Process for producing hollow resin molded article

According to the present invention, a hollow molded article of high quality can be produced by conducting the following steps of: PA1 providing a small-sized molding machine comprising a mold having a pair of mold halves wherein at least one of the mold halves comprises a body and a slidable block; PA1 supplying a resin in an unsolidified state between the mold halves to fill a mold cavity having a first clearance with the resin; PA1 supplying a pressured fluid into the resin lying between the mold surfaces; PA1 moving the slidable block from a first position to a second position; PA1 opening the mold until a cavity clearance becomes a second clearance which is larger than the first clearance; and PA1 opening the mold to take out the hollow molded article.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to a process for producing a resin molded
 article having a hollow space inside, the resin molded article,
 hereinafter, being referred to as a "hollow molded article".
 2. Description of the Related Art
 Japanese unexamined patent publication Nos. Hei 4-212822 and Hei 7-144336
 disclose a process for producing a hollow molded article utilizing an
 injection molding method having a core retracting system. In this process,
 a molten resin is injected with a high pressure into a cavity which is
 completely closed with a predetermined clearance. After filling the cavity
 with the resin, a movable core is retracted to expand the cavity while
 injecting a high-pressured gas into the molten resin. Consequently, a
 hollow space is formed in a resin substrate. However, such a method has
 been problematic in that a sink mark and a blister have been caused in a
 part of the hollow molded article in the vicinity of the hollow space and
 the appearance of the hollow molded article has been deteriorated because
 of the difference in a cooling speed of the resin and in a pressure
 applied to the resin between a part near to the hollow space and apart far
 from the hollow space. Additionally, there has been another problem that
 when molding of the hollow molded article and laminating of a skin
 material, such as one having a cushion layer and one having hair such as a
 carpet, onto a surface of the hollow molded article are carried out
 simultaneously, the cushion layer is crushed and the hair is laid in
 different degrees between the part near to the hollow space and the part
 far from the hollow space and the appearance of the hollow molded article
 is deteriorated.
 SUMMARY OF THE INVENTION
 The object of the present invention is to solve the problems of the
 conventional processes. Namely, one object of the present invention is to
 provide a process for producing a hollow molded article which has a hollow
 space extending throughout its inside and in which neither the sink mark
 nor blister is caused in the part near to the hollow space. Another object
 of the present invention is to provide a process for producing a hollow
 molded article having good appearance without causing differences both in
 a residual degree of the cushion layer and in a degree of hair-lying
 between the part near to the hollow space and the part far from the hollow
 space, even when a hollow molded article on which the skin material having
 the cushion layer and the hair is laminated is produced.
 According to the present invention, there is provided a process for
 producing a hollow molded article comprising the following steps of:
 Step (A) providing a molding machine comprising a mold including a first
 mold half and a second mold half, wherein the first mold half has a first
 mold surface, the second mold half has a second mold surface, the mold
 surfaces together define a cavity, at least one of the mold halves can
 move so that the mold surfaces approach and go away from each other, at
 least one of the mold halves comprises a body and a slidable block, the
 mold surface of the mold half comprising the body and the slidable block
 comprises a surface of the body and a surface of the slidable block, the
 slidable block can move from a first position to a second position, the
 movement of the slidable block from the first position to the second
 position expands the cavity;
 Step (B) supplying resin in an unsolidified state between the first mold
 surface and the second mold surface to fill the cavity with the resin,
 wherein the cavity has a first clearance;
 Step (C) supplying pressurized fluid into the resin lying between the mold
 surfaces;
 Step (D) moving the slidable block from the first position to the second
 position;
 Step (E) opening the mold until a cavity clearance becomes a second
 clearance which is larger than the first clearance; and
 Step (F) opening the mold to take out the hollow molded article.
 In one embodiment of the present invention, in Step (B), the resin in the
 unsolidified state may be supplied between the first mold half and the
 second mold half facing with each other with a clearance larger than the
 first clearance, and at least one mold half may be moved to press and
 spread the resin to fill the cavity with the same. In another embodiment
 of the present invention, Step (E) may be commenced at the same time when
 or after Step (D) is commenced. In still another embodiment of the present
 invention, Step (D) may be commenced after Step (E) is commenced. In yet
 another embodiment of the present invention, Step (D) may be commenced at
 the same time when or after Step (C) is commenced. In yet another
 embodiment of the present invention, Step (E) may be commenced at the same
 time when Step (C) is commenced. In yet another embodiment of the present
 invention, Step (C) may be commenced after Step (B) is commenced. In yet
 another embodiment of the present invention, Step (D) may be commenced
 after Step (B) is completed. In yet another embodiment of the present
 invention, Step (E) may be commenced after Step (B) is completed. In yet
 another embodiment, a further step of changing a pressure applied to the
 resin may be carried out after Step (B) is completed and before Step (E)
 is commenced. In yet another embodiment of the present invention, Step (C)
 may be commenced at the same time when or after the step of changing the
 pressure is commenced. In yet another embodiment, the step of changing the
 pressure is carried out after Step (B) is completed and after Step (E) is
 commenced, and Step (D) is commenced at the same time when or after the
 step of changing the pressure is commenced. In yet another embodiment of
 the present invention, in Step (B), supplying the resin is commenced at a
 time when the slidable block is located at the first position, and the
 mold surface of the slidable block existing at the first position is
 depressed below the surface of the body adjacent to the slidable block. In
 yet another embodiment of the present invention, a further step of
 supplying a skin material between the first mold surface and the second
 mold surface is carried out before Step (B) is commenced.
 Other objects, features, and advantages of this invention will be apparent
 from a consideration of the following detailed description thereof in
 conjunction with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
 FIG. 1 schematically illustrates one example of the molding machine which
 is used in the process of the present invention. The molding machine
 comprises the mold (1) including the first mold half (2) and the second
 mold half (3). Referring to FIG. 1, one example of the mold including a
 female mold half as the first mold half (2) and a male mold half as the
 second mold half (3) is shown. The mold surface of the first mold half
 (the first mold surface, 201) and the mold surface of the second mold half
 (the second mold surface, 301) can together define the cavity (6). The
 configuration of the mold surfaces is designed depending upon the shape of
 the desired hollow molded article. The molding machine may have a driving
 device (a clamping device) which can move at least one mold half in a
 linear direction so that the mold surfaces can approach and go away from
 each other. The linear direction is not necessarily restricted to a
 vertical direction, a substantially vertical direction, a horizontal
 direction or a substantially horizontal direction. It may be suitably
 determined depending upon a situation.
 At least one mold half includes the body (5) and the slidable block (4).
 The mold surface of the mold half including the body and the slidable
 block comprises at least a part of the surface of the body and at least a
 part of the surface of the slidable block. Although the slidable block is
 often provided in one mold half, it may be provided in both mold halves.
 One mold half may include a plurality of slidable blocks depending upon
 the shape of the desired hollow molded article. At least a part of the
 surface of the slidable block always faces and substantially contacts with
 at least a part of the surface of the body during the operation of the
 process of the present invention. Here, "the state in which the surface of
 the slidable block faces and substantially contacts with the surface of
 the body" means a state in which the slidable block is located close to
 the body so that the unsolidified resin does not leak through a gap
 between the surface of the slidable block and that of the body, and of
 course includes a state in which the slidable block tightly contacts with
 the body. The slidable block can move from the first position to the
 second position with at least a part of its surface substantially
 contacting with at least a part of the surface of the body. Both the first
 position and the second position of the slidable block are relative
 positions based on the position of the body which constitutes the mold
 half with the slidable block. The movement of the slidable block from the
 first position to the second position can expand the cavity and can
 increase the volume of the cavity. The concrete first position and second
 position, respectively, may be determined depending upon the size and the
 shape of the desired molded article and the position, the size and the
 shape of the desired hollow space. When a plurality of slidable blocks is
 provided, the first position and the second position of the slidable
 block, respectively, may be determined individually for each slidable
 block. The slidable block may be connected with a conventional driving
 means (7) such as a hydraulic cylinder and an air cylinder so as to move
 at least from the first position to the second position.
 The position in the mold half where the slidable block is provided is
 determined depending upon the shape of the desired hollow molded article.
 The configuration of the surface of the slidable block which constitutes a
 part of the mold surface of the mold half is designed depending upon the
 shape of the desired hollow molded article. When a plurality of slidable
 blocks is provided, the shape of each slidable block can be individually
 determined.
 The process of the present invention has a step of supplying the resin (8)
 in the unsolidified state between the mold surfaces (201, 301) of the
 first mold half (2) and the second mold half (3) to fill the cavity, which
 has a cavity clearance of the first clearance, with the resin. This step
 is referred to as "Step (B)".
 Step (B) can be carried out, mainly, by two ways. In the first way, the
 resin in the unsolidified state is injected into the cavity defined by the
 first mold half and the second mold half which are held with the first
 clearance therebetween. In the second way, the resin in the unsolidified
 state is supplied between the first mold half and the second mold half
 which face each other with a clearance larger than the first clearance
 therebetween, and the resin is pressed and spread by the movement of
 moving at least one mold half in the mold-closing direction, in other
 words, by a mold-clamping, to fill the cavity with the resin. Since the
 former method requires a high clamping force and a large molding machine,
 the latter method is preferable. In any way, it is preferred that the
 resin start to be supplied when the slidable block is located at the first
 position.
 In the present invention, "filling the cavity with the resin" means making
 a state in which whole or substantially whole mold surfaces, which define
 the cavity, contact with the resin. Therefore, it means substantially
 completely filling the cavity with the resin while leaving a little void
 between the mold surfaces and the resin, as well as completely filling the
 cavity with the resin. It is preferred to fill the cavity with the resin
 so that there is little void which contacts with the mold surfaces in the
 cavity. Additionally, the above-mentioned "filling the cavity with the
 resin" also means making the surface of the resin having a hollow space
 inside contact with the whole or substantially whole mold surfaces while
 simultaneously injecting the compressed gas into the resin, as well as
 filling the cavity with only the resin.
 In the aforementioned second method, the mold-clamping may be commenced
 either after the completion of supplying the resin or in the middle of
 supplying the resin. Alternatively, the mold-clamping may be commenced
 before the beginning of supplying resin. The mold-clamping may be
 completed either at the same time when or after supplying the resin is
 completed.
 A method for supplying the resin between the mold halves is not
 particularly limited. In order to prevent the resin from being excessively
 cooled before the beginning of supplying the pressurized fluid, it is
 preferred that the resin be directly supplied between the mold surfaces
 via a resin path (9) provided in at least one of the mold halves. The
 resin also may be supplied between the mold surfaces using a resin
 supplying machine which has a nozzle for injecting the resin and which is
 located outside the molding machine. This method is adopted when the
 mold-clamping is conducted after the completion of supplying resin.
 The process of the present invention has a step of supplying the
 pressurized fluid into the resin supplied between the mold surfaces of the
 mold halves. This step is referred to as "Step (C)".
 The pressurized fluid may be a material which is pressured and can flow and
 can be supplied into the resin to form a hollow space inside the same. The
 pressurized fluid may be a liquid which can be easily vaporized by heat of
 the resin into which the liquid is supplied, such as a liquefied carbon
 dioxide gas and water, as well as a gas. Alternatively, it may be granular
 or powdered solid, such as a foamable bead, which can easily generate gas
 due to, for example, decomposition by heat of the resin into which the
 solid is supplied. Normally, the pressurized fluid may be compressed gas
 such as compressed air, compressed nitrogen and compressed carbon dioxide.
 The injection pressure of the pressurized fluid may be set depending upon
 molding conditions, but it preferably is not less than about 1
 kgf/cm.sup.2 and less than about 10 kgf/cm.sup.2. Especially, compressed
 air having a pressure of not less than about 1 kgf/cm.sup.2 and less than
 about 10 kgf/cm.sup.2 is preferably employed. The injection pressure of
 the pressurized fluid may be either constant during injection of the same
 or changed in the middle of injection.
 In Step (C), the timing to commence supplying the pressurized fluid can be
 selected from a time after the resin which was supplied between the mold
 halves has reached a fluid-supply-opening (10) provided to at least one
 mold half and when it is possible both to supply the pressurized fluid
 into the resin and to form the hollow space (11) in the resin by the
 pressurized fluid. Therefore, Step (C) may be commenced in the middle of
 Step (B). However, it is preferred that the supply of the pressurized
 fluid be commenced between the completion of filling the cavity with the
 resin and the beginning of retracting the slidable block. Especially, the
 supply of the pressurized fluid is preferably commenced within a
 relatively short time, specifically within about 15 seconds, from the
 completion of filling the cavity with the resin. The pressurized fluid may
 be supplied continuously or intermittently until the resin solidifies.
 Alternatively, it is also possible that the supply of the pressurized
 fluid is stopped after the hollow space has been formed in the resin and
 then the resin is solidified while maintaining the pressure of the
 pressurized fluid in the hollow space.
 The pressurized fluid is not necessarily supplied into the resin at only
 one point, and may be supplied at multiple points depending upon the shape
 and the size of the desired hollow molded article. When the
 fluid-supply-opening is provided in the cavity surface of the slidable
 block as illustrated in FIG. 1, the hollow space can be efficiently formed
 and the hollow molded article having good appearance can be produced.
 When the compressed gas is employed as the pressurized fluid, it is
 possible to eject the compressed gas from the resin to let it flow through
 the hollow space formed in parallel with supplying the compressed gas into
 the resin, whereby cooling of the resin is promoted and the molding cycle
 is shortened.
 When the pressurized fluid is supplied into the resin through multiple
 fluid-supply-openings, it is possible that the pressurized fluid continues
 to be supplied through at least one fluid-supply-opening and it is ejected
 through at least one of the other fluid-supply-openings. Alternatively, it
 is also possible that a mold which has a fluid-eject-opening only for
 ejecting the pressurized fluid is used and the pressurized fluid is
 ejected from the resin through the fluid-eject-opening while supplying the
 pressurized fluid into the resin through the fluid-supply-opening. It is
 still also possible that the pressurized fluid is alternately repeatedly
 supplied and ejected through a common opening. However, a method for
 ejecting the pressurized fluid is not restricted to the above exemplified
 methods. The ejection of the pressurized fluid from the resin can be
 commenced at any suitable time after the beginning of supplying the
 pressurized fluid. For example, it may be commenced substantially at the
 same time when the supply of the pressurized fluid begins. The ejection of
 the pressurized fluid may be continued even after the supply thereof has
 been completed.
 The process of the present invention has a step of moving the slidable
 block from the first position to the second position. This step is
 referred to as "Step (D)". The cavity defined by the first mold half and
 the second mold half is expanded by the movement of the slidable block
 from the first position to the second position.
 The movement of the slidable block may be commenced after supplying the
 resin between the mold halves has begun. The concrete timing to commence
 the movement is set according to the size and the shape of the desired
 hollow molded article, the size, the shape and the position of the desired
 hollow space, the pressure of the pressurized fluid, the mold temperature,
 the type and the temperature of the resin used, the size and the stroke of
 the slidable block, and the like. For example, the slidable block may
 commence to be retracted in the middle of Step (B). Alternatively, the
 slidable block may begin to retract immediately after the cavity having
 the first clearance has been filled with the resin, in other words,
 immediately after the completion of Step (B). It is also possible that the
 slidable block begins to retract after a certain time has passed after the
 completion of Step (B). Concretely, it is preferred that the slidable
 block begins to retract within about 15 seconds after the completion of
 filling the cavity having the first clearance with the resin. Although the
 supply of the pressurized fluid and the retraction of the slidable block
 may be commenced at the same time or substantially at the same time, the
 supply of the pressurized fluid into the resin is preferably commenced
 prior to the retraction of the slidable block. Normally, the supply of the
 pressurized fluid is continued during the retraction of the slidable
 block.
 The movement of the slidable block, for example, can be controlled as
 follows. The slidable block which is connected with a cylinder such as a
 hydraulic cylinder and an air cylinder and which has been held at the
 first position can be moved to the second position by the operation of the
 cylinder at a predetermined time. Alternatively, the slidable block which
 has been held at the first position with a stopper may be retracted to the
 second position by both releasing the stopper and applying a pressure on
 the surface of the slidable block facing the cavity. When the slidable
 block is held at the first position by the stopper, the stopper can be
 easily released by decreasing, at the beginning of retracting the slidable
 block, a mold clamping force to reduce the pressure which is applied to
 the slidable block. At this time, since the pressure which is applied to
 the resin is also reduced, the hollow space can easily formed.
 By taking conditions such as the desired size of the hollow space, the
 injection pressure of the pressurized fluid, the mold temperature, the
 type and the temperature of the resin supplied, the size and the stroke of
 the slidable block into consideration, a moving speed of the slidable
 block can be determined.
 The process of the present invention has a step of opening the mold until
 the cavity clearance becomes the second clearance which is larger than the
 first clearance. This step is referred to as "Step (E)".
 In Step (E), the second clearance substantially corresponds to the
 thickness of the desired hollow molded article. The opening of the mold in
 Step (E) is conducted by the movement of at least one mold half. Step (E)
 may be commenced after the beginning of Step (B). A concrete timing to
 open the mold in Step (E) may be determined according to various molding
 conditions, the pressure of the pressurized fluid, the stroke of the mold
 halves and the like. For example, Step (E) may be commenced in the middle
 of Step (B). Step (E) also may be commenced immediately after Step (B). It
 is also possible that Step (E) may be commenced after a certain time has
 passed after the completion of Step (B). Step (E) also may be commenced
 after the beginning of Step (C). At least a part of Step (E) may be
 conducted with at least a part of Step (C). At least a part of Step (E)
 also may be performed with at least a part of Step (D). Although Step (E)
 may be completed before the beginning of Step (D), it is preferably
 commenced after the completion of Step (D). Especially, Step (E) is
 preferably commenced within a relatively short time, specifically within
 about 15 seconds, from the completion of Step (B). Performing Step (E)
 forms the hollow space approximately throughout the inside of the hollow
 molded article to uniformize the pressure which is applied to the entire
 hollow molded article, and produces the hollow molded article having good
 appearance.
 As mentioned above, the order of the beginning of Steps (C), (D) and (E) is
 arbitrary and a concrete order is suitably determined depending upon the
 size of the desired hollow molded article, the molding conditions, the
 pressure of the pressurized fluid, the size and the stroke of the slidable
 block, the stroke of the mold halves in Step (E) and the like. However, it
 is preferred that Step (C) is commenced within a relatively short time,
 specifically within about 15 seconds, from the completion of Step (B),
 Step (D) is commenced at the same time when Step (C) has been commenced or
 within a relatively short time after the beginning of Step (C), and Step
 (E) is commenced at the same time when Step (D) has been commenced or
 within a relatively short time after the beginning of Step (D).
 In the above-mentioned process, the pressure which is applied to the resin
 can be changed by changing the clamping force between the completion of
 Step (B) and the beginning of Step (E). For example, let P1 be the
 clamping force at the completion of Step (B). It is preferred that Steps
 (C) and (D) be commenced at the same time when or after the clamping force
 has been reduced from P1 to P2. In this case, Step (E) is conducted after
 the completion of Steps (C) and (D). Although the reduction of the
 clamping force may be done after the completion of Step (B), it is
 preferably conducted within a relatively short time, normally within about
 15 seconds, after the completion of Step (B).
 After the desired hollow space (11) has been formed in the resin and at a
 time when the resin has moderately solidified, a step of opening the mold
 to take the hollow molded article (12) out. This step is referred to as
 "Step (F)".
 A variety of resins, such as thermoplastic resins, thermoplastic elastomers
 and thermosetting resins, which are employed in conventional molding
 methods such as injection molding, injection compression molding,
 compression molding, extrusion molding and stamping molding can be
 utilized in the process of the present invention. For example, a
 conventional thermoplastic resin such as polyolefin resins, e.g.,
 polyethylene and polypropylene, polystyrene, polycarbonate,
 acrylonitrile-styrene-butadiene block copolymer and polyamide; a
 thermoplastic elastomer such as ethylene-propylene block copolymer and
 ethylene-butadiene block copolymer; and a polymer alloy thereof can be
 used. The resin may contain a variety of conventional additives such as a
 pigment, a lubricant, an antistatic agent and an antioxidant.
 For the purpose of decorating the surface of the hollow molded article and
 providing a cushion property to the hollow molded article, a skin material
 may be provided onto the surface of the hollow molded article. In the
 process described above, the hollow molded article onto whose surface the
 skin material is stuck can be produced by supplying the skin material
 between the mold halves before Step (B) and then performing the
 aforementioned steps. In this modified process, the resin is normally
 supplied to a rear side of a designed surface of the skin material.
 Although the skin material can be chosen depending upon use thereof, it
 may be paper, woven fabric, non-woven fabric, knit, a net such as wire
 gauze, a film or a sheet made of thermoplastic resin or thermoplastic
 elastomer. The skin material may have decorations such as print and an
 uneven pattern, e.g., an grain pattern on its surface. The skin material
 may be lined with a foamed sheet made of polypropylene, polyethylene,
 polyvinyl chloride, polyurethane and the like. The skin material may be
 lined with a thermoplastic elastomer sheet in order to protect the skin
 material from heat of the molten resin and a clamping pressure or in order
 to improve adhesiveness of the resin with the skin material.
 Conditions such as the temperature of the resin to be supplied, the cavity
 clearance which is defined when the resin is supplied, a mold clamping
 speed, the mold temperature may be determined according to the type of the
 resin to be used, the size and the shape of the mold, the type of the skin
 material and the like.
 According to the process of the present invention, the hollow molded
 article having a hollow space extending approximately throughout its
 inside and good appearance without having any sink mark and blister can be
 readily produced by using the simple and inexpensive molding machine. The
 obtained hollow molded article can be suitably employed as interior parts
 of an automobile such as an instrument panel, a door trim, a seat back, a
 console box and a deck board, and various panels.
 EXAMPLES
 The following Examples are preferred embodiments of the present invention,
 but they do not limit the scope of the present invention.
 Example 1
 A hollow molded article was produced by using a molding machine comprising
 a mold having a pair of a male mold half and a female mold half which
 could be vertically moved. The cross section of the molding machine is
 schematically illustrated in FIG. 1. The male mold half had a body and a
 slidable block. A projective shape of a cavity onto a imaginary plane
 being perpendicular to the mold closing direction was 320 mm long and 780
 mm wide. Aprojective shape of the slidable block onto that imaginary plane
 was 80 mm long and 740 mm wide. The top of the slidable block had a flat
 surface whose shape was identical to the projective shape of the slidable
 block.
 Positions where the slidable block was located with its top being 3.5 mm
 below and 17.5 mm below the mold surface of the body which was adjacent to
 the slidable block were, respectively, defined as the first position and
 the second position. Hence, a stroke of the slidable block was 14 mm. The
 slidable block could be moved in a vertical direction by a hydraulic
 cylinder.
 A compressed air of 6 kgf/cm.sup.2 was used as a pressurized fluid. The
 compressed gas was fed through fine openings (fluid-supply-openings)
 provided in a top surface of a cylindrical sintered copper 10 mm in
 diameter and 10 mm long. Three sintered coppers were buried in the
 slidable block so that their top surfaces could make a plane together with
 the top surface of the slidable block. The rear end of each sintered
 copper was connected with a gas path which led to a compressed gas
 supplying machine.
 When the clearance between the body of the male mold half and the female
 mold half was 30 mm, a molten polypropylene resin (Sumitomo Noblen BTA51E1
 manufactured by Sumitomo Chemical Co., Ltd.; temperature: 210.degree. C.)
 was supplied between the mold surfaces from a resin path provided in the
 male mold half. Almost at the same time when the predetermined amount of
 the resin completed to be supplied, the female mold was lowered until the
 clearance defined between the body and the female mold half became 3.5 mm
 to close the mold with a maximum clamping force of 100 tonf. Consequently,
 the resin was flowed to fill the cavity with the resin. See FIG. 2.
 The clamping force was maintained for 2 seconds at 100 tonf, followed by
 being reduced to 30 tonf. At the same time, injection of the compressed
 gas through the fluid-supply-openings and the movement of the slidable
 block were commenced. One second after the beginning of the movement of
 the slidable block, the female mold half was lifted to make the clearance
 between the body of the male mold half and the female mold half 10 mm.
 While the injection of the compressed air being continued, the resin was
 cooled to be solidified. See FIG. 3. After stopping the injection of the
 compressed gas, the mold was opened and a hollow molded article was taken
 out.
 A hollow space was formed throughout the hollow molded article obtained.
 The hollow molded article had good appearance without having any sink mark
 and blister.
 Example 2
 A hollow molded article in which a carpet was laminated on a resin
 substrate was produced according to a similar manner as described in
 Example 1 except that the carpet was supplied between the mold halves
 before the molten polypropylene resin was supplied between the mold
 halves.
 The hollow space was formed throughout the hollow molded article obtained.
 The hollow molded article had good appearance without having any sink mark
 and blister. The hair of the carpet was uniformly pressed.