ADHESIVE COMPOSITION, RUBERR REINFORCING MATERIAL AND ARTICLE

Abstract

The present application relates to an adhesive composition including a naturally occurring acid, a nitrogen compound, and a latex; and a rubber reinforcing material and an article including the same.

Claims

1. An adhesive composition comprising a naturally occurring acid, a nitrogen compound, and a latex, wherein a relative viscosity measured at room temperature using an Ubbelohde viscometer satisfies the range of 2.30 to 3.00.

2. The adhesive composition according to claim 1, wherein the naturally occurring acid comprises a naturally occurring phenol.

3. The adhesive composition according to claim 1, wherein the naturally occurring acid comprises a naturally occurring tannic acid.

4. The adhesive composition according to claim 1, which contains 5 to 50 parts by weight of the naturally occurring acid based on 100 parts by weight of the latex.

5. The adhesive composition according to claim 1, which contains 1.0% by weight or more of the naturally occurring acid based on 100% by weight of the total content of the composition.

6. The adhesive composition according to claim 1, which contains 0.5 to 25 parts by weight of the nitrogen compound based on 100 parts by weight of the latex.

7. The adhesive composition according to claim 1, which contains 0.5% by weight or more of the nitrogen compound based on 100% by weight of the total content of the composition.

8. The adhesive composition according to claim 1, which further comprises a solvent.

9. The adhesive composition according to claim 8, which contains 35% by weight or more of the solvent based on 100% by weight of the total content of the composition.

10. The adhesive composition according to claim 8, which contains 50% by weight or more of the solvent based on 100% by weight of the total content of the composition.

11. The adhesive composition according to claim 8, wherein the solvent comprises water.

12. A rubber reinforcing material comprising a raw cord containing a fiber; and a coating layer formed on the raw cord, wherein the coating layer comprises the adhesive composition according to claim 1.

13. The rubber reinforcing material according to claim 12, wherein the raw cord comprises at least one selected from the group consisting of a polyester fiber, a nylon fiber, an aramid fiber, a carbon fiber, a polyketone fiber, a cellulose fiber, and a glass fiber.

14. The rubber reinforcing material according to claim 12, wherein: when measured by a color-difference meter, the L* value is 50 to 60, the a* value is 4.5 to 10, and the b* value is 10 to 25.

15. The rubber reinforcing material according to claim 12, wherein the rubber reinforcing material is a tire cord.

16. An article comprising the rubber reinforcing material according to claim 12.

17. A rubber composite according to claim 16, wherein the article is a tire.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0116] 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 application.

[0117] FIG. 2 schematically shows a cross section of a tire cord that can be manufactured by using an adhesive composition according to an exemplary embodiment of the present application.

[0118] FIG. 3 schematically shows a manufacturing process of a tire cord.

[0119] FIG. 4 schematically shows a cross section of a tire that can be manufactured by using an adhesive composition according to an exemplary embodiment of the present application.

[0120] FIG. 5 schematically shows the appearance of a sample for color difference measurement. Specifically, FIG. 5a is an exemplary embodiment of one specimen (S1 or S2), and FIG. 5b schematically shows a state in which two specimens S1 and S2 intersect.

[0121] FIG. 6 is a graph showing the wavelength analysis results of the naturally occurring tannic acid used in Examples, the synthetic tannic acid used in Comparative Example 3, and the RF (dihydric phenol) of Comparative Example 4 according to infrared spectroscopy. In the figure, the graph shown at the top (or left) relates to RF, the graph shown at the bottom (or right) relates to a synthetic tannic acid, and the graph shown in the center relates to a naturally occurring tannic acid. A peak observed in the vicinity of a commonly identified wavenumber of about 1600 to 1620 cm.sup.−1 is a peak for an aromatic ring. RF condensate and tannic acid commonly have a benzene ring, but RF is known as a hazardous substance. On the other hand, tannic acid is a non-hazardous substance except for direct inhalation of dust. On the other hand, in the case of a naturally occurring tannic acid and a synthetic tannic acid, it is confirmed that they are distinguished according to the presence or absence of a peak near a wavenumber of about 1700 cm.sup.−1. The peak near the wavenumber of 1700 cm.sup.−1 is a peak appearing in the C═O bond. This peak is considered to be due to the C═O bond generated in the process of artificially synthesizing tannic acid. That is, it can be seen that synthetic tannic acid and naturally occurring tannic acid are distinguished from each other in that the C═O-containing unit is smaller in naturally occurring tannic acid.

DESCRIPTION OF SYMBOLS

[0122] 10: raw cord [0123] 11: primarily twisted yarn [0124] 12: primarily twisted yarn [0125] 20: coating layer [0126] 21: first coating layer [0127] 21′: first coating liquid [0128] 22: second coating layer [0129] 22′: second coating liquid [0130] 30: tire cord [0131] 100: first winder [0132] 200: first coating tank [0133] 300: first drying device [0134] 400: second coating tank [0135] 500: second drying device [0136] 600: second winder [0137] 1000: tread [0138] 2000: shoulder [0139] 3000: sidewall [0140] 4000: cap ply [0141] 5000: belt [0142] 6000: body fly or carcass [0143] 7000: inner liner [0144] 8000: apex [0145] 9000: bead

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0146] 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 thereby in any way.

Preparation of Compositions of Examples and Comparative Examples

[0147] The compositions of Examples and Comparative Examples were prepared by performing the mixing and stirring under the same conditions except that that the content (wt. %) ratio was the same as in Table 1 below. Specifically, each component was mixed and stirred at about 20° C. for 24 hours.

TABLE-US-00001 TABLE 1 Nitrogen Acid Sum of Solid Sol- compound com- component content vent.sup.1) (NH.sub.3) ponent.sup.2) Latex.sup.3) content (TSC) Example 1  76.30 0.80 3.40 19.50 100 23.70 Example 2  80.00 0.70 2.90 16.40 100 20.00 Example 3  77.50 0.80 3.20 18.50 100 22.50 Example 4  75.00 0.90 3.60 20.50 100 25.00 Example 5  76.30 1.00 3.40 19.30 100 23.70 Example 6  76.30 1.20 3.40 19.10 100 23.70 Example 7  76.30 1.00 4.20 18.50 100 23.70 Example 8  76.30 1.10 4.60 18.00 100 23.70 Example 9  76.30 1.20 5.00 17.50 100 23.70 Example 10 76.30 1.30 5.40 17.00 100 23.70 Comparative 77.04 0.06 3.40 19.50 100 22.96 Example 1 Comparative 78.90 0.80 0.80 19.50 100 21.10 Example 2 Comparative 78.30 0.80 3.40.sup.4) 17.50 100 21.70 Example 3 Reference 76.30 1.30 5.40.sup.5) 17.00 100 23.70 Example 1 Unit: wt. % .sup.1)Solvent (non-solid component): The amount of water (pure water) charged in Examples and Comparative Examples was about 40 to 50 wt. %, and the other solvents were solvents used to disperse acids, nitrogen compounds, and latex. .sup.2)Acid component: Naturally occurring tannic acid was used unless otherwise specified. .sup.3)Latex: VP latex was used. .sup.4)In Comparative Example 3, synthetic tannic acid manufactured by Sigma-Aldrich was used. .sup.5)In Reference Example 1, HiRENOL KOSABOND-R50 produced by Colon Industries was used as RF (dihydric phenol) which is an acid component.

Experiment 1: Measurement of Relative Viscosity of Compositions of Examples and Comparative Examples

[0148] The viscosity of the adhesive composition having the components shown in Table 1 was measured after being left for 30 minutes in a constant temperature water bath (about 25° C.) using an Ubbelohde viscometer. Specifically, a certain amount of demineralized water was put into the Ubbelohde viscometer through the following process, the viscosity characteristics of demineralized water were measured. After measuring the viscosity characteristics of the composition in the same way, the relative viscosity was calculated based on the previously measured viscosity characteristics of demineralized water. The results are shown in Table 2.

[0149] The viscosity measurement process will be described below with reference to FIG. 1. [0150] (1) The sample (composition or demineralized water) was injected into tube A of the Ubbelohde viscometer. [0151] (2) The constant temperature water bath was set to 25° C., then part C was fixed so as to be submerged in a water bath, and left for 30 minutes. [0152] (3) Using a pipette filler, the sample was set so as to reach the center of part C. [0153] (4) After that, the sample was flown downward, and the time required for the liquid level of the sample to pass through the upper scale of B and pass the lower scale of B was measured. [0154] (5) The measured time was applied to the following relative viscosity calculation formula to obtain the relative viscosity.

[0155] <Relative Viscosity Calculation Formula>

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

[0156] In the above formula, T.sub.1 is the time required for the adhesive composition to pass through the upper scale of B and pass through the lower scale of B, and T.sub.0 is the time required for the demineralized water to pass through the upper scale of B and pass through the lower scale of B.

TABLE-US-00002 TABLE 2 Relative viscosity Example 1 2.51 Example 2 2.46 Example 3 2.55 Example 4 2.58 Example 5 2.54 Example 6 2.59 Example 7 2.62 Example 8 2.68 Example 9 2.75 Example 10 2.79 Comparative Example 1 2.21 Comparative Example 2 2.04 Comparative Example 3 2.13 Reference Example 1 2.36

[0157] From Tables 1 and 2, it is confirmed that the viscosity of the adhesive composition varies depending on the components forming the composition and their contents. The component, content, and viscosity of the adhesive affect color characteristics and adhesive force, as in the experiments described below.

Experiment 2: Measurement of Color Difference of Dipped Cord

[0158] 2 Strands of primarily twisted yarns (Z-direction) having a twist number of 360 TPM using a polyester yarn were prepared, and then the 2 strands of primarily twisted yarns were secondarily twisted (S-direction) together with a twist number of 360 TPM to prepare a plied twisted yarn (1650 dtex/2 ply). The plied twisted yarn thus prepared was used as a raw cord 10.

[0159] The polyester raw cord was dipped in the first coating liquid, and then treated for about 1 minute at a drying temperature of 150° C. and a curing temperature of 240° C., respectively, to form a first coating layer 21 and thereby, a reactive active group was imparted to the cord. At this time, the first coating liquid was prepared by mixing an epoxy compound and an isocyanate compound, which are some of the components used in Preparation Example 2, in a weight ratio of about 1:2, together with 97% by weight of demineralized water.

[0160] Then, the raw cord on which the first coating layer was formed was dipped in the second coating liquid (adhesive compositions prepared in Examples and Comparative Examples), dried and cured to form the second coating layer 22. At this time, drying and curing were performed for about 1 minute at a drying temperature of 150° C. and a curing temperature of 235° C., respectively. The dipping step of the first coating liquid and the dipping step of the second coating liquid were performed continuously, and the tension condition at this time was 0.5 g/d. A tire cord 30 was manufactured in the form of a dipped cord through the above process.

[0161] The manufactured tire cord was cut to prepare two square specimens (S1, S2) having a size of 5 cm×5 cm. Specifically, two specimens (S1, S2) in which a plurality of cord strands were closely arranged in one direction were prepared so that 15 to 16 strands per 1 cm were present, and then these specimens were stacked up so that the direction in which the cords of the specimen S1 were arranged and the direction in which the cords of the specimen S2 were arranged were 90°, which were used as the samples for measuring the color difference (see FIGS. 5a and 5b).

[0162] The color difference (L, a, b) of each sample was measured 10 times using a spectrophotometer (CCM, X-rite color-eye 7000A), and the arithmetic mean value was obtained. The results are shown in Table 3 below.

TABLE-US-00003 TABLE 3 L a b Example 1 54.96 5.04 17.59 Example 2 53.19 4.99 17.53 Example 3 54.01 7.20 21.41 Example 4 55.78 7.19 21.33 Example 5 54.61 6.97 21.20 Example 6 54.72 7.00 21.00 Example 7 55.67 7.04 21.00 Example 8 55.34 6.91 22.55 Example 9 56.39 7.21 22.75 Example 10 57.34 7.44 23.04 Comparative 44.17 5.64 12.65 Example 1 Comparative 40.23 5.92 11.52 Example 2 Comparative 46.52 5.66 9.71 Example 3 Reference 52.63 12.56 15.38 Example 1

[0163] It is confirmed that Examples containing an appropriate amount of naturally occurring tannic acid along with other components show the above-mentioned L*, a*, and b* values. That is, the tire cord according to Examples had a dark auburn color. On the other hand, it is confirmed that Comparative Examples 1 to 3 do not generally satisfy the L* value among the color difference values.

[0164] Specifically, when confirmed with the naked eye, Reference Example 1 showed a light auburn color, and Examples showed a darker auburn-based color. This is judged to be because the L* value and the a* value of Reference Example 1 are generally low, and the a* value is generally high, as compared with Examples.

[0165] In addition, in the case of Comparative Examples in which the L and b values were generally lower than in Examples, it showed generally purple.

Experiment 3: Evaluation of Adhesive Force

[0166] The adhesive force per unit area to the tire cords manufactured in Experiment 2 was evaluated. The adhesive force evaluation was performed by measuring the adhesive peel strength of the tire cord using the method of ASTM D4393.

[0167] Specifically, 0.6 mm thick rubber sheet, cord sheet (corresponding to S.sub.1, which is one of the specimens manufactured in Experiment 2), 0.6 mm thick rubber sheet, and cord sheet (corresponding to S1, which is one of the specimens manufactured in Experiment 2), 0.6 mm thick rubber sheet were sequentially laminated, and vulcanized at 170° C. under a pressure of 60 kg/cm.sup.−1 for 15 minutes to prepare a sample. Then, the sample was cut to prepare a specimen having a width of 1 inch. For reference, the rubber sheet has the composition shown in Table 4 below, and is a sheet used for carcass constituting the tire. By using a laminate utilizing such a rubber sheet, the adhesive force of the tire cord to the carcass layer can be confirmed.

[0168] For the prepared specimen, a peeling test was performed at 25° C. at a speed of 125 mm/min using a universal material tester (Instron) to measure the adhesive force of the tire cord to the carcass layer, and the relative magnitudes of the measured adhesive forces are shown in Table 5 below. At this time, the average value of three times the load generated during peeling was calculated as the adhesive force.

TABLE-US-00004 TABLE 4 Content (weight ratio based on 100 parts Rubber sheet component by weight 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 Phenylbetataphthalamine 1.0

TABLE-US-00005 TABLE 5 Adhesive composition used in Adhesive the manufacture of cords force (kgf) Example 11 Example 1 17.4 Example 12 Example 2 15.6 Example 13 Example 3 16.4 Example 14 Example 4 16.3 Example 15 Example 5 16.7 Example 16 Example 6 16.7 Example 17 Example 7 17.1 Example 18 Example 8 17.8 Example 19 Example 9 17.7 Example 20 Example 10 17.8 Comparative Comparative Example 1 8.1 Example 4 Comparative Comparative Example 2 6.9 Example 5 Comparative Comparative Example 3 11.5 Example 6 Reference Reference Example 1 15.6 Example 2

[0169] From Table 5, it is confirmed that Examples provide stronger adhesive force than that of Comparative Examples.

[0170] In addition, comparing Reference Example 2 with Examples, it can be seen that the present invention not only provides an adhesive force equal to or higher than that of the prior art, but also has less harmful to the human body and is eco-friendly.