JP4944058B2 - Polypropylene resin sheet and polypropylene resin container - Google Patents

Description

  The present invention relates to a polypropylene resin sheet and a polypropylene resin container, and particularly relates to a polypropylene resin sheet excellent in mechanical strength, transparency, and thermoformability, and a container obtained by thermoforming a polypropylene resin sheet.

  Thermoplastic resins such as polyvinyl chloride resin, polystyrene resin, and polypropylene resin are used in various packaging materials. In molding of these packaging materials, extrusion molding is performed by heating the thermoplastic resin and extruding it into a sheet. The obtained resin sheet is reheated and subjected to secondary processing by a thermoforming method such as vacuum forming or vacuum / pressure forming, and the thermoforming method such as vacuum forming has a high productivity. It is widely used as a molding method especially for mass production because it is high and can meet a large amount of demand.

Polypropylene resins, on the other hand, are excellent in heat resistance, mechanical strength, impact resistance, and hygiene, and are suitable for packaging materials such as packaging containers. Etc., there is a problem that the transparency is inferior compared with the case where amorphous resin such as polyvinyl chloride resin or polystyrene resin is thermoformed.
As a method for improving the transparency of the polypropylene resin, a method of copolymerizing with an olefin such as ethylene or a method of adding a crystal nucleating agent is used. While the transparency can be improved to some extent, the strength tends to be impaired.For example, when a container having a rectangular bottom shape of the container main body or a top surface of the lid is manufactured from a polypropylene resin sheet, this bottom surface part. Further, there is a problem that the strength (hereinafter also referred to as “waist strength”) when compressed in the direction in which the central portions of the opposing sides of the top surface portion are close to each other is weak, and the strength of the container is weak.
Particularly in recent years, there has been a demand for the development of a container having both strength and transparency with as few raw materials as possible in consideration of the environment, and there is a strong demand for the solution of the above problems.

To solve such a problem, a polypropylene resin for sheet molding containing a polypropylene resin having a MFR of 0.1 to 20 g / 10 min and a propylene / α-olefin copolymer having the same MFR as the polypropylene resin in a specific ratio. A composition is known (see Patent Document 1 below).
Patent Document 1 below describes that a polypropylene resin sheet having both strength and transparency can be obtained.

  However, since molded articles such as containers obtained by molding such a polypropylene resin sheet become thinner by molding, etc., the molded article obtained by molding a thin polypropylene resin sheet It is difficult to give sufficient waist strength.

JP 2006-193606 A

  The present invention can produce a container having a thin lid or container body by conventional thermoforming, and has strength such as waist strength that can withstand practical use against a molded article such as the produced container. An object of the present invention is to provide a polypropylene resin sheet capable of imparting characteristics with excellent transparency, and a container having excellent transparency and strength that can withstand practical use while being thinned.

  As a result of intensive studies to achieve the above object, the present inventors have obtained that a metallocene catalyst having an MFR value smaller than that of the polypropylene resin is used for a polypropylene resin having an MFR of 1 to 5 g / 10 min. By using a resin composition containing a crystal nucleating agent in a predetermined ratio with respect to a resin component containing the obtained random copolymer polypropylene resin in a specific ratio, the moldability is excellent, and the strength and transparency In order to complete the present invention, it was found that a thin-walled sheet having a combination of the above-mentioned thickness, a container formed using the thinned sheet has a strength that can withstand practical use, and is excellent in transparency. It came.

That is, the present invention is a polypropylene resin sheet obtained by extrusion-molding a resin composition containing 0.01 to 1 part by weight of a crystal nucleating agent with respect to 100 parts by weight of a resin component containing a polypropylene resin. The resin component includes at least one polypropylene resin polymerized by a Ziegler-Natta catalyst having an MFR value measured at a temperature of 230 ° C. and a load of 2.16 kg of 1 to 5 g / 10 minutes. The resin component contains more than 60% by weight and 95% by weight or less, and the resin component has a MFR value smaller than that of the first component polypropylene resin and has a metallocene catalyst. A second component composed of one or more random copolymerized polypropylene resins polymerized by 5 to 40% by weight. Moreover, the flexural modulus in the extrusion direction of the extrusion sheet molding, said extrusion direction seat width bent in the direction modulus orthogonal to the both 2000MPa or more 2400MPa below haze is 15% or less Provided are a polypropylene resin sheet and a polypropylene resin container using such a polypropylene resin sheet.

The polypropylene-based resin sheet of the present invention can be produced by conventional thermoforming of a container having a thin lid or container body, and can withstand practical use for a molded product such as a produced container. Strength properties such as waist strength can be imparted with excellent transparency.
In addition, the polypropylene resin container of the present invention can be formed in a state having both strength and transparency while being thinned.

First, a polypropylene resin sheet will be described as an embodiment of the present invention.
The polypropylene resin sheet of this embodiment contains a resin component containing a polypropylene resin in a resin composition as a raw material, and a crystal nucleating agent.
The resin component and the crystal nucleating agent are contained in the resin composition such that the crystal nucleating agent is in a proportion of 0.01 to 1 part by weight with respect to 100 parts by weight of the resin component. .

  The resin component has a MFR value smaller than the first component composed of one or more polypropylene resins having an MFR value of 1 to 5 g / 10 min, and the first component polypropylene resin, And a second component composed of at least one random copolymer polypropylene resin polymerized by a metallocene catalyst, wherein the first component is more than 60 wt% and not more than 95 wt% in the resin component. The second component is contained in the resin component in a proportion of 5 wt% or more and less than 40 wt%.

  The MFR values of the first component polypropylene resin and the second component polypropylene resin are both in accordance with JIS K7210 under conditions of a temperature of 230 ° C. and a load of 2.16 kg (“Condition M in JIS K7210”). )).

The MFR of the first component polypropylene-based resin is set to any value within the range of 1 to 5 g / 10 min. When the MFR exceeds the above range and becomes a large value, the melt tension is insufficient. This is because it becomes difficult to form an extruded sheet, and conversely, if the value is smaller than the above range, a flow failure may occur during the extrusion sheet forming and the polypropylene resin sheet may have a thickness variation.
From the viewpoint of workability in this extrusion sheet molding, it is possible to employ any polypropylene resin within the range of MFR 1.5 to 4 g / 10 min as the first component polypropylene resin in this embodiment. preferable.

The first component may be composed of a plurality of types of polypropylene resins having the same MFR value or different MFR values as long as the MFR value falls within the above range.
In addition, the polypropylene resin used for the first component is not particularly limited to the monomer species, and for example, a polypropylene resin in which propylene is homopolymerized, or a random copolymer of propylene and an α-olefin. (Random copolymer polypropylene resin) or the like can be employed.
Thus, for example, a polypropylene resin having an MFR in the range of 1 to 5 g / 10 min and a random copolymer polypropylene having an MFR in the range of 1 to 5 g / 10 min. It is also possible to constitute the first component with a system resin.

  In the present specification, the term “α-olefin” is used in the meaning including ethylene. Examples of the α-olefin constituting the random copolymer polypropylene resin include ethylene, butene-1, and pentene. -1, hexene-1, 4-methyl-pentene-1, and the like.

  The polypropylene resin used for the first component is either a polypropylene resin or a random copolymer polypropylene resin in which propylene and ethylene are randomly copolymerized and contain 99.0% by weight or more of propylene. It is preferable that a polypropylene resin is particularly preferable.

  The polypropylene resin used for the first component can be obtained by using a highly stereoregular polymerization catalyst. As the high stereoregular polymerization catalyst used for the polymerization of the polypropylene resin of the first component, A so-called Ziegler-Natta catalyst using a titanium compound prepared using titanium, alkoxytitanium or the like as a starting material can be mentioned.

  As a polymerization mode of the polypropylene-based resin, any method can be adopted as long as the catalyst component and the monomer come into efficient contact. Specifically, the slurry method using an inert solvent, the bulk method using propylene as a solvent substantially without using an inert solvent, the solution polymerization method, or the monomers are substantially gaseous without using a liquid solvent substantially. It is possible to employ a gas phase method that keeps the temperature constant.

  Continuous polymerization and batch polymerization can also be applied. In the case of slurry polymerization, a saturated aliphatic or aromatic hydrocarbon such as hexane, heptane, pentane, cyclohexane, benzene and toluene can be used alone or as a polymerization solvent.

  Adjustment of MFR in these polymerizations is usually performed by introducing hydrogen. In this case, the amount of hydrogen introduced may be constant from the start to the end of the polymerization, or may be changed continuously or stepwise.

For such a first component, a random copolymerized polypropylene resin polymerized with a metallocene catalyst is used as the second component polypropylene resin.
The random copolymer polypropylene resin can be easily obtained by random copolymerization of propylene and α-olefin.
As long as this 2nd component has MFR lower than a 1st component, it can be comprised by the multiple types of random copolymer polypropylene-type resin which has the same MFR value or a different MFR value.
As the α-olefin constituting the random copolymer polypropylene resin of the second component, ethylene, butene-1, pentene-1, hexene-1, octene-1, 4-methyl-pentene-1, or the like may be used. Among them, a random copolymer with ethylene is preferable.
The addition amount of the α-olefin is usually selected from the range of 0.3 to 2.0% by weight, preferably 0.6 to 1.8% by weight as the α-olefin content in the random copolymer polypropylene resin. The

As the metallocene catalyst used for the polymerization, a catalyst comprising the following components (a) and (b) or, if necessary, in addition to (a) and (b), further obtained by combining component (c). Things can be illustrated.
Component (a): Transition metal complex compound represented by the following structural formula (I) Component (b): Promoting the component (a) by reacting with a cocatalyst, ie, component (a) Compound component (c): Organoaluminum compound

(In the structural formula (I), A and A ′ are ligands containing a conjugated five-membered ring. Q is a bridging group, preferably an alkylene group, a dialkylsilylene group, a dialkylgermylene group, or a silafluorene. M is a transition metal atom of groups 4 to 6, preferably 4 of the periodic table, more preferably zirconium or hafnium, and X and Y are sigma (σ) properties such as a halogen atom or a hydrocarbon group. A and / or A ′ may have a secondary ring other than a conjugated five-membered ring, and is preferably an azulenyl group.)

The co-catalyst of component (b) is a component that activates the transition metal complex compound, and is a compound that reacts with the auxiliary ligand of the transition metal complex compound to convert the complex into an active species having olefin polymerization ability. Yes, specifically, the following (b-1) to (b-4) may be mentioned.
(B-1) Aluminum oxy compound (b-2) An ionic compound or Lewis acid (b-3) capable of reacting with the transition metal complex compound (a) to convert the transition metal complex compound (a) into a cation ) Solid acid (b-4) ion-exchange layered silicate

(B-1) As a specific example of an aluminum oxy compound, a well-known alumoxane compound can be illustrated. More specifically, methylalumoxane, ethylalumoxane, propylalumoxane, butylalumoxane, isobutylalumoxane, methylethylalumoxane, methylbutylalumoxane, methylisobutylalumoxane and the like are exemplified.

Examples of the compound (b-2) include known boron compounds, more specifically, a reaction product of trialkylaluminum and alkylboronic acid, for example, a reaction product of 2: 1 of trimethylaluminum and methylboronic acid. And a 2: 1 reactant of triisobutylaluminum and methylboronic acid, a 1: 1: 1 reactant of trimethylaluminum, triisobutylaluminum and methylboronic acid, a 2: 1 reactant of triethylaluminum and butylboronic acid, and the like. Other examples of (b-2) include ionic compounds, and more specifically, cations such as carbonium cation and ammonium cation, and triphenylboron and tris (3,5-difluorophenyl) boron. And a complex with an organic boron compound such as tris (pentafluorophenyl) boron.

Examples of the solid acid (b-3) include alumina, silica-alumina, silica-magnesia and the like.

As the ion-exchange layered silicate of (b-4), silicates such as montmorillonite, sauconite, beidellite, nontronite, saponite, hectorite, stevensite, bentonite, teniolite, and other smectites, vermiculite, and mica A compound is used.
These silicate compounds 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 compound can be used.

Specific examples include (i) acid treatment, (b) alkali treatment, (c) salt treatment, and (d) organic matter treatment.
These treatments remove ions on the surface, exchange cations between layers, and elute cations such as Al, Fe, and Mg in the crystal structure, etc., ion complexes, molecular complexes, organic derivatives, etc. Thus, the surface area, interlayer distance, solid acidity and the like of the layered silicate compound can be changed.
These processes may be performed independently or two or more processes may be combined.

  Examples of the component (c) include organoaluminum compounds such as triethylaluminum, triisobutylaluminum, and diethylaluminum chloride.

  A detailed method for producing a metallocene catalyst comprising a combination of (a) to (c) and specific examples of each component are disclosed in, for example, JP-A-10-226712, JP-A-11-240909, and JP-A-11-240909. There are disclosures in Japanese Patent Application Laid-Open Nos. 2000-95791, 2002-12596, and 2003-292518.

As a method for preparing the metallocene catalyst, the presence of a monomer to be polymerized in the polymerization tank or outside the polymerization tank of the metallocene catalyst comprising the component (a), the component (b) and the component (c) used as necessary. It can carry out by making it contact under or absence.
Further, the catalyst may be one obtained by prepolymerization in the presence of olefin.
Examples of the olefin used for the prepolymerization include propylene, ethylene, 1-butene, 3-methylbutene-1, styrene, divinylbenzene and the like.

The polymerization method of the randomly copolymerized polypropylene using the metallocene catalyst is carried out by mixing and contacting the metallocene catalyst and the required monomer.
The amount ratio of each monomer in the reaction system does not need to be constant over time, it is convenient to supply each monomer at a constant mixing ratio, and the mixing ratio of the supplied monomers can be changed over time. Is also possible.
Also, any of the monomers can be added in portions in consideration of the copolymerization reaction ratio.

As a polymerization method, any method can be adopted as long as the catalyst component and each monomer are in efficient contact with each other.
Specifically, the slurry method using an inert solvent, the bulk method using propylene as a solvent substantially without using an inert solvent, the solution polymerization method, or the monomers are substantially gaseous without using a liquid solvent substantially. It is possible to employ a gas phase method that keeps the temperature constant.
It is also applied to continuous polymerization and batch polymerization.
In the case of slurry polymerization, a saturated aliphatic or aromatic hydrocarbon such as hexane, heptane, pentane, cyclohexane, benzene and toluene can be used alone or as a polymerization solvent.

  As polymerization conditions, the polymerization temperature is −78 to 160 ° C., preferably 0 to 150 ° C., and hydrogen can be supplementarily used as a molecular weight regulator at that time. The polymerization pressure is suitably from 0 to 9 MPaG, preferably from 0 to 6 MPaG, particularly preferably from 1 to 5 MPaG.

The crystal nucleating agent is added to improve the transparency and mechanical strength of the polypropylene resin sheet, and is in a proportion of 0.01 to 1 part by weight with respect to 100 parts by weight of the resin component. It is contained in the resin composition so that
The blending ratio of the crystal nucleating agent in this resin composition is in the above range because it is difficult to ensure the transparency of the polypropylene resin sheet at a blending amount smaller than the above range, Conversely, even if it is contained in the resin composition in an amount exceeding the above range, further improvement in the transparency of the polypropylene resin sheet cannot be expected.
From the viewpoint of imparting excellent transparency to this polypropylene resin sheet, the compounding amount of the crystal nucleating agent is any of 0.03 to 0.8 parts by weight with respect to 100 parts by weight of the resin component. It is preferable that it is in the range of 0.05 to 0.6 parts by weight.

As the crystal nucleating agent, aromatic carboxylic acid metal salts, aromatic phosphate metal salts, alditol derivatives, rosin metal salts, and the like are used.
These can be used alone or in combination.
As the aromatic carboxylic acid metal salt, aluminum pt-butylbenzoate is preferable.
Examples of the aromatic metal phosphate include 2,2′-methylenebis (4,6-di-t-butylphenyl) phosphate, 2,2′-methylenebis (4,6-di-t-butyl phosphate). Phenyl) aluminum is preferred.
As the alditol derivative, a hexitol derivative and a nonitol derivative are preferable.
For example, p-methyl-benzylidene sorbitol and p-ethyl-benzylidene sorbitol are suitable.
Among these, alditol derivatives that dissolve in the resin component are preferable.
The metal salt of rosin is preferably a sodium salt of rosin.

In the resin composition used for forming the polypropylene resin sheet of the present embodiment, in addition to the essential components composed of the resin component and the crystal nucleating agent, other additional components do not significantly impair the effects of the present invention. It can mix | blend in the range.
As an optional additional component, an antioxidant, a light stabilizer, an ultraviolet absorber, a lubricant, an antistatic agent, an antifogging agent, a neutralizing agent, a metal deactivator, which are generally used for polyolefins, Coloring agents, dispersants, peroxides, fillers, fluorescent brighteners and the like can be mentioned.

Moreover, if necessary, a small amount of resin components other than the first component and the second component can be blended as an additional component.
For example, petroleum resins, elastomers, high-density polyethylene resins, linear low-density polyethylene resins, high-pressure method low-density polyethylene resins, and the like can be appropriately used within a range of 0 to less than 5% by weight.

As a method for producing the polypropylene resin sheet of the present embodiment, an extrusion molding machine equipped with a commonly used T-die can be used. A specific example will be described with a T-type die molding machine. Resin is supplied to an extruder, heated and melt-kneaded at a temperature of 190 to 260 ° C., and then extruded into a sheet from the die lip of the T-type die. And a method of producing a take-up sheet with a take-up machine by cooling with a casting drum.
For cooling, in addition to the casting drum method, a polishing roll method, a swing roll method, a belt cast method, and the like can be used. In combination with a cooling device such as an air knife method, an electrostatic contact method, or a water cooling method. It can also be used.

In the production method for producing a polypropylene resin sheet according to this embodiment, a resin comprising a resin component containing the first component and the second component, and a resin composition containing the crystal nucleating agent. The composition is extruded by the above-described extruder, and the extruded molten sheet is cooled by the cooling device as described above, whereby the bending elastic modulus in the extrusion direction in the extrusion sheet molding and the sheet width orthogonal to the extrusion direction. A flexural modulus in the direction is 2000 MPa or more, and a highly transparent polypropylene resin sheet can be obtained.
And in the thickness of 0.1-2.0 mm suitable for manufacture of a container etc., a polypropylene resin sheet can be manufactured so that it may become the outstanding transparency calculated | required by a container etc.
In the production of a container to be described later, since thermoforming is applied to a polypropylene resin sheet, there is a possibility that a value indicating transparency such as haze changes due to a change in thickness and crystallinity.
Therefore, at least the transparency required for the container needs to be provided in the polypropylene resin sheet, and usually the polypropylene resin sheet needs to be formed so that the haze is 15% or less.

The polypropylene resin sheet has a thickness of 0.1 to 2.0 mm in that it can provide excellent transparency and strength for practical use to products such as containers formed by the polypropylene resin sheet. It is preferable that it is the range of this, and it is more preferable that it is 0.1-1.5 mm. Especially preferably, it is 0.1-1.0 mm.
The above range is suitable because the transparency of the polypropylene-based resin sheet is likely to decrease when the thickness exceeds this range, and the mechanical strength of a product formed by thermoforming may be insufficient when the thickness is less than the above range. It is for having.

In the present invention, the polypropylene resin sheet can be formed by using a multilayer extrusion molding machine capable of simultaneously extruding and molding two or more kinds of resins in addition to a single layer extrusion molding machine.
In this case, layers other than the layer formed by the resin composition (other layers) can be added within a range not impairing the effects of the present invention. Examples of the other layer include olefin resins other than the resin composition, recycled resins, gas barrier resins, and adhesive resins.

In addition, the polypropylene resin sheet of this embodiment can be used for forming products such as containers after improving physical properties by applying an antistatic agent, an antifogging agent, a lubricant, or the like to the sheet surface.
Here, sucrose fatty acid ester or polyglycerin fatty acid ester can be used as the antifogging agent, and silicon oil or amide-based lubricant can be used as the lubricant.

This polypropylene resin sheet can be secondarily processed into a product such as a container by a vacuum forming method or a vacuum / pressure forming method.
In a container (container with a lid) having a container main body in which an accommodation concave portion for accommodating an object to be accommodated and a lid body is used, the bottom surface of the container main body affects the top strength and waist strength of the container. Particularly excellent strength is required for the top surface portion of the cover or the lid, and particularly excellent transparency is required for the top surface portion of the lid that affects the display of the objects to be accommodated.
Therefore, at least one of the bottom surface portion and the top surface portion is formed by the polypropylene resin sheet of the present embodiment, and the bending elastic modulus in the extrusion direction in the extrusion sheet molding of the polypropylene resin sheet is orthogonal to the extrusion direction. And a container having excellent display performance of contained objects while having a strength to withstand practical use by being formed such that the bending elastic modulus in the sheet width direction is 2000 MPa or more and haze is 15% or less. can do.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples.

[Examples 1 and 3 to 5, Comparative Examples 1 to 4]
The resin composition having the composition shown in Table 1 was extruded into a sheet shape from a extruder having a screw diameter of 32 mm and heated to 230 ° C. with a 450 mm width T-shaped die, and cast with a casting drum (flowing cooling water at 50 ° C. inside). A polypropylene resin sheet was obtained by sandwiching and solidifying by cooling.
In addition, the polypropylene resin sheet was produced, adjusting the thickness of the sheet | seat obtained at this time to be 0.3 mm.

[Example 2]
Instead of the method of cooling by sandwiching between the casting drums, the resin composition extruded from the T-shaped die 3 by the cooling device combining the roll 1 for cooling and the endless belt 2 as shown in FIG. A polypropylene resin sheet was produced in the same manner as in Example 1 except that the polypropylene resin sheet 4 was produced by being sandwiched and cooled by the belt 2.

(Evaluation of polypropylene resin sheet)
(transparency)
As for the transparency of the polypropylene resin sheets of Examples and Comparative Examples, haze was measured according to JIS K7105. In the evaluation of transparency, a haze of 15% or less was regarded as good transparency.
The evaluation results are shown in Table 1 with “◯” for those with good transparency and “×” for those with no transparency.

(Strength)
A strip-shaped test piece having a length of 50 ± 0.2 mm and a width of 25 ± 0.2 mm was cut out from the polypropylene resin sheet to produce an evaluation test piece, and the bending strength was measured.
In addition, the test piece (test piece 1) cut out so that the extrusion direction of a polypropylene resin sheet may become the longitudinal direction of an evaluation sample, and the test cut out so that the sheet width direction orthogonal to an extrusion direction may become the longitudinal direction of an evaluation sample Bending stress was measured using two types of test pieces (test piece 2).
In the measurement, the test piece was placed on two support bases separated by a distance of 20 mm under the condition of a temperature of 20 ° C. so that the gap between the support bases was positioned at the substantially central portion in the longitudinal direction of the test piece. The test piece was placed and bent by bringing the indenter into contact with a position corresponding to the central portion of the gap in the test piece from the upper surface side.
More specifically, based on the calculation method described in JIS K7171, an indenter having a curvature radius of 5 mm at the lower end is directed downward at a speed of 100 mm / min by bringing the lower end into contact with the upper surface of the test piece. The bending stress was calculated from the load applied to the test piece when it was moved, and the bending elastic modulus was calculated from the value.
As the strength of the sheet, a sheet having a bending elastic modulus of 2000 MPa or more was determined as “good”.
The evaluation results are shown in Table 1 with “◯” indicating that the strength is good and “×” indicating that the strength is not.

(Evaluation of container)
(Formability)
The polypropylene resin sheet of each Example and Comparative Example was heated from above and below with a heater set at 250 ° C. using an indirectly heated vacuum / pressure forming machine (manufactured by Kinki Machine Co., Ltd.), and the degree of vacuum was 700 torr (mmHg) 2 was molded by a vacuum / pneumatic molding method under the condition of a compressed air pressure of 3.0 kg / cm ² .
The obtained lid mold product is visually observed, and “○” indicates that the mold shape is determined to have good reproducibility, and “×” indicates that a portion of the mold shape is not reproduced. ".
The results are shown in Table 1.

(Transparency, strength)
About the transparency and intensity | strength of a molded article, it implemented similarly to the evaluation of a polypropylene resin sheet.
That is, the transparency was determined by measuring haze according to JIS K7105, and determining that the haze was 15% or less as “◯” and the other as “x”. The results are shown in Table 1.
In addition, the strength is obtained from the lid-molded product in two types of test pieces (test piece 1 whose longitudinal direction is the extrusion direction and test piece 2 whose longitudinal direction is the sheet width direction) as shown in FIG. Then, the case where the flexural modulus was 2000 MPa or more was judged as “◯”, and the case where it was not, was judged as “x”. The results are shown in Table 1.

(Waist strength)
Under the condition of a temperature of 20 ° C., the waist strength was measured by applying a force in the direction in which the central portions of the side edges on the long side (side edge on the 169 mm length side) of the lid mold product were brought close to each other.
More specifically, as shown in FIG. 4, a jig having an upper movable protrusion and a lower fixed protrusion each having a contact width of 15 mm with respect to the lid mold product is attached to a “precision universal testing machine manufactured by Shimadzu Corporation. Attached to Autograph AG-I ”, the lid mold product is set on the jig in a state where the long side of the lid mold product is parallel to the top and bottom, and the side of the 169 mm long side Set so that the upper movable protrusion and the lower fixed protrusion are in contact with each other at the center, and move the upper movable protrusion downward (in the direction of the arrow in FIG. 4) at a speed of 100 mm / min. The lid mold product was compressed by 10 mm, and the stress at that time was measured as waist strength (N).
The container is required to have a waist strength of 2N or more in the lid-shaped molded product as shown in FIG. 2 from the viewpoint of practicality.

(Height and strength)
Under the condition of a temperature of 20 ° C., the top surface portion was pressed to apply force in the direction of compressing the lid mold product, and the top and bottom strength was measured.
More specifically, as shown in FIG. 5, a through hole was formed so that air in the space surrounded by placing the lid mold product in a face-down state could be released when the lid mold product was compressed. The lower flat plate together with the upper flat plate is mounted on “Precision Universal Testing Machine Autograph AG-I” manufactured by Shimadzu Corporation, and a lid mold product is placed on the lower flat plate, and the upper flat plate is moved downward (in the direction of the arrow in FIG. 5). ) Was moved at a speed of 100 mm / min to compress the lid mold product by 10 mm, and the stress at that time was measured as the top-to-bottom strength (N).
In addition, from the viewpoint of practicality, the lid mold product as shown in FIG. 2 is required to have a top and bottom strength of 40 N or more.

(Crystallinity)
A sample for differential scanning calorimetry (DSC) measurement was collected from the lid mold product, and the heat of fusion (ΔH, unit: J / g) was measured at a heating rate of 10 ° C./min. .
Crystallinity (%) = ΔH / ΔH _OPP × 100 (%)
(Here, ΔH _OPP is 209 J / g reported in “J. Brandup and EM Innergut: Polymer Handbook. Interscience New York (1965)” as the heat of fusion of 100% crystallinity polypropylene resin. The value of

From the above results, the polypropylene resin sheet of the present invention is a sheet having excellent moldability and having both strength and transparency, and has excellent molded product strength and transparency such as waist strength that can withstand the required practical use. It can be seen that a container having both of the above can be formed by general thermoforming.
And the container of this invention can exhibit the outstanding transparency of haze 15% or less while being able to exhibit the molded article strength which can be practically used.
On the other hand, when the ratio of the polypropylene resin used, MFR, etc. is different from the polypropylene resin sheet of the present invention, at least one of the strength, transparency and moldability deteriorates, resulting in the strength and It can be seen from the above results that it is difficult to form a container that satisfies both transparency and transparency.
For example, in Comparative Example 4, since the ratio of the random copolymer polypropylene resin is large, the flexural modulus is low in the 0.3 mm thin sheet, and the flexural modulus is also obtained in the lid-shaped molded product obtained by molding this polypropylene resin sheet. Is low, and as a result, it does not have waist strength that can be put to practical use.

The side view which shows the manufacturing method of a polypropylene resin sheet. FIG. 3 is a three-sided view showing the structure of a lid mold product used for evaluation. The top view which shows the test piece sampling method from a lid-type molded article. The side view (I) and front view (B) which show the measuring method of waist strength. The top view (I) and front view (B) which show the measuring method of top and bottom strength.

Explanation of symbols

4: Polypropylene resin sheet

Claims (3)

A polypropylene resin sheet obtained by extrusion-molding a resin composition containing 0.01 to 1 part by weight of a crystal nucleating agent with respect to 100 parts by weight of a resin component containing a polypropylene resin,
The resin component is composed of one or more polypropylene resins polymerized by a Ziegler-Natta catalyst that has an MFR value measured at a temperature of 230 ° C. and a load of 2.16 kg of 1 to 5 g / 10 minutes. The first component exceeds 60% by weight and 95% by weight or less,
Further, the resin component has a second component composed of one or more random copolymerized polypropylene resins polymerized by a metallocene catalyst and having a MFR value smaller than that of the first component polypropylene resin. % Or more and less than 40% by weight,
Moreover, the bending elastic modulus in the extrusion direction of the extruded sheet molding and the bending elastic modulus in the sheet width direction orthogonal to the extrusion direction are both 2000 MPa or more and 2400 MPa or less , and the haze is 15% or less. Characteristic polypropylene resin sheet.   The polypropylene resin sheet according to claim 1, wherein the polypropylene resin used in the first component is a polypropylene resin. A polypropylene resin container in which a polypropylene resin sheet is formed by vacuum molding or vacuum pressure forming, and at least a bottom surface portion of a container body or a top surface portion of a lid is formed of the polypropylene resin sheet,
The bottom surface portion or the top surface portion is formed by using the polypropylene resin sheet according to claim 1 or 2, and the bending elastic modulus in the extrusion direction in extrusion sheet molding of the polypropylene resin sheet. And a flexural modulus in the sheet width direction orthogonal to the extrusion direction are both 2000 MPa and 2500 MPa, and a haze is 15% or less. .

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