JP5623767B2 - Antistatic releasable polyester film - Google Patents

Description

  The present invention relates to an antistatic releasable polyester film, and more particularly to an antistatic releasable polyester film that uses a silicone compound as a release agent and improves coating film uniformity when used in combination with an antistatic agent.

  Release films based on polyester films are used for various release applications such as cards, labels, printing, adhesives, ceramic molding, and transfer foils. Usually, the release film which uses such a polyester film as a base material is produced by applying and laminating a substance exhibiting a release function on the surface of the polyester film. Silicone compounds are often used as substances that exhibit a mold release function. However, the silicone compound film is easily charged without leakage of charge due to the main chain bond and the three-dimensional structure of the silicone. In other words, the -Si-O-Si- bond in the main chain is basically σ bond but has ionicity as compared to the -C-C- bond, and is charged like a conjugated double bond. Cannot be delocalized. Further, the two methyl groups bonded to Si face the outside of the main chain to form a hydrophobic field, and it is extremely difficult to leak charges through moisture and impurity ions in the air. A film coated with such a silicone compound naturally has high chargeability, and the films tend to block each other, and thus various obstacles occur. Therefore, an antistatic function is imparted to a release film containing a silicone compound.

  First, a release film having an antistatic function has been proposed by laminating a coating material in which a silicone compound and a compound having an antistatic function are mixed on the film surface (Patent Document 1). In the case of this method, a compound having an antistatic function is a compound that is difficult to mix with a silicone compound, resulting in a non-uniform coating film, which may result in unstable mold release performance or antistatic performance.

Therefore, a method has been proposed in which a silicone compound and a compound having an antistatic function are not mixed. For example, it has been proposed to laminate an antistatic coating film on the opposite surface of the silicone compound coating film (Patent Documents 2 and 3). However, with this method, the coating process is performed twice, so that it takes time and the coating process is performed twice, so that scratches and adhesion of foreign matter to the film surface tend to increase. As another method, it has been proposed that a release layer is applied and laminated on an antistatic coating film to impart an antistatic function (Patent Document 4). However, in the method of laminating the release layer on the antistatic coating film, the coating process is complicated, and it is difficult to obtain a uniform coating film because a highly accurate coating technique is required.
Furthermore, a release film having an antistatic function obtained by chemically mixing a silicone compound and a compound having an antistatic function has also been proposed (Patent Document 5). With this method, the coating film becomes uniform, but since it becomes a special compound, it may not be possible to produce this compound stably.

On the other hand, various antistatic agents for thermoplastic polymers that have improved heat resistance and can be reused have been proposed (Patent Documents 6 and 7), and antistatic agents using such antistatic agents have been proposed. A conductive polyester film has been proposed (Patent Documents 8 and 9). However, in these Patent Documents 6 to 9, no examination is made from the viewpoint of imparting release performance.
Thus, for a releasable polyester film using a silicone compound, it can be easily and stably produced when a silicone release agent and an antistatic agent are used in combination, and the coating film uniformity is high, and the releasability, The present condition is that a coating layer having a stable antistatic quality is required.

JP-A-6-116426 JP-A-9-277451 Japanese Patent Laid-Open No. 10-315373 JP 2000-52495 A JP-A-11-188813 JP 2005-350517 A JP 2006-2074 A JP 2008-55621 A JP 2008-45085 A

  The object of the present invention is to solve the problems of the prior art, use a silicone compound as a release agent for a releasable polyester film, and easily and stably when such a release agent and an antistatic agent are used in combination. An object of the present invention is to provide an antistatic releasable polyester film that can be produced, has high coating uniformity, and has stable releasability and antistatic properties.

  As a result of intensive studies to solve the above problems, the present inventors have included a polyoxyalkylene chain as an antistatic agent that imparts antistatic properties to a releasable polyester film using a silicone compound as a releasing agent. When the cationic polymer is used, the compatibility between the release agent and the antistatic agent is remarkably improved compared to the conventionally used cationic polymer containing no polyoxyalkylene chain, and excellent coating uniformity is obtained. As a result, the haze of the antistatic release layer is improved and the coating spots are less noticeable. As a result, these agents can be used together in the same coating film, and can be produced easily and stably. Since the mold agent and the antistatic agent are uniformly dispersed, it has been found that both the mold release property and the antistatic property are stable, and the present invention has been completed.

（上式（１）中、Ｒ ¹ およびＲ ² はそれぞれＨまたは炭素数１〜３の飽和炭化水素基であり、Ｒ ³ は炭素数１〜１０のアルキレン基であり、Ｒ ⁴ およびＲ ⁵ はそれぞれ炭素数１〜３の飽和炭化水素基であり、Ｒ ⁶ はＨまたは炭素数２〜４のヒドロキシアルキル基であり、Ｙ ^- はハロゲンイオン、ナイトレートイオン、サルフェートイオン、アルキルサルフェートイオン、スルホネートイオンまたはアルキルスルホネートイオンである）

（上式（２）中、Ｒ ⁷ およびＲ ⁸ はそれぞれＨまたは炭素数１〜３の飽和炭化水素基であり、Ｒ ⁹ は炭素数１〜１０のアルキレン基であり、Ｒ ¹⁰ およびＲ ¹¹ はそれぞれ炭素数１〜３の飽和炭化水素基であり、Ｒ ¹² はＨまたは炭素数２〜４のヒドロキシアルキル基であり、Ｚ ^- はハロゲンイオン、ナイトレートイオン、サルフェートイオン、アルキルサルフェートイオン、スルホネートイオンまたはアルキルスルホネートイオンである）

（上式（３）中、Ｒ ¹³ およびＲ ¹⁴ はそれぞれＨまたは炭素数１〜３の飽和炭化水素基であり、Ａ ₁ は分子中に合計２〜２０個のオキシエチレン単位及び／又はオキシプロピレン単位で構成されたポリオキシアルキレン基を有するポリオキシアルキレンジオールから１つの水酸基を除いた残基をそれぞれ表わす）

（上式（４）中、Ｒ ¹⁵ およびＲ ¹⁶ はそれぞれＨまたは炭素数１〜３の飽和炭化水素基であり、Ａ ₂ は分子中に合計２〜２０個のオキシエチレン単位及び／又はオキシプロピレン単位で構成されたポリオキシアルキレン基を有するポリオキシアルキレンジオールから１つの水酸基を除いた残基をそれぞれ表わす）
該離型剤がシリコーン化合物であり、含有量が帯電防止離型層の重量を基準として２０重量％以上である帯電防止離型性ポリエステルフィルムによって達成される。 That is, an object of the present invention is an antistatic releasable polyester film having a polyester film and an antistatic layer containing an antistatic agent and a release agent on at least one surface thereof, wherein the antistatic agent has a polyoxyalkylene chain. A cationic polymer containing
The cationic polymer is formed from a structural unit A formed from a monomer represented by the following formula (1) or the following formula (2), and a monomer represented by the following formula (3) or the following formula (4). Comprising the structural unit B

(In the above formula (1), R ¹ and R ² are each H or a saturated hydrocarbon group having 1 to ³ carbon atoms , R ³ is an alkylene group having 1 to 10 carbon atoms, and R ⁴ and R ⁵ are Each is a saturated hydrocarbon group having 1 to 3 carbon atoms, R ⁶ is H or a hydroxyalkyl group having 2 to 4 carbon atoms, and Y ⁻ is a halogen ion, nitrate ion, sulfate ion, alkyl sulfate ion, or sulfonate ion. Or an alkyl sulfonate ion)

(In the above formula (2), R ⁷ and R ⁸ are each H or a saturated hydrocarbon group having 1 to 3 carbon atoms, R ⁹ is an alkylene group having 1 to 10 carbon atoms, and R ¹⁰ and R ¹¹ are Each is a saturated hydrocarbon group having 1 to 3 carbon atoms, R ¹² is H or a hydroxyalkyl group having 2 to 4 carbon atoms, and Z ⁻ is a halogen ion, a nitrate ion, a sulfate ion, an alkyl sulfate ion, or a sulfonate ion. Or an alkyl sulfonate ion)

(In the above formula (3), R ¹³ and R ¹⁴ are each H or a saturated hydrocarbon group having 1 to 3 carbon atoms, and A ₁ is a total of 2 to 20 oxyethylene units and / or oxypropylene in the molecule. Each represents a residue obtained by removing one hydroxyl group from a polyoxyalkylene diol having a polyoxyalkylene group composed of units)

(In the above formula (4), R ¹⁵ and R ¹⁶ are each H or a saturated hydrocarbon group having 1 to 3 carbon atoms, and A ₂ is a total of 2 to 20 oxyethylene units and / or oxypropylene in the molecule. Each represents a residue obtained by removing one hydroxyl group from a polyoxyalkylene diol having a polyoxyalkylene group composed of units)
Release agent is a silicone compound der is, content is achieved by Ru der 20 wt% or more antistatic releasing polyester film based on the weight of the antistatic release layer.

（上式（５）中、Ｒ¹⁷およびＲ¹⁸はそれぞれＨまたは炭素数１〜３の飽和炭化水素基であり、Ｒ¹⁹はＨまたは炭素数１〜６の飽和炭化水素基をそれぞれ表わす）
カチオンポリマーの全構成単位を基準として構成単位Ａを６０モル％以上９９．９モル％以下、構成単位Ｂを０．１モル％以上４０モル％以下の範囲で含んでなること、
シリコーン化合物がポリジメチルシロキサン、エポキシ基含有シリコーン、アミノ基含有シリコーン、および炭素数６以上の炭化水素基を有するシリコーンからなる群から選ばれる少なくとも１種であること、の少なくともいずれか１つを具備するものも包含する。
Moreover, the antistatic releaseable polyester film of the present invention is as a preferred embodiment,
The peel strength of the pressure-sensitive adhesive tape by the measurement method described later on the surface of the antistatic release layer is 300 g / 10 mm or less,
The cationic polymer further comprises a structural unit C formed from a monomer represented by the following formula (5):

(In the above formula (5), R ¹⁷ and R ¹⁸ are each H or a saturated hydrocarbon group having 1 to 3 carbon atoms, and R ¹⁹ is H or a saturated hydrocarbon group having 1 to 6 carbon atoms, respectively)
Comprising from 60 mol% to 99.9 mol% of the structural unit A and 0.1 mol% to 40 mol% of the structural unit B based on the total structural units of the cationic polymer;
The silicone compound is at least one selected from the group consisting of polydimethylsiloxane, epoxy group-containing silicone, amino group-containing silicone, and silicone having a hydrocarbon group having 6 or more carbon atoms. It also includes what to do.

  The antistatic releasable polyester film of the present invention has high coating uniformity, can be produced easily and stably, and has stable releasability and antistatic properties. It can be suitably used for various applications requiring releasability such as printing, adhesive, ceramic molding, and transfer foil.

Hereinafter, the present invention will be described in detail.
[Polyester film]
The polyester constituting the polyester film of the present invention is a linear saturated polyester synthesized from an aromatic dibasic acid or an ester-forming derivative thereof and a diol or an ester-forming derivative thereof. Specific examples of such polyester include polyethylene terephthalate, polyethylene isophthalate, polybutylene terephthalate, poly (1,4-cyclohexylenedimethylene terephthalate), and polyethylene-2,6-naphthalate.

  The polyester may be a copolymer having one of these polyesters as a main component, or may be a blend. Here, the “main component” is 80 mol% or more based on the number of moles of the repeating unit of the polyester. The ratio of the main component is preferably 85 mol% or more, and more preferably 90 mol% or more. The copolymer component or blend component is 20 mol% or less, preferably 15 mol% or less, more preferably 10 mol% or less, based on the number of moles of the repeating unit of the polyester. Polyethylene terephthalate is particularly preferred as the polyester because it has a good balance between mechanical properties and moldability.

The polyester film may contain, for example, inorganic or organic lubricants such as silicon dioxide, calcium carbonate, kaolin, and silicone particles, colorants, antistatic agents, and antioxidants.
The polyester film can be produced, for example, by the following method. That is, polyester is melt-extruded into a film shape, cooled and solidified with a casting drum to form an amorphous unstretched film, and the longitudinal direction (hereinafter sometimes referred to as a continuous film-forming direction, the longitudinal direction, and the MD direction) and the lateral direction (hereinafter referred to as the “non-stretched film”). , Sometimes referred to as the width direction and the TD direction). Stretching in the machine direction is, for example, at a temperature of 60 to 130 ° C., preferably 90 to 125 ° C., and is stretched by 2.0 to 4.0 times, preferably 2.5 to 3.5 times. Stretching in the transverse direction is, for example, stretched at a temperature of 60 to 130 ° C., preferably 90 to 125 ° C., and 2.0 to 4.0 times, preferably 3.0 to 4.0 times. The area magnification after biaxial stretching is preferably 13 or less.

In addition, it is preferable to perform a heat setting process after extending | stretching a film. The heat setting treatment is preferably performed within a time period of 1 to 30 seconds within a temperature higher than the final stretching temperature and not higher than the melting point. For example, in the case of a polyethylene terephthalate film, it is preferable to select and heat-set at a temperature of 150 to 250 ° C. and a time of 2 to 30 seconds. At that time, it may be performed under a limited contraction or expansion within 20%, or under a constant length, or may be performed in two or more stages.
The thickness of the polyester film is preferably 12 to 100 μm, and more preferably 25 to 75 μm, in order to obtain necessary strength from the viewpoints of handling properties and moldability.

[Antistatic release layer]
The antistatic release polyester film of the present invention has an antistatic release layer containing an antistatic agent and a release agent on at least one surface of the polyester film, and the antistatic agent contains a polyoxyalkylene chain. And the release agent is a silicone compound.

(Cationic polymer)
As a cationic polymer containing a polyoxyalkylene chain, for example, the structural unit A formed from a monomer represented by the following formula (1) or the following formula (2), and the following formula (3) or the following formula (4) And a cationic polymer containing the structural unit B formed from the represented monomer.

（上式（１）中、Ｒ¹およびＲ²はそれぞれＨまたは炭素数１〜３の飽和炭化水素基であり、Ｒ³は炭素数１〜１０のアルキレン基であり、Ｒ⁴およびＲ⁵はそれぞれ炭素数１〜３の飽和炭化水素基であり、Ｒ⁶はＨまたは炭素数２〜４のヒドロキシアルキル基であり、Ｙ^-はハロゲンイオン、ナイトレートイオン、サルフェートイオン、アルキルサルフェートイオン、スルホネートイオンまたはアルキルスルホネートイオンである）

(In the above formula (1), R ¹ and R ² are each H or a saturated hydrocarbon group having 1 to ³ carbon atoms, R ³ is an alkylene group having 1 to 10 carbon atoms, and R ⁴ and R ⁵ are Each is a saturated hydrocarbon group having 1 to 3 carbon atoms, R ⁶ is H or a hydroxyalkyl group having 2 to 4 carbon atoms, and Y ⁻ is a halogen ion, nitrate ion, sulfate ion, alkyl sulfate ion, or sulfonate ion. Or an alkyl sulfonate ion)

（上式（２）中、Ｒ⁷およびＲ⁸はそれぞれＨまたは炭素数１〜３の飽和炭化水素基であり、Ｒ⁹は炭素数１〜１０のアルキレン基であり、Ｒ¹⁰およびＲ¹¹はそれぞれ炭素数１〜３の飽和炭化水素基であり、Ｒ¹²はＨまたは炭素数２〜４のヒドロキシアルキル基であり、Ｚ^-はハロゲンイオン、ナイトレートイオン、サルフェートイオン、アルキルサルフェートイオン、スルホネートイオンまたはアルキルスルホネートイオンである）

(In the above formula (2), R ⁷ and R ⁸ are each H or a saturated hydrocarbon group having 1 to 3 carbon atoms, R ⁹ is an alkylene group having 1 to 10 carbon atoms, and R ¹⁰ and R ¹¹ are Each is a saturated hydrocarbon group having 1 to 3 carbon atoms, R ¹² is H or a hydroxyalkyl group having 2 to 4 carbon atoms, and Z ⁻ is a halogen ion, a nitrate ion, a sulfate ion, an alkyl sulfate ion, or a sulfonate ion. Or an alkyl sulfonate ion)

（上式（３）中、Ｒ¹³およびＲ¹⁴はそれぞれＨまたは炭素数１〜３の飽和炭化水素基であり、Ａ₁は分子中に合計２〜２０個のオキシエチレン単位及び／又はオキシプロピレン単位で構成されたポリオキシアルキレン基を有するポリオキシアルキレンジオールから１つの水酸基を除いた残基をそれぞれ表わす）

(In the above formula (3), R ¹³ and R ¹⁴ are each H or a saturated hydrocarbon group having 1 to 3 carbon atoms, and A ₁ is a total of 2 to 20 oxyethylene units and / or oxypropylene in the molecule. Each represents a residue obtained by removing one hydroxyl group from a polyoxyalkylene diol having a polyoxyalkylene group composed of units)

（上式（４）中、Ｒ¹⁵およびＲ¹⁶はそれぞれＨまたは炭素数１〜３の飽和炭化水素基であり、Ａ₂は分子中に合計２〜２０個のオキシエチレン単位及び／又はオキシプロピレン単位で構成されたポリオキシアルキレン基を有するポリオキシアルキレンジオールから１つの水酸基を除いた残基をそれぞれ表わす）

(In the above formula (4), R ¹⁵ and R ¹⁶ are each H or a saturated hydrocarbon group having 1 to 3 carbon atoms, and A ₂ is a total of 2 to 20 oxyethylene units and / or oxypropylene in the molecule. Each represents a residue obtained by removing one hydroxyl group from a polyoxyalkylene diol having a polyoxyalkylene group composed of units)

  Specific examples of the monomer represented by the formula (1) forming the structural unit A include acryloylaminoethyltrimethylammonium methylsulfonate, acryloylaminopropyldimethylammonium ethylsulfonate, acryloylaminopropyl 2-hydroxyethyldimethylammonium. Examples thereof include nitrate, acryloylaminopropyltrimethylammonium nitrate, methacryloylaminobutyltrimethylammonium methylsulfonate, methacryloylaminohexyldi (2-hydroxyethyl) ammonium nitrate, and the like.

  Specific examples of the monomer represented by the formula (2) forming the structural unit A include acryloyloxyethyltrimethylammonium methylsulfonate, acryloyloxypropyldimethylammonium ethylsulfonate, acryloyloxypropyl 2-hydroxyethyldimethylammonium. Examples thereof include nitrate, acryloyloxypropyltrimethylammonium nitrate, methacryloyloxybutyltrimethylammonium methylsulfonate, methacryloyloxyhexyl di (2-hydroxyethyl) ammonium nitrate, and the like.

  Specific examples of the monomer represented by the formula (3) forming the structural unit B include polyoxyethylene acrylate, polyoxypropylene acrylate, oxyethylene oxypropylene acrylate, polyoxyethylene oxypropylene acrylate, Oxyethylene polyoxypropylene acrylate, polyoxyethylene polyoxypropylene acrylate, polyoxyethylene methacrylate, polyoxypropylene methacrylate, oxyethylene oxypropylene methacrylate, polyoxyethylene oxypropylene methacrylate, oxyethylene polyoxymethacrylate methacrylate Propylene, polyoxyethylene methacrylate, polyoxypropylene, crotonic acid polyoxypropylene, crotonic acid oxyethyleneoxypropylene, crotonic acid polyoxy Chi Ren oxypropylene, crotonic acid polyoxypropylene, polyoxyethylene polyoxypropylene etc. crotonic acid.

  Specific examples of the monomer represented by the formula (4) that forms the structural unit B include α-allyl-ω-hydroxy (polyoxyethylene), α-allyl-ω-hydroxy (polyoxypropylene), α-allyl. -Ω-hydroxy (oxyethyleneoxypropylene), α-allyl-ω-hydroxy (polyoxyethyleneoxypropylene), α-allyl-ω-hydroxy (polyoxyethylene polyoxypropylene), α-methallyl-ω-hydroxy ( Polyoxyethylene), α-methallyl-ω-hydroxy (polyoxypropylene), α-methallyl-ω-hydroxy (oxyethyleneoxypropylene), α-methallyl-ω-hydroxy (polyoxyethyleneoxypropylene), α-methallyl -Ω-hydroxy (polyoxyethylene polyoxypropylene) and the like It is.

When the cationic polymer of the present invention contains the structural unit A containing a cationic component composed of the monomer represented by the formula (1) or (2) as an essential component, the function as an antistatic agent is exhibited. .
Further, the cationic polymer of the present invention contains a structural unit B containing a polyoxyalkylene chain composed of a monomer represented by the formula (3) or (4) as an essential component, so that it is compatible with a silicone compound. And improved coating uniformity when antistatic agent and silicone compound are used in the same coating, and haze of antistatic release layer is improved, so that coating spots are less likely to appear. Since the release agent and the antistatic agent are uniformly dispersed, the quality of both the release property and the antistatic property becomes stable. The polyoxyalkylene chain in the structural unit B is a repeating number of 2 to 20, more preferably 5 to 15, and particularly preferably 8 to 15.

The structural unit A and the structural unit B preferably include the structural unit A in a range of 60 mol% or more and 99.9 mol% or less based on all the structural units of the cationic polymer. It is preferable to contain in mol% or more and 40 mol% or less. Further, the content of the structural unit A is more preferably 65 mol% or more and 90 mol% or less, further preferably 65 mol% or more and 80 mol% or less, and the content of the structural unit B is more preferably 10 mol% or more and 35 mol% or less. The mol% or less, more preferably 20 mol% or more and 35 mol% or less.
When the structural unit A is less than the lower limit, sufficient antistatic performance may not be exhibited. Further, when the structural unit A exceeds the upper limit value, the structural unit B is relatively decreased, so that the compatibility with the silicone compound is deteriorated, and the coating film uniformity may be decreased. When the structural unit B is less than the lower limit value, the silicone compound and the cationic polymer are not sufficiently compatible with each other, so that phase separation occurs, the coating film is difficult to be uniform, and the mold release property and antistatic property are improved. Variations are likely to occur. Further, when the structural unit B exceeds the upper limit value, the heat resistance and moisture resistance of the cationic polymer are lowered, so that the blocking resistance of the coating film may be lowered.

（上式（５）中、Ｒ¹⁷およびＲ¹⁸はそれぞれＨまたは炭素数１〜３の飽和炭化水素基であり、Ｒ¹⁹はＨまたは炭素数１〜６の飽和炭化水素基をそれぞれ表わす） It is preferable that the cationic polymer of the present invention further includes a structural unit C formed from a monomer represented by the following formula (5).

(In the above formula (5), R ¹⁷ and R ¹⁸ are each H or a saturated hydrocarbon group having 1 to 3 carbon atoms, and R ¹⁹ is H or a saturated hydrocarbon group having 1 to 6 carbon atoms, respectively)

When the cationic polymer of the present invention further contains the structural unit C, the cohesive force of the resin itself is improved and the coating film can be strengthened.
Specific examples of the monomer represented by the formula (5) forming the structural unit C include N-methylol acrylamide, N-methylol methacrylamide, N-methoxymethyl acrylamide, N-ethoxymethyl acrylamide, N-butoxymethyl acrylamide, N-tertiary butyloxymethyl acrylamide, N-hexyloxymethyl acrylamide, N-methoxymethyl methacrylamide, N-ethoxymethyl methacrylamide, N-butoxymethyl methacrylamide, N-tertiary butyloxymethyl methacrylamide, N-hexyl Examples include oxymethyl methacrylamide, among which N-methylol acrylamide, N-methoxymethyl acrylamide, and N-butoxymethyl acrylamide are preferable.

  When the cationic polymer of the present invention includes the structural unit C formed from the monomer represented by the formula (5), the content of the structural unit C is 1 mol% or more and 30 mol based on the total structural unit of the cationic polymer. % Or less, and more preferably 5 mol% or more and 25 mol% or less. When content of the structural unit C is less than a lower limit, the cohesion force of a coating film may fall. On the other hand, when the content of the structural unit C exceeds the upper limit, the film forming property of the cationic polymer itself is deteriorated, which may affect the appearance of the coating film.

A structural unit D of a general vinyl copolymer may be introduced into the cationic polymer of the present invention as necessary for flexibility, hardness adjustment, water dispersion and the like. Specific examples include alkyl acrylate, alkyl methacrylate, styrene, α-methylstyrene, and the like. Here, examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, a 2-ethylhexyl group, and a cyclohexyl group.
When the structural unit D of these general vinyl copolymers is introduced, it is preferably contained in the range of 1 mol% to 40 mol%, more preferably 5 mol%, based on the total structural units of the cationic polymer. It is the range of 30 mol% or less. These are examples, and the structural unit D is not limited to these.

  The cationic polymer of the present invention preferably has a number average molecular weight of 5,000 to 1,000,000, and more preferably 7,000 to 100,000. If the number average molecular weight of the cationic polymer is less than the lower limit, the antistatic property may not be sufficient. In addition, when the number average molecular weight of the cationic polymer exceeds the upper limit, the coating film may be difficult to be uniform.

  The cationic polymer of the present invention can be obtained by radical copolymerization. The radical copolymerization itself can be carried out by a known method, usually an aqueous solution using water or a mixed solvent of water and a water-soluble organic solvent. For example, each constituent unit is dissolved in water in a predetermined amount to prepare an aqueous solution containing a total of 10 to 45% by weight, and then a radical initiator is added thereto under a nitrogen gas atmosphere, and the mixture is added at 50 to 80 ° C. for 4 to 8 Allow time radical polymerization reaction. The radical initiator to be used is not particularly limited as long as it decomposes at a polymerization reaction temperature and generates radicals, but a water-soluble radical initiator is preferably used. Examples of the water-soluble radical initiator include potassium persulfate, ammonium persulfate, hydrogen peroxide, 2,2-azobis (2-amidinopropane) dihydrochloride, and the like. These can also be used as a redox initiator in combination with a reducing substance such as sulfite or L-ascorbic acid, or an amine. Moreover, when setting it as emulsion polymerization, it can implement similarly by using an appropriate surfactant.

(Silicone compound)
In the present invention, a silicone compound is used to develop releasability. Examples of the silicone compound include polydimethylsiloxane, epoxy group-containing silicone, amino group-containing silicone, and silicone having a hydrocarbon group having 6 or more carbon atoms. It is preferable to use at least one selected from the group consisting of
By using a silicone compound as a release agent, the release property is high in any environment and can be used for a wide variety of applications. Among these silicone compounds, especially polydimethylsiloxane, silicone compounds such as epoxy group-containing silicone or amino group-containing silicone are often used as mold release agents, but are difficult to mix with cationic polymers, and the polyoxyalkylene of the present invention The effect of improving the uniformity of the coating film is particularly high when a cationic polymer containing a chain is used. In particular, a silicone compound having a polar component such as an epoxy group-containing silicone or an amino group-containing silicone is more compatible with the cationic polymer containing the polyoxyalkylene chain of the present invention, and the coating film uniformity is improved. To preferred.

  As the polydimethylsiloxane, polydimethylsiloxane having a viscosity at 25 ° C. in the range of 100 to 100,000 centistokes is preferable. If the viscosity is lower than 100 centistokes, the releasability may not be sufficient. On the other hand, when the viscosity is higher than 100,000 centistokes, the viscosity is high and the molecular weight is also large, so that the compatibility with the cationic polymer may be lowered.

  As epoxy groups of epoxy group-containing silicones, glycidoxyalkyl groups such as γ-glycidoxypropyl group, β-glycidoxyethyl group, γ-glycidoxy-β-methyl-propyl group, 2-glycidoxycarbonyl-ethyl And a glycidoxycarbonylalkyl group such as 2-glycidoxycarbonyl-propyl group. The viscosity is preferably in the same range as polydimethylsiloxane.

  As the amino group of the amino group-containing silicone, primary aminoalkyl group such as 3-aminopropyl group, 3-amino-2-methyl-propyl group, 2-aminoethyl group, N- (2-aminoethyl) -3-amino Examples thereof include organic groups having primary and secondary aminoalkyl groups such as propyl group and N- (2-aminoethyl) -2-aminoethyl group. The viscosity is preferably in the same range as polydimethylsiloxane.

  Examples of the silicone having a hydrocarbon group having 6 or more carbon atoms include alkyl-modified silicones having 6 or more carbon atoms, aralkyl-modified silicones having 6 or more carbon atoms, alkylaralkyl co-modified silicones having 6 or more carbon atoms, and aryl-modified silicones. When silicone having a hydrocarbon group having 6 or more carbon atoms is used, wettability can be improved while maintaining the release performance of the surface of the antistatic release layer.

（式（６）中、Ｒ²⁰は炭素数１〜５の飽和または不飽和の１価炭化水素基、Ｒ²¹は炭素数６〜２０の飽和または不飽和の１価炭化水素基、Ｒ²²はＲ²⁰又はＲ²¹をそれぞれ表わし、ｍは０〜５００の整数、ｎは１〜５００の整数を表わす。） Examples of the silicone having a hydrocarbon group having 6 or more carbon atoms include compounds represented by the following formula (6).

(In the formula (6), R ²⁰ is a saturated or unsaturated monovalent hydrocarbon group having 1 to 5 carbon atoms, R ²¹ is a saturated or unsaturated monovalent hydrocarbon group having 6 to 20 carbon atoms, and R ²² is R represents R ²⁰ or R ²¹ , m represents an integer of 0 to 500, and n represents an integer of 1 to 500.)

In the above formula, R ²⁰ is the same or different C 1-5 saturated or unsaturated monovalent hydrocarbon group, specifically, methyl group, ethyl group, propyl group, butyl group, pentyl group, And saturated alicyclic hydrocarbon groups such as a cyclopentyl group, and a methyl group is particularly preferable.

R ²¹ is the same or different monovalent or unsaturated monovalent hydrocarbon group having 6 to 20 carbon atoms, and examples thereof include an alkyl group, specifically, a hexyl group, a heptyl group, an octyl group. Nonyl group, decyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, heptadecyl group, octadecyl group, nonadecyl group, and eicosyl group are exemplified, and dodecyl group and tetradecyl group are particularly preferable. Examples of R ²¹ other than an alkyl group include an aralkyl group. Specific examples include a benzyl group, a 4-methylbenzyl group, a p-methoxybenzyl group, a diphenylmethyl group, a 2-phenylethyl group, and a 2-phenylpropyl group. , 3-phenylpropyl group is exemplified, and 2-phenylpropyl group is particularly preferable. Another example of R ^{21 is} an aryl group, and a phenyl group is particularly preferable.
Among these, a phenyl group having better compatibility with the antistatic agent can be most preferably used as the hydrocarbon group having 6 to 20 carbon atoms of R ²¹ .

(Surfactant)
The silicone component used in the present invention is preferably used in the form of an aqueous dispersion or an emulsion from the viewpoint of ease of handling during coating and the working environment. In order to obtain a good aqueous dispersion and emulsion form, the use of a surfactant is preferred, and a nonionic surfactant is particularly preferred because of its dispersion stability with other components of the coating liquid.

(Crosslinking agent)
In order to improve the cohesive strength of the coating film, it is preferable to further add a crosslinking agent to the antistatic release layer. Examples of the crosslinking agent include epoxy compounds, oxazoline compounds, melamine compounds, and isocyanate compounds, and other coupling agents can also be used. Epoxy compounds and oxazoline compounds are preferably used because of easy handling and the pot life of the coating liquid, and a coupling agent is also preferably used.

(Composition ratio of antistatic release layer)
The proportion of each additive in the antistatic release layer of the present invention is such that the cationic polymer of the present invention, that is, the antistatic agent is 35 to 90% by weight based on the weight of the antistatic release layer, and the release agent comprises a silicone compound. Is preferably 1 to 50% by weight, and the surfactant is preferably 0 to 15% by weight.
The content of the antistatic agent is more preferably 35 to 70% by weight, and further preferably 35 to 65% by weight. The content of the silicone release agent is more preferably 10 to 40% by weight, and further preferably 20 to 30% by weight. The content of the surfactant is more preferably 5 to 12% by weight.

  If the antistatic agent comprising the cationic polymer of the present invention is less than the lower limit value, the antistatic performance is insufficient, the adhesion of dust and the like in the processing step increases, and the occurrence of defects may increase, while the upper limit When the value is exceeded, the content of the silicone component is relatively lowered, and the release performance may be lowered. Moreover, if the release agent which consists of silicone compounds is less than a lower limit, mold release performance may fall, and on the other hand, when it exceeds an upper limit, coating-film uniformity may fall. When the surfactant is less than the lower limit value, the uniform coating property may be lowered. On the other hand, when the upper limit value is exceeded, foaming is likely to occur and coating defects due to foam may easily occur.

  When the antistatic release layer further contains a crosslinking agent, the content of the crosslinking agent is preferably 1 to 30% by weight, and more preferably 2 to 20% by weight. In addition, when the crosslinking agent is included, the content of the crosslinking agent is less than the lower limit value, the coating film cohesive force may be reduced, and the scratch resistance may be reduced. The film-forming property may decrease and the coating appearance may decrease.

(Method of forming antistatic release layer)
In the present invention, the composition used for coating the antistatic release layer is an aqueous coating solution such as an aqueous solution, aqueous dispersion or emulsion (hereinafter referred to as an aqueous coating solution) in order to form a coating layer. It is preferable to be used in the form of
The solid content concentration of the aqueous coating solution used in the present invention is usually 20% by weight or less, preferably 1 to 10% by weight, based on the weight of the coating solution. If the solid content concentration is less than the lower limit, the applicability to the polyester film may be insufficient. Moreover, when solid content concentration exceeds an upper limit, the stability of a coating liquid and the external appearance of a coating layer may fall.

Application of the aqueous coating solution to the polyester film can be carried out at any stage, but it is preferably carried out during the production process of the polyester film, and is further applied to the polyester film before the completion of orientational crystallization. Is preferred.
Here, the polyester film before the crystal orientation is completed is an unstretched film, a uniaxially oriented film in which the unstretched film is oriented in either the longitudinal direction or the transverse direction, and further in two directions, the longitudinal direction and the transverse direction. And the like that have been oriented at a low magnification (biaxially stretched film before being finally re-stretched in the machine direction or the transverse direction to complete orientation crystallization). In particular, it is preferable to apply the aqueous coating liquid of the above composition to an unstretched film or a uniaxially stretched film oriented in one direction, and perform longitudinal stretching and / or lateral stretching and heat setting as it is.

When an aqueous coating solution is applied to a film, the film surface is subjected to a physical treatment such as a corona surface treatment, a flame treatment, a plasma treatment or the like as a pretreatment for improving the coatability, or as described above together with the composition. It is preferable to use a surfactant in combination.
As a coating method, any known coating method can be applied. For example, a roll coating method, a gravure coating method, a roll brush method, a spray coating method, an air knife coating method, an impregnation method, a curtain coating method and the like can be used alone or in combination.

(Thickness of antistatic release layer)
The thickness of the antistatic release layer is preferably 0.01 to 0.1 μm, more preferably 0.01 to 0.06 μm, as the thickness after drying. If the thickness of the antistatic release layer is less than the lower limit value, the antistatic property and release property may not be sufficiently developed, and if the upper limit value is exceeded, it is necessary to increase the coating liquid or increase the coating amount. Therefore, it tends to be difficult to apply, and the coatability may be uneven.

  Hereinafter, the present invention will be described in more detail with reference to examples. Various physical properties were evaluated by the following methods. Moreover, wt% represents weight%.

(1) Haze of coating layer (haze of antistatic release layer)
According to JIS K7136, the haze measuring device (NDH-2000) by Nippon Denshoku Industries Co., Ltd. was used, and the coating layer haze was measured from the following formula (I).
Coating layer haze = film haze-coating layer uncoated film haze (I)
A +: Less than 0.1% A: Less than 0.1-0.4% B: Less than 0.4-0.8% C: 0.9% or more In this evaluation, up to A satisfies practical performance.

(2) Uniformity of coating layer The light of a three-wavelength fluorescent lamp is applied to the film surface, and the coating state is observed with regular reflection light.
A +: The coating layer is uniform.
A: There are extremely weak spots.
B: There are weak spots.
C: There are strong spots.
In this evaluation, up to A satisfies practical performance.

(3) Antistatic property The surface resistivity of the antistatic layer surface of the sample film is 1 at an applied voltage of 100 V under the conditions of a measurement temperature of 23 ° C. and a measurement humidity of 60% using a specific resistance measuring device manufactured by Takeda Riken. Measure the surface resistivity (Ω / □) after a minute. The surface resistivity is preferably 1 × 10 ¹³ [Ω / □] or less, more preferably 1 × 10 ¹² or less.

(4) Releasability Adhesive tape (product name “No. 31B” manufactured by Nitto Denko Corporation) is pasted on the antistatic release surface, pressed with a 5 kg pressure roller and left for 20 hours, and then the antistatic release surface. The peel strength between the adhesive tape and the adhesive tape was measured with a tensile tester. In addition, the preferable range of peeling strength is 300 g / 10mm or less. If the peel strength is greater than 300 g / 10 mm, it may be difficult to separate the resin sheet or the like from the laminated sheet to which the release film is attached.

(5) Coating layer thickness The film is fixed with an embedding resin, the cross section is cut with a microtome, stained with 2% osmic acid at 60 ° C. for 2 hours, and coated using a transmission electron microscope (JEM2010, manufactured by JEOL Ltd.). The layer thickness was measured.

[Examples 1-7, Comparative Examples 1-3]
Molten polyethylene terephthalate ([η] = 0.63 dl / g, Tg = 78 ° C.) containing 0.01 wt% of silicon oxide particles having an average particle diameter of 1.5 μm is extruded from a die and cooled by a cooling drum in a conventional manner. The film was stretched 3.4 times in the longitudinal direction, and then a coating solution (3 wt% coating solution) composed of the coating layer constituents shown in Table 1 was uniformly coated on a roll coater.
Subsequently, this coated film was subsequently dried at 110 ° C., stretched 3.7 times in the transverse direction at 140 ° C., and further heat-set at 230 ° C. to form a coating film (antistatic release layer) shown in Table 1. A biaxially stretched polyester film (thickness: 38 μm) was obtained. These example films were capable of forming a layer having both antistatic properties and releasability functions in a single step, and high productivity was obtained.

（上式（１）中、Ｒ^１、Ｒ^２はそれぞれＨであり、Ｒ^３は炭素数が３のアルキレン基であり、Ｒ^４、Ｒ^５はそれぞれ炭素数が１の飽和炭化水素基であり、Ｒ^６は炭素数が３のヒドロキシアルキル基であり、Ｙ⁻はメチルスルホネートイオンである） Antistatic agent 1: A copolymer having a structure represented by the following formula (1) composed of 70 mol% / methoxypolyethylene glycol (n = 9) methacrylate 30 mol%.

(In the above formula (1), R ¹ and R ² are each H, R ³ is an alkylene group having 3 carbon atoms, and R ⁴ and R ⁵ are each a saturated hydrocarbon group having 1 carbon atom. R ⁶ is a hydroxyalkyl group having 3 carbon atoms, and Y ⁻ is a methyl sulfonate ion)

（上式（１）中、Ｒ^１、Ｒ^２はそれぞれＨであり、Ｒ^３は炭素数が３のアルキレン基であり、Ｒ^４、Ｒ^５はそれぞれ炭素数が１の飽和炭化水素基であり、Ｒ^６は炭素数が３のヒドロキシアルキル基であり、Ｙ⁻はメチルスルホネートイオンである。） Antistatic agent 2: A copolymer having a structure represented by the following formula (1) comprising 70 mol% / methoxy polyethylene glycol (n = 9) methacrylate 20 mol% / N-methylol acrylamide 10 mol%.

(In the above formula (1), R ¹ and R ² are each H, R ³ is an alkylene group having 3 carbon atoms, and R ⁴ and R ⁵ are each a saturated hydrocarbon group having 1 carbon atom. R ⁶ is a hydroxyalkyl group having 3 carbon atoms, and Y ⁻ is a methyl sulfonate ion.)

（上式（２）中、Ｒ^７、Ｒ^８はそれぞれＨであり、Ｒ^９は炭素数が３のアルキレン基であり、Ｒ^１０、Ｒ^１１はそれぞれ炭素数が１の飽和炭化水素基であり、Ｒ^１２は炭素数が３のヒドロキシアルキル基であり、Ｚ⁻はメチルスルホネートイオンである。） Antistatic agent 3: A copolymer having a structure represented by the following formula (2) comprising 70 mol% / methoxy polyethylene glycol (n = 9) methacrylate 20 mol% / N-methylol acrylamide 10 mol%.

(In the above formula (2), R ⁷ and R ⁸ are each H, R ⁹ is an alkylene group having 3 carbon atoms, and R ¹⁰ and R ¹¹ are each a saturated hydrocarbon group having 1 carbon atom. R ¹² is a hydroxyalkyl group having 3 carbon atoms, and Z ⁻ is a methyl sulfonate ion.)

Antistatic agent 4: Polyoxyalkylene chain-free cationic polymer (trade name “Charol DC-303P” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
Antistatic agent 5: Anionic polymer containing no polyoxyalkylene chain Sodium polystyrene sulfonate (trade name “Polynas PS-50” manufactured by Tosoh Organic Chemical Co., Ltd.)

Silicone 1: Polydimethylsiloxane (trade name “KM-862T” manufactured by Shin-Etsu Chemical Co., Ltd.)
Silicone 2: amino group-modified silicone (trade name “X-51-1178” manufactured by Shin-Etsu Chemical Co., Ltd.)
Silicone 3: Epoxy group-modified silicone (trade name “Polon MF-18T” manufactured by Shin-Etsu Chemical Co., Ltd.)
Silicone 4: Phenyl group-modified silicone (trade name “X-52-8148” manufactured by Shin-Etsu Chemical Co., Ltd.)
Crosslinking agent: Oxazoline compound (trade name “Epocross WS-700” manufactured by Nippon Shokubai Co., Ltd.)
Surfactant: Polyoxyalkylene alkyl ether (trade name “Naroacty CL-85” manufactured by Sanyo Chemical Co., Ltd.)

  The antistatic releasable polyester film of the present invention has high coating uniformity, can be produced easily and stably, and has stable releasability and antistatic properties. It can be suitably used for various applications requiring releasability such as printing, adhesive, ceramic molding, and transfer foil.

Claims (5)

An antistatic releasable polyester film having an antistatic release layer containing an antistatic agent and a release agent on at least one surface of the polyester film, wherein the antistatic agent contains a polyoxyalkylene chain And
The cationic polymer is formed from a structural unit A formed from a monomer represented by the following formula (1) or the following formula (2), and a monomer represented by the following formula (3) or the following formula (4). Comprising the structural unit B

(In the above formula (1), R ¹ and R ² are each H or a saturated hydrocarbon group having 1 to ³ carbon atoms, R ³ is an alkylene group having 1 to 10 carbon atoms, and R ⁴ and R ⁵ are Each is a saturated hydrocarbon group having 1 to 3 carbon atoms, R ⁶ is H or a hydroxyalkyl group having 2 to 4 carbon atoms, and Y ⁻ is a halogen ion, nitrate ion, sulfate ion, alkyl sulfate ion, or sulfonate ion. Or an alkyl sulfonate ion)

(In the above formula (2), R ⁷ and R ⁸ are each H or a saturated hydrocarbon group having 1 to 3 carbon atoms, R ⁹ is an alkylene group having 1 to 10 carbon atoms, and R ¹⁰ and R ¹¹ are Each is a saturated hydrocarbon group having 1 to 3 carbon atoms, R ¹² is H or a hydroxyalkyl group having 2 to 4 carbon atoms, and Z ⁻ is a halogen ion, a nitrate ion, a sulfate ion, an alkyl sulfate ion, or a sulfonate ion. Or an alkyl sulfonate ion)

(In the above formula (3), R ¹³ and R ¹⁴ are each H or a saturated hydrocarbon group having 1 to 3 carbon atoms, and A ₁ is a total of 2 to 20 oxyethylene units and / or oxypropylene in the molecule. Each represents a residue obtained by removing one hydroxyl group from a polyoxyalkylene diol having a polyoxyalkylene group composed of units)

(In the above formula (4), R ¹⁵ and R ¹⁶ are each H or a saturated hydrocarbon group having 1 to 3 carbon atoms, and A ₂ is a total of 2 to 20 oxyethylene units and / or oxypropylene in the molecule. Each represents a residue obtained by removing one hydroxyl group from a polyoxyalkylene diol having a polyoxyalkylene group composed of units)
An antistatic releasable polyester film, wherein the release agent is a silicone compound, and the content thereof is 20% by weight or more based on the weight of the antistatic release layer. The antistatic releasable polyester film according to claim 1, wherein the peel strength of the pressure-sensitive adhesive tape by the following measurement method on the surface of the antistatic release layer is 300 g / 10 mm or less.
[Measurement method of peel strength]
An adhesive tape (manufactured by Nitto Denko Corporation, product name “No. 31B”) is bonded to the surface of the antistatic release layer, pressed with a 5 kg pressure roller, allowed to stand for 20 hours, and then measured with a tensile tester. The antistatic release polyester film according to claim 1 or 2, wherein the cationic polymer further comprises a structural unit C formed from a monomer represented by the following formula (5).

(In the above formula (5), R ¹⁷ and R ¹⁸ are each H or a saturated hydrocarbon group having 1 to 3 carbon atoms, and R ¹⁹ is H or a saturated hydrocarbon group having 1 to 6 carbon atoms, respectively)   The structural unit A comprises 60 mol% or more and 99.9 mol% or less and the structural unit B in a range of 0.1 mol% or more and 40 mol% or less based on all the structural units of the cationic polymer. The antistatic releaseable polyester film according to any one of the above.   The silicone compound according to any one of claims 1 to 4, wherein the silicone compound is at least one selected from the group consisting of polydimethylsiloxane, epoxy group-containing silicone, amino group-containing silicone, and silicone having a hydrocarbon group having 6 or more carbon atoms. The antistatic releaseable polyester film as described.