Laminated film

Abstract

To provide a laminated film which is excellent in uniform stretchability at the time of lens bonding while excellent in cutting property.SOLUTION: A laminated film has a resin layer A and a base material layer, and satisfies the following (a) and (b). (a) Maximum tensile elastic modulus at 20-100% elongation in an extrusion direction (MD) of 1.0-20 MPa, and (b) tear strength in the extrusion direction (MD) of 4.9-49 N / mm.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to a laminated film. [Background technology]

[0002] Optical products made from various materials such as synthetic resins, metals, and glass are susceptible to scratches and dirt that occur during processing, transportation, and storage. Therefore, it is common practice to handle them with protective sheets or films laminated to the surface. Generally, surface protective films with an adhesive layer formed on a support base made of thermoplastic resin or paper are used, and the adhesive layer surface is laminated to the object to be attached.

[0003] Examples of such surface protective films include those described in Patent Documents 1 to 3. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 04-146983 [Patent Document 2] Special Publication No. 11-512478 [Patent Document 3] Japanese Patent Publication No. 2011-037243 [Overview of the project] [Problems that the invention aims to solve]

[0005] The properties required for such surface protection films include the ability to adhere to substrates with various surface shapes as well as smooth surfaces; resistance to peeling from the substrate due to environmental changes such as temperature and humidity or minor stress; ease of removal from the substrate after processing or use; and the absence of adhesive residue on the substrate after removal.

[0006] Products requiring surface protection films include, for example, display components, automotive components, building materials, and lenses for optical instruments and eyeglasses. Among these, lenses for optical instruments and eyeglasses have curved shapes, and therefore require strong adhesive force to protect the surface along that shape. However, achieving both strong adhesive force and ease of removal after use, as well as non-contamination of the adherend, has been extremely difficult.

[0007] Furthermore, in eyeglass lenses, polishing is performed during the surface finishing process. During this polishing, a block of molten low-melting-point alloy is cast onto the back of the lens polishing surface, integrating it with the lens. This low-melting-point alloy is then mounted on a fixed shaft and rotated for polishing. In this process, a surface protection film is used on the back surface to protect the lens surface while ensuring adhesion with the low-melting-point alloy. To improve adhesion with the low-melting-point alloy in this surface protection film, it is common to improve the polarity of the contact surface with the low-melting-point alloy. However, it has been found that when conventional surface protection films are wound into a roll without a release liner, the adhesive surface and the contact surface with the low-melting-point alloy stick together strongly, making unwinding difficult.

[0008] Furthermore, when laminating the film to the lens, the film stretches during the lamination process, and then the stretched film is cut along the lens. However, with conventional surface protection films, lamination to the lens does not result in uniform stretching, leading to localized stretching and tearing, which makes it difficult to cut the film along the lens.

[0009] Furthermore, even if a film can be uniformly stretched, if it is difficult to cut, film scraps are generated, worsening work efficiency. Therefore, there is a challenge in achieving easy cutting properties. For this reason, there is a need for a surface protection film that can be uniformly stretched and has excellent cutability.

[0010] The film described in Patent Document 1 has sufficient adhesion to low-melting-point alloys, but requires a release liner to be wound in a roll, resulting in a high environmental impact. Furthermore, when used for eyeglass lenses, it has problems such as poor cutting. The film described in Patent Document 2 has sufficient adhesion to low-melting-point alloys, but lacks sufficient adhesive strength. When used for eyeglass lenses, it cannot conform to the curved surface of the lens, causing lifting at the edges and making it difficult to cut. The film described in Patent Document 3 has excellent roll unwinding properties, but has low adhesive strength. When used for eyeglass lenses, the film stretches locally during lamination to the lens, making it difficult to cut.

[0011] Thus, the films described in Patent Documents 1 to 3 failed to provide a film that achieved both uniform stretchability and cutability during lens lamination.

[0012] Therefore, the object of the present invention is to provide a laminated film that maintains adhesiveness, has excellent cutability, and exhibits excellent uniform stretchability when bonding lenses. [Means for solving the problem]

[0013] One preferred embodiment of the laminated film of the present invention is as follows. (1) A laminated film having an adhesive resin layer A and a base layer, wherein the laminated film satisfies the following (a) and (b). (a) Maximum tensile modulus of elasticity at 20% to 100% elongation in the extrusion direction (MD) is 1.0 to 20 MPa (b) Tear strength in the extrusion direction (MD) of 4.9 to 49 N / mm (2) The laminated film described in (1), wherein the stress ratio (stress in MD / stress in TD) between the extrusion direction (MD) and the width direction (TD) when stretched to 100% is 1.0 to 2.0. (3) The laminated film according to (1) or (2), wherein the water contact angle of the surface opposite to the surface on the side of resin layer A is 90° or more and 110° or less. (4) The maximum polycarbonate probe tack F on the surface of resin layer A is 0.098~0.245 N / mm 2The laminated film according to any one of (1) to (3). (5) The laminated film according to any one of (1) to (4), wherein after laminating the surface on the resin layer A side and the surface on the side opposite to the surface on the resin layer A side at a pressure of 0.1 MPa and storing for 24 hours, the 180° peel strength is 5.88 N / 25 mm or less. (6) The laminated film according to any one of (1) to (5), wherein the base material layer contains a coloring agent. [[Effect of the Invention]]

[0014] According to the present invention, there is provided a laminated film that maintains adhesiveness, is excellent in cutting properties, and is excellent in uniform stretchability during lens lamination. [[Embodiment for Carrying out the Invention]]

[0015] Hereinafter, embodiments of the present invention will be described.

[0016] A preferred aspect of the present invention is a laminated film having a resin layer A having adhesiveness and a base material layer, and satisfying the following (a) and (b). (a) The maximum tensile elastic modulus at 20% to 100% elongation in the extrusion direction (MD) is 1.0 to 20 MPa (b) The tear strength in the extrusion direction (MD) is 4.9 to 49 N / mm.

[0017] By adopting the above aspect, it is possible to provide a laminated film that maintains adhesiveness, is excellent in cutting properties, and is excellent in uniform stretchability during lens lamination.

[0018] Here, the resin layer A preferably has adhesiveness. Preferred aspects of the resin layer A will be described later. In the present invention, the surface on the resin layer A side of the laminated film refers to the surface on the air side when the laminated film is viewed in the order of air, resin layer A, and base material layer when the laminated film is placed in the air.

[0019] From the viewpoint of cutting the laminated film after bonding it to the adherend, it is preferable that the base layer contains an olefin resin. However, there is a problem in that the film cannot be uniformly stretched when bonding it to the adherend, making it difficult to cut. In order to achieve both cutability and uniform stretchability of the laminated film, the inventors diligently studied and found that by setting the maximum tensile modulus and tear strength of the laminated film at 20% to 100% elongation to a preferred range, it is possible to obtain a laminated film that maintains adhesiveness, has excellent cutability, and has excellent uniform stretchability when bonding lenses, leading to the present invention. The details will be explained below.

[0020] The laminated film of the present invention preferably has a maximum tensile modulus of 1.0 to 20 MPa when tensile at 20% to 100% in the extrusion direction (MD) at a tensile speed of 300 mm / min. The tensile modulus can be calculated by performing a tensile test in the extrusion direction (MD direction) of the laminated film using the method described in the examples. If the MD direction of the laminated film is unknown, the tensile modulus can be calculated using the following method. First, tensile tests are performed five times each in four directions at 45° intervals, starting from any direction within the film surface. Then, the arithmetic mean of each direction is calculated, and the arithmetic mean of the direction with the highest tensile modulus is taken as the tensile modulus of the laminated film of the present invention.

[0021] By setting the maximum tensile modulus at 20% to 100% tension in the extrusion direction (MD) at a tensile speed of 300 mm / min to 1.0 MPa or higher, the laminated film can be stretched uniformly without localized stretching when bonded to an adherend, and film breakage during peeling can be suppressed. From a similar viewpoint, the maximum tensile modulus at 20% to 100% tension in the extrusion direction (MD) at a tensile speed of 300 mm / min is more preferably 5 MPa or higher. Furthermore, if the maximum tensile modulus at 20% to 100% tension in the extrusion direction (MD) at a tensile speed of 300 mm / min exceeds 20 MPa, the stress ratio between the extrusion direction (MD) and the width direction (TD) of the laminated film becomes large, and in the case of circular adherends such as eyeglass lenses, the laminated film cannot be stretched uniformly, resulting in localized stretching and making it difficult to cut. Therefore, it is preferable that the maximum tensile modulus at 20% to 100% tension is 20 MPa or lower. From a similar viewpoint, the maximum tensile modulus of the laminated film of the present invention when tensile at 20% to 100% in the extrusion direction (MD) at 300 mm / min is more preferably 10 MPa or less.

[0022] The tensile modulus of the laminated film of the present invention can be adjusted by adjusting the material and thickness of the base layer and resin layer A, as described later, but it can be achieved in particular by controlling the rigidity of the base layer based on the raw material composition and film formation conditions described later. Specifically, as a method to make the maximum tensile modulus of elasticity 1.0 to 20 MPa at 20% to 100% tension in the extrusion direction (MD) at 300 mm / min, for example, the density of the base layer is 910 to 940 kg / m³ 3 A preferred method is one that primarily contains polyethylene resin such as low-density polyethylene, medium-density polyethylene, or linear low-density polyethylene.

[0023] The laminated film of the present invention preferably has a tear strength of 4.9 to 49 N / mm in the extrusion direction (MD direction). The tear strength can be measured and calculated by the method described in the examples. If the extrusion direction (MD direction) of the laminated film is unknown, the tear strength can be calculated by the following method. First, the tear strength is evaluated five times each in four directions at 45° intervals, starting from any direction within the film surface. Then, the arithmetic mean of each direction is calculated, and the arithmetic mean of the direction with the highest tear strength and the direction at 90° to this direction (average of a total of 10 measurements) is taken as the tear strength of the laminated film of the present invention in the extrusion direction (MD direction). By setting the tear strength in the extrusion direction (MD direction) to 4.9 N / mm or higher, film breakage when peeling the film from the adherend can be suppressed. From a similar viewpoint, the tear strength in the extrusion direction (MD direction) is more preferably 9.8 N / mm or higher, and even more preferably 19.6 N / mm or higher. Furthermore, by setting the tear strength in the extrusion direction (MD direction) to 49 N / mm or less, the cutability of the laminated film when it is bonded to a curved surface such as a lens can be improved. From a similar viewpoint, a tear strength in the extrusion direction (MD direction) of 34.3 N / mm or less is more preferable.

[0024] The tear strength can be controlled by adjusting the materials, thickness, and film formation conditions of the resin layer A, the base layer, or the layer having a surface opposite to the surface of resin layer A. In particular, it can be achieved by controlling the rigidity of the base layer based on the raw material composition of the base layer, as described later. A preferred method for achieving a tear strength of 4.9 N to 49 N / mm in the extrusion direction (MD direction) is the same as the method for achieving a maximum tensile modulus of elasticity of 1.0 to 20 MPa at 20% to 100% tension in the extrusion direction (MD).

[0025] The laminated film of the present invention preferably has an extrusion direction (MD) to width direction (TD) stress ratio (MD stress / TD stress) of 1.0 to 2.0 when subjected to 100% tension at a tensile speed of 300 mm / min. The MD / TD stress ratio can be calculated by performing a tensile test on the laminated film using the method described in the examples. If the MD direction of the laminated film is unknown, the MD / TD stress ratio can be calculated using the following method. First, tensile tests are performed five times each in four directions at 45° intervals, starting from an arbitrary direction within the film surface. Then, the tensile stress in each direction is determined, and the direction with the highest tensile stress is taken as the MD tensile stress, and the tensile stress in the direction 90° to that direction is taken as the TD tensile stress. By setting the extrusion direction (MD) to width direction (TD) stress ratio (MD stress / TD stress) to 1.0 or higher when subjected to 100% tension at a tensile speed of 300 mm / min, circular adherends such as eyeglass lenses can be stretched more uniformly during lamination. Furthermore, from a similar viewpoint, it is preferable that the stress ratio (MD stress / TD stress) between the extrusion direction (MD) and the width direction (TD) at 100% tensile strength is 2.0 or less, from the viewpoint of uniform stretchability.

[0026] In order to achieve sufficient adhesion between the surface opposite to the resin layer A side and the low-melting-point alloy, it is preferable that the water contact angle of the laminated film of the present invention be 90° or more and 110° or less.

[0027] The water contact angle was measured by the method described in the examples. By setting the water contact angle to 110° or less, the problem of the low-melting-point alloy block peeling off when the laminated film of the present invention is bonded to a curved substrate, a low-melting-point alloy is cast onto the surface opposite to the surface on which resin layer A is located, and then integrated with the lens, and the lens is polished by pressing this block-shaped low-melting-point alloy against a rotating polishing surface attached to a fixed shaft can be further resolved. From a similar viewpoint, the water contact angle of the surface opposite to the surface on which resin layer A is located is preferably 105° or less, and more preferably 100° or less. Furthermore, by setting the water contact angle to 90° or more, the low-melting-point alloy cast onto the laminated film can be easily peeled off after lens polishing.

[0028] The adhesion force with the low-melting-point alloy can be controlled by the layer including the surface opposite to the surface on the side of resin layer A, the materials of the base layer and resin layer A, and the film formation conditions, as described later. In particular, this can be achieved by controlling the adhesive properties of resin layer A, the rigidity of the base layer, and the surface properties of the layer including the surface opposite to the surface on the side of resin layer A, based on the raw material composition described later. A specific method for setting the water contact angle of the surface opposite to the surface on the side of resin layer A to 90-110° is, for example, a method in which 80% by mass or more of ethylene-acrylic acid copolymer and / or ethylene-methacrylic acid copolymer are contained in 100% by mass of the layer including the surface opposite to the surface on the side of resin layer A.

[0029] The laminated film of the present invention has a maximum polycarbonate probe tack value F of 0.098 to 0.245 N / mm² on the surface of resin layer A. 2 It is preferable that this is the case. The maximum polycarbonate probe tack value F is measured by the method described in the examples. The maximum polycarbonate probe tack value F is an index of the tackiness of the surface on the resin layer A side, evaluated with a polycarbonate probe. Furthermore, if the surface on the resin layer A side of the laminated film and the surface opposite to the resin layer A side are unknown, the surfaces can be identified by the following method. First, the maximum polycarbonate probe tack value F of both sides of the laminated film is measured according to the method described in the examples. Then, the surface with a large arithmetic mean of the maximum polycarbonate probe tack value F in the laminated film is designated as the surface on the resin layer A side, and the surface with a small value is designated as the surface opposite to the resin layer A side.

[0030] The maximum polycarbonate probe tack F on the surface of resin layer A was 0.098 N / mm². 2As a result, the film exhibits greater adhesiveness, and when the laminated film of the present invention is bonded to a curved substrate, it is possible to suppress the film from lifting away from the substrate due to its inability to conform to the curved surface. Furthermore, because it has sufficient adhesive strength, when used as a protective film for eyeglass lenses, for example, it is possible to suppress the film from peeling off the lens during polishing. In addition, when peeled off from the substrate, the adhesive component is less likely to remain on the substrate. From a similar viewpoint, the maximum polycarbonate probe tack value F is more preferably 0.147 N / mm². 2 The above is preferable, and more preferably 0.196 N / mm 2 That's all.

[0031] Furthermore, the maximum tack value F of the polycarbonate probe is 0.245 N / mm². 2 The following conditions ensure that the layer containing the surface opposite to the surface on the resin layer A side contains a polyolefin resin containing a carboxylic acid group, and / or a polyolefin resin containing a carboxylic acid metal base, and even when wound into a roll without a release liner, it can be easily unwound without blocking, thus not impairing workability.

[0032] The maximum polycarbonate probe tack value F can be achieved by controlling the surface condition based on the raw material composition and film formation conditions described later. Specifically, the maximum polycarbonate probe tack value F on the resin layer A side surface is set to 0.098~0.245 N / mm². 2 As an example of such a method, a preferred method is to include a total of 60 to 90% by mass of a styrene-based elastomer having a storage modulus of 0.1 to 0.9 MPa at 25°C and 1 Hz in 100% by mass of resin layer A, and a total of 10 to 40% by mass of a terpene-based resin as a tackifier in resin layer A.

[0033] By setting the viscoelasticity and content of the styrene-based elastomer contained in resin layer A within the above range, the laminated film of the present invention exhibits good adhesion when bonded to an adherend, and good adhesive properties such as suppression of adhesive residue can be achieved. Furthermore, by including a terpene-based resin in resin layer A and setting its content within the above range, good adhesion to adherends with curved shapes can be obtained. In addition, adhesive residue is less likely to occur when peeling the film off after bonding to an adherend.

[0034] The laminated film of the present invention preferably has a 180° peel strength (hereinafter referred to as peel strength) of 5.88 N / 25 mm or less, more preferably 4.9 N / 25 mm or less, and even more preferably 2.94 N / 25 mm or less, after being stored for 24 hours following lamination of the surface on the side of resin layer A of the laminated film with the surface opposite to the surface on the side of resin layer A at 0.1 MPa. From the viewpoint of ease of handling, a lower peel strength is preferable, and no lower limit is set in particular, but considering that it is preferable for the surface on the side with resin layer A to be adhesive, the practical lower limit is about 0.49 N / 25 mm. When the peel strength is within the above preferred range, the laminated film of the present invention can be easily unwound when used, even when wound into a roll without using a release liner. The peel strength was measured by the method described in the examples.

[0035] Furthermore, the peeling force can be controlled to the preferred range by adjusting the material and surface roughness of the layer including the surface opposite to the surface on the side of resin layer A, as well as the rigidity of the base layer. Specifically, for example, it is preferable to set the ten-point average roughness Rz of the surface opposite to the surface on the side of resin layer A to 5 μm or more, and to include a 4-methyl-1-pentene·α-olefin copolymer in the layer including the surface opposite to the surface on the side of resin layer A.

[0036] Furthermore, the thickness of the laminated film of the present invention is preferably 15 μm or more, and more preferably 30 μm or more, from the viewpoint of transportability and productivity during manufacturing and use. In addition, the thickness of the laminated film is preferably 250 μm or less, in addition to the same viewpoint as above, from the viewpoint of conformability to the adherend.

[0037] Preferably, the film roll obtained by winding the laminated film of the present invention into a roll shape is a film roll in which the surface of the laminated film having the resin layer A is in contact with the surface of the opposite layer. By adopting such a configuration that does not use a release liner, the process of peeling off the release liner during use can be eliminated, further reducing the amount of waste, and because there is no release liner, the usable surface area of ​​the protective film per roll increases, and effects such as reducing the number of times the roll product needs to be replaced can be expected.

[0038] (Resin layer A) The resin layer A in the present invention is not particularly limited as long as it does not impair the effects of the present invention, and may include elastomers such as acrylic, silicone, natural rubber, and synthetic rubber. However, it is preferable that the components after drying the insoluble matter (tetrahydrofuran insoluble matter) obtained by extracting the resin layer A with tetrahydrofuran contain at least a styrene component as a monomer component, and that the storage modulus G'(25) of the components after drying the insoluble matter at 25°C and 1 Hz is 0.05 to 0.9 MPa, and that the content of the insoluble matter in 100% by mass of the resin layer A is 40 to 90% by mass.

[0039] Furthermore, when resin layer A in the present invention is extracted with tetrahydrofuran, an excess amount of acetone is added to the dissolved substance, and the resulting insoluble matter (acetone-insoluble matter) and acetone-soluble matter are centrifuged using a centrifuge. The components after drying the separated acetone-soluble matter preferably contain a terpene resin, and when resin layer A is considered as 100% by mass, the content of the components after drying the acetone-soluble matter is preferably 10 to 40% by mass. In particular, it is more preferable that 100% by mass of resin layer A contains 40 to 90% by mass of styrene elastomer and 10 to 40% by mass of terpene resin, and it is even more preferable that the storage modulus G'(25) of the styrene elastomer at 25°C and 1 Hz is 0.05 to 0.9 MPa. The tetrahydrofuran-insoluble matter, acetone-soluble matter, and methods for extracting and analyzing the acetone-insoluble matter can be carried out by the following methods.

[0040] First, place the surface of the resin layer A side of the laminated film facing up, and bring the surface opposite to the surface of the resin layer A side into close contact with the inside of the vat. Pour tetrahydrofuran onto the resin layer A surface, immerse it at a liquid temperature of 25°C for 10 minutes, and then recover the solution, which is used as a single-sided extract (extraction area: 15 cm × 20 cm of the laminated film, 2 sheets). Then, separate it into tetrahydrofuran-insoluble matter and tetrahydrofuran-soluble matter by centrifugation. Next, add acetone to the tetrahydrofuran-soluble matter at a ratio of 50 L of acetone to 1 L of tetrahydrofuran, and separate it into acetone-insoluble matter and acetone-soluble matter by centrifugation. The tetrahydrofuran-insoluble matter, acetone-soluble matter, and acetone-insoluble matter are dried, and after determining their masses, the mass percentages of each sample are calculated when the mass of the resin layer A is 100 mass%. Among these, for each of the tetrahydrofuran-insoluble matter and acetone-insoluble matter 1 Perform 1H-NMR, identify the peaks, and confirm the presence or absence of the styrene component. Also, in the peak area ratio of each of the tetrahydrofuran-insoluble matter and acetone-insoluble matter, after calculating the amount of the styrene component-containing substance, multiply the mass percentage of the tetrahydrofuran-insoluble matter and the mass percentage of the acetone-insoluble matter respectively, and sum them to obtain the content of the styrene-based elastomer in 100 mass% of the resin layer A.

[0041] Next, the tetrahydrofuran-insoluble material is dried and then melt-molded to a thickness of 1 mm to obtain the sample. The measurement is performed using a TA Instruments AR2000ex rheometer. The sample is cooled from 200°C to -20°C at a rate of 20°C / min, and then heated from -20°C to 40°C at a rate of 10°C / min while undergoing dynamic shear deformation at a frequency of 1 Hz and a strain of 0.01%. The storage modulus at 25°C during the heating process of the tetrahydrofuran-insoluble sample is evaluated. If the storage modulus obtained when a dried tetrahydrofuran-insoluble material and a dried acetone-insoluble material are melt-mixed and melt-molded and measured in the same manner as described above is 0.05 to 0.9 MPa, or if the storage modulus G'(25) of the styrene-based elastomer determined from the raw materials at 25°C and 1 Hz is 0.05 to 0.9 MPa, then the storage modulus G'(25) of the styrene-based elastomer at 25°C and 1 Hz is 0.05 to 0.9 MPa.

[0042] As for the dried acetone-soluble substance mentioned above, 1 ¹H-NMR is performed, and the ratio of terpene resins is determined from the peak area ratio. This ratio is then multiplied by the mass percentage of acetone-soluble substances to obtain the terpene resin content in resin layer A.

[0043] By adopting the above configuration, the laminated film can have sufficient tackiness while minimizing adhesive residue, and the surface opposite to the surface of resin layer A can be configured in the preferred manner described above, while also reducing blocking when wound onto a roll without using a release liner. Specifically, the storage modulus G'(25) at 25°C and 1Hz of the component after drying the insoluble matter when resin layer A is extracted with tetrahydrofuran is 0.05 to 0.9 MPa, so that some tackiness can be obtained from the component itself, and since this component is a component with low adhesive residue, when included together with a terpene resin, it can have sufficient tackiness, and even when the laminated film of the present invention is wound without using a release liner, it can be easily unwound at the time of use. Furthermore, by including a terpene resin that does not have excessively high tack-imparting properties, it is possible to have sufficient tackiness while minimizing adhesive residue when the laminated film is peeled from the adherend.

[0044] As a method for achieving the above embodiment, a method is preferred in which 40 to 90% by mass of styrene-based elastomer and 10 to 40% by mass of terpene-based resin are contained in 100% by mass of resin layer A. The styrene-based elastomer refers to a resin having a storage modulus G'(25) of 10 MPa or less at 25°C and 1 Hz, and containing at least a styrene component as a monomer component. As the styrene-based elastomer, for example, styrene-conjugated diene copolymers such as styrene-butadiene copolymer (SBR), styrene-isoprene-styrene copolymer (SIS), and styrene-butadiene-styrene copolymer (SBS), or their hydrogenated products can be used. Specifically, for example, hydrogenated styrene-butadiene copolymer (HSBR), styrene-ethylenebutylene-styrene triblock copolymer (SEBS), styrene-ethylenebutylene diblock copolymer (SEB), and styrene-isobutylene copolymers can be suitably used. As the styrene-isobutylene copolymer mentioned above, for example, styrene-isobutylene-styrene triblock copolymer (SIBS), styrene-isobutylene diblock copolymer (SIB), or mixtures thereof can be suitably used. Among these, it is more preferable to use one or more selected from styrene-butadiene-styrene copolymer (SBS), their hydrogenated derivatives, and styrene-isobutylene copolymers, and even more preferable to use styrene-ethylenebutylene-styrene triblock copolymer (SEBS), from the viewpoint of having sufficient tackiness, low adhesive residue, the surface opposite to the surface on the resin layer A side having the preferred configuration described above, and reducing blocking even when wound on a roll without using a release liner. Furthermore, it is preferable to use only one type of styrene elastomer, or to use two or more types in combination.

[0045] Furthermore, when the laminated film of the present invention is bonded to a curved substrate, in order to prevent the laminated film from lifting away from the substrate due to its inability to conform to the curved surface and to adequately protect the substrate, it is preferable that the storage modulus G'(25) of the styrene-based elastomer at 25°C and 1Hz be 0.9 MPa or less, more preferably 0.7 MPa or less, and even more preferably 0.5 MPa or less. In addition, in order to suppress adhesive residue when the laminated film of the present invention is bonded to a substrate and peeled off after use, it is preferable that the storage modulus G'(25) of the styrene-based elastomer be 0.05 MPa or more, and more preferably 0.1 MPa or more.

[0046] The melt flow rate (MFR, measured under the conditions of 230°C and 2.16 kg) of the styrene-based elastomer is preferably 2 g / 10 min or more, more preferably 4 g / 10 min or more, and even more preferably 10 g / 10 min or more. Furthermore, the MFR of the styrene-based elastomer is preferably 60 g / 10 min or less, more preferably 30 g / 10 min or less, and even more preferably 20 g / 10 min or less. By setting the MFR of the styrene-based elastomer within the above range, excellent productivity can be achieved, and the laminated film of the present invention can exhibit good adhesive properties when used as a surface protective film.

[0047] Furthermore, the styrene content in the styrene-based elastomer is preferably 5% by mass or more, and more preferably 8% by mass or more, when the total styrene-based elastomer is considered to be 100% by mass. Also, the styrene content in the styrene-based elastomer is preferably 55% by mass or less, and more preferably 40% by mass or less. By keeping the styrene content in the styrene-based elastomer within the above range, when the laminated film of the present invention is bonded to an adherend, it exhibits good adhesion, suppresses adhesive residue, and demonstrates other good adhesive properties.

[0048] In the present invention, the resin layer A preferably contains a tackifier in order to improve adhesion to the adherend. Known tackifiers can be used, but generally, petroleum resins such as aliphatic copolymers, aromatic copolymers, aliphatic-aromatic copolymers and alicyclic copolymers, terpene resins, rosin resins, alkylphenol resins, xylene resins, or hydrogenated versions thereof can be used. Among these, aliphatic copolymers, aliphatic-aromatic copolymers, terpene resins, and hydrogenated versions thereof are preferably used because they have excellent compatibility with the styrene elastomer and increase the maximum polycarbonate probe tack value F of the laminated film. In particular, terpene resins and hydrogenated versions thereof can be used more preferably from the above viewpoint, and terpene phenol resins can be used even more preferably as terpene resins.

[0049] The tackifier content is preferably 10% by mass or more, and more preferably 15% by mass or more, when the entire resin layer A is considered to be 100% by mass. Furthermore, the tackifier content is preferably 40% by mass or less, and more preferably 30% by mass or less, when the entire resin layer A is considered to be 100% by mass. By setting the tackifier content to 10% by mass or more, the maximum polycarbonate probe tack value F of the laminated film of the present invention can be increased, and good adhesion to substrates having a curved shape can be obtained. Furthermore, by setting the tackifier content to 40% by mass or less, it is possible to reduce the amount of adhesive residue that is left when peeling off after bonding to a substrate.

[0050] The resin layer A in the present invention may contain an olefin resin from the viewpoint of controlling the viscoelasticity of the resin layer and adjusting the adhesive strength, and from the viewpoint of obtaining good film-forming properties. Examples of olefin resins include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, low-crystalline or amorphous ethylene-α-olefin copolymer, crystalline polypropylene, low-crystalline polypropylene, amorphous polypropylene, propylene-ethylene copolymer (random copolymer and / or block copolymer), propylene-α-olefin copolymer, propylene-ethylene-α-olefin copolymer, polybutene, 4-methyl-1-pentene-α-olefin copolymer, ethylene-ethyl (meth)acrylate copolymer, ethylene-methyl (meth)acrylate copolymer, ethylene-n-butyl (meth)acrylate copolymer, and ethylene-vinyl acetate copolymer, which may be used alone or in combination. The α-olefin is not particularly limited as long as it can copolymerize with ethylene or propylene, and preferred examples include ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-pentene, and 1-heptene.

[0051] Among the olefin resins mentioned above, low-density polyethylene, linear low-density polyethylene, ethylene-α-olefin copolymer, propylene-α-olefin copolymer, polybutene, crystalline polypropylene, low-crystalline polypropylene, amorphous polypropylene, or 4-methyl-1-pentene-α-olefin copolymer are preferably used.

[0052] When an olefin-based resin is used in the resin layer A of the present invention, its content is preferably 20% by mass or less, and more preferably 10% by mass or less, when the total mass of resin layer A is 100% by mass.

[0053] In the present invention, the resin layer A may contain other components such as resin components and particles other than the styrene elastomer, tackifier, and olefin resin, fillers, and additives, as appropriate, within limits that do not impair the objectives of the present invention. Examples of such additives include lubricants, nucleating agents, antioxidants, heat-resistant agents, weather-resistant agents, and antistatic agents. These additives may be used individually or in combination, but the total content of these additives is preferably 3% by mass or less, and more preferably 2% by mass or less, when the total mass of the resin layer A is considered to be 100% by mass.

[0054] (base material layer) A preferred embodiment of the laminated film of the present invention has a base layer, where the base layer refers to a sheet-like material having a finite thickness.

[0055] In the present invention, the base layer may be positioned as the outermost layer opposite to the surface on the side of resin layer A and may also be a layer that includes the surface opposite to the surface on the side of resin layer A as described above. However, it is more preferable to have a three-layer structure consisting of resin layer A, the base layer, and the layer opposite to the surface on the side of resin layer A (hereinafter sometimes referred to as resin layer B). In this case, the material of the base layer is not particularly limited, but for example, olefin resins or ester resins can be used, and among these, it is preferable to use an olefin resin as the main component from the viewpoint of productivity and processability. The main component referred to here means the component with the highest mass % among all the components constituting the base layer.

[0056] Examples of the olefin resins included as the main component in the substrate layer include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, low-crystalline or amorphous ethylene-α-olefin copolymers, polypropylene, propylene-α-olefin copolymers, propylene-ethylene-α-olefin copolymers, ethylene-ethyl (meth)acrylate copolymers, ethylene-methyl (meth)acrylate copolymers, ethylene-n-butyl (meth)acrylate copolymers, and ethylene-vinyl acetate copolymers. Among these, ethylene resins such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, low-crystalline or amorphous ethylene-α-olefin copolymers, ethylene-ethyl (meth)acrylate copolymers, ethylene-methyl (meth)acrylate copolymers, ethylene-n-butyl (meth)acrylate copolymers, and ethylene-vinyl acetate copolymers are particularly preferred. These may be used alone or in combination.

[0057] In particular, olefin resins suitable for the laminated film of the present invention have a density of 910 to 940 kg / m³. 3 Methods that primarily contain low-density polyethylene, medium-density polyethylene, linear low-density polyethylene, etc., are preferred. Among these, those with a density of 910-940 kg / m³ are particularly preferred. 3 It is preferable to use low-density polyethylene with a density of 910-940 kg / m³. 3 Furthermore, by using low-density polyethylene with an MFR of 0.2 to 10 g / min, the rigidity of the base layer can be controlled, and the uniform stretchability of the laminated film of the present invention can be achieved.

[0058] Furthermore, from the perspective of controlling tear strength and rigidity, a density of 920-930 kg / m³ is desirable. 3 Furthermore, it is more preferable to use low-density polyethylene with an MFR of 0.4 to 6 g / min. Density of 920 to 940 kg / m³ 3Furthermore, by using low-density polyethylene with an MFR of 0.4 to 6 g / min, the uniform stretchability of the laminated film of the present invention can be further enhanced.

[0059] The base layer in the present invention preferably contains a styrene elastomer. That is, the base layer of the laminated film of the present invention more preferably contains an olefin resin and a styrene elastomer, even more preferably contains the olefin elastomer and an olefin resin excluding the olefin elastomer, and particularly preferably contains the olefin elastomer, an olefin resin excluding the olefin elastomer and a styrene elastomer.

[0060] By including a styrene-based elastomer in the base layer, when a styrene-based elastomer is used in the resin layer A, the affinity between the base layer and the resin layer A is improved, and the interfacial adhesion between the base layer and the resin layer A can be increased. When the entire base layer is considered as 100% by mass, the styrene-based elastomer content in the base layer is preferably 1% by mass or more, and more preferably 2% by mass or more. Furthermore, the styrene-based elastomer content in the base layer is preferably 20% by mass or less, and more preferably 10% by mass or less. In addition, known styrene-based elastomers can be used for the base layer in the present invention, and for example, the same styrene-based elastomer suitable for the resin layer A described above can be used.

[0061] One method for incorporating a styrene-based elastomer into the base layer in the present invention is to add a recovered raw material, which is made by recovering and recycling the laminated film containing the styrene-based elastomer, to the resin layer A and use it in the base layer. This method is preferable from the viewpoint of resin recycling and reduction of production costs.

[0062] Furthermore, various additives such as nucleating agents, lubricants, antioxidants, weathering agents, and antistatic agents may be appropriately added to the substrate layer in the present invention, to the extent that they do not impair the properties of the laminated film of the present invention. In addition, the substrate layer in the present invention may further contain an easy-adhesion component for good lamination with the resin layer A of the present invention.

[0063] The laminated film of the present invention preferably contains a coloring agent in the base layer. When used as a surface protective film, coloring the laminated film is expected to reduce the risk of forgetting to remove it, from the viewpoint of preventing forgetting to remove it. It is preferable to contain the coloring agent in the base layer in order to suppress contamination of the adherend. The coloring agent is not particularly limited, but from the viewpoint of dispersibility in the resin, it is preferable to have a pigment.

[0064] The above-mentioned pigments may be either inorganic or organic pigments. Examples of inorganic pigments include pigments derived from natural earths such as amber, sienna, and calcium carbonate, as well as synthetic inorganic pigments such as Prussian blue, titanium dioxide, zinc oxide, synthetic iron oxide red, cadmium yellow, nickel titanium yellow, strontium yellow, hydrated chromium oxide, chromium oxide, cobalt aluminate, and synthetic ultramarine blue. Carbon flax can also be used. As organic pigments, azo pigments or polycyclic pigments can be used. Examples of azo pigments include monoazo pigments, disazo pigments, condensed disazo pigments, and benzimidazolone pigments. Examples of polycyclic pigments include isoindolinone, isoindoline, azomethine, anthraquinone, anthrone, xanthene, diketopyrrolopyrrole, perylene, quinacridone, indigoid, dioxazine, and phthalocyanine. These inorganic and organic pigments may be used individually or in combination.

[0065] (The layer including the surface opposite to the surface on the side of resin layer A: resin layer B) The laminated film of the present invention is a laminated film having at least a resin layer A and a base layer, but the layer including the surface opposite to the surface on the side of resin layer A is a layer that contains at least resin and is a different layer from resin layer A. For example, if the laminated film of the present invention has a two-layer structure of resin layer A and a base layer, the layer including the surface opposite to the surface on the side of resin layer A refers to the base layer. As another example, if the laminated film of the present invention has a three-layer structure of resin layer A, a base layer and resin layer B, and each layer is laminated in this order, the layer including the surface opposite to the surface on the side of resin layer A refers to resin layer B. The resin layer B refers to, for example, a layer having a thickness of up to 250 μm, and preferably has release properties that prevent blocking when the laminated film is wound into a roll on the surface on the side of resin layer A.

[0066] The laminated film of the present invention preferably has a polycarbonate probe tack maximum value F on the surface of resin layer A side of 0.098 to 0.245 N / mm². 2 With regard to improving adhesion with low-melting-point alloys and suppressing blocking when wound into a roll, it is preferable that the base layer and resin layer B include a polyolefin resin containing carboxylic acid groups and / or a polyolefin resin containing a carboxylic acid metal base, including a layer including the surface opposite to the surface on the resin layer A side. The preferred composition and content of the polyolefin resin containing carboxylic acid groups and / or the polyolefin resin containing a carboxylic acid metal base is preferably 90% by mass or less, and more preferably 80% by mass or less, of an ethylene-acrylic acid copolymer having an acid content of 6 to 15% by mass as determined by FT-IR measurement and / or an ethylene-methacrylic acid copolymer having an acid content of 6 to 15% by mass as determined by FT-IR measurement.

[0067] By setting the content of polyolefin resins containing carboxylic acid groups and / or polyolefin resins containing carboxylic acid metal bases in the base layer and resin layer B to the above-mentioned preferred range, when the laminated film of the present invention is used as a surface protective film, good adhesion with the low-melting-point alloy cast on the base layer and resin layer B is maintained, and blocking with resin layer A is suppressed when wound into a roll, allowing for easy unwinding. This is also preferable from the viewpoint of exhibiting uniform stretchability of the laminated film.

[0068] Furthermore, the base material layer and resin layer B in the present invention may also contain other olefin resins from the viewpoint of adjusting adhesion with low-melting-point alloys, tackiness with resin layer A when wound into a roll, and obtaining good transportability and handling during use.

[0069] Examples of other olefin resins mentioned above include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, low-crystalline or amorphous ethylene-α-olefin copolymers, crystalline polypropylene, low-crystalline polypropylene, amorphous polypropylene, propylene-ethylene copolymers (random copolymers and / or block copolymers), propylene-α-olefin copolymers, propylene-ethylene-α-olefin copolymers, polybutene, and 4-methyl-1-pentene-α-olefin copolymers, which may be used alone or in combination. The α-olefin is not particularly limited as long as it can be copolymerized with ethylene or propylene, and examples of preferred olefins include ethylene, propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-pentene, and 1-heptene.

[0070] Among the olefin resins mentioned above, one or more selected from low-density polyethylene, linear low-density polyethylene, ethylene-α-olefin copolymer, propylene-α-olefin copolymer, polybutene, crystalline polypropylene, low-crystalline polypropylene, amorphous polypropylene, and 4-methyl-1-pentene-α-olefin copolymer are preferably used.

[0071] In the present invention, when an olefin resin is used in a layer including the surface opposite to the surface of resin layer A, its content is preferably 60% by mass or less, more preferably 40% by mass or less, and even more preferably 20% by mass or less, when the resin of the base layer and resin layer B is taken as 100% by mass.

[0072] The melt flow rate (measured under the conditions of MFR, 190°C, and 2.16 kg) of the olefin resin is preferably 0.5 g / 10 min or more, more preferably 1.0 g / 10 min or more, and even more preferably 2.0 g / 10 min or more, from the viewpoint of productivity and stability when laminating with adjacent layers. Furthermore, the MFR of the olefin resin is preferably 30 g / 10 min or less, more preferably 25 g / 10 min or less, and even more preferably 20 g / 10 min or less, from the same viewpoint as above.

[0073] Furthermore, when the laminated film of the present invention is wound into a roll, it is preferable to include an olefin resin containing a 4-methyl-1-pentene copolymer in order to suppress blocking with the resin layer A and to further suppress contamination during the processing steps.

[0074] Examples of olefin resins containing the above-mentioned 4-methyl-1-pentene units include Mitsui Chemicals' "TPX(registered trademark)" DX310, "TPX(registered trademark)" DX231, "TPX(registered trademark)" MX004, "Absortomer(registered trademark)" EP-1013, and "Absortomer(registered trademark)" EP-1001, among which 4-methyl-1-pentene·α-olefin copolymers, such as those disclosed in Japanese Patent Application Publication No. 2013-194132, are preferably used. The content of the above-mentioned olefin resin containing the 4-methyl-1-pentene units is preferably 2% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, based on 100% by mass of the resin in the base layer and resin layer B. Furthermore, the content of the 4-methyl-1-pentene·α-olefin copolymer is preferably 30% by mass or less, and more preferably 20% by mass or less, of 100% by mass of the resin in the base layer and resin layer B, from the viewpoint of ensuring adhesion with the low-melting-point alloy. By including an olefin resin containing the 4-methyl-1-pentene copolymer in the base layer and resin layer B, when the laminated film of the present invention is used as a surface protective film, good adhesion with the low-melting-point alloy cast on the base layer and resin layer B is maintained, and blocking with resin layer A is suppressed when wound into a roll, allowing for easy unwinding.

[0075] The materials constituting the resin of the base layer and resin layer B preferably contain lubricants such as silicone resins, fluororesins, fatty acid metal salts, fatty acid amides, inorganic particles, and organic particles, from the viewpoint of suppressing blocking with resin layer A. In particular, from the viewpoint of improving transportability and unwinding from a roll state, it is preferable to use inorganic particles or organic particles. For example, the materials constituting the resin of the base layer and resin layer B preferably contain 0.5 to 5% by mass of organic particles made of ultra-high molecular weight polyethylene, when the entire resin layer having a surface opposite to the surface on the side of resin layer A is considered as 100% by mass. When organic particles made of ultra-high molecular weight polyethylene are used, they have higher compatibility with the base layer and resin layer B compared to other particles, making them easy to disperse, and reducing the likelihood of particle detachment during transport and customer use processes. In particular, from the viewpoint of improving transportability, unwinding from a roll state, and suppressing blocking with resin layer A, the average particle size of the organic particles is preferably 1 to 20 μm. From the same viewpoint, 5 to 20 μm is more preferable, and 9 to 20 μm is even more preferable. If the average particle size is less than 1 μm, the surface roughness of the base layer and resin layer B becomes small, which may result in insufficient transportability and unwinding from a roll. If the average particle size exceeds 20 μm, when wound into a roll, the protrusions of the base layer and resin layer B may bite into resin layer A, worsening blocking and making unwinding difficult, or the protrusions may be transferred to resin layer A, reducing the adhesive strength of resin layer A. From a similar viewpoint, when the entire base layer and resin layer B is considered as 100% by mass, the content of the above particles is more preferably 0.5 to 4% by mass, and even more preferably 1 to 2% by mass. If the content is less than 0.5% by mass, the surface roughness becomes small, which may reduce transportability and unwinding from a roll. Furthermore, if the amount exceeds 5% by mass, the protrusions of the base layer and resin layer B may bite into resin layer A, causing blocking and making unwinding difficult. Alternatively, the shape of the particle protrusions may be transferred to the surface of resin layer A, increasing the surface roughness of the surface of resin layer A and reducing the adhesive strength.

[0076] Here, the method for measuring the average particle size of inorganic and organic particles involves using the equivalent circle diameter obtained by image processing from transmission electron microscope images of the particles. The equivalent circle diameter is measured for 50 particles, and the average value is taken as the average particle size. The term "ultra-high molecular weight polyethylene" here refers to polyethylene with a weight-average molecular weight of 1 million or more, as measured by gel permeation chromatography.

[0077] In this invention, fine particles of "Mipelon®" PM-200 can be preferably used as the ultra-high molecular weight polyethylene.

[0078] Next, the method for manufacturing the laminated film of the present invention will be described.

[0079] The method for manufacturing the laminated film of the present invention is not particularly limited. For example, in the case of a three-layer laminated structure having a resin layer A, a base layer, and a layer (resin layer B) including the surface opposite to the surface on the side of resin layer A in this order, examples include a so-called co-extrusion method in which the resin compositions constituting each layer are melt-extruded from separate extruders and laminated together in a die, or a method in which the resin layer A, the base layer, and the layer (resin layer B) including the surface opposite to the surface on the side of resin layer A are melt-extruded individually and then laminated by a lamination method. However, from the viewpoint of productivity, it is preferable to manufacture by the co-extrusion method. The materials constituting each layer may be purchased materials as they are, or mixed using a Henschel mixer or the like, or all or part of the materials for each layer may be kneaded in advance. As for the co-extrusion method, known methods such as the inflation method and the T-die method can be used, but from the viewpoint of excellent thickness accuracy and surface shape control, the hot-melt co-extrusion method using the T-die method is particularly preferred.

[0080] When manufactured by co-extrusion, the components of resin layer A, the base material layer, and the layer (resin layer B) including the surface opposite to the surface on the side of resin layer A are each extruded from a melt extruder, laminated and integrated inside a T-die, and co-extruded. The film is then cooled and solidified with a metal cooling roll to form a film, and the laminated film is obtained by winding it into a roll. The form in which the film is wound into a roll is not particularly limited; the laminated film alone may be wound, or a release liner may be attached separately to the resin layer A side of the laminated film before it is wound into a roll. However, from the viewpoint of cost and productivity, it is more preferable to wind only the laminated film of the present invention into a roll with the base material layer and resin layer B in contact with the surface on the side with resin layer A and the opposite surface, in this case the surface opposite to the surface on the side of resin layer A.

[0081] The laminated film of the present invention can be used as a surface protection film to prevent scratches and dirt from adhering during the manufacturing, processing, and transportation of synthetic resin plates, metal plates, glass plates, etc. It can be particularly preferably used as a surface protection film to be bonded to curved surfaces such as optical instruments and eyeglass lenses, and is most preferably used as a surface protection film for eyeglass lenses.

[0082] In the present invention, from the viewpoint of preventing damage and dirt adhesion during manufacturing, processing, and transportation, it is preferable that the molded body has the laminated film of the present invention. Examples of the molded body include synthetic resin plates, metal plates, and glass plates.

[0083] Furthermore, in the present invention, it is preferable that the manufacturing process of the molded article includes, in this order, a step of attaching the laminated film of the present invention, a step of processing the molded article, and a step of peeling off the laminated film.

[0084] Examples of the aforementioned processing include cutting, punching, bending, polishing, surface modification, bonding, and lamination.

[0085] When the laminated film of the present invention is used as a surface protective film for eyeglass lenses, it can be used in processes such as the following. In eyeglass lenses, polishing is performed as necessary for surface finishing. This polishing process involves casting a low-melting-point alloy to the back of the lens polishing surface, integrating it with the lens, attaching this block-shaped low-melting-point alloy to a fixed shaft, and polishing by pressing the rotating polishing surface against it. In this case, a removable surface protective film is attached to the back surface before casting the low-melting-point alloy to protect the lens surface and ensure adhesion with the alloy. The adhesive side of the surface protective film stretches when it adheres to the back surface of the lens during polishing, and has the effect of cutting the stretched film. It then has the effect of being easily peeled off after polishing in the polishing process, and the surface of the surface protective film opposite the adhesive side has heat resistance that allows the low-melting-point alloy to be cast at a temperature above the melting point of the alloy, and has the effect of adhering to the cooled and solidified alloy. [Examples]

[0086] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. The measurement and evaluation of various physical properties were carried out by the following methods, and unless otherwise specified, these were performed in a room at 23°C.

[0087] (1) Thickness Using a microtome, ultrathin sections with a width of 5 mm and a cross-section in the width-thickness direction of the laminated film were prepared, and these sections were coated with platinum to serve as observation samples. Next, the cross-sections of the laminated film were observed at an acceleration voltage of 2.5 kV using a Hitachi S-4800 field emission differential electron microscope, and the thicknesses of the substrate layer, resin layer A, and the layer including the surface opposite to the surface on the side of resin layer A (resin layer B) were measured from arbitrary points in the observation image. The observation magnification was 5,000x when measuring the thickness of resin layer A and the layer including the surface opposite to the surface on the side of resin layer A (resin layer B), and 1,000x when measuring the thickness of the substrate layer. Furthermore, the same measurements were performed a total of 10 times, and the arithmetic mean was used as the thickness of the substrate layer, resin layer A, and the layer including the surface opposite to the surface on the side of resin layer A (resin layer B), respectively.

[0088] (2) Melt Flow Rate (MFR) Using a melt indexer manufactured by Toyo Seiki Seisakusho, the MFR of the raw materials used in the examples and comparative examples was measured in accordance with JIS K7210-1 (2014) under conditions of 230°C and 2.16 kg load, or 190°C and 2.16 kg load.

[0089] (3) Shear storage modulus Samples were prepared by melt-molding pellets made from the styrene-based elastomer and olefin-based elastomer used in the examples and comparative examples to a thickness of 1 mm. Measurements were performed using a TA Instruments AR2000ex rheometer. The temperature was lowered from 200°C to -20°C at a rate of 20°C / min, and then increased from -20°C to 40°C at a rate of 10°C / min while dynamic shear deformation was performed at a frequency of 1 Hz and a strain of 0.01%. The storage modulus G'(25) at 25°C during the heating process was evaluated.

[0090] (4) Maximum tensile modulus when under tension from 20% to 100% Using a tensile testing machine (Orientec's universal testing machine "Tensilon®"), five tensile tests were performed on the laminated film in the extrusion direction (MD direction) at a temperature of 23°C and a speed of 300 mm / min, in accordance with JIS K 7113-1995. The maximum tensile modulus at 20% to 100% tension was calculated for each state, and the average value was taken as the maximum tensile modulus of the laminated film at 20% to 100% tension. The test specimens used for measurement were strip-shaped with a width of 10 mm and a length of 100 mm, and the chuck distance was 50 mm.

[0091] (5) Tear strength (Trouser method) In accordance with JIS K7128-1:1998, laminated film was cut to a width of 50 mm and a length of 150 mm. A half-cut was made in the center of the cut film width, and the tear strength was measured using a tensile testing machine (Orientec universal testing machine "Tensilon®") when the film was torn. The measurement was performed five times in the extrusion direction (MD direction) of the laminated film, and the average value was taken as the tear strength of the laminated film.

[0092] (6) MD / TD stress ratio at 100% tensile strength Using a tension testing machine (Orientec's universal testing machine "Tensilon®"), in accordance with JIS K 7113-1995, five tensile tests were performed on the laminated film in both the extrusion direction (MD direction) and the width direction (TD direction) at a temperature of 23°C and a speed of 300 mm / min. The average value of the stress at 100% tension was used as the tensile stress of each laminated film, and the MD / TD stress ratio at 100% tension was calculated by dividing the MD tensile stress by the TD tensile stress. The test specimens used for measurement were strip-shaped with a width of 10 mm and a length of 100 mm, and the chuck distance was 50 mm.

[0093] (7) Water contact angle The water contact angle of the surface opposite to the surface of resin layer A was measured using an automatic contact angle meter (DM-501) manufactured by Kyowa Interface Science Co., Ltd. and the analysis software FAMAS. Pure water was used for the measurement, with a drop volume of 2 microliters. Five measurements were performed, and the average value was taken as the water contact angle of the laminated film.

[0094] (8) Maximum tack F of polycarbonate probe The cut samples were aged for 24 hours in a 23°C atmosphere. Using a Lesca TAC1000 tacking tester, a 5mm diameter polycarbonate probe was brought into contact with the surface of resin layer A of the laminated film under the following conditions. The maximum load at which the probe was peeled off was read, and the stress per unit area was calculated by dividing this by the probe area. The test was performed five times for each type of laminated film, and the average value was defined as the maximum probe tack value F on resin layer A of the laminated film. Temperature: 23℃ Sample placement holding time: 5 minutes Contact speed, peeling speed: 2 mm / second Pressing load: 2.94N Contact time: 2 seconds Probe model number: φ5mm PC probe for tacking test machine (TAC1000).

[0095] (9) Peeling strength after storage at 23°C The surface of the resin layer A side of a laminated film cut to a size of 150 mm in the MD direction and 25 mm in the TD direction was bonded to a stainless steel plate (SUS430BA treated, 0.5 mm thick) measuring 200 mm vertically and 40 mm horizontally using a roll press machine (special pressure roller manufactured by Yasuda Seiki Seisakusho) at 23°C with a bonding pressure of 0.1 MPa. Next, the surface of the resin layer A side of a laminated film cut to a size of 150 mm in the MD direction and 25 mm in the TD direction was placed on the surface (base layer or resin layer B) opposite to the surface of the bonded sample (the resin layer A side), and bonded using a roll press machine (special pressure roller manufactured by Yasuda Seiki Seisakusho) at 23°C with a bonding pressure of 0.1 MPa. After that, 50 mm of the laminated film that was not in contact with the stainless steel plate was peeled off. Next, after 24 hours of storage in a 23°C room, a tensile test was performed using a tensile testing machine (Orientec's universal testing machine "Tensilon®") by gripping the stainless steel plate with the lower chuck and gripping the laminated film at a point where it had been peeled 50 mm with the upper chuck. A peel test was performed in the MD direction at a tensile speed of 300 mm / min and a peel angle of 180°. Five tests were performed on each type of laminated film, and the arithmetic mean was defined as the peel force of the laminated film after storage at 23°C.

[0096] <Raw materials> • SEBS-1: Commercially available styrene-based elastomer (Kraton SEBS, “Kraton®” G1645, MFR 3.3g / 10min (measured at 230℃), G′(25) 0.4MPa) • SEBS-2: Commercially available styrene-based elastomer (SEBS manufactured by Asahi Kasei, "ToughTec®" H1052, MFR 13g / 10min (measured at 230℃), G'(25) 1.8MPa) • Terpene phenol resins: Commercially available tackifiers (Yasuhara Chemical's Terpene Phosphate YS Polystar U UH115) PE-1: Commercially available low-density polyethylene (MFR is 5.0 g / 10 min (measured at 190°C), density is 931 kg / m³) 3 ) • PE-2: Commercially available linear low-density polyethylene (MFR 0.4 / 10 min (measured at 190°C), density 928 kg / m³) 3 ) • PE-3: Commercially available linear low-density polyethylene (MFR of 3.8 g / 10 min (measured at 190°C), density 903 kg / m³) 3 ) PE-4: Commercially available high-density polyethylene (MFR 5.0 / 10 min (measured at 190°C), density 950 kg / m³) 3 ) • PE-5: Commercially available low-density polyethylene (MFR of 15g / 10min (measured at 190℃), density 900kg / m³) 3 )·Olefin resin-1:Olefin resin containing 4-methyl-1-pentene units (Mitsui Chemicals "Absortomer (registered trademark)" EP-1001, MFR of 10g / 10min (measured at 230℃)) • Pigment masterbatch consisting of pigment MB: PE-1 95% by mass, phthalocyanine blue 3% by mass, and titanium dioxide 2% by mass. • EMAA: Ethylene-methacrylic acid copolymer (Mitsui Dow Polychemicals' "Nucrel®" AN4213C (acid content of 11% by mass, calculated by FT-IR method, MFR of 10g / 10min (measured at 190°C)) • PE particle masterbatch: PE-1 90% by mass and polyethylene particles with an average particle size of 10 μm (Mitsui Chemicals "Mipelon®" PM-200) consisting of PE-1 90% by mass and 10% by mass. • Olefin resin-2: Olefin resin containing 4-methyl-1-pentene units (Mitsui Chemicals "Absortomer (registered trademark)" EP-1013, MFR of 10g / 10min (measured at 230℃)).

[0097] (Example 1) The constituent resins for each layer were prepared as follows.

[0098] Resin layer A: 80% by mass of G1645 and 20% by mass of UH115 were used, which were pre-mixed and chipped using a twin-screw extruder.

[0099] The base layer consisted of 70% by mass of PE-1 and 30% by mass of PE-2.

[0100] The layer (resin layer B) including the surface opposite to the surface on side of resin layer A: 85% by mass of EMAA, 10% by mass of PE particles MB, and 5% by mass of olefin resin-2 were used.

[0101] Next, the constituent resins of each layer were fed into the extruders of a T-die composite film-making machine, which has three extruders. The discharge rate of each extruder was adjusted so that resin layer A was 15 μm thick, the substrate layer was 95 μm thick, and the layer including the surface opposite to the surface of resin layer A was 10 μm thick. The layers were then laminated in this order and extruded from the composite T-die at an extrusion temperature of 200°C. The resulting film was cast onto a roll with a surface temperature controlled to 40°C, and the formed film was wound up to obtain a laminated film.

[0102] (Examples 2-8, Comparative Examples 1-4) A laminated film was obtained in the same manner as in Example 1, except that the compositions were as shown in the table. The evaluation results are shown in the table.

[0103] (Example 9) The composition constituting resin layer A consisted of 80% by mass of G1645 and 20% by mass of UH115, while the composition constituting the base layer consisted of 75% by mass of EMAA, 10% by mass of PE-2, 10% by mass of PE particles MB, and 5% by mass of olefin resin-2. The materials were fed into each of the two extruders of a T-die composite film-making machine, and the discharge rate of each extruder was adjusted so that resin layer A was 15 μm thick and the base layer was 105 μm thick. The layers were laminated in this order and extruded from the composite T-die at an extrusion temperature of 200°C. The resulting film was cast onto a roll with a surface temperature controlled to 40°C, and wound to obtain a laminated film. The evaluation results are shown in the table.

[0104] [Table 1] [Industrial applicability]

[0105] Because the laminated film of the present invention has sufficient adhesion and conformability to the adherend, it can be preferably used as a surface protective film for products made of various materials such as synthetic resins, metals, and glass.

Claims

1. A laminated film having an adhesive resin layer A and a base layer, The resin layer A contains 60 to 90% by mass of styrene-based elastomer and 10 to 40% by mass of terpene-based resin in 100% by mass. The maximum polycarbonate probe tack F on the surface of resin layer A is 0.098 to 0.245 N / mm². A laminated film that satisfies (a) and (b) below. (a) Maximum tensile modulus of elasticity at 20% to 100% elongation in the extrusion direction (MD) is 1.0 to 20 MPa (b) Tear strength in the extrusion direction (MD) of 4.9 to 49 N / mm

2. The laminated film according to claim 1, wherein the stress ratio (stress in MD / stress in TD) between the extrusion direction (MD) and the width direction (TD) when stretched to 100% is 1.0 to 2.

0.

3. The laminated film according to claim 1 or 2, wherein the water contact angle of the surface opposite to the surface on the side of resin layer A is 90° or more and 110° or less.

4. A laminated film according to any one of claims 1 to 3, wherein the surface on the side of resin layer A and the surface opposite to the surface on the side of resin layer A are bonded at a pressure of 0.1 MPa, and the 180° peel strength after 24 hours of storage is 5.88 N / 25 mm or less.

5. A laminated film according to any one of claims 1 to 4, wherein the base layer contains a coloring agent.

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