JP2011231249A - Aqueous urethane resin dispersion for decorative film and decorative film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a decorative film which does not need an ultraviolet light irradiation step, follows the shape of a substrate, and provides a coating film having little difference among physical properties on various parts of the substrate.SOLUTION: An aqueous urethane resin dispersion for the decorative film contains a urethane resin (U) and a crosslinking agent (L). It is preferable that the urethane resin (U) satisfies following (1) to (5). (1) The content of a terminal amino group in the (U) is 0-0.35 mmol/g based on the weight of the (U). (2) The number-average molecular weight (Mn) of the (U) is 10,000 to 1,000,000. (3) The ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn) is 1.5-3.5. (4) The volume-average particle diameter (Dv) of the (U) is 0.01-1 μm. (5) The elongation at break of the (U) is ≥200%.

Description

  The present invention relates to an aqueous urethane resin dispersion for a decorative film and a decorative film used when decorating a molded product by a film decoration method.

  A molded product such as a metal product, a plastic product, and a wooden product may be subjected to a coating process for forming a coating film on the surface of the molded product for the purpose of imparting durability or design. As a coating method, spray coating and dip coating are mainly used widely. However, spray coating and dip coating methods involve a multi-step process in which the coating process and the drying process are repeated, and therefore the process time becomes long and the process management becomes complicated. There are also environmental problems such as the generation of volatile substances in the painting and drying processes.

  Therefore, as a coating film forming method that replaces the spray coating or the dip coating, a film decoration method for coating an object to be coated using a decorative film in which a plurality of layers are laminated has been proposed (for example, Patent Document 1). And 2). In this film decorating method, the decorating film is coated so as to adhere to the surface of the object to be coated. Therefore, unlike the spray coating method and the dip coating method, a multi-step process is not required for coating, the process time is shortened, and the generation of volatile substances can be suppressed. However, since the conventional decorative film uses an acrylic ultraviolet curable resin for film formation, it requires a step of irradiating with ultraviolet rays after being coated on a molded product, and the curability and economic efficiency of the recess are sufficient. is not.

JP 2000-79796 A JP 2005-255781 A

  The present invention has been made in view of the above problems, and the object of the present invention does not require an ultraviolet irradiation step, follows the shape of the substrate, and has little difference in physical properties of the coating film depending on the portion of the substrate. It is to provide a decorative film.

  As a result of intensive studies to achieve the above object, the present inventors have reached the present invention. That is, this invention dries at least this urethane resin aqueous dispersion for decorative films on the guard film (G) and the urethane resin aqueous dispersion for decorative films containing the urethane resin (U) and the crosslinking agent (L). This is a decorative film having a clear layer (F) and an adhesive layer (A) obtained in this manner.

  By using the decorative film of the present invention, an ultraviolet irradiation step is not required, and a coating film having uniform physical properties can be obtained even when applied to a substrate having irregularities. Moreover, it can extend uniformly following the shape of the substrate and can be decorated with a uniform film thickness.

  The urethane resin aqueous dispersion for a decorative film of the present invention contains a urethane resin (U) and a crosslinking agent (L). Moreover, the decorative film of the present invention forms a clear layer (F) by applying at least the urethane resin aqueous dispersion on the guard film (G), and then forms an adhesive layer (A) thereon. Can be obtained. The clear layer (F) may be a single layer or a plurality of layers having different components. A colored layer containing a colorant can also be provided between the clear layer (F) and the adhesive layer (A).

  After the decorative film of the present invention is set on a substrate and brought into close contact with the substrate by vacuum molding or the like, a molded product decorated by heat treatment is obtained. The guard film (G) may be peeled off before the heat treatment or may be peeled off after the heat treatment. When the decorative film of the present invention is used, since the clear layer (F) has an appropriate elongation at break, it is excellent in followability to the base material when it is brought into close contact with the base material by vacuum molding or the like, and the subsequent heat treatment As a result, the urethane resin (U) in the clear layer (F) reacts with the crosslinking agent (L) to obtain a coating film having high strength and high hardness.

  The urethane resin (U) in the present invention comprises the polyol (a), the polyisocyanate (b), and a compound (c) containing a carboxyl group and an active hydrogen atom as essential components, and if necessary, a hydrophilic group and an active hydrogen atom. It is produced by reacting a compound (d) containing a chain extender (e) and a reaction terminator (f).

Examples of the polyol (a) include a polymer polyol (a1) having a number average molecular weight (hereinafter abbreviated as Mn) of 300 or more and a low molecular polyol (a2) having a Mn of less than 300.
In the present invention, the Mn of the polyol is measured by gel permeation chromatography (GPC) using polyethylene glycol as a standard. However, Mn of the low molecular polyol is a calculated value from the chemical formula.

  Examples of the polymer polyol (a1) having Mn of 300 or more include polyether polyol (a11) and polyester polyol (a12).

  Examples of the polyether polyol (a11) include aliphatic polyether polyols and aromatic ring-containing polyether polyols.

  Examples of the aliphatic polyether polyol include polyoxyethylene polyol [polyethylene glycol (hereinafter abbreviated as PEG), etc.], polyoxypropylene polyol [polypropylene glycol, etc.], polyoxyethylene / propylene polyol, and polytetramethylene ether glycol. Can be mentioned.

  Commercially available products of aliphatic polyether polyols include PTMG1000 [polytetramethylene ether glycol with Mn = 1,000, manufactured by Mitsubishi Chemical Corporation], PTMG2000 [polytetramethylene ether glycol with Mn = 2,000, Mitsubishi Chemical ( Co., Ltd.], PTMG3000 [polytetramethylene ether glycol with Mn = 3,000, manufactured by Mitsubishi Chemical Co., Ltd.] and Sanniks Diol GP-3000 [polypropylene ether triol with Mn = 3,000, Sanyo Chemical Industries, Ltd. Manufactured] and the like.

  Examples of aromatic polyether polyols include ethylene oxide (hereinafter abbreviated as EO) adducts of bisphenol A [EO 2 mol adduct of bisphenol A, EO 4 mol adduct of bisphenol A, EO 6 mol adduct of bisphenol A, and bisphenol A. EO 8 mol adduct, bisphenol A EO 10 mol adduct and bisphenol A EO 20 mol adduct, etc.] and bisphenol A propylene oxide (hereinafter abbreviated as PO) adduct [bisphenol A PO 2 mol adduct, bisphenol A PO3 molar adducts, PO5 molar adducts of bisphenol A, etc.], and EO or PO adducts of resorcin, and the like.

  Examples of the polyester polyol (a12) include condensed polyester polyols, polylactone polyols, polycarbonate polyols, and castor oil-based polyols.

The condensed polyester polyol is a polyester polyol of a low molecular weight (less than Mn300) polyhydric alcohol and a polyvalent carboxylic acid having 2 to 10 carbon atoms or an ester-forming derivative thereof.
Low molecular weight polyhydric alcohols include dihydric to octahydric or higher aliphatic polyhydric alcohols less than Mn300 and alkylene oxides of dihydric to octavalent or higher phenols less than Mn300 (EO, PO, 1, 2). -, 1,3-, 2,3- or 1,4-butylene oxide and the like, hereinafter abbreviated as AO) and low molar adducts can be used.
Among the low molecular weight polyhydric alcohols that can be used in the condensed polyester polyol, ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 1,6-hexane glycol, bisphenol A EO or PO low mole Adducts and combinations thereof.

  Examples of the polyvalent carboxylic acid having 2 to 10 carbon atoms or ester-forming derivatives thereof that can be used in the condensed polyester polyol include aliphatic dicarboxylic acids (succinic acid, adipic acid, azelaic acid, sebacic acid, fumaric acid, maleic acid, etc.) , Alicyclic dicarboxylic acids (such as dimer acid), aromatic dicarboxylic acids (such as terephthalic acid, isophthalic acid and phthalic acid), trivalent or higher polycarboxylic acids (such as trimellitic acid and pyromellitic acid), these Anhydrides (succinic anhydride, maleic anhydride, phthalic anhydride, trimellitic anhydride, etc.), acid halides thereof (adipic acid dichloride, etc.), low molecular weight alkyl esters thereof (dimethyl succinate, dimethyl phthalate, etc.) These combinations are listed.

  Specific examples of the condensed polyester polyol include polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyhexamethylene isophthalate diol, polyneopentyl adipate diol, polyethylene propylene adipate diol, polyethylene butylene adipate diol, polybutylene Hexamethylene adipate diol, polydiethylene adipate diol, poly (polytetramethylene ether) adipate diol, poly (3-methylpentylene adipate) diol, polyethylene azelate diol, polyethylene sebacate diol, polybutylene azelate diol, polybutylene seba Kate diol and polyneopentyl terephthalate diol It is.

The polylactone polyol is a polyaddition product of a lactone to the low molecular weight polyhydric alcohol. Examples of the lactone include lactones having 4 to 12 carbon atoms (for example, γ-butyrolactone, γ-valerolactone, and ε-caprolactone). It is done.
Specific examples of the polylactone polyol include polycaprolactone diol, polyvalerolactone diol, and polycaprolactone triol.

  Examples of the polycarbonate polyol include the low molecular weight polyhydric alcohol, a low molecular carbonate compound (for example, an alkyl group having 1 to 6 carbon atoms, an alkylene carbonate having an alkylene group having 2 to 6 carbon atoms, and 6 to 9 carbon atoms). And a polycarbonate polyol produced by condensation with a dealcoholization reaction. Two or more low molecular weight polyhydric alcohols and alkylene carbonates may be used in combination.

  Specific examples of the polycarbonate polyol include polyhexamethylene carbonate diol, polypentamethylene carbonate diol, polytetramethylene carbonate diol, and poly (tetramethylene / hexamethylene) carbonate diol (for example, 1,4-butanediol and 1,6-hexane). And a diol obtained by condensing a diol with a dialkyl carbonate while causing a dealcoholization reaction).

  Examples of commercially available polycarbonate polyols include NIPPOLAN 980R [polyhexamethylene carbonate diol with Mn = 2,000, manufactured by Nippon Polyurethane Industry Co., Ltd.] and Duranol G4672 [poly (tetramethylene / hexamethylene) carbonate with Mn = 2,000. Diol, manufactured by Asahi Kasei Chemicals Corporation] and the like.

  The castor oil-based polyol includes castor oil and modified castor oil modified with polyol or AO. Modified castor oil can be produced by transesterification of castor oil and polyol and / or AO addition. Castor oil-based polyols include castor oil, trimethylolpropane-modified castor oil, pentaerythritol-modified castor oil, and EO (4 to 30 mol) adduct of castor oil.

  Mn of the polymer polyol (a1) is usually 300 or more, preferably 300 to 10,000, more preferably 300 to 6,000, from the viewpoint of mechanical properties of the polyurethane resin (U).

  Examples of the low molecular polyol (a2) having a Mn of less than 300 include aliphatic dihydric alcohols, aliphatic trihydric alcohols and tetrahydric or higher aliphatic alcohols. Among (a2), from the viewpoint of water resistance and heat-resistant yellowing, a divalent or trivalent aliphatic alcohol is preferable. Examples of the aliphatic dihydric alcohol include ethylene glycol, propylene glycol, and 1,4-butanediol. Neopentyl glycol and 1,6-hexanediol are particularly preferable, and trimethylolpropane is particularly preferable as the aliphatic trihydric alcohol.

  As the polyisocyanate (b), which is an essential component of the urethane resin (U), those conventionally used for the production of urethane resins can be used. The polyisocyanate (b) is an aromatic polyisocyanate (b1) having 2 to 3 or more isocyanate groups and having 6 to 20 carbon atoms (excluding carbon in the isocyanate group, the same shall apply hereinafter), and 2 to 2 carbon atoms. 18 aliphatic polyisocyanate (b2), alicyclic polyisocyanate (b3) having 4 to 15 carbon atoms, araliphatic polyisocyanate (b4) having 8 to 15 carbon atoms and derivatives of (b1) to (b4) ( For example, isocyanurate product).

  Examples of the aromatic polyisocyanate having 6 to 20 carbon atoms (b1) include 1,3- or 1,4-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate (TDI), 4,4′-. Or 2,4′-diphenylmethane diisocyanate (MDI), 1,5-naphthylene diisocyanate, 4,4 ′, 4 ″ -triphenylmethane triisocyanate, m- or p-isocyanatophenylsulfonyl isocyanate, crude MDI, etc. Can be mentioned.

  Examples of the aliphatic polyisocyanate (b2) having 2 to 18 carbon atoms include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), dodecamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2 -Isocyanatoethyl-2,6-diisocyanatohexanoate and the like.

  Examples of the alicyclic polyisocyanate (b3) having 4 to 15 carbon atoms include isophorone diisocyanate (IPDI), 4,4-dicyclohexylmethane diisocyanate (hydrogenated MDI), cyclohexylene diisocyanate, and methylcyclohexylene diisocyanate (hydrogenated TDI). Bis (2-isocyanatoethyl) -4-cyclohexene-1,2-dicarboxylate, 2,5- or 2,6-norbornane diisocyanate, and the like.

  Examples of the aromatic aliphatic polyisocyanate (b4) having 8 to 15 carbon atoms include m- and / or p-xylylene diisocyanate (XDI), α, α, α ′, α′-tetramethylxylylene diisocyanate (TMXDI). Etc.

  Of the polyisocyanates (b), (b2) and (b3) are preferable from the viewpoint of mechanical properties and weather resistance of the resulting film, (b3) is more preferable, and IPDI and hydrogenated MDI are particularly preferable. is there.

  As the compound (c) containing a carboxyl group and an active hydrogen atom, a compound containing 2 to 10 carbon atoms containing a carboxyl group [dialkylol alkanoic acid (for example, 2,2-dimethylolpropionic acid, 2,2- Dimethylolbutanoic acid, 2,2-dimethylolheptanoic acid and 2,2-dimethyloloctanoic acid), tartaric acid and amino acids (for example, glycine, alanine and valine)] and the like.

  By using the compound (c) containing a carboxyl group and an active hydrogen atom as a constituent component of the urethane resin (U), the carboxyl group in (c) and a crosslinking agent (L) described later undergo a crosslinking reaction, resulting in high A film with high strength and high hardness can be obtained.

  The amount of (c) used can be appropriately selected depending on the type and amount of the crosslinking agent (L) to be used, but is preferably 10 to 50% by weight, more preferably based on the weight of (U). Is 20-30% by weight.

Examples of the compound (d) containing a hydrophilic group and an active hydrogen atom include a compound (d1) containing an anionic group and an active hydrogen atom, and a compound (d2) containing a cationic group and an active hydrogen atom.
Examples of (d1) include a carboxyl group as an anionic group and a compound having 2 to 10 carbon atoms [similar to the above compound (c) containing a carboxyl group and an active hydrogen atom], and an anionic group. Compounds having a sulfonic acid group and having 2 to 16 carbon atoms [3- (2,3-dihydroxypropoxy) -1-propanesulfonic acid and sulfoisophthalic acid di (ethylene glycol) ester, etc.], sulfamine as an anionic group Examples include compounds having an acid group and having 2 to 10 carbon atoms [N, N-bis (2-hydroxylethyl) sulfamic acid and the like] and the like, and salts obtained by neutralizing these compounds with a neutralizing agent.

  As described above, the compound (c) containing a carboxyl group and an active hydrogen atom is essential for introducing a reactive group (carboxyl group) into the urethane resin (U), and has a hydrophilic property to the urethane resin (U). It can also be used to give.

  Among (d1), 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, and salts thereof are preferable from the viewpoint of the resin physical properties of the obtained film and the dispersion stability of the polyurethane resin aqueous dispersion. It is.

Examples of the neutralizing agent used in the salt of (d1) include ammonia, amine compounds having 1 to 20 carbon atoms, and alkali metal hydroxides (such as sodium hydroxide, potassium hydroxide, and lithium hydroxide).
Examples of the amine compound having 1 to 20 carbon atoms include primary amines such as monomethylamine, monoethylamine, monobutylamine and monoethanolamine, secondary amines such as dimethylamine, diethylamine, dibutylamine, diethanolamine, diisopropanolamine and methylpropanolamine. Examples include amines and tertiary amines such as trimethylamine, triethylamine, dimethylethylamine, dimethylmonoethanolamine and triethanolamine.

  As the neutralizing agent used for the salt of (d1), a compound having a high vapor pressure at 25 ° C. is preferable from the viewpoint of the drying property of the resulting polyurethane resin aqueous dispersion and the water resistance of the resulting film. From such a viewpoint, ammonia is most preferable as the neutralizing agent used in the salt of (d1).

  As the compound (d2) containing a cationic group and an active hydrogen atom, for example, a tertiary amino group-containing diol having 1 to 20 carbon atoms [N-alkyl dialkanolamine (for example, N-methyldiethanolamine, N-propyldiethanolamine, N -Butyldiethanolamine and N-methyldipropanolamine) and N, N-dialkylmonoalkanolamine (for example, N, N-dimethylethanolamine) and the like] and the like, and the like.

  The neutralizing agent used in (d1) and (d2) is added before the urethanization reaction, during the urethanization reaction, after the urethanization reaction, before the water dispersion step, during the water dispersion step, or after the water dispersion. However, from the viewpoint of the stability of the urethane resin and the stability of the aqueous dispersion, it is preferably added before or during the aqueous dispersion process.

  The amount of (d) used is such that the content of the hydrophilic group in (U) is preferably 0.01 to 5% by weight, more preferably 0.1 to 5% by weight, based on the weight of (U). It is 4% by weight, particularly preferably 1 to 3% by weight. In addition, when using (c) as (d), the said content is a value remove | excluding the required amount of (c) for providing a reactive group.

The content of the hydrophilic group in the present invention means the weight percent of the unneutralized cationic group or anionic group, and does not include the weight of the counter ion. For example, the content of the hydrophilic group in (d1) is such that, in the case of 2,2-dimethylolpropionic acid triethylamine salt, the weight percentage of the carboxyl group (—COOH) is 3- (2,3-dihydroxypropoxy). In the case of triethylamine salt of -1-propanesulfonic acid, it refers to the weight percent of the sulfo group (—SO ₃ H). Further, the content of the hydrophilic group in (d2) refers to the weight% of only the nitrogen atom in the tertiary amino group.

  Examples of the chain extender (e) include water, diamines having 2 to 10 carbon atoms (for example, ethylene diamine, propylene diamine, hexamethylene diamine, isophorone diamine, toluene diamine and piperazine), and polyalkylene polyamines having 2 to 10 carbon atoms ( For example, diethylenetriamine and triethylenetetramine), hydrazine or derivatives thereof (dibasic acid dihydrazide such as adipic acid dihydrazide) and aminoalcohols having 2 to 10 carbon atoms (such as ethanolamine, diethanolamine, 2-amino-2-methylpropanol and Ethanolamine) and the like.

  As the reaction terminator (f), C1-C8 monoalcohols (methanol, ethanol, isopropanol, cellosolves, carbitols, etc.), C1-C10 monoamines (monomethylamine, monoethylamine, mono Mono- or dialkylamines such as butylamine, dibutylamine and monooctylamine; mono- or dialkanolamines such as monoethanolamine, diethanolamine and diisopropanolamine).

Since the amount of (e) and (f) used affects the Mn, terminal amino group content and urea group content of (U), it is necessary to use them in a range that does not impair the effects of the present invention. Specifically, it is necessary that Mn of (U) has a value described later, and when an amine compound is used, the content of the terminal amino group of (U) should be within a value described later. . Moreover, it is preferable to use the quantity from which the urea group content in (U) becomes a below-mentioned value.
Urethane resins may be used alone or in combination of two or more.

  In the urethane resin aqueous dispersion in the invention, (U) may be dispersed in water in the presence of the dispersant (h) from the viewpoint of the dispersibility of (U) and the stability of the aqueous dispersion.

  As the dispersant (h), nonionic surfactant (h1), anionic surfactant (h2), cationic surfactant (h3), amphoteric surfactant (h4) and other emulsifying dispersant (h5) ). (H) may be used alone or in combination of two or more.

The content of (h) is usually 0.01 to 20% by weight, preferably 0.1 to 10% by weight, and more preferably 1 to 5% by weight based on the weight of the urethane resin (U).
When (U) is a urethane resin having a hydrophilic group, the total content of (d) and (h) based on the weight of (U) is usually 0.3 to 20% by weight. , Preferably 0.6 to 10% by weight, more preferably 1 to 5% by weight.

  The urethane resin (U) in the present invention can contain additives such as antioxidants, anti-coloring agents, weathering stabilizers, plasticizers, and mold release agents as necessary. The amount of these additives used is usually 10% by weight or less, more preferably 3% by weight or less, and particularly preferably 1% by weight or less based on the weight of (U).

  In the present invention, the urethane group content in the urethane resin (U) is preferably based on the weight of (U) from the viewpoint of the mechanical properties, durability, chemical resistance, and abrasion resistance of the resulting film. Is 0.5 to 5.0 mmol / g, more preferably 0.8 to 4.2 mmol / g, and particularly preferably 1.1 to 3.4 mmol / g.

  Polyol (a), polyisocyanate (b), compound (c) containing carboxyl group and active hydrogen atom, compound (d) containing hydrophilic group and active hydrogen atom if necessary, chain extender (e) And the urethane group content of a urethane resin (U) can be made into a desired range by adjusting the quantity of a reaction terminator (f) suitably.

The urethane group content and urea group content of the polyurethane resin (U) are the N atom content determined by a nitrogen analyzer [ANTEK7000 (manufactured by Antec)], the ratio of urethane groups and urea groups determined by ¹ H-NMR, and It calculates from the below-mentioned allohanate group and burette group content. ^{The 1} H-NMR measurement is carried out by the method described in “Structural study of polyurethane resin by NMR: Takeda Laboratory Report 34 (2), 224-323 (1975)”. That is, when ¹ H-NMR is measured and an aliphatic group is used, the urea group is determined from the ratio of the integral amount of hydrogen derived from a urea group near a chemical shift of 6 ppm and the integral amount of hydrogen derived from a urethane group near a chemical shift of 7 ppm. The weight ratio of the urethane groups is measured, and the urethane group and urea group contents are calculated from the weight ratio, the N atom content, the allohanate group, and the burette group content. When aromatic isocyanate is used, the weight ratio of urea group and urethane group is calculated from the ratio of the integral amount of hydrogen derived from urea groups near the chemical shift of 8 ppm and the integral amount of hydrogen derived from urethane groups near the chemical shift of 9 ppm, The urea group content is calculated from the weight ratio and the N atom content.

In general, the molecular terminal of the polyurethane resin is a hydroxyl group derived from a hydroxyl group of a raw material, or an amino group derived from a reaction of an isocyanate group with water or an amino group of a raw material. In the step of dispersing the polyurethane resin (U) in water, the terminal amino group is generated by hydrolysis of the urethane group, urea group, allophanate group or burette group. Since this terminal amino group has poor water resistance compared to the terminal hydroxyl group, a polyurethane resin having a high content of terminal amino groups tends to have poor water resistance.
Therefore, in the present invention, the terminal amino group content in the urethane resin (U) is preferably 0 to 0.35 mmol / g, more preferably 0 to 0.00, based on the weight of (U), from the viewpoint of water resistance. 2 mmol / g, particularly preferably 0 to 0.15 mmol / g, most preferably 0 to 0.1 mmol / g.

  Polyol (a), polyisocyanate (b), compound (c) containing carboxyl group and active hydrogen atom, compound (d) containing hydrophilic group and active hydrogen atom if necessary, chain extender (e) And the terminal amino group content of a urethane resin (U) can be made into a desired range by adjusting the quantity of reaction stopper (f) suitably.

The terminal amino group content of the urethane resin (U) is obtained by calculating the total amino value and tertiary amine value of the polyurethane resin by the following method, and calculating the terminal amino group content (mmol / g) by the following formula.
Terminal amino group content (mmol / g) = (total amine value−tertiary amine value) /56.1
(1) Total amine value After dissolving the polyurethane resin in 50 ml of toluene in a 100 ml flask, add 20 ml of acetic anhydride and titrate 0.5 mol / l hydrochloric acid / methyl alcohol using xylene cyanol FF / methyl orange mixed indicator. Titration is carried out with the solution (the end point is the point where the color of the indicator has changed from green to reddish brown).
Total amine number = a × f / (S × 28.05)
a: The number of titration ml of 0.5 mol / l hydrochloric acid / methyl alcohol titration solution.
f: The titer of 0.5 mol / l hydrochloric acid / methyl alcohol titration solution.
S: Amount of polyurethane resin collected (g)
(2) Tertiary amine value After dissolving the urethane resin in 50 ml of toluene in a 100 ml flask, add 20 ml of acetic anhydride, shake well, and leave at room temperature for 30 minutes. Titrate with 0.5 mol / l hydrochloric acid / methyl alcohol titration solution using xylene cyanol FF / methyl orange mixed indicator (the end point is the point where the indicator color changed from green to reddish brown) and read the titration ml number The tertiary amine value is calculated by the following formula.
Tertiary amine value = a × f / (S × 28.05)
a: titration ml number of 0.5 mol / l hydrochloric acid / methyl alcohol titration solution f: titer of 0.5 mol / l hydrochloric acid / methyl alcohol titration solution S: amount of urethane resin collected (g)

  In the present invention, the urea group content in the urethane resin (U) is preferably 2.0 mmol / g or less based on the weight of (U) from the viewpoint of film forming property and water resistance of the resulting film. More preferably, it is 0.2 mmol / g or less, particularly preferably 0.1 mmol / g or less, particularly preferably 0.05 mmol / g or less, and most preferably 0.02 mmol / g or less.

  In order to bring the urea group content in the urethane resin (U) into a desired range, the amino group content, water content and isocyanate group content in the raw material of (U) may be appropriately adjusted.

  In the present invention, the total content of allophanate groups and burette groups in the urethane resin (U) is 0.1 mmol based on the weight of (U) from the viewpoint of film forming properties and water resistance of the resulting film. / G or less, more preferably 0.03 mmol / g or less, particularly preferably 0.01 mmol / g or less, particularly preferably 0.003 mmol / g or less, and most preferably 0.001 mmol / g or less. .

  In order to set the total content of allophanate groups and burette groups of the urethane resin (U) to a desired range, the content of amino groups in the raw material of (U), the equivalents of isocyanate groups to the equivalents of hydroxyl groups and amino groups The ratio, the urethanization reaction temperature and the like may be adjusted as appropriate. Especially about reaction temperature, the production | generation of an allophanate group and a burette group can be suppressed by setting it as 120 degrees C or less or 180 degrees C or more.

The total content of allophanate groups and burette groups of the urethane resin (U) is calculated by a gas chromatograph [Shimadzu GC-9A (manufactured by Shimadzu Corporation)]. A 50 g DMF solution containing 0.01% by weight di-n-butylamine and 0.01% by weight naphthalene (internal standard) was prepared, and the sample was weighed into a test tube with a stopper. 2 g is added and the test tube is heated in a constant temperature water bath at 90 ° C. for 2 hours. After cooling to room temperature, 10 μl of acetic anhydride is added and stirred for 10 minutes. Further, 50 μl of di-n-propylamine is added and shaken for 10 minutes, and then gas chromatographic measurement is performed. In parallel, blank measurement is performed, the amine consumption is determined from the difference from the test value, and the total content of allophanate groups and burette groups is measured.
[Gas chromatographic conditions]
Apparatus: Shimadzu GC-9A
Column: 10% PEG-20M on Chromosorb WAW DMLS 60/80 mesh glass column 3 mmφ × 2 m
Column temperature: 160 ° C., sample introduction part temperature: 200 ° C., carrier gas: nitrogen 40 ml / min detector: FID, sample injection amount: 2 μl
[Calculation formula for the total content of allophanate groups and burette groups]
Total content of allophanate group and burette group = {(BA) / B} × 0.00155 / S
A: (Di-n-butylacetamide peak area / naphthalene peak area) of sample
B: blank (peak area of di-n-butylacetamide / peak area of naphthalene)
S: Amount of urethane resin collected (g)

  In the present invention, the content of the terminal isocyanate group before the dispersion of the urethane resin (U) in water is preferably 0.2 mmol / g or less, more preferably 0.15 mmol / g or less, particularly based on the weight of (U). Preferably it is 0.1 mmol / g or less, Most preferably, it is 0.05 mmol / g or less. If it is this range, since the urea group content and terminal amino group content of (U) after dispersion in water can be targeted, the effects of the present invention can be sufficiently exerted.

  The content of the terminal isocyanate group of (U) before dispersion in water is mainly the ratio of the number of equivalents of isocyanate groups in the raw material of (U) to the total number of equivalents of hydroxyl groups, amino groups and water, and the reaction rate of the urethanization reaction. It is possible to control by.

  In the present invention, the Mn of the urethane resin (U) is preferably 10,000 to 1,000,000, more preferably from the viewpoints of mechanical properties, durability, chemical resistance, wear resistance, and the like of the resulting film. Is 10,000 to 500,000, particularly preferably 10,000 to 200,000, and most preferably 10,000 to 100,000.

  Polyol (a), polyisocyanate (b), compound (c) containing carboxyl group and active hydrogen atom, compound (d) containing hydrophilic group and active hydrogen atom if necessary, chain extender (e) And Mn of urethane resin (U) can be made into a desired range by adjusting the quantity of reaction terminator (f) suitably.

  In the present invention, the weight average molecular weight (hereinafter abbreviated as Mw) of the urethane resin (U) and the ratio of Mn (Mw / Mn) are preferably 1.5 to 3.5, more preferably from the viewpoint of film forming properties. Is 1.75 to 3.25, particularly preferably 2.0 to 3.0.

  The Mw / Mn of the urethane resin (U) can be set within a predetermined range by appropriately adjusting the conditions (for example, stirring and mixing) relating to the uniformity of the urethane reaction of (U).

  Mn and Mw of the urethane resin (U) are measured by gel permeation chromatography (GPC). Urethane resin (U) was added to DMF so that the solid content of the polyurethane resin was 0.0125% by weight, stirred and dissolved at room temperature for 1 hour, and then filtered through a filter having a pore size of 0.3 μm. The Mw and Mn of the urethane resin contained in is measured by using DMF as a solvent and polystyrene as a molecular weight standard.

  In the present invention, the volume average particle diameter (Dv) of the urethane resin (U) is preferably 0.01 to 1 μm, more preferably 0.02 to 0, from the viewpoint of dispersion stability of the urethane resin aqueous dispersion. 0.7 μm, particularly preferably 0.03 to 0.4 μm.

  The volume average particle diameter (Dv) of the urethane resin (U) is determined by the hydrophilic group in the urethane resin (U), the amount of the dispersant, the type of the disperser used in the dispersion step, and the operating conditions. Therefore, in order to bring the volume average particle diameter (Dv) of (U) into a desired range, in the dispersion step, an apparatus selected from a rotary disperser, an ultrasonic disperser and a kneader described later is used. The content of the hydrophilic group in (U) and the content of the dispersant (h) may be appropriately adjusted.

  The volume average particle size (Dv) is obtained by diluting an aqueous dispersion of urethane resin (U) with ion-exchanged water so that the solid content of the polyurethane resin becomes 0.01% by weight, and then measuring the light scattering particle size distribution analyzer [ELS- 8000 {manufactured by Otsuka Electronics Co., Ltd.}].

The elongation at break of the urethane resin (U) is preferably 200% or more, more preferably 200 to 1000%, particularly preferably 300 to 500 under the temperature condition of 25 ° C. from the viewpoint of followability to the substrate. %.
The elongation at break of the urethane resin (U) was determined by pouring the aqueous dispersion of the urethane resin (U) into a mold so that the film thickness after drying was 200 μm, and drying the film at 105 ° C. for 3 hours. After cutting out with dumbbell shape No. 3 according to 6251, it can be measured under the condition of a pulling speed of 500 mm / min using Shimadzu Autograph AGS-500B.

  Polyol (a), polyisocyanate (b), compound (c) containing carboxyl group and active hydrogen atom, compound (d) containing hydrophilic group and active hydrogen atom if necessary, chain extender (e) And the elongation at break of urethane resin (U) can be made into a desired range by adjusting suitably the kind and quantity of reaction terminator (f).

  In the present invention, the urethane resin (U) contains a polyol (a), a polyisocyanate (b), a compound (c) containing a carboxyl group and an active hydrogen atom, and a hydrophilic group and an active hydrogen atom used as necessary. It can be obtained by reacting compound (d), chain extender (e) and reaction terminator (f) by heating in a heatable facility. For example, the raw material (U) is charged in a container and uniformly stirred, and then heated without stirring in a heating dryer or heating furnace, a simple pressure reactor (autoclave), Kolben, uniaxial or biaxial kneading. And a method of reacting by heating with stirring or kneading in a machine, a plast mill or a universal kneader. Among them, the method of heating and reacting while stirring or kneading increases the homogeneity of the obtained urethane resin (U), and the mechanical properties, durability, chemical resistance and abrasion resistance of the resulting film, etc. Is preferred because it tends to be more excellent. Among the methods of heating and reacting while stirring or kneading, a uniaxial or biaxial kneader excellent in stirring strength and heating ability is preferable. Examples of the uniaxial or biaxial kneader include a continuous kneader (manufactured by Kurimoto Seiko Co., Ltd.), a uniaxial kneader, and a biaxial extruder.

  100-250 degreeC is preferable, as for the reaction temperature at the time of manufacturing a urethane resin (U), More preferably, it is 100-120 degreeC or 180-240 degreeC, Most preferably, it is 190-230 degreeC. The time for producing (U) can be appropriately selected depending on the equipment used, but generally 1 minute to 100 hours is preferable, more preferably 3 minutes to 30 hours, and particularly preferably. 5 minutes to 10 hours. If it is this range, (U) which can fully exhibit the effect of the present invention will be obtained.

  In order to control the urethanization reaction rate, known reaction catalysts (such as tin octylate and bismuth octylate) and reaction retarders (such as phosphoric acid) can be used. The addition amount of these catalysts or reaction retarders is preferably 0.001 to 3% by weight, more preferably 0.005 to 2% by weight, and particularly preferably 0.01 to 1% by weight based on the weight of (U). %.

  The urethane resin aqueous dispersion for decorative film of the present invention can be obtained by adding a crosslinking agent (L) to the aqueous dispersion of the urethane resin (U).

  The aqueous dispersion of urethane resin (U) can be produced by neutralizing the above urethane resin (U) with a neutralizing agent or by dispersing in water while neutralizing. Specifically, for example, a method of dispersing in water at a temperature lower than the melting temperature of the urethane resin (U) using a rotary dispersion mixing device as the dispersion mixing device can be mentioned.

  When the above method is used, the urethane resin (U) has a melting temperature of 70 to 280 ° C., and is usually solid at room temperature, preferably 0.2 to 50 mm at 25 ° C., more preferably 0.5. A particulate matter having a volume average particle diameter of ˜30 mm, particularly preferably 1 to 10 mm is preferable from the viewpoint of easy supply to a rotary dispersion mixing apparatus.

  As means for adjusting the urethane resin (U) into particles, means such as cutting, pelletizing, granulating or pulverizing can be used. This adjustment to the particulate form can be carried out in water or in the absence of water. For example, the method of making the urethane resin (U) rolled into the sheet form into a particulate form with a square pellet machine [made by Horai Co., Ltd.] can be mentioned.

  The urethane resin (U) adjusted to particles is introduced into a rotary dispersion mixing device together with water. The main dispersion principle of this device is to pulverize the particles by applying a shearing force to the particles from the outside by rotation of the drive unit. This is the principle of dispersion. The apparatus can be operated at normal pressure or under pressure.

  Examples of the rotary dispersion mixing apparatus include TK homomixer [manufactured by Primics Co., Ltd.], Claremix [manufactured by Mtechnics Co., Ltd.], Philmix [manufactured by Primix Co., Ltd.], Ultra Turrax [manufactured by IKA Corporation] ], Ebara Milder [manufactured by Ebara Manufacturing Co., Ltd.], Cavitron (manufactured by Eurotech) and biomixer [manufactured by Nippon Seiki Co., Ltd.], and these two or more types of apparatuses may be used in combination. .

  The temperature of the dispersion when the urethane resin (U) is dispersed and mixed using a rotary dispersion mixing apparatus is selected from the viewpoint of preventing decomposition and deterioration of the urethane resin (U) as a dispersion. ), Lower than the melting temperature, preferably 5 ° C. or more lower than the melting temperature, more preferably room temperature or higher, more preferably 10 to 120 ° C. lower than the melting temperature, and room temperature or higher. From the viewpoint of

  The residence time in the rotary dispersion mixing apparatus of the urethane resin (U) and water is usually 0.1 to 60 minutes, preferably 10 to 30 minutes from the viewpoint of decomposition and deterioration suppression.

  In the method for producing an aqueous dispersion of the urethane resin (U), it is not necessary to neutralize the terminal isocyanate prepolymer as in the conventional prepolymer mixing method, so that ammonia, primary amine or secondary amine is added in the middle. Even if it is used as a compatibilizer, an aqueous dispersion in which a high molecular weight polyurethane resin (U) is dispersed can be obtained.

  Examples of the crosslinking agent (L) in the present invention include an aqueous oxazoline-based crosslinking agent (water-soluble oxazoline group-containing resin and aqueous oxazoline group-containing emulsion), an aqueous (poly) carbodiimide-based crosslinking agent (water-soluble carbodiimide group-containing resin, and aqueous carbodiimide). Group-containing emulsions) and water-based epoxy resin-based crosslinking agents (water-soluble epoxy group-containing resins, water-based epoxy group-containing emulsions, etc.) and the like. Among these, from the viewpoint of storage stability and reactivity, an aqueous (poly) carbodiimide crosslinking agent is preferable, and an aliphatic carbodiimide crosslinking agent having an imide equivalent of 100 to 700 is more preferable.

  Commercially available products of the crosslinking agent (L) include, for example, Carbodilite E-02 [manufactured by Nisshinbo Co., Ltd.] as an aqueous (poly) carbodiimide crosslinking agent, and Denacol EX-411 [Nagase ChemteX Corporation as an aqueous epoxy resin crosslinking agent]. ) Made] etc.

  From the viewpoint of physical properties of the cured film, the weight ratio [(U) :( L)] of the urethane resin (U) and the crosslinking agent (L) is preferably 50:50 to 99: 1, and more preferably 60: 40-90: 10.

The decorative film of the present invention is formed by applying at least the urethane resin aqueous dispersion for a decorative film of the present invention on the guard film (G) and then drying to form a clear layer (F). ) Is obtained.
The drying conditions for forming the clear layer (F) are not particularly limited as long as the reaction between the urethane resin (U) and the crosslinking agent (L) in the clear layer (F) can be suppressed. Is preferably 1 to 30 minutes under a temperature condition of 25 to 100 ° C, more preferably 3 to 15 minutes under a temperature condition of 60 to 100 ° C.

  The clear layer (F) is a decorative molded body in which the base material is decorated with a decorative film. The hardness, non-adhesiveness, solvent resistance, chemical resistance, weather resistance, scratch resistance, impact resistance and water resistance In addition to imparting physical and chemical properties such as properties, transparency, glossiness and smoothness are exhibited.

  The elongation at break of the clear layer (F) is preferably 200% or more, more preferably 200 to 1000%, particularly preferably 300 to 500, at a temperature of 25 ° C. from the viewpoint of followability to the substrate. %.

  The thickness of the clear layer (F) is preferably 5 to 100 μm, more preferably 10 to 80 μm from the viewpoint of strength.

  Examples of the method of applying the urethane resin aqueous dispersion for decorative film to the guard film (G) include an applicator, a bar coater, and a die coater, and coating using this applicator is particularly preferable.

  When decorating the base material with the decorative film of the present invention, the decorative film is set on the base material and adhered to the base material by vacuum molding or the like, and then heat-treated to obtain urethane in the clear layer (F). The resin (U) and the crosslinking agent (L) are reacted to obtain a decorated molded product. The guard film (G) may be peeled off before the heat treatment or may be peeled off after the heat treatment. As said heat processing conditions, 0.5 to 60 minutes are preferable under the temperature conditions of 100-180 degreeC, More preferably, it is 1 to 40 minutes under the temperature conditions of 100-140 degreeC.

  The guard film (G) in the present invention is a support for supporting the clear layer (F), the adhesive layer (A) and the like, and is used for maintaining good workability when decorating the base material. .

  The material and form of the guard film (G) are not particularly limited. For example, Lumirror S-10 [manufactured by Toray Industries, Inc.], Novaclear (registered trademark) SG007 [trade name, manufactured by Mitsubishi Chemical Corporation], Diacral (registered) (Trademark) series [Mitsubishi Resin Co., Ltd.] polyethylene terephthalate (PET) film and the like.

  The contact angle of the guard film (G) with respect to water is preferably 60 ° or more. When the contact angle is less than 60 °, the film composed of the clear layer (F) and the adhesive layer (A) is difficult to peel.

  Examples of the adhesive layer (A) in the present invention include acrylic resin polymers, polyurethane polymers, gun fluorine polymers, polycarbonate, PVC polymers, films such as ABS, PET, and PBT.

  In the decorative film of the present invention, sufficient hardness can be obtained only by a coating film obtained by drying the decorative urethane resin aqueous dispersion of the present invention, but if necessary, by blending a filler or the like. Furthermore, the hardness can be improved. Examples of the filler include colloidal silica [Snowtex C and Snowtex 20: manufactured by Nissan Chemical Industries, Ltd.].

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these. Hereinafter, the part means part by weight.
Example 1
[Production of Aqueous Urethane Resin Dispersion (E-1)]
56.03 parts of 1,4-cyclohexanedimethanol, DURANOL G4672 [poly (tetramethylene / hexamethylene) carbonate diol of Mn = 2,000, manufactured by Asahi Kasei Chemicals Corporation] 645.69 parts, ethylene glycol 43.45 parts , 100.37 parts of dimethylolpropionic acid, 552.09 parts of 4,4-dicyclohexylmethane diisocyanate, 2.10 parts of IRUGANOX245 [manufactured by Ciba Japan Co., Ltd.] and Neostan U-100 [Nitto Kasei Co., Ltd.] 0.28 After mixing the parts, it was charged in a KRC kneader that is a twin-screw kneader in a nitrogen atmosphere and kneaded at 210 ° C for 15 minutes to carry out a urethanization reaction. A polyurethane resin (U-1) was obtained by cutting with a square pelletizer. Subsequently, 180.04 parts of urethane resin (U-1), 305.34 parts of ion-exchanged water, 59.95 parts of N-methylpyrrolidone and 54.67 parts of 3% aqueous ammonia solution were charged into a pressure-controllable container capable of controlling the temperature. A urethane resin aqueous dispersion (E-1) was obtained by performing a dispersion treatment under stirring at 12,000 rpm using a TK homomixer [manufactured by PRIMIX Co., Ltd.]. (E-1) By adding Carbodilite E-02 [Nisshinbo Co., Ltd .: Imide equivalent 445] 14.01 parts and Snowtex 20 [Nissan Chemical Industry Co., Ltd.] 17.10 parts to 100 parts. An aqueous urethane resin dispersion (E-1) of the present invention was obtained.
The terminal amino group content in the urethane resin (U-1) is 0.01 mmol / g, the Mn of (U-1) is 20,000, the ratio of Mw to Mn (Mw / Mn) is 2.46, and the urethane resin aqueous solution In the dispersion (E-1), the volume average particle diameter (Dv) of (U-1) was 0.100 μm, and the elongation at break of (U-1) was 300%.

[Preparation of decorative film]
The urethane resin aqueous dispersion (E-1) was applied onto Lumirror S-10 (manufactured by Toray Industries, Inc.) as a guard film with an applicator so that the film thickness after drying was 40 μm, and the coating was made at 80 ° C. for 10 minutes. A clear layer is formed by drying, and further an adhesive [Byron UR-3200: manufactured by Toyobo Co., Ltd.] is applied on the clear layer using a bar coater so that the film thickness becomes 20 μm. It dried for minutes and formed the contact bonding layer and obtained the decorating film of this invention.

Comparative Example 1
[Production of UV curable resin (H-1) for decorative film]
NK ester BPE-500 [manufactured by Shin-Nakamura Chemical Co., Ltd.] 93 parts, DAROCUR TPO as a radical initiator [manufactured by Ciba Japan Co., Ltd.] 5 parts, and diethylthioxanthone as a sensitizer [manufactured by Nippon Kayaku Co., Ltd.] Two parts of “Kayacure DETX-S”] were kneaded at 25 ° C. for 3 hours using a ball mill to obtain an ultraviolet curable resin (H-1) for a decorative film.

  A clear layer is formed by applying (H-1) onto Lumirror S-10 [manufactured by Toray Industries, Inc.] with an applicator so that the film thickness becomes 40 μm, and further using a bar coater on the clear layer, An adhesive [Byron UR-3200: manufactured by Toyobo Co., Ltd.] was applied so that the thickness was 20 μm, dried at 80 ° C. for 10 minutes to form an adhesive layer, and a decorative film for comparison was obtained.

[Evaluation of decorative film]
Table 1 shows the results of measuring the pencil hardness of the film decorated on the base material by the following method using the decorative film obtained in Example 1 and Comparative Example 1.

<Pencil hardness of the film decorated on the substrate>
A galvanized steel sheet having a length of 50 mm, a width of 100 mm, and a thickness of 0.5 mm is bent at 90 ° along the center line in the vertical direction, and then the decorative film of Example 1 is in contact with the steel sheet on the surface on the mountain side. So that it was in close contact. Then, after peeling off the guard film, set it in a dryer so that one of the two surfaces on the mountain side that intersect perpendicularly is horizontal and the other surface is below the horizontal surface. Heat-treated for 30 minutes. It cooled to room temperature and measured the pencil hardness in each surface of the horizontal direction of a test piece, and a 90 degree bending direction with the following method.
When the decorative film of Comparative Example 1 is used, after the decorative film is brought into close contact with the steel plate in the same manner as described above, one of the two surfaces on the mountain side that intersects vertically becomes horizontal, and the other surface is Set on a belt conveyor type UV irradiation device (eye graphics "ECS-151U") so that it is below the horizontal plane, UV irradiation (exposure amount: 2000 mJ / cm ² as 365 nm) is performed, and the guard film is peeled off After that, the pencil hardness on each surface of the test piece in the horizontal direction and the 90 ° bending direction was measured by the following method.
<Measuring method of pencil hardness>
For the pencil hardness, a coating film scratch tester with a pencil (Mitsubishi Uni) set was used to scratch a coating film under a load of 750 g, and the maximum value of pencil hardness at which the coating film was not damaged was taken as the measured value.

  It can be seen from Table 1 that a film using the urethane resin aqueous dispersion for a decorative film of the present invention provides a decorated molded product having a uniform hardness regardless of the shape of the substrate.

  The decorative film using the urethane resin aqueous dispersion for a decorative film of the present invention can be uniformly extended following the shape and decorated with a uniform film thickness, such as a bumper, a front under spoiler, It can be widely used for automobile parts such as rear under spoiler, side under skirt, side garnish and door mirror, mobile phones, audio products, refrigerators, lighting fixtures, etc., and is particularly suitable as a decorative film for automobile parts.

Claims (6)

  An aqueous urethane resin dispersion for decorative films containing a urethane resin (U) and a crosslinking agent (L). The urethane resin aqueous dispersion for a decorative film according to claim 1, wherein the urethane resin (U) satisfies the following (1) to (5).
(1) The terminal amino group content in (U) is 0 to 0.35 mmol / g based on the weight of (U).
(2) The number average molecular weight (Mn) of (U) is 10,000 to 1,000,000.
(3) The ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of (U) is 1.5 to 3.5.
(4) The volume average particle diameter (Dv) of (U) is 0.01 to 1 μm.
(5) The elongation at break of (U) is 200% or more.   The urethane resin aqueous dispersion for a decorative film according to claim 1 or 2, wherein the polyurethane resin (U) has a carboxyl group neutralized with ammonia.   The weight ratio [(U) :( L)] of the urethane resin (U) and the crosslinking agent (L) is 50:50 to 99: 1. Urethane resin aqueous dispersion.   The urethane resin aqueous dispersion for a decorative film according to any one of claims 1 to 4, wherein the crosslinking agent (L) is an aliphatic carbodiimide having an imide equivalent of 100 to 700.   On a guard film (G), it has a clear layer (F) and an adhesive layer (A) obtained by drying the urethane resin aqueous dispersion for decorative film according to any one of claims 1 to 5. Decorative film.