JPWO2011034045A1 - Surface protection film - Google Patents

Abstract

Provided is a surface protective film excellent in adhesive properties to optical materials, adhesive stability over time, transparency, unwinding properties and heat resistance. 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) 5 to 95% by weight having a main component of 3 or more α-olefin, and a melting point in the range of 50 to 130 ° C., using a metallocene catalyst Surface protective film formed from a composition comprising 95 to 5% by weight of the resulting propylene (co) polymer (X-2) (the total of (X-1) and (X-2) is 100% by weight) .

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, little contamination to adherends, etc., excellent appearance of fish eyes, etc. The present invention relates to a surface protective film that does not damage the adherend and that is easy to draw out from a roll.

  The surface protective film is used by sticking to adherends such as resin products, metal products, glass products, etc. mainly for building materials and optical applications, and prevents them from being scratched or contaminated during transport, storage or processing. 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 to the adherend, has no fish eyes, has an excellent appearance, does not damage the adherend, and is excellent in feeding from a roll. .

  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,
The adhesive layer (X) is a low crystalline α-olefin (co) polymer (X-1) of 5 to 95% by weight based on an α-olefin having 3 or more carbon atoms obtained by using a metallocene catalyst, and Melting point is in the range of 50 to 130 ° C., and 95 to 5% by weight of propylene (co) polymer (X-2) obtained using a metallocene catalyst (total of (X-1) and (X-2) is 100 (Weight%)
It is formed from the composition which consists of this.

  Moreover, as for this invention, (alpha) -olefin (co) polymer (X-1) which is a part of composition which forms the said adhesion layer (X) is propylene, and C2-C10 alpha-olefin (propylene). It is related with the surface protection film characterized by being a copolymer.

  In the present invention, the propylene (co) polymer (X-2), which is a part of the composition forming the adhesive layer (X), is in the range of a melting point of 60 to 120 ° C., and uses a metallocene catalyst. It is related with the surface protection film characterized by being the obtained propylene (co) polymer.

  Furthermore, this invention relates to the surface protection film which is a multilayer film obtained by extrusion-molding at least 2 layer of said surface layer (A) and adhesion layer (X) from T-die.

  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 uses, building materials uses, automobile parts uses and the like.

  Next, the present invention will be described in detail.

  The surface protective film of the present invention comprises at least two layers of a surface layer (A) and an adhesive layer (X), or at least 3 of a surface layer (A), a base material layer (B) and an 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. Examples of polypropylene include homopolypropylene, random polypropylene, block polypropylene, and polyethylene. High pressure method low density polyethylene, linear low density polyethylene, and high density polyethylene can be exemplified. Among these, high-pressure low-density polyethylene from the viewpoint of unwinding, and block containing homopolypropylene, propylene / ethylene copolymer component or propylene / 1-butene / ethylene copolymer component from the viewpoint of transparency and heat resistance Polypropylene is preferably used.

  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 adhesive layer (X) of the surface protective film of the present invention is a low crystalline α-olefin (co) polymer (X-1) mainly composed of an α-olefin having 3 or more carbon atoms obtained using a metallocene catalyst. 5 to 95% by weight, preferably 10 to 90% by weight, more preferably 35 to 75% by weight, and a melting point in the range of 50 to 130 ° C., and a propylene (co) polymer (X) obtained using a metallocene catalyst (X -2) A composition comprising 95 to 5% by weight, preferably 90 to 10% by weight, more preferably 65 to 25% by weight (the total of (X-1) and (X-2) is 100% by weight). Formed from.

  The α-olefin (co) polymer (X-1) obtained using the metallocene catalyst used for the adhesive layer (X) is a differential scanning calorimeter (DSC) measurement in the range of −50 ° C. to 200 ° C., It is a low crystalline α-olefin (co) polymer having a peak with a heat of crystal melting of 0.5 to 40 J / g. Preferably, it is an α-olefin (co) polymer having a crystal heat of fusion in the range of 1 to 20 J / g, more preferably 1 to 10 J / g. The α-olefin (co) polymer (X-1) is a copolymer mainly containing an α-olefin having 3 or more carbon atoms, such as a propylene homopolymer, a propylene / ethylene copolymer, and propylene / ethylene. 1-butene copolymer, 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 copolymer, 4-methylpentene-1, propylene / 1-butene copolymer, propylene / 1-butene copolymer, preferably propylene / It is an ethylene / 1-butene copolymer.

  By using such an α-olefin (co) polymer (X-1) as a part of the adhesive layer, the surface protection is excellent in the stability over time of the adhesive force and the stain resistance to the adherend. A film is obtained.

  The melt flow rate (MFR) measured at 230 ° C. of the α-olefin (co) polymer (X-1) is in the range of 0.1 to 100 g / 10 minutes, preferably 0.5 to 50 g / 10 minutes. .

  The melting point of the propylene (co) polymer (X-2) is in the range of 50 to 130 ° C, preferably in the range of 55 to 130 ° C, more preferably in the range of 60 to 120 ° C. The propylene (co) polymer (X-2) is a crystalline polymer, and is a homopolymer of propylene produced in the presence of a metallocene catalyst or a copolymer of propylene with 2 to 10 carbon atoms (excluding propylene). Specific examples include propylene homopolymers, propylene / ethylene copolymers, propylene / 1-butene copolymers, propylene / ethylene / 1-butene copolymers, and the like. More preferably, it is a propylene / ethylene copolymer.

  Metallocene catalysts include cyclopentadiene, indene, fluorene, symmetric, asymmetric, bridged, and non-bridged ligands composed of cyclopentadiene derivatives such as alkyl-substituted and aryl-substituted compounds, and transitions such as titanium, zirconium, and hafnium. A catalyst composed mainly of a metal compound and a co-catalyst such as an aluminoxane or a boron compound, and other various single-site catalysts such as half metallocene are also used as long as they can polymerize olefins. can do.

  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. One or more kinds of the low crystalline α-olefin (co) polymer (X-1) and propylene (co) polymer (X-2) obtained in this manner are used as necessary. Therefore, when two or more types are used, the molecular weight distribution (Mw / Mn) may be larger than that when one type is used, but the molecular weight distribution (Mw / Mn) is converted to polystyrene. On the basis of the value, a polymer having 1 to 4 is preferable, and a polymer having 1.8 to 4 is particularly preferable.

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

  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). By adding a crystalline polyolefin, an olefin elastomer, a styrene elastomer, or a tackifier, a desired adhesive force can be expressed, and adhesive properties suitable for various adherends can be expressed, which is preferable.

  The pressure-sensitive adhesive layer (X) in the surface protective film of the present invention comprises a composition comprising the above (X-1) and (X-2) and, if necessary, a crystalline polyolefin, an olefin elastomer, a styrene elastomer, and a tackifier. It can form with the composition which added. Further, in the present invention, resin modifiers such as acid-modified polyolefins, polyesters, and polyamides, antistatic agents, crystal nucleating agents, and antioxidants are used as long as the properties of the present invention are not further impaired in the adhesive layer (X). Various additives such as these may be contained.

  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, an adhesive resin or an adhesive is used as the base layer. May be used.

  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. In these, it is preferable to use a polypropylene and polyolefin elastomer as an intermediate | middle layer from the point of productivity and transparency.

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

  The method of laminating the surface layer (A) and the adhesive layer (X), and if necessary, the base material layer (B) is not particularly limited, but the surface layer film obtained in advance by T-die molding or inflation molding. On top of this, the adhesive layer (X) or, if necessary, the base material layer (B) is laminated by a known laminating method such as extrusion lamination or extrusion coating, or the base material layer and the adhesive layer are independently formed into a film. Then, a method of laminating each film by dry lamination, etc. can be mentioned. From the viewpoint of productivity, the surface layer (A), if necessary, the base material layer (B), and the adhesive layer (X) Coextrusion molding in which each component is subjected to molding in a multilayer extruder 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 pressure-sensitive adhesive properties, particularly excellent pressure-sensitive adhesive properties. A surface protective film exhibiting strength and 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 is attached to a black acrylic plate having a width of 50 mm and a length of 125 mm. After storage at 50 ° C. for 7 days, the film is peeled off and the contamination state on the black acrylic plate is confirmed. 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]
For the surface layer, the intermediate layer and the adhesive layer, the resin described below is supplied to the three-layer three-layer T-die molding machine having a die width of 500 mm with a 40 mmφ single-screw extruder by the composition shown in Table 1, A surface protective film having a layer thickness of 10 μm, an adhesive layer 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:
PEBR-1: propylene / ethylene / 1-butene copolymer (ethylene content 10 mol%, 1-butene content 17 mol%,
MDS = 7 g / 10 min, DSC measurement at −50 to 200 ° C.
There is a peak of 4J / g of heat of fusion)
PEBR-2: propylene / ethylene / 1-butene copolymer (with a DSC measurement of −50 to 200 ° C., a heat of fusion of 0.5 J / g
No more peaks)
MP-1: Propylene / ethylene copolymer (Manufactured with metallocene catalyst. Melting point = 115 ° C., MFR = 7 g / 10 min.
Molecular weight distribution based on polystyrene (Mw / Mn) = 2.2)
PP-3: Propylene / ethylene / 1-butene copolymer (manufactured with Ziegler-Natta catalyst, melting point = 138 ° C.,
(With DSC measurement at -50 to 200 ° C, there is a peak of 65 J / g)

[Example 2 and Comparative Examples 1, 2, 3]
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.

Claims (4)

  It is a surface protective film consisting of 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) 5 to 95% by weight having a main component of 3 or more α-olefin, and a melting point in the range of 50 to 130 ° C., using a metallocene catalyst And the resulting propylene (co) polymer (X-2) is formed from a composition comprising 95 to 5% by weight (the total of (X-1) and (X-2) is 100% by weight); Surface protection film.   The α-olefin (co) polymer (X-1), which is part of the composition forming the adhesive layer (X), is a copolymer of propylene and an α-olefin having 2 to 10 carbon atoms (excluding propylene). 2. The surface protective film according to claim 1, wherein the surface protective film is a coalescence.   The α-olefin (co) polymer (X-2), which is a part of the composition forming the adhesive layer (X), is in the range of a melting point of 60 to 120 ° C. and is obtained using a metallocene catalyst. 3. The surface protective film according to claim 1, which is a polymer.   The surface protective film according to any one of claims 1 to 3, which is a multilayer film obtained by extruding at least two layers of a surface layer (A) and an adhesive layer (X) from a T-die.