JP2013199098A - Multilayer thermoformed container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a multilayer thermoformed container with a label firmly fusion-bonded thereon, which is obtained by solid phase pressure forming of a polypropylene sheet at a temperature below a melting point.SOLUTION: A container with a label L firmly bonded thereon is obtained, by solid phase pressure forming of a specific ethylene-propylene copolymer layer and a polypropylene sheet S containing a polypropylene polymer layer, at a temperature below a melting point according to the plug-assist forming.

Description

  The present invention relates to a multilayer thermoformed container. More specifically, the present invention relates to a deep-drawn multilayer obtained by a so-called in-mold label attaching method in which a polypropylene sheet is solid-phase pressure-molded at a temperature below the melting point and simultaneously a label is attached to the container. The present invention relates to a thermoformed container.

  Conventionally, containers using thermoplastic resins such as polystyrene, polyethylene terephthalate, and polypropylene have been manufactured. Among thermoplastic resins, propylene-based polymers are excellent in heat resistance, rigidity, impact resistance, or hygiene, and thus are suitably used as containers for foods, and in particular, have 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.

  As a food container, a container having a long main body for storing contents with respect to the caliber of the container, that is, a so-called deep-drawn container, is effective in that the internal capacity can be increased as compared with the caliber. Such a deep drawn container may be formed by injection molding. Injection molding is suitable for obtaining deep-drawn containers with excellent design properties because of the advantage that it can be easily molded into the desired shape depending on the mold to be used. There is a problem that it is difficult to produce a thin molded product, which is slower than a thermoformed container.

Furthermore, in the commercialization stage, various printed labels are stuck at the same time as molding for the purpose of increasing the commercial value or displaying the contents or the like. The pasting of these labels has been conventionally carried out continuously by an automatic labeler machine or the like after molding of the container, but in recent years, these steps are omitted and the pasting is performed directly at the time of container molding. An in-mold labeling method is performed. Such an in-mold label attaching method is a suitable attaching method for containers such as blow molding and injection molding.

  On the other hand, after extruding a thermoplastic resin into a sheet, the sheet is reheated to obtain the desired container. Thermoforming methods such as vacuum forming, vacuum pressure forming, and solid pressure forming are easy to mold and productivity. Since it is high, it is suitable for mass production and it is easy to obtain multi-layered products.

  However, thermoforming methods in which the container is formed in a state where the sheet is melted, such as vacuum forming or vacuum / pressure forming, is reheated to a temperature equal to or higher than the melting point, so that the container is deep drawn (with a large depth / caliber ratio). It is difficult to obtain a container, and the thermoforming method in which the sheet is not melted (softened), such as solid-phase pressure forming, has the disadvantage that the label cannot be attached because the resin on the container surface is not melted. Have. Moreover, even when it is stuck, it has a drawback of easily peeling off.

  In view of the problems of the prior art, an object of the present invention is to obtain a so-called in-mold label application, which is obtained by solid-phase pressure forming a polypropylene sheet at a temperature below the melting point, and a label is attached to a container at the same time as molding. The present invention relates to a deep-drawn multilayer thermoformed container obtained by a deposition method, wherein the label is firmly attached.

  As a result of intensive studies in order to solve the above problems, the present inventors have obtained a multilayer polypropylene-based sheet containing a specific ethylene-propylene copolymer at a temperature equal to or lower than the melting point by solid-phase pressure forming with an in-mold label. Then, the label of the obtained container was found to be firmly attached, and the present invention was completed.

That is, the first feature of the present invention is that the outermost layer of the multilayer thermoformed container is a multilayer thermoformed container formed by an in-mold label attaching method using a polypropylene-based sheet and obtained by solid-phase pressure forming. Is an ethylene-propylene copolymer (A) that is polymerized using a metallocene catalyst and satisfies the following requirements (i) to (iv), and the main layer has the following requirements (v to vi). A multilayer thermoformed container characterized by having a deep drawing structure having a depth / caliber ratio of 1 or more, wherein a polypropylene-based polymer (B) satisfying (1) is used.
Requirement (i): Melt flow rate (MFR) (temperature 230 ° C., load 2.16 kg) is 1 to 20 g / 10 min.
Requirement (ii): The ratio (Q value) of weight average molecular weight (Mw) and number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is 1.5 to 3.5.
Requirement (iii): In temperature rising elution fractionation (TREF) with orthodichlorobenzene (ODCB), a component eluted at a temperature of 40 ° C. or less is 3.0% by weight or less.
Requirement (iv): Melting point measured by DSC is 140 ° C. or lower.
Requirement (v): Melt flow rate (MFR) (temperature 230 ° C., load 2.16 kg) is 0.2 to 5 g / 10 min.
Requirement (vi): Melting peak temperature (melting point) measured with a differential scanning calorimeter (DSC) is 160 ° C. or higher.

  The second feature of the present invention is that the thickness of the outermost layer of the polypropylene sheet is 20 to 200 μm, and the thickness ratio between the outermost layer and the main layer (outermost layer / main layer) is 0.2 or less. The multilayer thermoformed container is characterized by the above.

The third feature of the present invention is characterized in that at least one label is integrally attached to the outermost layer surface comprising the ethylene-propylene copolymer (A) constituting the multilayer thermoformed container. A multilayer thermoformed container.
A fourth feature of the present invention is a polypropylene sheet having a laminated structure including at least two layers of a main layer composed of a polypropylene polymer (B) and an outer layer composed of an ethylene-propylene copolymer (A). It is interposed between the thermoforming mold unit and the plug unit so as to be on the mold side, softened by heating to a temperature below the melting point of the main layer, and then the assist plug is pushed down, At the same time, the polypropylene sheet is pre-shaped into a container by solid-phase pressure forming, and then the air is applied to the pre-shaped part to closely adhere the polypropylene sheet along the inner surface of the mold, A solid-phase pneumatic plug assembly for a container with an in-mold label, wherein at least one label disposed in the mold is integrally attached. Door molding method, in the.

A fifth feature of the present invention is that air is blown in or air is discharged between the mold and the sheet, and the polypropylene sheet is brought into close contact with the inner surface of the mold and is disposed in the mold. A method for forming a solid-phase compressed air plug in a container with an in-mold label, wherein a deep-drawing structure is imparted to the container by affixing the attached label integrally.
A sixth feature of the present invention is that an in-feed mechanism comprising a plurality of thermoforming mold units and plug units arranged in a direction perpendicular to the traveling direction of the polypropylene sheet is arranged. A method for forming a solid-phase pressure plug assisted molding of a container with a mold label.

The multilayer thermoformed container of the present invention can be widely applied to food containers and the like that are particularly required to have design properties and contents display because the labels are firmly attached.
In particular, the present invention uses a specific polypropylene-based sheet and applies a solid-phase pressure forming method in plug-assist molding to it. Can be molded stably and easily with a high-speed cycle.

It is a front view of the multilayer thermoforming container of this invention. It is sectional drawing of the multilayer thermoforming container of this invention. FIG. 6 is a state diagram before pushing an assist plug in solid-state pressure forming. It is a state figure at the time of assist plug pushing in in solid phase pressure forming. It is a state figure at the time of air blowing in solid-phase pressure forming.

The multilayer thermoformed container of the present invention is a multilayer thermoformed container having a main body for storing contents and a label attached to the outer surface of the main body, and the outermost layer of the multilayer thermoformed container is polymerized using a metallocene catalyst. An ethylene-propylene copolymer (A) that satisfies the following requirements (i) to (iv) is used, and a polypropylene polymer (B) that satisfies the following requirements (v to vi) is used in the main layer. It has a deep drawing structure having a depth / caliber ratio of 1 or more, characterized in that it is used.
Requirement (i): Melt flow rate (MFR) (temperature 230 ° C., load 2.16 kg) is 1 to 20 g / 10 min.
Requirement (ii): The ratio (Q value) of weight average molecular weight (Mw) and number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is 1.5 to 3.5.
Requirement (iii): In temperature rising elution fractionation (TREF) with orthodichlorobenzene (ODCB), a component eluted at a temperature of 40 ° C. or less is 3.0% by weight or less.
Requirement (iv): Melting point measured by DSC is 140 ° C. or lower.
Requirement (v): Melt flow rate (MFR) (temperature 230 ° C., load 2.16 kg) is 0.2 to 5 g / 10 min.
Requirement (vi): Melting peak temperature (melting point) measured with a differential scanning calorimeter (DSC) is 160 ° C. or higher.

The multilayer thermoformed container of the present invention includes the outermost layer (L ₁ ) made of an ethylene-propylene copolymer (A) that satisfies the above requirements (i) to (iv), and the above requirements (v to vi). A main layer (L ₂ ) made of a polypropylene polymer (B) to be filled is composed of a polypropylene-based sheet having a laminated structure including at least two layers, and a label is integrally attached to a desired position of the outermost layer (L ₁ ). The container has a deep drawing structure in which the ratio of the depth (H) / the diameter (D) of the container is 1 or more. In this multilayer thermoformed container, the main layer (L ₂ ) constituting the inner surface of the container uses a specific polypropylene polymer (B), for example, boiling, overheating, bumping by a microwave oven or the like. Due to high temperature heating, there is no decrease in transparency due to softening, deformation, or alteration, and low molecular weight compounds do not elute into the contents of the container, so consideration of taste and hygiene is also expected.
On the other hand, the outermost layer (L ₁ ) constituting the outer surface of the container is formed with the main layer (L ₂ ) under a special condition of thermoforming by using a specific ethylene-propylene copolymer (A). There is no exfoliation, alteration due to heat, deformation, loss of transparency, etc., and the component that elutes at a temperature of 40 ° C. or less is about 3.0% by weight or less. In addition to the environment, there is no volatile matter between the label and the outermost layer, the inside surface of the cabinet and the contact surface of the outermost layer are kept relatively clean, and the label (L) is in very good condition. A unique function of being in close contact with each other can be expressed.

Thus, at least the specific polymer and copolymer of the outermost layer (L ₁ ) made of the ethylene-propylene copolymer (A) and the main layer (L ₂ ) made of the polypropylene polymer (B) were selected. Consisting of a polypropylene-based sheet with a laminated structure including two layers, it not only exhibits unique performance from the material aspect of the container, but in particular, in-mold label sticking solid-phase pressure forming and deep drawing at temperatures below the melting point Even in the case of being subjected to thermoforming, in the so-called container molding process, not only complete adhesion of the label (L) can be achieved, but also deterioration of moldability, peeling, opacification, reduction of mechanical strength, etc. This means that a laminated structure composed of the specific polymer and copolymer, which is physically and structurally harmful, also contributes to the molding of the container.
In addition, if the molding state is adjusted in consideration of the molding temperature conditions such as the melting point of the polymer and the copolymer and the molding conditions such as the molding speed in the pressure molding and deep drawing molding such as air blowing or decompression, Some operations such as stretching and orientation are added by the drawing, and the specific polymer and copolymer contained in the polypropylene polymer (B) are selected, when the plug is pushed in, the amount, and when the air is blown, the amount In addition to being closely related to the molding temperature, it is possible not only to adjust the wall thickness of the container and the bottom, but also to maintain or improve transparency, as well as to improve rigidity, mechanical strength, etc. There is expected.

Hereinafter, each item will be described sequentially.
I. Ethylene-propylene copolymer (A)
In the present invention, the ethylene-propylene copolymer (A) having the characteristics and properties shown in the requirements (i) to (iii) is used for the outermost layer of the polypropylene sheet.
Hereinafter, each item will be described sequentially.

Requirement (i) Melt flow rate (MFR):
As shown in the requirement (i), the ethylene-propylene copolymer (A) according to the present invention has a melt flow rate (MFR) of 1 to 20 g / 10 minutes measured at a temperature of 230 ° C. and a load of 2.16 kg. 2 to 15 g / 10 min, more preferably 3 to 10 g / 10 min.
When the melt flow rate (MFR) of the ethylene-propylene copolymer (A) is less than 1 g / 10 minutes, the melt fluidity is lowered and the container surface is roughened. On the other hand, if the MFR exceeds 20 g / 10 min, sheet forming may become difficult, for example, air winding during sheet forming or separation of the sheet from the roll may deteriorate.

The melt flow rate (MFR) is a test condition in accordance with JIS K6921-2 “Plastics—Polypropylene (PP) molding and extrusion materials—Part 2: How to make test pieces and properties”. : A value measured at 230 ° C. and a load of 2.16 kgf.
The melt flow rate (MFR) of the ethylene-propylene copolymer (A) is a chain transfer agent such as hydrogen that is added at the time of polymerization by adjusting the temperature and pressure which are the polymerization conditions of the ethylene-propylene copolymer (A). Adjustment can be easily performed by controlling the amount of addition.

Requirement (ii) Mw / Mn ratio (hereinafter referred to as Q value)
The ethylene-propylene copolymer (A) used in the present invention has a Q value in the range of 1.5 to 3.5, preferably 2 to 3.5, more preferably 2.5 to 3.3. It is.
The Q value is a value obtained as a ratio (Mw / Mn) between the weight average molecular weight (Mw) and the number average molecular weight (Mn) measured by gel permeation chromatography (GPC). Means that the smaller the molecular weight, the more uniform the molecular weight and the narrower the molecular weight distribution.
When the Q value of the ethylene-propylene copolymer (A) used in the present invention is less than 1.5, the surface of the sheet becomes rough. On the other hand, if the Q value exceeds 3.5, sticking to a portion other than the label attaching portion, that is, the outermost mold, occurs at the time of forming the container, making it difficult to take out the container.

  As a method for adjusting the Q value of the ethylene-propylene copolymer (A), it is effective to use a metallocene catalyst described later. In addition, polymerization is performed using a catalyst system in which two or more metallocene catalyst components are used in combination or a catalyst system in which two or more metallocene complexes are used in combination, or by performing multistage polymerization of two or more stages at the time of polymerization, the Q value is widened. Can be controlled. Conversely, in order to narrowly adjust the Q value, it can be adjusted by polymerizing the ethylene-propylene copolymer (A) and then melt kneading it using an organic peroxide.

The specific measurement of the Q value is obtained by measuring the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) under the following conditions.
GPC equipment: ISOC-ALC / GPC manufactured by Waters
Solvent: O-dichlorobenzene (ODCB)
Measurement temperature: 140 ° C
Flow rate: 1 ml / min
Standard material: Monodispersed polystyrene manufactured by Tosoh Corporation

The sample is prepared by preparing a 1 mg / mL solution using ODCB (containing 0.5 mg / mL BHT) and dissolving it at 140 ° C. for about 1 hour.
The baseline and section of the obtained chromatogram are performed as shown in FIG.
Further, the conversion from the retention capacity obtained by GPC measurement to the molecular weight is performed using a standard curve prepared in advance by standard polystyrene. The standard polystyrenes used are all the following brands manufactured by Tosoh Corporation.
Brand: F380, F288, F128, F80, F40, F20, F10, F4, F1, A5000, A2500, A1000
Inject 0.2 mL of a solution dissolved in ODCB (containing 0.5 mg / mL BHT) so that each is 0.5 mg / mL to create a calibration curve. The calibration curve uses a cubic equation obtained by approximation by the least square method.
The following numerical value is used for the viscosity formula: [η] = K × Mα used for conversion to molecular weight.
PS: K = 1.38 × 10 −4, α = 0.7
PP: K = 1.03 × 10−4, α = 0.78

Requirement (iii) Temperature rising elution fractionation (TREF) with orthodichlorobenzene (ODCB):
As shown in the requirement (iii), the ethylene-propylene copolymer (A) according to the present invention has 3 components that elute at a temperature of 40 ° C. or lower in an elution curve obtained by temperature-programmed elution fractionation (TREF) measurement. 0.0% by weight or less, preferably 2.0% by weight or less, and more preferably 1.0% by weight or less.
The
The component that elutes at a temperature of 40 ° C. or lower is a low crystalline component. If the amount of this component is large, the crystallinity of the entire product is lowered, and the mechanical strength such as the rigidity of the product is lowered. There is a risk of sticking the sheet to the mold during molding.
The temperature rising elution fractionation (TREF) of the ethylene-propylene copolymer (A) with orthodichlorobenzene (ODCB) can be generally kept low by using a metallocene complex during the copolymerization. In addition to keeping the purity of the catalyst at a certain level or higher, it is necessary that the catalyst production method and the reaction conditions at the time of polymerization are not extremely high, and that the amount ratio of the organoaluminum to the metallocene complex is not increased too much.

The details of the measurement method of the eluted component by temperature rising elution fractionation (TREF) are as follows.
A sample is dissolved in orthodichlorobenzene at 140 ° C. to obtain a solution. This is introduced into a 140 ° C. TREF column, cooled to 100 ° C. at a rate of 8 ° C./min, and then cooled to 40 ° C. at a rate of 4 ° C./min, and held for 10 minutes. Thereafter, orthodichlorobenzene as a solvent is caused to flow through the column at a flow rate of 1 mL / min, and components dissolved in 40 ° C orthodichlorobenzene are eluted in the TREF column for 10 minutes, and then the heating rate is 100 ° C / hour. The column is linearly heated to 140 ° C. to obtain an elution curve.
Column size: 4.3mmφ × 150mm
Column packing material: 100 μm surface inert treatment glass beads Solvent: Orthodichlorobenzene Sample concentration: 5 mg / mL
Sample injection volume: 0.1 mL
Solvent flow rate: 1 mL / min Detector: Fixed wavelength infrared detector, manufactured by FOXBORO, MIRAN, 1A
Measurement wavelength: 3.42 μm

Requirement (iv): Melting point measured by DSC The ethylene-propylene copolymer (A) used in the present invention has a melting peak temperature measured by a differential scanning calorimeter (DSC), which is a melting peak temperature. It needs to be 140 ° C. or lower, preferably 130 ° C. or lower.
When the melting point is 140 ° C. or higher, the label sticking strength decreases.
In order to adjust the melting point, it can be easily adjusted by controlling the amount of ethylene supplied to the polymerization reaction system.
In addition, the specific measurement of melting | fusing point uses DSC by Seiko Co., Ltd., took 10.0 mg of sample, hold | maintained at 200 degreeC for 5 minute (s), and made it crystallize at the temperature-fall rate of 10 degree-C / min to 40 degreeC, and also 10 degreeC The melting peak temperature when melted at a rate of temperature rise per minute was defined as the melting point (unit: ° C.).
The melting point of the ethylene-propylene copolymer (A) of the present invention is generally about 95 to 160 ° C., but it is an outer layer of the container and may melt when hot water is poured. Preferably, the one in the range of 110 to 140 ° C. is used arbitrarily, but when used for a coating layer that is an outer layer of an actual polypropylene sheet, the melting point is lower than that of the base material layer that is the main layer, and It is preferable to select a material having a difference of 20 ° C. or more, preferably having a difference of about 25 to 50 ° C.

2. Production method of ethylene-propylene copolymer (A) The ethylene-propylene copolymer (A) used in the present invention can be obtained by using a metallocene catalyst and carrying out copolymerization while paying attention to the production conditions. . At this time, the metallocene catalyst used may be one kind or a mixture of two or more kinds.
The metallocene catalyst is a catalyst using a complex of a group 4-6 transition metal such as titanium, zirconium, hafnium and the like and a cyclopentadienyl group or a cyclopentadienyl derivative group.
In the metallocene catalyst, as the cyclopentadienyl derivative group, an alkyl substituent such as pentamethylcyclopentadienyl or a group in which two or more substituents are combined to form a saturated or unsaturated cyclic substituent is used. Typically, an indenyl group, a fluorenyl group, an azulenyl group, or a partial hydrogenated product thereof can be given. Further, those in which a plurality of cyclopentadienyl groups are bonded by an alkylene group, a silylene group, a germylene group or the like are also preferably used.

Specific examples of the metallocene complex include the following compounds.
(1) Methylenebis (cyclopentadienyl) hafnium dichloride, (2) Methylene (cyclopentadienyl) (3,4-dimethylcyclopentadienyl) hafnium dichloride, (3) Isopropylidene (cyclopentadienyl) (3 , 4-dimethylcyclopentadienyl) hafnium dichloride, (4) ethylene (cyclopentadienyl) (3,5-dimethylpentadienyl) hafnium dichloride, (5) methylenebis (indenyl) hafnium dichloride, (6) ethylenebis (2-methylindenyl) hafnium dichloride, (7) ethylene 1,2-bis (4-phenylindenyl) hafnium dichloride, (8) ethylene (cyclopentadienyl) (fluorenyl) hafnium dichloride, (9) dimethylsilylene (Cyclope Tadienyl) (tetramethylcyclopentadienyl) hafnium dichloride, (10) dimethylsilylenebis (indenyl) hafnium dichloride, (11) dimethylsilylenebis (4,5,6,7-tetrahydroindenyl) hafnium dichloride, (12) Dimethylsilylene (cyclopentadienyl) (fluorenyl) hafnium dichloride, (13) Dimethylsilylene (cyclopentadienyl) (octahydrofluorenyl) hafnium dichloride, (14) Methylphenylsilylenebis [1- (2-methyl- 4,5-benzo (indenyl)] hafnium dichloride, (15) dimethylsilylenebis [1- (2-methyl-4,5-benzoindenyl)] hafnium dichloride, (16) dimethylsilylenebis [1- (2- Methyl-4 -Azulenyl)] hafnium dichloride, (17) dimethylsilylenebis [1- (2-methyl-4- (4-chlorophenyl) -4H-azurenyl)] hafnium dichloride, (18) dimethylsilylenebis [1- (2-ethyl) -4- (4-chlorophenyl) -4H-azulenyl)] hafnium dichloride, (19) dimethylsilylenebis [1- (2-ethyl-4-naphthyl-4H-azurenyl)] hafnium dichloride, (20) diphenylsilylenebis [ 1- (2-methyl-4- (4-chlorophenyl) -4H-azurenyl)] hafnium dichloride, (21) dimethylsilylenebis [1- (2-methyl-4- (phenylindenyl))] hafnium dichloride, 22) Dimethylsilylenebis [1- (2-ethyl-4- (phenylindene) Nyl))] hafnium dichloride, (23) dimethylsilylene bis [1- (2-ethyl-4-naphthyl-4H-azurenyl)] hafnium dichloride, (24) dimethylgermylene bis (indenyl) hafnium dichloride, (25) dimethyl Germylene (cyclopentadienyl) (fluorenyl) hafnium dichloride.

The same compounds as described above can be used for other Group 4, 5, 6 transition metal compounds such as a titanium compound and a zirconium compound. These compounds may be used in combination for the catalyst component and catalyst of the present invention.
In addition, compounds in which one or both of chlorides of these compounds are replaced with bromine, iodine, hydrogen, methylphenyl, benzyl, alkoxy, dimethylamide, diethylamide, an alkyl group, or the like can also be exemplified.
Furthermore, instead of the above-mentioned hafnium, compounds substituted for titanium, zirconium and the like can also be exemplified.
Of these, an ethylene-propylene random copolymer excellent in melt tension, transparency, and moldability is obtained, and a catalyst using hafnium that is less likely to cause rough skin is suitable for the present invention.

The co-catalyst is selected from the group consisting of an ionic compound capable of reacting with an aluminum oxy compound or a metallocene compound to convert the metallocene compound component into a cation or a Lewis acid, a solid acid, or an ion-exchange layered silicate. At least one compound is used.
Moreover, an organoaluminum compound can be added with these compounds as needed.
Examples of the aluminum oxy compound include methylalumoxane, ethylalumoxane, propylalumoxane, butylalumoxane, isobutylalumoxane, methylethylalumoxane, methylbutylalumoxane, methylisobutylalumoxane and the like. A reaction product of a trialkylaluminum and an alkylboronic acid can also be used. For example, 2: 1 reactant of trimethylaluminum and methylboronic acid, 2: 1 reactant of triisobutylaluminum and methylboronic acid, 1: 1: 1 reactant of trimethylaluminum, triisobutylaluminum and methylboronic acid, triethylaluminum and butylboron Such as a 2: 1 reactant of the acid.

As the ion-exchange layered silicate, silicates of smectite group such as montmorillonite, sauconite, beidellite, nontronite, saponite, hectorite, stevensite, bentonite, teniolite, vermiculite group, mica group and the like are used.
These silicates are preferably subjected to chemical treatment. Here, as the chemical treatment, any of a surface treatment for removing impurities adhering to the surface and a treatment that affects the crystal structure and chemical composition of the layered silicate can be used.
Specific examples include (i) acid treatment, (b) alkali treatment, (c) salt treatment, and (d) organic matter treatment. These treatments remove impurities on the surface, exchange cations between layers, elute cations such as Al, Fe, and Mg in the crystal structure, resulting in ion complexes, molecular complexes, organic derivatives, etc. The surface area, interlayer distance, solid acidity, etc. can be changed. These processes may be performed independently or two or more processes may be combined.
Moreover, you may use organoaluminum compounds, such as a triethylaluminum, a triisobutylaluminum, and diethylaluminum chloride, with these compounds as needed.
In the ethylene-propylene copolymer (A) used in the present invention, the preferred proportion of structural units derived from propylene (hereinafter referred to as “propylene units”) is 90 to 99.9% by weight in all the structural units. The structural unit derived from ethylene (hereinafter referred to as “ethylene unit”) is preferably 0.1 to 10% by weight.

  Examples of the propylene polymer (A) used in the present invention include “Wintech PP” manufactured by Nippon Polypro Co., Ltd.

The ethylene-propylene copolymer (A) used in the present invention can be used in combination with other α-olefins within a range not impairing the effects of the present invention. For example, butene-1, pentene-1, 3-methyl-1-butene, hexene-1, 3-methyl-1-pentene, 4-methyl-1-pentene, heptene-1, octene-1, nonene-1, Examples include decene-1, dodecene-1, tetradecene-1, hexadecene-1, octadecene-1, eicosene-1, and the like. These may be used alone or in combination of two or more.
Among them, butene-1 is preferable, and in the ethylene-propylene copolymer (A), the propylene unit is 90 to 99.9% by weight in all the structural units, and is derived from ethylene and α-olefin. The unit (hereinafter referred to as “comonomer unit”) is preferably an ethylene-butene-1-propylene ternary random copolymer of 0.1 to 10% by weight.

2. Other compounding agents In the ethylene-propylene copolymer (A) used in the present invention, other known polymers usually used for polyolefins are blended in a proportion of 0 to 50% by weight within a range not impairing the effects of the present invention. can do.
Examples of the other polymer include propylene alone or a copolymer of propylene and another α-olefin, polymers such as low density polyethylene and high density polyethylene, and various thermoplastic elastomers.

The ethylene-propylene copolymer (A) includes antioxidants, neutralizers, nucleating agents, light stabilizers, ultraviolet absorbers, inorganic fillers, antiblocking agents, lubricants, antistatic agents, metal inertness. Various additives that can be usually used for polypropylene, such as an agent, 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.

II. Polypropylene polymer (B)
In the present invention, the polypropylene polymer (B) is used in the main layer of the polypropylene sheet. The polypropylene polymer (B) has the properties and properties shown in the requirements (v) to (vi).
Requirement (v) Melt flow rate (MFR):
As shown in the requirement (v), the polypropylene polymer (B) according to the present invention has a melt flow rate (MFR) measured at a temperature of 230 ° C. and a load of 2.16 Kg of 0.2 to 5 g / 10 min. It is preferably 0.5 to 2 g / 10 minutes, more preferably 0.5 to 1 g / 10 minutes.
When the MFR is less than 0.2 g / 10 minutes, the melt fluidity is lowered and the rigidity may be lowered. On the other hand, if the MFR exceeds 5 g / 10 min, the drawdown at the time of forming the sheet becomes intense, making it difficult to form the sheet and lowering the forming temperature at the time of forming the container, which may reduce the adhesive strength of the label.
The melt flow rate (MFR) is a test condition in accordance with JIS K6921-2 “Plastics—Polypropylene (PP) molding and extrusion materials—Part 2: How to make test pieces and properties”. : A value measured at 230 ° C. and a load of 2.16 kgf.
The melt flow rate (MFR) of the polypropylene polymer (B) adjusts the temperature and pressure, which are the polymerization conditions of the polypropylene polymer (B), and the amount of chain transfer agent such as hydrogen added during polymerization. By controlling, adjustment can be easily performed.

Requirement (vi) Melting Point The polypropylene polymer (B) used in the present invention preferably has a melting point of 160 ° C. or higher, which is a melting peak temperature measured by a differential scanning calorimeter (DSC). The above is more preferable. When the melting point is less than 160 ° C., the rigidity and heat resistance of the container are lowered, and the molding temperature at the time of molding the container is lowered, which may make it difficult to fuse the feet.
In order to adjust melting | fusing point, it can adjust easily by controlling the quantity of copolymerization monomers, such as alpha-olefin supplied to a polymerization reaction system.
In addition, the specific measurement of melting | fusing point uses DSC by Seiko Co., Ltd., took 10.0 mg of sample, hold | maintained at 200 degreeC for 5 minute (s), and made it crystallize at the temperature-fall rate of 10 degree-C / min to 40 degreeC, and also 10 degreeC The melting peak temperature when melted at a rate of temperature rise per minute was defined as the melting point (unit: ° C.).

2. Production Method of Polypropylene Polymer (B) Examples of the polymerization catalyst for the polypropylene polymer (B) used in the present invention include a Ziegler-Natta type catalyst, a metallocene catalyst, and the like. In order to obtain a polymer having a melting point of, a magnesium chloride-supported Ziegler-Natta catalyst is preferred.
As a polymerization method of the polypropylene-based polymer (B) used in the present invention, 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 can be used not only in a single reactor but also in a plurality, and a plurality of polymerization methods can be used in combination.
The polypropylene polymer (B) used in the present invention includes a homopolymer of propylene, a random copolymer of propylene and α-olefin, and a block copolymer containing a copolymer rubber component of propylene and α-olefin. Examples of the combination include one type or a mixture of two or more types.

Examples of α-olefins used in these copolymers include ethylene, butene-1, pentene-1, hexene-1, 4-methyl-pentene-1, octene-1, and the like. Alternatively, two or more multi-component copolymers may be used.
Specifically, propylene-ethylene copolymer, propylene-butene-1 copolymer, propylene-ethylene-butene-1 copolymer, propylene-ethylene-pentene-1 copolymer, propylene-pentene-1 copolymer Examples thereof include various binary and ternary copolymers such as a copolymer, a propylene-hexene-1 copolymer, a propylene-4-methyl-pentene-1 copolymer, and a propylene-octene-1 copolymer. A ratio of α-olefin of about 0.5 to 20 mol% is sufficient.

The polypropylene polymer (B) used in the present invention is preferably a propylene homopolymer having a high melting point, and examples thereof include “NOVATEC PP” manufactured by Nippon Polypro.
The catalyst according to the present invention is subjected to a prepolymerization treatment consisting of a small amount of polymerization by bringing an olefin into contact therewith. 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. The amount of prepolymerization is preferably 0.01 to 100, more preferably 0.1 to 50 with respect to the catalyst component. Moreover, a catalyst component can also be added or added at the time of prepolymerization. It is also possible to wash after the prepolymerization.
In addition, a method of coexisting a polymer such as polyethylene or polypropylene, or a solid of an inorganic oxide such as silica or titania, at the time of contacting or after contacting each of the above components is also possible.

(2-1) Use of Catalyst / Propylene Polymerization As the polymerization mode, any mode can be adopted as long as the catalyst for olefin polymerization including the catalyst component and the monomer efficiently contact each other.
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, it is possible to carry out multistage polymerization of two or more stages.
In the case of slurry polymerization, a saturated aliphatic or aromatic hydrocarbon such as hexane, heptane, pentane, cyclohexane, benzene, toluene, or the like is used alone or as a polymerization solvent.

The polymerization temperature is 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. In particular, when bulk polymerization is used, the pressure is preferably 1.5 MPa or more, more preferably 2.0 MPa or more. The upper limit is preferably 4.0 MPa or less, more preferably 3.5 MPa or less.
Furthermore, when using vapor phase polymerization, 1.5 MPa or more is preferable, and 2.0 MPa or more is more preferable. The upper limit is preferably 2.5 MPa or less, more preferably 2.0 MPa or less.

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

In addition to the propylene monomer, copolymerization using an α-olefin having about 2 to 20 carbon atoms (excluding those used as a monomer) as a comonomer may be performed. The (total) comonomer content in the propylene-based polymer is in the range of 0 mol% or more and 20 mol% or less, and a plurality of the above-mentioned comonomers can be used. Specifically, they are ethylene, 1-butene, 1-hexene, 1-octene and 4-methyl-1-pentene.
Among these, in order to obtain the polypropylene polymer (B) according to the present invention in a good balance between melt properties and catalytic activity, it is preferable to use ethylene at 5 mol% or less. In order to obtain a polymer having particularly high rigidity, it is preferable to use ethylene so that ethylene contained in the polymer is 1 mol% or less, more preferably propylene homopolymerization.

2. Other compounding agents The polypropylene polymer (B) used in the present invention can be blended with other known polymers usually used for polyolefins.
Examples of the other polymer include propylene alone or a copolymer of propylene and another α-olefin, polymers such as low density polyethylene and high density polyethylene, and various thermoplastic elastomers.

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

III. Polypropylene sheet The polypropylene sheet used in the present invention is a multilayer sheet composed of at least an outermost layer using a propylene polymer (A) and a main layer using a polypropylene polymer (B). There is no problem even with the above multilayer structure. For example, even if a barrier sheet in which a barrier resin layer such as EVOH or PA and an adhesive layer are arranged between the main layer and the outermost layer or in the main layer, the content does not permeate or adsorb to the innermost layer. It is also possible to arrange a resin layer.
As described above, the propylene-based sheet of the present invention is a laminate having at least a two-layer structure including a base material layer that can be said to be a main layer constituting the container main body portion and a coating layer that can also be called an outermost layer constituting the outer layer portion of the container. Is the body. However, as an intermediate layer of these two layers or as an inner surface layer of the base material layer, ethylene-vinyl alcohol copolymer (EVOH), polyvinyl alcohol, polyvinylidene chloride (PVDC), maleic anhydride modified PP, high impact It is also possible to form a laminate having a so-called three-layer structure or four-layer structure in which various materials made of polystyrene (HIPS), amorphous polyethylene terephthalate, low-expanded polystyrene, and the like are stacked in consideration of gas barrier properties.

The thickness of the polypropylene-based sheet used in the present invention is preferably 0.3 to 4 mm, more preferably 0.5 to 3.5 mm, and particularly preferably 0.8 to 3 mm. If the thickness is much less than 0.3 mm, the rigidity of the container is impaired, and if the thickness is much more than 4 mm, sheet molding may be difficult.
Moreover, it is preferable that the thickness of the outermost layer of the polypropylene-type sheet | seat used by this invention is 20-200 micrometers, 40-150 micrometers is more preferable, 50-130 micrometers is more preferable. When the thickness of the outermost layer is less than 20 μm, the label sticking strength decreases, and when it is 200 μm or more, the rigidity of the container may be decreased.
Furthermore, the thickness ratio (outermost layer / main layer) of the outermost layer and the main layer of the polypropylene sheet used in the present invention is preferably 0.2 or less, more preferably 0.15 or less, and 0.1 The following is more preferable. When the thickness ratio between the outermost layer and the main layer exceeds 0.2, the rigidity of the container may be reduced.
The width of the polypropylene sheet is determined by the standard of the molding machine, and is determined by how many containers with in-mold labels are subjected to solid-phase pressure air plug assisted molding at one time. If necessary, it is sufficient to cut it to a predetermined width and use it.

Such a polypropylene sheet can be formed into a multi-layer polypropylene sheet using a feed block or a multi-manifold using a molding machine equipped with a plurality of extruders usually used for molding polypropylene.
As a specific method for producing a polypropylene sheet, an ethylene-propylene polymer (A) and a polypropylene polymer (B) are respectively passed through different known single-screw or twin-screw extruders, and then coated solder dies. After being extruded into a sheet form, it is obtained by being cooled and solidified by pressing with an air knife, an air chamber, a hard rubber roll, a steel belt, or a metal roll on the surface of a metal roll (in which cooling water or oil circulates). be able to. It is also possible to cool and solidify both sides of the sheet with a steel belt.
Among such sheet cooling methods, a method using metal rolls and / or steel belts on both sides of the sheet is the most preferable method because a sheet surface with less surface irregularities, that is, a sheet having excellent transparency can be obtained. .

IV. Multi-layer thermoformed container The multi-layer thermoformed container of the present invention is a multi-layer thermoformed container having a main body containing contents and a sticking label on the outer surface of the main body, obtained by solid-phase pressure forming using a polypropylene-based sheet. The peel strength measured by a testing machine is heat-sealed to 200 g / 15 mm or more, and the main body has a deep drawing structure having a depth / caliber ratio of 1 or more.
If the outline | summary of the shape of the container of this invention is demonstrated based on FIG. 1, the dimension corresponded to the internal diameter which can be said to be the magnitude | size of the opening of a container is represented as a diameter (D), If the dimension to the bottom is the depth (H), it means that H / D> 1 or more, and in the molding of a slightly deeper container than the size of the mouth of the container, the polypropylene system of the present invention The combination of the sheet, the solid pressure compression molding, and the plug assist molding exhibits an excellent function, and the container having the label completely adhered to the outer surface is molded.

The multilayer thermoformed container of the present invention is a squeeze that is a ratio of the (maximum) depth to the bottom surface of the container body and the (maximum) width (bore diameter) of the container body, regardless of whether the container shape is square or round. The ratio needs to be 1.0 or more, preferably 1.2 or more. Those having a drawing ratio of 1.0 or more are generally called deep-drawn containers and are obtained by plug-assisted solid-state pressure air forming, and are excellent in rigidity and impact strength of the container. Such an in-mold labeled container is difficult to obtain. However, a deep-drawn container with an in-mold label can be easily obtained by the configuration of the present invention.
The depth (H) to the bottom surface of the container body is 10 to 300 mm, and the diameter of the container body is 20 to 300 mm, which can be arbitrarily determined in consideration of the use of the container. However, since it is a deep-drawn container, the deep-drawing ratio is important, and the (maximum) depth (H) to the bottom of the container body and the (maximum) width (caliber) (D) of the container body The aperture ratio (H / D) is 1.0 or more, preferably 1.2 or more, but in some cases, such as 1.8, 2.0, 4.0, 5.0 at most Ultra deep bottom containers can be molded once, but if the drawing ratio increases, it becomes increasingly difficult to integrally bond the labels, and the bottom of the container may be destroyed during molding. There is also a risk that the yield will deteriorate.

  The multilayer thermoformed container with an in-mold label of the present invention is obtained by heat-sealing a label set in a mold at the time of container molding at the same time as thermoforming. The label needs to be strongly adhered to the main body, and it must be 200 g / 15 mm or more in peel strength measured by a tensile tester. When heat-sealing so that the peel strength is 200 g / 15 mm or more, the label does not peel off during the transfer or dropping of the container.

Such a multilayer thermoformed container can be obtained by using a polypropylene-based sheet, softening the sheet at a temperature not higher than the melting point of the main layer, and using a plug-assisted solid-state pressure forming machine usually used for forming a polypropylene sheet. Examples of the heating method in such molding include indirect heating, hot plate heating, and hot roll heating. When the molding is performed at a temperature exceeding the melting point of the sheet, the transparency, gloss, and thickness uniformity of the resulting multilayer thermoformed container are deteriorated, and the outermost layer adheres to the assist plug, making the molding impossible.
In the present invention, such solid-phase pressure forming is plug-assisted forming at a temperature lower than the melting point of the polypropylene polymer (B) of the main layer constituting the polypropylene sheet.

  The present invention is composed of a main layer substantially composed of a polypropylene-based polymer and an outer layer substantially composed of an ethylene-propylene copolymer, and a polypropylene-based sheet having a laminated structure, so that the outer layer is on the side of the mold, It is interposed between the thermoforming mold unit and the plug unit, softened by heating to a temperature below the melting point of the main layer, and then pushed down the assist plug to form the polypropylene sheet into a container shape. Preliminarily shaped into a container by solid-phase pressure molding, and subsequently, applied air pressure to the preshaped part to bring the polypropylene sheet into close contact with the mold and at the same time affix the label to the outermost layer. Of the container with an in-mold label, wherein the label is heat-sealed to 200 g / 15 mm or more in peel strength measured by a tensile tester The solid-phase pressure plug assist molding method has been achieved.

In the in-mold label container of the present invention, polypropylene, polyethylene, paper, or a laminate of these is used as the label material. Among these, polypropylene is preferable, and for the laminate label, a label obtained by laminating polypropylene on the surface to be welded to the container is preferably used. There is no particular limitation on the shape and size of the label. The label is fixed in advance in a predetermined position with the mold opened, for example, by vacuum suction, static electricity, an adhesive method, or the like. Then, a label is affixed on the surface of a container main body by shape | molding a container main body within this metal mold | die.
As a label to be stuck to the label sticking container of the present invention, generally, a base resin layer, a printed layer and an overcoat layer on the front surface side, and a fused surface on the contact surface with the container on the back side. A multilayer type label having a multilayer structure of three or more layers in which layers are formed is used. As a material of the laminated type base resin, generally, a synthetic paper type or a type made of a stretched film made of a thermoplastic resin such as crystalline polypropylene is used. Specifically, polypropylene, propylene-ethylene copolymer is used. And polyolefin resins such as high density polyethylene and medium density polyethylene, polyethylene terephthalate resin, polyvinyl chloride resin, polyamide resins such as nylon-6 and nylon-6,6, ABS resin, ionomer resin and the like. Preferably, it is a film having a melting point of 130 to 280 ° C., such as polypropylene, high-density polyethylene, and polyethylene terephthalate resin, and these resins can be used in combination of two or more. Among these resins, polypropylene resins are preferable from the viewpoint of chemical resistance and cost.
It is characterized in that at least one label is integrally attached to the outermost layer surface comprising the ethylene-propylene copolymer (A) constituting the multilayer thermoformed container, and the size and size of the label The size, shape, scale, pattern, attachment position, etc. can be arbitrarily determined in consideration of the size and shape of the container and the design of the label.
Of course, it may be difficult to properly place the label at a predetermined position in the mold of the label, but depending on the size and scale of the multilayer thermoformed container, it is not a single label. Considering the contents of the container, it can be arbitrarily determined as 1, 2, or 3.

  Alternatively, a film in which 8 to 80% by weight of inorganic or organic fine powder is blended with these resins, a film stretched in one or two directions by a known method, and a film coated with latex containing an inorganic filler on the surface Moreover, the film etc. which vapor-deposited or bonded aluminum etc. can be used conveniently.

  As the fusing layer, a layer laminated on the base resin with a thickness of generally 3 to 40 μm, preferably 3 to 15 μm is used. The printing layer and the overcoat layer are formed to have a normal printing thickness or an overcoat layer thickness. The thickness of these labels is usually in the thickness range of 40 to 250 μm, preferably in the thickness range of 50 to 200 μm. If the thickness is less than 40 μm, the in-mold labeling method makes it difficult to separate the stacked labels one by one in the sticking process, and the insertion of the label into the mold by the label inserter is not fixed at the normal position. Problems are likely to occur. On the other hand, if it exceeds 250 μm, the strength at the boundary between the container and the label is undesirably lowered even if the composition of the present invention is used. It is preferable to be integrated by in-mold molding also from the viewpoint of sticking strength. In particular, a heat seal resin having a melting point lower than the melting point of the material resin of the film on the back surface of the thermoplastic resin film containing the inorganic fine powder. A layer made of a multi-layer structure film is preferable, and a synthetic paper label obtained by stretching the multi-layer structure film at a temperature higher than the melting point of the heat-sealable resin and lower than the melting point of the inorganic fine powder-containing thermoplastic resin is preferable. . The heat-sealable resin layers of these labels are preferably embossed for the purpose of preventing the generation of blisters during in-mold molding.

The present invention will be specifically described with reference to the drawings. In detail, the multilayer thermoformed container of the present invention has a front structure as shown in FIG. 1 and a cross-sectional structure as shown in FIG. 2 and has dimensions of a diameter (D) and a depth (H). A container to which an in-mold label is attached. The molding method of the multilayer thermoformed container of the present invention will be described. FIG. 3 shows a state before the plug is pushed in, and a thermoforming mold unit (M) and an assist plug unit (with a label (L) set in advance). P) and a polypropylene sheet (S) are interposed between the three directions shown in the figure so that the outermost layer (S ₁ ) faces the mold (M) and is softened by heating (not shown). This heating is determined in consideration of the melting points of the outermost layer (S ₁ ) and the main layer (S ₂ ) of the polypropylene sheet (S). Next, as shown in FIG. 4, the assist plug (P) is pushed down in one direction as shown in the figure, so that the polypropylene sheet (S) is preformed to form a depression corresponding to a substantially container shape.

Subsequently, as shown in FIG. 5, the polypropylene sheet (S) is sandwiched between the mold (M) and the upper mold (U) so as to be in a sealed state, and then high-pressure air is blown (not shown) and preformed. The polypropylene-based sheet (S) is maintained in a state of being shaped by applying a load pressure at which it is brought into close contact with the inner surface of the predetermined mold of the mold (M). At this time, the label (L) is simultaneously attached to the container.
As shown in FIG. 2, the multilayer thermoformed container of the present invention is a container having no stepped portion between the label surface and the container surface.

FIG. 5 is the most typical embodiment in which high-pressure air is blown, but when air is interposed between the inner surface of the mold (M) and the polypropylene sheet (S), An advanced deep-drawn container that improves the performance of high-pressure air blow by simply escaping air by drilling an arbitrary number of exhaust holes and suction holes (not shown) in the bottom part of the cavity type (M). Can be molded. In some cases, a deep-drawn container can be formed by vacuum suction in which air is discharged by positive pressure reduction from the suction hole of the mold (M). The amount of high-pressure air blown in and the blow-in pressure are determined in consideration of the size of the container and the molding speed, but technically common sense is a pressure that does not damage the sheet instantaneously. The amount and pressure of plug assist molding can be used.
In order to improve the mechanical strength for maintaining the shape of the container by gripping or the like, a rib structure is provided at the necessary part of the container to strengthen it, and the inner surface of the mold (M) and the polypropylene sheet If air is present between (S), it may become an obstacle, and when forming a container where a pattern, an embossed pattern, a satin pattern or the like is to be decorated on a necessary part or part of the container, a mold (M ), Which is pre-engraved with the patterns on the inner surface, in the solid-phase pneumatic plug-assisted molding method for containers with in-mold labels using such a mold (M), discharge an appropriate amount of air. is important.
In the case of FIGS. 3 to 5, it is an example in which the thermoforming mold unit (M) and the assist plug unit (P) are arranged as one set, but actually, the traveling direction of the polypropylene sheet On the other hand, a number of shaping mechanisms composed of thermoforming mold units and plug units arranged in a perpendicular direction are arbitrarily arranged at one, three, eight and ten, so-called many at once. A solid-phase pressure plug assisted molding method for a container with an in-mold label is also possible.

V. Applications of multi-layer thermoformed containers The multi-layer thermoformed containers of the present invention are excellent in design and use when the contents are at high temperatures, so they are suitable for containers in various fields such as food containers, detergent containers, and medical containers. In particular, it can be widely used in the beverage food field.

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

1. Evaluation method (1) Melt flow rate (MFR) [unit: g / 10 min]:
The ethylene-propylene copolymer (A) and the polypropylene-based polymer (B) are prepared according to A of JIS K7210: 1999 “Plastic-thermoplastic melt mass flow rate (MFR) and melt volume flow rate (MVR) test methods”. Measured according to the method and condition M (230 ° C., 2.16 kg load).

(2) Melting point (Tm):
Using Seiko Instruments DSC6200, sheet-like ethylene-propylene copolymer (A) or polypropylene-based polymer (B) is packed into a 10 mg aluminum pan, and the temperature rise rate from room temperature to 200 ° C is 100 ° C / min. The temperature was raised at 20 ° C. at a rate of 10 ° C./min, and the temperature was lowered to 20 ° C. to obtain the crystallization temperature (Tc) as the maximum crystal peak temperature (° C.) when crystallized. The melting point (Tm) was determined as the maximum melting peak temperature (° C.) when the temperature was raised to 200 ° C. per minute.
(3) Molecular weight and molecular weight distribution (Mw, Mn, Q value):
It was measured by the method described in the present specification by gel permeation chromatography (GPC).

(4) 40 ° C. soluble matter:
The 40 ° C. soluble component is as described in the present specification using the following apparatus.
(I) TREF part TREF column: 4.3 mmφ × 150 mm stainless steel column Column filler: 100 μm surface inactive glass beads Heating method: Aluminum heat block Cooling method: Peltier element (Peltier element is cooled by water)
Temperature distribution: ± 0.5 ° C
Temperature controller: Chino Corporation Digital Program Controller KP1000 (Valve Oven)
Heating method: Air bath oven Measurement temperature: 140 ° C
Temperature distribution: ± 1 ° C
Valve: 6-way valve 4-way valve (ii) Sample injection part Injection method: Loop injection method Injection amount: Loop size 0.1ml
Inlet heating method: Aluminum heat block Measurement temperature: 140 ° C

(Iii) Detection unit Detector: Fixed wavelength infrared detector MIRAN 1A manufactured by FOXBORO
Detection wavelength: 3.42 μm
High-temperature flow cell: Micro flow cell for LC-IR Optical path length 1.5mm Window shape 2φ x 4mm oval Synthetic sapphire window Measurement temperature: 140 ° C
(Iv) Pump unit Liquid feed pump: SSC-3461 pump manufactured by Senshu Kagaku Co. (v) Measurement conditions Solvent: o-dichlorobenzene (including 0.5 mg / mL BHT)
Sample concentration: 5 mg / mL
Sample injection volume: 0.1 mL
Solvent flow rate: 1 mL / min

(5) Mold adhesion The container was molded using the polypropylene-based sheet obtained in each example, and it was confirmed whether or not a fused product to the mold was generated.
○: No adhesion △: Slightly occurs, but molding is possible ×: Adhesion occurs and molding is impossible

(6) Label peeling strength Adhesive strength of the label to the container: The label fused to the container is cut into a width of 15 mm, and the adhesive strength between the label and the container is measured using a tensile tester “Autograph AGS-D manufactured by Shimadzu Corporation. It was determined by peeling the T-shape using a “shape” at a tensile speed of 300 mm / min. The criteria for label usage are as follows.
300 (g / 15 mm) or more: No practical problem.
200 to 300 (g / 15 mm): Adhesion is slightly weak, but there is no practical problem.
Less than 200 (g / 15 mm): This is a practical problem.

2. Materials used (1) Propylene polymer WFX4T for outer layer: Propylene polymer (A)
Propylene-ethylene random copolymer manufactured by Nippon Polypro Co., Ltd. (using metallocene catalyst, MFR = 7 g / 10 min, Q value = 2.8, soluble content of 40 ° C. or less by TREF = 1.8 wt%, melting point = 125 ° C.)
WFX6: Propylene polymer (A)
Propylene / ethylene random copolymer manufactured by Nippon Polypro (using metallocene catalyst, MFR = 2g / 10min, Q value = 2.8, 40 ° C. or less soluble content by TREF = 1.6 wt%, melting point = 125 ° C.)
WFW4: Propylene polymer (A)
Propylene / ethylene random copolymer manufactured by Nippon Polypro (using metallocene catalyst, MFR = 2g / 10min, Q value = 2.8, 40 ° C. or less soluble content by TREF = 1.6 wt%, melting point = 135 ° C.)
WSX02:
Propylene / ethylene random copolymer manufactured by Nippon Polypro Co., Ltd. (using metallocene catalyst, MFR = 25 g / 10 min, Q value = 2.6, 40 ° C. or lower soluble content by TREF = 1.7 wt%, melting point = 128 ° C.)
WFW5T:
Propylene-ethylene random copolymer (manufactured by Nippon Polypro Co., Ltd. (using metallocene catalyst, MFR = 7 g / 10 min, Q value = 2.8, soluble content below 40 ° C. by TREF = 2.8 wt%, melting point = 145 ° C.))
FX4G:
Propylene / ethylene random copolymer (manufactured by Nippon Polypro Co., Ltd., using Ziegler catalyst, MFR = 5 g / 10 min, Q value = 4.5, 40 ° C. or less soluble content by TREF = 17.1 wt%, melting point = 128 ° C.)
PP-1 (Propylene-based resin obtained in Production Example 1 below):
(Using metallocene catalyst, MFR = 2 g / 10 min, Q value = 4.0, 40 ° C. or less soluble content by TREF = 2.2 wt%, melting point = 125 ° C.)

(Production Example 1)
(I) Synthesis of metallocene compound Synthesis of (r) -dichloro [1,1′-dimethylsilylenebis {2-methyl-4- (4-chlorophenyl) -4H-azurenyl}] hafnium is disclosed in JP-A-11-240909. It carried out according to the method as described in the gazette.

(Ii) Preparation of chemically treated ion-exchange layered silicate Slowly add 3.75 liters of distilled water followed by 2.5 kg of concentrated sulfuric acid (96%) to a 10-liter glass separable flask equipped with a stirring blade did. At 50 ° C., 1 kg of montmorillonite (Mizusawa Chemical Co., Ltd. Benclay SL) was further dispersed, the temperature was raised to 90 ° C., and the temperature was maintained for 6.5 hours. After cooling to 50 ° C., the slurry was filtered under reduced pressure to recover the cake. 7 liters of distilled water was added to this cake, and after reslurry, it was filtered. This washing operation was performed until the pH of the washing liquid (filtrate) exceeded 3.5.
The collected cake was dried at 110 ° C. overnight under a nitrogen atmosphere. The weight after drying was 705 g of chemically treated silicate.
The silicate previously chemically treated was further dried with a kiln dryer. The specifications and conditions of the dryer are as follows.
Rotating cylinder: cylindrical shape, inner diameter 50 mm, humidification zone 550 mm (electric furnace), rotation speed with lifting blade: 2 rpm, tilt angle: 20/520, silicate feed rate: 2.5 g / min, gas flow rate: nitrogen, 96 liters / hour, countercurrent drying temperature: 200 ° C. (powder temperature)

(Iii) Preparation of solid catalyst In a metal reactor equipped with a stirrer with an internal volume of 13 liters, 0.20 kg of the dried silicate obtained above and 0.74 liters of Nitsubishi Mitsubishi Corporation heptane (hereinafter referred to as heptane). In addition, 1.26 liters of a heptane solution of trinormal octyl aluminum (0.04M) was added, and the system temperature was maintained at 25 ° C. After the reaction for 1 hour, it was thoroughly washed with heptane to prepare 2.0 liters of a silicate slurry.
0.80 liters of heptane was added to 2.44 g (3.30 mmol) of (r) -dichloro [1,1′-dimethylsilylenebis {2-methyl-4- (4-chlorophenyl) -4H-azulenyl}] hafnium, A mixture obtained by adding 33.1 ml of a heptane solution of triisobutylaluminum (0.71 M) and reacting at room temperature for 1 hour is added to the silicate slurry, and after stirring for 1 hour, 5.0 heptane is added and 5.0 liter is added. Adjusted.
Subsequently, at a temperature of 40 ° C., propylene was supplied at a rate of 100 g / hour, and prepolymerization was performed for 4 hours. Further polymerization was carried out for 1 hour.
After completion of the prepolymerization, the residual monomer was purged, and the catalyst was thoroughly washed with heptane. Subsequently, 0.17 L of heptane solution of triisobutylaluminum was added, followed by drying under reduced pressure at 45 ° C. By this operation, 0.60 kg of a dried prepolymerized catalyst was obtained.

(Iv) Polymerization The inside of a stirred autoclave with an internal volume of 200 liters was sufficiently replaced with propylene, and then 500 ml (0.12 mol) of triisobutylaluminum / n-hexane solution, 2.3 NL of hydrogen were added, and 1.1 of ethylene was added. 94 kg was added, and 45 kg of liquefied propylene sufficiently dehydrated was introduced. The temperature was raised to 40 ° C., and 2.2 g of the prepolymerized catalyst prepared in Production Example 1 was injected with argon. The temperature was raised to 62 ° C. over 40 minutes, and polymerization was carried out for 2 hours under these conditions. Thereafter, 100 ml of ethanol was injected to stop the reaction, the remaining gas was purged, and the product was dried to obtain a propylene / ethylene random copolymer (PP1 powder).
(V) Tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4-hydroxyphenyl) as an antioxidant with respect to 100 parts by weight of the obtained propylene homopolymer (PP1 powder) ) Propionate] 0.05 parts by weight of methane (manufactured by Ciba Specialty Chemicals, trade name Irganox 1010), tris- (2,4-di-t-butylphenyl) phosphite (manufactured by Ciba Specialty Chemicals) , 0.05 parts by weight of trade name Irgaphos 168), mixed at 750 rpm with a Henschel mixer for 1 minute, pelletized at an extrusion temperature of 230 ° C. using a 50 mmφ single screw extruder, and propylene resin (PP-1 )

(2) Main layer propylene polymer EA9H: polypropylene polymer (B)
Propylene polymer manufactured by Nippon Polypro Co., Ltd. (MFR = 0.5 g / 10 min, melting point 166 ° C.)
FY6H: Polypropylene polymer (B)
Propylene polymer manufactured by Nippon Polypro Co., Ltd. (MFR = 2.5 g / 10 min, melting point 162 ° C.)
EG7FTB:
Propylene / ethylene random copolymer (MFR = 1.3 g / 10 min, melting point 152 ° C.) manufactured by Nippon Polypro Co., Ltd.
MA3:
Propylene polymer manufactured by Nippon Polypro Co., Ltd. (MFR = 1.9 g / 10 min, melting point 165 ° C.)

[Example 1]
The polypropylene sheet obtained by feeding the EA9H pellets into an extruder with a screw diameter of 50 mm, feeding the WFX4T pellets into an extruder with a screw diameter of 40 mm, heat-melt plasticizing at a resin temperature of 230 ° C., and extruding from a T-die Is taken up at a speed of 1 m / min while being cooled and solidified with a mirror-finished metal cast roll whose surface temperature is controlled at 60 ° C., width 500 mm, WFX4T layer thickness 0.1 mm, overall thickness A 1.6 mm type 2 two-layer sheet was obtained.
Label: A rectangular label of ITE105 (manufactured by Yupo Corporation, thickness 105 micrometers, length 40 mm, width 60 mm) was used. In addition, the label was previously attached to the mold with a double-sided tape so that the label was attached to the surface of the container.
Next, this sheet is set between the thermoforming mold unit and the plug unit so that the WFX4T layer becomes the outer surface, the sheet is softened at a heater temperature of 320 ° C., and then a solid-state pressure forming machine RDM-50K. A multilayer thermoformed container was formed by (Irich Co.).
Various evaluations described above were performed on this multilayer thermoformed container. The results are shown in Table 1.

[Example 2]
It implemented similarly to Example 1 except having used WFX6 instead of WFX4T. The evaluation results are shown in Table 1.
[Example 3]
It implemented similarly to Example 1 except having used WFW4 instead of WFX4T. The evaluation results are shown in Table 1.
[Example 4]
It implemented like Example 1 except having used FY6H instead of EA9H. The evaluation results are shown in Table 1.
[Example 5]
The same operation as in Example 1 was performed except that the thickness of the WFX4T layer was 0.02 mm. The evaluation results are shown in Table 1.
[Example 6]
The same operation as in Example 1 was performed except that the thickness of the WFX4T layer was 0.4 mm. The evaluation results are shown in Table 1.
[Comparative Example 1]
It implemented like Example 1 except having used WSX02 instead of WFX4T. Table 2 shows the evaluation results of the fact that roll adhesion was severe during sheet forming and sheet formation was impossible.
[Comparative Example 2]
It implemented like Example 1 except having used PP-1 instead of WFX4T. The evaluation results are shown in Table 2.
[Comparative Example 3]
It implemented similarly to Example 1 except having used FX4G instead of WFX4T. The evaluation results are shown in Table 2.
[Comparative Example 4]
It implemented similarly to Example 1 except having used WFW5T instead of WFX4T. The evaluation results are shown in Table 2.
[Comparative Example 5]
It implemented similarly to Example 1 except having used EG7FTB instead of EA9H. The evaluation results are shown in Table 2.
[Comparative Example 6]
It implemented similarly to Example 1 except having used MA3 instead of EA9H. The drawdown during sheet molding was severe and sheet molding was impossible. The evaluation results are shown in Table 2.

As apparent from Table 1 above, in Examples 1 to 6 that satisfy all the configurations of the present invention, a multilayer thermoformed container in which the label was completely fused by solid-state pressure forming was stably obtained. On the other hand, in Comparative Examples 1 to 6 that do not satisfy the configuration of the present invention, the obtained multilayer thermoformed container is unstable in molding or incompletely fused with a label, and is subjected to heat treatment or transportation such as retort. It was a multilayer thermoformed container in which label peeling occurred due to impact.

The multilayer thermoformed container of the present invention is an excellent design property by solid-phase pressure forming, and is a container in which a label is completely fused. Therefore, the multilayer thermoformed container can be widely used in the field of food containers and beverage containers that require design properties. it can. Therefore, the industrial applicability is very large.

D: Diameter of container H; Depth of container L ₁ ; Outermost layer L ₂ ; Main layer L; Label M; Cavity type P; Assist plug S; Polypropylene sheet U; Upper mold unit 1; ; Polypropylene sheet transfer direction 3; Upper mold unit operation direction 4; Air blowing

Japanese Patent Laid-Open No. 3-73332 Japanese Patent Laid-Open No. 4-14420 JP 2000-319407 A JP 2001-30342 A

Claims (6)

In a multilayer thermoformed container formed by an in-mold label sticking method, obtained by solid-phase pressure molding using a polypropylene sheet, the outermost layer of the multilayer thermoformed container is polymerized using a metallocene catalyst The ethylene-propylene copolymer (A) satisfying the requirements (i) to (iv) is used, and the polypropylene polymer (B) satisfying the following requirements (v to vi) is used for the main layer. A multilayer thermoformed container characterized by having a deep-drawing structure having a depth / diameter ratio of 1 or more.
Requirement (i): Melt flow rate (MFR) (temperature 230 ° C., load 2.16 kg) is 1 to 20 g / 10 min.
Requirement (ii): The ratio (Q value) of weight average molecular weight (Mw) and number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is 1.5 to 3.5.
Requirement (iii): In temperature rising elution fractionation (TREF) with orthodichlorobenzene (ODCB), a component eluted at a temperature of 40 ° C. or less is 3.0% by weight or less.
Requirement (iv): Melting point measured by DSC is 140 ° C. or lower.
Requirement (v): Melt flow rate (MFR) (temperature 230 ° C., load 2.16 kg) is 0.2 to 5 g / 10 min.
Requirement (vi): Melting peak temperature (melting point) measured with a differential scanning calorimeter (DSC) is 160 ° C. or higher.   2. The multilayer according to claim 1, wherein the thickness of the outermost layer of the polypropylene sheet is 20 to 200 μm, and the thickness ratio of the outermost layer to the main layer (outermost layer / main layer) is 0.2 or less. Thermoformed container.   The multilayer according to claim 1 or 2, wherein at least one label is integrally attached to the outermost layer surface made of the ethylene-propylene copolymer (A) constituting the multilayer thermoformed container. Thermoformed container.   Thermoforming a polypropylene sheet having a laminated structure including at least two layers of a main layer composed of a polypropylene polymer (B) and an outer layer composed of an ethylene-propylene copolymer (A) so that the outer layer is on the mold side. Interposed between the mold unit and the plug unit for use, softened by heating to a temperature below the melting point of the main layer, and then pushed down the assist plug to form the polypropylene sheet by solid-state pressure molding Pre-shaped into a container shape, and subsequently, applying air pressure to the pre-shaped portion to closely contact the polypropylene sheet along the inner surface of the mold, and at least disposed in the mold A method for forming a solid-phase pneumatic plug-assist of a container with an in-mold label, wherein a single label is integrally attached.   By injecting air into the pre-shaped part or discharging air between the mold and the sheet, the polypropylene sheet is brought into close contact with the inner surface of the mold, and at the same time, the label disposed in the mold. The solid-phase pressure air plug assist molding method for a container with an in-mold label according to claim 4, wherein a deep-drawing structure is imparted to the container by sticking together. 6. The in-mold according to claim 4, wherein a plurality of shaping mechanisms comprising a thermoforming mold unit and a plug unit arranged in a direction perpendicular to the traveling direction of the polypropylene-based sheet are arranged. Solid phase pressure plug assist molding method for labeled containers.