JP7283135B2 - METHOD FOR MANUFACTURING HEAT SEAL FILM - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a heat-sealable film using a T-die molding machine. More specifically, it relates to a method for producing a heat-sealable film under specific production conditions.

As one type of packaging container, a multi-chamber container having a partition inside has been proposed. A multi-chamber container is a container having a partition formed therein, and is formed by bag-making a resin film or sheet by heat-sealing.
Such multi-chamber containers are used for beverages, pharmaceuticals, cosmetics, chemicals, miscellaneous goods, etc., and are used by mixing two or more components just before use. Especially in the medical field, prevention of denaturation in drug mixing, convenience of preparation work at clinical sites, prevention of bacterial contamination and contamination, prevention of mistakes in drug preparation, rapid response in emergency use, pharmacists and nurses Multi-chamber containers are widely used from the viewpoint of reducing the burden of

In the case of a multi-chamber container as described above, the peripheral part must have sufficient heat seal strength (strong seal: approximately 29.4 N / 15 mm width or more), but the partition inside the container , Resin films or sheets are difficult to separate from each other during production and transportation, and heat seal strength (weak seal: approximately 2.9 N ~ 9.8 N/15 mm width), and these must be compatible.
Inflation molding using a circular die (inflation die) is known as a molding method that achieves both of these heat-sealing strengths. It's becoming

Although it is a molding method using a circular die, a method of using a mixture of a polypropylene resin and a resin other than polypropylene is known as a method of stably developing a weak seal. For example, in JP-A-09-099037 (Patent Document 1), a multi-chamber medical container using a polymer composition comprising polypropylene having a metallocene-catalyzed melting point of 140° C. or less and an olefinic thermoplastic elastomer or a styrene thermoplastic elastomer. is disclosed. The technique described in Patent Document 1 is useful as a technique for developing a weak seal strength in the partition wall of a multi-chamber container, but on the other hand, the seal strength in the peripheral portion requiring a strong seal is 29.4 N/15 mm width. and it can be said that it is difficult to develop sufficient strong seal strength. Moreover, since a circular die is used, mass production is difficult.

Further, Japanese Patent Application Laid-Open No. 2010-229256 (Patent Document 2) discloses a multi-chamber container made of a resin composition obtained by mixing two types of polypropylene resin and an ethylene-α-olefin copolymer component at a specific ratio. disclosed. The technique described in Patent Document 2 is capable of forming a weak seal and a strong seal, but requires very severe sealing conditions of 4 seconds at 225° C. in order to develop a strong seal. There was a problem with processability. Moreover, since a circular die is used, mass production is difficult.

On the other hand, Japanese Patent Application Laid-Open No. 2003-052791 (Patent Document 3) discloses a multi-chamber container whose heat-sealed portion is made of a polypropylene-based resin composition obtained by specific two-stage polymerization. However, in the technique described in Patent Document 3, blocking between molded heat-seal layers tends to occur remarkably, resulting in poor workability. Moreover, since a circular die is used, mass production is difficult.
In addition, Japanese Patent Application Laid-Open No. 2006-021504 (Patent Document 4) discloses that the heat-sealable sealing layer includes a propylene/α-olefin random copolymer having a crystalline melting point of 135 to 145°C and a A flexible plastic film is disclosed which is characterized by a mixture with a polypropylene homopolymer. However, the technique described in Patent Document 4 has a problem that the temperature range in which a weak seal strength can be formed is as narrow as 2°C. Moreover, since a circular die is used, mass production is difficult.
Further, Japanese Patent Application Laid-Open No. 2001-226499 (Patent Document 5) describes a propylene/α-olefin copolymer (A) and a propylene/α-olefin having a different α-olefin content from the copolymer (A). Disclosed is an easily peelable film comprising a mixture of a copolymer (B) and/or a propylene homopolymer (C). However, the technique described in Patent Document 5 requires a long time of 10 seconds to develop a weak seal, and cannot be said to be an industrially realistic technique. Moreover, since a circular die is used, mass production is difficult.

On the other hand, films having weak sealability produced by T-die molding are often used as lid materials in combination with highly rigid containers, but it is often difficult to form strong seals with these films. Japanese Patent Application Laid-Open No. 2014-184654 (Patent Document 6) discloses an easily peelable multilayer film produced by T-die molding. However, the technique described in Patent Document 6 cannot form a strong seal, so its application is limited to lid materials and the like.

JP-A-09-099037 JP 2010-229256 A JP 2003-052791 A JP 2006-021504 A JP-A-2001-226499 JP 2004-184654 A

Under such circumstances, the object of the present invention is to provide a method for controlling the heat seal strength according to the heat seal conditions, which has good moldability and forms a weak seal of 2.9 to 9.8 N/15 mm width over a wide temperature range. The object of the present invention is to provide a method for producing a heat-sealing film capable of forming a strong seal of 29.4 N/15 mm width at a practical heat-sealing temperature of 160°C or less.

In order to solve the above-mentioned problems, the present inventors have found that the propylene-based resins used for the sealant layer (heat seal layer) are a polypropylene-based resin that is a low-melting multistage polymer containing components with different MFRs, and a polypropylene-based resin with a high melting point. By combining system resins in a specific range, further defining the relationship between the melting peak temperature, melting peak temperature difference and melt flow rate in these polypropylene resins, and further setting the cooling roll temperature in T die molding to 30 ° C. or less, We have found a method for producing a film that can be mass-produced, has good formability, has a wide weak sealing temperature range, and can exhibit strong sealing at a practical heat sealing temperature of 160 ° C. or less, and the present invention. Completed.

That is, according to the first aspect of the present invention, there is provided a method for producing a film having at least one heat-sealable layer, the heat-sealable layer comprising 30 to 95% by weight of the following polypropylene-based resin (A) component and the following polypropylene 5 to 70% by weight of the system resin (B) component, and optionally 0 to 100 parts by weight of the elastomer (C) with respect to a total of 100 parts by weight of the polypropylene resin (A) and the polypropylene resin (B) Furthermore, a resin composition having a melting peak temperature difference of 20 ° C. or more between the polypropylene resin (A) and the polypropylene resin (B) is cooled and solidified using a cooling roll of 30 ° C. or less in a T-die molding machine to form a film. It is provided by a method for producing a heat-sealing film that produces
Component (A): A multi-stage polymer satisfying the following requirements (A-1) and (A-2), wherein the first component of the multi-stage polymer is (a-1) to (a-3) Polypropylene resin that meets the requirements.
(A-1) Melt flow rate (MFR) (JIS K7210, temperature 230 ° C., 2.16 kg load) is 1 g / 10 minutes or more and 50 g / 10 minutes or less (A-2) Melting peak temperature by DSC 110°C or more and less than 140°C.
(a-1) Melt flow rate (MFR) (JIS K7210, temperature 230 ° C., 2.16 kg load) is 0.1 g / 10 minutes or more and 10 g / 10 minutes or less (a-2) Melting peak by DSC The temperature should be 110°C or higher and less than 140°C.
(a-3) The first component is 5 parts by weight or more and 95 parts by weight or less per 100 parts by weight of the polypropylene resin (A).
Component (B): A polypropylene resin that satisfies the following requirements (B-1) and (B-2).
(B-1) Melt flow rate (MFR) (JIS K7210, 230° C., 2.16 kg load) is 0.5 g/10 minutes or more and 25 g/10 minutes or less.
(B-2) The melting peak temperature measured by DSC is 140° C. or higher.

Further, according to the second aspect of the present invention, in the first aspect, the MFR of the second component calculated from the MFR of the entire polypropylene resin (A) and the MFR of the first component is 50 g / It is provided by a method for producing a heat-sealing film, which is 10 minutes or more and 10000 g/10 minutes or less.

According to a third aspect of the present invention, there is provided a method for producing a heat-sealing film according to the first or second aspect, wherein the polypropylene-based resin (A) is a metallocene-based polymer.

Further, according to a fourth invention of the present invention, in any one of the first to third inventions, the elastomer (C) is an ethylene-α-olefin copolymer and/or a styrene elastomer and/or propylene. - A method for producing a heat-sealable film that is an α-olefin copolymer.

According to the production method of the present invention, mass production is possible, moldability is good, the resulting film has a wide weak sealing temperature range, and exhibits strong sealing at a practical heat sealing temperature of 160 ° C. or less. Therefore, the sealing strength can be easily controlled by the sealing temperature, which is industrially effective. Therefore, the film obtained by the production method of the present invention exhibits suitable performance in applications such as multi-chamber containers and lid materials.

Embodiments of the present invention will be described in detail below. It is not limited to the described contents.

[Resin composition]
The heat-sealing resin composition used in the present invention comprises 30 to 95% by weight of polypropylene resin (A) component, 5 to 70% by weight of polypropylene resin (B) component, polypropylene resin (A) and polypropylene resin ( A resin composition optionally containing 0 parts by weight or more and 100 parts by weight or less of an elastomer (C) with respect to a total of 100 parts by weight of B), wherein the melting peak temperature of the polypropylene resin (A) and the polypropylene resin (B) difference is 20°C or more. The properties and the like required for each resin component will be described below.

1. Polypropylene resin (A)
The polypropylene-based resin (A) is a multi-stage polymer, and the polypropylene-based resin of each component constituting the multi-stage polymer is a propylene homopolymer and propylene and an α having 2 to 12 carbon atoms (excluding 3 carbon atoms) - At least one polymer selected from the group consisting of copolymers of olefins, preferably a propylene-ethylene copolymer or a propylene-ethylene-butene copolymer. Any multistage polymer can be used without any limitation as long as it is composed of at least two components. A two-component system, that is, a multistage polymer containing a first component and a second component, which is a preferred multistage polymer in the present invention, will be described below. The order of the multi-stage polymerization may be either the first component described below or the second component described below.

Moreover, the catalyst for producing the polypropylene-based resin (A) is not particularly limited, but the polypropylene-based resin (A) is preferably a metallocene-based polypropylene-based resin.
It is known that molecular weight, molecular weight distribution, branched structure, and other structural characteristics of ethylene-based polymers and propylene-based polymers can be controlled by selecting a catalyst. It is also possible to distinguish between types, for example, an ethylene-based polymer or a propylene-based polymer polymerized with a metallocene catalyst is called a metallocene-based ethylene-based polymer or a metallocene-based propylene-based polymer, or a catalyst other than a metallocene catalyst The ethylene-based polymer and propylene-based polymer polymerized in are sometimes referred to as non-metallocene-based ethylene-based polymer and non-metallocene-based propylene-based polymer.

The polypropylene resin (A) is a multistage polymer that satisfies the following requirements (A-1) and (A-2). Also, the first component of the multistage polymer satisfies the requirements (a-1) to (a-3).
1-1) Requirement (A-1): Melt flow rate (230°C, 2.16 kg load)
The melt flow rate of the entire polypropylene resin (A) (230° C., 2.16 kg load) is 1.0 g/10 min or more and 50 g/10 min or less, preferably 1 to 30 g/10 min, more preferably 1 to 20 g/10 min, particularly preferably 1 to 15 g/10 min. If the melt flow rate is 1.0 g/10 minutes or more, the load during molding of the heat-sealing film does not increase, and the molding of the laminate itself becomes easy. If it is 50 g/10 minutes or less, molding stability during molding of a heat-sealable film is good.

1-2) Requirement (A-2): Melting peak temperature by differential scanning calorimetry (DSC) The melting peak temperature (by DSC) of the polypropylene resin (A) is 110 ° C. or more and less than 140 ° C., preferably 115 °C or higher and lower than 140 °C, more preferably 120 °C or higher and lower than 140 °C, and particularly preferably 120 °C or higher and lower than 135 °C. Note that the melting peak temperature may also be referred to as the melting point. If the melting peak temperature is 110° C. or higher, the heat-sealing film obtained by combining with the polypropylene resin (B) is heat-sealed with each other during sterilization at a high temperature of 121° C. for 30 minutes, for example. It is difficult for unintended fusion of parts that are not in contact with each other. Further, if the melting peak temperature is less than 140° C., it is easy to obtain a wide heat sealing temperature range in which the heat sealing strength becomes 2.9 to 9.8 N/15 mm width by combining with the polypropylene resin (B).

1-3) Requirement (a-1): Melt flow rate of the first component (230°C, 2.16 kg load)
The melt flow rate (230° C., 2.16 kg load) of the first component of the polypropylene resin (A) is 0.1 g/10 minutes or more and 10 g/10 minutes or less, preferably 0.5 g/10 minutes. Above, 10 g/10 minutes or less, more preferably 1 g/10 minutes or more and 10 g/10 minutes or less. If the melt flow rate of the first component is 0.1 g/10 minutes or more, the load during molding of the heat-sealing film does not increase, and the molding of the laminate itself becomes easy. If it is 10 g/10 minutes or less, molding stability during molding of a heat-sealable film is good.

1-4) Requirement (a-2): Melting peak temperature of the first component by differential scanning calorimetry (DSC) The melting peak temperature of the first component of the polypropylene resin (A) (by DSC) is 110 ° C. 140°C or more, preferably 115°C or more and less than 140°C, more preferably 120°C or more and less than 140°C, and particularly preferably 120°C or more and 135°C or less. If the melting peak temperature is 110° C. or higher, the heat-sealing film obtained by combining with the polypropylene resin (B) is heat-sealed with each other during sterilization at a high temperature of 121° C. for 30 minutes, for example. It is difficult for unintended fusion of parts that are not in contact with each other. Further, if the melting peak temperature is less than 140° C., it is easy to obtain a wide heat sealing temperature range in which the heat sealing strength becomes 2.9 to 9.8 N/15 mm width by combining with the polypropylene resin (B).

1-5) Requirement (a-3): Ratio of the first component to 100 parts by weight of the polypropylene resin (A) The ratio of the first component to 100 parts by weight of the polypropylene resin (A) is 5 parts by weight or more and 95 parts by weight parts by weight or less, preferably 20 to 90 parts by weight, more preferably 30 to 90 parts by weight. When the ratio of the first component to 100 parts by weight of the polypropylene resin (A) is 5 parts by weight or more, the molding stability during heat-sealing film molding is good, and the first component to 100 parts by weight of the polypropylene resin (A) When the ratio of component 1 is 95 parts by weight or less, it is easy to obtain a wide heat sealing temperature range in which the heat sealing strength becomes 2.9 to 9.8 N/15 mm width by combining with the polypropylene resin (B).

2. Polypropylene resin (B)
The polypropylene-based resin (B) is composed of one or more propylene-based polymers, and when it is composed of two or more components, it has the following characteristics (B-1) to (B) as a blend of two or more components. -2) is satisfied.
Polypropylene-based resin (B) is selected from one or more propylene homopolymers and copolymers of propylene and α-olefins having 2 to 12 carbon atoms (excluding 3 carbon atoms), preferably propylene alone. It is a polymer.
The polypropylene-based resin (B) can be appropriately selected from commercially available propylene homopolymers and propylene-α-olefin copolymers. Specifically, the trade name "Novatech PP" manufactured by Japan Polypropylene Corporation and the trade name "Wintec" are listed.

2-1) Requirement (B-1): Melt flow rate (230°C, 2.16 kg load)
The melt flow rate (230° C., 2.16 kg load) of the polypropylene resin (B) is 0.5 g/10 min or more and 25 g/10 min or less, preferably 0.5 to 15 g/10 min, more preferably 0.5 to 10 g/10 minutes. If the melt flow rate is 0.5 g/10 minutes or more, poor appearance of the film such as fish eyes is less likely to occur when combined with the polypropylene resin (A). If it is 25 g/10 minutes or less, the heat sealing temperature range is widened so that the heat sealing strength of the heat sealing film obtained by combining with the polypropylene resin (A) is 2.9 to 9.8 N / 15 mm width. easy.

2-2) Requirement (B-2): Melting peak temperature by differential scanning calorimetry (DSC) The melting peak temperature (by DSC) of the polypropylene resin (B) is 140°C or higher, preferably 150°C or higher, More preferably 155°C or higher, particularly preferably 160°C or higher. If the melting peak temperature is 140 ° C. or higher, the heat sealing temperature range in which the heat sealing strength of the heat sealing film obtained by combining with the polypropylene resin (A) is 2.9 to 9.8 N / 15 mm width. Wide and easy to take. Although the upper limit of the melting peak temperature of the polypropylene-based resin (B) is not particularly limited, it is preferably 170° C. or less, for example.
In the present invention, the difference between the melting peak temperature of the polypropylene resin (A) and the melting peak temperature of the polypropylene resin (B) is 20° C. or more from the viewpoint of ensuring a wide sealing temperature range for the obtained film, Preferably, it is 25°C or higher.

The heat seal strength of the heat seal film made of the resin composition of the present invention is 2.9 to 9.8 N / 15 mm width The reason why it is easy to take a wide heat seal temperature range is not well understood, but the polypropylene resin If (A) is a multi-stage polymer and the difference in melting peak temperature between the polypropylene resin (B) is 20°C or more, the microscopic mixed state of the polypropylene resin (A) and the polypropylene resin (B) is optimized, the polypropylene resin (B) acts to suppress the increase in seal strength, and the resulting film has a wide weak seal temperature range.

The resin composition of the present invention contains 30 to 95% by weight of polypropylene resin (A) and 5 to 70% by weight of polypropylene resin (B).
The content of the polypropylene resin (A) is 30 to 95% by weight, preferably 40 to 95% by weight, more preferably 45 to 90% by weight, still more preferably 50 to 85% by weight. The content of the polypropylene resin (B) is 5 to 70% by weight, preferably 5 to 60% by weight, more preferably 10 to 55% by weight, still more preferably 15 to 50% by weight.
When the content of the polypropylene resin (A) and the polypropylene resin (B) is within the above range, the heat sealing temperature at which the heat sealing strength of the resulting heat sealing film is 2.9 to 9.8 N/15 mm width. Wide width is easy to obtain. Moreover, it is possible to prevent the temperature at which the heat seal strength becomes 29.4 N/15 mm width or more from becoming too high. Therefore, a strong seal can be formed at a practical heat sealing temperature of 160° C. or less.

Further, in the polypropylene resin (A), the MFR of the second component calculated from the ratio of the MFR of the entire polypropylene resin (A) to the MFR of the first component is 50 g/10 min or more, 10000 g/ It is 10 minutes or less, preferably 75 g/10 minutes or more and 5000 g/10 minutes or less, more preferably 500 g/10 minutes or more and 1000 g/10 minutes or less. If the melt flow rate of the second component is 50 g/10 minutes or more, the weak seal forming temperature range of the obtained film tends to widen by combining with the polypropylene resin (B). Also, if it is 10000 g/10 minutes or less, molding stability during molding of a heat-sealing film is good.

About MFR Calculation Method As for the MFR of a multistage polymer, it is often possible to measure only the MFR of the entire multistage polymer and the MFR of either the first component or the second component. The method for calculating the unknown MFR of the first component or the second component is described in 1. of Examples described later. As described in the measurement method, for example, the method disclosed in JP-A-2001-72730 can be mentioned, and according to the formula 2 of the publication, the MFR of either the first component or the second component is unknown. Even in this case, if the MFR of the entire multistage polymer, the MFR of either the first component or the second component, and the weight ratio of the first component to the second component are known, the unknown MFR can be estimated.

3. Elastomer (C)
In addition, the resin composition of the present invention optionally contains 0 to 100 parts by weight of elastomer (C) with respect to a total of 100 parts by weight of polypropylene resin (A) and polypropylene resin (B).
The elastomer (C) is contained when the film made of the heat-sealing resin composition used in the present invention requires impact resistance or when further adjustment of heat-sealing properties is required.
The content of the elastomer (C) is 0 parts by weight or more and 100 parts by weight or less, preferably 0 parts by weight or more and 70 parts by weight, based on a total of 100 parts by weight of the polypropylene resin (A) and the polypropylene resin (B). Below, it is more preferably 0 to 60 parts by weight, still more preferably 10 to 60 parts by weight, and particularly preferably 10 to 50 parts by weight.
If the content of the elastomer (C) is 100 parts by weight or less, the resulting heat-sealing film is not heat-sealed during sterilization at a high temperature of 121° C. for 30 minutes, for example. In addition, it is easy to achieve a heat seal strength of 29.4 N/15 mm width or more when heat-sealed at a high temperature.

The elastomer (C) is not particularly limited as long as it can impart impact resistance, but is preferably an ethylene-α-olefin copolymer, a styrene elastomer, a propylene-α-olefin copolymer or a mixture thereof.
The ethylene-α-olefin copolymer is a copolymer containing ethylene as a main component, and is a copolymer obtained by copolymerizing ethylene and an α-olefin preferably having 3 to 20 carbon atoms, Preferred α-olefins include those having 3 to 20 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 1-octene and 1-heptene.
Examples of commercially available products include Japan Polyethylene Co., Ltd. trade name "Kernel" series, Mitsui Chemicals Co., Ltd. trade name "Tafmer A" series and "Toughmer MY" series, and Dow Co., Ltd. trade name "AFFINITY". series, the "ENGAGE" series, and the "EXACT" series (trade name) manufactured by Exxon-Mobil.
The density of the ethylene-α-olefin copolymer is preferably 0.86-0.91 g/cm ³ , more preferably 0.87-0.90 g/cm ³ .
The melt index (190° C., 2.16 kg load) of the ethylene-α-olefin copolymer is preferably 0.5 to 10 g/10 minutes.

The propylene-α-olefin copolymer is a copolymer containing propylene as a main component, and is obtained by copolymerizing propylene and an α-olefin preferably having 2 to 20 carbon atoms (excluding 3). The coalesced α-olefin preferably has 2 to 20 carbon atoms (excluding 3), such as ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-heptene, and the like. I can give an example.
Examples of commercially available products include Exxon-Mobil's product name "Vistamaxx" series and the like.

As the styrene-based elastomer, it is possible to appropriately select and use it from commercially available ones. As a product name, Asahi Kasei Chemicals Co., Ltd. under the trade name of "Tuftech", Kuraray Co., Ltd. under the trade name of "Septon" as a hydrogenated styrene-isoprene block copolymer, styrene-vinylized poly It is sold by Kuraray Co., Ltd. as a hydrogenated product of isoprene block copolymer under the trade name of "Hybler", and as a hydrogenated product of styrene-butadiene random copolymer under the trade name of "Dynaron" by JSR Corporation. Therefore, it may be selected and used as appropriate from these product groups.

4. Other Components Various other components such as other resins or additives can be added to the heat-sealing resin composition used in the present invention to the extent that the object of the present invention is not impaired.
Additives such as antioxidants that can be added to polypropylene-based resins can be appropriately added to the heat-sealing resin composition used in the present invention as long as the effects of the present invention are not hindered.
Specifically, 2,6-di-t-butyl-p-cresol (BHT), tetrakis [methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane (BASF Japan Co., Ltd. trade name “IRGANOX 1010”) and n-octadecyl-3-(4-hydroxy-3,5-di-t-butylphenyl) propionate (BASF Japan Co., Ltd. trade name “IRGANOX 1076”). Phosphite stabilizers such as phenolic stabilizers, bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite and tris(2,4-di-t-butylphenyl)phosphite Lubricants represented by stabilizers, higher fatty acid amides such as oleic acid amide and erucic acid amide, higher fatty acid esters, silicone oils, glycerin esters, sorbitan acid esters, and polyethylene glycol esters of fatty acids with 8 to 22 carbon atoms. antistatic agent, sorbitol nucleating agent (for example, trade name “Gelol MD” manufactured by Shin Nippon Rika Co., Ltd.), aromatic phosphate esters (for example, trade name “ADEKA STAB NA-21” manufactured by ADEKA Co., Ltd.) and "ADEKA STAB NA-11"), Milliken's product name "Millad" series, Milliken's product name "Hyperform" series, New Japan Chemical Co., Ltd. product name "NJester NU-100", talc, high density Nucleating agents such as polyethylene, anti-blocking agents such as silica, calcium carbonate and talc, molecular weight modifiers and cross-linking aids such as organic peroxides, and higher fatty acid metal salts such as calcium stearate. Neutralizing agents represented by hydrotalcites, light stabilizers, ultraviolet absorbers, metal deactivators, peroxides, fillers, antibacterial antifungal agents, antibacterial agents, antibacterial agents, fluorescent brighteners, Anti-fogging agents, flame retardants, colorants, pigments, natural oils, synthetic oils, waxes, and organic or inorganic flame retardants may be added depending on the application, and the blending amount is an appropriate amount. .

[Method for producing resin composition]
The heat-sealing resin composition used in the present invention comprises the above polypropylene resin (A), the above polypropylene resin (B) and, if necessary, the elastomer (C), additives and/or other resins, a Henschel mixer ( (trade name), V blender, ribbon blender, tumbler blender or the like, followed by kneading with a kneader such as a single-screw extruder, a multi-screw extruder, a kneader, or a Banbury mixer. Further, as another form, the above polypropylene resin (A), the above polypropylene resin (B) and, if necessary, the elastomer (C) are individually mixed together with additives and/or other resins, etc. Henschel mixer (trade name) ), a V blender, a ribbon blender, a tumbler blender, etc., then kneaded and pelletized with a kneader such as a single screw extruder, a multi-screw extruder, a kneader, a Banbury mixer, etc. Henschel mixer (trade name), V blender , a ribbon blender, a tumbler blender, or the like. As optional components, when using elastomers and other additives, they can also be added when obtaining the pellet mixture. Alternatively, a mixture obtained by blending with a Henschel mixer (trade name), a V blender, a ribbon blender, a tumbler blender, or the like can be used as it is as a pellet mixture.

[the film]
The heat-sealing resin composition used in the present invention is suitable for a heat-sealing film containing one or more layers of such a resin composition as a heat-sealing layer, particularly a heat-sealing film that achieves both low heat-sealing strength and high heat-sealing strength. can be used.
The film obtained by the production method of the present invention is a film comprising one or more layers including at least a heat-sealing layer, and the heat-sealing layer is made of the above-described heat-sealing resin composition used in the present invention.
The film may be a single layer or multiple layers, but from the viewpoint of operability during heat sealing, it is preferably a laminate, that is, a multilayer film.

Moreover, the film may be an unstretched film or a film stretched in one or more directions. Examples of stretched films include films stretched sequentially or simultaneously in the flow direction and/or the direction perpendicular to the flow of the film. The thickness of the film is not particularly limited, but in the case of a single-layer film, one having a thickness of about 10 to 500 μm is suitably used as the sealant. In the case of a multilayer film, the thickness of the entire multilayer film is about 10-500 μm, and the heat seal layer of the present invention preferably has a thickness of about 5-100 μm, more preferably 10-60 μm, and still more preferably about 10-50 μm.

As the multilayer film, a two-layer film having a heat-sealing layer made of the heat-sealing resin composition used in the present invention and an outer layer adjacent thereto, and a heat-sealing layer made of the heat-sealing resin composition used in the present invention. , an intermediate layer adjacent thereto, and a three-layer film having an outer layer adjacent to the intermediate layer, a heat-sealing layer made of the heat-sealing resin composition used in the present invention, an adhesive layer adjacent thereto, and an adhesive layer adjacent to A five-layer film having a barrier layer, an adhesive layer adjacent to the barrier layer, and an outer layer adjacent to the adhesive layer, etc., but not limited to these, the heat-sealing resin composition used in the present invention is used in the heat-sealing layer. Any configuration can be used as long as it is used as

[Film manufacturing method]
The heat-sealing film obtained by the production method of the present invention is a single-layer film or multilayer film produced by cooling and solidifying a heat-sealing resin composition using a cooling roll at 30 ° C. or less in a T-die molding machine. is.
Methods for producing a multilayer film include a coextrusion method, an extrusion lamination method, a dry lamination method, and the like, and the coextrusion method is preferable from the viewpoint of economy.

In the present invention, the film is produced by cooling and solidifying using a cooling roll at 30° C. or lower in a T-die molding machine. Mass production is possible by cooling and solidifying at a cooling roll temperature of 30°C or less with a T-die molding machine, and a weak seal strength of 2.9 to 9.8 N/15 mm width is formed in a wide temperature range. Therefore, it is suitable for multi-chamber packaging bags, lid materials, and the like.
The chill roll temperature is 30° C. or lower, preferably 25° C. or lower, more preferably 20° C. or lower. When the cooling roll temperature is 30° C. or less, it is easy to obtain a wide heat sealing temperature range in which the heat sealing strength becomes 2.9 to 9.8 N/15 mm width. By setting the cooling temperature to 30° C. or lower, the crystalline state of the heat seal layer is optimized, which acts to suppress fusion bonding, and the obtained film has a wide weak sealing temperature range.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited by these as long as it does not deviate from the gist of the invention. Methods for measuring various physical property values and materials used in Examples are as follows.
1. Measurement method (1) MFR (unit: g / 10 minutes): JIS K-7210: 1999 Annex A Table 1, according to condition M, test temperature: 230 ° C., nominal load: 2.16 kg, die shape: diameter 2 Measurements were made under the conditions of 0.095 mm and a length of 8.000 mm. Further, in the polypropylene-based resin (A), the MFR of the second component calculated from the MFR of the entire polypropylene-based resin (A) and the MFR of the first component is the formula disclosed in JP-A-2001-72730. 2, it is obtained by the following formula.
logC = alogA + blogB
A: MFR of the first component, a: weight ratio of the first component in the polypropylene resin (A) B: MFR of the second component, b: the second component in the polypropylene resin (A) Weight ratio of components C: MFR of entire polypropylene resin (A)
However, a+b=1.
(2) Melting peak temperature: Using a differential scanning calorimeter (DSC; TA Instruments, Model Q2000), a sample amount of 5.0 mg was taken, held at 200°C for 5 minutes, and then heated to 40°C at 10°C/min. Crystallization was performed at a cooling speed, and melting peak temperature was measured when the temperature was increased at a temperature rising speed of 10°C/min.
(3) Ethylene content of polypropylene resin Based on the ethylene content of a standard sample obtained by the ethylene content measurement method by ¹³ C-NMR described in JP-A-2003-73426, the infrared absorption spectrum A relational expression (formula [1] below) between the peak height I [absorption] in the range of 700 to 760 cm ⁻¹ and the ethylene content E (A) [% by weight] was calculated and used.
A sheet of 0.5 mm was produced from 5 g of polypropylene resin by press molding at 190° C., and the infrared absorption spectrum of this sheet was measured. D [mm] in the following formula [1] is the thickness of the sheet, and a numerical value accurately measured to the nearest 10 μm was used.
Formula [1] Ethylene content (% by weight) = 5 x I/D + 0.0613
(4) Heat seal strength (unit: N/15 mm width): Using a heat seal bar of 5 mm × 200 mm, the obtained film was heat-sealed between 110 ° C. and 160 ° C. so that the heat seal layers were heat-sealed. It was sealed perpendicularly to the direction of melt extrusion (MD) under heat sealing conditions of 0.34 MPa pressure and 5 seconds in increments of °C. Next, a sample was cut so that the heat-sealed portion had a width of 15 mm, and was separated using a tensile tester at a tensile speed of 500 mm/min to determine the heat-seal strength. Plot the relationship between the heat seal temperature and the maximum heat seal strength, determine the slope from the resulting curve, weak seal start temperature (heat seal strength reaches 2.9 N / 15 mm width), weak seal end temperature (heat The temperature at which the seal strength reaches 9.8 N/15 mm width) and the strong seal initiation temperature (the temperature at which the heat seal strength reaches 29.4 N/15 mm width) were determined. If the heat seal strength is 2.9 to 9.8 N / 15 mm width, the resin film or sheet in the partition inside the container is difficult to peel off during manufacturing and transportation, and during use (during mixing) It can be said that the heat seal strength is sufficient if it can be easily peeled off by hand or with a tool, and if it is 29.4 N/15 mm width or more. Further, it can be said that a weak seal strength can be easily formed when the weak seal temperature range is 10° C. or higher.

2. Material used PP1 (propylene-α-olefin random copolymer polymerized with a metallocene catalyst): A multistage polymer obtained in the following <Production example of PP1> was used (melting peak temperature: 122°C, MFR: 5 .3 g/10 min).
PP2 (propylene-α-olefin random copolymer polymerized with a metallocene catalyst): trade name Wintech WFX6 manufactured by Japan Polypropylene Corporation (melting peak temperature: 125°C, MFR: 2 g/10 minutes, not a multistage polymer ).
PP3 (propylene-α-olefin random copolymer polymerized with a metallocene catalyst): trade name Wintec WSX03 manufactured by Japan Polypropylene Corporation (melting peak temperature: 125°C, MFR: 25 g/10 minutes, not a multi-stage polymer ).
PP4 (propylene homopolymer polymerized with Ziegler catalyst): Novatec PP FY4 (trade name) manufactured by Japan Polypropylene Corporation (melting peak temperature: 160°C, MFR: 5 g/10 minutes).
PP5 (propylene homopolymer polymerized with Ziegler catalyst): Novatec PP FY6 (trade name) manufactured by Japan Polypropylene Corporation (melting peak temperature: 160°C, MFR: 2.4 g/10 minutes).

<Production example of PP1>
(i) Preparation of prepolymerization catalyst (chemical treatment of silicate)
3.75 liters of distilled water and then 2.5 kg of concentrated sulfuric acid (96%) were slowly added to a 10 liter glass separable flask equipped with a stirring blade. At 50° C., 1 kg of montmorillonite (trade name “Benclay SL” manufactured by Mizusawa Chemical Industry Co., Ltd.; average particle size = 25 μm, particle size distribution = 10 to 60 μm) was dispersed, and the temperature was raised to 90° C. for 6.5 hours. The temperature was maintained.
After cooling to 50° C., the slurry was filtered under reduced pressure to collect a cake. The cake was reslurried by adding 7 liters of distilled water and filtered. This washing operation was carried out until the pH of the washing liquid (filtrate) exceeded 3.5. The collected cake was dried overnight at 110° C. under a nitrogen atmosphere. The weight after drying was 707 g.
(Drying of silicate)
The previously chemically treated silicate was dried using a kiln dryer. Specifications and drying conditions are as follows.
Rotating cylinder: Cylindrical, inner diameter 50 mm, heating zone 550 mm (electric furnace)
Rotation speed with scraping blade: 2 rpm Tilt angle: 20/520
Feed rate of silicate: 2.5 g/min Gas flow rate: Nitrogen 96 l/h Countercurrent drying temperature: 200°C (powder temperature)

(Preparation of catalyst)
A 16 liter internal volume autoclave equipped with stirring and temperature controls was thoroughly flushed with nitrogen. 200 g of dry silicate was introduced, 1160 ml of mixed heptane and 840 ml of triethylaluminum in heptane (0.60 M) were added and stirred at room temperature. After 1 hour, the silicate slurry was adjusted to 2,000 ml by washing with mixed heptane. Next, 9.6 ml of a heptane solution (0.71 M) of triisobutylaluminum was added to the previously prepared silicate slurry and reacted at 25° C. for 1 hour. In parallel, 2,177 mg (3 mmol) of (r)-dichloro[1,1′-dimethylsilylenebis{2-methyl-4-(4-chlorophenyl)-4H-azulenyl}]zirconium and 870 ml of heptane mixed with Add 33.1 ml of a solution of isobutylaluminum in heptane (0.71 M) and react for 1 hour at room temperature. Add the mixture to the silicate slurry, stir for 1 hour, and adjust to 5,000 ml by adding mixed heptanes. bottom.

(prepolymerization/washing)
Subsequently, the temperature in the tank was raised to 40° C., and when the temperature was stabilized, propylene was supplied at a rate of 100 g/hour to maintain the temperature. After 4 hours the propylene feed was stopped and maintained for an additional 2 hours.
After the prepolymerization was completed, the residual monomer was purged, the stirring was stopped, and the mixture was allowed to stand still for about 10 minutes, after which 2,400 ml of the supernatant was decanted. Subsequently, 9.5 ml of a heptane solution of triisobutylaluminum (0.71 M) and 5,600 ml of mixed heptane were added, stirred at 40° C. for 30 minutes, allowed to stand for 10 minutes, and then 5,600 ml of the supernatant was removed. Furthermore, this operation was repeated 3 times. When the component analysis of the final supernatant liquid was carried out, the concentration of the organoaluminum component was 1.23 mM, and the Zr concentration was 8.6×10 ⁻⁶ g/L. ratio) was 0.018% by weight. Subsequently, after adding 170 ml of a heptane solution of triisobutylaluminum (0.71 M), drying was performed under reduced pressure at 45°C.
By this operation, a prepolymerized catalyst containing 2.0 g of polypropylene per 1 g of catalyst was obtained.
Using this prepolymerized catalyst, a propylene-based resin composition was produced according to the following procedure.

(ii) First Polymerization Step A horizontal reactor (L/D=4.3, internal volume: 100 liters) having stirring blades was sufficiently dried, and the inside was sufficiently replaced with nitrogen gas. In the presence of a polypropylene powder bed, while stirring at a rotation speed of 33 rpm, 0.71 g/hr of the prepolymerized catalyst prepared by the above method (as a solid catalyst amount excluding the prepolymerized powder) was added to the upstream part of the reactor. Triisobutylaluminum was continuously supplied at 30 mmol/hr. The temperature is 53° C. on the upstream side and 54° C. on the downstream side of the reactor, and the pressure is kept at 2.1 MPaG. Gas phase polymerization was performed by continuously circulating the monomer mixed gas in the reactor so that the concentration was 70 molppm. The polymer powder produced by the reaction was continuously withdrawn from the downstream portion of the reactor so that the amount of powder bed in the reactor was constant. At this time, the amount of polymer withdrawn when a steady state was reached was 7.6 kg/hr.
The propylene-ethylene random copolymer obtained in the first polymerization step was analyzed and found to have an MFR of 1.5 g/10 minutes, a melting peak temperature of 121.5° C. and an ethylene content of 3.3 wt %.

(iii) Second Polymerization Step The propylene-ethylene copolymer extracted from the first polymerization step was continuously supplied to a horizontal reactor (L/D=4.3, internal volume: 100 liters) having a stirring blade. While stirring at a rotation speed of 25 rpm, the temperature of the reactor is kept at 65° C. and the pressure is kept at 1.9 MPaG. As described above, the gas phase polymerization was performed by continuously circulating the monomer mixed gas in the reactor. The polymer powder produced by the reaction was continuously withdrawn from the downstream portion of the reactor so that the amount of powder bed in the reactor was constant. At this time, oxygen was supplied as an activity inhibitor so that the amount of polymer withdrawn was 10.0 kg/hr, and the amount of polymerization reaction in the second polymerization step was controlled. The activity was 14 kg/g-catalyst.
1000 ppm by weight of Irganox 1010 and 1000 ppm by weight of Irgaphos 168 as antioxidants were added to the obtained powdered PP1, mixed with a Henschel mixer (trade name), and then granulated with a single-screw granulator of Φ30 mm to 200 C. to obtain pellet-like PP1.
The ratio of the first component calculated from the following formula was 76% by weight, and the MFR of the second component calculated from the MFR formula was 280 g/10 minutes.
Proportion of the first component = Amount extracted from the first polymerization step / Amount extracted from the second polymerization step

(Example 1)
PP5 is introduced as a resin for the intermediate layer with a diameter of φ30 mm and the surface layer of the non-heat-sealed surface with a diameter of φ18 mm in a three-kind, three-layer T-die molding machine. PP1 and PP4 at a weight ratio of 85% to 15% were mixed by shaking the bag up and down and left and right by hand to fully stir the contents, and the extruder temperature was 200 ° C. , Melt extrusion from a T die with a die width of 150 mm and a lip width of 1 mm at a die temperature of 220 ° C., cooled and solidified with a cooling roll adjusted to 10 ° C., and a film with a thickness of 100 µm at a speed of 7 m per minute Surface layer: intermediate The layer:heat seal layer thickness ratio was made to be 1:7:2. Table 1 shows the evaluation results of the films. It has a wide temperature range in which a heat seal strength of 2.9 to 9.8 N/15 mm width can be formed, and weak seal formation is easy. Moreover, it is possible to form a heat seal strength of 29.4 N/15 mm width at a practical heat seal temperature of 160°C or less.

(Comparative example 1)
A film was obtained in the same manner as in Example 1, except that PP1 was replaced with PP2 in the resin used for the heat seal layer of Example 1. Table 1 shows the evaluation results of the obtained film. Compared to the examples, the temperature range in which a heat seal strength of 2.9 to 9.8 N/15 mm width can be formed is narrower, making it difficult to form a weak seal.

(Comparative example 2)
A film was obtained in the same manner as in Comparative Example 1 except that the cooling roll temperature in Comparative Example 1 was changed to 30°C. Table 1 shows the evaluation results of the obtained film. Compared to the examples, the temperature range in which a heat seal strength of 2.9 to 9.8 N/15 mm width can be formed is narrower, making it difficult to form a weak seal.

(Comparative Example 3)
A film was obtained in the same manner as in Example 1, except that PP2 was replaced with PP3 in the resin used for the heat seal layer of Comparative Example 2. Table 1 shows the evaluation results of the obtained film. Compared to the examples, the temperature range in which a heat seal strength of 2.9 to 9.8 N/15 mm width can be formed is narrower, making it difficult to form a weak seal.

(Comparative Example 4)
A film was obtained in the same manner as in Example 1, except that the temperature of the cooling roll in Example 1 was changed to 50°C. Table 1 shows the evaluation results of the obtained film. Compared to the examples, the temperature range in which a heat seal strength of 2.9 to 9.8 N/15 mm width can be formed is narrower, making it difficult to form a weak seal.

(Comparative Example 5)
A film was obtained in the same manner as in Comparative Example 1, except that the cooling roll temperature in Comparative Example 1 was changed to 50°C. Table 1 shows the evaluation results of the obtained film. Compared to the examples, the temperature range in which a heat seal strength of 2.9 to 9.8 N/15 mm width can be formed is narrower, making it difficult to form a weak seal.

(Comparative Example 6)
A film was obtained in the same manner as in Comparative Example 3, except that the cooling roll temperature was changed to 50°C. Table 1 shows the evaluation results of the obtained film. Compared to the examples, the temperature range in which a heat seal strength of 2.9 to 9.8 N/15 mm width can be formed is narrower, making it difficult to form a weak seal.

Claims (4)

A method for producing a film having a heat seal layer as at least one layer, the heat seal layer comprising 30 to 95% by weight of the following polypropylene resin (A) component and 5 to 70% by weight of the following polypropylene resin (B) component, With respect to a total of 100 parts by weight of the polypropylene resin (A) and the polypropylene resin (B), optionally containing 0 parts by weight or more and 100 parts by weight or less of the elastomer (C), the polypropylene resin (A) and the polypropylene resin ( B) A method for producing a heat-sealing film by cooling and solidifying a resin composition having a melting peak temperature difference of 20° C. or more in a T-die molding machine using a cooling roll of 30° C. or less.
Component (A): A multi-stage polymer satisfying the following requirements (A-1) and (A-2), wherein the first component of the multi-stage polymer is (a-1) to (a-3) Polypropylene resin that meets the requirements.
(A-1) Melt flow rate (MFR) (JIS K7210, temperature 230 ° C., 2.16 kg load) is 1 g / 10 minutes or more and 50 g / 10 minutes or less (A-2) Melting peak temperature by DSC 110°C or more and less than 140°C.
(a-1) Melt flow rate (MFR) (JIS K7210, temperature 230 ° C., 2.16 kg load) is 0.1 g / 10 minutes or more and 10 g / 10 minutes or less (a-2) Melting peak by DSC The temperature should be 110°C or higher and less than 140°C.
(a-3) The first component is 5 parts by weight or more and 95 parts by weight or less per 100 parts by weight of the polypropylene resin (A).
Component (B): Polypropylene resin (B-1) that satisfies the requirements of (B-1) and (B-2) below Melt flow rate (MFR) (JIS K7210, 230°C, 2.16 kg load) is 0 .5 g/10 minutes or more and 25 g/10 minutes or less.
(B-2) The melting peak temperature measured by DSC is 140° C. or higher. The polypropylene resin (A) is composed of a first component and a second component, and in the polypropylene resin (A), it is calculated from the MFR of the entire polypropylene resin (A) and the MFR of the first component. 2. The method for producing a heat-sealable film according to claim 1, wherein the second component has an MFR of 50 g/10 minutes or more and 10000 g/10 minutes or less. The method for producing a heat-sealable film according to claim 1 or 2, wherein the polypropylene-based resin (A) is a metallocene-based polypropylene-based resin. The heat-sealing material according to any one of claims 1 to 3, wherein the elastomer (C) is an ethylene-α-olefin copolymer and/or a styrene elastomer and/or a propylene-α-olefin copolymer. Film production method.