AQUEOUS DISPERSION OF a-OLEFIN-(METH)ACRYLIC ACID ESTER-BASED RUBBER PARTICLES, METHOD FOR PREPARING SAME, MOLDED BODY, AND RESORCIN-FORMALIN-LATEX ADHESIVE

Abstract

The present invention aims to provide an aqueous dispersion of α-olefin-(meth)acrylic acid ester-based rubber particles having better storage stability and ensuring better oil resistance of a molded body. The present invention also aims to provide a method for producing the aqueous dispersion, a molded body and a resorcin-formalin-latex adhesive each produced using the aqueous dispersion. The present invention relates to an aqueous dispersion of α-olefin-(meth)acrylic acid ester-based rubber particles including: an aqueous medium, a surfactant; and α-olefin-(meth)acrylic acid ester-based rubber particles, the aqueous dispersion containing the surfactant in an amount of 1 to 15 parts by mass relative to 100 parts by mass of the α-olefin-(meth)acrylic acid ester-based rubber particles.

Claims

1. An aqueous dispersion of α-olefin-(meth)acrylic acid ester-based rubber particles comprising: an aqueous medium, a surfactant; and α-olefin-(meth)acrylic acid ester-based rubber particles, the aqueous dispersion containing the surfactant in an amount of 1 to 15 parts by mass relative to 100 parts by mass of the α-olefin-(meth)acrylic acid ester-based rubber particles.

2. The aqueous dispersion of α-olefin-(meth)acrylic acid ester-based rubber particles according to claim 1, wherein the α-olefin-(meth)acrylic acid ester-based rubber particles are composed of an α-olefin-(meth)acrylic acid ester-based rubber containing at least one selected from the group consisting of an ethylene-(meth)acrylic acid ester copolymer, an ethylene-(meth)acrylic acid ester-unsaturated carboxylic acid copolymer, and an ethylene-vinyl acetate-(meth)acrylic acid ester copolymer.

3. The aqueous dispersion of α-olefin-(meth)acrylic acid ester-based rubber particles according to claim 1, wherein the α-olefin-(meth)acrylic acid ester-based rubber particles are composed of an α-olefin-(meth)acrylic acid ester-based rubber having a Mooney viscosity (ML.sub.1+4) measured at 100° C. in conformity with DIN53 523 of 5 to 80.

4. The aqueous dispersion of α-olefin-(meth)acrylic acid ester-based rubber particles according to claim 1, wherein the α-olefin-(meth)acrylic acid ester-based rubber particles have an average particle size of 0.1 to 5 μm.

5. The aqueous dispersion of α-olefin-(meth)acrylic acid ester-based rubber particles according to claim 1, wherein the surfactant contains at least one compound selected from the group consisting of a sulfosuccinate, a polyoxyalkylene (alkyl or alkenyl) ether sulfate, a fatty acid salt, and an ethylene oxide-propylene oxide copolymer.

6. The aqueous dispersion of α-olefin-(meth)acrylic acid ester-based rubber particles according to claim 1, further containing a polymeric dispersion stabilizer.

7. A method for producing the aqueous dispersion of α-olefin-(meth)acrylic acid ester-based rubber particles according to claim 1, the method comprising: a step of mixing an organic solution containing an α-olefin-(meth)acrylic acid ester-based rubber dissolved in an organic solvent and an aqueous solution containing a surfactant dissolved in an aqueous medium to prepare an emulsion; and a step of distilling off the organic solvent from the obtained emulsion.

8. A method for producing the aqueous dispersion of α-olefin-(meth)acrylic acid ester-based rubber particles according to claim 1, the method comprising: a step of mixing an α-olefin-(meth)acrylic acid ester-based rubber, a surfactant, and an aqueous medium to prepare a liquid mixture; and a step of emulsifying the obtained liquid mixture by heating to a temperature not lower than the softening temperature of the α-olefin-(meth)acrylic acid ester-based rubber.

9. A molded body produced using the aqueous dispersion of α-olefin-(meth)acrylic acid ester-based rubber particles according to claim 1.

10. A resorcin-formalin-latex adhesive comprising the aqueous dispersion of α-olefin-(meth)acrylic acid ester-based rubber particles according to claim 1, as a latex component.

Description

DESCRIPTION OF EMBODIMENTS

[0101] The present invention will be described in more detail with reference to, but not limited to, examples.

EXAMPLE 1

[0102] A 500-mL separable flask was charged with 20 parts by mass of Vamac G (available from Du Pont-Mitsui Polychemicals, Mooney viscosity of 16.5) as an α-olefin-(meth)acrylic acid ester-based rubber and 180 parts by mass of toluene, and the contents were stirred at 55° C. for four hours to be dissolved. To the obtained toluene solution was added an aqueous solution containing 1.0 parts by mass of potassium oleate as a surfactant dissolved in 100 parts by mass of water, and stirred with a homomixer (available from Primix Corporation, “Mark II 2.5 type”) for six minutes to prepare an emulsion. The number of rotations and temperature during the stirring were set to 12,000 rpm and 40° C. The obtained emulsion was heated to 40° C. to 70° C. under reduced pressure of 40 to 90 kPa for distillation of toluene, thereby preparing an aqueous dispersion of α-olefin-(meth)acrylic acid ester-based rubber particles.

EXAMPLE 2

[0103] A 500-mL separable flask was charged with 20 parts by mass of Vamac GLS (available from Du Pont-Mitsui Polychemicals, Mooney viscosity of 18) as an α-olefin-(meth)acrylic acid ester-based rubber, 162 parts by mass of toluene, and 18 parts by mass of isopropyl alcohol, and the contents were stirred at 60° C. for four hours to be dissolved. To the obtained organic solution was added an aqueous solution containing 0.8 parts by mass of sodium dioctylsulfosuccinate as a surfactant dissolved in 100 parts by mass of water, and stirred with a homomixer (available from Primix Corporation, “Mark II 2.5 type”) for six minutes to prepare an emulsion. The number of rotations and temperature during the stirring were set to 12,000 rpm and 40° C. The obtained emulsion was heated to 40° C. to 70° C. under reduced pressure of 40 to 90 kPa for distillation of toluene and isopropyl alcohol, thereby preparing an aqueous dispersion of α-olefin-(meth)acrylic acid ester-based rubber particles.

EXAMPLE 3

[0104] A 500-mL separable flask was charged with 20 parts by mass of DENKA ANX-3 (available from Denki Kagaku Kogyo Kabushiki Kaisha, Mooney viscosity of 45) as an α-olefin-(meth)acrylic acid ester-based rubber, 162 parts by mass of toluene, and 18 parts by mass of isopropyl alcohol, and the contents were stirred at 60° C. for four hours to be dissolved. To the obtained organic solution was added an aqueous solution containing 1.6 parts by mass of sodium polyoxyethylene lauryl ether sulfate as a surfactant dissolved in 100 parts by mass of water, and stirred with a homomixer (available from Primix Corporation, “Mark II 2.5 type”) for six minutes to prepare an emulsion. The number of rotations and temperature during the stirring were set to 12,000 rpm and 40° C. The obtained emulsion was heated to 40° C. to 70° C. under reduced pressure of 40 to 90 kPa for distillation of toluene and isopropyl alcohol, thereby preparing an aqueous dispersion of α-olefin-(meth)acrylic acid ester-based rubber particles.

EXAMPLE 4

[0105] A 1-L pressure-resistant autoclave equipped with a turbine type stirring blade (diameter: 50 mm) was charged with 160 parts by mass of Vamac GLS (available from Du Pont-Mitsui Polychemicals, Mooney viscosity of 18) as an α-olefin-(meth)acrylic acid ester-based rubber, 224 parts by mass of deionized water, and 16 parts by mass of an ethylene oxide-propylene oxide copolymer (available from ADEKA Corporation, “Pluronic F108”, mass average molecular weight of 15,500, ethylene oxide unit content of 80% by mass) as a surfactant, and sealed. Then, the stirrer was activated, and the temperature inside the autoclave was raised to 180° C. with stirring at the number of rotations of 500 rpm. Stirring was further kept for 15 minutes while the inside temperature was maintained at 180° C. The contents were then cooled to a room temperature, thereby preparing an aqueous dispersion of α-olefin-(meth)acrylic acid ester-based rubber particles.

EXAMPLE 5

[0106] An aqueous dispersion of α-olefin-(meth)acrylic acid ester-based rubber particles was prepared in the same manner as in Example 2, except that the amount of the sodium dioctylsulfosuccinate used as a surfactant was changed to 3.0 parts by mass.

EXAMPLE 6

[0107] An aqueous dispersion of α-olefin-(meth)acrylic acid ester-based rubber particles was prepared in the same manner as in Example 2, except that the amount of the sodium dioctylsulfosuccinate used as a surfactant was changed to 0.2 parts by mass.

COMPARATIVE EXAMPLE 1

[0108] An aqueous dispersion of α-olefin-(meth)acrylic acid ester-based rubber particles was prepared in the same manner as in Example 2, except that the amount of the sodium dioctylsulfosuccinate used as a surfactant was changed to 3.5 parts by mass.

COMPARATIVE EXAMPLE 2

[0109] The production process was carried out in the same manner as in Example 2, except that the amount of sodium dioctylsulfosuccinate as a surfactant was changed to 0.16 parts by mass. Then, lumps were formed during distillation of toluene, and an aqueous solution could not be obtained.

COMPARATIVE EXAMPLE 3

[0110] A chlorosulfonated polyethylene latex (available from Sumitomo Seika Chemicals Co., Ltd., “CEPOREX CSM”) was prepared as an aqueous dispersion.

<Evaluation>

[0111] The aqueous dispersions obtained in the examples and comparative examples were evaluated for the following parameters. Table 1 shows the results.

[0112] Since no aqueous dispersion was prepared in Comparative Example 2, the evaluation described below was not performed.

(Average Particle Size of Rubber Particles)

[0113] The average particle size of rubber particles of each of the aqueous dispersions obtained in Examples 1 to 6 and Comparative Example 1 was measured using a laser diffraction particle size analyzer (available from Shimadzu Corporation, “SALD-2000)”).

(Storage Stability)

[0114] A 50-mL container was charged with 40 g of each of the aqueous dispersion obtained in Examples 1 to 6 and Comparative Example 1, sealed, and left in an environment of a temperature at 25° C. The state of the aqueous dispersion was visually checked after three months. The storage stability was evaluated based on the following criteria: the case where no phase separation was observed was rated “∘(good)”; the case where phase separation was partially observed was rated “Δ(fair)”; and the case where complete phase separation was observed was rated “×(poor)”.

(Bleeding of Surfactant)

[0115] An amount of 10 g of each of the aqueous dispersions obtained in Examples 1 to 6 and Comparative Example 1 was placed in a Petri dish (φ120 mm) and dried at 40° C. for 12 hours to give a coating film. The state of the obtained coating film was visually observed. Bleeding of the surfactant was evaluated based on the following criteria: the case where bleeding of the surfactant from the surface of the coating film was not observed was rated “∘(good)”; the case where slight bleeding of the surfactant from the surface of the coating film was observed was rated “Δ(fair)”; and the case where much bleeding of the surfactant from the surface of the coating film was observed was rated “×(poor)”.

(Oil Resistance)

[0116] An amount of 220 g of each of the aqueous dispersions obtained in Examples 1 to 6 and Comparative Examples 1 and 3 was placed in a Petri dish (φ120 mm) and dried at 80° C. for 12 hours to give a coating film. The obtained coating film was sandwiched between Teflon (®) sheets and molded under pressure at 20 Mpa and 120° C. for one minute using a press machine, thereby preparing a sheet with a thickness of about 2 mm. An amount of 2 g of the obtained sheet was immersed in 30 g of a motor oil (available from Toyota Motor Corporation, “Toyota Castle SN 0W-20”) at 150° C. for 10 hours. The mass of the sheet before and after the immersion in the motor oil was measured to obtain the mass increasing rate due to the immersion.

[0117] A smaller mass increase means better oil resistance. When the mass increasing rate is 20% or lower, the oil resistance is better.

TABLE-US-00001 TABLE 1 Example Comparative Example 1 2 3 4 5 6 1 2 3 Composition α-olefin- Vamac G 20 — — — — — — — — (parts by (meth)acrylic (Du Pont-Mitsui Polychemicals, mass) acid ester- Mooney viscosity of 16.5) based rubber Vamac GLS — 20 — 160 20 20 20 20 — (Du Pont-Mitsui Polychemicals, Mooney viscosity of 18) DENKA ANX-3 — — 20 — — — — — — (Denka Company Ltd., Mooney viscosity of 45) Surfactant Potassium oleate 1.0 — — — — — — — — Sodium dioctylsulfosuccinate — 0.8 — — 3.0 0.2 3.5 0.16 — Sodium polyoxyethylene — — 1.6 — — — — — — lauryl ether sulfate Ethylene oxide-propylene — — — 16 — — — — — oxide copolymer Aqueous medium Water 100 100 100 224 100 100 100 100 — Chlorosulfonated polyethylene latex — — — — — — — — 100 (Sumitomo Seika Chemicals Co., Ltd., “CEPOREX CSM”) Amount of surfactant relative to 100 parts by mass of 5.0 4.0 8.0 10 15 1.0 17.5 0.8 — α-olefin-(meth)acrylic acid ester-based rubber particles (parts by mass) Evaluation Average particle size of rubber particles (μm) 3.0 0.6 2.5 1.0 0.5 4.5 0.4 — — Storage stability ∘ ∘ ∘ ∘ ∘ Δ ∘ — — Bleeding of surfactant ∘ ∘ ∘ ∘ Δ ∘ x — — Oil resistance (mass increasing rate (%)) 20 14 16 14 15 14 18 — 107 * An aqueous dispersion could not be prepared in Comparative Example 2.

[0118] Table 1 shows that the aqueous dispersions produced in Examples 1 to 5 are better in storage stability.

[0119] Bleeding of the surfactant was not observed in the molded bodies (coating films) obtained from the aqueous dispersions produced in Examples 1 to 4 and 6. By contrast, bleeding of the surfactant was observed in the molded body (coating film) obtained from the aqueous dispersion produced in Comparative Example 1.

[0120] In addition, all of the coating films obtained from the aqueous dispersions produced in Examples 1 to 6 were better in oil resistance, with the mass increasing rate of 20% or less in the evaluation of the oil resistance. By contrast, the coating film obtained from the latex of Comparative Example 3 had poor oil resistance with the mass increasing rate of higher than 100% in the evaluation of the oil resistance.

[0121] As above, the aqueous dispersion of α-olefin-(meth)acrylic acid ester-based rubber particles of the present invention is an aqueous dispersion having better storage stability and ensuring better oil resistance of a molded body.

INDUSTRIAL APPLICABILITY

[0122] The present invention provides an aqueous dispersion of α-olefin-(meth)acrylic acid ester-based rubber particles having better storage stability and ensuring better oil resistance of a molded body. The present invention also provides a, method for producing the aqueous dispersion, and a molded body and a resorcin-formalin-latex adhesive each produced using the aqueous dispersion.