JP2000212269A - Polycarbonate resin, substrate for optical information recording medium prepared by using the same, and optical information recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a thermally stable polycarbonate resin by selecting a polycarbonate resin which contains a specific low-molecular compound in a specified concentration and from which the low-molecular compound vaporizes in a specified amount when the resin is heated at a specified temperature and degree of vacuum for a specified time. SOLUTION: A low-molecular compound represented by the formula in a concentration of 0.1-0.35 wt.% is contained in a polycarbonate resin, and the amount of the low-molecular compound vaporizing, when the resin is heated at 350 deg.C under a vacuum of 1 mmHg for 20 min, from the resin is 0.2 wt.% or lower of the amount of the compound present before the heating. The resin is prepared by reacting an aqueous solution of a metal salt of an aromatic diol with phosgene in emulsion in a molar ratio of the aromatic diol to phosgene of 0.70-0.96 in the presence of an inert organic solvent, a polymerization catalyst (e.g. a trialkylamine), and a mol.wt. regulator (e.g. p-t-butylphenol) in an amount of 0.5-10 wt.% of the diol. In the formula, R1 is an aromatic diol residue; and R2 is a monophenol residue.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polycarbonate resin (hereinafter sometimes referred to as "PC resin"), and more particularly to a polycarbonate resin suitably used for a substrate for an optical information recording medium such as an optical disk. . Further, the present invention relates to a method for producing the above polycarbonate resin, a substrate for an optical information recording medium using such a polycarbonate resin, and an optical information recording medium using the same.

[0002]

2. Description of the Related Art An optical recording system capable of non-contact recording and reproduction has a feature that it is more resistant to scratches and dirt than a conventional magnetic recording system, and greatly contributes to an increase in storage capacity. . The recording medium of this system is formed by forming an information recording layer on a transparent substrate such as a PC resin. P
C resin is a suitable material as a substrate material of the above-mentioned information recording medium because it has excellent heat resistance during melt molding, small dimensional change after molding, and excellent mechanical properties. Optical recording media are required not only to have problems with the characteristics of the substrate itself, such as birefringence and mechanical characteristics, but also to have a small number of molding defects such as pit shifts and mold release unevenness that occur when the substrate is manufactured. When a PC resin is used as the substrate, the substrate is usually molded at a higher temperature in order to extremely dislike the birefringence remaining on the transparent substrate. At that time, a bit error caused by adhesion of the generated low-molecular volatile matter to a stamper or a replica causes an important problem, and reduction of the amount of volatilization is an important proposition.

Heretofore, there have been many documents discussing low-molecular-weight compounds contained in PC resins suitable for such applications. For example, a method for reducing low molecular weight compounds by improving the polymerization method is disclosed in Japanese Patent Publication No. Hei 6-23243,
It is described in JP-A-336522, JP-A-3-109420 and the like. A method for removing low molecular weight substances from the produced polymer by acetone extraction is disclosed in
No. 78929, JP-A-64-6020 and JP-A-4-306227.

[0004]

In the prior art including the above-mentioned known documents, how to reduce low molecular weight compounds from the PC resin itself is discussed. We did not consider the mechanism by which volatiles evaporate, and it was undeniable that there was room for reconsideration in this regard. In particular, the means such as acetone extraction required for the reduction of low molecular weight components is relatively satisfactory in its effect, but it requires a complicated process such as acetone extraction, which poses an industrial problem. There were many. For example, when performing acetone extraction, not only the extraction step, but also a step of separating acetone and a step of recovering acetone are required, which is extremely complicated industrially, and the production cost is correspondingly increased. It is not preferable because it rises. In addition, even if low-molecular compounds were reduced by acetone extraction, volatile components generated by heating were not necessarily reduced. The present invention has been made in view of such circumstances, and is suitable for a substrate of an optical recording medium and the like, and uses a low-molecular-weight compound, particularly, a polycarbonate resin having a reduced volatile component, and uses complicated means such as acetone extraction. It is an object of the present invention to provide a method for producing such a resin without any problem.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies on a PC resin suitable as a substrate for an optical recording medium, and have found that the presence of a specific compound in the PC resin is important. It was found that the existence form was important together with the presence or absence of. In other words, in addition to the solubility (compatibility) of the specific low-molecular compound in the molten PC resin, the decomposition reaction of the specific low-molecular compound in the PC resin is suppressed (that is, a thermally stable PC resin is used). Get)
Is also important, that is, the low-molecular compound by-produced during the production of the PC resin is thermally stabilized so that the low-molecular compound volatilizes even though a certain amount of the low-molecular compound is contained. The inventors have found that the ratio can be reduced, and have previously proposed it as Japanese Patent Application No. 10-212462. The present inventors have further studied and obtained new knowledge on the amount of an acceptable low molecular weight compound of a PC resin suitable for a substrate of an optical recording medium and the like, and by reducing the molar ratio of polyhydric phenol to phosgene, It is known that the terminator reduces the ratio of bischloroformate, which is a precursor of the low molecular compound added to both ends of the polycarbonate oligomer, and consequently reduces the amount of the low molecular compound,
The present invention has been completed.

That is, a first gist of the present invention is a polycarbonate resin obtained by polymerizing an aromatic diol and a carbonate-forming compound with a monophenol as a molecular weight regulator. When the content of the low-molecular compound represented by the general formula (1) is 0.
When the polycarbonate resin is heated at 350 ° C. under a vacuum of 1 mmHg for 20 minutes,
The polycarbonate resin is characterized in that the proportion of the low-molecular compound volatilized is 0.2% by weight or less of the low-molecular compound contained in the polycarbonate resin.

[0007]

Embedded image (However, R ¹ represents an aromatic diol residue, and R ² represents a monophenol residue.)

The present invention also provides an organic phase containing an organic solvent,
After contacting water and an aqueous phase containing a metal salt of an aromatic diol under emulsifying conditions to form an emulsion, the emulsion and phosgene are reacted with the molar ratio of the aromatic diol to phosgene. The polycarbonate resin according to claim 1, which is produced through a step of obtaining an oligomer by contacting the mixture at a ratio of 0.70 to 0.96 and under a condensation reaction condition under a mixing condition weaker than the emulsification condition. A method, a substrate for an optical information recording medium made of the polycarbonate resin, and an optical information recording medium having an optical recording layer provided on the substrate.

The technical point of the present invention is to control the molar ratio of polyphenol to phosgene, which is a raw material for the production of PC resin, so that the terminal stopper is added to both ends of the polycarbonate oligomer by the compound of the above formula (1). A thermally stable polycarbonate by reducing the proportion of the bischloroformate which is the precursor of the compound of formula (1), and consequently reducing the production of the compound of the formula (1) and reducing the proportion of the volatilization to a specific proportion or less. To be made of resin. In the prior art,
Not only was there no recognition of the presence of the specific low molecular weight compound represented by the general formula (1), but the absolute amount of the general low molecular weight compound was discussed only, and the ratio of the volatile amount is important. There was no recognition at all. For example, when low-molecular components are removed by acetone extraction, the absolute amount of the low-molecular compound represented by the general formula (1) decreases, but the rate of volatilization does not decrease.

[0010] While some of them discuss the contents of low molecular weight compounds (Japanese Patent Application Laid-Open No. 3-109420), this is a dimer of a terminating agent formed from a conventionally known terminating agent chloroformate. It is a body, and it depends only on the presence or absence of phosgene, and it is only natural to avoid it.

Looking back at the problem from the above point of view, it is true that not only the volatilization phenomenon of the low molecular weight compound but also the low and high content of the low molecular weight compound are involved. The solubility (compatibility) in the molten polycarbonate resin and the decomposition reactivity of the low molecular compound (that is, the thermal stability of the PC resin) govern the phenomenon in which the low molecular compound volatilizes or does not. It has been found.

That is, low-molecular compounds produced as by-products during the production of PC resin are reduced by employing a special polymerization technique, and are made thermally stable, so that a certain amount of low-molecular compounds in PC resin is obtained. Can be added, and by reducing the molar ratio of polyphenol to phosgene, a terminal stopper is added to both ends of the polycarbonate oligomer. The inventors of the present invention have found that the ratio of the bischloroformate, which is a precursor of the compound of the formula (1), is reduced, and as a result, the amount of the compound of the formula (1) can be reduced.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the compound represented by the above general formula (1) is a compound formed by reacting an aromatic diol with a monophenol via a carbonate-forming compound via a carbonate-forming compound. For example, when bisphenol A is used as an aromatic diol, phosgene is used as a carbonate-forming compound, and pt-butylphenol is used as a monophenol, the low-molecular compound is represented by the following formula (2) It is a compound represented by these. (Hereinafter, this compound is referred to as “PB
P ". )

[0014]

Embedded image (In the formula, t-Bu represents a tertiary butyl group, -Ph- represents a phenylene group, and O-BPA-O represents a bisphenol A residue.)

In the present invention, it is essential that the amount of the low-molecular compound present in the PC resin is 0.1 to 0.35% by weight, preferably 0.15% to 0.3% by weight. %, More preferably 0.2 to 0.25% by weight. To be within the above range, it is possible to cope by lowering the molar ratio of polyhydric phenol to phosgene, as described later.However, when the molar ratio is extremely reduced, chloroformation of the terminating agent occurs, and dimerization of the terminating agent is performed. Undesirably, body formation occurs, and a highly volatile substance is produced.

A PC according to the first aspect of the present invention will now be described.
When the resin is heated at 350 ° C. under a vacuum of 1 mmHg for 20 minutes, the amount of the low-molecular compound represented by the general formula (1) as a volatile matter is 0% of the content of the low-molecular compound before heating. 0.2% by weight or less, preferably 0.15% by weight or less, more preferably 0.1% by weight or less.
Advantageously: That is, although the ratio of the low molecular compound represented by the formula (1) in the PC resin is, of course,
At the same time, its volatilization is a problem. In the conventional method by acetone extraction or the like, although the amount of the entire low-molecular compound is reduced, the volatilization ratio of the existing low-molecular compound has no effect at all.

In the above-mentioned test of the amount of volatilization, if the test temperature is lowered or the test time is shortened, the amount of the low-molecular compound volatilized decreases, and the ratio to the content before heating decreases. Therefore, strict reproduction of the test conditions is an important factor in determining.

The aromatic diol used as a raw material of the PC resin of the present invention is represented by the general formula HO-Z-OH,
Here, Z is one or more aromatic nuclei, and hydrogen bonded to the carbon of the nucleus is a halogen atom such as chlorine or bromine;
It can be substituted with a substituent such as an aliphatic group or an alicyclic group. A plurality of aromatic nuclei may each have a different substituent. Further, a plurality of aromatic nuclei may be bonded by a cross-linking group. This bridging group includes an aliphatic group,
Cycloaliphatic groups, heteroatoms or combinations thereof are included.

Specifically, hydroquinone, resorcin,
Biphenol, bis (hydroxyphenyl) alkane,
Bis (hydroxyphenyl) cycloalkane, bis (hydroxyphenyl) sulfide, bis (hydroxyphenyl) ether, bis (hydroxyphenyl) ketone,
Examples include bis (hydroxyphenyl) sulfone, bis (hydroxyphenyl) sulfoxide, bis (hydroxyphenyl) dialkylbenzene, and derivatives thereof having an alkyl or halogen substituent in the nucleus. Of course, two or more of these aromatic diols can be used in combination.

These aromatic diols and other suitable aromatic diols are described, for example, in US Pat.
No. 14, No. 3,028,365, No. 2,999,
No. 835, No. 3,148,172, No. 3,27
5,601, 2,991,273, 3,2
No. 71,367, No. 3,062,781, No. 2,97
0,131 and 2,999,846, German Patent Publication Nos. 1,570,703 and 2,
Nos. 063,050, 2,063,052, and 2,211,956, and French Patent 1,561,518.

Particularly preferred aromatic diols include 2,2
-Bis (4-hydroxyphenyl) propane (bisphenol A), 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane (bisphenol Z), And 1,1-bis (4-hydroxyphenyl)-
3,3,5-trimethylcyclohexane is included.

The carbonate-forming compound used as a raw material of the PC resin of the present invention is not particularly limited as long as it reacts with an aromatic diol to form a carbonate bond. Phosgene, dimethyl carbonate, diphenyl carbonate, etc. Various things can be adopted. Preferably, they are diphenyl carbonate and phosgene, and it is particularly preferable to use phosgene as a raw material. Here, "using phosgene as a raw material" means not only a case where phosgene is used as a direct raw material of a PC resin but also a case where a phosgene is used as a raw material to produce, for example, diphenyl carbonate and the like, and a PC resin is produced using the same. Including cases.

The low molecular compound represented by the above formula (1) and the PC resin having a reduced volatilization amount, which are the object of the present invention, are as follows:
It can be advantageously produced by reacting aromatic diols with phosgene under specific conditions. That is,
The present inventors have studied the content of the low molecular weight compound in the PC resin obtained as the final product. As a result, surprisingly, by decreasing the molar ratio of the polyhydric phenol to phosgene, the terminal stopper was changed to the polycarbonate oligomer. It has been found that the ratio of the bischloroformate compound, which is a precursor of the compound of formula (1), added to both ends is reduced, and as a result, the amount of the compound of formula (1) can be reduced. Further, as a result of studying the volatility of the compound of formula (1), it was found that there is a correlation between volatility and chlorine contained as an impurity in the raw material phosgene. That is, the impurity chlorine contained in phosgene changes in the form of chlorination of a specific portion of the aromatic diol in the initial stage of the polycarbonate production process during the reaction of the alkali metal salt aqueous solution of the aromatic diol with phosgene and changes to the final process. It has been found that it remains without being used, and is gradually decomposed when subjected to severer conditions than usual in a later molding step.

It is also introduced that polycarbonate having a narrow molecular weight distribution can be obtained by lowering the molar ratio of polyhydric phenol to phosgene, and that dimer of the terminator can be reduced by controlling the timing of addition of the terminator. (JP-A-3-109420). However, what is discussed here is about the deposits in the relatively high molecular weight region such as blow molding, especially the dimer of the terminating agent, and is not related to the resin for disk use as mentioned in the present application, and Equation (1)
Nothing is shown about reducing the amount of compound.

The effect of lowering the molar ratio of polyhydric phenol to phosgene is more remarkable in the case of low molecular weight disc applications because the terminating agent to be added may require almost twice the amount of ordinary injection molding applications. appear. Furthermore, paying attention to the compound of formula (1), it is confirmed that the compound volatilized at the time of disk molding is the compound of formula (1), and no technique capable of quantitatively controlling the compound is suggested in the above-mentioned patent. .

Further, the more the impurity chlorine contained in the raw material phosgene is removed to the extent possible, the more
It has been found that the melt heat stability at the time of molding is improved, and as a result, the low molecular oligomer is less likely to volatilize. For example, phosgene once liquefied for the purpose of purifying phosgene, which is a raw material used as a means, is further passed through an activated carbon tower, and a polycarbonate resin produced using phosgene obtained by adsorbing and removing Cl ₂ contained as a trace amount of impurities is: Although there is no change in the content of the obtained low-molecular compound, the thermal stability of the compound is different, and as a result, it is manifested as a phenomenon that it is difficult to volatilize during high-temperature molding.

In the case of using “phosgene as a raw material” to produce the PC resin of the present invention, the phosgene has a chlorine content of 1500 ppb or less, preferably 1000 ppb or less.
More preferably 500 ppb or less, most preferably 1
It is preferred to use one of not more than 00 ppb. However, if the chlorine contained in the raw material phosgene is sufficiently removed as described above, the melting heat stability at the time of molding the finally obtained PC resin is improved, and as a result, it has excellent properties. It is a PC resin suitable for a substrate for an optical information recording medium. For example, when a PC resin is manufactured using phosgene whose liquid phosgene has been treated with activated carbon to reduce the chlorine content sufficiently, a PC using phosgene that does not reduce the phosgene content is used.
Compared with the resin, even if there is no difference in the content of the compound represented by the general formula (1), the amount of the low molecular compound volatilized during the volatilization test or the amount attached to the stamper during the injection molding is extremely small.

According to the findings of the present inventors, for example, in the production of a PC resin by a melting method using a conventional two-phase interfacial condensation method, chlorine which may be present in the PC resin is derived from chlorine other than chlorine in phosgene. There are also various types such as those derived from a reaction solvent such as methylene chloride and those derived from hydrochloric acid used for washing.However, the amount of chlorine in phosgene is overwhelmingly low, and the amount of low molecular compounds from PC resin is low. It determines the amount of volatilization or the amount of low molecular compounds attached to the stamper,
This is a truly surprising finding.

In the case of "using phosgene as a raw material", phosgene is used in a liquid or gaseous state, but is preferably in a liquid form from the viewpoint of temperature control, and is particularly advantageous when chlorine is adsorbed and removed as described later. . The method for controlling the concentration of chlorine in phosgene to the above range is not particularly limited, and a method of producing phosgene from which chlorine does not remain from the beginning, or a phosgene containing a large amount of chlorine by an ordinary method is used. An example is a method of producing and purifying it to remove chlorine. The latter method is industrially preferable. Methods for removing chlorine from phosgene include adsorption removal using an adsorbent such as activated carbon and separation removal using distillation utilizing a boiling point difference, and any method may be used. However, in the case of distillation removal, the removal order is an extremely low value and a considerable number of distillation stages are required. Therefore, adsorption removal is more advantageous from this point.

As the adsorbent used for adsorbing and removing chlorine in phosgene, various substances such as phenols can be used in addition to activated carbon. When activated carbon is used, various types of activated carbon can be used, such as those for acid gas, basic gas, and general gas, but the preferred activated carbon in terms of chlorine adsorption ability is activated carbon for acid gas. is there. The characteristics of the preferred activated carbon are as follows.

Particle size: 2 to 60 mesh, more preferably 30 to 60 mesh True density: 1.9 to 2.2 g / cc, more preferably 2.0 to 2.1 g / cc Porosity: 33 to 75%, More preferably 45 to 75% Specific surface area: 700 to 1500 m ² / g, more preferably 900 to 1300 m ² / g Pore volume: 0.5 to 1.4 cc / g, more preferably 0.7 to 1.4 cc / G Average pore size: 1 to 40 °, more preferably 15 to 40 ° When liquid phosgene is treated with activated carbon, the conditions for passing through activated carbon are usually space velocities (SV) = 2 to 10.
Degree, preferably about 2 to 5, more preferably 2 to 4
Process by degree. If the SV value is too large, a small amount of adsorbed chlorine leaks at the outlet of the activated carbon tower, which is not preferable. In addition, the passing liquid temperature is usually 0 to 5 ° C. and about 120 g.
-Adsorption capacity of about chlorine / kg-activated carbon can be maintained.

In order to produce the PC resin of the present invention, it is essential to use a monophenol as a molecular weight regulator (chain terminator) of the PC resin. Monophenols are
With the exception of the number of phenolic hydroxyl groups, those having the same structure as the above-mentioned aromatic diols can be employed, but the amount of the low molecular compound generated in the PC resin may be slightly different depending on the type.

Suitable monophenols include various phenols, for example, normal phenol, pt-
1 carbon atoms such as butylphenol and p-cresol
Included are ~ 10 alkyl phenols, and halogenated phenols such as p-chlorophenol and 2,4,6-tribromophenol. Among them, phenol,
Alkyl phenols such as isopropyl phenol, isooctyl phenol and pt-butyl phenol are preferred. The amount of the monophenol used depends on the molecular weight of the desired condensate, but is usually used in an amount of 0.5 to 10% by weight based on the aromatic diol.

Use time (addition time) of monophenols
The properties as an optical information recording medium may also change, but, for example, when monophenols are added in the presence of a carbonate-forming compound, a large amount of condensates (diphenyl carbonates) of monophenols are formed, which is not preferable. Sometimes. In particular, when the molar ratio of polyhydric phenol to phosgene is reduced, the time period in which phosgene remains is longer than usual, and there is an environment in which a dimer of a terminator (a condensate of monophenols) is easily formed. In addition, when the addition of monophenols is extremely delayed (Japanese Patent Laid-Open No.
2) Not only is it difficult to control the molecular weight, but also the product has a peculiar shoulder on the low molecular weight side of the molecular weight distribution, which increases the amount of adhesion to the mold, causes sagging during molding, and has more adverse effects Not very good. After all, it can be said that the addition of the terminating agent is preferably performed immediately after the consumption of the carbonate-forming compound is completed and before the molecular weight elongation starts.

In the present invention, an arbitrary branching agent can be used as a raw material of the PC resin. The branching agent used is 3
It can be selected from various compounds having one or more functional groups. Suitable branching agents include compounds having three or more phenolic hydroxyl groups, for example, 2,4-bis (4-hydroxyphenylisopropyl) phenol, 2,6-bis (2-hydroxy- 5-methylbenzyl) -4-methylphenol, 2- (4-hydroxyphenyl) -2- (2,4-
Dihydroxyphenyl) propane and 1,4-bis (4,4'-dihydroxytriphenylmethyl) benzene. In addition, compounds having three functional groups, 2,4-dihydroxybenzoic acid, trimesic acid,
Cyanuric chloride may also be used. Among them, those having three or more phenolic hydroxy groups are preferred. The amount of the branching agent varies depending on the desired degree of branching, but is usually 0.05 to 2 with respect to the aromatic diol.
It is used in an amount of mol%.

The PC resin of the present invention is usually prepared by 1) a method of reacting phosgene with an aromatic diol under interfacial polycondensation conditions or solution polymerization conditions, or 2) a method of reacting phosgene with phenol. Can be produced by a method of producing diphenyl carbonate and reacting it with an aromatic diol under melt condensation conditions.
In particular, the method of the above 1), in particular, a method of reacting an aqueous solution of a metal salt of an aromatic diol with phosgene in an emulsified state in the presence of an organic solvent to obtain a carbonate oligomer is typical and preferred. Hereinafter, the above 1) method will be described in detail.

In the above method, the aromatic diol forms an aqueous phase together with water and a water-soluble metal hydroxide. As the metal hydroxide, an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide is usually used. In the aqueous phase, the aromatic diols react with the hydroxide to form a water-soluble metal salt. In this case, the molar ratio of the aromatic diol to the alkali metal hydroxide in the aqueous phase is 1: 1.8 to 1:
3.5 is preferred, and more preferably 1: 2.0 to 1: 3.2. A small amount of a reducing agent such as hydrosulfite may be added to the aqueous phase.

As the organic solvent to be used, at the reaction temperature and the reaction pressure, phosgene and reaction products such as carbonate oligomers and polycarbonates are dissolved, but water is not dissolved (in the sense that a solution is not formed with water). Contains inert organic solvents. Representative inert organic solvents include aliphatic hydrocarbons such as hexane and n-heptane, methylene chloride, chloroform, carbon tetrachloride, dichloroethane, trichloroethane, tetrachloroethane, dichloropropane, and 1,2-dichloroethylene. Chlorinated aliphatic hydrocarbons, aromatic hydrocarbons such as benzene, toluene and xylene, chlorinated aromatic hydrocarbons such as chlorobenzene, o-dichlorobenzene and chlorotoluene, and substituted aromatic hydrocarbons such as nitrobenzene and acetophenone Contains hydrogen. Among them, chlorinated hydrocarbons such as methylene chloride or chlorobenzene are preferably used. These inert organic solvents are
It can be used alone or as a mixture with another solvent.

The preferred amounts of phosgene and aromatic diol are influenced by the reaction conditions, in particular, the reaction temperature and the concentration of the aromatic diol metal salt in the aqueous phase.
It is important to reduce the amount of the low molecular compound produced. That is, the molar ratio of aromatic diols to phosgene is usually 0.70 to 0.96, preferably 0.75 to 0.96.
0.90, more preferably 0.80 to 0.90, and most preferably 0.85 to 0.90. If this ratio is too small, the loss of phosgene increases, and the formation of condensates of the terminating agents is observed, which is not preferable. On the other hand, if it is too large, it is difficult to obtain a PC resin having a reduced amount of the compound of the formula (1), which is the object of the present invention.

The supply of the condensation catalyst can be carried out prior to the contact with phosgene, and is also preferable. of course,
If desired, the supply of the condensation catalyst may take place upon contact with the phosgene. The condensation catalyst can be arbitrarily selected from many condensation polymerization catalysts used in the two-phase interfacial condensation method. Among them, trialkylamine, N-ethylpyrrolidone, N-ethylpiperidine, N-ethylmorpholine, N-isopropylpiperidine and N-isopropylmorpholine are suitable, and triethylamine and N-ethylpiperidine are particularly suitable.

By forming the oligomer with the molar ratio of phosgene and polyhydric phenol as the raw materials being 0.70 to 0.96, the absolute amount of the compound (PBP) of the formula (1) formed in the obtained polycarbonate resin is reduced. The reason for the reduction is considered as follows.

When the ratio of polyphenol to phosgene is decreased, the chloroformate concentration of the oligomer (hereinafter abbreviated as CF value) necessarily increases, and stochastically, the monochloroformate, bishydroxy and bishydroxy When the chloroformate is charged theoretically in an equivalent amount, 25: 2
Since the ratio becomes 5:50 and the chloroformate value is increased from this state, the bischloroformate body generally tends to have a stochastic image generally. However, it was found that the bischloroformate form was hardly increased in practice, and that the increase was mainly due to the increase in the monochloroformate form. Further, this phenomenon is caused by contacting phosgene in an emulsified state with the phosgene in an emulsified state in order to increase the interfacial area between the raw material polyhydric phenol and the solvent as much as possible before the contact with phosgene. It was also found that the content of the formate body increased.

The reason for this is that the reaction for converting one end of the bishydroxyl compound into a chloroformate proceeds more easily than the reaction for converting the hydroxyl group on the other side of the monochloroformate once formed into a chloroformate. It is presumed that the electron-withdrawing action of the added chloro terminal increases the acidity of the hydroxyl group on the opposite side, and as a result, it is less susceptible to phosgene attack. In addition, it can be said that this reaction can be sufficiently accelerated by increasing the emulsification interface area in the raw material stage (because the contact reaction of the polyhydric phenol of the raw material increases).

In this way, a state in which the monochloroformate is increased more than usual is completed. Therefore, when the same amount of the terminator (monophenol) is added, it is natural that the reaction with the monochloroformate is performed. The opportunity increases, while the chance of reaction with the bischloroformate decreases, and consequently the formula (1) compound formed only from the bischloroformate decreases clearly.

As described above, in order to reduce the volatilization of low-molecular compounds in the obtained polycarbonate resin as much as possible, it is preferable to improve the purity of the polycarbonate resin itself as much as possible. Examples of the method include: 1) removing impurities in the raw material as much as shown above, and 2) executing the phosgenation reaction while avoiding by-products as much as possible.

In the latter method, for example, an organic phase and an aqueous phase are emulsified, and an emulsion having an increased interfacial area is brought into contact with phosgene to minimize dissolution of phosgene in a solvent.
In the meantime, an oligomer is obtained in a direction of consuming phosgene.
When a terminator is reacted with this oligomer, although the content of the obtained low-molecular compound does not change, the thermal stability of the compound is different, and as a result, it is manifested as a phenomenon that it is difficult to volatilize when molded at high temperature. It turns out. The reason why the contact condition between the organic phase and the aqueous phase has an effect is considered as follows.

The compound whose both ends are terminated with a terminator is used as a precursor when the terminator is used in the form of phenol and phosgene does not remain at the stage of use. The method of producing this bischloroformate body is dominated by the volatilization phenomenon during high-temperature molding, and the bischloroformate body produced under the above emulsification conditions is thermally stable. While the resulting sublimable compound PBP can be stably present in the melt, the bischloroformate produced under non-emulsifying conditions provides phosgene dissolved in the reaction solvent. (Phosgenolysis reaction) to produce polycarbonate which is basically the same substance but is thermally unstable and easily deteriorated.
Therefore, it is presumed that such a compound in which both terminals are terminated from the bischloroformate cannot be stably present in the polycarbonate melt, and is easily volatilized during high-temperature molding.

Furthermore, the polycarbonate oligomer produced by using phosgene from which impurities such as Cl ₂ have been removed and the polycarbonate oligomer produced by using phosgene while containing a trace amount of impurities also have different thermal stability. The former oligomer appears less volatile than the latter oligomer. That is, in the two-phase interfacial condensation method, after removing and purifying free chlorine, which is a low boiling point impurity in phosgene used, to improve the purity of the raw material used, methylene chloride (organic phase) as another raw material is used. By emulsifying an alkali metal salt of an aromatic diol (aqueous phase) and bringing the emulsion having an increased interfacial area into contact with phosgene, oligomers formed at the interface convert aromatic diols from the aqueous phase. Since the supply of the alkali metal salt is abundant, the reaction consumption of phosgene is accelerated, the chance of dissolving the phosgene in the solvent is drastically reduced, and as a result, the production of the monochloroformate is predominant, and the bischloroformate is formed. The exchange reaction with phosgene hardly occurs, and as a result, a thermally stable oligomer can be obtained.
_{(2) Since it} contains almost no impurities, polymers and oligomers are not partially chlorinated and do not become thermally unstable. I knew it would be stable.

As described above, when the two-phase interfacial condensation method is employed in the present invention, it is particularly preferable that the organic phase and the aqueous phase are brought into contact with each other prior to contact with phosgene to form an emulsion. In order to form an emulsion, a mixer such as a homogenizer, a homomixer, a colloid mill, a flow jet mixer, or an ultrasonic emulsifier, or a mixer such as a static mixer is used in addition to an ordinary stirrer having a stirring blade. It is preferred to use Emulsions usually have a droplet size of 0.01 to 10 μm and have emulsion stability.

The state of emulsification is usually the Weber number or P /
q (additional power value per unit volume). The Weber number is preferably 10,000 or more, more preferably 20,000 or more, and most preferably 35,000.
That is all. Moreover, about 1,000,000 or less is sufficient as the upper limit. Further, P / q is preferably 2
00 kgm / liter or more, more preferably 500
kg / m / liter or more, most preferably 1000 kg
・ M / L or more.

The contact between the emulsion and phosgene is preferably carried out under a weaker mixing condition than the above emulsifying condition in order to suppress the dissolution of phosgene in the organic phase, and the Weber number is less than 10,000, preferably less than 5,000. , More preferably less than 2,000. Further, as P / q, 2
Less than 00 kgm / liter, preferably 100 kgm
m / liter, more preferably less than 50 kg · m / liter. Contact with phosgene can be achieved by introducing phosgene into a tube reactor or a tank reactor. The temperature at the time of contact is usually 80 ° C or lower, preferably 70 ° C or lower, more preferably 10 to 6 ° C.
5 ° C.

Oligomerization proceeds by contact with phosgene. The concentration of the oligomer in the organic phase at the stage of obtaining the oligomer may be within a range in which the obtained oligomer is soluble, and specifically, is about 10 to 40% by weight. In addition, the ratio of the organic phase to the aqueous alkali metal hydroxide solution of the aromatic diol, that is, the aqueous phase, the volume ratio of 0.2 to 0.2 to
It is preferably 1.0. The average molecular weight (Mv) of the oligomer obtained under such condensation conditions is usually 50
About 0 to 10,000, preferably 1600 to 3000
, But is not limited to this molecular weight.

The oligomer thus obtained is converted into a high molecular weight polycarbonate under polycondensation conditions according to a conventional method. In a preferred embodiment, the organic phase in which the oligomer is dissolved is separated from the aqueous phase, and if necessary, the above-mentioned inert organic solvent is added to adjust the concentration of the oligomer. That is, so that the concentration of polycarbonate in the organic phase obtained by polycondensation is 5 to 30% by weight.
The amount of solvent is adjusted. Thereafter, a water phase containing water and an alkali metal hydroxide is newly added, and in order to further prepare polycondensation conditions, preferably, the above-described condensation catalyst is added,
The desired polycondensation is completed according to the two-phase interfacial condensation method. The ratio of the organic phase to the aqueous phase during the polycondensation is preferably about 1: 0.2 to 1: 1 in terms of volume ratio: organic phase: aqueous phase = 1: 0.2 to 1: 1.

After the completion of the polycondensation, a washing treatment is carried out with an alkali such as sodium hydroxide until the remaining chloroformate group becomes 0.1 μeq / g or less. Thereafter, the organic phase is washed until the electrolyte is exhausted, and finally the inert organic solvent is appropriately removed from the organic phase to separate the polycarbonate. The average molecular weight (Mv) of the polycarbonate thus obtained is usually 10,000 to 10
It is about 0000. 12,000 for disk use
About 20,000, more preferably about 1 to 20,000.
It is about 4,000 to 18,000.

In the above reaction, the addition timing of the condensation catalyst and the branching agent is not particularly limited, but is preferably from immediately after the consumption of phosgene is completed to before the molecular weight elongation starts.
In the present application, the average molecular weight (Mv) refers to the concentration of oligomer or polycarbonate (C) of 0.6 g / d.
It is a value calculated from the specific viscosity (η _sp ) measured at a temperature of 20 ° C. using a 1-methylene chloride solution using the following two formulas.

[0056] The _{η sp /C=[η](1+0.28η sp) [η]} = 1.23 × 10 -5 PC resin obtained by Mv ^0.83 above methods, the way of separating it from the reactor, Alternatively, before or during processing, an effective amount of various additives such as a stabilizer, a mold release agent, a flame retardant, an antistatic agent, a filler, a fiber, and an impact strength improver can be added.

The method for producing the PC resin of the present invention is not particularly limited, and can be easily carried out by those skilled in the art by means such as combining the above-mentioned preferred method with a usual method for producing a PC resin. For example, when using phosgene as a raw material, a means for reducing the chlorine in phosgene to a measured value or less, or a means for emulsifying an aqueous phase and an organic phase and then contacting with phosgene when using a two-phase interfacial condensation method are used. Use
Further, it is preferable to use a single method or a combination of means for adding the monophenols between the time immediately after the consumption of phosgene is completed and the time before the molecular weight elongation starts.
Some of the methods for obtaining the PC resin of the present invention, such as the above-mentioned methods, are known as methods for producing a PC resin. PC resin cannot be obtained.

The PC resin of the present invention can be processed into various molded products, for example, films, yarns, plates, etc. by injection molding, extrusion molding, etc., and can be used in various technical fields, for example, in the electric parts or building industries. Also, they are used for lighting equipment materials and optical equipment materials, especially for lamp housings, optical lenses, optical discs and audio discs. Particularly, it is preferably used in the optical field where high-temperature molding is required.

The optical information recording medium is generally formed by combining a portion of a disc substrate made of a polycarbonate resin layer with a transition metal such as Fe or Co formed by vapor deposition or sputtering, or a rare earth such as Tb, Gd, Nd or Dy. In general, the information recording layer has a layer structure using a silicon-based ceramic or the like as an intermediate layer as a protective layer for protecting the recording layer, and finally using an ultraviolet curable resin or the like as an overcoat layer on the surface. . The optical information recording medium thus formed is mainly used as a write-once and rewritable type.

[0060]

The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the present invention unless it exceeds the gist of the invention. Examples 1 to 5 Bisphenol A (hereinafter also referred to as "BPA") 16.3
1 kg / h, sodium hydroxide 5.93 kg / h and water 101.1 kg / h were added to hydrosulfite 0.0
After melting at 35 ° C. in the presence of 18 kg / hr, 25 ° C.
An aqueous phase cooled to 5 ° C. and an organic phase of 68.0 kg / h of methylene chloride cooled to 5 ° C. each had an inner diameter of 6 mm and an outer diameter of 8 mm.
mm stainless steel pipe, mix in the same pipe,
Further, a homomixer (product name: T.K.
K homomic line flow LF-500)
The emulsion was emulsified to prepare an emulsion.

An aqueous solution (aqueous phase) of sodium salt of bisphenol A (hereinafter also referred to as “BPA-Na”) and an emulsion of methylene chloride (organic phase) obtained as described above are separated from a homomixer. The amount of liquefied phosgene shown in Table 1 was supplied from a 6-mm-diameter, 34-m long Teflon-made pipe reactor connected to the 6-mm, 8-mm-diameter pipe and fed from a separately cooled pipe cooled to 0 ° C. And contacted. This liquefied phosgene is placed in a cylindrical container having a diameter of 55 mm and a height of 500 mm, a particle size of about 30 to 60 mesh, a true density of 2.1 g / cc, a porosity of 40%, a specific surface area of 1200 m ² / g, Pore volume: 0.86 cc / g of activated carbon (Yashikol S, manufactured by Ohira Chemical Co., Ltd.) was filled, and the solution was passed through at -5 ° C and SV = 3.
Liquefied phosgene having a chlorine content as shown in Table 1 was reduced at the outlet of the activated carbon tower to a chlorine content as shown in Table 1.

The phosgenation and oligomerization reactions were carried out while the emulsion was flowing through phosgene and the inside of the pipe reactor at a linear speed of 1.7 m / sec for 20 seconds. At this time, the reaction temperature was adjusted so as to be 60 ° C., respectively, and external cooling was performed to 35 ° C. before entering the next oligomerization tank. The oligomerized emulsion obtained from the pipe reactor in this way is further introduced into a reaction tank with a stirrer having an inner volume of 50 liters, and is stirred at 30 ° C. in a nitrogen gas atmosphere to form an aqueous phase. After the unreacted BPA-Na present therein was completely consumed, the aqueous phase and the organic phase were separated by standing to obtain a methylene chloride solution of the oligomer.
In the oligomerization, the catalyst triethylamine 0.005
kg / h and 0.65 kg / h of the molecular weight regulator pt-butylphenol were each introduced into the oligomerization tank. At this time, the concentration of the chloroformate of the oligomer was measured, and the result is shown in Table 1 in normality in methylene chloride.

23 kg of the above methylene chloride solution of the oligomer was charged into a reaction vessel having an internal volume of 70 liters equipped with a Faudler blade, and 10 kg of methylene chloride for dilution was added thereto. An aqueous solution, 6 kg of water, and 2.2 g of triethylamine were added, and the mixture was stirred at 30 ° C. in a nitrogen gas atmosphere, and a polycondensation reaction was performed for 60 minutes to obtain a polycarbonate.

To this reaction solution, 30 kg of methylene chloride and 7 kg of water were added, and after stirring for 20 minutes, the stirring was stopped.
The aqueous and organic phases were separated. 0.1N to the separated organic phase
After adding 20 kg of hydrochloric acid and stirring for 15 minutes to extract triethylamine and a small amount of remaining alkaline component, the stirring was stopped and the aqueous phase and the organic phase were separated. Further, 20 kg of pure water was added to the separated organic phase, and after stirring for 15 minutes, the stirring was stopped, and the aqueous phase and the organic phase were separated. This operation was repeated until no chlorine ions in the extraction wastewater were detected (three times).

The obtained purified polycarbonate solution was pulverized with a kneader and dried to obtain a granular powder (flake). The flakes were kneaded in a 30 mm twin-screw extruder (made by Ikegai Iron and Steel) at a resin temperature of 290 ° C. under a N ₂ atmosphere, and then pelletized (15 kg / hr). At this time, it relates that the incorporation of operational impurities are concerned (H ₂ 0 for use in a human hand and sweat and cooling) and treated while paying sufficient attention.

For the polycarbonate resin obtained in each of the examples, the average molecular weight (Mv) and the molecular weight distribution (Mw /
Mn), color tone, content of low-molecular compound, volatile low-molecular compound during injection molding, injection moldability and molded article properties were measured and evaluated by the following methods, respectively. The results are shown in Table-1. Was.

(1) Molecular weight distribution (Mw / Mn) GPC apparatus (manufactured by Tosoh Corporation, product name HLC-802)
0), and using tetrahydrofuran as an eluent, four kinds of high-speed GPC packing materials (manufactured by Tosoh Corporation, product name TS
K 5000HLX, 4000HLX, 3000HL
X, and 2000 HLX) from a chart obtained by separation using four columns packed and detection based on the difference in refractive index.
Mw and Mn were determined in terms of polystyrene, and Mw / Mn was calculated.

(2) Color Tone (YI) The flakes were plasticized at 280 ° C. using an injection molding machine (manufactured by Nissei Plastics Industry Co., Ltd., product name: FS80S-12ASE), and were then retained in a cylinder for 15 seconds. 3.2m
An m, 60 mm square sample plate was formed. Also, after plasticization,
A sample plate having a residence time in the cylinder of 5 minutes was also formed.

The color tone (YI value) of these sample plates was measured using a color difference meter (product name: SM-4-CH, manufactured by Suga Test Instruments Co., Ltd.). Of the measured values, a small YI value at 15 seconds retention indicates that the color tone during steady molding is good, and the difference between the 15 seconds and 5 minutes retention YI values (ΔY
The fact that I) is small indicates that the thermal stability at high temperatures is good.

(3) Measurement of Decomposition and Volatile Substances 20 g of the obtained polycarbonate pellets were sealed in a glass tube under vacuum (1 mmHg), and only the pellets were sealed in a glass tube.
Heated at 50 ° C. for 20 minutes, the whole amount of only those adhering to the air-cooled glass vapor phase (150 ° C. to 50 ° C.)
Dissolved in tetrahydrofuran (THF).

The solution was measured by liquid chromatography (LC) (conditions: THF / water (1/1), solvent → T
HF changed to 100%, detector: UV 270 nm, measurement model: Shimadzu LC-9A). Compounds developed by liquid chromatography were identified by LC-MS. The oligomer content in the polycarbonate pellets before heating was determined by directly dissolving the pellets and performing LC analysis.

On the other hand, among the identified compounds, PBP, a compound (C-PTBP) represented by the following formula (3), and a compound (PB ) Were compared.

[0073]

Embedded image

[0074]

Embedded image (In the formula, t-Bu represents a tertiary butyl group, -Ph- represents a phenylene group, and O-BPA-O represents a bisphenol A residue.)

(4) Injection Moldability and Substrate Characteristics The pit shift is determined by three substrates for every 1000 shots, the inner and outer peripheral SFP parts according to the optical disk standard (ISO / IEC 13963), and the outer peripheral seventh to ninth bands. Observed under a microscope.

The release unevenness was visually observed using reflected light and transmitted light on 25 substrates for every 1000 shots. In addition, using an automatic birefringence measuring device ADR-130N manufactured by Oak Works,
In-plane birefringence and perpendicular birefringence were measured, and the maximum and minimum values were shown. The mechanical properties of the substrate are based on the optical disc standard (I
The evaluation was made according to SO / IEC 13963), and those satisfied with a sufficient margin were indicated by ○, and those that were barely satisfied were indicated by Δ. The above results are shown in Table 1.

Comparative Example 1 The procedure of Example 5 was repeated, except that the phosgene was not treated with activated carbon. Comparative Example 2 In Example 5, an aqueous phase composed of bisphenol A, sodium hydroxide, and water and an organic phase of methylene chloride were mixed by passing through an orifice having an inner diameter of 2 mm instead of using a homomixer. The same operation as in Example 5 was performed except that the reaction was carried out with phosgene.

Comparative Example 3 The same operation as in Comparative Example 2 was carried out except that pt-butylphenol as a molecular weight regulator was added simultaneously with the addition of phosgene. Comparative Example 4 According to the method of Comparative Example 2, pt-butylphenol as a molecular weight regulator was added at a later stage of the condensation step. That is, 23 kg of the methylene chloride solution of the oligomer was charged into a 70 liter internal volume reactor equipped with a Faudler blade, 10 kg of methylene chloride for dilution was added thereto, and 2.2 kg of a 25% by weight aqueous sodium hydroxide solution and 6 kg of water were further added. , And 2.2 g of triethylamine, and the mixture was stirred at 30 ° C. under a nitrogen gas atmosphere, and subjected to a polycondensation reaction for 15 minutes to give p of a molecular weight regulator.
-T-Butylphenol was added, and stirring was further continued for 15 minutes to obtain a polycarbonate. Otherwise, Comparative Example 2
The same operation as described above was performed.

Comparative Example 5 In Comparative Example 2, 5 kg of a polycarbonate powder obtained by the same method as in Comparative Example 2 except that the molar ratio of phosgene to bisphenol A was changed, was used in a reaction vessel having an internal volume of 70 liters with a Faudler blade. , And stirred at 30 ° C. in a nitrogen gas atmosphere using 20 L of acetone, and washed for 1 hour. The powder and acetone were separated by a 48-mesh wire net and dried. Otherwise, the same operation as in Comparative Example 2 was performed.

Comparative Example 6 In Example 5, phosgene having a high chlorine content was used,
The same operation as in Example 5 was performed except that the activated carbon tower was passed through the liquid at V = 20.

Comparative Example 7 The same operation as in Comparative Example 2 was carried out except that the molar ratio between phosgene and bisphenol A was changed. Various characteristics of these comparative examples were evaluated in the same manner as in Examples 1 to 5, and the results are shown in Table 2.

[0082]

[Table 1]

[0083]

[Table 2]

[0084]

[Table 3]

[0085]

[Table 4]

[0086]

According to the present invention, the PC resin obtained is
In addition to having excellent physical properties unique to C resin, the thermal stability in high-temperature molding is remarkably improved, and low-molecular-weight volatiles are reduced, and a molded product with less coloring can be obtained. This has the advantage that the range of application can be greatly expanded. In particular, when this is used as a substrate of an optical information recording medium, an optical information recording medium having excellent characteristics can be obtained. Further, according to the present invention, by controlling the quantitative ratio of phosgene to aromatic diol as a raw material, such a PC resin can be produced without complicated processing such as acetone extraction.

Continued on the front page (72) Inventor Shigeo Higashi 1-1 Kurosaki Castle Stone, Yahata-nishi-ku, Kitakyushu City F-term in the Kurosaki Plant of Mitsubishi Chemical Corporation (reference) 4J029 AA09 AB01 AB04 AC02 AD01 AE04 BB04A BB05A BB12A BB13A BB16B BD09A BE05A BF14A BH02 DB11 DB13 HA01 HC01 JC031 JC231 JC241 KA03 KB02 KB04 KE11 5D029 KA07

Claims (6)

[Claims] 1. A polycarbonate resin obtained by polymerizing an aromatic diol and a carbonate-forming compound with a monophenol as a molecular weight regulator, wherein the polycarbonate resin is represented by the following general formula (1). The content of the low-molecular compound is 0.1 to 0.35% by weight,
When the polycarbonate resin is heated at 350 ° C. under a vacuum of 1 mmHg for 20 minutes, the proportion of the low-molecular compound volatilized is 0.2% by weight or less of the low-molecular compound contained in the polycarbonate resin. A polycarbonate resin, characterized in that: Embedded image (However, R ¹ represents an aromatic diol residue, and R ² represents a monophenol residue.) 2. An emulsion comprising an organic phase containing an organic solvent and an aqueous phase containing water and a metal salt of an aromatic diol are contacted under emulsifying conditions to form an emulsion. Phosgene is used at a molar ratio of aromatic diols to phosgene of 0.1.
The polycarbonate resin according to claim 1, wherein the polycarbonate resin is produced through a step of obtaining an oligomer by bringing the oligomer into contact at a ratio of 70 to 0.96 and under a condensation reaction condition under a mixing condition weaker than the emulsification condition. Manufacturing method. 3. The phosgene has a chlorine content of 1500 ppb.
The method for producing a polycarbonate resin according to claim 2, wherein: 4. The phosgene has a chlorine content of 1000 ppb.
The method for producing a polycarbonate resin according to claim 3, wherein: 5. A substrate for an optical information recording medium comprising the polycarbonate resin according to claim 1. 6. An optical information recording medium comprising an optical recording layer provided on a substrate made of the polycarbonate resin according to claim 1.