Stock material or miscellaneous articles – Hollow or container type article – Paper containing
Reexamination Certificate
2002-07-09
2004-09-21
Lechert, Jr., Stephen J. (Department: 1732)
Stock material or miscellaneous articles
Hollow or container type article
Paper containing
C428S035600, C428S035700, C428S036920, C524S009000, C524S014000, C524S034000, C264S405000, C264S122000, C264S123000
Reexamination Certificate
active
06793992
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a molded product for a cushioning material (hereinafter referred to as “cushioning molding product”) composed mainly of a vegetable fiber, and to a process for production and recovery thereof.
2. Related Background Art
Molded products produced by binding and molding a vegetable fiber such as paper, cotton, straw, and strained lees with a suitable binder are widely used as a cushioning material for impact absorption.
In recent years, molded pulp products are coming to partially replace conventional foamed polystyrene-molded products used as a cushioning packing material for home electric appliances. The molded pulp products exhibit excellent properties of absorbing drop-impact and sound-wave, and readily moldable into sheets, pellets, or an arbitrary shape to fit to the shape of the package.
The molded pulp product is basically a paper product, and can readily be regenerated after use by fiber opening and sheet making. Besides, in the case where the regeneration is not suitable owing to the deterioration of the properties or other reasons, the molded pulp product can be burned or buried without releasing a toxic component to cause less adverse effect on the environment. Especially, the molded pulp product is advantageous from the standpoint of effective utilization of resources.
Various binders are used for producing the cushioning molded products. As the binders, polysaccharides are widely used in consideration of compatibility with the vegetable fiber and low environmental loading, the polysaccharides including starches, agars, mannan, alginic acid, and carboxymethylcellulose.
These polysaccharides, however, do not always have good processability because of insolubleness in solvents except water, lack of thermoplasticity, or other reasons. Use of a usual thermoplastic resin is disclosed (Japanese Patent Application Laid-Open No. 7-267276). However, the usual thermoplastic resin does not have sufficient compatibility with vegetable fibers. The polysaccharides are derived from a material other than the fiber.
The molded pulp product has disadvantages resulting from the production process. That is, molded pulp products are conventionally produced by a wet sheet-making process employing water, similarly as paper sheets. This process comprises drying of an aqueous slurry, requiring a long time and consuming much energy for the drying, and the productivity thereof is not high. In particular, this production process is disadvantageous for production of thick molded products of less directional dependence in cushioning properties for drop impact. Moreover, the large energy consumption generally causes emission of carbon dioxide gas, which is a cause of greenhouse effect. This is inconsistent with the intension of environmental protection of the molded pulp product itself.
The present invention intends to provide a cushioning molded product, which is excellent in strength, processability and recyclability, produced from a vegetable fiber as the main source material by maximally utilizing the feature of the vegetable fiber. The present invention intends to also provide the process for production of the cushioning molded product.
The present invention further intends to provide a process of producing the cushioning molded products from the vegetable fiber as the main source material with higher productivity and lower environmental loads.
SUMMARY OF THE INVENTION
The present invention provides a cushioning molded product produced by binding a vegetable fiber with a copolymer of a saccharide and an aliphatic dicarboxylic acid to conduct molding.
In a preferred embodiment, the vegetable fiber is paper or a fiber obtained by fiber opening of paper.
The saccharide is preferably a monosaccharide or an oligosaccharide with a polymerization degree of 6 or less. The saccharide may be partially substituted with an acetyl group. The number of substituting acetyl groups is preferably in the range of 0 to 2 per monosaccharide unit.
In a preferred embodiment of the present invention, the saccharide is a product of decomposition of a vegetable fiber, in particular, a product of decomposition of paper.
The aliphatic dicarboxylic acid preferably has an alkylene chain having 4 to 10 carbon atoms for the monosaccharide, and 6 to 10 carbon atoms for the oligosaccharide.
The vegetable fiber is contained at a content ranging preferably from 50 to 99 wt %, and the copolymer is contained at a content ranging preferably from 1 to 50 wt %.
The copolymer preferably contains a component with a weight-average molecular weight of 500 to 10000 at a content from 50 to 100 wt %.
The present invention also provides a process for producing the cushioning molded product from a copolymer of a saccharide and an aliphatic dicarboxylic acid, and a vegetable fiber, the process comprising:
(a) mixing or adhering the copolymer and the vegetable fiber, and
(b) molding a mixture resulting from step (a) into an intended shape by heating the mixture to bind the vegetable fiber with the copolymer.
In a preferred embodiment, the mixing step includes a step of mixing the copolymer and the vegetable fiber by use of a solvent containing water at a content ranging from 0 to 50%.
In another preferred embodiment, the production process comprises the steps of:
(a) adhering the copolymer with a pelletized vegetable fiber,
(b) filling a mixture of the pelletized vegetable fiber and the copolymer resulting from step (a) into a molding vessel, and
(c) molding the mixture into an intended shape by heating the mixture to bind the vegetable fiber with the copolymer.
In another preferred embodiment, the production process comprises the steps of:
(a) forming the vegetable fiber into an intended shape,
(b) adhering the copolymer with the vegetable fiber, and
(c) molding a mixture of the vegetable fiber and the copolymer resulting from step (b) by heating the mixture to bind the vegetable fiber with the copolymer.
In another preferred embodiment of the present invention, the mixing or adhering step includes a step of sprinkling powder of the copolymer onto a vegetable fiber impregnated with an organic solvent to allow the copolymer to adhere onto the fiber. Otherwise, the mixing or adhering step includes a step of spraying a solution of the copolymer in an organic solvent onto the vegetable fiber followed by drying to allow the copolymer to adhere onto the fiber.
In a preferred embodiment, the molding step includes the steps of filling the mixture of the copolymer and the vegetable fiber into a molding vessel, and heating the mixture to bind the vegetable fiber with the copolymer.
The molding step preferably comprises softening or melting the copolymer by heating. The heating is preferably conducted by irradiation of an electromagnetic wave.
The present invention also provides a method of recovering at least one of the vegetable fiber, saccharide, and aliphatic dicarboxylic acid from the cushioning molded product by treating the cushioning molded product with at least one of an acid, an alkali, high-temperature high-pressure water, and an enzyme.
The present invention also provides a cushioning molded product comprising a vegetable fiber as a main constituent, and a copolymer of a saccharide and an aliphatic dicarboxylic acid as a binder, wherein at least one of the vegetable fiber, the saccharide, the aliphatic dicarboxylic acid is a product recovered by the aforementioned recovery method.
The present invention further provides a package packed by use of the cushioning molded product, a wrapped matter wrapped by use of the cushioning molded product, and a sound absorption material and building material employing the cushioning molded product.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The inventors of the present invention disclosed a compatible complex composed of a polyester containing a saccharide in the main chain and cellulose (Japanese Patent Application Laid-Open No. 2000-313702), and a biodegradable adhesive employing a polyester containing a saccharide in th
Kikuchi Yoshihiko
Mihara Chieko
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