JP4465079B2 - Surface protection film - Google Patents

Description

（式中、ｎは２以上の整数、Ｘはカップリング剤残基を表す。）
上記ブロック共重合体のなかでも、好ましくは（Ａ）−（Ｂ）−（Ｃ）または（Ａ）−（Ｂ）−（Ａ）ブロック共重合体である。
【０００９】
上記（Ａ）−（Ｂ）−（Ｃ）または（Ａ）−（Ｂ）−（Ａ）ブロック共重合体の構成成分であるスチレンと共役ジエンとの含有量は、重量比で５：９５〜６０：４０が好ましく、より好ましくは７：９３〜４０：６０である。
スチレンの含有量が、５重量％未満では粘着剤の凝集力が低下するため再剥離時に被着体に糊残りが生じ、６０重量％を越えると粘着剤の粘着力が不足して被着体への貼付が困難になる。
【００１０】
また、上記スチレン重合体ブロック（Ａ）と、テーパー共重合体ブロック（Ｃ）におけるスチレンの結合含量は、全モノマーの３〜５０重量％が好ましく、より好ましくは５〜４０重量％、さらに好ましくは５〜２５重量％である。ブロック（Ａ）とブロック（Ｃ）における、スチレンの結合量が、３重量％未満では粘着剤の凝集力が低下するため再剥離時に被着体に糊残りが生じ、また５０重量％を越えると粘着剤の粘着力が不足して被着体への貼付が困難になる。上記ブロック（Ａ）中のスチレンの結合含量は、少なくとも３重量％が好ましく、より好ましくは、３〜２０重量％である。
【００１１】
さらに上記ブロック（Ｂ）中の共役ジエン部分のビニル結合含量は、６０％を超える量が好ましく、より好ましくは７０％以上、さらに好ましくは８０％以上である。ビニル結合含量が６０％以下では粘着性が不足する。ここでいうビニル結合とは、共役ジエン化合物が１，２−もしくは３，４−結合位の二重結合で重合したモノマーユニットを示す。
【００１２】
上記ブロック（Ｂ）中の共役ジエン部分の二重結合の少なくとも８０％が水添により飽和されていることが好ましく、より好ましくは９０％以上、さらに好ましくは９５〜１００％である。水添の割合が８０％未満では耐熱性、耐候性に劣るものとなる。
【００１３】
上記スチレン−ジエン系共重合体の水素添加物の重量平均分子量は、ゲルパーミュエーションクロマトグラフ法によるポリスチレン換算で５万〜４０万が好ましく、より好ましくは８万〜２０万である。
重量平均分子量が、５万未満では粘着剤の凝集力が低下するため再剥離時に被着体に糊残りが生じ、４０万を超えると粘着力が不足すると共に流動性が悪くなる。
【００１４】
上記スチレン−ジエン系共重合体に代えて、（Ｂ）ブロックが、共役ジエンのみからなる重合体（Ｂ’）のものであってもよく、下記一般式に示すように、さらにこれらの繰り返しやカップリングしたものであってもよい。

（式中、ｎは２以上の整数、Ｘはカップリング剤残基を表す。）
【００１５】
本発明における上記粘着剤層に用いられる脂肪酸変性アルキド樹脂とは、エチレングリコール、グリセリン等の多価アルコールと、マレイン酸、フタル酸等の多塩基酸との縮合物を脂肪酸で変性したものであり、例えば、大豆油変性アルキド樹脂、トール油変性アルキド樹脂が挙げられる。これらの市販品としては、「アラキード２５１」「アラキード６３００」（荒川化学社製）等が挙げられる。
【００１６】
上記脂肪酸変性アルキド樹脂の配合量は、上記ゴム系ポリマー１００重量部に対して１〜１５重量部であることが好ましく、さらに好ましくは、３〜１０重量部である。
配合量が、１重量部未満では被着体への汚染性はないが、経時による剥離性が重くなり（剥離性は、５Ｎ／２５ｍｍ以下であることが好ましい）、１５重量部を超えると被着体への接着強度が不足するため自然剥離や浮き等が発生し表面保護フィルムとしての役割が充分でなくなる。
【００１７】
上記粘着剤層には、必要に応じて粘着剤の性能を阻害しない範囲で、紫外線吸収剤、酸化防止剤等を添加することができる。
上記紫外線吸収剤としては、特に限定されず、サリチル酸系、ベンゾフェノン系、ベンゾトリアゾール系、シアノアクリレート系等の通常使用される物が挙げられる。その中でも、ベンゾトリアゾール系の物では、例えば「チヌビン３２６」（チバスペシャルティケミカルズ社製）を添加すると紫外線劣化に対して効果的である。
上記酸化防止剤としては、特に限定されず、フェノール系（モノフェノール系、ビスフェノール系、高分子型フェノール系）、硫黄系、リン系等の通常使用される物が挙げられる。その中でも、高分子型フェノール系の物では、例えば「イルガノックス１０１０」（チバスペシャルティケミカルズ社製）等を添加すると熱劣化に対して効果的である。
【００１８】
本発明における基材層に用いられる熱可塑性樹脂は、特に限定されないが、好ましくは、熱可塑性ポリオレフィンが用いられる。
上記熱可塑性ポリオレフィン系樹脂としては、例えば、低密度ポリエチレン、中密度ポリエチレン、高密度ポリエチレン、直鎖状低密度ポリエチレン、エチレン−α−オレフィン共重合体、プロピレン−α−オレフィン共重合体、エチレン−エチルアクリレート共重合体、エチレン−酢酸ビニル共重合体、エチレン−メチルメタクリレート共重合体、エチレン−ｎ−ブチルアクリレート共重合体、ポリプロピレンの単独重合体、ランダム共重合体、ブロック共重合体等が挙げられ、これらは単独で用いられてもよく、２種以上が併用されてもよい。
【００１９】
上記基材層の厚みは、使用目的によって異なるが、３０〜１００μｍが好ましく、粘着剤層の厚みは、２〜１５μｍが好ましい。
【００２０】
本発明の表面保護フィルムの製造方法は、例えば、基材層と粘着剤層とを共押出によって積層一体化する方法；基材層を成膜した後でラミネートにより粘着剤層を基材層上に積層一体化する方法などが挙げられる。
前者の方法においては、インフレーション法、Ｔダイ法等公知の方法が用いられ、後者の方法においては、粘着剤溶液を塗工する溶液塗工法、ドライラミネーション法、Ｔダイによる押出コーティング法等が用いられる。これらの中で共押出による熱溶融押出法が品質上、経済上から好ましい。尚、溶液塗工法の場合は、基材層と粘着剤層との間の接合強度を高めるために基材を予めプライマー処理することが好ましく、プライマー処理によって糊残り現象を確実に防止することができる。
【００２１】
（作用）
本発明では、粘着剤層を上述の配合組成とすることによって、貼付後被着体から剥離する際に容易に剥離でき、被着体表面に汚れ、糊残りや貼付けた跡を防止することができる。
【００２２】
【発明の実施の形態】
以下に、本発明の実施例を説明する。
【００２３】
（実施例１〜３、比較例１，２）
表１に示した配合量の、スチレン−ジエン系ブロック共重合体（Ａ）−（Ｂ）−（Ｃ）の水素添加物［全スチレン含量＝１０重量％、ブロック（Ａ）（Ｃ）の結合スチレン含量＝４．５重量％、ブロック（Ｂ）中のブタジエン部分のビニル結合含量＝８０重量％、Ｍｗ＝２５万］、大豆油変性アルキド樹脂「アラキード２５１」（荒川化学社製）、及び酸化防止剤「イルガノックス１０１０」（チバスペシャルティケミカルズ社製）からなる粘着剤層と、熱可塑性ポリオレフィン系樹脂として低密度ポリエチレン樹脂「ミラソン１２」（ＭＦＲ＝３．０ｇ／１０分（１９０℃）、三井化学社製）からなる基材層とをＴダイ法により共押出することにより、基材層厚み４７μｍ、粘着剤層厚み５μｍとが積層一体化された表面保護フィルムを得た。
【００２４】
（比較例３，４）
上記実施例の大豆油変性アルキド樹脂「アラキード２５１」（荒川化学社製）に代えて、脂肪酸アミド「アルフローＨ５０Ｓ」（日本油脂社製）を使用した以外は実施例と同様にして表面保護フィルムを得た。なお、配合量は表１に記載した。
【００２５】
上記表面保護フィルムについて下記の性能評価を行い、その結果を表１に示した。
（１）初期粘着力
表面保護フィルムを、室温２３℃、相対湿度６５％の環境下で看板用塗装鋼板（表面グロス８０％）にラミネート機を用いて線圧１９．６Ｎ／ｃｍ、３００ｍｍ／分の速度で貼付けた状態で３０分間放置した後、ＪＩＳ Ｚ ０２３７に準拠して２５ｍｍ幅における１８０度剥離強度をそれぞれ測定した。
【００２６】
（２）経時粘着力
表面保護フィルムを、室温２３℃、相対湿度６５％の環境下で看板用塗装鋼板（表面グロス８０％）にラミネート機を用いて線圧１９．６Ｎ／ｃｍ、３００ｍｍ／分の速度で貼付けた状態で７０℃のギアオーブン中に７日間放置した後、ＪＩＳ Ｚ ０２３７に準拠して２５ｍｍ幅における１８０度剥離強度を測定した。
【００２７】
（３）被着体汚染
上記（１）及び（２）の剥離強度の測定時において、剥離後の被着体表面の汚染の有無を濡れ試験ＪＩＳ Ｋ６７６８に準拠して濡れ試薬を塗布し評価した。濡れ性が３３ダイン以下では、インクの種類により塗装できないことがある。
【００２８】
【表１】

【００２９】
【発明の効果】
本発明の表面保護フィルムは、上述の構成であり、被着体に対する初期密着性が良好で経時接着亢進性が小さく、かつ用済み後被着体から剥離する際に糊残りなく容易に剥離でき、しかも被着体表面を汚染することがない。従って、表面保護フィルムを剥離した後、塗装や印刷が施される看板用塗装鋼板等に、好適に用いられる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a surface protective film, and more particularly, to temporarily adhere to the surface of a synthetic resin plate, a metal plate, a decorative plywood, a coated coated steel plate, various nameplates, etc., particularly a painted steel plate of an automobile, or a coated resin plate. The present invention relates to a surface protective film used in the above.
[0002]
[Prior art]
Conventionally, surface protection films have been used frequently to prevent the surface from getting dirty or scratched when processing or transporting synthetic resin plates, metal plates, decorative plywood, various nameplates, etc. Has been. The surface protective film has a configuration in which an adhesive layer is formed on one surface of a base material layer made of thermoplastic resin or paper.
In use, the surface of the adherend is protected by temporarily attaching it to the surface of the adherend such as a synthetic resin plate from the pressure-sensitive adhesive layer side, thereby preventing dirt from being attached or damaged.
[0003]
Since the surface protective film is finally peeled off from the adherend surface, it is preferable that the surface protective film has an adhesive property that can be easily temporarily attached to the adherend surface. After use, the surface protective film peels off easily from the adherend surface. It is preferable that the surface of the adherend is not contaminated.
[0004]
Conventionally, various surface protective films have been proposed as satisfying the above requirements. For example, JP-A-7-324145 discloses a block copolymer represented by general formulas A-B-A and A-B (A is a styrene polymer block, and B is a butadiene polymer block) 100. A pressure-sensitive adhesive sheet for surface protection having a pressure-sensitive adhesive layer formed from a composition containing parts by weight and 0.05 to 5 parts by weight of a fatty acid amide is disclosed.
[0005]
However, in the composition of the pressure-sensitive adhesive layer described in the above publication, for example, when it is used for surface protection of a coated steel sheet such as a signboard that is coated after the protective film is peeled off, it is stored in a place with a high room temperature. When it is stored for a long time, the surface of the adherend after peeling is contaminated, and there is a problem that the plate does not get paint.
[0006]
[Problems to be solved by the invention]
The present invention solves the above-mentioned problems, has good initial adhesion to the adherend, low adhesion enhancement with time, and can be easily peeled off without adhesive residue when peeled from the adherend after use. An object of the present invention is to provide a surface protective film that does not cause contamination on the surface.
[0007]
[Means for Solving the Problems]
In the present invention, it is a surface protective film in which a pressure-sensitive adhesive layer is laminated and integrated on a base material layer made of a thermoplastic resin, and the pressure-sensitive adhesive layer comprises 100 parts by weight of a rubber-based polymer and 1 to 15 fatty acid-modified alkyd resins. A surface protective film comprising a weight part is provided.
[0008]
It does not specifically limit as a rubber-type polymer used for the said adhesive layer in this invention, For example, a polyisobutylene, a butyl rubber, a styrene-type elastomer etc. are used. Of these, hydrogenated products of styrene-diene hydrocarbon copolymers are preferably used.
As a hydrogenated product of the above styrene-diene hydrocarbon copolymer, (A)-(B) block copolymer comprising a styrene polymer block (A) and a random block copolymer (B) of styrene and conjugated diene. (A)-(B)-(C) block copolymer comprising a polymer, or a tapered block (C) in which styrene gradually increases among styrene and a conjugated diene if necessary, or a styrene polymer block ( (A)-(B)-(A) block copolymer comprising A). Further, as shown in the following general formula, these may be further repeated or coupled.

(In the formula, n represents an integer of 2 or more, and X represents a coupling agent residue.)
Among the above block copolymers, (A)-(B)-(C) or (A)-(B)-(A) block copolymers are preferable.
[0009]
The content of styrene and conjugated diene, which are constituent components of the (A)-(B)-(C) or (A)-(B)-(A) block copolymer, is from 5:95 to 5 by weight. 60:40 is preferable, and more preferably 7:93 to 40:60.
If the styrene content is less than 5% by weight, the cohesive strength of the pressure-sensitive adhesive is reduced, so that adhesive residue is left on the adherend during re-peeling. If it exceeds 60% by weight, the pressure-sensitive adhesive has insufficient adhesive strength and is to be adhered. It becomes difficult to stick to.
[0010]
The styrene bond content in the styrene polymer block (A) and the tapered copolymer block (C) is preferably 3 to 50% by weight, more preferably 5 to 40% by weight, and still more preferably. 5 to 25% by weight. In the block (A) and the block (C), when the amount of styrene bonded is less than 3% by weight, the cohesive strength of the pressure-sensitive adhesive is lowered, so that adhesive residue is generated on the adherend during re-peeling, and when the amount exceeds 50% by weight. Adhesive strength of the pressure-sensitive adhesive is insufficient, and sticking to the adherend becomes difficult. The styrene bond content in the block (A) is preferably at least 3% by weight, more preferably 3 to 20% by weight.
[0011]
Furthermore, the vinyl bond content of the conjugated diene moiety in the block (B) is preferably more than 60%, more preferably 70% or more, and even more preferably 80% or more. When the vinyl bond content is 60% or less, the tackiness is insufficient. The vinyl bond as used herein refers to a monomer unit obtained by polymerizing a conjugated diene compound with a double bond at a 1,2- or 3,4-bond position.
[0012]
It is preferable that at least 80% of the double bond of the conjugated diene moiety in the block (B) is saturated by hydrogenation, more preferably 90% or more, and further preferably 95 to 100%. When the ratio of hydrogenation is less than 80%, the heat resistance and weather resistance are poor.
[0013]
The weight average molecular weight of the hydrogenated product of the styrene-diene copolymer is preferably 50,000 to 400,000, more preferably 80,000 to 200,000 in terms of polystyrene by gel permeation chromatography.
If the weight average molecular weight is less than 50,000, the cohesive force of the pressure-sensitive adhesive is reduced, so that adhesive residue is generated on the adherend during re-peeling, and if it exceeds 400,000, the adhesive force is insufficient and the fluidity is deteriorated.
[0014]
Instead of the styrene-diene copolymer, the block (B) may be a polymer (B ′) composed only of conjugated diene, and as shown in the following general formula, It may be coupled.

(In the formula, n represents an integer of 2 or more, and X represents a coupling agent residue.)
[0015]
The fatty acid-modified alkyd resin used for the pressure-sensitive adhesive layer in the present invention is a product obtained by modifying a condensate of a polyhydric alcohol such as ethylene glycol or glycerin and a polybasic acid such as maleic acid or phthalic acid with a fatty acid. Examples thereof include soybean oil-modified alkyd resin and tall oil-modified alkyd resin. Examples of these commercially available products include “Arachid 251” and “Arachid 6300” (manufactured by Arakawa Chemical Co., Ltd.).
[0016]
The amount of the fatty acid-modified alkyd resin is preferably 1 to 15 parts by weight, more preferably 3 to 10 parts by weight, based on 100 parts by weight of the rubber-based polymer.
When the blending amount is less than 1 part by weight, there is no contamination to the adherend, but the peelability with time increases, and the peelability is preferably 5 N / 25 mm or less. Since the adhesive strength to the adherend is insufficient, natural peeling or floating occurs and the role as a surface protective film becomes insufficient.
[0017]
An ultraviolet absorber, an antioxidant, etc. can be added to the said adhesive layer in the range which does not inhibit the performance of an adhesive as needed.
The ultraviolet absorber is not particularly limited, and examples include commonly used products such as salicylic acid, benzophenone, benzotriazole, and cyanoacrylate. Among them, for benzotriazole-based products, for example, “Tinuvin 326” (manufactured by Ciba Specialty Chemicals) is effective against ultraviolet deterioration.
The antioxidant is not particularly limited, and examples thereof include commonly used products such as phenols (monophenols, bisphenols, polymer phenols), sulfurs, and phosphoruss. Among them, in the case of a polymer type phenol-based product, for example, “Irganox 1010” (manufactured by Ciba Specialty Chemicals) or the like is effective against thermal deterioration.
[0018]
Although the thermoplastic resin used for the base material layer in the present invention is not particularly limited, a thermoplastic polyolefin is preferably used.
Examples of the thermoplastic polyolefin resin include low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, ethylene-α-olefin copolymer, propylene-α-olefin copolymer, ethylene- Examples include ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, ethylene-n-butyl acrylate copolymer, polypropylene homopolymer, random copolymer, block copolymer, etc. These may be used alone or in combination of two or more.
[0019]
Although the thickness of the said base material layer changes with purposes of use, 30-100 micrometers is preferable and the thickness of an adhesive layer has 2-15 micrometers preferable.
[0020]
The method for producing the surface protective film of the present invention includes, for example, a method in which a base material layer and an adhesive layer are laminated and integrated by coextrusion; after the base material layer is formed, the adhesive layer is formed on the base material layer by lamination. And the like.
In the former method, a known method such as an inflation method or a T-die method is used, and in the latter method, a solution coating method for applying an adhesive solution, a dry lamination method, an extrusion coating method using a T die, or the like is used. It is done. Among these, the hot melt extrusion method by coextrusion is preferable from the viewpoint of quality and economy. In the case of the solution coating method, it is preferable to prime the substrate in advance in order to increase the bonding strength between the substrate layer and the pressure-sensitive adhesive layer, and the primer treatment can reliably prevent the adhesive residue phenomenon. it can.
[0021]
(Function)
In the present invention, the pressure-sensitive adhesive layer has the above-described composition, so that it can be easily peeled off when peeled from the adherend after sticking, and the adherend surface can be prevented from becoming dirty, adhesive residue and pasted marks. it can.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Examples of the present invention will be described below.
[0023]
(Examples 1 to 3, Comparative Examples 1 and 2)
Hydrogenated product of styrene-diene block copolymer (A)-(B)-(C) having a blending amount shown in Table 1 [total styrene content = 10% by weight, bond of blocks (A) (C) Styrene content = 4.5% by weight, vinyl bond content of butadiene part in block (B) = 80% by weight, Mw = 250,000], soybean oil-modified alkyd resin “Arachid 251” (Arakawa Chemical Co., Ltd.), and oxidation A pressure-sensitive adhesive layer composed of an inhibitor “Irganox 1010” (manufactured by Ciba Specialty Chemicals), a low-density polyethylene resin “Mirason 12” (MFR = 3.0 g / 10 min (190 ° C.) as a thermoplastic polyolefin resin, Mitsui A surface protective film in which a base material layer thickness of 47 μm and an adhesive layer thickness of 5 μm were laminated and integrated was obtained by co-extrusion with a base material layer made of Chemical Co., Ltd. by a T-die method. .
[0024]
(Comparative Examples 3 and 4)
In place of the soybean oil-modified alkyd resin “Arachid 251” (Arakawa Chemical Co., Ltd.) in the above example, a surface protective film was prepared in the same manner as in the example except that the fatty acid amide “Alflow H50S” (Nippon Yushi Co., Ltd.) was used. Obtained. The blending amounts are shown in Table 1.
[0025]
The following performance evaluation was performed on the surface protective film, and the results are shown in Table 1.
(1) Initial pressure adhesion surface protective film is applied to a steel sheet for signboard (surface gloss 80%) in a room temperature of 23 ° C. and a relative humidity of 65% by using a laminating machine and linear pressure of 19.6 N / cm, 300 mm / min. After being left for 30 minutes in a state of being pasted at a speed of 180 °, the 180 ° peel strength at a width of 25 mm was measured in accordance with JIS Z 0237.
[0026]
(2) Adhesive force with time The surface protective film was applied to a coated steel sheet for signboard (surface gloss 80%) in a room temperature of 23 ° C. and a relative humidity of 65% using a laminating machine, with a linear pressure of 19.6 N / cm, 300 mm / min. After being left in a gear oven at 70 ° C. for 7 days in a state of being pasted at a speed of 180 °, the 180 ° peel strength at a width of 25 mm was measured in accordance with JIS Z 0237.
[0027]
(3) Contamination of adherend When measuring the peel strengths in (1) and (2) above, the presence or absence of contamination on the surface of the adherend after peeling was evaluated by applying a wetting reagent according to JIS K6768. . If the wettability is 33 dynes or less, it may not be possible to paint depending on the type of ink.
[0028]
[Table 1]

[0029]
【The invention's effect】
The surface protective film of the present invention has the above-described configuration, has good initial adhesion to the adherend, has low adhesion enhancement with time, and can be easily peeled off without adhesive residue when peeled off after being used. In addition, the adherend surface is not contaminated. Therefore, after peeling off a surface protective film, it uses suitably for the painted steel plate for signboards etc. by which coating and printing are given.

Claims (1)

A surface protective film in which a pressure-sensitive adhesive layer is laminated and integrated on a base material layer made of a thermoplastic resin,
The pressure-sensitive adhesive layer contains 100 parts by weight of a rubber-based polymer and 1 to 15 parts by weight of a fatty acid-modified alkyd resin.