JP3537152B2 - Composition for coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composition for coating using a saturated polyester resin.
The present invention relates to a coating composition having excellent adhesion to a substrate such as polyethylene terephthalate (PET) and having good solvent resistance and heat resistance.

[0002]

2. Description of the Related Art In recent years, PET has been widely used in the molding of sheets, bottles, etc.
There has been an increasing demand for lamination between T or other resins or printing on the molded product. Normally, PET is used in applications such as printing on PET composite films and PET containers.
Surface treatment is performed because it is necessary to improve the adhesiveness of the surface with the adhesive and the adhesiveness with the ink (hereinafter, collectively referred to as adhesiveness). Specifically, PET
There are a method of activating the surface by corona discharge treatment, plasma treatment, ultraviolet irradiation treatment, etc., a method of treating the PET surface with various chemicals, and a method of providing a primer layer or a coating layer on the PET surface.

[0003]

However, the method of
The initial adhesion improves, but decreases over time. In the method (1), handling such as a treatment procedure of chemicals is complicated. Conventionally, water-based and solvent-based methods have been used, and the former method has the advantages of being non-polluting and the latter having good drying properties after coating. There is still a need for improvement in terms of properties and adhesion . That is, when the coated PET base material is stored in summer, heat resistance (blocking resistance) of at least 60 to 80 ° C. is required so that the coating surface does not cause blocking, and printing or the like is performed on the coating surface. In this case, solvent resistance to solvent-based ink and the like is also required.

The inventors of the present invention have conducted intensive studies to solve such a problem, and as a result, have found that terephthalic acid and / or isophthalic acid are 50 to 85 mol% and alkyl dicarboxylic acid having 2 to 8 carbon atoms in the alkyl group. An acid component consisting of 15 to 50 mol% and 30 to 50 mol% of 1,4-butanediol;
A saturated polyester resin obtained by reacting a glycol component composed of 20 to 40 mol% of 1,6-hexane glycol and 20 to 50 mol% of cyclohexane dimethanol is used to obtain 50 to 90 wt% of toluene and 10 to 50 wt% of ketone.
It has been found that a coating composition dissolved in a mixed solvent having the following composition has excellent adhesion to a PET substrate and good solvent resistance and heat resistance, and has completed the present invention. Hereinafter, the present invention will be described in detail.

As the acid component constituting the polyester resin of the present invention, the above terephthalic acid and / or isophthalic acid are contained in an amount of 50 to 85 mol%, preferably 60 to 80 mol%,
Alkyl dicarboxylic acid 1 having 2 to 8 carbon atoms in the alkyl group
It is 5 to 50 mol%, preferably 20 to 40 mol%.
Here, terephthalic acid and isophthalic acid may be used either singly or in combination of two, but preferably used in combination of two in view of solution stability. In this case, the molar ratio of terephthalic acid / isophthalic acid is 3 to 3. 7 is suitably selected. The alkyl dicarboxylic acids having 2 to 8 carbon atoms in the alkyl group include succinic acid, adipic acid, azelaic acid, sebacic acid and the like, and one of them is suitably selected and used. As the glycol component, 1,4-butanediol 30 to 50 mol%, 1,6-hexane glycol 2
0-40 mol%, cyclohexanedimethanol 20-5
0 mol%.

Here, if the amount of terephthalic acid and / or isophthalic acid is less than 50 mol%, there is no heat resistance and the adhesion is reduced, and if it exceeds 85 mol%, the solution stability of the coating agent is reduced. Becomes defective. If the amount of the alkyl dicarboxylic acid having 2 to 8 carbon atoms in the alkyl group is less than 15 mol%, the solution stability of the coating agent will be poor and the adhesion will be reduced. Conversely, if it exceeds 50 mol%, the solvent resistance will be reduced. . Also, 1,
If the amount of 4-butanediol is less than 30 mol%, the adhesion will decrease, and if it exceeds 50 mol%, the solution stability of the coating agent will be poor. If the amount of 1,6-hexane glycol is less than 20 mol%, the solution stability of the coating agent will be poor, and if it exceeds 40 mol%, the adhesion will decrease. If the amount of cyclohexanedimethanol is less than 20 mol%, the solution stability of the coating agent will be poor, and
If it exceeds 0 mol%, the adhesion will be reduced.

Further, in the present invention, the polyester resin having the above composition is mixed with 50 to 90% by weight of toluene, preferably 60 to 90% by weight.
80% by weight and 10 to 50% by weight of ketone, preferably 2%
It is characterized in that it is dissolved in a mixed solvent of 0 to 40% by weight, and other than the mixed solvent, it is not possible to sufficiently improve the adhesion and sufficiently exhibit the stability of the solution, and the object of the present invention cannot be achieved. . The ketone referred to here is methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone,
It means ketones such as isophorone, and among them, methyl ethyl ketone and methyl isobutyl ketone are preferably used. Here, the mixing ratio of the polyester resin and the mixed solvent is preferably 5/95 to 50/50 (weight ratio), and more preferably 10/90 to 30/70. When the amount of the polyester resin increases, the solution stability of the coating agent becomes poor. On the other hand, when the amount decreases, the number of application times of the coating agent increases, resulting in poor efficiency. Also, a small amount of a polyester resin solvent such as xylene, ethyl acetate, butyl acetate, ethyl cellosolve, cellosolve acetate, etc. can be added to the mixed solvent as long as the effects of the present invention are not impaired.

The polyester resin of the present invention is produced by condensation polymerization of the above-mentioned acid component and glycol component. The heat of crystallization and melting of the produced polyester resin is as follows:
It is preferably from 5 to 30 J / g (measured by a differential scanning calorimeter), more preferably from 7 to 20 J / g. If the crystallization heat of fusion is low, the cohesive force of the polyester resin is reduced. Conversely, if it is high, the degree of crystallinity increases, and it becomes hardly soluble in a solvent. Further, the molecular weight is preferably about 7000 to 30,000 (measured value by a terminal group method), and more preferably 10,000 to 25,000. When the molecular weight is low, the cohesive force of the coating agent is not provided, and the adhesion is reduced. Conversely, if it is too high, it becomes hardly soluble in the solvent. The flow starting point is preferably from 80 to 160 ° C. (measured by a Koka flow tester), and more preferably from 90 to 150 ° C.
C is preferred. If the flow starting point is low, the heat resistance is reduced, and if it is high, it becomes hardly soluble in the solvent.

The method for producing the polyester resin of the present invention as described above is not particularly limited, and it can be carried out according to a known ordinary method. For example, a predetermined amount of terephthalic acid, isophthalic acid, succinic acid or adipic acid or azelaic acid or sebacic acid, 1,4-butanediol, 1,6-hexaneglycol, cyclohexanedimethanol is directly esterified simultaneously or stepwise. Or a method of performing polymerization after transesterification reaction, or the like. Any known various catalysts, stabilizers, modifiers or additives may be used in the polymerization or transesterification. The polyester resin obtained by such a method is obtained by a known method using the above toluene-
The composition for coating of the present invention is dissolved in a mixed solvent of ketone.

[0010]

The coating composition of the present invention is used for surface modification of plastics, especially PET sheets, films, bottles, etc., or for bonding such films or sheets to each other or to wood, metal plate, paper, leather or the like. It is very useful as a coating agent for anchor coating at the time of printing on PET or PET surfaces, and various substrates coated with the coating agent can be used for a wide range of materials such as packaging materials, recording materials, magnetic recording materials, adhesive / adhesive sheets, display sheets, etc. It can be used for various applications.

[0011]

The present invention will be specifically described below with reference to examples. In the examples, “%” means on a weight basis unless otherwise specified. Example 1 4 equipped with a stirrer, a rectification column, a nitrogen inlet tube and a vacuum device
Acid component (65 mol% terephthalic acid, 10 mol% isophthalic acid, 25 mol% adipic acid)
1 mol, glycol component (1,4-butanediol 38
Mol%, 26 mol% of 1,6-hexane glycol, 36 mol% of cyclohexanedimethanol) and 0.001 mol of dibutyltin oxide as a catalyst, and an esterification reaction was carried out at 180 to 240 ° C. -Butyl titanate (0.001 mol) was added, and a polycondensation reaction was carried out at 250 ° C. under a reduced pressure of 1 Torr or less.
36 ° C., molecular weight of 2,000 with heat of crystallization of 15.9 J / g
0 polyester resin was obtained. Further, 20 parts by weight of the resin was dissolved in 80 parts by weight of a mixed solvent of 80% by weight of toluene and 20% by weight of methyl ethyl ketone to obtain a coating composition.

Examples 2 to 5 and Comparative Examples 1 to 9 According to the resin and solvent compositions shown in Tables 1 and 2, a coating composition for a polyester resin was obtained according to Example 1. Tables 2 and 3 show resin properties and coating agent properties of the coating compositions obtained in Examples and Comparative Examples.

[0013]

Table 1 Polyester resin acid component (mol%) glycol component (mol%) TPA IPA AdA SuAn AzA SebA 1,4BG 1,6HG CHDM Example 1 65 10 25 00 00 38 26 36 〃 260 10 0 300 0 0 38 26 36 〃 370 10 00 0 200 0 38 26 36 〃 470 10 00 0 20 38 38 26 36 ５ 5 65 10 25 0 0 0 45 27 28 Comparative Example 1 355 60 0 0 0 038 38 36 275 15 100 000 38 26 36 〃 365 10 25 000 020 40 40 ４ 465 10 25 000 050 5525 20 ５ 5 65 10 25 000 050 50 15 35 〃 65 65 10 250 0 0 35 45 20 〃 7 65 10 25 0 0 0 45 40 15 〃 8 65 10 25 0 0 0 38 26 36 〃 9 65 10 25 0 0 0 38 2 36

Note) Abbreviations are as follows. TPA; terephthalic acid, IPA; isophthalic acid, AdA; adipic acid, SuAn; succinic acid, AzA; azelaic acid, Seba; sebacic acid, 1,4BG; 1,4-butanediol, 1,6HG; 1,6-hexane glycol, CHDM; 1,4-cyclohexanedimethanol, Tol; toluene, MEK; methyl ethyl ketone,

[0015]

Table 2 Resin properties Mixed solvent melt viscosity Flow starting point Heat of crystallization Molecular weight (% by weight) (Poise) (° C) (J / g) Tol MEK Example 1 960 136 15.9 20000 80 20 20 1090 129 14.3 22000 80 20 ３ 3 1010 140 16.3 19000 80 20 ４ 4 1180 142 17.0 19000 80 20 ５ 5 1060 118 14.0 20000 80 20 Comparative example 1 1070 64 6.5 20000 80 20 20 2 1200 154 22.1 22000 80 20 ３ 3 1040 93 16.7 20,000 80 20 〃 4 1110 146 17.1 22000 80 20 〃 5 1010 144 15.3 20000 80 20 〃 6 1150 121 18.6 22000 80 7 980 132 19.3 20,000 80 20 ８ 8 960 136 15.9 20,000 40 60 ９ 9 960 136 15.9 20,000 95 5

[0016]

[Table 3] Coating agent characteristic adhesion Solvent resistance Heat resistance Stability Drying Example 1 ○ ○ ○ ○ ○ 〃2 ○ ○ ○ ○ ○ 〃3 ○ ○ ○ ○ ○ 〃4 ○ ○ ○ ○ ○ 〃5 ○ ○ ○ ○ ○ Comparative Example 1 ○ × × ○ × 〃 2 × ○ ○ × ○ 〃 3 ○ △ ○ ○ × 〃 4 ○ ○ ○ △ ○ 〃 5 ○ ○ ○ × ○ 〃 6 ○ × ○ ○ × 〃 7 ○ × ○ ○ × ８ 8 ○ ○ ○ × ○ 〃 9 ○ ○ ○ × ○

Note) Measuring method: Melt viscosity increasing type flow tester (CFT-500 manufactured by Shimadzu Corporation)
C), nozzle: φ1 mm × 1 cm, load: 30 k
g, temperature; measured at 190 ° C.・ High flow start point type flow tester (CFT-500 manufactured by Shimadzu Corporation)
C), nozzle: φ0.5 mm × 1 mm, load: 2
The temperature was raised at a rate of 3 ° C./min from 40 ° C. under the condition of 0 kg, and the temperature at which the resin began to flow was measured. -Crystallization heat of fusion differential scanning calorimeter (PerkinElmer DSC-7)
The temperature was raised from -50 to 180 ° C at a rate of 20 ° C / min, and the heat of fusion was measured. -According to the molecular weight end group method.

A coating composition is applied to the surface of an adhesive substrate (PET) to form a coating film (10 μm), and then JIS K5 at room temperature.
From above make squares of 100 / cm ² the coating film in accordance with the cross-cut adhesion test of 400, after pressure sufficiently rolling adhered cellophane tape was left by once peeling cellophane tape onto the substrate squares The adhesion was examined by the number of eyes. Evaluation criteria are
As follows. ○ --- 80 or more per 100 squares remained. × −−− 未 満 Less than 80 remained. Solvent Resistance The surface of the coating film prepared in the same manner as in the evaluation of adhesion was rubbed with a cotton swab impregnated with methanol, and the number of times until the PET substrate was exposed was examined. The evaluation criteria are as follows. ○ −−− 50 times or more Δ −−− 20 times or more to less than 50 times × −−− less than 20 times ・ Heat resistance (blocking resistance) A PET substrate coated with 60 ° C. PE which had been cured at room temperature on the coated surface immediately after taken out to room temperature after 4 hours
T film (100μ) bonded (pressure: about 0.1
kg / cm ² × 10 sec) The blocking property was examined. The evaluation criteria are as follows. ○ --- The PET film does not adhere. × −−− 付 着 Adheres.

Stability The composition for coating is adjusted to a solid content of 10% (dissolved in a solvent of toluene / methyl ethyl ketone = 4/1) and left at 20 ° C. and 65% RH for 1 month to form a gel. I checked the condition. ○ --- No abnormality. Δ ---- 1 Gel was generated in one week to less than one month. X: Gel is generated in less than one week. The coating composition adjusted to a solid content of 10% is applied (100 g / cm ² ) to a dry PET substrate, and 100 ° C. × 1
After drying for 20 sec, the adhesion to the PET film (100 μ) was examined immediately after the removal, in the same manner as the heat resistance evaluation. ○ --- The PET film does not adhere. × −−− 付 着 Adheres.

[0020]

The coating composition of the present invention can be used for surface modification of plastics, especially PET films, sheets, bottles and the like, or for adhesion of the films and sheets to each other or to wood, metal plate, paper, leather and the like. It is very useful as a coating agent for anchor coating when printing on PET or PET surfaces.

Claims (2)

(57) [Claims] 1. Terephthalic acid and / or isophthalic acid 5
An acid component consisting of 0 to 85 mol%, 15 to 50 mol% of an alkyldicarboxylic acid having an alkyl group having 2 to 8 carbon atoms,
A saturated polyester resin obtained by reacting a glycol component consisting of 30 to 50 mol% of 4-butanediol, 20 to 40 mol% of 1,6-hexane glycol, and 20 to 50 mol% of cyclohexane dimethanol is converted into toluene 50 to 50 mol%.
A coating composition dissolved in a mixed solvent having a composition of 90% by weight and 10 to 50% by weight of a ketone. 2. The coating composition according to claim 1, wherein the mixing ratio of the saturated polyester resin and the mixed solvent is 5/95 to 50/50 (weight ratio).