JPH0985795A - Manufacture of polyester sheet for draw forming - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyester sheet having improved heat resistance, hot water resistance, aromaticity, forming property, and drawdown proofing property as well as a good alcohol resistance, thermal stability, gas barrier property, ultraviolet rays interruption property, and recycling property. SOLUTION: Placed in an extrusion machine with a dies connected is 3-98wt.% polyethylenenaphthalenedicarboxylate having a limiting viscosity of 0.5-1.3dl/g and 2-97wt.% polyethylene terephthalate having a limiting viscosity of 0.5-1.5dl/g, and they are extruded into a sheet in conditions such that resin temperature A within the extrusion machine is kept at 270-330 deg.C and resin temperature B from the screw tip end to the dies outlet of the extruding machine is maintained lower than resin temperature A by 5 deg.C or higher and at 220-300 deg.C. Thus this is a manufacture of draw forming polyester sheet with a glass transition temperature of 80 deg.C or higher and a content of acetaldehyde of 0.005wt.% or lower.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention is excellent in heat resistance, hot water resistance, alcohol resistance, aroma retention, thermal stability, moldability, drawdown resistance, gas barrier property, ultraviolet blocking property, recyclability and the like. The present invention relates to a method for manufacturing a polyester sheet.

[0002]

2. Description of the Related Art Polyethylene terephthalate (hereinafter P)
(Sometimes called ET) means mechanical strength, chemical stability,
Since it is excellent in transparency, hygiene, recyclability, etc., and is lightweight and inexpensive, it is widely used as various sheets and containers for packaging materials. In particular, in recent years, from the viewpoint of waste disposal problems and environmental protection, the development of applications such as extruded sheets and squeezed containers, which have been frequently used for polyvinyl chloride and polystyrene, has been remarkable. PET like this
For example, in the case of a squeezed container, extruding a sheet with an extruder,
Then, it is generally manufactured by drawing. However, the conventional PET sheet has a large drawdown when it is preheated at the time of drawing, and especially, the homo P
In the case of ET, there is a problem that the sheet may be crystallized during preheating and may not be molded. Also,
A conventional transparent squeeze container formed by drawing a PET sheet is used in an unstretched state or a low stretched state without being subjected to a crystallization treatment, so that it does not necessarily have sufficient heat deformation resistance and hot water resistance. This is not true, especially when the contents are hot, for example, when hot water treatment (retort treatment) or hot water filling (hot fill) for sterilization is performed, or when the contents are heated (for sake When used in (such as smoke), the volume tends to change due to contraction of the sides and corners of the molding container and deformation such as warpage and swelling on flat parts such as side and bottom surfaces. There was a problem such as.

On the other hand, polyethylene naphthalene dicarboxylate (hereinafter sometimes referred to as PEN) is PET.
Although it is superior in heat resistance, gas barrier property and ultraviolet ray blocking property, it has inferior impact resistance, high melt viscosity and high price as compared with PET having the same limiting viscosity. Therefore, when trying to obtain a packaging material made of homo-PEN having sufficient impact resistance, it is necessary to use PEN having a high intrinsic viscosity. In this case, the moldability at the time of sheet molding is poor due to the high melt viscosity. However, there were problems such as thermal deterioration of PEN and a large amount of by-product of acetaldehyde. Therefore, PE
In reality, it is rare to use N alone as a packaging material. Also, PEN is usually recycled by adding it to PET, but especially in the case of homo PEN, PET is added.
However, there is a problem in that when added to the above, it may cause phase separation and whitening. Furthermore, since amorphous PET or PEN usually contains a large amount of acetaldehyde produced as a by-product during polymerization or sheet formation, it cannot be said that the fragrance-retaining property is sufficient, and the content is particularly high temperature. Occasionally, there is a problem that acetaldehyde is eluted and a nasty smell (acetaldehyde odor) is added to the contents.

On the other hand, as a processing method for improving the heat resistance of the drawn product, a sheet is once stretched and then heat-processed (JP-A-50-21051 and JP-A-5-51).
7-53316, Japanese Patent Publication No. 1-28850,
U.S. Pat. No. 4,388,356, JP-A-58-674.
No. 11) has been proposed, but since a sheet stretching operation is required, there is a problem that the processing cost is higher than that of the conventional processing method and the productivity is further reduced. Also, after heating the sheet to a crystallization temperature or higher to make the hanging length of the sheet 5 to 50% of the diameter of the mold opening,
Method of molding with a mold of 70 ° C or less (Japanese Patent Publication No. 6-49
No. 334) is also proposed. Although this method has higher productivity than the method requiring the above-described stretching operation, since the sheet is heated to the crystallization temperature or higher, the PET forming the sheet is easily crystallized, and in a continuous thermoforming for a long time. However, as compared with the conventional method, there is a problem that the incidence of defective molding becomes higher. Further, a method of blending or laminating PET with a resin having a high heat resistance, such as a polycarbonate resin, has been attempted, but the moldability is lowered, or coloring occurs during molding,
There are problems that the gas barrier property is lowered and the productivity is lowered as compared with the conventional one.

As a method for reducing the acetaldehyde content of the polyester melt, a method of carrying out melt polymerization with a formulation having a small amount of acetaldehyde by-product, or a method of reducing acetaldehyde by-produced at the time of molding, for example, the raw material polyester is water, Method of deactivating the polycondensation catalyst contained by contacting with steam or steam-containing gas (JP-A-3-047830, JP-A-4-211424), reduced pressure when extruding with a twin-screw extruder with a vent port Method for devolatilization with a system (JP-A-6-315959)
Etc. are known. However, the effect of reducing the acetaldehyde content by these methods is not always sufficient, and there is also a problem that it takes time and cost if a special treatment or apparatus is required. Furthermore, PET
In addition, a method of blending a polyester resin such as PEN or polyarylate resin having a glass transition temperature and a density within a specific range (JP-A-6-328583) has been proposed, but this method has impact resistance. The purpose is to reduce the decrease over time, and since the sheet is molded with a normal prescription using substantially amorphous pellets, the amount of acetaldehyde is large, and the aroma retention of the resulting sheet or molded product is insufficient. There was a drawback that was. In addition to this, many reports have been made on polyester sheets obtained by blending PEN and PET. However, conventional PET
The drawability of the polyester is improved as compared to the sheet-made sheet, and a draw-formed body having improved heat-resistant deformation and aroma retention can be provided, and a specific polyester draw-forming sheet and its specific manufacturing method are known. There wasn't.

[0006]

The object of the present invention is to improve heat resistance, hot water resistance, aroma retention, moldability, drawdown resistance, and alcohol resistance as compared with conventional PET sheets. Another object of the present invention is to provide a polyester sheet for drawing which is excellent in heat stability, gas barrier property, ultraviolet blocking property, recyclability and the like.

[0007]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors have found that a polyester sheet formed by blending PEN and PET in a specific ratio in a specific method is The inventors have found that the above problems are fully satisfied, and have completed the present invention. That is, the gist of the present invention is 3 to 98% by weight of polyethylene naphthalene dicarboxylate having an intrinsic viscosity of 0.5 to 1.3 dl / g, and polyethylene terephthalate 2 having an intrinsic viscosity of 0.5 to 1.5 dl / g. 97% by weight is charged into an extruder to which a die is connected, the resin temperature A in the cylinder of the extruder is 270 to 330 ° C, and the resin temperature B from the screw tip of the extruder to the die outlet is the resin temperature. A polyester sheet for squeeze molding having a glass transition temperature of 80 ° C or higher and an acetaldehyde content of 0.005% by weight or less, which is extruded into a sheet at 5 ° C or more lower than A and 220 to 300 ° C. It depends on the manufacturing method.

Hereinafter, the present invention will be described in detail. The polyester sheet for drawing used as the object of the present invention is PEN3.
-98% by weight, preferably 5-80% by weight, more preferably 7-50% by weight, particularly preferably 8-30% by weight
And 97 to 2% by weight of PET, preferably 95 to 20% by weight, more preferably 93 to 50% by weight, and particularly preferably 92 to 70% by weight. If the PEN ratio is less than 3% by weight, the heat resistance, hot water resistance and drawdown resistance of the obtained sheet are insufficient, which is not preferable.
When the PEN ratio exceeds 98% by weight, the impact resistance of the obtained sheet is insufficient and phase separation is likely to occur during recycling with PET, which is not preferable. Further, the polyester sheet for draw forming of the present invention is, within a range that does not deviate from the constitutional requirements of the present invention, an end portion (a trimming due to trimming) of a sheet that occurs during sheet forming or draw forming, and a surplus portion after punching ( A skeleton) or the like may be contained as a raw material. When using these mimi and skeletons, it is desirable to use them in a range of 50% by weight or less, more preferably 40% by weight or less based on the total raw materials.

Further, in the present invention, an antioxidant such as a hindered phenol-based, phosphorus-based, or thioether-based antioxidant, a coloring agent such as titanium dioxide, a nucleating agent such as talc, etc., within a range not departing from the constitutional requirements of the present invention, Lubricants such as calcium carbonate and silica, mold release agents, flame retardants, heat stabilizers,
Additives such as a hydrolysis resistance agent, an antistatic agent, a hard coating agent, an ultraviolet absorber, a light resistance stabilizer, and a fluorescent brightening agent may be appropriately contained in the obtained sheet. These additives may be added as it is when the sheet of the present invention is molded, or may be added in a masterbatch state,
You may add at the time of manufacture of raw material polyester. Further, these additives may be applied to the surface treatment of the sheet by a method such as coating or laminating. The drawing-use polyester sheet that can be produced by the present invention has a glass transition temperature (hereinafter, referred to as Tg) measured by a differential scanning calorimeter (hereinafter, referred to as DSC) of 80 ° C. or higher, preferably 82 ° C. or higher, and further preferably. It is 83 ° C or higher. Tg
Is less than 80 ° C., the improvement in heat-resistant deformation of the obtained draw-formed body is not substantially recognized as compared with the case where a conventional PET sheet is used, which is not preferable.

The Tg was measured by using a stainless razor blade to cut one piece (weight 5.0 mg) cut out from the sample without shearing as much as possible, and enclosing it in an aluminum pan under a nitrogen atmosphere. Temperature rising rate from room temperature to 20 ° C /
It is carried out by a measuring operation in which the temperature is raised to 300 ° C. in minutes. Tg
Is obtained from the behavior of the specific heat change due to the glass transition of the calorific curve, and specifically, is the temperature at the intersection of the tangent line at the midpoint of the specific heat change due to the glass transition and the tangent line before the specific heat change. The acetaldehyde content of the draw-forming polyester sheet that can be produced by the present invention is 0.005% by weight.
The amount is preferably 0.003% by weight or less, more preferably 0.0015% by weight or less. When the acetaldehyde content is more than 0.005% by weight, when the drawn product obtained from the sheet of the present invention is used as a packaging material that comes into direct contact with foods, it gives an off-flavor to the contents. In some cases, it is not preferable. The acetaldehyde content was measured by subdividing 5 g of the sample sheet, enclosing it in a micro bomb together with water, and immersing it in an oil bath at 160 ° C for 2 hours to extract hot water from the sheet, and then use it as a standard reagent. It is performed by adding isobutyl alcohol and quantifying by gas chromatography.

Conventionally, as a method of reducing the acetaldehyde content of a polyester melt, a method of reducing the amount of acetaldehyde in the raw material polyester, for example, a method of carrying out melt polymerization with a formulation having a small amount of acetaldehyde by-product, and drying a melt-polymerized product Also known are a crystallization method, a subsequent solid phase polymerization method, a method in which a raw polyester is brought into contact with water, steam, or a steam-containing gas to deactivate the polycondensation catalyst contained therein. The combined use of such a method is preferable because the acetaldehyde content in the sheet can be further reduced. The transparency of the polyester sheet for drawing obtained by the present invention is described by the haze value measured in the thickness direction of the sheet. The haze value of the sheet of the present invention is usually 6% or less, preferably 4% or less, more preferably 3%.
% Or less, particularly preferably 2% or less. When the haze value is within this range, PEN and PET are sufficiently compatible with each other, so that recycling is easy and improvement in moldability at the time of draw molding is observed, which is preferable. The haze value is measured by cutting a sample sheet into a 5 cm × 5 cm square and using a HGM-2DP type direct reading haze computer manufactured by Suga Test Instruments Co., Ltd.

The thickness of the polyester sheet for drawing obtained by the present invention is usually 0.1 to 5 mm. The optimum thickness of the sheet used for draw forming is the design of the draw forming body, that is, the size and thickness of the draw forming body to be manufactured,
Although it varies depending on the shape, weight, draw ratio, mechanical properties, etc., generally, as a raw sheet for a draw-molded body used as a packaging material or the like, the thickness is 0.1 to 5 mm, preferably 0.15. A sheet having a thickness of -3 mm, more preferably 0.2-2 mm is used. The sheet obtained according to the present invention is capable of producing a thicker squeeze molded article with good moldability when producing a squeeze molded article having the same shape except for the thickness as compared with the conventional PET transparent sheet. It has characteristics. Further, the sheet obtained by the present invention,
Even if the thickness is smaller than that of the conventional PET transparent sheet, it has a feature that a squeeze molded article having higher heat deformation resistance than the case of using the conventional PET transparent sheet can be manufactured. Therefore, when designing a draw-formed body, it is not necessary to increase the thickness only for the purpose of improving the heat deformation resistance, so that the weight reduction,
It is possible to save resources and reduce costs.

Next, the raw material polyesters (PEN and PET) used in the present invention will be described in detail. First,
In the present invention, PEN is a polyester containing naphthalenedicarboxylic acid and ethylene glycol as main components, and PET is a polyester containing terephthalic acid and ethylene glycol as main components. Further, regarding naphthalenedicarboxylic acid, 2,6-, 2,7-, 1,4-,
Examples of the naphthalenedicarboxylic acid include 1,5-, 1,8-, and 2,3-, but any naphthalenedicarboxylic acid may be used, and these naphthalenedicarboxylic acids may be used alone. Or two or more of them may be used in combination. Among these naphthalenedicarboxylic acids, 2,6- and 2,7-naphthalenedicarboxylic acids are preferable, and 2,6-naphthalenedicarboxylic acids are more preferable.

The raw materials PEN and PET are respectively
You may contain a copolymerization component in the range which does not impair the effect of this invention. Examples of the copolymerizable component that can be contained include dicarboxylic acid components such as phthalic acid, isophthalic acid, 4,4′-diphenylsulfonedicarboxylic acid, and 4,4′-biphenyldicarboxylic acid as dicarboxylic acid components. Alicyclic dicarboxylic acids such as dicarboxylic acid and 1,4-cyclohexanedicarboxylic acid, aliphatic dicarboxylic acids having an aromatic ring such as 1,3-phenylenedioxydiacetic acid, succinic acid, adipic acid, sebacic acid, diglycol Examples thereof include aliphatic dicarboxylic acids such as acids. Incidentally, terephthalic acid can be mentioned as PEN and naphthalenedicarboxylic acid can be mentioned as PET as PET. Further, as a diol component, diethylene glycol, 1,2-propanediol, 1,3-
Propanediol, 1,4-butanediol, 1,6-
Hexanediol, neopentyl glycol, aliphatic diols such as 2-butyl-2-ethyl-1,3-propanediol, alicyclic glycols such as 1,4-cyclohexanedimethanol, and fragrances such as bisphenol A and bisphenol S. Examples thereof include group diols and condensation products thereof with aliphatic diols. Furthermore, examples of the oxycarboxylic acid component include p-hydroxybenzoic acid and glycolic acid. The copolymerization ratio of these bifunctional components is 2 for both PEN and PET.
It is desirable that the amount is 0 mol% or less, preferably 15 mol% or less, more preferably 10 mol% or less, and particularly preferably 5 mol% or less. When the copolymerization ratio is in this range, the crystallinity of the raw material polyester is high and solid phase polymerization is possible, which is more preferable. Here, the copolymerization ratio means PE
In the case of T, the ratio of the dicarboxylic acid component other than terephthalic acid to the total dicarboxylic acid component (in the case of PEN, the ratio of components other than naphthalene dicarboxylic acid) and the ratio of the diol components other than ethylene glycol and diethylene glycol to the total diol component are calculated. It's a sum.

Regarding the copolymerization ratio of diethylene glycol, the ratio of the raw material polyester to the total diol components is 5 mol% or less, more preferably 4 mol% or less, and particularly 3
It is desirable that the content is mol% or less. When the copolymerization ratio of diethylene glycol is within this range, the thermal stability of the sheet obtained by the present invention and the heat-induced deformation resistance of the molded product obtained by molding the sheet are high, which is more preferable. In addition, a small amount of a trifunctional or higher polyfunctional component may be copolymerized within a range that does not impair the effects of the present invention. As the trifunctional or higher polyfunctional component, a known compound conventionally used in PET may be used, for example, trimellitic acid, trimesic acid, a polyvalent carboxyl component such as pyromellitic acid, trimethylolethane, Examples thereof include polyhydric hydroxy components such as trimethylolpropane, glycerin and pentaerythritol, and glycidyl ether components of aromatic dihydroxy compounds such as bisphenol A diglycidyl ether and bisphenol S diglycidyl ether. These trifunctional or higher polyfunctional components are not required to be used as essential components, but when they are used, a range in which gelation does not substantially progress, specifically, the resulting sheet is constituted. The amount is usually 1.0 mol% or less, preferably 0.6 mol% or less, based on the total monomer unit components. Since the polyfunctional component is copolymerized in a small amount, the degree of drawdown of the sheet tends to be smaller when the sheet is drawn.

Further, within the range that does not impair the effects of the present invention,
A raw material obtained by copolymerizing a small amount of a monofunctional component may be used. Examples of the monofunctional component include benzoic acid, t-butylbenzoic acid, benzoylbenzoic acid, stearic acid, benzyl alcohol and stearyl alcohol. These monofunctional components do not have to be used as essential components, but when they are used, they are usually used in an amount of 0.005 to 1.0 mol% based on the total monomer unit components constituting the obtained sheet. , Preferably 0.01-0.
It is preferably in the range of 75 mol%. Since the monofunctional component is copolymerized, the thermal stability at the time of forming the sheet is improved, and the acetaldehyde content of the sheet of the present invention can be suppressed to be smaller.

The limiting viscosity of the raw material polyester of the polyester sheet for draw-forming according to the present invention is PEN 0.5-1.
3 dl / g, preferably 0.55 to 1.1 dl / g, more preferably 0.6 to 1.0 dl / g,
PET is 0.5 to 1.5 dl / g, preferably 0.55
~ 1.3 dl / g, more preferably 0.6-1.1 d
1 / g, particularly preferably 0.65 to 1.0 dl / g. When the intrinsic viscosity of PEN and / or PET is less than 0.5 dl / g, the thickness and unevenness of the drawn product obtained by drawing may be large and it may have sufficient practical strength. It is not preferable because it does not exist. When the intrinsic viscosity of PEN exceeds 1.3 dl / g or when the intrinsic viscosity of PET exceeds 1.5 dl / g,
When the sheet is melt-molded because the melt viscosity is too high, the shearing heat generation in the molding machine becomes large, the thermal decomposition of the raw material polyester and the by-product of acetaldehyde become remarkable, and the acetaldehyde content of the obtained sheet It is not preferable because the increase is remarkable.

The measurement of the intrinsic viscosity is 0.25 g of the sample.
Was dissolved in 25 ml of a mixed solvent of phenol / 1,1,2,2-tetrachloroethane (weight ratio = 1/1), and 3
Perform at 0 ° C. The acetaldehyde content of the raw material polyester may be any as long as the sheet of the present invention can be obtained, but PEN and / or PE
The acetaldehyde content of T is 0.03% by weight or less, preferably 0.02% by weight or less, and more preferably 0.0.
1% by weight or less, more preferably 0.005% by weight or less,
Particularly preferably, it is 0.001% by weight or less. When the acetaldehyde content of the raw material polyester is within this range, it is easier to reduce the acetaldehyde content when forming the sheet, and therefore, it is more preferable. The acetaldehyde content was measured by subdividing 5 g of the raw material polyester as a sample, enclosing it in a micro-bomb with water, and immersing it in an oil bath at 160 ° C. for 2 hours to extract hot water from the raw material polyester, followed by standardization. It is performed by adding isobutyl alcohol as a reagent and quantifying by gas chromatography.

Regarding the thermal characteristics of the raw material polyester,
Any material may be used as long as the sheet of the present invention can be obtained, but it is preferable that it has crystallinity. Specifically, in the case of PEN, after heat-treating in a nitrogen atmosphere at 200 ° C. for 3 hours, 220-280 ° C., and further 230-28.
It has a melting peak (hereinafter sometimes referred to as Tm) in the range of 0 ° C., particularly 240 to 280 ° C., and in the case of PET, 1
After heat treatment for 3 hours at 80 ° C. in a nitrogen atmosphere, 200-
260 ° C, further 210-260 ° C, especially 220-
It is desirable to have Tm in the range of 260 ° C. When the raw material polyester has the above-described crystallinity, the drying treatment before molding is easy, and the acetaldehyde content in the pellets can be reduced by the crystallization treatment or the solid-state polymerization. It is more preferable because it has high moldability when the sheet is drawn.

The Tm was measured by cutting one piece (weight 5.0 mg) from the heat-treated sample with a stainless razor blade without shearing as much as possible, and cutting it into an aluminum pan. After enclosing, the measurement is performed in a nitrogen atmosphere with a TA Instruments thermal analyzer (DSC) manufactured by TA Instruments, Inc. from room temperature to 300 ° C. at a heating rate of 20 ° C./min. Tm is a temperature at which the endothermic amount per unit time becomes maximum at the endothermic peak derived from the melting of crystals during the temperature rising process.

Usually, the raw material polyester comprises a polymer skeleton such as a metal element such as manganese, cobalt, zinc, antimony, germanium or titanium derived from the catalyst used in the production thereof or a phosphorus element derived from a stabilizer. Contains one or more elements other than. The types and amounts of these contained elements are not particularly limited as long as they do not exceed the constitutional requirements of the present invention, but from the viewpoint of color tone, PEN and PET using antimony or germanium as a polycondensation catalyst are preferable. used. The above-mentioned raw material polyester of the polyester sheet for draw-forming of the present invention is produced by melt polymerization, or by subsequent drying and crystallization steps, or further by subsequent solid phase polymerization according to a conventionally known method for both. Examples of the melt polymerization method include a method in which a direct esterification reaction is performed using a dicarboxylic acid and a diol, and then a polycondensation reaction is performed by further increasing the temperature and gradually reducing the pressure, or an ester derivative using a dicarboxylic acid ester derivative diol. Examples include a method of performing an exchange reaction, and then subjecting the obtained reaction product to a polycondensation reaction.

The drying and crystallization steps can follow melt polymerization. Since the content of acetaldehyde can be reduced by subjecting the raw material PEN and / or PET used for the sheet of the present invention to crystallization treatment, the acetaldehyde content of the sheet of the present invention and its drawn product can be reduced, which is more preferable. The drying and crystallization steps are
It can be performed under reduced pressure, in an atmosphere of an inert gas such as nitrogen, or in an air atmosphere, and the temperature of the atmosphere is usually 1
20-220 degreeC. Solid phase polymerization can be carried out under reduced pressure or in an inert gas atmosphere such as nitrogen, etc., following the drying and crystallization steps, and the temperature of the atmosphere is usually 200 to
250 ° C. The crystallinity of the crystallized product obtained by these treatments can be determined by measuring the density. The densities of PEN and PET in the completely amorphous state are 1.325 g / cm ³ and 1.335 g / cm ³ , respectively.
cm ³ and the density increases with crystallization, and the densities of fully crystalline PEN and PET are 1.455 g /
It is known that it is about cm ³ and 1.407 g / cm ³ . The density of the crystallized product is 1.35 g / PEN.
cm ³ or more, further 1.36 g / cm ³ or more, particularly 1.365 g / cm ³ or more, for PET 1.36
It is preferably g / cm ³ or more, more preferably 1.37 g / cm ³ or more, and particularly preferably 1.38 g / cm ³ or more. When the density is in this range, the effect of reducing the content of acetaldehyde in the raw material by the above treatment is high, and the content of acetaldehyde in the sheet of the present invention or the drawn product thereof can be reduced, which is more preferable. Note that the density of the sample 6
g is put in an aluminum container, and it is carried out at 23 ° C. by an Acupic 1330 dry automatic densitometer.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the method for producing the polyester sheet for drawing according to the present invention will be described in detail. The polyester sheet for drawing of the present invention is conventionally PET or PE.
It can be manufactured using an extrusion cast molding machine to which a die is connected, which is used for N sheet molding. As the extruder of these extrusion cast molding machines, a single-screw or twin-screw extruder can be mentioned, but it is preferable to use a twin-screw extruder, more preferably a twin-screw extruder with a vent port. When a twin-screw extruder is used, the raw materials PEN and PET can be more easily made compatible with each other. When producing the polyester sheet for drawing according to the present invention, for example, the raw material is supplied to a hopper of a single-screw or twin-screw extruder connected to a T die through a gear pump and melted in a cylinder of the extruder. It can be manufactured by extruding a sheet form from a T-die and cooling it with a casting roll.

Any method may be used as a method of charging the raw materials, for example, a method of charging all at once from the main hopper,
There is a method of charging a part from the side feeder. Regarding the molding temperature (resin temperature), the resin temperature A in the cylinder of the extruder is 270 to 330 ° C., preferably 2
75 to 320 ° C., more preferably 280 to 310 ° C., the resin temperature B from the screw tip to the die outlet is 5 ° C. or more, preferably 10 ° C. or more, more preferably 15 ° C. or more lower than the resin temperature A and 220 to 300. ° C, preferably 230-295 ° C, more preferably 240-29
It shall be in the range of 0 ° C. In the present invention, the resin temperature A in the cylinder is the resin temperature from the center of the cylinder to the tip of the screw when the cylinder is viewed in the resin flow direction, and when there are multiple measurement points. The arithmetic mean is used. In addition, when there are a plurality of measurement points for the resin temperature B from the tip of the screw to the die outlet, the arithmetic average is taken. The resin temperature is measured with one or more thermocouples attached to the place in the extruder.
When the resin temperature A is less than 270 ° C., the melt viscosity is high, so that the extrusion amount per power of the extruder is reduced and thus the productivity is reduced, and PEN and PET are not compatible in the extruder, Moldability, recyclability, and transparency of the obtained sheet are deteriorated, which is not preferable. Further, when the resin temperature in the cylinder of the extruder exceeds 330 ° C., the raw material polyester is thermally deteriorated in the extruder and a large amount of acetaldehyde is produced as a by-product, so that the moldability and aroma retention of the obtained sheet are improved. Is reduced, which is not preferable.

If the resin temperature B is not lower than the resin temperature A by 5 ° C. or more, the amount of acetaldehyde produced as a by-product in the portion from the screw tip of the extruder to the die outlet is large, and the aroma retaining property of the obtained sheet is deteriorated, which is not preferable. . When the resin temperature B is lower than 220 ° C., the melt viscosity is high, so that the extrusion amount per power of the extruder is reduced and the productivity is reduced,
Further, when the obtained sheet has crystallinity, the crystallized resin adheres to the vicinity of the lip of the die, the surface property of the sheet decreases, extrusion becomes difficult, and clogging of the resin occurs in the die. In some cases, it is not preferable. Also,
When the resin temperature B exceeds 300 ° C., the resin deterioration product adheres to the lip portion of the die and the surface property of the sheet deteriorates, which is not preferable. The sheet extruded from the die is
It is desirable to cool rapidly so that crystallization does not proceed, and it is desirable to cool with an electrostatic contact type or touch roll type casting roll. In this case, the surface temperature of the casting roll is usually controlled to 20 to 70 ° C, preferably 25 to 60 ° C.

The extruder used for extrusion cast molding preferably has at least one, and more than two vent ports in the cylinder portion. When an extruder without a vent port is used, in order to prevent hydrolysis of the raw material polyester in the cylinder, the raw material polyester is dried to have a water content of usually 0.01% by weight or less, preferably 0.005% or less. Feed it to the hopper after making it less than weight%.
On the other hand, when an extruder having a vent port is used, the inside of the cylinder is depressurized to dry the raw material polyester in the cylinder, and therefore the raw material may be supplied without being dried, and the raw material polyester may be supplied. It is more preferable because volatile impurities such as acetaldehyde contained in the can be reduced in the cylinder. Normally the vent port is 200 mmHg or less, preferably 100 mmHg
Hereinafter, it is preferably used by connecting to a reduced pressure system of 50 mmHg or less, particularly preferably 10 mmHg or less. Further, when a vent port is used, it is preferable to use a twin-screw extruder because the efficiency in reducing volatile impurities is good. At this time, the screw of the twin-screw extruder may be a mesh type, a non-mesh type, or an incomplete mesh type.

The polyester sheet for squeeze molding produced by the present invention is usually cast on a casting roll and then trimmed at both ends of the sheet, and then wound into a roll or cut into a panel to finally obtain a sheet. can get. Both ends of the cut sheet may be recycled in addition to the raw material. When recycling,
It is desirable to use after crushing with a crusher or the like. The polyester sheet for draw forming thus obtained is a draw-formed body excellent in heat deformation resistance, hot water resistance, alcohol resistance, aroma retention, thermal stability, gas barrier property, ultraviolet blocking property, etc. with good productivity. Can be served. More specifically, by drawing the sheet of the present invention, it is less likely to cause deformation even when filled with high temperature contents than when using a conventional polyester transparent sheet. Can be manufactured. Further, since the squeeze molded article made of the sheet produced by the present invention is excellent in aroma retention, it does not add an offensive odor to the contents, and the change in odor of soft drinks, liquors, flavors, cosmetics, etc. Ideal as a packaging material that comes into direct contact with contents that do not like. Further, the sheet produced by the method of the present invention is more resistant to drawdown during drawing than the conventional polyester sheet, so that the drawn molded article can be stably formed in a high cycle.

In drawing the polyester sheet for drawing produced by the present invention, any method conventionally known as a method for drawing a polyester sheet may be used. Examples of the draw forming method include vacuum forming, pressure forming, snapback forming, revers draw forming, air slip forming, plug assist forming, and a processing method in which these are combined. Good. The drawing ratio is usually 0.01 to 10 times, preferably 0.05 to 5 times. Generally, it is desirable that the sheet temperature at the time of draw forming is such that the temperature unevenness in the thickness direction is as small as possible, and the preheating temperature of the sheet at the time of performing these draw forming is not less than the glass transition temperature and not more than 200 ° C. The glass transition temperature is preferably 180 ° C. or higher. When the preheating temperature of the sheet is within this range, the moldability of the molded product from the sheet is good, and acetaldehyde is not produced as a byproduct during preheating, which is more preferable.

The molded body obtained by drawing the sheet of the present invention is used for general packaging materials such as fruit,
Tea bags, trays and cups for packaging foods and beverages such as soft drinks, their lids, industrial trays for packaging electronic components, toothbrushes, headphones, blister packages for packaging gifts, etc. Among them, in particular, since the squeeze molded article made of the sheet of the present invention is excellent in aroma retention, soft drinks, alcohol, flavors,
It is most suitable for packaging that comes into direct contact with contents such as cosmetics that do not like odor change. Since the packaging material formed by drawing the sheet of the present invention has high heat deformation resistance and hot water resistance, especially when the contents are at a high temperature, for example, hot water treatment for sterilization (retort treatment) or hot water filling ( When used for hot filling) or for heating the contents (sake of sake etc.), the sides and corners of the molding container are less likely to shrink,
Since deformation such as warpage or swelling is unlikely to occur in a flat part such as a side surface or a bottom surface, there is an advantage that the volume is hard to change.

[0030]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, which, however, are not intended to limit the scope of the present invention. Moreover, the measuring method of the intrinsic viscosity, the measuring method of the glass transition temperature (Tg), the measuring method of the melting point (Tm), the measuring method of the acetaldehyde content, the measuring method of the haze value, and the measuring method of the density used in the present invention are , As described in the text. The moldability evaluation, heat distortion resistance test, and acetaldehyde odor sensory test used in the present invention are shown below.

(1) Evaluation of Formability The target sheet was draw-formed with a plug assist type vacuum pressure air forming machine at a draw ratio of 1.5 to produce a frustoconical cup having an internal volume of 200 ml. Regarding the goodness and badness of moldability when 100 cups are continuously molded, whether or not molding is possible, temperature range in which molding is possible (preferably molding at low temperature), reproducibility of overall shape, reproducibility of flange part, The presence or absence of vacuum hole marks (preferably not present) is used as an evaluation item, and 3
A comprehensive evaluation was made at each stage. In addition, the contents of the three-stage evaluation are:
Good moldability, Δ: Moldability is low but molding is possible, ×: Molding is not possible.

(2) Thermal deformation resistance test Demineralized water 180 at a predetermined temperature was added to the cup prepared in the above item (1).
When cc was added and the mixture was allowed to stand at room temperature for 30 minutes, the maximum temperature at which substantially no deformation was observed was defined as the heat-resistant deformation temperature. The test temperature is a temperature in steps of 2 ° C (even temperature).
And 60 ° C. to 96 ° C. In this test, the higher the heat deformation temperature, the better the heat deformation resistance. (3) Acetaldehyde odor sensory test The cup produced in (1) was charged with 180 cc of demineralized water at 60 ° C., and after cooling to 30 ° C., a sensory test was performed on the odor of the demineralized water. This test is for trained panelists 5
The five-stage evaluation of humans gave the average value as the test result. The contents of the 5-grade evaluation are 0: no odor is felt, 1: odor is slightly felt, 2: odor is weakly felt, 3: odor is felt, 4: odor is strongly felt. In this test, the lower the evaluation value, the more excellent the fragrance retention,
Those having a score of 2.5 or less are generally suitable as a food packaging material, and those having a score of less than 2 are particularly suitable for use in water, sake and the like.

[Raw materials used in the test] In the examples,
The following raw materials were used. In addition, the measured values of intrinsic viscosity, Tm, and density of these raw materials are shown in Table 1 below. (1) PEN used as a raw material: N-1: The dicarboxylic acid component is entirely naphthalene dicarboxylic acid, and the diol component is ethylene glycol 99.
Amorphous PEN N-2: N-1 crystallized PEN N-3: N-2 solid-state polymerization PEN N-4: dicarboxylic acid consisting of mol% and diethylene glycol 1 mol% All components are naphthalene dicarboxylic acid and diol component is ethylene glycol 98
Amorphous PEN N-5: N-4 solid-state polymerized PEN N-5 consisting of 2 mol% diethylene glycol and PEN N-6: dicarboxylic acid component is naphthalenedicarboxylic acid 9
Amorphous PEN consisting of 2 mol% and terephthalic acid 8 mol%, diol component consisting of 98 mol% ethylene glycol and 2 mol% diethylene glycol

(2) PET used as a raw material: T-1: PE in an amorphous state in which the dicarboxylic acid component is entirely terephthalic acid, the diol component is 98 mol% ethylene glycol, and 2 mol% diethylene glycol.
TT-2: PET obtained by crystallizing T-1 T-3: PET obtained by solid-phase polymerization of T-2 T-4: 90% by mole of terephthalic acid as a dicarboxylic acid component,
Amorphous PET T-5 consisting of 10 mol% of naphthalenedicarboxylic acid, 98 mol% of diol component and 2 mol% of diethylene glycol: dicarboxylic acid component consisting entirely of terephthalic acid, diol component consisting of ethylene glycol 92 PE in an amorphous state consisting of mol% and diethylene glycol 8 mol%
T

[0035]

[Table 1] In the above Table 1, N is 2,6-naphthalenedicarboxylic acid, T
Means terephthalic acid, EG means ethylene glycol, and DEG means diethylene glycol.

Example 1 As a raw material polyester, 15% by weight of N-1 and T-1 were used.
Was used to form a sheet. After the raw material polyester was pellet-blended, it was supplied to a 65 mmφ twin-screw extruder having a vent port connected to a decompression system of 1 mmHg and extruded from a T die to obtain a transparent sheet having a thickness of 0.6 mm. The extrusion rate was 200 kg / hour, the resin temperature during extrusion was 290 ° C. in the cylinder, 270 ° C. from the screw tip to the die outlet, and the casting roll surface temperature was 40 ° C. Next, this sheet was molded at a sheet preheating temperature of 150 ° C. by a plug assist type vacuum air pressure molding machine to obtain a cup having a drawing ratio of 1.5 times. When the acetaldehyde content of this cup was measured in the same manner as the sheet, the acetaldehyde content was 0.0038 wt% as in the case of the sheet. The measurement results of the glass transition temperature, the content of acetaldehyde, and the haze value of this sheet are shown in Table 2 below.
The results of the heat deformation resistance test and the acetaldehyde odor sensory test are shown in Table 3 below.

Example 2 As a raw material polyester, 15% by weight of N-2 and T-2 were used.
In the same manner as in Example 1 except that 85% by weight was used, a transparent sheet having a thickness of 0.6 mm and a cup having a draw ratio of 1.5 times were obtained. Table 2 shows the same measurement results as in Example 1 regarding this sheet, and Table 3 shows the same evaluation / test results as in Example 1 regarding this sheet. Example 3 As a raw material polyester, 15% by weight of N-3 and T-3
In the same manner as in Example 1 except that 85% by weight was used, a transparent sheet having a thickness of 0.6 mm and a cup having a draw ratio of 1.5 times were obtained. Table 2 shows the same measurement results as in Example 1 regarding this sheet, and Table 3 shows the same evaluation / test results as in Example 1 regarding this sheet.

Example 4 As a raw material polyester, 50% by weight of N-3 and T-3 were used.
A sheet having a thickness of 0.6 mm in the same manner as in Example 1 except that the resin temperature at the time of extrusion was 300 ° C. and the temperature from the screw tip to the die outlet was 290 ° C. A cup with a draw ratio of 1.5 times was obtained. Table 2 shows the same measurement results as in Example 1 regarding this sheet, and the same evaluation results as in Example 1 regarding this sheet /
The test results are shown in Table 3. Example 5 80% by weight of N-3 as a raw material polyester, T-3
A transparent sheet having a thickness of 0.6 mm in the same manner as in Example 1 except that the resin temperature at the time of extrusion was 310 ° C. and the temperature from the screw tip to the die outlet was 295 ° C. And a drawing ratio of 1. was obtained in the same manner as in Example 1 except that the sheet preheating temperature was 160 ° C.
Five times the cup was obtained. Table 2 shows the same measurement results as in Example 1 regarding this sheet, and Table 3 shows the same evaluation / test results as in Example 1 regarding this sheet.

Example 6 A transparent sheet having a thickness of 0.6 mm was prepared in the same manner as in Example 1 except that 5% by weight of N-4 and 95% by weight of T-4 were used as the raw material polyester. A cup with a draw ratio of 1.5 was obtained. Table 2 shows the same measurement results as in Example 1 regarding this sheet, and Table 3 shows the same evaluation / test results as in Example 1 regarding this sheet. Example 7 20% by weight of N-6 as a raw material polyester, T-3
In the same manner as in Example 1 except that 80% by weight was used, a transparent sheet having a thickness of 0.6 mm and a cup having a drawing ratio of 1.5 were obtained. Table 2 shows the same measurement results as in Example 1 regarding this sheet, and Table 3 shows the same evaluation / test results as in Example 1 regarding this sheet.

Comparative Example 1 Regarding the resin temperature at the time of extrusion,
C., a transparent sheet having a thickness of 0.6 mm and a cup having a draw ratio of 1.5 times were obtained in the same manner as in Example 1 except that the temperature from the screw tip to the die outlet was 290.degree. Table 2 shows the same measurement results as in Example 1 for this sheet.
Table 3 shows the same evaluation / test results as in Example 1 for this sheet.

Comparative Example 2 The thickness was the same as in Example 1 except that the extrusion rate was 160 kg / hr, and the resin temperature during extrusion was 265 ° C. in the cylinder and 270 ° C. from the screw tip to the die outlet. A sheet having a size of 0.6 mm was obtained, and a cup having a drawing ratio of 1.5 was obtained in the same manner as in Example 1 except that the sheet preheating temperature was 180 ° C. An attempt was made to form a sheet with the same extrusion rate as in Example 1, but the power was insufficient, so it was necessary to reduce the extrusion rate by 160 kg / hour. Further, when molding was attempted at the same preheating temperature as in Example 1 but molding could not be performed, it was necessary to raise the sheet preheating temperature to 180 ° C. Therefore, the cycle for molding the cup becomes long. Table 2 shows the same measurement results as in Example 1 regarding this sheet, and Table 3 shows the same evaluation / test results as in Example 1 regarding this sheet.

Comparative Example 3 As a raw material polyester, 50% by weight of N-5 and T-1 were used.
A sheet having a thickness of 0.6 mm was obtained in the same manner as in Example 4 except that 50% by weight was used. Attempts were made to change the preheating temperature, but the sheet broke during molding, and the cup could not be molded. Table 2 shows the same measurement results as in Example 1 regarding this sheet. Comparative Example 4 As the raw material polyester, T-5 was used instead of T-1.
In the same manner as in Example 1 except that 5% by weight was used, a transparent sheet having a thickness of 0.6 mm and a cup having a drawing ratio of 1.5 were obtained. Table 2 shows the same measurement results as in Example 1 regarding this sheet, and Table 3 shows the same evaluation / test results as in Example 1 regarding this sheet.

Comparative Example 5 A transparent sheet having a thickness of 0.6 mm was obtained in the same manner as in Example 5 except that only N-1 was used as the raw material polyester, and the sheet preheating temperature was 180 ° C. A cup with a draw ratio of 1.5 was obtained in the same manner as in Example 5. In addition,
When molding was attempted at the same preheating temperature as in Example 1 but molding could not be performed, it was necessary to raise the sheet preheating temperature to 180 ° C. Therefore, the cycle for molding the cup becomes long. Table 2 shows the same measurement results as in Example 1 regarding this sheet, and Table 3 shows the same evaluation / test results as in Example 1 regarding this sheet. Comparative Example 6 A transparent sheet having a thickness of 0.6 mm and a cup having a draw ratio of 1.5 times were obtained in the same manner as in Example 1 except that only T-1 was used as the raw material polyester. Table 2 shows the same measurement results as in Example 1 regarding this sheet, and Table 3 shows the same evaluation / test results as in Example 1 regarding this sheet.

[0044]

[Table 2]

[0045]

[Table 3]

[0046]

The polyester sheet for drawing produced by the present invention is a conventional polyester transparent sheet,
Excellent in aroma retention, gas barrier property, UV blocking property, moldability, and drawdown resistance. Further, it is possible to provide a squeeze molded article having excellent heat deformation resistance, aroma retaining property, gas barrier property, and ultraviolet blocking property with high productivity. Therefore, the drawn product obtained by drawing the sheet obtained by the present invention, as compared with the drawn product using the conventional polyester transparent sheet, higher heat-resistant deformation and aroma retention, gas barrier properties, It is preferably used as a packaging material that is required to have an ultraviolet blocking property. Furthermore, since the sheet obtained by the present invention has high recyclability, the sheet of the present invention and the draw-formed product using the sheet also have an effect of suppressing the influence on the environment to be small.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jiro Kobe 1 Toho-cho, Yokkaichi-shi, Mie Mitsubishi Chemical Co., Ltd. Yokkaichi Research Institute

Claims (6)

[Claims] 1. A polyethylene naphthalene dicarboxylate having an intrinsic viscosity of 0.5 to 1.3 dl / g, 3 to 98% by weight, and a polyethylene terephthalate having an intrinsic viscosity of 0.5 to 1.5 dl / g, 2 to 97% by weight. Are charged into an extruder to which a die is connected, the resin temperature A in the cylinder of the extruder is 270 to 330 ° C., and the resin temperature B from the screw tip of the extruder to the die outlet is 5 from the resin temperature A. A method for producing a polyester sheet for draw-forming, having a glass transition temperature of 80 ° C or higher and an acetaldehyde content of 0.005% by weight or less, characterized by extruding into a sheet form at a temperature of at least ℃ and at 220 to 300 ° C. 2. The production according to claim 1, wherein the polyethylene naphthalene dicarboxylate has an acetaldehyde content of 0.03% by weight or less, and the polyethylene terephthalate has an acetaldehyde content of 0.03% by weight or less. Method. 3. Polyethylene naphthalene dicarboxylate has a melting peak in the range of 220 to 280 ° C. after heat treatment for 3 hours under nitrogen atmosphere at 200 ° C., or polyethylene terephthalate heat treatment for 3 hours under nitrogen atmosphere at 180 ° C. 2. The method according to claim 1, which has a melting peak in the range of 200 to 260 ° C. after the heating. 4. Polyethylene naphthalene dicarboxylate
The density of the coat is 1.35 g / cm^Three Or above
Lenterephthalate density is 1.36 g / cm ^Three Above
The manufacturing method according to claim 1, wherein: 5. The production method according to claim 1, wherein polyethylene naphthalene dicarboxylate or polyethylene terephthalate is obtained by performing a solid phase polymerization treatment. 6. The manufacturing method according to claim 1, wherein the extruder has a vent port connected to a pressure reducing system having a pressure of 200 mmHg or less.