JP2000273218A - Production of prepreg and laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a laminate having stable and excellent qualities without causing air pollution and with saving resource at a low cost. SOLUTION: A thermosetting resin and a powdery curing agent are used as essential components. A mixture of the components is provided with mechanical energy to cause a mechanochemical reaction. Then the resultant material is ground, dispersed and mixed by a medium stirring type mill to give a powdery resin composition, which is preferably uniformly mixed with a fine powder additive having 0.01-1 μm average particle diameter to give a powdery resin composition, which is made to exist at least on the surface of a sheetlike fiber base to give a prepreg. One prepreg or plural prepregs are laminated and heated under pressure to produce the laminate.

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, followed by pulverization by stirring with a medium, to provide uniform dispersion / mixing and impregnation into the base material is equivalent to that of a resin using a conventional solvent. Get
Further, based on this finding, the present inventors have made various studies and completed the present invention.

[0005]

SUMMARY OF THE INVENTION The present invention comprises a thermosetting resin and a curing agent as essential components, and imparts mechanical energy to a mixture of these components to cause a mechanochemical reaction. A method for producing a prepreg, characterized in that a powdery thermosetting resin composition obtained by pulverizing, dispersing, and mixing in at least the surface of a sheet-like fiber base material is used. And a curing agent is a powdery prepreg, and is a method for producing a prepreg in which an inorganic filler is blended before being pulverized, dispersed, and mixed by a medium stirring mill. 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 same is mixed with a sheet-like fiber base material (hereinafter, referred to as a sheet-like fiber substrate). A prepreg at least on the surface of a prepreg. Further, the present invention relates to a method for manufacturing a laminated board, comprising laminating one or more prepregs thus obtained, and applying heat and pressure.

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] Powder processing methods for applying mechanical energy for the mechanochemical reaction include Raikai machines, Henschel mixers, planetary mixers, ball mills,
There is mixing or kneading by a jet mill, an ong mill, a multi-stage mill-type kneading extruder or the like. Among these, Ongmill (Mechanofusion method manufactured by Hosokawa Micron Corporation),
Mixing or kneading with a multi-stage mill-type kneading extruder (manufactured by KCK Corporation: mechanochemical dispersion system, etc.) or a jet mill (manufactured by Nara Machinery Works, Ltd .: hybridizer system, etc.) is preferred. In order to perform it efficiently, a multi-stage mill-type kneading extruder (K
CK: Mechanochemical dispersion method).

[0010] In order to carry out the mechanochemical reaction, the softening point of the thermosetting resin is preferably 50 ° C or higher, more preferably 70 ° C or higher, and further preferably 80 ° C or higher. This is because heat of about 20 to 50 ° C. is generated due to friction, pulverization, and fusion between the powders or between the powder and the processing apparatus during the above-mentioned processing, so that this influence is 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 of the resin composition in a later step, so that the temperature is 150 ° C or less, particularly 130 ° C or less. Softening points are 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. .

After the mechanochemical reaction is caused to the thermosetting resin composition used in the present invention, an inorganic filler is preferably added, followed by pulverizing, dispersing and mixing to perform uniform dispersion. When inorganic filler is added, tracking resistance, heat resistance,
Properties such as a decrease in the 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 processing method for pulverizing, dispersing and mixing is carried out by using a medium stirring type mill. The basic structure of this apparatus is that various shapes (bar type, disk type, Pin type, paddle type,
Agitator having a screw type or the like and a medium having various diameters (for example, 20 mm or less, preferably 3 to 10 mm) and materials (for example, alumina, zirconia, silicon nitride, etc.). There are a tubular type and an annular type, and in the present invention, a flow type is suitable. For example, a horizontal continuous fine pulverizer having good productivity such as a dynamic mill and a dyno mill is preferable.

The particle size of the powder composition which is subjected to a mechanochemical reaction by applying mechanical energy and pulverized / dispersed / mixed by a medium stirring type mill is usually 1,000 μm or less, preferably 0.1 to 500 μm, More preferably, it is 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.

The addition of the fine powder additive can greatly improve the uniform dispersibility and flow characteristics of the powder composition. 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 whole powdery composition, any method can be used as long as it can uniformly disperse and mix the fine powder additive. For example, Henschel mixer,
Mixing using a raikai machine, a planetary mixer, a ball mill, or the like is included. 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.

[0018]

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 500 rpm for 5 minutes, and then a multi-stage mill-type kneading extruder ( KCK Corporation
Made mechanochemical dispersion system KCK
-80X2-V (6)) for 1 minute at a rotation speed of 200 rpm. To this powder, 100 parts by weight of aluminum hydroxide (CL-310, manufactured by Sumitomo Chemical Co., Ltd.) was added as an inorganic filler, and the mixture was stirred using a medium stirring mill (Mitsui Mining Co., Ltd. dry continuous fine grinding machine: dynamic mill). , Medium diameter 10m
m, a medium filling rate of 70%, and a rotation speed of 500 rpm to obtain a powder composition having an average particle size of 150 μm.

This powdery resin composition was coated on one side of a 100 g / m ² glass cloth 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 was obtained.
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 a rotation speed of 500 rpm for 5 minutes, and then a mechanofusion machine (AM manufactured by Hosokawa Micron) -15F) at 5 rpm and 5 rpm.
Minutes. To this powder, 50 parts by weight of aluminum hydroxide (CL-310, manufactured by Sumitomo Chemical Co., Ltd.) was added as an inorganic filler, and the mixture was stirred using a medium stirring mill (Mitsui Mining Co., Ltd. dry continuous fine grinding machine: dynamic mill). The medium was treated at a medium diameter of 8 mm, a medium filling rate of 70%, and a rotation speed of 500 rpm to obtain a powder composition having an average particle diameter 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 of 15 obtained in Example 3
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), 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 glass cloth with the resin was measured, and for the copper-clad laminate, the moldability, tensile strength, copper foil peeling strength, and solder heat resistance were measured. Properties and insulation resistance were measured. Table 1 shows the results.

[0028]

[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.

[0031]

According to the present invention, a mixture of a thermosetting resin and a curing agent is given mechanical energy to a mixture of essential components to cause a mechanochemical reaction.
Using a powdered thermosetting resin composition obtained by dispersion and mixing, preferably using a powdered resin composition further mixed with a fine powder additive having an average particle size of 0.01 to 1 μm, prepreg and Since laminates are manufactured, uniform mixing of each component and excellent impregnation into the base material are excellent, and even though no organic solvent is used, a stable laminate having good quality such as electric properties and heat resistance can be obtained. be able to. Since no organic solvent is used, resource saving, energy saving, and reduction of air pollution are achieved, and resource saving and energy saving are also excellent in terms of cost reduction. Thus, the present invention is suitable as an industrial method for producing a prepreg and a laminate.

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Claims (7)

[Claims] 1. A thermosetting resin and a curing agent are essential components, and a mechanical energy is applied to a mixture of these components to cause a mechanochemical reaction. Then, the mixture is pulverized, dispersed and mixed by a medium stirring mill. A method for producing a prepreg, characterized in that the obtained powdery thermosetting resin composition is present at least on the surface of a sheet-like fiber substrate. 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 before being pulverized, dispersed and mixed by a medium stirring mill. 4. A powdery resin composition obtained by adding a fine powder additive having an average particle diameter of 0.01 to 1 μm to a powdery thermosetting resin composition and uniformly mixing the same with at least a sheet-like fiber base material. 4. The method for producing a prepreg according to claim 1, wherein the prepreg is present on a surface. 5. The method for producing a prepreg according to claim 1, wherein the apparatus for causing the mechanochemical reaction is a jet mill, an ong mill, or a multi-stage mill-type kneading extruder. 6. The method for producing a prepreg according to claim 1, wherein the medium stirring type mill is a dry continuous type medium stirring type fine pulverizer. 7. A method for manufacturing a laminate, comprising laminating one or more prepregs according to claim 1, 2, 3, 4, 5, or 6, and applying heat and pressure.