JPS6220224B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a film that exhibits transparency and non-optically active properties, and more particularly relates to a non-optically active film that exhibits good properties in terms of heat resistance, Young's modulus, and flexibility. It is something.

If we summarize the films that have been used in the past from the viewpoint of materials, we have found the following problems.

Polycarbonate film: In addition to poor chemical resistance, it is difficult to make into a thin film and is brittle.

Polyethylene terephthalate film: It has relatively good flexibility, but its transparency is extremely poor, and its chemical resistance and heat resistance are insufficient.

Polystyrene film: The material is brittle and has extremely low flexibility, making it difficult to make into a thin film, and it also has insufficient chemical and heat resistance.

Polymethyl methacrylate film: Good transparency, but the material itself is brittle and has poor flexibility. It also has poor heat resistance and has the same problem.

Cellulosic film: It has poor chemical resistance and heat resistance, and also causes strength problems when finished as a thin film. It also has poor moisture resistance.

The present invention has been made to overcome these drawbacks of the prior art, and aims to provide a film that is excellent in non-optical rotation, heat resistance, flexibility, and Young's modulus.

That is, the non-optically active film of the present invention has the general formula (In the formula, R ¹ to ^{R 6} are each hydrogen or carbon number 1 to 3
^R7 is a lower alkyl group having 2 to 4 carbon atoms, m is an integer of 0 to 3, and n is an integer of 20 to 300) This is a crosslinked non-optically rotating film formed from a phenoxy ether type crosslinked polymer by crosslinking the hydrogen moiety with a polyfunctional compound.

In the above general formula, examples of the lower alkyl group having 1 to 3 carbon atoms represented by R ¹ to R ⁶ include saturated lower alkyl groups such as ^methyl , ethyl, propyl, and isopropyl; Examples of the lower alkylene group of 4 include ethylene, propylene, trimethylene, and butylene. The phenoxy ether type polymer shown above is a known polymer per se, and has the general formula It is obtained by condensing epichlorohydrin with bisphenol A or an analog thereof represented by the formula (wherein R ¹ to ^{R 7} and m have the same meanings as above).

In the present invention, the above phenoxy ether type polymer is used as a crosslinked polymer in which the active hydrogen moiety, specifically the hydrogen moiety of the hydroxyl group, is subjected to a crosslinking reaction with a polyfunctional compound. Such polyfunctional compounds include groups with high reaction activity with hydroxyl groups, such as isocyanato groups, carboxy groups, reactive inducing groups in carboxy groups (such as halides, activated amides, active esters, acid anhydride groups, etc.); Examples include compounds having two or more of the same or different mercapto groups, specifically tolylene diisocyanate, m
- Polyisocyanates such as phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate and their polyhydric alcohol adducts; blocked polyisocyanates such as phenol blocked tolylene diisocyanate; adipic acid, tartaric acid , polyhydric carboxylic acids such as sebacic acid, phthalic acid, and reactive derivatives at the carboxy group; mercapto-substituted organic carboxylic acids such as thioglycolic acid; etc., as well as epichlorohydrin, sodium thiosulfate, melamine-formaldehyde, phenolic resin, urea- Formaldehyde resin or the like can also be used. In the present invention, compounds having an isocyanato group are particularly preferred.

In the present invention, non-optical rotation property means that when the film is placed between a pair of mutually orthogonal polarizing films, neither the brightness nor the hue of the orthogonal polarizing films change even if the film is rotated. , and the retardation value (R
If the value) is 100 mμ or less, preferably 30 mμ or less, it indicates non-optical rotation. Note that the R value is expressed as the product of the thickness d of the film and the absolute value |n ₁ -n ₂ | of the difference between two refractive indices in the direction perpendicular to the film.

R=d | n ₁ - _{n 2} | where n ₁ is the refractive index in an arbitrary direction, n ₂ is the refractive index in the direction orthogonal to the n ₁ direction. Next, in order to obtain the non-optically rotating film of the present invention, Any known method or method to be developed in the future may be used to form the composite film, but in order to satisfy non-optical rotation, transparency, surface uniformity, etc., the casting method is recommended. suitable. Regarding non-optical rotation, it is not a problem to have some optical rotation as long as it does not pose a problem in practice.
Since the above-mentioned crosslinking reaction is usually carried out during or after film formation, it is desirable that the solvent used in the casting method be one that can sufficiently dissolve the phenoxy ether type polymer and the crosslinking agent. .
As long as these conditions are satisfied, there are no restrictions on the type of solvent or the adjusted concentration, but representative examples include 1,4-dioxane, dimethylformamide, methyl ethyl ketone, tetrahydrofuran, ethyl carbitol, and butyl carbitol. Examples include toll, butyl carbitol acetate, butyl cellosolve, dimethyl sulfoxide, mesityl oxide, toluene, butanol, and the like.
The concentration of the polymer, etc. is preferably 1 to 80% by weight. In addition, when dissolving the above polymer and crosslinking agent,
The heating conditions should be controlled to such an extent that the crosslinking agent is not deactivated.

The thickness of the film thus formed varies depending on the object to which the film is applied, but is preferably in the range of 4 μm to 2 mm. In other words, if it is less than 4μ, the workability after film formation,
There are difficulties in terms of processability and film strength, and on the other hand, if it exceeds 2 mm, residual strain during film formation becomes large, causing problems in terms of surface uniformity.

The crosslinking reaction is carried out during or after film formation as described above, but preferably occurs after most of the solvent has been evaporated off, and usually proceeds depending on the drying conditions employed during film formation. If a sufficient crosslinking reaction does not proceed under dry conditions, it is recommended that heat treatment be performed as necessary depending on the characteristics of the crosslinking agent. For example, when using a reaction product of phenol and tolylene diisocyanate as a crosslinking agent, it is necessary to add a heat treatment of at least 140° C. for 5 seconds or more.

Since the film thus obtained has both appropriate flexibility and stiffness (high Young's modulus), it has the advantage that it can be made into a thin film without impairing processability or workability. Therefore, it becomes possible to manufacture the film as a long film, which is expected to improve productivity and workability. Moreover, there are no problems in transparency and heat resistance, and it has wide applicability. For example, a transparent conductive film formed by adding a transparent conductive layer to one or both sides of the above film has the characteristics of being thin and flexible, and is particularly suitable for large liquid crystal display cells, so it can be used in watches, calculators, calculators, etc. electronic typewriters, personal computers, car dart boards,
It can be used for liquid crystal displays such as portable televisions. Examples of uses other than liquid crystal displays include electrodes for photoconductive photoreceptors and surface heating elements. In addition, it has excellent light transmittance, heat resistance, surface hardness, etc., so it can be used for building windows, as well as filters and decorative boards for various display panels.

Next, examples of the present invention will be shown, and "parts" in the examples mean "parts by weight."

Note that the R value was measured using a Senarmont compensator (manufactured by Nippon Geikagaku Co., Ltd.) equipped with a polarizing microscope and using a sodium lamp as a light source. Visible light transmittance was measured using a Shimadzu Spectrophotometer (MPS-
5000) was used to measure from 400 mμ to 700 mμ.

Example 1 Phenoxy resin (Bakelite Phenoxy manufactured by Union Carbide) was added to dioxane (100 parts).
Regin (15 parts) and a reaction product of phenol and tolylene diisocyanate (9.0 parts) were added and dissolved by stirring at room temperature. This solution was cast onto a glass plate, left to stand in an atmosphere of 80℃ for 3 hours, and the thickness was approximately 100℃.
A uniform and transparent film of μ was obtained. This film was left under hot air at 90°C for 30 minutes, and then heat-treated in an atmosphere of 160°C under no tension for 15 minutes to obtain a transparent film (visible light transmittance: 93%). This film was cut out to a width of 10 mm and a length of 30 mm, and when both ends were pressed and bent, they contacted each other without breaking. The room temperature (25℃) and
The rigidity modulus (E′) at 120℃ is 3.12×
10 ¹⁰ dyne/cm ² , 1.07×10 ¹⁰ dyne/cm ² . This film was also insoluble in dioxane.
Even if this film is placed between a pair of polarizing films that are orthogonal to each other and rotated, neither the brightness nor the hue of the orthogonal polarizing films will change.
The R value was 5 mμ, and it was confirmed that it was non-optically active.

Example 2 Phenoxy resin (manufactured by Union Carbide, Bakelite Phenoxy) was added to a mixed solution of mekel ethyl ketone (50 parts) and Cellsolve Acetate (50 parts)
Resin: 40 copies), Coronate L [ Nippon Polyurethane Kogyo Co., Ltd., 70% solids, 50 parts of ethyl acetate solution] was added and dissolved by stirring at room temperature. This solution was cast onto a glass plate and allowed to stand for 2 hours in an atmosphere of 70°C to obtain a uniform transparent film with a thickness of 80 μm.
This film was heat-treated at 155°C for 20 minutes under no tension to obtain a film with a visible light transmittance of 93%. The rigidity (E') of this film at room temperature (25℃) and 110℃ is 3.85×10 ¹⁰ dyne/cm ² and 1.64×
It was 10 ¹⁰ dyne/ ^cm2 . Furthermore, this film was insoluble in organic solvents such as methyl ethyl ketone, cellosolve acetate, ethyl acetate, and cyclohexanone.

The R value was 3 mμ, and non-optical rotation was confirmed.

Example 3 Phenoxy resin (Union Carbide, Bakelite) was added to dimethyl formaldehyde (100 parts).
Phenoxy Resin (15 parts) and Coronate L (manufactured by Nippon Polyurethane Kogyo Co., Ltd.: 10 parts with a solid content of 70%) were added and dissolved by stirring at room temperature. This solution was cast onto a glass plate and allowed to stand for 4 hours in an atmosphere at 75°C to obtain a uniform, transparent film with a thickness of about 100 μm. As a result of evaluating this film in the same manner as in Example 1, the R value was
Non-optical rotation was confirmed at 15 mμ. This film was cut out to a width of 10 mm and a length of 30 mm, and was pressed and bent in the same manner as in Example 1, but did not break. Also width 5mm, length 20
Similar tests were carried out on pieces cut out to mm, but they did not break. The rigidity (E′) of this film is 2.01×10 ¹⁰ dyne/cm ² at room temperature, 120
At ℃ it was 4.74×10 ⁹ dyne/cm ² .

Example 4 Instead of the reaction product of phenol and tolylene diisocyanate used in Example 1, melamine formaldehyde resin (manufactured by American Cyanamid, Cynel 245 type: 10 parts) was added,
A uniform and transparent film with a thickness of about 70 μm was obtained in the same manner. This film was heat-treated under the same conditions as in Example 1 to obtain a transparent (transmittance: 91%) and uniform film. This film was cut into a size similar to that of Example 1 and its flexibility was evaluated, and it was found that it did not break and was good. Furthermore, this film was insoluble in organic solvents such as formaldehyde, cyclohexanone, and toluene. Furthermore, as a result of evaluating this film in the same manner as in Example 1, the R value was 8 mμ.
It was confirmed that it is non-optically active. The rigidity (E′) of this film is 3.59×10 ¹⁰ dyne/at room temperature.
cm ² and 9.56×10 ⁹ dyne/cm ² at 120°C.

Comparative Example 1 A polymethyl methacrylate film with a thickness of about 100 μ obtained by solvent casting was coated with a width of 10 μm in the same manner as in Example 1.
When I cut it out to a length of 30 mm and pressed both ends, it broke relatively easily and the center turned white.

Comparative Example 2 The films heat-treated under tension in one direction in Examples 1 and 4 had improved transparency, mechanical properties,
Although the chemical resistance was good, it showed optical rotation.

Claims (1)

[Claims] 1. General formula (In the formula, R ¹ to ^{R 6} are each hydrogen or carbon number 1 to 3
^R7 is a lower alkyl group having 2 to 4 carbon atoms, m is an integer of 0 to 3, and n is an integer of 20 to 300) A non-optically active film characterized in that it is formed from a phenoxy ether type crosslinked polymer obtained by crosslinking a hydrogen moiety with a polyfunctional compound.