Resin compositions and laminated films

Abstract

To provide a resin composition that yields a laminated film that stretches uniformly in all directions while its yield point disappears, possesses moderate tensile strength, and exhibits excellent recovery delay properties suggesting stress relaxation (i.e., slowly returns to its original dimensions after stress release), a laminated film, and a laminated film that is suitably used as a dicing film. [Solution] A resin composition comprising 20 to 50 parts by mass of a 4-methyl-1-pentene-α-olefin copolymer (A) that satisfies specific requirements, 20 to 60 parts by mass of a propylene-based elastomer (B) that satisfies specific requirements (Ba) to (Bd), and 5 to 50 parts by mass of homopolypropylene (C) (where the total of copolymer (A), propylene-based elastomer (B), and homopolypropylene (C) is 100 parts by mass).

Description

[Technical Field]

[0001] The present invention relates to a resin composition and a laminated film, and an example of such a laminated film is a dicing film used in semiconductor manufacturing processes. [Background technology]

[0002] The semiconductor manufacturing process involves sequential steps such as a backgrinding process, where the semiconductor wafer is polished to adjust its thickness; a dicing process, where the dicing film is set on a ring frame, attached and fixed, and then cut into chip shapes; an expand process, where the dicing film is expanded to separate the chips; and a pickup process, where each chip is acquired, before being mounted onto a predetermined base. This film is frequently used not only in the dicing process but also in the subsequent expand process.

[0003] In recent years, with the miniaturization and thinning of semiconductor devices, the films used in these devices require not only flexibility during expansion but also the ability to prevent chip damage and loss. Conventionally, PVC (polyvinyl chloride resin) substrates have been used, and plasticizers have been added to provide flexibility. However, there has been a problem with these plasticizers bleeding out and contaminating the chips and substrates. Furthermore, there is a growing trend in the industry to regulate the use of plasticizers or to reduce the use of halogen-derived components.

[0004] Patent Document 1 discloses a polyolefin film having uniform expandability and resilience. The proposed polyolefin film comprises a surface layer and a base layer, the base layer being a random copolymer of propylene and ethylene and / or α-olefins having 4 to 8 carbon atoms. The film disclosed in Patent Document 1 has a high resilience, so it is expected that loosening will not occur after expansion, and the heating process to remove loosening can be omitted.

[0005] Patent Document 2 discloses a dicing substrate film that maintains expandability and stretches uniformly even at low temperatures. The proposed dicing substrate film includes a structure in which a surface layer / intermediate layer / back layer are laminated in that order, the surface layer and back layer being made of a resin composition containing a polyethylene resin, and the intermediate layer being made of a resin composition containing at least one resin selected from the group consisting of polyethylene resins, vinyl aromatic hydrocarbon resins, and amorphous polyolefins.

[0006] Patent Document 3 discloses a substrate film for semiconductor manufacturing processes that provides antistatic properties and possesses flexibility and heat resistance. The proposed substrate film for semiconductor manufacturing processes has at least one resin layer composed of a resin composition containing homopolypropylene, a polymer-type antistatic agent, and a thermoplastic elastomer. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2018-065327 [Patent Document 2] Japanese Patent Publication No. 2018-125521 [Patent Document 3] Japanese Patent Publication No. 2020-084143 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] However, the film described in Patent Document 1 has a relatively low tensile modulus, making it unsuitable for application in the expansion process, which involves expanding the dicing film to separate the chips. The film described in Patent Document 2 uses only polyethylene-based resins with low melting points, and while it can be assumed to have expandability at low temperatures, its heat resistance is poor, and further improvements are considered necessary. Although the film described in Patent Document 3 has antistatic properties and heat resistance, it has the problem of being prone to blocking between films when obtaining a film with low surface roughness and high transparency.

[0009] In view of the above-mentioned problems, the present invention aims to provide a resin composition that yields a laminated film that stretches uniformly in all directions while eliminating the yield point, has appropriate tensile strength, and exhibits excellent recovery delay properties suggesting stress relaxation (i.e., slowly returns to its original dimensions after stress release), a laminated film, and a laminated film that is suitably used as a dicing film. [Means for solving the problem]

[0010] In other words, the present invention and the means for solving the above problems relate, for example, to the following matters [1] to [6]. [1] 20 to 50 parts by mass of a 4-methyl-1-pentene·α-olefin copolymer (A) that satisfies the following requirements (Aa) to (Ad), A propylene-based elastomer (B) that satisfies the following requirements (Ba) to (Bd) is comprising 20 to 60 parts by mass, Homopolypropylene (C) 5 to 50 parts by mass, A resin composition containing (wherein the total of copolymer (A), propylene elastomer (B), and homopolypropylene (C) is 100 parts by mass). Requirement (Aa): Consists of 60-90 mol% of constituent unit (i) derived from 4-methyl-1-pentene and 10-40 mol% of constituent unit (ii) derived from α-olefins having 2-4 carbon atoms (provided that the sum of constituent unit (i) and constituent unit (ii) is 100 mol%). Requirement (Ab): The intrinsic viscosity [η] measured in decalin at 135°C is in the range of 0.5 to 5.0 dl / g. Requirement (Ac): The melting point (Tm) measured by differential scanning calorimeter (DSC) is not observed or is in the range of less than 160°C. Requirements (Ad): Density of 820-860 kg / m³ 3 It is within the range. Requirement (B-a): The melting point (Tm) measured by differential scanning calorimetry (DSC) is in the range of 130 to 170 °C. Requirement (B-b): The glass transition temperature (Tg) measured by differential scanning calorimetry (DSC) is in the range of -25 to -35 °C. Requirement (B-c): The Shore A hardness measured by ASTM D2240 is in the range of 65 to 90. Requirement (B-d): The density is in the range of 860 to 875 kg / m 3 .

[0011] [2] A laminated film laminated in the order of surface layer (X) / intermediate layer (Y) / back layer (Z), The surface layer (X) and the back layer (Z) contain homopolypropylene (C), The intermediate layer (Y) is a laminated film containing the resin composition described in [1].

[0012] [3] The laminated film described in [2], wherein the tensile modulus measured in accordance with JIS K7127 at 23 °C and a test speed of 500 mm / min is 200 to 1000 MPa.

[0013] [4] The laminated film described in [2] or [3], wherein the difference in tensile stress between the MD direction (Machine Direction) and the TD direction (Traverse Direction) at 23 °C, a test speed of 500 mm / min, and a strain of 20% measured in accordance with JIS K7127 is 2.0 MPa or less.

[0014] [5] The laminated film described in any one of [2] to [4], wherein the stress relaxation rate represented by the following formula (1) is 30% or more when the load immediately after 20% elongation is G and the load after holding for 3 minutes is H, measured in accordance with JIS K7127 at 23 °C and a test speed of 500 mm / min. {(G - H) / G} × 100 ···(1)

[0015] [6] A laminated film according to any of [2] to [5], wherein the yield point measured in accordance with JIS K7127 at 23°C and a test speed of 500 mm / min is not observed in either the MD direction or the TD direction.

[0016] [7] A laminated film as described in any of [2] to [6] used in semiconductor manufacturing processes. [Effects of the Invention]

[0017] The present invention provides a resin composition and a laminated film that exhibits uniform elongation in all directions while eliminating the yield point, possesses moderate tensile strength, and further exhibits excellent recovery delay, suggesting a stress relaxation rate (i.e., slowly returns to its original dimensions after the release of tensile stress). The laminated film can be suitably used as a dicing film in semiconductor manufacturing processes. [Modes for carrying out the invention]

[0018] The following describes specific embodiments of the present invention in detail, but the present invention is not limited in any way to the following embodiments, and can be implemented with appropriate modifications within the scope of the present invention.

[0019] In this specification, a range of numbers represented using "~" means a range that includes the numbers written before and after "~" as the lower and upper limits, respectively. In this specification, when referring to the amount of each component in a composition, if there are multiple substances corresponding to each component in the composition, unless otherwise specified, it refers to the total amount of all substances present in the composition.

[0020] <4-methyl-1-pentene-α-olefin copolymer (A)> One of the components contained in the resin composition of the present invention, 4-methyl-1-pentene·α-olefin copolymer (A) (hereinafter sometimes abbreviated as "polymer (A)"), is a copolymer of 4-methyl-1-pentene and α-olefin, and satisfies the following requirements (Aa) to (Ad). The copolymer (A) may be a single type or a combination of two or more types.

[0021] 《Requirement (Aa)》 Copolymer (A) consists of 60-90 mol% of structural unit (i) derived from 4-methyl-1-pentene and 10-40 mol% of structural unit (ii) derived from α-olefins having 2-4 carbon atoms (provided that the sum of structural unit (i) and structural unit (ii) is 100 mol%).

[0022] The content of each constituent unit in copolymer (A) is determined by carbon-13 nuclear magnetic resonance (hereinafter referred to as " 13 Also known as "C-NMR," the results were calculated using a measurement method. The content of each constituent unit was determined using the apparatus and conditions described in the examples below. 13 This can be calculated by measuring the 1C-NMR spectrum.

[0023] The content of constituent unit (i) is 60 to 90 mol%, preferably 65 to 89 mol%, more preferably 68 to 88 mol%, and even more preferably 70 to 87 mol%. When the content of constituent unit (i) is above the lower limit, the copolymer (A) exhibits excellent dispersibility with propylene-based elastomer (B) and homopolypropylene (C). Furthermore, when the content of constituent unit (i) is above the lower limit, the transparency of the resulting laminated film can be maintained without deterioration. When the content of constituent unit (i) is below the upper limit, the resulting laminated film exhibits excellent recovery delay properties, suggesting stress relaxation (i.e., it slowly returns to its original dimensions after stress release).

[0024] The content of constituent unit (ii) is 10 to 40 mol%, preferably 11 to 35 mol%, more preferably 12 to 32 mol%, and even more preferably 13 to 30 mol%. When the content of constituent unit (ii) is equal to or greater than the lower limit, the resulting laminated film exhibits excellent recovery delay properties, suggesting stress relaxation (i.e., it slowly returns to its original dimensions after stress release). When the content of constituent unit (ii) is below the upper limit, the copolymer (A) exhibits excellent dispersibility with propylene-based elastomer (B) and homopolypropylene (C). Furthermore, when the content of constituent unit (ii) is below the upper limit, the transparency of the resulting laminated film can be maintained without deterioration.

[0025] Examples of α-olefins having 2 to 4 carbon atoms that derive the constituent unit (ii) include ethylene, propylene, and 1-butene. The α-olefin may be one type or two or more types. The α-olefin is preferably propylene. When the α-olefin is propylene, the copolymer (A) exhibits excellent dispersibility in propylene-based elastomer (B) and homopolypropylene (C). The monomers constituting the copolymer (A) may be monomers derived from fossil fuels, monomers derived from biomass, or mixtures thereof.

[0026] Copolymer (A) can improve the conformability of the film in the dicing process, in which the dicing film as a laminated film is set on a ring frame and fixed in place. For improved conformability in the dicing process, it is preferable that copolymer (A) not only imparts flexibility to the laminated film but also has high stress relaxation properties.

[0027] Stress relaxation properties can be evaluated, for example, by the loss tangent tanδ, which is expressed as the ratio (G'' / G') of the storage modulus G' to the loss modulus G'' measured by dynamic viscoelasticity. The storage modulus G' is the elastic component that stores and maintains the energy of stress when it is applied. The loss modulus G'' is the viscous component that converts the energy of stress into heat and dissipates it (diffuses to the outside) when it is applied. Therefore, the higher the loss tangent tanδ of a material under a specific temperature environment, the easier it is to absorb shock and the greater the stress relaxation performance it exhibits.

[0028] The tanδ peak value of copolymer (A), determined by dynamic viscoelasticity measurement with a temperature range of -40 to 150°C, torsion mode (torsional deformation), frequency of 1.0 Hz, heating rate of 4°C / min, and strain of 0.5%, is preferably in the range of 0.5 to 5.0, more preferably 0.6 to 4.5, even more preferably 0.7 to 4.0, and particularly preferably 1.0 to 3.5. The maximum value of the loss tangent tanδ measured in the dynamic viscoelasticity measurement is defined as the tanδ peak value.

[0029] The tanδ peak temperature of copolymer (A), determined by dynamic viscoelasticity measurement with a temperature range of -40 to 150°C, torsion mode (torsional deformation), frequency of 1.0 Hz, heating rate of 4°C / min, and strain of 0.5%, is preferably in the range of -20 to 60°C, more preferably -10 to 55°C, and even more preferably 0 to 50°C. The temperature at which the loss tangent tanδ measured in the dynamic viscoelasticity measurement reaches the tanδ peak value is defined as the tanδ peak temperature.

[0030] When the tanδ peak value and tanδ peak temperature of copolymer (A) are within the aforementioned range, the laminated film exhibits excellent conformability and delayed recovery, which is the behavior of slowly returning to its original dimensions when stress is released after stretching. The specific methods for measuring the tanδ peak value and tanδ peak temperature in copolymer (A) are described in the examples below. The tanδ peak value and tanδ peak temperature can be adjusted by changing the composition of constituent units (i) and (ii) in copolymer (A).

[0031] 《Requirements (Ab)》 The intrinsic viscosity [η] of copolymer (A), measured in decalin solvent at 135°C, is in the range of 0.5 to 5.0 dl / g, preferably 0.6 to 4.0 dl / g, and more preferably 0.8 to 3.0 dl / g. When the intrinsic viscosity [η] of copolymer (A) is within this range, the low content of low molecular weight components reduces stickiness and facilitates film formation. The intrinsic viscosity [η] can be calculated by measuring the specific viscosity under the conditions described in the examples below.

[0032] 《Requirements (Ac)》 The melting point (Tm) of copolymer (A), as measured by differential scanning calorimeter (DSC), is either not observed or is in the range of less than 160°C. If copolymer (A) has a melting point, the melting point is preferably 150°C or less, more preferably 145°C or less, and even more preferably 140°C or less.

[0033] The melting point can be adjusted by changing the stereoregularity of copolymer (A), the type of α-olefin that leads to the constituent unit (ii), and the content of the constituent unit (ii). Furthermore, the melting point can be adjusted to a desired composition using a polymerization catalyst, as described later. The melting point (Tm) is measured using a differential scanning calorimeter (DSC), and the details of the measurement method are described in the examples below.

[0034] 《Requirements(Ad》) The density of copolymer (A) is 820-860 kg / m³. 3 Preferably 825-855 kg / m 3 , more preferably 830-850 kg / m 3 It is within the range. When the density of copolymer (A) is within the range described above, flexibility can be imparted to the laminated film. Density can be measured using a density gradient tube in accordance with JIS K7112.

[0035] In copolymer (A), the molecular weight distribution (Mw / Mn), which is the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) measured by gel permeation chromatography (GPC), is preferably in the range of 1.0 to 4.0, more preferably 1.2 to 3.5, and even more preferably 1.5 to 3.0. When the molecular weight distribution (Mw / Mn) of copolymer (A) is within the above range, the influence of low molecular weight and low stereoregularity polymers is minimized, resulting in good rigidity of the laminated film.

[0036] The weight-average molecular weight (Mw) of copolymer (A), measured by gel permeation chromatography (GPC) and calculated on a polystyrene basis, is preferably in the range of 500 to 10,000,000, more preferably 1,000 to 5,000,000, and even more preferably 5,000 to 2,500,000. When the weight-average molecular weight (Mw) of copolymer (A) is within this range, the rigidity of the laminated film is good. Details of the measurement methods for Mw, Mn, and Mw / Mn are described in the examples below.

[0037] From the viewpoint of facilitating the formation of laminated films and further facilitating the adjustment of film thickness, the melt flow rate (MFR) of copolymer (A) is preferably in the range of 0.5 to 40 g / 10 min, more preferably 1.0 to 30 g / 10 min, and even more preferably 2.0 to 20 g / 10 min. The MFR can be measured in accordance with ASTM D1238 under conditions of a temperature of 230°C and a load of 2.16 kg.

[0038] <Method for producing copolymer (A)> Copolymer (A) can be produced, for example, by polymerizing 4-methyl-1-pentene and the α-olefin having 2 to 4 carbon atoms using a suitable polymerization catalyst such as a magnesium-supported titanium catalyst and a metallocene catalyst. As the polymerization catalyst, conventionally known catalysts, such as magnesium-supported titanium catalysts, metallocene catalysts described in International Publication No. 01 / 53369, International Publication No. 01 / 27124, Japanese Patent Publication No. 3-193796, Japanese Patent Publication No. 2-41303, International Publication No. 2011 / 055803, or International Publication No. 2014 / 050817, are preferably used. Polymerization can be carried out by appropriately selecting from liquid-phase polymerization methods, including dissolution polymerization and suspension polymerization, as well as gas-phase polymerization methods.

[0039] In liquid-phase polymerization, an inert hydrocarbon solvent can be used as the solvent constituting the liquid phase. Examples of inert hydrocarbons include aliphatic hydrocarbons such as propane, butane, pentane, hexane, heptane, octane, decane, dodecane, and kerosene; alicyclic hydrocarbons such as cyclopentane, cyclohexane, methylcyclopentane, and methylcyclohexane; aromatic hydrocarbons such as benzene, toluene, and xylene; halogenated hydrocarbons such as ethylene chloride, chlorobenzene, dichloromethane, trichloromethane, and tetrachloromethane; and mixtures thereof.

[0040] In liquid-phase polymerization, bulk polymerization can also be carried out using the monomer corresponding to the constituent unit (i) derived from 4-methyl-1-pentene (i.e., 4-methyl-1-pentene) or the monomer corresponding to the constituent unit (ii) derived from α-olefins having 2 to 4 carbon atoms (i.e., α-olefins having 2 to 4 carbon atoms) itself as the solvent.

[0041] By performing stepwise copolymerization of 4-methyl-1-pentene with α-olefins having 2 to 4 carbon atoms, the compositional distribution of the constituent units (i) derived from 4-methyl-1-pentene and (ii) derived from the α-olefins having 2 to 4 carbon atoms that constitute copolymer (A) can also be adjusted.

[0042] The polymerization temperature for producing copolymer (A) is preferably -50 to 200°C, more preferably 0 to 100°C, and even more preferably 20 to 100°C. The polymerization pressure for producing copolymer (A) is preferably atmospheric pressure to 10 MPa gauge pressure, more preferably atmospheric pressure to 5 MPa gauge pressure.

[0043] During the production of copolymer (A), hydrogen may be added to control the molecular weight and polymerization activity of the resulting polymer. The appropriate amount of hydrogen to add is approximately 0.001 to 100 NL per 1 kg of the total amount of 4-methyl-1-pentene and α-olefin with 2 to 4 carbon atoms.

[0044] <Propylene-based elastomer (B)> The propylene-based elastomer (B), one of the components included in the resin composition of the present invention, is a copolymer consisting of structural units derived from propylene and structural units derived from α-olefins having 2 to 20 carbon atoms (excluding propylene), and contains 50 mol% or more of structural units derived from propylene (where the total of structural units derived from propylene and structural units derived from α-olefins having 2 to 20 carbon atoms (excluding propylene) is 100 mol%). Propylene elastomer (B) may be of one type or two or more types.

[0045] Examples of α-olefins with 2 to 20 carbon atoms (excluding propylene) that constitute the propylene-based elastomer (B) include ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-octadecene, and 1-eicosane. The propylene-based elastomer (B) is a copolymer consisting of structural units derived from propylene and structural units derived from α-olefins having 2 to 20 carbon atoms (excluding propylene), but it is even more preferable that it is a copolymer consisting of structural units derived from propylene, structural units derived from ethylene, and structural units derived from α-olefins having 4 to 10 carbon atoms.

[0046] Furthermore, the content of structural units derived from propylene is preferably 50 mol% to 99 mol%, and more preferably 60 mol% to 99 mol%, when the total of structural units derived from propylene and structural units derived from α-olefins having 2 to 20 carbon atoms (excluding propylene) is taken as 100 mol%.

[0047] The propylene-based elastomer (B) satisfies the following requirements (Ba) to (Bd).

[0048] Requirements (Ba) The melting point (Tm) of the propylene-based elastomer (B), as measured by differential scanning calorimeter (DSC), is in the range of 130 to 170°C, preferably 135 to 165°C. If the melting point (Tm) of the propylene-based elastomer (B) is lower than the aforementioned range, the resulting laminated film will have poor heat resistance, which is undesirable. Conversely, if the melting point (Tm) is within the aforementioned range, it is advantageous because it facilitates the molding of the laminated film. The melting point (Tm) is measured using a differential scanning calorimeter (DSC), and the details of the measurement method are described in the examples below.

[0049] 《Requirements (Bb)》 The glass transition temperature (Tg) of the propylene-based elastomer (B), as measured by differential scanning calorimeter (DSC), is in the range of -25 to -35°C, preferably -26 to -33°C. If the glass transition temperature (Tg) of the propylene-based elastomer (B) is within the aforementioned range, the flexibility of the laminated film is maintained even at low temperatures. Therefore, because it exhibits excellent expandability at low temperatures in semiconductor manufacturing processes, a laminated film that stretches uniformly in all directions can be obtained.

[0050] 《Requirements (Bc)》 The Shore A hardness of the propylene-based elastomer (B), as measured by ASTM D2240, is in the range of 65 to 90, preferably 68 to 88, and more preferably 70 to 86. If the Shore A hardness of the propylene-based elastomer (B) is within the aforementioned range, the resulting laminated film will be flexible. This is advantageous in semiconductor manufacturing processes because it facilitates the attachment and fixing of the dicing film when it is set on the ring frame.

[0051] Shore A hardness can be measured using the following method. After the 2.0 mm thick sheets obtained under the sheet preparation conditions described below were left to stand at 23°C for 72 hours, the scale was read using a rubber hardness tester (Type A durometer) in accordance with ASTM D2240, with three sheets stacked on top of each other, at the moment of contact with the indenter. Sheet production conditions: Set the heating plate at 200 °C, preheat for 7 minutes, apply pressure at a gauge pressure of 10 MPa for 2 minutes, then transfer to the cooling plate (set at 20 °C), and compress at a gauge pressure of 10 MPa for 3 minutes for cooling.

[0052] 《Requirement (B-d)》 The density of the propylene-based elastomer (B) is in the range of 860 - 875 kg / m 3 and preferably in the range of 860 - 870 kg / m 3 . When the density is within the above range, the propylene-based elastomer (B) is preferred because it has excellent dispersibility with the copolymer (A) and the homopolypropylene (C). Also, the resulting laminated film has flexibility. In the semiconductor manufacturing process, it is advantageous because it facilitates the sticking and fixing when the dicing film is set on the ring frame. Note that the density can be measured using a density gradient tube in accordance with JIS K7112.

[0053] Also, from the viewpoint of facilitating the film formation of the laminated film and further facilitating the adjustment of the film thickness, the melt flow rate (MFR) of the propylene-based elastomer (B) is preferably in the range of 0.5 - 30 g / 10 min, more preferably in the range of 1.0 - 20 g / 10 min, and even more preferably in the range of 2.0 - 15 g / 10 min. The MFR can be measured in accordance with ASTM D1238 under the conditions of a temperature of 230 °C and a load of 2.16 kg.

[0054] The propylene-based elastomer (B) is not particularly limited as long as it satisfies the above resin physical properties. For example, commercially available products may be used. Examples of commercially available products include, but are not limited to, Toughmer PN (registered trademark) manufactured by Mitsui Chemicals, Inc.

[0055] <Homopolypropylene (C)> The homopolypropylene (C), which is one of the components contained in the resin composition of the present invention, is a homopolymer mainly composed of structural units derived from propylene. For homopolypropylene (C), melt flowlets (MFRs) can be selected depending on the target physical properties of the laminated film. Homopolypropylene (C) may be of one type or two or more types.

[0056] Furthermore, from the viewpoint of facilitating the formation of laminated films and also facilitating the adjustment of film thickness, the MFR of homopolypropylene (C) is preferably in the range of 0.5 to 30 g / 10 min, more preferably 1.0 to 20 g / 10 min, and even more preferably 2.0 to 10 g / 10 min. The MFR can be measured in accordance with ASTM D1238 under conditions of a temperature of 230°C and a load of 2.16 kg.

[0057] The melting point (Tm) of homopolypropylene (C) is preferably 155 to 170°C, more preferably 158 to 168°C, and even more preferably 160 to 165°C. Having a melting point within this range is advantageous because it facilitates the formation of laminated films and allows for the creation of laminated films with suitable heat resistance.

[0058] There are no particular restrictions on the homopolypropylene (C) as long as it satisfies the aforementioned resin properties, but commercially available products may be used, for example. Examples of commercially available products include Novatec PP (registered trademark) manufactured by Nippon Polypropylene Co., Ltd., Prime Polypropylene (registered trademark) manufactured by Prime Polymer Co., Ltd., and Sumitomo Noblen (registered trademark) manufactured by Sumitomo Chemical Co., Ltd., but the product is not limited to these.

[0059] [Resin composition] The resin composition of the present invention comprises 20 to 50 parts by mass of a 4-methyl-1-pentene·α-olefin copolymer (A) satisfying the above requirements, 20 to 60 parts by mass of a propylene-based elastomer (B) satisfying the above requirements, and 5 to 50 parts by mass of homopolypropylene (C) (provided that the total of copolymer (A), propylene-based elastomer (B), and homopolypropylene (C) is 100 parts by mass). Because the resin composition has the above configuration, the resulting laminated film stretches uniformly in all directions while its yield point disappears, possesses moderate tensile strength, and exhibits excellent recovery delay, suggesting stress relaxation properties (i.e., it slowly returns to its original dimensions after stress release).

[0060] The amount of copolymer (A), one of the components contained in the resin composition of the present invention, is preferably 22 to 48 parts by mass, more preferably 25 to 45 parts by mass, based on 100 parts by mass of the total of copolymer (A), propylene elastomer (B), and homopolypropylene (C). When the amount of copolymer (A) is within the above range, the resulting laminated film is given stress-relaxing properties and exhibits delayed recovery, which is the behavior of slowly returning to its original dimensions after being stretched to release stress.

[0061] Furthermore, if no melting point (Tm) is observed for copolymer (A) using differential scanning calorimeter (DSC), it suggests that the copolymer (A) is amorphous. When copolymer (A) is amorphous, the resulting laminated film stretches uniformly in all directions, but no yield point is observed.

[0062] When the amount of copolymer (A) is within the above range, the resulting laminated film has appropriate flexibility, which improves its conformability when setting and fixing the dicing film onto the ring frame during the dicing process in semiconductor manufacturing.

[0063] The amount of propylene elastomer (B), one of the components contained in the resin composition of the present invention, is preferably 22 to 58 parts by mass, more preferably 25 to 55 parts by mass, based on 100 parts by mass of the total of copolymer (A), propylene elastomer (B), and homopolypropylene (C). When the amount of propylene-based elastomer (B) is within the above range, the resulting laminated film exhibits appropriate flexibility, making it easier to handle as a dicing film in semiconductor manufacturing processes, which is advantageous.

[0064] In a mixture of propylene-based elastomer (B), copolymer (A), and homopolypropylene (C), it is thought that the crystalline parts are not dispersed as island phases in a sea-island structure, but rather that island phases, which are helical crystalline parts of about 10-50 nm, are interconnected, forming a network structure that covers the entire amorphous region. This network structure is said to give the mixture of propylene-based elastomer (B), copolymer (A), and homopolypropylene (C) heat resistance and flexibility.

[0065] Furthermore, if the copolymer (A) contained in the resin composition of the present invention has crystalline parts, or if the homopolypropylene (C) has high crystallinity, when stretched in one direction, the molecular chains orient in that direction of tension, and a yield point appears when transitioning from elastic deformation to plastic deformation. When this yield point appears, it becomes difficult to stretch uniformly in all directions.

[0066] In the case of propylene-based elastomer (B), the orientation of molecular chains in the tensile direction can be suppressed. Therefore, a laminated film containing a resin composition that includes propylene-based elastomer (B) along with copolymer (A) and homopolypropylene (C) is considered to have a moderate tensile strength, with uniform elongation in all directions and the yield point disappearing.

[0067] Generally, increasing the crystallinity of a resin improves its heat resistance, but tends to reduce its flexibility and make it harder. In a mixture of propylene-based elastomer (B), copolymer (A), and homopolypropylene (C), amorphous regions are incorporated into the crystalline regions at the nanometer level, forming a structure in which these amorphous regions are connected to surrounding amorphous regions. This structure is thought to improve heat resistance while maintaining flexibility.

[0068] The homopolypropylene (C) contained in the resin composition of the present invention is a homopolymer of propylene. The amount of homopolypropylene (C) is preferably 7 to 48 parts by mass, more preferably 8 to 45 parts by mass. Homopolypropylene (C) generally has a high degree of crystallinity among propylene-based resins, resulting in high rigidity and excellent heat resistance. By including homopolypropylene (C) in the resin composition of the present invention, the tensile strength of the resulting laminated film can be increased.

[0069] The resin composition of the present invention is obtained by mixing a 4-methyl-1-pentene·α-olefin copolymer (A), a propylene-based elastomer (B), and homopolypropylene (C) in specific proportions as described above. However, it can also be prepared by various known methods, such as dry blending the above components using a Henschel mixer, tumbler blender, V-blender, etc., melt kneading after dry blending using a single-screw extruder, twin-screw extruder, Banbury mixer, etc., and stirring and mixing in the presence of a solvent.

[0070] The resin composition of the present invention may contain an antioxidant as needed, to the extent that it does not impair the effects of the present invention. Known antioxidants can be used. Specifically, hindered phenol compounds, sulfur-based antioxidants, lactone-based antioxidants, organic phosphite compounds, organic phosphonite compounds, or combinations thereof can be used. Examples include phenolic compounds (2,6-di-t-butyl-4-methylphenol, etc.), polycyclic phenolic compounds (2,2'-methylenebis(4-methyl-6-t-butylphenol, etc.)), phosphorus-based compounds (tetrakis(2,4-di-t-butylphenyl)-4,4-biphenylenediphosphonate, etc.), and amine-based compounds (N,N-diisopropyl-p-phenylenediamine, etc.). One or more of these antioxidants may be used.

[0071] The resin composition of the present invention may optionally contain an antistatic agent, to the extent that it does not impair the effects of the present invention. Examples of antistatic agents include surfactants, fatty acid esters, and polymeric antistatic agents, which will be described later. Examples of fatty acid esters include esters of stearic acid and oleic acid, and examples of polymeric antistatic agents include polyether ester amides. One of these antistatic agents may be used, or two or more may be used.

[0072] Examples of surfactants include nonionic, anionic, cationic, or amphoteric surfactants. Examples of nonionic surfactants include polyethylene glycol-type nonionic surfactants such as higher alcohol ethylene oxide adducts, fatty acid ethylene oxide adducts, higher alkylamine ethylene oxide adducts, and polypropylene glycol ethylene oxide adducts; polyhydric alcohol-type nonionic surfactants such as fatty acid esters of polyethylene oxide and glycerin, fatty acid esters of pentaerythritol, fatty acid esters of sorbitol or sorbitan, alkyl ethers of polyhydric alcohols, and aliphatic amides of alkanolamines. Examples of anionic surfactants include sulfate ester salts such as alkali metal salts of higher fatty acids, sulfonates such as alkylbenzene sulfonates, alkyl sulfonates, and paraffin sulfonates, and phosphate ester salts such as higher alcohol phosphate esters. Examples of cationic surfactants include quaternary ammonium salts such as alkyltrimethylammonium salts. Examples of amphoteric surfactants include amino acid-type amphoteric surfactants such as higher alkylaminopropionates, and betaine-type amphoteric surfactants such as higher alkyldimethyl betaine and higher alkyl hydroxyethyl betaine. These surfactants may be used individually or in combination of two or more types.

[0073] Furthermore, the resin composition of the present invention may contain various additives as needed, to the extent that it does not impair the effects of the present invention, such as ultraviolet absorbers, nucleating agents, pigments, hydrochloric acid absorbers, crosslinking agents, crosslinking aids, softeners, and flame retardants. One or more of these additives may be used.

[0074] The content of the above-mentioned antioxidant, antistatic agent, and various additives is preferably 5 parts by mass or less, more preferably 4 parts by mass or less, and even more preferably 2 parts by mass or less, per 100 parts by mass of the total of 4-methyl-1-pentene·α-olefin copolymer (A), propylene elastomer (B), and homopolypropylene (C).

[0075] Furthermore, the resin composition of the present invention may contain resins other than 4-methyl-1-pentene·α-olefin copolymer (A), propylene-based elastomer (B), and homopolypropylene (C), to the extent that the effects of the present invention are not impaired. The content of the resin is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, based on 100 parts by mass of the total of 4-methyl-1-pentene·α-olefin copolymer (A), propylene-based elastomer (B), and homopolypropylene (C).

[0076] [Laminated film] The laminated film of the present invention is a film in which a surface layer (X), an intermediate layer (Y), and a backing layer (Z) are laminated in this order. The intermediate layer (Y) contains the resin composition of the present invention described above, and the surface layer (X) and backing layer (Z) contain the homopolypropylene (C).

[0077] The homopolypropylene (C) used for the surface layer (X) may be the same homopolypropylene as the backing layer (Z), or a different homopolypropylene may be used. Furthermore, the surface layer (X) and the back layer (Z) may, if necessary, contain antioxidants, antistatic agents, and various additives, similar to those in the resin composition of the present invention.

[0078] The laminated film may include layers other than the surface layer (X), intermediate layer (Y), and backing layer (Z). For example, to improve interlayer adhesion strength, adhesive layers can be provided between the surface layer (X) and the intermediate layer (Y), and between the intermediate layer (Y) and the backing layer (Z).

[0079] The thickness of the laminated film is not particularly limited and can be appropriately selected according to the desired application, but is preferably 10 to 300 μm, more preferably 20 to 200 μm, even more preferably 30 to 150 μm, and particularly preferably 40 to 120 μm. If the thickness is above the lower limit, the film has sufficient rigidity and is easy to handle during film manufacturing and use. If the thickness is below the upper limit, when the laminated film is used in the semiconductor manufacturing process, it has good conformability and is easy to handle in processes such as the dicing process, where the dicing film is set on a ring frame, attached and fixed, and then cut into chip shapes, and the expanding process, where the dicing film is expanded to separate each chip. Furthermore, the mass of the laminated film is not too large, and the laminated film has appropriate rigidity, resulting in good productivity in film manufacturing.

[0080] From the viewpoint of handling dicing films used in semiconductor manufacturing processes, the ratio of the thickness of the surface layer (X) / intermediate layer (Y) / backing layer (Z) (thickness of the surface layer (X) / thickness of the intermediate layer (Y) / thickness of the backing layer (Z)) is preferably 1 / 12 / 1 to 1 / 20 / 1, and more preferably 1 / 14 / 1 to 1 / 18 / 1. If the ratio of the thickness of the surface layer (X) / intermediate layer (Y) / backing layer (Z) is greater than or equal to the lower limit above, the laminated film exhibits good conformability during the dicing and expanding processes. If the ratio of the thickness of the surface layer (X) / intermediate layer (Y) / backing layer (Z) is less than or equal to the upper limit above, the laminated film does not stretch excessively and obtains appropriate tensile strength, making it easy to handle during the expanding process, in which the dicing film is expanded to separate the chips.

[0081] <Method for manufacturing laminated film> The laminated film can be manufactured by molding it using a known extruder. For example, it can be manufactured by a feed block method in which resins or resin compositions that constitute each layer are melt-extruded using two or more extruders, or by a co-extruder T-die method such as a multi-manifold method, or by an air-cooled or water-cooled co-extrusion inflation method. Among these methods, the co-extruder T-die method is preferred because it allows for easy adjustment of the thickness of the laminated film and provides suitable interlayer adhesion strength for both the surface / intermediate layer and the intermediate / back layer. Specifically, it can be manufactured by using three extruders connected to T-dies, supplying the resins constituting the surface and back layers, and the resin composition constituting the intermediate layer, to each extruder, and performing co-extrusion molding.

[0082] The laminated film may have an adhesive applied to one side of either the front layer (X) or the back layer (Z) as a dicing film used in semiconductor manufacturing processes. The surface to which the adhesive is applied may be subjected to a surface treatment such as corona treatment, and the surface that has been surface-treated will have improved adhesion to the adhesive. For application of the adhesive, the adhesive may be diluted with a solvent such as toluene, acetone, methyl ethyl ketone, or dimethyl formaldehyde, and applied by methods such as die coating, gravure coating, curtain coating, bar coating, comma coating, or lip coating. Additionally, a separator may be attached to the adhesive surface of the dicing film as needed.

[0083] <Physical properties of laminated films> The laminated film of the present invention is a multilayer film containing the resin composition as an intermediate layer (Y), and its tensile modulus is preferably 200 to 1000 MPa at 23°C and a test speed of 500 mm / min, as measured in accordance with JIS K7127. The value of the tensile modulus indicates the rigidity of the laminated film.

[0084] The tensile modulus of the laminated film of the present invention is more preferably 200 to 800 MPa, even more preferably 220 to 700 MPa, and particularly preferably 240 to 600 MPa. When the tensile modulus of the laminated film is within the above range, it has appropriate tensile strength. Specifically, it becomes easier to handle when used in the expansion process, in which the dicing film is expanded to separate each chip, and in the pickup process, in which each chip is acquired. If the tensile modulus is below the above lower limit, the force during expansion is not sufficiently transmitted to the semiconductor (semiconductor wafer), resulting in poor divisibility of the semiconductor. Furthermore, if the tensile modulus is above the above upper limit, the problem arises that excessive load is placed on the dice separator device used to expand the dicing film. In addition, heat shrinkage (heat shrinkage and restoration) is used to eliminate sagging of the dicing film after the expansion process, but if the tensile modulus is above the above upper limit, it becomes difficult to heat shrink, resulting in a low restoration rate.

[0085] The laminated film of the present invention preferably has a difference of 2.0 MPa or less in tensile stress between the MD direction (Machine Direction) and the TD direction (Traverse Direction) when measured in accordance with JIS K7127 at 23°C, a test speed of 500 mm / min, and a strain of 20%. The smaller the difference in tensile stress between the MD direction and the TD direction, the more uniformly the laminated film can be stretched.

[0086] In the laminated film of the present invention, when measured in accordance with JIS K7127 at 23°C, a test speed of 500 mm / min, and a strain of 20%, the difference in tensile stress between the MD direction and the TD direction is more preferably 1.5 MPa or less, even more preferably 1.2 MPa or less, and particularly preferably 1.0 MPa or less. If the difference in tensile stress between the MD direction and the TD direction of the laminated film is within the above range, it can be stretched uniformly and precisely in all directions.

[0087] The laminated film of the present invention preferably has a stress relaxation rate of 30% or more, as shown in the following formula (1), when the load immediately after 20% elongation is G, measured in accordance with JIS K7127 at 23°C and a test speed of 500 mm / min, and the load when held for 3 minutes is H. {(GH) / G} × 100 ···(1) The stress relaxation rate of the laminated film is more preferably 35% or higher, and even more preferably 40% or higher. When the stress relaxation rate of the laminated film is within the above range, it can slowly return to its original dimensions after being stretched and stress released, so that the pickup process for acquiring each chip when using a dicing film in semiconductor manufacturing can be operated stably and without trouble.

[0088] Dicing films are also frequently used in the expansion process. In the expansion process, it is necessary to form uniform gaps between each chip, so the dicing film must have the characteristic of stretching in all directions. However, if a yield point exists when the dicing film is stretched, it becomes impossible to create uniform and precise gaps between each chip in the expansion process, leading to problems in semiconductor manufacturing. [Examples]

[0089] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. The methods for measuring the physical properties of the resin, the resins used, the methods for preparing test pieces, and the evaluation methods in the following examples and comparative examples are as follows.

[0090] ≪Methods for measuring the physical properties of polymers≫ <Content of constituent units> The amount of constituent units derived from 4-methyl-1-pentene and the amount of constituent units derived from α-olefin in copolymer (A) are determined by the following apparatus and conditions. 13 The amount was calculated from the 1C-NMR spectrum. However, the amount of constituent units derived from α-olefins in this measurement result does not include the amount of constituent units derived from 4-methyl-1-pentene. Using a nuclear magnetic resonance spectrometer (ECP500, manufactured by JEOL Ltd.), a mixed solvent of o-dichlorobenzene / deuterated benzene (80 / 20 vol%) was used, with a sample concentration of 55 mg / 0.6 mL, a measurement temperature of 120°C, and the observed nuclei were 13 The measurement was performed using C (125 MHz), a single-pulse proton decoupling sequence, a pulse width of 4.7 μs (45° pulse), a repetition time of 5.5 seconds, and an accumulation count of over 10,000 times, with 27.50 ppm as the reference value for chemical shift. 13 The composition of copolymer (A) was quantified by 13C-NMR spectroscopy.

[0091] <Intrinsic viscosity> The intrinsic viscosity of copolymer (A) was determined using an Ubbelohde viscometer at 135°C in decalin solvent. Approximately 20 mg of sample was taken for each copolymer (A). The sample may be in the form of polymerization powder, pellets, or resin lumps. The copolymer was dissolved in 15 mL of decalin, and the specific viscosity ηsp was measured in an oil bath heated to 135°C. After diluting this decalin solution by adding 5 mL of decalin solvent, the specific viscosity ηsp was measured again in the same manner. This dilution procedure was repeated two more times, and the intrinsic viscosity was calculated as the ηsp / C value when the concentration (C) was extrapolated to zero (see formula below). [η] = lim(ηsp / C) (C→0)

[0092] <Weight-average molecular weight (Mw), number-average molecular weight (Mn), molecular weight distribution (Mw / Mn value)> The molecular weight of copolymer (A) was measured by gel permeation chromatography (GPC). Specifically, a Waters ALC / GPC150-Cplus liquid chromatograph (integrated differential refractometer detector) was used, with two Tosoh GMH6-HT columns and two GMH6-HTL columns connected in series as the separation columns. o-dichlorobenzene was used as the mobile phase medium, and 0.025% by mass of dibutylhydroxytoluene (Takeda Pharmaceutical Company Limited) was used as the antioxidant. The mobile phase medium was moved at 1.0 mL / min, the sample concentration was 15 mg / 10 mL, the sample injection volume was 500 μL, and a differential refractometer was used as the detector. For the standard polystyrene, Tosoh standard polystyrene with a weight-average molecular weight (Mw) between 1,000 and 4,000,000 was used. The obtained chromatograms were analyzed by creating calibration curves using standard polystyrene samples using known methods to calculate the weight-average molecular weight (Mw), number-average molecular weight (Mn), and molecular weight distribution (Mw / Mn value). The measurement time per sample was 60 minutes.

[0093] <Meltflow Rate (MFR)> The MFR of copolymer (A) was measured in accordance with ASTM D1238 at a temperature of 230°C and a load of 2.16 kgf.

[0094] <Melting point (Tm)> The melting point (Tm) of copolymer (A) was determined in accordance with JIS K7121 using a differential scanning calorimeter (Hitachi High-Tech DSC200). Approximately 5 mg of the sample was placed in an aluminum pan for measurement and heated to 200°C at a heating rate of 10°C / min. The temperature of the highest melting peak among the measured melting peaks was defined as the melting point. If no melting peak appeared, it was evaluated as not being observed.

[0095] <density> The density of copolymer (A) was measured using a density gradient tube in accordance with JIS K7112.

[0096] <Dynamic Viscoelasticity Measurement> After filling a predetermined amount of pelletized copolymer (A) into a SUS mold, the heating plate was set to 200°C, and using a hydraulic hot press (NSF-50 manufactured by Shinto Metal Industries Co., Ltd.), the material was preheated for 7 minutes, pressurized at a gauge pressure of 10 MPa for 2 minutes, then transferred to a cooling plate set to 20°C, compressed at a gauge pressure of 10 MPa, and cooled for 2 minutes to produce a 2 mm thick measuring press sheet.

[0097] Using the aforementioned press sheet for measurement, the temperature dispersion of dynamic viscoelasticity from -40 to 150°C was observed using a rheometer (Anton Paar MCR301) under the conditions of torsion mode (torsional deformation), frequency: 1.0 Hz, heating rate: 4°C / min, and strain amount: 0.5%, and the tanδ peak value and tanδ peak temperature were measured.

[0098] Resin used <Preparation Example 1: Preparation of Copolymer (A-1)> A 1.5 L stainless steel autoclave with stirring blades, thoroughly purged with nitrogen, was charged with 300 mL of n-hexane (dried on activated alumina under a dry nitrogen atmosphere) and 450 mL of 4-methyl-1-pentene at 23°C. 0.75 mL of a 1.0 mmol / mL toluene solution of triisobutylaluminum (TIBAL) was then added to the autoclave and stirred.

[0099] Next, the autoclave was heated to an internal temperature of 60°C and pressurized with propylene to a total pressure (gauge pressure) of 0.40 MPa. Subsequently, 0.34 mL of a toluene solution containing 1 mmol of methylaluminoxane (aluminum equivalent) and 0.01 mmol of diphenylmethylene (1-ethyl-3-t-butyl-cyclopentadienyl)(2,7-di-t-butyl-fluorenyl)zirconium dichloride, which had been prepared in advance, was injected into the autoclave under nitrogen pressure to start the polymerization reaction. During the polymerization reaction, the temperature of the autoclave was adjusted to maintain an internal temperature of 60°C. 60 minutes after the start of polymerization, 5 mL of methanol was injected into the autoclave under nitrogen pressure to stop the polymerization reaction, and then the autoclave was depressurized to atmospheric pressure. After depressurization, acetone was added to the reaction solution while stirring.

[0100] The resulting solvent-containing powdered copolymer was dried at 100°C under reduced pressure for 12 hours. The mass of the product copolymer (A-1) was 36.9 g. In copolymer (A-1), the content of structural units derived from 4-methyl-1-pentene was 72.4 mol%, and the content of structural units derived from propylene was 27.6 mol%. DSC measurement revealed no melting point. The measurement results for each physical property of copolymer (A-1) are shown in Table 1.

[0101] Next, 0.1 parts by mass of tetrakis[3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionic acid]pentaerythritol as a heat-resistant stabilizer and 0.1 parts by mass of tris(2,4-di-t-butylphenyl) phosphate as a secondary antioxidant were added to 100 parts by mass of the copolymer (A-1). Using a twin-screw extruder (TEX25αIII, manufactured by Japan Steel Works Ltd., screw diameter 25 mm, L / D=52), the strand was discharged under the conditions of a cylinder setting temperature of 200°C, an extrusion rate of 5 kg / hour, and a screw rotation speed of 100 rpm. The strand was then guided to a pelletizer (KM-100, manufactured by Katsumic Co., Ltd.) while immersed in a water bath for granulation to obtain pellets. The results of dynamic viscoelasticity measurements using the pellets are shown in Table 1.

[0102] <Preparation Example 2: Preparation of Copolymer (A-2)> A 1.5 L stainless steel autoclave with a stirring blade, thoroughly purged with nitrogen, was charged with 300 mL of n-hexane (dried on activated alumina under a dry nitrogen atmosphere) and 450 mL of 4-methyl-1-pentene at 23°C. 0.75 mL of a 1.0 mmol / mL toluene solution of triisobutylaluminum (TIBAL) was then added to the autoclave and stirred.

[0103] Next, the autoclave was heated to an internal temperature of 60°C and pressurized with propylene to a total pressure (gauge pressure) of 0.19 MPa. Subsequently, 0.34 mL of a toluene solution containing 1 mmol of methylaluminoxane (aluminum equivalent) and 0.01 mmol of diphenylmethylene (1-ethyl-3-t-butyl-cyclopentadienyl)(2,7-di-t-butyl-fluorenyl)zirconium dichloride, which had been prepared in advance, was injected into the autoclave under nitrogen pressure to start the polymerization reaction. During the polymerization reaction, the temperature of the autoclave was adjusted to maintain an internal temperature of 60°C. 60 minutes after the start of polymerization, 5 mL of methanol was injected into the autoclave under nitrogen pressure to stop the polymerization reaction, and then the autoclave was depressurized to atmospheric pressure. After depressurization, acetone was added to the reaction solution while stirring.

[0104] The resulting solvent-containing powdered copolymer was dried at 130°C under reduced pressure for 12 hours. The mass of the product copolymer (A-2) was 44.0 g. In copolymer (A-2), the content of structural units derived from 4-methyl-1-pentene was 84.1 mol%, and the content of structural units derived from propylene was 15.9 mol%. DSC measurement revealed a melting point of 130°C. The measurement results for each physical property of copolymer (A-2) are shown in Table 1.

[0105] Next, 0.1 parts by mass of tetrakis[3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionic acid]pentaerythritol as a heat-resistant stabilizer and 0.1 parts by mass of tris(2,4-di-t-butylphenyl)phosphate as a secondary antioxidant were added to 100 parts by mass of the copolymer (A-2). Using a twin-screw extruder (TEX25αIII, manufactured by Japan Steel Works Ltd., screw diameter 25 mm, L / D=52), the strand was discharged under the conditions of a cylinder setting temperature of 200°C, an extrusion rate of 5 kg / hour, and a screw rotation speed of 100 rpm. The strand was then guided to a pelletizer (KM-100, manufactured by Katsumic Co., Ltd.) while immersed in a water bath for granulation to obtain pellets. The results of dynamic viscoelasticity measurements using the pellets are shown in Table 1.

[0106] <Propylene-based elastomer (B)> As a propylene-based elastomer (B), we used Toughmer PN-3560 manufactured by Mitsui Chemicals, Inc. (MFR = 6.0 g / 10 min, density 866 kg / m³). 3 (A material with a melting point of 160°C, Shore A hardness of 72, and glass transition temperature of -29°C was used.)

[0107] <Homopolypropylene (C)> As homopolypropylene (C), Prime PolyPro F107BV manufactured by Prime Polymer Co., Ltd. (MFR = 7g / 10 min (230℃, 2.16kg), melting point 160℃) was used.

[0108] [Table 1]

[0109] Physical property evaluation of laminated films <Tensile modulus> Strip-shaped test pieces measuring 10 mm wide x 100 mm long were taken from the MD direction and TD direction of the laminated film, respectively. Next, the tensile modulus was measured five times using a tensile testing machine (Shimadzu Autograph AG-500N) in accordance with JIS K7127, at 23°C, a grip distance of 50 mm, and a test speed of 500 mm / min, and the average of the measured values ​​was calculated.

[0110] <Yield point tensile stress and yield point elongation> Strip-shaped test pieces measuring 10 mm wide x 100 mm long were taken from the MD and TD directions of the laminated film. Next, five measurements were taken using a tensile testing machine (Shimadzu Autograph AG-500N) in accordance with JIS K7127, at 23°C, a grip distance of 50 mm, and a test speed of 500 mm / min. If a yield point was observed, the average value was calculated from the measured tensile stress and elongation. If no yield point was observed, it was recorded as "not observed".

[0111] <Tensile stress at 20% elongation> Test specimens measuring 10 mm wide x 100 mm long were taken from the MD and TD directions of the laminated film. Next, using a tensile testing machine (Shimadzu Autograph AG-500N), the tensile stress at which the elongation reached 20% was measured five times in accordance with JIS K7127 at 23°C, a grip distance of 50 mm, and a test speed of 500 mm / min, and the average was calculated. Furthermore, the difference between the average values ​​in the MD and TD directions (Δ(MD-TD)) was determined.

[0112] <Stress relaxation rate at 20% extension> Test specimens measuring 10 mm in width and 100 mm in length were taken from the MD direction and TD direction of the laminated film. Next, using a tensile testing machine (Shimadzu Autograph AG-500N), under conditions of 23°C, grip distance of 50 mm, and test speed of 500 mm / min in accordance with JIS K7127, the load immediately after the elongation reached 20% was defined as G, and the load after holding for 3 minutes was defined as H. The value calculated using the following formula (1) was defined as the stress relaxation rate (%). {(GH) / G} × 100 ···(1)

[0113] [Example 1] Resin composition 1 was prepared by mixing (dry blending) 30 parts by mass of copolymer (A-1), 30 parts by mass of propylene elastomer (B), and 40 parts by mass of homopolypropylene (C) using a tumbler blender.

[0114] <Fabrication of laminated films> Homopolypropylene (C) was placed in the surface layer hopper, resin composition 1 in the intermediate layer hopper, and homopolypropylene (C) in the back layer hopper of a three-layer co-extrusion molding machine equipped with a T-die (screw diameter 25 mm, L / D = 24, T-die width 350 mm, lip opening 2 mm). The cylinder temperature was set to 220-240°C and the T-die temperature to 240°C, and molten resin was extruded from the T-die. The casting roll temperature was set to 40°C and the take-up speed to 3.0 m / min, and a laminated film was obtained by adjusting the screw rotation speed so that the thickness of the surface layer (X), intermediate layer (Y), and back layer (Z) were 5 μm, 70 μm, and 5 μm, respectively. The physical properties of the laminated film were measured according to the method described above. The results are shown in Table 2.

[0115] [Example 2] A resin composition 2 was prepared using 40 parts by mass of copolymer (A-1), 40 parts by mass of propylene elastomer (B), and 20 parts by mass of homopolypropylene (C). A laminated film was prepared in the same manner as in Example 1, except that resin composition 2 was used instead of resin composition 1. The results of the physical property measurements of the laminated film are shown in Table 2.

[0116] [Example 3] Resin composition 3 was prepared using 30 parts by mass of copolymer (A-2), 50 parts by mass of propylene elastomer (B), and 20 parts by mass of homopolypropylene (C). A laminated film was prepared in the same manner as in Example 1, except that resin composition 3 was used instead of resin composition 1. The results of the physical property measurement of the laminated film are shown in Table 2.

[0117] [Example 4] A resin composition 4 was prepared using 40 parts by mass of copolymer (A-2), 50 parts by mass of propylene-based elastomer (B), and 10 parts by mass of homopolypropylene (C). A laminated film was prepared in the same manner as in Example 1, except that resin composition 4 was used instead of resin composition 1. The results of the physical property measurements of the laminated film are shown in Table 2.

[0118] [Comparative Example 1] A resin composition 5 was prepared using 50 parts by mass of copolymer (A-1) and 50 parts by mass of copolymer (A-2). A laminated film was prepared in the same manner as in Example 1, except that resin composition 5 was used instead of resin composition 1. The results of the physical property measurements of the laminated film are shown in Table 2.

[0119] [Comparative Example 2] A resin composition 6 was prepared using 50 parts by mass of copolymer (A-2) and 50 parts by mass of propylene-based elastomer (B). A laminated film was prepared in the same manner as in Example 1, except that resin composition 6 was used instead of resin composition 1. The results of the physical property measurements of the laminated film are shown in Table 2.

[0120] [Comparative Example 3] A resin composition 7 was prepared using 50 parts by mass of copolymer (A-1) and 50 parts by mass of homopolypropylene (C). A laminated film was prepared in the same manner as in Example 1, except that resin composition 7 was used instead of resin composition 1. The results of the physical property measurements of the laminated film are shown in Table 2.

[0121] [Table 2]

[0122] Examples 1 to 4, which used the laminated film of the present invention, exhibited uniform elongation in the MD and TD directions, with the yield point disappearing and possessing appropriate tensile strength. Furthermore, stress relaxation properties of 40% or more were observed, suggesting that the film slowly returned to its original dimensions after the release of tensile stress. On the other hand, Comparative Examples 1 to 3 did not satisfy all of the above requirements. [Industrial applicability]

[0123] The laminated film of the present invention is suitably used as a dicing film in semiconductor manufacturing processes. It is also suitable as a dicing film used in stealth dicing, in which a modified layer is formed inside a semiconductor wafer by irradiating it with laser light, the dicing film is expanded, and the semiconductor wafer is separated from the modified layer.

Claims

1. 20 to 50 parts by mass of a 4-methyl-1-pentene / α-olefin copolymer (A) that satisfies the following requirements (A-a) to (A-d), 20 to 60 parts by mass of a propylene-based elastomer (B) that satisfies the following requirements (B-a) to (B-d), Homopolypropylene (C) 5 to 50 parts by mass, A resin composition containing (wherein the total of copolymer (A), propylene elastomer (B), and homopolypropylene (C) is 100 parts by mass). Requirements (A-a): Consists of 60-90 mol% of constituent unit (i) derived from 4-methyl-1-pentene and 10-40 mol% of constituent unit (ii) derived from α-olefins having 2-4 carbon atoms (provided that the sum of constituent unit (i) and constituent unit (ii) is 100 mol%). Requirement (A-b): The intrinsic viscosity [η] measured in decalin at 135°C is in the range of 0.5 to 5.0 dl / g. Requirement (A-c): The melting point (Tm) measured by differential scanning calorimeter (DSC) is not observed or is in the range of less than 160°C. Requirements (A-d): Density of 820-860 kg / m³ 3 It is within the range. Requirement (B-a): The melting point (Tm) measured by differential scanning calorimeter (DSC) is in the range of 130 to 170°C. Requirement (B-b): The glass transition temperature (Tg), as measured by a differential scanning calorimeter (DSC), is in the range of -25 to -35°C. Requirement (B-c): The Shore A hardness, as measured by ASTM D2240, is in the range of 65 to 90. Requirement (B-d): Density of 860-875 kg / m³ 3 It is within the range.

2. A laminated film in which the surface layer (X) / intermediate layer (Y) / back layer (Z) are stacked in that order, The surface layer (X) and the back layer (Z) contain homopolypropylene (C). The intermediate layer (Y) is a laminated film containing the resin composition described in claim 1.

3. The laminated film according to claim 2, wherein the tensile modulus of elasticity is 200 to 1000 MPa at 23°C and a test speed of 500 mm / min, as measured in accordance with JIS K7127.

4. The laminated film according to claim 2, wherein, as measured in accordance with JIS K7127, at 23°C, a test speed of 500 mm / min, and a strain of 20%, the difference in tensile stress between the MD direction and the TD direction is 2.0 MPa or less.

5. The laminated film according to claim 2, wherein, when measured in accordance with JIS K7127 at 23°C, at a test speed of 500 mm / min, with the load immediately after 20% elongation being G and the load after holding for 3 minutes being H, the stress relaxation rate shown by the following formula (1) is 30% or more. {(GH) / G}×100...(1)

6. The laminated film according to claim 2, wherein the yield point measured in accordance with JIS K7127 at 23°C and a test speed of 500 mm / min is not observed in either the MD direction or the TD direction.

7. A laminated film according to any one of claims 2 to 6, used in a semiconductor manufacturing process.

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