JPS58187444A - Resin composition for sheet - Google Patents

Abstract

PURPOSE:The titled composition, prepared by kneading a paraffin wax with a straight chain low-pressure polymerized polyethylene and polyisobutylene, and having both the properties of a plastic and high-ridigity plastic and an elastic and soft rubber. CONSTITUTION:A resin composition prepared by kneading (A) 15-60wt% 20- 40C paraffin wax having 330-600 molecular weight and 50-100 deg.C melting point with (B) 10-40wt% mainly straight chain low-pressure (<=50kg/cm<2>.G) polymerized polyethylene and (C) 30-60wt% polyisobutylene, consisting of isobutylene and 10wt% or less isoprene, and having 300,000-1,000,000 viscosity-average molecular weight. The magnitude of the stress can be adjusted by changing the ratio between the components (C) and (B), and the elongation can be adjusted by increasing or reducing the amount of the component (A).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a resin composition for sheets that has both rubber and plastic properties. More specifically, the present invention relates to a resin composition for sheets that has unique mechanical properties that have the properties of both an inherently plastic and highly rigid plastic and an elastic and soft rubber.

BACKGROUND ART In recent years, it has become common practice to use films that have adhesive properties and can be easily stretched by hand to package foods and the like.

As a technology that has been proposed in this field, JP-A No. 5
1-122153 with 30-50% by weight of polyimbutylene
, 5-15% by weight of low density polyethylene.

30-65% by weight of paraffin wax (less than about 11% by weight of isoparaffin) is stated. However, the mixing of low-density polyethylene, polyisobutylene, and paraffin wax is extremely difficult to mix, and the transparency of the sheet after mixing is poor. Similarly, the transparency of the sheet during cold stretching is also poor. .

The present inventors: (1) The film is soft and can be lightly cold stretched.

(2) The film has no tackiness and has tackiness during cold stretching.

(3) Excellent transparency.

As a result of intensive research to achieve this, paraffin wax 15
~60% by weight, mainly linear low-pressure polymerization, l-”IJ
Ethylene 10-40% by weight, polyisobutylene 30-6%
A resin composition for sheets mainly containing 0% by weight.

invented.

The low-pressure polymerized polyethylene in the present invention refers to polyethylene that is polymerized at a pressure of 50 ky'/cm2G or less during polymerization, and includes a Ti-At-based or V-based catalyst system, or a Ziegler jujube system in which these are supported on a magnesium compound. It is synthesized using a catalyst. Polyethylene produced by these methods generally has higher crystallinity and therefore higher density than low-density polyethylene produced by a high-pressure method using a small amount of oxygen as a catalyst.

Its molecular structure is characterized by a straight chain with little branching in the main chain.

In addition, the low-pressure polymerized polyethylene of the present invention includes a copolymer of ethylene and α-olefin, that is, propylene, 1
-butene, 1-pentene, 4-methyl-1-pentene,
Copolymers with 1-hexene, 1-hephtene, 1-octene, ■-decene, ■-dodecene, 1-tetradecene, etc. are included, and therefore, of course, so-called linear low-density polyethylene (L-LDPE) Also included in the low-pressure polymerized polyethylene of the present invention.

The paraffin wax in the present invention includes normal paraffin and isoparaffin, so it usually has about 20 to 40 carbon atoms, a molecular weight of 300 to 600, a melting point of 50 to 100°C, Preferably it is about 55 to 75°C.

Although JP-A-51-122153 restricts the content of isoparaffin, according to the present invention, such restrictions are not necessarily necessary, and a wide range of paraffin waxes can be used.

Polyisobutylene in the present invention is a polymer consisting of inbutylene and 10% or less of isoprene, and has a viscosity average molecular weight of about 300,000 to 1,000,000.

The resin composition for sheets of the present invention is obtained by kneading the paraffin wax, linear low-pressure polymerized polyethylene, and polyinobutylene described above in a known mixer such as a kneader, Banbury mixer, or Henschel mixer. The mixing ratio of each component of the composition is determined so that the magnitude of stress and elongation are within the desired range, and the former is determined by changing the ratio of polyimbutylene/low-pressure polymerized polyethylene, and the latter is determined by changing the ratio of polyimbutylene/low-pressure polymerized polyethylene. , adjusted by increasing or decreasing the amount of paraffin wax.

In other words, taking these into account, paraffin wax is
The content may be appropriately selected within the range of 5 to 60% by weight, 10 to 40% by weight of low-pressure polymerized polyethylene, and 30 to 60% by weight of polyisobutylene.

In addition, the composition of the present invention obtained by the usual crosstalk method is
It can be formed into a sorted shape by a known method such as a calendar method or an extrusion method.

The present invention will be explained below with reference to Examples.

(Example) (Polyisobutylene (R) with a viscosity average molecular weight of about 400,000
-1) and about 1 million polyimbutylene (
R-2), (ii) Linear low-pressure polymerized polyethylene, (
Paraffin wax at point iii + a at about 6 oC
The compositions were blended in the composition ratios shown in the table and kneaded using an oven roll V. This kneaded material was extruded onto a metal surface through a T-die at a temperature of about 180°C using a single-screw extruder to obtain sheets A, B, ..., H of about 100 μm. Table 2 shows the results of measuring , blocking property, and haze.

(Comparative Example) A film 1. was obtained in the same manner as in the example with the composition ratios shown in Table 1. Table 2 shows the results of similar measurements for J and K.

Table 2 e 1) Elongation at break at tensile speed 200w1L/mi.

700X or more is desirable 4 2) 400XIl'j [at 3) for glass
None ・・・・・・・・・0 Somewhat happens・・・・・・・・・ △ A lot ・・・・・・・・・・・・×4) 400
% in the stretched state according to ASTM D-1003.

As is clear from the pass table of 50% or more, the composition of the present invention exhibits good properties in terms of elongation, tackiness, prosokinkability, and especially haze (transparency).

The composition of the present invention has greatly improved mixing workability compared to the conventionally proposed case of using high-pressure polymerized low-density polyethylene.

patent applicant Mitsui Toatsu Chemical Co., Ltd.

Claims (1)

[Claims] (1) 15-60% by weight of paraffin wax, 710-40% by weight of mainly linear low-pressure polymerized polyethylene,
A resin composition for sheets mainly containing 30 to 60% by weight of polyisobutylene.