A process or apparatus for producing polyethylene with improved film thinning and handleability involves polymerizing high-pressure ethylene using an autoclave-type reactor in the presence of a polymerization initiator. The reaction zone of the reactor has at least two different temperature sections; the polymerization initiator and the ethylene are supplied to the upstream temperature section in the reaction zone and the ethylene is polymerized to generate polyethylene; unreacted ethylene and the polyethylene generated at the upstream temperature section in the reactor flow into the downstream temperature section in communication with the upstream temperature section, so that additional polyethylene is generated at the downstream temperature section. A difference (T [ C.]) between a temperature (T1 [ C.]) of the temperature section positioned upstream and a temperature (T2 [ C.]) of the temperature section positioned downstream in the reaction zone that receives the polymerization initiator and is in the autoclave-type reactor is 2.1 C. to 8.4 C.

The invention relates to a process for the preparation of low density polyethylene (LDPE) wherein the polymerisation takes place in a tubular reactor at peak temperatures ranging from 180 C. to 350 C. and at pressures ranging from 150 to 350 MPa and wherein the total effective length of the polymerisation reactor divided by the number of reaction zones is in the range from 230 to 350 m.

The invention relates to a process for the preparation of low density polyethylene (LDPE) wherein the polymerisation takes place in a tubular reactor at peak temperatures ranging from 180 C. to 350 C. and at pressures ranging from 150 to 350 MPa and wherein the total effective length of the polymerisation reactor divided by the number of reaction zones is in the range from 230 to 350 m.

The present invention provides a surface treatment film that is capable of imparting durability such as wear resistance, friction resistance, chemical resistance, heat resistance, and solvent resistance to the surfaces of various substrates, and that exhibits excellent adhesion to the surfaces of the substrates. The surface treatment film is provided on the surface of a substrate. The surface treatment film has a laminated structure that includes a polymer layer (i) disposed on the surface side of the substrate and a polymer layer (ii) disposed on the polymer layer (i). The polymer layer (i) contains a first polymer derived from a polymerization initiation group-containing polymer, such as a polyester having, in a side chain, a functional group represented by formula (1) wherein R.sub.1 represents a hydrogen atom, a methyl group, or the like, R.sub.2 represents a methyl group or the like, X represents a chlorine atom or the like, Y represents O or NH, and * shows a bonding position. The polymer layer (ii) contains a second polymer which contains a constituent unit derived from a monomer such as an aromatic vinyl-based monomer and which extends using the functional group represented by formula (i) as a polymerization initiation point.

A method for producing an ethylene-acrylic acid copolymer may minimize the neck-in phenomenon of the strand by discharging the copolymer strand by controlling the discharging temperature of the produced copolymer to be 200 to 300 C., has excellent workability, processability, and moldability, and melt index (MI) is easy to control. In addition, the ethylene-acrylic acid copolymer produced by this method has the effect of having high melt tension.

An olefin-based polymer has an S value of 0.60 or more. The S value is calculated using formula (i):

[00001]$\left[\mathrm{Formula}1\right]$$\begin{array}{cc}S=\frac{y-\mathrm{value}\mathrm{at}\mathrm{GA}-y-\mathrm{value}\mathrm{at}\mathrm{LA}\min }{x-\mathrm{value}\mathrm{at}\mathrm{GA}-x-\mathrm{value}\mathrm{at}\mathrm{LA}\min }/T& \left(i\right)\end{array}$

LA min is a minimum at lowest x, and LA max is a minimum at highest x on a first derivative curve obtained by a Savitzky-Golay method from a molecular weight distribution curve where an x-axis represents a log value (log A) of a molecular size (A) determined by gel permeation chromatography and a y-axis represents a polymer concentration fraction (dW/d log A) against the log value. GA is a point at a highest y in a range of an x-value at LA min or more and an x-value at LA max or less, and T is an area of the molecular weight distribution curve.

Embodiments of the present disclosure are directed to methods for producing ethylene acid copolymer comprising: polymerizing via free-radical polymerization at a pressure of at least 1000 atmospheres (atm) an ethylene monomer and unsaturated carboxylic acid containing comonomer to produce the ethylene acid copolymer, wherein the ethylene monomer and unsaturated carboxylic acid containing comonomer are in a mixture comprising at least one saturated carboxylic acid cosolvent, and wherein the at least one saturated carboxylic acid cosolvent having a boiling point less than 237 C. at 1 atm pressure and is present in the mixture at an amount of 1 to 25 wt. %.

An ethylene-based polymer comprising from 0.01 to 25 wt. % of at least one terpene comonomer and a method for producing an ethylene-based polymer under a high-pressure system. The present invention further relates to extrusion coating film applications.

The disclosure provides methods for removing polymeric fouling on process equipment during low density polyethylene manufacture. A purge cleaning composition with ethylene gas containing at least one C3+ hydrocarbon alkene for a period of time is used to remove polymer build-up in at least one location in the polymerization plant, such as, without limitation, the reactor or in tubing between a reactor and a pre-heater or between a cooler and a preheater.

A method for preparing an ethylene-polar monomer copolymer is disclosed. The method contains: providing at least one tank reactor and a tubular reaction system containing at least one tubular reactor; contacting ethylene, a polar monomer, and an organic peroxide and carrying out a polymerization reaction in the tank reactor and the tubular reactor under conditions including a pressure of 100-400 MPa and a temperature of 120-350 C. to prepare the ethylene-polar monomer copolymer. Also disclosed is a device for preparing an ethylene-polar monomer copolymer.