JP2003225981A - Multilayer polyester sheet, film and molded product made thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer polyester sheet which has excellent heat resistance, impact resistance and container moldability and in which a mold stain at a molding time is solved and to provide its molded product. <P>SOLUTION: The multilayer polyester sheet comprises a front layer made of a polyester resin, inorganic fine particles and a wax, and an inner layer made of a polyester resin, inorganic fine particles, a wax and a polyolefin resin. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester sheet suitable for obtaining molded articles such as trays which are required to have properties such as heat resistance and impact resistance. TECHNICAL FIELD The present invention relates to a polyester-based sheet that has solved mold stains at times, and a molded product made from them.

[0002]

2. Description of the Related Art Due to widespread use of household microwave ovens and ovens, there is a need for food trays that can be used at high temperatures. In particular, as a tray for semi-cooked frozen food, it is necessary to withstand not only high temperature conditions during cooking but also freezing conditions during storage, that is, a wide temperature range of about -20 ° C to about 220 ° C. At present, as a food tray having the above characteristics, a crystallized resin tray obtained by crystallizing a polyester sheet mainly made of polyethylene terephthalate resin (hereinafter referred to as PET) at the time of molding a container has been put into practical use.

However, the polyester-based sheet made of PET has been problematic in that the molding cycle during the production of the container is relatively long because it takes time to crystallize when the container is thermoformed. Further, although such a tray made of PET has sufficient heat resistance, it cannot be said to have sufficient impact resistance, and there is a drawback that the container is significantly damaged by the impact.

In order to solve the above problem, a polyester sheet made of a resin (hereinafter referred to as C-PET) in which a small amount of polyolefin is added to PET has been proposed.
It is known that the crystallinity of the C-PET sheet at the time of thermoforming is higher than that of the PET sheet, and that the C-PET sheet is relatively excellent in formability. It is also known that the impact resistance of a container obtained from a C-PET sheet is better than that of a container made of a PET sheet.

When this type of food tray is produced by thermoforming a sheet, in addition to the above characteristics, the amount of sagging of the sheet during preheating is optimized, the releasability from the die is improved, and the stain on the die is prevented. It is also necessary to improve moldability by reducing the amount of adhesion and shortening the molding cycle. However, the above C-PE
In T, there is a problem that the polyolefin adheres to the mold at the time of molding, that is, the mold is significantly contaminated, and its early solution is desired.

As a method for improving the above-mentioned drawbacks, a sheet using a modified polyolefin or a polyethylene ionomer as a polyolefin and a sheet containing a general-purpose crystal nucleating agent have been proposed.

However, the former sheet does not essentially solve the problem of mold fouling, and the latter sheet does not cause mold fouling, but has the drawback of being inferior in impact resistance. Was wanted.

[0008]

As described above, the existing polyester sheet and the molded article made of the sheet solve various problems in molding and use thereof, particularly mold stains and impact resistance. I can't. Based on the above background, the present invention is a polyester-based sheet suitable for obtaining molded articles such as trays that are required to have properties such as heat resistance and impact resistance, and more specifically, excellent in crystallinity and container moldability, and molded. It is an object of the present invention to provide a polyester sheet that solves the problem of mold fouling at that time, and a molded product thereof.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, use inorganic fine particles as a crystal nucleating agent in the surface layer and polyolefin in addition to them in the inner layer. The inventors have found that the above problems can be solved by using them, and have reached the present invention.

That is, the present invention is as follows. 1. A surface layer containing a polyester resin and inorganic fine particles and substantially not containing a polyolefin resin, and an inner layer containing a polyester resin, inorganic fine particles and a polyolefin resin, (inorganic fine particle content (% by weight)) ) / (Content of inorganic fine particles in surface layer (% by weight)) is 0.
A multi-layer polyester sheet characterized by having a range of 5 to 1.5. 2. 2. The multilayer polyester sheet according to the above 1, wherein the average particle size of the inorganic fine particles is 10 μmφ or less. 3. The polyolefin resin has a density (ρ) of 0.9
^3. The multilayer polyester sheet according to any one of 1 or 2 above, which is a polyolefin resin satisfying at least one of 1 g / cm ³ or less and a melt index (MI) of 10 g / 10 min or more. . 4. 7. The multilayer polyester sheet according to any one of 1 to 6 above, wherein the surface layer has a thickness of at least 10 μm. 5. 8. The multilayer polyester sheet according to any one of 1 to 7 above, wherein the polyester is a polyester whose main repeating unit is ethylene terephthalate. 6. A molded product formed from the multilayer polyester sheet according to any one of 1 to 8 above.

[0011]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below. The polyester used in the polyester sheet in the present invention includes, for example, PET, polypropylene terephthalate, polybutylene terephthalate, polycyclohexanedimethylene terephthalate, polyethylene naphthalate, polypropylene naphthalate, polybutylene naphthalate, liquid crystalline polyester and any of the above polyesters. The thing which added the crystal nucleating agent is mentioned.

The intrinsic viscosity of the polyester used in the present invention is preferably 0.70 dL / g or more, more preferably 0.80 dL / g or more. Intrinsic viscosity is 0.7
When it is 0 dL / g or less, the obtained sheet and its molded product are inferior in mechanical strength, and the operation failure is likely to occur due to sheet sagging in the sheet preheating step at the time of container molding, which is not preferable. Intrinsic viscosity is 2.0 dl / g
The following is preferable.

The polyester of the present invention may use aromatic dicarboxylic acids of other species, alicyclic dicarboxylic acids and aliphatic dicarboxylic acids as a part of its acid component. Aromatic dicarboxylic acids include terephthalic acid, 2,6-naphthalenedicarboxylic acid, isophthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, hydroxybenzoic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenoxy. Examples thereof include ethanedicarboxylic acid, 3,5-dicarboxybenzenesulfonic acid and 5-sodium sulfoisophthalic acid. Examples of the alicyclic dicarboxylic acid include cyclohexanedicarboxylic acid and tetrahydrophthalic anhydride. Examples of the aliphatic dicarboxylic acid include succinic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, dimer acid, hydrogenated dimer acid and the like. These are used within a range that does not significantly lower the melting point and crystallinity of the resin, and the amount is 20 mol% of the total acid component
Less, preferably less than 10 mol%.

As the polyester in the present invention, other kinds of glycols, that is, alkylene glycols having 1 to 25 carbon atoms can be used as a part of the glycol component. For example, diethylene glycol, 1,2-propylene glycol, 1,3-probandiol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,9-nonane. Examples include diol, neopentyl glycol, dimethylol heptane, dimethylol pentane, tricyclodecane dimethanol, and an ethylene oxide derivative of bisphenol X (X is A, S, F). These glycols are used in an appropriate combination depending on the balance of various properties, but it is a prerequisite that the crystallinity of the main ester unit in the polymer is not hindered, so the copolymerization amount is 20 mol% of the total glycol component. The following is desirable.

The polyester of the present invention may contain a trifunctional or higher polycarboxylic acid or polyol component only in a small amount. For example, trimellitic anhydride, benzophenonetetracarboxylic acid, trimethylolpropane, glycerin, pyromellitic dianhydride, pentaerythritol, 5-hydroxyisophthalic acid and the like can be used at 3 mol% or less.

The polyesters according to the invention can also contain only a small amount of difunctional polyether components.
For example, PTMG, ethylene oxide modified PTMG, or the like can be used in an amount of 10% by weight or less. Further, compounds such as p-phenylphenol, benzyloxybenzoic acid, naphthalene monocarboxylic acid, polyethylene glycol monomethylene ether and the like can be used in an amount of 10% by weight or less.

As the polyester in the present invention, any of the above-mentioned ones may be used alone, or two or more kinds thereof may be mixed and used. When two or more kinds of polyesters are mixed and used, at least one kind may be selected from the above-mentioned ones, and other polyesters may have an arbitrary composition. For example, terephthalic acid, ethylene glycol,
Amorphous resin consisting of cyclohexanedimethanol, terephthalic acid, ethylene glycol, amorphous resin consisting of neopentyl glycol, terephthalic acid, isophthalic acid,
Examples of the amorphous resin include ethylene glycol, but the invention is not limited thereto.

The inorganic fine particles used in the present invention are not particularly limited as long as they are fine particles of an inorganic substance composed of an arbitrary element, and inorganic salts, inorganic oxides, and more preferably inorganic substances are preferably used as the inorganic substance. It is an oxide. The inorganic oxide is defined as various oxygen-containing metal compounds in which a metal element mainly forms a three-dimensional network through a bond with an oxygen atom. As the metal element forming the inorganic oxide, for example, an element selected from Groups I to VI of the Periodic Table of the Elements is preferable. Among them, Si, Mg, Al, F
An element selected from e, Ca, K, Na, Ti and Zr is particularly preferable, and fine particles in which the main metal elements constituting the inorganic oxide are Si and Mg are most preferable as the inorganic fine particles. In addition, even if the inorganic oxide contains an organic group or a hydroxyl group, or various groups derived from the metal compound (G) as a raw material described later remain, or a part of the organic polymer is included. Good. The organic group is at least one selected from the group consisting of an optionally substituted alkyl group having 20 or less carbon atoms, a cycloalkyl group, an aryl group, and an aralkyl group. The inorganic oxides may be used alone or in combination of two or more. Examples of preferable inorganic fine particles other than talc include mica, calcium carbonate,
Examples thereof include magnesium carbonate, titanium oxide, aluminum oxide, silica, silicate, barium sulfate, crustonite, kaolin, carbon black and zinc oxide.

The shape of the inorganic fine particles made of such an inorganic material may be any particle shape such as spherical, needle-like, plate-like, scale-like, and crushed, and is not particularly limited.

The inorganic fine particles used in the present invention preferably have an average particle diameter of 10 μmφ or less. The lower limit of the average particle diameter is preferably 0.1 μmφ. If the particle size is small, that is, less than 0.1 μm, especially less than 0.01 μm, secondary agglomeration is likely to occur when compounded in PET that serves as a matrix, and not only the effect as a nucleating agent is impaired, but also a molded product by agglomerates. However, it has the drawback of deteriorating the appearance and quality. On the other hand, particles having a particle size of more than 10 μm, especially 20
Those exceeding μm are not suitable because they have a low crystallization promoting effect. In addition, the blending amount is required to be 0.1 to 10% by weight in each layer, preferably 0.3 to 7% by weight, and particularly 0.5 to
5% by weight is preferred. If the blending amount is less than 0.1%, the heat treatment temperature for crystallizing the same as the crystallization rate of the unmodified PET must be increased and the heat treatment time must be lengthened, which makes it difficult to remove from the mold. It is not suitable because it reduces productivity. On the other hand, when the compounding amount is increased, the ultimate crystallinity at the time of thermoforming tends to be high and the impact resistance tends to be lowered, and at a certain amount or more, a large improvement in crystallization rate is not seen. Further, since the formation of the vagina at the time of thermoforming becomes poor and the range of molding conditions becomes narrow, it is preferable that the compounding amount is suppressed to 10% by weight or less.

The content of the inorganic fine particles in the inner layer is preferably about the same as the content of the inorganic fine particles in the surface layer, and the content of the inorganic fine particles in the inner layer (wt%) / (the content of the inorganic fine particles in the surface layer (wt%) )) Is in the range of 0.5 to 1.5. The lower limit is preferably 0.6, more preferably 0.7, even more preferably 0.8, particularly preferably 0.9, and the upper limit is preferably 1.4, more preferably 1.3, still more preferably 1. 0.2, particularly preferably 1.1. Furthermore, it is preferable to use the same type of inorganic fine particles for the inner layer and the surface layer. Due to these, the characteristics of both layers can be made close to each other, and there is no delamination or curling when formed into two layers,
Further, it is possible to easily manufacture a sheet having stable quality even when both ends of the sheet, which are generated as dust during sheet molding, or a defective sheet molding is added.

The polyolefin resin used in the present invention preferably has a density of 0.91 g / cm ³ or less, a melt index (MI) of 10 g / 10 min or more, or both. Examples of the polyolefin resin include high-density polyethylene, branched low-density polyethylene, linear low-density polyethylene, ultra-low-density polyethylene, polypropylene, ethylene-propylene copolymer, maleic acid-modified polyethylene, vinyl acetate-ethylene copolymer, and acrylic. Examples thereof include ethyl acid-ethylene copolymer, ethylene-propylene copolymer, glycidyl methacrylate-ethylene copolymer, glycidyl methacrylate-ethyl acrylate-ethylene copolymer and the like. These may be used alone or in combination of two or more.

The amount of polyolefin resin used in the polyester sheet of the present invention is 0.5 with respect to the inner layer.
It is preferably from 10 to 10% by weight. The lower limit is preferably 1% by weight or more, more preferably 1.5% by weight or more, and particularly preferably 2% by weight or more. The upper limit of the polyolefin resin is preferably 10% by weight or less. By adjusting the amount of the polyolefin resin to the above-mentioned amount, the obtained container has excellent impact resistance, and also has excellent punching property after punching into a sheet and has a beautiful appearance. That is, the amount of polyolefin resin is 10
If the content exceeds 10% by weight, the punching property becomes poor, and a phenomenon in which sheet fragments that have not been sufficiently cut remain on the cut surface is a cause of poor appearance. In addition, an unpleasant odor peculiar to the polyolefin resin is generated, which is not preferable.

The polyolefin resin is not substantially contained in the surface layer. The term "substantially free from" means here.
It does not necessarily mean that it is not contained at all, and may be contained in a very small amount so as not to cause mold stains. The specific content that is allowed to be contained varies depending on the type of polyolefin, but it is less than 0.2% by weight, preferably less than 0.1% by weight, and more preferably less than 0.05% by weight.

To the multilayer polyester sheet of the present invention, any known crystal nucleating agent other than polyolefin and inorganic fine particles, for example, an organic nucleating agent such as PBT oligomer, sodium benzoate and sodium stearate can be added. The amount of these crystal nucleating agents added is 5% by weight.
It is the following and is appropriately set according to the type of nucleating agent. It should be noted that a step of reusing both ends of the cut-off sheet for the layer B may be included in the sheet production. In that case, layer B
The crystal nucleating agent existing in the layers other than is mixed in the layer B,
The amount of the mixed nucleating agent may be included in the above addition amount.

In the present invention, it is preferable that the surface layer further contains a wax, and further that the inner layer also contains a wax. The purpose of the wax used is to eliminate the roughening of the surface of the sheet first, and then to more finely disperse the inorganic particles acting as a crystal nucleating agent in the polyester, rather than adding the inorganic particles alone. This is to improve the effect. Recently, environmental hormones have been regarded as a problem, and among various waxes, waxes that are less dangerous and harmful to the human body and have low environmental impact are desired. A biodegradable wax is useful in that respect. Specific examples of the biodegradable wax include montan wax, carnauba wax, castor wax, candelia wax, vegetable wax such as rice bran wax, animal wax such as beeswax, hydrocarbon wax such as natural paraffin, stearic acid, etc. Fatty acid waxes, stearic acid amide, palmitic acid amide, methylene bis stearamide, ethylene bis stearamide,
Fatty acid amide wax such as oleic acid amide and esyl acid amide, ester lower wax of fatty acid, polyhydric alcohol ester of fatty acid, fatty acid polyglycol ester, etc., alcohol wax such as cetyl alcohol and stearyl alcohol , Metal soaps derived from fatty acids having 12 to 30 carbon atoms, and the like. Among these, plant waxes and animal waxes are preferable, and montan waxes are particularly preferable. However, the wax used to reach the present invention is not particularly limited.

The reason why the montan wax is used as a particularly preferable wax used in the present invention is that it satisfies the food hygiene requirements in response to the demands of the society and that the volatility at the time of production and processing is high. It was selected as a wax with little and no odor. A particularly desirable montan wax is a partially saponified montan ester wax.

The content of wax is 0.0 in each layer.
1 to 1.0% by weight is preferable, and the lower limit is 0.05% by weight. The upper limit is more preferably 0.
It is 5% by weight. The wax content of the inner layer and the surface layer is preferably about the same, and the (wax content of the inner layer (wt%)) / (wax content of the surface layer (wt%)) is 0.7.
Is preferably in the range of 1.3 to 1.3, the lower limit is 0.8,
Furthermore, 0.9 is desirable, the upper limit is 1.2, and further 1.1 is desirable. Furthermore, it is preferable to use the same type of wax for the inner layer and the surface layer. By these, the characteristics of both layers can be made close to each other, and a sheet of stable quality can be easily manufactured.

The polyester sheet of the present invention may be blended with various polymers or additives according to the purpose to obtain a composition. Examples of the polymer include polyamide-based polymers, polyester elastomers and other polyester-based polymers, polystyrene-based polymers, and polyacrylic-based polymers. As the additives, known hindered phenol-based, sulfur-based, phosphorus-based, amine-based antioxidants, hindered amine-based, triazole-based,
Compounds having reactive groups such as benzophenone-based, benzoate-based, nickel-based, salicyl-based light stabilizers, antistatic agents, lubricants, molecular regulators such as peroxides, epoxy-based compounds, isocyanate-based compounds, carbodiimide-based compounds, etc. , Metal deactivators, organic and inorganic nucleating agents, neutralizing agents, antacids, antibacterial agents, optical brighteners, fillers, flame retardants, flame retardant aids, organic and inorganic pigments, dyes Etc. can be added.

The multilayer polyester sheet of the present invention is usually composed of layer A (outermost layer in container): layer B: layer A (outermost layer in container). The ratio is layer A: layer B: layer A = 0.01: 9.98: 0.0
It is preferably 1 to 3: 4: 3. Number of layers is usually 3
Although it is a layer, it may be, for example, 5 layers or 7 layers as long as the resin composition of the layer A is located on both outermost layers, and the thickness ratio of the 3 layers in that case is in accordance with the above thickness ratio, The thickness ratio of the newly added layer is set to an arbitrary thickness necessary for expressing the effect.

The multilayer polyester sheet of the present invention may be composed of two layers, layer A and layer B. In this case, it is necessary to dispose at the time of molding so that the layer composed of the resin composition described as the layer A in this specification comes into contact with the molding die. If they are arranged in reverse, the polyolefin resin is transferred to the mold during vacuum molding or pressure molding, for example, which causes stains on the mold.

Further, the multilayer polyester sheet of the present invention may contain one or more layers other than the above-mentioned layers A and B. The resin composition used in the layers other than the two layers is not particularly limited, but examples thereof include CHDM copolymer polyester, polyester elastomer, PET, and isophthalic acid copolymer P.
Resins such as ET and mixtures thereof can be used.

The polyester sheet of the present invention is produced by a usual coextrusion method. Further, the sheet is processed into a container such as a tray by molding such as pressurization, vacuum and compression.

The crystallinity of a molded container or the like is preferably 10 to 40%, more preferably 20 to 35%. If the crystallinity is less than 10%, sufficient heat resistance of the container cannot be obtained, and if it is more than 40%, the container is overcrystallized and impact resistance is significantly lowered.

[0035]

The present invention will be described in more detail below with reference to Examples and Comparative Examples, but the present invention is not limited thereto. The main methods for measuring physical properties are as follows. (1) IV: Phenol / tetrachloroethane = 60
The measurement was performed at a temperature of 30 ° C. using a mixed solvent of / 40 (weight ratio).

(2) Dripping during preheating: The sheet was preheated with a vacuum pressure air forming machine TVP-33 type manufactured by Sanwa Kogyo Co., Ltd. with a heater output set to 90%, and the heater temperature was set to about 525 ° C.
And Under this condition, the sheet was heated for a certain period of time, and the amount of the sheet drooping was visually evaluated for its size. Those with a small amount of sag were marked with ◯, those with a large amount of sagging were marked with x, and the middle was marked with Δ.

(3) Mold deciding ability: With a vacuum pressure air molding machine TVP-33 type manufactured by Sanwa Kogyo Co., Ltd.
Vacuum molding was performed using 20 cc) to obtain a container. The sheet is preheated with the heater output set to 90% and the mold temperature is 1
It was set to 80 ° C. The degree of molding of the container obtained at this time, particularly at the corners, was visually evaluated. A sample having the same shape as the mold was evaluated as ◯, a sample not having the sufficient mold shape was evaluated as x, and the middle was evaluated as Δ.

(4) Releasability: With a vacuum pressure molding machine TVP-33 type manufactured by Sanwa Kogyo Co., Ltd.
Vacuum molding was performed using 20 cc) to obtain a container. The sheet is preheated with the heater output set to 90% and the mold temperature is 1
It was set to 80 ° C. The ease of separation of the container obtained at this time from the mold was visually evaluated. The case where the container quickly detached from the mold was marked with ◯, the one that was difficult to separate was marked with x, and the middle was marked with Δ.

(5) Punchability: A container obtained by vacuum molding using a vacuum pressure molding machine TVP-33 manufactured by Sanwa Kogyo Co., Ltd. using a mirror-finished mold (full capacity 320 cc) It was punched with a punching blade. The punched container was visually inspected for remaining cuts, and those with no cuts were rated as ◯, those with cuts as x, and the middle as Δ.

(6) Mold stains: A vacuum pressure molding machine TVP-33 manufactured by Sanwa Kogyo Co., Ltd. was used to perform vacuum molding using a mirror-finished mold (full pouring capacity 320 cc) to obtain a container. The sheet was preheated at a heater output of 90% and the mold temperature was 180 ° C. Molding was continuously performed 300 times, and the amount of polyolefin adhering to the mold surface was visually observed and evaluated. The case where the adhesion of the polyolefin was not recognized was evaluated as O, while the case where the adhesion of the polyolefin was recognized and the appearance of the container obtained by continuous molding was deteriorated was evaluated as X, and the middle was evaluated as Δ.

(7) Surface appearance: A vacuum pressure molding machine TVP-33 manufactured by Sanwa Kogyo Co., Ltd. was used to perform vacuum molding using a mirror-finished mold (full-flow capacity 320 cc) to obtain a container. The appearance of the obtained container surface was visually observed and evaluated. If the surface of the container is smooth and has a good appearance, the grade is ◯, while if the surface of the container is scratched or rough and the appearance is poor, the grade is × and the middle is △.
And

(8) Average particle size: liquid phase sedimentation type light transmission method (manufactured by Shimadzu Corporation, particle size distribution analyzer SA-CP3)
L) is the value of the cumulative amount of 50% by weight read from the cumulative particle size distribution curve.

The polyester resin, polyolefin resin and polyolefin resin used are as follows. PET: PET manufactured by Toyobo Co., Ltd. IV = 1.00 g / dl
Resin MICEL-TONE: Hayashi Kasei Co., Ltd. MICEL-
TONE: Average particle diameter = 1.4 μmφ # 5000S: Hayashikasei Co., Ltd. MICRON WHI
TE # 5000S: average particle size = 2.8 μmφ # 5000B: MICRON WHI manufactured by Hayashi Kasei Co., Ltd.
TE # 5000B: Average particle size = 7.7 μmφ PK-C: Hayashi Kasei Co., Ltd. TALCAN PAWDE
R PK-C: Average particle size = 11.0 µm UF 230: Linear low density polyethylene Novatec LL (UF230) manufactured by Nippon Polychem KK: Density = 0.9
21 g / cm3, MI = 1.1 g / 10 min VL800: Sumitomo Chemical Co., Ltd. special soft polyolefin Excellen VL (VL800): Density = 0.90
5 g / cm3, MI = 20 g / 10 min UJ790: linear low density polyethylene Novatec LL (UJ790) manufactured by Nippon Polychem Co., Ltd .: density = 0.9
28 g / cm3, MI = 50 g / 10 min Luwax OP: Montane wax (Luwax OP) manufactured by BSF Japan Co., Ltd .: melting point = 8
4 to 94 ° C

Examples 1 to 9 and Comparative Examples 1 to 3 Using each of the above resins, a homemade sheeting machine was used.
A 3-layer sheet having a thickness of 6 mm was obtained. The layer ratio is Layer A: Layer B:
Layer A was set to 1.6: 6.8: 1.6. The barrel temperatures during sheet formation were all 290 ° C. Next, using these sheets, vacuum pressure molding machine TPV- manufactured by Sanwa Kogyo Co., Ltd.
A 33-type tray container having a full injection capacity of 320 cc was obtained. The sheet was preheated at a heater output of 90% and the mold temperature was 180 ° C. Each sheet was evaluated for mold stains based on the evaluation method described above. Sheet layer A and layer B
The resin compositions and the evaluation results of are shown in Tables 1 and 2 below.

[0045]

[Table 1]

[0046]

[Table 2]

The numbers in the table represent% by weight of each component.

It can be seen from Tables 1 and 2 that the multilayer polyester sheets described in Examples 1 to 9 do not cause mold stains. In addition, in Examples 1 to 6, the moldability, releasability, punchability, and surface appearance at the time of molding were good, and Examples 7 to
In No. 9, some deterioration in quality was observed, but it was at a usable level. On the other hand, Comparative Examples 1 and 2 were inferior in moldability and releasability including sagging during preheating. In Comparative Example 2, slight delamination was observed during punching. In Comparative Example 3, mold stains were observed.

[0049]

As is apparent from Tables 1 and 2, the molded product obtained from the multilayer polyester sheet of the present invention composed of the polymer having the specific composition as described above has solved mold stains during molding. Therefore, the multilayer polyester sheet of the present invention,
It is suitable for obtaining molded products such as trays that require properties such as heat resistance, and is a major contribution to the industrial world.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hara Atsushi             2-1-1 Katata, Otsu City, Shiga Prefecture Toyobo             Koki Co., Ltd. F term (reference) 4F100 AJ11 AK03A AK41A AK41B                       AK42A AK42B AK63 BA02                       BA07 BA16 BA25 CA23A                       CA23B DE01A DE01B GB15                       GB23 JA06A JA13A JJ03                       JL06 YY00A YY00B

Claims (6)

[Claims] 1. A surface layer containing a polyester resin and inorganic fine particles and substantially not containing a polyolefin resin, and an inner layer containing a polyester resin, inorganic fine particles and a polyolefin resin, wherein the content of the inorganic fine particles in the inner layer ( Weight%)) / (content of inorganic fine particles in surface layer (weight%))
Is in the range of 0.5 to 1.5. 2. The average particle size of the inorganic fine particles is 10 μmφ
The multilayer polyester sheet according to claim 1, wherein: 3. A polyolefin resin that satisfies at least one of a density (ρ) of 0.91 g / cm ³ or less and a melt index (MI) of 10 g / 10 min or more. The multilayer polyester sheet according to claim 1 or 2. 4. The multilayer polyester sheet according to claim 1, wherein the surface layer has a thickness of at least 10 μm. 5. The multilayer polyester sheet according to any one of claims 1 to 4, wherein the polyester is a polyester whose main repeating unit is ethylene terephthalate. 6. A molded product, which is molded from the multilayer polyester sheet according to any one of claims 1 to 5.