Molding composition

Details Molding composition Molding composition

2001-02-22

2001-10-09

Acquah, Samuel A. (Department: 1711)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Compositions to be polymerized by wave energy wherein said...

C524S401000, C524S450000, C524S498000, C525S391000, C525S397000, C525S425000, C525S540000, C522S104000

Reexamination Certificate

active

06300387

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a molding composition suitable for production of cores of automobile interior materials, sound absorbers of air conditioners, glass mat, constructional sound insulators, and the like.
BACKGROUND OF THE INVENTION
Cores of automobile interior materials, sound absorbers of air conditioners, glass mat, constructional sound insulators, and the like are produced from molding compounds mainly comprising fiber, a phenolic resin, and an amine curing agent to secure sufficient strength (see, for example, JP-A-57-55962 and JP-A-7-1666). However, phenolic resins react or decompose to produce formaldehyde, and the amine curing agent has the problem of smell.
Powdered molding compounds comprising a diallyl phthalate prepolymer and/or a crystalline unsaturated polyester resin, fiber, and a curing agent are known (see JP-A-5-169475). The diallyl phthalate prepolymer, however, has a low iodine value and fails to achieve a high crosslinking density, and generally used curing agent is used, so that the resulting molded article has insufficient strength.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a molded article having sufficient strength and heat resistance for practical use and improved safety and smell.
Another object of the present invention is to provide a molding composition suitable for producing such a molded article.
The present invention relates to a molding composition comprising (A) an aggregate, at least one of (B) an unsaturated polyester and (C) an unsaturated polyester-polyamide, and (D) a radical generator, wherein the radical generator (D) comprises a peroxide represented by formula (I):
R
1
OOC(CH
3
)
2
—R
3
—C(CH
3
)
2
OOR
2
  (I)
wherein R
1
and R
2
which may be the same or different, each represent an alkyl group having 3 to 10 carbon atoms or an arylalkyl group having 7 to 17 carbon atoms; and R
3
represents an arylene group.
The invention also relates to a molded article obtained by molding the molding composition.
DETAILED DESCRIPTION OF THE INVENTION
According to the present invention, use of a specific peroxide as a radical generator provides a molded article with sufficient strength for practical use and free from the problems of formaldehyde generation and smell.
The aggregate as component (A) includes a fibrous material and wood. The fibrous material is not particularly limited and includes inorganic fibers such as glass fiber and organic fibers such as synthetic resin fibers and natural fibers. Organic fibers of cotton, flax, wool, silk, wood fiber, nylon, etc. are preferred from the standpoint of flexibility and heat insulation of a molded article. Inorganic fiber and organic fiber can be used in combination. Component (A) can be used in the form of yarn or fabric, either woven or nonwoven.
The unsaturated polyester as component (B) is not particularly limited as long as it has a radical polymerizable unsaturated bond. The monomers providing component (B) are not particularly limited and comprise a di- or higher polyhydric alcohol component, a carboxylic acid component, such as a di- or higher polycarboxylic acid or an anhydride or an ester thereof, and, if necessary, a radical polymerizable unsaturated group-containing monomer. The radical polymerizable unsaturated group-containing monomer is essentially required where neither the alcohol component nor the carboxylic acid component contains a radical polymerizable unsaturated bond.
The carboxylic acid component is preferably used in an amount of 0.9 to 1.1 mol, particularly 0.95 to 1.05 mol, per mole of the alcohol component.
Preferred dihydric alcohol components include a bisphenol A-alkylene oxide adduct (containing 2 to 4 carbon atoms in the alkylene moiety; average mole number of alkylene oxide added: 1 to 10), ethylene glycol, propylene glycol, 1, 6-hexanediol, 1, 4-butanediol, bisphenol A, and hydrogenated bisphenol A. Still preferred of them are a bisphenol A-alkylene oxide adduct (containing 2 or 3 carbon atoms in the alkylene moiety; average mole number of alkylene oxide added: 2 to 5), ethylene glycol, 1, 4-butanediol, and hydrogenated bisphenol A. The alkylene oxide to be added is preferably ethylene oxide or propylene oxide. Two or more kinds of alkylene oxides may be added. For example, bisphenol A added with ethylene oxide and propylene oxide is preferred.
Preferred tri- or higher polyhydric alcohol components include sorbitol, 1,4-sorbitan, pentaerythritol, glycerol, and trimethylolpropane, with glycerol and trimethylolpropane being still preferred.
The dicarboxylic acid components include various dicarboxylic acids and succinic acid which is substituted with an alkyl group having 1 to 20 carbon atoms or alkenyl group having 1 to 20 carbon atoms, anhydrides of these acids, and alkyl esters of these acids having 1 to 12 carbon atoms in the alkyl moiety thereof. Maleic acid, fumaric acid, terephthalic acid, and C
2-20
alkenyl-substituted succinic acid (e.g., octenylsuccinic anhydride or dodecenylsuccinic anhydride) are preferred.
Preferred tri- or higher polycarboxylic acids include 1,2,4-benzenetricarboxylic acid (trimellitic acid), an anhydride thereof, and an alkyl ester thereof having 1 to 12 carbon atoms in the alkyl moiety.
The radical polymerizable unsaturated group-containing monomers include fumaric acid, maleic acid, maleic anhydride, and itaconic acid, with fumaric acid and maleic anhydride being preferred.
The unsaturated polyester-polyamide as component (C) is not particularly restricted as long as it has a radical polymerizable unsaturated bond. Component (C) can be obtained from a monomer mixture comprising an amine monomer in addition to the monomers used to prepare component (B). Examples of the amine monomers include various known polyamines, aminocarboxylic acids, amino alcohols, and lactams. Preferred amine monomers are metaxylenediamine, ethylenediamine, hexamethylenediamine, xylylenediamine, and &egr;-caprolactam.
It is desirable that each of components (B) and (C) be prepared from a monomer mixture comprising at least 20% by weight, particularly 30 to 70% by weight, especially 35 to 50% by weight, of at least one radical polymerizable unsaturated group-containing monomer based on the respective total constituent monomers. A molding composition comprising such components (B) and/or (C) exhibits satisfactory molding properties to provide a uniform molded article with further improved strength in ambient temperature and high temperature. The radical polymerizable unsaturated group-containing monomer(s) and the above-described other constituent monomers make 100% by weight. One or more kinds of component (B) and/or one or more kinds of component (C) can be used in combination.
Component (B) or component (C) can be prepared by allowing the respective monomer mixture to react at 150 to 250° C. for 5 to 20 hours in a nitrogen atmosphere. Component (B) and component (C) may be either a linear polymer or a nonlinear polymer. Since components (B) and (C) are used together with the radical generator (D) comprising a specific peroxide, the resulting molded and cured articles have increased hardness and strength as compared with those obtained with commonly employed radical generators. It is acceptable to use a monohydric alcohol component or a monocarboxylic acid component for molecular weight regulation, to use a generally used catalyst for esterification, such as dibutyltin oxide, for reaction acceleration. Additionally, polymerization inhibitor such as hydroquinone and t-butyl catechol may be used to prevent radical polymerization at condensation polymerization.
It is preferred for each of components (B) and (C) to have an iodine value of 40 or greater, still preferably 50 to 140, particularly 60 to 130, especially 70 to 130, to secure strength of molded articles. The iodine value is determined in accordance with JIS K0070.
It is preferred for each of components (B) and (C) to have a softening point of 80° C. or higher, particularly 80 to 130° C., for securing melting in molding and storage st

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