JP2001055474A - Ethylene/alpha-olefin copolymer resin composition and expanded molded form - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject recyclable resin composition excellent in productivity and quality stability and suitable for producing the corresponding expanded molded form. SOLUTION: This resin composition comprises (A) an ethylene/α-olefin copolymer resin and (B) a crosslinked ethylene/α-olefin copolymer and satisfies the following (a) to (f) requirements: (a) gel fraction: 0.05-20 wt.%, (b) Mw/Mn of the component freed from the gel: <=3, (c) MFR: 0,5-5 g/10 min, (d) G's gradient S (S=ΔlogG'/Δlogf): 0.70<S<0.90, (e) density: 0.850-0.980 g/cm3, and (f) fluid activation energy ΔH: <=35 kJ/mol.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an ethylene / α-olefin copolymer resin composition suitable for foam molding and a foam molded article obtained by molding the same.

[0002]

2. Description of the Related Art Foams of polyethylene resin are widely used mainly for cushioning materials, cushioning materials, shock absorbing materials and the like. Most of them are formed by gas foam molding or cross-linked foam molding. Gas foam molding is a method of dissolving an inert gas in resin and extruding it.
Foaming occurs when the pressure is released at the extruder outlet. In this method, the use of the extruder has been limited due to the fact that the pressure control inside the extruder is important and the molding machine is expensive, and it is difficult to obtain a product having a smooth surface. On the other hand, cross-linking foam molding is a process in which a polyethylene resin is mixed with a pyrolytic foaming agent and a peroxide having a decomposition temperature lower than the decomposition temperature of the foaming agent, and the mixture is heated to generate radicals and crosslink. Then, the foaming agent is decomposed and foamed. In addition, instead of using a peroxide, a method of irradiating ionizing radiation to crosslink is also known. However, these crosslinked foams cannot be recycled because the entire system is three-dimensionally crosslinked, which is not preferable from the viewpoint of environmental protection.

Under these circumstances, (a) the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) measured by gel permeation chromatography (GPC) is 3 or less, and (b) the density is 0.850-0.980 g / cm
³ , (c) a melt flow rate (MFR) at 190 ° C. and a load of 2160 g is 0.5 to 5 g / 10 min, and (d)
The value of G ′ in the frequency range from the frequency (f _C ) where the values of the storage elastic modulus (G ′) and the loss elastic modulus (G ″) match, obtained from the frequency dependence of dynamic viscoelasticity, to f _C / 10 The slope S (S = ΔlogG ′ / Δlogf) is 0.70
(S <0.90, (e) an ethylene / α-olefin copolymer resin having a flow activation energy ΔH of 35 kJ / mol or less determined in the range of 160 to 220 ° C. is recyclable; Further, it has been found that the thermoplastic resin is suitable for foam molding (Japanese Patent Application Laid-Open No. 10-1100).
No. 55). However, as disclosed in JP-A-10-110055, in order to obtain a resin excellent in foam molding, it is necessary to add a radical generator to the entire resin, decompose the radical generator, and cause the radical generator to react. Was. However, it is difficult to cause the entire resin to react uniformly, which may cause problems in productivity and stability of quality.

[0004]

DISCLOSURE OF THE INVENTION The present invention relates to an ethylene / α-olefin copolymer resin composition which is recyclable, has excellent productivity and quality stability, and is suitable for producing a foam molded article. And an ethylene / α-olefin copolymer foamed article obtained by molding the same.

[0005]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above problems, and as a result, it has been found that an ethylene / α-olefin copolymer resin composition having a specific composition has excellent foam moldability. It has been found that the present invention has been completed. That is, the present invention relates to an ethylene / α-olefin copolymer resin (A), a crosslinked ethylene / α-olefin copolymer obtained by adding a peroxide to an ethylene / α-olefin copolymer and then heating the mixture. B) The present invention relates to an ethylene / α-olefin copolymer resin composition and a foamed molded product, which comprises (B) and satisfies the following conditions (a) to (f).

(A) The gel fraction is 0.05 to 20% by weight. (B) The weight-average molecular weight (Mw) and number-average molecular weight (Mw) of the component from which the gel component has been removed, measured by gel permeation chromatography (GPC). (C) a melt flow rate (MFR) at 190 ° C. under a load of 2160 g of 0.5 to 5 g / 10 min. (D) a storage elastic modulus obtained from the frequency dependence of dynamic viscoelasticity. (G ′) and the value of the loss elastic modulus (G ″) coincide with the slope S of G ′ (S = ΔlogG ′ / Δlogf) in the frequency domain from frequency (f _C ) to f _C / 10. 70 <S <0.90 (e) Density 0.850 to 0.980 g / cm ³ (f) Flow activation energy ΔH determined in the range of 160 to 220 ° C. 35 kJ / mol or less. The invention will be described in detail.

The ethylene / α-olefin copolymer resin (A) used in the resin composition of the present invention is a linear low-density polyethylene obtained by copolymerizing ethylene and an α-olefin having 3 to 12 carbon atoms. The density at 23 ° C. is 0.850 to 0.980 g / cm ³ , and the weight average molecular weight (Mw) and the number average molecular weight (M
n) is 3 or less (Mw / Mn) and JIS K72
10 According to Condition 4, the melt flow rate (MFR) measured at 190 ° C. under a load of 2160 g is 0.5 to 1
0 g / 10. By being in this range,
The obtained resin composition is a material suitable for foam molding. The molecular weight distribution (Mw / Mn) was 150
C ALC / GPC (Column: GMHNR- manufactured by Tosoh Corporation)
H (S), solvent: 1,2,4-trichlorobenzene), and Mw and Mn were measured by GPC method.
It can be evaluated by calculating w / Mn.

[0008] The method for producing the ethylene / α-olefin copolymer resin (A) is not particularly limited, and it may be produced using various catalysts such as a titanium catalyst, a vanadium catalyst, or a metallocene catalyst. Can be.

The crosslinked ethylene / α-olefin copolymer (B) used in the resin composition of the present invention comprises ethylene / α
-Obtained by heating after adding a peroxide to an olefin copolymer. The concentration of the peroxide was 0.2 × 10 4 per 100 g of the ethylene / α-olefin copolymer.
⁻³ to 10 × 10 ⁻³ mol, preferably 1 × 10 ⁻³ to 10
It is desirable to adjust so as to have × 10 ⁻³ mol of a peroxide bond, and the resulting resin composition is a material suitable for foam molding. Further, the cross-linking reaction is preferably carried out under no shearing, and the resin composition obtained thereby is a material suitable for foam molding. Further, it is preferable that the crosslinked ethylene / α-olefin copolymer is finely crushed by freeze pulverization, mechanical pulverization, or the like, and then blended, since the surface of a product obtained by foam molding is reduced.

The gel fraction (insoluble component amount) in the crosslinked ethylene / α-olefin copolymer (B) is 30% by weight.
The above is preferable, and the resin composition obtained thereby becomes a material suitable for foam molding.

The gel fraction was dissolved in 1,2,4-trichlorobenzene at 135 ° C. to prepare a 0.1% solution, which was filtered through a 0.45 micron Teflon filter. It can be evaluated by measuring the weight of the component that could not be obtained.

The ethylene / α-olefin copolymer resin composition of the present invention is characterized in that the gel fraction is 0.05 to 20% by weight. The resulting resin composition is a material suitable for foam molding. The measurement of the gel fraction is performed by the above method. This measurement can also be performed using a product after foam molding, and is characterized in that the gel fraction in the product is 0.05 to 20% by weight.

The ethylene / α-olefin copolymer resin composition of the present invention is characterized in that the molecular weight distribution (Mw / Mn) of the component from which the gel component has been removed is 3 or less. The resulting resin composition is a material suitable for foam molding. The component from which the gel component has been removed refers to a component filtered with a Teflon filter at the time of gel fraction measurement. In addition, this measurement can also be performed using the product after performing foam molding.

Further, the ethylene / α-olefin copolymer resin composition of the present invention has a melt flow rate (MFR) of 0.5 to 5 g / 190 ° C. under a load of 2160 g.
It is characterized by being 10 minutes. The resulting resin composition is a material suitable for foam molding. In addition, this measurement can also be performed using the product after performing foam molding.

The ethylene / α-olefin copolymer resin composition of the present invention has a storage elastic modulus (G ′) and a loss elastic modulus (G ″) obtained from the frequency dependence of dynamic viscoelasticity.
Of G ′ in the frequency domain from the frequency (f _C ) where the value of F ′ matches to f _C / 10 (S = ΔlogG ′ / △
logf) is 0.70 <S <0.90. The resulting resin composition is a material suitable for foam molding.

Furthermore, the ethylene / α-olefin copolymer resin composition of the present invention has a flow activation energy ΔH determined in a temperature range of 160 to 220 ° C. of 35 kJ / mo.
1 or less. The resulting resin composition is a material suitable for foam molding.

The ethylene / α-olefin copolymer resin composition of the present invention has a density at 23 ° C. of 0.85
0 to 0.980 g / cm ³ . The resin composition obtained thereby becomes a material suitable for foam molding, and the foam molded article obtained by foam molding the present resin composition has excellent flexibility.

Ethylene / α-olefin copolymer resin (A) and crosslinked ethylene / α-olefin copolymer (B)
The blend ratio of (A) / (B) is 99.99 by weight fraction.
It is preferably from 9 / 0.1 to 70/30, and the resin composition obtained thereby is a material suitable for foam molding.

The method for producing the ethylene / α-olefin copolymer resin composition of the present invention is optional, and the ethylene / α-olefin copolymer resin composition may be produced by an internal mixer or a roll mill kneader.
α-olefin copolymer resin (A), crosslinked ethylene / α
-Obtained by blending the olefin copolymer (B).

The ethylene / α-olefin copolymer resin composition of the present invention is subjected to foam molding after adding a foaming agent. The foaming agent used at this time is arbitrary, and may be an azo compound, a nitroso compound, Organic chemical blowing agents such as hydrazine compounds, semicarbazide compounds, azide compounds, triazole compounds, and isocyanate compounds; and inorganic chemical blowing agents such as bicarbonates, carbonates, nitrites, and hydrides. Alternatively, two or more kinds are used. The amount of the foaming agent to be added is preferably 1 to 30 parts by weight based on 100 parts by weight of (A) + (B) in total, whereby a good foamed molded article can be obtained.

In the ethylene / α-olefin copolymer resin composition of the present invention, if necessary, for example, calcium carbonate, mica, talc, silica, barium sulfate, calcium sulfate, kaolin, clay, pyroferrite, bentonite , Sericanite, zeolite, nepheline cinite, attapulgite, wollastonite, ferrite, calcium silicate, magnesium carbonate, dolomite, antimony trioxide, titanium oxide, iron oxide, molybdenum disulfide, graphite, gypsum, glass beads, glass powder, Inorganic fillers such as glass balloons, glass fibers, quartz and quartz glass, and organic and inorganic pigments may be blended. Also, a foaming accelerator, a foaming aid, a foaming inhibitor,
Crystal nucleating agent, clarifying agent, anti-blocking agent, release agent,
Antistatic agent, slip agent, anti-fog agent, lubricant, heat stabilizer,
If necessary, an ultraviolet stabilizer, a light stabilizer, a weather resistance stabilizer, a fungicide, a rust inhibitor, an ion trapping agent, a flame retardant, a flame retardant auxiliary, etc. may be added.

Further, other rubbers and thermoplastic resins may be blended in the ethylene / α-olefin copolymer resin composition of the present invention as long as the object of the present invention is not deviated. Examples of such rubber include natural rubber, acrylonitrile butadiene rubber, butadiene rubber, isoprene rubber, styrene butadiene rubber, silicone rubber, polynorbornene rubber, and chloroprene rubber. Further, as a thermoplastic resin, for example,
Ethylene / ethyl acrylate copolymer, polybutene,
Examples include acid-modified polyolefins, polypropylene resins, ethylene homopolymers, ethylene / vinyl acetate copolymers, polyamides, styrene-based thermoplastic elastomers, and polyolefin-based thermoplastic elastomers.

The method of foam molding the ethylene / α-olefin copolymer resin composition of the present invention is not particularly limited. After kneading the foaming agent, the foam is once molded into a sheet or rod, and then heated in a heating furnace. The method of foaming by heating is desirable.
Here, when forming into a sheet or rod shape, the temperature must be lower than the decomposition temperature of the used foaming agent. The heating furnace to be used is not limited, and a batch type, a continuous type, or a salt bath can be used.

The foamed article obtained by foaming the ethylene / α-olefin copolymer resin composition is used for flooring, wallpaper, automobile interiors, various cushioning materials, pipes, tubes, panels, and the like.

[0025]

EXAMPLES The present invention will be described below with reference to examples, but these are merely examples, and the present invention is not limited to these examples.

Various measurements in the examples and comparative examples are shown below.

Melt flow rate (MFR) According to JIS K7210 condition 4, 190 ° C., 21
It was measured under a load of 60 g.

Density: A sample was immersed in hot water at 100 ° C. for 1 hour, and then allowed to cool to room temperature. The density was measured using a density gradient tube maintained at 23 ° C. in accordance with JIS K6760.

-Measurement of Gel Fraction (Amount of Insoluble Component)-The foamed molded article was dissolved in 1,2,4-trichlorobenzene at 135 ° C. to prepare a 0.1% solution, and the solution was prepared with a pore size of 0.1%.
When filtered through a 45 micron Teflon filter, the weight of the component that could not be filtered was determined.

-Measurement of molecular weight distribution- An ethylene / α-olefin copolymer resin or a foam molded product from which a gel component has been removed is dissolved in 1,2,4-trichlorobenzene at 135 ° C., and gel permeation chromatography is performed. Graphy (Waters 150C AL)
C / GPC (column: GMHNR-H manufactured by Tosoh Corporation)
(S), solvent: 1,2,4-trichlorobenzene)), Mw and Mn were measured, and Mw / Mn was calculated.

-Measurement of Dynamic Viscoelasticity- Using a conical disk type dynamic viscoelasticity measuring device SR-2000 (manufactured by Rheometrics), 160, 190, 220
The shear storage modulus G ′ and the shear loss modulus G ″ in the frequency range of 0.001 to 100 Hz at each temperature of ° C. were determined. These were synthesized using 160 ° C. as the reference temperature according to the principle of time-temperature superposition. The activation energy of the flow was determined according to the Arrhenius equation from the shift factor in determining the composite curve.

-Appearance of foam molded article- The foam molded article was visually observed and evaluated as follows.

：: There is no unevenness in thickness, and foaming is uniform.

Δ: There is some unevenness in thickness, but it is almost uniformly foamed.

×: The thickness unevenness is large and the foam is unevenly foamed.

~ Shape of foam molded body cell ~ The foam molded body is cut, and the cut surface is visually observed.
The evaluation was as follows.

：: The cells are uniform.

Δ: Cells are somewhat non-uniform.

×: The cells are non-uniform.

-Measurement of expansion ratio- Specific gravity (SA) before foam molding and specific gravity (S) after foam molding
B) Substitute hydrometer (trade name ARCHIMIDE)
S, manufactured by NADA Electronics), and (SA) / (SB) was defined as the expansion ratio.

Example 1 Ethylene / 1-hexene copolymer (EXACT4051, trade name: EXACT4051, MFR: 2.3 g / 10)
Min, density: 0.900 g / cm ³ , Mw / Mn: 1.
9) was kneaded by a roll mill kneader having a surface temperature of 150 ° C., and α, α′-bis (t-butylperoxy-m-isopropyl) benzene (trade name: Perbutyl, manufactured by NOF CORPORATION) as a peroxide P) was added at 0.25 wt%. Thereby, the number of moles of the peroxide bond is 1.5 × 10 ⁻³ per 100 g of the ethylene / 1-hexene copolymer.
mol. The obtained kneaded product was cross-linked by heating for 15 minutes with a compression molding machine set at 190 ° C. to obtain a cross-linked ethylene / 1-hexene copolymer, which was freeze-pulverized.

30 g of a pulverized product of a crosslinked ethylene / 1-hexene copolymer, an ethylene / 1-hexene copolymer (EXX
ONACT, trade name EXACT4024, MFR: 3.
9 g / 10 min, density: 0.890 g / cm ³ , Mw / M
n: 1.9) 470 g, hindered phenol-based heat stabilizer (manufactured by Ciba-Geigy, trade name: Irganox 10)
10) 3 g of a phosphorus-based heat stabilizer (trade name: Irgafos 168, manufactured by Ciba Geigy) was kneaded for 15 minutes by a roll mill kneader having a surface temperature of 100 ° C. Further, 50 g of p, p'-oxybisbenzenesulfonylhydrazine (manufactured by Sankyo Kasei Co., Ltd., product name: CellMike s) was added as a foaming agent and kneaded for 3 minutes to obtain a target resin composition. After compression molding this roll sheet at 100 ° C,
Foam molding was performed in an oven that had been heated in advance. The oven heater temperature was 190 ° C. and the time was 4 minutes. After taking out from the oven, the gel fraction, molecular weight distribution, MFR, and expansion ratio of the foamed molded article were measured, and further, the appearance of the foamed molded article and the shape of the cell were examined.

Comparative Example 1 In Example 1, various measurements and moldings were carried out without adding the crosslinked ethylene / 1-hexene copolymer.

Comparative Example 2 Low-density polyethylene produced by a high-pressure radical method instead of the crosslinked ethylene / 1-hexene copolymer (trade name Petrocene # 360, manufactured by Tosoh Corporation, MFR:
A composition was obtained in the same manner as in Example 1 except that 1.6 g / 10 min, Mw / Mn: 9.4), and various measurements and molding were performed.

Comparative Example 3 Ethylene / 1-octene copolymer having a long-chain branch introduced into the main chain thereof (manufactured by Dow, trade name Engage EG81)
00, MFR: 1.0 g / 10 min, density: 0.870 g
/ Cm ³ , Mw / Mn: 2.0).

Comparative Example 4 Low-density polyethylene produced by a high-pressure radical method (trade name: Petrocene # 360, manufactured by Tosoh Corporation)
FR: 1.6 g / 10 min, Density: 0.920, Mw /
Various measurements and molding were performed using Mn: 9.4).

Comparative Example 5 Peroxide α, α'-bis (t-butylperoxy-m-
Isopropyl) benzene (trade name, manufactured by NOF Corporation)
Perbutyl P) was added to 0.089 wt%, and the number of moles of peroxide bonds was changed to ethylene / 1-hexene copolymer 10
5.3 × 10 ^-4 mol per 0 g, and an ethylene / 1-hexene copolymer (trade name, manufactured by EXXON)
(EXACT4024) instead of ethylene / 1-octene copolymer (EXACT30, trade name, EXACT30)
28, MFR: 1.1 g / 10 minutes, density: 0.890 g
/ Cm ³ , Mw / Mn: 1.8) except that the composition was obtained in the same manner as in Example 1, and various measurements and molding were carried out.

[0048]

[Table 1]

[0049]

[Table 2]

[0050]

The ethylene / α-olefin copolymer resin composition obtained by the present invention has excellent foam moldability.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F074 AA17 AA17N AB02 BA06 BA08 BA13 BA14 BA15 BA17 BA18 BA19 BB02 CA29 CC04Y CC06X CC22X DA33 DA35 DA52 DA58 4J002 BB151 BB152 EQ016 EQ026 EQ036 ER016 EU176 FD010 FD326

Claims (2)

[Claims] 1. A crosslinked ethylene / α-olefin copolymer (B) obtained by heating after adding a peroxide to an ethylene / α-olefin copolymer resin (A) or an ethylene / α-olefin copolymer (B). ), And the following (a) to (f)
An ethylene / α-olefin copolymer resin composition satisfying the following conditions: (A) The gel fraction is 0.05 to 20% by weight. (B) The weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the component from which the gel component has been removed, measured by gel permeation chromatography (GPC). (C) Melt flow rate (MFR) at 190 ° C. under a load of 2160 g of 0.5 to 5 g / 10 min. (D) Storage elastic modulus (G ′) obtained from frequency dependence of dynamic viscoelasticity ) And loss elastic modulus (G ″) have a slope S (S = ΔlogG ′ / Δlogf) of 0.70 <S in the frequency range from frequency (f _C ) to f _C / 10. <0.90 (e) Density 0.850 to 0.980 g / cm ³ (f) Flow activation energy ΔH determined in the range of 160 to 220 ° C. 35 kJ / mol or less 2. A foam molded article obtained by molding the ethylene / α-olefin copolymer resin composition according to claim 1.