JP2001225418A - Release film and protective film for prepreg using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a release film having both of high-degree dimensional stability and adhesion and a protective film for a prepreg. SOLUTION: The release film is constituted by forming a release layer consisting of 15-85 weight % of a cellulosic resin and 85-15 weight % of a curable resin on one surface of a polyester film. The absolute value of the dimensional change ratio of this release film at a time when the release film is heated and cooled within a temperature range from ordinary temperature to 170 deg.C under a stress of 0.785 MPa satisfies the formula: (lc-lh)/lh<=0.006 (wherein lc is a dimension at 30 deg.C at a time of cooling and lh is a dimension at 30 deg.C at a time of heating) in the molding direction of the polyester film and the lateral direction vertical thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a release film, and more particularly to a release film in which a release layer contains a fibrous resin and has improved thermal dimensional stability and adhesion.

[0002]

2. Description of the Related Art Release films have been used as carrier films for molding such as pressure-sensitive adhesive films, resin sheets, resin films or ceramic green sheets, or as carrier films for protection such as prepreg. For example, a vinyl chloride resin sheet used as a marking sheet is obtained by applying a solution obtained by dissolving a vinyl chloride resin in a solvent onto a release film (carrier film) and then removing the solvent by heating. The release film used for the above is called a carrier film for molding. Also,
An insulating resin sheet (prepreg) for a circuit board is formed by impregnating glass, paper or thermoplastic fiber fabric with a thermosetting resin, evaporating a solvent or the like, and, at the same time, exhibiting a solid property at room temperature (B stage). ), By heat and pressure bonding with a metal foil to be a circuit to obtain a completely cured state (C stage). At this time, a release film is attached to the surface of the prepreg to prevent foreign substances from adhering to the surface of the prepreg in the semi-cured state (B stage) and to prevent a blocking phenomenon from occurring with other prepregs. Can be The release film used for the purpose of protecting the surface of the product is called a protective film.

Incidentally, it is necessary that such a release film does not cause a dimensional change when being bonded. This is because if the dimensional change occurs while the release film is bonded, wrinkles or sagging will occur in the release film, and the release film will peel off or foreign substances enter from that part, or the wrinkles will occur. This is because irregularities such as slack are transferred to the protective surface. In particular, this dimensional stability is strongly demanded for a prepreg protective film that is subjected to a high degree of heat treatment such as laser drilling while a release film is bonded.

[0004] Means for improving dimensional stability include, for example,
Heat-cured on at least one side of the polyester film
Containing 70% by weight or more of photo-curable resin or photo-curable resin
The oil layer is formed in a thickness of 3 to 20 based on the thickness of the obtained film.
% And when the resin layer is cured
Film tension on the release film of 400g / mm
^TwoThe heat shrinkage rate at 140 ° C for 5 minutes
0.13% to 0.18% in film length direction and width direction
-0.06 to -0.11% dimensional stability
That a film can be obtained as disclosed in JP-A-11-277703.
It is proposed in the gazette. Indeed, according to the publication,
Thermosetting resin or photocurable resin with high dimensional stability
The resin layer made of fat is made of a composition and
And harden under low tension.
A heat-resistant film having dimensional stability is obtained.

[0005] However, the present inventors have studied according to the publication and found that when the heat-resistant film disclosed in the publication is used as a release film, a release layer made of curable silicone is formed. When used as a surface protective film, it is easy to peel off during the manufacturing process, and the silicon in the release layer migrates to the prepreg surface, resulting in a fatal problem that the adhesion between the subsequent prepreg and the metal foil becomes insufficient. I found that there were some flaws.

[0006] In recent years, with the reduction in size and weight of electronic devices, particularly mobile communication devices typified by mobile phones and portable personal computers, and portable information terminal devices, electronic components used in those electronic devices, Semiconductor components are also becoming smaller, lighter and more highly integrated. DVC (Digital Video Cassette) for AV (Audio Visual) equipment
Components and semiconductor components used in new recording media such as DVDs and DVDs (Digital Video Disks) have similar requirements. Various on-line inspection devices are used during the manufacturing process of resin sheets and ceramic sheets used as components of electronic components, substrates and semiconductor components used in these electronic devices. (Including release film and protective film), detection of defects such as unevenness of thickness and flatness and pinholes of molded resin sheet, and position in circuit pattern printing, electrode printing, laminating, drilling process, etc. Settings, corrections, etc. are made. Usually, the sensors of these inspection apparatuses use light, in particular, laser light in the visible light region or information obtained from a CCD camera (charge-coupled device camera) to process defects and control the position. These inspection devices are light of a specific wavelength such as laser light, or A light source,
It detects the transmittance and reflectance of light oscillated and emitted by a standard light source such as a C light source or a D65 light source or a fluorescent lamp. To increase the detection sensitivity of these inspection devices, a release film is used for each inspection device. Coloring has been performed in accordance with the light. However, the light of these inspection devices is rarely unified to any one, and a plurality of types of light are used in the same process depending on the purpose. Did not provide good inspection characteristics. Therefore, there has been a strong demand for a release film having good inspection characteristics in all inspection apparatuses.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to improve the drawbacks of the prior art and to achieve a high degree of dimensional stability while having both peel strength and the ability to prevent migration of the agent in the release layer. And a protective film for prepreg using the same. Another object of the present invention is to provide the above-mentioned release film and the protective film for prepreg using the same, further having excellent inspection suitability for an online inspection device using visible light of any wavelength.

[0008]

In order to solve the above-mentioned problems, the present inventors first eliminated the silicone layer which extremely reduces the peel strength from the release film of the above-mentioned publication, and removed the thermosetting resin. It was considered that the main resin layer was adopted as the release layer. As a result of the study by the present inventors, it has been found that it is preferable to have a peel strength of at least 25 mN / 5 cm in order to suppress the peeling of the release film during the manufacturing process of the prepreg. The peel strength of a fully cured thermosetting resin such as
It was at most 15 mN / 5 cm, and elimination of the silicone layer alone was insufficient to suppress the release of the release film. By the way, the peel strength of a thermosetting resin is closely related to its cured state, and by utilizing this property,
Attempts were also made to make the cured state of the thermosetting resin incomplete. As a result, the peel strength could be improved, but the unreacted functional groups remain in the release layer, so that the release layer changes with time, and furthermore, the uncured part is protected. There has been a problem that it is firmly bonded to the surface of the product and is cohesively peeled off from the release film. In addition, since the temperature and time of the heat treatment were relaxed to make the release layer insufficiently hardened, it was also found that the thermal dimensional stability of the obtained film was reduced. From these viewpoints, it can be said that the improvement of the peel strength, the prevention of the transfer of the release agent, and the thermal dimensional stability have a trade-off relationship of 2%.

Therefore, the present inventors consider that it is impossible to achieve both improvement in peel strength, prevention of transfer of the release agent, and thermal dimensional stability simply by using a thermosetting resin for the release layer. The research was again attempted from the composition of the resin constituting the shape layer. As a result, it has been found that when a fibrous resin is blended with the curable resin, a high degree of peel strength can be imparted without causing the cohesive peeling of the curable resin constituting the release layer and a decrease in thermal dimensional stability. The present invention has been reached.

Thus, according to the present invention, a release layer comprising a fibrous resin and a curable resin and containing 15 to 85% by weight of the former and 85 to 15% by weight of the latter is formed on one side of the polyester film. The absolute value of the dimensional change rate when heated and cooled in the range from room temperature to 170 ° C. under a stress of 0.785 MPa in the release direction formed in the polyester film in the forming direction of the polyester film and the width direction perpendicular thereto. ,
The following equations respectively

[0011]

(Equation 2)

[0012] Using a release film and which is characterized in that (the l _c in the above formula dimension at 30 ° C. at the time of cooling, and l _h is the. Showing the dimensions at 30 ° C. at the time of heating) satisfies A protective film for a prepreg is provided.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The release film of the present invention comprises a fibrous resin and a curable resin, the release layer containing 15 to 85% by weight of the former and 85 to 15% by weight of the latter. And a polyester film having a release layer on one side. The absolute value of the dimensional change rate when the release film is heated and cooled in a range of from room temperature to 170 ° C. under a stress of 0.785 MPa is determined in accordance with the forming direction (MD direction) of the polyester film and the width direction perpendicular thereto. (TD direction)
It is necessary to satisfy the following equations.

(Equation 3) Here, the absolute value of the dimensional change rate means a thermal stress / strain measuring device (TMA / SS12 manufactured by Seiko Denshi Co., Ltd.).
0C), a sample to which a constant tension is applied is inserted into the heating furnace of the apparatus, and the heating furnace is heated from room temperature. When the sample temperature reaches 170 ° C., the heating furnace is cooled to room temperature. , dimensions of sample temperature 30 ° C. at the time of heating (l _h) and to measure the dimension (l _c) in the sample temperature 30 ° C. during cooling, the values obtained by dividing the dimensional difference obtained by subtracting the former from the latter in the former dimensions It is an absolute value.

The present invention will be described in detail below in the order of a base polyester film, a cellulose resin, a thermosetting resin and a release layer. [Polyester Film] As the polyester film constituting the release film of the present invention, it is preferable to use a polyester film having good transparency, and a biaxially oriented transparent polyester film is particularly preferable. The polyester constituting such a polyester film is a crystalline linear saturated polyester composed of an aromatic dibasic acid component and a diol component, for example, polyethylene terephthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene-2,6- Preferred are naphthalate and the like. Of these, polyethylene terephthalate and polyethylene-2,6-naphthalate are particularly preferred from the viewpoint of processability. It is preferable to mix inorganic fine particles and organic fine particles as a lubricant with such a polyester as necessary. As the lubricant, inorganic fine particles are preferable, and silicon oxide fine particles are particularly preferable.
The polyester may be mixed with an improver other than a lubricant. For example, sodium dodecylbenzenesulfonate or the like can be contained as an antistatic agent.

The polyester film in the present invention comprises:
It can be manufactured by a conventionally known manufacturing method. For example, a biaxially stretched polyester film is obtained by drying a polyester as a raw material, melting it with an extruder, extruding it from a die (for example, a T-die, an I-die, etc.) onto a rotary cooling drum, quenching the unstretched film. Then, the unstretched film is stretched in the machine direction and the transverse direction, and heat-fixed if necessary. Further, in the present invention, from the viewpoint of suppressing a dimensional change with respect to the thermal stress of the polyester film itself, it is particularly preferable to perform a heat relaxation treatment in which the polyester film is relaxed in a longitudinal direction while being heated under low tension after the heat fixing treatment. . As a specific heat relaxation treatment, the biaxially stretched polyester film is shrunk by 1 to 10% in the width direction of the film, and the tension in the film advancing direction is maintained at 14.7 to 98 N / cm ^2. , A heat treatment at a temperature of 120 to 160 ° C. for 5 to 120 seconds. The thickness of the polyester film is preferably from 5 to 250 μm.

[Cellulosic resin] The cellulosic resin referred to in the present invention includes a cellulose resin, for example, an inorganic or organic acid such as cellulose nitrate, cellulose acetate, cellulose sulfate or cellulose sodium xanthate. , Cellulose ester, methylcellulose,
Examples include ethyl cellulose, carboxymethyl cellulose, cellulose acetyl butyrate, cellulose acetyl propionate, hydroxyethyl cellulose, and cellulose ether. Among these,
Cellulose acetyl butyrate, cellulose acetyl propionate, and cellulose nitrate are particularly preferable because of high compatibility with the organic solvent used for dissolving the thermosetting resin.

[Curable resin] The curable resin used in the present invention is not particularly limited as long as it is a resin that can be cured by heat, light such as ultraviolet rays, or an electron beam. Epoxy resin, phenol resin, melamine resin, polyurethane At least one thermosetting resin selected from the group consisting of a resin, a polyimide resin and an acrylic resin is preferable because heat treatment at the time of forming the release layer is effective in improving thermal dimensional stability. Of course, a resin that can be cured by heat other than heat, such as an acrylic photocurable resin, may be used, but in this case, in addition to curing by irradiation with ultraviolet light, it is necessary to separately perform a heat treatment similar to the thermosetting resin. There is.

[Release layer] The most important feature of the present invention is that the release layer is composed of a fibrous resin and a curable resin. The former is 15 to 85% by weight, and the latter is 85 to 1% by weight.
5 wt%, preferably 25-75 wt% and the latter 7
5 to 25% by weight, particularly preferably 30 to 70% by weight, and the latter in an amount of 70 to 30% by weight. When the proportion of the fibrous resin is less than 15% or the proportion of the curable resin exceeds 85%, it takes time to cure the curable resin, or an uncured material is apt to remain, and In the case of a completely cured state, the peel strength becomes insufficient. On the other hand, if the proportion of the fibrous resin exceeds 85% by weight or the proportion of the curable resin is less than 15%, the peel strength becomes excessively strong and does not peel off with a product such as a prepreg at the time of peeling. In addition, the curable resin of the release layer is cohesively peeled off on the surface of the product, and the bonding strength between the base polyester film and the release layer is poor, so that it is easy to peel off the polyester film.

The release layer in the present invention is formed by applying a coating solution containing the above components to one surface of a polyester film, heating and drying. As the coating method, a conventionally known method such as a bar coating method, a doctor blade method, a reverse roll coating method, or a gravure roll coating method can be used. The drying and curing (thermal curing, ultraviolet curing, and the like) of the coating film can be performed by known methods individually or simultaneously. However, in order to ensure the thermal dimensional stability of the obtained release film, as described above, not only the thermosetting resin, but also when using a curable resin other than heat such as light, the coating film is applied. After that, 140-210
° C, preferably 160 to 200 ° C, particularly preferably 17 ° C.
Within a temperature range of 0 to 190 ° C. and 1.0 to 4.0 MP
a, preferably heat treatment in a tension range of 1.2 to 3.0 MPa. By this heat treatment, after heating from room temperature to 170 ° C. under a stress of 0.785 MPa, the absolute value of the dimensional change rate obtained by the above equation when cooled to room temperature is M
It is possible to obtain a release film having extremely high dimensional stability of 0.6% at most in each of the D direction and the TD direction. The absolute value of the dimensional change rate needs to be at most 0.6%, but at most 0.5%, particularly at most 0.4%.
Preferably, the heat treatment temperature ranges from 160 to 200 ° C., particularly 170 to 190 ° C., and the tension ranges from 1.1 to 3.5 MPa, especially from 1.2 to 3.5 MPa.
This can be achieved by setting the pressure to 3.0 MPa. The thickness of the coating film is not particularly limited, but is 0.1 to 10 μm, particularly 0.1 μm.
A range of 5 to 2 μm is preferred.

The release film of the present invention for solving the first problem of the present invention has been described in detail above. Next, the second problem, that is, the release film of the present invention, The colored layer for providing excellent inspection suitability to an online inspection device using visible light of any wavelength will be described in detail below.

[Coloring Layer] In the present invention, it is preferable to provide a coloring layer on the surface of the polyester film opposite to the surface on which the release layer is provided. The coloring layer is formed by applying a coating material in which one or more coloring agents selected from inorganic pigments, organic pigments and dyes are uniformly mixed and dispersed in an organic resin. The coloring agent used for the coloring paint of the present invention is 40
Since it is necessary to uniformly block light of 0 to 800 nm, a black inorganic pigment is most preferable. Examples of such a black inorganic pigment include carbon black and metal oxide.

The carbon black in the present invention is a carbon black having an average particle size of 20 to 100 nm and maintaining a chain structure. Examples of carbon black include acetylene black, Ketjen black, and furnace black depending on the production method. As acetylene black, electrified acetylene black manufactured by Denki Kagaku Kogyo Co., Ltd., and as Ketjen Black, Ketjen Black EC and Ketjen Black E manufactured by Akzo Chemical Co., Ltd.
Examples of C-600DJ and furnace black include Vulcan XC-72 manufactured by Cabot Corporation. These carbon blacks may be used alone or in combination of two or more.

As the metal oxide in the present invention, 4 to
Group 11 metals in the fourth period (Ti, V, Cr, Mn,
Any one selected from Fe, Co, Ni, and Cu)
Oxides of certain metals. These may be used alone, but it is preferable to use a composite oxide containing two or more metals from the above-mentioned metal group in order to function as a light shielding agent for the entire visible light region. The composite oxide is not particularly limited as long as it contains two or more metals. For example, Ni-Cu, Cr-Fe, Fe-Cu,
Cu-Cr, Fe-Co, Fe-Mn, Ti-Mn-C
u, Mn-Fe-Cu, Co-Fe-Cr, Cr-Mn
Oxides containing -Cu and Cr-Cu-Fe are exemplified. The above-mentioned metal oxides and composite metal oxides preferably have an average particle diameter of 1.0 μm or less, and particularly preferably 0.5 μm or less for improving film quality and hue. The shape of the metal oxide particles is not particularly limited,
It may be spherical, scaly or irregular. Also,
The inorganic pigments of the metal oxides and composite metal oxides described above include:
There are pigments other than black, such as yellow, red, blue, green, brown, and gray, but they may be used in combination of two or more kinds so as to shield the entire visible light region of 400 to 900 nm.
Furthermore, two or more kinds of organic pigments and dyes may be similarly mixed to shield the entire visible light region of 400 to 900 nm from light.

As the organic resin constituting the colored layer in the present invention, various organic resins containing at least one selected from a thermoplastic resin, a curable resin and a cellulose resin are used. Examples of the thermoplastic resin include polyester resin, acrylic resin, polyvinyl resin, and phenoxy resin, and examples of the curable resin include curable acrylic resin, melamine resin, epoxy resin, and urethane resin. Include nitrocellulose, acetylcellulose and the like. Among them, the organic resin constituting the colored layer is composed of a fibrous resin and a curable resin because the dimensional change with respect to the thermal stress of the release layer is easily matched with the above-mentioned release layer. 15-85w for the latter
Those containing t% are preferred. The fibrous resin and the curable resin used for the organic resin forming the colored layer are the same as those described for the release layer.

When the coloring layer in the present invention contains a coloring agent, it is formed by applying a coating liquid containing the above-mentioned coloring agent and an organic resin to a polyester film. The coating liquid may be an organic solvent-based or water-based. Further, a dispersant, an anti-settling agent, a cross-linking agent, a curing acceleration catalyst may be added to the coating liquid, and a surfactant may be appropriately added to the aqueous coating liquid in order to prevent repelling of the film. As a method of dispersing the colorant in the coating liquid, any method can be adopted, for example, a method using a combination of a ball mill, a roll mill, a stone mill or a high-speed grinder, or the colorant is already dispersed in a solvent and a dispersant. And a method of mixing the organic resin with the organic resin binder. The amount of the colorant of the present invention varies depending on the type of the colorant, the dispersion method, and the type of the organic resin, but is preferably 1 to 50% by weight, and more preferably 3 to 30% by weight.
% By weight is particularly preferred. The coloring layer can be formed by the same method as that for the release layer.

The colored layer formed by the above method has a total light transmittance of the release film of the present invention of 25 to 75%, especially 35 to 75%.
It is preferable to provide the transmittance in a wavelength range of from about 65% to 400% and a wavelength range of 400 to 900 nm of ± 5%. If the total light transmittance exceeds 75%, the detection device recognizes that there is no film and cannot identify it. If the total light transmittance is less than 25%, the transmitted light is detected for the device that detects transmitted light. become unable. Also, 40
The amplitude of the transmittance in the wavelength range of 0 to 900 nm is 5
% Or more, in particular, only blocking light of a specific wavelength, when using multiple detectors for multiple purposes, for example, EPC, defect inspection or print pattern identification, use different light sources. In such a case, the detection cannot be performed by a certain detection device. In addition, in the drying or curing step of the colored layer, it is preferable to perform the same heat treatment as that of the release layer because the dimensional change due to the thermal stress of the obtained release film is easily suppressed similarly to the release layer.

[0027]

The present invention will be described below in detail with reference to examples. The physical property values and characteristic values in the present invention were measured by the following methods. (1) Dimensional change rate A rectangular film having a width of 4 mm is prepared as a sample,
This was measured with a thermal stress / strain measurement device (Seiko Electronics Co., Ltd.
The distance between chucks is 15 for the jig of TMA / SS120C)
mm, and inserted into the heating furnace of the apparatus. Then, while applying a constant tension of 0.785 MPa to the sample, the temperature of the heating furnace was increased from room temperature to 200 ° C. at a rate of 200 ° C./min.
Hold the furnace temperature until the temperature reaches
When the temperature reaches 0 ° C., the heating furnace is cooled to room temperature at a cooling rate of 200 ° C./min. At this time, to measure the dimensions of the sample with the sample temperature is 30 ° C. during the temperature elevation process (l _h), the dimensions of the sample when the sample temperature in the cooling process of 30 ° C. and (l _c), the former from the latter The dimension obtained by subtracting the above is divided by the former dimension is defined as the dimensional change rate. Therefore, the dimensional change rate is indicated by a negative value when contracted by heating, and a positive value when expanded by heating. In addition, this measurement was performed with respect to the polyester film forming direction (MD direction) and the width direction (TD direction) of the polyester film perpendicular to the MD direction, respectively.

(2) Peeling Strength An untreated polyester film is superimposed on one surface of a glass epoxy prepreg (Sumilite ELC-4756, manufactured by Sumitomo Bakelite Co., Ltd.), and the release layer surface of the release film is laminated on the other surface. Pass through a laminator heated to ° C. Then, after the laminate reaches room temperature, 5 cm
After being cut to a width, the peeling force between the release film and the prepreg was measured at a tensile speed of 30 mm / min using a tensile tester.

(3) Total light transmittance Haze meter manufactured by Nippon Seimitsu Kogaku (JIS-K7105,
The total light transmittance was measured using the standard light source A) with the antistatic layer side facing the light source.

(4) Fluctuation of transmittance (fluctuation of light transmittance at each wavelength of 400 to 900 nm) Using a spectrophotometer (UV-3101PC) manufactured by Shimadzu Corporation, transmission spectra of 400 to 900 nm were measured at 1 nm intervals. The transmittance at each wavelength is calculated and divided by the value of the total light transmittance to calculate a transmittance difference at each wavelength. And it evaluated based on the following criteria. ：: The transmittance difference at each wavelength is all in the range of -5 to + 5%. X: There are wavelengths whose transmittance difference is out of the range of -5 to + 5%.

(5) Suitability for detection Standard light beams A and C as light sources and an argon laser (manufactured by Spectra Physics, wavelength: 5) as a laser source
14.5 nm), ruby laser (Apollo, wavelength: 694 nm), YAG laser-excited dye laser (Continuum, variable wavelength range: 420 to 560 nm)
(THG excitation), 550 to 740 nm (SHG excitation), using a total of six light sources or a detector using a transmission source lamp or laser, to perform a defect inspection of a laminate having a resin sheet provided on a release film. As a result, if any of the detectors could be inspected, it was evaluated as ○, and if none of them could be inspected, it was evaluated as ×.

Example 1 In o-chlorophenol,
Polyethylene terephthalate having an intrinsic viscosity of 0.65 measured at a temperature of 25 ° C. is dried at 170 ° C. for 3 hours, melted, extruded through a slit die heated to 290 ° C., cast on a rotating drum and unstretched. A film was obtained. Then, the obtained unstretched film is stretched 3.7 times in the longitudinal direction while being heated to 90 ° C., and then 3.8 times in the transverse direction while being heated to 110 ° C., at 235 ° C. for 5 seconds. Heat treatment (shrinkage of 5% in the width direction) gave a biaxially stretched film having a thickness of 25 μm.

Next, 50 parts of cellulose nitrate (FQRS1 / 8, manufactured by Daicel Chemical Industries, Ltd.) and epoxy resin (Epicoat 1007, manufactured by Yuka Shell Epoxy Co., Ltd.) 2
0 parts and melamine resin (Melan 1 manufactured by Hitachi, Ltd.)
3) A solid content of 30 parts was dissolved in a mixed solvent of methyl ethyl ketone / toluene / anone (50 parts / 40 parts / 10 parts) in an amount of 20 wt% based on the weight of the solution, and p-toluenesulfonic acid was used as a catalyst for curing. With a solid content of 100
A coating liquid for a release layer was prepared by adding 3 parts per part. Then, the coating liquid is applied to one surface of the biaxially stretched film with a gravure coater so as to have an application amount of 6 g / m ^{2 based on} the weight of the coating liquid, and dried and cured at 190 ° C. for 1 minute. And a release layer having a thickness of 0.9 μm. The film tension during the application of the coating liquid for the release layer and the heat treatment was 2.
It was 7 MPa.

Next, 80 parts of a copolymerized polyester resin (solid content ratio, the same applies hereinafter) and a methylolated melamine resin (SUMIMAL M-40 manufactured by Sumitomo Chemical Co., Ltd.)
W) 15 parts, a surfactant (NS-20 manufactured by NOF Corporation)
8.5) After mixing 5 parts to prepare a 20% by weight aqueous solution, a carbon black aqueous dispersion (HM, manufactured by Mikuni Color Co., Ltd.)
K- # 7360) was added as carbon black so as to be 6.5% by weight in the coloring layer to prepare a coating solution for the coloring layer. Then, the colored layer coating solution is applied to the other surface of the polyester film, which is different from the surface on which the release layer is formed, at a coating amount of 7 g / m ^{2 based} on the coating solution amount.
Heat treatment was performed at 30 ° C. for 30 seconds. Table 1 shows the properties of the obtained release film.

Example 2 The composition of the solid content in the coating liquid for the release layer was determined by using cellulose nitrate (FQ, manufactured by Daicel Chemical Industries, Ltd.).
RS1 / 8) 20 parts, 40 parts of epoxy resin (Epicoat 1007 manufactured by Yuka Shell Epoxy Co., Ltd.) and 40 parts of melamine resin (Melan 13 manufactured by Hitachi, Ltd.) were changed to the same operation as in Example 1. Was repeated. Table 1 shows the properties of the obtained release film.

Example 3 The composition of the solid content in the coating liquid for the release layer was determined using cellulose nitrate (FQ, manufactured by Daicel Chemical Industries, Ltd.).
(RS1 / 8) 80 parts and melamine resin (Melan 13 manufactured by Hitachi, Ltd.) 20 parts, except that the same operation as in Example 1 was repeated. Table 1 shows the properties of the obtained release film.

[Comparative Example 1] The composition of the solid content in the coating solution for the release layer was determined by using cellulose nitrate (FQ, manufactured by Daicel Chemical Industries, Ltd.).
RS1 / 8) 10 parts, epoxy resin (Eicoat 1007 manufactured by Yuka Shell Epoxy Co., Ltd.) 50 parts and melamine resin (Melan 13 manufactured by Hitachi, Ltd.) 40 parts were changed to the same operation as in Example 1. Was repeated. Table 1 shows the properties of the obtained release film.

[Comparative Example 2] The composition of the solid content in the coating solution for the release layer was determined using cellulose nitrate (FQ, manufactured by Daicel Chemical Industries, Ltd.).
(RS1 / 8) and 10 parts of melamine resin (Melan 13 manufactured by Hitachi, Ltd.) were repeated, except that the operation was changed to 10 parts. Table 1 shows the properties of the obtained release film.

Example 4 The same operation as in Example 1 except that polyethylene terephthalate was replaced by polyethylene-2,6-naphthalate having an intrinsic viscosity of 0.62 measured in o-chlorophenol at 25 ° C. Was repeated.
Table 1 shows the properties of the obtained release film.

Comparative Example 3 The same operation as in Example 1 was repeated, except that the film tension when performing the heat treatment at 150 seconds for 30 seconds was changed to 5.0 MPa. Table 1 shows the properties of the obtained release film.

Comparative Example 4 The same operation as in Comparative Example 1 was repeated, except that the treatment for forming the colored layer after forming the release layer was not performed. Table 1 shows the properties of the obtained release film.

Example 5 The same operation as in Example 1 was repeated, except that the amount of carbon black in the colored layer was changed to 10% by weight. Table 1 shows the properties of the obtained release film.

Example 6 The same operation as in Example 1 was repeated, except that the amount of carbon black in the colored layer was changed to 3% by weight. Table 1 shows the properties of the obtained release film.
Shown in

Example 7 A coating liquid for a colored layer was coated with a copolymerized polyester resin (Espel 151 manufactured by Hitachi Chemical Co., Ltd.).
0), 30 parts of melamine resin (Niwalac NS-11, Sanwa Chemical Co., Ltd.), Pigment Black 26 (Fe-Cu-Mn composite oxide) as a black inorganic pigment,
C. I. 77494), and prepared with a mixed solvent of methyl ethyl ketone and toluene (ratio 1/1) so as to have a concentration of 30%. The mixed solution was subjected to sand pigment grinder milling (dispersion machine) to reduce the average particle size of the pigment. The dispersion was dispersed to 0.5 μm to obtain a colored coating liquid. The solid content concentration of the obtained coating liquid was 25%, except that p-toluenesulfonic acid was added to this coating liquid as a curing acceleration catalyst in an amount of 2.5 parts to 100 parts of the resin component. The same operation as in Example 1 was repeated. Table 1 shows the properties of the obtained release film.

Example 8 The addition amount of the black inorganic pigment was 25
The same operation as in Example 7 was repeated except that the parts were changed. Table 1 shows the properties of the obtained release film.

Example 9 The same operation as in Example 7 was repeated, except that the addition amount of the black inorganic pigment was changed to 4 parts.
Table 1 shows the properties of the obtained release film.

Example 10 A coating solution for a colored layer was prepared using cellulose nitrate (FQRS1 / 8, manufactured by Daicel Chemical Industries, Ltd.).
4 parts, 18 parts of epoxy resin (Epicoat 1007 manufactured by Yuka Shell Epoxy Co., Ltd.), 26 parts of melamine resin (Melan 13 manufactured by Hitachi, Ltd.) and Fe-Cu-Mn
A solid content consisting of 12 parts of a black inorganic pigment (pigment black 26, CI 77494) composed of a composite oxide was mixed with methyl ethyl ketone / toluene / anone (50 parts /
40 parts / 10 parts) of the mixed solvent based on the weight of the solution.
The same operation as in Example 1 was repeated except that 0 wt% was dissolved and p-toluenesulfonic acid was added as a curing acceleration catalyst to 3 parts per 100 parts of solid content. Table 1 shows the properties of the obtained release film.

[0048]

[Table 1]

Consider Table 1 below. The release films of Examples 1 to 10 exemplified as the release film of the present invention have excellent dimensional stability and anti-migration property of the release agent, but have a proper adhesion with a peel strength exceeding 25 mN / 5 cm. In particular, the content of the fibrous resin is 1 /
Those with 3 or more were excellent in peel strength exceeding 30 mN / 5 cm. Moreover, since the colored layer, which is a means for solving the second problem of the present invention, is provided on a surface different from the release layer of the polyester film, the suitability for detection is extremely excellent. In particular, Example 10 in which the colored layer is composed of a curable resin and a cellulose resin similarly to the release layer
Was a release film excellent in flatness with less curl because the thermal deformations of the colored layer side and the release layer side were similar.

In contrast to these examples, Comparative Examples 1 and 4 in which the content of the fibrous resin was small, had a peel strength of at most 15 m.
It was only N / 5 cm and easily peeled off. In particular, Comparative Example 4 having no colored layer also had poor detection suitability. On the other hand, in Comparative Example 2 in which the fibrous resin was excessively added, the peel strength was excessively increased, and conversely, the bonding strength between the polyester film and the release layer was weakened. Peeling occurred between the two.
In Comparative Example 3 in which the tension during the heat treatment exceeded 4 MPa,
Poor dimensional stability, wrinkles and sagging occurred,
The peel strength was poorer than that of.

[0051]

As the release agent constituting the release film, conventionally, a silicone resin, a fluorine resin, a resin having a long-chain alkyl group, a thermosetting resin such as melamine or epoxy, a wax or an oil is used. Has been
When used as a protective film such as prepreg,
Silicone resin and thermosetting resin have too low peel strength to easily peel off the protective film.Fluorine resin is difficult to handle due to environmental destruction and safety to human body, and resin with long chain alkyl group has heat resistance. There are also problems such as poor transfer of wax and oil to products such as prepreg.

On the other hand, according to the present invention, a curable resin containing a fibrous resin is employed as the resin constituting the release layer, and thus there is a problem in environmental destruction and safety to the human body. In addition, while having an appropriate peel strength, transfer to a product such as a prepreg of a release layer is prevented. In addition, since both the fibrous resin and the thermosetting resin have excellent heat resistance, they can be sufficiently subjected to heat treatment. At this time, the film tension is set to 4 MPa or less, and the dimensional stability is extremely excellent. A release film is provided.

In addition, the total light transmittance of the release film is 2
The colored layer exemplified in the present invention is provided on the surface on the side opposite to the release layer so that the transmittance variation when irradiating light rays of each wavelength of 5 to 75% and 400 to 900 nm can be -5 to 5%. Accordingly, a release film excellent in detection suitability with an inspection machine or the like and a protective film for prepreg using the same are also provided.

Front page of the continued F-term (reference) 4F100 AA00C AA17C AA21C AA22C AA23C AA24C AA37 AJ06A AK01A AK01C AK25A AK33A AK36A AK41A AK41B AK41J AK42 AK49A AK51A AK53 AK53A AL01 AR00A AR00C BA03 BA07 BA10A BA10C CA13C CA18 DG01A GB90 JB12A JL10C JL14A JN08C YY00 YY00A YY00C

Claims (7)

[Claims] 1. A method comprising a fibrous resin and a curable resin,
15-85% by weight of the former and 85-15% by weight of the latter
The release layer contained is a release film formed on one surface of the polyester film, and the absolute value of the dimensional change rate when heated and cooled from room temperature to 170 ° C. under a stress of 0.785 MPa is as follows: A release film, wherein the following formulas are satisfied in the forming direction of the polyester film and the width direction perpendicular thereto. (Equation 1) Here, l _c in the above formula indicates a dimension at 30 ° C. during cooling, and l _h indicates a dimension at 30 ° C. during heating. 2. A polyester film having a coloring layer formed on the other surface thereof and comprising a colorant-containing organic resin, wherein the total light transmittance of the whole release film is 25 to 75% and 4
The release film according to claim 1, wherein the transmittance variation when irradiating light beams of each wavelength of 00 to 900 nm is in a range of -5 to 5%. 3. The organic resin constituting the colored layer comprises a fibrous resin and a curable resin.
3. The release film according to claim 2, wherein the latter is contained in an amount of 85 to 15% by weight. 4. The cellulose resin comprises cellulose nitrate, cellulose acetate, cellulose sulfate, sodium cellulose xanthate, cellulose ester, methyl cellulose, ethyl cellulose, cellulose acetyl butyrate, cellulose acetyl propionate, carboxymethyl cellulose and hydroxyethyl cellulose. 4. The release film according to claim 1, which is at least one member selected from the group. 5. The thermosetting resin is at least one thermosetting resin selected from the group consisting of melamine resin, epoxy resin, phenol resin, polyurethane resin, polyimide resin, alkyd resin, urea resin and acrylic resin. The release film according to claim 1. 6. The colorant is Ti, V, Cr, Mn, F
The release film according to claim 2, which is a black inorganic pigment comprising at least one oxide selected from the group consisting of e, Co, Ni, and Cu. 7. A protective film for prepreg, wherein the release film according to claim 1 is used.