JP2004292730A - Aromatic polycarbonate for blow molding, and method for producing blow molded article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a polycarbonate for blow molding that has excellent mechanical properties and transparency that the polycarbonate originally retains and which gives a blow molded article having uniform wall thickness and good appearance, e.g., surface gloss, and provide a method for producing the blow molded article using the same. <P>SOLUTION: The aromatic polycarbonate for blow molding has a viscosity average molecular weight of 24,000-30,000, a draw down value (DD) of 0.250-0.450 and a melt tension (MT) satisfying the following formulas (1) and (2): 150mN≤MT≤60 mN (1) and MT>250-500×DD(mN) (2). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【００４７】
【発明の効果】
本発明のブロー成形用芳香族ポリカーボネートはブロー成形性に優れ、ブロー成形品は、衝撃強度等の機械的特性、耐熱性、透明性、外観に優れているので、乳製品ボトル、清涼飲料水ボトル、水ボトル、その他の食品用容器として使用できる。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an aromatic polycarbonate for blow molding and a method for producing a molded product obtained by blow molding the polycarbonate. Specifically, aromatic polycarbonate for blow molding having specific drawdown properties, melting properties such as melt tension, and excellent in hue and appearance of a molded article, and impact strength, and a method for producing a blow molded article using the polycarbonate About.
[0002]
[Prior art]
Aromatic polycarbonate is used in many fields, including hollow containers for drinking water, as a resin having excellent heat resistance, mechanical properties, dimensional stability, transparency, and the like.
Aromatic polycarbonates used for general applications have a linear molecular structure.Aromatic polycarbonates having such a molecular structure are more suitable for drawdown and meltdown during melt molding than ABS resins and the like. The die swell is large, and the thickness distribution of the blow molded product is likely to be non-uniform, so that improvement has been desired. As a method for improving the melting characteristics such as drawdown property of an aromatic polycarbonate, a method of branching polycarbonate using a branching agent is known. That is, in the so-called interfacial polymerization method, 1,1,1- as a branching agent together with 2,2-bis (4-hydroxydiphenyl) propane (hereinafter abbreviated as “bisphenol A” or “BPA”). There is known a method of branching an aromatic polycarbonate using a polyfunctional compound such as tris (4-hydroxylphenyl) ethane (THPE) and 1,3,5-tris (4-hydroxyphenyl) benzene ( For example, Patent Documents 1 and 2). In addition, when an aromatic polycarbonate is produced by transesterification of an aromatic dihydroxy compound and a carbonic acid diester by a so-called melting method, a method of branching the polycarbonate using a polyfunctional compound has also been proposed (for example, , Patent Document 3).
[0003]
However, in order to stably mold a hollow container having a good surface appearance and a uniform thickness, not only the drawdown property of the resin but also the melt tension and the like are involved. Therefore, by the method using the above-described branching agent, even if a resin in which the parison of the molten resin is difficult to draw down during blow molding is obtained, a hollow container having a good surface appearance and a uniform thickness can be stably formed. It was difficult to manufacture. Further, when a polyfunctional compound is used, there is a problem that the reactivity is poor or the obtained polycarbonate is colored depending on the kind and the amount of the polyfunctional compound used.
It has been reported that a branched structure is also present in an aromatic polycarbonate produced by a transesterification method without using a branching agent (Non-Patent Documents 1 and 2).
[0004]
[Patent Document 1]
JP-B-44-17149 [Patent Document 2]
JP-A-2-55725 [Patent Document 3]
Japanese Patent Application Laid-Open No. 4-89824 [Non-Patent Document 1]
Polymer, 42 (2001), P7653
[Non-patent document 2]
Encyclopedia of Polymere Science and Technology, vol. 10 (1969), P723
[0005]
[Problems to be solved by the invention]
An object of the present invention is to provide a polycarbonate having the original mechanical properties and transparency of an aromatic polycarbonate, a uniform product thickness, and a blow molded product having a good appearance such as surface gloss and the like, and blow molding using the same. To provide a method for producing a molded article.
[0006]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to solve the above problems, and as a result, although the theoretical basis is not clear, an aromatic polycarbonate produced by a transesterification method has drawdown and melt properties suitable for blow molding. In some cases, a blow-molded article having an excellent appearance can be obtained, and it has been found that such a polycarbonate has a specific drawdown property and a melt tension measured by a method described later, and to complete the present invention. Reached. That is, the gist of the present invention is that the viscosity average molecular weight is 24,000 to 30,000, the drawdown property (DD) defined in this specification is 0.250 to 0.450, and the melt tension (MT) ) Satisfies the following formulas (1) and (2).
[0007]
[Equation 3]
150mN ≦ MT ≦ 60mN (1)
[0008]
(Equation 4)
MT> 250-500 × DD (mN) (2)
[0009]
The present invention also resides in a method for producing a blow molded article using such a polycarbonate. In this specification, the drawdown property (DD) and the melt tension (MT) mean physical properties measured by the methods described in Examples described later.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described specifically.
The aromatic polycarbonate according to the present invention is obtained by the reaction of an aromatic hydroxy compound and a carbonate precursor, and as long as it has the molecular weight and melting characteristics defined in the present invention, its production method is not limited, Particularly, it can be produced by polymerizing an aromatic dihydroxy compound and a carbonic acid diester by a transesterification reaction according to the following method.
[0011]
Aromatic dihydroxy compound : Representative examples of the aromatic dihydroxy compound which is one of the raw materials of polycarbonate include bis (4-hydroxydiphenyl) methane, 2,2-bis (4-hydroxyphenyl) propane, , 2-bis (4-hydroxy-3-methylphenyl) propane, 2,2-bis (4-hydroxy-3-t-butylphenyl) propane, 2,2-bis (4-hydroxy-3,5-dimethyl) Phenyl) propane, 2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, 4,4-bis (4-hydroxyphenyl) heptane, 1,1-bis (4-hydroxyphenyl) cyclohexane, , 4'-dihydroxybiphenyl, 3,3 ', 5,5'-tetramethyl-4,4'-dihydroxybiphenyl, bis (4- (Hydroxyphenyl) sulfone, bis (4-hydroxyphenyl) sulfide, bis (4-hydroxyphenyl) ether, bis (4-hydroxyphenyl) ketone, and the like. These aromatic dihydroxy compounds can be used alone or in combination of two or more. Furthermore, polyhydric phenols having three or more hydroxy groups in the molecule, such as 1,1,1-tris (4-hydroxyphenyl) ethane (THPE) and 1,3,5-tris (4-hydroxyphenyl) benzene And the like can be used in combination in a small amount as a branching agent, but it is preferable not to use a branching agent. Among these aromatic dihydroxy compounds, 2,2-bis (4-hydroxyphenyl) propane (hereinafter, also referred to as “bisphenol A” and sometimes abbreviated as “BPA”) is particularly preferable.
[0012]
Carbonic acid diester : Representative examples of the carbonic acid diester as another raw material include, for example, substituted diphenyl carbonate represented by diphenyl carbonate, ditolyl carbonate, etc., dimethyl carbonate, diethyl carbonate, di-t-butyl carbonate And the like. These carbonate diesters can be used alone or in combination of two or more. Of these, diphenyl carbonate (hereinafter sometimes abbreviated as "DPC") and substituted diphenyl carbonate are preferred.
[0013]
The above-mentioned carbonic acid diester may be substituted with a dicarboxylic acid or a dicarboxylic acid ester in an amount of preferably 50 mol% or less, more preferably 30 mol% or less. Representative dicarboxylic acids or dicarboxylic esters include terephthalic acid, isophthalic acid, diphenyl terephthalate, diphenyl isophthalate, and the like. When substituted by such a dicarboxylic acid or dicarboxylic acid ester, a polyester carbonate is obtained.
[0014]
These carbonic acid diesters (including the substituted dicarboxylic acids or dicarboxylic acid esters described above; the same applies hereinafter) are usually used in excess with respect to the aromatic dihydroxy compound. That is, it is used in a molar ratio of 1.001 to 1.3, preferably 1.01 to 1.2 with respect to the aromatic dihydroxy compound. When the molar ratio is less than 1.001, the terminal OH groups of the produced aromatic polycarbonate increase, and the heat stability and hydrolysis resistance are deteriorated. Although the terminal OH group of the aromatic polycarbonate decreases, the transesterification rate decreases under the same conditions, and it tends to be difficult to produce an aromatic polycarbonate having a desired molecular weight. In the present invention, it is preferable to use an aromatic polycarbonate having a terminal OH group content adjusted within the range of 50 to 2,000 ppm, preferably 100 to 1,500 ppm, and more preferably 300 to 1,000 ppm.
[0015]
As a method of supplying the raw material to the raw material mixing tank, it is easier to maintain high measurement accuracy in the liquid state, so that one or both of the aromatic dihydroxy compound and the carbonic acid diester are melted and supplied in the liquid state. Is preferred. When the raw material is supplied in a liquid state, an oval flow meter, a micro motion type flow meter, or the like can be used as the measuring device. On the other hand, when the raw material is supplied in a solid state, it is preferable to use a device that measures the weight, rather than a device that measures the volume such as a screw feeder, and a weight feeder such as a belt type or a loss-in-weight type. Can be used, but the loss-in-weight method is particularly preferable.
[0016]
Transesterification catalyst : When an aromatic polycarbonate is produced by a transesterification method, a catalyst is used. There is no limitation on the type of catalyst used for the production of the aromatic polycarbonate, but generally, a base such as an alkali metal compound, an alkaline earth metal compound, a basic boron compound, a basic phosphorus compound, a basic ammonium compound or an amine compound is used. An acidic compound is used, and among them, an alkali metal compound and / or an alkaline earth metal compound are particularly preferable. These may be used alone or in combination of two or more.
[0017]
Examples of the alkali metal compound include inorganic alkali metal compounds such as lithium, sodium, potassium, rubidium, and cesium hydroxides, carbonates, and hydrogencarbonate compounds, and organic alkali metal compounds such as alcoholates, phenolates, and organic carboxylate salts. Can be Among these alkali metal compounds, cesium compounds are preferable, and cesium carbonate, cesium hydrogencarbonate, and cesium hydroxide are specifically the most preferable cesium compounds.
[0018]
Examples of the alkaline earth metal compound include inorganic alkaline earth metal compounds such as beryllium, magnesium, calcium, strontium, barium hydroxide and carbonate, and organic alkaline earth metal compounds such as alcoholate, phenolate, and organic carboxylate. Is mentioned.
[0019]
Among these catalysts, alkali metal compounds are desirable for obtaining an aromatic polycarbonate having melting properties suitable for blow molding. In the present invention, the transesterification catalyst is used in the form of a catalyst solution dissolved in a solvent. Examples of the solvent include, in addition to water, acetone, alcohol, toluene, and phenol, a solvent that dissolves a raw material aromatic dihydroxy compound, carbonic acid diester, and the like. Among these solvents, water is preferable, and when an alkali metal compound is used as a catalyst, an aqueous solution is preferable.
The amount of the catalyst used is 4 × 10 ⁻⁷ to 1 × 10 ⁻⁵ mol, preferably 1 × 10 ^{−6 to} 6 × 10 ⁵ mol of the alkali metal per mol of the aromatic dihydroxy compound in the case of the alkali metal catalyst. It is used within a range of ^-6 mol. If the amount of the catalyst used is less than the above amount, it is difficult to obtain an aromatic polycarbonate having the polymerization activity and melting properties required for producing an aromatic polycarbonate having a desired molecular weight, and the residence time during polymerization may be increased, or the temperature may be increased. Must be increased, and as a result, the hue of the obtained polycarbonate deteriorates. Conversely, if the amount of the catalyst is too large, the hue and the hydrolysis resistance are deteriorated, the amount of the branched structure is too large, the fluidity is reduced, the desired melting property cannot be obtained, and the amount of foreign substances due to the generation of the gel is also reduced. There is a fear that it may increase, and also lead to a decrease in impact strength and transparency.
[0020]
Production method of aromatic polycarbonate: The transesterification reaction of aromatic polycarbonate is not particularly limited as long as it can be polymerized by ordinary transesterification polycarbonate production equipment, but the type of catalyst, amount of catalyst, monomer charge ratio, polymerization temperature, residence time These values change variously depending on polymerization conditions such as the degree of pressure reduction and the degree of pressure reduction. For example, in the present invention, the polymerization reaction (ester exchange reaction) of the aromatic polycarbonate is generally carried out continuously in two or more polymerization tanks, that is, in two or more stages, usually three to seven stages. Preferably. Specific reaction conditions are as follows: temperature: 150 to 320 ° C., pressure: normal pressure to 2 Pa, average residence time: 5 to 150 minutes, and in each polymerization tank, discharge of phenol by-produced as the reaction proceeds. Are set stepwise at a higher temperature and a higher vacuum within the above reaction conditions in order to make more effective.
In the case where a plurality of polymerization tanks are used in the multi-stage process, it is preferable to automatically control the actual amount of the catalyst continuously and continuously, and in that case, 1/1/1 of the residence time of the first polymerization tank. It is necessary that the measurement and control be completed within three.
[0021]
The apparatus used in the transesterification reaction may be any of a vertical type, a tube type or a tower type, and a horizontal type. Normally, turbine blades, paddle blades, anchor blades, full zone blades (manufactured by Shinko Pantech Co., Ltd.), Sun Meller blades (manufactured by Mitsubishi Heavy Industries, Ltd.), Max Blend blades (manufactured by Sumitomo Heavy Industries, Ltd.), helical ribbons Following one or more vertical polymerization tanks equipped with wings, twisted lattice blades (manufactured by Hitachi, Ltd.), etc., horizontal uniaxial polymerization tanks such as disk type and cage type, HVR, SCR, N-SCR (Mitsubishi) Heavy Industry Co., Ltd.), Baivolak (Sumitomo Heavy Industries, Ltd.), Glasses Wing, Lattice Wing (Hitachi, Ltd.), or Glasses Wing and Polymer Feeding Function, such as Twisting and Twisting And / or a combination of wings and / or the like with inclination, etc., can be used.
[0022]
In the aromatic polycarbonate produced by the above method, there is usually no chlorine element, and low molecular weight compounds such as a raw material monomer, a catalyst, an aromatic monohydroxy compound and a polycarbonate oligomer by-produced by a transesterification reaction remain. Among them, the raw material monomer and the aromatic monohydroxy compound have a large residual amount, and adversely affect the quality such as heat aging resistance, hydrolysis resistance, odor during molding, odor and taste transfer to the contents, It is preferably removed during commercialization. The residual amount of the aromatic monohydroxy compound is preferably at most 200 ppm by weight, more preferably at most 100 ppm by weight. The residual amount of the aromatic dihydroxy compound is preferably 100 ppm by weight or less, more preferably 50 ppm by weight or less. The residual amount of the carbonic acid diester compound is preferably 200 ppm by weight or less. If the residual amount of the carbonic acid diester compound exceeds 200 ppm by weight, an unpleasant odor is felt, which is not preferable as a blow molding resin.
[0023]
The method for removing various low molecular weight compounds in the aromatic polycarbonate is not particularly limited, and may be, for example, continuously devolatilized by a vent-type extruder. At that time, the basic transesterification catalyst remaining in the resin, by adding an acidic compound or a precursor thereof in advance and deactivating it, suppresses side reactions during devolatilization, efficiently starting monomer and Aromatic hydroxy compounds can be removed.
[0024]
The acidic compound or its precursor to be added is not particularly limited, and any compound can be used as long as it has an effect of neutralizing the basic transesterification catalyst used in the polycondensation reaction. Specifically, hydrochloric acid, nitric acid, boric acid, sulfuric acid, sulfurous acid, phosphoric acid, phosphorous acid, hypophosphorous acid, polyphosphoric acid, adipic acid, ascorbic acid, aspartic acid, azelaic acid, adenosine phosphate, benzoic acid, Formic acid, valeric acid, citric acid, glycolic acid, glutamic acid, glutaric acid, cinnamic acid, succinic acid, acetic acid, tartaric acid, oxalic acid, p-toluenesulfinic acid, p-toluenesulfonic acid, naphthalenesulfonic acid, nicotinic acid, picrin Examples include Bronsted acids such as acids, picolinic acid, phthalic acid, terephthalic acid, propionic acid, benzenesulfinic acid, benzenesulfonic acid, malonic acid, and maleic acid, and esters thereof. These may be used alone or in combination of two or more. Among these acidic compounds or precursors thereof, sulfonic acid compounds or ester compounds thereof, for example, p-toluenesulfonic acid, methyl p-toluenesulfonate, butyl p-toluenesulfonate and the like are particularly preferred.
[0025]
The amount of these acidic compounds or precursors added is 0.1 to 50 times mol, preferably 0.5 to 30 times mol, based on the neutralization amount of the basic transesterification catalyst used in the polycondensation reaction. Add in the range. The timing of adding the acidic compound or its precursor may be any time after the polycondensation reaction, and there is no particular limitation on the addition method, depending on the properties and desired conditions of the acidic compound or its precursor. Any method such as a direct addition method, a method of dissolving in a suitable solvent and adding, a method of using a pellet or flake-like master batch, and the like may be used.
[0026]
The extruder used for devolatilization may be single-screw or twin-screw. The twin-screw extruder is a meshing twin-screw extruder, and the rotation direction may be the same direction rotation or different direction rotation. For the purpose of devolatilization, those having a vent portion after the acidic compound addition portion are preferable. Although the number of vents is not limited, a multistage vent of 2 to 10 stages is usually used. In the extruder, if necessary, additives such as a stabilizer, an ultraviolet absorber, a release agent, and a coloring agent may be added and kneaded with the resin.
[0027]
The aromatic polycarbonate for blow molding of the present invention has a viscosity average molecular weight (Mv) of 24,000 to 30,000. When the viscosity average molecular weight is more than 30,000, the fluidity is reduced, and it becomes difficult to form a thin blow molded product or a large blow molded product. On the other hand, if the viscosity average molecular weight is less than 24,000, the drawdown during blow molding tends to be large, and the impact strength is undesirably reduced. The viscosity average molecular weight can be determined from the solution viscosity measured at 20 ° C. using a methylene chloride solvent as described later.
Further, the aromatic polycarbonate for blow molding of the present invention needs to have a drawdown property (DD) measured by a method described later in the range of 0.250 to 0.450. The drawdown property is preferably from 0.260 to 0.400, and more preferably from 0.270 to 0.380. If the drawdown property is greater than 0.450, the sagging of the parison becomes too large, and the blow molded product is likely to have uneven thickness. On the other hand, when the drawdown property (DD) is less than 0.250, the fluidity is reduced, and it becomes difficult to form a thin blow molded product or a large blow molded product.
The polycarbonate for blow molding of the present invention needs to have a melt tension (MT) satisfying the conditions of the following formulas (1) and (2).
[0028]
(Equation 5)
150mN ≦ MT ≦ 60mN (1)
[0029]
(Equation 6)
MT> 250-500 × DD (mN) (2)
[0030]
The melt tension (MT) is preferably from 140 to 80 mN, more preferably from 130 to 90 mN. If the MT is larger than 150 mN, the melt viscosity tends to be too high, and the die swell tends to be too large, so that the moldability decreases. Conversely, if the melt tension (MT) is smaller than 60 mN or smaller than the lower limit of the formula (2), the thickness of the blow-molded product becomes uneven, which is not preferable.
[0031]
The aromatic polycarbonate for blow molding of the present invention is preferably one produced by a transesterification reaction from a carbonic acid diester compound and an aromatic dihydroxy compound, but the polycarbonate produced by the transesterification method has a drawdown property (DD) adjusted. By doing so, the above formulas (1) and (2) are easily satisfied, and the appearance of the blow molded product is also excellent.
The aromatic polycarbonate produced by the transesterification method is considered to generate a plurality of branched structures during the polymerization reaction, judging comprehensively from the descriptions of Non-Patent Documents 1 and 2. If a plurality of branched structures are present in the same reaction system, the lengths of the branched chains and the like of the respective branched structures are different. It is possible to provide melting characteristics that are difficult to achieve with only the branched structure of the above. Therefore, it is possible to control the balance between the drawdown property and the melt tension, which cannot be realized with a branched polycarbonate comprising only one kind of branching agent, which has been performed by the conventional interfacial polymerization method. It is considered that an aromatic polycarbonate having excellent blow moldability can be easily obtained.
[0032]
The aromatic polycarbonate of the present invention further includes other thermoplastic resins, heat stabilizers, antioxidants, ultraviolet absorbers, release agents, coloring agents, flame retardants, and impact resistance, as long as the objects of the present invention are not impaired. Add desired additives such as a property improver, antistatic agent, slip agent, antiblocking agent, lubricant, antifogging agent, natural oil, synthetic oil, wax, organic filler, inorganic filler, etc. Can be obtained.
[0033]
A hollow container can be produced by using the aromatic polycarbonate for blow molding of the present invention and applying a generally known blow molding method such as direct blow, injection blow, or injection stretch blow. For example, in the case of direct blow molding, the aromatic polycarbonate pellets are supplied to a single-screw or twin-screw extruder having a cylinder set temperature of 240 to 280 ° C, melted and kneaded under screw shearing, and melted in a tube shape through a nozzle. The parison is extruded, then sandwiched in a mold having a predetermined shape and set at 70 to 110 ° C., and blown with air or an inert gas to form a hollow container.
The aromatic polycarbonate for blow molding of the present invention can be subjected to biaxial stretch blow molding disclosed in JP-A-6-122145 and the like. Further, polyethylene terephthalate and the like for improving the gas barrier properties of the aromatic polycarbonate, It can also be used for multilayer blow molding with polyamide.
[0034]
The size of the blow-molded article produced by the present invention is not particularly limited, but the thickness is preferably 0.1 to 7 mm, more preferably 0.2 to 5 mm, from the viewpoint of strength and shape retention of the hollow container. , And most preferably 0.3 to 3 mm.
The blow-molded article produced by the method of the present invention can be used for a wide variety of applications, but is excellent in mechanical properties such as impact strength, heat resistance, transparency, and appearance. It is suitable as a water bottle, a water bottle, and other food containers.
[0035]
【Example】
Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples unless it exceeds the gist. In addition, the analysis and physical property evaluation of the obtained aromatic polycarbonate and the blow molded product were performed by the following methods.
[0036]
(I) viscosity average molecular weight (Mv);
The polycarbonate pellets dried at 120 ° C. for 4 hours are dissolved in methylene chloride, and calculated by the following formula using the intrinsic viscosity [η] obtained from the solution viscosity measured at 20 ° C.
[0037]
(Equation 7)
[Η] = 1.23 × 10 ⁻⁴ Mv ^0.83
[0038]
(Ii) drawdown properties (DD);
The polycarbonate pellets dried at 120 ° C. for 4 hours were extruded at a temperature of 280 ° C., an extrusion speed of 10 mm / min, a diameter of 2 mm, and a length of 5 mm using Capillograph 1C manufactured by Toyo Seiki Co., Ltd. with the heat-retaining chamber open. After passing through the capillary, when the hanging strand becomes 350 mm or more, the strand is cut. After sufficiently cooling the strands, the strands are cut by a length of 50 mm from the larger strand diameter (strand length = 0 mm), and the strand weight is measured for each strand length of 50 mm. The weight is calculated from the following equation, with W2 being six times the weight of the strand having a strand length of 0 to 50 mm and W1 being the total weight of the strand having a strand length of 0 to 300 mm.
[0039]
(Equation 8)
DD = [(W2-W1) / W2]
[0040]
(Iii) melt tension (MT);
The polycarbonate dried at 120 ° C. for 4 hours was heated at 250 ° C. at an extrusion rate of 10 mm using a capillary having a diameter of 1 mm and a length of 10 mm, using Capillograph 1C manufactured by Toyo Seiki Co., Ltd. with the heat retaining chamber open. / Min, take-up speed = 20 m / min, and the distance from the capillary outlet to the tension pulley directly connected to the load cell is measured under the conditions of 400 mm.
[0041]
(Iv) bottle molding and evaluation;
A 5-gallon bottle was blow-molded at 270 to 260 ° C. barrel temperature and 70 ° C. mold temperature with B-30 manufactured by Japan Steel Works, Ltd. The moldability was evaluated by ○ (good) and × (poor) from the torque of the extruder and the appearance of the parison.
[0042]
(V) surface appearance of the molded article;
The 5 gallon bottle molded in the above (iv) was visually observed, and evaluated from シ (good appearance) and × (poor appearance) from the degree of wrinkles and surface gloss.
[0043]
(Vi) thickness distribution;
The bottle was cut into slices at half the height of the 5-gallon bottle formed in the above (iv), the thickness distribution was measured, and the maximum value of the thickness difference was obtained.
[0044]
Examples 1 and 2 and Comparative Examples 1 and 2
A cesium carbonate aqueous solution was added as a catalyst to the melt obtained by mixing diphenyl carbonate and bisphenol A at a ratio of 1.03 × 10 ⁻⁶ mol with respect to 1 mol of bisphenol A, and the mixture was added to a vertical stirring polymerization tank and a horizontal polymerization tank. The polymerization was carried out while continuously supplying the phenol by-produced while distilling off phenol. The reaction temperature of each reaction tank is in the range of 220 ° C. to 295 ° C., the reaction pressure is in the range of 1.33 × 10 ⁴ Pa to 66 Pa, and the reaction time of each polymerization tank is changed in the range of 30 to 90 minutes to perform the polymerization reaction. To obtain four types of polycarbonates having different molecular weights, DDs and MTs. Under the above reaction conditions, a polycarbonate having a higher molecular weight, DD, and MT as the temperature, the pressure and the polymerization time are longer can be obtained. After the completion of the polymerization, the polycarbonate was fed into a twin-screw extruder in a molten state, and butyl p-toluenesulfonate was continuously kneaded at a molar ratio of 4 times the amount of cesium carbonate used as a catalyst. Then, it was made into a strand shape through a die, cut by a cutter and pelletized. Next, the obtained pellets were dried at 120 ° C. for 4 hours, and physical properties were measured by the methods (i) to (iii) described above. Further, a 5-gallon bottle was manufactured by the method (iv) and evaluated. The results are shown in Table 1.
[0045]
Comparative Example 3
A branched polycarbonate was produced by an interfacial polymerization method using isatin biscresol as a branching agent, bisphenol A as an aromatic dihydroxy compound, and phosgene. The obtained branched polycarbonate was kneaded and pelletized using a 40 mm single screw extruder manufactured by Isuzu Co., Ltd. at a barrel temperature of 290 ° C., dried in the same manner as in Example 1, then measured for physical properties and blown. Production and evaluation of molded articles were performed. In addition, the branching agent content of the obtained branched polycarbonate was 0.26 mol%. The results are shown in Table 1.
[0046]
[Table 1]

[0047]
【The invention's effect】
The aromatic polycarbonate for blow molding of the present invention is excellent in blow moldability, and the blow molded product is excellent in mechanical properties such as impact strength, heat resistance, transparency and appearance, so that dairy product bottles and soft drink bottles , Water bottles and other food containers.

Claims (5)

The viscosity average molecular weight is 24,000 to 30,000, the drawdown property (DD) is 0.250 to 0.450, and the melt tension (MT) satisfies the following formulas (1) and (2). Aromatic polycarbonate for blow molding characterized by the following.

The aromatic polycarbonate for blow molding according to claim 1, wherein the aromatic polycarbonate is produced by a transesterification reaction between a carbonic acid diester and an aromatic dihydroxy compound. The aromatic polycarbonate for blow molding according to claim 2, wherein the aromatic polycarbonate is produced by a transesterification reaction between a carbonic acid diester and an aromatic dihydroxy compound without substantially using a branching agent. A method for producing a molded article, comprising blow molding the aromatic polycarbonate according to any one of claims 1 to 3. The method for producing a molded article according to claim 4, wherein the molded article is a food container.