JPH0215575B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a modified polyester resin having excellent adhesion to metals, moisture resistance and corrosion resistance. BACKGROUND ART Saturated copolymer polyester resins have been used in various paints and adhesives because they have excellent flexibility, weather resistance, and adhesion to various materials. Among others, polyethylene terephthalate and its copolyester, soft and hard polyvinyl chloride, polycarbonate, ABS resin,
It is known to have excellent adhesion to molded products of synthetic resins such as polyurethane resin. However, recently, studies have begun to consider laminating or coating the above synthetic resin on steel plates or steel pipes to give them superior aesthetics, durability, and post-processability. After coating or applying a primer, coating or lamination is performed. The saturated copolymerized polyester resin not only has excellent adhesion to the above synthetic resins, but also has excellent adhesion to iron, zinc, tin, aluminum, copper, and the like. Therefore, when laminating various synthetic resins on such metals, it is naturally possible to use a saturated copolymerized polyester resin as an undercoat. However, an example is shown in which a saturated copolymerized polyester resin is used as an undercoat. However, when a saturated copolymerized polyester resin is coated on a metal surface, either alone or in combination with various hardening agents, the moisture resistance is extremely poor, especially in the case of a clear coating film, and when left in hot water, the entire surface in contact with the metal peels off. As a result, it is not used in clear coating applications despite its other excellent properties. In view of these circumstances, the inventors of the present invention have conducted extensive studies on adhesives or coating agents that maintain the adhesive properties inherent to saturated copolyester polyester resins to various synthetic resins and have excellent moisture resistance and corrosion resistance to metals. As a result, the present invention was achieved. That is, in the present invention, the aromatic dicarboxylic acid component is
The reduced viscosity obtained by the reaction of an acid component containing 40 to 100 mol% and 60 to 0 mol% of a carboxylic acid component other than an aromatic dicarboxylic acid and an alcohol component containing at least one type of glycol has a reduced viscosity of at least 0.2. As described above, a compound having at least two isocyanate groups in the molecule is added to the saturated copolymerized polyester resin having a hydroxyl group at the end of the molecular chain, so that the isocyanate group is added to the hydroxyl group in the polyester resin.
After mixing and reacting at a ratio ranging from 0.8 to 5, 0.1 to 5 parts by weight of a silane cobbling agent having an amino group or a glycidyl group is added to the reaction product based on 100 parts by weight of the polyester resin. This is a method for producing a modified polyester resin, which is characterized by reacting at a certain ratio. The modified polyester resin of the present invention not only has significantly better water resistance and moisture resistance than unmodified saturated polyester resin, but also has increased heat resistance and adhesive strength, and also Corrosion resistance improves when the coating is metal. Further, the modified polyester resin of the present invention has extremely excellent storage stability when dissolved in an organic solvent even when trifunctional polyisocyanate is used as a raw material component. More specifically, the saturated polyester resin of the present invention has an aromatic dicarboxylic acid residue of at least 40 mol%, preferably at least 50 mol% of the acid component, and a reduced viscosity of at least 0.2, preferably 0.4 to 1.5. Acid value with hydroxyl group end
15-150 polyester resin. Examples of the aromatic dicarboxylic acid component include terephthalic acid, isophthalic acid, orthophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyldicarboxylic acid, and 5-sodium sulfoisophthalic acid. Carboxylic acid components other than aromatic carboxylic acid components include aliphatic dicarboxylic acids such as succinic acid, adipic acid, azelaic acid, sebacic acid, decamethylene dicarboxylic acid, and dimer acid, and alicyclic acids such as 1,4-cyclohexanedicarboxylic acid. Dicarboxylic acids, oxyacids such as p-(2-hydroxyethoxy)benzoic acid, cyclic lactones such as ε-caprolactone, etc. can be arbitrarily selected and used. The acid components include 40 to 100 mol% of terephthalic acid or terephthalic acid and isophthalic acid, and 60 mol% of dicarboxylic acids other than terephthalic acid and isophthalic acid.
It is preferable that it is 0 mol%. Glycol components include ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, polypropylene glycol, 1,4-butanediol, 1,
3-butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, 1,5-
pentanediol, 1,6-hexanediol,
N-methyldiethanolamine, 2-methyl 2-
It consists of one or more glycols such as dimethylaminomethyl 1,3-propanediol. As the glycol component, those consisting of ethylene glycol and neopentyl glycol are particularly preferred. In addition to the above components, trivalent or higher acid or trivalent or higher alcohol components such as trimellitic acid and trimethylolpropane may be added in an amount not exceeding 3 mol% based on the total acid component or total glycol component in the polyester resin. May be contained. The saturated polyester resin used in the present invention can be used after being dispersed or dissolved in water and/or an organic solvent. Suitable solvents include one or a mixed solvent of two or more of methylene chloride, 1,4-dioxane, methyl ethyl ketone, ethyl acetate, toluene, N,N-dimethylformamide, n-butyl cellosolve, water, and the like. If the aromatic dicarboxylic acid component as the acid component of the saturated polyester resin used in the present invention is less than 40 mol%, the cohesive force of the saturated polyester resin will be low, and therefore the adhesive strength will also be weak, so it is not suitable for the purpose of the present invention. Furthermore, when the reduced viscosity of the saturated polyester resin used in the present invention is less than 0.2, the storage stability of the modified polyester resin of the present invention decreases,
Significant thickening or gelation may occur during storage, and the cohesive force is also weak, resulting in a decrease in adhesive strength. The polyisocyanate compounds used in the present invention include tolylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, triphenylmethane diisocyanate, and/or combinations of these polyisocyanates with ethylene glycol, neopentyl glycol, Examples include addition reaction products with polyols such as methylolpropane. The ratio of the saturated polyester resin and the isocyanate compound is such that the equivalent ratio of the isocyanate group to the hydroxyl group in the saturated polyester resin is 0.8/1 to 5/1,
It is preferably added at a ratio of 1/1 to 3/1. When this equivalent ratio exceeds 5/1, it becomes difficult to control gelation during the reaction, especially when a trifunctional or higher functional polyisocyanate compound is used. Also
At the end of 0.8/1, the effect of adding the isocyanate compound is not seen. The silane coupling agent used in the present invention has a reactive group (methoxy group, ethoxy group, silanol group, etc.) that can chemically bond with an amino group or glycidyl group and an inorganic substance (glass, metal, silica sand, etc.) in its molecule.
It has the following. As a specific example, γ-
Glycidoxypropyltrimethoxysilane, β-
(3,4epoxycyclohexyl)ethyltrimethoxysilane, N-β-(aminoethyl)γ-aminopropylmethyldimethoxysilane, N-β-
(Aminoethyl) γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and the like. The amount of the silane coupling agent used in the present invention is 0.1 to 100 parts by weight of the saturated polyester resin.
It is preferable to add 5 parts by weight, but the optimum amount can be changed depending on the type of silane coupling agent and the amount of isocyanate compound added. The modified polyester resin of the present invention can be used as it is, but in addition, an amino resin as a crosslinking agent,
One or more compounds selected from the group of epoxy compounds and isocyanate compounds can be used in combination. Examples of amino resins include formaldehyde adducts of urea, melamine, and benzoguanamine, and alkylated products with alcohols having 1 to 6 carbon atoms. Further, if necessary, a favorable effect can be achieved by using formalin in combination. Epoxy compounds include bisphenol A diglycidyl ether and its oligomer, hydrogenated bisphenol A diglycidyl ether and its oligomer, orthophthalic acid diglycidyl ester, isophthalic acid diglycidyl ester,
Terephthalic acid diglycidyl ester, p-oxybenzoic acid glycidyl ester ether, tetrahydrophthalic acid diglycidyl ester, hexahydrophthalic acid diglycidyl ester, succinic acid diglycidyl ester, adipic acid diglycidyl ester, sebacate diglycidyl ester, ethylene Glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-
Butanediol diglycidyl ether, 1,6-
Hexanediol diglycidyl ether and polyalkylene glycol diglycidyl ethers, trimellitic acid triglycidyl ester, triglycidyl isocyanurate, 1,4-diglycidyloxybenzene, diglycidyl dimethylhydantoin, diglycidyl ethylene urea, diglycidyl propylene urea, glycerol Examples include polyglycidyl ether, trimethylolethane polyglycidyl ether, trimethylolpropane polyglycidyl ether, pentaerythritol polyglycidyl ether, and polyglycidyl ether of a glycerol alkylene oxide adduct. Furthermore, as isocyanate compounds, aromatic,
There are aliphatic and araliphatic diisocyanates, trivalent or higher polyisocyanates, low molecular compounds,
Any polymer compound may be used. Specific examples include the above-mentioned polyisocyanate compounds used to produce the modified polyester resin of the present invention or an excess amount of these isocyanate compounds;
For example, low-molecular active hydrogen compounds such as ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine, various polyether polyols, polyester polyols,
Examples include terminal isocyanate group-containing compounds obtained by reacting polymeric active hydrogen compounds such as polyamides. The isocyanate compound may be a blocked isocyanate. Examples of isocyanate blocking agents include phenols such as phenol, thiophenol, methylthiophenol, ethylphenol, cresol, xylenol, resorcinol, nitrophenol, and chlorophenol, oximes such as acetoxime, methyl ethyl ketoxime, and cyclohexanone oxime, methanol, and ethanol. , alcohols such as propanol and butanol, halogen-substituted alcohols such as ethylene chlorohydrin, 1,3-dichloro-2-propanol, t-butanol, t-butanol, etc.
- Tertiary alcohols such as pentanol and t-butanethiol, lactams such as ε-caprolactam, δ-valerolactam, γ-butyrolactam, and β-propyllactam, as well as aromatic amines and imides. , active methylene compounds such as acetylacetone, acetoacetate, and ethyl malonate, mercaptans, imines, ureas, diaryl compounds, sodium bisulfite, and the like. The blocked isocyanate can be obtained by subjecting the above-mentioned isocyanate compound and an isocyanate blocking agent to an addition reaction by a conventionally known appropriate method. The modified polyester resin of the present invention is obtained by first reacting a saturated polyester resin with an isocyanate compound and then reacting with a silane coupling agent. Although the reaction can be carried out by mixing in a molten state, the most desirable method is heating in an organic solvent. In order to obtain the modified polyester resin of the present invention, dibutyltin dilarate, triethylamine, etc. may be added as a catalyst for the reaction between isocyanate groups and hydroxyl groups. Further, the modified polyester resin may contain commonly used optional components such as a tackifier, a colorant, an ultraviolet absorber, and a filler. The modified polyester resin of the present invention has excellent adhesion to various synthetic resins and metals, and is also extremely excellent in moisture resistance and corrosion resistance. Hereinafter, the present invention will be specifically explained with reference to Examples. In the examples, the polyester resin and silane coupling agent used were as follows.

【table】

[Table] In the examples, parts simply refer to parts by weight. Example 1 Saturated copolymerized polyester resin shown in Table 1
100 parts of the solution was dissolved in 300 parts of methyl ethyl ketone, 10 parts of Coronate L (an adduct of 3 moles of toluene diisocyanate manufactured by Nippon Polyurethane Co., Ltd. and 1 mole of trimethylolpropane) was added, and the mixture was heated at 70°C for 4 hours. Next, 1 or 2 parts of a silane coupling agent having an amino group (Shin-Etsu Silicone KBM-603 or 403, manufactured by Shin-Etsu Chemical Co., Ltd.) was added, and the mixture was further heated for 1 hour. The obtained modified polyester resin solution was applied to a mild steel plate (manufactured by JIS G-3141 Japan Test Panel Industry Co., Ltd.) at a solid amount of 5 g/m ² using a wire bar, and after the solvent was evaporated, the coated surface and a soft vinyl chloride sheet were coated. (manufactured by C.I. Kasei Co., Ltd., Hama Plus 169-3S, thickness 0.2 mm) was thermocompressed for 10 seconds at 150° C. under a pressure of 2 kg/cm ² . The stability of the modified polyester resin solution and the 180 degree peel strength of the adhesive at 20°C were measured. The results are shown in Table 1. Comparative Example 1 In the case of the same saturated copolymerized polyester resin alone as in Example 1 (sample 5), in the case of mixing and reacting Coronate L with this saturated copolymerized polyester resin (sample 6), silane was added to this saturated copolymerized polyester resin. When reacting with a coupling agent (Sample 7)
The solution stability and the 180 degree peel strength of the adhesive at 20°C were measured in the same manner as in Example 1. The results are shown in Table 1.

[Table] ×: Gelation or significant increase in viscosity Example 2 The same modified polyester resin solution as Sample 4 of Example 1 was applied to a thickness of 5μ on the same mild steel plate as in Example 1, and after drying, unstretched polyethylene Layer terephthalate sheets (thickness 100μ) to produce 2kg/kg at 150℃.
Heat compression bonding was carried out for 10 seconds under a pressure of cm ² . The adhesive was immersed in saline solution at 40° C. for 7 days, and changes in adhesive strength and degree of rust generation at the cut portion were measured. The results are shown in Table 2. Comparative Example 2 When the polyester resin used in Sample 4 above was used alone (Sample 8), when this polyester resin was mixed with Coronate L and reacted (Sample 9), when this polyester resin was reacted with a silane coupling agent (Sample 10) The performance was tested in the same manner as in Example 2. The results are shown in Table 2.

【table】

Claims (1)

[Claims] 1 Aromatic dicarboxylic acid component is 40 to 100 mol%,
Carboxylic acid components other than aromatic dicarboxylic acids are 60~
The reduced viscosity obtained by the reaction of an acid component of 0 mol% with an alcohol component containing at least one type of glycol is at least 0.2, has a hydroxyl group at the end of the molecular chain, and has an acid value of 15 to 150. After mixing and reacting a compound having at least two isocyanate groups in the molecule with a saturated copolymerized polyester resin at a ratio of isocyanate groups to hydroxyl groups in the polyester resin in the range of 0.8 to 5, A method for producing a modified polyester resin, which comprises reacting the reactant with a silane coupling agent having an amino group or a glycidyl group in a proportion of 0.1 to 5 parts by weight per 100 parts by weight of the polyester resin.