JP4118412B2 - Manufacturing method of injection molded body - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing an injection-molded body using a release film made of a polyolefin substrate on which a silicone resin layer is laminated.
[0002]
[Prior art]
The release film is used as a protective film for the adhesive layer in an adhesive film in which an adhesive layer is provided on a display medium such as a label, a seal, or a sticker.
[0003]
In the present specification, “adhesion” includes adhesion. Further, the expression “film” does not have a strict meaning with respect to thickness, but also includes a sheet.
[0004]
Such release films are roughly classified into those having paper as a base material and those having synthetic resin as a base material. For example, in the case of paper, polyethylene is laminated on the paper, and surface modification such as corona treatment is applied to the laminated surface as necessary, and a reactive silicone having releasability is applied and cured together with a crosslinking agent and a polymerization initiator. Is done. On the other hand, when a synthetic resin is used as a base material, a surface treatment for improving the adhesiveness with silicone as necessary on the sheet or film of the synthetic resin, for example, undercoat, corona discharge treatment, plasma discharge treatment, After the flame treatment, a mixture of methyl vinyl polysiloxane, methyl hydrogen polysiloxane and a polymerization catalyst containing a platinum group atom is applied to the surface of the synthetic resin and cured.
[0005]
The release film thus obtained functions as a protective film for the adhesive layer of the adhesive film. Then, the adhesive film is peeled off from the release film before use, and at this point, the release film becomes waste.
[0006]
In this way, the release film eventually becomes all waste. Generally, paper-based release paper is made by laminating polyolefin resin on paper, so if you want to recycle the waste release paper, you have to go through a lot of processes and time like milk cartons. However, it is extremely disadvantageous economically and must be disposed of by incineration.
[0007]
On the other hand, release films made of synthetic resin have not yet been widely used, and there are almost no reports on their reuse. In addition, regarding the reuse of the release film made of a synthetic resin, it is conceivable to re-pelletize. In this case, the presence of the silicone film layer causes the screw to slip during melt-kneading, and the waste release film becomes a screw. There is a concern that it is difficult to produce recycled pellets without getting into, and that the physical properties of the synthetic resin of the recycled pellets change significantly compared to the raw resin.
[0008]
The present inventors also tried to pelletize a release film having a vinyl chloride resin film as a base material, but confirmed that the above-mentioned problem exists.
[0009]
Therefore, the present situation is that such waste release film is usually discarded after being discarded.
[0010]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a practical and effective method for reusing the release film.
[0011]
[Means for solving problems]
As a result of intensive studies to achieve the above object, the present inventors have surprisingly found that the release film having a polyolefin base material made from a polyolefin resin is easily pelletized in a normal extruder. It can be found that when the amount of the silicone resin containing this is adjusted to a specific range and used as a raw material for an injection-molded article, an injection-molded article that can be sufficiently put into practical use is obtained, and the present invention. It came to complete.
[0012]
That is, the present invention, after use the release film obtained by forming a silicone resin layer on the polyolefin substrate surface as a protective film tacky adhesive film was recovered as waste release film made of polyolefin waste release film A method for use as a raw material for an injection-molded article, wherein the content of the silicone resin in the injection-molded article obtained by molding is adjusted to a range of 0.1 to 3% by weight. Is the method.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
In this invention, the polyolefin base material in a release film is comprised from well-known polyolefin resin, ie, polyethylene resin, polypropylene resin, etc. Examples of the polyethylene resin include high density polyethylene, low density polyethylene, and linear low density polyethylene. Examples of the polypropylene resin include a polypropylene resin homopolymer, a random copolymer of propylene and at least one other α-olefin, and a block copolymer. Examples of the α-olefin copolymerized with propylene include ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 3-methyl-1-butene, 4-methyl-1-pentene, and the like. Can be mentioned. Moreover, the mixture of these polyethylene resin and polypropylene resin may be sufficient. Among these, a resin having crystallinity is particularly preferable, and a polypropylene resin having a relatively high melting point is most preferable.
[0014]
General additives used for films and sheets can be added to the polyolefin resin. Specific additives include heat stabilizers, processing stabilizers, polymer crystal nucleating agents, chlorine scavengers, antiblocking agents and the like. These types and amounts are not limited as long as the effects of the present invention are not inhibited.
[0015]
The polyolefin substrate of the present invention may be a single layer or a multilayer formed of two or more types of layers. That is, a single-layer film obtained by molding a polyolefin resin alone, or a single film composed of two or more layers by multilayering two or more types of resins having different melting point and rigidity properties due to different resin monomer structures Methods are included. The polyolefin base material may be stretched or not. That is, even an unstretched film may be stretched uniaxially or more.
[0016]
Moreover, the silicone resin which comprises the silicone resin coating layer of the mold release film of this invention can be laminated | stacked on an olefin film, and the well-known silicone resin which has mold release property is used without a restriction | limiting in particular. For example, a polymer obtained by polymerizing and curing a mixture of a polymerization catalyst containing methyl vinyl polysiloxane, methyl hydrogen siloxane and a platinum group atom is generally used. Moreover, in the lamination | stacking of the said silicone resin, well-known processes, such as forming an anchor coat layer in the surface of a polyolefin base material, can be implemented without a restriction | limiting.
[0017]
Furthermore, these silicone resins are not limited as long as they are polymerized and cured using any method of heat, ultraviolet rays and electron beams as a polymerization form, as long as the effects of the present invention are not hindered.
[0018]
In the present invention, the amount of the silicone resin layer formed on a polyolefin substrate is preferably ^{0.03~3.5g / m 2, 0.05~3g / m} 2, in particular, 0.1 It is preferably ² g / m ² .
[0019]
That is, if the silicone resin coating layer formed on the polyolefin substrate is less than 0.03 g / m ^{2 with} respect to the polyolefin resin, the release property, which is the original purpose of the release film, varies and cannot be used practically. On the other hand, when the silicone resin layer formed on the polyolefin film exceeds 3.5 g / m ² with respect to the polyolefin resin, it is difficult to make a pellet by using a melt-kneading method to produce a regenerated pellet. Tend to. In addition, a release film having a silicone resin layer in an amount in the above range can be used as a waste release film as a raw material for an injection-molded product described later without adding a polyolefin for dilution separately. It can be used as it is, and is preferable.
[0020]
The waste release film of the present invention is a release film that remains after the release film obtained by the above method is used as a protective film for an adhesive film, and the adhesive film is peeled off from the release film. .
[0021]
The process of producing the waste release film will be described by taking a tack label as an example. Manufactures printing media (tack original) that is produced by laminating a release medium and a display medium with a pressure-sensitive adhesive layer, such as paper, polyethylene terephthalate, polyethylene, polystyrene, etc. Only the film part is punched out) to form a tack label, and the tack label is peeled off from the release film and attached to the adherend, thereby completing the role as the release film.
[0022]
In the present invention, the waste release film is collected and used as a raw material for an injection-molded body made of polyolefin.
[0023]
The collection may be transported directly from the place where the adherend is affixed to the place where it is used as a raw material for the polyolefin base material, or it may be regenerated, or it may be moved to the place where it was stamped and regenerated from there. There is also a case. In addition, the waste release film is generally collected in the form of a roll and collectively used for the regeneration process. Although it may collect | recover in the form of a roll, may collect | recover continuously and may collect | recover by a batch operation, this invention is not restrict | limited to these methods.
[0024]
In the present invention, the recovered waste release film can be melted by a known means and formed into an injection-molded product. In this case, a method of sequentially supplying the waste release film from the recovered roll to the extrusion machine sequentially, or after cutting the waste release film into a flare and adding heat to make flakes, extrusion molding Although the method etc. which are supplied to a machine are employ | adopted, unless the effect of this invention is inhibited, the method is not restrict | limited.
[0025]
In the present invention, when an injection molded article is molded using a waste release film, it is important to adjust the silicone resin content contained in the injection molded article to 0.1 to 3 wt%.
[0026]
That is, when the content of the silicone resin of the polyolefin base is less than 0.1 wt% with respect to the polyolefin resin, a polyolefin for dilution is required, which is not economical. On the other hand, when the polyolefin layer contains a silicone resin exceeding 3 wt%, the physical properties of the obtained injection molded article are deteriorated and the surface state is deteriorated, and it becomes difficult to obtain a practical injection molded article.
[0027]
The silicone resin content is more preferably 0.1 to 2.0 wt%, and most preferably 0.1 to 1.0 wt%.
[0028]
In addition, the polyolefin injection-molded article containing the silicone resin within the above range has almost no deterioration in physical properties as compared to the polyolefin injection-molded article not containing this, and the resulting injection-molded article has a tensile elongation at break. The effect that it is remarkably improved is exhibited.
[0029]
Moreover, when manufacturing an injection molded object, a color masterbatch can also be suitably added and colored for coloring as needed. Depending on the molding temperature and method, resin deterioration may be a concern due to thermal history, but in that case, a master batch of a heat stabilizer or a processing stabilizer can be added as appropriate.
[0030]
As a method of adjusting the content of the silicone resin within these ranges, a method of adjusting the amount of the silicone resin layer to be applied and cured on the polyolefin substrate, a polyolefin resin is used together with a waste release film, and diluted with the polyolefin resin. The method of doing is mentioned.
[0031]
【The invention's effect】
According to the method of the present invention, after using a release film formed by forming a silicone resin layer on at least one surface of a polyolefin substrate surface, the amount of the silicone resin can be adjusted when reused as a raw material for injection molded products. The obtained injection-molded product has a significantly improved breaking elongation strength without a significant decrease in general physical properties such as bending elastic modulus, and its practical value is extremely high.
[0032]
【Example】
Hereinafter, although an example explains using the present invention, the present invention is not limited to these.
[0033]
(Evaluation measurement method)
[Quantification of silicone resin]
The amount of silicon was quantified using a calibration curve prepared in advance by quantifying the amount of silicon using a fluorescent X-ray measuring apparatus (Lab-X3000) manufactured by Oxford.
[0034]
Example 1
(Adjustment of raw resin)
Melt flow rate 7.0 g / 10 min. 100 parts by weight of crystalline homopolypropylene, 0.1 part by weight of 2,6-di-t-butylhydroxytoluene as an antioxidant, 0.1 part by weight of calcium stearate as a chlorine scavenger, and 10 wtppm of polycyclopentene using a Henschel mixer And mixed for 5 minutes. Thereafter, the composition was pelletized at 230 ° C. using an extrusion granulator having a diameter of 60 mm. Hereinafter referred to as raw material pellet A.
[0035]
(Cast film creation)
A cast film was prepared using the raw material pellet A by the following method.
[0036]
Pellets A were supplied to an extruder having a screw diameter of 75 mm, extruded from a T die at a resin temperature of 230 ° C., and a single layer film having a thickness of 60 μm was obtained through a 30 ° C. cooling roll. Subsequently, corona discharge treatment was performed so that the wettability index of one surface was 40 mN / m, and then aging was performed at 40 ° C. for 24 hours.
[0037]
(Release processing)
A mold release silicone (LTC760A manufactured by Toray Dow Corning Silicone Co., Ltd .; a solution in which 100 parts and SRX-212cat .; 1 part are mixed) is applied to the corona discharge treated surface of the cast film using a gravure coater. Coating is performed so that the solid content concentration of the conductive silicone is 0.1 g / m ^2, and then the solvent is removed and the silicone resin is cured through a drying oven at 120 ° C., and the silicone resin is laminated on the cast film. did. This is hereinafter referred to as a separator.
[0038]
(Adhesion processing and bonding of display media)
An adhesive (manufactured by Nippon Synthetic Chemical Co., Ltd .: Coponil 8711; solution obtained by mixing 100 parts and Coronate L55E; 1.75 parts) was applied to the separator's silicone coating surface using a gravure coater to give a solid content concentration of 20 g / m ^2. Then, the solvent was removed continuously through a drying oven at 100 ° C. Subsequently, a polyester film (Toyobo PET: E5100) serving as a display medium was laminated on the adhesive side. Then, it aged at 40 degreeC for 50 hours. Hereinafter, it is referred to as an adhesive raw material.
[0039]
(Recycled pelletization)
The PET film which becomes the display medium of the adhesive original fabric was peeled off, and only the separator was wound on a roll. The used separator wound around the roll was melted, formed into a sheet, and cut into a regenerated pellet using a regenerating granulator (manufactured by Hitachi Zosen; High Luder).
[0040]
(Creation of injection molded body)
An injection-molded body was prepared using the Nikko 150T injection molding machine using the obtained recycled pellets.
[0041]
Moreover, the physical properties of these molded products were performed in accordance with ASTM.
[0042]
The obtained silicone resin contained in the molded body was 0.17 wt%.
[0043]
The physical properties of the injection molded product are summarized in Table-1.
[0044]
Example 2
The same procedure as in Example 1 was conducted except that the solid content concentration of the releasable silicone was adjusted to 0.3 g / m ² when performing the release treatment of Example 1. The results are summarized in Table 1.
[0045]
Example 3
The same procedure as in Example 1 was performed except that the solid content concentration of the releasable silicone was adjusted to 0.6 g / m ² when the mold release treatment of Example 1 was performed. The results are summarized in Table 1.
[0046]
Example 4
It carried out similarly to Example 1 except having prepared the raw material resin hung up below and producing 2 types and 3 layer cast films.
[0047]
(Adjustment of raw resin)
Melt flow rate containing 0.2 mol% of ethylene 7.0 g / 10 min. 100 parts by weight of crystalline random polypropylene, 0.1 part by weight of 2,6-di-t-butylhydroxytoluene as an antioxidant, and 0.1 part by weight of calcium stearate as a chlorine scavenger for 5 minutes using a Henschel mixer Mixed. Thereafter, the composition was pelletized at 230 ° C. using an extrusion granulator having a diameter of 60 mm. Hereinafter referred to as raw material pellet B.
[0048]
(Creation of 2 types, 3 layers cast film)
Resin Pellet A from the center layer using a three-layer three-layer co-extrusion machine consisting of two extruders for the center layer with a screw diameter of 75 mm and two sub-extruders for the surface layer with a screw diameter of 50 mm. Extrusion was performed at a temperature of 230 ° C., and pellets B were extruded at 230 ° C. from two sub-extruders. Subsequently, corona discharge treatment was performed so that the wettability index of one surface was 40 mN / m, and then aging was performed at 40 ° C. for 24 hours.
[0049]
The results are summarized in Table 1.
[0050]
Example 5
Similar to Example 1 except that the solid content concentration of the releasable silicone was adjusted to 0.3 g / m ² during the mold release treatment of Example 1 using the two-type three-layer cast film prepared in Example 4. Went to. The results are summarized in Table 1.
[0051]
Example 6
Similar to Example 1 except that the solid content concentration of the releasable silicone was adjusted to 0.6 g / m ² during the release treatment of Example 1 using the two-type three-layer cast film prepared in Example 4. Went to. The results are summarized in Table 1.
[0052]
Comparative Example 1
The same procedure as in Example 1 was performed except that the mold release treatment performed in Example 1 was not performed.
[0053]
As a result, it was not possible to peel off the PET film serving as the adhesive medium display medium and wind only the separator around the roll, so that only the so-called cast film was regenerated and pelletized, and the physical properties of the injection-molded article were evaluated. The results are summarized in Table 1.
[0054]
Comparative Example 2
Melt flow rate 7.0 g / 10 min. 100 parts by weight of crystalline homopolypropylene, 0.5 parts by weight of silicone resin particles (particle size 2 μm), 0.1 parts by weight of 2,6-di-t-butylhydroxytoluene as an antioxidant, calcium stearate as a chlorine supplement 0.1 part by weight and 10 wtppm of polycyclopentene were mixed for 5 minutes using a Henschel mixer. Thereafter, the composition was pelletized at 230 ° C. using an extrusion granulator having a diameter of 60 mm. Hereinafter referred to as raw material pellet C.
[0055]
It carried out like Example 1 except having used pellet C instead of the pellet A used in Example 1, and not having performed mold release processing.
[0056]
As a result, it was not possible to peel off the PET film serving as the adhesive medium display medium and wind only the separator around the roll, so that only the so-called cast film was regenerated and pelletized, and the physical properties of the injection-molded article were evaluated. The results are summarized in Table 1.
[0057]
[Table 1]

Claims (2)

After use the release film obtained by forming a silicone resin layer on the polyolefin substrate surface as a protective film tacky adhesive film, recovered as waste release film, the waste release film as a raw material for injection molded article made from the polyolefin A method for producing an injection-molded article, characterized in that the content of the silicone resin in the injection-molded article obtained by molding is adjusted to a range of 0.1 to 3% by weight. The method for producing an injection-molded article according to claim 1, wherein crystalline polypropylene is used as the polyolefin substrate.