JP3762960B2 - Method for producing flat poly-p-phenylene diphenyl ether terephthalamide fiber - Google Patents

Description

繊維Ａ：ＰＰＤＴ繊維（帝人製、商品名：テクノーラ、繊維径１．５ｄ、繊維長３．０ｍｍ）
繊維Ｂ：ポリ−ｐ−フェニレンテレフタラミド繊維（東レ・デュポン製、商品名：ケブラー、繊維径１．５ｄ、繊維長３．０ｍｍ）
【００４１】
【発明の効果】
本発明の製造方法により、扁平ＰＰＤＴ繊維を簡便、効率的、かつ安価に製造することができる。この扁平ＰＰＤＴ繊維は、通常の円形断面を有するパラ系アラミド繊維に比べ、不織布としたときの引張強度、地合いが良好であり、ピンホールも少なく、薄物の積層板用不織布を得るのに最適な繊維である。
【図面の簡単な説明】
【図１】扁平化の機構を示す図である。
【図２】扁平化の処理前のＰＰＤＴ繊維の顕微鏡写真である。
【図３】実施例１で調製した部分扁平化ＰＰＤＴ繊維の顕微鏡写真である。
【図４】実施例２調製された、全体的に扁平化されたＰＰＤＴ繊維の顕微鏡写真である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing poly-p-phenylene diphenyl ether terephthalamide fibers (hereinafter simply referred to as “PPDT”) in which some or all of the fibers are flattened. More specifically, the present invention relates to a method for producing a flat para-aramid fiber suitable for producing a non-woven fabric having high strength even at a low surface area, in a simple, efficient and inexpensive manner.
[0002]
[Prior art]
Due to recent demands for light and thin electronic devices, there is an increasing demand for light and thin electronic components and printed wiring boards that constitute electronic devices. In order to meet this demand, development of high-density packaging technology has been urgently done, and multilayer printed wiring boards using the build-up method have become mainstream, but as an insulating layer for further weight reduction and miniaturization. Thinning of 50 μm or 30 μm is required.
[0003]
Currently, the build-up method that has become the mainstream is a method in which a glass cloth epoxy resin laminate is used as a core substrate, and a copper foil with resin is laminated on one or both sides. Development of a thin prepreg is desired because the layer thickness is inferior and the strength is weak because there is no reinforcing material. A glass cloth is generally used as a prepreg base material, but a nonwoven fabric using organic fibers is desired from the viewpoint of lightness, surface smoothness, suitability for laser processing, low dielectric constant, and the like.
[0004]
A typical example of an organic fiber nonwoven fabric that has been put to practical use as a substrate for multilayer boards is an aramid nonwoven fabric. In particular, since para-aramid fibers have a negative thermal expansion coefficient in the axial direction, they are effective in reducing the thermal expansion coefficient in the plane direction of the laminate. The aramid nonwoven fabric for laminates currently in practical use includes a nonwoven fabric obtained by blending a thermosetting resin binder or a meta-aramid pulp as a binder component with a para-aramid fiber and heat-calendering it.
However, when these non-woven fabrics are made thin (low US basis weight) in order to achieve the above-mentioned thinning, the strength decreases greatly, the process strength of the prepreg manufacturing process cannot be obtained, the unevenness of the texture is large, There were problems, such as increasing.
[0005]
As a method for solving the above-described decrease in strength, it is conceivable to simply increase the amount of thermosetting resin binder or meta-aramid pulp.
However, there are appropriate values for the amount of resin binder and pulp added, and if the amount is too large, the strength decreases. Moreover, in these methods, para-aramid fibers are relatively reduced, and the effect of reducing the thermal expansion coefficient described above is reduced. In addition, the improvement of unevenness of formation and the effect of reducing pinholes cannot be expected. Further, meta-aramid pulp is not preferred because it has a higher moisture absorption rate than para-aramid fiber, and therefore the moisture absorption rate of the laminate is increased, which adversely affects electrical characteristics, solder heat resistance, and the like.
[0006]
On the other hand, a method of blending para-aramid pulp in fibril form is also conceivable, but if the pulp is blended up to about 20%, there is an effect of improving the strength of the nonwoven fabric, but the thinning is achieved. The effect cannot be expected.
JP-A-5-163610 discloses a para-aromatic polyamide fiber having a flat cross section. However, this technique involves spinning through a specially shaped die having a flat cross section, and in order to maintain the flat shape, it is necessary to slow down the take-up speed of the coagulated yarn, resulting in poor productivity. is there.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to provide a simple, efficient and inexpensive method for producing a flattened para-aramid fiber having a shape suitable for obtaining a high-strength non-woven fabric even at a low weight.
[0008]
[Means for Solving the Problems]
When the present inventors flatten poly-p-phenylene diphenyl ether terephthalamide (PPDT) fibers, they can be easily flattened by pressing the PPDT fibers between spherical surfaces. As a result, it was found that a nonwoven fabric excellent in tensile strength and texture and having few pinholes can be obtained as compared with a nonwoven fabric using a fiber having a normal circular cross section, and the present invention has been completed. That is, the present invention relates to a method of manufacturing a PPDT fiber in which part or all of the fiber is flattened, and the flattening is performed by pressing the PPDT fiber between spherical surfaces. .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
The PPDT fiber used in the present invention is a kind of para-aromatic polyamide fiber, and has the following chemical structure.
[0010]
—NH—Ar ₁ —NHCO—Ar ₂ —CO—
In the formula, Ar ₁ is a p-phenylene group or a p-diphenyl ether group, and Ar ₂ is a p-phenylene group. However, para-type aromatic polyamide fibers in which Ar ₁ is a p-phenylene group alone, such as Kevlar (manufactured by Toray DuPont), are not included. The p-phenylene group or p-diphenyl ether group may have a substituent on the phenyl group. As such a substituent, for example, a halogen atom, a lower alkyl group (for example, a methyl group, an ethyl group, etc.) and the like can be preferably exemplified.
[0011]
In Ar ₁ , the ratio of the p-phenylene group to the p-diphenyl ether is, for example, 1: 1.
Examples of PPDT fibers used in the present invention include Teijin Technora.
In addition, when poly-p-phenylene terephthalamide fiber (for example, Kevlar) is used as the para-aramid fiber, it is easily fibrillated (micronized) by flattening by pressing between spheres, especially by flattening by sand mill treatment. It is difficult to obtain flat fibers. The cause of this is not clear, but is presumed to be due to the difference in the fibril structure constituting the fiber.
[0012]
The fiber diameter and fiber length of the PPDT fiber are not particularly limited. However, if the fiber diameter is too large, the number of fibers in the same US basis weight will decrease, leading to deterioration of tensile strength and texture. . On the other hand, if the fiber diameter is too thin, problems such as flattening treatment described later, in particular, dispersibility in a suspension in a sand mill are likely to deteriorate, and fibers are entangled during the sand mill treatment. In addition, as the fiber diameter becomes thinner, the productivity of the fiber deteriorates and becomes expensive, which causes a cost increase.
The PPDT fiber is preferably 0.5 to 5 denier (d), particularly preferably 0.5 to 2 denier.
[0013]
Even when the fiber length of the PPDT fiber is too long, there is a problem that dispersibility in a suspension in a sand mill, which will be described later, is likely to deteriorate, or fibers are entangled during the sand mill treatment. On the other hand, if the fiber length is too short, the number of intersections per fiber will decrease, leading to a decrease in strength of the nonwoven fabric. . Therefore, the fiber length of the PPDT fiber is, for example, 1 to 10 mm, preferably 2 to 6 mm. Within this range, those having different fiber diameters or fiber lengths may be mixed and used.
[0014]
The flattening used in the present invention is achieved by pressing between spherical surfaces. For example, when a PPDT fiber having a circular cross section is processed in a state where the sphere or bead is moved or agitated in a container containing a large number of spheres or beads, the PPDT fiber is pressed between the spherical surfaces of the spheres or beads. And flattened. The degree and frequency of pressing at this time vary depending on the size (diameter) of the sphere accommodated in the container, the filling rate, the processing time, the degree of stirring, and the like.
[0015]
As the sphere, various materials can be used as long as they can be pressed and flattened against poly-p-phenylenediphenyl ether terephthalamide. For example, glass, alumina, zirconia, zircon, steel, titania and the like can be preferably cited. The sphere does not need to be a true sphere, and is not particularly limited as long as it has a spherical surface and can flatten the PPDT fiber between the spherical surfaces. For example, the cross section may be oval. However, it may crack or chip and is preferably a true sphere.
[0016]
As the size of the sphere having such a spherical surface, for example, an average particle diameter of 0.1 mm to 6 mm, preferably 1 mm to 5 mm is appropriate. If the diameter is too large, the device becomes too large, which is not preferable. On the other hand, if the diameter is too small, it is difficult to efficiently flatten and separation from the fibers becomes difficult.
The filling rate of the sphere (the volume of the sphere per unit volume) is, for example, 20 to 90%, preferably about 40 to 80% of the closest packing amount.
[0017]
Referring to FIG. 1, a state where PPDT fibers are sandwiched between two spheres (beads) is shown. The PPDT fiber is partially flattened (fiber a) by the pressing force (F) between the spherical surfaces at this time. Then, the flattening is performed over the entire PPDT fiber by continuously performing the partial flattening according to the density of the sphere, the processing time, and the like (fiber b).
[0018]
Specifically, the flattening treatment can be performed by, for example, a sand mill.
The sand mill is composed of a fixed container, a stirrer mounted in the container, and a medium filled in the container, for example, a sphere (bead). In the container, the medium is stirred by the stirrer. It is a mechanism. There are various types of sand mills, for example, a vertical type and a horizontal type, both of which can be used.
[0019]
Specific examples include devices such as sand grinders, dyno mills, and ultra visco mills.
As the media used for the sand mill, glass beads, alumina beads, zirconia beads, zircon beads, steel beads, titania beads and the like can be used, and the average particle diameter is from about 0.1 mm to about 6 mm. Larger particle sizes can be used.
[0020]
The amount of the medium filled in the sand mill container is 20 to 90%, preferably 40 to 80% of the closest packing amount. If the filling rate is too low, a so-called short pass is easily caused in which the fibers come out of the container without being sufficiently flattened. On the other hand, when the filling rate is high, the processing efficiency is good, but in the case of the continuous type, there is a problem that it becomes difficult for the fibers to pass.
[0021]
For example, when the PPDT fiber is flattened with a sand mill, it is appropriate to carry out the slurry in which the PPDT fiber is dispersed in a medium.
As a medium, water is usually the most suitable because of its ease of handling and versatility, but for special purposes such as applications that dislike water, methanol, ethanol and other organic solvents, and these organic solvents and water. Mixed media may be used. Further, a dispersant or the like may be added to the dispersion to improve the dispersibility of the fibers. Hereinafter, examples of the water suspension will be described.
[0022]
It is appropriate to adjust the solid content concentration of the aqueous fiber suspension in the range of usually 0.01 to 2.0% by mass. If it is less than 0.01% by mass, the processing efficiency tends to be poor, and if it is processed at a concentration exceeding 2.0% by mass, it becomes difficult for the fibers to pass and problems such as the fibers becoming entangled easily. Considering the processing efficiency, it is desirable to adjust the solid content concentration in the range of 0.05 to 1.0 mass%.
The sand mill treatment may be a batch type or a continuous type. However, the continuous type is preferable if production efficiency is important. In the case of the continuous type, the residence time (processing time) can be changed by changing the feed flow rate. It is also possible to connect several devices in series for processing.
[0023]
Flatness (the major axis in the fiber orthogonal cross section divided by the minor axis) by appropriately selecting the processing conditions such as material type, average particle size, filling rate, rotational speed of sand mill, processing concentration and processing time ) And the flattening rate (the ratio of the flattened portion in the fiber length direction) can be adjusted.
When a non-woven fabric is produced using the flat PPDT fibers obtained in this manner, the flat surfaces of the fibers are oriented in the horizontal direction, so that the fibers are in contact with each other, and the fibers are in contact with each other compared to the circular cross-section fibers that are point contacts. This increases the contact area and improves the strength of the nonwoven fabric. In particular, in partially flat fibers with a flattening rate of the fiber of less than 1, the partially flattened wide portions are scattered in the length direction of the fibers. Great effect.
[0024]
A nonwoven fabric is produced using the flat PPDT fibers thus obtained. As a method for forming the nonwoven fabric, either a wet method or a dry method may be used, but a wet method capable of obtaining a better texture is preferable. Moreover, you may mix | blend an untreated fiber in the range which does not impair the effect of this invention, and a pulp, a fibrid, etc. can be used as an auxiliary fiber.
In order to adhere flat PPDT fibers to the sheeted nonwoven fabric, it is necessary to blend a binder component. Examples of the binder component include a resin binder and a fibrous binder. In the present invention, a resin binder, particularly a thermosetting resin binder is preferable.
[0025]
The thermosetting resin binder that can be used in the present invention is not particularly limited. For example, epoxy resin, phenol resin, melamine resin, acrylic resin, polyimide resin, polyamideimide resin, silicone resin, and the like can be used. Species or two or more species are appropriately selected and used. In particular, when considering heat resistance, mechanical strength, electrical characteristics, etc., an epoxy resin or a polyimide resin is preferable.
[0026]
The method for imparting a binder to the nonwoven fabric is not particularly limited, a method of spraying a resin binder liquid on a nonwoven fabric formed by a wet method, a method of immersing the nonwoven fabric in a resin binder solution, a method of coating the nonwoven fabric with a resin binder solution Also, a combination of these methods may be used, and after adding a resin binder, heat drying is performed with hot air, a drum dryer, near infrared rays, far infrared rays, or the like.
The resin binder liquid may be either water-based or solvent-based, but water-based is preferable in consideration of the environment and safety. The addition of the resin binder may be performed on-machine or off-machine.
[0027]
The nonwoven fabric thus obtained is subjected to thermal calendering to adjust the density and improve the surface smoothness, and further cure the thermosetting resin binder to improve the strength of the nonwoven fabric. The heat roll temperature of the heat calender is not particularly limited, but it needs to be not less than the softening temperature of the thermosetting resin binder in the nonwoven fabric before the heat calendering treatment and not more than the decomposition temperature of the thermosetting resin binder. Preferably, the temperature is 50 ° C. or more higher than the softening temperature, and is adjusted as appropriate according to the type of resin binder to be used.
Incidentally, when the treatment is performed at a temperature lower than the softening temperature of the resin binder, since the binder is not softened, the binder film is destroyed under the pressure of the calendar, and the strength of the nonwoven fabric is remarkably lowered. On the other hand, when the temperature is too high, thermal decomposition of the resin binder occurs, causing troubles such as a decrease in strength of the nonwoven fabric and generation of foreign matter.
[0028]
The linear pressure at the time of thermal calendering is not particularly limited, and is appropriately selected according to the target density. However, if the linear pressure is too low, the density profile in the width direction and the surface smoothness deteriorate. The linear pressure is preferably 0.5 kN / cm or more, particularly preferably 1 kN / cm or more. As an upper limit, it will be about 10 kN / cm, for example.
The density of the nonwoven fabric is not particularly limited, and is appropriately determined in consideration of the strength of the nonwoven fabric and the impregnating property of the resin varnish in the subsequent prepreg manufacturing process. Incidentally, when the density is too high, the amount of impregnation is reduced because there are few voids impregnated with the resin varnish. On the other hand, if the density is too low, the varnish sinks into the nonwoven fabric in the drying step after impregnation of the varnish, and the surface attachment decreases. When a laminated board is made using such a prepreg, the copper foil and the non-woven fabric are in direct contact with each other, and the copper foil peel strength of the laminated board is deteriorated and the surface smoothness is deteriorated. Therefore, it is preferable to adjust the density of the non-woven fabric after the thermal calendar treatment to a range of 0.5 to 1.0 g / cm ³ .
[0029]
The nonwoven fabric produced as described above is impregnated with a matrix resin varnish. As the matrix resin, an epoxy resin is generally used, but known resins such as a polyphenylene ether (PPE) resin, a phenol resin, a polyimide resin, a bismaleimide (BT) resin, and a fluorine resin can be widely used. Species or two or more species are appropriately selected and used. Of course, a flame retardant, a curing catalyst, a filler or the like may be blended in the resin varnish depending on the purpose.
The nonwoven fabric impregnated with the varnish is heated and cured under a condition of about 130 to 160 ° C., for example, to be a B stage (semi-cured state) to obtain a prepreg. The prepreg is appropriately combined with a copper foil and laminated, and for example, thermoformed while being pressed at about 150 to 250 ° C. to obtain a laminated board. In particular, since the prepreg of the present invention can be thinned, it is suitable for a build-up layer of a build-up substrate.
[0030]
【Example】
EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention further in detail, the scope of the present invention is not limited at all by these Examples and comparative examples.
In Examples and Comparative Examples, “%” means “% by mass” unless otherwise specified.
[0031]
Example 1
A PPDT fiber (trade name: Technora, fiber diameter 1.5d, fiber length 3.0 mm) having a circular cross section shown in FIG. 2 was dispersed in water to prepare a slurry having a solid content concentration of 0.3%. Next, a horizontal sand mill having a capacity of 1400 ml filled with alumina beads having an average particle diameter of 3 mm so as to have a filling rate of 20% (relative to the closest packing amount) (manufactured by Shinmaru Enterprises, trade name: DYNO-MILL TYPE KDL) -PILOT), the slurry was fed at a flow rate of 350 ml / minute (residence time 2.6 minutes) and processed at a rotational speed of 2400 rpm (circumferential speed 12.6 m / second). The treatment temperature was adjusted to 30 ° C. by adjusting the temperature of the circulating water for cooling. The treated fiber is shown in FIG. The treated fibers were partially flattened partially.
[0032]
This fiber was formed into a sheet by a wet method so that the rice paper weight after drying was 16 g / m ² with a square hand-making machine. A thermosetting epoxy resin emulsion was added to this sheet by a spray method so that the content in the nonwoven fabric after drying was 20%, and dried by heating to obtain a nonwoven fabric having a rice basis weight of 20 g / m ² .
Subsequently, it processed so that it might become a density of 0.6 g / cm < ³ > with the heat | fever calendar with a roll temperature of 200 degreeC, and the nonwoven fabric was obtained.
[0033]
Example 2
The sand mill treatment was performed in the same manner as in Example 1 except that the packing rate of alumina beads in Example 1 was set to 70%. The treated fiber is shown in FIG. The treated fibers were all flattened along the length direction of the fibers.
Using this fiber, a nonwoven fabric was obtained in the same manner as in Example 1.
[0034]
Comparative Example 1
Example except that poly-p-phenylene terephthalamide fiber (manufactured by Toray DuPont, trade name: Kevlar, fiber diameter 1.5d, fiber length 3.0 mm) was used instead of the PPDT fiber in Example 2. Although the sand mill treatment was performed in the same manner as in No. 1, fibers were clogged during the sand mill treatment, and continuous treatment could not be performed. The treated fiber taken out from the container was fibrillated and was not flat.
[0035]
Comparative Example 2
A nonwoven fabric was obtained in the same manner as in Example 1 except that the sand mill treatment in Example 1 was not performed.
[0036]
Comparative Example 3
Nonwoven fabric in the same manner as in Comparative Example 2, except that the basis weight after drying of the nonwoven fabric after hand-drawing in Comparative Example 2 was 14 g / m ² , and the binder content of the nonwoven fabric after adding and drying the binder was 30%. Got.
[0037]
<Solvent resistance of nonwoven fabric>
Cut the non-woven fabric into a width of 30 mm and a length of 150 mm so that the paper passing direction of the calendar is the length direction, and after immersion in acetone for 5 minutes, perform a tensile test under conditions of a span of 100 mm and a pulling speed of 10 mm / min. Peak intensity (kN / m) was measured. The measurement was performed 5 points at a time and the average value was calculated.
[0038]
<Nonwoven fabric texture>
The texture of the nonwoven fabric was evaluated by visual evaluation using transmitted light and evaluated according to the following criteria.
○: There is little unevenness in the density of the sheet, and there are few pinholes.
Δ: Although there are uneven density and / or pinholes in the sheet, there is no practical problem.
X: Sheet unevenness and / or pinholes are large and unsuitable.
[0039]
The evaluation results of the nonwoven fabrics of Examples and Comparative Examples are shown in Table 1 below. As is apparent from Table 1, it is possible to obtain flat PPDT fibers by the production method of the present invention, and the nonwoven fabric made of this flat PPDT fiber has higher strength than the nonwoven fabric made of the normal circular cross-section PPDT fiber. It has excellent texture and few pinholes.
[0040]
[Table 1]

Fiber A: PPDT fiber (manufactured by Teijin, trade name: Technora, fiber diameter 1.5d, fiber length 3.0 mm)
Fiber B: Poly-p-phenylene terephthalamide fiber (manufactured by Toray DuPont, trade name: Kevlar, fiber diameter 1.5d, fiber length 3.0 mm)
[0041]
【The invention's effect】
By the production method of the present invention, flat PPDT fibers can be produced simply, efficiently, and inexpensively. This flat PPDT fiber has good tensile strength and texture when made into a nonwoven fabric compared to a para-aramid fiber having a normal circular cross section, and has few pinholes, making it ideal for obtaining a thin nonwoven fabric for laminates. Fiber.
[Brief description of the drawings]
FIG. 1 is a diagram showing a flattening mechanism.
FIG. 2 is a photomicrograph of PPDT fiber before flattening treatment.
3 is a photomicrograph of partially flattened PPDT fiber prepared in Example 1. FIG.
4 is a photomicrograph of the totally flattened PPDT fiber prepared in Example 2. FIG.

Claims (2)

A method for producing a poly-p-phenylene diphenyl ether terephthalamide fiber in which part or all of the fiber is flattened, wherein the flattening presses the poly-p-phenylene diphenyl ether terephthalamide fiber between spherical surfaces. A method characterized by being performed. The method according to claim 1, wherein the flattening is performed in a sand mill.

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