JP2005307371A - Wet process nonwoven fabric and prepreg, composite material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wet process nonwoven fabric having good permeability of a resin component, to provide a composite material having good surface smoothness by using this, and to provide a prepreg used therefor.
A wet process nonwoven fabric comprising a binder component that binds inorganic fibers and fibers, wherein the ratio of the number of adjacent fibers to the total number of fibers in the cross section of the nonwoven fabric is 5% or more and 95% or less. Wet method nonwoven fabric. It is preferable that the ratio (Z / X) of the adjacent fiber number Z in the thickness direction and the adjacent fiber number X in the plane direction in the nonwoven fabric cross section is 0.8 or less, and the average fiber diameter of the inorganic fibers is 4 μm to 20 μm. And the average fiber length is preferably 1 mm to 25 mm. A composite material can be produced by press-molding at least one prepreg having a resin component adhered to the wet method nonwoven fabric.
[Selection figure] None

Description

  The present invention relates to a wet process nonwoven fabric using inorganic fibers, a prepreg using the same, and a composite material. More specifically, the present invention relates to a wet method nonwoven fabric, a prepreg, and a composite material suitable for producing a composite material in which the resin component used in the prepreg has good permeability and excellent surface smoothness.

  FRP (Fiber Reinforced Plastics) improves the strength of the resin itself by including fibers in a resin (plastic) serving as a matrix, as called fiber reinforced plastics. One type of FRP is a printed wiring board used for an electric circuit board or a decorative board used for a building material among plate-like composite materials obtained by press molding using a wet process inorganic fiber nonwoven fabric as a fiber. In order to reduce the water absorption rate or to obtain nonflammability, a large amount of pigment is blended in the matrix resin.

In order to obtain a nonwoven fabric having a good texture, conventional wet method nonwoven fabrics are made by dispersing fibers one by one in order to maintain the dispersion state. For example, a non-woven fabric with improved texture is proposed by dispersing glass fibers using a bendine-type surfactant and using anionic polyacrylamide as an adhesive to improve fiber dispersibility and stability. (See Patent Document 1).
Further, a composite material has been proposed which is made by press-molding a plurality of prepregs obtained by impregnating and drying a glass fiber nonwoven fabric with a component comprising a phenol resin and an inorganic filler (see Patent Documents 2 and 3). Since these non-woven fabrics have discrete fibers, the non-woven fabric has almost no adjacent fibers in the non-woven cross section except near the fiber intersection. When a resin component containing an inorganic filler is attached to such a conventional wet method nonwoven fabric of inorganic fibers, the opening of the nonwoven fabric is small, and the permeability of the inorganic filler and resin component to the nonwoven fabric is poor, resulting in a composite The surface smoothness of the material tended to deteriorate.

In addition, for the purpose of improving the impact resistance of FRP, a method has already been proposed in which 20% by mass or more of fibers obtained by bundling 100 or more fibers are contained in a wet process nonwoven fabric composed of a binder component that binds to inorganic fibers. (See Patent Document 4). However, a nonwoven fabric containing 20% by mass or more of 100 or more concentrated inorganic fibers has a problem of poor texture when the nonwoven fabric is thin.
JP-A-4-298208 JP-A-8-207201 JP-A-11-277705 JP-A-10-292254

  An object of the present invention is to provide a wet process nonwoven fabric having good permeability of a resin component, to provide a composite material having good surface smoothness by using this, and to provide a prepreg used therefor.

In order to solve the above problems, the present invention employs the following configurations (1) to (11).
(1) A wet method nonwoven fabric comprising a binder component that binds inorganic fibers and fibers, wherein the ratio of the number of adjacent fibers to the total number of fibers in the cross section of the nonwoven fabric is 5% to 95%. Method nonwoven fabric.
(2) The ratio (Z / X) of the number of adjacent fibers in the thickness direction Z and the number of adjacent fibers in the plane direction X (Z / X) of the adjacent fibers in the nonwoven fabric cross section is 0.8 or less. Wet method nonwoven fabric.
(3) The wet method nonwoven fabric according to (1) or (2) above, wherein the inorganic fiber has an average fiber diameter of 4 μm to 20 μm and an average fiber length of 1 mm to 25 mm.
(4) The wet method nonwoven fabric according to any one of the above (1) to (3), wherein the inorganic fiber is a glass fiber.
(5) Density of the wet method ^{nonwoven, 0.10g / cm 3 ~0.25g / cm} 3 in the above, characterized in that (1) to (4) a wet method nonwoven fabric according to any one of.
(6) The wet process nonwoven fabric according to any one of (1) to (5) above, wherein the binder amount is 3% by mass to 25% by mass.
(7) A prepreg in which a resin component is adhered to the wet method nonwoven fabric according to any one of (1) to (6).
(8) The ratio of the number of adjacent fibers in which the ratio (Z / X) of the number of adjacent fibers Z in the thickness direction and the number X of adjacent fibers in the planar direction in the cross section of the prepreg is 0.8 or less is 5% or more and 95% or less. The prepreg as described in (7) above, wherein
(9) A composite material obtained by press molding using at least one prepreg according to claim 8.
(10) The ratio of the number of adjacent fibers in which the ratio (Z / X) of the number of adjacent fibers Z in the thickness direction to the number X of adjacent fibers in the planar direction in the cross section of the composite material is 0.8 or less is 5% or more and 95% or less. The composite material as described in (9) above, comprising a layer that is
(11) The composite material according to (10), wherein the composite material is a printed wiring board or a decorative board.

  INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an inorganic fiber nonwoven fabric having good resin component permeability, a prepreg using the same, and a composite material, which are extremely useful industrially.

This was achieved by allowing the bundled fibers to be present in a part of the individual fibers that are present in the conventional wet method nonwoven fabric. The reason why the permeability of the resin component is improved is not clear, but perhaps the inclusion of bundling fibers increases the opening of the nonwoven fabric, making it easier for the viscous resin component to penetrate into the nonwoven fabric and penetrates into the nonwoven fabric well. .
However, as in Patent Document 4 in the prior art, generally, a nonwoven fabric in which concentrated fibers are present has a poor texture. For example, if the penetration of the resin component is improved by increasing the opening, the texture of the nonwoven fabric is not improved. Due to the deterioration, the surface smoothness of the composite material is not improved. As a result of extensive studies, the present invention has succeeded in producing a wet-type nonwoven fabric having a good texture despite the presence of concentrated fibers.
As a factor that determines the texture, we have found that the proportion of bundled fibers present in the nonwoven fabric is important. (Note that the term “bundling” refers to a state in which a plurality of fibers (two or more) are gathered in the fiber longitudinal direction.)

In practice, it is very difficult to accurately determine the ratio of the bundled fibers in the nonwoven fabric. As a result of extensive studies, it was found that there is a relationship between the ratio of the number of adjacent fibers that can be easily obtained by observing the cross section of the nonwoven fabric and the texture.
That is, in the present invention, the ratio of the number of adjacent fibers to the total number of fibers in the cross section of the nonwoven fabric needs to be 5% or more and 95% or less. If it is less than 5%, the effect on the opening of the nonwoven fabric is small, and if it is more than 95%, the texture of the nonwoven fabric tends to be poor. More preferably, the ratio of the number of adjacent fibers is 10% or less and 75%, and 15% or less and 50% or more is very preferable.

The term “adjacent” in the present invention refers to the distance between line segments connecting the centers of any two fibers when observing a cross section of one nonwoven fabric, and the distance between the intersections of the two intersections where the line segments intersect with the fibers. When L2 satisfies (L1) ≧ (3 × L2), the two fibers are considered to be adjacent to each other. However, while being regarded as adjacent fibers in this definition, they are not necessarily bundled fibers. For example, even if the fibers are dispersed one by one, if the fibers have intersections, they are regarded as adjacent in this definition. However, since the frequency of intersections between fibers in one cross section is low and the effect is small, it is sufficient to use the numerical value of the ratio of the number of adjacent fibers in the total number of fibers in the cross section of the nonwoven fabric. The state can be grasped.
Among the adjacent fiber bundles that are aggregates of adjacent fibers satisfying (L1) ≧ (3 × L2), the number of adjacent fibers Z in the thickness direction in the nonwoven fabric cross section and the plane direction perpendicular to the thickness direction It is preferable to use adjacent fibers having a ratio (Z / X) of the number X of adjacent fibers of 0.8 or less. When the number of adjacent fibers is counted as an adjacent fiber having a ratio (Z / X) value greater than 0.8, the permeability of the resin component may deteriorate, although the reason is not clear. The ratio (Z / X) value is more preferably 0.7 or less, and even more preferably 0.6 or less. The observation cross-sectional area for determining the number of fibers is at least 0.2 mm ² or more, preferably 0.4 mm ² or more. When the observation area is smaller than 0.2 mm ² , the characteristics of the manufactured nonwoven fabric may not be sufficiently grasped. In the present invention, the number of inorganic fibers alone is counted.

The ratio (Z / X) value can be obtained, for example, in the case of a cross section of a nonwoven fabric as shown in FIG. 1 by using adjacent fiber bundles in which (1), (2), and (3) satisfy (L1) ≧ (3 × L2), respectively. is there. (1) (2) (3) (Z / X) value in each adjacent fiber bundle is the number of adjacent fibers Z = 1 in the thickness direction and the number of adjacent fibers X = 6 in the plane direction in the case of (1) Therefore, (Z / X) = 1/6 = 0.167.
In the case of (2), the number of adjacent fibers in the thickness direction Z = 2, the number of adjacent fibers in the plane direction X = 7, so Z / X value = 2/7 = 0.286, in the case of (3) The number of adjacent fibers Z in the vertical direction Z = 2.5, the number of adjacent fibers X in the plane direction X = 6.5, and therefore Z / X value = 2.5 / 6.5 = 0.385. Thus, Z and X are the maximum value in the Z (thickness) direction and the maximum value in the X (plane) direction in each adjacent fiber bundle.

The nonwoven fabric of the present invention is a wet method nonwoven fabric produced by a wet method. A known papermaking technique can be used as the wet method. For example, a well-known paper machine such as a long net, a round net, an inclined wire, and a twin wire, and a hand-making machine used by a person skilled in the art for examination at a laboratory level can be used.
The process of forming the shape of the nonwoven fabric in which the ratio (Z / X) of the number of adjacent fibers Z in the thickness direction and the number X of adjacent fibers in the planar direction in the nonwoven fabric cross section satisfies 0.8 or less is mainly in the wire part. It is formed in a process in which a fiber dispersion containing bundles is made by a wire (a process in which water is removed from the wire). In the present invention, press rolls and felt can be pressed on the wire part and / or the dryer part to further enhance the effect.

  The inorganic fiber of the present invention preferably has an average fiber diameter (the average fiber diameter is an average fiber diameter when converted into a perfect circle) of 4 μm to 20 μm and an average fiber length of 1 mm to 25 mm. More preferably, the average fiber diameter is 4 μm to 15 μm, and the average fiber length is 2 mm to 15 mm. When the average fiber diameter is less than 4 μm and / or the average fiber length is less than 1 mm, it is not preferable because it may be harmful to health as with asbestos. When the average fiber diameter is greater than 20 μm and / or the average fiber length is 25 mm. If it is larger, there is a problem that the nonwoven fabric tends to be poorly formed.

Examples of the inorganic fiber of the present invention include ceramic fiber, glass fiber, and carbon fiber. Among these, glass fiber is more preferable from the viewpoint of price. Examples of the glass fiber include E glass fiber, D glass fiber, S glass fiber, NE glass fiber, C glass fiber, quartz glass fiber, and high silicate glass fiber.
The inorganic fiber of the present invention preferably has a circular cross section from the viewpoint of cost. However, the object of the present invention is not limited to any cross section (for example, oval, eyebrows, flat, star shape, etc.). Can be achieved.

Nonwoven Density of the present invention is preferably ^{0.10g / cm 3 ~0.25g / cm 3} . If it is less than 0.10 g / cm ³ , surface smoothness may not be improved when molding up to a composite material. On the other hand, if it is larger than 0.25 g / cm ³ , the porosity of the non-woven fabric becomes small, so that the amount of the resin component attached to the composite material may be insufficient. Nonwoven density is more preferably if ^{0.13g / cm 3 ~0.21g / cm 3} , further preferably if ^{0.16g / cm 3 ~0.19g / cm 3} . The nonwoven fabric density is preferably measured at 50 KPa based on JIS P-8118.
The basis weight of the nonwoven fabric is preferably from ^{5g / m 2 ~300g / m 2} , more preferably ^{10g / m 2 ~200g / m 2} , more Konomashiki is ^{15 g / m 2 ~150 g /} m 2 .

  The nonwoven fabric of the present invention preferably has a binder amount of 3% by mass to 25% by mass. When the amount is less than 3% by mass, the strength of the nonwoven fabric is weak and easily torn, and when it is more than 25% by mass, the resin component used when making the prepreg may be difficult to adhere. The amount of the binder is more preferably 4% by mass to 20% by mass, and further preferably 6% by mass to 15% by mass.

  When the binder component used in the present invention uses a binder fiber or powder binder, it is preferably included in advance in a fiber dispersion containing a bundle of bundled fibers. When a liquid binder is used as the binder component, it is preferable to produce a nonwoven fabric by supplying and attaching the binder component to a wet sheet formed with a wire part and drying it with a dryer part. Such liquid binder supply methods include, for example, impregnation method, spray method, Mayer bar method, gravure method, micro gravure method, die method, blade method, micro rod method, air knife method, curtain method, slide method, A known coating method such as a roll method can be exemplified. Of course, the examples are not limited to these examples. In order to increase the strength of the nonwoven fabric, a binder component can be further adhered to the produced nonwoven fabric by an off-machine or the like.

  If the binder component used for this invention is a well-known thing, it will not be restrict | limited at all. For example, in addition to known liquid binders such as acrylic resin, polyimide resin, urethane resin, polyvinyl alcohol, polyacrylamide, water-soluble cellulose, starch, SBR, melamine resin, epoxy resin, phenol resin, meta-aramid fiber, liquid crystal polymer Examples thereof include known thermoplastic fibers such as fibers, thermoplastic polyimide fibers, polypropylene fibers, polyethylene terephthalate fibers, acrylic fibers, polyvinyl alcohol fibers, and polystyrene fibers, and binder fibers such as wood pulp such as KP, GP, and TMP. In the present invention, one type of liquid binder or binder fiber may be used, or a plurality of types may be used. A pigment can also be contained in the binder of the present invention. Examples of the pigment include an inorganic filler described later.

  The component of the nonwoven fabric of the present invention comprises a binder component that binds fibers and inorganic fibers. However, auxiliary additives necessary for the production of wet method nonwoven fabrics, and binding aids for binding inorganic fibers and binder components more strongly ( For example, a small amount of silane coupling agent or the like can be added.

  The prepreg of the present invention is obtained by adhering a resin component to the wet method nonwoven fabric. In this invention, containing an inorganic filler in a resin component is not restrict | limited at all. By including an inorganic filler in the resin component, it is possible to improve the quality of the composite material produced by press-molding this prepreg, such as incombustibility and moisture absorption. The inorganic filler is preferably contained in the resin component in an amount of 30% by mass or more, more preferably 50% by mass or more, and further preferably 60% by mass to 90% by mass.

  Known inorganic pigments can be used as the inorganic filler of the present invention. For example, kaolin, silica, calcium carbonate, calcium silicate, aluminum hydroxide, talc, mica powder, zeolite, mica powder, titanium oxide and the like can be mentioned, and aluminum hydroxide is particularly suitable in terms of nonflammability effect. . At least one inorganic filler can be used. The particle size of the inorganic filler to be used is not particularly limited, but the average particle size is preferably 40 μm or less, and if it is too large, the permeability of the resin component to the nonwoven fabric may be deteriorated.

As the resin of the resin component, known thermoplastic resins and thermosetting resins can be used. In general, thermosetting resins are preferably used. For example, epoxy resins, phenol resins, melamine resins, ureas are preferable. Resins, polyimide resins, cyanate resins, thermosetting polyphenylene oxide resins, and the like are more preferably used.
The method for producing a prepreg of the present invention can be applied by applying a resin component paint using a known method, such as an impregnation method, a spray method, a die method, and a roll method.

The prepreg of the present invention uses the above wet method nonwoven fabric, and the ratio of the adjacent fiber number Z in the thickness direction to the adjacent fiber number X in the planar direction (Z / X) in the cross section of the prepreg is 0.8 or less. The ratio of the number satisfies 5% to 95%. Depending on the (Z / X) value of the wet process nonwoven fabric used, the (Z / X) value of the prepreg is more preferably 0.7 or less, and even more preferably 0.6 or less. Further, the ratio of the number of adjacent fibers is more preferably 10% or more and 75% or less, and further preferably 15% or more and 50% or less.
Further, the observation cross-sectional area for grasping the number of fibers of the prepreg is at least 0.2 mm ² or more, preferably 0.4 mm ² or more. If the observation area is smaller than 0.2 mm ² , the prepreg characteristics may not be fully understood.

The composite material of the present invention is formed by press molding using at least one of the above prepregs. It is good also as a composite material of the type which mixed prepregs other than the said prepreg.
Since the composite material of the present invention uses at least one prepreg of the present invention, the ratio of the number of adjacent fibers Z in the thickness direction and the number of adjacent fibers X in the plane direction in the cross section of the composite material in the layer of that portion The ratio of the number of adjacent fibers having (Z / X) of 0.8 or less satisfies 5% or more and 95% or less. Depending on the (Z / X) value of the wet process nonwoven fabric used, the (Z / X) value in the layer with the composite material is more preferably 0.7 or less, and even more preferably 0.6 or less. The ratio of the number of adjacent fibers is also preferably 10% to 75%, and more preferably 15% to 50%. Further, the observation cross-sectional area for grasping the number of fibers of the composite material is at least 0.2 mm ² or more, preferably 0.4 mm ² or more, and more preferably 1 mm ² or more. If the observation area than 0.2 mm ² is small, there may not be sufficiently grasped properties of the composite.

The composite material of the present invention is preferably a printed wiring board or a decorative board. For this reason, an electrical circuit such as a copper foil can be provided on the surface layer and / or each layer of the composite material, or a composite material in which a decorative sheet surface material is combined.
In the present invention, an auxiliary additive component (for example, a silane coupling agent, a surfactant, etc.) can be added to the resin component including the binder component and the inorganic filler as necessary.

  The present invention will be described more specifically with reference to the following examples. However, the scope of the present invention is not limited to these examples. In Examples, “%” and “parts” indicate “% by mass” and “parts by mass” unless otherwise specified.

<Example 1>
It is a nonionic surfactant for fibers adjusted to a mass ratio of E glass fiber chop with round cross-section fiber diameter φ13μm fiber length 9mm and E glass fiber chop with round cross-section fiber diameter φ6μm fiber length 3mm. Polyethylene glycol stearate (Emanon 3299, manufactured by Kao Corporation) was mixed at 1% to fiber, followed by polyethyleneimine (trade name: Epomin P-1000 (stock solution 30%, manufactured by Nippon Shokubai Co., Ltd.) to 0.05% fiber. The mixture was stirred in water at a fiber concentration of 0.02% using a three-one motor, and it was confirmed by visual observation that this fiber dispersion was free of bundled fibers. A molecular anionic polyacrylamide (Sumifloc FA40H, manufactured by Sumitomo Chemical Co., Ltd.) 0.1% solution is stirred at a ratio of 0.5 part with respect to 100 parts of the dispersion to focus the fibers. A fiber dispersion containing bundles of bundled fibers was prepared, and the fiber dispersion containing bundles of bundled fibers was wet-made by a square handmaking machine using a plastic wire having a number of meshes of 80 mesh. Subsequently, an acrylic emulsion (A-104, manufactured by Toagosei Co., Ltd.) was attached as a binder component to the obtained wet sheet by spraying, and dried for 10 minutes with a dryer at 160 ° C., basis weight 100 g / m ² , amount of binder 10% of the nonwoven fabric was obtained, and the thickness and bulk density of the nonwoven fabric were measured at 50 kPa based on JIS P-8118. The texture was judged by visual evaluation. embedded in, cut out the non-woven fabric of cross with a microtome, and observing the cross-section 0.5 mm ² of the nonwoven fabric by SEM (backscattered electron image), for each adjacent fiber bundle (Z / X) value and an adjacent number of fibers Aggregate Was determined percentage in number contained in the nonwoven fabric cross section adjacent the number of fibers. The results are shown in Table 1 for each (Z / X) value.

<Example 2>
It is a nonionic surfactant for fibers adjusted to a mass ratio of E glass fiber chop with round cross-section fiber diameter φ13μm fiber length 9mm and E glass fiber chop with round cross-section fiber diameter φ6μm fiber length 3mm. Polyethylene glycol stearate (Emanon 3299, manufactured by Kao Corporation) was mixed at 1% to fiber, followed by polyethyleneimine (trade name: Epomin P-1000 (stock solution 30%, manufactured by Nippon Shokubai Co., Ltd.) to 0.02% to fiber. The mixture was stirred in water at a fiber concentration of 0.02% using a three-one motor, and it was confirmed by visual observation that this fiber dispersion was free of bundled fibers. A molecular anionic polyacrylamide (Sumifloc FA40H, manufactured by Sumitomo Chemical Co., Ltd.) 0.1% solution is stirred at a ratio of 0.5 part with respect to 100 parts of the dispersion to focus the fibers. A fiber dispersion containing bundles of bundled fibers was prepared, and the fiber dispersion containing bundles of bundled fibers was wet-made by a square handmaking machine using a plastic wire having a number of meshes of 80 mesh. Subsequently, an acrylic emulsion (A-104, manufactured by Toagosei Co., Ltd.) was attached as a binder component to the obtained wet sheet by spraying, and dried for 10 minutes with a dryer at 160 ° C., basis weight 100 g / m ² , amount of binder 10% nonwoven fabric was obtained, and the thickness and bulk density of the nonwoven fabric were measured at 50 kPa based on JIS P-8118. Paper quality was measured in the same manner as in Example 1, and the results are shown in Table 1.

<Example 3>
E glass fiber chop with a circular cross-section shape fiber diameter of φ6μm and fiber length of 3mm is mixed with polyethylene glycol stearate (Emanon 3299, manufactured by Kao Corporation), a nonionic surfactant, at 1% of the fiber, and the fiber concentration is measured using a three-one motor. Stir in water at 0.02%. Thereafter, an anionic water-soluble polymer, an anionic water-soluble polymer, an anionic polyacrylamide (Sumifloc FA40H, manufactured by Sumitomo Chemical Co., Ltd.) 0.1% solution was mixed at a ratio of 0.2 part to 100 parts of the dispersion. A fiber dispersion was prepared. It was confirmed by visual observation that this fiber dispersion was free of bound fibers. In this component dispersion, 0.2 part of a polyethyleneimine 0.0005% solution (trade name: Epomin P-1000 (stock solution 30%, manufactured by Nippon Shokubai Co., Ltd.)) is added and stirred to bundle the fibers, and the fiber dispersion contains a bundle of bundled fibers. The fiber dispersion containing the bundle of bundled fibers was wet-made by a square hand-making machine using a plastic wire with a wire mesh number of 80 mesh, and then the resulting wet sheet was sprayed. Acrylic emulsion (A-104, manufactured by Toagosei Co., Ltd.) was attached as a binder component and dried for 10 minutes in a dryer at 160 ° C. to obtain a nonwoven fabric having a basis weight of 100 g / m ² and a binder amount of 10%. The thickness and bulk density of the resulting nonwoven fabric were measured at 50 kPa based on JIS P-8118. Paper quality was measured in the same manner as in Example 1, and the results are shown in Table 1.

<Comparative Example 1>
The same examination as in Example 1 was conducted except that polyethyleneimine was not added. The results are shown in Table 1.
<Comparative example 2>
The same examination as in Example 2 was performed except that polyethyleneimine was not added. The results are shown in Table 1.
<Comparative Example 3>
The same examination as in Example 1 was conducted except that polyethyleneimine was not added. The results are shown in Table 1.

＜実施例４＞
レゾール型フェノール樹脂（固形分50％）40部に平均粒径5μｍの水酸化アルミニウム50部、平均粒径20μｍの雲母粉30部、メタノール20部を混合した樹脂成分塗料を実施例１の不織布に付着量が固形分で1000g/m²（固形分）になるように含浸し、乾燥してプリプレグを得た。このプリプレグを包埋樹脂にて包埋し、ミクロトームにてプリプレグの断面を削り出し、ＳＥＭ（反射電子像）にてプリプレグの断面0.5mm²を観察し、隣接繊維束毎の（Ｚ／Ｘ）値と隣接繊維本数を集計し、各（Ｚ／Ｘ）値に対応する隣接繊維本数のプリプレグ断面中に含まれる本数割合を求めた。結果を表２に示す。

<Example 4>
A resin component paint obtained by mixing 40 parts of a resol type phenolic resin (solid content 50%) with 50 parts of aluminum hydroxide having an average particle diameter of 5 μm, 30 parts of mica powder having an average particle diameter of 20 μm, and 20 parts of methanol is used as the nonwoven fabric of Example 1. The prepreg was obtained by impregnation so that the adhesion amount was 1000 g / m ² (solid content) in solid content and dried. Were embedded prepreg at embedding resin, shaving prepreg cross section with a microtome, SEM observation of the cross-section 0.5 mm ² of the prepreg at (backscattered electron image), for each adjacent fiber bundle (Z / X) The values and the number of adjacent fibers were tabulated, and the ratio of the number of fibers included in the prepreg cross section of the number of adjacent fibers corresponding to each (Z / X) value was determined. The results are shown in Table 2.

<Example 5>
A resin component paint in which 80 parts of a resole phenolic resin (solid content 50%) is mixed with 60 parts of aluminum hydroxide having an average particle size of 5 μm is attached to the nonwoven fabric of Example 2 at a solid content of 1000 g / m ² (solid content). To obtain a prepreg. The properties of the prepreg obtained in the same manner as in Example 4 were measured, and the results are shown in Table 2.

<Example 6>
Example 3 A resin component paint obtained by mixing 40 parts of epoxy resin (solid content 50%), 0.15 part of phenylimidazole, 50 parts of aluminum hydroxide having an average particle diameter of 5 μm, 30 parts of mica powder having an average particle diameter of 20 μm and 20 parts of methyl ethyl ketone The nonwoven fabric was impregnated with a solid content of 1000 g / m ² and dried to obtain a prepreg. The properties of the prepreg obtained in the same manner as in Example 4 were measured, and the results are shown in Table 2.

<Comparative example 4>
The same examination as in Example 4 was performed except that the nonwoven fabric of Comparative Example 1 was used. The results are shown in Table 2.
<Comparative Example 5>
The same examination as in Example 5 was performed except that the nonwoven fabric of Comparative Example 2 was used. The results are shown in Table 2.
<Comparative Example 6>
The same examination as in Example 6 was performed except that the nonwoven fabric of Comparative Example 3 was used. The results are shown in Table 2.

＜実施例７＞
坪量64g/m²のグラビア印刷された紙にメラミン樹脂を固形分で130g/m²付着含浸乾燥させた含浸紙に実施例４のプリプレグを７枚重ね、150℃、80kgf/m²、20分間の条件でプレス成形し、複合材料である化粧板を作成した。得られた複合材料を、ミクロトームにて断面を削り出し、ＳＥＭ（反射電子像）にて不織布部部分の断面0.5mm²を観察し、隣接繊維束毎の（Ｚ／Ｘ）値と隣接繊維本数を集計し、各（Ｚ／Ｘ）値に対応する隣接繊維本数の不織布部分の断面中に含まれる本数割合を求めた。結果を表３に示す。

<Example 7>
Basis weight 64 g / m ² of the gravure printing melamine resin paper piled seven to 130 g / m ² adhered impregnated dried prepreg of Example 4 in the impregnated paper was in ^{solid, 150 ℃, 80kgf / m 2} , 20 It was press-molded under the condition of minutes, and a decorative board as a composite material was prepared. The resulting composite material, cut out a section with a microtome, and observing the cross-section 0.5 mm ² of the nonwoven fabric portion at SEM (backscattered electron image), for each adjacent fiber bundle (Z / X) value and an adjacent number of fibers And the number ratio contained in the cross section of the nonwoven fabric portion of the number of adjacent fibers corresponding to each (Z / X) value was obtained. The results are shown in Table 3.

<Example 8>
The same examination as in Example 7 was performed except that the prepreg of Example 5 was used. The results are shown in Table 3.

<Example 9>
A resin component paint mixed with 40 parts of epoxy resin (solid content 50%) and 0.15 part of phenylimidazole is impregnated on a glass cloth of 200 g / m ^{2 so that} the amount of adhesion is 160 g / m ² in solid content and dried. A glass cloth prepreg was obtained. Two glass cloth prepregs were stacked, and three prepregs of Example 6 were stacked thereon, and press molded under conditions of 150 ° C., 80 kgf / m ² , 60 minutes to prepare a composite material. The properties of this composite material are shown in Table 3.

<Comparative Example 7>
The same examination as in Example 7 was performed except that the prepreg of Comparative Example 4 was used. The results are shown in Table 3.
<Comparative Example 8>
The same examination as in Example 7 was performed except that the prepreg of Comparative Example 5 was used. The results are shown in Table 3.
<Comparative Example 9>
The same examination as in Example 9 was performed except that the prepreg of Example 6 was used. The results are shown in Table 3.

Non-woven fabric cross section

Explanation of symbols

(1) to (3) Examples of adjacent fiber bundles

Claims (11)

A wet process nonwoven fabric comprising a binder component that binds inorganic fibers and fibers, wherein the ratio of the number of adjacent fibers to the total number of fibers in the cross section of the nonwoven fabric is 5% to 95%. 2. The wet method nonwoven fabric according to claim 1, wherein a ratio (Z / X) of the number of adjacent fibers in the thickness direction Z to the number of adjacent fibers in the plane direction (Z / X) of the adjacent fibers is 0.8 or less. The wet nonwoven fabric according to claim 1 or 2, wherein the inorganic fiber has an average fiber diameter of 4 to 20 µm and an average fiber length of 1 to 25 mm. The wet method nonwoven fabric according to any one of claims 1 to 3, wherein the inorganic fiber is a glass fiber. The density of the wet method ^{nonwoven, 0.10g / cm 3 ~0.25g / cm} 3 a wet method nonwoven fabric according to any one of claims 1 to 4, characterized in that. The wet process nonwoven fabric according to any one of claims 1 to 5, wherein the binder amount is 3% by mass to 25% by mass. A prepreg comprising a resin component attached to the wet method nonwoven fabric according to claim 1. The ratio of the number of adjacent fibers in which the ratio (Z / X) of the number of adjacent fibers Z in the thickness direction and the number X of adjacent fibers in the planar direction in the cross section of the prepreg is 0.8 or less is 5% or more and 95% or less. The prepreg according to claim 7, wherein the prepreg is characterized. A composite material obtained by press molding using at least one prepreg according to claim 8. A layer in which the ratio of the number of adjacent fibers (Z / X) between the number of adjacent fibers Z in the thickness direction and the number X of adjacent fibers in the planar direction is 0.8 or less in the cross section of the composite material is 5% or more and 95% or less. The composite material according to claim 9, comprising: The composite material according to claim 10, wherein the composite material is a printed wiring board or a decorative board.

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