JPH069847B2 - Method for orienting short fibers of rubber matrix and extended die used therefor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for orienting short fibers of a rubber matrix in which short fibers are three-dimensionally arranged, and an expansion die used for the same.

(Prior Art) Generally, in a rubber matrix containing short fibers, the strength and modulus in the direction of arrangement of the short fibers are particularly large,
In addition, it is known that when a rubber matrix containing short fibers is extruded, the short fibers tend to be arranged in the flow direction (extrusion direction).

By the way, if short fibers can be arranged three-dimensionally in the rubber matrix, the degree of freedom of design is increased by adjusting the ratio, and the range of application is expanded. Particularly, in the case of a V-belt, it is used for the bottom rubber in which short fibers are mainly arranged in the belt width direction. In addition, the bottom rubber is arranged by a few percent in the vertical direction or at a certain angle in the belt longitudinal direction. As a result, it is expected that the belt will be superior in terms of belt life to the conventional one arranged only in the width direction.

However, in the conventional calendering process, the short fibers are two-dimensionally arranged, and more than 90% are arranged in the sheet rolling direction, and about 2% are arranged in the direction orthogonal to the sheet surface, which are three-dimensionally arranged. Is difficult.

Therefore, as described in, for example, Japanese Patent Publication No. 53-14269, the flow passage width of a die attached to an extruder has a predetermined flow passage width from a cylindrical inlet portion to an intermediate portion and has a radius of the inlet portion. Passing through a larger cylindrical outlet part, extruding a rubber matrix containing short fibers into a tube shape with the axis of the extrusion screw as the axial center to increase the orientation ratio of the short fibers in the circumferential direction, and the outlet part The larger the radius expansion ratio (= channel area expansion ratio) between the inlet and the inlet, the higher the orientation ratio in the circumferential direction. Therefore, it is proposed to control the orientation ratio in the axial direction and the circumferential direction. Has been done.

(Problems to be Solved by the Invention) However, the above-described technique is a technique relating to the production of an annular body such as a hose, etc., and the arrangement control of the short fibers in the circumferential direction and the axial direction is performed, and the ratio thereof is expanded. Although it can be adjusted by a ratio, since the flow path width is substantially constant over the entire length, the array of short fibers is not controlled in the radial direction of the annular body, and a three-dimensional array cannot be performed. However, it is not possible to sufficiently expand the range of application.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for orienting short fibers of a rubber matrix, in which short fibers can be ternarily controlled and arranged in a rubber matrix containing short fibers. It is what

It is also an object of the present invention to provide an expansion die for use in the orientation of short fibers of a rubber matrix, which enables control of the three-dimensional arrangement of short fibers in such an orientation method.

(Means for Solving the Problem) The present invention is directed to a flow channel width ratio between an inlet portion and an intermediate portion of an expansion die, a flow channel width ratio between an intermediate portion and an outlet portion, a radius between an inlet portion and an outlet portion, and a cross-sectional area. By controlling the ratio,
In the rubber matrix containing short fibers, the short fibers can be arranged three-dimensionally, and the expansion die can freely control the orientation ratio in the three-dimensional direction by changing the ratio.

The invention of claim (1) uses an extruder equipped with an expansion die, and a cylinder having a predetermined flow passage width, a predetermined flow passage width and a predetermined flow passage width and a radius larger than the inlet space. Through the exit space of the shape, presuming the orientation method of the short fibers of the rubber matrix extruding the rubber matrix containing short fibers as a tubular body with the axis of the extrusion screw of the extruder as the axis, The intermediate space includes an enlarged space portion in which the flow passage width changes from a predetermined flow passage width of the inlet space to a predetermined flow passage width of the outlet space, and the cross-sectional area of the outlet space is larger than the cross-sectional area of the inlet space. The flow path width of the inlet portion is smaller than the flow path width of the intermediate portion, and the flow path width of the outlet portion is less than or equal to the flow path width of the intermediate portion.

According to the invention of claim (2), a rubber matrix containing short fibers is extruded as a tubular body through a tubular space formed by an inner surface of an outer die and an outer surface of the inner die, which is attached to an extruder. Based on the premise of an expansion die used for orientation of short fibers of a rubber matrix having a cylindrical inlet portion with a channel width of, and a cylindrical outlet portion having a larger radius and cross-sectional area than the inlet portion, The inlet part and the outlet part are connected to each other, the center block is provided with an intermediate part having an enlarged space part in which the channel width changes from the channel width of the inlet part to the channel width of the outlet part. The flow passage width Wi, the flow passage width Wc in the middle portion, and the flow passage width Wo in the outlet portion have a relationship of Wc / Wi> 1, Wo / Wc ≦ 1.

And, the invention of claim (3), the enlarged space portion of the intermediate portion is a curved surface which is formed on at least one of the inner surface of the outer die or the outer surface of the inner die and which is curved with respect to the flow direction of the rubber matrix. Composed. In the invention of claim (4), the enlarged space portion of the intermediate portion is formed on at least one of the inner surface of the outer die and the outer surface of the inner die and is inclined at a constant inclination angle α with respect to the flow direction of the rubber matrix. It is composed of inclined surfaces. In the invention of claim (5), the inclination angle α of the intermediate portion has a relationship of α = 10 to 90 °. In the invention of claim (6), the ratio Wc / Wi of the flow passage width Wc of the intermediate portion and the flow passage width Wi of the inlet portion is 1.1 to 5, and the ratio Wo of the outlet portion Wo and the flow passage width Wc of the intermediate portion is Wo. / Wc is 0.6 to 1,
The inclination angle α is 10 to 90 °.

(Operation) According to the invention of claim (1), since the channel width of the inlet portion is narrower than the channel width of the intermediate portion, the orientation ratio of the short fibers in the extrusion direction, that is, the axial direction of the tubular body is increased. . That is, the orientation ratio of the short fibers with respect to the axial direction is controlled by controlling the channel width of the inlet portion.

The rubber matrix sheet buckles when the rubber matrix moves from the inlet part to the intermediate part due to the expanded space part provided in the intermediate part connected to the inlet part, and the degree of change of the expanded space part (the intermediate part and the inlet part). Since the expansion space is filled according to the ratio of the flow path width to the part and the inclination angle, or the curvature radius of the curve), the rubber sheet is regularly folded and laminated to form a laminated shape orthogonal to the extrusion axis direction. As a result, the arrangement of the short fibers is changed from the axial direction to the radial direction. Since the flow of rubber in the circumferential direction occurs due to the expansion of the passage area in the middle portion while the radius expands, the arrangement direction of the short fibers changes to the circumferential direction, and the short fiber arrangement in the radial direction changes. The direction changes in the circumferential direction, and the orientation ratios of the short fibers in the radial direction, the axial direction, and the circumferential direction are controlled.

Further, according to the inventions of claims (2) to (6), since the ratio of the flow passage widths of the intermediate portion and the outlet portion is smaller than 1, so-called throttling is applied when exiting from the outlet portion. , As the degree of narrowing increases, the radial short fibers incline greatly in the axial direction, and as a result, the proportion of axial short fibers increases, and the orientation ratio of axial short fibers is controlled again. .

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.
In the following description of the examples, the Y direction is the orientation direction of the short fibers, the circumferential direction of the tubular body, the X direction is the rubber extrusion direction, the axial direction, and the Z direction is the radial direction of the tubular body.

FIG. 1 shows an expansion die attached to an extruder and having a rubber matrix containing short fibers extruded as a tubular body through an inner surface of an outer die centered on an axis of an extrusion screw and an outer surface of the inner die. The expansion die 1 is composed of an outer die 2, an inner die 3 and a center block 4, and is attached to a spider shaft 6 attached to an extruder 5 with a nut 8 via a spacer 7. 9 is a gauge ring.

The flow channel 11 of the expansion die 1 through which the rubber matrix containing short fibers flows is, as schematically shown in FIG.
The inlet portion 11a (flow passage width Wi) and the outlet portion 11b (flow passage width Wo) communicate with each other through the intermediate portion 11c (flow passage width Wc). That is, the intermediate portion 11c has an inclined surface 11d in which the wall surface of the flow path 11 is inclined at a constant inclination angle α with a constant inclination angle with respect to the flow direction of the rubber matrix, in the vicinity of the connection portion with the inlet portion 11a. The inclined space forms an enlarged space portion.

The flow passage width Wi of the inlet portion 11a, the maximum flow passage width Wc of the intermediate portion 11c, the flow passage width Wo of the outlet portion 11b, and the inclination angle α of the inclined surface of the intermediate portion 11c are Wc / Wi> 1, Wo / The relationship is Wc ≦ 1, α = 10 to 90 °. In that case, in particular, the intermediate portion 11c
Ratio of the maximum channel width Wc of the channel to the channel width Wi of the inlet portion 11a Wc / W
i is 1.1 to 5, the flow passage width Wo of the outlet portion 11b and the intermediate portion 1
The ratio Wo / Wc of the channel width Wc of 1c is 0.6 to 1, and the inclination angle α is 10 to
It has been confirmed from the test results described later that 90 ° is desirable.

Although the inclined surface 11d is formed by the center block 4 on the inner die 3 side in the above embodiment, as shown in FIG. 2, the inclination angle is not on the inner die 3A side but on the outer die 2A side. 12d may be formed, or both dies 2A,
You may make it provide each 3A with an inclined surface. The flow path 12 includes an inlet portion 12a, an outlet portion 12b and an intermediate portion 12c.

According to the above configuration, the flow passage width of the inlet portion 11a and the outlet portion 11b of the flow passage 11 and the inclined surface 1 of the intermediate portion 11c.
By changing the inclination angle α of 1d, it becomes possible to three-dimensionally arrange the short fibers mainly arranged in the circumferential direction, and the sheet thickness becomes substantially constant.

If the flow passage width Wo of the outlet portion 11b becomes larger than the maximum flow passage width Wc of the intermediate portion 11c by a predetermined amount, the flow of the rubber matrix becomes unstable. Therefore, it is necessary to satisfy Wo≤Wc.

To direct the short fibers in the Z direction, the flow path width of the inlet portion 11a
Wi may be extremely small with respect to the maximum flow path width Wc of the intermediate portion 11c, but if Wo <Wc, the short fibers in the Z direction are converted into an orientation inclined along the extrusion axis (X direction), Short fibers in the X direction increase. The degree of this inclination is Wo / Wc
= Cos θ is given by the inclination angle θ. This tilt angle (α = 90
) Does not affect the orientation rate of the short fibers in the Y direction,
As α = 10 ° approaches, the orientation rate of the short fibers in the Y direction tends to slightly decrease. Therefore, it is practically desirable to approach α = 90 °.

That is, in the front of the entrance portion 11a, the directions of the short fibers are random, but in the entrance portion 11a, the direction is the X direction,
In the enlarged space portion formed by the inclined surface 11d of the intermediate portion 11c, as shown in FIG. 4, the rubber matrix 15 buckles to form a laminated shape and fills the enlarged space portion. That is, X
The arrangement of the short fibers is converted in the Z direction orthogonal to the direction, and at the same time, the conversion in the Y direction is also performed in the outlet portion 11b and the inlet portion 1.
It becomes larger according to the ratio of the radius with 1a, Ro / Ui.

If Wo / Wi = Ro / Ri, the orientation direction of the short fibers does not change, but if Wo / Wi> Ro / Ri, it is tilted in the Z direction and Wo /
If Wi <Ro / Ri, it will tilt in the Y direction.

When Wo / Wi = Ro / Ri, the conversion in the Y direction is Ro /
Depends on the ratio of Rc, that is, Ro / Rc is Ro / R
As it approaches i, the conversion rate in the Y direction increases.

Generally, the inclination angle α can be freely selected in the range of 0 to 90 °, but if the flow passage width Wi of the inlet portion 11a is made small, it is temporarily X at the inlet portion 11a. The arrangement in the direction increases, and the proportion of the arrangement in the Z direction is larger than that in the X direction depending on the ratio Wc / Wi of the flow passage widths during the transition from the inlet portion 11a to the intermediate portion 11c. Become.

Then, by the time the outlet portion 11b is reached, Y> Z> X.

Next, when Wo <Wc is set in front of the outlet portion 11b to narrow the channel width, the buckled annular laminate tends to be tilted in the X direction from the Z direction perpendicular to the extrusion surface. As shown in FIG. 5, it is inclined by an angle θ, and this inclination is determined by cos θ.

Further, as shown in FIG. 6, the outer die 2B and the inner die 3B are
The enlarged space portion of the intermediate portion 12c of the flow path 12 formed in [4] may be configured by the curved surface 12e instead of the inclined surface 12d.

Further, in the structure of FIG. 6, Wc is formed at the outlet portion 12b.
Although the diaphragm that moves to Wo is given only on one surface (inclined surface) 12f, as shown in FIG. 7, even if Wo / Wc <1, Wc
The flow passage that moves to Wo is given on both the inside and outside, and α1, α2
When the inclination angle is set as shown in FIG. 8, it is possible to arrange the short fibers in a V shape with respect to the extrusion direction at the center of the central axis of the flow path having a cos θ of Wo, as shown in FIG.
2C is an outer die and 3C is an inner die.

In addition, as shown in FIG. 9, the flow passage 11 through which the rubber matrix flows is such that the intermediate portion 11c of the flow passage 11 constituted by the outer die 2D and the inner die 3D is aligned with the axis of the inlet portion 11a and the outlet portion 11b. You may make it incline by a fixed angle.

Next, the test results of the die 1 will be described.

Test 1 Using an extruder having a diameter of 90 mm, a die temperature was set to 100 °, and a screw rotation speed was set to 10 rpm, and a test was conducted on a rubber matrix containing a rubber compound described later. In addition, Ro / Ri = 6.5,
α = 15 °.

Rubber compounding neoprene G type 100 carbon black 20 oil 4 short fibers (aspect ratio 100) 13 others 12 The test results are shown in Table 1. That is, for each Wi
X + Z is increasing with increasing Wo / Wi ratio. Wo / Wi
The difference between Z and X becomes larger due to the decrease of Z, and the conversion from Z to X is presumed.

Test 2 This test is a test on the relationship between the position of the expansion die and the arrangement state of the short fibers.

The test results are shown in Table 2.

That is, the umbrella-shaped rubber left between the outer die and the inner die is taken out and vulcanized, and the orientation ratio is determined from the swelling degree at the points of 40 mm, 80 mm and 120 mm from the die entrance to the outside of the die. Has been calculated. The relationship between Wo / Wi is not clear, but Wi
The change between ~ Wc is clear.

Test 3 The conditions were the same as in Test 1, and the relationship between Wi and Wc and the orientation rate was tested. However, Wi = 3 mm and α = 15 °.

The test results are shown in Table 3 and FIG. That is, the most preferable range is Wc / Wi = 1-5, Wo / Wc
= 1 to 0.6 holds.

In FIG. 10, the range of S ₁ is 90% or more in the Y direction, which is outside the range required by the present invention. The range of S ₂ is 60% or less in the Y direction and 35% or less in the Z direction, which is outside the required range.

Test 4 Under the same conditions as Test 1, Wc / Wi = 1.7, Wo / Wc = 0.6 (Test 3
In D), the value was changed in the range of α = 10 to 90 °.
The relationship in the X, Y, and Z directions did not change much.

By the way, the orientation ratio was measured by vulcanizing the extruded product, punching out a test piece of 37 mm in diameter, immersing it in toluene at room temperature for 50 hours and measuring the swelling degree in the three-dimensional direction, and taking the reciprocal percentage. Was used as the orientation rate.

A, B and C are swelling degrees in X, Y and Z directions, and M, N and O are orientation rates in X, Y and Z directions.

M = 100 / (A-1) / L N = 100 / (B-1) / L O = 100 / (C-1) / L where L = 1 / (A-1) + 1 / (B- 1) + 1 / (C-1).

(Effect of the invention) According to the invention of claim (1), as described above, in the intermediate space, the flow passage width changes from the predetermined flow passage width of the inlet space to the predetermined flow passage width of the outlet space. A space is provided, and the cross-sectional area of the outlet space of the expansion die is formed larger than the cross-sectional area of the inlet space by a predetermined amount. Further, the flow passage width of the inlet portion is narrower than the flow passage width of the intermediate portion, and the flow passage of the outlet portion is formed. Since the width is set to be equal to or smaller than the flow path width of the intermediate portion, the short fibers can be arranged three-dimensionally, and the properties of the rubber matrix can be changed over a wide range.

Further, according to the inventions of claims (2) to (6), such a short fiber can be easily arranged three-dimensionally only by attaching it to the extruder.

[Brief description of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a sectional view of an expansion die. FIG. 2 is a schematic view of an expansion die, FIG. 3 is a view similar to FIG. 2 of a modified example, FIG. 4 is a view showing a buckling state of a seat, and FIG. 6 and 7 are explanatory views of a modified example, FIG. 8 is a sectional view of a seat, and FIG.
FIG. 10 is a diagram showing another embodiment of the expansion die, and FIG. 10 is a diagram showing test results. 1 ... Expansion die, 2, 2A, 2B, 2C, 2D ... Outer die,
3, 3A, 3B, 3C, 3D ... Inner die, 11, 12 ... Channel, 11a, 12a ... Inlet portion, 11b, 12b ... Outlet portion, 11c, 12c ... Intermediate portion

Claims (6)

[Claims] 1. A cylindrical outlet space having a predetermined channel width and a predetermined channel width and a radius larger than that of the inlet space, using an extruder equipped with an expansion die, and having a predetermined channel width, a cylindrical inlet space, an intermediate space, and an intermediate space. In the method of orienting the short fibers of the rubber matrix, wherein the rubber matrix containing the short fibers is extruded as a tubular body having the axis of the extrusion screw of the extruder as the axis, and the intermediate space has a predetermined inlet space. From the flow passage width of the outlet space to the predetermined flow passage width of the outlet space is provided, the cross-sectional area of the outlet space is formed a predetermined amount larger than the cross-sectional area of the inlet space, A method for orienting short fibers of a rubber matrix, wherein the flow channel width is narrower than the flow channel width of the intermediate portion, and the flow channel width of the outlet portion is not more than the flow channel width of the intermediate portion. 2. A rubber matrix containing short fibers is extruded as a tubular body through a tubular space formed by an inner surface of an outer die and an outer surface of the inner die, which is attached to an extruder, and has a predetermined flow passage width. In an expansion die used for the orientation of short fibers of a rubber matrix comprising a cylindrical inlet part and a cylindrical outlet part having a larger radius and cross-sectional area than the inlet part, the inlet part and the outlet part are connected to each other. A center block forming an intermediate portion having an enlarged space portion whose flow passage width changes from the flow passage width of the inlet portion to the flow passage width of the outlet portion, the flow passage width Wi of the inlet portion, the flow passage of the intermediate portion An expansion die used for orientation of short fibers of a rubber matrix, wherein the width Wc and the flow path width Wo of the outlet portion have a relationship of Wc / Wi> 1 and Wo / Wc ≦ 1. 3. The expansion space of the intermediate portion is formed by a curved surface formed on at least one of the inner surface of the outer die and the outer surface of the inner die and curved with respect to the flow direction of the rubber matrix. An expansion die used for the orientation of short fibers of the rubber matrix according to the item (2). 4. The enlarged space portion of the intermediate portion is an inclined surface which is formed on at least one of the inner surface of the outer die and the outer surface of the inner die and is inclined at a constant inclination angle α with respect to the flow direction of the rubber matrix. An expansion die for use in orienting short fibers of a rubber matrix according to claim (2), which is configured as follows. 5. The expansion die used for the orientation of short fibers of a rubber matrix according to claim 4, wherein the inclination angle α of the intermediate portion has a relationship of α = 10 to 90 °. 6. A flow passage width Wc at an intermediate portion and a flow passage width Wi at an inlet portion
The ratio Wc / Wi is 1.1 to 5, the ratio Wo / Wc of the flow passage width Wc of the outlet portion Wo to the intermediate portion is 0.6 to 1, and the inclination angle α is 10 to 90 °. ) An expansion die used for the orientation of short fibers of the rubber matrix described in (1).