JPH01113727A - High-polymer liquid crystal substrate - Google Patents

Abstract

PURPOSE:To decrease defects such as impurities and pinholes and to form a thin liquid crystal film having a uniform thickness by sticking the monomer component of a high-polymer liquid crystal onto a substrate and polymerizing the same, thereby forming the thin film on the substrate. CONSTITUTION:Glass, metals, plastic, etc., are used as the substrate 1 to be used and the substrate having grooves 2 of about 0.05-0.2mum depth on the surface is used as well. The monomer component of the high-polymer liquid crystal is stuck onto this substrate 1 by evaporation or sublimation. This substrate 1 is heated or is subjected to heating reaction by plasma, UV rays, electron beams, etc., to polymerize the monomer component. The thin film of the high-polymer liquid crystal which has the high adhesiveness between the high- polymer liquid crystal layer and the substrate 1, eliminates the impurities and pinhole defects and has a uniform film thickness is thereby formed easily on various kinds of the substrates.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a polymer liquid crystal substrate having means for directly forming a polymer liquid crystal thin film on the substrate from monomer components, comprising:
This invention relates to a polymer liquid crystal substrate that is homogeneous, has excellent orientation, and has excellent mechanical strength.

[Conventional technology] Conventionally, polymer liquid crystals, especially side-chain type polymer liquid crystals.

The side chains have a rigid molecular structure, and the main chain of main chain polymer liquid crystals generally consists of mesogen groups and flexible chains via ester bonds, and both undergo a phase transition with temperature, for example, from solid to nematic. Phenomena such as phase → isotropic fluid phase or solid → smectic phase → nematic phase → isotropic fluid phase are observed.

On the other hand, polymer liquid crystals have the following characteristics from the aspect of polymers:
Functionalization such as thin films and larger areas can be easily achieved, and improvements in physical properties such as physical and chemical stability and durability can be expected.

Conventionally, the rubbing method (F, Kahn: Phys.
, Today, 66 (1982)), oblique evaporation method (J.

Janning: Appl, Phys, L
ett,, 21. 173 (1972)), grating method (M, Nakamura and M,
Ura: J, Appl, Phys,, 52
．． 210 (1981)) and the shearing method using mechanical force. In addition, it has also been reported that liquid crystal molecules can be oriented in an electric or magnetic field.

However, among the conventional methods mentioned above, alignment methods that mainly use surface energy, such as rubbing, oblique evaporation, and grating, are effective for low-molecular liquid crystals, but cannot achieve good alignment for polymer liquid crystals. It was difficult. Furthermore, the alignment method using a magnetic field or electric field is difficult to process uniformly over a large area, and requires a considerable amount of time for alignment treatment, which is not practical. In the shearing method, the thickness is limited, and it is difficult to achieve a practical thickness with polymer liquid crystals.

Usually, polymer liquid crystals are synthesized by dissolving the 100% polymer component in an organic solvent, performing a heating reaction in the presence of a reaction initiator or catalyst, and after the reaction is completed, impurities and low molecular weight particles are removed by reprecipitation. The target object is obtained by removing the body, etc. Methods for coating the polymer liquid crystal obtained in this way on a substrate include casting, dipping, and spin coating using a spinner. Usually, the polymer liquid crystal is dissolved in an appropriate organic solvent. The viscosity is lowered and used for coating.

However, during the synthesis operation of the polymer liquid crystal described above, a large amount of solvent is required as a reaction solvent and a reprecipitation solvent, and the operation process is performed in several steps. Further problems in the coating operation include the need for purification to remove the adverse effects of impurities in the solvent used, and the possibility that defects such as pinholes may occur in the thin film during solvent evaporation. Therefore, there is currently a demand for a better method for forming thin films.

[Problems to be Solved by the Invention] The present invention solves the above-mentioned process problems and provides a polymer liquid crystal that can be easily and precisely formed into a thin film on a predetermined substrate. The aim is to provide a liquid crystal substrate.

[Means for Solving the Problems] That is, the present invention includes means for depositing a heptamer component of a polymeric liquid crystal on a substrate and then polymerizing it to form a polymeric liquid crystal thin film on the substrate. This is a characteristic polymer liquid crystal substrate.

The present invention will be explained in detail below.

In the present invention, the monomer components of the polymer liquid crystal are evaporated and
After being deposited on a given substrate by condensation or sublimation,
A polymer liquid crystal thin film can be formed on the substrate by polymerization using energy such as heating, plasma, ultraviolet rays, or electron beams.

The above-mentioned monomer component used in the present invention is not particularly limited, and a wide range of polymer/liquid crystal monomers can be used.

For example, a main chain polymer liquid crystal exhibiting thermotropic liquid crystal properties can be used. Specific compounds that can be used as mesogenic groups include terphenyldicarboxylic acid, p-
Terephthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, stilbenzenedicarboxylic acid, azobenzenedicarboxylic acid, azoxybenzenedicarboxylic acid, cyclohexanedicarboxylic acid, biphenyletherdicarboxylic acid.

Dicarboxylic acids such as biphenylethanedicarboxylic acid, biphenylethanedicarboxylic acid or carboxycinnamic acid, hydroquinone, dihydroxybiphenyl, dihydroxyterphenyl, dihydroxyazobenzene,
Diols such as dihydroxyazoxybenzene, dihydroxydimethylazobenzene, dihydroxydimethylazoxybenzene, dihydroxypyridazine, dihydroxynaphthalene, dihydroxyphenyl ether, or bis(hydroxyphenoxy)ethane, or hydroxybenzoic acid, hydroxybiphenylcarboxylic acid, Hydroxycarboxylic acids such as pytroxyterphenylcarboxylic acid, hydroxycinnamic acid, hydroxyazobenzenecarboxylic acid, hydroxyazoxybenzenecarboxylic acid or hydroxystilbenecarboxylic acid can be used.

As the flexible chain, a group represented by the following formula [I] is used.

One←÷be! 12) 7-+0→;←)--[I] (in the formula,
2 is an integer from 1 to 4, m is 0 or l, n is 1 to 15
(Integers up to Diols, diols such as dodecanediol, tridecanediol, tetradecanediol, pentadecanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, nonaethylene glycol, or tridecaethylene glycol, or malonic acid, succinic acid, glutaric acid, adipic acid Dicarboxylic acids such as , pimelic acid, speric acid, azelaic acid, or sebacic acid can be used.

Furthermore, as an optically active group, a difunctional one can be used as a raw material for a flexible chain. Specifically, (+)-3-methyl-1,6-hexanediol (-)
-3-methyl-1,6-hexanediol (+)-3-
Methylazipic acid (-)-3-methyladipic acid (D)-mannitol
) (L)-mannitol (L-mannitol) (liepantothenic acid (+)-1,2-4-trihydroxy-3,3-dimethylbutane (-)-1,2-propanediol (÷)-1, 2-Propanediol (+)-lactic acid (-)-lactic acid (23,5S)-2-methyl-3-oxahexane-1
, 5-diol (2S, 5S, 8S)-2,5-dimethyl-3,6-thioxanonan-1,8-diol, etc. can be used.

Among the above carboxylic acid components, thionyl chloride or the like is converted into an acid chloride and used in the following polymerization step.

Typical polymer liquid crystals include, but are not limited to, those listed below.

(The book represents an optically active group.) (x + y = 1, X≧o, i. Also, 15>n≧1) In addition, the polymer liquid crystal after polymerization has thermotropic liquid crystallinity. Also preferred are acrylic esters and methacrylic esters.

These esters generally have a liquid crystalline core portion (mesogen portion) through hydrocarbon bends, and the esters may be represented by, for example, the following general formula (%).They are not limited to these.

General formula [11] General formula [ml R8 R,:H,CH3 p: 12 integer to l x: +, -o-, -coo- Y・-0-0-, 豫)℃t.

-o-cH-N-(Qto, +x-co-@to.

4 defense N-N (pregnancy, ÷ coo number.

(shico(to, (to cu=cu-coo(to).

(Another coozu H place-◎ is 4coo-@-.

豫) stone needle oco+, () (sawa ocu, (C house).

4coO+C匡■(t.

■ Z Knee (H=CI(-COO-Rz, -COO-R2
, -0-Rt, -C-Rt.

-0CO-R2, -NH-R2, -NR2, -(:N,
-H.

C1-2o alkyl group, C1-2o asymmetric carbon-containing alkyl group, -F, -CR, -Br, -NH,, -
NO2n2: c, ~2o alkyl group, 61~2o asymmetric carbon-containing alkyl group In order to attach the above monomer onto the substrate, a vacuum degree of 10-
This is achieved by leaving the monomer component and the substrate at rest with an appropriate distance between them under a vacuum of about 2 to 10 Torr, and further heating the monomer if necessary.

After stacking the layers on the substrate in this manner, the substrate is heated under the vacuum, or taken out and placed under atmospheric pressure, preferably in an inert atmosphere such as nitrogen or argon, or exposed to plasma. - By irradiating active energy rays such as ultraviolet rays and electron beams, polymerization progresses and a thin film of polymer liquid crystal can be formed.

By processing an alignment film on the substrate in advance, the alignment of the polymer liquid crystal thin film can be controlled. Methods for performing alignment treatment on the substrate include a rubbing method, an oblique evaporation method, and a method of applying a magnetic field.

Substrates used in the present invention include glass, metal, plastic, etc., but also substrates having a conductive layer such as an ITO film, and as shown in FIGS. 1(a) to (d),
It is also applicable to a substrate 1 having grooves 2 on the surface with a depth of approximately 0.05 to 0.2 p and ta.

[Function] The polymeric liquid crystal substrate of the present invention has excellent adhesion between the substrate and the polymeric liquid crystal layer, since the hexamer component of the polymeric liquid crystal is adhered onto the substrate by evaporation or sublimation. A thin film of high-precision monomer components is uniformly laminated on the material, and polymerization is carried out by heating the thin film or applying active energy such as plasma, ultraviolet rays, or electron beams.
A polymer liquid crystal thin film with a uniform thickness can be formed without contamination of impurities or generation of pinholes.

[Example] Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 A glass substrate with a thickness of 1 - 9 (height: 50 mm) and a width of 50 mm (width) square was used as a seven-pointed glass substrate using a compound represented by the following formula [IV]. ] A Petri dish containing a mixture of 0.2% by weight of the compound;
They were left standing in a vacuum container with an interval of Oc■. The inside of this vacuum container was evacuated to a degree of vacuum of 5 x 10-'Torr, and the petri dish containing the compound of the above formula [IV] was heated to 50°C and maintained for 30 minutes, after which nitrogen gas was introduced into the system. The pressure was returned to atmospheric pressure, and the glass substrate with the monomer layer attached was taken out.

Next, the glass substrate was irradiated with ultraviolet rays for about 1 hour from a distance of 15 cs using a 500 W water-cooled ultra-high pressure mercury lamp in a nitrogen atmosphere. After irradiation, the film thickness was measured and found to be 3.2 pm. The obtained polymer thin film exhibited a liquid crystal phase (nematic) at 97°C to 120°C.

When the surface of the thin film was observed using an optical microscope under 50 times magnification, no defects such as pinholes were observed.

The above polymer liquid crystal substrate
After conducting a heat cycle test under the temperature conditions of 1O, an adhesion test between the polymer thin film layer and the glass substrate was performed, and the substrate peeling test was 65/10G (65 out of 100 squares adhered). Met.

Example 2 A glass substrate with a seven-layer layer attached was obtained in the same manner as in Example 1, except that the seven-layer compound was changed to a compound [V] represented by the following formula [V]. Next, the glass substrate was irradiated with an electron beam at an acceleration voltage of 150 kV in a nitrogen atmosphere.

The thickness of the obtained polymer layer was 2.61 Ls. This polymer thin film exhibited a liquid crystal phase (smectic) at 67.0 to 180°C. Similar to Example 1, no defects were observed by optical microscopic observation.

Example 3 A polyamic acid solution (manufactured by Hitachi Chemical Co., Ltd., trade name PIQ: non-volatile content concentration 3wt) was applied to the same glass substrate as in Example 1.
A substrate having a polymeric liquid crystal thin film was prepared in the same manner as in Example 1, except that a substrate having a polyimide alignment film coated with %) and uniaxially aligned by a rubbing method after heating was used. A glass substrate of the same shape was placed on top of this liquid crystal layer with a spacer having a thickness of 2.8 μm interposed therebetween. The above recording medium was heated to 140° C. to bring the liquid crystal layer into an isotropic state. When gradually cooled at a speed of 2℃/sin,
The liquid crystal layer was uniaxially aligned.

Example 4 It has a groove with the cross-sectional shape shown in FIG. A polymer liquid crystal thin film was formed on the substrate in the same manner as in Example 2, except that a glass substrate of 50mm square and 111mm thick was used.

On top of this liquid crystal layer, a thickness of 2. :l A glass substrate of the same shape was mounted on a mold frame via a #Lm spacer. The above recording medium is heated to 200° C. to bring the liquid crystal layer into an isotropic state. When the liquid crystal layer was gradually cooled at 2° C./in, the liquid crystal layer was completely oriented along the above-mentioned grooves.

Comparative Example 1 Monomer 10 of formula [IV] similar to that used in Example 1
g was treated with 50% of dehydrated benzene as a solvent and azobisisobutyronitrile as a polymerization initiator.
7% by weight under nitrogen atmosphere.
Solution polymerization was performed by heating at 0° C. for 30 hours. After the reaction,
The reaction solution was poured into methanol, and the precipitated solid was filtered out. The dried solid was dissolved in chloroform, methanol was used as a precipitation solvent, and this reprecipitation operation was performed twice. The polymer was then dried and used as follows.

The above polymer was dissolved in methylene chloride at a concentration of 10 wt%, and the thickness was 1 x 50 x 50 using a spinner.
Coated on a corner glass substrate. Special grade methylene chloride was purified by distillation, and the solution was filtered through a 0.21 Lm filter before being applied.

After coating and drying in a hot air dryer at 40°C, the film thickness was measured and found to be 2.8 u, tm at the center of rotation of the spinner.
It was 2.1 p-ra at 15 mm outside.

Furthermore, when the surface of the thin film was observed with an optical microscope under 50 times magnification, pinholes were observed in the field of view in some places. This polymer liquid crystal substrate was subjected to a heat cycle test under the same conditions as in Example 1, and then an adhesion test was conducted.
/100, which was lower than in Example 1.

Example 5 Adding N to an ethanol solution of 0.1 mol of hydroxybenzoic acid
Add 12 moles of aOHO, then 0 benzyl chloride
．． 12 moles were added. The solvent was distilled off and the residue was recrystallized to obtain benzyl-hydroxybenzoic acid. Bis(4-benzyloxycarbonylphenyl) terephthalate was obtained by reacting 0.2 mol of this benzyl-hydroxybenzoic acid with 0.1 mol of terephthalic acid chloride in pyridine. This diester purified by recrystallization is heated in trifluoroacetic acid to obtain bis(
4-carboxyphenyl) terephthalate was obtained. This was reacted with thionyl chloride to obtain acid chloride (■).

A polyamic acid solution (manufactured by Hitachi Chemical Co., Ltd., PIQ: non-volatile content concentration 3 wt%) was applied to a glass substrate measuring 50 cm vertically and 50 cm horizontally, and after heating, a polyimide was subjected to a uniaxial alignment treatment using a rubbing method. The substrate on which the alignment film has been formed is
and 1,9-nonanediol were placed in a vacuum container at a distance of 10 cm from two petri dishes containing 1,9-nonanediol and 1,9-nonanediol. The inside of this vacuum container was evacuated to a vacuum level of 5 x 10'' Torr, and the above petri dish was heated to 40°C and held for 30 minutes, then nitrogen gas was introduced into the system to return it to atmospheric pressure. Ta.

Next, the glass substrate to which the raw material components have been attached is irradiated with far infrared rays in a nitrogen atmosphere, and the substrate is heated at approximately 130°C for 6 hours.
The mixture was heated for a period of time to allow polymerization to proceed. After heating, the film thickness was measured and found to be 2ILIl. The obtained polymer thin film was 9
It exhibited a liquid crystal phase (smectic) at 0°C to 230''C.

Furthermore, when the surface of the thin film was observed using an optical microscope under 50 times magnification, no defects such as pinholes were observed.

This polymer liquid crystal thin film was partially oriented as it was. A glass substrate was placed on top of this liquid crystal layer with a 1.8-thick spacer interposed therebetween. 2 of the above recording media
After heating to 50°C to make the liquid crystal layer isotropic, 2
When slowly cooled at .degree. C./inch, the liquid crystal layer was uniaxially and uniformly aligned.

The above polymer liquid crystal substrate is heated at 30°C x 2H → 60°C x 2.
After 10 cycles of a heat cycle test under the temperature condition of H, an adhesion test between the polymer thin film layer and the glass substrate was performed, and the result was 70/100 in the substrate peel test.

Example 6 Acid chloride ■ was obtained by reacting 4.4″-terphenyldicarboxylic acid with thionyl chloride. It had a groove with the cross-sectional shape shown in FIG. 1(a), and the depth of the groove was as follows: oaIL Shoes, groove width 10 holes IL11, groove spacing 0.6 mm length 5
A glass substrate measuring 0 cm, 50 mm wide and 1 mm thick was placed in a vacuum container at a distance of 10 cm from two Petri dishes containing the above-mentioned ■ and tetraethylene glycol, respectively. The subsequent operations were performed in the same manner as in Example 5, and a polymer liquid crystal thin film was formed on a glass substrate. The film thickness was 1.81 L-. This polymer liquid crystal exhibited a liquid crystal phase (smectic) at 125°C to 250°C. As in Example 5, no defects were observed in the optical microscope observation of the thin film surface. This polymer liquid crystal thin film was partially oriented as it was. A glass substrate was placed on top of this liquid crystal layer with a spacer having a thickness of 1.61 L being interposed therebetween. When the recording medium was heated to 270° C. to be in an isotropic state and then gradually cooled at 2° C./win, the liquid crystal layer was completely oriented along the grooves.

Comparative Example 2 The acid chloride obtained in Example 5 and 1,9-nonanediol were heated in dichloroethane at 70°C x 1 under a nitrogen atmosphere.
After reacting for 5 hours, the solvent was distilled off, washed with methanol, and dried. The resulting main chain polymer liquid crystal was provided as follows.

The above polymer was dissolved in chloroform at a concentration of 5 wt %, and applied using a spinner onto a 1 mm thick, 50 x 50 square glass substrate. Chloroform is purified by distillation of special grade, and the solution is filtered through a 0.21Lm filter.
Used for coating. After coating and drying in a dryer at 40°C, the film thickness was measured and found to be 21 Lm at the center of rotation of the spinner.
It was 1.7 JL■ at 8mm outside.

Furthermore, when the surface of the thin film was observed with an optical microscope under 50 times magnification, pinholes were observed in the field of view in some places.

Comparative Example 3 Using the same main chain type polymer liquid crystal as used in Comparative Example 2,
By a similar method, a polymer liquid crystal thin film was formed on a glass substrate on which a polyimide alignment film was formed in the same manner as in Example 5. The film thickness is 27L11. 1.5 at the outer periphery
It was gta. On top of this liquid crystal layer, a thickness t, s IL
The glass substrates were stacked with - spacers interposed therebetween. After heating the above recording medium to 250°C to make it into the equi-lucky phase, 2
When it was slowly cooled at °C/win, the orientation was insufficient and uniform uniaxial orientation could not be obtained.

This polymer liquid crystal substrate was subjected to a heat cycle test under the same conditions as in Example 5, and then an adhesion test was conducted, and the result was 8/1.
00, which was lower than in Example 5.

[Effects of the Invention] As explained above, according to the polymer liquid crystal substrate of the present invention, a polymer liquid crystal thin film with few defects and impurities and a constant film thickness can be easily formed on various substrates. Ru.

Further, since the polymer liquid crystal produced according to the present invention has excellent adhesion to the substrate, it is possible to provide a polymer liquid crystal substrate with excellent environmental resistance.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of the groove shape of a substrate used in the present invention.

Claims (2)

[Claims] (1) A polymer liquid crystal substrate characterized by having means for depositing a polymer liquid crystal monomer component on the substrate and then polymerizing it to form a polymer liquid crystal thin film on the substrate. (2) The polymer liquid crystal substrate according to claim 1, wherein polymerization is carried out by heating, plasma, ultraviolet rays, or electron beam energy.