JP3091914B2 - Laminated sheet with thermoformability and barrier properties - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is used for, for example, PTP packaging of pharmaceuticals,
The present invention relates to a laminated sheet having thermoformability and barrier properties.

[Prior art] Conventionally, as a laminated sheet having thermoformability and barrier properties, a vinylidene chloride copolymer having a copolymerization ratio of vinylidene chloride of 80 to 95% by weight is provided on one surface of two thermoformable resin sheets. The coalesced emulsion is applied so as to have a solid content of 3 to 70 g / m ^2, and between each of the applied surfaces, molten polyethylene is extruded so that the thickness becomes 20 to 70 μm, and the total thickness becomes 150 to 200 μm.
A laminated sheet fixed to be 0 μm is known (Japanese Patent Publication No. 49-24587).

The above-mentioned conventional laminated sheet having thermoformability and barrier properties provides the necessary barrier properties with the vinylidene chloride copolymer, and the vinylidene chloride copolymer has a poor thermoformability, so that the heat-forming substrate This is compensated for by supporting the vinylidene chloride-based copolymer in the moldable resin sheet, so that good thermoformability can be obtained as a whole.

In addition, JP-B-49-24587 discloses, as thermoformable resin sheets, vinyl chloride resin sheets, polystyrene sheets, unstretched polypropylene sheets, cellulose acetate sheets, polycarbonate sheets, and unstretched high-density polyethylene sheets. However, among these, since a vinyl chloride resin sheet is rich in economy and thermoformability, in the actual market, a sheet using a hard vinyl chloride resin sheet is mainly used.

[Problems to be Solved by the Invention] However, the thermoformable resin sheet is a base material of the laminated sheet, and constitutes most of the laminated sheet, and uses a rigid vinyl chloride resin sheet for this. Has a problem in waste disposal because it contains a large amount of chlorine.

That is, if buried in the soil, it may be decomposed in a long period of time to produce chlorine-based harmful substances (for example, dichloroethylene suspected of carcinogenicity), and when incinerated, chlorine gas is generated. In addition to damaging the living environment, it also causes depletion of the ozone layer surrounding the earth.

Therefore, it is desired to form a laminated sheet without using a hard vinyl chloride resin sheet which causes such a problem.

However, the other thermoformable resin sheets described in the above-mentioned JP-B-49-24587 have a problem that it is more difficult to obtain better thermoformability as a hard vinyl chloride resin sheet. It is also conceivable to select and use a resin which is not described in JP-B-49-24587 and has good thermoformability, but it impairs the laminated vinylidene chloride copolymer layer having poor moldability. There is a possibility that problems such as the above may occur.

On the other hand, a laminated sheet using a vinyl chloride resin sheet as a base material is rich in moldability, but if a laminated sheet having more excellent moldability is obtained, there is no doubt that it is extremely useful in industry.

That is, when the laminated sheet is thermoformed and provided for PTP packaging or the like, if the thermoforming can be performed at a lower temperature, the molding cycle can be shortened and the production efficiency can be increased. Therefore, good thermoformability at a lower temperature is desired.

It is considered that the above-mentioned demand can be solved by using a resin sheet that can obtain good moldability at a lower temperature than a vinyl chloride resin sheet as a base material. However, even if the base material is rich in low-temperature thermoformability, the laminated vinylidene chloride-based copolymer does not necessarily come to be formed in the same manner, and may adversely affect the vinylidene chloride-based copolymer layer. is there.

The present invention has been made in view of the problems of a vinyl chloride resin, and is intended to provide a resin that does not cause a problem at the time of waste disposal, and to obtain thermoformability equal to or higher than that obtained when a vinyl chloride resin is used. Is a problem to be solved.

[Means and Actions for Solving the Problems] Means taken in the present invention to solve the above-mentioned problems will be described. In the present invention, the copolymerization ratio of vinylidene chloride on one surface of the amorphous polyester sheet 2 is reduced. A means is employed in which a laminated sheet is formed by laminating 80 to 95% by weight of vinylidene chloride-based copolymer 1 at a rate of 3 to 120 g / m ² (solid content) (see FIG. 1).

The laminated sheet according to the present invention has a thickness of 15 by facing two laminated sheets of the vinylidene chloride-based copolymer 1 together.
When used as a laminated sheet (see FIG. 2) fixed through polyethylene having a thickness of up to 70 μm, it is preferable because the barrier property is improved and the bending strength is also improved.

 Further, the present invention will be described.

First, the amorphous polyester used as the base sheet in the present invention provides good moldability to the laminated sheet, and is obtained, for example, by controlling the crystallinity of the polyester (hereinafter referred to as “PET”) by polymer modification. be able to. Currently, some of the glycol components are 1,
It is obtained by controlling the crystallization rate of PET by substituting 4-cyclohexanedimethanol.

Amorphous PET has good thermoformability because it is amorphous,
Further, since the glass transition point is as low as about 81 ° C., thermoforming at a relatively low temperature is possible. In the present invention, the amorphous PE
The reason why the T-sheet 2 is used as the base material is not merely that the thermoformability is good, but that the excellent moldability is exhibited without damaging the layer of the vinylidene chloride copolymer 1 laminated thereon. That's why.

In the present invention, the above-mentioned amorphous PET sheet 2 is used as a base material, and its thickness is preferably 150 to 350 μm. If the thickness of the amorphous PET sheet 2 is too small, it is difficult to obtain the necessary formability. Conversely, if the thickness is excessively large, the formability is not further improved, and waste increases. When the laminated sheet of the present invention is in the laminated state shown in FIG. 2, the thickness of the amorphous PET sheet 2 is preferably 100 to 250 μm for the same reason as described above.

The vinylidene chloride-based copolymer 1 provided on one side of the amorphous PET sheet 2 provides a barrier property to the laminated sheet. The vinylidene chloride-based copolymer emulsion is applied to the amorphous PET sheet 2 and dried. Are laminated.

The vinylidene chloride copolymer 1 has a copolymerization ratio of vinylidene chloride of 80 to 95% by weight. If the monomer ratio of vinylidene chloride is less than 80% by weight, good barrier properties cannot be obtained. If the monomer ratio of vinylidene chloride exceeds 95% by weight, polymerization becomes difficult and the stability of the emulsion becomes poor. And it becomes difficult to laminate the vinylidene chloride-based copolymer 1 by coating and drying the emulsion.

Monomers suitable for composing vinylidene chloride-based copolymer 1 by copolymerizing with vinylidene chloride include, for example, vinyl chloride, acrylonitrile, methyl methacrylate,
Examples thereof include methyl acrylate, ethyl acrylate, and vinyl acetate, and one or more of these can be used.

The lamination amount of the vinylidene chloride copolymer 1 is 3 to 120 g / m.
² (solid content), and preferably 5 to 70 g / m ² (solid content). If the amount of the vinylidene chloride-based copolymer 1 is too small, the necessary barrier properties cannot be obtained. On the other hand, if the amount is too large, the number of times of coating and drying for lamination increases and the production efficiency deteriorates. Is more likely to occur. The amount of the vinylidene chloride-based copolymer 1 to be laminated is the same when the laminated sheet of the present invention is used in the laminated state shown in FIG.

The vinylidene chloride-based copolymer 1 is, as described above,
Intended to be stacked by coating and drying a vinylidene copolymer emulsion chloride, during the coating, 3~120g / m ² coating amount is in terms of solid content, and preferably no greater 5 to 100 g / m ^2,
What is necessary is just to apply.

When laminating the vinylidene chloride copolymer 1 by the above-mentioned coating, the coating surface may be subjected to an anchor coat treatment in advance.

As a coating method of the vinylidene chloride copolymer emulsion, for example, an air knife coat, a gravure coat, a smoothing coat, a roll coat, or the like can be used.

After the coating of the vinylidene chloride copolymer emulsion, the water is dried to promote crystallization of the vinylidene chloride copolymer, and the amorphous PET sheet 2 is heated by a heat as a drying temperature of a coater for providing a barrier property. The temperature must not cause deformation. On the other hand, if the temperature is too low,
The vinylidene chloride-based copolymer emulsion is not sufficiently dried, the crystallization of the vinylidene chloride-based copolymer 1 does not proceed, barrier properties are not obtained, and blocking tends to occur. Therefore, it is preferable to perform drying at a temperature of 70 to 150 ° C.

When the laminated sheet of the present invention is in the laminated state shown in FIG. 2, one side of each of the two amorphous PET sheets 2
After the anchor coat is applied as necessary, the vinylidene chloride-based copolymer 1 may be laminated, and the surfaces of the vinylidene chloride-based copolymer 1 may be fixed with polyethylene 3.

The fixation by the polyethylene 3 can be easily performed by a polyethylene extrusion lamination method. That is, two amorphous PET sheets 2 each having the vinylidene chloride-based copolymer 1 laminated on one surface are drawn with the vinylidene chloride copolymer 1 facing each other, and the molten polyethylene is extruded from a T-die between the two. Can be laminated.

The thickness of the polyethylene 3 needs to be 15 to 70 μm, and preferably 30 to 50 μm. If the thickness of the polyethylene 3 is too small, it is difficult to obtain a sufficient adhesive strength. On the other hand, if the thickness is too large, the amorphous PET sheet 2 tends to be thermally deformed during lamination.

At the time of this lamination, the surface of the vinylidene chloride copolymer 1 serving as an adhesive surface may be subjected to an anchor coat treatment, if necessary. As the anchor coating agent, for example, an alkyl coating agent such as an alkyl titanate type, a polyisocyanate type, or a polyalkyleneimine type such as polyethyleneimine can be used.

In particular, the laminated sheet shown in FIG. 2 laminated by using the polyethylene 3 has substantially the same thickness as the layer of the vinylidene chloride copolymer 1 and has improved barrier properties and a buffer made of the polyethylene 3. By the action, a laminated sheet having excellent bending strength is obtained.

In the laminated film of the present invention, the total thickness is 150 to 1
000 μm, particularly preferably 170 to 400 μm. 150
If it is less than μm, it will not be suitable for applications such as PTP
If it exceeds μm, amorphous PE is considered from the viewpoint of maintenance of moldability.
The thickness of the T sheet 2 becomes unnecessarily large, causing waste. When the laminated sheet of the present invention is used in the laminated state shown in FIG. 2, the total thickness of the laminated sheet shown in FIG.
It is preferably from 0 to 2000 μm, particularly preferably from 230 to 600 μm. If the thickness is less than 200 μm, it is difficult to obtain the thickness of the amorphous PET sheet 2 and the thickness of the polyethylene 3 necessary for maintaining the moldability and the adhesive strength. It becomes unnecessarily large and waste increases.

[Example] Example 1 "PETG sheet" (250 µm thickness) manufactured by Eastman Kodak Co., Ltd. was used as an amorphous PET sheet, and an isocyanate-based anchor coating agent ("Coronate L" manufactured by Nippon Polyurethane Industry Co., Ltd.) was used on one surface. "Hylon 30S" manufactured by Toyobo
S "and a 5% solids solution of ethyl acetate) were applied and dried. Thereafter, a vinylidene chloride copolymer emulsion ("Saran Latex L-509" manufactured by Asahi Kasei Kogyo Co., Ltd.) was applied and dried on the anchor coat surface.

The above-mentioned vinylidene chloride copolymer emulsion is applied and dried by air knife coating, and the total thickness is 27
A 5 μm main laminate sheet was produced.

About this laminated sheet, the formability evaluation by hot plate heating pressurized air and vacuum forming was performed as follows.

It has a circular shape with a diameter of 92 mm and a depth of 23 mm (forming draw ratio 0.25).
Molding was performed to form a rounded container having a radius of about 2 mm around the bottom. The molding was performed while increasing the temperature of the hot plate at intervals of 10 ° C., and the radius of the roundness formed around the bottom of the obtained molded product was measured.

FIG. 3 shows the results. The mold reproducibility was determined to be good when the measured radius of the roundness around the bottom of the molded product was in the range of 1.5 to 3 mm.

Further, among the obtained molded products, those having a roundness of a radius of 2 mm were measured for the thickness of each part of the molded product, and the change of the thickness was examined.

 The result is shown in FIG.

Comparative Example 1 Measurement of the radius of roundness was performed in the same manner as in Example 1 except that the amorphous PET sheet was changed to a vinyl chloride resin sheet having a thickness of 230 μm, and a vinylidene chloride copolymer was laminated thereon to a thickness of 25 μm. The thickness was measured.

 The results are shown in FIGS. 3 and 4.

Example 2 The roundness was measured in the same manner as in Example 1 except that a container having a circular shape with a diameter of 37 mm and a depth of 18.5 (molding draw ratio: 0.5) was molded.

 The results are shown in FIG.

In addition, among the obtained molded products, the thickness of each part of the molded product having a roundness radius of 1.5 mm was measured, and the state of change in the thickness was examined.

 The results are shown in FIG.

Comparative Example 2 Measurement of the radius of roundness was performed in the same manner as in Example 2 except that the amorphous PET sheet was changed to a vinyl chloride resin sheet having a thickness of 230 μm, and a vinylidene chloride copolymer was laminated thereon to a thickness of 25 μm. The thickness was measured.

 The results are shown in FIGS. 5 and 6.

Example 3 A vinylidene chloride-based copolymer layer was laminated on a 250-μm sheet of the same amorphous PET as in Example 1 so as to have a thickness of 50 μm, and a polyethyleneimine-based anchor coat agent (BASF) was formed on the surface thereof. Co., Ltd.) is coated by gravure coating method, two of them are faced to each other with an anchor coating surface, and molten polyethylene (thickness: 35 μm) is extruded from a T-die in between and laminated, and a laminated sheet having a total thickness of 635 μm is formed. Produced.

The water vapor transmission rate of the laminated sheet was measured to be about 0.27 g / m ² · 24 h. In addition, the measurement of the water vapor transmission rate was performed based on JIS.

[Effects of the Invention] The present invention is as described above, and has the following effects.

(1) Since an amorphous PET sheet is used as a base material and does not contain chlorine as in the case of a vinyl chloride resin sheet, there is no harm caused by the chlorine content in its disposal, thereby preventing waste pollution. be able to.

(2) It is possible to obtain thermoformability and barrier properties equal to or higher than the case where a vinyl chloride resin sheet is used as a substrate.

(3) Since the molding temperature is low, the molding cycle can be increased to improve the productivity of the molded article.

[Brief description of the drawings]

FIG. 1 is a sectional view of a laminated sheet according to the present invention, FIG. 2 is a sectional view of a laminated sheet obtained by further laminating the laminated sheet of the present invention,
3 and 4 are graphs showing the results of Example 1 and Comparative Example 1, and FIGS. 5 and 6 are graphs showing the results of Example 2 and Comparative Example 2. 1: Vinylidene chloride copolymer 2: Amorphous polyester sheet 3: Polyethylene

Continuation of front page (56) References JP-A-63-197642 (JP, A) JP-A-51-88581 (JP, A) JP-A-1-121334 (JP, A) JP-A-49-24587 (JP) , B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) B32B 1/00-35/00 B29C 51/00-51/46

Claims (1)

(57) [Claims] (1) A vinylidene chloride copolymer having a copolymerization ratio of vinylidene chloride of 80 to 95% by weight is laminated on one surface of an amorphous polyester sheet at a rate of 3 to 120 g / m ² (solid content). A laminated sheet having thermoformability and barrier properties.