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

Abstract

The present invention addresses the problem of providing: a substrate film which is for a dicing film, has sufficient flexibility and transparency, and has excellent blocking resistance; a dicing film using the same; and methods for producing the substrate film and the dicing film. The present invention that addresses the problem is a substrate film for a dicing film, which includes (A) a crystalline polypropylene, and (B) a polyolefin-based elastomer, and satisfies characteristics (i)-(iv): (i) internal haze is at most 20%; (ii) the gloss on at least one side is at most 40%; (iii) the melting point is at least 150°C; (iv) the enthalpy of fusion is 30-90 J / g. The gloss on each of both sides may be at most 40%. In addition, the requirements below may be satisfied: (v-1) the tensile elastic modulus in a machine direction is at most 600 MPa; (v-2) the difference between a tensile yield stress and the tensile lower yield stress in the machine direction is 2.5 MPa.

Description

Technical Field

[0001] The present invention relates to a base film of an adhesive film (hereinafter referred to as a "dicing film") that is used by being bonded to the front surface and / or back surface of a silicon wafer or the like for the purpose of surface protection or the like when dicing (cutting and separating) the silicon wafer or the like, a dicing film using the same, and a method for manufacturing these.

Background Art

[0002] Semiconductor chips are produced by forming a large number of them on a large-diameter silicon wafer and then dicing them into individual semiconductor chips. The dicing process is often carried out after bonding a dicing film onto the front surface and / or back surface of a silicon wafer (on which a large number of semiconductor chips are formed) for the purpose of surface protection of the semiconductor chips, fixing and picking up the cut individual semiconductor chips, etc.

[0003] Particularly, in the expand process and the pick-up process, if the flexibility of the dicing tape is insufficient, the dicing tape may come off from the ring frame; the dicing tape may break; the interval between the cut wafers is narrow and the pick-up yield decreases; the chips may scatter and be damaged due to the load on the semiconductor wafer. Therefore, high flexibility is required for the base film for the dicing film.

[0004] Conventionally, the base film of a dicing film has many advantages such as a high balance between heat resistance and flexibility; having tensile properties suitable for the expansion process; high transparency; and low cost. Therefore, films of soft polyvinyl chloride resin compositions have been frequently used. On the other hand, since a large amount of plasticizer is blended in the film of the soft polyvinyl chloride resin composition, the plasticizer may migrate to the adhesive, making the adhesive properties unstable (decreasing or increasing the adhesive strength); there is also the disadvantage that the plasticizer may contaminate semiconductor chips and the like. Therefore, films of polypropylene resins or polypropylene resin compositions have been proposed as the base film of the dicing film (see, for example, Patent Documents 1 to 3). However, these performances as the base film of the dicing film are not as good as those of the film of the soft polyvinyl chloride resin composition. In addition, there is also the disadvantage that when sufficient flexibility and transparency are imparted to the film of the polypropylene resin or polypropylene resin composition as the base film of the dicing film, the antiblocking property becomes insufficient. A base film for a dicing film having sufficient flexibility and transparency and excellent antiblocking property is required, but such a base film has not been developed so far.

[0005] Incidentally, a dicing film generally includes a base film for a dicing film and an adhesive layer formed on its surface. In order to improve the adhesion (anchoring property) between the base film for a dicing film and the adhesive layer, corona discharge treatment is often performed by irradiating corona discharge energy on the adhesive layer forming surface of the base film for a dicing film. However, there is the disadvantage that blocking is likely to occur because stickiness occurs on the film treatment surface by performing the corona discharge treatment. In practical use, the corona discharge treatment may be applied to one side of the film or both sides of the film, but in either case, the disadvantage that blocking is likely to occur by performing the corona discharge treatment can occur. A base film for a dicing film that has the above-described required characteristics and can effectively prevent blocking, particularly even when subjected to corona discharge treatment (hereinafter, also simply referred to as "corona surface treatment") on the surface, is desirable. However, such a base film has not been developed to date.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0007] One problem of the present invention is to provide a base film suitable for a dicing film that can replace a film of a soft polyvinyl chloride resin composition, has sufficient flexibility and transparency, and is excellent in blocking resistance, and a dicing film using the same, and manufacturing methods thereof. Another problem of the present invention is to provide a base film suitable for a dicing film that can replace a film of a soft polyvinyl chloride resin composition, has sufficient flexibility and transparency, is excellent in blocking resistance, and can effectively prevent blocking particularly even when subjected to corona surface treatment, and a dicing film using the same, and manufacturing methods thereof.

Means for Solving the Problems

[0008] As a result of intensive research, the inventor of the present invention has found that the above problems can be solved by a specific resin film.

[0009] That is, aspects of the present invention are as follows. [1]. A base film for a dicing film, comprising: (A) crystalline polypropylene and (B) a polyolefin-based elastomer; The base film for a dicing film satisfying the following characteristics (i) to (iv): (i) The internal haze is 20% or less; (ii) The gloss of at least one surface is 40% or less; (iii) The melting point is 150°C or higher; (iv) The melting enthalpy is 30 to 90 J / g. [2]. The base film for a dicing film according to item [1] above, wherein the gloss of both surfaces is 40% or less, respectively. [3]. The base film for a dicing film according to item [1] or [2] above, further satisfying the following characteristics (v-1) and (v-2): (v-1) The tensile elastic 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]. (B) The polyolefin-based elastomer is a random copolymer composed of propylene and butene-1, and the base film for a dicing film according to item [1] or [2] above. [5]. The base film for a dicing film according to item [4] above, wherein the mass ratio of the crystalline polypropylene region and the amorphous polypropylene region in the random copolymer is in the range of 40:60 to 60:40. [6]. 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-based elastomer is 10% or more, and the base film for a dicing film according to the above item [4] or [5]. [7]. A dicing film including the base film for a dicing film according to any one of the above items [1] to [6]. [8]. A method for forming a base film for a dicing film according to any one of the above items [1] to [6], comprising: (1) A step of continuously extruding a molten film from a T-die using an extrusion device including an extruder and a T-die; (2) A step of feeding and introducing 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 with the first roll and the second roll; and (3) A step of feeding the film pressed in the step (2) while holding it by the first roll to the next rotating roll. The method including the above steps. [9]. The method according to the above item [8], wherein the textured roll is a grained rubber roll or a grained metal roll.

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

[11] . A method for manufacturing the dicing film according to the above item [7], comprising: (1) A step of forming a base 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 an adhesive layer on the surface of the base film for a dicing film obtained in the step (1) having a gloss of 40% or less. The method including the above steps.

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

[10] ; and, (2) When there is a surface with a gloss of 50% or more on the base film for a dicing film obtained in the above step (1), a step of forming an adhesive layer on that surface A method comprising.

Advantages of the Invention

[0010] In the film of the present invention, the problems caused by the plasticizer in the film of the soft polyvinyl chloride resin composition are fundamentally solved by not blending the plasticizer. Further, the film of the present invention is excellent in flexibility, transparency, and antiblocking property. A preferred film of the present invention is further excellent in heat resistance, flexibility, transparency, solvent resistance, and antiblocking property, and has tensile properties suitable for the expansion process. Due to the excellent flexibility of the base film for the dicing film, and thus the excellent flexibility of the dicing film, in the expansion process and the pickup process, the dicing tape comes off the ring frame; the dicing tape breaks; the interval between the cut wafers is narrow and the pickup yield drops; chips scatter and break due to the load on the semiconductor wafer, and the occurrence of such problems can be effectively suppressed. A more preferred film of the present invention is excellent in antiblocking particularly even when subjected to corona surface treatment. Therefore, the film of the present invention can be suitably used as a base film for a dicing film. The film of the present invention can be suitably produced by the production method of the present invention.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0012] In this specification, the term "resin" is used as a term that includes a resin mixture containing two or more resins and a resin composition containing components other than the resin. In this specification, the term "film" is used interchangeably or replaceably with "sheet". In this specification, the terms "film" and "sheet" are used for those that can be industrially wound into a roll. The term "plate" is used for those that cannot be industrially wound into a roll. Also, in this specification, laminating one layer on top of another layer in order includes both directly laminating those layers and laminating with one or more other layers such as an anchor coat intervening between those layers.

[0013] In this specification, the term "or more" related to a numerical range is used to mean a certain numerical value or more than a certain numerical value. For example, "20% or more" means 20% or more than 20%. The term "or less" related to a numerical range is used to mean a certain numerical value or less than a certain numerical value. For example, "20% or less" means 20% or less than 20%. The symbol "~" related to a numerical range is used to mean 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 numerical value larger than a certain numerical value. For example, "10~90%" means 10%, more than 10% and less than 90%, or 90%. Furthermore, the upper limit and the lower limit of the numerical range can be arbitrarily combined, and arbitrarily combined embodiments should be construed as being readable. For example, from the description such as "usually 10% or more, preferably 20% or more. On the other hand, usually 40% or less, preferably 30% or less." or "usually 10~40%, preferably 20~30%" related to the numerical range of a certain characteristic, it should be construed that a certain characteristic is 10~40%, 20~30%, 10~30%, or 20~40% in one embodiment.

[0014] Unless otherwise specified or except in the examples, all numerical values used in this specification and the claims should be understood to be modified by the term "about". Without intending to limit the application of the doctrine of equivalents to the claims, each numerical value should be construed in light of the significant figures and by applying ordinary rounding methods.

[0015] 1. Substrate film for dicing film The base film for the dicing film of the present invention has (i) an internal haze that is usually 20% or less, preferably 15% or less, more preferably 12% or less, and still more preferably 10% or less. By having the above (i) internal haze usually 20% or less, the transparency required for the dicing film, for example, the visibility during laser marking can be sufficiently ensured. The lower limit of the above (i) internal haze is not particularly limited from the viewpoint of transparency, and the lower the better.

[0016] In this specification, for the above (i) internal haze, two glass plates with paraffin oil applied on one surface of a smooth glass plate are prepared; next, the samples are sandwiched between the paraffin oil-coated surfaces of the two glass plates to form a measurement piece; subsequently, it is the haze measured 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 base film for a dicing film of the present invention has (ii) a gloss of usually 40% or less on at least one surface. Here, the gloss is the 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 base film for a dicing film of the present invention with the gloss adjusted to 40% or less may be referred to as a "matte surface". Also in the industry, the "matte surface" may sometimes be referred to as a "mat surface" or a "mat-treated surface". Since the gloss of the matte surface of the base film for a dicing film of the present invention is usually 40% or less, sufficient flexibility can be imparted as a base film for a dicing film and sufficient antiblocking properties can be exhibited. Also, by forming an adhesive layer on the matte surface, the external haze caused by the unevenness of the matte surface is canceled, and sufficient transparency as a dicing film is ensured. Furthermore, since the matte surface has large unevenness, by forming an adhesive layer on the matte surface, the effect of improving the adhesive strength between the base film for a dicing film of the present invention and the adhesive layer can be obtained. From the viewpoint of antiblocking properties, the gloss of at least one surface (matte surface) of the base film for a dicing film is preferably 35% or less, more preferably 30% or less, still more preferably 25% or less, even more preferably 20% or less, still more preferably 15% or less, further preferably 10% or less, and most preferably 6% or less. On the other hand, from the viewpoint of smoothing the surface of the adhesive layer, the gloss of at least one surface (matte surface) of the base film for a dicing film may preferably be 1% or more.

[0018] The arithmetic mean roughness (Ra) of the matte surface of the base film for a dicing film of the present invention is usually 0.5 to 10 μm, preferably 1 to 5 μm, from the viewpoints of antiblocking property and smoothing the surface of the adhesive layer. In this specification, the arithmetic mean roughness (Ra) is measured in accordance with JIS B0601:2013. More specifically, the arithmetic mean roughness (Ra) in this specification can be measured by the method described in the examples below.

[0019] In one aspect, the base film for a dicing film of the present invention may have a gloss of usually 40% or less on one surface and a gloss of usually 50% or more on the other surface. Hereinafter, the surface of the base film for a dicing film of the present invention whose gloss is adjusted to 50% or more may be referred to as a "glossy surface". Since the gloss of the glossy surface is usually 50% or more, sufficient transparency as a base film for a dicing film is ensured. The gloss of the glossy surface of the base film for a dicing film is usually 50% or more, preferably 55% or more, more preferably 60% or more, even more preferably 65% or more, still more preferably 70% or more, further more preferably 75% or more, even further more preferably 80% or more, and most preferably 85% or more, from the viewpoint of transparency. On the other hand, the gloss of the glossy surface of the base film for a dicing film may be preferably 140% or less, more preferably 130% or less, from the viewpoint of antiblocking property.

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

[0021] The base film for dicing film of the present invention has a melting point (iii) of usually 150°C or higher, preferably 155°C or higher, more preferably 160°C or higher. By having the melting point (iii) of 150°C or higher, the heat resistance required for the dicing film can be sufficiently ensured. Also, the solvent resistance required when forming an adhesive layer on the surface (usually the matte surface) of the base film for dicing film of the present invention can be sufficiently ensured. The melting point (iii) is preferably higher from the viewpoints of heat resistance and solvent resistance.

[0022] The base film for a dicing film of the present invention has an enthalpy of fusion (iv) 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, for the base film for a dicing film of the present invention, the enthalpy of fusion (iv) is usually 90 J / g or less, preferably 85 J / g or less, more preferably 80 J / g or less, still more preferably 75 J / g or less, and even more preferably 70 J / g or less from the viewpoint of flexibility.

[0023] In this specification, the above (iii) melting point and the above (iv) enthalpy of fusion are measured from the DSC first melting curve calculated according to JIS K7121-1987, using a differential scanning calorimeter (DSC measuring device), after holding at 25°C for 5 minutes and then heating at a rate of 10°C / min to 190°C. At this time, the above (iii) melting point is the peak top temperature of the melting peak appearing in the above DSC first melting curve. When two or more melting peaks are observed, the peak top temperature of the melting peak with the maximum peak top height is taken as the above (iii) melting point. Fig. 1 shows a DSC measurement example of Example 1. The lowermost curve in Fig. 1 is the DSC first melting curve, the uppermost curve is the DSC crystallization curve, and the middle curve is the DSC second melting curve. It should be noted that for the melting peak appearing in the DSC first melting curve of the crystalline polypropylene-based resin composition, usually, the trailing edge on the low temperature side extends gently and long; and the baseline should be drawn so that the straight line obtained by extending the high temperature side baseline in Fig. 1 of the reading method of the DTA or DSC curve in JIS K7121-1987 to the low temperature side coincides with the straight line obtained by extending the low temperature side baseline to the high temperature side. More specifically, the melting point and the enthalpy of fusion in this specification can be measured by the method described in the examples below.

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

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

[0026] The ratio of the tensile elastic modulus MD to the tensile elastic modulus TD (tensile elastic modulus MD / tensile elastic modulus TD) of the base film for dicing film of the present invention is usually 0.5 to 1.5, preferably 0.7 to 1.5, more preferably 0.8 to 1.5, and still more preferably 0.8 to 1.2 from the viewpoint of uniformly stretching the film in the expand process following the dicing process.

[0027] In this specification, the tensile elastic modulus MD complies with JIS K7127:1999. Using a test piece punched out from the film into the shape of test piece type 5 (Figure 2 of the said JIS standard) in accordance with the said standard, with the machine direction of the film being the tensile direction, a stress-strain curve (hereinafter abbreviated as "SS curve") obtained by conducting a tensile test under the conditions of a tensile speed of 200 mm / min and a temperature of 23°C, regardless of the provisions for calculation and result display in Article 10 of JIS K7127:1999, it is calculated by a method based on the slope obtained from two points in Article 10.3.2 of JIS K7161-1:2014. Also, regardless of the provisions in Article 10.3.2 of JIS K7161-1:2014, σ1 is the stress (MPa) at a strain ε1 = 0.8%, and σ2 is the stress (MPa) at a strain ε2 = 1.6%. The tensile elastic modulus TD is measured and calculated in the same manner except that the test piece is punched out with the transverse direction of the film being the tensile direction. More specifically, the tensile elastic modulus MD and the tensile elastic modulus TD in this specification can be measured by the method described in the examples below.

[0028] The stress difference (Δσ) between the tensile yield stress (σy) and the tensile descending yield stress (the stress at the point (ε1) where the tensile stress, which had decreased with the increase in tensile strain after the tensile strain exceeded the tensile yield strain (εy), turned to increase again) (σ1) of the base film for dicing film of the present invention, measured under the condition that the machine direction is the tensile direction, from the perspective of the suitability for the expand process of dicing, may usually be 3 MPa or less, preferably 2.5 MPa or less, more preferably 2 MPa or less, even more preferably 1 MPa or less, and still more preferably 0.5 MPa or less. The stress difference MD is preferably smaller from the perspective of expandability.

[0029] For the base film for dicing film of the present invention, the stress difference (Δσ) between the tensile yield stress (σy) and the tensile lower yield stress (σ1) measured under the condition that the lateral direction (the direction perpendicular to the machine direction) is the tensile direction (hereinafter abbreviated as "stress difference TD") may usually be 3 MPa or less, preferably 2 MPa or less, more preferably 1 MPa or less, and still more preferably 0.5 MPa or less from the viewpoint of suitability for the expand step of dicing. The stress difference TD is preferably smaller from the viewpoint of expandability.

[0030] In this specification, the stress difference MD is in accordance with JIS K7127:1999. Using a test piece punched out from the film into the shape of test piece type 5 (Figure 2 of this JIS standard) such that the machine direction of the film is the tensile direction, a tensile test is conducted under the conditions of a tensile speed of 200 mm / min and a temperature of 23°C. From the SS curve obtained, in accordance with Section 10.1 of JIS K7161-1:2014, the tensile yield stress (σy) is taken as the stress at the tensile yield strain (εy) (paying attention to Appendix A of this JIS standard at this time), and the tensile lower yield stress (σ1) is obtained and 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 is measured and calculated in the same manner except that the test piece is punched out such that the lateral direction of the film is 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 described later.

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

[0032] The base film for dicing film of the present invention contains (A) crystalline polypropylene and (B) a polyolefin-based elastomer. Hereinafter, each component will be described.

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

[0034] The above component (A) crystalline polypropylene mainly contains structural units derived from propylene and is a resin having high crystallinity. Here, "mainly containing 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, still more preferably 80 mol% or more, and typically 90 to 100 mol%. "Having high crystallinity" for the component (A) crystalline polypropylene means that the melting enthalpy (the measurement method will be described later) is usually 50 J / g or more. In one aspect, the melting enthalpy of the component (A) crystalline polypropylene may be preferably 60 J / g or more, more preferably 65 J / g or more, still more preferably 70 J / g or more.

[0035] In the case of isotactic polypropylene for the above component (A) crystalline polypropylene, the meso diad fraction (the ratio of the steric structure of the structural units derived from two consecutive propylenes having an isotactic structure) is 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, the racemic diad fraction (the ratio of the steric structure of the structural units derived from two consecutive propylenes having a syndiotactic structure) is usually 80 mol% or more, preferably 90 mol% or more, more preferably 95 mol% or more, and typically 97 to 100 mol%.

[0036] Examples of the above component (A) crystalline polypropylene include, for example, propylene homopolymer; copolymers of propylene and one or more of other small amounts of α-olefins (for example, ethylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene, etc.) (including block copolymers and random copolymers). Here, such a block copolymer of propylene and other small amounts of α-olefins as component (A) may contain an amorphous region or an amorphous block in addition to the crystalline region or the crystalline block.

[0037] Among these, as the above component (A) crystalline polypropylene, from the viewpoint of making the melting point and melting enthalpy of the base film for dicing film within a specified range, and from the viewpoint of making the melting point and melting enthalpy of the above component (A) crystalline polypropylene within the preferable range described later, a block copolymer of propylene and one or more of other small amounts of α-olefins is preferable. As the above component (A) crystalline polypropylene, a mixture of one or more of these block copolymers can be used.

[0038] From the viewpoints of heat resistance and solvent resistance, the melting point of the above component (A) crystalline polypropylene may preferably be 150 °C or higher, more preferably 155 °C or higher, still more preferably 160 °C or higher. From the viewpoints of heat resistance and solvent resistance, a higher melting point is more preferable. Also, as the above component (A) crystalline polypropylene, from the viewpoints of heat resistance and solvent resistance, it is preferable that no peak with a peak top temperature of less than 150 °C, which is a sub-peak, appears in the following second melting curve.

[0039] The melting enthalpy of the above component (A), crystalline polypropylene, may usually be 50 J / g or more, more preferably 60 J / g or more, still more preferably 70 J / g or more, from the viewpoints of heat resistance and solvent resistance. On the other hand, the melting enthalpy of the above component (A) depends on the blending ratio of the above component (A), crystalline polypropylene, and the above component (B), polyolefin-based elastomer, and may preferably be 110 J / g or less, more preferably 100 J / g or less, from the viewpoint of flexibility.

[0040] In this specification, the melting point and melting enthalpy of the above component (A), crystalline polypropylene, are measured in accordance with JIS K7121-1987 using a differential scanning calorimeter (DSC measuring device). The sample is held at 190°C for 5 minutes, cooled to -10°C at a rate of 10°C / min, held at -10°C for 5 minutes, and then heated to 190°C at a rate of 10°C / min. The second melting curve (the melting curve measured during the last heating process) is used for calculation. At this time, the melting point is the peak top temperature of the melting peak appearing in the above second melting curve. When two or more melting peaks are observed, the peak top temperature of the melting peak with the maximum peak top height is taken as the melting point. 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. The melting peak appearing in the second melting curve of DSC for crystalline polypropylene usually has a gently long tail on the low-temperature side; and it should be noted that the baseline should be drawn so that the straight line obtained by extending the high-temperature side baseline in Figure 1 of the reading method of DTA or DSC curves in JIS K7121-1987 to the low-temperature side coincides with the straight line obtained by extending the low-temperature side baseline to the high-temperature side.

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

[0042] (B) Polyolefin-based elastomer The base film for a dicing film of the present invention contains the above component (B), a polyolefin-based elastomer. The above component (B), the polyolefin-based elastomer, makes the flexibility of the base film for a dicing film of the present invention excellent and functions to impart tensile properties suitable for the expansion process.

[0043] The above component (B), the polyolefin-based elastomer, is an elastomer mainly containing (usually 50 mol% or more, preferably 70 mol% or more, more preferably 90 mol% or more. Typically 95 to 100 mol%) structural units derived from α-olefins.

[0044] Here, the "elastomer" regarding the component (B), the polyolefin-based elastomer, means that the melting enthalpy (the measurement method will be described later) is usually 45 J / g or less. As one aspect, the melting enthalpy of the component (B), the polyolefin-based elastomer, may preferably be 15 J / g or less, more preferably 10 J / g or less, still more preferably 5 J / g or less, and most preferably 0 J / g (no melting peak is observed in the second melting curve of DSC). Also, in another aspect, the melting enthalpy of the component (B), the polyolefin-based elastomer, may preferably be in the range of 10 J / g or more and 20 J / g or less, and more preferably in the range of 10 J / g or more and 15 J / g or less. Also, in yet another aspect, the melting enthalpy of the component (B), the polyolefin-based elastomer, may preferably be 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 still 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 above-mentioned component (B) polyolefin-based elastomer are measured in accordance with JIS K7121-1987 using a differential scanning calorimeter (DSC measuring device). The sample is held at 190°C for 5 minutes, cooled to -50°C at a rate of 10°C / min, held at -50°C for 5 minutes, and then heated to 190°C at a rate of 10°C / min. The second melting curve (the melting curve measured during the last heating process) is used for calculation. At this time, the melting point is the peak top temperature of the melting peak appearing in the above-mentioned second melting curve. When two or more melting peaks are observed, the peak top temperature of the melting peak with the maximum peak top height is taken as the melting point. Also, it should be noted that the melting peak appearing in the second melting curve of the DSC of the elastomer usually has a gently extended tail on both the high-temperature side and the low-temperature side; and the baseline should be drawn so that the straight line obtained by extending the high-temperature side baseline in Figure 1 of the reading method of the DTA or DSC curve in JIS K7121-1987 to the low-temperature side coincides with the straight line obtained by extending the low-temperature side baseline to the high-temperature side. 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-olefin include linear α-olefins and α-olefins having a branched chain. Examples of the linear α-olefin 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 α-olefin having a branched chain 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, the α-olefin preferably has 2 to 8 carbon atoms. One or more of these can be used as the α-olefin.

[0047] The above component (B) polyolefin-based elastomer may contain a structural unit derived from a monomer copolymerizable with the above α-olefin in addition to the above α-olefin. Examples of the copolymerizable monomer 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 acid anhydrides such as maleic anhydride. One or more of these can be used as the copolymerizable monomer.

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

[0049] Among these, as the above component (B) polyolefin elastomer, from the viewpoint of the balance between flexibility and antiblocking property, copolymers of 4-methyl-1-pentene and one or more other α-olefins (sometimes referred to as "TPX-based elastomers" in the art) are preferred. Among such copolymers, those containing structural units derived from 4-methyl-1-pentene usually in an amount of 50 to 90 mol%, preferably 60 to 80 mol%, more preferably 65 to 75 mol% are more preferred. Here, the sum of all types of structural units is 100 mol%. The melting enthalpy of such a copolymer of 4-methyl-1-pentene and one or more other α-olefins is 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 second melting curve of DSC).

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

[0051] In other embodiments, from the viewpoint of the balance between flexibility and blocking resistance, the above-mentioned component (B) polyolefin elastomer is preferably a random copolymer composed of propylene and butene-1. The mass ratio of the crystalline polypropylene region to the amorphous polypropylene region in the random copolymer composed of propylene and butene-1 is estimated to usually vary within the range of 10:90 to 90:10, preferably 15:85 to 85:15, more preferably 20:80 to 80:20, still more preferably 25:75 to 75:25, and even more preferably 30:70 to 70:30. Thus, it is considered that a preferable balance between flexibility and blocking resistance can be obtained. From the viewpoint of obtaining such characteristics, the melting enthalpy of the random copolymer composed of propylene and butene-1 may preferably be in the range of 10 J / g or more and 20 J / g or less, and more preferably in the range of 10 J / g or more and 15 J / g or less. 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, still more preferably 45:55 to 55:45, and most preferably substantially 50:50 (for example, 48:52 to 52:48) from the viewpoint of the balance between flexibility and blocking resistance as described above, and further from the viewpoint of obtaining excellent blocking resistance even when the base film for dicing film is subjected to corona surface treatment. From the viewpoint of obtaining such characteristics, the melting enthalpy of the random copolymer composed of propylene and butene-1 may preferably be 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 still more preferably in the range of 30 J / g or more and 35 J / g or less.

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

[0053] The blending ratio of the above component (A) crystalline polypropylene and the above component (B) polyolefin-based elastomer may be appropriately determined in consideration of the melting enthalpy of the above component (A) crystalline polypropylene and the melting enthalpy of the above component (B) polyolefin-based elastomer from the viewpoint of making the melting enthalpy of the base film for dicing film of the present invention 30 to 90 J / g. Considering the discussion based on the examples described later, the melting enthalpy is almost additive. Therefore, for example, when it is desired to make the melting enthalpy of (iv) above 60 J / g, the blending amount b parts by mass of the above component (B) with respect to 100 parts by mass of the blending amount of the above component (A) can be determined by solving the following formula (1) for b. (100·ΔH A +b·ΔHB ) / (100 + b)=60 ···(1) Here, ΔH A is the enthalpy of fusion (J / g) of the above component (A), and ΔH B is the enthalpy of fusion (J / g) of the above component (B). When generalizing the desired enthalpy of fusion (iv) to ΔH, Equation (2) below may be solved for b. (100·ΔH A + b·ΔH B ) / (100 + b)=ΔH ···(2) Here, ΔH is the desired enthalpy of fusion (iv) (J / g), ΔH A is the enthalpy of fusion (J / g) of the above component (A), and ΔH B is the enthalpy of fusion (J / g) of the above component (B).

[0054] As demonstrated in the examples described below, the greater the mass ratio of the amorphous polypropylene region in the random copolymer as component (B) 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 to the total mass of the base film for dicing film), the more excellent the flexibility of the film tends to be.

[0055] Note that the base film for dicing film of the present invention may contain any optional component(s) (single or plural types) known in the art other than the above components (A) and (B). The ratio of such an optional component is not particularly limited, but may be, for example, 5% by mass or less based on the total mass of the constituent components of the film. Preferably, the plasticizer is not included in such optional components.

[0056] 2. Film formation method The method for forming the base film for dicing film of the present invention is not particularly limited, and the film can be formed by any method. As a preferred method for forming the base film for dicing film of the present invention, for example, (1) A step of using an extrusion device including an extruder and a T-die to continuously extrude a molten film from the T-die; (2) A step of feeding the molten film between a first roll which is a rotating smooth roll or embossed roll and a second roll which is a rotating embossed roll, and pressing the molten film with the first roll and the second roll (when both sides are to be "mat surfaces" ("mat-treated surfaces"), an embossed roll is used as the first roll); and, (3) A step of holding the film pressed in the step (2) by the first roll and feeding it to the next rotating roll A method including the above steps can be mentioned.

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

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

[0059] The T-die used in the step (1) is not particularly limited, and any T-die can be used. Examples of the T-die include a manifold die, a fish-tail die, and a coat-hanger die.

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

[0061] The above-mentioned smoothing roll (when used) used in the above-mentioned step (2) is appropriately selected from the viewpoint of making the gloss of the glossy surface of the base film for dicing film of the present invention 50% or more. The above-mentioned smoothing roll preferably makes the gloss of one surface of the base film for dicing film of the present invention 55% or more, more preferably 60% or more, even more preferably 65% or more, still more preferably 70% or more, further preferably 75% or more, even further preferably 80% or more, and most preferably 85% or more. From this viewpoint, it is preferably a mirror roll.

[0062] The above-mentioned mirror roll is a roll whose surface is mirror-finished. Examples of the above-mentioned mirror roll include a mirror roll whose surface is made of metal, ceramic, or rubber. The surface of the above-mentioned mirror roll can be subjected to chrome plating, iron-phosphorus alloy plating, hard carbon treatment by PVD method or CVD method, etc. for the purpose of protecting against corrosion and damage.

[0063] The above-mentioned mirror finishing is not limited and can be performed by any method. The above-mentioned mirror finishing includes, for example, a method of polishing using fine abrasive grains to make the arithmetic mean roughness (Ra) of the surface of the above-mentioned mirror 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 smoothing roll (if used) used in the above step (2) functions as a cooling roll. From the perspective of ensuring that the film is completely cooled and solidified when the film is sent to the next rotating roll in the above step (3), the smoothing roll is preferably a metal roll. From the perspective of making the gloss of the glossy surface of the base film for dicing film of the present invention 50% or more, and from the perspective of ensuring that the film is completely cooled and solidified when the film is sent to the next rotating roll in the above step (3), the smoothing roll is more preferably a mirror-finish metal roll.

[0066] The surface temperature of the smoothing roll (if used) used in the above step (2) is appropriately selected from the perspective of making the gloss of the glossy surface of the base film for dicing film of the present invention 50% or more, from the perspective of ensuring that the film is completely cooled and solidified when the film is sent to the next rotating roll in the above step (3), and from the perspective of preventing dew condensation on the surface of the smoothing roll. From the perspective of increasing the gloss of the glossy surface to 50% or more by increasing the degree of supercooling (the temperature difference between the surface temperature of the smoothing roll and the temperature of the molten film immediately before contacting the smoothing roll), and from the perspective of ensuring that the film is completely cooled and solidified when the film is sent to the next rotating roll in the above step (3), the surface temperature of the smoothing roll is usually 80°C or lower, preferably 60°C or lower, more preferably 50°C or lower. On the other hand, from the perspective of preventing dew condensation on the surface of the smoothing roll, although it depends on the temperature and humidity of the film-forming environment, the surface temperature of the smoothing roll is usually 15°C or higher, preferably 20°C or higher, more preferably 25°C or higher.

[0067] The embossed roll used in the above step (2) is appropriately selected from the viewpoint of making the gloss of the matte surface of the base film for the dicing film of the present invention 40% or less. The embossed roll is a roll whose surface is embossed, and is typically a roll with a satin finish (satin roll). Examples of the embossed roll include an embossed roll whose surface is made of metal, ceramic, or rubber. When the embossed roll is used as the second roll, from the viewpoints of low thermal conductivity (cooling efficiency) and ease of reducing gloss, and ease of film-forming work (for example, difficulty of causing troubles that damage the smooth roll), an embossed roll whose surface is made of rubber is preferable. The embossed roll when used as the second roll is more preferably a satin rubber roll from the above viewpoints. On the other hand, when the embossed roll is used as the first roll, it may preferably be made of metal, and typically may be a satin metal roll, from the viewpoint of ensuring that the film is completely cooled and solidified when the film is sent to the next rotating roll in the above step (3).

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

[0069] The surface temperature of the embossing roll used in the above step (2) is appropriately selected from the viewpoints of reducing the gloss of the matte surface of the base film for the dicing film of the present invention to 40% or less, suppressing and preventing troubles such as the adhesion of the molten film to the embossing roll, and preventing dew condensation on the surface of the embossing roll. From the viewpoint of suppressing and preventing troubles such as the adhesion of the molten film to the embossing roll, the surface temperature of the embossing roll is usually 80°C or lower, preferably 70°C or lower, more preferably 60°C or lower. On the other hand, from the viewpoints of reducing the gloss of the matte surface of the base film for the dicing film of the present invention to 40% or less and preventing dew condensation on the surface of the embossing roll, although it depends on the material of the surface of the embossing roll and the temperature and humidity of the film-forming environment, the surface temperature of the embossing roll is usually 15°C or higher, preferably 30°C or higher, more preferably 40°C or higher. In one embodiment, in step (2), cooling water may be applied to the embossing roll as necessary.

[0070] The above step (3) is a step of holding the film pressed in the above step (2) by the first roll and feeding it to the next rotating roll. By holding the molten film by the first roll, it becomes easier to ensure that the molten film is completely cooled and solidified when being fed to the next rotating roll.

[0071] FIG. 5 is a conceptual diagram of a film-forming apparatus of one embodiment used in the examples (when producing a base film for a dicing film where one side is a matte surface (matte-treated surface) and the other side is a glossy surface). The raw material resin becomes a molten film 3 by an extrusion device including an extruder 1 and a T-die 2 and is continuously extruded from the T-die 2. Next, the extruded molten film 3 is fed between a rotating first roll (in this case, a smooth roll) 4 and a rotating second roll (embossing roll) 5 and is pressed by the first roll 4 and the second roll 5. Then, when the pressed molten film 3 is held by the first roll 4 and fed to the next rotating roll 6, it becomes a completely cooled and solidified film 7.

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

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

[0074] As the adhesive for forming the above adhesive layer, an adhesive having excellent transparency is preferable from the viewpoint of sufficiently ensuring the transparency required for the dicing film, for example, the visibility during laser marking. Here, the "adhesive having excellent transparency" means an adhesive having a visible light transmittance of usually 50% or more, preferably 70% or more, more preferably 80% or more, and still more preferably 85% or more. Here, the visible light transmittance can be calculated as the ratio of the integrated area of the transmittance spectrum of the adhesive measured using the spectrophotometer "Solid Spec-3700" (trade name) of Shimadzu Corporation and a quartz cell with an optical path length of 10 mm in the wavelength range of 380 to 780 nanometers to the integrated area of the transmittance spectrum assuming that the transmittance in the entire wavelength range of 380 to 780 nanometers is 100%.

[0075] As the adhesive for forming the adhesive layer, an adhesive capable of reducing the adhesive strength by thermosetting or active energy ray curing is also preferable. By reducing the adhesive strength, when peeling the dicing film from the workpiece, there will be no adhesive residue and it can be easily peeled off cleanly. Examples of the adhesive capable of reducing the adhesive strength by thermosetting or active energy ray curing include, for example, an adhesive having two or more reactive functional groups (such as amino group, vinyl group, epoxy group, methacryloxy group, acryloxy group, and isocyanate group, etc.) in one molecule; an adhesive composition of the adhesive and at least one or more of an isocyanate-based curing agent, a photopolymerization initiator, and an organic peroxide, etc.

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

Examples

[0077] Measurement method (i) Haze inside Two sheets of float glass (2 mm thick) specified in JIS R3202:2011 with paraffin oil (「Moresco White P-350P」(trade name) of Moresco Corporation) applied on one surface were prepared. Next, the samples were sandwiched between the paraffin oil-coated surfaces of the two glass plates to form measurement pieces. Subsequently, the haze measured using a turbidimeter 「NDH2000」(trade name) of Nippon Denshoku Industries Co., Ltd. in accordance with JIS K7136:2000 was taken as the haze inside.

[0078] (ii) Gloss (60-degree gloss value) In accordance with JIS Z8741:1997, the gloss (60-degree gloss value) was measured using the multi-angle gloss meter "GM-268" (trade name) of Konica Minolta, Inc. The measurement was performed on both sides of the sample. In the table, the value of the side that was on the smooth roll (mirror-finish metal roll) side during film formation was entered in the column "Gloss of Glossy Surface", and the value of the other side (the side that was on the embossed roll (pebbled rubber roll) side) was entered in the column "Gloss of Matte Surface".

[0079] (iii) Melting point The method for measuring the melting point of the base film for dicing film is as follows. In accordance with JIS K7121-1987, using the differential scanning calorimeter "Diamond DSC" (trade name) of PerkinElmer, after holding at a temperature of 25°C for 5 minutes, the peak top temperature of the melting peak appearing in the DSC first melting curve measured with a temperature program of heating up to 190°C at a heating rate of 10°C / min was calculated as the melting point. When two or more melting peaks were observed, the peak top temperature of the melting peak with the maximum peak top height was taken as the melting point. Also, the peak top temperatures of the sub-peaks (melting peaks other than the melting peak with the maximum peak top height) were entered in the column of sub-peaks in the table. The fact that the column of sub-peaks in the table is "-" means that no sub-peaks were observed (there was only one melting peak). In addition, the melting point of the above component (A), crystalline polypropylene, is measured in accordance with JIS K7121-1987 using the differential scanning calorimeter "Diamond DSC" (trade name) of PerkinElmer. It is held at 190°C for 5 minutes, cooled to -10°C at a rate of 10°C / min, held at -10°C for 5 minutes, and then heated to 190°C at a rate of 10°C / min. The melting point is calculated from the second melting curve (the melting curve measured during the last heating process). At this time, the melting point is the peak top temperature of the melting peak appearing in the above second melting curve. When two or more melting peaks are observed, the peak top temperature of the melting peak with the maximum peak top height is taken as the melting point. Regarding the melting peak appearing in the DSC second melting curve of crystalline polypropylene, usually, the trailing edge on the low temperature side gently extends for a long time; and it should be noted that the baseline should be drawn so that the straight line obtained by extending the high temperature side baseline described in Figure 1 of the reading method of 9.DTA or DSC curves in JIS K7121-1987 to the low temperature side coincides with the straight line obtained by extending the low temperature side baseline to the high temperature side. In addition, the melting point of the above component (B), polyolefin-based elastomer, is measured in accordance with JIS K7121-1987 using the differential scanning calorimeter "Diamond DSC" (trade name) of PerkinElmer. It is held at 190°C for 5 minutes, cooled to -50°C at a rate of 10°C / min, held at -50°C for 5 minutes, and then heated to 190°C at a rate of 10°C / min. The melting point is calculated from the second melting curve (the melting curve measured during the last heating process). At this time, the melting point is the peak top temperature of the melting peak appearing in the above second melting curve. When two or more melting peaks are observed, the peak top temperature of the melting peak with the maximum peak top height is taken as the melting point. Regarding the melting peak appearing in the DSC second melting curve of the elastomer, usually, the trailing edge extends gently and for a long time on both the high temperature side and the low temperature side; and it should be noted that the baseline should be drawn so that the straight line obtained by extending the high temperature side baseline described in Figure 1 of the reading method of 9.DTA or DSC curves in JIS K7121-1987 to the low temperature side coincides with the straight line obtained by extending the low temperature side baseline to the high temperature side.

[0080] (iv) Melting enthalpy Regarding the melting enthalpy of the base film for dicing film, it was calculated from the DSC first melting curve obtained in the above (iii) measurement of the melting point. Also, regarding the melting enthalpy of the above component (A) crystalline polypropylene and component (B) polyolefin-based elastomer, it was calculated from the DSC second melting curve obtained in the above (iii) measurement of the melting point.

[0081] (v) Tensile test In accordance with JIS K7127:1999, using the tensile tester "Autograph AGS-1kNG" (trade name) of Shimadzu Corporation, a sample was punched out from the film into the shape of test piece type 5 (Figure 2 of the JIS standard) of the above specifications so that the machine direction of the film was the tensile direction. A tensile test was conducted under the conditions of a tensile speed of 200 mm / min and a temperature of 23°C to obtain a stress-strain curve in the machine direction (hereinafter abbreviated as "SS curve"). In the same manner, except that the sample was punched out so that the transverse direction (the direction perpendicular to the machine direction) of the film was the tensile direction, a SS curve in the transverse direction was obtained.

[0082] (v-1) Tensile modulus Based on the slope obtained from two points in Section 10.3.2 of JIS K7161-1:2014, regardless of the provisions of Section 10 of the calculation and result display in JIS K7127:1999, from the SS curve in the machine direction obtained in the above (v) tensile test, the tensile modulus in the machine direction (described as "tensile modulus MD" in the table) was calculated with σ1 being the stress (MPa) at a strain ε1 = 0.8% and σ2 being the stress (MPa) at a strain ε2 = 1.6%. Similarly, from the SS curve in the transverse direction obtained in the above (v) tensile test, the tensile modulus in the transverse direction (described as "tensile modulus TD" in the table) was calculated. 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. Described 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 above (v) tensile test, in accordance with Clause 10.1 of JIS K7161-1:2014, the tensile yield stress (σy) was taken as the stress at the tensile yield strain (εy) (paying attention to Appendix A of this JIS standard at this time), the tensile lower yield stress (σ1) was taken as the stress at the strain (ε1), the tensile yield stress (σy) and the tensile lower yield stress (σ1) were calculated, and the stress difference in the machine direction (Δσ = σy - σ1) was calculated (described as "stress difference MD" in the table). From the transverse SS curve obtained in the above (v) tensile test, in the same manner, the stress difference in the transverse direction was calculated (described as "stress difference TD" in the table).

[0084] (v-3) Tensile stress at 5% strain, tensile stress at 100% strain From the machine direction SS curve obtained in the above (v) tensile test, in accordance with Clause 10.1 of JIS K7161-1:2014, the tensile stress at 5% strain in the machine direction (described as "5% modulus MD" in the table) and the tensile stress at 100% strain in the machine direction (described as "100% modulus MD" in the table) were calculated. From the transverse SS curve obtained in the above (v) tensile test, in the same manner, the tensile stress at 5% strain in the transverse direction (described as "5% modulus TD" in the table) and the tensile stress at 100% strain in the transverse direction (described as "100% modulus TD" in the table) were calculated. Furthermore, the ratio of the tensile stress at 5% strain in the machine direction to the tensile stress at 5% strain in the transverse direction (tensile stress at 5% strain in the machine direction / tensile stress at 5% strain in the transverse direction; described as "5% modulus MD / TD" in the table) was calculated. Similarly, the ratio of the tensile stress at 100% strain in the machine direction to the tensile stress at 100% strain in the transverse direction (tensile stress at 100% strain in the machine direction / tensile stress at 100% strain in the transverse direction; described as "100% modulus MD / TD" in the table) was calculated.

[0085] The ratio of the 5% elongation tensile stress in the machine direction to the 5% elongation tensile stress in the transverse direction is usually 0.7 to 1.3, preferably 0.8 to 1.2, more preferably 0.9 to 1.1, from the viewpoint of uniformly stretching the film in the expand process of dicing. The ratio of the 100% elongation tensile stress in the machine direction to the 100% elongation tensile stress in the transverse direction is usually 0.7 to 1.3, preferably 0.8 to 1.2, more preferably 0.9 to 1.1, from the viewpoint of uniformly stretching the film in the expand process of dicing.

[0086] (vi) Arithmetic mean roughness (Ra) of the matte surface In accordance with JIS B0601:2013, the arithmetic mean roughness (Ra) of the matte surface was measured using the roughness meter "HANDYSURF E-40A" (trade name) of Tokyo Seimitsu Co., Ltd.

[0087] (vii) Blocking resistance · Measuring method of blocking resistance (1) Two samples with a size of 30 cm in the machine direction and 10 cm in the transverse direction were taken from a film having a matte surface on one side and a glossy surface on the other side; the matte surface of one sample and the glossy surface of the other sample were overlapped so that each piece of the two samples substantially coincided; the two samples overlapped were sandwiched between two 30 cm × 10 cm metal plates and placed flat so that each piece of the two samples sandwiched between the two metal plates substantially coincided; a 1 kg weight was placed thereon and treated at 25 °C for 48 hours. Subsequently, the 90° peel strength of the two samples was measured under the condition that the test speed was 300 mm / min and the machine direction of the sample was parallel to the peel direction. In the table, "<0.1" means that the 90° peel strength was less than 0.1 N / 10 cm. From the viewpoint of blocking resistance, the above 90° peel strength is preferably 0.5 N / 10 cm or less, more preferably 0.3 N / cm or less. The smaller the above 90° peel strength, the better. · Measuring method of blocking resistance (2) Regarding a film having a matte surface on one side and a matte surface or a glossy surface on the other side, with corona surface treatment applied to both sides, the size of the sample was changed to 20 cm in the machine direction and 10 cm in the transverse direction. The matte surfaces were overlapped with each other or with the matte or glossy surface, the load by the weight was changed to 6 kg, the aging condition was changed to treatment at 80 °C for 5 hours, and the test speed was changed to 50 mm / min. Except for these changes, the 90° peel strength of both samples was measured by the same method as described above. · Measuring method for blocking resistance (3) Regarding a film having a matte surface on one side and a matte surface or a glossy surface on the other side, with or without corona surface treatment applied, while applying a tension of 2 kg, it was wound into a roll with a roll width of 10 inches (25.4 cm). After leaving it standing in an environment at 40 °C for one week, for this film wound into a roll, using a peel tester, the peel strength was measured when pulling out the film at a position 10 m in the longitudinal direction from the winding core in the longitudinal direction at a test speed of 200 mm / min.

[0088] (viii) Solvent resistance On the matte surface (the surface on the embossing roll side during film formation; for Example 2, the surface on the air chamber side), after dropping 3 drops of toluene using a dropper, it was left standing for 24 hours in an environment at a temperature of 25 °C and a relative humidity of 50% (the dropped toluene was dried). Subsequently, the gloss (60-degree gloss value) at the toluene dropping location was measured by the method of the above test (ii). The difference between the gloss at the toluene dropping location and the gloss of the matte surface (hereinafter sometimes referred to as "gloss difference"; gloss difference = gloss at the toluene dropping location - gloss of the matte surface) was calculated. When the solvent resistance is low, the gloss at the toluene dropping location decreases due to surface roughness or increases due to melting of surface irregularities. Therefore, from the perspective of solvent resistance, the above gloss difference may preferably be -3 to 3%, more preferably -2 to 2%, and still more preferably -1 to 1%. It is preferable that the absolute value of the above gloss difference is smaller.

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

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

[0091] Example 1 Using 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), a film-forming apparatus (an extrusion apparatus having an extruder 1 and a T-die 2, and a winding device having a mechanism for nipping between a smooth roll (mirror-finish metal roll) as the first roll 4 and a embossed roll (pebbled rubber roll: arithmetic mean roughness of the surface (Ra) 1.5 μm, ten-point mean roughness (Rz) 11.9 μm) as the second roll 5) shown in the conceptual diagram in Fig. 5 was used, and the above resin mixture was continuously extruded from the T-die 2 as a molten film 3. Next, the extruded molten film 3 was fed and introduced between the rotating first roll 4 and the rotating second roll 5, and pressed by the first roll 4 and the second roll 5. Subsequently, the pressed molten film 3 was held by the first roll 4 and sent out to the next rotating roll 6 to form a film 7 with a thickness of 100 μm. 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 winding speed was 18 m / min. The above tests (i) to (viii) were conducted. The blocking resistance in test (vii) was measured by the measuring method (1). The results are shown in Table 1.

[0092] Example 2 Using 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), a film-forming apparatus having an extrusion apparatus having an extruder 1 and a T-die 2, and a winding device having a mirror-finish metal roll (chill roll) and an air chamber was used, and a film with a thickness of 100 μm was formed under the conditions of a resin temperature at the T-die outlet of 220 °C, a surface temperature of the mirror-finish metal roll (chill roll) of 25 °C, and a winding speed of 18 m / min. The above tests (i) to (viii) were conducted. The blocking resistance in test (vii) was measured by the measuring method (1). The results are shown in Table 1.

[0093] Examples 3 to 19 Film formation and physical property measurement / evaluation were carried out in the same manner as in Example 1 except that one of those shown in any of Tables 1 to 4 was used as the resin mixture. The results are shown in any of Tables 1 to 4.

[0094]

Table 1

[0095]

Table 2

[0096]

Table 3

[0097]

Table 4

[0098] By the production method of the present invention, the film of the present invention could be suitably produced. The preferred film of the present invention was excellent in heat resistance, flexibility, transparency, solvent resistance, and blocking resistance, and had tensile properties suitable for the expansion process. Therefore, it could be suitably used as the base film of the dicing film.

[0099] Also, the haze of the base film of Example 1 (measured in accordance with JIS K7136:2000 using a turbidity meter "NDH2000" (trade name) of Nippon Denshoku Industries Co., Ltd.) was 84.8% (as the value output by the turbidity meter). Subsequently, 333 parts by mass (100 parts by mass in terms of solid content) of a transparent adhesive "Acrybase LKG-1013" (trade name) of Fujikura Kasei Co., Ltd., 1 part by mass of an isocyanate-based curing agent "CL-201" (trade name) of Fujikura Kasei Co., Ltd., and 222 parts by mass of ethyl acetate were used to prepare a coating for forming an adhesive layer. Using an applicator, the coating was applied onto the matte surface of the base film of Example 1 so that the film thickness after drying would be 10 μm. Then, this coating film was dried at a temperature of 85°C to form an adhesive layer, thereby obtaining a dicing film. The haze of the dicing film (measured in accordance with JIS K7136:2000 using a turbidity meter "NDH2000" (trade name) of Nippon Denshoku Industries Co., Ltd.) was 11.0%. As a result, it was confirmed that by forming an adhesive layer on the matte surface, the external haze caused by the unevenness of the matte surface was canceled, and sufficient transparency as a dicing film was ensured.

[0100] Optimization experiment of matting surface treatment conditions when corona surface treatment is applied Example 20 The 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-forming apparatus equipped with a rubber embossed roll having an arithmetic mean roughness (Ra) of 0.5 μm was used instead of the rubber embossed roll having an arithmetic mean roughness (Ra) of 1.5 μm as the second roll 5. The winding speed was changed from 18 m / min to 5 m / min. On both sides of the obtained film, a corona treatment power supply "AGI-020" manufactured by Kasuga Electric Co., Ltd. was used, and the discharge amount was 0.20 kW·min / m so that the wetting tension of the corona surface-treated surface of the film measured in accordance with JIS K6768:1999 would be 50 mN / m or more. 2Except for performing corona surface treatment under the condition described above, a film was formed in the same manner as in Example 1, and the blocking resistance of the formed film was measured by the measurement method (2) of (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 Except for using 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) and performing corona surface treatment on both sides of the obtained film, a film was formed in the same manner as in Example 1, and the blocking resistance of the formed film was measured by the measurement method (2) of (vii) above. That is, except for not changing the rubber embossed roll with an arithmetic mean roughness (Ra) of 1.5 μm as the second roll 5 in Example 1, film formation and physical property measurement of the film were performed in the same manner as in Example 20. The results are shown in Table 5.

[0102] Example 22 Except for using 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), replacing the smooth roll (mirror-finish metal roll) with a metal embossed roll with an arithmetic mean roughness (Ra) of 0.5 μm as the first roll 4, and using a film-forming apparatus equipped with a rubber embossed roll with an arithmetic mean roughness (Ra) of 0.5 μm instead of the rubber embossed roll with an arithmetic mean roughness (Ra) of 1.5 μm as the second roll 5, and performing corona surface treatment on both sides of the obtained film, a film was formed in the same manner as in Example 1, and the blocking resistance of the formed film was measured by the measurement method (2) of (vii) above. That is, except for further replacing the smooth roll with an embossed roll with an arithmetic mean roughness (Ra) of 0.5 μm as the first roll 4, film formation and physical property measurement of the film were performed in the same manner as in Example 20. The results are shown in Table 5.

[0103] Example 23 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-forming apparatus equipped with a grained metal roll having an arithmetic mean roughness (Ra) of 0.5 μm was used instead of the smooth roll (mirror-finish metal roll) as the first roll 4. The film was formed in the same manner as in Example 1 except that corona surface treatment was performed on both sides of the obtained film, and the blocking resistance of the formed film was measured by the above measurement method (2) of (vii). That is, film formation and physical property measurement of the film were performed in the same manner as in Example 22 except that a grained roll having an arithmetic mean roughness (Ra) of 1.5 μm was used instead of the grained roll having an arithmetic mean roughness (Ra) of 0.5 μm on one side. The results are shown in Table 5.

[0104]

Table 5

[0105] From the results shown in Table 5, it was found that the larger the arithmetic mean roughness (Ra) of the grained roll used for the dull surface treatment, that is, the deeper the depth of the grain transferred to the film surface, the more effectively blocking was suppressed. Also, it was found that blocking was more effectively suppressed when the dull surface treatment was performed on both sides of the film than when it was performed on only one side.

[0106] Film composition / presence or absence of corona surface treatment / optimization experiment of matting surface treatment conditions Example 24 A film was formed 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 formed film was measured by the above measurement method (3) of (vii). The results are shown in Table 6.

[0107] Example 25 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 was formed in the same manner as in Example 1 except that a film forming apparatus equipped with a metallic embossed roll having an arithmetic mean roughness (Ra) of 0.5 μm was used instead of the smooth roll (mirror-finish metal roll) as the first roll 4. The blocking resistance of the formed film was measured by the measurement method (3) of the above (vii). That is, film formation and physical property measurement of the film were performed in the same manner as in Example 24 except that a metallic embossed roll having an arithmetic mean roughness (Ra) of 0.5 μm was used instead of the smooth roll (mirror-finish metal roll) as the first roll 4. The results are shown in Table 6.

[0108] Example 26 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 was formed in the same manner as in Example 1 except that corona surface treatment was performed on both sides of the obtained film. The blocking resistance of the formed film was measured by the measurement method (3) of the above (vii). The results are shown in Table 6.

[0109] Example 27 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 forming apparatus equipped with a metallic embossed roll having an arithmetic mean roughness (Ra) of 0.5 μm was used instead of the smooth roll (mirror-finish metal roll) as the first roll 4, and corona surface treatment was performed on both sides of the obtained film. A film was formed in the same manner as in Example 1 except for the above, and the blocking resistance of the formed film was measured by the measurement method (3) of the above (vii). That is, film formation and physical property measurement of the film were performed in the same manner as in Example 26 except that a metallic embossed roll having an arithmetic mean roughness (Ra) of 0.5 μm was used instead of the smooth roll (mirror-finish metal roll) as the first roll 4. The results are shown in Table 6.

[0110] Example 28 A film was formed 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 the obtained film was subjected to corona surface treatment on both sides. The blocking resistance of the formed film was measured by the measurement method (3) of the above (vii). The results are shown in Table 6.

[0111] Example 29 A film was formed 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-forming apparatus equipped with a metallic embossed roll having an arithmetic mean roughness (Ra) of 0.5 μm was used instead of the smooth roll (mirror-finish metal roll) as the first roll 4, and the obtained film was subjected to corona surface treatment on both sides. The blocking resistance of the formed film was measured by the measurement method (3) of the above (vii). That is, film formation and physical property measurement of the film were carried out in the same manner as in Example 28, except that a metallic embossed roll having an arithmetic mean roughness (Ra) of 0.5 μm was used instead of the smooth roll (mirror-finish metal roll) as the first roll 4. The results are shown in Table 6.

[0112] Example 30 A film was formed 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 the obtained film was subjected to corona surface treatment on both sides. The blocking resistance of the formed film was measured by the measurement method (3) of the above (vii). The results are shown in Table 6.

[0113] Example 31 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-forming apparatus equipped with a metallic embossed roll having an arithmetic mean roughness (Ra) of 0.5 μm was used in place of the smooth roll (mirror-finish metal roll) as the first roll 4. Except for the fact that corona surface treatment was applied to both sides of the obtained film, a film was formed in the same manner as in Example 1, and the blocking resistance of the formed film was measured by the measurement method (3) of the above (vii). That is, film formation and physical property measurement of the film were performed in the same manner as in Example 30, except that a metallic embossed roll having an arithmetic mean roughness (Ra) of 0.5 μm was used in place of the smooth roll (mirror-finish metal roll) as the first roll 4. The results are shown in Table 6.

[0114] Example 32 A film was formed in the same manner as in Example 1, except that only the above component (A-1) was used as the resin (the mixture with component (B) was not used) and a film-forming apparatus equipped with a metallic embossed roll having an arithmetic mean roughness (Ra) of 0.5 μm was used in place of the smooth roll (mirror-finish metal roll) as the first roll 4. The blocking resistance of the formed film was measured by the measurement method (3) of the above (vii). The results are shown in Table 6.

[0115] Example 33 A film was formed in the same manner as in Example 1, except that only the above component (B-1) was used as the resin (the mixture with component (A) was not used) and corona surface treatment was applied to both sides of the obtained film. The blocking resistance of the formed film was measured by the measurement method (3) of the above (vii). The results are shown in Table 6. Regarding Examples 24 to 33, in Table 6, when mat surface treatment was performed on only one side of the film, it is expressed as "one-sided", and when mat surface treatment was performed on both sides of the film, it is expressed as "both-sided".

[0116]

Table 6

[0117] From the results shown in Table 6, it was further confirmed that blocking was more effectively suppressed when the matte surface treatment was performed on both sides of the film than when it was performed on only one side (similar to Table 5). Also, from these results, it was found that even when the corona surface treatment was performed on both sides, blocking was effectively suppressed by performing the matte surface treatment on both sides of the film.

[0118] Relationship between mass ratio of amorphous polypropylene region and film flexibility Example 34 Similar to Example 24, that is, 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 was formed in the same manner as in Example 1, and the above (v) tensile test was performed on the formed film, and (v-1) tensile modulus, (v-2) stress difference (Δσ), (v-3) 5% strain tensile stress, and 100% strain tensile stress were measured. The results are shown in Table 7.

[0119] Examples 35 to 41 As shown in Table 7, except that the types and blending amounts of components (A) and (B) were changed, a film was formed in the same manner as in Example 34, and the above (v) tensile test was performed on the formed film, and (v-1) tensile modulus, (v-2) stress difference (Δσ), (v-3) 5% strain tensile stress, and 100% strain tensile stress were measured. 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) 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 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: Melted film 4: First roll 5: Second roll 6: Rotating roll 7: Film

Claims

1. A base film for a dicing film, comprising a base film and an adhesive layer laminated directly or via an anchor coat on the base film, wherein the base film contains (A) crystalline polypropylene and (B) a polyolefin elastomer in a single film; the (B) polyolefin elastomer is a random copolymer composed of propylene and butene-1 and contains a random copolymer in which the mass ratio of the crystalline polypropylene region to the amorphous polypropylene region is in the range of 40:60 to 60:40, or alternatively, the (B) polyolefin elastomer is a random copolymer composed of propylene and butene-1 and contains a random copolymer in which the mass ratio of the crystalline polypropylene region to the amorphous polypropylene region is in the range of 40:60 to 60:40, and further contains at least one selected from the group consisting of a copolymer of ethylene and another α-olefin, a copolymer of 4-methyl-1-pentene and another α-olefin, a copolymer of ethylene, propylene, and 5-ethylidene-2-norbornene, a copolymer of an α-olefin and a non-conjugated diene compound, a copolymer of an α-olefin and an aromatic vinyl compound, and a copolymer of an α-olefin and an unsaturated carboxylic acid or an unsaturated carboxylic acid anhydride, The base film for a dicing film satisfying the following characteristics (i) to (iv): (i) The internal haze is 20% or less; (ii) The gloss of at least one surface is 40% or less; (iii) The melting point is 150°C or higher; (iv) The melting enthalpy is 30 to 90 J / g.

2. The base film for a dicing film according to Claim 1, wherein the gloss of both surfaces is 40% or less respectively.

3. The base film for a dicing film according to Claim 1 or 2, further satisfying the following characteristics (v-1) and (v-2): (v-1) The tensile elastic modulus in the machine direction is 600 MPa or less; (v-2) The difference between the tensile yield stress and the tensile descending yield stress in the machine direction is 2.5 MPa or less.

4. The base film for a dicing film according to claim 1 or 2, 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-based elastomer is 10% or more.

5. A dicing film comprising the base film for a dicing film according to any one of claims 1 to 4.

6. A method for forming a base film for a dicing film according to any one of claims 1 to 4, comprising: (1) A step of continuously extruding a molten film from a T-die using an extrusion device including an extruder and a T-die; (2) A step of supplying and charging 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 with the first roll and the second roll; and (3) A step of sending out the film pressed in the step (2) while holding it by the first roll to the next rotating roll wherein the textured roll is a grained rubber roll or a grained metal roll, and / or the smooth roll is a mirror-finish metal roll.

7. A method for manufacturing a dicing film according to claim 5, comprising: (1) A step of forming a base film for a dicing film by the method according to claim 6; and (2) A step of forming an adhesive layer on the surface of the base film for a dicing film obtained in the step (1) having a gloss of 40% or less. The method comprising.

8. A method for manufacturing a dicing film according to claim 5, comprising: (1) A step of forming a base film for a dicing film by the method according to claim 6; and (2) A step of forming an adhesive layer on the surface when there is a surface of the base film for a dicing film obtained in the step (1) having a gloss of 50% or more. The method comprising.

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