WO2023062950A1

WO2023062950A1 - Resin composition for polypropylene film formation, polypropylene film, and multilayer body

Info

Publication number: WO2023062950A1
Application number: PCT/JP2022/032086
Authority: WO
Inventors: 浩介高柳; 竜典小野; 雄太桶屋
Original assignee: 凸版印刷株式会社
Priority date: 2021-10-15
Filing date: 2022-08-25
Publication date: 2023-04-20

Abstract

The present invention relates to a resin composition for polypropylene film formation including: a polypropylene resin; and an antioxidant including a first antioxidant having a primary antioxidant function, and a hydroxylamine-based second antioxidant having a primary antioxidant function and a secondary antioxidant function.

Description

POLYPROPYLENE FILM-FORMING RESIN COMPOSITION, POLYPROPYLENE FILM, AND LAMINATE

The present invention relates to a polypropylene film-forming resin composition, a polypropylene film, and a laminate.

Films made from polypropylene resin have excellent transparency, gloss, heat resistance, etc., and are used in various fields such as packaging and industrial applications. In addition, for the purpose of improving moisture resistance and oxygen barrier properties, films made of polyethylene, polyethylene terephthalate, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, etc., aluminum foil, etc. are added to the polypropylene film. Various laminated bodies are also known.

Generally, when forming a film using polypropylene resin as a raw material, various additives such as antioxidants, lubricants, antiblocking agents, and antistatic agents are used.

Among the above additives, antioxidants reduce the molecular weight of polypropylene due to the effects of the heat of the extruder when forming a film, the shearing force of the screw of the extruder, or the catalyst residue contained in the polypropylene resin. It is added for the purpose of preventing oxidative deterioration from progressing.

It is generally known that oxidative deterioration of polypropylene resin progresses through the following cycle.
(1) A polymer (RH) generates carbon radicals (R.) by the action of heat or light.
(2) R· reacts with oxygen to generate a peroxy radical (ROO·).
(3) ROO· extracts H· from surrounding RH to form hydroperoxide (ROOH), and at the same time, regenerates R·.

In order to prevent the progress of the cycle of oxidation deterioration as described above, a primary antioxidant that captures peroxy radicals (ROO), such as a hindered phenol-based antioxidant, a phosphorus-based antioxidant, and a sulfur-based antioxidant It is common to add to the polypropylene resin together with a secondary antioxidant that decomposes hydroperoxide (ROOH) such as an antioxidant.

Phosphorus-based antioxidants, which are secondary antioxidants, undergo a hydrolysis reaction to generate phosphorous acid when stored alone before film formation and during the storage process after film formation. It has been known. When phosphorous acid is produced, the antioxidation performance is lowered, and at the same time, it causes damage such as fouling of equipment such as an extruder and a take-up machine.

For this reason, various phosphate-based antioxidants that are resistant to hydrolysis have been devised. For example, Irgafos168 (main component: tris (2,4-di-t-butylphenyl) phosphite) manufactured by BASF Japan Co., Ltd. shown in formula (1) has three ortho positions substituted with t-butyl groups. It is phenol, and strengthening the space hindrance of the substituent at the ortho position of phenol makes it difficult for the phosphorus atom to come into contact with water molecules, preventing the progress of the hydrolysis reaction.

For example, Patent Document 1 discloses the use of the above phosphite-based antioxidant in combination with a phenol-based antioxidant, a lactone-based antioxidant, or the like.

JP 2007-126644 A

By the way, the above-mentioned phosphite-based antioxidants can prevent the progress of the hydrolysis reaction, but at the same time, the affinity for oxygen atoms and the performance as an antioxidant may be reduced, and a sufficient antioxidant effect can be obtained. need to increase the amount added.

However, if the amount of the antioxidant added is increased, the antioxidant and its decomposition products may appear on the film surface during film formation, during post-processing such as lamination after film formation, or during storage after film formation. may bleed out, resulting in contamination of equipment such as an extruder and a take-up machine, troubles in subsequent processes, and the like.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a resin composition for forming a polypropylene film that is excellent in processing stability during film formation and long-term thermal stability after film formation. Another object of the present invention is to provide a polypropylene film obtained using the resin composition, and a laminate comprising the polypropylene film.

The resin composition for forming a polypropylene film according to one aspect of the present invention includes a polypropylene resin, a first antioxidant having a primary antioxidant function, and a hydroxylamine-based antioxidant having a primary antioxidant function and a secondary antioxidant function. and an antioxidant comprising a second antioxidant.

The above resin composition comprises a first antioxidant having a function of scavenging peroxy radicals (ROO.), a function of scavenging peroxy radicals (ROO.), and a hydroperoxide It also contains a second antioxidant that also has the function of decomposing oxide (ROOH). By using these antioxidants together, it is possible to keep the amount of antioxidants added to a lower level than conventionally, thereby suppressing the oxidation deterioration of polypropylene resin due to the heat of the extruder during film formation. (processing stability), and oxidative deterioration suppressing property (long-term thermal stability) of the polypropylene resin during storage after film formation can be obtained.

In one aspect of the resin composition, the first antioxidant may be a hindered phenol-based antioxidant.

In one aspect of the resin composition, the second antioxidant may be bis-octadecylhydroxylamine.

In one aspect of the resin composition, the content of the first antioxidant may be 300 ppm by mass or more, and the content of the second antioxidant is 300 mass ppm, based on the total amount of the polypropylene resin and the antioxidant. It may be mass ppm or more, and the total content of the first antioxidant and the second antioxidant may be 2500 mass ppm or less.

A polypropylene film according to one aspect of the present invention is formed from the above resin composition.

In one aspect of the polypropylene film, the melt flow rate (JIS K6921-2 compliant, temperature 230°C, load 2.16 kg) may be 20.0 g/10 min or less.

A laminate according to one aspect of the present invention includes the above film.

According to the present invention, it is possible to provide a polypropylene film-forming resin composition that is excellent in processing stability during film formation and long-term thermal stability after film formation. Moreover, according to this invention, the polypropylene film obtained using the said resin composition, and the laminated body provided with the said polypropylene film can be provided.

Preferred embodiments of the present invention will be described below, but the present invention is not limited only to the following embodiments. Various aspects illustrated in the embodiments may be combined as appropriate.

<Resin composition for forming polypropylene film>
The polypropylene film-forming resin composition comprises a polypropylene resin, a first antioxidant having a primary antioxidant function, and a hydroxylamine-based second antioxidant having a primary antioxidant function and a secondary antioxidant function. and an antioxidant. The antioxidant may consist of a first antioxidant and a second antioxidant.

(polypropylene resin)
Polypropylene resins include homopolymers that are polymers of propylene only (propylene homopolymers), random copolymers that are copolymers of propylene and ethylene (propylene-ethylene random copolymers), and ethylene-propylene in homopolymers. Examples include block copolymers having a structure in which polymers are scattered (propylene/ethylene block copolymers) and the like, and any polymer can enjoy the effects of the antioxidant. Moreover, the stereoregularity of the polypropylene resin may be isotactic, syndiotactic, or atactic. Any known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst can be selected for the polymerization of the polypropylene resin, and any known production method may be used.

(Antioxidant)
Examples of the first antioxidant having a primary antioxidant function include antioxidants such as hindered phenols. A primary antioxidant can be referred to as an antioxidant that only functions as a primary antioxidant. The first antioxidant has a function of scavenging peroxy radicals (ROO.) in the oxidative deterioration cycle of the polypropylene resin.

Hindered phenol antioxidants include 2,6-di-tert-butyl-4-methylphenol, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)stearyl propionate, tetrakis [ 3-(3,5-Di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol, etc. may be appropriately selected and used.

As the first antioxidant, it is preferable to use a hindered phenol-based antioxidant. Hindered phenol-based antioxidants are known to function as antioxidants in a wide range of temperatures from low temperature (about 0°C) to high temperature (about 300°C), and have good processing stability. and long-term thermal stability.

A hydroxylamine-based antioxidant is used as the second antioxidant that has (combines) primary antioxidant function and secondary antioxidant function. The second antioxidant has both the function of trapping peroxy radicals (ROO.) and the function of decomposing hydroperoxide (ROOH) in the oxidative degradation cycle of polypropylene resin. By using such a second antioxidant together with the first antioxidant, the amount of the antioxidant to be added can be reduced as a whole compared to conventional methods.

As the hydroxylamine-based antioxidant, it is preferable to use bis-octadecylhydroxylamine. By using bis-octadecylhydroxylamine, in addition to the function of preventing oxidative deterioration of polypropylene resin, discoloration of the film and decomposition of polypropylene resin are prevented when the film formed is irradiated with radiation such as gamma rays or electron beams. You can give it the ability to prevent.

Based on the total amount of polypropylene resin and antioxidant (first antioxidant and second antioxidant), the content of the first antioxidant is preferably 300 ppm by mass or more, and the second oxidation The content of the inhibitor is preferably 300 ppm by mass or more. Thereby, the effect of preventing oxidative deterioration of the polypropylene resin can be easily obtained. From this point of view, the content of the first antioxidant is more preferably 400 mass ppm or more, or 500 mass ppm or more, and the content of the second antioxidant is 400 mass ppm or more or 500 mass ppm or more. It is more preferable to have Moreover, based on the total amount of the polypropylene resin and the antioxidant, the total content of the first antioxidant and the second antioxidant is preferably 2500 ppm by mass or less. As a result, bleeding out of the antioxidant and its decomposition products onto the surface of the film, contamination of equipment such as an extruder and a take-up machine, troubles in subsequent processes, and the like can be easily suppressed. From this point of view, the total content of the first antioxidant and the second antioxidant is more preferably 2300 ppm by mass or less, or 2000 ppm by mass or less.

The mass ratio of the content of the second antioxidant to the content of the first antioxidant (content of the second antioxidant / content of the first antioxidant) is 0.5 to 2 and more preferably 0.75 to 1.5 or 0.9 to 1.1. Thereby, the effect of preventing oxidative deterioration of the polypropylene resin can be easily obtained.

(other ingredients)
Other components of the resin composition include a neutralizing agent for neutralizing catalyst residues, a nucleating agent for crystallization of polypropylene, a lubricant for reducing the coefficient of friction on the film surface, and a film winding agent. Ingredients (additives) such as anti-blocking agents that prevent blocking when stored in a removed state, anti-static agents that prevent foreign matter from adhering to the surface of the film and static electricity that prevents the film from adhering to processing machines and other films agent) can be contained as appropriate depending on the actual use.

<Polypropylene film>
A polypropylene film is formed from the resin composition for forming a polypropylene film. Various methods such as heat pressing, extrusion molding, casting molding, and calender molding can be appropriately selected as the method for forming the polypropylene film. The polypropylene film may be subjected to various stretching processes such as uniaxial stretching, sequential biaxial stretching, simultaneous biaxial stretching, and multistage stretching.

The melt flow rate (JIS K6921-2 compliant, temperature 230°C, load 2.16 kg) of the polypropylene film (the polypropylene resin composition constituting the film) is preferably 20.0 g/10 min or less. This indicates that the antioxidant functions sufficiently, and the heat of the extruder during film formation tends to prevent the oxidative deterioration of the polypropylene resin from progressing. The melt flow rate is more preferably 15.0 g/10 min or less. When the melt flow rate exceeds 20.0 g/10 min, the melt viscosity of the polypropylene resin is low, the discharge rate from the T-die is unstable, and the thickness of the film tends to vary greatly. Furthermore, problems such as a decrease in the impact resistance of the formed film are likely to occur. Although the lower limit of the melt flow rate is not particularly limited, it can be 3.0 g/10 min or more when the polypropylene resin described above is used.

The type and amount of antioxidant in the polypropylene film can be specified, for example, by an elution test (a method of immersing the film in a solvent to extract additives such as antioxidants).

<Laminate>
A laminate includes the polypropylene film. The polypropylene film may be formed as a single layer film, but by using a plurality of extruders and coextrusion of the same or different types of polypropylene resins by a feed block method or a multi-manifold method, two or more layers can be formed. It may be formed as a multilayer film. That is, the laminate can comprise multiple polypropylene films of the same or different types.

A laminate can be provided with various layers known as packaging materials on one or both sides of a single-layer or multilayer polypropylene film. Examples of such layers include sealant layers, metal foil layers, vapor deposition layers (aluminum vapor deposition, alumina vapor deposition, silica vapor deposition layers, etc.), printing layers, adhesive layers, surface protective layers, and the like. These layers can be laminated by known methods such as dry lamination, heat adhesion, printing on the film surface, coating, and vapor deposition. By providing a vapor deposition layer on the polypropylene film, it can be suitably used as a film having barrier stability while suppressing the amount of antioxidant added.

<Overview of this embodiment>
[Invention 1]
polypropylene resin;
an antioxidant comprising a first antioxidant having a primary antioxidant function and a hydroxylamine-based second antioxidant having a primary antioxidant function and a secondary antioxidant function;
A resin composition for forming a polypropylene film, comprising:
[Invention 2]
The resin composition according to Invention 1, wherein the first antioxidant is a hindered phenol-based antioxidant.
[Invention 3]
The resin composition according to invention 1 or 2, wherein the second antioxidant is bis-octadecylhydroxylamine.
[Invention 4]
Based on the total amount of the polypropylene resin and the antioxidant, the content of the first antioxidant is 300 mass ppm or more, and the content of the second antioxidant is 300 mass ppm or more, The resin composition according to any one of Inventions 1 to 3, wherein the total content of the first antioxidant and the second antioxidant is 2500 ppm by mass or less.
[Invention 5]
A polypropylene film produced from the resin composition according to any one of Inventions 1 to 4.
[Invention 6]
The film according to Invention 5, which has a melt flow rate (JIS K6921-2 compliant, temperature 230°C, load 2.16 kg) of 20.0 g/10 min or less.
[Invention 7]
A laminate comprising the film according to invention 5 or 6.

Examples based on the present invention will be described below, but the present invention is not limited to the following examples.

(Example 1)
PX600N manufactured by SunAllomer Co., Ltd. was used as a raw material for the polypropylene resin. In addition, as the first antioxidant, Irganox 1010 (main component: tetrakis [3-(3,5-di-tert-butyl-4-hydroxyphenyl ) propionic acid]pentaerythritol) and bis-octadecylhydroxylamine as the second antioxidant.

To PX600N, 500 mass ppm of Irganox 1010 and 500 mass ppm of bis-octadecylhydroxylamine were added based on the total amount of polypropylene resin and antioxidant. This resin was supplied to an extruder, heated and melted, discharged from a T-die, and brought into contact with a cooling roll while applying nip pressure to form a film. The temperature of the extruder was set to 230°C for the feeding section and 250°C for the compression section, weighing section, and T-die. The film thickness was set to 60 μm.

(Examples 2-3)
A film was formed in the same manner as in Example 1, except that the amount of each antioxidant added was changed as shown in Table 1.

(Comparative example 1)
A film was formed in the same manner as in Example 1, except that no antioxidant was added.

(Comparative Examples 2-4)
A film was formed in the same manner as in Example 1, except that the amount of each antioxidant added was changed as shown in Table 1.

(Comparative Example 5)
It is a phosphorous-based antioxidant that has a secondary antioxidant function (only functions as a secondary antioxidant) by changing the amount of Irganox 1010 added to 1000 mass ppm and replacing bis-octadecylhydroxylamine. A film was formed in the same manner as in Example 1, except that 2000 mass ppm of Irgafos 168 manufactured by BASF Japan Ltd. was added. When Irganox 1010 and Irgafos 168 are used in combination, they are generally added so that the total amount is about 3000 ppm.

(Evaluation: Melt flow rate measurement)
For the film of each example, a melt indexer (FF-01) manufactured by Toyo Seiki Seisakusho Co., Ltd. was used to measure the melt flow rate (MFR) according to JIS K6921-2. The set temperature of the melt indexer was 230°C. The film of each example was cut into a size of about 5 mm square to obtain a sample. The weight of the sample was about 5 g (approximately 5±1 g). This sample was placed in a melt indexer, and the mass of the resin ejected for 30 seconds was measured while a load of 2.16 kg was applied. This measured value was multiplied by 20 to calculate the MFR value. Table 1 shows the results.

(Evaluation: film durability)
The film of each example was cut into A4 size (210 mm in the width direction×291 mm in the machine direction) and stored in a constant temperature machine (HT310) manufactured by Espec Co., Ltd. at a set temperature of 150° C. for 60 days. The durability of the film was evaluated by recording the number of days until the film of each example was oxidatively deteriorated and broken. Table 1 shows the results.

The films of the examples prepared by adding Irganox 1010, which has a primary antioxidant function, and bis-octadecylhydroxylamine, which has both a primary antioxidant function and a secondary antioxidant function, were formed without adding an antioxidant. The value of the melt flow rate was suppressed as compared with the film of Comparative Example 1, which was obtained by adding only Irganox 1010, and the films of Comparative Examples 2 and 3, which were formed by adding only Irganox 1010. Examples show that oxidative deterioration of the polypropylene resin due to the heat of the extruder progressed relatively slowly.

For the films of Examples, no film breakage was observed when the film durability was evaluated for 60 days. On the other hand, in the film of Comparative Example 4, which was formed by adding only bis-octadecylhydroxylamine, the value of the melt flow rate was kept low, but when the film durability was evaluated, it was put into a constant temperature machine. After one day, the film was found to be broken, confirming its poor durability.

In the film of Comparative Example 5, which was formed by adding Irganox 1010 having a primary antioxidant function and Irgafos 168 having a secondary antioxidant function, the value of the melt flow rate was kept low, and the film durability for 60 days was No film breaks were observed when the evaluation was performed. However, the amount of antioxidant added was larger than that of the film of the example. Due to the large amount of antioxidant added, the antioxidant and its decomposition products bleed out on the film surface, causing problems such as contamination of equipment such as extruders and take-up machines, and troubles during post-processes. There is a risk that it will occur.

The resin composition for forming a polypropylene film according to the present disclosure can suppress oxidative deterioration of the polypropylene resin during film formation and over a long period of time after film formation. The polypropylene film produced from the resin composition can be expected to be used in various fields such as flexible packaging, electronics packaging, medical/pharmaceutical packaging, toiletry products, liquid composite paper containers, and chilled/frozen food packaging. .

Claims

polypropylene resin;
an antioxidant comprising a first antioxidant having a primary antioxidant function and a hydroxylamine-based second antioxidant having a primary antioxidant function and a secondary antioxidant function;
A resin composition for forming a polypropylene film, comprising:
The resin composition according to claim 1, wherein the first antioxidant is a hindered phenol-based antioxidant.
The resin composition according to claim 1 or 2, wherein the second antioxidant is bis-octadecylhydroxylamine.
Based on the total amount of the polypropylene resin and the antioxidant, the content of the first antioxidant is 300 mass ppm or more, and the content of the second antioxidant is 300 mass ppm or more, The resin composition according to claim 1 or 2, wherein the total content of said first antioxidant and said second antioxidant is 2500 ppm by mass or less.
A polypropylene film formed from the resin composition according to claim 1 or 2.
The film according to claim 5, which has a melt flow rate (JIS K6921-2 compliant, temperature 230°C, load 2.16 kg) of 20.0 g/10 min or less.
A laminate comprising the film according to claim 5 .