JP2007105998A - Multilayered molded product, multilayered stretched molded product comprising it and manufacturing method of multilayered molded product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayered molded product which is formed into a multilayered stretched molded product characterized in that the transparency of a bottle even in a long-time continuous molding operation of a large number of bottles using the same heating and stretching mold because the content of a cyclic trimer in an outer layer or inner and outer layers is reduced and the flavor properties of the bottle are also enhanced, the multilayered stretched molded product comprising it and a manufacturing method of the multilayered molded product. <P>SOLUTION: The multilayered molded product comprises at least a thermoplastic polyester layer (A) obtained from a molten polyester after melt polycondensation reaction and a thermoplastic polyester layer (B) with a cyclic trimer content of 8,000 ppm or below, wherein an amorphous carbon vapor deposition layer is laminated to a content contact surface. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a thermoplastic polyester multilayer molded article used for the production of containers such as bottles, a multilayer stretched container comprising the same, and a method for producing the multilayer molded article. More specifically, the present invention relates to a melt-polycondensed thermoplastic polyester. A multilayer molded article having a low content of cyclic trimer and acetaldehyde in the outer layer, and excellent transparency, moldability, gas barrier property, and content flavor, from a melt and a solid-state polymerized thermoplastic polyester And a method for producing the same.

Thermoplastic polyesters are excellent in mechanical and chemical properties, and thus have high industrial value, and are widely used as fibers, films, sheets, bottles and the like.
Among these, polyethylene terephthalate (hereinafter sometimes abbreviated as PET) is excellent in mechanical strength, heat resistance, transparency, and gas barrier properties. It is most suitable as a material for molded articles such as beverage filling containers such as beverages.
Such polyester is supplied to a molding machine such as an injection molding machine to form a preform for a hollow molded body, and the preform is inserted into a mold having a predetermined shape and stretch blow molded to form a hollow for soft drinks. In general, it is formed into a molded container or molded into a heat-resistant or pressure-resistant hollow molded container by heat-treating the preform plug part after heat treatment (crystallization of the plug part) and heat-treating the body part (heat set). Is.

PET contains acetaldehyde (hereinafter sometimes abbreviated as AA) as a by-product during melt polycondensation. In addition, PET produced acetaldehyde by thermal decomposition when thermoforming a molded body such as a hollow molded body, and the acetaldehyde content in the material of the obtained molded body was increased, and the hollow molded body was filled. Affects the flavor and odor of beverages.
For these reasons, various measures have conventionally been taken to reduce the acetaldehyde content in the polyester. As these measures, for example, a method of reducing the AA content by solid-phase polymerization of melt-polycondensed polyester is employed.
However, in the solid phase polymerization method, the operation of cooling the molten polyester resin to form a chip and performing the solid phase polymerization is necessary, and the operation is complicated, and the preform molding is difficult. Therefore, there is a problem in terms of heat energy, for example, the chip must be remelted.

  On the other hand, a condensation injection molding method has been proposed in which PET obtained by melt polycondensation removes acetaldehyde and simultaneously increases the molecular weight (see, for example, Patent Document 1). However, in such a method, in order to increase the intrinsic viscosity, the residence time in the post-polymerization reactor is as long as 30 to 60 minutes, and there are problems in productivity and coloring, and the cyclic trimer content is reduced. There was also a problem that it was not possible.

  Further, after the melt polycondensation reaction, a molten polyester resin obtained through a vented extruder in a molten state and a method for molding the same (for example, see Patent Documents 2, 3, 4, 5, and 6) are already known. Yes. However, since the cyclic trimer content cannot be reduced even by these techniques, the clogging of the mold of the molding machine and the contamination of the heated stretched mold become severe, and a bottle obtained with a long-time operation is obtained. There is a problem that whiteness is reduced, transparency is lowered, and only bottles having no commercial value can be obtained.

JP-A-8-238643 Japanese Patent No. 3684306 Japanese National Patent Publication No. 11-511187 JP-T-2001-516389 JP 2005-171081 A JP 2005-193379 A

  Therefore, the present invention solves the above-mentioned problems of the conventional technique, and since the content of the cyclic trimer in the outer layer is reduced, a long number of bottles are continuously formed using the same heat-stretching mold. Provided are a multilayer molded article that provides a multilayer stretched molded article that maintains the transparency of the bottle even in continuous operation for a long time, and that has improved flavor and gas barrier properties, and a multilayer stretched molded article therefrom, and a method for producing the multilayer molded article. For the purpose.

  The inventors of the present invention have arrived at the present invention as a result of intensive studies to achieve the above object. That is, the multilayer molded body of the present invention includes at least a thermoplastic polyester (A) layer obtained from the melt after the melt polycondensation reaction, and a thermoplastic polyester (B) layer having a cyclic trimer content of 8000 ppm or less. Furthermore, the multilayer molded body is characterized by a multilayer structure in which an amorphous carbon vapor deposition layer is laminated on the content contact surface.

In this case, the layer structure may be three or more layers, the thermoplastic polyester (B) layer may be the outermost layer, and the amorphous carbon vapor deposition layer may be the innermost layer.
Here, when the multilayer molded body is a bottomed multilayer preform, the innermost layer means the innermost layer, the outermost layer means the outermost layer, and the multilayer molded body is a multilayer sheet-like product. In some cases, the outermost layer and the innermost layer are surface layers. In addition, an amorphous carbon vapor deposition layer is always laminated on the inner surface (content contact surface) of the multilayer bottle obtained from the multilayer preform. In the case of a multilayer sheet, the amorphous carbon vapor deposition layer is formed on the content contact surface of food or the like. Are stacked.

  In this case, the content of the thermoplastic polyester (A) layer can be 30 to 99.5% by weight.

  In this case, the thermoplastic polyester (B) can have an intrinsic viscosity of 0.50 to 1.2 dl / g and an acetaldehyde content of 20 ppm or less.

  In this case, the intrinsic viscosity of the thermoplastic polyester (A) can be 0.60 to 0.90 dl / g.

  In this case, at least one layer of the thermoplastic polyester (A) layer or the thermoplastic polyester (B) layer can contain an acetaldehyde reducing agent.

  In this case, the multilayer molded body can be a bottomed multilayer preform or a sheet-like material.

  In this case, it can be a multilayer stretched molded product obtained by stretching the multilayer molded product according to any one of the above in at least one direction.

  Further, a multilayer molded body was molded from the melt of the thermoplastic polyester (A) from the polycondensation reactor after the melt polycondensation reaction and the thermoplastic polyester (B) having a cyclic trimer content of 8000 ppm or less. This is a method for producing a multilayer molded article characterized by laminating an amorphous carbon vapor deposition layer on the content contact surface later.

  The present invention has a low content of cyclic trimer and acetaldehyde in the outer layer from a melt-polycondensed thermoplastic polyester melt and a solid-phase polymerized thermoplastic polyester. Provided are a multilayer molded article having excellent properties and gas barrier properties, a multilayer stretch molded article comprising the same, and a method for producing the same.

  Embodiments of the present invention will be specifically described below.

[Thermoplastic polyester]
The thermoplastic polyester used in the present invention is a polyester substantially derived from a carboxylic acid component mainly composed of one or more aromatic dicarboxylic acid components and an alcohol component mainly composed of one or more glycol components. Polyethylene terephthalate (PET), polyethylene naphthalate (PEN) and the like are typical examples, and polyethylene terephthalate is preferable.

The compositions of the thermoplastic polyester (A) and the thermoplastic polyester (B) are preferably substantially the same. Here, “substantially the same” means that the acid component and the glycol component in each polyester are preferably 95 mol% or more, more preferably 97 mol% or more, particularly 98 mol% or more. Is preferred.
The thermoplastic polyester (A) is a polyester produced only by the melt polycondensation step described below.
On the other hand, the thermoplastic polyester (B) is a polyester obtained by reducing the cyclic trimer content and the acetaldehyde content by further polycondensing the polyester obtained in the melt polycondensation step in the solid phase polymerization step. .

  The polyethylene terephthalate is a linear polyester resin containing 85 mol% or more of ethylene terephthalate units as a main repeating unit, and preferably a linear polyester resin containing 95 mol% or more.

  Examples of the dicarboxylic acid component used by copolymerization in the polyethylene terephthalate include aromatic dicarboxylic acids such as isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl-4,4′-dicarboxylic acid, diphenoxyethanedicarboxylic acid, and the like. Functional derivatives thereof, oxyacids such as p-oxybenzoic acid and oxycaproic acid and functional derivatives thereof, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, succinic acid and glutaric acid and functional derivatives thereof, cyclohexane Examples thereof include alicyclic dicarboxylic acids such as dicarboxylic acids and functional derivatives thereof.

  Examples of the glycol component copolymerized in the polyethylene terephthalate include aliphatic glycols such as diethylene glycol, trimethylene glycol, tetramethylene glycol, and neopentyl glycol, alicyclic glycols such as cyclohexanedimethanol, bisphenol A, and bisphenol A. And aromatic glycols such as alkylene oxide adducts.

  Furthermore, as other copolymer components composed of polyfunctional compounds that can be incorporated into a polyester resin composed of polyethylene terephthalate, examples of the acid component include trimellitic acid and pyromellitic acid, and examples of the glycol component include Examples thereof include glycerin and pentaerythritol. The amount of the copolymer component composed of these polyfunctional compounds must be such that the polyester resin is substantially kept linear.

[Melt polycondensation]
The polyester used in the present invention can be produced by any conventionally known melt polycondensation method. Each raw material is esterified in the presence of an esterification catalyst, and then liquid phase polycondensed in the presence of a polycondensation catalyst to reach a predetermined molecular weight. Examples of the production method include a batch method and a continuous method (single can method, multi-stage method). In the following, an example of a preferable production method in a continuous / multi-stage method will be described using polyethylene terephthalate as an example. It is not limited to.
Direct esterification method in which terephthalic acid and ethylene glycol and other copolymerization components are reacted directly if necessary to distill off water and esterify, and then polycondensation under reduced pressure in the presence of a polycondensation catalyst, or terephthalate It is produced by a transesterification method in which dimethyl acid, ethylene glycol and other copolymerization components are reacted if necessary to distill off methyl alcohol and transesterify, followed by polycondensation under reduced pressure in the presence of a polycondensation catalyst. .

  First, when a low polymer is produced by an esterification reaction, 1.02 to 2.0 mol, preferably 1.03 to 1.95 mol of ethylene glycol is added to 1 mol of terephthalic acid or an ester derivative thereof. The contained slurry is prepared and continuously supplied to the esterification reaction step.

In the esterification reaction, water or alcohol produced by the reaction is removed out of the system by a rectification column under conditions where ethylene glycol is refluxed using a multistage apparatus in which at least two esterification reactors are connected in series. While implementing. The temperature of the esterification reaction in the first stage is 240 to 270 ° C., preferably 245 to 265 ° C., and the pressure is normal pressure to 270 KPa, preferably normal pressure to 250 KPa. The temperature of the esterification reaction in the final stage is usually 250 to 280 ° C., preferably 255 to 275 ° C., and the pressure is usually normal pressure to 250 KPa, preferably normal pressure to 190 KPa.
When carried out in three or more stages, it is preferable to set the reaction conditions for the esterification reaction in the intermediate stage so as to change stepwise from the first stage condition to the final stage condition.
It is desirable that the esterification reaction rate in the final stage reaches 90% or more, preferably 93% or more. By these esterification steps, a low-order condensate having a molecular weight of about 500 to 5,000 is obtained.

  When terephthalic acid is used as a raw material, the esterification reaction can be carried out without a catalyst by the catalytic action of terephthalic acid as an acid, but may be carried out in the presence of a polycondensation catalyst.

In addition, ethylene glycol may dimerize to generate diethylene glycol, which may be copolymerized in the main chain to reduce the strength of the resin. To prevent this, tertiary amines such as triethylamine, tri-n-butylamine and benzyldimethylamine, and quaternary ammonium hydroxides such as tetraethylammonium hydroxide, tetra-n-butylammonium hydroxide and trimethylbenzylammonium hydroxide are used. It is also preferable to add a small amount of a basic compound such as lithium carbonate, sodium carbonate, potassium carbonate or sodium acetate.
The proportion of dioxyethylene terephthalate component units in the main chain of polyethylene terephthalate is preferably 5 mol% or less with respect to the total diol component.

  Next, in the case of producing a low polymer by transesterification, 1.1 to 2.0 mol, preferably 1.2 to 1.5 mol of ethylene glycol was contained with respect to 1 mol of dimethyl terephthalate. The solution is prepared and continuously fed to the transesterification step.

  The transesterification reaction is carried out while removing methanol generated by the reaction outside the system using a rectification column under the condition that ethylene glycol is distilled back using an apparatus in which 1 to 2 transesterification reactors are connected in series. To do. The temperature of the first stage transesterification is 180 to 250 ° C, preferably 200 to 240 ° C. The temperature of the transesterification reaction in the final stage is usually 230 to 270 ° C., preferably 240 to 265 ° C., and as the transesterification catalyst, fatty acid salts such as Zn, Cd, Mg, Mn, Co, Ca, Ba, carbonates Further, Pb, Zn, Ge oxide or the like is used. A low-order condensate having a molecular weight of about 200 to 500 is obtained by these transesterification reactions.

Dimethyl terephthalate, terephthalic acid or ethylene glycol, which is the starting material, includes virgin dimethyl terephthalate derived from para-xylene, ethylene glycol derived from terephthalic acid or ethylene, as well as methanol decomposition from used PET bottles. A recovered raw material such as dimethyl terephthalate, terephthalic acid, bishydroxyethyl terephthalate or ethylene glycol recovered by a chemical recycling method such as decomposition of ethylene glycol or ethylene glycol can also be used as at least part of the starting material. Needless to say, the quality of the recovered raw material must be refined to a purity and quality suitable for the intended use.
The resulting low-order condensate is then fed to a multi-stage liquid phase polycondensation process. Regarding the polycondensation reaction conditions, the reaction temperature of the first stage polycondensation is 250 to 290 ° C, preferably 260 to 280 ° C, and the pressure is 500 to 20 torr, preferably 200 to 30 torr. The temperature of the final stage polycondensation reaction is 265 to 300 ° C, preferably 275 to 295 ° C, and the pressure is 10 to 0.1 torr, preferably 5 to 0.5 torr.
When carried out in three or more stages, it is preferable to set the reaction conditions for the esterification reaction in the intermediate stage so as to change stepwise from the first stage condition to the final stage condition. The degree of increase in intrinsic viscosity (IV) achieved in each of these polycondensation reaction steps is preferably distributed smoothly.

  The polycondensation reaction is performed using a polycondensation catalyst. As the polycondensation catalyst, at least one compound selected from Ge, Ti, Sb or Al compounds is preferably used. These compounds are added to the reaction system as powders, aqueous solutions, ethylene glycol solutions, ethylene glycol slurries and the like.

  Examples of the Ge compound include amorphous germanium dioxide, crystalline germanium dioxide powder or ethylene glycol slurry, a solution obtained by heating and dissolving crystalline germanium dioxide in water, or a solution obtained by adding ethylene glycol to this and heat treatment. In particular, in order to obtain the polyester used in the present invention, it is preferable to use a solution in which germanium dioxide is dissolved by heating in water, or a solution in which ethylene glycol is added and heated. In addition, compounds such as germanium tetroxide, germanium hydroxide, germanium oxalate, germanium chloride, germanium tetraethoxide, germanium tetra-n-butoxide, and germanium phosphite can also be used. These polycondensation catalysts can be added during the esterification step. When a Ge compound is used, the amount used is 10 to 100 ppm, preferably 10 to 60 ppm, more preferably 13 to 50 ppm, and still more preferably 15 to 45 ppm as the residual amount of Ge in the polyester.

  Examples of Ti compounds include tetraethyl titanates, tetraisopropyl titanates, tetra-n-propyl titanates, tetraalkyl titanates such as tetra-n-butyl titanates and partial hydrolysates thereof, titanium acetate, titanyl oxalate, titanyl ammonium oxalate, titanyl oxalate Sodium, titanyl oxalate, titanyl calcium oxalate, titanyl succinate, titanyl succinate, titanium trimellitic acid, titanium sulfate, titanium chloride, titanium halide hydrolyzate, titanium oxalate, titanium fluoride, titanium hexafluoride Titanium with potassium acid, ammonium hexafluorotitanate, cobalt hexafluorotitanate, manganese hexafluorotitanate, titanium acetylacetonate, hydroxy polyvalent carboxylic acid or nitrogen-containing polyvalent carboxylic acid A phosphorus compound is reacted with a complex compound, a composite oxide composed of titanium and silicon or zirconium, a reaction product of titanium alkoxide and a phosphorus compound, or a reaction product of titanium alkoxide and an aromatic polycarboxylic acid or its anhydride. The reaction product obtained by the above. The Ti compound is added so that the amount of Ti remaining in the produced polymer is 0.1 to 50 ppm, preferably 0.5 to 20 ppm, and most preferably 0.5 to 10 ppm.

  Examples of the Sb compound include antimony trioxide, antimony acetate, antimony tartrate, antimony potassium tartrate, antimony oxychloride, antimony glycolate, antimony pentoxide, and triphenylantimony. The Sb compound is added so that the residual amount of Sb in the produced polymer is in the range of 50 to 300 ppm, preferably 50 to 250 ppm, preferably 50 to 200 ppm, and more preferably 50 to 180 ppm.

  Al compounds include aluminum acetate, basic aluminum acetate, aluminum chloride, aluminum hydroxide, aluminum hydroxide chloride, aluminum carbonate, aluminum phosphate, aluminum phosphonate and other inorganic acid salts, aluminum n-propoxide, aluminum iso-propoxide Aluminum alkoxides such as aluminum n-butoxide and aluminum t-butoxide, aluminum chelate compounds such as aluminum acetylacetonate, aluminum acetylacetate, aluminum ethylacetoacetate, aluminum ethylacetoacetate diiso-propoxide, trimethylaluminum, triethylaluminum, etc. Organic aluminum compounds and partial hydrolysates thereof, aluminum oxide, etc. It is. Of these, aluminum acetate, basic aluminum acetate, aluminum chloride, aluminum hydroxide, aluminum hydroxide chloride and aluminum acetylacetonate are particularly preferred. The Al compound is added so that the residual amount of Al in the produced polymer is in the range of 5 to 100 ppm, preferably 10 to 50 ppm, and most preferably 10 to 30 ppm.

  In the production of the polyester according to the present invention, an alkali metal compound or an alkaline earth metal compound may be used in combination as necessary. The alkali metal or alkaline earth metal is preferably at least one selected from Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, and Ba, and the use of an alkali metal or a compound thereof is preferable. More preferred. When using an alkali metal or a compound thereof, use of Li, Na, K is particularly preferable. Examples of the alkali metal and alkaline earth metal compounds include saturated aliphatic carboxylates such as formic acid, acetic acid, propionic acid, butyric acid, and succinic acid, and unsaturated aliphatic carboxylates such as acrylic acid and methacrylic acid. , Aromatic carboxylates such as benzoic acid, halogen-containing carboxylates such as trichloroacetic acid, hydroxycarboxylates such as lactic acid, citric acid and salicylic acid, carbonic acid, sulfuric acid, nitric acid, phosphoric acid, phosphonic acid, hydrogen carbonate, phosphorus Inorganic acid salts such as acid hydrogen, hydrogen sulfide, sulfurous acid, thiosulfuric acid, hydrochloric acid, hydrobromic acid, chloric acid and bromic acid, and organic sulfonates such as 1-propanesulfonic acid, 1-pentanesulfonic acid and naphthalenesulfonic acid , Organic sulfates such as lauryl sulfate, methoxy, ethoxy, n-propoxy, iso-propoxy, n-butoxy, tert-butyl Alkoxides such as alkoxy, chelate compounds and the like acetylacetonate, hydrides, oxides, and hydroxides and the like.

  The alkali metal compound or alkaline earth metal compound is added to the reaction system as a powder, an aqueous solution, an ethylene glycol solution, or the like. The alkali metal compound or alkaline earth metal compound is added so that the residual amount of these elements in the produced polymer is in the range of 1 to 50 ppm.

  Furthermore, the polyester according to the present invention contains at least one element selected from the group consisting of silicon, manganese, iron, cobalt, zinc, gallium, strontium, zirconium, niobium, molybdenum, indium, tin, hafnium, and thallium. You may contain the metal compound to contain. These metal compounds include saturated aliphatic carboxylates such as acetates of these elements, unsaturated aliphatic carboxylates such as acrylates, aromatic carboxylates such as benzoic acid, and halogens such as trichloroacetic acid. Hydroxycarboxylates such as carboxylates and lactates, inorganic acid salts such as carbonates, organic sulfonates such as 1-propanesulfonate, organic sulfates such as lauryl sulfate, oxides, hydroxides, chlorides Products, alkoxides, acetylacetonates and the like, and are added to the reaction system as powders, aqueous solutions, ethylene glycol solutions, ethylene glycol slurries and the like. These metal compounds are added so that the residual amount of elements of these metal compounds per 1 ton of produced polymer is in the range of 0.05 to 3.0 mol. These metal compounds can be added at any stage of the polyester formation reaction step.

  Further, as stabilizers, phosphoric acid, phosphoric acid esters such as polyphosphoric acid and trimethyl phosphate, phosphonic acid compounds, phosphinic acid compounds, phosphine oxide compounds, phosphonous acid compounds, phosphinic acid compounds, phosphine compounds It is preferable to use at least one phosphorus compound selected from the group consisting of: Specific examples include phosphoric acid, phosphoric acid trimethyl ester, phosphoric acid triethyl ester, phosphoric acid tributyl ester, phosphoric acid triphenyl ester, phosphoric acid monomethyl ester, phosphoric acid dimethyl ester, phosphoric acid monobutyl ester, phosphoric acid dibutyl ester, Phosphoric acid, phosphorous acid trimethyl ester, phosphorous acid triethyl ester, phosphorous acid tributyl ester, methylphosphonic acid, methylphosphonic acid dimethyl ester, ethylphosphonic acid dimethyl ester, phenylphosphonic acid dimethyl ester, phenylphosphonic acid diethyl ester, phenylphosphonic acid Diphenyl ester and the like. These stabilizers can be added during the esterification reaction step from a slurry preparation tank of terephthalic acid and ethylene glycol. The P compound is added so that the residual amount of P in the produced polymer is in the range of 1 to 1000 ppm, preferably 5 to 100 ppm, and most preferably 5 to 50 ppm.

  When an Al compound is used as the polycondensation catalyst, it is preferably used in combination with a phosphorus compound, and is preferably used as a solution or slurry in which an aluminum compound and a phosphorus compound are previously mixed in a solvent. In the case of an Al compound, a more preferable phosphorus compound is at least one selected from the group consisting of phosphonic acid compounds, phosphinic acid compounds, phosphine oxide compounds, phosphonous acid compounds, phosphinic acid compounds, and phosphine compounds. It is a phosphorus compound. By using these phosphorus compounds, an effect of improving the catalytic activity is seen, and an effect of improving physical properties such as thermal stability of the polyester is seen. Among these, use of a phosphonic acid compound is preferable because of its great effect of improving physical properties and improving catalytic activity. Among the above-described phosphorus compounds, the use of a compound having an aromatic ring structure is preferable because the physical property improving effect and the catalytic activity improving effect are great.

  The intrinsic viscosity of the thermoplastic polyester (A) melt used in the present invention is 0.60 to 0.90 dl / g, preferably 0.65 to 0.85 dl / g, more preferably 0.70 to 0.80 dl. / G, most preferably in the range of 0.75 to 0.85 dl / g. When the intrinsic viscosity of the polyester is less than 0.60 dl / g, the mechanical properties of the obtained molded article and the like are poor. In addition, when the intrinsic viscosity of the polyester exceeds 0.90 dl / g, the resin temperature becomes high at the time of melting by a molding machine or the like, the thermal decomposition becomes severe, and free low molecular weight compounds that affect the fragrance retention increase. Or the molded body is colored yellow.

  The amount of diethylene glycol copolymerized in the thermoplastic polyester (A) is 1.0 to 5.0 mol%, preferably 1.5 to 4.5 mol, of the glycol component constituting the polyester. %, More preferably 1.8 to 4.0 mol%, still more preferably 2.0 to 3.0 mol%, particularly preferably 2.0 to 2.9 mol%. When the amount of diethylene glycol exceeds 5.0 mol%, the thermal stability is deteriorated, the molecular weight decrease is greatly increased during the deaeration treatment, and the effect of reducing the acetaldehyde content is deteriorated. On the other hand, when the diethylene glycol content is less than 1.0 mol%, the transparency of the obtained multilayer molded article is deteriorated.

When the thermoplastic polyester (A) used in the present invention is PET, the content of the cyclic trimer of the thermoplastic polyester (A) melt is about 10,000 ppm, and cannot be reduced below this by melt polycondensation. .
Further, when the innermost layer of the multilayer stretched molded article is made of the thermoplastic polyester (B), the acetaldehyde content of the thermoplastic polyester (A) melt used in the present invention is about 100 ppm or less, preferably 70 ppm or less, more preferably It is desirable that it is 50 ppm or less, most preferably 20 ppm or less. When the acetaldehyde content of the thermoplastic polyester (A) melt exceeds 100 ppm, the amount of acetaldehyde transferred to the contents increases depending on the thickness of the innermost layer and the time elapsed from molding to filling the contents. Flavor may deteriorate, which is a problem.

When the innermost layer of the multilayer stretched molded article is made of thermoplastic polyester (A), the acetaldehyde content of the thermoplastic polyester (A) melt used in the present invention is 30 ppm or less, preferably 20 ppm or less, more preferably 15 ppm. Hereinafter, it is most preferably 10 ppm or less.
As a method of reducing the acetaldehyde content of the thermoplastic polyester (A) melt, for example, a method of reducing the heat history in the molten state from the end of the polycondensation reaction to the molding of the multilayer molded body as much as possible, Examples include a method of degassing the melt before supply, a method of adding an acetaldehyde reducing agent, and a method of appropriately combining these methods.

In the case of the method of reducing the heat history of the melt, the resin temperature from the end of the polycondensation reaction to the formation of the multilayer molded body is 250 to 300 ° C, preferably 250 to 290 ° C, more preferably 250 to 280 ° C, most preferably It is preferably in the range of 250 to 270 ° C., and the melt residence time is within 20 minutes, preferably within 10 minutes, and most preferably within 5 minutes.
Further, in order to further reduce the acetaldehyde content of the thermoplastic polyester (A) melt used in the present invention, it is deaerated with a vent type extruder or the like before being transported to the step of forming the multilayer molded body. I can do it.

In the case of deaeration treatment, the apparatus used for the deaeration treatment is not particularly limited as long as the kneading of the molten resin and the deaeration of acetaldehyde are performed effectively, but in terms of the removal efficiency of acetaldehyde, extrusion with a vent is performed. Machine is preferred. As the extruder with a vent, either a single-screw extruder or a twin-screw extruder can be used, but a twin-screw extruder is preferable because of high stirring efficiency and acetaldehyde reduction efficiency. Note that the screw of the twin-screw extruder may be any of a meshing type, a non-meshing type, and an incomplete meshing type, or any of the same direction and different direction rotations.

  When the innermost layer of the multilayer molded article of the present invention is made of the thermoplastic polyester (B), the acetaldehyde content of the thermoplastic polyester (A) melt before the degassing treatment is about 150 ppm or less, preferably 100 ppm or less, more preferably Is desirably 50 ppm or less. If the acetaldehyde content of the thermoplastic polyester (A) melt before the deaeration treatment exceeds 150 ppm, the acetaldehyde content of the thermoplastic polyester (A) layer after the deaeration treatment cannot be reduced to 100 ppm or less.

  Further, when the innermost layer of the multilayer molded body of the present invention is composed of the thermoplastic polyester (A), the acetaldehyde content of the thermoplastic polyester (A) melt before the degassing treatment is about 80 ppm or less, preferably 70 ppm or less, More preferably, it is 50 ppm or less. If the acetaldehyde content of the thermoplastic polyester (A) melt before the deaeration treatment exceeds 80 ppm, the acetaldehyde content of the thermoplastic polyester (A) layer is reduced to 30 ppm or less even if the deaeration treatment of the present invention is performed. This is a problem in terms of flavor.

The color b value of the thermoplastic polyester (A) before degassing is 4 or less, more preferably 3.0 or less, further preferably 2.5 or less, particularly preferably 2.0 or less, and most preferably 1. .5 or less is preferable. If the color b value exceeds 4, the hue of the multilayer molded product is poor, which is a problem.

The deaeration treatment is carried out at a temperature not lower than the melting temperature of the thermoplastic polyester and not higher than 300 ° C. at a pressure of 0.01 to 50 torr, preferably 0.01 to 20 torr, more preferably 0.01 to 10 torr. The acetaldehyde should be removed in a short time of 1 to 10 minutes. The resin temperature during the degassing treatment is preferably in the range of 250 ° C to 290 ° C. The residence time is preferably 10 minutes or less, more preferably 5 minutes or less, still more preferably 4 minutes or less, particularly preferably 3 minutes or less, and most preferably 2 minutes or less.

As in the present invention, when the deaeration treatment is performed from the resin using an extruder with a vent, the resin is considerably colored compared to the case where solid phase polymerization is performed after conventional melt polycondensation or melt polycondensation. Become stronger. This is a characteristic phenomenon when dealdehyde is removed from the resin using a vented extruder. This is because of the heat generated by the screw and barrel of the extruder, the deterioration of the resin due to the local temperature rise due to the heating of the heater of the barrel, and some vacuum leakage between the barrels in the vented extruder. It is considered that the resin is decomposed because the resin is exposed to oxygen-containing air.
In the case of deaeration treatment, the polyester resin prevents coloring due to an increase in residence time in the vented extruder, so that the intrinsic viscosity after the vented extruder-the intrinsic viscosity before the extruder is -0.1 to 0. The treatment is preferably performed in the range of 08 dl / g, more preferably in the range of -0.08 to 0.05 dl / g, still more preferably in the range of -0.05 to 0.02 dl / g, most preferably. It is preferable to treat in the range of −0.03 to 0 dl / g.

  The color b value of the degassed thermoplastic polyester (A) is 4 or less, more preferably 3.0 or less, further preferably 2.5 or less, particularly preferably 2.0 or less, and most preferably 1.5 or less. It is preferable that If the color b value exceeds 4, the hue of the multilayer molded product is poor, which is a problem.

  By adding a hindered phenol-based antioxidant, the above-mentioned coloring can be further prevented. As such a hindered phenol-based antioxidant, a known one may be used. For example, pentaerythritol-tetra extract [3- (3,5-di-tert-butyl-4-hydrate 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5- Trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, 3,9-bis {2- [3- (3-tert-butyl-4-hydroxy-5) -Methyl 3- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy) -1,1-dimethylethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane, 1,3,5- Lis (4-tert-butyl-3-hydroxy-2,6-dimethylbenzene) isophthalic acid, triethylglycol-bis [3- (3-tert-butyl-5-methyl-4-hydroxy 3- (3-tert- Butyl-5-methyl-4-hydroxyphenyl) propionate), 1,6-hexanediol-bis [3- (3,3- (3,5-di-tert-butyl-4-hydroxyphenyl) bropionate), 2 , 2-thio-diethylene-bis [3- (3,5-di-tert-butyl-4-hydroxyph-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate), octadecyl-3 -(3,5-di-tert-butyl-4-hydroxyphenyl) propionate], ethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, 3,5-di-tert- Methyl 4-methylbenzyl phosphonate, 3,5-di-tert-butyl-4-hydroxybenzyl phosphonate, phenyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, 3,5- Examples include octadecyl di-tert-butyl-4-hydroxybenzylphosphonate and 3,5-di-tert-butyl-4-hydroxybenzylphosphonic acid.

In this case, the hindered phenol-based oxidation stabilizer may be bonded to the polyester, and the amount of the hindered phenol-based oxidation stabilizer in the polyester is preferably 1% by weight or less based on the weight of the polyester product. Preferably, it is 0.02 to 0.5 weight%.
The hindered phenol-based oxidation stabilizer may be added during the esterification reaction step or may be added during the polycondensation reaction step. Furthermore, it may be added to any of the steps up to the feed in the vented extruder or the vent-like extruder. Of course, it may be added sequentially for each step.
The polyester thus obtained is used as one constituent layer of the multilayer molded body as the thermoplastic polyester (A) in the present invention.

[Solid phase polymerization]
The melt polycondensation polyester obtained as described above is, for example, a method in which the melt polyester is extruded into water from the die pores after completion of the melt polycondensation and cut in water, or after the melt polycondensation is finished in the air from the die pores. After being extruded into strands, the chips are formed into columns, spheres, squares or plates by a method of forming chips while cooling with cooling water. Further, after being extruded into a sheet form from the die slit in air or water, it is formed into a sheet-like product while being cooled with cooling water. At this time, it is necessary to obtain the thermoplastic polyester (B) according to the present invention by making the temperature in the molten state up to the die as low as possible and making the residence time as short as possible. It is matter.

In addition, as the cooling water at the time of forming the melt polycondensed polyester into chips, it is preferable to use cooling water satisfying at least one of the following formulas (1) to (4), and more preferably formula (1) to It is most preferable to use water that satisfies all of (4).
Na ≦ 1.0 (ppm) (1)
Mg ≦ 1.0 (ppm) (2)
Si ≦ 2.0 (ppm) (3)
Ca ≦ 1.0 (ppm) (4)

The sodium content (Na) in the cooling water is preferably Na ≦ 0.5 ppm, more preferably Na ≦ 0.1 ppm. The magnesium content (Mg) in the cooling water is preferably Mg ≦ 0.5 ppm, more preferably Mg ≦ 0.1 ppm. Further, the content (Si) of silicon in the cooling water is preferably Si ≦ 0.5 ppm, more preferably Si ≦ 0.3 ppm. Furthermore, the calcium content (Ca) in the cooling water is preferably Ca ≦ 0.5 ppm, and more preferably Ca ≦ 0.1 ppm.
In order to reduce sodium, magnesium, calcium, and silicon in the cooling water, an apparatus for removing sodium, magnesium, calcium, and silicon is installed in at least one place until the industrial water is sent to the chip cooling process. Also, a filter is installed to remove clay minerals such as silicon dioxide and aluminosilicate particles. Examples of the device for removing sodium, magnesium, calcium, and silicon include an ion exchange device, an ultrafiltration device, and a reverse osmosis membrane device.

  Next, the previous melt polycondensed polyester chip is preferably pre-crystallized in a continuous crystallization apparatus having two or more stages in an inert gas atmosphere. For example, in the case of PET, the temperature of 100 to 180 ° C. is 1 minute to 5 hours in the first stage precrystallization, and then the temperature of 160 to 210 ° C. is 1 minute to 3 hours in the second stage precrystallization. In the pre-crystallization of the second and higher stages, it is preferable to perform crystallization step by step at a temperature of 180 to 210 ° C. for 1 minute to 3 hours. The crystallinity of the chip after crystallization is preferably in the range of 30 to 65%, preferably 35 to 63%, and more preferably 40 to 60%. The crystallinity can be obtained from the density of the chip.

  Next, solid phase polymerization is performed in an inert gas atmosphere or under reduced pressure at an optimum temperature for the prepolymer so that the increase in intrinsic viscosity due to solid phase polymerization is 0.10 dl / g or more. For example, in the case of PET, the upper limit of the solid phase polymerization temperature is preferably 215 ° C. or lower, more preferably 210 ° C. or lower, particularly 208 ° C. or lower, and the lower limit is 190 ° C. or higher, preferably 195 ° C. or higher. is there.

  In order to prevent the generation of acetaldehyde after completion of the solid phase polymerization, the chip temperature is about 70 ° C. or less, preferably 60 ° C. or less, more preferably 50 ° C. or less within about 30 minutes, preferably within 20 minutes, more preferably within 10 minutes. The following is preferable.

The intrinsic viscosity of the thermoplastic polyester (B) is 0.50 to 1.2 dl / g, preferably 0.6 to 0.90 dl / g, more preferably 0.70 to 0.80 dl / g, and most preferably 0. Desirably, it is in the range of .75 to 0.85 dl / g. When the intrinsic viscosity of the thermoplastic polyester is less than 0.50 dl / g, the mechanical properties of the obtained molded article are poor. In addition, when the intrinsic viscosity of the thermoplastic polyester exceeds 1.2 dl / g, the resin temperature becomes high at the time of melting by a molding machine or the like, the thermal decomposition becomes severe, and a free low molecular weight compound that affects the fragrance retention Problems such as an increase and the molded body are colored yellow occur.
Further, the amount of diethylene glycol copolymerized in the thermoplastic polyester (B) is 1.0 to 5.0 mol% of the glycol component constituting the polyester, like the thermoplastic polyester (A), preferably Is 1.5 to 4.5 mol%, more preferably 1.8 to 4.0 mol%, still more preferably 2.0 to 3.0 mol%, particularly preferably 2.0 to 2.9 mol%. Preferably there is.

  The content of the cyclic trimer of the thermoplastic polyester (B) according to the present invention is desirably 8000 ppm or less, preferably 5000 ppm or less, more preferably 4000 ppm or less. When forming a heat-resistant hollow molded body or the like from the multilayer molded body of the present invention, heat treatment is performed in a heating mold, but when the content of the cyclic trimer exceeds 8000 ppm, the surface of the heating mold Oligomer adhesion to the water increases rapidly, and the transparency of the obtained hollow molded article or the like is extremely deteriorated.

  The acetaldehyde content of the thermoplastic polyester (B) according to the present invention is desirably 20 ppm or less, preferably 15 ppm or less, more preferably 10 ppm or less. In particular, when the polyester composition of the present invention is used as a material for a container for low flavor beverages such as mineral water, the acetaldehyde content of the polyester is 8 ppm or less, preferably 6 ppm or less, more preferably 5 ppm or less. It is desirable that When the acetaldehyde content exceeds 20 ppm, the effect of flavor retention of the contents such as a molded article molded from this polyester composition is deteriorated. Further, these lower limits are preferably 0.1 ppb from the viewpoint of production.

The thermoplastic polyester (B) is preferably obtained by deactivating the polycondensation catalyst. Examples of a method for deactivating the polyester polycondensation catalyst include a method in which a polyester chip is contacted with water, water vapor or a water vapor-containing gas after solid phase polymerization.
As another means of deactivating the polycondensation catalyst, a phosphorus compound is blended with the thermoplastic polyester (B) after solid-phase polymerization, and mixed and reacted in the molten state at the time of molding or the like to inactivate the polycondensation catalyst. The method of making it.

  The shape of the thermoplastic polyester (B) chip according to the present invention may be any of a cylinder shape, a square shape, a spherical shape, a flat plate shape, and the like. The average particle diameter is usually 1.0 to 4 mm, preferably 1.0 to 3.5 mm, and more preferably 1.0 to 3.0 mm. For example, in the case of a cylinder type, it is practical that the length is about 1.0 to 4 mm and the diameter is about 1.0 to 4 mm. In the case of spherical particles, it is practical that the maximum particle size is 1.1 to 2.0 times the average particle size and the minimum particle size is 0.7 times or more the average particle size. The weight of the chip is practically in the range of 5 to 40 mg / piece.

The fine content in the thermoplastic polyester (B) according to the present invention is 0.1 to 5000 ppm, preferably 0.1 to 3000 ppm, more preferably 0.1 to 1000 ppm, still more preferably 0.1 to 500 ppm, Most preferably, it is 0.1-100 ppm. When the fine content exceeds 5000 ppm, the crystallization speed of the multilayer molded body increases, and only a molded body with poor transparency can be obtained. In addition, reducing the fine content to less than 0.1 is economically problematic.
The thermoplastic polyester (B) obtained by solid phase polymerization as described above is used as one constituent layer of a multilayer molded body.

[Acetaldehyde reducing agent]
In order to reduce the acetaldehyde content of the thermoplastic polyester (A) melt or the thermoplastic polyester (B) according to the present invention, it is preferable to use an acetaldehyde reducing agent.
Examples of the acetaldehyde reducing agent used in the present invention include a hydroxyl group-containing polymer such as polyamide, polyesteramide, and polyvinyl alcohol, a low molecular weight amino group-containing compound, a low molecular weight hydroxyl group-containing compound, a hindered phenyl compound, and a hindered amine compound. Examples thereof include compounds, benzotriazole compounds, benzophenone compounds, polyphenol compounds, phosphorus stabilizers, sulfur stabilizers, alkali metals and organic salts thereof.

Examples of the polyamide blended as the acetaldehyde reducing agent include at least one polyamide selected from aliphatic polyamide and partially aromatic polyamide.
Specific examples of the aliphatic polyamide include nylon 6, nylon 11, nylon 12, nylon 66, nylon 69, nylon 610, nylon 6/66, nylon 6/610, and the like.
As a preferable example of the partially aromatic polyamide, a structural unit derived from metaxylylenediamine or a mixed xylylenediamine containing metaxylylenediamine and 30% or less of the total amount of paraxylylenediamine and an aliphatic dicarboxylic acid is used. A metaxylylene group-containing polyamide containing at least 20 mol% or more, more preferably 30 mol% or more, particularly preferably 40 mol% or more in the molecular chain.
Further, the partially aromatic polyamide may contain a structural unit derived from a polybasic carboxylic acid having 3 or more bases such as trimellitic acid and pyromellitic acid within a substantially linear range.

Examples of these polyamides include homopolymers such as polymetaxylylene adipamide, polymetaxylylene sebacamide, polymetaxylylene speramide, and metaxylylenediamine / adipic acid / isophthalic acid copolymers, metaxylylene. / Paraxylylene adipamide copolymer, metaxylylene / paraxylylene piperamide copolymer, metaxylylene / paraxylylene azelamide copolymer, metaxylylenediamine / adipic acid / isophthalic acid / ε-caprolactam copolymer And metaxylylenediamine / adipic acid / isophthalic acid / ω-aminocaproic acid copolymer.
In addition, other preferable examples of the partially aromatic polyamide include at least 20 mol% or more of a structural unit derived from an aliphatic diamine and at least one acid selected from terephthalic acid or isophthalic acid, A polyamide containing 30 mol% or more, particularly preferably 40 mol% or more is preferred.

  Examples of these polyamides include polyhexamethylene terephthalamide, polyhexamethylene isophthalamide, hexamethylene diamine / terephthalic acid / isophthalic acid copolymer, polynonamethylene terephthalamide, polynonamethylene isophthalamide, nonamethylene diamine / terephthalic acid. / Isophthalic acid copolymer, nonamethylenediamine / terephthalic acid / adipic acid copolymer, and the like.

Other preferable examples of the partially aromatic polyamide include, in addition to at least one acid selected from aliphatic diamine and terephthalic acid or isophthalic acid, lactams such as ε-caprolactam and laurolactam, and amino such as aminocaproic acid. Derived from an aliphatic diamine and at least one acid selected from terephthalic acid or isophthalic acid obtained by using carboxylic acids, aromatic aminocarboxylic acids such as para-aminomethylbenzoic acid, etc. as copolymerization components The polyamide contains at least 20 mol% or more, more preferably 30 mol% or more, particularly preferably 40 mol% or more in the molecular chain.
Examples of these polyamides include hexamethylenediamine / terephthalic acid / ε-caprolactam copolymer, hexamethylenediamine / isophthalic acid / ε-caprolactam copolymer, hexamethylenediamine / terephthalic acid / adipic acid / ε-caprolactam copolymer Examples include coalescence.

  Polyester amides include terephthalic acid, polyester amide produced from 1,4-cyclohexanedimethanol and polyethyleneimine, polyester amide produced from isophthalic acid, 1,4-cyclohexanedimethanol and hexamethylenediamine, and terephthalic acid. Polyesteramides made from adipic acid, 1,4-cyclohexanedimethanol and hexamethylenediamine, polyesteramides made from terephthalic acid, 1,4-cyclohexanedimethanol and bis (p-aminocyclohexyl) methane and their A mixture etc. are mentioned. Examples of the acid component that can be used as a copolymerization component include aliphatic compounds such as sebacic acid, malonic acid, succinic acid, glutaric acid, pimelic acid, spellic acid, azelaic acid, undecanoic acid, undecadioic acid, dodecanedioic acid, and dimer acid. Dicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, alicyclic dicarboxylic acid such as 1,3-cyclohexanedicarboxylic acid, alicyclic dicarboxylic acid such as 1,2-cyclohexanedicarboxylic acid, orthophthalic acid, xylylene dicarboxylic acid, naphthalene Aromatic dicarboxylic acids such as dicarboxylic acids can be mentioned.

  The polyamide or polyester amide used preferably has a secondary transition point measured by DSC (differential scanning calorimeter) of 50 to 120 ° C. When the secondary transition point is less than 50 ° C., it is not preferable because it is fused during the drying step or extrusion with the polyester resin or cannot be quantitatively extruded. Moreover, when exceeding 120 degreeC, when extending | stretching a polyester unstretched molded object, it will not be stretched | homogenized uniformly but a thickness spot etc. will arise and it is not preferable.

Examples of the hydroxyl group-containing polymer include polyvinyl alcohol and ethylene vinyl alcohol polymer.
Examples of the low molecular weight hydroxyl group-containing compounds include sugar alcohols, triglycerin, trimethylolpropane, sorbitol, mannitol, xylitol, dextrin, cyclodextrin, pentaerythritol, dipentaerythritol, and the like, and alkoxylated polyols thereof. It is done.

Examples of the low molecular weight amino group-containing compound include aliphatic amine compounds such as stearylamine, o-phenylenediamine, 3,4-diaminobenzoic acid, 1,8-diaminonaphthalene, N, N′-1,6- Aromatic amine compounds such as hexanedibis (2-aminobenzamide), 4,4′-diaminodiphenylmethane, anthranilamides, salicylamides, salicylanilides, o-mercaptobenzamides, N-acetylglycinamides, malonamides, 2-amino Acid amide compounds such as benzenesulfonamide, diamino compounds such as 2,3-diaminopyridine, 1,2-diaminoanthraquinone and dianilinoethane, triazine compounds such as melamine and benzoguanamine, 4-amino-3-hydroxybenzoic acid, 2-amino-2- Compounds functional groups such as chill-1,3-propanediol is an amino group and Hidokishiru groups, amino and the like.
These acetaldehyde reducing agents such as polyamide compounds, low molecular weight amino group-containing compounds, or hydroxyl group-containing compounds may be used alone or in admixture at an appropriate ratio.

Further, when it is inconvenient to use the low molecular weight acetaldehyde reducing agent as it is, it is used as a concentrated master batch (hereinafter sometimes abbreviated as “MB”) with the thermoplastic polyester (B). It is more convenient to use.
The acetaldehyde reducing agent is, for example, used in an amount of 0.001 to 5 parts by weight, preferably 0.01 to 3 parts by weight, and more preferably 0.1 to 2 parts by weight with respect to 100 parts by weight of the thermoplastic polyester according to the present invention. be able to. If it is less than 0.001% by weight, the effect of reducing the acetaldehyde content is lost, which is a problem. On the other hand, if it exceeds 5% by weight, the transparency and color tone of the molded article are deteriorated.

  The acetaldehyde reducing agent can be blended, for example, by adding a predetermined amount of acetaldehyde reducing agent in any reaction stage from the production of the low-polymerization degree oligomer of the thermoplastic polyester (B) to the production of the polyester polymer. . If the acetaldehyde reducing agent is a high molecular weight resin, it may be in the form of a fine particle, powder, melt, or solution, and if it is a low molecular weight compound, it may be in the form of a powder or solution. The acetaldehyde-reducing agent or the polyester and the polyester are added to a reactor such as a hydration reactor or a polycondensation reactor, or in the transport pipe of the polyester reactant from the reactor to a reactor in the next step. The mixture can be blended by introducing it in a molten state. Furthermore, if necessary, the obtained chip can be subjected to solid phase polymerization in a high vacuum or in an inert gas atmosphere.

[Recycled products]
For the thermoplastic polyester (A) layer and the thermoplastic polyester (B) layer according to the present invention, after the polyester is heated and melted by a melt molding machine such as an injection molding machine, the product is formed into a form or a sheet-like product. It is possible to collect the recovered polyester and the used polyester container, and mix the flake-shaped or chip-shaped polyester that has undergone the steps of foreign matter removal, washing, drying, or re-extrusion. The intrinsic viscosity of these recycled products is preferably about 0.60 to 0.80 dl / g. The blending amount is preferably in the range of 1 to 50% by weight.

[Multilayer molded product]
In the present invention, the thermoplastic polyester (A) melt obtained by melt polycondensation is subjected to a multi-layer preform molding machine or the like by a transportation means such as an extruder or a gear pump, with or without a degassing treatment step. It is transported to the molding machine.
When the multilayer molded body is a multilayer preform, it is molded by, for example, a co-injection molding method or a sequential injection molding method described in JP-A-8-253222, or a sandwich molding method of Twin Shot. Is possible.

  The multilayer molded body of the present invention, for example, an injection molding apparatus that stores a melt of the thermoplastic polyester (A) from a melt polycondensation reactor, and then intermittently supplies the hot runner nozzle for the multilayer molded body; Molding using a co-injection molding machine equipped with an injection molding apparatus that melts the solid-phase polymerized thermoplastic polyester (B) and then intermittently supplies it to another flow path of the hot runner nozzle for multilayer molded article Is possible.

That is, the thermoplastic polyester (A) melt is provided with a storage tank such as an accumulator between the melt transportation means and the multilayer preform co-injection molding machine, and the continuous resin flow from the extruder is temporarily accumulated. It is possible to form a multilayer molded article by intermittently supplying the stored polyester melt to a hot runner for co-injection molding.
The resin temperature at the time of injection molding is 260 to 300 ° C, preferably 260 ° C to 280 ° C.

When the multilayer stretched molded product of the present invention is a bottle, the multilayer preform is heated to 90 to 120 ° C. and then biaxially stretched.
In the case of a heat-resistant bottle or heat-resistant pressure bottle, the mouth portion of the multilayer preform can be thermally crystallized. In general, the thermal crystallization of the mouth is preferably performed before, during, or after preheating the preform prior to stretch blow.
Biaxial stretch blow molding can be performed by a single-stage method or a two-stage method. The preform at the stretching temperature is stretched and stretched in the axial direction in a blow mold at a temperature of 100 to 200 ° C., and gas is blown and stretched in the circumferential direction.

  By using the multilayer preform which is the multilayer molded body of the present invention, it is possible to improve the dirt of the blow molding die, and thus to obtain a heat-resistant stretched bottle with excellent transparency. In addition, since mold contamination is improved, productivity is improved and economical production becomes possible.

[Amorphous carbon deposition]
Furthermore, since the amorphous carbon vapor deposition layer is laminated on the inner surface of the multilayer bottle obtained from the multilayer preform, the gas barrier property is improved, and further, the transfer of the acetaldehyde from the PET to the content is remarkably reduced. Flavor improves. As a method for vapor deposition of amorphous carbon, for example, vapor deposition can be performed by the method described in JP-A-8-53117 and JP-A-7-41579.

The “amorphous carbon deposition film” as used in the present invention refers to a physical vapor phase synthesis method (PVD) such as an ion beam sputtering method, a low pressure chemical vapor phase synthesis method (CVD), or a plasma CVD method using various raw materials. It is preferable that they are deposited on the wall surface of the container. Specifically, carbonaceous films such as diamond-like carbon film, modified carbon film and titanium oxide film, silicon oxide film, siliconized carbon film and silicon nitride film, aluminum oxide, aluminum oxide-silicon film, and mixed films thereof. Inorganic coatings and the like, and particularly preferred inorganic coatings are carbonaceous coatings such as diamond-like carbon coating and modified carbon coating. For these inorganic coatings, the technology of inorganic coatings used for improving the gas barrier properties of films and plastic bottles can be applied (for example, JP-A-8-53116 and JP-A-7-41579).

These particularly preferable amorphous carbon vapor-deposited films are aromatic hydrocarbons such as graphite, benzene and toluene, fluorinated aliphatic hydrocarbons such as monofluoroethane, difluoroethane, and mono-trifluoropropane, monofluorobenzene, and p-fluoro. Fluorinated aromatic hydrocarbons such as benzene, p-fluorotoluene (FC ₆ H ₄ CH ₃ ), mixtures of hydrocarbons and fluorine-containing hydrocarbons, hydrocarbons and fluorinated hydrocarbons (eg hexafluoroethane, perfluoropropane , Hexafluorobenzene, perfluorotoluene, etc.) is a carbonaceous film deposited on the vessel wall surface by PVD, CVD or plasma CVD, etc. from raw materials such as diamond-like carbon, hydrogenated amorphous carbon, modified Means a film of a substance called carbon That (hereinafter referred to as DLC).

The film thickness of the inorganic coating of the present invention is preferably in the range of 0.001 to 100 μm, more preferably 0.01 μm or more, further preferably 0.05 μm or more, and more preferably 50 μm or less, particularly preferably 10 μm or less. It is. When it exceeds 100 μm, the impact resistance tends to decrease, and when it is less than 0.001 μm, the barrier property tends to decrease.
The inorganic coating of the present invention may be a single layer or a multilayer. For example, a DLC film can be formed from hydrocarbons by CVD, and a modified carbon film can be formed thereon using a mixed gas of hydrocarbon and nitrogen, etc. Good. Further, a coating layer, a multilayer, or a lubricant layer may be formed on the surface of the inorganic coating to prevent the inorganic coating from peeling off.

  The layer structure of the multilayer molded body of the present invention is determined according to the use and required characteristics of the multilayer container obtained from this. For example, when biaxially stretched into a heat-resistant three-layer stretch container, it is preferable to use the thermoplastic polyester (B) for the outer layer or the inner layer and the thermoplastic polyester (A) for the intermediate layer. .

In this case, the cyclic trimer content in the outermost layer is 8000 ppm or less, preferably 5000 ppm or less, and more preferably 4000 ppm or less. Further, the content of acetaldehyde in the innermost layer is 30 ppm or less, preferably 20 ppm or less, more preferably 15 ppm or less, and most preferably 10 ppm or less.
It is necessary to determine the properties required for the thermoplastic polyester (A) melt depending on the layer structure of the multilayer molded body, the thickness of each layer, or the use.
The multilayer molded body of the present invention can be molded using a multilayer extrusion molding machine, a multilayer compression molding machine, a multilayer hollow molding machine, etc., in addition to the injection molding machine.

The thermoplastic polyester (A) and the thermoplastic polyester (B) used in the present invention include a colorant, a pigment, an ultraviolet absorber, a heat stabilizer, an antioxidant, an antistatic agent, a lubricant, a core as necessary. An agent, a release agent, an infrared absorber and the like can be added within a range not impairing the object of the present invention.
The multilayer molded body of the present invention is used for containers such as hollow containers, sheet-like objects, tray-like objects, cups, containers for filling beverages and foods, electric wires, coating materials such as metal plates, or fibrous materials. it can.

The present invention will be further described by the following examples, but the present invention is not limited to these examples.
Measurements in the examples were performed as follows.

(1) Intrinsic viscosity (IV)
It calculated | required from the solution viscosity at 30 degreeC in a 1,1,2,2-tetrachloroethane / phenol (2: 3 weight ratio) mixed solvent.

(2) Acetaldehyde content of polyester (hereinafter referred to as “AA”)
Sample / distilled water = 0.2 to 1 g / 2 cc of glass ampoule substituted with nitrogen was sealed and subjected to extraction treatment at 160 ° C for 2 hours. After cooling, acetaldehyde in the extract was subjected to high-sensitivity gas chromatography. The concentration was measured by chromatography and the concentration was expressed in ppm. The said operation is repeated 5 times and let the average value be AA content.
The sample of each layer to be used for measurement is collected by scraping from the molded body, but if isolation is difficult, the resin injected from the molding machine of each layer to the outside of the mold may be used as the sample. (3) The same applies to the subsequent analysis.

(3) Content of polyester cyclic trimer (hereinafter referred to as “CT”)
300 mg of a sample is dissolved in 3 ml of a hexafluoroisopropanol / chloroform mixed solution (volume ratio = 2/3), and further diluted with 30 ml of chloroform. To this is added 15 ml of methanol to precipitate the polymer, followed by filtration. The filtrate was evaporated to dryness, brought to a constant volume with 10 ml of dimethylformamide, and the cyclic trimer was quantified by high performance liquid chromatography. The said operation is repeated 5 times and let the average value be CT content.

(4) Diethylene glycol content of polyester (hereinafter referred to as [DEG content])
Decomposition with methanol, the amount of DEG was quantified by gas chromatography, and expressed as a ratio (mol%) to the total glycol components.

(5) Color b value of polyester and molded article Crystallized polyester and molded article were measured according to Tokyo Denshoku color difference meter TC-1500MC-88 JIS-Z8722 (Hunter color difference). A sample cut into a chip or a chip of about 2 mm square was placed in a glass cell up to the eighth minute. After shaking the cell lightly and packing it closely, resin was added until the lid was made, and the lid was capped. A cell filled with resin was placed on a sample stage and measured. Each time the cell was measured, the cell was rotated about 120 degrees and measured three times, that is, 120 degrees in three directions, and the average was obtained.
The preform was measured on a sample obtained by cutting the preform vertically.

(6) Measurement of Fine Content About 0.5 kg of resin, sieve (A) with a mesh size of 5.6 mm according to JIS-Z8801, and sieve with a mesh size of 1.7 mm (diameter) 20 cm) (B) was placed on a sieve combined in two stages, and sieved at 1800 rpm for 1 minute with a swing type sieve shaker SNF-7 manufactured by Terraoka. This operation was repeated and a total of 20 kg of resin was sieved. However, when the fine content is small, the amount of the sample is appropriately changed.
The fine sieved under the sieve (B) is washed with a 0.1% aqueous cationic surfactant solution, then washed with ion-exchanged water, and then filtered through a G1 glass filter manufactured by Iwaki Glass Co., Ltd. collected. These were dried together with a glass filter in a dryer at 100 ° C. for 2 hours, then cooled and weighed. Again, the same operations of washing and drying with ion-exchanged water were repeated to confirm that the weight became constant, and the weight of the glass filter was subtracted from this weight to obtain the fine weight. The fine content is the fine weight / the total resin weight that has been sieved.

(7) Thickness of the deposited layer Cut the shoulder and body of the multilayer bottle after deposition, cut the cross section with a microtome, measure the thickness of the deposited layer with a transmission electron microscope, The average value was taken as the thickness of the deposited layer.

(8) Oxygen permeation amount (cc / one container / 24 hr / atm)
The permeation amount per 1000 cc bottle was measured at 30 ° C. and 80% RH with an oxygen permeation meter OX-TRAN100 manufactured by Modern Controls.

(9) Sensory test a) Non-heat-resistant hollow molded body: After boiling distilled water is cooled to 50 ° C., it is placed in the hollow molded body and held for 30 minutes after sealing, and then left at 50 ° C. for 10 days. Odor tests were conducted. Use distilled water as a blank for comparison. The sensory test was carried out by 10 panelists according to the following criteria, and the average values were compared.
b) Heat-resistant hollow molded article: Distilled water boiled in the hollow molded article was held for 30 minutes after sealing and then left at 50 ° C. for 5 days. After opening, flavor and odor were tested in the same manner as described above.
(Evaluation criteria)
◎: Feel no strange taste or smell ○: Feel a slight difference from the blank △: Feel a difference from the blank ×: Feel a considerable difference from the blank XX: Feel a very large difference from the blank

[Example 1]
Melt (PET-A) from continuous melt polycondensation reactor (PET for intermediate layer) and solid state polymerized PET (PET-B) chip from continuous melt polycondensation-solid phase reactor (PET for inner and outer layers) A multilayer preform having a three-layer structure was molded by a multilayer molding machine that can be molded using
(PET-B)
High purity terephthalic acid and ethyl glycol were continuously supplied to the first esterification reactor containing the reactants in advance, and the reaction was carried out with stirring at about 250 ° C. and 150 KPa for an average residence time of 3 hours. Further, the ethylene glycol solution of germanium dioxide and the ethylene glycol solution of phosphoric acid were continuously fed separately to the first esterification reactor. This reaction product was sent to the second esterification reactor, and the reaction was carried out with stirring at about 260 ° C. and 110 KPa to a predetermined reactivity. The esterification reaction product is continuously sent to the first polycondensation reactor and stirred for about 1 hour at about 265 ° C. and 25 torr, then stirred for about 2 hours at about 265 ° C. and 3 torr for 1 hour. Further, polycondensation was performed at about 275 ° C. and 0.5 to 1 torr with stirring in the third polycondensation reactor. The obtained PET resin had an intrinsic viscosity (IV) of 0.56 dl / g and a DEG content of 2.6 mol%.
The cooling water at the time of chip formation is ion-exchanged water having a sodium content of 0.1 ppm, a calcium content of about 0.1 ppm, a magnesium content of about 0.06 ppm, and a silicon content of about 0.7 ppm. Using.
After fine removal of this resin, it was subsequently crystallized at about 155 ° C. in a nitrogen atmosphere, further preheated to about 200 ° C. in a nitrogen atmosphere, and then sent to a continuous solid-phase polymerization reactor for solid phase polymerization at about 207 ° C. in a nitrogen atmosphere. . After the solid-phase polymerization, the fine particles were removed by continuous treatment in the sieving step and the fine removal step.
The obtained PET has an intrinsic viscosity of 0.75 dl / g, an acetaldehyde (AA) content of 3.2 ppm, a cyclic trimer content of 0.35 wt%, a color b of 0.8, and a fine content of about It was 50 ppm. The residual Ge content was 45 ppm, and the residual P content was 30 ppm.
This is dried in a vacuum dryer and then supplied to the inner and outer layer injection molding machine of the multilayer molding machine.

(PET-A)
Except for changing the addition amount of the polycondensation catalyst and changing the polycondensation time in the final reactor, the melt polycondensation reaction was carried out in the same manner as PET-B, the limiting viscosity was 0.75 dl / g, and the DEG content was A melt having 2.6 mol%, an acetaldehyde (AA) content of 60 ppm, a cyclic trimer content of 1.05 wt%, and a color b of 1.0 was obtained, and this was passed through an extruder with a vent. After deaeration treatment, it was stored in a storage tank, and a multilayer preform was molded together with the PET-B by the multilayer injection molding machine connected thereto.

The intrinsic viscosity of the inner layer and outer layer of the multilayer preform are both 0.74 dl / g, and the cyclic trimer content of the inner layer and outer layer is as low as 0.37% by weight and 0.38% by weight, respectively. The AA contents of the inner layer and the outer layer were as low as 12 pm and 11 ppm, respectively. The intrinsic viscosity and acetaldehyde content of the intermediate layer were 0.75 dl / g and 22 ppm, respectively. The preform color b was 1.1. The residual Ge content of the PET-A layer was 47 ppm, and the residual P content was 31 ppm.
Samples for measurement such as inner and outer layers were shaved from the inner and outer layers of the preform.
Further, even during continuous molding, the accumulation of oligomers including cyclic trimers in the vent portion of the mold was small, and continuous production was possible. 500 bottles were continuously molded, but there was no problem with the transparency of the bottle.

The mouth portion of the resulting multilayer preform was crystallized by infrared heating, then biaxially stretched and blown using a LB-01E molding machine manufactured by CORPOPLAST, and then approximately about 150 ° C. in a mold set. A heat-resistant bottle was formed by heat fixing for 30 seconds, housed in the external electrode 12 of the vapor deposition apparatus (FIG. 1), and fixed. Next, after the vacuum pump is activated and the inside of the external electrode 12 is evacuated to 10 ⁻⁴ torr or less (back pressure), as a pretreatment, argon is plastic so that the pressure becomes 0.04 torr at a flow rate of 30 ml / min. The container was introduced into the container, and 300 W of Rf power was applied to plasma-treat the inner surface of the container. Thereafter, a bottle in which argon is used as an auxiliary gas, n-hexane is introduced into the container as a source gas, and the inner surface of the container is uniformly coated with DLC has a thickness of 1900 mm and an oxygen barrier property of 0.02 cc / A very good result was obtained with one container, 24 hr.

[Example 2]
A test was conducted in the same manner as in Example 1 except that an ethylene glycol solution of antimony trioxide and an ethylene glycol solution of cobalt acetate were used as the polycondensation catalyst to obtain a multilayer preform.
(PET-B)
The obtained PET had an intrinsic viscosity of 0.75 dl / g, a DEG content of 3.0 mol%, an acetaldehyde (AA) content of 3.8 ppm, a cyclic trimer content of 0.35 wt%, a color b 0.6 and the fine content was about 50 ppm. The residual Sb content was 200 ppm, the residual Co content was 5 ppm, and the residual P content was 10 ppm.

(PET-A)
Melting with an intrinsic viscosity of 0.75 dl / g, a DEG content of 3.0 mol%, an acetaldehyde (AA) content of 65 ppm, a cyclic trimer content of 1.03 wt%, and a color b of 0.8 I got a thing.
The intrinsic viscosity of the inner layer and outer layer of the multilayer preform are both 0.74 dl / g, and the cyclic trimer content of the inner layer and outer layer is as low as 0.39 wt% and 0.38 wt%, respectively. The AA contents of the inner layer and the outer layer were as low as 13 ppm and 14 ppm, respectively. The intrinsic viscosity and acetaldehyde content of the intermediate layer were 0.76 dl / g and 25 ppm, respectively. The measurement sample was scraped from the preform inner and outer layers. The preform color b was 0.9. The residual Sb content of the PET-A layer was 210 ppm, the residual Co content was 5 ppm, and the residual P content was 10 ppm.
Further, even during continuous molding, the accumulation of oligomers including cyclic trimers in the vent portion of the mold was small, and continuous production was possible.
500 pieces were continuously formed in the same manner as in Example 1, but there was no problem with the transparency of the bottle. When this multi-layer bottle was vapor-deposited in the same manner as in Example 1, the thickness of the vapor-deposited layer was 2000 mm, the oxygen barrier property was 0.02 cc / one container · 24 hr · atm, and the sensory evaluation was also very good. was gotten.

[Comparative Example 1]
Using only the PET-A of Example 1, a single layer preform was molded using an injection molding machine for molding a single layer preform.
The cyclic trimer content of the preform was as high as 1.1% by weight, and the AA content was as high as 100 ppm, which was a problem.
The mold vent was clogged frequently, and was forced to stop for cleaning, making it difficult to produce economically.
Further, when a heat-resistant bottle was molded in the same manner as in Example 1, except for immediately after molding, the transparency was poor, the oxygen barrier property was 0.58 cc / one container · 24 hr · atm, and the sensory evaluation was poor with ×. It was.

  The present invention has a low content of cyclic trimer and acetaldehyde in the outer layer from a melt-polycondensed thermoplastic polyester melt and a solid-phase-polymerized thermoplastic polyester, transparency and moldability, gas barrier Provided are a multilayer molded body capable of forming a multilayer stretch molded body having excellent properties and flavor properties, and a method for producing the multilayer molded body.

The conceptual diagram of a vapor deposition apparatus.

Explanation of symbols

11: Insulating plate 11A: Groove 12: External electrode 14: High frequency power supply 15: Exhaust pipe 16: Internal electrode 16A: Blowing hole 17: Source gas supply pipe 20: Container 20A: Port 21A: External space 21B: Internal space

Claims (10)

A multilayer molded body comprising at least a thermoplastic polyester (A) layer obtained from the melt after the melt polycondensation reaction and a thermoplastic polyester (B) layer having a cyclic trimer content of 8000 ppm or less, and the contents A multilayer molded article, wherein an amorphous carbon vapor deposition layer is laminated on a contact surface. The multilayer molded body according to claim 1, wherein the layer structure is three or more layers, the thermoplastic polyester (B) layer is an outermost layer, and the amorphous carbon deposition layer is an innermost layer. The multilayer molded article according to any one of claims 1 and 2, wherein the content of the thermoplastic polyester (A) layer is 30 to 99.5 wt%. The multilayer molded article according to any one of claims 1 to 3, wherein the thermoplastic polyester (B) has an intrinsic viscosity of 0.50 to 1.2 dl / g and an acetaldehyde content of 20 ppm or less. The multilayer molded article according to any one of claims 1 to 4, wherein the intrinsic viscosity of the thermoplastic polyester (A) is 0.60 to 0.90 dl / g. The multilayer molded article according to any one of claims 1 to 5, wherein at least one layer of the thermoplastic polyester (A) layer or the thermoplastic polyester (B) layer contains an acetaldehyde reducing agent. The multilayer molded article according to any one of claims 1 to 6, wherein the multilayer molded article is a bottomed multilayer preform. The multilayer molded body according to any one of claims 1 to 6, wherein the multilayer molded body is a sheet-like material. A multilayer stretched molded product obtained by stretching the multilayered molded product according to any one of claims 1 to 8 in at least one direction before laminating an amorphous carbon vapor deposition layer. Contents after molding a multilayer molded body from the melt of the thermoplastic polyester (A) from the polycondensation reactor after the melt polycondensation reaction and the thermoplastic polyester (B) having a cyclic trimer content of 8000 ppm or less The method for producing a multilayer molded article according to any one of claims 1 to 8, wherein an amorphous carbon vapor deposition layer is laminated on the object contact surface.

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