ADHESIVE COMPOSITION AND RUBBER REINFORCING MATERIAL

Abstract

The present invention relates to an adhesive composition including a latex (A), a polyurethane (B), an amine-based adhesion promoter (C), and a water-containing solvent (G). The composition is eco-friendly, has a low risk of fire, and has excellent adhesive strength.

Claims

1. An adhesive composition comprising a latex (A), a polyurethane (B), an amine-based adhesion promoter (C), and a water-containing solvent (G), wherein a relative viscosity measured at room temperature using an Ubbelohde viscometer satisfies the range of 2.50 to 3.00.

2. The adhesive composition according to claim 1, wherein the amine-based adhesion promoter (C) is a reaction product of a fatty acid (C.sub.1) and an amine compound (C.sub.2).

3. The adhesive composition according to claim 2, wherein the fatty acid (C.sub.1) is a saturated fatty acid having an aliphatic chain having carbon atoms in the range of 6 to 30.

4. The adhesive composition according to claim 2, wherein the amine compound (C.sub.2) is an alkylene diamine having 1 to 12 carbon atoms.

5. The adhesive composition according to claim 1, wherein the amine-based adhesion promoter (C) is represented by the following Chemical Formula 1. ##STR00002## wherein, in Chemical Formula 1, R.sub.1 and R.sub.2 are each independently a substituted or unsubstituted aliphatic chain group having carbon atoms in the range of 6 to 30, and A is a divalent group having carbon atoms in the range of 1 to 12.

6. The adhesive composition according to claim 1, which further comprises an amine-based chain extender (D).

7. The adhesive composition according to claim 6, wherein a weight (W.sub.1) of the amine-based adhesion promoter (C) is greater than a weight (W.sub.2) of the an amine-based chain extender (D).

8. The adhesive composition according to claim 7, wherein a weight ratio (W.sub.1/W.sub.2) between the weight (W.sub.1) of the amine-based adhesion promoter (C) and the weight (W.sub.2) of the amine-based chain extender (D) is in the range of 1.5 to 10.

9. The adhesive composition according to claim 6, wherein the composition contains 1.0% by weight or more of the amine-based adhesion promoter (C) based on the total weight of the composition.

10. The adhesive composition according to claim 1, Wherein the composition contains 40% by weight or more of water based on the total weight of the composition.

11. The adhesive composition according to claim 1, wherein the composition contains 1.0 to 30% by weight of the latex (A) based on the total weight of the composition.

12. The adhesive composition according to claim 1, wherein the polyurethane (B) comprises a polyurethane having a weight average molecular weight (Mw) in the range of 250,000 to 350,000.

13. The adhesive composition according to claim 12, wherein the composition contains 0.5 to 9.0% by weight of the polyurethane based on the total weight of the composition.

14. The adhesive composition according to claim 1, wherein the composition further comprises an epoxy compound (E).

15. The adhesive composition according to claim 1, wherein the composition further comprises an isocyanate compound (F).

16. A rubber reinforcing material comprising a raw cord containing fibers; and a coating layer formed on the raw cord, wherein the coating layer is formed from the adhesive composition according to claim 1.

17. The rubber reinforcing material according to claim 16, wherein the raw cord is a hybrid cord formed by secondarily twisting two different types of primarily twisted yarns.

18. The rubber reinforcing material according to claim 17, wherein the hybrid cord comprises a primarily twisted aramid yarn and a primarily twisted nylon yarn.

19. The rubber reinforcing material according to claim 16, the rubber reinforcing material sequentially comprises a raw cord; a first coating layer formed on the raw cord; and a second coating layer formed on the first coating layer and formed from the adhesive composition according to claim 1, wherein the first coating layer comprises at least one compound selected from epoxy and isocyanate as a reaction-active group imparting component.

20. A rubber composite comprising the rubber reinforcing material according to claim 16.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0152] FIG. 1 schematically shows an Ubbelohde viscometer in order to explain a method for measuring the relative viscosity of the adhesive composition of the present invention.

[0153] FIG. 2 schematically shows a cross-section of a tire cord that can be manufactured using the adhesive composition according to an embodiment of the present invention.

[0154] FIG. 3 schematically shows the process of manufacturing the tire cord.

[0155] FIG. 4 schematically shows a cross section of a tire that can be manufactured using an adhesive composition according to an embodiment of the present invention.

REFERENCE NUMERALS

[0156] 10: raw cord [0157] 11: primarily twisted yarn [0158] 12: primarily twisted yarn [0159] 20: coating layer [0160] 21: first coating layer [0161] 21′: first coating liquid [0162] 22: second coating layer [0163] 22′: second coating liquid [0164] 30: tire cord [0165] 100: first winder [0166] 200: first coating tank [0167] 300: first drying device [0168] 400: second coating tank [0169] 500: second drying device [0170] 600: second winder [0171] 1000: tread [0172] 2000: shoulder [0173] 3000: sidewall [0174] 4000: cap ply [0175] 5000: belt [0176] 6000: body ply or carcass [0177] 7000: inner liner [0178] 8000: apex [0179] 9000: bead

Detailed Description of the Embodiments

[0180] Hereinafter, the action and effect of the invention will be described in more detail with reference to specific examples of the invention. However, these examples are presented for illustrative purposes only, and the scope of the invention is not limited thereto in any sense.

PREPARATION EXAMPLE

Preparation Example 1: Preparation of Polyurethane Dispersion in Water

[0181] Polyester-based polyol (weight average molecular weight: about 2,000), diol (1,6-hexane diol), and ionomer (DMBA: dimethylol butanoic acid) were charged into a reactor, and then the mixture was stirred at 75±5° C. for 4 hours. Then, an aliphatic isocyanate dicyclohexymethane-4,4′-diisocyanate) was reacted for 2 hours to prepare a prepolymer. The reaction temperature of the prepared prepolymer was lowered to 60° C., and then a neutralizing agent (TEA: triethanolamine) was added to a solvent to perform neutralization. At this time, a stirrer was used for dispersion, and the dispersion was performed while maintaining the RPM of the stirrer at 1,000 to 1,500. After the dispersion was completed, the solvent (acetone) was removed from the prepolymer through reduced pressure. Then, distilled water was added to the neutralized prepolymer so that the solid content was 60 wt. %, and the mixture was stirred to perform water dispersion. Finally, a chain extender (EDA: ethylene diamine) was added thereto to prepare a polyurethane dispersion in water having a weight average molecular weight of about 308,000.

Preparation Example 2: Preparation of the Compositions of Examples and Comparative Examples

[0182] Mixing and stirring were performed under the same conditions with the content (wt. %) as in shown Table 1 below, to prepare the compositions of Examples and Comparative Examples. Specifically, each component was mixed and stirred at about 20° C. for 24 hours.

TABLE-US-00001 TABLE 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 (A) Latex 14.7 13.7 12.7 11.7 14.7 14.7 14.7 14.7 14.7 (B) Polyurethane 1.8 1.8 1.8 1.8 0.8 2.8 3.8 1.8 1.8 dispersion in water (C) Amine-based 1.8 1.8 1.8 1.8 1.8 1.8 1.8 2.8 3.8 adhesion promoter (D) Amine-based 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.6 0.85 chain extender (E) Epoxy compound 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 (F) Isocyanate 3.7 3.7 3.7 3.7 3.7 3.7 3.7 3.7 3.7 (G) Solvent Total 76.4 77.4 78.4 79.4 77.4 75.4 74.4 75.2 73.95 content Water (pure 46.8 49.2 51.7 54.2 48.4 45.1 43.4 43.7 40.7 water) Unit (content): each wt. % of solid content components (A) to (F), and wt. % of solvent (G) which is non-solid content (A) Latex: VP latex, 0653 from Closlen (B) Polyurethane dispersion in water: Polyurethane dispersion in water prepared in Preparation Example 1 was used (C) Amine-based adhesion promoter (primary amine compound): N,N′-ethylenebis (stearamide), a reaction product of ethylenediamine and stearic acid (D) Amine-based chain extender (secondary amine compound): piperazine (E) Epoxy compound: EX614B from NAGASE with equivalent weights adjusted to the range of 120 to 300 g/eq (F) Isocyanate: IL-6 from EMS (G) Solvent: Non-solid content component containing pure water (demineralized water)

TABLE-US-00002 TABLE 2 Comparative Comparative Comparative Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 (A) Latex 0 32 14.7 14.7 14.7 14.7 (B) Polyurethane 1.8 1.8 0.2 10 1.8 4.5 dispersion in water (C) Amine-based 1.8 1.8 1.8 1.8 0.5 6 adhesion promoter (D) Amine-based 0.4 0.4 0.4 0.4 0.4 0.4 chain extender (E) Epoxy compound 1.2 1.2 1.2 1.2 1.2 1.7 (F) Isocyanate 3.7 3.7 3.7 3.7 3.7 3.4 (G) Solvent Total 91.1 59.1 78 68.2 77.7 69.3 content Water (pure 83.1 4.1 49.5 33.1 50.7 29.6 water) Unit (content): each wt. % of solid content components (A) to (F), and wt. % of solvent (G) which is non-solid content (A) Latex: VP latex, 0653 from Closlen (B) Polyurethane dispersion in water: Polyurethane dispersion in water prepared in Preparation Example 1 was used (C) Amine-based adhesion promoter (primary amine compound): N,N′-ethylenebis (stearamide), a reaction product of ethylenediamine and stearic acid (D) Amine-based chain extender (secondary amine compound): piperazine (E) Epoxy compound: EX614B from NAGASE with equivalent weights adjusted to the range of 120 to 300 g/eq (F) Isocyanate: IL-6 from EMS (G) Solvent: Non-solid content component containing pure water (demineralized water)

[0183] Preparation Example 3: Manufacture of raw cord and tire cord Aramid yarn (1,500 de) and nylon yarn (1,260 de) were used to prepare two strands (11, 12) of primarily twisted yarns (Z-direction) having a number of twists of 360 TPM, and then the two strands of primarily twisted yarns were secondarily twisted together (S-direction) with a number of twists of 360 TPM to manufacture a plied yarn (1,500 de A/1,260 de N). The plied yarn thus manufactured was used as a raw cord 10.

[0184] A coating layer 20 was formed on the raw cord 10 to manufacture a tire cord 30. Specifically, a raw cord composed of aramid and nylon was dipped in the first coating liquid, and then treated at a drying temperature of 150° C. and a curing temperature of 240° C. for about 1 minute, respectively, to form the first coating layer 21, thereby imparting a reaction-active group to the raw cord. At this time, the first coating liquid was prepared by mixing an epoxy compound and an isocyanate compound, which are a part of the components used in Preparation Example 2, in a weight ratio of about 1:2, together with 97 wt. % of demineralized water.

[0185] Then, the adhesive compositions of Examples and Comparative Examples prepared according to Preparation Example 2 (hereinafter, referred to as a “second coating liquid”) were applied to the raw cord having the first coating layer formed thereon. Specifically, the raw cord on which the first coating layer was formed was dipped in the second coating liquid, dried and cured to form a second coating layer 22. At this time, the resulting second coating layer was treated at a drying temperature of 150° C. and a curing temperature of 235° C. for about 1 minute, respectively, to perform the drying and curing. The first coating liquid dipping step and the second coating liquid dipping step were continuously performed, and the tension condition at this time was 0.5 g/d. Through the above process, a tire cord 30 was manufactured in the form of a dipped cord.

EXPERIMENTAL EXAMPLE

Experimental Example 1: Measurement of the Relative Viscosity of the Compositions of Examples and Comparative Examples

[0186] The viscosity of each composition prepared in Preparation Example 2 was measured using an Ubbelohde viscometer after being left in a constant temperature water tank (about 25° C.) for 30 minutes. Specifically, through the following process, a certain amount of demineralized water was put into the Ubbelohde viscometer, and then the viscosity properties of the demineralized water were measured. The viscosity properties of the composition were measured in the same way, and then the relative viscosity was calculated based on the viscosity properties of demineralized water that was already measured. The results are as shown in Table 2 below.

[0187] The viscosity measurement process will be described below with reference to FIG. 1.

[0188] (1) A sample (composition or demineralized water) was injected into an Ubbelohde viscometer tube A.

[0189] (2) The constant temperature water tank was set to 25° C., fixed so that part C was immersed in the water tank, and allowed to stand for 30 minutes.

[0190] (3) The sample was set so as to come up to the middle of part C using a pipette filler.

[0191] (4) After that, the sample was allowed to flow downward, and the time required for the liquid level of the sample to pass through the upper scale of B and then through the lower scale of B was measured.

[0192] (5) The measured time was applied to the following Equation for calculating the relative viscosity, thereby determining the relative viscosity.

[0193] <Equation for Calculating Relative Viscosity>

Relative Viscosity=T.sub.1/T.sub.0

[0194] (T.sub.1: the time required for the adhesive composition to pass through the upper scale of B and then through the lower scale of B, T.sub.0: the time required for demineralized water to pass through the upper scale of B and then through the lower scale of B)

TABLE-US-00003 TABLE 3 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Viscosity (RV) 2.71 2.68 2.64 2.58 2.67 2.73 2.77 2.72 2.73

TABLE-US-00004 TABLE 4 Comparative Comparative Comparative Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Viscosity (RV) 1.84 4.68 2.43 3.21 2.24 3.14

Experimental Example 2: Confirmation of the Degree of Resin Pick Up

[0195] The raw cord manufactured in Preparation Example 3 was dipped in the adhesives (compositions) of Examples and Comparative Examples prepared in Preparation Example 2 for 20 seconds, then rolled up and dried. Specifically, using a tensile tester, the raw cord was dipped in an adhesive solution at a constant speed (about 250 mm/min) and wound up therefrom. Then, the wound raw cord was dried in an oven at 240° C. for 1 minute and 30 seconds.

[0196] The degree (or ratio) of resin pick up (RPU, %) was calculated as shown in [Equation 1] below, and the results are shown in Table 3 below.

{(W.sub.b−W.sub.a)/W.sub.a}×100  [Equation 1]

[0197] wherein, in Equation 1, W.sub.b is the weight (g) of the raw cord after dipping, and W.sub.a is the weight (g) of the raw cord before dipping.

TABLE-US-00005 TABLE 5 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 RPU (%) 4.9 4.7 4.5 4.2 4.8 5.2 5.5 5.2 5.4

TABLE-US-00006 TABLE 6 Comparative Comparative Comparative Comparative Comparative Comparative Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 RPU (%) 2.2 8.7 3.8 6.5 3.2 6.8

[0198] As shown in Tables 3 and 4 above, it can be confirmed that the adhesive compositions of Comparative Example 1, Comparative Example 3, and Comparative Example 5 have lower viscosity and higher flowability than those of Examples. When the flowability is excessively high, the resin pick up is low as shown in Table 6. Therefore, the coating layer may not be uniformly formed on the adherend or the surface to be coated, and may not provide sufficient adhesive strength. The comparison results of the adhesive strength using the compositions of Examples and Comparative Examples can be confirmed in Tables 8 and 9 below.

[0199] In addition, as shown in Tables 3 and 4, it can be confirmed that the adhesive compositions of Comparative Example 2, Comparative Example 4, and Comparative Example 6 have higher viscosity and lower flowability than those of Examples. If the flowability is excessively low, sufficient mixing between components of the composition is not performed and thus, the adhesive strength may be reduced. The comparison results of the adhesive strength using the compositions of Examples and Comparative Examples can be confirmed in Tables 8 and 9 below.

Experimental Example 3: Evaluation of Adhesive Strength

[0200] The adhesive strength per unit area to the tire cord manufactured in Preparation Example 3 was evaluated using the compositions of Examples and Comparative Examples, respectively. The evaluation of the adhesive strength was performed by a method of measuring the adhesive peel strength of the tire cord in according with ASTM D4393.

[0201] Specifically, a 0.6 mm thick rubber sheet, a cord paper (tire cord of Preparation Example 3), a 0.6 mm thick rubber sheet, a cord paper (tire cord of Preparation Example 3), and a 0.6 mm thick rubber sheet were sequentially laminated, and vulcanized at 170° C. for 15 minutes under a pressure of 60 kg/cm′ to manufacture a sample. Then, the sample was cut to prepare a test specimen having a width of 1 inch. For reference, the rubber sheet has the composition shown in Table 7 below, and is a sheet used for the carcass constituting a tire. By using a laminate using such a rubber sheet, he adhesive strength of the tire cord to the carcass layer can be confirmed.

[0202] For the prepared test specimen, a peel test was performed at 25° C. at a rate of 125 mm/min using a universal testing machine (Instron), and the adhesive strength of the tire cord to the carcass layer was measured. The relative magnitude of the measured adhesive strength is shown in Tables 8 and 9 below. At this time, the average value of three time measurements of the loads generated at the time of peeling was calculated as the adhesive strength.

TABLE-US-00007 TABLE 7 Content (weight ratio based on 100 weight Rubber sheet component parts of natural rubber) Natural rubber 100 Zinc oxide 3 Carbon black 29.8 Stearic acid 2.0 Pine tar 7.0 Mercaptobenzothiazole 1.25 Sulfur 3.0 Diphenylguanidine 0.15 Phenylbetanaphthalamine 1.0

TABLE-US-00008 TABLE 8 Example 10 Example 11 Example 12 Example 13 Example 14 Example 15 Example 16 Example 17 Example 19 Adhesive Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 composition used Adhesive 100 97 96 96 95 98 100 99 100 strength (%) * Adhesive composition used: refers to the adhesive composition used at the time of forming the second coating layer * Adhesive strength: the results of Example 10 are relatively compared based on 100%

TABLE-US-00009 TABLE 9 Comparative Comparative Comparative Comparative Comparative Comparative Example 7 Example 8 Example 9 Example 10 Example 11 Example 12 Adhesive Comparative Comparative Comparative Comparative Comparative Comparative composition used Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Adhesive 54 72 81 82 85 79 strength (%) * Adhesive composition used: refers to the adhesive composition used at the time of forming the second coating layer * Adhesive strength: the results of Example 10 are relatively compared based on 100%