JP4855302B2 - 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. More specifically, the present invention relates to a surface protective film that is excellent in adhesive properties, transparency, and heat resistance, has little contamination to an adherend, and is easy to be drawn 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 mixed with foreign matter, but also transparent so that product inspection can be performed with the surface protective film applied, and even when applied at high temperatures. Properties such as the development of adhesive strength are desired.
Furthermore, with the advent of a wide variety of adherends in recent years, with the surface protective film attached, the adhesive strength over time that can withstand long-time transportation and storage, and the surface protective film have been peeled off. The property of not contaminating the adherend later is also required.

  On the other hand, when the surface protective film is used for building materials or automotive parts, it may be thermoformed with the surface protective film attached, and high heat resistance is required.

  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 2006-116769 A

  The present invention has properties required as a surface protective film for protecting optical products, building material products and automobile parts during storage, transportation, processing and inspection, in particular, adhesive properties, adhesive strength stability over time, and transparency. An object of the present invention is to provide a surface protective film excellent in heat resistance, stain resistance and roll-out property 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
1. 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 formed from the ethylene polymer (a),
The adhesive layer (X) comprises 20 to 100 mol% of an α-olefin having 3 or more carbon atoms as a constituent component, an olefin elastomer (b-1) having a melting point of 65 ° C. or lower or a melting point not observed, and an α having 4 or more carbon atoms. -A surface protective film characterized by being formed from a composition (b) comprising an olefin polymer (b-2) having an olefin of 50 to 100 mol% as a constituent and a melting point of 70 ° C or higher,
2. The surface protective film according to claim 1, wherein the olefin elastomer (b-1) is a propylene copolymer,
3. The surface protective film according to 1 or 2, wherein the olefin elastomer (b-1) is a propylene copolymer, and the total number of carbon atoms of each monomer is 8 or more,
4). The surface protective film according to any one of 1 to 3, wherein the olefin polymer (b-2) is a butene polymer,
5. The surface protective film according to any one of 1 to 4, 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,
It is.

  The surface protective film of the present invention is excellent in adhesive properties, transparency, unwinding power and heat resistance, adhesive strength stability over time, and adherend contamination.

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).

The surface layer (A) is formed from an ethylene polymer (a).
The melt flow rate (abbreviated as MFR ₁₉₀ ) of the ethylene polymer (a) measured at 190 ° C. is 0.01 to 20 g / 10 minutes, preferably 0.03 to 15 g / 10 minutes, more preferably 0.8. It is in the range of 05-12 g / 10 minutes.

The density of the ethylene polymer (a) is 0.900 to 0.960 g / cm ³ , preferably 0.905 to 0.950 g / cm ³ , more preferably 0.910 to 0.940 g / cm ³ . Is in range.

As a more preferred ethylene polymer (a), the relationship between the melt tension (abbreviated as MT) measured at 190 ° C. and the MFR ₁₉₀ satisfies the following formula (1).
40 × (MFR ₁₉₀ ) ^−0.67 ≦ MT ≦ 250 × (MFR ₁₉₀ ) ^−0.67
(1)
Here, the melt tension (MT) is a value obtained by measuring a stress when a melted ethylene polymer is stretched at a constant speed. Specifically, using Toyo Seiki MT measuring instrument, a value (unit: measured at a resin temperature of 190 ° C., an extrusion speed of 15 mm / min, a winding speed of 15 m / min, a nozzle diameter of 2.09 mmφ, and a nozzle length of 8 mm. mN).
When the MFR, MT and density of the ethylene polymer (a) are in the above ranges, the moldability of the surface protective film of the present invention and the feedability from the roll are improved.

  Such an ethylene-based polymer (a) means an ethylene homopolymer or an ethylene copolymer. In the presence of a catalyst capable of polymerizing ethylene, ethylene homopolymerization or ethylene and other α- In addition to ethylene homopolymers and ethylene / α-olefin copolymers that can be obtained by copolymerizing olefins, high-pressure low-density polyethylene or long-chain branched low-density polyethylene can be used. High pressure method low density polyethylene is more preferable.

The surface layer (A) in the surface protective film of the present invention is formed from the ethylene polymer (a).
The ethylene polymer (a) used as the surface layer (A) has an antistatic agent, a release agent, an antioxidant, a weathering agent, a crystal nucleating agent within the range that does not impair the characteristics as the surface protective film of the present invention It is also possible to add various additives such as polyolefin, polyester, polyamide, elastomer and other resin modifiers.

  The ethylene-based polymer (a) and additives and modifiers added as necessary are kneaded with, for example, a single-screw or twin-screw extruder or a feeder ruder, and further processed into a film. However, it can also be directly put into a T-die molding machine that also has an extruder to form the surface layer of the surface protective film of the present invention.

  The adhesive layer (X) comprises 20 to 100 mol% of an α-olefin having 3 or more carbon atoms as a constituent component, an olefin elastomer (b-1) having a melting point of 65 ° C. or lower or no melting point observed, and an α having 4 or more carbon atoms. -It is formed from the composition (b) which consists of 50-100 mol% of olefins as a structural component, and consists of an olefin polymer (b-2) whose melting | fusing point is 70 degreeC or more.

  The olefin elastomer (b-1) is an olefin polymer composed of 20 to 100 mol%, preferably 40 to 100 mol%, more preferably 60 to 100 mol% of an α-olefin having 3 or more carbon atoms. The melting point as measured by a differential scanning calorimeter (DSB) is 65 ° C. or lower or no melting point is observed, preferably the melting point is 50 ° C. or lower or low crystalline or amorphous. Here, when 2 or more types of α-olefins having 3 or more carbon atoms are contained in the olefin elastomer (b-1), the total content thereof is shown. Examples of the α-olefin having 3 or more carbon atoms include propylene, 1-butene, 4-methylpentene-1, 1-hexene, 1-octene, 1-decene, 1-dodecene, and the like. -Butene, 4-methylpentene-1. More preferred are propylene and 1-butene.

  Preferred olefin-based elastomer (b-1) is a propylene-based polymer composed of 20 to 100 mol%, preferably 30 to 90 mol% of a propylene component, and a melting point of 50 ° C. or lower or is not observed. Amorphous or low crystalline propylene homopolymer, propylene / ethylene copolymer, propylene / 1-butene copolymer, propylene / ethylene / 1-butene copolymer, propylene / 4-methylpentene-1 copolymer , A propylene / 1-butene / 4-methylpentene-1 copolymer. More preferably, it is a propylene copolymer in which the total number of carbon atoms of each monomer as a constituent component is 8 or more, preferably 9 to 20, specifically, a propylene / ethylene / 1-butene copolymer. , Propylene / 4-methylpentene-1 copolymer, propylene / 1-butene / 4-methylpentene-1 copolymer. More preferred is a propylene / ethylene / 1-butene copolymer.

  The olefin polymer (b-2) is composed of 50 to 100 mol%, preferably 60 to 100 mol% of an α-olefin having 4 or more carbon atoms, preferably 4 to 10 carbon atoms, and a melting point of 70 ° C or higher. Preferably, it has the characteristic of 80-140 degreeC.

The MFR ₁₉₀ of the olefin polymer (b-2) is in the range of 0.01 to 70 g / 10 minutes, preferably 0.05 to 50 g / 10 minutes, more preferably 0.1 to 40 g / 10 minutes.

  Specific examples of the preferred olefin polymer (b-2) include 1-butene homopolymer, 1-butene / propylene copolymer, and 1-butene / ethylene copolymer.

The pressure-sensitive adhesive layer (X) of the surface protective film of the present invention is formed from the composition (b) comprising the olefin elastomer (b-1) and the olefin polymer (b-2).
The content of the olefin elastomer (b-1) in the composition (b) is 5 to 95% by weight, preferably 20 to 95% by weight, more preferably 50 to 90% by weight. Here, the total amount of the olefin elastomer (b-1) and the olefin polymer (b-2) is 100% by weight.

  Although the composition (b) in the present invention can be used alone, it is used as a composition with an olefin-based elastomer or styrene-based elastomer different from the other (b-1) for the purpose of controlling the adhesive strength. You can also

  Examples of the olefin elastomer include an α-olefin polymer or copolymer having 2 to 20 carbon atoms, or a copolymer of ethylene and an unsaturated carboxylic acid or unsaturated carboxylic acid ester. Specifically, ethylene / propylene copolymer, ethylene / 1-butene copolymer, ethylene / 1-hexene copolymer, ethylene / 4-methylpentene-1 copolymer, ethylene / 1-octene copolymer 4-methylpentene-1 homopolymer, ethylene / vinyl acetate copolymer, ethylene / methacrylic acid copolymer, ethylene / methyl methacrylate copolymer, and the like.

  As the styrene elastomer, a known styrene elastomer having a polystyrene phase as a hard segment can be used. Specifically, styrene / butadiene copolymer (SBR), styrene / isoprene / styrene copolymer (SIS), styrene / butadiene / styrene copolymer (SBS), styrene / ethylene / butadiene / styrene copolymer ( SEBS), and their hydrides.

  By using the composition (b) alone or as a component, the adhesive layer (X) in the surface protective film of the present invention can be formed. In the present invention, a resin modifier such as a polyolefin such as polyethylene or polypropylene, an acid-modified polyolefin, a polyester or a polyamide, an antistatic agent, a crystal nucleating agent, or an antioxidant, as long as the characteristics of the present invention are not impaired. Various additives such as these may be contained.

The said composition (b) and the resin modifier or additive added as needed can be made into the surface protection film of this invention by laminating | stacking with the said surface layer (A).
The method for laminating the surface layer (A) and the pressure-sensitive adhesive layer (X) is not particularly limited. However, known methods such as extrusion lamination and extrusion coating on a surface layer film obtained in advance by T-die molding or inflation molding. The method of laminating by the above-mentioned laminating method, the method of laminating each film by dry lamination after forming the surface layer and the adhesive layer independently into a film, etc. are mentioned. From the viewpoint of productivity, the surface layer, the adhesive layer Coextrusion molding in which each of the above components is subjected to molding in a multilayer extruder is preferred.

In the present invention, it is possible to provide at least one intermediate layer between the surface layer (A) and the adhesive layer (X). Moreover, when the adhesive force with the surface layer (A) and the pressure-sensitive adhesive layer (X) is insufficient, an adhesive or an adhesive layer may be used as the intermediate layer.
Although there is no restriction | limiting in particular as an intermediate | middle 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 intermediate 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.

As thickness of the surface layer (A) in the surface protection film of this invention, it is 0.05-200 micrometers, Preferably it is 0.5-100 micrometers, More preferably, it is 1-30 micrometers, More preferably, it is 1-15 micrometers. As thickness of adhesion layer (X), it is 0.05-50micro, Preferably it is 0.3-40micro, More preferably, it is 0.5-30micrometer.
The thickness of the surface protective film of the present invention is 0.1 to 500 μm, preferably 0.5 to 400 μm, more preferably 3 to 300 μm, including an intermediate layer that may be provided as necessary.

  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 force:
The acrylic plate is cut into a width of 50 mm and a length of 125 mm, and is attached to the test plate using a pressure roll laminator. Next, the peel force when peeled at a speed of 300 mm / min (180 degree peel) is measured, and the peel force per 25 mm width is defined as the adhesive strength (N / 25 mm).
Here, the measurement of sticking and peeling force was performed on the conditions of 23 degreeC.
Rewinding force (feeding ability) :
Using a roll-shaped sample, the peeling force (N / 25 mm) at the time of peeling from the roll at a speed of 300 mm / min is measured and used as the rewinding force.
Hayes:
Based on JIS K7105, it measured with the film of thickness 50 micrometers.
Adherent contamination:
The surface protective film was affixed to the acrylic plate and stored in an oven at 50 ° C. for 3 days, and then the surface protective film was peeled off and the contamination state of the acrylic plate surface was observed. The case where no contamination was observed was marked with ◯, and the case where contamination was observed was marked with ×.

Example 1
The following resin composition is supplied to a three-layer three-layer T-die molding machine having a die width of 500 mm, which is equipped with a 30 mmφ single screw extruder for the surface layer and the adhesive layer and a 40 mmφ single screw extruder for the intermediate layer, A surface protective film having a 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:
High pressure method low density polyethylene (Mirason 1770P manufactured by Prime Polymer, density 0.927 g / bm ³ , MFR ₁₉₀ = 5.9 g / 10 min, MT = 35 mN) 100% by weight,
Middle layer:
Block polypropylene [Propylene / ethylene copolymer having a melting point = 160 ° C., MFR ₂₃₀ = 85 g / 10 min of propylene polymer (b-1) and a propylene content of 75 mol%, [η] = 2.3 dl / g 15% by weight composition] 85% by weight and 15% by weight of ethylene / butene copolymer (MFR ₁₉₀ = 0.5 g / 10 min, 1-butene content 19 mol%).
Adhesive layer:
Propylene / ethylene / 1-butene copolymer (ethylene content 12 mol%, butene content 19 mol%, melting point not observed, MFR = 7 g / 10 min) 66.5 wt%,
Homopolypropylene (melting point = 160 ° C., MFR ₂₃₀ = 7 g / 10 min) 3.5% by weight
1-butene homopolymer (Tafmer BL4000, Mitsui Chemicals, melting point 125 ° C., MFR ₁₉₀ = 1.8 g / 10 min)

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

HPLDPE;
High-pressure low-density polyethylene (brand name: Mirason 1770P, density 0.927 g / cm ³ , MFR ₁₉₀ = 5.9 g / 10 min, MT = 32 mN, manufactured by Prime Polymer Co., Ltd.)
b-PP;
Block Polypropylene (Melting point = 160 ° C., MFR ₂₃₀ = 8 g / 10 min propylene polymer 85% by weight and propylene content 75 mol%, [η] = 2.3 dl / g propylene / ethylene copolymer 15% by weight A composition produced by a multistage polymerization method)
PEBR-1;
Propylene / ethylene / 1-butene copolymer (ethylene content 12 mol%, butene content 19 mol%, no melting point observed, MFR ₂₃₀ = 7 g / 10 min)
r-PP;
Random polypropylene (brand name: F327, melting point = 138 ° C., MFR ₂₃₀ = 7 g / 10 min, manufactured by Prime Polymer Co., Ltd.)
h-PP;
Homopolypropylene (melting point = 160 ° C, MFR ₂₃₀ = 7 g / 10 min)
PB;
Butene homopolymer (brand name: BL4000, MFR ₁₉₀ = 1.8 g / 10 min, melting point 125 ° C., manufactured by Mitsui Chemicals)

  The surface protective film of the present invention is excellent in adhesive properties, transparency, unwinding power and heat resistance, adhesive stability over time, adherend contamination, and protection for optical applications, building materials applications, and automotive parts applications. Industrial value as a film is extremely high.

Claims (7)

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 formed from an ethylene-based polymer (a), and the adhesive layer (X) has a carbon number. Consists of 20 to 100 mol% of 3 or more α-olefin, and constitutes olefin elastomer (b-1) having a melting point of 65 ° C. or lower or no melting point and 50 to 100 mol% of α-olefin having 4 or more carbon atoms. As a component, the melting point is 80 to 140 ° C., and MFR ₁₉₀ is formed from a composition (b) composed of an olefin polymer (b-2) of 0.1 to 40 g / min ,
The ethylene-based polymer (a) is a high pressure method low density polyethylene,
The relationship between the melt tension (MT) measured at 190 ° C. and the melt flow rate (MFR ₁₉₀ ) in the ethylene polymer (a) is represented by the following formula (1).
40 × (MFR ₁₉₀ ) ^−0.67 ≦ MT ≦ 250 × (MFR ₁₉₀ ) ^−0.67 (1)
The surface protection film characterized by satisfy | filling .   Between the surface layer (A) and the adhesive layer (X), at least one selected from crystalline polyolefin, polyester, polyamide, polyolefin elastomer, modified polyolefin, styrene elastomer and polyester elastomer having a melting point of 100 ° C. or higher The surface protective film according to claim 1, further comprising a formed intermediate layer. The surface protective film according to claim 1 or 2, wherein the olefin elastomer (b-1) is a propylene copolymer. The surface protective film according to any one of claims 1 to 3, wherein the olefin elastomer (b-1) is a propylene copolymer, and the total carbon number of each monomer is 8 or more. The surface protective film according to any one of claims 1 to 4 , wherein the olefin polymer (b-2) is a butene polymer. In the adhesive layer (X), when the total amount of the olefin elastomer (b-1) and the olefin polymer (b-2) is 100% by weight, the content of the olefin elastomer (b-1) is 50 to 50%. The surface protective film according to claim 1, wherein the surface protective film is 90% by weight. The surface protective film according to any one of claims 1 to 6 , 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.