JPH1135672A - Improved production of poly(arylcarbonate) - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to directly obtain the subject colorless polymer having a high mol.wt. in a high yield at a low temperature capable of avoiding side reactions from an easily available inexpensive dialkyl carbonate and an easily available inexpensive bisphenol in the presence of a specific organic tin catalyst. SOLUTION: This method for producing a poly(arylcarbonate) comprises heating a mixture of a bisphenol [preferably 2,2-bis(4-hydroxyphenyl)propane], a dialkylcarbonate (preferably dimethyl carbonate, etc.), and an organic tin catalyst of the formula: (R<1> R<2> SnOAr)2 O [R<1> , R<2> are each a 1-12C alkyl; Ar is a (non)substituted aryl] (preferably 1,3-diphenoxytetrabutyldistannoxane, etc.), at 100-240 deg.C and subsequently polycondensing the obtained oligo(arylcarbonate) in the presence of an organic tin catalyst or an organic titanium catalyst (preferably titanium isopropoxide, etc.), at a temperature of up to 280 deg.C, while gradually lowering the pressure to 0.1 mmHg.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to an improved method for producing poly (aryl carbonate), and more particularly to a method for reacting a dialkyl carbonate with bisphenol using a selected organotin catalyst and an organotitanium catalyst. (Aryl carbonate).

[0002]

BACKGROUND OF THE INVENTION In general, poly (aryl carbonates), especially those derived from bisphenol A, are one of the important engineering thermoplastics useful for various industries and consumers. Usually they are synthesized either by the interfacial phosgenation of bisphenol A or the melt phase reaction of bisphenol A with diphenyl carbonate [D. Freitag et al., Encyclopedia of Polymer Science a.
nd Engineering) Vol. 11, p. 651 (1988
Year)]. This interfacial process uses toxic and dangerous phosgene. Further, it is necessary to use chlorinated hydrocarbons as a solvent and treat solid waste containing chlorine. Further, the product poly (aryl carbonate) has sodium ions and chloride ions remaining which adversely affect the hydrolysis stability of the product. The melt phase process uses diphenyl carbonate, but the process is expensive because the process for making diphenyl carbonate is not very economical. Furthermore, the phenol remaining in the product has a negative effect on the thermal stability of the poly (aryl carbonate).

Heretofore, there has been an example in which the reaction between a bisphenol and a dialkyl carbonate is promoted by using a certain kind of catalyst. For example, Japanese Unexamined Patent Publication No.
According to Nos. 1627 and 2-284918, alkali metal salts such as sodium methoxide and potassium borohydride can be used. However, it is well known that the alkali metal remaining in the poly (aryl carbonate) adversely affects the hydrolytic stability of the product. One of the more commonly used catalysts is an organic derivative of tin. For example, Japanese Patent Application Laid-Open No. Hei 2-251522
Nos. 2,251,524 and 2,251,525 describe the use of di-n-butyltin oxide as a catalyst. However, under the conditions specified,
Only poly (aryl carbonates) having a molecular weight in the range from 300 to 1000 could be obtained. German Patent No. 4,038,768 describes a two-stage process for converting bisphenol A and diethyl carbonate to poly (aryl carbonate) in the presence of tin alcoholate as a catalyst. However, U.S. Pat.
As taught in US Pat. No. 49,856 (1992), tin alcoholates are not desirable catalysts because they develop color during the reaction of phenol with DMC. For this reason, German Patent No. 4,038,768 recommends that the oligomer be washed with ethanol to remove colored impurities. For the same reason, German Patent 4,038,768 avoids the use of a catalyst in the second stage of the polycondensation. Since no catalyst is used, the polycondensation must be carried out at 340 ° C. It is known that the use of such high temperatures during polycondensation results in undesirable gel formation and consequently reduced yield. This is described in German Patent No. 2,736,
No. 062 (1979), German Patent No. 4,038,
This is evident from the fact that a light-colored polycarbonate was obtained using the same catalyst as described in No. 768 (1991). Further, when the polycondensation was carried out at 270 ° C., only a polymer having a low molecular weight (Mw = 12,800) was obtained. The yield was 60%. in this way,
It is clear that the prior art methods each have various disadvantages which are mentioned. Accordingly, there is provided a method for producing high molecular weight poly (aryl carbonate) from bisphenol and dialkyl carbonate,
Developed a method that can produce colorless polymers in high yields (55-95%) without washing and at relatively low temperatures to avoid undesirable side reactions such as degradation and gel formation Is still required.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a compound of formula I

[0005]

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It is an object of the present invention to provide an improved process for preparing poly (aryl carbonates) directly from dialkyl carbonates and bisphenols which is readily available and relatively inexpensive in the presence of the above compounds. However, the reaction of phenols and bisphenols with dialkyl carbonates is thermodynamically disadvantageous [Freitag (D. Frei
tag) et al., International Version of Applied Chemistry English (Angew. Chem. Int. Ed.,
Engl.) 30: 1598 (1991)]. It has now surprisingly been found that the use of the tin compounds of the above formula I for the reaction of bisphenols with dialkyl carbonates produces high molecular weight, colorless poly (aryl carbonates). This reaction is preferably performed in two stages. In the first stage, using a catalyst of formula I
Reaction of bisphenol and dialkyl carbonate in a temperature range of ~ 200 ° C, the degree of oligomerization is 2-6,
An oligo (aryl carbonate) having 40 to 100 mol% of carbonate end groups is obtained. The oligo (aryl carbonate) is then converted in a separate step by itself or in the presence of 2 to 10% by weight (based on oligomers) of diphenyl carbonate, from a catalyst of formula I or a catalyst derived from an organotitanium compound To obtain a poly (aryl carbonate) which has an inherent viscosity of 0.2 to 0.5 dL / g and has no color and contains no gel, at a temperature of less than 280 ° C. and a pressure of less than 0.1 mmHg.

[0007]

DETAILED DESCRIPTION OF THE INVENTION In the compounds of formula I, R ¹ and R ² each represent a C ₁ -C ₁₂ alkyl group, which may be the same or different, and Ar represents a substituted or unsubstituted aryl group.
An example of an organotin compound that is particularly suitable for the present method is 1,3-diphenoxytetrabutyldistanoxane.
e), 1,3-diphenoxytetraethyldistannoxane, 1,3-diphenoxytetramethyldistannoxane, 1,3-di-p-chlorophenoxytetrabutyldistannoxane and 1,3-di-p- Nitrophenoxytetrabutyldistannoxane.

The dialkyl carbonate which can be used in the present invention is of the following formula II.

[0009]

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Here, R ³ represents a C ₁ -C ₁₀ alkyl group. Preferred carbonates in another aspect of the invention are dimethyl carbonate and diethyl carbonate, which are readily available by a phosgene-free process. In yet another embodiment of the present invention, bisphenols that may be suitable for the present invention are of Formula III:

[0011]

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Here, R ⁴ represents H or C ₁ -C ₄ alkyl, and A represents C ₁ -C ₅ alkylene, C ₂ -C ₅ alkylidene, C ₅ -C ₆ cycloalkylene, O or S. Examples of bisphenols that may be suitable for the present invention include: Bis (hydroxyphenyl) alkanes, for example, bis (4-hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane,
2,2-bis (4-hydroxyphenyl) propane,
2,2-bis (4-hydroxyphenyl) butane, 2,
2-bis (4-hydroxyphenyl) octane, bis (4-hydroxyphenyl) phenylmethane, 2,2-
Bis (4-hydroxy-1-methylphenyl) propane, 2,2-bis (4-hydroxy-tert-butylphenyl) propane and 2,2-bis (4-hydroxy-3
-Bromophenyl) propane; bis (hydroxyaryl) cycloalkanes such as 1,1-bis (4-
(Hydroxyphenyl) cyclopentane and 1,1-bis (4-hydroxyphenyl) cyclohexane; dihydroxyaryl ethers such as 4,4′-dihydroxyphenyl ether and 4,4′-dihydroxy-3,3′-dimethyldiphenyl ether; Dihydroxydiaryl sulfoxides, for example, 4,4'-
Dihydroxydiphenylsulfoxide and 4,4'-
Dihydroxy-3,3'-dimethyldiphenylsulfoxide; and dihydroxydiarylsulfones,
For example, 4,4'-dihydroxydiphenylsulfone and 4,4'-dihydroxy-3,3'-dimethyldiphenylsulfone. Of the compounds exemplified here, 2,
2-Bis (4-hydroxyphenyl) propane is particularly preferred.

The organotin compound can be used in a concentration of 10 ^-2 to 10 ^-6 mol per mol of bisphenol A, and the preferred amount is 10 ^-2 to 10 ^-5 mol per mol of bisphenol A. The dialkyl carbonate is preferably used in excess of the stoichiometric amount, preferably in an amount of from 2 to 3 mol per mol of bisphenol used. The reaction temperature in the first stage of the reaction for producing the oligo (aryl carbonate) must be carefully controlled in the range from 180 to 240 ° C. so as to obtain an oligomer having an average degree of oligomerization equal to 2 to 6. The pressure of the reaction during this stage is between 1 and
It can be 10 atmospheres. The temperature during the post-polycondensation of the second stage must not exceed 280 ° C. The pressure is gradually reduced from 1 atm to about 0.5 mmHg and finally reaches a value of 0.01 mmHg during the last stage of the reaction.

In this second step, it has been found that an organotin compound or an organotitanium compound of the formula I can be used. The organic titanium compound can be selected from alkoxides or aryl oxides of titanium. Specific examples are titanium isopropoxide, titanium-n
-Butoxide, titanium ethoxide, titanium phenoxide, titanium (p-chlorophenoxide), titanium (p-
Nitrophenoxide) and titanium (cresyl oxide). This catalyst is generally used in the range of 10 ^-2 to 10 ^-6 mol per mol of oligo (aryl carbonate), and the preferred amount is 10 ^-2 to 10 ^-5 mol per mol of oligo (aryl carbonate).

A major advantage of the present invention is that bisphenol A
And dialkyl carbonate at a temperature lower than 280 ° C., whereby the inherent viscosity becomes 0.2 to
This means that a high molecular weight, colorless, gel-free poly (aryl carbonate) in the range of 0.5 is obtained. This polycarbonate does not contain chlorinated impurities or alkali metals, and has a low hydroxyl content. Therefore, they are expected to show good hydrolytic and thermal stability.

The method for testing the poly (aryl carbonate) produced by the method of the present invention is described below. The results are shown in the examples. 1) The inherent viscosity was measured at 30 ° C. in chloroform using an Ubbelohde viscometer. 2) The degree of oligomerization was estimated in chloroform at 35 ° C. using a gas phase osmometer.

3) The hydroxyl value is determined by the macromolecule (Macro
molecules), Vol. 26, page 1186 (1993), and estimated by UV-visible spectroscopy. 4) The mole% of carbonate end groups in the oligomer is
Measured by ¹ H NMR spectroscopy by integrating the area under the peak at 3.9δ from methoxycarbonate and 4.8δ from hydroxyl end groups.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to embodiments. The following examples are given by way of illustration only and should not be considered as limiting the scope of the invention. Example 1 1,3-Diphenoxytetrabutyldistannoxane (0.34 g) was added to bisphenol A at 150 ° C. under a nitrogen flow.
Dissolved in 11.4 g. Dimethyl carbonate (9 g) was added dropwise to the reaction mixture over 30 minutes. The reaction temperature dropped to 110 ° C. The reaction mixture was refluxed for 8 hours, and a total of 6.6 mL of distillate consisting of by-product methanol and dimethyl carbonate was added within a reaction time of 24 hours.
collected. The reaction temperature gradually rose to 240 ° C. The oligo (aryl carbonate) mixture was washed at room temperature with 1% by weight of cold alkali to remove unreacted bisphenol A. The resulting oligo (aryl carbonate) was a white powder. The yield of the obtained oligo (aryl carbonate) was 8.13 g (69%). The degree of oligomerization of this oligo (aryl carbonate) was 6.4, and the number of carbonate terminal groups was 43 mol%. The molecular weight of the oligo (aryl carbonate) is 1
071 and the hydroxyl number was 8.7.

Example 2 Bisphenol A 22.8 g, dimethyl carbonate 2
A mixture of 0.7 g and 0.67 g of 1,3-diphenoxytetrabutyldistannoxane (molar ratio 1: 2: 0.0
5) was reacted at 150 ° C. Within a reaction time of 24 hours, a total of 16 mL of distillate consisting of by-products methanol and dimethyl carbonate was distilled off. Reaction temperature is 200 ° C
Up. The oligo (aryl carbonate) mixture was washed at room temperature with 1% by weight of cold alkali to remove unreacted bisphenol A. The resulting oligo (aryl carbonate) was a white powder. The yield of the obtained oligo (aryl carbonate) was 15.
5 g (61%), degree of oligomerization 4, and 100 mol% of carbonate end groups. The oligo (aryl carbonate) has a molecular weight of 850 and a hydroxyl value of 8.8.
It was one.

Example 3 A mixture of bisphenol A (22.8 g), dimethyl carbonate (20.7 g) and 1,3-diphenoxytetrabutyldistannoxane (0.67 g) (molar ratio 1: 2: 0.05) ) At 150 ° C. In a reaction time of 16 hours, a total of 13 mL of distillate consisting of by-products methanol and dimethyl carbonate was distilled off. The reaction temperature rose to 156 ° C. The oligo (aryl carbonate) mixture was washed at room temperature with 1% by weight of cold alkali to remove unreacted bisphenol A. The resulting oligo (aryl carbonate) was a white powder. In addition, the obtained oligo (aryl carbonate)
Was 10.2 g (40%), and the degree of oligomerization was 1.
7. The amount of carbonate terminal groups was 82 mol%. The molecular weight of this oligo (aryl carbonate) is 550, OH
The value was 6.4.

Example 4 Oligo (aryl carbonate) having a degree of oligomerization of 6.4 (0.3 g, 2.8 × 10 ^-4 mol) and 1,3-diphenoxytetrabutyldistannoxane (3.74 × 10
^-4 g (2.81 × 10 ⁻⁷ mol) was introduced into a tubular glass reactor (3 cm inside diameter) under a nitrogen atmosphere and heated to 200 ° C. for 30 minutes in a silicone oil bath. The reaction was continued at this temperature under nitrogen for 60 minutes. Thereafter, the reactor was evacuated to 0.1 mmHg and kept at 200 ° C. for 60 minutes. 230 ° C
For 45 minutes, and 30 minutes at 250 ° C and 280 ° C. The obtained polymer was cooled to room temperature, dissolved in chloroform, precipitated with methanol, and dried under vacuum. The polymer yield was 0.2 g (71%) and the inherent viscosity was 0.38 dL / chloroform at 30 ° C.
g, hydroxyl number was 2.1.

Example 5 Oligo (aryl carbonate) having a degree of oligomerization of 3.3 (0.03 g, 4.37 × 10 ^-4 mol) and 1,3-
Diphenoxytetrabutyldistannoxane (5.84 ×
10 ⁻⁴ g, 4.37 × 10 ⁻⁷ mol) were introduced into a tubular glass reactor (3 cm inside diameter) under a nitrogen atmosphere and heated to 200 ° C. for 30 minutes in a silicone oil bath. The reaction was continued at this temperature under nitrogen for 60 minutes. After that, the reactor was
and evacuated to 200 g for 60 minutes. Further 23
The reaction was carried out at 0 ° C for 45 minutes and at 250 ° C and 280 ° C for 30 minutes. Cool the resulting polymer to room temperature,
Dissolved in chloroform, precipitated with methanol and dried in vacuo. The polymer yield was 0.19 g (69%) and the inherent viscosity was 0.39 d in chloroform at 30 ° C.
L / g, hydroxyl number was 2.3.

Example 6 Oligo (aryl carbonate) having a degree of oligomerization of 1.7 (0.3 g, 5.45 × 10 ^-4 mol) and 1,3-diphenoxytetrabutyldistanoxane (7.28 × 1
0 ^-4 g, and 5.45 × 10 ^-7 mol) were introduced into a tubular glass reactor (inner diameter 3 cm) under a nitrogen atmosphere and heated to 30 min 200 ° C. in a silicone oil bath. The reaction was continued at this temperature under nitrogen for 60 minutes. Thereafter, the reactor was cooled to 0.1 mmHg.
And kept at 200 ° C. for 60 minutes. Further 230
The reaction was carried out at 45 ° C for 45 minutes and at 250 ° C and 280 ° C for 30 minutes. The obtained polymer was cooled to room temperature, dissolved in chloroform, precipitated with methanol, and dried under vacuum. The polymer yield was 0.15 g (57%) and the inherent viscosity was 0.23 dL in chloroform at 30 ° C.
/ G, hydroxyl number was 4.2.

Example 7 Oligo (aryl carbonate) having a degree of oligomerization of 6.4 (0.3 g, 2.8 × 10 ⁻⁴ mol) and titanium isopropoxide (7.96 × 10 ⁻⁵ g, 2. (8 × 10 ⁻⁷ mol) was introduced into a tubular glass reactor (3 cm inside diameter) under a nitrogen atmosphere and heated to 200 ° C. for 30 minutes in a silicone oil bath. The reaction was continued at this temperature under nitrogen for 60 minutes.
Thereafter, the reactor was evacuated to 0.1 mmHg and left for 20 minutes for 60 minutes.
It was kept at 0 ° C. 45 minutes at 230 ° C. and 250 minutes
The reaction was carried out at 30 ° C for 30 minutes and at 280 ° C for 45 minutes. The obtained polymer was cooled to room temperature, dissolved in chloroform, precipitated with methanol, and dried under vacuum. Polymer yield 0.21 g (75%), inherent viscosity 30
It was 0.33 dL / g in chloroform at ° C, and the hydroxyl value was 2.3.

Example 8 Oligo (aryl carbonate) having a degree of oligomerization of 6.4 (0.3 g, 2.8 × 10 ^-4 mol), diphenyl carbonate (0.03 g, 1.6 × 10 ^-4 mol) And 1,3-diphenoxytetrabutyldistannoxane (3.74 × 10 ⁻⁴ g, 2.81 × 10 ⁻⁷ mol) were introduced into a tubular glass reactor (3 cm inside diameter) under a nitrogen atmosphere, and silicone oil was added. Heated to 200 ° C. in bath for 30 minutes. The reaction was continued at this temperature under nitrogen for 60 minutes. Thereafter, the reactor was evacuated to 0.1 mmHg and kept at 200 ° C. for 60 minutes. Another 45 minutes at 230 ° C. and 30 minutes at 250 ° C.
For 45 minutes at 280 ° C. The obtained polymer was cooled to room temperature, dissolved in chloroform, precipitated with methanol, and dried under vacuum. The polymer yield is 0.
24 g (94%), inherent viscosity 0.41 dL / g in chloroform at 30 ° C., hydroxyl number 2.2
Met.

Example 9 Oligo (aryl carbonate) having a degree of oligomerization of 6.4 (0.3 g, 2.8 × 10 ^-4 mol), diphenyl carbonate (0.03 g, 1.6 × 10 ^-4 mol) And titanium isopropoxide (7.96 × 10 ⁻⁵ g, 2.8
1 × 10 ⁻⁷ mol) was introduced into a tubular glass reactor (3 cm inside diameter) under a nitrogen atmosphere, and the mixture was placed in a silicone oil bath for 30 minutes 20 minutes.
Heated to 0 ° C. The reaction is carried out at this temperature under nitrogen for 60 minutes.
Lasted a minute. Then the reactor was evacuated to 0.1 mmHg,
It was kept at 200 ° C. for 60 minutes. 45 minutes at 230 ° C,
Then, the reaction was carried out at 250 ° C. for 30 minutes and at 280 ° C. for 45 minutes. The obtained polymer was cooled to room temperature, dissolved in chloroform, precipitated with methanol, and dried under vacuum.
The polymer yield was 0.22 g (88%), the inherent viscosity was 0.37 dL / g in chloroform at 30 ° C., and the hydroxyl number was 2.2.

Claims (10)

[Claims] 1. A process for producing a poly (aryl carbonate), comprising a bisphenol, a dialkyl carbonate and a compound of the formula (R ¹ R ² SnOAr) ₂ O, wherein R ¹ and R ² are each C _1-12 alkyl. And Ar is unsubstituted or substituted aryl]
Is heated to a temperature in the range of 100-240 ° C. to give the oligo (aryl carbonate), and the pressure is reduced to 280 mm in the presence of an organotin catalyst or an organotitanium catalyst while gradually reducing the pressure to about 0.1 mmHg. A process comprising polycondensing said oligo (aryl carbonate) at a temperature up to ° C. 2. The dialkyl carbonate is dimethyl carbonate, diethyl carbonate, di-n-butyl carbonate, di-tert-butyl carbonate, diamyl carbonate, diheptyl carbonate, dihexyl carbonate or dicyclopropyl carbonate. The described method. 3. The process according to claim 2, wherein the molar proportion of the dialkyl carbonate is at least twice the molar proportion of the bisphenol. 4. The method according to claim 1, wherein the polycondensation catalyst is an alkoxide or aryl oxide of titanium. 5. The method according to claim 1, wherein the polycondensation is carried out in the presence of diphenyl carbonate. 6. A catalyst for preparing an oligo (aryl carbonate), which comprises 1,3-diphenoxytetrabutyldistannoxane, 1,3-diphenoxytetraethyldistannoxane, 1,3-diphenoxytetramethyldistannoxane. 2. The distannoxane selected from the group consisting of 1,3-di-p-chlorophenoxytetrabutyldistannoxane and 1,3-di-p-nitrophenoxytetrabutyldistannoxane. Method. 7. The method according to claim 1, wherein the final temperature during the preparation of the oligo (aryl carbonate) ranges from 180 to 240 ° C. 8. An oligo (aryl carbonate) comprising:
The method of claim 1 wherein the polycondensation is carried out by post-polycondensation at a temperature in the range of 00 to 280 ° C, a pressure in the range of 760 to 0.1 mmHg and a reaction time of 3 to 5 hours. 9. The method according to claim 1, wherein the hydroxyl number of the poly (aryl carbonate) is 2-4. 10. An improved method for producing poly (aryl carbonate), comprising a compound of formula III Wherein A is isopropylidene, methylene, hexafluoroisopropylidene, ethylmethylene, isobutylmethylmethylene, diphenylmethylene, phenylmethylmethylene, phthaline, phthalimide, N-substituted phthalimide (phenyl, methyl), dihydroanthracene, Indane, spirobisindane, thiophene,
Represents azo, dimethyldiphenylsilane, tetraphenylsilane, hydroquinoids, cyclohexane, sulfide, sulfone, sulfoxide, ketone, ester or amide, wherein R ⁴ is methyl, ethyl,
A phenol of the formula I Wherein R ¹ and R ² each represent a C ₁ -C ₁₂ alkyl group which may be the same or different, and Ar represents a substituted or unsubstituted aryl group.
C. and heated to the formula II Wherein R ³ represents a C ₁ -C ₁₀ alkyl group, to the reaction mixture;
Heating to a temperature in the range of ２５０ to 250 ° C. and converting the resulting alcohol as an azeotrope with the dialkyl carbonate to 8 to 2
Distill slowly for 4 hours to obtain a degree of oligomerization of 2
6, a compound having a carbonate terminal group of 40 to 100 mol%
IV The unreacted dialkyl carbonate is distilled by raising the temperature further to 200-260 ° C. and, if necessary, the oligo (aryl carbonate) is added at room temperature so as to be free of unreacted phenol. The oligo (aryl carbonate) is post-polycondensed at a temperature not exceeding 280 ° C., and 10 ⁻² per mol of the oligo (aryl carbonate).
In the presence of an organotin catalyst or an organotitanium catalyst in the range of 10 ^-6 mol, the temperature is slowly increased stepwise while reducing the pressure from 760 mmHg to 0.1 mmHg over a period of 3 to 5 hours. A poly (aryl carbonate) of the formula (I).