JPH0459890A - Ferroelectric polymeric liquid crystal composition - Google Patents

Abstract

PURPOSE:To provide a novel composition composed of a ferroelectric polymeric liquid crystal compound and an optically inactive low-molecular liquid crystal compound having heterocyclic skeleton and developing smectic C phase, exhibiting quick response to the change of electric field near room temperature and having small temperature-dependency of the response. CONSTITUTION:The objective composition is composed of (A) 5-95mol% (preferably 10-80mol%) of a ferroelectric polymeric liquid crystal compound containing e.g. poly(meth)acrylate main chain, polychloroacrylate main chain, polyoxirane main chain, polysiloxane main chain, polyester main chain, etc., and having an average molecular weight of preferably 1,000-20,000 and (B) an optically inactive low-molecular liquid crystal compound having heterocyclic skeleton (e.g. pyrimidine, pyrazine, pyridazine, pyridine, dioxane or dioxaborinane skeleton) and exhibiting smectic C phase.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a novel ferroelectric polymer liquid crystal composition. More specifically, the present invention relates to the field of optoelectronics, particularly display elements, electro-optical shutters,
Ferroelectric polymer liquid crystal composition useful as various electro-optical elements such as electro-optical diaphragms, optical modulators, optical communication optical path switches, memories, liquid crystal printer heads, variable focal length lenses [Prior art] For liquid crystal optical elements The liquid crystal used is required to have properties such as film formability, alignment stability, and high-speed response to changes in electric field.

As a means of obtaining a polymer liquid crystal composition with excellent properties, it has been proposed to mix a low molecular weight liquid crystal compound with a polymer liquid crystal compound having an asymmetric carbon (Japanese Patent Application Laid-open No. 1983-1973).
-284291). Furthermore, it has been reported that a liquid crystal composition with excellent bistability can be obtained by using a low-molecular liquid crystal in which the direction of twist of the helical pitch is opposite to that of the high-molecular liquid crystal compound ( Unexamined Japanese Patent Publication 1986
-289090).

However, in order to prepare a liquid crystal composition by adding an optically active compound to an optically active compound, it is necessary to consider the sign of spontaneous polarization in addition to the direction of the helix during mixing, making the preparation complicated. be. In addition, the rotational viscosity of the composition tends to increase, and high-speed response to changes in electric field sufficient for practical use is not achieved.

[Problems to be Solved by the Invention 1] The present invention aims to provide a ferroelectric polymer liquid crystal composition that has excellent high-speed response to electric field changes near room temperature and has low temperature dependence of the high-speed response. It is something to do.

[Means to solve the problem]

The inventors of the present invention have conducted intensive research to solve the above-mentioned problems, and as a result, the object has been achieved with a composition consisting of a polymeric liquid crystal compound exhibiting ferroelectricity having a specific structure and a specific low-molecular liquid crystal compound. The present invention was completed based on this finding.

That is, the present invention provides a ferroelectric material comprising a polymeric liquid crystal compound having an asymmetric carbon and exhibiting ferroelectricity, and a non-optically active low-molecular liquid crystal compound having a heterocyclic skeleton and exhibiting a smectic C phase. The present invention provides a polymer liquid crystal composition.

The polymeric liquid crystal compound used in the present invention has asymmetric carbon and exhibits ferroelectricity.

In the liquid crystal composition of the present invention, since a non-optically active low-molecular liquid crystal compound is mixed with a high-molecular liquid crystal compound, the spontaneous polarization value of the entire composition is reduced. Therefore, it is preferable that the polymeric liquid crystal compound has a large spontaneous polarization of several tens to several hundreds of nC/d.

Moreover, as for the molecular weight of the polymeric liquid crystal compound, it is preferable that the average molecular weight (Mn) is 1.000 to 400.000. If the average molecular weight is less than 1,000, the film-forming properties of the resulting liquid crystal composition may deteriorate. If the average molecular weight exceeds 400,000, the response speed of the resulting liquid phase composition to changes in the electric field may become significantly slow. Furthermore, in order to obtain a liquid crystal composition that has both the film forming properties that depend on the composition being a polymer and the high-speed response to electric field changes that depend on the composition being a low molecule, more steps are required. The preferred average molecular weight is 1.000-20
,000.

Specific examples of such ferroelectric polymer liquid crystal compounds include the following.

1. Ferroelectric polymer liquid crystal with polyacrylate main chain (J, C. Dubois et al., Mo1. Cryst
, Liq, Cryst.

19B6. 137. 349) 4. Ferroelectric polymer liquid crystal having a polyoxirane main chain (described in JP-A No. 63-99204) 2. Ferroelectric polymer liquid crystal having a polymethacrylate main chain (described in JP-A-63-264629) Description) 5. Ferroelectric polymer liquid crystal having a polysiloxane main chain (J, C. Dubois et al., Mo1. Cryst
, Liq, Cryst.

19B6. 137. 349) 3. Ferroelectric polymer liquid crystal having a polychloroacrylate main chain (JP-A-63-280742)
3-280742) 6. Ferroelectric polymer liquid crystal CB having a polyester main chain.

(Described in JP-A-1-113424) (JP-A-1983-113424)
22918) (R. Zentel et al.
Liq, Crystal+ 198? + 2+ 83
) Furthermore, the low-molecular liquid crystal compound used in the present invention is a non-optically active compound that has a heterocyclic skeleton and exhibits a smectic C phase.

A low-molecular liquid crystal compound has a heterocyclic skeleton and has a smectic C
Therefore, the ferroelectric polymer liquid crystal composition obtained by preparing this low molecular liquid crystal compound and the above polymer liquid crystal compound has a chiral smectic C phase in a wide temperature range, and has rotational viscosity. is small and the response speed to electric field changes is large. Since this response speed has little temperature dependence, it has excellent high-speed response near room temperature.

In addition, since this low-molecular liquid crystal compound is non-optically active, there is no need to consider the direction of the mucomo helix when mixing it with the above-mentioned optically active high-molecular liquid crystal compound having an asymmetric carbon, and the composition Preparation of products becomes easier.

Examples of the heterocyclic skeleton present in this low-molecular liquid crystal compound include those of pyrimidine, pyrazine, pyridazine, pyridine, dioxane, dioxaborinane, and the like.

Specific examples of such low-molecular liquid crystal compounds include the following.

(1) Those having a pyrimidine skeleton (JP-A-1-168793) (Miiller, I., Ferroelectr
ics, ■Dish, 115.393) (Geelhaa
r, T, + Proceedings of the 15th LCD Symposium, Monthly,
46) (Dabrowski, R., Acta Unive
rsitatis Wratislaviensis,
1988 1084) (Dabroevski, R.
, l Acta [In1versitatisNra
tislaviensis, 1988 1084)
(2)! , "Having a radin skeleton (Dabrowski, R., 'Acta Univ.
ersitatis Wratislaviensis,
2ffi 1084) (Dabrowski, R.
, Acta LlniversitatjsWrati
slaviensis, 1988 1084) m=
6. n=1-7 m=9. n = 2 to 9 (Tadazumi Tokaibayashi et al., Proceedings of the 14th LCD Symposium, 38) (3) Those with a pyridazine skeleton (Dabrowski, R, ^cta Unive
rsitatis Glratislaviensis,
1988.1084) The ferroelectric polymer liquid crystal composition of the present invention is a parabolic composition consisting of the above-mentioned polymer liquid crystal compound and low-molecular liquid crystal compound, and the composition ratio thereof is as follows: It is preferable that the proportion in the whole product is in the range of 5 to 95 mol%. If it is less than 5 mol%,
The film forming properties of the composition may be significantly deteriorated, and if it exceeds 95 mol %, the response speed of the composition to changes in the electric field may be significantly slowed down.

In order to obtain a liquid crystal composition that has both the properties of film forming properties that depend on being a polymer and high-speed response to electric field changes that depend on being a low molecule, the entire composition of the above-mentioned polymer liquid crystal compound was used. It is more preferable that the proportion thereof is in the range of 10 to 80 mol%.

The ferroelectric polymer liquid crystal composition of the present invention may include, if necessary,
Other polymers may also be added, such as thermoplastic resins such as halogenated vinyl polymers, unsaturated alcohol or ether polymers, unsaturated carboxylic acid polymers, and crosslinkable resins such as epoxy resins and unsaturated polyesters. Furthermore, an epoxy adhesive, an acrylic adhesive, etc. may be added as an adhesive, and in addition, a plasticizer, a pigment, etc. may be added.

〔Example〕

Hereinafter, the present invention will be explained in detail based on Examples, but the present invention is not limited thereto.

Example 1 Using a polymer liquid crystal compound A having the following asymmetric carbon and exhibiting ferroelectricity, and a non-optically active low molecular liquid crystal compound B having the following heterocyclic skeleton and exhibiting a smectic C phase, A ferroelectric polymer liquid crystal composition containing 80 mol % of low molecular weight liquid crystal compound B was prepared by the following method.

Mn = 3000 (JP-A No. 63-264629 [) (JP-A No. 1-
168793) That is, 0.97 g (2 mmol) of high molecular weight liquid crystal compound A and 2.95 g (8 mmol) of low molecular weight liquid crystal compound B were dissolved in dichloromethane 20 to form a homogeneous solution. Next, the solvent was distilled off from this solution under reduced pressure, and the solution was further dried using a vacuum pump to completely remove the solvent, thereby obtaining the desired ferroelectric polymer liquid crystal composition.

The phase transition behavior of this ferroelectric polymer liquid crystal composition was determined by observation under a microscope and was as shown below.

(glass state, Sec”: chiral smectic C phase, SmA: smectic A phase, I
so: Tokichi phase) When the response time of this ferroelectric polymer liquid crystal composition to changes in electric field was measured, it was 800 μS at 25° C. (298 K) and 400 μs at 40° C. (313 K). Here, the response time to electric field changes was measured as follows.

That is, a ferroelectric polymer liquid crystal composition is sandwiched between two glass substrates with ITO, and a thickness of 2 μm is formed by the shearing method.
m orientation cells were prepared. Furthermore, ±2 under crossed nicols
An electric field of 0 MV/m was applied, and the time required for the amount of change in light transmittance to reach 0 to 90% was measured.

Comparative Example 1 Example 1 was prepared from 0.97 g (2 mmol) of a polymeric liquid crystal compound A having the following asymmetric carbon and exhibiting ferroelectricity and 3.06 g (8 mmol) of the following optically active low molecular weight liquid crystal compound C. The content of low molecular liquid crystal compound C was 80% by the same method as in 1.
A ferroelectric polymer liquid crystal composition of mol % was prepared.

Mn = 3000 (Japanese Patent Application Laid-Open No. 63-264629!
BP (manufactured by Teikoku Kagaku Co., Ltd. (trade name)) The phase transition behavior of this ferroelectric polymer liquid crystal composition was determined by observation under a microscope, and the results were as shown below.

A ferroelectric polymer liquid crystal composition containing 80 mol % of a low molecular weight liquid crystal compound was prepared.

Mn = 3000 (described in JP-A-63-264629) Furthermore, when the response time of this ferroelectric polymer liquid crystal composition to changes in electric field was measured in the same manner as in Example 1, it was found to be 25°C (29B
It was 2ms at K) and 300μs at 40”C (313K).

(Keller, p., Ferroelectri
cs+ 1984.58+3) The phase transition behavior of this ferroelectric polymer liquid crystal composition was determined by observation under a microscope and was as shown below.

Comparative Example 2 0.97 g (2 mmol) of a polymer liquid crystal compound A having the following asymmetric carbon and exhibiting ferroelectricity, and a non-optically active low molecular liquid crystal compound having the following phenylbenzoate skeleton and exhibiting a smectic C phase. From D3.64g (8 mmol),
The response time of this ferroelectric polymer liquid crystal composition to changes in electric field was measured in the same manner as in Example 1, and it was found to be 1.5 m at 25°C (298K).
s, 500.s at 40°C (313K). ! /S.

FIG. 1 shows the temperature dependence of the response time to electric field changes of the ferroelectric polymer liquid crystal compositions and polymer liquid crystal compound A obtained in Example 1, Comparative Example 1, and Comparative Example 2. The horizontal axis is The temperature (K) and the vertical axis are response time (seconds).

From this graph, we learned the following.

The ferroelectric polymer liquid crystal compositions obtained in Example 1, Comparative Example 1, and Comparative Example 2 all have a faster response to electric field changes than Polymer Liquid Crystal Compound A alone, but they are not optically active. Compared to the composition of Comparative Example 1, which added a low-molecular-weight liquid crystal compound, the composition of Example 1 and the composition of Comparative Example 2, which added a non-optically active low-molecular-weight liquid crystal compound, showed a higher temperature dependence of response speed. The response speed is faster, especially near room temperature.

Furthermore, the composition of Example 1 in which a non-optically active low-molecular liquid crystal compound with a heterocyclic skeleton was added was better than the composition of Comparative Example 2 in which a non-optically active low-molecular liquid crystal compound with a phenylbenzoate skeleton was added. Excellent high-speed response to changes in electric field.

In other words, by adding a non-optically active low-molecular liquid crystal compound to an optically active high-molecular liquid crystal compound containing an asymmetric carbon, the temperature dependence of the response speed to electric field changes is reduced, and the response speed near room temperature is reduced. It is possible to achieve faster speeds. The effect is greater for low-molecular liquid crystal compounds having a heterocyclic skeleton than for low-molecular liquid crystal compounds having no heterocyclic skeleton.

Example 2 Example 2 was prepared from 3.69 g (7 mmol) of a polymeric liquid crystal compound E having the following asymmetric carbon and exhibiting ferroelectricity and 1.38 g (3 mmol) of the following optically active low molecular weight liquid crystal compound F. The content of low molecular liquid crystal compound F was 30% by the same method as in 1.
A ferroelectric polymer liquid crystal composition of mol % was prepared.

E: cn.

Mn = 9000 (Referenced in Japanese Patent Application Laid-Open No. 63-280742! Table 1 (Reported in Proceedings of the 15th Liquid Crystal Symposium, 1989.46) 20 Phase transition behavior of ferroelectric polymer liquid crystal compositions As determined by observation under a microscope, the results were as shown below.

Furthermore, when the response time of this ferroelectric polymer liquid crystal composition to changes in electric field was measured in the same manner as in Example 1, the results shown in Table 1 were obtained. For comparison, Table 1 also lists the response time of the polymeric liquid crystal compound E alone to changes in the electric field.

By adding low-molecular liquid crystal compound F to the high-molecular liquid crystal compound, a ferroelectric polymer liquid crystal composition in which the response speed to electric field changes has small temperature dependence was obtained.

Example 3 A liquid crystal optical element was manufactured using the ferroelectric polymer liquid crystal composition prepared in Example 1 as the liquid crystal material, using two flexible continuous substrates with transparent electrodes as substrate materials. The manufacturing equipment used for the fabrication is schematically shown in FIG.

The manufacturing apparatus shown in FIG. 2 includes a coating step A in which a melt or solution of a ferroelectric polymer liquid crystal composition is applied onto one continuous substrate, and a liquid crystal layer made of a ferroelectric polymer liquid crystal composition is applied. The process consists of a laminating process B in which the continuous substrate and the counter substrate are laminated together, and an alignment process C in which the ferroelectric polymer liquid crystal composition sandwiched in the obtained laminate is aligned. The production line is operated at a constant speed V.

At the same time as the flexible substrate 25 with transparent electrodes is fed out from the substrate feeding roll 1, the substrate protection films 21 and 22 pasted on both sides of the substrate 25 are wound up by the protective film winding rolls 2 and 3, respectively, and the substrate 2
Stripped from 5.

The substrate 25 from which the protective film has been removed is sent to the coating process A via the auxiliary roll 4.

The coating device used in the coating process A includes a metering discharger 7 that quantitatively discharges the melt or solution of the ferroelectric polymer liquid crystal composition, an impregnation coating head 5 equipped with an impregnation material at the tip, and a metering discharger. It consists of a silicone rubber tube 6 which conveys the melt or solution of the ferroelectric polymer liquid crystal composition discharged from 7 to the bottom 5 of the impregnation coating spatula. The impregnating coating head 5 makes a constant periodic motion using the end of the silicone rubber tube 6 as a fixed point so that the impregnating material intermittently contacts the surface of the transparent electrode layer of the substrate 25. While the impregnating material is in contact with the transparent electrode layer of the substrate 25, the metering dispenser 7 quantitatively dispenses the melt or solution of the ferroelectric polymer liquid crystal composition in conjunction with the movement of the impregnation coating head 5. The discharged melt or solution of the ferroelectric polymer liquid crystal composition is sent through the silicone rubber tube 6 to the impregnating material of the impregnating coating head 5 that is in contact with the substrate 25, and is maintained at a constant line speed V. Board 5 moving with
The transparent electrode layer is coated on the transparent electrode layer.

The substrate 25 coated with the melt or solution of the ferroelectric polymer liquid crystal composition is sent to the lamination step B via auxiliary rolls 8 and 9. When a solution of a ferroelectric polymer liquid crystal composition is applied, the applied layer is dried in a hot air dryer 28 provided between auxiliary rolls 8 and 9, and the solvent used for preparing the solution is removed. Remove.

The substrate 25 coated with the ferroelectric polymer liquid crystal layer is sent to the lamination process B, and the opposing flexible substrate 26 with transparent electrodes is fed out from the opposing substrate feeding roll 18 and protected in the same way as the substrate 25. The substrate protection films 23 and 24 are removed by the film take-up rolls 19 and 20.
After being removed, it is fed at the same line speed V as the substrate 25. Next, the substrate 25 and the counter substrate 26 sent to the lamination step B are passed between a pair of laminating rolls 10 and 11, so that the ferroelectric polymer liquid crystal composition coated on the transparent electrode of the substrate 25 is bonded to the substrate. 25 and the transparent electrodes on the counter substrate 26. The laminating rolls 10 and 11 are heated (the surface temperature of the laminating roll is
).

The obtained laminate is sent to orientation treatment step C via auxiliary rolls 12 and 29.

In the alignment treatment step C, the laminate is first heated through a heating furnace 13 equipped with an infrared heater and a blower to a temperature at which the liquid crystal exhibits a togoyoshi phase or a mixture of a togoyoshi phase and a liquid crystal phase (heating furnace temperature 2T2). After that, the ferroelectric polymer liquid crystal composition in the laminate is brought into bending deformation and oriented by moving it in close contact with the roll surfaces of the alignment cooling rolls 14 and 15 one after another. In this alignment process, in order to orient the liquid crystal by shearing while cooling, the surface temperatures of the alignment cooling rolls 14 and 15 are set to a temperature at which the liquid crystal exhibits a liquid crystal phase such as a smectic A phase or a chiral smectic C phase, respectively. (Surface temperature of the orientation cooling roll 14 T3,
The surface temperature of the orientation cooling roll 15 is adjusted to T4).

The liquid crystal optical element 27 obtained by the alignment treatment of the laminate passes through the auxiliary roll 16 and is wound up on the winding roll 170.
can then be cut to an appropriate size.

In this manner, by manufacturing a liquid crystal optical element using a continuous substrate and the manufacturing apparatus shown in FIG. 2, coating, lamination, and alignment treatments of a polymeric liquid crystal composition can be performed continuously.

In this example, ITo is used as a flexible continuous substrate!
PE5 (polyether sulfone) substrate (thickness: 110
0tI, width 2BCI+) (FST-1351, manufactured by Juju Bakelite ■, trade name), a liquid crystal optical element was manufactured under the following conditions.

Line speed: v = 2.2 m/min Temperature inside hot air dryer: Ts = 40°C Surface temperature of laminating roll 10.11: T, = 40°C Temperature inside heating furnace 13: 'r, = 85°C Cooling for orientation Surface temperature of roll 14: Tx = 16°C Surface temperature of orientation cooling roll 15: T, = 70°C Auxiliary roll 4
．． 8.9.12. As 16 and 29, iron pipes (diameter 40 cm, width 300 cm) with chrome plated surfaces were used.

As the laminating roll 10, a rubber roll (φ80
300 width) as laminating roll 11,
Iron pipe with chrome plated surface (φ80m, diameter 300m)
was used. As the cooling rolls 14 and 15 for orientation, iron tubes (φ80 mm, width 3
00kaku) was used.

Using a 10% by weight solution of the ferroelectric polymer liquid crystal composition prepared in Example 1 in dichloromethane, 2.7 cc was sent from the metering dispenser 7 to the impregnation coating head 5 for each coating. The spatula 5 for impregnating coating uses Bertalin (trade name) manufactured by Kanebo Corporation cut into a width of 25 CIl as an impregnating material, and for each coating, a length of about 40 cm is applied onto the transparent electrode layer of the substrate 25. Then, a solution of the above ferroelectric polymer liquid crystal composition was applied. Next, a lamination step and an alignment treatment step were carried out under the above conditions, and the obtained liquid crystal optical element was wound up with a winding roll 17.
25cm x 40cm from the roll-shaped liquid crystal optical element.
A ci+ liquid crystal optical element was cut out. The film thickness of the liquid crystal portion of the cut out liquid crystal optical element was approximately 2.5 μm. The contrast of this liquid crystal optical element was measured under crossed nicol conditions, and a good value of 50 was obtained with an application of ±5 cm. In addition, no contrast unevenness or color unevenness due to uneven thickness of the liquid crystal part was observed throughout the device.
It was confirmed that a good oriented film was obtained.

〔Effect of the invention〕

The ferroelectric polymer liquid crystal composition obtained by the present invention has excellent high-speed response to changes in electric field near room temperature, has small temperature dependence of the high-speed response, and has excellent film formability. Therefore, it has extremely great industrial value.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the temperature dependence of the response time to electric field changes of the ferroelectric polymer liquid crystal compositions obtained in Example 1, Comparative Example 1, and Comparative Example 2, and polymer liquid crystal compound A alone. The horizontal axis is temperature (K), and the vertical axis is response time (seconds). FIG. 2 is a schematic diagram showing a manufacturing apparatus for a liquid crystal optical element used in Examples. Explanation of symbols All cloth process B: Lamination process, □C: Substrate edge roll in orientation treatment process 2.3.19.20: Protective film winding roll 4.8.9.12.16.29: Auxiliary roll 5: Impregnation coating head 6: Silicone rubber tube 7: Meter dispenser 10.11
: Laminating roll 13: Heating furnace equipped with an infrared heater and blower 14.15
; Orientation cooling roll 17: Winding roll 18 Two opposing substrate feeding rolls 21, 22, 23, 24: Substrate protective film 25, 26
: Flexible continuous substrate with transparent electrode 27 : Liquid crystal optical element (before cutting) 28 : Warm air dryer V Ni line speed TI : Surface temperature T2 of laminating roll 10.11 : Heating furnace 13
Temperature T inside: Surface temperature T4 of cooling roll for orientation 14 : Surface temperature Ts of cooling roll 15 for orientation: Temperature inside hot air dryer 28

Claims (1)

[Claims] 1. A ferroelectric polymer characterized by consisting of a polymer liquid crystal compound having an asymmetric carbon and exhibiting ferroelectricity, and a non-optically active low molecular liquid crystal compound having a heterocyclic skeleton and exhibiting a smectic C phase. liquid crystal composition.