KR101267828B1 - Adhesive Composition for Carrier Film and Carrier Film for Flexible Printed Circuit Board Thereby - Google Patents

Abstract

In the present invention, containing an acrylic resin having an hydroxy functional group and an isocyanate curing agent, 6 to 15 parts by weight of a mixture of toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) based curing agent based on 100 parts by weight of the acrylic resin, It provides an adhesive composition for a flexible circuit board protective film and a flexible circuit board protective film using the same, characterized in that it comprises 0.1 to 10 parts by weight of a plasticizer having an ester value of 100 or more.
Flexible circuit board protective film according to the present invention can effectively control the adhesion and high-speed peeling properties after the initial and high temperature compression to prevent the surface contamination and deformation of the flexible circuit board as the adherend. In addition, it minimizes surface contamination caused by etching liquid penetration and high temperature compression process during the circuit printing process of the flexible circuit board, thereby preventing adhesive transfer to the flexible product after peeling and damage to the product. Workability can be improved.

Description

Adhesive composition for protective film and flexible circuit board protective film using same {Adhesive Composition for Carrier Film and Carrier Film for Flexible Printed Circuit Board Thereby}

The present invention relates to a pressure-sensitive adhesive composition for a protective film and a flexible circuit board protective film using the same, and more particularly, an acrylic resin having a hydroxy functional group, a toluene diisocyanate (TDI), and a hexamethylene diisocyanate (HDI) -based curing agent mixture. It can effectively control the peel force change after the initial and high temperature compression, and contains a plasticizer having an ester value of 100 or more, which is advantageous for high-speed peeling, surface contamination by etching liquid infiltration during the circuit printing process of the flexible circuit board and It relates to a resin composition for a protective film that can prevent the transfer of pressure-sensitive adhesive to the flexible circuit board and product damage after peeling by minimizing the increase in peel force in the high compression process, and a flexible circuit board protective film using the same.

The protective film is a film used for the purpose of protecting the surface of a specific product. Therefore, the adhesive film should be applied on the inner surface or both sides. Process protective film (Carrier film) It is also called a protective film for the process as a kind of protective film also adheres to the adherend and passes all the processing steps of the adherend. This serves to prevent surface scratches and foreign substances that occur during the processing of the product and to prevent damage to the product itself.

The protective film mentioned in the present specification is used in the manufacturing process of the flexible circuit board in detail, and the scratch and etching solution and the plating solution of the surface film of the flexible circuit board in the process of printing, exposure, etching, plating, peeling, high temperature compression, etc. of the product. It protects against contamination by In particular, as the recent trend requires microcircuits, the flexible circuit board is changing from a three-layer structure in which copper foil is bonded to the film with an adhesive, and a two-layer structure in which the copper foil is directly raised on the film by a method such as deposition and plating without an adhesive. As a result, there is a problem that wrinkles may easily occur during process flow or other handling due to a thin thickness. For this reason, the defective rate of the product increases, and in order to compensate for this, the protective film is attached to the film side of the flexible product. The attached film can facilitate the handling of the product by simultaneously serving as a surface protection and a reinforcing material.

The main physical properties of the protective film for the process are to minimize the proper adhesion after the initial lamination and the change in the adhesion after the high temperature compression. More specifically, to minimize the increase of the adhesive force in the high temperature compression process of the flexible circuit board and to have the proper adhesion after the initial lamination. By preventing the lifting of the protective film during the etching process to prevent the penetration of the etchant and lifting of the punching surface during punching. In addition, since the peeling of the protective film is made in the form of a high speed in the state of the art should be advantageous to high-speed peeling.

In the case of the initial adhesive force is a factor affected by the lamination process, in the industry, the lamination at a high temperature of about 70 ~ 100 ℃, this temperature is also one of the important properties because the difference occurs depending on the manufacturer and process.

In patent document 1, an acrylic adhesive and an aliphatic polyisocyanate are used as a hardening | curing agent, and a tin type compound is used as a crosslinking promoter. However, it has not been able to effectively control changes in adhesion after high-temperature compression. Especially, the range of increase of the adhesive force after high-temperature compression is set to be within 4 times of the initial adhesive force. It is very difficult to remove the protective film when the adhesive force after high-temperature compression is about four times as high as the initial adhesive force under the assumption that the initial adhesive force is proper in the manufacturing process of the actual flexible circuit board. Inevitably, the flexible product is curled or torn The phenomenon of losing is inevitable. On the contrary, if the adhesive force after high-temperature compression does not cause damage to the product, the initial adhesive force is too low to cause peeling in the process flow even if initial adhesion is difficult or impossible. In addition, although tin is used as a curing accelerator, it does not specify the curing rate, that is, the gel fraction. The protective film is required to have the property that the residue of the adhesive when peeling is required for this purpose, the higher the gel fraction is good, but there is no mention of these parts in the literature it is difficult to know whether the residue.

And in patent document 2, the hardened | cured material of acrylic resin which has a hydroxyl group, and an isocyanate hardening | curing agent is used for the adhesion layer of a protective film. In the examples of this document, the increase in the adhesive force after high temperature compression is increased up to 5.3 times the initial adhesive force. This growth rate is also not suitable for practical use. Also, the gel fraction is not mentioned as in the previous literature.

In Patent Document 3, an acrylic pressure-sensitive adhesive having a carboxyl functional group and an epoxy-based curing agent are used, and the adhesive force is controlled. However, the level of adhesion is also higher than a certain level, so it is not likely to be practical. In addition, all of the above documents do not make any reference to the etching process of the flexible circuit board process. Etching process is a process that can be peeled off of the protective film, although the evaluation should be made about this, it is difficult to say that the proper evaluation was made because it is not mentioned.

In addition, the above documents are commonly referred to as high-speed peeling. In general, the adhesive force tends to be proportional to the peeling rate. As a result, the adhesive force increases as the peeling rate increases. Therefore, it is necessary to minimize the increase in adhesive force due to the increase in peeling speed, but there is no mention of such a part.

As described above, in order to solve product defects after peeling and etching, it is necessary to appropriately control the adhesive strength after initial and high temperature compression. If possible, there should be no change in adhesion due to high temperature compression. However, since the viscoelastic material is a viscoelastic material having fluidity at room temperature, it is difficult to control the change of adhesive force because the fluidity is doubled at a high temperature.

In general, when the adhesive force after high-temperature compression is lowered to prevent defects such as wrinkling of the product at the time of peeling or a phenomenon of drying in a circular shape, the initial adhesive force is significantly lowered, resulting in poor adhesion with the flexible circuit board. This problem also causes defects such as immersion of liquid due to peeling and partial lifting of the protective film in the etching process, which also causes a defect. On the contrary, if the initial adhesive force is raised to an appropriate level, the adhesive force after high temperature compression is too high, and the peeling of the protective film becomes difficult, causing wrinkles of the product.

In addition, a copper clad laminate (CCL) used in a flexible circuit board is required to have a protective film having various adhesive strength in accordance with its thickness and surface roughness. In particular, the PI film to which the protective film is attached varies depending on the manufacturer. Therefore, even if the protective film is of the same adhesive property, the adhesive force is accompanied by a change in adhesive force. In recent years, the thickness of the copper-clad laminate has been thinned, and the thickness has been diversified, leading to diversification of the substrate thickness of the protective film. The change in thickness of the substrate affects the adhesion, which is also a reason for the diversification of adhesion. It is easy to change the initial adhesive force of the protective film in accordance with these various conditions. However, there is a limitation in the conventional technique to control the adhesive force after the high-temperature compression, and such problems are desired to be improved.

Patent Document 1: Japanese Unexamined Patent Publication No. 2000-044896 Patent Document 2: Japanese Unexamined Patent Publication No. 2006-022313 Patent Document 3: Republic of Korea Patent Application No. 2007-0007622

An object of the present invention is to protect a flexible circuit board that can prevent surface contamination and deformation of the flexible circuit board as an adhesive by effectively controlling the adhesive force after initial and high temperature compression, including an acrylic resin with a hydroxy functional group, a curing agent mixture and a plasticizer. It is providing the adhesive composition for films.

Another object of the present invention is to provide a flexible circuit board protective film using the composition.

The pressure-sensitive adhesive composition for a flexible circuit board protective film of the present invention for achieving the above object is based on 100 parts by weight of the acrylic resin having a hydroxy functional group; 6 to 15 parts by weight of a mixture of toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) based hardener; And 0.1 to 10 parts by weight of a plasticizer having an ester value of 100 or more.

It is preferable that the ratio of the toluene diisocyanate (TDI) system and the hexamethylene diisocyanate (HDI) system of the isocyanate type hardening | curing agent of the said hardening | curing agent mixture is 1: 0.5-1: 6.

The plasticizer is selected from the group consisting of trioctyl trimellitate, dibutyl phthalate, diisononyl adipic acid, bis (2-butoxyethyl) adipic acid, acetyltributyl citrate and bis (2-butoxyethyl) phthalate. It is preferable that it is 1 or more types selected.

The flexible circuit board protective film of the present invention is composed of a base film and an adhesive layer applied to one or both surfaces of the base film, wherein the adhesive layer is based on 100 parts by weight of the acrylic resin having a hydroxy functional group; 6 to 15 parts by weight of a mixture of toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) based hardener; And 0.1 to 10 parts by weight of a plasticizer having a ester value of 100 or more.

It is preferable that the adhesive layer changes the adhesive force according to the peeling rate according to the following Equation 1:

[Equation 1]

F ₁ / F ₂ <2

Wherein F ₁ is the adhesive force at the peeling speed of 30 m / min and F ₂ is the adhesive force at the peeling speed of 0.3 m / min.

It is preferable that the adhesive force change according to the temperature of the adhesive layer follows the following Equation 2:

&Quot; (2) &quot;

1 <F ₃ <2,

1 <F ₄ <2

In the above formula, F ₃ = B / A, which is the ratio of the adhesive force (B) at 100 ° C. lamination to the adhesive force (A) at room temperature, and F ₄ = C / B, the adhesive force at 100 ° C. lamination ( It is ratio (C / B) of adhesive force C after high temperature compression with respect to B).

It is preferable that the said adhesion layer is 5-20 micrometers in thickness after drying of the said adhesive composition.

Preferably, the adhesive layer has a gel fraction of 90% or more as measured by Equation 3 below:

&Quot; (3) &quot;

Gel fraction = m / M * 100

Wherein M is the mass of the entire pressure sensitive adhesive and m is the mass of the gelled portion.

It is preferable that the adhesive layer is 10-35 gf / 25mm of adhesive force after high temperature compression.

It is preferable that the base film is a heat resistant film having a thickness of 10 to 100 µm.

The flexible circuit board protective film according to the present invention can effectively control the adhesion after initial and high temperature compression to prevent surface contamination and deformation of the flexible circuit board as an adherend. In addition, it is possible to minimize the surface contamination due to the etching liquid infiltration during the circuit printing process of the flexible circuit board and the increase of the adhesive force in the high temperature compression process to prevent the transfer of the adhesive to the flexible product after peeling and damage to the product. It is also advantageous for high speed peeling and can increase workability.

The pressure-sensitive adhesive composition for a flexible circuit board protective film of the present invention is based on 100 parts by weight of an acrylic resin having a hydroxy functional group; 6 to 15 parts by weight of a mixture of toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) based hardener; And 0.1 to 10 parts by weight of a plasticizer having an ester value of 100 or more.

The acrylic resin having a hydroxy functional group as a constituent of the pressure-sensitive adhesive composition used in the present invention is a copolymer of a conventional acrylic monomer having no hydroxy group functional group and an acrylic monomer having a hydroxy functional group. As a typical acryl-type monomer which does not have the said hydroxyl group functional group, for example, methyl acrylate, ethyl acrylate, butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, isooctyl acrylate, cyclohexyl acryl Acrylic acid alkyl esters such as latex, benzyl acrylate and the like; Methacrylic acid such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, benzylhexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, and the like Alkyl esters, and the like, which may be used alone or in combination of two or more. If desired, vinyl acetate, styrene, acrylonitrile, and the like may be added as copolymerization monomers; In addition, monomers containing carboxylic acid groups such as acrylic acid, methacrylic acid, maleic anhydride and itaconic acid may be added; It is also possible to use a mixture of acryl amides such as N-methylol acrylamide, acrylamide, methacrylamide, glycidylamide and the like.

As an acryl-type monomer which has the said hydroxy functional group, For example, hydroxy methyl (meth) acrylate, 1-hydroxy ethyl (meth) acrylate, 2-hydroxy ethyl (meth) acrylate, 1-hydroxy butyl ( Meta) acrylate, 2-hydroxy butyl (meth) acrylate, 3-hydroxy butyl (meth) acrylate, 4-hydroxy butyl (meth) acrylate, 1-hydroxy propyl (meth) acrylate, 2 -Hydroxy propyl (meth) acrylate, 3-hydroxy propyl (meth) acrylate and the like. These may be used alone or in combination of two or more. Neopentyl glycol diacrylate, 1,6-hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, trimethylolpropane acrylate, etc. It is also possible to use acrylic acid derivatives such as polyfunctional acrylates alone or in combination with a single functional acrylic acid derivative.

In the above, the ratio of the acrylic monomer having a hydroxy functional group is preferably 4 to 12 relative to the total weight of the monomer. If the ratio of the acrylic monomer having a hydroxy functional group does not reach 4 parts by weight, there is a possibility that the adhesive layer may be transferred to the adherend due to the low curing density, and if it exceeds 12 parts by weight, the gelation proceeds rapidly when mixing with the curing agent to As the pot life is reduced, the workability is lowered and the uniformity of the coating surface by the gelled portion is not preferable.

The acrylic resin having a hydroxy functional group preferably has a weight average molecular weight of 100,000 to 3 million, preferably 40 to 1 million. When the weight average molecular weight is less than 100,000 may cause cohesive failure, and when the weight average molecular weight exceeds 3 million, the workability becomes worse due to the viscosity increase. In addition, the glass transition temperature of the acrylic resin having a hydroxy functional group is preferably -20 ~ -70 ℃. If the glass transition temperature is less than -70 ℃, the adhesive force after the high-temperature compression is greatly increased, peeling is not easy, if the glass transition temperature exceeds -20 ℃ due to the increase of the elastic modulus is weak adhesive strength at room temperature or 100 ℃ due to the increase in reliability There is a disadvantage.

The pressure-sensitive adhesive composition for a flexible circuit board protective film of the present invention comprises 100 parts by weight of an acrylic resin having a hydroxy functional group; 6 to 15 parts by weight of a mixture of toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) based hardener. When the curing agent mixture is less than 6 parts by weight, the adhesive strength after high temperature compression is increased, the cohesive failure of the adhesive occurs, transfer occurs to the substrate, and when it exceeds 15 parts by weight, the initial adhesive force is low, so that the lifting occurs after the high-temperature treatment. Penetration will occur

In addition, the curing agent mixture is toluene diisocyanate (TDI) system and hexamethylene diisocyanate (HDI) system has a weight ratio of 1: 0.5 ~ 1: 6, by adjusting the ratio between the two curing agents appropriately to adjust the initial adhesive strength to the desired level and high temperature The increase in adhesive force after compression can be controlled. When the mixing ratio of the curing agent is less than 1: 0.5 or more than 1: 6, the adhesive force after high temperature compression increases, cohesive failure of the adhesive occurs, transfer occurs to the substrate, and deformation of the CCL occurs.

As a plasticizer of the adhesive composition which concerns on this invention, it is preferable that ester value is 100 or more and contains 0.1-10 weight part. When it exceeds 10 parts by weight, the elasticity modulus of the adhesive layer is lowered, so that the increase in the adhesive strength during high temperature compression is not possible, and it is impossible to use it, and transfer of the plasticizer to the surface of the adherend may occur. If it is 0.1 or less, it is disadvantageous for high speed peeling.

The plasticizer is a plasticizer having an ester value of 100 or more. The ester value is defined as the number of mg of potassium hydroxide required to completely saponify the ester contained in 1 g of the sample. When the plasticizer having an ester value of 100 or more is mixed with the composition, it has excellent compatibility and hardly transfers to the surface of the flexible circuit board, thus contaminating the surface of the adherend and advantageously for high speed peeling. Specific examples include trioctyl trimellitate, dibutyl phthalate, diisononyladipic acid, bis (2-butoxyethyl) adipic acid, acetyltributyl citrate, bis (2-butoxyethyl) phthalate, and the like. These may be used alone or in combination of two or more.

The flexible circuit board protective film of the present invention is composed of a base film and an adhesive layer applied to one or both surfaces of the base film, wherein the adhesive layer is based on 100 parts by weight of the acrylic resin having a hydroxy functional group; 6 to 15 parts by weight of a mixture of toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) based hardener; And 0.1 to 10 parts by weight of a plasticizer having an ester value of 100 or more.

As the base film, a heat resistant film having a thickness of 10 to 100 μm is used, and the material may include polyester resins such as polyethylene terephthalate, polybutyrene terephthalate, polyethylene naphthalate, and polybutyrene naphthalate; Polyimide resin; Acrylic resin; Styrene resins such as polystyrene and acrylonitrile-styrene; Polycarbonate resin; Polylactic acid resin; Polyurethane resin; Etc. may be used. In addition, polyolefin resin such as polyethylene, polypropylene, ethylene-propylene copolymer; Vinyl resins such as polyvinyl chloride and polyvinylidene chloride; Polyamide resins; Sulfonic resin; Polyether-ether ketone resin; Allylate series resin; Or a blend of the above resins is preferred. It is preferable to use a polyethylene terephthalate (PET) film among these.

The pressure-sensitive adhesive composition on one side or both sides of the base film is added to the composition, mixed under appropriate time / temperature conditions, and then coated to prepare a flexible circuit board protective film of the invention. The pressure-sensitive adhesive composition uses a solvent in consideration of the workability when coating, the solvent used should be capable of dissolving the pressure-sensitive adhesive composition and the type is acetone, toluene, xylene, ethanol, isobutanol, isopropanol, cyclohexanone, Methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate and the like. The solvents may be used alone or in combination of two or more thereof. In addition, the method of applying the pressure-sensitive adhesive composition is not particularly limited, and can be used using a coating method known in the art such as die coating method, gravure coating method, knife coating method, bar coating method. It is preferable to select in consideration of surface roughness, thickness uniformity, etc. of an adhesion layer. Drying conditions should take into account the heat resistance and reaction conditions of the solvent and resin used, the degree of drying, and can form an adhesive layer by treating at least 100 minutes at a temperature of 100 ℃ or more.

In the flexible circuit board protective film of the present invention, the pressure-sensitive adhesive layer is characterized in that the change in the adhesive force according to the peeling rate is according to the following equation (1):

[Equation 1]

F ₁ / F ₂ <2

In the above formula, F ₁ is the adhesive force at the peeling speed of 30 m / min, F ₂ is the adhesive force at the peeling speed of 0.3 m / min.

From the above formula, the adhesive force at high speed was limited to less than twice the adhesive force at low speed. For the sake of workability, in general, as the peeling speed increases, the adhesive force increases, and inevitably, the peeling speed of the protective film is inevitably low, and to increase the speed. There is a limit as to the increase in adhesive strength. In order to solve this problem, it is essential to limit the increase in adhesive force according to the peeling rate as in Equation 1 above. On the other hand, when the ratio of F ₁ / F ₂ is increased to 2 or more, difficulty in peeling occurs. In fact, the width of the flexible printed circuit board cut in the sheet state is about 10 times the peeling standard such as ASTM, and thus the peeling force is also 10 times the peeling force shown in the examples. Therefore, the increase of peel force should be suppressed as possible, and the ratio of F ₁ / F ₂ should be limited to 2 or less.

In addition, the adhesive force change according to the temperature of the adhesive layer is characterized in that according to the following equation (2):

&Quot; (2) &quot;

1 <F ₃ <2,

1 <F ₄ <2

In the above formula, F ₃ = B / A, which is the ratio of the adhesive force (B) at 100 ° C. lamination to the adhesive force (A) at room temperature, and F ₄ = C / B, the adhesive force at 100 ° C. lamination ( It is ratio (C / B) of adhesive force C after high temperature compression with respect to B).

In the above, F ₃ means the ratio of the initial adhesive force. Since the temperature at the time of lamination differs depending on the manufacturer at the ratio of lamination at room temperature and 100 ℃, it was introduced to reduce the error of adhesion to this. F ₃ is 1, the wettability turns out, because the storage modulus of the adhesive is reduced with increasing temperature there is no possibility in practice occur, F ₃ is the peeling strength rise in the temperature and conditions of the high pressure of the hot compression step, if two or more equivalent or less It is not desirable to do so.

In the above formula, F ₄ represents the change in adhesive strength after high temperature compression. In general adhesives, when the adhesive is compressed at high temperature, the increase in peeling force is about 3 to 5 times higher, which causes wrinkles or curls of CCL to occur. Occasionally, residue may occur. When the initial adhesive force is lowered due to such a problem, a problem occurs in that bubbles are introduced or peeled off during process flow. Therefore, the increase in adhesion after high-temperature compression should be effectively controlled. When F ₄ is 1 or less, there is no likelihood of occurrence as in F3, and when F ₄ is 2 or more, peeling force is increased so that the removal of the protective film is not easy, and thus the above-mentioned problems may occur.

The adhesive layer of the flexible circuit board protective film according to the present invention preferably has a thickness of 5 to 20 μm after drying of the pressure-sensitive adhesive composition. If the thickness is greater than 20 μm, the adhesive layer is thick, and thus the adhesive force is increased at high temperature compression. If the thickness is less than 5 μm, the thickness is thin, the wettability decreases, and thus the adhesion is not easy during initial lamination.

It is preferable that the adhesive layer is 10-35 gf / 25mm of adhesive force after high temperature compression. If the adhesive force exceeds 35g, it may cause a defect (curl, wrinkling, residue, etc.) of the CCL during peeling, and if it is less than 10g, the initial adhesive force may be low, thereby causing bubbles and peeling problems during process flow.

The adhesive layer preferably has a gel fraction of 90% or more, as measured by Equation 2 below:

&Quot; (3) &quot;

Gel fraction = m / M * 100

Wherein M is the mass of the entire pressure sensitive adhesive and m is the mass of the gelled portion. In order to prevent the residue of the adhesive, the gel fraction should be increased as much as possible. For adhesives used in protective films, the gel fraction should be kept above 90%. In particular, since the protective film of the present invention is used at high temperatures and pressures, when the gel fraction is 90%, residues or unreacted monomers due to cleavage of the polymer chains, or elution of some solvents stuck in the polymer chains without evaporation, etc. Sometimes problems arise. In this case, bubbles or peeling may occur and problems of CCL surface contamination may occur.

Hereinafter, the configuration and effects of the present invention will be described in more detail with reference to Examples and Comparative Examples. However, this embodiment is only an example for explaining the present invention more specifically, the scope of the present invention is not limited to these examples.

Example 1

1. Synthesis of Acrylic Resin Having Hydroxy Functional Group

In order to prepare an acrylic adhesive composition, 50 parts by weight of 2-ethylhexyl acrylate, 38 parts by weight of n-butyl acrylate, 1 part by weight of acrylic acid in a 1 L reactor equipped with a refrigeration device under nitrogen gas reflux and easy temperature control, A monomeric mixture consisting of 3 parts by weight of isooctyl acrylate and 8 parts by weight of 2-hydroxyethyl acrylate was added, and 300 parts by weight of ethyl acetate was injected into the solvent. Thereafter, nitrogen gas was purged for 30 minutes while stirring with a stirrer to remove oxygen. Thereafter, the reactor was maintained at 60 ° C, and 0.03 parts by weight of azobisisobutyronitrile was added to the mixture as a reaction initiator, and reacted for 8 hours. An acrylic air having a glass transition temperature of about -50 ° C and a weight average molecular weight of 600,000 The coalescence was synthesized.

2. Preparation of pressure-sensitive adhesive composition

50 parts by weight of methyl ethyl ketone (MEK), which is a solvent, is diluted with respect to 100 parts by weight of an acrylic resin having a hydroxy functional group, and toluene diisocyanate (TDI) (Cosmotech Co., Ltd. NA-1045L) based on an isocyanate curing agent A total of 8 parts by weight of hexamethylene diisocyanate (HDI) (Cosmotech Co., Ltd. NA-24T) system was added in a ratio of 1: 3, respectively, and 2 parts by weight of trioctyl trimellitate as a plasticizer were sequentially added, followed by uniform stirring to prepare an acrylic pressure-sensitive adhesive composition. Prepared.

3. Manufacture of surface protection film

The acrylic pressure-sensitive adhesive composition prepared above was coated on PET, a biaxially stretched polyester film having a thickness of 50 μm using a bar coater, and dried at 150 ° C. for 2 minutes to obtain a uniform adhesive layer having a thickness of 10 μm. The polyester-based release film was laminated using a 2 kgf / cm pressure and a speed of 7 mpm, and aged at 50 ° C. for 3 days to obtain a protective film for a flexible circuit board process having excellent heat resistance.

[Example 2]

50 parts by weight of methyl ethyl ketone (MEK), which is a solvent, was diluted with respect to 100 parts by weight of the acrylic resin polymerized in Example 1, and toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI), which is an isocyanate curing agent, as a curing agent. ) 8 parts by weight in total ratio of 1: 1.7 content, 5 parts by weight of trioctyl trimellitate as a plasticizer was sequentially added and stirred uniformly to prepare an acrylic pressure-sensitive adhesive composition to protect the flexible circuit board process as in Example 1 A film was prepared.

[Example 3]

50 parts by weight of methyl ethyl ketone (MEK), which is a solvent, was diluted with respect to 100 parts by weight of the acrylic resin polymerized in Example 1, and toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI), which is an isocyanate curing agent, as a curing agent. ) 14 parts by weight in a total ratio of 1: 1, 7 parts by weight of trioctyl trimellitate as a plasticizer was added sequentially and uniformly stirred to prepare an acrylic pressure-sensitive adhesive composition to protect the flexible circuit board process as in Example 1 A film was prepared.

Comparative Example 1

A protective film for a flexible circuit board process was manufactured in the same manner as in Example 1, except that 6 parts by weight of toluene diisocyanate (TDI) -based curing agent alone and 2 parts by weight of trioctyl trimellitate were mixed with a plasticizer.

Comparative Example 2

In the same manner as in Example 1, except that toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) based curing agents were mixed in an amount of 1: 2, and 18 parts by weight of total and 5 parts by weight of trioctyl trimellitate as a plasticizer. A surface protective film for a flexible circuit board process was prepared.

[Comparative Example 3]

In the same manner as in Example 1, except that 9 parts by weight of toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) based curing agents were mixed in a 1: 8 content ratio and 7 parts by weight of trioctyl trimellitate as a plasticizer. A surface protective film for a flexible circuit board process was prepared.

[Comparative Example 4]

Surface protection for the flexible circuit board process in the same manner as in Example 1 except that toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) curing agents were mixed in the same ratio and content as Example 1 and no plasticizer was added. A film was prepared.

[Comparative Example 5]

The same method as in Example 1, except that toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) based curing agent were mixed in the same ratio and content as in Example 2, and 11 parts by weight of trioctyl trimellitate was added as a plasticizer. The surface protection film for the flexible circuit board process was prepared.

For the protective film for the flexible circuit board process prepared in the Examples and Comparative Examples using the following experimental method was confirmed the physical properties and properties, and the results are summarized in Table 1 and 2.

[Property evaluation]

1. Initial adhesion measurement

A protective film for the flexible circuit substrate process manufactured in the above Examples and Comparative Examples was laminated to a two-layer CCL (trade name: PI 38N - CCS 08 E0A) manufactured by Toray High-Tech Materials Co., At a pressure of ² kgf / cm &lt; 2 &gt;, at a rate of 7 mpm, and left at room temperature for 60 minutes. After that, a specimen was prepared by cutting 25 mm * 250 mm in the MD direction, and the sample was subjected to a 180 ° peel test, and the peeling speeds were 0.3 m / min and 30 m / min, respectively.

2. Adhesion after high temperature compression

The protective film for the flexible circuit substrate process fabricated in the above Examples and Comparative Examples was applied to a 2-layer CCL (trade name: PI-38N CCS-08 E0A) manufactured by Toray Hi-tech Materials Co., cm &lt; ^{2 &} gt ;, at a rate of 7 mpm, and left at room temperature for 60 minutes. The specimens were pressed in a high-temperature compressor at a temperature of 160 ° C and a pressure of 9 MPa for 60 minutes, and then specimens were prepared in the MD direction of 25 mm * 250 mm and left at room temperature for 60 minutes. Thereafter, the peeling angle of the sample was 180 ° and the peeling rate was set at 0.3 m / min and 30 m / min, respectively.

3. Comparison of adhesive force ratio according to peeling speed

Obtain the adhesive force of the protective film for flexible circuit board process after lamination at 100 ℃ and the high temperature compression at 30 m / min and 0.3 m / min, respectively, and leave them at the values defined in Equation 1 above. The ratio of each adhesive force was calculated | required.

4. Comparison of adhesive force ratio by lamination temperature and compression

Obtain the initial adhesive strength and the adhesive strength after high-temperature compression of the flexible circuit board process protective film laminated at room temperature and 100 ° C, respectively, and set them as the values defined in Equation 2 above to obtain the values of F _{1 and} F _{2 ,} which are ratios of each adhesive force. Was:

5. Comparative measurement of gel fraction of adhesive layer

Since it is difficult to separate the adhesive from the protective film separately, it is difficult to directly measure the gel fraction. Thus, the pressure-sensitive adhesive composition was coated on a release film, dried and aged, and then about 0.2 g of the adhesive layer was taken out and stored in a 200-mesh stainless steel net. Then, 100 g of ethyl acetate was added and left at room temperature for 24 hours. Thereafter, the remaining gel was filtered out and dried in an oven at 50 ° C for 24 hours. Then, the gel fraction was determined according to the above-described formula (3)

6. Comparison of Protection Film Lifted Condition

Using a 100 ° C heated sheeting machine, the protective protective film for the flexible circuit board process laminated at a pressure of 2kgf / cm ² , the speed of 7mpm was left at room temperature for 60 minutes, and then cut into 150mm * 150mm size using small bean curd. After that, the sample was left to stand at room temperature for 60 minutes, and then visually confirmed whether the protective film and the polyimide surface of the CCL were lifted and evaluated by the following criteria.

(Circle): Lifting of a polyimide surface and an adhesion layer does not generate | occur | produce.

X: A part of lifting of a polyimide surface and an adhesive layer generate | occur | produces.

7. Comparative measurement of adhesive transfer after peeling

After high temperature compression, the sample was left at room temperature for 60 minutes, and when the half of the adhesive film was peeled off by hand slowly and the other half was quickly peeled off in a T-shape, the naked eye and the microscope checked whether the adhesive residue remained on the polyimide surface of the CCL. Evaluation was made based on the criteria.

(Circle): The transcription | transfer of the adhesive which can be observed with a microscope and visually does not generate | occur | produce on a polyimide surface.

X: The transcription | transfer of the adhesive which can be observed by a microscope and the naked eye also generate | occur | produces at least partially on the polyimide surface.

8. Comparison measurement of etchant penetration during etching

The protective film for the flexible circuit board process prepared in the above Examples and Comparative Examples was manufactured by Toray Advanced Materials Co., Ltd. in a two-layer CCL (trade name: PI-38N CCS-08 E0A) at a pressure of ² kgf / cm ² at 100 ° C. and 7 mpm. It was laminated at the speed of and left for 60 minutes. After that, cut the sample into 150mm * 150mm size, immerse it in the etching solution for FPCB circuit printing, and leave it for 24 hours. After confirming that all the copper foil was melted, remove it and visually check whether there was liquid penetration between the imide surface of CCL and the adhesive layer of protective film. It confirmed and evaluated by the following criteria.

◎: No penetration of etching solution occurs and appearance of protective film is good.

(Circle): Penetration of the etchant occurred in the edge part, but the appearance of the protective film was good.

(Triangle | delta): Penetration of an etchant arises in the edge part, and the appearance state of a protective film is bad.

X: Penetration of etching liquid occurs overall and appearance of protective film is poor.

9. Comparison measurement of CCL deformation after peeling

After leaving the sample at room temperature for 60 minutes after high temperature compression, visually check whether the appearance damage such as CCL wrinkle occurs when peeling half of the adhesive film by hand slowly and quickly peeling off the other half in T-shape. It evaluated on the basis of.

○: No appearance damage of CCL.

X: Appearance damage of CCL occurs.

Example 1 Example 2 Example 3 Adhesive layer Acrylic resin 100 copies 100 copies 100 copies Adhesive layer Hardener TDI system Part Two Part Three Part 7 Adhesive layer Hardener HDI system Part 6 Part 5 Part 7 Plasticizer 2 5 7 Initial adhesion
(gf / 25 mm) Room temperature 20 16 5 100 ℃ 22 17 8 Adhesion after high temperature compression
(gf / 25 mm) 31 27 10 Adhesion Ratio According to Peeling Rate
F ₁ / F ₂ After 100 ℃ lamination 1.8 1.5 1.5 After high temperature compression 1.9 1.4 1.3 Adhesive strength ratio according to temperature and compression F ₃ 1.1 1.1 1.6 F ₄ 1.4 1.6 1.3 Gel fraction (%) 95.2 94.9 92.3 Lifted after high temperature treatment ○ ○ ○ Adhesive transfer after peeling ○ ○ ○ Etchant penetration ◎ ◎ ○ CCL variant ○ ○ ○

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Adhesive layer Acrylic resin 100 copies 100 copies 100 copies 100 copies 100 copies Adhesive layer Hardener TDI system Part 6 Part 6 chapter 1 Part Two Part Three Adhesive layer Hardener HDI system Part 0 Part 12 Part 8 Part 6 Part 5 Plasticizer 2 5 7 0 11 Initial adhesion
(gf / 25 mm) Room temperature 25 10 18 23 16 100 ℃ 28 13 23 27 19 Adhesion after high temperature compression
(gf / 25 mm) 39 48 78 34 58 Adhesion Ratio According to Peeling Rate
F ₁ / F ₂ After 100 ℃ lamination 1.7 1.5 1.4 1.9 1.5 After high temperature compression 1.7 1.4 1.6 2.4 1.5 Adhesive strength ratio according to temperature and compression F ₃ 1.1 1.3 1.3 1.2 1.2 F ₄ 1.4 3.7 3.4 1.3 3.1 Gel fraction (%) 96.1. 94.0 91.1 96.3 88.5 Lifted after high temperature treatment ○ ◎ ◎ ○ ◎ Adhesive transfer after peeling ○ ○ × ○ × Etchant penetration ◎ ○ ○ ◎ ○ CCL variant × × × ○ ×

From the above Table 1 and Table 2, the protective film using the acrylic pressure-sensitive adhesive composition of Examples 1 to 3 according to the present invention is well controlled compared to Comparative Examples 1 to 5 and the adhesive strength after high-temperature compression is better than high-speed peeling Advantage can be seen. Such well controlled adhesive force and excellent high-speed peeling characteristics can provide a surface protection film for a flexible circuit board process. That is, in the embodiment according to the present invention by maintaining the initial adhesive force at an appropriate level to secure the adhesive force with the CCL when laminating to ensure the reliability of the etching and plating process, while controlling the increase in adhesive strength after high temperature compression, the adhesive transfer and wrinkle during peeling And it is possible to prevent the curl, etc. of the soft product and can increase the workability due to the excellent high-speed peelability.

In the above description of the preferred embodiment of the present invention, the present invention is not limited thereto, and it is easy for those skilled in the art to make various modifications and modifications within the scope of the present invention. It is obvious that the claims belong to the appended claims.

The present invention relates to a high heat-resistant pressure-sensitive adhesive used in the manufacturing conditions of high temperature and high pressure can be used for the flexible circuit board protective film.

Claims (12)

delete delete delete In the flexible circuit board protective film consisting of a base film and an adhesive layer applied to one or both sides of the base film,
The adhesive layer is based on 100 parts by weight of an acrylic resin having a hydroxy functional group; Toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) curing agent mixture 6 to 15, wherein the ratio of toluene diisocyanate (TDI) and hexamethylene diisocyanate (HDI) is 1: 0.5 to 1: 6 by weight. Parts by weight; And 0.1 to 10 parts by weight of a plasticizer having an ester value of 100 or more;
The adhesive layer is a flexible circuit board protective film, characterized in that the change in the adhesive force according to the peeling rate according to the following formula (1):
[Equation 1]
F ₁ / F ₂ <2
Wherein F ₁ is the adhesive force at the peeling speed of 30 m / min and F ₂ is the adhesive force at the peeling speed of 0.3 m / min. delete The flexible circuit board protective film of claim 4, wherein the adhesive force change according to the temperature of the adhesive layer is according to Equation 2.
&Quot; (2) &quot;
1 <F ₃ <2,
1 <F ₄ <2
In the above formula, F ₃ = B / A, which is the ratio of the adhesive force (B) at 100 ° C. lamination to the adhesive force (A) at room temperature, and F ₄ = C / B, the adhesive force at 100 ° C. lamination ( It is ratio (C / B) of adhesive force (C) at 160 degreeC lamination with respect to B). delete The flexible circuit board protective film of claim 4, wherein the adhesive layer has a thickness of 5 to 20 μm after drying of the adhesive composition. The flexible circuit board protective film of claim 4, wherein the adhesive layer has a gel fraction of 90% or more as measured by Equation 3 below:
&Quot; (3) &quot;
Gel fraction = m / M * 100
Wherein M is the mass of the entire pressure sensitive adhesive and m is the mass of the gelled portion. The flexible circuit board protective film of claim 4, wherein the adhesive layer has a pressure of 10 to 35 gf / 25 mm after pressing for 60 minutes at a temperature of 160 ° C. and a pressure of 9 MPas. The flexible circuit board protective film of claim 4, wherein the base film is a heat resistant film having a thickness of 10 μm to 100 μm. The method of claim 4, wherein the plasticizer is trioctyl trimellitate, dibutyl phthalate, diisononyl adipic acid, bis (2-butoxyethyl) adipic acid, acetyltributyl citrate and bis (2-butoxyethyl ) The flexible circuit board protective film, characterized in that at least one selected from the group consisting of phthalates.