An extruding unit, a forming roll unit and a thick portion forming mechanism are provided. The extruding unit has an ejecting slit which ejects sheet-shaped molten resin. The ejecting slit includes a standard gap portion and an enlarged gap portion. The standard gap portion is formed as a gap having a constant size. The enlarged gap portion is formed as a gap larger than the standard gap portion in a position corresponding to a thick portion. The thick portion forming mechanism forms one or several thick portions which are thicker than other portion, in the sheet-shaped molten resin continuously in the extrusion direction.

A multilayer film comprising, in this order: (a) a biaxially oriented polyethylene terephthalate layer, (b) a pressure sensitive adhesive layer, (c) an elastic polyurethane dispersion, and (d) a biaxially oriented polyethylene terephthalate layer.

Layer (d) preferably has the structure A:B:A:C; where A and B preferably comprise crystalline PET and antiblocking particles and C is preferably an amorphous, heat-sealable copolyester.

An optically anisotropic polymer thin film includes a crystallizable polymer and an additive configured to interact with the polymer (e.g., via π-π interactions) to facilitate chain alignment and, in some examples, create a higher crystalline content within the polymer thin film. The polymer thin film may be characterized by a bimodal molecular weight distribution where the molecular weight of the additive may be less than approximately 50% of the molecular weight of the crystallizable polymer. Example crystallizable polymers include polyethylene naphthalate, polyethylene terephthalate, polybutylene naphthalate, polybutylene terephthalate, as well as derivatives thereof. Example additives, which may occupy up to approximately 10 wt. % of the polymer thin film, include aromatic ester oligomers, aromatic amide oligomers, and polycyclic aromatic hydrocarbons, for example. The optically anisotropic polymer thin film may be characterized by a refractive index greater than approximately 1.7 and an in-plane birefringence greater than approximately 0.2.

An optically anisotropic polymer thin film includes a crystallizable polymer and an additive configured to interact with the polymer (e.g., via π-π interactions) to facilitate chain alignment and, in some examples, create a higher crystalline content within the polymer thin film. The polymer thin film may be characterized by a bimodal molecular weight distribution where the molecular weight of the additive may be less than approximately 50% of the molecular weight of the crystallizable polymer. Example crystallizable polymers include polyethylene naphthalate, polyethylene terephthalate, polybutylene naphthalate, polybutylene terephthalate, as well as derivatives thereof. Example additives, which may occupy up to approximately 10 wt. % of the polymer thin film, include aromatic ester oligomers, aromatic amide oligomers, and polycyclic aromatic hydrocarbons, for example. The optically anisotropic polymer thin film may be characterized by a refractive index greater than approximately 1.7 and an in-plane birefringence greater than approximately 0.2.

A poly(vinyl acetal) composition, such as a poly(vinyl butyral) composition or resin, can be made containing recycle content by the use of a recycle content aldehyde composition as a feedstock to make the PVA or by application of a recycle allotment, such as an allocation or credit, applied to either the aldehyde composition or to the PVA composition. The recycle content is obtained by cracking a recycle content pyrolysis oil to make a variety of olefins, such as propylene or ethylene.

[Problem] To provide: a biaxially oriented polyester film that exhibits excellent transparency, enables easy secondary processing such as coating and vapor deposition, provides excellent post-secondary-processing properties, and is environmentally friendly in that the film is made from polyester resins recycled from the market and society, including those from PET bottles; and a production method for such a film. [Solution] A biaxially oriented polyester film comprising a polyester resin composition containing particles and polyester resins recycled from the market and society, including those from PET bottles, the film having at least one surface that satisfies all requirements (1)-(3). (1) The number of fine projections having a height less than 3 nm per an area of 4×10-12m2 is 250-600. (2) The number of fine projections having a height not less than 3 nm per an area of 4×10-12m2 is 300-600. (3) The arithmetic average height Sa is 0.01-0.025 μm.

[Problem] To provide: a biaxially oriented polyester film that exhibits excellent transparency, enables easy secondary processing such as coating and vapor deposition, provides excellent post-secondary-processing properties, and is environmentally friendly in that the film is made from polyester resins recycled from the market and society, including those from PET bottles; and a production method for such a film. [Solution] A biaxially oriented polyester film comprising a polyester resin composition containing particles and polyester resins recycled from the market and society, including those from PET bottles, the film having at least one surface that satisfies all requirements (1)-(3). (1) The number of fine projections having a height less than 3 nm per an area of 4×10-12m2 is 250-600. (2) The number of fine projections having a height not less than 3 nm per an area of 4×10-12m2 is 300-600. (3) The arithmetic average height Sa is 0.01-0.025 μm.

Provided is a copolymer which has a mass average molecular weight (Mw) of 240,000 or greater and 3,500,000 or less, a structural unit derived from an acrylate (B1) and a structural unit derived from aromatic vinyl (B2), and a branched structure.

Provided is a copolymer which has a mass average molecular weight (Mw) of 240,000 or greater and 3,500,000 or less, a structural unit derived from an acrylate (B1) and a structural unit derived from aromatic vinyl (B2), and a branched structure.

Described is a mono-axially oriented polyolefin film including a core or base layer containing a plurality of voids formed by a cavitating agent, wherein the film is oriented at least 4 times in the machine direction, and exhibits excellent tear resistance in the transverse direction.