Disclosed are catalyst systems, processes for making the catalyst systems, and processes for polymerizing at least one olefin monomer comprising ethylene to form a low-density polyethylene (LDPE). The polymerization process uses a catalyst system that can include: at least one diimine complex having the formula I:

##STR00001##

wherein M is Ni, Pd, or Pt; a first activator such as an organoaluminum compound; and a second activator including a solid oxide chemically-treated with an electron withdrawing anion, such as fluoride silica-alumuina. It was discovered that such the complexes could be activated in a manner to provide an active catalyst system that polymerized ethylene to form a low-density polyethylene (LDPE).

The invention relates to a process for producing a polypropylene composition by sequential polymerization said polypropylene composition having low sealing initiation temperature (SIT) and high melting point (Tm), presenting thus a broad sealing window.

Disclosed is a vinyl alcohol-based block copolymer that is a block copolymer composed of a vinyl alcohol-based polymer block (B-b) and a copolymer block (B-c) comprising a vinyl alcohol-based monomer unit and an acrylic acid-based monomer unit, wherein a content (Z) of the acrylic acid-based monomer unit relative to all monomer units is 0.05 to 20.0 mol %, the block copolymer has a saponification degree of 80 to 99.99 mol %, the block copolymer has a number-average molecular weight (Mn.sub.a) of 20,000 to 440,000, the block copolymer has a molecular weight distribution (Mw.sub.a/Mn.sub.a) of 1.05 to 1.95, and a ratio (DP.sub.b/DP.sub.a) of a number-average polymerization degree (DP.sub.b) of the vinyl alcohol-based polymer block (B-b) to the number-average polymerization degree (DP.sub.a) of the block copolymer is 0.010 to 0.999. The copolymer has a fine balance derived from the copolymer block (B-c) of having a superior solubility in water while being unlikely to undergo thickening or gelation due to pH fluctuation, and also has high mechanic strength derived from the vinyl alcohol-based polymer block (B-b).

Disclosed are catalyst systems, processes for making the catalyst systems, and processes for polymerizing at least one olefin monomer comprising ethylene to form a low-density polyethylene (LDPE). The polymerization process uses a catalyst system that can include: at least one diimine complex having the formula I: ##STR00001##
wherein M is Ni, Pd, or Pt; a first activator such as an organoaluminum compound; and a second activator including a solid oxide chemically-treated with an electron withdrawing anion, such as fluoride silica-alumuina. It was discovered that such the complexes could be activated in a manner to provide an active catalyst system that polymerized ethylene to form a low-density polyethylene (LDPE).

A block copolymer is disclosed. The block copolymer has a structure of formula (V) below:

[D].sub.x-[E].sub.y-[F].sub.z  (V) wherein D, E, and F are each independently a compound of formula (VI) below, and D, E, and F are different from each other; and x, y, and z are each independently an integer from 1 to 40;

##STR00001## wherein A.sub.2 is O or S; R.sub.7 is H or a C.sub.1-6 alkyl; and R.sub.8 is a C.sub.1-12 alkyl, (CH.sub.2).sub.qN(R.sub.11).sub.2, CH.sub.2(CH.sub.2OCH.sub.2).sub.rCH.sub.2N(R.sub.12).sub.2, or CH.sub.2(CH.sub.2OCH.sub.2).sub.sCH.sub.2OR.sub.13, wherein R.sub.11, R.sub.12, and R.sub.13 are each independently a C.sub.1-6 alkyl; and q, r, and s are each independently an integer from 1 to 10.

An oligomerization catalyst, oligomer products, methods for making and using same. The catalyst can include a supported nickel phosphate compound. The catalyst is stable at oligomerization temperatures of 500° C. or higher and particularly useful for making oligomer products containing C4 to C26 olefins having a boiling point in the range of 170° C. to 360° C.

The invention relates to a process for producing a polypropylene composition by sequential polymerization said polypropylene composition having low sealing initiation temperature (SIT) and high melting point (Tm), presenting thus a broad sealing window.

An oligomerization catalyst, oligomer products, methods for making and using same. The catalyst can include a supported nickel phosphate compound. The catalyst is stable at oligomerization temperatures of 500° C. or higher and particularly useful for making oligomer products containing C4 to C26 olefins having a boiling point in the range of 170° C. to 360° C.

A block copolymer and a method for preparing the same are disclosed. The method comprises the following steps: (A) mixing a compound of formula (I), a catalyst of formula (II), and a first solvent to obtain a first mixture; (B) adding a first monomer into the first mixture for reaction to obtain a second mixture; and (C) adding a second monomer into the second mixture for reaction to obtain a third mixture; wherein the compound of formula (I) and the catalyst of formula (II) are as defined in the specification.

An oligomerization catalyst, oligomer products, methods for making and using same. The catalyst can include a supported nickel phosphate compound. The catalyst is stable at oligomerization temperatures of 500° C. or higher and particularly useful for making oligomer products containing C4 to C26 olefins having a boiling point in the range of 170° C. to 360° C.