CA1174398A - Polyurethane resins and polyurethane resin coating compositions - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE Polyurethane resins with an excellent weather resistance are provided by the reaction of polyols with trifunctional isocyanates which are expressed by the following general formula: (R = a remnant of divalent hydrocarbon group with the carbon number of 2 or 3) The reaction between a polyol and a trifunctional isocyanate is effectuated at an NCO/OH mole percentage of 0.5 to 2.0 and adjustments are made so that the concentration of carbamide group will be 5 x 10-4 to 50 x 10-4 moles per gram of the reaction product and that the bridging parameter will be 150 to 1,500. The resins may be used to best advantage as polyurethane resin coat-ings excelling in weather resistance.

Description

3~3 Title of the Invention Polyurethane Resins and Polyurethane Resin Coating Compositions BACKGROUND OF THE INVENTION
Field of the Invention The present invention relates to polyurethane resins which are beneficial as material producing a polyurethane resin coat with, in particular, an excellent weather resistance.
Description of the Prior Art Polyurethane resins are classified into two types by the kind of isocyanate compounds contained in them --the "yellowing" and "non-yellowing" types. Isocyanates which have hitherto heen in use as ones giving polyurethane , resins of the non-yellowing type include: such aliphatic isocyanates as hexamethylenediisocyanate, isophoronediisocyan-ate, 2,2,~-trimethylhexamethylenediisocyanate, dicyclohexyl-methanediisocyanate) etc.; and xylilencdiisocyanate, etc.
Whilst non-yellowing type polyurethane resins obtaincd by - 1 - '~

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causing these isocyanates react with polyols have been employ-ed as coating materials, there still remained many problems to be solved in using them for such purpose.
One of the problems is their toxicity. Since isocyanate compounds are substances which are chemically highly reactive, they are very dangerous when used by persons who are of an allèrgic constitution or have weak respir-atory organs. Because of this, the limit of concentration in the atmosphere of, for instance, monomers of toluene-diisocyanate, diphenylmethanediisocyanate, etc., was fixed at 0.02 ppm by the Commission of the American Conference of Governmental Industrial Hygienists. From such reason, for one thing, the aforesaid isocyanate monomers are seldom used as they are in polyurethane coatings, except in special cases, but are generally used after having been modified into prepolymers -- adducts obtained by adding them to tri-methylolpropane, ethylene glycol, etc. This modification has the effect of lowering vapor pressure, thereby reducing toxicity and bad odor, and, in addition, of allowing the ~ ~ t~

adjustment of reactivity to be made and the diversification of the type of coatings to be realized.
Since, however, it is industrially extremely dif-ficult to wholly eliminate isocyanate monomers in the prepolymer additions, the Eact is still that one smells a strong irritating odor while he is engaged in the work of pre-paring coating materials or of applying coats, many people complaining of the symptoms of respiratory diseases peculiarly contracted by inhaling isocyanate vapor, and with an increase in the use of polyurethane products, this question has been brought much to the fore.
With the isocyanate additions, in particular, it is said that there occurs dissociation of diisocyanates --highly toxic monomers -- while they are in store, depend-ing upon the storage conditions, and this constitutes an uneasy factor for those concerned -- chemical engineers and operators. Under such circumstances, measures are being taken for improvement of the working environment, for instance, ensuring a good ventilation, so that the . \ - 3 -~ ` ~ f~3~

operator~ will not directly inhale ~apor of isocyanate compounds. However, the state o~ things in this connec-tion is ~till far from being satisfactory.
The second question in the conventional technology is that there remain~, with the conventional coatlng~, much to be desired in respect of their weather resi~tance.
Although the non-yellowing type polyurethane re~ins were orlginally developed with a view to improving the weath-er resistance o~ coatings~ they are not, as yet, euffi-ciantly resistant to weather when used as coating for application to those commoditie~ which are exposed to severe conditions outdoor over a long period of time, uch as automobile~, railroad carriages, aircrafts, ve3-~els, building materials, and 80 forth.
- The third question concerning polyurathane coating $
materiQls according to the conYentional technique3 i5 .~j that the rQnge in which the selection of solvent compo- -~
sition can be made is not nece~arily ~ide enough, and that, if the amount of ~olvent is reduced from the view-point o~ energy saving and preventi~n of environmental " , - 4 ~
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pollution, the resultant product being the so-called "high solid type" coating with a high concentration of polyure-thane resin~ the coating work efficiency is much impaire~
because of its high viscosity.
SUMMARY OF TIIE INVENTION
The main object of the present invention is to pro-vide polyurethane resins and polyurethane resin coatings hav-ing a high resistance to weather.
Another object of this invention is to provide poly-urethane resin coating compounds affording an improved coating work efficiency.
Still other objects of the present invention will become clear from the description to follow.
A polyurethane resin film coat with an excellent weather resistance is provided by the present invention. This film coat has for its main ingredient a polyurethane resin which is a reaction product obtained by causing (A) a polyol to react with (B) a trifunctional isocyanate expressed by the following general formula:

OCN - (CH2)4 - CH - NCO
C = O
O - R - NCO
(R = a rcmnant of divalent hydrocarbon group with the carbon numbcr of 2 or 3) at an NCO/OII mole percentage of 0.5 to 2.0, and of which the concentration of carbamide group is 5 x lO 4 to 50 x 10 4 moles per grams of said reaction product, and the bridging parameter 150 to 1,500.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A polyol as referred to in the present invention means a compound or polymer containing two or more hydroxyl groups per molecule.
As examples of polyols, there are diols, triols, tetraols, pentols and hexitols; while there are also such polymer polyols as polyester containing two or more hy-droxyl radicals per molecule (hereinafter called "poly-ester polyol"), polyether containing two or more hydroxyl groups per molecule (hereinafter called "polyether ~ r ` 1~ 7~91~

polyol"), acrylic polymer conta~ning two or more hydrox-yl radicals per molecule (hereinafter called "polyacryl polyol"), etc. In the present invention, the~e may be used either slngly or as a mixture of two or more kinds.
Hereunder are given further example~, in more particulars, o~ polyols.
Diol8:
ethylene glycol, propylene glycol, ~ ~dihydroxy- .
- diethyl ether (diethylene glycol), dipropylene glycol, 1,4-butylene glycol, 1,3-butylene glycol, polyethylene glycol, polypropylene glycol, poly- ~.
propylene-polyethylene glycol, polybutylene gly-. col;
. ~riols:
glycerine, trimethylol propane, 1,2,6-hexanetriol; -Tetraols~
penta erythritol, 2-methylgluco~ide;
Hexitol: '`!'3, sorbitol;
Polyester polyol~
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These are polymerized by the eonden~ation reac-tion between a polybasio acid, such a~ adipie acid, dimer acid, phthalic anhydride, isophthalie acid, etc., and Q diol or triol, such a~ ethylene gly-col, diethylene glycol, propylene glycol, trimeth-ylol propane, glyeerine, ete.
Polyether polyols:
These are prepared by adding propylene oxide, ethylene oxide, or the like, to a polyhydrie al-eohol, such as glyeerine, propylene glycol, etc.
- In thi~ eategory are also included polyether polyols rieh in hydroxyl radicals obtalned by ~ eau~ng a multi~unetional eompound ~uch a~ ethy- , - lenediamine, ethanolamine, etc. to reaet with - ethylene oxide or propylene oxide. ~.
Polyàcryl polyols:
Copolymer~ of an aerylie aeid ester or metha~
crylic acid e~ter containing a hydroxyl group ex-pre~sed by the following general formula~
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H2C = C ~ O - R2 - (OH)n o wherein . n = 1, 2 or 3 Rl = hydrogen or methyl R2 = a remnant radical of ~ub~t~tuent or non~ub~tituent hydrocarbon ~ith the carbon number of 2 to 12 . and a monomer which is capable of being copoly-merized with ~uc~.
Hereunder are enumerated examples o~.acrylic ac-id esters or methacrylic a¢id esters ¢ontaining the aforesaid hydroxyl group.
. . 2-hydroxyethyl acrylate; 2-hydroxypropyl aoryl~
. ate, 2-hydroxybutyl acrylate, 2-hydroxyethyl :.
. methacrylate, 2-hydroxypropyl methscrylate, ~
3-hydroxypropyl methacrylate, 4-hydroxybutyl ~f . metha¢rylate, 2-hydroxypentyl methacrylate, methacrylic acid monoester of glycerine, ac-, ' ;~
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rylic acid or methacrylic acid monoester o~
trimethylol propane, 2-hydroxy-3-chloropropyl acrylate, 2-hydroxy-3-chloropropyl methacryl-ate, etc.
Out of these, the most desirable are: 2-hydroxy-ethyl methacrylate, 2-hydroxyethyl acrylate and

2-hydroxypropyl methacrylate.
In the next place, example~ of monomer~ which are capable of being copolymerlzed with the above-mentloned acrylic acid or methacrylic esters con-taining a hydroxgl group are given below. t - (1) acrylic acid or its esters, for example, acrylates of methyl, ethyl, propyl, butyl ,., or 2-ethylhexyl `

- (23 methacrylic aoid or its esters, for exam-ple, methacrylates of msthyl, ethyl, buty~, decyl, 2-ethylhexyl or lauryl

(3) styrene or its derivatives, for example, -i~
~-methylstyrene, ~-chlorostyrene, etc.

(4) vinyl ester~, for example, vinyl aoetate, :~
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1~74;~3~3 vinyl propionate, vinyl isopropionate, etc.

(5) nitriles, for example, acrylonitrile, methacrylonitrile, etc.
Out of these, the most de~irable are: methyl acrulate, ethyl acrylate, butyl acrylate, methyl methacrylate, butyl methacrylate, lauryl metha-crylate, acrylic acid, methacrylic acid, styrene, acrylamide, vinyl acetate, etc. I
~o prepare polyacryl polyols be,-~-t ~uited for the purpose, it i~ de~irable that the amount of each monomer used be ~elected from the following range~. ;' (A) Hydroxyalkyl(meth)acrylate ....................... ~
... 5 to 30 pct; by wt. ~, (B) Alkyl ester of acrylic acid and/or ,~
of methacrylic acid ............................. 50 to 9S pct. by wt. ;~(C) Other rnonomer(s), a~ occasion demands ........... '~, ... O to 50 pct. by wt. ~', (D) Acrylic acid or methacrylic acid ...
... O to 10 pct. by wt. , If, of the foregoing, the amount of hydroxyalkYl ~ ~,,''~"
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(m~th)acrylate is less than 5 pct. by wt~, the de-gree of bridging by reaction with isocyanate com-pounds becomes too small and hence it will be im-possible to obtain a film coat with ~uch perform-ance as wa~ expected.
While the manufacture of polyacryl polyol~ by copolymerization o~ monomers, as de~cribed above, may be carried out by any one of such known meth-od~ of polymerization a~ 301ution, block, emulsion and su~pension polymer~zation, the fir~t mentioned method, i.e., solution polymerization i9 generally employed. ~ ;~
Selection of polyols may be made at one 1 8 di~cretion . :'.'".
80 as to fit the purpose; but, ln general, the use of polyester polyols or polyacryl polyols i~ preferable. `~
~ A~ for the molecular weight of polyol~ used, too, se~
lection may be made from quite a wide range according to ~
the purpose. For the "high solid type" coating, howe~er, ~J, a range of 500 to 5,000, especially, 500 to 3,000, is ;~
preferred. More particularly, when polyester polyols ."~ `

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_ _ are used, those with a molecular weight in the range o~
500 to 1,000 are be~t suited for the purpo~e; while when polyacryl polyols are used, those with a molecular weight in the range of 1,000 to 3,000 may be utilized to be~t advantage. When manufacturing coatings which are not o~
the "high solid type~, polyols with a molecular weight higher than ordinary are employed.
The trifunctional isocyanate compounds employed in the present invention are those expre~sed by the general for-mula previously given in this ~pecification, of which typical examples inolude: ,, , 2, 6-diisocyanate caproic acid -~-isocyanate ethyl ~', ' ester; 2, 6-diisocyanate caprolc acid -r-isocyanate .~:
' propyl ester; 2, 6-diisocyanate caproic acid -2-meth~
yl-~-isocyanate,ethyl e~ter; ebo. ~ ~;
All these can be manufactured by causing an e~ter of ly- ~~
sine ànd aminoalcohol~ to react with phosgene.' - Here, it i~ difficult to achieve polymeriæation if, ,''''1, in the aforesaid general formula, the carbon number of R
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is 1; while if the carbon number i~ 4 and over, the con~
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tent of isocyanate in the trifunctional isocyanates be-comes too small, and this will be detrimental to the phys-ical properties of polyurethane resin film obtained by the reaction with polyols, and will, besides, make the viscosity of the trifunctional isocyanate compounds high-er, thus making the product unsuitable for the purpose of this invention.
By making a proper choice of polyols to be used and by adjusting the NCO/OH mole percentage, the physical properties and hence efficiency of the product, such as the strength of film cost, flexibility, chemical resistance, solvent resistance, etc., can be modified in a wide range, thereby to make it suitable for specific purposes.
Compounds of which the NCO/OH mole percentage is in the range of 0.~ to 2.0 are suited for the manufacture of films and for the application of film coat. For poly-urethane coatings, in particular, the range of 0.5 to 1.2 ; is preferred.
If the NCO/OII mole percentage is below the lowest figure, as above, hot water and acid resistance oE the film - 1~ -`
` ~4~'3~3 coat produced i~ lowered, resulting in a poorer weather re3i~tance. When it i~ abo~e the highe~t figure, too, there takea place a lowering of weather resistance.
Those with an NCO/OH mole percentage in the range of 0.5 to 1.0 may be used to advantage for ~uch ~ield~ as electrical in~ulation, cap~ulation, and manufacture of cast products~
When the NCO/OH mole percent~ge is in the range of 0.1 to 0.7, such compound~ may be advantageously utilized for the manufacture o~ highly ef~icient adhe~ives or hard-ening agents. When, on the other hand, the NCO/OH mole percentage i8 greater, ~uch compounds are suited for the manufacture of foam product~. ~he foaming may be achieved ` by introducing a carta1n fixed amount of water or a blo~-lng agent into the rsaction products, by utilization of the known techniques of foaming.
It is ne¢es~ary that the ooncentration of the carbam~
ide contained in the product of reaction between a poly-. . . . -, ol and a trifunctional isocyanate be in the range of 5 x ~'i 10-4 to 50 x 10-4 moles per gram of ~aid reaction pro- ;~
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duct. The term "carbamide radical" Q5 herein used indi-cates a group expressed by thi~: - NH - ~ - , which ex-i~ts in the urea bond, urethane bond, biuret bond and allophanate bond. In an IR analysis, the existence o~
this carbamide radical can be confirmed from a peak some-where around 1530 cm~l. If the concentration of the carbamide radical is lower than the above, it i~ impos-sible to obtain a film coat which excels in durability, pliability, ~olvent and chemical resi~tance, adhesive power, etc. If, on the other hand, the concentration iB
hi~her than the abo~e, a film ~oat produced will have a poorer weather resistance.
It is necessary that the bridging parameter E (cal- ;~
culated value) of the afore~aid reaction produets be in the range of 150 to i,500. If it is lower than thi~ low-er limit, the pliability o~ a film ooat obtained will be i~
very poor. If, on the other hand, it i8 hlgher than the ~
upper limit, a film coat with a good durability cannot ~i be obtained. Her~, the bridging parameter Ec indicate3 ' a parameter so defined by T.C. Patton (Of~. Dige~t, 34 ~
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446, 348 '62), as hereunder given, viz.:

Wl + W2 C
WlCl W2C2 FlEl F2E2 wherein Wl = weight of polyol;
W2= weight of isocyanate;
Fl= degree of functioning of polyol;
. F2= degree of functioning of isocyanate;
.- Cl= degree of bridging function of polyol, Cl = Fl - 2;

C2= degree of bridging function of isocyanate, . C2 = F2 ~ 2;
El= equivalent weight of polyol; and , E2= equivalent weight of isocyanate.
The polyurethane resin coating of the present invention is adap~able to both the one-component and two-component types, but it is more advantageous to use it as the two-component type coating.
(1) Two-Component, Po]yol ~lardening Type ., This is a two-component type polyurethane resin coating constituted of a kneaded mixture of a polyol and a pig ment, the latter being added at need ("A" liquid) and a tri-functional isocyanate of the present invention, diluted with a solvent as needs be ("B" liquid). At use, "A" and "B" liquids are mixed together and, when necessary, the viscosity is ad-justed by the use of a thinner. For mixing the two liquids, a two-liquid gun may preferably be employed. It is desirable that the mixing ratio be determined in such a manner that the NCO/OH mole percent will be 0.5 to 2.0, concentration of carb-amide radical 5 x 10 4 to 50 x 10 4 moles per gram of the reaction product, and bridging parameter 150 to 1,500.
The solvent of "B" liquid and the thinner of the ; mixture, which are used at need, may be either the same or different; but, in the latter case, it is necessary that the two are compatible with each other. Further, these must not be ones which are reactive with isocyanates and polyols, such as ones containing active hydrogen atoms. Some examples of solvents that may be used are given below.

Hydrocarbon solvents:
benzene, toluene, xylene, and aromatic naphtha.
E~ter ~olvent~:
ethyl acetate, butyl acetate, cello~olve, hexyl acetate, am~l acetate, ethyl propionate, and butyl propionate.
Ketone solvents:
acetone, methyl ethyl ketone, methyl isopropyl ketona~ methyl isobutyl ketone, diethyl ketone, and cyclohexanone.
- Glycol e~ter sol~ents:
ethylene glycol monoethyl ether acetate, and ; diethylene glycol monoethyl ether acetate. -One of the characteri~tics of the present invention lies in that, of the whole compo~ition of solvent, more than 50 pct. by wt. can be the aforesaid hydrocarbon 901-vent. ~
, . :`-1 Further, the arnount of solvent in the aforesaid "B"
liquid can be as small as O to 50 pct. by wt., and this al~o con~titutes a characteristic of the coating in ac-,~ . , ~.
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cordance with the pre~ent invention. This m~kes it eas-ier to obtain a "high solld type" coating - a contribut-ing factor to an improvement of the outward appearance of film coats.
~ 8 for polyol~ to be used, those which were previous-ly mentioned, that i8, polyester polyols, polyether poly-ols, polyacryl polyols, etc., are recommended. These are certain to give good results.
By combinlng proper kinds of polyols and isocyanate COmpOUnd8 ~ it i8 possible to obtain c02ts of ~aried pro-pertie~, from soft to hard and tough ones, all of which being possessed of an excellent resistance to weather, ~-water, chemical~ and sta1n. Coatings of this type are ~.
ordinarily u~ed at temperature~ ranging from room tem- '`é
perature to 120C. ~hey display an excellent adhesive . -~
property when used for coating of suoh materials as fer-rous and nonferrou~ metals, plastics, rubber, leather, concrete, etc., and hence have a wide range of applica-tions in such fields of industrles as manufacture of building materials, automobile~, machineB and lnstruments, : . - , - 20 - ~t ., `~
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and woodworks; building of aircrafts, railroad carriages and ships; and so forth.
(~) One-Component, ~leat Curing Type With coatings of the two-component, polyol harden-ing type which has been described in the foregoing, the reaction progresses e~en at room temperature; hence there frequently arise cases where the pot life of coatings in use presents a problem.
In this type of coating, one-liquid, heat curing type, the isocyanate group of isocyanate compounds is once blocked by the addition of a blocking agent so that the coating will be stable at room temperature. The coating, after having been applied, is heated to dissociate the blocking agent. The isocyanate group is thus activated again and is caused to react with the hydroxyl group to form a film coat. This method is best suited for such applications as coating of automobiles on a manufactur-ing line, or the like, where it is necessary to ensure stability of coating materials while they are in store at room temperature.

,~r As polyols to be combined with the blocked type i90-cyanate prepolymer, polyester polyols and polyacryl poly-019 may be used to best advantage.
As blocking agents for the purpose of masking free isocyanate radical of the trifunctional isocyanate com-pounds u~ed in the present invention, tho3e which are in general use may be brought into employment. Hereunder are given some examples of ~uch blockin~ agents.
Phenol, m-nitrophenol, p-chlorophenol, catechol, ethyl malonat~, acetylacetone, ethyl acetoacetate, ; cre~ol; ~-caprolactam, methyl ethyl ketoxime, cy-clohexanoneoxime, butyl mercaptan, methanol, eth-; anol, ethylene chlorohydrin, etc.
Although the temperature at which the above-mentioned blocking agents are dissociated varies with the kind of ~ ;~
such agent3, it is generally accepted that heating to at least 120C is required. Since the coating of this type thus require~ baking at a relati~ely high tempera- ~
ture, it has hitherto been in use mainly in 3uch fields If as the manufacture of electric wires, etc. It i~ ex-. ~ , . . ,, . ,~

pected, however, that there will be new developments in its utilization, such as adaptation to a powder paint with polyurethane resin base, to an aqueous emulsion paint, and so forth.
Solvents for this type of coating, which are used as occasion demands, are identical with those in the '~ case of the two-component type coatings. In this instance, too, more than 50 pct. by wt. of the whole composition of solvents can be hydrocarbon solvents.
The coating compounds according to the present invention can be applied to articles to be coated in an ordinary method of coating, such as spray, brush or roller coating or dipping. It also permits the use of common-ly used pigments and plasticizer, or other kind of ad-ditives which are used in small amounts when preparing the paint or when applying it, provided that the amount used is within the limit of the common practice. For the choice of pigments, it is necessary to pay attention to their water content, as well as to their properties like in the case of selecting solvents. It is to be not-;~

ed that extenders, in particular, have a great water ad-sorbability.
Catalysts may also be used to quicken drying and hardening. For instance, such tertiary amines as di-methylethanolamine, triethylenediamine, etc., and such organic salts of tin as stannous, dibutyl tin dilaurate, etc., may be employed.
The characteristics of the coating according to this invention are as follows:
(1) It excels in gloss retention and anti-cracking properties.
~ 2) It has an excellent resistance to acid and water.
It is thought that, besides this comes from the fact that it hardens very quickly after application, such property is closely related to the network-like structure of the coat produced by hardening with the trifunctional iso-cyanate compound used in the present invention.
(3) It facilitates an improvement in the out-ward appearance of the coat.

~ - 24 -: ` ~7~3~l~

:
., Whilst the luster and build of a coat are related to various ~actors, the influence of the coating on the under coat i~ a factor which must not be left un-heeded. With the compounds of this invention, it is possible to use a variety of solvent~ and, in partic-; ular, much of aromati¢ compound solvents. ~his per-mits lessening the influence of the coating on the under coat, for instance, primer ~urfacer; that i9, the permeation of the solvent-i~ kept to the minimum, helping to achieve an improvement in the outward ap-pearance of the coat. Thu~, it i8 best ~uited for such purposes a~ coating of automobiles, etc., ~here an empha~is 18 placed on a good outward appearance.
(4) It contribute~ to development of coatings of the q "high solid type".
Amidst the recent moves for restriction on environ-mental pollution, the de~elopment of polyurethane resin coatings of the "high solid type" or of the solventless type are is attracting much attention of the circles concerned. Isocyanate as an ingredlent . ' ' 1~
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of such coatings i8 required to have, like the polyol ingredient, a low viscosity at room temperature. As th~ trifunctional i~ocyanate u~ed in the pre~ant in-vention has a low molacular weight, it has a low vis-cosity, hence may be ~ntended for the manufacture of coatings that will help to pre~ent environment~l pol lution. It is also pos~ible, by proper ¢hoice of polyol~, to manufacture solYentle~ coatin~ and thus to contribute to sa~ings in resources or energy.
The coating of the present in~ention ~g, because o~ its low vi~cosity, excellent in respect of coating work efficien~y, too.
(5) Hardening ~pead i8 graat.
Although the hardening ~peed at room temperature . ., is not ~o clearly dif~erent ~rom that of ooating ma-terials on the market, it becomes conslderably great~
. ;,~
er than the latter with the ri~e of baking tempera~
ture. Thu~, lt i~ po~sible to shorten the time re-quired for curing.

(6) Low toxicity.
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1~ L398 Hexamethylenedii~ocyanate prepolymer~ or adduct~
have, in general, a pretty ~trong irritating o*or.
Thi~ is becau~e, it i8 ~aid, of the exi~tence of a very ~mall amount of hexamethylenediisocyanate mon-omer~ in the prepolymers or adduct~. With, on the other hand, the trifunctional isocyanate compound~
employed in tha present invention, the vapor pre~-eure i~ remarkably low, and there ie, while they are belng kept in store, no liberation of volatile in-gredients with high toxicity. A1BO~ their NC0 con-tent i8 higher than that o~ costing materiale on the market. Therefore, the coating of thi~ invention emits little irritating odor which iB peculiar to the isocyanate content of coating3. As, be3ide~, the _ proportion of thé ieocyanate ingredient to that of the polyol lngredient may, in view o~ ite high NC0 content, be reduced, it iB quite advantageou~ from the viewpoint of hygene.
The polyurethane resin of the pre~ent invention may be put to, be~ide0 the uee ae ooating material as above, ~ 'l i . ~ ?'.
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- 27 - ~

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1~7~3'i't3 a wide range of uses in various fields of industries.
For instance, those with an NCO/OH mole percentage in the range of o.5 to 1.0 may be used to adva~tage for ~uch fields as ~lectrical in~ulation, capsulation, and manu-facture o~ cast product~.
When the NCO/OH mole percentage is in the range o~
O.l to 0.7, such compounds may be advantageou~ly utilized for the manufacture of highly efficient adhesives or hard-ening agents. When, on the other hand, the NCO/OH mole percentage i~i greater, ~uch compou~dY are ~u~ted for the manufacture-of foam products. The foaming may be achieved by introducing a certain fixed amount of water or a blow-ing agent into the reaction products, by utilization of the known techniques o~ foaming.
. In the ~ollowing, the present invention ~ill be ex~
plained in concrete -terms by olting several examples of IQ
it~ embodiment and comparing them with a few examples of cases where the method o~ preparation is not quite the same. "Part or part~", of the compositions shown in the examples, mean~ "part or parts by weight". ~j . : ~ "
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- 28 - - `
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.

~:~ 7~3~3 olymerization of 2,6-diisocyanate caproic acid -~-isocyanate ethyl ester as a tri-functional isocyanate compound>
122.2 g (2.0 moles) of ethanolamine, 100 ml of o-dichlorobenzene and 420 ml of toluene were put in a four-mouthed flask fitted with a stirrer, a thermometer, a gas-introducing tube and a reflux condenser combincd with a Dean-Stark apparatus; and by introducing into it hydro-gen chloride gas under ice cooling, ethanolamine was con-verted into hydrochloride. Subsequently, 182.5 g (1.0 mole) of lysine.monohydrochloride was added; by heating the mixture to a reaction temperature of 80C, hydrochloride of ethanolamine was caused to melt; and then by introducing into it hydrogen chloride gas, it was converted into lysine.dihydrochloride. It was continued to pass hydrogen chloride gas through the compound at a rate of 20 to 30 ml per min., with the reacting mixture heated to the reflux temperature (116C), and such temperature was maintained until there no longer was distillation of water. The reaction was let to con-tinue for approximately 9 hours; thereafter, the solvent was decanted, and to the resultant oil-like substance was added a mixture of methanol and ethanol and a heat was applied. When such product was let to stand at room tem-perature, there was a decomposition of crystals. By filter-ing out these crystals, 165 g of tertiary hydrochloride of lysine-~-aminoethyl ester having a melting point of 175C, recrystallized from the mixture of methanol and ethanol, was obtained.
This trihydrochloride was pulverized and was then vacuum-desiccated at 50C for 8 hours. Subsequent-ly, it was put in a four-mouthed flask provided with a stirrer, a thermometer, a gas-introducing tube and a reflux condenser, and by pouring 2.1 lit. of o-dichloro-benzene into it, it was made into a suspension. While stirring this suspension, phosgen was passed through it at a rate of 2.8 moles/hr., and the suspension was heat-ed at 120C for 10 hours. When the temperature was grad-ually raised to 150C over a space of time of 6 hours, the suspenoid was practically wholly dissolved into the ~ - 30 -1~7~

liquid. Af-ter eooling, the liquid was *iltered and the solvent was eliminated by di~tillation under reduced pres-~ure. The residue was distilled under nitrogen gas flow u~ing an oil dif~u~ion pump. The produet: 140 g (yield 90%) o~ lysine i~oeyanate ~-isocyanate ethyl ~ster (2, 6-dii~ocyanate eaproic acid ~ ocyanate ethyl e3ter) ( hereinafter to be called "LTI-E" for ~hort) with a boiling point of 155 to 157C/0.022mmHg, a eolorle~s, tran~parent liquid. Vi~cosity: 29 eps/20C. NC0 con-tent: 47.1 ~ by wt. (ealeulated value 47.2~ by ~t.).
Infrared spectrum: 2225 (i~oeyanate group), 1745em-(e~ter earbonyl), 1460, 1355, 1200cm~l~ester ether~.
Nuclear magnetie re~onanee ~pretrum: 1.2 to 2.3 ppm (6H), 3.2 to 3.95 ppm (4H, - CH2 - NC0), 4~0 to 4.7 ppm `

. ,, NC0 : -(3H, - CH COOCHz - ) Mass ~pectrum: m/c 153 (OCNCH2CH2CH2CH2 - CHHC0), 267 (molecular weight).

< Polymerization of 2, 6~diisocyanate eaproie acid - r-i~ocYanate propyl e~ter a~ a tri-functional isoeyanate compound ~

. .. , ,.,~
- 31 - ~
. ~., , ' 1 . ' ' ~, . . 1!

~ ~;t~ 3 ~ ~

30 g ~0.4 mole) of 3-aminopropanol and 100 ml of toluene were put in a four-mouthed flask fitted with a stir-rer, a thermometer, a gas-introducing tube and a reflux condenser combined with a Dean-Stark apparatus; and by intro-ducing into it hydrogen chloride gas, 3-aminopropanol was converted into a hydrochloride. Then, 36.6 g (0.2 mole) of lysine.monohydrochloride was added, and by introducing into the mixture hydrogen chloride gas again, it was converted into dihydrochloride of lysine. The reacting mixture was heated to the reflux temperature (110C) and, meanwhile, hydrogen chloride gas was passed through it. After the lapse of 11 hours, azeotropic distillation of water stopped. Toluene was eliminated from the resultant product, and ethanol was added to the residual oil-like substance and a heat was applied to the mixture. When such product was let to stand at room temperature, there was a deposition of crystals.
By filtering out these crystals, 47 g of trihydrochloride monohydrate of lysine-y-aminopropyl ester having a melting point of 138 to 145C, recrystallized from a mixture of ;~.
....

methanol and ethanol, was obtained.
In the next place, 25 g of desiccated powder of trihydrochloride monohydrate of lysine-r-aminDpropyl ester, polymerized as above, and 300 ml of o-dichlorobenzene were put in a four-mouthed flask provided with a stirrer, a thermometer, a gas-introducing tube and a reflux condenser so as to form a suspension. Maintaining the temperature of the suspension at 105C, phosgen was passed through it at a rate of 0.4 mole/hr. ~or 10 hours. In the next place, the temperature was gradually raised to 150C, and the reaction was let to progress at such temperature for 4 hours. After cooling, the liquid was filtered and the solvent was eliminated by distillation under reduced pres-usre. The residue was made to undergo a molecular distil-lation. The product: 7.2 g (yield 34%) of lysine di-isocyanate-y-isocyanate propyl ester (2,6-diisocyanate caproic acid -~-isocyanate propyl ester) (hereinafter called "LTI-P" for short) with a boiling point of 153 to 155C/0.03 mmHg, a light yellow liquid. Viscosity: 28 cps/20C.
NC0 content: 44.6% by wt. (cal-culated value 44.8% by wt.) Infrared ~pectrum: 2225cm~l(isocyanate group), 1740cm-(ester carbonyl), 1458, 1350, 1200cm~l (e~ter ether).
Nuclear magnetic resonance spectrum: 1.2 to 2.4 ppm (8H), 3.2 to 3.8 ppm (~H, - CH2 - NC0), 3.9 to 4.6 ppm ,, NC0 (3H, - CH ).
~ ~ COO~H2 ~
Mass ~pectrum: m/c 153 (OCNCH2CH2CH2CH2CHNCO), 281 (molecular weight).
Example 1 . . a In a reactor provided with a ~tirrer, thermometer, a conden~er and a nitrogen gas introducing tube, after having sealed up nitrogen gas in it, 50 parts xylote and 50 parts butyl acetate were put, and the temperature was rai~ed to 90 to 95C. -, A mixture composed o~:
~tyrene 34.0 pts. -n-butyl. acrylate 38.0 pt~
2-hydroxyethyl methacrylate 23.4 pt3.
'f.ll, . . ~`.

~ 7 L~ f3 acrylic acid 0.4 pt.
azobisisobutyronitrile 1.2 pts.
was continuously dropped into the reactor over 3 hours, for polymerizing reaction. ~fter having finished drop-ping the mixture of monomers, the compound was stirred for 1 hour while it was heatcd. Thereafter, 0.7 part of azobisisobutyronitrilc was added 4 times at an interval of 30 minutes, and the compound was stirred for another hour to complete the whole reaction.
A resin solution thus obtained (a solution of polyacryl polyol) was colorless and transparent. Its Gardener bubble viscosity was "T" to ~'U" at 25C, and the content of nonvolatile matter 50%. The molecular weight (Mn) was 14500; value of hydroxyl group 50; and calculat-ed value of mean number of hydroxyl groups in a molecule 25.8.
This resin solution and LTI-E~ which had been previously prepared, were uniformly blended in such a manner that the amounts of hydroxyl and isocyanate groups are equal.
To this blended solution, a mixed thinner composed of of toluole and cello~olve acetate, in the ratio of 65/35 pct. by wt., wa~ added to adju~t the fluidity to 20 3ec.
at +4 o~ the Ford cup. '~hi~ diluted coating material was applied by ~praying on a mild ~teel ~heet prevlously coat-ed with primer surfacer No.ll~ (mfrd. by Kan~ai Paint Co.) and polished, in such a manner that the film thickness after drying would be approximately 40 ~, and the coat was let to harden at room temperature (23C) for a ~eeX.
The film coat obtained wa~, a~ i~ shown in ~able 1, hard and had an excellent re~istance to acid and hot water.
In re~pect of anti-yellowing property, too, it was equal to a coat obtained by the u3e of non-yellowing type i~o-, . ~.
cyanate prepolymers on the market.
- The concentration of carbamide group was 15.7 x 10-4 - moles/g; bridging parameter 501 and the percentage of hydrocarbon 301vent in the solvents¢ontained in the coat-ing material 59.

Example 2 l ., A coat was formed in the same manner as Example 1, ex-cept for, in thi~ example, the mixlng ratio of polyacryl :
. '., , - 3~ - ~
,., '~'',''.'',"~'~

. ~.,",, . _ _ ,,_ . ___. .. , ., . .... , . . ,.. .. 7:

1~74;~9~3 polyol solution and ~TI-E was 90 modified as to make the NCO/OH mole percentage 0.5. Properties and efficiency o~ the coat obtained are shown ln Table 1.
The concentration of carbamide group was 8.4 x 10-4 moles/g.; bridging parameter 947; and the percentage of hydrocarbon ~olvent in the solvents contained in the coat-ing material 59.
Example 3 A coat was formed in the same manner as Example 1, ex-cept for, in thi~ example, the mixing ratio o~ polyacryl polyol ~olution and LTI-E was 50 modi~ied a~ to make the NCO/OH mole percentàge 1.5. Properties and ef~iciency of the coat obtained are shown in Table 1. -~
. . . . .. ~.
~ The concentration of carbamide group was 22.0 x 10-4 ~ -~
mole/g.; bridging parameter 558; and the percentage of hydrocarbon solvent in the solvents contained in the coat- ;;.
ing material 58. ;/~
Example 4 ~`' In the sQme reaction apparatus as was used in Example 1, after having ~ealed up nltrogen gas in it, 80 parts .. , ,,';
. . '.~

- 37 - `~

i?
. _ _ __ __ __ _ _ _ _ _ _ ___ ___ _ ___ __ __ ___ ~

1~7~

xylole and 20 parts butyl acetate wer put, and the tem-perature was raised to 80 to 85C, A monomer mixture composed of:
styrene 25.0 pt5.
methyl methacrylate 25.0 pts, n-butyl methacrylate 21,0 pt~, n-butyl acrylate 14.0 pts, 2-hydroxyethyl methacrylate 12,0 pts, acrylic acld 0,7 pt.
azobi~isobutylonitrile 1,2 pts, was continuously dropped into the reactor over 3 hours.
. .
With the dropping finished, the compound waB heated and , stirred for 2 hour~, Sub~equently, 0,5 part o~ azobis-isobutylonitrile was added to the compound 4 times at an ~interval of 2 hours, and the compound was ~urther heated - J;~
and ~tirred for 3 hours to complete the whole polymeriz~
ing reaction, A resin ~olution thus obtained was colorles~ and trans- ;~
parent, It~ Gardener bubble viscosity (25C) was "V" to ;!;
"W", and the content of nonvolatile matter 50~. The mo-': . , ';'~
.~
, , ",~, ; - 38 - ~ ' ' . ,.''' .;'~, ~ . . . "
.
, ~.

: 11 7439~

lecula weight (Mn) was 11700; value o~ hydroxyl group 25; and calculated value of mean number of hydroxyl groups in a molecule 10.4.
With this resin ~olution, a coating material was pre-pared, applied and was let to harden in the same manner a~ Example 1. A~ ~hown in Table 1, a coat having a good luster, with satisfactory rise of hardness, an excellent re~istance to acid and hot water, wa~ obtained. In re-~pect of anti-yellowing property, too, the coat was as good as one obtained by the use of non-yellowlng type : ..
isocyanate prcpolymers available on the market, that is, no yellowing wa~ observed.
The concentration of carbamide group was 8.4 x 10-4 moles/g.; bridging paramster 1,067; ~nd the percentage o~ ;;
~ydrocarbon solvent in the solvent~ contained in the coat-ing material 71.
Exampl~ 5 To the re~in solution obtained in Example 4, LTI-P, which had been previou~ly prepared by polymerization, wa added in such a manner that the amounts of hydroxyl and .....
, ',', . , ..',,, . ~ .' . ,,~
. . ~

isocyanate groups are equal, and these are uniformly mixed together.
With this mixture, a coating material was pre-pared, applied and was let to harden in the same manner as Example 1. Properties and efficiency of the coat obtained are shown in Table 1.
l'he concentration of carbami~e group was 8.5 x 10 4 moles/g.; and bridging parameter 1031.
Control 1 A coat was formed in the same manner as Example 1, except for, in this case, the mixing ratio of polyacryl polyol solution and LTI-E was so modified as to make the NCO/OH mole percentage 2.50. Efficiency of the coat obtained is shown in Table 1.
The concentration of carbamide group was 32.4 x 10 4 moles/g.; and bridging parameter 633.
Control 2 A coat was formed in the same manner as Example 4, except for, in this case, the mixing ratio of the resin so-lution and LTI-E was so modified as to make the NCO/OII

~ - 40 -. ~
.c ..

:
mole percentage 0.5. Efficiency of the coat obtained is shown in Table 1.
The concentration of carbamide group was 4.4 x 10 4 moles/g.; and bridging parameter 1,999.
Control 3 ~ coat was formed in the same manner as Example 5, except for, in this case, the mixing ratio of the resin solution and LTI-P was so modified as to make the NCO/OII
mole percentage 0.5. Efficiency of the coat obtained is shown in Table 1.
, The concentration of carbamide group was 4.4 x moles/g.; and bridging parameter 1,966.

~ 41 -:

31~
.

O ~ _ _ _ _ _ _ _ _ e _ _ _ _ O~ t~
h H X X l l l l l l l l l l l l l l N0 ~3 1~ 3 X l l l l l l l l l l l l l l ~ N H X X l l l l l l l l l l l l l l h ~ Z;
~ ~ _ X l l l l l l l l l l l l l l ~, 01~

o ~ x x l l l l l l l l l l l l l l 'n x ~ P' _ _ _ _ _ _ _ _ _ ___ _ _ ~ ~` 11 h ~ ~:4 l l l l l l l l l l l l l l C-.~ 0:~
X H O Ol l l l l l l l l l l l l l ~ ¢ O X
~Ll -- - - - - - - - . - - - X t~4 X
_I U~ E~ O cl ~ h c X H O O~ n 1~ ~ In o o o o o ~ n ~ h X H O Ol l l l l l l ll l l l l ll i L.
~Ll --- - - - - - - --- -_~ Ul ~ ~ l l l i ~ ~ 1_1 ~ ~ l l l l l l l l l l l l l ll t~ ~ O O , , , , , , , , , , , , ;~

~a~ r-l H (~ ~) O O 1~7 E o o O O O O ~ ~ r~ 3 U

_ _ _ _ _ _ _ _ r _ _ _ -- r-l ~rl h h ~ h ,_ O :~ 't C . . . 111 rY ~d o h ~ X ~ ~ Z o h h h h @~ ~r h ul ~ ~`I ~ ~`I h O o\ In r~; v ~ r-l ~ ~r~
r-l O ~ ~ ~ x t~a In r; x _~ r ~1 O O O ~r1 h r h ~ _ ~Ll u) r-l P ~ O 1~ t~ ~r~ x O _ ~r~
o o u~ G ~ o G ~ G ~ ~ In G ~r1 a) a~ ~n u) O h t~ v~ u~
r-l ~ u~ ~ o \D t~ G ~ ~,~ o ~ ~ u~
P~ ~ ~t; ~ ~ i ~ ~ ~:: ~ G ~ ~ c~ a) h .r1 h ~ r-l ~ ~ h ~) ~1 ~ 0 -~d h -X 1 4~ h rC r ~ r1 ~ r1 G ~ h ~ r1 h ~ r1 . r1 I v~ h ~1 ~ a~ h a) ~ ~ a) ~ ~ ~rl ~ _~
~1 ~ O u~ C ~ ~ h G OO h ~ ~ G O
/ / H ~ vl O ~ O ~r1 O ~ ~r1 r-l r-l r-l H _ 11~ O
. V 3 Z ~ _ U5~ ~Ll h C c~ U~ O~Y ~

~'7'~131~

Example 6 Polyester polyol was prepared in the following : manner.
A mixture composed of:
neopentyl glycol 150.0 pts.
trimethylol propane22.1 pts.
adipic acid 72.3 pts.
isophthalic acid 123.2 pts.
was put in a reactor and was stirred for 30 minute while heating it at 200C. Then, until it reached an acid value of 10 and a C~l value of 150, heating and stirring were continued at a temperature of 220C, thus distilling water (approx. 15 hrs.). The molecular weight of the reaction product obtained was approximately 1000. By adding butyl acetate to this reaction product while it is being cooled, a solution with 70% solid matter content -- a - ~3 -~7~ B

polyester polyol solution -- was prepared.
In the next place, LTI-E was added to this polyester polyol solution in such a manner that the amounts of hydroxyl and isocyanate groups are equal, and these were uniformly mixed together. The calculated value of the concentration of carb-amide group of this reacti.on product was 21.8 x 10 4, and the calculated value of bridging parameter E 790.
A film coat which was obtained by applying this coating mixture and letting it harden had an excellent luster and very good mechanical properties.
The percentage of hydrocarbon solvent in the sol-vents contained in said coating material was 48.
Example 7 A two-component type polyurethane coating consist-ing of "A" and "B" liquids, as undermentioned, was prepared.
; "A" liquid: 171.6 parts polyacryl polyol of Ex-ample 1 and 57.2 parts titanium oxide were kneaded in a three-roller kneading machine to form a pastc.

~7~

"B" liquid: 7.8 parts xylole was added to 14.2 parts LTI-E to form a triisocyanate solutioll with an NCO content of 30 wt.%
By mixing equal amounts of "A" and "B" liquids, a mixture of NC0/0~1 - 1 was obtained. By adding a thinner (toluole/cellosolve acetate = 65/35 wt.pct.) to this mix-ture, the fluidity was adjusted to 15 sec. of the Ford cup #4. The content of nonvolatile matter in the solu-tion was 55 %. This diluted solution was applied by spray-ing on a mild steel sheet previously coated with a primer surfacer and polished, such as was used in Example 1, in such a manner that the film thickness after drying would be approximately 40 ~, and the material was heated at 60C for 30 minutes. The coat obtained had a good luster and was superior in respect of acid and solvent resist-ance, too. The gloss retention after exposure outdoors for 18 months was approximately 70%, thus proving to have a very good weather resistance.
Concentration of carbamide group: 15.7 x 10 4 moles/g.
Bridging parameter: 501 Percentage of hydrocarbon in the solvents: 57.1~.

3~3 Example 8 To 14.2 parts LTI-E of the "B" liquid in the case of Example 7, methyl ethyl ketoxime in an amount equal to that of NCO group was added, and the mixture was stirred for 5 hours at room temperature to block ~CO group of LTI-E. By adding 7.8 parts xylole to this blocked isocyanate, a triisocyanate solution with an NCO content of 30 wt.% at the time of dissociation was prepared.
By mixing this solution with "A" liquid of Example 7, a one-liquid type polyurethane coating was prepared.
The coating material was diluted with a thinner, and was applied on the base material in the same manner as Example 7.
After the coating had set, the material was heated at 150C for 30 minutes to form a finished coat. The polyurethane resin coat obtained had a superior luster and showed a satisfactory weather resistance.

, - 46 -

Claims (12)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A polyurethane resin having an excellent weather resistance, which is a reaction product obtained by causing (A) a polyol to react with (B) a trifunctional isocyanate which is expressed by the following general formula:

(R = a remnant of divalent hydrocarbon group with the carbon number of 2 or 3) at an NCO/OH mole percentage of 0.5 to 2.0; and of which the concentration of carbamid group is 5 x 10-4 to 50 x 10-4 moles per gram of said reaction product, and the bridging parameter 150 to 1,500.

2. A polyurethane resin as claimed in Claim 1, wherein the molecular weight of polyol is in the range of 500 to 5,000.

3. A film coat having an excellent weather resistance, whereof the main ingredient is a polyurethane resin which is a reaction product obtained by causing (A) a polyol to react with (B) a trifunctional isocyanate which is expressed by the following general formula:

(R = a remnant of divalent hydrocarbon group with the carbon number of 2 or 3) at an NCO/OH mole percentage of 0.5 to 2.0; and of which the concentration of carbamide group is 5 x 10-4 to 50 x 10-4 moles per gram of said reaction product, and the bridging parameter 150 to 1,500

4. A film coat as claimed in Claim 3, wherein the mole-cular weight of polyol is in the range of 500 to 5,000.

5. A film coat as claimed in Claim 3, wherein the polyol used is a polyester polyol of which the molecular weight is in the range of 500 to 1,000.

6. A film coat as claimed in Claim 3, wherein the polyol used is a polyacryl polyol of which the molecular weight is in the range of 1,000 to 3,000.

7. A film coat as claimed in Claim 3, wherein the NCO/OH mole per-centage is in the range of 0.5 to 1.2.

8. A film coat as claimed in Claim 6, wherein the polyacryl polyol used is a copolymer composed mainly of hydroxyalkyl acrylate and/or hydroxy-alkyl methacrylate, and alkyl ester of acrylic acid and/or alkyl ester of methacrylic acid,

9. A two-component type polyurethane resin coating composed of:
(A) a kneaded mixture of a polyol and a pigment which is added to it at need; and (B) a trifunctional isocyanate which is expressed by the follow-ing general formula:

(R = a remnant of divalent hydrocarbon group with the carbon number of 2 or 3) and which has been diluted with a solvent at need, the amount of solvent in (B) being O to 50 pct. by wt.

10. A coating as claimed in Claim 9, wherein more than 50 pct. by wt.
of the solvent used and the thinner added at need is hydrocarbon solvents.

11. A one-component type polyurethane resin coating whereof the main ingredients are: a polyol and a trifunctionl isocyanate which is expressed by the following general formula:

(R = a remnant of divalent hydrocarbon group with the carbon number of 2 or 3) and of which the isocyanate group has been blocked with a blocking agent, i.e., a blocked isocyanate.

12. A coating as claimed in Claim 11, wherein more than 50 pct. by wt.
of the solvent which is added at need is hydrocarbon solvents.