JPH02175777A - Thin propylene resin sheet for release paper base - Google Patents

Abstract

PURPOSE:To prepare a thin sheet with an improved heat resistance, nerve, lightweightness and dimensional stability and useful as a release paper base by forming a propylene homopolymer into a sheet and then stretching the sheet in a specified stretching ratio. CONSTITUTION:A propylene homopolymer having a melt flow index (JIS K7210) of 1.0-15g/10min, pref. 2.0-10g/10min, is formed into a sheet at 200-250 deg.C, and stretched in a stretching ratio of 1.5-7, pref. 1.5-6, to give a thin sheet with a thickness of 500-1000mum and a permanent set of 2% or lower.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin propylene resin material suitable as a base material for release paper. More specifically, the present invention relates to a thin propylene resin material that not only has good heat resistance but also has stiffness and is suitable as a base material for release paper.

[Conventional technology]

Conventionally, most of the base materials for release paper are paper.

In addition, low density polyethylene (hereinafter referred to as rLDPEJ) having long chain branches on one or both sides of the paper and linear low density polyethylene (hereinafter referred to as rLLDPEJ) having short chain branches on one or both sides of the paper are used.
A mixed resin layer consisting of LDPE or LLD
A release paper base material provided with a mixed resin layer consisting of PE and medium-density to high-density polyethylene or a mixed resin layer consisting of LDPE and polypropylene has been proposed (Utility Model Publications No. 82-23794, No. 62-23790). , Dojitsu Kosho No. 62-23791). However, release paper based solely on plastic has rarely been commercialized.

Therefore, the present inventors have previously discovered that a thin stretched foam made of a propylene homopolymer not only has excellent heat resistance but also has firmness and is therefore promising as a base material for release paper.

[Problem to be solved by the invention]

However, in the case of a paper base material, ethylene resin or the like is laminated onto the paper to make the base material for the release paper, so there are problems such as curling of the paper and occurrence of pinholes due to unevenness of the paper during lamination. Furthermore, dimensional stability due to heat is also a problem with ethylene-based resins, which can only achieve heat resistance of about 120° C. at most, and there is also a limit to the processing speed in the silicone curing process.

On the other hand, plastic has a high Young's modulus and is lightweight.

This is thought to be due to insufficient dimensional stability due to heat resistance. Also, the previously captured thin-walled stretch-foamed propylene homopolymer products are not necessarily satisfactory.

In light of the above, the object of the present invention is to obtain a thin propylene resin material that does not have these problems (defects), has excellent heat resistance, and is flexible and suitable as a release paper base material.

[Means and effects for solving the problems] According to the present invention, these problems are a thin product made of propylene homopolymer, the stretching ratio of the thin product is 1.5 to 7 times, and there is no permanent deformation. rate is at most 2%
This problem can be solved by a thin propylene resin material for release paper base material, which is as follows. The present invention will be specifically explained below.

The melt flow index of the propylene homopolymer used in the present invention (according to JIS K7210,
Measured under conditions 14, hereinafter referred to as "MFRJ" is usually 1.
0-15 g/lo min, 2.0-15 g/1
0 minutes is preferred, and 2.0 to Log/10 minutes is particularly preferred. If a propylene homopolymer with an MFR of less than 1.0 g/10 minutes is used, moldability will not be good when producing thin products. On the other hand, if the amount exceeds 15 g/10 minutes, not only the moldability is poor but also high stretching ratio cannot be achieved.

The thin-walled article of the present invention can be produced using only propylene homopolymer. In addition, additives such as stabilizers against oxygen, light (ultraviolet rays), and heat, antistatic agents, lubricants, plasticizers, and coloring agents, which are commonly used in the field of propylene resins, are added to the propylene homopolymer of the present invention. It may be added within a range that does not essentially impair the properties of the composition.

A base material for release paper can be obtained by molding the composition thus obtained into a thin shape. For thin-walled products, T is commonly used in the field of olefin resins.
It can be obtained by a molding method such as a die molding method or an inflation molding method. At this time, the molding temperature is generally 200 to 250°C (preferably 200 to 240°C). The thickness of the thin-walled product obtained in this way is usually 50~
1000! Ea (preferably 60 to 500!E@). Furthermore, the stretching ratio is 1.5 to 7 times (preferably,
1.5 to 6 times). This is because this stretching increases Young's modulus. If the stretching ratio is less than 1.5 times, a high Young's modulus cannot be achieved. On the other hand, it becomes difficult to stretch the film more than 7 times.

In addition, the permanent deformation rate (value obtained by applying a load of 30 kg in an oven for 80 seconds at a temperature of 120°C, then removing the load and dividing the amount of strain by the original length when returning to room temperature) is at most 2. %
It is important to On the other hand, if the permanent deformation rate exceeds 2%, the thin-walled product will become walnut or deformed during the curing process using silicone resin, etc., making it impossible to obtain a satisfactory thin-walled product.

In order to produce a release paper using the thin material obtained as described above, a release agent layer described later is provided on one or both sides of the thin material, but in the case where the release agent layer is provided on one side, A resin layer of polyvinylidene chloride, polystyrene, styrene-butadiene copolymer, cellulose derivative, polyolefin, or the like may be provided on the opposite thin surface.

The release agent may be one that is widely used in the field of release paper, and is not particularly limited, but typical examples include silicone resins (addition reaction type and condensation reaction type), silicone-alkyd copolymers. , alkoxide resins, and mixtures of polyvinyl alcohol and silicone resins.

In addition, in order to further strengthen the adhesion between the thin-walled article and the release agent, it is also possible to previously perform treatments such as corona discharge treatment, ultraviolet radiation treatment, and oxidation treatment on the surface of the thin-walled article.

The release paper thus obtained is used by being bonded to an adhesive sheet or adhesive tape coated with a pressure-sensitive adhesive, a heat-sensitive adhesive, a prepreg adhesive, or the like.

[Examples and comparative examples]

Hereinafter, the present invention will be explained in more detail with reference to Examples.

In the Examples and Comparative Examples, the density was determined by measuring and calculating the volume and weight of the obtained thin-walled material. Moreover, the foaming ratio was calculated from this density. Furthermore, Young's modulus was measured according to JIS K8758. Heat resistance is determined by placing a thin-walled article in an oven, leaving it for one minute, and then measuring the lowest temperature at which thermal deformation occurs.

Example I A propylene homopolymer with an MFR of 8-2 g/10 min was produced using an extruder (diameter 65 ml) at a resin temperature of 230 ml.
Sheet molding was performed at °C to produce a sheet with a thickness of 110 μs. This sheet was stretched 5 times so that the permanent deformation rate was within 2% to produce a stretched film.

Example 2 A sheet was molded in the same manner as in Example 1, and the sheet was stretched six times so that the permanent deformation rate was within 2% to produce a stretched film.

Comparative Example 1 A sheet was molded in the same manner as in Example 1, and a stretched film was produced from the obtained sheet so that the stretching ratio was 5 times. The permanent deformation rate of the obtained film was 5%.

Comparative Example 2 The mixture obtained in Example 1 was extruded at a temperature of 230°C.
An unstretched film having a thickness of 27 μs was produced using the T-die method. The permanent deformation rate of the obtained film was 9%.

The density of each film obtained in this way 1 expansion ratio,
Young's modulus and heat resistance were measured. those results first
Shown in the table.

Table 1 Note that the films obtained in Examples 1 and 2 were subjected to silicone resin curing treatment. Both films were smooth. However, in Comparative Example 1, unevenness occurred in the film.

〔Effect of the invention〕

The propylene resin thin material for release paper base material of the present invention exhibits the following effects.

(1) It has excellent heat resistance (2) It has high rigidity and therefore strong stiffness (3) It is lightweight (4) It has good dimensional stability The thin propylene resin material for release paper base material of the present invention is as follows. It is promising as a base material for release paper by coating the surface with silicon to exhibit the following effects.

Claims (1)

[Claims] It is a thin product made of propylene homopolymer, the stretching ratio of the thin product is 1.5 to 7 times, and the permanent deformation rate is at most 2%.
A propylene resin thin material for release paper base material.