阅读说明：本技术 切割薄膜用基膜、切割薄膜以及制造方法 (Base film for dicing film, and method for producing the same ) 是由 白石雅也 新保光祐 于 2020-04-24 设计创作，主要内容包括：本发明的课题在于提供一种具有充分的柔软性与透明度且抗粘连性出色的切割薄膜用基膜、使用该切割薄膜用基膜的切割薄膜以及这些基膜和切割薄膜的制造方法。解决该课题的本发明为一种切割薄膜用基膜,其包含(A)结晶聚丙烯与(B)聚烯烃弹性体,且满足特性(i)～(iv):(i)内部浊度为20％以下；(ii)至少一个面的光泽度为40％以下；(iii)熔点为150℃以上；(iv)熔化焓为30～90J/g。两面的光泽度可以分别为40％以下。此外,可以满足以下要求：(v-1)机器方向的拉伸弹性模量为600MPa以下；(v-2)机器方向的拉伸屈服应力与拉伸下屈服应力的差为2.5MPa以下。(The invention provides a base film for a dicing film having sufficient flexibility and transparency and excellent blocking resistance, a dicing film using the base film for a dicing film, and a method for producing the base film and the dicing film. The present invention for solving the problem is a base film for a dicing film comprising (A) crystalline polypropylene and (B) a polyolefin elastomer, and satisfying the characteristics (i) to (iv) that (i) the internal haze is 20% or less; (ii) at least one surface has a gloss of 40% or less; (iii) the melting point is more than 150 ℃; (iv) the melting enthalpy is 30-90J/g. The glossiness of both surfaces may be 40% or less, respectively. Furthermore, the following requirements can be met: (v-1) a tensile modulus of elasticity in the machine direction of 600MPa or less; (v-2) the difference between the tensile yield stress in the machine direction and the yield stress under tension is 2.5MPa or less.)

1. A base film for a dicing film, comprising:

(A) crystalline polypropylene with (B) a polyolefin elastomer,

and satisfies the following characteristics (i) to (iv):

(i) an internal turbidity of 20% or less;

(ii) at least one surface has a gloss of 40% or less;

(iii) the melting point is more than 150 ℃;

(iv) the melting enthalpy is 30-90J/g.

2. The base film for a dicing film according to claim 1,

the glossiness of both surfaces is 40% or less.

3. The base film for a dicing film according to claim 1 or 2,

further satisfies the following characteristics (v-1) and (v-2):

(v-1) a tensile modulus of elasticity in the machine direction of 600MPa or less;

(v-2) the difference between the tensile yield stress in the machine direction and the yield stress under tension is 2.5MPa or less.

4. The base film for a dicing film according to claim 1 or 2,

(B) the polyolefin elastomer is a random copolymer of propylene and butene-1.

5. The base film for a dicing film according to claim 4,

the mass ratio of the crystalline polypropylene region to the amorphous polypropylene region in the random copolymer is in the range of 40:60 to 60: 40.

6. The base film for a dicing film according to claim 4 or 5,

the mass ratio of the amorphous polypropylene region in the random copolymer to the total mass of the crystalline polypropylene (A) and the random copolymer polyolefin elastomer (B) is 10% or more.

7. A dicing film characterized in that,

comprising the base film for a dicing film according to any one of claims 1 to 6.

8. A film forming method of cutting a base film for a film according to any one of claims 1 to 6, comprising the steps of:

(1) a process for continuously extruding a molten film from a T-die using an extrusion apparatus equipped with an extruder and a T-die;

(2) a process of supplying and charging the molten film between a first roll, which is a rotating smooth roll or an embossing roll, and a second roll, which is a rotating embossing roll, and molding the molten film by the first roll and the second roll; and

(3) a process of feeding out the first roll to the next rotating roll with the film embossed in the above process (2).

9. The method of claim 8,

the embossing roller is a satin rubber roller or a satin metal roller.

10. The method according to claim 8 or 9,

the smooth roll is a mirror metal roll.

11. A method for manufacturing a dicing film according to claim 7, comprising the steps of:

(1) a process of forming a base film for a dicing film by the method of any one of claims 8 to 10; and

(2) a process of forming an adhesive layer on the surface of the base film for dicing film obtained in the process (1) having a gloss of 40% or less.

12. A method for manufacturing a dicing film according to claim 7, comprising the steps of:

(1) a process of forming a base film for a dicing film by the method of any one of claims 8 to 10; and

(2) a process of forming an adhesive layer on the surface of the base film for dicing film obtained in the process (1) in the presence of the surface having a glossiness of 50% or more.

Technical Field

The present invention relates to a base film of an adhesive film (hereinafter referred to as a "dicing film") which is used in bonding to the front and/or back of a silicon wafer or the like for the purpose of protecting the front surface or the like when the silicon wafer or the like is diced (cut and separated), a dicing film using the base film, and a method for producing the base film and the dicing film.

Background

The semiconductor chips are produced by collectively forming a plurality of semiconductor chips on a large-diameter silicon wafer and then cutting the silicon wafer into individual semiconductor chips. This dicing process is generally performed by bonding a dicing film to the front surface and/or the back surface of a silicon wafer (having a plurality of semiconductor chips formed thereon) for the purpose of protecting the front surface of the semiconductor chip, fixing and picking up the diced individual semiconductor chip, and the like.

In particular, in the expanding process and the picking process, if the dicing tape has insufficient flexibility, the dicing tape may fall off from the annular rib, the dicing tape may be broken, the pitch of the diced wafer may be narrowed, the picking yield may be decreased, and the chips may be scattered and broken due to the load applied to the semiconductor wafer.

Conventionally, a base film of a cut film has been widely used for a flexible polyvinyl chloride resin composition film because of its advantages such as a high balance between heat resistance and flexibility, a stretch property suitable for an extension process, high transparency, and low cost. On the other hand, since a large amount of plasticizer is blended in the film of the flexible polyvinyl chloride resin composition, there are problems that the plasticizer transits to the adhesive, the adhesive property is unstable (the adhesive force is decreased or increased), and the plasticizer contaminates the semiconductor chip. Therefore, as a base film of a dicing film, a film of a polypropylene resin and a polypropylene resin composition is proposed (for example, refer to patent documents 1 to 3). However, these properties as a base film of a dicing film are inferior to those of a film of a soft polyvinyl chloride resin composition. In addition, films of polypropylene resins and polypropylene resin compositions have a problem that if sufficient flexibility and transparency are imparted as a base film of a cut film, blocking resistance is insufficient.

A base film for a dicing film having sufficient flexibility and transparency and excellent blocking resistance is required, but such a base film has not been developed so far.

However, the dicing film generally includes a base film for dicing film and an adhesive layer formed on a surface thereof. In order to improve the adhesiveness (anchoring property) between the base film for a dicing film and the adhesive layer, a corona discharge treatment is generally performed by irradiating corona discharge energy to the adhesive layer-formed surface of the base film for a dicing film. However, the corona discharge treatment has a problem that blocking is relatively likely to occur because the treated surface of the film is sticky. In fact, the corona discharge treatment may be performed on one side of the film or on both sides of the film, and in either case, the problem of blocking is likely to occur due to the corona discharge treatment.

Preferably, the base film for a dicing film has the above-described properties required, and can effectively prevent blocking even when corona discharge treatment (hereinafter, simply referred to as "corona surface treatment") is applied to the surface. However, such a base film has not been developed so far.

Prior art documents

Patent document

Patent document 1 Japanese patent application laid-open No. 2009-290001

Patent document 2 Japanese patent laid-open No. 2016-

Patent document 3 Japanese patent laid-open No. 2016-

Patent document 4 International publication No. 2011/055803

Patent document 5 Japanese patent laid-open No. 2015-093918

Patent document 6 Japanese patent laid-open No. 2015-096580

Disclosure of Invention

An object of the present invention is to provide a base film which is suitable for a dicing film, which can replace a film of a soft polyvinyl chloride resin composition, has sufficient flexibility and transparency, and is excellent in blocking resistance, a dicing film using the base film, and methods for producing the base film and the dicing film.

Another object of the present invention is to provide a base film which is suitable for a dicing film, which can be used in place of a film of a soft polyvinyl chloride resin composition, has sufficient flexibility and transparency, is excellent in blocking resistance, and can effectively prevent blocking even when corona surface treatment is performed, a dicing film using the base film, and a method for producing the base film and the dicing film.

The present inventors have conducted extensive studies and as a result have found that the above-mentioned problems can be achieved by a specific resin film.

Namely, various aspects of the present invention are as follows.

[1].

A base film for a dicing film, comprising:

(A) crystalline polypropylene with (B) a polyolefin elastomer,

and satisfies the following characteristics (i) to (iv):

(i) an internal turbidity of 20% or less;

(ii) at least one surface has a gloss of 40% or less;

(iii) the melting point is more than 150 ℃;

(iv) the melting enthalpy is 30-90J/g.

[2].

The base film for a dicing film according to item [1] above, wherein the glossiness of each of both surfaces is 40% or less.

[3].

The base film for a dicing film according to the above item [1] or [2], which further satisfies the following characteristics (v-1) and (v-2):

(v-1) a tensile modulus of elasticity in the machine direction of 600MPa or less;

(v-2) the difference between the tensile yield stress in the machine direction and the yield stress under tension is 2.5MPa or less.

[4].

The base film for a dicing film according to item [1] or [2], wherein the polyolefin elastomer (B) is a random copolymer of propylene and butene-1.

[5].

The base film for a dicing film according to item [4] above, wherein a mass ratio of the crystalline polypropylene region to the amorphous polypropylene region in the random copolymer is in a range of 40:60 to 60: 40.

[6].

The base film for a dicing film according to item [4] or [5], wherein a mass ratio of the amorphous polypropylene region in the random copolymer to a total mass of the (A) crystalline polypropylene and the (B) random copolymer polyolefin elastomer is 10% or more.

[7].

A dicing film comprising the base film for dicing film according to any one of the above [1] to [6 ].

[8].

A film forming method of the base film for a dicing film according to any one of the above [1] to [6], comprising the steps of:

(1) a process for continuously extruding a molten film from a T-die using an extrusion apparatus equipped with an extruder and a T-die;

(2) a process of supplying and charging the molten film between a first roll, which is a rotating smooth roll or an embossing roll, and a second roll, which is a rotating embossing roll, and molding the molten film by the first roll and the second roll; and

(3) a process of feeding out the first roll to the next rotating roll with the film embossed in the above process (2).

[9].

The method according to item [8] above, wherein the embossing roller is a satin rubber roller or a satin metal roller.

[10].

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

[11].

A method for producing a cut film according to the above item [7], comprising the steps of:

(1) a process for forming a base film for a dicing film by the method according to any one of the above [8] to [10 ]; and

(2) a process of forming an adhesive layer on the surface of the base film for dicing film obtained in the process (1) having a gloss of 40% or less.

[12].

A method for producing a cut film according to the above item [7], comprising the steps of:

(1) a process for forming a base film for a dicing film by the method according to any one of the above [8] to [10 ]; and

(2) a process of forming an adhesive layer on the surface of the base film for dicing film obtained in the process (1) in the presence of the surface having a glossiness of 50% or more.

Effects of the invention

The film of the present invention is not blended with a plasticizer, thereby fundamentally solving the problems caused by the plasticizer of the film of the flexible polyvinyl chloride resin composition. In addition, the film of the present invention has excellent flexibility, transparency and blocking resistance. The preferred films of the present invention also have excellent heat resistance, flexibility, transparency, solvent resistance, and blocking resistance, and have stretch properties suitable for the stretching process. Due to the flexibility of the base film for dicing film and the excellent flexibility of the dicing film, defects such as the dicing tape coming off the annular rib, the dicing tape breaking, the decrease in the yield of the pickup due to the narrow pitch of the diced wafer, and the chip flying and breaking due to the load on the semiconductor wafer can be effectively suppressed in the expanding process and the pickup process. The more preferable film of the present invention is excellent in blocking resistance particularly in the case of corona surface treatment in addition to the above-mentioned various properties. Therefore, the film of the present invention can be preferably used as a base film of a dicing film. The film of the present invention can be preferably produced by the production method of the present invention.

Drawings

FIG. 1 is a DSC curve of the film of example 1.

Fig. 2 is a schematic of a stress-strain curve.

FIG. 3 is a DSC curve of the crystalline polypropylene (A-1) used in the examples.

FIG. 4 is a DSC curve of the polyolefin elastomer (B-1) used in the examples.

FIG. 5 is a schematic view of a film formation apparatus used in examples.

FIG. 6 shows the polyolefin elastomer (B-1) used in the examples¹³C-NMR spectrum.

Detailed Description

In the present specification, the term "resin" is used as a term that also includes a resin mixture containing 2 or more resins, or a resin composition containing components other than the resins. In this specification, the term "film" may be used interchangeably or interchangeably with "sheet". In this specification, the terms "film" and "sheet" are used for articles that can be industrially rolled into a roll. The term "sheet" is used for articles that cannot be rolled up in industry into rolls. In the present specification, the sequential lamination of a certain layer and another layer includes two methods of directly laminating these layers and laminating these layers with 1 or more other layers such as an anchor coat layer interposed therebetween.

In the present specification, the term "above" in relation to a numerical range is used in the sense of a certain value or more. For example, "20% or more" means 20% or more than 20%. The term "below" in relation to a numerical range is used in the sense of a certain number or less. For example, "below 20% means 20% or less than 20%. The symbols "-" relating to a numerical range are used in the meaning of a certain numerical value, more than a certain numerical value and less than other numerical values, or other certain numerical values. Here, the other certain value is a value larger than the certain value. For example, "10-90%" means 10%, greater than 10% and less than 90% or 90%. In addition, the upper and lower limits of the numerical ranges may be arbitrarily combined, and embodiments in any combination may be read. For example, the range of values from a certain characteristic "is usually 10% or more, preferably 20% or more. On the other hand, it is usually 40% or less, preferably 30% or less. "or" is usually 10 to 40%, preferably 20 to 30% ", and a certain characteristic may be read as 10 to 40%, 20 to 30%, 10 to 30%, or 20 to 40% in one embodiment.

Except in the examples, or where otherwise indicated, all numbers expressing quantities used in the specification and claims are to be understood as being modified by the term "about". Without limiting the applicability of the doctrine of equivalents to the claims, each numerical value should be construed in light of the number of significant digits and by applying ordinary rounding techniques.

1. Base film for dicing film

The base film for a dicing film of the present invention has (i) an internal haze of usually 20% or less, preferably 15% or less, more preferably 12% or less, and still more preferably 10% or less. Since the internal haze in the above (i) is usually 20% or less, the transparency required for cutting the film, for example, visibility in laser printing can be sufficiently ensured. From the viewpoint of transparency, the lower limit of the internal haze in the above (i) is not particularly limited, and a lower value is preferable.

In this specification, the internal turbidity of (i) is measured by preparing 2 glass plates each having a smooth surface and coated with paraffin oil on one surface, sandwiching the sample between paraffin oil-coated surfaces of the 2 glass plates to prepare a measurement piece, and then measuring the turbidity according to JIS K7136: 2000. More specifically, the internal turbidity in the present specification can be measured by the method described in the following examples.

The base film for a dicing film of the present invention, (ii) at least one side of which has a gloss of usually 40% or less. Here, the gloss is a 60-degree gloss value measured in accordance with JIS Z8741: 1997. More specifically, the gloss in the present specification can be measured by the method described in the following examples.

Hereinafter, the surface of the base film for a dicing film of the present invention whose glossiness is adjusted to 40% or less may be referred to as "matte surface". In addition, in the industry, "matte surface" is sometimes referred to as "matte surface" or "matte finish surface". Since the matte surface of the base film for a dicing film of the present invention has a gloss of usually 40% or less, sufficient blocking resistance can be exhibited even if sufficient flexibility is imparted to the base film for a dicing film. Further, by forming the adhesive layer on the matt surface, external haze due to unevenness of the matt surface can be eliminated, and sufficient transparency of the dicing film can be ensured. In addition, since the matte surface has a large unevenness, the adhesive layer is formed on the matte surface, whereby 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 blocking resistance, 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, even more preferably 25% or less, even more preferably 20% or less, even more preferably 15% or less, even more preferably 10% or less, and most preferably 6% or less. On the other hand, the glossiness of at least one surface (matte surface) of the base film for dicing film may preferably be 1% or more from the viewpoint of smoothing the surface of the adhesive layer.

The arithmetic average roughness (Ra) of the matte surface of the base film for dicing film of the present invention may be usually 0.5 to 10 μm, preferably 1 to 5 μm, from the viewpoint of blocking resistance and from the viewpoint of smoothing the surface of the adhesive layer. In the present specification, the arithmetic average roughness (Ra) is measured in accordance with JIS B0601: 2013. More specifically, the arithmetic average roughness (Ra) in the present specification can be measured by the method described in the following examples.

In one embodiment, the base film for a dicing film of the present invention may have a glossiness of 40% or less on one surface and a glossiness of 50% or more on the other surface. Hereinafter, the surface of the base film for a dicing film of the present invention whose glossiness is adjusted to 50% or more may be referred to as "glossy surface". Since the gloss of the glossy surface is usually 50% or more, sufficient transparency of the base film for a dicing film can be ensured. From the viewpoint of transparency, 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, still more preferably 65% or more, still more preferably 70% or more, still more preferably 75% or more, still more preferably 80% or more, and most preferably 85% or more. 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 blocking resistance.

In another embodiment, generally, the glossiness of both sides of the base film for a dicing film of the present invention may be 40% or less, respectively. That is, both sides of the base film for dicing film of the present invention may be matte surfaces (matte surfaces). In the present embodiment, since the gloss of any one of the matte surfaces can be independently adjusted, the gloss on both sides may be substantially equal or different.

Since the gloss of each matte surface of the base film for a dicing film of the present embodiment is usually 40% or less, sufficient blocking resistance can be exhibited even if sufficient flexibility is imparted to the base film for a dicing film. Further, by forming the adhesive layer on the matt surface, external haze due to unevenness of the matt surface can be eliminated, and sufficient transparency of the dicing film can be ensured. In addition, since the matte surface has a large unevenness, the adhesive layer is formed on the matte surface, whereby 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.

Further, since the gloss of each matte surface of the base film for a dicing film of the present embodiment is usually 40% or less, excellent blocking resistance can be obtained even when the corona discharge treatment is applied to the adhesive layer forming surface of the base film for a dicing film to improve the adhesion (anchorage) with the adhesive layer. This advantage can be obtained both in the case where one surface of the film is subjected to corona discharge treatment and in the case where both surfaces are subjected to corona discharge treatment.

From the viewpoint of blocking resistance, the gloss of each matte surface of the base film for a dicing film of the present embodiment may be, independently of each other, preferably 35% or less, more preferably 30% or less, still more preferably 25% or less, further preferably 20% or less, still further preferably 15% or less, still further preferably 10% or less, and most preferably 6% or less. On the other hand, the gloss of each matte surface of the base film for a dicing film of the present embodiment may preferably be 1% or more from the viewpoint of smoothing the surface of the adhesive layer.

The base film for a dicing film of the present invention (iii) has a melting point of usually 150 ℃ or higher, preferably 155 ℃ or higher, and more preferably 160 ℃ or higher. The melting point of (iii) is 150 ℃ or higher, and therefore, the heat resistance required for cutting the film can be sufficiently ensured. In addition, the solvent resistance required for forming an adhesive layer on the surface (usually matte surface) of the base film for dicing film of the present invention can be sufficiently ensured. From the viewpoint of heat resistance and solvent resistance, the higher the melting point of the above-mentioned (iii), the better.

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

In the present specification, the melting point (iii) and the enthalpy of fusion (iv) are calculated from a DSC first melting curve measured by a procedure of holding at 25 ℃ for 5 minutes and then warming to 190 ℃ at 10 ℃/min according to JIS K7121-1987 using a differential scanning calorimeter (DSC measuring apparatus). In this case, the melting point (iii) is the peak top temperature of the melting peak appearing in the DSC first melting curve. When 2 or more melting peaks are observed, the melting point (iii) is defined as the peak top temperature of the melting peak having the largest peak top height. FIG. 1 shows an example of DSC measurement in example 1. In FIG. 1, the bottom curve is the DSC first melting curve, the top curve is the DSC crystallization curve, and the middle curve is the DSC second melting curve. It should be noted that the melting peak appearing in the DSC first melting curve of the crystalline polypropylene resin composition is generally a curve under the peak foot on the low temperature side which is gently elongated, and that a straight line drawn so that the base line on the high temperature side shown in FIG. 1 in the reading method of the 9.DTA or DSC curve of JIS K7121-1987 is extended to the low temperature side coincides with a straight line extending the base line on the same low temperature side to the high temperature side.

More specifically, the melting point and the enthalpy of fusion in the present specification can be measured by the methods described in the following examples.

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

From the viewpoint of flexibility, the tensile elastic modulus (hereinafter, simply referred to as "tensile elastic modulus TD") measured under the condition that the transverse direction (direction orthogonal to the machine direction) of the base film for a dicing film of the present invention is the stretching direction may be generally 800MPa or less, preferably 700MPa or less, more preferably 600MPa or less, and still more preferably 550MPa or less. On the other hand, the tensile elastic modulus TD may be generally 100MPa or more, preferably 200MPa or more, more preferably 300MPa or more, and still more preferably 350MPa or more, from the viewpoint of stability of film formation.

In the stretching process after the slitting process, 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 slit films of the present invention may be 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 present specification, the tensile elastic modulus MD was calculated by a method based on the gradient of 2 points of item 10.3.2 of JIS K7161-1:2014, regardless of the calculation and the representation of the result of item 10 of JIS K7127:1999, using a test piece punched from a film into the shape of test piece type 5 (fig. 2 of the JIS standard) of the above standard so that the machine direction of the film becomes the stretching direction, and the stress-strain curve (hereinafter, simply referred to as "SS curve") obtained by performing a stretching test under the conditions of the stretching speed of 200mm/min and the temperature of 23 ℃. Note that, regardless of the definition of item 10.3.2 in JIS K7161-1:2014, σ 1 is a stress (MPa) at which strain ∈ 1 becomes 0.8%, and σ 2 is a stress (MPa) at which strain ∈ 2 becomes 1.6%. The tensile modulus TD was measured and calculated in the same manner except that the test piece was punched so that the transverse direction of the film was the stretching direction.

More specifically, the tensile modulus of elasticity MD and the tensile modulus of elasticity TD in the present specification can be measured by the methods described in the following examples.

From the viewpoint of the stretching process suitable for cutting, the stress difference (Δ σ) (hereinafter, simply referred to as "stress difference MD") between the tensile yield stress (σ y) measured under the condition that the machine direction is the stretching direction and the tensile yield stress (σ 1) (the stress at the point (σ 1) where the tensile stress decreases with an increase in the tensile strain changes again to increase after the tensile strain exceeds the tensile yield strain (∈ y)) and the tensile yield stress (σ 1) may be generally 3MPa or less, preferably 2.5MPa or less, more preferably 2MPa or less, still more preferably 1MPa or less, and still more preferably 0.5MPa or less. From the viewpoint of expandability, the smaller the stress difference MD, the better.

From the viewpoint of the stretching process suitable for cutting, the stress difference (Δ σ) between the tensile yield stress (σ y) and the yield stress (σ 1) under tension (hereinafter, simply referred to as "stress difference TD") measured under the condition that the transverse direction (direction orthogonal to the machine direction) is the stretching direction of the base film for a cut film of the present invention may be generally 3MPa or less, preferably 2MPa or less, more preferably 1MPa or less, and still more preferably 0.5MPa or less. From the viewpoint of expandability, the smaller the stress difference TD, the better.

In the present specification, a test piece having a shape of test piece type 5 (fig. 2 of the JIS standard) punched from a film so that the machine direction of the film is the stretching direction was used according to JIS K7127:1999, and the tensile yield stress (σ y) was determined as the stress in the tensile yield strain (∈ y) according to item 10.1 of JIS K7161-1:2014 using the SS curve obtained by the tensile test under the conditions of the stretching speed of 200mm/min and the temperature of 23 ℃. A schematic of the stress-strain curve is shown in fig. 2. The stress difference TD was measured and calculated in the same manner except that the test piece was punched so that the transverse direction of the film was the stretching direction.

More specifically, the stress difference MD and the stress difference TD in the present specification can be measured by the methods described in the following examples.

The thickness of the base film for a dicing film of the present invention is not particularly limited, and may be appropriately selected in consideration of use as the base film for a dicing film. The thickness of the base film for a dicing film of the present invention may be generally 30 to 300. mu.m, preferably 50 to 200. mu.m, and more preferably 70 to 150. mu.m.

The base film for a dicing film of the present invention comprises (a) crystalline polypropylene and (B) a polyolefin elastomer. Hereinafter, each component will be described.

(A) Crystalline polypropylene

The base film for a dicing film of the present invention comprises the above-mentioned crystalline polypropylene of component (a). The crystalline polypropylene of the component (a) plays a role in making the base film for a dicing film of the present invention excellent in heat resistance and solvent resistance.

The crystalline polypropylene of the component (a) is a resin mainly containing a structural unit derived from propylene and having a high crystallinity. Here, "mainly including a structural unit derived from propylene" means that the content of the structural unit 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%. The crystalline polypropylene "having a higher crystallinity" as the component (A) means that the enthalpy of fusion (measurement method described later) is usually 50J/g or more. In one embodiment, the enthalpy of fusion of the crystalline polypropylene of component (A) may be preferably 60J/g or more, more preferably 65J/g or more, and still more preferably 70J/g or more.

When the crystalline polypropylene of the component (a) is an isotactic polypropylene, the meso-dyad fraction (the proportion of isotactic structure in the three-dimensional structure of the structural units derived from 2 consecutive propylene) may be 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 dyad fraction (the proportion of the syndiotactic structure in the three-dimensional structure of the structural unit derived from 2 consecutive propylene units) may be usually 80 mol% or more, preferably 90 mol% or more, more preferably 95 mol% or more, and typically 97 to 100 mol%.

As the crystalline polypropylene of the component (A), there may be mentioned, for example, propylene homopolymers; copolymers (including block copolymers and random copolymers) of 1 or 2 or more kinds of propylene and other small amounts of α -olefins (e.g., ethylene, 1-butene, 1-hexene, 1-octene, and 4-methyl-1-pentene). Here, such a block copolymer of propylene with other small amount of α -olefin as the component (a) may contain amorphous regions or amorphous blocks in addition to crystalline regions or crystalline blocks.

Among these, the crystalline polypropylene of the component (a) is preferably a block copolymer of 1 or 2 or more species of propylene and other small amount of α -olefin, from the viewpoint of making the melting point and melting enthalpy of the base film for dicing film within predetermined ranges and from the viewpoint of making the melting point and melting enthalpy of the crystalline polypropylene of the component (a) within the preferable ranges described below. As the crystalline polypropylene as the component (A), a mixture of 1 or 2 or more of these block copolymers can be used.

The melting point of the crystalline polypropylene of the component (a) may be preferably 150 ℃ or higher, more preferably 155 ℃ or higher, and still more preferably 160 ℃ or higher, from the viewpoint of heat resistance and solvent resistance. The higher the melting point of the crystalline polypropylene of the component (A), the better from the viewpoint of heat resistance and solvent resistance. In addition, from the viewpoint of heat resistance and solvent resistance, it is preferable that the crystalline polypropylene as the component (a) does not have a sub-peak, that is, a peak having a peak top temperature of less than 150 ℃.

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

In this specification, the melting point and enthalpy of fusion of the above-mentioned component (A), crystalline polypropylene, are calculated by a second melting curve (melting curve measured during the last temperature rise) measured by following the procedure of keeping at 190 ℃ for 5 minutes, cooling at 10 ℃/min to-10 ℃, keeping at-10 ℃ for 5 minutes, warming at 10 ℃/min to 190 ℃ in accordance with JIS K7121-1987 using a differential scanning calorimeter (DSC measuring apparatus). At this time, the melting point is the peak top temperature of the melting peak appearing in the above-described second melting curve. When 2 or more melting peaks were observed, the melting point was defined as the peak top temperature of the melting peak having the largest peak top height. FIG. 3 shows an example of DSC measurement of the following component (A-1) used in examples. The lower curve of FIG. 3 is the DSC second melting curve, and the upper curve is the DSC crystallization curve. It should be noted that the melting peak appearing in the DSC second melting curve of the crystalline polypropylene is generally a curve under the peak foot on the low temperature side which is gently elongated, and that a straight line drawn so that the base line on the high temperature side shown in FIG. 1 in the reading method of the 9.DTA or DSC curve of JIS K7121-1987 is extended to the low temperature side coincides with a straight line extending the base line on the same low temperature side to the high temperature side.

The melt mass flow rate of the component (A) may be preferably 0.1 to 50g/10 min, more preferably 0.5 to 20g/10 min, and still more preferably 1 to 10g/10 min, from the viewpoint of film formability. The melt mass flow of the above component (A) was measured at 230 ℃ under 21.18N in accordance with JIS K7210-1: 2014.

(B) Polyolefin elastomer

The base film for a dicing film of the present invention comprises the above-mentioned component (B) a polyolefin elastomer. The polyolefin elastomer of the component (B) plays a role of imparting excellent flexibility to the base film for a dicing film of the present invention and tensile characteristics suitable for a stretching process.

The polyolefin elastomer as the component (B) is an elastomer mainly containing a structural unit derived from an α -olefin (usually 50 mol% or more, preferably 70 mol% or more, more preferably 90 mol% or more, and typically 95 to 100 mol%).

Here, the term "elastomer" as used herein with respect to the polyolefin elastomer as the component (B) means that the enthalpy of fusion (measurement method will be described later) is usually 45J/g or less.

In one embodiment, the enthalpy of fusion of the polyolefin elastomer of component (B) may be preferably 15J/g or less, more preferably 10J/g or less, still more preferably 5J/g or less, and most preferably 0J/g (no melting peak observed in the DSC second melting curve).

In another embodiment, the enthalpy of fusion of the polyolefin elastomer of component (B) may preferably be in the range of 10J/g to 20J/g, more preferably in the range of 10J/g to 15J/g.

In another embodiment, the enthalpy of fusion of the polyolefin elastomer of component (B) may be preferably in the range of 25J/g to 40J/g, more preferably in the range of 30J/g to 40J/g, and still more preferably in the range of 30J/g to 35J/g.

In this specification, the melting point and enthalpy of fusion of the polyolefin elastomer of the above-mentioned component (B) are calculated by a second melting curve (melting curve measured during the last temperature rise) measured by following the procedure of keeping at 190 ℃ for 5 minutes, cooling at 10 ℃/min to-50 ℃ and keeping at-50 ℃ for 5 minutes, warming at 10 ℃/min to 190 ℃ in accordance with JIS K7121-1987 using a differential scanning calorimeter (DSC measuring apparatus). At this time, the melting point is the peak top temperature of the melting peak appearing in the above-described second melting curve. When 2 or more melting peaks were observed, the melting point was defined as the peak top temperature of the melting peak having the largest peak top height. In addition, it should be noted that the melting peak appearing in the DSC second melting curve of the elastomer, usually the curve under the peak leg, is gently elongated on both the high temperature side and the low temperature side, and that drawing a base line makes a straight line extending from the base line on the high temperature side to the low temperature side shown in fig. 1 in the method of reading the 9.DTA or DSC curve of JIS K7121-1987 coincide with a straight line extending from the base line on the same low temperature side to the high temperature side. FIG. 4 shows an example of DSC measurement of the following component (B-1) used in examples. The lower curve of FIG. 4 is the DSC second melting curve, and the upper curve is the DSC crystallization curve. No melting peak was observed in the DSC second melting curve of the following component (B-1).

Examples of the α -olefin include a linear α -olefin and a branched α -olefin. Examples of the linear alpha-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 the branched chain include 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3-ethyl-1-pentene, 4-dimethyl-1-pentene, 4-methyl-1-hexene, 4-dimethyl-1-hexene, 4-ethyl-1-hexene, and 3-ethyl-1-hexene. Among these, the α -olefin is preferably one having 2 to 8 carbon atoms. As the above-mentioned alpha-olefin, 1 or 2 or more of these may be used.

The polyolefin elastomer as the component (B) may contain a structural unit derived from a monomer copolymerizable with the above-mentioned α -olefin in addition to the above-mentioned 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. As the copolymerizable monomer, 1 or 2 or more of these may be used.

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

Among these, a copolymer of 4-methyl-1-pentene and 1 or more other α -olefins (in the industry, sometimes referred to as "TPX elastomer") is preferable from the viewpoint of the balance between flexibility and blocking resistance as the polyolefin elastomer (B). The copolymer more preferably contains a structural unit derived from 4-methyl-1-pentene, and is usually 50 to 90 mol%, preferably 60 to 80 mol%, and more preferably 65 to 75 mol%. Here, the sum of all kinds of structural units is 100 mol%. The enthalpy of fusion of such a copolymer of 4-methyl-1-pentene and other 1 or 2 or more alpha-olefins may preferably be 15J/g or less, more preferably 10J/g or less, still more preferably 5J/g or less, and most preferably 0J/g (no melting peak observed in the DSC second melting curve).

The polyolefin elastomer as the component (B) is preferably a copolymer comprising a structural unit derived from 4-methyl-1-pentene and a structural unit derived from propylene, and the copolymer comprises a structural unit derived from 4-methyl-1-pentene in an amount of usually 50 to 90 mol%, preferably 60 to 80 mol%, more preferably 65 to 75 mol%, and a structural unit derived from propylene in an amount of usually 10 to 50 mol%, preferably 20 to 40 mol%, more preferably 25 to 35 mol%, from the viewpoints of the balance between flexibility and blocking resistance and the miscibility with the crystalline polypropylene as the component (a). Here, the sum of all kinds of structural units is 100 mol%. Examples of such copolymers include a copolymer of 4-methyl-1-pentene and propylene, a copolymer of 4-methyl-1-pentene, propylene and 1 or 2 or more other alpha-olefins.

In another embodiment, the polyolefin elastomer as the component (B) is preferably a random copolymer of propylene and butene-1 from the viewpoint of balance between flexibility and blocking resistance.

It is estimated that the mass ratio of the crystalline polypropylene region to the amorphous polypropylene region in the random copolymer comprising propylene and butene-1 varies within the range of usually 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 further preferably 30:70 to 70: 30. Accordingly, a better balance of softness and blocking resistance can be obtained. From the viewpoint of obtaining such characteristics, the enthalpy of fusion of the random copolymer composed of propylene and butene-1 may be preferably in the range of 10J/g to 20J/g, and more preferably in the range of 10J/g to 15J/g.

Further, from the viewpoint of the balance between flexibility and blocking resistance, as described above, and from the viewpoint of obtaining excellent blocking resistance even when the base film for a dicing film is subjected to corona surface treatment, it is presumed that the mass ratio of the crystalline polypropylene region to the amorphous polypropylene region in the random copolymer composed of propylene and butene-1 may be preferably 35:65 to 65:35, more preferably 40:60 to 60:40, still more preferably 45:55 to 55:45, and most preferably actually 50:50 (for example, 48:52 to 52: 48). From the viewpoint of obtaining such characteristics, the enthalpy of fusion of the random copolymer composed of propylene and butene-1 may be preferably in the range of 25J/g to 40J/g, more preferably 30J/g to 40J/g, and still more preferably 30J/g to 35J/g.

The melt mass flow rate of the polyolefin elastomer as the component (B) may be preferably 0.1 to 50g/10 min, more preferably 0.5 to 20g/10 min, and still more preferably 1 to 10g/10 min, from the viewpoint of film formability. The melt mass flow rate of the component (B) was measured at 230 ℃ under 21.18N in accordance with JIS K7210-1: 2014.

The blending ratio of the crystalline polypropylene of the component (a) and the polyolefin elastomer of the component (B) is suitably determined in consideration of the enthalpy of fusion of the crystalline polypropylene of the component (a) and the enthalpy of fusion of the polyolefin elastomer of the component (B) from the viewpoint of setting the enthalpy of fusion of the component (iv) of the base film for a dicing film of the present invention to 30 to 90J/g. On the basis of the following examples, the additivity of the melting enthalpy is basically established. Therefore, for example, when it is desired to set the melting enthalpy (iv) to 60J/g, the amount B parts by mass of the component (B) relative to 100 parts by mass of the amount of the component (a) can be determined by solving the following equation (1) for B parts by mass.

(100·ΔH_A+b·ΔH_B)/(100+b)＝60… (1)

Here,. DELTA.H_AThe enthalpy of fusion (J/g), Δ H, of the above-mentioned component (A)_BThe enthalpy of fusion (J/g) of the above component (B). When the desired enthalpy of fusion (iv) described above is generalized to Δ H, the following equation (2) can be solved for b.

(100·ΔH_A+b·ΔH_B)/(100+b)＝ΔH… (2)

Here,. DELTA.H is the desired melting enthalpy (J/g) of the component (IV), and. DELTA.HA is the melting enthalpy (J/g) of the component (A), and. DELTA.H_BThe enthalpy of fusion (J/g) of the above component (B).

As demonstrated by the following examples, the greater the mass ratio of the amorphous polypropylene region in the random copolymer as the component (B) with respect to the total mass of the components (a) and (B) contained in the base film for a dicing film (the greater the mass ratio of the amorphous polypropylene region with respect to the total mass of the base film for a dicing film), the more excellent the flexibility of the film tends to be.

Further, in the base film for a dicing film of the present invention, optional component(s) known in the industry may be contained in addition to the above components (a), (B). The proportion of such optional components is not particularly limited, and may be, for example, 5% by mass or less relative to the total mass of the composition of the film. Preferably, the plasticizer does not contain such optional ingredients.

2. Film forming method

The method for forming the base film for a dicing film of the present invention is not particularly limited, and the film can be formed by any method.

As a preferable method for forming the base film for a dicing film of the present invention, there can be mentioned, for example, a method including the following steps:

(1) a process for continuously extruding a molten film from a T-die using an extrusion apparatus equipped with an extruder and a T-die;

(2) a process of supplying and charging the molten film between a first roll, which is a rotating smooth roll or an embossing roll, and a second roll, which is a rotating embossing roll, and embossing the molten film by the first roll and the second roll (in the case where both surfaces are made to be "matte surfaces" ("matte-treated surfaces"), an embossing roll is used as the first roll); and

(3) a process of feeding out the first roll to the next rotating roll with the film embossed in the above process (2).

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

In order to suppress deterioration of the raw material resin, it is preferable to perform nitrogen purging inside the extruder. The raw resin is preferably dried before forming a film. Further, it is preferable that the resins dried by the dryer are directly conveyed from the dryer to the extruder and charged.

The T-letter used in the process (1) is not particularly limited, and any T-letter may be used. Examples of the T-shaped form include a manifold form, a fishtail form, and a clothes hanger form.

From the viewpoint of stably carrying out the process of continuously extruding a molten film, the set temperature of the T-die outlet (die lip) may be usually 200 ℃ or higher, preferably 220 ℃ or higher, and more preferably 230 ℃ or higher. On the other hand, the set temperature of the T-block may be usually 300 ℃ or lower, preferably 280 ℃ or lower, and more preferably 260 ℃ or lower, from the viewpoint of suppressing deterioration of the raw material resin.

The smoothing roll (when used) used in the process (2) may be appropriately selected from the viewpoint of making the gloss of the glossy surface of the base film for a dicing film of the present invention 50% or more. The smoothing roll is preferably a mirror-surface roll in view of making the glossiness of one surface of the base film for a dicing film of the present invention preferably 55% or more, more preferably 60% or more, still more preferably 65% or more, more preferably 70% or more, still more preferably 75% or more, still more preferably 80% or more, and most preferably 85% or more.

The mirror surface roller is a roller whose surface is mirror-finished. Examples of the mirror-surface roller include mirror-surface rollers made of metal, ceramic, or rubber. For the purpose of preventing corrosion and scratches, the surface of the mirror roller may be subjected to chrome plating, iron-phosphorus alloy plating, hard carbon treatment by PVD method or CVD method, or the like.

The mirror finishing is not limited and may be performed by any method. The mirror finishing may be performed, for example, by polishing with a fine abrasive grain so that the arithmetic average roughness (Ra) of the surface of the mirror surface is preferably 100nm or less, more preferably 50nm or less, or the ten-point average roughness (Rz) is preferably 500nm or less, more preferably 250nm or less.

In the present specification, the arithmetic average roughness (Ra) and the ten-point average roughness (Rz) are measured in accordance with JIS B0601: 2013.

The smooth roll used in the process (2) functions as a cooling roll when used. In the step (3) of feeding the film to the next rotating roll, the smoothing roll is preferably a metal roll from the viewpoint of complete cooling and solidification of the film. The smoothing roll is more preferably a mirror-surface metal roll from the viewpoint of making the gloss of the glossy surface of the base film for a dicing film of the present invention 50% or more and from the viewpoint of completely cooling and solidifying the film when the film is fed to the next rotating roll in the above process (3).

The surface temperature of the smoothing roll (in the case of use) used in the process (2) may be appropriately selected from the viewpoint of making the gloss level of the glossy surface of the base film for a dicing film of the present invention 50% or more, the viewpoint of completely cooling and solidifying the film when the film is fed to the next rotating roll in the process (3), and the viewpoint of preventing the surface of the smoothing roll from being coagulated. The surface temperature of the smoothing roll may be usually 80 ℃ or less, preferably 60 ℃ or less, and more preferably 50 ℃ or less, from the viewpoint of increasing the supercooling degree (the temperature difference between the surface temperature of the smoothing roll and the temperature of the molten film before the smoothing roll comes into contact) to increase the glossiness of the glossy surface to 50% or more, and from the viewpoint of completely cooling and solidifying the film when the film is fed to the next rotating roll in the process (3). On the other hand, the surface temperature of the smoothing roll depends on the temperature and humidity of the film forming environment, but may be usually 15 ℃ or more, preferably 20 ℃ or more, and more preferably 25 ℃ or more, from the viewpoint of preventing the surface of the smoothing roll from being coagulated.

The embossing roll used in the process (2) may be appropriately selected from the viewpoint of making the matte surface gloss of the base film for a dicing film of the present invention 40% or less. The embossing roller is a roller whose surface is embossed, and typically is a satin-finished roller (satin roller). Examples of the embossing roll include embossing rolls whose surface is made of metal, ceramic, or rubber. When used as the second roller, the surface of the corrugated roller is preferably made of rubber, from the viewpoint of low thermal conductivity (cooling efficiency) and easy reduction in glossiness, and from the viewpoint of easy film formation (for example, the problem of the smooth roller being less likely to be damaged). From the above viewpoint, when used as the second roller, the embossing roller is more preferably a satin rubber roller. On the other hand, in the case of using as the first roll, in the above process (3), the embossing roll may preferably be made of metal, typically a satin metal roll, from the viewpoint of completely cooling and solidifying the film when the film is fed to the next rotating roll.

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

The surface temperature of the embossing roll used in the process (2) may be appropriately selected from the viewpoint of making the matte surface of the base film for a dicing film of the present invention 40% or less in gloss, the viewpoint of suppressing and preventing the problem of the molten film adhering to the embossing roll, and the viewpoint of preventing the surface of the embossing roll from being coagulated. The surface temperature of the embossing roll may be generally 80 ℃ or less, preferably 70 ℃ or less, and more preferably 60 ℃ or less, from the viewpoint of suppressing and preventing the problem of adhesion of a molten film to the embossing roll. On the other hand, from the viewpoint of making the matte surface gloss of the base film for a dicing film of the present invention 40% or less and the viewpoint of preventing the surface of the embossing roll from being coagulated, the surface temperature of the embossing roll may be generally 15 ℃ or more, preferably 30 ℃ or more, and more preferably 40 ℃ or more, although it depends on the material of the surface of the embossing roll, the temperature and humidity of the film forming environment. In one embodiment, cooling water may be used for the embossing roll as needed in process (2).

The above-mentioned process (3) is a process of feeding out the first roll to the next rotating roll with the film embossed in the above-mentioned process (2). By bringing the molten film to the first roll, it is possible to easily achieve complete cooling and solidification of the molten film at the time of feeding to the next rotating roll.

Fig. 5 is a schematic view of a film forming apparatus according to an embodiment used in examples (in the case of manufacturing a base film for dicing film having a matte surface (matte surface) on one side and a glossy surface on the other side). The raw material resin is passed through an extrusion apparatus equipped with an extruder 1 and a T-die 2 to form a molten film 3, and continuously extruded from the T-die 2. Next, the molten film 3 fed and extruded is supplied between the rotating first roll (in this case, smooth roll) 4 and the rotating second roll (embossing roll) 5, and is molded by the first roll 4 and the second roll 5. The molten film 3 thus molded is carried by the first roll 4 to the next rotating roll 6, and then becomes a completely cooled and solidified film 7.

3. Cutting film

The dicing film of the present invention is a dicing film having the base film for dicing film of the present invention as a base film. The adhesive layer of the dicing film of the present invention is usually formed on the matte side of the base film for dicing film of the present invention directly or through an anchor coat layer.

The adhesive used for forming the above adhesive layer is not particularly limited, and any adhesive may be used. Examples of the binder used for forming the adhesive layer include acrylic binders such as polyalkyl (meth) acrylates, copolymers of alkyl (meth) acrylates with other monomers; rubber adhesives such as natural rubber and butyl-isoprene rubber; a polyurethane adhesive; a polyester binder; polystyrene adhesives, and silicon adhesives.

From the viewpoint of ensuring sufficient transparency required for cutting the film, for example, visibility during laser printing, an adhesive excellent in transparency is preferred as the adhesive for forming the adhesive layer. Here, the "adhesive excellent in 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. The visible light transmittance can be calculated as a ratio of an integrated area of a transmission spectrum at a wavelength of 380 to 780 nm of the binder measured by using a spectrophotometer "Solid Spec-3700" (trade name) manufactured by Shimadzu corporation and a quartz groove having an optical path length of 10mm to an integrated area of a transmission spectrum in a case where the transmittance is assumed to be 100% in a total range of 380 to 780 nm.

As the adhesive for forming the adhesive layer, an adhesive capable of reducing the adhesive strength by heat curing or active energy ray curing is preferable. By reducing the adhesive strength, the dicing film can be peeled off from the work cleanly and without leaving any adhesive. Examples of the binder that can reduce the adhesive strength by the heat curing or the active energy ray curing include binders having 2 or more reactive functional groups (for example, amino groups, vinyl groups, epoxy groups, methacryloxy groups, acryloxy groups, isocyanate groups, and the like) in 1 molecule; an adhesive composition comprising the adhesive, at least 1 or more isocyanate curing agent, photopolymerization initiator, organic peroxide and the like.

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

[ examples ] A method for producing a compound

Measurement method

(i) Internal turbidity

2 pieces of float glass (thickness 2mm) defined in JIS R3202:2011 was coated with paraffin oil ("MORESCO WHITEP-350P" (trade name) available from MORESCO, Inc.) on one surface thereof. Next, the sample was sandwiched between the paraffin-coated surfaces of the 2 glass plates as a measurement piece. Then, the turbidity measured using a turbidity meter "NDH 2000" (trade name) manufactured by Nippon Denshoku industries Co., Ltd., according to JIS K7136:2000 was defined as the internal turbidity.

(ii) Gloss (60 degree gloss value)

The gloss (60-degree gloss value) was measured according to JIS Z8741:1997 using a multi-angle gloss meter "GM-268" (trade name) manufactured by KONICAMINOLTA corporation. Both sides of the sample were measured. In the table, the value of the surface on the smooth roll (mirror metal roll) side at the time of film formation is shown in the column of "gloss of glossy surface", and the value of the other surface (surface on the embossing roll (satin rubber roll)) is shown in the column of "gloss of matte surface".

(iii) Melting Point

The melting point of the base film for dicing film was measured as follows. According to JIS K7121-1987, the temperature of the melting point of the melting peak appearing on the first melting curve of DSC measured by a temperature program of increasing the temperature at a rate of 10 ℃/min to 190 ℃ was calculated as the melting point after keeping the sample at 25 ℃ for 5 minutes using a differential scanning calorimeter "Diamond DSC" (trade name) of Perkinelmer. When 2 or more melting peaks were observed, the peak top temperature of the melting peak having the largest peak top height was taken as the melting point. In addition, the peak top temperature of the sub-peak (melting peak other than the melting peak having the largest peak top height) is shown in the sub-peak column of the table. In addition, in the column of the sub-peak in the table, "-" means that no sub-peak is observed (1 melting peak).

Further, according to JIS K7121-1987, the melting point of the above-mentioned component (A), crystalline polypropylene, was calculated by using a differential scanning calorimeter "Diamond DSC" (trade name) of Perkinelmer company, by following a second melting curve (melting curve measured during the last temperature raising) measured by keeping at 190 ℃ for 5 minutes, cooling at 10 ℃/min to-10 ℃, keeping at-10 ℃ for 5 minutes, and raising the temperature at 10 ℃/min to 190 ℃. At this time, the melting point is the peak top temperature of the melting peak appearing in the above-described second melting curve. When 2 or more melting peaks were observed, the melting point was defined as the peak top temperature of the melting peak having the largest peak top height. It should be noted that the melting peak appearing in the DSC second melting curve of the crystalline polypropylene is generally a curve under the peak foot on the low temperature side which is gently elongated, and that a straight line drawn so that the base line on the high temperature side shown in FIG. 1 in the reading method of the 9.DTA or DSC curve of JIS K7121-1987 is extended to the low temperature side coincides with a straight line extending the base line on the same low temperature side to the high temperature side.

Further, according to JIS K7121-1987, the melting point of the above-mentioned polyolefin elastomer of component (B) was calculated by using a differential scanning calorimeter "Diamond DSC" (trade name) of Perkinelmer, by a second melting curve (melting curve measured during the final temperature rise) measured by keeping at 190 ℃ for 5 minutes, cooling at 10 ℃/min to-50 ℃, keeping at-50 ℃ for 5 minutes, and warming at 10 ℃/min to 190 ℃. At this time, the melting point is the peak top temperature of the melting peak appearing in the above-described second melting curve. When 2 or more melting peaks were observed, the melting point was defined as the peak top temperature of the melting peak having the largest peak top height. In addition, it should be noted that the melting peak appearing in the DSC second melting curve of the elastomer, usually the curve under the peak leg, is gently elongated on both the high temperature side and the low temperature side, and that drawing a base line makes a straight line extending from the base line on the high temperature side to the low temperature side shown in fig. 1 in the method of reading the 9.DTA or DSC curve of JIS K7121-1987 coincide with a straight line extending from the base line on the same low temperature side to the high temperature side.

(iv) Enthalpy of fusion

The enthalpy of fusion of the base film for dicing film was calculated from the DSC first melting curve obtained by the measurement of the melting point of the above (iii).

Further, the enthalpy of fusion of the crystalline polypropylene of the component (a) and the polyolefin elastomer of the component (B) is calculated from a DSC second melting curve obtained by measuring the melting point of the component (iii).

(v) Tensile test

According to JIS K7127:1999, a sample was punched from a film into the shape of the test piece type 5 (FIG. 2 of the JIS standard) of the above-mentioned standard using a tensile tester "AUTOGRAPHAGS-1 kNG" (trade name) manufactured by Shimadzu corporation so that the machine direction of the film was the tensile direction, and a tensile test was performed under the conditions of a tensile speed of 200mm/min and a temperature of 23 ℃ to obtain a stress-strain curve in the machine direction (hereinafter, simply referred to as "SS curve"). The transverse SS curve was obtained by the same measurement except that the sample was punched so that the transverse direction (direction orthogonal to the machine direction) of the film was the stretching direction.

(v-1) tensile modulus of elasticity

Regardless of how the calculation of item 10 of JIS K7127:1999 and the presentation of the results are defined, the machine direction tensile elastic modulus (described as "tensile elastic modulus MD" in the table) was calculated from the machine direction SS curve obtained in the above (v) tensile test by a method of obtaining the slope based on 2 points of item 10.3.2 of JIS K7161-1:2014 and by a method of obtaining the machine direction SS curve with σ 1 as the stress (MPa) in which strain ∈ 1 becomes 0.8% and σ 2 as the stress (MPa) in which strain ∈ 2 becomes 1.6%, regardless of how the item 10.3.2 of JIS K7161-1:2014 is defined. Similarly, the tensile modulus in the transverse direction (referred to as "tensile modulus TD" in the table) was calculated from the transverse direction SS curve obtained in the tensile test (v) above. The ratio of the machine-direction tensile modulus of elasticity to the transverse-direction tensile modulus of elasticity (machine-direction tensile modulus of elasticity/transverse-direction tensile modulus of elasticity.) was calculated.

(v-2) stress Difference (. DELTA.. sigma.)

According to item 10.1 of JIS K7161-1:2014, the tensile yield stress (σ y) is regarded as the stress in the tensile yield strain (∈ y) by the SS curve in the machine direction obtained by the tensile test (v) (in this case, attention is paid to annex a of the JIS standard), the tensile yield stress (σ y) and the tensile yield stress (σ 1) are calculated as the stress in the strain (∈ 1), and the stress difference in the machine direction (Δ σ ═ σ y — σ 1) is calculated (described as "stress difference MD" in the table). Similarly, the stress difference in the transverse direction (referred to as "stress difference TD" in the table) was calculated from the transverse direction SS curve obtained in the tensile test (v) above.

(v-3) 5% Strain tensile stress, 100% Strain tensile stress

The machine direction 5% strain tensile stress (referred to as "5% modulus MD" in the table) and the machine direction 100% strain tensile stress (referred to as "100% modulus MD" in the table) were calculated from the machine direction SS curve obtained by the tensile test (v) according to JIS K7161-1:2014 under item 10.1. Similarly, the transverse direction SS curve obtained by the tensile test (v) described above was used to calculate the transverse direction 5% strain tensile stress (referred to as "5% modulus TD" in the table) and the transverse direction 100% strain tensile stress (referred to as "100% modulus TD" in the table). The ratio of the machine direction 5% strain tensile stress to the transverse direction 5% strain tensile stress (machine direction 5% strain tensile stress/transverse direction 5% strain tensile stress, shown in the table as "5% modulus MD/TD") was calculated. Similarly, the ratio of the machine direction 100% strain tensile stress to the transverse direction 100% strain tensile stress (machine direction 100% strain tensile stress/transverse direction 100% strain tensile stress, reported as "100% modulus MD/TD") was calculated.

In the stretching process of the dicing, the ratio of the machine direction 5% strain tensile stress to the transverse direction 5% strain tensile stress may be usually 0.7 to 1.3, preferably 0.8 to 1.2, and more preferably 0.9 to 1.1, from the viewpoint of uniformly stretching the film. In the stretching process of the dicing, the ratio of the machine direction 100% strain tensile stress to the transverse direction 100% strain tensile stress may be usually 0.7 to 1.3, preferably 0.8 to 1.2, and more preferably 0.9 to 1.1, from the viewpoint of uniformly stretching the film.

(vi) Arithmetic average roughness (Ra) of matt surface

The arithmetic average roughness (Ra) of the matte surface was measured in accordance with JIS B0601:2013 using a precision roughness meter "HANDYSURFE-40A" (trade name) manufactured by Tokyo K.K.

(vii) Blocking resistance

■ determination of blocking resistance method (1)

2 samples having a size of 30cm in the machine direction and 10cm in the transverse direction were collected from a film having a matte side on one side and a glossy side on the other side, the matte side of 1 sample and the glossy side of the other sample were superposed so that the respective pieces of the 2 samples were substantially aligned, the sample was sandwiched between 2 metal plates of 30cm × 10cm, the sample was laid flat so that the respective pieces of the 2 samples superposed on the 2 metal plates were substantially aligned, a 1kg weight was placed thereon, and the sample was treated at 25 ℃ for 48 hours. Then, the 90 ° peel force of 2 samples was measured under the conditions that the test speed was 300 mm/min and the machine direction of the samples was parallel to the peeling direction. In the table, "< 0.1" means that the 90 ° peel force is less than 0.1N/10 cm. The 90 DEG peeling force may be preferably 0.5N/10cm or less, more preferably 0.3N/cm or less, from the viewpoint of blocking resistance. The smaller the above 90 ° peel force, the better.

■ determination of blocking resistance (2)

The 90 ° peel force of 2 samples was measured by the same method as described above except that the dimensions of the sample were changed to a size of 20cm in the machine direction and 10cm in the transverse direction so that the matte surface and the matte surface or the glossy surface were overlapped, the load by weight was changed to 6kg, the aging condition was changed to 80 ℃ for 5 hours, and the test speed was changed to 50 mm/min for the film having the matte surface on one side and the matte surface or the glossy surface on the other side and subjected to corona surface treatment on both sides.

■ determination of blocking resistance (3)

A film having a matte surface on one side and a matte or glossy surface on the other side and having no corona surface treatment or corona surface treatment on both sides was wound into a roll shape with a roll width of 10 inches (25.4cm) while applying a tension of 2 kg. After leaving at 40 ℃ for 1 week, the rolled film was measured for peel strength at a test speed of 200mm/min at which the film was pulled out from the core at a position of 10m in the longitudinal direction.

(viii) Solvent resistance

3 drops of toluene were dropped onto a matte surface (a surface on the embossing roll side in film formation, and a surface on the air chamber side in example 2) by using a dropper, and then the resultant was left to stand at 25 ℃ under an atmosphere having a relative humidity of 50% for 24 hours (the dropped toluene was dried). Then, the glossiness (60-degree glossiness) of the toluene dropped portion was measured by the method of the above test (ii). The difference between the gloss at the toluene dropping site and the gloss at the matte surface (hereinafter, sometimes referred to as "gloss difference", which is the gloss at the toluene dropping site — the gloss at the matte surface) was calculated. When the solvent resistance is low, the gloss of the dropping portion of toluene is lowered by roughening the surface or the unevenness of the surface is melted and raised. Therefore, the above-mentioned difference in glossiness may be preferably-3 to 3%, more preferably-2 to 2%, and still more preferably-1 to 1% from the viewpoint of solvent resistance. The smaller the absolute value of the above-mentioned difference in glossiness, the better.

Raw materials used

(A) Crystalline polypropylene

(A-1) Block Polypropylene "NOVATEC BC5 FA" (trade name) available from Japan Polypropylene corporation. MFR3.5g/10min, melting point 162 ℃, melting enthalpy 76J/g.

(A-2) a block polypropylene "VB 170A" (trade name) available from SunAllomer K.K.. MFR0.4g/10min, melting point 164 ℃, melting enthalpy 77J/g, 149 ℃ with melting shoulder.

(A-3) a block polypropylene "VB 370A" (trade name) available from SunAllomer K.K.. MFR1.5g/10min, melting point 164 ℃, melting enthalpy 80J/g, 148 ℃ has melting shoulder.

(A-4) A block polypropylene "PM 870A" (trade name) available from SunAllomer K.K.. MFR17.0g/10min, melting point 164 ℃ and melting enthalpy 87J/g.

(A-5) random Polypropylene "PRIMELYPROS 235 WC" (trade name) from PrimePolymer, Inc. MFR11.0g/10min, melting point 134 ℃, melting enthalpy 66J/g.

(A-6) homopolymer polypropylene "PL 500A" (trade name) available from SunAllomer K.K.. MFR3.0g/10min, melting point 162 ℃ and melting enthalpy 104J/g.

(A-7) homopolymer polypropylene "PM 600A" (trade name) available from SunAllomer K.K.. MFR7.5g/10min, melting point 163 ℃, melting enthalpy 102J/g.

(B) Polyolefin elastomer

(B-1) copolymer of propylene and 4-methyl-1-pentene (polyolefin elastomer "ABSORTOMEREP-1001" (trade name) available from Mitsui chemical Co., Ltd.). By passing¹³The amount of the structural unit derived from propylene was 28.1 mol% and the amount of the structural unit derived from 4-methyl-1-pentene was 71.9 mol% as determined by C-NMR. No melting peak was observed on the DSC second melting curve. MFR (230 ℃, 21.18N)10g/10 min.

(B-2) polyolefin elastomer "ABSORTOMEREP-1013" (trade name) available from Mitsui chemical Co., Ltd. MFR (230 ℃, 21.18N)10 g/10min, melting point 130 ℃, and enthalpy of fusion 11J/g.

(B-3) polyolefin elastomer "TAFTHRENH 3712D" (trade name) available from Sumitomo chemical Co., Ltd. A propylene/butene-1 random copolymer (the proportion of butene-1 is 10% by mass or less). The mass ratio of crystalline polypropylene regions to amorphous polypropylene regions is 15: 85. Melting point 131 ℃ and melting enthalpy 14J/g.

(B-4) EPDM "NORDELIP 3720P" (trade name) from Dow Elastomers. Melting point 34 ℃ and melting enthalpy 41J/g.

(B-5) polyolefin elastomer "TAFTHRENT 3732" (trade name) available from Sumitomo chemical Co., Ltd. A propylene/butene-1 random copolymer (containing 5 mass% of butene-1). The mass ratio of crystalline polypropylene regions to amorphous polypropylene regions is 50: 50. Melting point 129 ℃ and melting enthalpy 32J/g.

Example 1

A resin mixture of 100 parts by mass of the component (A-1) and 18 parts by mass of the component (B-1) was continuously extruded from a T-die 2 as a molten film 3 using a film forming apparatus shown in FIG. 5 (the film forming apparatus was equipped with an extruding apparatus having an extruder 1 and a T-die 2, and a drawing and winding apparatus having a mechanism sandwiched between a smooth roll (mirror metal roll) as a first roll 4 and an embossing roll (satin rubber roll: surface arithmetic average roughness (Ra) of 1.5 μm, ten-point average roughness (Rz) of 11.9 μm) as a second roll 5). Next, the extruded molten film 3 is fed between the rotating first roll 4 and the rotating second roll 5, and is molded by the first roll 4 and the second roll 5. Then, the first roll 4 was fed to the next rotating roll 6 with the molten film 3 being molded, and a film 7 having a thickness of 100 μm was formed. At this time, the T-die exit resin temperature was 210 ℃, the surface temperature of the first roll 4 was 25 ℃, the cooling water temperature to the second roll 5 was 16 ℃ and the take-up speed was 18 m/min. The above-mentioned tests (i) to (viii) were carried out. Test (vii) blocking resistance was measured by the measurement method (1). The results are shown in Table 1.

Example 2

A film having a thickness of 100 μm was formed using a resin mixture of 100 parts by mass of the component (A-1) and 18 parts by mass of the component (B-1) by using a film forming apparatus equipped with an extrusion apparatus having an extruder 1 and a T-die 2 and a take-up apparatus having a mirror-surface metal roll (chill roll) and an air chamber, under the conditions of a T-die exit resin temperature of 220 ℃, a surface temperature of the mirror-surface metal roll (chill roll) of 25 ℃ and a take-up speed of 18 m/min. The above-mentioned tests (i) to (viii) were carried out. Test (vii) blocking resistance was measured by the measurement method (1). The results are shown in Table 1.

Examples 3 to 19

Film formation and measurement and evaluation of physical properties were carried out in the same manner as in example 1 except that the resin mixture shown in any 1 of tables 1 to 4 was used. The results are shown in any one of tables 1 to 4.

[ TABLE 1]

[ TABLE 2]

[ TABLE 3 ]

[ TABLE 4]

The film of the present invention can be preferably produced by the production method of the present invention. The preferred film of the present invention is excellent in heat resistance, flexibility, transparency, solvent resistance and blocking resistance, and has stretching characteristics suitable for the stretching process. Therefore, it can be preferably used as a dicing film base film.

The haze (measured according to JIS K7136:2000 using a haze meter "NDH 2000" (trade name) manufactured by Nippon Denshoku Kogyo Co., Ltd.) of the base film of example 1 was 84.8% (direct output value of the haze meter). Then, a coating material for forming an adhesive layer, which was composed of 333 parts by mass (in terms of solid content, 100 parts by mass) of a transparent adhesive "ACRYBASELKG-1013" (trade name) produced by Teng Kabushiki Kaisha, 1 part by mass of an isocyanate curing agent "CL-201" (trade name) produced by Teng Kabushiki Kaisha, and 222 parts by mass of ethyl acetate, was applied onto the matte surface of the base film of example 1 using an applicator, and the film thickness after drying was 10 μm. Subsequently, the coating film was dried at a temperature of 85 ℃ to form an adhesive layer, and a dicing film was obtained. The cut film had a haze (measured according to JIS K7136:2000 using a haze meter "NDH 2000" (trade name) manufactured by Nippon Denshoku industries Co., Ltd.) of 11.0%. It was confirmed that the formation of the adhesive layer on the matte surface eliminated the haze on the exterior due to the unevenness of the matte surface, and ensured sufficient transparency as a dicing film.

Optimization experiment of matte surface treatment conditions in corona surface treatment

Example 20

Using a resin mixture of 70 parts by mass of the above-mentioned component (A-1) and 30 parts by mass of the above-mentioned component (B-5), a film forming apparatus equipped with a rubber embossing roll having an arithmetic average roughness (Ra) of 0.5 μm instead of the rubber embossing roll having an arithmetic average roughness (Ra) of 1.5 μm as the second roll 5 was used, and the take-up speed was changed from 18 m/min to 5 m/min, and a corona treatment power supply "AGI-020" manufactured by a spring motor (Ltd., discharge rate was 0.20kW ■ min/m²The film was formed in the same manner as in example 1 except that both sides of the obtained film were subjected to corona surface treatment so that the wetting tension of the corona surface-treated side of the film measured in accordance with JIS K6768:1999 was 50mN/m or more, and the blocking resistance of the film was measured by the measurement method (2) of the above-mentioned (vii). 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 used and the amount of discharge for the corona surface treatment are also the same in the following examples.

Example 21

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-mentioned component (A-1) and 30 parts by mass of the above-mentioned component (B-5) was used and both surfaces of the obtained film were subjected to corona surface treatment, and the blocking resistance of the film was measured by the above-mentioned measurement method (2) of (vii). That is, film formation and physical property measurement of a thin film were performed in the same manner as in example 20 except that the rubber embossing roll having an arithmetic average roughness (Ra) of 1.5 μm was not changed as the second roll 5 in example 1. The results are shown in Table 5.

Example 22

The 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, a film forming apparatus equipped with a satin-grained embossing roll made of metal having an arithmetic average roughness (Ra) of 0.5 μm as the first roll 4 instead of a smooth roll (mirror-surface metal roll) and a rubber-grained embossing roll having an arithmetic average roughness (Ra) of 0.5 μm as the second roll 5 was used, and both surfaces of the obtained film were subjected to corona surface treatment, and the blocking resistance of the film was measured by the measurement method (2) of the above (vii). That is, film formation and physical property measurement of a thin film were carried out in the same manner as in example 20 except that an embossing roll having an arithmetic average roughness (Ra) of 0.5 μm was further used as the first roll 4 instead of the smoothing roll. The results are shown in Table 5.

Example 23

The blocking resistance was measured by the measurement method (2) of the above (vii) on the film formed by 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 by using a film forming apparatus equipped with a satin embossing roller made of metal having an arithmetic average roughness (Ra) of 0.5 μm as the first roller 4, and by forming a film by corona surface treatment on both sides of the obtained film in the same manner as in example 1. That is, film formation and physical properties measurement of a thin film were carried out in the same manner as in example 22 except that one embossing roll having an arithmetic average roughness (Ra) of 0.5 μm was replaced with another embossing roll having an arithmetic average roughness (Ra) of 1.5 μm. The results are shown in Table 5.

[ TABLE 5]

From the results shown in table 5, it is understood that the larger the arithmetic average roughness (Ra) of the embossing roller used for the matte surface treatment, that is, the deeper the depth of the emboss transcribed to the film surface, the more effectively blocking can be suppressed. Further, it is found that blocking can be more effectively suppressed by performing matte surface treatment on both sides of the film than by performing matte surface treatment on only one side.

Optimization experiment of film composition/Presence of Corona surface treatment/matte 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-mentioned component (A-1) and 30 parts by mass of the above-mentioned component (B-5) was used, and the blocking resistance of the film was measured by the above-mentioned measuring method (3) of (vii). The results are shown in Table 6.

Example 25

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 a film forming apparatus equipped with a satin embossing roll made of metal having an arithmetic average roughness (Ra) of 0.5 μm was used as the first roll 4 in place of the smooth roll (mirror surface metal roll), and the blocking resistance of the film was measured by the measurement method (3) of the above (vii). That is, film formation and physical properties measurement of a thin film were carried out in the same manner as in example 24 except that a metal embossing roll having an arithmetic average roughness (Ra) of 0.5 μm was used as the first roll 4 instead of the smooth roll (mirror-surface metal roll). The results are shown in Table 6.

Example 26

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-mentioned component (A-1) and 30 parts by mass of the above-mentioned component (B-5) was used and both surfaces of the obtained film were subjected to corona surface treatment, and the blocking resistance of the film was measured by the above-mentioned measurement method (3) of (vii). The results are shown in Table 6.

Example 27

The blocking resistance was measured by the measurement method (3) of the above (vii) on the film formed by 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 by using a film forming apparatus equipped with a satin embossing roller made of metal having an arithmetic average roughness (Ra) of 0.5 μm as the first roller 4, and by forming a film by corona surface treatment on both sides of the obtained film in the same manner as in example 1. That is, film formation and physical properties measurement of a thin film were carried out in the same manner as in example 26 except that a metal embossing roll having an arithmetic average roughness (Ra) of 0.5 μm was used as the first roll 4 instead of the smooth roll (mirror-surface metal roll). The results are shown in Table 6.

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-mentioned component (A-1) and 30 parts by mass of the above-mentioned component (B-1) was used and both surfaces of the obtained film were subjected to corona surface treatment, and the blocking resistance of the film was measured by the above-mentioned measurement method (3) of (vii). The results are shown in Table 6.

Example 29

The blocking resistance was measured by the measurement method (3) of the above (vii) on the film formed by 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-1) and by using a film forming apparatus equipped with a satin embossing roller made of metal having an arithmetic average roughness (Ra) of 0.5 μm as the first roller 4, and by forming a film by corona surface treatment on both sides of the obtained film in the same manner as in example 1. That is, film formation and physical properties measurement of a thin film were carried out in the same manner as in example 28 except that a metal embossing roll having an arithmetic average roughness (Ra) of 0.5 μm was used as the first roll 4 instead of the smooth roll (mirror-surface metal roll). The results are shown in Table 6.

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-mentioned component (A-1) and 30 parts by mass of the above-mentioned component (B-2) was used and both surfaces of the obtained film were subjected to corona surface treatment, and the blocking resistance of the film was measured by the above-mentioned measurement method (3) of (vii). The results are shown in Table 6.

Example 31

The blocking resistance was measured by the measurement method (3) of the above (vii) on the film formed by 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-2) and by using a film forming apparatus equipped with a satin embossing roller made of metal having an arithmetic average roughness (Ra) of 0.5 μm as the first roller 4, and by forming a film by corona surface treatment on both sides of the obtained film in the same manner as in example 1. That is, film formation and physical properties measurement of a thin film were carried out in the same manner as in example 30 except that a metal embossing roll having an arithmetic average roughness (Ra) of 0.5 μm was used as the first roll 4 instead of the smooth roll (mirror-surface metal roll). The results are shown in Table 6.

Example 32

The film was formed in the same manner as in example 1 except that the above-mentioned component (a-1) was used alone as a resin (a mixture with the component (B) was not used) and a film forming apparatus equipped with a satin embossing roller made of metal having an arithmetic average roughness (Ra) of 0.5 μm was used as the first roller 4 in place of a smooth roller (mirror metal roller), and the blocking resistance of the film was measured by the above-mentioned measurement method (3) of (vii). The results are shown in Table 6.

Example 33

The film was formed in the same manner as in example 1 except that the above-mentioned component (B-1) was used alone as a resin (a mixture with the component (A) was not used) and both sides of the obtained film were subjected to corona surface treatment, and the blocking resistance of the film was measured by the above-mentioned measurement method (3) of (vii). The results are shown in Table 6.

In addition, in examples 24 to 33, in table 6, the case where only one side of the film was subjected to the matte surface treatment is represented as "one side", and the case where both sides of the film were subjected to the matte surface treatment is represented as "both sides".

[ TABLE 6]

From the results shown in table 6, it was further confirmed that blocking could be more effectively suppressed by performing matte surface treatment on both sides of the film than by performing matte surface treatment on only one side (the same as table 5). Further, from these results, it is found that blocking can be effectively suppressed by performing matte surface treatment on both sides of the film even in the case of performing corona surface treatment on both sides.

Relationship between the mass ratio of amorphous polypropylene domains and the flexibility of the film

Example 34

A film was formed in the same manner as in example 1 except that a resin mixture of 70 parts by mass of the component (A-1) and 30 parts by mass of the component (B-5) was used in the same manner as in example 24, and the film thus formed was subjected to the tensile test of (v) to measure the tensile elastic modulus of (v-1), the stress difference (. DELTA.. sigma.), (v-2), the 5% strain tensile stress of (v-3) and the 100% strain tensile stress. The results are shown in Table 7.

Examples 35 to 41

As shown in Table 7, films were formed in the same manner as in example 34 except that the kinds and the amounts of the components (A) and (B) were changed, and the film thus formed was subjected to the above-mentioned tensile test (v) to measure the tensile elastic modulus (v-1), the stress difference (. DELTA.. sigma.), (v-2) the tensile stress at 5% strain, and the tensile stress at 100% strain. The results are shown in Table 7.

[ TABLE 7]

From the results shown in table 7, it is understood that the greater the mass ratio of the amorphous polypropylene region to the total mass of the components (a) and (B) contained in the base film for dicing film in the random copolymer as the component (B) (in the present example, the same mass ratio as the amorphous polypropylene region to the total mass of the base film for dicing film), the more excellent the flexibility of the film.

Description of the symbols

1: extruding machine

2: t-shaped matrix

3: fused film

4: first roller

5: second roll

6: rotating roller

7: film(s)