JPS60210493A - Recording material - Google Patents

Abstract

PURPOSE:To enable to record information and optically read the recorded information, by applying thermal energy to a recording material to generate a thermal hysteresis. CONSTITUTION:Thermal energy is applied to an amorphous substance having a change of specific heat at a glass transition temperature [DELTACp (J.K<-1>.g<-1>)] satisfying the relationship of DELTACp>=0.86exp(-Tg/394.3) and a change of specific heat per one mole of an average molecular weight of molecular component units constituting the substance at the glass transition temperature [M'.DELTACp (J.K<-1>. mol<-1>)] satisfying the relationship of M'.DELTACp>=10.9 to generate a thermal hysteresis. The recording material is once heated to a temperature not lower than the glass transition temperature, followed by slowly or rapidly cooling to obtain a uniform state. After this pretreatment, the positions for recording in the material are irradiated with IR rays, laser light or the like to partially heating the material to a temperature not lower then the glass transition point, followed by rapidly or slowly cooling to impart a thermal hysteresis, whereby parts differing from other parts in density or refractive index are provided, resulting in performing recording.

Description

Detailed Description of the Invention (Field of Application) The present invention uses optical recording materials, more specifically, generates a difference in thermal history by applying thermal energy using a laser or the like, and changes in refractive index, density, etc. due to this. The present invention relates to a recording material that records information using the technology and can be read optically.

(Prior Art) Conventionally, optical recording materials that utilize thermal state changes of substances have been used that utilize changes between the amorphous state and the crystalline state of chalcogenide-based substances. Chalcogenide glass is used as an optical recording material in the form of a vapor-deposited film.

When obtaining an amorphous film by vapor deposition, a uniform thin film is obtained by solid solutionizing certain components in a vacuum and rapidly cooling them. However, since chalcogenide glass has a wide variety of constituent elements, it is difficult to obtain a thin film with a uniform composition. In addition, the pulgenide-based glass thin film has a drawback that the initial optical density of the unrecorded state is large, and when the contrast is high, the readout efficiency becomes extremely low. Another problem is that chalcogenide glass contains arsenic, which is known to be a poison.

(Summary of the present invention) In view of the current situation, the present inventors conducted various studies in order to provide a recording material with excellent homogeneity. , or for substances with a large change in specific heat per mole of the average molecular weight of the molecular constituent units that make up the molecule at the glass transition temperature, when thermal energy is applied to the substance to create a thermal history, this causes a large change in the refractive index or density. This led to the development of a new recording material that solved the conventional problems.

That is, in an amorphous substance, the change in specific heat at the glass transition temperature (ΔCp: unit J-1) is ΔCp≧0.86.
exp (-"7394.3) or the change in specific heat per mole of the average molecular weight of the molecular constituent units constituting the substance at the glass transition temperature (M-ΔCp: unit J-@n'
10! -)M-ΔC1)≧10.9 When thermal energy is applied to an amorphous material to generate a thermal history, the change in refractive index and density is extremely large. However, for substances that do not satisfy the condition -11,
The changes were significant: 1) I discovered something important and was able to provide new recording materials.

(Specific Description) Next, the present invention will be described in detail. Normally, when an amorphous polymer is heat-treated at a temperature slightly lower than its glass transition temperature, it is heated at a temperature higher than its glass transition temperature and then rapidly cooled.
The island molecules in a glassy state with a higher density can be obtained than in the case of molasses. This phenomenon is called volume relaxation phenomenon.

That is, when a material that has been heated to a temperature higher than the glass transition temperature and then rapidly cooled is subjected to heat treatment at a temperature about 10° C. lower than the glass transition temperature, the density gradually increases from 1 to a certain equilibrium value. Furthermore, when the heat-treated material is heated to a temperature higher than the glass transition temperature and then rapidly cooled, the density returns to approximately the value before the heat treatment, and this change in density is reversible.

Similar density differences are observed between samples cooled quickly and slowly from temperatures above the glass transition temperature. In addition, even if the cooling rate and temperature are the same, there is a difference between cooling from a temperature higher than the glass transition temperature under high pressure to below the glass transition temperature and then returning to normal pressure, and a temperature higher than the glass transition temperature at normal pressure. A similar density difference is observed between those cooled from . All of these phenomena are due to the fact that the glass transition is a relaxation phenomenon.〇This density difference is usually very small? ” 1 year old. For example, when polystyrene is cooled for 73 minutes at 1°C, the density difference between the glass obtained when it is cooled at 1°C for 71 days is approximately 0.1 s %, and 1 s % under normal pressure and 600 atm.
The difference in density of the glass obtained by cooling at °C/3 minutes is only about 0.6 cm for polystyrene (Potimer
Journat, 2, 644 (1971)) Q The difference in refractive index based on this density difference is the difference between those cooled at a slow rate of 1°C/day and those cooled rapidly.
oi, and has not been used as an optical recording material in the past.

-5= As a result of the inventors' studies on polymethyl methacrylate, polycarbonate, polyvinylcarbasol, polyz-thylimide, polyethersulfone, etc., it was found that when these polymer compounds are heat-treated at a temperature slightly lower than the glass transition temperature, A material with a large difference in refractive index was obtained compared to that obtained by heating and rapidly cooling at a temperature higher than the glass transition temperature.

Furthermore, the specific heat change at the glass transition temperature of these polymers is different from that of polymers that do not show large refractive index changes (e.g.
It was discovered that this material is larger than polyvinyl chloride, polystyrene, polyethylene terephthalate, etc.).

The present inventors studied the relationship between this refractive index change and enthalpy relaxation by the amount of lead, and found that the specific heat change at the glass transition temperature Tf is
If the value is larger than a certain value, the difference in density and refractive index between the material heat-treated at a temperature 10 to 20°C lower than Tf and the material rapidly cooled from a salinity of -L above Tf is sufficient to be used as an optical recording material. I discovered something.

In other words, the inventors have determined that the amount of change in the specific heat at constant pressure at the glass transition temperature '16-, that is, the difference Δcp between the values obtained by extrapolating the specific heat at constant pressure in the glass state and the liquid state to Tt, is Tt.
fi When expressed as absolute temperature, ΔCp = Q, 805 for many polymers and low-molecular substances with relatively small polarity.
It has been found that it is expressed by the relational expression exp (TV/394.3) -■. Table 1 and Figure 1 show the Tt and ΔCp (values calculated from JK-1r'l and 0 formulas) of ordinary polymers. The standard deviation was 0.052.

(Left below) Also, B, Wunderl Ich (J, Phys.
, Cheffl, 64.1052 (1960)), T per mole of the average molecular weight of the molecular constituent units of a polymer.
The change in specific heat at t, i.e. the molecular weight per repeating unit t” M sThe number of constituent units contained in the repeating unit is n
When, M-ΔCp/n=M-ΔCp (J K-
It is said that the value expressed in 'mol-'') is almost constant regardless of the substance. However, the method of counting the number of constituent units n in this document is a little ambiguous. Therefore, the inventor of the present invention etc. is the definition 1- of all the ways to count n as follows.

That is, the structural unit constituting the polymer in the present invention is a block sandwiched between single bonds that can rotate once in terms of atoms or groups in the main chain, for example, -C+.

-c=:c -, To -, -s -, -co-, -5
o2+.

For the side chain, -CH3, -C1, -F-
Only one clo is connected to the main chain with a single bond such as OH,
IIX small side chain groups such as elements such as N and S and their hydrides or halogen elements were set to 0, other factors were set as n, and M·ΔCp/n = M·Δ was calculated. The results are shown in Table 2 and Figure 2, and the average value is 9.75J K-
"mol-'. The standard deviation was 0.55 for those shown in Table 2.

(The following is a blank space) 10- Furthermore, the present inventors have determined that a substance that satisfies both of these two rules and a substance that deviates from one or both of these rules by a certain amount at a temperature 10 to 20 degrees Celsius lower than the Tr of the substance. As a result of comparing the refractive index and density after heat treatment with the magnitude of the difference in refractive index and density of the material rapidly cooled from a temperature higher than Tv, it was found that materials with large density differences and refractive index differences have ΔCp
(J-to, -'・t-1).

ΔCp≧0,86 exp (Tr/394.3)
or MΔcp (J − to −′
・mol-1) was found to be in the range of M-ΔCp/n = M-ΔCp≧10.9 These results probably indicate that ΔCp
It is considered that a large value of +M·ΔCp means that the enthalpy and specific volume in the glass state can be relaxed and the density is large. Of course, considering that the relationship between the molecular refraction R and the molecular weight Ms"lB degrees ρ per 0% refractive index repeating unit is expressed by the Lorentz-Lorentz equation, in order to obtain a larger refractive index change, the refractive index is It goes without saying that a polymer with a large thickness (R/M, that is, a large specific refraction) is preferable, and it is natural that such a polymer generally corresponds to a polymer with a large polarity.

The present inventors have also found that Equation 0, which has the same form as Equation (2), holds true for the change Δα in the coefficient of body expansion at sTf.

Δα=7.72xlO″exp(-Tr/394.3)
(K-1)・−・−■And Δα≧8.55 x I
Cr' exp (-Tp/394.3) (K' We found that the substance that is one has large changes in density and refractive index.The problem is that measuring the coefficient of expansion of a body is more difficult than measuring specific heat. .

In addition, in order to use it for optical recording, it is necessary that the glass transition temperature of the material is 50°C or higher, and furthermore, the glass transition temperature of the material must be 85°C or higher.
The zero glass transition temperature is preferably 50°C or higher.
Below this, the stability at room temperature is poor, and in order for the recording state to be stable for a long period of time, the glass transition temperature needs to be 50° C. or higher, more preferably 85° C. or higher.

13- The polymer that meets these conditions can be selected from, for example, polymethyl methacrylate, polycarbonate, polyvinylcarbazole, polyetherimide, polyethersulfone, and the like.

When the present invention is used as an optical recording medium or an optical recording medium, the material of the present invention is formed into a film, sheet, tape, monofilament, or other shape depending on the purpose. The medium can be composed of a single phase of the copolymer of the present invention, but other base materials such as polyester and nylon can also be used by logging.

In addition, thermal energy is applied to optical recording materials to create history differences, but depending on the wavelength of the light used to apply thermal energy, compounds such as dyes may be added to optical recording materials to improve sensitivity. It can also be added in small amounts to the ingredients used.

When recording on the optical recording material of the present invention, the molded recording material is heated to a temperature above the glass transition point and then slowly or rapidly cooled to obtain a uniform state through pretreatment.
Then, the position to be recorded is irradiated with infrared rays or laser light, etc. to partially raise the temperature above the glass transition point, and then rapidly or gradually cooled to give a thermal history different from that of the pretreatment. This forms portions with different densities and refractive indexes, and recording is performed using these portions.

Therefore, pretreatment gives a thermal history that is in contrast to the thermal history at the time of recording, and when rapidly cooling the recording medium during recording, the recording medium is heated to above the glass transition point in a heating furnace or laser beam, and then slowly cooled. The heat treatment is carried out at a temperature slightly lower than the glass transition point, generally a to 50° C., preferably 5 to 20° C. lower than the glass transition point. Slow cooling or heat treatment under pressure can also be carried out.

On the other hand, when slow cooling is performed during recording, rapid cooling is performed in the preliminary process.

Glass transition usually occurs over a wide range of temperatures.

Therefore, this must be taken into consideration when heating the optical recording material of the present invention above its glass transition temperature to cause a transition.

Generally, heating during pretreatment or recording is preferably performed at a temperature of 5° C. or higher, preferably 10° C. or higher, than the glass transition temperature. There is no particular temperature limit, and the process is carried out below the decomposition temperature of the optical recording material.

Recorded recording media are usually stored at a temperature of 3° below the glass transition point.
It is carried out at a temperature lower than 0°C, preferably lower than 50°C.

In addition, reading a record involves irradiating it with visible light, laser light, etc., and measuring changes in the refractive index and reflectance of the recorded area, changes in the direction of light reflection based on surface irregularities, or changes in light transmission speed. This can be done by

Next, the present invention will be explained by examples, but the present invention is not limited thereto.

Example 1 Polyetherimide represented by the following formula (glass transition temperature 4
87°K) ・0(3) was heated to 492°, a temperature higher than the glass transition source If, and then rapidly cooled. Sample A and this rapidly cooled sample were heat-treated at 4770°C, which is about 10°C lower than the glass transition temperature, for 5 hours. When we measured the amount of change in the refractive index of sample B, we found an extremely large change of 0.021.The change in specific heat of this polymer at the glass transition temperature is ΔCp = 0.
．． 26 JloK-f from Figure 1 pre-m Sarel 1 cp (
The D value is 0.23 J/', which is 1.13 times as large as -y K. Also, according to the value of ΔCp, the number n of molecular constituent units of this polymer is n = 81: M
=74.1 and M-ΔCp==193J10K・ml
It can be seen that this value is extremely large compared to the general polymer shown in FIG.

Example 2 Polymethyl methacrylate (glass transition temperature 3840K)
This film was heated to a temperature of 400° above the glass transition temperature and then rapidly cooled.

This rapidly cooled film was heated to 3740K and heat treated for 5 hours. When the refractive index of the film obtained by rapid cooling and the film after heat treatment was measured, a change in refractive index of 0.0071 was found. The change in specific heat at the glass transition temperature of this film is ΔCp=0.34 Jlo-
The values o and a expected from FIG. 1 for f are larger than -9 for OJ70. Also, the value of i・ΔCp is 1
At 1.3J10, -mole showed a larger value than that of the general face molecule shown in FIG.

In addition, the number n of molecular constituent units is n = 3 and M-33
, 4 is 0. Also, Δα is 1 in 3,30 x 10"-', and the value obtained from the formula 0 is 2.(11 x 10-' K-1
Example 3 Polyvinyl carbazole (glass transition temperature 476'K)
Refraction of sample A, which was prepared by heating the polymer to 493 cK above the glass transition temperature and then quenching it in the same manner as in Example 1, and sample B, which was heat-treated at 4660 cK, which is lower than the glass transition temperature, for 5 hours. The weight was measured at 60. (
There was a big difference between 1 and 5. The specific heat change at the glass transition temperature is ΔCp = 0.26 J/81 at 0K-9
The expected value from the figure is 0.24 J/', which is sufficiently large compared to -f @ftfdik, M-1jcp = 16.7
, J/''K-mol, which is 18-mol, which is sufficiently large compared to general polymers (see Figure 2).

In addition, the number n of molecular constituent units is n = 3 and M = = 64
．． It is 4.

Example 4 A whole film of polycarbonate (glass transition temperature 426°K) was prepared, and this film was heated to a temperature of 443°1 (above the glass transition temperature) and then rapidly cooled. This rapidly cooled film was heat-treated at 416° for about 5 hours. When the refractive index of the rapidly cooled film and the heat-treated film were completely measured and compared, a difference of 0.009 was rarely found.The change in specific heat of this film at the glass transition temperature was Δcp = 0.26 J/'
The expected value from Figure 1 for K puff is 0.27 JloK
-f, but i・ΔCp=11. OJl
oKamole showed a larger value than that of general polymers.

In addition, the number n of molecular constituent units is n=6 and M==42.
It is 4. Further, Δα is 1 in 3.13 x lo-', which is 1.19 times the value calculated from the equation 0, which is 2.62 x 10-', which is a large value.

Example 5 A polymer of polyether sulfone (glass transition temperature 497°1<) represented by the following formula was heated to a temperature of 513° above the glass transition temperature and then rapidly cooled in the same manner as in Example 1. 1. Measurement and comparison of the refractive index of the sample and a sample heat-treated with this sample '5r4870 for about 5 hours 1. But 0.00
There was a difference of 9. The change in specific heat at the glass transition temperature is ΔCp
= 0.24 JloK-y, the value expected from Figure 1 0.23 Although it shows almost the same value as JloK-f, M-ΔCp = 13,9 JloK-mo heat compared to general diurnal molecules. 〇The number n of structural units is n = 4 and M: 5B, 0. Comparative Example 1 A film of polyvinyl chloride (glass transition temperature 349°K) was created, and this film When we measured and compared the refractive index of a film that was heated to 373° above the glass transition temperature and then rapidly cooled, and a film that was heat-treated at 339° for about 5 hours, the difference was 0.001, which was almost the same. The change in specific heat of this film at the glass transition temperature is ΔCp = 0.30 Jlo -9, which is the value expected from Figure 1, 0.33 Jlo -f, which is slightly smaller than, but on the same level. For i・Δcp, load・ΔCp = 9,4 JloK・mole and the second
Comparative Example 2 Polyethylene terephthalate (glass transition temperature 340 °
A sample in which the polymer of K) was heated to a temperature of 345' above the glass transition temperature and then rapidly cooled, and this sample was heated to a temperature of 3300
A comparison of the refractive index with a sample heat-treated for about 5 hours in a resin revealed that the difference was o, o o o, and no difference was observed.The change in specific heat of this polymer at the glass transition temperature is ΔCp
= 0.34 J/' to -9, which coincided with the expected value from Figure 1 to 0.34 J/' to -t. Also M・Δcp
For 21-mole, M-ΔC1)=9.3 J/OK-mole, which agrees with the value shown in FIG.

In addition, the number of molecular constituent units n = 7 and M = 27.5
Some 0

[Brief explanation of the drawing]

Figure 1 shows the relationship between the change in specific heat and the glass transition temperature of a general polymer at the glass transition temperature, and Figure 2 shows the glass transition temperature of a typical polymer in terms of moles of molecular constituent units. FIG. 3 is a diagram showing the relationship between specific heat change and glass transition temperature at . Patent applicant Mitsubishi Yuka Co., Ltd. agent Patent attorney Katsutoshi Furukawa (and 1 other person) -22= Figure 1 Figure 2 joo 300 400

Claims (1)

[Scope of Claims] A thermal energy storage device characterized by having a glass transition temperature of 3231 or higher and being formed of an amorphous polymer shown in (1) or (2) below. Recording materials for recording and reading information by changing physical properties by
: unit J unit -1・rl) is a polymer body represented by the following formula -T? ΔCp≧o, 5sexp(/) 394.3 Tt Ni glass transition temperature unit “K (2) Specific heat change (M・ΔCp: unit J− to −
"・mol-") is represented by the following formula: polymer M・Δcp≧10.9