JP3365674B2 - Soft resin composition and molded article obtained by extrusion-molding the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soft resin composition excellent in strength, heat resistance, molding processability and improved in stickiness of a molded article and a profile extrusion molded article.

[0002]

2. Description of the Related Art A composition comprising a polyolefin resin and a substantially amorphous ethylene-α-olefin copolymer is known as a resin composition having improved impact strength or a soft polyolefin resin composition. is there. A composition comprising a polyolefin resin and a partially crystalline ethylene-α-olefin copolymer is also known as a soft polyolefin resin composition having improved impact strength or softness.

Generally, in order to obtain a flexible composition in the above system, it is necessary to increase the amount of the ethylene-α-olefin copolymer rubber compounded. Heat resistance and mechanical strength tend to decrease. In order to solve such a problem, a polyolefin-based composition in which a rubber component is partially and completely dynamically crosslinked, that is, a so-called thermoplastic elastomer composition has been proposed. These thermoplastic elastomer-like compositions give excellent flexibility and heat resistance, but include a step of crosslinking the rubber component, so that the production method thereof is limited,
In addition, the manufacturing method tends to be complicated.

Further, for the purpose of providing a softer composition, a softening agent and the like are used as a polyolefin resin and rubber-like ethylene-
A composition comprising an α-olefin copolymer and a method of blending it with the above-mentioned thermoplastic elastomer-like composition have been proposed, but when the copolymer is substantially amorphous, it is mechanically The strength and the heat resistance tend to be remarkably lowered, and when the copolymer is partially crystalline, the heat resistance is not particularly lowered, but the softening agent has a composition due to the crystallinity. There was an unavoidable problem of moving to the surface of the object.

As a method for solving the above problems, a composition using a specific ethylene-α-olefin copolymer having a very high viscosity (Japanese Patent Laid-Open No. 20224/1993).
4) is disclosed. Although this composition has improved strength and heat resistance as compared with a conventional blend of a polyolefin resin and an ethylene-α-olefin copolymer, it is difficult to say enough and further improvement has been desired. . Further, there is a problem in that a special device having a very high kneading ability is required for producing these compositions.

[0006]

The present invention provides a soft resin composition which is flexible and has excellent strength, heat resistance, molding processability and does not have the problem of stickiness, without resorting to complicated methods such as dynamic crosslinking. Providing and a molded body made therefrom.

[0007]

Means for Solving the Problems As a result of intensive studies to solve the above problems, a specific ethylene-α-olefin copolymer rubber, a specific hydrogenated block copolymer, a polypropylene resin and a mineral oil rubber The present invention has been accomplished by finding that a composition comprising a softening agent for use is suitable for the above purpose.

That is, the object of the present invention is: (a) 90 to 30 parts by weight of an ethylene-α-olefin copolymer rubber having an MFR of 1 g / 10 minutes or less (b) a general formula A-B-A having the following characteristics: (A here
Is a polymer block of a monovinyl-substituted aromatic hydrocarbon, B
Is an elastomeric polymer block of conjugated dienes)
Hydrogenated derivatives of block copolymer represented by
0 parts by weight (a) MLMFR (condition 1 in Table 1 of JIS K7210)
0) is 0.1 g / 10 minutes or less (b) Polymer block B is 90 to 90% in the block copolymer.
60% by weight (c) polypropylene resin (a) + (b) total 1
10 to 120 parts by weight with respect to 00 parts by weight and (d) a total of 1 of (a) + (b) of a softening agent for mineral oil-based rubber
It can be solved by a soft resin composition characterized by being mixed in an amount of 20 to 100 parts by weight with respect to 00 parts by weight, and a molded body obtained by profile extrusion molding the composition.

Further, the performance is further improved by using an ethylene-α-olefin copolymer rubber satisfying the following characteristics as the component (a). (A) Decalin has an intrinsic viscosity [η] at 135 ° C. of 2.
5-10 dl / g (b) Shore A hardness is 90 or less (c) Maximum melting peak temperature by differential scanning calorimetry (DSC) is 100 ° C. or more (d) Tensile breaking strength is 100 kg / cm ² or more.

The present invention will be described in detail below. The ethylene-α-olefin copolymer rubber used in the present invention is a copolymer containing at least ethylene and α-olefin. As the α-olefin copolymerized with ethylene,
It is an α-olefin having at most 20, preferably 12 or less carbon atoms, and representative examples thereof include propylene, butene-1, hexene-1, 4-methylpentene-1 and octene-1. One or more of these are copolymerized with ethylene. The copolymerization ratio of α-olefin is usually 5 to 60 mol%.

In addition to these α-olefins, it is also possible to copolymerize a diene monomer. As the diene monomer, a diene monomer having 4 or more carbon atoms, for example, butadiene, 1,4-pentadiene, 1,4- and 1,5-hexadiene, 2,5-dimethyl-1,5
Chain diene compounds such as hexadiene and 1,4-octadiene, cyclic dienes such as dicyclopentadiene, cyclohexadiene, cyclooctadiene and dicyclopentadiene, alkenylnorbornenes such as 5-ethylidene- and 5-butylidene-2 -Norbornene, 2-methallyl-, and 2-isopropenyl-5-norbornene are used. Among these, ethylidene norbornene or dicyclopentadiene can be preferably used. The copolymerization ratio of the diene monomer is at most 10 mol%, especially 5
It is preferably less than or equal to mol%.

The ethylene-α-olefin copolymer rubber has an MFR of 1 g / 10 minutes or less, preferably 0.5 g / 1.
It is 0 minutes or less, particularly preferably 0.1 g / 10 minutes or less. When the MFR exceeds 1 g / 10 minutes, mechanical properties such as breaking strength of the resulting composition are deteriorated and a molded product is apt to be sticky.

Further, by using the ethylene-α-olefin copolymer rubber having the following characteristics, the breaking strength and heat resistance of the soft resin composition according to the present invention can be further improved. That is, the ethylene-
The intrinsic viscosity [η] of the α-olefin copolymer rubber at 135 ° C. is 2.5 to 10 dl / g, preferably 3 to 6 d.
1 / g. When it is less than 2.5 dl / g, the effect of improving the strength and heat resistance of the soft resin composition is small, and when it exceeds 10 dl / g, the fluidity and moldability are deteriorated, which is not preferable. Also,
In order to exhibit good flexibility and rubber elasticity, the Shore A hardness of the copolymer rubber is 90 or less, preferably 80 or less,
It is particularly preferably 75 or less. If the Shore A hardness exceeds 90, the hardness becomes too high and the flexibility of the soft resin composition becomes insufficient. The tensile breaking strength of the copolymer rubber is 100 kg / cm ² or more, preferably 150 kg in an uncrosslinked state.
/ Cm ² or more is required. If it is less than 100 kg / cm ² , the improvement in strength and heat resistance of the soft resin composition is small. Further, in order to improve the heat resistance, it is necessary that the copolymer rubber has a melting peak of polyethylene crystals at 100 ° C. or higher as measured by a differential scanning calorimeter (DSC). Those that do not have such a melting component have a small effect of improving heat resistance.

As a preferred method for producing a copolymer rubber having such characteristics, an example disclosed in JP-A-57-179207 can be mentioned. According to this method, ethylene and α-olefin are added in the presence of a Ziegler type catalyst,
50 ℃ in saturated or unsaturated hydrocarbons with 4 or less carbon atoms
A copolymer rubber suitable for the present invention can be prepared by copolymerizing in a slurry state at the following reaction temperatures. Unlike the conventional solution polymerization method, the present production method can easily produce a copolymer rubber containing a PE crystal component having a high melting point, unlike the conventional solution polymerization method.

A catalyst system suitable for such a method includes:
JP-A-47-34478 and JP-A-51-28189.
No. 52-151169 or No. 56-1190.
A catalyst system containing a solid component containing titanium, chlorine, and optionally magnesium, and an organoaluminum compound such as aluminum trialkyl, and a third component as required, as proposed in JP-A No. 56-15
1707, 57-14410 and 58-4.
5209 or 59-215304, and a solid component obtained by treating at least a compound containing Ti, Mg, and a halogen with a cyclic compound containing oxygen or nitrogen or a cyclic compound containing the compound or an organoaluminum compound, and an organoaluminum. A catalyst system consisting of a compound or a cyclic compound containing this and oxygen is suitable. Preferably, JP-A-5
6-151707 or 59-215304.

The component (b) used in the present invention is a hydrogenated derivative obtained by subjecting a block copolymer represented by the general formula ABA to a hydrogenation treatment. Is a monovinyl-substituted aromatic hydrocarbon polymer block, and B is an elastomeric polymer block of a conjugated diene. The monomeric monovinyl-substituted aromatic hydrocarbon constituting the polymer block A is preferably styrene,
α-Methylstyrene and the like are also used. Polymer block B
The conjugated diene monomer in is preferably butadiene or isoprene, or may be a mixture of both.

The block copolymer MLMFR is 0.1 g.
/ 10 minutes or less, preferably 0.01 g / 10 minutes or less. When the MLMFR exceeds 0.1 g / 10 minutes, mechanical properties such as breaking strength of the composition are remarkably lowered and the molded article tends to be sticky, which is not preferable.

Further, the polymer block B in the block copolymer accounts for 90 to 4 of the whole block copolymer.
It is preferably 0% by weight. When the content of the copolymer block B is less than 40% by weight, it becomes difficult to maintain the elastomeric property of the block copolymer after hydrogenation, and when it exceeds 90% by weight, the mechanical strength becomes poor, which is not preferable. . In the hydrogenated derivatives of these block copolymers, at least 5 of the conjugated double bonds in the polymer block B are
It is preferable that 0% or more, preferably 80% or more, is hydrogenated, and 25% or less of the aromatic unsaturated bond in the polymer block A is hydrogenated. As the hydrogenated derivative of such a block copolymer, commercially available septone (trade name) manufactured by Kuraray Co., Ltd., etc. can be used.

The mixing ratio of the component (a) and the component (b) is 90 to 30 parts by weight of the component (a) and 10 to 70 parts by weight of the component (b) ((a) + (b) = 100 parts by weight). , Component (b)
Is less than 10 parts by weight, mechanical properties such as rupture strength of the resulting soft resin composition are deteriorated and the molded article tends to be sticky, and if it exceeds 70 parts by weight, fluidity is remarkably reduced.
Moldability deteriorates. Further, the component (b) is the component (a)
Since it is more expensive than the above, it is not preferable from the economical point of view to blend the component (b) in an amount of more than 70 parts by weight.

The polypropylene resin used in the present invention includes propylene homopolymer, crystalline propylene-
Examples thereof include ethylene-block copolymers, crystalline propylene-ethylene-random copolymers and crystalline propylene-ethylene-butene-random copolymers.
The propylene resin has an MFR of 0.1 to 1000 g /
Min, preferably 1 to 100 g / 10 min. The amount of the polypropylene resin blended in the composition of the present invention is 10 to 100 parts by weight of the total of the component (a) and the component (b).
120 parts by weight, preferably 15 to 100 parts by weight.
If it is less than 10 parts by weight, mechanical properties such as breaking strength and moldability are inferior, and if it exceeds 120 parts by weight, flexibility is inferior, which is not preferable.

The mineral oil type rubber softening agent used as the component (d) of the present invention is added for the purpose of improving the fluidity and flexibility of the soft resin composition of the present invention.
The mineral oil-based softening agent for rubber is a mixture of an aromatic ring, a naphthene ring and a paraffin chain, and a paraffin chain having a carbon number of 50% or more is called a paraffin type. , Naphthene ring carbon number 30-45
% Are classified as naphthenes, and those with 30% or more aromatic carbons are called aromatics. Mineral oil type rubber softeners used as the component (d) of the present invention are paraffin type and naphthene type softeners in the above categories, and aromatic type softeners are dispersible with the component (b). Not preferable. In particular, as the component (d) of the present invention, a paraffinic one is preferable, and among paraffinic compounds, 5% or less of the aromatic ring component is particularly suitable.

The amount of the mineral oil-based softening agent to be added to the composition of the present invention is 20 to 100 parts by weight, preferably 30 to 80 parts by weight, based on 100 parts by weight of the total of the components (a) and (b). It is a department. A blending amount of less than 20 parts by weight is inferior in fluidity and flexibility of the composition, and a blending amount of more than 100 parts by weight causes stickiness in a molded article, which is not preferable.

In the soft resin composition of the present invention, talc, calcium carbonate, silica,
Inorganic fillers such as mica, calcium silicate, barium sulfate and carbon black can be added. It is appropriate that the compounding amount is usually 60 parts by weight or less based on 100 parts by weight of the total of the components (a), (b), (c) and (d) of the present invention. Further, if necessary, additives such as an antioxidant, an electrical property improving agent, a flame retardant, a processability improving agent, and a pigment can be added.

As the melt-kneading device, conventionally known ones such as an open type mixing roll, a non-open type Banbury mixer, an extruder, a kneader and a continuous mixer can be used. Among these, it is preferable to use a non-open type apparatus, and it is preferable to knead in an atmosphere of an inert gas such as nitrogen.

The composition of the present invention thus obtained can be molded by a commonly used thermoplastic resin molding machine, and molding methods such as extrusion molding, calendering, vacuum molding and injection molding can be applied. . Examples of fields of use of the soft resin composition obtained by the present invention include home electric appliance parts (packings, hoses), automobile interior / exterior parts (skin materials such as doors and instrument panels), and building material parts. Among them, since it is particularly excellent in profile extrudability, it is suitable for packing of doors of refrigerators, various gaskets for building materials, and the like.

[0026]

EXAMPLES The present invention will be described in more detail below with reference to Examples and Comparative Examples. [Measurement method] MLMFR was measured according to condition 10 of Table 1 of JIS K-7210 under conditions of a temperature of 200 ° C and a load of 10 kg. MFR was measured according to condition 14 of Table 1 of JIS K-7210 under the conditions of a temperature of 230 ° C. and a load of 2.16 kg. HLMFR is based on JIS K-7210,
The measurement was performed under the conditions of a temperature of 230 ° C. and a load of 21.6 kg. The melting point was press-molded at 230 ° C., conditioned at 23 ° C. for 1 week, and then measured at a temperature rising rate of 20 ° C./min using a DSC7 type manufactured by Perkin Elmer. Shore hardness is ASTM
It was measured according to D-676-49. The tensile breaking strength and breaking elongation were measured according to JIS K6301. The tensile speed was 200 mm / min. Permanent elongation is JIS
According to K6301. However, 10% between marked lines, 100% elongation for 10 minutes, and residual strain% after recovery for 10 minutes. For heat resistance, use TMA-50 manufactured by Shimadzu Corporation and raise the temperature at 10 ° C /
The temperature was measured when the needle penetrated to a depth of 100 μm under a load of 50 g for 50 minutes. A sheet having a stickiness of 30 mm was used to form a sheet having a thickness of 0.5 mm. After the sheet was left at 23 ° C. for 1 week, the surface of the sheet was evaluated by touching it by hand. Evaluation of profile extrusion property: Evaluation was performed according to the system A of Method A using the Garvey die described in ASTM D2230. The extruder used is a 20 mmφ single screw extruder.
The screw rotation speed was 70 rpm and the die temperature was 200 ° C.

[Raw materials] (1) Ethylene-α-olefin copolymer rubber EPM-1 (MFR: 0.03 g / 10 min, [η]: 4.
0 dl / g, melting peak temperature: 110 ° C, breaking strength: 2
00 kg / cm ² , Shore A: 65) EPM-2 (MFR: 0.7 g / 10 min, [η]: 2.2
No melting peak above dl / g, 100 ° C. Breaking strength:
65 kg / cm ² , Shore A: 57) EPM-3 (MFR: 1.1 g / 10 min, [η]: 1.9)
dl / g, melting peak temperature: 110 ° C., breaking strength: 75
kg / cm ² , Shore A: 65)

(2) Hydrogenated derivative of block copolymer Septon 4055 (MLMFR: manufactured by Kuraray Co., Ltd.)
Less than 0.01 g / 10 minutes (no flow), styrene content:
30 wt%) Kuraray Co., Ltd., Septon 2005 (MLMFR:
Less than 0.01 g / 10 minutes (no flow), styrene content:
20 wt%) Kuraray Co., Ltd., Septon 2043 (MLMFR: 1
3 g / 10 minutes, styrene content: 13% by weight) Kuraray Co., Ltd., Septon 2023 (MLMFR: 1)
g / 10 minutes, styrene content: 13% by weight)

(3) Polypropylene resin MA 810B (propylene homopolymer, MFR: 30 g / 10 minutes) manufactured by Showa Denko KK MG871 (propylene-ethylene random copolymer, ethylene content: 2) manufactured by Showa Denko KK .7 wt%,
MFR: 45 g / 10 minutes) Showa Denko KK-made, FD231 (propylene-ethylene random copolymer, ethylene content: 7 wt%, MF
R: 2 g / 10 minutes) Showa Denko KK, MD772H (propylene-ethylene random copolymer, ethylene content: 7 wt%, M
FR: 30g / 10 minutes)

(4) Softener for mineral oil rubber PW-380 manufactured by Idemitsu Kosan (paraffin oil, pour point: -15 ° C, kinematic viscosity at 98 ° C: 38.1 cs)
t, flash point: 300 ° C)

(5) Calcium carbonate (inorganic filler): NS1000 manufactured by Nitto Koka Kogyo Co., Ltd. Examples 1 to 7 Hydrogenated derivatives of ethylene-α-olefin copolymer rubber and block copolymer shown in Table 1 and polypropylene A predetermined amount of the system-based resin and the mineral oil-based softening agent was melt-kneaded using the same-direction twin-screw extruder KTX-37 (manufactured by Kobe Steel Ltd.) to obtain pellets. The obtained pellets were press-molded at 230 ° C. to obtain a physical property evaluation sample. The evaluation results are shown in Table 3. Moreover, the profile extrusion property was evaluated using the obtained pellets. The results are shown in Table 5.

Comparative Examples 1 to 5 Hydrogenated derivatives of ethylene-α-olefin copolymer rubbers and block copolymers shown in Table 2, polypropylene type resins and mineral oil type softening agents were co-axially biaxially extruded in predetermined amounts. Using a machine KTX-37 (manufactured by Kobe Steel Ltd.), melt kneading was performed to obtain pellets. The obtained pellets were press-molded at 230 ° C. to obtain a physical property evaluation sample. The evaluation results are shown in Table 4. Moreover, the profile extrusion property was evaluated using the obtained pellets. The results are shown in Table 6.

[0033]

[Table 1]

[0034]

[Table 2]

[0035]

[Table 3]

[0036]

[Table 4]

[0037]

[Table 5]

[0038]

[Table 6]

Comparative Example 6 15 parts by weight of EPM-1 and Septon 4 in Example 6 were used.
Pelletization was performed in the same manner as in Example 6 except that 055 was changed to 85 parts by weight. Compared with Example 6, the motor load of the extruder was extremely high, so the discharge amount could not be produced, and the productivity was significantly reduced. An attempt was made to make the obtained pellets into a sheet by using a sheet forming machine having a diameter of 30 mm. However, it was impossible to extrude the pellet due to a large increase in motor load and discharge pressure. Incidentally, the compositions of Examples 1 to 7 could be formed into a sheet without any problem.

[0040]

EFFECTS OF THE INVENTION According to the present invention, a soft resin composition which does not require complicated steps such as dynamic crosslinking and is excellent in balance of mechanical strength, heat resistance, flexibility and moldability by simply blending. Is obtained. Moreover, since this soft resin composition is particularly excellent in profile extrusion, the molded product obtained by profile extrusion molding is useful as various gaskets.

Front page continued (72) Inventor Hideo Katagiri 3-2 Chidori-cho, Kawasaki-ku, Kanagawa Prefecture Issue Showa Denko KK Kawasaki Plastics Research Laboratory (58) Fields investigated (Int.Cl. ⁷ , DB name) C08L 1/00-101/16 C08K 3/00-13/08 B29C 47/00

Claims (5)

(57) [Claims] 1. An ethylene-α-olefin copolymer rubber having an MFR of 1 g / 10 minutes or less (90 to 30 parts by weight) (b) a general formula A-B-A (where A:
Is a polymer block of a monovinyl-substituted aromatic hydrocarbon, B
Is an elastomeric polymer block of conjugated dienes)
Hydrogenated derivatives of block copolymer represented by
0 parts by weight (a) MLMFR (condition 10 in Table 1 of JIS K-7210) is 0.1 g / 10 minutes or less (b) Polymer block B is 90 to 90% in the block copolymer.
60% by weight (c) polypropylene resin (a) + (b) total 1
10 to 120 parts by weight with respect to 00 parts by weight and (d) a total of 1 of (a) + (b) of a softening agent for mineral oil-based rubber
A soft resin composition comprising 20 to 100 parts by weight with respect to 00 parts by weight. 2. The soft resin composition according to claim 1, wherein the ethylene-α-olefin copolymer rubber has the following characteristics: (a) Decalin has an intrinsic viscosity [η] at 135 ° C. of 2.
5-10 dl / g (b) Shore A hardness is 90 or less (c) Maximum melting peak temperature by differential scanning calorimetry (DSC) is 100 ° C. or more (d) Tensile breaking strength is 100 kg / cm ² or more. 3. The soft polymer according to claim 1, wherein A of the block copolymer represented by the general formula ABA is a styrene polymer block and B is an isoprene polymer block. Resin composition. 4. The soft resin composition according to any one of claims 1 to 3, wherein the mineral oil-based softening agent for rubber is a paraffin-based softening agent for rubber. 5. A molded product obtained by profile-extruding the soft resin composition according to any one of claims 1 to 4.