JPH01252663A - Sulfide rubber composition - Google Patents

Abstract

PURPOSE:To obtain the title composition having a decreased tendency to exude or migrate, improved flexibility and increased suitability as a sealant, by mixing a polysulfide as a base with a specified plasticizer. CONSTITUTION:100 pts.wt. polysulfide such as a liquid polymer of an average MW of 4000-7500, obtained by combining an organic compound having a chlorine atom on each end with an alkali polysulfide and having disulfide bonds in the main chain, a small number of branches and mercapto groups on its ends, is mixed with 10-200 pts.wt. compound of the formula (wherein R is a 5-13C alkyl or a cyclohekyl) as a plasticizer and, optionally, a filler such as TiO2, carbon black, pigment, tackifier, cure accelerator, cure retarder, stabilizer, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to sulfide rubber compositions. More specifically, the present invention relates to a sulfide rubber composition that contains a specific plasticizer, has excellent properties, and is suitable for use as a sealant.

Encapsulants manufactured from polysulfide can be cured at room temperature or by heating using a curing agent, and have excellent gas and vapor barrier properties, oxidation resistance, weather resistance, and ozone resistance, and are suitable for various types of cutting, fuel oil, It becomes a rubber with high resistance to acids and alkalis, and excellent low-temperature properties. Also mortar,
Excellent adhesion to glass and metals such as aluminum. Therefore, the encapsulant made from polysulfide is
Can withstand harsh usage conditions and is widely used in construction, aircraft, ships, automobiles, civil engineering, double glazing, and general industrial applications such as wall joint material for high-rise buildings, window frame joint material, and automobiles. It is used for sealing window frames of airplanes, and for sealing aircraft fuel tanks when they are integrated.

When flexibility is required for this polysulfide encapsulant,
The use of plasticizers is essential. Polychlorinated biphenyl (PC) is a plasticizer for conventional polysulfide for encapsulants.
B) has been used.

Although polychlorinated biphenyls have extremely excellent performance as plasticizers, they remain in the environment for a long time because they are highly toxic to living organisms and do not cause any biodegradation reactions.

Polychlorinated biphenyls that have been taken into the body cannot be excreted and accumulate in the body, and the negative effects they have on living organisms are immeasurable.Therefore, polychlorinated biphenyls cannot be used at present.

It is well known that various phthalate esters, phosphate esters, chlorinated paraffins, and the like have been proposed as plasticizers for the sealing material as substitutes for polychlorinated biphenyls. However, these various plasticizers each have their own drawbacks and do not have satisfactory performance compared to conventional polychlorinated biphenyls.

Conventional phthalate ester plasticizers volatilize during long-term use, resulting in deterioration of the flexibility or low-temperature properties of sulfide rubber compositions, and the so-called thinning phenomenon of sulfide rubber compositions. Become. However, di-2-ethylhexyl phthalate (DOP), which is one of the phthalate ester plasticizers, occupies a major position as a plasticizer for polysulfide.

Phosphate ester plasticizers have poor cold resistance, poor plasticization efficiency, and poor stability against light and heat. Chlorinated paraffins also have poor thermal stability and dehydrochlorinate when heated, corroding the substrate. If the chlorine content is 50 or more, it may cause
Only about 60% of them are used.

Therefore, desirable properties of the plasticizer used in the sulfide rubber composition are as follows. In other words, it has good compatibility with polysulfide.

Good plasticization efficiency, low volatility, low heat loss, no oozing from sulfide rubber after curing,
Examples include low migration properties. Another important property is that it is non-toxic to living organisms.The present invention aims to provide a sulfide rubber composition suitable for a sealing material that satisfies the above performance.

The sulfide rubber composition of the present invention is a composition containing polysulfide as a main component and using a compound represented by general formula (1) as a plasticizer.

(In the formula, R is alkyl having 5 to 13 carbon atoms or cyclohexyl.) Specific examples of the compound represented by the above formula (1) include the following. Pentylbenzyl phthalate, hexylbenzyl phthalate, heptylbenzyl phthalate, octylbenzyl phthalate, 2-ethylhexylbenzyl phthalate, nonylbenzyl phthalate, isononylbenzyl phthalate, decylbenzyl phthalate, isodecylbenzyl phthalate , undecylbenzyl phthalate, isoundecylbenzyl phthalate, dodecylbenzyl phthalate, isododecylbenzyl phthalate, tridecylbenzyl phthalate, and isotridecylbenzyl phthalate. General formula (
The compound represented by I) can be obtained by a numerical production method such as a sodium salt of a phthalic acid monoalkyl ester synthesized from phthalic anhydride and alcohol or alcoholade, and a diesterization reaction of this with benzyl chloride. (Unexamined Japanese Patent Publication No. 63-41557, Special Publication No. 4
7-41892).

The plasticizer of the present invention can also be mixed with a compound of general formula (I). In addition, the present invention can be used in combination with various conventionally known plasticizers, such as other phthalate ester plasticizers, phosphate ester plasticizers, chlorinated paraffin plasticizers, and triaryl dimethane plasticizers. It is also possible to use it in combination with a plasticizer.

The polysulfide used in the present invention is a compound in which an organic compound having chlorine atoms at both ends and an alkali polysulfide are combined, and has a disulfide bond in the main chain represented by the following general formula (II), and has a small amount of The average molecule 1 is about 4000 to 75 and has a branched end with a mercaptan group.
00 liquid polymer can be exemplified.

H3(C21(4-OCH20C21(4-55)nc
2H40cH20c2H4s)l (II) This polysulfide is dichloroethyl formal CλCH
2CH20CH20CH2CH2C and sodium disulfide N
For example, Thiokol LP-2, obtained from copolymerization with a52Na and sold by Toshi Thiokol Co., Ltd.
LP-32, LP-12, LP-55゜LP-31
can be mentioned.

The sulfide rubber composition of the present invention is mainly composed of polysulfide and contains a specific plasticizer, and in addition, fillers such as titanium dioxide, zinc sulfide, silica, calcium carbonate, carbon black, pigments, etc. tackifiers, curing accelerators such as sulfur, amines, inorganic bases, curing retarders such as stearic acid, metal stearates, oleic acid, stabilizers, and thixotropic agents to improve extrudability. etc. can be added.

As the hardening agent for the liquid polymer used in the present invention, metal peroxides such as lead dioxide, manganese dioxide, calcium peroxide, and dumbbell peroxide, or organic peroxides such as cumene hydroperoxide and baraquinone dioxime are used. Ru. Lead dioxide is sometimes mixed as a powder, but usually with a suitable diluent. This diluent is often kneaded into a paste using the same plasticizer used for the polysulfide base material.
When lead dioxide is used as a hardening agent, it is said that the amount used is preferably 7.5 parts by weight per 100 parts by weight of liquid polysulfide.

The sulfide rubber composition of the present invention may contain polysulfide obtained by crosslinking a liquid polymer with a curing agent, and a specific plasticizer, but in most cases, it contains a polysulfide base material obtained by kneading liquid polysulfide with a plasticizer, etc. A hardening agent (including a hardening agent paste) is mixed into the material immediately after use, filled or applied to the sealing area with a knife, spatula, or sealing gun, and cured by heating at room temperature.

The proportion of plasticizer used in the sulfide rubber composition according to the present invention can vary widely depending on the place where the sealing material is used, the purpose of use, the conditions of use, etc., but generally it is based on 100 parts by weight of polysulfide. , 10-2
00 parts by weight of lubricant is often included.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example Manufacture and Test Results of Sulfide Rubber Composition Thiokol LP-32, sold by Toshi Thiokol Co., Ltd. and having an average molecular weight of 4,000 and a crosslinking ratio of 0.5, was used as polysulfide.

-i Specific examples of compounds represented by formula (r) Alcohols include 2-ethylhexanol, isononyl alcohol,
Using 2-ethylhexylbenzyl phthalate, isononylbenzyl phthalate, and decylbenzyl phthalate synthesized from decyl alcohol, and adding the additives shown in Table 1 to form a polysulfide base material, cure with this polysulfide base material. Mix the medicine! After, sulfide rubber composition,
Furthermore, the results of testing various physical properties after curing are shown in Table 1. As a comparative example, an example using di-2-ethylhexyl phthalate, which is a plasticizer commonly used at present, was shown.

The test and evaluation method was based on the following JIS or the following method.

Slump (sagging amount mm JIS ^5758-8
6) Hardness (Hs) (Sulfur link type JIS
A3754 5.2>Standard condition, heating 70℃X
Tensile adhesive strength after 96 hours (glass, JIS A3758-86
) Standard condition, peeling after heating at 80°C x 4 weeks M adhesive strength (glass, JIS A3754-75
＞Standard condition: Weight heating condition at 20°C for 7 days after curing
After curing at 100°C x 7 days, weight transferability) is 80
The appearance after heating at °C for 7 days was evaluated according to the following criteria.

Very good: no oozing at all Good: little oozing Poor: oozing As described above, since the composition according to the present invention uses a specific plasticizer as a plasticizer, it does not suffer from the disadvantages of conventional sulfide rubber compositions. It is characterized by far less oozing and migration from objects.

Because of the low oozing and migration of the plasticizer, the composition according to the present invention was found to be resistant to heat loss, hardness change after being left to heat, and change in tensile adhesive strength after being left to heat, which are accelerated tests for long-term use. It changes little and does not lose its flexibility, so that the composition according to the invention can withstand long-term use.

Furthermore, the composition according to the present invention exhibits less oozing and migration from the sulfide rubber composition, and at the same time has an excellent balance of physical properties, and is equal to or better than conventional sulfide rubber compositions in all physical properties.

Table 1 that's all

Claims (1)

[Claims] A sulfide rubber composition containing polysulfide as a main component and a compound represented by general formula (I) as a plasticizer. ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R is alkyl or cyclohexyl having 5 to 13 carbon atoms.)