Mitsubishi Monsanto Chemical Co., Ltd.

Tsuguo Okumura

Kenji Mori

Naomichi Yamagishi

Kazuharu Abe

Hitoshi Matsuda

Masayoshi Sugiyama

Shinichi Ohashi

Kazuhisa Miyashita

Tatsufumi Hiratsuka

A thermoplastic sheet is prepared by (i) extruding a molten thermoplastic resin in the form of a sheet from a molding die; (ii) applying static charges to the extruded resin sheet from a first electrode whereby the charged resin sheet is pinned to the surface of an electrical insulating layer of a quenching roller to quench the resin sheet; (iii) peeling the quenched sheet from the surface of the quenching roller; and (v) applying electrostatic charges having a reverse polarity to that of the electrostatic charges from the first electrode to the exposed surface portion of the quenching roller from a second electrode. The quenching roller is made of an electrically earthed substrate and the electrical insulating layer formed on the surface of the substrate. The second electrode is made of a plurality of electrodes arranged at intervals along the rotating direction of the quenching roller between the sheet-peeling position where the quenched sheet is peeled from the quenching roller and the sheet pinning-initiating position where the sheet to be quenched is pinned to the quenching roller, and the electrical insulating layer has a volume resistance and surface resistance of at least 10.sup.7 .OMEGA. and a surface roughness not larger than 0.3 .mu.m expressed as the center line average roughness (Ra).

Process for preparation of thermoplastic resin sheets

Disclosed is a heat-shrinkable biaxially drawn polyamide film which is formed from a homopolymer or copolymer of .epsilon.-caprolactam or a polyblend thereof, by a sequential biaxial drawing method and which has a density of 1.129 to 1.136 g/cm.sup.3 and an in-plane orientation index of 0.0535 to 0.0580. This film is prepared by the steps of drawing in the machine direction a substantially amorphous unoriented polyamide film at 45.degree. to 65.degree. C., a deformation rate of at least 10,000%/min and a draw ratio of 2.7 to 3.5 by a roll type longitudinal drawing method, gripping the ends of the film by tenter clips, drawing the film in the transverse direction at a film temperature not higher than 100.degree. C., an average deformation rate of 2,000 to 10,000%/min and a draw ratio of 3 to 5, and heat-treating the film at 125.degree. to 170.degree. C. while gripping the ends of the film by the tenter clips.

Heat-shrinkable biaxially drawn polyamide film and process for

Biaxially drawn polyamide films having an excellent levelness are prepared as follows. A substantially unoriented polyamide film is heated at 45.degree.-65.degree. C., and then drawn in the longitudinal direction at a deformation rate of at least 10,000%/min. and a draw ratio of 2.7-3.5 by a roll stretcher. The drawn film is immediately transferred to the lateral drawing position at 45.degree.-60.degree. C. within a time (t):t=e.sup.(3.9-0.053T.sbsp.1.sup.) where e=the base of natural logarithm and T.sub.1 =film temperature during this period of time (t), which is 45.degree.-60.degree. C. The thickness profile of the film at the starting position of lateral drawing is gradually reduced from the side and portions toward the central portion of the width so that the film thickness at the central portion is 75-90% of the film thickness at the side end portions. The film is drawn in the lateral direction at an average deformation rate of 2,000-10,000%/min. and a draw ratio of 3-5 by a tenter type stretcher in such a manner that, until the mechanically set draw ratio between respective tenter clips exceeds 1.4 times the original distance, the film is expanded at an angle of up to 6.degree. with respect to the travelling direction at a tenter clip temperature T.sub.2 (T.sub.2 &lt;T.sub.1). The film temperature is elevated stepwise in the lateral drawing and the film temperature at the termination position of lateral drawing is 70.degree.-100.degree. C.

Process for preparing biaxially drawn polyamide films

A biaxially drawn laminated films having a good oxygen barrier property, a good mechanical strength and high thickness uniformity are made by a process comprising:

Biaxially drawn laminated films prepared by sequential stretching

A broad and continuous sheet or film is uniformly heated in a highly precise manner and with a specific heat profile by using a plurality of radiation heating furnaces, wherein in the interior of each radiation heating furnace, a plurality of rows of heaters are arranged rectangularly to the direction of delivery of the sheet or film to be heated. A thermometer for measuring the temperature of the sheet or film is arranged in the vicinity of an outlet for the sheet or film outside each radiation heating furnace. Outputs of heaters arranged within the radiation heating furnaces located just before the respective thermometers are controlled based on the temperatures detected by the respective thermometers by using a computer.

Growing community of inventors

Ibaraki, Japan

Tsuguo Okumura