JP2012182999A - Rubber composition for teat cup liner and teat cup liner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber composition for a teat cup liner that improves bending fatigue durability and the teat cup liner using the rubber composition.SOLUTION: The teat cup liner 2 is formed as a cylindrical shape by using the rubber composition. The teat cup liner 2 includes: a first opening 3 into which a teat T is inserted; a second opening 4 opposing to the first opening 3; a body 22 formed at the side of the first opening 3; a short milk tube 23 thicker than the body 22 formed at the side of the second opening 4. The rubber composition for the teat cup liner includes nitrile rubber and carbon black.

Description

  The present invention relates to a rubber composition for a teat cup liner used in a milking apparatus and a teat cup liner using the rubber composition.

  Conventionally, a teat cup is attached to a teat when milking a mammal such as a cow using a milking device. For example, a plurality of teat cups are provided in one milking apparatus, and include a teat cup liner that receives a teat and a cylindrical teat cup shell that is mounted around the teat cup liner. The teat cup shell is made of, for example, a metal such as stainless steel, and the inside of the teat cup shell and the pneumatic pulsator are connected by a tube. The teat cup liner is a substantially cylindrical member integrally formed of a rubber composition, and has a body portion that pulsates within the teat cup shell, and a short milk tube that extends outside the teat cup shell. (For example, see Patent Document 1).

  However, especially the short milk tube in the teat cup liner has been cracked or cracked due to bending fatigue due to repeated bending deformation during milking work or storage. For this reason, teat cup liners are generally replaced, for example, in about 6 months before milking failure due to cracks occurs.

JP 2008-92987 A

  An object of the present invention is to provide a rubber composition for a teat cup liner having improved bending fatigue durability and a teat cup liner using the rubber composition.

The rubber composition for teat cup liners according to the present invention is:
Including nitrile rubber and carbon black,
The carbon black has an average particle diameter of at 80nm inclusive 18 nm, there is the DBP absorption below 90cm ^3/100 g or more 160cm ^3/100 g, with respect to the nitrile rubber 100 parts by weight 40 parts by weight to 55 parts by weight Includes:

  According to the rubber composition for a teat cup liner according to the present invention, a teat cup liner having improved bending fatigue durability can be formed.

In the rubber composition for teat cup liners according to the present invention,
Hardness (JIS-A) can be 50 degrees or more and 56 degrees or less.

The teat cup liner according to the present invention is formed into a cylindrical shape using the rubber composition for a teat cup liner,
A first opening into which the nipple is inserted; a second opening facing the first opening; a body formed on the first opening side; and the second opening side A short milk tube that is thicker than the body formed in the body.

  According to the teat cup liner according to the present invention, the bending fatigue durability of the short milk tube can be improved.

It is a longitudinal cross-sectional view of a teat cup liner and is a figure which shows the state of a suction period. It is a longitudinal cross-sectional view of a teat cup liner, and is a figure which shows the state of a rest period. It is a side view which shows the state at the time of storage of a teat cup. It is a side view which shows the bending test apparatus of a teat cup liner. It is a side view which shows operation | movement of the bending test apparatus of a teat cup liner.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

The rubber composition for a teatcup liner according to an embodiment of the present invention includes nitrile rubber and carbon black, and the carbon black has an average particle size of 18 nm to 80 nm and a DBP absorption of 90 cm ³ / It is 100g or more and 160cm < ³ > / 100g or less, Comprising: 40 mass parts or more and 55 mass parts or less are included with respect to 100 mass parts of said nitrile rubber.

  A teatcup liner according to an embodiment of the present invention is formed into a tubular shape using the rubber composition for a teatcup liner, and includes a first opening into which a teat is inserted, and the first opening. It has the 2nd opening part which opposes, the trunk | drum formed in this 1st opening part side, and the short milk tube thicker than this trunk | drum formed in this 2nd opening part side.

FIG. 1 is a longitudinal sectional view of a teat cup liner 2 according to the present embodiment, and shows a state in a suction period. FIG. 2 is a vertical cross-sectional view of the teat cup liner 2 according to the present embodiment, and shows a state in a rest period.
The teat cup 10 is a milking device that is mounted on a teat T such as a cow, and includes a teat cup liner 2 that receives the teat T and a cylindrical teat cup shell 1 that is mounted around the teat cup liner 2. ing.

  The teat cup shell 1 has a cylindrical shape made of metal, for example, stainless steel, and a vacuum chamber 24 is formed between the teat cup shell 1 and the teat cup liner 2 inserted therein. The vacuum chamber 24 is connected to a pulsator (not shown) via a tubular connection part 13 protruding from the side surface of the teat cup shell 1 and a tube (not shown) connected to the connection part 13. The pulsator can change the atmospheric pressure in the vacuum chamber 24 by alternately switching between the vacuum pressure and the atmospheric pressure at a preset predetermined period, for example, about 1 second.

  The teat cup liner 2 is integrally formed of a flexible rubber composition. The teat cup liner 2 is formed, for example, in a cylindrical shape having ducts 26A and 26B having a circular cross section inside, and a first opening 3 into which the teat T is inserted and a first opening 3 are formed. The head 21, the second opening 4 facing the first opening 3, the body 22 formed on the first opening 3 side, and the second opening 4 side. A short milk tube 23 that is thicker than the body 22. The head portion 21 has a lip portion 25 that is formed to expand outward from the body portion 22 and projects inwardly at the tip thereof, and a skirt portion 27 that extends in a substantially cylindrical shape toward the body portion 22 side. The first opening 3 is formed at the inner peripheral edge of the lip portion 25. The trunk portion 22 is pulsated by the pulsator, so that the trunk portion 22 is formed to be relatively thin, and a conduit 26A through which the milk M from the teat T flows is formed inside. At the lower end of the body portion 22, a diameter-enlarged portion 29 that is expanded outward from the body portion 22 is formed. In the teat cup shell 1, one opening portion 11 is disposed between the skirt portion 27 and the body portion 22, and the other opening portion 12 is fitted in the fitting groove 28, and is integrated with the teat cup liner 2. The short milk tube 23 is formed in a substantially cylindrical shape extending from the enlarged diameter portion 29 of the trunk portion 22, and the second opening 4 is formed at the end thereof.

  The short milk tube 23 is connected so that the second opening 4 is connected to a milking vacuum line of a pulsator (not shown), and the pressure in the pipe line 26B of the short milk tube 23 is constantly adjusted to a negative pressure. As shown in FIG. 1, when the vacuum chamber 24 is in a vacuum pressure state, that is, during the suction period, the central region of the conduit 26A of the trunk portion 22 is open, and the milk M passes through the conduits 26A and 26B. It is sucked into the pulsator. As shown in FIG. 2, in an atmospheric pressure state in which air is introduced into the vacuum chamber 24, that is, in a rest period, the opposing surface of the central region of the pipe line 26A of the trunk portion 22 is in close contact, and the pipe line 26A is closed. The suction of the milk M can be stopped. In the inhalation period and the suction period during the milking operation, the pipe line 26B of the short milk tube 23 is always open, but when the milking operation is not performed, for example, during storage, the short milk tube as shown in FIG. 23 may be bent halfway. When the short milk tube 23 is bent as described above, the pipe line 26B can be closed at the bent portion X. Moreover, the thickness A (refer FIG. 1, 2) of the short milk tube 23 can be 2.5 mm or more and 3.8 mm or less. As shown in FIGS. 1 and 2, the short milk tube 23 can have a uniform thickness except in the vicinity of the tip where the irregularities are formed. Since the wall thickness A of the short milk tube 23 can be made thinner than before, the material cost in the short milk tube 23 can be reduced. In addition, by reducing the thickness A, the operator tends to easily understand that the milk M is moving in the short milk tube 23 during milking.

The rubber composition used for the teat cup liner 2 comprises a nitrile rubber and carbon black, carbon black has an average particle diameter of at 80nm inclusive 18 nm, DBP absorption of 90cm ^3/100 g or more 160cm ^3/100 g or less And it is 40 mass parts or more and 55 mass parts or less with respect to 100 mass parts of nitrile rubber. The average particle size of carbon black is an average value calculated by measuring the diameter of small spherical components constituting the carbon black aggregate with an electron microscope. The average particle size of the carbon black can be further 20 nm or more and 75 nm or less, and particularly 27 nm or more and 72 nm or less. DBP absorption of carbon black can be even not greater than 100 cm ^3/100 g or more 160cm ³ / 100g. DBP absorption is a DBP of the carbon black 100g absorbs (dibutyl phthalate) amount ^(cm 3 / 100g), measured in accordance with JIS K6217-4 (ASTM D 2414). The structure, which is the degree of development of the aggregate in which the carbon black particles are fused, can be indirectly quantified by the DBP absorption amount. The bending fatigue durability of the rubber composition can be improved by using high structure carbon black having a large DBP absorption. Further, the mass part indicates “phr” unless otherwise specified, and “phr” is an abbreviation for “parts per undred of rubber” and represents the percentage of an additive such as an additive to rubber. By blending such carbon black, even if the amount of carbon black is relatively small, it can be moderately reinforced while maintaining the flexibility of nitrile rubber, and the bending fatigue durability of the short milk tube of the teat cup liner Can be improved.

  The hardness (JIS-A) in the rubber composition used for the teat cup liner can be 50 degrees or more and 56 degrees or less, and can be 51 degrees or more and 54 degrees or less. The hardness of the rubber composition used for the teat cup liner is preferably within a predetermined range so as not to give stress to the cow during milking, and is adjusted by the amount of plasticizer and the amount of carbon black. be able to. Specifically, increasing the amount of carbon black increases the hardness, and increasing the plasticizer decreases the hardness. A known plasticizer can be used as the plasticizer.

The nitrile rubber in the rubber composition used for the teat cup liner is a copolymer of acrylonitrile and butadiene, and is flexible in that it does not give excessive stress to the cow during milking, and it is relatively inexpensive and has excellent fatigue durability. Therefore, the nitrile content can be 18% by mass or more and 25% by mass or less, and the Mooney viscosity ML _{1 + 4} (center 100 ° C.) can be 30 or more and 80 or less.

(Examples 1-10, Comparative Examples 1-2)
(1) Preparation of rubber composition samples Examples 1 to 10 and Comparative Examples 1 and 2 were kneaded using a 6-inch open roll with the composition shown in Tables 1 to 3, and the dispensed rubber composition was set in a mold. Then, press crosslinking was performed at 145 ° C. for 20 minutes to obtain a rubber composition sample. The formulations are shown in Tables 1-3. The materials used were as follows.
1. Nitrile rubber (NBR): nitrile content 20 mass%, Mooney viscosity ML _{1 + 4} (central value 100 ° C.) 63.
2. Carbon black: MAF-HS, HAF, HAF-HS, FEF-HS, SRF-HS, FEF, SRF. Each particle diameter (D (nm)) and DBP absorption ^{(DBP (cm 3 / 100g)} ) are shown in Table 4.
3. Plasticizer, sulfur, vulcanization accelerator, zinc white, anti-aging agent, stearic acid.

(2) Measurement of normal physical properties As normal physical properties, hardness at room temperature, 100% and 300% modulus, tensile strength, elongation at break, and compression set were measured for Examples 1 to 10 and Comparative Examples 1 and 2. The measurement results are shown in Tables 1-3.

  Rubber hardness (shown as “Hs (JIS-A)” in Tables 1 to 4) was measured based on JIS K 6253.

  Stress at 100% elongation (shown as “σ100 (MPa)” in Tables 1 to 3), stress at 300% elongation (shown as “σ300 (MPa)” in Tables 1 to 3), tensile strength The length (indicated by “TS (MPa)” in Tables 1 to 3) and the elongation at break (indicated by “EB (%)” in Tables 1 to 3) were cut into a JIS No. 3 dumbbell shape. The test piece was measured by performing a tensile test based on JIS K6251 at 23 ± 2 ° C. and a tensile speed of 500 mm / min using a tensile tester manufactured by Ueshima Seisakusho. “Σ100” and “σ300” may be referred to as “100% modulus (M100)” and “300% modulus (M300)”.

  The compression set rate (shown as “CS (%)” in Tables 1 to 3) was measured based on JIS K 6262. The measurement conditions were 25% compression, 70 ° C., and 22 hours.

(3) Product Evaluation The teat cup liner shown in FIG. 1 was prepared with the formulation of Comparative Examples 1-2 and Examples 1-10, and a bending test was performed. The results are shown in Tables 5-7.
Comparative Examples 1-2 and Examples 1-5 used teat cup liners molded with the same mold. The wall thickness A of the short milk tube was 3.9 mm.
Example 6-10 was a teat cup liner formed using a mold (core) with an expanded inner diameter of a short milk tube, and the wall thickness A of the short milk tube was 3.6 mm.
In addition, as Examples 11 to 14, a teat cup liner formed using a mold in which the thickness A of the short milk tube was changed from 3.0 mm to 3.9 mm using the rubber composition of Example 1. Was used to perform a bending test. The results of Examples 11 to 14 are shown in Table 6.
Further, as Examples 15 to 16, a teatcup liner molded using a mold in which the thickness A of the short milk tube was changed to 2.7 mm and 3.9 mm using the rubber composition of Example 6 Was used to perform a bending test. The results of Examples 15 to 16 are shown in Table 7.

The bending test was performed using a bending test apparatus 30 shown in FIGS. FIG. 4 is a side view showing the bending test apparatus 30 of the teat cup liner 10. FIG. 5 is a side view showing the operation of the bending test apparatus 30 for the teat cup liner 10. The bending test apparatus 30 includes a substrate 33 fixed on the machine base 32 and an air cylinder 34 fixed to the substrate 33. A lift plate 35 connected to the teat cup shell 1 is fixed to the tip of the drive rod 36 of the air cylinder 34 and can be lifted and lowered by the air cylinder 34. The teat cup liner 10 of Examples 1 to 16 is installed in the bending test apparatus 30 as shown in FIG. 4, and the drive rod 36 is driven by the air cylinder 34 to lower the teat cup shell 1 as shown in FIG. The short milk tube 23 was bent and further bent by being raised to the state shown in FIG. The tip of the short milk tube 23 was fixed to the machine base 32 via a connection portion (not shown). As shown in FIG. 5, large deformation portions 230, 231, and 232 were observed during the bending operation of the short milk tube 23, and the number of occurrences of cracks (shown as “bending test (× 10 ⁴ )” in Tables 5 to 7). ) Is shown in Tables 5-7. In Examples 11 and 12, the test was stopped because cracks did not occur even when it was repeatedly bent 1.62 million times.

  According to Tables 5-7, compared with the teatcup liner of Comparative Example 2, the number of times of bending until the cracks occurred in the short milk tube in the teatcup liners of Examples 1 to 16 was more than 80,000 times. . Therefore, the teat cup liners and rubber compositions of Examples 1 to 16 were superior in bending fatigue durability. In addition, the teat cup liners of Examples 6 to 13 and Example 16 were excellent in bending fatigue durability even when the thickness A was made thinner than that of the teat cup liner of Comparative Example 2.

  1 teat cup shell, 2 teat cup liner, 3 first opening, 4 second opening, 10 teat cup, 11 opening, 12 opening, 13 connecting part, 21 head, 22 trunk, 23 short milk tube , 24 Vacuum chamber, 26A pipe line, 26B pipe line, 27 skirt part, 28 fitting part, 29 widened part, T nipple, M milk, A wall thickness of short milk tube, X bent part, 30 flex test apparatus, 32 Machine base, 33 Substrate, 34 Air cylinder, 35 Lift plate, 36 Drive rod, 230 to 232 Large deformation area

Claims (3)

Including nitrile rubber and carbon black,
The carbon black has an average particle diameter of at 80nm inclusive 18 nm, there is the DBP absorption below 90cm ^3/100 g or more 160cm ^3/100 g, with respect to the nitrile rubber 100 parts by weight 40 parts by weight to 55 parts by weight A rubber composition for a teat cup liner, comprising: In claim 1,
A rubber composition for teat cup liners having a hardness (JIS-A) of 50 degrees or more and 56 degrees or less. It is formed into a cylindrical shape using the rubber composition for a teat cup liner according to claim 1 or 2,
A first opening into which the nipple is inserted; a second opening facing the first opening; a body formed on the first opening side; and the second opening side A teat cup liner having a short milk tube thicker than the trunk formed on the body.

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