Polylactic acid film and preparation method thereof

A technology of polylactic acid and polylactic acid copolymer, which is applied in the field of polylactic acid film and its preparation, can solve the problems of reducing film value and aesthetic appeal, affecting the ability to display packaging products, and increasing the cost of anti-blocking particles, so as to achieve the source of raw materials Very environmentally friendly, rich sources of raw materials, excellent haze and gloss values

Inactive Publication Date: 2019-09-24
梁真
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, its use has several disadvantages: most of the benefits provided by the particles are lost due to their incorporation inside the film away from the surface; larger quantities of anti-blocking particles must be used than required to improve the surface properties, which leads to The cost increases and will limit the use of expensive but highly effective additives, such as spherical cross-linked silicone resins, such as Tospearl.TM., or cross-linked acrylic spheres, such as Epostar.TM.; use additional non-functional Reactive particles will increase the amount of light scattering as measured by film haze and reduce the value and aesthetic appeal of the film and affect the ability to display the packaged product
[0011] Although the preparation of cellulose film has been realized at present, the film prepared by it has the disadvantages of poor stretchability, easy damage, high rejection rate, etc., and there is no report that cellulose and chitin can be used to prepare film together

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0063] Five-ply films were prepared by extruding the main or inner layer (core layer) of PLA4042.TM. separately. On this core layer, extrude two other surface layers of PLA4042.TM, each layer containing 0.2 wt% spherical particle surface layer prepared by cross-linked polymethylsilsesquioxane, with an average particle size of 2.0 μm ( Tospearl.TM.120A), the thickness of the final surface layer after stretching is 0.8-1.4 μm, and the above-mentioned inner layer and surface layer are prepared for later use.

[0064] Wherein the preparation method of intermediate layer is as follows:

[0065] Take the dry wood cellulose, grind it into granules, and pass through a 30-mesh sieve; mix the cellulose and glycerin at a solid-to-liquid ratio (g / mL) of 1:5, and heat and swell in an oil bath at 110°C for 2 hours; Add 0.25% sulfuric acid relative to the total mass of the system to the swollen cellulose; heat and swell the mixture in an oil bath at 90°C for 2 hours and mechanically stir at...

Embodiment 2

[0069] A film was prepared as in Example 1, except that the anti-blocking particles contained 0.05-2.5% by weight of the surface layer of silica particles with an average particle size of 4-5 μm. The films so produced showed improved handling and blocking resistance, but poor clarity due to objectionably high haze levels. It did not improve in reducing static electricity generation and reducing dust absorption, but its gas barrier performance was superior.

Embodiment 3

[0071] A film was prepared as in Example 1, wherein both skin layers consisted of a heat-sealable PLA 4060 copolymer and contained 0.2% by weight of a skin layer of spherical particles made of crosslinked polymethylsilsesquioxane. The films thus produced exhibit improved heat sealability and exhibit excellent handling and winding properties while maintaining excellent optical clarity and surprisingly low static generation and dust pick-up tendencies and gas barrier properties.

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Abstract

The invention relates to a polylactic acid film. The polylactic acid film comprises an inner layer prepared from a polylactic acid copolymer, at least one middle layer mainly prepared from cellulose and chitin, and at least one surface layer prepared from a polylactic acid copolymer; and based on a weight of the surface layer, the surface layer contains 0.05%-0.6% by weight of crosslinked polymer spherical particles having particle diameters of 2-6 [mu]m, and the middle layer is located between the inner layer and the surface layer. The invention also relates to a preparation method of the polylactic acid film. The preparation method comprises the steps of performing co-extrusion cast compounding on the inner layer, the middle layer and the surface layer, and performing biaxial stretching to obtain the polylactic acid film. According to the multi-layer co-extruded film containing the polylactic acid polymer and the cellulose-chitin prepared by the invention, the friction coefficient is reduced, the adhesion is reduced, the heat sealing property is increased, electrostatic formation and film dust collection are reduced, the film has high biodegradability, the cellulose-chitin layer has a crystal structure through which gas cannot pass, the crystal structure can effectively resist invasion of oxygen, and the prepared film is more suitable as a packaging film for fresh food.

Description

technical field [0001] The invention belongs to the technical field of film preparation, and in particular relates to a polylactic acid film and a preparation method thereof. Background technique [0002] Polylactic acid is a biodegradable or compostable polymer produced by the polycondensation of lactic acid. The monomer used to produce polylactic acid has two optically active isomers, namely D-lactic acid and L-lactic acid. When the two isomers are combined and polymerized, their relative amounts produce a variety of polymers with varying degrees of crystallinity (amorphous to semi-crystalline), crystallization behavior, and melting points. Polymers of this type are available from Cargill-Dow and representative commercially available polymer grades are PLA4042.TM. and PLA4060.TM. Both resins were prepared by combining different ratios of two optical isomers of lactic acid, L-lactic acid and D-lactic acid. The relative proportions of the two isomers control the final cry...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08J5/18C08L67/04C08L83/04C08L97/02C08L5/08C08L1/04C08L1/02B32B9/02B32B9/04B32B27/18B32B27/36B29D7/01
CPCB29D7/01B32B9/02B32B9/045B32B27/18B32B27/36B32B2255/10B32B2255/205B32B2264/0214B32B2264/025B32B2264/12B32B2307/31B32B2307/54B32B2307/7163B32B2307/7242B32B2317/18B32B2367/00C08J5/18C08J2301/02C08J2301/04C08J2367/04C08J2397/02C08J2405/08C08J2483/04
Inventor 梁真
Owner 梁真
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