JP7729142B2 - thermoplastic resin composition - Google Patents

Description

The present invention relates to a thermoplastic resin composition.

Thermoplastic resin compositions, particularly polyolefin resins, are inexpensive and have excellent moldability, rigidity, and electrical insulation properties, making them widely used in films, fibers, and other molded products of various shapes. Furthermore, various modifiers for polyolefin resins have been developed, and modifiers containing low-molecular-weight polyolefins have been proposed to improve pigment dispersibility and mechanical strength (see, for example, Patent Document 1).

JP 2015-117362 A

However, even with the above technology, mechanical strength was not fully satisfactory. The object of the present invention is to provide a thermoplastic resin composition with excellent mechanical strength.

The present inventors have conducted extensive research to achieve the above object and have arrived at the present invention, which relates to a thermoplastic resin composition (X) comprising the following polyolefin resin (A) and the following polyolefin resin (D), in which the weight ratio of the polyolefin resin (A) to the polyolefin resin (D) [(A)/(D)] is 0.01/99.99 to 0.9/99.1.
Polyolefin resin (A): Contains an α-olefin (having 3 to 8 carbon atoms) as a constituent monomer, and the isotacticity of the α-olefin portion is 1 to 69%;
Polyolefin resin (D): Contains an α-olefin (having 3 to 8 carbon atoms) as a constituent monomer, and the isotacticity of the α-olefin portion is 70 to 100%;

The thermoplastic resin composition (X) of the present invention has the following effects.
(1) It gives molded products excellent mechanical strength (tensile strength, impact strength).
(2) Even if the polyolefin resin (D) is a recycled polyolefin resin (DR), the polyolefin resin (D) has excellent mechanical strength.

<Polyolefin resin (A)>
The polyolefin resin (A) in the present invention contains an α-olefin (having 3 to 8 carbon atoms) as a constituent monomer, and the isotacticity of the α-olefin portion is 1 to 69%.

In the following, "α-olefin (having 3 to 8 carbon atoms)" may be referred to as "α-olefin".
Examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and 1-octene.
Of the above α-olefins, propylene is preferred from the viewpoint of isotacticity, which will be described later.

The polyolefin resin (A) may contain other monomers in addition to the α-olefin as constituent monomers. In such cases, the weight of the other monomers is preferably 20% by weight or less, more preferably 10% by weight or less, and even more preferably 2% by weight or less, based on the weight of all monomers constituting the polyolefin resin (A).

Examples of other monomers constituting the polyolefin resin (A) include ethylene, 2-butene, isobutene, α-olefins having 9 to 30 carbon atoms (hereinafter sometimes abbreviated as C) (1-decene, 1-dodecene, etc.), and C4 to C30 unsaturated monomers other than α-olefins (for example, vinyl acetate).
Of the above other monomers, ethylene is preferred. Among (A), propylene/ethylene copolymers and propylene polymers are preferred, and propylene polymers are more preferred.

From the viewpoint of mechanical strength, the isotacticity of the α-olefin portion of polyolefin resin (A) is preferably 1 to 69%, more preferably 10 to 65%, and particularly preferably 30 to 60%.

The isotacticity in the present invention can be calculated using ¹³ C-NMR (nuclear magnetic resonance spectroscopy). Generally, when the α-olefin is propylene, a side-chain methyl group, or when the α-olefin is 1-butene, 1-pentene, 1-hexene, 1-heptene, or 1-octene, a side-chain methylene group adjacent to a main-chain methine group is affected by the configuration (meso or racemo) of both adjacent groups (triad), both adjacent groups of the triad (pentad), and even both adjacent groups of the pentad (heptad), and is known to result in peaks being observed at different chemical shifts. For this reason, stereoregularity is generally evaluated for the pentad, and the isotacticity in the present invention is also calculated based on the evaluation of the pentad.

That is, when the α-olefin is propylene, the carbon peak derived from the side chain methyl group in propylene obtained by ^C -NMR, and when the α-olefin is 1-butene, 1-pentene, 1-hexene, 1-heptene, or 1-octene, the carbon peak derived from the side chain methylene group adjacent to the main chain methine group in the α-olefin obtained by ^C -NMR, respectively, the intensity of each pentad peak in the α-olefin portion of polyolefin (A) is (H); when the α-olefin in an isotactic polyolefin having a pentad formed only of a mesostructure is propylene, the peak intensity derived from the methyl group in the α-olefin is propylene; and when the α-olefin is 1-butene, 1-pentene, 1-hexene, 1-heptene, or 1-octene, the peak intensity derived from the side chain methylene group adjacent to the main chain methine group in the α-olefin obtained by ^C -NMR is (Ha); isotacticity is calculated by the following formula:

Isotacticity (%) = [(Ha) / Σ(H)] × 100 (1)

The conditions for measuring isotacticity in the present invention are as follows.
・Device: JEOL Ltd. ECZ400R
Measurement mode: Proton decoupling method Pulse width: 8 μsec
Pulse repetition time: 4.6 seconds
Relaxation time: 3.0 seconds
・Number of measurements: 10,000 ・Solvent: orthodichlorobenzene ・Reference material: tetramethylsilane ・Sample concentration: 10 mg/mL
・Measurement temperature: 120℃

From the viewpoint of mechanical strength, the number average molecular weight (Mn) of the polyolefin resin (A) is preferably 1,000 to 100,000, more preferably 10,000 to 80,000, and particularly preferably 20,000 to 60,000.

In the present invention, the number average molecular weight (Mn) and weight average molecular weight (Mw) can be measured by GPC (gel permeation chromatography).
In the present invention, the conditions for measuring Mn by GPC are as follows.
・Apparatus: High-temperature gel permeation chromatography
["Alliance GPCV2000", manufactured by Waters Corporation]
Detector: Refractive index detector Solvent: Orthodichlorobenzene Reference material: Polystyrene Sample concentration: 3 mg/ml
・Column stationary phase: PLgel 10 μm, MIXED-B 2 columns in series
[Manufactured by Polymer Laboratories, Inc.]
Column temperature: 135°C
・Reference material: Standard polystyrene

The polyolefin resin (A) can be produced by known methods, but it may also be a commercially available product. Examples of commercially available products include those sold under the trade names "ELMODU S400," "ELMODU S410," "ELMODU S600," and "ELMODU S901," all manufactured by Idemitsu Kosan Co., Ltd.

<Polyolefin resin (D)>
The polyolefin resin (D) in the present invention contains an α-olefin (having 3 to 8 carbon atoms) as a constituent monomer, and the isotacticity of the α-olefin portion is 70 to 100%.

Examples of the α-olefin include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, and 1-octene.
Of the above α-olefins, propylene is preferred from the viewpoint of mechanical strength.

The polyolefin resin (D) may contain other monomers in addition to the α-olefin as constituent monomers. In such cases, the weight of the other monomers is preferably 20% by weight or less, more preferably 10% by weight or less, and even more preferably 2% by weight or less, based on the weight of all monomers constituting the polyolefin resin (D).

Examples of other monomers constituting the polyolefin resin (D) include ethylene, 2-butene, isobutene, α-olefins having 9 to 30 carbon atoms (hereinafter sometimes abbreviated as C) (1-decene, 1-dodecene, etc.), and C4 to C30 unsaturated monomers other than α-olefins (for example, vinyl acetate).
Of the above other monomers, ethylene is preferred, and among (D), propylene/ethylene copolymers and propylene polymers are preferred, with propylene polymers being more preferred.

From the viewpoint of mechanical strength, the isotacticity of the α-olefin portion of polyolefin resin (D) is preferably 70 to 100%, more preferably 75 to 100%, and particularly preferably 80 to 100%.

From the viewpoint of mechanical strength, the number average molecular weight (Mn) of the polyolefin resin (D) is preferably 20,000 to 400,000, and more preferably 40,000 to 300,000.

Recycled polyolefin resin (DR) is also suitable as polyolefin resin (D). (DR) is preferably a polyolefin resin that has been molded once and then crushed, pulverized, pelletized, or otherwise processed.

<Thermoplastic resin composition (X)>
The thermoplastic resin composition (X) of the present invention contains the polyolefin resin (A) and the polyolefin resin (D), and the weight ratio of the polyolefin resin (A) to the polyolefin resin (D) [(A)/(D)] is 0.01/99.99 to 0.9/99.1.
If the weight ratio [(A)/(D)] is less than 0.01/99.99, the Izod impact strength of the molded article will be poor, and if it exceeds 0.9/99.1, the mechanical strength of the molded article will be poor.
The weight ratio [(A)/(D)] is preferably 0.05/99.95 to 0.8/99.2, and more preferably 0.1/99.1 to 0.5/99.5.

The thermoplastic resin composition (X) of the present invention may further contain, if necessary, one or more additives (N) selected from the group consisting of fillers (N1), colorants (N2), matting agents (N3), antistatic agents (N4), dispersants (N5), flame retardants (N6), foaming agents (N7), antioxidants (N8), ultraviolet absorbers (N9), and plasticizers (N10), within the scope of the present invention, provided that the effects of the present invention are not impaired.

Examples of the filler (N1) include organic fillers (for example, wood flour, cellulose) and inorganic fillers (for example, calcium carbonate, talc, glass fiber, carbon fiber).
Among these fillers (N1), from the viewpoint of mechanical strength, inorganic fillers are preferred, and calcium carbonate is more preferred. The amount of (N1) used based on the total weight of the thermoplastic resin composition (X) is, for example, 70% by weight or less, preferably 3 to 70% by weight, and more preferably 5 to 40% by weight.

The total amount of (N2) to (N10) used in the thermoplastic resin composition (X) of the present invention is, for example, 30% by weight or less, based on the total weight of the thermoplastic resin composition (X), and preferably 1 to 20% by weight from the viewpoint of functional expression of (N) and industrial considerations.

The amount of each additive (N) other than (N1) used, based on the total weight of the thermoplastic resin composition (X), is as follows: (N2) is, for example, 10% by weight or less, preferably 1 to 5% by weight; (N3) is, for example, 20% by weight or less, preferably 1 to 10% by weight; (N4) is, for example, 10% by weight or less, preferably 1 to 5% by weight; (N5) is, for example, 20% by weight or less, preferably 0 to 15% by weight, more preferably 0 to 10% by weight; (N6) is, for example, 15% by weight or less, preferably 3 to 10% by weight; (N7) is, for example, 1 to 20% by weight or less, preferably 5 to 15% by weight; (N8) is, for example, 3% by weight or less, preferably 0.01 to 1% by weight; (N9) is, for example, 3% by weight or less, preferably 0.01 to 1% by weight; and (N10) is, for example, 20% by weight or less, preferably 5 to 15% by weight.

In addition, when the same additives are used in (N1) to (N10), the amount of each additive that achieves its corresponding additive effect should not be used regardless of the effects of the other additives, but rather the amount used should be adjusted according to the intended use, taking into consideration that the effects of the other additives can also be obtained at the same time.

The method for producing the thermoplastic resin composition (X) of the present invention includes the following steps:
(1) A method in which the entire amounts of the polyolefin resin (D) and the polyolefin resin (A), and optionally (N), are mixed together in one lump to prepare a resin composition (lump method);
(2) A method (masterbatch method) in which a part of the polyolefin resin (D), the whole amount of the polyolefin resin (A), and, if necessary, a part or all of the additive (N) are mixed to prepare a masterbatch resin composition containing a high concentration of the polyolefin resin (A), and then the remaining polyolefin resin (D) and, if necessary, the remaining additive (N) are added and mixed to prepare a resin composition.
From the viewpoint of the mixing efficiency of the polyolefin resin (A), the method (2) is preferred.

<Molded product>
The molded article of the present invention is a molded product of the thermoplastic resin composition (X). That is, the molded article of the present invention is obtained by molding the thermoplastic resin composition (X).
Examples of molding methods include injection molding, compression molding, calendar molding, slush molding, rotational molding, extrusion molding, blow molding, and film molding (casting, tenter molding, inflation molding, etc.), and molding can be performed by any method incorporating means such as single-layer molding, multi-layer molding, or foam molding depending on the purpose. Examples of the form of the molded product include plate-like, sheet-like, film-like, fiber-like (including nonwoven fabric, etc.), etc.

Examples of the present invention will be described below, but the present invention is not limited to these. In the following, parts indicate parts by weight. In the following, Examples 1 to 3 and 11 to 13 correspond to Reference Examples 1 to 6, respectively.

<Examples 1 to 3, Comparative Examples 1 and 2>
According to the blending composition (parts) in Table 1, polyolefin resin (A) and polyolefin resin (D) were melt-kneaded in a twin-screw extruder [trade name "KZW45TW", manufactured by Technovel Co., Ltd.] at 230°C and 100 rpm to obtain each thermoplastic resin composition (X).
Each thermoplastic resin composition (X) was injection molded using an injection molding machine (trade name "PS40E5ASE", manufactured by Nissei Plastics Co., Ltd.) at a nozzle temperature of 230°C and a mold temperature of 50°C, and evaluated according to the evaluation methods described below. The results are shown in Table 1.

<Evaluation method>
(1) Tensile Strength Tensile strength was measured in accordance with JIS K7171 and evaluated.
<Evaluation criteria>
◎: 30 MPa or more ○: 25 MPa or more and less than 30 MPa △: 20 MPa or more and less than 25 MPa ×: Less than 20 MPa

(2) Impact Resistance The Izod impact value was measured in accordance with JIS K7110.
<Evaluation criteria>
◎: 3.0 kJ/ ^m2 or more ○: 1.5 kJ/ ^m2 or more and less than 3.0 kJ/ ^m2 △: 1.0 kJ/ ^m2 or more and less than 1.5 kJ/ ^m2 ×: Less than 1.0 kJ/ ^m2

<Examples 11 to 13, Comparative Examples 11 and 12>
According to the blending composition (parts) in Table 2, the polyolefin resin (A) and the recycled polyolefin resin (DR) were melt-kneaded in a twin-screw extruder [trade name "KZW45TW", manufactured by Technovel Co., Ltd.] at 230°C and 100 rpm to obtain each thermoplastic resin composition (X).
After pelletizing, the mixture was injection molded using an injection molding machine (trade name "PS40E5ASE", manufactured by Nissei Plastics Co., Ltd.) at a nozzle temperature of 230°C and a mold temperature of 50°C to prepare test specimens, which were evaluated according to the evaluation methods described below. The results are shown in Table 2.

(1) Tensile Strength Tensile strength was measured in accordance with JIS K7171 and evaluated.
<Evaluation criteria>
◎: 25 MPa or more ○: 20 MPa or more and less than 25 MPa △: 15 MPa or more and less than 20 MPa ×: Less than 15 MPa

(2) Impact Resistance The Izod impact value was measured in accordance with JIS K7110.
<Evaluation criteria>
◎: 2.5 kJ/m2 or ^more ○: 1.2 kJ/ ^m2 or more and less than 2.5 kJ/ ^m2 △: 0.8 kJ/ ^m2 or more and less than 1.2 kJ/ ^m2 ×: Less than 0.8 kJ/ ^m2

<Examples 21 to 23, Comparative Examples 21 to 22>
According to the blending composition (parts) in Table 3, polyolefin resin (A), polyolefin resin (D), and filler (N1) were melt-kneaded in a twin-screw extruder [trade name "KZW45TW", manufactured by Technovel Co., Ltd.] at 230°C and 100 rpm to obtain each thermoplastic resin composition (X).
After pelletizing, the mixture was injection molded using an injection molding machine (trade name "PS40E5ASE", manufactured by Nissei Plastics Co., Ltd.) at a nozzle temperature of 230°C and a mold temperature of 50°C to prepare test specimens, which were evaluated according to the evaluation methods described below. The results are shown in Table 3.

(1) Tensile Strength Tensile strength was measured in accordance with JIS K7171 and evaluated.
<Evaluation criteria>
◎: 25 MPa or more ○: 20 MPa or more and less than 25 MPa △: 15 MPa or more and less than 20 MPa ×: Less than 15 MPa

(2) Impact Resistance The Izod impact value was measured in accordance with JIS K7110.
<Evaluation criteria>
◎: 2.5 kJ/m2 or ^more ○: 1.2 kJ/ ^m2 or more and less than 2.5 kJ/ ^m2 △: 0.8 kJ/ ^m2 or more and less than 1.2 kJ/ ^m2 ×: Less than 0.8 kJ/ ^m2

The results in Tables 1 to 3 show that the thermoplastic resin composition (X) of the present invention provides molded articles with superior mechanical strength compared to the comparative compositions. Furthermore, even when the polyolefin resin (D) is a recycled polyolefin resin (DR), it still provides superior mechanical strength.

Each thermoplastic resin composition (X) of the present invention imparts excellent mechanical strength to molded articles. Therefore, it is suitable as a material for housing products (for home appliances, office equipment, game machines, office equipment, etc.) molded by various molding methods [such as injection molding, compression molding, calendar molding, slush molding, rotational molding, extrusion molding, blow molding, foam molding, and film molding (casting, tenter molding, and inflation molding)], plastic container materials [such as trays (IC trays, etc.) and other containers used in clean rooms], various cushioning materials, covering materials (such as packaging films and protective films), flooring sheets, artificial turf, mats, tape substrates (for semiconductor manufacturing processes, etc.), and various molded articles (such as automobile parts).

Claims (3)

A thermoplastic resin composition (X) comprising the following polyolefin resin (A), the following polyolefin resin (D), and a filler (N1), wherein the filler (N1) is calcium carbonate, the number average molecular weight (Mn) of the polyolefin resin (D) is 20,000 to 400,000, the weight ratio of the polyolefin resin (A) to the polyolefin resin (D) [(A)/(D)] is 0.01/99.99 to 0.9/99.1, and the weight of the filler (N1) is 5 to 40% by weight based on the weight of the thermoplastic resin composition (X).
Polyolefin resin (A): a propylene/ethylene copolymer or propylene polymer containing an α-olefin (having 3 carbon atoms) as a constituent monomer, the α-olefin portion having an isotacticity of 30 to 65%;
Polyolefin resin (D): a propylene/ethylene copolymer or propylene polymer containing an α-olefin (having 3 carbon atoms) as a constituent monomer, in which the isotacticity of the α-olefin portion is 70 to 100%; The thermoplastic resin composition (X) according to claim 1, wherein the polyolefin resin (A) has a number average molecular weight (Mn) of 1,000 to 100,000. A molded article obtained by molding the thermoplastic resin composition (X) described in claim 1 or 2.