JP6878956B2 - the film - Google Patents

Description

The present invention relates to a film and a method for producing a film.

Conventionally, highly flexible film members that can be stretched with a low load even at room temperature have been applied as various products such as base materials such as adhesive tapes, transfer base materials for molding, and cushioning materials during pressing. However, it is used in a wide range of fields such as circuits and semiconductor manufacturing processes and decorations.

For example, in the process of manufacturing a semiconductor, a step of attaching an adhesive tape for semiconductor wafer processing to the pattern surface of a semiconductor wafer, a back grind step of polishing the back surface of the semiconductor wafer to reduce the thickness, and a process of reducing the thickness in the process. There are various steps such as a step of mounting the semiconductor wafer on the dicing tape, a step of peeling the adhesive tape for processing the semiconductor wafer from the semiconductor wafer, and a step of dividing the semiconductor wafer by dying.

In recent years, semiconductor wafers have become thinner with the miniaturization of electronic devices, and their strength has decreased. Therefore, they are easily damaged during these manufacturing processes, and a decrease in yield has become an issue. For example, there is a demand for a highly flexible adhesive film that reduces the load on a semiconductor wafer, which occurs in the process of radially expanding a dicing adhesive film and picking up individual chips after the dicing step. As a method for increasing the flexibility of the pressure-sensitive adhesive film, for example, a film containing a resin having excellent flexibility such as a polypropylene-based resin, an olefin-based elastomer, and a styrene-based elastomer as a main component is used as a base film for the pressure-sensitive adhesive film. The method to be used is known (Patent Document 1).

Further, a step of attaching a dicing adhesive film to the surface of the semiconductor wafer polished in the back grind step and peeling the back grind sheet by thermal peeling may be used. At that time, if the dimensional stability of the adhesive film for dicing that is heated at the same time is insufficient, there is a problem that the film is deformed, causing wrinkles and slack. To solve such a problem, for example, a film having controlled heat shrinkage has been proposed as a base material of an adhesive film for a dicing tape (Patent Document 2).

Japanese Unexamined Patent Publication No. 2011-119548 Japanese Unexamined Patent Publication No. 2014-157964

However, since the base material used for the adhesive tape described in Patent Document 1 and Patent Document 2 is a non-stretched film obtained by an extrusion method, there is a problem that the film expands under tension and loses the flatness of the film. is there. Further, a non-stretched film conventionally used as a base film such as an adhesive film for dicing is difficult to be applied to semiconductor manufacturing process applications because the film expands when heated under a low load. On the other hand, a film having high dimensional stability such as a biaxially stretched film can reduce deformation during heating, but lacks flexibility, so that it is similarly difficult to apply to the same application. As described above, conventionally known films cannot achieve both heat resistance and flexibility required for a substrate for a semiconductor manufacturing process, and improvement has been desired.

The present invention solves the above-mentioned problems of the prior art, has heat resistance to the extent that flatness can be maintained in the heating process, and has sufficient flexibility to be used as an adhesive film for dicing and the like. An object of the present invention is to provide a film suitable as a base material for a semiconductor manufacturing process.

In order to solve such a problem, the present invention has the following configuration.
(1) The main component is a polyester elastomer, and the layer having a glass transition temperature of -100 ° C or higher and 0 ° C or lower is mainly composed of one resin selected from the group consisting of layer A, polyethylene terephthalate, polybutylene terephthalate, and polyester elastomer. When the layer having a glass transition temperature of more than 0 ° C. and 100 ° C. or lower is defined as the B layer, it has A layer and B layer, and at least one surface orientation coefficient is 0.0080 or more and 0.0800 or less. Ah is, 5% elongation during stress at 25 ° C., and wherein the der Rukoto least 20MPa or less 1MPa at a maximum, the film.
(2) A layer containing an olefin elastomer as a main component and having a glass transition temperature of -100 ° C or higher and 0 ° C or lower is a layer A, and a layer containing polypropylene as a main component and having a glass transition temperature of more than 0 ° C and 100 ° C or lower is B. When used as a layer, it has layers A and B, has at least one surface orientation coefficient of 0.0080 or more and 0.0800 or less, and has a maximum stress during 5% elongation at 25 ° C. of 1 MPa or more and 20 MPa or less. A film characterized by being.
(3) The dimensional change rate at 90 ° C. when the temperature is raised from 25 ° C. to 160 ° C. at a heating rate of 10 ° C./min is the 90 ° C. dimensional change rate, and the direction in which the 90 ° C. dimensional change rate is maximum is the X direction. The film according to (1) or (2), wherein the Tx is −10% or more and 1% or less when the dimensional change rate at 90 ° C. in the direction is Tx (%).
(4) When the direction orthogonal to the X direction in the film plane is the Y direction and the 90 ° C. dimensional change rate in the Y direction is Ty (%), the Tx and Ty satisfy the following formula 1. The film according to (3).
Equation 1: 0.1 ≤ | Tx-Ty | ≤ 3.0
(5) The film according to any one of (1) to (4), wherein the B layer, the A layer, and the B layer are located in this order.
(6) The film according to any one of (1) to (5), wherein the B layer is located on at least one of the outermost surfaces.
(7) The film according to any one of (1) to (6), wherein the coefficient of static friction measured by superimposing different surfaces of the film is 0.1 or more and 0.8 or less.
(8) The melt flow rate MFRa (g / 10 minutes) under the conditions of the melting point of the resin which is the main component of the A layer + 20 ° C. and the load of 5.0 kgf is 5 or more and 20 or less, and the main component of the B layer is The melt flow rate MFRb (g / 10 minutes) under the conditions of the melting point of the resin as a component + 20 ° C. and a load of 5.0 kgf is 10 or more and 25 or less, and MFRa and MFRb satisfy the following formula 2. The film according to any one of (1) to (7).
Equation 2: 0 ≦ | MFRb-MFRa | ≦ 5
(9) The method for producing a film according to any one of (1) to (8), which comprises a step of stretching in at least one direction at a magnification of 1.04 times or more and 1.50 times or less.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a film having both flexibility and heat resistance and a method for producing the same, and the film of the present invention can be suitably used as a base material for a semiconductor manufacturing process.

In the film of the present invention, when the layer having a glass transition temperature of -100 ° C or higher and 0 ° C or lower is the A layer and the layer having the glass transition temperature of more than 0 ° C and 100 ° C or lower is the B layer, the A layer and B are used. It is characterized by having a layer and having a plane orientation coefficient of at least one side of 0.0080 or more and 0.0800 or less.

In the film of the present invention, when the layer having a glass transition temperature of -100 ° C. or higher and 0 ° C. or lower is the A layer, and the layer having the glass transition temperature of more than 0 ° C. and 100 ° C. or lower is the B layer, the A layer and B are used. It is important to have a layer. By having the A layer having a glass transition temperature of −100 ° C. or higher and 0 ° C. or lower, the film has sufficient flexibility even at room temperature. Further, by having the B layer having a glass transition temperature of more than 0 ° C. and 100 ° C. or lower, it is within an appropriate range to realize the flexibility and heat resistance which are the objects of the present invention by combining with the microstretching step described later. The orientation state of the molecule can be controlled. Here, the glass transition temperature means a temperature obtained based on the measurement of the calorific value change (DSC method) by the differential scanning calorimetry (DSC) in accordance with JIS K7121: 2012.

From the viewpoint of achieving both flexibility and heat resistance, the glass transition temperature of the A layer is preferably −90 ° C. or higher and −20 ° C. or lower, and more preferably −85 ° C. or higher and −40 ° C. or lower. From the same viewpoint, the glass transition temperature of the B layer is preferably 20 ° C. or higher and 90 ° C. or lower, more preferably 30 ° C. or higher and 85 ° C. or lower.

The resin used for the A layer and the B layer is not particularly limited as long as the effect of the present invention is not impaired, and for example, polyesters such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, polyarylate, polyethylene, polypropylene, polyamide, polyimide, Polymethylpentene, polyvinyl chloride, polystyrene, polymethylmethacrylate, polycarbonate, polyetheretherketone, polysulphon, polyethersulfon, fluororesin, polyetherimide, polyphenylene sulfide, polyurethane, cyclic olefin resin, etc. alone or in combination. Can be used in combination. Of these, polyesters such as polyethylene terephthalate and polybutylene terephthalate are preferably used from the viewpoints of film handleability, dimensional stability, and economic efficiency during production.

In the present invention, polyester is a general term for polymers having an ester bond as a major bond in the main chain. Usually, polyester can be obtained by polycondensing a dicarboxylic acid component and a glycol component.

The dicarboxylic acid component for obtaining a polyester is not particularly limited as long as the effects of the present invention are not impaired, and for example, terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid. , Aromatic dicarboxylic acids such as diphenoxyetanedicarboxylic acid, 5-sodium sulfonate dicarboxylic acid, aliphatic dicarboxylic acids such as oxalic acid, succinic acid, adipic acid, sebacic acid, dimer acid, maleic acid, fumaric acid, 1,4 -Each component such as an alicyclic dicarboxylic acid such as cyclohexanedicarboxylic acid and an oxycarboxylic acid such as paraoxybenzoic acid can be used. Further, the dicarboxylic acid component may be a dicarboxylic acid ester derivative component, and an esterified product of the above dicarboxylic acid compound, for example, dimethyl terephthalate, diethyl terephthalate, 2-hydroxyethylmethyl ester terephthalic acid, 2,6-naphthalenedicarboxylic acid. Each component such as dimethyl, dimethyl isophthalate, dimethyl adipate, diethyl maleate, and dimethyl dimerate can also be used.

Further, the glycol component for obtaining polyester is not particularly limited as long as the effect of the present invention is not impaired, and for example, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, and the like. Aliphatic dihydroxy compounds such as 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetra Each component can be used, such as polyoxyalkylene glycol such as methylene glycol, alicyclic dihydroxy compound such as 1,4-cyclohexanedimethanol and spiroglycol, and aromatic dihydroxy compound such as bisphenol A and bisphenol S. Among them, ethylene glycol, 1,4-butanediol, 2,2-dimethyl-1,3-propanediol, 1,4-cyclohexanedimethanol, and poly in terms of both flexibility and heat resistance and handleability. It is preferable to use each component of tetramethylene glycol.

Two or more of these dicarboxylic acid components and glycol components may be used in combination as long as the effects of the present invention are not impaired.

The method of setting the glass transition temperature of the A layer to −100 ° C. or higher and 0 ° C. or lower or the above-mentioned preferable range is not particularly limited as long as the effect of the present invention is not impaired, but the glass transition temperature of the resin constituting the A layer is high. Examples thereof include a method of using -100 ° C. or higher and 0 ° C. or lower, or those in the above preferable range. The glass transition temperature of the A layer is increased by setting the resin constituting the A layer to have a high glass transition temperature and increasing the ratio of the resin having a high glass transition temperature to the entire resin constituting the A layer. be able to. The same applies to the method of setting the glass transition temperature of the B layer to more than 0 ° C. and 100 ° C. or lower, or the above-mentioned preferable range. Specifically, the A layer is a layer mainly composed of a resin having a glass transition temperature of −90 ° C. or higher and −20 ° C. or lower, and the B layer is mainly composed of a resin having a glass transition temperature of 20 ° C. or higher and 90 ° C. or lower. The method of forming the layer is preferably used. The main component here means a component that occupies 50% by mass or more when the total of the resin components constituting the layer is 100% by mass. Hereinafter, the main components can be interpreted in the same manner.

It is important that the film of the present invention has a plane orientation coefficient of at least one side of 0.0080 or more and 0.0800 or less. The plane orientation coefficient (fn) referred to here means a plane orientation coefficient measured by the following method. First, the arbitrary direction parallel to the film plane is α, the direction orthogonal to this in the film plane is β, α and the direction orthogonal to β (thickness direction) is γ, and the refractive indexes in each direction (nα, nβ, nγ) is measured with an Abbe refractive index meter. _{Using each of the obtained values, the plane orientation coefficient (fn 0} ) when the two directions on the film surface are α and β is obtained by the following equation 3.
Equation 3: fn ₀ = (nα + nβ) / 2-nγ
Next, γ is fixed and α and β are rotated clockwise by 5 ° while maintaining parallelism with the film surface to obtain nα5 and nβ5, and the refractive index (nα5, nβ5, nγ) in each direction is Abbe. It is measured with a refractive index meter, and nα in the above formula 3 is replaced with nα5 and nβ is replaced with nβ5, respectively, to obtain the plane orientation coefficient (fn ₅ ) when the two directions on the film surface are α5 and β5. Hereinafter, the same measurement is repeated until the two directions on the film surface become α85 and β85. The average value of the obtained measured values for 18 times from _{fn 0} to fn _{85 is the plane orientation coefficient (fn).}

When the plane orientation coefficient is less than 0.0080, that is, the film is in a state close to or close to non-orientation, the flexibility is sufficient, but the heat resistance may be inferior. On the other hand, if the plane orientation coefficient exceeds 0.0800, the heat resistance may be excellent, but the flexibility may be insufficient. From the viewpoint of achieving both flexibility and heat resistance of the film, the film of the present invention preferably has a plane orientation coefficient of at least one side of 0.0200 or more and 0.0600 or less, preferably 0.0250 or more and 0.0400 or less. Is more preferable.

The method of setting the plane orientation coefficient of at least one side of the film of the present invention to 0.0080 or more and 0.0800 or less or the above-mentioned preferable range is not particularly limited as long as the effect of the present invention is not impaired. Examples thereof include a method in which the film has a B layer and is slightly stretched at a magnification of 1.05 times or more and 1.50 times or less in at least one axial direction. By stretching at such a low magnification, which is not normally used, the molecules of the resin constituting the B layer can be oriented within a range that does not impair the flexibility of the film, and expansion during heating can be reduced. It becomes. Further, within the range of the above stretching conditions, for the molecules having a low glass transition temperature used in the A layer, the equilibrium between the orientation formation and the heat relaxation during stretching is biased to the latter, so that excessive orientation formation can be suppressed and the film can be suppressed. It is possible to reduce the decrease in flexibility. From the above viewpoint, when stretching in two or more directions, the area stretching ratio multiplied by the stretching ratio in each direction is preferably 1.08 times or more and 1.40 times or less, and 1.10 times or more 1 .30 times or less is more preferable.

From the viewpoint of improving heat resistance and reducing chip damage in the semiconductor manufacturing process, the film of the present invention preferably has a maximum stress at 5% elongation at 25 ° C. of 1 MPa or more and 20 MPa or less. If the stress at 5% elongation at 25 ° C. is less than 1 MPa, the film may be deformed during heating depending on the quality of the semiconductor wafer, and if it is larger than 20 MPa, the load when picking up the chip is large and the chip is damaged. It may end up. From the above viewpoint, the stress at 5% elongation at 25 ° C. is more preferably 1.5 MPa or more and 15 MPa or less, and further preferably 2 MPa or more and 10 MPa or less. The method in which the stress at 5% elongation at 25 ° C. is within the above range is not particularly limited, and examples thereof include a method in which the thickness ratio of the B layer to the A layer is 0.25 or less.

"5% stretch stress at 25 ° C" means 5% stretch stress at 25 ° C measured according to JIS K 7127 (1999, test piece type 2). Further, "the stress at 5% elongation at 25 ° C. is 1 MPa or more and 20 MPa or less at the maximum" means that any direction parallel to the film surface is clockwise in the 0 ° direction and 0 ° direction in parallel with the film surface. In the range from 0 ° to 90 °, when the direction rotated by 90 ° is 90 °, 5 at 25 ° C according to JIS K 7127 (1999, test piece type 2) at 5 ° intervals. % It means that the maximum value of the measured values for 19 times obtained by measuring the stress during stretching is 1 MPa or more and 20 MPa or less.

In the film of the present invention, the dimensional change rate at 90 ° C. when the temperature is raised from 25 ° C. to 160 ° C. at a heating rate of 10 ° C./min is 90 ° C. dimensional change rate, and the direction in which the 90 ° C. dimensional change rate is maximum is X. When the 90 ° C. dimensional change rate in the direction and the X direction is Tx (%), Tx is preferably −10% or more and 1% or less. By setting Tx in the above range, it is possible to reduce the deformation when the semiconductor wafers are heated in a laminated state. If Tx is less than -10%, wrinkles may occur due to film shrinkage, and if Tx is larger than 1%, the fixing position of the semiconductor wafer fluctuates due to film expansion, which causes problems in the subsequent process. May occur. From the above viewpoint, Tx is more preferably −8% or more and 0% or less, and further preferably −6% or more and -1% or less.

"90 ° C. Dimensional change rate" means a film of 15 mm (measurement direction) x 4 mm (direction orthogonal to the measurement direction), which has been allowed to stand at a temperature of 25 ° C. and a relative humidity of 65% for 24 hours, from 25 ° C. to 160 ° C. The rate of dimensional change measured at a heating rate of 10 ° C./min and ^{a weight of 120 g / mm 2 at 90 ° C.} The device used for measuring the dimensional change rate at 90 ° C. is not particularly limited as long as the effect of the present invention is not impaired, and for example, TMA / SS6000 (manufactured by Seiko Instruments) or the like can be used. In the X direction, the dimensional change rate of 90 ° C in any direction parallel to the film surface is measured, and then rotated clockwise by 5 ° in parallel with the film surface to reach an angle of 90 ° with the originally selected direction. When the 90 ° C. dimensional change rate is measured in the same manner, the value of the 90 ° C. dimensional change rate is set to the largest value. Then, the value of the dimensional change rate at 90 ° C. at that time is defined as Tx (%).

In the film of the present invention, from the viewpoint of improving heat resistance and reducing deformation due to the weight of the semiconductor wafer, the X direction and the direction orthogonal to the film plane are the Y direction, and the 90 ° C. dimensional change rate in the Y direction is Ty ( %), It is preferable that Tx and Ty satisfy the following formula 1.
Equation 1: 0.1 ≤ | Tx-Ty | ≤ 3.0
| Tx-Ty | means a variation in the in-plane dimensional change rate at 90 ° C. depending on the direction, and when this is 0.1 or more and 3.0 or less, the flatness of the film during heating can be further improved. it can. That is, by making the deformation non-uniform within the film surface within a non-excessive range, the effect of maintaining the flatness of the film due to the dimensional change is likely to appear. When | Tx-Ty | is larger than 3.0, the deformation of the film during heating becomes excessively non-uniform depending on the direction, so that wrinkles and slacks may easily occur. Further, when | Tx-Ty | is smaller than 0.1 and the deformation in the plane does not depend on the direction, the tension may decrease near the center of the fixed sample, and the deformation may occur due to the weight of the semiconductor wafer. There is. From the above viewpoint, | Tx-Ty | is more preferably 0.5 or more and 2.5 or less, and further preferably 0.8 or more and 2.2 or less. Examples of the method of setting | Tx-Ty | in the above range include a method of biaxially stretching the coextruded film having the above-mentioned layer structure. More specifically, the value of | Tx-Ty | can be reduced by reducing the difference in stretching ratio in each direction when stretching in two axes.

In the film of the present invention, the B layer, the A layer, and the B layer are preferably located in this order from the viewpoint of reducing the occurrence of scratches and the like (hereinafter, referred to as a B / A / B configuration). By locating the B layer having a high glass transition temperature on both sides of the A layer having a low glass transition temperature, it is possible to suppress scratches and dents during roll transport and single-wafer handling. The fact that the B layer, the A layer, and the B layer are located in this order means that the B layer, the A layer, and the B layer, the A layer, regardless of whether or not there is another layer outside each B layer or between the A layer and the B layer. And B layer are located in this order. As a specific example of such an embodiment, in addition to the B / A / B configuration consisting of only two B layers and one A layer, neither the A layer nor the B layer is applicable between the B layer and the A layer. B / C / A / B configuration or B / C / A / C / B configuration in which the layer (hereinafter, may be referred to as C layer) is located, and C / B / A / B in which the C layer is located as the outermost layer. Examples thereof include a configuration, a C / B / A / B / C configuration, a B / A / B / A / B configuration composed of a plurality of B layers and a plurality of A layers, a B / A / B / A configuration, and the like. Above all, from the viewpoint of reducing the occurrence of scratches and the like, the film of the present invention preferably has the B layer located on at least one outermost surface, more preferably located on both outermost surfaces, and B / A /. It is particularly preferable to have a B configuration. The composition of each A layer and each B layer in the embodiment having a plurality of A layers and / or B layers may be the same or different as long as the effects of the present invention are not impaired.

From the viewpoint of handling during production and improvement of stretching accuracy, the film of the present invention preferably has a coefficient of static friction of 0.1 or more and 0.8 or less measured by superimposing different surfaces of the film on each other. Here, the coefficient of static friction refers to the coefficient of static friction measured by arranging two films so that their opposite sides overlap each other and rubbing them according to JIS K 7125 (1999). By setting the coefficient of static friction measured by superimposing different surfaces of the film within the above range, it is possible to improve the handling at the time of manufacturing and improve the stretching accuracy when stretching with a roll. In the film manufacturing process of the present invention, as described above, it is required to appropriately control the draw ratio in a low region. If the coefficient of static friction exceeds 0.8, the draw ratio may be higher than designed or spots may occur, especially when the friction with the roll is excessive. If the coefficient of static friction is less than 0.1, the rolls are likely to be misaligned, which may reduce productivity. From the above viewpoint, the coefficient of static friction measured by superimposing different surfaces of the film is more preferably 0.2 or more and 0.7 or less, and further preferably 0.3 or more and 0.6 or less.

The method for setting the coefficient of static friction within the above-mentioned preferable range is not particularly limited as long as the effect of the present invention is not impaired, but at least one outermost layer contains inorganic particles and / or organic particles having an average particle size of 1 μm or more and 10 μm or less. The method and the like can be mentioned. More specifically, the coefficient of static friction can be lowered by increasing the content of these particles. The average particle size referred to here is a volume average particle size.

Examples of the particles include wet and / or dry silica, colloidal silica, aluminum silicate, titanium oxide, calcium carbonate, calcium phosphate, barium sulfate, alumina, mica, kaolin, clay, and inorganic particles such as hydroxyapatite, styrene, silicone, and acrylic. Organic particles or the like whose constituent components are polymerized acids, methacrylic acid, esters, divinylbenzene and the like can be used. Among them, inorganic particles such as wet and / or dry silica and alumina, and organic particles containing a polymer of styrene, silicone, acrylic acid, methacrylic acid, ester, divinylbenzene and the like as constituents are preferably used. As the particles, two or more types of internal particles, inorganic particles, and organic particles may be used, or two or more types of internal particles, inorganic particles, and organic particles may be combined in combination.

The content of the particles is preferably in the range of 0.01 to 5% by mass with respect to the entire resin composition constituting the outermost surface layer of the film. More preferably, it is 0.03 to 3% by mass. If it is less than 0.01% by mass, it may be difficult to wind the film, and if it exceeds 5% by mass, the glossiness may be lowered due to the coarse protrusions, and the transparency and film forming property may be deteriorated.

The film of the present invention has a melt flow rate MFRa (g / 10 min) of 5 or more and 20 or less at a temperature of + 20 ° C., which is the melting point of the resin which is the main component of the A layer, from the viewpoint of reducing the generation of flow marks and improving the interlayer adhesion. It is preferable that the melt flow rate MFRb (g / 10 minutes) at the melting point + 20 ° C. of the resin which is the main component of the B layer is 10 or more and 20 or less, and the MFR and MFRb satisfy the following formula 2.
Equation 2: 0 ≦ | MFRb-MFRa | ≦ 5
The melt flow rate of the resin can be measured according to ASTM D 1238 (1998) under the conditions of melting point + 20 ° C. and 5.0 kgf.

Since the film of the present invention has layers A and B having significantly different characteristics, problems such as flow marks and laminating peeling may occur when both layers are laminated by a co-extrusion method or the like. From this point of view, it is necessary to select the resin used for both layers after fully considering its viscosity characteristics. As a result of diligent studies by the present inventors, the melt flow rates (MFRa, MFRb) of the resin which is the main component of both layers are set to the above-mentioned specific range, and | MFRb-MFRa | is set to 0 or more and 5 or less. It has been found that the occurrence of flow marks is reduced and the interlayer adhesion is improved. From the above viewpoint, MFRa is more preferably 7 or more and 18 or less, and further preferably 9 or more and 15 or less. The MFRb is more preferably 12 or more and 18 or less, and further preferably 13 or more and 16 or less. Further, | MFRb-MFRa | is more preferably 0 or more and 3 or less, and further preferably 0 or more and 1 or less.

Next, the method for producing the film of the present invention will be described. The method for producing a film of the present invention is characterized by having a step of stretching in at least one direction at a magnification of 1.04 times or more and 1.50 times or less. With such an aspect, the dimensional stability at the time of heating is improved. From the above viewpoint, it is preferable to have a step of stretching in at least one direction at a magnification of 1.08 times or more and 1.40 times or less, and a step of stretching in at least one direction at a magnification of 1.10 times or more and 1.30 times or less. It is more preferable to have. Further, in the method for producing a film of the present invention, the film may be biaxially stretched as long as the effect of the present invention is not impaired.

Hereinafter, specific examples of the method for producing a film of the present invention will be described, but the present invention is not construed as being limited to such examples.

The polyester A used for the A layer and the polyester B used for the B layer are supplied to separate vent type twin-screw extruders and melt-extruded. At this time, it is preferable that the oxygen concentration is 0.7% by volume or less and the resin temperature is controlled to + 20 to 30 ° C., which is higher than the melting point of the resin, in the flow nitrogen atmosphere in the extruder. When a plurality of different resins are added to each layer, it is preferable to control the resin temperature based on the value of the resin having the highest melting point. Next, foreign matter is removed and the extrusion amount is proportionalized through a filter and a gear pump, and the T-die discharges the foreign matter onto the cooling drum in the form of a sheet. At that time, the electrostatic application method in which the cooling drum and the resin are brought into close contact with each other by static electricity using an electrode to which a high voltage is applied, the casting method in which a water film is provided between the casting drum and the extruded polymer sheet, and the casting drum temperature of polyester resin The sheet-like polymer is brought into close contact with the casting drum, cooled and solidified, and cast film by a method of adhering the extruded polymer at a glass transition temperature ~ (glass transition point -20 ° C) or a method of combining a plurality of these methods. To get. Among these casting methods, when polyester is used, the electrostatic application method is preferably used from the viewpoint of productivity and flatness.

In the method for producing a film of the present invention, the film is stretched in at least one axial direction at a magnification of 1.05 times or more and 1.50 times or less for the purpose of imparting dimensional stability during heating. The draw ratio in the case of stretching in the uniaxial direction is preferably 1.08 times or more and 1.40 times or less, and more preferably 1.10 times or more and 1.30 times or less. Further, when the film is stretched in the biaxial direction, it is preferable that the area magnification is in the above range. Further, the stretching speed is preferably 1,000% / min or more and 200,000% / min or less. Stretching can be performed at any temperature of room temperature or higher, but it is preferably 20 ° C. or higher and 130 ° C. or lower, and it is preferable to preheat for 1 second or longer before stretching. Further, the stretching method is a sequential biaxial stretching method in which the casting film is stretched in the longitudinal direction and then stretched in the width direction, or stretched in the width direction and then stretched in the longitudinal direction, or the film is stretched in the longitudinal direction and the width direction. It can be carried out by a simultaneous biaxial stretching method in which the film is stretched substantially at the same time, a uniaxial stretching method in which the film is stretched only in the longitudinal direction or the width direction, and the like. Here, the longitudinal direction refers to the traveling direction of the film, and the width direction refers to a direction parallel to the film surface and orthogonal to the longitudinal direction.

Further, the film may be heat-treated after stretching. The heat treatment can be performed by any conventionally known method such as in an oven or on a heated roll. This heat treatment is preferably performed at a temperature of 90 ° C. or higher and lower than the melting point of the polyester of the B layer, and more preferably 120 ° C. or higher and the melting point of the polyester of the B layer of the B layer or lower. Here, the preferable heat treatment temperature indicates the temperature at which the temperature becomes the highest among the heat treatment temperatures performed after stretching. The heat treatment time can be arbitrary as long as the characteristics are not deteriorated, and is preferably 5 seconds or more and 60 seconds or less, more preferably 10 seconds or more and 40 seconds or less, and further preferably 15 seconds or more and 30 seconds or less.

The heat-fixed film is discharged out of the oven, cooled and then wound up as an intermediate product roll. Further, the film can be unwound from the intermediate product roll and cut in parallel with the longitudinal direction so as to have a desired width to obtain a wound final product roll. The final product roll obtained from one intermediate product roll may be one or a plurality of rolls.

The film of the present invention is composed of a layer having a specific glass transition temperature, and the orientation state of the molecules constituting the film is controlled. Therefore, the film of the present invention has both flexibility and heat resistance, and can be suitably used as a base material for a semiconductor manufacturing process or the like.

(1) Using the glass transition temperature differential calorimetry (DSC) of each layer, hold at −120 ° C. for 5 minutes in a nitrogen atmosphere according to JIS-K-7121 (2012), and then reach 250 ° C. at a rate of 20 ° C./min. The temperature of the measurement sample was raised, and it was calculated by the following formula 4 from the measurement results.
Equation 4: Glass transition temperature = (extrapolation glass transition start temperature + extrapolation glass transition end temperature) / 2
Equipment: "Robot DSC-RDC220" manufactured by Seiko Electronics Co., Ltd.
Data analysis system: "Disk session SSC / 5200"
Sample mass: 5 mg
When a plurality of glass transition temperatures were confirmed in each layer, the value obtained by the following method was adopted as the glass transition temperature of that layer. First, the glass transition temperature of the film was measured by the above method, and the obtained measured values were Tg1, Tg2 ... Tgn in ascending order of temperature. Next, according to JIS-K7244 (1999), the tan δ for each temperature of the film was obtained using the dynamic viscoelasticity measuring device “DMS6100” manufactured by Seiko Instruments, Inc., and the temperatures giving the maximum values were determined in ascending order of Tg1, Tg2 ... Corresponding to Tgn. When the values corresponding to each layer were separated from Tg1, Tg2 ... Tgn, the temperature having the largest value of tan δ was adopted as the glass transition temperature of the layer. The measurement conditions for the dynamic viscoelasticity measurement were a tension mode, a drive frequency of 1 Hz, a distance between chucks of 5 mm, and a heating rate of 2 ° C./min.

(2) Planar Orientation Coefficient The refractive index in each direction of the film was measured using an Abbe refractive index meter 4T manufactured by Atago Co., Ltd. equipped with a polarizer, and the plane orientation coefficient was calculated by the following equation. A halogen lamp was used as the light source, a prism having a refractive index of 1.740 was used, and methylene iodide (refractive index 1.740) was used as the immersion liquid. Further, the measurement was carried out on both sides of the film in the environment of 23 ° C. and 65 RH% for 24 hours using a sample whose temperature and humidity were controlled. In the measurement, first, the arbitrary direction parallel to the film plane is α, the direction orthogonal to this in the film plane is β, α and the direction orthogonal to β (thickness direction) is γ, and the refractive index (nα) in each direction is defined as γ. , Nβ, nγ) was measured with an Abbe refractive index meter. _{Using each of the obtained values, the plane orientation coefficient (fn 0} ) was obtained when the two directions on the film surface were α and β by the following equation 3.
Equation 3: fn ₀ = (nα + nβ) / 2-nγ
Next, γ is fixed and α and β are rotated clockwise by 5 ° while maintaining parallelism with the film surface to obtain nα5 and nβ5, and the refractive index (nα5, nβ5, nγ) in each direction is Abbe. It was measured with a refractive index meter, and nα in the above formula 3 was replaced with nα5 and nβ was replaced with nβ5, respectively, and the plane orientation coefficient (fn ₅ ) when the two directions on the film surface were α5 and β5 was obtained. Hereinafter, the same measurement was repeated until the two directions on the film surface became α85 and β85. The average value of the obtained measured values for 18 times from _{fn 0} to fn _{85 was defined as the plane orientation coefficient (fn).}

(3) Stress during 5% elongation at 25 ° C. According to JIS K 7127 (1999, test piece type 2), using a film strength elongation measuring device (AMF / RTA-100) manufactured by Orientec Co., Ltd. It was measured at 25 ° C. and 65% RH. First, a sample cut into a size of 150 mm in length and 10 mm in width in an arbitrary direction was stretched at an original length of 50 mm and a tensile speed of 300 mm / min to obtain a stress at 5% stretching (unit: MPa). .. The same measurement was performed 5 times for each sample, and the average value was calculated. Further, the measurement was carried out in the same manner by changing the direction clockwise by 5 °, and the maximum value of the value in each direction from 0 ° to 85 ° was taken as the stress at 5% elongation at 25 ° C.

(4) Dimensional change rate Tx, Ty
A 15 mm (measurement direction) x 4 mm (direction orthogonal to the measurement direction) film, which was allowed to stand at a temperature of 25 ° C. and a relative humidity of 65% for 24 hours, was heated using TMA / SS6000 (manufactured by Seiko Instruments). The temperature was raised from 25 ° C. to 160 ° C. at a speed of 10 ° C./min, and the dimensional change rate at 90 ° C. was determined. The weight at the time of measurement was 120 g / mm ² .

The measurement direction was arbitrarily selected, measurement was performed 5 times in the selected measurement direction, and the average value of the obtained measured values was taken as the dimensional change rate (%) in that direction. Further, the measurement direction was rotated clockwise by 5 °, and similarly, the value of the dimensional change rate (%) in each direction until the rotation angle reached 90 ° was obtained. The maximum value obtained was defined as Tx (%), and the direction in which Tx (%) was obtained was defined as the X direction. Further, the direction orthogonal to the X direction in the plane was defined as the Y direction, the dimensional change rate in the Y direction was measured in the same manner, and the obtained value was defined as Ty (%).

(5) Specification of layer structure A layer, B layer, and other layers were specified from the glass transition temperature of each film layer measured in (1).

(6) Static friction coefficient Using Toray's slip tester 200G-15C (manufactured by MAKINO SEISAKUSHO), two films are brought into contact with one side and the other side according to JIS K 7125 (1999). The value when rubbed was measured three times, and the average value was taken as the coefficient of static friction.

(7) Melt flow rate (MFR)
First, using a differential scanning calorimeter (RDC220, manufactured by Seiko Electronics Co., Ltd.), a 5 mg resin chip sample was heated from 25 ° C. to 300 ° C. at 20 ° C./min, and the endothermic peak temperature was measured. The obtained value was taken as the melting point of the resin. Next, the melt flow rate of the resin chip whose melting point was measured was measured according to ASTM D 1238 (1998) under the conditions of melting point + 20 ° C. and 5.0 kgf (unit: g / 10 minutes).

(8) Flexibility Draw nine straight lines at intervals of 30 mm parallel to one set of sides on a square film of 300 mm x 300 mm cut out arbitrarily, and then draw nine straight lines at intervals of 30 mm parallel to another set of sides. A straight line was drawn and used as a measurement sample. Using the simultaneous biaxial stretching device, the obtained measurement sample is stretched in the direction parallel to one set of sides and in the direction parallel to the other set of sides under the following conditions, and the distance between the straight lines is based on the following criteria. evaluated. The distance between the straight lines was measured from 6 distances (12 distances in total in 2 directions) formed by 7 straight lines excluding the 2 straight lines at both ends in each direction, and was the farthest from 36 mm. The value was adopted as the measured value. Flexibility was A or higher.
<Stretching conditions>
・ Stretching device: KARO IV lab stretcher made by BRUCKNER ・ Stretching temperature: 25 ℃
-Stretching speed: 10 mm / min-Stretching magnification: 1.20 times <Evaluation criteria>
S: The distance between the straight lines in the stretched film was 36 ± 1 mm.
A: It did not correspond to S, and the distance between straight lines in the stretched film was 36 ± 3 mm.
B: Not applicable to S and A, and the distance between straight lines in the stretched film was 36 ± 6 mm.

(9) Dimensional stability A 200 mm × 200 mm square film cut out arbitrarily was used as a double-sided tape No. 2 manufactured by Nitto Denko Corporation. It was attached to a stainless steel metal frame (outside: 200 mm × 200 mm, inside: 180 mm × 180 mm) at 500 AB to prepare a measurement sample. Next, the measurement sample was allowed to stand on a hot plate heated to 90 ° C. so that the film attached to the metal frame was in contact with the heated surface, and the state of the film when left for 240 minutes was visually observed and obtained. Based on the results, the evaluation was made according to the following criteria. For dimensional stability, S, A1 and A2 were accepted.
S: Neither contraction nor expansion was observed, and the flatness was maintained.
A1: Slight contraction was observed, but the flatness was maintained.
A2: Slight expansion was observed, but the flatness was maintained.
B: Flatness was lost due to contraction or expansion.

(resin)
The resins used in the production of the film are as follows.
(Polyester A)
Polymerization was carried out from terephthalic acid and ethylene glycol using antimony trioxide as a catalyst by a conventional method to obtain polyester A (MFR: 15 g / 10 minutes) having an intrinsic viscosity of 0.65.
(Polyester B)
Polyethylene terephthalate particle master (MFR: 15 g / 10 minutes) having an intrinsic viscosity of 0.65 containing aggregated silica particles having a number average particle diameter of 4.5 μm in polyester A at a particle concentration of 10% by mass.
(Polyester C)
Toray DuPont "Hitrel" (registered trademark) 3001 (MFR: 10g / 10 minutes)
(Polyester D)
Toray Industries, Inc. "Trecon" (registered trademark) 1200S (MFR: 18g / 10 minutes)
(Polyester E)
Toray DuPont "Hitrel" (registered trademark) 7247 (MFR: 15g / 10 minutes)
(Polyester F)
Toray DuPont "Hitrel" (registered trademark) 5557 (MFR: 17g / 10 minutes)
(Polyolefin A)
"Novatec" (registered trademark) PP MA3U (MFR: 11g / 10 minutes) manufactured by Japan Polypropylene Corporation
(Polyolefin B)
DuPont Dow "Engage" (registered trademark) EG8200 (MFR: 5g / 10 minutes)
(Example 1)
The raw material for obtaining the A layer adjusted to the composition shown in Table 1 and the raw material for obtaining the B layer were supplied to separate single-screw extruders having an oxygen concentration of 0.2% by volume. The cylinder temperature of the extruder that supplied the raw material for obtaining the A layer was set to 200 ° C, and the cylinder temperature of the extruder that supplied the raw material for obtaining the B layer was set to 270 ° C. It was sent to a T-die via a short tube and a mouthpiece at 270 ° C., and discharged in a sheet form on a cooling drum whose temperature was controlled to 25 ° C. from the T-die. At that time, static electricity was applied using a wire-shaped electrode having a diameter of 0.1 mm, and the film was brought into close contact with the cooling drum to obtain a casting film. Next, the film was stretched with a simultaneous biaxial stretching device at a preheating temperature of 80 ° C. and a stretching temperature of 90 ° C. at a magnification of 1.1 times in both the longitudinal direction and the width direction, and the total thickness was 180 μm, and the B layer / A layer / B layer. A film having a three-layer structure was obtained. The evaluation results of each characteristic are shown in Table 1.

(Examples 2 to 6, 9 to 14, 16, 17)
The total thickness is 180 μm and the film has a three-layer structure of B layer / A layer / B layer in the same manner as in Example 1 except that the film structure, extrusion conditions, and stretching conditions are as shown in Tables 1 to 3. I got a film. The evaluation results of each characteristic are shown in Tables 1 to 3. Minor flow marks were confirmed in the films obtained in Examples 9 and 10.

(Example 7)
A casting film was obtained in the same manner as in Example 1. Next, it was stretched 1.21 times in the width direction at a preheating temperature of 80 ° C. and a stretching temperature of 90 ° C. with a tenter type transverse stretching machine, had a total thickness of 180 μm, and had a three-layer structure of B layer / A layer / B layer. I got a film. The evaluation results of each characteristic are shown in Table 2.

(Example 8)
A film having a total thickness of 180 μm and a three-layer structure of B layer / A layer / B layer was obtained in the same manner as in Example 7 except that the stretching conditions were as shown in Table 2. The evaluation results of each characteristic are shown in Table 2.

(Example 15)
A casting film was obtained in the same manner as in Example 1. Then, after stretching at a preheating temperature of 80 ° C. and a stretching temperature of 90 ° C. at a magnification of 1.1 times in both the longitudinal direction and the width direction with a simultaneous biaxial stretching device, heat treatment was performed for 20 seconds in a zone heated to 150 ° C. A film having a total thickness of 180 μm and having a three-layer structure of B layer / A layer / B layer was obtained. The evaluation results of each characteristic are shown in Table 3.

(Example 18)
A casting film was obtained in the same manner as in Example 1. Next, the film temperature was raised with a heating roll before stretching in the longitudinal direction, the film was stretched 1.1 times in the longitudinal direction at a stretching temperature of 90 ° C., and immediately cooled with a metal roll whose temperature was controlled to 40 ° C. After that, it was stretched 1.1 times in the width direction at a preheating temperature of 80 ° C. and a stretching temperature of 90 ° C. with a tenter type transverse stretching machine, had a total thickness of 180 μm, and had a three-layer structure of B layer / A layer / B layer. I got a film. The evaluation results of each characteristic are shown in Table 3.

(Example 19)
A film having a total thickness of 180 μm and having a three-layer structure of A layer / B layer / A layer was obtained in the same manner as in Example 1 except that the film structure was as shown in Table 4. The evaluation results of each characteristic are shown in Table 4. There were some dents and scratches on the surface of the obtained film.

(Example 20)
A film having a total thickness of 180 μm and having a two-layer structure of A layer / B layer was obtained in the same manner as in Example 1 except that the film structure was as shown in Table 4. The evaluation results of each characteristic are shown in Table 4. There were some dents and scratches on the surface of the obtained film.

(Comparative Example 1)
A single-layer film having a total thickness of 180 μm and consisting of only the A layer was obtained in the same manner as in Example 1 except that the film composition and extrusion conditions were as shown in Table 5. The evaluation results of each characteristic are shown in Table 5.

(Comparative Examples 2 to 6)
A film having a total thickness of 180 μm and a three-layer structure of B layer / A layer / B layer was obtained in the same manner as in Example 1 except that the film structure, extrusion conditions, and stretching conditions were as shown in Table 5. Obtained. The evaluation results of each characteristic are shown in Table 5. The stretching method "-" in Comparative Example 4 means that the stretching itself was not performed.

The resin composition in the film composition was calculated with the total of the resin components constituting each layer as 100% by mass. When the stretching method is simultaneous biaxial, the stretching ratio is the area magnification, and the stretching ratios in the width direction and the longitudinal direction are the same. The D surface is the surface that was in contact with the cast drum when the film was formed, and the ND surface is the surface opposite to the D surface. The same applies to Tables 2 to 5 as described above.

The stretching direction in Examples 7 and 8 is the width direction.

When the stretching method is sequentially biaxial, the stretching ratio is the area magnification, and the stretching ratios in the width direction and the longitudinal direction are the same.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a film having both flexibility and heat resistance and a method for producing the same, and the film of the present invention can be suitably used as a base material for a semiconductor manufacturing process.

Claims (9)

The main component is a polyester elastomer, and the layer having a glass transition temperature of -100 ° C or higher and 0 ° C or lower is mainly composed of one resin selected from the group consisting of layer A, polyethylene terephthalate, polybutylene terephthalate, and polyester elastomer, and glass. when the transition temperature is a layer with layer B is less than 100 ° C. exceed 0 ° C., an a layer and B layer, and Ri der least one surface of the plane orientation coefficient is 0.0080 or more 0.0800 or less, 5% elongation at stress at 25 ° C., wherein the der Rukoto least 20MPa or less 1MPa at a maximum, the film. The layer containing an olefin elastomer as a main component and having a glass transition temperature of -100 ° C or higher and 0 ° C or lower was designated as a layer A, and the layer containing polypropylene as a main component and having a glass transition temperature of more than 0 ° C and 100 ° C or lower was designated as layer B. Occasionally, it has A layer and B layer, at least one surface orientation coefficient is 0.0080 or more and 0.0800 or less, and the stress at 5% elongation at 25 ° C. is 1 MPa or more and 20 MPa or less at the maximum. A film that features. The dimensional change rate at 90 ° C. when the temperature is raised from 25 ° C. to 160 ° C. at a heating rate of 10 ° C./min is 90 ° C. dimensional change rate, and the direction in which the 90 ° C. dimensional change rate is maximum is 90 in the X direction and the X direction. The film according to claim 1 or 2, wherein the Tx is −10% or more and 1% or less when the dimensional change rate at ° C. is Tx (%). Claimed that Tx and Ty satisfy the following equation 1 when the direction orthogonal to the X direction in the film plane is the Y direction and the 90 ° C. dimensional change rate in the Y direction is Ty (%). Item 3. The film according to item 3.
Equation 1: 0.1 ≤ | Tx-Ty | ≤ 3.0 The film according to any one of claims 1 to 4, wherein the B layer, the A layer, and the B layer are located in this order. The film according to any one of claims 1 to 5, wherein the B layer is located on at least one outermost surface. The film according to any one of claims 1 to 6, wherein the coefficient of static friction measured by superimposing different surfaces of the film is 0.1 or more and 0.8 or less. The melt flow rate MFRa (g / 10 minutes) under the conditions of the melting point of the resin which is the main component of the A layer + 20 ° C. and the load of 5.0 kgf is 5 or more and 20 or less, and is the main component of the B layer. The melt flow rate MFRb (g / 10 minutes) under the conditions of the melting point of the resin at a temperature of + 20 ° C. and a load of 5.0 kgf is 10 or more and 25 or less, and MFRa and MFRb satisfy the following formula 2. The film according to any one of claims 1 to 7.
Equation 2: 0 ≦ | MFRb-MFRa | ≦ 5 The method for producing a film according to any one of claims 1 to 8, further comprising a step of stretching in at least one direction at a magnification of 1.04 times or more and 1.50 times or less.