CA1050580A - Golf club with polyurethane insert - Google Patents

Abstract

GOLF CLUB WITH POLYURETHANE INSERT
Abstract of the Disclosure Golf clubs are provided with poly-urethane inserts on the striking face.
These golf clubs have been found to have advantage over standard golf clubs in that a golf ball hit with these clubs travels a greater distance, all other conditions being equal.

Description

~s~s~ l The present invention relat2s to an improvement in golf clubs known as "wood.s." "Woods" comprise a shaft,.a club head.block and. usually an insert on the striking face of the club head block. The improvement of the present inv~ntion comprises a polyurethane.insert on the striking face of the golf - club. When all other conditions remain the same the golf club with the polyurethane insert will drive a golf ball ~ur~her than a s~andard. golf club.
.D In the game of golf it is usually desired. to get the greatest possible d.istance with the golf clubs known as "wood.s." While many changes have been mzd.e .
in golf balls in ord.er to increase the d.istance they will travel, the applicants have d.iscovered. a change ~ which can be mad.e in the golf club in ord.er to increase ~ ~ the d.istance which the golf-ball will travel. Hereto-fore, many different materials have been tried. for the insert in golf club head.s, including ivory, ste~l, aluminum and. many d.ifferent plastic compositions. In ~0 choosing the insert, current thinking is that it should ~.
be as hard. as possible so that no dynamic losses of :
- .
. . energy take place when the insert impacts the ball. -Commonly used. materials today ~or the insert are . . laminated. phenolics which are quite hard. materials as is exemplified by the fact that they usually have : -

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a Rocl~well hardness from about M90-120 for typical golf club inser-ts. .
The applicants have now discovered. that it is not always necessar~ to use a hard. material for -~he insert and that, in fact, there is advantage in using polyurethane which is a relatively soft material with a Shore D hardness up to about 80. Quite surprisingly, the resilience of the polyurethane seems to impart - ad.d.itional energy to the golf ball rather than causing O losses of energy as was previously thought to be true ¦
of relat;vely soft ~aterials. .
The polyurethanes which were useful in the practice of the present ir.vent~on are the uret:hane pre-polymers .. , - i mad~ from polyesters ~r polyethers wi~h d.iisocyanate~
: Although any d.iisocyanate may be employed., the preferred.
diisocyanates are 2,4 tolylene d.iisocyanate (TDI), -. 4~4' d.iphenylmethane diisocyanate (MDI), and. 3,3' ~: dimethyl 4-,4' biphenylene d.iisocyanate (also kno~n as

3,3' dimethyl 4,4' biphenyl d.iisocyanate) (TODI). The !O polyether part of the pre-polymer is preferably a poly-alkylene ether glycol having an average molecular weight of less than 1,000 and. having from about 4 to about 8 carbon atoms in the alkylene group. Best .~ results have been obtained. with polytetramethylene . .`
I ethe~r glycol~ The preferred. polyesters in the pre-polymer., 3 , ' ' i8~ i are polycondensation products of linear dicar~oxyllc acids and d.ihydric alcohols which yield. a polyester with alcoholic hydroxy terminal groups. Best results have been obtained with the polycondensation product of die-thylene glycol and adipic acid..
The pre-polymer is cured with either a polyol or an amine-type curing agent. The polyol c~ri.ng agents may be either d.i-functional, tri-functional or tetra-functional but best results have been ach~.eved.with ~O the tri-functional and. tetra-func~ional polyol curing agents. Examples of polyol type curing agents useful in the practice of the present invention are triisopropanol~ -Emine (TIPA) and trimethylol propane (T~). Best ` results have bePn obtained. with the '~P. As to the :~
amine-type curing agents, there must be at least ~lo amine groups present and best results have been obtained.
with aroma~ic d.iamine~. Typical amine-type curing agents which are use~ul in the practice of the present ~ :invention are: 3,3' dichlorobenzid.ene; 3,3' dichloro, -'O 4,4' d.iamino diphenyl methane (MOCA); N,N,N'~N' tetrakis (2-hydroxy propyL) ethylene d.iamine (sold by Wyand.otte .. :
und.er the trade name Quadrol); and. Curalon L which is Uniroyal Inc.'s brand.name for a mixture of aromatic diamines. ........................................................... .
In forming the insert oE the present invention

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the pre-polymer and the curing agenL a e mixed. in an equivalent weight ratio of 1~ 20% and.best results h~ve been obtained with an equivalent weight ratio of 1:1~ 10%. The amount of curing agent to be ad.ded. .
is computed. in the following formula:
;.
C = (Ec) (%I) (EI) w~erein: ' C = the parts of curing agent to be employed. .
.0 per 100 parts of prepolymer;
~ EI = the equivalent weight of the isocyanate :: ~ linkage in the prepolymer (which will be - 42.0);
.%I = the percentage b~ weight o~ available : .. isocyanate in the prepol~y~er; and.
~ -: .
EC = the equivalent weight of the curing agent (d.etermined.by d.ividing the molecular weight of the curing agent by the number - : of sites available for curing).
~ . . : .
.-.~0 The above formula will result in an equivalent weight.
ratio of l:l for curing agent to prepolymer. The .. amount of curing agent may then be varied. ap to 20% ~ ~
~n either d.irection. A computation accord.ing to the ~ -abave ormula is given in Example 1.

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As a general rule the pre-polymer and the curing agent are thoroughly mixed at a temperature ranging , , from arn~ient to 250F. and then are formed into the shape of an ins~rt as by open casting, compression molding, transfer molding or other known techniques.
The insert is then cured and this is,typically at : from about 200F. to about 300F. for about 1 to about 24 hours. The curing time can be d.ecreased in known manner by using catalysts (e.g., stannous octoate where ,'0 the polyol-type curing agent is used,).
, . - ~ile the polyurethane insert has been d.escribed, . ~ :
.... , ~
with respect to particular pre-poly~ers and. curing .
''' ~ agents, it has been found. that a pol~J~reLhane insert , , .'`

: havir.g the ad.v,r.ta~es of th~ preer.t inve~tion ~

always be obtained. if the pre-polymer and. curing agent `' , ; . . .
: ' . are selected to yield. a ~cmpound with the following . ~
, physical properties: tensile strength-from about 1,500 , . ~ .-' '1, to about 8,000 psi as measured.by ASTM Standard. D 412, . .
hardness from about 40 to about 75 on the Shore d.urometer O D scale accord.ino to ASTM Standard D 2240, elon~ation ' . from about 50% t~ about 3Q0% as measured,by ASTM Standard.

.' ~ D 412, rebound value on a Bashorè Resiliometer as .
measured.by ASTM Standard D 2632-67, above about 17 and.

: ' preferably from about 33 to about 48, Th~se and. other aspects o~ the present invention ", I ~".
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may be more fully understood wi-~h reference to the drawing and illustrative e~amples as set out herein-below. - .
- In the drawing is sho~m a stand.ard. golf club 10 with shaft 12 (not completely shown), club head block 14, inser~ 16 and screw attachment means 18. The club head shaft 12 may be made of any stand.ard material sueh as steel, aluminum, fiberglass or the new light~
weight alloys. The club head block 14 may likewise be mad.e of any stand.ard material such as aluminum or wood., and the preferred. club head.block is mad.e of persi~mon wood., The plastic ïnsert 16 a~cord.ing to the ., .
present invention is mad.e Gf po'-rurethane as d.escribed. ' ~

in this specificativ~. The insert in the preferred. ,.
.. . .
embod.iment is a truncated. triangle about 1/4" thick :~ b~t the insert may be in any shape desired., and may cover the entire face of the club head. if d.esired..
Excellent results are obtained when tha insert is from about 3/16" to about 7/16" thick. The insert 16 'O ~ is firmly secured to the club head block 14 by any - means although the preferred. means comprises an adhesive between the club head. block and. the :insert and also screw attachment means 18 as shown in the d.rawing.
While the club head ~ace is sho~m with grooves therein, these grooves are not essential to obtain ~he improved ' j ' ' ' t ~ , , ' ,,1, ' ' ;'~' ,' ""'"" ' '; ~ ;' ' , .
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distance impar~ed by the polyurethane inserts of the present invention. The completed. club head. may be coated. with a finish in conventional manner.
The follo~Jing are representative exa~ples of . polyurethane inserts made in accordance ~7ith the present invention:

100 parts of Ad.iprene 315 pre-polymer was admixed.
with 14 parts of triisopropanol amine, which was the .. curing agent. Ad.iprene 315 is DuPontis trad.emark for : a ure~hane pre-polymer which is a product of a poly-: tetrame.hylene ~ther glycol and. tolyl2;L2 d.iisocyanate.
The a~ount of curln~ agen-t to be ad~.ed was com~llted . ...
from the for~ula:
.
C = (Ec) (%I~
(EI) i ~ .
, wherein:
., .
C = the parts of curing agents to be employed. .

- per 100 parts of pre-polymer;
.
!0 . ~ EI = ~he equlvalent weight of the isocyanate . linkage~in the pre-polymer and. is 42.0; `.
%I = the percentage by weight of available isocyanate in the pre-polymer and is 9.Z5%; ~ -and. : .
i~ ' ' . ~ ..
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.

., ,, , , ,~ .
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EC = the equivalent weight of the curing agent.
- The molecular wei~ht of triisopropanol amine is 191.27. Since there are three sites available for curing, the equivalent weight of the curin~ agent is 63.76. .. A
Substituting these values in the for~ula, C - (63.76) (9.25) - 14 parts . ~2 j - .
0 As sta~ed hereinbefore9 the mole ratio of the pre~ .
-~ . polymer to the curing agent is 1:1+ 20%. Therefore, the parts of triisopropanol amine which can be add.~d.
per 100 parts of Ad.iprene 315 is about 11.2 parts to . ~ about 16.8 parts. In the present e~ample, 14 parts : of the curing agent were employed..
:After the pre-polymer and. the curing agent were -: thoroughly admixed. at 250F., the product was cast to a ,- :
thickness o about 1/4". The cast p:rod.ut was then , press cured for 15 minutes at 230F. removed. from the .
~'0 mold. and oven cured. for 3 hours at 230F. The cast , -product:was then cut into the shape of an insert for a wooden type golf club, and. the insert was shaped.
essentially as shown in the Figure. Ihe golf club wi~h the polyurethane insert was then compared. to a , ~ .
gol~ club having a standard phenolic insert. The :
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1 ~5~ ~ 8 golf club with the phPnolic insert was the same ln alL
respects to the golf club with the polyurethane insert except for the inserts themse'ves. In a number of tests on a golf ball driving machine, golf balls hit with the club having the polyurethane insert travelled.
further than golf balls hit with the same golf club having a phenolic insert. This increased. distance .
was from 1-5 yard.s on a 250 yard. driveO
. .
~XAMPLE 2 A polyurethane insert was mad.e in accordance with ., , Example 1 except tha~ 11.2 parts o triisopropanol ~: amine was used. per 100 parts of ~d.iprene 315. Com- ' -parable results were obtained.

~; ~ EXAMPLE 3 -A polyurethane insert was mad.e in accord.ance with Example 1 except that lfi.8 parts of triisopropanol amine were used per lOO.parts of Ad.iprene 315. Com-parable results were obtained......................................... ~:

' !0 A polyurethane insert was made in accordance with .
. , Example 1 from 100 parts of Adiprene 315 and. 29.4 parts of 3,3' dichloro 4,4' diamino diphenyl methane. When .

.: ' ~ 5~ 5 ~ ~ i the polyurethane insert was tested. in a golf club, there ; was significant i.mprovement in yardage as compared to a comparable club having a phenoli.c insert.

.. . ...
In this case 100 parts of Ad.iprene 315 wereeured with ~.85 parts of trimethylol propane accord.ing to the method. taught in Example 1. Com-parable results to those given in Example 1 were obtained..
- .
!0 EXAMPLE 6 , ~- A polyurethane insert was formed from lOQ parts . ~ -of ~d.iprene LD 355 aIld. was cured.-with 15.1 parts of ;`~ N,N,N',N' tetrakis (2-hyd.roxypropol) ethylene d.iamine . . . according to the procedure of Example 1. Comparable - results to those given in Example 1 were obtained.. :

: ~ ~ EXAMPLE 7 In this example a pre-polymer which is a product ~ ~.
!
of a glycol ad.ipic acid ester and. tolylene d.iisocyanate . was used... 100 parts of the pre-poLymer was cured.with ~0 29.6 parts of 3,3' dichloro ~,4l di.amino diphenyl 1.
methane accord.ing to the method of Example 1.. When the polyurethane insert was tested. in a golf club, . . .
,.,", ' , j.
~ , ~ ~ 5 comparable results to ~hose of Example 1 were obtained A polyurethane insert was formed. from 100 parts of the pre-polymer of Example 7 cured. with 33.1 parts of Curalon L (Uniroyal Inc.'s brand. name for .~
a mixture of aromatic diamines) accord.ing to the method. of Example 1. When the polyurethane insert was compared to a phenolic insert as in Example 1, .
a significant increase in yard.age was obtained, . , .

'~ A polyure-Lhane insert was mad.e with 100 part3 : ~ , . -.
-~ Ad.iprene 315 and 33 parts of Cur~lon Z accordin~ to the method. of Example 1, Comparable results to those . o~ Example 1 were obtained.

:; EXAMPLE 10 - A polyurethane insert was formed from 100 par~s of Adiprene 315 cured. with Z7.8 p~arts of dichloro- .
benzidene according to the m.ethod of Example 1. When ' the polyurethane insert was compared. to a phenolic .
insert, a signi~icant improvement in distance was ;
obtained...................................................... i . -12-, . ', .

- , . v ; . :, PHYSICAL PROPERTIES - i , ~

All of the polyurethane inserts of Examples l-lO had physical properties within the following limitations: -Tensile strength from about 1,500 to about .
8,000 psi as measured by ASTM Stand.ard. D 412;
Hardness from about 40 to about 75 on theShore Durome~er D Scale accord.ing to ASTM Stand.ard.
D 2240; . -~
~` Elongation from about 50% to about 300% as measured. by ASTM Stand.ard. D 412;
Rebound. value on a Bashore Resiliometer as measured by ASTM Stand.ard. D 2632-67, above about .

.
It will be understood that the cl~ims are .
. intend.ed. to cover all changes and. modifications of the preferred. embodiment of the invention, herein chosen for the purpose of illustration, which do not con.stitute d.epartures from the spirit and. scope of ~ i the invention. o -13- ~

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Claims (10)

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

1. In a golf club comprising a shaft and a club head, the improvement which comprises a polyurethane striking plate affixed to the striking face of the club head, the polyurethane striking plate being formed from a prepolymer selected from the group consisting of polycondensation products of polyesters and polyethers with diisocyanates, and a curing agent for the prepolymer selected from the group consisting of trifunctional polyols, tetrafunctional polyols and amine compounds having at least two amine groups, the prepolymer and the curing agent being in an equivalent weight ratio of 1:1?20%, the striking plate having a thickness of from 3/16" to 7/16" and said strik-ing plate having a tensile strength from about 1,500 psi to about 8,000 psi as measured by ASTM Standard D 412, a hardness from about 50 to about 75 on the Shore Durometer D Scale accord-ing to ASTM Standard D 2240, elongation from about 50% to about 300% as measured by ASTM Standard D 412, and a rebound value above about 17 on a Bashore Resiliometer as measured by ASTM
Standard D 2632 67.

2. The golf club of claim 1 wherein the rebound value is from about 33 to about 48.

3. The golf club of claim 1 wherein the prepolymer and the curing agent are in an equivalent weight ratio of 10%.

4. The golf club of claim 1 wherein the diisocyanate is selected from the group consisting of 2,4 tolylene diisocy-anate, 4,4' diphenylmethane diisocyanate, and 3,3' dimethyl 4,4' biphenylene diisocyanate.

5. The golf club of claim 1 wherein the prepolymer is a polyether with a diisocyanate and the polyether is a poly-alkylene ether glycol having an average molecular weight of less than about 1,000 and having from about 4 to about 8 carbon atoms in the alkylene group.

6. The golf club of claim 5 wherein the polyether is polytetramethylene ether glycol.

7. The golf club of claim 1 wherein the prepolymer is a polyester with a diisocyanate and the polyester is a poly-condensation product of a linear dicarboxylic acid and a di-hydric alcohol, said polycondensation product having alcoholic hydroxy terminal groups.

8. The golf club of claim 7 wherein the polyester is a polycondensation product of diethylene glycol and adipic acid.

9. The golf club of claim 1 wherein the curing agent is an aromatic diamine.

10. The golf club of claim 1 wherein the curing agent is selected from the group consisting of triisopropanol amine, trimethylol propane, 3,3' dichlorobenzidene, 3,3' dichloro 4,4' diamino diphenyl methane, and N,N,N',N' tetrakis (2-hydroxy propyl) ethylene diamine.