Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-07-20
2001-04-24
Szekely, Peter (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C523S500000, C523S513000, C523S514000, C523S521000, C523S527000, C523S218000, C523S219000
Reexamination Certificate
active
06221935
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to resin concrete compositions from which molded articles having no cracks can be obtained with little shrinkage without using a shrinkage reducing agent as well as being excellent in flowability and the hardened articles thereof having high strengths even with reduced resin contents. The present invention also relates to molded articles of the resin concrete compositions.
2. Description of Related Art
Resin concrete compositions containing an unsaturated polyester resin composition which incorporate an unsaturated polyester and a polymerizable unsaturated monomer, an aggregate, and a filler have been known, and industrially, resin concrete compositions have been used for products related to water supply and sewers, such as manholes, pipes, and drainage basins, for repairing cracks in cement concrete, for molded articles for landscaping such as garden lanterns, and for the like. Conventional resin concretes, particularly those having no coarse aggregate and having a relatively high resin content such as 15 to 20%, normally incorporate a shrinkage reducing agent consisting of a thermoplastic resin such as polystyrene and polyvinyl acetate in order to avoid cracking due to shrinkage during hardening in a molding process, and clinging to the mold.
However, since a shrinkage reducing agent itself cannot be hardened, problems such as the following have occurred:
The obtained molded article has a reduced strength.
The surface of the molded article becomes sticky.
The molded products are irregular in their dimensions and strength because of differences in shrinkage reducing effect due to different temperatures of the exothermic reaction during hardening, caused by variations in seasons, atmospheric temperatures, temperatures in the curing oven, or the like.
With a certain type of shrinkage reducing agent, the appearance of the molded product deteriorates since the shrinkage reducing agent is poorly compatible with the unsaturated polyester resin, and therefore when they are combined to make a resin concrete, the flowability and the ease of degassing are degraded.
The necessity of increasing the resin content results in an increase in the cost.
In addition, use of dicyclopentadiene-modified unsaturated polyester as the unsaturated polyester in the resin concrete has been known, for example, as disclosed in International Publication No. WO87/04442 and Japanese Unexamined Patent Application, First Publication (Kokai) No. Hei 4-149050. However, there were problems in that the strengths of the resin concrete molded articles were low, and the cracking resistance was insufficient.
BRIEF SUMMARY OF THE INVENTION
An object of the present invention is to provide a resin concrete composition which shrinks little and is highly flowable, that is, a resin concrete composition which, even with a reduced resin content, has an excellent flowability, which is an important property in a molding operation, and necessitates no shrinkage reduction agent, and a molded article of which has no cracks and is very strong. Another object of the present invention is to provide such a molded article.
As a result of diligent research in the above objects, the present inventors have achieved the present invention.
The present invention provides a resin concrete composition and a molded article thereof, the resin concrete composition comprising (A) a resin composition containing (a) an unsaturated polyester of an unsaturated acid, a di- and/or trialkylene glycol, and dicyclopentadiene and (b) a polymerizable unsaturated monomer, (B) an aggregate, and (C) a filler. Preferably, the amount of dicyclopentadiene to be incorporated in the unsaturated polyester is 1 to 55% by weight. Preferably, the proportion of the unsaturated polyester (a) is 80 to 60 parts by weight, and the proportion of the polymerizable unsaturated monomer (b) is 20 to 40 parts by weight, with respect to 100 parts by weight of the total amount of the unsaturated polyester (a) and the polymerizable unsaturated monomer (b). In addition, preferably, the number-average molecular weight of the unsaturated polyester (a) is 400 to 1500.
The present invention will be described in detail in the following.
DETAILED DESCRIPTION OF THE INVENTION
A resin concrete composition according to the present invention may be used for products related to water supply and sewers, such as manholes, pipes, and drainage basins, for repairing cracks in cement concrete, for molded articles for landscaping such as garden lanterns, and for the like, and comprises a resin, an aggregate, and a filler.
The resin concrete composition according to the present invention comprises an unsaturated polyester resin composition (A) containing an unsaturated polyester (a) and a polymerizable unsaturated monomer (b), an aggregate (B), and a filler (C). When hardening is performed, the resin concrete composition further comprises a hardening accelerator (D) and a hardener (E).
For the unsaturated polyester (a) used in the present invention, an unsaturated acid (a1), a di- and/or trialkylene glycol (a2), and dicyclopentadiene (a3) are used as raw materials. The unsaturated acid (a1) may be an unsaturated dibasic acid such as maleic anhydride and fumaric acid. If the necessity of adjusting the exothermic temperature during hardening, or adjusting the properties of the unsaturated polyester arises, a saturated dibasic acid such as orthophthalic acid, isophthalic acid, terephthalic acid, adipic acid, and the like may be used together to such an extent that it does not deteriorate the effects of the invention.
The di- and/or trialkylene glycol (a2) may be selected from dialkylene glycols such as diethylene glycol and dipropylene glycol and trialkylene glycols such as triethylene glycol. In order to impart desirable resin concrete properties which are suitable for application, an alkylene glycol such as ethylene glycol, propylene glycol, and butylene glycol may be used together to such an extent that it does not deteriorate the effects of the invention.
The amount of the dicyclopentadiene (a3) may be 1 to 55% by weight, preferably 25 to 50% by weight, of the raw material components of the unsaturated polyester (a).
Examples of processes for producing the unsaturated polyester modified by dicyclopentadiene are as follows, any of which may be applied to the present invention:
(1) A one-step synthetic process in which the modification occurs concurrently by putting the acid, the glycol, and dicyclopentadiene in a vessel at the same time and condensing them.
(2) A two-step synthetic process in which the acid and the glycol are condensed, and in the middle of the condensation dicyclopentadiene is added thereto to let the modification proceed.
(3) A process in which an addition reaction is allowed to occur between an acid anhydride and dicyclopentadiene in the presence of water to produce a monoester, and thereafter the glycol and the acid are added thereto and the reaction is allowed to occur.
In addition, endo-methylenetetrahydrophthalic acid may be present, which is produced from the reaction between cyclopentadiene, which is generated by a thermal dissociation of dicyclopentadiene, and the unsaturated acid. The unsaturated polyester (a) of the present invention preferably has a structure which is obtained by the addition reaction of the unsaturated acid (a1) to the di- and/or trialkylene glycol (a2), then the addition reaction of dicyclopentadiene.
For the polymerizable unsaturated monomer (B) in the present invention, one which is normally used in an unsaturated polyester resin composition may be used to such an extent that it does not deteriorate the effects of the invention. Examples thereof are styrene, &agr;-methylstyrene, chlorostyrene, dichlorostyrene, divinylbenzene, t-butylstyrene, vinyltoluene, vinyl acetate, diaryl phthalate, triaryl cyanurate, acrylic ester, methacrylic ester, and the like; and an unsaturated monomer or unsaturated oligomer which is crosslinkable with the resin, such as methyl (meth)acrylat
Furuya Yutaka
Hashimoto Yoshitomi
Kanai Toshio
Armstrong Westerman Hattori McLeland & Naughton LLP
Dainippon Ink and Chemicals Inc.
Szekely Peter
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