JPH0641330A - Thermoforming sheet and thermoformed article - Google Patents

Abstract

PURPOSE:To provide a thermoforming material having excellent formability and giving a formed article having excellent heat-resistance. CONSTITUTION:A polyethylene naphthalate is used as a thermoforming sheet enabling deep draw forming by applying vacuum, compressed air, etc., under heating. A thermoformed article is produced by the thermoforming of the sheet.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deep-drawable sheet for obtaining a molded article having excellent heat resistance, and a technique for obtaining the thermoformed article.

[0002]

2. Description of the Related Art It has been already practiced for a long period of time to prepare a thermoformed body using a sheet made of a thermoplastic resin and use it for a food container or the like.

Examples of the material constituting the sheet or thermoformed body used for such an application include polyvinyl chloride, polystyrene, polypropylene, polycarbonate and polyethylene terephthalate.

However, it is not yet known to use polyethylene naphthalate (hereinafter sometimes abbreviated as PEN) as a material for deep drawing under heating.

[0005]

OBJECT OF THE INVENTION The object of the present invention is to obtain a thermoformed article having excellent heat resistance, and therefore to obtain a forming sheet which can be subjected to deep drawing under heating.

[0006]

The present invention is to apply a sheet made of PEN to the conventionally known thermoforming. The inventors have found that a molded product obtained by thermoforming this PEN exhibits extremely excellent heat resistance, and arrived at the present invention.

The present invention is a thermoforming sheet made of polyethylene naphthalene dicarboxylate (sometimes abbreviated as polyethylene naphthalate).

The present invention will be described.

In the present invention, PEN means a polyester having naphthalene dicarboxylic acid, preferably naphthalene-2,6-dicarboxylic acid as a main acid component and ethylene glycol as a main glycol component, that is, all or most of repeating units ( Usually 90 mol% or more, preferably 95 mol% or more) is a polyester in which butylene naphthalene dicarboxylate is used.

Further, this polyester can be copolymerized with the following components within the range not impairing the physical properties. That is, as the acid component, an aromatic dicarboxylic acid other than naphthalenedicarboxylic acid, for example, phthalic acid, isophthalic acid, terephthalic acid, diphenyldicarboxylic acid, diphenyletherdicarboxylic acid, diphenoxyethanedicarboxylic acid, diphenylmethanedicarboxylic acid, diphenylketonedicarboxylic acid, Examples thereof include diphenyl sulfide dicarboxylic acid, diphenyl sulfone dicarboxylic acid, aliphatic dicarboxylic acid such as succinic acid, adipic acid, sebacic acid, alicyclic dicarboxylic acid such as cyclohexanedicarboxylic acid, tetralindicarboxylic acid and decalindicarboxylic acid.

As the glycol component, 1,4-butanediol, propylene glycol, trimethylene glycol, pentamethylene glycol, hexamethylene glycol, octamethylene glycol, neopentyl glycol, cyclohexanedimethanol, xylylene glycol, diethylene glycol, polyethylene glycol, Bisphenol A, catechol, resorcinol,
Examples thereof include hydroquinone, dihydroxydiphenyl, dihydroxydiphenyl ether, dihydroxydiphenylmethane, dihydroxydiphenyl ketone, dihydroxydiphenyl sulfide, dihydroxydiphenyl sulfone and the like.

Examples of the oxycarboxylic acid component include oxybenzoic acid, hydroxynaphthoic acid, hydroxydiphenylcarboxylic acid and ω-hydroxycaproic acid.

Further, trifunctional or higher functional compounds such as glycerin, trimethylpropane, pentaerythritol, trimellitic acid and pyromellitic acid may be copolymerized as long as the polyester does not substantially lose the molding performance.

Such a polyester can be obtained by polycondensing naphthalenedicarboxylic acid and / or a functional derivative thereof and butylene glycol and / or a functional derivative thereof by a conventionally known aromatic polyester production method. The concentration of the terminal carboxyl group of PEN used in the present invention is not particularly limited, but it is desirable that it is low.

The polyethylene naphthalate used in the present invention may contain a third component as long as the thermoformability of the sheet and the heat resistance of the thermoformed body are not impaired.

The third component is, for example, a flame retardant, a flame retardant aid, a fibrous additive, a plate-like additive, a powdery or granular additive, a stabilizer or a coloring agent.

Specific examples of these third components include, for example, bisphenol A type brominated polycarbonate oligomers, brominated epoxies, brominated polystyrenes as flame retardants.
Examples thereof include brominated imide and brominated diphenyl ether.

As the flame retardant aid, Sb ₂ O ₃ , xNa ₂
O · Sb ₂ O ₅ · yH ₂ O (x = 0 to 1, y = 0 to
4), Sb ₂ O _{4 and the} like.

Examples of the fibrous additive include glass fiber, carbon fiber, silica fiber, silica / alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, titanium fiber, and further stainless steel, aluminum, titanium, Inorganic fibrous substances such as metallic fibrous substances such as copper and brass can be used. A particularly representative fibrous filler is glass fiber or carbon fiber.

On the other hand, the powdery and granular fillers include carbon black, silica, quartz powder, glass beads, glass powder, calcium silicate, kaolin, talc, clay, diatomaceous earth, silicates such as wollastonite, iron oxides, and oxides. Examples thereof include oxides of metals such as titanium, zinc oxide and alumina, sulfates of metals such as calcium carbonate and barium carbonate, as well as silicon carbide, silicon nitride, boron nitride and various metal powders.

Examples of the plate-like filler include mica, glass flakes, various metal foils and the like.

In using these inorganic fillers, it is desirable to use a sizing agent or a surface treating agent, if necessary. Examples of this are functional compounds such as epoxy compounds, silane compounds, isocyanate compounds, silane compounds and titanate compounds. These compounds may be subjected to surface treatment or focusing treatment before use, or may be added at the same time when the materials are adjusted.

Examples of the stabilizer include phosphorus-based stabilizers such as phosphoric acid, phosphorous acid, trimethyl phosphate, and trimethyl phosphite, and hindered phenol-based stabilizers.

Examples of colorants include carbon black, graphite, titanium oxide, zinc sulfide, and various dyes and pigments.

The additives to be added as the third component are not limited to one type, but two or more types may be added as long as they do not impair the thermoformability of the sheet of the present invention or the practical properties of the thermoformed article of the present invention. Good.

The third component may be directly supplied to the extruder at the time of forming the sheet, but it is also supplied to the extruder for granulation together with the polyethylene naphthalate, and pellets or master pellets in which the third component is once blended. Alternatively, a method may be used in which the sheet is prepared and mixed as it is or with a predetermined amount of polyethylene naphthalate to supply the sheet to an extruder.

As a method of forming a sheet from polyethylene naphthalate, a generally known method of forming a thermoplastic resin into a sheet can be applied.

For example, polyethylene naphthalate is first dried with hot air or vacuum at a temperature of 100 to 250 ° C.,
Then, the polymer is supplied to an extruder and melted at a melting temperature of the polymer to a melting temperature + 50 ° C., filtered with a filter as necessary, and extruded into a sheet through a die.

The sheet extruded in the molten state is immediately moved onto a cooling drum to be rapidly cooled.

After coming into contact with the cooling drum, the sheet is brought into close contact with the drum. Examples of the method include pressure bonding with an auxiliary roll, close contact with a drum by a so-called electrostatic contact method in which static electricity is charged on a sheet, or melting between two cooling drums adjacent in parallel. Means such as a so-called banking system for supplying the sheet in the state can be used.

The temperature of the cooling drum is not particularly limited as long as the sheet is obtained in a substantially amorphous state, but preferably the dew point of the atmosphere around the cooling drum to 100.
It is in the range of ° C.

The sheet thus obtained is subjected to edge trimming if necessary, wound into a roll shape, and further slitted as necessary to adjust the sheet width, or cut into a required length. The product is made into an intermediate product by means such as stacking it into sheets and then stacking them.

Next, a method for obtaining a thermoformed product using the sheet of the present invention will be described.

As a method for obtaining a thermoformed body, a generally known vacuum forming method, pressure forming method, vacuum pressure forming method, or the like is used, and auxiliary means such as plug assist can be added if necessary. Is.

The plug-assisted vacuum pressure air method will be described as an example. First, a sheet made of polyethylene naphthalate is preheated by means such as an infrared heater and a hot plate heater. Subsequently, a sheet-shaped plug (or male type) heated to the sheet as needed, for example, a female type in the shape of a tray or a cup was brought close to the sheet, and heated at the same time as needed, was sandwiched between the sheets. However, the sheet is brought closer to and in contact with the sheet from the opposite surface, and at the same time, suction is made from the pores provided in the female die, and compressed air is supplied from the pores provided in the plug to bring the sheet into close contact with the female die.

Regarding the positional relationship between the seat, the female die and the plug, in the case of the batch type method, the seat is fixed, and the female die and the plug approach or retreat from the top and bottom or the left and right with respect to the seat. On the other hand, in the case of the continuous forming method, a continuous sheet is intermittently moved and supplied between the female mold and the plug that approach and retract from the upper and lower sides or the left and right sides. That is, a method is used in which the unmolded part is newly moved into the system while the molded part is removed from the mold and moved out of the thermoforming system. The molded sheet is commercialized by cutting out only the necessary parts.

The thermoforming mold may be a single mold, but a multiple mold capable of simultaneously molding a large number of products of the same mold may be used.

[0038]

[Application] The sheet of the present invention is suitable for producing a thermoformed article having excellent heat resistance. Further, for example, a tray or cup-shaped thermoformed article produced by using the sheet is used for foods, beverages or Used as a packaging container for industrial products,
In particular, food that is distributed in a cold state can be directly placed on a table without being deformed even if it is directly put in, for example, an microwave oven or a microwave oven and heated.

In addition, the thermoformed product of the present invention can be used as an electric component, an electronic component, an automobile component, a mechanical component, or an element constituting these components by recognizing its excellent heat resistance. It can also be used for packaging of these industrial parts.

[0040]

EXAMPLES The present invention will be described in more detail with reference to the following examples. The intrinsic viscosity (sometimes abbreviated as IV) of the polymer described in this Example (and Reference Example) is a value obtained by dissolving the polymer in orthochlorophenol and measuring at 35 ° C.

Three kinds of polyethylene naphthalate polymers having different IVs were respectively hot-air dried at 180 ° C. for 3 hours, fed to an extruder and melted, and further extruded on a casting drum into a sheet form, and then allowed to stand. The film was brought into close contact with the casting drum by the electric contact method and then rapidly cooled.

All the obtained sheets were 0.3 mm.

Then, thermoforming was performed using the sheet.

The thermoforming machine used in this example is a FC-1APA-W type vacuum pressure air forming machine manufactured by Asano Laboratory, and the forming machine has a long side of the upper opening rectangular portion of 12 cm and a short side. A tray-shaped mold having a side of 5.5 cm, a depth of 2 cm, a long side of the bottom rectangular portion of 10 cm, and a short side of 3.5 cm was mounted.

Further, an assist plug having a shape corresponding to the mold was also attached.

Next, the heat resistance of the thermoformed product prepared was examined. In the method, salad oil heated to each temperature was poured into the thermoformed product, and after 5 minutes, it was discharged and the shape of the thermoformed product was observed.
The results are summarized in Table 1.

[0047]

[Table 1]

As a reference example, an experimental example of polyethylene terephthalate, which is commonly used as a material for thermoformed articles, is also shown as a reference example. The experimental conditions are the same as for polyethylene naphthalate.

As is clear from the results shown in Table 1, the thermoforming sheets made of polyethylene naphthalate show excellent moldability, and the thermoformed sheets made of the sheets all show excellent heat resistance. It was

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display area C08L 67:00

Claims (3)

[Claims] 1. A thermoplastic resin sheet capable of deep drawing under heating, wherein the resin sheet comprises polyethylene naphthalene dicarboxylate. 2. A thermoformed body obtained by thermoforming using the resin sheet according to claim 1. 3. A thermoformed article, wherein the polyethylene naphthalene dicarboxylate of claim 1 is polyethylene-2,6-naphthalene dicarboxylate.