JP2010082876A - Release paper for prepreg - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a release paper for prepregs having excellent dimensional stability and stiffness and being reusable. <P>SOLUTION: The release paper for prepreg is obtained by piling up a heat-curable silicone layer (I) 140, a polyolefin based resin layer (I) 120, a paper substrate 110, and a polyolefin based resin layer (II) 120' in this order. A heat-curable silicone layer (II) may be piled up on the polyolefin based resin layer (II). Stiffness can be inexpensively ensured and the release paper can be reused, reducing the waste of the release paper after use. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a release paper for prepreg, and more particularly to a release paper for prepreg which is excellent in moisture resistance and dimensional stability.

  For materials in fields such as golf shafts, fishing rods, tennis rackets, ski stocks, car parts, bicycle bodies, leisure sports equipment, aircraft, space and military related fields, carbon fiber reinforced carbon fiber impregnated with epoxy resin A carbon fiber prepreg in which a resin is detachably bonded to a release paper is used.

  Such a carbon fiber prepreg is obtained by applying an epoxy resin laminated release paper in which a heat-melted epoxy resin is applied to a release paper for prepreg with a certain thickness, and this is cooled to laminate a semi-cured epoxy resin layer. Manufactured using. Specifically, an epoxy resin is laminated on a prepreg release paper in advance to prepare an epoxy resin laminate release paper, two sheets of this epoxy resin laminate release paper are prepared, and as shown in FIG. The epoxy resin layers (13) and (13 ′) of the resin laminate release paper (10) and (10 ′) are arranged to face each other, and the carbon fiber (20) is put between them. When the temperature of the epoxy resin layers (13) and (13 ′) is increased by the heater (30), the carbon fibers (20) are impregnated with the epoxy resins (13) and (13 ′), and the carbon fibers (20) and the epoxy are injected. A carbon fiber-impregnated epoxy resin layer (25) in which the resins (13) and (13 ′) are integrated is formed. Next, when a protective film (40) such as a polyethylene film is laminated on the surface of the carbon fiber-impregnated epoxy resin layer (25) on the release paper (11) for prepreg, a carbon fiber prepreg is obtained. The prepreg for carbon fiber is taken up by a product take-up roll (50), and the release paper for prepreg (11 ') removed in the production process is taken up by a release paper collecting roll (60).

  The prepreg for carbon fiber thus obtained maintains the carbon fiber-impregnated epoxy resin layer (25) between the release paper for prepreg (11) and the protective film (40) in an uncrosslinked state. Stored in low temperature conditions. In use, the protective film (40) and the prepreg release paper (11) are removed from the plate-like or fabric-like carbon fiber prepreg, and an uncrosslinked carbon fiber-impregnated epoxy resin layer (25) is laminated to a predetermined thickness. Then, it can be heat-molded and formed into various shapes to produce a carbon product.

  On the other hand, when laminating the carbon fiber-impregnated epoxy resin layer (25), if air enters between the carbon fiber-impregnated epoxy resin layers (25), voids are formed, and the layer structure is destroyed, so the impact strength is reduced. There is. Such a disorder in the layer structure also occurs when the carbon fiber impregnated epoxy resin layer (25) is laminated in a slack state in addition to the gaps between the layers. For example, when the prepreg release paper (11) constituting the carbon fiber prepreg shrinks, peeling occurs between the prepreg release paper (11) and the carbon fiber-impregnated epoxy resin layer (25). The fiber-impregnated epoxy resin layer (25) may not be uniformly laminated, and disorder may occur between the layers. As described above, the carbon fiber prepreg is heated when the epoxy resin (13) or (13 ') is impregnated with the carbon fiber (20), and cooled to such an extent that uncrosslinked can be maintained during storage. For this reason, the release paper for prepreg needs to be excellent in dimensional stability even under such a large temperature change environment. Currently, aircraft wings are manufactured from carbon fiber prepregs using the toughness of carbon fibers, but aircraft require a high level of safety. Therefore, release paper for prepregs that constitutes carbon fiber prepregs. In addition, a high degree of dimensional stability is required.

As such a release paper having excellent dimensional stability, it is a process paper for prepreg in which at least one side of a base paper having a moisture-proof layer on both sides is subjected to a release treatment, and the moisture permeability measured in accordance with JIS Z 0208 is 200 g. There is also a process paper for prepreg characterized by being / m ² · 24 hours or less (Patent Document 1). Due to changes in humidity and temperature in the storage atmosphere, the process paper was partially peeled off from the prepreg, resulting in irregularities on the prepreg surface, and wrinkles and voids due to the irregularities on the molded body. By suppressing the change in moisture content of the process paper, it is possible to prevent the process paper from being lifted off from the prepreg, and to provide a high-quality prepreg material that does not cause unevenness on the prepreg surface.

  Further, a base paper made of wood pulp having a standard freeness of Canada in a predetermined range was provided with a sealing layer made of a pigment and a binder on a base paper made by impregnating an acrylic resin having a glass transition temperature of 20 ° C to 100 ° C. A base paper for processing, wherein the binder is a latex having a gel content of 80% by mass or more, and the mass ratio of the pigment and latex in the filler layer is 100/45 to 100/15. There is also a processing base paper (Patent Document 2). In addition to being excellent in dimensional stability and sealing agent release properties, a processing base paper that can be recycled as a papermaking raw material is provided.

Furthermore, a base paper mainly composed of wood pulp is coated or impregnated with water-resistant polyvinyl alcohol treated with a water-resistant agent, heated at 110 ° C. for 2 hours, and then at 23 ° C. and a relative humidity of 50%. There is also a process release paper base paper characterized in that the elongation in the width direction after being left for 60 minutes is 1.0% or less (Patent Document 3). In the prepreg manufacturing process, the release paper for the intermediate process shrinks due to moisture reduction in the paper due to heating, and absorbs moisture in the air in the subsequent cooling process, and this expansion and contraction causes the carbon fiber reinforced resin and the release paper to It is made in view of the problem that peeling occurs between them, and even if moisture is absorbed by cooling after heating, the elongation is reduced until a certain time elapses during cooling, and the carbon fiber reinforced resin and the release paper It is said that it can eliminate the peeling and deformation.
JP 2005-220482 A JP 2006-274483 A JP 2007-009348 A

  As described above, the prepreg release paper is required to have a high degree of dimensional stability. Patent Document 1 defines the smoothness and moisture permeability of the surface of the paper substrate constituting the release paper. Patent Document 2 uses a base paper made of wood pulp having a Canadian standard freeness within a predetermined range. In No. 3, by restricting the elongation rate of the release paper, the dimensional stability of the release paper for prepreg is ensured and partial peeling of the prepreg is prevented. However, the paper base material used for such release paper is expensive. As shown in FIG. 4, since the prepreg is manufactured using two epoxy resin laminated release papers (10) and (10 ′), a prepreg release paper twice as long as the prepreg is used. That is, the paper substrate used for the prepreg release paper also needs to be twice as long as the prepreg. Therefore, it is desired to develop a release paper for prepreg that uses an inexpensive paper base and is excellent in dimensional stability.

  Moreover, the release paper used for the carbon fiber prepreg is generally discarded after it is once used as the release paper for prepreg. As described above, release paper twice as long as the prepreg is used, and all of the release paper is discarded after use of the prepreg, so that a predetermined time and labor are imposed on the disposal process. Therefore, it is preferable that the prepreg release paper once used can be reused, but the conventional prepreg release paper lacks rigidity and may have poor shape retention. For this reason, it is desired to develop a release paper for prepreg that can secure a predetermined rigidity and can be reused and has excellent strength.

  Furthermore, the release paper for prepreg is required to have excellent peelability as well as dimensional stability. In the above Patent Documents 1 to 3, a silicone resin or the like is used as a release layer, and it is necessary to ensure adhesion between the paper base material layer and the silicone resin layer. In Patent Document 2, a predetermined sealing layer is laminated, and in Patent Document 3, polyvinyl alcohol is impregnated. However, development of a release paper for prepreg that is inexpensive and excellent in peelability is desired.

  As a result of examining the release paper for carbon fiber prepreg in detail, the present inventor found that the dimensional change of the release paper for prepreg was caused by dehydration of the paper substrate in the temperature rising process when carbon fiber was impregnated with epoxy resin, and the temperature was lowered. If the maintained carbon fiber prepreg is caused by water absorption when it is used at room temperature, and therefore dehydration and water absorption due to such temperature changes can be prevented, the conventional prepreg release paper can be used using a low-cost clay-coated paper. That it can be manufactured, that the dimensional change can be prevented by laminating a polyolefin resin layer on both sides of a paper base material, and that a release paper for prepreg that is excellent in releasability when a thermosetting silicone layer is laminated on the polyolefin resin layer is produced. As a result, the present invention has been completed.

The release paper for prepreg of the present invention can be produced using an inexpensive paper base material, and is economical.
The release paper for prepreg of the present invention exhibits an excellent moisture-proof effect only by laminating a polyolefin resin layer, and thus a release paper for prepreg having excellent dimensional stability can be easily produced.

  The first of the present invention is a release paper for prepreg, characterized in that a thermosetting silicone layer (I), a polyolefin resin layer (I), a paper base material, and a polyolefin resin layer (II) are laminated in this order. It is. Moisture resistance, dimensional stability and rigidity are imparted by forming a polyolefin-based resin layer on a paper substrate, and peelability can be imparted by further laminating a thermosetting silicone layer. The present invention will be described in detail with reference to FIG. 1 showing an example of a preferred embodiment of the present invention.

(1) Release paper for prepreg The release paper for prepreg of the present invention comprises a thermosetting silicone layer (I) (140), a polyolefin resin layer (I) (120), a paper substrate (110) as shown in FIG. ) And polyolefin resin layer (II) (120 ′) are laminated in this order. By laminating an epoxy resin layer on the thermosetting silicone layer (I) (140), it can be used as an epoxy resin laminate release paper.

  On the other hand, as shown in FIG. 2, a thermosetting silicone layer (II) (140 ') may be laminated after the polyolefin resin layer (II) (120'). The release paper for prepreg is laminated with an epoxy resin on one side to become an epoxy resin laminate release paper, and is wound into a roll when storing a long epoxy resin laminate release paper. Therefore, if it is a double-sided release paper in which the thermosetting silicone layer (I) (140) and the thermosetting silicone layer (II) (140 ′) are respectively laminated on both surfaces of the outermost layer of the paper base material, Smooth pull-out of the epoxy resin laminated release paper can be ensured. At this time, the peel strength between the thermosetting silicone layer (I) and the thermosetting silicone layer (II) may be different. When an epoxy resin layer is laminated on a surface with low peel strength and wound into a roll, the adhesion between the release paper and the epoxy resin layer can be secured and the epoxy resin laminate release paper can be easily pulled out of the roll. .

(2) Paper base material The paper base material used in the present invention can withstand the process of laminating the polyolefin resin layer (120) and the thermosetting silicone layer (140), and the heating temperature for impregnating the carbon fiber with the epoxy resin. Can be used widely. In addition to non-coated paper such as kraft paper, high-quality paper, single gloss kraft paper, pure white roll paper, glassine paper, and cup base paper, synthetic paper that does not use natural pulp can also be used. As described above, since the polyolefin resin layer (I) and the polyolefin resin layer (II) are laminated to prevent dehydration and water absorption and have excellent dimensional stability, paper made of natural pulp is preferably used. Can do.

In the present invention, the paper used as a paper substrate weighing 50 to 300 g / m ^2, preferably 100 to 200 g / m ^2. If it is this range, a polyolefin-type resin layer and a thermosetting silicone layer can be laminated | stacked, and the release paper which has the intensity | strength suitable for reuse can be manufactured. The paper is preferably neutral paper. When acid paper containing a sulfuric acid band or the like is used repeatedly, thermal degradation occurs, and it may be difficult to reuse it early. If it is a neutral paper, such thermal deterioration can be prevented.

  The paper used in the present invention may use neutral rosin, alkyl ketene dimer, alkenyl succinic anhydride as a sizing agent, and use cationic polyacrylamide or cationic starch as a fixing agent. Also good. Moreover, although it is most preferable not to use a sulfuric acid band for the said reason, it is also possible to make paper in a neutral region of pH 6-9 using a sulfuric acid band. In addition to the above sizing agents, as well as fixing agents, various papermaking fillers, yield improvers, dry paper strength enhancers, wet paper strength enhancers, binders, dispersants, flocculants, plastics An agent and an adhesive may be appropriately contained.

  Furthermore, as the paper base material used in the present invention, for example, general, such as clay-coated paper, fine-coated printing paper, coated printing paper, resin-coated paper, processed base paper, release base paper, double-side coat release base paper, etc. A commercial product in which a sealing layer to be described later is formed can also be used.

(3) Polyolefin-based resin layer The polyolefin-based resin layer is a layer formed between the paper substrate and the thermosetting silicone layer (I), and is not limited to a single layer but may be a multilayer of two or more layers. . Moreover, the mixture layer of polyolefin resin and an inorganic pigment may be sufficient.

(I) Polyolefin resin Examples of the polyolefin resin that can be used include polyolefin resins such as polyethylene, polypropylene, and polymethylpentene resins. Among these, polypropylene resins and polymethylpentene resins are preferable in terms of excellent heat resistance and workability.

  The propylene-based resin used in the present invention is not limited to a propylene homopolymer as long as it does not impair the heat resistance as a release paper for prepreg, and is mainly composed of propylene and, for example, ethylene, butene, pentene, hexene, octene. And a copolymer with an α-olefin such as 4-polymethylpentene-1.

  The polymethylpentene-based resin is a polymer mainly composed of 4-methyl-1-pentene. In addition to a homopolymer of 4-methyl-1-pentene, 4-methyl-1-pentene and other α A copolymer with an α-olefin having 2 to 20 carbon atoms such as ethylene, propylene, 1-butene, 1-hexene, 1-octene, 1-decene, 1-tetradecene, 1-octadecene, etc. May be. The polymethylpentene resin is particularly preferable because it has a melting point of 230 to 240 ° C. and excellent heat resistance.

  As described above, the polyolefin resin layer is not limited to a single layer. For example, a first polyolefin resin layer (120A, 120A ′) selected from a polypropylene resin and a polymethylpentene resin, and a composition comprising a resin and a polyethylene resin constituting the first polyolefin resin layer. Two polyolefin resin layers (120B, 120B ′) and a third polyolefin resin layer (120C, 120c ′) made of polymethylpentene resin may be laminated. This embodiment is shown in FIG. At this time, in the second polyolefin resin layer (120B, 120B '), the blending amount of the polyethylene resin is 5 to 80 mass%, more preferably 10 to 50 mass%. Polyethylene has a lower melting point than polypropylene resin or polymethylpentene resin, but the first polyolefin resin layer is formed by laminating a polymethylpentene resin layer as the third polyolefin resin layer (120C, 120c ′). This is because (120A) and the paper substrate (110) can be suitably bonded, and the heat resistance when impregnated with the epoxy resin can be ensured. In addition, there is no restriction | limiting in particular as polyethylene-type resin to be used, Any of low density polyethylene, medium density polyethylene, and high density polyethylene may be sufficient. However, since the melting point differs depending on the density, the melting point is preferably 90 to 130 ° C, more preferably 110 to 120 ° C.

  The polyolefin resin layer can be prepared by laminating the polyolefin resin on a paper substrate by roll coating, gravure coating, extrusion coating, knife coating, Miya bar coating, dip coating, or the like. In addition, when a polyolefin resin layer is a multilayer, you may laminate | stack on a paper base material by coextrusion etc.

  The thickness of the polyolefin resin layer is preferably 3 to 40 μm, more preferably 5 to 20 μm. If it is thinner than 3 μm, the adhesiveness to the paper substrate may be lowered, while if it exceeds 40 μm, the curl of the release paper may be increased.

  In the present invention, the polyolefin resin layer is preferably subjected to a surface treatment. Such surface treatment can improve the adhesion between the polyolefin resin layer and the thermosetting silicone layer. Such surface treatment includes flame treatment, corona discharge treatment, ozone treatment, low temperature plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, oxidation treatment using chemicals, etc. There is processing. In addition, a primer coating agent, an undercoat agent, an anchor coating agent, an adhesive, a vapor deposition anchor coating agent, or the like can be optionally applied in advance and surface-treated. Examples of the coating agent include polyester resins, polyamide resins, polyurethane resins, epoxy resins, phenol resins, (meth) acrylic resins, polyvinyl acetate resins, polyolefins such as polyethylene or polypropylene. A resin composition containing a resin or a copolymer or modified resin thereof, a cellulose resin, or the like as a main component of the vehicle can be used.

  Among such surface treatments, it is particularly preferable to perform corona treatment or plasma treatment. Moreover, as plasma processing, there is plasma processing in which surface modification is performed using plasma gas generated by ionizing gas by arc discharge. In addition to the above, an inorganic gas such as oxygen gas, nitrogen gas, argon gas, helium gas can be used as the plasma gas. Furthermore, in the present invention, it is preferable to perform the plasma discharge treatment in consideration of the plasma output, the kind of plasma gas, the supply amount of the plasma gas, the treatment time, and other conditions. Moreover, as a method for generating plasma, DC glow discharge, high frequency discharge, microwave discharge, and other devices can be used. In addition, plasma treatment can be performed by an atmospheric pressure plasma treatment method.

(Ii) Mixture layer with inorganic pigment As the mixture layer, a layer containing 0.5 to 50% by mass of an inorganic pigment with respect to the polyolefin resin can be suitably used.

Examples of the inorganic pigment include talc, kaolin clay, silica, calcium carbonate, barium sulfate, titanium oxide, and zinc oxide, and 20 to 30 parts by mass of the polyolefin-based resin is blended with 100 parts by mass of the inorganic pigment. If the polyolefin-based resin exceeds 30 parts by mass, the sealing effect, moisture-proofing effect, and dimensional stability may be reduced. On the other hand, if the polyolefin-based resin is less than 20 parts by mass, the effect of addition may inhibit smoothness. Such a mixture layer can be applied to a paper substrate and used as a sealing layer when the polyolefin-based resin is composed of multiple layers. At this time, the coating amount of the polyolefin resin is preferably 0.5 to 20 g / m ² . The coating of the mixture layer can be applied by diluting with a solvent of usually 10 to 1000 parts by mass with respect to 100 parts by mass of the solid content. By diluting the solvent, an appropriate viscosity for coating, for example, a viscosity of 10 to 3000 mPa · sec at 25 ° C. can be imparted.

  In addition, after forming a mixture layer on a paper base material, you may smooth | blunt by performing a calendar process etc. Next, the first polyolefin resin layer, the second polyolefin resin layer, and the third polyolefin resin layer described above may be laminated.

(4) Thermosetting silicone layer The thermosetting silicone layer used in the present invention is formed by thermosetting a thermosetting silicone composition comprising an alkenyl group-containing organopolysiloxane, an organohydrogenpolysiloxane and a platinum-based curing catalyst. Can be preferably used.

  Examples of the alkenyl group-containing organopolysiloxane include the following compounds.

（上記式中におけるＲは主としてメチル基であるが、その他のアルキル基またはフェニル基等のアリール基或はそれらの組み合わせで有り、ｌ＋ｍ＋ｎは１以上の整数であり、各シロキサン単位はランダムに配置されていてもよい。Ｘ、ＹおよびＺのうち少なくとも１個はビニル基、アリル（−ＣＨ₂−ＣＨ＝ＣＨ₂）基または（メタ）アクリロイル基等に付加重合性基であり、Ｒ¹〜Ｒ³は単結合或はアルキレン基である。）
以上のアルケニル基含有オルガノポリシロキサンの分子量は特に限定されないが、一般的には３，５００〜２０，０００の範囲が好適である。これらのアルケニル基含有オルガノポリシロキサンは市場から入手でき本発明で容易に使用することができる。

(In the above formula, R is mainly a methyl group, but is an aryl group such as other alkyl group or phenyl group or a combination thereof, and l + m + n is an integer of 1 or more, and each siloxane unit is randomly arranged. At least one of X, Y and Z is an addition polymerizable group such as a vinyl group, an allyl (—CH ₂ —CH═CH ₂ ) group or a (meth) acryloyl group, and R ^{1 to} R ³ is a single bond or an alkylene group.)
The molecular weight of the above alkenyl group-containing organopolysiloxane is not particularly limited, but is generally in the range of 3,500 to 20,000. These alkenyl group-containing organopolysiloxanes are commercially available and can be easily used in the present invention.

Organohydrogenpolysiloxane used in the present invention are those -R ¹ -X, at least one of -R ² -Z, and -R ³ -Y in the general formula is a hydrogen atom, the other The substituent, the arrangement of siloxane units, the molecular weight and the like are the same as in the general formula. These alkenyl group-containing organopolysiloxanes are commercially available and can be easily used in the present invention.

  The proportion of the alkenyl group-containing organopolysiloxane and the organohydrogenpolysiloxane is determined by the molar ratio of the reactive groups of the both, and the ratio of the former to the latter is 4: 1 to 1: 4, particularly 1: 1 to 1. : 3 is preferred, and if it is outside this range, satisfactory performance cannot be obtained in terms of reduction in releasability, reduction in coating film strength, deterioration in storage stability due to unreacted reactive groups, and the like.

  In the present invention, a platinum-based curing catalyst is further used. The catalyst is preferably used in an amount of about 5 to 200 parts by mass per 100 parts by mass of the alkenyl group-containing organopolysiloxane and organohydrogenpolysiloxane.

  The thermosetting silicone composition composed of the above alkenyl group-containing organopolysiloxane, organohydrogenpolysiloxane, and platinum-based curing catalyst, the reaction proceeds even at room temperature, and the progress of the reaction in the coating solution is degraded. In addition, a problem arises in the storage and handling properties of the coating liquid. In the present invention, in order to solve such a problem, a reaction inhibitor that has a reaction suppressing effect on the thermosetting silicone composition at normal temperature and that eliminates the suppressing effect at the time of heat treatment may be used. Specifically, the reaction inhibitor used in the present invention, in the state of the solvent solution, suppresses the action of the curing catalyst on the thermosetting silicone composition described above, the heated state and the state where the solvent is volatilized, That is, it is a material that does not suppress the action of the curing catalyst in the heated or dried state, but rather promotes it. Examples of such a curing inhibitor include silylated products of acetylene alcohol. These reaction inhibitors can be obtained from the market and used. Such a reaction inhibitor is preferably used at a ratio of about 5 to 100 parts by mass per 100 parts by mass of the thermosetting silicone composition.

  As such a thermosetting silicone composition, a commercially available product may be used. For example, a main component of an addition polymerization type silicone material (Shin-Etsu Chemical Co., Ltd.) composed of a mixture of an alkenyl group-containing organopolysiloxane and an organohydrogenpolysiloxane. It can be prepared by mixing a curing agent comprising a platinum-based curing catalyst (CAT-PL-50T, manufactured by Shin-Etsu Chemical Co., Ltd.) with KS-3603) manufactured by Kogyo Co., Ltd.

The thermosetting silicone composition is a material that is in a solid state at room temperature but changes to a liquid state by heating during processing.
The thermosetting silicone composition of the present invention needs curability to obtain sufficient film properties such as strength.

  The method of forming the thermosetting silicone layer of the present invention itself may be the same as the formation of the dye-receiving layer such as application of the thermosetting silicone composition, drying and heating, and aging, and the thickness of the thermosetting silicone layer to be formed is A range of 0.01 to 10 μm is preferable.

  As described above, when the release paper for prepreg of the present invention has the thermosetting silicone layer (I) and the thermosetting silicone layer (II), these peel strengths are preferably different. Thermosetting silicone resins are manufactured in advance by changing the molecular weight of the alkenyl group-containing organopolysiloxane or organohydrogenpolysiloxane, the type of substituent, the proportion of alkenyl group-containing organopolysiloxane and organohydrogenpolysiloxane used, etc. By determining the peel strength, a thermosetting silicone layer having a different peel strength can be laminated.

(5) Manufacturing method of release paper for prepreg The release paper for prepreg of the present invention can be manufactured by laminating a polyolefin resin layer and a thermosetting silicone layer on a paper substrate.

  For example, the polyolefin resin layers (120) and (120 ′) are laminated on both sides of the paper substrate (110), and then, for example, corona treatment is performed on both the polyolefin resin layers (120). Surface treatment is performed to form a surface treatment layer. Next, a thermosetting silicone composition is applied on at least one polyolefin resin layer, and is dried by heating to form a thermosetting silicone film.

  In addition, it is preferable that the thickness of the release paper for prepregs of this invention is 50-300 micrometers, More preferably, it is 70-150 micrometers. When the thickness is less than 50 μm, the strength is lowered, and line suitability such as easy cutting during winding in the production process may be lowered. On the other hand, if it exceeds 300 μm, the width curl of the release paper for prepreg becomes large, and the workability may be lowered.

(6) Carbon fiber prepreg Using the release paper for prepreg of the present invention, a carbon fiber prepreg can be produced by the method illustrated in FIG. The carbon fiber prepreg using the release paper for prepreg of the present invention is excellent in dimensional stability and is kept between the carbon fiber-impregnated epoxy resin layer and the release paper even when stored at a low temperature in order to keep the epoxy resin uncrosslinked. No peeling occurs. In addition, the carbon fiber impregnated epoxy resin layer does not sag when the carbon fiber impregnated epoxy resin layer is laminated, and the carbon fiber impregnated epoxy resin layer does not generate unevenness or voids due to partial overlap of the carbon fiber impregnated epoxy resin layer. Can be manufactured.

  Moreover, peeling between the paper substrate and the polyolefin resin layer is prevented, the presence of a polyolefin resin layer having excellent heat resistance, dimensional stability and high mechanical strength, and a thermosetting silicone layer excellent in peelability. Stable peelability is maintained by the presence.

Next, the present invention will be described in more detail by showing specific examples.
(Experimental example 1)
Polypropylene (Sun Allomer, Sun Allomer PHA03A, melting point 163 ° C.) was coated on both sides of high quality paper (basis weight 104.5 g / m ² ) by 5 μm by tandem type extrusion coating. Next, after corona treatment is performed on only one surface to improve the wettability of the surface, 100 parts by mass of an addition polymerization type silicone resin (trade name “KS-3603” manufactured by Shin-Etsu Chemical Co., Ltd.), a release control agent, and the product name “KS” -3800 "mixture of 2 parts by mass) was 0.3 g / m ² coating was prepared a prepreg for release paper having a release layer on one side.

Next, bisphenol A type epoxy resin (40 parts by mass of JER828 made by Japan Epoxy Resin and 50 parts by mass of JER1001 made by Japan Epoxy Resin) and 5 parts by mass of dicyandiamide (DICY7 made by Japan Epoxy Resin) were added to the obtained release paper for prepreg. -5 parts by mass of (3,4-dichlorophenyl) -1,1-dimethylurea (Hodogaya Chemical Industrial DCMU-99) was dissolved by stirring in a warm bath at 70 ° C for 30 minutes, and the step was carried out at about 65 ° C. About 40 g / m ² was applied to the paper, carbon fibers were pasted, and nip was repeated four times with a nip roll at a temperature of 125 ° C. and 0.75 MPa to obtain an epoxy resin layer laminated release paper.

Repeated peelability evaluation and appearance observation for repeated use of this epoxy resin layered release paper were evaluated, and the dimensional change rate was also evaluated. The results are shown in Tables 1 and 2.
The repeated peelability evaluation was performed by observing whether or not the epoxy resin layer and the prepreg release paper were in close contact with each other in the epoxy resin layer laminated release paper.

Appearance observation evaluated the change of the external appearance of the epoxy resin layer laminated release paper.
Further, the change in dimensions was evaluated by the percentage change in dimension in the longitudinal direction of the original fabric in the longitudinal direction of the original fabric after being dried at 110 ° C. for 2 hours and then left at 23 ° C. and 50% Rh for 3 hours.

(Comparative Example 1)
Polypropylene (Sun Allomer, Sun Allomer PHA03A, melting point 163 ° C.) was coated to 5 μm on one side of high quality paper (basis weight 104.5 g / m ² ). Next, the polypropylene layer is subjected to corona treatment to improve the wettability of the surface, and then 100 parts by mass of an addition polymerization type silicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., trade name “KS-3603”), a release control agent, and a trade name A prepreg release paper having 0.3 g / m ^{2 of} “KS-3800” (mixture of 2 parts by mass) and having a release layer on one side was produced.

  Using this prepreg release paper, an epoxy resin layered release paper was prepared in the same manner as in Example 1. Similar to Experimental Example 1, repeated peelability evaluation and appearance observation for repeated use of the epoxy resin layered release paper In addition, the rate of change in dimensions was evaluated. The results are shown in Tables 1 and 2.

FIG. 1 shows a release paper for prepreg according to the present invention, in which a thermosetting silicone layer (I), a polyolefin resin layer (I), a paper substrate, and a polyolefin resin layer (II) are laminated in this order. It is a figure explaining the laminated structure of. FIG. 2 is a view for explaining the laminated structure of the release paper for prepreg of the present invention, in which the thermosetting silicone layer (II) is laminated after the polyolefin resin layer (II) of FIG. FIG. 3 is a view for explaining a laminated structure of the release paper for prepreg of the present invention, in which the polyolefin resin layer (I) and the polyolefin resin layer (II) in FIG. 1 are composed of two layers. It is explanatory drawing which shows the manufacturing method of the carbon fiber prepreg using the release paper for prepregs by this invention.

Explanation of symbols

10, 10 '... epoxy resin laminate release paper,
11, 11 '... release paper,
13, 13 '... epoxy resin layer,
20 ... carbon fiber,
25 ... a carbon fiber impregnated epoxy resin layer,
30 ... heater,
40 ... Protective film,
50 ... Product take-up roll,
60 ... release paper collection roll,
110 ... paper substrate,
120, 120 '... polyolefin resin layer,
120A, 120A ′, 120B, 120B ′, 120C, 120C ′... Polyolefin resin layer,
140, 140 '... thermosetting silicone layer.

Claims (6)

  A release paper for prepreg, wherein a thermosetting silicone layer (I), a polyolefin resin layer (I), a paper base material, and a polyolefin resin layer (II) are laminated in this order.   A release paper for prepreg, wherein a thermosetting silicone layer (II) is laminated next to the polyolefin resin layer (II).   The release paper for prepreg according to claim 2, wherein the thermosetting silicone layer (I) and the thermosetting silicone layer (II) have different peel strengths.   The release paper for prepreg according to any one of claims 1 to 3, wherein the thermosetting silicone layer (I) and / or the thermosetting silicone layer (II) comprises an addition polymerization type silicone resin.   The thermosetting silicone layer (I) and / or the thermosetting silicone layer (II) is obtained by thermosetting a thermosetting silicone composition comprising an alkenyl group-containing organopolysiloxane, an organohydrogenpolysiloxane and a platinum-based curing catalyst. The release paper for prepreg according to any one of claims 1 to 4, which is formed.   The prepreg according to claim 1, wherein the polyolefin resin layer (I) and / or the polyolefin resin layer (II) is a mixture layer of a polyolefin resin and an inorganic pigment. Release paper.

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