JP6434282B2 - Method for producing surface protective film - Google Patents

Description

  The present invention relates to a method for producing a surface protective film.

  Surface protection films are widely used to prevent scratches and dirt during processing and transportation of surfaces such as synthetic resin plates, decorative plywood, and metal plates.

  The surface protective film generally has a structure in which an adhesive layer is provided on one side of a base material layer made of a polyolefin-based thermoplastic resin such as polyethylene and polypropylene, and has good adhesiveness (temporary adhesion). In addition, it must be possible to peel off various surfaces without being contaminated with adhesives after use. The reason why polyolefin-based thermoplastic resin is used for the base material layer is not only excellent in moisture resistance, chemical resistance, electrical insulation, etc., but also generates no toxic gas even if incinerated after use. This is because there are few problems in terms of processing.

  On the other hand, for the adhesive layer, for example, a thermoplastic elastomer such as styrene-butadiene-styrene block copolymer (SBS) or styrene-ethylene / butylene-styrene block copolymer (SEBS) is used, and a tackifying resin is used. It is formed using a mixed adhesive composition. The reason is that when an adhesive film is formed by using a coextrusion molding method with a base layer and an adhesive layer, the adhesive composition can be applied to a polyolefin resin substrate. This is because the force is improved and the contamination (adhesive residue) due to the adhesive layer on the adherend after peeling is small.

  On the other hand, after dry blending the thermoplastic elastomer and the tackifying resin, when the melt-extrusion is carried out by supplying to the extruder, the tackifying resin is scattered or the supply port wall surface Adhesive constituent materials are not supplied to the extruder, and an adhesive layer having a predetermined blending ratio is not formed accurately. Can't get. Even if the tackifying resin is in the form of pellets, the same problem occurs because it is pulverized by the screw in the vicinity of the supply port of the extruder and becomes powdery.

  Therefore, it has been studied to use a master batch in which a predetermined amount of tackifying resin is melt-mixed in advance with a thermoplastic elastomer. Patent Document 1 discloses a method for producing a surface protective film by co-extrusion of a base material layer made of a thermoplastic resin and a pressure-sensitive adhesive layer containing a block copolymer and a tackifying resin. Pellets produced by melt blending the total amount and at least a part of the block copolymer at a blending ratio of 200 to 500 parts by weight of the tackifying resin with respect to 100 parts by weight of the block copolymer, together with the remaining adhesive material A method for producing a surface protective film is described in which the pressure-sensitive adhesive layer is formed by feeding to an extruder.

JP-A-11-323295

  However, as described in Patent Document 1, when 200 to 500 parts by weight of the tackifier resin is blended with 100 parts by weight of the thermoplastic elastomer, there is a problem that the obtained master batch pellet is brittle. If the master batch pellet is brittle, the pellet may be pulverized by a screw near the supply port of the extruder into a powder, and the powder may adhere to the screw and cannot be supplied. If less than 200 parts by weight of a tackifier resin is blended with 100 parts by weight of the thermoplastic elastomer, there is no problem that the resulting master batch pellets are brittle, but there is a new problem that the pellets become sticky and block.

  Then, an object of this invention is to provide the manufacturing method of the surface protection film which can prevent blocking of the pellets at the time of manufacture.

The present invention is a method for producing a surface protective film having a base material layer made of a thermoplastic resin and an adhesive layer formed on the base material layer,
Styrenic block copolymer as a thermoplastic elastomer having a glass transition temperature measured by DSC method of −40 ° C. or higher, or a copolymer obtained by hydrogenation thereof, and 100 parts by weight of the thermoplastic elastomer Producing a masterbatch mixed with 50 to 190 parts by weight of a tackifying resin;
It is a manufacturing method of the surface protection film which has the process of supplying the said masterbatch and the component which forms the remaining adhesive layer to an extruder, and coextruding with the said thermoplastic resin.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the surface protection film which can prevent blocking of the pellets at the time of manufacture can be provided.

It is sectional drawing which shows the structural example of the surface protection film which concerns on this invention.

  The surface protective film according to the present invention includes, for example, a base material layer 1 made of a thermoplastic resin and an adhesive layer 2 formed on the base material layer 1 as shown in FIG. The pressure-sensitive adhesive layer 2 contains a thermoplastic elastomer and a tackifying resin because there is little anchoring force and adhesive residue with the base material layer 1.

  The thermoplastic resin for forming the base material layer 1 is preferably a polyolefin-based resin because no toxic gas is generated even when incinerated after use, and there are few problems in the post-treatment. Examples of polyolefin resins include polyethylene, ethylene-α olefin copolymer, propylene-α olefin copolymer, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, ethylene-nbutyl acrylate copolymer, polypropylene. Etc. The thermoplastic resin for forming the base material layer 1 may be used individually by 1 type, and may be used in combination of 2 or more type. In addition, a light stabilizer, an ultraviolet absorber, an antioxidant, a filler, a lubricant, and the like can be added to the thermoplastic resin as necessary.

  As the thermoplastic elastomer for forming the pressure-sensitive adhesive layer 2, a styrene block copolymer or a copolymer obtained by hydrogenating it can be used. The styrenic block copolymer is generally a block copolymer represented by A-B-A, or a block copolymer represented by A-B-A and a block copolymer represented by A-B. Wherein A is a styrene polymer block and B is another polymer block. Other polymer blocks include: olefin polymer blocks such as ethylene polymer blocks, propylene polymer blocks, butylene polymer blocks; diene polymer blocks such as butadiene polymer blocks and isoprene polymer blocks; Examples thereof include a hydrogenation block obtained by hydrogenating at least a part of the combined block. The weight ratio of A and B is A / B = 5/95 to 50/55.

  In particular, as the styrene block copolymer, styrene-ethylene / butylene-styrene block copolymer (SEBS), styrene-ethylene / propylene-styrene block copolymer (SEPS), styrene-butadiene-styrene block copolymer. It is preferable to use a polymer (SBS), a styrene-isoprene-styrene type block copolymer (SIS), or a styrene-isobutylene-styrene type block copolymer (SIBS).

  In the present invention, it is important that the glass transition temperature (hereinafter referred to as “Tg (DSC)”) of the thermoplastic elastomer measured by the DSC method is −40 ° C. or higher. When Tg (DSC) is less than −40 ° C., a master batch pellet described later becomes sticky and blocks. Tg (DSC) is preferably −35 ° C. or higher, more preferably −30 ° C. or higher, particularly preferably −25 ° C. or higher, and can also be −20 ° C. or higher. Further, Tg (DSC) is preferably 30 ° C. or less, more preferably 25 ° C. or less, and particularly preferably 20 ° C. or less, from the viewpoint of not impairing the tackiness of the adhesive. Preferably, it can also be 15 degrees C or less. In addition, Tg (DSC) shall be measured by the method of JISK7121 using Shimadzu differential scanning calorimeter DSC-60 (brand name) by Shimadzu Corporation.

  The tackifying resin for forming the pressure-sensitive adhesive layer 2 may be any resin capable of imparting tackiness to the pressure-sensitive adhesive layer 2, and is a rosin resin, terpene resin, aliphatic petroleum resin, alicyclic petroleum. Resin, aromatic resin and the like. The tackifying resin is preferably in the form of powder or pellets at room temperature (25 ° C.).

  The amount of the tackifying resin may be appropriately set in consideration of the adhesive performance of the surface protective film, but the amount of the tackifying resin is 1 to 50 with respect to 100 parts by weight of the thermoplastic elastomer contained in the entire pressure-sensitive adhesive layer 2. The amount is preferably 1 part by weight, more preferably 1 to 30 parts by weight, and still more preferably 1 to 20 parts by weight.

  The material forming the pressure-sensitive adhesive layer 2 includes a thermoplastic elastomer and a tackifier resin as described above, but may also include additives such as an ultraviolet ray inhibitor, an antioxidant, a filler, and a lubricant as necessary. it can.

  In the present invention, a master batch in which a thermoplastic elastomer and a tackifying resin are mixed in advance is manufactured in manufacturing the surface protective film as described above. The compounding ratio of the thermoplastic elastomer and the tackifier resin in the master batch is less than 200 parts by weight of the tackifier resin with respect to 100 parts by weight of the thermoplastic elastomer so that the resulting master batch pellets are not brittle. The blending amount of the tackifier resin with respect to 100 parts by weight of the thermoplastic elastomer is preferably 190 parts by weight or less, more preferably 160 parts by weight or less, and still more preferably 120 parts by weight or less. Further, from the viewpoint of effectively exhibiting the function as a master batch, the compounding amount of the tackifier resin is preferably 50 parts by weight or more, and 70 parts by weight or more with respect to 100 parts by weight of the thermoplastic elastomer. More preferably, it is more preferably 80 parts by weight or more.

  Subsequently, the masterbatch and the component which forms the remaining adhesive layer are supplied to the adhesive layer extruder. Usually, a necessary amount of tackifying resin is supplied by a master batch, and a shortage of thermoplastic elastomer is added, but a part of the tackifying resin may be added separately. Additives to be added as necessary may be added to the master batch or may be added at this stage.

  And it coextrudes with the thermoplastic resin for forming the base material layer 1. More specifically, by a two-layer coextrusion method in which the thermoplastic resin for forming the base layer 1 is supplied to the base layer extruder, and each material is co-extruded from one die from two extruders. Molded in one piece. By carrying out like this, the surface protection film in which the adhesive layer 2 was formed on the base material layer 1 is obtained.

  The thickness of the base material layer 1 in the obtained surface protective film can be 20-100 micrometers, for example. The thickness of the pressure-sensitive adhesive layer 2 in the obtained surface protective film can be set to 2 to 50 μm, for example. Moreover, other layers, such as a mold release layer for making it easy to expand | deploy the surface protection film wound by roll shape, may be formed in the surface protection film as needed.

<Example 1>
Low-density polyethylene (manufactured by Nippon Polyethylene, trade name: Novatec LC522) as a thermoplastic resin is used for the base material layer, and styrene-ethylene / propylene-styrene type block copolymer as a thermoplastic elastomer is used for the adhesive layer. Using coalescence (SEPS, manufactured by Kuraray, trade name: Hiblar 7311, Tg (DSC): −31 ° C.) and an alicyclic petroleum-based resin (trade name: Alcon P140, manufactured by Arakawa Chemical Industries) as a tackifier resin. A surface protective film having the structure shown in FIG. 1 was produced.
Specifically, first, 100 parts by weight of a pellet-shaped thermoplastic elastomer and 100 parts by weight of a tackifying resin were melt-mixed to produce a master batch pellet. Next, the master batch pellets and the thermoplastic elastomer pellets were put into an adhesive layer extruder so that the compounding amount of the tackifier resin with respect to 100 parts by weight of the thermoplastic elastomer was 10 parts by weight. And the surface protection film with a base material layer thickness of 50 micrometers and an adhesive layer thickness of 10 micrometers was obtained by coextruding with the thermoplastic resin separately supplied to the extruder for base material layers.

<Example 2>
Example 1 except that styrene-ethylene / butylene-styrene type block copolymer (SEBS, manufactured by JSR, trade name: Dynalon 8903P, Tg (DSC): −32 ° C.) was used as the thermoplastic elastomer. Thus, a surface protective film was obtained.

<Example 3>
Except for using a styrene-ethylene / butylene-styrene type block copolymer (SEBS, manufactured by Asahi Kasei Chemicals, trade name: SOESE1605, Tg (DSC): 9 ° C.) as the thermoplastic elastomer, In the same manner as in Example 1, a surface protective film was obtained.

<Example 4>
As a thermoplastic elastomer, a styrene-ethylene / butylene-styrene type block copolymer (SEBS, manufactured by Asahi Kasei Chemicals, trade name: SOESE1605, Tg (DSC): 9 ° C.) is used as a tackifier resin. A surface protective film was obtained in the same manner as in Example 1 except that a terpene resin (trade name: YS Resin PX1150N, manufactured by Yasuhara Chemical Co., Ltd.) was used.

<Comparative Example 1>
Example 1 except that a styrene-ethylene / propylene-styrene type block copolymer (SEPS, manufactured by Kuraray, trade name: Septon 2063, Tg (DSC): -56 ° C.) was used as the thermoplastic elastomer. Thus, a surface protective film was obtained.

<Comparative Example 2>
A styrene-ethylene / butylene-styrene type block copolymer (SEBS, manufactured by Kraton Polymer, trade name: Kraton G1657, Tg (DSC): −52 ° C.) is used as the thermoplastic elastomer, and a terpene resin as a tackifier resin. A surface protective film was obtained in the same manner as in Example 1 except that Yashara Chemicals (trade name: YS Resin PX1150N) was used.

<Evaluation: Blocking>
“○” indicates that the master batch pellets stored in the bag did not adhere to each other, and those that could be easily crushed even if they were attached, and those that were attached and could not be easily crushed It was set as “x”.

<Evaluation: Extrusion stability>
When the material that forms the adhesive (master batch pellets and thermoplastic elastomer pellets) is supplied from the hopper of the extruder, the material that has been able to stably extrude the material that forms the adhesive is “○”. The remaining pellets that were worn were designated as “x”.

  From the above results, it can be seen that according to the present invention, blocking of pellets during production can be prevented even when the blending amount of the tackifying resin is small. That is, the supply of the material forming the pressure-sensitive adhesive is stabilized and the molding workability is improved. Moreover, since the blending ratio of the thermoplastic elastomer and the tackifying resin is also stabilized, the quality of the surface protective film is stabilized.

1 Base material layer 2 Adhesive layer

Claims (5)

A method for producing a surface protective film having a base material layer made of a thermoplastic resin and an adhesive layer formed on the base material layer,
Styrenic block copolymer as a thermoplastic elastomer having a glass transition temperature measured by DSC method of −40 ° C. or higher, or a copolymer obtained by hydrogenation thereof, and 100 parts by weight of the thermoplastic elastomer Producing a masterbatch mixed with 50 to 190 parts by weight of a tackifying resin;
The manufacturing method of the surface protection film which has the process of supplying the said masterbatch and the component which forms the remaining adhesive layer to an extruder, and coextruding with the said thermoplastic resin.   The method for producing a surface protective film according to claim 1, wherein the thermoplastic elastomer has a glass transition temperature measured by a DSC method of −32 to 9 ° C. 3. The styrene block copolymer is a styrene-ethylene / butylene-styrene block copolymer (SEBS), a styrene-ethylene / propylene-styrene block copolymer (SEPS), or a styrene-butadiene-styrene block copolymer. coalescence (SBS), styrene - isoprene - styrene type block copolymer (SIS), or styrene - isobutylene - method for producing a surface-protective film according to claim 1 or 2 is a styrene block copolymer (SIBS). The method for producing a surface protective film according to any one of claims 1 to 3 , wherein the tackifying resin is an alicyclic petroleum resin or a terpene resin. The surface according to any one of claims 1 to 4, wherein the pressure-sensitive adhesive layer contains the thermoplastic elastomer and 1 to 50 parts by weight of the tackifying resin with respect to 100 parts by weight of the thermoplastic elastomer. A method for producing a protective film.

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