WO2019177924A1

WO2019177924A1 - Adhesive compositions

Info

Publication number: WO2019177924A1
Application number: PCT/US2019/021534
Authority: WO
Inventors: Jia Wen Xiong; Xiang Yang Tai; Huan CHEN; Wolfgang SUN; Juelin LIU
Original assignee: Dow Global Technologies Llc
Priority date: 2018-03-15
Filing date: 2019-03-11
Publication date: 2019-09-19
Also published as: CN110272708A

Abstract

Embodiments of the present disclosure are directed towards adhesive compositions that include a reaction product formed by reacting a diphenylmethane diisocyanate component and a polyol, and an aliphatic isocyanate.

Description

ADHESIVE COMPOSITIONS

Field of Disclosure

[0001] Embodiments of the present disclosure are directed towards adhesive compositions, more specifically, embodiments are directed towards adhesive compositions that include a reaction product formed by reacting a diphenylmethane diisocyanate component and a polyol, and an aliphatic isocyanate.

Background

[0002] Polyurethane compositions have been used as adhesives, composites, coatings, and sealants, among other applications. One-part polyurethane compositions can be moisture curable. Different properties of these compositions and/or the curded products obtained therefrom may be desirable for various applications.

Summary

[0003] The present disclosure provides adhesive compositions including a reaction

product formed by reacting from 15 to 50 weight percent of a diphenylmethane

diisocyanate component and from 50 to 85 weight percent of a polyol, based upon a total weight of the diphenylmethane diisocyanate component and the polyol; an aliphatic

isocyanate, wherein the aliphatic isocyanate is from 0.5 to 20 weight percent based upon a total weight of the diphenylmethane diisocyanate component, the polyether polyol, and the aliphatic isocyanate.

[0004] The above summary of the present disclosure is not intended to describe each disclosed embodiment or every implementation of the present disclosure. The

description that follows more particularly exemplifies illustrative embodiments. In

several places throughout the application, guidance is provided through lists of examples, which examples can be used in various combinations. In each instance, the recited list

serves only as a representative group and should not be interpreted as an exclusive list.

Detailed Description [0005] Adhesive compositions, including a reaction product formed by reacting a diphenylmethane diisocyanate (MDI) component and a polyol, and an aliphatic isocyanate are disclosed herein. These adhesive compositions may be referred to as one- part compositions. These adhesive compositions are moisture curable.

[0006] Advantageously, the adhesive compositions disclosed herein can provide an improved, i.e., greater, tack free time as compared to other one-part compositions. Tack free time, also referred to as gel time, is a time interval over which a sample of the composition becomes non-tacky to the touch after exposure of the composition to moisture, e.g. ambient air. Greater tack free times are desirable for a number of applications, e.g., where the settling of components can be a consideration, such as some composite applications for instance.

[0007] Further, the adhesive compositions disclosed herein advantageously do not utilize a number of isocyanates that may be undesirable for a number of applications. For instance, the adhesive compositions disclosed herein advantageously do not utilize toluene diisocyanate, and/or hexamethylene diisocyanate. These isocyanates may be undesirable for a number of reasons, such as material safety, e.g., high vapor pressure, unsatisfactory mechanical properties of products made therefrom, and/or high price. In contrast to compositions that utilize toluene diisocyanate, and/or hexamethylene diisocyanate, as mentioned, the adhesive compositions disclosed herein include a reaction product formed by reacting a diphenylmethane diisocyanate component and a polyol.

[0008] As mentioned, the adhesive compositions disclosed herein include a reaction product formed by reacting a diphenylmethane diisocyanate component and a polyol.

The diphenylmethane diisocyanate component may include from 90 to 100 weight percent of 4,4'-diphenylmethane diisocyanate percent based upon a total weight of the diphenylmethane diisocyanate component. All individual values and subranges from 90 to 100 weight percent are included; for example, the diphenylmethane diisocyanate component may include from a lower limit of 90, 93, or 95 weight percent to an upper limit of 100, 99, or 97 weight percent of 4, 4'~dipheny [methane diisocyanate based upon the total weight of the diphenylmethane diisocyanate component. The diphenylmethane diisocyanate component may also include 2,2‘~ diphenylmethane diisocyanate, 2,4 - diphenyimethane diisocyanate, and/or impurities known in the art. [0009] Embodiments of the present disclosure provide that the polyol has a weight average molecular weight from 300 to 12,000 g/mo!. All individual values and subranges from 300 to 12,000 g/mof are included; for example, the polyol can have a weight average molecular weight from a lower limit of 300; 500; 750; 1,000; 1,250; 1,500;

1,750, 2,000; or 2,250 g/mol to an upper limit of 12,000; 11,000; 10,000, 9,000; 8,000; 7,000; 6,000; 5, 00; or 4,500.

[0010] Embodiments of the present disclosure provide that the polyol has an average functionality from 1.5 to 3.5. All individual values and subranges from 1.5 to 3.5 are included; for example, the polyol can have an average functionality from a lower limit of 1.5, 1.6, 1.7, or 1.8, to an upper limit of 3.5, 3.4, 3.3, or 3.2.

[0011] Embodiments of the present disclosure provide that the polyol can be a polyether polyol, a polyester polyol, and combinations thereof. Examples of

commercially available polyols include, but are not limited to, polyols sold under the trade name VORANOL™, such as VORANOL™ WD 2130 and VORANOL™

4000LM, TERCAROL™, and VORATEC™, among others. One or more embodiments of the present disclosure provide that the polyol can include a polyether polyol.

Polyether polyols can be prepared by known processes. For instance, polyether polyols can be prepared by anionic polyaddition of at least one alkylene oxide, e.g., ethylene oxide or 1,2-propylene oxide or 1,2-propylene oxide and ethylene oxide. A starter compound, which may be referred to as an initiator is any organic compound that is to be alkoxylated in the polymerization reaction. The initiator may contain 2 or more hydroxyl and/or amine groups. Mixtures of starter compounds/initiators may be used. Examples of initiator compounds include, but are not limited to, ethylene glycol, diethylene glycol, tri ethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, 1,4-butane diol, 1,6-hexane diol, 1,8-octane diol, cyclohexane dimethanol, glycerin,

trimethylolpropane, trimethylolethane, pentaerythritol, sorbitol, sucrose, as well as alkoxylates (especially ethoxylates and/or propoxylates) of any of these, polyamines, dialkanolamines.

[0012] One or more embodiments of the present disclosure provide that the polyol can include a polyester polyol. Polyester-polyols may be prepared from, for example, organic dicarboxylic acids having from 2 to 12 carbon atoms, including aromatic dicarboxylic acids having from 8 to 12 carbon atoms and polyhydric alcohols, including diols having from 2 to 12 carbon atoms. Examples of suitable dicarboxylic acids are succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, and the isomeric naphthalene-dicarboxylic acids. The dicarboxylic acids may be used either individually or mixed with one another. Free dicarboxylic acids may be replaced by a corresponding dicarboxylic acid derivative, for example, dicarboxylic esters of alcohols having 1 to 4 carbon atoms or dicarboxylic anhydrides. Some particular examples may utilize dicarboxylic acid mixtures including succinic acid, glutaric acid and adipic acid in ratios of, for instance, from 20 to 35:35 to 50:20 to 32 parts by weight, and adipic acid, and mixtures of phthalic acid and/or phthalic anhydride and adipic acid, mixtures of phthalic acid or phthalic anhydride, isophthalic acid and adipic acid or dicarboxylic acid mixtures of succinic acid, glutaric acid and adipic acid and mixtures of terephthalic acid and adipic acid or dicarboxylic acid mixtures of succinic acid, glutaric acid and adipic acid. Examples of dihydric and polyhydric alcohols are ethanediol, diethylene glycol, 1,2- and 1, 3-propanediol, dipropylene glycol, l,4-butanediol, l,5-pentanediol, l,6-hexanediol, l,lO-decanediol, glycerol,

trimethylolpropane, among others. Some particular examples provide that ethanediol, diethylene glycol, l,4-butanediol, l,5-pentanediol, l,6-hexanediol or mixtures of at least two of said diols, in particular mixtures of l,4-butanediol, l,5-pentanediol and 1,6- hexanediol. Furthermore, polyester-polyols made from lactones, e.g., e-caprolactone or hydroxycarboxylic acids, e.g., w-hydroxycaproic acid and hydrobenzoic acid, may also be employed.

[0013] Polyester polyols can be prepared by polycondensing organic polycarboxylic acids and/or derivatives thereof with polyhydric alcohols in a molar ratio of from 1 : 1 to 1 : 1.8, e.g., from 1 : 1.05 to 1 : 1.2, for instance.

[0014] The reaction product can be formed by reacting from 15 to 50 weight percent of the diphenylmethane diisocyanate component and from 50 to 85 weight percent of a polyol, based upon a total weight of the diphenylmethane diisocyanate component and the polyol. All individual values and subranges from 15 to 50 weight percent of diphenylmethane diisocyanate component are included; for example, the reaction product can be formed by reacting from a lower limit of 15, 20, or 25 weight percent to an upper limit of 50, 45, or 40 weight percent of diphenylmethane diisocyanate component, based upon the total weight of the diphenylmethane diisocyanate component and the polyol.

All individual values and subranges from 50 to 85 weight percent of the polyol are included; for example, the reaction product can be formed by reacting from a lower limit of 50, 55, or 60 weight percent to an upper limit of 85, 80, or 75 weight percent of the polyol, based upon the total weight of the diphenylmethane diisocyanate component and the polyol. The reaction product may be referred to as pre-formed, as the reaction product is formed prior to being combined with the aliphatic isocyanate.

[0015] The reaction product can be formed using known equipment and reaction conditions. For instance, the reactants, i.e. the diphenylmethane diisocyanate component and the polyol may be heated to any desirable temperature, for a specified time sufficient to effectuate a desirable chemical/physical transformation. As an example, the reaction product can be formed at a temperature from 20 °C to 100 °C; the reaction may occur, e.g. be maintained, from about 5 minutes to about 8 hours; and the reaction may occur in an inert environment, such as a nitrogen environment.

[0016] The adhesive compositions disclosed herein include an aliphatic isocyanate.

The aliphatic isocyanate may be combined with the reaction product from 1 minute to 12 hours after the reaction product is formed, for example. All individual values and subranges from 1 minute to 12 hours are included; for example, the aliphatic isocyanate may be combined with the reaction product from a lower limit of 1, 3, 5, 10, or 30 minutes to an upper limit 12, 10, 8, 6, or 4 hours.

[0017] Embodiments of the present disclosure provide that the aliphatic isocyanate has an average functionality from 1.5 to 3.5. All individual values and subranges from 1.5 to 3.5 are included; for example, the polyol can have an average functionality from a lower limit of 1.5, 1.6, 1.7, 1.8, or 2.0 to an upper limit of 3.5, 3.4, 3.3, 3.2, or 3.0.

[0018] Examples of aliphatic isocyanates include, but are not limited to, isophorone diisocyanate, isophorone diisocyanate trimer, hexamethylene diisocyanate trimer, methylene dicyclohexyl diisocyanate, and hydrogenated methylene dicyclohexyl diisocyanate. One or more embodiments of the present disclosure provide that the aliphatic isocyanate is selected from isophorone diisocyanate, isophorone diisocyanate trimer, hexamethylene diisocyanate trimer, and combinations thereof.

[0019] The adhesive compositions disclosed herein include 0.5 to 20 weight percent of the aliphatic isocyanate based upon a total weight of the diphenylmethane diisocyanate component, the polyol, and the aliphatic isocyanate. All individual values and subranges from 0.5 to 20 weight percent are included; for example, the adhesive composition can include from a lower limit of 0.5, 0.7, 1.0, or 2.0 weight percent to an upper limit of 20, 18, 15, 10, 8, or 6 weight percent of the aliphatic isocyanate based upon the total weight of the diphenylmethane diisocyanate component, the polyol, and the aliphatic isocyanate.

[0020] The aliphatic isocyanate may be utilized in a weight ratio with the

diphenylmethane diisocyanate component from 1 :2Q to 1 :5. All individual values and subranges from 1 :5 to 1 :20 are included; for example, the aliphatic isocyanate may be utilized in a weight ratio with the diphenylmethane diisocyanate component from a lower limit of 1 :20, 1 : 18, or 1 : 16 to an upper limit of 1 :5, 1 :5.5, or 1 :6.

[0021] The adhesive compositions disclosed herein may optionally include a quaternizing agent. Examples of quaternizing agents include, but are not limited to, alkyl halides, aralkyl halides, dialkyl carbonates, dialkyl sulphates, epoxides, and combinations thereof. Examples of particular quaternizing agents include, but are not limited to, methyl chloride, ethyl chloride, benzyl chloride, methyl bromide, ethyl bromide, benzyl bromide, dimethyl sulfate, diethyl sulfate, ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, and combinations thereof. One or more embodiments of the present disclosure provide that the quaternizing agent is benzyl chloride.

[0022] The adhesive compositions disclosed herein may include 20 to 200 parts per million of the quaternizing agent based upon the total weight of the diphenylmethane diisocyanate component and the polyol. All individual values and subranges from 20 to 200 parts per million are included; for example, the adhesive composition can include from a lower limit of 20, 30, or 50 to an upper limit of 200, 175, or 150 parts per million of the quaternizing agent, based upon the total weight of the diphenylmethane

diisocyanate component and the polyol.

[0023] One or more embodiments of the present disclosure provide that the adhesive composition can include an additive. Examples of additives include, but are not limited to, organic acids, phosphoric acids, fillers, thixotropic agents, antioxidants, pigments, UV absorbers, adhesion promoters, drying agents, and combinations thereof, among others. Different amount of the additive may be utilized for various applications.

[0024] The adhesive compositions can be prepared, e.g., mixed, combined, under conditions known for one-part, moisture curable compositions.

[0025] The adhesive compositions disclosed herein can have an NCO content from 3.0 to 12.0 weight percent, based upon a total weight of the adhesive composition. All individual values and subranges from 3.0 to 12.0 weight percent are included; for example, the adhesive composition can have an NCO content from a lower limit of 3.0, 5.0, or 7.0 weight percent to an upper limit of 12.0, 11.0, or 10.0 weight percent based upon the total weight of the adhesive composition.

[0026] The adhesive compositions disclosed herein can have a viscosity at 25 °C from 1,000 to 6,000 mPa s, as determined according to ASTM D4889. All individual values and subranges from 1,000 to 6,000 mPa s are included; for example, the adhesive composition can have a viscosity at 25 °C from a lower limit of 1,000; 1,250; or 1,500 mPa s to an upper limit of 6,000; 5,000; or 4,500 mPa s , as determined according to ASTM D4889.

[0027] As mentioned, the adhesive compositions disclosed herein are moisture curable. In other words, the adhesive compositions can be cured by exposure to water, e.g., water vapor, to form a cured product. Ambient humidity generally is adequate to promote cure the adhesive compositions. The humidity of curing may be adjusted, as is known in the art, to affect the curing for a number of applications. Additionally, a temperature of curing, as is known in the art, may be utilized. The temperature of curing may be adjusted for some applications, e.g., where an increased temperature of curing may expedite the cure, for instance.

[0028] As mentioned, the adhesive compositions disclosed herein advantageously can provide an improved, i.e., greater, tack free time as compared to other one-part compositions, such as 4,4'-diphenylmethane diisocyanate based compositions not including the reaction formed by reacting from 15 to 50 weight percent of the

diphenylmethane diisocyanate component and from 50 to 85 weight percent of a polyol, based upon a total weight of the diphenylmethane diisocyanate component and the polyol and the aliphatic isocyanate, as disclosed herein.

[0029] The cured products formed using the adhesive compositions, such as adhesives and composites, may have one or more desirable mechanical properties, which may be advantageous for a number of applications. If the cured product is a composite, it may include additives in addition to the adhesive composition.

[0030] The cured product may have a tensile strength, as determined by ASTM D638, from a lower limit of 0.30; 0.33; or 0.35 MPa or to an upper limit of 2.0; 1.5; or 1.0 MPa.

[0031] The cured product may have an elongation at break (%), as determined by ASTM D638, from a lower limit of 50; 55; or 60% or to an upper limit of 85; 80; or 75%. Greater elongation at break (%) may be desirable for a number of applications.

[0032] The adhesive compositions may be utilized for a number of applications such as, bonding together materials, e.g., from a composite layer with additives and the adhesive composition via a curing as discussed herein. The materials/additives to be bonded together may have various compositions for different applications, as known in the art. Examples of such materials/additives include, but are not limited to, rubber, foam, copolymers of ethylene and vinyl acetate, cork, gravel, wood, and combinations thereof, among others.

[0033] The material/additive to be bonded together may have different forms for various applications. For instance, the material may be fibers, particles, and

combinations thereof, among others. The material(s) can be substantially spherical, substantially non- spherical, and combinations thereof. Examples of substantially non- spherical shapes include, but are not limited to, cubic shapes, polygonal shapes, elongate shapes, irregular shapes and combinations thereof. Various sizes and/or amounts of the material may be utilized with the adhesive composition for different applications.

[0034] The bonding together of the material/additive may be performed by a molded process, an in-situ process, or a combination thereof. The adhesive composition and the materials may be combined by any suitable know process, e.g., mechanical mixing. As an example, a molded process may be utilized for applications such as forming mats or safety tiles, among other applications; an in-situ process may be utilized for applications such as forming of athletic tracks or playground surfaces, among other applications. [0035] One or more embodiments of the present disclosure provide that the adhesive composition disclosed herein may be combined with a material to form a cured product, i.e., a composite material. As an example, the adhesive composition may be combined with rubber particles, e.g., such that the rubber particles and the cured adhesive together form the cured product. The adhesive composition may be combined with rubber particles by an in-situ process. For this example, the cured product may be referred to as an athletic track and/or a sport track.

[0036] One embodiment of the present disclosure provides that the material to be bonded together is rubber particles having an average diameter from 2 microns to 10 microns. All individual values and subranges from 2 microns to 10 microns are included; for example, the rubber particles can have an average diameter from a lower limit of 2, 2.5, or 3 microns to an upper limit of 10, 7.5, or 5 microns. The rubber particles may be from 5 weight percent to 80 weight percent, based upon a total weight of the adhesive composition and the rubber particles. All individual values and subranges from 5 weight percent to 80 weight percent are included; for example, the rubber particles can be form a lower limit of 5, 8, 10, 12, or 15 weight percent to an upper limit of 80, 70, 60, 50, 40, 30, or 20 weight percent based upon the total weight of the adhesive composition and the rubber particles.

[0037] One or more embodiments of the present disclosure provide that the adhesive composition disclosed herein may be utilized to bond, e.g., via curing described herein, a composite material to another material. The composite material may be formed from the disclosed adhesive composition; however, other composite materials may be utilized. Different composite materials may be utilized for various applications. As an example, an athletic track material, e.g., a material containing rubber particles, may be placed upon a surface such that the adhesive composition is located between the athletic track material and the surface; thereafter, the adhesive composition may be cured to bond the athletic track material and the surface together. The surface may have various compositions for different applications, as known in the art. Further, various amounts of the adhesive composition may be utilized to bond composite material and the surface for different applications.

EXAMPLES [0038] In the Examples, various terms and designations for materials are used including, for instance, the following:

[0039] Diphenylmethane diisocyanate component (4,4'-diphenylmethane diisocyanate, obtained from the Dow Chemical Company); VORANOL™ WD 2130 (polyether polyol; average functionality 2.0; weight average molecular weight 3,000; obtained from the Dow Chemical Company); VORANOL™ 4000LM (polyether polyol; average functionality 2.0; weight average molecular weight 4,000; obtained from the Dow

Chemical Company); VORANOL™ 2000LM (polyether polyol; average functionality 2.0; weight average molecular weight 2,000; obtained from the Dow Chemical

Company); benzyl chloride (quatemizing agent; obtained from Sinopharm Chemical Co.); aliphatic isocyanate (isophorone diisocyanate; average functionality 2.0; obtained from Evonik); aliphatic isocyanate (hexamethylene diisocyanate trimer; average functionality 3.0; obtained from Nippon Polyurethane Industry Co., Ltd); rubber particles (particle size 3 to 5 mm, Nanjing Feeling Rubber &Plastic Products Co., Ltd.).

[0040] Example 1, an adhesive composition, was formed as follows. VORANOL™ WD 2130 was dehydrated at 110 °C and 76 mmHg pressure for approximately one hour and then cooled to room temperature. Diphenylmethane diisocyanate component (31.0 grams) was added to a container (250 mi-three neck flask under nitrogen flow) and heated to 65 °C while stirring to form a reaction product. Benzyl chloride (100 ppm based upon a total weight of the diphenylmethane diisocyanate component and the polyol) was added to the container while stirring; after approximately 5 minutes, dehydrated VORANOL™ WD 2130 (67.0 grams) was added to the container via a constant pressure drop funnel under nitrogen at a rate of 2 grams per minute. The contents of the container were stirred for approximately 30 minutes and then isophorone diisocyanate (2.0 grams) was added to the container to provide Example 1.

[0041] Example 2, an adhesive composition, was formed as Example 1, with the changes that diphenylmethane diisocyanate component (28.8 grams), benzyl chloride (100 ppm based upon a total weight of the diphenylmethane diisocyanate component and the polyol), dehydrated VORANOL™ WD 2130 (67.2 grams), and isophorone diisocyanate (4.0 grams) were utilized. [0042] Example 3, an adhesive composition, was formed as Example 1, with the changes that diphenylmethane diisocyanate component (25.0 grams), benzyl chloride (100 ppm based upon a total weight of the diphenylmethane diisocyanate component and the polyol), dehydrated VORANOL™ 4000LM (73.0 grams) rather than VORANOL™ WD 2130, and isophorone diisocyanate (2.0 grams) were utilized.

[0043] Example 4, an adhesive composition, was formed as Example 1, with the changes that diphenylmethane diisocyanate component (24.5 grams), benzyl chloride (100 ppm based upon a total weight of the diphenylmethane diisocyanate component and the polyol), dehydrated VORANOL™ 4000LM (71.5 grams) rather than VORANOL™ WD 2130, and isophorone diisocyanate (4.0 grams) were utilized.

[0044] Example 5, an adhesive composition, was formed as Example 1, with the changes that diphenylmethane diisocyanate component (25.5 grams), benzyl chloride (100 ppm based upon a total weight of the diphenylmethane diisocyanate component and the polyol), dehydrated VORANOL™ 4000LM (73.0 grams) rather than VORANOL™ WD 2130; additionally, hexamethylene diisocyanate trimer (2.0 grams) was utilized rather than isophorone diisocyanate.

[0045] Example 6, an adhesive composition, was formed as Example 1, with the changes that diphenylmethane diisocyanate component (24.5 grams), benzyl chloride (100 ppm based upon a total weight of the diphenylmethane diisocyanate component and the polyol), dehydrated VORANOL™ 4000LM (71.5 grams) rather than VORANOL™ WD 2130; additionally, hexamethylene diisocyanate trimer (4.0 grams) was utilized rather than isophorone diisocyanate.

[0046] Comparative Example A was formed as Example 1, with the changes that diphenylmethane diisocyanate component (40.0 grams), benzyl chloride (100 ppm based upon a total weight of the diphenylmethane diisocyanate component and the polyol), and VORANOL™ 2000LM (60.0 grams) rather than VORANOL™ WD 2130 were utilized; no aliphatic isocyanate was included in Comparative Example A.

[0047] Comparative Example B was formed as Example 1, with the changes that diphenylmethane diisocyanate component (30.0 grams), benzyl chloride (100 ppm based upon a total weight of the diphenylmethane diisocyanate component and the polyol), and VORANOL™ 4000LM (70.0 grams) rather than VORANOL™ WD 2130 were utilized; no aliphatic isocyanate was included in Comparative Example B.

[0048] The compositions of Examples 1-6 are reported in Table 1. The composition of Comparative Examples A-B are reported in Table 2.

Table 1

Table 2

[0049] NCO content (%), viscosity, and tack free time were determined for

Examples 1-6 and Comparative Examples A-B respectively; the results are reported in Table 3. NCO content was determined according to ASTM D5155, viscosity was determined according to ASTM D4889, and tack free time was determined according to ASTOM C679.

[0050] NCO content (weight %) was determined through titration as follows. Toluene and a mixture of dibutylamine (DBA) (155 ml) and N, N - dimethylformamide (DMF) (350 ml) were each dried via sieve for approximately 12 hours.

[0051] A blank test was run by adding dried toluene (6ml), isopropanol (10 ml), and the dried mixture of DBA and DMF (2 ml) to a container and shaking for 10 minutes. Hydrochloric acid (0.5) was utilized to titrate the contents of the container. This was repeated to verify that a volume consumption of hydrochloric acid was less than 0.05 ml.

[0052] For sample testing, the sample to be tested was added to a container and weighed; then dried toluene (6 ml) and the dried mixture of DBA and DMF (2 ml) were added to the container, followed by the addition of isopropanol (10 ml). Hydrochloric acid (0.5) was utilized to titrate the contents of the container.

[0053] NCO content (%) was calculated by the following formula:

[0054] where B is the volume of consumed hydrochloric acid in blank test; S is the volume of consumed hydrochloric acid in sample test; N is the concentration of hydrochloric acid (0.5 M), and W is the weight of sample.

[0055] Viscosity was determined with a TA instrument AR2000ex at 25 °C, utilizing an aluminum plate, continuous flow, and a shear rate of 1-100 s ¹.

[0056] Tack free time was determined by placing a sample into an aluminum plate and then placing the loaded plate into an oven (80 °C, 10% humidity) and was tested in accordance with ASTM C679.

Table 3

[0057] The data of Table 3 illustrates that each of Examples 1-6 had an improved, i.e., greater, tack free time as compared to each of Comparative Example A and Comparative Example B. The data of Table 3 further illustrates that each of Examples 1-6 had a greater viscosity as compared to Comparative Example A, which may be desirable for a number of applications. Each of Examples 1 and 3-6 had a greater viscosity as compared to Comparative Example B, while Example 2 and Comparative Example B had comparable viscosities.

[0058] Example 7, a composite product, was formed by combining Example 1 (35 grams) and rubber particles (245 grams) by mechanical mixing. The combined materials were placed into a mold (20 cm long, 20 cm wide, 1 cm deep) and then into an oven (80 °C, 10% humidity) to cure for approximately 8 hours. Examples 8-12, composite products, were formed as Example 7 with the change that Examples 2-6 were

respectively utilized rather than Example 1. Comparative Example C-D were formed as Example 7 with the change that Comparative Examples A-B were respectively utilized rather than Example 1.

[0059] Tensile strength and elongation at break (%) for Examples 7-12 and

Comparative Examples C-D respectively; the results are reported in Table 4. Tensile strength and elongation at break (%) were determined with a CMT4104 machine; the tensile speed was 500 mm/min.

Table 4

[0060] The data of Table 4 illustrates that each of Examples 7-12 has a similar tensile strength as compared to Comparative Examples C-D. The data of Table 4 further illustrates that each of Examples 7-12 has a greater elongation at break (%) as compared to both Comparative Examples C-D, which may be desirable for a number of applications.

Claims

Claims What is claimed:

1. An adhesive composition comprising:

a reaction product formed by reacting from 15 to 50 weight percent of a diphenyimethane diisocyanate component, which includes from 90 to 100 weight percent of 4,4’-diphenyl ethane diisocyanate based on a total weight of the diphenyimethane diisocyanate component, and from 50 to 85 weight percent of a polyol, based upon a total weight of the diphenyimethane diisocyanate component and the polyol; and

an aliphatic isocyanate, wherein the aliphatic isocyanate is from 0.5 to 20 weight percent based upon a total weight of the 4,4'-diphenylmethane diisocyanate, the polyol, and the aliphatic isocyanate.

2. The adhesive composition of claim 1, wherein the polyol has a weight average molecular weight from 300 to 12,000 g/mol.

3. The adhesive composition of any one of claims 1-2, wherein the polyol has an average functionality from 1.5 to 3.5

4. The adhesive composition of any one of claims 1-3, wherein the aliphatic isocyanate has an average functionality from 1.5 to 3.5.

5. The adhesive composition of any one of claims 1-4, wherein the aliphatic isocyanate is selected from isophorone diisocyanate, isophorone diisocyanate trimer, hexamethylene diisocyanate trimer, and combinations thereof.

6. The adhesive composition of any one of claims 1-5, wherein the polyol is selected from poly ether polyols, polyester polyols, and combinations thereof.

7. The adhesive composition of any one of claims 1-6, wherein the adhesive composition has an NCO content from 3.0 to 12.0 weight percent, based upon a total weight of the adhesive composition.

8. A composite product formed by curing the adhesive composition of any one of claims 1-7 in the presence of rubber particles.

9. The composite product of claim 8, wherein the composite product is an athletic track.