JPS58104721A - Preparation of synthetic resin sheet for molding container - Google Patents

Abstract

PURPOSE:To obtain a synthetic resin sheet suitable for preparation of a container by a method wherein synthetic resin with melt tension of 0.5-3.0g is co- extruded with low or medium density polyethylene resin or its copolymer to make a multilayer composite sheet. CONSTITUTION:Synthetic resin having melt tension 0.5-3.0g such as straight chain low density polyethylene, polypolyplene, high density polyethylene, etc. is co-extruded by a T-die with low or medium density polyethylene resin or its copolymer, such as ethylene vinyl acetate copolymer, ionomer, ethylene acrylic acid copolymer, ethylene-acrylate, copolymer, etc. to form a multilayer composite sheet. Thus, it is possible to obtain a container forming synthetic resin sheet which has a good moldability for the container and excellent properties.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a synthetic resin sheet for container manufacturing, and its purpose is to provide a method for manufacturing a multilayer composite sheet suitable for manufacturing containers, especially containers by vacuum forming. be.

For example, it is well known that synthetic resins are molded into so-called packaging containers, such as bottle-shaped or cup-shaped containers, which are filled with liquid foods, medicines, and similar articles by various molding methods. In this case, the resin used is selected and used as appropriate depending on the properties of the contents, but those with a single layer structure are suitable for the inner surface, that is, the conditions in contact with the contents, and the outer surface and the container. It is difficult to obtain a product that satisfies all the various physical properties and conditions that are required as a whole. In addition, even if the resin itself meets the conditions for the contents, if it is necessary to drawdown and mold from the container as described above, i.e., a sheet-shaped material, the step before forming it into a sheet is necessary. However, there is a problem in that extrusion molding cannot be performed using the T-die method due to high flowability when heated.

For example, linear low density polyethylene, Lines*r
Low Dens Port #ethyjex (hereinafter simply referred to as LLDPR).

Polypropylene, high-density polyethylene, etc. all have melt tension (MT
) is small, and LLDPB in particular has various excellent round properties as a material for containers for filling the contents as mentioned above.
There is a drawback that extrusion molding using a die cannot be performed, and therefore container forming means such as vacuum forming cannot be applied.

As a result of extensive research, the present invention has solved these problems, and has made it possible to easily manufacture containers using the resin described above, which has low melt tension, but has excellent properties when closing containers. I made it to 10″e6ru.

That is, in the present invention, the melt tension is 0.5 to 3.0I.
Container molding sheet and eggplant using synthetic resin
A method for forming synthetic resin sheets for container molding, in which low-density or medium-density polyethylene resins or their O copolymers are co-extruded to form a multilayer composite sheet (by co-extrusion using a T-die). be.

As mentioned above, the synthetic resins having a melt tension of 0.5 to 3 and an OI used in the present invention include LLDPI, polypropylene, and high-strength polyethylene.
I is preferred. These synthetic resins have excellent heat resistance, stress crack resistance, and pinhole resistance properties, and are particularly suitable for forming containers by drawdown such as vacuum forming and blow molding. .

On the other hand, low 1 is co-extruded at the same time! Degree or high 9! Polyethylene and its derivatives, such as ethylene-vinyl acetate copolymer, ionomer, ethylene-acrylic acid copolymer, and ethylene-acrylate copolymer, all have high melt tension (1,0 to 50 g) and lead. It is.

These different resins are co-extruded by co-extrusion means and extruded from a T-die to a melt tension of 5 to 3 degrees.
The former, which has a high flowability and is very hot, is immediately supported by the resin surface of the latter, which has a high melt tension and good extrusion film forming properties, and is extruded in close proximity to it, and a composite sheet is formed integrally therewith. Ru.

Usually the layer thickness is 50 to 200μlit,
Processing temperature: 200: extruded before and after and immediately obtained by -to extrusion without the need to apply any adhesive layer**. - In addition, the said melt tension is the tension at nozzle width 2-9, outflow rate o, a2g/m (MI), take-up speed 1L1 sea bream/residual air gap 450-, which is indicated by I.

The nine sheets thus obtained were formed by vacuum forming], L
It can be easily molded into a container with the LDPE side as the inner surface.

And the molded 1! The inner surface in contact with the contents has excellent heat resistance and stress crack resistance, and has a round property, making it suitable for use in detergent containers or various contents that are filled at high temperatures. It is effective for sleeping well. Since a resin layer with high melt tension is integrally formed on the front outer surface, it has good moldability as a container, and the advantages of the resin on both the inner and outer surfaces are utilized to make it easier to mold.
The present invention is extremely effective as it can be applied to the process from sheet manufacturing to continuous container molding.

Example LLDPE (MT=1.0, MI=2.1) LDP
) 3 (MT=lO, MI=1.5) Using the above resin, co-extrude with a 65 x 50 extruder and a 1000% width T-die with plLLDPE on the top and LDPK on the bottom under the following conditions. A composite sheet with a thickness of 1000 μm was formed by coextrusion. At this time, the LLDPI did not flow down (it was held on the LDPK surface, and at the same time it was integrated in a layered manner to form a composite sheet.

The resulting sheet was vacuum formed into a container with the LLDPE side as the inner surface. The moldability was good and the container properties were as shown in the table below.

Claims (1)

[Claims] In order to make a sheet for container molding using a synthetic resin with a melt tension of 0.5 to 3.011, low density or medium density polyethylene resin or their A method for producing a synthetic resin sheet for molding, which involves extruding derivatives together and forming a multilayer composite sheet.