An ethylene copolymer comprising ethylene and at least one alpha olefin having from 4 to 8 carbon atoms has a density f from 0.940 to 0.960 g/cm.sup.3, a molecular weight distribution, Mw/Mn of from 9 to 12, and a Z-average molecular weight, Mz of greater than 500,000. The ethylene copolymer is made in a multi-zone reactor system under solution phase polymerization conditions and is useful in the preparation of biaxially oriented polyethylene (BOPE) films.

A copolyester, comprising structural units represented by [I], [II], [III] and [IV]. The number of structural units represented by [III] is 1-99% of the number of structural units represented by [I], and the number of structural units represented by [IV] is 0-99% of the number of structural units represented by [I]. Also provided are a preparation method therefor and an application thereof. Because an introduced high-temperature self-crosslinking group and an ion group can improve the melt viscosity and the melt intensity during burning of a copolyester, and effectively enhance the char-forming capability of the copolyester, the copolyester exhibits excellent flame retardance and anti-dripping performance. The preparation process for the copolyester is mature, convenient to operate, and easy to control and apply to industrial production.

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A copolyester, comprising structural units represented by [I], [II], [III] and [IV]. The number of structural units represented by [III] is 1-99% of the number of structural units represented by [I], and the number of structural units represented by [IV] is 0-99% of the number of structural units represented by [I]. Also provided are a preparation method therefor and an application thereof. Because an introduced high-temperature self-crosslinking group and an ion group can improve the melt viscosity and the melt intensity during burning of a copolyester, and effectively enhance the char-forming capability of the copolyester, the copolyester exhibits excellent flame retardance and anti-dripping performance. The preparation process for the copolyester is mature, convenient to operate, and easy to control and apply to industrial production.

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Provided is a biaxially oriented polypropylene film that has high stiffness and can easily retain a bag shape when made into a packaging bag even if the film is made thinner, and at the same time, that can maintain water vapor barrier properties even if the film is made thinner, and has few wrinkles in and around the sealed portion when heat-sealed to make a packaging body. The biaxially oriented polypropylene film satisfies the following (1) and (2): (1) a half width of a peak derived from an oriented crystal in a width direction in angular dependency of a (110) plane of polypropyleneα-type crystal obtained by wide-angle X-ray diffraction measurement is 26° or smaller; (2) the ratio of (III) to the total of a crystalline component (I), a restrained amorphous component (II), and an unrestrained amorphous component (III) classified by pulse NMR according to solid-echo method is 7% or lower.

Provided is a biaxially oriented polypropylene film that has high stiffness and can easily retain a bag shape when made into a packaging bag even if the film is made thinner, and at the same time, that can maintain water vapor barrier properties even if the film is made thinner, and has few wrinkles in and around the sealed portion when heat-sealed to make a packaging body. The biaxially oriented polypropylene film satisfies the following (1) and (2): (1) a half width of a peak derived from an oriented crystal in a width direction in angular dependency of a (110) plane of polypropyleneα-type crystal obtained by wide-angle X-ray diffraction measurement is 26° or smaller; (2) the ratio of (III) to the total of a crystalline component (I), a restrained amorphous component (II), and an unrestrained amorphous component (III) classified by pulse NMR according to solid-echo method is 7% or lower.

Provides is a resin film containing a poly(3-hydroxyalkanoate) resin component. A tensile modulus of the resin film is from 500 to 2000 MPa. A swelling degree of the resin film, as measured by immersion of the resin film in methyl ethyl ketone for two hours, is from 1 to 5. Preferably, the poly(3-hydroxyalkanoate) resin component is a mixture of at least two poly(3-hydroxyalkanoate) resins differing in types and/or contents of constituent monomers.

Provides is a resin film containing a poly(3-hydroxyalkanoate) resin component. A tensile modulus of the resin film is from 500 to 2000 MPa. A swelling degree of the resin film, as measured by immersion of the resin film in methyl ethyl ketone for two hours, is from 1 to 5. Preferably, the poly(3-hydroxyalkanoate) resin component is a mixture of at least two poly(3-hydroxyalkanoate) resins differing in types and/or contents of constituent monomers.

The present invention relates to an aqueous barrier coating composition comprising: 50-99.9% by weight of one or more anionic low molecular weight polysaccharide(s) having a degree of polymerization (DP) in the range of 2-12; 0.1-10% by weight of a polycationic polymer; based on the total dry weight of the aqueous barrier coating composition.

An optical film is provided in which a wavelength dispersion characteristic at a wavelength of 400 nm to 800 nm satisfies the following general formula (1):

[00001]$\begin{array}{cc}\frac{\Delta \lambda }{\Delta 550}=a{\lambda }^{-b}& \left(1\right)\end{array}$

wherein a has a value of 1500<a<6600, b has a value of 1.17<b<1.27, Δλ represents a photoelastic coefficient at an arbitrary wavelength λ nm in a range of 400 nm to 800 nm, and Δ550 represents a photoelastic coefficient at a wavelength of 550 nm and which has a thickness of 10 m to 1000 m, can be provided.

An optical film is provided in which a wavelength dispersion characteristic at a wavelength of 400 nm to 800 nm satisfies the following general formula (1):

[00001]$\begin{array}{cc}\frac{\Delta \lambda }{\Delta 550}=a{\lambda }^{-b}& \left(1\right)\end{array}$

wherein a has a value of 1500<a<6600, b has a value of 1.17<b<1.27, Δλ represents a photoelastic coefficient at an arbitrary wavelength λ nm in a range of 400 nm to 800 nm, and Δ550 represents a photoelastic coefficient at a wavelength of 550 nm and which has a thickness of 10 m to 1000 m, can be provided.