JP7791308B2 - Resin composition for backgrind film substrate, backgrind film substrate, and backgrind film - Google Patents

Description

The present invention relates to a resin composition for a backgrind film substrate, a backgrind film substrate, and a backgrind film.

In the manufacturing process of semiconductor devices such as ICs, a back-grinding process is typically performed to polish the backside of a semiconductor wafer with a circuit pattern formed on it in order to thin it. During the back-grinding process, an adhesive film (back-grinding film) is attached to the circuit pattern surface of the semiconductor wafer to protect it from contamination and to hold the thinned semiconductor wafer in place. After the back-grinding process, a stretchable wafer processing film (dicing film) is typically attached to the backside of the polished semiconductor wafer, and the dicing process is then performed to divide the semiconductor wafer into chips.

The surface of a semiconductor wafer is uneven because a circuit pattern is formed on it. Therefore, if the backgrinding film is not flexible, gaps will form between the semiconductor wafer surface and the backgrinding film, which could cause the semiconductor wafer and backgrinding film to peel off during backgrinding. For this reason, the backgrinding film must be flexible (able to conform to uneven surfaces) so that it can adhere to the semiconductor wafer even when uneven surfaces are present.

Furthermore, after the backgrinding process, the backgrind film is peeled off from the semiconductor wafer surface, but if part of the backgrind film remains on the semiconductor wafer surface during peeling, there is a risk of contaminating the semiconductor wafer. When part of the backgrind film remains on the semiconductor wafer, this is also known as adhesive residue. Therefore, the backgrind film must be easily releasable to prevent adhesive residue.

In addition, the backgrinding film must be resistant to deformation such as distortion or warping (heat shrinkage resistance) due to the frictional heat generated when polishing semiconductor wafers, the heat applied when applying adhesive to the backgrinding film base, and the heat applied when drying polishing debris after washing it with water.

As an example of a backgrind film substrate, ethylene-vinyl acetate copolymer (hereinafter sometimes abbreviated as EVA) is used because of its flexibility, releasability, and resistance to deformation.

For example, Patent Document 1 describes a back-grinding adhesive tape having a substrate film on which an adhesive layer for adhering and fixing wafers is provided, in which the substrate film is a single-layer film made of a mixture of 60 to 98% by weight of one or more ethylene-vinyl acetate copolymer resins having a vinyl acetate content of 15 to 30% by weight and 2 to 40% by weight of one or more polyolefin resins having a melting point of 100°C or higher. It also describes that this type of back-grinding adhesive tape has sufficient flexibility to prevent wafer damage during the wafer back-grinding process, and is heat-shrinkage resistant so that it does not easily shrink due to the heat experienced during each process.

Patent Document 2 also describes an adhesive film that contains 60 parts by weight of (A) ethylene-propylene-diene copolymer and 40 parts by weight of (B) ethylene-vinyl acetate copolymer, and that exhibits adhesiveness when heated to a temperature of 50 to 90°C. It also describes that such an adhesive film exhibits increased or decreased adhesiveness depending on the temperature conditions under which it is used, and can be easily peeled off by cooling.

Japanese Patent Application Laid-Open No. 2005-33000 Japanese Unexamined Patent Publication No. 2-129282

However, because EVA is highly flexible, chips and whiskers can be generated when cutting the backgrinding film into the shape of a semiconductor wafer. These chips and whiskers can contaminate the semiconductor wafer and have adverse effects on processes after the backgrinding process. In other words, there was a need for improved tearability.

In contrast, the adhesive film of Patent Document 2 is primarily composed of an ethylene-propylene-diene copolymer from the standpoint of film-forming properties, and therefore does not have sufficient flexibility. Furthermore, the base film of Patent Document 1, while primarily composed of EVA, also contains a polyolefin resin with a melting point of 100°C or higher, and therefore does not have sufficient flexibility. Furthermore, these documents make no mention of the reduced tear resistance that results from the high flexibility of EVA.

The present invention was made in consideration of the above-mentioned problems. It aims to provide a resin composition for a backgrind film substrate, a backgrind film substrate, and a backgrind film that can realize a backgrind film substrate that has excellent flexibility and tearability.

That is, the present invention provides the following resin composition for a backgrind film substrate.
[1] A resin composition for a backgrind film substrate, comprising: an ethylene-unsaturated ester copolymer (A); and at least one selected from the group consisting of an ethylene-α-olefin copolymer (B) having a melt flow rate of 0.1 g/10 min or more and less than 25 g/10 min, as measured in accordance with JIS K 7210:1999 at 190°C under a load of 2160 g, and a styrene-based resin (C), wherein the content of the ethylene-unsaturated ester copolymer (A) is more than 60 parts by mass and less than 100 parts by mass, when the total amount of the ethylene-unsaturated ester copolymer (A), the ethylene-α-olefin copolymer (B), and the styrene-based resin (C) is taken as 100 parts by mass.
[2] The resin composition for backgrind film substrates according to [1], wherein the content of structural units derived from unsaturated esters in the ethylene-unsaturated ester copolymer (A) is 15% by mass or more and 46% by mass or less.
[3] The ethylene-unsaturated ester copolymer (A) has a melt flow rate of 0.1 g/10 min or more and 100 g/10 min or less, measured in accordance with JIS K 7210:1999 at 190 ° C. under a load of 2160 g. [4] The resin composition for backgrind film substrates according to [1] or [2].
[4] The resin composition for a backgrind film substrate according to any one of [1] to [3], wherein the melting point of the ethylene/α-olefin copolymer (B) is less than 100°C.
[5] The styrene-based resin (C) has a melt flow rate of 0.01 g/10 min or more and 50 g/10 min or less, as measured at 190 ° C. under a load of 2160 g in accordance with JIS K 7210:1999. [6] The resin composition for backgrind film substrates according to any one of [1] to [4].
[6] The resin composition for a backgrind film substrate according to any one of [1] to [5], wherein the styrene-based resin (C) is a styrene-based elastomer.
[7] The resin composition for backgrind film substrate according to any one of [1] to [6], wherein the total amount of the ethylene-unsaturated ester copolymer (A), the ethylene-α-olefin copolymer (B), and the styrene-based resin (C) is 70% by mass or more and 100% by mass or less, when the entire resin composition for backgrind film is 100% by mass.
[8] The resin composition for a backgrind film substrate according to any one of [1] to [7], wherein the ethylene-unsaturated ester copolymer (A) is an ethylene-vinyl acetate copolymer.

The present invention provides the following backgrind film substrate and backgrind film.
[9] A backgrind film substrate having at least one layer containing the resin composition for backgrind film substrates according to any one of [1] to [8].
[10] The backgrind film substrate according to [9], wherein the layer containing the resin composition for the backgrind film substrate has an initial hardness (Shore A) measured in accordance with JIS K 7215:1996 of 75 or less.
[11] The layer containing the resin composition for the backgrind film substrate has a hardness (Shore A) measured in accordance with JIS K 7215:1996, 15 seconds after the start of measurement, of 72 or less. [9] or [10] The backgrind film substrate.
[12] A backgrind film comprising the backgrind film substrate according to any one of [9] to [11] and an adhesive layer laminated on at least one surface of the backgrind film substrate.

The resin composition for backgrind film substrate of the present invention enables the production of a backgrind film substrate that is excellent in flexibility and tearability.

In this specification, numerical ranges expressed using "to" refer to a range that includes the numerical values before and after "to" as the lower and upper limits. Furthermore, "(meth)acrylic acid" is a notation that encompasses both "acrylic acid" and "methacrylic acid," and "(meth)acrylate" is a notation that encompasses both "acrylate" and "methacrylate."

1. Resin composition for backgrind film substrate The resin composition for backgrind film substrate of the present invention (hereinafter also simply referred to as "resin composition") is mainly used for the substrate of backgrind film, but the use of the resin composition is not limited to the substrate of backgrind film.

As mentioned above, the substrate of a backgrind film must not only be flexible enough to conform to the irregularities on the surface of a semiconductor wafer, but also must have improved tearability so that chips and whiskers are not generated when the substrate is cut to the shape of a semiconductor wafer.

In response to this, the inventors conducted extensive research and found that a resin composition comprising an ethylene-unsaturated ester copolymer (A), an ethylene-α-olefin copolymer (B) having a melt flow rate of 0.1 g/10 min or more but less than 25 g/10 min, as measured at 190°C under a load of 2,160 g, and at least one selected from a styrene-based resin (C), wherein the content of the ethylene-unsaturated ester copolymer (A) is more than 60 parts by mass but less than 100 parts by mass, when the total amount of the ethylene-unsaturated ester copolymer (A), the ethylene-α-olefin copolymer (B), and the styrene-based resin (C) is taken as 100 parts by mass, can maintain flexibility while improving tear resistance.

The reason for this is believed to be as follows: Because ethylene-unsaturated ester copolymers (A), such as EVA, have high flexibility, they are prone to producing chips and whiskers when a layer containing a resin composition containing them is cut into the shape of a semiconductor wafer. In contrast, ethylene-α-olefin copolymers (B) with low melt flow rates and styrene-based resins (C) with relatively rigid structures are highly compatible with ethylene-unsaturated ester copolymers (A) and can impart appropriate strength to the resin composition. This can improve tear resistance while maintaining the high flexibility inherent in the ethylene-unsaturated ester copolymer (A), and is thought to suppress the production of chips and whiskers when cutting into a predetermined shape.

As described above, the resin composition of the present application comprises an ethylene-unsaturated ester copolymer (A) and at least one selected from an ethylene-α-olefin copolymer (B) and a styrene-based resin (C).

In the above resin composition, when the total amount of the ethylene-unsaturated ester copolymer (A), ethylene-α-olefin copolymer (B), and styrene-based resin (C) is taken as 100 parts by mass, the content of the ethylene-unsaturated ester copolymer (A) is more than 60 parts by mass but less than 100 parts by mass, preferably 65 parts by mass or more but 95 parts by mass or less, more preferably 70 parts by mass or more but 90 parts by mass or less, and even more preferably 75 parts by mass or more but 85 parts by mass or less. When the content of the ethylene-unsaturated ester copolymer (A) is at least the lower limit, the flexibility of the resin composition is more likely to be increased, and when it is at most the upper limit, the tearability of the resin composition is less likely to be impaired.

In the above resin composition, when the total amount of the ethylene-unsaturated ester copolymer (A), the ethylene-α-olefin copolymer (B), and the styrene-based resin (C) is taken as 100 parts by mass, the total amount of the ethylene-α-olefin copolymer (B) and the styrene-based resin (C) is more than 0 parts by mass but less than 40 parts by mass, preferably 5 parts by mass or more but 35 parts by mass or less, more preferably 10 parts by mass or more but 30 parts by mass or less, and even more preferably 15 parts by mass or more but 25 parts by mass or less. When the total amount of the ethylene-α-olefin copolymer (B) and the styrene-based resin (C) is equal to or greater than the lower limit, the tear resistance of the resin composition is further improved, and when it is equal to or less than the upper limit, the flexibility of the resin composition is less likely to be impaired.

The total amount of the ethylene-unsaturated ester copolymer (A), ethylene-α-olefin copolymer (B), and styrene-based resin (C) in the above resin composition is not particularly limited, but when the entire resin composition is taken as 100% by mass, it is preferably 70% by mass or more and 100% by mass or less, more preferably 80% by mass or more and 100% by mass or less, even more preferably 90% by mass or more and 100% by mass or less, particularly preferably 95% by mass or more and 100% by mass or less, especially preferably 98% by mass or more and 100% by mass or less, and extremely preferably 99% by mass or more and 100% by mass or less.

Below, we will explain each component contained in the resin composition, and then explain the physical properties of the resin composition.

<Ethylene-Unsaturated Ester Copolymer (A)>
The ethylene-unsaturated ester copolymer (A) is a polymer obtained by copolymerizing ethylene with an unsaturated ester.

Examples of unsaturated esters include vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, and vinyl stearate; and unsaturated carboxylic acid esters such as alkyl (meth)acrylates. Of these, vinyl esters are preferred, and vinyl acetate is more preferred.

That is, the ethylene-unsaturated ester copolymer (A) is preferably, for example, an ethylene-vinyl acetate copolymer, an ethylene-vinyl propionate copolymer, an ethylene-vinyl butyrate copolymer, or an ethylene-vinyl stearate copolymer, and more preferably an ethylene-vinyl acetate copolymer.

The content of ethylene-derived structural units in the ethylene-unsaturated ester copolymer (A) is preferably 54% by mass or more and 85% by mass or less, more preferably 58% by mass or more and 80% by mass or less, even more preferably 62% by mass or more and 74% by mass or less, particularly preferably 65% by mass or more and 72% by mass or less, and especially preferably 66% by mass or more and 69% by mass or less, based on the total structural units of the ethylene-unsaturated ester copolymer (A). When the content of ethylene-derived structural units is equal to or greater than the lower limit, the resin composition does not become too soft, further reducing stickiness, adhesive residue, and the like. When the content of ethylene-derived structural units is equal to or less than the upper limit, the flexibility of the resin composition is less likely to be impaired.

The content of structural units derived from unsaturated esters in the ethylene-unsaturated ester copolymer (A) is preferably 15% by mass or more and 46% by mass or less, more preferably 20% by mass or more and 42% by mass or less, even more preferably 26% by mass or more and 38% by mass or less, particularly preferably 28% by mass or more and 35% by mass or less, and especially preferably 31% by mass or more and 34% by mass or less, based on the total structural units of the ethylene-unsaturated ester copolymer (A). When the content of structural units derived from unsaturated esters is equal to or greater than the lower limit, the flexibility of the resin composition is further enhanced, and when used as a backgrind film substrate, the resin composition's ability to conform to uneven surfaces is further enhanced. When the content of structural units derived from unsaturated esters is equal to or less than the upper limit, the resin composition is further suppressed from stickiness, adhesive residue, etc.

The ethylene-unsaturated ester copolymer (A) may further contain structural units derived from monomers other than ethylene and unsaturated esters. Examples of such other monomers include olefins such as propylene, butene, and hexene.

The melt flow rate of the ethylene-unsaturated ester copolymer (A), measured in accordance with JIS K 7210:1999 at 190°C under a load of 2160 g, is preferably 0.1 g/10 min to 100 g/10 min, more preferably 1 g/10 min to 70 g/10 min, even more preferably 15 g/10 min to 50 g/10 min, and particularly preferably 25 g/10 min to 35 g/10 min. When the melt flow rate of the ethylene-unsaturated ester copolymer (A) is equal to or greater than the lower limit, the flexibility of the resin composition is further enhanced, and the resin composition's ability to conform to uneven surfaces when used as a backgrind film substrate is further enhanced. When the melt flow rate of the ethylene-unsaturated ester copolymer (A) is equal to or less than the upper limit, the resin composition is further prevented from sticking or leaving adhesive residue.

The ethylene-unsaturated ester copolymer (A) may be used alone or in combination of two or more types.

The method for producing the ethylene-unsaturated ester copolymer (A) according to this embodiment is not particularly limited, and it can be produced by a known method. For example, it can be obtained by radical copolymerization of the respective polymerization components under high temperature and high pressure. Alternatively, commercially available ethylene-unsaturated ester copolymers (A) may be used.

<Ethylene/α-olefin copolymer (B)>
The ethylene/α-olefin copolymer (B) is a copolymer of ethylene and an α-olefin having 3 or more carbon atoms.

Preferably, the α-olefin has 3 to 20 carbon atoms. Examples of α-olefins having 3 to 20 carbon atoms include linear α-olefins such as propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nanodecene, and 1-eicosene; and branched α-olefins such as 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 2-ethyl-1-hexene, and 2,2,4-trimethyl-1-pentene. These α-olefins may be used alone or in combination of two or more. Among these, the number of carbon atoms of the α-olefin is preferably 3 to 10 from the viewpoint of versatility (cost, mass productivity, and ease of availability), and more preferably 4 to 8 from the viewpoint of preventing a decrease in the flexibility of the resin composition.

The ethylene/α-olefin copolymer (B) is preferably an ethylene/propylene copolymer, an ethylene/1-butene copolymer, an ethylene/4-methyl-1-pentene copolymer, an ethylene/1-hexene copolymer, or an ethylene/1-octene copolymer, and from the viewpoint of better maintaining the flexibility of the resin composition, an ethylene/1-butene copolymer is more preferred.

When the content of all structural units constituting the ethylene/α-olefin copolymer (B) is taken as 100% by mass, the content of structural units derived from α-olefins is preferably 5% by mass or more but less than 50% by mass, more preferably 10% by mass or more but less than 40% by mass, and even more preferably 10% by mass or more but less than 30% by mass. When the content of structural units derived from α-olefins is within the above range, the flexibility of the resin composition is less likely to be impaired.

The melt flow rate of the ethylene/α-olefin copolymer (B), measured in accordance with JIS K 7210:1999 at 190°C under a load of 2160 g, is 0.1 g/10 min or more but less than 25 g/10 min, preferably 0.3 g/10 min or more but less than 15 g/10 min, more preferably 0.5 g/10 min or more but less than 10 g/10 min, and even more preferably 0.7 g/10 min or more but less than 5 g/10 min. When the melt flow rate of the ethylene/α-olefin copolymer (B) is equal to or greater than the lower limit, the flexibility of the resin composition is less likely to be impaired. When the melt flow rate of the ethylene/α-olefin copolymer (B) is equal to or less than the upper limit, the resin composition can be imparted with adequate strength, which makes it easier to further improve tear resistance.

The density of the ethylene/α-olefin copolymer (B), measured in accordance with JIS K7112:1999, is preferably 840 kg/m ³ or more and 930 kg/m ³ or less, more preferably 850 kg/m ³ or more and 910 kg/m ³ or less, particularly preferably 860 kg/m ³ or more and 890 kg/m ³ or less, and particularly preferably 865 kg/m ³ or more and 880 kg/m ³ or less.

The melting point of the ethylene/α-olefin copolymer (B) is preferably less than 100°C, more preferably 90°C or less, even more preferably 80°C or less, and particularly preferably 70°C or less. When the melting point of the ethylene/α-olefin copolymer (B) is within the above range, the flexibility of the resin composition is maintained well while the tear resistance is easily further improved. The melting point of the ethylene/α-olefin copolymer (B) can be measured in accordance with JIS K 7121 (1987), for example, using a differential scanning calorimeter (DSC) or the like.

The melting point of the ethylene/α-olefin copolymer (B) can be adjusted, for example, by the type and content of the α-olefin. For example, the larger the carbon number of the α-olefin constituting the ethylene/α-olefin copolymer (B) and the higher the content, the lower the melting point of the ethylene/α-olefin copolymer (B) tends to be.

The ethylene/α-olefin copolymer (B) may be used alone or in combination of two or more.

<Styrene-based resin (C)>
The styrene-based resin (C) may be any resin having at least styrene as a constituent unit, and may be a homopolymer of styrene or a polymer of styrene and another monomer. Examples of the styrene-based resin (C) include styrene-based elastomers, ABS-based resins which are copolymers of acrylonitrile and styrene, polystyrene, etc. Among these, styrene-based elastomers are preferred. The styrene-based elastomer refers to a styrene-based polymer which is a rubbery elastic body at room temperature.

Examples of styrene-based elastomers include block copolymers containing hard segments consisting of styrene blocks (styrene polymers) and soft segments consisting of alkylene blocks, or hydrogenated products thereof; random copolymers of styrene and alkylene, or hydrogenated products thereof; or acid-modified styrene-based elastomers obtained by acid-modifying such styrene-based elastomers.

In the above block copolymer, the styrene block may be a portion formed by polymerizing two or more styrenes, and the alkylene block may be a portion formed by polymerizing two or more alkenes. The alkylene block may be a homopolymer of one type of alkene, or a copolymer of two or more types of alkenes.

Examples of the above block copolymers include styrene-butadiene block copolymer (SB), styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene block copolymer (SI), and styrene-isoprene-styrene block copolymer (SIS).

As mentioned above, the styrene-based elastomer may be a hydrogenated product of the above-mentioned block copolymer. In such a hydrogenated product, both the styrene block and the alkylene block may be hydrogenated, or only either the styrene block or the alkylene block may be hydrogenated, or only a portion of the styrene block and the alkylene block may be hydrogenated.

Examples of hydrogenated products of the above block copolymers include styrene-ethylene-butylene block copolymer (SEB), which is a hydrogenated product of styrene-butadiene block copolymer (SB), styrene-ethylene-butylene-styrene block copolymer (SEBS), which is a hydrogenated product of styrene-butadiene-styrene block copolymer (SBS), and styrene-ethylene-propylene-styrene block copolymer (SEPS), which is a hydrogenated product of styrene-isoprene-styrene block copolymer (SIS).

As mentioned above, examples of styrene-based elastomers include random copolymers of styrene and alkylenes. Examples include styrene-butadiene random copolymers, styrene-isoprene random copolymers, styrene-ethylene-butylene random copolymers, styrene-ethylene-propylene random copolymers, styrene-isobutylene random copolymers, and styrene-ethylene-isoprene random copolymers.

As mentioned above, the styrene-based elastomer may be a hydrogenated product of the above random copolymer. Examples include hydrogenated styrene-butadiene random copolymer (HSBR).

Among the non-acid-modified styrene-based elastomers listed above, hydrogenated products are preferred, with styrene-ethylene-butylene-styrene block copolymer (SEBS) and styrene-ethylene-propylene-styrene block copolymer (SEPS) being more preferred, with styrene-ethylene-butylene-styrene block copolymer (SEBS) being particularly preferred from the viewpoint of achieving good tearability without impairing the flexibility of the backgrind film substrate obtained from the resin composition.

On the other hand, the styrene-based elastomer may be an acid-modified styrene-based elastomer in which the above-mentioned block copolymer or random copolymer, or an elastomer composed of a hydrogenated product thereof, is graft-modified with an unsaturated carboxylic acid or a derivative thereof, as described above. The acid-modified styrene-based elastomer may be an elastomer in which the above-mentioned block copolymer or random copolymer, or an elastomer composed of a hydrogenated product thereof, is graft-modified with one unsaturated carboxylic acid or a derivative thereof, or with two or more unsaturated carboxylic acids or derivatives thereof.

Examples of unsaturated carboxylic acids used for graft modification include (meth)acrylic acid, 2-ethylacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, etc. On the other hand, examples of unsaturated carboxylic acid derivatives used for graft modification include acid anhydrides such as maleic anhydride, phthalic anhydride, and itaconic anhydride; acid esters such as monomethyl maleate and monoethyl maleate; acid amides; acid halides; etc. Of these, maleic acid or maleic anhydride is preferred from the standpoint of reactivity with styrene-based elastomers, etc.

Acid-modified styrene-based elastomers are obtained by graft polymerizing the above-mentioned block copolymers, random copolymers, etc. with an unsaturated carboxylic acid or its derivative in the presence of a radical initiator. Any known radical initiator can be used as long as it is used in the graft reaction of polyolefins.

The acid value of the acid-modified styrene elastomer is preferably more than 0 mg CH ₃ ONa/g and less than 20 mg CH ₃ ONa/g, more preferably more than ₀ mg CH ₃ ONa/g and less than 11 mg CH 3 ONa/g, and even more preferably 0.5 mg CH ₃ ONa/g to 11 mg CH ₃ ONa/g.

Furthermore, examples of styrene-based resins (C) include ABS-based resins. ABS-based resins are resins containing acrylonitrile-derived structural units and styrene-derived structural units, and examples include rubber-reinforced styrene-based polymers synthesized by various manufacturing methods such as blending, grafting, or graft-blending. Specific examples of ABS resins include those obtained by graft-polymerizing rubber components such as polybutadiene, styrene-butadiene rubber, and ethylene-propylene-diene rubber with styrene and acrylonitrile, and, if necessary, other monomers such as methyl methacrylate, α-methylstyrene, ethylene bismaleimide, and maleimide.

Examples of styrene-based resins (C) also include polystyrene, which is obtained by polymerizing styrene. Examples of polystyrene include general-purpose polystyrene synthesized by manufacturing methods such as suspension polymerization and continuous polymerization, as well as high-impact polystyrene obtained by graft polymerizing styrene onto a rubber component such as butadiene rubber.

The content of structural units derived from styrene is preferably 1% by mass or more and 85% by mass or less, more preferably 5% by mass or more and 75% by mass or less, and even more preferably 5% by mass or more and 65% by mass or less, based on the total structural units of the styrene-based resin (C). When the content of structural units derived from styrene is equal to or greater than the lower limit, it is easy to impart appropriate strength to the resin composition, thereby further improving tear resistance. When the content of structural units derived from styrene is equal to or less than the upper limit, the flexibility of the resin composition is less likely to be impaired.

The melt flow rate of the styrene-based resin (C), measured in accordance with JIS K 7210:1999 at 190°C under a load of 2160 g, is preferably 0.01 g/10 min to 50 g/10 min, more preferably 0.1 g/10 min to 10 g/10 min, and even more preferably 0.2 g/10 min to 5 g/10 min. Furthermore, the melt flow rate, measured in accordance with JIS K 7210:1999 at 230°C under a load of 2160 g, is preferably 0.1 g/10 min to 100 g/10 min, more preferably 0.3 g/10 min to 50 g/10 min, and even more preferably 0.5 g/10 min to 15 g/10 min. When the melt flow rate of the styrene-based resin (C) is equal to or greater than the lower limit, the flexibility of the resin composition is less likely to be impaired. When the melt flow rate of the styrene-based resin (C) is equal to or lower than the upper limit, the resin composition is likely to be imparted with an appropriate strength, and therefore, the tearability is likely to be further improved.

The styrene-based resin (C) may be used alone or in combination of two or more types.

<Other polymers and additives>
The resin composition may contain, as necessary, other polymers than the ethylene-unsaturated ester copolymer (A) and the ethylene-α-olefin copolymer (B), various additives, a tackifying resin, an antistatic agent, an ultraviolet absorber, a filler, and the like, within the scope of not impairing the effects of the present invention.

Examples of other polymers include polyolefins such as polyethylene and polypropylene. The amount of other polymers in the resin composition is preferably 30 parts by mass or less, and more preferably 20 parts by mass or less, per 100 parts by mass of the ethylene-unsaturated ester copolymer (A), the ethylene-α-olefin copolymer (B), and the styrene-based resin (C) combined.

On the other hand, examples of additives include antioxidants, heat stabilizers, light stabilizers, pigments, dyes, lubricants, antiblocking agents, antifungal agents, antibacterial agents, flame retardants, flame retardant assistants, crosslinking agents, crosslinking assistants, foaming agents, foaming assistants, fiber reinforcements, etc.

As the tackifying resin, a hydrocarbon resin selected from the group consisting of aliphatic hydrocarbon resins, alicyclic hydrocarbon resins, and coumarone-indene resins, or a terpene resin is preferably used.
When the resin composition contains a tackifier resin, the content of the tackifier resin is preferably 4 parts by mass or less, more preferably 3 parts by mass or less, even more preferably 2 parts by mass or less, and particularly preferably 0.1 parts by mass or less, relative to 100 parts by mass of the total of the ethylene-unsaturated ester copolymer (A) and the tackifier resin.
Furthermore, the content of the tackifier resin is preferably 2 parts by mass or less, more preferably 1 part by mass or less, even more preferably 0.5 parts by mass or less, and particularly preferably 0.1 parts by mass or less, when the total of the ethylene-unsaturated ester copolymer (A), the styrene-based resin (C), and the tackifier resin is 100 parts by mass.

Examples of antistatic agents include low molecular weight antistatic agents and polymeric antistatic agents, with polymeric antistatic agents being preferred. Examples of polymeric antistatic agents include vinyl copolymers having sulfonate groups in the molecule, alkyl sulfonates, alkylbenzene sulfonates, betaines, etc. Other examples of polymeric antistatic agents include inorganic protonic acid salts of polyethers, polyamide elastomers, polyester elastomers, polyether amides, or polyether ester amides. Examples of inorganic protonic acid salts include alkali metal salts, alkaline earth metal salts, zinc salts, and ammonium salts.

Examples of UV absorbers include benzophenones, benzoates, benzotriazoles, cyanoacrylates, hindered amines, etc.

Examples of fillers include silica, clay, calcium carbonate, barium sulfate, glass beads, talc, etc.

The amounts of additives, antistatic agents, UV absorbers, and fillers are selected appropriately depending on their types.

<Method for producing resin composition and physical properties of resin composition>
The method for producing the resin composition of the present invention is not particularly limited as long as it is a method that allows the ethylene-unsaturated ester copolymer (A), the ethylene-α-olefin copolymer (B), the styrene-based resin (C), and, if necessary, other polymers and additives to be mixed. For example, all components may be dry-blended and then melt-kneaded, or some components may be kneaded first and then the remaining components may be added.

The shape of the resin composition after kneading is not particularly limited, and may be, for example, pellets, or may be processed into a long or individual sheet.

As described above, the resin composition has high flexibility derived from the ethylene-unsaturated ester copolymer (A). Specifically, the initial hardness (Shore A) of the layer containing the resin composition, measured in accordance with JIS K 7215:1996, is not particularly limited, but is preferably 75 or less, more preferably 73 or less, and even more preferably 71 or less.

The hardness (Shore A) of the layer containing the resin composition measured in accordance with JIS K 7215:1996 15 seconds after the start of measurement is not particularly limited, but is preferably 72 or less, more preferably 69 or less, and even more preferably 67 or less. When the initial hardness (Shore A) value and the value after 15 seconds of the layer containing the resin composition are both within the above ranges, the layer containing the resin composition has greater flexibility, resulting in better conformability to uneven surfaces when used as a substrate for a backgrid film.

The hardness (Shore A) of the layer containing the resin composition can be adjusted by, for example, the type and melt flow rate of the ethylene-unsaturated ester copolymer (A), ethylene-α-olefin copolymer (B), and styrene-based resin (C), as well as their composition ratios. For example, increasing the content of structural units derived from unsaturated esters in the ethylene-unsaturated ester copolymer (A) or increasing the melt flow rate tends to lower the hardness of the layer containing the resin composition. Furthermore, increasing the relative content of the ethylene-unsaturated ester copolymer (A) or increasing the melt flow rate tends to lower the hardness of the layer containing the resin composition.

The melt flow rate of the layer containing the resin composition, measured in accordance with JIS K 7210:1999 at 190°C under a load of 2160 g, is not particularly limited, but is preferably 0.1 g/10 min to 100 g/10 min, more preferably 1 g/10 min to 70 g/10 min, even more preferably 5 g/10 min to 50 g/10 min, and particularly preferably 10 g/10 min to 40 g/10 min. When the melt flow rate of the layer containing the resin composition is within the above range, not only is moldability good, but flexibility and tear resistance are also improved.

The tear strength of the layer containing the resin composition in the machine direction (MD) and transverse direction (TD) per mm of thickness is preferably 20 N/mm or less, and more preferably 15 N/mm or less. When the tear strength of the layer containing the resin composition is within the above range, it has good tearability, and when used as the base material for a backgrinding film, it is easy to cut into the shape of a semiconductor wafer, and the generation of chips and whiskers is even less likely.

The tear strength can be measured by the following procedure.
Using a cast molding machine, the resin composition is cast at a processing temperature of 200°C to prepare a 250 μm thick film. The obtained film is cut into a size of 150 mm x 50 mm, and a 75 mm cut is made in the longitudinal direction from the center of the 50 mm width. Using an autograph, the cut sample is torn from top to bottom at a chuck distance of 75 mm and a speed of 1000 mm/min, and the average strength is determined. The average strength is then divided by the measured thickness of the sample to calculate the strength per 1 mm thickness (unit: N/mm), which is taken as the tear strength.

The tear strength of the layer containing the resin composition can be adjusted by, for example, the type, melt flow rate, and content of the ethylene-α-olefin copolymer (B) and styrene-based resin (C). For example, increasing the content of ethylene-α-olefin copolymer (B) or styrene-based resin (C) or decreasing the melt flow rate tends to lower the tear strength of the layer containing the resin composition, resulting in better tearability.

2. Regarding the backgrid film substrate: The backgrid film substrate may be a substrate having at least one layer containing the above-described resin composition. Because the backgrid film substrate has a layer containing the above-described resin composition, it has excellent flexibility and tearability. The backgrid film substrate is suitable for use as a substrate for a backgrid film, but is not limited to this application.

The configuration of the backglide film substrate is not particularly limited, and it may have only one layer containing the resin composition described above, or may have two or more layers containing the resin composition described above. Furthermore, other resin layers may be laminated on the substrate as needed.

Examples of backglide film substrates include single-layer laminates consisting of only a layer containing the resin composition described above; two-layer laminates consisting of a layer containing the resin composition described above and another resin layer; and three-layer laminates consisting of a layer containing the resin composition described above, another resin layer, and another layer containing the resin composition described above. In addition to the above, the backglide film substrate may also include a layer containing an adhesive, an adhesive sheet, etc.

Here, the layer containing the above-mentioned resin composition may be a layer consisting solely of the above-mentioned resin composition, or may be a layer containing the above-mentioned resin composition together with other components to the extent that the objectives and effects of the present invention are not impaired. However, from the viewpoint of the flexibility and tearability of the backglide film substrate, it is preferable that the layer be essentially consisting of the above-mentioned resin composition.

The thickness of the layer containing the above-mentioned resin composition is not particularly limited, but from the viewpoint of improving the semiconductor wafer retention ability and heat shrinkage resistance of the backglide film substrate, it is preferable that it be moderately thick, preferably 50 μm or more and 500 μm or less, and more preferably 60 μm or more and 400 μm or less.

The initial and 15-second Shore A hardness values of the layer containing the resin composition, measured in accordance with JIS K 7215:1996, are preferably as described above. Furthermore, the tear strength per mm of thickness in the MD and TD directions of the layer containing the resin composition are preferably also as described above.

On the other hand, examples of other resin layers include layers containing linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), ethylene-α-olefin copolymer, polypropylene, ethylene-unsaturated carboxylic acid copolymer or its ionomer, ethylene-unsaturated carboxylic acid-unsaturated carboxylic acid alkyl ester terpolymer or its ionomer, ethylene-unsaturated carboxylic acid alkyl ester copolymer, ethylene-vinyl ester copolymer, ethylene-unsaturated carboxylic acid alkyl ester-carbon monoxide copolymer, unsaturated carboxylic acid graft products thereof, polyvinyl chloride, etc. The other resin layer may contain only one of these resins, or two or more.

The thickness of the other resin layer is not particularly limited, but in order to avoid impairing the flexibility and tearability of the layer containing the resin composition, it is preferably 10 μm or more and 100 μm or less, and more preferably 15 μm or more and 80 μm or less.

Here, considering that the backgrind film substrate will be used as a component of the backgrind film, the overall thickness of the backgrind film substrate is preferably 50 μm or more from the viewpoint of improving semiconductor wafer retention and heat shrinkage resistance during backgrinding, and is preferably 600 μm or less from the viewpoint of improving conformability to the irregularities on the circuit surface of the semiconductor wafer. In particular, the overall thickness of the backgrind film substrate is more preferably 60 μm or more and 480 μm or less.

The surface of the backgrind film substrate may be subjected to various treatments, such as corona treatment. It may also be subjected to electron beam irradiation.

The manufacturing method of the backgrind film substrate is not particularly limited, and it can be manufactured by known molding methods. For example, when manufacturing a backgrind film substrate consisting only of a layer containing the above-mentioned resin composition, the above-mentioned resin composition can be molded by conventionally known methods such as T-die casting, T-die nip molding, inflation molding, extrusion lamination, and calendar molding.

On the other hand, when the backgrind film substrate is a laminate of a layer containing the above-mentioned resin composition and another resin layer, the above-mentioned resin composition and the other resin may be formed by a co-extrusion lamination method or the like. Alternatively, the layer containing the above-mentioned resin composition and the other resin layer may be prepared separately and then bonded together using an adhesive or adhesive sheet. Examples of adhesive or adhesive sheet materials include various ethylene copolymers or their unsaturated carboxylic acid grafted products. When the backgrind film substrate is a laminate of a layer containing the above-mentioned resin composition and another resin layer, either the layer containing the above-mentioned resin composition or the other resin layer may be formed first, and the other layer may then be formed and laminated on top of the first layer using a T-die film molding machine, extrusion coating molding machine, or the like.

3. Regarding the backgrind film The backgrind film of the present invention only needs to comprise the above-mentioned backgrind film substrate and an adhesive layer laminated on at least one side thereof, and may also include other components as necessary. In addition, when the above-mentioned backgrind film substrate is composed of multiple layers, it is preferable that a layer containing a resin composition in the backgrind film substrate and an adhesive layer are laminated.

The adhesive that makes up the adhesive layer can be an adhesive commonly used in adhesive layers for backgrind films. Examples of adhesives include rubber-based, acrylic-based, silicone-based, and polyvinyl ether-based adhesives; radiation-curable adhesives; and heat-foamable adhesives. In particular, considering the releasability of the backgrind film from the semiconductor wafer, it is preferable for the adhesive layer to contain a radiation-curable adhesive, and it is even more preferable for it to contain an ultraviolet-curable adhesive.

UV-curable adhesives typically contain a radically polymerizable compound (which may be a monomer, oligomer, or polymer) and a photopolymerization initiator, and may also contain additives such as crosslinkers, tackifiers, fillers, antioxidants, and colorants as needed.

Examples of radically polymerizable compounds include monomers or oligomers of alkyl (meth)acrylate esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, and isononyl (meth)acrylate; monomers or oligomers of hydroxyalkyl (meth)acrylate esters such as hydroxyethyl (meth)acrylate, hydroxybutyl (meth)acrylate, and hydroxyhexyl (meth)acrylate; and the above alkyl (meth)acrylate esters and/or hydroxyalkyl (meth)acrylate esters in combination with other monomers (e.g., (meth)acrylic acid, itaconic acid, maleic anhydride, (meth)acrylic acid amide, (meth)acrylic acid N-hydroxymethylamide, and alkylaminoalkyl (meth)acrylate. copolymerizable monomers or oligomers with (meth)acrylic acid and polyhydric alcohols such as glycidyl (meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,6-hexanediol (meth)acrylate, neopentyl glycol di(meth)acrylate, and dipentaerythritol hexa(meth)acrylate, as well as oligomers thereof; and isocyanurates such as 2-propenyldi-3-butenyl cyanurate, 2-hydroxyethylbis(2-acryloxyethyl)isocyanurate, tris(2-methacryloxyethyl)isocyanurate, and tris(2-methacryloxyethyl)isocyanurate.

Examples of photopolymerization initiators include benzoin alkyl ethers such as benzoin methyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; aromatic ketones such as α-hydroxycyclohexyl phenyl ketone; aromatic ketals such as benzil dimethyl ketal; and thioxanthones such as polyvinylbenzophenone, chlorothioxanthone, dodecylthioxanthone, dimethylthioxanthone, and diethylthioxanthone.

Examples of crosslinking agents include polyisocyanate compounds, melamine resins, urea resins, polyamines, carboxyl group-containing polymers, etc.

The thickness of the adhesive layer is selected appropriately depending on the type of adhesive, and is preferably 3 to 100 μm, and more preferably 3 to 50 μm.

The adhesive layer of the backgrind film may also be protected by a separator. When the adhesive layer is protected by a separator, the surface of the adhesive layer can be kept smooth. This also makes it easier to handle and transport the backgrind film, and makes it possible to process labels on the separator. The separator is peeled off when the backgrind film is used.

The separator may be paper or a synthetic resin film such as polyethylene, polypropylene, or polyethylene terephthalate. Furthermore, the surface of the separator that comes into contact with the adhesive layer may be subjected to a release treatment such as silicone treatment or fluorine treatment, if necessary, to improve releasability from the adhesive layer. The thickness of the separator is typically 10 to 200 μm, preferably approximately 25 to 100 μm.

The method for manufacturing the backgrind film is not particularly limited. For example, the film may be manufactured by applying an adhesive to the dicing substrate described above using a known method. The adhesive can be applied using a gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, spray coater, or the like. Alternatively, the adhesive may be applied to a release sheet to form an adhesive layer, which may then be transferred to the backgrind film substrate, thereby laminating the backgrind film substrate and adhesive layer. Alternatively, the backgrind film substrate and adhesive layer may be formed simultaneously by co-extrusion, for example.

The present invention will be described below with reference to examples. The examples should not be construed as limiting the scope of the present invention. Melt flow rate (MFR) was measured in accordance with JIS K 7210:1999. Melting point was measured in accordance with JIS K 7121 (1987).

[Material preparation]
The components used were as follows:

<Ethylene-Unsaturated Ester Copolymer (A)>
EVA: ethylene-vinyl acetate copolymer (content of structural units derived from ethylene: 67% by mass, content of structural units derived from vinyl acetate: 33% by mass, MFR (190°C, 2160 g load): 30 g/10 min)

<Ethylene/α-olefin copolymer (B)>
PO1: ethylene/1-butene copolymer (manufactured by Mitsui Chemicals, Inc., Tafmer DF710 (trade name), MFR (190°C, 2160g load) 1.2g/10min, density 870kg/m ³ , melting point 55°C)

<Styrene-based resin (C)>
Styrene-based resin 1: hydrogenated styrene-based thermoplastic elastomer SEBS (content of structural units derived from styrene: 30% by mass, manufactured by Asahi Kasei Corporation, Tuftec H1041 (trade name), MFR (190°C, 2160 g load): 0.3 g/10 min, MFR (230°C, 2160 g load): 5 g/10 min)
Styrene-based resin 2: hydrogenated styrene-based thermoplastic elastomer SEBS (content of structural units derived from styrene: 18% by mass, manufactured by Asahi Kasei Corporation, Tuftec H1062 (trade name), MFR (190°C, 2160 g load): 0.7 g/10 min, MFR (230°C, 2160 g load): 4.5 g/10 min)
Styrene-based resin 3: hydrogenated styrene-based thermoplastic elastomer SEBS (content of structural units derived from styrene: 13% by mass, Kraton G1657MS (trade name), manufactured by Kraton Polymers, MFR (190°C, 2160 g load): 1.6 g/10 min, MFR (230°C, 2160 g load): 8.5 g/10 min)
Styrene-based resin 4: Hydrogenated styrene-based thermoplastic elastomer acid-modified SEBS (content of structural units derived from styrene: 30% by mass, manufactured by Asahi Kasei Corporation, Tuftec M1913 (trade name), MFR (190°C, 2160 g load): 0.3 g/10 min, MFR (230°C, 2160 g load): 5 g/10 min, acid value: 10 mg CH ₃ ONa/g)
Styrene-based resin 5: hydrogenated styrene-based thermoplastic elastomer SEBS (content of structural units derived from styrene: 62% by mass, manufactured by Asahi Kasei Corporation, Tuftec SOE1611 (trade name), MFR (190°C, 2160 g load): 4 g/10 min)
Styrene elastomer 6: hydrogenated styrene-based thermoplastic elastomer SEBS (content of structural units derived from styrene: 10% by mass, manufactured by JSR Corporation, Dynaron 1320P (trade name), MFR (190°C, 2160 g load): 0.7 g/10 min, MFR (230°C, 2160 g load): 3.5 g/10 min)

<Other resins>
PO2: ethylene/1-butene copolymer (manufactured by Mitsui Chemicals, Inc., Tafmer DF7350 (trade name), MFR (190°C, 2160g load) 25g/10min, density 870kg/m ³ , melting point 55°C)
LDPE: high-pressure low-density polyethylene (MFR (190°C, 2160g load) 1.1g/10min, density 917kg/ ^m3 )
EMAA: ethylene-methacrylic acid copolymer (content of structural units derived from ethylene: 91% by mass, content of structural units derived from methacrylic acid: 9% by mass, MFR (190°C, 2160 g load): 2.5 g/10 min, density: 930 kg/m ³ )

[Examples 1 to 7 and Comparative Examples 1 to 4]
The ethylene-unsaturated ester copolymer (A) and the ethylene-α-olefin copolymer (B) or the styrene-based resin (C) were dry-blended in a charge amount of 10 kg in the ratio (mass ratio) shown in Table 1. Next, the dry-blended mixture was charged into the resin inlet of a 30 mmφ twin-screw extruder (L/D = 32) and melt-kneaded at a processing temperature of 160°C to obtain a resin composition for a backgrind film substrate.

The melt flow rate (MFR) of the resulting resin composition for backgrind film substrate was measured at 190°C under a load of 2,160 g in accordance with JIS K 7210:1999. The measurement results are shown in Table 1.

[Flexibility evaluation]
The obtained resin composition for backgrind film substrate was used to prepare a 150 mm x 150 mm x 3 mm thick backgrind film substrate using a heat press set at 160 ° C. Test specimens were punched out of the prepared backgrind film substrate into strips measuring 20 mm wide x 100 mm long and stored in an atmosphere of 23 ° C and 50% relative humidity for 2 weeks. Two backgrind film substrates were then stacked and the hardness (Shore A) was measured using an Asker automatic rubber hardness tester P1-D. The measured values were read as the initial value and the value after 15 seconds. The measurement conditions were in accordance with JIS K 7215:1996. The measurement results are shown in Table 1.

The initial value of hardness (Shore A) was evaluated for flexibility according to the following criteria.
A (Good): 71 or less B (Fairly good): Over 71 and under 75 C (Poor): Over 75

The hardness (Shore A) value after 15 seconds was used to evaluate flexibility according to the following criteria.
A (good): 67 or less B (fairly good): over 67 and under 72 C (poor): over 72

[Evaluation of tearability]
The obtained resin composition for backgrind film substrate was cast molded using a 40 mmφ cast molding machine at a processing temperature of 200 ° C, a rotation speed of 100 rpm, and a processing speed of 3 m / min to produce a 250 μm thick backgrind film substrate. A 150 mm x 50 mm sample was cut from the obtained backgrind film substrate, and a 75 mm slit was made in the longitudinal direction from the center of the 50 mm width. Using an autograph, the slit sample was torn vertically at a chuck distance of 75 mm and a speed of 1000 mm / min, and the average strength was determined. The average strength was divided by the measured thickness of the sample to calculate the strength N / mm per 1 mm thickness, which was used as the tear strength. The tear strength was measured in both the MD (machine direction) and TD (transverse direction) directions of the backgrind film substrate. The measurement results are shown in Table 1.

The tear strength was evaluated according to the following criteria, which were the same for both the MD and TD directions.
A (good): 15N/mm or less B (fairly good): over 15N/mm and 20N/mm or less C (poor): over 20N/mm

As is clear from Table 1, the backgrind film substrates made using the resin compositions for backgrind film substrates of Examples 1 to 7 exhibited excellent tearability while maintaining the flexibility of EVA. In contrast, the backgrind film substrates made using the resin compositions for backgrind film substrates of Comparative Examples 1 to 4 either failed to maintain the flexibility of EVA, or, even if they maintained the flexibility of EVA, exhibited poor tearability.

From the above, it has been confirmed that the resin composition for backgrind film substrates according to this embodiment makes it possible to realize backgrind film substrates with excellent tear resistance while maintaining the flexibility of EVA.

This application claims priority from Japanese Patent Application No. 2022-39221, filed March 14, 2022. The entire contents of that application are incorporated herein by reference.

The resin composition for backgrind film substrates of the present invention allows for the production of backgrind film substrates that are both highly flexible and tear-resistant. Therefore, they are extremely useful in the field of semiconductor device manufacturing.

Claims (11)

an ethylene-unsaturated ester copolymer (A);
at least one resin selected from the group consisting of an ethylene/α-olefin copolymer (B) and a styrene-based resin (C) having a melt flow rate of 0.1 g/10 min or more and less than 25 g/10 min, as measured at 190°C under a load of 2160 g in accordance with JIS K 7210:1999;
Including,
the ethylene/α-olefin copolymer (B) has a melting point of less than 100°C,
the content of the ethylene-unsaturated ester copolymer (A) is more than 60 parts by mass and less than 100 parts by mass when the total amount of the ethylene-unsaturated ester copolymer (A), the ethylene-α-olefin copolymer (B), and the styrene-based resin (C) is 100 parts by mass;
Resin composition for backgrind film substrate. The ethylene-unsaturated ester copolymer (A) has a content of structural units derived from an unsaturated ester of 15% by mass or more and 46% by mass or less.
The resin composition for a backgrind film substrate according to claim 1 . the ethylene-unsaturated ester copolymer (A) has a melt flow rate, measured in accordance with JIS K 7210:1999 at 190°C under a load of 2160 g, of 0.1 g/10 min or more and 100 g/10 min or less;
The resin composition for a backgrind film substrate according to claim 1 . the styrene-based resin (C) has a melt flow rate, measured in accordance with JIS K 7210:1999 at 190°C under a load of 2160 g, of 0.01 g/10 min or more and 50 g/10 min or less;
The resin composition for a backgrind film substrate according to claim 1 . The styrene-based resin (C) is a styrene-based elastomer.
The resin composition for a backgrind film substrate according to claim 1 . the total amount of the ethylene-unsaturated ester copolymer (A), the ethylene-α-olefin copolymer (B), and the styrene-based resin (C) is 70% by mass or more and 100% by mass or less, when the entire resin composition for a backgrind film is taken as 100% by mass;
The resin composition for a backgrind film substrate according to claim 1 . The ethylene-unsaturated ester copolymer (A) is an ethylene-vinyl acetate copolymer.
The resin composition for a backgrind film substrate according to claim 1 . The backgrind film has at least one layer containing the resin composition for a backgrind film substrate according to any one of claims 1 to 7 .
Backgrind film substrate. The layer containing the resin composition for a backgrind film substrate has an initial hardness (Shore A) of 75 or less as measured in accordance with JIS K 7215:1996.
The backgrind film substrate of claim 8 . the layer containing the resin composition for a backgrind film substrate has a hardness (Shore A) of 72 or less 15 seconds after the start of measurement, as measured in accordance with JIS K 7215:1996;
The backgrind film substrate of claim 8 . The backgrind film substrate according to claim 8 ;
an adhesive layer laminated on at least one surface of the backgrind film substrate;
having
Backgrind film.