Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2000-09-11
2003-02-11
Lovering, Richard D. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C516S077000, C516S920000, C523S340000, C524S060000
Reexamination Certificate
active
06518354
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a dispersing emulsion of a thermoplastic elastomer, a process for preparing the same, and an asphalt modifier imparting preferable properties to asphalt. In particular, the present invention relates to a dispersing emulsion of a thermoplastic elastomer having storage stability and mechanical stability of the dispersing emulsion improved by using a specific nonionic emulsifier as an emulsifier for emulsification and dispersion, the other emulsifiers used as an optional component and a thickener, as well as a process for preparing the same, and an asphalt modifier comprising the water-based dispersing solution.
BACKGROUND ART
There is disclosed a block copolymer latex emulsified with a block copolymer represented by the general formula:
A-B-A, (A-B)n, B-(A-B)n, (A-B)n-A or A-B-(B-A)n
(wherein A is a non-elastic polymer block having a secondary transition temperature of at least 25° C., B is an elastic polymer block having a secondary transition temperature of at most 10° C., and n is an integer of at least 2), and as an emulsifier with (a) a rosin ester or a heterogeneous rosin ester and (b) a compound represented by the general formula:
(wherein R
1
is an alkyl group containing 8 to 18 carbon atoms or an alkyl phenyl group having an alkyl group containing 8 to 12 carbon atoms, R
2
is an alkylene group containing 2 to 5 carbon atoms, and m is an integer of 3 to 50) and as an optional component with a thickener (methyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, casein, poly(acrylic acid) or a derivative thereof (Japanese Examined Patent Publication No.52-22651/1977).
As the similar technique to the block copolymer latex, there is disclosed a copolymer latex of styrene and butadiene, wherein (a) higher fatty acid, rhodinic acid or heterogeneous rhodinic acid, and (b) a
compound represented by the general formula:
(wherein R
1
is an alkyl group containing 8 to 18 carbon atoms or an alkyl phenyl group having an alkyl group containing 8 to 12 carbon atoms, R
2
is an alkylene group containing 2 to 5 carbon atoms, and n is an integer of 3 to 50) as emulsifiers are dissolved in a polymer solution comprising a random copolymer of styrene and butadiene, a binary block copolymer of styrene and butadiene or a mixture thereof obtained as a copolymer latex of styrene and butadiene by solution polymerization, and then mixed and emulsified with an aqueous alkali solution (Japanese Examined Patent Publication No.52-15100/1977 and Japanese Unexamined Patent Publication No.51-13847/1976).
However, the block copolymer latex and the copolymer latex of styrene and butadiene have the problem that storage stability or mechanical stability is not always satisfactory.
In recent years, there has been developed asphalt (modified asphalt) having viscosity at 60° C., toughness, tenacity, temperature sensitivity and the like improved by adding a modifier comprising polymer materials such as a rubber and a resin (containing a thermoplastic elastomer, hereinafter as the same) to asphalt and it has been used for improving rutting resistance, abrasion resistance and the like of road.
As the modifier, there is disclosed an asphalt modifier in the form of an aqueous dispersing emulsion with an average particle diameter of at most 5 &mgr;m (Japanese Unexamined Patent Publication No.2-292368/1990). The modifier is obtained by dissolving the thermoplastic elastomer into an organic solvent, adding an emulsifying dispersant containing a poly(alkylene oxide) group-containing anionic surfactant as a major component and a nonionic surfactant as an optional component thereto in an amount of at most 10% by weight based on the elastomer, and then adding hot water to emulsify the resulting mixture, and removing the organic solvent.
Examples of the poly(alkylene oxide) group-containing anionic surfactant and the nonionic surfactant as the optional component are poly(oxyethylene nonyl phenol ether) sodium sulfate (an adduct with 4 moles of ethylene oxide), poly(oxyethylene dodecyl ether) sodium acetate (an adduct with 3 moles of ethylene oxide) and poly(oxyethylene nonyl phenol ether) (an adduct with 4 moles of ethylene oxide).
However, the asphalt modifier, the block copolymer latex and the copolymer latex of styrene and butadiene, which can be used as the asphalt modifier, have the problem that storage stability or mechanical stability is not always satisfactory. Further, because all of them are emulsions mainly comprising an anionic surfactant, it is difficult to be mixed with a cationic asphalt emulsion as a major group of an asphalt emulsion, and it is impossible to be used for modifying a cationic asphalt emulsion.
DISCLOSURE OF INVENTION
The present invention is made to solve the problems in the prior art described above. Namely, the present invention relates to a dispersing emulsion of a thermoplastic elastomer, which is emulsified and dispersed in the presence of at least one nonionic emulsifier selected from the group consisting of a styrenated phenol poly(alkylene oxide), a poly(alkylene polyamine) poly(alkylene oxide), polyalcohol fatty acid esters, polyalcohol fatty acid esters poly(alkylene oxide) and a benzylated phenol poly(alkylene oxide).
Further, the present invention relates to a process for preparing the dispersing emulsion, which comprises preparing a solution containing at least one nonionic emulsifier selected from the group consisting of a styrenated phenol poly(alkylene oxide), a poly(alkylene polyamine) poly(alkylene oxide), polyalcohol fatty acid esters, polyalcohol fatty acid esters poly(alkylene oxide) and a benzylated phenol poly(alkylene oxide) dissolved in a solution comprising thermoplastic elastomer and an organic solvent, then emulsifying the solution by mixing with water, and distilling the organic solvent.
In addition, the present invention relates to an asphalt modifier comprising the aqueous dispersing emulsion.
BEST MODE FOR CARRYING OUT THE INVENTION
The thermoplastic elastomer used in the present invention, when used as e.g. an aqueous pressure-sensitive adhesive, is used as a component for improving a holding strength at a high temperature by mixing it with an acrylic aqueous pressure-sensitive adhesive. In addition, the thermoplastic elastomer, when added to an SBR latex for water based chipping-resistant coating, is used as a component excellent in compatibility with SBR and capable of improving chipping resistance and adhesion.
Especially, the thermoplastic elastomer is preferably the one, which is excellent in compatibility with asphalt and is capable of improving softening point, viscoelasticity, toughness, high-temperature viscosity and low-temperature flexibility of asphalt when added to asphalt.
As the thermoplastic elastomer, there is no particular limitation therefor, as long as it is conventionally used for the above- described purposes. Examples thereof are block copolymers used as hot-melt adhesive and represented by the general formula:
A-B-A, (A-B)
n
, B-(A-B)
n
and (A-B)
n
-A, A-B-(B-A)Z
n
wherein A is a non-elastic polymer block having a secondary transition temperature of at least 25° C., B is an elastic polymer block having a secondary transition temperature of at most 10° C., and n is an integer of at least 2.
Examples of the non-elastic polymer block are a homopolymer block of a monomer selected from monovinyl aromatic hydrocarbons such as styrene and &agr;-methylstyrene, a copolymer block comprising at least 2 of these monomers; a copolymer block of a monovinyl aromatic hydrocarbon and the tapered aliphatic conjugated diene compound of the following B block component; and a random copolymer block of a monovinyl aromatic hydrocarbon and the aliphatic conjugated diene compound of the following B block component. Examples of the blocks are blocks of a styrene polymer, a copolymer of styrene and &agr;-methylstyrene, a copolymer of styrene and tapered butadiene or isoprene, and a random copolymer of styrene and butadiene or isoprene. Molecular weight thereof is generally 1,000 to 200,000, prefera
Kuze Masayo
Nishitani Toshiyuki
Okubo Yukihiro
Suzuki Ginpei
JSR Corporation
Lovering Richard D.
Sughrue & Mion, PLLC
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