KR20120116160A - Olefin thermoplastic elastomers composition - Google Patents

Abstract

PURPOSE: An olefin-based thermoplastic elastomer composition is provided to have excellent tensile strength and elongation at high temperatures, and to have excellent impact resistance at low temperatures. CONSTITUTION: An olefin-based thermoplastic elastomer composition comprises a polypropylene-based resin, a modified polypropylene, an olefin-based copolymer elastomer, a styrene-based copolymer elastomer, and organized nanoclay. The composition has a high-temperature tensile strength at 80 °C is 60 kgf/cm^2 or more, and a high-temperature tensile elongation is 700% or more. The polypropylene-based resin is a propylene polymer, or a copolymer of polypropylene and aliphatic A-olefin or aromatic olefin. The flow index polypropylene-based resin measured at 230 °C and 2.16 Kg is 1-90 g/10min.

Description

Olefin thermoplastic elastomer composition

The present invention relates to an olefinic thermoplastic elastomer composition and a vehicle airbag cover part manufactured using the same.

Thermoplastic elastomer resins have excellent processability such as plastics, have elastomeric properties such as rubber, and do not include a crosslinking process performed during processing of rubber, and thus are applied to a wide range of fields such as automobiles, electrical electronics, and office equipment. In particular, olefinic thermoplastic elastomer resins have excellent mechanical properties, excellent tensile properties, and excellent low-temperature impact strength, and thus are widely used as automotive interior and exterior materials.

However, since the olefin thermoplastic elastomer resin does not have high temperature tensile properties, there is a limitation in applying it as an airbag cover part for automobiles. To be used as an automotive airbag cover part, the cover must be reliably torn during airbag deployment testing. The airbag deployment test is carried out in accordance with the airbag deployment test, the temperature of the room temperature, high temperature (about 80 ℃) and low temperature (about -35 ℃) mechanical properties at these temperatures is very important. .

As a method for improving low temperature properties, the method disclosed in Korean Patent Publication No. 10-2008-0005352 is a method of maintaining a low temperature impact strength by adding a crosslinking agent in an olefin elastomer composition. The above method may be applied to improve low temperature physical properties of the olefin-based thermoplastic elastomer resin used as an automobile airbag cover, but has a weak tensile property at a high temperature.

Tensile properties (ex. Tensile elongation) at high temperatures (80 ° C.) of olefinic thermoplastic elastomer resins correlate with airbag deployment properties, and if the tensile strength and tensile elongation are low, the cover tears before the airbag is fully developed (expanded). In addition, since the tearing problem occurs in parts other than the originally designed tearing area, it is not possible to guarantee the stability of the vehicle occupant. Therefore, a method for controlling the high temperature physical properties of the olefin-based thermoplastic elastomer resin is required.

In order to reinforce tensile strength at high temperature, a method of increasing the content of polypropylene resin or adding an existing inorganic filler such as talc is used. However, in the above case, the low temperature impact elongation and the low temperature impact elongation are deteriorated. Falling phenomenon occurs.

In addition, in order to make up for the above problems, a method of increasing the content of the olefin copolymer elastomer and the styrene copolymer elastomer has been proposed. However, in this case, although the tensile elongation and low temperature impact strength is high, there is a problem that the high temperature tensile strength is low.

An object of the present invention is to provide an olefinic thermoplastic elastomer composition which has excellent tensile strength and tensile elongation at high temperature and excellent impact strength at low temperature, which can be used as an automobile airbag cover part.

The present invention relates to an olefinic thermoplastic elastomer composition comprising a polypropylene resin, a modified polypropylene, an olefin copolymer elastomer, a styrene copolymer elastomer and an organically treated nanoclay.

Hereinafter, the olefin thermoplastic elastomer composition of this invention is demonstrated in detail.

The olefinic thermoplastic elastomer composition according to the invention can preferably be used as an automobile airbag cover part.

In the present invention, the olefinic thermoplastic elastomer composition may have a high temperature tensile strength of 60 kgf / cm ^{2 or} more, measured at 80 ° C., and a high temperature tensile elongation of 700% or more. The high temperature tensile strength and tensile elongation are the values measured by the ASTM D638 method. The upper limit of the high temperature tensile strength and the tensile elongation is not particularly limited. For example, the upper limit of the high temperature tensile strength is 150 kgf / cm ² or less, preferably 100 kgf / cm ² or less, more preferably 80 kgf / It may be cm ² or less, the upper limit of the high temperature tensile elongation may be 1500% or less, preferably 1000% or less.

The olefinic thermoplastic elastomer composition according to the present invention comprises a polypropylene resin, a modified polypropylene, an olefin copolymer elastomer, a styrene copolymer elastomer and an organically treated nanoclay.

The polypropylene resin according to the present invention is a polymer containing propylene as a main component.

In the present invention, a polypropylene polymer may be used as the polypropylene resin, or a copolymer of propylene and an aliphatic alpha (α) -olefin and / or an aromatic olefin may be used. In this case, at least one selected from the group consisting of ethylene, 1-butene, 1-pentene and 1-hexene may be used as the alpha (α) -olefin. Can be used.

Specifically, as the polypropylene resin, a polypropylene polymer or a copolymer of one or more olefins selected from the group consisting of ethylene, 1-butene, 1-pentene and 1-hexene may be used, and more specifically, At least one selected from the group consisting of polypropylene copolymers, propylene-alpha-olefin copolymers, and propylene-ethylene-alpha-olefin copolymers. Here, the copolymer may be a random or block copolymer.

In the present invention, the polypropylene resin may have a melt index of 1 to 90 g / 10 min, measured at 230 ° C. and 2.16 Kg load, and preferably 10 to 50 g / 10 min. If the melt index is out of the above range, there is a fear that problems occur during injection molding.

In addition, the content of the polypropylene resin in the present invention may be 20 to 60 parts by weight based on 100 parts by weight of the total composition. If the content is less than 20 parts by weight, the tensile strength and hardness may be lowered. If the content is more than 60 parts by weight, the low temperature impact strength may be lowered.

The modified polypropylene according to the present invention can be used to improve the dispersibility of the nanoclay in the polypropylene resin, specifically, the modified polypropylene acts on the layers of the organically treated layered nanoclay to form the nanoclay as a polypropylene-based It can be made to be uniformly dispersed on the resin.

In the present invention, as the type of the modified polypropylene, one or more reactors selected from the group consisting of acrylic acid, maleic acid, maleic anhydride, carboxylic acid, and hydroxyl groups may be used in the main chain or the terminal of the polypropylene. Preferably, acrylic acid is formed at the terminal of the polypropylene.

When using modified polypropylene having acrylic acid formed at the terminal of the polypropylene, the melt index of the modified polypropylene may be 1 to 80 g / 10 min, preferably 10 to 50 g / 10 min. In this case, the acrylic acid content in the modified polypropylene may be 0.1 to 15% by weight, preferably 2 to 10% by weight. When the acrylic acid content is less than 0.1% by weight, there is a fear that a sufficient reaction may not occur during the preparation of the resin, and when the acrylic acid content is more than 15% by weight, the reactivity may be increased and the moldability may decrease as the viscosity of the final composition is increased.

The content of the modified polypropylene in the present invention may be 0.1 to 10 parts by weight based on 100 parts by weight of the total composition. It is excellent in the dispersibility of the nanoclay within the content range.

The olefin copolymer elastomer according to the present invention can improve the high temperature tensile elongation of the olefin thermoplastic elastomer composition to be produced. In the present invention, one or more selected from the group consisting of an alpha-olefin copolymer and an olefin copolymer may be used as the olefin copolymer elastomer. Here, the alpha-olefin-based copolymer or the olefin-based copolymer may be a random copolymer prepared by copolymerizing two or more mono olefins as partially amorphous or amorphous.

Specifically, as the olefin-based copolymer elastomer of the present invention, at least one selected from the group consisting of ethylene-butene copolymer, ethylene-octene copolymer, ethylene-propylene copolymer and derivatives thereof can be used, An ethylene-octene copolymer or an ethylene-propylene copolymer may be used.

In the present invention, the melt index of the olefin-based copolymer elastomer may be 0.1 to 50 g / 10 min, preferably 0.3 to 20 g / 10 min. If the melt index is less than 01 g / 10 min, the melt index of the final composition may be lowered and moldability may decrease during product processing. If the melt index exceeds 50 g / 10 min, the heat resistance may decrease.

In the present invention, the density of the olefin-based copolymer elastomer may be 0.85 to 0.90 g / cm ³ , preferably 0.86 to 0.88 g / cm ³ . If the said density is less than 0.85 g / cm <^3> , there exists a possibility that a tensile strength may fall, and when it exceeds 0.90 g / cm < ³ >, there exists a possibility that an impact strength may fall.

In addition, the pattern viscosity at 100 ° C of the olefin-based copolymer elastomer of the present invention ML1 +4 may be 10 to 100, preferably 20 to 70. If the said pattern viscosity is less than 10, there exists a possibility that a moldability may fall, and when it exceeds 100, there exists a possibility that heat resistance may fall.

In the present invention, the content of the olefin copolymer elastomer may be 5 to 40 parts by weight, preferably 10 to 35 parts by weight based on 100 parts by weight of the total composition. If the content is less than 5 parts by weight, it is difficult to obtain a high temperature tensile elongation improving effect of the composition to be produced, there is a fear that the role as an elastomer may be lowered. If the content exceeds 40 parts by weight, the hardness is lowered to maintain the form as an automobile airbag cover It can be difficult to do.

Styrene-based copolymer elastomer according to the present invention may serve to improve the low temperature impact properties of the elastomer composition.

In the present invention, the styrene-based copolymer elastomer may be a copolymer elastomer of styrene and an aliphatic unsaturated hydrocarbon having 2 to 10 carbon atoms.

Specifically, the styrene copolymer elastomer is selected from the group consisting of styrene-butadiene-styrene copolymer, styrene-isoprene-styrene copolymer, styrene-ethylene-propylene-styrene copolymer and styrene-ethylene-propylene-styrene copolymer One or more may be used, preferably styrene-ethylene-butylene-styrene.

In the present invention, the content of the styrene-based copolymer elastomer may be 5 to 40 parts by weight based on 100 parts by weight of the total composition. If the content is less than 5 parts by weight, there is a risk that it is difficult to obtain the low-temperature impact improvement effect of the composition to be produced, if it exceeds 40 parts by weight, the flow characteristics are lower, which is not suitable for injection molding, and the hardness is also lowered form of the product There is a risk of becoming difficult to maintain.

The organically treated nanoclay according to the present invention may serve to improve tensile strength and tensile elongation at high temperatures of the elastomeric composition.

In the present invention, the organically treated nanoclay may use a layered clay mineral treated with organic onium ions, and specifically, tetra alkyl ammonium salt, tetra alkyl phosphonium salt, ammonium salt containing alkyl and aryl, or alkyl and aryl. Clay minerals containing an intercalated ammonium salt may be used. At this time, one or more selected from the group consisting of montmorillonite, hectorite and saponite may be used as the clay mineral.

The content of the organically treated nanoclay in the present invention may be 0.5 to 15 parts by weight, preferably 3 to 13 parts by weight based on 100 parts by weight of the total composition. If the content is less than 0.5 parts by weight, there is a risk that the use of the organic nano-clay treated is insignificant to increase the tensile strength and elongation at high temperature, and if the content exceeds 15 parts by weight, the nanoclay due to agglomeration phenomenon Since the clay may not be sufficiently separated between layers, the tensile elongation at high temperature may be lowered, and the surface may not be smooth.

The olefin-based thermoplastic elastomer composition of the present invention is a lubricant, antioxidant, light stabilizer, mold release agent, pigment, antistatic agent, crosslinking agent, antibacterial agent, processing aid, metal deactivator, friction wear and coupling agent, etc. It may further include one or more selected from the group consisting of.

The present invention also relates to a method for producing an olefinic thermoplastic elastomer molded article comprising the step of mixing and melt kneading the olefinic thermoplastic elastomer composition described above.

 In the present invention, the olefinic thermoplastic elastomer composition may include a polypropylene resin, a modified polypropylene, an olefin copolymer elastomer, a styrene copolymer elastomer, and an organically treated nanoclay. The type and content of the polypropylene-based resin, modified polypropylene, olefin-based copolymer elastomer, styrene-based copolymer elastomer and organically treated nanoclay may be used as the above-described types and contents.

In the present invention, the olefin-based thermoplastic elastomer composition is mixed in a mixer after working in a twin-screw extruder, a single-screw extruder, a roll mill, a kneader, or a banbury mixer. Melt kneading may be performed using one of a variety of compound processing machines such as a mixer). The melt kneaded composition may be prepared into pellets using a pelletizer.

The invention also relates to automotive airbag cover parts made using the olefinic thermoplastic elastomer composition described above.

The olefinic thermoplastic elastomer composition according to the present invention has excellent tensile strength and tensile elongation at high temperature, and excellent impact strength at low temperature, and therefore can be preferably used for automobile airbag cover parts and the like.

In the present invention, it is possible to provide an olefinic thermoplastic elastomer composition which can be used as an automobile airbag cover part by having excellent tensile strength and tensile elongation at high temperature and excellent impact strength at low temperature.

Hereinafter, the present invention will be described in more detail with reference to the following examples and comparative examples, but the scope of the present invention is not limited by the following examples.

Example 1

Impact copolymer with polypropylene resin with melt index of 25 g / 10 min. 40 parts by weight of impact copolymer polypropylene resin (SEETE M1600, LG Chem.), Modified polypropylene with melt index of 20 g / 10 min. And acrylic acid content of 6 weight. Ethylene-octene copolymer (LC170, LG Chemical) having an melt index of 1.1 g / 10 min and a density of 0.870 g / cm ³ (olefinic copolymer elastomer) 1) 30 parts by weight, 15 parts by weight of a styrene-ethylene-butadiene-styrene copolymer (Kraton G1657, Kraton Polymer Co., Ltd.) having a melt index of 5 g / 10 min and a density of 0.89 g / cm ³ with a styrene copolymer elastomer; In a twin-screw extruder, a composition containing 10 parts by weight of montmorillonite (Cloisite 15A, Southern clay products) substituted with dimethyl dihydrogenated tallow tetra ammonium salt interlayered with nanoclay was mixed well by a mixer. Melting Serial to make a pellet was prepared in the olefin-based thermoplastic elastomer resin.

Example 2

Except that 30 parts by weight of an olefin copolymer elastomer, an ethylene-propylene copolymer elastomer (KEP-020P, Kumho Polychem) (olefin copolymer elastomer-2) having a pattern viscosity ML 1 + 4 of 25 at 100 ° C. was used. Resin was prepared in the same manner as in Example 1.

Example 3

A resin was prepared in the same manner as in Example 1, except that 50 parts by weight of polypropylene resin, 15 parts by weight of olefin copolymer elastomer-1 and 20 parts by weight of styrene copolymer elastomer were used.

Comparative Example 1

The resin was prepared in the same manner as in Example 1, except that 70 parts by weight of the polypropylene resin and 15 parts by weight of the olefin copolymer elastomer-1 were used without using modified polypropylene and nanoclay.

Comparative Example 2

A resin was prepared in the same manner as in Example 1, except that 50 parts by weight of the polypropylene resin, 20 parts by weight of the olefin copolymer elastomer-1 and 20 parts by weight of the styrene copolymer elastomer were not used. It was.

Comparative Example 3

Except not using modified polypropylene and nanoclay, except that 50 parts by weight of polypropylene resin, 20 parts by weight of olefin copolymer elastomer-1, 20 parts by weight of styrene copolymer elastomer and 10 parts by weight of talc were used. Resin was prepared in the same manner as in 1.

Test Example

In order to test the physical properties of the olefinic thermoplastic elastomer pellets prepared in Examples 1 to 3 and Comparative Examples 1 to 3, a specimen for measuring physical properties was manufactured using an injection molding machine, and tensile strength, impact strength, and hardness were measured in the following ASTM standard. It evaluated based on. The results are shown in Table 1 below.

(1) high temperature tensile strength and elongation

It was measured according to the ASTM D638 method, the test temperature was set to 80 ℃, the crosshead speed was set to 200 mm / min.

(2) low temperature Izod impact strength

It was measured according to the ASTM D256 method and the test conditions were measured under 40 ℃ conditions.

(3) hardness

Measured according to ASTM D2240 method, the unit is Shore D scale.

division Example Comparative example One 2 3 One 2 3 Furtherance Polypropylene 40 40 50 70 50 50 Modified polypropylene 5 5 5 - - - Olefin Copolymer Elastomer-1 30 - 15 15 20 20 Olefin Copolymer Elastomer-2 - 30 - - - - Styrene Copolymer Elastomer 15 15 20 15 20 20 Organic Nanoclay 10 10 10 - 10 - Talc - - - - - 10 Properties High Temperature Tensile Strength (Kgf / cm2) 65 66 67 49 55 52 High Temperature Tensile Elongation (%) 850 830 790 470 530 510 Low Temperature Impact Strength (Kgf / cm2) No break No break No break 28.4
(break) No break 32.2
(break) Shore D 41 42 45 58 43 44

As shown in Table 1, the olefin-based thermoplastic elastomer resins of Examples 1 to 3 have excellent high temperature tensile elongation and high temperature tensile strength compared to the comparative examples, while the low temperature impact strength measured value has a No break. In the case of Comparative Example 2 without using the modified polypropylene, the low temperature impact strength measured value has a No break, but the high temperature tensile elongation and the high temperature tensile strength were low.

Claims (24)

An olefinic thermoplastic elastomer composition comprising a polypropylene resin, a modified polypropylene, an olefin copolymer elastomer, a styrene copolymer elastomer, and an organically treated nanoclay.
The method of claim 1,
An olefinic thermoplastic elastomer composition having a high temperature tensile strength of 60 kgf / cm ² or more and a high temperature tensile elongation of 700% or more, measured at 80 ° C.
The method of claim 1,
The polypropylene resin is an propylene polymer or an olefin thermoplastic elastomer composition which is a copolymer of polypropylene and an aliphatic alpha (α) -olefin or an aromatic olefin.
The method of claim 3, wherein
The alpha (α) -olefin is at least one olefinic thermoplastic elastomer composition selected from the group consisting of ethylene, 1-butene, 1-pentene and 1-hexene.
The method of claim 1,
Polypropylene resin is an olefinic thermoplastic elastomer composition having a flow index of 1 to 90 g / 10 min measured at 230 ℃ and 2.16 Kg load.
The method of claim 1,
The content of the polypropylene resin is 20 to 60 parts by weight based on 100 parts by weight of the total composition of the olefin thermoplastic elastomer composition.
The method of claim 1,
The modified polypropylene is an olefinic thermoplastic elastomer composition in which at least one reactor selected from the group consisting of acrylic acid, maleic acid, maleic anhydride, carboxylic acid and hydroxyl groups is formed at the main chain or the terminal of the polypropylene.
The method of claim 1,
The modified polypropylene is an olefinic thermoplastic elastomer composition in which acrylic acid is formed at the terminal of the polypropylene.
The method of claim 8,
The content of acrylic acid formed at the end of the polypropylene is 0.1 to 15% by weight olefin-based thermoplastic elastomer composition.
The method of claim 1,
The content of the modified polypropylene is 0.1 to 10 parts by weight with respect to 100 parts by weight of the total composition of the olefin thermoplastic elastomer composition.
The method of claim 1,
The olefin copolymer elastomer is an olefin thermoplastic elastomer composition of at least one selected from the group consisting of ethylene-butene copolymer, ethylene-octene copolymer, ethylene-propylene copolymer and derivatives thereof.
The method of claim 1,
The olefin copolymer elastomer has an olefin thermoplastic elastomer composition having a flow index of 0.1 to 50 g / 10 min and a density of 0.85 to 0.90 g / cm ³ measured at 230 ° C. and a 2.16 Kg load.
The method of claim 1,
The olefin copolymer elastomer has an olefin thermoplastic elastomer composition having a pattern viscosity of ML1 + 4 of 10 to 100 at 100 ° C.
The method of claim 1,
The content of the olefin copolymer elastomer is 5 to 40 parts by weight with respect to 100 parts by weight of the total composition of the olefin thermoplastic elastomer composition.
The method of claim 1,
Styrene-based copolymer elastomer is an olefin-based thermoplastic elastomer composition is a copolymer elastomer of styrene and aliphatic unsaturated hydrocarbon having 2 to 10 carbon atoms.
The method of claim 1,
Styrene-based copolymer elastomer is an olefin-based at least one selected from the group consisting of styrene-butadiene-styrene copolymer, styrene-isoprene-styrene copolymer, styrene-ethylene-propylene-styrene copolymer and styrene-ethylene-propylene-styrene copolymer Thermoplastic Elastomer Composition.
The method of claim 1,
The content of the styrene copolymer elastomer is 5 to 40 parts by weight based on 100 parts by weight of the total composition of the olefin thermoplastic elastomer composition.
The method of claim 1,
The organically treated nanoclay is an olefinic thermoplastic elastomer composition which is a tetra mineral ammonium salt, a tetra alkyl phosphonium salt, an ammonium salt containing alkyl and aryl or an ammonium salt containing alkyl and aryl intercalated clay mineral.
The method of claim 17,
The clay mineral is at least one olefinic thermoplastic elastomer composition selected from the group consisting of montmorillonite, hectorite and saponite.
The method of claim 1,
The content of the organically treated nanoclay is 0.5 to 15 parts by weight of the olefinic thermoplastic elastomer composition based on 100 parts by weight of the total composition.
The method of claim 1,
Olefinic thermoplastic elastomer further comprising at least one selected from the group consisting of lubricants, antioxidants, light stabilizers, mold release agents, pigments, antistatic agents, crosslinkers, antibacterial agents, processing aids, metal deactivators, friction wear agents and coupling agents Composition.
Of an olefinic thermoplastic elastomer molded article comprising mixing and melt kneading an olefinic thermoplastic elastomer composition containing a polypropylene resin, a modified polypropylene, an olefinic copolymer elastomer, a styrene copolymer elastomer and an organically treated nanoclay. Manufacturing method.
The method of claim 22,
Melt kneading is a method for producing an olefin-based thermoplastic elastomer molded article is carried out using a compound processing equipment comprising a twin screw extruder, single screw extruder, roll mill, kneader or short-barrier mixer.
An automobile airbag cover part manufactured using an olefinic thermoplastic elastomer composition containing a polypropylene resin, a modified polypropylene, an olefin copolymer elastomer, a styrene copolymer elastomer, and an organically treated nanoclay.