JP5915593B2 - 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. Because of its high performance, it is widely used because it is suitable for mass production and it is easy to obtain multilayered products.
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 having a small shrinkage rate when a polypropylene sheet can be produced by solid-state pressure forming at a temperature lower than the melting peak temperature in view of the problems of the prior art. It is to provide.

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] Propylene which can store contents to be subjected to heat treatment, contains 10 to 10,000 ppm of β crystal nucleating agent (B), and satisfies the following (1) and (2) A thermoformed article obtained by molding a resin sheet having a propylene-based resin layer made of a resin-based resin composition (A) by a solid-state pressure forming method.
(1) MFR is 0.1 to 100 g / 10 min.
(2) 60 to 99 parts by weight of propylene polymer component (A1) and 40 to 1 part by weight of ethylene-α-olefin copolymer component (A2) containing 30 to 99.9% by weight of ethylene (provided that ( (The sum of components A1) and (A2) is 100 parts by weight.)
[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 containing the contents to be subjected to heat treatment, comprising 10 to 10,000 ppm of the β crystal nucleating agent (B), and the following (1) and (2 A resin sheet having a propylene-based resin layer made of the propylene-based resin composition (A) satisfying (2) is molded by a solid-state pressure forming method.
(1) MFR is 0.1 to 100 g / 10 min.
(2) 60 to 99 parts by weight of the propylene polymer component (A1) and 40 to 1 part by weight of the ethylene-α-olefin copolymer component (A2) containing 30 to 99.9% by weight of ethylene (provided that (The sum of components (A1) and (A2) is 100 parts by weight.)
[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 the β crystal nucleating agent (B), and the following (1) and ( A resin sheet having a propylene-based resin layer made of the propylene-based resin composition (A) satisfying 2) is formed by a solid-state pressure forming method.
(1) MFR is 0.1 to 100 g / 10 min.
(2) 60 to 99 parts by weight of the propylene polymer component (A1) and 40 to 1 part by weight of the ethylene-α-olefin copolymer component (A2) containing 30 to 99.9% by weight of ethylene (provided that (The sum of components (A1) and (A2) is 100 parts by weight.)

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-based resin composition (A)]
In the present invention, a specific propylene resin composition (A) is used as the first component used in the propylene resin layer constituting the main layer of the resin sheet to be thermoformed.
The propylene-based resin composition (A) used in the present invention has a melt flow rate (MFR) measured at a temperature of 230 ° C. and a load of 2.16 kg of 0.1 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.

  In the present invention, the melt flow rate (MFR) of the propylene-based polymer is JIS K6921-2, “Plastic-polypropylene (PP) molding and extrusion material—Part 2: How to make test specimens and properties This is a value measured under test conditions: 230 ° C. and 2.16 kg load according to “How to obtain”.

  The propylene-based resin composition (A) contains 60 to 99 parts by weight of the propylene polymer component (A1) and 30 to 99.9% by weight of ethylene with respect to a total of 100 parts by weight of the components (A1) and (A2). The ethylene-α-olefin copolymer component (A2) to be contained is contained in an amount of 40 to 1 part by weight.

The melting point of the propylene-based resin composition (A) is preferably 155 to 170 ° C, and more preferably 160 to 170 ° C.

・ Propylene polymer component (A1)
The propylene polymer component (A1) is a propylene polymer, preferably a crystalline propylene polymer, and preferably has an isotactic index (I.I.) of 90% or more, particularly 95% or more. It is.
The MFR of the propylene polymer component (A1) is preferably 0.5 to 200 g / 10 minutes, more preferably 0.5 to 50 g / 10 minutes, and particularly preferably 0.5 to 20 g / 10 minutes. . The propylene polymer component (A1) may be used alone or as a mixture of plural kinds of polymers.

In the present specification, when the term propylene polymer component (A1) is used, even if it satisfies the above requirements, a propylene homopolymer is a co-monomer composed of propylene and an α-olefin other than propylene. It may be a polymer. However, among all α-olefin components including propylene, it means the one having the largest mol% of propylene. Therefore, the propylene polymer component (A1) includes a homopolymer of propylene, a random copolymer of propylene and α-olefin, and the like, and can be used as one kind or as a mixture of two or more kinds.
The (total) α-olefin content in the propylene polymer component (A1) is preferably 1.0% by weight or less.

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 4 to 20 carbon atoms. Preferred are α-olefins having 2 to 4 carbon atoms such as ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, etc., more preferably ethylene, 1-butene, etc. These α-olefins having 2 or 4 carbon atoms may be used as one type of copolymer or as two or more types 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.

The propylene polymer component (A1) may be produced with a Ziegler catalyst or a metallocene catalyst, but a propylene polymer obtained with a Ziegler catalyst is preferred because of its excellent moldability.
As the Ziegler catalyst, a highly stereoregular catalyst is usually used. For example, a catalyst comprising a combination of a titanium trichloride composition obtained by reducing titanium tetrachloride with an organoaluminum compound and further treating with various electron donors and electron acceptors, an organoaluminum compound and an aromatic carboxylic acid ester, Examples thereof include supported catalysts in which titanium tetrachloride and various electron donors are brought into contact with magnesium halide.

  As the polymerization method, 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.

・ Ethylene-α-olefin copolymer component (A2)
The ethylene-α-olefin copolymer component (A2) is a random copolymer of ethylene and α-olefin, and the copolymerization ratio of ethylene is 30 to 99.9% by weight. The copolymerization ratio of ethylene is preferably 35 to 99.9% by weight, more preferably 50 to 99.9% by weight, and still more preferably 50 to 85% by weight.
The α-olefin of the ethylene-α-olefin copolymer component (A2) is preferably an α-olefin having 3 to 20 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 1-octene. And α-olefins such as 3-methyl-1-butene and 4-methyl 1-pentene, and vinyl compounds such as styrene, vinylcyclopentene, vinylcyclohexane and vinylnorbornane. Of these, propylene, 1-butene, 1-hexene and 1-octene are preferable as the α-olefin, and propylene, 1-butene and 1-hexene are particularly preferable.
Two or more α-olefins may be copolymerized.

The MFR (measured at 230 ° C., 2.16 kg load) of the ethylene-α-olefin copolymer component (A2) is preferably 1 / 1000,000 to 20 g / 10 minutes, more preferably 1/1. 1,000,000 to 15 g / 10 min, more preferably 1 / 1,000,000 to 10 g / 10 min, particularly 1 / 10,000 to 10 g / 10 min, most preferably 1/100 to 10 g / min. 10 minutes is preferred.
In addition, when manufacturing a component (A1) and a component (A2) by sequential polymerization mentioned later, MFR of an ethylene-alpha-olefin copolymer component (A2) is calculated | required by the relationship of following Formula.
Log (total MFR) = (ratio of component (A2)) × Log (MFR of component (A2)) + (ratio of 1-component (A2)) × Log (MFR of component (A1))

The ethylene-α-olefin copolymer component (A2) may be produced with a Ziegler catalyst or with a metallocene catalyst, but the product obtained with a Ziegler catalyst has a wide molecular weight distribution, so that the moldability is improved. Since it is excellent, it is preferable.
As the Ziegler catalyst, a highly stereoregular catalyst is usually used. For example, a catalyst comprising a combination of a titanium trichloride composition obtained by reducing titanium tetrachloride with an organoaluminum compound and further treating with various electron donors and electron acceptors, an organoaluminum compound and an aromatic carboxylic acid ester, Examples thereof include supported catalysts in which titanium tetrachloride and various electron donors are brought into contact with magnesium halide.

  As the polymerization method, 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.

[Production of Propylene Resin Composition (A)]
As described above, the propylene-based resin composition (A) has 60 to 99 parts by weight of the propylene polymer component (A1) and 100% by weight of the ethylene-α-olefin copolymer, with respect to the total of 100 parts by weight of the components (A1) and (A2). 40 to 1 part by weight of the polymer component (A2) is contained. The preferred contents of the components (A1) and (A2) are 50 to 95 parts by weight of the propylene polymer component (A1) and 50 to 5 parts by weight of the ethylene-α-olefin copolymer component (A2).

The propylene-based resin composition (A) is also produced by separately producing two polymer components, a propylene polymer component (A1) and a propylene-ethylene copolymer component (A2), and then blending them. I can do it.
Further, from the viewpoint of neatly dispersing the ethylene-α-olefin copolymer component (A2) in the propylene polymer component (A1), both the components are subjected to multistage polymerization (hereinafter sometimes referred to as “sequential polymerization”). It is also desirable to manufacture.

-Sequential polymerization In the case of sequential polymerization, specifically, after the polymerization of the propylene polymer component (A1) in the first step, the polymerization of the ethylene-α-olefin copolymer component (A2) in the second step. Is desirable.
Moreover, when performing sequential polymerization, either a batch method or a continuous method can be used, but it is generally desirable to use a continuous method from the viewpoint of productivity.
In the case of the batch method, the propylene polymer component (A1) and the ethylene-α-olefin copolymer component (A2) are individually polymerized using a single polymerization reactor by changing the polymerization conditions with time. It is possible. A plurality of polymerization reactors may be connected in parallel.
In the case of a continuous process, it is necessary to use a production facility in which two or more polymerization reactors are connected in series because the propylene polymer component (A1) and the ethylene-α-olefin copolymer component (A2) need to be individually polymerized. There is.

-Polymerization process Any polymerization process can be used.
The reaction phase may be a method using a liquid medium or a method using a gas medium. Specific examples include a slurry method, a bulk method, and a gas phase method.

-General polymerization conditions The polymerization temperature can be used without any particular problem as long as it is within the usual temperature range. Specifically, a range of 0 ° C to 200 ° C, preferably 40 ° C to 100 ° C can be used.
The polymerization pressure varies depending on the process to be selected, but can be used without any problem as long as it is in a pressure range usually used. Specifically, a range of greater than 0 to 200 MPa, preferably 0.1 to 50 MPa can be used. At this time, there is no problem even if an inert gas such as nitrogen coexists.
Moreover, in the 2nd process which manufactures an ethylene-alpha-olefin copolymer component (A2), polymerization inhibitors, such as ethanol and oxygen, can also be added.

The propylene polymer component (A1) obtained by the above-described multistage polymerization (sequential polymerization) and the ethylene-α-olefin copolymer component (A2) in which the α-olefin is propylene are known in the art as “propylene -“Ethylene block copolymer”, which is a blended state of component (A1) and component (A2), both of which are bonded by polymerization to form a real block structure. Any of them may correspond to the propylene-based resin composition (A) in the present invention.
Moreover, it is also preferable to mix | blend a propylene polymer component (A1) and / or an ethylene-alpha-olefin copolymer component (A2) with such a propylene-ethylene block copolymer.

[Β crystal nucleating agent (B)]
In the present invention, a β crystal nucleating agent (B) is contained in the propylene-based resin constituting the material sheet to be subjected to solid-state pressure forming. By containing the β crystal nucleating agent (B), it is possible to reduce the shrinkage rate when the thermoformed body (container or the like) obtained by solid phase pressure forming is heat-treated. 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 the components (A1) and (A2) with the β crystal nucleating agent (B) and the other compounding agents described below is, for example, mixing with a high-speed stirrer such as a gelation mixer, a Henschel mixer, or a super mixer. Usual mixing devices such as a machine, ribbon blender, and tumbler can be used, and an extruder, kneader, calendar roll, etc. 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]
In the propylene-based resin layer composed of the above, a compounding agent other than the above can be used as long as the effect of the present invention is not significantly impaired.
In the propylene-based resin composition (A), a polymer other than the component (A1) and the component (A2) can be blended. Other polymers include various propylene (co) polymers (excluding those corresponding to component (A1) and component (A2)), polymers such as low density polyethylene and high density polyethylene, various thermoplastic elastomers, etc. Can be mentioned.
Specifically, the component (A1) and the component (A2) are preferably 80% by weight or more, preferably the remaining 0 to 20% by weight are general-purpose various propylene (co) polymers and ethylene-propylene copolymers. (Excluding those corresponding to component (A2)), resins such as low density or high density polyethylene, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylate copolymer, various elastomers, and elastomers In addition, materials such as 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 composition (A), an antioxidant, a neutralizing agent, a light stabilizer, an ultraviolet absorber, an anti-blocking agent, a lubricant, an antistatic agent, a metal deactivator, etc. are usually used for polypropylene. Various additives that can be used 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.

[Resin sheet]
The resin sheet used in the thermoformed article of the present invention is a sheet comprising a main layer using a propylene-based resin composition (A) containing at least one β-crystal nucleating agent (B), and having two or more layers. There is no problem even if it has a multilayer structure. 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 form a laminated body having a so-called three-layer structure or four-layer structure in consideration of gas barrier properties.
As the gas barrier layer, among them, an ethylene-vinyl alcohol copolymer (EVOH), a metaxylylene adipamide polyamide resin, a conjugated diene polymer cyclized product and a mixture of an ethylene-vinyl alcohol copolymer are used. preferable.

  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 production method of the resin sheet, the components (A1), (A2), the β crystal nucleating agent (B) and the like are passed through a known single-screw or twin-screw extruder, and from a coat hanger die After extruding into a sheet, obtain by cooling and solidifying by pressing with an air knife, air chamber, hard rubber roll, steel belt, metal roll on the metal roll surface (with cooling water and oil circulating inside) Can do. 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 article of the present invention is obtained by solid-state pressure forming using a resin sheet having a propylene-based resin layer.
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.
In the thermoformed article of the present invention, such solid-state pressure forming is performed at a temperature lower than the melting peak temperature of the propylene-based resin composition (A) containing the β-crystal nucleating agent (B) of the main layer constituting the resin sheet. It is preferable to manufacture by plug 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 and the propylene-based resin composition is JIS K7210: 1999 “Method for testing plastic-thermoplastic plastic melt mass flow rate (MFR) and melt volume flow rate (MVR)”, Condition M (230 C., 2.16 kg load).

(2) Ethylene content:
The ethylene content in the ethylene-α-olefin copolymer component (A2) was measured by ¹³ C-NMR. However, when the propylene-based resin composition (A) is a propylene-ethylene block copolymer obtained by sequential polymerization, an ethylene-α-olefin copolymer is obtained by a method using a cross fractionator described in Japanese Patent No. 4705698. The content of the coalescence component (A2) was determined, and the ethylene content in the cross-fractionated ethylene-α-olefin copolymer component (A2) was measured by ¹³ C-NMR.

(3) 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.

(4) 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.

(5) β crystal fraction of the propylene-based resin layer:
The β crystal fraction of the propylene-based resin layer is determined according to “Makromol.,” By Turner Jones et al. According to the method described in “Chem 75, 135-137 (1964)”, the following formula was used. 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.

(6) 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.

(7) 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

(8) 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

(9) Molding temperature condition width:
For those with heat resistance of “◯”, the heater temperature settable 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.

(10) Impact resistance (drop test):
The obtained thermoformed container is filled with 270 CC of water, the mouth is heat sealed with a film, left in a refrigerator at 5 ° C. for 24 hours, then taken out of the refrigerator and immediately dropped. The drop height is 1.5m and 1.2m, and it is dropped many times until it breaks. N = 10, and the average of the number of times was evaluated. A thing with many times until it breaks is excellent in impact resistance. Those that did not break even if dropped 10 times were indicated as NB.

[2. Materials used]
(1) Propylene resin As propylene resins for the propylene resin composition (A), propylene resin compositions (PP1) to (PP11) comprising the following mixtures were used.

(PP1)
Propylene homopolymer (1): 50% by weight
MFR = 1.9 g / 10 min. Propylene-ethylene block copolymer (1): 50% by weight
Content of ethylene-propylene random copolymer component: 10% by weight
Ethylene content of ethylene-propylene random copolymer component: 60% by weight
MFR = 2.5 g / 10 min PP1 whole MFR = 2.2 g / 10 min Content of ethylene-propylene random copolymer component: 5% by weight
Melting point (Tm) = 164.3 ° C.

(PP2)
Propylene homopolymer (2): 50% by weight
MFR = 5.0 g / 10 min. Propylene-ethylene block copolymer (1): 20% by weight
Content of ethylene-propylene random copolymer component: 10% by weight
Ethylene content of ethylene-propylene random copolymer component: 60% by weight
MFR = 2.5 g / 10 min. Propylene-ethylene block copolymer (2): 30% by weight
Content of ethylene-propylene random copolymer component: 14% by weight
Ethylene content of ethylene-propylene random copolymer component: 49% by weight
MFR = 8.5 g / 10 min PP2 whole MFR = 5.1 g / 10 min Content of ethylene-propylene random copolymer component: 6.2 wt%
Melting point (Tm) = 162.7 ° C.

(PP3)
Propylene homopolymer (3): 50% by weight
MFR = 0.5 g / 10 min. Propylene-ethylene block copolymer (3): 50% by weight
Content of ethylene-propylene random copolymer component: 11% by weight
Ethylene content of ethylene-propylene random copolymer component: 60% by weight
MFR = 0.5 g / 10 min PP3 whole MFR = 0.5 g / 10 min Content of ethylene-propylene random copolymer component: 5.5 wt%
Melting point (Tm) = 165.0 ° C.

(PP4)
Propylene homopolymer (1): 95% by weight
MFR = 1.9 g / 10 min. Ethylene-propylene random copolymer: 5% by weight
Ethylene content of ethylene-propylene random copolymer component: 74% by weight
MFR (conforming to JIS K7210, 230 ° C., 2.16 kg) = 5.4 g / 10 minutes PP4 whole MFR = 2.0 g / 10 minutes Content of ethylene-propylene random copolymer component: 5.0% by weight
Melting point (Tm) = 164.3 ° C.

(PP5)
Propylene homopolymer (1): 90% by weight,
MFR = 1.9 g / 10 min. Ethylene-propylene random copolymer: 10% by weight,
Ethylene content of ethylene-propylene random copolymer component: 74% by weight
MFR (according to JIS K7210, 230 ° C., 2.16 kg) = 5.4 g / 10 minutes PP5 whole MFR = 2.1 g / 10 minutes Content of ethylene-propylene random copolymer component: 10.0% by weight
Melting point (Tm) = 164.3 ° C.

(PP6)
Propylene polymer (4): 90% by weight
Ethylene comonomer content: 0.3% by weight,
MFR = 0.5 g / 10 min. Ethylene-propylene random copolymer: 10% by weight,
Ethylene content of ethylene-propylene random copolymer component: 74% by weight
MFR (conforming to JIS K7210, 230 ° C., 2.16 kg) = 5.4 g / 10 minutes PP6 whole MFR = 0.6 g / 10 minutes Content of ethylene-propylene random copolymer component: 10.0% by weight
Melting point (Tm) = 160.3 ° C.

(PP7)
Propylene homopolymer (1): 90% by weight,
MFR = 1.9 g / 10 min. Ethylene-propylene random copolymer: 10% by weight,
Ethylene content of ethylene-propylene random copolymer component: 76% by weight
MFR (according to JIS K7210, 230 ° C., 2.16 kg) = 0.6 g / 10 minutes PP7 whole MFR = 1.7 g / 10 minutes Content of ethylene-propylene random copolymer component: 10.0% by weight
Melting point (Tm) = 164.3 ° C.

(PP8)
Propylene homopolymer (1): 90% by weight,
MFR = 1.9 g / 10 min. Propylene-ethylene block copolymer: 10% by weight
Content of ethylene-propylene random copolymer component: 54% by weight
Ethylene content of ethylene-propylene random copolymer component: 40% by weight
MFR = 0.8 g / 10 min PP8 whole MFR = 1.7 g / 10 min Content of ethylene-propylene random copolymer component: 5.4 wt%
Melting point (Tm) = 164.5 ° C.

(PP9)
Propylene homopolymer (1): 80% by weight
MFR = 1.9 g / 10 min. Propylene-ethylene block copolymer: 20% by weight
Content of ethylene-propylene random copolymer component: 54% by weight
Ethylene content of ethylene-propylene random copolymer component: 40% by weight
MFR = 0.8 g / 10 min PP9 whole MFR = 1.6 g / 10 min Content of ethylene-propylene random copolymer component: 10.8 wt%
Melting point (Tm) = 164.5 ° C.

(PP10)
Propylene homopolymer (1): 95% by weight
MFR = 1.9 g / 10 min. Ethylene-hexene random copolymer: 5% by weight
Ethylene content of ethylene-hexene random copolymer component: 82% by weight
MFR (according to JIS K7210, 230 ° C., 2.16 kg) = 4.1 g / 10 minutes PP10 whole MFR = 2.0 g / 10 minutes Content of ethylene-hexene random copolymer component: 5% by weight
Melting point (Tm) = 164.3 ° C.

(PP11)
Propylene homopolymer (1): 90% by weight,
MFR = 1.9 g / 10 min. Ethylene-hexene random copolymer: 10% by weight
Ethylene content of ethylene-hexene random copolymer component: 82% by weight
MFR (according to JIS K7210, 230 ° C., 2.16 kg) = 4.1 g / 10 minutes PP11 whole MFR = 2.1 g / 10 minutes Content of ethylene-hexene random copolymer component: 10% by weight
Melting point (Tm) = 164.3 ° C.

(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 wt% and PP1: 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 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 138.6 ° 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 PP2 was used instead of PP1.
The results are shown in Table 1.

(Example 3)
The same operation as in Example 1 was performed except that PP3 was used instead of PP1.
The results are shown in Table 1.

Example 4
The same operation as in Example 1 was performed except that PP4 was used instead of PP1.
The results are shown in Table 1.

(Example 5)
The same operation as in Example 1 was performed except that PP5 was used instead of PP1.
The results are shown in Table 1.

(Example 6)
The same operation as in Example 1 was performed except that PP6 was used instead of PP1.
The results are shown in Table 1.

(Example 7)
The same operation as in Example 1 was performed except that PP7 was used instead of PP1.
The results are shown in Table 1.

(Example 8)
The same operation as in Example 1 was performed except that PP8 was used instead of PP1.
The results are shown in Table 1.

Example 9
The same operation as in Example 1 was performed except that PP9 was used instead of PP1.
The results are shown in Table 2.

(Example 10)
The same operation as in Example 1 was performed except that PP10 was used instead of PP1.
The results are shown in Table 2.
(Example 11)
The same operation as in Example 1 was performed except that PP11 was used instead of PP1.
The results are shown in Table 2.

(Example 12)
The propylene-based resin pellets produced in Example 1 are put into an extruder with a screw diameter of 50 mm, and EVOH pellets (“BX6804B”, trade name, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) are introduced into an extruder with a screw diameter of 40 mm. In addition, an adhesive resin (“Modic P604V”, trade name, manufactured by Mitsubishi Chemical Co., Ltd., adhesive polypropylene resin) is introduced into another extruder with a screw diameter of 40 mm, and is heated and melt-plasticized at a resin temperature of 230 ° C. The polypropylene sheet obtained by extrusion and extrusion from a T-shaped die was continuously taken up at a speed of 1 m / min while being cooled and solidified by being sandwiched by a mirror-finished metal cast roll whose surface temperature was controlled at 80 ° C. Three-layer five-layer sheet of width 500 mm, EVOH layer thickness 0.1 mm, adhesive resin thickness 0.1 mm each, overall thickness 2.0 mm It 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 2.

(Example 13)
It implemented like Example 12 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 2.

(Example 14)
It implemented similarly to Example 12 except having used the mixture (brand name "Quintia" Nippon Zeon Co., Ltd. product) of the conjugated diene polymer cyclization product and the ethylene-vinyl alcohol copolymer instead of EVOH.
The evaluation results are shown in Table 2.

(Comparative Example 1)
Example 1 except that a β-crystal nucleating agent was not used and a propylene homopolymer (trade name “FY6H” manufactured by Nippon Polypro Co., Ltd.) having an MFR of 1.9 g / 10 min was used instead of PP1. It carried out like.
The evaluation results are shown in Table 3.

(Comparative Example 2)
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 3.

(Comparative Example 3)
Example 1 except that no β crystal nucleating agent was used and a propylene homopolymer (trade name “FY4” manufactured by Nippon Polypro Co., Ltd.) having an MFR of 5.0 g / 10 min was used instead of PP1. It carried out like.
The evaluation results are shown in Table 3.

(Comparative Example 4)
The same operation as in Example 1 was carried out except that no β crystal nucleating agent was used and PP2 was used instead of PP1.
The evaluation results are shown in Table 3.

(Comparative Example 5)
The same operation as in Example 1 was carried out except that no β crystal nucleating agent was used and PP3 was used instead of PP1.
The evaluation results are shown in Table 3.

  As is apparent from Tables 1 to 3 above, in the examples satisfying the provisions of the present invention, a thermoformed body with small shrinkage due to heat treatment assuming heat treatment in solid-state pressure forming was stably obtained. The thermoformed product obtained in the comparative example not satisfying the provisions of the present invention was a thermoformed product 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 the contents to be subjected to heat treatment, which contains 10 to 10,000 ppm of β-crystal nucleating agent (B) and satisfies the following (1) and (2) A method for producing a thermoformed article, comprising molding a resin sheet having a propylene-based resin layer made of the propylene-based resin composition (A) by a solid-state pressure forming method.
  (1) MFR (230 degreeC, 2.16kg load) is 0.1-100 g / 10min.
  (2) 60 to 99 parts by weight of the propylene polymer component (A1) and 40 to 1 part by weight of ethylene-α-olefin copolymer component (A2) containing 30 to 99.9% by weight of ethylene (provided that ( A1) and (A2) the total of the components is 100 parts by weight.) 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.