JPH05117998A - Process release paper - Google Patents

Abstract

PURPOSE:To provide a process release paper excellent in adhesivity and surface smoothness, useful for e.g. producing synthetic leathers, consisting of a laminate made up of a substrate and a release layer which is made up of a PP interlayer and a surface layer consisting of a specific resin composition. CONSTITUTION:The objective process release paper consisting of a laminate made up of (A) a substrate 2 like kraft paper and (B) a release layer 3 made up of (1) an interlayer 4 and (2) a surface layer 5 (as shown in the figure). The interlayer 4 consists of a PP homopolymer resin with a melt flow rate(MFR) of 1-100g/10min, while the surface layer 5 consists of a resin composition comprising (a) 50-98wt.% of a PP 5-100g/10min in MFR and (b) 50-2wt.% of a long chain PE 0.1-40g/10min in MFR.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process release paper, and more particularly to a process release paper excellent in smoothness used for producing synthetic leather.

[0002]

2. Description of the Related Art Synthetic leather manufactured conventionally includes
Examples include polyurethane (PU) leather, semi-synthetic leather, and vinyl chloride (PVC) leather.

As a method for manufacturing PU leather, for example,
Process PU resin is applied on release paper and dried.
After solidifying, there is a method of laminating with a base cloth. In addition, as a method for producing semi-synthetic leather, paste P
There is a method in which a U resin is applied, dried and solidified, and then a PVC foam layer is formed and bonded to a base cloth.

Further, as a method for producing PVC leather, there is a method in which a PVC resin sol is applied onto step release paper, heated and gelled, and then a PVC foam layer is formed and laminated with a base cloth.

As a release paper used in the past, a single layer made of a polyolefin resin such as polypropylene (PP) was formed on a substrate to form a release layer.

[0006]

However, in the above-mentioned process release paper, the thickness unevenness of the polyolefin-based resin layer is apt to occur, and the smoothness of the polyolefin-based resin layer is low, so that the release layer exhibits uneven gloss. In particular, it does not have sufficient characteristics as a process release paper used for producing a flat synthetic leather product which requires a high degree of smoothness.

In order to improve the surface smoothness of the release paper, a resin composition layer of polypropylene and polyethylene is provided on the base material, and a layer made of homopolypropylene resin is provided on the resin composition layer. Attempts have been made to improve the adhesiveness between the base material and the release layer and the surface smoothness of the release layer as a mold layer, but a process release paper suitable for the production of synthetic leather that requires high smoothness is I couldn't get it.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a process release paper having a high degree of surface smoothness and having sufficient characteristics for the production of synthetic leather. ..

[0009]

In order to achieve such an object, the step release paper of the present invention comprises a base material and a release layer provided on the surface of the base material. Has a multilayer structure of an intermediate layer located on the side of the base material and a surface layer located on the opposite side of the base material with the intermediate layer interposed therebetween, and the intermediate layer is composed of a polypropylene homopolymer resin. The surface layer is composed of a resin composition in which 50 to 98% by weight is polypropylene and 50 to 2% by weight is long chain polyethylene.

[0010]

The release layer formed on the surface of the base material comprises an intermediate layer composed of polypropylene homopolymer resin,
-98% by weight is polypropylene and 50-2% by weight is long-chain polyethylene, and has a multilayer structure comprising a surface layer composed of a resin composition, and the intermediate layer has high adhesion between the base material and the release layer. And the surface smoothness of the release layer is greatly improved by the surface layer.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic sectional view showing an example of the process release paper of the present invention. In FIG. 1, the process release paper 1 is provided with a release layer 3 on one surface of a base material 2, the release layer 3 is an intermediate layer 4 in contact with the base material 2, and a surface layer formed on the intermediate layer 4. 5 and.

As the base material 2, kraft paper, high quality paper, imitation paper, art paper, coated paper and the like can be used.
The basis weight of the base material 2 is preferably about 80 to 200 g / m ² . The surface of the base material 2 on the side of the release layer 3 is the base material 2
In order to improve the adhesion between the release layer 3 and the release layer 3, heating or corona discharge treatment may be performed in advance.

The intermediate layer 4 constituting the release layer 3 is made of polypropylene homopolymer resin,
The thickness is preferably about 10 to 20 μm. The polypropylene homopolymer resin used for forming the intermediate layer 4 preferably has a melt flow rate (MFR) in the range of 1 to 100 g / 10 minutes. If the MFR is less than 1 g / 10 minutes, the spreadability will be insufficient, and if it exceeds 100 g / 10 minutes, neck-in will be severe during coextrusion described later, which is not preferable.

The surface layer 5 constituting the release layer 3 is composed of a resin composition in which 50 to 98% by weight is polypropylene and 50 to 2% by weight is long-chain polyethylene, and has a thickness of The thickness is preferably about 10 to 25 μm. Further, it is more preferable that 80 to 90% by weight of the resin composition is polypropylene and 10 to 20% by weight of long chain polyethylene. By setting the ratio of polypropylene and long-chain polyethylene in the surface layer 5 within the above range, the occurrence of uneven gloss in the surface layer 5 can be effectively prevented. Further, the MFR of polypropylene used for forming the surface layer 5 is preferably in the range of 5 to 100 g / 10 minutes, and the MFR of long-chain polyethylene is preferably in the range of 0.1 to 40 g / 10 minutes. If the MFRs of polypropylene and long-chain polyethylene are less than the above ranges, the malleability is insufficient, and if they exceed the above ranges, neck-in becomes severe during coextrusion described later, which is not preferable. Also, long-chain polyethylene has a density of 0.915 to 0.93.
It is preferably so-called high-pressure low-density polyethylene having a weight of 0 g / cm ³ . If polyethylene having a short-chain branch, so-called linear high-density polyethylene, or linear low-density polyethylene is used as the long-chain polyethylene, uneven thickness occurs during extrusion molding, which is not preferable.

As described above, the release layer 3 has a multilayer structure of the intermediate layer 4 and the surface layer 5, whereby the adhesiveness between the base material 2 and the release layer 3 is improved and the release layer 3 is smooth. Can be improved at the same time.

Such a release layer 3 has a two-layer structure composed of a layer made of polypropylene homopolymer resin and the above resin composition layer, which is melt-extruded and coated by a melt coextrusion machine. It is formed.

Next, the present invention will be described in more detail with reference to experimental examples. (Experimental example) Using 100 g / m ² of high-quality paper as a substrate,
The resin extruded from the first extruder (for forming the intermediate layer) of the melt coextruder and the resin extruded from the second extruder (for the surface layer formation) of the melt coextruder are shown in Table 1 below. A process release paper (Samples 1 to 4 and Comparative Samples 1 to 4) was prepared by using a combination of resins and adhering them at the joint between the extruder and the T-die to perform co-extrusion to form a release layer. .. The conditions for coextrusion were as follows.

(Coextrusion conditions) -Substrate speed: 100 m / min-First extruder Extruder: Diameter 90 mm, L / D = 29 T-die: 750 mm width, temperature = 310 ° C Extrusion amount: 50 kg / hr-No. 2 Extruder Extruder: Diameter 90 mm, L / D = 29 T die: 750 mm width, temperature = 300 ° C. Extrusion amount: 50 kg / hour-Intermediate layer thickness: 15 μm-Surface layer thickness: 15 μm

[0019]

[Table 1] Each process release paper created (Samples 1 to 4 and Comparative sample 1 to
Regarding 4), the suitability for laminating the base material and the release layer and the surface smoothness of the release layer were evaluated by visual judgment. The evaluation results are shown in Table 1.

As shown in Table 1, the process release papers of the present invention (Samples 1 and 2) have good laminating suitability and surface smoothness. In contrast, Comparative Samples 1 and 2 in which the intermediate layer was formed of a resin composition composed of polypropylene (resin B) and long-chain polyethylene (resin C) and the surface layer was formed of polypropylene homopolymer resin (resin A) The surface smoothness of the release layer was poor.

Comparative Samples 3 and 4, which also used long-chain polyethylene (resin C) for the intermediate layer, were inferior in both the laminating suitability of the base material and the release layer and the surface smoothness of the release layer. Further, the sample 5 in which the intermediate layer and the surface layer were formed of only the polypropylene homopolymer (resin A) had significantly poor laminating suitability.

Further, polypropylene (resin B) and long-chain polyethylene (resin C) of the resin composition constituting the surface layer
Samples 3 and 4 in which the ratio of C was changed within the range of the present invention were clearly superior to the above-mentioned Comparative Samples 1 to 5, but were smoother than the samples 1 and 2 in terms of surface smoothness of the release layer. A little inferior in terms of sex. Therefore, the ratio of polypropylene (resin B) and long-chain polyethylene (resin C) of the resin composition constituting the surface layer is 80 to 9 for polypropylene (resin B).
It has been found that 0% by weight and long-chain polyethylene (resin C) are preferably in the range of 10 to 20% by weight.

[0023]

As described in detail above, according to the present invention, the release layer formed on the surface of the substrate is composed of the intermediate layer composed of polypropylene homopolymer resin and 50 to 98% by weight of polypropylene. Since it has a multi-layer structure composed of a surface layer composed of a resin composition in which 50 to 2% by weight is long-chain polyethylene, the adhesiveness between the base material and the release layer is high, and the surface of the release layer is smooth. Enables process release paper with significantly improved properties.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an example of a step release paper of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Process release paper 2 ... Base material 3 ... Release layer 4 ... Intermediate layer 5 ... Surface layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location D21H 19/20

Claims (4)

[Claims] 1. A base material and a release layer provided on the surface of the base material, wherein the release layer is an intermediate layer positioned on the base material side, and the base material via the intermediate layer. Has a multilayer structure with a surface layer located on the opposite side to the intermediate layer, the intermediate layer is made of polypropylene homopolymer resin, and the surface layer has 50 to 98% by weight of polypropylene and 50 to 2
A process release paper comprising a resin composition whose weight% is long-chain polyethylene. 2. The melt flow rate (MFR) of the polypropylene is 5 to 100 g / 10 minutes, the MFR of the long-chain polyethylene is 0.1 to 40 g / 10 minutes, and the MFR of the polypropylene homopolymer resin is 1-100g /
The process release paper according to claim 1, which is 10 minutes. 3. The long-chain polyethylene has a density of 0.91.
The process release paper according to claim 1 or 2, which has a weight ratio of 5 to 0.930 g / cm ³ . 4. The release layer is formed by co-extruding the polypropylene homopolymer resin and the resin composition onto the surface of the base material. Process release paper described.