JPS591305B2 - Composition for lacquerware base - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composition for a lacquerware base that has good paintability and moldability.

More specifically, the present invention relates to a lacquerware base composition comprising polypropylene, calcium carbonate, dry wood flour, and atactic polypropylene. Traditionally, lacquerware such as trays, bowls, sets, jubako, tea cups, and other kitchen and dining utensils have been made of wood as their base material, but in recent years, phenolic resin and melamine have been used for reasons of mass production and cost. Thermosetting resins such as resins and urea resins, and thermoplastic resins such as nylon resins and ABS resins have come to be used to some extent in place of wood.

However, phenolic resins and melamine resins generally have low mechanical strength such as impact strength, making it difficult to mass-produce them, and urea resins have health and hygiene problems due to the generation of formaldehyde when handled, as well as damage and damage. It has the disadvantage of being easily deformed. In addition, nylon resin and ABS resin are easily deformed by heat due to hot water, etc., and are also difficult in terms of price, and these synthetic resins have not yet reached the point where they can fully replace wood as a base for lacquerware. Moreover, some of these synthetic resin materials have the disadvantage that they may generate harmful gases when incinerated during disposal. Furthermore, when these synthetic resin materials are used, deburring after molding is not easy.

In other words, in the case of thermosetting resins, deburring is done with sandpaper after molding, but this is a difficult task, and in the case of thermoplastic resins, deburring is done with sandpaper. If this is done, the surface of the molded body may become roughened or the surface of the molded body may be deformed due to frictional heat, so it cannot be used, and therefore it is decided to deburr with a knife. However, this method alone has the disadvantage that it is difficult to obtain a smooth surface. Here, the present inventors have improved the drawbacks of various synthetic resins used as lacquerware bases in the past, and have found that they have good paintability and moldability, are mass-producible, are inexpensive, and have sufficient properties as lacquerware bases. After searching and studying various synthetic resin materials with physical properties, we found that polypropylene is 30 to 60% by weight, calcium carbonate is 30 to 50% by weight, and dry wood flour is 10 to 30% by weight.
It has been found that a composition comprising 3 to 5% by weight of atactic polypropylene is most suitable as a lacquerware base.

In addition, when the composition according to the present invention is used as a lacquerware base, deburring after molding can be done extremely easily using sandpaper, and as in the case of conventional wood bases, deburring can be carried out extremely easily. There is no need to perform rusting work on the base by using a similar method, and work efficiency is significantly improved.

It has been found that when polypropylene is used alone as a lacquerware base, the rigidity, surface hardness, and adhesion strength of paint are significantly inferior to those of wood materials. To improve this, calcium carbonate was added to polypropylene in the hope of improving its rigidity and surface hardness, and wood flour was added in the hope of improving paintability.
It has been found that these have good affinity with polypropylene, and within the range of the above-mentioned mixing ratio, exhibit extremely suitable physical properties as a lacquerware base. However, it has been found that, depending on the shape of the lacquerware, if it is necessary to improve its moldability, it is necessary to further add attic polypropylene to the above composition. Atactic polypropylene seems to have the effect of increasing the fluidity of the composition of the present invention when melted. When the amount of atactic polypropylene added is 3% by weight or less in the entire composition, the injection pressure during injection molding is high;
Depending on the shape of the product, moldability may be poor, silver marks may appear, and paintability may be poor. The polypropylene used in the present invention includes not only commercially available general products but also copolymers containing propylene as a main component with ethylene or the like.

Calcium carbonate is 100 to 250 mesh,
Wood flour is made by drying cedar, birch, etc. in addition to sharp maple, and has a moisture content of about 5 to 7% by weight, with a mesh size of 80 to 200. Atactic polypropylene has a molecular weight of 25,000. Those having a molecular weight of about 35,000 to 35,000 are suitable as components of the composition of the present invention. A particularly suitable mixing ratio for the composition for lacquerware base of the present invention is polypropylene 40 to 45
% by weight, 35-40% by weight of calcium carbonate, 15-20% by weight of dry wood flour, 3-5% by weight of atactic polypropylene.

Increasing the amount of calcium carbonate or dry wood flour used is advantageous in terms of cost, but it is also undesirable because it may lead to poor moldability and reduce the impact strength of the product. The composition of the present invention is prepared by kneading the above mixture at 180 to 200°C for about 1 minute using a kneader, and then forming it into pellets using an extruder and a pelletizer. Lacquerware bases of arbitrary shapes can be obtained by injection molding at temperatures around ℃.

It goes without saying that the formed lacquerware base can be used as is or used as various containers, but for a paint finish, it must first be coated with an undercoat material such as polyurethane, and then coated with epoxy or polyurethane paint. Lacquerware products are finished by applying natural lacquer or other materials. Next, the present invention will be explained in more detail with reference to Examples.

Examples 1-2 As polypropylene, pellets of WlOl manufactured by Sumitomo Chemical Co., Ltd., 200 meshes of calcium carbonate powder, 100 meshes of dry wood powder obtained from the woody part of Toga, and pellets of atactic polypropylene with a molecular weight of 25,000 were used. This is melt-kneaded at 200° C. for 1 minute using an FCM Farrel type continuous kneader manufactured by Kobe Steel, Ltd., and then passed through an extruder and pelletized using a pelletizer.

Claims (1)

[Claims] 1 30 to 60% by weight of polypropylene, 30 to 50% by weight of calcium carbonate, 10 to 30% by weight of dry wood flour
% by weight, atactic polypropylene 3 to 5% by weight
A composition for lacquerware base consisting of.