WO1992008764A1

WO1992008764A1 - Elastomeric composition

Info

Publication number: WO1992008764A1
Application number: PCT/US1991/008392
Authority: WO
Inventors: Richard Anthony Miller
Original assignee: Eastman Kodak Company
Priority date: 1990-11-16
Filing date: 1991-11-15
Publication date: 1992-05-29

Abstract

An elastomer composition is prepared containing an amorphous propylene copolymer selected from propylene butene and propylene hexene copolymers and an elastomer selected from butyl elastomers, crosslinked butyl elastomers, and styrene ethylene butadiene styrene block copolymers.

Description

ELASTOMERIC COMPOSITION

This invention relates to elastomeric compositions used in hot—melt formulations that contain an elastomer and an amorphous propylene copolymer.

Background of the Invention

Elastomeric compositions are well known and have been used in the industry for various applications such as adhesives, caulks, and sealants. These compositions typically contain an elastomer, a resin, and optionally a filler. The most costly component of these compositions is the elastomer. Therefore, compositions containing reduced amounts of elastomer to produce lower cost formulations would be very desirable and have been attempted in the industry. These lower cost formulations containing lower amounts of elastomer typically have increased filler loading or additional polymers such as low molecular weight polybutenes. However, these lower cost formulations typically have lower performance illustrated by low peel adhesion, tensile strength and/or poor weathering performance.

It would, therefore, be very desirable to produce low cost elastomeric formulations containing reduced amounts of elastomer while retaining the performance of formulations containing the high amounts of elastomer. Summary of the Invention The present invention is directed to unique compositions containing an elastomer and an amorphous propylene copolymer selected from propylene/butene copolymers, and propylene/hexene copolymers. These compositions are useful in adhesive, caulk and sealant formulations and contain a reduced amount of elastomer while maintaining good performance. These compositions comprise: (a) about 10 to 90 wt. %, based on (a) plus (b) , of an amorphous propylene copolymer selected from copolymers of propylene/butene, propylene/hexene, and mixtures thereof, containing about 30 to 80 wt. % butene or hexene and about 70 to 20 wt. % propylene;

(b) about 10 to 90 wt. %, based on (a) plus (b) , of an elastomer selected from butyl elastomers, crosslinked butyl elastomers, styrene ethylene butadiene styrene block copolymers, and mixtures thereof; and optionally contains up to about 70 wt. % of a tackifier and up to about 80 wt. % of a filler. The amorphous propylene copolymer extends the elastomer, partially replacing the elastomer in the formulations while retaining and or improving performance properties such as enhanced peel adhesion and structural strength. Detailed Description of the Invention The composition of the present invention comprises: (a) about 10 to 90 wt. %, based on (a) plus (b) , of an amorphous propylene copolymer selected from copolymers of propylene/butene, propylene/hexene, and mixtures thereof, containing about 30 to 80 wt. % butene or hexene and about 70 to 20 wt. % propylene; (b) about 10 to 90 wt. %, based on (a) plus (b) , of an elastomer selected from butyl elastomers, crosslinked butyl elastomers, styrene ethylene butadiene styrene block copolymers, and mixtures thereof; (c) about 0 to 70 wt. %, based on the total weight, of a tackifier, and; (d) about 0 to 80 wt. %, based on the total weight, of a filler. The applicant has unexpectedly discovered that the amorphous copolymers of propylene/butene or propylene/hexene can be used as an elastomeric extender in various compositions, while retaining good performance properties. The compositions of the present invention are particularly useful in caulk and sealant formulations typically containing an elastomer, a resin, and filler.

The amorphous copolymers of propylene/butene and propylene/hexene are known and are generally prepared by anionic coordination polymerization. They are made in solution or in the melt phase at 160—200°C. These amorphous propylene copolymers are illustrated in the following U.S. patents 3,923,758, 4,826,939, 3,954,697, 4,072,813, and 4,259,470. The disclosures of which are incorporated herein in their entirety by reference. These amorphous propylene copolymers preferably contain between about 40 and 70 wt. % butene or hexene. More_.preferably between about 45 and 55 wt. % butene or 40 and 50 wt. % hexene. The amorphous propylene copolymers can also be a propylene/butene/hexene terpolymers or contain minor amounts of monomers other than the butene or hexene. This third monomer is preferably present in a concentration that is no more than about 20% by weight. Should the propylene copolymers contain a third monomer the amount of this third monomer is preferably between about .5 and 10% by weight. This third monomer is preferably ethylene.

The amorphous propylene copolymers are preferably maleated amorphous propylene copolymers preferably having an acid number between about 23 and 44. These maleated amorphous propylene copolymers are well known in the art and are prepared by graft polymerization as illustrated in U. S. 4,567,223 the disclosure of which is incorporated in its entirety herein by reference. The maleated amorphous propylene copolymers more preferably have an acid number between about 20 and 23. This aspect is disclosed and claimed more broadly in an application by the same inventor filed the same day as the present application.

The composition according to the present invention preferably contains about 25 to 75 wt. % amorphous propylene copolymer based on a total of copolymer and elastomer. More preferably the composition contains between about 40 and 60 wt. % amorphous propylene copolymer with about 50 wt. % amorphous propylene copolymer being most preferred.

The composition according to the present invention, when used as a hot—melt adhesive formulation, preferably contains about 20 to 70 wt. % tackifier more preferably about 40 to 60 wt. %.

The composition of the present invention, when used as a caulk or sealant, preferably contains about 5 to 30 wt.. % tackifier, and about 20 to 60 wt. % filler. More preferably the caulk or sealant composition contains about 10 to 20 wt. % tackifier and about 20 to 30 wt. % filler.

The tackifier used in the composition of the present invention is preferably selected from at least one of the groups consisting of hydrocarbon resins, synthetic polyterpenes, and rosin esters. The tackifier preferably has a ring and ball softening point of about 95 to 135°C. Suitable resins and rosin esters are the terpene polymers having the suitable ring and ball softening point such as the polymeric, resinous materials including the dimers as well as higher polymers obtained by polymerization and/or copolymerization of terpene hydrocarbons such as the alicyclic, monocyclic, and bicyclic monoterpenes and their mixtures, including allo—ocimene, carene, isomerized pinene, pinene, dipentene, terpinene, terpinolene, limonene, turpentine, a terpene cut or fraction, and various other terpenes. Particularly useful starting materials are terpene mixtures containing a mixture of sulphate terpene, and at least 20% of at least one other terpene selected from the group consisting of pinene, limonene, or dipentene.

The more preferred tackifying resins are selected from hydrocarbon resins such as disclosed in U.S.

3,850,858 the disclosure of which is incorporated in its entirety herein by reference. These hydrocarbon resins preferably have a ring and ball softening point of about 100 to 130°C, an acid number of about 0 to 2 an acid value of less than about 1 and an iodine value of 75 to 100. These hydrocarbon tackifying resins can be prepared by the polymerization of monomers consisting primarily of olefins and diolefins and include, for example, the residual by—product monomers resulting from the manufacture of isoprene.

Fillers suitable for use in the present invention are, for example, finely divided fume silica, calcium carbonate, titanium dioxide, zinc dioxide, graphite, clay, talc, other metal oxides, and the like. Such fillers have a particle size not much greater than 20 microns preferably between about 5 and 10 microns and are preferably selected from calcium carbonate, titanium dioxide, and zinc dioxide.

The elastomer used in the elastomeric composition of the present invention is selected from butyl elastomers, at least partially crosslinked butyl elastomers, styrene, ethylene/butadiene/styrene block copolymers and mixtures thereof. These elastomers are generally known and are prepared commercially. Elastomers are more preferably selected from butyl elastomers at least partially crosslinked with divinyl benzene and butyl elastomers having unsaturated isoprene and isobutylene units. Suitable elastomers for example include KALAR 5214 a partially crosslinked butyl elastomer from Hardman Chemical Company and EXXON 268 a crosslinked butyl elastomer from Exxon Chemical Company.

Antioxidants can also be added to the adhesive composition of the present invention. Examples of effective antioxidants include, tris(di—t—butyl—p- hydroxybenzyl)—trimethylbenzene (available as Ionox 330 from Shell Chemical) , alkylated bisphenol (available as Naugawhite from Uniroyal) , zinc dibutyl dithiocarbamate (available as Butyl Zimate from R. T. Vanderbilt) , and 4,4'—methylene bis(2,6-di—tert—butylphenol) (Ethyl 702) , tetrakis[methylene(3,5—di-tert—buty1-4— hydroxyhydroinnamate)methane] (available as Irganox 1010 from Ciba Geigy) , lauryl stearyl thiodipropionate (Plastanox 1212), and dilauryl 3,3'—thiodipropionate (Plastanox LTDP) , and 2,6-di-tert—butyl-p—cresol (BHT) . The following examples are presented to further illustrate the present invention and are not intended to limit the reasonable scope thereof.

EXAMPLES The following test procedures were used to determine properties.

Test specimens for determining elevated temperature and elevated temperature shear strengths were prepared and tested according to shear strength — ASTM D—1002. Structural strength was determined from peel and tensile strength according to peel strength — ASTM D— 1876 and tensile strength — ASTM D-638.

Acid number, expressed as milligrams of potassium hydroxide required to neutralize one gram of sample was determined in hot toluene using phenolthaline as indicator.

The examples illustrate the improvements in structure strength of a sealant by substituting a copolymer according to the present invention for a portion of elastomer. Blends were made using a Sigma Blade Mixer at a temperature of 350°F and compounding for a minimum of 2 hours. The only variables were the amount of elastomer and copolymer. The composition and results of the improvement in tensile strength, structured strength, or peel adhesion are listed in the following tables. Example l This examples illustrates improvements in tensile strength of a sealant by substituting a propylene copolymer of the present invention for a portion of the elastomer. The only variance were the amount of elastomer and copolymer. The results in improvement in tensile strength are illustrated in the table below.

Table 1

Formulation

Cross—linked butyl

elastomer,^(ϊ) Styrene—ethylene—butadiene 10.0 10.0 10.0 styrene block copolymer (30/70 styrene/rubber) Hydrocarbon Resin** Polybutene, Indopol H—300

(average MW of 1290 *y Calcium Carbonate Antioxidant, Irganox 1010 Amorphous Propylene—butene

copolymer (30% propylene 70% butene) Amorphous Terpolymer of 5.0 propylene—ethylene—butene (69% propylene 6% ethylene 25% butene)

Tensile Strength 134 psi 180 psi 147 psi (924 Km m³(1241.1) (1014)

ASTM D-638 ^w(Kalar 5214 obtained from Hardman Chemical Co.)

(ML1T3 § 260°F) of 50 to 60 ^DAC—B hydrocarbon resin having a softening point of 130°C and available commercially as EASTOTAC H—130E from Eastman Chemical Company

Example 2 The following example illustrates the preparation of a control elastomeric composition.

Table 2 Testing Formulation

Cross-linked butyl elastomer 35 Percent

Calcium Carbonate 30 Percent

Stearic Acid .5 Percent

Irganox 1010 Antioxidant .5 Percent

Polybutene H—100 34 Percent This formulation was compounded in a double arm jacketed mixer at 350°F for two hours. The formulation was then tested by peel adhesion, using a standard peel adhesion testing method commonly incorporated in the trade. The peel adhesions were prepared by applying a 20 mil film of the above sealant to an aluminum, cold roll steel, galvanized and glass substrates. The specimens were tested after standing for 24—hours at room temperature and then after water immersion for 21— ays at room temperature. The samples were tested on an Instron tester typically used in the sealant trade. This above formulation was then incorporated as a control in further testing and is indicated by A in Table 3 below. Example 3 The formulations below were prepared and tested as above in Example 2 with the variations listed in the table. Table 3 below illustrates that the addition of an amorphous propylene—butene copolymer to an elastomeric composition, particularly the maleated copolymer, does not lower the properties and, in fact, enhances the peel strength of this sealant or caulk formulation, particularly the higher acid number maleated propylene—butene copolymer. All peel adhesion failures were cohesive.

Table 3

Testing Formulation: Percent/Weight A B C D

Cross—linked butyl elastomer 35.0 17.5 17.5 17.5

Calcium Carbonate 30.0 30.0 30.0 30.0

Stearic Acid .5 .5 .5 .5

Irganox 1010 antioxidant .5 .5 .5 .5 Polybutene H-100 34.0 34.0 34.0 34.0

Amorphous P/B* 17.5 —

Maleated Amorphous P/B* — 17.5 (Acid number 40)

Maleated Amorphous P/B* — — 17.5 (Acid number of 21)

*P/B = propylene—butene copolymer containing 30% propylene and 70% butene

Test Results Initial Peel Adhesion (PLi) pounds per linear inch (grams/cm)

Substrates A B C D Aluminum 12 5 32 21

(2148) (895) (5728) (3759)

Cold Roll Steel 30 20 (5370) (3580)

Galvanized 9 15 33 20

(1611) (2685) (5907) (3580)

Glass 12 13 37 26

(2148) (2327) (6623) (4654)

Peel Adhesion After 21 Day Water Immersion (Pli) (grams/cm)

Aluminum 13 14 41 23

(2327) (2506) (7339) (4117)

Cold Roll Steel 39 31

Galvanized

Glass

Example 4 The formulations below were prepared and tested as above in Example 2 with the variations listed in the table. Table 4 below illustrates that the addition of a maleated terpolymer to an elastomeric composition does not lower the properties and in fact enhances the peel strength of the elastomeric composition over an unextended standard. All peel adhesion failures were cohesive. Table 4 Testing Formulation Percent/Weight

STD Cross—linked butyl elastomer 35.0 17.5 17.5 17.5 Calcium carbonate 30.0 30.0 30.0 30.0

Stearic Acid .5 .5 .5 .5

Irganox 1010 antioxidant .5 .5 .5 .5 Polybutene H-100 34.0 34.0 34.0 34.0

Maleated Amorphous P/E/B** 17.5 (Acid #22)

Maleated Amorphous 17.5

(Acid #20)

Maleated Amorphous P/E/B* 17.5

(Acid #39) *P/E/B = Propylene—ethylene—butene terpolymer containing

69% propylene, 6% ethylene, and 25% butene. **P/E/B = Propylene—ethylene—butene containing 53% propylene, 2% ethylene and 45% butene.

Peel Adhesion After

21 Day Water Immersion (PLi)

Average of 5 Tests (grams/cm)

Aluminum 13 29 32 34 (2327) (5191) (5728) (6086)

Cold Roll Steel 37 34 30

(6623) (6036) (5370)

Galvanized 9 52 31 37

(1611) (9308) (5549) (6623)

Glass 13 37 39 38

(2727) (6623) (6981) (6802)

Example 5 The formulations below were prepared and tested as above in Example 2 with the variations listed in the table. Table 5 below illustrates that the addition of maleated propylene—ethylene copolymer, particularly the higher acid number of 43, does not lower the properties and in fact enhances the peel adhesion of the elastomeric composition, both initial and after 21—day water immersion over an unextended standard and nonmaleated amorphous polyolefin propylene—ethylene copolymer. The non—maleated amorphous copolymer was also better than the standard. All peel adhesion failures were cohesive.

TABLE 5

Testing Formulation: Percent/Weight

STD Cross—linked butyl elastomer 35.0 17.5 17.5 17.5

Calcium carbonate 30.0 30.0 30.0 30.0

Stearic acid .5 .5 .5 .5

Irganox 1010 Antioxidant .5 .5 .5 .5

Polybutene H—100 34.0 34.0 34.0 34.0 Amorphous P/E* 17.5 Maleated Amorphous P/E* 17.5

(Acid #43)

Maleated Amorphous P/E* 17.5

(Acid #23) *P/E = Propylene—ethylene copolymer containing 87% propylene and 13% ethylene.

Initial Peel Adhesion (PLi) ■ Average of 5 Tests (grams/cm) STD

Aluminum 12 14 15 12

(2148) (2506) (2685) (2148) Cold Roll Steel 21 7

(3759) (1253) Galvanized 9 17 18 14

(1611) (3043) (3222) (2506) Glass 12 16 21 11

(2148) (2864) (3759) (1969)

Peel Adhesion After

21 Day Water Immersion (PLi) Average of 5 Tests (grams/cm)

STD

Aluminum 12 8.4 20 20 (2148) (1432) (3580) (3580)

Cold Roll Steel 33 18

(5907) (3222)

Galvanized 9 18 20 18

(1611) (3222) (3580) ^"(3222) Glass 12 14 12 17

(2148) (2506) (2148) (3043)

Example 6 The formulations below were prepared and tested as above in Example 2 with the variations listed in the table. Table 6 below illustrates that the addition of maleated amorphous propylene—hexene copolymer to an elastomeric composition does not lower the properties and in fact enhances the peel strength of the elastomeric composition, both initial and after 21 day water immersion, over an unextended standard and a nonmaleated amorphous propylene—hexene copolymer containing sealant formulation. The amorphous propylene—hexene copolymer extended the elastomer and did not significantly reduce the properties of the elastomeric composition, particularly for the initial peel adhesion. All peel adhesion failures were cohesive.

Table 6

Initial Peel Adhesion (PLi) Average of 5 Tests (grams/cm) STD

Aluminum 12 9 21 24 16 11 (2148) (1611) (3759) (4296) (2864) (1969)

Cold Roll Steel 25 21 16 21

(4475) (3759) (2864) (3759)

Galvanized 9 10 29 21 20 22

(1611) (1790) (5191) (3759) (3580) (3938) Glass 12 13 21 23 22 23

(2148) (2327) (3759) (4117) (3938) (4117)

Peel Adhesion After 21 Day Water Immersion (PLi) Average of 5 Tests (grams/cm) STD

Aluminum 13 3 18 25 32 24 (2327) (537) (3222) (4475) (5728) (4296)

Cold Roll Steel 31 29 36 32 (5549) (5191) (6444) (5728)

Galvanized 9 3 28 18 29 26 (1611) (537) (5012) (3222) (5191) (4654)

Glass 13 13 27 32 19

(2327) (2327) (4833) (5728) (3401)

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

Claims

CLAIMS We claim:

. 1. A composition comprising: (a) about 10 to 90 wt. %, based on (a) plus (b) , of an amorphous propylene copolymer selected from copolymers of propylene/butene, propylene/hexene, and mixtures thereof, containing about 30 to 80 wt. % butene or hexene and about 70 to 20 wt. % propylene; (b) about 10 to 90 wt. %, based on (a) plus (b) , of an elastomer selected from butyl elastomers, crosslinked butyl elastomers, styrene ethylene butadiene styrene block copolymers, and mixtures thereof; (c) about 0 to 70 wt. %, based on the total weight, of a tackifier, and; (d) about 0 to 80 wt. %, based on the total weight, of a filler.

2. The composition according to Claim 1 wherein said amorphous propylene copolymer is present in the composition in an amount between about 25 to 75 wt. % based on (a) plus (b) .

3. The composition according to Claim 2 wherein said amorphous propylene copolymer is present in an ' amount between about 40 to 60 wt. % based on (a) plus

(b) and contains about 40 to 70 wt. % butene or hexene .

4. The composition according to Claim 3 wherein said amorphous propylene copolymer is present in an amount at about 50 wt. % based on (a) plus (b) .

5. The composition according to Claim 3 wherein said amorphous propylene copolymer contains about 45 to 55 wt. % butene or about 40 to 50 wt. % hexene.

6. The composition according to Claim 1 wherein the elastomer is selected from butyl elastomers having unsaturated isoprene and isobutylene units and butyl elastomer at least partially crosslinked with divinylbenzene.

7. The composition according to Claim 1 comprising about 20 to 70 wt. % tackifier having a softening point between about 100 and 130°C.

8. The composition according to Claim 7 comprising about 40 to 60 wt. % tackifier.

9. The composition according to Claim 1 comprising about 5 to 30 wt. % tackifier having a softening point between about 100 and 130°C.

10. The composition according to Claim 1 comprising about 20 to 60 wt. % filler.

11. The composition according to Claim 10 wherein the filler is selected from the group consisting of calcium carbonate, titanium dioxide, and zinc oxide.