JP5294129B2 - Metallocene-ethylenepropylene diene copolymer rubber-based open cell body and method for producing the same - Google Patents

Description

  The present invention relates to a metallocene-ethylenepropylenediene copolymer rubber-based open cell body and a method for producing the same.

As is well known, an ethylene propylene diene copolymer rubber (hereinafter also referred to as “EPDM”) type open cell product is used as a cushioning material, heat insulating material, sound absorbing material, etc. due to its excellent cushioning properties, sealing properties, and soundproofing properties. It is used for home appliances, automobiles, buildings, and other applications. In addition, polyethylene-based open cells are excellent in heat insulation, sound absorption, and chemical resistance, so they are widely used in various applications such as heat insulation materials in air conditioners, sound absorption materials in automobile door mirrors, bacteria carriers, and coating materials. It's being used.
Further, a foamed composition obtained by adding 4,4′-oxybis (benzenesulfonylhydrazide) to a polyethylene resin obtained using a metallocene compound as a polymerization catalyst is shaped, and then foamed by heating and foaming under normal pressure. A process for producing a metallocene polyethylene open-celled body is proposed in which the foam is subjected to mechanical deformation to make the bubbles communicate with each other (see Japanese Patent Application Laid-Open No. 2001-226511).
However, the above-mentioned EPDM-based open cell body is prone to surface bloom (precipitation phenomenon), has poor oil resistance and bending crack resistance, uses an organic peroxide as a cross-linking agent, and a 2-mercaptobenzimidazole-based scorch inhibitor. In the case of EPDM foams using the above, there is a problem that it is difficult to adjust the cross-linking, and the closed cells are difficult to become open cells. Further, the polyethylene-based open cell body has a problem that it is inferior in flexibility, elasticity, and recoverability at the time of compression compared to the EPDM open-cell body.
In addition, the metallocene polyethylene open-cell body has a problem that it is necessary to use 4,4′-oxybis (benzenesulfonylhydrazide) as a foaming agent, and a foam having a thickness cannot be obtained.
Therefore, the present invention is to foam a composition comprising a metallocene polyethylene resin suitable for crosslinking with an organic peroxide and an ethylene propylene diene copolymer rubber excellent in flexibility and recoverability as an essential component. A continuous structure that balances crosslinking and foaming, and overcomes the problems of open-cell bodies that each of the metallocene polyethylene resin and the ethylene propylene diene copolymer rubber has independently. The remarkable knowledge that a foam can be obtained has been obtained, and the technical problem has been achieved.

The metallocene-ethylenepropylene diene copolymer rubber open-cell body according to the present invention is composed of 100 parts by weight of a composition comprising 30 to 70 parts by weight of a metallocene polyethylene resin and 70 to 30 parts by weight of ethylene propylene diene copolymer rubber. On the other hand, a composition containing 0 to 40 parts by weight of a polyethylene resin (excluding a metallocene polyethylene resin) and / or vinyl acetate resin and 20 to 150 parts by weight of a filler is heated and foamed to form closed cells, which are then independent. It is a metallocene-ethylenepropylene diene copolymer rubber-based open cell having an apparent density of 84 to 89 kg / m ³ formed by forming open cells in which bubbles are connected .
The metallocene-ethylenepropylene diene copolymer rubber-based open cell manufacturing method according to the present invention comprises a composition comprising 30 to 70 parts by weight of a metallocene polyethylene resin and 70 to 30 parts by weight of an ethylene propylene diene copolymer rubber. Organic peroxide and foaming agent in a composition in which 0 to 40 parts by weight of polyethylene resin (excluding metallocene polyethylene resin) and / or vinyl acetate resin and 20 to 150 parts by weight of filler are blended with 100 parts by weight of the product , Adding foaming aids, softeners and fillers, then filling the mold during pressing, heating under pressure, and further foaming at normal pressure and then making the bubbles continuous .
According to the present invention, the composition in which the metallocene-based polyethylene resin and the ethylene propylene diene copolymer rubber are mixed is an essential component, and the mixture obtained by adding a filler to the composition is foamed. Can be obtained, and an open cell body excellent in flexibility and recoverability without scorch can be obtained.

Embodiment 1 FIG.
The metallocene-EPDM open-cell body according to the present embodiment has a composition composed of 30 to 70 parts by weight of a metallocene polyethylene resin and 70 to 30 parts by weight of EPDM as an essential component, and an organic peroxide or foam is added to the composition. A mixture obtained by adding an agent, a foaming aid, a softening agent and a filler is heated and foamed, and the generated bubbles are made continuous.
The blending ratio of the metallocene polyethylene resin and EPDM is preferably 70 to 30 parts by weight of EPDM with respect to 30 to 70 parts by weight of the metallocene polyethylene resin, more preferably 40 to 60 parts by weight of the metallocene polyethylene resin. EPDM is 60 to 40 parts by weight.
The metallocene polyethylene resin is a polyethylene resin obtained using a metallocene compound as a polymerization catalyst.
The EPDM includes ethylidene norbornene, 1,4-hexadiene, dichloropentadiene and the like as the third component, but is not particularly limited.
Furthermore, 0 to 40 parts by weight of at least one selected from ordinary polyethylene resin (LDPE) and vinyl acetate resin (EVA) may be blended with 100 parts by weight of the essential component composition. If the amount is 40 parts by weight or less, the flexibility and recoverability of the foam is excellent, and if it exceeds 40 parts by weight, the flexibility and recoverability of the foam will be adversely affected.
The organic peroxide is decomposed by heating to generate an organic radical as a radical generator that generates free radicals and generates crosslinks between or within the molecules. For example, dicumyl peroxide, 1,1-ditertiary butyl peroxide, 1,1-ditertiary butyl peroxy-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-ditertiary butyl peroxide Oxyhexane, 2,5-dimethyl-2,5-ditertiary butyl peroxyhexine, α, α-ditertiary butyl peroxyisopropylbenzene, tertiary butyl peroxyketone, tertiary butyl peroxybenzoate, etc. Can be used.
Examples of the foaming agent include azo compounds such as azodicarbonamide and barium azodicarboxylate, nitroso compounds such as dinitrosopentamethylenetetramine and trinitrotrimethyltriamine, and p, p′-oxybisbenzenesulfonyl hydragit. Etc., and sulfonyl semicarbadidate compounds such as p, p′-oxybisbenzenesulfonyl semicarbadiate and trienesulfonyl semicarbadi may be used.
As the foaming aid, a compound containing urea as a main component, a metal oxide such as zinc oxide or lead oxide, a compound containing salicylic acid or stearic acid as a main component, that is, a higher fatty acid or a higher fatty acid metal compound is used. What is necessary is just to add the said foaming adjuvant according to the kind of foaming agent.
As the softening agent, those having good compatibility with rubber such as process oil, plasticizer, paraffin wax, and fluid paraffin may be used.
As the filler, clay, talc, titanium oxide, aluminum hydroxide, magnesium hydroxide, calcium carbonate, silica, and other conventional rubber compounding agents may be used. What is necessary is just to add the said filler as needed, and it is preferable that the addition amount of a filler shall be 20-150 weight part with respect to 100 weight part of compositions which consist of a metallocene polyethylene resin and EPDM. When the added amount of the filler exceeds 150 parts by weight, the foam molding is hindered and a satisfactory foam cannot be obtained. This is not preferable, and the added amount of less than 20 parts by weight is too small to meet the cost. Since it is not, it is not preferable. More preferably, it is 30-80 weight part.
Embodiment 2. FIG.
The method for producing a metallocene-EPDM open cell body according to the present embodiment includes an organic peroxide in a composition comprising 30 to 70 parts by weight of a metallocene polyethylene resin and 70 to 30 parts by weight of ethylene propylene diene copolymer rubber. , Adding a foaming agent, a foaming aid, a softening agent and a filler to make a mixture, then filling the mixture in a mold in a press and heating under pressure, and further foaming at normal pressure After that, the bubbles are mechanically continuous.
The production method can be carried out under a known foaming method and appropriate foaming conditions depending on the foaming temperature, crosslinking initiation temperature, etc. of the organic peroxide and foaming agent used, and a particularly suitable production method is specifically described. explain.
A composition comprising 30 to 70 parts by weight of a metallocene polyethylene resin and 70 to 30 parts by weight of an ethylene propylene diene copolymer rubber, and 30 to 80 parts by weight of a filler, in addition, a polyethylene resin, a vinyl acetate resin, an organic peroxide, A softener, a foaming agent, and a foaming aid are added to form a blend, and the blend is kneaded by a mixing roll, a pressure kneader, an extruder, or the like. Next, the obtained foamable resin composition is filled in a mold during pressing, heated at 115 to 150 ° C. under pressure for a certain period of time, partially decomposes the foaming agent, and has an expansion ratio of 1.00 to 1.05. An intermediate foam is produced. Next, the intermediate foam is put in a mold having a desired shape such as a rectangular parallelepiped mold which is not a closed system under normal pressure, and heated at 140 to 180 ° C. to completely decompose the organic peroxide and the foaming agent, thereby obtaining a foam. Get.
Then, the foam (closed cell) is compressed and deformed by, for example, a constant-velocity two-roll to break the bubble film, thereby mechanically connecting the bubbles to obtain an open cell. An infinite number of small needles are provided on the surface of the constant-velocity two-roll, or a roll provided with innumerable small needles is arranged before and / or after the constant-speed two-roll, and the surface of the closed cell body is innumerable. If the small holes are opened, the communication of bubbles can be promoted.

Examples 1-13, Comparative Examples 1-9
Affinity EG8150 (trade name: density: 0.868 g / cm ³ , MFR: 0.5 g / 10 min, manufactured by Dow Chemical Japan Co., Ltd.) and affinity EG8200 (trade name: density: 0.870 g / cm) as metallocene polyethylene resins ³ , MFR: 5.0 g / 10 min: manufactured by Dow Chemical Japan Co., Ltd., and Esprene 514F (trade name: Mooney viscosity: 35 ML (1 + 4) 100 ° C., ethylene content: 70%, diene content: 5. 5%, manufactured by Sumitomo Chemical Co., Ltd.) was obtained at a blending ratio shown in Table 1 (Example) and Table 2 (Comparative Example), and YF-30 (trade name) was used as the polyethylene resin in each composition. : low density polyethylene, ^{density: 0.920g / cm 3, MFR:} 1.1g / 10 minutes, manufactured by Japan polyethylene Corporation), acetic bi LV540 as Le resin (trade name: ethylene - vinyl acetate copolymer, ^{density: 0.942g / cm 3, MFR:} 2.5g / 10 min: manufactured by Japan Polyethylene Corporation), dicumyl peroxide as the organic peroxide , Process oil as a softening agent, talc as a filler, azodicarbonamide as a foaming agent, and zinc oxide as a foaming aid are added at the blending ratios shown in Tables 1 and 2 to obtain respective blends. Was filled in a mold (32 × 160 × 160 mm) in a press heated to 130 ° C., and heated at a pressure of 100 kg / cm ² for 80 minutes to produce each intermediate foam (32 × 160 × 160 mm).
Next, the intermediate foam was placed in the approximate center of a non-airtight mold (90 × 300 × 300 mm), and was taken out by heating at 160 ° C. for 180 minutes to obtain each foam (90 × 300 × 300 mm) ( Examples 1 to 13, Comparative Examples 2, 3, 5 to 8).
Each foam obtained was passed 5 times between two constant-velocity rolls set at a roll interval of 20 mm to break the bubble film, and the bubbles were connected to each open cell (Examples 1 to 13, comparison). Examples 2, 3, 5-8) were obtained.
Table 3 (Example) and Table 4 (Comparative Example) show the apparent density, compressive stress, and compression set of each open cell body obtained.
According to Table 3 and Table 4, it has confirmed that the open-cell body of Examples 1-13 was excellent in a softness | flexibility, elasticity, and recoverability. In Comparative Examples 1, 4 and 9, the scorch was so bad that a satisfactory foam could not be obtained. In Comparative Examples 2, 3, 5 to 8, foams were obtained, but the flexibility and recoverability were poor. The apparent density, tensile strength, elongation, compression stress and compression set of the foam were measured according to JIS K6767. Also, those having a compression stress (25%) of less than 5 kPa were excellent in flexibility, and those having a compression set (24 hr) of less than 5% were excellent in recoverability.
Comparative Example 10
50 parts by weight of an ethylene-vinyl acetate copolymer (LV540: trade name) and a metallocene polyethylene resin (KS240: trade name: density: 0.880 g / cm ³ , MFR: 2.2 g / 10 minutes: manufactured by Nippon Polyethylene Co., Ltd.) ) Conventional foam LC-150G obtained by adding 0.7 parts by weight of dicumyl peroxide and 9.5 parts by weight of azodicarbonamide to a composition comprising 50 parts by weight (trade name: manufactured by Sanwa Kako Co., Ltd.) ), Apparent density 50 kg / m ³ , tensile strength 0.17 MPa, elongation 300%, 10% compression stress 3 kPa, 25% compression stress 5 kPa, 50% compression stress 8 kPa, 30 min compression set 5.6%, 24 hr compression permanent The strain was 2.9%.
Since the expansion ratio in the present invention is about 11 times (apparent density 84 to 89 kg / m ³ ), in order for the conventional foam to obtain the same flexibility as that in the present invention, 20 times (apparent density 50 kg / m). It was confirmed that an expansion ratio of m ³ : calculation formula: resin density ÷ apparent density × 1000) was required.
According to the present invention, an open cell body obtained by blending a metallocene-based polyethylene resin and an ethylene propylene diene copolymer rubber (EPDM) can be obtained, and the metallocene-EPDM resin-based open cell body has flexibility, elasticity, Since it has excellent recoverability, it can be applied to uses such as cushioning materials, heat insulating materials, and sound absorbing materials.

Claims (2)

A polyethylene resin (excluding a metallocene polyethylene resin) and / or a vinyl acetate resin is added to 100 parts by weight of a composition comprising 30 to 70 parts by weight of a metallocene polyethylene resin and 70 to 30 parts by weight of an ethylene propylene diene copolymer rubber. An apparent density of 84 to 89 kg / m is formed by heating and foaming a composition containing 0 to 40 parts by weight of a filler and 20 to 150 parts by weight of a filler to form closed cells and then forming open cells that communicate with the closed cells. ^3. Metallocene-ethylene propylene diene copolymer rubber-based open cell body. A polyethylene resin (excluding a metallocene polyethylene resin) and / or a vinyl acetate resin is added to 100 parts by weight of a composition comprising 30 to 70 parts by weight of a metallocene polyethylene resin and 70 to 30 parts by weight of an ethylene propylene diene copolymer rubber. An organic peroxide, a foaming agent, a foaming aid, a softening agent and a filler are added to a composition containing 0 to 40 parts by weight and 20 to 150 parts by weight of a filler, and then filled into a mold during pressing. A method for producing a metallocene-ethylenepropylene diene copolymer rubber-based open cell body, characterized by heating under pressure and further foaming at normal pressure and then making the bubbles continuous.