JPS5844470B2 - Mousaikanshiyo Melt Blow - Yodai - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a die for melt blowing thermoplastic resins that uses a capillary tube in the die opening.

More particularly, the present invention relates to a die having a constant internal diameter and a single row of die openings that connect to a plurality of capillary tubes and are precisely aligned as required for a meltblowing process.

Melt tubes and suitable dies are disclosed in the following publications and patents: US Pat.

1. Naval Research Laboratory Report (
Naval Research Laboratory
Report ) 4364, ``Manufacture of fine organic fibers (Manufacture of fine organic fibers)
Organic Fibers) J+4, 1954
May 15th 2, Wente, Va.
nA, ), Industrial and Engineering Chemistry
gineering Chemistry) t
48+ No. 8 (1956, PP, 1342-13
46).

3. Naval Research Laboratory Report (
Naval Rcsearch Laboratory
Report) 5265, “An Improved Dev
ice for the formation of 5
upperfine, thermoplasticF
ibers) J, February 11, 1959.

4. British Patent No. 1,055,1875. U.S. Patent No. 3,379,8116, Japanese Patent Publication No. 25871 of 1960, 1961
Published: October 30th In accordance with the present invention, a melt blowing die having a generally triangular cross section, a die block having a chamber for containing a thermoplastic material, and an inner diameter of 254 microns (0,010 inches) to 635 microns (0,010 inches). , 025 inches), outer diameters of 635 microns (0,025 inches) to 1.270 microns (0,050 inches), and having a smooth inner surface and a uniform diameter; the other end being held firmly within said die block and each in substantially planar contact with each other, said other end containing a capillary tube disposed in precise alignment to eliminate sharp edges; The one end of the capillary is fluidly connected to the chamber, and the other end of the capillary has a pointed end whose cross section is set within a range of 300 to 900 mm and is formed to be fluidly connected to the outside of the Gui block; Further, an upper gas injection passage and a lower gas injection passage are provided, which are defined by a gas plate, and the pointed end of the gas plate is spaced parallel to and close to the pointed end of the capillary tube. This provides a melt blowing die in which the gas plate is provided at the same angle as the pointed end.

The die is a three-piece assembly and the capillary tube is contained in a bonding layer between the three pieces forming the die assembly.

During the research that led to the present invention, it was discovered that the dies used in the melt blowing process require very tight tolerances.

This makes their manufacture very difficult and expensive.

One of the reasons for the high cost is that many very small holes have to be drilled.

A second source of manufacturing difficulty is that all the holes must open onto a sharp blade and the rows of holes must line up precisely over long distances.

A method has been found for making a type of die which overcomes some of the above difficulties and reduces the cost of the die.

In this method, instead of using holes drilled in the die (
This capillary tube is used.

problems associated with precise drilling by using capillary tubes;
That is, electrical discharge machining of very small holes is avoided.

More importantly, it is possible to line up the capillary tubes accurately, so the holes line up exactly in a straight line.

Generally, the die manufacturing method used when using a capillary tube is as follows.

Machining the desired melt cavities in the metal blocks that together form each half of the die.

The melt cavity distributes a flow of thermoplastic liquid to the mouth of the hole.

Then cut a slot precisely where the capillary tube will be attached.

Each block will have identical slots with a depth equal to or slightly less than the radius of the capillary tube.

Each block is then provided with a channel along the slot (outside the location of the hole) and at the center of the tube.

These channels are filled with hangs and the solder is smoothly scraped off with a machine.

A capillary tube is packed into one elongated hole, and the two block pieces are brought together and carefully aligned.

The pair of blanking strips are then tightened to complete the solder joint.

The bonded dies are placed in a nitrogen furnace and then run through this machine.

Other methods of binding may also be used.

The advantages of using a capillary die are as follows.

■The holes are not drilled, so they can be made longer.

2. The hole diameter is extremely uniform.

3. There are no barrier burrs inside the hole.

4. Meltblowing (it is easier to obtain the precise alignment needed to make a superior web).

5. - Compared to a block consisting only of pieces, it is easier because the processing of the melt only takes place on separate book pieces.

6. Production costs are greatly reduced.

Made using a 5 cm (2 inch) die or capillary method.

This die worked satisfactorily in the melt blowing process.

Therefore, as melt blowing and dies are generally described in the above literature, this specification details the new die apparatus of the present invention.

Details of this point can be better understood by referring to the drawings.

Referring to Figure 1, the melt blowing process begins with the hopper 1.
This is done by placing pellets of one or more thermoplastics in the container.

Thermoplastics are thus resins, which together with thermoplastics may contain dyes, additives or modifiers.

These are conveyed to extruder 2. For thermoplastic resins of the following types, it is possible to thermally treat the resin before introducing it into the extruder 2, or by thermally treating the resin in the extruder 2 and the die section 3 or between them. It is necessary to reduce the viscosity.

For example, if polypropylene is melt blown, the polypropylene is placed in hopper 1 and extruder 2.
at temperatures above 288°C (550'F), preferably in the range of 327-427°C (620-800'F).

The degree of heat treatment required will vary depending on the molecular weight of the polypropylene.

Separate patent applications have been filed for significant improvements in specific techniques for controlling degradation.

The resin is conveyed through the extruder 2 to the die head 3 by a drive 4 which rotates an extruder screw (not shown).

The die head 3 is usually equipped with a heating plate 5 used for heat treatment of the thermoplastic resin before melt blowing.

Liquid resin is pumped out from an array of capillary tubes 6 that are tightly fitted into the die bed 3.

There, the liquid resin is exposed to a gas stream and attenuated into continuous fibers 7 which are collected in a moving collection device 8, such as a drum 9, to form continuous pines 1-10.

A stream of hot gas, preferably air, which attenuates the thermoplastic, is supplied to the gas jets, i.e. to adjacent edges 11, 12 on both sides (above and below) of the die opening.

Hot gas is supplied to the grooves 11 and 12 from gas pipes 13 and 14, respectively.

Now, referring to FIG. 2, the thermoplastic resin passing through the inlet 1γ is -L die block 15 and lower die block 1.
This is introduced behind the die head 3 consisting of 6.

The resin is conveyed to chamber 18 between -L and lower gui blocks 15 and 16.

According to the invention, the upper and lower diflocks 15 and 16
A cut edge is cut in the opposite direction of the chamber 18 to form recesses 19 and 20 and provide a cavity for attaching the capillary tube 6.

The capillary tube is tightly positioned with the solder 21 in the recesses 19 and 20 between the die blocks 15 and 16.

In this embodiment, the capillary tube 6 ends at a sharply angled point, indicated at A, outside the chamber 18.

The die tips 22 are generally triangular in cross section and are provided by machining the outer surfaces of the dive jigs 15 and 16, as will be described in detail later.

The tip A of the capillary tube 6 is created by mechanical manipulation.

The angle of the tip is in the range of 300° to 900°, preferably 55° to 65°, and particularly preferably 60°.

An upper gas cover plate 23 and a lower gas cover plate 24 are connected to the upper and lower dive rings 15 and 16.

Hot gas is supplied through an inlet 25 in the gas plate 23 and an inlet 26 in the gas plate 24.

Place a suitable baffle plate (not shown) in the upper gas chamber 27.
and the lower gas chamber 28, thereby making it possible to flow a constant flow rate of gas through the grooves 11 and 12.

FIG. 3 shows the relationship of the capillary tubes 6 to each other after they have been aligned and bonded into the preferred arrangement.

Referring generally to FIGS. 4 through 10, these figures illustrate techniques for making the die of the present invention.

A recess 19 is machined into the Goo block 15 and an identical recess 20 is machined into the Goo block 16.

The dimensions of the recesses 19 and 20 are determined in relation to the outer diameter of the capillary tubes 6 so as to hold exactly the desired number of capillary tubes 6 in the operating position.

The recesses 19 and 20 are the upper and lower Gui blocks 15 and 1.
6, it extends near the shoulder 29 of the upper Goui block 15 and near the shoulder 30 of the lower Goui block 16.

Desirably, the height of shoulders 29 and 30 does not exceed the outer diameter of capillary tube 6.

FIG. 4 illustrates the relationship of the various parts prior to final assembly and actual solder bonding.

Solder pools 31 and 32 are shown in cross section.

The solder reservoir 31 is located in the upper die block 15 and the solder reservoir 32 is located in the lower die block 16.

In the lower die block 16 of FIG. 5, the solder reservoir 32 consists of two U-shaped parts on both sides of the recess 20, and there is one groove 32a beyond the lower part of the recess 20.

Solder reservoirs 31 and grooves 31a are cut out in the upper die block 15 in the same arrangement.

During assembly, solder reservoirs 31 and 32 are filled with solder 21.

After the solder has hardened, it is flattened by a machine so that it does not protrude from the solder pool.

The desired number of capillaries is then placed in the recess 20 of the lower die block 16.

The upper die block 15 and the lower die block 16 are bolted together.

As shown in Figure 7 (these two block pieces are attached to the bolt 3
3 (clamped together), whereby the capillary tube 6 is firmly held within the four parts 19 and 20, and the internal ends of the capillary tube 6 are secured to the shoulders 29 and 30 of the upper die block 15 and the lower die block 16 ( This is touching.

The guide blocks 15 and 16 are usually provided with a chamber 18 which is necessary for guiding the thermoplastic resin into the capillary tube 6 by mechanical operation.

In order to heat the solder 21 and to hold the capillary tube 6 tightly, an isolating pad 34 (shown in FIG. 1) is placed in the chamber 18 before additional solder 21 is introduced. Because it is packed, solder 21 does not flow into chamber 18 while the solder is being heated for bonding.

In FIGS. 8 and 9, an external solder pool 35 is attached to the die blocks 15 and 16, and it is connected to the screws 36 and 3γ.
It is bolted on.

The solder reservoir 35 acts as a pressure head for refilling with solder.

After the die blocks 15 and 16 are firmly tightened with the bolts 33, the capillary tube 6 is firmly fitted into the recesses 19 and 20, and one end of the capillary tube is in contact with the shoulder portions 29 and 30, the goo head 3 heats the solder 21. To be put into a furnace in order to

When the die head 3 is placed in the furnace, as shown in FIG. The space between the capillaries 6 is filled.

When the die head 3 is cooled, the capillary tube 6 becomes the Gui block 15.
and 16.

The position of the guiflocks 15 and 16 while in the furnace, i.e. while being heated, is at the position f as shown in FIG.
It is desirable that this is the case.

The isolation stuffing 34 has the solder 21 connected to the capillary tube 6 or the chamber 1.
8.

The heating must be done so that the solder 21 completely fills the space around the capillary tube 6 and becomes a complete barrier in the recesses 19 and 20, preventing the thermoplastic resin from flowing in. .

Before the capillary tube 6 is machined, one end of each tube is attached to the Diflock 15.
and 16 ends.

In the final mechanical operation, the goo locks 15 and 16 are provided with a goo tip 22 having a triangular cross section.

It terminates in a tip A which is angled in cross section.

FIG. 10 (The angle α shown here is between 30° and 900°, preferably between 55° and 65°, and preferably about 600°.

In one embodiment, when the die blocks 15 and 16 and the capillary tube 6 are machined, the tube 6 is placed between the surface 38 of the die block 14 and the surface 3 of the die block 16.
9 has an integral surface, forming an included angle α.

See Figure 10. Further details of the preferred embodiments are provided below.

Fig. 6 (The recess 20 is located inside the lower kadai block 16 (approximately 6.35 to 25.4 mm (approximately 74 to 1 inch)
, more preferably about 12.7 mm (about 1/2 inch)
, extending (indicated by dimension X).

The capillary tube 6 has an inner diameter of about 254 to 635 microns (0.01
0 to 0.025 inch), and the outer diameter is 635 to 1
270 microns (0.025 to 0.050 inch total), 762 to 1016 microns (0.03 to 0.04 inch)
inch) is preferred.

In one embodiment of the present invention, the capillary tube 6 used is a seamless tube of #316 stainless steel.

This type of steel can withstand the temperatures used during the joining operation.

This tube has an inner diameter of 381±127 microns (0,015±0
．． 0,005 inch), outer diameter 787 microns (0,031 inch)
inch) and length 254 (1,0 inch).

Although a capillary tube is shown with a circular cross section, the cross section may be square, rectangular, or other shapes.

It is understood that the outer diameter of the capillary tube controls the spacing of the gou openings.

This distance (762 to 1016 microns (3 to 1 center)
A range of 0 to 40 mils is preferred.

The dimensions of the shoulder 30 of the lower guiflock 16 and the depth of the recess 20 will vary depending on the size and shape of the capillary tube 6 used.

Typically, the dimensions are such that when the guiflocks 15 and 16 are in the operating position, they hold one capillary tube snugly in the quadrants 19 and 20.

From this, it follows that if the dimensions of the recesses 19 and 20 are the same, the depth Z is half the outer diameter of the capillary tube used, and the height Y of the shoulder is equal to or less than the rod of the wall of the capillary tube used. be.

Suitable solders when using No. 316 stainless steel capillary tubes are Al951%, Cu22%, Zn19%,
Eutectic alloy 1801 with 7% Cd and 1% Sn
It is a silver hanger.

The solvent used for such solders is eutectic alloy 1801.
-B solvent.

This special solder is manufactured by the manufacturer (according to the manufacturer) 5930C (11
It melts at 613°C (1135'?).

If other soldering solvents are used, however, if the solder described above is used, the upper hook 15 and the lower hook 16 must be placed in the oven or soldered with a different solder. ), the bonding temperature of the solder used is increased, and the temperature above (this is heated).

Therefore, when eutectic alloy 1801 solder is used, at least 6]-3°C (1135'l') θM degrees are used.

FIG. 11 shows an embodiment of a die head in which a die block or capillary tube is machined so that the cross section of each tip of the capillary tube has a desired angle (no scraping is required).

In this case, a capillary tube with a conical cross section is used.

Thus, the die \rad 40 is made from the upper die block 42 and the lower die block 43.

A groove or recess 44 is provided in the upper die block 42 to receive the capillary tube 41, and a groove or recess 45 is provided in the lower die block 43.

Gutters 44 and 45 terminate at shoulders 46 and 47.

Capillary tubes 41 abut these shoulders.

In operation, the thermoplastic resin is placed in a chamber 49 connected to the
8 and is introduced to the back side of the goo head 40.

Chamber 49 supplies resin to capillary tube 41 .

In this embodiment, the capillary tube 41 is connected to the die blocks 42 and 4.
3 to the outside by a distance of about 1/2 or less of the length of the tube without any support from the outside other than the die block.

Upper gas cover plate 50 and lower gas cover plate
1.51 is -L force air, that is, gas chamber 52 and lower gas chamber 5
form 3.

The capillary tube 41 has a conical tip A, the angle of which is within the range of 300 to Q00, preferably within the range of 55° to 65°.

The tips 54 and 55 of the single-blade air plate 50 and the lower air plates 1-51, respectively, have an angle similar to that of the tip A of the capillary tube 41.

Furthermore, the tips 54 and 55 of the air plates are approximately 25.4 to 127 microns (25.4 to 127 microns) substantially opposite the cone of the capillary tube 41.
~5 mils).

The die of the present invention has several fabrication and operational advantages over other dies known or being developed for melt blowing dies.

Because dimensional tolerances must be precise in melt-blowing dies, the die of the present invention can be installed over a large width of the melt-blowing die (40-60 inches (1-1.5 m) or more, i.e., 500-2000 capillaries). It is possible to install certain small gouge openings 1 without the high manufacturing costs as in the case of the previously described method.

Furthermore, as discovered during the research process,
must be drawn in a straight line over long distances.

Therefore, according to the manufacturing method of the present invention, a new die device can be obtained through a process consisting only of relatively simple mechanical operations, the tolerances caused by the mechanical operations are extremely small, and moreover, only one melt blowing process is required. The necessary tolerances for use are provided.

Furthermore, the die of the present invention is easily cleaned and allows greater production of melt-bubbled materials.

It is also an advantage of the device of the invention that the length of the hole is much longer than that obtained by the drilling process.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the entire T culm O of melt flow, Fig. 2 is a cross-sectional view of an embodiment of the present invention, and Fig. 3 is a 3D diagram of Fig. 1 and Fig. 2.
Figure 4 is a front view of the die for Nol 1 flow before it is erected, with a capillary tube placed at the bottom of the die.
FIG. 5 is a cross-sectional view taken along the line 5--5 in FIG. Transverse t by line 6-6 of
Figure 1 is a cross-sectional view similar to Figure 6, showing the capillary tube in position before joining onto one of the die pieces, and shows the two pieces forming the die. Figure 8 shows the condition in which the die is bolted and the item is applied in preparation for heating the solder; FIG. Cross section, No. 9
The figure is a top view of a die with a solder reservoir attached to the machine 1', TM'lJ, and FIG. 10 is an embodiment of the present invention. A cross-sectional view of the die after machining. FIG. 11 is a cross-sectional view of another embodiment of the die of the present invention. 1...Hopper, 2...Extruder, 3.
...Die head, 6...Tube 2 Capillary tube, 1
5, 16...Diflock, 18...
Chamber, A... Apex.

Claims (1)

[Claims] 1. General Q A melt blowing die having a triangular cross section, a die block having a chamber for accommodating a thermoplastic material, and an inner diameter of 254 microns (o, o i . inches) to 635 microns (o. ,025 inches), with an outer diameter of 635 microns (0,025 inches) to 1270 microns (0,050 inches), and a plurality of independent capillary tubes having a smooth inner surface and a uniform diameter, one end and the other end. are held rigidly within said die block, each in substantially planar contact with each other, said other ends containing capillaries disposed in precise alignment to eliminate sharp edges; One end is fluidly connected to the chamber, and the other end of the capillary tube has a pointed end whose cross section is set within the range of 300 to 900 mm, and is configured to fluidly connect with the outside of the dive tool; An upper gas injection passage and a partial gas injection passage are provided to be deoxidized by a gas plate, the tip of the gas plate being spaced parallel to and adjacent to the tip of the capillary tube. 2. A melt-blowing die characterized in that the gas plate is provided so as to maintain the same angle as the pointed end. 2. die.