GB2028840A

GB2028840A - Concrete joint sealant

Info

Publication number: GB2028840A
Application number: GB7907412A
Authority: GB
Original assignee: SHIOMOTO K
Current assignee: SHIOMOTO K
Priority date: 1978-08-30
Filing date: 1979-03-02
Publication date: 1980-03-12
Also published as: JPS5534220A; JPS5724819B2; GB2028840B

Abstract

The present invention relates to a concrete joint sealant which is composed of a coal tar mainly consisting of a distillate obtained at up to 350 DEG C., vinyl chloride resin, coal pitch and a mixture of dioctyl phthalate and dioctyl adipate, as plasticizers.

Description

SPECIFICATION Concrete joint sealant The present invention relates to a concrete joint sealant of uniform qualityexcelling in stability and resistance to oil.

Joints are provided in concrete pavements of roads, airport runways and parking lots to absorb the expansion or contraction of the concrete due to heat. These joints without joint sealant, will lead to destruction of the pavement, as the result of sand, stones, rainwater or melting snow gettingjnto them. Therefore they are usually sealed with a joint sealant. Conventional joint sealants include pitch type substances like asphalt, rubberized asphalt or natural vulcanized substances of poiysulfide synthetic rubber type in the form of two solutions mixed at ambient temperature. Rubberized asphalt requires a long time for heating and melting and is liable to deteriorate by heating.

Polysulfide synthetic rubber is inferior in thermal stability. Particularly, one of the two-solutions blending type is difficult to compound under variations in atmospheric temperature. Accordingly, it is liable to gelate in long storage, resulting in poor workability and an uneven quality in the work after pouring. Also these sealants are required to be resistant to gasoline or jet fuel leaking from vehicles or aircraft on the roads or airport runways to which these sealants are applied. For this reason, vinyl chloride resin has been added to such sealants. However, sealants containing vinyl chloride resin and coal tar are found inferior in storage stability. To improve the storage stability, U.S. Patent No.

3,549,575 teaches a joint sealant composed of a coal tar, i.e. a distillate at a specific high boiling point, and vinyl chloride resin. This new sealant although improving stability, cannot form a uniformly elastic bond when applied to the joint, because a part of the coal tar remains unsolved in the joint due to poor solubility. Besides, its resistance to gasoline or jet fuel is not satisfactory.

The object of the present invention is to provide a concrete joint sealant with high stability and high resistance to oil.

Another object of the present invention is to provide a concrete joint sealant which represents a homogenous compound of vinyl chloride resin and coal pitch and makes an evenly elastic bond when poured into concrete joints.

Still another object of the present invention is to provide a concrete joint sealant which can be poured by heating to a low temperature, accordingly, suffers little thermal deterioration and can be ,worked simply and efficiently.

According to the present invention there is provided a concrete joint sealant composed of a coal tar mainly consisting of a distillate boiling at up to 3500C; vinyl chloride resin; coal pitch; and a mixture of dioctyl phthalate and dioctyl adipate as plasticizers.

The coal tar to be used in the present invention is one mainly composed of a distillate boiling off at up to 3500C which is said to gelate, when compounded with vinyl chloride resin to produce a joint sealant, and to decrease the stability of the product.

The present invention is based upon the discovery that the thermal stability and oil resistance of a joint sealant can be improved by compounding coal tar and vinyl chloride resin with a mixture of specific plasticizers, i.e., dioctyl phthalate and dioctyl adipate and further adding coal pitch thereto.

The coal tar to be used in the present invention is most desirably composed mainly of having more than 50% by weight distillate boiling off at up to 3500C. If a coal tar mainly composed of a distillate boiling off at over 3500C is used and is compounded with vinyl chloride resin and coal pitch, the coal pitch will remain unsolved in the sealant and yield an unstable, poorly elastic bond when poured into the joint. The coal tar used is desirably 10-40 weight of the total weight of the sealant. If it is used in less than 10 weight %, the anti-ageing property of the vinyl chloride resin and the bondability of the sealant will drop. If it is used in more than 40 weight %, the stability of the sealant will be poor.

The coal pitch to be used in the present invention is desirably one with a melting point of 100--1400C. If its melting point exceeds 1 400 C., non-solubles will develop, yieiding a sealant of uneven quality. If the melting point is lower than 1 000C., the sealant obtained is liable to gelate. The pitch is desirable 5-1 5 weight % of the total weight of the sealant.

The vinyl chloride resin to be used in the present invention may be either a homopolymer or a copolymer.

The copolymer may be formed for example with vinyl acetate or with maleate. This resin is preferably used in the form of a paste resin, in a desirable amount of 2-25 weight % of the total weight of the sealant. If the amount used is too much, the viscosity of the sealant will increase, and if it is too little, the sealant will lack elasticity.

As the plasticizer, dioctyl phthaiate and dioctyl and adipate must be combined. If other plasticizers are entployed or the plasticizers are employed singly, a joint sealant with the high stability of the present invention will not be obtained.

The mixture ratio of dioctyl phthalate (DOP) to dioctyl adipate (DOA) can be varied over a wide range. However, the mixture ratio of DOP to DOA is preferably within the range of 19:1 to 4:1 so that a well-balanced sealant is obtained which gives good sol-stability of DOA and good oil resistance. This plasticizer mixture is desirably used in the quantity of 2040 weight of the total weight of the sealant so as to retain adequate softness of the sealant and prevent the sealant from becoming too hard at low temperatures.

The joint sealant according to the present invention desirably has added to it a conventional stabilizer, for instance, dibasic lead phosphite in order to improve the ageing resistance of the vinyl chloride resin.

For the purpose of viscosity adjustment and volume extension of the sealant, a filler such as calcium carbonate, talc, clay, etc., also may be added to the sealant.

The joint sealant according to the present invention can be prepared by blending the abovementioned components, preferably, at 5--300C. for 60-90 min, in an agitator equipped with a cooler.

Before applying to the concrete joint, the sealant is heated to 120-1 600 C. to make flowing into the joint easy. After the sealant is poured it is cooled to the ambient temperature, during which time it solidifies to yield a viscoelastic rubber-like mass, which adhere to the joint concrete.

The present invention will now be described in more detail in the following Example.

EXAMPLE Fifteen parts by weight of coal tar containing 40-65 weight % of a distiilate boiling at up to 3500 C., 10 parts by weight of coal pitch with a softening point of 105-1 08 C. (measured by ball and ring test), 25 parts by weight of dioctyl phthalate and 5 parts by weight of dioctyl adipate were evenly blended in an agitator and then 10 part by weight of vinyl chloride resin were added under agitation.

The speed of the agitator was so controlled that the mass was held to less than 350C. After uniformly dispersing the vinyl chloride resin, 0.5 parts by weight of dibasic lead phosphite and 35 parts by weight of calcium carbonate were added and agitated until they were uniformly dispersed. Thereafter the agitation was stopped and the mass defoamed. The sealant thus yielded was then bottled.

STABILITY TEST Stability was compared between a sealant prepared according to the present invention, a sealant prepared in the same way except that dioctyl phthalate and dioctyl adipate were omitted, and a sealant prepared in the same way except that dioctyl phthalate was used in 30 weight parts but without dioctyl adiptate, by measuring their viscosities after one week of storage at ambient temperature and at 500 C.

The results are summarized below in Table 1.

TABLE 1

Sealant containing Sealant with Invented only tar as dioctyl phthal Sealant plasticizer ate alone Viscosity as manufactured 1500 2500 1800 (centipoise) Viscosity after 1 week of storage 1500 gelate in 2500 at ambient 3 days temperature (centipoise) Viscosity after 1 week of storage 1900 gelate in gelate in at 50-C. 3 hours 1 week (centipoise) The results show that the sealant according to the present invention which contains both dioctyl phthalate and dioctyl adipate is extremely stable.

OIL RESISTANCE PROPERTY TEST Seventy-five grams each of the sealant according to the present invention and and American product containing a coal tar mainly composed of a distillate boiling at over 3500C, were placed in vessels and immersed at 380C. for 48 hours in a solution of 70% isooctane and 30% toluene. After being lifted out of the solution they were dried and measured for weight loss.

The sealant of the present invention suffered a loss of 0.22%, which is considered to be negligible, whereas the American product suffered a loss of 1.03%.

As described above, the joint sealant according to the present invention excels in both stability and oil resistance.

Since the coal pitch blended with vinyl chloride resin is evenly distributed in the sealant, the sealant, when poured into the joint, makes a uniformly elastic bond. Since it becomes pourable by heating to a low temperature, the sealant suffers less thermal deterioration than the conventional sealant which takes a long time for heating to form a melt. Accordingly, it is simple and efficient to work.

COMPARATIVE EXAMPLE A stability test and oil resistance property test were carried out with respect to sealants prepared by a method similar to the manner of preparing the Embodiment except for using dioctyl phthalate and dibutyl phthalate separately instead of using dioctyl phthalate and dioctyl adipate together. These sealants were compared with the sealing according to the present invention.The results are shown in the following Table II: Table II

Sealant of Invention Sealants to be compared Joint use of dioctyl Containing Containing phthalate and dioctyl only dioctyl only dibutyl adipate adipate phthalate Sol stability (viscosity after 1 week 1500 cps 1900 cps gelate of storage at 50-C.) Reducing amount of oil resistance -7.5% -0.22% -0.9% (immersed for 48 hrs.) As is apparent from the results of the above test, the sealant containing only dioctyl adipate has good sol-stability.However, the s.p. (solubility parameter) value of dioctyl adipate is 8.6 and comes close to the s.p. value of jet fuel thus making the oil resistance property thereof extremely bad.

Therefore, it cannot be used as a sealant in places such as airfields, highways where the sealant is likely to be exposed to gasoline, jet fuel and the like.

According to the present invention, using dioctyl phthalate and dioctyl adipate together, a sealant having appropriate sol-stability and oil resistance is obtained with a s.p. value (8.9) of dioctyl phthalate and the sealant can be produced at low cost.

In case dibutyl phthalate (s.p. value: 9.4) having a higher s.p. value than dioctyl phthalate is used, the sealant becomes close to a s.p. value (9.6) of polyvinyl chloride, thus making sol-stabiiity thereof extremely bad and useless.

In this connection, "solubility parameter (s.p. value)" is property value of liquid, which becomes a measure for blendability between liquids. Liquids which have close s.p. values are apt tQ be dissolved each other. Action of solvent for high molecular substances can also be-represented by s.p. value. The measurement of s.p. value can be conducted by well known methods such as (1) evaporating energy method, (2) Hildebrand method using physical constant and (3) method for assuming s.p. value from molecular structure.

The following Table Ill shows s.p. values with respect to the typical examples of polymer, solvent and plasticizer: Table Ill

9 polyethylene 8.1 polystyrene 9.12 t polymethyl methacrylate 9.25 0 polyvinyl chloride 9.6 polyacrylonitrile 12.75 n-butane 6.6 n-octane 7.8 C toluene 8.9 > - acetone 9.8 ethanol 12.8 water 23.41 dioctyl adipate 8.6 dioctyl phthalate 8.9 N ,N s dibutyl phthalate 9.4 dimethyl phthalate 9.9 dimethyl phthalate 10.5 l

Claims

1. A concrete joint sealant composed of a coal tar mainly consisting of a distillate boiling at up to 35O0C.; vinyl chloride resin; coal pitch; and a mixture of dioctyl phthalate and dioctyl adipate as plasticizers.

2. A sealant according to Claim 1, wherein the compound ratio of dioctyl phthalate to dioctyl adipate is 19:1-4:1.

3. A sealant according to Claim 1 or 2, wherein the mixture of dioctyl phthalate and dioctyl adipate is 2040 weight % of the total weight of the sealant.

4. A sealant according to Claim 1 , 2 or 3, wherein the coal tar contains more than 50 weight % of the distillate boiling at up to 3500C.

5. A sealant according to any of claims 1 to 4, wherein the vinyl chloride resin is used as a paste resin.

6. A sealant according to any preceding claim, wherein the coal pitch has a melting point of 100-140 C.

7. A sealant according to any preceding claim, wherein the amount of coal tar is 10 10% by weight of the total weight of the sealant.

8. A sealant according to any preceding claim, wherein the amount of coal pitch is 515% by weight of the total weight of the sealant.

9. A sealant according to any preceding claim, wherein the amount of vinyl chloride resin is 225% by weight of the total weight of the sealant.

10. A sealant according to any preceding claim, including dibasic lead phosphite, to improve ageing resistance of the vinyl chloride resin.

11. A sealant according to any preceding claim, including a filler selected from the group consisting of calcium carbonate, talc and clay.

1 2. A concrete joint sealant substantially as described herein.

13. A process for manufacturing a concrete joint sealant comprising compounding a coal tar mainly composed of a distillate boiling up to 3500C., vinyl chloride resin, coal pitch and a mixture of dioctyl phthalate and dioctyl adipate.