JP2016168688A - Release film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a release film which has an improved balance of releasability and followability, and is excellent in wrinkle resistance and stain resistance.SOLUTION: A release film has a release layer containing a polyester resin material on at least one surface. When one surface of the release layer of the release film is overlapped by the other surface in an opposite side to a surface having the release layer of the release film, the film is pressurized at a load of 1 kg for 0.5 minutes, then the one release film and the other release film are peeled from each other on the condition of a temperature of 25°C at a peeling speed of 300 mm/min, and a peeling charged voltage of the surface of the release layer of the one release film immediately after peeling is represented by Q, |Q| is 100 V or more and 1,000v or less.SELECTED DRAWING: None

Description

  The present invention relates to a release film.

  The release film is generally used when a molded product is manufactured or a laminate in which different materials are bonded together. Such a release film is flexible, for example, by bonding a coverlay film (hereinafter also referred to as “CL film”) to a flexible film (hereinafter also referred to as “circuit exposure film”) with an exposed adhesive by a hot press. It is used when manufacturing a printed circuit board (hereinafter also referred to as “FPC”). Specifically, the release film is used for the purpose of protecting the surface of the molded product or laminate when producing the molded product or laminate. Therefore, it has been conventionally required for the release film to improve two characteristics described below. The characteristic of the mold release film requested | required first is the ease of peeling of the said mold release film after manufacturing a molded article or a laminated body, ie, mold release property. The second required property of the release film is the adhesiveness of the release film to the surface of the molded product or the laminate, that is, the followability. Conventionally, various studies have been made to improve characteristics such as releasability and followability in such a release film.

  Examples of techniques that focus on improving the releasability of the release film and techniques that focus on improving followability include the following.

  Patent Document 1 discloses a polyester-based elastomer layer showing specific values for glass transition temperature and crystallization rate index, crystalline aromatic polyester and 1,4-cyclohexanedimethanol copolymerized polyethylene blended at a specific mass ratio. There is disclosed a release film comprising a polyester layer made of polyester which is made of terephthalate and has specific values for glass transition temperature and heat of crystal fusion.

  Patent Document 2 discloses a release film having a crystalline polyester layer showing specific values for the heat of crystal fusion and the crystallization speed index, and a polyester layer showing specific values for the heat of crystal fusion and the crystallization speed index. ing.

  Patent Document 3 discloses a polyester-based elastomer layer having specific values for a glass transition temperature and a crystallization rate index, a specific crystallization start temperature at a temperature rise, a temperature rise crystallization peak temperature, and a temperature rise crystallization heat amount. A release film having a copolyester layer exhibiting a value is disclosed.

JP 2011-88351 A JP 2011-88352 A JP 2011-245812 A

  As described above in the section of the background art, various studies have been made on improving the release property and followability even in the conventional release film.

However, in recent years, the technical level required for various properties of a release film has been increasing. This inventor discovered the following subjects regarding the conventional release film as described in patent documents 1-3.
In order to improve the followability of the release film, the conventional release film tends to lower the release property of the release film by reducing the storage modulus of the release film or the hardness of the release film surface. It was in. On the other hand, in order to improve the release property of the release film, the conventional release film increases the storage modulus of the release film or the hardness of the release film surface, thereby improving the followability of the release film. There was a tendency to go down. Thus, this inventor discovered that there existed a trade-off relationship between mold release property and followability in the conventional mold release film. In other words, the present inventor has found that there is room for improvement in the conventional release film in terms of improving both the release property and followability of the release film in a balanced manner. Although there were technologies that focused on improving releasability and technologies that focused on improving followability for release films, technologies that improve both releasability and followability in a balanced manner have been developed so far. It was not reported.

  In addition, the present inventor has found the following two problems concerning the conventional release film. The first problem is that, when a flexible printed circuit board is produced using a release film, the wrinkle resistance is reduced due to the occurrence of wrinkles in the release film during hot pressing. The second problem is that, when a flexible printed circuit board is produced using a release film, foreign matter such as dust is sandwiched between the laminate and the release film when performing hot pressing. The surface is contaminated.

  Then, this invention provides the release film excellent in the wrinkle resistance and non-contamination property while improving the balance of mold release property and followable | trackability.

  As a result of intensive research to achieve the above-mentioned problems, the present inventor has found that the scale of the release voltage on the release layer surface of the release film measured under specific conditions is a balance between the release property and the followability. The present invention was completed by obtaining the knowledge that it is effective as a design guideline for realizing a release film excellent in wrinkle resistance and non-staining properties.

According to the present invention, a release film having a release layer containing a polyester resin material on at least one surface,
The surface opposite to the surface having the release layer of the other release film was superposed on the release layer surface of one release film, and pressurized with a load of 1 kg for 0.5 minutes. Thereafter, the release layer surface of the one release film immediately after the one release film and the other release film are peeled off at a peeling speed of 300 mm / min at a temperature of 25 ° C. when the peeling electrification voltage amount was Q ₁ in,
A release film having | Q ₁ | of 100 v or more and 1000 v or less is provided.

  ADVANTAGE OF THE INVENTION According to this invention, while being excellent in the balance of mold release property and followable | trackability, the release film excellent in the wrinkle resistance and non-contamination property can be provided.

<Release film>
The release film in the present embodiment is a release film having a release layer containing a polyester resin material on at least one surface, and the release film surface of the other release film has another release layer. After the surface opposite to the surface having the release layer of the mold film is overlapped and pressurized with a load of 1 kg for 0.5 minutes, the one release film and the other release film are heated to a temperature. under conditions of 25 ° C., when the peeling electrification voltage quantity in the release layer surface of the release film of the one immediately after peeling at a peeling speed of 300 mm / min was _{Q 1,} | _{Q 1} | is less than or 100v 1000v Is. Thereby, the balance of the stable release property and followable | trackability of a release film can be improved.

  For example, in order to produce a molded product, the release film may be used by being disposed on the surface of an object formed of a material containing a thermosetting resin. In addition, the release film may be used by being placed on the surface of a film to be pressed when a CL film is bonded to the circuit exposed film via an adhesive by a hot press to obtain a laminate such as an FPC. Specifically, the release film is used by being placed on the surface of an object installed in a mold of a press molding machine. In addition, in order to manufacture a molded article and FPC, the press process in the state which has arrange | positioned the release film on the target object surface is required. In the present embodiment, a surface disposed on the surface of the object in the release film is a release surface.

  The present inventor has found that the following inconvenience occurs when a conventional release film is used. First, in the conventional release film, when the release film is peeled off from the surface of the object after hot pressing, the carboxyl group in the material that forms the surface (release surface) of the release layer, and the object In some cases, contaminants generated by reacting and interacting with unreacted functional groups in the material adhering to the surface may remain on the surface of the obtained molded product. Secondly, in a conventional release film, a part of the release film undulates at the time of hot pressing, or air enters between the release film and the object, so that the release film is released during the hot press. The followability was reduced by the occurrence of wrinkles in the mold film. Thirdly, in the conventional release film, the surface of the obtained molded product may be contaminated by foreign matters such as dust entering between the release film and the object during the hot pressing.

  As a result of intensive studies on the cause of the above-described inconvenience, the present inventor has found that there is room for improvement in the following three points. The first improvement is that good release characteristics cannot be obtained after using the release film. The second improvement is that a part of the release film does not wavy when the release film is used, and good followability cannot be obtained to the extent that the release film does not wrinkle when performing hot pressing. Is a point. A third improvement point is that the surface of the obtained molded product is contaminated by foreign matters such as dust entering between the release film and the object during the hot pressing.

As described above, the release film according to the present embodiment controls the value of the release voltage | Q ₁ | on the release layer surface of the release film measured under specific conditions for the release film. . As a result, when the release film is peeled off from the object after the hot press, it is possible to obtain a molded product of good quality with no contaminants or dust remaining on the surface and having a smooth surface shape. it can. As described above, the release film according to the present embodiment is excellent in the balance between the release property and the followability as compared with the conventional release film by controlling the value of the peeling voltage amount | Q ₁ |. , It can be excellent in wrinkle resistance and non-contamination.
In addition, the value of the peeling band voltage amount | Q ₁ | on the surface of the release layer of the release film measured under specific conditions shows a lower value as the release layer surface shape becomes smoother at the time of measurement.

In the release film according to the present embodiment, the value of the release voltage | Q ₁ | on the release layer surface of the release film measured under specific conditions is 100 v or more, preferably 110 v or more. . In this way, when the release film is used, the adhesion between the object and the release film is improved, and a part of the release film undulates, or the release film and the object. Air can be prevented from entering between the two. That is, by setting the lower limit value of the peeling voltage amount | Q ₁ | to the above numerical value or more, it is possible to obtain a release film that is more excellent in terms of followability and wrinkle resistance.

In the release film according to the present embodiment, the value of the release voltage | Q ₁ | on the release layer surface of the release film measured under specific conditions is 1000 v or less, preferably 800 v or less. . In this way, when the release film was used, the release film could not attract foreign substances such as dust, and thus was obtained when the release film was peeled off from the object after the hot press. It is possible to prevent foreign matters such as contaminants and dust from remaining on the surface of the molded product. That is, by setting the upper limit value of the peeling voltage amount | Q ₁ | to be equal to or less than the above numerical value, a release film that is more excellent in terms of release property and non-contamination property can be obtained.

In the release film according to this embodiment, the surface opposite to the surface having the release layer of the other release film is superimposed on the release layer surface of one release film, and the load is 1 kg. After pressurizing for 0.5 minutes, the one release film and the other release film are peeled off at a peeling speed of 300 mm / min under a temperature of 25 ° C., and 0.5 minutes have passed after peeling. when the charged voltage amount in the release layer surface of the release film of the one time was Q _2, the value of Q 2 _/ Q ₁ is preferably 1 or lower, more preferably, 0.1 or less, More preferably, it is 0.001 or less. By doing so, it is possible to prevent the carboxyl group of the material forming the release surface of the release film from reacting with and interacting with the unreacted functional group in the material forming the surface of the object. Molding and non-contaminating properties are further improved, and a molded product having a good quality with a smooth surface shape and a laminate such as FPC can be obtained. The lower limit value is not particularly limited, and a value close to 0 is more preferable.

  The surface 10-point average roughness (Rz) of the release surface of the release layer is preferably 0.1 μm or more from the viewpoint of obtaining stable release properties while ensuring the strength of the release layer. Is 0.5 μm or more, and most preferably 0.8 μm or more. On the other hand, from the viewpoint of suppressing the transfer of the surface roughness, the surface 10-point average roughness (Rz) of the release surface of the release layer is preferably 20 μm or less, more preferably 10 μm or less. Yes, most preferably 5 μm or less. The surface 10-point average roughness (Rz) can be measured according to JIS-B0601-1994. Further, the surface 10-point average roughness (Rz) according to the present embodiment refers to a numerical value of a surface (release surface) corresponding to the object side in the release film when the release film is disposed on the object.

  The average spacing (Sm) of the unevenness of the release surface of the release layer is preferably 180 μm or more, more preferably 195 μm or more, from the viewpoint of obtaining stable release properties while ensuring the strength of the release layer. It is. On the other hand, from the viewpoint of suppressing the transfer of the surface roughness, the average interval (Sm) of the unevenness is preferably 450 μm or less, more preferably 345 μm or less. In addition, the average space | interval (Sm) of an unevenness | corrugation can be measured according to JIS-B0601-1994. Moreover, the average interval (Sm) of the unevenness | corrugation which concerns on this embodiment points out the numerical value of the surface (release surface) which hits the target object side in a release film, when a release film is arrange | positioned at a target object.

  The arithmetic average roughness (Ra) of the release surface of the release layer is preferably 0.08 μm or more, more preferably from the viewpoint of obtaining stable release properties while ensuring the strength of the release layer. It is 0.14 μm or more. On the other hand, from the viewpoint of suppressing the transfer of the surface roughness, the arithmetic average roughness (Ra) is preferably 1 μm or less, and more preferably 0.78 μm or less. In addition, arithmetic mean roughness (Ra) can be measured according to JIS-B0601-1994. Further, the arithmetic average roughness (Ra) according to the present embodiment refers to a numerical value of a surface (release surface) corresponding to the object side in the release film when the release film is disposed on the object.

  The peel strength of the release surface of the release layer is preferably as low as possible, but is preferably 5 N / 50 mm or less, and more preferably 3 N / 50 mm or less. The peel strength can be measured, for example, by the following method. First, a circuit-exposed film in which a coverlay film is temporarily fixed with an adhesive is prepared and bonded so that a release surface of the release film faces the circuit-exposed film at a pressure of 195 ° C. and 6 MPa. A test piece is prepared by hot pressing for 2 minutes. Thereafter, a peel test is performed on the obtained test piece by applying a stress in the 180 ° direction at a speed of about 50 mm / sec using a tensile tester. The measurement of peel strength is preferably carried out immediately after hot pressing.

In the release film according to the present embodiment, the value of the ratio OTR ₁ / T between the oxygen transmission rate OTR ₁ of the release film and the thickness T of the release film at 25 ° C. and 65 RH% is preferably 5 ×. 10 ² cc / m ³ · day or more, more preferably 8.3 × 10 ² cc / m ³ · day or more, and most preferably 8.3 × 10 ³ cc / m ³ · day or more. is there. By doing so, the gas generated from the object at the time of hot pressing can be efficiently dispersed on the release film side. Therefore, when the value of OTR ₁ / T is set to the above lower limit value or more, the followability is deteriorated due to the influence of the gas generated from the object and the surface shape of the object is changed during the hot press. The release film can be further improved in terms of non-contamination. The oxygen transmission rate is measured according to Appendix B in JIS K7126-2, for example.

In the release film according to the present embodiment, the value of the ratio OTR ₁ / T between the oxygen transmission rate OTR ₁ of the release film and the thickness T of the release film at 25 ° C. and 65 RH% is preferably 9 × 10. ⁵ cc / m ³ · day or less, more preferably 8.3 × 10 ⁵ cc / m ³ · day or less. By carrying out like this, it can suppress effectively that air penetrate | invades between a target object and a release film from the press outer part at the time of hot press. Therefore, when the value of OTR ₁ / T is equal to or less than the above upper limit value, it is possible to suppress a decrease in followability due to air or gas entering between the object and the release film from the outside of the press machine. It is possible to obtain a release film that is more excellent in terms of property and non-contamination. That is, when the value of OTR ₁ / T is not more than the above upper limit value, it is possible to improve the balance between followability and releasability and to obtain a release film that is more excellent in terms of non-contamination. .

In the release film according to the present embodiment, the value of the oxygen permeability OTR ₁ of the release film at 25 ° C. and 65 RH% is preferably 1 cc / m ² · day or more, more preferably 10 cc / m. ² · day or more. By doing so, non-contamination can be improved during hot pressing, and for example, it is possible to realize an improvement in yield when manufacturing a precise flexible printed circuit board.

In the release film according to this embodiment, the value of the oxygen permeability OTR ₁ of the release film at 25 ° C. and 65 RH% is preferably 100 cc / m ² · day or less, more preferably 95 cc / m. ² · day or less. By doing this, it is possible to suppress deterioration in follow-up and contamination caused by air or gas entering from the outside and changing the surface shape of the object, thereby realizing an improvement in yield when manufacturing a flexible printed circuit board. be able to.

Then, when the release film according to the present embodiment, in which 180 ° C. the release film, the oxygen permeability of the release film was measured after heat pressing for 120 seconds at 60 kg / cm ² and OTR ₂ The oxygen permeability index calculated by the following formula (1) from the oxygen permeability OTR ₁ measured before hot pressing and the oxygen permeability OTR ₂ measured after hot pressing is preferably Is 55 or more, more preferably 60 or more. Further, the upper limit value of the oxygen transmission index is preferably 95 or less, and more preferably 90 or less. By making the value of the oxygen permeation index within the above numerical range, when manufacturing a molded product or a laminate by hot pressing, from the air that has entered from the outside of the press machine and the object remaining inside the press machine The influence of the generated gas can be further reduced. Therefore, for example, in the hot pressing process during the manufacture of the flexible printed circuit board, the followability and non-contamination can be improved, and the yield during the manufacturing can be improved.
Oxygen transmission index = (OTR ₂ / OTR ₁ ) × 100 (1)

  The release layer includes a polyester resin. Examples of this polyester resin include polyalkylene terephthalate resins such as polyethylene terephthalate resin (PET), polybutylene terephthalate resin (PBT), polytrimethylene terephthalate resin (PTT), and polyhexamethylene terephthalate resin (PHT). Examples thereof include polyester copolymer resins obtained by copolymerizing components. These may be used alone or in combination of two or more. Among these, it is preferable to use polybutylene terephthalate resin from the viewpoint of improving the balance between releasability and followability. The polyester resin may be a crystalline polyester resin or an amorphous polyester resin.

  Examples of the component to be copolymerized in the polyester copolymer resin obtained by copolymerizing other components include known acid components, alcohol components, phenol components, derivatives thereof having ester forming ability, polyalkylene glycol components, and the like.

  Known acid components that can be copolymerized include, for example, divalent or higher valent aromatic carboxylic acids having 8 to 22 carbon atoms, divalent or higher valent aliphatic carboxylic acids having 4 to 12 carbon atoms, and 2 Examples thereof include alicyclic carboxylic acids having a carbon number of 8 to 15 or more and those having an ester forming ability. Specific examples of the acid component that can be copolymerized include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, bis (p-carbodiphenyl) methaneanthracene dicarboxylic acid, 4-4′-diphenylcarboxylic acid, 1,2 -Bis (phenoxy) ethane-4,4'-dicarboxylic acid, 5-sodium sulfoisophthalic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, maleic acid, trimesic acid, trimellitic acid, pyromellitic acid, 1 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid and derivatives thereof having ester forming ability. These can be used alone or in combination of two or more.

  Examples of the alcohol component and / or phenol component that can be copolymerized include a divalent or higher valent aliphatic alcohol having 2 to 15 carbon atoms, a divalent or higher alicyclic alcohol having 6 to 20 carbon atoms, and a carbon number. Examples thereof include 6 to 40 divalent or higher aromatic alcohols, or derivatives thereof having phenol and ester forming ability. Specifically, ethylene glycol, propanediol, butanediol, hexanediol, decanediol, neopentyl glycol, cyclohexanedimethanol, cyclohexanediol, 2,2'-bis (4-hydroxyphenyl) propane, 2,2'- Examples thereof include compounds such as bis (4-hydroxycyclohexyl) propane, hydroquinone, glycerin and pentaerythritol, derivatives thereof having ester forming ability, and cyclic esters such as ε-caprolactone.

  Examples of the polyalkylene glycol component that can be copolymerized include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and random or block copolymers thereof, alkylene glycols of bisphenol compounds (polyethylene glycol, polypropylene glycol, poly And modified polyoxyalkylene glycols such as adducts such as tetramethylene glycol and random or block copolymers thereof.

  Among such polyester copolymer resins, a copolymer of a polyester resin material and a polyalkylene glycol component is preferable, more specifically, a copolymer of a polyester resin and polytetramethylene glycol, more specifically, Specifically, a copolymer of polybutylene terephthalate resin and polytetramethylene glycol is preferable. Thereby, an excellent release film can also be obtained from the viewpoint of plating property.

  The content of other components capable of copolymerization (especially polytetramethylene glycol) is preferably 5% by weight or more and 50% by weight or less, more preferably 10% by weight of the total polyester copolymer resin. % By weight or more and 40% by weight or less. When the content is not less than the above lower limit, it is possible to improve the followability of the release film to the object. Moreover, a mold release property can further be improved as content is below the said upper limit.

  For the release layer, in addition to polyester resin, antioxidants, slip agents, antiblocking agents, antistatic agents, coloring agents such as dyes and pigments, additives such as stabilizers, impact resistance of fluororesins, silicone rubber, etc. An inorganic filler such as a property-imparting agent, titanium oxide, calcium carbonate, or talc may be included.

  The thickness of the release layer is preferably 5 μm or more, more preferably 10 μm or more, from the viewpoint of improving the embedding property to the molded product. On the other hand, from the viewpoint of obtaining an appropriate strength, the thickness of the release layer is preferably 100 μm or less, more preferably 50 μm or less, and most preferably 30 μm or less.

  The intrinsic viscosity of the resin constituting the release layer of the release film is preferably 0.3 dl / g or more, more preferably 0.5 dl / g or more, from the viewpoint of improving the film formability. . On the other hand, the intrinsic viscosity of the resin constituting the release layer is preferably 2.5 dl / g or less, more preferably 2.0 dl / g or less, from the viewpoint of reducing the load during the production of the release film. Yes, most preferably 1.5 dl / g or less.

  The acid value of the resin constituting the release layer of the release film is preferably 1 or more, more preferably 3 or more, from the viewpoint of improving the balance between peelability and followability. On the other hand, the acid value of the resin constituting the release layer is preferably 40 or less, more preferably 30 or less, and most preferably 25 or less, from the viewpoints of heat resistance and film formability. In addition, the acid value in this embodiment points out the value according to JISK0070 (1992 formula).

  The release film in the present embodiment may have a release layer including a polyester resin on at least one surface, but a multilayer including a release layer and another layer different from the release layer. It is preferable to form a structure. Specifically, the release film may have a release layer containing a polyester resin on both sides of the release film depending on the application. When using the release film in this case, it is called a direction release layer having a surface in contact with an object, and the other surface is sometimes called a sub-release layer. Moreover, the release film may further have a cushion layer in contact with the release layer. The release film may have a three-layer structure in which a release layer, a cushion layer, and a sub-release layer are laminated in this order. By having such a sub-release layer, when it is hot-pressed by a press machine, the releasability from the hot plate is improved, and the productivity in the production of laminates such as molded bodies and FPCs is improved. Can do. The plurality of release layers may be formed of the same material or may be formed of different materials as long as the material includes a polyester resin. Further, the plurality of release layers may have different thicknesses.

  The surface 10-point average roughness (Rz) of the release surface of the secondary release layer is preferably 0.1 μm or more from the viewpoint of obtaining stable release properties while ensuring the strength of the secondary release layer. More preferably, it is 0.5 μm or more, and most preferably 0.8 μm or more. On the other hand, from the viewpoint of suppressing the transfer of the surface roughness, the surface 10-point average roughness (Rz) of the release surface of the sub-release layer is preferably 20 μm or less, more preferably 10 μm or less. And most preferably 5 μm or less. The surface 10-point average roughness (Rz) can be measured according to JIS-B0601-1994. Moreover, the said surface 10-point average roughness (Rz) points out the numerical value of the surface (release surface) on the opposite side to the target object side in a release film, when a release film is arrange | positioned at a target object.

  The cushion layer imparts cushioning properties to the entire release film by using a resin having flexibility. As a result, when the release film is used, heat and pressure from the press hot plate are easily transmitted to the adherend, and the adhesion and followability between the release film and the adherend are further improved. it can.

  As a resin material for forming the cushion layer, an α-olefin polymer such as polyethylene and polypropylene, an α-olefin copolymer having ethylene, propylene, butene, pentene, hexene, methylpentene and the like as a polymer component, Engineering plastics resins such as polyethersulfone and polyphenylene sulfide are listed. These may be used alone or in combination. Of these, α-olefin copolymers are preferred. Examples of the α-olefin copolymer include a copolymer of an α-olefin such as ethylene and a (meth) acrylic acid ester, a copolymer of ethylene and vinyl acetate, and a copolymer of ethylene and (meth) acrylic acid. Examples thereof include polymers and partially ion cross-linked products thereof. Furthermore, from the viewpoint of obtaining a good cushion function, an α-olefin- (meth) acrylic acid ester copolymer such as ethylene alone, or polybutylene terephthalate and 1,4 cyclohexanedimethanol copolymer polyethylene terephthalate And a mixture of an α-olefin polymer and an α-olefin- (meth) acrylate copolymer such as ethylene. For example, a mixture of ethylene and ethylene-methyl methacrylate copolymer (EMMA), a mixture of polypropylene (PP) and ethylene-methyl methacrylate copolymer (EMMA), polybutylene terephthalate (PBT), polypropylene (PP) and ethylene -A mixture with a methyl methacrylate copolymer (EMMA) is more preferable.

  The cushion layer may further contain a rubber component. Examples of the rubber component include thermoplastic elastomer materials such as styrene-based thermoplastic elastomers such as styrene-butadiene copolymer and styrene-isoprene copolymer, olefin-based thermoplastic elastomers, amide-based elastomers, and polyester-based elastomers, and natural rubber. And rubber materials such as isoprene rubber, chloroprene rubber and silicon rubber.

  For the cushion layer, antioxidants, slip agents, anti-blocking agents, antistatic agents, coloring agents such as dyes and pigments, additives such as stabilizers, impact resistance imparting agents such as fluororesin and silicon rubber, titanium oxide Inorganic fillers such as calcium carbonate and talc may be included.

  In addition, as a method of forming a cushion layer, well-known methods, such as an air cooling or a water cooling inflation extrusion method and a T-die extrusion method, are mentioned, for example.

  The thickness of the cushion layer is preferably 20 μm or more and 100 μm or less, more preferably 40 μm or more and 90 μm or less, and most preferably 50 μm or more and 70 μm or less. When the thickness of the cushion layer is equal to or more than the above lower limit value, it is possible to suppress a decrease in the cushioning property of the release film. When the thickness of the cushion layer is equal to or less than the above upper limit value, it is possible to suppress a decrease in releasability.

  Further, the release film may have a configuration of four or more layers such as four layers and five layers having an adhesive layer, a gas barrier layer, and the like. In this case, the adhesive layer and the gas barrier layer are not particularly limited, and known ones can be used.

<Method for producing release film>
The production method of the release film in this embodiment is different from the conventional production method, and it is necessary to highly control the production conditions of the release layer. That is, for the first time by the manufacturing method that highly controls various factors related to the following two conditions, the value of the peel voltage | Q ₁ | on the release layer surface of the release film measured under specific conditions is the above-described value. A release film satisfying specific conditions can be obtained.
(1) Selection of resin material for forming release layer (2) Conditions and method for annealing treatment

Hereinafter, an example of the manufacturing method of the release film which concerns on this embodiment is demonstrated. However, the manufacturing method of the release film of this embodiment is not limited to the following examples. An example of the method for producing the release film of the present embodiment will be specifically described later in Examples.
First, (1) selection of a resin material for forming a release layer will be described.
When a crystalline polyester resin is selected as the polyester resin forming the release layer, the degree of orientation of the release layer can be controlled. However, the release layer in the present embodiment cannot be realized simply by forming the release layer using a crystalline polyester resin. This is because the crystalline polyester resin has a polar group such as a carboxyl group. Therefore, when a release layer is formed using a crystalline polyester resin, the amount of polar groups such as carboxyl groups in the material forming the surface (release surface) of the release layer is also highly controlled. There is a need. By doing so, when heat-pressing, the interaction between the unreacted functional group in the material forming the surface of the object on which the release film is arranged and the carboxyl group in the resin forming the release layer It is possible to suppress this.

  In addition, a polyester resin obtained by a solid phase polymerization reaction may be used as the polyester resin. The crystallinity of the polyester resin can be controlled by controlling the reaction conditions such as the type of polymerization catalyst, reaction temperature, and reaction time in solid phase polymerization.

  Moreover, you may control the molecular weight of the monomer used when synthesize | combining a polyester resin. By doing so, the orientation of the crystal component in the polymer can be controlled.

  Moreover, you may control the polymerization degree of a polyester resin. By doing so, the balance between the viscosity and elasticity of the release layer itself can be controlled.

Next, (2) annealing treatment conditions and methods will be described.
In order to obtain the release film in the present embodiment, annealing conditions suitable for the resin material for forming the release layer selected as described in (1) above may be adopted. Specifically, it is particularly important to highly control and combine various factors such as processing temperature, processing time, material of the apparatus used for annealing, and surface temperature of the apparatus used for annealing. In order to manufacture the release film in this embodiment, it is desirable to set the annealing treatment conditions such that the treatment temperature is 190 ° C., the treatment time is 5 minutes, and 10 MPa.

  The above conditions (1) and (2) are combined in a highly controlled manner, and the release film is prepared using a known method such as a co-extrusion method, an extrusion lamination method, a dry lamination method, or an inflation method. Can do. In addition, when the release film has a multilayer structure, the release layer and the cushion layer may be manufactured separately and then joined by a laminator or the like, but the air-cooled or water-cooled coextrusion inflation method, coextrusion T It is preferable to form a film by a die method. Among these, a method of forming a film by a coextrusion T-die method is particularly preferable because it is excellent in controlling the thickness of each layer. Further, the release layer and the cushion layer may be joined as they are, or may be joined via an adhesive layer.

<Usage of release film>
Next, the usage method of the release film of this embodiment is demonstrated.
You may use the release film of this embodiment, for example when producing a flexible printed circuit board. In this case, in order to protect the circuit formed on the flexible film, the release film is interposed between the coverlay and the pressing machine when the coverlay film is heated and pressed against the circuit. To use.
Specifically, the release film is used, for example, in a cover lay press laminating process which is one of the manufacturing processes of a flexible printed wiring board. More specifically, the release film is disposed so as to wrap the coverlay film so that the coverlay film adheres to the concavo-convex portion of the circuit pattern when the coverlay film is adhered to the circuit exposed film. At the same time, it is heated and pressurized by a press. At this time, in order to improve cushioning properties, paper, rubber, fluororesin sheet, glass paper, or the like, or a combination of these may be inserted between the release film and the press machine and then heated and pressed. The press raises the temperature from room temperature to 170 ° C. in 15 minutes from the start of pressurization, then maintains the temperature for 35 minutes, and then cools from 170 ° C. to room temperature over 50 minutes. The pressing pressure at this time is appropriately adjusted at 5 to 15 MPa.

Moreover, you may use the release film of this embodiment with the following method.
First, the surface of the release layer of the release film according to the present embodiment is disposed on the surface of an object formed of a material containing a thermosetting resin. And it press-processes in the metal mold | die with respect to the target object which has arrange | positioned the release film. Here, the thermosetting resin described above may be in a semi-cured state or a cured state. However, when the thermosetting resin is in a semi-cured state, the effect of the release film becomes more remarkable. In particular, when the thermosetting resin is a resin composition containing an epoxy resin, the epoxy resin is preferably in an intermediate stage of the curing reaction, that is, in a B-stage state.

  As mentioned above, although embodiment of this invention was described, these are illustrations of this invention and various structures other than the above are also employable.

  Hereinafter, although an example and a comparative example explain the present invention, the present invention is not limited to these.

<Example 1>
Using polybutylene terephthalate resin (PBT) (manufactured by Mitsubishi Engineering Plastics, Novaduran 502), a 30 μm PBT film was formed by extrusion T-die method, and this PBT film was subjected to 190 ° C. using a press molding machine. A release layer made of PBT was obtained by performing press annealing for 5 minutes at a pressure of 10 MPa.
The release layer, and a modified polyethylene (ethylene-methyl methacrylate copolymer (manufactured by Sumitomo Chemical Co., Ltd., WD206)) and the PBT formed into a film of 60 μm by extrusion T-die method (the blending ratio is ethylene-methyl A methacrylate copolymer: PBT = 80: 20) and a second release layer (sub-release layer) made of the PBT are laminated in this order, and then heated and pressed to form three layers. A release film was produced.
The thickness of each layer of the obtained release film was 30 μm for the release layer and the second release layer (sub-release layer), and 60 μm for the cushion layer.

<Example 2>
Using a polymethylpentene resin (TPX) (manufactured by Mitsui Chemicals, Inc., TPX (registered trademark) MX002), a TPX film of 30 μm was formed by an extrusion T-die method, and a press molding machine was formed on this TPX film. In the same manner as in Example 1 except that a release layer made of TPX obtained by performing a press annealing treatment at 190 ° C. and a pressure of 10 MPa for 5 minutes was used as a sub-release layer. A release film was obtained.

<Example 3>
A release film was obtained in the same manner as in Example 1 except that a cushion layer in which a polyethylene terephthalate resin (PET) (manufactured by SK Chemical Co., Ltd., K2012) was formed into a 60 μm film by extrusion T-die method was used. .

<Comparative Example 1>
Using a polymethylpentene resin (TPX) (manufactured by Mitsui Chemicals, Inc., TPX (registered trademark) MX002), a TPX film of 30 μm was formed by an extrusion T-die method, and a press molding machine was formed on this TPX film. In the same manner as in Example 2 except that the release layer made of TPX obtained by performing the press annealing treatment at 190 ° C. and the pressure of 10 MPa for 5 minutes was used as the release layer. A release film was obtained.

  The following evaluation was performed using the release film obtained by the Example and the comparative example. The results are shown in Table 1.

<Evaluation>
・ Peeling voltage amount at a temperature of 25 ° C. and a relative humidity of 30%: Under the conditions of a temperature of 25 ° C. and a relative humidity of 30%, the release layer of another release film on the release layer surface of one release film The surface opposite to the surface having the surface is overlapped and pressed with a load of 1 kg for 0.5 minutes, and then the one release film and the other release film are peeled at a peeling speed of 300 mm / min. The peeling voltage Q ₁ on the surface of the release layer of the one release film immediately after the measurement was measured. For measuring the stripping voltage amount, a stripping charge measuring band voltage measuring device (ELECTRO LOCATOR SS-2, manufactured by SIMCO JAPAN) was used. The unit was V. In addition, the peeling electrification voltage of 0.5 minutes at elapsed after peeling was Q _2.

-10-point average roughness Rz of the release surface: measured according to JIS B0601 (1994) using “Tokyo Seimitsu Co., Ltd. Handy Surf E-35B” for the center n = 3. The surface 10-point average roughness of the release surface of the release layer was defined as the surface Rz, and the surface 10-point average roughness of the release surface of the sub-release layer was defined as the back surface Rz.

-Oxygen permeability: The oxygen permeability of the release film is an attachment in JIS K7126-2 using an oxygen permeability measuring device (Oxytran (registered trademark) OX-TRAN 2/21) manufactured by MOCON. Measured according to Letter B. The measurement conditions were set at 25 ° C. and 65 RH%. The unit is cc / m ² · day.

Oxygen permeability index: Using a press machine, the oxygen permeability was measured before and after 120 seconds of hot pressing with a release film at a pressure of 60 ° C. and a pressure of 60 kg / cm ² . And when the oxygen permeability measured before performing the hot press is OTR ₁ , and the oxygen permeability measured after the press is OTR ₂ , the value calculated by the following formula (1) from the obtained measurement result is The oxygen transmission index was used.
Oxygen transmission index = (OTR ₂ / OTR ₁ ) × 100 (1)

・ Peel strength (Releasability)
The circuit-exposed film with the coverlay film temporarily fixed with an adhesive is wrapped from both sides with the release film so that the release layer faces the surface of the circuit-exposed film coverlay film. The press was hot-pressed for 2 minutes at 195 ° C. and a pressure of 6 MPa. Immediately thereafter, using a tensile tester, stress was applied in the direction of 180 ° at a speed of about 50 mm / second to release the release films on both sides. At this time, if the release film can be easily peeled off at the time of release, it is determined as A because the release property is good, and if the release film is caught on the circuit exposed film at the time of release, the release property is insufficient. Judgment was made.

・ Follow-up property A polyimide surface of CL (CM type) manufactured by Arisawa Manufacturing Co., Ltd. was bonded to the release surface of the release film, and heat pressing was performed for 2 minutes at a pressure of 195 ° C. and 6 MPa using a press molding machine. After that, the release film was peeled off by applying a stress at a speed of about 50 mm / second in a 180 ° direction using a tensile tester, and the surface of CL was subjected to a “7.5.7.2 wrinkle” of the JPCA standard. It measured according to.
○: Wrinkle occurrence rate less than 2.0% ×: Wrinkle occurrence rate 2.0% or more

・ Non-contaminating After the release film and the circuit exposure film are stacked, paper is inserted between the release film and the press machine, and after 2 hours of heat press at 195 ° C. and 6 MPa, the circuit is exposed. The copper circuit portion of the film was plated and the rate of occurrence of plating and burr defects was measured.
○: Defect occurrence rate less than 10% ×: Defect occurrence rate 10% or more

  The release films of Examples 1 to 3 had excellent wrinkle resistance and non-contamination properties in addition to the balance between the release properties and the followability, whereas the release films of the comparative examples. Was insufficient in terms of non-contamination.

Claims (8)

A release film having a release layer containing a polyester resin material on at least one surface,
The surface opposite to the surface having the release layer of the other release film was superposed on the release layer surface of one release film, and pressurized with a load of 1 kg for 0.5 minutes. Thereafter, the release layer surface of the one release film immediately after the one release film and the other release film are peeled off at a peeling speed of 300 mm / min at a temperature of 25 ° C. when the peeling electrification voltage amount was Q ₁ in,
A release film having | Q ₁ | of 100 v or more and 1000 v or less. The release film according to claim 1,
The surface opposite to the surface having the release layer of the other release film was superposed on the release layer surface of one release film, and pressurized with a load of 1 kg for 0.5 minutes. Thereafter, the one release film and the other release film are peeled off at a peeling speed of 300 mm / min under the condition of a temperature of 25 ° C., and the one release film after 0.5 minutes has passed after peeling. when the charged voltage amount in the release layer surface of the mold film was Q _2,
A release film in which Q ₂ / Q ₁ is 1 or less. The release film according to claim 1 or 2,
A release film in which the release layer contains polybutylene terephthalate. In the release film as described in any one of Claims 1 thru | or 3,
The mold release film whose surface 10 point average roughness Rz of the mold release surface in the said mold release film is 0.1 micrometer or more and 20 micrometers or less. In the release film as described in any one of Claims 1 thru | or 4,
When the oxygen transmission rate of the release film at 25 ° C. and 65 RH% is OTR ₁ and the thickness of the release film is T, the value of OTR ₁ / T is 5 × 10 ² cc / m ³ · day or more. A release film that is 9 × 10 ⁵ cc / m ³ · day or less. The release film according to claim 5,
A release film in which the value of the oxygen permeability OTR ₁ of the release film at 25 ° C. and 65 RH% is ₁ cc / m ² · day to 100 cc / m ² · day. In the release film as described in any one of Claims 1 thru | or 6,
A release film having a three-layer structure in which the release layer, the cushion layer, and the sub-release layer are laminated in this order. The release film according to claim 7,
A release film in which the cushion layer contains a mixture of an α-olefin-based polymer and an α-olefin- (meth) acrylic acid ester copolymer.