JP2000210967A - Manufacture of foamed molding with skin and foamed molding with skin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve fusion bondability of foamed pieces with each other by covering at least a part of a surface of a thermoplastic resin foamed piece molding having communicating air gaps with a hollow molding made of a thermoplastic resin to form a foamed molding with a skin, and specifying a void fraction of the molding. SOLUTION: The method for manufacturing a foamed molding with a skin for use in an interior finishing material or the like of an automobile comprises the steps of filling thermoplastic resin foamed pieces 1 in a hollow molding made of a thermoplastic resin, heating the pieces 1 by a heating medium, and fusion bonding the pieces to each other. The pieces 1 are formed in shape so that a porosity when closet packing is 45% or above. As the used piece 1, cylindrical foamed particles or the like made of a thermoplastic resin as a base material resin is preferably used. As the particles, particles of a shape having a hollow hole communicating with the exterior and a circular shape or a polygonal shape in an outer peripheral shape and a hollow hole shape of a vertical section in a hole direction or the like are used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a foamed article with a skin and a foamed article with a skin.

[0002]

2. Description of the Prior Art A hollow molded article obtained by blow molding or the like is filled with expanded thermoplastic resin particles and heated by steam or the like to fuse the expanded particles to each other. The foam molded body with skin is
It is widely used in various fields such as box-shaped containers, building panels, cushioning materials, and automobile interior materials. In the case of producing such a foamed molded article with a skin, if the hollow molded article has poor steam permeability, it is difficult for the heating steam to sufficiently penetrate between the foamed particles filled in the hollow molded article.

[0003] As a method that can solve such a problem,
A method is proposed in which a steam supply pin is inserted into the foamed particle layer filled in the hollow molded body so that steam penetrates into the foamed particle layer, and the steam supply pin is removed before the foamed particles are fused together. (Tokuko Sho 6
No. 2-19293, Japanese Utility Model Publication No. 62-9073, etc.). However, since generally spherical foamed particles are generally used as the foamed particles, it is difficult for steam to penetrate to the deep portion of the foamed particles filled in the hollow molded body. Wearability,
In the case where the foamed particles and the hollow molded body have a fusion property, there is a problem that only a foamed molded article with a skin having poor fusion property can be obtained. In particular, when an attempt is made to obtain a foamed molded article having a complex structure or a thick skin, there is a problem that the above-mentioned defective fusion is remarkable.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and is intended to provide a method for producing a foamed molded article with a skin having excellent fusion property between foam pieces, and an excellent foamed molding with a skin. The purpose is to provide the body.

[0005]

That is, in the method for producing a foamed molded article with a skin according to the present invention, a thermoplastic resin foam piece is filled in a hollow molded article made of a thermoplastic resin, and the foam piece is heated. What is claimed is: 1. A method for producing a foamed molded article having a skin, wherein the foamed piece is fused by heating with a medium, wherein the foamed piece has a shape having a void fraction of 45% or more at the time of close packing. I do. In the present invention, the thermoplastic resin foam pieces to be filled in the hollow molded body made of a thermoplastic resin are preferably tubular thermoplastic resin foam particles.

The foamed molded article with a skin according to the present invention comprises a skin formed by covering at least a part of the surface of a molded piece of a thermoplastic resin foam having communicating voids with a hollow molded article made of a thermoplastic resin. A foam molded article with a foam, wherein the porosity of the foam piece molded article is 5% or more.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The base resin of the thermoplastic resin foam piece used in the present invention includes vinyl chloride resins such as polyvinyl chloride, polystyrene resins such as polystyrene, polyethylene resins and polypropylene resins. Examples include polyolefin resins, acrylic resins such as polymethyl methacrylate, and polycarbonate resins.
Examples of the polyethylene-based resin and polypropylene-based resin, for example, low-density polyethylene, medium-density polyethylene,
High-density polyethylene, linear low-density polyethylene, linear ultra-low-density polyethylene, ethylene-propylene block copolymer, ethylene-propylene random copolymer,
Ionomer system in which the molecules of ethylene-butene block copolymer, ethylene-butene random copolymer, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, and ethylene-methacrylic acid copolymer are crosslinked with metal ions. Resin, propylene homopolymer, propylene-ethylene random copolymer, propylene-butene random copolymer, propylene-ethylene block copolymer, propylene-butene block copolymer, polybutene, polypentene, propylene-ethylene-butene ternary Copolymers, propylene-acrylic acid copolymers, propylene-maleic anhydride copolymers and the like can be mentioned. In addition, a copolymer of an olefin monomer such as ethylene, propylene, butene, and pentene and a monomer such as styrene copolymerizable with the olefin monomer can also be used.

[0008] Among the above thermoplastic resins, polyolefin resins having good buffering property and compressive strain recovery property are preferable. Among them, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene,
Polyethylene resins such as linear ultra-low density polyethylene, and polypropylene, polybutene, propylene-ethylene copolymer, propylene-butene copolymer, propylene-ethylene-butene terpolymer are preferred, and propylene-ethylene random is particularly preferred. A copolymer, a propylene-butene random copolymer, a propylene-ethylene-butene terpolymer, and a linear low-density polyethylene are preferred.

The above-mentioned polyolefin resin may be cross-linked by peroxide or radiation or may be used without cross-linking, but is preferably a non-cross-linked resin which has a simple production process and is recyclable.

In the present invention, the thermoplastic resin foam pieces to be filled in the hollow molded article have a porosity of 45% or more at the time of closest packing, preferably 50 to 70%. . If the porosity is less than 45%, the permeability of the heating medium is poor, and only the foamed molded article with skin having poor fusion between the foam pieces can be obtained. One having the above shape can be used alone or in combination of two or more. The porosity at the time of the close-packing is that a fixed amount of the thermoplastic resin foam piece is filled into a graduated container such as a measuring cylinder, and the container is vibrated up and down without compressing the thermoplastic resin foam piece. When the volume of the foam piece was minimized, the volume of the foam piece of a certain amount obtained from the scale of the container was set to an apparent volume: A (cm ³ ), and then the apparent volume was measured. Subsequent foam pieces were immersed in alcohol in a graduated container containing alcohol, and a certain amount of the true volume of foam pieces: B (cm ³ ) was determined from the increase from the volume of alcohol alone, The apparent volume: A and the true volume: B are obtained from the following formula.

[0011]

## EQU1 ## Space ratio (%) = {(AB) / A} × 100

The heating medium for fusing the foam pieces in the method of the present invention includes steam, hot air and the like.
Industrially advantageous steam is preferred.

In the present invention, the thermoplastic resin foam pieces used for molding include cylindrical foam particles having the above-mentioned thermoplastic resin as a base resin, and a length between L: D and D: D. Columnar foamed particles having a relationship of L / D ≧ 4 and foamed particles having projections on the surface are preferable.

Hereinafter, a case where foamed thermoplastic resin particles are used as the foamed thermoplastic resin pieces will be described as an example. However, unless otherwise specified, chip-shaped materials and pulverized materials are used instead of the thermoplastic resin foamed particles. The same technique can be applied to the case of using such a method.

The cylindrical foamed particles have a shape having a hollow hole communicating with the outside (hereinafter, the direction in which the hollow hole communicates with the outside is referred to as "hole direction"), and (a) the hole direction. The outer peripheral shape and the hollow hole shape in a vertical cross section (hereinafter, this cross section is referred to as “vertical cross section”) are both circular, and (b) the outer peripheral shape and the hollow hole shape in the vertical cross section are both polygonal , (C) one of the outer peripheral shape and the hollow hole shape in the vertical cross section is circular and the other is polygonal, and (d) the one having the cross sectional shape as described in (a) to (c) above. (E) perpendicularly to the hole direction, having a cross-sectional shape as described in (a) to (d) above, provided with projections in any cross section, (f) in a certain vertical cross section Is as described in (a) to (d) above. Has a surface shape, in another vertical cross-section can be exemplified such as those having such cross-sectional shape of the protrusion is provided (a) ~ (d).

Of the expanded particles shown in FIGS. 1A to 1S, those corresponding to the above (a) correspond to the expanded particles of (A), and those corresponding to (b) correspond to (a). ) ~ (D)
The foamed particles of (c) correspond to (c),
The expanded particles of (f) correspond to (d) and (g) as those corresponding to (d), and the expanded particles of (q) to (s) as corresponding to (e), What corresponds to (f) includes the foamed particles (c) and (so).
In FIG. 1, 1 indicates expanded particles, P indicates a hollow hole, and e indicates a protrusion.

The expanded particles shown in FIG. 1 are merely examples of cylindrical expanded particles that can be used in the present invention. In addition, the outer peripheral shape and hollow hole shape in the vertical cross section are other than elliptical and regular polygon. Polygonal, foamed particles are partly constricted along the hole direction, foamed particles are twisted along the hole direction, hollow holes are shifted from the center in the vertical cross section, etc. Any shape can be used as long as it is cylindrical expanded particles. In the present invention, tubular foamed particles having a shape in which a part of the tubular foamed particles is cut so as to have a C-shaped vertical cross section are also included in the tubular foamed particles.

The above-mentioned tubular expanded particles have a ratio of a maximum outer diameter D in a vertical cross section to a maximum length L in the hole direction.
It is preferable that L / D is 0.2 to 5.0, especially 0.5 to 2.0. L / D of the cylindrical expanded particles is 0.2 to 5.
When it is in the range of 0, it is preferable because the filling property of the foamed particles into the hollow molded article becomes good and the fusion property between the foamed particles becomes good. The maximum outer diameter D is shown in FIG.
As shown in (a), (g), (g), and (se), this is the maximum value of the distance between two parallel tangents that are in contact with the outer periphery in the vertical cross section, and can be measured with a caliper. Also, L has the maximum length as shown in FIGS. 1A and 1K, and can be measured with a caliper.

As shown in FIGS. 1 (a) to 1 (c), the foamed particles having no projection e, such as the foamed particles shown in FIGS. This is preferable because it hardly occurs and uniform filling can be easily performed inside the hollow molded body. Further, those having both a circular outer peripheral shape and a hollow hole shape in a vertical cross section, such as the foamed particles (a), (g), and (h), are preferable because the production of the foamed particles is relatively easy.

In the present invention, besides the above-mentioned tubular foamed particles, foamed particles having only protrusions without hollow holes and columnar foamed particles can be used. In the case of columnar foamed particles, as shown in FIG. Outer diameter in vertical section perpendicular to: D and length:
It is necessary that the relationship of L / D ≧ 4 is satisfied with L, and it is particularly preferable that 7 ≧ L / D ≧ 4. The columnar foamed particles are not limited to the columnar ones shown in FIG. 2, but may be polygonal ones.
If the value of L / D is less than 4, the porosity at the time of closest packing is 4
Since 5% or more may not be obtained, the fusion property between the expanded particles is inferior, which is not preferable. In the case of foamed particles having no hollow holes and having protrusions, as shown in FIGS. 4A and 4B, even in a cross section perpendicular to the direction of the length L of the foamed particles, a protrusion e is formed on the outer periphery. Are preferably formed in such a manner that the particles have three or four protrusions in the cross section in view of the production stability of the expanded particles, and the length: L and the maximum outer diameter: Ratio with D: L / D
Is preferably 0.5 to 2.0 in view of the filling property when the expanded particles are filled into the hollow molded article.

As described above, in the present invention, various types of cylindrical foamed particles as shown in FIG.
Columnar foamed particles of / D ≧ 4 and foamed particles having protrusions as shown in FIG. 4 can be used. In particular, when the base resin of the thermoplastic foamed particles is an olefin resin, the thermoplastic resin hollow is used. It is difficult to fuse the foamed particles together inside the molded body. For this reason, the heating medium can penetrate to the deep part and can be reliably fused.
A tubular expanded particle as shown in (e), particularly a cylindrical expanded particle, is preferable. The cylindrical foamed particles as shown in FIGS. 1A and 1E and the cylindrical foamed particles as shown in FIG. 2 have a substantially circular shape even if the outer peripheral shape of the vertical cross section is not a true circle. You only need to have it.

In particular, the cylindrical expanded particles preferably have an average particle weight of 1 to 50 mg, and more preferably have an average particle weight of 1 to 10 mg. It is difficult to produce foamed particles having an average particle weight of less than 1 mg, and if the average particle weight is more than 50 mg, the filling property of the hollow molded article during molding tends to be poor. Although it depends on the average particle weight, for example, in the case of cylindrical expanded particles having an average particle weight of 1 to 10 mg, the minimum diameter of the hollow hole in an arbitrary vertical cross section is d.
_MIN, at the same time that the minimum diameter of the outer circumference was set to D _{MI N} in vertical section, d _MIN is 0.5mm or more, and d _MIN / D _MIN
Is preferably 0.30 to 0.90, more preferably d _MIN is 1.0 mm or more, and d _MIN / D
The value of _MIN is 0.40 to 0.85. Note that the upper limit of d _MIN is preferably 20 mm, particularly preferably 10 mm or less.

When molded using cylindrical foamed particles satisfying the above relationship between d _MIN and D _MIN , it is possible to obtain a foamed molded article with a skin having a small shrinkage and a better fusion property between particles. Can be. The value of d _MIN / D _MIN is 0.
The foamed particles having a particle size exceeding 90 have a problem that the production itself is difficult and tend to be a foamed molded article with a skin lacking in dimensional stability.

When there are a plurality of hollow holes as shown in (g), (h) and (so) in FIG. 1, all of the hollow holes, (g) to (so), etc. If the protrusion is provided on the outer periphery as in the shape excluding the protrusion,
Preferably, the above relationship is satisfied.

In the method of the present invention, since the above-mentioned expanded particles are used as the foam pieces, even if the hollow molded body does not have the permeability of the heating medium, the deep layer portion of the foam pieces filled in the hollow molded body can be obtained. Until the heating medium penetrates between the foam pieces and arrives. As a result, the filled foam piece located near the inside of the hollow molded article is sufficiently heated, and the foam piece near the inside of the hollow molded article is heated. In the case where the spaces between the foam pieces and the hollow molded body are reliably fused together, and the inner surface side of the hollow molded body is made of a material having a fusibility with the foam piece, the fusion between the foam pieces and the hollow molded body is ensured.

The foamed particles are prepared by dispersing thermoplastic resin particles and a foaming agent in a dispersion medium in a closed container and heating the mixture with stirring to impregnate the resin particles with the foaming agent. The particles and the dispersion medium can be obtained by a method in which the resin particles are released under a lower pressure (usually, atmospheric pressure) from the container and the resin particles are foamed.

The thermoplastic resin particles used for the production of foamed particles can be obtained by, for example, melting and kneading the base resin in an extruder, extruding it from a die into a strand, cooling it, and cutting it into appropriate lengths. Although it is possible, when melt-kneading the base resin in the extruder, if necessary, an inorganic substance such as talc, calcium carbonate, borax, aluminum hydroxide, zinc borate, etc. is added and melt-kneaded with the resin, and the resin particles are mixed. These inorganic substances may be added to the mixture. Also, depending on the application and purpose,
Coloring can also be performed by adding a coloring pigment or dye such as black, gray, brown, yellow, red, pink, green, and blue. When the above-mentioned inorganic substances, coloring pigments, dyes and the like are added to the resin particles, a masterbatch method is usually adopted in consideration of their dispersibility. The amount of the inorganic substance, the coloring pigment, and the dye is usually 0.001 to 5 parts by weight per 100 parts by weight of the resin particles. When an inorganic substance is contained in the resin particles, the expansion ratio of the expanded particles can be improved, and the diameter of the cells can be adjusted to 50 to 350 μm, which is preferable in terms of secondary expandability and dimensional stability.

When a molten resin is extruded from a die, a die having a resin extrusion port having a shape substantially similar to the cross-sectional shape of the foamed particles to be obtained (for example, in the case of obtaining cylindrical foamed particles, a vertical By using a die having a resin extrusion port having a substantially similar cross-sectional shape, resin particles having a similar shape to the foamed particles having the desired shape can be obtained. As described above, foaming is performed using such resin particles. If it is carried out, it is possible to obtain foamed particles having a desired shape.

The dispersion medium used for producing the foamed particles may be any one which does not dissolve the resin particles, and includes, for example, water, ethylene glycol, glycerin, methanol, ethanol and the like, but water is usually used. Further, as the blowing agent, usually, propane, butane, hexane, cyclobutane, cyclohexane, trichlorofluoromethane, dichlorofluoromethane, chlorofluoromethane,
Volatilization of trifluoromethane, 1,1,1,2-tetrafluoroethane, 1-chloro-1,1-difluoroethane, 1,1-difluoroethane, 1-chloro-1,2,2,2-tetrafluoroethane, etc. A foaming agent and an inorganic gas-based foaming agent such as nitrogen, carbon dioxide, argon, and air are used. It is also possible to use a mixed foaming agent of a volatile foaming agent and an inorganic gas-based foaming agent. Among these, inexpensive inorganic gas-based foaming agents which do not cause a risk of destruction of the ozone layer are preferable, and nitrogen, carbon dioxide, and air are particularly preferable. The amount of the foaming agent used other than nitrogen and air is usually 2 to 50 parts by weight per 100 parts by weight of the resin particles. In the case of nitrogen and air, the amount used is within the pressure range for press-fitting into a closed container. It is preferable to add so as to be 5 to 60 kgf / cm ² G. The amount of the foaming agent used is appropriately adjusted according to the expansion ratio of the foamed particles to be obtained.

When the resin particles and the foaming agent are dispersed in a dispersion medium and heated, a fusion inhibitor may be added to the dispersion medium in order to prevent fusion between the resin particles. As the anti-fusing agent, any inorganic or organic one can be used as long as it does not dissolve in the dispersion medium and does not melt by heating. In general, an inorganic one is preferable. Powders such as kaolin, talc, mica, aluminum oxide, titanium oxide, and aluminum hydroxide are suitable as the inorganic anti-fusion agent. The anti-fusing agent has an average particle size of 0.001 to 10
It is preferably 0 μm, particularly preferably 0.01 to 30 μm. The anti-fusing agent is usually used in an amount of 0.0
It is preferable to add 1 to 10 parts by weight. An anionic surfactant such as sodium dodecylbenzenesulfonate and sodium oleate can be used in combination as a dispersing aid. It is preferable that the dispersing agent is usually added to the dispersion medium in an amount of 0.001 to 5 parts by weight per 100 parts by weight of the resin particles.

The foamed particles have a larger overall size than the resin particles before foaming.
The values of _MIN / D _MIN and L / D and the corresponding values of d _MIN ′ / D _MIN ′ and L ′ / D ′ of the _unfoamed resin particles are almost the same, _MIN ´ / D _MIN
As long as the values of 'and L' / D 'satisfy the above conditions, the values of d _MIN / D _MIN and L / D of the expanded particles also generally satisfy the above conditions.

As means for obtaining foam pieces such as chips and pulverized products other than foamed thermoplastic resin particles used in the present invention, for the chip-shaped materials, thermoplastic resin is extruded into a rod shape from the tip of an extruder. By slicing with a cutter blade immediately after extrusion foaming, a chip-shaped foam can be obtained. The pulverized product can be obtained by pulverizing an existing foamed particle molded article, foamed sheet or the like with a pulverizer.

In the present invention, the base resin of the hollow molded article made of a thermoplastic resin is the same as the base resin of the thermoplastic resin foam piece described above.

In the present invention, as the hollow molded article, a molded article having a desired shape by a method such as injection molding or blow molding can be used. For example, in order to obtain a hollow molded body by blow molding, the parison of the thermoplastic resin is lowered from above the mold, the parison is sandwiched by the mold, air is blown into the parison from the air blow pin to inflate the parison, and The hollow molded body is formed by sucking the parison through the suction hole provided in the mold and bringing the parison into close contact with the inner surface of the mold. Also, it is not necessary to mold the molded article in advance, and the hollow molded article and the foamed molded article with the skin may be manufactured by the same mold.For example, after molding a hollow molded article of a thermoplastic resin, the foam piece is hollowed out. The molded article may be filled into a foamed article with a skin. The hollow molded body is not limited to an unfoamed or foamed single-layer structure, but may be a multilayered structure having an unfoamed layer, a foamed layer, and the like. The inner surface of the hollow molded body may be made of a material having a fusibility with the foam piece or a material having no fusibility. When a molded body is required, it can be formed of a material having fusibility, because a foamed molded article with a skin excellent in fusibility between a foam piece molded body and a hollow molded body can be obtained. preferable. The thickness of the hollow molded body is preferably 1 to 5 mm. If the thickness of the hollow molded article is less than 1 mm, the shape retention of the hollow molded article may be deteriorated. If the thickness exceeds 5 mm, the weight of the foamed molded article with skin is not preferable. As the shape of the hollow molded body, for example, a penetrating cylindrical shape,
A shape such as a cylindrical shape with a bottom, a hollow plate shape, or a box-shaped container shape can be used.

The material having the fusion property between the thermoplastic resin foam particles and the hollow molded body made of the thermoplastic resin differs depending on the difference of the base resin of the thermoplastic resin foam particles. When the base resin of the thermoplastic resin expanded particles is, for example, a polypropylene resin, the base resin of the hollow molded body made of the thermoplastic resin is also a polypropylene resin or a polypropylene thermoplastic elastomer, and the base of the expanded particles. When the resin is a polyethylene-based resin, the base resin of the hollow molded body made of a thermoplastic resin is also preferably a polyethylene-based resin, but is not limited thereto as long as the resin has fusibility with the foamed particles. .

As the material of the above-mentioned hollow molded article having a fusion property with the expanded thermoplastic resin particles, if a material having a melting point lower than the melting point of the base resin of the expanded thermoplastic resin particles to be used is selected, This is preferable because the fusion property with the hollow molded body is further improved.

In the case where the hollow molded article has a multilayer structure, the material constituting the surface side (the side not in contact with the thermoplastic resin foam piece) may be the above-mentioned material having a fusion property with the thermoplastic resin foam piece. In addition, a material such as polyvinyl chloride or the like, which does not have a fusion property with a thermoplastic resin foam piece, or a polyester resin can be used.

In order to obtain a high-strength, high-rigidity foamed molded article with a skin, the material of the hollow molded article (at least the material on the inner surface side in the case of a multilayer structure) and the base resin of the foam piece are used. It is preferable to select materials having mutual heat-fusion properties as described above. In particular, when the foamed molded article with a skin of the present invention is used for a vehicle such as an automobile interior material or a bumper, heat resistance, rigidity, energy absorption,
In consideration of recyclability and the like, it is preferable to select a polypropylene resin for both the material of the hollow molded article and the base resin of the foam piece. Further, when the foamed molded article with a skin of the present invention is used for bedding, furniture, etc., in consideration of cushioning properties and the like, a polyethylene resin as a base resin of the foam piece,
In particular, linear low-density polyethylene is preferable, and it is preferable to select a polyethylene-based resin having heat-fusibility with the material of the hollow molded body (or the material on the inner surface side of the hollow molded body).

In the foam molded article with a skin according to the present invention, the foam pieces to be filled into the hollow molded article are, as described above, in order to obtain a foam piece molded article having communicating voids, as described above. It is necessary that the porosity has a shape of 45% or more, but more preferably cylindrical foamed particles, particularly cylindrical foamed particles. Since the foam pieces are used, the foam pieces have excellent fusion property with each other, and when the inner layer side of the hollow molded body has a fusion with the foam pieces, the fusion property between the foam piece molded article and the hollow molded body is improved. It is an excellent foam molded article with a skin. In the foamed molded article with a skin of the present invention, the porosity of the foam piece molded article having voids communicating with each other is preferably 5% or more. Further, a porosity of 5 to 75% is preferable,
A porosity of 45% is preferred. It is not preferable that the foam piece having a porosity of less than 5% cannot be used as a gas-permeable heat insulating panel, a sound-absorbing panel, a sound-absorbing panel, or a filtering material, a water-permeable material, or a water-retaining material. The porosity (%) of the above-mentioned foam piece molded product is determined by measuring the outer dimensions (2
5 mm x 25 mm x 100 mm)
(Cm ³ ), where b (cm ³ ) is the true volume of the sample obtained from the amount of increase in the scale when the sample is submerged in alcohol in a graduated container containing alcohol, and is obtained from the following equation. Value.

[0040]

## EQU2 ## Porosity (%) = {1- (b / a)} × 100

As a method for obtaining a foamed body with a skin of the present invention, for example, a hollow molded body is obtained by a blow molding machine, the hollow molded body is mounted on a mold, and the hollow molded body is mounted on a mold. A method of obtaining a molded body with a skin by filling the inside of the body and molding, a method of molding a hollow molded body and a molding of a foam with a skin with a mold also having a function of molding the hollow molded body, a hollow molded body When the foam has a rigidity, a method of obtaining a foam with a skin by filling a foam piece inside the hollow molded body without using a mold is used.

The mold for obtaining the foamed molded article with the skin is, for example, a combination mold composed of a concave mold and a convex mold, and has a space for indirectly cooling the foamed molded article with the skin by cooling the mold surface. It has a feeder for filling the foam piece into the hollow molded body, a pin having a large number of slit or circular holes for supplying a heating medium and sucking air or the heating medium.
In particular, when the mold also has a function of molding a hollow molded body, a hole is provided in the mold for inserting an air blow pin for expanding the parison from below the mold.

Further, in the present invention, when the hollow molded article itself has rigidity, since the foam piece has a shape having a porosity of 45% or more at the time of close packing, steam easily penetrates into each other. , Steam pressure can be reduced. Therefore,
If the strength of the hollow molded body is high, it is possible without the mold for producing a foamed molded body with a skin as described above.

FIG. 3 shows an example of a foam molded article 2 with a skin according to the present invention, 3 is a hollow molded article, and 4 is a foam piece molded article formed by fusing the foam pieces 1 to each other. FIG. 5 schematically shows an example of an apparatus for manufacturing a foamed molded article with a skin according to the present invention. In the figure, reference numeral 5 denotes a mold, and reference numeral 6 denotes a feeder for filling the hollow molded article with foam pieces. As the filling method, a known filling method such as a compression filling method and a pressure filling method can be adopted. Reference numerals 7 and 8 denote pins for supplying heating steam, sucking the supplied steam, and sucking the drain of steam.
Guided by the air cylinders 9 and 10 slid, the mold 5
Foam piece 1 filled in hollow molded body 3 mounted inside
Can be inserted into the layer or pulled out. The above-mentioned pin has many holes smaller than the foam piece, slit-shaped or circular holes, and can be formed by inserting one or a plurality of holes depending on the size of the hollow molded body.

As an example of a method for obtaining a foamed molded article with a skin in the present invention, after mounting the hollow molded article 3 in the mold 5, the foam piece 1 is filled into the hollow molded article 3 from the feeder 6, A method of heating the foam piece 1 by supplying steam for heating from one of the pins 7 and 8 inserted into the layer of the foam piece 1 filled in the hollow molded body 3 can be used. In this case, the steam is smoothed by sucking the steam from the other pin,
The supplied steam can be uniformly penetrated between the foam pieces 1. In addition, the pins are replaced every predetermined time and heated,
By performing suction, steam can be supplied more smoothly. After the heating steam is supplied, the heat or the drain accumulated between the foam pieces 1 can be efficiently discharged by suctioning from one or both of the pins 7 and 8. After heating and cooling in this manner, the pins 7 and 8 are pulled out, and the obtained molded body is taken out of the mold 5 and cured. Curing is preferably performed at 60 ° C. under atmospheric pressure for about 24 hours.

The foamed molded article with a skin obtained by covering at least a part of the surface of the molded foam piece of the present invention with a hollow molded article made of a thermoplastic resin is, for example, the entire surface of the molded thermoplastic foam piece. Foamed molded article with a skin, a foamed molded article with a skin that is not covered on two sides of an opening portion composed of a cylindrical hollow molded article penetrated and a foam piece molded article, and a cylindrical hollow molded article with a bottom A foamed molded article with a skin, which is not covered with one surface of the opening formed by the body and the foam piece molded article, is exemplified. Examples of the use of the foamed molded article with a skin of the present invention include, for example, a pallet, a distribution field such as a trolley, an insulating panel,
Examples include the construction field such as soundproof panels, the civil engineering field such as filtration materials and water permeable materials, various buoyancy members, automobile interiors, bumper materials, furniture, bedding, and the like.

[0047]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1 Ethylene-propylene block copolymer (MI = 0.6
g / 10 minutes (230 ° C, load 2.16 kgf), melting point 1
61 ° C., an ethylene content of 7.0% by weight) and an inner layer made of a propylene-ethylene random copolymer (MI = 8 g / 1)
A parison having a two-layer structure (a layer of a propylene-ethylene random copolymer on the inner side) consisting of 0 minute, melting point of 132 ° C. and ethylene content of 5.8% by weight was extruded from an extruder by a coextrusion method. Is supplied to the mold from above a mold (400 mm long × 250 mm wide × 100 mm deep) for manufacturing a hollow molded body, the mold is clamped while blowing air into a parison, and the hollow molded body (meat) is cooled. 2.6m thick
m). Next, the hollow molded body is mounted in a mold (396 mm in length, 248 mm in width, and 100 mm in depth) provided with a feeder for supplying foamed particles and used for producing a foamed molded body with a skin, and then closed with propylene-ethylene. Using a random copolymer (ethylene content: 2.4% by weight, melting point: 146 ° C.) as a base resin, cylindrical foamed particles having a shape shown in FIG. 1A (average particle weight: 2 mg, bulk expansion ratio: 20 times) , D
_MIN = 1.6 mm, D _MIN = 2.5 mm, d _MIN / D
_MIN = 0.64, L = 3.5 mm, L / D = 1.0, particle internal pressure 2.0 kg / cm ² (absolute pressure)) were filled in the hollow molded body.

When the hollow molded body is filled with the foamed particles, the air is filled while sucking air from both pins inserted into the hollow molded body, and then one of the pins inserted into the layer of the filled foamed particles is filled. Then, steam is supplied from the other pin while sucking for 5 seconds, and then the pin that has supplied steam and the pin that is sucking are exchanged. Steam is then supplied for 5 seconds while sucking, and the steam is supplied into the layer of expanded particles. After exhausting the remaining air, steam at 150 ° C. was supplied from both pins into the layer of the foamed particles to heat-mold the foamed particles. Next, after cooling by suction with a pin inserted into a layer of the foamed particles (at this time, the foamed particles are fused to each other), the mold was opened and the foamed molded article with a skin was taken out. This molded body was cured at 60 ° C. under atmospheric pressure for 24 hours and kept at room temperature. Table 1 shows the physical properties of the foamed particles used for molding, Table 2 shows the molding conditions, and Table 3 shows the physical properties of the foamed molded article with a skin obtained.

[0050]

[Table 1]

[0051]

[Table 2]

[0052]

[Table 3]

* 1 Depth of mold for producing hollow molded article and mold for producing foam molded article with skin * 2 rPP: propylene-ethylene random copolymer bPP: propylene-ethylene block copolymer LLD: linear Low density polyethylene HDPE: High density polyethylene * 3 rPP: Propylene-ethylene random copolymer bPP: Propylene-ethylene block copolymer LLD: Linear low density polyethylene

* 4 Bending rupture test: The fusion property of the foam pieces (expanded particles) was evaluated. Specifically, as shown in FIG. 5, the inside of the foamed molded article with the skin (A) and the vicinity of the skin (B) Sample (size: 25 mm x 25 mm x
(100 mm) was bent and broken, and each fracture surface was observed. ○: Most of the foam pieces (foamed particles) were broken. Δ: Material destruction of foam pieces (foam particles) and interfacial peeling between foam particles are mixed. X: Most of the foam pieces (expanded particles) are peeled off at the interface. Was evaluated.

* 5 The fusion property between the skin material and the foam piece (foamed particles) was determined by conducting a 90 ° peel test of the skin material on a sample obtained by cutting a foam molded article with a skin into a width of 15 mm. The state of the (foamed particles) was observed. ○: Most of the foam pieces (foamed particles) were broken. ×: Most of the foam pieces (expanded particles) are peeled off at the interface. Was evaluated.

Example 2 A foamed molded article with a skin was obtained under the same conditions as in Example 1, except that the cylindrical expanded particles having a bulk expansion ratio of 10 times and shown in FIG. 1A were used. Table 1 shows the physical properties of the expanded particles used.
Table 2 shows the molding conditions, and Table 3 shows the physical properties of the foamed molded article with a skin.

Example 3 A foamed molded article with a skin was obtained under the same conditions as in Example 1 except that the depth of the mold for producing a hollow molded article and the mold for producing a foamed molded article with a skin were 150 mm. Table 1 shows the physical properties of the foamed particles used, Table 2 shows the molding conditions, and Table 3 shows the physical properties of the foamed molded article with the obtained skin.

Example 4 A foamed molded article with a skin was obtained under the same conditions as in Example 3 except that the thickness of the hollow molded article was 1.5 mm. Table 1 shows the physical properties of the foamed particles used, Table 2 shows the molding conditions, and Table 3 shows the physical properties of the foamed molded article with the obtained skin.

Example 5 A parison was supplied to a mold (depth: 150 mm) for producing a foamed molded article having a skin, which also has a function of molding a hollow molded article, and the hollow molded article was molded. A foamed molded article with a skin was obtained under the same conditions as in Example 4, except that the foamed particles were filled and molded into the hollow molded article in the state of being folded. Table 1 shows various physical properties of the foamed particles used, and Table 2 shows molding conditions.
Table 3 shows various physical properties of the foamed molded article with a skin.

Example 6 As a hollow molded article, the inner layer side was a linear low-density polyethylene (MI = 1.3 g / 10 min (190 ° C., load 2.16 k
gf), a layer having a melting point of 124 ° C.) and a layer having a high density polyethylene (MI = 0.8 g / 10 min, melting point of 134 ° C.) on the outer layer side. (A) (1.3 g / 10 min, melting point 124 ° C.) as a base resin, cylindrical foamed particles (average particle weight 2 mg, bulk expansion ratio 20 times, d _MIN =
1.3 mm, D _MIN = 2.8 mm, d _MIN / D _MIN =
0.46, L = 3.2 mm, L / D = 1.0, internal pressure 1.
A foamed molded article with a skin was obtained under the same conditions as in Example 1 except that the pressure was 0 kg / cm ² (absolute pressure). Table 1 shows the physical properties of the foamed particles used, Table 2 shows the molding conditions, and Table 3 shows the physical properties of the foamed molded article with the obtained skin.

Example 7 A foam molded article with a skin was obtained under the same conditions as in Example 6, except that the depth of the mold for producing a hollow molded article and the mold for producing a foam molded article with a skin were 150 mm. Table 1 shows the physical properties of the foamed particles used, Table 2 shows the molding conditions, and Table 3 shows the physical properties of the foamed molded article with the obtained skin.

Example 8 Molding was carried out in the same manner as in Example 4, except that cylindrical expanded particles having L / D = 5 were used as expanded particles. Table 1 shows the physical properties of the foamed particles used, Table 2 shows the molding conditions, and Table 3 shows the physical properties of the foamed molded article with the obtained skin.

Example 9 Molding was carried out in the same manner as in Example 4 except that the expanded particles having the shape shown in FIG. 4A were used. Table 1 shows the physical properties of the foamed particles used, Table 2 shows the molding conditions, and Table 3 shows the physical properties of the foamed molded article with the obtained skin.

Example 10 A linear low-density polyethylene (MI =
A foamed molded article with a skin was obtained under the same conditions as in Example 6, except that a single-layer structure (1.3 g / 10 minutes, melting point: 124 ° C.) was used. Table 1 shows the physical properties of the foamed particles used, Table 2 shows the molding conditions, and Table 3 shows the physical properties of the foamed molded article with the obtained skin.
Shown in

Example 11 A foam molded article with a skin was obtained under the same conditions as in Example 7 except that the hollow molded article of Example 4 was used as the hollow molded article. Table 1 shows the physical properties of the foamed particles used, Table 2 shows the molding conditions, and Table 3 shows the physical properties of the foamed molded article with the obtained skin.

Comparative Example 1 Molding was carried out under the same conditions as in Example 1 except that the expanded particle shape was substantially spherical. Table 1 shows the physical properties of the expanded particles used.
Table 2 shows the molding conditions, and Table 3 shows the physical properties of the foamed molded article with a skin.

Comparative Example 2 A hollow molded body was molded under the same conditions as in Comparative Example 1 except that the thickness of the hollow molded body was 1.5 mm. Table 1 shows the physical properties of the foamed particles used, Table 2 shows the molding conditions, and Table 3 shows the physical properties of the foamed molded article with the obtained skin.

Comparative Example 3 A foamed molded article with a skin was obtained under the same conditions as in Comparative Example 1 except that the depth of the mold for producing a hollow molded article and the mold for producing a foamed molded article with a skin were 150 mm. Table 1 shows the physical properties of the foamed particles used, Table 2 shows the molding conditions, and Table 3 shows the physical properties of the foamed molded article with the obtained skin.

Comparative Example 4 A foamed molded article with a skin was obtained under the same conditions as in Example 7, except that substantially spherical expanded particles were used as the expanded particles. Table 1 shows the physical properties of the foamed particles used, Table 2 shows the molding conditions, and Table 3 shows the physical properties of the foamed molded article with the obtained skin.

[0070]

As described above, according to the method of the present invention, a thermoplastic resin foam piece is filled in a hollow molded article made of a thermoplastic resin, and the foam piece is heated by a heating medium to form a foam piece. In the method for producing a foamed molded article with a skin to be fused together, a void fraction of 45 at the time of closest packing is used as the foam piece.
% Or more, even if the hollow molded article has poor permeability to the heating medium, the heating medium sufficiently permeates between the foam pieces filled inside the hollow molded article,
As a result, the foam pieces filled into the hollow molded body are fused well, and even when the thickness of the hollow molded body becomes thick or the shape becomes complicated, Can be obtained. Further, when the inner layer side of the hollow molded article has a fusion property with the foam piece, a foam molded article with a skin excellent in the fusion property between the foam piece molded article and the hollow molded article can be obtained. Further, according to the method of the present invention, the foam piece molded article and the hollow molded article can be integrated at the time of molding the foam piece, so that the production efficiency of the foam molded article with skin is excellent. Further, when the thermoplastic resin foam pieces to be filled into the hollow molded body made of a thermoplastic resin are cylindrical foamed particles, even when the base resin of the foam pieces (foamed particles) is an olefin-based resin, The heating medium can penetrate to the deep layer, and the expanded particles can be reliably fused. Thus, a foamed molded article with a skin having excellent fusion property can be obtained.

Further, the foamed molded article with a skin of the present invention has a skin formed by covering at least a part of the surface of a thermoplastic resin foam piece molded article having communicating voids with a hollow molded article made of a thermoplastic resin. The foam molded article has a porosity of 5% or more, and most of the foam piece does not peel off at the interfacial surface in a bending fracture test as shown in Examples. Since the pieces are fused together, they have excellent strength, air permeability, sound absorption, etc., and in the construction field, air-permeable insulation panels, sound absorption, soundproofing panels, etc.
Further, in the field of civil engineering, it has an effect that it can be suitably used as a filtering material, a water permeable material, a water retaining material, and the like.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of the shape of a foam piece used in the present invention.

FIG. 2 is a schematic view showing an example of columnar expanded particles used in the present invention.

FIG. 3 is a longitudinal sectional view showing an example of a foam molded article with a skin according to the present invention.

FIG. 4 is a schematic view showing an example of a foamed particle having a projection used in the present invention.

FIG. 5 is a schematic sectional view showing an example of a production process of the foam molded article with a skin of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Foam piece 2 Foam molded article with skin 3 Hollow molded article 4 Foam piece molded article 5 Mold for producing foam molded article with skin 6 Feeder 7, 8 pin 9, 10 Air cylinder

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akinori Taira 1078-4 Komao-cho, Utsunomiya-city, Tochigi 2022. 4F100 AK01A AK01B AK64 BA02 CA01B DA11B DD31A DE01B DJ01B GB90 JB16A JB16B YY00B 4F212 AA05 AA08 AA11 AG03 AG20 AH26 AH48 AH56 AK01 UA07 UB01 UB14 UC01 UC06

Claims (3)

[Claims] 1. A foam molding with a skin in which a thermoplastic resin foam piece is filled into a hollow molded body made of a thermoplastic resin, and the foam piece is heated by a heating medium to fuse the foam pieces to each other. A method for producing a foam, wherein the foam piece has a shape having a voidage of 45% or more at the time of closest packing. 2. The method for producing a foamed molded article with a skin according to claim 1, wherein the thermoplastic resin foam pieces to be filled in the hollow molded article made of a thermoplastic resin are tubular thermoplastic resin foamed particles. 3. A foamed molded article with a skin obtained by covering at least a part of the surface of a molded article of a thermoplastic resin foam having communicating voids with a hollow molded article made of a thermoplastic resin. A foam molded article with a skin, wherein the porosity of the foam piece molded article is 5% or more.