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Composite foamed polypropylene resin molding and method of producing same

a polypropylene resin and composite foam technology, applied in the direction of thin material processing, transportation and packaging, layered products, etc., can solve the problems of pp molding being apt to shrink to a size smaller than, prone to and general unavoidable shrinkage of low density sections

Inactive Publication Date: 2007-02-01
JSP CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a method for producing a composite foamed polypropylene resin molding by filling expanded beads of a base resin in a mold and heating them to fuse-bond them together. The expanded beads show a high temperature endothermic peak in their DSC curve. The method can produce moldings with different characteristics, such as color, density, composition, and mechanical strengths. The moldings have a high degree of foam and are stable. The technical effects of the invention include improved foam stability, reduced shrinkage, and improved mechanical strength.

Problems solved by technology

The PP molding is also apt to shrink to a size smaller than the mold cavity, when the molding is excessively cooled after the fuse-bonding of expanded PP beads has been completed.
In this case, since a relatively low density section is more quickly cooled than a relatively high density section, the low density section is more likely to shrink, when the cooling of the molding is carried out evenly.
Thus, the shrinkage of the low density section is generally unavoidable in the case of production the dual density PP molding unless specifically controlled cooling conditions are adopted.

Method used

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  • Composite foamed polypropylene resin molding and method of producing same
  • Composite foamed polypropylene resin molding and method of producing same
  • Composite foamed polypropylene resin molding and method of producing same

Examples

Experimental program
Comparison scheme
Effect test

preparation examples 1-4 , 8 and 9

PREPARATION EXAMPLES 1-4, 8 And 9

Preparation of Expanded PP Beads:

[0176] 100 Parts of polypropylene homopolymer (base resin) having a melting point, MFR and a tensile strength indicated in Table 1 were blended with 0.05 part of zinc borate powder (cell controlling agent) and the blend was kneaded in an extruder and extruded into strands. The strands were immediately introduced in water at 25° C. for quenching. The cooled strands were taken out from the water and then cut into particles each having a length / diameter ratio of about 1.0 and a mean weight of 2 mg.

[0177] In a 400 liter autoclave, 100 kg of the above resin particles were charged together with 120 kg of ion-exchanged water at 25° C. (dispersing medium; weight ratio of the resin particles to the dispersing medium: 0.83), 0.002 kg of sodium dodecylbenzenesulfonate (surfactant), 0.4 kg of kaolin powder (dispersing agent), 0.013 kg of aluminum sulfate powder (dispersion enhancing agent), and 0.32 kg of bis(4-t-butyl-cyclohe...

preparation examples 5-7

Preparation of Expanded PP Beads:

[0178] Using polypropylene homopolymer (base resin) having a melting point, MFR and a tensile strength indicated in Table 1, resin particles were prepared in the same manner as that of the above Preparation Examples.

[0179] In a 400 liter autoclave, 100 kg of the thus obtained resin particles were charged together with 220 kg of ion-exchanged water (dispersing medium; weight ratio of the resin particles to the dispersing medium: 0.45), 0.005 kg of sodium dodecylbenzenesulfonate (surfactant), 0.3 kg of kaolin powder (dispersing agent), and 0.01 kg of aluminum sulfate powder (dispersion enhancing agent). Then, carbon dioxide (blowing agent) was fed to the autoclave under pressure until the inside pressure thereof was stabilized at 0.49 MPa(G). The dispersion in the autoclave was then stirred, heated to a temperature lower by 5° C. than the expansion temperature shown in Table 1 at an average heating rate of 4° C. / min. Thereafter, the temperature was ...

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Abstract

A composite foamed polypropylene resin molding including a plurality of sections which are fuse-bonded to each other, at least two of which differ from each other in color, apparent density, composition and / or mechanical strengths, each of which is formed from expanded polypropylene resin beads, and each of which shows a high temperature endothermic peak in a DSC curve thereof. At least one of the sections satisfies conditions (d) to (f) at the same time: (d) to be formed from specific expanded polypropylene resin beads of a base resin having a tensile modulus of at least 1,200 MPa, (e) to have an apparent density D2 of 10-500 g / L, and (f) to have such a high temperature endothermic peak with a calorific of E2 J / g, wherein D2 and E2 have the relationship 20−0.020×D2≦E2≦65−0.100×D2. The composite molding may be prepared by filling expanded polypropylene resin beads in each of a plurality of contiguous spaces defined in a mold cavity and heating the expanded beads to fuse-bond respective expanded beads together into a unitary body. At least one of the spaces is filled with the specific expanded polypropylene resin beads.

Description

TECHNICAL FIELD [0001] This invention relates to a composite foamed polypropylene resin molding and to a method of producing same. BACKGROUND ART [0002] A polypropylene resin is now increasingly utilized in various fields because of excellent mechanical strengths, heat resistance, chemical resistance, machinability, cost balance and recyclability thereof. Foamed moldings of a base resin including a polypropylene resin (hereinafter referred to simply as “PP moldings” or “polypropylene resin moldings”), which retain the above excellent properties and which have excellent additional characteristics such as cushioning property and heat insulating properties, are thus utilized for various applications as packaging materials, construction materials, heat insulation materials, etc. In particular, PP moldings obtained by heating expanded beads of a base resin including a polypropylene resin (hereinafter referred to as “expanded PP beads” or “expanded polypropylene resin beads”) in a mold ar...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B32B7/02B32B3/00B32B3/26B29C44/04B29C44/34B29C44/44
CPCB29C44/0469Y10T428/24992B29C44/445B29C44/3461Y10T428/249971Y10T428/249977Y10T428/249953Y10T428/249981B29C44/3426B29C44/04B29C44/44
Inventor HIRA, AKINOBUHASHIMOTO, KEIICHISASAKI, HIDEHIRO
Owner JSP CORP