JPH0341173A - Urethane coating composition - Google Patents

Abstract

PURPOSE:To prepare a coating compsn. with improved adhesiveness to vulcanized olefin rubber by compounding a hydroxyl-terminated urethane prepolymer with an isocyanate-terminated urethane prepolymer, both obtd. by reacting a specific high mol.wt. polyol component with an org. diisocyanate. CONSTITUTION:In preparing a coating compsn. obtd. by compounding a hydroxyl-terminated urethane prepolymer with a curing agent comprising an isocyanate-terminated urethane prepolymer, both prepolymers being obtd. by reacting a high-mol.wt. polyol component with an org. diisocyanate, the high-mol. wt. polyol component is made to contain 50-100mol% polyester polyol contg. a polycondensate of neopentyl glycol with a dibasic acid. As the rest of the high-mol.wt. polyol component, a polycarbonate polyol or polyethercarbonate polyol is pref.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention is applicable to various plastics such as nylon resin, polyester resin, polystyrene resin, acrylic resin, and polycarbonate resin, or styrene-butadiene copolymer rubber, polychloroprene rubber, Urethane coating compositions that have excellent adhesion to various products made of various rubbers such as polyisoprene rubber, especially ethylene-propylene vulcanized rubbers and olefin thermoplastic rubbers, as well as polypropylenes to which these rubbers are added. The present invention relates to a urethane coating composition that can be applied to products made of resin.

(Prior art and problems of the present invention) Ethylene-propylene vulcanized rubber and olefin thermoplastic rubber include natural rubber (NR), styrene-butadiene copolymer rubber (SBR), and polybutadiene rubber (BR).
), isobutylene-isopropylene copolymer rubber (IIR
), polychloroprene rubber (CR), acrylonitrile-butadiene copolymer rubber (NBR), polyisoprene rubber (IR), and other synthetic rubbers, it exhibits superior performance in terms of weather resistance, aging resistance, and ozone resistance. Furthermore, the operating temperature range is wide ranging from 150°C to 150'C.
It is a rubber material with excellent characteristics, and these rubbers are now used not only alone but also in a variety of ways, such as by adding them to other resins, such as polypropylene resin, and molding them into automobile bumpers. It has become.

However, since these rubber materials do not contain unsaturated bonds or polar groups in their main chains, the paint easily peels off, making it difficult to paint these rubber materials.

Conventionally, many countermeasures have been attempted to address these drawbacks. For example, ■ polishing the surface with a wire brush, sandpaper, etc., ■ subjecting it to corona discharge treatment, ■ immersing it in concentrated sulfuric acid, ■ treating it with a mixed solution of organic monocarboxylic acid and phosphoric acid, ■ treating it with aldehydes. , ■ Painting with a mixture of chlorinated polypropylene and ethylenecyamine, ■ Treating with iodized isocyanate, ■ Oxidizing the surface with ozone treatment, ■ Treating with alkyl hypohalite, [Phase] Modified with polymerized fatty acids. epoxy resin,
Examples include treatment with an amine curing agent and an organic solvent. However, these methods (a) tend to cause unevenness in the degree of surface treatment, (b) have problems with the working environment due to the generation of dust, (c) cause deterioration of the vulcanizate, and (d)
In addition to problems such as requiring special processing agents, (e) complicated processing steps, and (f) expensive equipment,
Even with such treatment, the adhesion of the paint to the base material was not necessarily sufficient.

In addition, a base material consisting of an OH-terminated prepolymer obtained by reacting polyhydroxypolybutadiene hydrogenated to 98% or more with a polyol and a polyisocyanate and a 98%
There is also a description of a coating composition containing as a curing agent an NCO-terminated prepolymer obtained by reacting polyhydroxypolybutadiene and/or polyol with polyisocyanate that has been hydrogenated at least 8715) However, the adhesion of the paint to the base material cannot necessarily be said to be sufficient.

[Means to solve the problem]

In order to solve the above problems, the present inventors have developed products made of various plastics or various rubbers, particularly ethylene-propylene vulcanized rubber and olefin vulcanized rubber materials, and polypropylene containing these rubbers. As a result of extensive research into paint compositions that can be applied to various products made of resin, we have developed a coating composition that can be applied to the surfaces of these rubber materials without impairing their flexibility and flexibility, while also providing sufficient adhesion to the surface of these materials. The present inventors have discovered a coating composition having the following properties, and have accomplished the present invention.

That is, the present invention provides a base material consisting of a urethane prepolymer having ○Hi at both ends obtained by reacting a high molecular weight polyol and an organic diisocyanate, and -NCO at both ends obtained by reacting a high molecular weight polyol and an organic diisocyanate. In a coating composition formed by blending a curing agent made of a urethane prepolymer having a group, 100 to 50 mol% of the high molecular weight polyol is a polyester polyol containing a condensate of neopentyl glycol and a dibasic acid. The present invention provides a polyurethane coating composition characterized by:

The present invention will be explained in detail below.

Examples of dibasic acids suitable for obtaining the polyester polyol containing a condensate of neopentyl glycol and dibasic acid used in the present invention include adipic acid, phthalic anhydride, isophthalic acid, terephthalic acid, maleic acid, Examples include dibasic acids such as fumaric acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, azelaic acid, and sebacic acid, or acid anhydrides corresponding to these acids.

Examples of such polyester polyols include:
Manufactured by Dainippon Ink ■, product name: OD
etc.

The high molecular weight polyol other than the polyester polyol containing the condensate of neopentyl glycol and dibasic acid used in the present invention has an average molecular weight of 500 to 10,0
00. It is preferably 1,000 to 3,000, and one or more of polyether polyols, polyester polyols, polycarbonate polyols, polyether carbonate polyols, polybutadiene polyols, and polycaprolactone polyols commonly used for polyurethane soles are used. I can do it. Among these, polycarbonate polyols and polyether carbonate polyols are preferred. The proportion of the neopentyl glycol-containing polyester polyol in the high molecular weight polyol is 50 mol% or more, preferably 7
It is 5 mol% or more. If this usage ratio is less than 50 mol%, sufficient adhesion cannot be obtained.

The organic diisocyanate used in the present invention includes 2
．． 4-) Lylene diisocyanate, 2,6-lylene diisocyanate, diphenylmethane 4゜4'-diisocyanate, naphthalene-1,5-diisocyanate, 3
, 3'-dimethyl 4,4'-biphenylene diisocyanate and other aromatic diisocyanates; xylylene diisocyanate and other aromatic alicyclic diisocyanates; 4+4'
- Methylene biscyclohexyl diisocyanate (hydrogenated MDI), hexamethylene diisocyanate (MDI)
), isophorone diisocyanate (IPDI), cyclohexane diisocyanate (hydrogenated XDI), and other aliphatic diisocyanates.

In the urethane coating composition of the present invention, the ratio of the equivalent weight (a) of the high molecular weight polyol to the equivalent weight (b) of the organic diisocyanate is set to Use so that ≧(b'). Furthermore, in order for the urethane prepolymer used as a curing agent to have -NCO groups at both ends, as described above, the ratio of the equivalent weight (a) of the high molecular weight polyol to the equivalent weight (b) of the organic diisocyanate is (b)≧ Use it as shown in (a).

As a method for producing the urethane prepolymer of the present invention, a urethanization reaction technique known in the polyurethane industry is used. For example, by reacting a high molecular weight polyol and an organic diisocyanate at room temperature to 200'C, a prepolymer with NCO terminals or OH terminals can be obtained. In these reactions, it is of course possible to use an appropriate amount of a polymerization catalyst known in the urethanization reaction, such as a tertiary amine or an organic metal salt of tin or titanium, if necessary. For example, it is also possible to use various polymerization catalysts described in "Polyurethane Technology" by Keiji Iwata, published by Nikkan Kogyo Shimbun, pp. 23-32. In addition, these reactions may be carried out using a solvent, and preferred solvents include aromatic solvents such as toluene and xylene, which are commonly used as solvents for paints; ester solvents such as ethyl acetate and butyl acetate; Examples include ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; and amide solvents such as dimethylfluoride and dimethyl acetamide. These solvents may be used alone or in combination.

In addition, the blended product of the urethane prepolymer having OH groups at both ends and the urethane prepolymer having NCO groups at both ends used in the present invention can be used in ethylene-propylene vulcanized rubber and olefin vulcanized rubber materials. It can also be used as a primer for paints or as a primer for adhesives applied to various products made of polypropylene resins containing these rubbers.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in detail with reference to Examples, but the present invention is not limited to these Examples in any way.

Note that all parts and percentages used in the examples are based on weight unless otherwise specified.

Incidentally, the ethylene-propylene comb additive BL (r) used in the examples was composed of 100 parts of ethylene-propylene terpolymer, 70 parts of carbon black, and 35 parts of FL extracted oil.
A rubber compound containing 7 parts zinc white, 2 parts stearic acid, 2 parts vulcanization accelerator, and 1.5 parts sulfur is vulcanized at 160"C for 30 minutes, and is an ethylene-propylene terpolymer vulcanizate. (II) contains 100 parts of ethylene-propylene terpolymer, 30 parts of polyhydroxybutadiene, 70 parts of carbon black, 35 parts of extracted oil, 7 parts of zinc white, 2 parts of stearic acid, 2 parts of vulcanization accelerator, and sulfur. 1.5 parts of a rubber compound was vulcanized at 160°C for 30 minutes.

Copolycarbonate polyol reactor equipped with stirrer, thermometer and fractionation tube 1.6-
472 parts (4.0 mol) of hexanediol and 1,
416 parts (4.0 mol) of 5-bentanediol were added, and 1.84 parts (0.0 mol) of metallic sodium was added at 70-80°C.
8 mol) was added under stirring. After the sodium had completely reacted, the temperature of the reactor, into which 472 parts (8.0 mol) of diethyl carbonate had been introduced, was raised to 95-100°C, and ethanol began to distill out. The temperature was gradually increased to 160°C in about 6 hours. During this time, ethanol containing about 10% diethyl carbonate was distilled out. Thereafter, the pressure in the reactor was further reduced to 1 m+h or less, and the reaction was carried out at 200°C for 4 hours with strong stirring. After cooling, the produced polymer was dissolved in dichloromethane, neutralized with dilute acid, and washed with water several times. After repeated dehydration with anhydrous sodium sulfate, the solvent was distilled off, and the temperature was further increased to 2 to 3 mmHg.
Dry at 140'C for several hours.

The molecular weight of the obtained aliphatic copolycarbonate polyol was 2,000.

Example 1 Polyester polyol containing a condensate of neopentyl glycol and dibasic acid (manufactured by Dainippon Ink ■, trade name:
OD X-2044, average molecular weight 2.000) 100
part, hexamethylene diisocyanate (HD I >
5.6 parts, dimethylacedeamide (DMAC) 246.
4 parts and 0.002 parts of diptyltin dilaurate were mixed and reacted at 100°C for 3 hours to obtain an -OH-terminated prepolymer. In addition, for use as a curing agent, polyester polyol containing a condensate of neopentyl glycol and dibasic acid (manufactured by Dainippon Ink ■, product name: O
Mix 100 parts of D I got it. A coating composition was prepared by adding 10 parts of carbon black to 100 parts of the OH-terminated prepolymer and 100 parts of the NCO-terminated prepolymer described above. This coating composition was applied to ethylene-propylene rubber vulcanizate (1), dried at 100°C for 20 minutes,
After curing, a cross-cut peeling test was performed using Nichiban cello tape (12 widths).

The results are shown in Table 1.

Example 2 75 parts of the same neopentyl glycol-containing polyol as in Example 1, 25 parts of the aliphatic copolycarbonate polyol synthesized in the above synthesis example, 6.72 parts of HDI, DMAC
246.4 parts, dibutyltin dilaure) 0.002
were reacted in the same manner as in Example 1 to obtain an OH-terminated prepolymer. In addition, for use as a curing agent, Example 1
75 parts of the same neopentyl glycol-containing polyol, 25 parts of the aliphatic copolycarbonate polyol synthesized in the above synthesis example, 8.9 parts of MDI, DMAC254,
1 part and 0.002 parts of dibutyltin dilauret were reacted in the same manner as in Example 1 to obtain an NCO-terminated prepolymer.

As in Example 1, 100 parts of OH-terminated prepolymer and NC
A coating composition was prepared by adding 10 parts of carbon black to 100 parts of the O-terminated prepolymer.

This coating composition is coated with an ethylene-propylene rubber vulcanizate (
1) and subjected to a gono-meat peel test in the same manner as in Example 1. The results are shown in Table 1.

Example 3 An OH-terminated prepolymer and an NC◯-terminated prepolymer were synthesized in the same manner as in Example 2, except that the amounts of polyol and diisocyanate used were changed to the ratios shown in Table 1. As in Example 2, 100 parts of OH-terminated prepolymer and NC
A coating composition was prepared by adding 10 parts of carbon black to 100 parts of the O-terminated prepolymer. This coating composition was applied to ethylene-propylene terpolymer vulcanizate (II), and a cross-cut peeling test was conducted in the same manner as in Example 2.

The results are shown in Table 1.

Example 4 O
A coating composition prepared by combining an H-terminated prepolymer and an NCO-terminated prepolymer and using these prepolymers in the same manner as in Example 3 was used.
Adhesion to the terpolymer-added 6ff product (Il) was evaluated. The results are shown in Table 1.

Comparative Example 1 As shown in Table 1, OH-terminated prepolymer, NC○
The terminal prepolymers were combined, and the adhesion to the ethylene-propylene rubber vulcanizate (I) was evaluated using a coating composition prepared using these prepolymers. The results are shown in Table 1.

Comparative Example 2 As shown in Table 1, OH-terminated prepolymer and NCO
The terminal prepolymers were combined, and the adhesion to the ethylene-propylene rubber vulcanizate (1) was evaluated using a coating composition prepared using these prepolymers. The results are shown in Table 1.

Comparative Example 3 As shown in Table 1, OH-terminated prepolymer and NCO
Terminal prepolymers were synthesized, and coating compositions prepared using these prepolymers were used to evaluate adhesion to ethylene-propylene terpolymer vulcanizate (If). The results are shown in Table 1.

Comparative Example 4 As shown in Table 1, OH-terminated prepolymer, NC
By combining O-terminated prepolymers and using coating compositions made using these prepolymers, ethylene-propylene Turbo U? -jJD Adhesion to sulfur (II) was evaluated. The results are shown in Table 1.

The following margins [Effects of the Invention] The coating composition of the present invention is extremely effective when used as a coating for ethylene-propylene vulcanized rubber, olefin thermoplastic rubber, and polypropylene resin to which these rubbers are added. It has excellent adhesive properties.

Claims (1)

[Claims] 1. A main ingredient made of a urethane prepolymer having OH groups at both ends obtained by reacting a high molecular weight polyol and an organic diisocyanate, and -NC at both ends obtained by reacting a high molecular weight polyol and an organic diisocyanate.
In a coating compounded with a curing agent made of a urethane prepolymer having an O group, 10% of the high molecular weight polyol
A urethane coating composition characterized in that 0 to 50 mol% of the polyester polyol contains a condensate of neopentyl glycol and a dibasic acid.