JP2006130718A - Mold for synthetic resin in-mold foam molding and synthetic resin in-mold foamed molded product molded using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold capable of easily imparting a sound absorbing capacity without modifying prefoamed particles or requiring the post processing of a molded product, in a manufacturing method of a thermoplastic foamed resin molded product molded by in-mold foam molding. <P>SOLUTION: In the mold constituted for synthetic resin in-mold foam molding so that the molding space, which is demarcated by one set of molds composed of a core mold and a cavity mold, is filled with prefoamed particles and the prefoamed particles are heated by a heating medium to be foamed and welded to obtain a foamed molded product, a plurality of plate-like members for providing grooves to the molded product are arranged to at least one of one set of the molds. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a mold for producing a foamed molded product in a synthetic resin mold.

  It is widely known that a plurality of through holes or bottomed holes are provided in an inorganic material such as metal, gypsum board, and ceramic to exhibit a sound absorbing effect in a specific frequency range. Several examples in which this is applied to a resin foam are disclosed.

  As a first example, a method is disclosed in which a sound absorbing hole is provided by piercing a molded product with a sharp object having a needle, pin, spike, or nail shape (see Patent Document 1). However, in this method, there is a problem that the product is deformed or the product is crushed depending on the needle pitch or diameter, or the sound absorbing hole is blocked due to the elastic recovery of the foamed product. In the method using a drill, a laser, a high-pressure fluid, an air gun, etc., it has been difficult to make a large number of holes because complicated drilling is required or an expensive device is required.

  As a second example, there is a method by punching in post-processing. An EPDM (ethylene / propylene / diene terpolymer) and soft urethane formed by punching and forming through-holes having a diameter of 10 mm at a pitch of 20 mm is disclosed (Patent Document 2). However, when the technique described in Patent Document 2 is applied to, for example, a structure having only closed cells, it is difficult to change the pitch, particularly to a small pitch. In particular, since more holes are required to increase sound absorption efficiency, it is obvious that punching becomes difficult as the thickness of the molded product increases, and the pitch is narrowed more than the above. In some cases, the product is crushed or deformed, and it is difficult to provide sound absorbing holes at a desired pitch.

  As a third example, there is disclosed a method of heating a needle-like object, a rod-like object or the like in post-processing to melt a resin to form a sound absorbing hole (Patent Document 3). When such a method is used, a very large number of needles are required to obtain a good sound absorption effect, so that the processing apparatus becomes complicated and a large number of needles are heated uniformly. It was difficult to form a plurality of good holes at the same time. Furthermore, from a cost standpoint, it goes without saying that processing costs increase because post-processing is added to the manufacturing process.

As a fourth example, a method is disclosed in which a sound absorbing hole is formed at the time of molding by attaching a member having needle-like or rod-like projections to a mold for in-mold foam molding (Patent Document 3, Patent) Reference 4). Providing such a complicated member in the mold tends to increase the mold cost, as a matter of course, because the mold structure becomes very complicated. In addition, from the viewpoint of the sound absorption effect, it is necessary to arrange a large number of needle-like projections at a narrower pitch. In such a case, it is difficult to form pre-expanded particles between needle-like projections with a narrow pitch than the problem of filling with pre-expanded particles, and it is difficult to obtain good products. Many problems of product deformation have occurred due to an increase in the mold release resistance of the needle-like part at the time of mold release.
Japanese translation of PCT publication No. 6-507129 JP 2000-206976 A JP 2003-335893 A JP 2003-340858 A

  An object of the present invention is to provide a sound-absorbing performance easily without requiring modification of pre-foamed particles or post-processing to a molded body in a method for producing a thermoplastic foamed resin molded body molded by in-mold foam molding. It is to provide a mold that can be used.

  As a result of intensive studies to solve the above problems, the present inventors have arranged a plate-like member on at least one mold of a set of molding molds including a core mold and a cavity mold. By molding pre-expanded particles made of thermoplastic resin using a mold, a groove having a predetermined shape can be formed in the molded body, and sound absorbing performance is imparted by the groove formed on the surface of the molded body. Of course, the present inventors have found that the sound absorption frequency range can be designed and completed the present invention.

  That is, according to the first aspect of the present invention, pre-expanded particles are filled in a molding space defined by a set of molding dies including a core mold and a cavity mold, and the pre-expanded particles are heated by a heating medium. In a molding die for obtaining a foamed molded article by foaming and fusing, a plurality of plate-like members for providing grooves in the molded article are arranged in at least one mold of a set of molds. The present invention relates to a mold for foam molding in a synthetic resin mold.

As a preferred embodiment,
(1) providing the plate-like member in a first mold having an eject pin;
(2) A plate-like member in which a plate-like member is arranged in both the core die and the cavity die, and the surface area of the plate-like member arranged in the first die having the eject pin is arranged in the other die. Set larger than the surface area of the member,
(3) A plate-shaped member is arranged on both the core mold and the cavity mold, and the taper angle of the plate-shaped member disposed on the first mold having the eject pin is disposed on the other mold. That it was set below the taper angle of the plate-like member,
(4) The thickness of the plate member is 1 mm or more and 10 mm or less,
(5) The arrangement interval of the plate-like members is set to 3 mm or more and 50 mm or less,
(6) setting at least two heights of the plate-like member;
(7) Setting at least two or more thicknesses of the plate-like member;
(8) Arranging the plate members in parallel, lattice, radial, concentric circles,
(9) The ratio of the total cross-sectional area of the plate-shaped member of the mold to the surface area of the foam in one mold where the plate-shaped member is disposed is 1.5% or more and 15% or less,
The above-mentioned synthetic resin mold for foam molding is characterized by the above.

  A second aspect of the present invention relates to a synthetic resin in-mold foam-molded product manufactured using the above-mentioned synthetic resin mold in-mold foam molding, and as a preferred embodiment, the synthetic resin in-mold foam-molded product has a plurality of It is related with the said synthetic resin in-mold foam-molding body whose said groove | channel is bottomed and / or penetrated.

  3rd of this invention is related with the interior material for vehicles, a floor material, and a wall material which consist of the said synthetic resin type | mold foaming molding.

  By using the mold for foam molding in the synthetic resin mold of the present invention, the current spare is used without any special modification of raw materials to give sound absorption performance, and without post-processing that increases the cost. By using the expanded particles and the manufacturing process, an in-mold expanded molded article having a sound absorbing performance can be easily obtained. Furthermore, it is possible to reduce the cost of remodeling the mold and improve the filling property of the raw material, which cannot be achieved by the conventional method of arranging the needle-shaped member in the mold. Further, by changing the shape of the groove of the molded body, it is possible to change to a desired sound absorption rate and sound absorption frequency, and to obtain a good sound absorption effect.

  The synthetic resin in-mold foam molded body obtained by the mold of the present invention is a foam molded body having a high degree of freedom in shape design and sufficient high dimensional accuracy and compressive strength. Therefore, it is represented by floor spacers and various pads. It can be suitably used for interior materials for vehicles, floor materials for buildings such as houses, and wall materials.

  The present invention will be described in detail below.

  The structure of the metal mold | die of this invention and the shaping | molding procedure of a synthetic resin in-mold foaming molding are demonstrated using FIG.

  The mold of the present invention has a molding space 3 defined by a cavity mold 1 and a core mold 2, and a plurality of plate-like members 4 for imparting sound absorbing performance are arranged in the molding space. A plurality of the plate-like members 4 are arranged in at least one of the molds of the cavity mold 1 and the core mold 2, and are arranged so that a groove is provided on the side of the molded body that requires sound absorption performance. The In the present invention, a mold provided with an eject pin is sometimes referred to as a first mold, but generally, the eject pin 5 is often disposed in the cavity mold 1 and molding from the mold is performed. From the viewpoint of stable release of the body, it is preferable to design so that the surface requiring sound absorbing performance is disposed in the first mold in which the eject pin 5 is disposed. With such an arrangement, it is possible to increase the mold release resistance of the molded body on the eject pin side, and it is easy to leave the molded body on the mold side where the eject pin 5 is disposed. If the plate-like member 4 cannot be disposed on the first mold side due to the required product shape, the mold structure may be configured so that the vapor chamber 7 can be evacuated, although not shown, or the vapor chamber 8. It is good also as a metal mold | die structure which presses a product against the metal mold | die side by the side of an eject pin by pressurizing air. Further, a suction and pressure mold structure may be used in combination. By adopting such a mold structure, the molded body can be left on the first mold side where the eject pin is disposed, and the molded body can be easily released from the mold.

  The plate-like member 4 may be disposed on both the cavity mold 1 and the core mold 2. By setting it as such a structure, the sound absorption performance to both surfaces of a molded object can be provided. However, in such a configuration, it is preferable to devise a method of leaving the molded body on the side of the first mold having the eject pin 5 at the time of mold release. For example, the molded body mold release of the first mold having the eject pin 5 is performed. There is a method of increasing the resistance. More specifically, there is a method in which the shape or installation interval of the plate-like members 4 arranged in the cavity mold 1 and the core mold 2 is different between the two molds. Specifically, the plate-shaped member arrangement interval on the first mold side having the eject pin 5 is narrow, and the plate-shaped member arrangement on the other mold side is as much as possible within a range where a predetermined sound absorption coefficient can be obtained. The surface area of the plate-like member 4 of the first mold provided with the eject pin is improved by adjusting the thickness of the plate-like member 4 to improve the mold release resistance of the first die on the eject pin side. Is set larger than the surface area of the plate member 4 of the other mold, and the taper angle θ (FIG. 2) of the plate member on the first mold side provided with the eject pin 5 is set to the plate shape of the other mold. Examples thereof include a method in which the plate member 4 is subjected to surface treatment and the sliding resistance with the molded body is changed by changing the surface roughness. Furthermore, these adjustments and vacuum suction or air pressurization may be combined. However, since the height α of the plate member 4 (FIG. 2, the groove depth on the surface of the molded body) is closely related to the sound absorption frequency, it is difficult to adjust the mold release resistance by the height α of the plate member 4. There is. Therefore, the surface area of the plate member 4 of the first mold having the eject pin 5 is set larger than the surface area of the plate member 4 of the other mold, or the plate of the first mold having the eject pin 5. It is preferable to use a method in which the taper angle θ of the plate-like member 4 is set to be equal to or smaller than the taper angle of the plate-like member 4 of the other mold because it can be set without depending on the sound absorption frequency.

  Next, the plate-like member 4 will be described. Here, the height α, the width β, and the thickness γ of the plate-like member 4 in the present invention indicate the dimensions shown in FIG. In order to develop sound absorption performance, the thickness γ of the plate-like member 4 is preferably 1 mm or more and 10 mm or less. More preferably, they are 2 mm or more and 7 mm or less. If the thickness γ of the plate-like member 4 is less than 1 mm, the molded body shrinks after molding, and the groove on the surface of the molded body is blocked, or an effective opening width for providing sound absorption cannot be secured, and a desired sound absorbing performance is obtained. It may not be obtained. On the other hand, if the thickness γ of the plate-like member 4 exceeds 10 mm, the resonance performance of air in the groove imparted to the molded body is lowered, so that the sound absorption rate may be lowered. In addition, by setting at least two thicknesses of the plate-like member 4, it is possible to increase the arrangement variation of the plate-like member 4 and further change the number of the plate-like members 4, so that a high sound absorption coefficient is obtained. It is preferable because sound absorbing performance can be easily imparted to molded products having various shapes in the maintained state.

  The width β of the plate-like member 4 is not particularly limited. However, when the width β of the plate-like member 4 is set to be long, the rigidity of the foam is lowered, so that there is a concern about the occurrence of twisting or bending. Alternatively, in order to maintain the rigidity of the plate-like member 4, the upper limit of the width β of the plate-like member 4 is preferably about 100 mm, and more preferably 50 mm or less. Moreover, in order to reduce the number of the plate-like members 4 as much as possible and maintain a high sound absorption coefficient from the viewpoint of mold cost and moldability, the lower limit is preferably 15 mm, and more preferably 30 mm. The height α of the plate-like member 4 is not particularly limited, and a groove penetrating the molded body may be given, or a mold is formed as shown in FIG. 1 to give a bottomed groove to the molded body. Or a combination of both. From the viewpoint of ease of mold manufacture, it is preferable that the height be such that a bottomed groove can be provided. In addition, it is preferable to set the height of the plate-like member 4 to two or more because it can be designed to absorb sound of different frequencies.

  The shape of the plate-like member 4 may be a simple plate-like shape such as a rectangle as shown in FIG. 3 (a), but should have a shape with irregularities in the height direction as shown in (b). Therefore, it is preferable because the filling property and the strength of the molded body can be improved. As shown in (c), one plate-like member 4 may be configured to have several heights, or a part of the cross-sectional shape may be changed. By using such a plate-like member 4, several types of groove depths and groove shapes can be formed even with a single plate-like member 4, so that various sound absorption frequency designs are facilitated. Furthermore, the shape and size of the cross section at each position in the height direction do not necessarily have to be the same, and the cross-sectional shape gradually becomes thinner or thinner gradually as it approaches the center of the molded body. Arbitrary shapes such as those that change can be adopted. The height, pitch, and shape of the plate-like member 4 can be appropriately selected and combined as long as they are within a shape range that exhibits sound absorption characteristics and a range that satisfies compression characteristics.

  There is no particular limitation on the cross-sectional shape of the plate-like member 4. For example, the cross-sectional shape of the plate-like member 4 may be a straight line shown in FIG. 4, a straight line such as a cross, a letter S, a curve such as a sine wave, a wave, or a circle, And a zigzag line such as a letter shape, a shape represented by a combination of a straight line and these curves.

  The arrangement of the plurality of plate-like members 4 can also be set freely. As the arrangement of the plate-like member 4 having an end on the surface of the molded body, as shown in FIG. 5, parallel, grid-like, zigzag, spiral, radial, and the like can be mentioned, and the shape having no end is circular, Polygonal shapes are listed, and one or more of them can be used. Among them, it is preferable to arrange them in parallel, lattice, radial or concentric circles.

  The arrangement interval of the plurality of plate-like members 4 is not particularly limited as long as the sound absorption groove capable of maintaining a good sound absorption rate can be formed in the foamed molded product, but is usually preferably set to 3 mm or more and 50 mm or less, and the entire sound absorption surface. In order to absorb sound uniformly, it is more preferably set to 5 mm or more and 30 mm or less. It is preferable to set the arrangement interval of the plate-like members 4 within the above range from the viewpoint of molding processing, particularly from the viewpoint of filling pre-expanded particles and releasing the molded foam. Here, the arrangement interval of the plate-like members 4 refers to the interval between the plate-like members 4 and the plate-like members 4 in the thickness direction of the plate-like member 4.

  In addition, the ratio of the total cross-sectional area of the plate-like member 4 of the same mold to the surface area of the molded body in one mold where the plate-like member 4 is arranged is preferably 1.5% or more and 15% or less. More preferably, it is 2% or more and 10% or less. Within this range, both good sound absorption and good compression characteristics can be achieved. The “surface area of the molded product” here refers to the surface area of the molded product when it is assumed that no groove is provided to the molded product, and does not include the area of the groove side wall or the like generated by providing the groove. . The “total cross-sectional area of the plate-like member 4” refers to the total area of the open groove portions provided to the surface of the molded body by the plate-like member 4.

  As shown in FIG. 7, the plate member 4 is attached to the mold by sandwiching the plate member 4 with a pedestal 18 and fixing the pedestal 18 to the mold 1 as shown in FIG. Form (g) for fixing the plate-like member 4 on the mold surface, a through groove through which the plate-like member 4 can pass is provided in the mold 1, and the plate-like member 4 protrudes into the molding space 3 from this portion, and the back of the mold The method (h) of fixing with is not limited to this. From the viewpoint of ease of maintenance of the plate-like member 4, it is possible to replace the plate-like member 4 even when a mold is attached to the molding machine. preferable. From the viewpoint of the strength of attachment of the plate-like member 4, (d) and (h) are preferable because the plate-like member 4 can be more firmly fixed to the mold. From the viewpoint of suppressing the generation of burrs, the structures (d) and (g) are preferable. Also in the structure of (h), it is preferable to provide such a shape because it is possible to suppress the generation of burrs because the surface of the molded body becomes concave by providing projections such as 22 on the mold surface. .

  The material of the plate-like member 4 is not particularly limited as long as it has strength capable of suppressing deformation at the time of molding or mold release. For example, stainless steel, aluminum material, brass, spring steel, titanium alloy, Ceramics and heat resistant resins are preferably used. These plate-like members 4 may be subjected to a surface treatment such as a Teflon (registered trademark) coating treatment or an alumite treatment to improve the slipperiness or to increase the surface strength of the plate-like member 4.

  The pre-expanded particles that can be suitably used in the present invention are preferably made of a thermoplastic resin. Examples of the thermoplastic resin include polymethyl methacrylic resin; polystyrene, poly α-methyl styrene, styrene-polyethylene. Resins, styrene maleic anhydride copolymers, blends or ground copolymers of polyphenylene oxide and polystyrene, styrene resins such as styrene-acrylonitrile copolymers, acrylonitrile-butadiene-styrene resins, styrene-butadiene copolymers, high impact polystyrene; polyvinyl chloride, chloride Vinyl chloride resins such as vinyl-vinyl acetate copolymers, copolymers of ethylene or propylene and vinyl chloride; polyamide resins; polyester resins; polycarbonate resins; Chlorinated resins such as polyethylene and chlorinated polypropylene; polyolefin resins. In view of the physical properties of the molded article, it is preferable to use a polyolefin resin. Polyolefin resins include polypropylene resins such as polypropylene, ethylene-propylene random copolymers, propylene-butene random copolymers, ethylene-propylene-butene terpolymers, low-density polyethylene, linear ultra-low Polyethylene resins such as density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, and ionomer are used alone or in combination. In addition, these polyolefin-based resins are preferably non-crosslinked, but crosslinked resins can also be used. In addition, as a compounding agent, an antioxidant, an ultraviolet absorber, a flame retardant, an antistatic material, a colorant such as a pigment, a plasticizer, a lubricant, a crystallization nucleating agent, an inorganic filler such as talc, calcium carbonate, etc. It may be a thing. In the present invention, the foam molded body made of a synthetic resin may have a closed cell shape or open cell shape, or a mixture of these. Among them, those having a closed cell ratio of 90% or more can be preferably used in the present invention because they can maintain high compressive strength as both an impact energy absorbing material for automobile members and a floor material. Furthermore, from the viewpoints of shock absorption, heat resistance, chemical resistance, and durability, polypropylene or polyethylene is used as a base resin, pre-expanded particles pre-expanded at a predetermined magnification are filled in a mold, and heated steam is used. It is preferable to apply the present invention to a synthetic resin in-mold foam molded product obtained by a method of taking out a molded product after being cooled and solidified after being foamed and fused. Furthermore, the foaming ratio of the foamed molded product is preferably 2 to 100 times, and more preferably 3 to 60 times.

  Next, the molding apparatus will be described.

  The in-mold foam molding apparatus includes a cavity mold 1 and a core mold 2 as a pair of opposed molds, and a flow of air in a molding space 3 defined by closing the cavity mold and the core mold. A filling device 6 for filling the pre-expanded particles on the surface, a decompression means (not shown) for decompressing the molding space, and a compressed air supply means (not shown) for introducing the compressed air into the molding space. And vapor supply means 9 and 10 for heating and foaming the pre-expanded particles filled in the molding space, and an ejector pin 5 for releasing the molded product. The cavity mold 1 and the core mold 2 are respectively attached to housings having frame-shaped frames 11 and 12 and back plates 13 and 14, and vapor chambers 7 and 8 are formed on the back surfaces of the cavity mold 1 and the core mold 2. Has been. The cavity mold 1 and the core mold 2 are formed with vent holes including a core vent 15 and a core vent hole that communicate the molding space 3 with the steam chambers 7 and 8. Each of the steam chambers 7 and 8 is connected to steam supply means 9 and 10 and compressed air supply means via a service valve. Each of the steam chambers 7 and 8 is provided with a unit (not shown) for spraying cooling water onto the back surfaces of the cavity mold 1 and the core mold 2. In FIG. 1, the plurality of plate-like members 4 for forming grooves for imparting sound absorption performance to the cavity mold 1 having the eject pins 5 are formed in a protruding shape in the molding space 3.

  Next, a method for molding a foam molded body using an apparatus including the mold for in-mold foam molding of the present invention will be described. This molding method includes a filling step of filling the molding space 3 with pre-expanded particles, a heating step of heating and foam-fusing the pre-foamed particles filled in the molding space, and a cooling step of cooling the molded foam molded body. And, it is divided roughly into four processes of the mold release process which releases a foaming molding from a metal mold | die.

  In the filling step, the cavity mold 1 and the core mold 2 are closed, and the air supplied into the molding space 3 is discharged from the core vent 15 to the outside of the molding space, while being reserved for the molding space 3 from the filler 6. The expanded particles are supplied on the air flow, and the pre-expanded particles are filled in the molding space. In addition, as the pre-expanded particles, it is possible to use so-called component-containing particles, in which air having a pressure equal to or higher than atmospheric pressure is press-fitted into the particles before molding to give foaming force. As a specific filling method, a cracking filling method, a pressure filling method, a compression filling method, or the like can be adopted. Here, in the cracking filling method, the cavity mold 1 and the core mold 2 are not completely closed at the time of filling. For example, about 10% of the bottom thickness of the foamed molded body is opened and the gap between both molds is opened. The pre-expanded particles are filled while discharging the air used for filling. In the pressure filling method, the inside of the raw material tank (not shown) containing the pre-expanded particles is pressurized by about 0.02 to 0.15 MPa, and the forming space is opened to atmospheric pressure. Using the differential pressure, the pre-expanded particles are conveyed and filled into the molding space. In the compression filling method, the pressure in the raw material tank is increased to about 0.01 to 0.50 MPa, the molding space 3 is pressurized in a state lower than the raw material tank pressure, and the pre-expanded particles are conveyed while maintaining the differential pressure. And filling.

  Next, the heating process will be described. By supplying steam to the steam chambers from the steam supply means 9 and 10 with the drain lines 16 and 17 of the cavity mold 1 and the core mold 2 being opened, the air in the two steam chambers is discharged out of the system. . Next, steam is supplied to one steam chamber and discharged from the other steam chamber, whereby the air in the molding space is discharged and the pre-expanded particles and the mold are preheated. Next, in a state where both drain lines 16 and 17 are closed, steam is supplied to both the steam chambers 7 and 8 to heat and foam the pre-expanded particles.

  In the next cooling step, cooling water is sprayed from a nozzle unit (not shown) toward the cavity mold and the core mold, and the foam molded body in the molding space 3 can be released through the cavity mold 1 and the core mold 2. Cool and solidify to product hardness.

  In the mold release process, the cavity mold 1 and the core mold 2 are opened. In general, a plate-like member 4 is formed on the cavity mold 1 having the eject pin 5, and the separated mold resistance is the core mold. Since it is larger than 2, the foamed molded product remains on the cavity mold side. However, compressed air is supplied from the back side of the core mold 2 so that the foamed molded product can be easily separated from the core mold, or the vapor chamber of the cavity mold 1 is decompressed to the cavity mold 1 side. The mold may be opened while adsorbing the foamed molded product. Thus, since it becomes possible to leave a foaming molding on the cavity type | mold 1 side, the mold release defect of a foaming molding can be prevented effectively. Thus, in a state where the foam molded body remains in the cavity mold 1, the foam molded body is protruded by the eject pin 5 and released from the mold.

  Since the foamed molded product immediately after release contains a lot of moisture, it is dried at room temperature or at high temperature. In particular, when shrinkage is observed immediately after molding, since the groove for absorbing sound is closed, it is preferable that the shape is recovered by high-temperature drying.

  The thickness of the foamed molded article obtained as described above is preferably 10 mm or more, more preferably 20 mm or more, and is not particularly limited as long as it is more than this. If the thickness of the foam molded product is thin, the groove provided on the surface of the foam molded product for sound absorption becomes shallow, and the air layer that can convert sound energy into thermal energy or vibration energy decreases, so sound waves propagate inside the molded product. A sufficient air layer cannot be secured, and viscous friction of air is less likely to occur, resulting in a decrease in sound absorption coefficient. Furthermore, the sound absorption frequency range can be designed by changing the depth of the groove. Therefore, the thicker the molded body, the greater the degree of freedom in designing the sound absorption frequency, which is preferable.

  In addition, the synthetic resin in-mold foam molded article obtained by the mold of the present invention has an excellent sound absorption effect and easy molding processability, so it can be used for various purposes for sound absorption. is there. For example, interior materials for vehicles such as floor spacers, tibia pads, shock absorbers inside pillars, shock absorbers inside door rims, etc., floor materials for buildings such as concert halls and ordinary houses (including core materials that make up floor materials) ) And wall material (including the core material constituting the wall material).

EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example.
Example 1
A mold having a size of 300 × 400 × 60 t (mm) is used, and plate-like members having a thickness of 3 mm, a width of 50 mm, and a height of 50 mm (groove depth of 50 mm) are arranged in three rows and in parallel. It arrange | positioned so that it might become 30 mm of arrangement | positioning space | interval. The pre-expanded particles are made of 30-times Eperan PP manufactured by Kaneka Co., Ltd., which uses polypropylene as the main raw material, and the raw steam is adjusted so that the air pressure in the particles becomes 2.0 atm to give foaming power. Molding was performed at a pressure of 0.32 Mpa. The molded body obtained here was dried at 75 ° C. for 16 hours after molding and then taken out of the drying chamber, left to stand at room temperature for 24 hours or more, and then subjected to sound absorption measurement or compression measurement in an environment at 23 ° C. .
(Example 2)
In the same mold as in Example 1, plate-like members having a thickness of 3 mm, a width of 50 mm, and a height of 40 mm were arranged in three rows and in parallel so as to have an arrangement interval of 30 mm. In-mold molding was performed using pre-expanded particles mainly made of polypropylene (manufactured by Kaneka Corp., Eperan PP expansion ratio of 30 times).
(Example 3)
In the same mold as in Example 1, plate members having a thickness of 5 mm, a width of 50 mm, and a height of 50 mm were arranged in three rows and in parallel so as to have an arrangement interval of 30 mm. In-mold molding was performed using pre-expanded particles mainly made of polypropylene (manufactured by Kaneka Corp., Eperan PP expansion ratio of 30 times).
Example 4
In the same mold as in Example 1, plate-like members having a thickness of 3 mm, a width of 50 mm, and a height of 50 mm were arranged in three rows and in parallel so as to have an arrangement interval of 20 mm. In-mold molding was performed using pre-expanded particles mainly made of polypropylene (manufactured by Kaneka Corp., Eperan PP expansion ratio of 30 times).
(Example 5)
In the same mold as in Example 1, the same number of plate members having a thickness of 3 mm, a width of 50 mm, a height of 40 mm and a height of 50 mm are arranged in three rows and in parallel so that the arrangement interval is 30 mm (short direction: the same height). The plate-like members were arranged in three rows, and the longitudinal direction: plate-like members having a height of 40 mm and 50 mm were alternately arranged). In-mold molding was performed using pre-expanded particles mainly made of polypropylene (manufactured by Kaneka Corp., Eperan PP expansion ratio of 30 times).
(Reference example)
In-mold molding was performed using pre-expanded particles (manufactured by Kaneka Co., Ltd., Eperan PP expansion ratio of 30 times) using polypropylene as the main raw material, using the same mold as in Example 1 without arranging a plate-like member. .
(Comparative Example 1)
Heat absorption at 300 ° C at the tip of the needle-shaped member in an in-mold foam molded body (30 times expansion ratio, Kaneka Co., Ltd.) made of polypropylene as the main raw material, and post-processed with a hole diameter of 2 mm, a pitch of 8 mm, and a hole depth of 40 mm 1700 holes were formed.
(Comparative Example 2)
In order to impart foaming power to pre-expanded particles (eperan PP manufactured by Kaneka Co., Ltd.) with polypropylene as the main raw material, needle-shaped members having a hole diameter of 2 mm and a length of 50 mm are arranged in the mold at a pitch of 8 mm. After adjusting the air pressure in the pre-expanded particles to 2.0 atm, in-mold molding was performed under the same molding conditions as in Example 1. However, there was a portion where the pre-expanded particles could not be filled in part between the needles, and a good foamed molded product could not be obtained.

The sound absorption coefficient of each foamed molded product was calculated by a reverberant sound absorption measurement method using a 9 m ³ reverberation chamber after processing the foamed molded product so as to be 700 mm × 700 mm. The results are shown in FIG.

  Moreover, the compressive strength was measured based on JIS-K6767. The results are shown in Table 1. In Table 1, the opening ratio and compressive strength of the grooves in the examples are shown. Here, the opening ratio of the groove portion is the ratio of the total cross-sectional area of the plate-shaped member of the mold to the product surface area of the one mold where the plate-shaped member is disposed.

  As described above, according to the synthetic resin in-mold foam-molded article produced by the synthetic resin in-mold foam molding mold of the present invention, sound absorption is possible without using special and irregular shaped resin particles in the in-mold foam. It is possible to easily obtain a molded body having a high rate. Furthermore, the compression characteristics are not greatly deteriorated even in comparison with a synthetic resin foam having no sound absorbing groove. Furthermore, it is possible to design the sound absorption frequency range by changing the groove depth, and to make these sound absorption coefficient effects different between the front surface and the back surface of the molded body. In particular, in comparison with a method for producing a sound absorbing material having pores, the number of grooves (number of holes) contributing to sound absorption can be greatly reduced, and this effect enables filling of pre-expanded particles into the mold. As a result, the cost of the mold associated with the sound absorption can be reduced as much as possible.

It is the schematic of a metal mold forming apparatus, and illustrates a part of board member. It is the figure which showed the name of each site | part of a plate-shaped member. It is the figure which showed one of the shape examples of a plate-shaped member. It is the figure which showed the cross-sectional example of the plate-shaped member. It is the figure which showed the example of arrangement | positioning of a plate-shaped member. It is the figure which showed the example of attachment of a plate-shaped member. It is the figure which showed the example of attachment of another plate-shaped member. It is the figure which showed the measurement result of the sound absorption coefficient.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cavity type 2 Core type 3 Molding space 4 Plate-shaped member 5 Eject pin 6 Filler 7 Cavity type vapor chamber 8 Core type vapor chamber 9 Cavity type vapor supply port 10 Core type vapor supply port 11 Cavity type frame 12 Core type frame 13 Cavity type back plate 14 Core type back plate 15 Core vent 16 Cavity type drain port 17 Core type drain port 18 Plate-shaped member fixing base 19 Plate-shaped member and fixing base fixing bolt 20 Plate-shaped member fixing base Fixing bolt 21 Plate-shaped member fixing bolt 22 Burr prevention mold protrusion

Claims (15)

  Foaming is performed by filling pre-expanded particles into a molding space defined by a pair of molding dies composed of a core mold and a cavity mold, and heating the pre-expanded particles with a heating medium to cause foam fusion. In a molding die for obtaining a molded body, foaming in a synthetic resin mold is characterized in that a plurality of plate-like members for providing grooves in the molded body are arranged in at least one of a set of molds. Mold for molding.   2. The synthetic resin in-mold foam molding die according to claim 1, wherein the plate-like member is provided in a first die having an eject pin.   The plate-shaped member is arranged on both the core mold and the cavity mold, and the surface area of the plate-shaped member disposed on the first mold having the eject pin is set to the surface area of the plate-shaped member disposed on the other mold. 2. The synthetic resin in-mold foam molding die according to claim 1, wherein the mold is set to be larger.   A plate-like member is arranged in the other die, with a plate-like member arranged on both the core die and the cavity die, and the taper angle of the plate-like member arranged in the first die provided with the eject pin. The mold for foam molding in a synthetic resin mold according to claim 1 or 2, characterized in that it is set to be equal to or smaller than the taper angle of the above.   The thickness of the said plate-shaped member is 1 mm or more and 10 mm or less, The synthetic resin mold for foam molding as described in any one of Claims 1-4 characterized by the above-mentioned.   The synthetic resin in-mold foam molding die according to any one of claims 1 to 5, wherein an interval between the plate-like members is set to 3 mm or more and 50 mm or less.   The height of the said plate-shaped member is set at least 2 or more, The synthetic resin mold for foam molding as described in any one of Claims 1-6 characterized by the above-mentioned.   The synthetic resin in-mold foam molding die according to any one of claims 1 to 7, wherein at least two or more thicknesses of the plate-like member are set.   The synthetic resin in-mold foam molding die according to any one of claims 1 to 8, wherein the plate members are arranged in parallel, lattice, radial, and concentric circles.   The ratio of the total cross-sectional area of the plate-shaped member of the same mold to the surface area of the foam in one mold on which the plate-shaped member is disposed is 1.5% or more and 15% or less. The synthetic resin mold for foam molding according to any one of claims 1 to 9.   A synthetic resin in-mold foam-molded article manufactured with the synthetic resin in-mold foam molding mold according to any one of claims 1 to 10.   The synthetic resin in-mold foam-molded article according to claim 11, wherein the plurality of grooves of the synthetic resin in-mold foam-molded body are bottomed and / or penetrated.   The vehicle interior material which consists of a synthetic resin in-mold foaming molding of Claim 11 or 12.   The floor material which consists of a synthetic resin in-mold foaming molding of Claim 11 or 12.   The wall material which consists of a synthetic resin in-mold expansion-molding body of Claim 11 or 12.

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