JP4980107B2 - Substrate for resin reinforcement and manufacturing method thereof - Google Patents

Description

  The present invention relates to a non-woven fabric that is excellent in heat resistance, non-hygroscopicity, and adhesiveness with an impregnating resin, and useful as a substrate for resin reinforcement such as a printed circuit board and an abrasive carrier material, and a method for producing the same.

Conventionally, woven fabrics and non-woven fabrics made of glass fibers have been widely used as a substrate for resin reinforcement in printed boards. However, in the case of glass fiber, there are problems such as high dielectric constant, large specific gravity, and powder falling off during cutting.
A woven fabric and a nonwoven fabric made of aramid fibers instead of glass fibers have been proposed (see, for example, Patent Document 1). However, aramid fibers have a high moisture absorption rate and low reliability for dielectric properties. Moreover, when manufacturing paper and nonwoven fabric made of aramid fibers, there is a problem that it is difficult to reduce the thickness because it can only be obtained by a papermaking method.

  A molten liquid crystal-forming wholly aromatic polyester non-woven fabric has been proposed that solves the above problems and has low dielectric properties, which is a required performance of substrates for high-speed and large-capacity communication devices in recent years (see, for example, Patent Document 2). ). However, melted liquid crystal-forming wholly aromatic polyesters have the advantage of excellent chemical resistance. On the other hand, when they are used as reinforcing substrates for resin laminates, they have poor adhesion to the resin to be impregnated, and the resin and fiber There is a problem that the interfacial peeling and the reinforcing property cannot be sufficiently obtained.

In order to solve such a problem, plasma discharge treatment in which a functional group is introduced to the surface of the wholly aromatic polyester has been proposed (see, for example, Patent Document 3).
However, in the method of Patent Document 3, sufficient effects cannot be obtained in a short time, and batch processing is required to obtain sufficient effects, which is disadvantageous in terms of mass productivity and cost.

JP 62-011289 A Japanese Patent Laid-Open No. 2002-064254 JP 2004-207333 A

  The object of the present invention has been made in view of the above problems, and provides a resin-reinforced base material that is excellent in non-hygroscopicity, heat resistance, and adhesiveness with an impregnating resin and can be manufactured at low cost. It is in.

  As a result of diligent investigations to solve such problems, the inventors of the present invention obtained a non-woven fabric obtained by heat-treating a non-woven fabric made of a molten liquid crystal-forming wholly aromatic polyester polymer in the presence of moisture at a predetermined moisture content. Was found to be excellent, and the adhesiveness with the resin to be impregnated was significantly improved, and the present invention was completed.

That is, the present invention comprises a substantially continuous filament having a melt liquid crystal-forming wholly aromatic polyester having a melt viscosity at 310 ° C. of 20 Pa · s or less and an average fiber diameter of 1 to 15 μm, The glass transition point by dynamic viscoelasticity measurement after heat treatment for 3 to 80 hours at a temperature of melting point −40 ° C. or higher and melting point + 20 ° C. or lower of molten liquid crystal forming wholly aromatic polyester in the presence of water at a rate of 50 ppm to 100 ppm is 120. ℃ nonwoven, characterized in that more than is a resin reinforced molded body used as the reinforcing material, good Mashiku is a resin reinforced molded article using the above nonwoven fabric comprising manufactured by a melt blow method as reinforcement.

  The nonwoven fabric of the present invention has excellent water resistance, and the adhesiveness with the resin to be impregnated is remarkably improved.

  The molten liquid crystal-forming wholly aromatic polyester used for the nonwoven fabric in the present invention is a resin excellent in heat resistance and chemical resistance. The molten liquid crystal-forming wholly aromatic polyester referred to in the present invention is an aromatic polyester that exhibits optical anisotropy (liquid crystallinity) in the molten phase. For example, a sample is placed on a hot stage and heated in a nitrogen atmosphere. It can be recognized by observing the transmitted light. The melt-anisotropic polyester is composed mainly of repeating structural units of aromatic diol, aromatic dicarboxylic acid, and aromatic hydroxycarboxylic acid. For example, those composed of combinations of repeating structural units shown below are preferable.

Among these, as the molten liquid crystal-forming wholly aromatic polyester used in the present invention, a configuration mainly composed of parahydroxybenzoic acid and 6-hydroxy-2-naphthoic acid, or parahydroxybenzoic acid and 6-hydroxy A configuration in which -2-naphthoic acid, terephthalic acid, and biphenol are the main components is preferable.
The melted liquid crystal-forming wholly aromatic polyester has the functions of the present invention as required by adding additives such as colorants, inorganic fillers, antioxidants, ultraviolet absorbers, and thermoplastic elastomers as necessary. You may add in the range which does not inhibit.

The melted liquid crystal-forming wholly aromatic polyester used in the present invention needs to have a melt viscosity at 310 ° C. of 20 Pa · s or less, preferably 15 Pa · s or less, more preferably 12 Pa · s or less. . When the melt viscosity exceeds 20 Pa · s, it is not preferable because it is difficult to make ultrafine fibers, or the occurrence of oligomers during polymerization or the occurrence of troubles during polymerization or granulation.
On the other hand, since fiberization is difficult even when the melt viscosity is too low, the melt viscosity at 310 ° C. is preferably 5 Pa · s or more.

Next, examples of the manufacturing method (spinning method) of the melt liquid crystal-forming wholly aromatic polyester nonwoven fabric referred to in the present invention include a flash spinning method, a melt blowing method, etc., but it is relatively easy to manufacture a nonwoven fabric composed of ultrafine fibers. A nonwoven fabric produced by a melt-blowing method is preferable because a solvent is not required at the time of spinning and the influence on the environment can be minimized.
In the case of producing by the melt blowing method, a conventionally known melt blowing apparatus can be used as the spinning apparatus. The spinning conditions are preferably a spinning temperature of 310 to 360 ° C., a hot air temperature (primary air temperature) of 310 to 380 ° C., and an air amount of 10 to 50 Nm ³ per 1 m of the nozzle length. Moreover, the average fiber diameter of the fiber which comprises the nonwoven fabric of this invention manufactured in this way needs to be 1-15 micrometers, it is preferable that it is 2-13 micrometers, and it is more 3-11 micrometers. preferable. If the average fiber diameter is less than 1 μm, fluff is likely to be formed and a fiber lump is easily formed. On the other hand, if it exceeds 15 μm, the formation becomes rough, which is not preferable.
In addition, in this invention, an average fiber diameter shows the average value of the value which carried out magnified photography of the nonwoven fabric with the scanning electron microscope, and measured arbitrary 100 fiber diameters.

The basis weight of the melted liquid crystal-forming wholly aromatic polyester nonwoven fabric used for the nonwoven fabric of the present invention is not particularly limited and can be appropriately adjusted according to the required performance, but it is 5 in terms of insulation and workability. It is preferable that it is -300 g / m < ² >. If the basis weight is less than 5 g / m ² , the formation and the denseness are lowered and sufficient insulation performance cannot be obtained. If the basis weight is more than 300 g / m ² , the heat transfer is lowered in the subsequent laminating process, and the processing speed is remarkably increased. Will be reduced.

  The molten liquid crystal-forming wholly aromatic polyester nonwoven fabric of the present invention needs to have a glass transition temperature of 120 ° C. or higher by dynamic viscoelasticity measurement, preferably 125 ° C. or higher, more preferably 130 ° C. or higher and 180 ° C. or lower. When the glass transition temperature by dynamic viscoelasticity measurement is less than 120 ° C, for example, when the nonwoven fabric of the present invention is used as a reinforcing substrate for printed circuit boards, boiling or saturated steam pressurization (one of long-term reliability evaluations) In the evaluation of solder heat resistance after forced humidification treatment (conditions: 121 ° C., 100% RH, 2 atm), etc. (conditions: immersed in a solder bath at 260 to 288 ° C.) Water penetration causes problems such as water vaporization, volume expansion, and swelling when immersed in a solder bath.

Molten liquid crystal forming wholly aromatic polyester nonwoven fabric having a glass transition temperature of 120 ° C. or higher by dynamic viscoelasticity measurement is a melting point of molten liquid crystal forming wholly aromatic polyester in a high temperature gas having a water content of 50 ppm or higher. By performing heat treatment at a temperature of + 20 ° C. or lower for 3 to 80 hours, a crosslinked structure is formed between the fibrils in the fiber, so that the glass transition temperature becomes 120 ° C. or higher by dynamic viscoelasticity measurement.
Furthermore, by performing the heat treatment under the above conditions, the functional group is expressed by hydrolysis of the fiber surface layer, and when the resin-reinforced molded article is produced, the adhesiveness with the resin to be impregnated is remarkably improved.
Here, in the heat treatment with a water content of less than 50 ppm, the glass transition point is not increased and the water resistance is not improved, and when the resin-reinforced molded article is produced, the adhesiveness with the resin to be impregnated is not sufficiently obtained.
Examples of the moisture application method include a method in which a combustion gas such as propane is supplied and the moisture content is controlled by the amount of combustion, a method in which steam is supplied into the heating medium, and the moisture content is controlled by the supply amount. . Here, examples of the gas used as the heating medium include a mixed gas such as nitrogen, oxygen, argon, and carbon dioxide, or air. However, oxygen or air is more preferable in terms of cost and an effect of improving the adhesion to the resin. The heat treatment may be under tension or without tension depending on the purpose. When heat treatment is performed at a temperature lower than the melting point of the molten liquid crystal-forming wholly aromatic polyester of −40 ° C., the fiber surface modification does not proceed sufficiently, and the heat treatment temperature of the molten liquid crystal-forming wholly aromatic polyester When the melting point exceeds + 20 ° C., the polymer softens, the fiber starts to melt, and a part of the sheet is formed into a film, which causes a problem in the resin impregnation property in a later process. Further, before heat treatment in the water-containing heating medium, the entanglement point of the melted liquid crystal-forming wholly aromatic polyester fiber and the orientation of the fiber itself are promoted in an inert gas such as nitrogen and carbon dioxide that does not contain moisture, and the nonwoven fabric It is also possible to improve the strength.
Further, even if the heat treatment is performed under the above conditions, if the heat treatment time is less than 3 hours, the heat treatment is insufficient and a crosslinked structure is not sufficiently formed between the fibrils in the fiber. On the other hand, when it exceeds 80 hours, the deterioration is rather advanced and the strength is lowered, or there is a problem in terms of productivity. A more preferable heat treatment time condition is 4 to 70 hours, and more preferably 5 to 60 hours.

  The nonwoven fabric obtained in this way is impregnated with a thermosetting resin such as epoxy resin, BT (bismaleimide / triazine) resin, PPE (polyphenylene ether) resin, and then cured by press molding. In addition, a resin-reinforced molded article excellent in low dielectric properties and non-water absorption can be obtained.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited by an Example. In addition, in this invention, the glass transition point by dynamic viscoelasticity means what was measured with the following measuring methods.

[Glass transition temperature by dynamic viscoelasticity in ° C]
Using a Shimadzu Corporation dynamic viscoelasticity measuring device ("Ryo Spectral DVE-V4" manufactured by UBM Co., Ltd.), the temperature was increased at a rate of 10 ° C / minute, the frequency was 10 Hz, and the automatic static load method was used. Tan δ = E ″ / E ′ is calculated from the ratio between the storage elastic modulus (E ′) and the loss elastic modulus (E ″), and a temperature (° C.)-Tan δ curve as shown in FIG. The point (peak temperature) was taken as the glass transition point.

[Reference Example 1]
130 parts by mass of a polyfunctional epoxy resin [“YL6046B80 (registered trademark)” manufactured by Japan Epoxy Resin Co., Ltd.] and 70 parts by mass of a novolac type curing agent [“YLH129B65 (registered trademark)” manufactured by Japan Epoxy Resin Co., Ltd.] and an imidazole type curing accelerator [ "EM124 (registered trademark)" manufactured by Japan Epoxy Resin Co., Ltd.] and 0.3 part by mass of methyl ethyl ketone were mixed to prepare a matrix resin (varnish).

[Reference Example 2]
The varnish produced in Reference Example 1 was impregnated into the laminates of Examples 1-2 and Comparative Examples 1-3 described later, and dried at 130 ° C. for 10 minutes to produce a prepreg with a resin impregnation amount of 65 mass%. Four prepregs were stacked, placed between 1 mm thick stainless steel plates, and heated under pressure under a pressure of 40 kgf / cm ² and a temperature of 180 ° C. for 1 hour to produce a resin laminate.

[Evaluation of adhesion with impregnating resin]
The resin laminate produced in Reference Example 2 was boiled in 100 ° C. boiling water for 8 hours to forcibly infiltrate the fine bubbles contained in the resin laminate. Thereafter, the adhered moisture was removed at room temperature, and the treated resin laminate was immersed in a solder bath heated to 260 ° C. for 30 seconds, and evaluated by the presence or absence of swelling of the resin laminate due to the expansion of permeated moisture. When no swelling occurs, it is evaluated that the adhesion between the impregnating resin and the nonwoven fabric is good.

[Example 1]
(1) Molten liquid crystal-forming wholly aromatic polyester (polyplastics Co., Ltd.) comprising a copolymer of parahydroxybenzoic acid and 6-hydroxy-2-naphthoic acid and having a melt viscosity at 310 ° C. of 15 Pa · s. "Vectra-L") is extruded from a twin screw extruder and supplied to a melt blown nonwoven fabric manufacturing apparatus having a nozzle with a width of 1 m and a hole count of 1000, with a single hole discharge rate of 0.3 g / min, a resin temperature of 310 ° C, and a hot air temperature A nonwoven fabric having an average fiber diameter of 11 μm and a basis weight of 40 g / m ² was obtained under the conditions of 310 ° C. and an air amount of 20 Nm ³ per nozzle length of 1 m.
(2) Next, the nonwoven fabric obtained in the above (1) was treated at 270 ° C. for 6 hours in a steam / air mixed gas having a water content of 100 ppm. The glass transition point of this nonwoven fabric determined by dynamic viscoelasticity was 130 ° C.
(3) Using the nonwoven fabric obtained in (2) above, a resin laminate was produced by the method of Reference Example 2 and evaluated for adhesion to the impregnated resin. The resulting resin laminate was swollen. Was not generated, and the adhesion between the impregnating resin and the nonwoven fabric was good.

[Example 2]
In the heat treatment conditions of Example 1 (2), a nonwoven fabric and a resin laminate were obtained in the same manner as in Example 1 except that the water application method used propane combustion gas instead of steam.
The glass transition point of the obtained nonwoven fabric by dynamic viscoelasticity measurement is 130 ° C., and further, no swelling occurs in the resin laminate produced by the method of Reference Example 2 using the nonwoven fabric, and the impregnated resin and Adhesiveness with the nonwoven fabric was good.

[Comparative Example 1]
(1) Molten liquid crystal-forming wholly aromatic polyester (polyplastics Co., Ltd.) comprising a copolymer of parahydroxybenzoic acid and 6-hydroxy-2-naphthoic acid and having a melt viscosity at 310 ° C. of 15 Pa · s. "Vectra-L") is extruded from a twin screw extruder and supplied to a melt blown nonwoven fabric manufacturing apparatus having a nozzle with a width of 1 m and a hole count of 1000, with a single hole discharge rate of 0.3 g / min, a resin temperature of 310 ° C, and a hot air temperature A nonwoven fabric having an average fiber diameter of 11 μm and a basis weight of 40 g / m ² was obtained under the conditions of 310 ° C. and an air amount of 20 Nm ³ per nozzle length of 1 m. This nonwoven fabric was not heat-treated in an atmosphere having a moisture content of 50 ppm or more.
(2) The glass transition point by dynamic viscoelasticity measurement of the nonwoven fabric of (1) was 110 ° C. Furthermore, when the resin laminate was produced by the method of Reference Example 2 using the nonwoven fabric and the adhesion with the impregnated resin was evaluated, swelling occurred, and the adhesion between the impregnated resin and the nonwoven fabric was poor. .

[Comparative Example 2]
(1) A melt liquid crystal-forming wholly aromatic polyester comprising a copolymer of parahydroxybenzoic acid and 6-hydroxy-2-naphthoic acid and having a melt viscosity at 310 ° C. of 15 Pa · s is obtained from a twin screw extruder. Extruded and supplied to a melt blown nonwoven fabric manufacturing apparatus having a nozzle with a width of 1 m and a number of holes of 1000, with a single-hole discharge rate of 0.3 g / min, a resin temperature of 310 ° C., a hot air temperature of 310 ° C., and an air amount of 20 Nm ³ per nozzle length. Under the conditions, a nonwoven fabric having an average fiber diameter of 11 μm and a basis weight of 40 g / m ² was obtained.
(2) When the non-woven fabric obtained in the above (1) was heat-treated in air having a water content of 15 ppm at 270 ° C. for 6 hours, the glass transition point was 110 ° C.
Using this nonwoven fabric, a resin laminate was produced by the method of Reference Example 2 and the adhesion with the impregnated resin was evaluated. As a result, swelling occurred, and the adhesion between the impregnated resin and the nonwoven fabric was poor. .

  The nonwoven fabric obtained by the production method of the present invention and the resin-molded reinforcing body using the nonwoven fabric are not only insulating materials that require high insulation performance and long-term reliability, such as printed circuit board applications, but also cushion materials for high-temperature presses, heat insulation It is also useful as a material.

The figure which shows an example of the temperature (degreeC) -tan-delta curve by the dynamic viscoelasticity measurement of the nonwoven fabric of this invention.

Claims (2)

It consists of a substantially continuous filament having a melt liquid crystal-forming wholly aromatic polyester having a melt viscosity at 310 ° C. of 20 Pa · s or less and an average fiber diameter of 1 to 15 μm, and has a moisture content of 50 ppm or more and 100 ppm or less. In the presence of water, the glass transition point by dynamic viscoelasticity measurement after heat treatment for 3 to 80 hours at a temperature of melting point −40 ° C. or higher and melting point + 20 ° C. or lower of molten liquid crystal forming wholly aromatic polyester is 120 ° C. or higher. A resin-reinforced molded article using a non-woven fabric characterized by the above as a reinforcing material . Reinforcing resin molded body used as the stiffener formed by produced according to claim 1, wherein the nonwoven fabric main Rutoburo method.

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