JPH01168751A - Easily processable shape memory composition - Google Patents

Abstract

PURPOSE:To obtain the title composition improved in shape memory characteristics and processability, by mixing a polynorbornene with a PE resin. CONSTITUTION:100 pts.wt. mixture of 90-40 pts.wt. polynorbornene of a true specific gravity of about 0.65, a glass transition point of about 35 deg.C, an average MW >=2000000 and a particle diameter of 0.3-0.4mm with 10-60 pts.wt. PE resin of an MI of 0.1-20g/10min is optionally mixed with an antioxidant, a lubricant, a filler, a colorant, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a polymer composition with excellent processability that can be deformed and used and then restored to its original shape by heating.

<Prior art> Polynorbornene is a polymer obtained by ring-opening polymerization of norbornene, and its glass transition point is 35°C, which is slightly higher than room temperature. It is known that after being used after being appropriately deformed at room temperature, it can be restored to its original shape by heating it to a temperature above the glass transition point, for example, 40°C. As for the molding method, since the weight average molecular weight of polynorbornene is extremely high at approximately 2 million or more, it is difficult to mold it by conventional plastic molding methods such as extrusion, injection molding, and calendering, so compression molding is applied. .

<Problems to be solved by the invention> The compression molding method has low molding efficiency, and as an improvement method, a rubber additive with a special composition is used, a thick sheet is produced by calendering, and this is pressed to form a plate. However, it is difficult to form thin sheets, and the product has a poor texture. In injection molding, the viscosity increases due to the decomposition of the rubber additive and the crosslinking reaction, making it impossible to obtain a satisfactory product. Furthermore, manufacturing costs are high, which has delayed the development of products that take advantage of the long-awaited shape memory properties.

<Means for solving the problem> The inventors searched for a composition with excellent processability without impairing the shape memory properties of polynorbornene, and found that the processability was improved by mixing polyethylene in a specific range. The present invention has been completed based on the discovery that this can be improved.

Thus, according to the invention, polynorbornene 90-4
0iiffi part and polyethylene thermoplastic resin 10-6
Provided is an easily processable shape memory composition containing 0 parts by weight.

As the polynorbornene used in the present invention, for example, one manufactured by CdF Chime can be used, which has an average molecular weight of 1i2 million or more and a true specific gravity of 0.96. Glass transition point 35℃2 particle size 0.3
~0.4mm white powder.

The polyethylene resin blended with polynorbornene may be either high-density polyethylene or low-density polyethylene, or may be a mixture of polyethylene and chlorinated polyethylene or chlorinated polyethylene alone.

The above-mentioned polyethylene resin needs to have good fluidity when melted, and the desirable range of the melt index is 0.1 to 20 g/10w1n.

The blending ratio of the above polynorbornene and polyethylene resin is 90 to 4 polynorbornene per 100 weight groups of the mixture.
If the polyethylene resin is less than 10 parts by weight and 10 to 60 parts by weight of the polyethylene resin mixture, the processability will be poor, and if it exceeds 60 MIk parts, the shape memory will be deteriorated.

Antioxidants, lubricants, fillers, coloring agents, etc. commonly used in resin processing are appropriately added to the above mixture in order to improve moldability, impart rigidity to the product, and the like.

As a molding method, ordinary plastic molding methods such as a method of molding the above-mentioned mixture into a sheet shape by calendering, a method of powder blending and extrusion molding, a method of pelletizing and injection molding are applied.

Next, in the present invention, the following evaluation method was used for shape memory properties. That is, a test piece of II@5 and length 901 was cut out from the molded sheet with a thickness of 11, and this was cut into a length of 200 in the longitudinal direction, with the original length being 100 at room temperature, i.e. 200. %, and measure the length of each stretched product by immersing it in warm water at 40°C, 50°C, and 60°C, and when the length returns to 130%, for example, it is displayed as 30% remaining, Remaining rate 30% or less at 40℃,
15% or less residual rate at 50℃, 10% residual rate at 60℃
The following cases were evaluated as having good shape restorability.

It is considered that a product with a residual rate equal to or lower than the above at each temperature has sufficient shape memory for practical purposes.

<Examples> The present invention will be explained in more detail below using Examples.

Example 1 Made from polynorbornene (CdF?, France), trade name Norflex 2, polymerization degree of 2 million or more, particle size 0.3 to 0.4 nu
++), polyethylene with a melt index of 0.5 was used, and the compositions were blended according to the following Table 1.

Table l The above formulation was kneaded with a roll at about 150°C for 20 minutes,
A sheet with a thickness of 1 mm was obtained. 5mm x 9 from this sheet
A 0 mm test piece was prepared, and a shape memory recovery experiment was conducted according to the method described above.

For comparison, a test piece containing 30 parts by weight of polynorbornene and 70 parts by weight of polyethylene was prepared in exactly the same manner as in Example 1, and a shape memory recovery experiment was conducted in the same manner. The results are shown in Table 2 below.

Table 2 From the results, it can be seen that the test pieces of Examples have good shape memory recovery properties, while the comparative test pieces have very poor shape memory recovery properties. 'Example 2 A test piece was prepared in exactly the same manner as in Example 1, except that polyethylene having a melt index of 15 was used, and an experiment on shape memory recovery was conducted.

The results were almost the same as those shown in Table 2.

Example 3 The sheet obtained in Example 1 was pelletized using a pelletizer,
The pellets were used to mold the body of a doll at about 200° C. using an injection molding machine.

The molded product had good moldability and an extremely good appearance including gloss.

For comparison, injection molding was also carried out using only polynorbornene, but injection molding was extremely difficult.

<Effects of the invention> By using the composition of the present invention, processability is improved,
It has become possible to apply various molding methods, and for example, conventionally sheets could only be obtained with a thickness of 0.7 mm or more, but now it is possible to extrude sheets as thin as 0.1 mm. Examples of applications include using it as origami, heating it to return it to its original state, or extruding it into an AIW shape and curling or stretching it as doll hair.In addition to using it as a toy, it can also be used as a shape memory for stationery, daily necessities, etc. We are looking forward to a wide range of applications that take advantage of its gender.

Patent applicant: Zeon Kasei Co., Ltd.

Claims (1)

[Claims] 1. An easily processable shape memory composition containing 90 to 40 parts by weight of polynorbornene and 10 to 60 parts by weight of a polyethylene resin.