JP2006142714A - Feed block - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a feed block the maintenance of which is easy because of a simple structure and which dissolves the interlayer instability phenomenon at the time of coextrusion molding to afford a product stable in appearance quality. <P>SOLUTION: In the feed block used for coextrusion molding wherein resin materials that flow through a plurality of resin flow passages are made to be laminar flow and to join, a widening part is equipped for at least either of the resin passages, the widening part which, near the junction between one resin passage and another resin passage, gradually widens the passage width toward the junction. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a feed block used for multilayer coextrusion molding.

In order to achieve a desired function, a resin film is laminated with a plurality of different resin materials in the thickness direction, or in order to reduce costs, a recovered resin material or a low-cost resin material is placed in an intermediate layer. There are multi-layered resin films.
Such a multilayer resin film is generally manufactured using a co-extrusion molding method in which two or more kinds of resin materials are made into a multilayered monolithic product using a feed block or a multi-manifold die.

  By the way, in the co-extrusion molding as described above, a phenomenon called an interlayer instability phenomenon occurs in the feed block in the actual molding process, and this phenomenon causes a phenomenon at the laminated interface of the product 100 as shown in FIG. A wavy appearance defect may occur and the appearance quality may deteriorate.

Causes of this interlayer instability phenomenon include a difference in viscosity of the resin material forming each layer, a difference in extrusion flow rate of the resin material forming each layer, and the like.
That is, a case where the resin 211 is flowed from one resin flow path 210 of the feed block 200 and the resin 221 is flowed from the other resin flow path 220 using the feed block 200 shown in FIG. When the flow rate is higher than the extrusion flow rate of the resin 221, a force in the normal direction is applied to the resin 221 from the resin 211 at the junction 230, causing the resin 221 to flow in an unstable manner, and an interlayer instability phenomenon occurs.

Therefore, as a means for solving the interlayer instability phenomenon, as shown in FIG. 10, a method of providing a stress relaxation partition plate 310 in the feed block 300 and dealing with this instability phenomenon has been proposed (for example, (See Patent Documents 1 and 2).
However, in the structure of the feed block 300, the thin partition plate 310 vibrates during pressure fluctuations or extrusion fluctuations that occur in extrusion molding, and as a result, the resin pulsates, so that stable film formation can be performed. Can not. In particular, in a film or sheet that requires a thickness accuracy, the pulsation of the resin leads to a thickness variation in the film flow direction, which causes a problem in quality. In addition, since the thin partition plate extends for a long time, the workability of disassembly and cleaning deteriorates, and there is a problem with respect to maintenance.

Japanese Patent No. 2668843 JP-A-7-32443

  In view of the above circumstances, the present invention has a simple structure and is easy to maintain, and can eliminate a phenomenon of instability between layers at the time of coextrusion molding to obtain a product having a stable appearance quality. The purpose is to provide.

In order to achieve the above object, a feed block according to the present invention is a feed block used for co-extrusion molding in which resin materials flowing through a plurality of resin flow paths are layered and joined together. In the vicinity of the junction with the path, at least one of the resin channels is provided with a widened portion that gradually widens the channel width toward the junction.

  In the present invention, the widened portion is provided in a resin flow path in which a resin material having a larger extrusion flow rate than the resin material flowing in the other resin flow path to be merged, or in the other resin flow path to be merged. It is preferable to be provided in a resin flow path through which a resin material having a viscosity higher than that of the resin material flowing.

  As described above, the feed block according to the present invention is a feed block used for co-extrusion molding in which resin materials flowing in a plurality of resin flow paths are layered and joined together. In the vicinity of the merge point, since the widened portion that gradually widens the flow path width toward the merge point is provided in at least one of the resin flow paths, the interlayer instability phenomenon during coextrusion molding is eliminated, A product with stable appearance quality can be obtained. And since it is a simple structure which only provides the wide part in the confluence | merging point vicinity of a resin flow path, maintenance is easy.

Hereinafter, the present invention will be described in detail with reference to the drawings showing embodiments thereof.
1 and 2 illustrate a first embodiment of a feed block according to the present invention.

As shown in FIGS. 1 and 2, the feed block 1 includes two resin flow paths 11 and 12 inside.
And as shown in FIG. 2, the two resin flow paths 11 and 12 are extruded and supplied from individual extruders (not shown) on the upstream side, respectively, It merges at the downstream junction 14 and forms a layer after the merge and is pushed out toward a mold (not shown).

Moreover, one resin flow path 11 of these two resin flow paths 11 and 12 has a larger extrusion flow rate of the resin material A flowing inside than the other resin flow path 12, and the other resin flow path In the vicinity of the junction 14 with the path 12, a widened portion 13 that gradually widens toward the junction 14 is provided.
The widened portion 13 is 1 mm ≦ a ≦ 5 mm, 1 mm ≦ b ≦ 3 mm, where a is the dimension in the resin flow direction of the widened portion 13, b is the amount of widening of the widened portion 13, and c is the taper angle of the widened portion 13. It is formed so as to satisfy 5 ° ≦ c ≦ 45 °.

If the widened portion 13 is gradually widened, the shape of the widened portion is not particularly limited. However, as shown in FIG. 1, the dimension of the widened portion 13 in the resin flow direction is a, and the widened amount of the widened portion 13 is increased. b, where c is the taper angle of the widened portion 13, 1 mm ≦ a ≦ 5 mm, 1 mm ≦ b ≦ 3 mm, and 5 ° ≦ c ≦ 45 ° are preferable.
That is, if the dimension a in the resin flow direction is less than 1 mm, the stress of the resin material A cannot be relaxed and normal stress is applied from the resin material A to the resin material B at the junction with the resin material B. If it exceeds 5 mm, the flow of the resin is not stable, and there is a risk of causing fluctuations in extrusion amount and pressure fluctuations.

If the widening amount b of the widened portion 13 is less than 1 mm, the stress of the resin material A may not be alleviated and normal stress may be applied from the resin material A to the resin material B at the junction with the resin material B. If it exceeds 3 mm, the flow of the resin is not stable, and there is a possibility of causing fluctuations in extrusion amount and pressure fluctuations.
If the taper angle c of the widened portion 13 is less than 5 °, the stress of the resin material A is not alleviated and normal stress is applied from the resin material A to the resin material B at the junction with the resin material B. If it exceeds 45 °, the flow of the resin is not stable, and there is a risk of causing fluctuations in the extrusion amount and pressure fluctuations.

  Further, the resin material B is joined to the other resin flow path 12 from an oblique direction with respect to the resin flow direction of the one resin flow path 11.

  And according to this feed block 1, as shown in FIG. 2, since the resin flow path 11 is provided with the widening part 13 which gradually widens toward the confluence 14 in the vicinity of the confluence 14, at the confluence, The force in the normal direction is not applied to the resin material B from the resin material A, and the resin material B does not cause unstable flow.

FIG. 3 shows a second embodiment of the feed block according to the present invention.
As shown in FIG. 3, the feed block 2 includes three resin flow paths 21, 22, and 23.
And the resin flow path 22 provided in the center is such that the maximum flow rate of the resin material A flows, and in the vicinity of the merge point with the other two resin flow paths 21, 23, the respective merge points 24, The feed block 1 is the same as the feed block 1 except that wide portions 26 and 27 that gradually widen toward 25 are provided.

FIG. 4 shows a third embodiment of the feed block according to the present invention.
As shown in FIG. 4, in the feed block 3, the resin flow direction immediately before joining the resin flow path 31 provided with the widened portion 33 is inclined with respect to the resin flow direction after joining at the joining point 34. The flow path is the same as that of the feed block 1 except that the resin flow direction immediately before the merge of the resin flow path 32 not provided with the widened portion substantially coincides with the resin flow direction after the merge at the merge point 34.

FIG. 5 shows a fourth embodiment of the feed block according to the present invention.
As shown in FIG. 5, the feed block 4 has a resin channel 41 provided with the widened portion 43 and a resin flow channel 42 provided with no widened portion immediately before joining at the junction 44. The resin flow direction is the same as that of the feed block 1 except that the resin flow direction substantially coincides with the resin flow direction after joining.

FIG. 6 shows a fifth embodiment of the feed block according to the present invention.
As shown in FIG. 6, the feed block 5 includes three resin flow paths 51, 52, and 53, a junction 54 between the resin flow path 51 and the resin flow path 52, a resin flow path 53 and the resin flow path 52. Are formed at the tips of the vanes 56 and 57, respectively, and the tips of the vanes 56 and 57 on the resin flow path 52 side are notched to form widened portions 58 and 59. In addition, the feed block 2 is the same as the feed block 2 except that the notches at the tips of the vanes 56 and 57 are asymmetrical.

The feed block of the present invention is not limited to the above embodiment. For example, in the above embodiment, there are two or three resin flow paths, but four or more resin flow paths may be provided. In the above embodiment, the confluence of the central resin flow path and the resin flow paths on both sides is provided at the same position in the resin flow direction, but the two merge points are shifted in the resin flow direction. It doesn't matter.
In the case of the feed block 5, the notches at the tips of the vanes 56 and 57 are asymmetrical, but they may be symmetrical.

  Specific examples of the present invention will be described below.

<Example 1>
Using the feed block 5 shown in FIG.
Ethylene / Butylene Block Copolymer (trade name “Clayton G1657 manufactured by Shell Chemical Co., Ltd.)
)) Is supplied at an extrusion flow rate of 2 kg / hr, and low-density polyethylene (trade name “Mirason 12” manufactured by Mitsui Chemicals, Inc.) is supplied to the resin flow path 52 at an extrusion flow rate of 18 kg / hr.
A three-layer film was formed. The mold is a straight manifold type (width 380mm
) And the set temperature was 190 ° C.
As a result of visual determination of the obtained three-layer film, the film produced under these conditions did not have a poor appearance due to unstable flow.
In addition, the dimension of each part of the feed block 5 was as showing in FIG.

<Example 2>
Low-density polyethylene (trade name “Mirason 12” manufactured by Mitsui Chemicals, Inc.) is extruded into the resin flow path 51 at an extrusion flow rate of 1 kg / hr, and low-density polyethylene (trade name “Mirason 12” manufactured by Mitsui Chemicals, Inc.) is applied to the resin flow path 52. Except that the styrene-ethylene-butylene block copolymer (trade name “Clayton G1657” manufactured by Shell Chemical Co., Ltd.) was supplied to the resin flow path 53 at an extrusion flow rate of 2 kg / hr, respectively, at an extrusion flow rate of 7 kg / hr. Thus, a three-layer film was formed.
As a result of visual determination of the obtained three-layer film, the film produced under these conditions did not have a poor appearance due to unstable flow.

<Example 3>
Low density polyethylene (trade name “Mirason 12” manufactured by Mitsui Chemicals, Inc.) is extruded into the resin flow path 51 at an extrusion flow rate of 2 kg / hr, and low density polyethylene (trade name “Mirason 12”, manufactured by Mitsui Chemicals, Inc.) is applied to the resin flow path 52. Except that the styrene-ethylene-butylene block copolymer (trade name “Clayton G1657” manufactured by Shell Chemical Co., Ltd.) was supplied to the resin flow path 53 at an extrusion flow rate of 2 kg / hr, respectively, at an extrusion flow rate of 8 kg / hr. Thus, a three-layer film was formed.
As a result of visual determination of the obtained three-layer film, the film produced under these conditions did not have a poor appearance due to unstable flow.

<Example 4>
Using the feed block 5 shown in FIG. 6, polybutylene terephthalate (trade name “Duranex 700FP”, manufactured by Polyplastics Co., Ltd., drying condition: 120 ° C. × 4 hours) is extruded into the resin flow path 51 and the resin flow path 53, respectively. / hr, ethylene-ethyl acrylate copolymer resin (trade name “EVAFLEX A-7 made by Mitsui DuPont Polychemical Co., Ltd.)
12 ") at an extrusion flow rate of 10 kg / hr, respectively, to form a three-layer film having a width of 300 mm. The mold was a straight manifold type (width 380 mm) and the set temperature was 250 ° C.
As a result of visual determination of the obtained three-layer film, the film produced under these conditions did not have a poor appearance due to unstable flow.

<Example 5>
Example 4 except that low density polyethylene (trade name “Petrocene 173R” manufactured by Tosoh Corporation) was used instead of ethylene-ethyl acrylate copolymer resin (trade name “EVAFLEX A-712” manufactured by Mitsui DuPont Polychemical Co., Ltd.) Similarly, a three-layer film was obtained.
As a result of visual determination of the obtained three-layer film, the film produced under these conditions did not have a poor appearance due to unstable flow.

<Comparative Example 1>
3 except that the feed block 5a provided with vanes 58a and 59a not provided with the widened portion shown in FIG. 7 is used instead of the feed block 5 shown in FIG.
A layer film was produced. As a result of visual judgment of the obtained three-layer film, the film produced under these conditions had a poor appearance due to unstable flow.
The dimensions of each part of the feed block 5a were as shown in FIG.

<Comparative example 2>
3 except that the feed block 5a provided with vanes 56a and 57a not provided with the widened portion shown in FIG. 7 is used instead of the feed block 5 shown in FIG.
A layer film was produced. As a result of visual judgment of the obtained three-layer film, the film produced under these conditions had a poor appearance due to unstable flow.

<Comparative Example 3>
3 except that the feed block 5a provided with vanes 58a and 59a not provided with the widened portion shown in FIG. 7 is used instead of the feed block 5 shown in FIG.
A layer film was produced. As a result of visual judgment of the obtained three-layer film, the film produced under these conditions had a poor appearance due to unstable flow.

<Comparative example 4>
3 except that the feed block 5a provided with vanes 58a and 59a not provided with the widened portion shown in FIG. 7 is used instead of the feed block 5 shown in FIG.
A layer film was produced. As a result of visual judgment of the obtained three-layer film, the film produced under these conditions had a poor appearance due to unstable flow.

<Comparative Example 5>
3 except that the feed block 5a provided with vanes 58a and 59a not provided with the widened portion shown in FIG. 7 is used instead of the feed block 5 shown in FIG.
A layer film was produced. As a result of visual judgment of the obtained three-layer film, the film produced under these conditions had a poor appearance due to unstable flow.

It is principal part sectional drawing of 1st Embodiment of the feed block concerning this invention. It is sectional drawing explaining the flow of the resin at the time of using the feed block of FIG. It is principal part sectional drawing explaining the flow of the resin of 2nd Embodiment of the feed block concerning this invention. It is principal part sectional drawing explaining the flow of the resin of 3rd Embodiment of the feed block concerning this invention. It is principal part sectional drawing explaining the flow of the resin of 4th Embodiment of the feed block concerning this invention. It is principal part sectional drawing of 5th Embodiment of the feed block concerning this invention. It is principal part sectional drawing of the feed block used for the comparative example. It is explanatory drawing explaining the external appearance defect of the resin film which generate | occur | produces by an interlayer instability phenomenon. It is sectional drawing explaining the flow of the resin in the resin confluence | merging part of the conventional feed block. It is principal part sectional drawing of a well-known feed block.

Explanation of symbols

1, 2, 3, 4, 5 Feed blocks 11, 12, 21, 22, 23, 31, 32, 41, 42, 51, 52, 53 Resin passages 13, 26, 27, 33, 43, 56, 57 Widened portion 14, 24, 25, 34, 44, 54, 55 Junction point A, B Resin material

Claims (3)

In a feed block used for coextrusion molding in which resin materials flowing through a plurality of resin flow paths are combined in layers,
A feed block characterized in that at least one of the resin flow paths is provided with a widened portion that gradually widens the flow path width toward the merge point in the vicinity of the merge point between the resin flow path and the resin flow path. .   The feed block according to claim 1, wherein the widened portion is provided in a resin flow path in which a resin material having a larger extrusion flow rate than a resin material flowing in the other resin flow path that joins.   The feed block according to claim 1 or 2, wherein the widened portion is provided in a resin flow path in which a resin material having a higher viscosity than a resin material flowing in the other resin flow path that joins.

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