KR101591409B1 - Release film - Google Patents

Abstract

Provided in the present invention is a release film comprising a base film made of polyimide; a contact layer formed on at least one surface of the base film, and made of a thermosetting melamine resin; and a release layer formed on the contact layer, and made of silicone-acrylic resin. The release film according to the present invention has less dimensional change in a high temperature compression process by using a polyimide film hardly affected by thermal deformation even at high temperatures based on high thermal resistance thereof. Also, the release layer is made of the silicone-acrylic resin, and has excellent coating properties of resin and separation of the release film after processes. Furthermore, the release film comprises the contact layer between the release layer and the base material, thereby not having defects caused by movement of components forming the release layer, and preventing defects caused by transfer and treatment of the release film, and separation of the release layer in a hot-press process.

Description

Release Film {RELEASE FILM}

The present invention relates to a release film, and more particularly, to a release film comprising a base film and a release layer formed by using a melamine resin as a main component and having heat resistance and releasability in a high temperature compression process, To a release film having improved adhesion.

The release film is generally used as a protective film for protecting the adhesive component from foreign substances in the atmosphere or unwanted adherents by adhering to the adhesive film, and generally has a structure in which a release layer is provided on one side of the base film.

Another application of the release film is a high temperature compression process. In order to laminate an interlayer insulating material on a multilayer printed circuit board, a resin such as an epoxy is coated on a release film, A prepreg process in which a releasing film coated with a semi-cured resin is heated and pressed on an adherend or a mold to form a glass fiber composite, a prepreg process in which a releasing film is peeled off, Of the polymer resin is injected into the mold to cure and then peel off.

In general, the release film is formed of a polyester film as a base material and a polymer silicon as a release layer. However, such a silicone release film has a disadvantage in that the printability is deteriorated due to a specific low surface energy. Therefore, when the carrier film is applied to the carrier film as the object of the present invention, it is difficult to obtain a uniform coating film due to poor wettability or pinholes in the process of directly coating other resin on the release layer in a hot press process or the like.

A method of forming a release layer of a silicone-acrylic resin on one side of a polyester film as a method of implementing a release layer having improved printability has been proposed (Patent Document 1), but in such a structure, There is a problem in that the shape of the molded product becomes poor due to the deformation of the release film when applied to a high-temperature compression process requiring a temperature of 150 ° C or higher. In this case, since the inert functional groups of the polyimide film interfere with the curing of the silicone-based releasing agent, a typical addition reaction-type silicone resin can not form the releasing layer in the case of a polyimide film having higher heat resistance It is known that it can not be provided.

There has been provided a release film having improved heat resistance by forming a release layer by using a silicon-containing amino alkyd resin as a base material of a polyimide film (Patent Document 2). However, there are limitations that can not be applied to a resin having a high adhesion And the adhesion between the releasing layer and the substrate is poor, which is vulnerable to problems of transportation, handling, and separation of the releasing layer due to friction during the process.

Japanese Laid-Open Patent Publication No. 1999-170440 Japanese Laid-Open Patent Publication No. 2014-091763

It is an object of the present invention to provide a resin composition which not only has excellent heat resistance and releasability even in a high temperature compression process such as hot press molding and in-mold molding, but also improves adhesion between a base film and a release layer, And to provide a release film which can be applied to a pressing process.

A release film according to the present invention comprises: a base film made of a polyimide; An adhesion layer provided on at least one surface of the base film and formed of a thermosetting melamine resin; And a release layer formed on the adhesion layer and formed of a silicon-acrylic resin.

Wherein the melamine resin is selected from the group consisting of melamine monomer selected from the group consisting of monomethiol melamine, dimethiol melamine, trimethiol melamine, tetramethiol melamine, pentamethiol melamine, and hexamethiol melamine, and melamine monomer selected from formaldehyde Methylol melamine resin prepared by the condensation reaction of methylol melamine resin; An ether type melamine resin in which a condensation reaction of formaldehyde with a melamine monomer in which 1 to 6 substituents are substituted with an alkoxyalkyl group having 1 to 12 carbon atoms; An imino-type melamine resin derived from melamine wherein all of the substituents are hydrogen atoms; Alkylated melamine resins such as methylated melamine resins and butylated melamine resins; Or a mixture thereof.

The thickness of the adhesion layer is preferably 0.1 to 6 mu m.

The silicone-acrylic resin preferably includes the following structural formula (1)

[Chemical Formula 1]

구성 단위를 함유하는 실리콘 성분이고, 상기 실리콘의 중합도(n)는 1 내지 300이다.Wherein R ¹ is a hydrogen atom or a methyl group, R ² is

( N ) of the silicon is from 1 to 300;

The release film according to the present invention employs a polyimide film having a high heat resistance and a low thermal deformation even at a high temperature as a substrate, so that the dimensional change of the release film is small in a high-temperature compression process. In addition, the releasing layer is constituted of a silicone-acrylic resin, so that the coating property of the resin and the peeling property of the release film after the processing are excellent. Furthermore, by providing the adhesive layer between the releasing layer and the substrate, there is no defect caused by migration of the releasing layer constituent, and defects due to removal and release of the releasing layer during hot pressing can be prevented.

1 is a schematic cross-sectional view of a release film according to the present invention.

Hereinafter, a release film according to the present invention will be described with reference to the accompanying drawings.

1 is a schematic cross-sectional view of a release film according to the present invention. 1, a release film 10 according to the present invention comprises a base film 11 made of polyimide; An adhesion layer (12) provided on at least one surface of the base film (11) and formed of a thermosetting melamine resin; And a release layer (13) formed on the adhesion layer (12) and formed of a silicon-acrylic resin.

The base film (11)

The polyimide film that can be used as the base film may be any commercially available product used in the art, and a commercially available product may be used. Examples of commercially available polyimide films include Kepton-series products of `Toray-DuPont`, and IN-LV, IF-LN and LS series products of` SKK CORONOPIA`.

On the other hand, the thickness of the polyimide film is not particularly limited, but preferably 10 to 100 탆 is used. When the thickness of the polyimide film is less than 10 mu m, the heat resistance is insufficient, resulting in dimensional defects of the formed product. When the thickness of the polyimide film exceeds 100 mu m, the releasability of the release film is reduced.

The adhesive layer (12)

The adhesion layer is characterized by containing a melamine resin. The adhesion layer is formed by applying a diluted solution prepared by mixing a melamine resin and an organic solvent onto one surface of a polyimide film, followed by hot air drying. The melamine resin is prepared by the reaction of melamine and formaldehyde. In the present invention, the melamine resin is thermally cured at a low temperature to improve adhesion of the release layer described later to the base film described above.

Examples of the melamine resin in the present invention include one or two of the group consisting of monomethiol melamine, dimethiol melamine, trimethiol melamine, tetramethyl melamine, pentamethiol melamine, and hexamethiol melamine. Methylol melamine resin prepared by the condensation reaction of melamine monomer and formaldehyde selected above; An ether type melamine resin in which a condensation reaction of formaldehyde with a melamine monomer in which 1 to 6 substituents are substituted with an alkoxyalkyl group having 1 to 12 carbon atoms; An imino-type melamine resin derived from melamine wherein all of the substituents are hydrogen atoms; Alkylated melamine resins such as methylated melamine resins and butylated melamine resins; .

The above-mentioned melamine resins are commercially available, and include, for example, CYMEL series products manufactured by Cytech Industries, Sumitec resin series (M-3, MK, M-6, MC, ), Methylated melamine resin (MW-22, MX-706, etc.) manufactured by Sanwa Chemical Co., Ltd. are commercially available.

On the other hand, there is no particular restriction on the organic solvent, and in consideration of the compatibility with the melamine resin and the coating property, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), cyclohexanone (CCH) And the like can be used.

When the solid content is less than 0.1% by weight, the melamine resin does not completely cover the surface of the base material and the adhesion improving effect is insufficient. When the solid content is less than 0.1% by weight, the solubility of the solid content Is more than 30% by weight, the curing performance of the adhesive layer is deteriorated, and it is difficult to obtain a uniform adhesive layer due to the high viscosity of the solution, and the economical efficiency is deteriorated due to excessive use of the resin.

The adhesion layer may further include acid catalysts such as dynonylnaphthalenesulfonic acid, dynonylnaphthalene disulfonic acid, alkylbenzenesulfonic acid, para-toluenesulfonic acid and phosphoric acid to improve the curing speed of the melamine resin.

The adhesion layer is preferably formed to a thickness of 0.1 to 6 mu m. If the thickness of the adhesive layer is less than 0.1 占 퐉, the base film can not be completely covered and the effect of improving the adhesion is insufficient. If the thickness exceeds 6 占 퐉, the adhesive layer is not completely cured and adherence deteriorates. In order to completely cure the adhesive layer When the drying time is improved, the economical efficiency is lowered, and it is accompanied by a secondary problem such as heat wrinkles.

The release layer (13)

The release layer is characterized by containing a silicone-acrylic resin, which is obtained by applying a composition obtained by mixing a silicone-acrylic resin and an organic solvent onto the adhesion layer, followed by hot air drying.

The silicone-acrylic resin has a structure in which a silicone polymer is grafted to an acrylic skeleton, and more specifically, the silicone-acrylic resin includes a structural unit represented by the following formula (1).

[Chemical Formula 1]

구성 단위를 함유하는 실리콘 성분이고, 상기 실리콘의 중합도(n)는 1 내지 300이다.Wherein R ¹ is a hydrogen atom or a methyl group, R ² is

( N ) of the silicon is from 1 to 300;

The degree of polymerization (n) of the silicone polymer R ² is preferably 1 to 300, and when it is more than 300, curing failure may be caused due to steric hindrance when used with a curing agent.

The structural unit of Formula 1 is copolymerized with a structural unit derived from a conventional alkyl (meth) acrylate to form a silicone-acrylic resin. The alkyl (meth) acrylate is a (meth) acrylate having as a substituent a linear, branched or cyclic alkyl group having from 1 to 18 carbon atoms, such as methyl (meth) acrylate, ethyl (meth) (Meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (Meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate and benzyl (meth) acrylate. These may be used alone or in combination of two or more.

The preferred content of the silicone acrylate constituent unit represented by the general formula (1) contained in the silicone-acrylic resin is 0.01 to 50 mol%. When the content of the silicone acrylate is less than 0.01 mol%, it is not suitable for realizing the desired releasing force. When the amount of the silicone acrylate exceeds 50 mol%, the present invention It is not preferable for the purpose of.

The silicone-acrylic resin may contain a functional group unit in the polymer chain. The functional group constituting unit is not particularly limited, but preferably any functional group selected from the group consisting of a hydroxyl group, an amino group and a carboxyl group is included in the crosslinking reaction site And react with the curing agent to form a crosslinking point.

The releasing layer of the present invention may be formed from a releasing agent solution containing a curing agent in the silicone-acrylic resin. Preferably, when the total amount of the silicone-acrylic resin and the curing agent is 100% by weight, the curing agent (B ) Is contained in an amount of 1 to 90% by weight. The curing agent may be any one selected from the group consisting of a polyfunctional amino compound, a polyfunctional isocyanate compound, a polyfunctional epoxy compound, and a polyfunctional metal compound.

On the other hand, when the silicone-acrylic resin and the organic solvent are mixed, the solid content of the solution is preferably 0.1 wt% or more. When the solid content is less than 0.1 wt%, the releasability of the silicone-acrylic resin is poor. Commercially available silicone-acrylic resins generally have a solids content of less than 50 wt.%, Which is known to be due to the high viscosity of the silicone-acrylic resin when the solids content exceeds 50 wt.%.

On the other hand, the release layer of the above composition is formed by coating by an in-line or off-line coating method. The release layer preferably has a thickness within a range of 0.05 to 3 mu m after drying. If the thickness after drying of the releasing layer is less than 0.05 mu m, peeling force may increase and unevenness may occur. On the other hand, if the thickness exceeds 3 mu m, there may be problems such as uncured, blocking and solvent- have.

The coating method applied to the formation of the adhesive layer and the release layer is not particularly limited, and any one of gravure, comma, Meyer bar, lip, die, and spray may be applied.

Hereinafter, the present invention will be described in more detail with reference to Examples. The present invention is intended to more specifically illustrate the present invention, and the scope of the present invention is not limited by these examples.

<Examples>

1. Equipment

(Manufactured by Toray-DuPont, product name: KEPTON H) having a thickness of 50 mu m was used as a substrate.

2. Melamine resin and composition

Melamine resin (Cytec, product name: CYMEL-325) having a solid content of 100% was used, and MEK was diluted with a proper ratio by using a solvent, Thereby preparing a melamine resin composition having a solid content. (In the case of Comparative Example 4, no adhesion layer was formed).

3. Formation of adhesion layer

The melamine resin composition was applied on the substrate to a thickness of 20 mu m using a Meyer bar, and then dried by a hot air dryer in a hot air dryer for 5 minutes to form an adhesion layer. In this case, the thickness of the adhesive layer after drying can be calculated from the product of the coating thickness before drying and the total solid content of the melamine resin composition, and the examples and comparative examples were formed in the range of 0.3 to 7 mu m. (In the case of Comparative Example 4, no adhesion layer was formed).

4. Silicone-acrylic resin and composition

(TOGOSEI, product name: CYMAC 270) having a solid content of 30% was used and diluted in an appropriate ratio using MEK as a solvent to obtain a silicone-acrylic resin To prepare a silicone-acrylic resin composition having the corresponding solid content.

5. Formation of release layer

A silicone-acrylic resin composition was applied on the adhesive layer to a thickness of 20 탆 using a Meyer bar and then dried in a hot-air dryer for 5 minutes to form a release layer to produce a release film having a release layer having a thickness of 0.012 to 6.0 탆 . A release film as a final product was prepared. (In the case of Comparative Example 4, no adhesion layer was formed and a release layer was formed directly for the substrate layer).

Adhesive layer composition Structure of heterogeneous layer Melamine resin
Content (g) MEK
Content (g) Total solids
(%) Silicone-Acrylic
Resin content (g) MEK
Content (g) Total solids
(%) Example 1 0.15 99.85 1.50 40.0 60.0 12.0 Example 2 27.0 73.0 27.0 40.0 60.0 12.0 Example 3 15.0 85.0 15.0 4.0 96.0 0.12 Example 4 15.0 85.0 15.0 100.0 0.0 30.0 Comparative Example 1 0.05 99.95 0.05 40.0 60.0 12.0 Comparative Example 2 35.0 65.0 35.0 40.0 60.0 12.0 Comparative Example 3 15.0 85.0 15.0 2.0 98.0 0.06 Comparative Example 4 none none none 40.0 60.0 12.0

<Experimental Example>

In order to evaluate the performance of the release films of Examples 1 to 4 and Comparative Examples 1 to 4, the following experiment was conducted.

1. Appearance

After the release films of Examples 1 to 4 and Comparative Examples 1 to 4 were produced and visually observed under a fluorescent lamp, the appearance of the adhesive layer and the release layer were evaluated. If the adhesion layer and the release layer of the release film were uniformly applied and the longitudinal stripes due to the Meyer bar were not observed, `good` longitudinal stripes appeared, or when the thick or low thickness of the coating was visually observed,` poor` Respectively.

2. Epoxy peelability

A curable epoxy resin solution was coated on the release layers of the release films of Examples 1 to 4 and Comparative Examples 1 to 4, followed by hot air drying at 130 캜 for 3 minutes to mold an epoxy resin sheet. Thereafter, a polyimide film not subjected to releasing treatment was laminated on the epoxy resin surface, and cured at 170 DEG C for 30 minutes while being pressed with an iron plate having a load of 10 kg. Thereafter, the epoxy resin was peeled off from the release film, and the ratio of the peeled portion (the portion where the epoxy resin did not remain in the release film) to the whole epoxy resin molding area was expressed in percent (%).

As the epoxy resin solution used in the experiment, 200 parts by weight of an epoxy resin (KODO CHEMICAL, product name: KSR-177), 100 parts by weight of a phenoxy resin (KODO CHEMICAL, trade name: YP-55) and 400 parts by weight of MEK were mixed, , And 4 parts by weight of 1-cyanoethyl-2-phenylimidazole (Shikoku Kasei, product name: 2PZCN) as a curing agent were added and further stirred for 1 hour was used.

3. Adhesiveness

The surfaces of the release layers of the release films of Examples 1 to 4 and Comparative Examples 1 to 4 were repeatedly rubbed with a test nonwoven fabric (manufacturer: DUPONT, product name: SONTARA) 30 times. Thereafter, the same experiment as in Experimental Example 2 was carried out using an epoxy resin, and the proportion of the portion where the epoxy resin was peeled was expressed by the same method.

Table 2 summarizes the experimental results of the above experimental examples.

Composition of release film Experiment result Of the melamine resin composition
Solid content (%) Silicone-Acrylic
The resin composition
Solid content (%) Exterior Epoxy
Peelability (%) Adhesion (%) Example 1 1.50 12.0 Good 100 99 Example 2 27.0 12.0 Good 100 100 Example 3 15.0 0.12 Good 95 94 Example 4 15.0 30.0 Good 100 100 Comparative Example 1 0.05 12.0 Good 100 23 Comparative Example 2 35.0 12.0 Bad 100 100 Comparative Example 3 15.0 0.06 Good 53 51 Comparative Example 4 none 12.0 Good 100 0

As shown in Table 2, in Examples 1 to 4, in which a pressure-sensitive adhesive layer was formed from a melamine resin composition having a preferable solid content range provided by the present invention, and a release layer was formed from a silicone acrylic resin composition having a preferable solid content range , The appearance of the release film is good and the epoxy resin remaining in the release film is excellent within 5% at the time of forming the epoxy resin and peeling after the high-temperature compression bonding process, and the releasability of the release film is maintained even after 30- The peelability of the resin was good.

On the other hand, in the case of Comparative Examples 1 to 4 in which the solid content of the melamine resin composition and the silicone-acrylic resin composition deviates from the preferable range, any one of the appearance, the epoxy peeling property and the adhesion property of the release film was poor.

In the case of Comparative Example 4 in which no adhesion layer was formed, the epoxy peelability was good, but after the repeated test of 30 times, the release layer completely disappeared and no peeling of the epoxy resin was observed.

From the above experimental results, it was confirmed that when the polyimide film is employed as a substrate, the adhesion layer provided in the present invention has an excellent effect in preventing the release layer from falling off from repeated rubbing.

The release film produced according to the present invention has excellent coating properties in various resins and is excellent in peelability between a resin and a release layer even when a heat treatment at a high temperature and a long time is required. Therefore, various adhesive, semi-curable adhesive, (Such as glass fiber or carbon fiber) prepregs for printed circuit boards, and the like.

10. Release film 11. Base film
12. Adhesive layer 13 .. Release layer

Claims (4)

A base film made of polyimide;
An adhesive layer provided on at least one surface of the base film and formed by curing at least one thermosetting melamine resin composed of a methylol melamine resin, an ether melamine resin, an imino melamine resin and an alkylated melamine resin; And
And a releasing layer formed on the adhesive layer and formed of a silicone-acrylic resin. delete The release film according to claim 1, wherein the thickness of the adhesive layer is 0.1 to 6 占 퐉. The release film according to claim 1, wherein the silicone-acrylic resin comprises a structural unit represented by the following formula (1):
[Chemical Formula 1]

Wherein R ¹ is a hydrogen atom or a methyl group, R ² is

( N ) of the silicon is from 1 to 300;

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