JP2010126683A - Method for manufacturing prepreg sheet, and laminated plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a prepreg sheet, by which a high quality prepreg sheet can easily be manufactured. <P>SOLUTION: The method for manufacturing a prepreg sheet includes: a coating process for coating a releasing sheet 2 with a resin composition 6 containing a curing agent and an inorganic filling material together with a thermosetting resin 22 dissolved in a solvent; a heating process for heating the resin composition 6 coated on the releasing sheet 2 to evaporate the solvent in the resin composition 6 and to bring the thermosetting resin into a B-stage; and a pressurizing process for pressing the thermosetting resin 22 in the B-stage to the both surfaces of a sheet-like base material to impregnate the base material with at least a portion of the thermosetting resin 22. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for producing a prepreg sheet and a laminate.

  Conventionally, a laminated board used for a printed wiring board or the like is formed by stacking a plurality of prepreg sheets and applying heat and pressure. As a conventional method for producing a prepreg sheet, it is known to impregnate a base material with a low-viscosity epoxy resin varnish diluted with a solvent, and then heat and evaporate the solvent (for example, Patent Document 1).

  However, in this production method, adjustment of the thickness of the prepreg (resin content) is performed exclusively by adjusting the viscosity of the varnish, so that a large amount of solvent is required, increasing the environmental and economic burden. There was a problem.

  On the other hand, in Patent Document 2, after a raw material resin made of a thermosetting resin containing a curing agent or the like is mixed by a static mixer, the mixed resin is applied to a release paper, and this release paper is used as a reinforcing fiber material. A manufacturing method of a prepreg is disclosed in which a mixed resin on a release paper is transferred to and impregnated into a reinforcing fiber material by superimposing on both sides, heating and pressurizing, and a manufacturing method using a solventless raw material is also known. .

However, the manufacturing method of Patent Document 2 has room for further improvement from the viewpoint that uniform mixing of the mixed resin and temperature control when the mixed resin is applied to the release paper tend to be difficult, and production efficiency is increased.
JP-A-4-103306 JP-A-8-267449

  Then, this invention aims at provision of the manufacturing method of the prepreg sheet | seat which can manufacture a high quality prepreg sheet | seat easily.

  The object of the present invention is to apply a resin composition containing a curing agent and an inorganic filler together with a thermosetting resin dissolved in a solvent to a release sheet, and to heat the resin composition applied to the release sheet. By evaporating the solvent in the resin composition and heating the thermosetting resin to the B stage state, and pressing the B stage thermosetting resin on both sides of the sheet-like substrate And a pressurizing step of impregnating the base material with at least a part of the thermosetting resin.

  In this prepreg sheet manufacturing method, the coating step may include a step of making the thickness of the resin composition applied to the release sheet constant with a blade so that a desired resin thickness is obtained after the heating step. preferable.

  Moreover, it is preferable to raise the heating temperature of the resin composition to a temperature higher than the boiling point of the solvent after temporarily maintaining the heating temperature of the resin composition at a temperature higher than normal temperature and lower than the boiling point of the solvent.

  A plurality of prepreg sheets obtained by the above-described method for producing a prepreg sheet can be laminated, and a laminate can be obtained by heating and pressing under vacuum.

  According to the method for producing a prepreg sheet of the present invention, a high-quality prepreg sheet can be easily produced.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a process diagram for explaining a method for producing a prepreg sheet according to an embodiment of the present invention.

  As shown in FIG. 1, the resin composition 6 supplied to the surface of the release sheet 2 fed out from a roll (not shown) is formed between the release sheet 2 and the blade 4 as the release sheet 2 advances. The coating process is performed by passing through the gap formed therebetween and adjusting to a predetermined constant thickness.

  The resin composition 6 is liquid at room temperature in which a thermosetting resin is dissolved in a solvent such as methyl ethyl ketone (MEK), cyclohexanone, or xylene. Examples of the thermosetting resin include an epoxy resin, an acrylic resin, a polyimide resin, a silicone resin, and a phenol resin, and an epoxy resin can be particularly preferably used. When the thermosetting resin is an epoxy resin, a bisphenol type, a phenol novolac type, a cresol novolak type, a biphenyl type, a naphthalene type, or the like can be used, and a solid that is dissolved at room temperature can be used. Furthermore, what melt | dissolved normal temperature solid epoxy resin in the solvent and normal temperature liquid epoxy resin may be mixed, and what improved the brittleness in the B-stage state mentioned later may be used. It is also possible to combine an epoxy resin having a rigid skeleton in order to improve the glass transition temperature (Tg) and heat resistance.

  From the viewpoint of suppressing the amount of solvent used, it is preferable to reduce the blending ratio of the solvent as much as possible within the range in which the thermosetting resin is surely dissolved. It is preferable to set the split to 5 to 20% by weight.

  Moreover, the resin composition 6 contains a hardening | curing agent and an inorganic filler. Examples of the curing agent for the epoxy resin include dicyandiamide, phenol novolac, cresol novolac, and the like. Moreover, an imidazole compound etc. can be used as a hardening accelerator. The curing agent may be either a dispersion type or a dissolution type.

  Inorganic fillers are for improving properties such as strength improvement after curing, reduction of thermal expansion, and improvement of thermal conductivity. For example, silica particles are mixed to lower the coefficient of linear expansion, alumina, metal, etc. It is possible to increase the thermal conductivity by blending these nitrides. Alternatively, for the purpose of flame retardancy, fine particles (average particle size 2 to 30 μm) such as aluminum hydroxide and magnesium hydroxide can be blended in an amount of about 50 to 80% by weight with respect to the entire resin composition 6. Yes, even if the base material impregnated with the resin composition 6 is paper, good flame retardancy can be obtained. These inorganic fillers may be used alone or in combination of two or more.

  The method for producing a prepreg sheet of the present embodiment can reduce the amount of solvent used as compared with the conventional method of diluting a thermosetting resin with a solvent, so that the viscosity of the resin composition 6 is relatively high. (For example, the viscosity at 23 ° C. is 2 to 20 Pa · s). For this reason, even when an inorganic filler having a large specific gravity is used, uniform dispersion can be promoted throughout the resin composition 6, so that there are few restrictions on the usable inorganic filler, and there is a demand for non-halogenation. It is possible to easily cope with problems such as maintaining moisture resistance.

  The release sheet 2 is made of a sheet made of paper or synthetic resin, and a release agent such as silicone is applied to the surface to which the resin composition 6 is applied. For the application of the resin composition 6 to the release sheet 2, various known coaters such as a blade coater, a roll coater, a bar coater, and an air knife coater can be used, but the resin composition is interposed between the release sheet 2 and the blade 4. The thing of the structure which passes 6 and makes the thickness of the resin composition 6 compulsorily constant can be used especially preferably.

  The resin composition 6 applied to the release sheet 2 is transported to the drying furnace 10 and heated. As the drying furnace 10, a known drying furnace such as a warm air drying furnace or a far-infrared drying furnace can be used, and in this embodiment, the release sheet 2 coated with the resin composition 6 passes at a constant speed. As is the case, the horizontally long type is used. The drying furnace 10 includes a middle greenhouse 12 and a high temperature chamber 14, and the introduced resin composition 6 is heated in the middle greenhouse 12 and then further heated in the high temperature chamber 14 higher than the middle greenhouse 12. .

  The heating temperature and heating time (passing time) in the middle greenhouse 12 and the high temperature chamber 14 are determined based on the boiling point of the solvent in the resin composition 6, and the middle greenhouse 12 is higher than room temperature (25 ° C.), The temperature and time are set lower than the boiling point of the solvent. Moreover, the high temperature chamber 14 is set to a temperature and time that are higher than the boiling point of the solvent and can maintain the thermosetting resin contained in the resin composition 6 in the B-stage state. As an example, when the solvent of the resin composition 6 is methyl ethyl ketone (boiling point: about 80 ° C.) and the thermosetting resin is an epoxy resin, the heating temperature and time of the middle greenhouse 12 are 50 to 70 ° C., 2 It is preferable to set the heating temperature and time of the high temperature chamber 14 to 90 to 120 ° C. and 2 to 10 minutes, respectively. Thus, the heating temperature of the resin composition 6 is first maintained in the middle greenhouse 12 at a temperature higher than normal temperature and lower than the boiling point of the solvent, and then increased in the high temperature chamber 14 to a temperature higher than the boiling point of the solvent. In addition to facilitating the evaporation of the solvent, it is possible to effectively prevent the formation of irregularities in the resin film due to the foaming phenomenon caused by the rapid heating of the solvent. As a result, a high-quality thermosetting resin film can be obtained in a short time. In the present embodiment, the heating process is performed by two-stage temperature changes of the middle greenhouse 12 and the high-temperature chamber 14, but the heating temperature can be increased by three or more stages. It is also possible to raise it continuously.

  By such a heating process, the thermosetting resin in the B stage state is reduced in thickness by evaporation of the solvent and remains on the release sheet 2. Since an inorganic filler is blended in the thermosetting resin, a sheet body having a relatively large film thickness of the thermosetting resin (for example, 50 to 200 μm) is discharged from the drying furnace 10. This film thickness can be set to a desired value by adjusting the thickness of the resin composition 6 using a coater in the coating process, or adjusting the specific gravity and blending ratio of the resin composition and the solvent.

  Thus, a sheet body 20 in which the B-stage thermosetting resin film 22 is formed on the release sheet 2 is obtained. The sheet body 20 is usually naturally cooled at room temperature and then wound on a roll and conveyed to perform a pressurizing process described later. However, the pressurizing process can be performed as it is without cooling. .

  As shown in FIG. 2, the pressurizing step pushes the surface of the sheet body 20 on which the thermosetting resin film 22 is formed against the upper and lower surfaces of the base material 30 fed out from a roll (not shown). The pair of sheet bodies 20 and 20 and the base material 30 which are carried out and applied are sandwiched between the pair of heat rolls 16 and 16 in a laminated state. The temperature of the heat rolls 16 and 16 is a temperature for maintaining the thermosetting resin film 22 in a prepreg state. For example, in the case of an epoxy resin, the temperature is 80 to 120 ° C.

  The base material 30 includes fiber base materials such as glass fiber, aramid fiber, carbon fiber, paper, etc. in addition to natural fibers such as pulp and cotton, and examples thereof include woven fabrics and non-woven fabrics. The base material 30 may be subjected to a surface treatment with a phenol resin, a silane coupling agent or the like in order to increase the bonding strength with the thermosetting resin film 22 such as an epoxy resin.

  The pressing force of the sheet bodies 20 and 20 to the base material 30 by the pair of heat rolls 16 and 16 is such that at least a part of the thermosetting resin film 22 is impregnated in the base material 30, so What is necessary is just to be the extent held. Thus, the prepreg sheet 40 having the thermosetting resin films 22 and 22 in the B stage state on both surfaces of the base material 30 is obtained.

  According to the method for producing a prepreg sheet of this embodiment, a resin composition containing a thermosetting resin dissolved in a solvent is not impregnated directly on a substrate, but is applied in advance to a release sheet with a predetermined thickness. Therefore, the thickness of the prepreg sheet can be adjusted regardless of the amount of the solvent. Therefore, the amount of the solvent can be reduced as much as possible to reduce the environmental load, and a high-quality prepreg sheet can be easily obtained.

  Further, in the heating step, the thermosetting resin can be made B-staged together with the evaporation of the solvent contained in the resin composition, so that temperature management is easy and a uniform B-stage state of the entire prepreg sheet is obtained. be able to.

  The prepreg sheet thus obtained is obtained by removing a release sheet, laminating a plurality of sheets, and superposing a metal foil such as a copper foil on both sides or one side as necessary, and then using a vacuum press molding machine or the like under vacuum. A high-quality laminate can be easily manufactured by hot-press molding. For example, when silica or alumina is blended as an inorganic filler, since the prepreg sheet has a sufficient thickness of thermosetting resin, it mainly suppresses the linear expansion coefficient in the thickness direction and improves the thermal conductivity. Can be achieved.

  Moreover, as shown in FIG. 3, by interposing FR-4 prepreg 44, which is a prepreg for a glass base epoxy resin substrate, between prepreg sheet 40 and copper foil 42, CEM-1 and CEM-3 It is also possible to create a laminated plate 50 equivalent to (ANSI grade).

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

  A resin composition having a blending ratio shown in Table 1 was applied on a release sheet using a coater, and passed through a drying furnace to evaporate the solvent, thereby creating a sheet body having an epoxy resin film in a B-stage state. . The thickness of the epoxy resin film after drying was 100 μm, and the blade gap of the coater was set to 110 μm so as to obtain such a film thickness. In the drying furnace, the heating temperature and time in the middle greenhouse were 60 ° C./5 minutes, and the heating temperature and time in the high temperature chamber were 100 ° C./10 minutes.

Next, a prepreg sheet in which the base material was impregnated with the resin was prepared by sandwiching the sheet body with a hot roll (temperature: about 80 ° C.) from above and below the base material (thickness: about 250 μm) made of linter paper. And 6 sheets of this prepreg sheet were piled up, copper foil was mounted up and down, and it heat-pressed with the vacuum press molding machine, and obtained the paper base material / epoxy resin laminated board with a thickness of 1.6 mm. This laminated board achieved a V-0 rating in flame retardant evaluation based on UL-94 without using environmentally hazardous substances such as halogenated flame retardants, phosphorus, phosphorus compounds, and antimony.

It is process drawing for demonstrating the application | coating process and heating process in the manufacturing method of the prepreg sheet which concerns on one Embodiment of this invention. It is process drawing for demonstrating the pressurization process in the manufacturing method of the prepreg sheet which concerns on one Embodiment of this invention. It is a schematic side view which shows an example of a laminated board.

Explanation of symbols

2 Release sheet 4 Blade 6 Resin composition 10 Drying furnace 12 Middle greenhouse 14 High greenhouse 16 Heat roll 20 Sheet body 22 Thermosetting resin film 30 Base material 40 Prepreg sheet 42 Copper foil 50 Laminate plate

Claims (4)

An application step of applying a resin composition containing a curing agent and an inorganic filler together with a thermosetting resin dissolved in a solvent to a release sheet;
A heating step of evaporating the solvent in the resin composition by heating the resin composition applied to the release sheet and bringing the thermosetting resin into a B-stage state;
A method for producing a prepreg sheet, comprising: a step of impregnating a base material with at least a part of the thermosetting resin by pressing a thermosetting resin in a B-stage state on both surfaces of the sheet-like base material. The prepreg sheet manufacturing method according to claim 1, wherein the coating step includes a step of making the thickness of the resin composition applied to the release sheet constant with a blade so that a desired resin thickness is obtained after the heating step. Method. The method for producing a prepreg sheet according to claim 1 or 2, wherein the heating step raises the heating temperature of the resin composition to a temperature higher than the normal temperature and lower than the boiling point of the solvent and then to a temperature higher than the boiling point of the solvent. . A laminate obtained by laminating a plurality of prepreg sheets obtained by the method for producing a prepreg sheet according to any one of claims 1 to 3, and subjecting the prepreg sheets to heat and pressure molding under vacuum.