JP2002165612A - Toe box of safety shoe and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently produce a toe box of safety shoe with excellent mechanical strength against pressure, impact, etc. SOLUTION: The box toe of safety shoe consists of the main body of the box toe molded of a component B comprising at least thermoplastic resin and a fiber reinforcing thermoplastic resin surface material A of 30-1300 μm in thickness comprising reinforcing fibers in one direction or multi-directions and thermoplastic resin. The surface material A is integrated and disposed on the inner surface of the main body of the box toe of safety shoe, and a method of manufacturing the box toe is also provided here.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety shoe tip and a method of manufacturing the same, and more particularly, to provide a lightweight and high-strength safety shoe tip with high production efficiency.

[0002]

2. Description of the Related Art Conventionally, as a method of manufacturing a core for safety shoes, a fiber-reinforced thermoplastic resin such as a tape is randomly dispersed, heated and pressed to obtain a fiber-reinforced thermoplastic resin sheet. Japanese Patent Application Laid-Open No. 9-109310 discloses a method for press-molding the sheet to produce a safety shoe tip. Further, a composite material comprising a reinforced fiber thermoplastic resin layer reinforced with a woven or knitted fabric or a unidirectional reinforced fiber and a reinforced fiber thermoplastic resin layer reinforced with a random reinforcing fiber is formed. Japanese Patent Laid-Open No. 9-30 discloses a method for producing a tip for safety shoes by heating and pressing a material.
No. 9171.

According to the method disclosed in the above publication, however, although the mechanical strength of the obtained safety shoe tip is improved, it takes time and effort to produce the sheet, and the sheet is cut out and formed. The sheets need to be laminated in several layers, and the laminate needs to be heated and pressed, which is extremely labor-intensive and inferior in production efficiency.

[0004] On the other hand, another method of manufacturing a tip core for safety shoes is disclosed in JP-A-9-238708 by injecting a thermoplastic resin into a mold from a specific injection port of an injection mold. A method has been disclosed in which the orientation of the resin flow is eliminated, the orientation of the reinforcing fibers is lost even when the reinforcing fibers are contained in the thermoplastic resin, and as a result, the pressure resistance and impact resistance of the leading core are improved. I have.

[0005]

However, in the manufacturing method described in the above-mentioned Japanese Patent Application Laid-Open No. 9-238708, although the productivity is good, the mechanical properties of the leading core such as pressure resistance and impact resistance are still high. The strength was poor. Therefore, an object of the present invention is to provide a safety shoe tip having excellent mechanical strength such as pressure resistance and impact resistance with high productivity.

[0006]

According to the present invention, there is provided a safety shoe leading core body (hereinafter, simply referred to as "leading core body") formed from a composition (B) containing at least a thermoplastic resin. Or the thickness 3 of the multidirectional reinforcing fiber and the thermoplastic resin
0-1300 μm fiber reinforced thermoplastic resin facing (A)
(Hereinafter simply referred to as “face material (A)”), wherein the face material (A) is integrated so as to be disposed on the inner surface of the front core body. A core (hereinafter, simply referred to as “tip core”);

Further, according to the present invention, after the face material (A) is placed in a core molding die, a composition (B) containing at least a thermoplastic resin is subjected to injection molding, injection melt compression molding or The present invention provides a method for manufacturing a leading core, wherein the leading die is filled into the molding die by extrusion melt compression molding, and the face material (A) is integrated so as to be disposed on an inner surface of the leading core body. .

According to the present invention, when the face material (A) is placed in the mold for forming the core, the position of the face material (A) is set inside the body of the core to be molded. The mechanical strength is improved. In the present invention, productivity is excellent because a molding method such as injection molding is used for molding of the core. Furthermore, the tip according to the present invention is excellent in lightness and production cost,
In addition, it is possible to adapt to a core that passes L class, S class and H class defined in JIS T 8101.

[0009]

Next, the present invention will be described in more detail with reference to preferred embodiments. The details of the leading core of the present invention will be described in detail together with the manufacturing method thereof. The face material (A) used in the present invention is made of a unidirectional or multidirectional reinforcing fiber and a thermoplastic resin. For example, one or more sheets of the reinforcing fiber and the thermoplastic resin are used. Of the sheet itself or anything obtained by them.

The reinforcing fibers used for the face material (A) include glass fibers and carbon fibers, and the use of glass fibers is preferred in terms of mechanical strength and cost. The reinforcing fibers generally have an average monofilament diameter of 6 to 23 μm, preferably 10 to 17 μm. When the average diameter of the monofilament is less than 6 μm, a glass long fiber reinforced thermoplastic resin base material (face material A)
However, it is not preferable because the cost increases. On the other hand, when the average diameter of the monofilament exceeds 23 μm, the thickness of the face material (A) increases, and the moldability of the face material in a mold is poor, which is not preferable. Further, the reinforcing fibers are:
The number of the filaments is preferably from 200 to 4000, depending on the arrangement of the fibers used.

The unidirectional reinforcing fibers include those in which the above fibers are aligned in one direction. Among them, those in which strands in a bundle of filaments are arranged in one direction, and those in which filaments are opened. One that is delicate and aligned in one direction. Among these, in order to make the face material (A) thin and to eliminate the variation in the strength of the obtained core, it is preferable that the filaments are arranged in an opened state.

The multidirectional reinforcing fibers can be obtained by laminating the unidirectional reinforcing fibers in different directions or forming them into a woven or knitted form and then compounding with a resin to form a sheet. Another method of making the reinforcing fibers multidirectional is to form a sheet by compounding a thermoplastic resin with the unidirectional or multidirectional reinforcing fibers obtained as described above, and then the fiber orientation of this sheet becomes different. By laminating a plurality of such layers, it is possible to obtain substantially multidirectional reinforcing fibers. Among these, from the viewpoint of moldability and mechanical strength, it is particularly preferable to use the face material (A) obtained by laminating a plurality of sheets of unidirectional reinforcing fibers and thermoplastic resin in multiple directions.

The thermoplastic resin used for the face material (A) is not particularly limited, and various commercially available resins can be used. For example, polyolefin-based resins, polyamide-based resins, polyester-based resins, polycarbonate resins, polyphenylene sulfide resins, polystyrene and the like can be mentioned. Among them, from the viewpoints of impregnation, cost and physical properties, polyolefin resins, polyamide resins,
Polyester-based resins are preferred in the present invention. As the polyolefin resin, for example, polypropylene,
Polyethylene and the like; as the polyamide resin, for example, nylon 6, nylon 66, nylon 12, MXD
Nylon and the like; As the polyester resin, for example,
Examples thereof include polyethylene terephthalate and polybutylene terephthalate, and use of these resins is particularly preferable in the present invention. These resins may be mixed with additives such as a coloring agent, a denaturing agent, an antioxidant, and a UV-resistant agent.

The thickness of the face material (A) used in the present invention is 3
It is important that the thickness is 0 to 1300 μm,
It is preferably from 0 to 1000 μm. The face material (A) used in the present invention has a weight per unit area of 50.
Preferably it is で 2000 g / m ² . The thickness is less than 30 μm or the weight per unit area is 50 g
If it is less than / m ² , it is difficult to handle the face material (A), and a sufficient reinforcing effect cannot be obtained in the obtained core. On the other hand, if the thickness exceeds 1300 μm or the weight per unit area exceeds 2000 g / m ² , the die for forming the front core is deeply drawn, so that the die of the face material (A) has a convex shape. Insufficient shaping of the portion corresponding to the above, causes wrinkles and blisters to occur in the obtained core body, and the resulting core does not have sufficient mechanical strength. In the present invention, the thickness of the face material (A) includes a laminate of a plurality of sheets or a case where a resin film is laminated as necessary, and refers to the entire thickness of these.

The method of preparing the face material (A) is not particularly limited, but includes a method of coating a reinforcing fiber by melting a thermoplastic resin, a method of combining a powder resin with a reinforcing fiber, and then melting the resin by heating. A method of coating the reinforcing fibers, after laminating the resin film on the reinforcing fibers, selecting or combining a method of impregnating or coating the resin in the reinforcing fibers by heating or the like, forming a sheet, using this alone and the face material Alternatively, it is also possible to obtain a face material (A) by laminating a plurality of sheets obtained in this way. Among these, when preparing the sheet, it is preferable to use the resin film, and it is preferable to use a thermoplastic resin film having a thickness of 10 to 100 μm. This allows
Preparation of the sheet (A) becomes easy. It is also preferable that a film is further laminated on the obtained sheet (A) to form a face material. Accordingly, when the face material (A) is formed by suction or the like at the time of molding, sufficient shaping can be performed because the face material (A) has no holes. In this case, the thickness of the film is preferably from 20 to 200 μm from the viewpoint of handleability and shapeability.

In the present invention, the composition (B) to be filled in a mold for molding the core body by injection molding, injection melt compression molding or extrusion melt compression molding contains at least heat in the composition. It is necessary that a plastic resin is contained. As the thermoplastic resin, the face material (A)
The same or similar thermoplastic resins are preferably employed. In addition, face material (A)
It is preferable that the heat distortion temperature of the thermoplastic resin used for the composition is higher than the heat deformation temperature of the thermoplastic resin used for the composition (B). Thereby, both can be integrated while suppressing deformation of the face material (A) during molding.

Further, the composition (B) may contain additives such as reinforcing fibers, fillers and lightweight aggregates in addition to the thermoplastic resin. Examples of the reinforcing fibers include glass fibers and carbon fibers, and examples of the filler include mica and talc. Examples of the lightweight aggregate include glass balloons, silica balloons, and pearlite. The additive is charged separately into the molding machine as a raw material with the thermoplastic resin, and then kneaded by a molding machine and filled in a mold. After preparing the base material described above, a method of filling the base material alone or by adding a thermoplastic resin into a mold is exemplified. Among them, a method in which a base material is prepared in advance and put into a molding machine is preferably adopted from the viewpoint of handleability, moldability and quality stability.

As the base material, a pellet of a fiber reinforced thermoplastic resin base material (FRTP) in which chopped strands and a thermoplastic resin are kneaded, or a continuous reinforcing fiber is impregnated with a thermoplastic resin and cut. Long fiber reinforced thermoplastic resin base material (L-FRTP) such as pellets, wire rods, and tapes obtained by the above method. Of these, the use of L-FRTP, in which the fibers are long, increases the remaining fiber length in the core body even after molding, and as a result, improves the mechanical strength of the core body, and is thus relatively lighter. Thus, it is possible to obtain a converted core body. Further, since the L-FRTP can increase the content of fibers, a high-strength core can be obtained, and the cost can be reduced by diluting the L-FRTP with a thermoplastic resin during molding. Is also advantageous. As the form of the substrate, a pellet or a wire is preferably employed from the viewpoint of handleability.

The reinforcing fibers used in the L-FRTP include glass fibers and carbon fibers. The average diameter of the monofilament is usually 6 to 23 μm,
It is preferably from 0 to 17 μm. If the average diameter of the monofilament is less than 6 μm, the cost of the glass long fiber reinforced thermoplastic resin base material (composition B) increases, which is not preferable. On the other hand, when the average diameter of the monofilament exceeds 23 μm, the mechanical strength is undesirably reduced. Further, the number of the reinforcing fibers is preferably 200 to 12,000, more preferably 600 to 9600, depending on the arrangement of the fibers to be used.

The L-FRTP has a reinforcing fiber content of 4
It is preferably from 0 to 80% by weight, more preferably from 50 to 70% by weight. When the reinforcing fiber content is less than 40% by weight, the reinforcing effect is small. On the other hand, 80% by weight
Exceeding the above range is undesirable because the thermoplastic resin as a matrix component to be used decreases, and the mechanical strength and the like decrease. Further, the length of the L-FRTP is preferably from 3 to 30 mm, and particularly preferably from 6 to 20 mm. If it is less than 3 mm, a sufficient reinforcing effect cannot be obtained, and if it exceeds 30 mm, clogging occurs in a hopper portion of a molding machine, and workability is undesirably reduced.

In the method for manufacturing a core according to the present invention, after the face material (A) is placed in a mold for core molding, the composition (B) is subjected to injection molding, injection melt compression molding or extrusion. The mold is filled by melt compression molding, and the face material (A) is integrated so that the face material (A) is arranged on the inner surface of the front core.

Surface material (A) to be arranged in a core molding die
Is preferably a surface material cut out into a specific shape in advance, or a surface material cut out into a specific shape in advance into the shape of a mold convex portion. Also, after arranging continuous face materials in a mold, face materials obtained by cutting into a specific shape are mentioned, and further forming a continuous face material into a convex shape,
It is preferable that the face material be obtained by cutting out a specific shape substantially before or after the mold clamping. The preferred shape in the specific shape is an inner shape of the obtained core body, that is, a shape obtained by expanding a convex mold of a mold corresponding to the inner side, and more preferably the same or more than the developed shape. Is also large overall.

The method of arranging the face material (A) in a mold is easy to shape into a core, and in order to sufficiently integrate with the composition (B), the face material (A) is used. Is preferably heated. Before further filling the composition (B),
It is preferable to hold the face material (A) so as not to lose its shape. When filling the composition (B), the pressure is applied to shape the face material (A) into a convex shape of a mold. While letting
A method of filling the composition (B) may be mentioned, but the face material (A) is maintained while maintaining the shape of the face material (A) without being deformed.
In order to quickly arrange in a mold, it is more preferable to shape the face material (A) in advance in a shape that matches the convex shape of the mold.

As a preferred method of shaping the face material (A) into a mold shape, the face side of the mold (A) is suctioned to the surface of the convex side while the pressure on the convex side of the mold is reduced from the inside. Material (A)
In a convex shape, or a method in which the face material (A) is pressed by a pressurized bag method or manually and shaped according to the convex shape of the mold. They may be used alone or in combination.

The portion where the face material (A) is arranged inside the tip core body can be arranged at an arbitrary position inside the tip core body, or can be arranged wholly or partially. is there. Preferably, the face material (A) is arranged on the entire inside of the front core. Further, it is preferable to use the face material (A) formed by laminating a plurality of sheets because the mechanical strength of the leading core can be improved. Further, when the face material (A) is partially arranged on the front core body, it is particularly preferable to dispose the face material (A) at the position of the instep tip inside the front core body because the impact strength of the front core is improved.

For the molding of the composition (B), a method of filling the composition (B) into a core molding die of an injection molding machine, an injection melt compression molding machine or an extrusion melt compression molding machine is used. Is important, so that the productivity of the leading core can be improved. The molding method is not particularly limited, but a normal molding method according to the molding method is employed. Of these, it is particularly preferable to use injection molding because of its excellent production efficiency.

The core of the present invention obtained as described above is:
The face material (A) is disposed inside the molded body, and is integrated with the composition (B) constituting the leading core body. Further, by disposing the face material (A) inside the front core, the mechanical strength of the front core is improved, and in particular, a front core with improved impact strength and pressure resistance required for the front core is obtained. In addition, the safety shoes can be reduced in weight in combination with the improvement in the mechanical strength.

[0028]

Next, the present invention will be described more specifically with reference to examples and comparative examples. Example 1 First, a sheet is created as follows. Sheet thickness 300 μm Reinforced fiber Glass fiber (unidirectional reinforcement) Thermoplastic resin Polypropylene Glass fiber content 70% by weight Two of the above sheets are laminated so that their fiber directions are orthogonal to each other, and heated and compressed at 200 ° C. and then cooled. (A-1) was obtained. The thickness of this face material is 600 μm, and the unit weight is 10
00 g / m ² .

Next, the composition of the composition (B) is shown. [Composition (B)] Pellet length 6 mm Pellet diameter φ2.2 mm Reinforcement fiber Glass fiber Thermoplastic resin Polypropylene Glass fiber content 70% by weight The above L-FRTP base material is used as composition (B).

As shown in FIG. 1, the face material (A-1) is set in a mold of an injection molding machine, and continuously,
1) was unreeled, and the face material was placed in the mold. Face material (A
After heating with -1) by a heater, vacuum molding is performed by sucking the convex mold of the mold from the inside so as to follow the convex mold of the leading core and reducing the pressure. The state at this time is shown in FIG.

Subsequently, the composition (B) was mixed with polypropylene pellets (MI = 30 / homopolymer) at a weight ratio of 5:
Dry blending was performed at a ratio of 2. The composition (B-
1). The glass fiber content of the diluted resin (B-1) was 50% by weight. Then, the mold is closed and the above (B
-1) was injected and filled in a mold, and after cooling, the mold was opened to obtain a core of the present invention. When the mold is closed, the surrounding surface material (A-1)
Was cut off. That is, there is no deburring step. The form of the compact at this time is shown in FIG. As a result, the face material (A-1) was integrated with the inner face of the molded body without wrinkles. This tip was subjected to an S class test defined in JIS T 8101, and the impact resistance and pressure resistance were measured. Table 1 shows the results.

Example 2 A sheet having the same structure as that of Example 1 was prepared except that the thickness of the face material (A) was 450 μm.
Two sheets were prepared and each was set on an injection molding machine base. At this time, the two sheets are 0/90 on the mold.
The sheet was placed so as to be orthogonal at an angle of ° and the sheet actually placed in the mold was used as a face material (A-2). The surface material at this time (A-
The weight per unit area of 2) was 1500 g / m ² . As the composition of the composition B, the above (B) was used alone.

Next, each of the sheets is set in a mold, heated by a heater, and then pressed by an airbag into which heated air is injected so as to be along the convex-shaped surface of the mold for forming the core. At the same time, the convex portion of the mold is sucked from the inside and the pressure is reduced to perform vacuum forming. The state at this time is shown in FIG. Thereafter, the mold was closed, the composition (B) was injected and filled into the mold, and after cooling, the mold was opened to obtain a core of the present invention. As a result, the face material (A-2) was integrated with the inner surface of the molded body without wrinkles. This tip is JIS T810
An H class test specified in 1 was performed to measure impact resistance and pressure resistance. Table 1 shows the results.

Example 3 As the structure of the face material (A), only the thickness of the sheet of Example 1 was changed to 150 μm, and the other conditions were the same. Two sheets of this sheet were laminated so that the fiber directions were orthogonal to each other, and heated and pressed at 200 ° C. and cooled to obtain a laminated face material. This is referred to as a face material (A-3). This face material (A-3)
Has a thickness of 300 μm and a unit weight of 500 g / m ² .

As the composition of the composition (B), a polypropylene pellet (homopolymer) containing no glass fiber and having MI = 30 was used. This was designated as composition (B-2). Using the face material (A-3) and the composition (B-2),
Molding was performed under the same conditions as in Example 1 to obtain a core of the present invention. This tip was subjected to an L class test specified in JIS T 8101, and the impact resistance and pressure resistance were measured. Table 1 shows the results.

Example 4 As a structure of the face material (A), a glass fiber was used as a satin woven fabric.
A sheet having a glass fiber content of 70% by weight and a thickness of 500 μm was obtained in combination with polypropylene, and one sheet was prepared as a face material. This is designated as a face material (A-4). The composition (B) was prepared under the same conditions as in Example 1 except that the glass fiber content was 60% by weight. This was designated as composition (B-3). The above surface material (A
Using the composition (B-3) and the composition (B-3), molding was performed under the same conditions as in Example 1 to obtain a core of the present invention. This tip is JI
An S class test specified in ST 8101 was performed to measure impact resistance and pressure resistance. Table 1 shows the results.

COMPARATIVE EXAMPLE 1 The front core of the comparative example without the face material (A) was formed under the same conditions as in Example 1 using only the composition (B-1) without using the face material (A). I got This tip was subjected to an S-class test defined in JIS T8101, and impact resistance and pressure resistance were measured. Table 1 shows the results.

Comparative Example 2 A sheet was prepared under the same conditions as in Example 2 except that the thickness of the sheet of Example 2 was changed to 700 μm. This is designated as a face material (A-5). Other than this, Example 2
Molded under the same conditions as The thickness of this face material (A-5) is 1
At 400 μm, the unit weight is 2350 g / m ² . As a result of the above, the face material (A-5) was wrinkled in the molded body, and a leading core main body having a shape along the inside of the leading core could not be obtained.

Comparative Example 3 First, the following sheet is prepared. Sheet thickness 5.7mm Reinforced fiber Glass fiber Fiber length 35mm (non-directional) Thermoplastic resin Polypropylene Glass fiber content 75% by weight Sheet size 90 × 50mm

The same mold as the core molding die used in Example 1 was used.
Prepare a press die for IZ. 200 ° C
Into a far infrared heating furnace heated for 5 minutes. This solution
A press machine in which the above-mentioned mold is set
500kg / cm ^TwoMold for 30 seconds under pressure
I do. As a result, the sheet was formed into a core. Ba
After removal, this tip is specified in JIS T8101.
Perform S-class tests to determine impact resistance and pressure resistance.
Specified. Table 1 shows the results.

Test Example Regarding the cores of the above Examples and Comparative Examples, JIS T 8
101, an impact resistance test and a pressure resistance test were performed. In the impact resistance test, H class 100 (J), S class 70
(J) and L-class 30 (J) impact energy,
H class 15 (KN), S class 10 (KN)
And a compression force of L class 4.5 (KN) was applied to measure the gap between the insole and the front core, and measured 15 mm or more (foot length 29 cm)
), The test was passed. However, when a crack that caused light to pass through on the test axis of the leading core occurred, it was rejected.

[0042]

[0043]

According to the present invention as described above, it is possible to provide a safety shoe tip having excellent mechanical strength such as pressure resistance and impact resistance with high productivity.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a method of the present invention.

FIG. 2 illustrates a method of the present invention.

FIG. 3 illustrates a method of the present invention.

Claims (8)

[Claims] 1. A safety shoe tip core body formed from a composition (B) containing at least a thermoplastic resin, and a thickness of 30 to 1 of a unidirectional or multidirectional reinforcing fiber and a thermoplastic resin.
A safety member comprising a fiber-reinforced thermoplastic resin surface material (A) having a thickness of 300 μm, wherein the surface material (A) is integrated so as to be disposed on the inner surface of the front core body for safety shoes. Tip for shoes. 2. A fiber-reinforced thermoplastic resin face material (A) having a thickness of 30 to 1300 μm of a unidirectional or multidirectional reinforcing fiber and a thermoplastic resin is disposed in a mold for forming a core for safety shoes. (B) containing at least a thermoplastic resin
Is filled into the molding die by injection molding, injection melt compression molding or extrusion melt compression molding, and integrated so that the face material (A) is disposed on the inner surface of the front core body for safety shoes. A method for producing a tip core for safety shoes, characterized in that: 3. The method according to claim ² , wherein the weight per unit area of the face material (A) is 50 to 2000 g / m ² . 4. A sheet made of a unidirectional or multidirectional reinforcing fiber and a thermoplastic resin having a thickness of 20 to 40.
The method according to claim 2 or 3, wherein the face material is obtained by laminating a thermoplastic resin film having a thickness of 200 µm. 5. The composition (B) is a long reinforcing fiber thermoplastic resin base material (L-FRTP), wherein the L-FRTP
The method according to any one of claims 2 to 4, wherein the reinforcing fiber content is 20 to 80% by weight, and the base material length is 3 to 30 mm. 6. The heat deformation temperature of the thermoplastic resin used for the face material (A) is higher than the heat deformation temperature of the thermoplastic resin used for the composition (B). 3. The method for producing a tip core for a safety shoe according to claim 1. 7. The surface material (A) according to claim 2, wherein the surface material (A) is formed into a shape similar to the convex surface of a metal mold for forming a core for safety shoes and arranged in the metal mold. A method for producing a tip for a safety shoe according to the above item. 8. The face material (A) is shaped and arranged in a mold for forming a leading core for safety shoes by suction (decompression) or pressing to have a shape similar to a convex shape of the mold. Item 8. The method for producing a tip for safety shoes according to any one of Items 2 to 7.