JPH0649195A - Plastic container for food - Google Patents

Abstract

PURPOSE:To obtain a plastic container for food which has improved heat resistance, abrasion resistance, and clarity and can be heated in a microwave oven by using an arom. polycarbonate resin which contains a specified amt. of a specific fluorene deriv. unit and has a specific viscosity in a specified range. CONSTITUTION:The container is made from an arom. polycarbonate resin which comprises structural units of formula I (wherein R1 to R4 are each H, halogen, phneyl, or 1-3C alkyl) in a content of 5-50% and structural units of formula II (wherein W is a single bond, alkylidene, cycloalkylidene, oxide, etc.; R5 and R6 are each H, halogen, phenyl, or 1-3C alkyl ; and m and n are each 1-4) and has a specific viscosity (0.7g/100ml methylene chloride soln., 20 deg.C) of 0.19-0.63. The resin is produced by reacting a 9,9-bis(4-hydroxyphenyl)fluorene compd. which corresponds to the unit of formula I, a dihydric phenol compd. which corresponds to the unit of formula II, a terminal stopper, and a carbonate precursor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a food-grade plastic container, and more particularly to a food-grade plastic made of an aromatic polycarbonate resin which is applicable to a microwave oven and has excellent heat resistance, abrasion resistance and transparency. Regarding the container.

[0002]

2. Description of the Related Art Recently, in order to reduce the weight and the thickness, food containers have been made plastic, and heat-resistant plastic containers applicable to microwave ovens have been required. In addition to the heat resistance applicable to microwave ovens, the heat resistant plastic container is also required to have performance such as abrasion resistance and transparency.

Aromatic polycarbonate resins obtained by reacting bisphenol A with a carbonate precursor are widely used as engineering plastics because of their excellent transparency and heat resistance, and are heat resistant foods applicable to microwave ovens. It is also used as a container. However, there is a demand for an aromatic polycarbonate resin having excellent heat resistance while maintaining its appearance and transparency.

On the other hand, an aromatic polycarbonate resin obtained by reacting 9,9-bis (4-hydroxyphenyl) fluorene with a carbonate precursor is known, and it is also known that it has good heat resistance (special feature). Kaisho 63-18
2336 publication). However, when this homopolymer is synthesized, a large amount of components insoluble in the solvent are produced, and the yield of the solvent-soluble components is at most about 60 to 70%, which is impractical. In addition, there is a problem that even if it is attempted to inject, extrude or compression-mold it, the melt viscosity is too high to be molded.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a food container having improved heat resistance, abrasion resistance and transparency applicable to a microwave oven made of an aromatic polycarbonate resin. Is.

The present inventor has diligently studied a method for producing a practical aromatic polycarbonate resin from 9,9-bis (4-hydroxyphenyl) fluorene without achieving the above object, and as a result, 9,9 -Bis (4
Aromatic polycarbonate resin obtained by copolymerizing -hydroxyphenyl) fluorene in a specific ratio has excellent heat resistance while maintaining excellent appearance and transparency, and has been found to be extremely effective as a container for heat-resistant food, and has reached the present invention. did.

[0007]

The present invention provides the following general formula [1]:

[0008]

[Chemical 3]

[Wherein R _{1 to} R ₄ are a hydrogen atom, a halogen atom, a phenyl group or an alkyl group having 1 to 3 carbon atoms,
It may be the same or different. ] And the following general formula [2]

[0010]

[Chemical 4]

[Wherein W is a single bond, an alkylidene group, a cycloalkylidene group, a phenyl group-substituted alkylidene group, a sulfone group, a sulfide group or an oxide group, and R ₅ and R ₆ are a hydrogen atom, a halogen atom, a phenyl group, It is an alkyl group having 1 to 3 carbon atoms and may be the same or different, and m and n are each an integer of 1 to 4. ] The content of the structural unit represented by the general formula [1] is 5 to 50%, and 0.7 g is 100 ml.
The present invention relates to a plastic container for food made of an aromatic polycarbonate resin having a specific viscosity of 0.19 to 0.63 measured at 20 ° C. in a solution dissolved in methylene chloride.

The polycarbonate resin to be used in the present invention includes 9,9-bis (4-hydroxyphenyl) fluorenes corresponding to the constitutional unit represented by the general formula [1] and represented by the general formula [2]. It is obtained by the reaction of the dihydric phenol corresponding to the constitutional unit, the terminal stopper and the carbonate precursor. It is usually obtained by an interfacial polycondensation method using phosgene or a transesterification reaction using a carbonic acid diester.

Examples of 9,9-bis (4-hydroxyphenyl) fluorenes corresponding to the constitutional unit represented by the general formula [1] include 9,9-bis (4-hydroxyphenyl) fluorene, 9,9. -Bis (3-methyl-4-
Hydroxyphenyl) fluorene, 9,9-bis (3-
Examples include ethyl-4-hydroxyphenyl) fluorene and the like. Among them, 9,9-bis (4-hydroxyphenyl) fluorene is preferable.

Examples of dihydric phenols corresponding to the constitutional unit represented by the general formula [2] include bis (4-hydroxyphenyl) methane, 2,2-bis (4-hydroxyphenyl) propane and 2,2. -Bis (4-hydroxy-3-methylphenyl) propane, 4,4-bis (4-
Hydroxyphenyl) heptane, 2,2-bis (4-hydroxy-3,5-dichlorophenyl) propane, 2,
2-bis (4-hydroxy-3,5-dibromophenyl) propane, bis (4-hydroxyphenyl) oxide, bis (3,5-dichloro-4-hydroxyphenyl) oxide, 4,4'-dihydroxydiphenyl,
3,3'-dichloro-4,4'-dihydroxydiphenyl, bis (4-hydroxyphenyl) sulfone, bis (3,5-dimethyl-4-hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) sulfide, bis ( 4-hydroxyphenyl) sulfoxide and the like can be mentioned. Among them, 2,2-bis (4-hydroxyphenyl)
Propane is preferred.

In the interfacial polycondensation reaction using phosgene,
Usually, 9,9-bis (4-hydroxyphenyl) fluorenes and dihydric phenols are dissolved in an aqueous solution of an acid binder,
React in the presence of a solvent. As the acid binder, for example, hydroxides of alkali metals such as sodium hydroxide and potassium hydroxide are used. As the solvent, for example, a halogenated hydrocarbon such as methylene chloride or chlorobenzene is used. Terminators can be used for molecular weight control, for example monohydric phenols such as p-tert-butylphenol. The amount used is 0.01 to 10 mol%, preferably 0.03 to 8 mol% based on the dihydric phenol.
Is. The reaction is completed at 0 to 40 ° C, preferably 20 to 30 ° C for about 10 minutes to 10 hours. It is preferable to keep the pH of the reaction system at 10 or more as the reaction progresses. A catalyst may be used to accelerate the reaction, and examples of the catalyst include tertiary amines such as triethylamine, tetra-n-butylammonium bromide and tetra-n-butylphosphonium bromide, quaternary ammonium compounds, and quaternary ammonium compounds. Examples thereof include phosphonium compounds. Further, an antioxidant can be added if necessary.

In the transesterification reaction using a carbonic acid diester, an alcohol produced by stirring 9,9-bis (4-hydroxyphenyl) fluorenes and dihydric phenols with a carbonic acid diester under heating in an inert gas atmosphere. Alternatively, it is carried out by distilling phenol. The reaction temperature varies depending on the boiling point of the alcohol or phenol to be produced, but is usually in the range of 120 to 350 ° C. In the latter stage of the reaction, the system is depressurized to facilitate the distillation of the alcohol or phenol produced and complete the reaction. Examples of the carbonic acid diester include diphenyl carbonate, dinaphthyl carbonate, bis (diphenyl) carbonate,
Examples thereof include dimethyl carbonate, diethyl carbonate and dibutyl carbonate. Of these, diphenyl carbonate is preferred.

A polymerization catalyst can be used to accelerate the reaction, and examples of the polymerization catalyst include hydroxides of alkali metals and alkaline earth metals such as sodium hydroxide and potassium hydroxide, and waters of boron and aluminum. Alkali metal salts and alkaline earth metal salts of oxides, quaternary ammonium salts, alkali metal and alkaline earth metal alkoxides, organic acid salts of alkali metals and alkaline earth metals, zinc compounds, boron compounds, Silicon compounds,
Examples include catalysts used in esterification reactions and transesterification reactions of germanium compounds, organotin compounds, lead compounds, antimony compounds, manganese compounds, titanium compounds, zirconium compounds, etc. Or may be used in combination of two or more kinds. The amount of catalyst used is 0.0001 relative to dihydric phenol
~ 1% by weight, and further 0.0005 to 0.5% by weight
Is preferred.

As the copolymerization method, an ordinary copolymerization method such as the simultaneous use of the above-mentioned dihydric phenols or the mixture of separately synthesized oligomers and the polymerization is adopted. The molecular weight of the aromatic polycarbonate resin thus obtained is
Dissolve in methylene chloride to a concentration of 0.7 g / 100 ml and
The specific viscosity measured at 0 ° C. is suitably 0.19 to 0.63, preferably 0.26 to 0.45. This specific viscosity is 0.
When it is less than 19, the molded product becomes brittle, and when it is more than 0.63, the fluidity is poor and defective molding occurs.

The ratio of the structural unit represented by the general formula [1] to the structural unit represented by the general formula [2] in the aromatic polycarbonate resin targeted by the present invention is (5 to 50 mol%). / (95-50 mol%). When the content of the structural unit represented by the general formula [1] is lower than 5 mol%, heat resistance sufficient for use in a microwave oven is not recognized, and when it exceeds 50 mol%, heat resistance is remarkably improved. , Moldability is deteriorated to cause molding failure, and transparency is deteriorated.

The aromatic polycarbonate resin used in the present invention may contain additives such as heat stabilizers, antioxidants, light stabilizers, colorants, antistatic agents, lubricants and release agents, if necessary. May be added.

The aromatic polycarbonate resin obtained as described above has very high heat resistance and excellent transparency and abrasion resistance, and is therefore most suitable for heat-resistant plastic containers for foods.

[0022]

EXAMPLES The present invention will be further described with reference to the following examples. In the examples, parts and% are parts by weight and% by weight. The specific viscosity, glass transition point, total light transmittance and Taber abrasion hardness were measured by the following methods.

Specific viscosity: 0.7 g of the polymer was dissolved in 100 ml of methylene chloride and measured at 20 ° C. Glass transition point: Measured by 910 type DSC manufactured by DuPont. Total light transmittance: Measured by Σ80 manufactured by Nippon Denshoku Co., Ltd. according to ASTM D-1003. Taber abrasion hardness: Based on JASO ^330-85 7.7, the Δ haze before and after rotating 100 times at a load of 500 g / wheel with a wear wheel CS-10 F was measured by Σ80 manufactured by Nippon Denshoku Co., Ltd.

[0024]

Example 1 9,9-bis (4-hydroxyphenyl)
2.52 parts of fluorene, 14.8 parts of 2,2-bis (4-hydroxyphenyl) propane, 23.8 parts of a 48.5% aqueous sodium hydroxide solution and 361 parts of distilled water were charged into a reactor equipped with a stirrer and dissolved. To this, 162 parts of methylene chloride was added, the mixed solution was cooled to 20 ° C., and 10.0 parts of phosgene was blown in for 40 minutes. Next, a solution prepared by dissolving 0.250 parts of p-tert-butylphenol in methylene chloride was added to the reaction solution, 2.4 parts of a 48.5% aqueous sodium hydroxide solution was added, 0.05 parts of triethylamine was further added, and the mixture was stirred for 2 hours. After completion of the reaction, a lower layer methylene chloride solution of polycarbonate was separated from the reaction solution, the solution was washed with an aqueous hydrochloric acid solution and distilled water, and then methylene chloride was removed by evaporation to obtain a polycarbonate powder. The obtained powder had a specific viscosity of 0.437 and a second-order transition point of 170 ° C.

[0025] Tris (nonylphenyl) in this powder
Phosphite 0.03%, Irganox 1076 0.05% and stearic acid monoglyceride 0.2% were added and extruded at a temperature of 280 ° C to pelletize, and then 40 mm.
φ, 1 mm thick test pieces were injection molded. This product had a total light transmittance of 90% and a Δhaze of 37 due to Taber abrasion.

[0026]

Example 2 9,9-bis (4-hydroxyphenyl)
The amount of fluorene used is 7.58 parts and 2,2-bis (4
A polycarbonate powder was obtained in the same manner as in Example 1 except that the amount of -hydroxyphenyl) propane used was 11.5 parts. The powder had a specific viscosity of 0.425 and a second-order transition point of 202 ° C. Example 1 in this powder
When the same additives as in Example 1 were added and molding was performed and evaluated in the same manner as in Example 1, the total light transmittance was 89%, and Δ due to Taber abrasion.
It was a haze 34.

[0027]

Example 3 9,9-bis (4-hydroxyphenyl)
The amount of fluorene used is 10.1 parts and 2,2-bis (4
A polycarbonate powder was obtained in the same manner as in Example 1 except that the amount of -hydroxyphenyl) propane used was 9.9 parts. The powder had a specific viscosity of 0.419 and a second-order transition point of 215 ° C. The powder was added with the same additives as in Example 1 and molded in the same manner as in Example 1. As a result, the total light transmittance was 87% and the haze was 30 due to Taber abrasion.

[0028]

[Comparative Example 1] Bisphenol A polycarbonate powder having a specific viscosity of 0.451 [Panlite manufactured by Teijin Chemicals Ltd.]
L-1250] had a second-order transition point of 150 ° C. The same additives as in Example 1 were added to this powder, and molding and evaluation were carried out in the same manner as in Example 1. As a result, the total light transmittance was 89% and the Δhaze was 42 due to Taber abrasion.

[0029]

Comparative Example 2 9,9-bis (4-hydroxyphenyl)
The amount of fluorene used is 15.2 parts, 2,2-bis (4-
The amount of hydroxyphenyl) propane used is 6.6 parts and
A polycarbonate powder was obtained in the same manner as in Example 1, except that the amount of p-tert-butylphenol used was 0.243 parts. The powder had a specific viscosity of 0.538 and a second-order transition point of 240 ° C. When the same additives as in Example 1 were added to this powder and the mixture was molded and evaluated in the same manner as in Example 1, an undissolved portion remained in the molded piece and the total light transmittance was 6
It was as low as 7%.

[0030]

[Comparative Example 3] The amount of p-tert-butylphenol used was adjusted to 0.
A polycarbonate powder was obtained in the same manner as in Example 1 except that the amount was 081 parts. The specific viscosity of this powder is 0.7
The secondary transition point at 69 was 175 ° C. When the powder was added with the same additives as in Example 1 and molded and evaluated in the same manner as in Example 1, an undissolved portion remained in the molded piece and the total light transmittance was low at 70%.

[0031]

INDUSTRIAL APPLICABILITY The plastic container for food according to the present invention exhibits extremely high heat resistance, and is excellent in abrasion resistance and transparency, and therefore, it is most suitable as a plastic container for a microwave oven which requires high heat resistance. Moreover, since the aromatic polycarbonate resin used in the present invention is excellent in moldability, it can be processed into tableware of various shapes.

Claims (1)

[Claims] 1. The following general formula [1]: [In the formula, R _{1 to} R ₄ are a hydrogen atom, a halogen atom, a phenyl group or an alkyl group having 1 to 3 carbon atoms and may be the same or different. ] And the following general formula [2] [Wherein W is a single bond, an alkylidene group, a cycloalkylidene group, a phenyl group-substituted alkylidene group, a sulfone group, a sulfide group or an oxide group, and R ₅ and R ₆ are a hydrogen atom, a halogen atom, a phenyl group, and a carbon number of 1 ~ 3 alkyl groups, which may be the same or different, and m and n are integers of 1 to 4, respectively. ] The content of the structural unit represented by general formula [1] is 5
.About.50% and 0.7 g of a solution in 100 ml of methylene chloride has a specific viscosity of 0.19 measured at 20.degree.
A plastic container for food made of an aromatic polycarbonate resin having a particle size of about 0.63.