Polypropylene resin composition, package, and method for molding package

Abstract

To achieve both reduction of resin necessary for manufacturing a cup-shaped package and reduction of frequency of maintenance of a mold in injection molding of the package.SOLUTION: Provided is a polypropylene resin composition that includes: a propylene-ethylene random copolymer (A) having (i) a melt flow rate (MFR) of 30 to 110 g / 10 min, (ii) a flexural modulus of 1,000 to 1,500 MPa, and (iii) a Charpy impact strength at 23°C of 2.0 to 7.0 kJ / m2; and a blowing agent (B) in an amount of more than 1 pt.wt. and not more than 7 pts.wt. per 100 pts.wt. of the propylene-ethylene block copolymer (A).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a polypropylene resin composition containing a propylene-ethylene random copolymer and a foaming agent, and a package made thereof, particularly a cup-shaped package having a body and a flange, and more particularly to a cup-shaped package having a body and a flange formed by injection molding using a propylene-ethylene random copolymer and a foaming agent. [Background technology]

[0002] In the production of injection-molded packages, particularly cup-shaped packages having a body and a flange, the amount of resin required to produce the package can be reduced by thinning the body. It is known that when injection-molding cup-shaped packages having a thin body and flange, sink marks are likely to occur in the flange. To eliminate these sink marks, a high injection pressure is required. As a result, unstable pressure is applied to the mold for the body of the cup-shaped package having the body and flange, making the mold prone to deformation. This results in uneven body thickness. This poses a problem, requiring frequent mold maintenance. Patent Document 1 discloses a package having a body thickness of 0.2 to 0.35 mm and a flange thickness of 0.4 to 0.7 mm, but does not address this issue at all. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-075677 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0004] The object of the present disclosure is to achieve, when injection molding a package, particularly a cup-shaped package having a body and a flange, a reduction in the amount of resin required to manufacture the cup-shaped package having a body and a flange, a reduction in the frequency of mold maintenance, and the suppression of sink marks, particularly in the flange portion of the cup-shaped package having a body and a flange. [Means for solving the problem]

[0005] The aspects of the present disclosure are as follows. Aspect 1 is characterized in that (i) the melt flow rate (MFR) is 30 to 110 g / 10 min, (ii) a flexural modulus of 1,000 to 1,500 MPa; (iii) 23°C Charpy impact strength is 2.0 to 7.0 kJ / m 2 is a propylene-ethylene random copolymer (A); The polypropylene resin composition is characterized by containing more than 1 part by weight and not more than 7 parts by weight of a blowing agent (B) relative to 100 parts by weight of the propylene-ethylene random copolymer (A).

[0006] A second aspect is a package made of the polypropylene resin composition of the first aspect.

[0007] Aspect 3 is the packaging body of aspect 2, which is a cup-shaped packaging body having a body and a flange.

[0008] A fourth aspect is the cup-shaped package according to the third aspect, in which the thickness of the body is 0.3 to 0.7 mm, and the thickness of the flange is 1.5 to 5 times the thickness of the body.

[0009] A fifth aspect is the cup-shaped packaging body according to the third or fourth aspect, wherein the flange has a thickness of 0.5 to 3.5 mm.

[0010] A sixth aspect is the method for producing a package according to any one of the second to fifth aspects, in which the package is obtained by injection molding without pressure dwell. [Effects of the Invention]

[0011] The present disclosure has the effect of using a foaming agent to increase the formability of a polypropylene resin composition, thereby reducing the amount of resin required to manufacture the package, eliminating the need for pressure holding, and suppressing the occurrence of sink marks, particularly in the flange portion of a cup-shaped package having a body and a flange.

[0012] Injection molding using the polypropylene resin composition according to the first aspect of the present disclosure can reduce the thickness of not only general packaging but also cup-shaped packaging having a body and a flange in particular, thereby reducing the amount of resin required to manufacture the packaging, while also reducing the frequency of maintenance of the injection molding mold.

[0013] The packaging body and cup-shaped packaging body having a body and a flange according to embodiments 2 to 5 of the present disclosure can simultaneously reduce the amount of resin required for production and the frequency of mold maintenance.

[0014] The injection molding method according to the sixth embodiment of the present disclosure can achieve both a reduction in the amount of resin required and a reduction in the frequency of mold maintenance. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a side view of an example of a cup-shaped package having a body and a flange. [Figure 2] 1 is a cross-sectional view of an example of a cup-shaped package having a body and a flange. [Figure 3] 1 is a top view of an example of a cup-shaped package having a body and a flange. DETAILED DESCRIPTION OF THE INVENTION

[0016] In this disclosure, "melt flow rate (MFR)" refers to the melt flow rate measured under a load of 2.16 kg at 230°C in accordance with JIS K7210 / ISO1130. Note that hereinafter, melt flow rate may be abbreviated as MFR. In the present disclosure, "Charpy impact strength" is a value measured at 23°C in accordance with JIS K7111 / ISO179.

[0017] In the present disclosure, the "flexural modulus" is a value measured in accordance with JIS K7171 / ISO178.

[0018] In this disclosure, "holding pressure" refers to continuously applying pressure to the molten resin toward the inside of the cavity after the molten resin has been filled into the cavity of the mold to prevent the resin from flowing back.

[0019] In the present disclosure, the "flange" refers to a thick portion of the edge of the cup-shaped package, and is the portion indicated by 1 in FIGS. Furthermore, by placing food inside the cup-shaped packaging body having a body and a flange of the present disclosure and fusing the flange portion to the film, the food can be sealed inside the cup-shaped packaging body having a body and a flange, and a food product can be created with the food sealed inside.

[0020] (1) Constituents of polypropylene resin composition (1-1) Propylene-ethylene random copolymer (A) (i) Melt flow rate The melt flow rate of the propylene-ethylene random copolymer (A) is 30 to 110 g / 10 min, preferably 40 to 105 g / 10 min, and more preferably 45 to 100 g / 10 min. By setting the melt flow rate within this range, it is possible to obtain the following effects: a package, particularly a cup-shaped package having a body and a flange, with less load on the mold when molding the package, and a cup-shaped package having a body and a flange that is thin but less likely to develop sink marks in the flange and is less likely to deform.

[0021] (ii) Flexural modulus The flexural modulus of the propylene-ethylene random copolymer (A) is 1,000 to 1,500 MPa, preferably 1,050 to 1,450 MPa, and more preferably 1,100 to 1,400 MPa. By setting the flexural modulus within this range, it is possible to obtain, in molding a package, particularly a cup-shaped package having a body and a flange, a cup-shaped package that is thin but resistant to deformation and has sufficient strength.

[0022] (iii) Charpy impact strength at 23°C The Charpy impact strength of the propylene-ethylene random copolymer (A) at 23°C is 2.0 to 7.0 kJ / m 2 and preferably 2.5 to 6.5 kJ / m 2 , and more preferably 3.0 to 6.0 kJ / m 2 By setting the Charpy impact strength within this range, it is possible to obtain an effect that, in molding a package, particularly a cup-shaped package having a body and a flange, the container is less likely to break and has sufficient strength, and that the cup-shaped package has a body and a flange.

[0023] (iv) Ethylene content The ethylene content of the propylene-ethylene random copolymer (A) is usually 1 to 5% by weight (where the total of propylene and ethylene in the propylene-ethylene random copolymer (A) is 100% by weight), preferably 1.2 to 4.6% by weight, more preferably 1.5 to 4.3% by weight, and even more preferably 1.8 to 4.0% by weight. By setting the ethylene content within the above range, it becomes easy to set various mechanical properties of the polypropylene resin composition of the present invention within desired ranges, and at the same time, it becomes easy to achieve both strength and weight reduction while preventing sink marks on the flange in a packaging product molded using the polypropylene resin composition of the present invention, particularly a cup-shaped packaging product having a body and a flange.

[0024] (1-2) Preparation of Propylene-Ethylene Random Copolymer (A) The method for producing the propylene-ethylene random copolymer (A) used in the present disclosure is not particularly limited, and it can be produced, for example, using a conventionally known production method. In order to obtain the properties of the propylene-ethylene random copolymer (A) used in the present invention, a polymerization method using a stereoregular catalyst is preferred. Examples of the stereoregular catalyst include Ziegler catalysts and metallocene catalysts.

[0025] (1-2-1) Catalyst Examples of Ziegler catalysts include two-component catalysts consisting of a transition metal component, such as a titanium halide compound such as titanium trichloride, titanium tetrachloride, or trichloroethoxytitanium, or a contact product of the titanium halide compound with a magnesium compound, typically a magnesium halide, and an organometallic component, such as an alkylaluminum compound or its halide, hydride, or alkoxide, and further three-component catalysts in which an electron-donating compound containing nitrogen, carbon, phosphorus, sulfur, oxygen, silicon, or the like is added to any of the above components.

[0026] The metallocene catalyst is preferably a supported type. A particularly preferred example of the supported metallocene catalyst is an ion-exchanged layered silicate in which the support also functions as a co-catalyst, which is obtained by combining the following components [A], [B], and, if necessary, the component [C].

[0027] Component [A] Metallocene complex Transition metal compounds of groups 4-6 of the periodic table containing at least one conjugated five-membered ring ligand ·Component [B] Promoter Ion-exchange layered silicate Component [C] Organoaluminum compound

[0028] Component [A] Metallocene complex Specifically, the compound represented by the following formula [I] can be used as the component [A]. Q(C5H 4-a R1a )(C5H 4-b R 2b )MXY ···[I] In formula [I], Q represents a linking group that bridges two conjugated five-membered ring ligands. M represents a transition metal of Groups 4 to 6 of the periodic table, and among these, titanium, zirconium and hafnium are preferred. X and Y each independently represent hydrogen, halogen, a hydrocarbon group having 1 to 20 carbon atoms, an oxygen-containing hydrocarbon group having 1 to 20 carbon atoms, a nitrogen-containing hydrocarbon group having 1 to 20 carbon atoms, a phosphorus-containing hydrocarbon group having 1 to 20 carbon atoms, or a silicon-containing hydrocarbon group having 1 to 20 carbon atoms.

[0029] R1 and R2 each independently represent a hydrocarbon group having 1 to 20 carbon atoms, a halogen, a halogen-containing hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group, an aryloxy group, a silicon-containing hydrocarbon group, a phosphorus-containing hydrocarbon group, a nitrogen-containing hydrocarbon group, or a boron-containing hydrocarbon group. Two adjacent R1s or two adjacent R2s may be bonded to form a C4 to C10 ring. In particular, it is preferable that they form a 6-membered ring or a 7-membered ring, which, together with the above-mentioned conjugated five-membered ring, form an indene ring or an azulene ring. a and b are integers satisfying 0≦a≦4 and 0≦b≦4. Examples of the bonding group Q that bridges two conjugated five-membered ring ligands include an alkylene group, an alkylidene group, a silylene group, and a germylene group. These may have hydrogen atoms substituted with alkyl groups, halogens, etc. A silylene group is particularly preferred.

[0030] Specific preferred examples of the metallocene complex include the following compounds: (1) Methylenebis(cyclopentadienyl)zirconium dichloride (2) Methylene(cyclopentadienyl)(3,4-dimethylcyclopentadienyl)zirconium dichloride (3) Isopropylidene(cyclopentadienyl)(3,4-dimethylcyclopentadienyl)zirconium dichloride (4) Ethylene(cyclopentadienyl)(3,5-dimethylpentadienyl)zirconium dichloride (5) Methylenebis(indenyl)zirconium dichloride (6) Ethylenebis(2-methylindenyl)zirconium dichloride (7) Ethylene 1,2-bis(4-phenylindenyl)zirconium dichloride (8) Ethylene(cyclopentadienyl)(fluorenyl)zirconium dichloride

[0031] (9) Dimethylsilylene(cyclopentadienyl)(tetramethylcyclopentadienyl)zirconium dichloride (10) Dimethylsilylenebis(indenyl)zirconium dichloride (11) Dimethylsilylenebis(4,5,6,7-tetrahydroindenyl)zirconium dichloride (12) Dimethylsilylene(cyclopentadienyl)(fluorenyl)zirconium dichloride (13) Dimethylsilylene(cyclopentadienyl)(octahydrofluorenyl)zirconium dichloride (14) Methylphenylsilylenebis[1-(2-methyl-4,5-benzo(indenyl)]zirconium dichloride (15) Dimethylsilylenebis[1-(2-methyl-4,5-benzoindenyl)]zirconium dichloride (16) Dimethylsilylenebis[1-(2-methyl-4H-azulenyl)]zirconium dichloride (17) Dimethylsilylenebis[1-(2-methyl-4-(4-chlorophenyl)-4H-azulenyl)]zirconium dichloride (18) Dimethylsilylenebis[1-(2-ethyl-4-(4-chlorophenyl)-4H-azulenyl)]zirconium dichloride (19) Dimethylsilylenebis[1-(2-ethyl-4-naphthyl-4H-azulenyl)]zirconium dichloride

[0032] (20) Diphenylsilylenebis[1-(2-methyl-4-(4-chlorophenyl)-4H-azulenyl)]zirconium dichloride (21) Dimethylsilylenebis[1-(2-methyl-4-(phenylindenyl))]zirconium dichloride (22) Dimethylsilylenebis[1-(2-ethyl-4-(phenylindenyl))]zirconium dichloride (23) Dimethylsilylenebis[1-(2-ethyl-4-naphthyl-4H-azulenyl)]zirconium dichloride (24) Dimethylgermylenebis(indenyl)zirconium dichloride (25) Dimethylgermylene(cyclopentadienyl)(fluorenyl)zirconium dichloride In addition, the same compounds as those mentioned above are also preferred as other Group 4, 5, and 6 transition metal compounds, such as titanium compounds and hafnium compounds. These compounds may be used in combination with the catalyst component and catalyst of the present disclosure.

[0033] Component [B] Co-catalyst (ion-exchange layered silicate) The ion-exchangeable layered silicate is not limited to a naturally occurring one, but may also be an artificially synthesized product. Clay compounds can be used as the ion-exchangeable layered silicate, and specific examples of clay compounds include the following layered silicates described in "Clay Mineralogy" by Haruo Shiramizu, Asakura Shoten (1995). (A) Kaolin group, such as dickite, nacrite, kaolinite, anoxite, metahalloysite, and halloysite, whose main constituent layers are 1:1 type structures; serpentine group, such as chrysotile, lisardite, and antigorite (a) Smectite group such as montmorillonite, sauconite, beidellite, nontronite, saponite, hectorite, stevensite, etc., vermiculite group such as vermiculite, mica group such as mica, illite, sericite, glauconite, attapulgite, sepiolite, palygorskite, bentonite, pyrophyllite, talc, chlorite group, which have a 2:1 type structure as their main constituent layer.

[0034] The silicate used in the present disclosure may be a layered silicate in which the above-mentioned (a) and (b) mixed layers are formed. In the present disclosure, the silicate as the main component is preferably a silicate having a 2:1 type structure, more preferably a smectite group silicate, and particularly preferably montmorillonite.

[0035] The activity of these silicates can be improved by chemically treating them with an acid, a salt, an alkali, an oxidizing agent, a reducing agent, an organic solvent, or the like. The acid treatment removes impurities on the surface of the ion-exchange layered silicate particles, exchanges interlayer cations, and also dissolves some or all of the cations such as Al, Fe, and Mg in the crystal structure. The acid used in the acid treatment includes hydrochloric acid, nitric acid, sulfuric acid, etc., but inorganic acids are preferred, and sulfuric acid is particularly preferred. There are no particular restrictions on the conditions for the acid treatment, but the preferred conditions are a 5 to 50 wt % aqueous acid solution reacted at a temperature of 60 to 100°C for 1 to 24 hours, with the acid concentration being variable during this time. After the acid treatment, washing is usually carried out. Washing is an operation for separating and removing the acid contained in the treatment system from the ion-exchange layered silicate.

[0036] The salts used in the salt treatment are preferably selected to contain specific cations, preferably monovalent to tetravalent metal cations, and more preferably Li, Ni, Zn, or Hf cations. Specific examples of salts include the following: Examples of those with a Li cation include LiCl, LiBr, Li2SO4, Li3(PO4), Li(ClO4), Li2(C2O4), LiNO3, Li(OOCCH3), and Li2(C4H4O4). Examples of those with a Ni cation include NiCO3, Ni(NO3)2, NiC2O4, Ni(ClO4)2, NiSO4, NiCl2, and NiBr2. Examples of compounds with a Zn cation include Zn(OOCH3)2, Zn(CH3COCHCOCH3)2, ZnCO3, Zn(NO3)2, Zn(ClO4)2, Zn3(PO4)2, ZnSO4, ZnF2, ZnCl2, ZnBr2, and ZnI2. Examples of compounds with a cation of Hf include Hf(OOCCH3)4, Hf(CO3)2, Hf(NO3)4, Hf(SO4)2, HfOCl2, HfF4, HfCl4, HfBr4, and HfI4.

[0037] After the chemical treatment, drying is carried out. Generally, drying can be carried out at a temperature of 100 to 800°C, and high temperature conditions that cause structural destruction (for example, 800°C or higher, although this depends on the heating time) are not preferred. Even if the structure is not destroyed, the properties change depending on the drying temperature, so it is preferable to change the drying temperature depending on the application. The drying time is usually 1 minute to 24 hours, preferably 5 minutes to 4 hours, and the atmosphere is dry air, dry nitrogen, dry argon, or under reduced pressure. There are no particular limitations on the drying method, and various methods can be used.

[0038] Component [C] Organoaluminum compound The organoaluminum compound of component [C] is a component that is optionally used as needed, and is most preferably a compound represented by the following formula [II]: (AlR4 p X 3-p ) q [II] In formula [II], R4 represents a hydrocarbon group having 1 to 20 carbon atoms, X represents a halogen atom, a hydrogen atom, an alkoxy group, or an amino group, p represents an integer of 1 to 3, and q represents an integer of 1 to 2. R4 is preferably an alkyl group, and when X is an alkoxy group, it is preferably an alkoxy group having 1 to 8 carbon atoms, and when X is an amino group, it is preferably an amino group having 1 to 8 carbon atoms. Of these, preferred are trialkylaluminums where p = 3 and q = 1 and dialkylaluminum hydrides where p = 2 and q = 1. More preferred are trialkylaluminums where R4 has 1 to 8 carbon atoms.

[0039] The organoaluminum compounds can be used alone or in combination, and can be added not only during catalyst preparation but also during prepolymerization or main polymerization.

[0040] (1-2-2) Method for producing propylene-ethylene random copolymer (A) The method for producing the propylene-ethylene random copolymer (A) is not particularly limited, but a polymerization method using the above-mentioned stereoregular catalyst is preferred. Examples of the stereoregular catalyst include a Ziegler catalyst and a metallocene catalyst. The Ziegler-based propylene-ethylene random copolymer (A) can be produced by copolymerizing propylene and ethylene using a Ziegler catalyst. The metallocene-based propylene-ethylene random copolymer (A) can be produced by copolymerizing propylene and ethylene using a metallocene catalyst.

[0041] Examples of methods for producing the propylene-ethylene random copolymer (A) include polymerization methods such as slurry polymerization using an inert solvent in the presence of the above catalyst, solution polymerization, gas phase polymerization using substantially no solvent, and bulk polymerization using the polymerization monomer as the solvent. For example, in the case of a slurry polymerization method, the polymerization can be carried out in an inert hydrocarbon such as n-butane, isobutane, n-pentane, isopentane, hexane, heptane, octane, cyclohexane, benzene, toluene, or xylene. In the case of a bulk polymerization method, the polymerization can be carried out in a liquid polymerization monomer. The polymerization temperature is usually -80 to 150°C, preferably 40 to 120°C. The polymerization pressure is preferably 1 to 60 atmospheres (0.10 to 6.08 MPa), and the molecular weight of the resulting propylene polymer (a) can be adjusted with hydrogen or other known molecular weight modifiers. The polymerization can be carried out by a continuous or batch reaction under conditions commonly used. Furthermore, the polymerization reaction can be carried out in one stage or multiple stages. When a metallocene catalyst is used, it is desirable to carry out a prepolymerization treatment before the main polymerization. The monomers to be subjected to the prepolymerization may be α-olefins such as ethylene, propylene, 1-butene, and 1-hexene, diene compounds such as 1,3-butadiene, and vinyl compounds such as styrene and divinylbenzene. This prepolymerization is preferably carried out in an inert solvent under mild conditions, and is desirably carried out so that 0.01 to 1,000 g, preferably 0.1 to 100 g, of polymer is produced per 1 g of solid catalyst (total of component [A] and component [B]).

[0042] The polymerization reaction is carried out in the presence or absence of a solvent such as an inert hydrocarbon such as butane, pentane, hexane, heptane, toluene, or cyclohexane, or a liquefied α-olefin. In the present invention, it is desirable to maximize the amount of polymer produced per solid catalyst (if the solid catalyst has been prepolymerized, this does not include the polymer produced by the prepolymerization). In order to increase the amount of polymer produced, it is desirable to set both the polymerization temperature and polymerization pressure relatively high.

[0043] Typically, the polymerization temperature is selected from 60 to 90°C, and the polymerization pressure is selected from about 1.5 to 4 MPa. In particular, in the case of bulk polymerization, the polymerization temperature is preferably 60 to 80°C, and the polymerization pressure is preferably selected from about 2.5 to 4 MPa in correlation with the temperature. On the other hand, in the case of gas-phase polymerization, the polymerization temperature is preferably 70 to 90°C, and the polymerization pressure is preferably selected from about 1.5 to 4 MPa. Furthermore, the polymer production amount per solid catalyst can be increased by increasing the residence time of the solid catalyst, but if it is too long, productivity will be affected. The preferred residence time is 1 to 8 hours, more preferably 1 to 6 hours. It is desirable to set the polymerization conditions so that the polymer production amount per 1 g of solid catalyst including the carrier is 20 kg or more, preferably 25 kg or more, more preferably 30 kg or more. Hydrogen may be present in the polymerization system as a molecular weight modifier. Furthermore, the polymerization may be carried out in multiple stages by changing the polymerization temperature, the concentration of the molecular weight modifier, etc.

[0044] Such propylene-ethylene random copolymers are commercially available in various forms from various companies, such as the Novatec series manufactured by Japan Polypropylene Corporation, and a desired product may be selected from these and used as the propylene-ethylene random copolymer (A).

[0045] (2) Foaming agent (B) The foaming agent (B) used in the present disclosure is a chemical foaming agent, a physical foaming agent, a microcapsule, or the like, and has the function of increasing the foaming ratio and exhibiting a good surface appearance in the polypropylene resin composition, its packaging, and a cup-shaped packaging having a body and a flange (hereinafter, collectively referred to as "foamed molded article").

[0046] (2-1) Types, functions, etc. The type of foaming agent (B) includes, for example, chemical foaming agents, physical foaming agents, and microcapsules, and any foaming agent that can be normally used in foam molding can be used without any particular limitation. Examples of chemical foaming agents include inorganic chemical foaming agents such as sodium bicarbonate, sodium carbonate, ammonium bicarbonate, ammonium carbonate, and ammonium nitrite, and organic chemical foaming agents such as azodicarbonamide (ADCA), N,N'-dinitrosopentamethylenetetramine, benzenesulfonyl hydrazide, and 4,4'-diphenyldisulfonyl azide.

[0047] In order to stably produce uniformly fine bubbles in the foamed molded article, organic acids such as citric acid and organic acid metal salts such as sodium citrate that promote gas generation can be used or added in combination with these chemical foaming agents, as needed. In addition, inorganic fine particles such as talc and lithium carbonate can also be added as nucleating agents.

[0048] As a chemical foaming agent, various molding machines such as a normal injection molding machine can be used. As described above, various chemical foaming agents are available, such as inorganic and organic ones, and preferred ones include sodium bicarbonate, citric acid, sodium citrate, and mixtures of two or more of these, and more preferred ones include sodium bicarbonate, a combination of sodium bicarbonate and sodium citrate, and a combination of sodium bicarbonate and citric acid. Inorganic ones are preferred because they are more likely to produce uniform, fine bubbles in the molded product.

[0049] These chemical foaming agents are processed into particles having an average particle size of 1 to 100 μm, and then kneaded with component A or sprinkled on granulated material of component A during foam molding. These particles are then supplied to various molding machines, such as injection molding machines, or injected into the middle of the cylinder of the injection molding machine during injection molding, where they decompose inside the cylinder and generate gas such as carbon dioxide. Furthermore, in terms of ease of handling, storage stability, dispersibility in the above-mentioned component A, etc., the chemical foaming agent can also be used after granulating it as a masterbatch using a polyolefin resin as a base material. This can prevent contamination of the molding machine hopper and adhesion of powder to the surface of the molded product. In this case, it is usually preferable to use it as a masterbatch of a polyolefin resin with a concentration of 10 to 50% by weight. Alternatively, a chemical foaming agent may be added once and then decomposed by pelletization, or a high concentration of the chemical foaming agent may be decomposed in advance and the resulting residue may be added. The chemical foaming agent decomposes in the cylinder of the molding machine, and the resulting foaming residue can serve as a foam nucleating agent.

[0050] Examples of physical foaming agents include inert gases, vapors of low-boiling organic solvents, vapors of halogen-based inert solvents, and air. Examples of inert gases include carbon dioxide, nitrogen, argon, helium, neon, astatine, etc. Examples of vapors of low-boiling organic solvents include methanol, ethanol, propane, butane, pentane, etc. Examples of vapors of halogen-based inert solvents include dichloromethane, chloroform, carbon tetrachloride, chlorofluorocarbons, nitrogen trifluoride, etc. Among these, it is preferable to use inert gases, since they do not need to be converted into vapor, are inexpensive, and pose very little risk of environmental pollution and fire. In particular, carbon dioxide and nitrogen are preferred. Argon and helium are preferred, and carbon dioxide and nitrogen are more preferred. Furthermore, the physical foaming agent is preferably in a supercritical state, which has the advantage of facilitating gas dissolution into the resin. The physical foaming agent is kneaded with the propylene-ethylene random copolymer (A) in the cylinder of various molding machines, such as an injection molding machine, or is injected as a gaseous or supercritical fluid into granules of the propylene-ethylene random copolymer (A), and dispersed or dissolved therein. After injection into a mold, the physical foaming agent functions as a foaming agent when the pressure is released.

[0051] Microcapsules contain a blowing agent (expansion agent) within a shell made of various thermoplastic resins. Examples of blowing agents (expansion agents) include specific Freons such as trichlorofluoromethane, dichlorofluoromethane, and dichlorofluoroethane, alternative Freons, hydrocarbons such as n-pentane, isopentane, isobutane, and petroleum ether, and chlorinated hydrocarbons such as methyl chloride, methylene chloride, and dichloroethylene. The average particle size of the microcapsule-shaped blowing agent is usually 2 to 50 μm. These microcapsules are usually kneaded with the propylene-ethylene random copolymer (A) or pre-mixed with a granulated product of the propylene-ethylene random copolymer (A), and then supplied to various molding machines such as injection molding machines for use.

[0052] In order to improve the surface appearance of the polypropylene resin composition and the molded article thereof by foaming and to further increase the expansion ratio, it is preferable to use a chemical foaming agent and a physical foaming agent in combination as the foaming agent (B), and it is more preferable to use an inorganic chemical foaming agent in combination with carbon dioxide gas or nitrogen as a physical foaming agent.

[0053] (2-2) Blend ratio The proportion of the blowing agent (B) in the polypropylene resin composition of the present disclosure is more than 1 part by weight and not more than 7 parts by weight, preferably 2 to 6 parts by weight, and more preferably 3 to 5 parts by weight, per 100 parts by weight of the propylene-ethylene random copolymer (A). In this case, the blending ratio refers to the actual concentration of the blowing agent. For example, when a masterbatch of blowing agent (B) and a polyolefin resin is used, it is calculated based on the concentration of the blowing agent contained in the masterbatch. By setting the blowing agent (B) content within the range specified in the present application, the polypropylene resin composition is sufficiently foamed during molding, and the molded article after foaming has sufficient mechanical strength, such as impact strength, while secondary foaming can be suppressed. That is, if the blending ratio of blowing agent (B) is 1 part by weight or less, the polypropylene resin composition does not foam sufficiently. On the other hand, if the blending ratio exceeds 7 parts by weight, the mechanical strength, such as impact strength, of the molded article after foaming of the polypropylene resin composition decreases, secondary foaming (a phenomenon in which the surface of the foamed molded article blister-like swelling occurs due to excess remaining foaming gas), and further, it is economically disadvantageous.

[0054] When a physical foaming agent is used, the amount of gas injected can be appropriately set by, for example, adjusting the injection pressure of the gas used. If the gas injection pressure is insufficient or excessive, the polypropylene resin composition will not foam sufficiently, and the mechanical strength of the foamed molded article will decrease, as in the case of the above-mentioned chemical foaming agent. Two or more types of foaming agent (B) can also be used in combination.

[0055] (3) Other additives In the polypropylene resin composition according to the present disclosure, in addition to the propylene-ethylene random copolymer (A) and the blowing agent (B), other additive components may be blended, if necessary, in an amount of about 0.01 to 5 parts by weight per 100 parts by weight of the propylene-ethylene random copolymer (A), to further improve the effects of the present disclosure or to impart other effects, within a range that does not impair the effects of the present disclosure. The optimal blending amount may be selected depending on the properties of each blended substance.

[0056] Specific examples of such additives include hindered amine-based light stabilizers, benzotriazole-based ultraviolet absorbers, sorbitol-based nucleating agents, pigments and other colorants, phenolic and phosphorus-based antioxidants, nonionic antistatic agents, inorganic compound neutralizing agents, thiazole-based antibacterial and antifungal agents, halogenated compound flame retardants, process oil (compounded oil), plasticizers, organic metal salt-based dispersants, fatty acid amide-based lubricants, nitrogen compound metal deactivators, nonionic surfactants, polyolefins other than component A, such as polypropylene, thermoplastic resins such as polyamide and polyester, and fillers. These may be used in combination of two or more kinds, may be added to the composition, or may be added to, for example, the propylene-ethylene random copolymer (A) or a masterbatch of the blowing agent (B), or two or more kinds of each component may also be used in combination.

[0057] Light stabilizers and ultraviolet absorbers, such as hindered amine compounds, benzotriazoles, benzophenones and salicylates, are effective in imparting or improving the weather resistance and durability of polypropylene resin compositions and foam-molded articles thereof. Specific examples of the hindered amine compound include a condensation product of dimethyl succinate and 1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine; poly[[6-(1,1,3,3-tetramethylbutyl)imino-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidyl)imino]hexamethylene[(2,2,6,6-tetramethyl-4-piperidyl)imino]]; tetrakis(2,2,6,6-tetramethyl-4-piperidyl)1,2,3,4-butanetetracarboxylate; tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)1,2,3,4-butanetetracarboxylate; bis(1,2,2,6,6-pentamethyi) bis-2,2,6,6-tetramethyl-4-piperidyl sebacate; bis-2,2,6,6-tetramethyl-4-piperidyl sebacate; benzotriazoles include 2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzotriazole; 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole; benzophenones include 2-hydroxy-4-methoxybenzophenone; 2-hydroxy-4-n-octoxybenzophenone; and salicylate compounds include 4-t-butylphenyl salicylate; 2,4-di-t-butylphenyl 3',5'-di-t-butyl-4'-hydroxybenzoate.

[0058] Nucleating agents such as inorganic, sorbitol, metal carboxylate, and organic phosphate nucleating agents are effective in imparting or improving the rigidity, heat resistance, hardness, and foam moldability of polypropylene resin compositions and foam-molded articles thereof. Specific examples of inorganic compounds include talc and silica, and sorbitol compounds include 1,3,2,4-dibenzylidene-sorbitol; 1,3,2,4-di-(p-methyl-benzylidene)sorbitol; 1,3,2,4-di-(p-ethyl-benzylidene)sorbitol; 1,3,2,4-di-(2',4'-di-methyl-benzylidene)sorbitol; 1,3-p-chlorobenzylidene-2,4-p-methyl-benzylidene-sorbitol; 1,3,2,4-di-(p-propylbenzyl) Examples of metal carboxylates include aluminum mono-hydroxy-di-pt-butylbenzoate, sodium benzoate, and calcium montanate. Examples of organic phosphates include sodium bis(4-t-butylphenyl)phosphate, sodium 2,2'-methylene-bis(4,6-di-t-butylphenyl)phosphate, and lithium 2,2'-methylene-bis(4,6-di-t-butylphenyl)phosphate.

[0059] Furthermore, colorants such as inorganic or organic pigments are effective in imparting or improving the colored appearance, appearance, texture, commercial value, weather resistance, durability, etc. of polypropylene resin compositions and foam-molded articles thereof. Specific examples of inorganic pigments include titanium oxide, iron oxide (such as red iron oxide), chromic acid (such as lead chrome), molybdic acid, selenide sulfide, ferrocyanide, and carbon black. Specific examples of organic pigments include azo pigments such as sparingly soluble azo lakes, soluble azo lakes, insoluble azo chelates, condensed azo chelates, and other azo chelates; phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green; anthraquinone, perinone, perylene, and threne pigments such as thioindigo; dye lakes; quinacridones; dioxazines; and isoindolinones. To achieve metallic or pearlescent finishes, aluminum flakes and pearlescent pigments can be added. Dyes can also be added.

[0060] Furthermore, antioxidants such as phenol-based, phosphorus-based and sulfur-based antioxidants are effective in imparting or improving the heat resistance, processing stability and heat aging resistance of the polypropylene resin composition and its foamed molded article. Examples of phenolic antioxidants include 2,6-di-t-butyl-4-methylphenol; tetrakis[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]-methane; and tris(3,5-di-t-butyl-4-hydroxyphenyl)isocyanurate. Examples of phosphorus-based antioxidants include distearyl pentaerythritol diphosphite; tris(2,4-di-t-butylphenyl)phosphite; and tris(2-t-butyl-4-methylphenyl)phosphite. Examples of sulfur-based antioxidants include distearyl thiodipropionate.

[0061] Furthermore, as an antistatic agent, for example, a nonionic or cationic antistatic agent is effective in imparting or improving the antistatic properties of the polypropylene resin composition and its foam-molded article. Specific examples include polyoxyethylene alkylamines; polyoxyethylene alkylamides; polyoxyethylene alkylphenyl ethers; stearic acid monoglycerides; alkyldiethanolamines; alkyldiethanolamides; alkyldiethanolamine fatty acid monoesters; and tetraalkylammonium salts.

[0062] (4) Method for producing polypropylene resin composition Examples of methods for producing the polypropylene resin composition according to the present disclosure include a method of mixing the propylene-ethylene random copolymer (A) and the blowing agent (B), optionally further adding any of the other additive components, and dry blending the mixture by sprinkling or hand blending; a method of mixing the mixture using various blenders, mixers, etc., such as a V-blender or a tumbler mixer; a method of melting, kneading, and granulating the mixture using a conventional kneader, such as a single-screw extruder, a twin-screw extruder, a Banbury mixer, a roll mixer, a Brabender plastograph, or a kneader; and a method of directly feeding the components separately (or partially blended) into various molding machines, such as an injection molding machine.

[0063] When the melt-kneading-granulation method is selected, it is usually preferable to use a twin-screw extruder for melt-kneading and granulation. During this melt-kneading-granulation, the blend of the propylene-ethylene random copolymer (A) and the blowing agent (B) (and optionally the optional other additive components) may be melt-kneaded and granulated simultaneously. Alternatively, to improve performance, the components may be separated; for example, first, the propylene-ethylene random copolymer (A) and a portion of the blowing agent (B) are melt-kneaded and granulated, and then the remaining components are melt-kneaded and granulated. Furthermore, when all or a portion of the blowing agent (B) is melt-kneaded and granulated during the foam molding stage, only the components excluding all or a portion of the blowing agent (B) are melt-kneaded and granulated.

[0064] In the production of the polypropylene resin composition according to the present disclosure, a molecular weight lowering agent can be blended and mixed, melted, kneaded, and granulated to improve the fluidity, foam moldability, surface appearance, and expansion ratio of the resin composition. That is, when the blend of the propylene-ethylene random copolymer (A) and the blowing agent (B) is mixed, melted, kneaded, and granulated, an appropriate amount of the molecular weight lowering agent is simultaneously blended, mixed, melted, kneaded, and granulated. In this case, the polypropylene resin composition can also be produced by blending alone. Here, the molecular weight of the propylene-ethylene random copolymer (A) can be lowered in advance by blending the molecular weight lowering agent only with the propylene-ethylene random copolymer (A) and then mixing, melting, kneading, and granulating the resulting copolymer. This molecular weight-lowered propylene-ethylene random copolymer (A) can then be mixed, melted, kneaded, and granulated simultaneously with other blending components such as the blowing agent (B). In addition, an appropriate amount of a molecular weight lowering agent can be added directly to the blend of the propylene-ethylene random copolymer (A) and the blowing agent (B) into various molding machines such as an injection molding machine, either simultaneously or individually, and then molded.

[0065] As the molecular weight lowering agent, various organic peroxides and so-called decomposition (oxidation) accelerators can be used, with organic peroxides being preferred. Examples of organic peroxides that can be used as molecular weight reducers include benzoyl peroxide, t-butyl perbenzoate, t-butyl peracetate, t-butylperoxyisopropyl carbonate, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, 2,5-dimethyl-2,5-di(benzoylperoxy)hexyne-3, t-butyl-diperadipate, t-butylperoxy-3,5,5-trimethylhexanoate, methyl ethyl ketone peroxide, cyclohexanone peroxide, di-t-butyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, and 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3. Examples of the peroxyhydroxide include, but are not limited to, one or more selected from the group consisting of 1,3-bis-(t-butylperoxyisopropyl)benzene, t-butylcumyl peroxide, 1,1-bis-(t-butylperoxy)-3,3,5-trimethylcyclohexane, 1,1-bis-(t-butylperoxy)cyclohexane, 2,2-bis-t-butylperoxybutane, p-menthane hydroperoxide, di-isopropylbenzene hydroperoxide, cumene hydroperoxide, t-butyl hydroperoxide, p-cymene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, and 2,5-dimethyl-2,5-di-(hydroperoxy)hexane.

[0066] In the present disclosure, the amount of the molecular weight lowering agent is not particularly limited, but is usually about 0.005 to 0.5 parts by weight per 100 parts by weight of the propylene-ethylene random copolymer (A). If the amount of the molecular weight lowering agent is less than 0.005 part by weight, the molecular weight lowering effect is poor, and if it exceeds 0.5 part by weight, the surface appearance of the foamed molded article may deteriorate.

[0067] (5) Package and cup-shaped package (foam molded product) having a body and a flange, and its manufacturing method and use The packaging of the present invention, particularly the cup-shaped packaging having a body and a flange, is prevented from deformation of the body or flange and from sinking in the flange. Therefore, by placing food inside the cup-shaped packaging having a body and a flange of the present disclosure and fusing the flange portion to the film, the food can be sealed inside the cup-shaped packaging having a body and a flange, and a food product can be created with the food sealed inside.

[0068] The thickness of the body of the cup-shaped packaging having a body and a flange is preferably 0.3 to 0.7 mm, more preferably 0.35 to 0.6 mm, and even more preferably 0.4 to 0.5 mm. By setting the thickness of the body of the cup-shaped packaging having a body and a flange within this range, the amount of resin required for manufacturing the cup-shaped packaging having a body and a flange can be reduced, and deformation of the body can be prevented even though the cup-shaped packaging having a body and a flange is thin and lightweight. The thickness of the flange of a cup-shaped packaging body having a body and a flange is preferably 1.5 to 5 times the thickness of the body, more preferably 1.6 to 4.5 times, and particularly preferably 1.7 to 4 times. By setting the thickness of the flange of a cup-shaped packaging body having a body and a flange within this range, it is possible to prevent deformation of the cup-shaped packaging body having a body and a flange and to achieve easy opening when the flange portion is fused to the film, despite the fact that the cup-shaped molding having a body and a flange is thin and lightweight. The thickness of the flange is preferably 0.5 to 3.5 mm, more preferably 0.6 to 2.5 mm, and particularly preferably 0.7 to 1.5 mm. By setting the thickness of the flange within this range, it is possible to prevent deformation of the cup-shaped package having a body and a flange and to make it easy to open, despite the fact that the cup-shaped molded product is thin and lightweight and has a body and a flange. In the method for producing the packaging body of the present invention, it is preferable to carry out injection molding without holding pressure when obtaining the packaging body. If pressure holding is performed during injection molding, a predetermined pressure is maintained after injection molding, and the predetermined pressure continues to be applied to the mold, increasing the risk of the mold being significantly deformed. By performing injection molding without pressure holding, the pressure applied to the mold after injection molding is reduced compared to when pressure holding is performed, and the time that pressure is applied to the mold is shortened, making it possible to prevent mold deformation and improve operability by reducing the number of maintenance times. By performing injection molding without pressure holding, the pressure on the mold can be reduced, deformation can be reduced, and the mold can be more easily maintained. [Example]

[0069] The present disclosure will be described in detail below with reference to examples and comparative examples, but the present disclosure is not limited to these examples.

[0070] (1) Evaluation method (1-1) Melt flow rate (MFR) The melt flow rate was measured in accordance with JIS K7210 / ISO1130, with a load of 2.16 kg and a resin temperature of 230°C.

[0071] (1-2) Flexural modulus The flexural modulus was measured in accordance with JIS K7171 / ISO178.

[0072] (1-3) Charpy impact strength The Charpy impact strength was measured at 23°C in accordance with JIS K7111 / ISO179.

[0073] (1-4) Ethylene content 13 The ethylene-propylene random copolymer whose composition was verified by C-NMR was used as the standard substance. -1The ethylene content in the random copolymer was measured by infrared spectroscopy using the characteristic absorption band of (a calibration curve was prepared). Based on the prepared calibration curve, a propylene-based polymer sample was press-molded into a film of approximately 500 μm thickness, and the ethylene content was measured by infrared spectroscopy. Here, the propylene and ethylene contents of the reference materials for creating the calibration curve are as follows: 13 The value was measured by C-NMR. 13 The C-NMR spectrum was analyzed according to the analytical method described in JP-A-2006-307120, and the contents of propylene and ethylene were calculated. Equipment: JEOL-GSX270 manufactured by JEOL Ltd. Concentration: 300mg / 2mL Solvent: orthodichlorobenzene

[0074] (1-5) Flange appearance When the appearance of the cup-shaped packaging body having a body and a flange was visually inspected, if there were no sink marks on the flange of the cup-shaped packaging body having a body and a flange and the entire flange was flat, the "appearance" was evaluated as "○", and otherwise it was evaluated as "×".

[0075] (1-6) Weight Eight cup-shaped packages each having a body and a flange were stacked, and their weights were measured using a precision balance. The weight thus obtained was then divided by 8 to determine the weight per cup-shaped package having a body and a flange. The unit of "weight" is g. Using the product weight of Reference Example 2 as the standard, when the product weight of each Example and Comparative Example was equal to or less than the weight of Reference Example 2, it was evaluated as "Good," and when it exceeded the weight of Reference Example 2, it was evaluated as "Poor." (1-7) Thickness of flange and body The thickness of the flange and body of the cup-shaped package obtained by injection molding and having a body and flange was measured using a micrometer or vernier calipers. The unit of "thickness" is mm.

[0076] (2) Preparation of resin Propylene-ethylene random copolymer (A) In the invention of the present disclosure, propylene-ethylene random copolymers PP-1 to PP-10 having the physical properties shown in Table 1 from the Novatec series manufactured by Japan Polypropylene Corporation were used as the propylene-ethylene random copolymer (A).

[0077] [Table 1]

[0078] Foaming agent (B) The foaming agent (B) used was "Polythren EE25C," a chemical foaming agent masterbatch manufactured by Eiwa Kasei Co., Ltd. The foaming agent concentration of this masterbatch was 20%. The amount of gas generated after foaming for 20 minutes at a constant temperature of 220°C was 75-90 ml / 2.5 g. This masterbatch is based on low-density polyethylene and contains sodium carbonate and citric acid.

[0079] (3) Preparation and evaluation of resin compositions [Reference Examples 1 and 2] A cup-shaped package having a body and a flange was produced by injection molding using PP-1, a propylene-ethylene random copolymer, without adding blowing agent (B), at a mold temperature of 30°C under the conditions shown in Table 2, taking care to avoid short shots. The evaluation of the cup-shaped package having a body and a flange is shown in Table 2. Here, the cup-shaped packaging body having a body and a flange had a body thickness of 0.4 mm, a flange thickness of 0.6 mm, an opening inner diameter (flange inner diameter) of 80 mm, a bottom inner diameter of 58 mm, a foot inner diameter of 56 mm, a packaging height of 50 mm, a foot height of 5 mm, and a bottom thickness of 0.7 mm. In the item of holding pressure listed in Table 2, "none" indicates that molding was performed without holding pressure, and "yes" indicates that molding was performed with holding pressure. The evaluation result of the appearance of the flange was X for both Reference Examples 1 and 2. The product weight of Reference Example 2 was 7.31 g, and the product weight of Reference Example 2 was used as the standard in the subsequent evaluations.

[0080] [Table 2]

[0081] [Examples 1 to 9 and Comparative Examples 1 to 4] The propylene-ethylene random copolymer (A) and the foaming agent (B) in the weight parts shown in Table 3 were dry blended to produce a resin composition.

[0082] A cup-shaped package having a body and a flange was produced by injection molding a mixture of a propylene-ethylene random copolymer (A) and a blowing agent (B) at a mold temperature of 30°C under the conditions shown in Table 3, taking care not to cause short shots. The evaluation of the cup-shaped package having a body and a flange is shown in Table 3. Here, the cup-shaped packaging body having a body and a flange had a body thickness of 0.4 mm, a flange thickness of 0.6 mm, an opening inner diameter (flange inner diameter) of 80 mm, a bottom inner diameter of 58 mm, a foot inner diameter of 56 mm, a packaging height of 50 mm, a foot height of 5 mm, and a bottom thickness of 0.7 mm.

[0083] In the item of holding pressure listed in Table 3, "none" indicates that molding was performed without holding pressure, and "yes" indicates that molding was performed with holding pressure. Table 3 shows the "appearance" of the cup-shaped package having a body and a flange. The weight of the cup-shaped package with a body and flange is shown in Table 3. The unit of weight is g. If the weight was lighter than the standard weight, it was judged as "Good," and if it was heavier, it was judged as "Poor."

[0084] [Table 3]

[0085] From Examples 1 to 9 in Table 3, it can be seen that resin compositions within the scope of the present disclosure were able to produce cup-shaped packages with excellent surface tension without using dwell pressure, and furthermore, were able to reduce the weight of the packages. In Comparative Example 1, the amount of foaming agent added was insufficient, so the poor appearance could not be eliminated, and in Comparative Example 2, the melt flow rate was insufficient, so a cup-shaped package could not be produced. In Comparative Example 3, a material with high rigidity was used, and a good product was produced, but the product weight was heavier than in Reference Example 2. In Comparative Example 4, the rigidity was significantly low, so the package deformed during removal from the mold, and a good product could not be produced.

[0086] [Explanation of symbols] 1 flange 2. Torso 3 bottom 4 Foot 5 Flange thickness 6 Inner diameter of foot 7. Foot Height 8. Height of package 9 Inner diameter of opening 10 Body thickness 11 Bottom inner diameter 12 Bottom thickness

Claims

1. (i) a melt flow rate (MFR) of 30 to 110 g / 10 min; (ii) a flexural modulus of 1,000 to 1,500 MPa; (iii) 23°C Charpy impact strength of 2.0 to 7.0 kJ / m ２ is A propylene-ethylene random copolymer (A), A polypropylene resin composition comprising more than 1 part by weight and not more than 7 parts by weight of a blowing agent (B) per 100 parts by weight of the propylene-ethylene random copolymer (A).

2. A packaging material comprising the polypropylene resin composition according to claim 1.

3. 3. The package of claim 2, wherein the package is cup-shaped and has a body and a flange.

4. 4. The cup-shaped package according to claim 3, wherein the thickness of the body is 0.3 to 0.7 mm, and the thickness of the flange is 1.5 to 5 times the thickness of the body.

5. 5. The cup-shaped package according to claim 3, wherein the flange has a thickness of 0.5 to 3.5 mm.

6. 3. The method for producing a packaging body according to claim 2, wherein the packaging body is obtained by injection molding without pressure dwell.

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