JP2006095955A - Surface protection film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface protection film having an improved paste remainder at the time of removing the film from an object to be protected. <P>SOLUTION: The surface protection film has one surface layer of a substrate layer and another surface layer of an adhesive layer, wherein the substrate layer is a layer making a polyethylene system resin containing an organic based anti-blocking agent and having a density of 900-920 kg/cm<SP>3</SP>a principal component, the adhesive layer is a layer making an ethylene-α-olefin copolymer a principal component, and a 1% secant elastic modulus of this film is 100-170 MPa. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a surface protective film.

Articles such as metal plates such as aluminum and stainless steel used for industrial and architectural purposes, synthetic resin plates such as acrylic and engineering plastic, wood decorative boards, liquid crystal displays, optical film products used for CDs and DVDs, etc. In order to prevent the article from being scratched by contact or friction with an object during processing, storage or transportation of the article, or to prevent the article surface from becoming dirty due to adhesion of dust, etc., a surface protective film is applied to the article. Is being pasted. The surface protective film has an adhesive layer that adheres and adheres to an article and a base material layer that is a non-adhesive layer, and a polyethylene resin is often used for the base material layer. For example, a base material layer linear low density polyethylene and density were blended with high pressure radical polymerization process low-density polyethylene of 0.928 g / cm ³ of density 0.935 g / cm ^3, an adhesive layer comprising the pressure-sensitive adhesive A film having a base layer made of a high-pressure radical polymerization method low-density polyethylene having a density of 0.920 g / cm ³ and an adhesive layer made of a linear low-density polyethylene. (For example, refer to Patent Document 2).

JP-A-5-98219 JP-A-5-229082

However, in the above surface protective film, adhesive residue may be left when the film is peeled off from the object to be protected, which is not sufficiently satisfactory.
Under such circumstances, the problem to be solved by the present invention is to provide a surface protective film having an improved adhesive residue when the film is peeled off from an object to be protected.

  According to the present invention, it is possible to provide a surface protective film with improved adhesive residue when the film is peeled off from an object to be protected. Moreover, the surface protective film of this invention is excellent in slipperiness and blocking resistance, and there is also little white powder generation amount.

The present invention is a surface protective film in which one surface layer is a base material layer and the other surface layer is an adhesive layer, the base material layer contains an organic antiblocking agent, and the density is 900 to 920 kg. / Cm ³ is a layer mainly composed of a polyethylene-based resin, the adhesive layer is a layer mainly composed of an ethylene-α-olefin copolymer, and the 1% secant modulus of the film is 100 to 170 MPa. It is a thing concerning the surface protection film which is.

  A base material layer is a layer which has a polyethylene-type resin as a main component. The polyethylene-based resin is a polymer having a monomer unit based on ethylene as a main unit, a high-pressure low-density polyethylene produced by a high-pressure radical polymerization method, an ethylene-α- produced by a coordination polymerization method or the like. Examples thereof include olefin copolymers. As the α-olefin of the ethylene-α-olefin copolymer, an α-olefin having 3 to 18 carbon atoms is preferably used. 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene , 1-decene and the like, and one or more thereof are used.

The density of the polyethylene-based resin of the base material layer is 900 to 920 kg / cm ³ . If the density is too small, the handling properties of the film may deteriorate. On the other hand, if the density is too high, the substrate layer surface of the film is scraped off due to the friction between the substrate layer surface of the film and the roll during the production of the surface protective film and the bonding to the protected object, May occur. The density is measured according to the method defined in Method A of JIS K7112-1980 after annealing described in JIS K6760-1995.

  The melt flow rate (MFR) of the polyethylene-based resin of the base material layer is preferably 0.1 g / 10 min or more and 0.3 g / 10 min or more from the viewpoint of reducing the extrusion load in film forming. Is more preferable. Moreover, this value is preferably 50 g / 10 min or less, more preferably 20 g / 10 min or less, from the viewpoint of increasing the strength of the film. The MFR is measured by the A method under the conditions of a load of 21.18 N and a temperature of 190 ° C. in accordance with the method defined in JIS K7210-1995.

  Organic anti-blocking agents include polymethyl methacrylate cross-linked product, polymethyl methacrylate, polyacrylic acid, polyacrylic acid cross-linked product, polystyrene, polystyrene cross-linked product, methyl methacrylate / styrene copolymer cross-linked product, polyamide Resin, crosslinked silicone resin, melamine / formaldehyde condensate, benzoguanamine / formaldehyde condensate and the like. These anti-blocking agents may be used alone or in combination of two or more. In general, a polymethyl methacrylate-based crosslinked product is used.

  The particle size (weight average particle size) of the organic anti-blocking agent is preferably 0.5 μm or more, more preferably 3 μm or more, from the viewpoint of enhancing the blocking resistance. Further, from the viewpoint of reducing the dirt of the dies generated during processing, that is, so-called “meani”, it is preferably 30 μm or less, and more preferably 15 μm or less. The particle diameter (weight average particle diameter) is measured by an electric resistance method.

  The content of the organic anti-blocking agent in the base material layer is preferably from the viewpoint of improving the blocking resistance with the total amount of the polyethylene resin and the organic anti-blocking agent in the base material layer being 100% by weight. It is 025% by weight or more, more preferably 0.04% by weight or more. Moreover, from a viewpoint of reducing omission of an antiblocking agent, Preferably it is 1 weight% or less, More preferably, it is 0.5 weight% or less.

  Examples of the organic anti-blocking agent blending method include a method of dry blending a pre-prepared organic anti-blocking agent-containing masterbatch and a polyethylene resin with various blenders such as a Henschel mixer and a tumbler mixer. .

  The adhesive layer is a layer mainly composed of an ethylene-α-olefin copolymer. As the α-olefin of the ethylene-α-olefin copolymer, an α-olefin having 3 to 18 carbon atoms is preferably used, and 1-butene, 1-hexene, 4-methyl-1-pentene, 1- Examples include octene and 1-decene, and one or more of these are used. Examples of the ethylene-α-olefin copolymer include an ethylene-1-butene copolymer, an ethylene-1-hexene copolymer, and an ethylene-1-octene copolymer.

  As the ethylene-α-olefin copolymer constituting the adhesive layer, an ethylene-α-olefin copolymer produced by a Ziegler-Natta solid catalyst is preferable. Specifically, titanium, magnesium and halogen are used. In the presence of a catalyst comprising a solid catalyst component and an organoaluminum compound component, usually 30 to 300 ° C., normal pressure to 30 MPa, in the presence or absence of a solvent, gas-solid, liquid-solid or homogeneous liquid phase And a copolymer produced in (1). As the copolymer, an ethylene-α-olefin copolymer produced by a high-pressure ion polymerization method using a Ziegler-Natta solid catalyst is more preferable.

The density of the ethylene-α-olefin copolymer in the adhesive layer is preferably 935 kg / cm ³ or less from the viewpoint of increasing the adhesive strength of the adhesive layer. Moreover, from a viewpoint of improving workability | operativity at the time of peeling a surface protection film, Preferably it is 910 kg / cm < ³ > or more. The density is measured according to the method defined in Method A of JIS K7112-1980 after annealing described in JIS K6760-1995.

  The melt flow rate (MFR) of the ethylene-α-olefin copolymer of the adhesive layer is preferably 0.1 g / 10 min or more from the viewpoint of reducing the extrusion load in film forming, and is 0.3 g / 10 min. More preferably. Moreover, this value is preferably 50 g / 10 min or less, more preferably 20 g / 10 min or less, from the viewpoint of increasing the strength of the film. The MFR is measured under the conditions of a load of 21.18 N and a temperature of 190 ° C. according to the method defined in JIS K7210-1995.

  If necessary, additives such as an antioxidant, a lubricant, and an antistatic agent may be added to the base material layer and the adhesive layer as long as the effects of the present invention are not impaired.

  The surface protective film of the present invention is a multilayer film having one surface layer as a base material layer and the other surface layer as an adhesive layer, and the 1% secant elastic modulus of the film is 100 to 170 MPa. If the value is too small, the film may not be stretched and handling at the time of bonding to the protected object may be reduced. If the value is too large, the surface protective film is peeled off from the protected object. A phenomenon in which a large number of stripe-like striped patterns remain in a direction perpendicular to the direction, that is, a so-called adhesive residue may occur.

  As a method for producing the surface protective film of the present invention, a known production method, for example, a coextrusion blown film forming method, a coextruded T-die cast film forming method, or the like is used.

  The surface protective film of the present invention is used for surface protection of metal plates such as aluminum and stainless steel, synthetic resin plates such as acrylic and engineering plastic, wood decorative plates, liquid crystal displays, optical film products used for CDs and DVDs, and the like.

Hereinafter, the present invention will be described by way of examples.
The physical properties in the examples were measured according to the following methods.
[Physical properties of polymer]
(1) Density (Unit: kg / m ³ )
It measured according to the method prescribed | regulated to A method among JISK7112-1980. The sample was annealed according to JIS K6760-1995.
(2) Melt flow rate (MFR, unit: g / 10 min)
According to the method defined in JIS K7210-1995, the measurement was performed by the A method under the conditions of a load of 21.18 N and a temperature of 190 ° C.
(3) Particle size (unit: μm)
The particle diameter (weight average particle diameter) was measured by an electric resistance method.
(4) 1% secant modulus (1% SM) (unit: MPa)
A strip-shaped test piece having a width of 2 cm and a length of 12 cm was cut out so that the film processing direction (MD) was the longitudinal direction, and a tensile test was performed using the test piece under conditions of a chuck distance of 60 mm and a tensile speed of 5 mm / min. And a stress-strain curve was measured. From the stress-strain curve, the load at 1% elongation (unit: N) was determined, and 1% SM was determined from the following formula.
1% SM = [F / (t × l)] / [s / L ₀ ] / 10 ⁶
F: Load at 1% elongation (unit: N)
t: Test piece thickness (unit: m)
l: Specimen width (Unit: m, 0.02)
L ₀ : Distance between chucks (Unit: m, 0.06)
s: 1% distortion (Unit: m, 0.0006)
(5) Sliding property (Static friction coefficient μs, Dynamic friction coefficient μk)
The measurement was performed according to JIS K7125-1987. The smaller this value, the better the slipperiness.
(6) Blocking resistance (unit: g / 100 cm ² )
Two 10 cm × 10 cm films were overlapped so that the base layer side and the adhesive layer side were in close contact, and conditions were adjusted for 7 days under a load of 400 g / cm ² in an oven adjusted to 40 ° C. . After the condition adjustment, a load amount necessary for peeling in the vertical direction at a peeling load rate of 20 g / min was measured using a Mackenzie blocking tester (manufactured by Shimadzu Corporation). The smaller this value, the better the blocking resistance.
(7) White powder generation amount Unwinding speed of 2.8 m / min, unwinding amount of 100 m so that the substrate layer surface of the unwound film is rubbed against a metal roll (fixed rotation). It was unwound under the conditions of. After unwinding, the amount of white powder adhering to the metal roll rubbed against the base material layer surface of the film was visually evaluated as follows.
○: No white powder is observed at all.
Δ: Slight white powder is observed.
X: Many white powders are observed.
(8) Amount of adhesive remaining A 10 cm × 25 cm film and a 10 cm × 25 cm polycarbonate film (thickness: 100 μm) are superposed so that the adhesive layer side of the surface protective film is on the polycarbonate film side, and the roll temperature is 40 ° C. and the pressure is 0. Crimping was performed by passing through two rolls under conditions of 49 MPa and a speed of 0.5 m / min.
The surface protective film was peeled off 180 ° by hand from the obtained pressure-bonded product, and the surface of the polycarbonate film was observed to see if there were streaky stripes (= glue residue) in the direction perpendicular to the peeled direction. The street was evaluated.
○: Almost no adhesive residue is observed.
Δ: Some glue residue is observed.
X: Many adhesive residues are observed.

Example 1
[Manufacture of organic anti-blocking agent masterbatch]
10 parts by weight of an organic anti-blocking agent (Nippon Shokubai Co., Ltd. spherical fine particle “Eposta MA1010” (polymethyl methacrylate cross-linked product, particle size: 9.7 μm)) and polyethylene resin (manufactured by Sumitomo Chemical Co., Ltd.) 90 parts by weight of a linear low density polyethylene “Sumikasen E FV402” (d = 915 kg / cm ³ , MFR = 4 g / 10 min)) is melt-mixed using a Banbury mixer, and 10 weights of an organic antiblocking agent is obtained. An organic antiblocking agent masterbatch containing 1% was produced.

[Production of film]
“Sumikasen Hiα CW3006” (ethylene-α-olefin copolymer, d = 923 kg / cm ³ , MFR = 4.8 g / 10 min, Ziegler-Natta solid catalyst, manufactured by Sumitomo Chemical Co., Ltd. 98 parts by weight of a high-pressure method low density polyethylene “Sumikasen L705” (d = 919 kg / cm ³ , MFR = 7 g / 10 min) manufactured by Sumitomo Chemical Co., Ltd. A resin composition (concentration of organic antiblocking agent = 0.2% by weight) mixed with 2 parts by weight of the organic antiblocking agent masterbatch was used. Using a three-layer T die film molding machine having an inner layer extruder, an intermediate layer extruder and an outer layer extruder, the adhesive layer resin is supplied to the inner layer extruder, and the intermediate layer extruder and the outer layer extruder are supplied. The substrate layer resin is supplied to the substrate under the processing conditions of an extruder temperature of 210 ° C., a die temperature of 200 ° C., a chill roll temperature of 25 ° C., a take-off speed of 20 m / min, an adhesive layer thickness of 10 μm, a substrate layer thickness of 20 μm, and a film thickness of 30 μm. A two-layer film of adhesive layer / base material layer was produced. The evaluation results of the obtained film are shown in Table 1.

Example 2
As a resin for the base layer, a resin composition (organic) comprising 99.5 parts by weight of Sumitomo Chemical Co., Ltd. high-pressure method low-density polyethylene “Sumikasen L705” and 0.5 parts by weight of an organic antiblocking agent master batch The same procedure as in Example 1 was performed except that the concentration of the system anti-blocking agent was 0.05% by weight. The evaluation results of the obtained film are shown in Table 1.

Comparative Example 1
As resin for the base material layer, 40 parts by weight of high-pressure method low-density polyethylene “Sumikasen L705” manufactured by Sumitomo Chemical Co., Ltd. and high-density polyethylene “Hi-Zex 3300F” manufactured by Mitsui Chemicals, Inc. (d = 950 kg / cm ³ , MFR = 1.1 g / 10 min) The same procedure as in Example 1 was performed except that a mixture of 60 parts by weight was used. The evaluation results of the obtained film are shown in Table 1.

Claims (4)

One surface layer is a base material layer, and the other surface layer is an adhesive layer, and the base material layer contains an organic antiblocking agent, and the density is 900 to 920 kg / cm ³ . A surface protection in which a polyethylene resin is a main component, the adhesive layer is a layer having an ethylene-α-olefin copolymer as a main component, and the 1% secant modulus of the film is 100 to 170 MPa. the film.   The surface protective film according to claim 1, wherein the particle size of the organic antiblocking agent is 0.5 to 30 μm.   The surface protection film according to claim 1 or 2, wherein the content of the organic antiblocking agent in the base material layer is 0.025 to 1% by weight. The surface protective film according to claim 1, wherein the organic antiblocking agent is a polymethyl methacrylate antiblocking agent.