JPH058315A - Method of molding foam synthetic resin - Google Patents

Abstract

PURPOSE:To solve various defects being inherent in moldings which are molded by filling and then foam-melting foamable synthetic resin particles into a pair of in-mold foam forming molds. CONSTITUTION:Non-foamable synthetic resin in the form of particles, powders, flakes and the like is supplied in molds wherein a suitable part or the entire surface of a front surface at the side of a forming space 4 in a pair of in-mold foam synthetic, forming molds is heated higher than the melting temperature of the resin, and the resin being in contact with the front surface at the side of the heated forming space 4 is heat-melted for forming a molten resin layer, in addition, foamable synthetic resin particles are allowed to be filled in a remained forming space of the clamped molds so as to form a superficial skin film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is to solve various drawbacks of a molded article obtained by filling a pair of in-mold foam molding dies with expandable synthetic resin particles and foam-melting them. To a method for molding a foamed synthetic resin molded article made in.

[0002]

2. Description of the Related Art Conventionally, molded articles obtained by filling expandable synthetic resin particles in a pair of in-mold foam molding dies and foam-fusing them together are lightweight, easy to handle, and have excellent cushioning performance. Since it is excellent, it is widely used in various cushioning materials and storage boxes.

[0003]

However, although such a general foamed synthetic resin molded article has a very thin skin on the surface, when it is rubbed against or hits another object, this skin is easily formed. It may peel off or the surface may be easily dented. In addition, such a phenomenon tends to occur more easily when it is repeatedly used or washed with water. Furthermore, such a skin is formed by foam fusion of many particles,
Since it is not thick and continuous, there are problems that the overall strength is low and it is brittle. Further, there is also a problem that individual particles appear on the surface as a hexagonal pattern and dents are formed between the particles, so that the surface condition is not necessarily beautiful.

From the above, it is considered that a non-foamed synthetic resin sheet is attached to the surface of the foamed synthetic resin molded product after molding to form a film, but it is melted to such an extent that only the surface is bonded. It is extremely difficult to work without wrinkling of the sheet in both cases of attaching the sheet or attaching the sheet with an adhesive. Especially, when the shape of the molded article on which the film is provided is complicated, this tendency is particularly remarkable. It is also conceivable that the surface of the molded product is heated and melted by post-processing after molding to form a film. In this case, not only is the molding step performed in two steps, but it is difficult to uniformly melt the particles, and there is a problem that the surface of the molded product becomes wavy.

Further, it has been attempted to insert a non-foamed synthetic resin sheet into the mold for in-mold foam molding before filling the expandable synthetic resin particles, and then perform foam molding. However, it is troublesome to insert the non-foamed synthetic resin sheet into the mold, and there is a problem that the surface is not beautifully finished due to the generation of wrinkles and the like.

A method for molding a foamed synthetic resin molded article according to the present invention was devised in view of the above conventional problems, in which a foamable synthetic resin particle is provided in a pair of molds for foam molding in a mold. It is an object of the present invention to solve various drawbacks of a molded product that is molded by filling in, foaming and fusing.

[0007]

In order to achieve such an object, according to claim 1 of the present invention, a non-foamed synthetic resin in the form of particles, powder, flakes, etc. is used as a pair consisting of a cavity mold and a core mold. Part of the molding space side surface of the in-mold foam molding die is supplied into the mold heated above the melting temperature of this resin, and the resin that has contacted the heated molding space side surface To form a molten resin layer by heating and melting, and then to fill the remaining molding space of the mold with the expandable synthetic resin particles closed, and to summarize the molding method of the foamed synthetic resin molded product with the surface film formed. To do. Further, in claim 2, a non-foaming synthetic resin in the form of particles, powder, flakes or the like having a size and shape capable of being fed by air is used to form a pair of in-mold foaming molds including a cavity mold and a core mold. Part of the molding space side surface of the mold is filled with air in the molding space formed by closing the mold of the mold heated above the melting temperature of this resin, and the heated molding space side surface The resin contacted with is melted by heating to form a molten resin layer, then the non-fusing resin is discharged out of the mold, and then the heated molding space side surface of the mold is cooled to a temperature below the normal foam molding temperature. , Further, expandable synthetic resin particles are filled in the molding space of the mold closed with a required gap left,
The particles are heated and foamed, and then the mold is cooled to form a foamed synthetic resin molded article having a surface film formed thereon. In Claim 3, particles and powder having a size and shape capable of being air-fed. A non-foamed synthetic resin in the form of a body, a thin piece, etc., where the molding space side surface of a pair of in-mold foaming molds consisting of a cavity mold and a core mold is at a suitable place or the whole surface is above the melting temperature of this resin The air is supplied to the molding space formed by closing the mold by heating the mold, and the air is circulated in the molding space to heat and melt the resin in contact with the heated molding space side surface. To form a molten resin layer, then the non-fusing resin is discharged to the outside of the mold, and then the heated molding space side surface of the mold is cooled to a temperature below the normal foam molding temperature, and the expandable synthetic resin particles are further added. Fill the remaining molding space of the mold closed with the required gap. The particles are heated foam, then the mold is cooled, and the forming method of the gist each surface film formed by foamed synthetic resin molded article. Also, claim 4
Then, the non-foaming synthetic resin in the form of particles, powder, flakes, etc.
The entire molding space side surface of a pair of in-mold foam molding molds consisting of a cavity mold and a core mold is fed into the mold heated above the melting temperature of this resin, and the heated molding space The resin contacting the side surface is heated and melted to form a molten resin layer, then the non-fusing resin is discharged outside the mold, and the expandable synthetic resin particles are closed in the remaining molding space of the mold. The method of molding a foamed synthetic resin molded article having a surface film formed by filling the same in a mold and then cooling the mold is the gist.

[0008]

With the cushioning material, for example, the inner surface of the inner surface which is in direct contact with the contents is enhanced in cushioning properties with the contents, a good surface film with improved non-peelability is formed, or the container is contained. In such a case, for example, such a good surface coating is formed on the outer surface exposed to the outside. In addition, such a surface coating can be formed on a desired portion or the entire surface of various molded articles.

[0009]

EXAMPLES The method for molding the foamed synthetic resin molded article according to the present invention will be described in more detail with reference to a molding die.

When a box-shaped molded article 1 as shown in FIG. 1 is molded, a pair of in-mold foam molding dies consisting of a cavity mold and a core mold as shown in FIG. 2 are usually used. .
In FIG. 2, 2 is a cavity mold, 3 is a core mold, and when the pair of molds 2 and 3 is closed, a molded product 1 is molded between them 4 A molding space shown as is formed. In the figure, 5 is a filling feeder for filling the expandable synthetic resin particles into the molding space 4, and 6 and 7 are heating compartments formed in a closed shape behind the cavity mold 2 and the core mold 3 on the molding space 4 side. A chamber, 8 is a ventilation opening for communicating the surfaces of the molds 2 and 3 on the side of the molding space 4 with the interiors of the heating compartments 6 and 7, and 9 is steam whose one end is seen inside the heating compartments 6 and 7. Pipe, 10 is a water pipe with one end inserted into both heating compartments 6 and 7, 11 is an air supply pipe with one end inserted into both heating compartments 6 and 7, 12 is a drain pipe, 13 is a release pin Is. or,
14 is an injection nozzle provided in the water pipe 10 toward the molding space 4 side,
Reference numeral 15 denotes an air supply port which is also provided at the end of the air supply pipe 11 toward the molding space 4 side. Further, 16, 17 and 18 are a back plate, a side plate and an inner plate, and 19 and 20 are a cavity side surface member and a core side surface member forming the surfaces of the molds 2 and 3 on the molding space 4 side, respectively. From the back plate 16, the side plate 17, the inner plate 18, the cavity side surface member 19, and the core side surface member 20, the heating compartment 6 is closed behind the cavity mold 2 and the core mold 3 on the side of the molding space 4 side. , 7 are formed.

A molded product 1 as shown in FIG. 1 is molded in the following manner by utilizing such an in-mold foam molding mold. First, the cavity mold 2 and the core mold 3 are closed with a required gap left therebetween, and the molding space 4 is filled with expandable synthetic resin particles through a filling feeder 5. Next, the mold is completely closed, steam is supplied to both heating compartments 6 and 7 from the steam pipe 9, and the particles are foamed and fused to form the molded product 1. Thereafter, water is sprayed from the spray nozzle 14 of the water pipe 10 to cool both molds 2 and 3, and the air supply pipe 11
Compressed air or the like is blown from the air supply port 15 to cool both molds 2 and 3 and to scatter and remove water. And a pair of molds 2,
The mold 3 is opened, and the molded product 1 is taken out from the molding space 4 by the operation of the mold release pin 13.

However, although such a molded article 1 has a very thin skin on the surface, it may be rubbed against other objects,
When hit, the epidermis is easily peeled off or the surface is easily dented. In addition, such a phenomenon tends to occur more easily when it is repeatedly used or washed with water. Then, in the molded product 1 such as a returnable box in which the contained items are frequently used and stored repeatedly, such a phenomenon remarkably appears on the inner surface which rubs against the contained items and may not be used for a long period of time. Further, there is a problem that the whole strength is small and it is brittle.

In view of the above, according to the present invention, particles on the inner surface of the molded article 1 shown in FIG.
The surface film 21 is provided from a molten resin layer formed by heating and melting a non-foaming synthetic resin in the form of powder, flakes, or the like.

In order to mold such a molded article 1, according to the present invention, the core side surface member 20 of the core die 3 for molding the inner surface of the molded article 1 is replaced with a conventional one, and the core member shown in FIG.
The core side surface member indicated by 22 is used. In this structure, a core-side back surface member 23 is provided behind the molding space 4 to form a closed heating gap 24, and a casting heater 25 serving as heating means is incorporated in the heating gap 24. . Normally, the conventional core-side surface member 20 is provided with the ventilation opening 8 as shown in FIG. 2, but the core-side surface member indicated by 22 in this figure has a ventilation opening 8 as described later. Since the steam or other heating medium used in the normal in-mold foam molding process does not always pass through after the surface film 21 is formed, such a vent opening 8 may not be provided.

Then, in order to mold the molded article 1 as shown in FIG. 1, the following is carried out. First, instead of the core side surface member 22 shown in FIG.
The cavity mold 2 and the core mold 3 as shown in FIG. 4 are assembled into a pair of in-mold foam molding molds to form a mold schematically shown in FIG. In addition, a hopper containing a non-foaming synthetic resin (hereinafter sometimes simply referred to as a resin) in the form of particles, powder, flakes, etc. having a size and shape capable of air feeding, and a resin of the same kind as this resin The hoppers containing the expandable synthetic resin particles are connected to the pipes whose one ends are connected to the side opposite to the molding space 4 side of the filling feeder 5, and the pipes branched from the middle are connected to each other, and valves are provided at appropriate places. Then, as shown in FIG. 5, the cavity mold 2 and the core mold 3 are closed while leaving a required gap, for example, a gap of about 15 mm, and then only the hopper on the resin-filled side is opened and the molding is performed. The space 4 is filled with resin by feeding compressed air through the filling feeder 5. At this time, although the ventilation opening 8 is not provided in the core mold 3, a ventilation gap 26 is formed between the inner peripheral surface of the cavity mold 2 and the outer peripheral surface of the core mold 3 as shown in FIG. Therefore, the compressed air that has passed through the filling feeder 5 passes from the ventilation opening 8 provided in the cavity mold 2 to the heating compartment 6, and also from the ventilation gap 26 to the outside between the molds 2 and 3. Can be released to
Can be filled with resin. When cracking filling is performed by a normal in-mold foam molding method, the gap between the two molds 2 and 3 is about 5 mm.
It is preferable that the gap between them should be larger than this.
Next, the two molds 2 and 3 are completely closed as shown in FIG. 4, and resin is forcibly pressure-bonded to the surface of the molding space 4 side of the mold, so that the casting heater 25 serving as heating means is energized in advance, For example, the molten resin layer is formed by heating and melting the resin that is in contact with the surface of the core mold 3 on the side of the molding space 4 that has been heated in advance to a melting temperature of the resin such as about 200 ° C. or the like.
Then, after a lapse of time in which the molten resin layer is formed evenly and almost uniformly on the surface of the core mold 3 on the side of the molding space 4 measured in advance, suction is made from the filling feeder 5 to mold the non-fusion resin. It is discharged from the space 4. After that, compressed air is blown from the air supply port 15 of the air supply pipe 11 which is looked into the heating compartment 7 of the core mold 3 to make the surface of the core mold 3 on the side of the molding space 4 at a normal foam molding temperature, For example, in the case of expandable polystyrene or polyolefin, the temperature is cooled to about 105 to 110 ° C or lower. Furthermore, only the hopper on the side containing the expandable synthetic resin particles (hereinafter sometimes simply referred to as particles) is opened, and the mold is closed while leaving a gap to the extent that conventional cracking filling is performed. The particles are filled into the molding space 4 by feeding compressed air through the filling feeder 5. Then, the mold is completely closed, and the layer formed of the molten resin layer and the respective particles are sufficiently brought into close contact with each other.
Steam is supplied from the steam pipe 9 to the heating compartments 6 and 7 of 3,
The surfaces of the cavity mold 2 and the core mold 3 on the molding space 4 side,
In the case of a normal foam molding temperature, for example, in the case of expandable polystyrene, polyolefin, etc., it is heated to about 105 to 110 ° C. to fuse the molten resin layer and each particle, and at the same time, the particles are foam-fused. Next, water is sprayed from the spray nozzle 14 of the water pipe 10 to cool both molds 2 and 3, and compressed air or the like is sprayed from the air supply port 15 of the air supply pipe 11 to both molds 2. Three
Cooling, water scattering and removal. Then, the pair of molds 2 and 3 are opened, and an in-mold foam molding process is performed from the molding space 4 to an inner surface side surface corresponding to the molding space 4 side surface of the heated core mold 3 as shown in FIG. Then, the molded product 1 having the surface film 21 formed from the molten resin layer is taken out by the operation of the release pin 13.

Here, after the resin and particles are filled, both molds 2,
In some cases, the operation of completely closing the mold 3 and the operation of opening a gap between the molds 2 and 3 are repeated. Then, after the molds 2 and 3 are completely closed, when a gap is opened between the molds 2 and 3, the resin and particles can be filled again. Further, the casting heater 25 serving as a heating means may be energized in advance before the resin is filled to heat the surface of the core mold 3 on the side of the molding space 4 or may be energized and heated after the resin is filled. . The heating temperature for forming the surface film 21 is preferably equal to or higher than the melting temperature of the resin used, and is 200 in the above.
Although an example of the temperature is about ° C, it varies depending on the type of resin, so it is desirable to select the optimum temperature by actually performing temporary molding. The lower the heating temperature, the more beautiful the surface condition of the obtained molded product 1. Further, water cooling using the water pipe 10 is used for cooling the core mold 3 to a temperature below the normal foaming molding temperature prior to the filling of the particles into the molding space 4, or water cooling and an air supply pipe.
It is also possible to use air cooling by 10. Further, when cooling both molds 2 and 3 after the usual in-mold foam molding process, it is possible to blow compressed air from the air supply port 15 of the air supply pipe 11 without using the water pipe 10. Furthermore, when water is jetted from the jet nozzle 14 of the water pipe 10 to cool both molds 2 and 3, and then the pressure inside both heating compartments 6 and 7 is reduced to further cool and scatter and remove water. There is also. In addition, as described above, of the resin filled in the molding space 4 of the mold closed with the required gap left, except for heating and melting by contacting the surface of the heated core mold 3 on the molding space 4 side. When the non-fusing resin is discharged to the outside of the mold, it is also possible to pressurize the inside of the heating compartment 6 of the cavity mold 2.

According to this molding method, the surface coating 21 is formed on the surface of the molded product 1 from a layer formed of a molten resin layer obtained by heating and melting the resin in contact with the molding space 4 side surface of the core mold 3. Moreover, it was possible to form a structure as schematically shown in FIG. 7 in which the molten resin layer and each particle were fused and the particles were foamed and fused. In addition, 27 in FIG. 7 is a molded product 1.
The particles which are foam-fused to each other and constitute the above are shown.

Even when the core side surface member 28 shown in FIG. 8 is used in place of the core side surface member 22 shown in FIG. 3, the same effect can be expected. The core-side surface member 28 does not have the core-side back surface member 23 behind the molding space 4 side, but a pair of partitioning members 29, 29 are provided on the opposite side of the molding space 4 side surface with a space between them. A heating gap 30 is formed, and a casting heater 25 serving as heating means is incorporated in the heating gap 30. Then, the heating gap 30 of the core side surface member 28.
The water pipe 10 and the air supply pipe 11 are provided so as to penetrate through the injection nozzle 14 and the air supply port 15 toward the molding space 4 side.

When the core side back surface members 22 and 28 shown in FIG. 3 or 8 are incorporated in the molding die shown in FIG. 4, the mold is closed with a required gap as in the above-mentioned molding method. In addition to filling the resin into the molding space 4 of the mold, the resin is not filled in the molding space 4 of the mold closed with a required gap or a gap for performing conventional cracking filling, as described above. While supplying a certain amount of air, the resin is circulated in the molding space 4 and the resin contacting the surface of the heated core mold 3 on the molding space 4 side is heated and melted to melt the resin layer. Can also be formed. Then, in this case, the non-fusing resin other than being heated and fused by coming into contact with the heated molding space 4 side surface is discharged out of the mold. At this time, it is considered that the air inlet side of the air inlet / outlet means such as a blower is connected to the side opposite to the molding space 4 side of the filling feeder 5, and the air inlet side thereof is connected to the drain pipe 12. or,
It is also possible to circulate the resin in the molding space 4 of the mold to form a molten resin layer to some extent, and then fill the molding space 4 with the resin to increase the thickness of the molten resin layer.

By the way, in consideration of foaming and fusing particles, at least appropriate openings 8 are provided in the molds 2 and 3 on the molding space 4 side, and steam or other heating is provided inside the molding space 4. It is necessary to pass the medium, and generally, the surface coating 21 cannot be provided on the entire surface of the molded article 1. However, such molding is also possible when the particles are not foamed and fused. At this time, the in-mold foam molding die shown in FIG. 9 is used. In this molding die, not only the core die 3 but also the cavity-side back member 31 or a pair of partition members (not shown) spaced apart are provided behind the cavity mold 2 on the side of the molding space 4 to form a closed shape. The heating gap 32 or a heating gap (not shown) having the same form as that of FIG. 8 is formed. Similar to the above, the molding die is closed with a required gap left, and the molding space 4 is filled with resin. Next, the mold is completely closed, the resin is forcibly pressure-bonded to the surface of the molding space 4 side, and the resin in contact with the heated molding space 4 side surface is heated and melted to form a molten resin layer. After that, both molds 2 and 3 are cooled to a temperature not higher than a normal foam molding temperature, and the non-fusing resin is discharged out of the mold. At this time, the non-fusing resin may be discharged to the outside of the mold, and then the molds 2 and 3 may be cooled to a temperature equal to or lower than the normal foam molding temperature. And, the particles are molded into the molding space 4
Fill inside. Also when the particles are filled into the molding space 4, a required gap or a gap for performing conventional cracking filling is opened, and then the mold is completely closed, as described above. According to this method, the particles 27 inside the molded article 1 are in a compressed state without foam fusion, as schematically shown in FIG. 10, but there is a thick continuous surface coating 21 on the surface. Therefore, the intended purpose of molding the molded product 1 having strength can be achieved. However, during such molding, a pipe body with holes for steam supply is projected inside the molding space 4, and steam or another heating medium is blown into the pipe body to remove particles inside. It is also possible to perform foam fusion. And in such a molding method,
After the resin contacting the surfaces of the molds 2 and 3 on the side of the molding space 4 is heated and melted, and the non-fusing resin in the molding space 4 is discharged, if the filling of particles is omitted, the hollow molded product 1 Can also be molded from resin.

The surface film 21 is provided on the inner surface and the entire surface of the molded product 1 shown in the figure, and a part of the cavity mold 2 and the core mold 3 on the molding space 4 side is heated to form various molded products. It is also possible to provide such a surface coating 21 on a desired portion of the.

Further, when the resin is supplied into the mold heated at a certain position or the entire surface of the molding space 4 side, the mold is completely opened. It is also possible to employ various means such as spraying resin with a nozzle toward the surface of the heated molding space 4 side, or sprinkling the resin. At this time, the resin is not always large enough to supply air,
It is not necessary to form in the form of shaped particles, powder, flakes or the like.

Regardless of the illustrated embodiment, the heating gap
It is also possible to cause heating oil or steam to flow through the spaces 24, 32 or the heating gap 30. Further, when the molding space 4 is filled with the resin and particles, the molding space 4 can be compressed and filled with compressed air. Further, it is also considered as appropriate to provide the ventilation communicating portion 8 on the side of the molding space 4 of the cavity mold 2 and the core mold 3 to be heated.

In such a molding method, in addition to styrene resins such as polystyrene, polyolefin resins such as polyethylene and polypropylene, various non-foaming synthetic resins such as copolymers, and foaming synthetic resins can be used. Among them, polyethylene and polypropylene are preferable raw materials because the surface film 21 is easily formed. In addition, since the polypropylene film has excellent bending resistance, it is suitable for a hinge portion of a foam container with a lid and the like. Although these resins may be crosslinked or non-crosslinked, non-crosslinked ones can be preferably used for forming a good surface film 21 from the molten resin layer.

Further, it is not always necessary to use the same kind of resin for the resin and the particles, and it is of course possible to use different kinds of resins.

[0026]

The foamed synthetic resin molded article molded by the molding method according to the present invention as described above has a continuous surface film having a thickness obtained by heating and melting the non-foamed synthetic resin on a part or the entire surface thereof. Since it is formed, the surface is not easily peeled off or easily dented even if it is rubbed or hit, without impairing the advantages of the conventional foamed synthetic resin molded article. Further, the strength of the whole is increased by the surface coating, and the surface condition is beautiful. Further, when molding such a molded product, it is possible to use the conventional foam molding machine as it is and to slightly modify a part of the in-mold foam molding die, which is industrially very useful.

Further, in such a molding method, since the resin is once heated and melted in the molding process to form the surface film, it is possible to deal with it by slightly changing the conventional in-mold foam molding procedure, and the work is efficient. Not only is there no possibility of wrinkling on the surface film. Furthermore, by engraving an appropriate pattern on the surface of the mold where the surface film is to be formed on the side of the molding space, or by providing a net-like object,
By adding various designs to the surface of this surface film or making it matte, it is possible to further enhance the commercial value.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of a foamed synthetic resin molded product molded by a molding method according to the present invention.

FIG. 2 is a vertical cross-sectional view showing an example of a conventional in-mold foam molding die.

FIG. 3 is a longitudinal sectional view showing an example of a main part of a molding die used in a molding method according to the present invention.

FIG. 4 is an explanatory view showing an outline of a molding die used in the molding method according to the present invention.

FIG. 5 is an explanatory view showing an outline of a state where the molding die is closed with a required gap left therebetween.

FIG. 6 is an explanatory view showing a main part of this molding die.

FIG. 7 is an explanatory view schematically showing the structure of a molded product molded by the molding method according to the present invention.

FIG. 8 is a vertical cross-sectional view showing another example of the main part of the molding die used in the molding method according to the present invention.

FIG. 9 is an explanatory view showing the outline of another example of the molding die used in the molding method according to the present invention.

FIG. 10 is an explanatory view schematically showing the structure of a molded product molded by another molding method according to the present invention.

[Explanation of symbols]

1 molded product 2 cavity mold 3 core mold 4 molding space 5 Filling feeder 6 heating compartments 7 heating compartment 8 ventilation openings 9 steam pipe 10 water pipe 11 Air line 12 Drain pipe 13 Release pin 14 injection nozzle 15 Air outlet 16 back plate 17 side plate 18 Inner plate 19 Cavity side surface member 20 Core side surface material 21 Surface coating 22 Core side surface material 23 Core side backside member 24 Heating gap 25 Casting heater 26 Ventilation gap 27 Expandable synthetic resin particles 28 Core side backside member 29 partition members 30 heating gap 31 Cavity side backside member 32 heating gap

Continuation of front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location // B29K 105: 04 B29L 9:00

Claims (4)

[Claims] 1. A non-foamed synthetic resin in the form of particles, powders, flakes, etc. is applied to a part or whole of the molding space side surface of a pair of in-mold foam molding dies consisting of a cavity die and a core die. Is supplied into a mold heated above the melting temperature of the resin to heat and melt the resin in contact with the heated molding space side surface to form a molten resin layer, and further expandable synthetic resin particles are formed. A method for molding a foamed synthetic resin molded product having a surface film formed by filling the remaining molding space of a closed mold. 2. A non-foaming synthetic resin in the form of particles, powder, flakes or the like having a size and shape capable of being fed by air, is used in a pair of in-mold foaming molds composed of a cavity mold and a core mold. A part or all of the molding space side surface is filled with air into the molding space formed by closing the mold heated to the melting temperature of the resin or higher, and contacts the heated molding space side surface. The molten resin is heated and melted to form a molten resin layer, then the non-fusing resin is discharged out of the mold, and then the heated molding space side surface of the mold is cooled to a temperature equal to or lower than the normal foam molding temperature, and Expandable synthetic resin particles are filled with expandable synthetic resin particles in the molding space of a closed mold, leaving the required gaps, and the particles are heated and foamed, and then the mold is cooled to form a surface film. Molding method. 3. A pair of in-mold foam molding molds comprising a cavity mold and a core mold, wherein a non-foaming synthetic resin in the form of particles, powder, flakes or the like having a size and shape capable of air feeding is used. A part or all of the molding space side surface is heated to a temperature above the melting temperature of the resin and air is fed into the molding space formed by closing the mold, and air is circulated in the molding space. Among the resins, the resin that contacts the heated molding space side surface is heated and melted to form a molten resin layer, and then the non-fusing resin is discharged outside the mold, and then the heated molding space side surface of the mold. Is cooled below the normal foaming temperature, and the expandable synthetic resin particles are filled into the remaining molding space of the closed mold with a required gap, and the particles are heated and foamed, and then the mold is closed. A method for molding a foamed synthetic resin molded article having a surface film formed by cooling the resin. 4. A non-foamed synthetic resin in the form of particles, powder, flakes, etc. is formed on the entire surface of the molding space side of a pair of in-mold foam molding dies consisting of a cavity die and a core die. It is supplied into the mold heated above the melting temperature of, and the resin in contact with the heated molding space side surface is heated and melted to form a molten resin layer, and then the non-fusing resin is placed outside the mold. A method for molding a foamed synthetic resin molded article having a surface film formed by discharging, further filling the expandable synthetic resin particles into the remaining molding space of the closed mold, and then cooling the mold.