JPH0725119B2 - Method for producing composite plastic sheet - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention can further improve transparency and moisture resistance by proper stretching, and hardly cause delamination or layer cutting even by vacuum forming and / or pressure forming. The present invention relates to a method for manufacturing a composite polyolefin sheet.

2. Description of the Related Art Since a polyolefin (PO) thin layer body does not necessarily have the properties according to a wide variety of practical purposes, it can be improved by lamination (composite) to give the properties required for those applications. There are many.

However, despite the fact that polyethylene (PE) and polypropylene (PP) are closely related compounds, as a result of lack of compatibility,
It was impossible to produce the laminate of both by fusion, and it could not be put to practical use.

The following is a conventional stacking technique that causes such a defect.

(1) A solid outer layer film is laminated from both sides of a solid core layer with an adhesive interposed (dry lamination) (2) Three dies are provided at positions where both sides of the core layer are sandwiched by outer layers , Each layer is laminated simultaneously with extrusion (coextrusion).

The composite sheet obtained by these existing lamination methods cannot satisfy the requirements of the present invention in terms of productivity, transparency, moldability, moisture resistance and the like.

Further, as a lamination method which is likely to be misunderstood because it seems to be close to the method of the present invention, there is a sandwich lamination method shown below.

(3) A thin core layer is sandwiched between the outer layers having a thickness sufficient to form a base layer.

However, according to these above-mentioned lamination methods, the performance aimed at by the present invention-delamination or layer cutting is unlikely to occur even when forming a recess, and the transparency and moisture resistance of the recess are improved-
Almost no composite sheet with is obtained.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the present invention, the stretch orientation further improves the moisture-proof property and also improves the transparency.

The main purpose is to prevent a large drawdown at the molding temperature, which is a drawback of the PP layer or PE layer single layer.Furthermore, due to the specific laminated structure, the core layer also has the air pressure moldability, vacuum moldability and stretch orientation property. The purpose is to improve dramatically.

Due to this improvement, neither delamination nor layer cutting occurs when forming a recess in the composite sheet, and conversely, the recess having improved transparency and moisture proof by the appropriate stretch orientation generated when forming the recess. A polyolefin sheet having is obtained. This sheet can be fully used for packaging medicines, foods, cosmetics and the like.

Means for Solving the Problems According to the present invention, a polypropylene-based polymer as an outer layer having a thickness of 120 to 800 μm on both sides of a core layer made of high-density polyethylene in a fusible state is used. 15 to each
A composite plastic sheet characterized in that a film in a solidified state having a thickness of 80 μm and a core layer thickness of 2.5 times or more of the total thickness of outer layers on both sides is fused at the same time. A manufacturing method is provided.

The present invention comprises a crystalline ethylene polymer having a thickness of 120 to 800 μm, which is in a fusible state, from both sides of a core layer, and an outer layer made of a crystalline propylene polymer.
The present invention relates to a method for obtaining a composite sheet having a total thickness of 150 to 960 μm by fusing a solidified film having a thickness of 15 to 80 μm and a core layer thickness / outer layer thickness ≧ 2.5.

Action The method for producing the composite sheet of the present invention is characterized by the lamination method and the bonding with the material resin.

The extrusion double-sided simultaneous laminating (laminating) method, which is one of the features of the method of the present invention, is based on an idea completely different from the ordinary laminating method, and is a completely different idea even from the existing sandwich lamination method. .

That is, in the method of the present invention, since the core layer is the base layer of the composite sheet, it needs to be sufficiently thick, and even if it is thin, it has a completely different mission from that of a normal sandwich laminate core layer that can sufficiently function. Not only is
Since the outer layer of the composite sheet of the present invention is provided as a reinforcing layer, it is sufficient if it has the minimum thickness necessary for its function, whereas the outer layer of a normal laminate is sufficiently thick as a base layer. It is clear that one should expect a completely different kind of effect from what should be done.

An example of the extrusion double-sided simultaneous laminating method of the present invention is shown in FIG. 1. The core layer 1 includes a die 2 to a first roll 5 and a pressing roll 4.
In the molten state in the vicinity of the pressure contact, preferably on the pressure contact, and the outer layer films 3 and 3'are adhered to both surfaces of this core layer by the pressure contact of the first roll 5 and the pressing roll 4. The composite sheet 8 is formed through the second roll 6 and the third roll 7.

The sensible heat (about 170 ° C.) of the resin of the core layer is used for welding the outer layer film and the core layer in the composite sheet. P
Although it is difficult for P and PE to be welded by nature, a good composite sheet that can maintain appropriate adhesion by interposing an adhesive on the interposing surface or by using a specific propylene-based polymer as the outer layer, as described below. Is obtained.

The high-density polyethylene is preferably in the above range in order to improve the strength, transparency and moisture resistance of the composite sheet, and further to obtain rigidity suitable for the ease of taking out the content (article).
Among them, the ratio of melt flow rate, that is, MFR ₁₀ (190
C.) / MFR ₂ of 1 to 10 is preferred.

The propylene-based polymer that constitutes both layers is composed of polypropylene 60 to 97% by weight and ethylene polymer 40 to 3% by weight (total 100% by weight). From the viewpoints of transparency and strength, it is preferably used. This polypropylene is a polymer having propylene units of at least 90 mol% or more, and its melt flow rate is preferably 0.5 to 20.

The ethylene polymer also has the effect of improving the adhesion to the outer core layer. This ethylene-based polymer is a homopolymer of ethylene containing 50 to 100 mol% of ethylene, or a copolymerizable monomer other than ethylene, particularly a copolymer of at least one type of α-olefin with ethylene.

Such ethyne-based polymers include low crystalline or amorphous (that is, rubber) such as ethylene-propylene copolymer and ethylene-butene copolymer, high density polyethylene, medium density polyethylene, low density polyethylene. , And a crystalline copolymerizability of ethylene and other α-olefins, among which the following polymers can be shown as suitable examples.

(I) Low crystalline or amorphous copolymer of ethylene-propylene (rubber) Ethylene unit content 50 to 90 mol%, MFR ₂ (230 ° C) 0.1 to
20g / 10min, (ii) ethylene-1-butene low crystalline or amorphous copolymer (rubber) ethylene unit content 50-90 mol%, MFR ₂ (230 ° C) 0.1-
20g / 10min, (iii) crystalline polymer of ethylene MFR ₂ (190 ° C) 2-20g / 10min, density 0.900-0.975g / c
m ³ , (iv) High-density, medium- or low-density crystalline copolymer MFR ₂ (190 ° C) _{2 to} 20g / 10min, density 0.900 to 0.975g / c consisting of ethylene and another 1-olefin
m ³ , comonomer: 1-olefin containing 3 to 20 carbon atoms, for example propylene, 1-butene, 1-pentene,
1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, comonomer content: 0 to 20 mol%.

Part or all of the various olefin-based polymerizations or copolymers described in (i) to (iv) above may be modified products with unsaturated carboxylic acids or acid anhydrides thereof.

Preferred unsaturated carboxylic acids and acid anhydrides thereof are maleic acid, norbornene dicarboxylic acid, (meth) acrylic acid, maleic anhydride and norbornene dicarboxylic acid anhydride.

The composition ratio of the polypropylene and the ethylene-based polymer forming the outer layer is preferably within the above range in order to ensure suitable adhesiveness between the core layer and the outer layer.

Since the outer layer has the above composition ratio, the composite sheet used in the present invention has an adhesive force of 300 g / cm between the core layer and the outer layer.
Above, especially 500 g / cm 2 or more is preferable.

The composite sheet usually has a thickness of 150 to 960 μm, the core layer has a thickness of 120 to 800 μm, the outer layers on both sides are in the range of 15 to 80 μm, and the thickness of the core layer is on both sides. Is more than 2.5 times the total thickness of the outer layers.

The core layer needs to be thick enough as the base layer of the composite sheet,
Further, both outer layers are provided in order to compensate for the fact that the high-density polyethylene constituting the core layer is inferior in vacuum and / or pressure air moldability and stretch orientation, and the thickness range and ratio deviate from this range. .

The composite sheet provided by the method of the present invention is used for various packages by pressure forming and / or vacuum forming the composite sheet to form a recessed portion, which is pressed and integrated with a metal foil to seal the recessed portion. It is preferably used for.

In this case, the metal foil used is a foil of various metals such as aluminum, and its thickness is usually 10 to 10
It is in the range of 0μ, especially 15 to 60μ.

Above all, when the package of the present invention is used for press-through packaging, an aluminum foil that can be pressed and broken with an appropriate force is suitable as the metal foil.

At least the side of the metal foil that is pressed and integrated with the composite sheet is preferably an adhesiveness improving substance, for example, one coated with an adhesive polyolefin, and as the adhesive polyelefin, a polyolefin such as polypropylene is used as a halogen such as chlorine. An example is a halogenated polyolefin modified by.

That is, the nominal size composite sheet is continuously heated to be in a moldable state, and the composite sheet is suctioned with air pressure and / or vacuum in the mold to form the recessed portion. After filling the contents into the formed recess, Al foil is attached, and then the process such as punching, perforation and printing is performed. Depending on the orientation of the film for the outer layer and the orientation at the time of forming the composite sheet, vacuum formability or /
In addition to improving the air pressure moldability, the moisture resistance and transparency are also improved.

The main molding is performed at 120 to 140 ° C, preferably 125 ° C or higher and 135 ° C or lower.

The degree of orientation can be changed by the heating temperature at the time of pressure forming or / and vacuum forming, and the moisture resistance and the transparency of the package obtained by the fact that pressure forming or / and vacuum forming at low temperature becomes possible are further improved. .

Examples 1 to 8 First by the extrusion double-sided simultaneous laminating method shown in FIG.
The three-layer composite sheet shown in the table was molded. However, the high density polyethylene (HDPE) of the core layer had the following physical properties in all cases.

HDPE: MFR ₂ (190 ° C) = 5.5g / 10min Density 0.968g / cc Weight average molecular weight 67,000 MFR ₁₀ / MFR ₂ = 9.0 The propylene-based polymer used in the outer layer is one of the polymers shown in Table 1. It consists of composition ratios, and the physical properties of each component are as follows.

PP: MFR ₂ (230 ° C) = 6.0g / 10cc Ethylene content 4 mol% EPR: Ethylene-propylene copolymer rubber Ethylene unit content 80mol% MFR ₂ (230 ° C) = 2g / 10min LLDPE (1) : Ethylene-4-methyl-1-pentene copolymer ethylene unit content 97 mol% MFR ₂ (190 ° C.) = 2.0 g / 10 minutes LLDPE (2): ethylene-1-butene copolymer ethylene unit content 97.5 Mol% MFR ₂ (190 ° C) = 2.0g / 10min LDPE: Low density polyethylene Density 0.921g / cc Weight average molecular weight = 112,000 Next, from each composite sheet in Table 1, low temperature conditions (125 Vacuum / pneumatic molding under ~ 128 ° C) and vacuum / pneumatic molding under high temperature conditions (130-135 ° C)
Recess for No. capsule (dimensions: length 20.6 mm, width 8.8 mm,
(Depth of 7.4 mm) was molded, and was pressed and integrated with an aluminum foil to manufacture the package of the present invention.

The aluminum foil used here was coated with chlorinated polypropylene to a thickness of 6 μm on the surface of the aluminum foil having a thickness of 20 μm and pressed against the composite sheet.

The performance of the obtained package was measured and evaluated as shown in Table 2.

However, each performance was evaluated by the following methods.

○ …… Good, △ …… Slightly good, × …… Poor The measurement conditions are shown below.

DD: Drawdown property (unit: mm) The composite sheet was horizontally sandwiched between clamps with a span of 500 mm, and the amount of reduction (mm) in the central part after 55 seconds was measured.

Water vapor transmission rate: Unit (× 10 ^-6 g / 24 hr / mmHg / 1 pocket) JIS Z-
Condition B based on 0208: temperature 40 ° C, relative humidity 90
It is the measured value under the condition of%.

However, the size of one pocket is the size of the recess for the No. 2 capsule.

Transparency: Shown in transmittance unit (%).

Permeability (%) at the bottom of the package pocket (concave)
Was measured using light having a wavelength of 555 mμ. Measurement is AS
Based on TMD1003.

Ease of taking out the contents: By pressing the bottom of the pocket part of the package containing the pharmaceutical capsule from the composite sheet side with a finger and crushing the pocket part, the aluminum foil can be pressed and broken by the pharmaceutical capsule. Then, the operation of taking out the medicinal capsule was carried out, and it was evaluated whether or not the rigidity and the flexibility when the pocket portion was crushed by the finger were appropriate.

Example 9 A composite sheet was produced by the dry lamination method to obtain the composite sheet shown in Table 1.

That is, the same 30 μm-thick film made of PP as in Example 1 was laminated on both sides of a preformed 450 μm-thick sheet of HDPE similar to that of Example 1 via polyurethane adhesives. Made into a composite sheet.

This composite sheet was subjected to the same pneumatic / vacuum forming as in Example 1 to produce the same packaging material.

The evaluation results of this packaging material are shown in Table 2.

Comparative Example Example 9 was repeated except that both outer layers were made of polyvinyl chloride film. The results are shown in Table 2.

Examples 10 to 14 Composite sheets were formed under the same conditions as in Example 1 except that the thicknesses of the core layer and the outer layer were set to the values shown in Table 3, and the same was used as a package.

The performance of each package was evaluated in the same manner as in Example 1. The results are shown in Table 4.

EFFECTS OF THE INVENTION As can be seen from Tables 1 to 4, the composite sheet of the present invention is superior to conventional products in terms of pressure forming property and / or vacuum forming property, moisture resistance, transparency and easiness of taking out contents. Excellent process, especially the adoption of the extrusion double-sided simultaneous laminating method makes the process simpler than the dry laminating method.

[Brief description of drawings]

FIG. 1 (1) is an elevation view of an example of a composite sheet manufacturing apparatus, and FIG. 1 (2) is a laterally enlarged sectional view of the sheet. 1 ... Intermediate layer, 2 ... Die, 3, 3 '... Surface layer, 4 ...
… Presser roll, 5 …… first roll, 6 …… second roll,
7 ... Third roll, 8 ... Composite sheet, 8 (1), 8
(1 ') ... outer layer, 8 (2) ... core layer.

Claims (5)

[Claims] 1. A propylene-based polymer as an outer layer having a thickness of 15 to 80 μm on both sides of a core layer having a thickness of 120 to 800 μm, which is made of high-density polyethylene in a meltable state, and has a thickness of 15 to 80 μm. A method for producing a composite plastic sheet, characterized in that a film in a solidified state in which the thickness of the core layer is 2.5 times or more the total thickness of the outer layers on both sides is fused at the same time on both sides. 2. The propylene-based polymer of both outer layers constituting the composite sheet is composed of polypropylene 60 to 97% by weight and ethylene polymer 40 to 3% by weight (total 100% by weight). A method for producing a composite sheet according to claim (1). 3. Polypropylene is a polymer containing 90 mol% or more of propylene units and has MFR ₂ (230 ° C.) of 0.5 to 20.
And the ethylene polymer contains 50 to 100 mol% of ethylene.
The method for producing a composite sheet according to claim (2), characterized in that it is a homopolymer of ethylene or a copolymer of ethylene with at least one kind of other α-olefins other than ethylene. . 4. The MFR ₂ (190 ° C.) of the high-density polyethylene of the core layer constituting the composite sheet is 2 to 20, and the density is 0.94.
The method for producing a composite sheet according to claim (2), characterized in that the amount is 0.98 g / cc. 5. High density polyethylene MFR ₁₀ (190 ° C.) / MF
The method for producing a composite sheet according to claim (4), wherein R ₂ (190 ° C.) is 1 to 10.