JP2007245442A - Laminate and sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the weatherable deterioration of a laminate itself in the laminate composed of at least two layers, that is, a polyolefin resin layer and a hard coat layer. <P>SOLUTION: This laminate is constituted by laminating at least the transparent polyolefin resin layer containing an ultraviolet absorber and the hard coat layer based on an isocyanate curable resin, and 1-20 wt.% of a light stabilizer containing a hydroxy group in its chemical structure and 1-10 wt.% of a benzotriazole or hydroxyphenyltriazine type ultraviolet absorber are contained in the hard coat layer. Further, the hard coat layer together contains a light stabilizer containing a hydroxy group in its structural formula and a light stabilizer containing no hydroxy group and the present ratio of the former and the latter is within a range of 20/80-80/20. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laminate and a sheet comprising a polyolefin resin layer and a hard coat layer, for example, a decorative pattern, a poster, a barcode, a sign, etc. The present invention relates to a laminate and a sheet suitable for a weather-resistant protective film for protecting from the influence of wind and rain, temperature, and the like.

  Conventionally, general printed materials are not highly resistant to ultraviolet rays, water, etc., so the surface layer is used in applications that require high resistance to them, such as decorative sheets for outdoor applications and posters for outdoor postings. In addition, by sticking a transparent film using an acrylic or fluorine-based material to the surface layer of the printed material, deterioration with time of the printed material is suppressed.

  As the material for this transparent film, polyethylene terephthalate and polyolefin-based materials are also preferably used because of their low cost, but in general, compared to the acrylic and fluorine-based materials described above, they are resistant to ultraviolet rays. Inferior in terms of

Therefore, in order to compensate for such drawbacks, a hard coat layer in which an ultraviolet absorber or a light stabilizer is appropriately added to polyethylene terephthalate or polyolefin resin, or a high concentration of an ultraviolet absorber or a light stabilizer is added. Is used (for example, see Patent Documents 1 to 3 as an example of a decorative sheet).
JP 2001-040113 A JP 2001-181420 A JP 2001-315270 A

  However, depending on the type and addition amount of the above-described method, the hard coat layer itself is deteriorated at an early stage due to the influence of ultraviolet rays, etc. In some cases, it is impossible to suppress deterioration of the resin for a long period of time.

  Therefore, the present invention provides a laminate and sheet capable of improving the weather resistance of a printed matter, for example, by suppressing the weather resistance deterioration of the laminate itself in a laminate of two or more layers of a polyolefin resin layer and a hard coat layer. The purpose is to provide.

In order to achieve the above object, the laminate of the present invention comprises a transparent polyolefin resin layer containing at least an ultraviolet absorber and a hard coat layer mainly composed of an isocyanate curable resin, and has a hydroxyl group in the chemical structure. And a hard-coat layer containing a benzotriazole or hydroxyphenyltriazine-based ultraviolet absorber.
The sheet of the present invention is a sheet in which a laminate and a substrate are joined, and the laminate comprises a transparent polyolefin resin layer containing at least an ultraviolet absorber and a hard coat layer mainly composed of an isocyanate curable resin. And a light stabilizer containing a hydroxyl group in the chemical structure, and a benzotriazole or hydroxyphenyltriazine-based ultraviolet absorber in the hard coat layer.
Further, the composition is characterized by containing 1 to 20 percent by weight of the light stabilizer and further containing 1 to 10 percent by weight of the ultraviolet absorber.
The hard coat layer includes both a light stabilizer containing a hydroxyl group and a light stabilizer not containing a hydroxyl group in the structural formula, and the abundance ratio of the light stabilizer to the light stabilizer is 20/80 to 80 / It is characterized by being in the range of 20.

According to the laminate and sheet of the present invention, the hydroxyl group of the light stabilizer containing a hydroxyl group in the chemical structure and the isocyanate cause a urethane bond, so that the light stabilizer exists in a more stable state in the hard coat layer. Can continue. Thereby, the weather resistance deterioration of the hard coat layer due to the bleed of the light stabilizer is suppressed, and the benzotriazole or hydroxyphenyltriazine-based UV absorber in the hard coat layer can continue to exhibit the UV absorbing effect in the layer. As a result, it is possible to protect the printed material for a long period of time by continuously blocking the entry of ultraviolet rays into the printed material for a long time.
In addition, by blending with a light stabilizer that does not contain a hydroxyl group, an appropriate transition of the light stabilizer from the hard coat layer to the transparent polypropylene resin layer is performed, and on the laminated surface of the hard coat layer and the transparent polypropylene resin layer, Resistance to adhesion ultraviolet rays is continuously maintained.
As a result, for example, if the laminate of the present invention is used for the surface protective layer of a printed material having a woodgrain printed pattern, a decorative sheet that suppresses the deterioration with time of the weather resistance of the printed pattern layer can be obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a side sectional view for explaining an example of a laminate according to an embodiment of the present invention, in which a hard coat layer 1 and a transparent polyolefin resin layer 2 are laminated in order from the surface side. Note that the hard coat layer and the transparent polyolefin resin layer may be multilayered as necessary.

First, the hard coat layer 1 has a role of protecting the printed matter and the transparent polyolefin resin layer from various disturbances, and is required to have scratch resistance, stain resistance, ultraviolet resistance, and the like. The effect of adjusting the properties and surface gloss is also required.
As the transparent (or translucent) material used, polyurethane, acrylic, acrylic silicon, fluorine, epoxy, vinyl, polyester, melamine, and the like are preferably used. In this case, it is desirable to use a prepolymer having a hydroxyl group in a part of the above material system and a urethane reaction by an isocyanate prepolymer.

  Further, since the hard coat layer 1 is present on the outermost surface, it is directly affected by heat and rain as well as ultraviolet rays from sunlight. Therefore, the hard coat layer 1 must fully consider the influence of weather resistance, and it is essential to add a light stabilizer or an ultraviolet absorber. However, due to heat, light, rain, etc., light stabilizers and UV absorbers may be bleed or washed away over time, causing resin deterioration. This accelerates the release of agents and light stabilizers out of the hard coat layer.

Therefore, in the laminated body of this example, by using a light stabilizer that contains a hydroxyl group in its chemical structure, the hydroxyl group of the weathering agent and the hard coat layer are cured in the course of curing by the urethane reaction of the hard coat layer. A cross-linked structure is obtained by reaction with an isocyanate group in the agent, and problems such as bleeding or washing away with time can be almost eliminated.
As a result, since the hard coat layer continues to exist for a long period of time, the release of the UV absorber contained in the hard coat layer is also suppressed, and the UV resistance of the hard coat layer is suppressed. And other weather resistance performance will last for a long time.

The UV absorber added to the hard coat layer is preferably a benzotriazole or hydroxyphenyl triazine type, and the benzophenone UV absorber has a quick decline in function compared to the above two types. Not suitable.
Benzotriazole-based UV absorbers have sufficient UV-absorbing ability even in a small amount in the initial stage, but the absorption efficiency tends to decrease due to sublimation over time.

On the other hand, hydroxyphenyltriazine-based ultraviolet absorbers have little change in the ultraviolet absorption function between the initial and lapse of time, have high holding power, and are excellent in stability. Even when using the same amount, the price of the final product tends to be high, and it is difficult to add much.
As described above, since the benzotriazole-based UV absorber and the hydroxyphenyltriazine-based UV absorber have their respective characteristics, it is possible to use a technique that takes advantage of each advantage by using them together. .

  The content of the light stabilizer and the ultraviolet absorber in the hard coat layer is not particularly specified, and generally, the larger the amount added, the stronger the effect and the longer it lasts. The agent is preferably contained in an amount of 1 to 20 percent by weight, more preferably about 2 to 10 percent, and the ultraviolet absorber is preferably contained in an amount of 1 to 10 percent, more preferably about 2 to 8% by weight. When the weight ratio is lower than this range, sufficient weather resistance performance cannot be exhibited. Conversely, when the weight ratio is high, color change and physical property change of the hard coat layer are likely to occur.

  As for the thickness of the hard coat layer, about 1 to 40 μm is appropriate, but it varies depending on its use, required quality level, resin used, etc. May be determined as appropriate. As an example, in applications that require high scratch resistance and weather resistance, about 20 to 40 μm is desirable, and in applications that require lapping suitability and the like, it is desirably within the range of 1 to 10 μm.

  Also, the laminating method of the hard coat layer may be selected according to the properties, viscosity, and coating amount of the coating liquid. It may be selected from general coating methods such as gravure coating, micro gravure coating, comma coating, knife coating, and die coating. Alternatively, a method may be used in which a coating is applied in advance on a separately prepared carrier sheet and then laminated on the transparent polyolefin resin layer using a transfer method.

  Hard coat coating solutions are solvent-based, solvent-free, water-based, emulsion-based, hot-melt-based, etc., taking into account drying properties, heat resistance of the sheet, blocking property after drying, adhesion to the sheet, etc. It is good to select suitably.

  With respect to the light stabilizer in the hard coat layer, it is possible to further improve the weather resistance stability of the laminate of the present invention by using a mixture of a light stabilizer having a hydroxyl group and a light stabilizer having no hydroxyl group. Become. Compared with a light stabilizer having a hydroxyl group, a light stabilizer that does not have a hydroxyl group is likely to shift to a transparent polyolefin resin layer over time. produce.

  Generally, polyolefin resin is non-polar and has poor adhesion to dissimilar materials. To compensate for this, various oxidation treatments such as corona treatment, ozone treatment, and plasma treatment are performed. It causes deterioration of the resin outermost layer. If the light stabilizer not having a hydroxyl group is contained in the hard coat layer, the light stabilizer is transferred to the oxidation treatment portion of the outermost layer in the process of transferring the light stabilizer to the transparent polyolefin resin layer. The effect of suppressing deterioration due to light in this portion can be obtained.

  The mixing ratio of the light stabilizer having a hydroxyl group and the light stabilizer not having a hydroxyl group needs to be in the range of 20/80 to 80/20 in order to sufficiently bring out both effects. In the case of a blending ratio outside this range, it becomes difficult to exhibit both effects.

  In order to obtain almost the same effect as protection near the lamination interface by migration of the light stabilizer, it is also possible to add a light stabilizer to the transparent polyolefin resin in advance. It is not economical because it is added not only to the vicinity of the required lamination interface but also to the entire polyolefin resin layer, and in the method of adding a light stabilizer to the transparent polyolefin resin in advance, the mechanical properties of the resin layer Considering the transparency and the like, the light stabilizer cannot be added to the hard coat layer at a very high concentration, so the effect is limited.

Next, the transparent polyolefin resin layer 2 will be described.
The transparent polyolefin resin layer 2 may be a homopolymer, that is, a homopolymer, a random polymer copolymer or a block polymer copolymer copolymerized with ethylene, butene, or the like, or two or more types of resin components generated by polymer alloy The mixture which consists of may be sufficient.

For example, in order to provide scratch resistance, it is preferable to use highly crystalline homopolypropylene as the transparent polyolefin resin layer 2, and to increase the reproducibility of printed matter, if random polypropylene containing ethylene is used, It is good for improving the transparency of the resin. In addition, when the shape of the printed material is not flat and has a complicated shape, or when wrapping a complicated shape, random polypropylene that is softened by increasing the amount of ethylene content, Examples thereof include a method of using a material obtained by adding an elastomer component to an arbitrary polypropylene such as homopolypropylene having a low crystallinity or a polymer alloy.
The transparent polyolefin resin 2 used here includes a heat stabilizer, a flame retardant, an ultraviolet absorber, a light stabilizer, an anti-blocking agent, a catalyst scavenger, a colorant within a range that maintains transparency, if necessary, A light scattering agent, a gloss adjusting agent, etc. for making translucent can be added.

  In addition, a filler component can be added to the transparent polyolefin resin layer 2 in addition to the resin and additives in consideration of improvement in machinability and other physical properties. As filler components, there are urethane crosslinked particles, acrylic crosslinked particles, melamine resin, natural collagen, etc. as organic component fillers, and as inorganic fillers, alumina, silica, silicon nitride, silicon carbide, glass beads, aluminum hydroxide , Calcium carbonate, and the like.

Further, in order to provide adhesion between a protected surface such as a printed matter and the laminate, (a) an adhesive material is laminated on the outermost layer on the printed matter side of the transparent polypropylene resin layer, and (b) an adhesive layer is made of transparent polypropylene. The method of providing in the middle of a resin layer and a printed matter layer etc. is used suitably.
In the method (a), the adhesion force is lowered due to the influence of ultraviolet rays, rain winds, etc. over a long period of time, or in the worst case, it may be peeled off. Can be replaced.
In the method (b), it is not easy and practically impossible to replace the laminate of the surface layer, but instead, the change with time of the adhesive force is small compared to the method (a).
Based on the above characteristics, a method suitable for each application may be used.

  As the adhesive material (a), for example, acrylic, polyurethane, silicone, olefin (including copolymer), rosin, terpene, and the like are generally used. In addition, as the adhesive layer (b), various materials such as acrylic, polyester, polyurethane, and epoxy can be used. Generally, a two-component curable polyurethane having a high coating cohesive force is used. Often, a system adhesive is used.

  Further, as a method for laminating these pressure-sensitive adhesive materials and adhesive materials, there are a method using a coating technique typified by a gravure coating method and a method using a laminating technique such as thermal lamination, extrusion lamination, dry lamination, and sand lamination. Used mainly. The coating and laminating may be carried out first on either the printed material side or the transparent polyolefin layer, and, of course, may be carried out simultaneously like sand lamination.

  Moreover, you may give an uneven | corrugated pattern (not shown) to the transparent polyolefin resin layer 2 in order to provide designability. In that case, once the transparent polyolefin resin layer 2 is formed into a sheet by various methods, a method of forming a concavo-convex pattern by hot pressure, or a method of providing a concavo-convex pattern on a cooling roll and forming a concavo-convex pattern simultaneously with extrusion sheet molding There is. Furthermore, it is possible to embed printing ink or resin in the recess 2a to improve the design and weather resistance.

As an effective use of the laminate obtained as described above, a use as a print protective layer of a decorative sheet can be mentioned. In the case of this application, the concavo-convex pattern improves the design feeling of the decorative sheet and can give a more natural texture.
Hereinafter, the case where the laminated body by this Embodiment is used for a decorative sheet is demonstrated according to drawing of FIG. FIG. 2 is an example of a side cross-sectional view when the laminate according to the present embodiment is used for a decorative sheet.
The laminated sheet composed of the hard coat layer 1 and the transparent polyolefin resin layer 2 is bonded to the base material layer 5 provided with the printed pattern layer 4 and the primer layer 6 through the adhesive layer 3 to thereby obtain the decorative sheet of this example. Composed. However, it is not necessarily limited to this configuration.

The base layer 5 is a paper such as thin paper, titanium paper, resin-impregnated paper, polyethylene, polypropylene, polybutylene, polystyrene, polycarbonate, polyester, polyamide, ethylene-vinyl acetate copolymer, polyvinyl alcohol, acrylic or other synthetic resin, or , Foams of these synthetic resins, ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer rubber, styrene-butadiene copolymer rubber, styrene-isoprene-styrene block copolymer rubber, styrene-butadiene-styrene block copolymer rubber It can be arbitrarily selected from rubbers such as polyurethane, organic or inorganic nonwoven fabrics, synthetic paper, metal foils such as aluminum, iron, gold and silver.
In addition, a pigment or the like can be added to provide concealability.

  The binder of the printed pattern layer 4 may be appropriately selected from nitrified cotton, cellulose, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, polyurethane, acrylic, polyester and the like alone or each modified product. These are aqueous, solvent-based, and emulsion-based, and can be arbitrarily selected from a one-component type and a two-component type using a curing agent. Further, the ink can be cured by irradiation with active energy rays such as ultraviolet rays and electron beams. However, in the case of coloring, the electron beam curing may be more effective in the thickness direction than the ultraviolet curing.

  Examples of the method for providing the printed pattern layer 4 include gravure printing, offset printing, screen printing, flexographic printing, electrostatic printing, and ink jet printing. Further, when a concealing layer is provided, a comma coater, knife coater, lip coater, metal vapor deposition, sputtering method or the like may be used.

  In addition, the primer layer 6 provided in the back surface of the base material layer 5 in FIG. 2 is used when the adhesiveness between the decorative sheet and the base material for decorative board such as wood is insufficient. Even if there is no, it is not particularly necessary when the adhesion is sufficient.

Hereinafter, specific examples of the present embodiment and effects thereof will be described.
<Example 1>
0.5 parts by weight of a benzotriazole ultraviolet absorber (Ciba Specialty Chemicals Co .: Tinuvin 326) and a phenolic antioxidant (Ciba Specialty Chemicals Co., Ltd.) with respect to a transparent homotype polypropylene resin (Prime Polymer Co., Ltd .: Prime PP) Company: Irganox 1010) 0.3 parts by weight and hindered amine light stabilizer (Ciba Specialty Chemicals Co., Ltd .: Kima Soap 944) 0.5 parts by weight of resin are added from an extruder using a casting method. Melt extrusion was performed, and corona treatment was performed on both surfaces thereof to obtain a transparent resin sheet having a thickness of about 80 μm.
On the outermost surface of this sheet, 5 parts by weight of a hydroxyphenyltriazine-based ultraviolet absorber (Ciba Specialty Chemicals: Tinuvin 400) and a hindered amine light stabilizer (Ciba Specialty Chemicals, Inc.) containing a hydroxyl group in the chemical structure. : An isocyanate curable urethane-modified acrylic resin containing 5 parts by weight of tinuvin 152 (manufactured by Dainippon Ink & Chemicals, Inc .: UC Clear) by a gravure coating method to provide a hard coat layer, and the laminate of Example 1 Obtained.

<Example 2>
As a light stabilizer in the hard coat layer, 3 parts by weight of a hindered amine light stabilizer containing a hydroxyl group (Ciba Specialty Chemicals: Tinuvin 152) and a hindered amine light stabilizer not containing a hydroxyl group (Ciba Specialty Chemicals: Tinuvin) The laminate of Example 2 was obtained in the same manner as in Example 1 except that 2 parts by weight of 292) was used.

<Example 3>
Using a sheet obtained by molding a resin obtained by adding 6 parts by weight of a titanium oxide pigment to a random polypropylene resin to a thickness of 70 μm by a calendering method, the sheet surface was subjected to corona treatment, and then image ink (Toyo Ink) by gravure printing. A wood grain pattern is applied using a manufacturer (manufactured by Lamister), and a printed layer is prepared by forming a pattern layer.

  An isocyanate curable adhesive (manufactured by Mitsui Takeda Chemical Co., Ltd .: Takelac and Takenate) was applied to the printed sheet at a thickness of 5 μm using a gravure coating method, and the laminate produced in Example 2 was applied on the adhesive. Lamination was performed using a dry laminating method to obtain a decorative sheet of Example 3.

<Comparative Example 1>
A comparative example using the same method as in Example 1 except that 5 parts by weight of a hindered amine light stabilizer not containing a hydroxyl group (manufactured by Ciba Specialty Chemicals: Tinuvin 292) was added as a light stabilizer in the hard coat layer. 1 laminate was obtained.

<Comparative example 2>
A decorative sheet of Comparative Example 2 was obtained in the same manner as in Example 3 except that the laminate produced in Comparative Example 1 was laminated instead of the laminate produced in Example 2.

<Evaluation method>
With respect to the laminates and decorative sheets prepared as described above as examples and comparative examples, they are stored in a weather resistance tester (die plastic metal weather: manufactured by Daipuru Intes Co., Ltd.), and the following (A) to (D) are 1 As a cycle, an 8-cycle weather resistance test was performed.
(A) Temperature 53 ° C, humidity 50%, illuminance 650 W / square m for 20 hours (B) shower spray 30 seconds (light irradiation stopped)
(C) Temperature 30 ° C, humidity 90% for 4 hours (light irradiation stopped)
(D) Shower spray 30 seconds (light irradiation stop)
The evaluation was performed by checking the degree of embrittlement of the laminate by visual inspection (ranking by sensory test) and the adhesion of the hard coat layer by an adhesive tape peeling test.

A table of the evaluation results is shown in FIG.
As apparent from the results of FIG. 3, the hard coat layer using the light stabilizer containing a hydroxyl group (Examples 1 to 3) uses only the light stabilizer not containing the hydroxyl group. It can be seen that the degree of embrittlement is reduced even when the same weather resistance test is performed as compared with the samples (Comparative Examples 1 and 2). This is because the light stabilizer containing a hydroxyl group remained in the hard coat layer at a high rate even during the weather resistance test, whereas the light stabilizer containing no hydroxyl group had moved out of the hard coat layer. It seems that embrittlement of the hard coat layer has appeared relatively remarkably.
Moreover, in the adhesive evaluation of the hard coat layer by the adhesive tape peeling test, the one using only a light stabilizer containing a hydroxyl group (Example 1) has relatively poor adhesion and does not contain a hydroxyl group. The one using only the agent (Comparative Examples 1 and 2) is almost as bad as the one using the light stabilizer containing a hydroxyl group and the light stabilizer not containing the hydroxyl group (Examples 2 to 3) most closely. The result was good.
Conversely, in the case of only the light stabilizer containing a hydroxyl group, the light stabilizer is not sufficiently transferred to the vicinity of the lamination interface, and in the case of only the light stabilizer not containing a hydroxyl group, the migration to the lamination interface is performed. However, since the hard coat layer itself becomes brittle as described above, the adhesion is not so good.

  In contrast to these, a combination of a light stabilizer containing a hydroxyl group and a light stabilizer not containing a hydroxyl group (Examples 2 to 3) is comprehensively judged from the viewpoint of sheet embrittlement and adhesive tape adhesion, The one having the best physical properties and using only a light stabilizer containing a hydroxyl group (Example 1) also has the ability next to the combined system in terms of the appearance of the hard coat layer.

  INDUSTRIAL APPLICABILITY The present invention is used for a marking overlaminate film, a photographic binder, a building interior / exterior, a surface of a joinery, a frame material, a surface material of home appliances, a decorative sheet on a surface layer of a building material such as a flooring.

It is sectional drawing which shows the laminated body by embodiment of this invention. It is sectional drawing which shows the example of the decorative sheet using the laminated body shown in FIG. It is a table | surface which shows the characteristic measurement result of the Example and comparative example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Hard coat layer layer, 2 ... Transparent polyolefin resin layer, 3 ... Adhesive layer, 4 ... Ink layer, 5 ... Base material layer, 6 ... Primer layer.

Claims (10)

A laminate of a transparent polyolefin resin layer containing at least an ultraviolet absorber and a hard coat layer mainly composed of an isocyanate curable resin,
A light stabilizer containing a hydroxyl group in the chemical structure, and a benzotriazole or hydroxyphenyltriazine-based UV absorber in the hard coat layer,
A laminate characterized by the above.   The laminate according to claim 1, wherein the light stabilizer contains 1 to 20 percent by weight.   The laminate according to claim 1, wherein the ultraviolet absorber contains 1 to 10 percent by weight.   The laminate according to claim 1, wherein the hard coat layer contains both a light stabilizer containing a hydroxyl group and a light stabilizer not containing a hydroxyl group in the structural formula.   The laminate according to claim 4, wherein an abundance ratio of the light stabilizer to the light stabilizer is in a range of 20/80 to 80/20. A sheet in which a laminate and a substrate are joined,
The laminate is formed by laminating a transparent polyolefin resin layer containing at least an ultraviolet absorber and a hard coat layer mainly composed of an isocyanate curable resin,
A light stabilizer containing a hydroxyl group in the chemical structure, and a benzotriazole or hydroxyphenyltriazine-based UV absorber in the hard coat layer,
A sheet characterized by that.   The sheet according to claim 6, wherein the light stabilizer is contained in an amount of 1 to 20 percent by weight.   The sheet according to claim 6, wherein the ultraviolet absorbent is contained in an amount of 1 to 10 percent by weight.   The sheet according to claim 6, wherein the hard coat layer contains both a light stabilizer containing a hydroxyl group and a light stabilizer not containing a hydroxyl group in the structural formula. The sheet according to claim 9, wherein an abundance ratio of the light stabilizer to the light stabilizer is in a range of 20/80 to 80/20.

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