JP4024066B2 - Multilayer molded body and container - Google Patents

Description

【００５２】
実施例１と比較例２を比較すると、実施例１は２種３層構造をとり、ＰＥＮ系樹脂の全含有量は１８重量%であるのに対し、比較例２では該ＰＥＮ系樹脂の含有量は３０重量％である。しかし耐熱性を比較すると明らかに実施例１の方が耐熱性に優れる。このことにより、本発明の特定の構成からなる多層成形体は、少ない耐熱性樹脂の含有量で高い耐熱性が発現されることが確認された。
【００５３】
また、実施例１および実施例３からは、式（２）を満足することにより、より良好な透明性が達成されることが分かる。実施例１と比較例３から表層にシクロヘキサンジメタノール共重合ポリエチレンテレフタレートを配合しない場合、得られたシートの耐衝撃性が低下することが確認される。
【００５４】
【発明の効果】
本発明によれば、ＰＥＮ系樹脂およびＰＥＴ系樹脂からなりガラス転移温度（Ｔｇ）の異なる樹脂を積層化し、表層に高Ｔｇ、芯層に低Ｔｇである樹脂組成物を用いることにより耐熱性が改善された多層成形体、殊に多層シートが提供される。更に本発明によれば芯層の融点を制御することにより熱成形時の加熱でも結晶化による白化のない、透明性に優れた熱成形された成形品が提供され、その奏する産業上の効果は極めて大である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multilayer molded body, particularly a multilayer sheet. More specifically, the present invention is a polyester multilayer molded body having a specific structure, and is used for thermoforming to produce a heat-resistant container used for applications requiring heat resistance, transparency, impact resistance and economy. The present invention relates to a multilayer molded body particularly suitable as a sheet, particularly a multilayer sheet.
[0002]
[Prior art]
Thermoplastic polyesters are widely used in the field of food packaging and containers such as beverage packaging containers because they are excellent in food safety. For example, a hollow container manufactured by thermoforming a sheet made of polyethylene terephthalate resin is widely known. However, since polyethylene terephthalate resin (hereinafter sometimes referred to as PET) has a glass transition temperature of around 70 ° C., heat resistance may be insufficient depending on the application. In such applications, in recent years, studies have been widely conducted to produce highly heat-resistant containers using polyethylene naphthalate (hereinafter sometimes referred to as PEN) having a glass transition temperature of around 120 ° C. in place of polyethylene terephthalate.
[0003]
However, it is not economical to replace a conventional PET sheet for thermoforming with a PEN sheet as it is because PEN is still expensive. In particular, high economic efficiency is required for food packaging applications that often end their product life in a short period of time. This is because at present, such packaging is often discarded after use. Therefore, studies have been made on multilayer sheets of PEN sheets and PET sheets.
[0004]
The problem with such multilayer sheets is that poor molding occurs because the proper thermoforming temperature differs between PEN and PET. That is, molding failure due to insufficient heating (thickness unevenness, whitening due to voids, etc.) occurs in the PEN layer, and molding failure (whitening, etc.) due to crystallization due to excessive heating occurs in the PEN layer. there were.
[0005]
As an attempt to solve the above problem, for example, Japanese Patent Application Laid-Open No. 03-133640 discloses a polyester multilayer molded article comprising a PET layer and a copolymerized PEN layer obtained by copolymerizing ethylene isophthalate units. However, the invention described as a specific example in this publication is a multilayer molded article having PET as a surface layer, and heat resistance is not sufficiently considered in this invention. In many specific cases, the proportion of PEN is high. Therefore, it is difficult to say that this publication discloses a multilayer molded article having good heat resistance and transparency and excellent in economic efficiency.
[0006]
Japanese Patent Application Laid-Open No. 11-70628 describes a multilayer molded body obtained by laminating a layer composed of a composition composed of PEN and PET and PEN or PET. Further, such a multilayer molded article is characterized in that the crystallization behavior of a layer composed of the composition is controlled to a specific condition and range. However, the invention described as a specific example in such a gazette has a high ratio of PEN in the entire molded body. Therefore, this publication does not fully disclose a multilayer molded article excellent in heat resistance and transparency while sufficiently satisfying economic efficiency. Furthermore, when PEN was used for the surface layer, the resulting multilayer molded article had low impact resistance, and an improvement thereof was desired.
[0007]
[Problems to be solved by the invention]
As described above, a multilayer molded article having a multilayer structure of PEN and PET has a drawback that transparency is impaired when the PET layer is crystallized when heated to PEN molding conditions during thermoforming. On the other hand, for example, in food packaging applications, it is required to make the contents look beautiful, that is, high transparency. Further, in food packaging applications, it may be desired that food can be heated in a container, that is, excellent heat distortion resistance, in order to sterilize, cook, and warm the food. Further, as described above, high economic efficiency is required for such food packaging applications, and particularly, good impact resistance is also required for food containers.
[0008]
Therefore, the present invention provides a molded article having excellent transparency, heat distortion resistance, impact resistance, and economy, and in particular, has these characteristics that can produce a container without crystallization during thermoforming. It is an object of the present invention to provide a satisfactory thermoforming sheet.
[0009]
[Means for Solving the Problems]
That is, the present invention relates to a core layer (A layer) composed of a resin composition comprising a polyethylene terephthalate resin and a polyethylene naphthalate resin, and 2 to 50 mol of cyclohexanedimethanol as a copolymer component in 100 mol% of all diol components. Copolymerized polyethylene terephthalate resin 1 to 50% by weight, polyethylene naphthalate resin 50 to 99% by weight and polyethylene terephthalate resin 0 to 40% by weight of the surface layer (B layer) The layer B is laminated on both sides of the layer A, and (I) satisfies the condition of the following formula (1), and (II) the ratio of the thickness of the layer A and the layer B (layer B: A layer: B layer) is a multilayer composition in the range of B layer: A layer: B layer = 5-25: 50-90: 5-25, where the total thickness of the layers is 100. It relates to the body.
T _g BT _g A ≧ 10 (1)
(Where T _g A is the glass transition temperature (° C.) of the resin composition constituting the core layer (A layer) measured according to JIS K7121, T _g B is the glass transition temperature (° C.) of the resin composition constituting the surface layer (B layer) measured according to JIS K7121. )
[0010]
One of the preferred embodiments of the present invention is that the resin composition constituting the layer A is a polyethylene terephthalate resin 80 to 97 in a total of 100% by weight of the polyethylene terephthalate resin and the polyethylene naphthalate resin. The multilayer molded body is composed of 3% by weight and 3 to 20% by weight of polyethylene naphthalate resin.
[0011]
One of the preferred embodiments of the present invention relates to (III) the multilayer molded article that further satisfies the condition of the following formula (2).
(T _g BT _g A) / 10 ≦ 253-T _m A (2)
(Where T _m A is the melting point (° C.) of the resin composition constituting the core layer (A layer) measured in accordance with JIS K7121, and T _g B and T _g A is the same as the above formula (1). )
[0012]
One of the preferred embodiments of the present invention relates to the multilayer molded article, wherein the polyethylene naphthalate resin contains 5 to 12 mol% of terephthalic acid as a copolymer component in 100 mol% of the total acid components.
[0013]
One of the preferred embodiments of the present invention relates to the multilayer molded body, wherein the multilayer molded body is a multilayer sheet.
[0014]
One of the preferred embodiments of the present invention relates to a container formed by thermoforming the multilayer sheet.
[0015]
Details of the present invention will be described below.
The core layer (A layer) of the present invention is composed of a resin composition comprising a polyethylene terephthalate resin and a polyethylene naphthalate resin. The polyethylene terephthalate-based resin (hereinafter sometimes referred to as “PET-based resin”) in the A layer is a main repeating unit of ethylene terephthalate, the dicarboxylic acid component of which is 85 mol% or more, and a diol component As a polyester resin containing 85 mol% or more of ethylene glycol. The PET-based resin in the A layer preferably contains 90 mol% or more, more preferably 95 mol% or more of a terephthalic acid component as a dicarboxylic acid component. The PET resin in the A layer preferably contains 90 mol% or more, more preferably 95 mol% or more of ethylene glycol as a diol component.
[0016]
The polyethylene naphthalate resin (hereinafter sometimes referred to as “PEN resin”) in layer A is ethylene naphthalate as the main repeating unit, and 2,6-naphthalenedicarboxylic acid component is 75 as its dicarboxylic acid component. It is a polyester resin containing at least 85 mol% of ethylene glycol as a diol component. The PEN-based resin in the A layer preferably contains 80 mol% or more, more preferably 85 mol% or more of a 2,6-naphthalenedicarboxylic acid component as a dicarboxylic acid component. Further, the PEN resin in the A layer preferably contains 87 mol% or more, more preferably 90 mol% or more of ethylene glycol as a diol component.
[0017]
Examples of other dicarboxylic acid components in the PET resin and PEN resin include, for example, terephthalic acid (in the case of PEN resin), isophthalic acid, 2-chloroterephthalic acid, 2,5-dichloroterephthalic acid, 2-methyl Terephthalic acid, 4,4-stilbene dicarboxylic acid, 4,4-biphenyldicarboxylic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid (in the case of PET resin), 2,7-naphthalenedicarboxylic acid, bisbenzoic acid, bis (P-carboxyphenyl) methane, anthracene dicarboxylic acid, 4,4-diphenyl ether dicarboxylic acid, 4,4-diphenoxyethanedicarboxylic acid, 5-Na sulfoisophthalic acid, and ethylene-bis-p-benzoic acid . These dicarboxylic acids can be used alone or in admixture of two or more.
[0018]
In addition to the aromatic dicarboxylic acid, an aliphatic dicarboxylic acid component can be copolymerized with the PET resin and PEN resin. Examples of the aliphatic dicarboxylic acid component include adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, 1,3-cyclohexanedicarboxylic acid, and 1,4-cyclohexanedicarboxylic acid.
[0019]
Examples of other diol components in the PET resin and PEN resin include ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propanediol, 2,2-dimethyl-1,3-propanediol, trans -Or -2,2,4,4-tetramethyl-1,3-cyclobutanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 1,4- Examples include cyclohexanedimethanol, 1,3-cyclohexanedimethanol, decamethylene glycol, cyclohexanediol, p-xylenediol, and bisphenol A. These can be used alone or in admixture of two or more. Furthermore, PET resins and PEN resins obtained by slightly copolymerizing polyethylene glycol as the diol component can also be used. The molecular weight of polyethylene glycol is preferably in the range of 150 to 6,000.
[0020]
The PET resin and PEN resin of the A layer can be used alone or in combination of two or more.
[0021]
Among the above, the PET resin of the A layer is preferably a polyester resin which does not contain other copolymer components and is substantially produced only from a terephthalic acid component and an ethylene glycol component. However, even in such a polyester resin, about 0.5 mol% or more of a diethylene glycol component is usually contained in 100 mol% of the diol component as a side reaction product during polymerization. Therefore, a suitable PET resin for the A layer may contain a small amount of a diethylene glycol component. The diethylene glycol component is preferably 6 mol% or less, more preferably 5 mol% or less, and still more preferably 4 mol% or less, in 100 mol% of the diol component.
[0022]
Among the above, the PEN resin of the A layer is composed of 85 mol% or more of 2,6-naphthalenedicarboxylic acid component and 15 mol% or less of terephthalic acid as dicarboxylic acid component, and substantially only ethylene glycol component as diol component. The produced polyester resin is preferred. Such a preferred PEN resin of the A layer preferably does not contain a terephthalic acid component from the viewpoint of heat resistance.
[0023]
However, in order to satisfy the condition (2) which is a more preferred embodiment of the present invention, it is advantageous that the melting point of the resin composition is low in the core layer (A layer). Satisfactory transparency can be obtained by satisfying these conditions. In order to satisfy the formula (2), good compatibility between the PET resin and the PEN resin is required in the resin composition of the A layer. The copolymerization of terephthalic acid in the PEN resin is effective in this respect, and there is little decrease in heat resistance. From the viewpoint of the transparency of the resin composition, when the terephthalic acid component is copolymerized in the PEN resin of the A layer, the content is preferably 5 mol% or more in 100 mol% of the dicarboxylic acid. The proportion of the terephthalic acid component is more preferably 5 to 12 mol%, more preferably 8 to 12 mol%, in 100 mol% of the dicarboxylic acid.
[0024]
The ratio of the PET-based resin and the PEN-based resin in the resin composition constituting the core layer (A layer) is not particularly limited as long as it satisfies the requirement of formula (1). However, it is not preferable that the amount of PEN resin is unnecessarily large in terms of economy. More preferably, the resin composition is 80 to 97% by weight of a PET resin and 3 to 20% by weight of a PEN resin in a total of 100% by weight of a PET resin and a PEN resin, and more preferably a PET resin. The resin is 90 to 96% by weight and the PEN resin is 4 to 10% by weight, particularly preferably the PET resin 93 to 96% by weight and the PEN resin 4 to 7% by weight.
[0025]
Next, the resin composition constituting the surface layer (B layer) will be described. The surface layer (B layer) of the present invention comprises 1 to 50% by weight of a copolymerized polyethylene terephthalate resin containing 2 to 50% by mole of cyclohexanedimethanol as a copolymer component in 100% by mole of all diol components, and 50 to 99% by weight of a PEN resin. % And a resin composition comprising 0 to 40% by weight of a PET-based resin.
[0026]
As the PET resin for the B layer, the same one as the PET resin for the A layer can be used. Also, the PEN resin for the B layer can be the same as the PET resin for the A layer. It is the same as in the case of the A layer that both can be used alone or in combination of two or more. Further, the PET resin for the A layer and the PET resin for the B layer can be selected either when they are the same or different from each other. This relationship is the same for the PEN resin in the A layer and the PEN resin in the B layer.
[0027]
Suitable PEN-based resins in the B layer are, as in the A layer, 85 mol% or more of 2,6-naphthalenedicarboxylic acid component and 15 mol% or less of terephthalic acid as the dicarboxylic acid component, and substantially ethylene as the diol component. It is a polyester resin produced only from the glycol component. In a suitable PEN-based resin in the B layer, the proportion of the dicarboxylic acid component can be appropriately adjusted depending on which of heat resistance, transparency, impact resistance, and economic properties are more important. When emphasizing transparency, the proportion of the terephthalic acid component is more preferably 5 to 12 mol%, more preferably 8 to 12 mol%, in 100 mol% of the dicarboxylic acid.
[0028]
The resin composition constituting the B layer is a copolymerized polyethylene terephthalate resin (hereinafter referred to as “CHDM copolymerized PET resin”) containing 2 to 50 mol% of cyclohexanedimethanol as a copolymer component in 100 mol% of all diol components. Is an essential component. By making such a component an essential component at a specific ratio, the B layer can have good impact resistance and transparency without a decrease in heat resistance. As a result, it is possible to provide a multilayer molded body having these characteristics, particularly a container.
[0029]
Such a CHDM copolymerized PET resin includes 85 mol% or more of a terephthalic acid component as a dicarboxylic acid component, and 50 to 98 mol% of an ethylene glycol component and a cyclohexanedimethanol component 2 in 100 mol% of all diol components as a diol component. It is a polyester resin containing ˜50 mol%, and the total of ethylene glycol component and cyclohexanedimethanol component is 85 mol% or more in 100 mol% of all diol components. The CHDM copolymerized PET-based resin in layer B preferably contains 90 mol% or more, more preferably 95 mol% or more of terephthalic acid as a dicarboxylic acid component. Moreover, it is preferable that the CHDM copolymerization PET-type resin in B layer contains 10-40 mol% of cyclohexanedimethanol components in 100 mol% of all diols as a diol component, and 20-30 mol% is more preferable. Further, the CHDM copolymerized PET resin preferably contains 60 to 90 mol%, more preferably 70 to 80 mol% of the ethylene glycol component in 100 mol% of all diols as the diol component. Further, the CHDM copolymerized PET resin preferably contains 90 mol% or more, more preferably 95 mol% or more of the cyclohexanedimethanol component and the ethylene glycol component in 100 mol% of the total diol.
[0030]
Here, examples of cyclohexanedimethanol include 1,4-cyclohexanedimethanol and 1,3-cyclohexanedimethanol, and 1,4-cyclohexanedimethanol is more preferable.
[0031]
The PET resin in the core layer (A layer) may contain the above CHDM copolymerized PET resin.
[0032]
The molecular weights of the above various polyester resins are preferably such that the intrinsic viscosity measured at 35 ° C. using o-chlorophenol as a solvent is in the range of 0.4 to 1.3 dl / g, 0.45 to 1.2 dl. The range of / g is more preferable. Moreover, although the terminal carboxyl group amount of the resin composition which comprises said each layer is not restrict | limited in particular, 30 eq / ton or less is preferable and 25 eq / ton or less is still more preferable. A lower limit of 5 eq / ton or more is practically appropriate.
[0033]
Said various polyester resin can be manufactured by a conventionally well-known manufacturing method. That is, dicarboxylic acid and diol are directly reacted to distill off water and esterify, followed by direct esterification by polycondensation under reduced pressure, or dicarboxylic acid dimethyl ester and diol to react to distill off methyl alcohol and ester After the exchange, it is produced by a transesterification method in which polycondensation is performed under reduced pressure. Further, solid state polymerization can be performed to increase the intrinsic viscosity number.
[0034]
In the transesterification or esterification reaction and polycondensation reaction, it is preferable to use a catalyst and a stabilizer. As the transesterification catalyst, Mg compound, Mn compound, Ca compound, Zn compound and the like are used. Examples thereof include acetates, monocarboxylates, alcoholates and oxides thereof. Further, the esterification reaction can be carried out only with dicarboxylic acid and diol without adding a catalyst, but can also be carried out in the presence of a polycondensation catalyst described later.
[0035]
As the polycondensation catalyst, Ge compounds, Ti compounds, Sb compounds and the like can be used, and examples thereof include germanium dioxide, germanium hydroxide, germanium alcoholate, titanium tetrabutoxide, titanium tetraisopropoxide, and titanium oxalate. . It is preferable to use a phosphorus compound as a stabilizer. Preferable phosphorus compounds include phosphoric acid and its ester, phosphorous acid and its ester, hypophosphorous acid and its ester, hypophosphorous acid and its ester, and the like. In addition, during the esterification reaction, a tertiary compound such as triethylamine, a quaternary ammonium hydroxide such as tetraethylammonium hydroxide, and a basic compound such as sodium carbonate can be added to suppress diethylene glycol by-product. Moreover, various stabilizers and modifiers can be blended in the obtained polyester resin.
[0036]
The multilayer molded body of the present invention is obtained by laminating a surface layer (B layer) on both surfaces of the core layer (A layer), and further satisfies (I) the condition of the following formula (1) and (II) A layer And the ratio of the thickness of the B layer (B layer: A layer: B layer), where the total thickness of the layers is 100, the B layer: A layer: B layer = 5-25: 50-90: 5 It is in the range of ˜25.
T _g BT _g A ≧ 10 (1)
(Where T _g A is the glass transition temperature (° C.) of the resin composition constituting the core layer (A layer) measured according to JIS K7121, T _g B is the glass transition temperature (° C.) of the resin composition constituting the surface layer (B layer) measured according to JIS K7121. )
[0037]
The present invention uses the specific core layer (A layer) and the surface layer (B layer), and has a configuration satisfying such specific conditions, thereby improving heat resistance, transparency, impact resistance, and economic efficiency. It is possible to provide an excellent multilayer molded article. In the above formula (1), when the glass transition temperature of the B layer with respect to the A layer is not higher than 10 ° C., the effect of improving the heat resistance due to the multilayering cannot be obtained sufficiently. The resin composition constituting the B layer is suitable in this respect, and is excellent in transparency and impact resistance. These glass transition temperatures are calculated by DSC measurement (differential scanning calorimetry) at a rate of temperature increase of 20 ° C./min in accordance with JIS K7121.
[0038]
(T in the above formula (1) _g BT _g A suitable upper limit for A) is 50 ° C. (T _g BT _g When A) is 50 ° C. or higher, the absolute value of the glass transition temperature of the A layer may be insufficient and the heat resistance may decrease. Therefore, the above formula (1) is more preferably when the condition of the following formula (3) is satisfied, further preferably the following formula (4) is satisfied, and particularly preferably the following formula (5) is satisfied.
10 ≦ T _g BT _g A ≦ 50 (3)
15 ≦ T _g BT _g A ≦ 40 (4)
20 ≦ T _g BT _g A ≦ 40 (5)
T _g The absolute value of A is preferably 65 to 75 ° C, more preferably 70 to 74 ° C.
[0039]
Further, the ratio of the thickness of the core layer (A layer) and the surface layer (B layer) in the multilayer molded body of the present invention (B layer: A layer: B layer), when the total thickness of the layers is 100, B layer: A layer: B layer = 5-25: 50-90: 5-25, B layer: A layer: B layer = 8-15: 70-84: 8-15 Is more preferable. When the thickness ratio of the surface layer (B layer) is smaller than 5, the heat resistance becomes insufficient, and when the thickness ratio exceeds 25, the ratio of the expensive PEN resin increases, whereas the heat resistance increases. Since there is little improvement effect, it is not preferable in terms of economy.
[0040]
The thicknesses of the B layers stacked on both sides of the A layer may be the same or different, but are preferably substantially the same. Further, the thickness is not necessarily constant in the multilayer molded body, and the thickness may change continuously or discontinuously.
[0041]
Although the thickness of a multilayer molded object is not specifically limited, The range of 50-1000 micrometers is preferable, The range of 100-600 micrometers is more preferable, The range of 150-500 micrometers is still more preferable.
[0042]
The present invention more preferably satisfies the following formula (2).
(T _g BT _g A) / 10 ≦ 253-T _m A (2)
(Where T _m A is the melting point (° C.) of the resin composition constituting the core layer (A layer) measured in accordance with JIS K7121, and T _g B and T _g A is the same as the above formula (1). )
[0043]
By satisfying the condition of the above formula (2), it is possible to obtain a multilayer molded body having excellent transparency, particularly a multilayer sheet for thermoforming. Therefore, it is preferable that the resin composition of A layer is adjusted so that the conditions of Formula (2) may be satisfied. For example, a polyethylene terephthalate resin and a polyethylene naphthalate resin are originally incompatible, but compatibilization proceeds with a transesterification reaction by mixing in a molten state. The melting point decreases due to the progress of compatibilization, and the above T _m The value of A can be reduced. That is, it is preferable that not only a resin composition but the manufacturing conditions of a multilayer molded object are adjusted so that the resin composition which comprises a core layer (A layer) may satisfy | fill Formula (2). T _m Although it does not specifically limit as an absolute value of A, The range of 245-250 degreeC is preferable, and the range of 246-249 degreeC is more preferable.
[0044]
The multilayer molded body of the present invention is not particularly limited in its form, but since good transparency can be achieved even in thermoforming, the multilayer sheet and a molded article produced from the multilayer sheet by thermoforming, in particular, a container. It is preferable that Among containers, food packaging containers are most suitable. Examples of the sheet production method include a T-die method in which a resin composition constituting the layer is melt-extruded from a T-die, a calendar molding method, a solvent casting method, and an inflation method, but the T-die method is most preferred. It is. Further, when manufacturing a sheet by the T-die method, multilayering methods include a method of laminating a molten resin in a T-die and a method of multilayering by coating a molten resin on a previously manufactured sheet. Can be taken. Such a multilayering method can be similarly applied to methods other than the T-die method. Moreover, the method of laminating | stacking the sheet | seat manufactured independently for each layer can also be taken. Among the above, the multilayer sheet of the present invention is preferably formed by a T-die method in which molten resin is laminated in a T-die.
[0045]
As a method for thermoforming the multilayer sheet of the present invention, known vacuum forming, vacuum forming with plug assist, vacuum / pressure forming, or the like can be used. Furthermore, molded products obtained by thermoforming multilayer sheets can be used in a wide range of fields, including packaging applications, various electronic and electrical equipment, vehicles, industrial machinery, agricultural materials, fishery materials, toys, medical care, and miscellaneous goods. In particular, it has characteristics suitable for food packaging applications.
[0046]
【Example】
Hereinafter, examples in which the present invention is implemented will be described. The present invention is not limited to these examples.
(1) Used resin
The following resins 1 to 4 were used as a raw material resin composition constituting the multilayer sheet.
Resin 1: [Polyethylene terephthalate]
Polyethylene terephthalate pellets (polyethylene terephthalate PET resin, which has a limiting viscosity number of 0.75 measured in o-chlorophenol at 35 ° C., consisting of terephthalic acid as the dicarboxylic acid component constituting the polyester and ethylene glycol as the diol component) : TR8550T)
Resin 2: [Cyclohexanedimethanol copolymerized polyethylene terephthalate]
Polyester terephthalate pellets (yeast produced by copolymerizing 20 mol% of cyclohexanedimethanol with 100 mol% of the total amount of diol components, with terephthalic acid as the main component constituting the polyester and diol component as the main component. Man Chemical Co., Ltd .: EASTAR6763)
Resin 3: [Polyethylene-2,6-naphthalenedicarboxylate]
It consists of 100 mol% naphthalenedicarboxylic acid in 100 mol% dicarboxylic acid component and 100 mol% ethylene glycol in 100 mol% diol component, and its intrinsic viscosity measured at 35 ° C in o-chlorophenol is 0.55. Polyethylene-2,6-naphthalenedicarboxylate pellets (Teijin Limited: Teonex TN8050)
Resin 4: [Copolymerized polyethylene-2,6-naphthalenedicarboxylate]
Consists of 8 mol% terephthalic acid and 92 mol% naphthalene dicarboxylic acid in 100 mol% dicarboxylic acid component, and 100 mol% ethylene glycol in 100 mol% diol component, measured in o-chlorophenol at 35 ° C. Copolymer polyethylene-2,6-naphthalenedicarboxylate pellets having an intrinsic viscosity of 0.49 (manufactured by Teijin Limited: Teonex TN8756)
[0047]
(2) Manufacture of multilayer sheets
Each of the above resin raw materials is uniformly mixed by a tumbler at the ratio shown in Table 1, and then supplied to a single-axis 40 mmφ (for core layer) and single-axis 30 mmφ (for surface layer) extruder, respectively, and connected to the extruder. An unstretched sheet having a thickness of 0.3 mm and a two-layer / three-layer structure was manufactured using the multilayer T-die. A temperature adjuster is connected to the cooling roll, and the cooling temperature can be freely controlled. The temperature is adjusted to 30 ° C. where the production is most stable in each sheet. In the embodiment, T in the formula (1) _m A was changed by (i) changing the resin composition and (ii) changing the molten resin temperature during film formation by changing the cylinder temperature or the like. The molten resin temperature was determined by directly measuring the temperature of the resin discharged from the T die. The thickness ratio of the surface layer / core layer was adjusted by the discharge amount of each extruder. The ratio of the thickness of each layer of the obtained sheet was measured by observing the sheet cross section with a polarizing microscope.
[0048]
(3) Evaluation of multilayer sheet
The following (I) and (II) ((i) to (iii)) were evaluated.
(I) DSC measurement of each layer
From the multilayer sheet produced above, the resin of the surface layer portion or the core layer portion was shaved and subjected to DSC measurement. The DSC measurement was performed at a heating rate of 20 ° C./min in accordance with JIS K7121 standard.
(II) Container evaluation
A box-shaped container molded product having a length of 21 cm, a width of 15 cm, and a depth of 4 cm was formed from the multilayer sheet produced above by a vacuum forming method. By adjusting the heating time of the sheet, the sheet temperature was changed from 90 to 140 ° C. The obtained container was visually observed for its traceability to the mold using the rib shape at the bottom of the molded product as a criterion. The sheet temperature at the time of vacuum forming was set to a temperature at which the traceability was the best without whitening due to crystallization. The mold temperature was 40 ° C. The following (i)-(iii) evaluation was performed about the container obtained on this condition.
[0049]
(i) Haze evaluation of containers
The haze of the box-shaped container molded product obtained by thermoforming the multilayer sheet was measured according to JIS K7361.
(Ii) Evaluation of heat resistance of container
A box-shaped container molded product obtained by thermoforming the multilayer sheet was placed in a hot air dryer at a predetermined temperature (70 ° C., 80 ° C., and 90 ° C.), and the volume change rate after 10 minutes was measured. The volume change rate was calculated as a ratio (%) of the volume contracted by the heat treatment with respect to the initial volume. That is, it is “0%” if there is no change, and “30%” if the volume after heat treatment is 70% of the initial volume.
(Iii) Container impact test
An impact test based on JISK7124-2 was performed at room temperature on a box-shaped container molded product obtained by thermoforming a multilayer sheet, and the total amount of energy penetrating was obtained.
[0050]
Table 1 shows the conditions and results of Examples and Comparative Examples.
[0051]
[Table 1]

[0052]
Comparing Example 1 and Comparative Example 2, Example 1 has a two-layer three-layer structure, and the total content of PEN resin is 18% by weight, whereas Comparative Example 2 contains the PEN resin. The amount is 30% by weight. However, when heat resistance is compared, Example 1 is clearly superior in heat resistance. Accordingly, it was confirmed that the multilayer molded article having a specific configuration of the present invention exhibits high heat resistance with a small content of the heat resistant resin.
[0053]
Moreover, from Example 1 and Example 3, it turns out that more favorable transparency is achieved by satisfying Formula (2). From Example 1 and Comparative Example 3, it is confirmed that when the cyclohexanedimethanol copolymerized polyethylene terephthalate is not blended in the surface layer, the impact resistance of the obtained sheet is lowered.
[0054]
【The invention's effect】
According to the present invention, heat resistance is improved by laminating resins composed of PEN resin and PET resin and having different glass transition temperatures (Tg), and using a resin composition having a high Tg for the surface layer and a low Tg for the core layer. An improved multilayer molded body, in particular a multilayer sheet, is provided. Furthermore, according to the present invention, by controlling the melting point of the core layer, there is provided a thermoformed molded article excellent in transparency without whitening due to crystallization even by heating during thermoforming, and the industrial effect exhibited by the product is It is extremely large.

Claims (6)

A core layer (A layer) composed of a resin composition comprising a polyethylene terephthalate resin and a polyethylene naphthalate resin, and a copolymer comprising 2 to 50 mol% of cyclohexanedimethanol as a copolymer component in 100 mol% of all diol components It has a surface layer (B layer) composed of a resin composition consisting of 1 to 50% by weight of polymerized polyethylene terephthalate resin, 50 to 99% by weight of polyethylene naphthalate resin and 0 to 40% by weight of polyethylene terephthalate resin, and A B layers are laminated on both sides of the layer, and (I) the condition of the following formula (1) is satisfied, and (II) the ratio of the thickness of the A layer and the B layer (B layer: A layer: B layer) ) Is a multilayer laminate in a range of B layer: A layer: B layer = 5-25: 50-90: 5-25, where the total thickness of the layers is 100.
50 ≧ T _g B−T _g A ≧ 10 (1)
(Here, T _g A is the glass transition temperature (° C.) of the resin composition constituting the core layer (A layer) measured according to JIS K7121, and T _g B is measured according to JIS K7121. (The glass transition temperature (° C.) of the resin composition constituting the surface layer (B layer).)   The resin composition constituting the layer A is composed of 80 to 97% by weight of polyethylene terephthalate resin and 3 to 20% by weight of polyethylene naphthalate resin in a total of 100% by weight of the polyethylene terephthalate resin and polyethylene naphthalate resin. The multilayer molded body according to claim 1. Furthermore, (III) The multilayer molded object of any one of Claim 1 or 2 which satisfies the conditions of following formula (2).
(T _g B−T _g A) / 10 ≦ 253−T _m A (2)
(Here, T _m A is the melting point (° C.) of the resin composition constituting the core layer (A layer) measured according to JIS K7121, and T _g B and T _g A are expressed in the above formula (1). Same.)   The multilayer molded article according to any one of claims 1 to 3, wherein the polyethylene naphthalate-based resin contains 5 to 12 mol% of terephthalic acid as a copolymer component in 100 mol% of the total acid components.   The multilayer molded body according to any one of claims 1 to 4, wherein the multilayer molded body is a multilayer sheet.   A container formed by thermoforming the multilayer sheet of claim 5.