METHOD FOR MANUFACTURING LAMINATE AND CO-EXTRUDED SHEET

Abstract

The present invention provides a method for manufacturing a laminate, comprising the step of co-extruding a polycarbonate and an adhesive composition to thereby form a polycarbonate layer (A) and an adhesive layer (B) at least a part of which is laminated to the layer (A); and the step of heat-treating the polycarbonate layer (A) and the adhesive layer (B), wherein the adhesive composition satisfies the following requirements (i) to (iii): (i) comprising a polyolefin formed through a reaction between a polyolefin (a) having a group reactive with a carbodiimide group and a carbodiimide group-containing compound (b); (ii) comprising carbodiimide groups in an amount of 0.1 to 50 mmol per 100 g of adhesive composition; and (iii) having a density of 0.870 g/cm.sup.3 to 0.940 g/cm.sup.3.

Claims

1. A method for manufacturing a laminate, comprising the step of co-extruding a polycarbonate and an adhesive composition to thereby form a polycarbonate layer (A) and an adhesive layer (B) at least a part of which is laminated to the layer (A); and the step of heat-treating the polycarbonate layer (A) and the adhesive layer (B), wherein the adhesive composition satisfies the following requirements (i) to (iii): (i) comprising a polyolefin formed through a reaction between a polyolefin (a) having a group reactive with a carbodiimide group and a carbodiimide group-containing compound (b); (ii) comprising carbodiimide groups in an amount of 0.1 to 50 mmol per 100 g of adhesive composition; and (iii) having a density of 0.870 g/cm.sup.3 to 0.940 g/cm.sup.3.

2. The method for manufacturing a laminate according to claim 1, wherein the co-extruding step is a step of co-extruding the polycarbonate and the adhesive composition with a resin other than the polycarbonate or a resin contained in the adhesive composition to thereby form the polycarbonate layer (A), the adhesive layer (B), and a layer (C) formed of the resin other than the polycarbonate or the resin contained in the adhesive composition, wherein the layer (C) is laminated to the adhesive layer (B); and the heat-treating step is a step of heat-treating the polycarbonate layer (A), the adhesive layer (B), and the layer (C).

3. The method for manufacturing a laminate according to claim 2, wherein the resin other than the polycarbonate or the resin contained in the adhesive composition comprises a polyolefin.

4. The method for manufacturing a laminate according to claim 1, wherein the polycarbonate is a polycarbonate or a copolycarbonate obtained by reacting a dihydroxy compound and phosgene or diphenyl carbonate.

5. The method for manufacturing a laminate according to claim 4, wherein the dihydroxy compound is 4,4-dihydroxy-diphenyl-2,2-propane (bisphenol A).

6. The method for manufacturing a laminate according to claim 1, wherein the laminate is for use in a packaging container for foods.

7. The method for manufacturing a laminate according to claim 1, wherein at least one of the co-extruding step and the heat-treating step is performed at 260 C. or more.

8. The method for manufacturing a laminate according to claim 1, wherein the co-extruding step is performed at 260 C. or more, and the heat-treating step is performed at 60 C. or more.

9. The method for manufacturing a laminate according to claim 8, wherein the heat-treating step is performed by heating for 4 minutes or more in water at 60 C. or more.

10. A co-extruded sheet comprising a laminate as a part thereof, the laminate comprising a polycarbonate layer (A) formed of a polycarbonate and an adhesive layer (B) at least a part of which is laminated to the layer (A), wherein the adhesive layer (B) is formed of an adhesive composition satisfying the following requirements (i) to (iii): (i) comprising a polyolefin formed through a reaction between a polyolefin (a) having a group reactive with a carbodiimide group and a carbodiimide group-containing compound (b); (ii) comprising carbodiimide groups in an amount of 0.1 to 50 mmol per 100 g of adhesive composition; and (iii) having a density of 0.870 g/cm.sup.3 to 0.940 g/cm.sup.3.

Description

EXAMPLE

[0097] Hereinafter, the present invention will be described more specifically by way of Examples and Comparative Examples, but the present invention is not limited to these Examples as long as the gist of the present invention is not exceeded.

[Measuring Methods for Various Properties]

[0098] In Examples and the like, measurements were performed according to the following methods.

[Melt Flow Rate (MFR)]

[0099] Measurement was performed at 230 C. under a load of 2.16 kg according to ASTM D1238.

[Density]

[0100] The density was measured according to JIS K7112.

[Number Average Molecular Weight of Carbodiimide Group-Containing Compound]

[0101] The number average molecular weight of the carbodiimide group-containing compound was measured using GPC (gel permeation chromatography) with a tetrahydrofuran solvent (mobile phase) at a column temperature of 40 C. (in terms of polystyrene, Mw: weight average molecular weight, Mn: number average molecular weight). As standard polystyrene for a molecular weight of 580Mw710.sup.6, polystyrene PS-1 manufactured by Agilent Technologies, Inc. (former Polymer Laboratories Limited) was used.

[Content of Carbodiimide Group]

[0102] The content of the carbodiimide group was calculated from the amount of the carbodiimide group-containing compound used.

[Amount of Maleic Anhydride Grafted]

[0103] The amount of maleic anhydride grafted was determined using FT-IR according to the following method.

[0104] A sample was hot-pressed at 250 C. for 3 minutes to prepare a sheet, and the sheet was then analyzed according to a transmission method using an infrared spectrophotometer (FT-IR 410, manufactured by JASCO Corporation) to obtain an infrared absorption spectrum at around 1790 cm.sup.1. As the analysis condition, the resolution was 2 cm.sup.1, and the number of scans was 32.

[Rate (%) of Reaction Between Polyolefin (a) and Carbodiimide Group-Containing Compound (b)]

[0105] The reaction rate (%) was calculated by the above-described expression (2) from the amounts of maleic anhydride grafted, which were determined by FT-IR on the adhesive composition and the polyolefin (a) (the absorbance due to maleic anhydride (1790 cm.sup.1) in the adhesive composition and the absorbance due to maleic anhydride in the polyolefin (a)).

[Adhesive Strength of Laminate]

[0106] The obtained laminates were each cut out so as to give a sample having a width of 15 mm. The adhesive strength (unit: N/15 mm) at an interface between the polycarbonate layer and the layer formed of the adhesive composition (CDI-PP1) or the adhesive strength (unit: N/15 mm) at an interface between the polycarbonate layer and the MAH-PE layer was measured on the sample using a tension tester by a T-peel method. The measurement was performed in an atmosphere at room temperature, i.e., 23 C., and in an atmosphere at a high temperature, specifically, 100 C. Further, the obtained laminates were each subjected to a retort treatment in hot water at 121 C. for 30 minutes, and the adhesive strength was measured on the resulting laminates in an atmosphere at room temperature in the same manner as described above. The speed of the crosshead was 300 mm/min.

[0107] [Polyolefins Used]

[0108] Polyolefins used in Examples and Comparative Examples are shown below. Commercially available products were used as the polyolefins unless otherwise noted.

[0109] (1) PP-1: polypropylene (random PP, MFR: 7 g/10 min, density: 0.910 g/cm.sup.3, manufactured by Prime Polymer Co., Ltd.)

[0110] (2) PP-2: polypropylene (homo PP, MFR: 3 g/10 min, density: 0.910 g/cm.sup.3, manufactured by Prime Polymer Co., Ltd.)

[0111] (3) MAH-PE: maleic anhydride-modified ethylene/-olefin random copolymer (MFR: 9.0 g/10 min, density: 0.900 g/cm.sup.3, amount of maleic anhydride grafted: 0.2%, manufactured by Mitsui Chemicals, Inc.)

Example 1 and Comparative Example 1

[0112] <Manufacture of Polyolefin (a) Having Group Reactive with Carbodiimide Group>

[0113] With 100 parts by weight of PP-1, 1 part by weight of maleic anhydride (manufactured by Wako Pure Chemical Industries, Ltd.; hereinafter, abbreviated as MAH) and 0.25 parts by weight of 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexyne-3 (trade name PERHEXYN (R) 25B, manufactured by NOF CORPORATION) were mixed, and the resultant mixture was extruded using the twin-screw kneader (TEX-30 manufactured by THE JAPAN STEEL WORKS, LTD., L/D: 40, using vacuum vent) at a cylinder temperature of 220 C., a screw speed of 200 rpm, and a discharge amount of 80 g/min to obtain maleic acid-modified polypropylene (hereinafter, abbreviated as MAH-PP-1). MAH-PP-1 had a density of 0.915 g/cm.sup.3.

[0114] MAH-PP-1 obtained was dissolved in xylene, and the resulting xylene solution was then poured into acetone to reprecipitate MAH-PP-1 for purification. The amount of maleic anhydride grafted was found to be 0.7% by weight as determined by FT-IR.

<Manufacture of Adhesive Composition>

[0115] 90 parts by weight of PP-1, 10 parts by weight of MAH-PP-1 manufactured above, and 1.7 parts by weight of the carbodiimide group-containing compound (trade name CARBODILITE (R) HMV-8CA, manufactured by Nisshinbo Chemical Inc., carbodiimide group equivalent: 278, number average molecular weight: 2100, the number of carbodiimide groups in one molecule: 9) were mixed, and the resultant mixture was extruded using the twin-screw kneader (TEX-30 manufactured by THE JAPAN STEEL WORKS, LTD., L/D=40, using vacuum vent) at a cylinder temperature of 250 C., a screw speed of 200 rpm, and a discharge amount of 80 g/min to manufacture an adhesive composition (hereinafter, abbreviated as CDI-PP1).

[0116] CDI-PP1 obtained had an MFR (230 C., load of 2.16 kg) of 3 g/10 min, and a density of 0.910 g/cm.sup.3. It was found from the FT-IR analysis on CDI-PP1 that a peak (1790 cm.sup.1) assigned to maleic anhydride disappeared, so that the ratio of the difference (X) between the absorbance due to the group reactive with the carbodiimide group in MAH-PP-1 and the absorbance due to the group reactive with the carbodiimide group in CDI-PP1 to the absorbance (Y) due to the group reactive with the carbodiimide group in MAH-PP-1 was 1. Therefore the rate of the reaction between MAH-PP-1 and the carbodiimide group-containing compound was 100%. The content of the carbodiimide group was 6.6 mmol per 100 g of CDI-PP1 (calculated from the amount used).

<Manufacture of Laminates>

[0117] Laminates of PP-2/CDI-PP1/polycarbonate/CDI-PP1/PP-2 as Example 1 and PP-2/MAH-PE/polycarbonate/MAH-PE/PP-2 as Comparative Example 1 were prepared by co-extrusion using a molding machine for molding a five-layered T-die cast sheet consisting of four types of layers (manufactured by EDI). As the polycarbonate, LEXAN: 141R (product name) manufactured by SABIC was used. The extruder for the PP-2 layer had 50 mm, and the temperature thereof was set at 230 C. The extruder for the CDI-PP1 or MAH-PE layer had 40 mm, and the temperature thereof was set at 280 C. The extruder for the polycarbonate layer had 30 mm, and the temperature thereof was set at 280 C. The temperature at the die was set at 280 C., and the laminate was drawn out at 1 m/min. The thicknesses of the layers were set at 350/100/150/100/350 (m) for both PP-2/CDI-PP1/polycarbonate/CDI-PP1/PP-2 in Example 1 and PP-2/MAH-PE/polycarbonate/MAH-PE/PP-2 in Comparative Example 1.

<Evaluation of Adhesive Strength of Laminates>

[0118] The adhesive strength of each laminate manufactured above was evaluated. The results are shown in Table 1.

TABLE-US-00001 TABLE 1 Comparative Example 1 Example 1 Adhesive In Atmosphere at 26 1 Strength of Room Temperature Laminate (N/15 In Atmosphere at 12 <1 mm) High Temperature After Retort 66 <1 Treatment