JP3179285B2 - Aramid non-woven fabric - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a cushioning material used in a pressing process of an electrical insulating material or a manufacturing process of a printed circuit board, in which the surface portion is free from minute damage and the appearance quality is particularly important. that it can be utilized to the spacer material
The present invention relates to an aramid nonwoven fabric.

[0002]

2. Description of the Related Art With the recent refinement of electric and electronic equipment and the rapid development of technology, the required quality of electrical insulating materials and printed circuit board materials used in these equipment is becoming increasingly precise and strict. Therefore, slight surface damage and adhesion of foreign matter are not allowed, and in addition, a high degree of surface smoothness is required. In addition, in the process of forming the electric insulating material and the process of manufacturing the printed circuit board, a nonwoven fabric made of aramid fiber having a relatively low heat shrinkage rate, heat resistance, flexibility and thin-leaf properties, and also having cushioning properties is required.

[0003] In response to such a request, Japanese Patent Publication No. Sho 6
Japanese Patent Application Laid-Open No. 1-30064 describes an aramid felt and a method for producing the same. The nonwoven fabric produced by this method has high heat resistance, high cushioning properties, etc. Since the fiber in the shape of a letter is easy to come off from the surface and the surface is poor in smoothness, a fine uneven pattern is transferred to the surface of the product on the other side. JP-A-4-6708 discloses a thin paper obtained by heating and pressurizing a wet paper formed from an aqueous slurry comprising a mixture of aramid short fibers and aramid pulp by a wet papermaking method. However, electrical insulation paper made from thin paper has high heat resistance, flexibility, and thinness,
Since the short fiber length is short, the fluff is easy to come off, and since pulp is used, the bulk density is high, the cushioning property is inferior, and the heat shrinkage rate is high, so that not only the required properties in the manufacturing process can not be satisfied, but also manufacturing There is a problem that the cost increases. Japanese Patent Application Laid-Open No. 6-342609 describes a method for producing a nonwoven fabric obtained by heating an aramid nonwoven fabric with a hard roll.
An electric insulating material of 5 μm or less and a high-grade printed circuit board do not have fuzzy foreign matter attached thereto, but generate harmful wrinkles on the board shape because of flexibility and a small swelling rate in a thickness direction at a high temperature. In order to solve these problems, it is necessary to be more flexible than before in order to improve the adhesiveness at the contact surface with the resin layer and the handling during production. In addition, in order to prevent the occurrence of wrinkles and the like, which are important drawbacks of printed boards, it is desired to improve the thermal dimensional stability or the printed board supporting properties during heat treatment.

[0004]

DISCLOSURE OF THE INVENTION The present inventors have conducted intensive studies to solve the above problems, and as a result, when aramid fiber nonwoven fabric having a low basis weight is preliminarily heat-treated and shrunk, and then heated and pressed, the surface smoothness required by the market is obtained. The present inventors have found that thin paper having low fuzziness and low heat shrinkage can be obtained, and the present invention has been completed. That is, the object of the present invention is flexibility,
An object of the present invention is to provide an aramid nonwoven fabric having improved thermal dimensional stability and a swelling ratio in a thickness direction during heat treatment, and a method for producing the same.

[0005]

That is, the present invention provides "(Claim 1) substantially
Composed of polymetaphenylene isophthalamide fiber
After pre-heat treatment at 280-350 ° C, pressurization temperature 230-
An aramid nonwoven fabric which is hot- pressed at 350 ° C. and a linear pressure of 150 to 250 kg / cm, and has a basis weight of 2
0 to 50 g / m ² , bulk density 0.25 to 0.45 g / c
m ³ , flexibility is 10 to 60 mm by cantilever method, 35
The heat shrinkage after heat treatment at 0 ° C. for 10 minutes is 1.0 to 6.
An aramid nonwoven fabric characterized by having a swelling ratio in the thickness direction of 60% to 150% after heat treatment at 0% and 350 ° C. for 10 minutes, and the number of lint coming out from one or both sides is 10/10 cm ² or less. ".

Here, aramid is polymetaphenylene.
It is sophthalamide .

When used as short fibers (staples)
Fiber length of the poly meta-phenylene isophthalamide fibers, about 25～80Mm, preferably about 35～65Mm. Other fibers as needed, for example, polyparaphenylene La reflex isophthalamide-based, etc. may be mixed with an appropriate amount. The single fiber fineness of the fiber is 10.0 denier or less, more preferably 0.5 denier.
~ 4.5 denier. The method for producing the nonwoven fabric is not particularly limited. It can be obtained by entanglement of a web obtained by a conventionally known method, for example, the following method or the like by high-pressure high-speed fluid injection such as needling or a water jet, or by integrating it with an adhesive or hot-press processing. (A) A method in which a crimped short fiber (staple) and a carding machine such as a flat card or a roller card are opened to form a sheet. (B) A method of stretching and opening a laminate of long fiber tow in the width direction. (C) A method in which long fibers are randomly laminated on a belt. (D) A method in which short fibers are randomly laminated on a belt while being opened with a high-speed fluid.

The basis weight of the nonwoven fabric used in the present invention is 20 to 50.
A range of g / m ² is preferred. More preferably, 15 to 3
Within the range of 5 g / m ² . If the basis weight exceeds 50 g / m ² , it will be too thick and heavy to meet the market requirements. When the grammage is less than 20 g / m ² , the strength and cushioning properties required for practical use are insufficient.

The bulk density is between 0.25 and 0.45 g / cm ³ . If the bulk density is less than 0.25 g / cm ³ ,
Swelling in the thickness direction after heat treatment for 10 minutes at less than 60%. When the bulk density exceeds 0.45 g / cm ^3, practically necessary cushions resistance is insufficient.

The flexibility by the cantilever method is 10 to 60.
mm. If the flexibility by the cantilever method is less than 10 mm, the workability in the manufacturing process is deteriorated due to the excessive flexibility. If the flexibility by the cantilever method exceeds 60 mm, wrinkles are likely to be formed in the product during the manufacturing process.

The heat shrinkage after heat treatment at 350 ° C. for 10 minutes is 1.0 to 6.0%. If the heat shrinkage is less than 1.0%, production becomes difficult. If the heat shrinkage exceeds 6.0%, wrinkles will occur on the printed circuit board when it is combined with a copper foil.

The swelling in the thickness direction after heat treatment at 350 ° C. for 10 minutes is 60 to 150%. If the swelling in the thickness direction is less than 60%, a gap is generated between the layers of the laminated printed board when it is combined with the copper foil, so that the thickness of the resin layer becomes uneven. If the swelling in the thickness direction exceeds 150%, the fibers are transferred to the resin layer in a pattern and hinder uniformity of the laminated printed circuit board.

The heating and pressurizing may be performed by a calender roll or a flat plate press. Usually, calendering with good production efficiency is preferred. In the case of calendering, between two hard surface rolls having a diameter of about 25 to 100 cm, or between one hard surface roll having a diameter of about 15 to 80 cm and an elastic roll having a diameter of about 30 to 100 cm The heating and pressurizing are performed. The upper roll is preferably a hard roll having a linear embossed pattern on the roll surface, and the lower roll is preferably an elastic roll in order to improve flexibility and lint-removing property. Processing is possible by this.

In order to reduce the fluff removal property, the distance between the lines of the embossed pattern is desirably set to 1/200 to 1/400 of the fiber length in consideration of the improvement of the surface smoothness. In particular, in order to improve the swelling property in the thickness direction at a high temperature, it is desirable that the difference between the peaks and valleys of the emboss is 20 to 40 μm and the bulk density is 0.25 to 0.45 g / cm ³ . The preheating temperature is 280-350 ° C and the pressurizing temperature is
The temperature, i.e., the calendar temperature, is from 230 to 350C, more preferably from 270 to 330C. The pressing force is 150
２５０250 kg / cm. When the heating temperature and the pressing force are out of the above ranges, the bulk density of the obtained nonwoven fabric is 0.25 to 0.25.
0.45 g / cm ³ , and not only the cushioning property is reduced, but also other properties cannot be satisfied. That is, if the heating temperature is too low, the fluff removal property also decreases. Conversely, if the heating temperature is too high, the flexibility and cushioning properties are lost and the purpose cannot be achieved. On the other hand, if the pressing force is too low, the surface smoothness and the fluff removal property deteriorate, and if the pressing force is too high, on the other hand, the bulk density deviates from the target value and the cushioning property deteriorates.

[0015]

As described above, the aramid nonwoven fabric of the present invention is excellent in heat resistance, flexibility and thin-leaf properties, and has excellent cushioning properties and fluff removal properties. Since it has insulating properties, it is useful not only in the process of forming an electrical insulating material and the process of manufacturing a printed circuit board material, but also very useful as a heat-resistant insulating spacer for various electric and electronic devices.

Hereinafter, the present invention will be described more specifically with reference to examples. The various characteristic values shown in the examples are values measured by the following methods. <Basic weight> It was measured according to JIS-P-8124. <Thickness> The thickness was measured according to JIS-C-2111. <Bulk density> Measured according to JIS-C-2111. <Heat Shrinkage> A sample of 30 cm in length and 30 cm in width was collected from a portion excluding both ends of the nonwoven fabric.
After drawing a square having a size of 5 cm and a width of 25 cm, the sample was placed in a drier (manufactured by Tabai Espec Corp.) and dried.
The heat shrinkage in the vertical and horizontal directions after heat treatment at 10 ° C. for 10 minutes was calculated by the following equation. Heat shrinkage _{(%) = {(S 0} -S) / S 0} × 100 S 0: dimension before heat treatment of the square drawn in the sample S: Dimensions after square heat treatment drawn in the sample

The heat shrinkage is calculated for each of the vertical direction and the horizontal direction, and then the average value of the heat shrinkage in the vertical direction and the horizontal direction is obtained. This value is used as the heat shrinkage of the sample. <Fuzz removal property (number of fuzz removal)> Adhesive tape prepared according to JIS-Z-1522 is adhered to the surface of aramid nonwoven fabric, pressurized at a linear pressure of 1 kg / cm, then peeled off the adhesive tape and adhered. The number of fluff adhering to the tape side was counted (book / 10 cm ² ). <Measurement of swelling ratio in thickness direction> The sample size was 10 cm in length and 10 cm in width, and 350 ° C. in a state where a load of 10 g / cm ² was applied in the thickness direction.
The thickness change rate after heat treatment for 20 minutes was determined. <Measurement of flexibility (45 ° cantilever method)> According to JIS-L-1079.

[0018]

Example 1 Single yarn fineness 2.00 denier, fiber length 51 m
m of polymetaphenylene isophthalamide short fiber,
The fibers were opened with a carding machine so that the fibers were arranged in the direction of travel of the web as much as possible, to produce a web of about 30.2 g / m ² . Subsequently, the web was subjected to slight needling and entangled to obtain a nonwoven fabric of about 30.5 g / m ² . This was previously subjected to hot air drying at 320 ° C. for 5 minutes, and then this nonwoven fabric was calendered between a linear embossing roll having a diameter of 15 mm and an elastic roll under the conditions shown in Table 1 to obtain a thin-leafed aramid nonwoven fabric. Was. Various characteristics of this nonwoven fabric were measured. The results are shown in Tables 1 and 2.

[0019]

Example 2 The polymetaphenylene isophthalamide short fibers used in Example 1 were opened by a carding machine in the same manner as in Example 1 so that the fibers were arranged in the direction of travel of the web as much as possible.
A low basis weight web was made. Subsequently, the web was entangled with a high-pressure, high-speed water jet and then dried to obtain a nonwoven fabric of about 30.0 g / m ² . This is 2
The nonwoven fabric was heat-treated at 80 ° C. for 5 minutes, and then the nonwoven fabric was calendered under the conditions shown in Table 1 between a linear embossing roll having a diameter of about 15 mm and an elastic roll in the same manner as in Example 1. A non-woven fabric was obtained. Various characteristics of this nonwoven fabric were measured. The results are shown in Tables 1 and 2.

[0020]

Example 3 A thin leaf-like aramid nonwoven fabric was obtained in the same manner as in Example 2 except that the calendering conditions were the same as those shown in Example 3 in Table 1, and various properties of the nonwoven fabric were measured. Are shown in Tables 1 and 2. In addition, the bulk density of the obtained nonwoven fabric was 0.1% because of the high pressure during calendering.
It was 43 g / cm ³ .

[0021]

Comparative Example 1 Approximately 30.2 g same as that used in Example 1
/ M ² , a thin-leafed aramid nonwoven fabric was obtained in the same manner as in Example 1 except that the nonwoven fabric was calendered under the processing conditions shown in Comparative Example 1 in Table 3. Various properties of this nonwoven fabric were measured, and the results are shown in Tables 3 and 4. The basis weight of the obtained nonwoven fabric was very low because the treatment temperature at the time of calendering was considerably low.

[0022]

Comparative Example 2 About 30.0 g same as that used in Example 2
/ M ² , a thin leaf aramid nonwoven fabric was obtained in the same manner as in Example 2 except that the nonwoven fabric was calendered under the processing conditions shown in Comparative Example 2 in Table 3. Various properties of this nonwoven fabric were measured, and the results are shown in Tables 3 and 4. The basis weight of the obtained nonwoven fabric had a large heat shrinkage of 8.5% because the heat treatment temperature was considerably low.

[0023]

Comparative Example 3 About 30.0 g same as that used in Example 2
/ M ² , a thin-leafed aramid nonwoven fabric was obtained in the same manner as in Example 2 except that the nonwoven fabric was calendered under the processing conditions shown in Comparative Example 3 in Table 3. Various properties of this nonwoven fabric were measured, and the results are shown in Tables 3 and 4. The basis weight of the obtained nonwoven fabric was significantly shrinkage due to a considerably high treatment temperature, and was 40.8 g / m ² .

[0024]

Comparative Example 4 Approx. 30.0 g same as that used in Example 2
/ M ² , a thin-leafed aramid nonwoven fabric was obtained in the same manner as in Example 2, except that the nonwoven fabric was calendered under the processing conditions shown in Comparative Example 4 in Table 3. Various properties of this nonwoven fabric were measured, and the results are shown in Tables 3 and 4. The swelling ratio of the obtained nonwoven fabric in the thickness direction is such that the bulk density is 0.22 g / c.
It was 30% for low and m ^3.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

[0028]

[Table 4]

Continuation of the front page (72) Inventor Takeo Kimura 1-6-7 Minamihonmachi, Chuo-ku, Osaka-shi, Osaka Teijin Limited (56) References JP-A-61-167070 (JP, A) (58) Survey Field (Int.Cl. ⁷ , DB name) D04H 1/00-18/00

Claims (2)

(57) [Claims] 1. The method of claim 1 , wherein the polymethaphenylene isophthala is substantially polymethaphenylene isophthala.
Made of mid fiber, pre-heated at 280-350 ° C
After that, pressurization temperature 230-350 ° C, linear pressure 150-250k
Aramid non-woven fabric that is hot- pressed at g / cm
The nonwoven fabric has a basis weight of 20 to 50 g / m ² , a bulk density of 0.25 to 0.45 g / cm ³ , a flexibility of 10 to 60 mm by a cantilever method, and heat shrinkage after heat treatment at 350 ° C. for 10 minutes. The rate of swelling in the thickness direction after heat treatment at 350 ° C. for 10 minutes is 60 to 150%, and the number of lint from one or both sides is 10/10 cm.
Aramid nonwoven fabric characterized by being ² or less. 2. A method according to claim 1 aramid nonwoven fabric is a spun lace allowed entangled with a water jet of pressurized high velocity flow
The aramid nonwoven fabric according to the above.