Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
2001-05-02
2003-05-06
Foelak, Morton (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C521S075000, C521S128000, C521S137000
Reexamination Certificate
active
06559193
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to an acrylic sol for a sound insulating underbody coating. More particularly, it relates mainly to an acrylic sol which gives automotive steel plates, etc., a chipping resistance, a sound insulating performance, and so on, when it is coated on the exterior bottom surface of the underbody, wheel houses, and the like, of automobiles.
In the bottom surface of the underbody, wheel houses, etc., of automobiles, there occurs a so-called chipping phenomenon in which a paint film is come off by colliding with small stones and gravels being flied up by tires while automobiles are driving. Moreover, there arise colliding sounds, so-called splash noise, resulting from the collisions of the small stones and gravels. Accordingly, in order to inhibit the chipping phenomenon and to reduce the splash noise, a sound insulating underbody coating, which employs a polyvinyl chloride-based plastisol, has been coated and dried conventionally on a surface of an automotive steel plate, which has gone through a coating process, so that a paint film for protecting an automotive body is formed.
While, in view of protecting the environment of the earth, it is expected to recycle the materials which are used in automotive bodies. It is desired that they are used as a thermal energy by burning them, not by the current practice, for example, by burying them as shredded dusts in the land.
However, the aforementioned vinyl chloride plastisol generates the hydrogen chloride gas, which becomes a source of substances causing the destruction of the ozone layer. Further, the resulting hydrogen chloride causes the acid rain. Furthermore, the polyvinyl chloride-based plastisol has a problem in that they generate dioxins when they are burned. Consequently, a plastisol for a sound insulating underbody coating, plastisol which can replace the polyvinyl chloride-based plastisol, has been longed for.
As a plastisol, which substitutes for the polyvinyl chloride-based plastisol, Japanese Unexamined Publication (KOKAI) No. 6-145,454 discloses an acrylic ester-based copolymer plastisol, which includes particles and a plasticizer. The particles are composed of ion cross-linked substances, in which carboxyl groups of a copolymer are cross-linked by adding monovalent or divalent metallic cations. The copolymer includes the following units as main constituent units in specific rates. For instance, the copolymer includes alkyl methacrylate ester units, in which a number of the carbon atoms in the alkyl groups falls in a specific range, diene-based monomer units, and a radically polymerizable unsaturated carboxylic acid, which has a carboxyl group and has a specific number of the carbon atoms.
Further, Japanese Unexamined Patent Publication (KOKAI) No. 7-233,299 discloses an acrylic plastisol, which includes acrylic polymer fine particles. The acrylic polymer fine particles are composed of a core portion and a shell portion, and accordingly have a multi-layered structure of two layers at least.
Furthermore, Japanese Examined Patent Publication (KOKOKU) No. 63-66,861 discloses a plastisol, which does not contain the polyvinyl chloride. For example, the plastisol is composed of a methyl methacrylate polymer or copolymer, a plasticizer, a filler, a blocked polyisocyanate, and a polyamine.
Although the plastisols, which are disclosed in Japanese Unexamined Patent Publication (KOKAI) No. 6-145,454 and Japanese Unexamined Patent Publication (KOKAI) No. 7-233,299, are free from the drawbacks associated with the aforementioned polyvinyl chloride-based plastisol, they are not sufficient in terms of the adhesion property of the resulting paint film to a substrate and the cold resistance. In addition, it is not possible to obtain the advantageous effects in terms of the requisite performances for the sound insulating underbody coating, such as the inhibition of the chipping phenomenon and the reduction of the splash noise, with these plastisols as described above.
In addition, the plastisol disclosed in Japanese Examined Patent Publication (KOKOKU) No. 63-66,861 is likewise free from the drawbacks associated with the polyvinyl chloride-based plastisol. However, it is not possible to say that the plastisol can be satisfactory in terms of the requisite performances for the sound insulating underbody coating, such as the inhibition of the chipping phenomenon and the reduction of the splash noise. Therefore, it is not possible to employ these plastisols as a plastisol for a sound insulating underbody coating, plastisol which can substitute for the polyvinyl chloride-based plastisol.
SUMMARY OF THE INVENTION
The present invention has been developed in view of the above-described circumstances. It is an object of the present invention to provide an acrylic sol for a sound insulating underbody coating, acrylic sol which effects a favorable chipping resistance and a sufficient sound insulating performance without generating the hydrogen chloride gas and the dioxins when it is burned.
An acrylic sol for a sound insulating underbody coating according to the present invention, which is adapted to achieve the aforementioned object, is characterized in that it comprises: acrylic polymer fine particles; a plasticizer; a filler; a blocking type urethane resin; a curing agent; and a foaming agent.
As the present acrylic sol includes the acrylic polymer fine particles as a major constituent member, it is possible to obtain an acrylic sol for a sound insulating underbody coating, which is free from the aforementioned drawbacks associated with the sound insulating underbody coating whose major constituent member is the conventional vinyl chloride plastisol. Namely, the present acrylic sol does not generate the hydrogen chloride gas as well as the dioxins when it is burned. Further, when the acrylic polymer fine particles are a core-shell structure, the present acrylic sol makes a sol for a sound insulating underbody coating, in which the storage stability of the thus prepared acrylic sol is further improved, which is further inhibited from the increment of the viscosity during the coating, and which is further prohibited from the generation of the bleeding after the curing by heating.
Furthermore, as the present acrylic sol includes the blocking type urethane resin and its curing agent, the cross-linkage reactions take place by the intermolecular cross-liking of the urethane resin when the thus prepared acrylic sol is coated and is heated thereafter. Since the urethane resin takes the net-shaped structure by the cross-linkage reactions, it is possible to obtain an acrylic sol for a sound insulating underbody coating, acrylic sol which makes a paint film of favorable cold resistance, of favorable adhesion property to automotive steel plates and of superb chipping resistance. Note that, when a weight ratio of the acrylic polymer fine particles with respect to the blocking type urethane resin falls in a range of from 90/10 to 15/85, the present acrylic sol makes an acrylic sol for a sound insulating underbody coating, acrylic sol which can result in a paint film, whose cold resistance, adhesion property to automotive steel plates and chipping resistance are furthermore improved, and which can bring about a favorable coating operability.
Furthermore, when the blocking type urethane resin is blocked by at least one member selected from the group consisting of oxime blocking agents and amine blocking agents, the blocking agents dissociate at a relatively low temperature so that the reactions with the curing agent can be developed. Accordingly, the present acrylic sol can make an acrylic sol for a sound insulating underbody coating, acrylic sol which can be gelled at a much lower temperature so as to form a paint film.
Moreover, when the curing agent is a solid hydrazine-compound curing agent, it reacts with the urethane resin at a relatively low temperature. Consequently, the present acrylic sol can make an acrylic sol for a sound insulating underbody coating, acrylic sol which can be
Ito Kazunori
Nonoyama Akira
Ohashi Yutaka
Takata Ayumi
Torii Hiroshi
Aisin Kako Kabushiki Kaisha
Foelak Morton
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