Some standard content:
Military Standard of the Electronic Industry of the People's Republic of China FL5971
SJ20638-97
Specification for liquid crystal materials for TFT-LCD
Speceification for liquid crystal materials for TFT-LCD1997-06-17 Issued
1997-10-01 Implementation
Approved by the Ministry of Electronics Industry of the People's Republic of China Military Standard of the Electronic Industry of the People's Republic of China Specification for liquid crystal materials for TFT-LCD
Specificatian for liquid crystal materials for TFT-LCD1 Scope
SJ20638-97
1.1 Subject Content
This specification specifies the requirements, quality assurance provisions, delivery preparation and related provisions for liquid crystal materials for TFT-LCD. 1.2 Scope of Application
This specification applies to liquid crystal materials for TFT-LCD (hereinafter referred to as liquid crystal materials). 2 Referenced Documents
There are no provisions in this chapter.
3 Requirements
3.1 QualificationWww.bzxZ.net
Products submitted in accordance with this specification shall be qualified products or approved products. 3.2 Trial products
When specified in the contract, the contractor shall provide trial samples. Unless otherwise specified, the trial samples shall meet all the requirements of this specification.
3.3 State
At room temperature, the liquid crystal material is a liquid.
3.4 Color
The liquid crystal material is milky white.
3.5 Melting point
The melting point of the liquid crystal material shall be lower than -40°C. 3.6 Clearing point
The clearing point of the liquid crystal material shall be higher than 85°C.
3.7 Viscosity
The viscosity of the liquid crystal material shall be less than 25mm2/s (2 billion). 3.8 Resistivity ()
The resistivity of the liquid crystal material shall be greater than 1×1012n-cm. 3.9 Optical anisotropy (2nm)
The optical anisotropy of the liquid crystal material is 0.06~0.12. Ministry of Electronics Industry of the People's Republic of China issued on June 17, 1997 and implemented on October 1, 1997
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3.10 Extraordinary light refractive index (n)
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The non-band-seeking light refractive index of the liquid crystal material is 1.5~1.7. 3.11 Dielectric anisotropy (4e)
The dielectric anisotropy of the liquid crystal material is 5~10. 3. 12 Dielectric constant (e)
The dielectric constant of the liquid crystal material when the liquid crystal director is parallel to the electric field is 7~13. 3.13 Threshold voltage (V10,0.20)
The threshold voltage of the axillar material is not more than 2.5V. 3.14 Saturation voltage (Vg0.0.20)
The saturation voltage of the liquid crystal material is less than 4V.
4 Quality Assurance Provisions
4.1 Inspection Responsibility
Unless otherwise specified in the contract or order, the contractor shall be responsible for completing all inspections specified in this specification. If necessary, the ordering party or the superior appraisal agency has the right to inspect any inspection item described in the specification. 4.1.1 Qualification Responsibility
All products must meet all requirements of Chapter 3 and Chapter 5 of this specification. The inspections specified in this specification shall become an integral part of the contractor's entire inspection system or quality plan. If the contract includes inspection requirements not specified in this specification, the contractor shall also ensure that the products submitted for acceptance meet the contract requirements. Quality consistency sampling does not allow the submission of products that are known to be defective, nor can the ordering party be required to accept defective products. 4.2 Inspection Classification
The inspections specified in this specification are divided into:
. Appraisal inspection;
h. Quality-Conformity Inspection.
4.3 Standard atmospheric conditions for testing
Unless otherwise specified, various tests shall be carried out under the following environmental conditions: Ambient temperature: 15~35C;
Relative humidity: 45%~75%;
Atmospheric pressure: 86~106kPac
4.4 Identification test
Identification test is carried out before product submission. When there are major changes in raw materials or manufacturing processes that may affect the identification results, identification test should also be carried out.
4.4.1 Inspection location
Unless otherwise specified, the location of trial production inspection is a laboratory or testing center approved by the relevant competent authorities. 4.4.2 Randomly select 30g samples from the same batch of products and inspect them according to Table 1. Table 1 Identification and inspection
Required clause number
Test method clause number
Filling point
Resistivity (p)
Optical anisotropy (An)
Extraordinary refractive index (ane)
Dielectric anisotropy ()
Dielectric constant (e)
Reading voltage (V10,0,20)
Saturation voltage (V90,0,20)
4.4.3 Determination of failure
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Continued Table 1
Required clause number
Test method clause number
If the test sample passes all the inspections or tests listed in Table 1, the identification and inspection is qualified; if one item is unqualified, the qualification of identification will not be granted.
4.5 Quality consistency inspection
4.5.1 Composition of inspection batch
An inspection batch shall consist of all products with the same liquid crystal monomer, the same formula, produced under basically the same conditions and submitted for inspection within the same period.
4.5.2 Quality consistency inspection form
Quality consistency inspection Randomly select 30g samples from the same batch of products and inspect them according to Table 1. They shall all meet the requirements of this specification.
4.5.3 Non-conformity
If one or more of the inspections specified in Table 1 fail, the batch shall be deemed unqualified and the acceptance and delivery of the products shall be stopped. The contractor may take corrective measures and resubmit the inspection after correcting the defects. The resubmitted inspection batch shall be separated from the normal batch and the re-inspection batch shall be clearly marked. If the re-inspected batch still fails, the batch shall be deemed unqualified. 4.6 Packaging inspection
The packaging and marking requirements specified in Chapter 5 shall be inspected by visual method. 4.7 Inspection method
4.7.1 Inspection of state
Inspect by visual method, and it shall meet the requirements of Article 3.3. 4.7.2 Inspection of appearance
Inspect by visual method, and it shall meet the requirements of Article 3.4. 4.7.3 Measurement of melting point
4.7.3.1 Principle overview
The melting point and clearing point of liquid crystal are measured by differential thermal analysis. The sample and reference material are heated or cooled under the same conditions. The program control of the furnace temperature is monitored by a temperature-controlled thermocouple. The temperature difference between the sample and the reference material is usually measured by two relatively connected thermocouples. The two junctions of the thermocouple are in contact with the sample and the reference material respectively. The electromotive force of the thermocouple is proportional to its temperature difference. The differential electromotive force is amplified and recorded by the detection instrument (such as XY recorder), and the differential thermal analysis curve, namely △T～T(1) graph, can be obtained. When the sample and the reference are heated or cooled under the same conditions, if the sample does not produce any thermal effect, that is, the sample temperature is equal to the reference temperature T, then AT=Ts-I, =0, and the XY recorder does not indicate any differential thermoelectric force. If the sample has an endothermic or exothermic effect, then 4T=Ts-T, the differential thermoelectric force is less than zero or greater than zero, and the differential thermal analysis curve of AT=F(T) can be obtained on the XY recorder. Since the liquid crystal absorbs heat when the phase change occurs (heating process), two absorption peaks of 1000 will appear on the differential thermal analysis curve. According to the position of these absorption peaks, the phase change temperature of the liquid crystal can be accurately determined, thereby obtaining the melting point and clearing point, etc.
4.7.3.2 Measuring equipment
Differential thermal analyzer (DSC).
4.7.4 Measurement of melting point and clearing point
Measure the melting point and clearing point according to the measurement method in 4.7.3. 4.7.5 Measurement of viscosity
4.7.5.1 Measuring equipment
a. Constant temperature bath, accuracy ±0.1C;
b. Semi-micro capillary viscometer, capacity 8mL, accuracy ±1mm2/s; t. Stopwatch
4.7.5.2 Test steps
Put the capillary viscometer with the liquid crystal to be tested in a constant temperature chamber (20) for half an hour, use an air pump to suck the liquid crystal to the scale, remove the air pump to allow the liquid crystal to flow through the capillary by itself, and at the same time, time the time t for the entire flow to be completed (should be between 100 and 200 s), and calculate the viscosity according to formula (1).
Where: — kinematic viscosity of the liquid, mm2/s; c——viscometer constant, mm*/s';
— time for the liquid to flow out, 5c
4.7.6 Measurement of resistivity (g)
4.7.6.1 Measurement method
Insert the conductivity electrode into the liquid crystal to be tested, and use an ultra-high resistance tester to measure its resistance R. The area of the platinum sheet of the conductivity electrode and the distance between the two platinum sheets are known, and the resistivity of the liquid crystal to be tested can be calculated according to formula (2). O=RS/...
Where: 2——resistivity, n-cm
R-—resistance, α;
S—area of the platinum sheet of the conductivity electrode, cm2;
1—the distance between the two platinum sheets of the conductivity electrode, cm. 4.7.6.2 Measuring equipment
.Ultra-high resistance tester (capable of measuring resistance greater than 1017): b. Conductivity electrode.
4.7.6.3 Measuring steps
Use a clean and dried 50mL beaker to take 30ml of the newly mixed liquid crystal to be tested, keep the temperature constant at 20±2℃, measure the resistance with a conductivity electrode, record its resistance value R, and calculate the resistivity according to formula (2). 4.7.6.4 Error
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The accuracy of the measurement by this method mainly depends on the accuracy of the ultra-high resistance tester. When the resistivity is between 1×10~2×1011ncm, the error is generally not more than ±10%, and when the resistivity is between 1×10112×102ncm, the error is not more than 20%.
4.7.7 Measurement of optical anisotropy (An)
4.7.7.1 Measurement method
In liquid crystal medium, linear polarized light with the vibration direction of the light vector perpendicular to the long axis of the liquid crystal molecule is called ordinary light (light), and the ratio of the speed of light in vacuum to the speed of ordinary light in liquid crystal medium is called ordinary light refractive index (n). Linear polarized light with the vibration direction of light vector parallel to the long axis of the liquid crystal molecule is called extraordinary light (e light), and the ratio of the speed of light in vacuum to the speed of extraordinary light in liquid crystal medium is called extraordinary light refractive index (n). Optical anisotropy (△n) is the difference between the refractive index of extraordinary light (n) and the refractive index of ordinary light (n), that is:
An=ne-
Evenly coat a layer of vertical alignment agent on the optical glass surface and the frosted glass surface of the Abbe refractometer to make the liquid crystal molecules to be measured vertically arranged in a certain direction, and stick a polarizing plate on the eyepiece of the Abbe refractometer. When the incident direction of light, the arrangement direction of liquid crystal molecules and the polarization direction of the polarizing plate are as shown in Table 2, measure n and n respectively. Calculate An according to formula (3). Table 2n 1. Relationship between incident direction of light, arrangement direction of liquid crystal molecules and polarization direction of polarizing plate ne (nj)
Light incident direction
Liquid crystal molecule arrangement direction
Polarization direction of polarizing plate
4.7.7.2 Measuring equipment
a. Abbe refractometer;
1. Cryostat.
4.7.7.3 Measurement steps
n,(ng)
Evenly apply the vertical alignment agent on the optical glass and frosted glass surface of the Abbe refractometer and let it air dry naturally. Adjust the polarization direction of the polarizer on the eyepiece to the direction when measuring n. as shown in Table 2. Drop the liquid crystal to be tested on the treated glass surface, start the low temperature constant temperature, and when the temperature is constant at 20℃, adjust the eyepiece field of view so that the crosshairs are clearly imaged, and rotate the adjustment knob to find the position of the light and dark dividing line in the eyepiece field of view, so that the dividing line is located at the center of the crosshairs. The 1 of the liquid crystal to be tested can be read on the scale below the eyepiece field of view. Rotate the polarization direction of the polarizer on the eyepiece by 90, rotate the adjustment knob to find another light and dark dividing line in the eyepiece field of view, and make the dividing line at the center of the crosshairs. At this time, the value shown on the scale below the eyepiece field of view is the n of the liquid crystal to be tested. Then, △n is obtained from formula (3). The measurement accuracy of this method is ±0.005. 4.7.8 Measurement of extraordinary light refractive index (n,) n is measured according to the measurement method in 4.7.7. . 4.7.9 Measurement of dielectric anisotropy (4e)
4.7.9.1 Measurement method
Under the action of an electric field, the crystal molecules are oriented with the electric field, and their molecular long axis is consistent with the direction of the electric field (liquid crystal>0). At this time, the director of the liquid crystal is parallel to the electric field, and the measured dielectric constant is called e. On the contrary, when the liquid crystal director is perpendicular to the electric field, the measured dielectric constant is called E1. Figure 1 is a schematic diagram of the liquid crystal dielectric anisotropy measurement device. 15
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Precision LCR meter
Computer
Figure 1 Diagram of the measurement device for dielectric anisotropy of liquid crystal The liquid crystal box used for measurement is a parallel box, and the empty box capacitance is C. . The liquid crystal to be tested is injected into the liquid crystal box, and C1 is measured when the liquid crystal director is perpendicular to the electric field, and C is measured when the liquid crystal director is parallel to the electric field. e/, e1 and Ae are calculated by equations (4), (S) and (6). 1=C1/C
e= Cn/C
Ae=E-ET
The liquid crystal molecules near the two inner surfaces of the liquid crystal box are affected by the boundary conditions. Under the action of the electric field, their molecular long axis (liquid crystal with e>0) may not be completely consistent with the direction of the electric field. In order to keep the long axis of the liquid crystal molecules completely consistent with the direction of the electric field, a very high voltage must be applied, which is difficult to measure. Therefore, the extrapolation method shown in Figure 2 is used to calculate the capacitance C when the voltage is infinite, which ensures the accuracy of C measurement. In Figure 2, the ordinate is the capacitance (C) and the abscissa is 1/V. The capacitance C is linearly related to 1/V. The intersection of the extended oblique line and the ordinate is the calculated capacitance Ch when the voltage is infinite. Cr
Figure 2 Extrapolation method to calculate the capacitance when the voltage is infinite/Schematic diagram 4.7.9.2 Measurement equipment
a. A precision LCR meter;
b. A computer.
4.7.9.3 Preparation of test tube
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Photoetch a 1cm2 circular electrode pattern on the conductive glass (ITO glass), and make a parallel test box as shown in Figure 1, with a box thickness of 7uma
4.7.9.4 Measurement steps
a. Measure the empty basin capacitance C of the test box.
b. Inject the liquid crystal to be tested into the test box, apply a voltage of 100mV (square wave, 1.6kHz) to the liquid crystal box, and measure C1c. Apply the measurement voltage to the liquid crystal box, draw a C~1/V graph, and the extrapolated oblique line intersects with the vertical axis to obtain the capacitance C when the voltage is infinite.
The measured C , C and the extrapolated C/ are substituted into formula (4) to calculate I, e/ and Ae. The accuracy of measuring 4e by this method is:
4s>10 error ±0.5;
Ae<10 error ±.3.
4.7.10 Measurement of dielectric constant (e1)
Measure the dielectric constant (e1) according to the measurement method in 4.7.9. 4.7.11 Measurement of threshold voltage (Vj0.0,20) 4.7.11.1 Measurement method
In a normal self-type liquid crystal display device, the effective value of the applied voltage when the change of the light transmittance or reflectance of the display part reaches 10% of its maximum is called the threshold voltage (V), and the effective value of the applied voltage when the change of the light transmittance or reflectance of the display part reaches 90% of its maximum is called the saturation voltage (V%). When the driving voltage of the liquid crystal display device gradually increases, its transmittance gradually changes, and the electro-optical response curve is shown in Figure 3. T
100%90%
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Figure 3 Electro-optical response curve of liquid crystal display device 4.7.11.2 Measurement equipment
The schematic diagram of the measurement equipment is shown in Figure 4.
a. Incandescent lamp;
b Collimator;
c. Vibration plate;
d, small-beat light intensity measuring instrument;
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e. Signal generator:
f, computer.
Incandescent lamp
Collimator
4.7.11.3 Measurement steps
Image grip
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Signal generator
Figure 4 Schematic diagram of electro-optical response curve measurement device Computer
Small angle light intensity
Micro Sheng instrument
Inject the liquid crystal to be tested into the liquid crystal box (TN box, the box thickness is 7um), the directions of the polarizers P and Pz form a 90° angle, the incident direction of the light is perpendicular to the surface of the liquid crystal box, and the driving voltage of the liquid crystal box is provided by the signal generator (square wave, 32Hz). The voltage is increased by 1V every 35g, and the scanning time is 35s/V. When the voltage gradually increases, the continuous change of the transmittance is measured. The light intensity passing through the liquid crystal box is measured by the small angle light intensity measuring instrument and input into the computer. After processing, the electro-optical response curve of the liquid crystal box and the values of V. and V. are obtained. The entire measurement process is carried out at 20℃. The measurement error is ±0.05V. 4.7.12 Measurement of saturation voltage (Vo0,0,20) Vg0,0,20 is measured according to the measurement method in 4.7.11 5 Delivery preparation
5.1 Packaging and packaging
Sealed packaging with borosilicate hard glass bottles.
5.2 Transportation and storage
Transportation can be carried out by any auxiliary means, and light oxygen is used during loading and unloading. The product should be stored in a dry room without direct sunlight. 5.3 Marking
A label should be attached to the packaging container of the product, and the following contents should be indicated: a. Product brand;
b, net weight;
c. Production date;
d. Production unit.
6 Notes
6.1 Intended use
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The liquid crystal materials specified in this specification are intended to be used in TFT-LCD liquid crystal display devices. 6.2 Contents of order documents
The following contents shall be stated in the contract or order form: a. Name and number of this specification:
b. Brand of material:
c. Weight of material:
d. Special packaging requirements;
e. Special marking requirements:
f. Others.
Additional remarks:
This specification is proposed by the Ministry of Electronics Industry of the People's Republic of China. This specification is issued by the China Electronics Technology Standardization Institute! 1. This specification was drafted by Tsinghua University.
The main drafters of this specification are: Xu Shouti, Tang Hong, Yao Naiyan, Liu Yun. 9
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