JP3193119B2 - Laminated sheet for thermoforming - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated sheet for thermoforming, and more particularly to a laminated sheet suitable as a thermoplastic resin sheet forming a storage chamber of a PTP (press-through pack) package.

[0002]

2. Description of the Related Art A thermoplastic resin sheet for thermoforming, for example, a resin sheet forming a storage chamber in a PTP package for individually storing chemicals such as tablets and capsules has good transparency. That it is moisture-proof, that it can be easily formed by thermoforming such as vacuum forming and compressed air forming, that the formed product has good slippage after forming, that it is easy to accumulate the formed products, and that it has high rigidity. For example, a vinyl chloride resin sheet has been used. However, recently, this resin sheet is problematic in terms of environmental conservation, and alternatives have been sought.

[0003] In response to such a search, unstretched polypropylene resin sheets or unstretched polyester resin sheets have been considered, but these also have problems. That is,
Unstretched polypropylene resin sheets have the following problems. (A) The thermoforming temperature range is narrow. (B) Conventionally used molding machines for vinyl chloride resin sheets cannot be used as they are, requiring modification of the molding machines. (C) There is no seat stiffness.

[0004] The unstretched polyester resin sheet has the following problems. (D) The sheet causes blocking on the heating plate of the molding machine, and the sheet undergoes width shrinkage due to tension for feeding the heated sheet, resulting in insufficient dimensions. (E) The thermoforming temperature range is narrow. (F) Slippage of the molded product is poor, resulting in poor integration. (G) High moisture permeability.

A PTP package comprising a laminated sheet containing a polyethylene terephthalate-based resin layer and a layer of polypropylene or high-density polyethylene has been proposed (Japanese Patent Publication No. 3578/1991). An example is given in which polyethylene terephthalate layers are laminated on both sides. This laminated sheet is intended to be a sheet with high carbon dioxide gas permeability so as to be suitable for special chemical packaging that generates gas when absorbing moisture, but in terms of haze, moldability, slip after molding, etc. Not enough.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems, and the gist of the invention is that the intrinsic viscosity (IV) of a polyester resin is 0.6 or more. on both sides of the layer unstretched polyester resin, MI (melt flow index, the unit g / 10 min) of polypropylene resin unstretched polypropylene a value was measured at 14 JIS K-7210 is a 1 to 4 <br / And the thickness of each of the unstretched polypropylene-based resin layers on both sides is 7 to 14% with respect to the thickness of the unstretched polyester resin layer. In the laminated sheet for thermoforming.

The resin constituting the layer of the unstretched polyester resin in the laminated sheet of the present invention may be one of dicarboxylic acids conventionally known for polyester production, such as terephthalic acid and isophthalic acid as dicarboxylic acid components. A combination of two or more and one or more diols conventionally known for producing polyesters, such as ethylene glycol and diethylene glycol as diol components, is used.

Specifically, polyethylene terephthalate,
Polyethylene composed of polyethylene 2,6-naphthalate, polybutylene terephthalate, and terephthalic acid and 1,4-cyclohexanedimethanol are preferred. Further, terephthalic acid is mainly used as a dicarboxylic acid component, and a small amount of Copolymerized polyesters obtained by copolymerizing those containing ethylene glycol as a diol component and those containing a small amount of diethylene glycol, polyalkylene glycol or 1,4-cyclohexanedimethanol are also used. Such a copolyester is preferable because it can be obtained industrially at low cost.

The intrinsic viscosity of these polyester resins (I
V) is desirably 0.6 or more, and if it is less than 0.6, the strength of the sheet is undesirably reduced. The polyester resin may contain a stabilizer, a lubricant, an ultraviolet absorber and the like as necessary. These polyester resins are formed into a film (or sheet) and laminated, but an unstretched one is used. The stretched material is not formed into a shape faithful to the mold, and is not preferred.

The resin constituting the layer of the unstretched polypropylene resin in the laminated sheet of the present invention includes homopolypropylene, propylene and ethylene, butene-1 and the like.
-Random copolymers with olefins are preferred. Above all, those having an MI (melt flow index, unit g / 10 minutes) of 1 to 4 measured under the condition 14 of JIS K-7210 are preferable in terms of balance between transparency and moldability.
That is, if the MI is less than 1, the transparency deteriorates, and if the MI exceeds 4, stickiness occurs during thermoforming, and the moldability deteriorates.

If necessary, a hydrogenated petroleum resin, an antioxidant, an ultraviolet absorber, other polyethylene, an ethylene-propylene copolymer, or the like may be blended with the polypropylene resin. These polypropylene resins are formed into a film and laminated, but unstretched ones are used. When a stretched film is used, the moldability is adversely affected.

The thickness of the unstretched polyester resin layer in the laminated sheet of the present invention is, for example, 15 for PTP packaging.
Usually, it is in the range of 0 to 240 μm.

In the laminated sheet of the present invention, the thickness (not the total thickness of both sides) of the unstretched polypropylene resin layer laminated on both sides of the unstretched polyester resin layer is determined by the thickness of the unstretched polyester resin layer. 7-14% of the
Within the range. If this value is less than 7%, the width shrinkage after molding is large, the molding temperature range is narrowed, the moldability is poor, and the moisture permeability is increased, which is unsuitable for PTP packaging. On the other hand, if the above value exceeds 14%, the molding temperature range becomes narrow, and the molding machine for vinyl chloride resin sheets conventionally used cannot be used as it is, and the rigidity of the obtained laminated sheet becomes small. , Haze also gets worse.

The production of the laminated sheet of the present invention is carried out by a conventionally known method, for example, a method such as a dry lamination method and a co-extrusion method. In the case of the co-extrusion method, it is preferable to perform adhesion by interposing an adhesive layer between the respective layers.

The laminated sheet of the present invention is useful for producing a PTP package. FIG. 1 is a schematic vertical sectional front view of a PTP package manufactured using the laminated sheet of the present invention.

In the drawing, 1 is a laminated sheet of the present invention, 2 is an unstretched polyester resin layer constituting the laminated sheet 1, 3 and 4 are similarly unstretched polypropylene resin layers, and 5 is a molded sheet of the laminated sheet 1. Storage room for tablets, etc.
Reference numeral 6 denotes a metal foil such as an aluminum foil adhered to close the storage room 5, reference numeral 7 denotes a sewing machine hole provided in the laminated sheet 1 for separating each storage room, and reference numeral 8 denotes a tablet.

[0017]

【Example】

Example 1 A polyethylene terephthalate having an intrinsic viscosity of 0.7 (hereinafter, referred to as a polyethylene terephthalate)
Unstretched polypropylene (hereinafter abbreviated as PP) having the same thickness, that is, 23 μm in thickness, on both sides of a 254 μm-thick unstretched sheet made of PET.
Film (MI = 2 g / 10 min) (PP film / PE
The thickness ratio of the T sheet was 9%) by a dry lamination method to obtain a laminated sheet having a thickness of 300 µm.
For this sheet, the haze, moisture permeability, rigidity, moldability, and slip after molding were measured. The same measurement was performed in Examples and Comparative Examples described later, and the results are shown in Table 1.

Example 2 The thickness of the unstretched PET sheet in Example 1 was 242 μm.
m, the thickness of each of the unstretched PP films to be laminated on both sides of the sheet is 29 μm (the ratio of the thickness of the PP film / PET sheet is 12%), and the total thickness of the sheet is 300 μm. In the same manner as in Example 1, a laminated sheet was obtained.

Comparative Example 1 The thickness of the unstretched PET sheet in Example 1 was 272 μm.
m, except that the unstretched PP films to be laminated on both sides of this sheet each have a thickness of 14 μm (the ratio of the thickness of the PP film / PET sheet is 5.1%) and a total thickness of 300 μm. Was obtained in the same manner as in Example 1.

Comparative Example 2 The thickness of the unstretched PET sheet in Example 1 was 220 μm.
m, except that the thickness of each unstretched PP film to be laminated on both sides of this sheet is 40 μm (the ratio of the thickness of the PP film / PET sheet is 18.2%), and that the total thickness of the sheet is 300 μm. It was the same as in Example 1.

Comparative Example 3 An unstretched PET sheet having a thickness of 300 μm and made of PET having an intrinsic viscosity of 0.7 was used as a comparative product. Comparative Example 4 MI = 2 g / 10 min.
Was used as a comparative product.

Comparative Example 5 A 300 μm thick sheet made of a vinyl chloride resin was used as a comparative product. Comparative Example 6 MI = 2 g / 10 min.
μm unstretched PP sheet, P
ET unstretched PET film (thickness is 5
0 μm) was laminated by a dry lamination method to obtain a laminated sheet having a total thickness of 300 μm, which was used as a comparative product.

The physical properties of the sheets according to the above Examples and Comparative Examples are shown in Table 1. The physical properties are measured by the following methods. Haze: Measured according to JIS K7105 (A).
The unit of the measured value is%. Moisture permeability: According to JIS Z0208. The unit is g / m ² /
It is 24:00.

Rigidity: A sheet formed by forming two rows of five storage chambers each having a length of 20 mm, a width of 7.5 mm, and a depth of 7 mm so as to be used for manufacturing a PTP package body (a total of ten storage chambers). The storage chamber is placed with the opening side facing down, a 2 mm thick vinyl chloride resin plate is placed on top of it, and a load is applied from above, and the molded product has a depth of 60% deformation, that is, the original depth of 7 mm.
On the other hand, a load (unit: g) at which a deformation of 4.2 mm occurs is measured.

Formability: When the sheet is heated to form it into the shape indicated by reference numeral 1 in FIG. 1, the sheet shrinks in the width direction.
If the ratio is equal to or less than the ratio of mm, the molding passes. A pass is obtained if the molded product is finished according to the shape of the mold. If the range of the acceptable temperature is wide, the molding operation is easy and the number of rejected products is small, but if the range of the acceptable temperature is narrow, the molding operation requires careful attention and The number of accepted products also increases. Here, the moldability indicates a temperature range at the time of molding in which good molding can be performed. That is, if this range is wide, it is determined that the moldability is good.

Slip after molding: Two sheets (having a total of 10 accommodation chambers) molded in the same shape as those used in the evaluation of rigidity were overlapped so that the swelled surfaces of the accommodation chambers were in contact with each other. Slide the two sheets in opposite directions. According to such a method, those having the same degree of slippage as when the vinyl chloride resin sheet of Comparative Example 5 was used were evaluated as ○, those with slightly worse slipping as Δ, and those with extremely poor slipping as ×. Shown in

In the measurement of the physical properties described above, when measuring the items of rigidity, moldability, and slip after molding, the sheet was treated with PT.
Molding was carried out for the production of P-package, but this molding
A flat-plate type air vacuum machine was used. The overall evaluation shown in Table 1 is based on the comprehensive evaluation of each characteristic result shown on the left side. The meaning of each mark is based on the vinyl chloride resin sheet of Comparative Example 5 (marked with a circle). ),
A sample having the same degree of quality was evaluated as ○, a sample slightly poorer than this was evaluated as Δ, and a sample judged to be extremely defective was evaluated as ×.

[0028]

[Table 1]

[0029]

The laminated sheet of the present invention has low moisture permeability,
Good transparency, high rigidity, excellent moldability when performing thermoforming, and good slippage after molding. Excellent as a molding sheet, especially as a molding sheet for manufacturing PTP packages. ing.

[Brief description of the drawings]

FIG. 1 is a schematic vertical sectional front view of a PTP package manufactured using a laminated sheet of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Laminated sheet of this invention 2 Unstretched polyester resin layer 3 Unstretched polypropylene resin layer 4 Unstretched polypropylene resin layer 6 Metal foil

Claims (1)

(57) [Claims] 1. The polypropylene resin has an MI (melt flow index, unit: g / 10 min) of JIS K-A on both sides of an unstretched polyester resin layer having an intrinsic viscosity (IV) of 0.6 or more. value measured in the condition 14 of 7210 are stacked layer of an unstretched polypropylene <br/> emissions based resin is 1 to 4, each of the layers of the undrawn poly <br/> propylene resin of the double-sided A laminated sheet for thermoforming, wherein the thickness is in the range of 7 to 14% with respect to the thickness of the unstretched polyester resin layer.