JPS6342677B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to adhesive compositions. More specifically, the present invention relates to an adhesive composition for producing metallic glossy coatings by a transfer method. Conventionally, methods of laminating metal foil, vacuum deposition, and printing or coating with ink or paint containing metal powder have been known as methods of imparting metallic luster to base materials such as paper, paperboard, and film. There is. Of these, the most common method is to laminate aluminum foil with a thickness of about 7 to 9 μm, but in this case, the purpose of the aluminum foil is only to give it a metallic luster, so it is more economical to make it as thin as possible. However, even if aluminum foil can be made thinner, it can only be about 7 microns thick, and with the price of aluminum foil soaring, this method is greatly affected by the rising price of aluminum foil. Compared to the method of laminating aluminum foil, the vacuum evaporation method produces a thinner evaporated film of about 0.05 μm.
Less susceptible to increases in aluminum prices. However, the metallic luster is easily affected by the surface of the substrate on which the vapor deposition is performed; excellent metallic luster can be obtained when deposited on a smooth surface such as plastic film, but when deposited on an uneven surface such as paper or paperboard, Metal-like luster cannot be obtained. Therefore, it is necessary to perform a smoothing treatment such as lacquer coating in advance, but even then, the metallic luster that is obtained by vapor deposition on the film surface cannot be obtained. Furthermore, in the method of printing or coating with ink or paint containing metal powder, since there is an adhesive composition that binds the metal powder, the metallic luster cannot be obtained as much as the first two methods. Among these, in the vacuum deposition method, when depositing on a substrate with poor smoothness, the present invention does not deposit directly on the substrate, but uses an adhesive to smooth the deposited film on a smooth surface such as a plastic film. The present invention relates to an adhesive composition for producing a metallic luster coating by a transfer method, which can be transferred to a substrate with poor properties and provide an excellent metallic luster similar to that obtained by vapor deposition on a film surface. In this method, an adhesive is applied to the vapor-deposited surface of a plastic film as a transfer material or to the substrate to be transferred, and after drying, the two are bonded together using a pressure roller. The bonded structure is cured under predetermined conditions, and when the adhesive is sufficiently cured, the base material and the plastic film are peeled off. The deposited film is released from the film and transferred to the substrate, resulting in a deposited coating with excellent metallic luster. On the other hand, the film that has been separated from the deposited film can be deposited again and reused. Adhesives used in such applications naturally bond the vapor deposited film and the base material firmly, but at the same time, after curing, they also bond the transfer material, the film, and the base material to which the vapor deposited film has been transferred. It is required that it can be peeled off. The vapor deposited film is usually extremely thin (100 to 1000 Å), so it has many pinholes, and when applying adhesives such as adhesives for dry lamination, the adhesive passes through the vapor deposition film and connects to the transfer material film and the vapor deposition film. It may become impossible to peel off the adhesive, and the hardness of the cured adhesive may not be sufficient, making the deposited film easily damaged. Therefore, in Japanese Patent Publication No. 48-29976, a coating layer that is easily peeled off from the film is provided on the transfer material in advance, and then an adhesive is applied by vapor deposition to prevent the adhesive from coming into direct contact with the film. After curing, peeling is performed. Furthermore, as described above, a method is known in which the transfer material is vapor-deposited without providing a release layer, varnish is applied thereon, the material is bonded to the base material, and the transfer material is peeled off after curing. With varnish, it was impossible to peel it off, and even if it could be peeled off, the deposited film remained on the transfer material in the form of pinholes, and metallic luster could not be obtained. The present inventors have found that the deposited film can be easily peeled off without providing a release layer, and the deposited film and the base material are firmly adhered after transfer, and the deposited film has excellent hardness and tensile strength, and has excellent heat resistance. As a result of intensive studies to obtain an adhesive composition that also has solvent resistance, the present invention was arrived at. That is, the present invention uses a polyether polyol (a) having an average molecular weight of 200 to 2000 and an organic diisocyanate.
Hydroxyl group-terminated urethane prepolymer (A) obtained by reacting (b) with OH/NCO equivalent ratio in the range of 1.3 to 2.0
This is a two-component adhesive composition for producing metallic glossy coatings by a transfer method, comprising: and an organic polyisocyanate (B). In the hydroxyl-terminated urethane prepolymer (A) that is the composition of the present invention, a mixture of polyether diol and polyether triol is used as (a), and the polyether diol includes polyethylene glycol, polypropylene glycol, polybutylene glycol. As polyether triols, polyethylene oxide, polypropylene oxide, etc. are added to glycerin, trimethylolpropane, hexanetriol, etc., and used as polyether triols. The average molecular weight of polyether polyol is 200~
It is 2000. If the average molecular weight is less than 200, the hydroxyl-terminated urethane prepolymer obtained by reacting it with an aromatic diisocyanate will not have sufficient adhesive strength when used as an adhesive, and will not be successfully laminated with a vapor-deposited film. Also, the average molecular weight
If it exceeds 2,000, when the hydroxyl group-terminated urethane prepolymer is transferred to a porous substrate such as paper, it will penetrate into the substrate to a large extent and the deposited film will not be transferred successfully. In addition, the hardness after curing is low, and the surface of the deposited film after transfer is easily scratched, resulting in poor commercial value. From the viewpoint of performance as an adhesive, such as a balance between hardness and flexibility, it is preferable to use polyether diol and polyether triol in combination. When using a mixture of polyether diols and polyether triols, the average functionality is usually between 2.4 and 2.4.
2.9, preferably 2.6 to 2.8. Polyether polyols with different molecular weights, for example, diols with a molecular weight of 200 to 1000 and triols with a molecular weight of 200 to 2000, can also be used together. When producing the prepolymer, in addition to the polyether polyol with a molecular weight of 200 to 2000, other polyols such as polyols with a molecular weight of less than 200 (ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, hexamethylene) are used as necessary. A small amount of glycol, glycerin, trimethylolpropane, etc.) can also be used in combination. The average hydroxyl value of the polyol (polyether polyol having a molecular weight of 200 to 2000 and a mixture with other polypolyols if necessary) used for producing the hydroxyl group-terminated urethane prepolymer is usually 170 to 700, preferably 280 to 670. Examples of the aromatic diisocyanate (b) used as the other component of (A) include tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and xylylene diisocyanate. In the reaction of the above polyether polyol (a) and aromatic diisocyanate (b), the OH/NCO
The equivalent ratio is 1.3 to 2.0, preferably 1.5 to 2.0. If the OH/NCO equivalent ratio is less than 1.3, the viscosity during application of the adhesive may become too high, and there is a risk of gelation when polyether triol is used in combination. If the OH/NCO equivalent ratio exceeds 2.0, a portion of the polyol will remain unreacted. The above reaction can be carried out in the presence or absence of a solvent inert to isocyanate groups. The above solvents include ester solvents (ethyl acetate, butyl acetate, etc.), aromatic hydrocarbon solvents (toluene, etc.), ether solvents (dioxane, tetrahydrofuran, etc.), ketone solvents (cyclohexanone, methyl ethyl ketone, etc.), and mixtures thereof. can give. Examples of the reaction method include a method in which the polyether polyol and the aromatic diisocyanate are charged into a reaction vessel all at once and reacted, and a method in which the polyether polyol or the aromatic diisocyanate is divided into portions and a multistage reaction is performed. The reaction temperature is usually 20-80℃, preferably 60-75℃
It is ℃. Catalysts used in ordinary urethane reactions to accelerate the reaction, such as tin-based catalysts (trimethyltin laurate, trimethyltin hydroxide, dimethyltin dilaurate,
dibutyltin dilaurate, stannath octoate, etc.), lead-based catalysts (red oleate, red 2-
(ethylene hexoate, etc.), cobalt naphthenate, etc. may also be used. The hydroxyl value of the hydroxyl group-terminated urethane prepolymer (A) is usually 50 to 200, preferably 90 to 150. If the hydroxyl value is less than 50, the hardness of the cured adhesive layer will be low, and if it exceeds 200, the flexibility will be lost. The organic polyisocyanate (B), which is the other component of the composition of the present invention, is an NCO-terminated urethane prepolymer of an aromatic diisocyanate, a polymer thereof, a polyol, and an aromatic diisocyanate as described in the section (b). can be given. Examples of the organic diisocyanate multimer include dimers and trimers of organic diisocyanates (TDI, etc.). The above-mentioned NCO group-terminated urethane prepolymer includes the aforementioned low-molecular-weight polyols (glycerin, trimethylolpropane, hexanetriol, etc.) and their alkylene oxide adducts with a hydroxyl value of 170 or more, preferably 280 or more, and an excess of Examples include reaction products with organic polyisocyanates (such as reaction products with 1 mol of trimethylolpropane and 3 mol of TDI). Preferred among these are aromatic diisocyanate polymers and NCO group-terminated urethane prepolymers. The composition of the present invention is a two-component adhesive composition consisting of (A) and (B). The blending ratio of (A) and (B) is OH/
The NCO equivalent ratio is usually 0.9 to 1.5, preferably 1.0 to 1.2. If the blending ratio is less than 0.9, curing will be insufficient and the desired performance will not be obtained, and if it exceeds 1.5, the peeling from the transfer material will become extremely difficult, making it impractical. When coating a substrate with the composition of the present invention, (A) and (B)
It is preferable to use these by diluting them with a solvent inert to the isocyanate group (ethyl acetate, methyl ethyl ketone, toluene, etc.) as necessary. Viscosity during coating is 35~
At 50% solids concentration, it is less than 100C.PS, and it takes about 10 to 25 seconds with a Zahn Cup #3 viscometer. In addition, the aforementioned catalysts such as dibutyltin dilaurate can be used to increase the curing speed. When producing metallic glossy paper using the adhesive composition of the present invention, for example, (A) and (B) are blended, and a transfer material with 0.01 to 0.1 μm of metal such as aluminum deposited thereon is deposited. Coat on the surface. As the transfer material, a corona-untreated biaxially stretched polypropylene film of about 20 μm can usually be used. The coating amount can generally be varied depending on the smoothness of the surface of the paper that is the base material, but is usually 1 to 10 g/m ² , preferably 3 to 8 g/m ² . A gravure coater is generally used for coating.
After drying the adhesive coating, the base paper and the adhesive-coated vapor-deposited film are bonded together using a laminator. As paper, art paper, coated paper, coated cardboard, etc. are usually used. This is left in a constant temperature room at 50 to 60°C for 40 to 50 hours to harden, and after curing, the transfer material film is peeled off. In this case, in order to peel the film smoothly without damaging it, the peel strength (sample width 50 mm, peeling speed 300 mm/min) measured with a normal tensile tester must be usually 100 g.
Below, it is necessary to use an adhesive whose weight is preferably 50 g or less. When the composition of the present invention is used in the production of a metallic luster coating by a transfer method, it is easily peeled off, the transfer of the deposited film is good, and it has excellent metallic luster.
In addition, the deposited film has excellent hardness and tensile strength, and also has other properties required for this type of glossy paper, such as water resistance, heat resistance, and solvent resistance. Such performance cannot be obtained when using urethane adhesive compositions other than those of the present invention, such as those using polyols that are not urethanized. The metallic glossy paper obtained using the composition of the present invention is useful for light packaging such as packaging for cigarettes and cosmetics, paper bags for snacks, and labels. The present invention will be explained below with reference to Examples. Example 1 A composition of the present invention consisting of the following (A) and (B) was produced. (A) Polypropylene glycol (average molecular weight 400)
Hydroxyl-terminated urethane prepolymer (B) obtained by reacting a mixture of 1 mole and 3 moles of a propylene oxide adduct of trimethylolpropane (average molecular weight 400) with diphenylmethane diisocyanate at an OH/NCO equivalent ratio of 1.8. Diisocyanate trimers (A) and (B) are mixed so that the OH/NCO equivalent ratio is 1.0, diluted with ethyl acetate to a solid content of 40%, and applied to a vapor-deposited film under the following conditions. After processing and drying, the substrates were bonded together and cured, and then the film and the substrate to which the vapor deposited film was transferred were peeled off to obtain a metallic glossy coating. The results are shown in Table 1. Transfer material: Biaxially oriented polypropylene film 20μ Deposited metal: Aluminum Deposited film thickness: Corona treated surface 0.03 to 0.05μ Base material: Coated paper 64g/m ² Adhesive coating method: Coated the deposited surface with a gravure coater Amount of adhesive applied: 5 g/m ² Curing conditions: 55°C x 48 hours Example 2 A composition of the present invention consisting of the following (A) and (B) was produced. (A) Polypropylene glycol (average molecular weight 200)
Hydroxyl-terminated urethane prepolymer (B) trimethylolpropane obtained by reacting a mixture of 1 mole of propylene oxide adduct of glycerin (average molecular weight 600) with 2 moles of diphenylmethane diisocyanate at an OH/NCO equivalent ratio of 2.0. NCO obtained by reacting 1 mole with 3 moles of tolylene diisocyanate
Group-terminated urethane prepolymers (A) and (B) were blended and coated under the same conditions as in Example 1.
A shiny metallic coating was obtained by lamination and peeling. The results are shown in Table 1. Comparative Example 1 A urethane adhesive conventionally used for dry lamination was used as an adhesive composition, and coating, lamination, and peeling were performed under the same conditions as in Example 1 to obtain a metallic glossy coating. The results are shown in Table 1. (A) Component Polybond AY-651A (Sanyo Chemical Industries, Ltd.
Co., Ltd.) (B) Component Polybond CA-110 (Sanyo Chemical Industries, Ltd.) The blending ratio of (A) and (B) is an OH/NCO equivalent ratio of 1.0. Comparative Example 2 Using an adhesive composition consisting of the following (A) and (B),
Coating, bonding, and peeling were performed under the same conditions as in Example 1. The results are shown in Table 1. (A) Polypropylene glycol (average molecular weight 200)
A mixture of 1 mole and 2 moles of a propylene oxide adduct of glycerin (average molecular weight 400) (B) NCO group-terminated urethane polymer obtained by reacting a polyether triol with an average molecular weight of 1000 and tolylene diisocyanate with an excess of NCO (A) The blending ratio of (B) and OH/NCO equivalent ratio is 1.0. Comparative Example 3 Using an adhesive composition consisting of the following (A) and (B),
Coating, bonding, and peeling were performed under the same conditions as in Example 1. The results are shown in Table 1. (A) Polypropylene glycol (average molecular weight
3000) and a mixture of 1 mole of propylene oxide adduct of glycerin (average molecular weight 3000) and diphenylmethane diisocyanate.
Hydroxyl-terminated urethane prepolymer (B) obtained by reacting at an OH/NCO equivalent ratio of 2.0 NCO obtained by reacting 1 mole of trimethylolpropane with 3 moles of triresin isocyanate
The blending ratio of the terminal urethane prepolymers (A) and (B) is 1.0 in terms of OH/NCO equivalent ratio. Example 3 Using the composition of the invention of Example 2, as a substrate
Transfers were carried out under the same conditions except that 320 g/m ² coated cardboard was used. The results are shown in Table 1. Comparative Example 4 Transfer was carried out under exactly the same conditions as in Example 3 using a moisture-curing urethane varnish [Samplen C-800K (Sanyo Chemical Industries, Ltd.)] as an adhesive composition. The results are shown in Table 1. 【table】

Claims (1)

[Scope of Claims] 1. A mixture of polyether diol with an average molecular weight of 200 to 2000 and polyether triol with an average molecular weight of 200 to 2000, and the average number of functional groups of hydroxyl groups per molecule is 2.4 to 2.9 ( a) and aromatic diisocyanate (b) with an OH/NCO equivalent ratio.
A two-component transfer method for producing metallic glossy coatings consisting of a hydroxyl-terminated urethane prepolymer (A) obtained by reacting in the range of 1.3 to 2.0 and an organic polyisocyanate (B) having aromatic isocyanate groups at both ends. Mold adhesive composition. 2. The composition according to claim 1, wherein (A) has a hydroxyl value of 50 to 200. 3. The composition according to claim 1 or 2, wherein (B) is a compound of an aromatic diisocyanate and a polyol. 4. The composition according to claim 1 or 2, wherein (B) is a dimer or trimer of an aromatic diisocyanate.