JP2001315207A - Method for producing laminated sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a laminated sheet of olefin resins which is high in rigidity and excellent in thermoforming processability and is used for packaging goods stably without deteriorating its appearance, etc. SOLUTION: An oriented film of an olefin resin is pressed in the shape of an arc at least to one side of an olefin resin sheet extruded in a molten state from a T-die between a metal roll and an endless metal belt to make the laminated sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a laminated sheet which is suitably used in the field of merchandise packaging, in particular, packages obtained by box making and containers obtained by thermoforming.

[0002]

2. Description of the Related Art Conventionally, vinyl chloride resin sheets have been widely used in the field of product packaging, but olefin resin products have been increasingly used due to concerns about environmental pollution. But,
It has been pointed out that packages obtained by box-forming an olefin-based resin sheet have low rigidity and are easily crushed as compared with those of a vinyl chloride resin. Further, in the thermoforming process, drawbacks have been pointed out that a molded product having a uniform thickness cannot be obtained due to dripping of a molten resin at the time of heating, or the appearance of the molded product is impaired.

On the other hand, as a method of laminating a thermoplastic resin, Japanese Unexamined Patent Publication (Kokai) No. 4-31848 discloses a method in which an unmelted thermoplastic resin sheet and a heat-bondable resin film are pressed using a heated metal belt. A method for continuously producing a laminated sheet is described. However, uniform lamination is difficult with the lamination method, and considerable experience and time are required to adjust conditions such as a take-up speed, a draw ratio (a tension control of a feeding tension and a winding tension), and a crimping force. In the case of a sheet having a size of 5 mm or less, incorporation of air bubbles and poor appearance due to poor press bonding often become remarkable.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a laminated sheet having high rigidity and excellent thermoforming workability without any defective press bonding or defective appearance.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems of the present invention, the present inventors have found that an olefin resin sheet extruded in a molten state from the T-die at the time of T-die extrusion molding. The method of manufacturing a laminated sheet in which a stretched film of an olefin-based resin is pressure-bonded in an arc between a metal roll and a metal endless belt to at least one side of a sheet-like material is not suitable for crimping a laminated sheet having high rigidity and excellent thermoforming workability. It has been found that the production method can be stably produced without appearance defects, and the present invention has been completed based on this finding.

The present invention has the following configuration. (1) A laminated sheet characterized in that a stretched film of an olefin resin is pressure-bonded to at least one surface of an olefin resin sheet extruded in a molten state from a T-die in an arc shape between a metal roll and a metal endless belt. Manufacturing method.

(2) The thickness (Ft) of the stretched film and the total thickness (St) of the laminated sheet are 10 μm ≦ Ft ≦ 50 μm
2. The method of manufacturing a laminated sheet according to claim 1, wherein a relationship of 5Ft ≦ St ≦ 200Ft is satisfied.

[0008]

Embodiments of the present invention will be described below. As the olefin resin constituting the olefin resin sheet and the stretched film of the olefin resin used in the present invention, polyethylene, polypropylene, a homopolymer of α-olefin such as polybutene, two or more α-olefins and Random or block copolymers, preferably ethylene, propylene or 1-
Examples thereof include a random or block copolymer containing butene as a main component, and a mixture thereof. As the α-olefin, those having 2 to 12 carbon atoms are preferable. Specifically, ethylene, propylene, 1-butene, 1-pentene,
Examples include 1-hexene, 1-octene, 1-decene, and the like.

The olefin-based resin sheet and the olefin-based resin constituting the stretched film of the olefin-based resin used in the present invention are not particularly limited as long as they are in the above-mentioned ranges. It is particularly preferable from the viewpoint of adhesive strength that the olefin-based resin mainly constituting the stretched film of the above is the same.

If necessary, known antioxidants, neutralizing agents, nucleating agents, antiblocking agents, slip agents, antistatic agents, flame retardants, inorganic fillers and the like are added to the olefin resin described above. May be.

In the present invention, the stretched film of the olefinic resin laminated on at least one side of the olefinic resin sheet has a thickness (Ft) of the stretched film of 10 μm ≦ Ft.
≦ 50 μm and the total thickness of the obtained laminated sheet (S
It is preferable to use one that satisfies 5Ft ≦ St ≦ 200Ft with respect to t). When the thickness of the stretched film and the total thickness of the laminated sheet are in the above ranges, a draw-down suppressing effect at the time of thermoforming can be sufficiently obtained, and shrinkage at the time of heating is reduced, so that the sheet can be suitably used as a thermoforming sheet.

The stretched film of the olefin resin used in the present invention is stretched uniaxially or biaxially, and is preferably a biaxially stretched film, and more preferably a biaxially stretched polypropylene film.

In the method for producing a laminated sheet of the present invention, first, an olefin resin melt-kneaded by an extruder is extruded in a molten state from a T-die 1 shown in FIG. Alternatively, a stretched film 7 of an olefin resin is simultaneously passed through the metal roll 3 and the metal endless belt 6 from the lower portion and pressed. Then, the pressure roll 4
, The metal endless belt 6 is pressed down in an arc shape toward the metal roll 3 and pressed. At this time, the olefin-based resin sheet and the stretched film of the olefin-based resin are face-pressed, and at the same time, the olefin-based resin sheet is cooled and solidified to obtain the laminated sheet 8.

In the above-mentioned manufacturing method, the temperature of the metal roll 3 and the metal endless belt 6 is 30 to 100 ° C., especially 5 to 100 ° C.
The temperature is preferably adjusted to 0 to 70 ° C. in cooling and solidifying the olefin-based resin sheet. Also metal roll 3
The metal endless belt 6 has a surface roughness of JIS B 0
It is preferable to use a flat surface having a maximum height (Ra) of less than 1 μm and a maximum height (Ra) defined in 601 in order to perform uniform pressing.

In the present invention, the clamping force between the metal roll 3 and the metal endless belt 6 is 7 MPa or more, and
It is particularly preferred to be Pa or more. If the clamping pressure is higher than this, the obtained laminated sheet 8 has sufficient adhesion and pressure-bonding properties.

The step of winding the sheet after the completion of the above-mentioned pressure bonding is performed by a known and publicly used method. Specifically, it is commercialized as a roll or cut plate of a predetermined size by using equipment such as a cooling roll, an annealing roll, a trimming cutter, a fixed-size cutting cutter, and a winding machine.

The surface of the laminated sheet of the present invention may be subjected to a surface treatment such as a corona treatment, if necessary, in order to improve the adhesion to printing ink and paint.

The laminated sheet of the present invention is suitably used in the field of merchandise packaging, in particular, packages obtained by box making and containers obtained by thermoforming.

[0019]

EXAMPLES Examples and comparative examples are described below, but the present invention is not limited thereto. In addition, the performance of the obtained sheet was evaluated by the following evaluation.

(1) Young's modulus: Young's modulus was measured according to ASTM D882 as an index indicating the rigidity of the sheet. If the value of the Young's modulus was 1100 MPa or more, it was determined that the sheet could be suitably used as a packaging package.

(2) Evaluation of thermoforming processability: 40 cm × into a thermostat heated to 200 ° C. by an infrared heater.
A sheet sample of 40 cm was attached to the gantry, and the drawdown during melting and the time required for the drawdown amount to be maximum (maximum drawdown required time) were measured. A sheet having a drawdown amount of 30 mm or less and a maximum drawdown time of 30 seconds or less was determined to be a sheet that can be suitably used as a sheet for thermoforming.

(3) Appearance inspection: The appearance of the sheet sample was evaluated by visual observation. A sample without adhesion non-uniformity, gloss non-uniformity, and no air bubbles were mixed. evaluated.

Example 1 Using a single screw extruder having a screw diameter of 65 mm, a polypropylene homopolymer (trade name: Chisso Polypro A5014, manufactured by Chisso Corporation) was used as an olefin resin from a T-die 1 (die temperature 250 ° C.). It is extruded into a sheet in a molten state, and a polypropylene homopolymer (trade name: prepared in advance from above and below as a stretched film 7 of an olefin resin)
A biaxially stretched film of Nisso Polypro A5014 (manufactured by Chisso Corporation) (drawing ratio in the longitudinal direction of the film is 5 times, drawing ratio in the width direction is 8 times, film thickness is 0.03 mm) is fed out, and the olefin resin is fed. The sheet-like material and the stretched film 7 of olefin resin are sandwiched between a belt roll 2 and a metal roll 3 (surface roughness: 0.1 μm) via a metal endless belt 6 (surface roughness: 0.3 μm). Pressed. Thereafter, the pressing roll 4 is lowered from above the metal endless belt 6 and the metal endless belt 6 is pressed against the metal roll 3 in an arc shape.
The laminated sheets 8 were obtained under the condition of a line speed of 4 m / min. At this time, the discharge amount of the molten resin from the extruder was adjusted so that the thickness of the obtained laminated sheet 8 was 0.35 mm. The pressure of the pressure roll 4 was lowered so that the temperature of the metal roll 3 and the metal endless belt 6 was 70 ° C., the clamping pressure was 10 MPa, and the arc length to be clamped was 26 cm. Table 1 shows the evaluation results of the Young's modulus, thermoforming workability, and appearance inspection of the obtained laminated sheet 8. As can be seen from the evaluation results, the laminated sheet was suitable for use as a packaging package and a sheet for thermoforming.

Example 2 A laminated sheet was prepared according to Example 1 except that the line speed was increased to 8 m / min and the discharge rate of the extruder was adjusted so that the thickness of the laminated sheet 8 was the same as that of Example 1. 8 was produced. Table 1 shows the evaluation results of the Young's modulus, thermoforming workability, and appearance inspection of the obtained laminated sheet 8. As can be seen from the evaluation results, the laminated sheet was suitable for use as a packaging package and a sheet for thermoforming.

Example 3 A laminated sheet 8 was manufactured according to Example 1, except that the temperatures of the metal roll 3 and the metal endless belt 6 were changed to 90 ° C. Table 1 shows the evaluation results of the Young's modulus, thermoforming workability, and appearance inspection of the obtained laminated sheet 8. As can be seen from the evaluation results, the laminated sheet was suitable for use as a packaging package and a sheet for thermoforming.

Example 4 A laminated sheet 8 was manufactured in accordance with Example 1, except that the arc length for pressing the sheet was changed to 15 cm. Table 1 shows the evaluation results of the Young's modulus, thermoforming workability, and appearance inspection of the obtained laminated sheet 8. As can be seen from the evaluation results, the laminated sheet was suitable for use as a packaging package and a sheet for thermoforming.

Example 5 A laminated sheet 8 was produced in accordance with Example 1, except that the stretched film 7 was bonded on one side. Table 1 shows the evaluation results of the Young's modulus, thermoforming workability, and appearance inspection of the obtained laminated sheet 8. As can be seen from the evaluation results, the laminated sheet was suitable for use as a packaging package and a sheet for thermoforming.

Comparative Example 1 A laminated sheet 8 was produced in accordance with Example 1 except that the pressure roll 4 was not used (do not descend) and the arc length was set to 0. Table 2 shows the evaluation results of the Young's modulus, thermoforming workability, and appearance inspection of the obtained laminated sheet 8. The laminated sheet had insufficient adhesion of the stretched film 7 and was poor in appearance, and could not be used as a product.

Comparative Example 2 A single-layer sheet 8 was produced in the same manner as in Example 1 except that the feeding of the stretched film 7 was stopped and a single-layer sheet was obtained using only an olefin-based resin sheet from an extruder. Table 2 shows the evaluation results of the obtained single-layer sheet 8 in Young's modulus, thermoforming workability, and appearance inspection. The single-layer sheet had a clean appearance, but had no difference in rigidity from general-purpose olefin-based resins, and had a large drawdown in thermoforming workability evaluation, resulting in poor workability.

Comparative Example 3 An unstretched film 7 laminated on both outer layers of an olefin-based resin sheet was produced from a polypropylene homopolymer (trade name: Chisso Polypro A5014, manufactured by Chisso Corporation). The laminated sheet 8 was manufactured in the same manner as in Example 1 except for changing to (1). The obtained laminated sheet 8
Table 2 shows the evaluation results of Young's modulus, thermoforming workability, and appearance inspection of
Shown in Although the appearance of the laminated sheet was clear, the rigidity was not different from that of a general-purpose olefin resin, and the drawdown was large in the thermoforming workability evaluation, and the workability was poor.

[0031]

According to the method for producing a laminated sheet of the present invention, it is possible to produce a laminated sheet of an olefin resin having good appearance without problems such as poor adhesion. Further, the laminated sheet of the olefin resin obtained by the production method has high rigidity and excellent thermoformability, and thus can be suitably used as a sheet for merchandise packaging.

[0032]

[Table 1]

[0033]

[Table 2]

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a manufacturing method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 T-die 2 Belt roll 3 Metal roll 4 Pressure roll 5 Belt tension roll 6 Metal endless belt 7 Stretched film or unstretched film 8 Laminated sheet or single layer sheet

Continued on the front page F-term (reference) 4F100 AK03A AK03B AK07 BA02 BA16 EC032 EC182 EH112 EH172 EJ192 EJ37B EJ38 EJ882 GB15 GB16 JK01 JL01 JL02 4F211 AA03 AA11 AC03 AD08 AG03 AK07 AM01 AR12 TA01 T05TQT TH13

Claims (2)

[Claims] 1. A stretched film of an olefin resin is pressure-bonded to at least one surface of an olefin resin sheet extruded in a molten state from a T-die in an arc shape between a metal roll and a metal endless belt. A method for manufacturing a laminated sheet. 2. The thickness (Ft) of the stretched film and the total thickness (St) of the laminated sheet are 10 μm ≦ Ft ≦ 50 μm,
2. The method for producing a laminated sheet according to claim 1, wherein a relationship of 5Ft ≦ St ≦ 200Ft is satisfied.