JP6507785B2 - Film for surface protection - Google Patents

Description

  The present invention relates to a film, and to a film for surface protection which achieves both supportability and releasability.

  The film for surface protection is used for the purpose of protecting the surface of various members, such as a circuit member, a display member, and a medical member.

  In recent years, high definition and thickness reduction of each member have been advanced, and there is an increasing demand for improving the protection and handleability of the member by providing the surface protection film with a supportability. When the surface protective film is made rigid in order to give support to the surface protective film, the peelability is lowered, and there is a problem that peeling can not be performed well. Therefore, there is an urgent need to develop a new film for surface protection that combines supportability and releasability.

  As a film for surface protection which is excellent in releasability, the adhesion film which made the adhesion power of an adhesion layer, the surface coarseness of a exfoliation layer, and flexural rigidity a specific range is indicated (for example, patent documents 1). In addition, a sheet for protecting the surface of a semiconductor wafer, which defines the storage elastic modulus at each temperature, is disclosed (for example, Patent Document 2).

JP 2008-231352 A WO 2006/88074

  Although the film for surface protection described in Patent Document 1 has good releasability, the supportability is not a design considered so much, and the supportability is insufficient. Moreover, although the film for surface protections of patent document 2 has thick film thickness and supportability can be ensured, it did not consider about peelability.

  An object of the present invention is to solve the above-mentioned problems. That is, it is providing a new film for surface protection which makes supportability and releasability compatible.

The present invention adopts the following means in order to solve the problems.
(1) the following expressions sought stiffness constant of 1.00 N · mm or more, the bending stiffness is determined by loop stiffness test method Ri der less 0.040N / 5mm, a Young's modulus of 2,000 N / mm ² or more It has 4,000 N / mm ² or less, and has a layer (A layer) containing a polyester resin as a main component and a layer (B layer) containing a polyolefin resin as a main component, and the polyester resin is polyethylene It is a terephthalate, The said A layer made 80 mass% or more and 100 mass% or less of polyester resin with the whole layer being 100 mass%, and the said B layer made all the components in the said B layer 100 mass%. Occasionally, as the polyolefin resin include polyethylene resin 50% by mass or more, and characterized in that it comprises an acid-modified polyethylene resin, Table Protective film.
Stiffness (N · mm) = Young's modulus (N / mm ² ) × (film thickness (mm)) ³
(2) The film for surface protection described in (1) , characterized in that the breaking elongation of the film at 25 ° C. is 50% or more.
(3) The film for surface protection as described in (1) or (2) characterized by film haze being 5.0% or less.
(4) The film for surface protection according to any one of (1) to (3) , wherein the layer A / layer B / layer A is directly laminated in this order.
(5) The composition formed by laminating a film for surface protection given in either of (1)- (4) on at least single side of a covering object.
(6) wherein the surface protective film and the adherend, characterized in that it is laminated via an adhesive layer, construction according to (5).
(7) The structure according to (5) or (6) , wherein the peel strength between the adherend and the film for surface protection is 0.01 N / 25 mm or more and 5.00 N / 25 mm or less. .

  According to the present invention, it is possible to provide a film for surface protection having both supportability and releasability. The film for surface protection of the present invention can be applied to high definition and thin members, and can be preferably used for circuit members, display members, medical members and the like.

The film for surface protection of the present invention has a rigidity of 1.00 N · mm or more, which is determined by the following equation, in order to achieve both supportability and releasability, and a flexural rigidity of 0.040 N which is determined by a loop stiffness test method. It is important that it is / 5 mm or less.
Stiffness (N · mm) = Young's modulus (N / mm ² ) × (film thickness (mm)) ³
The film for surface protection of the present invention has a rigidity determined by Young's modulus (N / mm ² ) × (film thickness (mm)) ³ from the viewpoint of securing sufficient supportability to be applied to high definition and thin members. It is important that the rate (N · mm) is 1.00 N · mm or more. Furthermore, from the viewpoint of achieving both the supportability and the releasability of the film for surface protection, the rigidity is more preferably 1.20 N · mm or more, and particularly preferably 1.40 N · mm or more. The upper limit of the rigidity is not particularly limited as long as the effects of the present invention are not impaired. However, to obtain the effects of the present invention, 5.00 N · mm is sufficient and the upper limit is 2. More preferably, it is 00 N · mm.

  From the viewpoint of securing sufficient releasability of the film for surface protection of the present invention, it is important that the flexural rigidity determined by the loop stiffness test method is 0.040 N / 5 mm or less. Furthermore, from the viewpoint of achieving both the supportability and the releasability of the film for surface protection, the flexural rigidity is more preferably 0.030 N / 5 mm or less, and particularly preferably 0.025 N / 5 mm or less. The lower limit of the bending rigidity is not particularly limited as long as the effects of the present invention are not impaired, but 0.005 N / 5 mm is sufficient to obtain the effects of the present invention, and 0.010 N / 5 mm or more It is more preferable that

In the film for surface protection of the present invention, the method for setting the rigidity to 1.00 N · mm or more is not particularly limited, and examples thereof include methods for adjusting the film thickness and Young's modulus. The rigidity is proportional to the cube of the film thickness and thus increases as the film thickness is increased. The film thickness is preferably 40 μm or more and 200 μm or less, more preferably 50 μm or more and 150 μm or less, and particularly preferably 70 μm or more and 100 μm or less from the viewpoint of achieving both rigidity and handleability and economy. In addition, since the rigidity is also proportional to the Young's modulus, it can be increased by using a resin having a high Young's modulus, such as a polyester resin. From the viewpoint of handling properties, the Young's modulus of the surface protective film of the present invention, 2,000 N / mm ² or more 4,000N / mm ² or less der Rukoto is important, 2,200N / mm ² or more 3, more preferably, if 800 N / mm ² or less, and most preferably equal to 2,500 N / mm ² or more 3,500Nmm ² or less.

In the surface protective film of the present invention, in the bending rigidity 0.040N / 5mm or less, it is important to have a layer of a low glass transition temperature resin as a main component. Specifically, it is important to have a layer whose main constituent component is a resin having a glass transition temperature of 60 ° C. or less, and a layer whose main constituent component is a resin whose glass transition temperature is 50 ° C. or less Is preferred. Layer the glass transition temperature is lower resin as a main component, from the viewpoint of versatility, it is important that the polyolefin resin is a layer whose main constituent. Here, the term "main component" as used herein means that when the entire layer is 100% by mass, it occupies 80% by mass or more.

In the film for surface protection of the present invention, in order to set the flexural rigidity to 0.040 N / 5 mm or less and to set the rigidity to 1.00 N · mm or more, a layer (A layer) containing a polyester resin as a main component It is important to have a layer (B layer) mainly composed of a polyolefin resin. In general, polyester resins have a high Young's modulus, so the rigidity can be easily controlled to be high, while polyolefin resins can be easily controlled to have low bending rigidity. For this reason, it becomes easy to control coexistence of flexural rigidity 0.040 N / 5 mm or less and rigidity 1.00 N * mm or more by having A layer and B layer.

  In the film for surface protection of the present invention, the layer A is a layer containing a polyester resin as a main component. Here, having a polyester-based resin as a main constituent component means that the entire layer is 100% by mass, and the polyester-based resin is contained at 80% by mass to 100% by mass.

Here, the polyester-based resin is a generic term for a polymer compound having an ester bond in the repeating unit of the main chain. The polyester resin can be generally obtained by subjecting a dicarboxylic acid or its derivative and a glycol or its derivative to a polycondensation reaction. Here, the dicarboxylic acid unit (structural unit) or the glycol unit (structural unit) means a divalent organic group excluding a portion removed by polycondensation, and is represented by the following general formula.
Dicarboxylic acid unit (structural unit): -CO-R-CO-
Glycol unit (structural unit): -O-R'-O-
(Here, R and R 'are divalent organic groups. R and R' may be the same or different.)
The same applies to the meaning of a unit (structural unit) of a trivalent or higher carboxylic acid such as trimellitic acid unit and glycerin unit, or alcohol, and derivatives thereof.

It is important that the polyester resin in the film for surface protection of the present invention is a polyethylene terephthalate resin from the viewpoints of supportability, peelability, handleability and economy.

Here, the polyethylene terephthalate resin is a polyester resin composed of ethylene glycol as a glycol or its derivative, and composed of terephthalic acid as a dicarboxylic acid or its derivative. In addition, ethylene glycol and terephthalic acid may be copolymerized with other glycols or derivatives thereof and other dicarboxylic acids or derivatives thereof as long as the object of the present invention is not impaired. Specifically, as a glycol component or a derivative thereof, ethylene glycol is 90 mol% or more and 100 mol% or less, more preferably 95 mol% or more and 100 mol% or less, and most preferably 98 mol% or more and 100 mol% or less . Further, as the dicarboxylic acid component or its derivative, terephthalic acid is 90 mol% or more and 100 mol% or less, more preferably 95 mol% or more and 100 mol% or less, and most preferably 98 mol% or more and 100 mol% or less. As the layer (A layer) to the polyester resin as a main component, supporting, from the viewpoint of peeling resistance, a biaxially oriented polyethylene terephthalate film is more preferably used.

In the present invention, it is important that the B layer contains a polyolefin resin as a main component. Here, having a polyolefin resin as a main constituent component means that the entire B layer is 100 mass% and 80 mass% or more of the polyolefin resin is contained.

  Here, as the polyolefin resin, specifically, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, ethylene-α-olefin copolymer polymerized using a metallocene catalyst, polypropylene Polyolefin resins such as ethylene-propylene copolymer, ethylene-propylene-butene copolymer, and methylpentene polymer can be used. Further, a polymer comprising an α-olefin monomer such as ethylene, propylene, butene-1, pentene-1, 4-methylpentene-1, hexene-1 and octene-1, a random copolymer comprising the α-olefin monomer Also, a block copolymer comprising such an α-olefin monomer can be used.

  As a random copolymer consisting of such an α-olefin monomer, for example, in the case of a propylene copolymer, propylene and at least one α-olefin monomer except for propylene from the above α-olefin monomers are randomly Examples of the polymer include polymerized polypropylene, which is copolymerized with 2 to 15% by mass of one or more α-olefin monomers except propylene by a known method.

  Moreover, as a block copolymer which consists of the above-mentioned alpha-olefin monomer, for example, in a propylene ethylene block copolymer, propylene in the range of 99 to 70% by mass and ethylene in the range of 1 to 30% by mass and / Or a copolymer of an α-olefin and a copolymer of 1 to 30% by mass of propylene and 99 to 70% by mass of ethylene is used. be able to. The composition of each copolymer component, the molecular weight of each block, etc. can be controlled at the polymerization stage. Generally, it can be obtained by two or more stages of polymerization methods as shown in JP-A-59-115312. For example, the melting point of the propylene-ethylene block copolymer is in the range of 145-165 ° C. The melting point can be changed by the amount of propylene component of the copolymer portion consisting of propylene in the range of 99 to 70% by mass and ethylene and / or α-olefin in the range of 1 to 30% by mass. In addition, the amount of ethylene component and / or the amount of α-olefin component in the propylene / ethylene / block copolymer is preferably 5 to 20% by mass, more preferably 5 to 15% by mass in terms of the impact resistance of the film. %. In the present invention, the method for producing the polyolefin resin is not particularly limited, and any known method can be used. For example, in the case of polypropylene resin, radical polymerization, coordination polymerization using a Ziegler-Natta catalyst, anionic polymerization And any method such as coordination polymerization using a metallocene catalyst.

The film for surface protection of the present invention has a polyethylene-based resin of 50 as the polyolefin-based resin when all components in the layer B are 100% by mass from the viewpoint of supportability, peelability, handleability and economy. It is important to contain by mass% to 100 mass% , and it is more preferable to contain 70 mass% to 100 mass% in total , and it is particularly preferable to contain 80 mass% to 100 mass%.

  In the film for surface protection of the present invention, the breaking elongation of the film at 25 ° C. is preferably 50% or more, more preferably 75% or more, and preferably 90% or more, from the viewpoint of toughness during film transport. Is particularly preferred. By setting the breaking elongation of the film at 25 ° C. to 50% or more, breakage does not occur even if the transport tension of the film is increased, and productivity is improved, which is preferable. The upper limit of the elongation at break of the film at 25 ° C. is not particularly limited as long as the effects of the present invention are not impaired, but about 200% is sufficient. Here, the breaking elongation of the film means the average of the breaking elongation in the film longitudinal direction and the breaking elongation in the film width direction. The film longitudinal direction refers to the direction in which the film travels during film production, and the film width direction refers to a direction parallel to the transport surface of the film and orthogonal to the film longitudinal direction. Hereinafter, the film longitudinal direction may be referred to as the longitudinal direction, and the film width direction may be referred to as the width direction.

The breaking elongation of the film in 25 ° C. of the surface protective film of the present invention as a method of 50% or more is not particularly limited as long as it does not impair the effects of the present invention, the interlayer adhesion between A layer and B layer It is preferable to make it high. When the adhesion between the layer A and the layer B is low, when the film is pulled, stress may concentrate on the interface between the layer A and the layer B, and the film may be easily broken. In order to set the film breaking elongation to 50% or more, the interlayer adhesion between layer A and layer B is preferably 5N / 15 mm or more, more preferably 10N / 15 mm or more, and 15N / 15 mm or more Most preferable.

  In the film for surface protection of the present invention, the method of laminating the layer A and the layer B is not particularly limited. For example, a method of laminating via an adhesive layer or an adhesive layer, a method of laminating by coextrusion, lamination by extrusion lamination And the like, but from the viewpoints of coexistence of supportability and releasability and economy, a method of laminating by extrusion lamination is preferably used. In the present invention, when the layer A is a biaxially oriented polyester film, the plane orientation coefficient of the layer A is preferably 0.130 or more and 0.180 or less from the viewpoint of supportability, and is preferably 0.140 or more. It is more preferably 0.177 or less, and particularly preferably 0.150 or more and 0.175 or less.

  In the present invention, as a method of enhancing the interlaminar adhesion between layer A and layer B by extrusion lamination of layer A to layer A, for example, a method of coating an easily adhesive layer on the surface of layer A, layer A And the like.

  As the method of coating the easy adhesion layer, any of a method of providing the layer A in-line in the process of producing a film of layer A, a method of providing a film of layer A after making offline and any method may be employed. When the layer A is a biaxially oriented polyester film, as a method of providing the easy adhesion layer in-line in the film production process, a film obtained by dispersing the coating layer composition in water on at least uniaxially stretched film is used as a meta It is preferable to apply uniformly using a ring ring bar or a gravure roll and to dry the coating agent while applying transverse stretching, in which case the thickness of the easy adhesion layer is 0.01 μm or more and 1 μm or less. preferable.

  In addition, various additives such as antioxidants, heat stabilizers, ultraviolet absorbers, infrared absorbers, pigments, dyes, organic or inorganic particles, antistatic agents, nucleating agents, etc. may be added to the adhesive layer. Good. It is preferable that it is at least 1 sort (s) of resin chosen from an acrylic resin, a polyester resin, and a urethane resin from the point of adhesiveness and handling property as resin used for an easily bonding layer.

  Further, in the present invention, the method of modifying the biaxially oriented polyester film is not particularly limited, but, for example, corona discharge treatment, ultraviolet irradiation treatment, plasma treatment, laser treatment, flame treatment, high frequency treatment, glow discharge Treatment, ozone oxidation treatment, etc. may be mentioned, and the surface free energy of the film surface after the modification treatment is preferably 50 mN / m or more.

It is important that the film for surface protection of the present invention contains an acid-modified polyethylene-based resin in the layer B from the viewpoint of enhancing the interlayer adhesion between the layer A and the layer B. Herein, the acid-modified polyethylene resin, will have a resin obtained by copolymerizing a component having a polarity at the end of the polyethylene resin. As a component which has polarity, carboxylic anhydride etc. can be used, for example. The content of the acid-modified polyethylene-based resin in the layer B is preferably 1% by mass to 50% by mass, based on 100% by mass of the whole layer B, and more preferably 2% by mass to 30% by mass. It is especially preferable if it is 3 mass% or more and 20 mass% or less.

  The film for surface protection of the present invention preferably has a film haze of 5.0% or less. By setting the film haze to 5.0% or less, the appearance and appearance when laminated on the surface of various members such as a circuit member, a display member, and a medical member become good. From the viewpoint of appearance and appearance, the film haze is more preferably 4.0% or less, and particularly preferably 3.0% or less. The lower limit of the film haze is not particularly limited as long as the effect of the present invention is not impaired, but 0.1% is sufficient.

  As a method of making the film haze of the film for surface protection of the present invention 5.0% or less, the method of lowering the film haze of the A layer and the B layer, the A layer and the B layer, the adhesive layer, the adhesive layer A direct lamination method is effective. The film haze of each of the layer A and the layer B is preferably 2.0% or less.

  As a method of lowering the film haze of the layer A, for example, when the layer A is a biaxially oriented polyester film, a method of reducing the concentration of particles to be contained to improve the transportability of the film can be mentioned. In the present invention, the layer A can contain particles in the film in order to improve the transportability of the film. Here, the particles to be used are not particularly limited, but in terms of transportability and appearance, externally added particles are preferably used. Examples of externally added particles include wet and dry silica, colloidal silica, aluminum silicate, titanium oxide, calcium carbonate, calcium phosphate, calcium phosphate, barium sulfate, inorganic particles such as aluminum oxide, styrene, silicone, acrylic acids, methacrylic acids, polyesters Organic particles having a divinyl compound or the like as a component can be used. Among them, inorganic particles such as wet and dry silica, alumina and calcium carbonate, and organic particles containing styrene, silicone, acrylic acid, methacrylic acid, polyester, divinylbenzene and the like are used from the viewpoint of handleability and film haze reduction. It is preferable to do. Furthermore, these externally added particles may be used in combination of two or more. From the viewpoint of transportability and appearance, the content of particles in the layer A is preferably 0.001 to 0.02 mass% based on 100% by mass of the entire film, and 0.002 to 0.01 mass%. More preferable.

In addition, although a biaxially oriented polyester film is mainly used as A layer, the particle content in this film can be calculated | required by centrifuging. That is, the particle content in the film can be determined by dissolving 10 g of the film in 100 g of orthochlorophenol and centrifuging the particles with the polyester to determine whether the film contains particles. In addition, the conditions of centrifugation are realizable by implementing for 40 minutes on condition of 40 degreeC and 8800 r / min using "Suprema 25" made from Tommy Seiko. Furthermore, if it is found that the particles are contained after centrifugation, the particle content can be determined by the following equation by determining its mass.
(Particle content) = (mass of particles) / (mass of whole film) × 100
Moreover, as a method of making the film haze of B layer low, the method of making a B layer contain copolyethylene resin and / or copolypropylene resin is mentioned, for example. Specifically, ethylene-propylene copolymer, ethylene-propylene-butene copolymer, ethylene-methacrylic acid copolymer, ethylene-hexene copolymer, etc. are preferably used as the resin to be contained in the layer B. The content of the copolymerized polyethylene-based resin and / or the copolymerized polypropylene-based resin in the layer B is preferably 10% by mass or more, based on 100% by mass of the whole layer B, from the viewpoint of film haze reduction, and 20% by mass It is more preferable if it is more than, and it is especially preferable if it is 50 mass% or more. The upper limit of the content of the copolymerized polyethylene-based resin and / or the copolymerized polypropylene-based resin in the layer B is not particularly limited as long as the effects of the present invention are not impaired. There is no problem as well.

  In addition, the film for surface protection of the present invention preferably has a configuration in which A layer / B layer / A layer is directly laminated in this order from the viewpoint of handleability and curl resistance.

  Next, although the example of the specific manufacturing method of the film for surface protections of this invention is described, this invention is not limited and interpreted as this example.

  First, the biaxially oriented polyester film surface is irradiated with ultraviolet light to make the surface free energy of the film 50 mN / m or more, and then the film surface is a polyolefin resin mixed with a copolymerized polyethylene resin and an acid-modified polyethylene resin. The sheet is discharged from a T-die. At that time, a biaxially oriented polyester film similar to the above biaxially oriented polyester film is laminated (biaxially oriented polyester film / polyolefin based resin layer / biaxially oriented polyester film) in a configuration in which a polyolefin resin layer is sandwiched (nip roll) After pressure-bonding with a metal roll cooled to 20 ° C., the film is cooled and solidified with a cooling roll to obtain a surface protection film of the present invention.

  The biaxially oriented polyester film used at this time is preferably 20 μm or more and 75 μm or less in film thickness, and more preferably 25 μm or more and 50 μm or less. The plane orientation coefficient of the biaxially oriented polyester film is preferably 0.130 or more and 0.180 or less, more preferably 0.140 or more and 0.177 or less, and still more preferably 0.150 or more and 0.175 or less. Are particularly preferable. Further, the film haze is preferably 2.0% or less. The polyolefin-based resin layer preferably has a thickness of 10 μm to 70 μm, more preferably 20 μm to 60 μm, and particularly preferably 30 μm to 50 μm. Moreover, it is preferable that film haze is 2.0% or less also as a polyolefin resin layer.

  The film for surface protection according to the present invention is a new film that achieves both supportability and releasability, and is laminated on at least one surface of an adherend using various members such as a circuit member, a display member, a medical member, etc. Preferably, it is used as a composite structure.

  It is preferable that the adherend and the film for surface protection are laminated | stacked through the adhesive layer from the viewpoint of peelability and the surface property after peeling the structure of this invention.

  The peel strength of the adherend and the film for surface protection is preferably 0.01 N / 25 mm or more and 5.00 N / 25 mm or less, and 0.02 N / 25 mm from the viewpoint of peelability and surface property after peeling. It is more preferably 3.00 N / 25 mm or less, and particularly preferably 0.05 N / 25 mm or more and 2.00 N / 25 mm or less.

  The method for setting the peel strength between the adherend and the film for surface protection to 0.01 N / 25 mm to 5.00 N / 25 mm is not particularly limited as long as the effects of the present invention are not impaired. For example, the type of adhesive layer is selected. And the method of adjusting the laminating temperature and pressure of the adherend and the film for surface protection. In the method of adjusting the laminating temperature and pressure of the adherend and the film for surface protection, the peel strength between the adherend and the film for surface protection becomes larger as the laminating temperature and pressure become higher.

  The adhesive layer is not particularly limited as long as the effects of the present invention are not impaired, but acrylic resins, copolyester resins, modified thermoplastic elastomers and the like are preferably used. Moreover, as the installation method of an adhesion layer, the method of using a die coater, a bar coater, a knife coater other than a roller coating method, a brush coating method, a spray coating method, a dip coating method is mentioned, for example.

  The conditions for the subsequent drying step may vary depending on the film thickness and the type of the selected solvent, but, for example, when an acrylic resin is used as the adhesive layer, the temperature should be 80 to 150 ° C. for 20 to 60 seconds. And preferably at 100 to 130 ° C. for 30 to 50 seconds. Thereby, the adhesion layer which has a thickness of 1-50 micrometers can be formed.

Hereinafter, the present invention will be described according to examples, but the present invention is not limited by these examples. Various properties were measured by the following methods. However, Example 10 is referred to as Reference Example 1.

(1) Using a film thickness dial gauge, measure the thickness of 5 arbitrary places of the sample cut out from the film, round the first decimal place of the average value and use the total thickness of the film (μm) did.

  The thickness of the layer A was measured by the same method as the total thickness of the film, and the thickness of the layer B was determined by subtracting the thickness of the layer A from the total thickness of the film.

(2) Young's Modulus An arbitrary one direction is X direction, a direction orthogonal to the X direction is Y direction, and a long side is a 150 mm × 10 mm rectangle, and a long side is Y 150 mm × 10 mm. The film was cut out and used as a sample. About the obtained sample, crosshead speed 300 mm / min, width 10 mm, sample length (distance between chucks) 50 mm using a tensile tester (Tensilon UCT-100 manufactured by Orientec Co., Ltd.) under conditions of 25 ° C. and 63% Rh. The tensile test was carried out as a tensile strain, and an elongation-stress curve was obtained in the X direction and the Y direction. In the obtained curve, Young's modulus was determined from the linear expression of the tangent of the maximum slope within 1% of elongation. The measurement was performed five times in both the X direction and the Y direction, and the value obtained by rounding off the first decimal place of the average value of all these values was taken as the Young's modulus (N / mm ² ).

(3) The overall thickness of the film determined by the rigidity (1) is taken as the film thickness, and from the film thickness and the Young's modulus determined by (2), the third decimal place of the value calculated from the following equation is rounded off (N · mm).
Stiffness (N · mm) = Young's modulus (N / mm ² ) × (film thickness (mm)) ³
(4) Using a bending stiffness loop stiffness tester (manufactured by Toyo Seiki Co., Ltd.), a rectangular sample having a length of 5 mm in the width direction and a length of 100 mm in the longitudinal direction is an annular ring, and the displacement speed is about 3.5 mm / The load required to give a displacement of 10 mm in seconds was measured, and the obtained value was taken as the flexural rigidity in the longitudinal direction (N / 5 mm). Similarly, a rectangular sample having a length in the longitudinal direction of 5 mm and a length in the width direction of 100 mm was similarly measured, and the obtained value was defined as the flexural rigidity in the width direction (N / 5 mm). . The flexural rigidity in the longitudinal direction and the flexural rigidity in the width direction were measured five times each, and the value obtained by rounding off the fourth decimal place of the average value of all these values was taken as the flexural rigidity (N / 5 mm).

(5) Elongation at break: A film was cut out as a sample of a 150 mm × 10 mm rectangle having a long side in the longitudinal direction and a 150 mm × 10 mm rectangle having a long side in the width direction. About the obtained sample, crosshead speed 300 mm / min, width 10 mm, test length (distance between chucks) 50 mm using a tensile tester (Tensilon UCT-100 manufactured by Orientec Co., Ltd.) under conditions of 25 ° C. and 63% Rh. As a tensile test, the elongation at the time of breakage of the film was calculated as the elongation at break. The measurement was performed five times in each of the film longitudinal direction and the film width direction. The average value in each direction was taken as the breaking elongation in the film longitudinal direction and the breaking elongation in the film width direction, respectively. A value obtained by rounding off the first decimal place of the average value of the breaking elongation in the film longitudinal direction and the breaking elongation in the film width direction was taken as the breaking elongation (%).

(6) Plane Orientation Coefficient Regarding a biaxially oriented polyester film (A layer), using a sodium D line (wavelength: 589 nm) as a light source, using an Abbe refractometer (model number NAR-1T manufactured by Atago Co., Ltd.) The refractive index (n _MD ), the refractive index in the width direction (n _TD ), and the refractive index in the thickness direction (n _ZD ) were measured, and the plane orientation coefficient (fn) was calculated from the following equation. In addition, the measurement was implemented 5 times and the value which rounded off the 4th decimal place of the average value was made into the surface orientation coefficient.
fn = ( _nMD + _nTD ) / 2- _nZD .

(7) Using a contact angle meter (CA-D manufactured by Kyowa Interface Chemicals Co., Ltd.) for a biaxially oriented polyester film (A layer) conditioned for 24 hours under the conditions of surface free energy 23 ° C. and 65% RH The static contact angles of four kinds of liquids of water, ethylene glycol, formamide and methylene iodide to the surface of the biaxially oriented polyester film (layer A) were determined. Each component of the contact angle obtained for each liquid and the surface tension of the measurement liquid was substituted into the following equation to calculate γ ^L , γ ⁺ , and γ ⁻ .

(γ ^L γ _j ^L ) ^1/2 + 2 (γ ⁺ γ _j ⁻ ) ^1/2 + 2 (γ _j ⁺ γ ⁻ ) ^1/2 = (1 + cos θ) [γ _j ^L + 2 (γ _j ⁺ γ _j ⁻ ) ^{1 / 2} ] / 2
Where γ = γ ^L +2 (γ ⁺ γ ⁻ ) ^1/2 γ _j = γ _j ^L +2 (γ _j ⁺ γ _j ⁻ ) ^1/2
Here, γ, γ ^L , γ ⁺ , and γ ⁻ respectively represent the surface free energy of the film surface, the long distance force term, the Lewis acid parameter, and the Lewis base parameter, γ _j , γ _j ^L , γ _j ⁺ , γ _j ^- represents the surface free energy, long distance force term, Lewis acid parameter, and Lewis base parameter of the measurement solution used, respectively.

  The surface tension of each liquid used here is the value of Table 1 proposed by Oss (“Fundamentals of Adhesion”, L. H. Lee (Ed.), P 153, Plenum ess, New York (1991)). It was.

(8) Film haze The haze was measured using a haze meter (HGM-2GP manufactured by Suga Test Instruments Co., Ltd.) based on JIS K 7105 (1985). The measurement was performed at any three places, and the value obtained by rounding off the second decimal place of the average value was taken as the film haze (%). In addition, it measured similarly about the film haze of each layer.

(9) Peeling strength An acrylic adhesive layer (20 μm) is laminated on a surface protection film obtained by the method described later, and a biaxially oriented polyester film (Toray "Lumirror" (registered trademark) T60: 50 μm is further formed thereon. ) Were laminated to obtain a construction of a film for surface protection / adhesive layer / biaxially oriented polyester film. The structure was cut into a rectangle of 25 mm in width and 150 mm in length and used as a sample. The sample is forcibly peeled between an adhesive layer / biaxially oriented polyester film, and an initial tensile chuck distance 100 mm, using a tensile tester ("TENSILON" (registered trademark) UCT-100 manufactured by Orientec). A 180 ° peel test was conducted at a tensile speed of 20 mm / min. The load was measured at intervals of 0.1 mm until the peeling length reached 130 mm (distance between chucks 230 mm), and the average value of the loads at peeling lengths 25 mm to 125 mm was calculated. In addition, the measurement is performed 5 times, the average value of the average value of the load in peeling length 25 mm-125 mm obtained by each measurement is calculated, and the value which rounded off the decimal place 3rd place is peeling strength (N / 25 mm) And

(10) 10 mm each of both ends in the lengthwise direction of the structure (width 25 mm, length 150 mm rectangle) obtained in the supportability (9) is a cube metal fixing plate having a length of 100 mm on each side It fixed with a tape, the slack condition of the film was confirmed, and the supportability was evaluated by the following reference | standard. In addition, the supportability made A, B, and C the pass level.
A: The central sag in the lengthwise direction was less than 5 mm from the height of the metal fixing plate, showing very good support.
B: The center part sag in the length direction was 5 mm or more and less than 10 mm from the height of the metal fixing plate, showing a good supporting property.
C: The sag in the central portion in the length direction was 10 mm or more and less than 15 mm, and the supportability was at a level that causes no problem in practical use.
D: The supportability was insufficient when the center sag of the longitudinal direction was 15 mm or more.

(11) Peelability (9) With respect to the structure obtained (width 25 mm, length 150 mm rectangle), a trigger for peeling is forcibly formed with the finger from the end, and based on the easiness of the formation. The peelability was evaluated based on the following criteria. In addition, releasability made A, B, and C the pass level.
A: A trigger for peeling was easily formed, and the handleability was very good.
B: Although the cause of peeling was somewhat difficult to form, the handleability was good.
C: Although a trigger for peeling was difficult to form, it was at a level having no problem in practical use.
D: A trigger for peeling was difficult to form, and the handling was poor.

  The following materials were used as a material for forming a layer (A layer) containing a polyester resin as a main component and a layer (B layer) containing a polyolefin resin as a main component.

(1) A layer biaxially oriented polyester film (A-1)
(Thickness: 17 μm, Plane orientation coefficient: 0.162, Film haze: 0.8%)
Biaxially Oriented Polyester Film (A-2)
(Thickness: 25 μm, Plane orientation coefficient: 0.168, Film haze: 1.0%)
Biaxially Oriented Polyester Film (A-3)
(Thickness: 25 μm, Plane orientation coefficient: 0.170, Film haze: 3.0%)
Biaxially Oriented Polyester Film (A-4)
(Thickness: 38 μm, Plane orientation coefficient: 0.165, Film haze: 1.2%)
Biaxially Oriented Polyester Film (A-5)
(Thickness: 25 μm, Plane orientation coefficient: 0.120, Film haze: 1.0%)
In addition, the thickness said here says the thickness measured by the method described in "the thickness of (1) film."

(2) Raw material ethylene-methacrylic acid copolymer for B layer formation "Aklift" (registered trademark) WD301-F (B-1) manufactured by Sumitomo Chemical Co., Ltd.
Ethylene-Hexene Copolymer Prime Polymer "Evolue" (registered trademark) SP2540 (B-2)
Low density polyethylene Sumitomo Chemical "Sumikasen" (registered trademark) L 705 (B-3)
Modified polyethylene Mitsubishi Chemical "Modic" (registered trademark) M504 (B-4)
Example 1
The surface of the biaxially oriented polyester film (A-1) was irradiated with ultraviolet light with an excimer laser (integrated light quantity: 1535 mJ / cm ² ) to make the surface free energy of the film 64 mN / m, and then ethylene was applied to the film surface. Discharging a polyolefin resin in which a methacrylic acid copolymer (B-1) and a modified polyethylene (B-4) are mixed in a mass ratio of 90:10 at a resin temperature of 300 ° C. into a sheet having a thickness of 35 μm from a T-die did. At that time, the biaxially oriented polyester film (A-1) similarly surface-treated is laminated in a configuration in which the layer consisting of B-1 and B-4 is sandwiched, and A layer / B layer / A layer ((A -1) / (B-1): (B-4) = 90: 10 / (A-1)), and press-bonded (nip pressure: 0.2 MPa) with a nip roll and a metal roll cooled to 20 ° C. Thereafter, it was cooled and solidified by a cooling roll (20 ° C.) to obtain a surface protection film having a film thickness of 69 μm. Physical properties and evaluation results of the obtained film are shown in Table 2.

(Example 2)
A film for surface protection having a film thickness of 75 μm was obtained in the same manner as in Example 1 except that the A layer was changed to a biaxially oriented polyester film (A-2) and the B layer thickness was changed to 25 μm. Physical properties and evaluation results of the obtained film are shown in Table 2.

(Example 3)
A film for surface protection having a film thickness of 85 μm was obtained in the same manner as in Example 2 except that the thickness of the layer B was 35 μm. Physical properties and evaluation results of the obtained film are shown in Table 2.

(Example 4)
The layer A was changed to a biaxially oriented polyester film (A-3), and an ethylene-hexene copolymer (B-2) and a modified polyethylene (B-4) were mixed in a mass ratio of 90:10 as the layer B. A film for surface protection having a film thickness of 85 μm was obtained in the same manner as in Example 3 except for the above. Physical properties and evaluation results of the obtained film are shown in Table 2.

(Example 5)
A film thickness of 85 μm was obtained in the same manner as in Example 4 except that a polyolefin resin in which low density polyethylene (B-3) and modified polyethylene (B-4) were mixed in a mass ratio of 90:10 was used as layer B. A film for surface protection was obtained. Physical properties and evaluation results of the obtained film are shown in Table 2.

(Example 6)
A film for surface protection having a film thickness of 96 μm was obtained in the same manner as in Example 1 except that the A layer was changed to a biaxially oriented polyester film (A-4) and the B layer thickness was changed to 20 μm. Physical properties and evaluation results of the obtained film are shown in Table 3.

(Example 7)
A film for surface protection having a thickness of 90 μm was obtained in the same manner as in Example 2 except that the thickness of the layer B was 40 μm. Physical properties and evaluation results of the obtained film are shown in Table 3.

(Example 8)
Urethane-based adhesive + cross-linking agent (made by Toyo Morton "Ad Coat" (registered trademark) AD 502 + Sanwa Chemical manufactured "Nikalac" (registered trademark) MW-22: 75% by mass) on the surface of the biaxially oriented polyester film (A-2) After coating + 25% by mass) at a thickness of 0.01 μm, the ethylene-methacrylic acid copolymer (B-1) and the modified polyethylene (B-4) were mixed on the film surface in a mass ratio of 90:10. The polyolefin resin was discharged in a sheet form of 35 μm from a T-die at a resin temperature of 300 ° C. At that time, a biaxially oriented polyester film (A-2) coated with an adhesive in the same manner is laminated in a configuration in which a polyolefin resin layer is sandwiched, and A layer / B layer / A layer ((A-2) / (B-1): (B-4) = 90: 10 / (A-2)), and press-fit (nip pressure: 0.2 MPa) with a nip roll and a metal roll cooled to 20 ° C., then cooling The film was cooled and solidified on a roll (20 ° C.) to obtain a surface protection film having a film thickness of 85 μm. Physical properties and evaluation results of the obtained film are shown in Table 3.

(Example 9)
A film for surface protection having a film thickness of 85 μm was obtained in the same manner as in Example 2 except that a biaxially oriented polyester film (A-2) was used as the layer A without performing surface treatment. Physical properties and evaluation results of the obtained film are shown in Table 3.

(Example 10)
A film for surface protection having a film thickness of 85 μm was obtained in the same manner as in Example 2 except that ethylene-methacrylic acid copolymer (B-1) was used as layer B. Physical properties and evaluation results of the obtained film are shown in Table 3.

(Comparative example 1)
A film for surface protection having a film thickness of 64 μm was obtained in the same manner as in Example 1 except that the B layer thickness was 30 μm. Physical properties and evaluation results of the obtained film are shown in Table 4.

(Comparative example 2)
A film for surface protection having a film thickness of 101 μm was obtained in the same manner as in Example 1 except that the A layer was changed to a biaxially oriented polyester film (A-4) and the B layer thickness was changed to 25 μm. Physical properties and evaluation results of the obtained film are shown in Table 3.

(Comparative example 3)
A film for surface protection having a film thickness of 75 μm was obtained in the same manner as in Comparative Example 2 except that the layer A was changed to a biaxially oriented polyester film (A-5). Physical properties and evaluation results of the obtained film are shown in Table 3.

  The film for surface protection of the present invention has both supportability and releasability, can be applied to high definition and thin members, and can be preferably used for circuit members, display members, medical members and the like.

Claims (7)

Rigidity obtained by the following formula is at 1.00 N · mm or more, the bending stiffness is determined by loop stiffness test method 0.040N / 5mm Ri der hereinafter, a Young's modulus of 2,000 N / mm ² or more 4,000N / Mm ² or less,
A layer (A layer) containing a polyester resin as a main component and a layer (B layer) containing a polyolefin resin as a main component,
The polyester resin is polyethylene terephthalate,
The layer A contains 80% by mass or more and 100% by mass or less of the polyester-based resin, assuming that the entire layer is 100% by mass.
The layer B contains 50% by mass or more of a polyethylene-based resin as the polyolefin-based resin when all the components in the layer B are 100% by mass, and contains an acid-modified polyethylene-based resin. , Film for surface protection.
Stiffness (N · mm) = Young's modulus (N / mm ² ) × (film thickness (mm)) ³ The film for surface protection according to claim 1 , wherein the elongation at break of the film at 25 ° C is 50% or more. Characterized in that the film haze of 5.0% or less, a surface protective film according to claim 1 or 2. The film for surface protection according to any one of claims 1 to 3 , wherein the layer A / layer B / layer A is directly laminated in this order. The structure formed by laminating | stacking the film for surface protections in any one of Claims 1-4 on the at least single side | surface of a to-be-adhered body. The structure according to claim 5 , wherein the adherend and the film for surface protection are laminated via an adhesive layer. The peeling strength of the said to-be-adhered body and the said film for surface protections is 0.01 N / 25 mm or more and 5.00 N / 25 mm or less, The structure of Claim 5 or 6 characterized by the above-mentioned.