JP5687022B2 - Surface protection film - Google Patents

Description

  The present invention relates to a surface protective film used for optical products, building materials, automobile parts and the like. Specifically, it has excellent adhesive properties, particularly adhesiveness to adherends and stability over time of adhesive strength, excellent heat resistance, less contamination to adherends, etc., and excellent appearance such as fish eyes, The present invention relates to a surface protective film that does not damage an adherend and that is easy to feed out from a roll.

  The surface protection film is mainly used by adhering to adherends such as resin products, metal products, and glass products for building materials and optical applications. Plays. These surface protective films generally comprise a non-adhesive surface layer and an adhesive layer for adhering to the adherend. The surface layer is usually formed from a polyolefin such as polyethylene or polypropylene, a polyester such as polyethylene terephthalate, or a vinyl polymer such as polyvinyl chloride.

  In recent years, development of members used for liquid crystal screens, plasma displays (PDP), rear projection screens, and so on, so-called optical products, has been progressing. The surface protective film for protecting these optical products is not only scratched or contaminated with foreign matter, but also transparent so that product inspection can be performed with the surface protective film attached, and pasting and heat treatment processes at high temperatures. In addition, characteristics such as appropriate adhesive strength are desired.

  For optical products, there are many members that require optical properties, such as polarizing plates, retardation plates, light guide plates, and prism plates, and these members are also stable with appropriate adhesive strength and time. A protective film capable of exhibiting adhesive strength is desired.

  On the other hand, when a surface protective film is used for these optical members, when the surface protective film is peeled off, if the adhesive residue or fish eyes are present on the surface protective film, the optical member may be defective. There is a demand for a surface protective film free of fish and fish eyes.

  In addition, since a surface protective film having a relatively high adhesive strength is difficult to be fed out from a roll-shaped product, it is formed into a roll shape with a release film bonded to an adhesive layer, and applied to an adherend. The release film is peeled off and used. When such a process is employed, a large amount of waste is generated, and thus a surface protective film that can be easily fed out from a roll without a release film is required.

  Japanese Unexamined Patent Application Publication No. 2006-116769 discloses a surface protective film mainly composed of a polyethylene component. However, although the method according to the publication can be applied to some use members, the adhesive strength is low and the transparency is insufficient, and the use of the adherend is limited.

  JP 2009-83110 A proposes a surface protective film made of a specific propylene random block copolymer obtained by a metallocene catalyst system. However, the method disclosed in this publication has low adhesive strength, and further improvement is desired.

JP 2006-116769 A JP 2009-83110 A

  The present invention has characteristics required as a surface protective film for protecting optical products, building material products and automobile parts during storage, transportation, processing, inspection, in particular, adhesive properties to adherends, transparency and heat resistance. The object is to provide a surface protective film that is excellent in appearance, has little contamination on the adherend, has excellent appearance such as fish eyes, does not damage the adherend, and has excellent roll-out performance. .

  As a result of intensive studies in view of the above problems, the present inventors have found that the above problems can be solved by a surface protective film having an adhesive layer made of a specific resin composition, and have completed the present invention.

That is, the present invention is a surface protective film comprising at least two layers of a surface layer (A) and an adhesive layer (X), the surface layer (A) is made of a polyolefin resin, and the adhesive layer (X) uses a metallocene catalyst. 10 to 90% by weight of a low crystalline α-olefin (co) polymer (X-1) having a tensile modulus of 100 to 400 MPa as a main component and an α-olefin having 3 or more carbon atoms obtained as a main component, and The α-olefin (co) polymer (X-2) obtained by using a metallocene catalyst has a tensile modulus of less than 100 MPa, and is 90 to 10% by weight ((X-1) and (X-2) in total 100). It is related with the surface protection film characterized by being formed from the composition which consists of weight%.

  Moreover, according to the suitable aspect of this invention, the low crystalline alpha-olefin (co) polymer (X-1) which comprises the composition of the said adhesion layer (X) is propylene, and C2-C10. It is desirable to use a copolymer with an α-olefin (excluding propylene).

Furthermore, according to a preferred aspect of the present invention, it is desirable that the low crystalline α-olefin (co) polymer (X-1) is a reactor TPO obtained with a metallocene catalyst.
Furthermore, according to a preferred aspect of the present invention, it is desirable to form a multilayer film obtained by extruding at least two layers of the surface layer (A) and the adhesive layer (X) from a T-die.

  The “(co) polymer” is a collective term for a homopolymer having only one type of monomer constituting the polymer and a copolymer having two or more types.

  The surface protective film of the present invention is excellent in adhesive properties and stability over time, transparency, unwinding force and heat resistance, and has a very high industrial utility value as a protective film for optical use, building material use and automotive part use.

Next, the present invention will be described in detail.
The surface protective film of the present invention comprises at least two layers of the surface layer (A) and the adhesive layer (X), or at least 3 of the surface layer (A), the substrate layer (B) and the adhesive layer (X) as necessary. Consists of layers. Here, when the adhesive layer (X) is the innermost layer, the surface layer (A) is located in the outermost layer, and when the film is rolled, the surface layer (A) and the adhesive layer (X) are in contact with each other. To do.
The surface layer (A) is made of a polyolefin resin.

  Examples of the polyolefin resin include known polyolefin resins such as polypropylene and polyethylene. As polypropylene, homopolypropylene, random polypropylene composed of propylene and ethylene, block polypropylene containing propylene / ethylene copolymer component or propylene / 1-butene / ethylene copolymer component, etc., high pressure method low density polyethylene as polyethylene And linear low density polyethylene and high density polyethylene. Among these, high pressure method low density polyethylene is preferable from the viewpoint of unwinding, and homopolypropylene and block polypropylene are preferably used from the viewpoint of transparency and heat resistance.

  In the composition for forming the surface layer (A), an antistatic agent, a release agent, an antioxidant, a weathering agent, a crystal nucleating agent, etc., as long as the properties as the surface protective film of the present invention are not impaired. It is also possible to add various additives and other resin modifiers such as polyolefin resin, wax, polyester, polyamide, and elastomer.

The pressure-sensitive adhesive layer (X) of the surface protective film of the present invention has a low crystalline α- having a tensile elastic modulus in the range of 100 MPa to 400 MPa as a main component of an α-olefin having 3 or more carbon atoms obtained using a metallocene catalyst. Olefin (co) polymer (X-1) 10 to 90% by weight, preferably 35 to 85% by weight, and a propylene (co) polymer (X) having a tensile modulus of less than 100 MPa and obtained using a metallocene catalyst (X -2) The total of the compositions (X-1) and (X-2) comprising 90 to 10% by weight, preferably 65 to 15% by weight, is 100% by weight. ).

  The low crystalline α-olefin (co) polymer (X-1) is a low crystalline α-olefin (co) polymer having a tensile modulus measured by JISK7161 in the range of 100 to 400 MPa. The tensile modulus is preferably in the range of 120 to 350 MPa, more preferably in the range of 130 to 300 MPa. Preferred forms of the low crystalline α-olefin (co) polymer (X-1) are propylene and at least one α-olefin having 2 to 20 carbon atoms, preferably 2 to 10 carbon atoms (excluding propylene). Is a low-crystalline α-olefin (co) polymer obtained by copolymerizing in the presence of a metallocene catalyst. A more preferable form is a reactor TPO type (co) polymer obtained by (co) polymerization in a single reaction layer in the presence of a metallocene catalyst. Specific examples include a propylene homopolymer, a propylene / ethylene copolymer, a propylene / 1-butene copolymer, and a propylene / ethylene / 1-butene copolymer. More preferably, it is a propylene / ethylene copolymer.

  The α-olefin (co) polymer (X-2) obtained using the metallocene catalyst used for the adhesive layer (X) is an α-olefin (co) polymer having a tensile modulus of 100 MPa or less. Preferably, the tensile elastic modulus is in the range of 3 to 90 MPa, and the crystal melting calorie has a peak of 0.5 to 40 J / g or less by differential scanning calorimetry (DSC) measurement in the range of −50 ° C. to 200 ° C. Propylene (co) polymer. More preferably, the tensile modulus is in the range of 5 to 80 MPa, the heat of crystal fusion is in the range of 1 to 20 J / g, and more preferably the tensile modulus is in the range of 5 to 70 MPa, and the heat of crystal fusion is 1 to 10 J. It is an α-olefin (co) polymer having a peak of / g.

  Specifically, the α-olefin (co) polymer (X-2) is, for example, a propylene homopolymer, a propylene / ethylene copolymer, a propylene / ethylene / 1-butene copolymer, a 1-butene homopolymer, 1-butene / ethylene copolymer, 1-butene / propylene copolymer, 4-methylpentene-1 homopolymer, 4-methylpentene-1 / propylene copolymer, 4-methylpentene-1 / 1-butene A copolymer, a 4-methylpentene-1, propylene / 1-butene copolymer, and a propylene / 1-butene copolymer, and preferably a propylene / ethylene / 1-butene copolymer.

  The melt flow rate (MFR) measured at 230 ° C. of the α-olefin (co) polymer (X-2) is in the range of 0.1 to 100 g / 10 minutes, preferably 0.5 to 50 g / 10 minutes. .

  By using the low crystalline α-olefin (co) polymer (X-1) as described above as a part or the whole of the adhesive layer, the stability of the adhesive force over time and the contamination resistance to the adherend A surface protective film having excellent properties can be obtained.

  Metallocene catalysts include transition metal compounds such as cyclopentadiene, indene, fluorene, etc., and titanium, zirconium, hafnium and the like having a cyclopentadiene derivative having a substituent such as an alkyl group in the ring (same or identical). A known type capable of polymerizing olefins using a catalyst mainly composed of a geometrically constrained catalyst, including a bridge type in which two cyclopentadiene derivatives are bonded and a non-bridge type in which the bond is not bonded) Can be used. In addition, any catalyst that can exhibit the narrow molecular weight distribution and the narrow composition distribution, which are the characteristics of the olefin polymer obtained by the metallocene catalyst, is applicable.

  For the adhesive layer (X) in the protective film of the present invention, other crystalline polyolefins, olefin elastomers, styrene elastomers, and tackifiers are used for the purpose of controlling the adhesive force, the adhesive force over time and the unwinding force. It can also be added to the composition.

  As content when using the said crystalline polyolefin, an olefin type elastomer, a styrene type elastomer, and a tackifier as one component of the adhesion layer (X) of the protective film of this invention, (X-1) and (X- 2 to 100 parts by weight, preferably 0.3 to 50 parts by weight, more preferably 0.5 to 20 parts by weight with respect to 100 parts by weight of the composition comprising 2). Addition of crystalline polyolefin, olefin-based elastomer, styrene-based elastomer, and tackifier is preferable because desired adhesive strength can be expressed and adhesive properties suitable for various adherends can be expressed.

  In the surface protective film of the present invention, the composition comprising (X-1) and (X-2) and, if necessary, a composition comprising a crystalline polyolefin, an olefin elastomer, a styrene elastomer, or a tackifier. An adhesive layer (X) can be formed. In the present invention, the adhesive layer (X) is not limited to the properties of the present invention, but is modified with resin modifiers such as acid-modified polyolefins, polyesters, polyamides, antistatic agents, crystal nucleating agents, and antioxidants. You may mix | blend various additives, such as.

  In the present invention, it is also possible to provide at least one base material layer (B) between the surface layer (A) and the adhesive layer (X). For the purpose of controlling the mechanical strength and transparency of the film, and when the adhesive strength between the surface layer (A) and the adhesive layer (X) is insufficient, a polyolefin resin, adhesive resin or adhesive is used as the intermediate layer. You may do it.

  Although there is no restriction | limiting in particular as a base material layer, Generally, crystalline polyolefins, such as a polypropylene and polyethylene with melting | fusing point of 100 degreeC or more, polyester, polyamide, polyolefin-type elastomer, etc. can be used. When the base material layer is used as an adhesive layer, modified polyolefin, polyolefin elastomer, styrene elastomer, polyester elastomer or the like is used. Among these, from the viewpoint of productivity and transparency, it is preferable to use polypropylene or polyolefin elastomer as the intermediate layer.

  A composition comprising the above styrenic elastomer and styrenic oligomer, or a composition in which a crystalline polyolefin and / or an olefinic elastomer is blended with this composition, if necessary, and a resin, if necessary, with this composition The composition containing the modifier or additive can be used as the surface protective film of the present invention by laminating the surface layer (A) or, if necessary, the base material layer (B).

  Although there is no restriction | limiting in particular about the method of laminating | stacking a surface layer (A), adhesion layer (X), and a base material layer (B) as needed, The surface layer film obtained by T-die shaping | molding or inflation shaping | molding previously A method of laminating the adhesive layer (X) or, if necessary, the base material layer (B) by a known laminating method such as extrusion lamination or extrusion coating, or independently forming the base material layer and the adhesive layer as a film. Then, a method of laminating each film by dry lamination, etc. can be mentioned. From the viewpoint of productivity, each of the surface layer (A), the base material layer (B), and the adhesive layer (C) as necessary. Coextrusion molding in which the components are subjected to a multilayer extruder and molded is preferred.

  As thickness of the surface layer (A) in the surface protection film of this invention, it is 0.1-100 micrometers, Preferably it is 0.3-50 micrometers, More preferably, it is 0.5-30 micrometers, More preferably, it is 1-20 micrometers. As thickness of adhesion layer (X), it is 0.1-50 micrometers, Preferably it is 0.3-40 micrometers, More preferably, it is 0.5-30 micrometers.

The thickness of the surface protective film of the present invention is 1 to 300 μm, preferably 2 to 200 μm, more preferably 3 to 100 μm.
By using the surface layer (A), the pressure-sensitive adhesive layer (X), and the base material layer (B) as necessary, the adhesive properties, particularly the adhesive strength excellent for a highly uneven adherend. And a surface protective film excellent in transparency can be obtained, and can be suitably used particularly for building materials and optical applications.
EXAMPLES The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples.

[Evaluation method]
Adhesive strength (acrylic plate):
The acrylic plate is cut to a width of 50 mm and a length of 125 mm, and is attached to this test plate using a 2 kg rubber roller. Next, the peel force when peeled at a speed of 300 mm / min (180 degree peel) is measured, and the peel force per 50 mm width is defined as the adhesive strength (N / 50 mm).
Fisheye (FE):
An A4 size film sample is prepared, and fish eyes with a length of 0.1 mm or more are visually counted. The number of FEs converted per unit area was defined as the number of FEs (pieces / m ² ).

Contamination resistance A surface protective film of a black acrylic plate having a width of 50 mm and a length of 125 mm is attached. After storing at 50 ° C. for 7 days, the film is peeled off and the contamination state on the black acrylic plate is observed. The case where remarkably contamination was observed was indicated as x, the case where a small amount of contamination was observed was indicated as Δ, and the case where no contamination was observed was indicated as ○.
Melt flow rate (MFR):
Based on ASTM D1238, the load was 2.16 kg and the temperature was 230 ° C.

Example 1
The following resin composition is supplied to a three-type three-layer T-die molding machine having a die width of 500 mm, each having a single-screw extruder of 40 mmφ for the surface layer, intermediate layer, and adhesive layer. The surface layer thickness is 10 μm, and the adhesive layer A surface protective film having a thickness of 10 μm, an intermediate layer thickness of 30 μm, and a total thickness of 50 μm was obtained. The evaluation results of the obtained film are shown in Table 1.
Surface layer:
PP-1: Block polypropylene
(Melting point 160 ° C., MFR (230 ° C.) 3 g / 10 min)
Base material layer:
PP-2: Homopolypropylene
(Melting point 160 ° C., MFR (230 ° C.) 7 g / 10 min)
Adhesive layer:
TPO-1: Propylene / ethylene copolymer
(Tensile modulus 240 MPa, MFR = 6 g / 10 min, manufactured with metallocene catalyst)
PEBR-1: Propylene / ethylene / 1-butene copolymer
(Tensile modulus of elasticity 30 MPa, MFR = 7 g / 10 min, produced with metallocene catalyst-with DSC measurement at 50 to 200 ° C., peak of heat of fusion 4 J / g)
MP-1: Propylene / ethylene copolymer (manufactured with metallocene catalyst)
(Tensile modulus 600 MPa, MFR = 7 g / 10 min)
PP-3: Propylene / ethylene / 1-butene copolymer (manufactured with Ziegler-Natta catalyst)
(There is a peak of 65 J / g in DSC measurement at a tensile modulus of 650 MPa and −50 to 200 ° C.)

Example 2 and Comparative Examples 1 and 2
A surface protective film was obtained in the same manner as in Example 1 except that the resin compositions of the various layers were changed to the resin compositions shown in Table 1. The evaluation results of the obtained film are shown in Table 1.

[Effect of the invention]
The surface protective film of the present invention is excellent in adhesive properties and stability over time, transparency, unwinding force and heat resistance, and has a very high industrial utility value as a protective film for optical use, building material use and automotive part use.

Claims (3)

It is a surface protective film comprising at least two layers of a surface layer (A) and an adhesive layer (X), the surface layer (A) is made of a polyolefin resin, and the adhesive layer (X) is obtained by using a metallocene catalyst. A low crystalline α-olefin (co) polymer (X-1) which is composed of 3 or more α-olefins and has a tensile elastic modulus in the range of 100 to 400 MPa and is a reactor TPO
10 to 90% by weight,
And an α-olefin (co) polymer (X-2) having a tensile elastic modulus of less than 100 MPa and obtained using a metallocene catalyst 90 to 10% by weight
A surface protective film formed from a composition comprising (total of (X-1) and (X-2) is 100% by weight).   The low crystalline α-olefin (co) polymer (X-1) constituting the composition of the adhesive layer (X) is a copolymer of propylene and an α-olefin having 2 to 10 carbon atoms (excluding propylene). The surface protective film according to claim 1, wherein: The surface protective film according to claim 1, which is a multilayer film obtained by extrusion molding at least two layers of a surface layer (A) and an adhesive layer (X) from a T-die.