JP2006257258A - Molded article for automobiles using propylene resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a molded article for automobiles excellent in stability for molding cycles during injection molding and durable properties owing to enabling a prevention of bad dispersion of a nucleating agent. <P>SOLUTION: A composition (1) is obtained by adding a nucleating agent to a propylene resin (A) and kneading; a composition (2) is obtained by adding a propylene resin (B) to the composition (1) and kneading; a composition (3) is obtained by adding a rubber to the composition (2) and kneading; and the molded article is obtained by molding the composition (3). Alternatively, a composition (1) is obtained by adding a nucleating agent to a propylene resin (A) and kneading; a composition (4) is obtained by adding a propylene resin (B) and a rubber to the composition (1) and kneading; and the molded article is obtained by molding the composition (4). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a molded article obtained by molding a composition produced by a specific method. More specifically, the present invention relates to a molded article for automobiles obtained by molding a composition having excellent molding cycle stability and durability during injection molding.

  The durable physical property indicates a physical property difference before and after aging under a high-temperature heating condition or a high-humidity condition, and is required to have little change.

  It is known that a thermoplastic elastomer composition composed of polypropylene and rubber can be improved in various physical properties by adding a nucleating agent. The improved physical properties include various properties such as fluidity, molding cycle, surface appearance, rigidity, transparency, impact strength, and the obtained effect varies depending on the type and amount of the nucleating agent to be applied.

  For example, Patent Document 1 discloses a technique for improving fluidity and surface appearance by using a crosslinked thermoplastic elastomer composition and a nucleating agent. Patent Document 2 discloses a technology that achieves both rigidity and low-temperature impact by using a thermoplastic elastomer composition and a specific nucleating agent.

  Although these technologies can be used to improve the intended physical properties, the nucleating agent is basically incompatible with the olefin resin, so the properties, kneading conditions, and addition of the nucleating agent Depending on the method, a sufficient improvement effect may not be obtained.

  The nucleating agent is a component that assists in the crystallization of the resin. In the composition of the present invention, it is important that the nucleating agent is uniformly dispersed in the propylene-based resin that becomes the sea phase. For example, even if a nucleating agent is present in the rubber that is the island phase of the composition, the change in physical properties is small due to low crystallinity, and the physical property improving effect of the molded article is low. In addition, when the nucleating agent is contained in the rubber, the effect of assisting the crystallization of the propylene-based resin is reduced, and the intended effect may not be obtained. Specifically, non-uniform crystallization of the propylene-based resin may increase the variation in mechanical properties of the molded body or may impair the stability of the molding cycle.

JP-A-8-100090 JP 2002-146105 A

  The problem to be solved by the present invention is that it is possible to prevent the dispersion of the nucleating agent by producing by a specific method, the molding cycle stability at the time of injection molding is excellent, and the molding having excellent durability properties Provide the body.

  That is, the present invention provides a composition (1) by adding a nucleating agent to a propylene resin and kneading, and adding a propylene resin to the composition (1) and kneading the composition (1). The composition (2) is obtained by adding rubber to the composition (2) and kneaded to obtain the composition (3), and the molded article obtained by molding the composition (3).

  According to the present invention, it is possible to suppress the dispersion of the nucleating agent, and to provide a molded article for an automobile that is excellent in the stability of the molding cycle during injection molding and the excellent physical properties.

  The composition (1) of the present invention can be obtained by adding a nucleating agent to the propylene resin (A) and kneading.

  The propylene-based resin (A) is a polymer containing a monomer unit derived from propylene and a monomer unit derived from a chain olefin having 2 to 20 carbon atoms (excluding propylene). is there. Examples of the chain olefin having 2 to 20 carbon atoms (excluding propylene) include, for example, ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1- Linear olefins such as decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, 3- Examples include branched olefins such as methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 2-ethyl-1-hexene, and 2,2,4-trimethyl-1-pentene. One or more of these are used.

  Specific examples of the propylene resin (A) include a propylene-ethylene copolymer, a propylene-1-butene copolymer, a propylene-1-hexene copolymer, a propylene-ethylene-1-butene copolymer, Examples thereof include a propylene-ethylene-1-butene copolymer. These may be random copolymers or block copolymers, but are preferably random copolymers.

  The content of the monomer unit derived from propylene in the propylene-based resin (A) is 70 to 99.8% by weight, preferably 80 to 99% by weight, more preferably 85 to 97% by weight. is there. However, the content of all monomer units of the propylene-based resin is 100% by weight. If the content is too small, the low temperature impact strength of the molded product may be insufficient, and if the content is too high, the rigidity and heat resistance of the molded product may be decreased. The content is measured with an infrared absorption spectrum measuring apparatus.

  The melt flow rate (MFR) of the propylene-based resin (A) is 1 to 150 g / 10 minutes, preferably 10 to 100 g / 10 minutes.

  If the MFR is too low, when added to the composition (2) or the composition (4) and melt-kneaded, poor dispersion may occur and the intended effect may not be obtained. On the other hand, if the MFR is too high, the mechanical properties of the molded product may deteriorate.

  The MFR is measured in accordance with JIS K7210 under conditions of a load of 21.2 N and a temperature of 230 ° C.

  The nucleating agent of the composition (1) refers to a substance having an effect of growing a crystal as a crystal nucleus when added to a crystalline resin, and includes various substances. Examples of the nucleating agent include dibenzylidene sorbitol compounds, metal salts of carboxylic acids, phosphate metal salts, and the like, among which sorbitol compounds are preferable.

  Examples of the sorbitol compound include 1,3,2,4-dibenzylidene sorbitol, 1,3-benzylidene-2,4-p-methylbenzylidene sorbitol, 1,3-benzylidene-2,4-p-ethyl. Benzylidene sorbitol, 1,3-p-methylbenzylidene-2,4-benzylidene sorbitol, 1,3-p-ethylbenzylidene-2,4-benzylidene sorbitol, 1,3-p-methylbenzylidene-2,4-p- Ethylbenzylidenesorbitol, 1,3-p-ethylbenzylidene-2,4-p-methylbenzylidenesorbitol, 1,3,2,4-di (p-methylbenzylidene) sorbitol, 1,3,2,4-di ( p-ethylbenzylidene) sorbitol, 1,3,4,4-di (3,4-dimethylbenzylidene) Rubitol, 1,3,2,4-di (pn-propylbenzylidene) sorbitol, 1,3,2,4-di (pi-propylbenzylidene) sorbitol, 1,3,2,4-di ( pn-butylbenzylidene) sorbitol, 1,3,2,4-di (ps-butylbenzylidene) sorbitol, 1,3,2,4-di (pt-butylbenzylidene) sorbitol, 1,3 , 2,4-di (p-methoxybenzylidene) sorbitol, 1,3,2,4-di (p-ethoxybenzylidene) sorbitol, 1,3-benzylidene-2,4-p-chlorobenzylidenesorbitol, 1,3 -P-chlorobenzylidene-2,4-benzylidene sorbitol, 1,3-p-chlorobenzylidene-2,4-p-methylbenzylidene sorbitol, 1,3-p Chlorbenzylidene-2,4-p-ethylbenzylidene sorbitol, 1,3-p-methylbenzylidene-2,4-p-chlorobenzylidene sorbitol, 1,3-p-ethylbenzylidene-2,4-p-chlorobenzylidene sorbitol , And 1,3,2,4-di (p-chlorobenzylidene) sorbitol.

  Among these, 1,3,2,4-di (p-ethylbenzylidene) sorbitol and 1,3,2,4-di (3,4-dimethylbenzylidene) sorbitol are preferable, and 1,3,2,4 -Di (p-ethylbenzylidene) sorbitol is particularly preferred. These sorbitol compounds may be used alone or in combination.

  In the composition (1) of the present invention, when the total amount of the propylene-based resin (A) and the nucleating agent in the composition (1) is 100% by weight, the concentration of the nucleating agent is 1 to 50% by weight. It is manufactured by melt-kneading a nucleating agent formed of a propylene resin (A) and a sorbitol compound alone or in combination.

  If the concentration of the nucleating agent in the composition (1) is low, it is necessary to increase the amount added to the composition (2) or the composition (4), which is not preferable in terms of the productivity and economical efficiency of the composition. Moreover, when the density | concentration of a nucleating agent is high, it is unpreferable from a viewpoint of the dispersion | distribution defect of a nucleating agent, or an odor.

  In the composition (1) of the present invention, the propylene resin (A) and the nucleating agent are stirred and mixed by a known method such as a ribbon blender, tumbler mixer, Henschel mixer, super mixer, etc., and then the mixture is banbury mixer, extruded Using a machine or the like, the resin is melt kneaded at a resin temperature of 150 to 300 ° C, preferably 180 to 250 ° C. Of these, a twin screw extruder is preferably used from the viewpoint of dispersion of the nucleating agent.

  The composition (2) of the present invention is obtained by adding the propylene-based resin (B) to the composition (1) and kneading.

  The propylene-based resin is a polymer containing propylene and a chain olefin having 2 to 20 carbon atoms (excluding propylene). Examples of the chain olefin having 2 to 20 carbon atoms (excluding propylene) include, for example, ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1- Linear olefins such as decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicocene; Examples include branched olefins such as methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 2-ethyl-1-hexene, and 2,2,4-trimethyl-1-pentene. One or more of these are used.

  Specific examples of the propylene resin (B) include a propylene-ethylene copolymer, a propylene-1-butene copolymer, a propylene-1-hexene copolymer, and a propylene-ethylene-1-butene copolymer. Can give. These may be random copolymers or block copolymers.

  The propylene-based resin (B) includes a crystalline propylene homopolymer portion or a crystalline propylene-α-olefin random copolymer portion, which is the first segment polymerized in the first step, and a second segment polymerized in the second step. It is preferred to use a crystalline propylene-α-olefin block copolymer having a propylene-α-olefin random copolymer portion which is

When the propylene-based resin (B) is a propylene-α-olefin block copolymer, it is a polymer having a propylene homopolymer portion and a propylene-α-olefin random copolymer portion, and the following requirements (b1), (b2) and A polymer satisfying (b3) is preferred.
(B1) The content of the 20 ° C. xylene soluble part is 2.0% by weight or less (b2) The content of the boiling heptane soluble part is 5.0% by weight or less (b3) Propylene homopolymer part The isotactic pentad fraction of the insoluble part of boiling heptane is 0.970 or more

  The content of the 20 ° C. xylene-soluble part is measured by the following method. That is, 5 g of the propylene-based resin of component (a) is completely dissolved in 500 ml of boiling xylene, then left at 20 ° C. for 4 hours, and then filtered to separate the 20 ° C. xylene insoluble part. The filtrate is concentrated and dried to evaporate xylene and further dried at 60 ° C. under reduced pressure to obtain a polymer soluble in xylene at 20 ° C. The value obtained by dividing the dry weight by the charged sample weight is expressed as a percentage, which is the content of the 20 ° C. xylene soluble part.

  The content of the boiling heptane-soluble part is measured by the following method. That is, the 20 ° C. xylene insoluble part obtained by the measurement of the 20 ° C. xylene soluble part is dried and subjected to Soxhlet extraction with boiling n-heptane for 8 hours. This extraction residue is called a boiling heptane-insoluble part, and the value obtained by dividing the dry weight of the boiling heptane-insoluble part by subtracting the value obtained by subtracting the sample weight (5 g) from the sample weight is expressed as a percentage. Part content.

  The isotactic pentad fraction of the boiling heptane insoluble part is measured by using the boiling heptane insoluble part obtained by measuring the content of the boiling heptane soluble part.

The isotactic pentad fraction is an isotactic chain of pentad units in a crystalline polypropylene molecular chain measured using ¹³ C-NMR, in other words, 5 propylene monomer units in succession. The fraction of propylene monomer units at the center of the meso-bonded chain; The method published in Macromolecules, 6, 925 (1973) by Zambelli et al. Is performed by assignment of NMR absorption peaks based on Macromolecules, 8, 687 (1975). Specifically, the isotactic pentad fraction is measured as the area fraction of the mmmm peak in the total absorption peak in the methyl carbon region of the ¹³ C-NMR spectrum. By this method, NPL reference material CRM No. of UK NATIONAL PHYSICAL LABORATORY was used. When the isotactic pentad fraction of M19-14 Polypropylene PP / MWD / 2 was measured, it was 0.944.

  The block copolymer can be produced by a slurry polymerization method and a gas phase polymerization method. In particular, when used for applications requiring high impact resistance, it is necessary to increase the amount of the second segment, and it is preferably produced by a gas phase polymerization method.

  The content of monomer units derived from propylene in the propylene-based resin (B) is 60 to 99% by weight, preferably 70 to 98% by weight, and more preferably 80 to 97% by weight. However, the content of all monomer units of the propylene-based resin is 100% by weight. If the content is too low, the low-temperature impact strength of the resin composition may be insufficient, and if the content is too high, the rigidity and heat resistance of the resin composition may be reduced. The content is measured with an infrared absorption spectrum measuring apparatus.

  The melt flow rate (MFR) of the propylene resin (B) is 0.3 to 300 g / 10 minutes, preferably 0.5 to 100 g / 10 minutes, and more preferably 1 to 80 g / 10 minutes. . If the MFR is too small, the fluidity of the composition (3) may be insufficient, and if the MFR is too large, the impact strength of the molded article of the present invention may be reduced. The MFR is measured in accordance with JIS K7210 under conditions of a load of 21.2 N and a temperature of 230 ° C.

  The heat of fusion of the propylene-based resin (B) is 50 mJ / mg or more, preferably 55 mJ / mg or more, more preferably 60 mJ / mg or more. If the heat of fusion is too low, the polymer may cause mutual adhesion. Further, if the heat of fusion is too high, the low-temperature impact strength may be lowered. Therefore, it is preferably 150 mJ / mg or less, more preferably 120 mJ / mg or less.

  The heat of fusion is measured by a differential scanning calorimetry (DSC) method according to JIS K7122.

  As a manufacturing method of propylene-type resin (B), the well-known polymerization method using the well-known olefin polymerization catalyst is used. For example, a slurry polymerization method, a solution polymerization method, a bulk polymerization method, a gas phase polymerization method and the like using a complex catalyst such as a Ziegler-Natta catalyst, a metallocene complex, or a nonmetallocene complex can be used. It is also possible to use commercially available products.

  In the composition (2) of the present invention, the composition (1) and the propylene-based resin (B) are stirred and mixed by a known method such as a ribbon blender, tumbler mixer, Henschel mixer, super mixer, etc., and then the mixture is extruded. It is melt kneaded at 150 to 300 ° C., preferably 180 to 250 ° C. using a machine.

  Furthermore, from the viewpoint of enhancing the dispersibility of the nucleating agent, it is preferable to apply an extruder provided with a filter having an opening interval of 50 mesh or less, and among them, a sintered metal filter having an opening interval of 50 mesh or less is preferable. Application of the installed extruder is particularly preferred. When a filter having a mesh interval of less than 1000 mesh is used, the pressure difference before and after the filter becomes excessive, which may cause deterioration in productivity and deterioration of the composition.

  The composition (3) of the present invention is obtained by stirring and mixing the composition (2) and rubber by a known method such as a ribbon blender, tumbler mixer, Henschel mixer, super mixer, etc., and then mixing the mixture with various extruders and Banbury kneaders. It is obtained by melt-kneading at 150 to 300 ° C, preferably 180 to 250 ° C.

  In the composition (4) of the present invention, the composition (1), the propylene-based resin (B), and rubber are stirred and mixed by a known method, and various extruders and Banbury kneaders are used, and 150 to 300 ° C., preferably It is obtained by melt-kneading at 180 to 250 ° C.

  When producing the composition (3) or the composition (4) of the present invention, an extruder provided with a filter having an opening interval of 1000 mesh product or more and 50 mesh product or less from the viewpoint of enhancing the dispersibility of the nucleating agent. In particular, application of an extruder provided with a sintered metal filter having an opening interval of 1000 mesh product or more and 50 mesh product or less is particularly preferred.

  When a filter having a mesh interval of less than 1000 mesh is used, the pressure difference before and after the filter becomes excessive, which may cause deterioration in productivity and deterioration of the composition. If a filter having a mesh interval exceeding 50 mesh is used, the nucleating agent may not be sufficiently dispersed.

  The rubber used in the present invention is a polymer containing ethylene and a chain olefin having 3 to 20 carbon atoms and / or a non-conjugated diene.

  The rubber used in the present invention has a Mooney viscosity ML 100 ° C. (1 + 4) measured at a temperature of 100 ° C. of 30 to 150, preferably 40 to 140, more preferably 60 to 120. If the Mooney viscosity ML100 ° C. (1 + 4) is too small, the low-temperature impact strength may be insufficient, and if it is too large, the fluidity of the resin composition may be insufficient, resulting in poor molding. The Mooney viscosity ML100 ° C. (1 + 4) is measured according to ASTM D-927-57T.

  Examples of the chain olefin having 3 to 20 carbon atoms constituting the rubber used in the present invention include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, Linear olefins such as 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, etc. Branched olefins such as 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 2-ethyl-1-hexene and 2,2,4-trimethyl-1-pentene One or more of these are used.

  The content of the chain olefin having 3 to 20 carbon atoms constituting the rubber used in the present invention is 5 to 55% by weight, preferably 20 to 55% by weight, more preferably 35 to 55% by weight. However, the content of all monomer units in the rubber is 100% by weight. If the content is too small, the low temperature impact strength of the molded product may be insufficient, and if the content is too large, it may be easily compatible with the propylene resin, and the effect as an impact modifier may not be obtained. .

  The content of monomer units derived from non-conjugated dienes constituting the rubber used in the present invention is 0.1 to 30% by weight, preferably 0.3 to 15% by weight, more preferably 0.5 to 5%. % By weight. However, the content of all monomer units constituting the component (c) is 100% by weight. If the content is too small, fluidity at the time of injection molding may be insufficient, and if the content is too large, various durability properties of the molded product may be deteriorated.

  Content of the monomer which comprises the rubber | gum used for this invention is measured with an infrared absorption spectrum measuring apparatus.

  Examples of the non-conjugated diene constituting the rubber used in the present invention include dicyclopentadiene, 1,4-hexadiene, cyclooctadiene, methylene norbornene, and ethylidene norbornene. Of these, dicyclopentadiene and ethylidene norbornene are preferable.

  The content of monomer units derived from non-conjugated dienes constituting the rubber used in the present invention is 0.1 to 30% by weight, preferably 0.3 to 15% by weight, more preferably 0.5 to 5%. % By weight. However, the content of all monomer units in the rubber is 100% by weight. If the content is too small, the fluidity at the time of injection molding may be insufficient, and if the content is too large, various durability properties of the molded product may be deteriorated.

  As a method for producing the rubber used in the present invention, a known polymerization method using a known olefin polymerization catalyst is used.

  For example, it is produced by a slurry polymerization method, a solution polymerization method, a bulk polymerization method, a gas phase polymerization method or the like using a Ziegler-Natta catalyst, a complex catalyst such as a metallocene complex or a nonmetallocene complex. It is also possible to use commercially available products.

  Examples of the rubber used in the present invention include ethylene-propylene copolymer, ethylene-1-butene copolymer rubber, ethylene-1-hexene copolymer rubber, ethylene-1-octene copolymer, ethylene-propylene-1- In addition to copolymer rubbers of ethylene and linear olefins of 3 to 20 such as butene copolymer rubber and ethylene-1-butene-1-hexene copolymer rubber, ethylene-propylene-dicyclopentadiene copolymer Polymers, ethylene-propylene-ethylidene norbornene copolymer rubbers, ethylene-propylene-methylene norbornene copolymer rubbers and the like, monomers derived from ethylene, linear olefins of 3 to 20 primes, and non-conjugated dienes And a copolymer rubber.

  The glass transition temperature (Tg) of the rubber used in the present invention is −70 ° C. or higher, preferably −60 ° C. or higher, more preferably −50 ° C. or higher.

  When the Tg is too low, the polymers are likely to adhere to each other. In addition, the Tg is preferably −20 ° C. or less, more preferably −30 ° C. or less, from the viewpoint of production stability of the resin composition. The Tg is measured according to JIS K7121.

  The composition (3) or the composition (4) of the present invention includes a fatty acid having 5 or more carbon atoms, a metal salt of a fatty acid having 5 or more carbon atoms, or a carbon salt having 5 or more carbon atoms, from the viewpoint of enhancing releasability. It is preferable to include a release-imparting agent such as at least one compound selected from the group consisting of fatty acid amides and esters of fatty acids having 5 or more carbon atoms.

  Examples of the fatty acid having 5 or more carbon atoms used as a release-imparting agent include lauric acid, palmitic acid, stearic acid, 12-hydroxystearic acid, behenic acid, oleic acid, erucic acid, linoleic acid, ricinoleic acid, ethylenebisstearin Examples thereof include acid, ethylene bisoleic acid, hexamethylene bisoleic acid and the like.

  Examples of the metal salt of a fatty acid having 5 or more carbon atoms used as a release-imparting agent include salts of the above fatty acid and metals such as Li, Na, Mg, Al, K, Ca, Zn, Ba, and Pb. Specifically, lithium stearate, sodium stearate, calcium stearate, zinc stearate and the like can be exemplified.

  Examples of amides of fatty acids having 5 or more carbon atoms used as release-imparting agents include lauric acid amide, palmitic acid amide, stearic acid amide, oleic acid amide, erucic acid amide, methylene bis stearic acid amide, ethylene bis stearic acid amide And ethylene bisoleic acid amide, stearyl diethanolamide, and hexamethylene bisoleic acid amide. Of these, erucic acid amide is preferred.

  Examples of esters of fatty acids having 5 or more carbon atoms used as release-imparting agents include aliphatic alcohols (such as myristyl alcohol, palmityl alcohol, stearyl alcohol, behenyl alcohol, 12-hydroxystearyl alcohol), aromatic alcohols (benzyl alcohol, β-phenylethyl alcohol, phthalyl alcohol, etc.), polyhydric alcohols (glycerin, diglycerin, polyglycerin, sorbitan, sorbitol, propylene glycol, polypropylene glycol, polyethylene glycol, pentaerythritol, trimethylolpropane, etc.) Specifically, esters with the above fatty acids are glycerol monooleate, glyceroldiolate, polyethylene glycol monostearate, It can be exemplified acid distearate.

  The mold release imparting agent is preferably 0.01 to 5 parts by weight, more preferably 0.05 to 2 parts by weight, based on 100 parts by weight of the composition (3) or the composition (4). If the release imparting agent is too small, the effect of improving mold release at the time of molding can not be obtained, and if it is too much, mold contamination may occur.

  In the composition (3) or composition (4) of the present invention, if necessary, inorganic fillers (talc, calcium carbonate, calcined kaolin, etc.), organic fillers (fiber, wood powder, cellulose powder, etc.), lubricants (silicone) Oil, silicone gum, etc.), antioxidants (phenol, sulfur, phosphorus, lactone, vitamin, etc.), weather stabilizers, UV absorbers (benzotriazole, triazine, anilide, benzophenone, etc.) , Heat stabilizer, light stabilizer (hindered amine, benzoate, etc.), pigment, adsorbent (metal oxide (zinc oxide, magnesium oxide, etc.), metal chloride (iron chloride, calcium chloride, etc.), hydrotalcite, An aluminate or the like) may be added.

  As the injection molding machine for producing the molded article of the present invention, a screw having a shape intended to enhance kneading, for example, a machine equipped with a double flight shape, a dalmage shape, a barrier shape or the like is preferably used.

  By using an injection molding machine equipped with a screw having the above shape, the dispersibility of the nucleating agent is further increased, and the molding cycle and mechanical properties can be obtained more stably. When the dispersion of the nucleating agent in the composition is insufficient, for example, in the molding cycle, there may be variations in the releasability from the mold individually.

  The molded body of the present invention takes advantage of the above-mentioned excellent features, and is applied to an automobile driver airbag cover, a passenger airbag cover, a side airbag cover, a pillar airbag cover, a knee airbag cover, and a console. It can be suitably used for boxes, shift levers, various grips, and the like.

The following examples illustrate the invention in more detail.
[I] Physical property measurement method (1) Glass transition temperature (Tg)
Using a differential scanning calorimeter (DSC220C manufactured by Seiko Denshi Kogyo Co., Ltd .: input compensation DSC), the measurement was performed according to JIS K7121.
(2) Heat of crystallization (ΔHc)
Using a differential scanning calorimeter (DSC220C manufactured by Seiko Denshi Kogyo Co., Ltd .: input compensation DSC), the measurement was performed according to JIS K7122.
(3) Monomer unit content Propylene resin (A), propylene resin (B) used in composition (3) or composition (4), monomer unit content of rubber is infrared absorption spectrum Using FT-IR5200 (manufactured by JASCO Corporation), it was determined by a method using a calibration curve.

(4) Durability properties As durability properties, changes in tensile elongation at break (TE) before and after heating were confirmed. The change in physical properties was determined based on the following criteria by calculating the TE retention rate according to Equation 1.
(○: Retention rate is 80% or more, ×: Retention rate is less than 80%)
Retention rate (%) = {(TE after heating aging) / (TE before heating aging)} × 100 (Equation 1)
For flat molded products, side gate molds with a length of 150 mm, width of 90 mm, thickness of 2 mm, and gate area of 2 x 5 mm are installed in an injection molding machine (Toshiki Machine IS-100EN). The injection molding machine has a 36UDBW type screw. And A type screw head. Injection molding was carried out within a range of a molding temperature of 220 ° C., an injection pressure of 50 to 100 MPa, a mold temperature of 50 ° C., a cooling time of 30 seconds, and an injection rate of 20 to 40 g / second.
Prepare a JIS No. 3 test piece from a sample which was aged for 20 hours at 110 ° C. and a non-treated sample after being aged for 24 hours at 23 ° C. and 50% humidity after molding a flat molded product. did. The measurement was performed under the conditions of a distance between marked lines of 20 mm, a tensile speed of 200 mm / min, 23 ° C., and a humidity of 50%.

(5) Releasability Five or more shaped bodies having the shape shown in FIG. 1 were continuously molded under predetermined conditions, and the releasability was evaluated in two stages.
(○: No release failure, ×: Release failure)
In addition, the cooling time enabling stable continuous molding was evaluated every 5 seconds, and used as an index of the molding cycle. The shorter this time, the better the molding cycle.
Molding is performed by setting a mold for obtaining the molded body of FIG. 1 in an injection molding machine (FS160S25ASEN manufactured by Nissei Kogyo), cylinder set temperature 220 ° C., injection rate 90-110 g / second, injection time 15 seconds, cooling time 20 seconds, The air ejector pressure was 1.8 kg / cm ² , the mold temperature was 50 ° C., and conditions such that sink defects such as sink marks did not occur.

Example 1
Propylene-ethylene random copolymer A-1 (Sumitomo Chemical Nobrene Z144A, MFR = 25 g / 10 min, ΔHc = 82 mJ / mg, propylene content 96% by weight) as propylene resin (A) 90% by weight, nucleation After mixing 10% by weight of a sorbitol compound NC-4 (manufactured by Mitsui Chemicals) as an agent, it was melt-kneaded using a twin screw extruder to obtain composition (1) (MB).

  As propylene-based resin (B), propylene-ethylene random copolymer B-1 (Sumitomo Chemical Nobrene Z144CE4, MFR = 30 g / 10 min, ΔHc = 82 mJ / mg, propylene content 96 wt%) 97 wt% After mixing 3% by weight of MB as (1), it was melt kneaded at 220 ° C. using a single screw extruder equipped with a 100 mesh wire net to obtain composition (2) (PP-1).

  Ethylene-propylene random copolymer EPR (Sumitomo Chemical Esplen SPO E201, ML100 ° C. (1 + 4) = 43, Tg = −58 ° C., propylene content 53% by weight) 10% by weight, ethylene-propylene-ethylidene norbornadiene copolymer as rubber EPDM (Sumitomo Chemical Esplen EPDM E512P, ML 100 ° C. (1 + 4) = 90, Tg = −49 ° C., propylene content 30% by weight, ethylidene norbornadiene content 0.6% by weight) 40% by weight, PP- as the composition (2) 1 50% by weight was melt-kneaded with a Banbury kneader (BB-16 MIXER, manufactured by Kobe Steel) to obtain a composition (3) (composition I).

Before melt-kneading the composition (3) with a Banbury kneader, 0.1 parts by weight of an antioxidant (Irganox 1010 manufactured by Ciba Specialty Chemicals) is used as a mold release imparting agent with respect to 100 parts by weight of the composition (3). 0.05 part by weight of erucic acid amide (Nippon Seika Co., Ltd. Neutron S) was added.
Using the composition (3) thus obtained, a flat molded product was prepared under predetermined conditions, and the durability properties were confirmed. Similarly, the molded product shown in FIG. 1 was molded under a predetermined condition, and the release property was evaluated. The results are shown in Table 1.

Example 2
MB (1.5% by weight as the composition (1)), 48.5% by weight (B-1) as the propylene-ethylene random copolymer (B), 10% by weight EPR and 40% by weight EPDM (rubber) as the rubber (Kobe) The mixture was melt-kneaded with BB-16 MIXER (steel making) to obtain composition (4) (composition II). To the composition (4), the same amounts of the antioxidant and the release agent were added in the same manner as in Example 1.
The obtained composition (4) evaluated the same item by the same method as Example 1. The results are shown in Table 1.

Comparative Example 1
As a propylene-ethylene random copolymer (B), B-1 50% by weight, EPR 10% by weight and EPDM 40% by weight were melt-kneaded with a Banbury kneader (BB-16 MIXER, manufactured by Kobe Steel) to obtain a composition ( Composition III) was obtained. The same amount of antioxidant and mold release agent was added to the composition in the same manner as in Example 1.
The obtained composition evaluated the same item by the same method as Example 1. The results are shown in Table 1.

Comparative Example 2
49% by weight of B-1 as propylene-ethylene random copolymer (B), 10% by weight of EPR and 40% by weight of EPDM as rubber, 0.15% by weight of sorbitol compound NC-4 as a nucleating agent It was melt-kneaded by a Banbury kneader and a composition (Composition VI) was obtained. The same amount of antioxidant and mold release agent was added to the composition in the same manner as in Example 1.
The obtained composition evaluated the same item by the same method as Example 1. The results are shown in Table 1.

  From Examples and Comparative Examples, the molded products using Composition I and Composition II which are claims of the present invention are better than the molded products using Composition III which are not included in the claims of the present invention. Durable physical properties. Therefore, a nucleating agent is necessary to satisfy the durable physical properties that are the object of the present invention.

  In addition, the molded products using the composition I, the composition II, and the composition VI containing the same nucleating agent are confirmed to have a difference in releasability. The molded products using Composition I and Composition II, which are claims of the present invention, are more stable in mold release than the molded products using Composition VI not included in the claims of the present invention. Cooling time that can be molded is shortened. Therefore, in order to satisfy the stability of the molding cycle which is the object of the present invention, it is important to use the composition produced by the kneading method of the present invention.

  From the above results, in order to achieve the object of the present invention, it is important that the nucleating agent kneading conditions satisfy the claims.

It is a figure which shows the outline of a mold release evaluation molded article.

Claims (3)

A composition (1) is obtained by adding a nucleating agent to the propylene-based resin (A) and kneading, and a composition (1) is obtained by adding the propylene-based resin (B) to the composition (1) and kneading. A molded product obtained by obtaining 2), obtaining a composition (3) by adding rubber to the composition (2) and kneading, and molding the composition (3). A composition (1) is obtained by adding a nucleating agent to the propylene resin (A) and kneading, and a composition is obtained by adding the propylene resin (B) and rubber to the composition (1) and kneading. A molded product obtained by obtaining the product (4) and molding the composition (4). The molded article according to claim 1 or 2, wherein the molded article is an automobile airbag cover.