Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2002-01-25
2004-12-28
Niland, Patrick (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C428S423100, C523S200000, C523S207000, C524S589000, C524S290000, C524S839000, C524S840000, C528S044000, C528S049000, C528S074500
Reexamination Certificate
active
06835772
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to fine particles of polyurethane resin, a coating composition containing the fine particles thereof for forming a favorable feel coating film, and an article coated with the coating composition.
(2) Description of the Related Art
Automotive interior parts such as instrument panels are generally coated with a matte coating composition in order to impart a high class feel or a favorable feel to parts. Further, some interior articles are coated with a matte coating composition.
Conventional matte coating compositions contain matting agents such as inorganic fine particles, e.g. silica, diatomaceous earth, alumina, calcium carbonate or the like, fine particles of acrylic resins or the like. Coating films formed of these coating compositions are hard and less elastic as the coating film, and lack “gently soft feel (comfortable feel)”.
A matte coating film containing fine particles of polyurethane resin as a matting agent is elastic but uneven, rough and unsmooth on the surface.
As described above, conventional coating compositions are not satisfactory in gently soft feel (comfortable feel) and remain unsatisfactory in terms of feel.
BRIEF SUMMARY OF THE INVENTION
An object of the invention is to provide a favorable feel coating film having gently soft feel (comfortable feel), and a coating composition for forming such coating film.
It was heretofore considered difficult to quantitatively determine the feel. Recently, however, a concept of “soft value (S value)” for quantitatively determining the feel has been established [Kenji Kawazu et al., Society of Automotive Engineers of Japan, Inc., Proceedings, No.87-99, p.p.19-22 (1999); and Kenji Kawazu et al., SAE Technical Paper Series, 1362 (2000-01)]. The S value is determined based on 4 sensory factors, namely, moist-dry feel, smooth-rough feel, warm-cool feel and soft-hard feel.
We quantitatively determined the feel of coating films containing inorganic fine particles or fine particles of acrylic resin based on the S value. It was found that the surface of the coating film was hardened due to the matting agent and that the coating film lacked the required elasticity of coating film and was markedly insufficient in moist-dry feel and soft-hard feel. On the other hand, coating films containing fine particles of polyurethane resin were found superior in soft-hard feel to coating films containing inorganic fine particles or fine particles of acrylic resin but inferior in moist-dry feel and lacking in “gently soft feel (comfortable feel)”.
The present inventors conducted extensive research to improve the “gently soft feel” by increasing the moist-dry feel and soft-hard feel. In the course of the research, the inventors evaluated the feel of coating films formed of coating compositions containing fine particles of polyurethane resin and lanolin. The coating films were superior in gently soft feel but inferior in resistance to beef tallow, adhesion, recoat adhesion, moisture resistance, and wear resistance.
The present inventors carried out further researches and consequently found the following. When fine particles of lanolin-deposited polyurethane resin obtainable by reacting at least one member selected from the group consisting of polyester resins and polyether resins with polyisocyanate having at least two isocyanate groups in a poor solvent in the presence of a lanolin derivative, it is possible to form a favorable feel coating film which is superior in “gently soft feel” and outstanding in resistance to beef tallow, adhesion, recoat adhesion and the like.
Furthermore, the present inventors investigated improvements of such coating composition in the low-temperature curability and pot life. Generally, curable resin compositions contain a reaction accelerator in an amount of about 0.1 wt. % based on the total weight of solids in the coating composition to enhance the curability, and a reaction retarder in a specified amount based on the conventional amount of the reaction accelerator, i.e. in an amount of about 1 wt. % based on the total weight of solids in the coating composition to extend the pot life. Since the coating composition of the invention failed to achieve the low-temperature curability by conventional measures, the inventors tentatively incorporated a reaction accelerator in more than the conventional amount. In this case, a conventional amount of reaction retarder was used, but failed to give longer pot life. In a further course of the investigation, it was considered that the use of a large amount of a reaction retarder would lower the solubility of the polyisocyanate, so that it would be impossible to obtain a coating composition having a prolonged pot life. Surprisingly, however, when the inventors tentatively added a large amount of a reaction accelerator and a large amount of a reaction retarder, it was discovered that two conflicting effects, i.e. superior low-temperature curability and longer pot life, were attained at the same time.
The present invention was accomplished based on these findings.
The invention provides the following.
Item 1. Fine particles of lanolin-deposited polyurethane resin comprising a lanolin derivative and fine particles of polyurethane resin, the lanolin derivative being not removed (being retained) even when the fine particles of lanolin-deposited polyurethane resin are washed with a good solvent for the lanolin derivative.
Item 2. The fine particles of lanolin-deposited polyurethane resin as defined in Item 1 which have an average particle size of 5 to 40 &mgr;m.
Item 3. The fine particles of lanolin-deposited polyurethane resin as defined in item 1 which are obtainable by reacting at least one member selected from the group consisting of polyester resins and polyether resins with a polyisocyanate having at least two isocyanate groups in a poor solvent in the presence of the lanolin derivative.
Item 4. The fine particles of lanolin-deposited polyurethane resin as defined in item 3, wherein the amount of deposited lanolin is such that the average particle size is increased by 1 to 5 &mgr;m when reacting said at least one member selected from the group consisting of polyester resins and polyether resins with the polyisocyanate having at least two isocyanate groups in a poor solvent in the presence of the lanolin derivative, compared with the average particle size of fine particles obtained by reacting said at least one member selected from the group consisting of polyester resins and polyether resins with the polyisocyanate having at least two isocyanate groups in a poor solvent in the absence of the lanolin derivative.
Item 5. A process for preparing the fine particles of lanolin-deposited polyurethane resin as defined in item 1, the process comprising reacting at least one member selected from the group consisting of polyester resins and polyether resins with a polyisocyanate having at least two isocyanate groups in a poor solvent in the presence of a lanolin derivative.
Item 6. A coating composition comprising:
(i) at least one binder resin selected from the group consisting of polyester resins and polyether resins, the binder resin having a glass transition temperature of −30 to −70° C., a number average molecular weight of 1,000 to 50,000 and a hydroxyl value of 30 to 70 mgKOH/g resin,
(ii) a polyisocyanate having at least two isocyanate groups,
(iii) the fine particles of lanolin-deposited polyurethane resin as defined in item 1, and
(iv) an organic solvent.
Item 7. The coating composition as defined in item 6 which contains 5 to 20 parts by weight of the fine particles of lanolin-deposited polyurethane resin per 100 parts by weight of the total weight of the binder resin and the polyisocyanate having at least two isocyanate groups.
Item 8. The coating composition as defined in item 6 which further contains (v) a reaction accelerator and (vi) a reaction retarder, wherein the amount of the reaction accelerator is 0.2 to 2% by weight based on the total weight of solids in the c
Arimoto Hiroyuki
Kai Mika
Kawazu Kenji
Kishimoto Takayuki
Kita Takashi
Niland Patrick
Ohashi Chemical Industries Ltd.
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