JP5965070B2 - Stress relaxation film and surface protection film for semiconductor - Google Patents

Description

  The present invention relates to a stress relaxation film, a laminate, a surface protective film for a semiconductor, a method for manufacturing a semiconductor device, and a resin modifier.

  Surface protective films are attached to the surfaces of various resin products such as building materials and optical parts, metal products, and glass products to prevent scratches and dirt from being attached during transportation, storage, and processing. The The surface protective film is also applied, for example, as a protective member for a circuit forming surface during grinding of a semiconductor substrate (see, for example, Japanese Patent No. 3594581 and Japanese Patent Application Laid-Open No. 2010-92945).

By the way, the surface protective film is required to have various properties in addition to the properties usually required for the film such as flexibility and mechanical properties, depending on the object to be protected, the purpose of protection, the use environment, and the like.
For example, a film used for protecting an object from scratches or breakage due to an external force is required to have stress relaxation properties.

Generally, a hard resin is used as a material in order to form a film having stress relaxation properties.
However, a film formed of only a hard resin has stress relaxation properties, but tends to have a low impact strength and is inferior in impact resistance.
The inventors have found that a specific thermoplastic resin containing a large amount of 4-methyl-1-pentene in the skeleton contributes to the improvement of the stress relaxation property of the film in the course of studying the material of the film.
However, according to the specific thermoplastic resin containing a large amount of 4-methyl-1-pentene in the skeleton, the stress relaxation property of the film can be enhanced, but the release property of the film tends to be enhanced. For this reason, the present inventors have also found that delamination tends to occur when laminated with other layers.

Therefore, the first aspect of the present invention is a stress relaxation film having excellent stress relaxation properties and impact resistance, a laminate using the stress relaxation film, a surface protection film for semiconductors, and semiconductor manufacturing. It is an object to provide a method for manufacturing a device.
The second aspect of the present invention is a stress relaxation film having a certain degree of high stress relaxation property and hardly causing delamination when laminated with other layers, and a laminate using the stress relaxation film. It is an object to provide a method for manufacturing a body, a surface protection film for a semiconductor, and a semiconductor manufacturing apparatus.
In addition, the second aspect of the present invention provides a resin modifier that imparts, to a resin, a somewhat high stress relaxation property and adhesion that is difficult to delaminate when laminated with other layers. This is the issue.

  Specific means for solving the above-described problems are as follows.

<1> 70 mol% to 90 mol% of structural units derived from 4-methyl-1-pentene, and 10 mol% to 30 mol% of structural units derived from an α-olefin having 2 or 3 carbon atoms, and , Thermoplastic resin A which is a copolymer having a constitutional unit derived from an α-olefin having 4 to 20 carbon atoms other than 4-methyl-1-pentene and having an amount of 10 mol% or less, an ethylene polymer, and a propylene polymer A thermoplastic resin B other than the thermoplastic resin A, which is at least one polymer selected from the group consisting of a polymer, a butene polymer, and a 4-methyl-1-pentene polymer. The stress that the content of the thermoplastic resin A is 50% by mass to 98% by mass with respect to the total mass, and the content of the thermoplastic resin B is 2% by mass to 50% by mass with respect to the total mass. stress relaxation consisting of relaxation film And thermoplastic resin C which is at least one polymer selected from the group consisting of ethylene-based polymers, propylene-based polymers, and butene-based polymers, and at least a portion is in contact with the stress relaxation layer And a surface layer .

<2> The thermoplastic resin A is a copolymer containing a structural unit derived from 4-methyl-1-pentene 75 mol% to 88 mol%, the laminated body according to <1>.
<3> The laminate according to <1> or <2>, wherein the thermoplastic resin B is at least one polymer selected from the group consisting of an ethylene polymer and a propylene polymer.
<4> The stress relaxation film has a sea-island structure composed of a sea part including the thermoplastic resin A and an island part substantially made of the thermoplastic resin B. <1> to <3> The stress relaxation film as described in any one of 3> .

<5 > 70 mol% to 90 mol% of structural units derived from 4-methyl-1-pentene, and 10 mol% to 30 mol% of structural units derived from an α-olefin having 2 or 3 carbon atoms, and , Thermoplastic resin A which is a copolymer having a constitutional unit derived from an α-olefin having 4 to 20 carbon atoms other than 4-methyl-1-pentene and having an amount of 10 mol% or less, an ethylene polymer, and a propylene polymer A thermoplastic resin B other than the thermoplastic resin A, which is at least one polymer selected from the group consisting of a polymer, a butene polymer, and a 4-methyl-1-pentene polymer. The stress that the content of the thermoplastic resin A is 50% by mass to 98% by mass with respect to the total mass, and the content of the thermoplastic resin B is 2% by mass to 50% by mass with respect to the total mass. Relaxing film and frequency 1.6 storage modulus G at 25 ° C. as measured by z '(25) is, 5 × 10 including 7 and the substrate layer is ^Pa or more, and protect the circuit forming surface of the semiconductor substrate during the grinding of a semiconductor substrate A surface protective film for semiconductors .
<6 > The surface protective film for a semiconductor according to < 5 >, comprising an adhesive layer on the side opposite to the side on which the base material layer of the stress relaxation film is present .

<7 > 70 mol% to 90 mol% of structural units derived from 4-methyl-1-pentene, and 10 mol% to 30 mol% of structural units derived from an α-olefin having 2 or 3 carbon atoms, and , Thermoplastic resin A which is a copolymer having a constitutional unit derived from an α-olefin having 4 to 20 carbon atoms other than 4-methyl-1-pentene and having an amount of 10 mol% or less, an ethylene polymer, and a propylene polymer A thermoplastic resin B other than the thermoplastic resin A, which is at least one polymer selected from the group consisting of a polymer, a butene polymer, and a 4-methyl-1-pentene polymer. The content of the thermoplastic resin A is 2% by mass or more and less than 50% by mass with respect to the total mass, and the content of the thermoplastic resin B is 50% by mass or more and 98% by mass or less with respect to the total mass. , from the stress relaxation film And a thermoplastic resin C which is at least one polymer selected from the group consisting of an ethylene polymer, a propylene polymer, and a butene polymer, and at least a part of the stress relaxation layer. A laminate comprising a surface layer in contact with the relaxation layer .

<8> The thermoplastic resin A is a copolymer containing 70 mol% to 88 mol% of structural units derived from 4-methyl-1-pentene, laminate according to <7>.

< 9 > The laminate according to < 7 > or < 8 >, wherein the thermoplastic resin B is at least one polymer selected from the group consisting of an ethylene polymer and a propylene polymer.
< 10 > The stress relaxation film has a sea-island structure composed of an island part containing the thermoplastic resin A and a sea part substantially made of the thermoplastic resin B. < 7 > to < The laminate according to any one of 9 > .

<11 > 70 mol% to 90 mol% of structural units derived from 4-methyl-1-pentene, and 10 mol% to 30 mol% of structural units derived from an α-olefin having 2 or 3 carbon atoms, and , Thermoplastic resin A which is a copolymer having a constitutional unit derived from an α-olefin having 4 to 20 carbon atoms other than 4-methyl-1-pentene and having an amount of 10 mol% or less, an ethylene polymer, and a propylene polymer A thermoplastic resin B other than the thermoplastic resin A, which is at least one polymer selected from the group consisting of a polymer, a butene polymer, and a 4-methyl-1-pentene polymer. The content of the thermoplastic resin A is 2% by mass or more and less than 50% by mass with respect to the total mass, and the content of the thermoplastic resin B is 50% by mass or more and 98% by mass or less with respect to the total mass. , With stress relaxation film Storage modulus G at 25 ° C. as measured at a frequency 1.6 Hz '(25) comprises a substrate layer is 5 × 10 7 ^Pa or more, the circuit formation of the semiconductor substrate during the grinding of a semiconductor substrate Surface protective film for semiconductors that protects the surface .
<12 > The surface protective film for a semiconductor according to < 11 >, comprising an adhesive layer on the side opposite to the side on which the base material layer of the stress relaxation film is present .

In this specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
In this specification, when referring to the amount of each component in the composition, when there are a plurality of substances corresponding to each component in the composition, a plurality of substances present in the composition unless otherwise specified. Means the total amount.
In this specification, “(meth) acrylate” represents at least one selected from acrylate and methacrylate.
In this specification, the term “process” is not limited to an independent process, but is included in the term if the intended purpose of the process is achieved even if it cannot be clearly distinguished from other processes. It is.

According to the first aspect of the present invention, a stress relaxation film having excellent stress relaxation properties and impact resistance, a laminate using the stress relaxation film, a surface protection film for semiconductors, and semiconductor manufacturing An apparatus manufacturing method can be provided.
According to the second aspect of the present invention, the stress relaxation film having a somewhat high stress relaxation property and hardly causing delamination when laminated with another layer, and the stress relaxation film are used. , A laminate, a surface protection film for a semiconductor, and a method for manufacturing a semiconductor manufacturing apparatus can be provided.
Further, according to the second aspect of the present invention, the resin modifier for imparting a certain degree of high stress relaxation to the resin and adhesion that is difficult to delaminate when laminated with other layers is provided. Can be provided.

It is a TEM image of the film of Example 2A. It is a TEM image of the film of Example 3B.

  Hereinafter, specific embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and may be implemented with appropriate modifications within the scope of the object of the present invention. be able to.

<< First Aspect >>
[Stress relaxation film]
The stress relaxation film which concerns on the 1st aspect of this invention is the structure derived from 70 mol%-90 mol%, and the C2-C3 alpha olefin from the structural unit derived from 4-methyl-1- pentene. Heat which is a copolymer containing 10 mol% to 30 mol% of units and having a proportion of structural units derived from an α-olefin having 4 to 20 carbon atoms other than 4-methyl-1-pentene. The thermoplastic resin, which is a plastic resin A and at least one polymer selected from the group consisting of an ethylene polymer, a propylene polymer, a butene polymer, and a 4-methyl-1-pentene polymer. A thermoplastic resin B other than A, and the content of the thermoplastic resin A is 50% by mass to 98% by mass with respect to the total mass, and the content of the thermoplastic resin B is based on the total mass. 2 mass% to 50 mass% The

A film used for protecting an object from scratches or breakage due to an external force is required to have characteristics such as stress relaxation properties. Generally, in order to form a film having stress relaxation properties, a hard resin is used as a material. However, a film formed only of a hard resin tends to have a low impact strength. On the other hand, a film using a flexible resin as a material has high impact strength and impact resistance, but tends to be inferior in stress relaxation properties. And, if a flexible resin is added to a hard resin to form a film, the impact strength of the film can be improved, but the proportion of the hard thermoplastic resin is reduced by adding the flexible thermoplastic resin. The stress relaxation property of the film is lowered.
Therefore, it can be said that having stress relaxation and having shock resistance are in a trade-off relationship that if one is to be realized, the other must be sacrificed.

  In the first aspect of the present invention, the film is made of a specific thermoplastic resin A containing a large amount of 4-methyl-1-pentene in the skeleton, which tends to harden the resin at room temperature (25 ° C.), and a flexible specific film. By making it the aspect which contains the thermoplastic resin B in a specific ratio, the film which combined the outstanding stress relaxation property and impact resistance is implement | achieved.

  Hereinafter, the components contained in the stress relaxation film according to the first aspect of the present invention will be described.

[Thermoplastic resin A]
The thermoplastic resin A in the first aspect of the present invention is a structural unit derived from 70 mol% to 90 mol% of a structural unit derived from 4-methyl-1-pentene and an α-olefin having 2 or 3 carbon atoms. 10% by mole to 30% by mole, and a copolymer having a proportion of structural units derived from an α-olefin having 4 to 20 carbon atoms other than 4-methyl-1-pentene (hereinafter referred to as “ It is also referred to as “4-methyl-1-pentene copolymer”.

The 4-methyl-1-pentene copolymer according to the first aspect of the present invention contains 70 mol% to 90 mol% of a structural unit derived from 4-methyl-1-pentene, and is 75 mol. % To 89 mol% is more preferable, and 80 mol% to 86 mol% is further more preferable.
When the structural unit derived from 4-methyl-1-pentene contained in the 4-methyl-1-pentene copolymer is less than 70 mol%, it is not possible to obtain excellent stress relaxation properties as a protective film. Moreover, when the structural unit derived from 4-methyl-1-pentene contained in the 4-methyl-1-pentene copolymer exceeds 90 mol%, it is impossible to obtain excellent impact resistance as a protective film.

The 4-methyl-1-pentene copolymer according to the first aspect of the present invention contains 10 to 30 mol% of a structural unit derived from an α-olefin having 2 or 3 carbon atoms, It is more preferable that 11 mol%-25 mol% are contained, and it is still more preferable that 14 mol%-20 mol% is contained.
When the structural unit derived from the α-olefin having 2 or 3 carbon atoms contained in the 4-methyl-1-pentene copolymer is less than 10 mol%, the rigidity of the material is excessively increased, so that the impact resistance is lowered. At the same time, appropriate stress relaxation properties cannot be obtained. Moreover, when the structural unit derived from the α-olefin having 2 or 3 carbon atoms contained in the 4-methyl-1-pentene copolymer exceeds 30 mol%, the crystallinity is lowered and the melting point is not observed. Softening advances and film forming becomes difficult.

  The structural unit derived from an α-olefin having 2 or 3 carbon atoms is a structural unit derived from ethylene or propylene. In the present invention, the structural unit derived from the α-olefin having 2 or 3 carbon atoms is derived from propylene in that the glass transition temperature is designed around room temperature to balance the impact resistance and the stress relaxation property. Units are particularly preferred.

The 4-methyl-1-pentene copolymer in the first aspect of the present invention may include a structural unit derived from an α-olefin having 4 to 20 carbon atoms other than 4-methyl-1-pentene. . In the 4-methyl-1-pentene copolymer, the proportion of structural units derived from α-olefins having 4 to 20 carbon atoms other than 4-methyl-1-pentene is 10 mol% or less, preferably 5 mol. % Or less, more preferably 3 mol% or less, and still more preferably 1 mol% or less. In the first aspect of the present invention, the 4-methyl-1-pentene copolymer does not contain a structural unit derived from an α-olefin having 4 to 20 carbon atoms other than 4-methyl-1-pentene. Is particularly preferred.
When the proportion of structural units derived from an α-olefin having 4 to 20 carbon atoms other than 4-methyl-1-pentene in the 4-methyl-1-pentene copolymer exceeds 10 mol%, the material becomes flexible. Progresses and tends to be inferior in stress relaxation properties.

  Examples of the α-olefin having 4 to 20 carbon atoms include linear or branched α-olefins, cyclic olefins, aromatic vinyl compounds, conjugated dienes, non-conjugated polyenes, and functional vinyl compounds.

  Examples of the linear or branched α-olefin that can be a constituent unit of the 4-methyl-1-pentene copolymer include 1-butene, 1-pentene, 1-hexene, 1-octene, and 1-decene. , 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene, etc., a linear α-olefin having 4 to 20 carbon atoms (preferably 4 to 10); 3-methyl-1-butene 3-methyl-1-pentene, 3-ethyl-1-pentene, 4,4-dimethyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4-ethyl-1 Examples include branched α-olefins having 5 to 20 carbon atoms (more preferably 5 to 10 carbon atoms) such as -hexene and 3-ethyl-1-hexene.

  Examples of the cyclic olefin that can be a constituent unit of the 4-methyl-1-pentene copolymer include carbon such as cyclopentene, cycloheptene, norbornene, 5-methyl-2-norbornene, tetracyclododecene, vinylnorbornene, and vinylcyclohexane. The compound of several 4-20 (preferably 5-15) is mentioned.

  Examples of the aromatic vinyl compound that can be a constituent unit of the 4-methyl-1-pentene copolymer include styrene; α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, o, p. -Mono- or polyalkyl styrene such as dimethyl styrene, o-ethyl styrene, m-ethyl styrene, p-ethyl styrene and the like.

  Examples of conjugated dienes that can be structural units of 4-methyl-1-pentene copolymers include 1,3-butadiene, isoprene, chloroprene, 1,3-pentadiene, 2,3-dimethylbutadiene, 4-methyl- Examples thereof include compounds having 4 to 20 carbon atoms (preferably 4 to 10) such as 1,3-pentadiene, 1,3-pentadiene, 1,3-hexadiene, and 1,3-octadiene.

  Examples of the non-conjugated polyene that can be a structural unit of the 4-methyl-1-pentene copolymer include 1,4-pentadiene, 1,4-hexadiene, 1,5-hexadiene, 1,4-octadiene, 1, 5-octadiene, 1,6-octadiene, 1,7-octadiene, 2-methyl-1,5-hexadiene, 6-methyl-1,5-heptadiene, 7-methyl-1,6-octadiene, 4-ethylidene- 8-methyl-1,7-nonadiene, 4,8-dimethyl-1,4,8-decatriene (DMDT), dicyclopentadiene, cyclohexadiene, dicyclooctadiene, methylene norbornene, 5-vinyl norbornene, 5-ethylidene 2-norbornene, 5-methylene-2-norbornene, 5-isopropylidene-2-norbornene, 6- 5 to 5 carbon atoms such as loromethyl-5-isopropylene-2-norbornene, 2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-2,2-norbornadiene There are 20 (preferably 5 to 10) compounds.

  Examples of the functionalized vinyl compound that can be a constituent unit of the 4-methyl-1-pentene copolymer include a hydroxyl group-containing olefin; a halogenated olefin; acrylic acid, propionic acid, 3-butenoic acid, 4-pentenoic acid, 5 Unsaturated carboxylic acids such as hexenoic acid, 6-heptenoic acid, 7-octenoic acid, 8-nonenoic acid and 9-decenoic acid; unsaturated amines such as allylamine, 5-hexenamine and 6-heptenamine; 7-octadienyl) succinic anhydride, pentapropenyl succinic anhydride, unsaturated acid anhydrides such as unsaturated carboxylic acids, halides of unsaturated carboxylic acids, 4-epoxy-1-butene 5-epoxy-1-pentene, 6-epoxy-1-hexene, 7-epoxy-1-heptene, 8-epoxy-1-octene, 9 Epoxy-1-nonene, 10-epoxy-1-decene, and unsaturated epoxy compounds such as 11-epoxy-1-undecene and the like.

The hydroxyl group-containing olefin that can be a constituent unit of the 4-methyl-1-pentene copolymer is not particularly limited as long as it is an olefin compound having a hydroxyl group, and is preferably a terminal hydroxylated olefin compound.
Examples of the terminal hydroxylated olefin compound include vinyl alcohol, allyl alcohol, hydroxyl-1-butene, hydroxyl-1-pentene, hydroxyl-1-hexene, hydroxyl-1-octene, and hydroxyl-1-decene. , Hydroxyl-1-dodecene, hydroxyl-1-tetradecene, hydroxyl-1-hexadecene, hydroxyl-1-octadecene, hydroxyl-1-octadecene, hydroxyl-1-eicosene, etc., having 4 to 20 carbon atoms (preferably 2-10) Linear hydroxylated α-olefin; hydroxylated 3-methyl-1-butene, hydroxylated 4-methyl-1-pentene, hydroxylated 3-methyl-1-pentene, hydroxylated 3-ethyl- 1-pentene, hydroxylated-4,4-dimethyl-1-pentene, hydroxyl-4-methyl-1-hexene, hydroxylated-4,4-dimethyl-1-hexene, hydroxyl-4-ethyl-1- Hexene, hydroxy acid Preferably, such 3-ethyl-1-hexene, and the like branched hydroxide α- olefin having 5 to 20 carbon atoms (more preferably 5 to 10).

  Examples of the halogenated olefin that can be a constituent unit of the 4-methyl-1-pentene copolymer include, for example, halogenated-1-butene, halogenated-1-pentene, halogenated-1-hexene, and halogenated-1- 4 to 20 carbon atoms such as octene, halogenated-1-decene, halogenated-1-dodecene, halogenated-1-tetradecene, halogenated-1-hexadecene, halogenated-1-octadecene, halogenated-1-eicocene (Preferably 4 to 10) linear halogenated α-olefin; halogenated-3-methyl-1-butene, halogenated-4-methyl-1-pentene, halogenated-3-methyl-1-pentene Halogenated-3-ethyl-1-pentene, halogenated-4,4-dimethyl-1-pentene, halogenated-4-methyl-1-hexene 5-5 (more preferably 5-10) carbon atoms such as halogenated-4,4-dimethyl-1-hexene, halogenated-4-ethyl-1-hexene, halogenated-3-ethyl-1-hexene, etc. Examples thereof include branched halogenated α-olefins.

As the structural unit derived from an α-olefin having 4 to 20 carbon atoms other than 4-methyl-1-pentene that can be a structural unit of the 4-methyl-1-pentene copolymer, among them, 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, Particularly preferred is at least one selected from the group consisting of 1-eicosene, vinylcyclohexane, and styrene.
When the 4-methyl-1-pentene copolymer contains a structural unit derived from an α-olefin having 4 to 20 carbon atoms other than 4-methyl-1-pentene, other than 4-methyl-1-pentene Only 1 type of structural unit derived from a C4-C20 alpha olefin may be contained, and 2 or more types may be contained.

  A structural unit derived from 4-methyl-1-pentene, a structural unit derived from an α-olefin having 2 or 3 carbon atoms, contained in the 4-methyl-1-pentene copolymer in the first aspect of the present invention. And the content rate (mol%) of the structural unit derived from C4-C20 alpha-olefins other than 4-methyl-1-pentene can be measured with the following method.

~conditions~
Measuring apparatus: Nuclear magnetic resonance apparatus (ECP500 type, manufactured by JEOL Ltd.)
Observation nucleus: ¹³ C (125 MHz)
Sequence: Single pulse proton decoupling Pulse width: 4.7 μsec (45 ° pulse)
Repeat time: 5.5 seconds Accumulated number: 10,000 times or more Solvent: Orthodichlorobenzene / deuterated benzene (volume ratio: 80/20) mixed solvent Sample concentration: 55 mg / 0.6 mL
Measurement temperature: 120 ° C
Standard value of chemical shift: 27.50ppm

  The 4-methyl-1-pentene copolymer is a structural unit derived from 4-methyl-1-pentene and an α-olefin having 2 or 3 carbon atoms within the range not impairing the effect of the first aspect of the present invention. And a structural unit other than the structural unit derived from the α-olefin having 4 to 20 carbon atoms other than 4-methyl-1-pentene may be included.

The 4-methyl 1-pentene copolymer in the first aspect of the present invention has an intrinsic viscosity [η] measured at 135 ° C. in a decalin solvent of 0.5 dl / g to 5.0 dl / g. It is preferably 0.5 dl / g to 4.0 dl / g. When the intrinsic viscosity [η] of the 4-methyl 1-pentene copolymer is within the above range, the low molecular weight is small and the stickiness of the film is reduced, and the extrusion film can be formed.
The intrinsic viscosity [η] of the 4-methyl 1-pentene copolymer is a value measured by the following method using an Ubbelohde viscometer.
After dissolving about 20 mg of 4-methyl 1-pentene copolymer in 25 ml of decalin, the specific viscosity ηsp is measured in an oil bath at 135 ° C. using an Ubbelohde viscometer. After 5 ml of decalin is added to the decalin solution for dilution, the specific viscosity ηsp is measured in the same manner as described above. This dilution operation is further repeated twice, and the value of ηsp / C when the concentration (C) is extrapolated to 0 is obtained as the intrinsic viscosity [η] (unit: dl / g) (see the following formula 1).
[Η] = lim (ηsp / C) (C → 0) Equation 1

The weight average molecular weight (Mw) of the 4-methyl-1-pentene copolymer in the first aspect of the present invention is preferably 1 × 10 ⁴ to 2 × 10 ⁶ from the viewpoint of film moldability, It is more preferable that it is 1 × 10 ⁴ to 1 × 10 ⁶ .
The molecular weight distribution (Mw / Mn) of the 4-methyl-1-pentene copolymer in the first aspect of the present invention is 1.0 to 3.5 from the viewpoint of film stickiness and appearance. Preferably, it is 1.1-3.0.

  The weight average molecular weight (Mw) of the 4-methyl-1-pentene copolymer and the molecular weight distribution (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) are: It is a value calculated by the standard polystyrene conversion method using the following gel permeation chromatography (GPC).

~conditions~
Measuring device: GPC (ALC / GPC 150-C plus type, suggested refractometer detector integrated type, manufactured by Waters)
Column: 2 GMH6-HT (manufactured by Tosoh Corp.) and 2 GMH6-HTL (manufactured by Tosoh Corp.) connected in series Eluent: o-dichlorobenzene Column temperature: 140 ° C
Flow rate: 1.0 mL / min

The melt flow rate (MFR) of the 4-methyl 1-pentene copolymer in the first aspect of the present invention is 0.1 g / 10 min to 100 g / 10 min from the viewpoint of fluidity during molding. It is preferable that it is 0.5 g / 10 min to 50 g / 10 min, more preferably 0.5 g / 10 min to 30 g / 10 min.
The melt flow rate (MFR) of the 4-methyl 1-pentene copolymer is a value measured according to ASTM D1238. Specifically, the melt flow rate (MFR) of the 4-methyl 1-pentene copolymer is a value measured at 230 ° C. with a load of 2.16 kg.

Density of 4-methyl-1-pentene copolymer of the first aspect of the present invention, from the viewpoint of handling ^properties, is preferably ^{820kg / m 3 ~870kg / m 3} , 830kg / m 3 ~850kg / more preferably m ^3.
The density of the 4-methyl 1-pentene copolymer is a value measured according to JIS K7112 (density gradient tube method).

The melting point (Tm) of the 4-methyl 1-pentene copolymer in the first aspect of the present invention is not observed or preferably 100 ° C. to 180 ° C., not observed, or 110 ° C. to 160 ° C. More preferably, it is ° C.
The melting point (Tm) of the 4-methyl 1-pentene copolymer is a value measured by the following method using a differential scanning calorimeter (DSC).
About 5 mg of 4-methyl 1-pentene copolymer was sealed in an aluminum pan for measurement of a differential scanning calorimeter (DSC220C type) manufactured by Seiko Instruments Inc., and the temperature was changed from room temperature to 200 ° C. at 10 ° C./min. Until heated. In order to completely melt the 4-methyl 1-pentene copolymer, it is held at 200 ° C. for 5 minutes and then cooled to −50 ° C. at 10 ° C./min. After 5 minutes at −50 ° C., the second heating is performed to 200 ° C. at 10 ° C./min, and the peak temperature (° C.) at the second heating is defined as the melting point (Tm) of the copolymer. When a plurality of peaks are detected, the peak detected on the highest temperature side is adopted.

The 4-methyl 1-pentene copolymer in the first aspect of the present invention forms a film having a thickness of 50 μm, and the maximum value of the loss tangent (tan δ) measured 3 days after the film formation is −5 ° C. It is in a temperature range of -50 ° C, preferably 0 ° C-45 ° C, more preferably in a temperature range of 0 ° C-40 ° C, and the maximum value of loss tangent (tan δ) is 0.5 or more. It is preferably 1.0 or more, more preferably 1.2 or more. The 4-methyl 1-pentene copolymer is more excellent in stress relaxation properties when the maximum value of the loss tangent (tan δ) is within the above temperature range and the maximum value is 0.5 or more.
The maximum value of the loss tangent (tan δ) of the 4-methyl 1-pentene-based copolymer and the temperature at which the maximum value is shown are a viscoelasticity measuring device (MCR301, Anton Paar). And a dynamic viscoelasticity in a temperature range of −70 to 180 ° C. is measured at a frequency of 10 rad / s.

  The 4-methyl 1-pentene copolymer in the first aspect of the present invention is a conventionally known synthesis method using a metallocene catalyst, for example, International Publication No. 2005/121192, International Publication No. 2011/055803. It can be synthesized by a method described in a pamphlet or the like.

The content of the thermoplastic resin A in the stress relaxation film according to the first aspect of the present invention is 50% by mass to 98% by mass, and 50% by mass to 96% by mass with respect to the total mass of the stress relaxation film. %, And more preferably 60% by mass to 95% by mass.
When the content of the thermoplastic resin A is less than 50% by mass with respect to the total mass of the stress relaxation film, it is not possible to obtain excellent stress relaxation properties as a protective film.
If the content of the thermoplastic resin A exceeds 98% by mass with respect to the total mass of the stress relaxation film, excellent impact resistance as a protective film cannot be obtained.

[Thermoplastic resin B]
The thermoplastic resin B in the first aspect of the present invention is at least one selected from the group consisting of an ethylene polymer, a propylene polymer, a butene polymer, and a 4-methyl-1-pentene polymer. Polymer (however, excluding the above-mentioned thermoplastic resin A). The thermoplastic resin B in the present invention is preferably at least one polymer selected from the group consisting of ethylene polymers and propylene polymers.

The ethylene polymer may be a homopolymer of ethylene or a copolymer (copolymer) of ethylene and another monomer. Examples of the ethylene polymer include low-density polyethylene, medium-density polyethylene, high-density polyethylene, and high-pressure method low-density polyethylene, which are produced by a conventionally known method. Examples of the ethylene polymer also include an ethylene polymer elastomer.
Moreover, as a preferable ethylene-type polymer in the thermoplastic resin B, the preferable ethylene-type polymer in the below-mentioned thermoplastic resin C is mentioned.

The propylene polymer may be a propylene homopolymer (homopolymer) or a copolymer of propylene and another monomer (copolymer). Examples of the propylene polymer include isotactic propylene polymer and syndiotactic propylene polymer. The isotactic propylene polymer may be a homopropylene polymer, or may be a propylene / α-olefin having 2 to 20 carbon atoms (excluding propylene) random copolymer, A propylene block copolymer may be used. Examples of the propylene polymer include a propylene polymer elastomer.
Moreover, as a preferable propylene-type polymer in the thermoplastic resin B, the preferable propylene-type polymer in the thermoplastic resin C mentioned later is mentioned.

The butene-based polymer may be a butene homopolymer (homopolymer) or a copolymer of butene and another monomer (copolymer). Examples of the butene polymer include a homopolymer of 1-butene, a copolymer of 1-butene and an olefin excluding 1-butene, and the like. Examples of the copolymer include 1-butene / ethylene random copolymer, 1-butene / propylene random copolymer, 1-butene / methylpentene copolymer, 1-butene / methylbutene copolymer, 1-butene Examples include butene / propylene / ethylene copolymer.
Moreover, as a preferable butene polymer in the thermoplastic resin B, a preferable butene polymer in the thermoplastic resin C to be described later can be cited.

  The 4-methyl-1-pentene polymer may be a homopolymer of 4-methyl-1-pentene, or a copolymer of 4-methyl-1-pentene and other monomers. (Copolymer) may be used. Examples of 4-methyl-1-pentene polymers include 4-methyl-1-pentene homopolymer, 4-methyl-1-pentene and 1-hexene, 1-decene, 1-octadecene, 1-hexadecene, and the like. And a random copolymer.

The melt flow rate (MFR) of the thermoplastic resin B in the first aspect of the present invention is preferably from 0.1 g / 10 min to 100 g / 10 min from the viewpoint of film moldability and mechanical properties of the film. More preferably, it is 5g / 10min-50g / 10min.
The melt flow rate (MFR) of the thermoplastic resin B is a value measured in accordance with ASTM D1238. Specifically, the melt flow rate (MFR) of the ethylene polymer and the butene polymer is a value measured at 190 ° C. with a load of 2.16 kg, and the melt flow rate (MFR) of the propylene polymer. ) Is a value measured at 230 ° C. with a load of 2.16 kg, and the melt flow rate (MFR) of the 4-methyl-1-pentene polymer is measured at 260 ° C. with a load of 5.0 kg. Is the value to be

The density of the thermoplastic resin B in the first embodiment of the present invention is 820 kg / m ^{3 to} 960 kg from the viewpoints of lightness and dispersibility when a 4-methyl-1-pentene copolymer and a composition are used. / preferably ^m is ^3, and more preferably ^{830kg / m 3 ~950kg / m 3} .
The density of the thermoplastic resin B is a value measured according to JIS K7112 (density gradient tube method).

Content of the thermoplastic resin B in the stress relaxation film which concerns on the 1st aspect of this invention is 2 mass%-50 mass% with respect to the total mass of a stress relaxation film, and 4 mass%-50 mass. %, Preferably 5% by mass to 40% by mass.
When the content of the thermoplastic resin B is less than 2% by mass with respect to the total mass of the stress relaxation film, excellent impact resistance as a protective film cannot be obtained.
When the content of the thermoplastic resin B exceeds 50% by mass with respect to the total mass of the stress relaxation film, stress relaxation excellent as a protective film cannot be obtained.

[Other resins]
The stress relaxation film according to the first aspect of the present invention contains other resins other than the above-described thermoplastic resin A and thermoplastic resin B within a range not impairing the object of the first aspect of the present invention. It may be.

[Structure of stress relaxation film]
The stress relieving film according to the first aspect of the present invention preferably has a sea-island structure composed of a sea part including the thermoplastic resin A and an island part substantially made of the thermoplastic resin B. .
In the present invention, the island part “consisting essentially of the thermoplastic resin B” means that the content of the thermoplastic resin B in the island part is 70% by mass or more based on the total mass of the constituent components of the island part. Means that.

The stress relaxation film according to the first aspect of the present invention has a sea-island structure composed of a sea part that includes the thermoplastic resin A and an island part that is substantially made of the thermoplastic resin B. As a result, it is possible to combine more excellent stress relaxation properties and impact resistance.
The reason why such an effect is achieved is that the thermoplastic resin A responsible for stress relaxation becomes the sea part, the stress relaxation property is ensured, and the thermoplastic resin B responsible for improvement of impact strength becomes the island part, It is considered that the effect of improving the impact strength of the thermoplastic resin B is more effectively exhibited by dispersing in the film, and the impact resistance of the film is increased.

  In addition, the stress relaxation film according to the first aspect of the present invention has a sea-island structure composed of a sea part that includes the thermoplastic resin A and an island part that is substantially made of the thermoplastic resin B. This can be confirmed by, for example, a transmission electron microscope (TEM). Specifically, the film is ground to produce an ultrathin section, and only one of the components is selectively stained with a heavy metal such as ruthenium tetroxide or osmium tetroxide, and then observed using a transmission electron microscope. To do.

  A film having a sea-island structure composed of a sea part including the thermoplastic resin A and an island part substantially composed of the thermoplastic resin B is, for example, a dry blend of the thermoplastic resin A and the thermoplastic resin B. Obtained by mixing and extrusion to form a film.

[Manufacturing method of stress relaxation film]
An example of the manufacturing method of the stress relaxation film which concerns on the 1st aspect of this invention is demonstrated. The stress relaxation film according to the first aspect of the present invention can be produced, for example, by the following method. However, the first aspect of the present invention is not limited to the following method.
The thermoplastic resin A and the thermoplastic resin B are mixed (for example, dry blended). Subsequently, the obtained mixture is put into a hopper of an extruder provided with a T die, and the cylinder temperature is set to 100 ° C. to 270 ° C. and the die temperature is set to 200 ° C. to 270 ° C. The melt-kneaded material is extruded from a T die and cast to obtain a stress relaxation film.

  The thickness of the stress relaxation film according to the first aspect of the present invention is preferably 50 μm to 350 μm, more preferably 60 μm to 300 μm, and still more preferably 70 μm to 200 μm. When the thickness of the stress relaxation film of the present invention is within the above range, handleability is easy.

[Use of stress relaxation film]
The stress relaxation film according to the first aspect of the present invention is used for the purpose of preventing scratches and preventing dust during transportation, storage, processing, etc. of various resin products such as building materials and optical parts, metal products, and glass products. The protective film can be suitably used as a protective film adhered to these surfaces.

  In addition, the stress relaxation film according to the first aspect of the present invention provides a circuit board surface that is not damaged when the circuit board non-circuit formation surface of the semiconductor substrate is ground to a desired thickness. It can be particularly suitably used as a protective film for preventing breakage. Since the stress relaxation film according to the first aspect of the present invention is excellent in stress relaxation property and impact resistance, it is effective in preventing damage and breakage of the circuit formation surface of the semiconductor substrate.

[Laminate]
The laminate according to the first aspect of the present invention includes a stress relaxation layer comprising the stress relaxation film according to the first aspect of the present invention, an ethylene polymer, a propylene polymer, and a butene polymer. A thermoplastic resin C which is at least one polymer selected from the group consisting of: and a surface layer at least partially in contact with the stress relaxation layer.
The laminate according to the first aspect of the present invention has excellent stress relaxation properties and impact resistance, and delamination does not easily occur between the stress relaxation layer and the surface layer.

(Stress relaxation layer)
The stress relaxation layer in the laminate according to the first aspect of the present invention is composed of the above-described stress relaxation film according to the first aspect of the present invention. Since the laminated body which concerns on the 1st aspect of this invention contains the stress relaxation layer which consists of the stress relaxation film which concerns on the 1st aspect of the above-mentioned this invention, it has the outstanding stress relaxation property and impact resistance. In addition, since it mentioned above about the stress relaxation film concerning the 1st aspect of this invention, description is abbreviate | omitted here.

[Surface layer]
The surface layer in the laminate according to the first aspect of the present invention comprises a thermoplastic resin C which is at least one polymer selected from the group consisting of an ethylene polymer, a propylene polymer, and a butene polymer. And at least a portion is in contact with the stress relaxation layer. In the laminate according to the first aspect of the present invention, the surface layer may be present only on one side of the stress relaxation layer (that is, only one layer) or on both sides of the stress relaxation layer (that is, 2 layers in total) may be present.
The surface layer in the laminate according to the first aspect of the present invention comprises a thermoplastic resin C which is at least one polymer selected from the group consisting of an ethylene polymer, a propylene polymer, and a butene polymer. Therefore, delamination is unlikely to occur between the stress relaxation layer.
In the present invention, “at least a part is in contact with the stress relaxation layer” means that the surface layer is in contact with a part of the stress relaxation layer or the surface layer is in contact with the entire stress relaxation layer. Means that. In the laminate according to the first aspect of the present invention, the contact ratio between the stress relaxation layer and the surface layer is preferably 30% to 100%, and 50% to 100% with respect to the total area of the stress relaxation layer. % Is more preferable.

(Thermoplastic resin C)
The thermoplastic resin C in the first aspect of the present invention is at least one polymer selected from the group consisting of an ethylene polymer, a propylene polymer, and a butene polymer. As the thermoplastic resin C in the first aspect of the present invention, a propylene-based polymer and a butene-based polymer are used in that a surface layer that is less likely to cause delamination between the stress relaxation layer can be formed. It is preferably at least one polymer selected from the group consisting of, and more preferably a propylene-based polymer.
The ethylene-based polymer, the propylene-based polymer, and the butene-based polymer here are synonymous with the ethylene-based polymer, the propylene-based polymer, and the butene-based polymer described in the section of the thermoplastic resin B, respectively. It is.

  As the ethylene-based polymer, a polymer having a proportion of structural units derived from ethylene of 50 mol% or more is preferable. Moreover, as a propylene-type polymer, the polymer whose ratio of the structural unit derived from propylene is 50 mol% or more is preferable. Further, the butene polymer is preferably a polymer in which the proportion of structural units derived from 1-butene is 50 mol% or more.

When the ethylene polymer is a copolymer, the copolymer can form ethylene and a carbon number of 3 to 20 in that it can form a surface layer that is less likely to cause delamination between the stress relaxation layer. It is preferable that it is a copolymer with an α-olefin, more preferably a copolymer of ethylene and an α-olefin having 3 to 10 carbon atoms.
The proportion of structural units derived from ethylene in the ethylene polymer is preferably 50 mol% to 100 mol%, assuming that all the structural units in the ethylene polymer are 100 mol%, and 60 mol%. More preferably, it is -99 mol%. When the ratio of the structural unit derived from ethylene in the ethylene-based polymer is within the above range, better heat resistance and impact properties are obtained.

When the propylene-based polymer is a copolymer, the copolymer can form a surface layer in which delamination is less likely to occur between the stress relaxation layer and propylene with 2 to 20 carbon atoms. It is preferable that it is a copolymer with an α-olefin (excluding propylene).
The proportion of the structural units derived from propylene in the propylene-based polymer is preferably 50 mol% to 100 mol%, assuming that all the structural units in the propylene-based polymer are 100 mol%, and 60 mol%. More preferably, it is -99 mol%. When the ratio of the structural unit derived from propylene in the propylene-based polymer is within the above range, better heat resistance and impact properties are obtained.

When the butene polymer is a copolymer, the copolymer can form a surface layer in which delamination is less likely to occur between the stress relaxation layer and 1-butene and 1-butene. It is preferable that it is a copolymer with an olefin excluding.
The ratio of the structural unit derived from 1-butene in the butene copolymer is preferably 50 mol% to 100 mol% when all the structural units in the butene polymer are 100 mol%, More preferably, it is 70 mol%-99 mol%. When the ratio of the structural unit derived from 1-butene in the butene polymer is within the above range, the impact property is better.

The melt flow rate (MFR) of the thermoplastic resin C in the first aspect of the present invention is preferably 0.1 g / 10 min to 100 g / 10 min from the viewpoints of film moldability and mechanical properties of the film. More preferably, it is 5g / 10min-50g / 10min.
The melt flow rate (MFR) of the thermoplastic resin C is a value measured in accordance with ASTM D1238. Specifically, the melt flow rate (MFR) of the propylene polymer is a value measured at 230 ° C. with a load of 2.16 kg, and the melt flow rate (MFR) of the ethylene polymer and the butene polymer. ) Is a value measured at 190 ° C. with a load of 2.16 kg.

The density of the thermoplastic resin C in the first aspect of the present invention, from the viewpoint of light ^weight, is preferably from ^{820kg / m 3 ~960kg / m 3} , it is 830kg / ^{m 3} ~940kg / m 3 more ^preferably, it is more preferably ^{860kg / m 3 ~940kg / m 3} .
The density of the thermoplastic resin C is a value measured according to JIS K7112 (density gradient tube method).

The content of the thermoplastic resin C in the surface layer is preferably 50% by mass to 100% by mass and more preferably 70% by mass to 100% by mass with respect to the total mass of the surface layer.
When the content of the thermoplastic resin C is within the above range with respect to the total mass of the surface layer, a surface layer in which delamination is less likely to occur with the stress relaxation layer can be formed.

The surface layer in the laminate according to the first aspect of the present invention may contain other resins other than the above-mentioned thermoplastic resin C within a range not impairing the object of the first aspect of the present invention.
Examples of other resins include styrene copolymers and ethylene / vinyl acetate copolymers (EVA).

[Other layers]
The laminated body of the present invention may contain other layers other than the stress relaxation layer and the surface layer within a range not impairing the object of the first aspect of the present invention.

[Method for producing laminate]
The manufacturing method of the laminated body which concerns on the 1st aspect of this invention is not specifically limited. As a manufacturing method of a layered product concerning the 1st mode of the present invention, 4-methyl-1-pentene copolymer contained as a constituent of a stress relaxation layer, and thermoplastic resin contained as a constituent of a surface layer A method in which C and C are bonded together by mixing in the vicinity of the interface to form a laminate is preferable. Examples of such a method include a co-extrusion method in which a molten resin is laminated, a heat fusion method in which a previously formed resin film is thermally fused, and an interlayer adhesion between a stress relaxation layer and a surface layer. The coextrusion method of laminating a molten resin is more preferable in that a laminate having higher properties and less delamination between the stress relaxation layer and the surface layer can be formed.

  The thickness ratio (surface layer thickness / stress relaxation layer thickness) between the surface layer and the stress relaxation layer in the laminate according to the first aspect of the present invention is 1/99 to 60/40. Is preferable, and it is more preferable that it is 10 / 90-60 / 40.

  The thickness of the laminate according to the first aspect of the present invention is preferably 20 μm to 500 μm, more preferably 20 μm to 350 μm, and 50 μm to 300 μm in terms of easy handling. Is more preferable.

[Surface protective film for semiconductors]
The surface protective film for a semiconductor according to the first aspect of the present invention (hereinafter also simply referred to as “surface protective film”) protects the circuit forming surface of the semiconductor substrate during grinding of the semiconductor substrate. The stress relaxation film which concerns on the 1st aspect of is included. The surface protective film according to the first aspect of the present invention may consist only of the stress relaxation film according to the first aspect of the present invention, or the stress relaxation property according to the first aspect of the present invention. It may be a laminate of a film and other layers. It is desirable that other layers be appropriately selected within a range that does not impair the effects of the stress relaxation film according to the first aspect of the present invention.
Since the surface protective film according to the first aspect of the present invention includes the above-described stress relaxation film according to the first aspect of the present invention, the surface protective film is excellent in stress relaxation and impact resistance. Therefore, according to the surface protective film which concerns on the 1st aspect of this invention, the damage | wound and damage of the circuit formation surface of a semiconductor substrate can be prevented effectively.

[Base material layer]
When the surface protection film according to the first aspect of the present invention includes a base material layer, the base material layer preferably has a high elastic modulus. The base material layer is usually laminated on one surface of the stress relaxation film according to the first aspect of the present invention described above. The surface protection film according to the first aspect of the present invention includes a base material layer, thereby preventing deformation thereof.
As for the elastic modulus of the base material layer, the storage elastic modulus G ′ (25) at 25 ° C. measured at a frequency of 1.6 Hz is preferably 5 × 10 ⁷ Pa or more, and preferably 1 × 10 ⁸ Pa to 2 × 2. It is more preferable that it is × 10 ¹⁰ Pa.
When the storage elastic modulus G ′ (25) of the base material layer is 5 × 10 ⁷ Pa or more, the semiconductor substrate is deformed due to the surface protective film during or after grinding of the semiconductor substrate, and the semiconductor substrate accompanying the deformation It is difficult for cracks to occur.

  The base material layer can be formed into a desired shape and has good affinity with the thermoplastic resin A and the thermoplastic resin B contained in the stress relaxation film according to the first aspect of the present invention. Preferably it consists of. For example, the base material layer is preferably a layer made of polyethylene, ethylene-vinyl acetate copolymer, polypropylene, polyethylene terephthalate, or the like.

  When the surface protection film according to the first aspect of the present invention includes a base material layer, the thickness of the base material layer is preferably 20 μm to 100 μm, and more preferably 38 μm to 50 μm. When the thickness of the base material layer is within the above range, during or after grinding of the semiconductor substrate, deformation of the semiconductor substrate caused by the surface protective film, and cracking of the semiconductor substrate due to the deformation hardly occur, The handleability of the surface protective film is good.

(Adhesive layer)
The surface protective film according to the first aspect of the present invention preferably includes an adhesive layer for adhering to the circuit forming surface of the semiconductor substrate. When the surface protective film according to the first aspect of the present invention includes a base material layer and an adhesive layer, the adhesive layer is on the side where the base material layer of the stress relaxation film according to the first aspect of the present invention is present. It is preferable that it is contained on the opposite side.

  The adhesive layer may be a layer made of an adhesive or the like. The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is not particularly limited, and examples thereof include natural rubber-based; synthetic rubber-based; silicone rubber-based; acrylic pressure-sensitive adhesives such as acrylic acid alkyl esters and methacrylic acid alkyl esters. It is done. Among these, the adhesive is preferably an acrylic adhesive from the viewpoint of adhesiveness.

The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is a pressure-sensitive adhesive having a pressure-sensitive adhesive switching function in which the pressure-sensitive adhesive force is reduced depending on certain conditions such as a radiation-curing type, a heat-curing type, and a heat-foaming type, or a pressure-sensitive adhesive not having the switching function. Either may be sufficient.
In the surface protective film according to the first aspect of the present invention, the adhesive is an acrylic having an adhesive force switching function from the viewpoint that it can be easily peeled off from the circuit forming surface and there is little risk of damaging the circuit forming surface. A UV curable pressure sensitive adhesive is preferred.

  Examples of the acrylic UV curable pressure-sensitive adhesive include 100 parts by mass of an acrylic ester copolymer in which a photopolymerizable carbon-carbon double bond is introduced in the molecule, and a photopolymerizable carbon-carbon in the molecule. Examples thereof include an adhesive containing 0.1 to 20 parts by mass of a low molecular weight compound having two or more double bonds and 5 to 15 parts by mass of a photoinitiator.

  Examples of the acrylic ester copolymer contained in the acrylic UV curable pressure-sensitive adhesive include a copolymer obtained by copolymerizing a monomer having an ethylenic double bond and a copolymerizable monomer having a reactive functional group. Examples thereof include compounds obtained by reacting a combination with a monomer containing a photopolymerizable carbon-carbon double bond having a group capable of reacting with the reactive functional group.

  Examples of the monomer having an ethylenic double bond contained in the copolymer for obtaining an acrylic ester copolymer include, for example, methyl methacrylate, 2-ethylhexyl acrylate, butyl acrylate, ethyl acrylate, etc. Acrylic acid alkyl ester and methacrylic acid alkyl ester monomers; vinyl esters such as vinyl acetate; monomers having an ethylenic double bond such as acrylonitrile; acrylamide; styrene;

  Examples of the copolymerizable monomer having a reactive functional group contained in the copolymer for obtaining an acrylic ester copolymer include (meth) acrylic acid, maleic acid, 2-hydroxyethyl (meta ) Acrylate, glycidyl (meth) acrylate, N-methylol (meth) acrylamide and the like. Only one of these may be polymerized with the monomer having an ethylenic double bond, and two or more of these may be polymerized with the monomer having an ethylenic double bond.

  In the case of obtaining an acrylic ester copolymer, the polymerization ratio of the monomer having an ethylenic double bond and the copolymerizable monomer having a reactive functional group is 70 mass% to 99 mass%: 30 mass% to 30 mass%. It is preferably 1% by mass, more preferably 80% by mass to 95% by mass: 20% by mass to 5% by mass.

  In addition, the monomer containing a photopolymerizable carbon-carbon double bond for obtaining an acrylate ester copolymer is not particularly limited, and a reactive functional group (for example, carboxyl group) contained in the copolymer is not limited. Any photoreactive monomer containing a photopolymerizable carbon-carbon double bond having a group capable of reacting with a group, a hydroxyl group, a glycidyl group and the like.

  Examples of combinations of the reactive functional group contained in the copolymer and the group capable of reacting with the reactive functional group of the photoreactive monomer include a carboxyl group and an epoxy group, a carboxyl group and an aziridyl group, and a hydroxyl group and an isocyanate. Groups and the like. Among such combinations, a combination that easily causes an addition reaction is desirable. In addition, the group capable of reacting with the reactive functional group of the photoreactive monomer is not limited to a group that undergoes an addition reaction with the reactive functional group of the copolymer, and is a group that undergoes a condensation reaction with the reactive functional group of the copolymer. There may be.

Examples of the low molecular weight compound having two or more photopolymerizable carbon-carbon double bonds in the molecule contained in the acrylic UV-curable pressure-sensitive adhesive include tripropylene glycol di (meth) acrylate and trimethylolpropane tri (Meth) acrylate, tetramethylolmethane tetraacrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol monohydroxypenta (meth) acrylate, dipentaerythritol hexa (meth) acrylate and the like. Only one type of low molecular weight compound may be contained in the acrylic ultraviolet curable pressure-sensitive adhesive, or two or more types may be contained.
The “low molecular weight compound” as used herein refers to a compound having a molecular weight of 10,000 or less, and the molecular weight of the low molecular weight compound is more preferably 5,000 or less.

  Examples of the photoinitiator contained in the acrylic ultraviolet curable adhesive include, for example, benzoin, isopropyl benzoin ether, isobutyl benzoin ether, benzophenone, Michler ketone, chlorothioxanthone, dodecylthioxanthone, dimethylthioxanthone, diethylthioxanthone, acetophenone diethyl ketal, benzyl Examples include dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, and 2-hydroxy-2-methyl-1-phenylpropan-1-one. As for a photoinitiator, only 1 type may be contained in the ultraviolet curing adhesive, and 2 or more types may be contained. The content of the photoinitiator in the ultraviolet curable adhesive is preferably 5 parts by mass to 15 parts by mass with respect to 100 parts by mass of the acrylic ester copolymer, and is 5 parts by mass to 10 parts by mass. More preferably.

  The acrylic ultraviolet curable pressure-sensitive adhesive may contain a crosslinking agent. Examples of the cross-linking agent include epoxy compounds such as sorbitol polyglycidyl ether, polyglycerol polyglycidyl ether, pentaerythritol polyglycidyl ether, diglycerol polyglycidyl ether; tetramethylolmethane-tri-β-aziridinyl propionate, Trimethylolpropane-tri-β-aziridinylpropionate, N, N′-diphenylmethane-4,4′-bis (1-aziridinecarboxamide), N, N′-hexamethylene-1,6-bis ( Aziridine compounds such as 1-aziridinecarboxamide); isocyanate compounds such as tetramethylene diisocyanate, hexamethylene diisocyanate, and polyisocyanate.

  The acrylic ultraviolet curable pressure-sensitive adhesive may contain rosin resin-based, terpene resin-based tackifiers, various surfactants, and the like. According to these, it is possible to adjust the adhesive properties of the acrylic ultraviolet curable adhesive.

  When the surface protective film which concerns on the 1st aspect of this invention contains an adhesion layer, the thickness of this adhesion layer is not specifically limited, It is preferable that it is 3-100 micrometers, and it is 10-100 micrometers. Is more preferable. When the thickness of the adhesive layer is within the above range, sufficient adhesiveness can be obtained, and the effect of the stress relaxation film according to the first aspect of the present invention is hardly impaired.

The adhesive strength of the surface protective film according to the first aspect of the present invention including the adhesive layer is preferably 0.1 N / 25 mm to 5 N / 25 mm in terms of adhesive strength with respect to the SUS304-BA plate, and 0.1 N It is more preferable that it is / 25mm-3N / 25mm. When the adhesive strength of the surface protective film is within the above range, the surface protective film can be sufficiently adhered to the circuit forming surface of the semiconductor substrate, and when the surface protective film is peeled off from the circuit forming surface In addition, the semiconductor substrate is hardly damaged, and further, the adhesive layer hardly remains on the circuit forming surface after the surface protective film is peeled off from the circuit forming surface of the semiconductor substrate.
In addition, when the adhesive has an adhesive force switching function such as a radiation curable type, a thermosetting type, a heated foam type, etc., the adhesive force after the adhesive force is switched and reduced by radiation irradiation or the like is within the above range. It is preferable to be within.

[Other layers]
The surface protective film according to the first aspect of the present invention may include, for example, another layer having a low elastic modulus between the stress relaxation film according to the first aspect of the present invention and the adhesive layer. . The elastic modulus of the other layers is preferably lower than the elastic modulus of the stress relaxation film according to the first aspect of the present invention. As specific elastic modulus of the other layers, the storage elastic modulus G ′ (25) at 25 ° C. measured at a frequency of 1.6 Hz is preferably 8 × 10 ⁶ Pa or less, preferably 1 × 10 ⁴ Pa to More preferably, it is 8 × 10 ⁶ Pa. When the storage elastic modulus G ′ (25) of the other layers is 8 × 10 ⁶ Pa or less, the effect of the stress relaxation film according to the first aspect of the present invention is hardly impaired.

  Other layers include, for example, ethylene-vinyl acetate copolymer, ethylene-alkyl acrylate copolymer (alkyl group having 1 to 4 carbon atoms), low density polyethylene, ethylene-α-olefin copolymer (α-olefin). And a resin layer containing 3 to 8 carbon atoms. Among these, it is preferable that another layer is a resin layer containing the ethylene-vinyl acetate copolymer whose content of a vinyl acetate unit is 5 mass%-50 mass%.

[Method for producing surface protective film]
The method for producing the surface protective film according to the first aspect of the present invention is not particularly limited. For example, the surface protection film including the stress relaxation film, the base material layer, and the adhesive layer according to the first aspect of the present invention is formed by laminating the stress relaxation film according to the first aspect of the present invention and the base material layer. Furthermore, it is obtained by forming an adhesive layer on the side opposite to the side where the base material layer of the stress relaxation film is present.

  As a method of laminating the stress relaxation film and the base material layer according to the first aspect of the present invention, for example, a resin and a base material layer that form the stress relaxation film according to the first aspect of the present invention are formed. A method of extruding a resin with a multilayer film forming machine, a stress relaxation film and a base material layer according to the first aspect of the present invention, respectively, such as a calendar method, a T-die extrusion method, an inflation method, a casting method, etc. Examples of the method include forming a film by a known method and then laminating these by dry lamination. In the latter case, in order to increase the adhesive force between the stress relaxation film and the base material layer according to the first aspect of the present invention, a new adhesive layer may be formed between the two, or the present invention. Each of the stress relaxation film and the base material layer according to the first aspect may be subjected to easy adhesion treatment such as corona discharge treatment.

  The pressure-sensitive adhesive layer is a known method such as a roll coater, a comma coater, a die coater, a Mayer bar coater, a reverse roll coater, a gravure coater, etc. Thus, it can be formed by applying on the stress relaxation film according to the first aspect of the present invention and drying. After forming the adhesive layer, it is preferable to stick a release film on the surface of the adhesive layer in order to prevent contamination of the adhesive layer.

  After applying the pressure-sensitive adhesive coating solution on one surface of the release film by the above method and drying to form a pressure-sensitive adhesive layer, the stress according to the first aspect of the present invention is applied to the pressure-sensitive adhesive layer by a dry laminating method or the like. You may transfer on a relaxation film.

  Drying conditions for drying the pressure-sensitive adhesive coating solution are not particularly limited, and in general, drying is preferably performed for 10 seconds to 10 minutes in a temperature range of 80 ° C. to 300 ° C. It is more preferable to dry in the temperature range of 200 ° C. for 15 seconds to 5 minutes. Further, after the drying of the pressure-sensitive adhesive coating solution, the surface protective film may be heated at 40 ° C. to 80 ° C. for about 5 hours to 300 hours.

  In the surface protective film according to the first aspect of the present invention, from the viewpoint of preventing contamination of the circuit forming surface of the semiconductor substrate, all of the stress relaxation film, the base material layer, the adhesive layer, and the like according to the first aspect of the present invention. It is preferable that the film forming environment and the manufacturing environment for these raw materials are maintained at a cleanness of class 1,000 or less as defined in the US Federal Standard 209b.

[Method of Manufacturing Semiconductor Device]
According to a first aspect of the present invention, there is provided a semiconductor device manufacturing method comprising: a preparatory step of preparing a semiconductor substrate having a circuit formed only on one surface; An adhesion step of adhering the surface protective film according to the embodiment so that the adhesive layer of the surface protective film and the circuit forming surface of the semiconductor substrate face each other, and grinding the circuit non-forming surface of the semiconductor substrate And a peeling step of peeling the surface protection film attached to the circuit forming surface of the semiconductor substrate from the circuit forming surface of the semiconductor substrate.

In a general method for manufacturing a semiconductor device, a circuit is formed on one surface of a semiconductor substrate having a thickness of about 500 μm to 1000 μm. Thereafter, the surface on which the circuit is not formed (circuit non-formation surface) is ground to thin the semiconductor substrate.
The preparation step is a step of preparing a thick semiconductor substrate before grinding the non-circuit-formed surface. Examples of the semiconductor substrate include substrates such as a silicon wafer, germanium, gallium-arsenic, gallium-phosphorus, and gallium-arsenic-aluminum.

In the attaching step, the surface protective film according to the first aspect of the present invention is opposed to the circuit forming surface of the semiconductor substrate, and the adhesive layer of the surface protective film and the circuit forming surface of the semiconductor substrate are opposed to each other. It is the process of sticking.
The sticking may be performed manually, but is usually performed by an automatic sticking machine equipped with a roll-shaped surface protective film. As an automatic pasting machine, for example, Takatori Co., Ltd., model: ATM-1000B, ATM-1100, TEAM-100, Teikoku Seiki Co., Ltd., model: STL series, Nitto Seiki Co., Ltd., model : DR-8500II, DR-3000II and the like.

The grinding process is a process of grinding the circuit non-formed surface of the semiconductor substrate.
The grinding can be performed by a known method such as a through-feed method or an in-feed method. In either method, the semiconductor substrate is ground with a grindstone.

  The temperature of the semiconductor substrate at the start of the grinding process is usually about 18 ° C. to 28 ° C., preferably 20 ° C. to 25 ° C. Further, the temperature of the semiconductor substrate during the grinding process depends on the material of the substrate to be ground, but is usually 20 ° C to 120 ° C, preferably 30 ° C to 80 ° C, and preferably 40 ° C to 70 ° C. It is more preferable.

  After the grinding step, the non-circuit-formed surface of the semiconductor substrate may be further processed as necessary. The non-circuit-formed surface is processed by fixing the semiconductor substrate to a chuck table or the like of a back surface processing machine via a surface protective film. Examples of the treatment of the circuit non-formation surface include polishing of the semiconductor substrate, chemical etching, dry etching, plasma treatment, etc., and removal of distortion generated on the circuit non-formation surface of the semiconductor substrate or further thinning of the semiconductor substrate. Layering, removal of oxide film, etc., processing before electrode formation, etc. are performed.

  Moreover, you may perform the process of sticking the adhesive film for die bonding to the back surface of a semiconductor substrate after the said grinding process. As an apparatus for sticking the die bonding adhesive film, there are, for example, Takatori Co., Ltd., model: ATM-8200, DM-800, and the like. Recently, a so-called inline back surface processing machine in which the back surface processing unit, the die bonding adhesive film attaching unit, and the surface protection film peeling unit are integrated has been put into practical use. As such an in-line back surface processing machine, for example, model name: PG300RM manufactured by Tokyo Seimitsu Co., Ltd. may be mentioned.

Stripping step after the grinding step, the surface protection film is adhered to a circuit forming surface of the semi-conductor substrate, a step of peeling from the circuit formation surface of the semiconductor substrate.
The surface protective film may be peeled off by a human hand, but is generally carried out by an apparatus called an automatic peeling machine. As an automatic peeling machine, for example, Takatori Co., Ltd., Model: ATRM-2000B, ATRM-2100, Teikoku Seiki Co., Ltd., Model: STP Series, Nitto Seiki Co., Ltd., Model: HR8500-II, etc. There is. Moreover, in order to improve the peelability of the surface protective film, the surface protective film may be peeled while heating the semiconductor substrate.

  The circuit forming surface of the semiconductor substrate after peeling off the surface protective film is washed as necessary. Examples of the cleaning method include wet cleaning such as water cleaning and solvent cleaning, and dry cleaning such as plasma cleaning. In the case of wet cleaning, ultrasonic cleaning may be used in combination. These cleaning methods are appropriately selected depending on the contamination state of the semiconductor substrate surface.

  According to the manufacturing method of the semiconductor device according to the first aspect of the present invention, the stress relaxation film according to the first aspect of the present invention is adhered to the circuit forming surface of the semiconductor substrate. During grinding of the forming surface, there is no possibility that the circuit forming surface is scratched or dust is attached. Further, it is possible to prevent the thin semiconductor substrate from being damaged during the grinding process.

<< Second aspect >>
[Stress relaxation film]
The stress relaxation film which concerns on the 2nd aspect of this invention is a structure derived from 70 mol%-90 mol% of the structural unit derived from 4-methyl-1- pentene, and a C2-C3 alpha olefin. Heat which is a copolymer containing 10 mol% to 30 mol% of units and having a proportion of structural units derived from an α-olefin having 4 to 20 carbon atoms other than 4-methyl-1-pentene. The thermoplastic resin, which is a plastic resin A and at least one polymer selected from the group consisting of an ethylene polymer, a propylene polymer, a butene polymer, and a 4-methyl-1-pentene polymer. A thermoplastic resin B other than A, and the content of the thermoplastic resin A is 2% by mass or more and less than 50% by mass with respect to the total mass, and the content of the thermoplastic resin B is the total mass 50 mass% or more 98 quality % Or less.
According to the stress relaxation film according to the second aspect of the present invention, delamination hardly occurs when the film has a certain degree of stress relaxation and is laminated with another layer.

A film used for protecting an object from scratches or breakage due to external force (hereinafter also referred to as “protective film”) is required to have characteristics such as stress relaxation properties, for example.
The present inventors have found a specific thermoplastic resin containing a large amount of 4-methyl-1-pentene as a resin responsible for stress relaxation. However, although a film formed only of the thermoplastic resin has high stress relaxation properties, it has high release properties, and delamination is likely to occur when it is laminated with other layers.
In the second aspect of the present invention, the film comprises a specific thermoplastic resin A containing a large amount of 4-methyl-1-pentene responsible for stress relaxation and a specific thermoplastic resin responsible for adhesion and adhesion. By making it into the aspect which contains B in a specific ratio, the film which has a certain degree of high stress relaxation property, and does not produce delamination easily when laminated | stacked with another layer is implement | achieved.

  Hereinafter, the components contained in the stress relaxation film according to the second aspect of the present invention will be described.

[Thermoplastic resin A]
The thermoplastic resin A in the second aspect of the present invention is synonymous with the thermoplastic resin A in the first aspect of the present invention, except for the following points, and a preferred range (for example, 4-methyl-1-pentene-based). Copolymer structural unit and content thereof, physical properties of 4-methyl-1-pentene copolymer (for example, intrinsic viscosity [η], weight average molecular weight (Mw), molecular weight distribution (Mw / Mn), melt flow) The rate (MFR), density, melting point (Tm), etc.) and the measurement method, synthesis method, etc.) and the reason are the same.

The 4-methyl-1-pentene copolymer in the second aspect of the present invention contains 70 mol% to 90 mol% of a structural unit derived from 4-methyl-1-pentene, and 70 mol % To 88 mol% is more preferable, and 70 mol% to 86 mol% is further more preferable.
When the structural unit derived from 4-methyl-1-pentene contained in the 4-methyl-1-pentene-based copolymer is less than 70 mol%, high stress relaxation properties required for the protective film can be obtained. Can not. Moreover, when the structural unit derived from 4-methyl-1-pentene contained in the 4-methyl-1-pentene-based copolymer exceeds 90 mol%, the releasability becomes too high, so that it is laminated with other layers. When delaminated, delamination occurs.

The 4-methyl-1-pentene copolymer according to the second aspect of the present invention contains 10 to 30 mol% of a structural unit derived from an α-olefin having 2 or 3 carbon atoms, It is more preferable that 11 mol%-30 mol% are contained, and it is still more preferable that 14 mol%-30 mol% is contained.
When the structural unit derived from the α-olefin having 2 or 3 carbon atoms contained in the 4-methyl-1-pentene copolymer is less than 10 mol%, the rigidity of the material is excessively increased, so that appropriate stress relaxation properties are obtained. Cannot be obtained. Moreover, when the structural unit derived from the α-olefin having 2 or 3 carbon atoms contained in the 4-methyl-1-pentene copolymer exceeds 30 mol%, the crystallinity is lowered and the melting point is not observed. Softening advances and film forming becomes difficult.

  The structural unit derived from an α-olefin having 2 or 3 carbon atoms is a structural unit derived from ethylene or propylene. In the present invention, from the viewpoint of stress relaxation, the structural unit derived from an α-olefin having 2 or 3 carbon atoms is particularly preferably a structural unit derived from propylene.

The content of the thermoplastic resin A in the stress relaxation film according to the second aspect of the present invention is 2% by mass or more and less than 50% by mass, and 5% by mass or more and 48% by mass with respect to the total mass of the stress relaxation film. The content is preferably at most 10 mass%, more preferably at least 10 mass% and at most 45 mass%.
When the content of the thermoplastic resin A is less than 2% by mass with respect to the total mass of the stress relaxation film, it is not possible to obtain a high level of stress relaxation necessary for the protective film.
When the content of the thermoplastic resin A is 50% by mass or more with respect to the total mass of the stress relaxation film, the releasability becomes too high, and thus delamination occurs when laminated with other layers. .

[Thermoplastic resin B]
The thermoplastic resin B in the second aspect of the present invention is synonymous with the thermoplastic resin B in the first aspect of the present invention, except for the following points, and preferred ranges (for example, composition, physical properties (melt flow rate ( MFR), density, etc.) and measurement methods thereof) and the reason are the same.

The content of the thermoplastic resin B in the stress relaxation film according to the second aspect of the present invention is 50% by mass or more and 98% by mass or less, and 52% by mass or more and 95% by mass with respect to the total mass of the stress relaxation film. It is preferable that it is mass% or less, and it is more preferable that it is 55 mass% or more and 90 mass% or less.
When the content of the thermoplastic resin B is less than 50% by mass with respect to the total mass of the stress relaxation film, sufficient adhesiveness and adhesion cannot be expressed, and the other layers are laminated. In some cases, delamination occurs.
When the content of the thermoplastic resin B exceeds 98% by mass with respect to the total mass of the stress relaxation film, it is not possible to obtain a high level of stress relaxation necessary for the protective film.

[Other resins]
The stress relaxation film according to the second aspect of the present invention contains other resins other than the above-described thermoplastic resin A and thermoplastic resin B within a range not impairing the object of the second aspect of the present invention. It may be.

[Structure of stress relaxation film]
The stress relieving film according to the second aspect of the present invention preferably has a sea-island structure composed of an island part including the thermoplastic resin A and a sea part substantially composed of the thermoplastic resin B. .
In the present invention, the sea part “consisting essentially of the thermoplastic resin B” means that the content of the thermoplastic resin B in the sea part is 70% by mass or more based on the total mass of the constituent components of the sea part. To do.

The stress relieving film of the present invention having a sea-island structure composed of an island part including the thermoplastic resin A and a sea part substantially consisting of the thermoplastic resin B has a higher stress relaxation property. And when other layers are laminated, delamination is less likely to occur. The reason why such an effect is achieved is not clear, but the present inventors presume as follows.
Adhesion performance and adhesion performance by the thermoplastic resin B are more effectively exhibited when the thermoplastic resin B responsible for adhesion and adhesion becomes a sea part. As a result, even when other layers are laminated, delamination is less likely to occur. Moreover, the thermoplastic resin A which bears stress relaxation becomes an island part, and the stress relaxation performance by the thermoplastic resin A is more effectively exhibited by dispersing in the film. As a result, the stress relaxation property of the film becomes higher.

  In addition, the stress relaxation film according to the second aspect of the present invention has a sea-island structure including an island part including the thermoplastic resin A and a sea part substantially made of the thermoplastic resin B. This can be confirmed by, for example, a transmission electron microscope (TEM). Specifically, the film is ground to produce an ultrathin section, and only one of the components is selectively stained with a heavy metal such as ruthenium tetroxide or osmium tetroxide, and then observed using a transmission electron microscope. To do.

  A film having a sea-island structure composed of an island part including the thermoplastic resin A and a sea part substantially composed of the thermoplastic resin B is, for example, a dry blend of the thermoplastic resin A and the thermoplastic resin B. Obtained by mixing and extrusion to form a film.

[Manufacturing method of stress relaxation film]
An example of the manufacturing method of the stress relaxation film which concerns on the 2nd aspect of this invention is demonstrated. The stress relaxation film according to the second aspect of the present invention can be produced, for example, by the following method. However, the second aspect of the present invention is not limited to the following method.
The thermoplastic resin A and the thermoplastic resin B are mixed (for example, dry blended). From the viewpoint of forming the above-mentioned sea-island structure, it is preferable to appropriately knead the thermoplastic resin A and the thermoplastic resin B by dry blending or the like rather than uniformly mixing them by melt kneading or the like.
Subsequently, the obtained mixture is put into a hopper of an extruder provided with a T die, and the cylinder temperature is set to 100 ° C. to 270 ° C. and the die temperature is set to 200 ° C. to 270 ° C. The melt-kneaded material is extruded from a T die and cast to obtain a stress relaxation film.

  The thickness of the stress relaxation film according to the second aspect of the present invention is preferably 50 μm to 350 μm, more preferably 60 μm to 300 μm, and still more preferably 70 μm to 200 μm. When the thickness of the stress relaxation film according to the second aspect of the present invention is within the above range, handleability is easy.

[Use of stress relaxation film]
The stress relaxation film according to the second aspect of the present invention is used for the purpose of preventing scratches and dust prevention during transportation, storage, processing, etc. of various resin products such as building materials and optical parts, metal products, and glass products. The protective film can be suitably used as a protective film adhered to these surfaces.

In addition, the stress relaxation film according to the second aspect of the present invention can be used to grind the circuit non-formation surface of the semiconductor substrate so that the semiconductor substrate has a desired thickness. It can be particularly suitably used as a protective film for preventing breakage.
Since the stress relaxation film according to the second aspect of the present invention has stress relaxation properties, it is effective in preventing damage and breakage of the circuit formation surface of the semiconductor substrate. In addition, since the stress relaxation film according to the second aspect of the present invention hardly causes delamination even when other layers are laminated, the semiconductor substrate is adhered to a circuit forming surface. Workability such as peeling from the circuit forming surface is good.

[Laminate]
The laminate according to the second aspect of the present invention includes a stress relaxation layer comprising the stress relaxation film according to the second aspect of the present invention, an ethylene polymer, a propylene polymer, and a butene polymer. A thermoplastic resin C which is at least one polymer selected from the group consisting of: and a surface layer at least partially in contact with the stress relaxation layer.
The laminate according to the second aspect of the present invention has a somewhat high stress relaxation property, and is less likely to cause delamination when laminated with other layers, according to the second aspect of the present invention described above. Since a stress relaxation layer made of a stress relaxation film is included, the stress relaxation property is high to some extent, and delamination does not easily occur between the stress relaxation layer and the layer in contact with the stress relaxation layer.

(Stress relaxation layer)
The stress relaxation layer in the laminate according to the second aspect of the present invention is composed of the stress relaxation film according to the second aspect of the present invention described above. In addition, since it mentioned above about the stress relaxation film which concerns on the 2nd aspect of this invention, description is abbreviate | omitted here.

[Surface layer]
The surface layer in the laminated body according to the second aspect of the present invention is synonymous with the surface layer in the laminated body according to the first aspect of the present invention, and the preferred range (for example, composition, location, stress relaxation layer) The contact ratio etc.) and the reason are the same.

(Thermoplastic resin C)
The thermoplastic resin C in the second aspect of the present invention is synonymous with the thermoplastic resin C in the first aspect of the present invention, and preferred ranges (for example, composition, physical properties (melt flow rate (MFR), density, etc.)). And the measuring method, the content in the surface layer, etc.) and the reason are the same.

[Other layers]
The laminated body according to the second aspect of the present invention may include other layers other than the stress relaxation layer and the surface layer, as long as the object of the second aspect of the present invention is not impaired.

[Method for producing laminate]
The method for manufacturing a laminate according to the second aspect of the present invention is the same as the method for manufacturing the laminate according to the first aspect of the present invention, and preferred ranges (for example, manufacturing conditions, surface layer and stress relaxation layer) The thickness ratio (the thickness of the surface layer / the thickness of the stress relaxation layer, the thickness of the laminated body, etc.) and the reason are the same.

[Surface protective film for semiconductors]
The semiconductor surface protective film according to the second aspect of the present invention (hereinafter also simply referred to as “surface protective film”) protects the circuit forming surface of the semiconductor substrate during grinding of the semiconductor substrate. The stress relaxation film which concerns on the 2nd aspect of is included. The surface protective film according to the second aspect of the present invention may consist only of the stress relaxation film according to the second aspect of the present invention, or the stress relaxation property according to the second aspect of the present invention. It may be a laminate of a film and other layers. It is desirable that other layers are appropriately selected as long as the effects of the stress relaxation film according to the second aspect of the present invention are not impaired.

Since the surface protective film according to the second aspect of the present invention includes the above-described stress relaxation film according to the second aspect of the present invention, the surface protective film has a somewhat high stress relaxation property. Therefore, according to the surface protective film which concerns on the 2nd aspect of this invention, the damage and damage of the circuit formation surface of a semiconductor substrate can be prevented effectively.
Further, when the surface protective film according to the second aspect of the present invention is a laminate of the above-described stress relaxation film according to the second aspect of the present invention and another layer, delamination hardly occurs. Therefore, operations such as attaching the semiconductor substrate to the circuit formation surface and peeling the semiconductor substrate from the circuit formation surface can be performed satisfactorily.

[Base material layer]
The base material layer that can be included in the surface protective film according to the second aspect of the present invention is synonymous with the base material layer that can be included in the surface protective film according to the first aspect of the present invention, and a preferred range (for example, The elastic modulus, location, composition, thickness, etc.) and the reason are the same.

(Adhesive layer)
The pressure-sensitive adhesive layer that can be included in the surface protective film according to the second aspect of the present invention is synonymous with the pressure-sensitive adhesive layer that can be included in the surface protective film according to the first aspect of the present invention, and a preferred range (for example, the location) The adhesive layer constituting the adhesive layer, the thickness, the adhesive force, etc.) and the reason are the same.

[Other layers]
The other layer that can be included in the surface protective film according to the second aspect of the present invention is synonymous with the other layer that can be included in the surface protective film according to the first aspect of the present invention, and a preferred range (for example, The elastic modulus, composition, etc.) and the reason are the same.

[Method for producing surface protective film]
The method for producing the surface protective film according to the second aspect of the present invention is the same as the method for producing the surface protective film according to the first aspect of the present invention, and the preferred range (for example, production conditions) and the reason thereof are also included. It is the same.

[Method of Manufacturing Semiconductor Device]
The manufacturing method of the semiconductor device according to the second aspect of the present invention is the same as the manufacturing method of the semiconductor device according to the first aspect of the present invention, and the preferable range (for example, manufacturing conditions) and the reason are the same. is there.

According to the method for manufacturing a semiconductor device according to the second aspect of the present invention, the stress relaxation film according to the second aspect of the present invention is adhered to the circuit forming surface of the semiconductor substrate. During grinding of the forming surface, there is no fear that the circuit forming surface is scratched or dust is attached, and it is possible to prevent the thin semiconductor substrate from being damaged during the grinding process.
In the method for manufacturing a semiconductor device according to the second aspect of the present invention, when the stress relaxation film according to the second aspect of the present invention, which is adhered to the circuit forming surface of the semiconductor substrate, is a laminate with other layers. Since the delamination hardly occurs, the sticking work can be performed well.

[Resin modifier]
The resin modifier which concerns on the 2nd aspect of this invention is a structure derived from 70 mol%-90 mol% of structural units derived from 4-methyl-1- pentene, and a C2-C3 alpha olefin. Heat which is a copolymer containing 10 mol% to 30 mol% of units and having a proportion of structural units derived from an α-olefin having 4 to 20 carbon atoms other than 4-methyl-1-pentene. The thermoplastic resin, which is a plastic resin A and at least one polymer selected from the group consisting of an ethylene polymer, a propylene polymer, a butene polymer, and a 4-methyl-1-pentene polymer. A thermoplastic resin B other than A, and the content of the thermoplastic resin A is 2% by mass or more and less than 50% by mass with respect to the total mass, and the content of the thermoplastic resin B is the total mass 50 mass% or more and 98 mass% or less It is.
According to the resin modifier according to the second aspect of the present invention, the resin is imparted with a certain degree of high stress relaxation and adhesion that is difficult to delaminate when laminated with other layers. Can do.

The thermoplastic resin A and the thermoplastic resin B in the resin modifier according to the second aspect of the present invention have the same meaning as the thermoplastic resin A and the thermoplastic resin B described in the section of the stress relaxation film, respectively. Since the aspect is also the same, the description is omitted here.
In addition, regarding the content of the thermoplastic resin A and the content of the thermoplastic resin B in the resin modifier according to the second aspect of the present invention, the content of the thermoplastic resin A described in the section of the stress relaxation film, respectively. The amount and the content of the thermoplastic resin B are synonymous, and the preferred embodiment is also the same, and thus the description thereof is omitted here.

The resin to be modified by the resin modifier according to the second aspect of the present invention is not particularly limited. The resin to be modified by the resin modifier according to the second aspect of the present invention is ethylene from the viewpoint of rigidity of the base material, heat resistance, stress relaxation effect due to dispersion state with the thermoplastic resin A, and the like. Of these, a polymer, a propylene polymer, a butene polymer and the like are preferable.
The resin modifier according to the second aspect of the present invention is preferably blended in an amount of 5 to 50 parts by weight, preferably 10 to 45 parts by weight, based on 100 parts by weight of the resin to be modified. It is more preferable.

  The resin modifier according to the second aspect of the present invention contains a specific amount of thermoplastic resin A and a specific amount of thermoplastic resin B, and further does not impair the purpose of the second aspect of the present invention. Inside, for example, weathering stabilizer, heat stabilizer, antioxidant, ultraviolet absorber, antistatic agent, anti-slip agent, anti-blocking agent, anti-fogging agent, nucleating agent, lubricant, pigment, dye, anti-aging agent, Various additives such as a hydrochloric acid absorbent, an inorganic or organic filler, an organic or inorganic foaming agent, a cross-linking agent, a cross-linking aid, a pressure-sensitive adhesive, a softening agent, and a flame retardant may be contained.

  Hereinafter, the first aspect and the second aspect of the present invention will be described more specifically with reference to examples. The first and second aspects of the present invention are not limited to the following examples as long as they do not exceed the gist thereof.

<< Example of the first aspect >>
[Synthesis Example 1A] Synthesis of Copolymer A-1A To a SUS autoclave with a 1.5 L stirring blade sufficiently purged with nitrogen, 300 ml of n-hexane (dried on activated alumina in a dry nitrogen atmosphere) ), And 450 ml of 4-methyl-1-pentene were charged at 23 ° C., then, 0.75 ml of a 1.0 mmol / ml toluene solution of triisobutylaluminum (TIBAL) was charged, and the stirrer was rotated.
Next, the autoclave was heated until the internal temperature reached 60 ° C., and pressurized with propylene so that the total pressure (gauge pressure) was 0.19 MPa.
Subsequently, 1 mmol of methylaluminoxane and 0.01 mmol of diphenylmethylene (1-ethyl-3-t-butyl-cyclopentadienyl) (2,7-di-dioxide) prepared in advance in terms of aluminum (Al) were prepared. -T-butyl-fluorenyl) 0.34 ml of a toluene solution containing zirconium dichloride was pressed into the autoclave with nitrogen to initiate the polymerization reaction. During the polymerization reaction, the temperature was adjusted so that the internal temperature of the autoclave was 60 ° C.
Sixty minutes after the start of the polymerization, 5 ml of methanol was pressed into the autoclave with nitrogen to stop the polymerization reaction, and then the inside of the autoclave was depressurized to the atmospheric pressure. After depressurization, acetone was added to the reaction solution while stirring the reaction solution to obtain a polymerization reaction product containing a solvent. Subsequently, the polymerization reaction product containing the obtained solvent was dried at 130 ° C. under reduced pressure for 12 hours to obtain 44.0 g of a powdery copolymer A-1A.

Table 1 shows the measurement results of various physical properties of the obtained copolymer A-1A.
The content of 4-methyl-1-pentene in copolymer A-1A was 84.1 mol%, and the content of propylene was 15.9 mol%. Further, the density of the copolymer A-1A was 838 kg / m ³ . Copolymer A-1A had an intrinsic viscosity [η] of 1.5 dl / g, a weight average molecular weight (Mw) of 340,000, and a molecular weight distribution (Mw / Mn) of 2.1. The melting point (Tm) of the copolymer A-1A was 132 ° C., and the maximum value of tan δ was 1.6 (temperature when showing the maximum value: 39 ° C.).

[Synthesis Example 2A] Synthesis of Copolymer A-2A To a SUS autoclave with a 1.5-liter stirring blade sufficiently purged with nitrogen, 300 ml of n-hexane (dried on activated alumina in a dry nitrogen atmosphere) ), And 450 ml of 4-methyl-1-pentene were charged at 23 ° C., then, 0.75 ml of a 1.0 mmol / ml toluene solution of triisobutylaluminum (TIBAL) was charged, and the stirrer was rotated.
Next, the autoclave was heated to an internal temperature of 60 ° C. and pressurized with propylene so that the total pressure (gauge pressure) was 0.40 MPa.
Subsequently, 1 mmol of methylaluminoxane and 0.01 mmol of diphenylmethylene (1-ethyl-3-t-butyl-cyclopentadienyl) (2,7-di-t-) prepared in advance were converted into Al. 0.34 ml of a toluene solution containing (butyl-fluorenyl) zirconium dichloride was pressed into the autoclave with nitrogen to initiate the polymerization reaction. During the polymerization reaction, the temperature was adjusted so that the internal temperature of the autoclave was 60 ° C.
Sixty minutes after the start of the polymerization, 5 ml of methanol was pressed into the autoclave with nitrogen to stop the polymerization reaction, and then the inside of the autoclave was depressurized to the atmospheric pressure. After depressurization, acetone was added to the reaction solution while stirring the reaction solution to obtain a polymerization reaction product containing a solvent. Next, the polymerization reaction product containing the obtained solvent was dried at 130 ° C. under reduced pressure for 12 hours to obtain 36.9 g of a powdery copolymer A-2A.

Table 1 shows the measurement results of various physical properties of the obtained copolymer A-2A.
The content of 4-methyl-1-pentene in the copolymer A-2A was 72.5 mol%, and the content of propylene was 27.5 mol%. Further, the density of the copolymer A-2A was 839 kg / m ³ . Copolymer A-2A had an intrinsic viscosity [η] of 1.5 dl / g, a weight average molecular weight (Mw) of 337,000, and a molecular weight distribution (Mw / Mn) of 2.1. The melting point (Tm) of the copolymer A-2A was not observed, and the maximum value of tan δ was 2.8 (temperature when showing the maximum value: 31 ° C.).

[Synthesis Example 3A] Synthesis of Copolymer A-3A (Comparative Copolymer) 750 ml of 4-methyl-1-pentene was placed at 23 ° C. in a SUS autoclave with a 1.5 L stirring blade sufficiently purged with nitrogen. Then, 0.75 ml of a 1.0 mmol / ml toluene solution of triisobutylaluminum (TIBAL) was charged, and the stirrer was rotated.
Next, the autoclave was heated until the internal temperature reached 60 ° C., and pressurized with propylene so that the total pressure (gauge pressure) was 0.15 MPa.
Subsequently, 1 mmol of methylaluminoxane and 0.005 mmol of diphenylmethylene (1-ethyl-3-t-butyl-cyclopentadienyl) (2,7-di-t-) prepared in advance were converted into Al. 0.34 ml of a toluene solution containing (butyl-fluorenyl) zirconium dichloride was pressed into the autoclave with nitrogen to initiate the polymerization reaction. During the polymerization reaction, the temperature was adjusted so that the internal temperature of the autoclave was 60 ° C.
Sixty minutes after the start of the polymerization, 5 ml of methanol was pressed into the autoclave with nitrogen to stop the polymerization reaction, and then the inside of the autoclave was depressurized to the atmospheric pressure. After depressurization, acetone was added to the reaction solution while stirring the reaction solution to obtain a polymerization reaction product containing a solvent. Subsequently, the polymerization reaction product containing the obtained solvent was dried at 130 ° C. under reduced pressure for 12 hours to obtain 45.9 g of a powdery copolymer A-3A.

Table 1 shows the measurement results of various physical properties of the obtained copolymer A-3A.
The content of 4-methyl-1-pentene in the copolymer A-3A was 92.3 mol%, and the content of propylene was 7.7 mol%. Further, the density of the copolymer A-3A was 832 kg / m ³ . Copolymer A-3A had an intrinsic viscosity [η] of 1.6 dl / g, a weight average molecular weight (Mw) of 370,000, and a molecular weight distribution (Mw / Mn) of 2.1. The melting point (Tm) of the copolymer A-3A was 178 ° C., and the maximum value of tan δ was 0.4 (temperature when showing the maximum value: 40 ° C.).

  Methods for measuring various physical properties of the copolymer are shown below.

〔composition〕
The content (mol%) of 4-methyl-1-pentene and propylene (C3 α-olefin) in the copolymer was measured by ¹³ C-NMR. The measurement conditions are as follows.

~conditions~
Measuring apparatus: Nuclear magnetic resonance apparatus (ECP500 type, manufactured by JEOL Ltd.)
Observation nucleus: ¹³ C (125 MHz)
Sequence: Single pulse proton decoupling Pulse width: 4.7 μsec (45 ° pulse)
Repeat time: 5.5 seconds Accumulated number: 10,000 times or more Solvent: Orthodichlorobenzene / deuterated benzene (volume ratio: 80/20) mixed solvent Sample concentration: 55 mg / 0.6 mL
Measurement temperature: 120 ° C
Standard value of chemical shift: 27.50ppm

[Intrinsic viscosity [η]]
The intrinsic viscosity [η] of the copolymer was measured at 135 ° C. in a decalin solvent using an Ubbelohde viscometer as a measuring device.
Specifically, about 20 mg of the powdery copolymer was dissolved in 25 ml of decalin, and then the specific viscosity ηsp was measured in an oil bath at 135 ° C. using an Ubbelohde viscometer. After 5 ml of decalin was added to the decalin solution for dilution, the specific viscosity ηsp was measured in the same manner as described above. This dilution operation was further repeated twice, and the value of ηsp / C when the concentration (C) was extrapolated to 0 was determined as the intrinsic viscosity [η] (unit: dl / g) (see the following formula 1).
[Η] = lim (ηsp / C) (C → 0) Equation 1

[Weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn)]
The weight average molecular weight (Mw) of the copolymer and the molecular weight distribution (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) are determined by gel permeation chromatography (GPC: Gel). It calculated by the standard polystyrene conversion method using Permeation Chromatography). The measurement conditions are as follows.

~conditions~
Measuring device: GPC (ALC / GPC 150-C plus type, suggested refractometer detector integrated type, manufactured by Waters)
Column: 2 GMH6-HT (manufactured by Tosoh Corp.) and 2 GMH6-HTL (manufactured by Tosoh Corp.) connected in series Eluent: o-dichlorobenzene Column temperature: 140 ° C
Flow rate: 1.0 mL / min

[Melt flow rate (MFR)]
The melt flow rate (MFR) of the copolymer was measured at 230 ° C. and a load of 2.16 kg in accordance with ASTM D1238. The unit is g / 10 min).

〔density〕
The density of the copolymer was measured according to JIS K7112 (density gradient tube method). This density (kg / m ³ ) was used as an indicator of lightness.

[Melting point (Tm)]
The melting point (Tm) of the copolymer was measured using a differential scanning calorimeter (DSC220C type, manufactured by Seiko Instruments Inc.) as a measuring device.
About 5 mg of the copolymer was sealed in a measurement aluminum pan and heated from room temperature to 200 ° C. at 10 ° C./min. In order to completely melt the copolymer, it was kept at 200 ° C. for 5 minutes and then cooled to −50 ° C. at 10 ° C./min. After 5 minutes at −50 ° C., the second heating was performed to 200 ° C. at 10 ° C./min. The peak temperature (° C.) at the second heating was defined as the melting point (Tm) of the copolymer. The melting point (Tm) of this copolymer was used as an index of heat resistance.

(Shock absorption)
The powdery copolymer obtained above was charged into a hopper of a 20 mmφ single screw extruder (single screw sheet forming machine, manufactured by Tanaka Iron Works Co., Ltd.) equipped with a T die having a lip width of 240 mm. The cylinder temperature was set to 100 ° C. to 250 ° C., the die temperature was set to 250 ° C., and the melt-kneaded product was extruded from the T die. The extruded melt-kneaded product was taken up at a chill roll temperature of 20 ° C. and a take-up speed of 10 m / min to obtain a cast film having a thickness of 50 μm. This cast film was cut out to 45 mm × 10 mm to obtain a test piece.
About this test piece, using a viscoelasticity measuring apparatus (MCR301, manufactured by Anton Paar), a dynamic viscoelasticity in a temperature range of −70 to 180 ° C. is measured at a frequency of 10 rad / s, and the glass transition temperature results. The maximum value (peak value) of the loss tangent (tan δ) and the temperature at which the maximum value was shown (temperature at the peak) were measured.

<Example 1A>
75 parts by mass of copolymer A-1A and a propylene-based polymer (Prime Polypro (registered trademark) F327, propylene / ethylene / butene random copolymer, density: 907 kg / m ³ , MFR (230 ° C.): 7 g / 10 min And 25 parts by mass (manufactured by Prime Polymer Co., Ltd.) were mixed (dry blended). Next, the obtained mixture was put into a hopper of a 20 mmφ single screw extruder (single screw sheet forming machine, manufactured by Tanaka Iron Works Co., Ltd.) equipped with a T die having a lip width of 240 mm. Then, the film of Example 1A was obtained by setting the cylinder temperature to 230 ° C. and the die temperature to 250 ° C., extruding the melt-kneaded material from the T-die and cast molding. The film had a thickness of 50 μm and a thickness of 200 μm.

<Example 2A>
Example 1A, except that 60 parts by mass of copolymer A-1A and 40 parts by mass of a propylene-based polymer (Prime Polypro (registered trademark) F327, manufactured by Prime Polymer Co., Ltd.) were mixed (dry blended). A film of Example 2A was obtained in the same manner as described above.

<Example 3A>
60 parts by mass of copolymer A-1A, propylene-based polymer (Prime Polypro (registered trademark) F107, propylene homopolymer, density: 910 kg / m ³ , MFR (230 ° C.): 7 g / 10 min, Prime Co., Ltd. A film of Example 3A was obtained by the same method as Example 1A, except that 40 parts by mass of polymer) was mixed (dry blended).

<Example 4A>
Example 1A, except that 60 parts by mass of copolymer A-2A and 40 parts by mass of a propylene-based polymer (Prime Polypro (registered trademark) F327, manufactured by Prime Polymer Co., Ltd.) were mixed (dry blended). The film of Example 4A was obtained by the same method as described above.

<Example 5A>
60 parts by mass of copolymer A-1A and ethylene polymer (Evolue (registered trademark) SP2540, linear low-density polyethylene, density: 924 kg / m ³ , MFR (190 ° C.): 3.8 g / 10 min, ( A film of Example 5A was obtained in the same manner as in Example 1A, except that 40 parts by mass of Prime Polymer Co., Ltd.) were mixed (dry blended).

<Comparative Example 1A>
Example 1A, except that 25 parts by mass of copolymer A-1A and 75 parts by mass of a propylene-based polymer (Prime Polypro (registered trademark) F327, manufactured by Prime Polymer Co., Ltd.) were mixed (dry blended). A film of Comparative Example 1A was obtained in the same manner as above.

<Comparative Example 2A>
Example 1A, except that 60 parts by mass of copolymer A-3A and 40 parts by mass of a propylene polymer (Prime Polypro (registered trademark) F327, manufactured by Prime Polymer Co., Ltd.) were mixed (dry blended). A film of Comparative Example 2A was obtained by the same method as described above.

<Comparative Example 3A>
A film of Comparative Example 3A was obtained by the same method as Example 1A, except that only an ethylene polymer (Evolue (registered trademark) SP2540, manufactured by Prime Polymer Co., Ltd.) was used as a raw material for the film.

<Comparative Example 4A>
A film of Comparative Example 4A was obtained by the same method as Example 1A, except that only a propylene polymer (Prime Polypro (registered trademark) F327, manufactured by Prime Polymer Co., Ltd.) was used as a raw material for the film. .

[Observation of film by transmission electron microscope (TEM)]
The films of Examples 1A to 5A and Comparative Examples 1A to 2A were ground with a microtome in the cross-sectional direction, and after trimming an ultrathin section of the film cross section, one was selectively exposed to ruthenium tetroxide vapor for a certain period of time. Were stained. The prepared sample was observed using a transmission electron microscope (TEM: Transmission Electron Microscope, model: H-7650) manufactured by Hitachi High-Tech Co., Ltd. under measurement conditions of acceleration voltage: 100 kV and observation magnification: 10,000 times. However, the film of Examples 1A to 5A and Comparative Examples 1A to 2A includes a sea part containing copolymer A-1A, copolymer A-2A, or copolymer A-3A, and a substantially propylene polymer. It was confirmed that it has a sea-island structure composed of A TEM image of the film of Example 2A is shown in FIG.

[Evaluation]
For the films of Examples 1A-5A and Comparative Examples 1A-4A, tensile yield strength (YS), tensile elongation at break (EL), tensile strength at break (TS), tensile modulus (YM), impact resistance, and stress The relaxation was evaluated. The evaluation results are shown in Table 2 below.

1. Tensile yield point strength, tensile elongation at break, tensile strength at break, and tensile modulus A film having a thickness of 200 μm cut into a dumbbell shape having a width of 25 mm and a length of 100 mm was used as a test piece.
In accordance with JIS K7127 (1999), using a tensile tester (universal tensile tester 3380, manufactured by Instron), the tension of the test piece was measured under the conditions of a distance between chucks of 50 mm, a tensile speed of 200 mm / min, and a temperature of 23 ° C. Yield point strength (unit: MPa), tensile breaking elongation (unit:%), tensile breaking strength (unit: MPa), and tensile modulus (unit: MPa) were measured.

2. Impact resistance A film having a thickness of 50 μm cut into a strip shape having a width of 100 mm and a length of 100 mm was used as a test piece.
Under the condition of 23 ° C., the test piece was sandwiched between metal chucks, and a cylindrical measuring jig having a tip diameter of 12.7 mm was dropped from a height of 50 cm obliquely. And the impact strength (fracture energy) to the test piece when contact was visually recognized by the test piece was measured, and the impact resistance of the film was evaluated according to the following evaluation criteria.
Those practically acceptable are those classified as [A].

(Evaluation criteria)
A: Breaking energy is 0.05 J or more.
B: Breaking energy is less than 0.05J.

3. Stress relaxation property A sheet having a thickness of 10 mm and a length of 100 mm punched out from a film having a thickness of 50 μm was used as a test piece.
Using a tensile tester (universal tensile tester 3380, manufactured by Instron), the test piece was stretched 10% under the conditions of a distance between chucks of 75 mm, a tensile speed of 200 mm / min, and a temperature of 23 ° C. And the stress (initial stress) at the time of extending | stretching 10% was measured, elongation of the test piece was hold | maintained as it was for 120 seconds, and the change of the stress in the meantime was also measured. Then, the stress relaxation rate was calculated from the difference between the initial stress and the stress 60 seconds after extension, and the stress relaxation property of the film was evaluated according to the following evaluation criteria.
Those practically acceptable are those classified into [A], [B] and [C].

(Evaluation criteria)
A: The stress relaxation rate is 60% or more.
B: The stress relaxation rate is 55% or more and less than 60%.
C: The stress relaxation rate is 52% or more and less than 55%.
D: Stress relaxation rate is less than 52%.

  As shown in Table 2, it can be seen that the films of Examples 1A to 5A have both impact resistance and stress relaxation properties. On the other hand, it can be seen that the films of Comparative Examples 1A, 3A, and 4A are inferior in stress relaxation, and the film of Comparative Example 2A is inferior in impact resistance.

<Example 6A>
75 parts by mass of copolymer A-1A, and ethylene polymer (Evolue (registered trademark) SP2540, linear low density polyethylene, density: 924 kg / m ³ , MFR (190 ° C.): 3.8 g / 10 min, A stress relaxation layer (thickness: 100 μm) made of a mixture obtained by mixing (dry blending) 25 parts by mass of Prime Polymer Co., Ltd., an ethylene polymer (Evolue (registered trademark) SP2540, Prime Co., Ltd.) A 20 mmφ single-screw extruder (with a T-die having a lip width of 200 mm) is formed from a laminate (thickness: 160 μm) composed of a surface layer (thickness: 30 μm) consisting of 100 parts by mass of a polymer) Using a uniaxial two-kind three-layer sheet molding machine (manufactured by Technobel Co., Ltd.), a two-kind three-layer film (stress relaxation layer in the middle) was formed by coextrusion. The cylinder temperature was set to 200 ° C., and the die temperature was set to 200 ° C.

<Example 7A>
In the same manner as in Example 6A, 75 parts by mass of copolymer A-1A and propylene-based polymer (prime polypro (registered trademark) F327, propylene / ethylene / butene random copolymer, density: 907 kg / m ³ , MFR (230 ° C.): 7 g / 10 min, manufactured by Prime Polymer Co., Ltd.) 25 parts by mass (dry blending) and a stress relaxation layer (thickness: 100 μm) composed of a mixture, and a propylene polymer ( A two-layer laminate (thickness: 130 μm) consisting of a surface layer (thickness: 30 μm) consisting of 100 parts by mass of Prime Polypro (registered trademark) F327, manufactured by Prime Polymer Co., Ltd. was molded.

<Example 8A>
In the same manner as in Example 6A, 75 parts by mass of copolymer A-1A and 25 parts by mass of an ethylene polymer (Evolue (registered trademark) SP2540, manufactured by Prime Polymer Co., Ltd.) were mixed (dry blended). A stress relaxation layer (thickness: 100 μm) made of the obtained mixture, 80 parts by mass of an ethylene copolymer (Evolue (registered trademark) SP2540, manufactured by Prime Polymer Co., Ltd.), and an ethylene polymer (Tuffmer (registered) Trademark) DF605, ethylene-butene copolymer (ratio of structural units derived from ethylene: 50 mol% or more, density: 861 kg / m ³ , MFR (230 ° C.): 0.9 g / 10 min, manufactured by Mitsui Chemicals, Inc. ) A laminate (thickness: 1) comprising a surface layer (thickness: 30 μm) composed of a mixture obtained by mixing (dry blending) 20 parts by mass. 30 μm).

<Example 9A>
In the same manner as in Example 6A, 75 parts by mass of copolymer A-2A and 25 parts by mass of a propylene-based polymer (Prime Polypro (registered trademark) F327, manufactured by Prime Polymer Co., Ltd.) were mixed (dry blended). And a surface layer (thickness: 30 μm) consisting of 100 parts by mass of a stress relaxation layer (thickness: 100 μm) made of the mixture and an ethylene polymer (Evolue (registered trademark) SP2540, manufactured by Prime Polymer Co., Ltd.). A laminate (thickness: 130 μm) having a two-layer structure was formed.

<Comparative Example 5A>
In the same manner as in Example 6A, a stress relaxation layer (thickness: 100 μm) composed of 100 parts by mass of an ethylene polymer (Evolue (registered trademark) SP2540, manufactured by Prime Polymer Co., Ltd.) and an ethylene polymer (Evolue) (Registered trademark) SP2540, manufactured by Prime Polymer Co., Ltd.) A two-layer laminate (thickness: 130 μm) consisting of a surface layer (thickness: 30 μm) consisting of 100 parts by mass was molded.

<Comparative Example 6A>
In the same manner as in Example 6A, a stress relaxation layer (thickness: 100 μm) composed of 100 parts by mass of a propylene polymer (Prime Polypro (registered trademark) F327, manufactured by Prime Polymer Co., Ltd.) and an ethylene polymer ( A layered product (thickness: 130 μm) composed of a surface layer (thickness: 30 μm) composed of 100 parts by mass of Evolue (registered trademark) SP2540, manufactured by Prime Polymer Co., Ltd. was molded.

<Comparative Example 7A>
In the same manner as in Example 6A, a stress relaxation layer (thickness: 100 μm) consisting of 100 parts by mass of copolymer A-1A and an ethylene polymer (Evolue (registered trademark) SP2540, manufactured by Prime Polymer Co., Ltd.) A two-layer laminate (thickness: 130 μm) composed of a surface layer (thickness: 30 μm) composed of 100 parts by mass was molded.

[Evaluation]
For the laminates of Examples 6A to 9A and Comparative Examples 5A to 7A, tensile yield strength (YS), tensile elongation at break (EL), tensile strength at break (TS), tensile modulus (YM), impact resistance, stress The relaxation properties and peel strength were evaluated. The evaluation results are shown in Table 3 below.

1. Tensile yield point strength, tensile elongation at break, tensile strength at break, and tensile modulus The laminate was cut into a dumbbell shape having a width of 25 mm and a length of 100 mm was used as a test piece.
In accordance with JIS K7127 (1999), using a tensile tester (universal tensile tester 3380, manufactured by Instron), the tension of the test piece was measured under the conditions of a distance between chucks of 50 mm, a tensile speed of 200 mm / min, and a temperature of 23 ° C. Yield point strength (unit: MPa), tensile breaking elongation (unit:%), tensile breaking strength (unit: MPa), and tensile modulus (unit: MPa) were measured.

2. Impact resistance A laminate obtained by cutting a laminate into a strip shape having a width of 100 mm and a length of 100 mm was used as a test piece.
Under the condition of 23 ° C., the test piece was sandwiched between metal chucks, and a cylindrical measuring jig having a tip diameter of 12.7 mm was dropped from a height of 50 cm obliquely. And the impact strength (fracture energy) to the test piece when contact was visually recognized by the test piece was measured, and the impact resistance of the laminate was evaluated according to the following evaluation criteria.
Those practically acceptable are those classified as [A].

(Evaluation criteria)
A: Breaking energy is 0.05 J or more.
B: Breaking energy is less than 0.05J.

3. Stress relaxation property A sheet having a width of 10 mm and a length of 100 mm punched from the laminate was used as a test piece.
Using a tensile tester (universal tensile tester 3380, manufactured by Instron), the test piece was stretched 10% under the conditions of a distance between chucks of 75 mm, a tensile speed of 200 mm / min, and a temperature of 23 ° C. And the stress (initial stress) at the time of extending | stretching 10% was measured, elongation of the test piece was hold | maintained as it was for 120 seconds, and the change of the stress in the meantime was also measured. And the stress relaxation rate was computed from the difference of the said initial stress and the stress 60 second after extension, and the stress relaxation property of the laminated body was evaluated according to the following evaluation criteria.
Those practically acceptable are those classified into [A], [B] and [C].

(Evaluation criteria)
A: The stress relaxation rate is 60% or more.
B: The stress relaxation rate is 55% or more and less than 60%.
C: The stress relaxation rate is 52% or more and less than 55%.
D: Stress relaxation rate is less than 52%.

4). Peeling strength The laminate was cut into strips having a width of 15 mm and a length of 100 mm, and used as a test piece.
As a measuring device, a tensile tester (universal tensile tester 3380, manufactured by Instron) was used, and the adhesion surface between the stress relaxation layer and the surface layer was obtained under the conditions of a distance between chucks of 80 mm, a tensile speed of 200 mm / min, and a temperature of 23 ° C. The film was pulled in the direction of 180 ° to peel off the stress relaxation layer and the surface layer. The measured values of the five test pieces were averaged to obtain the peel strength.

  As shown in Table 3, it can be seen that the laminates of Examples 6A to 9A have both impact resistance and stress relaxation properties. Moreover, in the laminated body of Example 6A-9A, it turns out that the peeling strength between the layers of a stress relaxation layer and a surface layer is high, and the adhesiveness of a stress relaxation layer and a surface layer is favorable. On the other hand, the laminates of Comparative Examples 5A and 6A are inferior in stress relaxation properties, and the laminate of Comparative Example 7A has low peel strength between the stress relaxation layer and the surface layer, and is easily peeled off. .

<< Example of the second aspect >>
[Synthesis Example 1B] Synthesis of Copolymer A-1B Into a SUS autoclave with a 1.5 L stirring blade sufficiently purged with nitrogen, 300 ml of n-hexane (dried on activated alumina in a dry nitrogen atmosphere) ), And 450 ml of 4-methyl-1-pentene were charged at 23 ° C., then, 0.75 ml of a 1.0 mmol / ml toluene solution of triisobutylaluminum (TIBAL) was charged, and the stirrer was rotated.
Next, the autoclave was heated until the internal temperature reached 60 ° C., and pressurized with propylene so that the total pressure (gauge pressure) was 0.19 MPa.
Subsequently, 1 mmol of methylaluminoxane and 0.01 mmol of diphenylmethylene (1-ethyl-3-t-butyl-cyclopentadienyl) (2,7-di-t-) prepared in advance were converted into Al. 0.34 ml of a toluene solution containing (butyl-fluorenyl) zirconium dichloride was pressed into the autoclave with nitrogen to initiate the polymerization reaction. During the polymerization reaction, the temperature was adjusted so that the internal temperature of the autoclave was 60 ° C.
Sixty minutes after the start of the polymerization, 5 ml of methanol was pressed into the autoclave with nitrogen to stop the polymerization reaction, and then the inside of the autoclave was depressurized to the atmospheric pressure. After depressurization, acetone was added to the reaction solution while stirring the reaction solution to obtain a polymerization reaction product containing a solvent. Subsequently, the polymerization reaction product containing the obtained solvent was dried at 130 ° C. under reduced pressure for 12 hours to obtain 44.0 g of a powdery copolymer A-1B.

Table 4 shows the measurement results of various physical properties of the obtained copolymer A-1B.
The content of 4-methyl-1-pentene in the copolymer A-1B was 84.1 mol%, and the content of propylene was 15.9 mol%. Further, the density of the copolymer A-1B was 838 kg / m ³ . Copolymer A-1B has an intrinsic viscosity [η] of 1.5 dl / g, a weight average molecular weight (Mw) of 340,000, a molecular weight distribution (Mw / Mn) of 2.1, and a melt flow The rate (MFR) was 11 g / 10 min. The melting point (Tm) of the copolymer A-1B was 132 ° C., and the maximum value of tan δ was 1.6 (temperature when showing the maximum value: 39 ° C.).

[Synthesis Example 2B] Synthesis of Copolymer A-2B To a SUS autoclave with a 1.5-liter stirring blade sufficiently purged with nitrogen, 300 ml of n-hexane (dried on activated alumina in a dry nitrogen atmosphere) ), And 450 ml of 4-methyl-1-pentene were charged at 23 ° C., then, 0.75 ml of a 1.0 mmol / ml toluene solution of triisobutylaluminum (TIBAL) was charged, and the stirrer was rotated.
Next, the autoclave was heated to an internal temperature of 60 ° C. and pressurized with propylene so that the total pressure (gauge pressure) was 0.40 MPa.
Subsequently, 1 mmol of methylaluminoxane and 0.01 mmol of diphenylmethylene (1-ethyl-3-t-butyl-cyclopentadienyl) (2,7-di-t-) prepared in advance were converted into Al. 0.34 ml of a toluene solution containing (butyl-fluorenyl) zirconium dichloride was pressed into the autoclave with nitrogen to initiate the polymerization reaction. During the polymerization reaction, the temperature was adjusted so that the internal temperature of the autoclave was 60 ° C.
Sixty minutes after the start of the polymerization, 5 ml of methanol was pressed into the autoclave with nitrogen to stop the polymerization reaction, and then the inside of the autoclave was depressurized to the atmospheric pressure. After depressurization, acetone was added to the reaction solution while stirring the reaction solution to obtain a polymerization reaction product containing a solvent. Subsequently, the polymerization reaction product containing the obtained solvent was dried at 130 ° C. under reduced pressure for 12 hours to obtain 36.9 g of a powdery copolymer A-2B.

Table 4 shows the measurement results of various physical properties of the obtained copolymer A-2B.
The content of 4-methyl-1-pentene in copolymer A-2B was 72.5 mol%, and the content of propylene was 27.5 mol%. Further, the density of the copolymer A-2B was 839 kg / m ³ . Copolymer A-2B has an intrinsic viscosity [η] of 1.5 dl / g, a weight average molecular weight (Mw) of 337,000, a molecular weight distribution (Mw / Mn) of 2.1, and a melt flow The rate (MFR) was 11 g / 10 min. The melting point (Tm) of the copolymer A-2B was not observed, and the maximum value of tan δ was 2.8 (temperature when showing the maximum value: 31 ° C.).

  Methods for measuring various physical properties of the copolymers A-1B and A-2B are shown below.

〔composition〕
The content (mol%) of 4-methyl-1-pentene and propylene (C3 α-olefin) in the copolymer was measured by ¹³ C-NMR. The measurement conditions are as follows.

~conditions~
Measuring apparatus: Nuclear magnetic resonance apparatus (ECP500 type, manufactured by JEOL Ltd.)
Observation nucleus: ¹³ C (125 MHz)
Sequence: Single pulse proton decoupling Pulse width: 4.7 μsec (45 ° pulse)
Repeat time: 5.5 seconds Accumulated number: 10,000 times or more Solvent: Orthodichlorobenzene / deuterated benzene (volume ratio: 80/20) mixed solvent Sample concentration: 55 mg / 0.6 mL
Measurement temperature: 120 ° C
Standard value of chemical shift: 27.50ppm

[Intrinsic viscosity [η]]
The intrinsic viscosity [η] of the copolymer was measured at 135 ° C. in a decalin solvent using an Ubbelohde viscometer as a measuring device.
Specifically, about 20 mg of the powdery copolymer was dissolved in 25 ml of decalin, and then the specific viscosity ηsp was measured in an oil bath at 135 ° C. using an Ubbelohde viscometer. After 5 ml of decalin was added to the decalin solution for dilution, the specific viscosity ηsp was measured in the same manner as described above. This dilution operation was further repeated twice, and the value of ηsp / C when the concentration (C) was extrapolated to 0 was determined as the intrinsic viscosity [η] (unit: dl / g) (see the following formula 1).
[Η] = lim (ηsp / C) (C → 0) Equation 1

[Weight average molecular weight (Mw) and molecular weight distribution (Mw / Mn)]
The weight average molecular weight (Mw) of the copolymer and the molecular weight distribution (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) are determined by gel permeation chromatography (GPC: Gel). It calculated by the standard polystyrene conversion method using Permeation Chromatography). The measurement conditions are as follows.

~conditions~
Measuring device: GPC (ALC / GPC 150-C plus type, suggested refractometer detector integrated type, manufactured by Waters)
Column: 2 GMH6-HT (manufactured by Tosoh Corp.) and 2 GMH6-HTL (manufactured by Tosoh Corp.) connected in series Eluent: o-dichlorobenzene Column temperature: 140 ° C
Flow rate: 1.0 mL / min

[Melt flow rate (MFR)]
The melt flow rate (MFR) of the copolymer was measured at 230 ° C. and a load of 2.16 kg in accordance with ASTM D1238. The unit is g / 10 min).

〔density〕
The density of the copolymer was measured according to JIS K7112 (density gradient tube method). This density (kg / m ³ ) was used as an indicator of lightness.

[Melting point (Tm)]
The melting point (Tm) of the copolymer was measured using a differential scanning calorimeter (DSC220C type, manufactured by Seiko Instruments Inc.) as a measuring device.
About 5 mg of the copolymer was sealed in a measurement aluminum pan and heated from room temperature to 200 ° C. at 10 ° C./min. In order to completely melt the copolymer, it was kept at 200 ° C. for 5 minutes and then cooled to −50 ° C. at 10 ° C./min. After 5 minutes at −50 ° C., the second heating was performed to 200 ° C. at 10 ° C./min. The peak temperature (° C.) at the second heating was defined as the melting point (Tm) of the copolymer. The melting point (Tm) of this copolymer was used as an index of heat resistance.

(Shock absorption)
The powdery copolymer obtained above was charged into a hopper of a 20 mmφ single screw extruder (single screw sheet forming machine, manufactured by Tanaka Iron Works Co., Ltd.) equipped with a T die having a lip width of 240 mm. The cylinder temperature was set to 100 ° C. to 250 ° C., the die temperature was set to 250 ° C., and the melt-kneaded product was extruded from the T die. The extruded melt-kneaded product was taken up at a chill roll temperature of 20 ° C. and a take-up speed of 10 m / min to obtain a cast film having a thickness of 50 μm. This cast film was cut out to 45 mm × 10 mm to obtain a test piece.
About this test piece, the dynamic viscoelasticity of the temperature range of -70-180 degreeC was measured with the frequency of 10 rad / s using the viscoelasticity measuring apparatus (MCR301, product made by Anton Paar). Then, the maximum value of the loss tangent (tan δ) due to the obtained glass transition temperature and the temperature at which the maximum value was shown were used as an index of shock absorption.

[Stress relaxation film]
<Example 1B>
30 parts by mass of copolymer A-1B and an ethylene polymer (Evolue (registered trademark) SP2540, linear low density polyethylene, density: 924 kg / m ³ , MFR (190 ° C.): 3.8 g / 10 min, ( 70 parts by mass (manufactured by Prime Polymer Co., Ltd.) were mixed (dry blended). Next, the obtained mixture was put into a hopper of a 20 mmφ single screw extruder (single screw sheet forming machine, manufactured by Tanaka Iron Works Co., Ltd.) equipped with a T die having a lip width of 240 mm. The cylinder temperature was set to 230 ° C., the die temperature was set to 250 ° C., the melt-kneaded product was extruded from the T die, and cast to obtain a stress relaxation film (thickness: 200 μm).

<Example 2B>
40 parts by mass of copolymer A-1B and a propylene polymer (Prime Polypro (registered trademark) F327, propylene / ethylene / butene random copolymer, density: 907 kg / m ³ , MFR (230 ° C.): 7 g / 10 min Except that 60 parts by mass (manufactured by Prime Polymer Co., Ltd.) were mixed (dry blended), a stress relaxation film (thickness: 200 μm) was obtained in the same manner as in Example 1B.

<Example 3B>
Example 1B except that 20 parts by mass of copolymer A-2B and 80 parts by mass of an ethylene-based polymer (Evolue (registered trademark) SP2540, manufactured by Prime Polymer Co., Ltd.) were mixed (dry blended). A stress relaxation film (thickness: 200 μm) was obtained by the same method.

<Comparative Example 1B>
As raw materials, 50 parts by mass of an ethylene polymer (Evolue (registered trademark) SP2540, manufactured by Prime Polymer Co., Ltd.) and an ethylene polymer (Evolue (registered trademark) SP0540, linear low-density polyethylene, density: 903 kg / Example 3B except that only a mixture obtained by mixing (dry blending) m ³ , MFR (190 ° C.): 3.8 g / 10 min, manufactured by Prime Polymer Co., Ltd. (50 parts by mass) was used. By the same method, a stress relaxation film (thickness: 200 μm) was obtained.

<Comparative Example 2B>
A stress relieving film (thickness: 200 μm) was produced in the same manner as in Example 1B except that only a propylene polymer (Prime Polypro (registered trademark) F327, manufactured by Prime Polymer Co., Ltd.) was used as a raw material. Obtained.

<Comparative Example 3B>
A stress relaxation film (thickness: 200 μm) was obtained by the same method as in Example 1B, except that only copolymer A-1B was used as a raw material.

[Observation of film by transmission electron microscope (TEM)]
The stress-relaxing films of Examples 1B to 3B were ground with a microtome in the cross-sectional direction to trim an ultrathin section of the film cross section, and then exposed to ruthenium tetroxide vapor for a certain period of time to selectively stain one of them. . When the produced sample was observed using a transmission electron microscope (TEM: Transmission Electron Microscope, model: H-7650) manufactured by Hitachi High-Technology Co., Ltd. under measurement conditions of acceleration voltage: 100 kV and observation magnification: 3000 times. The stress relaxation film of Example 1B has a sea-island structure composed of an island part containing the copolymer A-1B and a sea part substantially made of an ethylene polymer, and Example 2B. The stress relaxation film of Example 3B has a sea-island structure composed of an island part containing the copolymer A-1B and a sea part substantially consisting of a propylene-based polymer. It was confirmed that the film has a sea-island structure composed of an island part containing the copolymer A-2B and a sea part substantially made of an ethylene polymer. A TEM image of the film of Example 3B is shown in FIG.

[Measurement of stress relaxation rate]
From the stress relaxation films of Examples 1B to 3B and Comparative Examples 1B to 3B, a sheet having a width of 10 mm and a length of 100 mm punched out was used as a test piece.
Using a tensile tester (universal tensile tester 3380, manufactured by Instron), the test piece was stretched 10% under the conditions of a distance between chucks of 75 mm, a tensile speed of 200 mm / min, and a temperature of 23 ° C. And the stress (initial stress) at the time of extending | stretching 10% was measured, elongation of the test piece was hold | maintained as it was for 120 seconds, and the change of the stress in the meantime was also measured. Then, the stress relaxation rate (unit:%) was calculated from the difference between the initial stress and the stress 60 seconds after elongation, and used as an index for evaluating stress relaxation. The results are shown in Table 5 below.

[Laminate]
<Example 4B>
Stress relaxation layer comprising a mixture obtained by mixing (dry blending) 30 parts by mass of copolymer A-1B and 70 parts by mass of an ethylene polymer (Evolue (registered trademark) SP2540, manufactured by Prime Polymer Co., Ltd.). (Thickness: 100 μm) and a surface layer (thickness: 30 μm each) consisting of 100 parts by mass of an ethylene polymer (Evolue (registered trademark) SP2540, manufactured by Prime Polymer Co., Ltd.) A 20 mmφ single screw extruder (manufactured by Technobel Co., Ltd.) having a laminated body (thickness: 160 μm, layer structure: surface layer / stress relaxation layer / surface layer) provided with a two-type three-layer T-die having a lip width of 200 mm. ) And was formed by coextrusion. The cylinder temperature was set to 200 ° C., and the die temperature was set to 200 ° C.

<Example 5B>
In the same manner as in Example 4B, 40 parts by mass of copolymer A-1B and 60 parts by mass of a propylene-based polymer (Prime Polypro (registered trademark) F327, manufactured by Prime Polymer Co., Ltd.) were mixed (dry blended). A stress relaxation layer (thickness: 100 μm) made of the obtained mixture and a surface layer (thickness: each) consisting of 100 parts by mass of a propylene polymer (Prime Polypro (registered trademark) F327, manufactured by Prime Polymer Co., Ltd.) 30 μm) and a laminated body having a two-layer / three-layer structure (thickness: 160 μm, layer structure: surface layer / stress relaxation layer / surface layer).

<Example 6B>
In the same manner as in Example 4B, 30 parts by mass of copolymer A-2B and 70 parts by mass of an ethylene-based polymer (Evolue (registered trademark) SP2540, manufactured by Prime Polymer Co., Ltd.) were mixed (dry blended). A stress relaxation layer (thickness: 100 μm) made of the obtained mixture, 80 parts by mass of an ethylene copolymer (Evolue (registered trademark) SP2540, manufactured by Prime Polymer Co., Ltd.), and an ethylene polymer (Tuffmer (registered) Trademark) DF605, ethylene-butene copolymer (ratio of structural units derived from ethylene: 50 mol% or more, density: 861 kg / m ³ , MFR (230 ° C.): 0.9 g / 10 min, manufactured by Mitsui Chemicals, Inc. ) A laminate (thickness) of a two-layer / three-layer structure composed of a surface layer (thickness: 30 μm each) composed of a mixture obtained by mixing (dry blending) 20 parts by mass. S: 160 μm, layer structure: surface layer / stress relaxation layer / surface layer).

<Comparative Example 4B>
In the same manner as in Example 4B, 50 parts by mass of an ethylene polymer (Evolue (registered trademark) SP2540, manufactured by Prime Polymer Co., Ltd.) and an ethylene polymer (Evolue (registered trademark) SP0540, Prime Polymer Co., Ltd.) were used. Made by mixing (dry blending) 50 parts by mass, a stress relaxation layer (thickness: 100 μm) made of a mixture, and an ethylene polymer (Evolue (registered trademark) SP2540, manufactured by Prime Polymer Co., Ltd.) ) A layered body (thickness: 160 μm, layer structure: surface layer / stress relaxation layer / surface layer) composed of a surface layer (thickness: 30 μm each) consisting of 100 parts by mass and two kinds and three layers.

<Comparative Example 5B>
In the same manner as in Example 4B, a stress relaxation layer (thickness: 100 μm) composed of 100 parts by mass of a propylene polymer (Prime Polypro (registered trademark) F327, manufactured by Prime Polymer Co., Ltd.) and an ethylene polymer ( Evolue (registered trademark) SP2540, manufactured by Prime Polymer Co., Ltd., a surface layer (thickness: 30 μm each) composed of 100 parts by mass, and a laminate of two types and three layers (thickness: 160 μm, layer configuration: surface) Layer / stress relaxation layer / surface layer).

<Comparative Example 6B>
In the same manner as in Example 4B, a stress relaxation layer (thickness: 100 μm) consisting of 100 parts by mass of copolymer A-1B and an ethylene-based polymer (Evolue (registered trademark) SP2540, manufactured by Prime Polymer Co., Ltd.) A surface layer composed of 100 parts by mass (thickness: 30 μm each) and a laminate of two types and three layers composed of (thickness: 160 μm, layer configuration: surface layer / stress relaxation layer / surface layer) were formed.

(Measurement of peel strength)
What cut | disconnected the laminated body of Example 4B-6B and Comparative Example 4B-6B in strip shape of width 15mm x length 100mm was used as a test piece.
After scratching the surface (one surface) of the test piece using a cutter, a strong adhesive tape is applied to both ends of the test piece, and the strong adhesive tape is pulled by hand to obtain a surface layer and a stress relaxation layer. Attempts were made to peel the gaps. At this time, the laminate that was not peeled was described as “not peeled” in the corresponding column of Table 5 below. Regarding the peeled laminate, a stress relaxation layer and a surface were separately used with a tensile tester (universal tensile tester 3380, manufactured by Instron) under the conditions of a distance between chucks of 80 mm, a tensile speed of 300 mm / min, and a temperature of 23 ° C. The layer was pulled in the direction of 180 ° with respect to the adhesive surface with the layer, the stress relaxation layer and the surface layer were peeled, and the peel strength (interlayer peel strength) was measured. The peel strength was measured for five test pieces and the average value was calculated. The results are shown in Table 5 below.

  As shown in Table 5, the stress relaxation film of the present invention has good stress relaxation properties (see Examples 1B to 3B), and when laminated with other layers, Good adhesiveness was exhibited (see Examples 4B to 6B).

  The stress relieving film of the present invention is a surface protective film used for the purpose of preventing scratches during transportation, storage and processing of various resin products such as building materials and optical parts, metal products, glass products, and dust prevention purposes. Or it is useful as the member. Moreover, when the stress relaxation film of the present invention is used as a film for protecting the circuit formation surface during grinding of the semiconductor substrate, it is possible to prevent the semiconductor substrate from being cracked or scratched. Therefore, the stress relaxation film of the present invention is very useful as a surface protective film for a semiconductor substrate or a member thereof.

The disclosures of Japanese application 2013-137495, Japanese application 2013-163579, and Japanese application 2013-173556 are incorporated herein by reference in their entirety.
All documents, patent applications, and technical standards described in this specification are specifically and individually incorporated by reference as if individual documents, patent applications, and technical standards were incorporated by reference. To the extent it is incorporated herein by reference.

Claims (12)

A structural unit derived from 4-methyl-1-pentene is contained in an amount of 70 mol% to 90 mol%, and a structural unit derived from an α-olefin having 2 or 3 carbon atoms; A thermoplastic resin A which is a copolymer having a proportion of structural units derived from an α-olefin having 4 to 20 carbon atoms other than methyl-1-pentene of 10 mol% or less;
Thermoplastics other than the thermoplastic resin A, which is at least one polymer selected from the group consisting of ethylene polymers, propylene polymers, butene polymers, and 4-methyl-1-pentene polymers. Resin B,
The content of the thermoplastic resin A is 50% by mass to 98% by mass with respect to the total mass,
A stress relaxation layer comprising a stress relaxation film, wherein the content of the thermoplastic resin B is 2% by mass to 50% by mass with respect to the total mass ;
A thermoplastic resin C that is at least one polymer selected from the group consisting of an ethylene polymer, a propylene polymer, and a butene polymer, and at least a part of the thermoplastic resin C is in contact with the stress relaxation layer. A surface layer,
A laminate comprising The laminate according to claim 1, wherein the thermoplastic resin A is a copolymer containing 75 mol% to 88 mol% of a structural unit derived from 4-methyl-1-pentene. The laminate according to claim 1 or claim 2, wherein the thermoplastic resin B is at least one polymer selected from the group consisting of an ethylene polymer and a propylene polymer. The said stress relaxation film has the sea-island structure comprised from the sea part which contains the said thermoplastic resin A, and the island part which consists of the said thermoplastic resin B substantially, The claim 1 or Claim 2 The laminated body of description. A structural unit derived from 4-methyl-1-pentene is contained in an amount of 70 mol% to 90 mol%, and a structural unit derived from an α-olefin having 2 or 3 carbon atoms; A thermoplastic resin A which is a copolymer having a proportion of structural units derived from an α-olefin having 4 to 20 carbon atoms other than methyl-1-pentene of 10 mol% or less;
Thermoplastics other than the thermoplastic resin A, which is at least one polymer selected from the group consisting of ethylene polymers, propylene polymers, butene polymers, and 4-methyl-1-pentene polymers. Resin B,
The content of the thermoplastic resin A is 50% by mass to 98% by mass with respect to the total mass,
A stress relaxation film in which the content of the thermoplastic resin B is 2% by mass to 50% by mass with respect to the total mass;
A base material layer having a storage elastic modulus G ′ (25) at 25 ° C. measured at a frequency of 1.6 Hz of 5 × 10 ⁷ Pa or more;
A surface protective film for a semiconductor that protects a circuit forming surface of the semiconductor substrate when the semiconductor substrate is ground. The surface protective film for a semiconductor according to claim 5 , comprising an adhesive layer on the side opposite to the side on which the base material layer of the stress relaxation film is present. A structural unit derived from 4-methyl-1-pentene is contained in an amount of 70 mol% to 90 mol%, and a structural unit derived from an α-olefin having 2 or 3 carbon atoms; A thermoplastic resin A which is a copolymer having a proportion of structural units derived from an α-olefin having 4 to 20 carbon atoms other than methyl-1-pentene of 10 mol% or less;
Thermoplastics other than the thermoplastic resin A, which is at least one polymer selected from the group consisting of ethylene polymers, propylene polymers, butene polymers, and 4-methyl-1-pentene polymers. Resin B,
The content of the thermoplastic resin A is 2% by mass or more and less than 50% by mass with respect to the total mass,
A stress relaxation layer comprising a stress relaxation film, wherein the content of the thermoplastic resin B is 50% by mass or more and 98% by mass or less with respect to the total mass ;
A thermoplastic resin C that is at least one polymer selected from the group consisting of an ethylene polymer, a propylene polymer, and a butene polymer, and at least a part of the thermoplastic resin C is in contact with the stress relaxation layer. A surface layer,
A laminate comprising The laminate according to claim 7 , wherein the thermoplastic resin A is a copolymer containing 70 mol% to 88 mol% of a structural unit derived from 4-methyl-1-pentene. The laminate according to claim 7 or 8 , wherein the thermoplastic resin B is at least one polymer selected from the group consisting of ethylene polymers and propylene polymers. The said stress relaxation film has a sea island structure comprised from the island part which comprises the said thermoplastic resin A, and the sea part which consists of the said thermoplastic resin B substantially, The claim 7 or Claim 8 The laminated body of description. A structural unit derived from 4-methyl-1-pentene is contained in an amount of 70 mol% to 90 mol%, and a structural unit derived from an α-olefin having 2 or 3 carbon atoms; A thermoplastic resin A which is a copolymer having a proportion of structural units derived from an α-olefin having 4 to 20 carbon atoms other than methyl-1-pentene of 10 mol% or less;
Thermoplastics other than the thermoplastic resin A, which is at least one polymer selected from the group consisting of ethylene polymers, propylene polymers, butene polymers, and 4-methyl-1-pentene polymers. Resin B,
The content of the thermoplastic resin A is 2% by mass or more and less than 50% by mass with respect to the total mass,
A stress relaxation film, wherein the content of the thermoplastic resin B is 50% by mass or more and 98% by mass or less with respect to the total mass;
A base material layer having a storage elastic modulus G ′ (25) at 25 ° C. measured at a frequency of 1.6 Hz of 5 × 10 ⁷ Pa or more;
A surface protective film for a semiconductor that protects a circuit forming surface of the semiconductor substrate when the semiconductor substrate is ground. The surface protection film for a semiconductor according to claim 11 , comprising an adhesive layer on the side opposite to the side on which the base material layer of the stress relaxation film is present.