JPH0320376A - Coating composition - Google Patents

Abstract

PURPOSE:To obtain the subject compsn. providing a coating film with excellent wear resistance and excellent adhesive properties with a substrate by compounding a specified NCO group-contg. polyurethane with a specified amt. of an aminosilicone. CONSTITUTION:An NCO group-contg. urethane prepolymer prepared by reacting a mixture of a polyester diol (e.g. polyethylene adipate) and a polyether diol (e.g. polyoxypropylene glycol) with a diisocyanate (e.g. 4,4-diphenylmethane diisocyanate) is reacted with a low mol.wt. diol (e.g. 1,6-hexanediol) to form an NCO group-contg. polyurethane, which is then compounded with an aminosilicone [e.g. a compd. of the formula (wherein R is a 1-6C alkyl; (l) is 2-20; the amine equivalent is 500-10,000; (m) and (n) are determined by the amine equivalent) at a molar ratio of the amino group to the NCO group of 0.7-1.3.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a paint assembly that can be applied to rubber products, Hewei resin products, etc.

[Conventional technology]

Conventionally, natural rubber (NR), styrene-butadiene copolymer rubber (SBR), butadiene rubber (BR), isoptylene-isoprene copolymer rubber (IIR), chloroprene rubber (CR), acrylonitriloptadiene copolymer rubber (NBR), isoprene rubber (IR), ethylene-propylene-diene copolymer rubber (EPDM),
Nylon-based, epoxy-based, acrylic, and acrylic resins are used for surface coating of ethylene-propylene copolymer rubber (EPM), fibers such as cotton and rayon, and synthetic resins such as ABS resin and PS resin. Resin-based paints such as ethylene-based resins or rubber-based paints such as BR, CR, and SBR are used.

[Problem to be solved by the invention]

The above-mentioned conventional resin-based paints and rubber-based paints have problems in that they have poor adhesion to objects to be coated, and the resulting paint films have poor abrasion resistance. An object of the present invention is to provide a paint composition whose resulting coating has excellent abrasion resistance and good adhesion to the object to be coated.

[Means to solve the problem]

In order to achieve the above object, the present invention uses isocyanate groups obtained by reacting a low molecular weight diol with a urethane prepolymer having an isocyanate group, which is obtained by reacting a mixture of a polyester diol and a polyether diol with a diisocyanate. A method is adopted in which the main silicone is blended in an amount such that the molar ratio of amino groups (-NH2>/isocyanate groups (-NCO)) is 0.7 to 1.3 to the polyurethane having the following.

[Detailed explanation of means]

First, polyurethane having isocyanate groups will be explained. Examples of the polyester diol for producing the urethane brebolymer used in the present invention include ethylene glycol, propylene glycol, butylene glycol, pentanediol, hexanediol, octanediol, decanediol, neopentyl glycol, and the above diols. One or a mixture of two or more diols having double bonds or triple bonds and one or more carboxylic acids such as adipic acid, succinic acid, maleic acid, maleic anhydride, fumaric acid, phthalic acid, phthalic anhydride, etc. A polyester diol having a hydroxyl group at the end, which is synthesized by reacting a mixture of two or more types, can be used. As the polyether diol, polyoxyethylene glycol (PEG), polyoxypropylene glycol (PPG), polytetramethylene oxide glycol, etc. can be used. These polyester diols and polyether diols are used in combination. The mixing ratio of polyester diol and polyether diol can be set at an appropriate ratio over a wide range. The diisocyanates include 4.4'-diphenylmethane diisocyanate (MDI), 4.4''-diphenyl diisocyanate, 4.4'-diphenyl ether diisocyanate, 2.2-bis(4'-isocyanate phenyl)propane, 2. .4-Tolylene diisocyanate} (2.4-TDI), 2.4-TDI and 2.6-T
mixture with DI, isophorone diisocyanate (IPD
I>, bis(isocyanatomethyl)benzene, hexamethylene diisocyanate, hydrogenated MDI, hydrogenated 2.4-
TDI, hydrogenated2,4-TDI and hydrogenated2. Mixtures with 6-TDI, 1,5-naphthalene diisocyanate, etc. can be used. This diisocyanate is reacted with the mixture of the polyester diol and polyether diol. At that time, the ratio of the above mixture and diisocyanate used is hydroxyl group (-0H): isocyanate group (-
The molar ratio of N GO) is preferably in the range of 1:2 to 10. If the ratio of isocyanate groups is less than 2, the polyurethane itself becomes too soft and is likely to be inappropriate as a paint;
If it exceeds 0, the polyurethane itself becomes too hard and brittle, and is likely to be rejected as a paint. Next, the low molecular weight diol has a function as a curing agent or a quenching agent for the above-mentioned urethane prebolymer, such as ethylene glycol, propylene glycol, 1,4-butanediol, 1.3
- One or two of butanediol, 2,3-butanediol, diethylene glycol, dipropylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neobentyl glycol, etc.
I! Mixtures of the above can be used. This low molecular weight diol is added to the reaction product of the mixture of polyester diol and polyether diol and diisocyanate. If the ratio of its use increases, the ratio of hydroxyl groups will exceed the ratio of isocyanate groups, and polyurethane with terminal hydroxyl groups will be used. do. This polyurethane having an isocyanate group is produced by first reacting a mixture of a polyester diol and a polyether diol with a diisocyanate to synthesize a urethane prepolymer having an isocyanate group, as described above.
It is obtained by reacting the reactant with the low molecular weight diol. At this time, a solvent may be used if desired. The same solvents include benzene, toluene, xylene, ethylbenzene,
Trichlorethylene, ethylene chloride, dimethylformamide (DMF), dimethyl sulfoxide, methyl ethyl ketone, athene, methyl isopropyl ketone, methyl isobutyl ketone, methyl acetate, ethyl acetate, isopropyl acetate, n-butyl acetate, isobutyl acetate, Examples include anisole and tetrahydrofuran. Next, the main silicone to be blended into the above polyurethane will be explained. As this amino silicone, for example, those having the following structures can be used. In the above formula, R represents an alkyl group having 1 to 6 carbon atoms, and 1 represents an integer of 2 to 20. In addition, the ξ an equivalent of amino silicone is 500
A range of 10,000 to 10,000 is preferable. Note that mSn is determined based on this amine equivalent. This main silicone has a function as a curing agent for the polyurethane, and its blending ratio with respect to the polyurethane is as follows:
The molar ratio of amino groups (-NH2) in the amino silicone/isocyanate groups (-NGO) in the polyurethane is in the range of 0.7 to 1.3. When this molar ratio is less than 0.7 or more than 1.3, w! The adhesion of the i-film to the coated object decreases. As a method for preparing the paint composition of the present invention, for example, the polyester diol, polyether diol, diisocyanate and solvent are appropriately selected and mixed, and the mixture is reacted in dry nitrogen gas at 80°C for 3 hours to form an isocyanate group. Use urethane brevolimer. Vt, low molecular weight diol and a solvent were added to the urethane brebolymer, and the mixture was further heated for 30 minutes in dry nitrogen gas.
The reaction is carried out for a minute to form a polyurethane with isocyanate groups at the ends. Next, amino silicone is added to the polyurethane in an amount such that the molar ratio of main group/isocyanate group is 0.7 to 1.3, and a solvent is further added to adjust the viscosity to a value suitable for coating.

[Effect]

By employing the above-mentioned method, a specific property obtained by reacting a low molecular weight diol with a urethane prepolymer obtained by reacting a diisocyanate with a mixture of a polyester diol and a polyether diol and the characteristics such as lubricity possessed by the silicone as a main component. Due to the properties such as rigidity of high molecular weight polyurethane having a structure, the abrasion resistance of the resulting coating film is improved, and the coating film is It is assumed that this improves the adhesion between the paint and the object to be coated.

[Examples 1 to 12 and Comparative Examples 1 to 5] Examples embodying the present invention will be described below in comparison with comparative examples. In each example and comparative example, parts by weight are simply expressed as parts. First, the object to be coated is a vulcanized product as shown below. That is, the vulcanizate contains EPDMI O O parts, carbon black 70 parts,
A composition consisting of 35 parts of mineral oil, 7 parts of zinc oxide, 2 parts of stearic acid, 2 parts of vulcanization accelerator, and 1.5 parts of sulfur was vulcanized at 160°C for 30 minutes. In addition, a wear resistance test was conducted using the following method, and wear resistance was evaluated by wear loss. Testing machine: Taper type rotary presser (manufactured by Toyo Seiki Seisakusho Co., Ltd.) Test conditions: Wear wheel: H-22, Load: 1 kg, Wear rotation speed: 60 rp+s, Sample size: 100 sm x 100 mm, Number of wear: 21,000 times. For the mixture of polyester diol and polyether diol shown, each diisocyanate was mixed in a solvent, and this was heated at 80°C in a stream of dry nitrogen.
It was heated for 3 hours. A low molecular weight diol and a solvent were added to this reaction solution, and the mixture was heated at 80°C for 20 minutes in a stream of dry nitrogen.
As a result, the desired polyurethane was obtained. Back-1 The abbreviations in Front-1 have the following meanings. PED: Polyether diol PESD: Polyester diol DI-: Diisocyanate DO: Low molecular weight diol PPG 1000: Polyoxypropylene glycol PPG with a number average molecular weight of 1000 PPG 2000: Polyoxypropylene glycol PPG with a number average molecular weight of 2000 3000: Polyoxypropylene glycol with a number average molecular weight of 3000 Borioxypropylene glycol PI! A 1000: Polyethylene adipate PI with a number average molecular weight of 1000! A 2000: Polyethylene adipate with a number average molecular weight of 2000 PEA 3000: Polyethylene adipate with a number average molecular weight of 3000 PB^2000: Polyethylene adipate with a number average molecular weight of 2000 PEB^iooo: Polyethylene butylene adipate PI with a number average molecular weight of 1000! BA2000: Polyethylene butylene adipate PI with a number average molecular weight of 2000! Sel000: Polyethylene sebacate with a number average molecular weight of 1000 MDI: 4.4'-diphenylmethane diisocyanate TDI j Tolylene diisocyanate Tr: }Lichlorethylene TI ・Toluene Bz: Benzene xy: Xylene 1.5-HD: t. 6-hexanediol 1+4
-BD: t. 4-Butanediol EG: Ethylene glycol DMP: Dimethyl formamine/DNSO: Di-methyl sulfoxide (Example 1~
12) Next, a predetermined amount of amino silicone shown in Table 2 below was blended with the above polyurethane to obtain a paint composition. This paint composition was applied to the object to be coated, dried at 80°C for 20 minutes, and then subjected to the abrasion resistance test. The results are also shown in Table 2. Table-2 The abbreviations in Table-2 have the following meanings. Polyurethane represents those shown in Table 1 above. The main types of silicone are as follows. (a): Viscosity 1
700 centistokes (cst) (25℃),
Amine equivalent: 3800 (b): Viscosity: 90 cst (25°C), amine equivalent: 4
400《C》: Viscosity 90cst (25°C), ξan equivalent 880
0 <<d>>: Viscosity 3500 cst (25°C), amine equivalent 3800 In addition, the molar ratio represents the molar ratio of amino group/isocyanate group. As can be seen from Table 2 above, the paint films obtained with the paint compositions of each example had abrasion loss of 8.7 to 10. OB and a small amount. The reason why the coating films obtained from the paint composites of each example exhibit such excellent abrasion resistance without impairing the material properties of the coated object is due to the lubricity and other properties of amino silicone and the polyester base. This is presumed to be due to the properties such as rigidity of a high molecular weight polyurethane with a specific structure, which is made by reacting a urethane prepolymer made by reacting a mixture of a diol and a polyether diol with a diisocyanate, and then a low molecular weight diol. Furthermore, the coating films obtained in each example have excellent adhesion to the object to be coated. This is presumed to be due to the effect of the isocyanate group of the above-mentioned polyurethane or the main group of the aminosilicone. (Comparative Examples 1 and 2) Next, as a comparative example, the abrasion resistance was evaluated in the same manner as in the above example in a case where the blending ratio of the main silicone was outside the range of the present invention. The results are shown in Table 3. Table 3 As can be seen from Table 3 above, when the molar ratio of main silicone is smaller than the range of the present invention (Comparative Example 1) or larger (Comparative Example 2), the wear loss becomes very large. I end up. Next, as another comparative example, coatings were formed on the following three types of paint assemblies and the abrasion loss was measured. (Comparative Example 3) A coating composition consisting of 100 parts of liquid polybutadiene (product name: Idemitsu Seal AB-700W, manufactured by Idemitsu Petrochemical Co., Ltd.) and part MDIIO was applied to the object to be coated, and dried and cured. This coating film was subjected to an abrasion resistance test in the same manner as in the previous example. As a result, the wear loss was 2 2 5 2 m
g/100.0 times. (Comparative Example 4) A paint composition consisting of 100 parts of liquid polybutadiene (trade name: Idemitsu Seal AB-100, manufactured by Idemitsu Petrochemical Co., Ltd.) and 110 parts of MD was applied to the object to be coated, and dried and cured. This coating film was subjected to an abrasion resistance test in the same manner as in the previous example. As a result, the wear loss was 2 290 mg.
/1000 times. (Comparative Example 5) A chloroprene-based rubber paint (74% toluene solution, trade name Bond G2, manufactured by Konishi Co., Ltd.) was applied to the object to be coated, and dried and cured. This coating film was subjected to an abrasion resistance test in the same manner as in the previous example. As a result, the wear loss was 6
9 1 mg/1000 doses. Comparative example 3 above
The coating film obtained from the paint assembly of No. 5 has an abrasion loss of 691
It is large, ~2290+++g, and it can be seen that the wear resistance is poor. As mentioned above, the paint assembly of the present invention has excellent abrasion resistance and adhesion, so it can be used for rubber products, plastic products,
For example, it is suitably used for automobile weather strips, glass runs, adhesive tapes, etc.

【Effect of the invention】

Claims (1)

[Claims] 1. A polyurethane having an isocyanate group obtained by reacting a low molecular weight diol with a urethane prepolymer having an isocyanate group obtained by reacting a mixture of a polyester diol and a polyether diol with a diisocyanate, Group (
-NH_2)/isocyanate group (-NCO) in an amount such that the molar ratio is 0.7 to 1.3.