JP5969940B2 - Molding method of foam molded article - Google Patents

Description

  The present invention relates to a method for molding a foamed molded article formed by joining different types of foamed resin materials having the same expansion ratio.

  Conventionally, as a molding method of this type of foamed molded article, a molding apparatus provided with a cavity formed by a fixed mold and a movable mold, and a shutter that slidably protrudes from the fixed mold side with respect to the movable mold to partition the cavity. The first and second cavities partitioned by the shutter are filled with the first foamed resin particles and the other is filled with the second foamed resin particles different from the first foamed resin particles, and the shutter is opened. In addition, a method of heat forming by applying a predetermined vapor pressure is known (for example, Patent Document 1).

  On the other hand, as a combination of the first foamed resin particles and the second foamed resin particles, when considering the weight management of the foamed molded product, a combination of different materials having the same foaming ratio has been demanded. A combination of styrene-modified polyethylene and polyethylene resin having the same magnification is known (for example, Patent Document 2).

Utility Model Registration No. 3176075 JP 2007-83904 A

  However, in the conventional method for molding a foamed molded article, one of a styrene-modified polyethylene and a polyethylene-based resin having the same expansion ratio is filled in the first cavity, and the other is filled in the second cavity. When steam molding is performed by applying vapor pressure, foaming such as the size of the part molded with styrene-modified polyethylene becomes extremely small compared to the part molded with polyethylene-based resin in the molded foam molded product A foamed molded article obtained by joining different kinds of foamed resin materials having the same magnification could not be appropriately molded.

  Then, this invention was made in view of the said problem, and provides the molding method of the foaming molding which can shape | mold appropriately the foaming molding formed by joining different foaming resin materials with the same foaming magnification ratio. Let it be an issue.

  According to the present invention, there is provided a molding method for a foamed molded article using a molding device comprising a cavity formed by closing a pair of molds that can be opened and closed, and a partitioning means for partitioning the cavity. A partitioning step for partitioning the cavity, a filling step for filling the space of the partitioned cavity with a modified polystyrene resin or high impact polystyrene containing polyacrylic acid alkyl ester resin particles, and a cavity different from the one space. A filling step of filling another space with the modified polystyrene resin or a polystyrene resin having the same expansion ratio as the high-impact polystyrene, an opening step of opening the partition by a partitioning means, and 0.04 to 0.12 MPa And a heating step of thermoforming by applying vapor pressure. To.

  According to the molding method of the foamed molded body having such a configuration, a modified polystyrene resin containing polyacrylic acid alkyl ester resin particles or a high-impact polystyrene and a polystyrene resin with the same expansion ratio are employed. In addition, the vapor pressure of thermoforming is set to 0.04 to 0.12 MPa (gauge pressure). With this configuration, the fusion rate between the dissimilar materials can be set to 70% or more, and a dimensional shrinkage rate between the dissimilar materials can be prevented from being generated. That is, when the vapor pressure of thermoforming is smaller than 0.04 Mpa, the fusion rate between the different types of materials becomes 70% or less, and the adhesive force between the different types of materials becomes low. On the other hand, when the vapor pressure of thermoforming is greater than 0.12 Mpa, the fusion rate between the dissimilar materials increases, but a predetermined difference occurs in the dimensional shrinkage rate between the dissimilar materials. Therefore, in the molding method of the foamed molded product, the adhesive pressure between different materials by styrene contained in both materials having the same foaming ratio is improved by setting the vapor pressure of heat molding to 0.04 Mpa or more and 0.12 Mpa or less. In addition, since the dimensional shrinkage ratios of both materials can be made equal or substantially equal, it is possible to appropriately form a foam molded body formed by joining different types of foamed resin materials having the same foaming ratio.

  In addition, the method for molding a foamed molded product according to the present invention uses a molding apparatus including a cavity formed by closing a pair of molds that can be opened and closed, and partition means for partitioning the cavity. A partitioning step of partitioning the cavity by means, a filling step of filling one space of the partitioned cavity with styrene-modified polypropylene resin, and the same space as the styrene-modified polypropylene resin in another space different from the one space A filling step of filling a polypropylene-based resin having a foaming ratio, an opening step of opening the partition by a partitioning means, and a heating step of thermoforming by applying a vapor pressure of 0.2 to 0.5 Mpa are provided. And

  According to the molding method of the foamed molded article having such a configuration, a styrene-modified polypropylene resin and a polypropylene resin having the same foaming ratio are employed, and the heat molding vapor pressure is 0.2 to 0.2. Set to 0.5 MPa (gauge pressure). With this configuration, the fusion rate between the dissimilar materials can be set to 70% or more, and a dimensional shrinkage rate between the dissimilar materials can be prevented from being generated. That is, when the vapor pressure of thermoforming is less than 0.2 Mpa, the fusion rate between the different types of materials becomes 70% or less, and the adhesive force between the different types of materials becomes low. On the other hand, when the vapor pressure of thermoforming is greater than 0.5 Mpa, the fusion rate between the dissimilar materials increases, but a predetermined difference occurs in the dimensional shrinkage rate between the dissimilar materials. Therefore, in such a molding method of the foamed molded article, the adhesive pressure between different materials by propylene contained in both materials having the same foaming ratio is improved by setting the vapor pressure of thermoforming to 0.2 Mpa or more and 0.5 Mpa or less. In addition, since the dimensional shrinkage ratios of the two materials can be made substantially equal, a foamed molded body formed by joining different types of foamed resin materials having the same foaming ratio can be appropriately molded.

  According to the method for molding a foamed molded article of the present invention, it is possible to improve the adhesive force between different materials by styrene or propylene contained in both materials having the same expansion ratio and to make the dimensional shrinkage ratios of both materials equal or substantially equal. Therefore, there is an effect that it is possible to appropriately form a foam molded body formed by joining different types of foamed resin materials having the same expansion ratio.

The state before closing a pair of shaping | molding die of a shaping | molding apparatus in the shaping | molding method of the foaming molding which concerns on this embodiment is shown. A state in which the same pair of molds are closed and the foamed resin particle material is filled in the cavity partitioned by the partitioning means is shown. The state by which the partition by the partition means is opened and thermoformed is shown. A state in which the same pair of molds is opened in order to take out (release) the molded foam molded article is shown. The perspective view of the foaming molding concerning this embodiment is shown.

  Hereinafter, an embodiment of a method for molding a foam molded body according to the present invention will be described with reference to FIGS. 1 to 4. In such a molding method of a foam molded article, a molding apparatus 1 as shown in FIG. 1 is used.

  The molding apparatus 1 of the present embodiment includes a pair of molds 2 and 3 that can be opened and closed for filling foamed resin particles to mold a foamed molded body. Specifically, as shown in FIG. 1, the molding apparatus 1 includes one molding die 2 that is fixedly installed (hereinafter referred to as a fixed die 2) and the other molding die 3 that is movably installed (hereinafter referred to as “molding die 2”) Mobile type 3). In this molding apparatus 1, the fixed mold 2 has a first mold 2 </ b> A, the movable mold 3 has a second mold 3 </ b> A, and the movable mold 3 is brought close to the fixed mold 2, so that the first mold A cavity (molding space) is formed by bringing 2A and the second mold 3A close to each other or abutting (closed) to form a foam molded article.

  The fixed mold 2 of the present embodiment includes a first mold 2A formed in a convex shape or a concave shape along the opening / closing direction, and the first mold 2A on the back side (the side where no cavity is formed) of the first mold 2A. And a back plate 2B for supporting A space formed by the first mold 2A and the back plate 2B is a steam chamber 2C. Further, the first mold 2A has a vent (steam hole) 2D for supplying steam from the steam chamber 2C to the cavity and a concave side part into which a side part of a shutter 21 described later is fitted (or inserted). A groove 2E is provided.

  The fixed mold 2 includes a flat shutter (partitioning means) 21 for partitioning the cavity, and an opening / closing mechanism 22 that slides the shutter 21 between a partition position L1 for partitioning the cavity and an open position L2 for opening the partition. And are provided. Further, the fixed mold 2 includes a filling device 23 for filling the cavity with foamed resin particles, and a mold release means (not shown) for extruding the foam molded body molded in the cavity from the first mold 2A. Not).

  The movable mold 3 according to the present embodiment includes a second mold 3A that is formed in a convex shape or a concave shape along the opening / closing direction and that forms a pair with the first mold 2A, and a back side (a cavity is formed) of the second mold 3A. And a back plate 3B that supports the second mold 3A (see FIG. 1). A space formed by the second mold 3A and the back plate 3B is a steam chamber 3C. Further, the second mold 3A has a concave end groove for fitting (or inserting) a vent (steam hole) 3D for supplying steam from the steam chamber 3C to the cavity and one end 21a of the shutter 21. 3E.

  As shown in FIGS. 1 to 4, the molding method of the foam molded body of the present embodiment using the molding apparatus 1 includes a partition step for partitioning the cavity by the shutter 21, and a first space S <b> 1 of the partitioned cavity. The filling step of filling the first foamed resin particle R1 and the second foamed resin particle having the same foaming ratio as that of the first foamed resin particle R1 (including substantially the same) in the second space S2 of the cavity different from the one space S1. It comprises a filling step for filling R2, an opening step for opening the partition by the shutter 21, and a heating step for applying heat molding by applying a predetermined vapor pressure. More specifically, in the molding method of the foam molded body of the present embodiment, the first foamed resin particles R1 are filled in the first space S1 of the partitioned cavity by moving the shutter 21 to the partition position L1. The second space S2 is filled with the second foamed resin particles R2, the shutter 21 is moved to the open position L2, the partition is opened, a predetermined vapor pressure is applied and heat molding is performed, and the expansion ratio is the same ( A foamed molded article obtained by joining different kinds of foamed resin materials (including substantially the same) is obtained.

  Specifically, the cavity 3 is formed by the first mold 2A and the second mold 3A by bringing the movable mold 3 close to the fixed mold 2 (see FIG. 1) and closing the pair of molds 2 and 3. . Then, the shutter 21 is moved from the open position L2 to the partition position L1 to partition the cavity into the first space S1 and the second space S2 adjacent to the first space S1 (see FIG. 2). At this time, the side part of the shutter 21 is fitted into the side groove 2E of the first mold 2A, and the one end part 21a of the shutter 21 is fitted to the one end groove 3E of the second mold 3A. .

  The first foamed resin particles R1 and the second foamed resin particles R2, which are different materials having the same expansion ratio (including substantially the same), are filled in the first space S1 and the second space S2 of the cavity by the filling device 23, respectively. Filled (see FIG. 2). In the present embodiment, the first space S1 is filled with a modified polystyrene resin or high impact polystyrene containing polyacrylic acid alkyl ester resin particles as the first foamed resin particles R1, and the second space S2. Thus, the polystyrene resin having the same expansion ratio (including substantially the same) as the first foamed resin particle R1 is filled as the second foamed resin particle R2.

  Here, as the polystyrene resin of the second foamed resin particle R2, for example, a polystyrene polymer can be used. Polystyrene polymers include, for example, styrene, methyl styrene, ethyl styrene, isopropyl styrene, dimethyl styrene, paramethyl styrene, chlorostyrene, bromostyrene, vinyl toluene, vinyl xylene homopolymer or copolymer, and styrene-anhydrous maleic. It can be composed of one or more selected from the group consisting of acid copolymers, styrene-acrylic acid copolymers, and styrene-methacrylic acid copolymers.

  Further, the modified polystyrene resin of the first foamed resin particle R1 is obtained by dispersing polyacrylic acid alkyl ester resin fine particles in a polystyrene resin, for example, a ratio of styrene and polyacrylic acid alkyl ester resin fine particles. Can be configured as 9: 1. Further, the high impact polystyrene of the first foamed resin particle R1 has the performance of improving the impact strength (impact resistance) of the polystyrene, such as one or more of butadiene rubber, ethylene-propylene rubber, and styrene-butadiene rubber. It can be constituted by copolymerizing a polystyrene polymer.

  After filling the first space S1 with the first foamed resin particles R1 and the second space S2 with the second foamed resin particles R2 by the filling device 23, the shutter 21 is moved from the partition position L1 to the open position L2. Then, the cavity partition is opened (see FIGS. 2 and 3). At this time, the first foamed resin particle R1 and the second foamed resin particle R2 are filled into the partition position L1 in the cavity that was located before the shutter 21 moved to the open position L2 (see FIG. 3).

  Subsequently, the foamed resin particles were heated and foamed by supplying steam having a pressure of 0.04 to 0.12 Mpa (gauge pressure) from the steam chambers 2C and 3C through the vents 2D and 3D to the molding space. Then cool down. Thereafter, the movable mold 3 is separated from the fixed mold 2 and the pair of molds 2 and 3 are opened (see FIG. 4), and the foamed molded body 4 is pushed away from the fixed mold 2 by a mold release means.

  The foamed molded body 4 thus molded is used as a vehicle member (for example, a lower limb impact absorbing pad or a core material of a floor spacer) as shown in FIG. When the foamed resin particle R1 and the second foamed resin particle R2 are fused at the joint interface J, the portion where the first foamed resin particle R1 is molded and the portion where the second foamed resin particle R2 is molded are joined. Joined at the interface J. The portion of the foamed molded body 4 where the first foamed resin particles R1 are molded has an impact absorbing performance than the portion where the second foamed resin particles R2 are molded. The portion where the first foamed resin particle R1 is molded and the portion where the second foamed resin particle R2 is molded have the same density or specific gravity and the same porosity. Further, on the outer periphery of the bonding interface J between the first foamed resin particle R1 and the second foamed resin particle R2 of the foam molded body 4, the side groove 2E and the one end groove 3E in the pair of molds 2 and 3 are provided. Convex ridges 41 filled with foamed resin particles and formed are formed (see FIGS. 4 and 5). Since this protrusion 41 becomes a mark as a marking line for additional work, the work efficiency of the operator can be improved when the foamed molded body 4 is additionally processed.

  In the foamed molded body 4, the dimensional shrinkage rate in the portion where the first foamed resin particle R1 is molded is about 0.3 to 0.5%, and the dimensional shrinkage in the portion where the second foamed resin particle R2 is molded. The rate is about 0.2 to 0.3%. Therefore, in such a foamed molded article 4, one of the dimension in which the first foamed resin particle R1 is molded and the part in which the second foamed resin particle R2 is molded is extremely extreme with the joint interface J as a boundary. There is no dimensional mismatch such as small. In addition, at the bonding interface J, the adhesive strength (or fusion power) between different materials is improved by styrene contained in the first foamed resin particles R1 and the second foamed resin particles R2 having the same expansion ratio (including substantially the same). As a result, since the bonding strength is improved, cracks and breaks at the bonding interface J are unlikely to occur. Further, since the first foamed resin particle R1 and the second foamed resin particle R2 have the same foaming ratio, the molded foam molded body 4 can be easily weight-controlled, for example, an energy absorbing material based on weight management. It is possible to stabilize the quality by suppressing variations in the shock absorbing performance.

  Further, in the foamed molded body 4, the fusion rate between the first foamed resin particles R1 and the second foamed resin particles R2 can be increased by setting the vapor pressure of thermoforming to 0.04 to 0.12 Mpa (gauge pressure). It is 70% or more, and the dimensional shrinkage ratio between the first foamed resin particle R1 and the second foamed resin particle R2 is equal or substantially equal as described above. In this regard, when the vapor pressure of the heat forming is smaller than 0.04 Mpa, the adhesion rate between the dissimilar materials becomes low with the fusion rate being 70% or less, and the vapor pressure of the heat forming is larger than 0.12 Mpa. In this case, the fusion rate is increased, but a predetermined difference (for example, a predetermined difference that causes a difference in the outer dimension of several mm or more that may affect the quality) occurs in the dimensional shrinkage rate between different kinds of materials. End up.

  As described above, in the molding method of the foam molded article of this embodiment, the expansion ratio of the modified polystyrene resin or high impact polystyrene containing the polyacrylic acid alkyl ester resin particles and the polystyrene resin is the same. By adopting a material and setting the vapor pressure of thermoforming to 0.04 to 0.12 Mpa, the adhesive force between dissimilar materials due to styrene contained in both materials having the same expansion ratio is improved, and both materials Therefore, it is possible to appropriately mold the foam molded body 4 formed by joining different types of foamed resin materials having the same foaming ratio.

  Moreover, the molding method of the foamed molded product according to another embodiment is the same as the method of molding the foamed molded product of the above embodiment, in the combination of the first foamed resin particle R1 and the second foamed resin particle R2, and during the heat molding. The vapor pressure is changed. Specifically, the first foamed resin particle R1 is a styrene-modified polypropylene resin, and the second foamed resin particle R2 is a polypropylene having the same expansion ratio (including substantially the same) as the styrene-modified polypropylene resin. Consists of resin. Further, at the time of thermoforming, the foamed resin particles are configured to be heated by supplying steam having a pressure of 0.2 to 0.5 MPa (gauge pressure) to the molding space. For example, 0.2 to 0.3 Mpa or 0.3 to 0.5 Mpa can be used as the vapor pressure.

  Here, the polypropylene resin of the second foamed resin particle R2 is a propylene homopolymer or a copolymer of a propylene monomer as a main component and another monomer component copolymerizable with the propylene monomer. For example, propylene homopolymer, ethylene-propylene copolymer having propylene monomer as a main component, propylene-acrylic acid copolymer, propylene-α-olefin copolymer, propylene-acetic acid It can be composed of polymers such as vinyl copolymers and propylene-methyl methacrylate copolymers. The styrene-modified polypropylene resin of the first foamed resin particle R1 can be configured by polymerizing styrene with the polypropylene resin as a core.

  In the foamed molded product molded by the foamed molded product molding method of the other embodiment, the dimensional shrinkage ratio in the portion where the first foamed resin particle R1 is molded is about 0.6 to 1%, and the second foamed product is formed. The dimensional shrinkage rate at the portion where the resin particle R2 is molded is about 1.5 to 2%. Therefore, in such a foamed molded product, one of the dimension in which the first foamed resin particle R1 is molded and the part in which the second foamed resin particle R2 is molded is extremely small with the joint interface as a boundary. Such a dimensional mismatch does not occur. In addition, at the bonding interface, the bonding strength between different materials is improved by the propylene contained in the first foamed resin particles R1 and the second foamed resin particles R2 having the same expansion ratio (including substantially the same), so that the bonding strength is increased. Since it is improved, cracks and fractures at the joint interface are unlikely to occur.

  Further, in this foamed molded article, the fusion rate between the first foamed resin particles R1 and the second foamed resin particles R2 is 70 by setting the vapor pressure of thermoforming to 0.2 to 0.5 Mpa (gauge pressure). % And the dimensional shrinkage rate of the first foamed resin particle R1 and the second foamed resin particle R2 is substantially equal as described above. In this regard, when the vapor pressure of heat forming is less than 0.2 Mpa, the fusion rate is 70% or less and the adhesion between different materials is reduced, and the vapor pressure of heat forming is greater than 0.5 Mpa. In such a case, the fusion rate is increased, but a predetermined difference occurs in the dimensional shrinkage rate between different kinds of materials.

  As described above, in the molding method of the foamed molded product according to another embodiment, the same styrene-modified polypropylene resin and polypropylene resin having the same foaming ratio are employed, and the vapor pressure of thermoforming is 0. .2 to 0.5 Mpa improves the adhesive force between different materials with propylene contained in both materials having the same expansion ratio, and the dimensional shrinkage ratio of both materials can be made substantially equal, so the expansion ratio is the same. It is possible to appropriately form a foam molded body formed by joining different kinds of foamed resin materials.

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of this invention. For example, in the above embodiment, the case where one mold 2 is a fixed mold and the other mold 3 is a movable mold has been described. However, one and the other molds 2 and 3 are in contact with each other. It is also possible to constitute a movable type that can be separated. Alternatively, one mold 2 can be a movable mold and the other mold 3 can be a fixed mold.

  Moreover, although the said embodiment demonstrated the case where the shutter 21 partitions a cavity into two of 1st space S1 and 2nd space S2, two or more flat shutters 21 are provided in a shaping | molding apparatus, and the shutter 21 is a cavity. It is also possible to divide the space into two or more spaces. In this case, one of the plurality of spaces adjacent to each other can be filled with the first foamed resin particles R1 and the other with the second foamed resin particles R2.

  Moreover, in the said embodiment, the timing which fills 1st foamed resin particle R1 in 1st space S1, and the timing which fills 2nd foamed resin particle R2 in 2nd space S2 are simultaneous, or any one is either Any of the previous configurations are possible. Further, while filling the first foamed resin particles R1 and / or the second foamed resin particles R2 into the respective spaces, the shutter 21 is moved from the partition position L1 to the open position L2 to open the partition of the cavity, It is also possible to heat mold while opening the partition.

  Moreover, although the said embodiment demonstrated the case where a foaming molding was used for the core material of a leg extremity impact-absorbing pad as vehicle members, such as a motor vehicle, it is not limited to this use, It can be used for various uses. it can. For example, the foamed molded product can be used for automobile bumpers, door pads, containers, packing materials, and the like. Moreover, a foaming molding can be comprised by various shapes according to a use.

As an explanation of terms used in this specification, the definition of “fusion rate” will be described. First, using a molding apparatus capable of molding a planar substantially rectangular plate-like foam molded body, the cavity is partitioned by a shutter so as to be parallel to one side of the cavity forming the plate-like space, and one and the other of the partitioned cavities Each plate is filled with a different material, and the shutter is opened and heat-molded to form a plate-like foam molded article. And a plate-shaped foaming molding is fractured | ruptured in the direction orthogonal to the said one side. At this time, using the total number of particles (A) counted within an arbitrary range in which 100 to 150 foamed particles are included in the fracture surface, and the number of broken particles (B), the following The fusing rate (%) is defined as an equation. Such a fusion rate can be evaluated as 70% or higher as good and less than 70% as defective.

  In addition, the definition of “dimensional shrinkage rate” used in this specification will be described. First, as described in the definition of “fusion rate” above, a plate-like foamed molded article is molded. At this time, the foam-molded body is foam-molded with dimensions of 300 mm in length, 400 mm in width, and 10 mm in height. With respect to the dimension immediately after the molding, the dimension after the passage of 16 hours or more under a temperature condition of 23 ° C. A value obtained by measuring the rate of change according to JIS K6767: 1999 is the “dimensional shrinkage rate” of the foamed molded product.

  DESCRIPTION OF SYMBOLS 1 ... Molding device, 2 ... Fixed mold (one mold), 2A ... 1st mold, 2B ... Back plate of 1st mold, 2C ... Steam chamber of 1st mold, 2D ... First mold Vent, 2E ... side groove of first mold, 21 ... shutter (partitioning means), 22 ... opening / closing mechanism, 23 ... filling device, 3 ... moving mold (other mold), 3A ... second mold, 3B: Back plate of the second mold, 3C: Vapor chamber of the second mold, 3D: Vent of the second mold, 3E: Groove for one end of the second mold, 4 ... Foam molded body, 41 ... Projection Part, J ... joining interface, L1 ... partition position, L2 ... open position, R1 ... first foamed resin particles, R2 ... second foamed resin particles, S1 ... first space, S2 ... second space

Claims (2)

Using a molding apparatus comprising a cavity formed by closing a pair of molds that can be opened and closed, and a partitioning means for partitioning the cavity,
A partitioning step for partitioning the cavity by partitioning means;
A filling step of filling one space of the partitioned cavity with a modified polystyrene resin or high impact polystyrene containing polyacrylic acid alkyl ester resin particles;
A filling step of filling the other space of the cavity different from the one space with a polystyrene resin having the same expansion ratio as the modified polystyrene resin or the high impact polystyrene;
An opening step of opening the partition by the partition means;
And a heating step of heating and forming by applying a vapor pressure of 0.04 to 0.12 Mpa. Using a molding apparatus comprising a cavity formed by closing a pair of molds that can be opened and closed, and a partitioning means for partitioning the cavity,
A partitioning step for partitioning the cavity by partitioning means;
A filling step of filling a space in the partitioned cavity with a styrene-modified polypropylene resin;
A filling step of filling the other space of the cavity different from the one space with a polypropylene resin having the same expansion ratio as the styrene-modified polypropylene resin;
An opening step of opening the partition by the partition means;
And a heating step of heat forming by applying a vapor pressure of 0.2 to 0.5 Mpa.

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