JP7081214B2 - Adhesive cured product, decorative sheet and decorative molded product - Google Patents

Description

The present invention relates to a cured adhesive product suitable for three-dimensional thermoforming, which has excellent elongation and heat resistance. Further, the present invention relates to a decorative sheet containing the adhesive layer and suitable for three-dimensional thermoforming. Further, the present invention relates to a three-dimensional molded body provided with the decorative sheet.

Conventionally, in various fields such as household electric appliances, automobile interior parts, and miscellaneous goods, the surface of a molded body, which is an adherend, is decorated with characters and patterns with white, black, and color inks. It has developed high functionality and design. In particular, for the decoration of a molded product having a complicated surface shape such as a three-dimensional curved surface, a decorative product decorated by laminating a decorative sheet on the surface of an article having a three-dimensional curved surface is used for various purposes. As a decoration method for laminating a decorative sheet, for example, the surface is decorated by laminating and integrating the decorative sheet on the surface at the same time as molding the resin molded product disclosed in Patent Document 1 and the like. An injection molding simultaneous decoration method for obtaining a decorative molded product, or, for example, after introducing a decorative sheet into the molding apparatus disclosed in Patent Document 2, the decorative sheet is softened by heating to soften the decorative sheet. There is known a method using vacuum / pressure molding (TOM molding) for decorating by attaching the above to the surface of a three-dimensional molded body.
As a decorative sheet used for TOM molding, a decorative sheet having a decorative layer (surface layer or surface protective layer), an adhesive layer and the like is known. When a decorative sheet having a decorative layer and an adhesive layer is used, the decorative sheet and the molded body are tightly bonded by utilizing the adhesive force of the adhesive layer or the like. Patent Document 2 discloses a multi-layer sheet having a resin layer (surface layer) and an adhesive layer, and an acrylic adhesive is used as an adhesive constituting the adhesive layer.

In addition, since the decorative sheet of the molded body having a three-dimensional three-dimensional shape is used for mobile, home appliances, notebook PCs, building materials, automobile interior and exterior, etc., it has weather resistance as well as workability and adhesive strength. Durability is required.

Special Publication No. 50-19132 Japanese Unexamined Patent Publication No. 2002-067137 Japanese Unexamined Patent Publication No. 2015-214147

The subject of the present invention is an adhesive cured product having high elongation and heat resistance and excellent adhesiveness and processability, which is suitable for three-dimensional thermoforming, and a decorative sheet and decorative molding using the cured product. To provide the body.

The invention of the present application is as follows.
[1] A cured adhesive product obtained by curing a polyurethane-based adhesive, wherein the elongation stress when the tensile elongation is 300% is 1 MPa or more and 12 MPa or less.

[2] The cured adhesive product according to [1], which has a breaking elongation of 400% or more.

[4] The polyurethane-based adhesive contains a main agent and a curing agent, the main agent contains a polyol composed of a polyether polyurethane polyol and a polyester polyurethane polyol, and the curing agent contains a polyisocyanate [1] to [ 3] The cured adhesive product according to any one of the following items.

[5] The cured adhesive according to [4], wherein the main agent further contains a bisphenol type epoxy resin.

[6] A decorative sheet having a base material layer and an adhesive layer, or a base material layer, a decorative layer, and an adhesive layer in this order, and the adhesive layers are [1] to [5]. ] A decorative sheet made of the cured adhesive according to any one of the items.

[7] The decorative sheet according to [6], wherein the adhesive layer has a film thickness of 2 to 20 μm.

[8] The base material layer is a layer formed from at least one selected from the group consisting of an acrylonitrile-butadiene-styrene copolymer resin, an acrylic resin, a polycarbonate resin, a polyethylene terephthalate resin, and a polyvinyl chloride resin. The decorative sheet according to [6] or [7].

[9] A decorative molded body in which the decorative sheet according to any one of [6] to [8] is laminated on a three-dimensional adherend via the adhesive layer.

INDUSTRIAL APPLICABILITY According to the present invention, an adhesive cured product having high elongation and heat resistance and excellent adhesiveness and processability, which is suitable for three-dimensional thermoforming, and a decorative sheet and a decorative molded product using the cured product can be obtained. Can be provided.

FIG. 1 is a cross-sectional view illustrating one form of the decorative sheet of the present invention. FIG. 2 is a cross-sectional view illustrating another form of the decorative sheet of the present invention. FIG. 3 is a cross-sectional view illustrating one form of the three-dimensional adherend molded product of the present invention. FIG. 4 is a cross-sectional view illustrating one form of the decorative molded product of the present invention.

Hereinafter, the present invention will be described. The description of the constituent elements described below may be based on typical embodiments and specific examples, but the present invention is not limited to such embodiments. The cured adhesive product of the present invention is a reaction-curing adhesive cured product obtained by curing a polyurethane-based adhesive, and is characterized in that the elongation stress when the tensile elongation is 300% is 1 MPa or more and 12 MPa or less. do. By using a reaction-curing adhesive cured product having good elongation, it is possible to achieve both excellent elongation and heat resistance. By using this adhesive cured product, it is possible to obtain a decorative sheet which is excellent in adhesiveness and processability and which is particularly suitable for three-dimensional thermoforming, and a decorative molded body using the decorative sheet.

<Hardened adhesive>
As described above, the cured adhesive product of the present invention is a reaction-curing adhesive cured product obtained by curing a polyurethane-based adhesive, and has an elongation stress of 1 MPa or more and 12 MPa or less when the tensile elongation is 300%. ..

<Polyurethane adhesive>
In the present invention, the polyurethane-based adhesive is not particularly limited, and conventionally known one-component curing type and two-component curing type adhesives can be used. As the two-component curable polyurethane adhesive, a two-component curable polyurethane adhesive using a main agent and a curing agent can be preferably used. The main agent is preferably a polyol main agent, and the curing agent is preferably a polyisocyanate curing agent.

[Polyol main agent]
Polyol main agents are classified into ether type and ester type according to the type of polyol used, and in order to achieve both heat resistance and coatability with the development of adhesive strength, other components may be added or the molecular weight may be optimized. Used.

(Ether-based main agent)
As the ether-based main agent, a polyether polyurethane polyol having a molecular weight of about 500 to 3,000 and having a chain extension reaction with an organic diisocyanate and having a molecular weight of several thousand to several tens of thousands is used as the main agent. Since it is an ether backbone, it has a low viscosity and is excellent in high-speed coatability, but it has a poor initial adhesion due to its low cohesive force.

As the ether-based main agent, a specific polyether polyurethane polyol is preferable, and one containing a bisphenol A type epoxy resin is preferable as described later.

The polyether polyurethane polyol has an equivalent ratio (NCO / OH) of 0.7 or more and less than 1 in the reaction between the polyalkylene glycol and the alkanediol monomer having a repeating unit having 3 or 4 carbon atoms and the organic diisocyanate. The weight average molecular weight thereof is 20,000 to 70,000 and the urethane bond equivalent is 320 to 600 g / eq, and the bisphenol A type epoxy resin has a number average molecular weight of 400 to 5, It is 000 and is preferably solid or semi-solid at room temperature.

(Polyalkylene glycol)
Examples of the polyalkylene glycol used for the synthesis of the above-mentioned polyether polyurethane polyol include polytrimethylene glycol and polypropylene glycol having 3 carbon atoms in the repeating unit, and all having 4 carbon atoms in the repeating unit. Examples thereof include polytetramethylene glycol and polybutylene glycol. Among these, polyalkylene glycol containing at least one of polytetramethylene glycol and polypropylene glycol is preferably used, and more preferably polyalkylene glycol containing polytetramethylene glycol. This is because polytetramethylene glycol has particularly high water resistance, has appropriate crystallinity, and exhibits high moisture and heat resistance. Therefore, the adhesive composition containing a polyether polyurethane polyol having a polytetramethylene glycol structure as a repeating unit as a main agent can be suitably used for producing a laminate used particularly outdoors.

(Alkanediol monomer)
The alkanediol monomer used for the synthesis of the above-mentioned polyether polyurethane polyol preferably has a carbon number in the range of about 2 to 9, and more preferably in the range of about 2 to 6. As a result, the molecular weight of the alkanediol monomer becomes appropriate, so that the urethane bond density forming the hard segment in the polyether polyurethane polyol can be relatively high. Therefore, a high cohesive force can be obtained in the prepared adhesive composition.

Examples of such alkanediol monomers include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 3-methyl-1,5-pentanediol, 1,4-butanediol, neopentyl glycol, and 1,6-. Hexadiol, 2-methyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,9-nonanediol, etc. Listed. One of these or any two or more of them can be used in combination.

(Organic diisocyanate)
Examples of the organic diisocyanate used for the synthesis of the polyether polyurethane polyol include diphenylmethane diisocyanate, tolylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, xylylene diisocyanate, and tetramethylxylylene diisocyanate. Examples thereof include lysine diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, methylcyclohexylene diisocyanate, isopropyridene dicyclohexyl-4,4'-diisocyanate, and derivatives thereof, and one of them or Any two or more kinds can be used in combination.

Examples of the derivative include polyurethane diisocyanate obtained by reacting the above organic diisocyanate with a polyhydric alcohol. Further, as the polyhydric alcohol, alkanediol or the like mentioned as a raw material for synthesizing the above-mentioned polyether polyurethane polyol can be used.

Among these, as the organic diisocyanate, it is preferable to use an aliphatic or alicyclic diisocyanate in which an isocyanate group is not directly bonded to an aromatic ring, or a derivative thereof. Aliphatic or alicyclic diisocyanates are difficult to multimerize (for example, dimerize) even when irradiated with light such as ultraviolet rays. Therefore, even if the laminate produced by using the adhesive composition is left outdoors for a long period of time, it is preferable to prevent the cured product of the adhesive composition from discoloring (discoloring to yellow) over time. Can be done.

Further, as the ether-based main agent, in addition to the polyether polyurethane polyol and the bisphenol A type epoxy resin, a known additive for an adhesive may be contained. Examples of such additives include silane coupling agents, reaction accelerators and the like. When the main agent contains a silane coupling agent, the adhesive strength of the adhesive composition to a substrate composed of a metal material can be improved, and when the main agent contains a reaction accelerator, the adhesive composition can be improved. The aging time (time required for curing) can be shortened.

Examples of the silane coupling agent include vinyltriethoxysilane, trialkoxysilane having a vinyl group such as vinyltriethoxysilane, 3-aminopropyltriethoxysilane, and N- (2-aminoethyl) 3-aminopropyltri. Trialkoxysilanes with amino groups such as methoxysilane, 3-glycidoxypropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, etc. Examples thereof include trialkoxysilane having a glycidyl group, and one of these or any two or more thereof can be used in combination.

Further, as the reaction accelerator, for example, a metal-based catalyst such as dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin dimarate, 1,8-diaza-bicyclo (5,4,0) undecene-7. , 1,5-Diazabicyclo (4,3,0) Nonen-5,6-dibutylamino-1,8-Diazabicyclo (5,4,0) Undecene-7, such as tertiary amines, triethanolamine, etc. Examples thereof include reactive tertiary amines, and one of these or any two or more thereof can be used in combination.

For the purpose of improving the appearance of the coating film, a known leveling agent or defoaming agent may be added to the main agent.

Examples of the leveling agent include polyether-modified polydimethylsiloxane, polyester-modified polydimethylsiloxane, aralkyl-modified polymethylalkylsiloxane, polyester-modified hydroxyl group-containing polydimethylsiloxane, polyether ester-modified hydroxyl group-containing polydimethylsiloxane, and acrylic copolymer. , Methacrylic copolymers, polyether-modified polymethylalkylsiloxanes, acrylic acid alkyl ester copolymers, methacrylic acid alkyl ester copolymers, lecithin and the like.

Examples of the defoaming agent include known ones such as a silicone resin, a silicone solution, and a copolymer of an alkyl vinyl ether, an acrylic acid alkyl ester, and a methacrylic acid alkyl ester.

(Ester-based main agent)
The ester-based main agent is a case where polyesters having a molecular weight of about 1,000 to 3,000 are subjected to a chain extension reaction with diisocyanate to use a polyester polyurethane polyol having a molecular weight of several thousand to tens of thousands as a main agent, and a case where the molecular weight is increased. Thousands to tens of thousands of polyester polyols may be used as the main ingredient. Since the ester main agent system is hydrolyzable and has a high viscosity, it is inferior in high-speed coating property, but has a larger cohesive force than the ether main agent system and is excellent in initial adhesion, heat resistance, chemical resistance and the like.

The polyester polyol and / or the polyester polyurethane polyol includes a polyester polyol obtained by combining an aromatic dibasic acid, an aliphatic dibasic acid having a certain number of carbon atoms or more, and an aliphatic polyhydric alcohol having a certain number of carbon atoms or more. Alternatively, an ester-based main agent composed of a polyester polyurethane polyol is suitable, and is more suitable when used in combination with a polyisocyanate containing a certain amount of isocyanurate, which will be described later, as a curing agent.

When the polyester polyol and / or the polyester polyurethane polyol is used as the main agent, the hydrolysis resistance of the polyol can be enhanced and the decrease in adhesive strength with time during outdoor exposure can be suppressed. In addition, the polyisocyanate, which is a curing agent, contains an isocyanurate skeleton with high heat resistance, which increases the crosslink density and suppresses the swelling of the resin at high temperatures to suppress the infiltration of water into the resin, resulting in an adhesive. The moisture and heat resistance of the cured film can be improved.

Examples of the dibasic acid and its ester compound constituting the polyester polyol and / or the polyester polyurethane polyol include isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, phthalic anhydride, adipic acid, azelaic acid, sebacic acid, succinic acid and glutaric acid. , Phthalic anhydride, hexahydrophthalic anhydride, maleic anhydride, phthalic anhydride and ester compounds thereof can be exemplified. These can be used in combination as appropriate, but the aromatic dibasic acid is 40 to 80 mol% and the aliphatic dibasic acid having 9 or more carbon atoms is 20 to 60 mol% with respect to the total amount of dibasic acid. use. If the amount of aromatic dibasic acid is less than 40 mol%, sufficient heat resistance and viscoelasticity may not be obtained, and if it exceeds 80 mol%, the adhesive strength may be lowered. Further, when the aliphatic dibasic acid is composed of a compound having 8 or less carbon atoms, or when the aliphatic dibasic acid having 9 or more carbon atoms is less than 20 mol%, the degree of ester bond of the polyol increases and hydrolysis is performed. The decomposition base point increases, which may adversely affect long-term moisture resistance.

Among the above exemplified compounds, as the aromatic dibasic acid, terephthalic acid, dimethyl terephthalate, isophthalic acid, and phthalic anhydride are preferable from the viewpoint of reactivity in the transesterification reaction. As the aliphatic dibasic acid having 9 or more carbon atoms, azelaic acid having 9 carbon atoms and sebacic acid having 10 carbon atoms are preferable from the viewpoint of having high lipophilicity and hydrophobicity and suppressing water absorption to the polymer. Aliphatic dibasic acids having 11 or more carbon atoms have a strong aromatic odor, so it is preferable to consider the processing work environment.

Specific examples of polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,6-hexanediol, neopentyl glycol, 1,4-butylene glycol, and 1,4-cyclohexanedimethanol. , Trimethylol propane, glycerin, 1,9-nanonndiol, 3-methyl-1,5-pentanediol and the like. These can be used alone or in two or more kinds, but the aliphatic polyhydric alcohol having 5 or more carbon atoms is used at a ratio of 20 mol% or more with respect to the total amount of the polyhydric alcohol. If the aliphatic polyhydric alcohol is composed of an alcohol having 4 or less carbon atoms, or if the proportion of the aliphatic polyhydric alcohol having 5 or more carbon atoms is less than 20 mol%, the degree of ester bond of the polyol increases and hydrolysis is performed. The base point increases, which may affect long-term moisture resistance.

Among the above-exemplified compounds, neopentyl glycol having 5 carbon atoms and 3-methyl-1,5-having 6 carbon atoms having a side chain and improving dissolution stability are used as lipophilic polyhydric alcohols having 5 or more carbon atoms. Pentanediol and 1,6-hexanediol having high lipophilicity and hydrophobicity and suppressing water absorption into the polymer are preferable.

The weight average molecular weight of the polyester polyol is preferably 10,000 or more from the viewpoint of ensuring cohesive force and adhesive strength, and from the viewpoint of resin solubility, viscosity and adhesive coatability (handleability). It is preferably 150,000 or less, and more preferably 10,000 to 100,000.

The organic diisocyanate used for synthesizing the polyester polyurethane polyol by reacting with the polyester polyol is not particularly limited, and the above-mentioned organic diisocyanate can be used alone or in combination of two or more. Among them, in the case of outdoor use, it is preferable to use an aliphatic or alicyclic isocyanate compound for the urethane crosslinked portion for the purpose of reducing yellowing over time.

Further, by using the polyester polyol in urethane form, the degree of ester bond of the polyol itself (described later) can be lowered, and as a result, the starting point of hydrolysis can be reduced and the moisture and heat resistance can be improved.

The weight average molecular weight of the polyester polyurethane polyol is preferably 10,000 to 100,000, more preferably 10,000 to 70,000 for the same reason as the polyester polyol.

Although the above polyester polyol and polyester polyurethane polyol can be used individually as the ester-based main agent, it is preferable to use them in combination from the viewpoint of balancing adhesive strength and moisture resistance. In that case, the mixing ratio of the polyester polyol and the polyester polyurethane polyol is not particularly limited, but when a polyester polyol having a high cohesive force and a high stretchability and a weight average molecular weight of 70,000 or more is used to improve the adhesive strength, the adhesive strength is improved. It is preferable to use this polyester polyol in an amount of 60 to 80% by mass based on the total amount of the ester-based main agent. In this case, since the polyester polyol has a large weight average molecular weight and a high viscosity, it is necessary to suppress the weight average molecular weight of the polyester polyurethane polyol used in combination to 40,000 or less and adjust the viscosity as an adhesive. Is preferable.

Further, when the ratio of the ester bond due to the reaction between the carboxyl group and the hydroxyl group (the reaction ratio between the carboxyl group and the hydroxyl group is 1: 1) in this ester-based main agent is expressed as the degree of ester bond (mol / 100 g) in the molecule. It is desirable to design so that it is less than 1. That is, according to the findings of the present inventors, by setting the degree of ester bond to less than 1, the ratio of ester bond is reduced to improve hydrolysis resistance, and deterioration of adhesive strength over time is further suppressed for a long period of time. Moisture and heat resistance can be improved.

For example, by selecting a dibasic acid having a large molecular weight (having a large number of carbon atoms) among the polybasic acids, the degree of ester bond in the unit weight (in 100 g) can be reduced. Preferred are aliphatic dibasic acids having 9 or more carbon atoms, and examples thereof include azelaic acid having 9 carbon atoms and sebacic acid having 10 carbon atoms. However, when an aliphatic dibasic acid having about 15 or more carbon atoms is used, the proportion of the aliphatic carbon chain which is a soft segment in the adhesive tends to be large, and the heat resistance of the adhesive tends to be low. In addition, it is also necessary to design in consideration of heat resistance.

Furthermore, by selecting a polyhydric alcohol having a large molecular weight (having a large number of carbon atoms), the degree of ester binding in the unit weight (in 100 g) of the ester-based main agent can be further reduced. Preferred are aliphatic polyhydric alcohols having 5 or more carbon atoms, and examples thereof include neopentyl glycol having 5 carbon atoms, 3-methyl-1,5-pentanediol having 6 carbon atoms and 1,6-hexanediol. Be done. Many linear polyhydric alcohols with a large number of carbon atoms are hydrophobic, and by selecting these, the effect of lowering the hydrophilicity of the molecular chain can be expected. However, when an aliphatic polyhydric alcohol having about 10 or more carbon atoms is used, it is necessary to design in consideration of heat resistance in the same manner as described above.

In particular, considering both the basic performance as an industrial adhesive, for example, the adhesive strength at room temperature and the adhesive strength at high temperature (80 to 150 ° C., etc.), the ester bond degree of the ester-based main agent is 0.75 to 0. A range of .99 is preferred. The fact that the degree of ester bond is 0.75 or more means that the ratio of aromatic dibasic acid, which is a component responsible for heat resistance, in the dibasic acid component is appropriate, and the molecular weight of the polyhydric alcohol is also appropriate. Is that.

In addition to the polyester polyol and / or the polyester polyurethane polyol, the ester-based main agent may contain any component as long as the effect of the present invention is not impaired. The polyol component in the ester-based main agent may contain a polyol other than the polyester polyol and / or the polyester polyurethane polyol, but it is preferable that 90% by mass or more of the polyol component is the polyester polyol and / or the polyester polyurethane polyol. ..

(Epoxy resin)
Further, from the viewpoint of hydrolysis resistance, these main agents are preferably further contained with an epoxy resin, and it is expected that the epoxy group reacts with the carboxyl group generated by the hydrolysis of the ester bond to control the decrease in molecular weight. To. In that case, from the viewpoint of maintaining shear strength, it is preferable to blend an aromatic epoxy resin instead of an aliphatic epoxy resin. Among them, it is preferable to contain a bisphenol type epoxy resin such as a bisphenol A type epoxy resin and a bisphenol F type epoxy resin. Since the bisphenol type epoxy resin has hydrophobicity due to the bisphenol skeleton, it is expected to have an effect of suppressing the hydrolysis of the ester bond. These epoxy resins can be used alone or in any combination of two or more.

Further, from the viewpoint of adjusting the heat resistance / viscoelasticity of the adhesive cured film and adjusting the solution viscosity, a bisphenol type epoxy resin having a number average molecular weight of 1,000 to 3,000 is preferable. If the number average molecular weight is less than 1,000, sufficient heat resistance may not be obtained, while if the number average molecular weight exceeds 3,000, the viscoelasticity as an adhesive may be impaired. be. Further, when a high molecular weight polyol is used, the low molecular weight epoxy resin has the effect of lowering the viscosity of the adhesive solution and improving the coating suitability, but the number average molecular weight is 3,000. If it exceeds, the effect of lowering the solution viscosity becomes small.

When the epoxy resin is blended with the ester-based main agent, the blending amount is preferably 50% by mass or less with respect to the total amount of the main agent from the viewpoint of adjusting the viscoelasticity of the adhesive cured film. A more preferable range is 20 to 40% by mass in consideration of the adhesive strength.

(Other additives)
Further, the ester-based main agent may contain a known additive for an adhesive in addition to the polyester polyol and / or the polyester polyurethane polyol and the epoxy resin. Examples of such an additive include a silane coupling agent, a reaction accelerator, a leveling agent, a defoaming agent, and the like, which are the same as the additives used in the above-mentioned ether-based main agent.

The main agent of the present invention preferably contains at least one polyol selected from the group consisting of a polyether polyurethane polyol, a polyester polyol and a polyester polyurethane polyol, and more preferably selected from the group consisting of a polyether polyurethane polyol and a polyester polyurethane polyol. Contains at least one polyol. Further, more preferably, the main agent further contains a bisphenol type epoxy resin.

[Curing agent]
As the curing agent of the present invention, a conventionally known curing agent can be used, preferably a polyisocyanate, and more preferably a polyfunctional polyisocyanate. The curing agent may be used alone or in combination of any two or more kinds.

(Polyfunctional polyisocyanate)
Examples of the polyfunctional polyisocyanate include a low molecular weight polyisocyanate, a polyurethane isocyanate (adduct form) obtained by reacting a low molecular weight polyisocyanate with water or a polyhydric alcohol, a biuret form or an allophanate form of the polyurethane isocyanate, and a low molecular weight. Examples thereof include uretdione (dimer) or isocyanurate (trimer) of isocyanate.

Examples of the low molecular weight polyisocyanate include those similar to those described as organic diisocyanates, and one of these or any two or more of them can be used in combination. Further, examples of the polyhydric alcohol to react with these low molecular weight polyisocyanates when obtaining a polyurethane isocyanate (adduct) include trifunctional or higher functional polyhydric alcohols such as trimethylolpropane and sorbitol, and the above-mentioned polyether. Examples thereof include alcoholic diols mentioned as raw materials for synthesizing polyurethane polyols.

Here, the polyfunctional polyisocyanate is roughly classified into an aromatic polyfunctional polyisocyanate and an aliphatic or alicyclic polyfunctional polyisocyanate, and it is preferable to use an aliphatic or alicyclic polyfunctional polyisocyanate. Examples of the aliphatic include hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI), butene diisocyanate, 1,3-butadiene-1,4-diisocyanate, and diisocyanates such as octamethylene diisocyanate. Examples of the alicyclic polyfunctional polyisocyanate include isophorone diisocyanate (IPDI), hydrogenated diphenylmethane diisocyanate (hydrogenated MDI), hydrogenated xylene diisocyanate (hydrogenated XDI) cyclohexane diisocyanate, methylcyclohexane diisocyanate, and dicyclohexylmethane diisocyanate. Kind can be exemplified. Xylene diisocyanate (XDI) and tetramethylxylylene diisocyanate (TMXDI), which have an aromatic ring but the isocyanate group is not directly bonded to the aromatic ring, can also be used in the present invention as belonging to the aliphatic diisocyanate.
The polyisocyanate of the present invention is preferably an alicyclic polyfunctional polyisocyanate, and more preferably an isophorone diisocyanate.

Since the aliphatic or alicyclic polyfunctional polyisocyanate does not have an aromatic ring in its structure, it is difficult to multimerize (for example, dimerize) even when irradiated with light such as ultraviolet rays. Therefore, even if the cured adhesive product of the present invention, and the decorative sheet and the decorative molded product using the cured adhesive product are left outdoors for a long period of time, the cured adhesive product discolors over time (yellow). It can be suitably prevented from changing).

Further, the polyfunctional polyisocyanate preferably has at least an isocyanurate structure. Since the isocyanurate structure has high heat resistance and hydrophobicity, the adhesive cured product can exhibit moist heat resistance for a longer period of time by using a curing agent having an isocyanurate structure. The blending amount (content) of the polyfunctional polyisocyanate having an isocyanurate structure is preferably 50 to 100% by mass, more preferably 60 to 100% by mass, based on the total amount of the curing agent. By setting the blending amount of the polyfunctional polyisocyanate having an isocyanurate structure in the curing agent within the above range, the moisture and heat resistance of the cured adhesive can be further improved.

As a specific example of the polyfunctional polyisocyanate having an isocyanurate structure, isocyanurate of 3-isocyanatomethyl-3,5,5-trimethylcyclohexylisocyanate (hereinafter referred to as "isophorone diisocyanate") which is an alicyclic diisocyanate. , Isocyanurate of hexamethylene diisocyanate which is an aliphatic diisocyanate and the like. These curing agents are preferable because they have a long pot life (pot life) after being mixed with the polyol main agent and have good stability (solution stability) of the adhesive composition. Among these, isophorone diisocyanate isocyanurate is more preferably used from the viewpoint of heat resistance.

[Adhesive adjustment]
The blending amount (content) of the curing agent is preferably 3 to 20 parts by mass, and more preferably 7 to 18 parts by mass with respect to the total amount of the main agent. By setting the blending amount of the curing agent and the main agent within the above range, the initial cohesive force of the cured adhesive can be improved, and the decorative sheet and the decorative molded body made of the cured adhesive can be used outdoors. Even when the adhesive is left for a long period of time, it is possible to preferably prevent the peeling strength of the cured adhesive from being lowered.

The poylurethane adhesive of the present invention can also be used as an organic solvent solution (varnish) by containing a known organic solvent. The organic solvent is not particularly limited, and examples thereof include an ester solvent such as ethyl acetate and butyl acetate, a ketone solvent such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, and one of these or any two of them. Seeds and above can be used in combination.

The cured adhesive of the present invention has a specific elongation stress, preferably a specific breaking strength, a specific breaking elongation and a specific storage elastic modulus (Er), which are the types and amounts of the main agent and the curing agent. Can be adjusted to the specific range by appropriately adjusting. In order to make the elongation stress at a tensile elongation of 300% 1 MPa or more and 12 MPa or less, the blending ratio of the main agent and the curing agent [main agent / curing agent (mass ratio)] is preferably 100/4 to 100/22. Yes, more preferably 100/10 to 100/20.

For example, by using a polyol composed of a polyester polyester polyol and a polyester polyurethane polyol as compared with a polyether polyurethane polyol, or by increasing the weight average molecular weight of the polyol, the elongation stress and storage elastic modulus (Er) of the cured adhesive product are increased. Can be designed high.

[Adhesive cured product]
The cured adhesive product of the present invention exhibits excellent thermoformability when the elongation stress when the tensile elongation is 300% is 1 MPa or more and 12 MPa or less, preferably 1.3 MPa or more and 8 MPa or less. .. In particular, when the elongation at break is 400% or more, preferably 500% or more, more preferably 600% or more, the three-dimensional molded body has complicated irregularities when the decorative sheet is heated and stretched and bonded to the molded body. It is possible to obtain a decorative molded body having an excellent appearance by following the shape of the above .

<Decorative sheet>
Since the decorative sheet of the present invention uses a cured adhesive having a high elongation rate, the film thickness is significantly reduced as compared with the thermoplastic resin used as the adhesive layer of the conventionally known decorative sheet. Can be done. Specifically, it can be 20 μm or less, which leads to weight reduction. Further, heat resistance can be imparted.

The decorative sheet of the present invention comprises a base material layer and an adhesive layer, or a base material layer, a decorative layer and an adhesive layer in this order, and the base material layer may have decorativeness. .. A laminated sheet having at least one base material layer, a decorative layer, and an adhesive layer is preferable, and a release layer is further provided on the adhesive layer for the purpose of protecting the adhesive layer of the decorative sheet. You may. In that case, it becomes a base material layer / adhesive layer / peeling layer, or a base material layer / decorative layer / adhesive layer / peeling layer. The decorative sheet of the present invention may have the above layers in this order, and may have another layer between the layers. The adhesive layer of the present invention uses a cured adhesive having a high elongation rate, and is particularly suitable for use in a three-dimensional molded body.

[Adhesive layer]
The adhesive layer used for the decorative sheet of the present invention is made of the cured adhesive having a elongation stress of 1 MPa or more and 12 MPa or less when the tensile elongation is 300%.

The adhesive layer can be formed by a conventionally known method, and usually, after being applied to the base material layer, it undergoes a step of drying, laminating (lamination), and aging (curing reaction). The amount of adhesive applied to the base material layer (DRY) can be selected from known conditions, and is preferably 2 to 10 g / m ² as in normal dry lamination. As the coating method, direct gravure coating, reverse coating, reverse gravure coating and the like can be used.

Further, it is preferable that the adhesive layer is subjected to a drying step immediately before the laminating step. The temperature and time of the drying step are preferably, for example, 60 to 100 ° C. for 1 to 20 minutes, and more preferably 70 to 90 ° C. for 5 to 15 minutes. The drying step is preferably performed within 1 hour before the laminating step. The drying step is more preferably performed within 30 minutes before the laminating step, and more preferably within 15 minutes before the laminating step is performed. Further, the adhesive layer is preferably dried in a vacuum dryer. Further, the drying step may be the first drying performed immediately after the adhesive layer is applied, or may be a re-drying for re-drying immediately before laminating separately from the first drying.
The adhesive layer made of a cured adhesive may be a colored layer in which a pigment such as carbon black or titanium oxide or a dye is blended with these adhesives.

[Base material]
The decorative sheet of the present invention has a base material layer. The base material layer is preferably one that can be stretched so as to follow the molded body in the molding step. The material constituting the base material layer is preferably plastic. Examples of the plastic include ABS resin (acrylonitrile-butadiene-styrene copolymer), AS resin (acrylonitrile-styrene copolymer), acrylic resin, polyethylene terephthalate resin, polybutylene terephthalate resin, nylon, polyacetal resin, and polyphenylene oxide resin. , Phenol resin, Julia resin, Melamine resin, Liquid crystal polymer, Polytetrafluoroethylene resin, Polyvinyl chloride resin, Polyfluorinated vinylidene resin, Polysulfone resin, Polyether sulfone resin, Polyacetal resin, Polyether ether ketone resin, Polyphenylene sulfide resin , Polyateimide resin, polyamideimide resin, polycarbonate resin, polyethylene resin, polypropylene resin, polystyrene resin, urethane resin and the like, preferably acrylonitrile-butadiene-styrene copolymer resin, acrylic resin, polycarbonate resin, polyethylene terephthalate. At least one selected from the group consisting of a resin and a polyvinyl chloride resin, and more preferably at least one selected from the group consisting of an acrylonitrile-butadiene-styrene copolymer resin, an acrylic resin, and a polycarbonate resin. It is particularly preferable to use an ABS resin or an acrylic resin.

From the viewpoint of transparency, an acrylic resin is preferable, and a resin obtained by polymerizing a resin composition containing a monomer component having a (meth) acryloyl group as a main component is preferable. The main component of the monomer component is preferably (meth) acrylic acid ester, preferably methyl methacrylate.

The base material layer in the present invention may be colorless or may be colored and have decorative properties. In order to impart decorativeness to the base material layer, a method of adding a known colorant in the decorative layer described later to the resin forming the base material layer and the like can be mentioned, but the present invention is not limited thereto.

The thickness of the base material layer is preferably 25 μm to 300 μm, more preferably 50 μm to 200 μm. When the thickness of the base material layer is within the above range, the processability, shape followability, and handleability are good when the decorative molded product is manufactured by the vacuum forming method.

[Decorative layer]
The decorative layer in the present invention is a layer provided for imparting the design of a decorative sheet, and is a decorative layer for expressing a pattern, characters, a patterned pattern, or the like. Examples of the pattern include wood grain, stone grain, cloth grain, sand grain, geometric pattern, characters, stripe-like and gradation patterns, and the like.

The pattern layer can usually be formed by a known printing method such as gravure printing, offset printing, silk screen printing, transfer printing from a transfer sheet, sublimation transfer printing, and ink jet printing with printing ink. The thickness of the stalk layer can be appropriately adjusted according to the morphology of the stalk.

As the binder of the ink used for forming the pattern layer, chlorination of polyester resin, urethane resin, acrylic resin, vinyl acetate resin, vinyl chloride-vinyl acetate copolymer, cellulose resin, chlorinated polyethylene, chlorinated polypropylene, etc. One type or a mixture of two or more types of a polyolefin resin or the like can be used. As the ink, in addition to the binder made of the above-mentioned various resins, a colorant such as a pigment and a dye, an extender pigment, a solvent, a stabilizer, a plasticizer, a catalyst, a curing agent and the like are appropriately mixed.

Colorants used for the above inks include inorganic pigments such as titanium white, zinc flower, petal pattern, vermilion, ultramarine, cobalt blue titanium yellow, yellow lead, and carbon black, isoindolinone yellow, Hansa yellow A, quinacridon red, and permanent. Organic pigments (or dyes included) such as Red 4R, Phthalocyanine Blue, Induslen Blue RS, and Aniline Black, metal pigments consisting of metal powders such as aluminum and brass, titanium dioxide-coated mica, and foil powders such as basic lead carbonate. It is possible to use one kind or a mixture of two or more kinds of pearl luster (pearl) pigments, fluorescent pigments and the like.

The handle layer may be a metal thin film layer or the like. The metal thin film layer is formed by using a metal such as aluminum, chromium, gold, silver, or copper, and forming a film by a method such as vacuum deposition or sputtering. Alternatively, a combination of these may be used. The metal thin film layer may be provided on the entire surface or may be partially provided in a pattern.

The decorative layer may be a pattern layer on which a concealing layer is further provided. The concealing layer is provided for the purpose of concealing the pattern and coloring of the background (molded body) after laminating the decorative sheet on the decorative molded product. Therefore, the layer structure after laminating on the molded body is preferably (surface side) base material layer / decorative layer (pattern layer / shielding layer) / adhesive layer (molded body side). The shielding layer is usually formed as a solid or partially solid colored layer without a pattern. In some cases, the handle layer also acts as a solid layer (shielding effect), and in this case, it is not necessary to form the shielding layer. The shielding layer can be formed by using an ink containing the same coloring pigment as the above-mentioned pattern layer.

Further, in the present invention, the decorative sheet may be embossed.

[Release layer]
The decorative sheet of the present invention may have a release layer to protect the adhesive layer. The peeling layer may be any as long as it can be easily peeled from the adhesive layer, and conventionally known ones can be used.

In the present invention, as the release layer, it is preferable to use a release sheet provided with a release layer containing a release agent such as a silicone type on one side of a known resin sheet such as a polyester sheet.

[Manufacturing of decorative sheets]
The decorative sheet of the present invention is not particularly limited as long as the decorative sheet has each of the above-mentioned layer configurations, and can be produced by a conventionally known method. For example, a decorative layer coating liquid containing a colorant is applied onto the base material layer to form a decorative layer. Next, an organic solvent solution (varnish) containing the above adhesive is applied onto the decorative layer to form an adhesive layer, and then a release sheet to be a release layer is laminated to form a decorative sheet. To manufacture.

Further, when laminating each layer of the decorative sheet of the present invention, an adhesive layer made of the adhesive of the present invention may be provided between each layer for laminating.

As the coating method of the above-mentioned adhesive, for example, a direct gravure roll coating method, a gravure roll coating method, a kiss coating method, a reverse roll coating method, a fonten method, a transfer roll coating method, or other methods can be applied. The coating amount (DRY) is preferably 0.1 g / m ² to 10 g / m ² , and more preferably 1 g / m ² to 5 g / m ² .

<Decorative molded body>
The decorative molded body of the present invention is obtained by attaching the decorative sheet of the present invention to a part or the entire surface of the surface of the adherend molded body, and the decorative sheet is the adherend molded body via an adhesive layer. It is affixed to.
By using the decorative sheet of the present invention, the decorative molded product of the present invention can exhibit high functionality and design. Hereinafter, the configuration of the decorative molded product of the present invention will be described with reference to the drawings.

FIG. 4 shows a schematic cross-sectional view of an example of the decorative molded product according to the present invention. In the decorative molded body MS shown in FIG. 4, the adherend molded body M and the decorative layer are bonded to each other via an adhesive layer, and a base material layer is further formed on the decorative layer.

[Applied molded product]
The adherend molded body in the present invention is a molded body decorated with the decorative sheet of the present invention, and is, for example, a curved plate material of various materials, a three-dimensional shaped article, or the like. Since the decorative sheet of the present invention is excellent in moldability at the time of decorative molding and adhesion in a high temperature environment, it is possible to increase the productivity of the decorative molded product, and it is also excellent in designability and durability. It is possible to obtain a decorative molded product.

More specifically, various materials include wood fiber plates, metal materials such as iron and aluminum, ceramics such as glass and ceramics, non-cement ceramic materials such as plaster, and non-ceramic ceramics such as ALC (lightweight bubble concrete) plates. Materials, acrylic resin, polyester resin, polystyrene resin, polyolefin resin such as polypropylene, acrylonitrile-butadiene-styrene copolymer (ABS resin), polycarbonate resin, phenol resin, vinyl chloride resin, cellulose resin And resin materials such as rubber.
In the present invention, the shape of the adherend molded body, that is, the shape of the object on which the decorative sheets are laminated is preferably non-planar, and examples thereof include a substantially spherical shape and a concavo-convex shape such as a convex shape. ..

<How to use>
When the three-dimensional molded body is decorated with the decorative sheet of the present invention, it may be performed in the same manner as a conventionally known method, and is not particularly limited. That is, the decorative sheet is crimped and decorated so that the adhesive layer faces the surface of the adherend and the decorative sheet is in close contact with the surface of the adherend. Then, heating is performed to cure the adhesive layer to obtain a decorative molded product. Examples of the molding method under vacuum conditions or reduced pressure conditions include a TOM molding (three-dimensional coating molding) method, and the decorative sheet of the present invention is particularly preferably used in a molding method such as TOM molding.

As described above, the TOM (Three dimension Overlay Method) method is preferably used as the method for producing the decorative molded product of the present invention. In the TOM method, for example, air is sucked into both spaces in the device where the decorative sheet fixed to the fixed frame is divided by a vacuum pump or the like, and the inside of the device is evacuated. At the same time, the decorative sheet is heated with an infrared heater until it reaches a predetermined temperature at which it softens, and at the timing when the decorative sheet is heated and softened, the atmosphere is sent to only one side of the space inside the device to create a vacuum atmosphere. The decorative sheet is firmly adhered to the three-dimensional shape of the molded body, which is the adherend below. If necessary, compressed air pressing from the silicone rubber sheet side may be used in combination. After the decorative sheet is in close contact with the molded body, the silicone rubber sheet is released from the decorative sheet, and then the decorative sheet molded from the fixed frame is removed to obtain a decorative molded product. Vacuum forming is usually carried out at about 80 to 150 ° C., preferably about 110 to 140 ° C.

The decorative molded body obtained by the present invention is not particularly limited, but is, for example, an automobile exterior part such as a bumper, a front under spoiler, a rear under spoiler, a side under skirt, a side garnish, and a door mirror, an instrument panel, a center console, and a door switch panel. Examples thereof include automobile interior parts such as mobile phones, audio products, refrigerators, fan heaters, housings of home appliances such as lighting fixtures, and vanities.

Hereinafter, the present invention will be described based on examples, but the present invention is not limited thereto. In the examples, "parts" and "%" represent "parts by mass" and "% by mass", respectively.

<Polyol synthesis method>
<Synthesis of polyol A>
Polytetramethylene glycol with a number average molecular weight of 2,000 (“PTMG2000SN”, manufactured by Hodogaya Chemical Co., Ltd., hereinafter abbreviated as “PTMG2000”): 74.54 parts and 3-methyl-1,5-pentanediol ( Hereinafter, "MPD" is abbreviated): 6.61 parts and isophorone diisocyanate (hereinafter, abbreviated as "IPDI"): 18.85 parts so as to have an equivalent ratio of 0.91 (NCO / OH). After charging in a synthetic container equipped with a stirrer, these reactions were carried out at 170 ° C. for 2 hours to obtain a polyol. A resin solution having a solid content of 50% obtained by diluting with ethyl acetate was used as a polyol A solution.

<Synthesis of polyol B>
119.5 parts of dimethyl terephthalate, 92.2 parts of ethylene glycol, 72.2 parts of neopentyl glycol, and 0.02 parts of zinc acetate were placed in a reaction can and heated to 160 to 210 ° C. with stirring under a nitrogen stream. , The transesterification reaction was carried out. After distilling 97% of the theoretical amount of methanol, 93.0 parts of isophthalic acid and 130.0 of azelaic acid were charged and heated to 160 to 270 ° C. to carry out an esterification reaction. The reaction can is gradually depressurized to 1 to 2 tolls as it is, and when the acid value becomes 0.8 mgKOH / g or less, the reaction under reduced pressure is stopped, and the polyester polyol having a weight average molecular weight of 80,000 (ester bond degree). 0.93 mol / 100 g) was obtained. A resin solution having a solid content of 50% obtained by diluting with ethyl acetate was used as a polyol B solution.

<Synthesis of polyol C>
94.2 parts of neopentyl glycol, 91.7 parts of 1,6-hexanediol, 37.6 parts of ethylene glycol, 211.5 parts of isophthalic acid, and 122.9 parts of sebacic acid were charged in a reaction can and stirred under a nitrogen stream. While heating to 160 to 250 ° C., an esterification reaction was carried out. The reaction can was gradually depressurized to 1 to 2 tolls as it was, and when the acid value became 1 mgKOH / g or less, the reaction under reduced pressure was stopped to obtain a polyester polyol of the previous stage having a weight average molecular weight of 6,000. .. 22.9 parts of isophorone diisocyanate was gradually added to the obtained polyester polyol, and the mixture was heated and reacted at 100 to 150 ° C. After the reaction for 6 hours, a polyester polyurethane polyol having a weight average molecular weight of 35,000 (ester bond degree 0.79 mol / 100 g) was obtained. A resin solution having a solid content of 50% obtained by diluting with ethyl acetate was used as a polyol C solution.

<Synthesis of polyol D>
A resin solution having a solid content of 50% obtained by heating and mixing 100 parts of polyol B and 40 parts of polyol C at 70 ° C. and diluting with ethyl acetate was used as a polyol D solution.

<Synthesis of polyol E>
A resin solution having a solid content of 50% obtained by heating and mixing 40 parts of polyol B and 100 parts of polyol C at 70 ° C. and diluting with ethyl acetate was used as a polyol E solution.

<Synthesis of polyol F>
72.8 parts of ethylene glycol and 146.0 parts of adipic acid were charged in a reaction can and heated to 160 to 240 ° C. with stirring under a nitrogen stream to carry out an esterification reaction. The reaction can is gradually depressurized to 1 to 2 tolls as it is, and when the acid value becomes 0.8 mgKOH / g or less, the reaction under reduced pressure is stopped, and the polyester polyol having a weight average molecular weight of 35,000 (ester bond degree). 1.16 mol / 100 g) was obtained. A resin solution having a solid content of 50% obtained by diluting with ethyl acetate was used as polyol F.

<Synthesis of polyol G>
Polytetramethylene glycol having a number average molecular weight of 2,000 (“PTG2000SN”, manufactured by Hodogaya Chemical Co., Ltd., hereinafter abbreviated as “PTMG2000”): 73.52 parts and 1,6-hexanediol (hereinafter, “1”. , 6-HD ”): 10.14 parts and isophorone diisocyanate (hereinafter abbreviated as“ IPDI ”): 16.34 parts so as to have an equivalent ratio of 0.91 (NCO / OH). After charging in a synthetic container equipped with a stirrer, these reactions were carried out at 170 ° C. for 2 hours to obtain a polyol. A resin solution having a solid content of 50% obtained by diluting with ethyl acetate was used as a polyol G.

<How to adjust the main agent>
<Preparation of main agent 1 (polyether polyurethane polyol)>
Polyol A solution: 140 parts, a melting point of 78 ° C., a number average molecular weight of 1,200, and a solid bisphenol A type epoxy resin at room temperature ("YD-012", manufactured by Toto Kasei Co., Ltd.): 30 parts and 3 parts of an epoxy group-containing organosilane coupling agent (“KBE403”, manufactured by Shin-Etsu Chemical Co., Ltd., the same applies hereinafter): 3 parts were added. Then, three parts of a heat stabilizer (“Irganox 1010”, manufactured by BASF, the same applies hereinafter): 3 parts are further added thereto, and these are dissolved by mixing while heating at 70 ° C. Obtained a lysate. Next, ethyl acetate was added to this solution to adjust the non-volatile content to 50% to obtain the main agent 1.

<Preparation of main agent 2 (polyester polyurethane polyol)>
Polyol D solution: 140 parts, bisphenol A type epoxy resin (manufactured by Toto Kasei Co., Ltd., YD-012) 30 parts, epoxy group-containing organosilane coupling agent (manufactured by Shinetsu Chemical Industry Co., Ltd., KBE-403) 3 parts Was heated, dissolved, and mixed at 70 ° C., and the resin solution having a solid content of 50% obtained by diluting with ethyl acetate was used as the main agent 2.

<Preparation of main agent 3 (polyester polyurethane polyol)>
Polyol E solution: 140 parts, bisphenol A type epoxy resin (manufactured by Toto Kasei Co., Ltd., YD-012) 30 parts, epoxy group-containing organosilane coupling agent (manufactured by Shinetsu Chemical Industry Co., Ltd., KBE-403) 3 parts Was heated, dissolved and mixed at 70 ° C., and the resin solution having a solid content of 50% obtained by diluting with ethyl acetate was used as the main agent 3.

<How to adjust the curing agent>
<Preparation of curing agent 1>
The isocyanurate form of hexamethylene diisocyanate was diluted with ethyl acetate so that the non-volatile content was 50% to prepare a curing agent 1.

<Preparation of curing agent 2>
A resin solution having a solid content of 50% by diluting a trimer of isophorone diisocyanate with ethyl acetate was used as a curing agent 2.

<Preparation of curing agent 3>
1:60 parts of the curing agent and 40 parts of the curing agent obtained by diluting the adduct of trimethylolpropane hexamethylene diisocyanate with ethyl acetate so that the non-volatile content becomes 50% are mixed at 70 ° C. and non-volatile. The curing agent 3 was prepared by diluting with ethyl acetate so that the portion became 50%.

<Adhesive manufacturing method>
<Adhesives 1-8>
The various main agents and curing agents shown in Table 1 were blended in the mass ratios shown in Table 1 and diluted with ethyl acetate to adjust the solid content to 30% to obtain adhesives 1 to 8.

<Manufacturing of cured adhesive>
[Examples 1 to 6, Comparative Examples 1 and 2]
(Adhesive cured product 1-8)
The obtained adhesive was applied to the unstretched polypropylene (CPP) sheet-treated surface with an applicator so that the coating thickness was 60 μm, air-dried 1 day, and then aged at 60 ° C. for 1 week. Additional aging at 80 ° C. was carried out until the disappearance of the isocyanate group could be confirmed by the IR permeation method to prepare adhesive cured products 1 to 8.

<Evaluation of cured adhesive>
The obtained cured adhesive was evaluated as follows. The results are shown in Table 2.

[Preparation of sample for measuring film physical characteristics]
The cured adhesive was cut into a width of 5 mm and a length of 6 cm to prepare a sample peeled from the untreated CPP. The thickness of each sample was measured. In the case of the tensile test, thick paper was attached to both ends of the measurement length of 2 cm using double-sided tape to reinforce the sample.

[Elongation stress (tensile stress) when tensile elongation is 300%]
Using a testron type tensile tester, perform a tensile test under the conditions of chuck distance: 2 cm, tensile speed: 60 mm / min, and tensile when the 300% elongation stress is F (gf) and sample thickness S (μm). The stress was calculated from the following formula.
300% tensile stress (MPa) = 0.098 × F × 10 ^-3 / 0.5 × S × 10 ^-4
= 0.098 × 20 × F / S

[Elongation at break]
A tensile test was performed using a testron type tensile tester under the conditions of a distance between chucks of 2 cm and a tensile speed of 60 mm / min, and the elongation when the sample was cut (broken) was determined. The tensile elongation was calculated by the following formula.
Tensile elongation (%) = 100 × (L-Lo) / Lo
Lo: Sample length before test L: Sample length at break

<Manufacturing method of decorative sheet>
[Example 7]
(Decorative sheet 1)
ABS sheet (manufactured by Techno Polymer Co., Ltd., VALUETECH NSG400, thickness: 200 μm) is used as the base material layer, and polyester gravure ink VKNT (manufactured by Toyo Ink Co., Ltd.) is used as a decorative layer on one surface thereof. A layer of wood grain pattern printed in three colors and a light brown solid layer were formed by gravure printing, and a decorative layer was provided. Subsequently, the adhesive 1 is applied on the decorative layer by gravure printing so that the coating thickness after drying is 3 μm, and after drying, a release sheet (one side of which is peeled with a silicone-based release agent) is applied to the polyester. A film, film thickness: 38 μm, manufactured by Tohcello Corporation, SP-PET-03) was laminated to obtain a decorative sheet 1.

[Examples 8 to 17, Comparative Examples 3 and 4]
(Decorative sheets 2 to 13)
Decorative sheets 2 to 13 were obtained in the same manner as the decorative sheet 1 except that the type of the adhesive layer, the coating amount, and the type of the base material layer were changed to the contents shown in Table 3.

The abbreviations in Table 3 are shown below.
ABS: Acrylonitrile-butadiene-styrene copolymer resin (Technopolymer, VALUETECH NSG400, thickness: 200 μm)
PMMA: Acrylic resin (manufactured by Mitsubishi Chemical Corporation, Acryprene HBA002P, thickness 125 μm)
PC: Polycarbonate resin (manufactured by Teijin, Panlite PC-2151, thickness 200 μm)
PVC: Polyvinyl chloride resin (manufactured by Achilles, Achilles reddish transparent, thickness 200 μm)
PET: Polyethylene terephthalate resin (manufactured by Toyobo Co., Ltd., Cosmo Shine, thickness 188 μm)

<Manufacturing of decorative molded products>
[Example 18]
(Decorative molded body 1)
ABS molded into a hemispherical shape with a diameter of 120 cm and a thickness of 5 mm on a vertical lift table installed in the lower box in a double-sided vacuum forming device (trade name: NGF-0709, manufactured by Fuse Vacuum Co., Ltd.) consisting of upper and lower boxes. The adherend was set so that the convex surface of the hemisphere was facing upward. After that, the peeling sheet of the obtained decorative sheet 1 is peeled off from the sheet clamp frame in the upper box of the double-sided vacuum forming apparatus, and the adhesive layer of the decorative sheet and the adherend molded body in the lower box are set to face each other. did. Subsequently, the pressure inside the upper and lower boxes is reduced to 1.0 kPa, and the decorative sheet is heated to 130 ° C. using a near-infrared heater to raise the adherend. , The adherend and the decorative sheet were crimped, and then 200 kPa of compressed air was introduced only into the upper box and held for 35 seconds. The upper and lower boxes were opened to atmospheric pressure, and the decorative sheet was vacuum-bonded to obtain a decorative molded body. Then, it was aged at 60 ° C. for 7 days, and the adhesive was cured to obtain a decorative molded product 1 decorated with a decorative sheet.

[Examples 19 to 28, Comparative Examples 5 and 6]
(Decorative molded body 2 to 13)
Decorative molded bodies 2 to 13 were obtained in the same manner as in the decorative molded body 1 except that the types of the decorative sheets were changed to the contents shown in Table 4.

<Evaluation of decorative molded product>
The obtained decorative molded product was evaluated based on the following criteria. The results are shown in Table 4.

[Adhesion evaluation]
A single crosscut of 40 mm × 40 mm is placed in the center of the decorative layer of the hemispherical decorative molded body according to JIS K5600-5-6, and after leaving it at 20 ° C for 24 hours and after leaving it at 80 ° C for 24 hours, another 20 After leaving at ° C for 24 hours, it was confirmed that the cross-cut portion had a gap opening.
Evaluation score (4 or less is unusable level)
10: No peeling at all 8: No peeling at the intersection, slight peeling at the X-cut part 6: There is peeling within 1.5 mm in either direction from the intersection of the X-cut part 4: X-cut There is peeling over 1.5 mm and within 3 mm in either direction from the intersection of the parts 2: Most of the X-cut part with the tape is peeled off 0: Peeling larger than the X-cut part

From these evaluation results, the adhesiveness before and after the heat resistance test was good when the decorative sheet coated with the adhesive layer of the example was used, whereas it was decorated with the adhesive layer of the comparative example. When the sheet was used, it was not good.

The decorative sheet made of the cured adhesive of the present invention has excellent adhesiveness, workability, and heat resistance after molding, and is therefore used for mobile phones, personal computer frames, air conditioners, televisions, refrigerators, and automobile interiors. It can be used not only for decoration but also for harsh applications required for automobile exteriors.

1 Base material layer 2 Decorative layer 3 Adhesive layer 4 Peeling sheet S Decorative sheet M Adhesive molded body MS Decorative molded body

Claims (8)

It is an adhesive cured product obtained by curing a polyurethane-based adhesive, and has an elongation stress of 1 MPa or more and 12 MPa or less when the tensile elongation is 300%.
The polyurethane-based adhesive contains a main agent and a curing agent, and the main agent contains at least one polyol selected from the group consisting of a polyether polyurethane polyol, a polyester polyol, and a polyester polyurethane polyol, and the curing agent comprises. Contains polyisocyanate,
An adhesive cured product in which the main agent further contains an aromatic epoxy resin. The cured adhesive product according to claim 1, wherein the elongation at break is 400% or more. The cured adhesive product according to claim 1 or 2 , wherein the main agent contains at least one polyol selected from the group consisting of a polyether polyurethane polyol and a polyester polyurethane polyol. The cured adhesive product according to any one of claims 1 to 3 , wherein the aromatic epoxy resin contains a bisphenol A type epoxy resin. A decorative sheet comprising a base material layer and an adhesive layer, or a base material layer, a decorative layer, and an adhesive layer in this order, wherein the adhesive layer is any one of claims 1 to 4 . A decorative sheet made of the cured adhesive according to the above. The decorative sheet according to claim 5 , wherein the adhesive layer has a film thickness of 2 to 20 μm. The base material layer is a layer formed from at least one selected from the group consisting of an acrylonitrile-butadiene-styrene copolymer resin, an acrylic resin, a polycarbonate resin, a polyethylene terephthalate resin, and a polyvinyl chloride resin. The decorative sheet according to claim 5 or 6 . A decorative molded body in which the decorative sheet according to any one of claims 5 to 7 is laminated on a three-dimensional adherend via the adhesive layer.

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