JP3746559B2 - Release film - Google Patents

Description

【００２６】
但し、Ｄ単位、Ｔ単位およびＱ単位においてＲはメチル基等のアルキル基またはフェニル基等の芳香族炭化水素基を示す。
【００２７】
（２）ポリジメチルシロキサンポリマー中にシリカフィラーを配合することにより離型層中の−Ｓｉ−ＯＨ基の濃度が高くなるよう調整して表面張力を増加させたもの。尚、このシリカフィラーは平均粒径が１μｍ以下のものが好ましい。平均粒径が１μｍを超えるとフイルムの曇り度（ヘイズ）が大きくなり、透明性を要求される用途に用いる際に支障となることがあったり、加工工程でフイルムを走行させる際に離型層の削れが発生することがあるため好ましくない。また、シリカフィラーの配合割合は固形分濃度で０．１〜１重量％であることが好ましい。配合割合が０．１重量％よりも少ないと所望の濡れ性が得られないことがあり、１重量％を超えるとシリカフィラーが離型層から削れて脱落することがあるため好ましくない。
【００２８】
（３）ポリジメチルシロキサンポリマー中のメチル基の一部を嵩高いフェニル基で置換した変性ポリジメチルシロキサン。フェニル基の立体障害により、例えばポリマー中の−Ｓｉ−Ｏ−Ｓｉ−結合の回りの回転運動が抑制され、その結果離型層表面のメチル基の濃度が減少するため表面張力を増加させることができる。尚、このフェニル基の置換割合は２０〜６０モル％であることが好ましい。この置換割合が２０モル％よりも少ないと所望の濡れ性が得られないことがあり、６０モル％を超えると離型層と各種粘着剤や各種シートとの離型性が不良となることがあるため好ましくない。
【００２９】
（４）シラノール基やメトキシ基等の反応活性基を比較的高濃度で有するポリジメチルシロキサンポリマーと、分子内に水酸基を有する有機樹脂（例えばアルキッド樹脂、ポリエステル樹脂、アクリル樹脂等）とを反応させて得られる変性ポリジメチルシロキサン。この変性ポリジメチルシロキサン中のジメチルシロキサン成分の割合は１０〜３０重量％であることが好ましい。この割合が１０重量％よりも少ないと離型性が不良となることがあり、３０重量％を超えると所望の濡れ性が得られないことがあるため好ましくない。
【００３０】
［その他の配合剤］
本発明における離型層には本発明の目的を妨げない範囲で公知の各種添加剤を配合することができる。この添加剤としては、例えば紫外線吸収剤、顔料、消泡剤、滑剤（タルク、クレー、アルミナ等）を挙げることができる。
【００３１】
［離型層の塗設方法］
本発明においては、ポリエステルフイルムの少なくとも片面に離型層を設けるが、この離型層は例えば離型層の成分を含む水性塗液をフイルムに塗布し、加熱乾燥することにより塗設することができる。この水性塗液の塗布方法としては、公知の任意の塗工法が適用でき、例えばロールコーター法、ブレードコーター法等を挙げることができるが、これらの方法に限定されるものではない。
【００３２】
［接着層］
本発明においては、ポリエステルフイルムと離型層との密着性を高めるためにポリエステルフイルムの少なくとも片面に接着層を設け、該接着層の上に更に離型層を積層することができる。この接着層には例えばシランカップリング剤を好ましく用いることができる。このシランカップリング剤としては，一般式Ｙ−Ｓｉ−Ｘ₃ で示されるものを挙げることができる。ここで、Ｙは例えばアミノ基、エポキシ基、ビニル基、メタクリル基、メルカプト基等で代表される官能基、Ｘはアルコキシ基で代表される加水分解性の官能基を示す。上記の接着層の好ましい厚みは０．０１〜５μｍ程度であり、特に０．０２〜２μｍ程度である。接着層の厚みが上記の範囲であるとポリエステルフイルムと離型層の密着性が良好となり、また接着層を設けたポリエステルフイルムがブロッキングし難いため取り扱う際に支障が生じ難い。
【００３３】
【実施例】
以下、実施例をあげて本発明を更に説明する。尚、フイルムの各特性値は下記の方法で測定した。
【００３４】
１．γ_L max
エタノールに対しエチレングリコールを適宜割合で配合し、表面張力が２０〜４０dyne/cm の範囲にある数種の標準液を調整する。この表面張力はデュヌイの輪環引上げ法により測定する。次いで、この標準液をフイルムの離型層上に滴下して標準液と離型層との接触角（θ）を測定する。得られた接触角（θ）からｃｏｓθ値を算出し、このｃｏｓθ値と上記の方法により測定された表面張力とのプロット（Ｚｉｓｍａｎプロット）を作成しその直線の傾きをｂとする。また、このＺｉｓｍａｎプロットの直線とｃｏｓθ＝１で示される直線との交点における表面張力の値をγ_C （臨界表面張力）とする。かくして得られたｂ、γ_C を用い下記式（Ｉ）からγ_L max を求めた。
【００３５】
【数４】
γ_L max ＝１／ｂ＋γ_C ／２ ……式（Ｉ）
【００３６】
式（Ｉ）で、ｂは上記のＺｉｓｍａｎプロットより求まる定数、γ_C は上記の方法で求まる臨界表面張力を示す。
【００３７】
２．水系塗料の耐ハジキ性
下記組成のセラミック粉体分散スラリーを調整する。
(a) チタン酸バリウム粉末：１００重量部
(b) 水溶性アクリルエマルジョン：９〜１３重量部
(c) 水溶性ポリウレタン樹脂：１重量部
(d) ポリカルボン酸アンモニウム：１重量部
(e) 水：１０〜２０重量部
(f) アンモニア：１重量部
【００３８】
セラミック粉体分散スラリーの調整はボールミルにて、ヘッグマングラインドゲージで７以上の分散状態となるよう行なう。次いで、このセラミック粉体分散スラリーを１ｍｉｌの間隙を有するストレートエッジアプリケーター離型フイルムの離型層面に塗工し、１４０℃にて１分間乾燥後、塗工エッジのハジキの程度を観察し下記の基準にて水系塗料の耐ハジキ性を評価した。
Ａ：ハジキが観察されない ……耐ハジキ性良好
Ｂ：ハジキが若干観察される……耐ハジキ性やや良好
Ｃ：ハジキが観察される ……耐ハジキ性不良
【００３９】
３．剥離強度（ラビングテスト）
ポリエステルフイルムの離型層面にポリエステル粘着テープ（ニットー３１Ｂ）を貼合わせ、５ｋｇの圧着ローラーで圧着し２０時間放置後、離型層と粘着テープとの剥離力を引張り試験機にて測定した。
【００４０】
４．残存接着率
ポリエステル粘着テープ（ニットー３１Ｂ）をＪＩＳ・Ｇ４３０５に規定する冷間圧延ステンレス板（ＳＵＳ３０４）に貼付けた後の剥離力を測定し、基礎接着力（ｆ₀ ）とする。また前記ポリエステル粘着テープをサンプルフイルムの離型層塗設面に５ｋｇの圧着ローラーで圧着し、３０秒間放置した後粘着テープを剥がす。そして剥がした粘着テープを上記のステンレス板に貼り、該貼合部の剥離力を測定し、残留接着力（ｆ）とする。得られた基礎接着力（ｆ₀ ）と残留接着力（ｆ）より下記式を用いて残留接着率を求める。
【００４１】
【数５】
残留接着率（％）＝（ｆ／ｆ₀ ）×１００
【００４２】
５．異物個数の測定
二軸配向ポリエステルフイルムサンプルを日本工業規格の標準原紙寸法Ａ５判に準じた大きさ（縦２０９〜２１０ｍｍ×横１４８〜１４９ｍｍ：面積約３１０ｃｍ² ）に切取り、このフイルムの全範囲をクロスニコル法にて目視検査による異物検査をおこなった。次いで検出されたサンプルフイルム中の異物を、光学顕微鏡を用いて透過光により観察し、光学的に異常な範囲として観察される部分の最大径を異物の大きさとした。尚、異物周辺に存在する空洞（ボイド）が光学的に異常な範囲として観察される場合は異物の大きさに含めた。更に異物の大きさが２５μｍ以上のものと、５μｍ以上２５μｍ未満ものとに分け、それぞれのＡ５版当りの異物個数を計測した。
【００４３】
［実施例１］
ポリエチレンテレフタレート１００重量部に対し、滑剤として風力分級機により２５μｍ以上の凝集粒子を取り除いたアルミナ粒子０．０５重量部を配合したポリエステル組成物を押出機（押出機先端とダイの間に焼結金属製のフィルターを装着したもの）に供給し、溶融したポリエチレンテレフタレートをフイルム状に押出し、２０℃の回転冷却ドラムに接触、急冷して未延伸フイルムとした。次いで、該未延伸フイルムを表１に示す延伸倍率で逐次二軸延伸し、更に表１に示す条件で熱固定して厚さ３８μｍ、光線透過率８８％の二軸配向ポリエチレンテレフタレートフイルムを得た。この二軸配向ポリエチレンテレフタレートフイルムのフイルム中の異物個数測定結果を表１に示す。
【００４４】
次に、この二軸配向ポリエチレンテレフタレートフイルムの片面に、下記組成のシリコーン樹脂塗液を塗布量（ｗｅｔ）８ｇ／ｍ² で塗布し、１３０℃×３０秒の条件で乾燥、硬化処理して塗膜厚み０．２４μｍの離型フイルムを得た。
【００４５】
ポリジメチルシロキサンとジメチルハイドロジェンシランの混合溶液に白金触媒を加えて付加反応させるタイプの硬化型シリコーン（信越シリコーン（株）製・ＫＳ−８４７（Ｈ））をメチルエチルケトン、メチルイソブチルケトン及びトルエンの混合溶剤中に溶解させ、更に下記式及び前記（Ｑ単位）からなるシリコーンレジンを上記硬化型シリコーンに対し固形分比で４０重量％となるよう配合し、全体の固形分濃度が３％の溶液を作成した。
【００４６】
この溶液を、二軸延伸ポリエチレンテレフタレートフイルム（厚さ３８μｍ）に６ｇ／ｍ² （ｗｅｔ）の塗布量で塗布し、加熱温度１４０℃、加熱時間１分で乾燥および硬化反応を行なわせて離型フイルムを作成した。この離型フイルムの特性を表１に示す。
【００４７】
【化２】

【００４８】
［実施例２］
シリコーンレジンの替わりに平均粒子径０．５μｍのシリカフィラーを用い、該シリカフィラーを上記硬化型シリコーンに対し固形分比で０．３重量％となるよう配合した以外は実施例１と同様にして離型フイルムを作成した。この離型フイルムの特性を表１に示す。
【００４９】
［実施例３］
硬化型シリコーンとして、主鎖ポリマー中のメチル基（−ＣＨ₃ ）の３０モル％をフェニル基（−Ｃ₆ Ｈ₅ ）で置換した硬化型シリコーンを用いた以外は実施例１と同様にして離型フイルムを作成した。この離型フイルムの特性を表１に示す。
【００５０】
［実施例４］
硬化型シリコーンおよびシリコーンレジンの替わりに、アルキッド樹脂とメラミン樹脂の混合物９０重量部に、末端基に−ＳｉＯＨ基を有するジメチルポリシロキサンを１０重量部を配合した組成物を用いた以外は実施例１と同様にして離型フイルムを作成した。この離型フイルムの特性を表１に示す。
【００５１】
［比較例１］
シリコーンレジンを含有しない溶液を用いた以外は実施例１と同様にして離型フイルムを作成した。この離型フイルムの特性を表１に示す。
【００５２】
［比較例２］
硬化型シリコーンとして、主鎖ポリマー中のメチル基（−ＣＨ₃ ）の１０モル％をフェニル基（−Ｃ₆ Ｈ₅ ）で置換した硬化型シリコーンを用いた以外は実施例３と同様にして離型フイルムを作成した。この離型フイルムの特性を表１に示す。
【００５３】
［比較例３］
硬化型シリコーンとして、主鎖ポリマー中のメチル基（−ＣＨ₃ ）の７０モル％をフェニル基（−Ｃ₆ Ｈ₅ ）で置換した硬化型シリコーンを用いた以外は実施例３と同様にして離型フイルムを作成した。この離型フイルムの特性を表１に示す。
【００５４】
［比較例４］
アルキッド樹脂とメラミン樹脂の混合物９５重量部に、末端基に−ＳｉＯＨ基を有するジメチルポリシロキサンを５重量部を配合した組成物を用いた以外は実施例４と同様にして離型フイルムを作成した。この離型フイルムの特性を表１に示す。
【００５５】
［比較例５］
アルキッド樹脂とメラミン樹脂の混合物６５重量部に、末端基に−ＳｉＯＨ基を有するジメチルポリシロキサンを３５重量部を配合した組成物を用いた以外は実施例４と同様にして離型フイルムを作成した。この離型フイルムの特性を表１に示す。
【００５６】
［比較例６］
焼結金属製のフィルターを装着しない以外は実施例１と同様にして二軸延伸ポリエステルフイルムをつくり、更に実施例１と同様にして離型フイルム及び積層体をつくり、各特性を評価した。この結果を表１に示す。
【００５７】
【表１】

【００５８】
表１に示す結果より明らかなように、実施例１〜４に示した本発明の離型フイルムは水系塗料に対する濡れ性、剥離強度および残留接着率に優れ、フイルム中に存在する異物が少ないものであった。
【００５９】
尚、剥離強度の好ましい範囲は５〜２００ｇ／ｃｍである。剥離強度が５ｇ／ｃｍ以下であると、離型フイルムに樹脂シート等を積層した積層シートを巻き取る際等に樹脂シート等が離型フイルムから剥離してしまうことがあるため好ましくない。また、剥離強度が２００ｇ／ｃｍ以上であると、積層シートから樹脂シート等を剥離分離して使用する際に剥離が困難となることがあるため好ましくない。
【００６０】
また、残留接着率の好ましい範囲は８５％以上である。残留接着率が８５％未満であると、例えば離型フイルムをロール状に巻いて保管する際に、離型層を構成する成分が隣接するフイルムの表面に転写（いわゆる背面転写）し、離型層の特性が不良となったり、隣接フイルム表面の接着性等の特性が不良となることがあるため好ましくない。
【００６１】
【発明の効果】
本発明の離型フイルムは、離型層に特定の最大表面張力（γLmax）を有するものを用い、ベースフイルムに異物の少ないポリエステルフイルムを用いたものであるため、各種被膜やシート成形用に水系塗液を用いた際に濡れ性に優れ、各種樹脂シート、樹脂被膜やセラミックシート等に対する剥離性に優れる、かつ樹脂シート、樹脂被膜、セラミックシート等の成形用キャリヤーフイルムに用いた際にピンホール等の欠点の無いシートや被膜を得ることができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a release film, and more particularly useful for a protective film for an aqueous adhesive film, or an aqueous resin slurry such as an aqueous adhesive solution or an aqueous slurry such as an aqueous ceramic slurry, and a resin or ceramic sheet. The present invention relates to a release film useful for a carrier film used for forming a film.
[0002]
[Prior art]
Release films are currently widely used as protective films for various adhesive films or as carrier films used for forming various sheets and films. Natural rubber resins, synthetic rubber resins, acrylic resins, and the like are used for these various adhesive films. Examples of various sheets and coatings include vinyl chloride sheets, ceramic raw sheets, and pressure-sensitive adhesive coatings, and the release film is used as a carrier film when molding these sheets and coatings. For example, a vinyl chloride sheet for a marking sheet or the like can be formed by casting (coating) a vinyl chloride solution on a carrier film (release film) and then removing the solvent by heating. In addition, a slurry in which ceramic powder and a binder agent are dispersed in a liquid medium is cast (coated) on a carrier film, and then the liquid medium is heated and removed to form a ceramic raw sheet.
[0003]
Conventionally, organic solvents have been used for the solvent and liquid medium used in the above coating. Recently, however, water is increasingly used in place of organic solvents. That is, an aqueous solution of an adhesive such as a resin tackifier is used for application of the adhesive solution, and an aqueous dispersion slurry is used for application of the slurry. The reason for this is that water has no danger of fire and environmental pollution like an organic solvent, so that the chemical solution can be handled very easily in the concentration adjustment process of the solution or slurry, the coating or heating removal process, and the like.
[0004]
However, compared with organic solvents, water has a higher surface tension (water surface tension, γ _L is about 73 dyne / cm 2), and a release layer having a small surface energy (for example, the surface tension of a silicone release layer, γ _S is 19). (Approx. 21 dyne / cm), when a coating solution such as an aqueous solution or water-dispersed slurry is applied, the coating solution may not be uniformly applied to the surface of the release layer (so-called repellency). It becomes a big problem. In order to improve this problem, for example, a method of increasing the viscosity of the coating liquid (aqueous solution or water-dispersed slurry) and a method of blending a surfactant to reduce the surface tension of the coating liquid can be considered. However, the high viscosity method has a drawback that leveling during coating is difficult and the surface of the coating film is difficult to be smooth, and the method of incorporating a surfactant adversely affects the properties of the release layer due to the surfactant. There are drawbacks.
[0005]
Further, when a large foreign matter (for example, agglomerated particles of a lubricant or a deteriorated resin) is present in the film, the convex shape of the film surface due to the foreign matter is transferred to the resin sheet or the ceramic green sheet in a concave shape. The portion transferred into the concave shape becomes a shape defect of the resin sheet or the ceramic green sheet. In particular, in the case of a ceramic green sheet with a thin film thickness, it does not stop at a mere dent but becomes a pinhole that penetrates, and this is a defect that various defects occur in subsequent processes.
[0006]
[Problems to be solved by the invention]
The object of the present invention is to eliminate the disadvantages of the prior art, and to have a release layer surface that does not cause repelling (good wettability) even when an aqueous coating liquid is used for forming various films and sheets. It is an object of the present invention to provide a release film having a release layer surface that can be peeled off with an appropriate force on an adhesive film or sheet (good release properties).
[0007]
[Means for Solving the Problems]
An object of the present invention is to provide a release layer in which a release layer having a maximum surface tension (γ _L max) of 30 to 50 dyne / cm determined by the following formula (I) is provided on at least one surface of a polyester film. a type film, characterized in that there is no 25μm or more foreign substances to the polyester film of one side length 210mm and the side length breadth of 148mm of the Cartesian thereto (area 310.8cm ²⁾ per in the film This is achieved by a release film.
[0008]
[Expression 2]
γ _L max = 1 / b + γ _C / 2 Formula (I)
[In formula (I), b is a constant determined from the slope of the zisman plot, and γ _C is the critical surface tension. ]
[0009]
Here, b is a constant obtained from the following zisman plot, and γ _C is a critical surface tension obtained by the following method. That is, several kinds of standard solutions having a surface tension in the range of 20 to 40 dyne / cm are prepared, and this standard solution is dropped on the release layer of the film to contact angle (θ) between the standard solution and the release layer. Measure. The cos θ value is calculated from the obtained contact angle (θ), the cos θ value and the surface tension value of the standard solution are plotted (Zisman plot), and the slope of the straight line is b. The value of the surface tension at the intersection of the straight line of this Zisman plot and the straight line indicated by cos θ = 1 is γ _C (critical surface tension).
[0010]
The γ _L max is defined as the surface tension of the liquid that maximizes the adhesion force (W) represented by the following formula (II).
[0011]
[Equation 3]
W = γ _S + γ _L −γ _SL ...... Formula (II)
[0012]
In the formula (II), γ _S represents the surface tension of the solid, γ _L represents the surface tension of the liquid, and γ _SL represents the interfacial tension between the solid and the liquid.
[0013]
[Polyester film]
In the present invention, a polyester film is used as the film base. However, it is preferable to use a polyester film having good transparency for applications requiring transparency, and a biaxially stretched polyester film is particularly preferable. For applications that require light-shielding properties, it is preferable to use a polyester film containing an inorganic pigment, and a biaxially stretched polyester film containing a pigment such as TiO ₂ or SiO ₂ is particularly preferred.
[0014]
The polyester constituting such a polyester film is preferably a crystalline linear saturated polyester comprising an aromatic dibasic acid component and a diol component. For example, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene-2, Examples thereof include 6-naphthalate.
[0015]
In order to improve the slipperiness of the film, the above polyester contains organic or inorganic fine particles having an average particle size of about 0.01 to 25 μm, more preferably about 0.01 to 2 μm as a lubricant. 0.005 to 2% by weight, more preferably 0.05 to 0.5% by weight. Specific examples of such fine particles include inorganic particles such as calcium carbonate, kaolin, silicon oxide, and barium sulfate, and organic particles such as crosslinked polystyrene resin particles, crosslinked silicone resin particles, and crosslinked acrylic resin particles. Alternatively, by depositing fine particles from the catalyst residue used in the polyester synthesis reaction, fine irregularities can be formed on the film surface, and the slipperiness of the film can be improved.
[0016]
In addition, other improvers can be blended in the polyester. For example, a compound having a sulfonate group such as sodium dodecylbenzenesulfonate can be contained as an antistatic agent. Polyesters that do not contain these modifiers can also be used.
[0017]
The polyester film in the present invention can be produced by a conventionally known method. For example, a biaxially stretched polyester film is obtained by drying a polyester, melting it in an extruder, extruding it from a die (for example, T-die, I-die, etc.) onto a rotating cooling drum, quenching it into an unstretched film, The unstretched film can be produced by stretching in a biaxial direction and heat-setting as necessary. The thickness of the film is not particularly limited, but is preferably 5 to 250 μm.
[0018]
Further, the polyester film of the present invention, in the film per length width of 148mm sides of Cartesian thereto and 210mm length of one side (area 310.8cm ²⁾ (a standard sheet size A5 size of Japanese Industrial Standards (It may be abbreviated as “per A5 size” hereinafter, meaning a film of a similar size.) No foreign matter of 25 μm or more is present.
[0019]
If there is a foreign matter of 25 μm or more per A5 size of polyester film, when the release film is used as a carrier film, a concave shape defect or a pinhole is generated in the obtained resin sheet or ceramic green sheet. The quality of the sheet or the ceramic green sheet is poor, and the yield is significantly reduced. In addition, foreign matter of 5 μm or more and less than 25 μm is allowed to some extent, but depending on the presence state in the film, a convex part with a large protrusion height is formed on the surface of the film, and the same quality defect and yield reduction as described above may occur. is there. Accordingly, it is preferable to exclude foreign matters having a size of 5 μm or more and less than 25 μm as much as possible, preferably 10 or less, and particularly preferably 3 or less, per A5 plate of the polyester film. If the number of foreign matters of 5 μm or more and less than 25 μm is 10 or less per A5 size polyester film, the probability of pinholes occurring in the resulting resin sheet or ceramic green sheet is 10% when the release film is used as a carrier film. This level of occurrence is acceptable.
[0020]
Here, the foreign matter in the present invention is a foreign matter that can be optically detected in a visual inspection by the crossed Nicols method. For example, inorganic and organic lubricants blended when producing a polyester film are aggregated and coarsened. And foreign substances generated or mixed in the process of manufacturing the polyester film.
[0021]
Moreover, the size of the foreign material in the present invention is measured as follows. That is, the foreign matter in the biaxially stretched polyester film optically detected in the visual inspection by the crossed Nicol method is separately observed with transmitted light using an optical microscope, and the portion observed as an optically abnormal range is observed. The maximum diameter is the size of the foreign matter. In addition, for example, when a film is stretched around a foreign substance or the like that is formed by agglomeration of a lubricant, a void is generated. When this cavity is observed as an optically abnormal range, the size of the foreign substance Included. In order to measure the number of foreign matter, the sample film was cut into a size (210 mm long × 148 mm wide: area 310.8 cm ² ) according to the Japanese Industrial Standard Standard Base Paper Size A5 size, and foreign matter in the entire range of this film. This was done by measuring the number.
[0022]
[Release layer]
In the present invention, a release layer having a maximum surface tension represented by γ _L max of 30 to 50 dyne / cm is provided on at least one side of the polyester film. The value of γ _L max is preferably 35 to 45 dyne / cm 3. If this γ _L max is less than 30 dyne / cm, the repellency increases when an aqueous solution or water-dispersed slurry is applied, resulting in defects in which the coating film becomes uneven or missing. On the other hand, if γ _L max exceeds 50 dyne / cm 2, the adhesiveness between the pressure-sensitive adhesive or sheet and the release layer becomes too large, and it becomes difficult to peel the pressure-sensitive adhesive or sheet from the release film.
[0023]
In the present invention, the constituent component of the release layer is not particularly defined as long as it becomes a release layer having a γ _L max of 30 to 50 dyne / cm 2, for example, addition type and / or polycondensation type release. A release layer having a γ _L max of 30 to 50 dyne / cm can be obtained by blending the following components with polydimethylsiloxane for paper or using the following modified polydimethylsiloxane.
[0024]
(1) A polydimethylsiloxane polymer blended with a silicone resin having the structure of the following D unit, T unit and / or Q unit to adjust the concentration of methyl groups in the release layer to increase the surface tension. . In addition, it is preferable that the compounding ratio of this silicone resin is 20 to 60 weight% in solid content concentration. If the blending ratio is less than 20% by weight, the wettability of the release layer may be poor, and if it exceeds 60% by weight, the release layer may become too hard and the abrasion resistance may be poor. Absent.
[0025]
[Chemical 1]

[0026]
In the D unit, T unit, and Q unit, R represents an alkyl group such as a methyl group or an aromatic hydrocarbon group such as a phenyl group.
[0027]
(2) The surface tension is increased by adjusting the concentration of -Si-OH groups in the release layer by adding a silica filler to the polydimethylsiloxane polymer. The silica filler preferably has an average particle size of 1 μm or less. When the average particle size exceeds 1 μm, the haze of the film increases, which may be a hindrance when used in applications that require transparency, or when the film is run in the processing process, the release layer. This is not preferable because the shaving may occur. Moreover, it is preferable that the compounding ratio of a silica filler is 0.1 to 1 weight% in solid content concentration. If the blending ratio is less than 0.1% by weight, desired wettability may not be obtained, and if it exceeds 1% by weight, the silica filler may be scraped off from the release layer, which is not preferable.
[0028]
(3) Modified polydimethylsiloxane in which a part of methyl groups in the polydimethylsiloxane polymer is substituted with bulky phenyl groups. Due to steric hindrance of the phenyl group, for example, rotational movement around the —Si—O—Si— bond in the polymer is suppressed, and as a result, the concentration of methyl groups on the surface of the release layer is decreased, so that the surface tension can be increased. it can. In addition, it is preferable that the substitution rate of this phenyl group is 20-60 mol%. If this substitution ratio is less than 20 mol%, the desired wettability may not be obtained, and if it exceeds 60 mol%, the releasability between the release layer and various adhesives or various sheets may be poor. This is not preferable.
[0029]
(4) A polydimethylsiloxane polymer having a relatively high concentration of reactive groups such as silanol groups and methoxy groups is reacted with an organic resin having a hydroxyl group in the molecule (for example, alkyd resin, polyester resin, acrylic resin, etc.). Modified polydimethylsiloxane. The proportion of the dimethylsiloxane component in the modified polydimethylsiloxane is preferably 10 to 30% by weight. If this ratio is less than 10% by weight, the releasability may be poor, and if it exceeds 30% by weight, the desired wettability may not be obtained.
[0030]
[Other ingredients]
Various known additives can be blended in the release layer in the present invention as long as the object of the present invention is not hindered. Examples of the additive include an ultraviolet absorber, a pigment, an antifoaming agent, and a lubricant (talc, clay, alumina, etc.).
[0031]
[Coating method of release layer]
In the present invention, a release layer is provided on at least one side of the polyester film, and this release layer can be applied by applying an aqueous coating liquid containing components of the release layer to the film and drying by heating. it can. As a method for applying the aqueous coating liquid, any known coating method can be applied, and examples thereof include a roll coater method and a blade coater method, but are not limited to these methods.
[0032]
[Adhesive layer]
In the present invention, in order to enhance the adhesion between the polyester film and the release layer, an adhesive layer can be provided on at least one side of the polyester film, and a release layer can be further laminated on the adhesive layer. For example, a silane coupling agent can be preferably used for this adhesive layer. Examples of the silane coupling agent include those represented by the general formula Y—Si—X ₃ . Here, Y represents, for example, a functional group represented by an amino group, an epoxy group, a vinyl group, a methacryl group, a mercapto group, and the like, and X represents a hydrolyzable functional group represented by an alkoxy group. The preferable thickness of the adhesive layer is about 0.01 to 5 μm, particularly about 0.02 to 2 μm. When the thickness of the adhesive layer is within the above range, the adhesiveness between the polyester film and the release layer becomes good, and the polyester film provided with the adhesive layer is difficult to block, so that it is difficult to cause trouble in handling.
[0033]
【Example】
Hereinafter, the present invention will be further described with reference to examples. Each characteristic value of the film was measured by the following method.
[0034]
1. γ _L max
Ethylene glycol is blended at an appropriate ratio with respect to ethanol, and several standard solutions having a surface tension in the range of 20 to 40 dyne / cm 2 are prepared. This surface tension is measured by Dunui's ring pull-up method. Next, this standard solution is dropped on the release layer of the film, and the contact angle (θ) between the standard solution and the release layer is measured. A cos θ value is calculated from the obtained contact angle (θ), a plot (Zisman plot) of the cos θ value and the surface tension measured by the above method is created, and the slope of the straight line is b. The value of the surface tension at the intersection of the straight line of this Zisman plot and the straight line indicated by cos θ = 1 is γ _C (critical surface tension). Using b and γ _C thus obtained, γ _L max was determined from the following formula (I).
[0035]
[Expression 4]
γ _L max = 1 / b + γ _C / 2 Formula (I)
[0036]
In the formula (I), b represents a constant obtained from the above Zisman plot, and γ _C represents a critical surface tension obtained by the above method.
[0037]
2. Repelling resistance of water-based paint A ceramic powder dispersion slurry having the following composition is prepared.
(a) Barium titanate powder: 100 parts by weight
(b) Water-soluble acrylic emulsion: 9 to 13 parts by weight
(c) Water-soluble polyurethane resin: 1 part by weight
(d) Ammonium polycarboxylate: 1 part by weight
(e) Water: 10 to 20 parts by weight
(f) Ammonia: 1 part by weight
The ceramic powder-dispersed slurry is adjusted by a ball mill so that a dispersion state of 7 or more is achieved with a Hegman grind gauge. Next, this ceramic powder dispersion slurry was applied to the release layer surface of a straight edge applicator release film having a 1 mil gap, dried at 140 ° C. for 1 minute, and observed for the degree of repellency at the coating edge. The repellency resistance of the water-based paint was evaluated according to the standard.
A: No repellency is observed .... Repelling resistance is good. B: Repelling is slightly observed .... Repelling resistance is somewhat good. C: Repelling is slightly observed .... Repelling resistance is poor.
3. Peel strength (rubbing test)
A polyester adhesive tape (Nitto 31B) was bonded to the release layer surface of the polyester film, pressed with a 5 kg pressure roller and allowed to stand for 20 hours, and then the peeling force between the release layer and the adhesive tape was measured with a tensile tester.
[0040]
4). The peel strength after sticking the remaining adhesive rate polyester pressure-sensitive adhesive tape (Nitto 31B) to the cold-rolled stainless steel plate (SUS304) specified in JIS G4305 is measured to obtain the basic adhesive force (f ₀ ). The polyester adhesive tape is pressure-bonded to the release layer coating surface of the sample film with a 5 kg pressure roller, left for 30 seconds, and then peeled off. And the peeled adhesive tape is affixed on said stainless steel plate, the peeling force of this bonding part is measured, and it is set as residual adhesive force (f). Based on the obtained basic adhesive strength (f ₀ ) and residual adhesive strength (f), the residual adhesive rate is obtained using the following formula.
[0041]
[Equation 5]
Residual adhesion rate (%) = (f / f ₀ ) × 100
[0042]
5. Measurement of the number of foreign materials A biaxially oriented polyester film sample was cut to a size (209-210 mm long x 148-149 mm wide: area about 310 cm ² ) according to the standard A5 standard base paper dimensions of the Japanese Industrial Standard, and the entire range of this film was removed. Foreign matter inspection by visual inspection was performed by the crossed Nicols method. Next, the detected foreign matter in the sample film was observed with transmitted light using an optical microscope, and the maximum diameter of the portion observed as an optically abnormal range was defined as the size of the foreign matter. In addition, when the cavity (void) which exists around a foreign material is observed as an optically abnormal range, it was included in the size of the foreign material. Furthermore, the size of foreign matters was divided into those having a size of 25 μm or more and those having a size of 5 μm or more and less than 25 μm, and the number of foreign matters per each A5 plate was measured.
[0043]
[Example 1]
A polyester composition containing 100 parts by weight of polyethylene terephthalate and 0.05 parts by weight of alumina particles from which aggregated particles of 25 μm or more have been removed as a lubricant by an air classifier is an extruder (a sintered metal between the tip of the extruder and the die). To which the filter made of the product was attached), and melted polyethylene terephthalate was extruded into a film shape, contacted with a rotary cooling drum at 20 ° C., and rapidly cooled to obtain an unstretched film. Next, the unstretched film was sequentially biaxially stretched at the stretch ratio shown in Table 1, and further heat-set under the conditions shown in Table 1 to obtain a biaxially oriented polyethylene terephthalate film having a thickness of 38 μm and a light transmittance of 88%. . Table 1 shows the number of foreign matters in the biaxially oriented polyethylene terephthalate film.
[0044]
Next, on one side of this biaxially oriented polyethylene terephthalate film, a silicone resin coating solution having the following composition was applied at a coating amount (wet) of 8 g / m ² , and dried and cured at 130 ° C. for 30 seconds. A release film having a film thickness of 0.24 μm was obtained.
[0045]
A curing type silicone (KS-847 (H) manufactured by Shin-Etsu Silicone Co., Ltd.), which is subjected to an addition reaction by adding a platinum catalyst to a mixed solution of polydimethylsiloxane and dimethylhydrogensilane, is mixed with methyl ethyl ketone, methyl isobutyl ketone and toluene. Dissolve in a solvent, and blend a silicone resin having the following formula and the above (Q unit) to a solid content ratio of 40% by weight with respect to the curable silicone, to obtain a solution having a total solid content concentration of 3%. Created.
[0046]
This solution was applied to a biaxially stretched polyethylene terephthalate film (thickness 38 μm) at a coating amount of 6 g / m ² (wet), and dried and cured at a heating temperature of 140 ° C. for a heating time of 1 minute to release the mold. Created a film. Table 1 shows the characteristics of this release film.
[0047]
[Chemical formula 2]

[0048]
[Example 2]
A silica filler having an average particle size of 0.5 μm was used in place of the silicone resin, and the silica filler was blended in such a manner that the solid content ratio was 0.3% by weight with respect to the curable silicone. A release film was created. Table 1 shows the characteristics of this release film.
[0049]
[Example 3]
As the curable silicone, separation was performed in the same manner as in Example 1 except that a curable silicone in which 30 mol% of the methyl group (—CH ₃ ) in the main chain polymer was substituted with a phenyl group (—C ₆ H ₅ ) was used. A mold film was created. Table 1 shows the characteristics of this release film.
[0050]
[Example 4]
Example 1 except that a composition in which 90 parts by weight of a mixture of an alkyd resin and a melamine resin was mixed with 10 parts by weight of dimethylpolysiloxane having —SiOH groups at the terminal groups was used instead of the curable silicone and the silicone resin. A release film was prepared in the same manner as described above. Table 1 shows the characteristics of this release film.
[0051]
[Comparative Example 1]
A release film was prepared in the same manner as in Example 1 except that a solution containing no silicone resin was used. Table 1 shows the characteristics of this release film.
[0052]
[Comparative Example 2]
In the same manner as in Example 3, except that a curable silicone in which 10 mol% of methyl groups (—CH ₃ ) in the main chain polymer was substituted with a phenyl group (—C ₆ H ₅ ) was used as the curable silicone. A mold film was created. Table 1 shows the characteristics of this release film.
[0053]
[Comparative Example 3]
As the curable silicone, release was performed in the same manner as in Example 3 except that a curable silicone in which 70 mol% of the methyl group (—CH ₃ ) in the main chain polymer was substituted with a phenyl group (—C ₆ H ₅ ) was used. A mold film was created. Table 1 shows the characteristics of this release film.
[0054]
[Comparative Example 4]
A release film was prepared in the same manner as in Example 4, except that a composition in which 95 parts by weight of a mixture of alkyd resin and melamine resin was blended with 5 parts by weight of dimethylpolysiloxane having —SiOH groups as terminal groups was used. . Table 1 shows the characteristics of this release film.
[0055]
[Comparative Example 5]
A release film was prepared in the same manner as in Example 4 except that a composition in which 35 parts by weight of dimethylpolysiloxane having —SiOH groups at the end groups was blended with 65 parts by weight of a mixture of alkyd resin and melamine resin was used. . Table 1 shows the characteristics of this release film.
[0056]
[Comparative Example 6]
A biaxially stretched polyester film was prepared in the same manner as in Example 1 except that a sintered metal filter was not attached. Further, a release film and a laminate were prepared in the same manner as in Example 1, and each characteristic was evaluated. The results are shown in Table 1.
[0057]
[Table 1]

[0058]
As is clear from the results shown in Table 1, the release films of the present invention shown in Examples 1 to 4 have excellent wettability to water-based paints, peel strength, and residual adhesion rate, and have few foreign substances present in the film. Met.
[0059]
In addition, the preferable range of peeling strength is 5-200 g / cm. When the peel strength is 5 g / cm or less, the resin sheet or the like may be peeled off from the release film when the laminated sheet obtained by laminating the resin sheet or the like on the release film is wound. Moreover, when peeling strength is 200 g / cm or more, when peeling and separating a resin sheet etc. from a lamination sheet and using it, peeling may become difficult, and it is unpreferable.
[0060]
Moreover, the preferable range of a residual adhesive rate is 85% or more. When the residual adhesive rate is less than 85%, for example, when the release film is rolled and stored, the components constituting the release layer are transferred to the surface of the adjacent film (so-called back transfer), and the release is performed. This is not preferable because the layer characteristics may be poor, and the adhesive film surface adhesion characteristics may be poor.
[0061]
【The invention's effect】
Since the release film of the present invention uses a polyester film having a specific maximum surface tension (γLmax) as a release layer and a polyester film with few foreign substances as a base film, it is water-based for various coatings and sheet molding. Excellent wettability when using a coating liquid, excellent releasability from various resin sheets, resin coatings, ceramic sheets, etc., and pinholes when used for molding carrier films such as resin sheets, resin coatings, ceramic sheets, etc. It is possible to obtain a sheet or a film having no such disadvantages.

Claims (3)

A release film in which a release layer having a release layer surface having a maximum surface tension (γ _L max) determined by the following formula (I) of 30 to 50 dyne / cm is provided on at least one side of a polyester film, release film, characterized in that there is no 25μm or foreign matter on the surface product 310.8c m ² during the Ri of the film of the polyester film.
[Expression 1]
γ _L max = 1 / b + γ _C / 2 Formula (I)
[In formula (I), b is a constant determined from the slope of the zisman plot, and γ _C is the critical surface tension. ] ^2. The release film according to claim 1 , wherein the polyester film has 10 or less foreign matters of 5 μm or more and less than 25 μm present in a film per area of 310.8 cm ² . 2. The release film according to claim 1, wherein the release layer contains a polydimethylsiloxane polymer as a main component.