JPWO2010113742A1 - Polypropylene resin film for surface protection and surface protection film - Google Patents

Abstract

[PROBLEMS] To provide excellent heat-resistant dimensional stability and flatness, excellent impact resistance and bonding processability, less fish eyes, and no wrinkles or tarmi when wound on a roll. And a protective film obtained by providing an adhesive layer on the surface-protective polypropylene resin film and the surface-protective polypropylene resin film. SOLUTION: A polypropylene resin film substantially comprising a polypropylene resin as a main component, wherein the 20 ° C. xylene soluble part content is more than 9% and less than 15%, and the content of the crystal nucleating agent is 100 ppm or less. Surface thickness, wherein the thickness variation rate in the width direction of the film is 1% or more and 10% or less, the dynamic friction coefficient is 1.0 or less, and the tensile elastic modulus is 500 MPa or more and 900 MPa or less Polypropylene resin film. [Selection figure] None

Description

  The present invention relates to a surface-protective polypropylene-based resin film and a surface protective film, and in particular, has high thermal deformation resistance and flatness at high temperatures, and is excellent in processing suitability such as adhesive processing, and an additive. The present invention relates to a surface-protective polypropylene-based resin film that is suitable for the surface protection of various articles, and a surface-protective film using the surface-protective polypropylene-based resin film. is there.

  Polypropylene-based unstretched films have good transparency and are inexpensive, and are therefore widely used as base materials for surface protection films for the purpose of protecting the surface of various packaging materials such as food packaging and various articles.

  Furthermore, it is used as a surface protection film for protecting electronic precision products such as metal plates, decorative plates, resin plates, glass plates, related materials such as liquid crystal panels and polarizing plates, parts and related members, and automobile coatings. Or a surface protection film for protecting a resist film or an etching resistance film for partially plating a connection terminal portion of a flexible printed circuit board, a semiconductor by laminating a film on a surface without a circuit of a semiconductor element It is used as a surface protective film for protecting the surface of the element.

In recent years, with the expansion of applications, demands for quality and cost reduction have increased, and in addition to the suitability for bonding to protected objects, a film for surface protection excellent in ease of processing adhesives is required. ing.
In particular, the processing temperature is increasing for the purpose of increasing the processing speed of adhesive processing, etc. Even if the adhesive is processed at a high temperature, thermal deformation due to the processing temperature is small and dimensional stability during processing is good. There is a need (sometimes simply referred to as heat-resistant dimensional stability).

  Several polypropylene-based films have been disclosed as techniques for improving the above heat-resistant dimensional stability (see, for example, Patent Documents 1 to 4).

  However, the heat-sealable polypropylene film disclosed in Patent Document 1 has insufficient rigidity, and the transparent polypropylene sheet disclosed in Patent Document 2 is difficult to bond.

Also, the surface protective polypropylene films described in Patent Document 3 and Patent Document 4 have high rigidity and are inferior in bonding process suitability.
Furthermore, there is a problem that wrinkles and tarmi are likely to occur when the film is wound on a roll.
In addition, there is a problem that the film is distorted when an adhesive is applied.

Japanese Patent Laid-Open No. 09-12657 JP 2003-170485 A WO2006 / 057294 JP 2007-270005 A

  The present invention is excellent in heat-resistant dimensional stability and flatness, excellent in impact resistance and laminating workability, has little fish eye, and has no wrinkles or tarmi when wound on a roll. An object of the present invention is to provide a surface-protective polypropylene-based resin film suitable as a film and a protective film in which an adhesive layer is provided on the surface-protective polypropylene-based resin film.

  As a result of intensive studies to solve the above problems, the present inventors have completed the present invention.

  That is, the present invention is a polypropylene resin film substantially comprising a polypropylene resin as a main component, the 20 ° C. xylene soluble part amount is more than 9% and less than 16%, and the content of the crystal nucleating agent is The thickness variation rate in the width direction of the film is 1% or more and 10% or less, the dynamic friction coefficient is 1.0 or less, and the tensile elastic modulus is 500 MPa or more and 900 MPa or less. Polypropylene resin film for surface protection.

  In this case, the content of the antiblocking agent in the film is preferably 50 ppm or less, and the blocking resistance is preferably 10 mN or less.

In this case, the number of fish eyes having a maximum diameter of 0.2 mm or more in the film is 0 / m ² and the number of fish eyes having a maximum diameter of less than 0.2 mm is 100 / m ² or less. preferable.

  Furthermore, in this case, the Young's modulus in the longitudinal direction at 23 ° C. of the film is preferably 500 Mpa or more.

  In this case, the impact strength of the film at 23 ° C. is preferably 0.3 J or more.

  Furthermore, in this case, it is preferable that it comprises at least an acrylate-based antioxidant and at least one antioxidant selected from a phosphorus-based antioxidant and a phenol-based antioxidant. .

  Furthermore, in this case, it is preferable that the fluctuation range of the 20 ° C. xylene soluble part amount of the film is less than 2%.

  Furthermore, the present invention is a surface protective film in which an adhesive layer is provided on at least one surface of the above-mentioned surface protective polypropylene resin film.

The present invention is excellent in heat-resistant dimensional stability and flatness, excellent in impact resistance, bonding processability and whitening prevention effect, has little fish eye, and is free from wrinkles and tarmi when wound on a roll. It is suitable as a base film for the film.
Since the polypropylene resin film for surface protection of the present invention is excellent in heat-resistant dimensional stability, for example, it is suitable for secondary processing such as adhesive processing, and is particularly subjected to treatment such as drying at a high temperature around 130 ° C. In addition, since the occurrence of hot stagnation and film sagging is suppressed, the productivity of the secondary processing can be improved, and the generation of defective products due to hot sag and film sagging can be suppressed.
Moreover, it is preferable that the polypropylene resin film of the present invention does not substantially contain an antiblocking agent. For example, when a film containing an antiblocking agent is run, the antiblocking agent falls off due to wear or the like. Therefore, the contamination and the occurrence of troubles due to the fallout are suppressed.
In addition, although the present invention does not substantially contain a lubricant or an anti-blocking agent, the surface roughness is appropriate, the slipperiness and blocking resistance of the film are good, and the film is excellent in rigidity. Is easy to handle.
Moreover, since it is excellent in transparency, it is excellent in the visibility of a to-be-protected body. Moreover, since there is the intensity | strength of a film, it is excellent in handleability.
In addition, despite its improved heat-resistant dimensional stability, it has excellent impact strength and maintains good impact resistance by being made of block polypropylene resin. High reliability when there is.

The polypropylene-based resin film of the present invention contains a polypropylene-based resin as a main component. Preferably, the film preferably contains 70% by weight or more of polypropylene-based resin, and more preferably 80% by weight or more.
The polypropylene resin used in the present invention can be used by mixing one or three of homopolypropylene resin, random copolymerized polypropylene resin copolymerized with ethylene and other α-olefins, and block copolymerized polypropylene resin. .
From the viewpoint of transparency, it is preferable to mainly use a homopolypropylene resin or a random copolymerized polypropylene resin copolymerized with ethylene or other α-olefin, in order to improve impact resistance and slipperiness, particularly blocking resistance. It is preferable to mainly use a block copolymerized polypropylene resin. The mixing ratio can be adjusted arbitrarily.

Although it does not specifically limit regarding the composition of said polypropylene resin, If it is a random copolymerization polypropylene resin, it is preferable that alpha-olefin content is 5% or less from the surface of heat-resistant dimensional stability. In addition, in the case of a block copolymerized polypropylene resin, a 20 ° C. xylene-soluble part amount is preferably 3 to 50% from the viewpoint of heat-resistant dimensional stability, slipperiness, and blocking resistance, and more preferably in the range of 5 to 30%. preferable.
The intrinsic viscosity of the whole polypropylene resin is 1.5 to 4.0, the intrinsic viscosity of the 20 ° C. xylene soluble part is 1.0 to 4.0, and the intrinsic viscosity of the 20 ° C. xylene insoluble part is 1.0 to 4. Those that are zero are preferred. The melt flow rate of the polypropylene resin used in the present invention is preferably 2 to 20 g / 10 min at 230 ° C.

As the α-olefin random copolymer elastomer used in the present invention, ethylene-propylene, ethylene-butene, a propylene-butene binary system, an ethylene-propylene-butene ternary copolymer or a mixture thereof is used. Can be used. Moreover, you may use the copolymer which copolymerized another monomer in the range which does not impair the characteristic. In particular, the use of the above binary copolymer is preferable. In addition, it is preferable to use a laminate having a bigat softening point of 60 ° C. or lower and a surface hardness of 80 ° or lower from the viewpoint that a preferable elastic force can be imparted to the laminate.
In the present invention, it is particularly preferable to contain a block copolymerized polypropylene resin in terms of heat resistance and slipperiness.

  Further, other small amounts of α-olefin random copolymer elastomer, ionomer, and other master batches may be added for various purposes.

The polypropylene resin film of the present invention needs to have a 20 ° C. xylene soluble part amount of more than 9% and less than 16%.
If it is 9% or less, the film is likely to be plastically deformed during high-temperature processing, and the film is inferior in bonding suitability and whitening prevention effect.
If it is 16% or more, the film tends to be stretched and the adhesive coating processability is poor, such being undesirable.
The lower limit of the 20 ° C. xylene soluble part is more preferably 10% or more from the viewpoint of preventing whitening when the film is bent, and more preferably 14% or less from the viewpoint of the anti-blocking property of the film.

In the present invention, as described above, it is preferable not to add a lubricant or an anti-blocking agent that is carried out in a normal polypropylene resin film, but in that case, it is necessary to suppress deterioration of the slipperiness and blocking property of the film. is there. The correspondence is preferably carried out by the above-described resin composition, in particular, film surface protrusions with a sea / island structure made of a block copolymer resin or an ethylene copolymer elastomer.
At this time, as a slip characteristic of the film of the present invention, it is necessary that the coefficient of dynamic friction is 1.0 or less in the evaluation described later. Further, it is more preferably 0.9 or less, and most preferably 0.8 or less.
When the coefficient of dynamic friction is outside this range, when the film is wound on a roll, when the air between the films escapes, sticking between the films is likely to occur, which is one factor that causes wrinkles and sagging.
Moreover, as an anti-blocking characteristic of the film of this invention, it is preferable that it is 1-10 mN or less by evaluation mentioned later. More preferably, it is 1-7 mN or less.
On the other hand, the formation of film surface protrusions due to the sea / island structure with the block copolymer resin causes a decrease in transparency of the film. Therefore, in this method, the effect of improving slipperiness and blocking resistance due to the formation of surface protrusions and transparency Ensuring sex is a contradictory phenomenon. Therefore, the haze value of the film is an important factor.
Therefore, in the present invention, it is important to set the haze value of the film to 40% or less. 35% or less is preferable and 30% or less is more preferable. By setting the haze value to 40% or less, the visibility of the article to be packaged or the object to be protected is improved, and when used as a packaging bag material, the contents of the article to be packaged can be easily confirmed. Further, when used as a material for a surface protective film, for example, it is possible to inspect an object to be protected while the surface protective film is adhered. On the other hand, when the haze value exceeds 40%, the transparency is deteriorated and the visibility of the article to be packaged or the object to be protected is lowered, which is not preferable. On the other hand, the lower limit of the haze value is preferable because the transparency is improved. However, 5% or more is preferable and 10% or more is more preferable in terms of imparting slipperiness by the above method.

  Moreover, it is preferable that the content of antiblocking agents, such as inorganic and / or organic microparticles | fine-particles, in the film for surface protection polypropylene resin films of this invention is 50 ppm or less. The content of the anti-blocking agent is more preferably 10 ppm or less, and particularly preferably the detection limit or less by a usual quantitative method such as ash or elemental analysis. That is, it is preferable not to contain an antiblocking agent substantially. Here, substantially not containing an antiblocking agent has the same meaning as in the case of the above-mentioned lubricant. By this measure, the anti-blocking agent is prevented from falling off due to film abrasion in the film production and secondary processing steps, so that contamination, troubles, and the like due to the fall-off are suppressed.

  It is important that the polypropylene resin film for surface protection of the present invention has a content of a lubricant such as polyethylene wax, calcium stearate, erucamide, ethylenebiserucamide in the film of 50 ppm or less. The content of the lubricant is more preferably 10 ppm or less, and particularly preferably the detection limit or less by a usual quantitative method such as elemental analysis or extraction method. That is, it is preferable that substantially no lubricant is contained. Here, “substantially containing no lubricant” means forming a film without positively adding the lubricant. The above range is to include that there is a case where a minute amount is mixed due to brand switching or the like at the time of manufacturing a raw material polymer or film without positively adding a lubricant, and it is a preferable embodiment that substantially does not contain a lubricant. is there. In this method, the lubricant is added to the surface of the film and the contamination of the protected object due to the subsequent transfer to the protected object is prevented in the method of blending the lubricant and improving the slipperiness of the film. The degree is retained.

In the present invention, the tensile elastic modulus needs to be 500 MPa or more and 900 MPa or less.
If the tensile modulus is too small, the film is deformed when the film is wound on the roll, and as a result, stress remains on the roll, causing wrinkles and talmi. On the other hand, if the tensile modulus is too large, it becomes difficult to bond the film after applying the adhesive.

It is preferable that the polypropylene resin film for surface protection of the present invention has a film crystallinity of 34 to 65% according to a measurement method described later. If the degree of crystallinity is less than 34%, the heat-resistant dimensional stability is difficult to be exhibited, and when processing in a later process is performed, the film is likely to be damaged or stretched, resulting in poor flatness. On the other hand, when the crystallinity exceeds 65%, the transparency of the film is remarkably deteriorated. On the other hand, when the degree of crystallinity exceeds 65%, the Young's modulus increases and the bonding processability deteriorates.
The lower limit of the crystallinity of the film is more preferably 40% or more, and most preferably 50% or more from the viewpoint of heat-resistant dimensional stability. On the other hand, the upper limit of the crystallinity of the film is preferably 60% or less from the viewpoint of transparency.

  Moreover, the polypropylene resin film for surface protection of the present invention may be a polypropylene resin film that has reached a desired crystallinity (34 to 65%) by a production method even if it does not substantially contain a crystal nucleating agent. Good. The manufacturing method may be achieved by raising the temperature of the cooling roll when the molten resin is taken and cooled and solidified, or by heat treatment (annealing).

  The polypropylene resin film for surface protection of the present invention can be added if the crystal nucleating agent is in the range of 100 ppm or less. By adding a crystal nucleating agent, the heat-resistant dimensional stability of the film can be improved. On the other hand, if the crystal nucleating agent is added in excess of 100 ppm, depending on the melt extrusion conditions of the resin, fish eyes in the film tend to increase, which causes a problem. Further, it is not preferable because a problem such as a reduction in productivity such as pressure increase due to clogging of a filter provided in an extruder for the purpose of removing foreign substances in the resin occurs.

  Examples of the crystal nucleating agent include, but are not limited to, a crystal nucleating agent mainly composed of a metal salt of rosin, a sorbitol-based crystal nucleating agent, and a crystal nucleating agent composed of an aromatic organophosphate metal salt.

The polypropylene resin film for surface protection of the present invention preferably has a birefringence (Δn) of 0.4 × 10 ^{−3 to} 2.5 × 10 ⁻³ . When the birefringence exceeds 2.5 × 10 ⁻³ , the anisotropy becomes excessively large and tends to cause wrinkles and tarmi.
On the other hand, if the birefringence is less than 0.4 × 10 ⁻³ , the film is likely to be stretched, resulting in poor flatness and poor heat-resistant dimensional stability. From the viewpoint of maintaining heat-resistant dimensional stability and flatness, the birefringence of the film is preferably 0.6 × 10 ⁻³ or more, and more preferably 0.8 × 10 ⁻³ or more. On the other hand, from the viewpoint of preventing wrinkles and talmi of the film, the birefringence of the film is preferably 2.3 × 10 ⁻³ or less, and more preferably 2.2 × 10 ⁻³ or less.

  In the present invention, the polypropylene resin film for surface protection of the present invention preferably has an impact strength at 23 ° C. of 0.3 J or more. 0.5J or more is more preferable. In general, when the rigidity and heat-resistant dimensional stability described above are improved, the impact strength moves in a decreasing direction. When the impact strength is reduced, the reliability of the impact resistance during use when used as a packaging bag, a protective film or the like is lowered. Therefore, it is preferable to satisfy the above-mentioned characteristics while giving the above-mentioned characteristics. The upper limit is preferably about 0.8 J from the balance with other characteristics.

The method for imparting the impact strength is not limited, but is greatly affected by the above-described ethylene content. It is preferably achieved as the overall effect of the preferred embodiments described herein including the ethylene content.

In the present invention, the polypropylene resin film for surface protection of the present invention preferably has 0 fisheye / m ² having a maximum diameter of 0.2 mm or more in the film. Further, the number of fish eyes having a maximum diameter of less than 0.2 mm is preferably 100 / m ² or less. The number of fish eyes having a maximum diameter of less than 0.2 mm is most preferably 0 / m ² or less, but the above range is preferable in view of economic efficiency and market demand. 2-80 pieces / m ² or less is more preferable, and 2-60 pieces / m ² or less is more preferable. In addition, the minimum diameter of the fish eye that can be visually determined is said to be 0.03 to 0.05 mm. By this correspondence, when it is used as a base film of a protective film, for example, when it is used as a base film of a protective film, it is possible to suppress the occurrence of troubles due to the penetration of the plating solution into the protective part due to the above-mentioned poor adhesion.

The means for achieving the above characteristics is not limited, but the antioxidant may be optimally blended as described later.
The acrylate antioxidant of the present invention is an antioxidant having a phenol derivative containing an acrylate residue in the molecule. Examples of the acrylate compound include 2,4-di-t-amyl-6- [1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl] phenyl acrylate, 2,4-di-t. -Amyl-6- [1- (3,5-di-t-amyl-2-hydroxyphenyl) butyl] phenyl acrylate, 2,4-di-t-amyl-6- [1- (3,5-di -T-amyl-2-hydroxyphenyl) propyl] phenyl acrylate, 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, and the like.

  Preferably, 2,4-di-t-amyl-6- [1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl] phenyl acrylate and 2-t-butyl-6- (3- t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate.

  As said acrylate compound, it can select from a commercially available thing suitably and can be used. For example, Sumitizer GM (registered trademark) manufactured by Sumitomo Chemical Co., Ltd., which is 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2,4 -Sumitizer GS (registered trademark) manufactured by Sumitomo Chemical Co., Ltd., which is di-t-amyl-6- [1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl] phenyl acrylate Can do. In particular, it is preferable to use a Sumilizer GS (registered trademark).

Although the compounding quantity of the said acrylate antioxidant in this invention is not limited, The range of 100-1000 ppm is preferable with respect to the above-mentioned all polypropylene resin composition. 200 to 800 ppm is more preferable, and 300 to 700 ppm is more preferable. When it exceeds 1000 ppm, the contamination of the cooling roll increases in the film forming step, which is not preferable. The film is also unfavorable because it dyes a pale yellow color unique to antioxidants. On the contrary, if it is less than 100 ppm, the combined effect described later is decreased, which is not preferable. It is preferable to lower the upper limit of the blending amount of the acrylate antioxidant alone than the above two kinds of antioxidants. The acrylate antioxidant is a polypropylene resin rubber compared to other antioxidants. Due to the high solubility in the component, it is more distributed to the rubber component in the film, and the rubber component portion has a slower crystallization rate by the cooling roll than the base resin, so that the rubber is in contact with the cooling roll. It is surmised that the above-mentioned acrylate-based antioxidant distributed to the components easily migrates to the cooling roll, and thus is caused by increasing the contamination degree of the cooling roll.
For example, this is a unique phenomenon that occurs in the present invention that does not occur in the film formation using the homopolypropylene resin disclosed in Patent Document 23 and the like described above.

  Specific examples of the phosphorus antioxidant include a heat stabilizer containing a trivalent phosphorus atom in the molecule, and the phosphorus atom has at least one P—O—C bond. For example, tributyl phosphite, trioctyl phosphite, trilauryl phosphite, tristearyl phosphite, tridecyl phosphite, tricresyl phosphite, tricyclohexyl phosphite, triphenyl phosphite, trilauryl thiophosphite, tris ( 2-ethylhexyl) phosphite, tris (isodecyl) phosphite, tris (tridecyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, tris (butoxyethyl) phosphite, tris (nonylphenyl) Phosphite, tris (3,5-di-t-butyl-4-hydroxyphenyl) phosphite, tris [4,4′-isopropylidenebis (2-t-butylphenol)] phosphite, tris (1,3- Gieste (Royloxyisopropyl) phosphite, 2-ethylhexyl diphenyl phosphite, decyl diphenyl phosphite, phenyl di-2-ethylhexyl phosphite, phenyl didecyl phosphite, phenyl diisodecyl phosphite, phenyl di (tridecyl) phosphite, diphenyl nonyl phosphite, Diphenyl isooctyl phosphite, diphenyl isodecyl phosphite, diphenyl mono (tridecyl) phosphite, dibutyl hydrogen phosphite, 4,4′-isopropylidene diphenol alkyl (C12 to C15) phosphite, 4,4′-butylidenebis ( 3-methyl-6-tert-butylphenyl) di-tridecyl phosphite, 2,2-methylenebis (4,6-di-tert-butylphenyl) octyl Sufite, 2,2'-ethylidenebis (4,6-di-t-butylphenol) fluorophosphite, bis (2,4-di-t-butyl-6-methylphenyl) .ethyl phosphite, 4,4 ' -Isopropylidenebis (2-t-butylphenol) di (nonylphenyl) phosphite, distearyl pentaerythritol diphosphite, di (nonylphenyl) pentaerythritol diphosphite, diphenylpentaerythritol diphosphite, phenyl 4, 4'-isopropylidenediphenol pentaerythritol diphosphite, bis (4,6-di-t-butylphenyl) pentaerythritol diphosphite, bis (2,6-di-t-butyl-4-methylphenyl) Pentaerythritol diphosphite, phenyl -Bisphenol A pentaerythritol diphosphite, tetraphenyldipropylene glycol diphosphite, tetra (tridecyl) -1,1,3-tris (2-methyl-5-tert-butyl-4-hydroxyphenyl) butanediphos Phyto, tetra (C12-C15 mixed alkyl) -4,4′-isopropylidene diphenyl diphosphite, tetra (tridecyl) -4,4′-butylidenebis (3-methyl-6-tert-butylphenol) diphosphite, tetrakis (4 , 6-Di-t-butylphenyl) -4,4′-biphenylene diphosphonite, tetrakis (2-methyl-4,6-di-t-butylphenyl) -4,4′-biphenylene diphosphonite Bis (octylphenyl) -bis [4,4′-butylidenebis (3-methyl) 6-t-butylphenol)] • 1,6-hexanediol diphosphite, hydrogenated-4,4′-isopropylidene diphenol polyphosphite, 9,10-di-hydro-9-oxa-9-oxa- 10-phosphaphenanthrene-10-oxide, 2-[{2,4,8,10-tetrakis (1,1-dimethylethyl) dibenzo (D, F) (1,3,2) -dioxaphos Fephin-6-yl} oxy] -N, N-bis [2-[{2,4,8,10-tetrakis (1,1-dimethylethyl) dibenzo (D, F) (1,3,2) -Dioxaphosphine-6-yl} oxy] ethyl] ethanamine, 1,1,3-tris (2-methyl-4-di-tridecylphosphite-5-t-butylphenyl) butane, 3,4 , 5,6-Tetraben Like 1,2-oxa phosphane-2-oxide.

Preferably, those having no pentaerythritol skeleton, tris (2,4-di-t-butylphenyl) phosphite, tris (3,5-di-t-butyl-4-hydroxyphenyl) phosphite, Bis (2,4-di-t-butyl-6-methylphenyl) .ethyl phosphite, tetrakis (2-methyl-4,6-di-t-butylphenyl) -4,4'-biphenylenediphosphonite It is.

  Commercially available products can also be used as the phosphorus-based antioxidant used in the present invention. For example, Irgafos 168 (manufactured by Ciba Specialty Chemicals), Irgafos 38 (manufactured by Ciba Specialty Chemicals), GSY- P101 (manufactured by Yoshitomi Fine Chemicals), Ultranox 641 (manufactured by GE Specialty Chemicals), and the like.

  Although the compounding quantity of the said phosphorus antioxidant in this invention is not limited, The range of 500-5000 ppm is preferable with respect to the above-mentioned all polypropylene resin composition. 1000 to 4000 ppm is more preferable, and 1500 to 3000 ppm is more preferable. If it is less than 500 ppm, the effect of using an antioxidant described later decreases, which is not preferable. On the other hand, if it exceeds 5000 ppm, the effect of using an antioxidant described later is saturated, causing film whitening due to the migration of the antioxidant to the film surface, contamination of the cooling roll in the film forming process, and the like. It is not preferable.

The phenolic antioxidant used in the present invention is an antioxidant having a phenol derivative in the molecule, such as 2,6-di-t-butyl-4-methylphenol, 2,6-di-t. -Butyl-4-ethylphenol, 2,6-dicyclohexyl-4-methylphenol, 2,6-di-t-amyl-4-methylphenol, 2,6-di-t-octyl-4-n-propylphenol 2,6-dicyclohexyl-4-n-octylphenol, 2-isopropyl-4-methyl-6-t-butylphenol, 2-t-butyl-2-ethyl-6-t-octylphenol, 2-isobutyl-4-ethyl -6-t-hexylphenol, 2-cyclohexyl-4-n-butyl-6-isopropylphenol, dl-α-tocopherol, t-butyl Droquinone, 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 4,4'-butylidenebis (3-methyl-6-tert-butylphenol), 4,4'-thiobis (3-methyl-6) -T-butylphenol), 2,2-thiobis (4-methyl-6-t-butylphenol), 4,4'-methylenebis (2,6-di-t-butylphenol), 2,2'-methylenebis [6- (1-methylcyclohexyl) -p-cresol], 2,2′-ethylidenebis (4,6-di-t-butylphenol), 2,2′-butylidenebis (2-t-butyl-4-methylphenol), 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2- [1- (2-hydroxy-3,5-di-t Pentylphenyl) ethyl] -4,6-di-t-pentylphenyl acrylate, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, triethylene glycol-bis [3 -(3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,2-thiodiethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], N, N′-hexamethylenebis (3,5-di-t-butyl-4- Hydroxy-hydrocinnamide), 3,5-di-tert-butyl-4-hydroxybenzylphosphonate-diethyl ester, tris (2,6-dimethyl-3-hydride) Xyl-4-t-butylbenzyl) isocyanurate, tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, tris [(3,5-di-t-butyl-4-hydroxyphenyl) Propionyloxyethyl] isocyanurate, tris (4-t-butyl-2,6-dimethyl-3-hydroxybenzyl) isocyanurate, 2,4-bis (n-octylthio) -6- (4-hydroxy-3,5 -Di-t-butylanilino) -1,3,5-triazine, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, 2,2'-methylenebis (
4-methyl-6-tert-butylphenol) terephthalate, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, 3,9-bis [1,1-dimethyl-2- {β- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy} ethyl] -2,4,8,10-tetraoxaspiro [5,5] Undecane, 2,2-bis [4- (2- (3,5-di-t-butyl-4-hydroxyhydrocinnamoyloxy)) ethoxyphenyl] propane, β- (3,5-di-t-butyl -4-hydroxyphenyl) propionic acid stearyl ester and the like.

  Preferably, β- (3,5-di-t-butyl-4-hydroxyphenyl) propionic acid stearyl ester, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] Methane, tris (3,5-di-t-butyl-4-hydroxybenzyl) isocyanurate, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4- Hydroxybenzyl) benzene, dl-α-tocopherol, tris (2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl) isocyanurate, tris [(3,5-di-tert-butyl-4-hydroxyphenyl) ) Propionyloxyethyl] isocyanurate, 3,9-bis [1,1-dimethyl-2- {β- (3-tert-butyl-4-hydroxy-5-methyl) Butylphenyl) propionyloxy} ethyl] -2,4,8,10-tetra-oxa-spiro [5,5] undecane.

  Commercially available products may be used as the phenolic antioxidant used in the present invention, for example, Irganox 1010 (Ciba Specialty Chemicals), Irganox 1076 (Ciba Specialty Chemicals), Irganox 1330 (manufactured by Ciba Specialty Chemicals), Irganox 3114 (manufactured by Ciba Specialty Chemicals), Irganox 1425WL (manufactured by Ciba Specialty Chemicals) and the like.

  Although the compounding quantity of the said phenolic antioxidant in this invention is not limited, The range of 500-5000 ppm is preferable with respect to the above-mentioned all polypropylene resin composition. 1000 to 4000 ppm is more preferable, and 1500 to 3000 ppm is more preferable. If it is less than 500 ppm, the effect of using an antioxidant described later decreases, which is not preferable. On the other hand, if it exceeds 5000 ppm, the effect of using an antioxidant described later is saturated, causing film whitening due to the migration of the antioxidant to the film surface, contamination of the cooling roll in the film forming process, and the like. It is not preferable.

  In the present invention, as described above, it comprises at least two antioxidants selected from at least one selected from the group consisting of acrylate antioxidants, phosphorus antioxidants and phenolic antioxidants. However, it is a more preferable embodiment that three types of acrylate antioxidant, phosphorus antioxidant and phenolic antioxidant are used in combination.

  The above three kinds of antioxidants are not limited to one type each. Two or more of each type may be used in combination, and in addition to the above three types of antioxidants, for example, an antioxidant having another structure such as a sulfur-based antioxidant may be further used in combination.

  By using a plurality of the above-mentioned antioxidants in combination, a high level of fisheye mixing suppression effect that cannot be obtained by a combination of conventionally known antioxidants is exhibited.

Phenol-based antioxidants and phosphorus-based antioxidants have little selectivity for the antioxidant effect with respect to each component of the raw material resin composition described above, but acrylate-based antioxidants are used with the rubber part of the polypropylene-based block copolymer. It is known that the affinity is strong and the tendency to preferentially suppress the deterioration of the rubber part. On the other hand, regarding the generation of fish eyes, the contribution of the deterioration of the rubber part is large. Therefore, it is presumed that the combined use of the above-mentioned plurality of antioxidants led to a significant reduction in fish eyes.

  Moreover, the polypropylene resin film for surface protection of the present invention preferably has a thickness variation rate in the width direction of the film of 1 to 10%. When the thickness variation rate is less than 1%, there is no problem in terms of quality, but the time required for adjusting the thickness becomes enormous and the economic efficiency is remarkably lowered, which is not realistic. On the other hand, when the thickness variation rate exceeds 10%, the flatness (waving and curling) of the film is deteriorated, and wrinkles and tarmi occur when wound on a roll. The thickness variation rate is more preferably 1.5 to 8%, and most preferably in the range of 2 to 5%.

  The method for preparing the polypropylene resin composition containing the antioxidant used in the present invention is not particularly limited, and examples thereof include known methods. Examples thereof include a method of heat-melt kneading using a kneader such as a kneader, a Banbury mixer, or a roll, and a method of heat-melt kneading using a single screw or twin screw extruder. Various resin pellets may be dry blended. In the method for preparing the composition, the antioxidant may be added directly to the respective powders, or may be added as a master batch mixed in advance with the aforementioned polypropylene resin. When adding as a masterbatch, it may be prepared for each additive or may be prepared by mixing two or more. Moreover, you may implement combining the commercially available resin in which the said additive was mix | blended well. In addition, the composition may be prepared in advance to be supplied to a film forming process and supplied to a film forming extruder, or the components constituting the composition may be supplied to the film forming extruder. It may be supplied and prepared to form a film.

  In addition, the variation range of the 20 ° C. xylene soluble part amount of the film is 2% or less, which is important for preventing the film from being distorted when an adhesive is applied. Preferably it is 1% or less.

  As a method of suppressing the fluctuation rate within the above range, for example, a method in which raw materials are mixed little by little and charged into an extruder each time, a method in which the shape of the hopper is close to a cylindrical shape and segregation is not performed, and a stirring device is provided inside the hopper However, from the viewpoint of production stability and prevention of dust generation, a method of providing a segregation prevention device spacer in the hopper is preferable. In the first place, segregation occurs when a part of the mixed raw material resin is blended with a material that is greatly different in the speed of sliding down the inclined inner wall at the bottom of the hopper, for example, a soft and non-slip raw material such as an elastomer, along the inner wall. This is because the mixing ratio varies between the raw material going down and the raw material going down near the center.

  Therefore, as the method for preventing segregation, as described above, 1) a method in which raw materials are put into an extruder before segregation occurs, that is, a method in which raw materials are mixed little by little and are put into an extruder each time. 2) A method for preventing the difference in the speed of sliding down the inner wall of the hopper between the raw materials, that is, a method for making the shape of the hopper close to a cylindrical shape. 3) A mixing device, for example, a method in which a screw is inserted in the vertical direction and rotated in order to prevent the raw material from segregating even when the raw material is segregated. 4) A method in which all raw materials are dropped along the wall so that the raw materials fall in the hopper without segregation, that is, a method in which a segregation preventing spacer is provided in the hopper. Among these methods, 1) and 2) have a problem in productivity because the amount of the mixed raw material is small, so that when the problem occurs in the mixing apparatus, the raw material can be quickly consumed. The method 3) has a problem that since the raw materials are continuously mixed, the raw materials are shaved and dust is easily generated. Therefore, the method 4) is most useful industrially.

Although the shape of the apparatus for achieving the segregation preventing method of the above 4) is specifically shown below, it can be carried out with appropriate modifications within a range that can be adapted to the gist of the present invention. Both are included in the technical scope of the present invention.
The feature of this device is that when the raw material falls, the spacer is shaped like an inverted funnel installed to create a gap slightly wider than the size of the raw material resin between the raw material hopper and the inclined inner wall below it. It is composed of a portion fixed to the lid portion of the hopper and suspended so as not to substantially vibrate. The width of the gap is 1.5 to 7 times, preferably 2 to 5 times the maximum length of the raw material resin to be used. If this gap is 7 times or more, the effect of preventing segregation is reduced, and if it is 1.5 times or less, there is a risk that the raw material resin is deposited. Furthermore, the volume of the hopper below the lower part of the apparatus is preferably such that the time for the raw material to pass is 5 minutes or less. If there is a passage time of 5 minutes or more, there is a risk of segregation after the raw resin passes through the gap.

  The length of the gap in the direction in which the raw material descends is not particularly specified, but is preferably 10 cm or less at the maximum because the narrowest part is less likely to prevent the lowering of the raw material. The gap may be installed at two or more locations in the vertical direction of the hopper, but the segregation preventing effect is sufficient at one location, and the structure is simple and preferable. The angle of the umbrella of the suspended part is 40 degrees or more with respect to the horizontal direction, and more preferably 50 degrees or more. If it is less than 40 degrees, the flow of the raw material resin is deteriorated and the effect of preventing segregation is weakened. The angle of the inclined inner wall of the raw material hopper adjacent to the tip of the umbrella portion is preferably 40 degrees or more, and more preferably 50 degrees or more with respect to the horizontal direction. If this angle is less than 40 degrees, the flow of the raw material resin is deteriorated and the effect of preventing segregation is weakened.

  The components constituting the composition having a uniform resin mixing ratio obtained by the above method are supplied to the film forming extruder to form a film.

The feature of the method for producing the surface-protective polypropylene resin film of the present invention is as follows:
(1) Control of crystallinity in control of cooling condition of molten resin (2) Draft ratio control during take-up / cooling and solidification of molten resin (3) Thickness control in film width direction during take-up / cooling and solidification of molten resin is there.

[Control of crystallinity in cooling condition control]
The extruded film of the present invention is an unstretched film formed by a T-die method, and the thickness of the film is not particularly limited, but is generally 1 to 500 μm, and a film having a preferred thickness is necessary. Selected.
Film forming conditions for using the polypropylene resin composition of the present invention as an extruded film are preferably performed at a die temperature of 200 ° C to 250 ° C and a cooling roll temperature of 40 to 65 ° C. 45-60 degreeC is more preferable. If the cooling roll temperature is less than 40 ° C., a crystallinity sufficient for heat-resistant dimensional stability cannot be obtained, which is not preferable. Conversely, when the temperature exceeds 65 ° C., a touch roll mark of the cooling roll is generated, which is not preferable, and the transparency may be extremely lowered. Moreover, although it does not specifically limit about cooling time, The range for 0.5 second or more is preferable. If the cooling time is less than 0.5 seconds, the cooling effect is insufficient, and a touch roll mark of the cooling roll is generated, which is not preferable. On the other hand, the upper limit of the cooling time is not particularly limited from the viewpoint of the crystallinity of the film, but is more preferably 5 seconds or less, and more preferably 2 seconds or more from the viewpoint of economy and productivity. Moreover, when setting temperature low, it can also be made into 3 seconds or more.
When a crystal nucleating agent is used in combination as a means for arbitrarily adjusting the degree of crystallinity, it is necessary to add 100 ppm or less because there is a concern about an increase in fish eye of the film as described above. Therefore, the inventors found the control of the crystallinity by controlling the cooling conditions of the molten resin according to the cooling conditions.

[Draft ratio control]
The extruded film of the present invention has a draft ratio of 0.4 to 3.0 in the drawing step after melt extrusion.
By adjusting to this range, the birefringence of the film can reach a predetermined range. It is generally known that the draft ratio is calculated according to the following film forming conditions.
Draft ratio = (film take-up speed / die exit melt resin speed) / air gap The air gap means the distance (cm) from the die exit to the take-up (cooling) roll contacting the melt resin.
When the draft ratio is less than 0.4, the thickness unevenness of the film increases, and the flatness of the film is deteriorated during the adhesive processing, which is not preferable. On the other hand, when the draft ratio exceeds 3.0, the birefringence exceeds the predetermined range, the impact resistance is remarkably lowered, and the mechanical properties of the film itself are deteriorated.

[Film width direction thickness control]
As a method for controlling the thickness in the film width direction, there is a method of adjusting the lip gap of the die manually or automatically. As a method of reducing the thickness variation in a shorter time, a method of automatically adjusting the lip gap by a mechanical or heat bolt method is preferable. In addition, it is necessary to adjust the conditions of the air chamber in order to suppress the thickness variation in the width direction to 10% or less. The air chamber is a device that blows air onto the resin film that has landed on the cooling roll to bring it into close contact with the cooling roll, but when the air leaks from the gap between the upper part of the air tumbler and the cooling roll when blowing air, The resin film before coming into contact with the cooling roll causes undulations and the thickness in the film width direction varies. Therefore, it is necessary to keep the wind pressure in the air chamber constant in the width direction and not to raise the absolute value of the wind pressure more than necessary. The air pressure in the air chamber is preferably 20 mmHg or less, although it depends on the film take-up speed.

  The extruded film of the present invention can be subjected to surface treatment such as corona discharge treatment or flame treatment by a method generally employed industrially.

  In the present invention, it is important that the surface protective film is a surface protective film in which an adhesive layer is provided on at least one surface of the above-described surface protective polypropylene-based resin film. By the correspondence, the characteristics of the polypropylene resin film of the present invention described above can be effectively utilized, and the applicability in a wide field as a protective film is improved. In particular, for example, applications that prevent scratches, adhesion of dirt, contamination, etc. during the processing and assembly of electronic and precision products such as liquid crystal panels and polarizing plates, precision products, parts and related members, and connection of flexible printed circuit boards As a method of partially plating the terminal part, etc., a mask is formed by sticking an adhesive film to the non-plated part and then plating, or a resist film or etching resistance provided on the non-etched surface in the etching process when manufacturing the shadow mask Use in plating and etching processes such as methods for protecting the film, methods for protecting the surface of the semiconductor element by laminating a film on the surface without the circuit of the semiconductor element, and simplifying the process when assembling the semiconductor device, etc. Protection of various precision products and parts that are particularly demanding to suppress contamination and defects, and addition of such products and parts It can be suitably used as a protective film in and assembly process. Further, the polypropylene resin film of the present invention is excellent in heat-resistant dimensional stability, and in the above-mentioned adhesive processing, for example, even if the drying temperature in the drying process is increased, the occurrence of hot stagnation and film sagging is suppressed. It becomes possible to increase the productivity of adhesive processing. Moreover, generation | occurrence | production suppression of the inferior goods resulting from a hot bath or film sagging can be suppressed.

  The kind, thickness, adhesive strength, and the like of the pressure-sensitive adhesive layer are not limited. What is necessary is just to select suitably by market demand. Moreover, the lamination method of this adhesive layer is not limited. Any of the coating method and the extrusion laminating method may be used.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited by the following examples, but may be implemented with appropriate modifications within a scope that can meet the gist of the present invention. These are all included in the technical scope of the present invention.

1. Melt flow rate [MFR]
According to JIS K7210, the method of Condition-14 (load 2.16 kg, temperature 230 ° C.
Measured with

2. Ethylene content Measured by 13C-NMR method according to the method described on page 616 of Polymer Handbook (1995, published by Kinokuniya Shoten)

3. Ratio of xylene soluble part at 20 ° C (%)
After 5 g of the sample was completely melted in 500 ml of boiling xylene, the temperature was lowered to 20 ° C. and left for 4 hours or more. Thereafter, the precipitate and the solution were separated by filtration, and the filtrate was dried and dried at 70 ° C. under reduced pressure. From the mass of the obtained dried product, the 20 ° C. xylene-soluble part amount was measured, and the ratio was determined.

4). Film crystallinity Measured using wide-angle essence line diffraction transmission method (RIGAKU RINT2500).

5. Coefficient of dynamic friction The seal layer surfaces of the films were combined, and the slip property was measured according to JIS-K7215-1987.

6). Thickness variation rate Based on JIS K7130, a 1 m wide film sample was measured at a 3 cm pitch in the width direction using a linear gauge type SIS-6 manufactured by Ozaki Seisakusho, and an average thickness was calculated. Next, either the maximum value or the minimum value among the measured film samples was calculated by the following calculation formula using either one having a large difference from the average thickness.
Thickness variation rate (%) = | (average thickness) − (maximum value or minimum value) | / (average thickness) × 100

7). Young's modulus In accordance with JIS K7127, sample shape conforming to No. 1 type test piece (sample length 200 mm, sample width 15 mm, distance between chucks 100 mm), MD direction under conditions of crosshead speed 500 mm / min It measured at 23 degreeC about (film longitudinal direction).

8). Birefringence (△ n)
Using an Abbe refractometer, the refractive index Nx in the film flow direction and the refractive index Ny in the film flow direction and the orthogonal direction were measured and calculated using the following formula.
△ n = │Nx-Ny│

8. Fluctuation width of xylene soluble part at 20 ° C (%)
A sample of a 1 m wide film sample was sampled at a pitch of 3 cm in the width direction and in the longitudinal direction, the amount of 20 ° C. xylene soluble part was measured by the method described above, and the value obtained by subtracting the minimum value from the maximum value of 10 points Asked.

9. Heat deformation resistance The molded film was cut into 5 cm in the flow direction and 25 cm in the direction transverse to the flow direction, and the film pieces were horizontally placed in a 120 ° C. dry heat oven with both ends held by a metal frame. Heat-treated for minutes. Immediately after the heat treatment, the film was taken out from the oven and allowed to cool at room temperature for 30 minutes, and then the sag (elongation) state due to the weight of the film itself was visually observed in the following range.
○: No dripping or almost no dripping.
(Triangle | delta): A drooping state is observed slightly.
X: A hanging state is observed.

10. Wrinkle and Tarmi Evaluation (1)
The formation state of wrinkles and tarmi when the roll having a film length of 100 m was wound up with a slitter (SXR-140 type manufactured by Toshin Co., Ltd.) in a roll shape with a width of 1300 mm was visually observed.
○: Wrinkles and tarmi are not generated during running and winding.
Δ: Slight wrinkles and tarmi were observed during running or winding.
X: Wrinkles and tarmi were clearly observed during running or winding.

11. Wrinkle and Tarmi Evaluation (2)
After the film roll wound up in the above wrinkle / tarmi evaluation (1) was stored at a humidity of 50 RH% and a temperature of 23 ° C. for 30 days, the state of occurrence of wrinkle / tarmi was visually observed.
○: Wrinkles and tarmi are not generated.
Δ: Generation of wrinkles and tarmi was observed.
X: Generation of wrinkles and tarmi was clearly observed.

18. Distortion after Application of Adhesive “Coponil 8694” manufactured by Nippon Synthetic Chemical Co., Ltd. was applied using a Mayer bar so that the thickness of the adhesive was 3 to 5 μm, and then dried at 70 ° C. for 5 seconds. The film after application of the adhesive was spread on a flat place, and the presence or absence of distortion was visually confirmed.
○: No distortion Δ: Slightly distortion ×: Distortion

12 Film whitening After the sheet was bent 180 ° to make crease lines, the presence or absence of whitening of the bent portion when expanded was visually determined.
A: There is no whitening.
○: Slight whitening was observed.
Δ: Whitening was observed.
X: Whitening was clearly observed.

13. Haze Based on JIS-K-6714, it was measured using “Haze Tester J” manufactured by Toyo Seiki Seisakusho.

14 Blocking resistance In accordance with ATM-D1893-67, a load of 90N was applied to the area of A4 size and left for 2 hours in an atmosphere of 60 ° C. After removing the load, the peeling resistance with a φ5 aluminum rod was measured at a moving speed of 100 mm / min. It measured on condition of this.

15. Impact strength In accordance with ASTM D3420, the sample is cut to 55-60 cm in the vertical direction and 9-10 cm in the horizontal direction. Read the strength value when punched using an impact tester in a 23 ° C room to the first decimal place. The operation is repeated 10 times, and the average value is obtained.

16. Fisheye The molded film was cut 33.3 cm in the flow direction × 30 cm in the direction transverse to the flow direction, placed on a plate irradiated with a fluorescent lamp from below the film, and visually observed with transmitted light. Measure fish eyes of 1 mm or more. Next, if the counted fish eye is immersed in liquid nitrogen and hardened, it is cut in half with a razor and the cross section of the fish eye is observed with a microscope at 50 to 300 times. For example, if there is no foreign matter such as cellulose, it is an unmelted lump, a lump due to gelation of a part of the raw material, or a gel-induced fish such as lump due to partial deterioration of the material during molding. Judged as eye. If there is a nucleus, it is judged as a fish eye caused by a foreign object and excluded from the count.

Example 1
69 parts by weight of homopolypropylene resin (MFR = 7), 22 parts by weight of block copolymerized polypropylene resin (MFR = 2) having a rubber component amount of 13.0% and an ethylene content of 6.5%, manufactured by Mitsui Chemicals, Inc. An acrylate antioxidant comprising a homopolypropylene resin (MFR = 7) containing 7 parts by weight of an elastomer (trade name: TAFMER P0480) and 5% by weight of Sumizer GS (manufactured by Sumitomo Chemical Co., Ltd.) which is an acrylate antioxidant. 2 parts by weight of a masterbatch resin containing selenium is melt-extruded by a T-die film forming machine with a heat bolt type automatic thickness control function, and a cooling roll temperature of 60 ° C. and a cooling time of 2.0 seconds (film forming speed 60 m / Min), draft ratio at the time of taking molten resin 1.56 (die slip gap: 0.5 mm, die slip outlet molten resin speed: 4.8 m / min) Air gap: 8 cm), to give an unstretched film having a thickness of 40μm by an air chamber air pressure 10mmHg of deposition conditions. The resin temperatures in the supply zone, kneading zone and metering zone of the extruder were set to 230, 240 and 235 ° C, respectively. The results are shown in Table 1.
The polypropylene-based resin film obtained in this example was good in all properties shown in Table 1 and high in quality.

(Example 2)
0.15% by mass of Irgafos 168 (manufactured by Ciba Specialty Chemicals Co., Ltd.) as a phosphorous antioxidant and 0 of Irganox 1010 (manufactured by Ciba Specialty Chemicals Co., Ltd.) as a phenolic antioxidant Random copolymerization of block copolymer polypropylene resin (MFR = 2) with an ethylene content of 3.0% and an ethylene content of 3.0% with an ethylene content of 13.0% and an ethylene content of 6.5% A polypropylene resin film of Example 2 was obtained in the same manner as in Example 1 except that 5 parts by weight of polypropylene resin (MFR = 7) was added and the cooling roll temperature was 45 ° C. The results are shown in Table 1.
The polypropylene-based resin film obtained in this example was good in all properties shown in Table 1 and high in quality.

(Example 3)
0.15% by mass of Irgafos 168 (manufactured by Ciba Specialty Chemicals Co., Ltd.) as a phosphorous antioxidant and 0 of Irganox 1010 (manufactured by Ciba Specialty Chemicals Co., Ltd.) as a phenolic antioxidant 0.15% by mass of homopolypropylene resin (MFR = 7) 85.5 parts by weight, Mitsui Chemicals, Inc. elastomer (trade name: Toughmer P0480) 14.5 parts by weight, cooling roll temperature 50 ° C., The same method as in Example 1 except that the draft ratio at the time of taking the molten resin was 2.50 (die slip gap: 0.8 mm, die slip outlet molten resin speed: 3.0 m / min, air gap: 8 cm) Thus, a polypropylene resin film of Example 3 was obtained. The results are shown in Table 1.
The polypropylene resin film obtained in this example had the same properties as the polypropylene resin film obtained in Example 1 and was of high quality.

Example 4
73 parts by weight of homopolypropylene resin (MFR = 7), 23 parts by weight of block copolymerized polypropylene resin (MFR = 2) having a rubber component amount of 13.0% and an ethylene content of 6.5%, manufactured by Mitsui Chemicals, Inc. An acrylate antioxidant comprising a homopolypropylene resin (MFR = 7) containing 12 parts by weight of an elastomer (trade name: TAFMER P0480) and 5% by weight of Sumizer GS (manufactured by Sumitomo Chemical Co., Ltd.) as an acrylate antioxidant. 2 parts by weight of the masterbatch resin containing is fed into an extruder from a raw material hopper equipped with a segregation prevention device, and melted and extruded by a T-die film forming machine with a heat bolt type automatic thickness control function. , A cooling roll temperature of 60 ° C., a cooling time of 2.0 seconds (film formation speed of 60 m / min), a draft ratio of 1.56 when the molten resin is taken up (die-slip Gap: 0.5 mm, die lip outlet molten resin Speed: 4.8 m / min, air gap: 8 cm) to obtain an unstretched film having a thickness of 40μm by an air chamber air pressure 10mmHg of deposition conditions. The resin temperatures in the supply zone, kneading zone and metering zone of the extruder were set to 230, 240 and 235 ° C, respectively. Moreover, thickness control in the width direction was performed. The results are shown in Table 1.
The polypropylene-based resin film obtained in this example was good in all properties shown in Table 1 and high in quality.

(Example 5)
0.15% by mass of Irgafos 168 (manufactured by Ciba Specialty Chemicals Co., Ltd.) as a phosphorous antioxidant and 0 of Irganox 1010 (manufactured by Ciba Specialty Chemicals Co., Ltd.) as a phenolic antioxidant 90 parts by weight of a homopolypropylene resin (MFR = 7) containing 15% by mass and 10 parts by weight of an elastomer (trade name: Toughmer P0480) manufactured by Mitsui Chemicals, Inc., cooling roll temperature 50 ° C., drawing of molten resin Example 2 was prepared in the same manner as in Example 4 except that the draft ratio was 2.50 (die slip gap: 0.8 mm, die slip outlet molten resin speed: 3.0 m / min, air gap: 8 cm). A polypropylene resin film was obtained. The results are shown in Table 1.
The polypropylene resin film obtained in this example had the same characteristics as the polypropylene resin film obtained in Example 4 and was of high quality.

(Example 6)
A polypropylene resin film of Example 6 was obtained in the same manner as in Example 4 except that the material resin was melted by feeding into an extruder from a raw material hopper not equipped with a segregation prevention device. The results are shown in Table 2.

(Comparative Example 1)
30 parts by weight of a random copolymer polypropylene resin (MFR = 7) having an ethylene content of 0.5% by mass, and 0.22 mass of Irgafos 168 (manufactured by Ciba Specialty Chemicals Co., Ltd.) as a phosphorus-based antioxidant % Of the rubber component containing 0.28% by mass of Irganox 1010 (manufactured by Ciba Specialty Chemicals Co., Ltd.) as a phenolic antioxidant and 8.5% ethylene content and 5.0% ethylene content A polypropylene resin film of Comparative Example 2 was obtained in the same manner as in Example 1 except that 70 parts by weight of block copolymerized polypropylene resin (MFR = 2) was blended. The results are shown in Table 2.
In the polypropylene resin film obtained in this comparative example, wrinkles and tarmi occurred during film roll storage.

(Comparative Example 2)
98 parts by weight of a random copolymer polypropylene resin (MFR = 7) having an ethylene content of 0.5% by mass, and bis (2,2′-methylene-bis (4,6-ditertiary) as a cyclic organophosphate compound Butylphenyl) phosphate) -aluminum hydroxide salt (manufactured by Asahi Denka Kogyo Co., Ltd., Adeka Stub NA-21) 1% by weight of a master batch resin (MFR) containing a crystal nucleating agent comprising a homopolypropylene resin (MFR = 7) -1) 1 part by weight, a masterbatch containing an acrylate antioxidant comprising a homopolypropylene resin (MFR = 7) containing 5% by weight of Sumilizer GS (manufactured by Sumitomo Chemical Co., Ltd.) which is an acrylate antioxidant 1 part by weight of resin is blended, melt extrusion is performed with a T-die film forming machine, cooling temperature is 45 ° C., cooling time is 3.0 seconds (film forming speed 40 m / min), draft ratio when taking molten resin 1.60 (die slip gap: 0.5 mm, die slip outlet molten resin speed: 8.0 m / min, air gap: 8 cm) An unstretched film having a thickness of 100 μm was obtained. The results are shown in Table 2. The polypropylene resin film obtained in this comparative example also generated wrinkles and tarmi during film roll storage.

(Comparative Example 3)
0.15% by mass of Irgafos 168 (manufactured by Ciba Specialty Chemicals Co., Ltd.) as a phosphorous antioxidant and 0 of Irganox 1010 (manufactured by Ciba Specialty Chemicals Co., Ltd.) as a phenolic antioxidant Comparison was made in the same manner as in Example 1 except that 100 parts by weight of a block copolymer polypropylene resin (MFR = 2) having a rubber component content of 11.0% and an ethylene content of 20% containing 18% by mass was blended. The polypropylene resin film of Example 3 was obtained. The results are shown in Table 2.
The polypropylene resin film obtained in this comparative example did not have sufficient heat distortion resistance.

(Comparative Example 4)
A polypropylene resin film of Comparative Example 4 was obtained in the same manner as in Example 1 except that the air chamber wind pressure was 40 mHg. The results are shown in Table 2.
In the polypropylene resin film obtained in this comparative example, wrinkles and tarmi occurred during film roll storage.

(Comparative Example 5)
Homopolypropylene containing 97 parts by weight of a random copolymerized polypropylene resin (MFR = 7) having an ethylene content of 0.5% by mass and 5% by weight of Sumizer GS (manufactured by Sumitomo Chemical Co., Ltd.) which is an acrylate antioxidant Example 1 except that 1 part by weight of a masterbatch resin containing an acrylate antioxidant made of resin (MFR = 7) and 2 parts by weight of an elastomer (trade name: Toughmer P0480) manufactured by Mitsui Chemicals, Inc. were blended. The polypropylene resin film of Comparative Example 5 was obtained by the method. The results are shown in Table 2.
The polypropylene resin film obtained in this comparative example was easily whitened and inferior in heat deformation resistance, and wrinkles and tarmi occurred during film roll storage.

(Comparative Example 6)
0.22% by mass of Irgafos 168 (manufactured by Ciba Specialty Chemicals Co., Ltd.) as a phosphorous antioxidant and 0 of Irganox 1010 (manufactured by Ciba Specialty Chemicals Co., Ltd.) as a phenolic antioxidant 22 parts by weight of a block copolymerized polypropylene resin (MFR = 7) having a rubber component content of 13% and an ethylene content of 6.5% containing 28% by mass, 57 parts by weight of a homopolypropylene resin (MFR = 7), Mitsui It is composed of a homopolypropylene resin (MFR = 7) containing 2 parts by weight of an elastomer (trade name: Toughmer P0480) manufactured by Chemical Co., Ltd. and 5% by weight of a acrylate antioxidant, Sumilizer GS (manufactured by Sumitomo Chemical Co., Ltd.). 1 part by weight of a masterbatch resin containing an acrylate antioxidant is blended, and segregation prevention is performed as in Example 1. 2. Feed into an extruder from a raw material hopper equipped with an apparatus, melt and extrude with a T-die film forming machine with a heat bolt type automatic thickness control function, cooling time at 45 ° C. and cooling time 3. 0 seconds (film forming speed 40 m / min), draft ratio at the time of taking molten resin 0.63 (die slip gap: 0.5 mm, die slip outlet molten resin speed: 8.0 m / min, air gap: 8 cm) An unstretched film having a thickness of 100 μm was obtained under the film forming conditions. The results are shown in Table 2. The polypropylene resin film obtained in this comparative example was distorted after the adhesive was applied.

(Comparative Example 7)
A polypropylene resin film of Comparative Example 7 was obtained in the same manner as in Example 4 except that thickness control in the width direction was not performed. The results are shown in Table 2.
In the polypropylene resin film obtained in this comparative example, wrinkles and tarmi were generated during film running and during film roll storage.

(Reference Example 1)
In the method of Comparative Example 1, a polypropylene resin film of Reference Example 3 was obtained in the same manner as in Comparative Example 1, except that 5 parts by weight of the master batch resin (M-1) containing a crystal nucleating agent was added. The results are shown in Table 3.
The polypropylene resin film obtained in this reference example had a low quality because the fish eye increased significantly compared to the polypropylene resin film obtained in Comparative Example 1.

  The results are shown in Tables 1 and 2.

The present invention is excellent in heat-resistant dimensional stability and flatness, excellent in impact resistance and bonding processability, and is suitable as a base film for a protective film, for example.
Since the polypropylene resin film for surface protection of the present invention is excellent in heat-resistant dimensional stability, for example, it is suitable for secondary processing such as adhesive processing, and is particularly subjected to treatment such as drying at a high temperature around 130 ° C. In addition, since the occurrence of hot stagnation and film sagging is suppressed, the productivity of the secondary processing can be improved, and the generation of defective products due to hot sag and film sagging can be suppressed.
Further, the present invention has small thickness spots.
Moreover, it is preferable that the polypropylene resin film of the present invention does not substantially contain an antiblocking agent. For example, when a film containing an antiblocking agent is run, the antiblocking agent falls off due to wear or the like. Therefore, the contamination and the occurrence of troubles due to the fallout are suppressed.
In addition, although the present invention does not substantially contain a lubricant or an anti-blocking agent, the surface roughness is appropriate, the slipperiness and blocking resistance of the film are good, and the film is excellent in rigidity. Is easy to handle.
Moreover, since it is excellent in transparency, it is excellent in the visibility of a to-be packaged object or a to-be-protected body.
In addition, because of the strength of the film, it is excellent in handleability.
In addition, despite its improved heat-resistant dimensional stability, it has excellent impact strength and maintains good impact resistance by being made of block polypropylene resin. High reliability when there is.

Claims (8)

  A polypropylene-based resin film containing a polypropylene-based resin as a main component, wherein the 20 ° C. xylene soluble part is more than 9% and less than 16%, and the content of the crystal nucleating agent is 100 ppm or less. A surface-protective polypropylene-based resin film having a thickness variation rate in the width direction of 1% or more and 10% or less, a dynamic friction coefficient of 1.0 or less, and a tensile elastic modulus of 500 MPa or more and 900 MPa or less.   The surface-protective polypropylene resin film according to claim 1, wherein the content of the antiblocking agent in the film is 50 ppm or less and the blocking resistance is 10 mN or less. The number of fish eyes having a maximum diameter of 0.2 mm or more in the film is 0 / m ² and the number of fish eyes having a maximum diameter of less than 0.2 mm is 100 / m ² or less. The polypropylene resin film for surface protection according to 1.   The surface-protective polypropylene-based resin film according to claim 1, wherein the film has a longitudinal Young's modulus at 23 ° C. of 500 Mpa or more.   The polypropylene resin film for surface protection according to claim 1, wherein the impact strength of the film at 23 ° C. is 0.3 J or more.   The film comprises at least an acrylate antioxidant and at least one antioxidant selected from a phosphorus antioxidant and a phenolic antioxidant. The polypropylene resin film for surface protection according to 1.   2. The polypropylene resin film for surface protection according to claim 1, wherein the rate of fluctuation of the 20 ° C. xylene-soluble part of the film is 2% or less.   A surface protective film comprising a pressure-sensitive adhesive layer on at least one surface of the surface-protective polypropylene-based resin film according to claim 1.