Provided are an active energy ray-curable composition that has good antistatic properties, scratch resistance, and transparency after curing, and an antistatic film using the same. The active energy ray-curable composition of the present invention is an active energy ray-curable composition, including a photopolymerization initiator A represented by the following Formula (I), an antistatic polymer B, and a polymerizable compound C containing an ethylenically unsaturated group, ##STR00001## in Formula (I), V.sup.1, V.sup.2, V.sup.3, and V.sup.4 each independently represent a hydrogen atom or a substituent, and n represents an integer of 1 to 5.

The present invention relates to an additive composition for controlling and inhibiting polymerization of monomers, wherein the composition comprises a combination of (a) a phenol compound comprising catechol compound with (b1) an aliphatic tertiary amine, (b2) oxide treated derivative of the aliphatic tertiary amine, or (b2) a mixture thereof, wherein the aliphatic tertiary amine contains one or more hydroxyl groups in the alkyl chain of the aliphatic tertiary amine. In one embodiment, the present invention also relates to a method for controlling and inhibiting polymerization of monomers by employing the additive composition of the present invention. In another embodiment, the present invention also relates to a method of using the additive composition of the present invention for controlling and inhibiting polymerization of monomers. In another embodiment, the present invention also relates to methods for controlling and inhibiting polymerization of monomers in a primary fractionator (or an ethylene plant), and for operating a primary fractionator, and for reducing fouling and polymer deposits in a primary fractionator, and to extend a run-length of a primary fractionator or of an ethylene plant.

Systems and processes for controlling fouling in the manufacture of ethylene polymers and copolymers at high pressure. Disclosed is a high pressure polyethylene polymerization system comprising a reactor, a primary compressor, and a secondary compressor, the secondary compressor comprising: a) a first stage, wherein the first stage comprises at least two cylinders, and the discharge pipes of the at least two cylinders are fluidly connected by a first stage discharge cross-connect pipe; b) a second stage; c) an interstage; and d) a first cooler applied to the interstage piping starting at a location within 10 meters downstream of the first stage discharge cross-connect pipe.

Systems and processes for controlling fouling in the manufacture of ethylene polymers and copolymers at high pressure. Disclosed is a high pressure polyethylene polymerization system comprising a reactor, a primary compressor, and a secondary compressor, the secondary compressor comprising: a) a first stage, wherein the first stage comprises at least two cylinders, and the discharge pipes of the at least two cylinders are fluidly connected by a first stage discharge cross-connect pipe; b) a second stage; c) an interstage; and d) a first cooler applied to the interstage piping starting at a location within 10 meters downstream of the first stage discharge cross-connect pipe.

A fluid is fed into a polymer bed of a fluidized bed gas phase polymerization reactor by introducing the fluid into the polymer bed through a distributor protruding into the fluidized bed zone of the reactor and terminating with a discharge end positioned so that the following equation is fulfilled:

d/D>0.002

wherein d is the distance of the distributor's discharge end from the wall of the reactor, and D is the diameter of the reactor in the fluidized bed zone.

A fluid is fed into a polymer bed of a fluidized bed gas phase polymerization reactor by introducing the fluid into the polymer bed through a distributor protruding into the fluidized bed zone of the reactor and terminating with a discharge end positioned so that the following equation is fulfilled:

d/D>0.002

wherein d is the distance of the distributor's discharge end from the wall of the reactor, and D is the diameter of the reactor in the fluidized bed zone.

A method of minimizing popcorn polymer seed formation, the method adding a treatment composition to a monomer containing system. A method for inhibiting popcorn polymer growth, the method adding a treatment composition to a monomer containing system, wherein the treatment composition comprises a quinone methide, a quinone methide derivative, or a quinone methide analogue based compound, and wherein the system comprises popcorn seed or polymer.

A polyethylene for a pipe and a joint of the present invention satisfies the following characteristics (1) to (5): Characteristic (1): a melt flow rate at a temperature of 190 C. and a load of 21.6 kg (HLMFR) is 5 to 20 g/10 minutes, Characteristic (2): a density (D) is 0.954 to 0.960 g/cm.sup.3, Characteristic (3): a ratio of weight-average molecular weight (Mw) and number-average molecular weight (Mn) (Mw/Mn) measured by gel permeation chromatography (GPC) is 15 to 27, Characteristic (4): a rupture time at 80 C. and 5 MPa by a full notch creep test (FNCT) is 150 hours or more, and Characteristic (5): a Charpy impact strength (CIS) measured at 20 C. is 8.5 kJ/m.sup.2 or more.

A polyethylene for a pipe and a joint of the present invention satisfies the following characteristics (1) to (5): Characteristic (1): a melt flow rate at a temperature of 190 C. and a load of 21.6 kg (HLMFR) is 5 to 20 g/10 minutes, Characteristic (2): a density (D) is 0.954 to 0.960 g/cm.sup.3, Characteristic (3): a ratio of weight-average molecular weight (Mw) and number-average molecular weight (Mn) (Mw/Mn) measured by gel permeation chromatography (GPC) is 15 to 27, Characteristic (4): a rupture time at 80 C. and 5 MPa by a full notch creep test (FNCT) is 150 hours or more, and Characteristic (5): a Charpy impact strength (CIS) measured at 20 C. is 8.5 kJ/m.sup.2 or more.

The present disclosure relates to a continuous process for the preparation of ethylene homopolymers or ethylene copolymers comprising polymerizing ethylene or copolymerizing ethylene and one or more other olefins in the presence of a chromium catalyst in a gas-phase polymerization reactor which is equipped with a cycle gas line for withdrawing reactor gas from the reactor, leading the reactor gas through a heat-exchanger for cooling and feeding the reactor gas back to the reactor, wherein the polymerization is carried out at a temperature from 30? C. to 130? C. and a pressure of from 0.1 to 10 MPa and an aliphatic carboxylic acid ester having from 8 to 24 carbon atoms is added.