JPH081766A - Deeply drawn thermoformed polyester vessel - Google Patents

Abstract

PURPOSE:To provide a deeply drawn polyester vessel in which thermoformability is excellent and particularly transparency and irregular thickness of the vessel are improved. CONSTITUTION:A polyester laminate is formed of a layer (A) made of polyester obtained by condensation polymerizing dicarboxylic acid ingredient mainly containing terephthalic acid and a glycol ingredient containing 0-90mol% of ethylene glycol and 10-100mol% of 1,4-cyclohexanedimethahol and having an intrinsic viscosity of 0.5-0.90, and a layer (B) made of polyester obtained by condensation polymerizing terephthalic acid and ethylene glycol and having an intrinsic viscosity of 0.5-0.75. A polyester vessel is obtained by laminating at least the layer (A) on one side surface and deep drawing and thermoforming a sheet having the layer (A) of a range of 1-30% of the entire thickness of the sheet at a draw ratio of 0.8 or more.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deep-drawn polyester container which has good thermoformability and in particular has improved transparency and uneven thickness of the container.

[0002]

2. Description of the Related Art A crystalline polyester resin represented by saturated polyester, particularly polyethylene terephthalate (hereinafter abbreviated as PET), is used as a sheet including fibers.
It is widely used as a polymer for films, but its excellent chemical resistance and low gas permeability make it a carbonated drink,
It has come to be applied to bottles for beverages such as juice and beer, cosmetic containers, and trays for food.

Among them, the amorphous polyester sheet called A-PET has attracted attention for its excellent recyclability, low pollution and food safety, and in recent years, its amount has rapidly increased as a packaging material replacing vinyl chloride and polystyrene. There is. This polyester sheet is used as a blister pack for food and medicine containers and miscellaneous goods by thermoforming,
Utilizing its excellent transparency, it is used as a clear case in which cosmetics, electric devices, etc. are put.

Conventionally, since such a saturated polyester sheet has crystallinity, if it is overheated during thermoforming, a whitening phenomenon due to crystallization occurs and the excellent transparency of A-PET is impaired. In particular, when thermoforming a cup-shaped deep-drawing container or a container having a complicated rib, it is necessary to sufficiently heat the sheet to be soft during thermoforming, and unmodified polyester may cause clouding or uneven thickness of the container. However, the problem is that the appropriate range of thermoforming conditions is very narrow, and improvement has been desired.

Conventionally, there have been many proposals for a method for improving the thermoformability of a polyester sheet. For example, as described in JP-A-51-81857 and JP-A-51-38335, there is a method of copolymerizing a component that inhibits crystallinity to prevent crystallization during heating.

However, the method of copolymerizing a small amount of a component that impairs crystallinity has a low effect of improving thermoformability, and it is difficult to improve uneven thickness during deep drawing. Further, the thermoformability is improved by increasing the copolymerization component, but
-It is not preferable because the flexibility and impact resistance of PET are impaired.

[0007]

DISCLOSURE OF THE INVENTION The inventors of the present invention have made diligent studies to solve such conventional problems, and as a result, 1, on at least one surface of a polyester having an intrinsic viscosity of 0.5 to 0.75. A container obtained by deep drawing thermoforming a polyester sheet obtained by laminating a polyester having an intrinsic viscosity of 0.5 to 0.90, which is obtained by copolymerizing 4-cyclohexanedimethanol in a specific range, is originally A-PET. The present invention has been accomplished by maintaining the transparency and mechanical strength possessed by, having no uneven thickness and being extremely excellent in economic efficiency.

[0008]

That is, the present invention comprises (A) a dicarboxylic acid component containing terephthalic acid as a main component, 0 to 90 mol% of ethylene glycol and 10 to 100 mol% of 1,4-cyclohexanedimethanol. Polyglycol component is polycondensed and has an intrinsic viscosity of 0.5-
A polyester laminate comprising a polyester layer having a ratio of 0.90 and (B) a layer made of a polyester obtained by polycondensing terephthalic acid and ethylene glycol and having an intrinsic viscosity of 0.5 to 0.75. Then, a sheet in which the (A) layer is laminated on at least one side and the (A) layer is in the range of 1 to 30% of the total thickness of the sheet is subjected to deep drawing thermoforming with a drawing ratio of 0.8 or more. It is a polyester container obtained by.

The polyester used for the main layer of the present invention is P
Not to mention ET, a part of the terephthalic acid component is one or more other dicarboxylic acid components such as isophthalic acid, adipic acid, diphenylcarboxylic acid, diphenyletherdicarboxylic acid, diphenylsulfonedicarboxylic acid, sebacic acid, naphthalenedicarboxylic acid, etc. And a part of the ethylene glycol component is replaced with one or more other glycol components such as diethylene glycol, hexamethylene glycol, trimethylene glycol, propylene glycol, cyclohexanedimethanol, neopentyl glycol, butylene glycol, etc. Includes polyester.

The total proportion of the copolymerization components in the copolymerized PET is preferably 10 mol% or less based on the total acid components. Further, a compound having three or more functional groups or a monofunctional compound may be contained within the range considered to be substantially linear. Furthermore,
A heat stabilizer, a fluidity improver, an ultraviolet absorber, an antistatic agent, an antifogging agent and the like can be added to the polyester within a range that does not reduce the transparency. Further, when matting is required, a coloring agent such as titanium dioxide, calcium carbonate, iron oxide or carbon black may be contained.

The intrinsic viscosity is 60/40 at a weight ratio of 60/40.
When measured in a phenol / tetrachloroethane mixed solvent, the intrinsic viscosity is required to be 0.5 to 0.75, and particularly preferably 0.6 to 0.75. If it is less than 0.5, the mechanical strength of the container is insufficient, and especially the impact strength at low temperature is insufficient. Further, the sheet is drawn down during thermoforming, and uneven thickness and wrinkles are likely to occur in the molded product, which is not preferable. On the other hand, if the intrinsic viscosity exceeds 0.75, the raw material PET resin needs to be solid-phase polymerized, resulting in poor economy.

The copolymerized polyester to be laminated on the surface of the present invention comprises a dicarboxylic acid component containing terephthalic acid as a main component, 0 to 90 mol% of ethylene glycol and 10 to 100 mol% of 1,4-cyclohexanedimethanol. The amount of 1,4-cyclohexanedimethanol obtained by polycondensation of the following glycol component and copolymerized is preferably 25 to 35 mol%. If it is less than 10 mol%, the effect of improving impact resistance is small.

The ratio of cis and trans of 1,4-cyclohexanedimethanol used is not particularly limited, but it is 4: 6.
˜0: 10 is good in terms of impact strength. The intrinsic viscosity is required to be 0.5 to 0.90, particularly preferably 0.6
It is 0 to 0.90. When the intrinsic viscosity is lower than 0.50, the mechanical strength of the final product is insufficient, and especially the impact strength at low temperature is insufficient. Further, when the intrinsic viscosity of the surface layer is slightly higher than that of the main layer, a thermoformed product having good transparency, in which plug-assisted transfer marks and drag lines are less likely to occur in the thermoformed product, can be obtained.

Drawing ratio (ratio of container depth to container diameter)
When thermoforming a deep-drawing thermoformed product of more than 0.8 or a rib-shaped complex tray, it is necessary to make the sheet sufficiently soft during heating. With unmodified A-PET, the surface of the molded product is Is clouded. It is considered that this is because the oriented skin layer on the surface of the sheet during film formation crystallizes during heating during thermoforming, and it is possible to perform deep drawing only by laminating a copolyester of a specific composition only on the very surface layer of the sheet. It was found that the property and the fogging of the container were significantly improved.

The proportion of the copolyester laminated on the surface of the sheet in the whole sheet is 1 to 30%,
From the viewpoint of economy and stability of quality, 5 to 20% is preferable.
If it is less than 1%, it becomes difficult to make the skin layer uniform. On the other hand, if it exceeds 30%, not only the effect of further improving the thermoformability is small, but also a large amount of expensive copolyester is used, which is economically unfavorable.

The sheet thickness used for producing the present invention is not particularly limited, but is usually 50 to 3000 μm,
It is preferably 350 to 2000 μm.

The sheet can be obtained by melt-extruding with a usual extruder for polyester such as a single-screw extruder or a twin-screw vent extruder, and cooling the molten resin with a cooling drum. The sheet is preferably cooled as rapidly as possible in order to prevent a decrease in transparency due to crystallization, and the crystallinity of the main layer is preferably 10% by weight or less (density 1.348 g / cm ³ or less) and the sheet haze is preferably 5% or less.

In order to obtain the present invention, it is possible to use a known coextrusion device having a feed block die, a multi-manifold die and the like. Also, it can be manufactured by a known technique such as melt laminating or dry laminating,
Coextrusion is preferred because of the quality of the sheet.

Further, as a film forming method, there are a method of sandwiching and cooling between metal rolls (touch roll method), an electrostatic application method, an air knife method and the like. However, from the viewpoint of sheet glossiness and thickness uniformity, the touch roll is used. Method is preferred.

In-line recycling is carried out by crushing the ears that appear when the sheet is cut to a predetermined width during film formation and the skeleton part punched out of the container after thermoforming and returning it as a raw material.
It is generally used in ET, but in the present invention, it can be compounded into the main layer within a range that does not extremely reduce the intrinsic viscosity of the sheet.

The product of the present invention may be manufactured by any of vacuum forming, pressure forming, hot plate forming, plug assist forming, reverse draw forming, air slip forming, etc., or a combination of these methods. It doesn't matter.

[0022]

INDUSTRIAL APPLICABILITY The present invention maintains the original properties of A-PET such as transparency, mechanical properties, and recyclability, has no uneven thickness, and is extremely excellent in economic efficiency. Optimal for trays with complex ribs, blister packs, etc.

[0023]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.
In addition, each characteristic value measurement was performed according to the following methods.

(1) Intrinsic Viscosity A phenol / tetrachloroethane mixed solvent having a weight ratio of 60/40 was used and measured at a concentration of 1.0 g / dl and at 20 ° C.

(2) Haze of container The haze (haze value) of the container was measured by a method according to JIS-K-7105 using a haze meter NDH-20D manufactured by Nippon Denshoku Co., Ltd.

(3) Thermoformability A container having a diameter of 80 mm and a drawing ratio was produced by a vacuum forming machine with plug assist. The case where a perfect container was formed was evaluated as ○, the case where the shape was complete but the transparency was poor was evaluated as △, and the case where the shape was incomplete or caused uneven thickness was evaluated as ×.

(4) Width of thermoforming conditions The sheet surface temperature at which thermoforming can be completed was measured with a non-contact type infrared radiation thermometer. A sheet having a thermoformable sheet surface temperature range of 15 ° C. or more was evaluated as ◯, a sheet having a temperature of 10 ° C. or more and less than 15 ° C. was evaluated as Δ, and a sheet having a temperature of less than 10 ° C. was evaluated as x.

(5) Drop strength of container 20 in a cup-shaped container having a diameter of 80 mm and a depth of 80 mm
Evaluation was carried out by adding 0 g of water and closing the lid (mating lid) and dropping it from the height of 2.5 m onto the concrete surface. Those that did not crack at all were marked with O, those with a cracking probability of 10% or less were marked with Δ, and those with a cracking probability of more than 10% were marked with X.

Examples 1 to 2 and Comparative Examples 1 to 6 Melt extrusion was performed from a T die using a multi-layer extruder with a biaxial vent under conditions of 285 ° C. and a vacuum degree of a vent portion of 5 mmHg, and manufactured by a touch roll method. Membrane, 800 μm thick Table 1
A sheet having the composition shown in was obtained.

Then, the sheet was preheated to a temperature not lower than the glass transition temperature and not higher than the melting point, and the diameter of 80 mm × each drawing ratio (see Table 1) was measured by a vacuum molding machine with a plug assist equipped with a female mold whose temperature was adjusted to 45 ° C. A cup-shaped container was prepared and evaluated. The evaluation results are also shown in Table 1.

[0031]

[Table 1]

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Claims (1)

[Claims] 1. A dicarboxylic acid component containing (A) terephthalic acid as a main component, 0 to 90 mol% of ethylene glycol, and 10 to 1 of 1,4-cyclohexanedimethanol.
Polycondensation with a glycol component consisting of 00 mol%,
And a layer composed of a polyester having an intrinsic viscosity of 0.5 to 0.90 and (B) a layer composed of a polyester obtained by polycondensing terephthalic acid and ethylene glycol and having an intrinsic viscosity of 0.5 to 0.75. A polyester laminate constituted, wherein the (A) layer is laminated on at least one side, and the (A) layer has a thickness of 1 to 3 of the entire sheet.
A polyester container obtained by subjecting a sheet in the range of 0% to deep drawing thermoforming with a drawing ratio of 0.8 or more.