JP2018090737A - Release sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a release sheet excellent in releasability as well as excellent in followability to a metal mold.SOLUTION: A release sheet includes a domain of a fluororesin in a matrix of a polypropylene resin. A mass ratio (A)/(B) is preferably over 1.0 and less than 20 with regard to a compounding ratio if the polypropylene resin is (A), and the fluororesin is (B).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a release sheet, and more particularly to a release sheet used in a molding apparatus.

  In a resin molding process using a molding apparatus, a release sheet is sandwiched between a mold and a mold resin and used to release the molded mold resin and the mold. For example, a release sheet containing a thermoplastic tetrafluoroethylene copolymer or a polystyrene resin is disclosed as such a release sheet (see, for example, Patent Documents 1 and 2).

International Publication No. 2013/094752 International Publication No. 2015/190386

  The release sheet is generally brought into close contact with the surface of the mold by vacuum suction. However, the release sheets so far have a certain release property, but are not necessarily sufficient in terms of followability (elongation) to the mold shape. For example, conventional release sheets may be torn if they are greatly stretched at the corners of the mold. If the release sheet is torn, the resin leaks from the part and contaminates the mold. In particular, in the manufacture of so-called power semiconductor modules used in the energy field and automobile field, the thickness of the mold resin tends to increase and the depth of the mold tends to increase, and the stress applied to the release sheet at the corners also increases. However, conventional release sheets have not been able to cope with them sufficiently.

  An object of this invention is to provide the release sheet which is excellent in mold release property and is excellent also in the followable | trackability to a metal mold | die.

  As a result of intensive studies by the present inventors to solve the above-mentioned problems, by forming a fluororesin domain in a polypropylene resin matrix, it is excellent in releasability and excellent conformability to a mold. The present inventors have found that a release sheet can be obtained. More specifically, the present invention provides the following.

  (1) The present invention is a release sheet having a fluororesin domain in a polypropylene resin matrix.

  (2) Further, in the present invention, when the polypropylene resin is (A), the fluororesin is (B), and the blending ratio is expressed as (A) / (B) by mass ratio, more than 1.0 It is a release sheet as described in (1) below.

  (3) Moreover, this invention is a release sheet as described in (1) or (2) whose domain of the said fluororesin is a fiberized state.

  (4) Moreover, this invention is a release sheet in any one of (1) to (3) whose said fluororesin is unbaking.

  (5) Moreover, this invention is a release sheet in any one of (1) to (4) whose said fluororesin is polytetrafluoroethylene resin.

  (6) Moreover, this invention is a release sheet as described in (1) or (2) whose said polypropylene resin is a homo polypropylene resin.

  (7) The present invention includes a mixing step of melt kneading and mixing a polypropylene resin and a fluororesin having an average particle size of 0.5 μm or more and 10 μm or less, and in the matrix of the polypropylene resin, A release sheet manufacturing method including a forming step of forming a sheet with a domain.

  (8) Moreover, this invention is a manufacturing method of the release sheet as described in (7) whose said fluororesin is a bulk density of 800 g / L or less.

  The present invention can provide a release sheet that is excellent in releasability and excellent in followability to a mold.

(A) is a SEM image which shows an observation image when the surface of the release sheet of Example 1 is observed with a scanning electron microscope (SEM) at a magnification of 500 times, and (b) scans a cross section of the release sheet. It is a SEM image which shows an observation image when it observes by 500 times of magnification with an electron microscope (SEM). (A) is a SEM image which shows an observation image when the surface of the release sheet of Comparative Example 1 is observed with a scanning electron microscope (SEM) at a magnification of 500 times, and (b) is a cross-sectional view of the release sheet. It is a SEM image which shows an observation image when it observes by 500 times of magnification with an electron microscope (SEM). It is a graph which shows the elongation behavior of the release sheet of the Example and comparative example which were measured with the tension tester. It is a graph which shows the elongation behavior of the release sheet of the Example and comparative example which were measured with the thermomechanical analyzer (TMA). It is a graph which shows the behavior of the release sheet of the Example and comparative example which were measured with the differential scanning calorimeter (DSC). It is a graph which shows the behavior of the release sheet of the Example and comparative example which were measured with the differential thermothermal weight simultaneous measuring apparatus (TG-DTA). It is a graph which shows the behavior of the release sheet of the Example and comparative example which were measured with the infrared spectroscopy analyzer (IR).

  Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments. The present invention can be implemented with appropriate modifications within the scope of the object.

<Release sheet>
The release sheet according to the present embodiment is a release sheet used between a mold and a mold resin in a molding resin molding process using a molding apparatus. The release sheet according to the present embodiment has a fluororesin domain in a polypropylene resin matrix. For example, as shown in FIG. 1, in a release sheet, domains (islands) occupying a specific region are dispersed in a matrix (sea) (hereinafter, this structure is referred to as a matrix domain structure). Here, the ratio of domains having a particle size of 0.5 μm or more and 10 μm or less in the matrix is 0.001% or more and 20% or less. Here, the particle diameter is, for example, a value calculated by an average value of the major axis and the minor axis of the domain observed with a scanning electron microscope (SEM) or a transmission electron microscope (TEM).

  The release sheet according to the present embodiment is excellent in releasability and conformability to a mold because the polypropylene resin and the fluororesin have a matrix domain structure. The domain of the fluororesin can impart releasability without hindering the followability (elongation) of the polypropylene resin matrix.

  When fluorine is contained in the resin constituting the release sheet, it can also be contained in a copolymer such as ethylene-tetrafluoroethylene copolymer (ETFE). However, in such a case, although releasability can be imparted, the extensibility decreases as the fluorine content increases, and it is difficult to achieve both releasability and followability to the mold. . On the other hand, when the resin constituting the release sheet contains a fluororesin as a domain, surprisingly, even if the fluorine content increases, the extensibility does not decrease, and the mold release and mold It became clear that it would be compatible with follow-up performance.

  The matrix domain structure of the present application is obtained by mixing (blending) polypropylene resin and fluororesin at a predetermined blending ratio and forming a film at a temperature not lower than the melting point of the polypropylene resin and lower than the melting point of the fluororesin. It is done. In this case, as described in Examples and Comparative Examples described later, SEM image observation, thermal analysis (DSC, TG, DMA), infrared spectroscopic analysis (IR) are distinguished from copolymers such as ETFE. The two can be clearly distinguished from each other. For example, in DSC, the matrix domain structure of the present application has a melting point of polypropylene resin (for example, 130 ° C. to 165 ° C., 165 ° C. for homopolypropylene) and a fluororesin (depending on the amount of fluorine, for example, 250 ° C. to 350 ° C. The following two peaks are clearly observed depending on the blending ratio (see Examples). On the other hand, in the case of a copolymer such as ETFE, the two peaks are not clearly observed, and both can be easily distinguished.

  The release sheet according to the present embodiment has an elongation in the longitudinal direction measured at a tensile rate of 50 mm / min using an Instron type tensile tester on a test piece of length 20 mm × width 10 mm under heating at 140 ° C. Followability (extensibility) can be realized, in which the tensile load when the ratio is 200% or more is 3 N / 10 mm or less.

  Further, the release sheet according to the present embodiment is more than 1.0 when the polypropylene resin is (A), the fluororesin is (B), and the blending ratio is expressed as (A) / (B) by mass ratio. It is preferably 20 or less, more preferably 4 or more and 10 or less. When the blending ratio of the polypropylene resin and the fluororesin is within the above range, it is easy to achieve both releasability and followability to the mold. When the said compounding ratio becomes too small, it exists in the tendency for the followable | trackability to a metal mold | die to fall. When the said compounding ratio becomes excessive, it exists in the tendency for a mold release property to fall.

  In particular, the domain of the fluororesin is preferably in a fiberized state. Here, the fiberization of the fluororesin refers to a form in which the fluororesins in the form of fibers are intertwined to form a domain, or the domain of the fluororesin in the form of a fiber is entangled with the polypropylene resin. To do. It is considered that the fiberized fluororesin domain can impart releasability while complementing the followability (elongation) of the polypropylene resin matrix.

  Hereinafter, each component will be described.

[Fluororesin]
The fluororesin is not particularly limited as long as it is a fluorine-containing resin, but from the viewpoint of releasability and heat resistance, a fluoroolefin polymer is preferable, and polytetrafluoroethylene (PTFE) is particularly preferable. Here, the fluoroolefin polymer is a polymer having units based on a fluoroolefin.

  Examples of the fluoroolefin include tetrafluoroethylene (TFE), vinyl fluoride (VDF), vinylidene fluoride, trifluoroethylene, hexafluoropropylene, chlorotrifluoroethylene (CTFE) and the like. A fluoroolefin may be used individually by 1 type, and may be used together 2 or more types.

  Examples of fluoroolefin polymers include ethylene-tetrafluoroethylene copolymer (ETFE), ethylene-chlorotrifluoroethylene copolymer (ECTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene. -Perfluoro (alkyl vinyl ether) copolymer (PFA), tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV) and the like. A fluoroolefin polymer may be used individually by 1 type, and may be used together 2 or more types.

  The fluoroolefin polymer may further have units other than the units based on the fluoroolefin. For example, the unit other than the unit based on fluoroolefin may be an ethylenic monomer unit having no fluorine. For example, the ethylenic monomer may be an ethylenic monomer having 5 or less carbon atoms, and specifically includes ethylene, propylene, 1-butene, vinyl chloride, vinylidene chloride and the like.

  The fluororesin is preferably unfired. “Unfired fluororesin” refers to a fluororesin that has no history of firing beyond the melting point. The unfired fluororesin has flexibility in the resin itself as compared with the fired fluororesin, and the fiberization is easily exhibited when a shearing force is applied by kneading or the like. The unfired fluororesin includes those obtained by suspension polymerization and those obtained by emulsion polymerization, and those obtained by emulsion polymerization are particularly preferable.

[Polypropylene resin]
Preferred examples of the polypropylene resin include homopolypropylene resins, random polypropylene resins, block polypropylene resins, and α-olefin copolymers having a polypropylene crystal part and having 2 to 20 carbon atoms other than propylene. In addition, a propylene-α-olefin copolymer containing 15 mol% or more of ethylene, 1-butene, 1-hexene, 1-octene, 3-methyl-1-butene, 4-methyl-1-pentene, etc., for example, ethylene / Also included are propylene copolymers, ethylene / propylene / butene copolymers, and the like. As the polypropylene resin, the melting point may be adjusted in accordance with the molding temperature, but from the viewpoint of heat resistance, a homopolypropylene resin having a melting point of 165 ° C. is preferable. Homopolypropylene resin has a higher melting point and better heat resistance than random polypropylene resin.

[Thickness of release sheet]
The thickness of the release sheet is preferably 25 μm or more and 200 μm or less, and more preferably 50 μm or more and 150 μm or less. When the thickness of the release sheet is within the above range, the release sheet can be easily deformed and has excellent followability to the mold. If the thickness of the release sheet is too small, it tends to be easily broken at the corners of the mold. If the thickness of the release sheet is excessive, the release sheet is not easily deformed, and wrinkles are likely to occur in the resin molded product. The thickness of the release sheet is a value measured in accordance with JIS K7130 (plastic-film and sheet-thickness measuring method).

[Other aspects]
The release sheet according to the present embodiment may further include other layers as long as the release property and the followability to the mold are not impaired. Examples of the other layer include an antistatic layer. When the antistatic layer is provided, it is possible to suppress the dust from being adsorbed by charging the release sheet, and when manufacturing a molded resin molded product such as a semiconductor module, a part of the semiconductor element is Even in the case of direct contact with the release sheet, the destruction of the semiconductor element due to the charge-discharge of the release sheet can be suppressed. The surface resistance value of the antistatic layer, from the viewpoint of antistatic, preferably ¹⁰ 10 Ω / □ or less, more preferably 10 ⁹ Ω / □ or less.

  Examples of the antistatic layer include a layer containing an antistatic agent. As the antistatic agent, a polymer antistatic agent is preferable. Examples of the polymer antistatic agent include a cationic copolymer having a quaternary ammonium base in the side group, an anionic polymer containing polystyrene sulfonic acid, polyether ester amide, ethylene oxide-epichlorohydrin, polyether ester, etc. Nonionic polymers, π-conjugated conductive polymers, and the like. These may be used alone or in combination of two or more.

  Note that the release sheet according to the present embodiment has an antistatic agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a lubricant, an inorganic filler, coloring, in addition to the above-described polypropylene resin and fluororesin, depending on the required properties. Additives such as an agent, a crystal nucleating agent and a flame retardant may be contained.

<Method for producing release sheet>
The method for producing a release sheet according to the present embodiment includes a mixing step in which a polypropylene resin and a fluororesin are melt-kneaded and mixed, and a polypropylene resin matrix is molded into a sheet shape with a fluororesin domain. Forming step.

  The fluororesin applied to the mixing step preferably has an average particle size of 0.5 μm to 10 μm, and more preferably 1.5 μm to 5 μm. When the average particle diameter is in the above range, it is easy to achieve both the release property and the followability of the release sheet. When the average particle size is excessive, surface irregularities tend to be large. If the average particle size is too small, mixing tends to be difficult due to aggregation or the like. In addition, an average particle diameter shall be a volume average particle diameter. The volume average particle size can be measured by laser diffraction type or laser scattering type particle size distribution measurement.

  Moreover, as a fluororesin used for a mixing process, it is preferable that a bulk density is 800 g / L or less, and it is more preferable that it is 200 g / L or more and 500 g / L or less. If the bulk density is in the above range, it is easy to achieve both the release property of the release sheet and the followability to the mold. If the bulk density is excessive, it tends to be hard and the followability tends to be poor. If the bulk density is too low, handling in the mixing process tends to be poor. In the present specification, the bulk density is a value measured according to ASTM D4894.

  The method of melt kneading performed in the mixing step is not particularly limited, and can be performed using a melt kneading apparatus such as an extruder that is generally commercially available. The cylinder temperature of the part to be kneaded is a temperature not lower than the melting point of the polypropylene resin and lower than the melting point of the fluororesin. For example, it is usually 200 ° C to 250 ° C, preferably 210 ° C to 230 ° C. The kneading time is usually 30 seconds to 10 minutes, preferably 1 minute to 5 minutes. If the temperature is too low or the kneading time is too short, kneading becomes insufficient due to insufficient melting, and if the temperature is too high or the kneading time is too short, the polypropylene resin may be thermally decomposed, which is not preferable.

  The molding method performed in the molding step is not particularly limited, and a known production method such as a melt extrusion method can be employed. In the melt extrusion method, there are a T-die method of extruding from a T-die and forming into a sheet shape, an inflation method in which air is blown at the same time as extrusion using a ring-shaped circular die, and a tubular film is formed. The T-die method is preferable in terms of high sheet thickness accuracy.

<Method for producing molded product of mold resin>
The method for producing the molded product of the mold resin is such that the mold temperature is not lower than the melting point of the polypropylene resin −100 ° C. and not higher than the melting point, and the release sheet described above is interposed between the mold and the mold resin. Mold resin is molded. The maximum thickness of the molded resin after molding may be 0.5 mm or more.

  As a method for producing a molded product of the mold resin, a known production method can be adopted except that the above-described release sheet is used. For example, a semiconductor module is arranged in an upper mold, a release sheet in which a mold resin made of a thermosetting resin is placed in a lower mold heated to a predetermined temperature, and a cavity surface of the lower mold Vacuum on the side. Then, by lowering the upper mold, the mold is clamped, and the cavity formed between the upper mold and the lower mold is filled with the mold resin and cured. Thereafter, the upper mold is raised, the semiconductor module sealed with the mold resin is taken out, and the release sheet is peeled off.

  As described above, since the release sheet according to the present embodiment is excellent in releasability, a release agent is added to the curable resin constituting the mold resin, or a mold having a special structure is used. Even if it is not, good mold release from the mold of the mold resin can be realized. In addition, since the release sheet according to the present embodiment has excellent followability to the mold, the depth of the mold is deep, for example, even when the thickness of the mold resin is as deep as 5 mm or more, it is complicated. Even a mold with a simple shape can follow without tearing. Therefore, it is difficult to cause a problem that the release sheet is broken and the mold is contaminated with the mold resin.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these.

[Examples 1 to 3]
Homopolypropylene resin (trade name: Prime Polypro F135, manufactured by Prime Polymer Co., Ltd., melting point: 165 ° C.) and fluororesin (trade name: Line Plus PF150-PH, manufactured by Maflon Co., Ltd., average particle size: 2.6 μm, bulk density: 320 g / L, melting point: 335 ° C.) at a blending ratio shown in Table 1 and melt-extruded at 230 ° C. with an extruder equipped with a T-die having an adjusted lip opening degree. A release sheet (PP + fluorine) having a thickness of 90 to 110 μm was obtained by adjusting the film speed and the nip pressure.

[Comparative Example 1]
A homopolypropylene resin (trade name: Prime Polypro F135, manufactured by Prime Polymer Co., Ltd.) was melt-extruded under the same conditions as in the Examples to obtain a release sheet (PP) having a thickness of 90 to 110 μm.

[Comparative Example 2]
Since the melting point of the fluororesin (trade name: Line Plus PF150-PH, manufactured by Maflon) is 335 ° C., melt extrusion cannot be performed only from the fluororesin.

[Comparative Example 3]
Polyamide synthetic resin (nylon 66) (trade name: 5033, manufactured by Ube Industries, melting point: 196 ° C.) and fluororesin (trade name: Line Plus PF150-PH, manufactured by Maflon) are shown in Table 1. And extruding at 230 ° C by an extruder equipped with a T-die with an adjusted lip opening, adjusting the master roll, film formation speed, and nip pressure, and releasing from 90 to 110 µm in thickness A sheet was obtained.

[Comparative Example 4]
Acrylonitrile-butadiene-styrene copolymer synthetic resin (ABS resin) (trade name: AE850, manufactured by Asahi Kasei Co., Ltd., melting point: 115 ° C.) and fluororesin (trade name: Line Plus PF150-PH, manufactured by Maflon) Thickness of 90mm by adjusting the master roll, film forming speed, and nip pressure by extrusion at 230 ° C using an extruder equipped with a T-die mixed at the mixing ratio shown in Fig. 1 and adjusted in lip opening A release sheet of ˜110 μm was obtained.

[Comparative Example 5]
A sheet made of an ethylene-tetrafluoroethylene copolymer (trade name: Aflex 100N1250T, manufactured by Asahi Glass Co., Ltd.) (indicated in Table 1 as an ETFE sheet) was used as a release sheet.

[Comparative Example 6]
A sheet made of polystyrene (trade name: Eudis CA-F10, manufactured by Kurabo Industries) (denoted as PS sheet in Table 1) was used as a release sheet.

[Measurement / Evaluation]
The release sheets of Examples 1 to 3 and Comparative Examples 1 to 6 were evaluated for sheeting, followability, and release properties for the mold resin and the mold. The results are shown in Table 1. Moreover, the SEM image which shows an observed image when the surface and cross section of the release sheet of Example 1 and Comparative Example 1 are observed with a scanning electron microscope (SEM) at a magnification of 500 is shown in FIG. 1 and FIG.

(Sheet)
It was verified whether sheet formation by melt extrusion was possible. Those that can be made into sheets are marked with ◯, and those that are difficult to make into sheets are marked with X.

(Followability)
A test piece having a length of 20 mm × width of 10 mm was prepared from the release sheets obtained in Examples and Comparative Examples, and 140 ° C. (actual measurement value) using a tensile tester (type 5565, manufactured by Instron Japan). Under the heating, a tensile load was measured when the longitudinal displacement rate measured at a tensile speed of 50 mm / min was 200% or more. And the followability (elongation) was evaluated according to the following criteria.
◯: The tensile load is 3 N / 10 mm or less. Δ: The tensile load is more than 3 N / 10 mm. X: Fracture before the displacement rate reaches 200%.

  In addition, the elongation behavior when the test piece of the release sheet of Example 1 and Comparative Examples 5 and 6 is pulled under the above conditions (constant temperature, constant speed) with an Instron type tensile tester is shown in FIG. Here, the displacement rate is calculated as “measurement length−initial length (20 mm) / initial length (20 mm)”.

  In addition, the specimens of the release sheets of Example 1 and Comparative Examples 5 and 6 were pulled while varying the temperature with a constant load (1.4 N) by a thermomechanical analyzer (TMA) in accordance with JISK7197 and ASTM D696. FIG. 4 shows the elongation behavior at the time. Here, the displacement rate (TMA) is calculated by “length during measurement−initial length (20 mm) / initial length (20 mm)”.

(Releasability from mold resin)
A test piece having a length of 60 mm, a width of 12 mm, and a thickness of 100 μm was prepared from the release sheets obtained in Examples and Comparative Examples. Then, on a hot plate set at 180 ° C., a glass plate having a thickness of 3.2 mm, a test piece, and 4 g of epoxy resin were placed in this order, 1 kg of weight was placed from above, and heated for 5 minutes. Thereby, an epoxy resin plate having a thickness of 2 mm was formed on the test piece. Then, after the epoxy resin plate was cooled, the peelability between the test piece and the epoxy resin plate was evaluated according to the following criteria.
A: The test piece peels off without applying force. 〇: The test piece peels off with a little force. X: The test piece does not peel off even when force is applied, or the test piece is destroyed.

(Releasability from mold)
A test piece having a length of 60 mm, a width of 12 mm, and a thickness of 100 μm was prepared from the release sheets obtained in Examples and Comparative Examples. Then, on a hot plate set at 180 ° C., a stainless steel plate (SUS304) having a thickness of 3.2 mm, a test piece, and 4 g of epoxy resin were placed in this order, and 1 kg of weight was placed from above and heated for 5 minutes. Thereby, an epoxy resin plate having a thickness of 2 mm was formed on the test piece. And after the epoxy resin plate was cooled, the peelability between the test piece and the stainless steel plate was evaluated according to the following criteria.
A: The test piece peels off without applying force. 〇: The test piece peels off with a little force. X: The test piece does not peel off even when force is applied, or the test piece is destroyed.

  The release sheets of Example 1 and Comparative Examples 1 and 5 were measured with a differential scanning calorimeter (DSC), a differential thermothermal gravimetric simultaneous measurement device (TG-DTA), and an infrared spectroscopic analyzer (IR). The results are shown in FIGS.

  From the comparison between FIG. 1 and FIG. 2, in the release sheet of Example 1 in which a polypropylene resin and a fluororesin are melt-kneaded, the polypropylene resin becomes a matrix and the fluororesin becomes a domain and is formed into a sheet shape. Recognize.

  Further, from the results of Table 1, in Examples 1 to 3 using a release sheet having a fluororesin domain in a polypropylene resin matrix, the mold resin and the mold are excellent in releasability and followability ( (Extensibility) was confirmed to be excellent. In particular, in Examples 1 and 2 using a release sheet in which the blending ratio of the fluororesin was 10% by mass or more, it was confirmed that the release property was excellent.

  On the other hand, in Comparative Example 1 using a release sheet composed of 100% by mass of polypropylene resin, the followability was excellent, but the release property was insufficient. In Comparative Example 2 using a release sheet composed of 100% by mass of a fluororesin, it was difficult to form a sheet by melt extrusion because the melting point of the fluororesin was high. In Comparative Examples 3 and 4 using a release sheet having a fluororesin domain in a matrix of nylon 66 or ABS resin, the surface tension was smaller than that of polypropylene resin, and the releasability from the mold resin was poor.

  In Comparative Example 5 using a release sheet made of an ETFE sheet, the mold release property was excellent, but it did not have a matrix domain structure, and the followability (elongation) was insufficient. In addition, from the results of Table 1 and FIG. 3, in Comparative Example 6 using a release sheet made of a PS sheet, the mold release property is excellent, but it breaks before the displacement rate reaches 150%, and the followability is good. (Elongation) was bad.

  Further, from the results of FIG. 4, in Example 1 using a release sheet having a fluororesin domain in a polypropylene resin matrix, Comparative Examples 5 and 6 using release sheets composed of ETFE sheets and PS sheets were used. In comparison, it was confirmed that followability (elongation) was exhibited with a small load from a relatively low temperature of over 100 ° C.

  From the results of differential scanning calorimetry (DSC) shown in FIG. 5, in Example 1 using a release sheet having a fluororesin domain in a polypropylene resin matrix, the peak of the polypropylene resin and the fluororesin have. Two peaks were clearly observed. On the other hand, in Comparative Example 1 using the release sheet made of PP sheet, only one peak is observed, and in Comparative Example 5 using the release sheet made of ETFE sheet, there is one gentle peak. It was confirmed that the behavior was different from that of Example 1.

  Further, in Example 1 using a release sheet having a fluororesin domain in a polypropylene resin matrix from the thermogravimetric simultaneous measurement apparatus (TG-DTA) shown in FIG. Two possible changes in weight were observed. On the other hand, in Comparative Examples 1 and 3 using a release sheet composed of a PP sheet and a PTFE sheet, one stage of weight change was observed at each different temperature, and it was confirmed that the behavior was different from that in Example 1. .

  Further, from the results of the infrared spectroscopic analyzer (IR), Example 1 using a release sheet having a fluororesin domain in a polypropylene resin matrix, and Comparative Example 1 using a release sheet made of a PP sheet In Comparative Example 5 using a release sheet made of PTFE and PTFE sheets, it was confirmed that each had a specific peak and could be clearly distinguished from each other.

Claims (8)

  A release sheet having a fluororesin domain in a polypropylene resin matrix.   The polypropylene resin is (A), the fluororesin is (B), and the blending ratio is expressed as (A) / (B) by mass ratio, which is more than 1.0 and 20 or less. Release sheet.   The release sheet according to claim 1, wherein the fluororesin domain is in a fiberized state.   The release sheet according to any one of claims 1 to 3, wherein the fluororesin is unfired.   The release sheet according to any one of claims 1 to 4, wherein the fluororesin is a polytetrafluoroethylene resin.   The release sheet according to claim 1, wherein the polypropylene resin is a homopolypropylene resin. A mixing step of melt kneading and mixing a polypropylene resin and a fluororesin having an average particle size of 0.5 μm or more and 10 μm or less;
A mold release sheet manufacturing method comprising: forming a sheet in a state of having the fluororesin domain in the polypropylene resin matrix.   The said fluororesin is a manufacturing method of the release sheet of Claim 7 whose bulk density is 800 g / L or less.