JP2001192465A - Rubber product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rubber product which has characteristics close to the elastic characteristics of human skins and is suitable for uses directly brought into contact with the skins. SOLUTION: This rubber product characterized in that 200% modulus M200 is <=15 kgf/cm2 (14.7×105 Pa) and in that the ratio M200/M100 of 200% modulus M200 to 100% modulus M100, the ratio M300/M200 of 300% modulus M300 to 200% modulus M200, and the ratio M400/M300 of 400% modulus M400 to 300% modulus M300 are each <=2.0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber product having characteristics close to the elastic characteristics of human skin and suitable for use in direct contact with the skin.

[0002]

2. Description of the Related Art Conventionally, natural rubber is generally used for rubbers used for direct contact with the skin, such as diapers, napkins, gloves, masks, clothes (socks, underwear, etc.). Such rubber products are required to have the following characteristics.

[1] The elasticity of the skin of the human body is adjusted so that it can sufficiently follow the expansion and contraction of the skin, and exhibit the desired adhesion and sealing properties without causing poor blood circulation due to excessive tightening. Have similar elastic properties. In other words, it shows good rubber properties, which are deformed with a small force in accordance with the expansion and contraction of the skin to develop an appropriate tightening force, and return to the original state immediately after removing the force.

[2] It does not contain allergic components and does not cause problems such as inflammation even when directly touching the skin.

[3] It is excellent in stretchability and workability, has no temperature dependency, and can maintain its properties for a long time without being affected by the use environment.

[0006]

However, a rubber product close to the elastic characteristics of human skin has not been developed, and the conventional rubber product has a relatively high elastic stress. Unable to follow skin expansion and contraction enough,
Depending on the product design, it may not be possible to express sufficient adhesiveness or sealability, or conversely, if tightening is too strong, it may cause discomfort or discomfort. there were.

Conventionally, as a product standard, JIS K
637, the tensile strength of the rubber thread is 150 kgf / cm.
² (1.47 × 10 ⁷ Pa) or more, elongation of 60% or more, permanent elongation of 13% or less (supplementary 300% modulus 2
Although there is a standard of 5 kgf / cm ² (2.45 × 10 ⁶ Pa) or less), such a standard does not make it possible to obtain good rubber properties that sufficiently follow the expansion and contraction of human skin.

Further, conventional rubber products are mainly made of natural rubber containing allergic components (proteins), so that there is a risk of inflammation when directly touching the skin. For this reason, it may be used by covering it with non-woven fabric, etc.
In this case, there are drawbacks that the processing cost rises due to the cover material and that the inherent performance of the rubber is impaired.

[0009] Elastic bodies such as TPE (thermoplastic elastomer) have also been provided for use in direct contact with the skin, but these are inferior in workability and settability, and have a large temperature dependency. There is a drawback that the stability of the stretching characteristics is poor.

An object of the present invention is to solve the above-mentioned conventional problems and to provide a rubber product having characteristics close to the elastic characteristics of human skin and suitable for use in direct contact with the skin.

[0011]

According to the present invention, there is provided a rubber product comprising:
00% modulus M₂₀₀Is 15kgf / cm²(1
4.7 × 10⁵Pa) or less, preferably 10 kgf / c
m²(9.8 × 10⁵Pa) or less and 200%
Duras M₂₀₀And 100% modulus M₁₀₀Ratio M with
₂₀₀/ M₁₀₀, 300% modulus M₃₀₀And 20
0% modulus M ₂₀₀Ratio M with₃₀₀/ M₂₀₀as well as
400% modulus M₄₀₀And 300% modulus M
₃₀₀Ratio M with₄₀₀/ M₃₀₀Is 2.0 or less
Lower, preferably 1.5 or less.

M₂₀₀≤15kgf / cm²(14.7
× 10⁵Pa), the modulus ratio M ₂₀₀/ M₁₀₀≤
3.0, M₃₀₀/ M₂₀₀≦ 3.0, M₄₀₀/ M
₃₀₀Low modulus and low modulus ratio of ≦ 2.0
For rubber products, the elastic properties of human skin shown in Fig. 2
Is exhibited.

That is, a material having such a modulus has a tensile characteristic as shown by a solid line in FIG. 1, and a material having such a tensile characteristic has a stretching characteristic very similar to that of a human skin. Is shown. On the other hand, what is indicated by a broken line in FIG. 1 is the tensile properties of thread rubber used in a conventional general paper diaper and the like, but is significantly different from the elastic properties of the human body (the conventional products are: In general, the 200% modulus M ₂₀₀ is larger than 15 kgf / cm ² , and the modulus ratio exceeds 2.0.), Sufficient adhesion without causing poor blood circulation due to excessive tightening,
It is difficult to obtain a sealing property.

Further, since the rubber product of the present invention is easily deformed by a small force, the elongation at break is 600% or more, particularly 800%.
% Or more are required for handling the product. Further, in order to maintain the sealing performance and the like for a long period of time, the permanent elongation is 1
It is preferably at most 2%.

Further, it does not contain allergic components, that is, a synthetic rubber other than natural rubber, particularly a synthetic isoprene rubber (IR), especially, a cis 1,4 conjugate content of 90%
It is preferable that the above IR be a rubber component.

Further, in order to obtain a low modulus, a low modulus ratio and a low permanent elongation, the specific gravity is 1.06 or less, especially 1.
It is preferably 0 or less.

Further, from the viewpoint of ensuring durability, the elongation rate is 20%.
%, It is desirable that no cracks occur for one month or more.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the rubber product of the present invention will be described below in detail.

The rubber product of the present invention has an M ₂₀₀ ≦ 15 kg.
It has tensile properties of f / cm ² (14.7 × 10 ⁵ Pa) and a modulus ratio of M ₂₀₀ / M ₁₀₀ ≦ 2.0 M ₃₀₀ / M ₂₀₀ ≦ 2.0 M ₄₀₀ / M ₃₀₀ ≦ 2.0. Preferably, the elongation at break is 600% or more and the permanent elongation is 12% or less.

With such a 200% modulus, modulus ratio and elongation, the elasticity of the skin of the human body is very similar.

[0021] From the viewpoint of more responsiveness to the human skin
Is 200% modulus M₂₀₀Is 10kgf / cm²
(9.8 × 10⁵Pa) or less, especially 5 to 10 kgf / c
m²(4.9-9.8 × 10⁵Pa) and modular
Ratio M₂₀₀/ M₁₀₀, M ₃₀₀/ M₂₀₀, M
₄₀₀/ M₃₀₀Is preferably 1.5 or less.
The breaking elongation is 800% or more, and the permanent elongation is 10% or less.
Is particularly preferred.

Further, in order to solve the problem of inflammation due to allergy, the rubber product of the present invention uses 100% synthetic rubber, especially 100% IR, without using any NR containing protein as an allergic component as a rubber component. Is preferred. By not using NR in this way, it can be used without any problem even when it is in direct contact with the skin, eliminating the need for a cover material and exhibiting good rubber properties with excellent skin-tracking properties inherent to the rubber product of the present invention. Will be able to

In the present invention, the IR is preferably one having a cis-1,4 bond content of 90% or more, particularly preferably 96% or more. And good rubber properties can be obtained.

The above-mentioned low modulus, low modulus ratio, and low permanent elongation properties of the rubber product of the present invention can be exhibited by setting the specific gravity to 1.06 or less, particularly 1.0 or less. It becomes possible.

The rubber product of the present invention is particularly suitable for applications in which it comes into direct contact with the skin, such as clothing, and does not require high weather resistance as rubber products used in outdoor environments. In the case where it is kept indoors at 20%,
It is preferable that a good state can be maintained without cracks for one month or more.

Without using NR, preferably using IR, particularly preferably high cis 1,4 bond IR, low modulus, low modulus ratio, high elongation at break, low permanent elongation, low specific gravity, In order to realize weatherable rubber products,
For example, the following components are preferably used.

Antioxidants include phenolic, polyphenolic, polyphenolic / benzimidazole, polyphenolic / wax, polyphenolic /
It is preferable to use a benzimidazole type / wax, and it is particularly preferable to use a polyphenol type / wax or a polyphenol type / benzimidazole type / wax. Here, as the polyphenol, 2,2′-
Methylenebis (4-ethyl-6-tert-butylphenol), 2,2′-methylenebis (4-methyl-6-
tert-butylphenol), 4,4′-butylidenebis (3-methyl-6-tert-butylphenol), 4,4′-thiobis (3-methyl-6-tert)
-Butylphenol), butylated reaction product of p-cresol and dicyclopentadiene, 2,5-di-tert
-Butylhydroquinone and 2,5-di-tert-amylhydroquinone, and in particular, butylated reaction products of 2,2'-methylenebis (4-ethyl-6-tert-butylphenol) or p-cresol with dicyclopentadiene And most preferably, 2-mercaptobenzimidazole or 2-mercaptomethyl. It is preferable to use benzimidazole in combination. Further, it is preferable to use a hindered amine-based antioxidant and an ultraviolet absorber together with such an antioxidant.

That is, if a large amount of a filler containing natural rubber is used, it is easy to obtain relatively high weather resistance. However, if natural rubber is not used, a small amount of filler is used and carbon black is not used. It is difficult to obtain sufficient weather resistance by blending,
The incorporation of the above-mentioned anti-aging agent is an important condition for improving weather resistance.

The amount of the antioxidant used is limited by scorch and cost, and the total amount (including the ultraviolet absorber when using an ultraviolet absorber) is 0.1 to 100 parts by weight of the rubber component. It is preferably 3.0 parts by weight.

In the case of white rubber, it is preferable to mix rutile-type titanium oxide and aluminum-treated rutile-type titanium oxide as white pigments. In this case, the compounding amount is 5 parts by weight with respect to 100 parts by weight of rubber. Above, especially 5-10
It is preferred to use parts by weight.

In order to realize a low modulus and a low modulus ratio, it is better not to add a filler. However, as a reinforcing filler, silica, magnesium carbonate, activated calcium carbonate and the like can be mentioned. Is not more than 30 parts by weight, especially 0 to 20 parts by weight, based on 100 parts by weight of the rubber component.
It is preferred to use parts by weight.

In particular, in order to reduce the permanent elongation of a rubber product, silica having a bulk specific gravity of 90 to 130 g / L is preferable.
g / L).

It is preferable to use sulfur as a vulcanizing agent, and as a vulcanization accelerator, M (2-mercaptobenzothiazole), DM (dibenzothiazyl disulfide), CZ (N-cyclohexyl-2-benzo). Thiazole sulfenamide), NS (Nt-butyl-2-benzothiazolylsulfenamide) and the like can be used. From the viewpoint of permanent elongation and weather resistance, sulfur is added to 100 parts by weight of the rubber component. 0 parts by weight or more, especially 1.0 to 2.0
Parts by weight, 0.4 parts by weight or more of the accelerator CZ, 0.4 to 0.1 parts by weight.
Preferably it is 8 parts by weight.

In the present invention, it is preferable that other plasticizers and the like are not blended.

The rubber product of the present invention is prepared by subjecting a rubber composition having such a compounded component to a temperature of 120 to 160 ° C. and a temperature of 30 to 160 ° C. in a conventional manner.
It can be manufactured by vulcanizing for about 90 minutes.
In particular, vulcanization can vulcanization is usually employed to obtain a long product.

In order to effectively exhibit the skin following property, the gauge of the rubber product of the present invention is preferably 1.0 mm or less, particularly preferably 0.5 mm or less.

[0037]

The present invention will be described more specifically below with reference to examples and comparative examples.

Examples 1 to 6, Comparative Examples 1 to 9 Rubber compositions having the compositions shown in Tables 1 and 2 (however, in addition to the ingredients shown in Tables 1 and 2, 0.5 to 2.0 parts by weight of stearic acid) , 1.0 to 3.0 parts by weight of a zinc compound and the like, and the usual amount of a compounding agent is included in the rubber composition) at 130 ° C. for 40 minutes to form a rubber sample. The physical properties and characteristics were examined by using Table 1, and the results are shown in Tables 1 and 2.

[Modulus, strength, breaking elongation] 0.5 m
For a sample of m (thickness) × 1.0 mm (width) × 100 mm (length), the distance between the marked lines = 10 mm and the tensile speed = 10
By conducting a tensile test at 0 mm / min and a chuck-to-chuck = 30 mm, M ₁₀₀ , M ₂₀₀ , M ₃₀₀ , M
₄₀₀ , strength and elongation at break were measured.

[Permanent elongation] 0.5 mm (thickness) × 1.0
Three samples of mm (width) x 100 mm (length) were examined for permanent elongation when held at 50 ° C for 24 hours at a marked line of 40 mm and an elongation of 100%.

[Allergic] Natural rubber (protein)
It was evaluated based on whether or not it was used.

[Workability] Calender workability (existence of pinholes, sheet skin, roll adhesiveness) was examined by visual observation and evaluated as excellent (優), acceptable (△), and unacceptable (×).

[Weather Resistance] When the film was kept at an elongation of 20% in a room, no cracks were generated for one month or more.

In Tables 1 and 2, * 1 to * 8 indicate the following.

* 1 IR ₂₀₀₀ : IR cis 1,4-conjugate content 98% * 2 Carifrex: IR cis 1,4-conjugate content 91% * 3 Nip seal VN ₃ : Bulk specific gravity 145 g / L * 4 Nip seal ER: Bulk specific gravity 103 g / L * 5 Nocrack SP: Methylbenzylphenol * 6 Nocrack NS-5: 2,2'-methylenebis (4-ethyl-6-tert-butylphenol) * 7 Nocrack NS-30: 4,4 '-Butylidenebis (3-methyl-6-tert-butylphenol) * 8 Nocrack PBK: Butylated reaction product of p-cresol and dicyclopentadiene From Table 1, the rubber product of the present invention has excellent skin-following properties, processability, It shows good settability, weather resistance, etc. and is extremely effective for applications that directly touch the human skin. .

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

As described above in detail, according to the present invention, there is provided a rubber product having characteristics close to the elastic characteristics of human skin and suitable for use in direct contact with the skin.

Since the rubber product of the present invention can sufficiently follow the expansion and contraction of the skin, it is deformed with a small force in accordance with the expansion and contraction of the skin to express an appropriate tightening force. Good rubber properties returning to the state can be maintained for a long time. Therefore, desired adhesion and sealing characteristics can be effectively exhibited without causing a problem such as poor blood circulation due to excessive tightening.

According to the second to sixth rubber products, a rubber product having more excellent rubber properties is provided.

According to the rubber products of the seventh to ninth aspects, there are provided rubber products which do not contain allergic components and do not cause problems such as inflammation even when they are directly touched with the skin.

According to the rubber product of the tenth aspect, rubber having a low modulus, a low modulus ratio and a low permanent elongation can be easily realized.

According to the rubber products of claims 12 to 14, a rubber product having excellent weather resistance and durability is provided.

[Brief description of the drawings]

FIG. 1 is a graph showing tensile properties of a rubber product of the present invention and a conventional product (thread rubber for paper diapers).

FIG. 2 Skin elasticity characteristics (stress-strain curves) at various parts of the human body
FIG.

Claims (14)

[Claims] 1. 200% modulus M₂₀₀Is 15kg
f / cm²(14.7 × 10⁵Pa) or less, 200% modulus M₂₀₀And 100% modulus M
₁₀₀Ratio M with₂₀₀/ M₁₀₀, 300% modulus
M₃₀₀And 200% modulus M₂₀₀Ratio M with ₃₀₀
/ M₂₀₀And 400% modulus M₄₀₀And 300%
Modulus M_{30 0}Ratio M with₄₀₀/ M₃₀₀Is any
Is also 2.0 or less. 2. The method according to claim 1, wherein the 200% modulus M ₂₀₀ is 10 kgf / cm ² (9.8 × 10 ⁵ Pa).
A rubber product characterized by the following. 3. The ratio M of 200% modulus M ₂₀₀ to 100% modulus M _{100 according} to claim 1 or 2.
₂₀₀ / _M 100, 300% modulus _{M 3 00} 20
0% The ratio _M 300 _{/ M 200} and 400% modulus _{M 400} of the modulus _{M 200} and 300% modulus M
Rubber _{products 300} the ratio of the _M 400 _{/ M 300} is equal to or either 1.5 or less. 4. The rubber product according to claim 1, wherein a breaking elongation is 600% or more. 5. The method according to claim 4, wherein the elongation at break is 800%.
A rubber product characterized by the above. 6. The rubber product according to claim 1, wherein a permanent elongation is 12% or less. 7. A rubber product according to claim 1, wherein the rubber component is a synthetic rubber other than natural rubber. 8. The rubber product according to claim 7, wherein the synthetic rubber is a synthetic isoprene rubber. 9. The rubber product according to claim 8, wherein the content of the cis 1,4 conjugate in the synthetic isoprene rubber is 90% or more. 10. The rubber product according to claim 1, having a specific gravity of 1.06 or less. 11. The rubber product according to claim 10, wherein the specific gravity is 1.0 or less. 12. The rubber product according to claim 1, wherein no cracks are generated for one month or more when held at an elongation of 20%. 13. The rubber product according to claim 1, further comprising a polyphenol or a polyphenol / wax-based antioxidant as the antioxidant. 14. The method according to claim 13, wherein the polyphenol is 2,2′-methylenebis (4-ethyl-6-tert.
-Butylphenol), or a butylation reaction product of p-cresol and dicyclopentadiene.