JP6093588B2 - Manufacturing method and apparatus for manufacturing foamed article with skin - Google Patents

Description

  The present invention relates to a method for producing a foam-molded article with a skin and a production apparatus therefor, and more specifically, a foam-molded article with a skin obtained by filling foam particles into a hollow molded body formed by blow molding and performing in-mold molding. The present invention relates to a manufacturing method and a manufacturing apparatus thereof.

  Conventionally, a parison extruded from an extruder is blow-molded in a blow molding die to form a hollow molded body, the foamed particles are filled into the hollow molded body, and heated steam is introduced into the hollow molded body. A method for producing a foamed molded article with a skin in which the foamed particles are fused together is known (Patent Document 1).

  In addition, a method for filling a hollow molded body by blow-molding a parison extruded from an extruder in a blow molding die and filling the hollow molded body with thermoplastic resin expanded particles is described below. There is known a filling device for perforating a filling port using a filling feeder device equipped with a rotary drive type cutter, and a manufacturing method for obtaining a foamed particle molded body with a skin using the device (Patent Document 2). ). Specifically, a method is provided in which a rotary cutter is provided on the front surface of the plunger cylinder of the filling feeder device, the plunger cylinder is advanced while rotating, and the particle filling port is opened in the hollow molded body by the rotary cutter. Is disclosed.

Japanese Patent Laid-Open No. 6-182887 JP-A-6-182862

  When the foamed particles are filled into a hollow molded body formed by blow molding to produce a foamed molded body with a skin, a filling port for filling the foamed particles into the hollow molded body is opened. At this time, when a rotary cutter is used, there is a problem that a space for a rotary drive device is required, and the foamed particle filling device becomes large. In addition, a cylinder for rotating the cutter is necessary, and the cost of the filling device is high.

  Also, depending on the type of resin of the hollow molded body that forms the skin, the workability of drilling to provide a filling port may be poor. In particular, when the resin constituting the hollow molded body is a polyolefin resin typified by polypropylene or polyethylene, since the ductility is high as a characteristic of the resin, the foamed particle filling port is opened in the hollow molded body forming the skin. The molding cycle time required for the process becomes longer and the productivity is inferior.

  As a method of drilling the foamed particle filling port without using the rotary cutter described above for a hollow molded body formed of a resin having high ductility, (1) a hole punching cutter after the hollow molded body is sufficiently cooled Can be considered, such as (2) lengthening the stroke of punching the hollow cutter into the hollow molded body, and (3) reducing the diameter of the filling port. However, in the method (1), the molding cycle time is significantly increased, the hollow molded body that is the skin is cooled, and the adhesiveness between the foamed particles and the skin due to steam heating becomes insufficient. There was a risk that the physical properties such as the mechanical strength of the resin would deteriorate. In the case of (2), it is possible to make a hole by increasing the thickness of the molded body at the portion where the opening for filling is provided and increasing the protrusion amount (setting stroke width) of the cutter. In addition, when a product with a small thickness is obtained, there is a drawback that the shape is restricted in that holes cannot be formed in the thickness direction. In addition, the method (3) has the disadvantage that the amount of foam particles filled from the filling port is limited and the filling time takes a long time, resulting in inferior productivity. In addition, a particle bridging occurs near the filling port, resulting in poor filling. In some cases, this was likely to occur.

  The present inventors aim to provide a production method capable of easily obtaining a foamed article with a skin, and blow-mold a soft parison formed by extruding a thermoplastic resin melt in a mold cavity. In the method for producing a foam-molded article with a skin, the hollow molded article is molded, the foamed particles are filled into the hollow molded article, and then the heating particles are supplied to the hollow molded article to heat-fuse the foamed particles. As a result of various investigations regarding the above-described problems, such as a method for forming a hollow molded body, a method for opening a foamed particle filling port, and a manufacturing apparatus, the inventors have achieved the following present invention.

  Here, in the present specification, the foam-molded body with a skin may be simply referred to as “foam-molded body”. Further, the hollow molded body is sometimes referred to as “skin”, and the foamed particle filling device is also simply referred to as “filling device”.

The present invention relates to a method for producing a foamed molded article with a skin having the structure described in [1] to [ 6 ] below, and a production apparatus therefor.

[1] A thermoplastic resin melt is extruded to form a soft parison, and the parison is blow-molded in a mold cavity to form a hollow molded body, and then the hollow molded body is thermoplastic in the molded body. A foamed molded article with a skin provided with a filling port for filling resin foam particles, filling the foamed particles from the filling port, supplying a heating medium into the hollow molded body and heat-sealing the foamed particles. In the manufacturing method, when the parison is blow-molded, the parison is brought into contact with an annular projecting portion formed to project from the mold cavity surface in the inner direction of the mold cavity, and the hollow molded body is formed. Forming an annular recess corresponding to the shape of the projecting portion and inserting a punching blade along the inner surface of the projecting portion to form the filling port inside the annular recess, Manufacturing method ,
[2 ] The projecting portion is formed by projecting the tip of the foam particle filling tube for filling the foam particles from the mold cavity surface, and the punching blade extends along the inner surface of the foam particle filling tube. The method for producing a foam-molded article with a skin according to the above [1], wherein the foam-molded pipe is provided so as to be inserted into the hollow molded article .
[ 3 ] The method for producing a foamed molded article with a skin according to [1] or [2], wherein the punching blade has a cylindrical shape, and an end surface of a tip portion of the punching blade is recessed in a concave shape. ,
[ 4 ] The method for producing a foam-molded article with a skin according to any one of [1] to [ 3 ], wherein a height a of the protrusion from the mold cavity surface is 1 to 7 mm. ,
[ 5 ] The method for producing a foam-molded article with a skin according to any one of the above [1] to [ 4 ], wherein the thermoplastic resin constituting the thermoplastic resin melt is made of a polyolefin resin .
[ 6 ] A mold for forming a hollow molded body by blow-molding a soft parison formed by extruding a thermoplastic resin melt in a mold cavity, a foam particle-filled tube filled with foam particles, An apparatus for producing a foam-molded article with a skin provided with a punching blade for drilling a filling port for foamed particles, wherein the foamed particle-filled tube has a tip portion of a mounting portion to the mold from the mold cavity surface to the inside of the cavity. The punching blade is provided so as to protrude from the tip of the foam particle filling tube into the mold cavity along the inner surface of the foam particle filling tube. An apparatus for producing a foamed molded article with a skin ,
Is the gist.

  According to the manufacturing method of the present invention, a softened parison is brought into contact with an annular projecting portion formed to project into a mold cavity and blow-molded to form an annular recess in a hollow molded body. A punching blade is inserted along the inner surface to form a foam particle filling port inside the annular recess. By forming the concave portion in the hollow molded body, the resin of the portion that is inserted and punched by the punching blade is locally stretched and thinned, and the punching hole processing can be easily performed. Therefore, the resin constituting the hollow molded body forming the skin is not stretched following the punching with the punching blade, and the foamed particle filling port can be easily punched.

  According to another manufacturing method of the present invention, the hollow molding corresponding to the shape of the projecting portion is blow-molded by bringing the softened parison into contact with the projecting portion projecting into the mold cavity. A recessed portion recessed inside the body is formed in a hollow molded body, a punching blade is inserted into the recessed portion, and the recessed portion is punched with a punching blade to form a foam particle filling port. Similarly to the above, by forming the recess in the hollow molded body, the resin of the portion punched by the punching blade is locally stretched and thinned, and punching hole processing can be easily performed. Therefore, the resin constituting the hollow molded body forming the skin is not stretched following the punching with the punching blade, and the foamed particle filling port can be easily punched.

  These effects are particularly excellent in the opening effect for soft resins and polyolefin resins, which are considered difficult to form the foamed particle filling port. In addition, the punched foam particle filling port has a fine finish and can be filled quickly without causing poor filling of the foam particles. Further, there is an advantage that the molding cycle can be shortened.

  In addition, since the punching length of the punching blade can be made shorter than before, for example, in the foamed molded body with a flat-plate skin, the foamed particle filling port is also formed in the thickness direction of the thin flat plate. Thus, the expanded particles can be filled. Therefore, the degree of freedom of the shape of the molded product is increased, and a molded product having a thin product thickness and a large skin thickness can be formed.

  Furthermore, since the manufacturing apparatus of the present invention can easily open the filling port without rotating the punching blade, the filling apparatus can be reduced in size as compared with a filling apparatus having a rotary cutter, and with rotation. There is no danger such as chipping of the cutter.

It is sectional drawing of the expanded particle filling apparatus provided with the expanded particle filling tube which concerns on the manufacturing method of this invention. It is sectional drawing which shows the principal part of the front-end | tip part state of the mounting state to the metal mold | die of the expanded particle filling tube of this invention. It is explanatory drawing which shows the principal part of the manufacturing process of the foaming molding with a skin of this invention, shows the state which carried out the blow molding of the parison and formed the recessed part in the hollow molding body (skin) in the mold cavity. A punching blade is protruded and inserted into a hollow molded body, and a foamed particle filling port (opening) is formed by punching holes. The punching blade is retracted to a predetermined position, and the expanded particles are filled from the filling port. After filling the expanded particles, the expanded particles are fused with steam. It is sectional drawing which shows an example of the outline of the manufacturing apparatus of a foaming molding with a skin.

  The present invention is for extruding a thermoplastic resin melt to form a softened parison, blow molding the parison to form a hollow molded body, and then filling the hollow molded body with thermoplastic resin foam particles. The present invention relates to a method for manufacturing a foamed molded article with a skin, and a manufacturing apparatus for the same, in which a filling port is provided, the foamed particles are filled from the filling port, a heating medium is supplied into the hollow molded body, and the foamed particles are heated and fused. .

  According to a first aspect of the present invention, in the manufacturing method, when the parison is blow-molded in the mold cavity, the parison is applied to a protrusion formed on the mold cavity surface so as to protrude inward of the cavity. The present invention relates to a method for producing a foamed molded article with a skin, wherein a concave portion corresponding to the shape of the protruding portion is formed in the hollow molded body and the filling port is formed by inserting a punching blade.

  According to a second aspect of the present invention, a mold for forming a hollow molded body by blow-molding a soft parison formed by extruding a thermoplastic resin melt in a mold cavity, and foaming for filling expanded particles An apparatus for producing a foam-molded article with a skin comprising a particle-filled tube and a punching blade for drilling a filling port for the foamed particle, wherein the foamed particle-filled tube has a die at the tip of the connecting portion to the mold. The punching blade protrudes from the cavity surface toward the inside of the mold cavity and is attached to the mold, and the punching blade extends along the inner surface of the foam particle filling tube from the tip of the foam particle filling tube into the mold cavity. The present invention relates to an apparatus for producing a foam-molded article with a skin, characterized in that it is provided so as to be able to project toward the surface.

  Since the manufacturing apparatus of the present invention does not require a conventional rotary cutter or the like, it can greatly reduce the installation space for the foam particle filling device, shorten the molding cycle, and provide a foam particle filling port that is cleaner than before. Can be formed.

  The production method of the foamed molded article with a skin according to the present invention will be described in detail. A soft parison formed by extruding a thermoplastic resin melt from an extruder is placed in a mold cavity for molding, The mold was closed, a pressurized gas (usually air) was blown into the parison from the blow gas introduction tube, blow molding was performed, and the outer surface of the hollow molded body was in contact with the inner surface of the mold cavity to reflect the cavity inner surface shape. A hollow molded body that forms the skin is molded.

  According to the manufacturing method of the present invention, when the parison is blow-molded, the parison is brought into contact with a protruding portion formed to protrude from the mold cavity surface toward the inside of the cavity, and is pressed into the parison. By blowing the gas, a recess corresponding to the shape of the protrusion is formed in the inner direction of the hollow molded body. In addition, it is preferable that the protrusion part formed in said metal mold | die cavity surface forms the cyclic | annular protrusion part. In addition, it is preferable that the tip of the attachment connecting portion to the mold in the foamed particle filled tube is formed so as to protrude from the mold cavity surface toward the inside of the cavity, and the protruding portion is used as the protruding portion.

In the present invention, when the parison disposed in the mold cavity is blow molded, the outer surface (mold side) of the parison is brought into contact with the projecting portion projecting into the mold cavity. A recess C1 corresponding to the shape of the protrusion is formed. In addition, a recessed part becomes a shape depressed in the internal direction of the hollow molded object. FIG. 3 schematically shows the state.
In addition, it is preferable that the bottom part of the said recessed part C1 is in the state somewhat depressed on the said foaming particle filling tube side, as illustrated in FIG.

  Moreover, although the state in which the hollow molded body (resin) forming the concave portion is in close contact with the peripheral portion of the protruding portion 7 is illustrated, it is not always necessary to be completely in close contact, and the hollow in which the concave portion is formed. What is necessary is just to become the shape dented inside the parison from the circumference | surroundings of a molded object.

  In the blow molding for forming the hollow molded body, when the concave portion is formed by the pressurized gas blown into the parison, the soft parison forming the concave portion is brought into contact with the protruding portion 7 and stretched. It becomes thin, and it becomes a shape that can be easily punched by a punching process in which a punching blade is inserted into the recess. Accordingly, when the foaming particle filling port is opened by the punching blade, the concave portion is formed in advance, so that when the punching blade is inserted into the concave portion and the concave portion is punched, the resin in the concave portion is stretched. It can be cut easily and neatly, and the foamed particle filling port can be easily drilled.

  When the hollow is not formed with the recess, the foamed particle filling port cannot be easily drilled or the foamed particle filling port is opened cleanly by the resin in the drilled part being stretched by the punching blade. This is not possible, which may hinder the filling of the foamed particles and may make it difficult to shorten the molding cycle.

  When a pressurized gas (usually air) is blown into the softened parison to form a hollow molded body, the hollow molded body is reduced in pressure between the outer surface of the parison and the inner surface of the mold cavity. Is preferable because the hollow molded body can be shaped to reflect the shape of the mold cavity and the recess can be easily formed.

  The foamed particle filled tube is formed with a protruding portion formed by protruding the tip end portion of the attachment connecting portion to the mold from the mold cavity surface toward the inside of the cavity. The foamed particle filling tube is connected to a flow path for filling the foamed particles, and the foamed particles can be filled through the protruding portion.

  FIG. 7 shows an example of an outline of a manufacturing apparatus for a foam-molded article with a skin. The foam particle filling apparatus 1 is attached to one mold of a split mold, and the steam supply pin 2 is inserted into the cavity from the other mold. It is sectional drawing which shows an example of the outline of the manufacturing apparatus currently used.

The manufacturing process and manufacturing apparatus in the manufacturing method of the present invention will be described in detail with reference to FIGS.

  Specific examples of the expanded particle filling apparatus including the expanded particle filling tube used in the present invention are shown in FIGS. 1 and 2. FIG. 1 is a cross-sectional view of a foamed particle filling apparatus provided with a foamed particle filled tube, and FIG. 2 is a cross-sectional view showing a main part of a tip portion of the foamed particle filled tube attached to a mold.

The filling device 1 is generally composed of a spindle 3, a punching blade 4 attached to the tip of the spindle 3, and a cylinder 5 that drives the spindle 3 back and forth.
The filling device 1 is formed with a projecting portion made of a foam particle filling tube and attached to one mold of the split mold, and the projecting portion projects the tip of the foam particle filling tube from the mold cavity surface. It is formed by. Furthermore, a foamed particle supply path 11 connected to the foamed particle filling pipe and a pressurized air flow path 12 for foamed particle pressure feeding are installed facing each other. The expanded particle supply path 11 is connected to a flexible tube (not shown) and communicates with an expanded particle storage tank (not shown). The foamed particle filled tube is provided with the punching blade so as to project from the projecting portion toward the hollow molded body in the mold cavity along the inside of the foamed particle filled tube.

  The recessed portion indicated by reference numeral C1 formed in the hollow molded body is formed by advancing the punching blade from the standby position as shown in FIG. By projecting inward, the punching blade is inserted into the recess, the recess is punched, and the foamed particle filling port is formed. After the drilling, the punching blade 4 is retracted to the standby position as shown in FIG. 1, and then the foamed particle supply passage 11 and the pressurized air passage 12 for feeding foam particles are opened and closed. Is filled into the hollow molded body.

  An example of the outline of the process of manufacturing the foam-molded body with a skin by the method of the present invention will be described with reference to FIGS. FIG. 3 shows a mounting part of a foamed particle filling tube of a foamed particle filling apparatus connected to a mold, and a protruding part is formed from the mold cavity surface into the mold cavity. It shows a state in which a parison is blow-molded in the mold having the structure of the present invention to form a hollow molded body (skin) in the mold cavity. That is, the tip of the expanded particle filling tube 6 to the mold of the filling device is protruded into the mold cavity to form the protruding portion 7, and the filling device is mounted. Then, in the mold cavity, a soft parison is disposed and blow-molded, and the parison is brought into contact with the projecting portion 7 by blow air, so that a concave portion C1 corresponding to the shape of the outer wall of the projecting portion is obtained. Is formed so as to protrude in the inner direction of the hollow molded body. In addition, when forming a recessed part, it is preferable that the front-end | tip of a punching blade exists in the position which does not protrude from the vertex of a protrusion part, as shown in FIG. Furthermore, it is preferable from the viewpoint of punching holes that the tip of the punching blade is in the vicinity of the mold cavity surface. When the tip of the punching blade is in the vicinity of the mold cavity surface, no hole is formed in the bottom surface portion of the recess C1, and the parison is appropriately stretched in the direction of the punching blade. It becomes convex. The position of the tip of the punching blade when forming the recess is preferably within 4 mm in the front-rear direction from the mold cavity surface.

  Further, as shown in FIG. 3, when the projecting portion is formed in an annular shape, an annular recess corresponding to the shape of the outer wall of the annular projecting portion and the inner wall of the annular projecting portion (hereinafter sometimes referred to as an annular recess). Is formed. In this case, the parison is stretched to the outer wall side of the projecting portion by blow air, and the parison is also stretched in the direction of the inner wall of the annular portion, so that the punching hole processing becomes easier.

  FIG. 4 shows a state in which a recess formed in the hollow molded body is punched to form a filling port (opening). That is, after forming a concave portion corresponding to the outer wall shape of the protruding portion 7, the punching blade 4 disposed in the foamed particle filling tube 6 and driven forward and backward attached to the spindle 3 is used to insert the punching blade into the concave portion. The recessed portion is punched by insertion, and a foamed particle filling port is provided. At this time, it is preferable that the tip of the punching blade 4 disposed at the protruding portion 7 shown in FIG. 3 is once retracted and moved forward again in the cavity direction to punch out the recess.

  In particular, when an annular protrusion is formed and an annular recess corresponding to the shape is formed in the hollow molded body, it is driven back and forth attached to the spindle 3 disposed in the foamed particle filling tube 6. The punching blade 4 is inserted along the inner surface of the foamed particle filling tube that forms the protruding portion in the concave portion, so that the foamed particle filling port is formed inside the annular concave portion.

  FIG. 5 shows a state in which the punching blade is retracted to a predetermined position and the expanded particles are filled from the opened filling port. That is, after the concave portion is punched and the filling port is provided, the punching blade 4 is retracted to a predetermined position where the foamed particles are filled. The foamed particles are filled into the hollow molded body by the pressurized air supplied from the foamed particle supply passage 11 via the pressurized air flow path 12.

  FIG. 6 shows a state in which the position of the punching blade is returned to the position at the time of forming the hollow molded body and the foamed particles are fused with steam after filling the foamed particles. That is, after filling the foamed particles, the punching blade is moved, and the tip of the punching blade 4 is returned to the position of the protruding portion 7 of the foamed particle filling tube 6 (to be in a state when mounted on the mold). Then, steam is supplied into the mold, and the foamed particles are heated and fused, and bonded to a hollow molded body that forms a skin, and then cooled and taken out from the mold to obtain a foam molded body with a skin. .

  The cut piece, which is a part of the recess, cut when the foamed particle filling port is drilled remains in the hollow molded body and is fused with the foamed particles.

  The length of the protrusion from the mold cavity inner surface to the tip of the protrusion (namely, the protrusion height) a is designed in consideration of the thickness (skin thickness) Y of the target hollow molded body, It is preferably about 1 mm to 7 mm. If the protrusion height a of the protrusion is within the above range, the formation of the recess formed in the hollow molded body becomes insufficient, or the soft parison is damaged when forming the recess in the hollow molded body. Therefore, the filling port can be easily drilled, and sufficient strength of the peripheral portion of the filling port can be obtained. From the above viewpoint, the protrusion height is more preferably 1.5 to 6.5 mm. The height of the protrusion is the maximum length up to the tip of the protrusion perpendicular to the mold cavity surface.

  Moreover, it is preferable that the thickness (skin thickness) Y of a hollow molded object is 0.8-6 mm. If it is in the said range, a filling port can be easily incised with the manufacturing apparatus of this invention.

The ratio (a / Y) between the protrusion height a and the thickness (skin thickness) Y of the hollow molded body is:
It is preferable that a / Y = 0.4 to 2.5. When a / Y is within the above range, the hole opening property of the filling port is good, and the foamed particle filling port can be easily opened without breaking the hollow molded body during blow molding.

  The punching length of the punching blade 4 into the hollow molded body (the driving length from the inner surface of the mold) is the height of the protruding portion 7 (projecting portion height), the shape and thickness of the hollow molded body, or the hollow Although it differs depending on the driving direction, the driving position, etc. into the molded body and cannot be determined uniquely, it is preferably approximately 20 mm or more and 80 mm or less with respect to the protruding direction. Furthermore, according to the present invention, the formation of the concave portion makes it possible to form an excellent foamed particle filling port without causing defective punching even when the driving length is 30 mm or less, which is shorter than conventional.

  According to the manufacturing method of the present invention, a good foamed particle filling port can be formed even if the driving length is shortened. For example, the product thickness of the foamed molded product with a skin is a relatively thin plate shape such as 10 mm to 50 mm. Even in the case of a large molded article, a filling port can be formed in the thickness direction from the plane portion to fill the foamed particles, and a good foamed molded article can be obtained efficiently.

  The diameter of the expanded particle filling port provided in the hollow molded body is usually preferably 10 mmΦ or more. From the viewpoint of the filling properties of the expanded particles, it is more preferably 15 to 30 mmΦ.

  Moreover, although the shape of a protrusion part is formed corresponding to the shape of a foaming particle filling port, it is preferable that the shape of a protrusion part is cyclic | annular. When the protruding portion is formed in an annular shape, the parison is easily stretched in the outer wall direction and the inner wall direction of the protruding portion at the annular apex portion, and punching hole processing becomes easier. The outer diameter of the annular protruding portion is preferably 15 to 30 mm, and the inner diameter of the annular portion is a size corresponding to the diameter of the punching blade that operates along the inner surface of the annular portion. It is preferable that the difference between the diameter and the inner diameter is 2 to 6 mm.

It is preferable that the height (projection height from the inner surface of the mold) a (mm) of the projecting portion 7 projected to the inner surface of the mold cavity is a range represented by the following formula (1).
(Equation 1)
Expanded particle filling aperture (mm) × 0.10 ≦ a ≦ Expanded particle filling aperture (mm) × 0.35
... (1)
When a satisfies the above formula, better foamed particle filling holes can be formed.

As for the shape of the punching blade, the shape of the end face of the tip is preferably concave, flat or convex. Furthermore, from the viewpoint of punching ability, if the tip portion is a cylindrical shape recessed in a concave shape, the peripheral edge of the tip portion acts as a cutting blade, so that a more beautiful filling port can be formed.
In addition, when the shape of a punching blade is a column shape, it is preferable that the outer diameter is 10-30 mm. Further, when the shape of the end face of the punching blade is concave, the depth of the concave is preferably 1 to 10 mm.

  The punching process of the recess formed in the hollow molded body provided with the foamed particle filling port is performed immediately after the hollow molded body is molded, but is performed within 30 to 80 seconds after the hollow molded body is molded. It is preferable. If the filling port is formed within the above range and the foamed particles are filled and molded, the hollow molded body is cooled and solidified, and the adhesiveness between the skin, which is the hollow molded body, and the foamed particles can be molded well.

  In the present invention, the resin forming the hollow molded body is a thermoplastic resin. Specifically, low density polyethylene (LDPE), high density polyethylene (HDPE), linear low density polyethylene (LLDPE), polypropylene (propylene homopolymer: h-PP), propylene-ethylene random copolymer (r -PP), polyolefin resins such as propylene-ethylene block copolymer (b-PP); polystyrene (styrene homopolymer: GPPS), high impact polystyrene (HIPS), styrene-methyl methacrylate copolymer (MS) Polystyrene resins such as acrylonitrile-styrene copolymer (AS), polystyrene-modified polyphenylene ether (modified PPE), acrylonitrile-styrene-butadiene copolymer (ABS); polyethylene terephthalate (PET), polybutylene terephthalate ( BT), polyester resins such as polylactic acid (PLA); bisphenol type polycarbonate (PC) polycarbonate-based resin such as, or can be mixtures thereof.

  Among the thermoplastic resins, polyolefin resins are particularly preferable. The polyolefin-based resin is one in which 50 mol% or more of the olefin component structural unit is present in the resin, preferably 60 mol% or more, more preferably 80 mol% or more. Examples of such polyolefin resins include olefin homopolymers, copolymers of olefin components, copolymers of olefin components and polymerizable monomer components copolymerizable with other olefins (the olefin component structural unit). And a mixture of an olefin polymer and another polymer (which satisfies the condition of the abundance of the olefin component structural unit in the mixture). Examples of other polymers to be mixed with the olefin polymer include thermoplastic elastomers such as styrene-butadiene-styrene block copolymers, thermoplastic elastomers, ethylene-propylene rubber, polystyrene resins, and the like.

  In particular, when a polyolefin-based resin is the main component, when a punching blade that is driven back and forth is inserted to provide a filling port in the hollow molded body, the resin has high ductility and the filling port is drilled into the hollow molded body. Tends to be difficult. According to the production method of the present invention, it can be applied when the resin forming the hollow molded body is a thermoplastic resin, and in particular, even if the resin forming the hollow molded body is a polyolefin resin having high ductility, The punching can be easily performed by inserting a punching blade into the concave portion formed in the molded body, and the molding cycle time of the molded body with the skin can be greatly shortened.

  As the polyolefin resin forming the hollow molded body, those having a melting point of 120 to 170 ° C. and a melt flow rate (MFR) of 0.1 to 10 g / 10 min are preferably used from the viewpoint of blow moldability. . The melt flow rate (MFR) is measured based on the test condition M (temperature 230 ° C., load 21.18 N) of JIS K7210 (1999) for polypropylene resin, and JIS K7210 (polyethylene resin). (1999) test condition D (temperature 190 ° C., load 21.18 N).

  Various additives can be added to the thermoplastic resin forming the hollow molded body. Examples of additives include conductivity imparting agents, antioxidants, heat stabilizers, weathering agents, UV inhibitors, flame retardants, inorganic fillers, antibacterial agents, electromagnetic wave shielding agents, gas barrier agents, and antistatic agents. Can be mentioned. These additives are added within the range in which the purpose and effect can be exhibited, and the addition amount is generally 10 parts by weight or less, preferably 5 parts by weight or less, more preferably 3 parts by weight with respect to 100 parts by weight of the thermoplastic resin. Or less.

  The resin constituting the expanded particles used in the present invention is preferably a thermoplastic resin. If the foamed particles are made of a thermoplastic resin, the adhesion between the foamed particles and the hollow molded body forming the skin is improved, and a foamed molded body with a skin having higher strength is obtained. From the above viewpoint, the resin constituting the foamed particles is more preferably the same kind or the same thermoplastic resin as the resin forming the hollow molded body of the skin.

In the present invention, the apparent density of the expanded particles filled in the hollow molded body is not particularly limited, but it is preferable to use generally used expanded particles having an apparent density of 0.018 to 0.3 g / cm ³ . Furthermore, from the viewpoint of easy control of the secondary foaming performance by steam, the apparent density of the foamed particles is more preferably 0.022 to 0.15 g / cm ³ .

  In the present invention, the particle size of the expanded particles filled in the hollow molded body is preferably 1 to 6 mm, and more preferably 2 to 5 mm. If it is in the said range, the filling from a foaming particle filling port will become easy.

  Such expanded particles can be produced by a known method for producing this kind of expanded particles. For example, if necessary, a surfactant is added to a required amount of dispersion medium (usually water) in a pressurized container such as an autoclave to disperse the resin particles, and a foaming agent is injected and stirred under heating. Then, the resin particles are impregnated with the foaming agent, and after a predetermined time, the resin particles impregnated with the foaming agent together with the dispersion medium from the container under the high temperature and high pressure conditions are discharged into a low pressure region (usually under atmospheric pressure) and foamed. It is manufactured by a method for obtaining expanded particles.

  The filling of the foamed particles into the hollow molded body is that the hollow molded body is in the softened state from the foamed particle flow path 11 together with the compressed air flow from the pressurized air flow path 12 before the softened hollow molded body is cooled and solidified. It is preferable to fill the inside with expanded particles. When foamed particles are filled after the hollow molded body is cooled and solidified, the steam supply time is increased when forming foamed molded products with a skin by supplying steam and fusing the foamed particles together. May be required, resulting in a decrease in productivity and insufficient fusion between the inner surface of the hollow molded body, which is the skin, and the foamed particles.

  In the production method of the present invention, the hollow molded body is filled with thermoplastic resin foam particles, and the foam particles are heated and fused with a heating medium to form a foam-molded body with a skin. As the heating medium supplied into the hollow molded body used at this time, steam is usually used, and the steam pressure of the steam is preferably 0.15 MPa to 0.6 MPa (G), more preferably More preferably, the pressure is 18 MPa to 0.5 MPa (G).

  The steam heating conditions for obtaining the foamed particle molded body are as follows: in order to obtain a good foamed particle molded body with good fusion properties between the foamed particles and little shrinkage, the pressure is increased in a relatively short time for the desired molding. It is preferable to reach the pressure and finish the steam heating within a short time. On the other hand, from the viewpoint of the fusion property between the skin and the foamed particle molded body, steam heating is preferably performed until the inner surface of the skin is melted to such an extent that adhesion to the foamed particles is exhibited. The steam thermoforming time is preferably approximately 15 to 60 seconds.

  The heating medium is supplied by inserting a steam supply tubular steam pin into the softened hollow molded body before the hollow molded body that becomes the outer skin is cooled and solidified, and a steam supply hole (steam supply pipe insertion). The foamed particles can be heated and fused by forming a hole or a steam hole) and blowing heated steam from the steam pin into the hollow molded body.

The raw material resins and foamed particles constituting the skin used in Examples and Comparative Examples are shown in Tables 1 and 2 below.
[Raw material resin constituting the skin]

[Foamed particles]

In the present invention, each physical property was measured and evaluated as follows.

[Filling cycle]
This is the time (seconds) required from the step of providing the foamed particle filling port to the hollow molded body until the filling of the foamed particles is completed. That is, the time from when the punching blade provided in the foamed particle filling device starts to operate from the standby position to form the foamed particle filling port until the foamed particle filling port is formed and the filling of the foamed particle is finished. Indicates. In addition, although a filling cycle changes with the volume of a hollow molded object, and the operating conditions of a punching blade, in the Example and the comparative example, the expanded particle molded object is manufactured on the same conditions altogether.

[Evaluation of filling port opening]
The incision state of the expanded particle filling port was visually observed.
Excellent: The appearance of the filling port is beautiful.
Good: When the filling port is opened by the punching blade, the resin forming the hollow molded body is stretched on the inner surface of the molded product, and the appearance is slightly inferior.
Impossible: Incision of filling port not possible

[Fusibility of expanded particles]
As a fusing property evaluation test, 100 mm × 100 mm × (foam not including the skin) that does not include the skin from a total of five locations including the center portion and the four corners (excluding the R portion) of the obtained sheet-like foam-molded article with the skin. Body thickness) was cut out. About 100 or more foamed particles in the fractured surface after breaking the test piece, the state of the cross-section was observed by visual observation, and the fractured with respect to the total of the foamed particles and the foamed particles separated at the interface between the particles. The ratio of expanded particles was determined. Of the measured values at five locations, the lowest value was defined as the fusion rate of the expanded particles, and evaluation was performed according to the following criteria.
Good: Particle fusion rate is 50% or more.
Good: The particle fusion rate is 10% or more and less than 50%.
Impossibility: Particle fusion rate is less than 10%.

[Evaluation of fusion between skin and foam particles]
A 100 mm × 100 mm sample including the epidermis was cut out from a total of five locations including the center part and four corners (excluding the R part) of the obtained plate-like foamed molded article with an epidermis as a test piece for the epidermis fusion property. The skin of the test piece was peeled off, and about 100 or more foamed particles on the peeled surface, the state of the foamed particles on the peeled surface was visually observed, and the foamed particles were broken at the interface between the foamed particles and the skin. The number of foam particles was counted, and the ratio of the foam particles broken to the total of the foam particles broken and the foam particles peeled at the interface between the foam particles and the skin was determined. The lowest value among the five measured values was defined as the fusion rate between the foamed particles and the skin, and evaluated according to the following criteria.
Good: The skin fusion rate is 50% or more.
Good: Skin fusion rate is 10% or more and less than 50%.
Impossibility: The skin fusion rate is less than 10%.

Example 1
A mold for forming a hollow molded body by blow-molding a soft parison formed by extruding a thermoplastic resin melt in a mold cavity, and a tip portion of a connecting part of a foamed particle-filled tube to the mold A punching blade is attached to the tip of a spindle that is driven back and forth by a cylinder, and the punching blade is attached to the hollow molded body from the tip. A foamed molded product with a skin was obtained by the method described below using an apparatus for producing a foamed molded product with a skin having a foamed particle filling device (total length: 400 mm) provided so as to protrude toward the surface.

  To an extruder with an inner diameter of 120 mm, polypropylene resin (manufactured by Nippon Polypro Co., Ltd., trade name: Novatec, grade: EC9EV, melt flow rate (MFR): 0.4 g / 10 min (measuring conditions: 230 ° C., 2. 18N)) was supplied, heated and kneaded at 220 ° C. to obtain a resin melt, and filled in an accumulator attached to an extruder and prepared at 220 ° C. The resin melt was then extruded from the die to form a softened parison. The parison was placed in a split flat plate mold having the dimensions shown in Table 3 (vertical: 1030 mm × horizontal: 720 mm × thickness: 40 mm) arranged directly under the die, and the mold was clamped. Thereafter, 0.50 MPa of pressurized air was blown into the parison through the blow gas introduction hole, and at the same time, the pressure between the outer surface of the parison and the mold was reduced, and the skin thickness reflecting the shape of the mold cavity was 5 mm. A hollow molded body was formed.

  As the manufacturing apparatus, a protruding portion (projecting portion height: a = 4 mm, an outer diameter of 22 mmΦ, an inner diameter of 18 mmΦ made of annular steel) protruding into a mold cavity having the above-described configuration, An apparatus for producing a foam-molded article with a skin provided with a cylindrical punching blade of 17.8 mmΦ that is driven into the mold cavity was used. The tip of the punching blade was concave, and the depth of the concave shape was 4 mm.

  When forming a hollow molded body by blow-molding the softened parison, the parison is brought into contact with the protruding portion protruding into the mold cavity to contact the inner surface of the mold cavity of the formed hollow molded body. On the side, a concave portion corresponding to the shape of the protruding portion was formed in the hollow molded body in the inner direction of the hollow molded body. The hollow molded body was molded at a mold temperature of 70 ° C.

  The protrusions were arranged at two locations on one plane formed by the length x width of the flat plate of the mold. Therefore, the expanded particle filling port is formed only on one surface formed by the length × width of the flat plate. The punching hole for punching holes in the filling port is inserted so as to protrude in the thickness direction of the flat foam molded body. At the time of blow molding, the tip of the punching blade was disposed at the same position as the tip of the protruding portion with respect to the tip of the connecting portion of the foamed particle filling apparatus attached to the mold. (The time from mold clamping to the start of punching blade opening operation is shown in the table as blow molding time).

  Next, a cylindrical punching blade attached to the spindle is protruded from the tip end (the insertion length of the punching blade is 30 mm), the concave portion formed in the hollow molded body is punched, and a foam particle filling port (caliber 18 mmΦ) Was drilled. The punching blade has a cylindrical tip portion recessed in a concave shape, and its peripheral edge is formed in a blade shape.

Next, the punching blade is retracted to a predetermined position in the filling device, and the apparent density of 0. 0 is applied from the foamed particle supply channel to the softened hollow molded body by the pressurized air supplied from the pressurized air channel. 045 g / cm ³ of polypropylene resin expanded particles were filled.

  When the foamed particles are filled after forming the hollow molded body, a steam supply hole is formed in the hollow molded body, a steam pipe is inserted, and the inside of the hollow molded body is inserted through a slit provided in the peripheral wall portion of the steam pipe. While adjusting the pressure, the gas in the hollow molded body was exhausted to fill the expanded particles.

After filling the expanded particles, the steam having the steam pressure shown in Table 2 was supplied for 8 seconds from the other steam tube while sucking the steam from one of the steam tubes inserted into the hollow molded body. Next, the steam having the steam pressure shown in Table 2 was supplied for 8 seconds from the steam pipe that was sucking the other steam while sucking from the steam pipe that was supplying the steam (preliminary molding). Next, steam of the steam pressure shown in Table 2 was supplied from all the steam pipes for 10 seconds to heat and fuse the foamed particles, and the inner surface of the hollow molded body and the foamed particles were bonded together (main molding). After the molding, the mold was cooled, and then the mold was opened to obtain the desired foamed article with skin. The properties of the obtained foamed molded product are shown in Table 3.

Example 2
Except that the thickness of the skin was 4 mm and the production conditions shown in Table 3 were used, the same procedure as in Example 1 was performed to obtain a foamed product with skin. The thinner the skin thickness, the better the filling port was formed, and the filling cycle was shortened. Table 3 shows the production conditions of the foamed molded product and the characteristics of the foamed molded product.

Example 3
Except that the thickness of the skin was 3 mm and the production conditions shown in Table 3 were used, the same procedure as in Example 1 was carried out to obtain a foamed product with skin. The thinner the skin thickness, the better the filling port was formed. Also, the filling cycle was shortened. Table 3 shows the production conditions of the foamed molded product and the characteristics of the foamed molded product.

Example 4
The same procedure as in Example 1 was carried out except that the length of the projecting portion of the foamed particle-filled tube connected to the mold in the production apparatus was 6 mm, and the production conditions shown in Table 3 were used. As a result, a foamed molded article with a skin was obtained. Compared to Example 1, the formation state of the filling port was improved, and the filling cycle was shortened. Table 3 shows the properties of the foamed molded product.

Example 5
Except for the manufacturing conditions shown in Table 3 except that the height of the projecting portion projecting from the die cavity surface at the tip of the connecting portion of the foamed particle-filled tube in the manufacturing apparatus to the mold was 2 mm. As a result, a foamed molded article with a skin was obtained. Table 3 shows the properties of the foamed molded product.

Example 6
A foam molded body with a skin was obtained by carrying out the same apparatus as used in Example 1 except that the mold thickness was 30 mm, the insertion length of the punching blade was 20 mm, and the production conditions shown in Table 4 were used. Compared to Example 1, the filling cycle is shortened as the product thickness is reduced. The properties of the foamed molded product are shown in Table 4.

Example 7
Except that the thickness of the skin was 4 mm and the production conditions shown in Table 4 were used, the same procedure as in Example 6 was carried out to obtain a foamed product with skin. Table 4 shows the characteristics of the foamed molded product.

Example 8
Except that the skin thickness was 3 mm and the production conditions shown in Table 4 were used, the same procedure as in Example 6 was carried out to obtain a foamed product with skin. Table 4 shows the characteristics of the foamed molded product.

Example 9
A foamed molded article with a skin was obtained in the same manner as in Example 8 except that the height of the protruding portion in the production apparatus was 2 mm, the skin thickness was 4 mm, and the production conditions shown in Table 4 were used. The filling cycle was slightly longer than in Example 8 due to the thick skin. Table 4 shows the characteristics of the foamed molded product.

Example 10
A foamed molded article with a skin was obtained in the same manner as in Example 9 except that the height of the protruding portion in the production apparatus was 2 mm, the skin thickness was 2 mm, and the production conditions shown in Table 4 were used. Compared with Example 9, since the skin thickness was thin, the formation state of the filling port was improved. Also, the filling cycle was shortened. Table 4 shows the characteristics of the foamed molded product.

Example 11
A foamed molded article with a skin was obtained in the same manner as in Example 9 except that the height of the protruding portion in the production apparatus was 2 mm, the skin thickness was 1 mm, and the production conditions shown in Table 4 were used. Compared with Example 9, since the skin thickness was thin, the formation state of the filling port was improved. Also, the filling cycle was shortened. Table 4 shows the characteristics of the foamed molded product.

Example 12
A foamed molded article with a skin was obtained in the same manner as in Example 1 except that the raw material resin forming the skin was PE1 shown in Table 1, the foamed particles were PE shown in Table 2, and the production conditions shown in Table 5 were used. Table 5 shows the properties of the foamed molded product.

Example 13
Except that the thickness of the skin was 4 mm and the production conditions shown in Table 5 were used, the same procedure as in Example 12 was carried out to obtain a foamed product with skin. The formation state of the filling port was improved as the skin became thinner. Table 5 shows the properties of the foamed molded product.

Example 14
Except that the skin thickness was 3 mm and the production conditions shown in Table 5 were used, the same procedure as in Example 12 was carried out to obtain a foamed product with skin. The formation state of the filling port was improved as the skin became thinner. Table 5 shows the properties of the foamed molded product.

Comparative Example 1
The same procedure as in Example 1 was carried out except that a foamed molded product production apparatus with a skin having no protrusions into the mold was used. However, the filling port could not be opened, and the expanded particles could not be filled into the hollow molded body.

Comparative Example 2
Using a filling device equipped with a conventional rotary cutter, the filling port was opened by being inserted into the hollow molded body while rotating the cutter. Compared to Example 1, the overall length of the apparatus was large, and it took time to form the filling port, and the filling cycle became longer, resulting in a decrease in productivity. The properties of the obtained foamed molded product are shown in Table 3.

Comparative Example 3
The same procedure as in Example 6 was performed, except that a foamed molded product manufacturing apparatus with a skin that did not have a protrusion into the mold was used. However, the filling port could not be opened, and the expanded particles could not be filled into the hollow molded body.

Comparative Example 4
Using a filling device equipped with a conventional rotary cutter, the filling port was opened by being inserted into the hollow molded body while rotating the cutter. Compared to Example 6, the overall length of the apparatus was large, and it took time to form the filling port, and the filling cycle became longer, resulting in decreased productivity. Table 4 shows the properties of the obtained foamed molded article.

Comparative Example 5
The same procedure as in Example 12 was performed, except that a foamed molded article production apparatus with a skin that did not have a protrusion into the mold was used. However, the filling port could not be opened, and the expanded particles could not be filled into the hollow molded body.

Comparative Example 6
Using a filling device equipped with a conventional rotary cutter, the filling port was opened by being inserted into the hollow molded body while rotating the cutter. Compared with Example 12, it took time to form the filling port, and the molding cycle became longer and the productivity was lowered. Table 5 shows the properties of the obtained foamed molded article.

DESCRIPTION OF SYMBOLS 1 Expanded particle filling apparatus 2 Steam pin 3 Spindle 4 Punching blade 41 Cutting edge part 5 Piston cylinder 6 Expanded particle filling pipe 7 Projection part 11 Expanded particle path 12 Pressurized air flow path A Mold cavity B Mold C Hollow molded body ( Epidermis)
C1 Concavity D Expanded particle

Claims (6)

A thermoplastic resin melt is extruded to form a soft parison, and the parison is blow-molded in a mold cavity to form a hollow molded body, and then the foamed thermoplastic resin particles in the molded body are formed. A foamed molded article with a skin, wherein the foamed particles are filled from the filling port, the heated particles are supplied into the hollow molded body, and the foamed particles are heated and fused. There,
When the parison is blow-molded, the parison is brought into contact with an annular projecting portion formed to project from the mold cavity surface in the inner direction of the mold cavity, so that the hollow molded body has the shape of the projecting portion. A method for producing a foamed molded article with a skin, wherein a corresponding annular recess is formed, and a punching blade is inserted along the inner surface of the projecting portion to form the filling port inside the annular recess. The projecting portion is formed by projecting a tip of a foam particle filling tube for filling foam particles from the mold cavity surface, and the punching blade fills the foam particle along the inner surface of the foam particle filling tube. 2. The method for producing a foamed molded article with a skin according to claim 1, wherein the foamed molded article is provided so as to be able to be inserted from a pipe into the hollow molded article . The method for producing a foamed article with a skin according to claim 1 or 2, wherein the punching blade has a cylindrical shape, and an end surface of the tip of the punching blade is recessed in a concave shape. Method for manufacturing a skin-integrated foamed molded article according to any one of claims 1 to 3, the height a of the protrusion from the mold cavity surface, characterized in 1~7mm der Rukoto. Thermoplastic resin The production method of the skin-integrated foamed molded article according to any one of claims 1 to 4, wherein Rukoto such a polyolefin resin constituting the thermoplastic resin melt. A mold in which a soft parison formed by extruding a thermoplastic resin melt is blow-molded in a mold cavity to form a hollow molded body, a foam particle-filled tube filled with foam particles, and the foam particles An apparatus for producing a foamed molded article with a skin having a punching blade for forming a filling port, wherein the foamed particle filling tube projects from the mold cavity surface to the inside of the cavity at the tip of the mounting part to the mold is not mounted on the mold, the Rukoto ball striking punching blade is provided so as to be projected toward the mold cavity from the distal end of the expanded beads filled tube along the inner surface of the expanded beads filled tube Table unpeeled foam molding producing apparatus shall be the features.

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