JP2000065287A - Heat insulating mold body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve adaptability of a recycle, a heat insulating property, and chemical resistance by filling a foam made of non-crosslinked polypropylene base resin into an incrustation made of polypropylene base resin, and specifying a melt flow rate of each polypropylene base resin and a melting point difference between them. SOLUTION: A heat insulating mold body adapted to a door such as a refrigerator is formed by filling a foam 2 made of a substantially non-crosslinked polypropylene base resin into an incrustation 1 made of a polypropylene base resin. A ratio of melt flow rate(MFR) between each polypropylene base resin for forming the incrustation 1 and the foaming body 2 may be within 0.2 to 5, and thereby, a mechanical property of a mold body can be improved, and molding failure can be prevented. A difference in melting point among each polypropylene resin may be not more than 25 deg.C, and thereby, rigidity and strength are ensured when the molding body is re-molded so as to expand an use for a recycle material. It is thus possible to improve adaptability of a recycle in the heat insulating molding body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-insulated molded article having excellent recyclability, excellent heat-insulating properties and chemical resistance, and useful for applications such as refrigerator doors.

[0002]

2. Description of the Related Art Conventionally, an outer shell constituting an outer structural portion and a heat-insulated molded article in which a heat insulating material is embedded are used for, for example, refrigerator doors. Specifically, the refrigerator door includes an outer plate formed by forming a steel plate and a resin cap member covering the upper and lower ends of the outer plate, as seen in Japanese Patent Application Laid-Open No. 5-99561. A heat insulating structure in which a heat insulating material made of rigid urethane foam or the like is embedded in an outer shell is shown. In addition, a resin inner plate generally having a function as an inner pocket is attached to the opposite surface of the outer plate, and a rubber packing for maintaining the close contact between the refrigerator body and the door is provided.

In recent years, Japanese Patent Application Laid-Open No. 5-322438
As disclosed in Japanese Patent Application Laid-Open Publication No. H11-264, a refrigerator door using an ABS resin, a polystyrene resin, or the like as a material of the outer plate has been used. By forming the outer plate of resin, a complicated shape can be easily obtained by a molding method such as an injection molding method, and a cap member and the like can be integrally molded, so that a refrigerator door excellent in productivity and design can be obtained. It has become possible to obtain a heat-insulating molded body to be used.

[0004]

However, the conventional refrigerator door using metal as the material of the outer plate requires a metal outer plate and a heat insulating material made of rigid urethane foam when the material is reused. However, it is indispensable to separate and disassemble members such as resin inner plates, and it is difficult to reuse hard urethane foam as a heat insulating material. Therefore, disposal methods are limited to incineration and landfill. There was.

[0005] Further, in a door in which a resin is used as the outer plate material and the cap portion is integrally formed, the separation and disassembly work is not only complicated because the outer plate and the hard urethane foam have high adhesiveness, but also the outer plate is difficult. It is difficult to completely separate the material and the rigid urethane foam, and when the outer plate material is pulverized and reused to form a molded product, the rigid urethane foam is mixed and the mechanical properties and product appearance are deteriorated. Large and reusable applications are severely limited.

[0006] For these reasons, heat-insulated molded articles such as refrigerator doors are largely reclaimed without being reused, and thus pose a major environmental problem.

[0007] In addition, a conventional refrigerator door using a resin outer panel requires surface treatment such as painting in order to prevent deterioration of the surface when cleaned with a detergent or the like. for that reason,
The productivity is reduced by the coating process, and a coating film separation process is required at the time of reuse, which has been an obstacle to the reuse of the outer plate material.

[0008] In order to facilitate the reuse of the refrigerator door,
JP-A-6-147740 proposes a method for improving workability of dismantling by using a material having low adhesion to hard urethane foam as a material of an outer plate, but completely solves the above-mentioned problems. Has not been reached.

Therefore, an object of the present invention is to make it possible to reuse most of the materials and to make the process for recycling very simple.
An object of the present invention is to provide a heat-insulated molded article useful as a door of a refrigerator or the like.

[0010]

Means for Solving the Problems The present inventors have conducted intensive studies on the above-mentioned problems, and as a result, a foam made of a specific polypropylene resin as a heat insulating material was placed inside a shell made of a polypropylene resin. It has been found that the filled heat-insulating molded body can solve all of the above problems, and has completed the present invention.

That is, the present invention is a heat-insulating molded article characterized in that a substantially non-crosslinked polypropylene resin foam is filled in an outer shell made of a polypropylene resin.

The heat-insulated molded article of the present invention is capable of obtaining a crushed piece that can be reused as a molded article by being put into a crusher or the like without performing an operation of separating and disassembling the outer shell and the foam. Can be.

That is, a molded article obtained by melt-molding the pulverized piece has little deterioration in mechanical properties and good appearance, so that it has been very difficult in the past to use daily necessities, home appliances and automobiles. It can be reused for parts.

Therefore, it can be said that the heat-insulated molded article of the present invention has extremely high adaptability to recycling as compared with a conventional heat-insulated molded article known as a door of a refrigerator or the like.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A typical embodiment of a heat-insulated molded article of the present invention is shown in FIGS. As shown in FIG. 1, the heat-insulated molded article of the present invention is constituted by filling a foam 2 made of a substantially non-crosslinked polypropylene resin into an outer shell 1 made of a polypropylene resin.

The shape of the outer shell is not particularly limited as long as it can contain the foam. For example, a box-shaped body having an open surface as shown in FIG. 1 or a closed hollow box-shaped body as shown in FIG. 2 is generally used.

FIG. 3 is a perspective view showing a typical structure in which the heat insulating molded article of the present invention is applied to a refrigerator door. That is, an outer plate 3 constituting the outer shell 1 is used, and a foam 5 made of a substantially non-crosslinked polypropylene resin is filled therein, and the inner plate 4 is combined therewith, and further adhered to the refrigerator body. A refrigerator door is formed by assembling a packing 6 for preventing cold air from leaking out of the refrigerator.

In general, the outer plate of a refrigerator door has a box shape, and has a handle at the top for hanging a hand when the door is opened and closed. The dimensions of the outer plate of the refrigerator door are not particularly limited, but are preferably 500 to 1000 mm in height and 400 to 800 in width.
mm, thickness 30-100mm, thickness of outer plate 2-7m
m. Further, it is preferable to provide a rib portion on the back surface side of the front plate of the outer plate for the purpose of improving product strength.
The shape and size of the rib portion are not particularly limited, but the thickness of the rib is preferably 0.25 to 1 times the thickness of the outer plate, and the height of the rib is preferably 0.5 to 4 times the thickness of the outer plate. .

Here, the material forming the inner plate 4 of the door is not particularly limited, but by using the same kind of polypropylene resin as the outer plate 3, the whole can be constituted as the outer shell 1 and reused. In this case, the disassembly step can be further omitted, which is preferable.

Although the material of the packing 6 is not particularly limited, it is preferable to use a molded article made of an olefin-based elastomer as the packing because the step of removing the packing can be omitted, and the door can be easily reused.

In the present invention, as the polypropylene resin constituting the outer shell, known resins can be used without limitation. For example, a polymer containing propylene as a main component such as a propylene homopolymer, a propylene ethylene random copolymer, a propylene ethylene block copolymer, and a propylene butene random copolymer can be used.

The flowability of the polypropylene resin constituting the outer shell is not particularly limited, but is considered to be melt flow rate (hereinafter abbreviated as MFR) in consideration of moldability, rigidity and impact resistance. Is 3 to 80 g / 10 minutes (mi
n) is preferred. Here, this melt flow rate has a cylinder temperature of 2 according to JIS K7210.
The value at 30 ° C.

As the polypropylene resin constituting the outer shell, an isotactic pentad fraction of a boiling heptane-insoluble portion used as an index of the crystallinity of polypropylene is preferably 0.97% or more, more preferably 0.1% or more. 9
It is preferable to use 75 or more because a heat-insulated molded article having excellent chemical resistance and scratch resistance can be obtained, and in particular, the refrigerator door can be obtained.

Here, the isotactic pentad fraction of the boiling heptane-insoluble portion refers to the boiling heptane-insoluble portion of polypropylene as defined by A.I. The method was announced by Zambelli et al (Macromolecules 6 9
25 1973) means the value obtained by measuring the fraction of propylene monomer units at the center of a chain in which five propylene monomer units are consecutively meso-bonded in pentad units in a polypropylene molecule.

In the present invention, the proportion of the boiling heptane-insoluble portion in the total polymer is preferably 80% by weight or more, more preferably 85% by weight or more.

In the present invention, the boiling heptane-insoluble portion of the polypropylene resin is obtained by completely dissolving the resin in boiling xylene, lowering the temperature to 20 ° C., allowing the resin to stand still, and then separating and filtering. Is a extraction residue obtained by performing boiling heptane extraction in a Soxhlet extraction tube for 12 hours after drying.

In the present invention, the polypropylene resin having such properties may be obtained by any method. Generally, it is a Ziegler-Natta type stereospecific catalyst, and a catalyst comprising a titanium compound supported on magnesium chloride or a titanium trichloride compound and an organic aluminum compound is used.

As the titanium compound, a known compound used for polymerization of olefin is employed without any limitation.
In particular, a titanium compound containing titanium, magnesium and halogen as components and having a high catalytic activity and capable of obtaining a highly crystalline polymer is preferable. Examples of such a titanium compound include titanium halides, particularly titanium tetrachloride supported on various magnesium compounds. As a method for producing this catalyst, a known method is employed without any limitation. For example, a method of co-grinding titanium tetrachloride with a magnesium compound such as magnesium chloride, alcohol, ether,
Examples thereof include a method of co-grinding a titanium halide and a magnesium compound in the presence of an electron donor such as an ester, a ketone or an aldehyde, and a method of contacting a titanium halide, a magnesium compound and an electron donor in a solvent.

Next, as the organoaluminum compound,
Known compounds used for olefin polymerization can be used without any limitation. For example, alkyl aluminums such as trimethyl aluminum, triethyl aluminum and tri-n-propyl aluminum; and halogen-containing alkyl aluminums such as ethyl aluminum sesquichloride and diethyl aluminum chloride can be used.

Further, in order to enhance the crystallinity of the obtained polymer, it is preferable to use an electron donor in addition to the titanium compound and the organoaluminum compound. Examples of the electron donor include ether, amine, amide, sulfur-containing compound, nitrile, carboxylic acid, acid amide, acid anhydride, acid ester, and organosilicon compound. Of these, organosilicon compounds are most preferred.

The polymerization may be carried out in either the gas phase or the liquid phase. The polymerization may be carried out in an inert liquid or an inert solvent with respect to the catalyst.The polymerization may be carried out by introducing hydrogen during polymerization, or the obtained polymer may be prepared by a molecular weight regulator such as an organic peroxide. Degraded ones may be used. Further, the polymerization can be carried out by any of batch, semi-batch and continuous methods.

The polymerization conditions are not particularly limited as long as the effects of the present invention are recognized, and known conditions can be employed. For example, the polymerization temperature is 20-200 ° C., preferably 5
The range is 0 to 150 ° C. Further, the polymerization can be carried out in two or more stages under different conditions.

In the present invention, the above-mentioned polypropylene resin constituting the outer shell may be used by mixing with other resins within a range that does not significantly impair the effects of the present invention. Such other resins include ethylene, 1-butene, 1-pentene,
Homopolymers of α-olefins such as 4-methylpentene-1 or block copolymers or random copolymers of these α-olefins and propylene are preferred. In this case, such other resin is suitably blended in a proportion of 20 parts by weight or less, preferably 10 parts by weight or less based on 100 parts by weight of the polypropylene resin. When a resin composition obtained by mixing another resin in the above ratio is used as a material for the outer shell of the heat-insulated molded article of the present invention, the resin composition preferably has a boiling heptane-insoluble content of 80% by weight. , 85% by weight or more.

It is preferable that a nucleating agent is added to the polypropylene resin constituting the outer shell of the present invention in order to further improve the scratch resistance. Known nucleating agents can be used without any limitation. Specifically, metal carboxylate such as aluminum benzoate, potassium benzoate, sodium benzoate, lithium benzoate, Al-p-butyl benzoate, sodium β-naphthoate, sodium cyclohexanecarboxylate, sodium cyclopentanecarboxylate, etc. -Based compound: sodium bis (4-t-butylphenyl) phosphate, lithium bis (4-t-butylphenyl) phosphate, aluminum bis (4-t-butylphenyl) phosphate, bis (4-t -Butylphenyl) phosphate, magnesium bis (4-t-butylphenyl) phosphate, sodium 2,2′-methylene-bis (4,6-di-t-butylphenyl) phosphate, 2,2 ′ -Methylene-bis (4,6-di-t
-Butylphenyl) phosphate, aluminum 2,2′-methylene-bis (4,6-di-t-butylphenyl) phosphate, 2,2′-methylidene-bis (4,6
-Di-t-butylphenyl) phosphate calcium salt, 2,
Magnesium 2'-methylidene-bis (4,6-di-t-butylphenyl) phosphate, 2,2'-ethylidene-
Bis (4,6-di-t-butylphenyl) phosphate sodium salt, 2,2′-ethylidene-bis (4,6-di-t
-Butylphenyl) phosphate lithium, 2,2'-ethylidene-bis (4,6-di-t-butylphenyl) phosphate aluminum salt, bis- (4-t-butylphenyl)
Aromatic metal phosphate compounds such as calcium phosphate and magnesium bis- (4-t-butylphenyl) phosphate; dibenzylidenesorbitol, 1.3, 2.4-
Di (methylbenzylidene) sorbitol, 1.3, 2.
4-di (ethylbenzylidene) sorbitol, 1.3
2.4-di (butylbenzylidene) sorbitol, 1.
3,2.4-di (methoxybenzylidene) sorbitol, 1.3,2.4-di (ethoxybenzylidene) sorbitol, 1.3-chlorobenzylidene, 2.4-methylbenzylidenesorbitol, mono (methyl) dibenzylidenesorbitol And the like; and inorganic compounds such as silica, titanium dioxide, carbon black, fine powder talc, mica, alum, and pigments. Of these, Al-pt-butyl benzoate, 2,2'-methylene-bis (4,6-
The use of a metal salt of di-t-butylphenyl) phosphate or the like is most preferable in improving the scratch resistance of the outer shell.

The above nucleating agents may be used alone or in combination of two or more.

In the present invention, the compounding amount of the nucleating agent is
0.01 parts by weight based on 100 parts by weight of the polypropylene resin
To 3.0 parts by weight, of which 0.05 to 1.0 part by weight.
0 parts by weight is particularly preferred.

The polypropylene resin constituting the outer shell of the heat-insulating molded article of the present invention contains talc,
An inorganic filler such as wollastonite, barium sulfate, calcium carbonate, and glass may be blended. Here, two or more fillers may be used in combination. The amount of the inorganic filler is preferably 0.1 to 100 parts by weight based on 100 parts by weight of the polypropylene resin.

Further, the polypropylene resin constituting the outer shell is further added to the extent that the effects of the present invention are not impaired.
Various additives can be appropriately blended. Specifically, phenol-based, organic phosphite-based, organic phosphorus-based antioxidants such as phosphite, thioether-based antioxidants; hindered amine-based heat stabilizers; benzophenone-based, benzotriazole-based, benzoate-based ultraviolet absorbers, etc. ;
Nonionic, cationic, anionic and other antistatic agents;
Dispersants such as bisamides, waxes, and organic metal salts;
Chlorine scavengers such as carboxylate-based and hydrotalcite-based alkaline earth metal salts; lubricants such as amide-based, wax-based, organic metal salt-based, and ester-based; decomposers such as oxide-based and hydrotalcite-based; Metal deactivators such as hydrazines and amines; flame retardants such as brominated organics, phosphoric acid, antimony trioxide, magnesium hydroxide, and red phosphorus; organic pigments; inorganic pigments; foaming agents; Inorganic and organic antibacterial agents such as ionic ones, and the like.

In the present invention, the above components can be blended by any ordinary method which is carried out by mixing resins. For example, a method in which an additive component is added to a powdery or pelletized polypropylene resin, mixed with a tumbler, a Henschel mixer, or the like, and then melt-kneaded with an extruder to form pellets or the like is preferable. The order of addition of each component is not particularly limited, and each component may be mixed in a different order from the above method. Furthermore, a masterbatch in which each component is concentrated and blended at a high concentration can be prepared and mixed and used.

As a method of forming the outer shell of the heat-insulating molded body of the present invention, any method such as injection molding, press molding, extrusion molding, stampable molding, and blow molding may be employed. Usually, it is generally formed by injection molding. This injection molding may be performed by any method such as single-axis injection molding, multi-axis injection molding, injection compression molding, gas assist injection, gas compression injection molding, melt core molding, insert molding, core back molding, and two-color molding. However, gas-assisted injection molding, gas compression injection molding, injection compression molding, and the like are the most preferable in preventing deformation of a molded product from an anti-molded product.

As the polypropylene resin constituting the foam of the heat-insulating molded article of the present invention, a non-crosslinked polypropylene resin is used. When a foam made of a crosslinked polypropylene-based resin is used, the mechanical properties and appearance when the heat-insulated molded body is pulverized and formed into a molded product are greatly reduced, and the application for reuse is significantly limited. Here, "substantially non-crosslinked" means that when the polypropylene resin is subjected to Soxhlet extraction with boiling para-xylene for 12 hours, 1% by weight or more of the gel component does not remain.

The polypropylene resin constituting the foam in the heat-insulating molded article of the present invention is a propylene homopolymer,
Known materials such as a propylene-α olefin random copolymer such as a propylene ethylene random copolymer, a propylene ethylene block copolymer, and a propylene butene random copolymer can be used.

In order to achieve the object of the present invention, the ratio of the MFR of the polypropylene resin constituting the outer shell of the heat-insulating molded article to the MFR of the polypropylene resin constituting the foam is preferably 0.2 to 5, and more preferably 0.2 to 5. It is preferably from 0.3 to 3. When the heat-insulated molded body is pulverized and directly put into a hopper of an injection molding machine to form a molded article again, the mechanical properties of the molded article obtained by setting the MFR ratio within the above range, and bumps and gloss on the surface of the molded article. The effect of preventing molding defects such as unevenness is particularly excellent.

It is preferable that the difference between the melting point of the polypropylene resin forming the outer shell of the heat-insulating molded article and the melting point of the polypropylene resin forming the foam is 25 ° C. or less. If the difference in the melting points exceeds 25 ° C., the rigidity and strength tend to decrease when the heat-insulated molded body is pulverized and formed into a molded product again, so that the use of the recycled product may be limited.

As a method for obtaining a foam used in the molded article of the present invention, a known method can be used without any limitation. As an example, there is a method in which particles of a polypropylene-based resin which has been pre-expanded and further provided with an expanding ability are steam-heated in a mold or an outer shell set in the mold to foam and fuse. The method of prefoaming is described in JP-B-56-134.
A known method such as the method described in Japanese Patent Publication No. 4 can be adopted.
Also, a method of imparting foaming ability is described in JP-B-51-229.
A known method such as the method described in JP-A-51-51 can be employed.

The method of combining the outer shell and the foam is not limited at all. For example, the above-mentioned foam molding is performed by setting the outer shell and the inner plate in a mold and bringing the pre-foam into direct contact with the mold. And a method of separately performing foam molding in a mold and then incorporating the foam into the outer shell.

In order to obtain a good heat insulating effect, the expansion ratio of the foam used in the present invention is preferably 10 times or more, more preferably 20 times or more.

[0048]

According to the heat-insulating molded article of the present invention, an excellent molded article can be obtained even if the outer shell is recycled without separating it from the foam. For example, when the heat-insulated molded article of the present invention is used as a refrigerator door, it can be reused as a molded article by removing it from the main body at the time of disposal of the refrigerator, performing a simple separation and dismantling operation, and then putting it into a crusher or the like. Crushed pieces can be obtained. A molded product obtained by melting the above-mentioned crushed pieces has a very small reduction in mechanical properties and appearance even compared to a molded product made of a virgin polypropylene-based resin. The door can be said to be much easier to recycle than conventional ones.

Also, by using the heat-insulated molded article of the present invention for a heat-insulating member other than a refrigerator door, a product having extremely high recyclability can be manufactured by the same effect as that of the refrigerator door. .

The heat-insulated molded article of the present invention can be used not only as a refrigerator door, but also as a known heat-insulated molded article, for example, a heat insulating plate on the top, bottom, side and back of a refrigerator or freezer, or a cooler box. It can also be applied to heat-insulating walls of simple warehouses, doors and storage boxes for storage under floors, and interior materials for automobiles.

[0051]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

(1) The ratio of the boiling heptane-insoluble portion to the total polymer, and the isotactic pentad fraction of the boiling heptane-insoluble portion After completely dissolved in boiling xylene, the temperature was lowered to 20 ° C.
After standing for a while, the insoluble portion was separated and filtered, the insoluble portion was dried, and boiling heptane was extracted with a Soxhlet extraction tube for 8 hours. The dry weight of the obtained insoluble portion was measured, and the total polymer amount was measured. Was calculated. Next, the insoluble matter obtained by the above-mentioned operation was The method was announced by Zambelli et al (Macromolecules 6 9
25 1973), the fraction of propylene monomer units at the center of a chain of five meso-bonded propylene monomer units in pentad units in a polypropylene molecule was determined.

(2) Ethylene content Calculated using a chart of 13C-NMR spectrum. (3) MFR Measurement was performed at 230 ° C. according to JIS K7210.

(4) Melting point Using DSC6200R manufactured by Seiko Instruments, temperature rise rate condition is 10 ° C. / according to JIS K7122.
The melting point was measured in minutes.

(4) Foaming Ratio A part of the foam is cut out, and its specific gravity is measured.
The expansion ratio was measured.

(5) Measurement of mechanical properties Tensile rupture elongation: Measured at 23 ° C. according to JIS K7113.

Flexural modulus: Measured at 23 ° C. according to JIS K7203.

(6) Appearance The surface of the molded article was observed and evaluated according to the following three grades.

○: Almost no irregularities and uneven gloss were observed.

Δ: Slight unevenness or gloss unevenness is observed.

×: Many spots or gloss unevenness are observed.

(7) PP-1 The isotactic pentad fraction of the boiling heptane-insoluble portion is 0.980%, the proportion of the boiling heptane-insoluble portion in the total polymer is 96%, the MFR is 15 g / 10 min, and the melting point is 100 parts by weight of highly crystalline homopolypropylene at 164 ° C. was used as a base polymer, and 0.2 parts by weight of Al-p-butylbenzoate and tetrakis [methylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate) were added thereto. )] 0.04 parts by weight of methane, tris (2,4-di-t)
-Butylphenyl) phosphite 0.04 parts by weight and calcium stearate 0.07 parts by weight,
The mixture was sufficiently stirred and mixed with a Henschel mixer.

Thereafter, the mixture was melted and kneaded by an extruder having a cylinder temperature set to 230 ° C. to obtain PP-1 pellets.

(8) PP-2 The isotactic pentad fraction of the boiling heptane-insoluble portion is 0.979%, the ratio of the boiling heptane-insoluble portion to the whole polymer is 86%, the MFR is 17 g / 10 min, and the content of ethylene is Except that the base polymer was 100 parts by weight of a highly crystalline block polypropylene having an amount of 4.5 wt% and a melting point of 164 ° C.
A P-2 pellet was obtained.

(9) PH-1; MFR = 29, melting point 14
7 ° C. propylene butene random copolymer (butene content 5.0 wt%), tetrakis [methylene (3,5-di-t-butyl-4-hydroxyhydrocinnamate)] methane 0.04 parts by weight, tris ( 2,4-di-t
-Butylphenyl) phosphite 0.04 parts by weight and calcium stearate 0.07 parts by weight,
The mixture was sufficiently stirred and mixed with a Henschel mixer.

Thereafter, the mixture was melted and kneaded by an extruder having a cylinder temperature of 230 ° C. to obtain pellets of PH-1. The sphere volume equivalent diameter of the pellet was about 2 mm.

(10) PH-2; MFR =
4. PH-2 pellets were obtained by the same operation as PH-1, except that a propylene butene random copolymer having a melting point of 152 ° C. (butene content: 4.5 wt%) was used. The sphere volume equivalent diameter of the pellet was about 2 mm.

(11) MFR = 2 as PH-3 raw material
A pellet was obtained in the same manner as in PH-1, except that a propylene ethylene random copolymer having a melting point of 145 ° C. (ethylene content: 4.2%) was used. The pellet was crosslinked with gamma rays to obtain a pellet of PH-3. The gel fraction of the pellets was 12% by weight. The sphere volume equivalent diameter of the pellet was about 2 mm.

(12) MFR = 12 as PH-4 raw material
PH-4 pellets were obtained by the same operation as PH-1, except that a propylene butene random copolymer having a melting point of 146 ° C. (butene content: 5.2 wt%) was used. The sphere volume equivalent diameter of the pellet was about 2 mm.

(13) MFR = 2 as PH-5 raw material
Pellets of PH-5 were obtained by the same operation as in PH-1, except that a propylene butene random copolymer having a melting point of 153 ° C (butene content: 4.7 wt%) was used. The sphere volume equivalent diameter of the pellet was about 2 mm.

(14) MFR = 2 as PH-6 raw material
A pellet of PH-5 was obtained by the same operation as PH-1, except that a propylene ethylene random copolymer having a melting point of 135 ° C. (ethylene content: 8.6%) was used. The sphere volume equivalent diameter of the pellet was about 3 mm.

Example 1 Using PP-1, a resin temperature of 230 ° C. and a mold temperature of 40
A gas pressure injection molding was performed at a temperature of 80 ° C. and a gas pressure of 80 MPa to prepare a door outer plate 3 and a door inner plate 4 as outer shells as shown in FIG. The door outer plate 3 has a height a of 650 mm, a width b of 450 mm, a thickness c of 50 mm, and a plate thickness d of 4 mm. The mold size at the distance e of the side surface is 442 mm.

The door inner plate was formed by a gas assist injection molding method using an ethylene propylene block copolymer having an MFR of 17 g / 10 min.

As a raw material, PH-1 was used.
Pre-expanded beads were prepared by a method according to-197027. That is, in a pressure-resistant closed container having an internal volume of 10 L,
2000 g of raw material polypropylene resin, 800 g of butane as a volatile foaming agent, 10 g of tricalcium phosphate,
0.5 g of sodium dodecylbenzenesulfonate in distilled water 6
And heated to 140 ° C. while stirring. Next, while maintaining the pressure in the container at about 3 MPa, the release valve attached to the pressure-resistant closed container is opened, the contents are released under atmospheric pressure, and the contents are exposed to warm air at 50 ° C. for 48 hours, and the expansion ratio is about 30 Double pre-expanded particles were obtained.

The pre-expanded particles thus obtained are stored in a pressure-resistant container, kept in nitrogen at 130 ° C. for 30 minutes at 2 MPa, and then depressurized to atmospheric pressure to obtain pre-expanded beads having expanded ability. Was. This is immediately filled in a closed mold,
After heating with steam, the mixture was cooled to obtain a foam having an expansion ratio of 33 times. When the obtained foam was subjected to Soxhlet extraction with boiling para-xylene for 12 hours, no gel component remained.

The foam obtained above was assembled in the door shell formed earlier, the door inner plate was subjected to vibration welding, and further packing was attached to complete the door.

This door was attached to the opening of the main body of the small refrigerator by using the mounting bracket, and it was confirmed that the door was excellent in hermeticity, heat insulation, etc., free of cold air leakage, and sufficiently usable as a refrigerator door.

Next, the refrigerator door was removed from the refrigerator body, the packing and the inner plate were removed, and the refrigerator was pulverized with a pulverizer. The obtained crushed pieces were put into a hopper of a 150-ton injection molding machine to form test pieces for physical properties, and the tensile elongation at break and flexural modulus were measured, and the appearance was observed. The results are shown in Table 1.

Example 2 A foam obtained by using PH-2 as a foam raw material (expansion ratio 28 times) was used. When the obtained foam was subjected to Soxhlet extraction with boiling para-xylene for 12 hours, no gel component remained. Otherwise, the same operations as in Example 1 were performed, and the results are shown in Table 1.

Example 3 Example 1 was repeated except that PP-2 was used as a raw material for the door skin.
And the results are shown in Table 1.

Comparative Example 1 A foam obtained by using PH-3 as a foam raw material (expansion ratio 16 times) was used. When the obtained foam was subjected to Soxhlet extraction with boiling para-xylene for 12 hours, the gel content remained at 33% by weight. Otherwise, the same operations as in Example 1 were performed, and the results are shown in Table 1.

Example 4 A foam obtained by using PH-4 as a foam raw material (expansion ratio 23 times) was used. When the obtained foam was subjected to Soxhlet extraction with boiling para-xylene for 12 hours, no gel component remained. Otherwise, the same operations as in Example 1 were performed, and the results are shown in Table 1.

Example 5 A foam obtained by using PH-5 as a foam raw material (expansion ratio: 28) was used. When the obtained foam was subjected to Soxhlet extraction with boiling para-xylene for 12 hours, no gel component remained. Otherwise, the same operations as in Example 1 were performed, and the results are shown in Table 1.

Example 6 A foam (expansion ratio 22 times) obtained by using PH-6 as a raw material of the foam was used. When the obtained foam was subjected to Soxhlet extraction with boiling para-xylene for 12 hours, no gel component remained. Otherwise, the same operations as in Example 1 were performed, and the results are shown in Table 1.

Comparative Example 2 A door inner plate having a hole having a diameter of 8 mm was set on a door outer plate obtained in the same manner as in Example 1, and fixed with a jig to form an outer shell.
Next, the mixture of the polyol and the foaming agent and the isocyanate were mixed and stirred for about 5 seconds, immediately injected through a hole in the door inner plate, and foamed inside the door. The expansion ratio of the obtained rigid urethane foam was about 24 times.

Thereafter, the door inner plate and the rigid urethane foam were removed from the door outer plate, but urethane was slightly adhered and remained on the outer shell. The outer shell is pulverized by a pulverizer, and the obtained pulverized pieces are put into a hopper of a 150-ton injection molding machine to form a test piece for physical properties, measurement of tensile elongation at break and flexural modulus, and observation of appearance. did. The results are shown in Table 1.

[0087]

[Table 1]

[Brief description of the drawings]

FIG. 1 is a perspective view showing a typical shape of a heat-insulated molded article of the present invention.

FIG. 2 is a perspective view showing a typical shape of a heat-insulated molded body of the present invention.

FIG. 3 is a perspective view showing a typical shape of a refrigerator door using the heat-insulating molded body of the present invention.

[Explanation of Signs] 1 outer shell 2 foam 3 outer shell of refrigerator door 4 inner plate of refrigerator door 5 foam of refrigerator door 6 packing of refrigerator door

[Explanation of symbols]

Continued on the front page F-term (reference) 3H036 AA08 AB18 AB25 AC01 AE13 3L102 JA01 JA02 JA06 JA08 KA01 KE01 MA01 MB16 MB17 4F100 AK07A AK07B AK67 AL03 AT00A BA02 BA10A CA01 CA05 CA19 DB17A DJ01B EJ02 GB07 GB33BJ02J07 GB33 GB48BJ JA1

Claims (2)

[Claims] 1. A heat-insulated molded article characterized in that a substantially non-crosslinked polypropylene resin foam is filled in an outer shell made of a polypropylene resin. 2. The polypropylene resin constituting the outer shell and the polypropylene resin constituting the foam have an MFR ratio of 0.2 to 5 and a difference in melting point of 25 ° C. or less. Heat-insulated moldings.