JP5915592B2 - Thermoformed body, method for producing the same, and heat treatment method - Google Patents

Description

  The present invention relates to a thermoformed body, a manufacturing method thereof, and a heat treatment method, and more particularly to a thermoformed body that can withstand heat treatment, a manufacturing method thereof, and a heat treatment method.

  Conventionally, a molded body using a thermoplastic resin such as polystyrene, polyethylene terephthalate, or polypropylene has 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 is expanding to range-up containers in necessary microwave ovens, containers that require high-temperature filling, and the like.

  Such a molded body is manufactured by injection molding or thermoforming. Injection molding is suitable for the production of a molded body 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 molds are taken, the production speed is slower than thermoforming, 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 molded body. Thermoforming methods such as vacuum forming, vacuum pressure forming, and solid pressure forming are easy to mold and produce. It is widely used because it is suitable for mass production and it is easy to obtain a multilayered product.
However, thermoforming methods such as vacuum forming and vacuum / pressure forming, which form a molded product in a molten state, are reheated to a temperature above the melting point to form a container. However, productivity is inferior. Among thermoforming methods, solid-phase pressure molding can be molded at a temperature lower than the melting point of the resin, so the molding cooling time can be greatly shortened and the dimensional accuracy of the molded product is high. It is excellent in that a molded body can be produced at a high speed cycle (see Patent Document 1).

In recent years, packaging materials that can withstand high-temperature heat treatment have been demanded in order to ensure food safety, and various materials having heat resistance and sealing properties have been proposed for film materials (Patent Document 2). And Patent Document 3).
On the other hand, various materials have been proposed for thermoformed bodies from sheets (see Patent Documents 4 to 7), but it is not sufficient to obtain a molded body that can withstand high-temperature heat treatment by solid-state pressure forming. Usually, a molded body obtained by solid-phase pressure-molding a polypropylene resin has a large shrinkage ratio when subjected to high-temperature heat treatment. If solid-state pressure molding is performed at a temperature close to the melting point, the shrinkage rate decreases, but resin adhesion to the molding plug and perforation due to molding air tend to occur, the molding temperature range becomes very narrow, and productivity deteriorates. End up.
Therefore, there is a need for a thermoformed body that can be subjected to high-temperature heat treatment by solid-state pressure forming and a method for obtaining a formed body with high productivity.

JP 47-011489 A JP 2006-150892 A JP 2006-307120 A JP 2006-282259 A JP 2008-207818 A JP 07-126409 A JP 2011-126544 A

  An object of the present invention is to provide a thermoformed article that can be produced by solid-state pressure forming at a temperature below the melting peak temperature and has a low shrinkage rate by high-temperature heat treatment, in view of the above-mentioned problems of the prior art. There is.

As a result of intensive studies in order to solve the above problems, the present inventor used a polypropylene-based sheet composed of a specific propylene-based resin composition containing a specific amount of a β-crystal nucleating agent as a temperature below the melting peak temperature. It was found that solid pressure compression molding can be performed in a wide range of molding temperature conditions including, and the obtained thermoformed product has excellent heat resistance against high-temperature heat treatment, and the present invention has been completed.
The present invention provides the following thermoformed body, a method for producing the thermoformed body, and a heat treatment method.

[1] A thermoformed article that can contain contents to be subjected to heat treatment, containing 10 to 10,000 ppm of β-crystal nucleating agent (B), and MFR of 0.1 to 100 g / 10 min. A thermoformed article obtained by molding a resin sheet having a propylene-based resin layer made of a propylene-based resin (A) by a solid-state pressure forming method.
[2] The thermoformed article according to the above [1], wherein the β crystal fraction of the propylene-based resin layer is 3% or more and less than 20%.
[3] The thermoformed body according to the above [1] or [2], wherein the thermoformed body is a container having a deep drawing structure having a depth / caliber ratio of 0.5 or more.
[4] The thermoformed body according to any one of [1] to [3], wherein the resin sheet further includes a gas barrier layer.
[5] A method for producing a thermoformed article capable of storing the contents to be subjected to heat treatment, containing 10 to 10,000 ppm of β-crystal nucleating agent (B), and MFR of 0.1 to 100 g A method for producing a thermoformed article, characterized in that a resin sheet having a propylene-based resin layer made of a propylene-based resin (A) of / 10 min is formed by a solid-state pressure forming method.
[6] A heat treatment method in which the contents are stored in the thermoformed body according to any one of [1] to [4], and the contents are heat-treated.
[7] The heat treatment method according to the above [6], wherein the temperature of the heat treatment is 100 ° C. or higher.

The thermoformed article of the present invention can be widely applied to food containers, medical containers, and the like because the deformation of the container is very small even by high-temperature heat treatment.
In addition, by applying solid-state pressure forming methods such as plug-assist molding, container-shaped molded products with little deformation due to high-temperature heat treatment in a wide range of molding temperature conditions, despite differences in size and shape of the container, It is possible to stably and easily mold at a high speed cycle with good yield.

  The thermoformed article of the present invention is a thermoformed article that can contain the contents to be subjected to heat treatment, and contains 10 to 10,000 ppm of β-crystal nucleating agent (B), with an MFR of 0.1 to 0.1. A resin sheet having a propylene-based resin layer made of a propylene-based resin (A) of 100 g / 10 min is formed by a solid-state pressure forming method.

Hereinafter, the present invention will be described in order for each item. However, the present invention is not limited to the following description, and can be arbitrarily modified and implemented without departing from the technical scope of the present invention. .
In the present specification, when a numerical value is described before and after using the expression “to”, it is used in the meaning including the numerical values before and after that.

[Propylene resin (A)]
In this invention, specific propylene-type resin (A) is used as a 1st component used for the propylene-type resin layer which comprises the main layer of the resin sheet which performs thermoforming.
The propylene-based resin (A) used in the present invention is characterized in that the melt flow rate (MFR) measured at a temperature of 230 ° C. and a load of 2.16 kg is 0.1 to 100 g / 10 minutes.
When the MFR is less than 0.1 g / 10 min, the melt fluidity is lowered and sheet forming becomes difficult. On the other hand, if the MFR exceeds 100 g / 10 min, sheet forming becomes difficult due to drawdown, which is not preferable. Among these, MFR is preferably 0.4 to 20 g / 10 minutes, and more preferably 0.4 to 5 g / 10 minutes.

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”. : Value measured at 230 ° C. and 2.16 kg load.
The melt flow rate (MFR) of the propylene-based resin (A) can be controlled by a conventionally known method. Usually, the temperature and pressure, which are polymerization conditions of the propylene-based resin, are adjusted or added during polymerization. This can be achieved by controlling the amount of chain transfer agent such as hydrogen added.

  The melting point of the propylene-based resin (A) before containing the β crystal nucleating agent is preferably 155 to 170 ° C, and more preferably 160 to 170 ° C.

-Manufacturing method of propylene-type resin (A) As a polymerization catalyst for manufacturing propylene-type resin (A) used by this invention, a Ziegler Natta type | mold catalyst, a metallocene catalyst, etc. are mentioned.
As a polymerization method of the propylene-based resin (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 performed not only in a single reactor but also in multiple stages using a plurality of reactors, and a plurality of polymerization methods may be used in combination, for example, a bulk method-gas phase method.

  In the present specification, when the term propylene-based resin (A) is used, it is a copolymer of propylene and an α-olefin other than propylene as long as it satisfies the requirements of the MFR. It may be. However, among all α-olefin components including propylene, it means the one having the largest mol% of propylene. In the present specification, unless otherwise specified, the term “α-olefin” excludes propylene and includes ethylene. Therefore, the propylene-based resin (A) includes a homopolymer of propylene, a random copolymer of propylene and an α-olefin, and the like, and can be used as one type or as a mixture of two or more types.

Examples of the α-olefin used in the propylene copolymer such as a random copolymer of propylene and α-olefin include α-olefins having 2 to 20 carbon atoms. Preferably α-olefin having 2 to 8 carbon atoms such as ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, more preferably carbon such as ethylene, 1-butene, etc. These are α-olefins of 2 to 4, and these α-olefins may be one kind of copolymer or two or more kinds of multi-component copolymers.
Specifically, propylene-ethylene copolymer, propylene-1-butene copolymer, propylene-ethylene-1-butene copolymer, propylene-ethylene-1-pentene copolymer, propylene-1-pentene copolymer Examples thereof include various binary or ternary copolymers such as a copolymer, a propylene-1-hexene copolymer, a propylene-4-methyl-1-pentene copolymer, and a propylene-1-octene copolymer.

  Moreover, the catalyst used for the polymerization is preferably 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 rate or a constant pressure in the reaction tank, 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. Further, the amount of prepolymerization is such that the amount of prepolymerized polymer is a weight ratio with respect to the catalyst component 1, and is preferably 0.01 to 100, more preferably 0.1 to 50. Moreover, a catalyst component can also be added or added at the time of 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.

-Polymerization catalyst and polymerization method Any polymerization method can be adopted as long as the olefin polymerization catalyst and the monomer come into efficient contact.
Specifically, a slurry method using an inert solvent, a so-called bulk method using a propylene as a solvent without using an inert solvent as a solvent, a solution polymerization method, or a monomer without using a liquid solvent substantially. A gas phase method can be used. Moreover, the method of performing continuous polymerization and batch type polymerization is also applied. In addition to single-stage polymerization using only one reactor, it is possible to perform 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 polymerization solvent.
The polymerization temperature, polymerization pressure, and molecular weight regulator are preferably set as follows. The polymerization temperature is usually 0 ° C. or higher and 150 ° C. or lower. In particular, when bulk polymerization is used, the temperature is preferably 40 ° C or higher, more preferably 50 ° C or higher. 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 as a relative pressure to the atmosphere. 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, the relative pressure to the atmosphere is preferably 1.5 MPa or more, more preferably 2.0 MPa or more. 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.

Moreover, you may perform the copolymerization which uses a C2-C20 alpha olefin as a comonomer besides propylene. When the propylene resin (A) is copolymerized with an α-olefin other than propylene, the (total) comonomer content in the propylene resin (A) is preferably 0.1 mol% or more and 1 mol. It is also possible to use a plurality of the above-mentioned comonomers. Specific examples of preferable comonomers include α-olefins having 2 to 8 carbon atoms such as ethylene, 1-butene, 1-hexene, 1-octene and 4-methyl-1-pentene (excluding propylene). More preferable are α-olefins having 2 to 4 carbon atoms such as ethylene and 1-butene (excluding propylene).
Specific examples of the propylene-based resin (A) include “NOVATEC (registered trademark) PP” manufactured by Nippon Polypro Co., Ltd.

[Β crystal nucleating agent (B)]
In the present invention, the β crystal nucleating agent (B) is used for the propylene-based resin (A) constituting the material sheet to be subjected to solid-state pressure forming. By containing the β crystal nucleating agent (B) in the polypropylene-based resin (A), the shrinkage rate when the thermoformed body (such as a container) obtained by solid-phase pressure molding is heat-treated can be reduced. The thermoformed body (such as a container) of the present invention can heat the contained contents at 100 ° C. or higher, and further can be processed at 110 ° C. or higher, particularly 120 ° C. or higher. The shrinkage rate at that time is remarkably reduced.

  The β-crystal nucleating agent (B) is not particularly limited as long as it is a crystallization nucleating agent that selectively forms β-crystals by adding it to a polypropylene resin, but various pigment-based compounds (such as quinacridone) and amides. System compounds can be preferably used.

As the β crystal nucleating agent (B), an amide compound represented by the following general formula is particularly preferable. By using an amide compound represented by the following general formula, it becomes easy to achieve high β crystal forming ability.
R ² —NHCO—R ¹ —CONH—R ³
In the formula, R ¹ represents an aromatic ring, an alicyclic ring or an aliphatic hydrocarbon having 2 to 24 carbon atoms, and R ² and R ³ represent an alicyclic ring or an aromatic ring. Preferably, R ¹ is an alicyclic hydrocarbon, and specific examples include cyclohexane, cycloheptane, and cyclooctane. R ² and R ³ are preferably aromatic rings, and specific examples include a benzene ring, a naphthalene ring, and an anthracene ring.

  Preferred specific examples of the amide compound represented by the above general formula include N, N′-diphenylhexanediamide, N, N′-dicyclohexylterephthalamide, N, N′-dicyclohexyl-2,6-naphthalenedicarboxamide. In particular, N, N′-dicyclohexyl-2,6-naphthalenedicarboxamide is preferable.

The content of the β crystal nucleating agent (B) is 10 to 10,000 ppm (weight ppm), preferably 100 ppm to 3,000 ppm, and more preferably 500 ppm to 1,000 ppm.
If it is less than 10 ppm, sufficient β-crystal forming activity cannot be ensured, and even if it contains more than 10,000 ppm, the effect of the β-crystal nucleating agent is not substantially changed and it is economically disadvantageous. Is not preferable because of concern.
The β crystal nucleating agent can be used alone or in combination of two or more.

  The mixing of these propylene-based resin (A), β crystal nucleating agent (B), and other compounding agents described below, for example, a mixer with a high-speed stirrer such as a gelation mixer, a Henschel mixer or a super mixer, a ribbon Ordinary mixing devices such as blenders and tumblers can be used, and extruders, kneaders, calendar rolls and the like can also be used. Propylene-based resin materials can be obtained by kneading these devices while being melt-dispersed in a single machine or a mixer used in combination with two machines and then pelletizing them.

[Other ingredients]
A compounding agent other than the polypropylene resin (A) and the β crystal nucleating agent (B) can be used for the polypropylene resin (A) as long as the effects of the present invention are not significantly impaired.
In the propylene resin (A) used in the present invention, a polymer other than the polypropylene resin (A) can be blended.
Other polymers include propylene alone or copolymers of propylene and other α-olefins (excluding those corresponding to propylene resin (A)), low density polyethylene, heavy polyethylene such as high density polyethylene, etc. Examples include coalescence and various thermoplastic elastomers.
Specifically, the propylene-based resin composition (A) is preferably 80% by weight or more, and the remaining preferably 0 to 20% by weight is composed of various general-purpose propylene (co) polymers, ethylene-propylene copolymers ( However, except those corresponding to the propylene-based resin (A).), Low density or high density polyethylene, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylate copolymer, resins such as various elastomers, Materials such as elastomers, fillers and additives can be arbitrarily blended. These compounding materials are provided with characteristics that serve as a propylene-based resin layer that is a main layer.

In addition, for the propylene-based resin (A), an antioxidant, a neutralizing agent, a light stabilizer, an ultraviolet absorber, an antiblocking agent, a lubricant, an antistatic agent, a metal deactivator, and the like can be usually used for polypropylene. Various additives can be blended as long as the object of the present invention is not impaired.
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.

[Resin sheet]
The resin sheet used for the thermoformed article of the present invention is a sheet comprising a main layer using a propylene-based resin (A) containing at least one β-crystal nucleating agent (B), and is a multilayer having two or more layers. It doesn't matter what the structure is. For example, between the main layer and the innermost layer, an ethylene-vinyl alcohol copolymer, a metaxylylene adipamide-based polyamide resin (MXD6 polyamide) obtained using metaxylylenediamine and adipic acid as main components, and the like It is also preferable to provide a barrier layer having a barrier property (barrier resin layer) and an adhesive layer.
It is also possible to arrange a layer having a design property such as a high gloss layer or a low gloss layer as the outermost layer.

In particular, in medical containers and food containers that are subjected to heat treatment, in order to prevent oxidative deterioration of the contents, it is preferable to have a multilayer structure using a barrier resin as a barrier layer. For this reason, the resin sheet of the present invention comprises a main layer constituting a thermoformed body (container) main body portion, an ethylene-vinyl alcohol copolymer (EVOH), metaxylylene adipamide (MXD6 polyamide), conjugated diene heavy Various materials consisting of a mixture of a cyclized product and an ethylene-vinyl alcohol copolymer, polyvinyl alcohol, polyvinylidene chloride (PVDC), maleic anhydride modified polypropylene, high impact polystyrene (HIPS), amorphous polyethylene terephthalate, low expanded polystyrene, etc. It is also possible to make a laminate having a so-called three-layer structure or four-layer structure in consideration of gas barrier properties.
Among the above, the gas barrier layer is preferably an ethylene-vinyl alcohol copolymer (EVOH), a metaxylylene adipamide-based polyamide resin, a mixture of a conjugated diene polymer cyclized product and an ethylene-vinyl alcohol copolymer. .

  The thickness of the resin 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. When thickness is less than 0.3 mm, there exists a possibility that the rigidity of the molded object obtained may be impaired. On the other hand, if the thickness exceeds 4 mm, sheet molding may be difficult.

Further, when the resin sheet has a barrier layer, the thickness ratio of the barrier layer to the main layer (barrier layer / main layer) is preferably 0.02 or more and 2 or less, more preferably 0.04 or more and 0.15 or less. Preferably, it is 0.06 or more and 0.12 or less. If the thickness ratio between the barrier layer and the main layer is less than 0.02, the barrier resin may absorb water during heat treatment (for example, retort treatment), and the barrier performance may be deteriorated. If the thickness ratio exceeds 2, the barrier layer may be unevenly stretched during molding of the container, which may reduce the commercial value of the container.
In addition, when a resin sheet consists of a main layer and a barrier layer in this invention, there may exist other layers in the range which does not impair the effect of this invention on the outer side of a barrier layer and / or a main layer. Similarly, there may be other layers between the main layer and the barrier layer.

In order to obtain such a resin sheet, it is possible to form a resin sheet having a plurality of layers using a feed block or a multi-manifold using an extruder having a plurality of dies usually used for forming polypropylene.
As an example of a specific method for producing a resin sheet, a propylene-based resin (A) and a β crystal nucleating agent (B) are passed through a known single-screw or twin-screw extruder to form a sheet from a coat hanger die. After being extruded, the metal roll surface (in which cooling water or oil circulates) is pressed and solidified by cooling with an air knife, air chamber, hard rubber roll, steel belt, or metal roll. . 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 smoothness can be obtained. .

[Thermoforming body]
The thermoformed body of the present invention is obtained by solid-phase pressure forming using a polypropylene sheet.
The thermoformed article of the present invention is preferably obtained by plug-assisted solid-phase pressure forming and has excellent container rigidity and impact strength. Usually, in the solid-state pressure forming, it is difficult to obtain a formed body with small shrinkage due to heat treatment. However, the thermoformed body (such as a container) of the present invention becomes a formed body with small shrinkage due to heat treatment. On the other hand, the thermoformed body (container or the like) of the present invention can contain the contents, and the shrinkage rate when this is heat-treated at a high temperature by heat treatment or retort treatment can be remarkably reduced.

The thermoformed article of the present invention uses the above resin sheet, and is preferably formed by softening the sheet at a temperature not higher than the melting peak temperature of the main layer, and is preferably obtained by a plug-assisted solid-state air pressure molding machine. .
Examples of the heating method in such molding include indirect heating, hot plate heating, and hot roll heating. If the molding is performed at a temperature exceeding the melting peak temperature of the sheet, the transparency, gloss, and thickness uniformity of the resulting thermoformed body (container) are likely to deteriorate, adhere to the assist plug, and use compressed air. This is not preferable because perforation may occur or molding may become impossible.
The thermoformed article of the present invention plugs such solid-phase pressure molding at a temperature lower than the melting peak temperature of the propylene-based resin (A) containing the β-crystal nucleating agent (B) of the main layer constituting the resin sheet. It is preferable to carry out and manufacture by assist molding.

  When the plug-assisted solid-phase pressure molding, which is a preferable molding method, is performed at a temperature below the melting peak temperature of the main layer of the propylene-based resin composition (A), the melting peak temperature range is preferably in the range of 5 to 30 ° C. The main layer is softened by heating at a temperature, and then the assist plug is pushed down to make a polypropylene sheet into a container shape, and pre-shaped into a container shape by solid-state pressure molding, A thermoformed article can be molded by applying air pressure to the shaped portion to bring the resin sheet into close contact with the mold cavity surface.

[Β crystal fraction of thermoformed body]
In the thermoformed article of the present invention, the β crystal fraction of the propylene-based resin layer is preferably 3% or more and less than 20%. If it is less than 3%, shrinkage due to heat treatment tends to be large, and if it is 20% or more, it can be obtained at the time of molding at a melting point or higher, but it is melt molding, and it is difficult to manufacture in solid-state pressure molding. The β crystal fraction is preferably 3% or more and less than 15%.
Note that the β crystal fraction is obtained by cutting out a test piece from the center portion in the height direction of the side surface of the thermoformed body, and measuring the cut out test piece by X-ray diffraction. The specific method is as described in Examples below.

[Deep drawing thermoformed body]
The thermoformed article of the present invention is obtained by solid-state pressure forming using the resin sheet, and the molded article is a container-shaped heat having a deep drawing structure having a depth / caliber ratio of 0.5 or more. A molded container is preferred.
The thermoformed container has a squeezing ratio of 0. which is the ratio of the (maximum) depth to the bottom of the container body and the (maximum) width (bore) of the container body, regardless of whether the container shape is square or round. It is preferably 5 or more, and more preferably 1.0 or more. The deep drawing ratio can be measured with calipers or the like as exemplified in the examples of the present specification.
Those having a drawing ratio of 0.5 or more are preferably obtained by plug-assisted solid-state pressure forming, and are excellent in the rigidity and impact strength of the container. A container with small shrinkage due to heat treatment is difficult to obtain. However, the thermoformed article of the present invention can be a deep-drawn container with small shrinkage due to heat treatment even if the drawing ratio is 1.0 or more.

[Use of thermoformed container]
The thermoformed article of the present invention has excellent design properties and can be subjected to retort heat treatment, and therefore can be used for containers in various fields such as food containers, detergent containers, and medical containers. Can be used.
In particular, since the thermoformed article of the present invention is excellent in heat resistance against heat treatment at high temperatures, the contents can be stored in the thermoformed article and subjected to heat treatment and retort treatment at a high temperature. Become. The heat treatment temperature at this time can be 100 ° C. or higher, further 110 ° C. or higher, and further can be processed at 120 ° C. or higher.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. The values of various production conditions and evaluation results in the following examples have meanings as preferred values of the upper limit or lower limit in the embodiment of the present invention, and preferred ranges are the upper limit or lower limit values described above, and It may be a range defined by a combination of values of the examples or values between the examples.
In Examples and Comparative Examples, various physical properties of the 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 method]
(1) Melt flow rate (MFR) [unit: g / 10 min]:
The MFR of the propylene-based resin (A) is JIS K7210: 1999 “Method of 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 (melting point, Tm):
Using a differential scanning calorimeter (DSC) “Q2000” manufactured by TA Instruments, 5 mg aluminum pan is filled with a sample (propylene resin, its composition or sheet), and the temperature rising rate from room temperature to 200 ° C. is 100 ° C. / The temperature is raised for 5 minutes, held for 5 minutes, and then lowered to 40 ° C. at 10 ° C./minute to obtain the crystallization temperature (Tc) as the maximum crystal peak temperature (° C.) when crystallization is performed. The melting peak temperature (Tm) was determined as the main maximum melting peak temperature (° C.) of 100 ° C. or more and 155 ° C. or less when the temperature was raised to 200 ° C. at a rate of ° C./min.

(3) Drawing ratio of thermoformed body:
The mouth outer diameter and depth of the obtained thermoformed container were measured with calipers, and the ratio (depth / outer diameter) was taken as the drawing ratio.

(4) β crystal fraction of the propylene-based resin layer:
The β crystal fraction of the propylene-based resin layer is determined according to Turner Jones et al., “Makromol. Chem. Chem. Chem. Chem. Chem. 75, 135-137 (1964) "and calculated using the following formula. For X-ray diffraction, the center part in the height direction of the thermoformed container was cut out, and the circumferential direction of the container was measured by a transmission method. Measurement is X-ray manufactured by Rigaku.
Using a diffractometer SmartLab, measurement was performed at a wavelength of 1.54 mm, an output of 40 KV and 30 mA, a 2θ scan range of 5 to 40 ° in 0.1 ° steps and a scan speed of 10 ° / min.
β crystal fraction = (hβ) / (hβ + hα ₁ + hα ₂ + hα ₃ ) × 100
Where hβ is the diffraction intensity (height) of the β crystal (300) plane, hα ₁ is the diffraction intensity (height) of the α crystal (110) plane, and hα ₂ is the diffraction intensity (height) of the α crystal (040) plane. Hα ₃ represents the diffraction intensity (height) by the α crystal (130) plane.

(5) Resin temperature during solid-phase pressure molding:
The sheet surface temperature immediately before forming in the solid-state pressure forming machine was measured with a non-contact type radiation thermometer, and the maximum temperature (MAX) and the minimum temperature (MIN) were confirmed.
(6) Formability (plug adhesion):
Using the obtained resin sheet, container molding was performed at a speed of 12 shot / min for 30 minutes continuously, and it was confirmed whether the resin sheet adhered to the plug.
○: No resin sheet adhered ×: Resin sheet adhered and cannot be molded

(7) Heat resistance resistance:
The obtained thermoformed container was treated in an oven at a temperature of 125 ° C. for 30 minutes, the volume before and after the measurement was measured, and the volume shrinkage (%) was measured. The smaller the volume shrinkage rate, the better the heat resistance, and it was judged as “Good” according to the following criteria.
○: Less than 3% ×: 3% or more

(8) Molding temperature condition range For those with heat resistance of “◯”, the heater temperature setting range at the time of molding was examined as the molding temperature condition width. It is evaluated that the larger the temperature range is, the more excellent it is, and specifically, the one having a temperature condition width of 5 ° C. or more is good.

[2. Materials used]
(1) Propylene resin (A):
The following propylene resins were used as the propylene resin (A).
“EA9H” (trade name, manufactured by Nippon Polypro Co., Ltd., propylene homopolymer)
MFR = 0.5 g / 10 min “FY6H” (trade name, manufactured by Nippon Polypro Co., Ltd., propylene homopolymer)
MFR = 1.9 g / 10 min “FY4” (trade name, manufactured by Nippon Polypro Co., Ltd., propylene homopolymer)
MFR = 5.0 g / 10 min (2) β crystal nucleating agent (B)
The following was used as the β crystal nucleating agent (B).
N, N′-dicyclohexyl-2,6-naphthalenedicarboxamide New Nippon Rika Co., Ltd., trade name “NJESTER NU-100”

Example 1
The mixture consisting of NU-100: 0.1% by weight and EA9H: 99.9% by weight was extruded at a temperature of 230 ° C. with a single screw extruder having a diameter of 50 mmφ to obtain propylene-based resin pellets.
This propylene resin pellet is put into an extruder with a screw diameter of 50 mm, and a polypropylene sheet obtained by heat melting and plasticizing at a resin temperature of 230 ° C. and extruding from a T-type die is mirror-finished with a surface temperature controlled to 80 ° C. The resin sheet having a width of 500 mm and an overall thickness of 2.0 mm was obtained by continuously taking it out at a speed of 1 m / min while being cooled and solidified.
Next, using this resin 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 container molding temperature was 146.1 ° C.
The thermoformed body was subjected to the various evaluations described above. The results are shown in Table 1.

(Example 2)
The same operation as in Example 1 was performed except that FY6H was used instead of EA9H.
The results are shown in Table 1.
(Example 3)
The same procedure as in Example 1 was carried out except that FY6H was used instead of EA9H, and a mixture consisting of NU100: 0.02 wt% and FY6H: 99.98 wt% was used.
Example 4
The same procedure as in Example 1 was carried out except that FY6H was used instead of EA9H, and a mixture consisting of NU100: 0.05 wt% and FY6H: 99.95 wt% was used.
(Example 5)
The same procedure as in Example 1 was carried out except that FY6H was used instead of EA9H, and a mixture consisting of NU100: 0.2 wt% and FY6H: 99.8 wt% was used.
(Example 6)
It implemented like Example 1 except having used FY4 instead of EA9H.
The results are shown in Table 1.

(Example 7)
The mixture comprising NU-100: 0.1 wt% and FY6H: 99.9 wt% was extruded at a temperature of 230 ° C. with a single screw extruder having a diameter of 50 mmφ to obtain propylene-based resin pellets.
This resin pellet is introduced into an extruder with a screw diameter of 50 mm, and EVOH pellets (“BX6804B”, trade name, manufactured by Nippon Synthetic Chemical Industry) are introduced into an extruder with a screw diameter of 40 mm, and another screw diameter of 40 mm. An adhesive resin (“Modic P604V”, trade name, manufactured by Mitsubishi Chemical Co., Ltd., adhesive polypropylene resin) was put into an extruder of No. 1, and melted and plasticized at a resin temperature of 230 ° C. and extruded from a T-die. A polypropylene sheet is sandwiched by a mirror-finished metal cast roll whose surface temperature is controlled at 80 ° C., and continuously cooled and solidified at a speed of 1 m / min, width 500 mm, EVOH layer thickness 0.1 mm. A three-kind five-layer sheet having an adhesive resin thickness of 0.1 mm and an overall thickness of 2.0 mm was obtained.
Next, a thermoformed container having a diameter of 75 mmφ and a depth of 105 mm was formed using the laminated resin sheet with 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 8)
It implemented like Example 7 except having used metaxylylylene adipamide resin (brand name "MXD6 S7007", Mitsubishi Gas Chemical Co., Ltd. product) instead of EVOH.
The evaluation results are shown in Table 1.
Example 9
It implemented similarly to Example 7 except having used the mixture (brand name "Quintia", Nippon Zeon Co., Ltd. product) of the conjugated diene polymer cyclization thing and the ethylene-vinyl alcohol copolymer instead of EVOH.
The evaluation results are shown in Table 1.

(Comparative Example 1)
The same operation as in Example 2 was conducted except that the β crystal nucleating agent was not used.
The evaluation results are shown in Table 2.
(Comparative Example 2)
The same operation as in Example 6 was performed except that the β crystal nucleating agent was not used.
The evaluation results are shown in Table 2.
(Comparative Example 3)
The same operation as in Example 1 was carried out except that no β crystal nucleating agent was used.
The evaluation results are shown in Table 2.

  As is clear from Table 1 and Table 2 above, in the examples satisfying the provisions of the present invention, a thermoformed body with small shrinkage by heat treatment assuming heat treatment in solid-state pressure forming was stably obtained. On the other hand, the thermoformed article obtained in the comparative example not satisfying the provisions of the present invention was a thermoformed article having a poor commercial value due to large shrinkage caused by heat treatment assuming heat treatment.

  The thermoformed article of the present invention is a container that can be heat-treated with excellent design by solid-phase pressure forming, and therefore can be widely used in the fields of food containers and beverage containers, and has industrial applicability. Is very big.

Claims (6)

A method for producing a thermoformed article capable of storing contents to be subjected to heat treatment, comprising 10 to 10,000 ppm of β-crystal nucleating agent (B), MFR (230 ° C., 2.16 kg load) A method for producing a thermoformed article, comprising molding a resin sheet having a propylene-based resin layer made of a propylene-based resin (A) of 0.1 to 100 g / 10 min by a solid-state pressure forming method. The method for producing a thermoformed article according to claim 1, wherein the propylene-based resin layer has a β crystal fraction of 3% or more and less than 20%. The method for producing a thermoformed article according to claim 1 or 2, wherein the thermoformed article is a container having a deep drawing structure having a depth / caliber ratio of 0.5 or more. The said resin sheet is a manufacturing method of the thermoforming body in any one of Claims 1-3 which further has a gas barrier layer. The heat processing method which stores a content in the thermoforming body manufactured by the manufacturing method of the thermoforming body in any one of Claims 1-4, and heat-processes a content. The heat treatment method according to claim 5 , wherein the temperature of the heat treatment is 100 ° C. or higher.