JP2003128823A - Polypropylene resin molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin molding exhibiting a small degree of deformation such as a sink mark and warpage by suppressing deterioration in appearance (surface roughening) and by foaming. SOLUTION: A polypropylene resin comprising a composition (A) in 10-100 wt.% based on the polypropylene resin is foamed using a foaming agent to prepare the resin molding having a difference in dimensions along a vertical section of 4% or less and the surface roughness being suppressed. The polypropylene composition (A) comprises (a) 0.01-5.0 pts.wt. of an ethylene homopolymer having a specific intrinsic viscosity or an ethylene-olefin copolymer containing an ethylene polymerization unit in 50 wt.% or more and (b) 100 pts.wt. of a propylene homopolymer having a specific intrinsic viscosity or a propylene-olefin copolymer containing a propylene polymerization unit in 50 wt.% or more.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a resin molded product obtained by foaming a specific polypropylene resin with a foaming agent. More specifically, there is little warpage / deformation, vehicle parts,
The present invention relates to a resin molded product suitable for electric equipment parts, containers and the like.

[0002]

2. Description of the Related Art Polypropylene resin is widely used as a thermoplastic resin which is excellent in mechanical properties and chemical resistance and is inexpensive in moldings in various fields. However, a polypropylene resin molded product has a problem such as poor shape reproducibility due to deformation such as shrinkage and warpage due to crystallization shrinkage and the like. On the other hand, a method of adding a foaming agent to a polypropylene resin to obtain a resin molded body having a sink preventive measure has been partially put into practical use. However, in the case of resin moldings made by adding a foaming agent to polypropylene resin, the foaming gas may separate from the molten resin during molding, and the surface condition of the resulting moldings may deteriorate (rough skin). Although it is excellent in that respect, it has not been widely put into practical use.

[0003]

DISCLOSURE OF THE INVENTION The present inventors have diligently studied to improve the surface appearance of a resin molded product obtained by foaming a polypropylene resin with a foaming agent and at the same time obtain a resin molded product with less warpage. . As a result, it was found that a resin molded product obtained by foaming a specific polypropylene resin with a foaming agent improves the surface appearance and at the same time becomes a molded product with less warp, and based on this finding, the present invention was completed. did. As is clear from the above description, the object of the present invention is a resin molded product obtained by foaming a specific polypropylene resin with a foaming agent, and suppressing deterioration of the surface appearance of the resulting resin molded product (rough skin). The present invention provides a resin molded body that is less deformed by sinking, warping, etc. by foaming.

[0004]

Means for Solving the Problems The present invention comprises (1) a polypropylene composition containing the following polypropylene composition (A) in an amount of 10 to 100% by weight based on the polypropylene resin, using a foaming agent. A resin molded product, which is a foamed molded product having a dimensional difference of 4% or less in the vertical section direction of the molded product and suppressing surface roughening. Here, the polypropylene composition (A) has the following (a),
An olefin polymer composition comprising (b) and a blending ratio. (A) an ethylene homopolymer or an ethylene-olefin copolymer containing 50% by weight or more of ethylene polymer units, wherein the intrinsic viscosity [η] _E measured in tetralin at 135 ° C. is in the range of 15 to 100 dl / g. (B) 0.01 to 5.0 parts by weight of polyethylene (a), propylene homopolymer or propylene-olefin copolymer containing 50% by weight or more of propylene polymer units,
Polypropylene (b) 10 having an intrinsic viscosity [η] _P of 0.2 to 10 dl / g measured in tetralin at 135 ° C
0 parts by weight.

(2) The resin molded article according to the above item 1, wherein the polypropylene resin is a polypropylene resin containing 10 to 100% by weight of the following polypropylene composition (B) with respect to the polypropylene resin. Here, the polypropylene composition (B) is a composition comprising the following (a), (b), (c) and a blending ratio. (A) an ethylene homopolymer or an ethylene-olefin copolymer containing 50% by weight or more of ethylene polymer units, wherein the intrinsic viscosity [ηE] measured in tetralin at 135 ° C. is in the range of 15 to 100 dl / g. A polyethylene (a) of 0.01 to 5.0 parts by weight, (b) a propylene homopolymer or a propylene-olefin copolymer containing 50% by weight or more of propylene polymer units,
Polypropylene (b) 10 having an intrinsic viscosity [ηP] of 0.2 to 10 dl / g measured in tetralin at 135 ° C
0 parts by weight, (c) 0.01 to 60 parts by weight of an inorganic filler having an average particle size of 0.5 to 10 μm.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The resin molded product of the present invention means a molded product obtained by molding a polypropylene resin using a foaming agent. Examples of the foaming agent used include nitrogen, carbon dioxide, n-butane, freon, ammonium carbonate, sodium hydrogen carbonate, citric acid, azodicarbonamide (ADC
A), 2,2'-azoisobutyronitrile, azohexahydrobenzonitril, diazoaminobenzene, benzenesulfohydrazide, benzene-1,3-disulfohydrazide, diphenylsulfone-3,3-disulfohydrazide, diphenyl oxide -4,4-disulfohydrazide, N, N-dinitropentamethylenetetramine, N,
N-dimethyl terephthalate, terephthal azide, p-
Examples thereof include tert-butylbenzazide. You may use these foaming agents individually or in mixture of 2 or more types.

As a method for obtaining the resin molding of the present invention,
0.5-1 for 100 parts by weight of polypropylene resin
A method of mixing 0 parts by weight of a foaming agent with a polypropylene resin using a mixer such as a tumbler mixer, and then charging the resulting mixture into a molding machine to mold the polypropylene resin in a cylinder of the molding machine. After melting, a foaming agent (gas) having a compounding ratio of 0.5 to 10 parts by weight with respect to 100 parts by weight of the polypropylene resin is directly injected into the molten resin through a gas injection port provided in the cylinder, and molding is performed. Although any of the above methods may be used, the preferred manufacturing method is the injection molding method described below.

That is, using an injection molding machine equipped with a heating cylinder and a mold, an injection molding method (cavity) including a) injection step, b) primary cooling step, c) foaming step, and d) secondary cooling step. Expansion method foaming method), a) injection process,
An injection molding method (short shot method) or the like including b) a foaming step and c) a cooling step. As the shape of the resin molding,
It is a flat, disk-shaped, or box-shaped molded body, and those having rib portions or the like on them can also be exemplified.

The dimensional difference (%) in the vertical section direction of the resin molding is the maximum value (X) and the minimum value of the vertical section dimensions of the molding.
(Y) is measured and calculated using the following equation (1). (See Fig. 1) Dimensional difference (%) in the direction of vertical section of molded product = (X-Y) / X x 100 (1)

The roughness of the surface of the molded product is visually checked for the traces of gas out of the surface of the molded product, and the extent of the trace is sensory evaluated according to the following criteria. ◯: Less rough skin, Δ: A little rough skin, ×: Remarkably rough skin, and rough skin being suppressed is evaluated as “◯: Little rough skin”.

The polypropylene composition (A) used for the resin molding of the present invention will be described. The polypropylene composition (A) used in the present invention is a polymer composition having the following properties, that is, a polymer composition comprising the following (a) and (b) and their compounding ratios. (A) an ethylene homopolymer or an ethylene-olefin copolymer containing 50% by weight or more of ethylene polymer units, wherein the intrinsic viscosity [η] _E measured in tetralin at 135 ° C. is in the range of 15 to 100 dl / g. From 0.01 to 5.0 parts by weight of polyethylene (a), (b) a propylene homopolymer or a propylene-olefin copolymer containing 50% by weight or more of propylene polymer units,
Polypropylene (b) 10 having an intrinsic viscosity [η] _P of 0.2 to 10 dl / g measured in tetralin at 135 ° C
0 parts by weight.

The method for obtaining such a polypropylene composition (A) is not particularly limited, but for example, the method disclosed in International Publication WO97 / 14725, that is, a combination of a supported titanium-containing solid catalyst component and an organoaluminum compound is combined. The olefin polymerization catalyst system is used to polymerize a predetermined amount of high-molecular-weight polyethylene having an intrinsic viscosity [η] _{E in} the range of 15 to 100 dl / g, and then an intrinsic viscosity [η] _P of 0.2 to It can be prepared by a two-stage polymerization method in which a predetermined amount of polypropylene of 10 dl / g is polymerized. The intrinsic viscosity is tetralin as a solvent,
Automatic viscosity measuring device (AVS2 type,
It is a value measured by Mitsui Toatsu Chemicals, Inc.).

When the intrinsic viscosity [η] _{E of} polyethylene (a) is less than 15 dl / g, the effect of suppressing rough skin of a resin molded product molded from the obtained polypropylene composition (A) may not be obtained. There is no particular upper limit to the intrinsic viscosity [η] _E , but the upper limit is 100 dl / g from the viewpoint of poor dispersion of polyethylene (a) in polypropylene (b) and production efficiency. It will be about.

The polypropylene composition (B) has an average particle size of 0.5 to 1 in addition to the polypropylene composition (A).
It is a mixture of 0 μ of inorganic filler in a mixing ratio of 0.01 to 60 parts by weight. As the inorganic filler, fillers such as glass fiber, talc, mica may be used alone or in combination of two or more kinds. If the average particle size is less than 0.5 μ, it is difficult to finely disperse the inorganic filler, and if it exceeds 10 μ, the impact strength of the obtained resin molded product may be reduced. Further, when the blending ratio of the inorganic filler is less than 0.01 part by weight, the polypropylene resin (A) (when the inorganic filler is not included) and the resulting molded article have rough skin and a dimensional difference (%) in the vertical section direction. If the amount is more than 60 parts by weight, the moldability may decrease.

The polypropylene compositions (A) and (B) thus obtained are used as they are, or as a mixture with other resins, as a polypropylene resin for producing the molded article of the present invention. . The amount of the polypropylene composition (A) or (B) contained in the polypropylene resin varies depending on the shape of the obtained molded product, but is 10% by weight or more, preferably 20% by weight or more, based on the polypropylene resin. More preferably 50% by weight
That is all. The upper limit of the content of the polypropylene composition (A) in the polypropylene resin is 100% by weight.

Here, other resins that can be used by mixing with the polypropylene composition (A) or (B) include ordinary polypropylene such as polypropylene homopolymer and propylene-ethylene copolymer, maleic acid-modified polypropylene, High density polyethylene, medium density polyethylene, low density polyethylene, linear low density polyethylene, linear ultra low density polyethylene, ethylene-vinyl acetate copolymer and other ethylene resins, syndiotactic polypropylene resins, butene resins, Cyclic olefin resin, petroleum resin, styrene resin, acrylic resin, fluororesin, ethylene-propylene copolymer rubber, polyolefin rubber such as ethylene-butene copolymer rubber, polyamide resin, polyester resin and the like, These do not impair physical properties and moldability. To the extent, alone, or,
Two or more kinds can be mixed and used.

The polypropylene composition (A) and (B)
Include antioxidants, UV absorbers, lubricants, antistatic agents,
Additives which are usually used in polypropylene such as colorants, flame retardants and nucleating agents can be added in appropriate amounts.

[0018]

EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples.

(1) Measurement method of each numerical value and notation of evaluation result: (i) Intrinsic viscosity: Automatic viscosity measuring device (AVS2 type, Mitsui Toatsu Kagaku Co., Ltd.) using tetralin as a solvent under a temperature condition of 135 ° C.
(Manufactured by KK) (unit: dl / g). (Ii) MFR: JIS K7210 Table 1 Condition 14
(230 ° C, 21.18N). (Iii) As for the rough surface of the molded product, the traces of gas out of the surface of the box-shaped molded product were visually confirmed as described above, and the degree of the trace was sensory-evaluated according to the following criteria. ○: Less rough skin, △: Some rough skin, ×: Significant rough skin (iv) Dimensional difference in vertical section direction of molded product (%): Measure vertical section size from corner of opening of box-shaped molded product Was calculated from the above equation (1).

(I) Polypropylene composition (A): Intrinsic viscosity [η] composed of the following (a) and (b) prepared by the two-stage polymerization method disclosed in International Publication WO 97/14725 is 2.0 dl. / G polymer composition, (a) 135
Intrinsic viscosity [ηE] measured in tetralin at ℃ is 31d
0.25 part by weight of a high molecular weight ethylene homopolymer of 1 / g, (b) 100 parts by weight of a propylene homopolymer having an intrinsic viscosity [ηP] of 2.0 dl / g measured in tetralin at 135 ° C.

Polypropylene: propylene homopolymer, MFR = 4 Talc: Fuji Talc LMS300, average particle size, 1.3 μm

Example 1 To 100 parts by weight of the above-mentioned polypropylene composition (A),
1,1,3-tris (2-methyl-4-hydroxy-5)
0.1 part by weight of -t-butylphenyl) butane, 0.2 part by weight of calcium stearate and 1.5 parts by weight of azodicarbonamide (ADCA) as a foaming agent are added at a compounding ratio and mixed by a tumbler mixer for molding. Material 10k
g was obtained. Using an injection molding machine having a heating cylinder with a screw diameter of 50 mm and a mold clamping control mechanism and a maximum mold clamping force of 300 tons, the temperature of each heating zone of the heating cylinder is sequentially changed from the front end to the rear end using this molding material. 230 ° C,
The temperature is set to 230 ° C, 230 ° C, 210 ° C, and 180 ° C, the back pressure is 100 kg / cm ² , and the mold cooling water temperature is 4
At 0 ° C, 230 mm x 115 mm, depth 115 mm,
A box-shaped cavity having a wall thickness of 2 mm was injection-filled with the molding material that had been heated and melted. The injection filling amount was adjusted to the minimum amount at which the box-shaped molding was completely filled. Then, the mold was cooled for 40 seconds to obtain a box-shaped resin molded body. The rough surface of the resin molded product and the dimensional difference (%) in the vertical section direction were measured. The results are shown in Table 1.

Examples 2 to 4 Polypropylene composition (A) similar to that used in Example 1
100 parts by weight of 1,1,3-tris (2-methyl-4)
-Hydroxy-5-t-butylphenyl) butane 0.1
By weight, 0.2 parts by weight of calcium stearate, talc as an inorganic filler, and ADCA as a foaming agent were mixed in the proportions shown in Table 1 below to obtain 10 kg of each molding material. Injection molding was carried out according to Example 1 using the molding material to produce a resin molded body. The surface roughness and the dimensional difference (%) in the vertical section direction of the obtained resin molded product were measured. The results are shown in Table 1.

Examples 5 and 6 The same polypropylene composition (A) as used in Example 1, polypropylene, talc and ADCA were blended in the proportions shown in Table 1 below to prepare 1,1,3-tris. 0.1 parts by weight of (2-methyl-4-hydroxy-5-t-butylphenyl) butane and 0.2 parts by weight of calcium stearate were mixed to obtain 10 kg of each molding material. Using the obtained molding material, injection molding was carried out according to Example 1 to obtain a resin molded body. The surface roughness of the obtained resin molded product and the dimensional difference (%) in the vertical section direction were measured, and the results are shown in Table 1.

Comparative Examples 1 and 2 Polypropylene composition (A), polypropylene and talc were blended in the proportions shown in Table 1 below, and 1,
1,3-tris (2-methyl-4-hydroxy-5-t
-Butylphenyl) butane (0.1 parts by weight) and calcium stearate (0.2 parts by weight) were mixed to obtain 10 molding materials each.
I got kg. Injection molding was carried out according to Example 1 using the obtained molding material to obtain a resin molded body. Roughness of the obtained resin molding and dimensional difference in the direction of vertical section (%)
Was measured and the results are shown in Table 2.

[0026]

[Table 1]

[0027]

[Table 2]

[0028]

The resin molded product of the present invention is a resin molded product having an improved surface appearance (roughness) and at the same time less warp and deformation.

[Brief description of drawings]

FIG. 1 is a diagram showing a portion where a vertical section dimension is measured from a corner of a resin molded body and an opening thereof.

[Explanation of symbols]

L: represents a vertical section size.

Continued front page    F term (reference) 4F074 AA17 AA17A AA24 AA24A                       AA24B AA24C AC34 AC36                       AE04 BA03 BA04 BA13 BA14                       BA16 BA18 BA20 BA32 BA33                       BA37 BA53 CA26 CC03X                       CC04X DA23 DA34 DA35                       DA47                 4J002 BB022 BB032 BB052 BB111                       BB121 BB141 BP021 DJ046                       DJ056 DL006 FA046 GG01                       GN00 GQ00

Claims (2)

[Claims] 1. A molded article obtained by foaming the following polypropylene composition (A) with a blowing agent containing a polypropylene resin containing 10 to 100% by weight of the polypropylene resin, and a vertical section of the molded article. A resin molded product having a dimensional difference in direction of 4% or less and suppressing surface roughening. Here, the polypropylene composition (A) has the following (a),
An olefin polymer composition comprising (b) and a blending ratio. (A) an ethylene homopolymer or an ethylene-olefin copolymer containing 50% by weight or more of ethylene polymer units, wherein the intrinsic viscosity [ηE] measured in tetralin at 135 ° C. is in the range of 15 to 100 dl / g. A propylene-olefin copolymer containing 0.01 to 5.0 parts by weight of polyethylene, (b) a propylene homopolymer or 50% by weight or more of propylene polymer units,
The intrinsic viscosity [ηP] measured in tetralin at ℃ is 0.2
100 parts by weight of polypropylene, which is -10 dl / g. 2. A polypropylene resin comprises the following polypropylene composition (B):
The resin molded product according to claim 1, which is a polypropylene resin containing 0 to 100% by weight, wherein the polypropylene composition (B) is a composition comprising the following (a), (b), (c) and a blending ratio. It is a thing. (A) an ethylene homopolymer or an ethylene-olefin copolymer containing 50% by weight or more of ethylene polymer units, wherein the intrinsic viscosity [ηE] measured in tetralin at 135 ° C. is in the range of 15 to 100 dl / g. A polyethylene (a) of 0.01 to 5.0 parts by weight, (b) a propylene homopolymer or a propylene-olefin copolymer containing 50% by weight or more of propylene polymer units,
Polypropylene (b) 10 having an intrinsic viscosity [ηP] of 0.2 to 10 dl / g measured in tetralin at 135 ° C
0 parts by weight, (c) 0.01 to 60 parts by weight of an inorganic filler having an average particle size of 0.5 to 10 μm.