + 70)> 10 (2)
The heating part ridgeline part of the heating jig is pressed against the laminated sheet, and the temperature of the pressing part of the laminated sheet against which the heating part ridgeline part is pressed is heated to 120 to 150 ° C., The opening angle of the bent portion when the pressing portion is bent and cooled by being sandwiched between holding plates is 1 to 13 °,
And the opening angle of the bending part after leaving said folded laminated sheet for 60 minutes at 60 degreeC in a hot-air oven is 5-19 degrees, The polylactic acid-type laminated sheet for thermal bending shaping | molding characterized by the above-mentioned.   Said B layer contains biodegradable aliphatic polyesters other than polylactic acid, The polylactic acid-type laminated sheet for heat bending forming of Claim 1 or 2 characterized by the above-mentioned.

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