JPS61248736A - Cellulose ester film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a cellulose ester film. More specifically, the purpose is to improve the deterioration of mechanical properties and dimensional changes that occur when a cellulose ester film is left at high temperature and high humidity for a long time.

(Conventional technology Cellulose ester film has a brightness of f<'h and a film with small refractive index anisotropy can be easily produced, so it is widely used in optical applications such as a protective film for polarizing films. It is used.

However, one drawback of cellulose ester film is that if it is left in a high temperature and high humidity atmosphere for a long time, the ester will undergo hydrolysis, and if the film progresses further, the main chain will break and the mechanical properties will deteriorate, resulting in large dimensional changes. cause something.

A polarizing plate is generally made by dipping a polyvinyl alcohol film in an aqueous solution of iodine and potassium iodide, then stretching it uniaxially by a factor of 3 to 4 c to form a polarizing film, which is then coated with cellulose triacetate (TAC) as a retentive film. It is made by laminating cellulose ester on both sides with adhesive.

If this polarizing plate is left in a high temperature and high humidity atmosphere, the cellulose ester may be hydrolyzed and the polarizing plate may no longer function properly. Therefore, it is recommended to use polyester instead of cellulose ester (for example, JP-A-5R-trio
s, using JP-A Sho SR-TA 170 tan or polyacrylic polymer (for example, JP-A SHO J TA ! 20 R)
r1e lyamide-epoxy resin (e.g. JP-A-Sho! Hiro-/
Although the use of JJ3 (t) is being considered,
They do not always have sufficient durability or are inferior to cellulose esters in terms of optical performance, so it has not been possible to obtain a fully satisfactory product.

(Object of the Invention) The object of the present invention is to prevent deterioration of mechanical strength and reduce dimensional changes in a high-temperature, high-humidity atmosphere without impairing the excellent optical properties of cellulose ester films.

(Disclosure of the Invention) According to the present invention, it has been found that the above object can be achieved by providing a layer of a chlorine-containing vinyl polymer having a chlorine content of 100% or more on both or one side of a cellulose ester film.

The cellulose ester film of the present invention includes cellulose triacetate, cellulose diacetate, cellulose propionate, cellulose acetate butyrate,
Cellulose acetate propionate, etc. can be listed, but the most preferred are cellulose triacetate,
and cellulose acetate.

As a chlorine-containing vinyl polymer, the chlorine content is 6 by weight.
Polymers having a fraction of ujwtTo or more include, for example, vinylidene chloride-containing polymers, vinyl chloride-containing polymers, chlorinated polyethylene, chlorinated polypropylene, and the like. Among these, vinylidene chloride-containing polymers are particularly effective.

Examples of vinylidene chloride-containing polymers include vinylidene chloride homopolymers, copolymers of vinylidene chloride and acrylonitrile (vinylidene chloride containing t!mol or more), and copolymers of vinylidene chloride and methacrylate or methyl methacrylate (vinylidene chloride 91 fufu 0%). Examples of vinyl chloride-containing polymers include vinyl chloride homopolymers, vinyl chloride and acrylonitrile copolymers ( vinyl chloride r
! copolymer of vinyl chloride and methyl acrylate or methyl methacrylate (contains more than 0 moles of vinyl chloride), copolymer of vinyl chloride and vinyl acetate (contains more than 20 moles of vinyl chloride), These include copolymers of vinyl chloride and maleic anhydride (containing more than O mole of vinyl chloride). For chlorinated polyethylene and chlorinated polypropylene, the chlorine content is ≠ by weight! Contains more than 100%.

To give a more specific example, examples of vinyl chloride-17dene-containing polymers include Saran from Asahi Dow Co., Ltd. and Tare-Takuron from Kureha Kagaku Co., Ltd.

Examples of vinyl chloride-containing polymers include Nisrex manufactured by Sekisui Chemical Co., Ltd., Denki Kagaku Resin manufactured by Denki Kagaku Kogyo Co., Ltd., Zeon Resin manufactured by Nippon Zeon Co., Ltd., and Tinlit Resin manufactured by Order Kagaku Co., Ltd., among others. Examples of chlorinated polyethylene and chlorinated polypropylene include Super Chron manufactured by Chongyang Kokusaku Pulp Co., Ltd. In the case of the present invention, the main objective is to provide moisture resistance, so a uniform film of chlorine-containing polymer is applied to the cellulose ester film. It is important that the formation of Therefore, it is desirable to apply a uniform liquid solution rather than applying a water-dispersible latex. In the case of latex, polymers containing chlorine of zOwtLs or more
In general, if the treatment is not carried out at a high temperature (1 JO'C or higher), no film will be formed and a uniform film will not be formed, resulting in insufficient moisture resistance.

On the other hand, if this is treated at high humidity to form a uniform film, the flatness of the cellulose ester film will be impaired and the plasticizer will bleed out, which is not desirable.

To provide a single layer of chlorine-containing polymer on the surface of a cellulose ester film, a solution of the polymer may be applied.

The solvent for the solution may be any solvent that can dissolve the polymer (there are no particular limitations, but examples include acetone, methyl ethyl ketone, methyl isobutyl ketone, ketone solvents such as cyclohenosaran, and ether solvents such as tetrahydrofuran and dionisane). Solvents, ester solvents such as methyl acetate, ethyl acetate, inopropyl acetate, propyl acetate, butyl acetate, aromatic hydrocarbons such as henzene, toluene, xylene, alcohol solvents such as methanol, ethanol, proponol, etc. Can be done.

There is no problem even if a crosslinking agent, ultraviolet absorber, etc. are added to the chlorine-containing polymer layer.

The coating method for providing this layer is not particularly limited, and any commonly used dip coating, roller bead coating, bar code coating, extrusion coating, etc. may be used.

The thickness of a single layer of chlorine-containing polymer is desirably 0.iμ to 10μ, particularly 0.iμ to 10μ. ! If it is thinner than this, the effect of preventing deterioration will be insufficient, and if it is thicker than this, the optical properties of the cellulose ester will be impaired.

The method of using the cellulose ester coated with a single layer of chlorine-containing polymer of the present invention as a protective film for a polarizing film is to laminate the polarizing film with the film of the present invention using an adhesive in the same way as when using a conventional cellulose ester film. do it.

Example 1 A coating solution having the following formulation was applied to both sides of a cellulose triacetate film having a thickness of 20μ to a dry thickness of 1μ, and dried at /λQ0C for 1 minute.

Formulator Vinylidene chloride-acrylonitrile copolymer (copolymerization ratio r:x) Parts by weight Methyl ethyl ketone / co01 Tetrahydrofuran
3Q I Formulation B Chlorinated polyethylene (chlorine content 60%) @ #Methyl ethyl ketone l CoQl Tetrahydrofuran
3゜Formulation C Vinyl chloride-vinyl acetate valve type copolymerization (copolymerization ratio: /) lL1 Methyl ethyl ketone /20 #Tetrahydrofuran
3Q l-formulated vinyl chloride-vinyl acetate valve type combination (copolymerization ratio 6:μ) 4C# methyl ethyl ketone lλQl tetrahydrofuran
30 I Formulation E Polymethyl methacrylate Part by weight Methyl ethyl ketone/CoQl Tetrahydro 7 run
30 I The cellulose triacetate films, which were not coated at all on the coated samples A to F, were left in an atmosphere with a relative humidity of J% for 2Q days, and the tensile strength at break and dimensional changes were measured.

The tensile strength at break should be measured using a Toyo Seiki Tennron (/TM-■) at a tensile speed of 00 nm/min.
Breaking strength of sample after being left to stand Breaking strength of 100% sample]
) to determine the degree of deterioration.

Dimensional changes are measured using a reading microscope to determine the length of the original sample.
) Find the length CI) of the sample after standing (do-1)/
It was determined by loX/00%.

The results were as follows.

Items coated with polymers of higher strength have only slight deterioration.
It was found that the dimensional change was small and it was very effective.

Example 2 A coating solution consisting of the following formulation was applied to both sides of a 10Qμ cellulose triacetate film to a dry thickness of □.

It was applied to a thickness of 7 μm and dried for 1 minute at /200 (:) to produce sample films CF) and (G).

Formulation F Hynylidene chloride acrylonitrile copolymer (copolymerization ratio P2/) Part by weight: Tetrahydrofuran! Ol methyl ethyl ketone
100 #Formulation G Vinyl chloride-vinyl acetate valve type copolymer (copolymerization ratio, j: 0゜j) μ I tetrahydrofuran jOl methyl ethyl ketone
100# The above film λ type and three types of uncoated cellulose triacetate films were used as protective films, and a polarizing film prepared by the following method was adhered with an adhesive to prepare a polarizing plate.

How to make polarizing film Thickness/20μ polyvinyl alcohol film with 1 iodine
The film was immersed in an aqueous solution containing 2% by weight of potassium iodide and 2% by weight of boric acid, and stretched at 600 cm to μ times the polarizing film.

Place the above polarizing plate in a ROOC atmosphere with a relative humidity of 5%.
The sample was left for j days and its dimensional change was measured.

2.5% for those using sample (F), 2.5% for those using sample (F);
The film using G) showed a shrinkage of λ, t%, whereas the film using an uncoated cellulose triacetate film showed a large shrinkage of 5%.

Claims (1)

[Claims] A cellulose ester film characterized in that a vinyl polymer containing at least 45% by weight of chlorine is coated on at least one side of the cellulose ester film.