JP2007203502A - Thermoplastic resin made molded product and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoplastic resin made molded product constituted by heat-sealing libs in part of a thermoplastic resin made foamed sheet and having good appearance and a producing method of the same. <P>SOLUTION: In the thermoplastic resin made molded product and the producing method of the same, the ribs 7 are heat-sealed to a part of the thermoplastic resin made foamed sheet 1, the shape of the ribs 7 satisfies 1 mm≤(V<SB>1</SB>/S<SB>1</SB>)≤9 mm, wherein V<SB>1</SB>is the volume (mm<SP>3</SP>) of the ribs and S<SB>1</SB>is the area (mm<SP>2</SP>) of the heat-sealed portions of the ribs. The thermoplastic resin made molded product is produced by supplying the softened thermoplastic resin made foamed sheet 1 between a shaping mold in whose shaping face recessed portions whose volume and area of opening portion satisfies 1 mm≤(V<SB>2</SB>/S<SB>2</SB>)≤9 mm, wherein V<SB>2</SB>is the volume of the recessed portion and S<SB>2</SB>is the area of the opening portion of the recessed portion, and a shaping mold which constitutes a pair along with the above shaping mold for shaping the ribs 7. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a thermoplastic resin molded article and a method for producing the same.

  Molded articles obtained by molding a thermoplastic resin foam sheet are excellent in light weight, recyclability, heat insulation, and the like, and thus are used in various applications such as automobile members and building materials. Particularly in applications where rigidity is required, a molded product in which a rib is partially provided on a foamed sheet is used. As a method for producing a molded product made of a thermoplastic resin in which ribs are fused to a part of such a foamed sheet, a partially molten thermoplastic resin is formed into a foamed laminated sheet formed into a predetermined shape. Is known, and a rib is shaped (see, for example, Patent Document 1).

JP 2003-231195 A

  The reinforcing effect by the ribs is more effective as the height of the ribs to be shaped is higher, that is, the larger the degree of protrusion from the foamed sheet. In order to obtain a thermoplastic resin molded product having a high rib by the method of Patent Document 1, it is necessary to increase the supply pressure of the molten thermoplastic resin for shaping the rib. However, when the supply pressure of the resin is increased, the pressure concentrates on the rib fused portion of the foam sheet, and the foam sheet is partially compressed, and the resulting molded product may have a poor appearance.

  The present invention provides a molded article made of a thermoplastic resin in which a rib is fused to a part of a foamed sheet made of a thermoplastic resin, and a molded article made of a thermoplastic resin having a good appearance and a method for producing the same. .

That is, the present invention relates to a thermoplastic resin molded product in which a rib is fused to a part of a thermoplastic resin foam sheet, and the shape of the rib satisfies the formula (A). is there.
1 mm ≦ (V ₁ / S ₁ ) ≦ 9 mm Formula (A)
V ₁ : rib volume (mm ³ )
S ₁ : Rib fused area (mm ² )
Moreover, this invention is a manufacturing method of the said thermoplastic resin molded product which a rib is fuse | melted to a part of thermoplastic resin foam sheet which includes the following processes in order.
(1) Step of heating and softening the foamed sheet made of thermoplastic resin (2) Mold A in which a concave portion whose volume and opening area satisfy the formula (B) is formed on the molding surface in order to shape the rib And a step of supplying the thermoplastic resin foam sheet obtained in the step (1) between the mold A and the mold B paired with the mold A 1 mm ≦ (V ₂ / S ₂ ) ≦ 9 mm Formula (B)
V ₂ : Volume of the recess (mm ³ )
S ₂ : Opening area of the recess (mm ² )
(3) The mold A and the mold B are closed, the thermoplastic resin foam sheet is shaped into a predetermined shape, and the opening of the recess formed on the molding surface of the mold A is made of the thermoplastic resin. Step 4 of closing with foam sheet (4) A molten thermoplastic resin is supplied to the concave portion through a resin passage provided in the mold A so as to communicate with the concave portion, and the molten thermoplastic resin and the thermoplastic resin foam are supplied. Step of fusing and integrating the sheet (5) Step of simultaneously opening or stopping the supply of the molten thermoplastic resin and then opening the mold to take out the molded product made of the thermoplastic resin

  The molded article made of the thermoplastic resin of the present invention is a molded article having a good appearance. Moreover, according to the method for producing a molded product of a thermoplastic resin of the present invention, a molded product of a thermoplastic resin having a good appearance can be obtained.

The present invention is a molded product made of a thermoplastic resin in which a rib is fused to a part of a foamed sheet made of a thermoplastic resin, and the molded product made of a thermoplastic resin in which the shape of the rib satisfies the formula (A). .
1 mm ≦ (V ₁ / S ₁ ) ≦ 9 mm Formula (A)
V ₁ : rib volume (mm ³ )
S ₁ : Rib fused area (mm ² )

Here, the volume of the rib is the volume of the rib when cut at the fused portion between the rib and the thermoplastic resin foam sheet, and the fused area of the rib is the area of the cut surface of the cut rib. is there. The volume V ₁ of the ribs, the ribs and the expanded sheet and the thermoplastic resin molded article of the fused portion area S ₁ is the invention which satisfies the formula (A) are not rib fused portion of the foam sheet is deformed It is a foamed product made of a thermoplastic resin with a good appearance. The position and the number of ribs in the thermoplastic resin molded article of the present invention are not particularly limited.

As for the rib in this invention, it is preferable that the height H and the fusion | melting part width W of this rib and a foam sheet satisfy | fill the following formula | equation (C).
0.5 ≦ (H / W) ≦ 2 Formula (C)
By making the rib shape satisfy the formula (C), a molded article made of a thermoplastic resin having a better appearance is obtained. The rib height H is the highest height from the cut surface of the rib cut from the foam sheet, and the fused portion width W is the shortest length between opposing sides in the cut surface. It is.

  The thermoplastic resin molded article of the present invention is obtained by fusing ribs to a part of a thermoplastic resin foam sheet. Although the thermoplastic resin foam sheet used in the present invention is not particularly limited, a foam sheet having a foaming ratio of 2 to 10 times and a thickness of about 1 to 10 mm is usually used. In addition, the thermoplastic resin foam sheet can be formed into a desired shape by a method such as vacuum forming, pressure forming, vacuum pressure forming, press forming or the like.

  Examples of the resin constituting the thermoplastic resin foam sheet used in the present invention include olefin homopolymers having 2 to 6 carbon atoms such as ethylene, propylene, butene, pentene, and hexene, and olefins having 2 to 10 carbon atoms. Olefin resins such as olefin copolymers obtained by copolymerizing two or more monomers selected from ethylene, ethylene-vinyl ester copolymers, ethylene- (meth) acrylic acid copolymers, ethylene- (meth) Examples include acrylic ester copolymers, ester resins, amide resins, styrene resins, acrylic resins, acrylonitrile resins, and ionomer resins. These resins may be used alone or in combination with a plurality of resins. Olefin resins are preferably used from the viewpoints of moldability, oil resistance, cost, etc., and propylene resins are particularly preferably used from the viewpoint of rigidity and heat resistance of the obtained molded product.

  Examples of the propylene resin include propylene homopolymers and propylene copolymers containing 50 mol% or more of monomer units derived from propylene. The copolymer may be any of a block copolymer, a random copolymer, and a graft copolymer. As an example of the propylene copolymer preferably used, a copolymer of ethylene or an α-olefin having 4 to 10 carbon atoms and propylene can be given. Examples of the α-olefin having 4 to 10 carbon atoms include 1-butene, 4-methylpentene-1, 1-hexene and 1-octene. The content of monomer units other than propylene in the propylene-based copolymer is preferably 15 mol% or less for ethylene and 30 mol% or less for α-olefins having 4 to 10 carbon atoms. One type of propylene resin may be used, or two or more types may be mixed and used.

By using 50% by weight or more of the thermoplastic resin constituting the foam layer of a long-chain branched propylene resin or a high molecular weight propylene resin having a weight average molecular weight of 1 × 10 ⁵ or more, a propylene resin foam having fine bubbles is used. A sheet can be obtained. Further, among such propylene resins, non-crosslinked propylene resins are preferably used because gels are unlikely to occur during sheet recycling.

Here, the long-chain branched propylene-based resin refers to a propylene-based resin having a degree of branching index [A] satisfying 0.20 ≦ [A] ≦ 0.98.
An example of a long-chain branched propylene-based resin satisfying the branching index [A] of 0.20 ≦ [A] ≦ 0.98 is propylene PF-814 manufactured by Basel.

The degree of branching index indicates the degree of long chain branching in a polymer, and is a numerical value defined in the following formula.
Branch index [A] = [η] _Br / [η] _Lin
Here, [η] _Br is the intrinsic viscosity of the propylene resin having a long chain branch, and [η] _Lin is a straight chain having the same monomer unit and the same weight average molecular weight as the propylene resin having the long chain branch. It is an intrinsic viscosity of a chain propylene resin.
Intrinsic viscosity, also called intrinsic viscosity, is a measure of the ability of a polymer to enhance solution viscosity. Intrinsic viscosity depends in particular on the molecular weight of the polymer molecules and the degree of branching. Therefore, by comparing the intrinsic viscosity of a polymer having long chain branches with the intrinsic viscosity of a linear polymer having the same weight average molecular weight as that of the polymer having long chain branches, the degree of branching of the polymer having long chain branches can be determined. It can be a scale. The method for measuring the intrinsic viscosity of a propylene-based resin is described by Elliott et al. [J. Appl. Polym. Sci. , 14, 2947-2963 (1970)], for example, a propylene resin is dissolved in tetralin or orthodichlorobenzene, and the intrinsic viscosity at 135 ° C. Can be measured.
The weight average molecular weight (Mw) of the propylene-based resin can be measured by various commonly used methods. L. The method disclosed by McConnel in American Laboratory, May, 63-75 (1978), that is, a low-angle laser light scattering intensity measurement method is particularly preferably used.
As an example of a method for polymerizing a high molecular weight propylene resin having a weight average molecular weight of 1 × 10 ⁵ or more, as described in JP-A No. 11-228629, a high molecular weight component is first polymerized, followed by low molecular weight. Examples thereof include a method of polymerizing components.

Among long-chain branched propylene resins or high-molecular-weight propylene resins, propylene resins having a uniaxial melt-extension viscosity ratio η ₅ / η _0.1 measured under the following conditions at around melting point + 30 ° C. are preferably 5 or more, more preferably 10 or more resins. The uniaxial melt extensional viscosity ratio is a value measured using an apparatus such as a uniaxial extensional viscosity measurement apparatus (for example, a uniaxial extensional viscosity measurement apparatus manufactured by Rheometrics, Inc.) at an elongation strain rate of 1 sec ⁻¹ . the uniaxial melt elongation viscosity after 0.1 seconds from the strain initiation and eta _0.1, the uniaxial melt elongation viscosity after 5 seconds and eta _5. By using a propylene-based resin having such uniaxial extensional viscosity characteristics, a foam sheet having finer bubbles can be produced.

  The foaming agent used in producing the thermoplastic resin foam sheet may be either a so-called chemical foaming agent or a physical foaming agent, or a combination thereof. Examples of the chemical foaming agent include a thermal decomposition type foaming agent that decomposes to generate nitrogen gas (azodicarbonamide, azobisisobutyronitrile, dinitrosopentamethylenetetramine, p-toluenesulfonylhydrazide, p, p'- Oxy-bis (benzenesulfonyl hydrazide) and the like, and pyrolytic inorganic foaming agents that decompose to generate carbon dioxide (sodium hydrogen carbonate, ammonium carbonate, ammonium bicarbonate, etc.) . Specific examples of the physical foaming agent include propane, butane, water, carbon dioxide gas, and the like. Among the foaming agents exemplified above, a pyrolytic foaming agent is particularly preferably used because it is easy to handle, and a mixture of azodicarbonamide and sodium hydrogencarbonate is particularly preferred because it is easy to form a foam sheet having a high expansion ratio. Used. As a method of blending the foaming agent into the resin constituting the foamed sheet, the resin pellets and the foaming agent master batch pellet are dry blended, then supplied to the extruder, the resin is plasticized in the extruder, and the resin is discharged from the die outlet. A method of forming a foamed sheet by foaming while extruding is preferably used. The amount of the foaming agent used is appropriately selected according to the type of foaming agent and resin used so that a desired foaming ratio can be obtained. 20 parts by weight.

  The method for producing the thermoplastic resin foam sheet is not particularly limited, but a sheet obtained by extrusion molding using a flat die (T-die) or a circular die is preferable, and the resin melted from the circular die is foamed. However, a method of stretching and cooling along extrusion, mandrels and the like is particularly preferably used. When the foamed sheet is produced by extrusion molding, the molten resin can be extruded from a die and solidified by cooling and then stretched. The foamed sheet may be a single layer or a multilayer, but from the viewpoint of preventing foam breakage during sheet production, a multilayered foam sheet having non-foamed layers in both outer layers is preferred. As the resin constituting the non-foamed layer, those described above as examples of the resin constituting the foamed layer can be used, but the same type of resin as that constituting the foamed layer is preferable. In the case of a propylene-based resin, the non-foamed layer is also preferably composed of a propylene-based resin. The thickness of the non-foamed layer is preferably 1 to 10% of the foamed layer, and is preferably 2 to 5% from the balance between lightness and rigidity.

The thermoplastic resin foam sheet used in the present invention may be a composite sheet obtained by laminating a single layer or multilayer foam sheet and other materials. Such a composite sheet is obtained by laminating a foam sheet and another material by dry lamination, sand lamination, hot roll bonding, hot air bonding, or the like.
Examples of other materials laminated with the foam sheet include woven fabric, nonwoven fabric, sheet, film, foam, and net-like material. These materials include thermoplastic resins such as olefin resins, vinyl chloride resins, and styrene resins, rubbers such as polybutadiene and ethylene-propylene copolymers, thermoplastic elastomers, and cellulose fibers such as cotton, hemp, and bamboo. Can be mentioned. These materials may be provided with an uneven pattern such as a texture, printed or dyed, and may be a single layer or a multilayer.

  As the thermoplastic resin forming the rib in the present invention, the same resin as the resin forming the thermoplastic resin foam sheet can be used. Olefin resins are preferably used from the viewpoints of moldability, oil resistance, cost, and the like, and propylene resins are particularly preferably used from the viewpoint of rigidity, heat resistance, and the like. When a propylene-based resin is used, a resin having a melt flow rate of about 50 to 300 g / 10 min is preferably used from the viewpoint of the fluidity of the resin during molding and the strength of the shaped rib.

  The thermoplastic resin foam sheet or rib of the present invention may contain an additive. Examples of the additive include a filler (filler), an antioxidant, a light stabilizer, an ultraviolet absorber, a plasticizer, an antistatic agent, a colorant, a release agent, a fluidity-imparting agent, and a lubricant. Specific examples of the additive include inorganic fibers such as glass fibers and carbon fibers, inorganic particles such as talc, clay, silica, titanium oxide, calcium carbonate, and magnesium sulfate. Among these, it is preferable to mix about 5 to 30 wt% of talc, glass fiber, etc. from the viewpoint of improving the strength of the foamed sheet or rib and reducing the shrinkage rate during molding.

As a manufacturing method of the thermoplastic resin molded article of the present invention, a manufacturing method including the following steps in order is mentioned.
(1) Step of heating and softening the foamed sheet made of thermoplastic resin (2) Mold A in which a concave portion whose volume and opening area satisfy the formula (B) is formed on the molding surface in order to shape the rib And a step of supplying the thermoplastic resin foam sheet obtained in the step (1) between the mold A and the mold B paired with the mold A 1 mm ≦ (V ₂ / S ₂ ) ≦ 9 mm Formula (B)
V ₂ : Volume of the recess (mm ³ )
S ₂ : Opening area of the recess (mm ² )
(3) The mold A and the mold B are closed, the thermoplastic resin foam sheet is shaped into a predetermined shape, and the opening of the recess formed on the molding surface of the mold A is made of the thermoplastic resin. Step 4 of closing with foam sheet (4) A molten thermoplastic resin is supplied to the concave portion through a resin passage provided in the mold A so as to communicate with the concave portion, and the molten thermoplastic resin and the thermoplastic resin foam are supplied. Step of fusing and integrating the sheet (5) Step of simultaneously opening or stopping the supply of the molten thermoplastic resin and then opening the mold to take out the molded product made of the thermoplastic resin

  In the method for producing a thermoplastic resin molded product, a molding die A having a molding surface formed with recesses corresponding to the shape and number of ribs to be shaped, and a molding die B that forms a pair with the molding die A And are used. The recess provided in the mold A satisfies the formula (B). A resin passage for supplying molten thermoplastic resin to the recess is provided in the mold having the recess. The molten thermoplastic resin can be supplied at a low pressure by supplying the molten thermoplastic resin to the recess satisfying the formula (B) from the resin passage, so that the deformation of the thermoplastic resin foam sheet is suppressed. And a molded article made of a thermoplastic resin having a good appearance can be obtained. One of the molds A and B may be a male mold and the other a female mold, both may be female molds, or both may be plate-shaped molds. Moreover, the recessed part for shaping a rib may be formed also in the molding surface of the shaping | molding die B. FIG.

  The material of the mold is not particularly limited, but is usually made of metal from the viewpoint of dimensional stability and durability, and is preferably made of aluminum or stainless steel from the viewpoint of cost and light weight. Moreover, it is preferable that a shaping | molding die is a structure which can adjust temperature with a heater, a heat medium, etc. The molding die preferably has a molding surface of 30 to 80 ° C., more preferably 50 to 60 ° C. during molding.

Hereinafter, an example of a method for producing a thermoplastic resin molded article of the present invention will be described with reference to FIG. FIG. 1- (1) shows a heat-softened foam sheet made of a thermoplastic resin, a flat plate-shaped mold A in which concave portions having a shape satisfying the formula (B) are formed on the molding surface, and a flat plate-shaped mold B The process (2) which supplies a thermoplastic resin foam sheet is shown.
FIG. 1- (2) shows a step (3) in which the mold A and the mold B are closed and the thermoplastic resin foam sheet is shaped into a predetermined shape. Examples of the method for shaping the thermoplastic resin foam sheet include vacuum forming, pressure forming, vacuum / pressure forming, and press forming. Since complex shapes can be easily formed, vacuum forming, pressure forming, and vacuum / pressure forming are particularly preferably applied. When the thermoplastic resin foam sheet is shaped by these methods, a mold that can be vacuum-sucked or supplied with compressed air from its molding surface is used as at least one of the molds A and B. Specifically, the mold A can be vacuumed, both the molds A and B can be vacuumed, the mold B can be supplied with compressed air, the mold A can be vacuumed, and the mold B can be compressed air. Can be supplied. Examples of the mold capable of vacuum suction or supply of compressed air include a mold in which at least a part of the molding surface of the molding die is made of a sintered alloy, a mold in which holes are provided in at least a part of the molding surface, and the like. It is done. The number and position of holes provided in the mold and the hole diameter are not particularly limited.

  When forming a thermoplastic resin foam sheet by vacuum molding, vacuum suction is started from the molding surface at the same time when the mold is closed or after the mold is closed, and the thermoplastic foam sheet is applied to the molding surface. Adhere to a predetermined shape. Vacuum suction may be performed only from the mold A or from both molds. When vacuum suction is performed from both molds, the vacuum suction may be started simultaneously, or the vacuum suction may be started first from either one. When vacuum suction is performed from both molds, the molds may be opened while maintaining a state in which the molding surfaces of the molds and the thermoplastic resin foam sheet are in close contact with each other. By this method, a molded article made of a thermoplastic resin having a high expansion ratio can be obtained. The mold opening may be performed after supplying the molten thermoplastic resin to the recess or while supplying the molten thermoplastic resin. The degree of vacuum suction is not particularly limited, but vacuum suction is preferably performed so that the degree of vacuum between the mold and the foamed sheet is −0.05 to 0.1 MPa. The degree of vacuum is the pressure between the mold and the foam sheet with respect to atmospheric pressure. That is, “the degree of vacuum is −0.05 MPa” indicates that the pressure between the mold and the foamed sheet with respect to atmospheric pressure is 0.95 MPa. The degree of vacuum of the pressure between the mold and the foamed sheet with respect to atmospheric pressure is measured in a vacuum suction passage in the mold.

When a thermoplastic resin foam sheet is shaped into a predetermined shape by pressure forming, compressed air is supplied so that the pressure between the mold B and the thermoplastic resin foam sheet is about 2 to 5 MPa. It is preferable to do. The degree of pressurization between the mold A and the thermoplastic resin foam sheet is a pressure measured in the compressed air supply passage in the mold.
In FIG. 1- (2), since the thermoplastic resin foam sheet is formed in contact with the molding surface of the mold by closing the mold, the opening of the recess provided in the molding surface of the mold is the thermoplastic resin foam sheet. It will be in the state blocked by.

  FIG. 1- (3) shows a state where molten thermoplastic resin is supplied to the concave portion through a resin passage provided in the mold A so as to communicate with the concave portion, and the molten thermoplastic resin and the thermoplastic resin foam sheet are supplied. (4). As the molten thermoplastic resin has a lower resin pressure at the time of supply, the appearance of the thermoplastic resin foam sheet is less likely to occur during fusion. The maximum pressure in the mold cavity of the molten thermoplastic resin is preferably 5 MPa or less, and when the molten thermoplastic resin is supplied, the molten thermoplastic resin leaks from the contact surface between the mold and the thermoplastic resin foam sheet. In order to reduce appearance defects due to the occurrence of burrs, the pressure is more preferably 3 MPa or less. When the thermoplastic resin foam sheet is formed by vacuum forming in the step (3), the vacuum suction may be continued when the molten passion plastic resin is supplied to the recesses in the step (4). FIG. 1- (3) shows a state in which a molten thermoplastic resin and a thermoplastic resin foam sheet are fused and integrated.

The step (5) is a step of taking out the thermoplastic resin foam molded product by opening the mold simultaneously with or after stopping the supply of the molten thermoplastic resin. FIG. 1- (4) shows a state where the mold is opened.

  The molded product of the thermoplastic resin of the present invention can be used for packaging materials such as food containers, automobile interior parts, building materials, and home appliances. Examples of automobile interior parts include door trims, ceilings, and trunk sides.

EXAMPLES Hereinafter, although this invention is demonstrated based on an Example, this invention is not limited to an Example at all.
[Example 1]

A molded product made of a thermoplastic resin was produced by a method shown in FIG. 1 using a polypropylene foam sheet (product name: Sumiceller Foam PP sheet manufactured by Sumika Plustech) having a foaming ratio of 3 times and a thickness of 3 mm.
Recessed portion (5) for forming ribs (as shown in FIG. 2, recessed portion opening thickness (9) 5 mm, anti-opening portion thickness (10) 4 mm, height (11) 5 mm, length (12) 370 mm) , Volume (13) 8325 mm ³ , recess opening area (14) 1850 mm ² in shape) on the molding surface, and mold B (6) that can be shaped into a flat plate shape. Using a pair of molds, a flat plate having ribs was formed. The molding die A is provided with a resin passage (4) capable of supplying a molten thermoplastic resin so as to communicate with the concave portion, and is provided with a molten thermoplastic resin pressure measuring sensor in the vicinity of the concave portion of the resin passage. It was a type. Mold A (3) was used with its temperature adjusted to 60 ° C.
While the thermoplastic resin foam sheet (1) is fixed to the clamp frame (2) of a vacuum forming machine (VAIM0301 manufactured by Sato Tekko Co., Ltd.) equipped with an extruder, the upper surface of the sheet becomes 190 ° C. by a near infrared heater. Was softened by heating. The foam sheet (1) softened by heating was supplied between the mold A (3) and the mold B (6) in a state of being fixed by the clamp frame (2).
Next, the mold A (3) and the mold B (6) were closed, and formed into a flat thermoplastic resin molded product having a thickness of 2.8 mm by press molding.
Propylene-based resin (manufactured by Sumitomo Chemical Co., Ltd., Nobrene BUE81E6, MFR = 80 g / min) is supplied to the concave portion of the mold at 3 g / sec through the resin passage (4) in the mold A (3) for 2.5 seconds. The concave portion was filled with a molten thermoplastic resin. After cooling the molded product by blowing air from a cooling fan, the mold was opened and the molded product was taken out. Unnecessary end portions were cut to obtain a flat plate (8) having ribs (7) as shown in FIG. The obtained flat plate having ribs had good appearance.

[Comparative Example 1]
In Example 1, the shape of the recesses for forming the ribs is different (the recess opening thickness is 2.5 mm, the counter opening thickness is 2 mm, the height is 15 mm, the length is 370 mm, the volume is 12488 mm ³ , and the opening area of the recess is 925 mm ^2. ₎ using the mold a, except that supplying 3.8 seconds molten thermoplastic resin with 3 g / sec into the mold recess, to produce a flat plate having a rib in the same manner as in example 1.
In the obtained flat plate having ribs, the molten thermoplastic resin entered the foamed sheet made of thermoplastic resin, and a raised appearance defect occurred on the side opposite to the rib surface.

Schematic of an example of the manufacturing method of the thermoplastic resin molded article of the present invention Plan view of mold A of Example 1 Sectional drawing of the shaping | molding die of Example 1 (thing which cut | disconnected the metal mold | die recessed part of FIG. 2 in the (a) direction) Plan view of flat plate with ribs Sectional drawing of the flat plate which has the rib obtained in Example 1 (what cut | disconnected the rib part of FIG. 4 in the (b) direction)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermoplastic resin foam sheet 2 Clamp frame 3 Mold A
4 Resin passage 5 Recess 6 Mold D
7 Rib 8 Molded product made of thermoplastic resin (flat plate)
9 Mold Opening A Recess Thickness 10 Mold A Recessed Opening Thickness 11 Mold D Recess Height 12 Mold A Recess Length 13 Mold D Recess Volume

Claims (2)

A molded product made of a thermoplastic resin in which a rib is fused to a part of a foamed sheet made of a thermoplastic resin, and the molded product made of a thermoplastic resin satisfying the formula (A) 1 mm ≦ (V ₁ / S ₁ ) ≦ 9 mm Formula (A)
V ₁ : rib volume (mm ³ )
S ₁ : Rib fused area (mm ² ) The method for producing a molded product of a thermoplastic resin according to claim 1, wherein the rib is fused to a part of the foamed sheet made of a thermoplastic resin, including the following steps in order.
(1) Step of heating and softening the foamed sheet made of thermoplastic resin (2) Mold A in which a concave portion whose volume and opening area satisfy the formula (B) is formed on the molding surface in order to shape the rib And a step of supplying the thermoplastic resin foam sheet obtained in the step (1) between the mold A and the mold B paired with the mold A 1 mm ≦ (V ₂ / S ₂ ) ≦ 9 mm Formula (B)
V ₂ : Volume of the recess (mm ³ )
S ₂ : Opening area of the recess (mm ² )
(3) The mold A and the mold B are closed, the thermoplastic resin foam sheet is shaped into a predetermined shape, and the opening of the recess formed on the molding surface of the mold A is made of the thermoplastic resin. Step 4 of closing with foam sheet (4) A molten thermoplastic resin is supplied to the concave portion through a resin passage provided in the mold A so as to communicate with the concave portion, and the molten thermoplastic resin and the thermoplastic resin foam are supplied. Step of fusing and integrating the sheet (5) Step of simultaneously opening or stopping the supply of the molten thermoplastic resin and then opening the mold to take out the molded product made of the thermoplastic resin

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