Substrate film for dicing film, dicing film, and manufacturing method

Abstract

To provide a base material film for a dicing film having sufficient flexibility and transparency and excellent blocking resistance, the dicing film, and a manufacturing method for the same.SOLUTION: A base material film for a dicing film, comprises a crystalline polypropylene and a polyolefin-based elastomer. The polyolefin-based elastomer comprises at least one copolymer formed from at least two copolymerizable monomers including at least two α-olefins other than ethylene selected from linear α-olefins and / or branched α-olefins. An enthalpy of melting of the polyolefin elastomer exceeds 0 J / g and is 15 J / g or less, or is 25 J / g or more and 40 J / g or less, and satisfies a specific range of an internal haze, gloss of at least one surface, a melting point, and a melting enthalpy.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a substrate film of an adhesive film (hereinafter referred to as "dicing film") that is attached to the front and / or back surface of a silicon wafer or the like for the purpose of surface protection when dicing (cutting and separating) the silicon wafer or the like, a dicing film using the same, and methods for producing the same. [Background technology]

[0002] Semiconductor chips are produced by forming a large number of chips together on a large-diameter silicon wafer and then dicing the wafer into individual chips. The dicing process is often carried out after laminating a dicing film onto the front and / or back surfaces of the silicon wafer (on which a large number of semiconductor chips are formed) for the purposes of protecting the surfaces of the semiconductor chips and fixing and picking up the individual semiconductor chips that have been cut.

[0003] In particular, if the dicing tape lacks flexibility during the expanding and pick-up processes, it can cause problems such as the dicing tape coming off the ring frame; the dicing tape breaking; narrow spacing between cut wafers resulting in low pick-up yield; and chips flying off and breaking due to the load on the semiconductor wafer. Therefore, substrate films for dicing films must be highly flexible.

[0004] Traditionally, films made of flexible polyvinyl chloride resin compositions have been widely used as base films for dicing films due to their many advantages, including a good balance between heat resistance and flexibility, tensile properties suitable for the expanding process, high transparency, and low cost. However, films made of flexible polyvinyl chloride resin compositions contain large amounts of plasticizer, which can migrate into the adhesive, destabilizing the adhesive properties (reducing or increasing adhesive strength), and can contaminate semiconductor chips and other devices. To address this issue, films made of polypropylene resins or polypropylene resin compositions have been proposed as base films for dicing films (see, for example, Patent Documents 1 to 3). However, their performance as base films for dicing films falls short of that of films made of flexible polyvinyl chloride resin compositions. Furthermore, films made of polypropylene resins or polypropylene resin compositions, when given sufficient flexibility and transparency for use as base films for dicing films, have the disadvantage of insufficient blocking resistance. There is a demand for a substrate film for a dicing film that has sufficient flexibility and transparency and excellent blocking resistance, but such a substrate film has not yet been developed.

[0005] Dicing films generally include a substrate film for dicing films and a pressure-sensitive adhesive layer formed on the surface thereof. To improve the adhesion (anchoring) between the substrate film for dicing films and the pressure-sensitive adhesive layer, corona discharge treatment is often performed by irradiating the pressure-sensitive adhesive layer-forming surface of the substrate film for dicing films with corona discharge energy. However, corona discharge treatment can cause stickiness on the treated film surface, making blocking more likely to occur. In practice, corona discharge treatment can be performed on one or both sides of the film. In either case, corona discharge treatment can cause the disadvantage of making blocking more likely to occur. A substrate film for a dicing film that has the required properties and can effectively prevent blocking, especially when the surface is subjected to a corona discharge treatment (hereinafter simply referred to as "corona surface treatment"), is desirable. However, such a substrate film has not yet been developed. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-290001 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-089138 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-127161 [Patent Document 4] International Publication No. 2011 / 055803 [Patent Document 5] Japanese Patent Application Laid-Open No. 2015-093918 [Patent Document 6] Japanese Patent Application Laid-Open No. 2015-096580 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a substrate film suitable for use in a dicing film, which can replace films of soft polyvinyl chloride resin compositions, has sufficient flexibility and transparency, and is excellent in blocking resistance, and also to provide a dicing film using the same, and methods for producing the same. Another object of the present invention is to provide a substrate film suitable for use in a dicing film, which can replace films of soft polyvinyl chloride resin compositions, has sufficient flexibility and transparency, and is excellent in blocking resistance, and is capable of effectively preventing blocking, particularly when subjected to a corona surface treatment; a dicing film using the same; and methods for producing the same. [Means for solving the problem]

[0008] As a result of extensive research, the present inventors have found that the above object can be achieved by using a specific resin film.

[0009] That is, the various aspects of the present invention are as follows. [1]. A substrate film for a dicing film, (A) crystalline polypropylene and (B) polyolefin elastomer; The above-mentioned base film for dicing film satisfies the following properties (i) to (iv): (i) Internal haze is 20% or less; (ii) At least one side has a gloss of 40% or less; (iii) a melting point of 150°C or higher; (iv) The enthalpy of fusion is 30 to 90 J / g. [2]. The substrate film for dicing film according to item [1] above, wherein the gloss on both sides is 40% or less. [3]. The substrate film for dicing film according to the above item [1] or [2] further satisfies the following properties (v-1) and (v-2): (v-1) the tensile modulus in the machine direction is 600 MPa or less; (v-2) The difference between the tensile yield stress and the tensile lower yield stress in the machine direction is 2.5 MPa or less. [4]. The substrate film for a dicing film according to the above item [1] or [2], wherein the polyolefin elastomer (B) is a random copolymer composed of propylene and butene-1. [5]. The base film for a dicing film according to item [4] above, wherein the mass ratio of the crystalline polypropylene region to the amorphous polypropylene region in the random copolymer is within the range of 40:60 to 60:40. [6]. The substrate film for dicing film according to item [4] or [5] above, wherein the mass ratio of the amorphous polypropylene region in the random copolymer to the total mass of the (A) crystalline polypropylene and the (B) random copolymer polyolefin elastomer is 10% or more. [7]. A dicing film comprising the substrate film for a dicing film according to any one of the above items [1] to [6]. [8]. A method for producing a substrate film for a dicing film according to any one of the above items [1] to [6], (1) A step of continuously extruding a molten film from a T-die using an extrusion device equipped with an extruder and a T-die; (2) feeding the molten film between a first roll which is a rotating smooth roll or a textured roll and a second roll which is a rotating textured roll, and pressing the molten film between the first roll and the second roll; and (3) A step of wrapping the pressed film in the above step (2) around the first roll and sending it to the next rotating roll. A method comprising: [9]. The method according to item [8] above, wherein the embossed roll is a matte rubber roll or a matte metal roll.

[10] . The method according to item [8] or [9] above, wherein the smooth roll is a mirror-finished metal roll.

[11] . The method for producing a dicing film according to the above item [7], (1) A step of forming a substrate film for a dicing film by the method according to any one of the above items [8] to

[10] ; and (2) A step of forming a pressure-sensitive adhesive layer on the surface of the dicing film substrate film obtained in the above step (1) having a gloss of 40% or less. A method comprising:

[12] . The method for producing a dicing film according to the above item [7], (1) A step of forming a substrate film for a dicing film by the method according to any one of the above items [8] to

[10] ; and (2) If there is a surface of the substrate film for dicing film obtained in the above step (1) where the gloss is 50% or more, a step of forming a pressure-sensitive adhesive layer on that surface. A method comprising: [Effects of the Invention]

[0010] The film of the present invention fundamentally solves the problems caused by plasticizers in films of flexible polyvinyl chloride resin compositions by not incorporating plasticizers. Furthermore, the film of the present invention is excellent in flexibility, transparency, and blocking resistance. Preferred films of the present invention also have excellent heat resistance, flexibility, transparency, solvent resistance, and blocking resistance, and have tensile properties suitable for the expanding process. The excellent flexibility of the substrate film for dicing films, and therefore the dicing film itself, can effectively prevent problems during the expanding and pick-up processes, such as the dicing tape coming off the ring frame; the dicing tape breaking; narrow spacing between cut wafers resulting in reduced pick-up yield; and chips scattering and breakage due to load on the semiconductor wafer. In addition to the above properties, more preferred films of the present invention also have excellent blocking resistance, especially when subjected to corona surface treatment. Therefore, the film of the present invention can be suitably used as a substrate film for dicing films. The film of the present invention can be suitably produced by the manufacturing method of the present invention. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a DSC curve of the film of Example 1. [Figure 2] 1 is a conceptual diagram of a stress-strain curve. [Figure 3] 1 is a DSC curve of the crystalline polypropylene (A-1) used in the examples. [Figure 4] 1 is a DSC curve of the polyolefin elastomer (B-1) used in the examples. [Figure 5] FIG. 1 is a conceptual diagram of a film-forming apparatus used in the examples. [Figure 6] 1 is a 13C-NMR spectrum of the polyolefin elastomer (B-1) used in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0012] As used herein, the term "resin" is used to include resin mixtures containing two or more resins, as well as resin compositions containing components other than resin. As used herein, the term "film" is used interchangeably with "sheet." As used herein, the terms "film" and "sheet" refer to materials that can be industrially wound into rolls. The term "plate" refers to materials that cannot be industrially wound into rolls. Furthermore, as used herein, laminating one layer and another layer in order includes both directly laminating the layers and laminating the layers with one or more additional layers, such as an anchor coat, interposed between them.

[0013] In this specification, the term "equivalent to or greater than" in relation to a numerical range means a certain numerical value or more than a certain numerical value. For example, "20% or greater" means 20% or more than 20%. The term "equivalent to or less than" in relation to a numerical range means a certain numerical value or less than a certain numerical value. For example, "20% or less" means 20% or less than 20%. The symbol "to" in relation to a numerical range means a certain numerical value, more than a certain numerical value and less than another certain numerical value, or another certain numerical value. Here, the other certain numerical value is a number greater than the certain numerical value. For example, "10 to 90%" means 10%, more than 10% and less than 90%, or 90%. Furthermore, the upper and lower limits of a numerical range can be arbitrarily combined, and embodiments incorporating such combinations can be interpreted. For example, from a description of the numerical range of a certain characteristic such as "usually 10% or more, preferably 20% or more. On the other hand, it is usually 40% or less, preferably 30% or less," or "usually 10 to 40%, preferably 20 to 30%," it can be read that the certain characteristic is 10 to 40%, 20 to 30%, 10 to 30%, or 20 to 40% in one embodiment.

[0014] Other than in the examples, or where otherwise specified, all numerical values ​​used in the specification and claims should be understood to be modified by the term "about." Without attempting to limit the application of the doctrine of equivalents to the claims, each numerical value should be construed in light of the number of significant digits and by applying ordinary rounding techniques.

[0015] 1. Substrate film for dicing film The substrate film for dicing film of the present invention has (i) an internal haze of typically 20% or less, preferably 15% or less, more preferably 12% or less, and even more preferably 10% or less. By having the internal haze (i) be typically 20% or less, the transparency required for the dicing film, such as visibility during laser marking, can be sufficiently ensured. There is no particular lower limit for the internal haze (i) from the viewpoint of transparency, and the lower the better.

[0016] In this specification, the internal haze (i) is measured by preparing two glass plates with smooth surfaces, one of which is coated with paraffin oil, sandwiching a sample between the paraffin oil-coated surfaces of the two glass plates to form a measurement piece, and then measuring the haze according to JIS K7136:2000. More specifically, the internal haze in this specification can be measured by the method described in the examples below.

[0017] The substrate film for dicing film of the present invention (ii) has a gloss of at least one surface of typically 40% or less. Here, gloss is a 60-degree gloss value measured in accordance with JIS Z8741:1997. More specifically, the gloss in this specification can be measured by the method described in the examples below. Hereinafter, the surface of the substrate film for dicing films of the present invention, which has a gloss adjusted to 40% or less, may be referred to as the "matte surface." In the art, the "matte surface" is also sometimes referred to as the "matte surface" or "matt-treated surface." Since the matte surface of the substrate film for dicing films of the present invention typically has a gloss of 40% or less, sufficient blocking resistance can be achieved even when the substrate film for dicing films is imparted with sufficient flexibility. Furthermore, by forming a pressure-sensitive adhesive layer on the matte surface, external haze caused by the unevenness of the matte surface is canceled, ensuring sufficient transparency for the dicing film. Furthermore, since the matte surface has large unevenness, forming a pressure-sensitive adhesive layer on the matte surface can improve the adhesive strength between the substrate film for dicing films of the present invention and the pressure-sensitive adhesive layer. From the viewpoint of blocking resistance, the gloss of at least one surface (matte surface) of the substrate film for dicing film is preferably 35% or less, more preferably 30% or less, even more preferably 25% or less, even more preferably 20% or less, even more preferably 15% or less, even more preferably 10% or less, and most preferably 6% or less. On the other hand, from the viewpoint of smoothing the surface of the pressure-sensitive adhesive layer, the gloss of at least one surface (matte surface) of the substrate film for dicing film may preferably be 1% or more.

[0018] The arithmetic mean roughness (Ra) of the matte surface of the substrate film for dicing film of the present invention may be typically 0.5 to 10 μm, preferably 1 to 5 μm, from the viewpoint of blocking resistance and smoothing the surface of the pressure-sensitive adhesive layer. Herein, the arithmetic mean roughness (Ra) is measured in accordance with JIS B0601:2013. More specifically, the arithmetic mean roughness (Ra) herein can be measured by the method described in the examples below.

[0019] In one embodiment, the gloss of one side of the substrate film for dicing films of the present invention may be typically 40% or less, and the gloss of the other side may be typically 50% or more. Hereinafter, the side of the substrate film for dicing films of the present invention having a gloss adjusted to 50% or more may be referred to as the "glossy side." When the gloss of the glossy side is typically 50% or more, sufficient transparency as a substrate film for dicing films is ensured. From the viewpoint of transparency, the gloss of the glossy side of the substrate film for dicing films is typically 50% or more, preferably 55% or more, more preferably 60% or more, even more preferably 65% ​​or more, more preferably 70% or more, even more preferably 75% or more, even more preferably 80% or more, and most preferably 85% or more. On the other hand, from the viewpoint of blocking resistance, the gloss of the glossy side of the substrate film for dicing films may be preferably 140% or less, more preferably 130% or less.

[0020] In another embodiment, the substrate film for dicing films of the present invention may generally have a gloss of 40% or less on each side. That is, both sides of the substrate film for dicing films of the present invention may be matte surfaces. In this embodiment, the gloss of each matte surface is adjusted independently, so the gloss of both surfaces may be substantially equal to or different from each other. Since the gloss of each matte surface of the substrate film for dicing film of this embodiment is usually 40% or less, sufficient blocking resistance can be exhibited even when sufficient flexibility is imparted to the substrate film for dicing film. Furthermore, by forming a pressure-sensitive adhesive layer on the matte surface, external haze caused by unevenness of the matte surface is canceled, and sufficient transparency as a dicing film is ensured. Furthermore, since the matte surface has large unevenness, forming a pressure-sensitive adhesive layer on the matte surface can achieve the effect of improving the adhesive strength between the substrate film for dicing film of the present invention and the pressure-sensitive adhesive layer. Furthermore, since the gloss of each matte side of the substrate film for dicing films of this embodiment is usually 40% or less, excellent blocking resistance can be obtained even when the surface of the substrate film for dicing films on which the pressure-sensitive adhesive layer is formed is subjected to corona discharge treatment in order to improve adhesion (anchoring ability) with the pressure-sensitive adhesive layer. Furthermore, this advantage can be obtained whether the corona discharge treatment is applied to one side or both sides of the film. The gloss of each matte surface of the substrate film for dicing films according to this embodiment is preferably 35% or less, more preferably 30% or less, even more preferably 25% or less, even more preferably 20% or less, still more preferably 15% or less, even more preferably 10% or less, and most preferably 6% or less, from the viewpoint of blocking resistance. On the other hand, the gloss of each matte surface of the substrate film for dicing films according to this embodiment may be preferably 1% or more, from the viewpoint of smoothing the surface of the pressure-sensitive adhesive layer.

[0021] The substrate film for dicing film of the present invention has (iii) a melting point of usually 150°C or higher, preferably 155°C or higher, and more preferably 160°C or higher. The (iii) melting point of 150°C or higher can adequately ensure the heat resistance required for a dicing film. Furthermore, the solvent resistance required when forming a pressure-sensitive adhesive layer on the surface (usually the matte surface) of the substrate film for dicing film of the present invention can be adequately ensured. From the viewpoint of heat resistance and solvent resistance, the (iii) melting point is preferably higher.

[0022] The substrate film for dicing film of the present invention has (iv) a melting enthalpy of usually 30 J / g or more, preferably 40 J / g or more, and preferably 50 J / g or more from the viewpoints of heat resistance, solvent resistance, and blocking resistance. On the other hand, the substrate film for dicing film of the present invention has (iv) a melting enthalpy of usually 90 J / g or less, preferably 85 J / g or less, more preferably 80 J / g or less, even more preferably 75 J / g or less, and still more preferably 70 J / g or less from the viewpoint of flexibility.

[0023] In this specification, the (iii) melting point and (iv) melting enthalpy are calculated from a DSC first melting curve measured in accordance with JIS K7121-1987 using a differential scanning calorimeter (DSC) under a program in which the sample is held at 25°C for 5 minutes and then heated to 190°C at a rate of 10°C / min. The (iii) melting point is the peak-top temperature of the melting peak appearing in the DSC first melting curve. When two or more melting peaks are observed, the peak-top temperature of the melting peak with the greatest peak-top height is taken as the (iii) melting point. Figure 1 shows an example of DSC measurement for Example 1. The bottom curve in Figure 1 is the DSC first melting curve, the top curve is the DSC crystallization curve, and the middle curve is the DSC second melting curve. It should be noted that the melting peak appearing in the DSC first melting curve of a crystalline polypropylene resin composition usually has a gently sloping, long base on the low-temperature side; and that the baseline should be drawn so that the line extending from the high-temperature side baseline to the low-temperature side in Figure 1 of JIS K7121-1987, section 9. How to read DTA or DSC curves, coincides with the line extending from the same low-temperature side baseline to the high-temperature side. More specifically, the melting point and enthalpy of fusion in this specification can be measured by the method described in the examples below.

[0024] The tensile modulus of elasticity measured under conditions in which the machine direction of the substrate film for dicing film of the present invention is the tensile direction (hereinafter abbreviated as "tensile modulus MD") may be usually 800 MPa or less, preferably 700 MPa or less, more preferably 600 MPa or less, and even more preferably 550 MPa or less from the viewpoint of flexibility. On the other hand, the tensile modulus of elasticity MD may be usually 100 MPa or more, preferably 200 MPa or more, more preferably 300 MPa or more, and even more preferably 350 MPa or more from the viewpoint of stability in film formation.

[0025] The tensile modulus (hereinafter abbreviated as "tensile modulus TD") measured under conditions in which the transverse direction (direction perpendicular to the machine direction) of the substrate film for dicing film of the present invention is the tensile direction may be, from the viewpoint of flexibility, usually 800 MPa or less, preferably 700 MPa or less, more preferably 600 MPa or less, and even more preferably 550 MPa or less. On the other hand, from the viewpoint of stability in film formation, the tensile modulus TD may be usually 100 MPa or more, preferably 200 MPa or more, more preferably 300 MPa or more, and even more preferably 350 MPa or more.

[0026] The ratio of the tensile modulus MD to the tensile modulus TD of the substrate film for dicing film of the present invention (tensile modulus MD / tensile modulus TD) may be usually 0.5 to 1.5, preferably 0.7 to 1.5, more preferably 0.8 to 1.5, and even more preferably 0.8 to 1.2, from the viewpoint of ensuring that the film is uniformly stretched in the expanding step following the dicing step.

[0027] In this specification, the tensile modulus (MD) is calculated in accordance with JIS K7127:1999 using a test specimen punched from a film in the shape of a Type 5 test specimen (Figure 2 of the JIS standard) with the machine direction of the film as the tensile direction, at a tensile speed of 200 mm / min and a temperature of 23°C. The stress-strain curve (hereinafter referred to as the "SS curve") is obtained by performing a tensile test at a temperature of 23°C, and is calculated from the slope determined from two points as specified in Section 10.3.2 of JIS K7161-1:2014, regardless of the provisions of Section 10.3.2 of JIS K7161-1:2014. Furthermore, regardless of the provisions of Section 10.3.2 of JIS K7161-1:2014, σ1 is the stress (MPa) at strain ε1 = 0.8%, and σ2 is the stress (MPa) at strain ε2 = 1.6%. The tensile modulus TD is measured and calculated in the same manner, except that test pieces are punched out so that the tensile direction is the transverse direction of the film. More specifically, the tensile modulus MD and the tensile modulus TD in this specification can be measured by the method described in the examples below.

[0028] The stress difference (Δσ) (hereinafter abbreviated as "stress difference MD") between the tensile yield stress (σy) and the tensile lower yield stress (σ1) (the stress at the point (ε1) at which the tensile stress, which had been decreasing with increasing tensile strain after the tensile strain exceeds the tensile yield strain (εy), begins to increase again) (σ1) of the substrate film for dicing film of the present invention, measured under conditions where the machine direction is the tensile direction, is usually 3 MPa or less, preferably 2.5 MPa or less, more preferably 2 MPa or less, even more preferably 1 MPa or less, and even more preferably 0.5 MPa or less, from the viewpoint of suitability for the expanding step of dicing. From the viewpoint of expandability, the smaller the stress difference MD, the better.

[0029] The stress difference (Δσ) between the tensile yield stress (σy) and the tensile yield stress (σ1) of the substrate film for dicing film of the present invention, measured under conditions where the transverse direction (direction perpendicular to the machine direction) is the tensile direction (hereinafter abbreviated as "stress difference TD"), may be usually 3 MPa or less, preferably 2 MPa or less, more preferably 1 MPa or less, and even more preferably 0.5 MPa or less, from the viewpoint of suitability for the expanding step of dicing. From the viewpoint of expandability, the smaller the stress difference TD, the better.

[0030] In this specification, the stress difference (MD) is calculated in accordance with JIS K7127:1999. A test specimen was punched from a film to the shape of Type 5 test specimen (Figure 2 of the JIS standard) with the machine direction of the film aligned in the tensile direction. A tensile test was conducted at a tensile speed of 200 mm / min and a temperature of 23°C. From the SS curve, the tensile yield stress (σy) was calculated as the stress at the tensile yield strain (εy) (note the JIS Annex A) and the tensile yield stress (σ1) was calculated as the stress at the strain (ε1). A conceptual diagram of the stress-strain curve is shown in Figure 2. The stress difference (TD) was measured and calculated in the same manner, except that the test specimen was punched with the transverse direction of the film aligned in the tensile direction. More specifically, the stress difference MD and the stress difference TD in this specification can be measured by the method described in the examples below.

[0031] The thickness of the substrate film for a dicing film of the present invention is not particularly limited and may be appropriately selected taking into consideration its use as a substrate film for a dicing film. The thickness of the substrate film for a dicing film of the present invention may be usually 30 to 300 μm, preferably 50 to 200 μm, and more preferably 70 to 150 μm.

[0032] The substrate film for a dicing film of the present invention contains (A) a crystalline polypropylene and (B) a polyolefin elastomer. Each component will be described below.

[0033] (A) Crystalline polypropylene The substrate film for a dicing film of the present invention contains the above-mentioned component (A) crystalline polypropylene. The above-mentioned component (A) crystalline polypropylene functions to impart excellent heat resistance and solvent resistance to the substrate film for a dicing film of the present invention.

[0034] The crystalline polypropylene component (A) is a resin that primarily contains structural units derived from propylene and has high crystallinity. Here, "primarily contains structural units derived from propylene" means that the content of structural units derived from propylene is usually 50 mol% or more, preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and typically 90 to 100 mol%. Regarding the crystalline polypropylene component (A), "having high crystallinity" means that the melting enthalpy (measurement method described below) is usually 50 J / g or more. In one embodiment, the melting enthalpy of the crystalline polypropylene component (A) may be preferably 60 J / g or more, more preferably 65 J / g or more, and even more preferably 70 J / g or more.

[0035] The crystalline polypropylene component (A) may have a mesodiad fraction (the proportion of structural units derived from two consecutive propylene units that have an isotactic structure) of usually 80 mol% or more, preferably 90 mol% or more, more preferably 95 mol% or more, and typically 97 to 100 mol% in the case of isotactic polypropylene. The racemic diad fraction (the proportion of structural units derived from two consecutive propylene units that have a syndiotactic structure) of usually 80 mol% or more, preferably 90 mol% or more, more preferably 95 mol% or more, and typically 97 to 100 mol% in the case of syndiotactic polypropylene.

[0036] Examples of the crystalline polypropylene component (A) include propylene homopolymers and copolymers (including block copolymers and random copolymers) of propylene with one or more small amounts of other α-olefins (e.g., ethylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene). Such block copolymers of propylene with small amounts of other α-olefins as component (A) may contain amorphous regions or amorphous blocks in addition to crystalline regions or crystalline blocks.

[0037] Among these, the component (A) crystalline polypropylene is preferably a block copolymer of propylene and a small amount of one or more other α-olefins, from the viewpoint of setting the melting point and melting enthalpy of the dicing film substrate film within the specified ranges and setting the melting point and melting enthalpy of the component (A) crystalline polypropylene within the preferred ranges described below. The component (A) crystalline polypropylene can be a mixture of one or more of these block copolymers.

[0038] From the viewpoints of heat resistance and solvent resistance, the melting point of the crystalline polypropylene component (A) may be preferably 150°C or higher, more preferably 155°C or higher, and even more preferably 160°C or higher. From the viewpoints of heat resistance and solvent resistance, the melting point of the crystalline polypropylene component (A) is preferably higher. Furthermore, from the viewpoints of heat resistance and solvent resistance, the crystalline polypropylene component (A) preferably does not exhibit a sub-peak with a peak top temperature of less than 150°C in the second melting curve described below.

[0039] The fusion enthalpy of the crystalline polypropylene component (A) may be generally 50 J / g or more, more preferably 60 J / g or more, and even more preferably 70 J / g or more, from the viewpoints of heat resistance and solvent resistance. On the other hand, the fusion enthalpy of the component (A) may be preferably 110 J / g or less, more preferably 100 J / g or less, from the viewpoint of flexibility, although this may vary depending on the blending ratio of the crystalline polypropylene component (A) to the polyolefin elastomer component (B).

[0040] In this specification, the melting point and melting enthalpy of the crystalline polypropylene component (A) are calculated from a second melting curve (the melting curve measured during the final heating process) measured using a differential scanning calorimeter (DSC) in accordance with JIS K7121-1987, using a program that involves holding at 190°C for 5 minutes, cooling to -10°C at 10°C / min, holding at -10°C for 5 minutes, and then heating to 190°C at 10°C / min. The melting point is the peak-top temperature of the melting peak that appears in the second melting curve. When two or more melting peaks are observed, the melting point is the peak-top temperature of the melting peak with the greatest peak-top height. Figure 3 shows an example of DSC measurement of the following component (A-1) used in the examples. The lower curve in Figure 3 is the DSC second melting curve, and the upper curve is the DSC crystallization curve. It should be noted that the melting peak appearing in the second melting curve of a DSC of crystalline polypropylene usually has a long, gently sloping base on the low-temperature side; and that the baseline should be drawn so that the line extending the high-temperature side baseline to the low-temperature side coincides with the line extending the same low-temperature side baseline to the high-temperature side in Figure 1 of JIS K7121-1987, Section 9. How to read DTA or DSC curves.

[0041] From the viewpoint of film-forming properties, the melt mass flow rate of the component (A) may be preferably 0.1 to 50 g / 10 min, more preferably 0.5 to 20 g / 10 min, and even more preferably 1 to 10 g / 10 min. The melt mass flow rate of the component (A) is measured in accordance with JIS K7210-1:2014 under conditions of 230°C and 21.18 N.

[0042] (B) Polyolefin elastomer The substrate film for a dicing film of the present invention contains the polyolefin elastomer component (B), which provides the substrate film for a dicing film of the present invention with excellent flexibility and tensile properties suitable for the expanding process.

[0043] The polyolefin elastomer (B) is an elastomer that mainly contains structural units derived from α-olefins (usually 50 mol % or more, preferably 70 mol % or more, more preferably 90 mol % or more, typically 95 to 100 mol %).

[0044] Here, the term "elastomer" in relation to the polyolefin elastomer component (B) means that the melting enthalpy (the measurement method will be described later) is usually 45 J / g or less. In one embodiment, the melting enthalpy of the polyolefin elastomer of component (B) may be preferably 15 J / g or less, more preferably 10 J / g or less, even more preferably 5 J / g or less, and most preferably 0 J / g (no melting peak is observed in the DSC second melting curve). In another embodiment, the melting enthalpy of the component (B) polyolefin elastomer may be preferably in the range of 10 J / g or more and 20 J / g or less, more preferably in the range of 10 J / g or more and 15 J / g or less. In yet another embodiment, the melting enthalpy of the component (B) polyolefin elastomer may be preferably in the range of 25 J / g or more and 40 J / g or less, more preferably in the range of 30 J / g or more and 40 J / g or less, and even more preferably in the range of 30 J / g or more and 35 J / g or less.

[0045] In this specification, the melting point and melting enthalpy of the polyolefin elastomer (B) are calculated in accordance with JIS K7121-1987 using a differential scanning calorimeter (DSC) from a second melting curve (the melting curve measured during the final heating process) measured using a program that involves holding at 190°C for 5 minutes, cooling to -50°C at 10°C / min, holding at -50°C for 5 minutes, and then heating to 190°C at 10°C / min. The melting point is the peak-top temperature of the melting peak that appears in the second melting curve. When two or more melting peaks are observed, the melting point is determined to be the peak-top temperature of the melting peak with the greatest peak top height. It should also be noted that the melting peak appearing in the second melting curve of an elastomer's DSC usually has a gently extending, long tail on both the high-temperature and low-temperature sides; and that the baseline should be drawn so that the line extending the high-temperature baseline toward the low-temperature side coincides with the line extending the low-temperature baseline toward the high-temperature side, as shown in Figure 1 of JIS K7121-1987, Section 9. How to read DTA or DSC curves. Figure 4 shows an example of DSC measurement of the following component (B-1) used in the examples. The lower curve in Figure 4 is the DSC second melting curve, and the upper curve is the DSC crystallization curve. No melting peak is observed in the DSC second melting curve of the following component (B-1).

[0046] Examples of the α-olefins include linear α-olefins and branched α-olefins. Examples of the linear α-olefins include ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene. Examples of the branched α-olefins include 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3-ethyl-1-pentene, 4,4-dimethyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4-ethyl-1-hexene, and 3-ethyl-1-hexene. Among these, α-olefins having 2 to 8 carbon atoms are preferred. One or more of these α-olefins can be used as the α-olefin.

[0047] The polyolefin elastomer (B) may contain, in addition to the α-olefin, structural units derived from monomers copolymerizable with the α-olefins. Examples of the copolymerizable monomers include non-conjugated diene compounds such as 5-ethylidene-2-norbornene; aromatic vinyl compounds such as styrene; unsaturated carboxylic acids such as acrylic acid and methacrylic acid; and unsaturated carboxylic anhydrides such as maleic anhydride. One or more of these copolymerizable monomers may be used.

[0048] Examples of the polyolefin elastomer component (B) include copolymers (including block copolymers and random copolymers) of ethylene and one or more other α-olefins (e.g., propylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene); copolymers (including block copolymers and random copolymers) of propylene and one or more α-olefins (e.g., ethylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene); copolymers (including block copolymers and random copolymers) of 4-methyl-1-pentene and one or more α-olefins (e.g., ethylene, propylene, 1-butene, 1-hexene, and 1-octene); and copolymers (including block copolymers and random copolymers) of ethylene, propylene, and 5-ethylidene-2-norbornene.

[0049] Among these, the polyolefin elastomer component (B) is preferably a copolymer of 4-methyl-1-pentene and one or more other α-olefins (sometimes referred to in the art as a "TPX-based elastomer") from the viewpoint of a balance between flexibility and blocking resistance. Such copolymers are more preferably those containing 50 to 90 mol%, preferably 60 to 80 mol%, and more preferably 65 to 75 mol% of structural units derived from 4-methyl-1-pentene. The total of all types of structural units is 100 mol%. The fusion enthalpy of such copolymers of 4-methyl-1-pentene and one or more other α-olefins may be preferably 15 J / g or less, more preferably 10 J / g or less, even more preferably 5 J / g or less, and most preferably 0 J / g (no melting peak is observed in the DSC second melting curve).

[0050] Among these, the polyolefin elastomer component (B) is preferably a copolymer containing structural units derived from 4-methyl-1-pentene and structural units derived from propylene, from the viewpoints of the balance between flexibility and blocking resistance and miscibility with the crystalline polypropylene component (A). Such copolymers typically contain 50 to 90 mol%, preferably 60 to 80 mol%, and more preferably 65 to 75 mol% of structural units derived from 4-methyl-1-pentene, and typically 10 to 50 mol%, preferably 20 to 40 mol%, and more preferably 25 to 35 mol% of structural units derived from propylene. The total of all types of structural units is 100 mol%. Examples of such copolymers include copolymers of 4-methyl-1-pentene and propylene, and copolymers of one or more of 4-methyl-1-pentene, propylene, and other α-olefins.

[0051] In another embodiment, from the viewpoint of the balance between flexibility and blocking resistance, the polyolefin elastomer component (B) is preferably a random copolymer composed of propylene and butene-1. The mass ratio of the crystalline polypropylene domain to the amorphous polypropylene domain in the random copolymer of propylene and butene-1 is estimated to generally vary within a range of 10:90 to 90:10, preferably 15:85 to 85:15, more preferably 20:80 to 80:20, even more preferably 25:75 to 75:25, and even more preferably 30:70 to 70:30. This is believed to provide a favorable balance between flexibility and blocking resistance. From the viewpoint of obtaining such properties, the enthalpy of fusion of the random copolymer of propylene and butene-1 may preferably be in the range of 10 J / g to 20 J / g, more preferably 10 J / g to 15 J / g. Furthermore, the mass ratio of the crystalline polypropylene region to the amorphous polypropylene region in the random copolymer composed of propylene and butene-1 is preferably 35:65 to 65:35, more preferably 40:60 to 60:40, even more preferably 45:55 to 55:45, and most preferably substantially 50:50 (e.g., 48:52 to 52:48) from the viewpoint of the balance between flexibility and blocking resistance, as described above, and from the viewpoint of obtaining excellent blocking resistance even when the base film for dicing film is subjected to a corona surface treatment. From the viewpoint of obtaining such properties, the melting enthalpy of the random copolymer composed of propylene and butene-1 may be preferably in the range of 25 J / g to 40 J / g, more preferably in the range of 30 J / g to 40 J / g, and even more preferably in the range of 30 J / g to 35 J / g.

[0052] From the viewpoint of film-forming properties, the melt mass flow rate of the polyolefin elastomer (B) is preferably 0.1 to 50 g / 10 min, more preferably 0.5 to 20 g / 10 min, and even more preferably 1 to 10 g / 10 min. The melt mass flow rate of the polyolefin elastomer (B) is measured in accordance with JIS K7210-1:2014 under conditions of 230°C and 21.18 N.

[0053] The blending ratio of the component (A) crystalline polypropylene and the component (B) polyolefin elastomer can be determined appropriately, taking into account the melting enthalpy of the component (A) crystalline polypropylene and the melting enthalpy of the component (B) polyolefin elastomer, from the viewpoint of achieving the melting enthalpy (iv) of 30 to 90 J / g of the substrate film for dicing film of the present invention. Considering the examples described below, the melting enthalpies are generally additive. Therefore, for example, when the melting enthalpy (iv) of 60 J / g is desired, the blending amount (b parts by mass) of the component (B) per 100 parts by mass of the component (A) can be determined by solving the following equation (1) for b: (100·ΔH A +b ΔHB ) / (100+b)=60 (1) Here, ΔH A is the fusion enthalpy (J / g) of the above component (A), and ΔH B is the fusion enthalpy (J / g) of the above component (B). When the desired fusion enthalpy (iv) above is generalized to ΔH, the following equation (2) can be solved for b. (100·ΔH A +b ΔH B ) / (100+b)=ΔH (2) where ΔH is the desired melting enthalpy (J / g) of (iv) above, ΔH A is the fusion enthalpy (J / g) of the above component (A), and ΔH B is the fusion enthalpy (J / g) of the above component (B).

[0054] As demonstrated in the examples described below, it has been found that the greater the mass ratio of the amorphous polypropylene region in the random copolymer as component (B) relative to the total mass of components (A) and (B) contained in the base film for dicing film (the greater the mass ratio of the amorphous polypropylene region relative to the total mass of the base film for dicing film), the more flexible the film tends to be.

[0055] The substrate film for dicing film of the present invention may contain any component (single or multiple) known in the art other than the above components (A) and (B). The proportion of such optional components is not particularly limited, but may be, for example, 5% by mass or less based on the total mass of the components constituting the film. Preferably, plasticizers are not included in such optional components.

[0056] 2. Film forming method The method for producing the substrate film for dicing film of the present invention is not particularly limited, and the film can be produced by any method. A preferred method for producing the substrate film for the dicing film of the present invention is, for example, (1) A step of continuously extruding a molten film from a T-die using an extrusion device equipped with an extruder and a T-die; (2) A step of supplying and inserting the molten film between a first roll which is a rotating smooth roll or a textured roll and a second roll which is a rotating textured roll, and pressing the molten film between the first roll and the second roll (when both sides are to be "matte surfaces" ("matte-treated surfaces"), a textured roll is used as the first roll); and (3) A step of wrapping the pressed film in the above step (2) around the first roll and sending it to the next rotating roll. The method can include the following.

[0057] The extruder used in step (1) is not particularly limited, and any extruder can be used, including, for example, a single-screw extruder, a co-rotating twin-screw extruder, and a counter-rotating twin-screw extruder.

[0058] To prevent deterioration of the raw material resin, it is preferable to purge the inside of the extruder with nitrogen. It is also preferable to dry the raw material resin before using it for film formation. It is also preferable to transport these resins dried in a dryer directly from the dryer and feed them into the extruder.

[0059] The T-die used in step (1) is not particularly limited, and any T-die can be used, including, for example, a manifold die, a fishtail die, and a coat hanger die.

[0060] The temperature set at the outlet (lip) of the T-die may be usually 200°C or higher, preferably 220°C or higher, and more preferably 230°C or higher, from the viewpoint of stably carrying out the step of continuously extruding the molten film. On the other hand, from the viewpoint of suppressing deterioration of the raw material resin, the temperature set at the T-die may be usually 300°C or lower, preferably 280°C or lower, and more preferably 260°C or lower.

[0061] The smooth roll used in step (2) (if used) is appropriately selected from the viewpoint of making the gloss of the shiny side of the substrate film for dicing film of the present invention 50% or more. The smooth roll is preferably a mirror-finish roll from the viewpoint of making the gloss of one side of the substrate film for dicing film of the present invention preferably 55% or more, more preferably 60% or more, even more preferably 65% ​​or more, more preferably 70% or more, even more preferably 75% or more, still more preferably 80% or more, and most preferably 85% or more.

[0062] The mirror-finished roll is a roll whose surface has been mirror-finished. Examples of the mirror-finished roll include mirror-finished rolls whose surfaces are made of metal, ceramic, or rubber. The surface of the mirror-finished roll can be chrome-plated, iron-phosphorus alloy-plated, or hard carbon-treated by PVD or CVD to protect it from corrosion and scratches.

[0063] The mirror-finishing can be carried out by any method, for example, by polishing with fine abrasive grains to make the arithmetic mean roughness (Ra) of the surface of the mirror-finished body preferably 100 nm or less, more preferably 50 nm or less, or the ten-point mean roughness (Rz) preferably 500 nm or less, more preferably 250 nm or less.

[0064] In this specification, the arithmetic mean roughness (Ra) and the ten-point mean roughness (Rz) are measured in accordance with JIS B0601:2013.

[0065] The smooth roll used in step (2) (if used) functions as a cooling roll. The smooth roll is preferably a metal roll from the viewpoint of completely cooling and solidifying the film when it is sent to the next rotating roll in step (3). The smooth roll is more preferably a mirror-finished metal roll from the viewpoint of making the gloss of the shiny side of the substrate film for dicing film of the present invention 50% or more and from the viewpoint of completely cooling and solidifying the film when it is sent to the next rotating roll in step (3).

[0066] The surface temperature of the smooth roll used in step (2) (if used) is appropriately selected from the viewpoints of increasing the gloss of the shiny side of the dicing film substrate film of the present invention to 50% or more, ensuring that the film is completely cooled and solidified when sent to the next rotating roll in step (3), and preventing condensation on the surface of the smooth roll. The surface temperature of the smooth roll may be typically 80°C or lower, preferably 60°C or lower, and more preferably 50°C or lower, from the viewpoints of increasing the degree of supercooling (the temperature difference between the surface temperature of the smooth roll and the temperature of the molten film immediately before contact with the smooth roll) to increase the gloss of the shiny side to 50% or more, and ensuring that the film is completely cooled and solidified when sent to the next rotating roll in step (3). On the other hand, the surface temperature of the smooth roll may be typically 15°C or higher, preferably 20°C or higher, and more preferably 25°C or higher, depending on the temperature and humidity of the film-forming environment, from the viewpoint of preventing condensation on the surface of the smooth roll.

[0067] The embossed roll used in step (2) is appropriately selected from the viewpoint of making the gloss of the matte surface of the dicing film substrate film of the present invention 40% or less. The embossed roll is a roll whose surface is embossed, typically a matte-finished roll (matte roll). Examples of the embossed roll include embossed rolls whose surfaces are made of metal, ceramic, or rubber. When used as the second roll, the embossed roll is preferably a rubber-surfaced embossed roll from the viewpoints of low thermal conductivity (cooling efficiency), which makes it easy to reduce the gloss, and ease of film formation (e.g., the reduced risk of damage to the smooth roll). From the above viewpoints, the embossed roll used as the second roll is more preferably a matte rubber roll. On the other hand, when used as the first roll, the embossed roll may preferably be made of metal, typically a matte metal roll, from the viewpoint of ensuring that the film is completely cooled and solidified when it is sent to the next rotating roll in step (3).

[0068] The surface of the satin-finished rubber roll is made of rubber and is satin-finished. The surface roughness / grit of the satin-finished rubber roll is appropriately selected from the viewpoint of making the gloss of the matte surface of the substrate film for dicing film of the present invention 40% or less. The arithmetic mean roughness (Ra) of the surface of the satin-finished rubber roll may be preferably 0.5 to 10 μm, more preferably 1 to 5 μm. The surface of the satin-finished metal roll is made of metal and is satin-finished. The surface roughness / grit is the same as that of the satin-finished rubber roll.

[0069] The surface temperature of the shiboron used in step (2) is appropriately selected from the viewpoints of making the gloss of the matte surface of the substrate film for dicing film of the present invention 40% or less, suppressing or preventing problems such as adhesion of a molten film to the shiboron, and preventing condensation on the surface of the shiboron. From the viewpoint of suppressing or preventing problems such as adhesion of a molten film to the shiboron, the surface temperature of the shiboron may be typically 80°C or less, preferably 70°C or less, and more preferably 60°C or less. On the other hand, from the viewpoint of making the gloss of the matte surface of the substrate film for dicing film of the present invention 40% or less and preventing condensation on the surface of the shiboron, the surface temperature of the shiboron may be typically 15°C or more, preferably 30°C or more, and more preferably 40°C or more, depending on the surface material of the shiboron and the temperature and humidity of the film-forming environment. In one embodiment, cooling water may be applied to the shiboron as needed in step (2).

[0070] In the step (3), the film pressed in the step (2) is wrapped around the first roll and sent to the next rotating roll. By wrapping the molten film around the first roll, it becomes easy to ensure that the molten film is completely cooled and solidified when sent to the next rotating roll.

[0071] FIG. 5 is a conceptual diagram of one embodiment of the film-forming apparatus used in the examples (for producing a substrate film for a dicing film having a matte surface (matte-finished surface) on one side and a glossy surface on the other side). The raw resin is turned into a molten film 3 by an extrusion device equipped with an extruder 1 and a T-die 2, and is continuously extruded from the T-die 2. The extruded molten film 3 is then fed between a rotating first roll (a smooth roll in this case) 4 and a rotating second roll (a grained roll) 5, where it is pressed between the first roll 4 and the second roll 5. The pressed molten film 3 is then embraced by the first roll 4 and sent to the next rotating roll 6, where it has completely cooled and solidified into a film 7.

[0072] 3. Dicing film The dicing film of the present invention is a dicing film using the substrate film for a dicing film of the present invention as a substrate film. The pressure-sensitive adhesive layer of the dicing film of the present invention is usually formed directly or via an anchor coat on the matte surface of the substrate film for a dicing film of the present invention.

[0073] The adhesive for forming the adhesive layer is not particularly limited, and any adhesive can be used. Examples of adhesives for forming the adhesive layer include acrylic adhesives such as poly(meth)acrylic acid alkyl esters and copolymers of (meth)acrylic acid alkyl esters with other monomers, rubber adhesives such as natural rubber and butyl-isoprene rubber, polyurethane adhesives, polyester adhesives, polystyrene adhesives, and silicone adhesives.

[0074] The adhesive for forming the adhesive layer is preferably an adhesive with excellent transparency, from the viewpoint of ensuring the transparency required for a dicing film, for example, sufficient visibility during laser marking. Here, "an adhesive with excellent transparency" refers to an adhesive with a visible light transmittance of typically 50% or more, preferably 70% or more, more preferably 80% or more, and even more preferably 85% or more. Visible light transmittance can be calculated as the ratio of the integrated area of ​​the transmission spectrum of the adhesive at wavelengths of 380 to 780 nanometers, measured using a Shimadzu Corporation spectrophotometer "Solid Spec-3700" (trade name) and a quartz cell with an optical path length of 10 mm, to the integrated area of ​​the transmission spectrum assuming a transmittance of 100% over the entire wavelength range of 380 to 780 nanometers.

[0075] As the adhesive for forming the adhesive layer, an adhesive whose adhesive strength can be reduced by heat curing or active energy ray curing is also preferred. The reduced adhesive strength allows the dicing film to be easily peeled cleanly from the workpiece without leaving any adhesive residue. Examples of adhesives whose adhesive strength can be reduced by heat curing or active energy ray curing include adhesives having two or more reactive functional groups per molecule (e.g., amino groups, vinyl groups, epoxy groups, methacryloxy groups, acryloxy groups, isocyanate groups, etc.); and adhesive compositions containing such adhesives and at least one of an isocyanate curing agent, a photopolymerization initiator, and an organic peroxide.

[0076] The thickness of the pressure-sensitive adhesive layer is not particularly limited and can be any thickness. The thickness of the pressure-sensitive adhesive layer is usually about 1 to 25 μm, and preferably about 5 to 20 μm. [Example]

[0077] Measurement method (i) Internal haze Two float glass plates (2 mm thick) as specified in JIS R3202:2011 were prepared, with paraffin oil ("Moresco White P-350P" (trade name) by MORESCO Corporation) applied to one surface. Next, a sample was sandwiched between the paraffin oil-coated surfaces of the two glass plates to form a measurement piece. The haze was then measured using a turbidity meter "NDH2000" (trade name) by Nippon Denshoku Industries Co., Ltd. in accordance with JIS K7136:2000, and the measured value was taken as the internal haze.

[0078] (ii) Gloss (60° gloss value) Gloss (60-degree gloss value) was measured in accordance with JIS Z8741:1997 using a multi-angle glossmeter "GM-268" (product name) manufactured by Konica Minolta, Inc. Measurements were taken on both sides of the sample. In the table, the value for the side that was the smooth roll (mirror-finish metal roll) side during film formation is listed in the "gloss of glossy side" column, and the value for the other side (the side that was the grained roll (matt rubber roll) side) is listed in the "gloss of matte side" column.

[0079] (iii) Melting point The melting point of the substrate film for dicing film was measured in accordance with JIS K7121-1987 using a PerkinElmer differential scanning calorimeter "Diamond DSC" (trade name). The DSC first melting curve was measured using a temperature program in which the temperature was held at 25°C for 5 minutes and then increased to 190°C at a heating rate of 10°C / min. The melting point was calculated as the peak-top temperature of the melting peak appearing in the curve. When two or more melting peaks were observed, the peak-top temperature of the melting peak with the greatest peak-top height was taken as the melting point. The peak-top temperatures of subpeaks (melting peaks other than the melting peak with the greatest peak-top height) were also recorded in the subpeak column of the table. Note that a "-" in the subpeak column of the table means that no subpeak was observed (there was only one melting peak). The melting point of the crystalline polypropylene component (A) is calculated from a second melting curve (the melting curve measured during the final heating process) measured in accordance with JIS K7121-1987 using a PerkinElmer Diamond DSC differential scanning calorimeter (trade name) according to a program that involves holding the sample at 190°C for 5 minutes, cooling to -10°C at 10°C / min, holding the sample at -10°C for 5 minutes, and then heating the sample to 190°C at 10°C / min. The melting point is the peak-top temperature of the melting peak that appears in the second melting curve. When two or more melting peaks are observed, the melting point is determined to be the peak-top temperature of the melting peak with the greatest peak-top height. It should be noted that the melting peak appearing in the second melting curve of a DSC of crystalline polypropylene usually has a long, gently sloping base on the low-temperature side; and that the baseline should be drawn so that the line extending the high-temperature side baseline to the low-temperature side coincides with the line extending the same low-temperature side baseline to the high-temperature side in Figure 1 of JIS K7121-1987, Section 9. How to read DTA or DSC curves. The melting point of the polyolefin elastomer (B) is calculated from a second melting curve (the melting curve measured during the final heating process) measured in accordance with JIS K7121-1987 using a PerkinElmer Diamond DSC (trade name) differential scanning calorimeter, which is run by holding the sample at 190°C for 5 minutes, cooling to -50°C at 10°C / min, holding the sample at -50°C for 5 minutes, and then heating to 190°C at 10°C / min. The melting point is the peak-top temperature of the melting peak that appears in the second melting curve. When two or more melting peaks are observed, the melting point is determined to be the peak-top temperature of the melting peak with the greatest peak top height. It should also be noted that the melting peak appearing in the second melting curve of an elastomer's DSC usually has a gently extending, long tail on both the high-temperature and low-temperature sides; and that the baseline should be drawn so that the line extending the high-temperature baseline to the low-temperature side, as shown in Figure 1 of JIS K7121-1987, section 9. How to read DTA or DSC curves, coincides with the line extending the same low-temperature baseline to the high-temperature side.

[0080] (iv) Enthalpy of fusion The melting enthalpy of the base film for the dicing film was calculated from the DSC fast melting curve obtained in the above (iii) measurement of the melting point. The enthalpies of fusion of the component (A) crystalline polypropylene and the component (B) polyolefin elastomer were calculated from the DSC second melting curves obtained in the measurement of the melting points in (iii) above.

[0081] (v) Tensile test In accordance with JIS K7127:1999, a Shimadzu Corporation tensile testing machine, Autograph AGS-1kNG (product name), was used to punch out samples from the film into the shape of Type 5 test pieces (Figure 2 of the JIS standard) with the machine direction of the film as the tensile direction. Tensile tests were performed at a tensile speed of 200 mm / min and a temperature of 23°C to obtain a stress-strain curve in the machine direction (hereinafter referred to as the "SS curve"). A transverse SS curve was also obtained by performing measurements in the same manner, except that the samples were punched out so that the tensile direction was the transverse direction (the direction perpendicular to the machine direction).

[0082] (v-1) Tensile modulus The machine direction tensile modulus (referred to in the table as "tensile modulus MD") was calculated from the SS curve in the machine direction obtained in the tensile test (v) above, regardless of the calculation and display of results provisions in JIS K7127:1999, Section 10, using the method based on the slope calculated from two points in JIS K7161-1:2014, Section 10.3.2. Also, regardless of the provisions in JIS K7161-1:2014, Section 10.3.2, where σ1 is the stress (MPa) at strain ε1 = 0.8% and σ2 is the stress (MPa) at strain ε2 = 1.6%. The transverse direction tensile modulus (referred to in the table as "tensile modulus TD") was calculated in the same manner from the SS curve in the transverse direction obtained in the tensile test (v) above. Furthermore, the ratio of the tensile modulus in the machine direction to the tensile modulus in the transverse direction (tensile modulus in the machine direction / tensile modulus in the transverse direction; indicated as "tensile modulus MD / TD" in the table) was calculated.

[0083] (v-2) Stress difference (Δσ) From the machine direction SS curve obtained in the tensile test (v) above, the tensile yield stress (σy) and the tensile bottom yield stress (σ1) were calculated in accordance with Section 10.1 of JIS K7161-1:2014, where σy is the stress at tensile yield strain (εy) (attention being paid to Appendix A of the JIS standard) and σ1 is the stress at strain (ε1), and the machine direction stress difference (Δσ = σy - σ1) was calculated (referred to as "stress difference MD" in the table). Similarly, from the transverse direction SS curve obtained in the tensile test (v) above, the transverse direction stress difference was calculated (referred to as "stress difference TD" in the table).

[0084] (v-3) 5% strain tensile stress, 100% strain tensile stress From the machine direction SS curve obtained in the tensile test (v) above, the 5% strain tensile stress in the machine direction (referred to as "5% modulus MD" in the table) and the 100% strain tensile stress in the machine direction (referred to as "100% modulus MD" in the table) were calculated according to Section 10.1 of JIS K7161-1:2014. Similarly, from the transverse direction SS curve obtained in the tensile test (v) above, the 5% strain tensile stress in the transverse direction (referred to as "5% modulus TD" in the table) and the 100% strain tensile stress in the transverse direction (referred to as "100% modulus TD" in the table) were calculated. Furthermore, the ratio of the 5% strain tensile stress in the machine direction to the 5% strain tensile stress in the transverse direction (5% strain tensile stress in the machine direction / 5% strain tensile stress in the transverse direction; referred to as "5% modulus MD / TD" in the table) was calculated. Similarly, the ratio of the 100% strain tensile stress in the machine direction to the 100% strain tensile stress in the transverse direction (100% strain tensile stress in the machine direction / 100% strain tensile stress in the transverse direction; indicated in the table as "100% modulus MD / TD") was calculated.

[0085] The ratio of the 5% strain tensile stress in the machine direction to the 5% strain tensile stress in the transverse direction may be usually 0.7 to 1.3, preferably 0.8 to 1.2, and more preferably 0.9 to 1.1, from the viewpoint of uniformly stretching the film in the expanding step of dicing. The ratio of the 100% strain tensile stress in the machine direction to the 100% strain tensile stress in the transverse direction may be usually 0.7 to 1.3, preferably 0.8 to 1.2, and more preferably 0.9 to 1.1, from the viewpoint of uniformly stretching the film in the expanding step of dicing.

[0086] (vi) Arithmetic mean roughness (Ra) of matte surface The arithmetic mean roughness (Ra) of the matte surface was measured using a roughness meter "Handysurf E-40A" (product name) manufactured by Tokyo Seimitsu Co., Ltd. in accordance with JIS B0601:2013.

[0087] (vii) Blocking resistance ·Measuring method for blocking resistance (1) Two samples measuring 30 cm in the machine direction and 10 cm in the transverse direction were taken from a film having one matte side and the other glossy side; the matte side of one sample was overlapped with the glossy side of the other sample so that the two pieces of the two samples were approximately aligned; the two samples were sandwiched flat between two 30 cm x 10 cm metal plates so that the two metal plates and the overlapping pieces of the two samples were approximately aligned; a 1 kg weight was placed on top of the samples and the samples were treated at 25°C for 48 hours. The 90° peel force of both samples was then measured at a test speed of 300 mm / min, with the machine direction and peel direction of the samples parallel. In the table, "<0.1" indicates that the 90° peel force was less than 0.1 N / 10 cm. From the viewpoint of blocking resistance, the 90° peel force may be preferably 0.5 N / 10 cm or less, more preferably 0.3 N / cm or less. A smaller 90° peel force is preferable. ·Measuring method for blocking resistance (2) For films with one matte side and the other matte or glossy side, both sides of which had been corona-treated, the 90° peel force of both samples was measured using the same method as described above, except that the sample dimensions were changed to 20 cm in the machine direction and 10 cm in the cross direction, with the matte side overlapping the matte or glossy side, the weight load was changed to 6 kg, the aging conditions were changed to treatment at 80°C for 5 hours, and the test speed was changed to 50 mm / min. ·Measuring method of blocking resistance (3) Films with one matte side and the other matte or glossy side, either uncoated or both corona-treated, were wound into a roll with a width of 10 inches (25.4 cm) under a tension of 2 kg. After leaving the film in a 40°C environment for one week, the peel strength of the wound film was measured using a peel tester when the film was pulled out longitudinally at a position 10 m from the core at a test speed of 200 mm / min.

[0088] (viii) Solvent resistance Three drops of toluene were dropped onto the matte surface (the surface that was the shiborol side during film formation; in Example 2, the surface facing the air chamber) using a dropper, and then the sample was left for 24 hours in an environment at a temperature of 25°C and a relative humidity of 50% (to allow the dropped toluene to dry). The gloss (60-degree gloss value) at the toluene drop location was then measured using the method in test (ii) above. The difference between the gloss at the toluene drop location and the gloss at the matte surface (hereinafter sometimes referred to as the "gloss difference"; gloss difference = gloss at the toluene drop location - gloss at the matte surface) was calculated. When solvent resistance is low, the gloss at the toluene drop location may decrease due to surface roughness or increase due to surface irregularities being dissolved. Therefore, from the viewpoint of solvent resistance, the gloss difference may be preferably -3 to 3%, more preferably -2 to 2%, and even more preferably -1 to 1%. The smaller the absolute value of the gloss difference, the better.

[0089] Raw materials used (A) Crystalline polypropylene (A-1) Novatec BC5FA (trade name), a block polypropylene manufactured by Japan Polypropylene Corporation. MFR 3.5 g / 10 min, melting point 162°C, and melting enthalpy 76 J / g. (A-2) Block polypropylene "VB170A" (trade name) from SunAllomer Co., Ltd. MFR 0.4 g / 10 min, melting point 164°C, melting enthalpy 77 J / g, and shoulder melting peak at 149°C. (A-3) Block polypropylene "VB370A" (trade name) from SunAllomer Co., Ltd. MFR 1.5 g / 10 min, melting point 164°C, melting enthalpy 80 J / g, and shoulder melting peak at 148°C. (A-4) SunAllomer Co., Ltd. block polypropylene "PM870A" (trade name). MFR 17.0 g / 10 min, melting point 164°C, melting enthalpy 87 J / g. (A-5) Prime Polypro S235WC (trade name), a random polypropylene from Prime Polymer Co., Ltd. MFR 11.0 g / 10 min, melting point 134°C, and melting enthalpy 66 J / g. (A-6) Homopolypropylene "PL500A" (trade name) from SunAllomer Co., Ltd. MFR 3.0 g / 10 min, melting point 162 °C, melting enthalpy 104 J / g. (A-7) SunAllomer Co., Ltd. homopolypropylene "PM600A" (trade name). MFR 7.5 g / 10 min, melting point 163 °C, melting enthalpy 102 J / g.

[0090] (B) Polyolefin elastomer (B-1) A copolymer of propylene and 4-methyl-1-pentene (Mitsui Chemicals, Inc.'s polyolefin elastomer "Absortomer EP-1001" (trade name)). 13 The amount of structural units derived from propylene as measured by C-NMR was 28.1 mol %, and the amount of structural units derived from 4-methyl-1-pentene was 71.9 mol %. No melting peak was observed in the second melting curve by DSC. MFR (230°C, 21.18N) was 10 g / 10 min. (B-2) A polyolefin elastomer "Absortomer EP-1013" (trade name) from Mitsui Chemicals, Inc. MFR (230°C, 21.18N) 10g / 10min, melting point 130°C, melting enthalpy 11J / g. (B-3) Sumitomo Chemical Co., Ltd.'s polyolefin elastomer "Tafthren H3712D" (trade name). Propylene / butene-1 random copolymer (butene-1 ratio is 10% by mass or less). Mass ratio of crystalline polypropylene region to amorphous polypropylene region is 15:85. Melting point: 131°C, enthalpy of fusion: 14 J / g. (B-4) Dow Elastomers EPDM "Nodel IP3720P" (trade name). Melting point: 34°C, enthalpy of fusion: 41 J / g. (B-5) Sumitomo Chemical Co., Ltd.'s polyolefin elastomer "Tafthren T3732" (trade name). Propylene / butene-1 random copolymer (containing 5% butene-1 by mass). Mass ratio of crystalline polypropylene region to amorphous polypropylene region: 50:50. Melting point: 129°C, enthalpy of fusion: 32 J / g.

[0091] Example 1 A resin mixture of 100 parts by mass of the component (A-1) and 18 parts by mass of the component (B-1) was used, and a film-forming apparatus (extrusion apparatus having an extruder 1 and a T-die 2, and a film-forming apparatus equipped with a take-up device having a nipping mechanism between a smooth roll (a mirror-finished metal roll) as the first roll 4 and a textured roll (a matte rubber roll: surface arithmetic mean roughness (Ra) 1.5 μm, ten-point mean roughness (Rz) 11.9 μm) as the second roll 5) conceptually shown in FIG. 5 was used. The resin mixture was continuously extruded from the T-die 2 as a molten film 3. Next, the extruded molten film 3 was fed between the rotating first roll 4 and the rotating second roll 5 and pressed between the first roll 4 and the second roll 5. Next, the pressed molten film 3 was wrapped around the first roll 4 and sent to the next rotating roll 6, and a 100 μm-thick film 7 was formed. At this time, the resin temperature at the T-die outlet was 210°C, the surface temperature of the first roll 4 was 25°C, the temperature of the cooling water flowing through the second roll 5 was 16°C, and the take-up speed was 18 m / min. The above tests (i) to (viii) were carried out. Test (vii) Blocking resistance was measured by measurement method (1). The results are shown in Table 1.

[0092] Example 2 A resin mixture of 100 parts by mass of the above component (A-1) and 18 parts by mass of the above component (B-1) was used to produce a 100 μm-thick film using an extrusion device having an extruder 1 and a T-die 2, and a film-forming device equipped with a mirror-finished metal roll (chill roll) and a take-up device having an air chamber, under conditions of a resin temperature at the T-die outlet of 220°C, a surface temperature of the mirror-finished metal roll (chill roll) of 25°C, and a take-up speed of 18 m / min. The above tests (i) to (viii) were carried out. Test (vii) Blocking resistance was measured using measurement method (1). The results are shown in Table 1.

[0093] Examples 3 to 19 Except for using a resin mixture shown in any one of Tables 1 to 4, film formation and measurement and evaluation of physical properties were carried out in the same manner as in Example 1. The results are shown in any one of Tables 1 to 4.

[0094] [Table 1]

[0095] [Table 2]

[0096] [Table 3]

[0097] [Table 4]

[0098] The film of the present invention can be suitably produced by the manufacturing method of the present invention. The preferred film of the present invention has excellent heat resistance, flexibility, transparency, solvent resistance, and blocking resistance, and has tensile properties suitable for the expanding process. Therefore, it can be suitably used as a base film for a dicing film.

[0099] The haze of the substrate film of Example 1 (measured according to JIS K7136:2000 using a turbidity meter "NDH2000" (trade name) manufactured by Nippon Denshoku Industries Co., Ltd.) was 84.8% (the value output by the turbidity meter). Subsequently, a coating material for forming an adhesive layer, consisting of 333 parts by mass (100 parts by mass of solids content equivalent) of Fujikura Kasei Co., Ltd.'s transparent adhesive "ACRYBASE LKG-1013" (trade name), 1 part by mass of Fujikura Kasei Co., Ltd.'s isocyanate curing agent "CL-201" (trade name), and 222 parts by mass of ethyl acetate, was applied to the matte surface of the substrate film of Example 1 using an applicator so that the film thickness after drying would be 10 μm. The coating film was then dried at a temperature of 85 ° C. to form an adhesive layer, and a dicing film was obtained. The haze of the dicing film (measured in accordance with JIS K7136:2000 using a turbidity meter "NDH2000" (trade name) manufactured by Nippon Denshoku Industries Co., Ltd.) was 11.0%. This confirmed that by forming a pressure-sensitive adhesive layer on the matte surface, the external haze caused by the unevenness of the matte surface was canceled, ensuring sufficient transparency as a dicing film.

[0100] Optimization experiment of matte surface treatment conditions when corona surface treatment is applied Example 20 A resin mixture of 70 parts by mass of the component (A-1) and 30 parts by mass of the component (B-5) was used, a film-forming device equipped with a rubber embossing roll having an arithmetic mean roughness (Ra) of 0.5 μm was used as the second roll 5 instead of a rubber embossing roll having an arithmetic mean roughness (Ra) of 1.5 μm, the take-up speed was changed from 18 m / min to 5 m / min, and a corona treatment power supply "AGI-020" manufactured by Kasuga Electric Co., Ltd. was used on both sides of the obtained film, with a discharge amount of 0.20 kW·min / m so that the wetting tension of the corona-treated surface of the film measured in accordance with JIS K6768:1999 was 50 mN / m or more. 2A film was produced in the same manner as in Example 1, except that the corona surface treatment was carried out under the following conditions, and the blocking resistance of the produced film was measured using the measurement method (2) in (vii) above. The wetting tension of the corona surface-treated surface of the film was 56 mN / m. The results are shown in Table 5. The power source and discharge amount used for the corona surface treatment were the same in the following examples.

[0101] Example 21 A film was produced in the same manner as in Example 1, except that a resin mixture of 70 parts by mass of the above component (A-1) and 30 parts by mass of the above component (B-5) was used and both sides of the obtained film were subjected to a corona surface treatment, and the blocking resistance of the produced film was measured using the measurement method (2) in (vii) above. That is, film production and physical property measurements were carried out in the same manner as in Example 20, except that the rubber embossed roll with an arithmetic mean roughness (Ra) of 1.5 μm was not changed as the second roll 5 in Example 1. The results are shown in Table 5.

[0102] Example 22 A film was produced in the same manner as in Example 1, except that a resin mixture of 70 parts by weight of the above component (A-1) and 30 parts by weight of the above component (B-5) was used; a film-producing apparatus was used in which a metal textured roll with an arithmetic mean roughness (Ra) of 0.5 μm was used as the first roll 4 instead of a smooth roll (mirror-finish metal roll); a rubber textured roll with an arithmetic mean roughness (Ra) of 0.5 μm was used as the second roll 5 instead of a rubber textured roll with an arithmetic mean roughness (Ra) of 1.5 μm; and both sides of the film were subjected to a corona surface treatment. The film was then produced and its physical properties were measured using the measurement method (2) in (vii) above. That is, film production and physical property measurements were performed in the same manner as in Example 20, except that a textured roll with an arithmetic mean roughness (Ra) of 0.5 μm was used as the first roll 4 instead of a smooth roll. The results are shown in Table 5.

[0103] Example 23 A film was produced in the same manner as in Example 1, except that a resin mixture of 70 parts by mass of the above component (A-1) and 30 parts by mass of the above component (B-5) was used, a film-producing apparatus equipped with a metal satin-finish embossed roll with an arithmetic mean roughness (Ra) of 0.5 μm was used instead of a smooth roll (mirror-finish metal roll) as the first roll 4, and both sides of the obtained film were subjected to a corona surface treatment. The blocking resistance of the produced film was measured using the measurement method (2) in (vii) above. That is, film production and physical property measurements were performed in the same manner as in Example 22, except that one of the embossed rolls with an arithmetic mean roughness (Ra) of 1.5 μm was used instead of the embossed roll with an arithmetic mean roughness (Ra) of 0.5 μm. The results are shown in Table 5.

[0104] [Table 5]

[0105] The results shown in Table 5 indicate that the greater the arithmetic mean roughness (Ra) of the grain roll used for matte surface treatment, i.e., the greater the depth of the grain transferred to the film surface, the more effectively blocking was suppressed. Furthermore, it was found that when matte surface treatment was applied to both sides of the film, blocking was suppressed more effectively than when matte surface treatment was applied to only one side.

[0106] Optimization experiment of film composition / with or without corona surface treatment / matt surface treatment conditions Example 24 A film was produced in the same manner as in Example 1, except that a resin mixture of 70 parts by mass of the above component (A-1) and 30 parts by mass of the above component (B-5) was used, and the blocking resistance of the produced film was measured using the measurement method (3) in (vii) above. The results are shown in Table 6.

[0107] Example 25 A film was produced in the same manner as in Example 1, except that a resin mixture of 70 parts by mass of the above component (A-1) and 30 parts by mass of the above component (B-5) was used, and a film-producing apparatus equipped with a metallic matte textured roll with an arithmetic mean roughness (Ra) of 0.5 μm was used instead of a smooth roll (mirror-finished metal roll) as the first roll 4, and the blocking resistance of the produced film was measured by the measurement method (3) in (vii) above. That is, film production and physical property measurements were performed in the same manner as in Example 24, except that a metallic matte textured roll with an arithmetic mean roughness (Ra) of 0.5 μm was used instead of a smooth roll (mirror-finished metal roll) as the first roll 4. The results are shown in Table 6.

[0108] Example 26 A film was produced in the same manner as in Example 1, except that a resin mixture of 70 parts by mass of the component (A-1) and 30 parts by mass of the component (B-5) was used and both sides of the film were subjected to a corona surface treatment. The blocking resistance of the produced film was measured by the measurement method (3) in (vii) above. The results are shown in Table 6.

[0109] Example 27 A film was produced in the same manner as in Example 1, except that a resin mixture of 70 parts by mass of the above component (A-1) and 30 parts by mass of the above component (B-5) was used, a film-producing apparatus equipped with a metallic matte textured roll with an arithmetic mean roughness (Ra) of 0.5 μm was used instead of a smooth roll (mirror-finished metal roll) as the first roll 4, and both sides of the obtained film were subjected to a corona surface treatment. The blocking resistance of the produced film was measured using the measurement method (3) in (vii) above. That is, film production and physical property measurements were performed in the same manner as in Example 26, except that a metallic matte textured roll with an arithmetic mean roughness (Ra) of 0.5 μm was used instead of a smooth roll (mirror-finished metal roll) as the first roll 4. The results are shown in Table 6.

[0110] Example 28 A film was produced in the same manner as in Example 1, except that a resin mixture of 70 parts by mass of the above component (A-1) and 30 parts by mass of the above component (B-1) was used and both sides of the obtained film were subjected to a corona surface treatment, and the blocking resistance of the produced film was measured using the measurement method (3) in (vii) above. The results are shown in Table 6.

[0111] Example 29 A film was produced in the same manner as in Example 1, except that a resin mixture of 70 parts by mass of the above component (A-1) and 30 parts by mass of the above component (B-1) was used, a film-producing apparatus equipped with a metallic matte textured roll with an arithmetic mean roughness (Ra) of 0.5 μm was used instead of a smooth roll (mirror-finished metal roll) as the first roll 4, and both sides of the obtained film were subjected to a corona surface treatment. The blocking resistance of the produced film was measured using the measurement method (3) in (vii) above. That is, film production and physical property measurements were performed in the same manner as in Example 28, except that a metallic matte textured roll with an arithmetic mean roughness (Ra) of 0.5 μm was used instead of a smooth roll (mirror-finished metal roll) as the first roll 4. The results are shown in Table 6.

[0112] Example 30 A film was produced in the same manner as in Example 1, except that a resin mixture of 70 parts by mass of the above component (A-1) and 30 parts by mass of the above component (B-2) was used and both sides of the obtained film were subjected to a corona surface treatment, and the blocking resistance of the produced film was measured using the measurement method (3) in (vii) above. The results are shown in Table 6.

[0113] Example 31 A film was produced in the same manner as in Example 1, except that a resin mixture of 70 parts by mass of the above component (A-1) and 30 parts by mass of the above component (B-2) was used, a film-producing apparatus equipped with a metallic matte textured roll with an arithmetic mean roughness (Ra) of 0.5 μm was used instead of a smooth roll (mirror-finished metal roll) as the first roll 4, and both sides of the obtained film were subjected to a corona surface treatment. The blocking resistance of the produced film was measured using the measurement method (3) in (vii) above. That is, film production and physical property measurements were performed in the same manner as in Example 30, except that a metallic matte textured roll with an arithmetic mean roughness (Ra) of 0.5 μm was used instead of a smooth roll (mirror-finished metal roll) as the first roll 4. The results are shown in Table 6.

[0114] Example 32 A film was produced in the same manner as in Example 1, except that only the above-mentioned component (A-1) was used as the resin (no mixture with component (B) was used), and a film-producing apparatus equipped with a metal matte texture roll with an arithmetic mean roughness (Ra) of 0.5 μm was used instead of a smooth roll (mirror-finished metal roll) as the first roll 4. The blocking resistance of the produced film was measured using the measurement method (3) in (vii) above. The results are shown in Table 6.

[0115] Example 33 A film was produced in the same manner as in Example 1, except that only the above-mentioned component (B-1) was used as the resin (not a mixture with component (A)) and that both sides of the obtained film were subjected to a corona surface treatment. The blocking resistance of the produced film was measured by the measurement method (3) in (vii) above. The results are shown in Table 6. In Table 6, for Examples 24 to 33, the cases where only one side of the film was subjected to the matte surface treatment are represented as "one side," and the cases where both sides of the film were subjected to the matte surface treatment are represented as "both sides."

[0116] [Table 6]

[0117] The results shown in Table 6 further confirm that applying a matte surface treatment to both sides of the film suppressed blocking more effectively than applying a matte surface treatment to only one side (similar to Table 5). These results also show that applying a matte surface treatment to both sides of the film effectively suppressed blocking, even when both sides were corona-treated.

[0118] Relationship between the mass fraction of amorphous polypropylene region and film flexibility Example 34 A film was produced in the same manner as in Example 1, except that a resin mixture of 70 parts by mass of the component (A-1) and 30 parts by mass of the component (B-5) was used in the same manner as in Example 24. The film was then subjected to the (v) tensile test to measure (v-1) the tensile modulus, (v-2) the stress difference (Δσ), and (v-3) the 5% strain tensile stress and the 100% strain tensile stress. The results are shown in Table 7.

[0119] Examples 35-41 Films were produced in the same manner as in Example 34, except that the types and amounts of components (A) and (B) were changed as shown in Table 7. The films were then subjected to the above-mentioned (v) tensile test to measure (v-1) tensile modulus, (v-2) stress difference (Δσ), and (v-3) 5% strain tensile stress and 100% strain tensile stress. The results are shown in Table 7.

[0120] [Table 7]

[0121] From the results shown in Table 7, it was found that the greater the mass ratio of the amorphous polypropylene region in the random copolymer as component (B) relative to the total mass of components (A) and (B) contained in the base film for dicing film (in this example, equal to the mass ratio of the amorphous polypropylene region relative to the total mass of the base film for dicing film), the better the flexibility of the film. [Explanation of symbols]

[0122] 1: Extruder 2:T die 3: Melting film 4: First roll 5: Second roll 6: Rotating roll 7: Film

Claims

1. A substrate film for a dicing film, (A) crystalline polypropylene and (B) polyolefin elastomer; The polyolefin elastomer (B) comprises at least one copolymer formed from at least two copolymerizable monomers containing at least two α-olefins other than ethylene selected from linear α-olefins and / or branched α-olefins, the melting enthalpy of the polyolefin elastomer (B) is more than 0 J / g and not more than 15 J / g, or 25 J / g or more and 40 J / g or less; The substrate film for dicing film satisfies the following properties (i) to (iv): (i) Internal haze is 20% or less; (ii) the gloss on at least one side is 40% or less; (iii) a melting point of 150°C or higher; (iv) The melting enthalpy is 30 to 90 J / g.

2. A substrate film for a dicing film as described in claim 1, wherein when the melting enthalpy of the (B) polyolefin-based elastomer is greater than 0 J / g and less than or equal to 15 J / g, the (B) polyolefin-based elastomer comprises a copolymer of 4-methyl-1-pentene and one or more other α-olefins.

3. A substrate film for a dicing film as described in claim 1, wherein when the melting enthalpy of the (B) polyolefin-based elastomer is 25 J / g or more and 40 J / g or less, the (B) polyolefin-based elastomer comprises a random copolymer composed of propylene and butene-1.

4. The substrate film for dicing film according to any one of claims 1 to 3, wherein the gloss of each of both surfaces is 40% or less.

5. The substrate film for dicing film according to any one of claims 1 to 4, further satisfying the following properties (v-1) and (v-2): (v-1) The tensile modulus in the machine direction is 600 MPa or less; (v-2) The difference between the tensile yield stress and the tensile lower yield stress in the machine direction is 2.5 MPa or less.

6. The substrate film for dicing film according to claim 3, wherein the mass ratio of the crystalline polypropylene region to the amorphous polypropylene region in the random copolymer is within a range of 40:60 to 60:

40.

7. 7. The substrate film for dicing film according to claim 3 or 6, wherein the mass ratio of the amorphous polypropylene region in the random copolymer to the total mass of the (A) crystalline polypropylene and the (B) random copolymer polyolefin elastomer is 10% or more.

8. A dicing film comprising a substrate film for a dicing film described in any one of claims 1 to 7.

9. A method for producing a substrate film for a dicing film according to any one of claims 1 to 7, comprising: (1) A step of continuously extruding a molten film from a T-die using an extrusion device equipped with an extruder and a T-die; (2) supplying and inserting the molten film between a first roll which is a rotating smooth roll or a textured roll and a second roll which is a rotating textured roll, and pressing the molten film between the first roll and the second roll; and (3) A step of wrapping the pressed film in the above step (2) around the first roll and sending it to the next rotating roll. A method comprising:

10. The method according to claim 9, wherein the grain roll is a matte rubber roll or a matte metal roll.

11. 11. The method according to claim 9 or 10, wherein the smooth roll is a mirror-finished metal roll.

12. A method for producing a dicing film according to claim 8, comprising: (1) A step of forming a substrate film for a dicing film by the method according to any one of claims 9 to 11; and (2) A step of forming a pressure-sensitive adhesive layer on the surface of the substrate film for dicing film obtained in the above step (1) having a gloss of 40% or less. A method comprising:

13. A method for producing a dicing film according to claim 8, comprising: (1) A step of forming a substrate film for a dicing film by the method according to any one of claims 9 to 11; and (2) If there is a surface of the substrate film for dicing film obtained in the above step (1) having a gloss of 50% or more, a step of forming a pressure-sensitive adhesive layer on that surface. A method comprising:

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