JPH10217409A - Antistatic mold release film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold release layer in which troubles due to static electricity can be avoided by applying a coating liquid containing a block copolymer of an azo compound having polysiloxane, a polyethylene glycol segment and acrylic monomer to one side of a polyester film to provide a mold release layer. SOLUTION: A coating liquid containing block copolymer represented by formula I of an azo compound having polysiloxane segment and acrylic monomer and a copolymer represented by formula II and having a polyethylene glycol segment is applied to one side of a polyester film to provide a mold release layer, wherein R1 is a methyl group or phenyl group; R2 is a 1-5 C alkylene group; x and y are each a number satisfying the relationship of 0.10<=x<=0.50, 0.50<=y<=0.90 and x+y=1; n shows a number of 10-1000. And R3 is a 1-5 C arlylene group; u and v are each a number satisfying the relationship of 0.10<=u<=0.50, 0.50<=v<=0.90 and u+v=1; m shows a number of 10-1000.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a release film, and more particularly, to a release film having stable antistatic properties and excellent release properties.

[0002]

2. Description of the Related Art Conventionally, a composition comprising a curable silicone as a main component has been cured on the surface of a base material such as various papers, synthetic films, fibers and the like to form a coating, thereby releasing the adhesive material from the adhesive. It is well known to impart properties.

[0003] In recent years, with the wide application of pressure-sensitive adhesives and adhesives, the use of silicone-coated paper and films for protecting the pressure-sensitive adhesive surface has been remarkably growing in various fields.
Such curable silicone compositions include those which are cured by a condensation reaction (JP-A-47-34447).
Or those cured by an addition reaction (Japanese Patent Publication No. 52-409)
No. 18).

[0004] However, the silicone coating thus formed has the drawback that it does not leak charge and is easily charged due to the main chain bond and steric structure of the silicone. That is, the main chain —Si—O—Si
The-bond is basically a δ bond, though it is ionic, as compared with the -CC- bond, and cannot delocalize the electric charge unlike a conjugated double bond or the like. In addition, the two methyl groups bonded to Si are directed to the outside of the main chain to form a hydrophobic field, making it impossible for electric charges to leak through moisture and impurity ions in the air.

A film coated with such a silicone film naturally has a high chargeability, and causes various obstacles. Therefore, antistatic properties of the release film have been required for a long time.

[0006] Many adhesive processed products using a release film have a heavy release phenomenon. This heavy release phenomenon is roughly divided into two, and the peel strength is high in a wide portion of the release film. (Heavily peeled)
This is the case where the peel strength becomes extremely high at points or lines of the release film or locally. The former is generally considered to be heavy peeling due to exposure to the atmosphere, and the latter is thought to be mainly due to static electricity. The latter cause is derived from the following experiment.

(A) When the release film is stored under the condition that the dust hardly adheres, the peeling does not become heavy. (A) When the release film is stored in a clean room, it is less likely to cause heavy peeling than in a normal room. (C) The release film that has been heavily peeled is lightly peeled off when washed with water, but is not lightly peeled off even when washed with an organic solvent. (D) Even if various kinds of powders are dusted, they do not always cause heavy peeling. (E) Even if the release film is stored under light-shielding conditions such as a dark room, heavy release occurs.

From the results of the above (c), it is inferred that electric energy is involved in the local heavy exfoliation. From the results of the above (d), uncharged particles or particles having a large particle size are heavy. It turns out that exfoliation does not occur. The above (e)
From the results, it can be seen that ultraviolet rays and the like are not a factor of heavy separation.

At present, the most effective countermeasure against static electricity damage is static elimination, which is implemented by installing static elimination equipment in various places in the release film manufacturing process and the adhesive processing process. Not obtained. A typical field is the LCD industry, which has been rapidly developing in recent years. If dust, dust, dust, or the like in the air adheres in the process of attaching the polarizing plate to the liquid crystal glass, the product will be defective, and the yield will be greatly reduced.

Therefore, as a method for preventing the release film from charging such a problem, a method of providing a curable silicone layer on the antistatic layer (Japanese Patent Publication No. 3-106645) or an internal addition of an antistatic agent. An antistatic silicone release film has been proposed, such as a method of providing an ultraviolet-curable silicone coating on a plastic film (Japanese Patent Publication No. 4-59207).

However, when an antistatic agent containing nitrogen, sulfur, and phosphorus is mixed with an addition-curable silicone, they become
Since it coordinates with t and acts as a so-called catalyst poison, there is a problem that curing is impaired, and the development of a single-layer antistatic silicone on a general-purpose plastic film is required.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to overcome the drawbacks and problems of the prior art and to provide a release layer free from electrostatic damage, various kinds of adhesive coatings, resin sheets, ceramic sheets and the like. An object of the present invention is to provide a release film having a release layer which can be peeled off with an appropriate force (has good releasability) and has excellent stability over time.

[0013]

The present invention provides a block copolymer of an azo compound having a polysiloxane segment and an acrylic monomer, and an azo compound having a polyethylene glycol segment and an acrylic monomer on at least one surface of a polyester film. And a release film provided with a release layer obtained by applying a coating liquid containing the block copolymer. Hereinafter, the present invention will be described in detail.

[Polyester Film] In the present invention, a polyester film is used as a base film. For applications requiring transparency, a polyester film having good transparency is preferably used. Particularly preferred. For applications requiring light-shielding properties, a biaxially oriented polyester film containing an inorganic pigment is preferred, and a white biaxially oriented polyester film containing a pigment such as TiO ₂ or SiO ₂ is particularly preferred.

The polyester constituting such a polyester film is preferably a crystalline linear saturated polyester comprising an aromatic dibasic acid component and a diol component. Examples of the polyester include polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate and polyethylene terephthalate. 2,6-naphthalate and the like can be mentioned.

The above polyester has an average particle size of 0.1 as a lubricant in order to improve the slipperiness of the film.
Organic fine particles or inorganic fine particles of about 01 to 20 μm can be contained, for example, in a mixing ratio of 0.005 to 20% by weight. Specific examples of such fine particles include inorganic fine particles such as calcium carbonate, kaolin, silicon oxide, and barium sulfate, and organic fine 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 polymerization reaction of the polyester, fine irregularities can be formed on the film surface, and the film can have good sliding properties.

Further, other improving agents can be blended with the polyester. For example, a compound having a sulfonate group such as sodium dodecylbenzene sulfonate can be contained as an antistatic agent.

The polyester film used 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 at a temperature of Tm to (Tm + 70) ° C. (where Tm is the melting point of the polyester) with an extruder, and forming a die (eg, a T-die, an I-die, etc.). ), And extruded on a rotary cooling drum, and quenched at 40 to 90 ° C. to produce an unstretched film.
0) to (Tg + 70) ° C. (Tg: glass transition temperature of polyester), stretching in the longitudinal direction at a magnification of 2.5 to 8.0 times, and stretching in the transverse direction at a magnification of 2.5 to 8.0 times. If necessary, it can be manufactured by heat setting at a temperature of 180 to 250 ° C. for 1 to 60 seconds. Film thickness is 5-25
A range of 0 μm is preferred.

[Release Layer] In the present invention, on at least one side of the polyester film, a block copolymer of an azo compound having a polysiloxane segment and an acrylic monomer, and an azo compound having a polyethylene glycol segment and an acrylic monomer Is provided with a release layer obtained by applying a coating solution containing the block copolymer described above.

The acrylic monomers include methyl acrylate, ethyl acrylate, isopropyl acrylate,
N-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-hexyl methacrylate, lauryl methacrylate, acrylic acid, methacrylic acid, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, acrylamide, N-methylolacrylamide, diacetoneacrylamide, glycidyl methacrylate, styrene, vinyltoluene, vinyl acetate, acrylonitrile and the like are preferable. Can be illustrated. Of these, methyl methacrylate is more preferred. Also,
Other compounds having a carbon-carbon double bond, such as maleic acid, itaconic acid, styrene, vinyltoluene, vinyl acetate, etc., can be added to the acrylic monomer. The acrylic monomer to be block-copolymerized with an azo compound having a polysiloxane segment and the acrylic monomer to be block-copolymerized with an azo compound having a polyethylene glycol segment may be the same or different. .

A block copolymer (A) formed from an azo compound having a polysiloxane segment shown in the following reaction formula and methyl methacrylate is particularly preferred.

[0022]

Embedded image

[In the above reaction formula, R ₁ is a methyl group or a phenyl group, R ₂ is an alkylene group having 1 to 5 carbon atoms, and x and y are 0.10 ≦ x ≦ 0.50 and 0.50 ≦ y ≦
A number satisfying the relationship of 0.90 and x + y = 1, n is 10
Shows a number of ~ 1000. ]

When x in the above reaction formula is less than 0.10, the releasability is lowered and the pressure-sensitive adhesive layer laminated on the release layer may be difficult to peel off, while when x exceeds 0.50. In some cases, the wettability of the release layer is reduced to cause cissing of the aqueous coating liquid.

Next, as a block copolymer of an azo compound having a polyethylene glycol segment and an acrylic monomer, a block copolymer of an azo compound having a polyethylene glycol segment and an acrylic monomer shown in the following reaction formula ( B) is particularly preferred.

[0026]

Embedded image

[In the above reaction formula, R ₃ is an alkylene group having 1 to 5 carbon atoms, and u and v are each 0.10 ≦ u ≦ 0.5.
0, 0.50 ≦ v ≦ 0.90 and a number satisfying the relationship of u + v = 1, and m indicates a number of 10 to 1,000. When u in the above reaction formula is less than 0.10, the antistatic property is insufficient, and a charging failure occurs. On the other hand, when u exceeds 0.50, the release layer becomes soft.

In order to further improve the antistatic performance, it is preferable to add a compound capable of generating Li ions to the above-mentioned block copolymer of the azo compound having a polyethylene glycol segment and an acrylic monomer. Preferred examples of the compound capable of generating Li ions include lithium oxalate and tert-butyllithium. Such Li ions have a small ionic radius and can easily move in a helical molecule formed by polyethylene glycol. The amount of the compound capable of generating Li ions is 5 to 5% based on the total solid content of the coating solution.
30% by weight is preferred.

A block copolymer (release-imparting element) formed from an azo compound having a polysiloxane segment forming a release layer and methyl methacrylate; an azo compound having a polyethylene glycol segment and an acrylic monomer; The combination ratio (weight ratio) of the block copolymer (antistatic property-imparting element) is 80/20 to 5
The range of 0/50 (the releasing element / the antistatic element) is preferable. If the combination ratio is out of this range, the releasability or antistatic property is insufficient.

The release layer in the present invention may contain various known additives within a range not to impair the object of the present invention. As this additive, for example, ultraviolet absorbers, pigments,
Examples include an antifoaming agent, a pot life extending agent, a crosslinking agent, and the like.

[Method of Coating Release Layer] The release layer according to the present invention comprises, on at least one surface of a polyester film, a block copolymer of an azo compound having a polysiloxane segment and an acrylic monomer, and a polyethylene glycol segment. A coating liquid containing a block copolymer of an azo compound and an acrylic monomer is applied and dried by heating to form a coating film. The heating conditions are preferably, for example, 80 to 160 ° C. for 20 to 120 seconds, particularly 100 to 150 ° C. for 30 to 60 seconds, since the drying of the coating film becomes sufficient. In addition,
As a coating method of the coating liquid, any known method can be applied,
For example, a roll coater method, a blade coater method and the like can be preferably mentioned, but the method is not limited to these methods.

[0032]

The present invention will be further described below with reference to examples. The properties of the release film were measured by the following methods,
evaluated.

1. Peel strength A polyester adhesive tape (Nitto 31B) is stuck to the release layer surface of the release film, pressed with a 5 kg pressure roller and left for 20 hours, and the peel force between the release layer and the adhesive tape is measured with a tensile tester. did. The preferable range of the peel strength is 5 to 100 g / inch. If the peel strength is 5 g / inch 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 undesirably peeled off. On the other hand, if the peel strength is 100 g / inch or more, peeling may be difficult when a resin sheet or the like is peeled and separated from the laminated sheet, which is not preferable.

2. Residual adhesion rate JIS polyester adhesive tape (Nitto 31B)
Cold rolled stainless steel sheet (SUS3
04) was measured for the peeling force after application, and the result was taken as the basic adhesive force (f ₀ ). Further, the polyester pressure-sensitive adhesive tape was pressure-bonded to the release layer surface of the release film with a pressure roller of 5 kg and maintained for 30 seconds, and then the pressure-sensitive adhesive tape was peeled off. Next, the peeling force after attaching the peeled adhesive tape to the above stainless steel plate was measured, and the measured value was defined as a residual adhesive force (f). From the obtained basic adhesive strength (f ₀ ) and residual adhesive strength (f), a residual adhesive rate was determined using the following equation.

[0035]

## EQU1 ## Residual adhesion rate (%) = (f / f ₀ ) × 100

The preferred range of the residual adhesion ratio is 85%.
That is all. If the residual adhesion ratio is less than 85%, for example, when the release film is wound up in a roll and stored, the components constituting the release layer are transferred to the surface of the adjacent film (so-called backside transfer), and the release is performed. This is not preferred because the properties of the layer may be poor or the properties such as the adhesiveness of the adjacent film surface may be poor.

3. Surface Specific Resistance The surface specific resistance was measured using a super insulation resistance meter (RM-214, manufactured by Yokogawa Electric Corporation) based on ASTM D257.

Example 1 In a block copolymer (A) of an azo compound having a polysiloxane segment as a mold release imparting element and an acrylic monomer, R ₁ is a methyl group, R ₂ is an ethylene group, and x is 0.20, y is 0.8
In a block copolymer (B) of an azo compound having a polyethylene glycol segment as an antistatic property-imparting element and an acrylic monomer, 50 parts by weight of a block copolymer in which 0 and n are 250, and R ₃ is an ethylene group , U of 0.40, v of 0.60 and m of 300 were mixed with 50 parts by weight of a block copolymer. This mixture was dissolved in methyl ethyl ketone in such an amount that the solid concentration became 3% by weight. Next, lithium oxalate was dissolved in an amount of 10% by weight based on the total solid content of the solution to prepare a coating solution. This coating solution is applied on one surface of a biaxially stretched polyethylene terephthalate film having a thickness of 38 μm at a coating amount of 6 g / inch, dried at a temperature of 120 ° C. for 1 minute, and released with a thickness of 0.2 μm. Layers were provided. Table 1 shows the characteristics of the release film.

Example 2 An acrylic monomer was used as a mold release imparting element, 2-hydroxyethyl methacrylate,
50 parts by weight of a block copolymer (A) of an azo compound and an acrylic monomer having the same polysiloxane segment as in Example 1, except that x is 0.30, y is 0.70, and n is 300, Example 1 except that u was 0.5, v was 0.5, and m was 400 as the antistatic property-imparting element.
Was mixed with 50 parts by weight of a block copolymer (B) of an azo compound having the same polyethylene glycol segment and an acrylic monomer. This mixture was dissolved in methyl ethyl ketone in such an amount that the solid concentration became 3% by weight. Then, tert-butyllithium was dissolved in an amount of 10% by weight based on the total solid content of the solution to prepare a coating solution. Next, a release layer was provided on one surface of a biaxially stretched polyethylene terephthalate film having a thickness of 38 μm in the same manner as in Example 1. Table 1 shows the characteristics of the release film.

Comparative Example 1 A release film was obtained in the same manner as in Example 1 except that no antistatic element was added to the coating solution. Table 1 shows the characteristics of the release film.

[Comparative Example 2] A film having a coating layer was obtained in the same manner as in Example 1 except that no releasing agent was added to the coating liquid. Table 1 shows the properties of this film.

[0042]

[Table 1]

[0043]

According to the present invention, a release film having stable antistatic properties and excellent release properties can be obtained.

Claims (4)

[Claims] At least one surface of a polyester film contains a block copolymer of an azo compound having a polysiloxane segment and an acrylic monomer, and a block copolymer of an azo compound having a polyethylene glycol segment and an acrylic monomer. A release film provided with a release layer obtained by applying a coating solution to be applied. 2. A block copolymer of an azo compound having a polysiloxane segment and an acrylic monomer,
The antistatic release film according to claim 1, which is a compound represented by the following formula (A). Embedded image [In the formula (A), R ₁ is a methyl group or a phenyl group, R ₂ is an alkylene group having 1 to 5 carbon atoms, and x and y are each 0.1
0 ≦ x ≦ 0.50, 0.50 ≦ y ≦ 0.90 and x + y
= 1, and n represents a number of 10 to 1,000. ] 3. The antistatic release film according to claim 1, wherein the block copolymer of the azo compound having a polyethylene glycol segment and an acrylic monomer is a compound represented by the following formula (B). Embedded image [In the formula (B), R ₃ is an alkylene group having 1 to 5 carbon atoms,
u and v are respectively 0.10 ≦ u ≦ 0.50 and 0.50
A number that satisfies the relations ≦ v ≦ 0.90 and u + v = 1, m
Indicates a number of 10 to 1,000. ] 4. The antistatic release film according to claim 1, wherein a compound capable of generating Li ions is added to the coating solution in an amount of 5 to 30% by weight based on the total solid content in the coating solution.