Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From aldehyde or derivative thereof as reactant
Patent
1997-01-30
1999-02-02
Truong, Duc
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From aldehyde or derivative thereof as reactant
528 23, 43 56, C08G 400
Patent
active
058666710
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Industrial Use Field
This invention pertains to molded parts used for photographic sensitive materials and resin compositions used to make such parts as magazines which house photographic sensitive materials like photo-film and printing paper or springs and rollers that are used around the photographic sensitive materials.
2. Existing Technology
Polyacetal resin which is a thermoplastic resin is used as a molding composition for machine bearings, gear wheels, rollers, cams, clips and plate springs because of its excellent mechanical properties, heat resistance, friction resistant and anti-abrasion properties and fatigue resistance property. However, a small amount of the monomer formaldehyde is dissolved in molded parts made of the polyacetal resin and its slow release into the air causes deterioration of work environment and compromized work efficiency and, in some cases, may lead to harmful result to the end use objective. For example, because chemically active formaldehyde is present, the polyacetal resin causes some concern to be used as food and medical packaging material.
Also, it is known that formaldehyde has detrimental effect on photographic sensitive materials such as photographic film and printing paper. While a silver halide emulsion is used in these photographic sensitive materials, formaldehyde has the ability to reduce silver halides, resulting in chemical fogging. Therefore, polyacetal resins, in general, cannot be used as a resin composition of magazines that receive photographic sensitive materials and various molded parts that are used around them. Consequently, metals are often used to make parts that require sufficient elasticity such as a film pressing board.
Considering these situations and in order to reduce concentrations of formaldehyde gas in the molded parts made of acetal resin, Japanese Kokai 1992-34548 describes hydrazide compounds to be used as an additive, and Japanese Kokai 1994-107900 describes the use of fatty acid ester of polyvalent alcohol compound as an additive.
Problems that Invention Attempts to Solve
But, when a hydrazide compound is added as an additive to polyacetal resin, there is a certain danger of its byproduct, hydrazine itself, functioning as a reducing agent of photographic sensitive materials. Also, when a fatty acid ester of polyvalent alcohol compound is used as an additive, its effect to suppress formaldehyde is not sufficiently and practical problems persist for its use as a resin composition to make molded parts for photographic sensitive materials.
SUMMARY OF THE INVENTION
Resin compositions used to make parts for photographic sensitive materials, which are polyacetal resin compositions and are characterized by the concentration of formaldehyde generated from a formed object of the said composition in a closed environment being less than 20 ppm and by not compromizing with their photographic properties.
This invention is to solve the problems described above and aims at making polyacetal resins that possess excellent characteristics in mechanical properties, heat resistance and fatigue resistance suitable to be a resin composition material to make molded parts used for photographic sensitive materials.
BRIEF DESCRIPTION OF FIGURES
FIG. 1 is a schematic perspective view of an instant film pack used in the invention.
FIG. 2 is a graph showing a correlation of formaldehyde concentration and fogging concentration. Abscissa, left and right ordinates are for the amounts of Additive-2 (weight %), the formaldehyde concentration (ppm) and the fogging concentration (Dmin), respectively. The top solid plot is for the fogging concentration at blue and the lower broke line plot is for the residual formaldehyde concentration.
FIG. 3 is a graph showing a correlation between the amount of added 5,5-dimethylhydantoin and the bending elasticity. The abscissa is the amount of Additive 2 (weight %) and the ordinate is the bending elasticity (.times.10 kg/cm).
DETAILED DESCRIPTION
Method to Solve Problems
In order to achieve t
REFERENCES:
patent: 3333520 (1967-08-01), McGivney
patent: 4127382 (1978-11-01), Perry
PCT International Search Report (PCT/US 95/09798).
G. Deraedt "Methods of abating residual formaldehyde in industrial resins" 1988, Pergamon Press, Oxford GB
see abstract US 4127382 (Perry R.S.) see p. 20.
see abstract EP 43036 (Vianova Kunstharz) see p. 52.
Kassal Robert J.
Shinohara Ken-ichi
Suzuki Osamu
Yoneyama Takashi
E. I. Du Pont de Nemours and Company
Truong Duc
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