JP2011126544A - Thermoformed container - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polypropylene-based thermoformed container durable to retort processing and made by deep drawing. <P>SOLUTION: The thermoformed container has a deep drawing structure having a ratio of depth/aperture of the container of not less than 1, molded by a solid phase pressure forming using a polypropylene-based sheet comprising a propylene-based resin composition satisfying the following requirements (i) and (ii). The requirement (i) the melt flow rate (MFR) (temperature: 230°C and load: 2.16 kg) is 0.2-1.5 g/10 min, and the requirement (ii) the melting peak temperature is not less than 165°C measured by a differential scanning calorimeter (DSC). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a thermoformed container, and more particularly, to a deep-drawn thermoformed container that can withstand retort processing, and to a thermoformed container obtained by solid-phase pressure forming a polypropylene sheet at a temperature below the melting peak temperature. .

  Conventionally, containers using thermoplastic resins such as polystyrene, polyethylene terephthalate, and polypropylene have been manufactured. Among thermoplastic resins, the propylene-based resin composition is excellent in heat resistance, rigidity, impact resistance, or hygiene, and thus is suitably used as a container for foods, and in particular, has high heat resistance. The range of use has expanded to the range-up containers in the required microwave oven, containers that require high-temperature filling, and the like.

As a food container, a container having a long main body for storing contents relative to the caliber of the container, that is, a so-called deep-drawn container is effective in that it can have a larger internal capacity than the caliber and is easy to hold.
Such a deep drawn container may be formed by injection molding. Injection molding is suitable for deep-drawn container molding because it can be easily molded into a desired shape depending on the mold used. However, the injection molding has problems that the mold cost is high when a large number of pieces are taken, the production speed is slower than that of a thermoformed container, and it is difficult to produce a thin molded product.

On the other hand, after extruding a thermoplastic resin into a sheet, the sheet is reheated to obtain the desired container. Thermoforming methods such as vacuum forming, vacuum pressure forming, and solid pressure forming are easy to mold and productivity. Since it is high, it is suitable for mass production and it is easy to obtain multi-layered products.
However, the thermoforming method in which the container is formed in a state where the sheet is melted, such as vacuum forming or vacuum / pressure forming, is reheated to a temperature equal to or higher than the melting point, so that a deep drawn container having a large depth / caliber ratio is used. It is difficult to obtain and it is difficult to form a container that is valuable as a product.

  In recent years, packaging materials that can withstand high-temperature retort processing have been demanded in order to ensure food safety, and various film materials that have both heat resistance and sealing properties have been proposed (Patent Document 1). And Patent Document 2). On the other hand, various materials have been proposed for thermoformed containers from sheets (see Patent Document 3 and Patent Document 4), but they are satisfactory as retort heat-resistant sheet materials that can be formed into deep-drawn containers by solid-state pressure forming. There is a need for a deep-drawn thermoformed container that is not sufficient for retort processing.

JP 2006-150892 A JP 2006-307120 A JP 2006-282259 A JP 2008-207818 A

  An object of the present invention is to provide a thermoformed container having a deep-drawing structure that can be produced by pressure forming a polypropylene-based sheet at a temperature equal to or lower than the melting peak temperature in view of the above-described problems of the prior art. It is to provide.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor, when a polypropylene sheet made of a specific propylene-based resin composition is subjected to solid-state pressure molding at a temperature equal to or lower than the melting peak temperature, the heat resistance against retort treatment As a result, the present invention has been completed.

That is, according to the first invention of the present invention, in the thermoformed container obtained by solid-phase pressure molding using a polypropylene sheet, the main layer satisfies the following requirements (i) to (ii): There is provided a thermoformed container comprising a deep drawing structure having a ratio of depth / caliber of the container of 1 or more.
Requirement (i): Melt flow rate (MFR) (temperature 230 ° C., load 2.16 kg) is 0.2 to 1.5 g / 10 minutes Requirement (ii): Melt peak measured with a differential scanning calorimeter (DSC) Temperature is 165 ° C or higher

  According to a second aspect of the present invention, there is provided the thermoformed container according to the first aspect, further comprising an ethylene-vinyl alcohol copolymer layer or an MXD6 polyamide resin layer as a barrier layer. Is done.

  Furthermore, according to the third invention of the present invention, there is provided a thermoformed container according to the first or second invention, wherein the propylene resin composition contains an organic phosphate crystal nucleating agent. Is done.

The thermoformed container of the present invention can be widely applied to food containers, medical containers and the like because deformation of the container is very small even by retort processing.
In addition, the thermoforming container of the present invention uses a specific polypropylene-based sheet, and if the solid-phase pressure forming method in plug-assist molding is applied thereto, the retort can be achieved despite the difference in size and shape of the container. A container-like molded product with little deformation due to processing has an effect that it can be stably and easily molded in a high-speed cycle with a high yield.

The thermoforming container of the present invention is a thermoforming container obtained by solid-phase pressure forming using a polypropylene-based sheet, and the main layer of the sheet has the characteristics and properties shown in the following requirements (i) to (ii). A propylene-based resin composition is used, and the molded container has a deep drawing structure having a depth / caliber ratio of 1 or more.
Requirement (i): Melt flow rate (MFR) (temperature 230 ° C., load 2.16 kg) is 0.2 to 1.5 g / 10 minutes Requirement (ii): Melt peak measured with a differential scanning calorimeter (DSC) The temperature is 165 ° C. or higher. Hereinafter, the present invention will be sequentially described item by item.

1. Propylene-based resin composition In the present invention, a specific propylene-based resin composition (A) is used as the main layer of the material sheet to be thermoformed.
The propylene-based resin composition (A) has the characteristics and properties shown in the requirements (i) to (ii).
Requirement (i) Melt flow rate (MFR):
As shown in the requirement (i), the propylene-based resin composition (A) according to the present invention has a melt flow rate (MFR) measured at a temperature of 230 ° C. and a load of 2.16 Kg of 0.2 to 1.5 g / 10. It is characterized by minutes.
When the MFR is less than 0.2 g / 10 minutes, the melt fluidity is lowered and sheet forming becomes difficult. On the other hand, if the MFR exceeds 1.5 g / 10 minutes, the molding temperature at the time of molding the container decreases, the deformation of the container at the time of retort treatment increases, and the shrinkage rate increases. Among these, it is preferable that MFR is 0.4-1.0 g / 10min.

The melt flow rate (MFR) is a test condition in accordance with JIS K6921-2 “Plastics—Polypropylene (PP) molding and extrusion materials—Part 2: How to make test pieces and properties”. : A value measured at 230 ° C. and a load of 2.16 kgf.
The melt flow rate (MFR) of the propylene-based resin composition (A) can be prepared by a conventionally known method, and usually the temperature and pressure, which are polymerization conditions of the propylene-based resin composition (A), are adjusted. Or by controlling the amount of a chain transfer agent such as hydrogen added during polymerization.

Requirement (ii) Melting Peak Temperature The propylene-based resin composition (A) is characterized in that the melting peak temperature measured by a differential scanning calorimeter (DSC) is 165 ° C. or higher. When the melting peak temperature is less than 165 ° C., the rigidity and heat resistance of the container are lowered, and the molding temperature during the molding of the container is lowered, so that the deformation of the container during the retort treatment is increased. The melting peak temperature is more preferably 167 ° C. or higher.
In order to adjust the melting peak temperature, it can be easily adjusted by controlling the amount of copolymerization monomer such as α-olefin supplied to the polymerization reaction system.
The specific measurement of the melting peak temperature was performed using a Seiko DSC, taking 5.0 mg of sample and holding it at 200 ° C. for 5 minutes, followed by crystallization at a rate of temperature decrease of 10 ° C./min to 40 ° C. The melting peak temperature when melted at a heating rate of 10 ° C./min was defined as the melting peak temperature (unit: ° C.).

2. Production method of propylene-based resin composition (A) The polymerization catalyst for producing the propylene-based resin composition (A) used in the present invention includes a Ziegler-Natta type catalyst, a metallocene catalyst, and the like. However, in order to obtain a polymer having a melting peak temperature of 165 ° C. or higher, a magnesium chloride-supported Ziegler-Natta type catalyst is preferable.
As a polymerization method of the propylene-based resin composition (A), various general-purpose processes such as a slurry method, a bulk method, a solution method, and a gas phase method can be applied. These polymerization reactions may be used not only in a single reactor but also in a plurality of stages, and a plurality of polymerization methods may be used in combination such as a bulk method-gas phase method.
Examples of the propylene resin composition (A) include a homopolymer of propylene, a random copolymer of propylene and an α-olefin, a block copolymer containing a copolymer rubber component of propylene and an α-olefin, and the like. However, in order to obtain a polymer having a melting peak temperature of 165 ° C. or higher, a homopolymer of propylene is preferable.

Examples of the α-olefin used in the propylene copolymer include ethylene, butene-1, pentene-1, hexene-1, 4-methyl-pentene-1, octene-1, and the like. Alternatively, two or more multi-component copolymers may be used.
Specifically, propylene-ethylene copolymer, propylene-butene-1 copolymer, propylene-ethylene-butene-1 copolymer, propylene-ethylene-pentene-1 copolymer, propylene-pentene-1 copolymer Examples thereof include various binary or ternary copolymers such as a polymer, a propylene-hexene-1 copolymer, a propylene-4-methyl-pentene-1 copolymer, and a propylene-octene-1 copolymer.
The homopolymer of propylene may be a copolymer obtained by copolymerizing a small amount of an α-olefin. In this case, it is sufficient that the proportion of the α-olefin is about 0.1 to 1 mol%.

  Further, the catalyst used for the polymerization is preferably a catalyst subjected to a prepolymerization treatment in which a small amount of the olefin is brought into contact with the catalyst. By performing the prepolymerization treatment, gel formation can be prevented when the main polymerization is performed. The reason is considered to be that long-chain branches can be uniformly distributed among the polymer particles when the main polymerization is performed, and the melt physical properties can be improved thereby.

The olefin used in the prepolymerization is not particularly limited, but propylene, ethylene, 1-butene, 1-hexene, 1-octene, 4-methyl-1-pentene, 3-methyl-1-butene, vinylcycloalkane, Styrene and the like can be exemplified. The olefin feed method may be any method such as a feed method for maintaining the olefin at a constant speed or in a constant pressure state, a combination thereof, or a stepwise change. The prepolymerization temperature and time are not particularly limited, but are preferably in the range of −20 ° C. to 100 ° C. and 5 minutes to 24 hours, respectively. The amount of prepolymerization is preferably 0.01 to 100, more preferably 0.1 to 50 with respect to the catalyst component. Moreover, a catalyst component can also be added or added at the time of prepolymerization. It is also possible to wash after the prepolymerization.
In addition, a method of coexisting a polymer such as polyethylene or polypropylene, or a solid of an inorganic oxide such as silica or titania, at the time of contacting or after contacting each of the above components is also possible.

2-1. Use of Catalyst / Propylene Polymerization As the polymerization mode, any mode can be adopted as long as the olefin polymerization catalyst containing the catalyst component and the monomer efficiently contact each other.
Specifically, a slurry method using an inert solvent, a so-called bulk method, a solution polymerization method, or a substantially liquid solvent without using an inert solvent as a solvent. A gas phase method can be used. Further, a method of performing continuous polymerization or batch polymerization is also applied. In addition to single-stage polymerization, it is possible to carry out multistage polymerization of two or more stages.

In the case of slurry polymerization, a saturated aliphatic or aromatic hydrocarbon such as hexane, heptane, pentane, cyclohexane, benzene, toluene or the like is used alone or as a mixture as a polymerization solvent.
The polymerization temperature is usually 0 ° C. or higher and 150 ° C. or lower. In particular, when bulk polymerization is used, 40 ° C. or higher is preferable, and 50 ° C. or higher is more preferable. The upper limit is preferably 80 ° C. or lower, more preferably 75 ° C. or lower.
Furthermore, when using vapor phase polymerization, 40 degreeC or more is preferable, More preferably, it is 50 degreeC or more. The upper limit is preferably 100 ° C. or lower, more preferably 90 ° C. or lower.
The polymerization pressure is 1.0 MPa or more and 5.0 MPa or less. In particular, when bulk polymerization is used, the pressure is preferably 1.5 MPa or more, more preferably 2.0 MPa or more. The upper limit is preferably 4.0 MPa or less, more preferably 3.5 MPa or less.
Furthermore, when using vapor phase polymerization, 1.5 MPa or more is preferable, and 2.0 MPa or more is more preferable. The upper limit is preferably 2.5 MPa or less, more preferably 2.0 MPa or less.

Further, hydrogen can be used as a molecular weight regulator and for the purpose of improving the activity. Hydrogen is used in a feed ratio of 0 to 1 mol% with respect to propylene, preferably 0.0001 mol% or more, and more preferably 0.001 mol% or more.
By changing the amount of hydrogen used, in addition to the average molecular weight of the polymer produced, the molecular weight distribution, the bias of the molecular weight distribution toward the high molecular weight side, very high molecular weight components, branching (amount, length, distribution) The melt physical properties such as melt tension and melt spreadability can be controlled.

In addition to the propylene monomer, copolymerization using an α-olefin having about 2 to 20 carbon atoms (excluding those used as a monomer) as a comonomer may be performed. The (total) comonomer content in the propylene-based resin composition is in the range of 0.1 mol% or more and 1 mol% or less, and a plurality of the above-mentioned comonomers can be used. Specifically, ethylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene.
Among these, in order to obtain the propylene resin composition (A) according to the present invention in a good balance between melt physical properties and catalytic activity, it is preferable to use ethylene at 0.5 mol% or less.
In order to obtain a polymer having particularly high rigidity, it is preferable to use ethylene so that ethylene contained in the polymer is 0.2 mol% or less, more preferably propylene homopolymerization. The propylene-based resin composition (A) is preferably a propylene homopolymer having a high melting peak temperature. As a specific brand, for example, trade name “Novatec PP” manufactured by Nippon Polypro Co., Ltd. is preferably exemplified.

3. Other compounding agents In the propylene-based resin composition (A) used in the present invention, other known polymers usually used for polyolefins can be blended in a proportion of 0 to 20% by weight.
Examples of the other polymer include propylene alone or a copolymer of propylene and another α-olefin, polymers such as low density polyethylene and high density polyethylene, and various thermoplastic elastomers.
Specifically, the propylene-based resin composition (A) is 80% by weight or more, and the remaining 0 to 20% by weight includes various general-purpose propylene (co) polymers, E-P-R, low density or high density. Materials such as resins such as polyethylene, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylate copolymer, various elastomers, elastomers, fillers and additives can be arbitrarily blended. These compounding materials are provided with characteristics that serve as a base material layer that is a main layer of the propylene-based resin composition (A).

In the propylene resin composition (A) used in the present invention, it is preferable that a crystal nucleating agent is blended in the propylene resin composition in order to improve the retort resistance.
The compounding amount of the crystal nucleating agent is in the range of 0.01 to 1 part by weight, preferably 0.02 to 0.8 part by weight, more preferably 0 to 100 parts by weight of the propylene-based resin composition (A). 0.04 to 0.5 parts by weight. When the blending amount of the crystal nucleating agent is less than this range, the effect of improving the retort resistance is hardly obtained, and when it exceeds this range, it is not preferable from the viewpoint of economy.
Examples of the crystal nucleating agent preferably used in the present invention include amide nucleating agents such as organic carboxylic acid metal salts, organic phosphoric acid metal salts, sorbitol derivatives, and rosin metal salts. Of these crystal nucleating agents, organophosphate metal salts are particularly preferred in terms of the effect of improving retort resistance.
A commercially available crystal nucleating agent can be used. For example, trade names Adeka Stub NA11 and NA21 manufactured by Adeka Company, trade name Gelall MD manufactured by Shin Nippon Rika Co., Ltd., and product names Mirad NX3988 and Mirad NX8000 manufactured by Milliken are listed.

The propylene-based resin composition (A) usually includes an antioxidant, a neutralizing agent, a light stabilizer, an ultraviolet absorber, an inorganic filler, an antiblocking agent, a lubricant, an antistatic agent, a metal deactivator, and the like. Various additives that can be used for polypropylene can be blended within a range that does not impair the object of the present invention.
Examples of antioxidants include phenolic antioxidants, phosphite antioxidants, and thio antioxidants, and examples of neutralizing agents include higher fatty acid salts such as calcium stearate and zinc stearate. Examples of the light stabilizer and the ultraviolet absorber include hindered amines, nickel complex compounds, benzotriazoles, and benzophenones.

4). Polypropylene-based sheet The polypropylene-based sheet used in the present invention is a sheet composed of a main layer using at least the propylene-based resin composition (A), and may have a multilayer structure of two or more layers. For example, even if a barrier sheet in which a barrier resin layer such as EVOH or PA and an adhesive layer are provided between the main layer and the innermost layer, the outermost layer has a design property such as a high gloss layer or a low gloss layer. It is also possible to arrange the layers.

In particular, in medical containers and food containers that perform retort treatment, it is preferable to use another layer structure with the barrier resin in order to prevent oxidative deterioration of the contents. The propylene-based sheet of the present invention comprises a main layer constituting a container body portion, an ethylene-vinyl alcohol copolymer (EVOH), MXD6 polyamide, polyvinyl alcohol, polyvinylidene chloride (PVDC), maleic anhydride-modified polypropylene, high impact. It is also possible to form a laminate having a so-called three-layer structure or four-layer structure in which various materials made of polystyrene (HIPS), amorphous polyethylene terephthalate, low-expanded polystyrene, and the like are stacked in consideration of gas barrier properties.
MXD6 polyamide is a polyamide obtained using metaxylylenediamine and adipic acid as main components. Of the above, the gas barrier layer is preferably ethylene-vinyl alcohol copolymer (EVOH) or MXD6 polyamide.

The thickness of the polypropylene-based sheet used in the present invention is preferably 0.3 to 4 mm, more preferably 0.5 to 3.5 mm, and particularly preferably 0.8 to 3 mm. If the thickness is much less than 0.3 mm, the rigidity of the container is impaired, and if the thickness is much more than 4 mm, sheet molding may be difficult.
Furthermore, the thickness ratio (barrier layer / main layer) of the barrier layer to the main layer of the polypropylene sheet used in the present invention is preferably 0.02 or more and 2 or less, and 0.04 or more and 0.15 or less. More preferably, it is 0.06 or more and 0.12 or less. When the thickness ratio between the barrier layer and the main layer is less than 0.02, the barrier resin may absorb water during the retort treatment and the barrier performance may be deteriorated. When it exceeds 2, the elongation unevenness of the barrier layer at the time of container molding may occur, and the commercial value of the container may be reduced.

Such a polypropylene sheet can be formed into a multi-layer polypropylene sheet using a feed block or a multi-manifold using an extruder provided with a plurality of dies usually used for forming polypropylene.
As a specific method for producing a polypropylene-based sheet, the propylene-based resin composition (A) is passed through a known monoaxial or biaxial screw extruder and extruded from a coat solder die into a sheet shape (inside It can be obtained by cooling and solidifying by pressing an air knife, an air chamber, a hard rubber roll, a steel belt, or a metal roll on the surface of the metal roll (where cooling water or oil circulates). It is also possible to cool and solidify both sides of the sheet with a steel belt.
Among such sheet cooling methods, a method using metal rolls and / or steel belts on both sides of the sheet is the most preferable method because a sheet surface with less surface irregularities, that is, a sheet having excellent transparency can be obtained. .

5). Thermoformed container The thermoformed container of the present invention has a deep drawing structure having a depth / caliber ratio of 1 or more, which is obtained by solid-phase pressure forming using a polypropylene sheet.
The thermoformed container of the present invention has a drawing ratio that is a ratio of the (maximum) depth to the bottom surface of the container body and the (maximum) width (bore diameter) of the container body, regardless of whether the container shape is square or round. Must be 1.0 or more, preferably 1.2 or more. A squeezing ratio of 1.0 or more is generally called a deep-drawn container and is obtained by plug-assisted solid-phase pressure molding, and has excellent container rigidity and impact strength. It is difficult to obtain a container with small deformation due to processing. However, according to the present invention, it is possible to easily obtain a container having a small deformation by retort processing.

Such a multilayer thermoformed container uses a polypropylene-based sheet, and the sheet is softened at a temperature equal to or lower than the melting peak temperature of the main layer, and is usually used for forming a polypropylene sheet, preferably by a plug-assisted solid-state pressure forming machine. Obtainable.
Examples of the heating method in such molding include indirect heating, hot plate heating, and hot roll heating. If molding is performed at a temperature exceeding the melting peak temperature of the sheet, the transparency, gloss, and thickness uniformity of the resulting multilayer thermoformed container are deteriorated, assist plugs are attached, and molding tends to be impossible.
In the present invention, such solid-phase pressure molding is plug-assisted molding at a temperature lower than the melting peak temperature of the propylene-based resin composition (A) of the main layer constituting the polypropylene-based sheet.

  When the plug assist thermoforming is performed below the melting peak temperature of the main layer made of the propylene-based resin composition (A), it is preferably heated at such a temperature that the melting peak temperature difference is in the range of 5 to 30 ° C. The main layer is softened, and then the assist plug is pushed down to form a polypropylene sheet into a container shape, and pre-shaped into a container shape by solid-phase pressure forming, and then the air pressure is applied to the pre-shaped portion. A deep-drawn container can be formed by adding the above and bringing the polypropylene sheet into close contact with the mold cavity surface.

6). Applications of thermoformed containers The thermoformed containers of the present invention are excellent in design and can be retort-treated, and therefore can be used for containers in various fields such as food containers, detergent containers, and medical containers. Can be widely used.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.
In Examples and Comparative Examples, various physical properties of the multilayer thermoformed container or its constituent components were measured and evaluated according to the following evaluation methods, and the following resins were used as the used resins (used materials). .

[1. Evaluation methods]
(1) Melt flow rate (MFR) [unit: g / 10 min]:
The propylene-based resin composition (A) is obtained by JIS K7210: 1999 “Method for testing plastic-thermoplastic melt mass flow rate (MFR) and melt volume flow rate (MVR)”, condition M (230 ° C., 2 .16 kg load).

(2) Melting peak temperature (Tm):
Using a DSC6200 manufactured by Seiko Instruments Inc., a 5 mg aluminum pan was filled with the propylene-based resin composition. The crystallization temperature (Tc) is obtained as the maximum crystal peak temperature (° C.) when the temperature is lowered to 20 ° C. and crystallized, and then the maximum melting peak temperature when the temperature is increased to 200 ° C. at 10 ° C./min. The melting peak temperature (Tm) was determined as (° C.).

(3) Container drawing ratio:
The outer diameter and depth of the mouth of the deep-drawn molded product were measured with calipers, and the ratio (depth / outer diameter) was taken as the drawing ratio.

(4) Container molding temperature:
The sheet surface temperature immediately before molding in the container molding machine was measured with a non-contact type radiation thermometer.

(5) Formability (plug adhesion):
Using the polypropylene-based sheet obtained in each example, the container was continuously formed for 30 minutes, and it was confirmed whether deposits on the plug were generated.
○: No adhesion ×: Adhesion occurs and molding is impossible

(6) Thermal retort property:
The obtained multilayer thermoformed container was treated in an oven at a predetermined temperature for 30 minutes, the volume before and after that was measured, and the volume shrinkage was measured.

[2. Materials used]
(1) Propylene-based resin composition EA9FT: (Nippon Polypro Propylene Polymer, the same shall apply hereinafter)
MFR = 0.4 g / 10 min, melting peak temperature 168 ° C.
FA9H:
MFR = 0.5 g / 10 min, melting peak temperature 167 ° C.
EA6A:
MFR = 1.9 g / 10 min, melting peak temperature 165 ° C.
EA9:
MFR = 0.5 g / 10 min, melting peak temperature 161 ° C.
EG8B:
MFR = 0.7 g / 10 min, melting peak temperature 145 ° C.

Example 1
The polypropylene sheet obtained by feeding the EA9FT pellets into an extruder with a screw diameter of 50 mm, heat melting and plasticizing at a resin temperature of 230 ° C., and extruding from a T-shaped die is mirror-finished with a surface temperature controlled at 60 ° C. A sheet having a width of 500 mm and an overall thickness of 2.0 mm was obtained by continuously taking it up at a speed of 1 m / min while being cooled and solidified with a metal cast roll.
Next, using this sheet, a thermoformed container (drawing ratio 1.4) having a diameter of 75 mmφ and a depth of 105 mm was formed by a solid-state pressure forming machine RDM50K (manufactured by Erich). The sheet temperature immediately before molding was 155 ° C.
Various evaluations described above were performed on this thermoformed container. The results are shown in Table 1.

(Example 2)
It implemented similarly to Example 1 except having used EA9H instead of EA9FT.
The evaluation results are shown in Table 1.

(Example 3)
Instead of EA9FT, the same procedure as in Example 1 was performed except that 0.1 part of Adeka Stub NA11 (manufactured by Adeka) was added to EA9H and pellets granulated with a single-axis granulator were used.
The evaluation results are shown in Table 1.

Example 4
It implemented like Example 1 except having used the dry blend product of EA9FT / EA6A = 50/50 instead of EA9FT. The evaluation results are shown in Table 1.

(Example 5)
The EA9FT pellets are introduced into an extruder with a screw diameter of 50 mm, EVOH pellets (BX6804B: manufactured by Nippon Synthetic Chemical Industry) are introduced into an extruder with a screw diameter of 40 mm, and an adhesive resin is added to another extruder with a screw diameter of 40 mm. (Modic P604V: manufactured by Mitsubishi Chemical Co., Ltd.), a polypropylene sheet obtained by extruding from a T-type die by heat melt plasticizing at a resin temperature of 230 ° C, and made of a mirror-finished metal whose surface temperature is controlled at 60 ° C Three types of materials: 500 mm wide, EVOH layer thickness 0.1 mm, adhesive resin thickness 0.1 mm each, and total thickness 1.6 mm while being cooled and solidified by sandwiching with a caster. A five-layer sheet was obtained. Next, using this sheet, a thermoformed container having a diameter of 75 mmφ and a depth of 80 mm was formed by a solid-state pressure forming machine RDM50K (manufactured by Erich).
Various evaluations described above were performed on this multilayer thermoformed container. The results are shown in Table 1.

(Example 6)
It implemented similarly to Example 5 except having used MXD6 nylon (S7007: Mitsubishi Gas Chemical Co., Ltd.) instead of EVOH. The evaluation results are shown in Table 1.

(Comparative Example 1)
It implemented similarly to Example 1 except having used EA6A instead of EA9FT.
The evaluation results are shown in Table 2.

(Comparative Example 2)
It implemented similarly to Example 1 except having used EA9 instead of EA9FT.
The evaluation results are shown in Table 2.

(Comparative Example 3)
It implemented similarly to Example 1 except having used EG8B instead of EA9FT.
The evaluation results are shown in Table 2.

(Comparative Example 4)
A container having a diameter of 95 mmφ and a depth of 80 mm (drawing ratio 0.84) was used in the same manner as in Comparative Example 1 except that a container having a diameter of 95 mmφ and a depth of 80 mm (drawing ratio 0.84) was used instead of the container having a diameter of 75 mmφ and a depth of 105 mm.
The evaluation results are shown in Table 2.

  As is clear from Table 1 and Table 2 above, in Examples 1 to 6 that satisfy all the configurations of the present invention, a thermoformed container with small deformation due to retort treatment was stably obtained by solid-phase pressure forming. On the other hand, in Comparative Examples 1 to 4 that do not satisfy the configuration of the present invention, the obtained thermoformed container is unstable in molding, undergoes large deformation during retort processing, has a small drawing ratio, and is inferior in commercial value. It was a thermoformed container.

  The multilayer thermoformed container of the present invention is a container that is excellent in design by solid-phase pressure forming and can be retorted, and thus can be widely used in the fields of food containers and beverage containers. Therefore, the industrial applicability is very large.

Claims (3)

In a thermoformed container obtained by solid-phase pressure molding using a polypropylene sheet, the main layer is made of a propylene resin composition that satisfies the following requirements (i) to (ii), and the ratio of the depth / caliber of the container is A thermoformed container having one or more deep drawing structures.
Requirement (i): Melt flow rate (MFR) (temperature 230 ° C., load 2.16 kg) is 0.2 to 1.5 g / 10 minutes Requirement (ii): Melt peak measured with a differential scanning calorimeter (DSC) Temperature is 165 ° C or higher   The thermoformed container according to claim 1, further comprising an ethylene-vinyl alcohol copolymer layer or an MXD6 polyamide resin layer as a barrier layer.   The thermoformed container according to claim 1 or 2, wherein the propylene-based resin composition contains an organic phosphate-based crystal nucleating agent.