JP2000271930A - Manufacture of prepreg and laminated sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a laminated sheet, which does not pollute air and can save resources and is stable and favorable in quality, at low cost. SOLUTION: A mechanochemical reaction is taken place in a mixture of the essential components of a thermosetting resin and a hardener with a medium agitating mill so as to obtain a powdery thermosetting resin composition through grinding, dispersion and mixing or preferably, through the addition of fine powdered additive having the average particle diameter of 0.01-1 ηm, a powdery resin composition. By existing the composition at least on the surface of a sheet-like fibrous base material, a prepreg is manufactured. By applying heat and pressure on one sheet or a plurality of piled up sheets of the prepreg, a laminated sheet is manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prepreg and a laminated board suitable for a printed circuit board particularly used for electric equipment, electronic equipment, communication equipment and the like.

[0002]

2. Description of the Related Art As for printed circuit boards, demands for downsizing and high functionality are becoming stronger, but price competition is fierce. In particular, multilayer laminated boards, glass cloth base epoxy resin laminated boards, and glass nonwoven fabrics used for printed circuit boards are particularly important. Is a middle layer base material and a glass woven fabric is used as a surface layer base material, and a laminated board formed by impregnating with epoxy resin and heating and pressing (hereinafter referred to as a composite laminated board) is a major issue in terms of cost reduction. ing. In recent years, measures against global warming and reduction of environmental pollution have been required. Conventionally, a large amount of solvent has been used in a process of manufacturing a prepreg or a laminated board used for these in view of resin impregnation of the base material and uniformity of the resin. On the other hand, this large amount of solvent evaporates in the coating and drying step and is released to the atmosphere as it is without being present in the product, or it is treated by a combustion treatment device and released to the atmosphere as carbon dioxide gas or the like. Therefore, there is a problem that causes air pollution and global warming. On the other hand, it has been difficult to reduce the amount of solvent and thereby reduce the cost due to manufacturing problems such as resin impregnation of the base material.

As a technique for eliminating the solvent, studies have been made to heat and mix a resin having a low melting point or a liquid resin to uniformly mix and apply the solution. However, the heating temperature during continuous production cannot be sufficiently uniform. In addition, there is a problem that solidification of the thermosetting resin during heating and gelation of the thermosetting resin due to a decrease in the temperature, and difficulty in cleaning the facility due to the consolidation, make continuous production difficult. On the other hand, when the powdery resin is applied as it is, there is a problem that uniform mixing and application cannot be performed, and partial curing occurs and impregnation of the substrate cannot be performed.

[0004]

DISCLOSURE OF THE INVENTION The present invention has been studied to obtain a prepreg using a solvent-free resin and a laminate using the prepreg, which have been conventionally difficult to produce. The fact that the powder is subjected to a mechanochemical reaction and that the powder is subjected to a mechanochemical reaction and is uniformly mixed and impregnated into the substrate by pulverization, dispersion, and mixing becomes equivalent to a resin using a conventional solvent. Based on this finding, various studies have been made to complete the present invention.

[0005]

According to the present invention, a thermosetting resin and a curing agent are essential components, and a mixture of these components is caused to undergo a mechanochemical reaction in a medium stirring mill, and is crushed, dispersed and mixed. A method for producing a prepreg, characterized in that the powdery thermosetting resin composition obtained as described above is present on at least the surface of a sheet-like fiber base material, wherein the thermosetting resin and the curing agent are preferably in powder form. This is a method for producing a prepreg in which an inorganic filler is blended together with a thermosetting resin and a curing agent. Further, a powdery resin composition obtained by adding a fine powder additive having an average particle size of 0.01 to 1 μm to the above powdery thermosetting resin composition and uniformly mixing the resulting mixture with at least the surface of a sheet-like fiber substrate. A method for producing a prepreg, characterized in that the method further comprises the step of laminating one or more prepregs obtained in this manner, and heating and pressurizing the laminate. .

The thermosetting resin used in the present invention is usually in the form of a powder, and is preferably an epoxy resin. In addition, a polyimide resin, a polyester resin, a phenol resin and the like can be used. When the thermosetting resin is an epoxy resin, as a curing agent, from the viewpoint of heat resistance and electrical properties, amine-based, especially dicyandiamide and aromatic amine,
And novolak resins, but acid anhydrides, imidazole compounds and the like can also be used. The curing agent is preferably in the form of a powder, but when the amount is small (for example, 20% by weight or less with respect to the resin), the curing agent may be in a liquid state. It is possible. Preferably, a curing accelerator is used. The curing accelerator is also preferably in the form of powder,
Liquid substances can be used as described above. As such a curing accelerator, an imidazole compound, a tertiary amine, or the like can be used. These components are not limited to those described above.

The particle size of these powders is usually 100
0 μm or less, preferably 0.1 to 500 μm, more preferably 0.1 to 200 μm. This is because if the particle size exceeds 1000 μm, the surface area with respect to the particle weight becomes small, the number of contact points of each component such as a thermosetting resin, a curing agent and a curing accelerator decreases, and uniform dispersion becomes difficult. It may react at a different ratio than the target ratio,
There is a possibility that a uniform reaction is not performed. In the case of the mechanochemical reaction, the particle size of the thermosetting resin is preferably 5 to 15 times the particle size of the curing agent (and the curing accelerator). This is because the curing agent (and the curing accelerator) is easily fused to the thermosetting resin in this range.

[0008] The modification by mechanochemical reaction is "a modification of a solid by a solid, which utilizes the surface activity of particles by grinding, grinding, friction, and contact, and surface appliances. The activity itself is a crystalline form. In some cases, the dissolution or thermal decomposition rate is modified by increasing the transition energy or strain energy, or mechanical strength or magnetic properties are obtained. In other cases, surface activity is used for reaction or adhesion with other substances. Uses mechanical impact energy to perform not only physical modification but also chemical modification such as adhesion by electric charge or magnetism by friction, contact, embedding of modifier in nuclear material, formation of film by melting, etc. ("Overview of Practical Surface Modification Technologies" edited by the Material Technology Research Association, Industrial Technology Service Center, published March 25, 1993, p786)
Things. The present invention utilizes chemical modification by a mechanochemical reaction, but also includes a case where a solid and a liquid are chemically modified by mechanical energy.

[0009] A treatment method for applying mechanical energy for the mechanochemical reaction and for pulverizing, dispersing, and mixing by stirring is performed using a medium stirring type mill. The basic structure of this device is agitator having various shapes (bar type, disk type, pin type, paddle type, screw type, etc.) and various diameters (for example, 20 mm or less, preferably 3 to 10 mm), which are agitating means. (E.g., alumina, zirconia, silicon nitride, etc.), and includes a tower type, a tank type, a flow tube type, and an annular type. In the present invention, the flow tube type is appropriate.
For example, a horizontal continuous fine pulverizer with good productivity such as a dynamic mill and a dyno mill is preferable.

In order to carry out the mechanochemical reaction and the stirring and grinding of the medium, the softening point of the thermosetting resin is preferably 50
° C or higher, more preferably 70 ° C or higher, still more preferably 80 ° C or higher. This is due to friction, pulverization and fusion between the powders or between the powder and the processing equipment during the above processing.
Since heat of about 50 ° C. is generated, this effect is to be minimized. On the other hand, even if the softening point is too high, an effective mechanochemical reaction is difficult to be performed, and it is difficult to impregnate the base material with the resin composition in a later step.
A softening point of 0 ° C., especially 130 ° C. or less is preferred. Each component such as a powdery thermosetting resin and a curing agent is preferably mixed as uniformly as possible with a Henschel mixer or the like after pulverizing to the above particle size in advance before powder treatment for mechanochemical reaction. .

It is preferable to add an inorganic filler to the thermosetting resin composition used in the present invention in advance of causing a mechanochemical reaction and stirring, pulverizing, mixing and uniformly dispersing the thermosetting resin composition. When an inorganic filler is added, characteristics such as tracking resistance, heat resistance, and a decrease in coefficient of thermal expansion can be imparted. Such inorganic fillers include aluminum hydroxide, magnesium hydroxide, calcium carbonate, talc, wollastonite, alumina, silica, unfired clay, fired clay, barium sulfate and the like. These particle sizes are the same as above. In addition, additives such as a coupling agent may be blended.

The particle size of the uniformly dispersed and mixed powdery resin composition which has been subjected to the mechanochemical reaction and pulverized by stirring the medium as described above is usually 1000 μm or less, preferably 0.1 to 500 μm. , More preferably 0.1 to 100 μm. Such a particle size can be used to improve the flowability of powder during spraying or application, the flowability during heating and melting, the smoothness of the surface, the improvement of impregnation of resin into the sheet-like fiber base material, and the stabilization of weight distribution and the like. Suitable for The powdery resin composition is then used as is or with an average particle size of 0.0
A prepreg is obtained by blending and uniformly mixing a fine powder additive of 1 to 1 μm and allowing it to exist on at least the surface of the sheet-like fiber base material.

By blending the fine powder additive, the uniform dispersibility and flow characteristics of the powdery composition can be greatly improved. By such a technique, uniform distribution can be achieved when the powdery composition is applied to and impregnated on the sheet-like substrate, and uniform impregnation can be achieved by obtaining smoothness of the powder application surface. As the fine powder additive, an inorganic fine powder is desirable, but an organic fine powder can also be used. The average particle size is 0.01 to 1 μm, preferably 0.01 to 0.1 μm (specific surface area: 50 to 500 m ² /
g). Such fine powder additives include silica fine powder and titanium oxide fine powder. When the average particle size exceeds 1 μm, the specific surface area decreases, the number of particles per unit weight decreases, and the difference in particle size between the powdered resin and the powdered curing agent, which are the main components, decreases, resulting in fluidization. There is a possibility that the bearing effect for improving the performance cannot be sufficiently obtained. The bearing effect in powder means that fine particles are present at the contact points between particles having relatively large particle diameters, so that the movement of particles having large particle diameters becomes more free and the fluidity of the powdery composition as a whole is improved. It is to improve. In the case of a fine powder additive, the particle diameter may be 2 to 10 μm due to secondary aggregation, but if such an additive has an average primary particle diameter of 0.01 to 1 μm, it is sufficient. effective. As a treatment method for improving the fluidity of the entire powdery composition, any method may be used as long as it can uniformly disperse and mix the fine powder additive,
Examples of such a treatment method include mixing using a Henschel mixer, a Raikai machine, a planetary mixer, a ball mill, or the like. In particular, a ball mill or a Henschel mixer having a shearing force is preferably used for the secondary aggregated fine powder.

The mixed powdery composition is uniformly dispersed on the sheet-like fiber substrate by spraying or coating. The amount of the powdery composition varies depending on the fiber material, properties and weight (per unit area) of the sheet-like fiber base material, but is usually about 40 to 60% of the weight of the sheet-like fiber base material. The method of causing the powdery composition to be present on the sheet-like fiber substrate includes a method of sprinkling from the upper surface of the sheet-like fiber substrate, an electrostatic coating method, a fluid immersion method, a spraying method by spraying, a knife coater, a comma knife coater, a die coater, and the like. There is no particular limitation on the coating method using various coaters. In addition, if the sheet-like fiber base material is previously heated to about 60 to 100 ° C., it adheres well to the fibers when the powdery composition is sprayed, and penetrates well into the base material by subsequent heating. , A good prepreg is obtained. As a sheet-like fiber substrate,
In addition to glass fiber base materials such as glass cloth and glass non-woven cloth,
Paper, woven or non-woven fabrics made of synthetic fibers, etc., woven fabrics, non-woven fabrics, mats, etc. made of metal fibers, carbon fibers, mineral fibers, etc., and these base materials can be used alone or in combination. Is also good.

The prepreg obtained as described above is
One or more of the sheets are laminated with a metal foil such as a copper foil as necessary, and heated and pressed by a usual method to form a laminate. The method for producing a prepreg and a laminate according to the present invention can be easily produced by using a powdery resin composition without substantially changing the performance of the obtained prepreg or laminate, and can save resources and eliminate air by using no solvent. Pollution can be reduced, energy can be saved, and cost can be reduced. The present invention relates to a powdery material (resin,
And a mechanochemical reaction. The powdery materials are uniformly dispersed and bonded by such a technique, and the resulting powdery resin composition is formed into a sheet. When coating and impregnating on a fiber base material, uniform impregnation is made possible by obtaining uniform distribution and smoothness of the powder coated surface.

[0016]

Next, examples of the present invention will be specifically described together with comparative examples.

Example 1 A powdery epoxy resin having an average particle size of 150 μm (brominated epoxy resin Ep manufactured by Yuka Shell Co., Ltd.)
5048, epoxy equivalent 675) 100 parts by weight, powdery curing agent (dicyandiamide) 5 having an average particle size of 15 μm 5
Parts by weight and 1 part by weight of a powdery curing accelerator (2-ethyl-4-methylimidazole) having an average particle size of 15 μm are mixed with a Henschel mixer at a rotation speed of 500 rpm for 5 minutes, and then the powder is inorganic-filled. As a material, 50 parts by weight of aluminum hydroxide (CL-310 manufactured by Sumitomo Chemical Co., Ltd.) was added, and a medium agitating mill (Mitsui Mining Co., Ltd. dry continuous pulverizer: dynamic mill) was used. A powder composition having a filling rate of 70%, a rotation speed of 500 rpm and an average particle size of 150 μm was obtained.

This powdery resin composition was coated on one side of a glass cloth of 100 g / m ² with a knife coater at a gap of 0.2 m.
m and the resin weight was 50 g / m ² . Then, after heating with a dryer at 170 ° C. for 30 seconds, the glass cloth was turned upside down and the other surface was adjusted to a gap of 0.2 mm with a knife coater so that the resin weight was 50 g / g.
m ^2, and dried by a dryer at 170 ° C. for 3 minutes to obtain a prepreg. This prepreg is 2
A copper foil having a thickness of 18 μm is laminated on the upper and lower sides, and the temperature is 165 ° C. and the pressure is 60 kg / cm ² .
It was heated and pressed for 0 minutes to produce a copper-clad laminate having a thickness of 0.22 mm.

Example 2 The average particle size of 15 obtained in Example 1
To 100 parts by weight of a 0-μm powdery resin composition, 1 part by weight of fine powdered silica (Aerosil # 200 manufactured by Nippon Aerosil Co., Ltd.) having an average particle diameter of 0.05 μm was added, and mixed at 500 rpm for 5 minutes using a Henschel mixer. did. A prepreg was obtained from this powdery composition in the same manner as in Example 1, and a copper-clad laminate having a thickness of 0.22 mm was produced using the prepreg.

Example 3 100 parts by weight of a powdery epoxy resin (Ep5048) having an average particle size of 150 μm and a powdery curing agent (dicyandiamide) 5 having an average particle size of 15 μm
Parts by weight and 1 part by weight of a powdery curing accelerator (2-ethyl-4-methylimidazole) having an average particle size of 15 μm were mixed with a Henschel mixer at 500 rpm for 5 minutes, and then mixed with a medium stirring mill (Mitsui Mining ( Medium diameter 10m using a dry continuous type fine grinding machine dynamic mill)
m, a medium filling rate of 65%, a rotation speed of 500 rpm, and a processed powder composition having an average particle size of 150 μm. Thereafter, a prepreg was obtained in the same manner as in Example 1, and then a copper-clad laminate having a thickness of 0.22 mm was produced using the prepreg.

Example 4 The average particle size obtained in Example 3 was 20.
To 100 parts by weight of a 0-μm powdery resin composition, 1 part by weight of fine powdered silica (Carplex # 67 manufactured by Shionogi & Co., Ltd.) having an average particle diameter of 0.1 μm was added, and the rotation speed was 500 rpm for 5 minutes using a Henschel mixer. It was mixed. A prepreg was obtained from this powdery composition in the same manner as in Example 1, and a copper-clad laminate having a thickness of 0.22 mm was produced using the prepreg.

Comparative Example 1 100 parts by weight of a powdery epoxy resin (brominated epoxy resin Ep5048, oil equivalent shell, epoxy equivalent: 675), 5 parts by weight of a powdery curing agent (dicyandiamide), and a powdery curing accelerator (2-ethyl-
4-methylimidazole) mixed at a ratio of 1 part by weight, using two rolls having a diameter of 12 inches, and rotating at a high speed side of 20 rpm
m, high-speed roll temperature 100 ° C, low-speed roll temperature 90
At 30 ° C. and a rotation ratio of 1.5: 1, taken out in the form of a sheet, cooled with cold air, and then crushed with a fine pulverizer at an average particle size of 200 μm.
m. A prepreg was obtained from this powdery composition in the same manner as in Example 1, and a copper-clad laminate having a thickness of 0.22 mm was produced using the prepreg.

Comparative Example 2 100 parts by weight of a powdery epoxy resin (brominated epoxy Ep5048 manufactured by Yuka Shell)
5 parts by weight of powdery curing agent (dicyandiamide), powdery curing accelerator (2-ethyl-4-methylimidazole)
After mixing at a ratio of 1 part by weight, was melted by warming at this powder 100 ° C., impregnated with a glass cloth of 100 g / m ² so as to 100 g / m ² of resin solids The prepreg was dried by drying at 170 ° C. for 2 minutes.
Two prepregs were superimposed, and a copper foil having a thickness of 18 μm was superimposed on and under the prepreg.
Heat-press molding at 0 kg / cm ² for 90 minutes to give a thickness of 0.
A 22 mm copper-clad laminate was produced.

Comparative Example 3 100 parts by weight of an epoxy resin (brominated epoxy Ep5048 manufactured by Yuka Shell), 5 parts by weight of a curing agent (dicyandiamide), and 1 part by weight of a curing accelerator (2-ethyl-4-methylimidazole) The mixture in the ratio was dissolved in 100 parts by weight of methylcellosolve. The varnish was adjusted to a resin solid content of 100 g / m ² by 1 g.
After soaking and impregnating 00 g / m ² glass cloth,
The prepreg was dried by drying at 70 ° C. for 3 minutes to obtain a prepreg. Two prepregs were laminated, and a copper foil having a thickness of 18 μm was laminated on top and bottom of the prepreg.
Heat / press molding at 90 kg / cm ² for 90 minutes
A 2 mm copper-clad laminate was produced.

In the above Examples and Comparative Examples, for the prepreg, the impregnating property of the resin into the glass cloth was measured, and for the copper-clad laminate, the moldability, tensile strength, copper foil peeling strength, and solder heat resistance were measured. The properties were measured. Table 1 shows the results.

[0026]

[Table 1]

(Measurement method) Impregnating property: The presence or absence of voids between glass fibers was confirmed with a prepreg under a stereoscopic microscope. 2. Formability: The copper foil of the copper-clad laminate is etched, and the presence or absence of precipitation of a curing agent or the like is visually observed to evaluate the dispersibility. 3. Tensile strength: Etching copper foil of copper clad laminate,
After cutting to 10 × 100 mm, the tensile strength was measured with Tensilon. 4. 4. Copper foil peel strength: according to JIS C6481 Solder heat resistance: A laminate of 50 × 50 mm is subjected to 260 ° C.
Was floated in a solder bath for 3 minutes, and the presence or absence of blisters was measured. 6. Insulation resistance: According to JIS C6481

As for the manufacturing cost, the method of the embodiment does not use a solvent, so that the laminated board obtained in the embodiment is reduced in cost by about 30 to 40% as compared with that obtained in the comparative example 3. Was completed. Moreover, about the comparative example 2,
In the step of melting the resin at 100 ° C., the change over time in the curing characteristics of the resin was remarkable, and the resin adhered to the equipment hardened, making cleaning difficult.

[0029]

According to the present invention, a mixture containing a thermosetting resin and a curing agent as essential components is given mechanical energy by a medium stirring mill to cause a mechanochemical reaction, and is also obtained by pulverizing, dispersing and mixing. Using a powdered thermosetting resin composition, preferably further having an average particle size of 0.01 to 1 μm
Since prepregs and laminates are manufactured using a powdery resin composition blended with a fine powder additive, uniform mixing of each component and excellent impregnation into a substrate are achieved, and even though an organic solvent is not used. In addition, a laminate having good quality such as electric characteristics and heat resistance can be stably obtained. Since no organic solvent is used, there is no air pollution and resources can be saved. It is possible to obtain a good and stable laminate in terms of quality.
It is excellent in terms of cost reduction, and is suitable as an industrial method for manufacturing a laminate.

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Claims (6)

[Claims] A thermosetting resin and a curing agent are essential components, and a mixture of these components is caused to undergo a mechanochemical reaction by a medium stirring mill, and is also powdered thermosetting obtained by pulverization, dispersion and mixing. A method for producing a prepreg, wherein the conductive resin composition is present on at least the surface of a sheet-like fiber base material. 2. The method for producing a prepreg according to claim 1, wherein the thermosetting resin and the curing agent are in a powder form. 3. The method for producing a prepreg according to claim 1, wherein an inorganic filler is blended together with the thermosetting resin and the curing agent. 4. A powdery resin composition obtained by adding and uniformly mixing a fine powder additive having an average particle size of 0.01 to 1 μm to a powdery thermosetting resin composition, The method for producing a prepreg according to claim 1, wherein the prepreg is present at least on a surface. 5. The method for producing a prepreg according to claim 1, wherein the medium stirring mill is a dry continuous stirring mill. 6. A method for manufacturing a laminate, comprising laminating one or more prepregs according to claim 1, 2, 3, 4 or 5, and applying heat and pressure.