JPS63248834A - Production of releasing material - Google Patents

Abstract

PURPOSE:To obtain the titled material having excellent release properties and good writing properties of marking ink, by molding a composition consisting of polyolefin based thermoplastic polymer and a specific release agent, subjecting the release agent to breeding on the surface of moldings and irradiating the moldings with electron beam. CONSTITUTION:A composition consisting of (A) polyolefin based thermoplastic polymer and (B) dimethylpolysiloxane is molded e.g. by an extruding lamination method, etc. Then the component B is subjected to bleeding on the surface of the moldings and the treated moldings are the irradiated with electron beam preferably at an irradiation amount of 5-10 Mrad to provide the aimed mate rial. As the component A, a mixture of low density polyethylene and polypropylene is preferably used. As the component B, dimethylpolysiloxane blocked with terminal trimethylsilyl groups or terminal hydroxydimethylsilyl groups is preferably used.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention mainly relates to a method for manufacturing release paper, etc. that imparts releasability to the base surface of patches, stickers, etc., or the back surface of wound packaging tape, etc. .

[Conventional technology]

Conventionally, release paper used as the base of adhesive sheets for patches, stickers, etc., or the back side of wrapped adhesive tapes for packaging, etc., has a base material surface laminated with polyolefin in order to exhibit releasability. On top of this, expensive reactive silicone was applied and a heat curing process was performed. The process consists of coating, drying, and crosslinking silicone, and the length of the equipment used for this process is usually several tens of meters, making it large-scale. Furthermore, since solvents such as toluene are used when applying reactive silicones,
Its recovery also requires a large amount of equipment cost and energy.

[Problem that the invention seeks to solve]

If a release paper with good performance can be produced by mixing the silicone oil with a thermoplastic resin, the large-scale process described above can be omitted.

However, in this case, the releasability required for release paper is not achieved, and the silicone oil that bleeds onto the surface transfers to the adhesive layer of patches, stickers, etc., reducing its adhesive strength. This is a fatal flaw as a seal.

As a method to solve this problem,
No. 21 proposes a method in which a radiation-curable organopolysiloxane is added and mixed with a resin, molded by lamination and inflation methods, and then irradiated with radiation. If siloxane is not used, practical performance will not be achieved.

[Means for solving problems]

The present inventors took into consideration the problems with the current method described above, and as a result of intensive studies to develop an inexpensive method for producing removable materials that does not require complicated processes, A composition consisting of chemically stable dimethylpolysiloxane and &IJ olefin-based thermoplastic resin, which is difficult to cure only by heating, is molded, and after the dimethylpolysiloxane is bled onto the surface of the molded product, it is By applying radiation irradiation, excellent peeling performance (low peel strength and high residual adhesive rate) is developed, and there is no transfer to the adhesive.
Even more surprisingly, despite its high peeling performance,
It was discovered that the marker ink has good writing properties.

The present invention was made based on the discovery that it is possible to use dimethylpolysiloxane, which does not have functional groups, as a stripping agent, and which has had extremely poor reactivity and has been difficult to exhibit performance.

[Specific structure and operation of the invention]

The present invention will be explained in detail below.

Polyolefin thermoplastic resins used as raw materials in the present invention include high-density polyethylene, medium-density polyethylene, low-density polyethylene, polypropylene, copolymers mainly composed of these, ethylene and vinyl esters, or α,β-unsaturated carpons. Copolymers with acid esters, etc. can be used.

Preferably, ethylene polymer, ethylene-propylene copolymer, ethylene-butene copolymer, polypropylene,
Polybutene and poly-4-methyl-1-pentene can be used. These can exhibit performance even when used alone, but performance can be easily achieved by using a mixture of two or more specific types. In this case, polyethylene and C3~
It is preferable to use a mixture containing a C5 α-olefin homopolymer or copolymer as an essential component. Among these, it is suitable to use a mixture of low density polyethylene and polypropylene. Its composition ratio is polyethylene 1~
99 weight factor to polypropylene 99-1 weight factor,
Preferably, for polyethylene from 10 weight ratio or more to 40 weight ratio or less, polypropylene is 90 weight ratio or less to 60 weight ratio on a board, and for polyethylene from 90 weight ratio or less to 60 weight ratio or more, polynolopylene is 10 weight ratio or more to 40 weight ratio or less, more preferably polypropylene 85-7 to polyethylene 15-30 weight ratio
Polypropylene has a weight ratio of 15 to 30 compared to 0 weight ratio and polyethylene 85 to 0 weight ratio. If polyethylene is more than 40% by weight and less than 60% by weight, polypropylene is less than 60% by weight and more than 40% by weight,
Although there is no problem in terms of performance, moldability becomes significantly worse.

The melt index or melt flow rate of polyolefin thermoplastic resin is generally 0.01 to 2.
0011/ 10m1n, 0.1~100! i/
10 m1n is desirable, and 1 to 201/10 min is suitable.

In addition, the melt index of a mixture of low density polyethylene and polypropylene, which is the composition that most easily exhibits performance, is 0.01 to 200 for polyethylene.
Fi/ 10m1n, 0.1~100.9/10
m1n is desirable, 0.5 to 15,! i'/10m
1n is preferable, and as polypropylene, 0.01
~150.9/10m1n, 1~100! /
10 m1n is desirable, and 2 to 301/10 m1n is suitable.

In addition, the dimethylpolysiloxane to be mixed with the polyolefin thermoplastic resin has a terminal of 15iR1R2R3.
(However, R1, n2, and R3 are each independently selected from a methyl group, a hydroxyl group, and a C-C3 alkoxy group). Preferably, it is a dimethylpolysiloxane with trimethylsilyl groups blocked at both ends and hydroxydimethylsilyl groups blocked at both ends. Viscosity at 25℃ is 50~8 x 1060s
In particular, those in the range of 500 to 60.0 OOcs are preferred. If the viscosity at 25°C is lower than 500 s, it is difficult to mix with the thermoplastic resin and difficult to mold, and a large irradiation dose is required to develop sufficient peeling performance, resulting in the formation of a matrix. Significantly reduces the mechanical strength of the resin. Moreover, if it exceeds 8×10 cs, it becomes difficult to exhibit sufficient peeling performance.

In addition, the mixing ratio of dimethylpolysiloxane with the polyolefin thermoplastic resin is 0.5 to 30 parts by weight, preferably 1 to 15 parts by weight, and preferably 2 to 6 parts by weight. It is. The amount is 0.
If it is less than 5% by weight, sufficient peeling performance cannot be obtained, and 30%
If the weight ratio is exceeded, it becomes difficult to mix dimethylpolysiloxane, making molding extremely difficult, or it is disadvantageous in terms of cost.

In order to mix the above polyolefin thermoplastic resin and dimethylpolysiloxane, it is generally necessary to cross-wire the synthetic resin,
Equipment used for mixing can be used. For example, Banbury mixer, kneader 1 twin screw extruder, single screw extruder,
There is a method of melting and mixing using a mixer such as a roll mill. In particular, when dimethylpolysiloxane with low viscosity is used, ordinary mixing becomes difficult, so dimethylpolysiloxane is mixed by injecting it into the middle of the cylinder of the extruder with a pump.

To mold the above mixture, a conventional extrusion lamination method, a coextrusion lamination method, an inflation method, or a coextrusion inflation method may be selected depending on the purpose and use. A releasable surface can be formed by subjecting this molded article to electron beam irradiation treatment.

The method for bleeding the added and mixed dimethylpolysiloxane onto the surface after molding varies depending on the resin composition of the matrix, the viscosity of the dimethylpolysiloxane, and the amount of dimethylpolysiloxane added. In many cases, it bleeds completely immediately after molding, but it can be aged if necessary. When aging, the temperature may be applied to a level that does not cause deformation, or it may be at room temperature.

In relation to dimethylpolysiloxanes, lower viscosities are advantageous.

Methods for carrying out the above electron beam treatment include Kotsukucroft type, Kotskucroft Walton type, bumpgraph type,
Methods include emitting electron beams from various types of electron beam accelerators, such as insulated core transformer type, linear type, dynamidron star, high frequency type, and electron curtain type. The irradiation dose can vary within a wide range depending on the required performance of the irradiated object. Generally, it is less than 30 megarads, 1~
A value of 15 megarads is desirable, and a range of 5 to 10 megarads is preferred. If the irradiation dose exceeds 30 megarads, the mechanical strength of the matrix polymer will be extremely low, making it impractical. Also, the acceleration voltage is not particularly particular, but it is 100~
300kV is practical.

The atmosphere during irradiation is preferably an inert gas. Representative examples of this inert gas include nitrogen, carbon dioxide, helium, and the like.

The mechanism by which the system of the present invention exhibits excellent peeling performance by irradiating it with an electron beam is not necessarily clear. However, when a polyolefin thermoplastic resin that has the property of crosslinking or decomposing with electron beams coexists with dimethylpolysiloxane, the radicals generated in the polyolefin and the dimethylpolysiloxane radicals interact delicately and complexly, resulting in graft reactions and/or Alternatively, it is thought that it promotes crosslinking between siloxanes, leading to special performance.

The method of the present invention does not require conventional large-scale coating, drying, crosslinking, or solvent recovery steps, and can be realized by changing and combining the mixing ratio of dimethylpolysiloxane used, electron beam treatment conditions, etc. The peeling performance can be adjusted.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples; however, the present invention is not limited to these examples as long as the gist thereof is not exceeded.

In Examples and Comparative Examples, the peel strength and residual adhesion of samples prepared under various conditions were measured, and the results are summarized in Table 1.

The peel strength and residual adhesion rate described above were measured as follows. That is, using Byron Craft Chee F (manufactured by Kyowa Co., Ltd.) as a standard tape, it was pasted on the laminated surface of release paper, a 180° peel test was conducted in accordance with JIS-Z-0237, and further JIS-Z-0237 was applied. Z-15
The residual adhesion rate was measured according to No. 23.

Example 1 Melt flow rate (hereinafter abbreviated as MFR) is 20g/1
0 mtl of polyzolopyrene (Rainbow Aroma manufactured by Showa Denko K.K.) (hereinafter abbreviated as PP) and melt index (
Low-density polyethylene (Nijiyo Rex manufactured by Showa Denko (Same)) (hereinafter abbreviated as LD) with a density of 0.925 and a PP/LD = 8
2 to the melt-mixed mixture at a ratio of 0/2o (wt%).
Dimethylpolysiloxane (manufactured by Toshi Silicone Co., Ltd.: 5H200) with a viscosity of 500 cs at 5°C (hereinafter P
DMS-1) was extruded and laminated onto kraft paper laminated with polypropylene at a resin temperature of 315°C and a lamination thickness of 10 μm, followed by an oxygen concentration of 300 ppm and a line speed of 30.
Electron beam irradiation treatment was performed at m/min and an irradiation dose of 6 megarads. The results are shown in Table 1.

Example 2 In extrusion lamination on kraft paper laminated with polypropylene, no dimethylsiloxane was added to the kraft paper p p (MFR = 30f!7
The same test as in Example 1 was conducted, except that the mixture of Example 1 (10 m1n) and the mixture of Example 1 were coextruded and laminated (resin @ 315°C, lamination thickness of 10 μm).

The results are shown in Table 1.

Example 3 In Example 1, the mixing ratio of pp and LD was set to PP/LD=80/
Instead of 20 (wt%), PP/LD=70/30 (
The same procedure as in Example 1 was carried out except that % by weight was used. The complete results are shown in Table 1.

Example 4 In Example 1, the viscosity at 25°C was 3000 cs (hereinafter abbreviated as PDMS-II) instead of PDMS-1.
Example 1 was carried out in the same manner as in Example 1 except that dimethylpolysiloxane was used. The results are shown in Table 1.

Example 5 The same procedure as in Example 1 was carried out except that dimethylsiloxane having a viscosity at 25° C. of 30.0 OOc+ (hereinafter abbreviated as PDMS-III) was used instead of PDMS-1. The results are shown in Table 1.

Example 6 The same procedure as in Example 1 was conducted except that the amount of PDMS-1 added in Example 1 was changed from 3% by weight to 5% by weight. The results are shown in Table 1.

Example 7 In Example 1, the amount of electron beam irradiation was changed to 1 to 6 megarads.
The same procedure as in Example 1 was carried out except that the concentration was 0 megarad. The results are shown in Table 1.

Comparative Example 1 The same procedure as in Example 1 was conducted except that electron beam irradiation was not performed. The results are shown in Table 1.

Comparative Example 2 The same procedure as in Example 1 was conducted except that the amount of PDMS-I added to the resin mixture was 0.2% by weight. The results are shown in Table 1.

Comparative Example 3 In Example 1, when the amount of PDMS-III added to the resin mixture was set to 35 fill, it could not be extruded with an extruder when mixed with the resin mixture.

The measurement results of the peel strength and residual adhesive rate of Examples 1 to 7 and Comparative Examples 1 to 2 are shown in Table 1. Further, as a reference example, the peel strength and residual adhesive rate of Pylon Craft Tea 7'' used as a standard tape were measured in the same manner as in Example 1, and the results are also listed in Table 1.

Table 1 [Effects of the Invention] As described above, the method of the present invention has excellent peeling performance by mixing dimethylpolysiloxane with a polyolefin thermoplastic resin, molding it, and subjecting it to electron beam irradiation treatment. Not only does it provide excellent performance, but it also provides a removable surface that can be written on with marker ink. Moreover, unlike conventional methods, large-scale equipment for heat treatment or solvent recovery is not required, and a releasable surface can be easily obtained, so the economic effect is extremely large.

Claims (8)

[Claims] (1) A removable material characterized by molding a composition consisting of a polyolefin thermoplastic resin and dimethylpolysiloxane, allowing dimethylpolysiloxane to bleed onto the surface of the molded product, and then irradiating it with an electron beam. Production method. (2) The amount of dimethylpolysiloxane in the composition is 0.5
The manufacturing method according to claim 1, wherein the content is 30% by weight. (3) The polyolefin thermoplastic resin is composed of a mixture of two or more types of polyolefins, and the mixture contains polyethylene and a mono (or co)polymer of C_3 to C_5 α-olefins as essential components. 1
Manufacturing method described in section. (4) The manufacturing method according to claim 1, wherein the irradiation dose of the electron beam is 30 megarads or less. (5) The manufacturing method according to claim 1, wherein the molded product is a film. (6) Claim 1 in which the molded product is a laminated film
Manufacturing method described in section. (7) The manufacturing method according to claim 6, wherein the laminated film has a three-layer structure of paper/polyolefin/dimethylpolysiloxane-containing polyolefin. (8) The manufacturing method according to claim 3, wherein the α-olefin of C_3 to C_5 is propylene.