JP2018039260A - Multilayer film and package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multilayer film having a thin surface layer formed of a polyamide-based resin which has good slipperiness under high humidity, has good film appearance and transparency, and satisfies a food sanitation reference.SOLUTION: A multilayer film is a thermoplastic resin multilayer film of which at least surface layer contains a polyamide-based resin (A) as a main component, and inorganic fillers (B) and (C), where each of the inorganic fillers (B) and (C) has a particular particle size in volume accumulation distribution by a laser diffraction method and a specific area of 1-200 m/g and is surface-treated with an alkoxysilane compound, and a content ratio of the total mass of the inorganic fillers (B) and (C) is 0.01-0.50 mass% with respect to the total mass surface layer mass of a composition constituting the surface layer.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a multilayer film. 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-based 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 in The packaging film is required to have excellent slipperiness in order to increase workability and processing speed during processing such as printing, vapor deposition, lamination, and bag making. However, since a film using a polyamide-based resin has an amide group in the structure, slipping tends to deteriorate particularly in a high humidity environment, and blocking may occur between the films. It was. As a method for improving such blocking, for example, a method is known in which fine irregularities are formed on the film surface by blending an inorganic filler with a polyamide-based resin to reduce the contact area.

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

  Various techniques for achieving both transparency and slipping have been studied. For example, Patent Document 1 discloses a technique for improving slipperiness by suppressing a decrease in transparency by subjecting an inorganic filler to a surface treatment. It is being considered. In the method of Patent Document 1, although the balance between transparency and slipperiness is slightly improved, it has not achieved a practically satisfactory level, and at that time, slipperiness under high humidity was considered as an issue. There wasn't.

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

By the way, a film used for food applications and the like has always been required to have higher quality with the times. In addition to blending, lamination is also an important technique for imparting film functions, and the current mainstream is the use of multilayer films in which a plurality of layers are laminated. On the other hand, from the viewpoint of reducing the amount of waste and reducing costs, the film is also required to be thin. From such a situation, the thickness of the surface layer of a recently laminated film tends to be very thin.
If it is a film having a layer thickness of 15 μm or more, a filler having a relatively large particle size as in Patent Documents 2 and 3 can be used, but in a very thin surface layer of a total thinned film, 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 transparency may be deteriorated or printing may be lost.
From this situation, even with a thin surface layer, it has good slipperiness under high humidity, good film appearance and transparency, and does not cause problems in post-processing such as missing printing or poor corona treatment. There is a need for films that can meet sanitary standards.

JP-A-63-251460 JP 2002-348465 A JP 2006-241439 A

  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-based resin, has good slipperiness under high humidity, and has good film appearance and transparency. An object is to provide a film that also satisfies food hygiene standards.

As a result of intensive studies, the present inventors have succeeded in obtaining a film that can solve the above-described problems of the prior art, and have completed the present invention.
That is, in the thermoplastic resin multilayer film, at least one surface layer is composed mainly of the polyamide-based resin (A), contains the inorganic fillers (B) and (C), and the particle size of the inorganic filler (B) The 50% diameter (d50) in the cumulative volume 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 ( The difference from d10) is 5 μm or more and 10 μm or less, and the particle diameter of the inorganic filler (C) is 50% diameter (d50) in the volume cumulative distribution by laser diffraction method is 1.5 μm or more and 3.5 μm or less. % Diameter (d10) is 0.3 μm or more and 1.0 μm or less, and the difference between 90% diameter (d90) and 10% diameter (d10) is 0.5 μm or more and 5 μm or less, and inorganic filler (B) and C) are each not more than a specific surface area of ^{1 m} 2 / g or more 200 meters ² / g, it has been surface-treated with and alkoxysilane compounds, inorganic filler (B) and the content ratio of the total weight of (C) The multilayer film is characterized by being 0.01% by mass or more and 0.50% by mass or less based on the total mass of the composition constituting the surface layer.

  According to this invention, it has favorable slipperiness under high humidity, and the film appearance and transparency are also good. Moreover, by combining a plurality of types of specific inorganic fillers, a film that has a thin surface layer and contains only inorganic fillers, but does not cause defects in post-processing of the film such as missing printing or poor corona treatment, is obtained. Can do.

It is a figure explaining the cumulative distribution of a particle diameter. It is an example figure of the multilayer film (10) which consists 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 five 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 present film”) and the package of the present invention will be described as examples of the embodiment of the present invention. However, the scope of the present invention is not limited to the embodiments described below.

  In the present specification, “main component” is intended to allow other components to be included within a range that does not hinder the action and effect of the resin contained as the main component. Further, the term does not limit the specific content, but 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, based on the entire constituent components. It is a component that occupies the range.

<Polyamide resin (A)>
As the polyamide-based resin (A) used in the present film, there can be used those obtained by polycondensation of lactam having three or more members, polymerizable ω-amino acid, dibasic acid and diamine.
Specific examples of the lactam having three or more rings include ε-caprolactam, γ-undecanactam, and ω-lauryl lactam.
Specific examples of the polymerizable ω-amino acid include ω-aminocaproic acid, ω-aminoheptanoic acid, ω-aminononanoic acid, ω-aminoundecanoic acid, and ω-aminododecanoic acid.

Specific examples of the diamine include tetramethylene diamine, hexamethylene diamine, heptamethylene diamine, octamethylene diamine, nonamethylene diamine, decamethylene diamine, undecamethylene diamine, dodecamethylene diamine, 2, 2, 4 -Aliphatic amines such as totimethylhexamethylenediamine and 2,4,4-tochimethylhexamethylenediamine, 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 paraxylylenediamine.
Specific examples of the dicarboxylic acid include aliphatic dicarboxylic acids such as glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, nonanedioic acid, decanedioic acid, undecanedioic acid, and dodecanedioic acid, hexa Hydroterephthalic acid, alicyclic carboxylic acid such as hexahydroisophthalic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid (1,2-isomer, 1,3-isomer, 1,4-isomer, 1,5-isomer, 1,6-isomer, 1,7-isomer, 1,8-isomer, 2,3-isomer, 2,6-isomer, 2,7-isomer), and aromatic dicarboxylic acids such as metal salts of sulfoisophthalic acid be able to.

  Specific examples of the polyamide-based resin (A) derived from a lactam having three or more members, a polymerizable ω-amino acid, a diamine and a dicarboxylic acid as described above 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 (polymetaxylylene 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, Amide 6,6-6I, polyamide 6T-6I, polyamide 6,6-6T-6I and the like. These polyamide resins may be homopolymers, copolymers or mixtures thereof. Of 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-based resin (A) is JIS K6920-2 in view of miscibility between the polyamide-based resin (A) and the inorganic fillers (B) and (C), and thus forming a thin surface layer and transparency. : 2009 (solvent: 96% sulfuric acid) The relative viscosity measured according to the formula 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-based 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 film when forming a surface layer or coextruding with another layer.

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

Here, the volume cumulative distribution of the particle diameter will be described.
In general, the size of powder, which is a particle as an aggregate, is expressed as a distribution of abundance ratios for each particle size, that is, a particle size distribution. The reference of the existence ratio includes a case where a volume reference (volume distribution) is used and a case where a number reference (number distribution) is used. The volume distribution is measured by a laser diffraction / scattering method. In addition, the particle size distribution may represent the frequency at each particle size, or may represent the frequency cumulatively with respect to the particle size. FIG. 1 shows an example of a cumulative distribution diagram of particle diameters.
The 50% diameter (d50) in the cumulative volume distribution means that, in the cumulative volume distribution of the particle diameter, when the powder is divided into a large particle diameter side and a small particle diameter side at a certain particle diameter, This is the diameter at which the distribution and the distribution on the smaller side are 50% of the same amount. Similarly, the 10% diameter (d10) is the diameter at which the smaller side becomes 10%, and the 90% diameter (d90) is the diameter at which the smaller side becomes 90%. Therefore, the difference between the 90% diameter (d90) and the 10% diameter (d10) means the breadth of the particle size distribution, and the larger the difference, the more the primary particles having different particle diameters.

In this film, in order to combine good slipperiness under high humidity and the appearance and transparency of the film, as an index of the particle diameter for forming fine protrusions on the surface layer, not just an average particle diameter, It became clear that the distribution of the particle size is essential, and the 50% size, 10% size, and 90% size in the volume cumulative distribution of the particle size were specified.
Moreover, it turns out by using together the inorganic fillers (B) and (C) from which a particle size distribution index differs, and it turns out that transparency and slipperiness under high humidity improve greatly, and in volume cumulative distribution of each particle size The 50% diameter, 10% diameter, and 90% diameter were specified. The inorganic filler (C) specified as such has an effect of mainly imparting slipperiness to the film, and the inorganic filler (B) has a particle diameter including a wide range from relatively small to large particles. Further, it has the effect of complementing the slipperiness by the inorganic filler (C) and imparting high transparency to the film.

<Inorganic filler (B)>
The inorganic filler (B) contained in the surface layer of the 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 and 0.005. 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. Further, 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.

If the 50% diameter (d50) is in the above range, it is an appropriate size that is too large and does not cause deterioration of transparency of the film or printing failure. If the 10% diameter (d10) is in 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 If it is the said range, when a polyamide-type resin (A) and an inorganic filler are compounded with a twin-screw extruder, for example, the secondary aggregation of an inorganic filler will collapse | crumble and it will form a suitable protrusion for providing the slipperiness of a film. easy.
In addition, when the inorganic filler (B) is used in combination with the inorganic filler (C) having a different particle size distribution index, the transparency and 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 excellent in slipperiness can be obtained, and is in the form of powder, particles, flakes, plates, fibers, needles. , A cloth shape, a mat shape, or any other shape may be used, but a particulate shape is preferable. Even in the form of particles, if the shape is spherical or cubic, even if strong shearing occurs during kneading into the resin, it will be dispersed in the resin without breaking the shape, improving the slipperiness of the film surface Since it is easy to make it, it is preferable.

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 within a range, for example, when the surface treatment is performed with a surface treatment agent such as a silane coupling agent, the compatibility with the polyamide resin is improved 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-based resin (A) is improved, which is a matrix. In the polyamide resin (A), the inorganic filler is easily dispersed, the generation of coarse particle aggregation can be suppressed, and even when biaxially stretching to obtain the present film, void formation and transparency Deterioration and omission during printing can be suppressed. Moreover, if a specific surface area is 1 m < ² > / g or more, a primary particle does not become a coarse monodisperse particle and is preferable.

  Specific examples of the inorganic filler (B) include silica such as gel type silica, precipitated type silica and spherical silica, talc, kaolin, montmorillonite, zeolite, mica, glass flake, wollastonite, potassium titanate, magnesium sulfate, 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 a volume cumulative distribution by a laser diffraction method. 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. Further, the lower limit of the 10% diameter (d10) is preferably 0.4 μm or more, and more preferably 0.5 μm or more. The upper limit of the difference between the 90% diameter (d90) and the 10% diameter (d10) is preferably 3 μm or less, more preferably 2 μm or less, and the lower limit is preferably 1.0 μm or more.

If the 50% diameter (d50) and 10% diameter (d10) of the volume cumulative distribution are in the above range, fine protrusions that do not affect the transparency can be formed on the film surface, and the 90% diameter (d90). And the 10% diameter (d10) difference is within the above range, even if the secondary aggregate of particles is present, the aggregation is broken by the film extruder, and projections 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, transparency and 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 excellent in slipperiness can be obtained, and is in the form of powder, particles, flakes, plates, fibers, needles. , A cloth shape, a mat shape, or any other shape may be used, but a particulate shape is preferable. Even in the form of particles, if the shape is spherical or cubic, even if strong shearing occurs during kneading into the resin, it will be dispersed in the resin without breaking the shape, improving the slipperiness of the film surface Since it is easy to make it, it is preferable.

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, and 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 within a range, for example, when the surface treatment is performed with a surface treatment agent such as a silane coupling agent, the compatibility with the polyamide resin is improved 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 biaxially stretching to obtain the present film, formation of voids and deterioration of transparency can be suppressed. At the same time, aggregation of fillers can be suppressed, and large protrusions that cause printing omission are not formed on the film surface, and the printability is good. Moreover, if a specific surface area is 1 m < ² > / g or more, a primary particle does not become a coarse monodisperse particle and is preferable.

  Specific examples of the inorganic filler (C) include silica such as gel type silica, precipitated type silica, spherical silica, talc, kaolin, montmorillonite, zeolite, mica, glass flake, wollastonite, potassium titanate, magnesium sulfate, 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 the film are surface-treated. By covering the surface of the inorganic filler with a suitable surface treatment agent, the compatibility with the polyamide-based resin (A) that is the matrix is improved, and the dispersibility of the inorganic filler is improved. Therefore, even when the film is stretched, for example, whitening due to voids and generation of coarse protrusions that cause printing omission due to filler aggregation can be suppressed, and printing omission when gravure printing is performed. There is no problem.

  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 alkoxysilane compounds 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 are excellent in affinity between the polyamide-based resin (A) and the above-described 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, γ-dibutylaminopropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, γ-ureidopropyltrimethoxysilane, γ- (2-ureidoe Tyl) Ureido group-containing alkoxysilane compounds such as aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxy Epoxy group-containing alkoxysilane compounds such as silane, γ-mercaptopropyltrimethoxysilane, mercaptogroup-containing alkoxysilane compounds such as γ-mercaptopropyltriethoxysilane, γ-isocyanatopropyltriethoxysilane, γ-isocyanatopropyltrimethoxy Silane, γ-isocyanatopropylmethyldimethoxysilane, γ-isocyanatopropylmethyldiethoxysilane, γ-isocyanatopropylethyldimethoxysilane, γ-isocyanatopropylethyldiethoxysilane Examples thereof include lanthanum, isocyanato group-containing alkoxysilane compounds such as γ-isocyanatopropyltrichlorosilane, 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, γ-aminopropyltriethoxysilane, and γ -Glycidoxypropyltrimethoxysilane, 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 preferred, and 3-aminopropyl-triethoxysilane is particularly preferred.

  The method of surface-treating the inorganic fillers (B) and (C) with the surface treatment agent is not particularly limited. For example, the surface treatment agent or the surface treatment agent solution is added dropwise or sprayed to the inorganic filler particles, and Henschel is added. After stirring uniformly with a suitable device such as a mixer, and then drying at a predetermined temperature, or by dispersing inorganic filler particles in water or the like to form a slurry and stirring the surface treatment agent In addition, a wet processing method in which dehydration and drying are performed thereafter can be given.

  The addition concentration of the surface treatment agent during the surface treatment is preferably 0.1 to 20% by mass with respect to each of the inorganic fillers (B) and (C), and is 0.2 to 15% by mass. More preferably, it is more preferably 0.5 to 10% by mass. When the addition of the surface treatment agent is less than 0.1% by mass, the affinity between the inorganic filler and the polyamide-based resin (A) is not sufficient, and the dispersibility is deteriorated. On the other hand, even if added in a large amount exceeding 20% by mass, the effect of improving the dispersibility is hardly increased, and the mechanical properties of the film are impaired, and problems such as bleeding out of the surface treatment agent to the film occur. .

<Combination of inorganic fillers (B) and (C)>
In the present invention, by using the two kinds of inorganic fillers (B) and inorganic fillers (C) having different particle size distribution indexes, the transparency is excellent and the slipping property is greatly increased even under high humidity. An improved film can be obtained, and the effect can be obtained even if the film surface layer is thinned 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 print omission and corona treatment do not occur. That is, the blending of the inorganic fillers (B) and (C) has such various good characteristics and can satisfy the required quality of the packaging film.

The content of the inorganic filler (B) and inorganic filler (C) in the surface layer of the film is such that the final film has excellent slipperiness and optical properties such as transparency and surface glossiness. It should be within a range where 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 mass% or more and 0.50 mass% or less as a 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 composition constituting the surface layer. It is preferable that it is 0.05 mass% or more and 0.40 mass% or less, and it is more preferable that it is 0.10 quality% or more and 0.30 mass% or less. If the content ratio is 0.01% by mass or more, the effect of improving the slipperiness of the obtained film is sufficient. On the other hand, if the content ratio is 0.50% by mass or less, the transparency and appearance of the film are impaired. It is preferable that the film surface has too many irregularities, and printing omission and corona treatment failure 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 in the composition of the surface layer. Moreover, the formed film fractionates the surface layer and ashes it, whereby the total mass of the inorganic filler 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 still more preferably 1: 3 to 1: 1. By containing together the inorganic fillers (B) and (C) having different particle size distribution indexes at such a ratio, it is possible to combine good transparency and slipperiness under high humidity.

  Mixing of the polyamide-based resin (A), the inorganic filler (B), and the inorganic filler (C) is performed by mixing the polyamide-based resin (A) in a pellet state, more preferably in a powder state, or a raw material thereof, and the inorganic filler particles. A method in which a predetermined amount is blended at room temperature using a high-speed rotary mixer such as a Henschel mixer or a low-speed rotary mixer such as a cone blender or tumbler used for normal mixing, or the blend is further mixed with a Banbury mixer, super Use equipment such as a mixer, mixing roll, twin-screw continuous mixer, Brabender plastograph, kneader, single-screw extruder, twin-screw extruder, etc., and melt at a temperature at which the blend melts sufficiently and does not decompose Although it is carried out by a method known per se such as a kneading method, the one kneaded in a twin screw extruder is the master. How to batching is desirable. Two types of inorganic fillers, the inorganic filler (B) and the inorganic filler (C), may be added simultaneously or separately.

<Organic lubricant>
The surface layer of the film may further contain a fatty acid amide as an organic lubricant. Specific examples of the fatty acid amide include, for example, behenic acid amide, stearic acid amide, montanic acid amide, erucic acid amide, hydroxy stearic acid amide, oleic acid amide, ricinoleic acid amide, N-stearyl stearic acid amide, methylol stearic acid amide. Monoamide compounds such as ethylene bislauric acid amide, ethylene bis stearic acid amide, ethylene bishydroxy stearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene bisoleic acid amide, N, N-distearyl isophthalic acid amide, etc. And bisamide compounds. Of these, ethylenebisstearic 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 composition constituting the surface layer. More preferably, it is 0.2 mass% or less. If it is in this range, the slipperiness of the film will be good even at room temperature and under high humidity.

<Other ingredients>
The surface layer of the present film may further contain other resins as appropriate within the range not impairing the effects of the present invention.
Each layer of this film is within the range not impairing its physical properties, further heat stabilizer, antioxidant, ultraviolet absorber, weathering agent, lubricant, filler, nucleating agent, plasticizer, foaming agent, antiblocking agent, An anti-clouding agent, a flame retardant, a dye, a pigment, a stabilizer, a coupling agent, an impact resistance improving material, and the like can be appropriately contained.

<Structure of this film>
The structure of this film is a multilayer film, as long as it has at least one surface layer containing the above-mentioned polyamide-based resin (A), inorganic filler (B), and inorganic filler (C), and the number of layers is not limited. The layer structure can be appropriately combined with other layers as necessary. The other layers may be at least one layer, and a plurality of layers of two or more layers may be laminated as 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.
Moreover, it is more preferable to have the surface layer of the said composition on both surfaces of a film at the point of winding of the roll of this film, and the slipperiness of unwinding, and it is useful at the time of the secondary process using this film.

  Specific examples of the resin constituting the other layers include polyethylene, ethylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid. Ethylene resins such as ester copolymers, propylene resins such as polypropylene and 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 copolymer. Moreover, in order to improve the interlayer adhesiveness of each layer, you may arrange | position an adhesive layer as needed.

As a preferred configuration example of the film, the middle layer is mainly composed of a polyamide-based resin (polyamide MXD6 resin) having a gas barrier property mainly composed of polymetaxylylene adipamide or the like, or an ethylene-vinyl alcohol copolymer. The structure which arrange | positioned the resin layer which has gas barrier property to arrange | position, and arranged the polyamide-type resin layer of this invention as a surface layer can be mentioned.
In addition, an adhesive layer, a sealant, a metal foil, paper, or the like can be further laminated on the film by a dry lamination method, a wet lamination method, a sand lamination method, an extrusion lamination method, or the like as necessary.
Moreover, this film can also perform surface treatment and surface processing, such as corona treatment, printing, coating, and vapor deposition, as necessary.

<Method for producing this film>
Although the manufacturing method of this film will not be specifically limited if it can be used as a multilayer film, A coextrusion method is preferable and a coextrusion multilayer extending | stretching method is more preferable. For example, an unstretched multilayer film coextruded with a feed block or a multi-manifold die may be manufactured, and a biaxially stretched film by a tenter simultaneous biaxial stretching method may be manufactured. Moreover, it is good also as a stretched film by the sequential biaxial stretching method which extends | stretches in a vertical direction with a roll type longitudinal stretch machine, and is laterally stretched with a tenter type stretcher. Furthermore, it is also possible to implement a tubular stretching method in which a tubular sheet formed from an annular die is stretched simultaneously in the longitudinal and lateral directions by a gas pressure. The stretching step may be carried out continuously after the production of the unstretched film, or the unstretched film may be wound up once and carried out as a separate step.

The draw ratio is preferably 1.5 to 5 times, more preferably 2 to 4 times in both the longitudinal direction and the transverse direction. The stretching temperature is preferably 30 to 220 ° C, and more preferably 40 to 200 ° C.
After the stretching step, the end portion is continuously held with a tenter clip, and at a temperature of 200 ° C. or higher and the melting start temperature of the polyamide resin (A) + 10 ° C. or lower in a tenter oven, about 1 second to 2 minutes, preferably 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 the film is not particularly limited, but is generally about 1 μm or more and 15 μm or less. In addition, even if it is a thin surface layer, this invention is characterized by the point which has the remarkable effect that it is excellent in transparency and is excellent also in the slipperiness under high humidity, for example, 10 micrometers or less, Furthermore, it was referred to as 5 micrometers or less Even in the case, a sufficient effect can be exhibited.
Further, the total thickness of the film is not particularly limited, but for example, when considering workability and practicality, 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 is preferably 50 μm or less, and more preferably 30 μm or less. If the total thickness of the film is within the above range, the film has sufficient rigidity and excellent mechanical properties such as pinhole resistance and impact resistance.

<Physical properties 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, and even more preferably less than 4.5%. When the total haze value is within the range, the film has particularly excellent transparency, good appearance, and good visibility of the package contents.

(2) Sliding property This film preferably has a static friction coefficient and a dynamic friction coefficient both of less than 0.50 measured under conditions of 23% relative humidity and 50% based on JIS K7125, and is 0.40 or less. Is more preferable, and 0.35 or less is more preferable.
Moreover, although this film has a polyamide resin as a main component of the surface layer, the present film exhibits an excellent effect that the slipperiness under high humidity is good. 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 both preferably less than 0.50, more preferably 0.40 or less, and even more preferably 0.35 or less. .
If the values of the static friction coefficient and the dynamic friction coefficient are within such ranges, the film will be particularly excellent in slipperiness, and blocking will not easily occur in steps such as winding, slitting and rewinding during film production. Polyamide-based resin films have good tensile elongation, tensile strength, and pinhole resistance, and are widely used for liquid-filled packaging applications. From the feature that it is good, blocking trouble does not occur, and further high-speed filling is possible, which is effective for improving the packaging production efficiency.

(3) Secondary workability Since this film has moderate surface irregularities formed by inorganic fillers, for example, it is difficult to cause defects in corona treatment, missing dots in gravure printing, etc., and good secondary processing of the film. Can be done.

<Use of this film>
The film is excellent in transparency, slipperiness, mechanical properties, etc., and is not particularly limited as long as it is used for such quality. For example, for food packaging, 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. In particular, the film can be suitably used for boil / retort food packaging, various vacuum packaging, and the like.

<Packaging body using this film>
This film can be made into a package by performing bag making processing or the like. The shape of the package is not particularly limited. For example, two-sided seal bags, three-sided seal bags, jointed bags, gusset bags, stand bags, side seal bags, bottom seal bags, and other packaging bags, containers, containers, etc. For example.

  Examples are shown below, but the present invention is not limited by these. In addition, the various measured value and evaluation about the raw material and test piece which are displayed in this specification were performed as follows.

<Evaluation method>
(1) Total haze About the film obtained in the Example, the value (%) of the film of thickness 18 micrometers was measured based on JISK7136: 2000.

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

(3) Printability About the film obtained in the Example, gravure printing was performed using a gravure printing plate having a cell pitch of 100 μm and a gradation of 30%. For the ink, Toyo Ink's “Rio Alpha S R39 Ai” and special No. Two solvents were used and the viscosity was adjusted to 17 seconds with Zahn cup # 3. Next, 10 points of 15 mm × 30 mm in size were cut out from the printed film, and the places where printing without ink was lost were counted. The case where the average of the number of printing missing points of 10 points was 20 or less was evaluated as “◯”, and the case of 21 points or more was evaluated as “X”.

(4) Gas barrier property About the film obtained in the Example, based on JIS K7126-2 method, the oxygen permeability (cc / m < ² > / 24h / atm) in the conditions of the atmosphere of 23 degreeC relative humidity 50% is measured. did.

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

In the following inorganic fillers (B) and (C), “d50”, “d10”, and “d90” are 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.
Resin in which polyamide-based resin (A), inorganic filler (B), and (C) are mixed in the content ratios shown in Table 1 in the first layer and the fifth layer, which are the surface layers, in the production of the five-layer multilayer film The composition was used. (A) -1 was used for the second layer, the third layer, and the fourth layer.
For the film, a single-layer extruder with a diameter of 40 mm was used for the first layer and the fifth layer, and a single-screw extruder with a diameter of 32 mm was used for the second layer, the third layer, and the fourth layer. 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 machine direction by a roll-type stretcher under the condition of 55 ° C., and then the end of the longitudinally stretched film was held with a tenter clip, and 120 ° C. in a tenter oven. The film was stretched 3.5 times in the transverse direction under the conditions described above, and then heat-fixed at 220 ° C. to perform 7% transverse relaxation. Then, it cooled to room temperature, the both ends corresponding to the holding part of a clip were trimmed, and the multilayer stretched film after trimming was wound up in roll shape.
The thickness of each of the obtained five-layer stretched films is such that the first layer and the fifth layer (surface layer) are about 4.2 μm, the second layer and the fourth layer are about 2.4 μm, and the third layer (middle layer) is about The total thickness was 4.8 μm and about 18 μm.
Table 1 shows the results of evaluating 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 obtained by subjecting (s) -2 to surface treatment with (s) -2 at a concentration of 0.5% by mass to (c) -1 was used. 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 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 evaluated.

(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 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 evaluated.

(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 evaluated.

(Example 13)
A multilayer film was obtained and evaluated in the same manner as in Example 1 except that (b) -3 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 in the same manner as in Example 1 except that (b) -4, which was surface-treated with (s) -1 at a concentration of 5% by mass as the inorganic filler (B), was evaluated. .

(Comparative Example 1)
A multilayer film was obtained and evaluated in the same manner as in Example 1 except that the inorganic filler (C) was not used and the content of the inorganic filler (B) was changed to the ratio shown in Table 1.

(Comparative Example 2)
A multilayer film was formed in the same manner as in Example 1 except that (b) -1 and (b) -2, which were each 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 inorganic filler (B) was not used and the content of the inorganic filler (C) was changed as shown in Table 1.

(Comparative Example 4)
As inorganic filler (C), (c) -1 surface-treated with (s) -1 at a concentration of 0.5% by mass, (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 was used for evaluation.

(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 evaluated.

(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 evaluated.

(Comparative Example 7)
A multilayer film was obtained and evaluated in the same manner as in Example 1 except that (b) -5 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. Others were obtained in the same manner as in Example 1 and evaluated.

(Comparative Example 10)
A multilayer film was obtained in the same manner as in Example 1 except that (b) -1 and (c) -1 that were not subjected to surface treatment were used as the inorganic fillers (B) and (C), and evaluation was performed. Went.

  The films of Examples 1 to 14 had a haze of 5.0% or less, a static friction coefficient and a dynamic friction coefficient satisfying less than 0.50 in any conditions, and good printability. Furthermore, 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 satisfied 0.35 or less under any condition, and 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 ^{0.8cc / m 2 / 24h / atm} , in the fourth embodiment the third layer component is a polyamide MXD resin ^{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 filler was high, the haze was high, and printing omission occurred.
In Comparative Examples 7 and 8, the specific surface area of the inorganic filler was large, the haze was high, and printing omission occurred.
In Comparative Example 9, the surface treatment agent for the inorganic filler was sodium stearate, the haze was high, the friction coefficient was high under high humidity, and printing omission occurred.
In Comparative Example 10, an inorganic filler not subjected to surface treatment was used, haze was high, and printing omission occurred.

  The multilayer film of the present invention has a good balance between transparency and slipperiness even in a thin surface layer, has good slipperiness even under high humidity, and has troubles in post-processing such as print omission and poor corona treatment. Since it does not generate | occur | produce, it can use suitably for the various film for packaging for which thickness reduction is requested | required. Moreover, since the food hygiene standard is also satisfied, it can be suitably used for food packaging applications.

1; surface layer, first layer 2; middle layer, second layer 3; surface layer, third layer 10; multilayer film 11; surface layer, first layer 12; middle layer, second layer 13; middle layer, third layer 14 Intermediate layer, fourth layer 15; surface layer, fifth layer 20; multilayer film

Claims (6)

In the thermoplastic resin multilayer film,
At least one of the surface layers is mainly composed of the polyamide-based resin (A), includes inorganic fillers (B) and (C),
The particle size of the inorganic filler (B) is such that the 50% diameter (d50) in the volume cumulative distribution by the laser diffraction method is 1 μm or more and 6 μm or less, and the 10% diameter (d10) is 0.1 μm or more and 0.5 μm or less, The difference between the 90% diameter (d90) and the 10% diameter (d10) is 5 μm or more and 10 μm or less,
As for the particle diameter of the inorganic filler (C), the 50% diameter (d50) in the volume cumulative distribution by the laser diffraction method is 1.5 μm or more and 3.5 μm or less, and the 10% diameter (d10) is 0.3 μm or more and 1.0 μm. The difference between the 90% diameter (d90) and the 10% diameter (d10) is 0.5 μm or more and 5 μm or less,
Each of the inorganic fillers (B) and (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.
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 in an environment of 23 ° C and a relative humidity of 80% are both less than 0.50.   The multilayer film according to any one of claims 1 to 3, wherein the haze is 5.0% or less.   5. The coextruded multilayer stretched film according to claim 1, wherein the thermoplastic resin multilayer film has an intermediate layer mainly composed of polyamide MXD6 (polymetaxylylene adipamide) resin or ethylene-vinyl alcohol resin.   The package using the multilayer film in any one of Claims 1-5.

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