Conventionally, for integrally forming a resin molded container with a label, a blank or a label is previously inserted into a die, and then the container is formed in the die by injection molding, blow molding, differential pressure molding, expansion molding or the like followed by decoration on the container (see, JP-A-58-69015 and Europe Patent Publication No. 254923). Such known labels for in-mold formation include resin films with gravure printing, artificial paper with multiple-colored offset printing (for example, see JP-B-2-7814 and JP-A-2-84319), or aluminum labels produced by laminating high pressure low density polyethylene, ethylene-vinyl acetate copolymer on the rear face of an aluminum foil followed by gravure printing on its front face, and the like which have already been put to practical use.
In recent years, environmental issues are growing into a serious problem as typified by Containers Recycling Law, and thus, so-called material recycle has prevailed in which plastic containers that were conventionally subjected to incineration or land filling are recovered, ground, melted and molded. By using the same material as that of the container or a thermoplastic resin having a melting point approximately that of the material of the container as a material of the label attached to the plastic container, grinding of the container can be performed in the state where the label remains attached, followed by melting and formation.
However, these labels are generally printed on the surface thereof with printing ink, thereby raising problems involved in coloring of the processed product upon melting and forming of the ground container and label. Therefore, easy delamination of the printed label from the container has been strongly desired. In this respect, JP-T-7-507397 (the term “JP-T” as used herein means a published Japanese translation of a PCT patent Application) and JP-A-10-258476 describe a label that can be delaminated; however, it was hardly adequate in terms of delamination initiation property and delamination transmission property.
Moreover, procedures of making multi-layered labels printed on respective front and rear faces, and subjecting them to temporary attachment, have been put to practical use for the purpose of describing more information on less area on the label, in recent years. However, in instances of the in-mold formation, temporary attachment between the multi-layered labels is not resistant to mold shrinkage during the molding, leading to delamination between the labels to result in lifting.
The invention solves these problems in the conventional art, and an object of the invention is to provide a label for in-mold formation which can be readily delaminated from the container by any one on behalf of excellent delamination initiation property and delamination transmission property as well as low interlaminar strength, and which can be recorded with information such as pictures and letters on the inner side concealed by the label, and therefore, enabling effective utilization of the display area, or utilization of the delaminmated label portion as a request form or a discount ticket, so called coupon.