JP2577607B2 - Waterproof sheet excellent in flexibility and method for producing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an asphalt-based waterproof sheet excellent in flexibility at low temperatures and excellent in cohesion properties having a high softening point.

[Conventional technology]

Conventionally, asphalt-based waterproof sheets have been used by adding various polymers to blown asphalt or straight asphalt, and studies have been made to use materials that meet higher required characteristics.

Specific examples of the polymer include an ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate, rubber latex, and a block copolymer composed of a conjugated diene and a vinyl aromatic hydrocarbon.

[Problems to be solved by the invention]

However, an asphalt composition obtained by adding an ethylene-vinyl acetate copolymer or ethylene-ethyl acrylate to asphalt is inferior in low-temperature characteristics and is not preferable because cracks and the like occur in winter.

On the other hand, asphalt compositions to which a conventional block copolymer comprising a conjugated diene and a vinyl aromatic hydrocarbon are added have excellent low-temperature properties, and have a low elastic modulus and are excellent in workability when formed into a waterproof sheet. However, cohesion may be insufficient. For this reason, attempts have been made to improve the molecular weight of the block copolymer by increasing the molecular weight. However, on the other hand, the melt viscosity increases and the processability is significantly sacrificed.

In addition, when using blown asphalt alone, although the softening point is high and preferable, the flexibility at low temperature is inferior.
Cracks are likely to occur.

As described above, the conventional asphalt composition or blown asphalt to which each polymer is added can simultaneously satisfy the necessary softening point, flexibility at low temperature, high balance of cohesive force properties and workability. Has not existed.

[Means and actions for solving the problem]

In view of the current situation, the present inventors have found that the softening point, flexibility at low temperature, cohesive force properties and processability of an asphalt composition containing a thermoplastic elastomer made of butadiene and styrene, a petroleum softener and asphalt are blended. As a result of intensive studies on improvements, the present invention has been accomplished.

 That is, the present invention is as follows.

(1) (a) A styrene-butadiene-based thermoplastic elastic material having a bound styrene content of 25 to 45% by weight and a weight average molecular weight of 150,000 or more is 15% by weight or more. (B) Viscosity (measuring temperature 98.9 ° C) 3 to 10 centistokes 4 to 10 petroleum softeners with a viscosity specific gravity constant of 0.810 to 0.900
% By weight (c) asphalt is 81% by weight or less, and the dispersion of the styrene-butadiene-based thermoplastic elastic material is a composition having a network structure in which a continuous phase is formed in the composition. A waterproof sheet with excellent flexibility.

(2) The amount of bound styrene within the particle size range of 0.01 to 1 mm 25
A styrene-butadiene-based thermoplastic elastic material having a weight average molecular weight of 150,000 or more is divided into two or more portions at a viscosity of 170 to 220 ° C. (measured at a temperature of 9 to 90%).
8.9 ° C) 3-10 centistokes, viscosity specific gravity constant 0.810-
2. The method for producing a waterproof sheet having excellent flexibility according to claim 1, wherein the water-resistant sheet is put together with a petroleum softener of 0.900 and kneaded.

 Hereinafter, the present invention will be described in detail.

The styrene-butadiene-based thermoplastic elastic material used in the present invention is a block copolymer composed of a styrene polymer block and a butadiene polymer block. This polymer is characterized in that the block copolymer has a styrene content of 25 to 45% by weight, preferably 25 to 35% by weight, which is usually used as a styrene-butadiene-based thermoplastic elastic material, and has a weight average molecular weight. Is a block copolymer of 150,000 or more. If the styrene content of the block copolymer is less than 25% by weight, the asphalt composition has poor cohesive strength properties, and if it exceeds 45% by weight, flexibility at low temperatures is poor. When the weight average molecular weight is less than 150,000, the softening point and the cohesive strength are poor.

In the present invention, the polymer structure is represented by a general formula: (AB) _n , AB-A) _n , BA-B) _n ( _where A is a styrene polymer block,
B is a butadiene polymer block. A block and B
The boundaries with the blocks need not be clearly distinguished. N is an integer of 1 or more. ) Is preferred.

The petroleum softener used in the present invention is an oil contained in a high-boiling fraction of petroleum used in general rubber compounding, and has a viscosity (measuring temperature of 98.9 ° C.) of 3 to 10 centistokes and a viscosity of 3 to 10 centistokes. The specific gravity constant is 0.810 to 0.900. If the viscosity is less than 3 centistokes, the softening point and cohesive strength of the asphalt composition tend to decrease, and if the viscosity exceeds 10 centistokes, the flexibility at low temperatures decreases. When the viscosity specific gravity constant is less than 0.810, the softening point and cohesive strength of the asphalt composition decrease, and when it exceeds 0.900, the flexibility decreases.

In the present invention, the petroleum softener is used in the range of 4 to 10% by weight, preferably 6 to 8% by weight based on the asphalt blend. If the blending amount of the petroleum softening agent is less than 4% by weight, the dispersion state of the thermoplastic elastomer in the asphalt does not form a network structure, and the elasticity is poor. If it exceeds 10% by weight, the softening point and the cohesive strength of the asphalt composition are inferior.
These petroleum-based softeners may be added to the polymer in advance, or may be added separately from the polymer when charged into asphalt, either of which is possible.

The network structure referred to here indicates whether or not the thermoplastic elastomer has a network structure forming a continuous phase in the blend by observing the asphalt composition with an electron microscope. When it does not have a structure, it is inferior in flexibility.
As a preferred size of the network structure for maintaining flexibility, for example, the length of the major axis of the island-shaped asphalt surrounded by the styrene-butadiene-based thermoplastic elastic material is 10 μm or less.

The asphalt used in the present invention is a common petroleum asphalt obtained by distillation from petroleum. The thermoplastic elastic material used in the present invention is pulverized to a particle size of 0.01 to 1 mm, and is used in an amount of 15% by weight or more, preferably 20% by weight or more based on the asphalt composition. As used herein, the particle size is defined as follows: 0.3 g of a crushed product is evenly distributed on 24 mm x 24 mm black paper, photographed at a magnification of 6 times using a stereoscopic microscope, and an image analysis device (PIAS Was used to measure the particle size. Therefore, when the particle size is less than 0.01 mm, when injected into asphalt, the thermoplastic elastic body is scattered and the workability is poor, and when it exceeds 1 mm, the solubility at the time of compounding is poor,
It takes a long time to completely dissolve. If the content of the thermoplastic elastomer is less than 15% by weight, the thermoplastic elastomer does not have a sufficient network structure in the composition, so that the asphalt is not sufficiently modified, and the softening point, flexibility, cohesive strength, etc. Poor characteristics. In addition, as a kneading method, the thermoplastic elastic body is charged in two or more portions, and the asphalt temperature is set to 170 ° C to 220 ° C. When the thermoplastic elastic body is put in once, the thermoplastic elastic body floats on the asphalt liquid surface and tends to be solidified, which requires a kneading time. If the temperature of the asphalt is lower than 170 ° C., the melt viscosity increases, the workability is deteriorated, and the dispersion of the thermoplastic elastomer in the asphalt does not form a network structure after kneading. As a result, the flexibility is particularly poor. On the other hand, when the temperature exceeds 220 ° C., the thermoplastic elastic body is not preferable because it is deteriorated by heat. Further, as the kneading device, a device in which a stirring device such as a stirring motor and a homomixer is installed in a dissolving tank generally used for asphalt, or a kneader can be used.

〔Example〕

Examples are shown below, which are representative of the present invention, and do not limit the scope of the present invention.

The melt viscosity was measured using a rotational viscometer by immersing a container filled with the asphalt composition in a 180 ° C. oil bath.

According to JIS K2207, the softening point was filled with the sample in a prescribed ring, horizontally supported in a water bath, a 3.5 g ball was placed in the center of the sample, and the bath temperature was raised at a rate of 5 ° C./min. At that time, the temperature when the sample touched the bottom plate of the ring base was measured by the weight of the ball.

According to JIS K6301, the cohesive force characteristics are as follows.
A dumbbell-shaped sheet was punched out, and the dumbbell-shaped sheet was pulled at a pulling speed of 500 mm / min. The relationship between stress and elongation at that time was examined, and the stress and elongation at break were measured.

Flexibility, the asphalt composition, 180 ° C. press, to produce a 3 mm thick sheet, sheet size 20 mm × 1
Cut out to 00mm, immersed in dry ice-ethanol solution for 10 minutes or more, take out the sheet,
The sheet was wound around a 15 mm metal rod so that the longitudinal direction of the sheet was bent, and the lowest temperature at which the sheet did not crack was measured.

For the network structure, a 2 mm thick sheet was prepared by pressing the asphalt composition at 180 ° C, the sheet was treated with osmium acid, and the cross section of the sheet was thinly cut with a microtome and observed with an electron microscope. A photograph was taken, and it was visually determined from the photograph whether the thermoplastic elastomer had a network structure forming a continuous phase in the composition.

Examples 1 to 3 and Comparative Examples 1 to 3 20% by weight of the styrene-butadiene-based thermoplastic elastomer shown in Table 1 with respect to the asphalt blend, and a petroleum softener also shown in Table 1 [viscosity 7.1 centistokes (Cst) (measurement temperature 98.9 ° C), viscosity specific gravity constant 0.84, sonic process oil R-200, manufactured by Kyodo Petroleum Co., Ltd. The styrene-butadiene-based thermoplastic elastic material was used, and a crusher (manufactured by Torai Iron Works) was used.
A 粉 砕 0.8 mm ground product was obtained. Asphalt (Storus 60-80, manufactured by Maruzen Petroleum Co., Ltd.) being stirred at 5000 rpm with a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) at a temperature of 180 ° C. as the styrene-butadiene-based thermoplastic elastic material conversion amount, 20
10% by weight first, 5% by weight after 10 minutes, and 10%
After 5 minutes, 5% by weight was added, followed by stirring for 60 minutes to prepare a composition of asphalt and a styrene-butadiene-based thermoplastic elastic body containing a petroleum-based softening agent.

The performance of the asphalt composition thus produced was evaluated for the above items.

Example 2 was the same as Example 1 except that the type of the petroleum-based softener was changed, and the petroleum-based softener and the styrene-butadiene-based thermoplastic elastomer were separately charged into asphalt and the asphalt temperature was changed. An asphalt composition was prepared in the same manner, and its performance was evaluated.

In Example 3, an asphalt composition was prepared in the same manner as in Example 1 except that the type and input amount of the styrene-butadiene-based thermoplastic elastic material, the type of the petroleum-based softening agent, and the asphalt temperature were changed, and the performance was evaluated. Was evaluated.

Comparative Example 1 was carried out except that the molecular weight of the styrene-butadiene-based thermoplastic elastic material was changed, Comparative Examples 2 and 4 were different types of petroleum softener, and Comparative Example 3 was different except that the type of petroleum softener and asphalt temperature were changed. An asphalt composition was prepared in the same manner as in Example 1, and its performance was evaluated.

The results are shown in Table 1. The asphalt composition produced by the method specified in the present invention using the styrene-butadiene-based thermoplastic elastic material and the petroleum-based softener specified in the present invention is a thermoplastic elastomer. It can be seen that the body has a network structure and exhibits excellent softening point, flexibility and cohesion properties as a waterproof sheet.

FIG. 1 shows a schematic view of an electron micrograph of a cross section of the waterproof sheet obtained in Example 1. The black part of the mimetic diagram of the electron micrograph shows a styrene-butadiene-based thermoplastic elastic material, and the white part shows asphalt. The petroleum softener is contained in the thermoplastic elastic body and belongs to a black part. As is apparent from the electron micrograph, the styrene-butadiene-based thermoplastic elastic body 1 has a uniform network structure. 2 indicates asphalt. An asphalt composition was prepared in the same manner as in Example 1 except that the kneading method was performed by a kneader (manufactured by Moriyama Seisakusho), and the performance was evaluated. As a result, the same result as in Example 1 was obtained.

Examples 4 and 5 and Comparative Examples 4 to 10 In Example 4, the injection amount and asphalt temperature of the styrene-butadiene-based thermoplastic elastic material were used.
Particle size of butadiene-based thermoplastic elastic body and the method of introduction and the type of petroleum-based softener, Comparative Examples 4 and 5 are the input amounts of petroleum-based softener,
Comparative Example 6 has a particle diameter of a styrene-butadiene-based thermoplastic elastic material, Comparative Example 7 has a method of charging a styrene-butadiene-based thermoplastic elastic material, Comparative Example 8 has a charged amount of a styrene-butadiene-based thermoplastic elastic material, and a comparative example. In Examples 9 and 10, asphalt compositions were prepared in the same manner as in Example 1 except that the asphalt temperature was changed, and the performance was evaluated.

The results are shown in Table 2. The content of the petroleum-based softener specified in the present invention, the particle size of the styrene-butadiene-based thermoplastic elastic body containing the petroleum-based softener, the input amount of the pulverized product, the input method, and It can be seen that the asphalt composition prepared at the asphalt temperature shows good properties.

FIGS. 2 and 3 show simulated views of electron micrographs of cross sections of the waterproof sheets obtained in Comparative Examples 8 and 9, respectively. As is apparent from the electron micrograph, the styrene-butadiene-based thermoplastic elastic body 1 does not show a uniform network structure.

〔The invention's effect〕

The waterproofing sheet of the present invention is particularly excellent in flexibility and also excellent in softening point, cohesive strength and workability.

[Brief description of the drawings]

FIG. 1 is an electron micrograph of a cross section of an asphaltic waterproof sheet of the present invention, and FIGS. 2 and 3 are electron micrographs of comparative examples.

Claims (2)

(57) [Claims] (A) A styrene-butadiene-based thermoplastic elastic material having a bound styrene content of 25 to 45% by weight and a weight average molecular weight of 150,000 or more is 15% by weight or more. (B) Viscosity (measuring temperature 98.9 ° C.) 3 to 10 Centistokes, 4 to 10 petroleum-based softeners having a viscosity specific gravity constant of 0.810 to 0.900
% By weight (c) asphalt is 81% by weight or less, and the dispersion of the styrene-butadiene-based thermoplastic elastic material is a composition having a network structure in which a continuous phase is formed in the composition. A waterproof sheet with excellent flexibility. 2. A styrene-butadiene-based thermoplastic elastic material having a bound styrene content of 25 to 45% by weight and a weight average molecular weight of 150,000 or more in a particle size range of 0.01 to 1 mm is divided into two or more portions at 170 ° C. Viscosity in asphalt at 220 ° C (measurement temperature
98.9 ° C) 3-10 centistokes, viscosity specific gravity constant 0.810
2. The method for producing a waterproof sheet having excellent flexibility according to claim 1, wherein the water-resistant sheet is charged together with a petroleum softening agent of ~ 0.900 and kneaded.