JPH0575012B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a novel polypropylene foam sheet and its manufacturing method, and relates to a heat-insulating container that can be sterilized with steam by heating and pressing the foam sheet, and a food container that can withstand heating in a microwave oven. The present invention relates to a foam sheet for manufacturing a molded article made of a polypropylene resin foam that can be used as a foam sheet, and a method for manufacturing the same. (Prior Art) In recent years, the appearance of bowls for instant cooked foods or food containers with excellent heat resistance and insulation properties has been awaited. It is well known that food containers are made from foamed sheets and vacuum formed, and these molded products use a large amount of polystyrene resin, which has the advantages of excellent moldability and low cost. There is. However, this foamed food container made of polystyrene resin has poor heat resistance and corrosion resistance, and when heated together with food in a microwave oven, it is greatly deformed, making it unusable. In order to solve this problem, the current situation is to maintain heat resistance by bonding highly heat-resistant polyethylene film or polyester film with a polystyrene resin foam sheet. However, laminating a heat-resistant film on such a foam sheet not only complicates the production process and vacuum forming process of the foam sheet, but also sacrifices its biggest advantage, the price. Therefore, in JP-A-62-94539, 99 to 50% by weight of styrene and 1 to 50% by weight of methacrylic acid were used as resins.
It has been discovered that a foamed sheet of heat-resistant polystyrene copolymerized with polystyrene can be used. However, although the heat resistance is improved compared to a simple polystyrene foam sheet, the heat resistance and oil resistance of the foam sheet is still insufficient even when such heat-resistant polystyrene is used, and for this reason, polypropylene or polyester films are still often pasted together. It was hot. In this case, it was also a problem to use an adhesive that was more expensive and had higher heat resistance. On the other hand, there are also heat-resistant containers made of thermoformed polypropylene foam sheets on the market. However, polypropylene foam sheets have a density of 0.6 g/cc at most and do not have insulation properties, so they cannot hold heated food in their hands, and they do not have the bending strength of heat-resistant polystyrene, so they cannot be used as large containers. I couldn't do it. (Problems to be Solved) Therefore, as a result of various studies in order to solve the above-mentioned drawbacks, the present inventors found that by mixing polypropylene and polystyrene, the characteristics of both, namely heat resistance and oil resistance, and density can be improved. They discovered a foam sheet that is easy to hold in the hand, does not get hot, has bending strength, and can be laminated with polypropylene film without using an adhesive, and completed the present invention. (Means for solving the problem) That is, the present invention provides polypropylene resin 50~
90 parts by weight, 50 to 10 parts by weight of styrene resin,
A polypropylene resin foam sheet for heat molding with a density of 0.1 to 0.5 g/cc and a thickness of 5 mm or less, which is composed of up to 20 parts by weight of a styrene elastomer containing 10% or more of an olefin component. A styrene resin containing at least one of acrylic acid, methacrylic acid, and maleic anhydride and having a styrene component of 75 to 95% by weight and a Vikato softening point of 115° C. or higher is preferable. In addition, as a manufacturing method for this polypropylene resin foam sheet for heat molding, an extruder is used to mix 50 to 90 parts by weight of a polypropylene resin, 50 to 10 parts by weight of a styrene resin, and a styrene resin containing 10% or more of an olefin component. The elastomer is supplied at a ratio of up to 20 parts by weight, and once melted and kneaded in the extruder, an easily volatile blowing agent is supplied at a ratio of 0.2 to 1 mole per 1 kg of mixed resin from the middle of the extruder, and heated. This is a method for producing a polypropylene resin foam sheet for heat molding, which is characterized in that the resin is mixed under pressure, then cooled to a resin temperature, and then discharged into the atmosphere through slits to cause foaming. Further, the present invention will be explained in detail. In other words, polypropylene (hereinafter sometimes abbreviated as PP) has excellent physical properties such as impact resistance, tensile strength, and bending resistance, but it is more rigid than polystyrene.
Various attempts have been made to melt-mix polystyrene with polypropylene in order to replenish it with PS (sometimes abbreviated as PS). However, polypropylene and polystyrene have poor compatibility,
Simply melt-mixing the two causes phase separation, making it impossible to obtain a resin composition with practical strength. However, according to research by the present inventors, polypropylene resin and polystyrene resin
If the easily volatile blowing agent is supplied at a ratio of 90 parts by weight to 40 to 10 parts by weight, and once melted and kneaded in the extruder, the easily volatile blowing agent is supplied at a ratio of 0.2 to 1 mole per 1 kg of mixed resin from the middle of the extruder. It was found that both resins were mixed uniformly. Furthermore, heat-resistant polystyrene 50 to 10 modified with one component of acrylic acid, methacrylic acid, or maleic anhydride is used as the styrene resin.
A resin blended at a ratio of 50 to 90 parts by weight of polypropylene resin to parts by weight is supplied to an extruder, heated and kneaded, and then added to the extruder with 0.1 to 1 mole of easily volatile blowing agent per 1 kg of resin. Supply and heat at a rate of
The present inventors have discovered that when kneaded under pressure, the two types of resins mix well and a good foamed sheet can be obtained, leading to the present invention. The polypropylene resin referred to in the present invention is a propylene homopolymer or a propylene copolymer containing 5 mol% or less of a comonomer, such as a monomer unit such as ethylene, ethyl acrylate, or ethyl methacrylate, or a graft unit of an unsaturated carboxylic acid. Although it contains polymers, it is preferable to use a polypropylene resin with a melt flow index (MFR) (JISK6758) of 5 or less because it foams well. , a homopolymer of propylene and a block polymerization of 5 mol % or less of a comonomer are preferable. Furthermore, the polystyrene resin used in the present invention is a polystyrene of ordinary general grade or a styrene component containing at least one component of acrylic acid, methacrylic acid, and maleic anhydride.
75 to 90% by weight of heat-resistant polystyrene with a Vigatto softening point of 115°C or higher;
Heat resistance deteriorates below 115°C. The Vigatsu softening point referred to here is the softening point measured according to JIS K7206. As mentioned above, the heat-resistant styrene resin has a styrene component containing at least one component of acrylic acid, methacrylic acid, or maleic anhydride.
It is preferable to use the resin described in JP-A-57-72830 (wt%), and a copolymer with maleic anhydride is especially preferable from the viewpoint of foamability and physical properties. Regarding the blending ratio of polypropylene resin and polystyrene resin, the higher the ratio of polypropylene resin, the better the heat resistance and oil resistance will be obtained, but the foamed sheet will have lower bending strength and higher density. Conversely, when the proportion of polystyrene resin increases, a sheet with low density and high stiffness can be obtained, but heat resistance and oil resistance decrease. In order to improve the compatibility between these polypropylene and polystyrene resins, we added an olefin component.
It is effective to use up to 20 parts by weight of styrenic elastomer containing 10% or more. Among these, it is particularly effective to use 5 to 10 parts by weight of an elastomer whose double bonds are hydrogenated after copolymerizing butadiene and styrene. More preferably, it is desirable to use an elastomer modified with 3% or less of acrylic acid or maleic anhydride. When the density of the foam sheet is less than 0.1g/cc,
Not only is the strength of the molded product insufficient, but there may be holes in the molded product due to insufficient elongation during heating and vacuum forming. On the other hand, if it exceeds 0.5 g/cc, there is an economical problem, but if you put food in it and heat it, it will be too hot to hold in your hands. A sheet with a thickness of 5 mm or more has problems because the air bubbles become open cells, resulting in poor thermoformability, and when used as a container, moisture and oil seep into the sheet. Another great advantage of this foam sheet is that it can be directly laminated with polypropylene sheets with a thickness of 20 to 100 microns by heating without the need for adhesives, in order to further improve heat resistance, oil resistance, stiffness, etc. A feature of the production method of the present invention is that polypropylene resin and polystyrene resin, which are originally thought to be immiscible, can be mixed well. The first method is to melt and mix the polypropylene resin and the polystyrene resin in advance, supply a blowing agent thereto, and use the solvent effect to mix the mixture more uniformly. Therefore, it is necessary to use a blowing agent that is easily volatile, and the second feature is the amount used, which is 5 to 10 times higher than the amount corresponding to the desired expansion ratio. The reason is that it is used a lot. Foaming agents include propane butane, pentane, dichlorodifluoromethane, dichlorotrafluoroethane, carbon dioxide gas, etc. that are liquid under pressure at room temperature and evaporate by heating, but among these, foaming agents with boiling points of -50℃ to 50℃ are used.
It is preferred to use aliphatic or halogenated aliphatic hydrocarbons at . The amount of blowing agent to be used is 0.2 to 1 mole per 1 kg of resin. If it is less than 0.2 mole, the kneading property will be insufficient and a good foam will not be obtained, and if it is more than 1.0 mole, the air bubbles will burst and the surface will deteriorate. Only rough sheets are obtained. Furthermore, this manufacturing method is characterized by the mixing of resin and foaming agent.
The process is carried out at 230-250°C and then cooled to 170-200°C to foam. i.e. 30% below the maximum mixing temperature
~80℃, preferably 30~50℃,
It is gentler than the cooling that is done in other foam manufacturing. If kneaded at a high temperature, the melt viscosity of the polypropylene resin and polystyrene resin will increase, resulting in non-uniform mixing, and if the mixture is cooled too much, the flow of the polypropylene will deteriorate, making it impossible to obtain a good foam. The cooled resin is discharged into the atmosphere from the slit-shaped mold, but it is preferable to use a ring-shaped slit, and the thickness of the slit is generally 0.2 to 2 mm. use something The present invention will be explained in more detail with reference to Examples and Comparative Examples. Example 1 Polypropylene resin (Sumitomo Chemical Noblen)
H501) 65 parts by weight and polystyrene resin (Asahi Kasei)
Styron 683) 30 parts by weight and saturated thermoplastic elastomer resin (Asahi Kasei Tuftek M1913)
A mixture of 5 parts by weight and 1 part by weight of finely powdered talc was fed to the extruder. Two extruders with a diameter of 50 mm and a diameter of 65 mm were used, and a die having an annular slit with a diameter of 80 mm and a thickness of 0.5 mm was used. i.e. 50mm
The resin composition is heated and kneaded in an extruder at approximately 240°C.
0.4 mol of dichlorodifluoromethane was injected into 1 kg of the resin composition adjusted to 65 mm in diameter.
1 to the extruder, adjust the resin temperature to 183℃, and
The resin was extruded through an annular slot with a diameter of 80 mm and a thickness of 0.5 mm at a rate of 25 kg per hour. The extruded sheet resin is 1.22mm thick and wide.
It was 640 mm and had a density of 0.46 g/cc. This sheet was molded into the container shape shown in Figure 1, and 150 cc of salad oil was poured into the molded container (container dimensions: length 156 mm x width 126 mm x depth 30 mm) and heated in a microwave oven to make the container heat resistant. The oil content and the amount of oil absorbed into the container were measured. The measurement method is a microwave oven (Sharp: R-
9000600W) and heated for 8 minutes until the temperature reached 140°C, the container was immediately removed from the microwave oven, and after removing the salad oil from the container, the shape and dimensional changes of the container were measured. Among the measurement points, among length, width, and depth, measurements were made at the depth part where the dimensional change was particularly large. In addition, the conditions and method for measuring the bending elastic modulus of the sheet are: bending speed: 50 mm/min, span interval: 30 mm,
Jig tip: 3.2Rmm, test piece: original fabric thickness t x 50W x
I followed 150Lmm. As a result of measuring the heat resistance of the container and the amount of oil absorbed into the container, there was no change in shape or dimension. Also, the amount of oil absorbed into the container was approximately 2.7 g. The bending elastic modulus of the sheet was 6400 Kgf/cm ² in the machine direction and 6440 Kgf/cm ² in the width direction. Example 2 Polypropylene resin (Sumitomo Chemical Noblen)
FH1015) 75 parts by weight, polystyrene resin (Asahi Kasei Styron 666) 20 parts by weight, and saturated thermoplastic elastomer resin (Asahi Kasei Tuftec)
A mixture of 5 parts by weight of H1041) and 1 part by weight of finely powdered talc was supplied to an extruder. The following procedure was carried out in the same manner as in Example 1. That is, the resin composition was heated and kneaded in a 50 mm extruder,
0.38 mol of butane was injected into 1 kg of the resin composition adjusted to approximately 240℃, and fed to an extruder with a diameter of 65 mm. The resin temperature was adjusted to 190℃ and the resin was extruded through the slits at a rate of 22 kg for 1 hour. did. The extruded resin sheet has a thickness of 1.17mm, a width of 640mm, and a density of 0.43g/
It was cc. As a result of measuring the heat resistance of the container and the amount of oil absorbed into the container, there was no change in shape or dimension. Also, the amount of oil absorbed into the container was approximately 0.8 g. The bending elastic modulus of the sheet was 7870 Kgf/cm ² in the machine direction and 7430 Kgf/cm ² in the width direction. Example 3 Polypropylene resin (block copolymer)
MFR3 Noblen AH585A manufactured by Sumitomo Chemical Co., Ltd.) 80 parts by weight, impact-resistant polystyrene resin (Nippon Steel Chemical Co., Ltd. S-61) 15 parts by weight, and saturated thermoplastic elastomer resin (Asahi Kasei Co., Ltd. Tuftek H1041) 5
A mixture of parts by weight and 1 part by weight of finely powdered talc was fed to an extruder. The following procedure was carried out in the same manner as in Example 1. That is, the resin composition was heated and kneaded in a 50 mm extruder,
0.33 mol of butane was injected into 1 kg of resin composition adjusted to approximately 240°C, then fed to an extruder with a diameter of 65 mm, the resin composition was adjusted to 187°C, and 22 kg was heated for 1 hour.
The resin was extruded from the slit at a rate of . The extruded sheet resin has a thickness of 1.37 mm, a width of 640 mm, and a density of
It was 0.49g/cc. As a result of measuring the heat resistance of the container and the amount of oil absorbed into the container, there was no change in shape or dimension. Also, the amount of oil absorbed into the container was approximately 1.3 g. The bending elastic modulus of the sheet was 7250 Kgf/cm ² in the machine direction and 7090 Kgf/cm ² in the width direction. Example 4 Polypropylene resin (Mitsubishi Yuka/Noblen)
MH-8) 70 parts by weight, polystyrene resin (Asahi Kasei Styron 666) 25 parts by weight, and saturated thermoplastic elastomer resin (Ciel Kagaku Kraton)
A mixture of 5 parts by weight of 1675) and 1 part by weight of finely powdered talc was fed to the extruder. The following procedure was carried out in the same manner as in Example 1. That is, the resin composition was heated and kneaded in a 50 mm extruder,
0.43 mol of dichlorodifluoromethane (Freon 12) was injected into 1 kg of the resin composition adjusted to about 240°C, then fed to an extruder with a diameter of 65 mm, the resin composition was adjusted to 181°C, and 26 kg of The resin was extruded through the slits in proportion. The extruded sheet resin is
It had a thickness of 1.20 mm, a width of 640 mm, and a density of 0.35 g/cc. As a result of measuring the heat resistance of the container and the amount of oil absorbed into the container, a change in shape was observed, but no dimensional change was observed. In addition, the amount of oil absorbed into the container was approximately 2.8 g. Also, the bending elastic modulus of the sheet is 5260 in the machine direction.
Kgf/cm ² , and the width direction was 5090 Kgf/cm ² . Example 5 Polypropylene resin (block copolymer)
MFR3 Noblen AH585A manufactured by Sumitomo Chemical Co., Ltd.) 65 parts by weight and heat-resistant polystyrene resin (maleic anhydride copolymer Vikatsu softening point 136℃ Idemitsu Petrochemical Co., Ltd.)
30 parts by weight of Moamax UG830) and saturated thermoplastic elastomer (Tuftek, manufactured by Asahi Kasei)
A mixture of 5 parts by weight of H1041) and 1 part by weight of talc was supplied to an extruder. The same extruder as in Example 1 was used. The resin composition was heated and kneaded in an extruder with a diameter of 50 mm, and 0.52 mol of liquefied butane was injected into 1 kg of resin from the tip of the 50 mm EYT, and then fed into an extruder with a diameter of 65 mm, and the resin temperature was adjusted to 185 ° C. The resin was extruded through the slit at a rate of 25 kg for 1 hour. The extruded resin sheet was taken out in the same manner as in Example 1 and had a thickness of 1.48 mm, a width of 640 mm, and a density of 0.48.
I rolled up a sheet of g/cc. The heat resistance of the container and the amount of oil absorbed into the container were measured using the same method as in Example 1, and as a result, there was no change in shape or dimension.
Also, the amount of oil absorbed into the container was about 3 g. The flexural modulus of the sheet was determined in the same manner as in Example 1. 3040Kgf/cm ² in flow direction, 4070Kg in width direction
It was f/cm ² . Example 6 65 parts by weight of polypropylene resin (homopolymer MFR2.5 Noblen FS2011D manufactured by Sumitomo Chemical Co., Ltd.) and 30 parts by weight of heat-resistant polystyrene resin (maleic anhydride copolymer Vikatsu softening point 136°C Moamax UG830 manufactured by Idemitsu Petrochemical Co., Ltd.) A mixture of 5 parts by weight of a saturated thermoplastic elastomer (Tuftek H1041 manufactured by Asahi Kasei Corporation) and 1 part by weight of talc was supplied to an extruder. The same extruder as in Example 1 was used. The resin composition was heated and kneaded in an extruder with a diameter of 50 mm, and 0.33 mol of liquefied dichlorodifluoromethane (Freon 12) was press-injected into 1 kg of resin adjusted to about 240°C from the tip of the 50 mm EYT, and then extruded into an extruder with a diameter of 65 mm. Supply the resin to the machine and adjust the resin temperature to 190℃ for 1 hour.
Resin was extruded through the slit at a rate of 25 kg. The extruded resin sheet was taken up in the same manner as in Example 1 and rolled up into a sheet having a thickness of 1.33 mm, a width of 640 mm, and a density of 0.47 g/cc. The heat resistance of the container and the amount of oil absorbed into the container were measured using the same method as in Example 1, and as a result, there was no change in shape or dimension. Also, the amount of oil absorbed into the container was approximately 2.5 g. The flexural modulus of the sheet was determined in the same manner as in Example 1. The flow direction was 4430 Kgf/cm ² and the width direction was 4280 Kgf/cm ² . Example 7 Polypropylene resin (homopolymer MFR2.5
65 parts by weight of Noblen FS2011D (manufactured by Sumitomo Chemical Co., Ltd.), 30 parts by weight of heat-resistant polystyrene resin (maleic anhydride copolymer Vikatto softening point 136°C, Moamax UG830 manufactured by Idemitsu Petrochemical Co., Ltd.) and styrene-based elastomer resin (SIS-manufactured by Japan Synthetic Rubber Co., Ltd.) A mixture of 5 parts by weight of 5000) and 1 part by weight of talc was supplied to an extruder. The same extruder as in Example 1 was used. Heat and knead the resin composition in an extruder with a diameter of 50 mm,
1Kg of resin adjusted to approximately 240℃ from the tip of 50mmEYT
0.52 mol of butane was injected into the resin, and the resin temperature was 182
℃ and extruded the resin through the slit at a rate of 25 kg for 1 hour. Example 1 Extruded sheet-shaped resin
Thickness 1.40mm, width 640mm, density
A sheet of 0.48 g/cc was rolled up. The heat resistance of the container and the amount of oil absorbed into the container were measured using the same method as in Example 1, and as a result, there was no change in shape or dimension. Also, the amount of oil absorbed into the container was approximately 1.0 g. The flexural modulus of the sheet was determined in the same manner as in Example 1. 6570Kgf/cm ² in flow direction, 5340Kgf/cm 2 in width direction
It was Kgf/ ^cm2 . Example 8 70 parts by weight of polypropylene resin (homopolymer MFR2 Noblen FS2011A manufactured by Sumitomo Chemical Co., Ltd.) and heat-resistant polystyrene resin (maleic anhydride copolymer Vikatsu, softening point 133°C, Dilarc manufactured by Sekisui Plastics Co., Ltd.)
A mixture of 20 parts by weight of DL#332), 10 parts by weight of a styrene elastomer resin (Tuftek M1913 manufactured by Asahi Kasei Corporation) and 1 part by weight of talc was supplied to an extruder. The same extruder as in Example 1 was used. Heat and knead the resin composition in an extruder with a diameter of 50 mm,
1Kg of resin adjusted to approximately 240℃ from the tip of 50mmEYT
0.52 mol of butane was injected into the resin, and the resin temperature was 190.
℃ and extruded the resin through the slit at a rate of 22 kg for 1 hour. Example 1 Extruded sheet-shaped resin
Thickness 1.15mm, width 640mm, density
A sheet of 0.45 g/cc was rolled up. The heat resistance of the container and the amount of oil absorbed into the container were measured using the same method as in Example 1, and as a result, there was no change in shape or dimension. Also, the amount of oil absorbed into the container was approximately 0.5 g. The flexural modulus of the sheet was determined in the same manner as in Example 1. 4920Kgf/cm ² in flow direction, 3650Kgf/cm 2 in width direction
It was Kgf/ ^cm2 . Example 9 45 parts by weight of polypropylene resin (homopolymer MFR2.5 Noblen FS2011D manufactured by Sumitomo Chemical Co., Ltd.) and 45 parts by weight of heat-resistant polystyrene resin (maleic anhydride copolymer Vikatsu softening point 136°C Moamax UG830 manufactured by Idemitsu Petrochemical Co., Ltd.) A mixture of 10 parts by weight of a saturated thermoplastic elastomer (Tuftek H1041 manufactured by Asahi Kasei Corporation) and 1 part by weight of Kuruk was supplied to an extruder. The same extruder as in Example 1 was used. The resin composition was heated and kneaded using an extruder with a diameter of 50 mm, and 0.45 mol of carbon dioxide (CO ₂ ) was press-injected from the tip of a 50 mm EYT to 1 kg of resin, which was adjusted to about 240°C, and the resin temperature was adjusted to 180°C. The resin was extruded through the slit at a rate of 27 kg per hour. The extruded sheet-shaped resin was taken out in the same manner as in Example 1 and was made to a thickness of 1.23 mm.
A sheet with a width of 640 mm and a density of 0.35 g/cc was rolled up. The heat resistance of the container and the amount of oil absorbed into the container were measured using the same method as in Example 1, and as a result, there was no dimensional change except for a slight change in shape.
Also, the amount of oil absorbed into the container was approximately 1.2 g.
The flexural modulus of the sheet was determined in the same manner as in Example 1. 4470Kgf/cm ² in flow direction, 3490Kg in width direction
It was f/cm ² . Example 10 60 parts by weight of polypropylene resin (homopolymer MFR2 Noblen FS2011A manufactured by Sumitomo Chemical), 30 parts by weight of transparent, heat-resistant resin (styrene and methacrylic acid copolymer resin AXT100 manufactured by Asahi Kasei) and saturated thermoplastic elastomer (manufactured by Asahi Kasei) tough tech
A mixture of 10 parts by weight of H1041) and 1 part by weight of talc was supplied to an extruder. The same extruder as in Example 1 was used. Heat and knead the resin composition in an extruder with a diameter of 50 mm,
1Kg of resin adjusted to approximately 240℃ from the tip of 50mmEXT
0.6 mol of liquefied butane was injected into the resin, and the resin temperature was 182.
℃ and extruded the resin through the slit at a rate of 25 kg for 1 hour. Example 1 Extruded sheet-shaped resin
Thickness 1.64mm, width 640mm, density
A sheet of 0.40 g/cc was rolled up. The heat resistance of the container and the amount of oil absorbed into the container were measured using the same method as in Example 1, and as a result, there was no change in shape or dimension. Also, the amount of oil absorbed into the container was approximately 2.0 g. The flexural modulus of the sheet was determined in the same manner as in Example 1. Flow direction is 4330Kgf/ ^cm2 , width direction is 3880Kgf/cm2
It was Kgf/ ^cm2 . As described above, a CPP film having a thickness of 30 to 70 microns was pressed onto the foamed sheets obtained in Examples 1 to 10 while contacting them with a Teflon-coated heating roll at about 180°C, and this laminated sheet was laminated with the foamed sheet. was molded so that the CPP film was placed on the inner surface of the container, and the heat resistance and oil absorption were similarly tested. As a result, the heat resistance improved only slightly, but the oil absorption was almost 0. Comparative example 1 Polystyrene resin (Asahi Kasei Styron 683)
100 parts by weight and 1 part by weight of finely powdered talc were fed into the extruder. The following procedure was carried out in the same manner as in Example 1. Heat and knead the resin composition in a 50 mm extruder,
0.8 mol of butane was injected into 1 kg of resin adjusted to approximately 230°C from the tip, and then fed to a 65 mm extruder, the resin temperature was adjusted to 178°C, and resin was extruded through the slit at a rate of 27 kg for 1 hour. . The extruded sheet resin is 1.85mm thick and wide.
It was 640 mm and had a density of 0.25 g/cc. As a result of measuring the heat resistance of the container and the amount of oil absorbed into the container, the shape change was large and the dimensional change was 10 mm. Also, the amount of oil absorbed into the container was approximately 14 kg. Also, the bending elastic modulus of the sheet is 1580 in the flow direction.
Kgf/cm ² , and the width direction was 1240 Kgf/cm ² . Comparative Example 2 Polypropylene resin (Noblen manufactured by Sumitomo Chemical)
FS2011D) 25 parts by weight polystyrene resin (Asahi Kasei Stylon 683) 70 parts by weight and saturated thermoplastic elastomer resin (Asahi Kasei Tuftec)
A mixture of 5 parts by weight of H1041) and 1 part by weight of finely powdered talc was supplied to an extruder. The following steps were carried out in the same manner as in Example 1. The resin composition was heated and kneaded in a 50 mm extruder, and butane was added to 1 kg of resin, which was adjusted to about 235°C from the tip.
0.5 mol was injected, then fed to a 65 mm extruder,
The resin temperature was adjusted to 180°C, and the resin was extruded through the slit at a rate of 25 kg for 1 hour. The extruded sheet resin is 1.45mm thick and wide.
It was 640 mm and had a density of 0.37 g/cc. As a result of measuring the heat resistance of the container and the amount of oil absorbed into the container, there was a change in shape, and the dimensional change was 7 mm. Also, the amount of oil absorbed into the container was approximately 11.5 g. Also, the bending elastic modulus of the sheet is 3470 kg in the machine direction.
f/cm ² , and the width direction was 2850 Kgf/cm ² . Comparative Example 3 Polypropylene resin (Noblen manufactured by Sumitomo Chemical)
A mixture of 100 parts by weight of FS2011A) and 1 part by weight of finely powdered talc was supplied to an extruder. The following procedure was carried out in the same manner as in Example 1. The resin composition was heated and kneaded in a 50 mm extruder, and butane was added to 1 kg of resin, which was adjusted to about 240°C from the tip.
0.032 mol was injected, and then the resin was fed into a 65 mm extruder, the resin temperature was adjusted to 185°C, and the resin was extruded through the slit at a rate of 22 kg for 1 hour. The extruded resin sheet had a thickness of 1.72 mm, a width of 640 mm, and a density of 0.5 g/cc. As a result of measuring the heat resistance of the container and the amount of oil absorbed into the container, there was no change in shape or dimension.
In addition, the amount of oil absorbed into the container was approximately 1.3 g.
In addition, the bending elastic modulus of the sheet is 9700 kgf/
cm ² , and the width direction was 8570 Kgf/cm ² . Furthermore, when this sheet was molded into the container mold shown in FIG. 1, it sagged during preheating and had poor mold release. Comparative example 4 Polypropylene resin (homopolymer MFR2
(Sumitomo Chemical Noblen FS2011A) 22 parts by weight and heat-resistant polystyrene resin (styrene, maleic anhydride copolymer Vikatsu, softening point 133℃ Sekisui Plastics)
68 parts by weight of Dylarc DL#332) and saturated thermoplastic elastomer (Tuftek, manufactured by Asahi Kasei)
A mixture of 10 parts by weight of H1041) and 1 part by weight of talc was supplied to an extruder. The same extruder as in Example 1 was used. 50
The resin composition was heated and kneaded in a mm extruder, and 50 mm
0.86 mol of butane is injected into 1 kg of resin adjusted to approximately 230℃ from the tip of the EXT, then fed to a 65 mm extruder, the resin temperature is adjusted to 180℃, and 26 kg is heated for 1 hour.
The resin was extruded from the slit at a rate of . The extruded sheet-shaped resin was taken off in the same manner as in Example 1 and its thickness was measured.
A sheet of 1.38 mm, width 640 mm, and density 0.29 g/cc was rolled up. The heat resistance of the container and the amount of oil absorbed into the container were measured using the same method as in Example 1, and as a result, there was a change in shape and a dimensional change of 7 mm. Also, the amount of oil absorbed into the container was about 12 g. The bending elastic modulus of the sheet was determined in the same manner as in Example 1. The flow direction was 3650 Kgf/cm ² and the width direction was 2720 Kgf/cm ² . Comparative Example 5 A mixture of 100 parts by weight of polypropylene resin (homopolymer MFR2, Noblen FS2011A manufactured by Sumitomo Chemical Co., Ltd.), 1 part by weight of talc, and 1 part by weight of Die Blow No. 2 (Dainichiseika Co., Ltd.) as a foaming agent was supplied to an extruder. did. An extruder with a diameter of 65 mm was used, and a die with an annular slit of 105 mm in diameter and 0.65 mm in thickness was used as the extruder. The resin temperature was adjusted to 175°C, and the resin was extruded through the slit at a rate of 20 kg for 1 hour. By pulling the extruded sheet-shaped resin along a cooled cylinder with a diameter of 220 mm, the thickness
A sheet of 1.47 mm, width 690 mm, and density 0.59 g/cc was rolled up. The heat resistance of the container and the amount of oil absorbed into the container were measured using the same method as in Example 1, and as a result, there was no change in shape or dimension. Also, the amount of oil absorbed into the container was approximately 1.5g. The flexural modulus of the sheet was determined in the same manner as in Example 1. The flow direction is
It was 10,700 Kgf/cm ² and 9,150 Kgf/cm ² in the width direction. Furthermore, when this sheet was molded into the container mold shown in FIG. 1, it sagged during preheating and had poor mold release. Comparative Example 6 A mixture of 100 parts by weight of a transparent, heat-resistant resin (styrene, methacrylic acid copolymer resin AX-T100 manufactured by Asahi Kasei) and 1.5 parts by weight of talc was supplied to an extruder. An extruder with a diameter of 90 mm and a diameter of 115 mm was used, and a die with an annular slit of 140 mm in diameter and 0.65 mm in thickness was used as an extruder. The resin composition was heated and kneaded in an extruder with a diameter of 90 m, and 0.86 mol of liquefied butane was injected into 1 kg of resin adjusted to approximately 240°C from the tip of the 90 mm EXT, and then supplied to an extruder with a diameter of 115 mm, and the resin temperature was adjusted to 180°C. ℃ and extruded the resin through the slit at a rate of 80 kg for 1 hour. The extruded sheet-shaped resin is taken along a cylinder with an outer diameter of 640 mm, thickness is 2.16 mm, width is 1000 mm, and density
A sheet of 0.19 g/cc was rolled up. The heat resistance of the container and the amount of oil absorbed into the container were measured using the same method as in Example 1, and as a result, the large shape change and dimensional change were 9 mm. After measuring the depth part, deformation (Table -
1) was deformed by 9mm. Also, the amount of oil absorbed into the container was about 15 g. The flexural modulus of the sheet was determined in the same manner as in Example 1. Flow direction is 1710Kgf/
cm ² , and the width direction was 1180 Kgf/cm ² . The above results are shown in Table 1.

【table】

【table】

[Table] (Effects) As described above, the present invention is to obtain a foamed polypropylene sheet having a lower density and heat resistance than a resin composition in which a polystyrene resin is uniformly mixed with a polypropylene resin. By vacuum-forming food containers using the material, it is possible to provide containers with heat resistance, oil resistance, and bending strength.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a container made of the foamed sheet of the present invention used in Examples of the present invention, and FIG. 2 is a partially sectional side view of the same container.

Claims (1)

[Scope of Claims] 1. A polypropylene resin foam sheet for thermoforming made of a polypropylene resin, a styrene resin, and a styrene elastomer containing 10% or more of an olefin component, wherein the polypropylene resin contains 50 to 90 parts by weight of the polypropylene resin. On the other hand, it is composed of 50 to 10 parts by weight of styrene resin and up to 20 parts by weight of the styrene elastomer, and has a density of 0.1 to 10 parts by weight.
Polypropylene resin foam sheet for thermoforming with a weight of 0.5g/cc and a thickness of 5mm or less. 2. The polystyrene resin according to claim 1, wherein the polystyrene resin contains at least one component of acrylic acid, methacrylic acid, and maleic anhydride, has a styrene component of 75 to 95% by weight, and has a Vikato softening point of 115°C or higher. Polypropylene resin foam sheet for heat molding. 3. Supply 50 to 10 parts by weight of a styrene resin and 20 parts by weight of a styrene elastomer containing 10% or more of an olefin component to 50 to 90 parts by weight of a polypropylene resin to an extruder. Once melted and kneaded, a readily volatile blowing agent is supplied at a ratio of 0.2 to 1 mole per 1 kg of mixed resin from the middle of the extruder, mixed under heat and pressure, and then the resin temperature is cooled and the resin is melted from the pores. A method for producing a polypropylene resin foam sheet for heat molding, which comprises blowing the sheet into the atmosphere.