JP7749758B2 - Polypropylene resin composition, molded article, and molded article for automobile interior parts - Google Patents

Description

The present invention relates to a polypropylene resin composition, a molded article, and a molded article for automotive interior parts.

Automotive interior materials are made from molded resin compositions containing polypropylene resin with inorganic fillers and rubber added, but it is desirable that dust not adhere to the interior materials after molding or when they are delivered to the user. Since dust adhesion is primarily caused by static electricity, it is common to add antistatic agents to reduce the electrical resistance of the interior material's surface and allow static electricity to escape in order to make it less likely to adhere.

However, antistatic agents are easily adsorbed by inorganic fillers such as talc, making it difficult to achieve antistatic performance. If the amount of antistatic agent added is increased in order to achieve antistatic performance, the antistatic agent will vaporize and adhere to the windshield and other surfaces when the temperature inside the vehicle rises, such as in the summer, causing a problem known as fogging, in which the transparency of the glass is impaired. For these reasons, automotive interior materials are required to be free from dust adhesion, and furthermore, to ensure that the transparency of the vehicle's glass is not impaired by the adhesion of the antistatic agent.

Patent Document 1 discloses a resin composition for automotive interior materials with excellent antistatic and anti-fogging properties. The composition comprises 30 to 82 parts by weight of a propylene-ethylene block copolymer (component A) containing 5 to 20% by weight of a propylene-ethylene random copolymer with an ethylene content of 25 to 75% by weight, 10 to 40 parts by weight of talc (component B), and 8 to 30 parts by weight of an olefin-based elastomer (component C), for a total of 100 parts by weight, with the total of components B and C being 20 to 60 parts by weight. The composition also contains 0.3 to 0.45% by weight of an antistatic agent (component D) consisting of a mixture of monoglycerin fatty acid ester, diglycerin fatty acid ester, and alkyldiethanolamine.

Patent Document 2 discloses a polypropylene resin composition characterized by containing (A) 50 to 90 parts by weight of crystalline polypropylene resin, (B) 10 to 50 parts by weight of inorganic filler, (C) 0 to 40 parts by weight of rubber (where the total amount of components (A), (B), and (C) is 100 parts by weight), and (D) 0.01 to 3 parts by weight of palmitic acid diethanolamide.

Patent Document 3 discloses a polypropylene resin composition containing 100 parts by weight of a propylene polymerization material, 0.1 to 0.4 parts by weight of at least one ester compound selected from the group consisting of monoglycerin fatty acid esters and diglycerin fatty acid esters, 0.2 to 0.8 parts by weight of an antistatic agent containing 0.1 to 0.4 parts by weight of stearyldiethanolamine monostearate, 0.01 to 0.4 parts by weight of N,N'-di(hydroxyethyl)alkylamide, and 0.01 to 0.3 parts by weight of a hindered amine light stabilizer.

Japanese Patent Application Publication No. 11-323070 Japanese Patent Application Laid-Open No. 2002-212353 Japanese Patent Application Laid-Open No. 2014-201615

However, the polypropylene resin compositions described in the above patent documents do not have sufficient anti-fogging properties, and the amount of volatile organic compounds (VOCs), particularly aldehydes such as acetaldehyde and formaldehyde, emitted is not satisfactory.
The present invention aims to solve the above-mentioned problems in the prior art, and aims to provide a polypropylene resin composition that suppresses fogging and the generation of aldehydes without impairing antistatic properties.

As a result of extensive research to solve the above problems, the inventors discovered that alkyldiethanolamines and fatty acid esters of alkyldiethanolamines, which have traditionally been widely used as antistatic agents for polypropylene-based resins, are related to fogging and the generation of aldehydes, leading to the completion of the present invention.

That is, the present invention is as follows.
[1] For 100 parts by mass of polypropylene resin (A),
0 to 0.5 parts by mass of monoglycerin fatty acid ester (B),
A polypropylene resin composition comprising 0.01 to 1.0 parts by mass of a diglycerin fatty acid ester (C) and 0.001 to 0.2 parts by mass of a fatty acid diethanolamide (D),
A polypropylene-based resin composition characterized by being substantially free of alkyldiethanolamine and/or fatty acid ester of alkyldiethanolamine.
[2] The polypropylene resin composition according to [1], characterized in that it is substantially free of methanol derived from the component (D).
[3] For 100 parts by mass of polypropylene resin (A),
The polypropylene resin composition according to [1] or [2], wherein the components (B), (C), and (D) are blended in a total amount of 0.1 to 1.5 parts by mass.
[4] The polypropylene resin composition according to any one of [1] to [3], wherein the mass ratio of the total of the components (B) and (C) to the component (D) is [(B) + (C)]/(D) = 1/99 to 99/1.
[5] A molded article obtained by molding the polypropylene resin composition according to any one of [1] to [3].
[6] An injection-molded article obtained by molding the polypropylene resin composition according to any one of [1] to [3].
[7] A molded article for automobile interior parts obtained by molding the polypropylene resin composition according to any one of [1] to [3].

The polypropylene resin composition of the present invention and the molded articles produced by molding it can significantly suppress fogging and the generation of aldehydes while maintaining the antistatic properties necessary to prevent the adhesion of dust and other particles. Furthermore, because they do not become cloudy due to bleed-out, they can be preferably used as automotive interior parts.

The present invention will be described in detail below.
The polypropylene resin (A) constituting the polypropylene resin composition of the present invention can be appropriately selected from conventionally known polypropylene resins. Examples of such polypropylene resins (A) include propylene homopolymers, propylene-α-olefin random copolymers and propylene block copolymers, which are copolymers of propylene and an α-olefin other than propylene. The polypropylene resin (A) may also be modified with a polar group-containing monomer such as maleic anhydride. The polypropylene resin (A) may be used singly or in combination of two or more.

Preferred polypropylene resins (A) include propylene homopolymers, propylene-α-olefin random copolymers containing 30% by weight or less, preferably 5% by weight or less, of other α-olefin units, and propylene block copolymers having an n-decane extractable content of 10% by weight or less, particularly 8% by weight or less. Note that "α-olefin units" refer to structural units derived from α-olefins that constitute a polymer. In the present invention, α-olefins include ethylene.

Preferably, the other α-olefins forming the propylene-α-olefin random copolymer or propylene block copolymer are α-olefins other than propylene having 2 to 20 carbon atoms, such as ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-dodecene, 1-hexadecene, and 4-methyl-1-pentene. These α-olefins can be used alone or in combination of two or more.

Propylene block copolymers are typically obtained in multiple series-connected polymerization reactors, for example by producing propylene homopolymer in a first-stage polymerization reactor and producing propylene-α-olefin random copolymer rubber (typically propylene-ethylene random copolymer rubber) in the presence of propylene homopolymer in a second-stage polymerization reactor, and the propylene homopolymer and propylene-α-olefin random copolymer rubber are uniformly mixed. When a propylene block copolymer is used as polypropylene resin (A), the incorporation of a rubber component can be omitted if a sufficient amount of copolymer rubber is present in the propylene block copolymer.

The polypropylene resin (A) used in the present invention can be produced by a known method using a known solid titanium catalyst or metallocene catalyst.

The polypropylene resin (A) typically has a melt flow rate (MFR) measured in accordance with ASTM D1238 (230°C, under a load of 2.16 kg) of 0.1 to 300 g/10 min, preferably 1 to 100 g/10 min, and more preferably 50 g/10 min.

Monoglycerin fatty acid ester (B) is an ester compound obtained by a known method such as an esterification reaction between monoglycerin and a fatty acid, or a transesterification reaction between monoglycerin and a fatty acid lower alkyl alcohol ester. It is preferably a monoglycerin fatty acid ester compound obtained from monoglycerin and a fatty acid having 8 to 22 carbon atoms, but di- and tri-fatty acid esters may also be present. These may be distilled or used undistilled.

Fatty acids having 8 to 22 carbon atoms include saturated fatty acids such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, 12-hydroxystearic acid, arachidic acid, and behenic acid, and unsaturated fatty acids such as decenoic acid, undecenoic acid, dodecenoic acid, tetradecenoic acid, oleic acid, erucic acid, linoleic acid, linolenic acid, and ricinoleic acid. Among these, lauric acid, myristic acid, palmitic acid, and stearic acid are preferred from the standpoint of antistatic properties and bleeding properties, with palmitic acid and stearic acid being particularly preferred.

In the present invention, the monoglycerin fatty acid ester (B) is blended in an amount of 0 to 0.5 parts by mass per 100 parts by mass of the polypropylene resin (A), but from the viewpoint of antistatic properties and anti-fogging properties, it is preferably blended in an amount of 0.01 to 0.5 parts by mass, more preferably 0.05 to 0.4 parts by mass, and even more preferably 0.1 to 0.3 parts by mass.

Diglycerin fatty acid ester (C) is an ester compound obtained by known methods such as the esterification reaction between diglycerin and a fatty acid or the transesterification reaction between diglycerin and a fatty acid lower alkyl alcohol ester. It is preferably a mono-fatty acid ester compound of diglycerin obtained from diglycerin and a fatty acid having 8 to 22 carbon atoms, but di- and tri-fatty acid esters may also be present. These may be distilled or used undistilled.

The raw material diglycerin preferably contains 90% by mass or more of diglycerin, which is condensed with 2 moles of glycerin, but polyglycerin, which is condensed with 3 or 4 moles of glycerin, may also be present. The fatty acids having 8 to 22 carbon atoms can be the same as those used in monoglycerin fatty acid ester (B).

In the present invention, the diglycerin fatty acid ester (C) is blended in an amount of 0.01 to 1.0 part by mass per 100 parts by mass of the polypropylene resin (A), but from the viewpoint of antistatic properties and anti-fogging properties, it is preferably blended in an amount of 0.1 to 0.8 parts by mass, and more preferably 0.2 to 0.6 parts by mass.

The fatty acid diethanolamide (D) used in the present invention is a compound represented by the following general formula (1):

(wherein ^R1 represents an alkyl group or alkenyl group having 5 to 19 carbon atoms).

Specific examples of fatty acid diethanolamides (D) represented by the above general formula (1) include coconut fatty acid diethanolamide, lauric acid diethanolamide, tridecylic acid diethanolamide, pentadecylic acid diethanolamide, palmitic acid diethanolamide, heptadecylic acid diethanolamide, oleic acid diethanolamide, stearic acid diethanolamide, nonadecanoic acid diethanolamide, and arachidic acid diethanolamide. Among these, lauric acid diethanolamide is preferred from the viewpoint of anti-fogging properties. Fatty acid diethanolamides (D) can be used alone or in combination of two or more.

The fatty acid diethanolamide (D) as described above can be prepared by a conventionally known method, for example, by reacting a fatty acid or a fatty acid lower alkyl alcohol ester with diethanolamine. Therefore, in addition to the compound represented by general formula (1), a fatty acid diethanolamide and a fatty acid monoester, a fatty acid diester of a fatty acid diethanolamide and a fatty acid, a diethanolamine and a fatty acid monoester, a diethanolamine and a fatty acid diester, unreacted diethanolamine, unreacted fatty acid, and unreacted fatty acid lower alkyl alcohol ester may be present. However, since remaining unreacted fatty acid can cause odor and coloration, it is preferable to use a fatty acid lower alkyl alcohol ester, particularly a fatty acid methyl ester. The reaction ratio of the fatty acid or fatty acid lower alkyl alcohol ester to diethanolamine is preferably 0.9 to 1.1 moles, but is not limited to this.
To promote the reaction, a commonly known condensation reaction catalyst can be used, such as a titanium catalyst, a metal alcoholate catalyst, a tin catalyst, or a Bronsted acid catalyst.

In the present invention, the fatty acid diethanolamide (D) is blended in an amount of 0.001 to 0.8 parts by mass, preferably 0.005 to 0.5 parts by mass, and more preferably 0.01 to 0.2 parts by mass, per 100 parts by weight of the polypropylene resin (A).

Fatty acid diethanolamide (D) produced using fatty acid methyl ester contains methanol generated by the transesterification reaction. If residual methanol remains in the polypropylene resin composition, it tends to generate formaldehyde when heated during molding, so it is preferable to remove it by topping or other methods. The content of residual methanol can be measured by headspace gas chromatography or Method 3 of the Quasi-drug Ingredients Standards (QAS). It is preferable that the polypropylene resin composition contains substantially no residual methanol. Here, "substantially no residual methanol" means that the amount of residual methanol in the polypropylene resin composition is 10 ppm or less, preferably 5 ppm or less, and more preferably 1 ppm or less.

The polypropylene resin composition of the present invention is characterized by being substantially free of alkyldiethanolamine and/or alkyldiethanolamine fatty acid esters. By being substantially free of these antistatic agents, which have been widely used in the past, fogging and the generation of aldehydes can be significantly suppressed. Here, "substantially free" means that the content of these antistatic agents relative to the polypropylene resin composition is 10 ppm or less, preferably 1 ppm or less, and more preferably 0 ppm.

From the perspective of imparting excellent antistatic properties to the polypropylene resin composition, the total amount of components (B), (C), and (D) contained in the polypropylene resin composition is preferably in the range of 0.1 to 1.5 parts by mass per 100 parts by mass of the polypropylene resin. The preferred range for the content of the surfactant composition is 0.2 to 1.0 part by mass. By keeping it within this range, particularly excellent antistatic properties can be imparted.

The mass ratio of the total of components (B) and (C) to component (D) is preferably [(B) + (C)]/(D) = 1/99 to 99/1, but from the viewpoint of imparting antistatic properties, it is more preferably 51/49 to 95/5, and even more preferably 70/30 to 95/5. Furthermore, from the viewpoint of anti-fogging properties, it is preferably 49/51 to 5/95, and more preferably 5/95 to 30/70.

The polypropylene resin composition of the present invention can contain an inorganic filler to reinforce and increase the volume of the polypropylene resin composition. Examples of inorganic fillers include, but are not limited to, talc, calcium carbonate, barium sulfate, aluminum hydroxide, gypsum, dawsonite, simgon, radiolite, celite, novacite, asbestos, alumina, attapulgite, kaolin gray, volcanic ash, silica, wollastonite, diatomaceous earth, magnesium oxide, magnesium carbonate, feldspar powder, biotite, and magnesium silicate. Among these, talc is preferred. These inorganic fillers may be used alone or in combination.

The polypropylene resin composition of the present invention can be blended with various rubber components to impart flexibility, impact resistance, and other properties to the composition. Examples of rubber components include, but are not limited to, ethylene-α-olefin copolymer rubber, ethylene-α-olefin-non-conjugated diene copolymer rubber, natural rubber, isoprene rubber, polybutadiene rubber, isobutylene-isoprene copolymer rubber, acrylonitrile-butadiene copolymer rubber, styrene-butadiene copolymer rubber, styrene-isoprene copolymer rubber, silicone rubber, acrylic rubber, chloroprene rubber, and hydrogenated versions of the above rubbers. Of these, ethylene-α-olefin copolymer rubber and ethylene-α-olefin-non-conjugated diene copolymer rubber (hereinafter, the term "ethylene-based copolymer rubber" refers to both) are preferred. The above rubbers can be used alone or in combination of two or more.

The following describes ethylene-based copolymer rubbers that are preferably used as rubber components. Examples of α-olefins copolymerized with ethylene, preferably α-olefins having 3 to 10 carbon atoms, include propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, and 1-decene. Two or more of these α-olefins can be used in combination. From the perspective of impact resistance, the ethylene component content of ethylene-based copolymer rubber is 60 to 90 mol%, preferably 70 to 85 mol%.

Examples of non-conjugated dienes include dicyclopentadiene, 1,4-hexadiene, 1,9-decadiene, cyclooctadiene, norbornadiene, methylenenorbornene, ethylidenenorbornene, and 7-methyl-1,6-octadiene.

The iodine value of the ethylene-α-olefin-non-conjugated diene copolymer is preferably 5 to 50, more preferably 10 to 45. The Mooney viscosity (ML ₁₊₄ , 100°C) of the ethylene copolymer rubber is 10 to 100, preferably 20 to 60, from the viewpoints of dispersibility with polypropylene resin and impact resistance.

Ethylene-based copolymer rubber can be obtained by known polymerization methods, for example, by copolymerization in the presence of a vanadium-based, titanium-based, or metallocene-based catalyst.

In addition, in each process up to the production of molded articles for automotive interior parts from polypropylene-based resins, high-molecular-weight polymers such as poly(4-methyl-1-pentene), polystyrene, polybutadiene, or styrene-grafted polymers of polyisoprene, copolymer elastomers obtained by hydrogenating these polymers, polyesters, polyamides, and polycarbonates may be added depending on the intended use, as long as the effects of the present invention are not significantly impaired. The blending amount of these high-molecular-weight polymers is typically up to 5% by mass, and preferably up to 3% by mass.

In addition to the polypropylene resin, other polymers or elastomers, antistatic agents, and inorganic fillers, the polypropylene resin composition of the present invention may contain additives widely used in the fields of synthetic resins and synthetic rubbers, such as stabilizers against heat, oxygen, and light, weathering agents, crystal nucleating agents, lubricants, flame retardants, and plasticizers, depending on the intended use, as long as they do not significantly impair the effects of the present invention. In the present invention, pigments may also be blended into the polypropylene resin blended with these stabilizers or various additives.

Examples of stabilizers against heat and oxygen include phenolic antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants. Examples of weathering agents that prevent deterioration due to light include amine-based, triazole-based, benzophenone-based, benzoate-based, nickel-based, and salicylic acid-based compounds. Examples of crystal nucleating agents include sorbitol-based, phosphorus-based, rosin-based, organic phosphate ester metal salts, and carboxylic acid metal salts. Examples of lubricants include fatty acid amides, higher alcohols, and polyethylene wax. Examples of flame retardants include phosphate-based, melamine-based, phosphorus-based, halogen-based, and non-halogen-based compounds. Examples of plasticizers include phthalate-based, fatty acid-based, adipate-based, trimellitate-based, epoxy-based, and polyester-based compounds.

Pigments can be inorganic or organic. Inorganic pigments have an inorganic color-producing portion and are composed of simple elements, as well as oxides, sulfides, and sulfates of elements such as Zn, Pb, Ti, Sb, Cd, Fe, As, Mg, Al, Co, and Cr. Organic pigments have an organic color-producing portion and include azo pigments, polyazo pigments, azine pigments, copper phthalocyanine pigments, dioxane pigments, and quinacridone pigments. Dispersing aids (such as fatty acid metal salts, naphthenic acid metal salts, surfactants, silicone oil, and lecithin) may be used to improve pigment dispersibility in polypropylene.

When molding the polypropylene resin composition of the present invention, it can be produced by blending the main polypropylene resin with the components (B) to (D) of the present invention using conventional methods. Other polymers, inorganic fillers, pigments, and other additives may also be blended. For example, the components (B) to (D) of the present invention, and optionally inorganic fillers, pigments, and other additives, are blended with powdered or pelletized polypropylene resin and other polymers, and the blend is mixed using a Henschel mixer, tumbler mixer, or the like. The resulting mixture is then melt-kneaded and pelletized in a single- or twin-screw kneading extruder. The pellets obtained are then processed into molded articles using an injection molding machine. If the polypropylene resin composition has an MFR of less than 5 g/10 min, its moldability in injection molding is poor and it is unsuitable for use in automotive interior parts. Furthermore, if it exceeds 150 g/10 min, its impact resistance is poor and it is unsuitable for use in automotive interior parts.

The molded article of the present invention is a molded article obtained by molding the polypropylene resin composition of the present invention by a known molding method, and examples thereof include injection molded articles, press molded articles, vacuum molded articles, vacuum press molded articles, pressure molded articles, foam molded articles, and extrusion molded articles.

The molded article of the present invention is preferably an injection-molded article. Examples of injection molding methods include general injection molding, injection foam molding, supercritical injection foam molding, ultra-high speed injection molding, injection compression molding, injection press molding, gas-assisted injection molding, sandwich molding, sandwich foam molding, and insert-outsert molding.

Preferred uses of the molded article of the present invention include automotive interior parts, such as door trims, pillars, instrument panels, consoles, rocker panels, armrests, door panels, and spare tire covers.

The molded article for automotive interior parts of the present invention can be produced by injection molding the polypropylene resin composition described above. The molding temperature is generally 150 to 350°C, preferably 170 to 250°C. Molding temperatures above 350°C can cause deterioration of the resin composition and molding defects, while temperatures below 150°C can result in poor appearance and molding defects. A mold temperature in the range of 10 to 60°C is preferred. While a mold temperature above 60°C can produce a molded article with excellent surface finish and rigidity, it lengthens the molding cycle and reduces productivity. Conversely, setting the mold temperature below 10°C not only results in significant warping and shrinkage, making it difficult to obtain a satisfactory molded article, but also makes condensation more likely to form on the mold, which can accelerate mold corrosion. This is also unsuitable from the perspective of the energy costs associated with cooling.

The present invention will now be described using examples, but the present invention is not limited to these examples. Unless otherwise specified, blend amounts are expressed in parts by mass.

[Synthesis of fatty acid diethanolamide (D)]
Synthesis Example 1
A glass autoclave was charged with 1,360 g of methyl laurate, 650 g of diethanolamine, and 19.6 g of 28% sodium methylate. The autoclave was purged with nitrogen and stirred. The pressure was reduced to -0.090 MPa or less, and the temperature was raised to 80°C. After heating, the reaction was carried out at -0.090 MPa or less for 10 hours, followed by vacuum topping at 80°C for 4 hours, synthesizing 1,808 g of the target lauric acid diethanolamide (D1). The residual methanol in the product was 450 ppm. The residual methanol was measured according to Method 3 of the Quasi-drug Raw Materials Standards (QDS).

Fatty acid diethanolamides (D2) to (D5) were synthesized in the same manner as in Synthesis Example 1, except that the type of raw material fatty acid ester and the time of reduced pressure topping were changed as shown in Table 1. The amount of residual methanol is shown in Table 1.

[Production of injection molded article]
Examples 1 to 9 and Comparative Examples 1 to 5
Using Novatec MA1B manufactured by Japan Polypropylene Corporation as polypropylene resin (A), the types and amounts of components (B) to (D) and other components shown in Tables 1 and 2 below were blended in a twin-screw extruder (TEM26SS manufactured by Toshiba Machine Co., Ltd.) and melt-kneaded (screw rotation speed: 250 rpm, cylinder temperature: 200°C). The extrudate was cooled and solidified with cold water and cut to obtain resin component compound pellets.
The prepared compound was molded at a molding temperature of 190°C using a hybrid injection molding machine FNX140 manufactured by Nissei Plastic Industrial Co., Ltd. to prepare flat test plates measuring 150 mm x 150 mm x 3 mm.

Measurements and evaluations of each evaluation item were performed using the methods below. The results are shown in Tables 2 and 3.

(1) Evaluation of antistatic properties The prepared test plates were left to stand for 14 days under conditions of 23°C and 50% humidity, and then the surface resistivity was measured using a Hiresta UP MCP-HT450 manufactured by Mitsubishi Chemical Analytech Co., Ltd. Here, based on previous knowledge, the surface resistivity effective for preventing adhesion of dirt and dust to a molded product was set to 1 x ¹⁰ (log Ω/□) or less.

(2) Evaluation of Anti-fogging Properties Two 25 mm x 100 mm x 3 mm thick pieces were cut out from the test plate to serve as samples for evaluating fogging properties. The fogging properties were evaluated using a Thomas Scientific fogging tester (constant temperature oil bath) with the glass container heated to 100°C for 20 hours. After the heat treatment, the glass plate with the fogging attached was removed and left to stand for 1 hour under conditions of 23°C and 50% humidity. The total light transmittance of the glass plate was measured using a HM-150 L2 haze meter manufactured by Murakami Color Technology Research Co., Ltd., to evaluate the anti-fogging properties. Here, fogging that does not impair visibility while riding in a car was defined as less than 5%.

(3) Evaluation of Bleeding Property A test piece was placed in an oven set at 60° C. for 200 hours, and after being taken out, the appearance was visually observed and evaluated according to the following criteria.
◯: No bleeding observed with the naked eye. △: Bleeding observed with the naked eye. ×: Bleeding easily observed with the naked eye, and the composition cannot be used for practical purposes.

(4) Acetaldehyde and formaldehyde emission amounts The acetaldehyde emission amounts were measured by the following method using test pieces of 80 mm x 100 mm cut out from the flat plate molded article obtained by the above-mentioned [Production of injection molded article].
(i) The test piece was sealed in a sampling bag with a volume of 10 L, and the bag was filled with pure nitrogen gas. After that, the pure nitrogen gas was removed, and the gas in the sampling bag was replaced with nitrogen gas. This operation was repeated twice.
(ii) The sampling bag was filled with 4 L of pure nitrogen gas, and the cock of the sampling bag was closed. The sampling bag was placed in an oven, and a Teflon (registered trademark) sampling tube was attached to the tip of the cock and extended to the outside of the oven. In this state, heat treatment was carried out at 65°C for 2 hours.

(iii) Sampling and measurement of acetaldehyde and formaldehyde One liter of the sample gas prepared in (ii) above was sampled in a simulated adsorption tube while heated to 65°C, and the remaining sample gas was then sampled in its entirety into a 2,4-dinitrophenylhydrazine (DNPH) cartridge at a sampling rate of 0.4 L/min. The sampled cartridge was subjected to elution with acetonitrile, and the resulting eluate was used to measure the components eluted from the cartridge using a high-performance liquid chromatograph (HPLC; manufactured by Waters, model: Ultra Performance Liquid Chromatography Aquiy).

The amount of acetaldehyde and formaldehyde emitted (the amount of acetaldehyde and formaldehyde emitted from one test piece of a specified size, unit: μg/test piece) was calculated using the calibration curve of the standard substance for that component. Note that the detection limit for acetaldehyde and formaldehyde using this evaluation method is 0.060 μg/test piece, and when the amount of acetaldehyde or formaldehyde emitted was 0.060 μg/test piece or less, it was recorded as "n.d." (below detection limit).

As shown in Table 2, all of the polypropylene resin compositions of Examples 1 to 9 were excellent in antistatic properties and anti-bleeding properties. In addition, fogging and the generation of aldehydes were significantly suppressed.
In contrast, as shown in Table 3, the polypropylene resin compositions of Comparative Examples 1 to 4 containing alkyldiethanolamine or fatty acid esters of alkyldiethanolamine exhibited fogging and generation of aldehydes.

Claims (7)

For 100 parts by mass of the polypropylene resin (A),
Monoglycerin fatty acid ester (B) 0.05 to 0.5 parts by mass,
A polypropylene resin composition comprising 0.01 to 1.0 parts by mass of a diglycerin fatty acid ester (C) and 0.001 to 0.8 parts by mass of lauric acid diethanolamide (D),
A polypropylene-based resin composition characterized by being substantially free of alkyldiethanolamine and/or fatty acid ester of alkyldiethanolamine. The polypropylene resin composition according to claim 1, characterized in that it is substantially free of methanol derived from component (D). For 100 parts by mass of the polypropylene resin (A),
3. The polypropylene resin composition according to claim 1, wherein the components (B), (C) and (D) are blended in a total amount of 0.1 to 1.5 parts by mass. The polypropylene resin composition according to any one of claims 1 to 3, wherein the mass ratio of the sum of the (B) and (C) components to the (D) component is [(B) + (C)]/(D) = 1/99 to 99/1. A molded article obtained by molding the polypropylene resin composition according to any one of claims 1 to 4. An injection-molded article obtained by molding the polypropylene resin composition according to any one of claims 1 to 4. A molded article for automotive interior parts obtained by molding the polypropylene resin composition according to any one of claims 1 to 4.