JP6391554B2 - Release film - Google Patents

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 the conventional release film, in order to improve the followability of the release film, the crystallinity of the resin material constituting the release layer may be set low. However, in this case, since the rigidity of the release film is reduced, the resin can penetrate into the gap with the circuit, but the release film cannot be sufficiently contracted due to the thermal history applied during use. As a result, the releasability tended to decrease.
On the other hand, in order to improve the release property of the release film, when the crystallinity of the resin material constituting the release layer is set high, the rigidity of the release film is increased, so that there is a gap between the release film and the circuit. It may be difficult to make the resin follow sufficiently. Thus, this inventor discovered that there existed a trade-off relationship between mold release property and followability in the conventional mold release film.

  Then, this invention provides the release film which improved the balance of mold release property and followable | trackability.

  As a result of intensive studies to achieve the above-mentioned problems, the inventors have determined that the ratio of the total light transmittance per 1 μm thickness of the film before and after applying the thermal history to the release film is The present invention has been completed by finding that it is effective as a design guideline for improving the balance between moldability and followability.

According to the present invention, a release film having a release layer containing a polyester resin material on at least one surface,
Having a cushion layer on the release layer;
Before performing the heat treatment at 180 ° C. for 120 seconds on the release film, T1 is the total light transmittance per 1 μm thickness of the release film measured according to JIS-K-7361 under the condition of 23 ° C. ,
After performing the heat treatment at 180 ° C. for 120 seconds on the release film, the total light transmittance per 1 μm thickness of the release film measured according to JIS-K-7361 under the condition of 23 ° C. is T2. When
The value of T2 / T1 is, Ri 0.99 less than Der more than 0.8,
After the heat treatment at 180 ° C. for 120 seconds on the release film, the storage elastic modulus of the release film at 100 ° C. measured at a frequency of 1 Hz is 0.1 GPa or more and 5 GPa or less,
The release layer comprises polybutylene terephthalate;
There is provided a release film in which the cushion layer contains a mixture of an α-olefin polymer and an α-olefin- (meth) acrylate copolymer and does not contain polybutylene terephthalate .

  ADVANTAGE OF THE INVENTION According to this invention, the release film which improved the balance of mold release property and followable | trackability can be provided.

<Release film>
The release film in this embodiment has a release layer containing a polyester resin material on at least one surface. And the mold release film in this embodiment is per 1 μm in thickness of the film measured according to JIS-K-7361 under the condition of 23 ° C. before performing heat treatment at 180 ° C. for 120 seconds. The total light transmittance was T1, and the film was subjected to heat treatment at 180 ° C. for 120 seconds, and then measured according to JIS-K-7361 under the condition of 23 ° C. The total light transmittance per 1 μm thickness of the film. When the rate is T2, the value of T2 / T1 is 0.8 or more and less than 0.99. Thereby, the balance of the mold release property and followable | trackability of a release film can be improved.

  In the release film according to the present embodiment, the release layer forms at least a surface (hereinafter, also referred to as “release surface”) that contacts the object when the release film is disposed on the object. The polyester resin is a polycondensate of polyvalent carboxylic acid (dicarboxylic acid) and polyalcohol (diol), and is a compound having a plurality of carboxyl groups (—COOH).

In order to produce a molded product, the release film is generally used by being disposed on the surface of an object formed of a material containing a thermosetting resin. Specifically, the release film is used by being placed on the surface of an object installed in a mold of a press molding machine. Moreover, in order to manufacture a molded article, the press process in the state which has arrange | positioned the release film on the target object surface is required. Usually, when performing the press treatment described above, a heat history is added to the release film.
Here, as a thermosetting resin contained in the material which forms the surface of a target object, the resin composition containing an epoxy resin is mentioned, for example. In the present embodiment, a surface that contacts the surface of the object when placed on the surface of the object in the release film is referred to as a mold release surface.

  The present inventor has found that the following inconvenience occurs when a conventional release film is used. First, in the case of a conventional release film, when the crystallinity of the release layer is set low in order to increase the followability of the film, the resin can penetrate into the gap between the circuit and the heating. In some cases, the release film could not be sufficiently shrunk due to the heat history applied during pressing. Second, in the conventional release film, when the crystallinity of the release layer is set high in order to improve the film peelability, it becomes difficult to sufficiently follow the resin in the gap with the circuit. was there.

As described above, the release film according to this embodiment controls the value of the ratio T2 / T1 of the total light transmittance per 1 μm thickness of the film before and after applying a thermal history to the release film. It is. In this way, a release film having good characteristics both in terms of ease of peeling from the object after using the release film and in terms of unevenness followability to the surface of the object, can do. The reason for this is not clear, but it is considered that the crystallinity of the resin material constituting the release layer according to the present embodiment is sufficiently improved by hot pressing. In general, it is said that the resin material constituting the release layer is improved in crystallinity and whitening by applying a thermal history. The release film according to the present embodiment utilizes this phenomenon, and is designed so that the variation in crystallinity before and after the hot press becomes large.
In addition, generally the value of the total light transmittance of a release film is not influenced by the surface shape of a release layer.

  Here, in the release film according to the present embodiment, the thickness of the film before and after performing heat treatment at 180 ° C. for 120 seconds on the release film, that is, before and after applying a thermal history to the release film. The value of the ratio T2 / T1 of the total light transmittance per 1 μm is 0.8 or more and less than 0.99, preferably 0.82 or more and 0.98 or less, more preferably 0.85 or more. 0.97 or less. By doing so, the releasability and followability can be improved in a well-balanced manner, and when the release film is peeled off from the object after the heating press, no contaminants remain on the surface, and the shape of the surface However, it becomes possible to obtain a smooth molded article of good quality.

  Moreover, in the release film according to the present embodiment, the thickness of the release film measured according to JIS-K-7361 under the condition of 23 ° C. before the film is heated at 180 ° C. for 120 seconds. The value of the total light transmittance per 1 μm is preferably 55% or more and 95% or less, and more preferably 58% or more and 92% or less. By carrying out like this, when using a release film (when arrange | positioning on the target object surface), it is possible to obtain favorable followability to such an extent that a part of the said release film does not wave.

  Moreover, in the release film which concerns on this embodiment, after performing the heat processing for 120 second at 180 degreeC to the said film, the thickness of the said film measured according to JIS-K-7361 on the conditions of 23 degreeC The total light transmittance value is preferably 50% or more and 92% or less, and more preferably 55% or more and 90% or less. By carrying out like this, it is possible to obtain a good release property after using the release film (after hot pressing).

  In addition, the release film according to this embodiment has a storage elastic modulus of 100 ° C. when the release film is measured at a frequency of 1 Hz after the release film is heated at 180 ° C. for 120 seconds. It is 05 GPa or more and 10 GPa or less, More preferably, it is 0.1 GPa or more and 5 GPa or less. By carrying out like this, it is possible to improve the peelability from the unevenness | corrugation of the said film after use (after a heat press) of a release film. That is, by controlling so that the storage elastic modulus value after applying the thermal history is within the above numerical range, the change in the crystallinity of the release layer before and after the use of the release film (before and after heating press) As a result, it is possible to improve the balance between releasability and followability.

  The surface 10-point average roughness (Rz) of the release surface of the release layer is preferably 0.5 μm or more from the viewpoint of obtaining stable release properties while ensuring the strength of the release layer. Is 1.0 μm or more, and most preferably 1.5 μm or more. On the other hand, from the viewpoint of suppressing the surface roughness from being transferred to the surface of the object, the surface 10-point average roughness (Rz) of the release surface of the release layer is preferably 10 μm or less, More preferably, it is 8 μm or less, and most preferably 7 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 applied to a surface (release surface) on 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 surface roughness from being transferred to the surface of the object, the average interval (Sm) of the irregularities is preferably 450 μm or less, and 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 concerning the surface (release surface) which hits a target object 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 surface roughness from being transferred to the surface of the object, 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. In addition, the arithmetic average roughness (Ra) according to the present embodiment refers to a numerical value applied to 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 30 N / 50 mm or less, and more preferably 25 N / 50 mm or less. The peel strength can be measured, for example, by the following method. First, the adhesive surface of the coverlay film is bonded to the release surface of the release film, and a test piece is prepared by performing hot pressing for 2 minutes at 195 ° C. and a pressure of 6 MPa. Thereafter, a tensile test is performed on the obtained test piece by applying a stress in the 180 ° direction at a speed of about 50 mm / second using a tensile tester. By doing so, the peel strength between the release surface of the release film and the adhesive surface of the coverlay film can be measured. The measurement of peel strength is preferably carried out immediately after hot pressing.

  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.

  Other components copolymerized in the polyester copolymer resin copolymerized with other components include known acid components, alcohol components, phenol components, derivatives thereof having ester forming ability, polyalkylene glycol components, and the like. It is done.

  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. 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. 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 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 (at the time of heating press), heat and pressure from the press hot plate are easily transmitted to the adherend, and the adhesion and follow-up between the release film and the adherend are facilitated. The property can be further improved.

  Examples of the resin material for forming the cushion layer include α-olefin polymers such as polyethylene and polypropylene, α-olefin copolymers having a polymer component of ethylene, propylene, butene, pentene, hexene, methylpentene, and the like. Engineering plastics resins such as ether sulfone 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 30 μm or more and 100 μm or less, more preferably 50 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 a manufacturing method that is highly controlled by appropriately combining various factors related to the following three conditions before and after applying a thermal history (before and after heat treatment at 180 ° C. for 120 seconds) per 1 μm of film thickness A release film in which the value of the total light transmittance ratio T2 / T1 satisfies the above-described specific conditions can be obtained.
(1) Selection of resin material for forming release layer (2) Conditions for annealing treatment / method (3) Cooling conditions for film formation

Hereinafter, an example of the manufacturing method of the release film which concerns on this embodiment is demonstrated.
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 this, 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 placed and the polar group in the resin forming the release layer It is possible to suppress this for the first time. On the other hand, when the release layer is formed using an amorphous polyester resin, it is important to appropriately control various factors according to (2) and (3) described later appropriately.

  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, it is necessary to employ annealing conditions suitable for the resin material for forming the release layer selected as described in (1) above. Specifically, the necessity of annealing treatment is selected according to the type of resin material forming the release layer, and when annealing treatment is performed, the treatment temperature, the treatment time, the apparatus used for the treatment, It is particularly important to combine the respective factors such as the material and the surface temperature of the apparatus used for the treatment in a highly controlled manner. Examples of the annealing treatment method include a method using a hot air dryer without applying pressure and a method of applying pressure and heating. Moreover, when performing an annealing process using the said hot air dryer, it is necessary to control a heating condition in order to control the crystallization state of the mold release layer which is a surface layer. If the above conditions are not controlled, it is considered that heat transmission takes time, and as a result, the entire film is heated. On the other hand, in the case of adopting the above pressure heating method, it is important to control the conditions in order to suppress fluctuations in the surface shape and thickness of the film.

Next, (3) the cooling conditions during film formation will be described.
In order to obtain the release film in the present embodiment, it is necessary to adopt cooling conditions during film formation suitable for the resin material for forming the release layer selected as described in (1) above. . Specifically, whether or not to perform the cooling process during film formation is selected according to the type of the resin material forming the release layer, and when the cooling process is performed, the cooling process method, cooling It is particularly important to highly control and combine factors such as the temperature setting of the apparatus used for processing and the cooling processing speed. By doing so, it becomes possible to prevent the resin material constituting the release layer and the sub-release layer from being excessively crystallized, and as a result, the storage elastic modulus is lowered with respect to the release film itself. Can also be suppressed.
Usually, the said release film formed into a film by the method mentioned later is wound up, after making it press-fit to the cooled metal roll. Adjusting the crystallization state of the resin material that constitutes the release layer and the sub-release layer by highly controlling the conditions (corresponding to the cooling conditions described above) at the time of pressure bonding to the cooled metal roll. Is possible.
And as a cooling processing method mentioned above, the method of crimping | bonding to the metal roll cooled using the touch roll or the air knife is mentioned. In addition, the temperature setting of the apparatus used for the above-described cooling treatment may be a temperature of 10 ° C. or more and 50 ° C. or less when any of a touch roll, an air knife, and a metal roll is used. Furthermore, the cooling treatment speed described above may be set to 50 ° C./s or more and 60 ° C./s or less from the viewpoint of suppressing excessive crystallization of the resin material constituting the release layer or the sub release layer. Good.

  On the premise that the various factors according to the above conditions (1) to (3) are appropriately combined and controlled to a high degree, the release film is formed by coextrusion method, extrusion lamination method, dry lamination method, inflation method. It can manufacture using well-known methods. 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.
First, the surface of the release layer of the release film according to the present embodiment is disposed on the surface of the molded product 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.

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 heated between the cover lay film and the press molding machine when the cover lay film is heated and pressed against the circuit. Use with interposition.
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 molding machine. The press molding machine raises the temperature from room temperature to 170 ° C. in 15 minutes after the start of pressurization, 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.

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, examples of the reference form will be added.
<1> A release film having a release layer containing a polyester resin material on at least one surface,
Before performing the heat treatment at 180 ° C. for 120 seconds on the release film, T1 is the total light transmittance per 1 μm thickness of the release film measured according to JIS-K-7361 under the condition of 23 ° C. ,
After performing the heat treatment at 180 ° C. for 120 seconds on the release film, the total light transmittance per 1 μm thickness of the release film measured according to JIS-K-7361 under the condition of 23 ° C. is T2. When
A release film having a value of T2 / T1 of 0.8 or more and less than 0.99.
<2> After the heat treatment of the release film at 180 ° C. for 120 seconds, the storage elastic modulus of the release film at 100 ° C. measured at a frequency of 1 Hz is 0.05 GPa or more and 10 GPa or less. 1>. A release film according to 1>.
<3> The release film according to <1> or <2>, wherein the release layer includes polybutylene terephthalate.
<4> The release film according to any one of <1> to <3>, which has a three-layer structure in which the release layer, the cushion layer, and the sub-release layer are stacked in this order.
<5> The release film according to <4>, wherein the cushion layer includes a mixture of an α-olefin polymer and an α-olefin- (meth) acrylate copolymer.

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

<Example 1>
Polybutylene terephthalate resin (PBT) (manufactured by Mitsubishi Engineering Plastics, Novaduran 5505S) is used as a material for forming the release layer and sub-release layer, and modified polyethylene (ethylene-methyl methacrylate copolymer) is used as the material for forming the cushion layer. A polymer (Sumitomo Chemical Co., Ltd., WD203-1)) and a metallocene low-density polyethylene (EPPE, manufactured by Sumitomo Chemical Co., Ltd., Excelen CB5002) containing no antioxidant were used. The blending ratio of the material forming the cushion layer was ethylene-methyl methacrylate copolymer: EPPE = 80: 20.
A laminated film composed of three layers was formed by an extrusion T-die method so that the release layer, the cushion layer, and the sub-release layer were laminated in this order. Subsequently, the release film which consists of three layers was manufactured by pressing the surface by the side of the release layer in the obtained laminated | multilayer film with the metal roll cooled at 30 degreeC with the air knife. The temperature of the air blown from the air knife was 25 ° C.
The thickness of each layer of the obtained release film was 25 μm for both the release layer and the sub-release layer, and 70 μm for the cushion layer.

<Example 2>
A release film was obtained in the same manner as in Example 1 except that the release layer and the sub-release layer were formed to have a thickness of 30 μm and the cushion layer had a thickness of 140 μm.

<Example 3>
PBT (Toray Industries, Inc., 1201K) was used as a material for forming the release layer and sub-molding layer, PBT (Toray Industries, 1201K) as a material for forming the cushion layer, and glycol-modified polyethylene terephthalate (PETG) SK Chemical Co., Ltd., S2008) was used at a blending ratio of PBT: PETG = 80: 20, and surface transfer processing (subject to surface of sub-release layer using 10 ° C. touch roll instead of air knife) A release film in the same manner as in Example 1 except that the film was formed so that the thickness of the release layer and the sub-release layer was 25 μm and the thickness of the cushion layer was 50 μm. Got.

<Example 4>
PBT (Toray Industries, Inc., 1201K) was used as a material for forming the release layer and sub-molding layer, PBT (Toray Industries, 1201K) as a material for forming the cushion layer, and glycol-modified polyethylene terephthalate (PETG) A release film was obtained in the same manner as in Example 1 except that S2008 manufactured by SK Chemical Co., Ltd. was used at a blending ratio of PBT: PETG = 80: 20.

<Example 5>
As materials for forming the cushion layer, PBT (manufactured by Toray Industries, Inc., 1201K), glycol-modified polyethylene terephthalate (manufactured by PETG SK Chemical Co., S2008), and propylene-ethylene copolymer (manufactured by Sumitomo Chemical Co., Ltd., Nobrene FH3315), A release film was obtained in the same manner as in Example 3 except that PBT: PETG: propylene-ethylene copolymer = 10: 80: 10.

<Comparative Example 1>
The use of PBT (manufactured by Mitsubishi Engineering Plastics, Novaduran 5510) as a material for forming a release layer and a sub-release layer, and a propylene-ethylene copolymer (manufactured by Sumitomo Chemical Co., Ltd., Nobrene) as a material for forming a cushion layer A release film was obtained in the same manner as in Example 5 except that FH3315) was used.

<Comparative Example 2>
A release film was obtained in the same manner as in Comparative Example 1 except that modified polyethylene (ethylene-methyl methacrylate copolymer (manufactured by Sumitomo Chemical Co., Ltd., WH102)) was used as a material for forming the cushion layer.

<Comparative Example 3>
A release film was obtained in the same manner as in Comparative Example 1 except that PBT (manufactured by Mitsubishi Engineering Plastics, Nova Duran 5505S) was used as a material for forming the release layer and the sub-release layer.

  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>
-Total light transmittance before heat treatment: The total light transmittance of the release film was measured according to JIS-K-7361 under the condition of 23 ° C. Next, the value of the total light transmittance T1 per 1 μm thickness of the film was calculated by dividing the obtained measurement result by the thickness of the film. The unit is%.

-Total light transmittance after heat treatment: First, the obtained release film was subjected to heat treatment under conditions of 180 ° C for 120 seconds. About the release film after this heat processing, the total light transmittance was measured according to JIS-K-7361 on the conditions of 23 degreeC. Next, the value of the total light transmittance T2 per 1 μm thickness of the film was calculated by dividing the obtained measurement result by the thickness of the film. The unit is%.

Storage modulus at 100 ° C. after heat treatment: First, the obtained release film was subjected to heat treatment at 180 ° C. for 120 seconds. About the release film after this heat processing, the storage elastic modulus in 100 degreeC, the frequency of 1 Hz, and the temperature increase rate of 10 degree-C / min was measured using the dynamic viscoelasticity apparatus. The unit is GPa.

-According to JIS B0601 (1994), according to JIS B0601 (1994), the surface of the release surface of the release layer and the release surface of the sub-release layer is “Handy Surf E-35B manufactured by Tokyo Seimitsu”. , Measured for center n = 3. The unit is μm.

・ Releasability: Adhesive surface of CL (CM type) manufactured by Arisawa Manufacturing Co., Ltd. was pasted on the release surface of the release film, and heat-pressed at 195 ° C x 2 minutes x 6 MPa, and a tensile tester (A & D) Using a force gauge AD-4932A-50N), the peel force between the release surface and the CL adhesive was measured at a speed of about 1000 mm / min in the 180 ° direction. The measurement was performed immediately after pressing, and the releasability was evaluated based on the following criteria.
○: Peelable △: Peelable to the extent that there is no problem in practical use, but peeling slightly heavy ×: Peeling is heavy and film or CL breaks

・ Followability (finished appearance wrinkle): Measured according to “7.5.7.2 Wrinkle” of the JPCA standard.
○: Wrinkle occurrence rate less than 1.5% △: Wrinkle occurrence rate 1.5% or more and less than 2.0% ×: Wrinkle occurrence rate 2.0% or more

・ Plating properties (those with 90% or more of the required plating area are plated: non-defective product: depending on the appearance of 7.5.4 plating)
○: 98% or more of good products △: 95% or more and less than 98% of good products ×: Less than 95% of good products

  The release films of the examples were all excellent in the balance between the release properties and the followability, whereas the release films of the comparative examples were unsatisfactory in terms of the balance between the release properties and the followability. It was enough.

Claims (2)

A release film having a release layer containing a polyester resin material on at least one surface,
Having a cushion layer on the release layer;
Before performing the heat treatment at 180 ° C. for 120 seconds on the release film, T1 is the total light transmittance per 1 μm thickness of the release film measured according to JIS-K-7361 under the condition of 23 ° C. ,
After performing the heat treatment at 180 ° C. for 120 seconds on the release film, the total light transmittance per 1 μm thickness of the release film measured according to JIS-K-7361 under the condition of 23 ° C. is T2. When
The value of T2 / T1 is, Ri 0.99 less than Der more than 0.8,
After the heat treatment at 180 ° C. for 120 seconds on the release film, the storage elastic modulus of the release film at 100 ° C. measured at a frequency of 1 Hz is 0.1 GPa or more and 5 GPa or less,
The release layer comprises polybutylene terephthalate;
A release film in which the cushion layer contains a mixture of an α-olefin polymer and an α-olefin- (meth) acrylate copolymer and does not contain polybutylene terephthalate . The release layer has a cushion layer, and a three-layer structure of the order of FukuHanare type layer, release film of claim 1.