JP6834851B2 - Multilayer film and packaging - Google Patents

Description

The present invention relates to a multilayer film. More specifically, the present invention relates to a multilayer film having an excellent balance between transparency and slipperiness and having excellent slipperiness even in a high humidity environment.

In general, films using polyamide resins are excellent in mechanical properties, optical properties, thermal properties, gas barrier properties, toughness, pinhole resistance, bending resistance, etc., and are used for packaging, especially food packaging. Widely used for such purposes. The packaging film is required to have excellent slipperiness in order to improve workability and processing speed during processing such as printing, vapor deposition, laminating, and bag making. However, since a film using a polyamide resin has an amide group in its structure, its slipperiness tends to deteriorate especially in a high humidity environment, and there is a problem that blocking occurs between the films. It was. As a method for improving such blocking, for example, a method of forming fine irregularities on the film surface by blending an inorganic filler with a polyamide resin to reduce the contact area is known.

The method of forming surface protrusions by adding an inorganic filler is an effective means, but if the amount of the inorganic filler added is small, sufficient slipperiness cannot be obtained, and conversely, if the amount is too large, the transparency of the film is lowered. Therefore, due to the problem that the commercial value as a packaging film is lost, a film satisfying practicality has not been obtained by the technique of adding only an inorganic filler.

Various techniques for achieving both transparency and slipperiness have been studied in the past. For example, in Patent Document 1, a technique for suppressing a decrease in transparency and improving slipperiness by surface-treating an inorganic filler is used. It is being considered. Although the method of Patent Document 1 improves the balance between transparency and slipperiness to some extent, it has not achieved a practically satisfactory level, and slipperiness under high humidity was considered as an issue at that time. There wasn't.

Furthermore, techniques that have been attempted to be improved by combining a plurality of additives have also been studied. For example, in Patent Document 2, the inorganic particles are composed of silica having an average particle size of 1 to 2 μm and silica having an average particle size of 2 to 3 μm, and have a bisamide content of 0.1 to 0.3 consisting of a fatty acid having 20 or more carbon atoms. A biaxially stretched polyamide film containing mass% and having excellent slipperiness under high humidity has been studied. Further, Patent Document 3 is characterized in that a polyamide resin is blended with an inorganic filler particle having a specific specific surface area surface-treated with an organopolysiloxane and other inorganic filler particles in combination. Resin compositions are being studied.

By the way, films used for food applications and the like have always been required to have higher quality with the times. Not only compounding but also laminating is an important technique for imparting the function of the film, and the current mainstream is to use a multilayer film in which a plurality of layers are laminated. On the other hand, from the viewpoint of waste reduction and cost reduction, the film is also required to be thin. Under these circumstances, the thickness of the surface layer of recently laminated films tends to be very thin.
If the film has a layer thickness of 15 μm or more, a filler having a relatively large particle size such as Patent Documents 2 and 3 can be used, but in a very thin surface layer of a film thinned in total, If an inorganic filler having a large particle size is used, the unevenness formed by the inorganic filler is too large, and there is a concern that the transparency may be deteriorated or printing omission may occur.
Under these circumstances, even a thin surface layer has good slipperiness under high humidity, has good film appearance and transparency, does not cause post-processing defects such as printing omissions and corona treatment defects, and is a food product. There is a need for a film that also meets hygienic standards.

JP-A-63-251460 JP-A-2002-348465 Japanese Unexamined Patent Publication No. 2006-241439

The present invention has been made in view of the above problems, and in a multilayer film having a thin surface layer made of a polyamide resin, it has good slipperiness under high humidity, and the film appearance and transparency are also good. The purpose is to provide a film that also satisfies food hygiene standards.

As a result of diligent studies, the present inventors have succeeded in obtaining a film capable of solving the above-mentioned problems of the prior art, and have completed the present invention.
That is, in the thermoplastic resin multilayer film, at least one surface layer contains the polyamide resin (A) as a main component and contains the inorganic fillers (B) and (C), and the particle size of the inorganic filler (B) is a laser. The 50% diameter (d50) in the volume cumulative distribution by the diffraction method is 1 μm or more and 6 μm or less, the 10% diameter (d10) is 0.1 μm or more and 0.5 μm or less, and the 90% diameter (d90) and 10% diameter (d90). The difference from d10) is 5 μm or more and 10 μm or less, and the particle size of the inorganic filler (C) is 1.5 μm or more and 3.5 μm or less in the 50% diameter (d50) in the volume cumulative distribution by the laser diffraction method. The% diameter (d10) is 0.3 μm or more and 1.0 μm or less, the difference between the 90% diameter (d90) and the 10% diameter (d10) is 0.5 μm or more and 5 μm or less, and the inorganic filler (B) and ( Each of C) has a specific surface area of 1 m ² / g or more and 200 m ² / g or less, and is surface-treated with an alkoxysilane compound, and the content ratio of the total mass of the inorganic fillers (B) and (C) is It is achieved by a multilayer film characterized by being 0.01% by volume or more and 0.50% by volume or less with respect to the total mass of the compositions constituting the surface layer.

According to the present invention, it has good slipperiness under high humidity, and the film appearance and transparency are also good. In addition, by combining a plurality of types of specific inorganic fillers, it is possible to obtain a film that does not cause problems in post-processing of the film such as printing omission and poor corona treatment even though it has a thin surface layer and contains only the inorganic filler. Can be done.

It is a figure explaining the cumulative distribution of particle size. It is an example figure of a multilayer film (10) composed of three layers of a surface layer (1, 3) and a middle layer (2). It is an example figure of the multilayer film (20) which consists of 5 layers of a surface layer (11, 15) and a middle layer (12, 13, 14).

Hereinafter, the multilayer stretched film of the present invention (hereinafter referred to as “the film”) and the package of the present invention will be described as an example of the embodiment of the present invention. However, the scope of the present invention is not limited to the embodiments described below.

In addition, in this specification, "as a main component" means that it is allowed to contain other components as long as it does not interfere with the action and effect of the resin contained as the main component. Further, although the term does not limit the specific content, it is 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, and 100% by mass or less of the total components. It is a component that occupies the range of.

<Polyamide resin (A)>
As the polyamide resin (A) used in this film, a resin obtained by polycondensation of lactam having a 3-membered ring or more, a polymerizable ω-amino acid, a dibasic acid and a diamine, etc. can be used.
Specific examples of the three-membered ring or more lactam include, for example, ε-caprolactam, γ-undecane lactam, and ω-lauryl lactam.
Specific examples of the polymerizable ω-amino acid include ω-aminocaproic acid, ω-aminoheptanoic acid, ω-aminononanoic acid, ω-aminoundodecanoic acid, and ω-aminododecanoic acid.

Specific examples of the above diamines include, for example, tetramethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4. -Adiamines such as totimethylhexamethylenediamine, 2,4,4-totimethylhexamethylenediamine, 1,3 / 1,4-bis (aminomethyl) cyclohexane, isophoronediamine, piperazine, bis (4-aminocyclohexyl) ) Alicyclic diamines such as methane and 2,2-bis- (4'-aminocyclohexyl) propane, and aromatic diamines such as metaxylylenediamine and paraximethylenediamine can be mentioned.
Specific examples of the above dicarboxylic acids include aliphatic dicarboxylic acids such as glutaric acid, adipic acid, pimelli acid, suberic acid, azelaic acid, sebatic acid, nonandionic acid, decandionic acid, undecandionic acid, and dodecandionic acid, and hexa. Alicyclic carboxylic acids such as hydroterephthalic acid and hexahydroisophthalic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid (1,2-body, 1,3-body, 1,4-body, 1,5-body, 1,6-body, 1,7-body, 1,8-body, 2,3-body, 2,6-body, 2,7-body), aromatic dicarboxylic acids such as sulfoisophthalic acid metal salts be able to.

Specific examples of the polyamide-based resin (A) derived from the above-mentioned three-membered ring or more lactam, polymerizable ω-amino acid, diamine and dicarboxylic acid include, for example, polyamide 4, polyamide 6, polyamide 7, and polyamide. 11, Polyamide 12, Polyamide 4, 6, Polyamide 6, 6, Polyamide 6, 9, Polyamide 6, 10, Polyamide 6, 11, Polyamide 6T, Polyamide 6I, Polyamide MXD6 (Polymethoxylylen adipamide), Polyamide 6- 6,6, Polyamide 6-6,10, Polyamide 6-6,11, Polyamide 6,12, Polyamide 6-6, 12, Polyamide 6-6T, Polyamide 6-6I, Polyamide 6-6, 6-6,10 , Polyamide 6-6, 6-12, Polyamide 6-6, 6-6, 12, Polyamide 6, 6-6T, Polyamide 6, 6-6I, Polyamide 6T-6I, Polyamide 6, 6-6T-6I, etc. Can be mentioned. These polyamide-based resins may be homopolymers, copolymers, or mixtures thereof. Among these, polyamide 6, polyamide 6/66, polyamide 6/12, and polyamide 6/66/12 are preferably used as main components, and polyamide 6 is preferably used.

The polyamide resin (A) is JIS K6920-2 in terms of miscibility between the polyamide resin (A) and the inorganic fillers (B) and (C), and in terms of forming a thin surface layer and transparency. : The relative viscosity measured according to 2009 (solvent: 96% sulfuric acid) is preferably 1.0 or more and 5.0 or less, and more preferably 2.0 or more and 4.0 or less.
Further, when the relative viscosity of the polyamide resin (A) is 1.0 or more, the mechanical properties of the obtained film are good, and when it is 5.0 or less, the viscosity at the time of melt extrusion of the resin does not increase. , It is easy to form a surface layer or to form a film when coextruding with other layers.

<Inorganic filler>
As the inorganic fillers (B) and (C) contained in the surface layer of this film, those having a predetermined particle size in the volume cumulative distribution of the particle size distribution are used.
The volume cumulative distribution of the inorganic filler is measured by laser diffraction. For example, the measurement is carried out using a laser diffraction type particle size distribution meter Mastersizers manufactured by Malvern and water as a solvent.

Here, the volume cumulative distribution of particle size will be described.
In general, the size of powder, which is a particle as an aggregate, is represented by a large number of measured values as a distribution of abundance ratio for each particle size, that is, a particle size distribution. The reference of the abundance ratio may be a case where a volume standard (volume distribution) is used, a case where a number standard (number distribution) is used, or the like, and the volume distribution is measured by a laser diffraction / scattering method. Further, the particle size distribution may represent the frequency at each particle size or the frequency accumulated with respect to the particle size. FIG. 1 shows an example of a cumulative distribution map of particle size.
The 50% diameter (d50) in the volume cumulative distribution is the side with a large particle size when the powder is divided into a large particle size side and a small particle size side in the cumulative volume distribution of the particle size. It is the diameter at which the distribution and the distribution on the smaller side are 50% each of the equal amount. Similarly, the 10% diameter (d10) is the diameter at which the smaller side is 10%, and the 90% diameter (d90) is the diameter at which the smaller side is 90%. Therefore, the difference between the 90% diameter (d90) and the 10% diameter (d10) means that the particle size distribution is wide, and the larger the difference, the more primary particles having different particle sizes are present.

In this film, in order to combine good slipperiness under high humidity with the appearance and transparency of the film, it is not just an average particle size as an index of the particle size forming fine protrusions on the surface layer. It became clear that the distribution of the particle size is essential, and it was specified using the 50% diameter, 10% diameter, and 90% diameter in the volume cumulative distribution of the particle size.
Further, it was found that the combined use of the inorganic fillers (B) and (C) having different particle size distribution indexes greatly improved the transparency and the slipperiness under high humidity, and in the volume cumulative distribution of each particle size. The 50% diameter, 10% diameter, and 90% diameter were specified. The inorganic filler (C) thus identified has an effect mainly of imparting slipperiness to the film, and the inorganic filler (B) has a particle size that includes a wide range of particles from relatively fine particles to large particles. , It has the effect of complementing the slipperiness of the inorganic filler (C) and imparting high transparency to the film.

<Inorganic filler (B)>
The inorganic filler (B) contained in the surface layer of this film has a 50% diameter (d50) of 1 μm or more and 6 μm or less in a volume cumulative distribution by a laser diffraction method, and a 10% diameter (d10) of 0.1 μm or more. It is 5 μm or less, and the difference between the 90% diameter (d90) and the 10% diameter (d10) is 5 μm or more and 10 μm or less.
The upper limit of the 50% diameter (d50) is preferably 4 μm or less, and the lower limit is preferably 2 μm or more. The upper limit of the 10% diameter (d10) is preferably 0.4 μm or less, and the lower limit is preferably 0.2 μm or more. The upper limit of the difference between the 90% diameter (d90) and the 10% diameter (d10) is preferably 8 μm or less, and the lower limit is preferably 6 μm or more.

When the 50% diameter (d50) is within the above range, it is an appropriate size that is too large to cause deterioration of film transparency or print omission. When the 10% diameter (d10) is within the above range, fine protrusions that do not affect the transparency can be formed on the film surface, and the difference between the 90% diameter (d90) and the 10% diameter (d10) is different. Within the above range, for example, when the polyamide resin (A) and the inorganic filler are compounded by a twin-screw extruder, the secondary aggregation of the inorganic filler collapses to form suitable protrusions for imparting slipperiness of the film. easy.
Further, when the inorganic filler (B) is used in combination with the inorganic filler (C) having a different particle size distribution index, the transparency and the slipperiness under high temperature and high humidity are greatly improved.

The shape of the inorganic filler (B) is not particularly limited as long as surface protrusions are formed on the surface and a film having excellent slipperiness can be obtained, and the shape is powdery, particulate, flake, plate, fibrous, needle-like. , Cross-shaped, mat-shaped, or any other shape, but particle-shaped one is preferable. Even if it is in the form of particles and has a spherical or cubic shape, even if strong shear occurs during kneading into the resin, it will be dispersed in the resin without losing its shape and the slipperiness of the film surface will be improved. It is preferable because it is easy to make it.

The specific surface area of the inorganic filler (B) is ^{1 m} 2 / g or more 200 meters ² / g or less, the upper limit is preferably 150 meters ² / g or less, more preferably 100 m ² / g. The lower limit is ^{preferably 5 m 2} / g or more, and more preferably 10 m ² / g or more. The specific surface area of the inorganic filler can be measured by the BET method.

If the inorganic filler (B) has a specific surface area, the compatibility with the polyamide resin is improved when the surface is treated with a surface treatment agent such as a silane coupling agent, and a film having excellent transparency is produced. can do. Specifically, when the specific surface area is 200 m ² / g or less, the surface treatment agent can sufficiently cover the filler surface, the compatibility with the polyamide resin (A) becomes good, and the matrix is formed. Inorganic fillers are easily dispersed in the polyamide resin (A), the occurrence of coarse particle aggregation can be suppressed, and even when this film is obtained by biaxial stretching, void formation and transparency are achieved. Deterioration and omission during printing can be suppressed. Further, when the specific surface area is 1 m ² / g or more, the primary particles do not become coarse monodisperse particles, which is preferable.

Specific examples of the inorganic filler (B) include gel type silica, precipitated type silica, silica such as spherical silica, talc, kaolin, montmorillonite, zeolite, mica, glass flakes, wollastonite, potassium titanate, magnesium sulfate, and sepiolite. , Zonolite, aluminum borate, glass beads, calcium silicate, calcium carbonate, titanium oxide, barium sulfate, zinc oxide, magnesium hydroxide and the like. These can be used alone or in combination of two or more. Among these, silica, talc, kaolin, and zeolite are preferable from the viewpoint of dispersibility.

<Inorganic filler (C)>
The inorganic filler (C) used in the present invention has a 50% diameter (d50) of 1.5 μm or more and 3.5 μm or less and a 10% diameter (d10) of 0.3 μm or more in the volume cumulative distribution by laser diffraction method. It is 1.0 μm or less, and the difference between the 90% diameter (d90) and the 10% diameter (d10) is 0.5 μm or more and 5 μm or less.
The upper limit of the 50% diameter (d50) is preferably 3.0 μm or less, more preferably 2.5 μm or less, and the lower limit is more preferably 2.0 μm or more. The lower limit of the 10% diameter (d10) is preferably 0.4 μm or more, more preferably 0.5 μm or more. The difference between the 90% diameter (d90) and the 10% diameter (d10) is preferably an upper limit of 3 μm or less, more preferably 2 μm or less, and a lower limit of 1.0 μm or more.

When the 50% diameter (d50) and 10% diameter (d10) of the volume cumulative distribution are within the above ranges, fine protrusions that do not affect the transparency can be formed on the film surface, and the 90% diameter (d90). When the difference between 10% and 10% diameter (d10) is within the above range, even if secondary agglomerates of particles are present, the agglomeration is broken by the film extruder and protrusions suitable for imparting slipperiness can be formed. ..
Further, when the inorganic filler (C) is used in combination with the inorganic filler (B) having a different particle size distribution index, the transparency and the slipperiness under high temperature and high humidity are greatly improved.

The shape of the inorganic filler (C) is not particularly limited as long as surface protrusions are formed on the surface and a film having excellent slipperiness can be obtained, and the shape is powdery, particulate, flake, plate, fibrous, needle-like. , Cross-shaped, mat-shaped, or any other shape, but particle-shaped one is preferable. Even if it is in the form of particles and has a spherical or cubic shape, even if strong shear occurs during kneading into the resin, it will be dispersed in the resin without losing its shape and the slipperiness of the film surface will be improved. It is preferable because it is easy to make it.

The specific surface area of the inorganic filler (C) is 1 m ² / g or more and 200 m ² / g or less, the upper limit is ^{preferably 150 m 2} / g or less, and the lower limit is preferably 3 m ² / g or more, 5 m ² / g or more. Is more preferable. The specific surface area of the inorganic filler can be measured by the BET method.

If the inorganic filler (C) has a specific surface area, the compatibility with the polyamide resin is improved when the surface is treated with a surface treatment agent such as a silane coupling agent, and a film having excellent transparency is produced. can do. Specifically, when the specific surface area is 200 m ² / g or less, the surface treatment agent can sufficiently cover the filler surface, and the compatibility with the polyamide resin (A) becomes good. Therefore, even when the film is obtained by biaxial stretching, the formation of voids and the deterioration of transparency can be suppressed. At the same time, aggregation of the fillers can be suppressed, large protrusions that cause print omission are not formed on the film surface, and printability is also good. Further, when the specific surface area is 1 m ² / g or more, the primary particles do not become coarse monodisperse particles, which is preferable.

Specific examples of the inorganic filler (C) include gel type silica, precipitated type silica, silica such as spherical silica, talc, kaolin, montmorillonite, zeolite, mica, glass flakes, wollastonite, potassium titanate, magnesium sulfate, and sepiolite. , Zonolite, aluminum borate, glass beads, calcium silicate, calcium carbonate, titanium oxide, barium sulfate, zinc oxide, magnesium hydroxide and the like. These can be used alone or in combination of two or more. Among these, silica, talc, kaolin, and zeolite are preferable from the viewpoint of dispersibility.

<Surface treatment of inorganic fillers (B) and (C)>
It is desirable that the inorganic fillers (B) and (C) used in this film are surface-treated. By covering the surface of the inorganic filler with a suitable surface treatment agent, the compatibility with the polyamide resin (A) which is a matrix is improved, and the dispersibility of the inorganic filler is improved. Therefore, for example, even when the film is stretched, it is possible to suppress whitening due to voids and the occurrence of coarse protrusions that may cause print omission due to aggregation of fillers, such as print omission during gravure printing. No problems occur.

As the surface treatment agent used for the inorganic fillers (B) and (C), a silane coupling agent is preferably used. Examples of the silane coupling agent generally include an alkoxysilane compound containing an amino group, an epoxy group, a mercapto group, an isocyanato group, a hydroxyl group, or the like. These are preferably used because they have excellent affinity between the polyamide resin (A) and the above-mentioned inorganic fillers (B) and (C).

Specifically, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltriethoxysilane, γ-aminodithiopropyltrihydroxysilane, γ- (polyethyleneamino) propyltrimethoxysilane, N-β- (aminopropyl) -γ-aminopropyl Amino group-containing alkoxysilane compounds such as methyldimethoxysilane, N- (trimethoxysilylpropyl) -ethylenediamine, and γ-dibutylaminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, γ-ureidopropyltrimethoxysilane, γ- (2-Ureidoethyl) Ureido group-containing alkoxysilane compounds such as aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysisilane, β- (3,4-epoxycyclohexyl) ) Epoxy group-containing alkoxysilane compounds such as ethyltrimethoxysilane, mercapto group-containing alkoxysilane compounds such as γ-mercaptopropyltrimethoxysilane and γ-mercaptopropyltriethoxysilane, γ-isocyanatopropyltriethoxysilane, γ-isosia Natopropyltrimethoxysilane, γ-isocyanatopropylmethyldimethoxysilane, γ-isocyanatopropylmethyldiethoxysilane, γ-isocyanatopropylethyldimethoxysilane, γ-isocyanatopropylethyldiethoxysilane, γ-isocyanatopropyltri Examples thereof include isocyanato group-containing alkoxysilane compounds such as chlorosilane, and hydroxyl group-containing alkoxysilane compounds such as γ-hydroxypropyltrimethoxysilane and γ-hydroxypropyltriethoxysilane. These can be used alone or in combination of two or more.
Among these, amino group-containing alkoxysilane compounds such as γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, γ- (2-aminoethyl) aminopropyltrimethoxysilane, and γ-aminopropyltriethoxysilane, and γ -Glysidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β- (3,4-epoxycyclohexyl) Epoxy group-containing alkoxysilane compounds such as ethyltrimethoxysilane and β- (3,4-epoxycyclohexyl) ethyltriethoxysilane are preferable, and 3-aminopropyl-triethoxysilane is preferably used.

The method for surface-treating the inorganic fillers (B) and (C) with the surface-treating agent is not particularly limited, but for example, the surface-treating agent or the surface-treating agent solution is added dropwise or by spray to the inorganic filler particles, and Henshell A dry treatment method in which the mixture is stirred so as to be uniform with an appropriate device such as a mixer and then dried at a predetermined temperature, or the inorganic filler particles are dispersed in water or the like to form a slurry, and the surface treatment agent is applied while stirring the slurry. In addition, a wet treatment method in which dehydration and drying are performed thereafter can be mentioned.

The concentration of the surface treatment agent added when performing the surface treatment is preferably 0.1 to 20% by mass, preferably 0.2 to 15% by mass, based on each of the inorganic fillers (B) and (C). More preferably, it is more preferably 0.5 to 10% by mass. If the addition of the surface treatment agent is less than 0.1% by mass, the affinity between the inorganic filler and the polyamide resin (A) becomes insufficient, and the dispersibility deteriorates. On the other hand, even if it is added in a large amount exceeding 20% by mass, not only the effect of improving the dispersibility is hardly enhanced, but also problems such as impairing the mechanical properties of the film and bleeding out of the surface treatment agent to the film occur. ..

<Combining of inorganic fillers (B) and (C)>
In the present invention, by using the above two types of inorganic fillers (B) and inorganic fillers (C) having different particle size distribution indexes in combination, the transparency is excellent and the slipperiness is significantly improved even under high humidity. An improved film can be obtained, and the effect can be obtained even if the film surface layer is thinned in order to cope with the recent thinning of the package. In addition, the occurrence of fish eyes can be suppressed, and defects in post-processing such as printing omission and corona treatment do not occur. That is, the blending of the inorganic fillers (B) and (C) has such various good properties and can satisfy the required quality of the packaging film.

The content of the inorganic filler (B) and the inorganic filler (C) in the surface layer of this film is such that the finally obtained film has excellent slipperiness and is optically such as transparency and surface glossiness. It should be within a range in which the characteristics can be maintained, and varies depending on the type, shape, and size of the inorganic filler particles, the film forming method, the draw ratio, and the like.
The content ratio is 0.01% by mass or more and 0.50% by mass or less as the ratio of the mass of the surface layer, that is, the total mass of the inorganic fillers (B) and (C) to the total mass of the compositions constituting the surface layer. It is preferably 0.05% by mass or more and 0.40% by mass or less, and more preferably 0.10% by mass or more and 0.30% by mass or less. When the content ratio is 0.01% by mass or more, the slipperiness improving effect of the obtained film is sufficient, while when the content ratio is 0.50% by mass or less, the transparency, appearance, etc. of the film are impaired. It is preferable that the film surface is not uneven, and printing omissions and corona processing defects due to too many irregularities on the film surface are unlikely to occur.

The inorganic fillers (B) and (C) are used by measuring the mass of the surface-treated inorganic filler and blending it with the composition of the surface layer. Further, in the formed film, the surface layer is separated and incinerated, so that the total mass of the inorganic fillers can be measured and the content ratio in the surface layer can be calculated.

The mass ratio of the inorganic fillers (B) and (C) is preferably 1: 5 to 5: 1, more preferably 1: 4 to 2: 1, and even more preferably 1: 3 to 1: 1. By containing the inorganic fillers (B) and (C) having different particle size distribution indexes in combination at such a ratio, good transparency and slipperiness under high humidity can be obtained at the same time.

Mixing the polyamide resin (A) with the inorganic filler (B) and the inorganic filler (C) is carried out by the polyamide resin (A) in a pellet state, more preferably in a powder state, or a raw material thereof, and the inorganic filler particles. A method of blending a predetermined amount at room temperature using a high-speed rotary mixer such as a Henschel mixer used for ordinary mixing, a low-speed rotary mixer such as a cone blender or a tumbler, or a method of further blending the blend at a Banbury mixer or a supermarket. Using equipment such as a mixer, mixing roll, twin-screw continuous mixer, brabender plastograph, kneader, single-screw extruder, twin-screw extruder, etc. It is carried out by a method known per se, such as a kneading method, but among them, a method of master-batch kneading in a twin-screw extruder is preferable. Further, the two types of inorganic fillers (B) and the inorganic filler (C) may be added at the same time or separately.

<Organic lubricant>
The surface layer of this film may further contain a fatty acid amide as an organic lubricant. Specific examples of the fatty acid amide include behenic acid amide, stearic acid amide, montanic acid amide, erucic acid amide, hydroxystearic acid amide, oleic acid amide, ricinoleic acid amide, N-stearyl stealic acid amide, and methylol stearic acid amide. Monoamide compounds such as, ethylenebislauric acid amide, ethylenebisstearic acid amide, ethylenebishydroxystearic acid amide, hexamethylenebisbechenic acid amide, hexamethylenebisoleic acid amide, N, N-distearylisophthalic acid amide, etc. Bisamide compounds and the like. Of these, ethylene bisstearic acid amide is preferably used.

The content ratio of the fatty acid amide is preferably 0.01% by mass or more and 0.3% by mass or less, and 0.05% by mass or more, based on the mass of the surface layer, that is, the total mass of the compositions constituting the surface layer. It is more preferably 0.2% by mass or less. Within this range, the slipperiness of the film is good at both normal temperature and high humidity.

<Other ingredients>
Other resins may be appropriately added to the surface layer of the film as long as the effects of the present invention are not impaired.
Each layer of this film is a heat stabilizer, an antioxidant, an ultraviolet absorber, a weather resistant agent, a lubricant, a filler, a nucleating agent, a plasticizer, a foaming agent, an antiblocking agent, as long as the physical properties are not impaired. It can appropriately contain a cloud-proofing agent, a flame retardant, a dye, a pigment, a stabilizer, a coupling agent, an impact-resistant improving material and the like.

<Composition of this film>
The structure of this film is such that the multilayer film may have at least one surface layer containing the above-mentioned polyamide resin (A), inorganic filler (B), and inorganic filler (C), and the number of layers is not limited. , It is possible to form a layer structure in which other layers are appropriately combined as needed. The other layers may be at least one layer, and a plurality of two or more layers may be laminated if necessary. For example, an example of a three-layer film configuration is shown in FIG. 2, and an example of a five-layer film configuration is shown in FIG.
Further, having the surface layers having the above composition on both sides of the film is more preferable in terms of the slipperiness of winding and unwinding the roll of the film, and is useful in the secondary processing using the film.

Specific examples of the resins constituting the other layers include polyethylene, ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer, and ethylene- (meth) acrylic acid. Ethylene resins such as ester copolymers, polypropylene, propylene resins such as propylene-α-olefin copolymers, polyester resins, polyamide resins, vinyl chloride resins, styrene resins, (meth) acrylic resins, Examples thereof include polyvinyl alcohol and ethylene-vinyl alcohol copolymers. Further, in order to improve the interlayer adhesiveness of each layer, an adhesive layer may be arranged as needed.

As a preferable configuration example in this film, the middle layer contains, for example, a polyamide resin (polyamide MXD6 resin) having a gas barrier property containing polymethoxylylen adipamide as a main component, an ethylene-vinyl alcohol copolymer or the like as a main component. It can be mentioned that a resin layer having a gas barrier property is arranged and a polyamide-based resin layer of the present invention is arranged as a surface layer.
If necessary, an adhesive layer, a sealant, a metal leaf, paper, or the like can be further laminated on the film by a dry laminating method, a wet laminating method, a sand laminating method, an extrusion laminating method, or the like.
In addition, this film can be subjected to surface treatment such as corona treatment, printing, coating, and thin film deposition, and surface treatment, if necessary.

<Manufacturing method of this film>
The method for producing this film is not particularly limited as long as it can be a multilayer film, but a coextrusion method is preferable, and a coextrusion multilayer stretching method is more preferable. For example, an unstretched multilayer film coextruded with a feed block or a multi-manifold die may be produced, and a biaxially stretched film may be produced by a tenter type simultaneous biaxial stretching method. Further, a stretched film may be obtained by a sequential biaxial stretching method in which the film is stretched in the vertical direction by a roll-type longitudinal stretching machine and then laterally stretched by a tenter-type stretching machine. Further, it is also possible to carry out a tubular stretching method in which a tubular sheet formed from an annular die is stretched simultaneously in the vertical and horizontal directions in an inflationary manner by means of gas pressure. The stretching step may be carried out continuously following the production of the unstretched film, or the unstretched film may be wound once and carried out as a separate step.

The draw ratio is preferably 1.5 to 5 times in both the vertical direction and the horizontal direction, and more preferably 2 to 4 times. The stretching temperature is preferably 30 to 220 ° C, more preferably 40 to 200 ° C.
After the stretching step, the end portion is continuously held by a tenter clip, and the temperature is 200 ° C. or higher and the melting start temperature of the polyamide resin (A) + 10 ° C. or lower in a tenter oven for about 1 second to 2 minutes, preferably about 1 second to 2 minutes. It is preferable to perform the heat treatment for a time of 1 second to 30 seconds, more preferably 3 seconds to 15 seconds.

<Thickness of this film>
The thickness of the surface layer of this film is not particularly limited, but is generally about 1 μm or more and 15 μm or less. The present invention is characterized in that even a thin surface layer has a remarkable effect of being excellent in transparency and slipperiness under high humidity, for example, 10 μm or less, further 5 μm or less. Even in this case, a sufficient effect can be exhibited.
The total thickness of the film is not particularly limited, but for example, when workability and practicality are taken into consideration, the lower limit is preferably 8 μm or more, more preferably 10 μm or more, and further preferably 15 μm or more. The upper limit value is preferably 50 μm or less, more preferably 30 μm or less. When the total thickness of the film is within the above range, the rigidity of the film is sufficient, and the mechanical properties such as pinhole resistance and impact resistance are also excellent.

<Physical characteristics of this film>
(1) Transparency In this film, the total haze value measured based on JIS K7136 is preferably 10% or less, more preferably 5.0% or less, still more preferably less than 4.5%. As long as the value of all haze is within the relevant range, this film is particularly excellent in transparency, has good appearance, and has good visibility of the contents of the package.

(2) Slipperiness In this film, the values of the static friction coefficient and the dynamic friction coefficient measured under the condition of 23 ° C. and 50% relative humidity based on JIS K7125 are preferably less than 0.50, preferably 0.40 or less. Is more preferable, and 0.35 or less is further preferable.
In addition, although the main component of the surface layer is a polyamide resin, this film exhibits an excellent effect of having good slipperiness under high humidity. Both the static friction coefficient and the dynamic friction coefficient measured under the condition of 23 ° C. and 80% relative humidity based on JIS K7125 are preferably less than 0.50, more preferably 0.40 or less, still more preferably 0.35 or less. ..
As long as the values of the static friction coefficient and the dynamic friction coefficient are within the relevant range, the film is particularly excellent in slipperiness, and blocking is unlikely to occur in processes such as winding, slitting, and rewinding during film production. In addition, polyamide-based resin films have good tensile elongation, tensile strength, and pinhole resistance, so while they are often used in liquid-filled packaging applications, this film has good film slipperiness under high humidity. Due to its good characteristics, blocking troubles do not occur and high-speed filling is possible, which is effective in improving packaging production efficiency.

(3) Secondary workability Since the surface unevenness formed by the inorganic filler is appropriate for this film, for example, defects in corona treatment and missing dots in gravure printing are unlikely to occur, and the secondary processing of the film is good. Can be done.

<Use of this film>
Since this film is excellent in transparency, slipperiness, mechanical properties, etc., it is not particularly limited as long as it is used for such quality, but for example, for food packaging and various lids. It can be suitably used for materials, miscellaneous goods packaging, toiletry product packaging, cosmetic packaging, pharmaceutical packaging, industrial product packaging, and the like. Due to the characteristics of this film, it can be suitably used for boiled / retort food packaging, various vacuum packaging, and the like.

<Packaging using this film>
This film can be made into a package by subjecting it to bag making or the like. The shape of the package is not particularly limited, but for example, packaging bags such as two-way seal bags, three-way seal bags, gassho bags, gusset bags, stand bags, side seal bags, bottom seal bags, containers, containers, etc. For example, the lid material of.

Examples are shown below, but these do not limit the present invention in any way. Various measured values and evaluations of the raw materials and test pieces displayed in the present specification were carried out as follows.

<Evaluation method>
(1) For the films obtained in the All Haze Examples, the value (%) of the film having a thickness of 18 μm was measured based on JIS K7136: 2000.

(2) Sliding property The static friction coefficient and the dynamic friction coefficient of the film obtained in the examples were measured under the conditions of 23 ° C. relative humidity 50% and 23 ° C. relative humidity 80% based on JIS K7125: 1999. ..

(3) Printability The film obtained in the example was subjected to gravure printing using a gravure printing plate having a cell pitch of 100 μm and a gradation of 30%. For the ink, "Rio Alpha S R39 Indigo" manufactured by Toyo Ink Co., Ltd. and the dedicated No. Two solvents were used, and the viscosity was adjusted to 17 seconds with Zahn cup # 3. Next, 10 points having a size of 15 mm × 30 mm were cut out from the printed film, and the places where the print without ink was missing were counted. When the average number of missing prints of 10 points was 20 or less, it was evaluated as "◯", and when it was 21 or more, it was evaluated as "x".

^{(4) Gas barrier property The oxygen permeability (cc / m 2} / 24h / atm) of the film obtained in the example was measured under the condition of an atmosphere of 23 ° C. and 50% relative humidity based on the JIS K7126-2 method. did.

<Material used>
<Polyamide resin (A)>
(A) -1: Polyamide 6 resin, relative viscosity 3.34 (solvent 96% sulfuric acid)

The following inorganic fillers (B) and (C) "d50", "d10", and "d90" have 50% diameter, 10% diameter, and 90% diameter in the cumulative volume distribution, respectively, and "d90-d10" is , Represents the difference between 90% diameter and 10% diameter.
<Inorganic filler (B)>
(B) -1: Atypical silica, d50 = 3.5 μm, d10 = 0.4 μm, d90 = 6.6 μm, d90-d10 = 6.2 μm, average particle size = 2.0 μm, specific surface area = 55 m ² / g
(B) -2: Atypical silica, d50 = 5.1 μm, d10 = 0.45 μm, d90 = 9.8 μm, d90-d10 = 9.35 μm, average particle size = 3 μm, specific surface area = 40 m ² / g
(B) -3: Talc, d50 = 3 μm, d10 = 0.3 μm, d90 = 8.0 μm, d90-d10 = 7.7 μm, specific surface area = 30 m ² / g
(B) -4: Kaolin, d50 = 2.2 μm, d10 = 0.4 μm, d90 = 7.8 μm, d90-d10 = 7.4 μm, average particle size = 1.3 μm, specific surface area = 13 m ² / g
(B) -5: Atypical silica, d50 = 5.5 μm, d10 = 0.4 μm, d90 = 6.2 μm, d90-d10 = 5.8 μm, average particle size = 4.0 μm, specific surface area = 330 m ² / g

<Inorganic filler (C)>
(C) -1: Spherical zeolite, d50 = 2.2 μm, d10 = 0.7 μm, d90 = 3.6 μm, d90-d10 = 2.9 μm, average particle size = 2.0 μm, specific surface area = 9 m ² / g
(C) -2: Spherical silica, d50 = 2.3 μm, d10 = 0.9 μm, d90 = 3.7 μm, d90-d10 = 2.8 μm, average particle size = 1.6 μm, specific surface area = 149 m ² / g
(C) -3: Atypical silica, d50 = 7.6 μm, d10 = 0.8 μm, d90 = 10.2 μm, d90-d10 = 9.4 μm, average particle size = 6.0 μm, specific surface area = 360 m ² / g

<Surface treatment agent for inorganic filler>
(S) -1: 3-Aminopropyltriethoxysilane (s) -2: γ-glycidoxypropyltrimethoxysilane (s) -3: Sodium stearate

(Example 1)
As the inorganic filler (B), (b) -1 surface-treated with (s) -1 at a concentration of 5% by mass was used. As the inorganic filler (C), (c) -1 surface-treated with (s) -1 at a concentration of 0.5% by mass was used.
In producing a five-layer multilayer film, a resin obtained by mixing a polyamide resin (A), an inorganic filler (B), and (C) in the first layer and the fifth layer, which are surface layers, at the content ratios shown in Table 1. The composition was used. (A) -1 was used for the second layer, the third layer, and the fourth layer.
The film uses a 5-layer feed block and a multi-manifold die, and uses a single-screw extruder with a diameter of 40 mm for the first and fifth layers, and a single-screw extruder with a diameter of 32 mm for the second, third, and fourth layers. The first to fifth layers were coextruded at 250 ° C. to obtain an unstretched multilayer film. The obtained unstretched multilayer film was stretched three times in the longitudinal direction by a roll-type stretching machine under the condition of 55 ° C., and then the end portion of the vertically stretched film was held by a tenter clip and 120 ° C. in a tenter oven. After stretching 3.5 times in the lateral direction under the above conditions, the film was heat-fixed at 220 ° C. and laterally relaxed by 7%. Then, the film was cooled to room temperature, both ends corresponding to the grips of the clips were trimmed, and the trimmed multilayer stretched film was wound into a roll.
The thickness of each of the obtained five-layer stretched films was about 4.2 μm for the first and fifth layers (surface layer), about 2.4 μm for the second and fourth layers, and about about 2.4 μm for the third layer (middle layer). It was 4.8 μm and had a total thickness of about 18 μm.
Table 1 shows the results of evaluation of the obtained multilayer film.

(Example 2)
As the inorganic filler (B), (b) -1 surface-treated with (s) -2 at a concentration of 5% by mass was used. As the inorganic filler (C), (c) -1 was surface-treated with (s) -2 at a concentration of 0.5% by mass of (s) -2. Other than that, a multilayer film was obtained in the same manner as in Example 1 and evaluated.

(Example 3)
A film was obtained and evaluated in the same manner as in Example 1 except that an ethylene-vinyl alcohol resin was used for the third layer.

(Example 4)
A film was obtained and evaluated in the same manner as in Example 1 except that the polyamide MXD6 resin was used for the third layer.

(Example 5), (Example 6)
A multilayer film was obtained in the same manner as in Example 1 except that the contents of the inorganic fillers (B) and (C) were changed to the ratios shown in Table 1, and evaluation was performed.

(Example 7)
A multilayer film was obtained and evaluated in the same manner as in Example 1 except that (c-2) surface-treated with (s) -1 at a concentration of 5% by mass was used as the inorganic filler (C). ..

(Example 8)
A multilayer film was obtained and evaluated in the same manner as in Example 1 except that (b) -2, which was surface-treated with (s) -1 at a concentration of 5% by mass, was used as the inorganic filler (B). ..

(Example 9), (Example 10)
A multilayer film was obtained in the same manner as in Example 8 except that the contents of the inorganic fillers (B) and (C) were changed to the ratios shown in Table 1, and evaluation was performed.

(Example 11)
A multilayer film was obtained and evaluated in the same manner as in Example 8 except that (c) -2, which was surface-treated with (s) -1 at a concentration of 5% by mass, was used as the inorganic filler (C). ..

(Example 12)
A multilayer film was obtained in the same manner as in Example 11 except that the contents of the inorganic fillers (B) and (C) were changed to the ratios shown in Table 1, and evaluation was performed.

(Example 13)
A multilayer film was obtained and evaluated in the same manner as in Example 1 except that (b) -3, which was surface-treated with (s) -1 at a concentration of 5% by mass, was used as the inorganic filler (B). ..

(Example 14)
A multilayer film was obtained and evaluated in the same manner as in Example 1 except that (b) -4 surface-treated with (s) -1 at a concentration of 5% by mass was used as the inorganic filler (B). ..

(Comparative Example 1)
A multilayer film was obtained and evaluated in the same manner as in Example 1 except that the content of the inorganic filler (B) was changed to the ratio shown in Table 1 without using the inorganic filler (C).

(Comparative Example 2)
A multilayer film was prepared in the same manner as in Example 1 except that (b) -1 and (b) -2 surface-treated with (s) -1 at a concentration of 5% by mass were used as the inorganic filler (B). Obtained and evaluated.

(Comparative Example 3)
A multilayer film was obtained and evaluated in the same manner as in Example 7 except that the content of the inorganic filler (C) was changed as shown in Table 1 without using the inorganic filler (B).

(Comparative Example 4)
As the inorganic filler (C), (c) -1 surface-treated with (s) -1 at a concentration of 0.5% by mass and (c) -2 surface-treated with (s) -1 at a concentration of 5% by mass. A multilayer film was obtained in the same manner as in Example 7 except that the above was used, and evaluation was performed.

(Comparative Example 5)
A multilayer film was obtained in the same manner as in Example 1 except that the contents of the inorganic fillers (B) and (C) were changed to the ratios shown in Table 1, and evaluation was performed.

(Comparative Example 6)
A multilayer film was obtained in the same manner as in Example 11 except that the contents of the inorganic fillers (B) and (C) were changed to the ratios shown in Table 1, and evaluation was performed.

(Comparative Example 7)
A multilayer film was obtained and evaluated in the same manner as in Example 1 except that (b) -5, which was surface-treated with (s) -1 at a concentration of 5% by mass, was used as the inorganic filler (B). ..

(Comparative Example 8)
A multilayer film was obtained and evaluated in the same manner as in Example 1 except that (c) -3 surface-treated with (s) -1 at a concentration of 5% by mass was used as the inorganic filler (C). ..

(Comparative Example 9)
As the inorganic filler (B), (b) -1 surface-treated with (s) -3 at a concentration of 5% by mass was used. As the inorganic filler (C), (c) -1 surface-treated with (s) -3 at a concentration of 0.5% by mass was used. Other than that, a film was obtained in the same manner as in Example 1 and evaluated.

(Comparative Example 10)
A multilayer film was obtained and evaluated in the same manner as in Example 1 except that (b) -1 and (c) -1 which were not surface-treated were used as the inorganic fillers (B) and (C). Was done.

The films of Examples 1 to 14 had a haze of 5.0% or less, and the static friction coefficient and the dynamic friction coefficient were less than 0.50 under any condition, and the printability was also good. Further, in the films of Examples 1, 3, 5, and 7, the haze was less than 4.5%, and the static friction coefficient and the dynamic friction coefficient were 0.35 or less under any condition, which were highly evaluated.

Further, the oxygen permeability of the films of Examples, the third layer component is (a) -1 Example ^{25cc / m 2 / 24h / atm} , the third layer component ethylene - exemplary vinyl alcohol resin Example ^{3 was 0.8 cc / m 2} / 24h / atm, and in Example 4 in which the third layer component was a polyamide MXD resin, it was 7cc / m ^{2 / 24h / atm.}

In Comparative Examples 1 and 2, the inorganic filler (C) was not used and the friction coefficient was large.
In Comparative Examples 3 and 4, the inorganic filler (B) was not used and the haze was high.
In Comparative Examples 5 and 6, the total content of the inorganic fillers was high, the haze was high, and printing omissions occurred.
In Comparative Examples 7 and 8, the specific surface area of the inorganic filler was large, the haze was high, and printing omissions occurred.
In Comparative Example 9, the surface treatment agent for the inorganic filler was sodium stearate, the haze was high, the friction coefficient under high humidity was large, and printing omissions occurred.
In Comparative Example 10, an inorganic filler without surface treatment was used, the haze was high, and printing omissions occurred.

The multilayer film of the present invention has an excellent balance between transparency and slipperiness even with a thin surface layer, has good slipperiness even under high humidity, and has problems with post-processing such as printing omission and corona treatment failure. Since it does not occur, it can be suitably used for various packaging films that require thinning. Further, since it satisfies the food hygiene standard, it can be suitably used for food packaging.

1; Surface layer, 1st layer 2; Middle layer, 2nd layer 3; Surface layer, 3rd layer 10; Multilayer film 11; Surface layer, 1st layer 12; Middle layer, 2nd layer 13; Middle layer, 3rd layer 14 Middle layer, 4th layer 15; Surface layer, 5th layer 20; Multilayer film

Claims (6)

In the thermoplastic resin multilayer film
At least one surface layer contains a polyamide resin (A) as a main component and contains inorganic fillers (B) and (C).
The particle size of the inorganic filler (B) is 1 μm or more and 6 μm or less for the 50% diameter (d50) and 0.1 μm or more and 0.5 μm or less for the 10% diameter (d10) in the volume cumulative distribution by the laser diffraction method. The difference between the 90% diameter (d90) and the 10% diameter (d10) is 5 μm or more and 10 μm or less.
The particle size of the inorganic filler (C) is 1.5 μm or more and 3.5 μm or less for the 50% diameter (d50) in the volume cumulative distribution by the laser diffraction method, and 0.3 μm or more and 1.0 μm for the 10% diameter (d10). The difference between the 90% diameter (d90) and the 10% diameter (d10) is 0.5 μm or more and 5 μm or less.
The inorganic fillers (B) and (C) each have a specific surface area of 1 m ² / g or more and 200 m ² / g or less, and are surface-treated with an alkoxysilane compound.
A multilayer characterized in that the content ratio of the total mass of the inorganic fillers (B) and (C) is 0.01% by mass or more and 0.50% by mass or less with respect to the total mass of the composition constituting the surface layer. the film. The relative viscosity of the polyamide resin (A) measured according to JIS K6920-2: 2009 (solvent: 96% sulfuric acid) is 1.0 or more and less than 5.0, and the thickness of the surface layer is 5 μm or less. The multilayer film according to claim 1. The multilayer film according to claim 1 or 2, wherein both the static friction coefficient and the dynamic friction coefficient are less than 0.50 in an environment of 23 ° C. and 80% relative humidity. The multilayer film according to any one of claims 1 to 3, wherein the haze is 5.0% or less. The coextruded multilayer stretched film according to any one of claims 1 to 4, wherein the thermoplastic resin multilayer film has a middle layer containing a polyamide MXD6 (polymethaxylylene adipamide) resin or an ethylene-vinyl alcohol resin as a main component. A package using the multilayer film according to any one of claims 1 to 5.

Images