JP6508884B2 - Polystyrene-based release film having rough surface and method for producing the same - Google Patents

Description

  The present invention relates to a biaxially oriented syndiotactic polystyrene-based release film having a rough surface.

  Since syndiotactic polystyrene (SPS) resins are excellent in heat resistance and chemical resistance, their applications as molded articles and films are expanding in various fields. As one of such applications, it is molded when manufacturing printed circuit boards, ceramic electronic parts, semiconductor packages, and other various resin molded products by using the characteristics of SPS-based resin that surface tension is low and wettability is low. It has been studied to use a biaxially oriented SPS-based film as a release film for preventing fusion between a mold and a molding roll and a material to be molded.

  In such a release film, in order to give a matte appearance to the surface of a molded product, the release film may be roughened to transfer the surface irregularities to the molded product. For example, Patent Documents 1 to 3 describe that a release film or a transfer film formed of a single layer film of SPS resin or a multilayer film including the SPS resin layer is roughened.

JP, 2013-216779, A Unexamined-Japanese-Patent No. 2013-215989 JP, 2011-094268, A

  As a method of roughening a biaxially oriented SPS-based film, there is conventionally known a method of pressing the film onto a metal roll whose surface is engraved in a matte tone and transferring the unevenness of the roll surface to the film surface. However, since a roughening step is required separately from the orientation step, there is room for improvement in terms of manufacturing cost.

  The present invention has been made in consideration of the above, and an object thereof is to provide a biaxially oriented SPS-based film whose surface is roughened more inexpensively.

  The roughened polystyrene-based release film of the present invention contains a syndiotactic polystyrene-based resin and a styrene-based thermoplastic elastomer, and is biaxially oriented.

  Preferably, the polystyrene-based release film having the rough surface has a glossiness of 90% or less. Here, the degree of gloss refers to the 60-degree specular gloss, Gs (60 °) defined in JIS Z 874: 1997. As the glossiness in the present invention, the average value of the values in the longitudinal direction (MD) and the transverse direction (TD) is used.

  In addition, preferably, the polystyrene-based release film having a rough surface has a tensile elongation at 175 ° C. of 40% or more. Here, the tensile elongation refers to the elongation when the sample is broken by a tensile test method described later. The tensile elongation is preferably 40% or more in each of the machine direction (MD) and the transverse direction (TD).

  Also preferably, the styrenic thermoplastic elastomer is a hydrogenated styrenic thermoplastic elastomer.

  Preferably, in the polystyrene-based release film having the above-mentioned rough surface, the weight ratio of syndiotactic polystyrene-based resin (a) to styrene-based thermoplastic elastomer (b) is (a) / (b) = 97/3. 60 to 40/40.

  In addition, preferably, all or part of the styrenic thermoplastic elastomer is composed of a soft segment composed of a poly (ethylene / propylene) block or a poly (ethylene-ethylene / propylene) random copolymer block, and a syndiotactic polystyrene resin The weight ratio of (a) to a styrenic thermoplastic elastomer (c) having a poly (ethylene / propylene) block or a poly (ethylene-ethylene / propylene) random copolymer block is (a) / (c) = 97/3 to 3 60/40.

  More preferably, all or part of the styrenic thermoplastic elastomer has a soft segment composed of a poly (ethylene-ethylene / propylene) random copolymer block, and a syndiotactic polystyrene-based resin (a) and poly (ethylene-ethylene) The weight ratio of the styrene-based thermoplastic elastomer (d) having a random copolymer block is (a) / (d) = 97/3 to 60/40.

  The method for producing a polystyrene-based release film having a rough surface according to the present invention comprises the steps of producing a precursor film containing a syndiotactic polystyrene-based resin and a styrene-based thermoplastic elastomer, and simultaneously biaxially stretching the precursor film. And

  According to the present invention, a biaxially oriented syndiotactic polystyrene-based film having a rough surface can be used at lower cost.

It is a figure for demonstrating the evaluation method of the roughened polystyrene type release film of this invention.

  The polystyrene-based film of the present embodiment is a release film whose surface is roughened by blending a syndiotactic polystyrene (SPS) -based resin with a styrene-based thermoplastic elastomer (TPS) and biaxially stretching it. .

  First, the composition of the film of the present embodiment will be described.

  The SPS-based resin is a styrenic polymer having a syndiotactic structure. The syndiotactic structure is a syndiotactic structure, that is, a steric group in which phenyl groups or substituted phenyl groups which are side chains with respect to the main chain formed from carbon-carbon bonds are alternately positioned in opposite directions. Means the structure.

The degree of tacticity (tacticity) of the SPS resin can be quantified by nuclear magnetic resonance ( ¹³ C-NMR) with isotope carbon. The tacticity of the SPS-based resin measured by ¹³ C-NMR method is a chain consisting of several monomer units, for example, diad in the case of two, triad in the case of three, triad in the case of five, and pentad in the case of five. It can be shown by the proportion of reverse syndiotactic configuration (racemic dyad etc.). The SPS-based resin in the present invention is usually at least 75%, preferably at least 85% in racemic dyad, or at least 60%, preferably at least 75% in racemic triad, or at least 30%, preferably 50% in racemic pentad. It is a styrenic polymer having the above syndiotacticity.

  Types of styrene-based polymers as SPS-based resins include polystyrene, poly (alkylstyrene), poly (halogenated styrene), poly (halogenated alkylstyrene), poly (alkoxystyrene), poly (vinyl benzoate), These hydrogenated polymers etc. and these mixtures, or the copolymer which has these as a main component are mentioned. Examples of poly (alkylstyrenes) include poly (methylstyrene), poly (ethylstyrene), poly (isopropylstyrene), poly (tertiary butylstyrene), poly (phenylstyrene), poly (vinyl naphthalene), poly (vinyl styrene) Etc.). Examples of poly (halogenated styrene) include poly (chlorostyrene), poly (bromostyrene), poly (fluorostyrene) and the like. Examples of poly (halogenated alkylstyrene) include poly (chloromethylstyrene) and the like. Examples of poly (alkoxystyrene) include poly (methoxystyrene) and poly (ethoxystyrene).

  The weight average molecular weight of the SPS resin constituting the plastic film according to the present invention is 10,000 to 3,000,000, preferably 30,000 to 1,500,000, and particularly preferably 50,000 to 500,000. It is. The glass transition temperature of the SPS resin is 60 to 140 ° C., preferably 70 to 130 ° C. The melting point of the SPS resin is 200 to 320 ° C., preferably 220 to 280 ° C. In the present specification, the glass transition temperature and the melting point of the resin are values measured according to JIS K 7121.

  The SPS-based resin contained in the release film of the present embodiment may be a mixture of two or more different resins.

  Various commercially available products can be used as the polystyrene-based thermoplastic elastomer (TPS). By blending TPS with the SPS-based resin, flexibility is imparted to the film, and the film is roughened by biaxial stretching. TPS is a thermoplastic elastomer (TPE) in which the hard segment is made of polystyrene, and when it is compounded in an SPS film by this, appearance defects and the like are less likely to occur.

  As TPS, it is preferable to use what was hydrogenated. As a result, the heat resistance of TPS can be improved, and an unexpected reaction can be prevented from occurring in the melting and extruding step of the SPS resin performed at high temperature.

  As hydrogenated TPS, polystyrene-poly (ethylene / butylene) -polystyrene (TPS-SEBS), polystyrene-poly (ethylene / propylene) -polystyrene (TPS-SEPS), polystyrene-poly (ethylene-ethylene / propylene) -polystyrene Various materials having different soft segments, such as (TPS-SEEPS) and polystyrene-poly (ethylene / propylene) -polystyrene (TPS-SEP) can be used.

  The TPS contained in the release film of the present embodiment may be a mixture of two or more different resins. Also, all or part of TPS may be one in which the soft segment is composed of a poly (ethylene / propylene) block or a poly (ethylene-ethylene / propylene) random copolymer block. Among them, it is particularly preferable to use TPS-SEEPS in which the soft segment is composed of a random copolymer of poly (ethylene-ethylene / propylene) for all or part of TPS because the roughening effect of the film is large.

  The compounding amount of TPS is preferably such that the weight ratio of SPS resin (a) to TPS (b) is (a) / (b) = 97/3 to 60/40, and more preferably 97/3 to 65 / It is more preferable to set it as 35, 97 / 3-70 / 30, 97 / 3-80 / 20. If the blending amount of TPS is too small, the effect of roughening and the improvement of flexibility can not be sufficiently obtained. On the other hand, when the blending amount of TPS is too large, the characteristics such as heat resistance, chemical resistance and low surface tension, which are the characteristics of the SPS resin, are lowered.

  When the soft segment is composed of a poly (ethylene / propylene) block or a poly (ethylene-ethylene / propylene) random copolymer block as all or part of TPS, the compounding amount is the SPS resin (a) and The weight ratio of such TPS (c) is preferably (a) / (c) = 97/3 to 60/40, and further preferably 97/3 to 65/35, 97/3 to 70/30, 97 / It is more preferable to set it as 3-80 / 20.

  When TPS-SEEPS is used as all or part of TPS, the compounding quantity is such that the weight ratio of SPS resin (a) to TPS-SEEPS (d) is (a) / (d) = 97 / 3-60 It is preferable to set it as / 40, and it is more preferable to set it as 97 / 3-65 / 35, 97 / 3-70 / 30, 97 / 3-80 / 20. If the blending amount of TPS-SEEPS is too small, the effect of roughening and the improvement of flexibility can not be sufficiently obtained. On the other hand, when the blending amount of TPS-SEEPS is too large, characteristics such as heat resistance, chemical resistance and low surface tension, which are features of the SPS resin, are deteriorated.

  Moreover, you may contain resin other than the above in the range which does not have a practical adverse effect on the heat resistance, chemical resistance, low surface tension etc. which are the characteristics of SPS type | system | group film. Even in that case, the content ratio of the SPS-based resin to the total polymer component in the plastic film is preferably 50% by weight or more, more preferably 60% by weight or more, and particularly preferably 75% by weight or more preferable.

  In addition to the above-mentioned polymers, the release film of this embodiment may be an antioxidant, an ultraviolet light absorber, a light stabilizer, a lubricant, an antistatic agent, an inorganic filler, a colorant, a crystal nucleating agent according to the required characteristics. And additives such as flame retardants. However, when using as a release film at the time of shaping | molding of electronic components, such as a printed circuit board, it is more preferable not to contain the component which may contaminate a to-be-molded product, for example, an inorganic filler.

  Next, the characteristics of the film of the present embodiment will be described.

  The thickness of the release film is preferably 10 to 100 μm because it can be used for many applications and is easy to manufacture and handle. The thickness of the biaxially stretched film used as a release film is typically 50 μm.

  The degree of surface roughening of the film can be represented by the 60-degree specular gloss, Gs (60 °) defined in JIS Z 874: 1997. As an index of the degree of surface roughening, it is also possible to use a measurement value regarding the surface shape such as arithmetic average roughness Ra, but as described later, it is better to use the degree of gloss to feel the degree of matte tone visually perceived Can be represented.

  The degree of gloss required for the film is determined according to the application, and is preferably 90% or less in order to prevent the surface of the article to be molded from "shiny". Furthermore, in order to give a matte appearance to the surface of the article to be molded, the content is preferably 60% or less, more preferably 35% or less, and particularly preferably 30% or less.

  The tensile elongation of the film is preferably 5% or more, more preferably 10% or more, and particularly preferably 15% or more at normal temperature. The tensile elongation at normal temperature is particularly related to the handleability of the film. If the tensile elongation at normal temperature is too small, the film is likely to be damaged during handling. Therefore, for larger products, it is preferable to have greater tensile elongation.

  The tensile elongation of the film is preferably 40% or more, more preferably 60% or more, and particularly preferably 80% or more at 175 ° C. Furthermore, in each of the longitudinal direction (MD) and the transverse direction (TD), it is 40% or more, more preferably 60% or more, and particularly preferably 80% or more. If the tensile elongation at 175 ° C. is too small, the asperity of a mold or the like can not be sufficiently followed. As the unevenness of the mold or the like becomes deeper, the tensile elongation at 175 ° C. is required to be larger.

  The tensile elongation of the film can be determined by a tensile test. In the present specification, the tensile elongation refers to the elongation at break when a test piece having a shape defined in ASTM D 1708-6a is pulled at a speed of 200 mm / min.

  The wettability of the film is preferably 40 mN / m or less, more preferably 38 mN / m or less, and particularly preferably 35 mN / m or less. The low wettability of the film of the present embodiment is due to the characteristics of the SPS resin. The wettability of SPS resin is typically 32 to 33 mN / m. The wettability can be measured by the method defined in JIS K 6768: 1999.

  The heat shrinkage ratio is preferably 15% or less, more preferably 10% or less, and particularly preferably 8% or less at 175 ° C. The absolute value of the thermal contraction rate is preferably in the above-mentioned range in any of the MD direction and the TD direction. Moreover, the difference between the MD direction and the TD direction of the heat shrinkage does not pose a problem as long as the absolute value in each direction is in the above range, but the smaller the difference, the easier the condition setting of the molding process etc. Because it has the merits of The absolute value of the difference between the MD direction and the TD direction of the thermal shrinkage is more preferably 8% or less.

  In the present specification, the thermal shrinkage at 175 ° C. is the thermal shrinkage in each direction of MD and TD when the test piece (150 mm × 150 mm) is left at ambient temperature of 175 ° C. for 30 minutes. Is measured by the method described later. As for the value of thermal contraction rate, a positive value means contraction, and a negative value means expansion.

  Next, a method of manufacturing the film of the present embodiment will be described.

  The film of this embodiment is subjected to a biaxial stretching process on the obtained precursor film after the composition containing the above-mentioned resin is melted and kneaded to produce a precursor film (raw film before stretching). It can be manufactured by doing.

  A known method can be adopted as a method of producing the precursor film. For example, a mixture consisting of desired components may be melted and kneaded by an extruder, and the kneaded material may be extruded from a T-die and then cooled.

  The biaxial stretching step is a step of stretching in the biaxial direction of the film and then optionally heat setting. By this biaxial stretching step, the SPS-based resin is crystallized, the glass transition temperature of the film is increased, and the mechanical strength is improved. Moreover, the surface of the film of this embodiment is roughened by a biaxial stretching process.

  In biaxial stretching, stretching is performed in the MD direction and the TD direction of the film. The stretching method includes sequential biaxial stretching method and simultaneous biaxial stretching method, but it is preferable to use the simultaneous biaxial stretching method because the heat resistant dimensional stability and tensile elongation can be further improved. For example, according to the simultaneous biaxial stretching method, the difference between the MD direction and the TD direction of the absolute value of the thermal contraction rate can be easily made 8% or less. When performing biaxial stretching, the stretching ratio, the stretching temperature, and the stretching speed can be selected as appropriate conditions to obtain a desired coefficient of thermal expansion and the like.

  Heat setting is a process of fixing the orientation of polymer molecules by holding a stretched film at a temperature equal to or higher than the stretching temperature. The heat treatment temperature, time, relaxation ratio can be selected as appropriate conditions to obtain the desired thermal contraction rate and the like.

  In addition, in manufacture of the film of this embodiment, you may implement another roughening process after an extending process. For example, after the stretching step, the surface may be crimped to a engraved roll. Thereby, in addition to the surface asperity by biaxial stretching, larger asperity, for example, asperity giving larger Ra can be provided on the film surface.

  Hereinafter, the present invention will be more specifically described by way of examples.

  A full compound in which SPS alone or SPS and TPS were previously kneaded was melt-extruded at 280 ° C. using an extruder fitted with a T-die, and then cooled to obtain a precursor film. This precursor film was simultaneously biaxially stretched 3.4 times in the longitudinal direction (MD) and 3.4 times in the transverse direction (TD) at 110 ° C. at a stretching speed of about 500% / min. After stretching, the film was subjected to relaxation treatment at 210 ° C. in the longitudinal direction (MD) 0.95 times and in the transverse direction (TD) 0.95 times to obtain a simultaneous biaxially stretched SPS-based resin film having a thickness of about 50 μm. The glass transition temperature of the stretched film was 170 ° C. or more in all Comparative Examples and Examples.

Table 1 shows the production conditions and the gloss of the obtained film. The resins used are as follows.
-SPS: Brand name "Zarek 142 ZE", Idemitsu Kosan Co., Ltd. Glass transition temperature 95 ° C, melting point 247 ° C
· TPS (D): TPS-SEBS, trade name "Dynalon 8903P", JSR Corporation · TPS (T): TPS-SEBS, trade name "Tough Tech H1041", Asahi Kasei Corporation, TPS (S): TPS-SEEPS, Brand name "Septon 4055", Kuraray Co., Ltd.

  The appearance of the precursor film is visually confirmed, and those with no practical problems are shown as “○”, those with some defects are shown as “Δ”, and those with most defects are shown as “x”. The The glossiness of the film after stretching is a 60 degree specular gloss, Gs (60 °) as defined in JIS Z 874: 1997, and was measured using a gloss meter (UniGloss 60, Konica Minolta Co., Ltd.).

  In Examples 1 to 11 in which TPS is blended in SPS, the glossiness is smaller than Comparative Example 1 in which none of them contains TPS. In particular, in Examples 9 to 11 in which TPS-SEEPS was used as TPS, a remarkable decrease was observed in the glossiness, and it was confirmed that the gloss was remarkably small even by visual observation.

  Next, in Table 2, surface roughness and glossiness are shown for Comparative Example 1 and Examples 4 and 11. In the table, “unstretched film” is a precursor film before melting and stretching after melting and extrusion, “stretched film” is a film after stretching and heat setting, and “molded product” is an epoxy resin plate using a stretched film as a release film The product after heat-press molding, “film after molding” is a film after being used as the release film, and “film after heating at 175 ° C.” is a film after holding the film for 5 minutes at 175 ° C. It is data about,. The surface roughness is an arithmetic average roughness Ra, a maximum height Ry, a ten-point average roughness Rz, and an average interval Sm of irregularities as defined in JIS B 0601: 1994. The surface roughness was measured using a surface roughness measuring instrument (Handysurf, Tokyo Seimitsu Co., Ltd.).

In the evaluation, a hot press molded article of an epoxy resin plate was prepared as follows. As shown in FIG. 1, when the epoxy resin flakes 1 are heat-pressed with the upper and lower molds 2 and 3, the film 4 is interposed between the flakes 1 and the molds 2 and 3. The film 4 was gripped and fixed outside the mold. At the time of pressing, the approach of the molds 2 and 3 was restricted by the spacer 5. After press molding, the molded body was taken out, and the film 4 was immediately peeled off from the molded body. The press conditions were as follows: the temperature of the molds 2 and 3 was 175 ° C .; the press pressure was 100 kgf / cm ² ; the press clearance was 1 mm; and the press time was 3 minutes.

  It can be seen from Table 2 that the films of the examples maintain low gloss even after molding and after holding at 175 ° C. In addition, it can be seen that the degree of gloss of the molded product is also low, and the surface irregularities of the film are accurately transferred to the molded body.

  From Table 2, it is understood that Ra, Ry and Rz are larger and Sm is smaller in the film or the molded article of the embodiment having a low degree of gloss as compared with Comparative Example 1. However, the difference between the individual parameters is not very large. For example, Ra of the film of Example 11 is 0.17 μm, and the difference from Ra (0.1 μm) of the film of Comparative Example 1 is not very large. Therefore, it is not easy to determine the degree of matte tone using the measured value of surface roughness as an index. In addition, the degree of matte tone that can be visually recognized agrees well with the numerical value of glossiness. Therefore, as an index of the degree of roughening of the film of the embodiment, the glossiness is considered to be most suitable.

  Table 3 shows the wettability, heat shrinkage and tensile properties of the obtained film.

  In Table 3, the wettability was measured in accordance with JIS K 6768: 1999.

  The heat shrinkage was measured as follows. On a test piece (film; 150 mm × 150 mm), two straight lines with a length of 100 mm were drawn in parallel to the MD direction and the TD direction and at a midpoint of each other. The test piece was allowed to stand in a standard state (temperature 23 ° C. × humidity 50%) for 2 hours, and then the linear length before the test was measured. Subsequently, after leaving for 30 minutes in a suspended state with one corner supported in a hot air circulating oven set to an atmosphere of 175 ° C., it was taken out and allowed to stand and cooled in a standard state for 2 hours. Thereafter, the length of the straight line in each direction was measured, the amount of change from the length before the test was determined, and the thermal contraction rate was determined as a ratio of the amount of change to the length before the test.

  The tensile properties were measured as follows. Test pieces of a shape specified by ASTM D 1708-6a (gripping length is 16 mm) are prepared, and 200 mm / min using a tensile tester (Autograph “AG-10 kNIS MO”, Shimadzu Corporation) I went at speed. The test was performed 3 times for each of the MD direction and the TD direction, and the average was taken. The test at room temperature was conducted in a laboratory at room temperature of 23 ° C. The test at 175 ° C. was carried out in a constant temperature bath set at 175 ° C., and the test piece was held via an aluminum foil in order to prevent the film from sticking to the chuck (chuck) of the test apparatus. The tensile elongation is an elongation when a sample breaks.

  From Table 3, it can be seen that the flexibility of the film is improved by blending TPS. This is particularly preferable in the application as a release film, in order to accurately transfer the irregularities of the molding die surface to the material to be molded and to accurately transfer the matte tone of the film surface to the material to be molded.

  The present invention is not limited to the embodiments and examples described above, and various modifications are possible within the scope of the technical idea thereof.

  The roughened polystyrene-based film of the present invention is particularly useful as a release film at the time of molding, such as an epoxy resin printed substrate, but the application thereof is not limited thereto. The type of plastic constituting the material to be molded is not particularly limited. For example, it can be used to mold epoxy resin, phenol resin, melamine resin, urea resin, alkyd resin, polyimide resin, polyester resin, polyurethane resin, acrylic resin, etc. is there.

Claims (5)

Contains syndiotactic polystyrene based resins and styrenic thermoplastic elastomers,
The content ratio of the syndiotactic polystyrene-based resin to all polymer components is 50% by weight or more,
In all or part of the styrenic thermoplastic elastomer, the soft segment is composed of a poly (ethylene-ethylene / propylene) random copolymer block,
The weight ratio of the syndiotactic polystyrene resin (a) to the styrenic thermoplastic elastomer (d) having a poly (ethylene-ethylene / propylene) random copolymer block is (a) / (d) = 97 / 3-60 / 40,
Biaxially oriented,
Polystyrene-based release film having a rough surface. The glossiness is 90% or less,
A polystyrene-based release film having a rough surface according to claim 1. The tensile elongation at 175 ° C. is 40% or more in both the machine direction (MD) and the transverse direction (TD),
A polystyrene-based release film having a rough surface according to claim 1 or 2. The styrenic thermoplastic elastomer is a hydrogenated styrenic thermoplastic elastomer,
The polystyrene-type release film which has a rough surface as described in any one of Claims 1-3. Contains syndiotactic polystyrene based resins and styrenic thermoplastic elastomers ,
The content ratio of the syndiotactic polystyrene-based resin to all polymer components is 50% by weight or more,
In all or part of the styrenic thermoplastic elastomer, the soft segment comprises a poly (ethylene-ethylene / propylene) random copolymer block, and syndiotactic polystyrene-based resin (a) and poly (ethylene-ethylene / propylene) random a step of weight ratio of the styrene-based thermoplastic elastomer (d) to produce a (a) / (d) = 97 / 3~60 / 40 der Ru precursor film having a copolymerized block,
And a step of biaxially stretching the precursor membrane,
The manufacturing method of the polystyrene-type release film which has a rough surface.

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