JPH10168309A - Polyamide film having excellent slipperiness - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject film having excellent slipperiness under high- humidity condition while keeping the transparency and surface gloss of the film by forming protrusions having a specific size on a polyamide film surface at a specific density. SOLUTION: This polyamide film has a surface roughness characterized by the presence of 6-30/mm of protrusions having a height of >=0.06μm from the center line measured by a surface-roughness tester, a haze value of ≃1.0% and a glass of >110. The film can be produced by compounding a polyamide resin with a surface-roughening substance, especially inorganic fine powder, concretely a gel-type silica, etc., forming the composition in the form of a film and drawing the film at an areal draw ratio of >=3. Preferably, >=50wt.% of the polyamide resin is a poly-ε-capramide or a copolymer containing the recurring structural unit of poly-ε-capramide as a main component.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a polyamide film having excellent slipperiness. More specifically, the present invention relates to a polyamide film having excellent slipperiness while maintaining transparency and surface gloss by forming projections of a specific size at a specific existence density on the film surface, in particular, under high humidity. .

[0002]

2. Description of the Related Art Polyamide films are widely used mainly in the field of food packaging because of their excellent properties such as transparency, pinhole resistance, gas barrier properties, heat resistance and oil resistance. In such a field, the slip property of the packaging film is an important property, and poor slip property not only causes troubles in post-processing steps such as a laminating step and a printing step, but also causes a problem in the final packaging step. In this case, the supply of the film does not proceed smoothly, and defective packaging occurs.
Particularly, in the packaging of foods containing a large amount of water, slipperiness under high humidity is regarded as important because the food is used in a high humidity environment.

However, in general, polyamide films, particularly polyamide films containing nylon 6 as a main component, are poor in slipperiness under high humidity, and improvement is required. Therefore,
In order to improve the slipperiness of a polyamide film, for example, the formation of surface projections by adding an inorganic filler (Japanese Unexamined Patent Publication No.
JP-A-252452, JP-A-63-251460, JP-A-1-156333, etc.) and formation of surface projections by dispersing other resins (JP-A-62
-294526, JP-A-1-92235, etc.), formation of projections during film forming or post-processing (JP-B-51-7708, JP-A-5-42)
No. 782, etc.) and a method of roughening the film surface such as coating of the film surface with a projection-forming substance (see Japanese Patent Application Laid-Open No. 55-95571, etc.), or a method of adding an organic lubricant ( JP-A-3-7
Various methods have been tried, such as 9634 and JP-A-8-73626.

[0004]

However, among the above-mentioned means for improving the slipperiness, the method using an inorganic filler is the easiest and most effective in forming minute projections on the film surface. However, the effective addition amount is different depending on the effect, and the effect varies, and it is not a completed technology. That is, if the added amount of the inorganic filler is small, sufficient slipperiness cannot be obtained, and if the added amount is too large, the transparency and surface gloss of the film are significantly reduced, and the commercial value as a packaging film is lost. Due to such a problem, a polyamide film having slipperiness, particularly sufficient slipperiness under high humidity, has not been obtained. In addition, in other surface roughening methods such as forming surface projections by dispersing other resin, forming projections during film forming or post-processing, and coating a film-forming substance on the film surface, the inorganic filler may be used. The establishment of surface projections effective for improving slipperiness, especially under high humidity, while maintaining properties such as optical properties such as transparency and glossiness of the film, similar to the method by adding There was no technology. On the other hand, in order to obtain sufficient lubricity by the method of adding an organic lubricant, a large amount of addition is required, and slippage such as poor biting in an extruder during melt molding and poor printability of the obtained film is caused. However, the technique for producing a polyamide film having sufficient properties, especially sufficient slipperiness under high humidity, was insufficient.

Accordingly, an object of the present invention is to solve such problems in the prior art, that is, to provide a polyamide film excellent in slipperiness under high humidity while maintaining the transparency and surface gloss of the film. Is to do.

[0006]

Means for Solving the Problems Accordingly, the present inventors have:
As a result of intensive studies to solve the above-mentioned problems in the polyamide film, it was found that the above object can be achieved by forming protrusions of a specific size at a specific existence density on the surface of the polyamide film, and completed the present invention. That's what happened.

That is, the first invention of the present invention is:
In the surface roughness measurement, the number of protrusions having a height of 0.06 μm or more from the center line is 6 to 30 / mm, the haze is 10% or less, and the gloss is greater than 110. Can be achieved by providing a polyamide film having excellent slipperiness under high humidity. The second invention according to the present invention relates to the first invention obtained by stretching a raw polyamide film formed by molding a composition obtained by blending a roughening substance with a polyamide resin at an area ratio of three times or more. This can be achieved by providing a polyamide film. Further, a third invention according to the present invention relates to the polyamide film according to the second invention, wherein the surface roughening substance is inorganic fine particles, and a fourth invention according to the present invention, wherein 50% by weight or more of the polyamide resin is used. The present invention can be achieved by providing the polyamide film according to the second or third invention, which is a poly-ε-capramide or a copolymer containing a repeating structural unit of poly-ε-capramide as a main component, respectively.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The polyamide resin used in the present invention may have any structure and composition as long as it is generally known as a polyamide and can form a film. However, when a polyamide resin having a large decrease in slipperiness under high humidity in a film state is used, the obtained polyamide film has excellent slipperiness under high humidity while maintaining its transparency and surface gloss. The effect of the present invention is remarkable. Here, “under high humidity” means that an atmosphere with a relative humidity of 60% is a normal state and an atmosphere with a relative humidity higher than that is used. Specifically, an atmosphere state where the relative humidity exceeds 70% Means below.
Hereinafter, in the present invention, “under high humidity” is used in this sense. The polyamide resin used in the present invention includes the following formula (I)

[0009]

Embedded image

Polyamides comprising a poly-ε-capramide repeating structural unit represented by the formula or polyamides containing the poly-ε-capramide repeating structural unit as a main component. Poly-ε- represented by the above formula (I)
The polyamide comprising a capramid repeating structural unit is, specifically, poly-ε-capramide obtained by ring-opening polymerization of ε-caprolactam or polycondensation of aminocaproic acid, that is, nylon 6.

On the other hand, poly-ε- represented by the above formula (I)
Examples of the polyamide containing a capramide repeating structural unit as a main component include the nylon 6 and a lactam having three or more members, a polymerizable ω-aminocarboxylic acid, a dicarboxylic acid and a diamine, and a salt obtained from the dicarboxylic acid and a diamine. Copolymers with polyamide obtained by polycondensation are exemplified. And, as a lactam having three or more members, for example, ω-enantholactam, ω-undecane lactam,
ω-dodecalactam, α-pyrrolidone, δ-methylpyrrolidone, α-piperidone and the like. As a polymerizable ω-aminocarboxylic acid, for example,
ω-aminoheptanoic acid, ω-aminononanoic acid, ω-aminoundecanoic acid, ω-aminododecanoic acid, and the like.

The dicarboxylic acids include, for example, succinic acid, glutaric acid, adipic acid, 2-methyladipic acid, 3-methyladipic acid, 3-t-butyladipic acid, pimelic acid, suberic acid, azelaic acid, Aliphatic dicarboxylic acids such as sebacic acid, nonandionic acid, decanedioic acid, undecandioic acid, dodecandionic acid, tridecandioic acid, tetradecandionic acid, pentadecandionic acid, hexadecandionic acid and eicosandioic acid, hexahydroterephthalic acid, hexa Alicyclic dicarboxylic acids such as hydroisophthalic acid and hexahydrophthalic acid, and terephthalic acid, isophthalic acid, 5-t
-Butyl isophthalic acid, 1,2-naphthalenedicarboxylic acid, 1,3-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid,
1,6-naphthalenedicarboxylic acid, 1,7-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,
3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,3-
Anthracene dicarboxylic acid, 1,4-anthracene dicarboxylic acid, 1,5-anthracene dicarboxylic acid, 1,9
-Anthracene dicarboxylic acid, 2,3-anthracene dicarboxylic acid, 9,10-anthracene dicarboxylic acid, biphenyl-2,2'-dicarboxylic acid, biphenyl-2,
Aromatic dicarboxylic acids such as 3′-dicarboxylic acid and 3- (4-carboxyphenyl) 1,1,3-trimethyl-5-indanecarboxylic acid can be mentioned.

As the diamine, for example, ethylenediamine, propylenediamine, tetramethylenediamine,
Pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, 2,2,4
-Trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, 2-methylhexamethylenediamine, 3-methylhexamethylenediamine,
Aliphatic diamines such as 2-ethyloctamethylenediamine and 3-t-butylhexamethylenediamine;
3-diaminocyclohexane, 1,4-diaminocyclohexane, 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) cyclohexane, isophoronediamine, piperazine, N-aminoethylpiperazine, 2,5-dimethyl Piperazine, bis (4-aminocyclohexyl) methane and 2,2-bis- (4 ′
-Aminocyclohexyl) propane and the like, and aromatic diamines such as meta-xylylenediamine and para-xylylenediamine.

Accordingly, as the polyamide containing as a main component the poly-ε-capramide repeating structural unit represented by the above formula (I) used in the present invention, specifically, nylon 4/6 copolymer, nylon 6 / 7 copolymer, nylon 6/8 copolymer, nylon 6/9 copolymer, nylon 6/11 copolymer, nylon 6/12 copolymer, nylon 6/46 copolymer, nylon 6/66 Copolymer, nylon 6/69 copolymer, nylon 6/61
0 copolymer, nylon 6/611 copolymer, nylon 6
/ 612 copolymer, nylon 6/66/610 terpolymer, nylon 6/66/611 terpolymer, nylon 6/66/612 terpolymer, nylon 6/66 /
Binary or ternary copolymers of nylon 6 with aliphatic homopolyamide or copolyamide, such as 11 terpolymer and nylon 6/66/12 terpolymer, nylon 6 and polyhexamethylene Phthalamide (nylon 6T), polyhexamethylene isophthalamide (nylon 6I), polymethaxylylene adipamide (nylon MX
D6), polymetaxylylene veramide (nylon MX)
D8), polymethaxylylene sebacamide (nylon MX
D10), nylon 6T / 6I copolymer, meta-xylylene / para-xylylene adipamide copolymer, meta-xylylene / para-xylylene pimeramide copolymer, meta-xylylene / para-xylylene azeramide copolymer, meta-xylylene / para-xylylene Binary or ternary copolymers with semi-aromatic homopolyamides or copolyamides such as rensebacamide copolymers and metaxylylene / paraxylylene adipamide / sebacamide copolymers, and nylon 6/66 / 6T ternary Copolymer, nylon 6/66 / 6I
Terpolymer, nylon 6/11 / 6T terpolymer,
Nylon 6/11 / 6I terpolymer, nylon 6/1
Tertiary copolymers of nylon 6 and an aliphatic-semi-aromatic copolyamide, such as a 2 / 6T terpolymer and a nylon 6/12 / 6I terpolymer, and the like. In the present invention, the polyamide comprising the above-mentioned poly-ε-capramide repeating structural unit, that is, nylon 6, or a polyamide containing a poly-ε-capramide repeating structural unit as a main component, economical efficiency and easy availability. In consideration of the above, nylon 6, nylon 6/66 copolymer, nylon 6/12 copolymer, nylon 6/66/12 terpolymer, nylon 6 / 6T copolymer, nylon 6 / 6I
Copolymers, nylon 6 / MXD6 copolymers and the like are preferred.

The polyamide resin used in the present invention, that is, a polyamide containing nylon 6 or a poly-ε-capramide repeating structural unit as a main component, comprises:
It may be used alone or in a blend with another polyamide resin, or may be used in combination with another thermoplastic resin in a small amount that does not impair the object of the present invention. However, the content of the nylon 6 component in the polyamide containing the poly-ε-capramide repeating structural unit as a main component, that is, the poly-ε-capramide repeating structural unit represented by the formula (I) is 60% by weight or more. , Preferably 70% by weight or more. further,
The amount of the polyamide containing the above-mentioned nylon 6 or poly-ε-capramide repeating structural unit as a main component in the polyamide resin used in the present invention is preferably at least 50% by weight, more preferably at least 70% by weight.
When the amount of the polyamide containing the nylon 6 or the poly-ε-capramide repeating structural unit as a main component is less than 50% by weight, the effect of the present invention (that is, the transparency and surface (Excellent slipperiness under high humidity while maintaining optical properties such as gloss) may not be sufficiently exhibited.

When the above-mentioned diamine and dicarboxylic acid are used as the raw materials, for example, the polyamide resin used in the present invention may be in the form of an aqueous solution or an aqueous dispersion in which approximately equivalent amounts of these components are preliminarily mixed. When using an equimolar salt of the above-described diamine and dicarboxylic acid, an ω-aminocarboxylic acid or a lactam having three or more ring members, polycondensation in an ordinary autoclave is performed in the form of an aqueous solution or aqueous dispersion of these raw materials. After producing a low-order condensate, further, the low-order condensate is melt-polymerized using a general-purpose melt kneader such as a twin-screw extruder or a twin-screw kneader, and a method of vacuum drying after pelletization, or It can be produced by a method known per se, such as a method in which solid phase polymerization is performed using a blender or a Nauter mixer or the like, followed by melt pelletization and vacuum drying. When the polyamide resin is used as a mixture with another polyamide resin or another thermoplastic resin, it contains, as a main component, the nylon 6 or poly-ε-capramide repeating structural unit obtained as described above. A polyamide resin pellet and another polyamide resin or thermoplastic resin in powder or pellet form may be mixed at a predetermined ratio by a V-type or cylindrical blender, and may be further melted and re-pelletized as necessary.

In the present invention, the finally obtained polyamide film has a surface obtained by a surface roughness measurement by a method described later using a stylus type two-dimensional surface roughness measuring device having a stylus radius of 5 μm. 0.0 from center line of roughness curve
It is necessary to have a surface roughness at which projections are formed at an existing density such that the number of projections having a height of 6 μm or more is 6 to 30 / mm, preferably 10 to 20 / mm. It is a big feature. Here, the protrusion in the present invention refers to a convex portion on the + side from the center line of the surface roughness curve obtained by measuring the surface roughness with the stylus type two-dimensional surface roughness measuring device having a stylus radius of 5 μm. . When the height of the projection is less than 0.06 μm from the center line in the surface roughness curve obtained by the surface roughness measurement, regardless of the number of the projection, the height of the finally obtained polyamide film is high. Excellent slipperiness under humidity cannot be obtained.

In the case where the density of protrusions having a height of 0.06 μm or more from the center line of the surface roughness curve obtained in the above surface roughness measurement is less than 6 / mm, the final polyamide It is not preferable because excellent slip properties under high humidity cannot be obtained in the film. On the other hand, if the density of the protrusions exceeds 30 protrusions / mm, optical properties such as transparency and surface gloss of the finally obtained polyamide film are significantly reduced, which is also not preferable. In the present invention, the existing density of the projections which has little decrease in the optical properties of the polyamide film and is excellent in the slipperiness under high humidity is in the above preferred range, that is, 10 to 20 protrusions / mm.

In the present invention, the size of the projections is not limited, but the final polyamide film is more excellent under high humidity while maintaining transparency and surface glossiness. In order to express the slipperiness, the thickness is preferably about 5 to 40 μm.

The means for forming projections on the surface of the polyamide film in the present invention is not particularly limited. Using the above-mentioned polyamide resin, any method may be used as long as the projections can be formed on the surface of the film obtained by molding by the method described later, and the film is melt-molded after mixing the roughening substance with the above-described polyamide resin. For example, a method of forming projections by steam blowing or embossed cooling rolls at the time of film forming, or a method of forming projections by using embossed rolls at the time of post-processing can be applied. Alternatively,
A method of coating the film surface with a roughening substance may be used. Among these methods, the method based on the addition of a surface-roughening substance is the easiest and preferable since no special equipment is required.

The surface roughening material used in the present invention includes:
At the time of film forming and / or stretching, if it is a substance that effectively forms fine protrusions on the polyamide film surface,
There is no particular limitation on known inorganic particles and other resins. Specific examples of the roughening substance include inorganic fine particles such as silica such as gel-type silica and spherical silica, talc, kaolin, layered silicate, and glass microbeads. Further, as a roughening substance of an organic compound, when the roughening substance itself acts as particles forming effective fine projections on the surface of the polyamide film as in the case of adding inorganic fine particles, or when the roughening substance is used. Are dispersed in the polyamide resin to affect the crystallization of the polyamide, resulting in a case where the surface of the polyamide film is roughened. Specific examples of the former include particles of a thermosetting resin such as an epoxy resin, a phenol resin, a urea resin or a silicone resin, and derivatives thereof having various substituents, and the like. Nucleating agents (eg, cyclic oligomers of nylon 6, high melting point nylons such as nylon 6T, nylon 22, etc.) and polyamides having different crystallization rates (eg, recycled nylon 6, high melting point nylons such as nylon 6T, nylon 22, etc.) ). In the present invention, the use of the inorganic fine particles is preferable among these surface-roughening substances.

The surface roughening material of the present invention must have good dispersibility in the polyamide resin when mixed with the above-mentioned polyamide resin. Poor dispersibility, agglomeration of the surface roughening material occurs, poor appearance such as reduced transparency and frequent occurrence of fish eyes in the obtained polyamide film, generation of voids during stretching, deterioration in function as a packaging film, Further, there is a possibility that productivity may be reduced in melt molding. For example, when silica such as gel-type silica or spherical silica is added, the surface roughening effect is large, but in the polyamide resin, secondary aggregation occurs to form coarse particles, and the transparency of the film is only reduced. In addition, the contamination of the dies during the melt molding is promoted to cause poor appearance of the film such as generation of a die line, so that problems such as frequent cleaning of the dies are required.
Therefore, in the present invention, the inorganic fine particles as the surface roughening material are used to improve the dispersibility of the inorganic fine particles in the polyamide resin and / or to suppress dirt contamination of a die during melt molding of a film. If necessary, the surface is treated with a surface treating agent prior to mixing with the polyamide resin. For example, when using talc as the inorganic fine particles, it is often not always necessary to apply a surface treatment agent, but when using silica such as gel-type silica or spherical silica, for the reasons described above, Normal,
It is necessary to use a surface treatment with a silane coupling agent or the like to improve dispersibility.

The type and amount of the surface treatment agent vary depending on the type of the inorganic fine particles used as the surface roughening substance, and cannot be stated unconditionally. For example, when the inorganic fine particles are the aforementioned silica, In general, a silane coupling agent having an amino group or an epoxy group can be used. Specifically, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-
Phenyl-γ-aminopropyltrimethoxysilane, N
-Β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropyltriethoxysilane, γ-aminodithiopropyltrihydroxysilane, γ- (polyethyleneamino) propyltri Methoxysilane, N-β- (aminopropyl) -γ-aminopropylmethyldimethoxysilane, N
Amino-based silane coupling agents such as-(trimethoxysilylpropyl) -ethylenediamine, γ-dibutylaminopropyltrimethoxysilane and γ-ureidopropyltriethoxysilane, or γ-glycidoxypropyltrimethoxysilane and β- ( 3,4-
Epoxy silane coupling agents such as (epoxycyclohexyl) ethyltrimethoxysilane can be mentioned. Further, a mixture of two or more of these silane coupling agents can also be used.

The amount of the surface treating agent to be added is, for example, when the surface roughening substance (inorganic fine particles) is silica such as gel type silica or spherical silica, the surface treating agent, that is, the silane coupling agent is used. The amount of addition is 1 to 10% by weight, preferably 3 to 8% by weight, based on the silica (dry matter basis). If the addition amount is less than 1% by weight, the surface-roughening substance (inorganic fine particles), that is, the above-mentioned silica, has insufficient affinity with the polyamide resin,
Dispersibility in the polyamide resin becomes poor. Conversely, if the addition amount exceeds 10% by weight, the effect of improving the dispersibility of the above-mentioned silica in the polyamide resin hardly increases even if the addition amount is increased, and the mechanical properties of the polyamide film finally obtained. Problems, such as impairing the mechanical properties. When the addition amount is in the range of 1 to 3% by weight, the dispersibility of the above silica in the polyamide resin may be deteriorated. When the addition amount is in the range of 8 to 10% by weight,
There is a tendency to impair the mechanical properties of the finally obtained polyamide film. Although the surface treatment method is not particularly limited, for example, a method of adding a predetermined amount of the surface treatment agent diluted with an appropriate amount of water to a predetermined amount of the above-mentioned silica under heating and stirring, or performing a surface treatment, A commonly used method such as a method in which the surface treating agent and the above-mentioned silica are mixed with an appropriate device such as a Henschel mixer and then heat-treated at a predetermined temperature can be applied.

In the present invention, the shape of the surface roughening substance such as the above-mentioned inorganic fine particles and organic compounds is not particularly limited.
The number of protrusions having a height of 0.06 μm or more from the center line of the surface roughness curve obtained in the surface roughness measurement using a stylus type two-dimensional surface roughness measurement device having a stylus radius of 5 μm is 6 to 30. Protrusions are formed on the surface at a density of existence such as
As long as a polyamide film excellent in slipperiness under high humidity can be obtained, it can be in the form of powder, particles, flakes, plates, fibers, needles, cloths, mats, or any other shape. However, the particles are particularly preferable.

The size and number of the projections formed on the surface of the finally obtained polyamide film depend on the average particle size and particle size distribution of the surface roughening material, the state of dispersion in the polyamide resin, and the like. You. That is, when the particle size of the roughening material is large or the dispersion is poor, large protrusions are formed on the surface of the polyamide film, and when the particle size is small, small protrusions are formed. In the polyamide film finally obtained in the present invention, when the size and height of the projections on the film surface are increased, the transparency is deteriorated, and when it is reduced, the slipperiness is liable to be deteriorated. Therefore,
In the present invention, as described above, the stylus radius is 5 μm by adding the surface roughening substance to the polyamide resin.
0.06 from the center line of the surface roughness curve obtained in the surface roughness measurement using the stylus-type two-dimensional surface roughness measurement device.
The protrusions must be formed on the surface of the polyamide film at a density such that the number of protrusions having a height of at least 6 μm is 6 to 30 / mm. The average particle size and the particle size distribution of the roughening material satisfying this condition vary depending on the type of the roughening material used, and thus vary depending on the roughening material used. Therefore, the size of the surface roughening material is not particularly limited, and any size can be used as long as the protrusions are formed at the above-described density on the surface of the polyamide film.

The amount of the surface-roughening material to be added is such that the finally obtained polyamide film has excellent slipperiness under high humidity, transparency and surface gloss as described later. Should be within a range that can maintain the optical properties of This addition amount depends on the type of the roughening substance,
It depends on the shape and size, or the degree of stretching after film formation (stretching ratio, etc.), and cannot be said unconditionally. For example, when adding inorganic fine particles as the roughening substance, As values with respect to the amount (weight) of the polyamide resin, 1500 to 8000 ppm for gel type silica having an average particle diameter of 1 to 3 μm surface-treated with the silane coupling agent, and 1 to 8000 ppm for the average particle diameter of 1 for the surface treatment with the silane coupling agent. 500 to 4000 ppm for spherical silica of 平均 5 μm, and an average particle size of 2 to 7
In the case of kaolin of μm and talc having an average particle diameter of 1 to 3 μm, the content is preferably in the range of 3000 to 8000 ppm. If the amount is less than the above range, the effect of improving the slipperiness of the finally obtained polyamide film under high humidity is small. If the amount exceeds the above range,
It is not preferable because transparency and appearance of the polyamide film are impaired.

The addition of the surface-roughening substance to the polyamide resin can be performed at any stage from the above-described process of producing the polyamide resin to the process of forming a film. For example, it may be added to the polyamide raw material before the polymerization reaction, or may be added at any time after the polymerization reaction. Furthermore, it can be added to the polyamide resin after the polymerization reaction, before molding into pellets, during molding, or after pelletization. When inorganic fine particles are used as a roughening substance and added to the polyamide raw material before the polymerization reaction, for example, when ε-caprolactam is used as a raw material and water is used as a catalyst to produce nylon 6, The inorganic fine particles surface-treated with the silane coupling agent or the like according to the above method are first dispersed in an appropriate amount of water or a 50 to 80% by weight aqueous solution of ε-caprolactam, and then added to ε-caprolactam to obtain a uniform raw material. It is desirable because it is blended. Further, a polyamide resin composition containing the surface-roughening substance at a high concentration is prepared in advance in the form of a masterbatch, and then a predetermined amount before forming this and the polyamide resin containing no surface-roughening substance into a film,
You may mix. In this case, the mixing of the polyamide resin and the surface-treated roughening material as required,
A high-speed rotary mixer such as a Henschel mixer or a cone blender or a low-speed rotary mixer such as a tumbler used for normal mixing of the polyamide resin and the predetermined amount of the surface-roughening substance in a pellet state, more preferably in a powder state. Using dry blending at room temperature, or further using the blended product such as a Banbury mixer, a super mixer, a mixing roll, a twin-screw continuous mixer, a Brabender plastograph, a kneader, a single-screw extruder, or a twin-screw extruder. It can be carried out by a method known per se, such as a method of using and melting and kneading at a temperature at which the melting of the blend sufficiently proceeds and does not decompose.

In the present invention, if necessary,
Various additives and modifiers usually blended in the resin composition, for example, heat stabilizers, ultraviolet absorbers, light stabilizers, antioxidants, antistatic agents, lubricants, antiblocking agents, tackifiers, A seal improver, an anti-fogging agent, a crystal nucleating agent, a release agent, a plasticizer, a cross-linking agent, a foaming agent, a flame retardant, a colorant (eg, a pigment, a dye) and the like may be blended. In particular, nonionic surfactants such as polyglycerin fatty acid ester, sorbitan fatty acid ester, polyethylene glycol fatty acid ester, polyoxyethylene fatty acid amide, and fatty acid alkanolamide can be used alone or in combination as the antifogging agent. When weather resistance is required, it is desirable to mix the ultraviolet absorber and the light stabilizer or a combination thereof with an antioxidant. Further, the above additives and modifiers should be blended in an amount that does not impair the purpose of the present invention, and the blending time is the same as in the case of adding the roughening substance to the polyamide resin. It can be performed at any stage as described above.

Next, in the method of adding the roughening substance, which is a means of forming projections on the surface of the polyamide film according to a preferred embodiment of the present invention, the polyamide resin and the surface treatment, if necessary, are prepared as described above. A mixture comprising the roughened substance thus obtained is obtained, and then a polyamide film can be easily manufactured by applying a conventional film forming method to the obtained mixture. As a molding method for obtaining the polyamide film of the present invention, a mixture comprising the above polyamide resin and a surface roughening material is melt-extruded from an extruder at an extrusion temperature of 220 to 300 ° C., and a casting method (T
In the case of the die method, cooling is performed on the casting roll surface, or in the case of the tubular method, cooling is performed by air or water cooling. A polyamide film can also be obtained by forming various multilayer films by coextrusion with a polyolefin or the like.

Furthermore, in the method for adding a surface roughening substance, which is a means for forming protrusions on the polyamide film surface in a preferred embodiment of the present invention, the method for forming protrusions on the film surface required for the present invention (that is, surface roughness). In the surface roughness curve obtained in the roughness measurement, it is 0.
(Projections having a height of at least 0.6 μm at an existing density of 6 to 30 protrusions / mm) can be achieved by adding a small amount of the surface roughening substance as described above. It is. That is, since the surface-roughening substance added to the polyamide resin projects on the film surface by stretching, the slip property of the obtained polyamide film, particularly the slip property under high humidity, becomes even more remarkable. .

In the above case, in order to more effectively improve the slipperiness of the polyamide film, particularly under high humidity, the stretching conditions are as follows.
Preferably, stretching at a stretching ratio of 4 times or more is required.
That is, when the stretching ratio is less than 3 times in area ratio, the surface projections required for the above-mentioned present invention cannot be effectively produced, and only when stretched to 3 times or more in area ratio, the final The addition of a small amount of a roughening substance as described above within the range that can maintain optical properties such as transparency and surface glossiness of the obtained polyamide film, effective slipperiness,
In particular, a sufficient sliding property under high humidity can be obtained. In order to ensure the appearance of the surface projections required for the present invention, stretching at a stretching ratio of 4 times or more in area ratio, particularly biaxial stretching, is desirable.

As the stretching method, an unstretched film formed by a casting method or a tubular method is used for 30 to 1 hour.
In general, the film is stretched at a stretching temperature of 80 ° C. and, if necessary, heat-fixed at a temperature of 120 ° C. or higher and a temperature lower than the melting point of the polyamide resin by 10 ° C. or lower. The stretching, particularly biaxial stretching, is not particularly limited, and is performed in a roll / tenter system in which after stretching in the longitudinal direction between two sets of pinch rolls having a speed difference, stretching is performed in the transverse direction by a tenter stretching machine. Known methods such as sequential biaxial stretching, sequential or simultaneous biaxial stretching of a tenter method, and simultaneous biaxial stretching by a tubular method (that is, an inflation method) can be applied.

In the present invention, the surface roughness obtained by the surface roughness measurement can be used as the surface roughening material without significantly lowering the optical properties such as transparency and surface glossiness of the finally obtained polyamide film. In the curve, the number of protrusions having a height of 0.06 μm or more from the center line is 6 to 30 /
When a roughening substance capable of forming protrusions on the film surface with an existing density of 1 mm is used, the above-described stretching after film formation is not necessarily required. Also, as described above, it is needless to say that the above-mentioned stretching is not required even when the surface projections required for the present invention are formed by a method other than the method of adding the surface roughening substance.

The polyamide film of the present invention obtained as described above has a surface roughness obtained by measuring the surface roughness using a stylus type two-dimensional surface roughness measuring device having a stylus radius of 5 μm on the film surface. In the height curve, the number of protrusions having a height of 0.06 μm or more from the center line is 6 to 30 / mm.
Although there are protrusions at the existing density, the transparency and the surface glossiness are less reduced as compared with those to which a conventional slipperiness improver is added, and it can be said that these optical properties are maintained as films. Specifically, the polyamide film of the present invention has a haze of 10% or less, preferably 7% or less, and a gloss value of more than 110, preferably more than 110 and 170 or less. If the haze exceeds 10% or the gloss is less than 110, the transparency of the polyamide film is poor, which is not preferable. When the gloss exceeds 170, the polyamide film tends to have poor slipperiness.

The polyamide film of the present invention is excellent in slipperiness, particularly in the above-mentioned high humidity. Here, “excellent in slipperiness (that is, good in slipperiness)” means that the sliding friction is small, and specifically, the coefficient of static friction measured by a method described later in accordance with JIS K7125. Is represented. In the above and below, "excellent in slipperiness" is used in this sense. The coefficient of static friction of a film generally varies greatly depending on the type of a mating material, measurement atmosphere (temperature and humidity), and the like. Therefore, the range of the coefficient of static friction of a polyamide film having excellent slipperiness under high humidity of the present invention is also limited. It cannot be limited unconditionally. For example, the polyamide film of the present invention,
The coefficient of static friction measured by the method described below is 23 ° C. and a relative humidity of 6 when the mating material is a polyamide film.
0.6% or less, preferably 0.5 or less at 0% (hereinafter abbreviated as “60% RH”), and 1.0 or less at 23 ° C. and 80% relative humidity (hereinafter abbreviated as “80% RH”). And when the mating material is a ferrite plate, 2
It is desirably 0.3 or less at 3 ° C. and 60% RH, preferably 0.25 or less, and 0.3 at 23 ° C. and 80% RH. When the coefficient of static friction of the polyamide film finally obtained in the present invention is out of the above-mentioned normal range, the slipperiness of the polyamide film under high humidity becomes poor, and the object of the present invention cannot be achieved. In order to reliably prevent the occurrence of this undesirable phenomenon, the polyamide film is
It should have a coefficient of static friction in the preferred range described above.

In the present invention, in order to further improve the transparency while maintaining the excellent slipperiness of the polyamide film under high humidity, the present invention is characterized in that the polyamide resin and the roughening material are mixed to further improve the transparency. The above-mentioned polyamide film layer may be a film laminated on at least one side of a thermoplastic resin film such as a polyamide resin to which the surface roughening substance is not added. That is, by making the laminated film, the thickness of the polyamide film layer of the present invention can be reduced, without deterioration of the slipperiness,
The transparency of the film as a whole can be improved. Although the thickness of the polyamide film of the present invention is not particularly limited, it is desirably 3 to 100 μm, preferably 5 to 60 μm, and when a laminated film is used, the thickness of the polyamide film layer of the present invention is preferably 0.1 to 0.1 μm. 5-
The thickness is preferably 30 μm, more preferably 1 to 20 μm.

Further, the polyamide film of the present invention comprises:
Surface treatment such as corona discharge treatment, plasma treatment, flame treatment, and acid treatment can be performed to improve printability, lamination, and adhesive application properties. Further, after such a treatment is performed as necessary, it can be used for the intended use through secondary processing steps such as printing, lamination, application of an adhesive, and heat sealing.

[0039]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, which do not limit the present invention in any way. In the following Examples and Comparative Examples, the physical properties of the polyamide resin and the polyamide film were measured by the following methods. (1) Relative viscosity of polyamide resin Measured using 98% by weight concentrated sulfuric acid according to JIS K6810-970.

(2) Surface Roughness of Polyamide Film (Number of Protrusions and Size of Protrusions) Surfcom 55, a surface roughness profile measuring instrument manufactured by Tokyo Seimitsu Co., Ltd.
Using 0A type, tip radius of stylus: 5 μm, load: 40
0 mg, measurement length: 1 mm, measurement speed: 0.06 mm /
The surface roughness of the polyamide film sample was measured at sec and a cutoff value of 0.05 mm to obtain a surface roughness curve. The number of protrusions is a predetermined height parallel to the center line of the surface roughness curve (0.02 μm and 0.06 μm from the center line)
After crossing the line + on the + side and then crossing on the negative side, the total number of counts per 1 mm measured in an arbitrary direction was determined by the method of counting 1 when crossing the line on the negative side. The measurement was performed 20 times, and the average value was defined as the “number of protrusions”. In the measurement of the number of protrusions, the maximum value and the minimum value of the horizontal distance between the concave portions (minimum points) before and after the protrusion were determined for the protrusions having a height of 0.06 μm or more from the center line of the obtained surface roughness curve. After measurement, these values were defined as “projection size”. The polyamide film sample was placed in an atmosphere at 23 ° C. and a relative humidity of 55% for at least 24 hours to adjust the condition, and then subjected to the surface roughness measurement.

(3) Transparency (Haze) of Polyamide Film Using a color computer SM-3 manufactured by Suga Test Instruments Co., Ltd., the haze was measured according to ASTM D-1003.
Was measured.

(4) Surface Gloss (Gloss) of Polyamide Film Using a digital variable-angle gloss meter manufactured by Suga Test Instruments Co., Ltd., AST
Gloss was measured according to MD-523.

(5) Sliding property (sliding friction) of polyamide film Static friction of film / mate material film or film / mate material ferrite plate at 23 ° C., 60% RH and 23 ° C., 80% RH according to JIS K7125. The coefficients were measured respectively. However, in order to determine the change in the coefficient of static friction due to the measurement atmosphere (humidity), the measurement was performed by placing the sample portion in a thermo-hygrostat. The measurement was performed five times, and the average value was obtained.

Example 1 A pressure-resistant reaction vessel with an internal volume of 70 liters equipped with a stirrer was charged with 10
20 g of gel-type silica surface-treated with 1 kg of ε-caprolactam, 1 kg of water, and 1 g of γ-aminopropyltriethoxysilane (Mizukasil P707, manufactured by Mizusawa Chemical Industry Co., Ltd., average particle size: 2. 2 μm, γ
-Aminopropyltriethoxysilane added amount: 5% by weight based on the gel type silica), heated to 100 ° C., and stirred at this temperature so that the inside of the reaction system became uniform. Subsequently, the temperature is further raised to 260 ° C.
The mixture was stirred under a pressure of 15 kg / cm ² G for 1 hour. Thereafter, the polymerization reaction was carried out at 260 ° C. for 2 hours under normal pressure while releasing the pressure to evaporate the water from the reaction vessel.
The polymerization reaction was carried out at a temperature of 260 ° C. for 1 hour under a reduced pressure of mHg. After completion of the reaction, the reaction product taken out in a strand form from the lower nozzle of the reaction vessel was introduced into a water bath, cooled, and cut to obtain a polyamide resin pellet in which the gel type silica was uniformly dispersed. Thus, the pellets were immersed in hot water to extract and remove about 10% of unreacted monomers, and then dried under reduced pressure. The relative viscosity of the obtained polymer (polyamide resin) was 3.6.

Next, using a cylindrical mixer, the nylon 6 pellets were dry-blended with 300 ppm by weight of calcium stearate, followed by an extruder (Model: PLABOR-, manufactured by Plastics Engineering Laboratory Co., Ltd.).
GT-40), melt-kneaded at 260 ° C, and extruded from a T-die connected to the extruder. Further, the extruded molten resin was cast into a cooling roll controlled at about 30 ° C. through water to form an unstretched film having a thickness of 120 μm. Thereafter, the film was subjected to a tenter-type biaxial stretching machine (manufactured by Iwamoto Seisakusho Co., Ltd., model: BIX-70).
Using 3), at the stretching temperature of 50 ° C., the stretching ratio is set to 2.6 times in both the longitudinal and transverse directions, and the film is simultaneously biaxially stretched. A stretched film was obtained. The transparency (haze), surface gloss (gloss), number of protrusions, protrusion size and coefficient of static friction (film / mate material film and film / mate material ferrite plate) of the obtained polyamide film are as shown in Table 1. Was.

Example 2 Gel type silica (Mizukasil P707, manufactured by Mizusawa Chemical Industry Co., Ltd., average particle size: 2.2 μm, added amount of γ-aminopropyltriethoxysilane: 5 to gel type silica) (Wt.%) Was not added, but the polymerization reaction, hot water extraction and drying under reduced pressure were carried out in the same manner as in Example 1 to obtain polyamide resin pellets. Therefore, after the pellets were pulverized to a powder state, 95 parts by weight of the pellets and spherical silica surface-treated with γ-aminopropyltriethoxysilane (Mizpearl M201SC5, manufactured by Mizusawa Chemical Industry Co., Ltd., average particle size) And 5 parts by weight of gamma-aminopropyltriethoxysilane (5% by weight based on spherical silica) using a Henschel mixer. Extruded into strands at 260 ° C. using Model PCM30), cooled in a water bath, cut, and dried under reduced pressure to obtain polyamide containing spherical silica in high concentration. A resin pellet was obtained.

Next, using a cylindrical mixer, 46.2 parts by weight of the polyamide resin containing spherical silica at a high concentration and stirrer were added to 96.2 parts by weight of the polyamide resin containing no roughening substance. After dry blending 0.03 parts by weight of calcium phosphate, exactly as in Example 1,
The formation of the unstretched film, followed by sequential biaxial stretching and heat setting was performed to obtain a biaxially stretched film having a thickness of about 17 μm. The transparency, surface glossiness, number of protrusions, and coefficient of static friction (film / mate material film and film / mate material ferrite plate) of the obtained polyamide film were as shown in Table 1.

Example 3 Spherical silica surface-treated with γ-aminopropyltriethoxysilane as a roughening substance (Mizusawa Chemical Industries, Ltd.)
Product name: Mizupearl M201SC5, average particle size:
2.1 μm, the added amount of γ-aminopropyltriethoxysilane: 5% by weight based on spherical silica)
Gel type silica surface-treated with aminopropyltriethoxysilane (Mizukasil P707, manufactured by Mizusawa Chemical Industry Co., Ltd., average particle size: 2.2 μm, added amount of γ-aminopropyltriethoxysilane: gel type silica 5 wt%), and the amount of the polyamide resin not containing the surface roughening substance was changed to 96.2 parts by weight to 9
4.3 parts by weight and a high concentration obtained by treating in the same manner as in Example 2 by using the above gel type silica instead of 4 parts by weight of the polyamide resin containing spherical silica at a high concentration. Except that 6 parts by weight of a polyamide resin containing gel-type silica was used, the same operation as in Example 2 was performed. The transparency, surface glossiness, number of protrusions and coefficient of static friction of the obtained polyamide film (film /
Table 1 shows the measurement results of the mating material film and the film / mating material ferrite plate).

Example 4 The amount of the polyamide resin containing no surface roughening substance was set to 94.
90.5 parts by weight instead of 3 parts by weight, and
Except that the amount of the polyamide resin containing gel type silica in a high concentration was changed to 6 parts by weight to 10 parts by weight, the same operation as in Example 3 was performed. Table 1 shows the measurement results of the transparency, surface gloss, number of protrusions, protrusion size, and coefficient of static friction (film / mate material film and film / mate material ferrite plate) of the obtained polyamide film.

Example 5 Spherical silica surface-treated with γ-aminopropyltriethoxysilane as a roughening substance (Mizusawa Chemical Industry Co., Ltd.)
Product name: Mizupearl M201SC5, average particle size:
2.1 μm, the amount of γ-aminopropyltriethoxysilane added: 5% by weight based on the spherical silica), kaolin (manufactured by Mizusawa Chemical Industry Co., Ltd., trade name: Insulite MC6, average particle size: 5) .9 μm), the amount of the polyamide resin not containing the surface roughening substance was changed to 96.2 parts by weight to 90.5 parts by weight, and the polyamide resin containing spherical silica at a high concentration. Exactly the same as Example 2 except that the above kaolin was used instead of 4 parts by weight, and 10 parts by weight of a polyamide resin containing kaolin at a high concentration obtained by treating in the same manner as in Example 2. Was performed. The transparency, surface glossiness, number of protrusions and coefficient of static friction of the obtained polyamide film (film /
Table 1 shows the measurement results of the mating material film and the film / mating material ferrite plate).

Comparative Example 1 20 g of a surface treated with 1 g of γ-aminopropyltriethoxysilane was used as a roughening substance to be added during the polymerization reaction.
Gel type silica (manufactured by Mizusawa Chemical Industry Co., Ltd., trade name:
(Mizukasil P707, average particle size: 2.2 μm, addition amount of γ-aminopropyltriethoxysilane: 5% by weight based on gel-type silica), and surface treatment with 0.25 g of γ-aminopropyltriethoxysilane 5 g of gel type silica (Mizukasil P707, manufactured by Mizusawa Chemical Industry Co., Ltd., average particle size: 2.2 μm, addition amount of γ-aminopropyltriethoxysilane: 5% by weight based on gel type silica) Example 1 except that
The same operation as described above was performed. Table 1 shows the measurement results of the transparency, surface gloss, number of protrusions, protrusion size, and coefficient of static friction (film / mate material film and film / mate material ferrite plate) of the obtained polyamide film. The number of projections having a height of 0.02 μm or more from the center line in the surface roughness curve obtained in the surface roughness measurement was 28.7 /
mm, but the number of protrusions at a height of 0.06 μm or more from the center line is 2.7 / mm, and the coefficient of static friction in an 80% RH atmosphere in the case of a film / mate material film;
And 6 in the case of film / counterpart ferrite plate.
In the measurement results of the static friction coefficient under the 0% RH atmosphere and the 80% RH atmosphere, the obtained polyamide film is blocking. Therefore, it is understood that the obtained polyamide film has poor slipperiness under high humidity.

Comparative Example 2 The amount of the polyamide resin containing no surface roughening substance was set to 96.
90.5 parts by weight instead of 2 parts by weight, and
Except that the amount of the polyamide resin containing spherical silica at a high concentration was changed to 4 parts by weight to 10 parts by weight, the same operation as in Example 2 was performed. Table 1 shows the measurement results of the transparency, surface gloss, number of protrusions, protrusion size, and coefficient of static friction (film / mate material film and film / mate material ferrite plate) of the obtained polyamide film. The amount of spherical silica added as a roughening substance as a value relative to the amount (weight) of the polyamide resin used, the coefficient of static friction in an 80% RH atmosphere for a film / mate film, and 8 for a film / mate material ferrite plate.
In Example 2, the static friction coefficient in a 0% RH atmosphere was 2000 ppm, 0.53 and 0.23, respectively.
5 in this comparative example, respectively.
0 ppm, 0.51 and 0.24. Therefore, in this comparative example, a large amount of spherical silica as a surface roughening substance was added as compared with the case of Example 2, so that the static friction coefficient under high humidity was higher in the case of the film / mate material and in the case of the film / mate material. In any case of the material ferrite plate, the size is small, and it can be said that the slipperiness is improved. However, the haze and the gloss of the polyamide film obtained in this comparative example were each 1
It is 4.2% and 99, indicating that optical properties such as transparency and surface glossiness are greatly reduced.

Comparative Example 3 Spherical silica surface-treated with γ-aminopropyltriethoxysilane as a roughening substance (Mizusawa Chemical Industry Co., Ltd.)
Product name: Mizupearl M201SC5, average particle size:
2.1 μm, the added amount of γ-aminopropyltriethoxysilane: 5% by weight based on spherical silica)
Precipitated silica surface-treated with aminopropyltriethoxysilane (Mizukasyl P527, manufactured by Mizusawa Chemical Industry Co., Ltd., average particle size: 1.8 μm, added amount of γ-aminopropyltriethoxysilane: precipitated silica) 5 wt%), and the amount of the polyamide resin not containing the surface roughening substance was changed to 96.2 parts by weight to 9
0.5 parts by weight and a high concentration obtained by treating in the same manner as in Example 2 by using the above-mentioned precipitated silica in place of 4 parts by weight of the polyamide resin containing spherical silica in a high concentration. Except that 10 parts by weight of a polyamide resin containing precipitated silica was used. The transparency, surface glossiness, number of protrusions and coefficient of static friction of the obtained polyamide film (film /
Table 1 shows the measurement results of the mating material film and the film / mating material ferrite plate). The number of protrusions at a height of 0.02 μm or more from the center line in the surface roughness curve obtained in the surface roughness measurement is 28.8 / mm, but the number of protrusions at a height of 0.06 μm or more from the center line is Is 0.2 pieces / mm
And 80% R in the case of film / counterpart film
Coefficient of static friction under H atmosphere and film /
In the measurement results of the coefficient of static friction under the 60% RH atmosphere and the 80% RH atmosphere in the case of the mating material ferrite plate, the obtained polyamide film is blocking. Therefore, it is understood that the obtained polyamide film has poor slipperiness under high humidity.

Comparative Example 4 The amount of the polyamide resin containing no surface roughening substance was 90.
96.2 parts by weight instead of 5 parts by weight, and
Except that the amount of the polyamide resin containing kaolin at a high concentration was changed to 10 parts by weight to 4 parts by weight, the same operation as in Example 5 was performed. Table 1 shows the measurement results of the transparency, surface gloss, number of protrusions, protrusion size, and coefficient of static friction (film / mate material film and film / mate material ferrite plate) of the obtained polyamide film.
The number of projections at a height of 0.02 μm or more from the center line in the surface roughness curve obtained in the surface roughness measurement is 15.3 / mm, but the number of projections at a height of 0.06 μm or more from the center line is provided. Is 4.5 pieces / mm. In the measurement results of the static friction coefficient in an 80% RH atmosphere in the case of the film / mate material film and the case of the film / mate material ferrite plate, the obtained polyamide film causes blocking. I have. Therefore, it is understood that the obtained polyamide film has poor slipperiness under high humidity.

Comparative Example 5 Spherical silica surface-treated with γ-aminopropyltriethoxysilane as a roughening substance (Mizusawa Chemical Industry Co., Ltd.)
Product name: Mizupearl M201SC5, average particle size:
2.1 μm, Classification talc (manufactured by Nippon Talc Co., Ltd., trade name: Microace L) in place of the addition amount of γ-aminopropyltriethoxysilane: 5% by weight based on spherical silica
1, average particle size: 1.8 μm), and
In place of 4 parts by weight of the polyamide resin containing spherical silica at a high concentration, the above-mentioned classified talc was used, and 4 parts by weight of a polyamide resin containing a high concentration of classified talc obtained by the same treatment as in Example 2 was used. Except for using, the same operation as in Example 2 was performed. Table 1 shows the measurement results of the transparency, surface gloss, number of protrusions, protrusion size, and coefficient of static friction (film / mate material film and film / mate material ferrite plate) of the obtained polyamide film. The number of protrusions having a height of 0.02 μm or more from the center line in the surface roughness curve obtained in the surface roughness measurement is 21.7 / mm.
However, the number of protrusions at a height of 0.06 μm or more from the center line is 4.7 / mm, which is 80% RH atmosphere in the case of the film / mate material film and the case of the film / mate material ferrite plate. In the measurement result of the coefficient of static friction, the obtained polyamide film is blocking. Therefore, it is understood that the obtained polyamide film has poor slipperiness under high humidity.

[0056]

[Table 1]

Example 6 The same operation as in Example 2 was carried out except that the stretching ratio was changed to 2.6 times in both the vertical and horizontal directions and set to 2.0 times.
Table 2 shows the measurement results of the number of protrusions and the coefficient of static friction (film / mate material film) of the obtained polyamide film.

Example 7 The same operation as in Example 2 was carried out except that the stretching ratio was changed to 2.6 times in both the vertical and horizontal directions and set to 3.0 times.
Table 2 shows the measurement results of the number of protrusions and the coefficient of static friction (film / mate material film) of the obtained polyamide film.

Comparative Example 6 Except that the stretching ratio was changed to 2.6 times in both the longitudinal and transverse directions and set to 1.0 times, that is, only heat fixing at 190 ° C. for 1 minute was performed without stretching. The same operation as in Example 2 was performed. Table 2 shows the measurement results of the number of protrusions and the coefficient of static friction (film / mate material film) of the obtained polyamide film. The number of protrusions having a height of 0.06 μm or more from the center line in the surface roughness curve obtained in the surface roughness measurement was 3.4 / mm, and the number of protrusions was 60% RH in the case of the film / counterpart film, and 80% R
In the measurement result of the coefficient of static friction in the H atmosphere, the obtained polyamide film is blocking. Therefore, it is understood that the obtained polyamide film has poor slipperiness under high humidity.

Comparative Example 7 The same operation as in Example 2 was carried out except that the stretching ratio was changed to 2.6 times in both the vertical and horizontal directions and set to 1.5 times.
Table 2 shows the measurement results of the number of protrusions and the coefficient of static friction (film / mate material film) of the obtained polyamide film. The number of protrusions having a height of 0.06 μm or more from the center line in the surface roughness curve obtained in the surface roughness measurement is 3.8.
The obtained polyamide film is blocking in the measurement result of the coefficient of static friction in an 80% RH atmosphere in the case of the film / countermaterial film. Therefore, it is understood that the obtained polyamide film has poor slipperiness under high humidity.

[0061]

[Table 2]

[0062]

As is clear from the examples and comparative examples described above, according to the present invention, the surface roughness measured by the stylus type two-dimensional surface roughness measuring device having a stylus radius of 5 μm is measured from the center line. The number of protrusions of 0.06 μm or more is 6 to 30 /
The projections are formed on the surface at a density such as mm, so that in the polyamide film having excellent pinhole resistance and oxygen gas barrier properties, its optical properties such as transparency and surface gloss were maintained. On, slippery,
In particular, excellent sliding properties can be obtained under high humidity. Therefore, the polyamide film of the present invention has high utility as a technique for manufacturing a moisture-rich nylon film for food packaging, which is often used particularly in a high humidity environment.

Claims (4)

[Claims] 1. In a surface roughness measurement, a distance of 0.0 from a center line.
It has a surface roughness in which the number of protrusions having a height of 6 μm or more is 6 to 30 / mm, and has a haze of 10% or less and a gross value of more than 110. Excellent polyamide film. 2. The polyamide film according to claim 1, which is obtained by stretching a raw polyamide film obtained by molding a composition obtained by blending a roughening substance with a polyamide resin in an area ratio of three times or more. 3. The surface roughening substance is inorganic fine particles.
The polyamide film according to 1. 4. The polyamide film according to claim 2, wherein 50% by weight or more of the polyamide resin is poly-ε-capramide or a copolymer mainly composed of a repeating structural unit of poly-ε-capramide.