JPH0490317A - Manufacture of staple fiber composite rubber product - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for manufacturing short fiber composite rubber products.

(Prior Art) In general, methods for orienting short fibers in short fiber composite rubber include a calender molding method and an extrusion molding method.

A composite rubber sheet with short fibers oriented in the grain direction by calender molding, and a method in which the short fibers are oriented off the extrusion axis by extrusion molding (for example, Japanese Patent Publication No. 5B-
14269) and a method for manufacturing an extruded hose in which the radial component of fiber orientation exceeds the circumferential component of fiber orientation (see, for example, Japanese Patent Publication No. 58-29231).

(Problem to be Solved by the Invention) However, in order to obtain a short fiber composite rubber product using the above-mentioned method, it is necessary to perform compression vulcanization molding after preforming such as cutting and lamination, or to perform cutting after vulcanization. Requires complicated processes such as cutting out.

The present invention provides a manufacturing method that can efficiently, inexpensively, and stably manufacture short fiber composite rubber products having the main orientation direction of the short fibers, which requires complicated steps.

(Means for Solving the Problem) The invention as claimed in () is a method of injecting short fiber-containing rubber into a cavity of a molding die through a rubber inlet. A method for manufacturing a short fiber composite rubber product having a maximum fiber orientation ratio, wherein the rubber inlet has an elongated slit shape, and the height thereof is equal to or 1 of the height of the cavity surface with which the rubber inlet communicates. 2 or less and 2mo+ or less.

The invention of claim (2) provides a short fiber composite having a maximum fiber orientation ratio in the direction corresponding to the direction of expansion of the inlet by injecting short fiber-mixed rubber into the cavity of a molding die through the rubber inlet. A method of manufacturing a rubber product, the method comprising:
The ratio of the exit width to the minimum width of the rubber inlet is 2 or more, the ratio of the height of the exit part to the height of the minimum width part is 2 or less, and the ratio of the area of the exit part to the area of the minimum width part is 2 or more, The outlet end face of the rubber inlet is configured to match one molding surface of the cavity of the molding die.

(Function) According to the invention of claim (1), the rubber inlet has an elongated slit shape, and the height thereof is 1/2 or less of the height of the cavity surface with which the rubber inlet communicates and 2 cm or less. Therefore, either the short fibers that are once oriented in the flow direction at the rubber inlet or the sudden expansion of the rubber flow path in the direction corresponding to the height of the rubber inlet when flowing into the cavity cause the short fibers to flow in that direction. The short fibers are oriented, and a short fiber composite rubber product is produced which has the maximum fiber orientation rate in the direction corresponding to the height direction of the inlet.

According to the invention of claim (2), the ratio of the outlet width to the minimum width of the rubber inlet is 2 or more, the ratio of the height of the outlet part to the height of the minimum width part is 2 or less, and the area of the minimum width part is Since the ratio of the area of the outlet part is 2 or more and the end face of the outlet part of the rubber inlet corresponds to one molding surface of the cavity of the molding die, the short fibers gradually grow in the direction of expansion of the inlet at the rubber inlet. A short fiber composite rubber product is produced which has a maximum fiber orientation ratio in the direction corresponding to the inlet expansion direction.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

Example 1 - This example is a method of obtaining maximum fiber orientation in the slit thickness direction using a slit-shaped inlet (so-called film gate).

In FIGS. 1 and 2 showing a molding die, reference numeral 1 denotes a molding die, into which short fiber composite rubber is supplied into a cavity 2 through a rubber inlet port 3. In FIG. The rubber inlet portion 3 includes an artificial portion 3a having a substantially circular cross section, and an inlet portion 3.
a i: Continuous slit portion 3 whose passage cross section is elongated in the horizontal direction
It has b. The height (distance in the Z direction) of the rubber inlet portion 3 (slit portion 3b) is 21 or less, and is less than or equal to 1/2 of the cavity height L2 in two directions of the cavity 2 to which the rubber inlet portion 3 is connected. By setting (L, ≦L2/2), a short fiber composite rubber body having the maximum fiber orientation ratio in the Z direction can be obtained.

FIG. 3 is a diagram showing only the short fiber composite rubber body 5 taken out after filling with the short fiber composite rubber is completed. After completion of vulcanization, the product is taken out from the mold and the excess rubber 6 corresponding to the rubber inlet portion 3 is removed to obtain the final short fiber composite rubber product.

Note that if the height L of the slit portion 3b exceeds 2 mm, or if Ll>L2/2, the maximum fiber orientation in the Z direction cannot be obtained.

Embodiment 2 - In this example, the rubber inlet is expanded in the width direction, and the outlet is filled with short fiber composite rubber through the rubber inlet, which becomes one surface of the mold cavity. This is the method to obtain maximum fiber orientation.

As shown in FIGS. 4 and 5, the rubber inflow port 13 into the cavity 12 of the mold 11 gradually moves in the width direction from an inlet 13a having the minimum width to an outlet 13b having a size corresponding to one surface of the cavity 12. It is configured to expand to. ■The relationship between the minimum width L3 (inlet 13a) and the width L4 of the outlet 13b is L3≦L4/2, and ■The minimum width of the entrance 13a
The relationship between the height L5 of the outlet 13b and the height L6 of the outlet 13b is ≧L6
/2, and (1) the passage cross-sectional area of the inlet 13a is 1/2 or less of the passage cross-sectional area of the outlet 13b, and (2) the cross-section of the outlet 13b is made to match one molding surface of the cavity 12 (one surface of the final product). , it is possible to obtain a product having the maximum fiber orientation rate in the Y direction.

FIG. 6 is a diagram showing only the short fiber composite rubber body 15 taken out after filling has been completed. After the vulcanization is completed, the final product can be obtained by removing the rubber from the mold 11 and removing the excess rubber 16 having a shape corresponding to the rubber inlet 13.

Note that maximum orientation in the width direction cannot be obtained in a rubber inlet portion (rubber flow path) that does not satisfy any of the conditions (1) to (2) described above.

In order to obtain the desired product using the molds 1 and 11 of Examples 1 and 2 above, injection molding or transfer molding is necessary as the injection and vulcanization means. The injection conditions and transfer conditions are arbitrarily set depending on the characteristics of the short fiber composite rubber compound and the mold shape.

In addition, in the above embodiments, the product is molded from short fiber rubber alone, or after the insert material is installed in the cavity,
It is also possible to fill it with short fiber composite rubber and integrally mold it. In that case, by creating a channel structure in which only the space (rubber filling part) excluding the part occupied by the insert member is used as a cavity, short fiber composite rubber products with the maximum orientation ratio in the height or width direction can be created. Obtainable.

The short fiber composite rubber product produced in this way exhibits anisotropy in the elastic modulus of the short fiber composite rubber portion, and also has a high elastic modulus that cannot be obtained with ordinary rubber in which the short fibers are oriented in one direction. Therefore, when used as a cushioning rubber, a vibration isolating rubber, etc., members such as a stopper are not required, and it is extremely advantageous in reducing weight and size.

Further, the rubber inlet port for supplying the short fiber composite rubber into the cavity of the molding die does not necessarily have to be on the -plane, but as long as it satisfies the above conditions, for example, as shown in FIG. The short fiber composite rubber may be supplied into the cylindrical cavity 22 of the molding die 21 through the rubber inlet portion 23 consisting of the main passage 23a, the planar disk-shaped enlarged passage 23b, and the slit portion 23c. . in this case,
As shown in FIG. 8, the short fibers 24a of the molded product 24 are oriented in the radial direction. The thickness of the slit portion 23c is L7,
The thickness of the cavity 22 is L8.

Further, as shown in FIG. 9, one end of the cylindrical cavity 26 of the mold 25 is communicated with a disc-shaped communication part 27, and a short fiber composite rubber is connected to the center of the communication part 27 through a rubber inlet 28. may also be supplied. In this case, as shown in FIG. 10, the short fibers 29a of the molded product 29 are oriented in the circumferential direction. The diameter of the rubber inlet portion 28 is L9, and the thickness of the communication portion 27 is L9. , the outer diameter of the cavity 26 is L1□.

Furthermore, the flow path axis does not need to be a straight line, but may be a curved line or a broken line. Particularly under high-speed injection conditions, it is effective to change the flow axis by once colliding with a wall surface in the flow path. For example, the 11th
As shown in the figure and FIG. 12, the cavity 3 of the mold 31
A rubber inlet portion 33 is formed in a direction perpendicular to the axis of 2,
The rubber may be supplied through an enlarged passage 34 whose passage area gradually expands until it has the same cross-sectional area as the end face of the cavity 32. In this case, as shown in FIG. 13, the short fibers 35g of the molded product 35 are oriented in the width direction. The rubber inlet portion 33 has a length L12. With a rectangular cross section of L12, the end face of the cavity 32 communicating with the enlarged passage 34 has a width of L12 and a height of L12. Moreover, as shown in FIG. 14, instead of providing an enlarged passage, the rubber is supplied into the cavity 37 of the mold 36 through the slit part 39 from the rubber inlet part 38 in the direction perpendicular to the axis of the cavity 37. Good too.

In this case, as shown in FIG. 15, the short fibers 40a of the molded product 40 are oriented in the thickness direction.

Next, experiments conducted on the short fiber composite rubber product as described above will be explained.

The following formulation was mixed using a Banbury mixer to uniformly disperse short fibers, and then rolled into a sheet using rolls to obtain a test material.

Natural rubber 100 parts by weight Carbon black 40 Softener
5 stearic acid
Zinc monoxide 3 Anti-aging agent
2 wax
2 Accelerator CBS 1
Sulfur 266 nylon short fiber 20 (fiber length 3 mm) The fiber orientation rate was measured from the center of the vulcanized rubber at 20X20X.
A sample of 5o+n+ was taken out by cutting and polishing, and immersed in toluene for 48 hours at room temperature in three directions (x, y).

The coefficient of linear expansion (%) L in two directions was measured, and the fiber orientation ratio Hi in each direction was determined using the following formula.

Hi=[(1/Lf)/f(1/Lx)+(1/Ly)
+ (1/I, z) l rice 100i x, y, z Experiment 1> Cavity size: 50 x 100 x 10 (m
m) (L2=10aim) A mold 1 (divided into an upper plate, a middle plate, and a lower plate) having the structure shown in FIG. Figure 16 shows the measurement results of the fiber orientation ratio. It can be seen that Ll is highly oriented in the Z direction at 2IllIg or less.

Experiment 2> In Experiment 1, Ll was fixed at 2!1I11, metal plates of the same thickness were attached to the upper and lower surfaces of cavity 2, and injection molding was performed while changing Ll.

FIG. 17 shows the measurement results of the short fiber orientation ratio. It can be seen that the maximum fiber orientation rate is shown in the Z direction when LlL2 is 1/2 or less (L2≧4).

Experiment 3> Cavity size: 50X70X7mm (Ll4-5
A mold having the structure shown in FIGS. 11 and 12 (0, Ll5-7) was created, and the minimum width L1□ and width L14 were changed and transfer molded (vulcanization time 160°C, 10 minutes).
I did it.

The following table shows the measurement results of fiber orientation ratio.

L, 4/L, □≧2, L15/L+3≦2, L1
It can be seen that the fiber orientation ratio is maximum in the width direction under the conditions of 2.L+s/L and □.L13≧2.

Experiment 4> In the mold 21 shown in Fig. 7, L7-0.8ml1
．． A cylinder having an outer diameter of 40a+ID and a length of 50mm was made by injection molding, with a length of L8m and 10ma+. A sample for swelling measurement was prepared by cutting in the circumferential direction, and a cubic body with a side of 7) was cut out to measure the compressive elastic modulus in three directions.

A highly anisotropic rubber bushing can be produced by similarly filling the gap with short fiber composite rubber.

Experiment 5> In the molding die 25 shown in Fig. 9, the minimum channel width L9 (diameter) -3■, L+o-3111111, Lll-40+
n.

A cylinder with a wall thickness of 101II11 and a length of 50I1O1 was made by injection molding.

The same measurements as in Experiment 4 were performed.

It is a vulcanized rubber molded product that has the maximum fiber orientation rate in the radial direction and has a higher spring constant in the radial direction and lower spring constant in the length and circumferential directions than non-oriented rubber. When inserted, the fiber orientation rate is maximum in the circumferential direction, and the elastic modulus is highly influenced.

(Effect of the invention) The invention of claim (1) has a rubber inlet having an elongated slit shape, and the height of the rubber inlet is 1/2 or less of the height of the cavity surface with which the rubber inlet communicates and 2 cm or less. As the rubber flow path suddenly expands in the direction corresponding to the height direction of the rubber inlet when flowing into the cavity, the short fibers are oriented in that direction, and the short fibers are oriented in the height direction of the inlet. It is possible to easily produce a short fiber composite rubber product having the maximum fiber orientation rate in the direction corresponding to .

The invention of claim (2) provides a rubber inflow port in which the ratio of the exit width to the minimum width of the rubber inlet is 2 or more, the ratio of the height of the exit part to the height of the minimum width part is 2 or less, and the exit part to the minimum width part area. The ratio of the areas is 2 or more, and the end face of the outlet of the rubber inlet is aligned with one molding surface of the mold cavity.
The short fibers are gradually oriented in the direction of expansion of the inlet at the rubber inlet, and a short fiber composite rubber product having the maximum fiber orientation ratio in the direction corresponding to the direction of expansion of the inlet can be produced.

[Brief explanation of drawings]

The drawings show embodiments of the invention, and FIGS.
Fig. 1 is a front view of the molding die, Fig. 2 is a plan view thereof, Fig. 3 is a perspective view of the molded product, and Figs.
The figure shows the second embodiment, and FIG. 4 is a front view of the molding die.
FIG. 5 is a plan view of the same, and FIG. 6 is a perspective view of the molded product. 7 and 8 show other embodiments, FIG. 7 is a sectional view of the molding die, FIG. 8 is a perspective view of the molded product, and FIGS. 9 and 10.
The figures show still another embodiment, with FIG. 9 being a sectional view of the molding die, and FIG. 10 being a perspective view of the molded product. 11 to 13 show modified examples, in which FIG. 11 is a plan sectional view of the mold, FIG. 12 is a side sectional view of the same, and FIG. 13 is a perspective view of the molded product. FIGS. 14 and 15 show still another modification, in which FIG. 14 is a side sectional view of the molding die, and FIG. 15 is a perspective view of the molded product. FIG. 16 and FIG. 17 are diagrams showing the test results. 1.11.21, 25, 31.38...Molding mold 2.12, 22.2B, 32.37...Cavity 3.13, 23.2g, 33.38.・・・・・・
Rubber inlet portions 3b, 23e, 39...Slit portions 5.15...Short fiber composite rubber body 24.29,
35.40... Molded product 1.11.21.25.
31.36...-Molding mold 2.12.22.2G, 32
．． 37... Cavity LL3.23.28.33.
38...Rubber inlet portions 3b, 23c, 39...Slit portions 5.15...Short fiber composite rubber body 24.29.35...Molded product Fig. 9 Fig. 2 3b Figure 5 Figure 10 Figure 15 Figure 16 (mm) Figure 17 L2 (mm)

Claims (2)

[Claims] (1) By injecting short fiber-mixed rubber into the mold cavity through the rubber inlet, a short fiber composite rubber product with the maximum fiber orientation in the direction corresponding to the height of the rubber inlet can be produced. The rubber inlet has an elongated slit shape, and the height thereof is 1/1/2 of the height of a cavity surface with which the rubber inlet communicates.
2 or less and 2 mm or less. A method for producing a short fiber composite rubber product. (2) A method of manufacturing a short fiber composite rubber product having the maximum fiber orientation rate in the direction corresponding to the direction of expansion of the inlet by injecting short fiber-mixed rubber into the cavity of a molding die through the rubber inlet. and the ratio of the outlet width to the minimum width of the rubber inlet is 2 or more, the ratio of the height of the outlet part to the height of the minimum width part is 2 or less, and the ratio of the area of the exit part to the area of the minimum width part is 2. The method for producing a short fiber composite rubber product as described above, characterized in that the end face of the exit part of the rubber inlet is aligned with one molding surface of the cavity of the molding die.