JP3364429B2 - Thermoplastic elastomer composition for powder slush molding - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic elastomer composition for powder slush molding, and more specifically, it has excellent powder fluidity required for powder slush molding, is easy to remove from the skin after molding, and has a tensile strength. And a thermoplastic elastomer composition suitable for powder slush molding in which the change of the surface state due to heat aging is small and the volatilization of low molecular weight organic substances is small.

[0002]

2. Description of the Related Art As a powder molding method using a soft powder material, a powder slush molding method using a soft vinyl chloride resin powder is an instrument panel, a console box,
Widely used in the skin of automobile interior parts such as door trim. This is because it has a soft feel, can be provided with leather textures and stitches, and has good designability such as a large degree of freedom in design.

Unlike other molding methods such as injection molding and compression molding, this molding method does not apply a shaping pressure. Therefore, in order to uniformly attach the powder material to a mold having a complicated shape, the powder material is powdered. Since it has excellent fluidity and the powder adhered to the mold melts and flows even under no pressure to form a film, it is also a condition that the melt viscosity is low. Further, it has been necessary to cool the mold and release the molded skin easily from the mold.

As one method for improving this, Japanese Patent Application Laid-Open No. 7-82433 discloses a polypropylene resin and a specific styrene thermoplastic elastomer in a weight ratio of 70/3.
It has been proposed to mix and mix the mixture in a ratio of 0 to 30/70 before use. Here, the styrene-based thermoplastic elastomer is styrene having a styrene content of 20% by weight or less.
Ethylene butylene / styrene block copolymer, styrene / ethylene propylene / styrene block copolymer having a styrene content of 20% by weight or less, and styrene content of 20
The composition is selected from hydrogenated styrene-butadiene rubber in an amount of not more than 5% by weight, and has a good compatibility with polypropylene resin and is suitable for powder molding.

[0005]

However, even in this composition, when the polypropylene resin and the hydrogenated styrene-butadiene rubber are mixed, the hydrogenated styrene-butadiene rubber is finely dispersed in the polypropylene resin, so that the deterioration of the physical properties is small and the material for the skin is small. Suitable for However, since the hydrogenated styrene-butadiene rubber is inferior in oil absorption ability, there is a drawback that the oligomer component in the composition migrates to the surface and has tackiness.
For this reason, since the thermoplastic elastomer powder pulverized for powder slush molding also has adhesiveness, it is easy to block and the powder fluidity is deteriorated. Also, when the epidermis is released from the mold, the releasability may deteriorate.

Further, as an improvement of the above, a thermoplastic elastomer composition for powder slush molding containing a polypropylene resin, a hydrogenated styrene-butadiene rubber, an elastomer having an excellent oil absorbing ability, and a process oil has been proposed. However, the slush-molded sheet with this composition has a defect that tackiness and gloss are generated on the surface of the sheet due to heat aging at 110 to 120 ° C. Further, a low molecular weight organic matter volatilizes from the composition and adheres to the window glass. There was a problem that it solidified and became cloudy.

The present invention solves the above problems, and in particular, reduces the change in the surface state due to heat aging,
Another object of the present invention is to provide a thermoplastic elastomer composition suitable for powder slush molding in which low volatilization of low molecular weight organic substances is suppressed to prevent clouding of glass.

[0008]

That is, according to the invention of claim 1 of the present application, it is a powdery thermoplastic elastomer composition used for powder slush molding, comprising at least a polypropylene resin and a hydrogenated styrene butadiene rubber,
A thermoplastic elastomer composition for powder slush molding containing an elastomer having an excellent oil absorbing ability, a process oil, a fatty acid amide, and a bloom inhibitor.

In the invention according to claim 2 of the present application, the amount of the fatty acid amide added is 100 parts by weight of a polymer comprising a polypropylene resin, hydrogenated styrene butadiene rubber, and an elastomer having an excellent oil absorbing ability, and process oil added. To 0.05 to 5 parts by weight with respect to the thermoplastic elastomer composition for powder slush molding.

In the invention according to claim 3 of the present application, the bloom inhibitor is polyethylene glycol, a phenol resin,
A thermoplastic elastomer composition for powder slush molding, which is an ethylene oxide adduct of an ethylene-vinyl alcohol copolymer, and at least one polymer selected from a mixture of these polymers and silica.

In the invention according to claim 4 of the present application, the amount of the bloom inhibitor added is polypropylene polymer, hydrogenated styrene butadiene rubber, and a polymer made of an elastomer having an excellent oil absorbing ability, to which process oil is added.
The thermoplastic elastomer composition for powder slush molding is 0.1 to 10 parts by weight based on parts by weight.

In the invention according to claim 5 of the present application, the thermoplastic resin composition for powder slush molding has a polypropylene resin and hydrogenated styrene-butadiene rubber in a weight ratio of 80/20 to 20/80.

In the invention according to claim 6 of the present application, there is provided a thermoplastic elastomer composition for powder slush molding in which 20 to 250 parts by weight of an elastomer having an excellent oil absorbing ability is mixed with 100 parts by weight of hydrogenated styrene-butadiene rubber. .

According to the invention of claim 7 of the present application, the elastomer excellent in oil absorption is styrene-ethylene-propylene-
Styrene block copolymer (SEPS), styrene / ethylene butylene / styrene block copolymer (SEB)
S), an olefin crystal / ethylene butylene / olefin crystal block copolymer, ethylene propylene rubber, and an ethylene / octene copolymer, which are at least one polymer selected from powdery slush molding thermoplastic elastomer compositions.

The invention according to claim 8 of the present application is the thermoplastic elastomer composition for powder slush molding, wherein 5 to 200 parts by weight of the process oil is mixed with 100 parts by weight of the elastomer having an excellent oil absorbing ability.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The polypropylene resin used in the present invention may be either a polypropylene homopolymer or a block or random copolymer with an α-olefin, but particularly a block or random copolymer using ethylene as an α-olefin. Polymers are preferred from the viewpoint of flexibility of the molded product. Further, in order to use for powder slush molding without applying pressure, it is 230 ° according to JIS K7210 as an index of melt fluidity of polypropylene resin.
It is necessary that the MFR (melt flow rate) measured with a load of 2.16 kgf at C is 20 g / 10 minutes or more. The polypropylene resin is a polymer whose main chain is cleaved by heat or oxidation, and has a property different from that of polyethylene which is crosslinked and hardened, and its main chain is cleaved by an organic peroxide, and the molecular weight is reduced.

Further, hydrogenated styrene butadiene rubber (H-SBR) has excellent compatibility with polypropylene resin, and when it is kneaded with polypropylene resin, it becomes flexible and a thermoplastic elastomer composition which is resistant to bending and whitening is obtained. To be The styrene content of the hydrogenated styrene-butadiene rubber is preferably 30% by weight or less, and 5 to 15% by weight is suitable for obtaining a highly flexible skin. HS
BR differs from SEBS, which is a block copolymer, in that styrene-butadiene rubber in which styrene and butadiene are randomly copolymerized is hydrogenated.
A typical example is the Dynaron series, a product manufactured by Japan Synthetic Rubber Co., Ltd. Polypropylene resin and HS
The mixing amount with BR is 80/20 to 20/80 in weight ratio. When the polypropylene resin is large, the molded skin becomes hard, and when the polypropylene resin is small, the tensile strength is lowered.

An elastomer excellent in oil absorption is compatible with polypropylene resin and has a property of absorbing a process oil and an oligomer component in the composition. The styrene / ethylene butylene / styrene block copolymer
Polymer (SEBS) or styrene-ethylene propylene
Styrene block copolymer thermoplastic elastomer such as styrene block copolymer (SEPS), olefin crystal / ethylene butylene / olefin crystal block copolymer (CEBC), ethylene propylene rubber (EPR), and ethylene / octene copolymer ( There is POE).

The above SEBS is obtained by hydrogenating a styrene / butadiene / styrene block copolymer (SBS). The Crayton G series manufactured by Ciel Chemical Co., and the Tuftec H series manufactured by Asahi Kasei Co., Ltd. Can be mentioned. In this SEBS, the strength increases as the styrene content increases, but the flexibility decreases. Also,
In the case of SEBS, the styrene hard segment may be aggregated by melting during slush molding, and it may be difficult to obtain a smooth sheet-shaped molded product. Therefore, the styrene content is preferably 40% by weight or less.

SEPS is a styrene / isoprene / styrene block copolymer (SIS) hydrogenated.
Septon, which is a product manufactured by Kuraray Co., Ltd., is typical. SE
Similar to BS, the flexibility decreases as the styrene content increases, so the styrene content is preferably 40% by weight or less.

The above-mentioned elastomer having excellent oil absorption ability is
The compatibility with polypropylene resin is inferior to that of H-SBR, and when kneaded and added to polypropylene resin, they are dispersed in a size of μm unit, so that the tensile properties tend to be deteriorated. However, polypropylene resin has HS
When BR and process oil are added, H-SBR
Has inferior oil absorption ability, and thus the oligomer component in the composition migrates (bleeds) to the surface and has adhesiveness, and the elastomer powder crushed using this for powder slush molding also has adhesiveness, making blocking easy As a result, the fluidity of the powder and the releasability of the skin from the mold are lacking. When an elastomer having an excellent oil absorbing ability is added to this, bleeding can be prevented by absorbing the oligomer component and oil in the composition.

The added amount of the elastomer having an excellent oil absorbing ability is 20 to 250 parts by weight with respect to 100 parts by weight of H-SBR. If it is less than 20 parts by weight, the oligomer component and oil in the composition cannot be sufficiently absorbed, and
If it exceeds 0 part by weight, the dispersion with the polypropylene resin becomes poor and the tensile properties are deteriorated.

Further, in the present invention, the addition of the process oil has the effects of being absorbed by the elastomer component in the composition to lower the melt viscosity and also lowering the hardness of the skin and providing flexibility. The above process oil is used for rubber, paraffin type, naphthene type,
Although it is classified as an aromatic type, a paraffin type is preferable due to its compatibility with the elastomer component. The addition amount is preferably 5 to 200 parts by weight with respect to 100 parts by weight of the elastomer having an excellent oil absorbing ability. If it exceeds 200 parts by weight, the tensile properties are deteriorated, and if it is less than 5 parts by weight, the melt viscosity does not decrease and the skin becomes hard.

The fatty acid amide used is RCONHR '.
(R and R ′ are both hydrogen or an alkyl group having 10 or more carbon atoms.) And are synthesized from various fatty acids and ammonia or an alkylated amine. Saturated fatty acid monoamide, unsaturated fatty acid monoamide,
Examples include substituted amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, and substituted ureas. Since these fatty acid amides have a long-chain alkyl group and an amide group with strong polarity in the molecule, they have a surface-active effect, so they also function as lubricants and dispersants, and also have the effect of preserving low-molecular-weight substances inside the molded sheet. , Prevents the generation of tackiness and gloss after heat aging.

Specific examples of the above fatty acid amides include saturated fatty acid monoamides such as lauric acid amide, palmitic acid amide, stearic acid amide and behenic acid amide; unsaturated fatty acid monoamides such as oleic acid amide and erucic acid amide; and N-stearyl. stearic acid amide, substituted amide, such as N- oleyl stearic acid amide, ethylenebis stearic acid amide, saturated fatty bisamides such as ethylene bis lauric acid Ami de, ethylenebis oleic acid amide, unsaturated bisamide, such as hexamethylene bis oleic acid amide , N-stearyl N'-stearyl urea, N-
Substituted urea such as butyl N′-stearyl urea may be mentioned.

The amount of the fatty acid amide added is 0.05 to 5 parts by weight per 100 parts by weight of polypropylene resin, hydrogenated styrene butadiene rubber, and a polymer comprising an elastomer having an excellent oil absorbing ability and process oil. If the amount is less than 0.05 parts by weight, adhesiveness and gloss are generated due to heat aging, while if the amount exceeds 5 parts by weight, fatty acid amide easily migrates to the surface of the molded sheet and the surface becomes white.

As the bloom inhibitor, at least one of polyethylene glycol, phenol resin, ethylene oxide adduct of ethylene-vinyl alcohol copolymer (CPO), and a mixture of these polymers and silica is used.
Species can be used, but CPO is particularly preferred.
This CPO has a structure called a comb polymer and has an appropriate compatibility with the elastomer matrix and the low molecular weight compounding agent, so that it has an effect of preventing blooming, particularly an effect of suppressing volatilization of the low molecular weight compounding agent.

The amount of the bloom inhibitor added is 0.1 to 10 parts by weight based on 100 parts by weight of polypropylene resin, hydrogenated styrene-butadiene rubber, and a polymer composed of an elastomer having an excellent oil absorbing ability and process oil. If the amount is less than 0.1 part by weight, the bloom preventing effect is small, whereas if it exceeds 10 parts by weight, the tensile strength is lowered.

As the heat stabilizer, those used for ordinary polyolefins can be used. Generally, phenol and a phosphorus-based antioxidant are used in combination, but they are not particularly limited. Further, as the light stabilizer, a hindered amine or benzotriazole type which is a radical scavenger may be used. Organic or inorganic pigments suitable for ordinary olefins are used. Further, lubricants such as fatty acid metal salts and fillers such as calcium carbonate and talc are added as needed.

Further, in the present invention, an organic peroxide can be added. This organic peroxide has the effect of cutting the main chain of the polypropylene resin, lowering the molecular weight of the polypropylene resin and increasing the melt fluidity, and giving the obtained thermoplastic elastomer composition high melt fluidity. . Here, the organic peroxide is not used as a crosslinking agent. Further, the thermoplastic elastomer composition obtained by kneading under heating does not substantially contain the organic peroxide due to thermal decomposition.

The above organic peroxide is usually rubber,
Diacyl peroxide used for resin crosslinking,
Peroxyester, diallyl peroxide, di-t
-Butyl peroxide, t-butyl cumyl peroxide, dicumyl peroxide, 2,5 -dimethyl-
2,5 -di (t-butylperoxy) -hexane-3,
1,3-bis (t-butylperoxy-isopropyl)
Benzene, 1,1-di-butylperoxy-3,3,5
-There is trimethylcyclohexane, etc., and 1 by thermal decomposition
It is preferable that the half-life per minute is 150 to 250 ° C.

In the process of kneading under heating at 120 to 250 ° C., the organic peroxide cuts the main chain of the polypropylene resin to lower the molecular weight, thereby giving the thermoplastic elastomer composition high melt fluidity. . The addition amount of the organic peroxide is 0.02 to 5.0% by weight in the thermoplastic elastomer composition, and if it is less than 0.02% by weight, the decomposition ability to cut the main chain of the polypropylene resin is small, It becomes impossible to impart high melt fluidity to the thermoplastic elastomer composition. On the other hand, if it exceeds 5.0% by weight, decomposition becomes excessive and mechanical properties such as tensile strength of the powder molded product deteriorate.

These compounds are mixed by mixing V-blender, tumbler, Henschel mixer with polypropylene resin, H-SBR, elastomer having excellent oil absorption ability, process oil, fatty acid amide, bloom inhibitor, pigment, stabilizer, lubricant and the like. It is dry-blended using a material supply hopper and the process oil is 120-250.
It is injected from a vent port whose temperature is adjusted to a range of ° C, melt-kneaded and pelletized by a twin-screw extruder.

Further, by using a kneader which is a closed type kneader, a Banbury mixer, etc., H- which is an elastomer component.
After adding process oil to SBR and an elastomer having an excellent oil absorbing ability, kneading and pelletizing, organic pellets and other compounding agents are mixed with the pellet and polypropylene resin, and the temperature is in the range of 120 to 250 ° C. It is also possible to melt-knead and pelletize with a single-screw or twin-screw extruder whose temperature is adjusted.

The melt flow rate (MFR), which is the melt viscosity of the obtained pellets, is 2 according to JIS K7210.
It is preferably 5 g / 10 minutes or more under a load of 50 ° C. and 0.325 kgf. If it is less than this range, the melt fluidity of the composition tends to be low, and pinholes tend to occur in the skin.

Polypropylene resin, H-SBR, process oil, elastomer having excellent oil absorbing ability, fatty acid amide, pellets obtained from blending mainly containing a bloom inhibitor, or organic peroxide added to these pellets. The pellets are finely pulverized by using an impact type fine pulverizer such as a turbo mill, a pin mill and a hammer mill. At this time, it is usually frozen and pulverized using liquid nitrogen. Further, depending on the composition, the molten resin can be pulverized by spraying with a spray or a disk atomizer and cooling. The crushed product passes through a sieve having a particle size of at least 1,000 μm with a sieve or the like, and has an average particle size of 100 to 80.
Particles having a particle size of 0 μm are collected, and an organic or inorganic powdery property improving agent is added and mixed to be used for powder slush molding.

Next, powder slush molding is performed using the elastomer composition. In this molding, the composition is dropped into the mold heated to a temperature higher than the melting point of the composition mainly by gravity, the mold is inverted after a lapse of a predetermined time, and the excess composition is collected in a recovery box. The composition adheres to the surface of the mold as a layer and melts with time to form a skin layer.
Then, the mold is cooled to remove the skin layer from the mold,
This is repeated.

As a method of heating the mold, a method of circulating oil or putting it in a hot air oven is generally used. The oil circulation makes it easy to adjust the mold temperature due to the pipe arrangement, but it is heated only from the mold surface. On the other hand, when a hot air oven is used, it is possible to heat from both the mold surface and the back surface of the molded product, but since hot air is often set to 300 ° C or higher in consideration of productivity, the heat on the back surface of the molded product is It is necessary to consider the prescription and conditions so as not to cause oxidative deterioration.

The hot air method is effective when performing powder slush molding in multiple layers (2 to 3). That is, the first powder, which is the outermost layer, is slush molded into a heated mold,
The powder is applied a second time in the semi-molten state and slush-molded a third time if necessary, followed by heat melting. In this case, since heat transfer is insufficient by heating only from the mold surface side, a hot-air stove system that allows heating from the back surface of the molded product is often used.

[0040]

Next, the present invention will be described in more detail with reference to specific examples. Examples 1 to 6 and Comparative Examples 1 to 4 A material obtained by dry blending the materials shown in Table 1 excluding the process oil with a tumbler was supplied from a raw material supply hopper of a twin-screw extruder (PCM45, manufactured by Ikegai Steel Co., Ltd.), The process oil was extruded at 200 ° C. into pellets while being injected from the vent port. And turbo mill T250-
4J (manufactured by Turbo Kogyo Co., Ltd.) was charged with pellets dipped in liquid nitrogen and pulverized, and only a portion passing through a 1,000 μm sieve was collected.

Next, powder slush molding was performed using the above powder composition. As the powder slush molding method, first, 150 mm × 150 mm × with a leather grain pattern
A 0.9 mm plate was heated to 250 ° C. in an oven, and about 800 g of the above powder composition was placed on the plate for 10 minutes to allow the powder composition to adhere thereto.
It was heated in an oven adjusted to 00 ° C for 60 seconds, taken out of the oven and cooled with water, and an epidermis having a thickness of about 0.8 mm was demolded. The surface evaluation and the haze value of the above skin after heat aging were measured, and the obtained results are also shown in Table 1.

(Evaluation of surface after heat aging of epidermis) The surface of the epidermis after heat aging was evaluated by heat aging for 200 hours in an oven adjusted to 120 ° C, and the tackiness of the surface was measured with tentacles. The superiority and inferiority of the glossiness was judged visually. The surface without stickiness and glossiness was marked with O, the one with some surface was marked with Δ, and the one with many was marked with X.

(Haze Value Test Method) The haze value test method is a method in which the skin is heated at 100 ° C. and a volatile low molecular weight substance is attached to a transparent glass plate, and the haze ratio is examined. As the test equipment, use the one specified in DIN75201, put a skin of about 150 cm ² in a 1 liter beaker, and
After heating for 20 hours in an oil bath at 00 ° C, the transmittance was measured with a parallel light transmittance measuring machine. The cloud value is a value obtained by subtracting the transmittance after heating from the transmittance of the glass plate before heating in percent (%).

[0044]

[Table 1]

As a result, in the examples, since the fatty acid amide and the bloom inhibitor were used in combination, the surface of the epidermis after heat aging did not show tackiness and glossiness, and the haze value was small. It can be seen that the change of the surface state is small and the volatilization of low molecular weight organic substances is reduced to prevent the glass from fogging. On the other hand, in the comparative example, only one of the fatty acid amide and the bloom inhibitor is used, so the surface of the epidermis after heat aging shows tackiness and glossiness, and the cloud value becomes high and low molecular weight organic compounds Volatilization is seen.

[0046]

As described above, in the inventions according to claims 1 to 8 of the present application, at least a polypropylene resin, a hydrogenated styrene-butadiene rubber, an elastomer having an excellent oil absorbing ability, a process oil, a fatty acid amide, and A thermoplastic elastomer composition for powder slush molding containing a bloom inhibitor, which has an excellent effect of reducing the change in surface state due to heat aging and reducing the volatilization of low molecular weight organic substances to prevent glass fogging. is doing.

─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Katsuyuki Hioki 4-1-21, Hamazoe-dori, Nagata-ku, Kobe Mitsuboshi Belting Co., Ltd. (56) Reference JP-A-10-30036 (JP, A) JP Flat 7-82433 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08L 9/06 C08L 23 / 10-23 / 16

Claims (8)

(57) [Claims] 1. A powdered thermoplastic elastomer composition used for powder slush molding, comprising at least polypropylene resin, hydrogenated styrene butadiene rubber, and
A thermoplastic elastomer composition for powder slush molding, which comprises an elastomer having an excellent oil absorption ability, a process oil, a fatty acid amide, and a bloom inhibitor. 2. A fatty acid amide is added in an amount of 0.05 to 5 with respect to 100 parts by weight of a polymer comprising a polypropylene resin, hydrogenated styrene-butadiene rubber, and an elastomer having an excellent oil absorbing ability and process oil. The thermoplastic elastomer composition for powder slush molding according to claim 1, which is parts by weight. 3. The bloom inhibitor is at least one polymer selected from polyethylene glycol, a phenol resin, an ethylene oxide adduct of an ethylene-vinyl alcohol copolymer, and a mixture of these polymers and silica. 1. The thermoplastic elastomer composition for powder slush molding according to 1. 4. The amount of the bloom inhibitor added is 0.1 to 100 parts by weight of polypropylene resin, hydrogenated styrene-butadiene rubber, and a polymer made of an elastomer having an excellent oil absorbing ability, and process oil. The thermoplastic elastomer composition for powder slush molding according to claim 1, which is 10 parts by weight. 5. The thermoplastic elastomer composition for powder slush molding according to claim 1, wherein the polypropylene resin and the hydrogenated styrene-butadiene rubber have a weight ratio of 80/20 to 20/80. 6. An elastomer having an excellent oil absorbing ability is 20 to 2 per 100 parts by weight of hydrogenated styrene-butadiene rubber.
The thermoplastic elastomer composition for powder slush molding according to claim 1, which is mixed in an amount of 50 parts by weight. 7. The styrene / ethylene propylene / styrene block copolymer (S
EPS), styrene / ethylene butylene / styrene block copolymer (SEBS), olefin crystal / ethylene butylene / olefin crystal block copolymer, ethylene propylene rubber, and at least one polymer selected from ethylene / octene copolymer. The thermoplastic elastomer composition for powder slush molding according to claim 1 or 4. 8. The thermoplastic elastomer composition for powder slush molding according to claim 1, wherein 5 to 200 parts by weight of the process oil is mixed with 100 parts by weight of the elastomer having an excellent oil absorbing ability.