JPS6129382B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to rubber-containing asphalt compositions with improved performance characterized by containing a modified low molecular weight polyisoprene rubber and a crosslinking agent thereof. Asphalt has long been widely used in fields such as roofing materials, sealants, adhesives, paints, road pavements, and waterway linings. Although asphalt is a material that is relatively inexpensive, has good high-temperature fluidity, and is easy to handle, it has poor strength characteristics, high temperature sensitivity, and poor low-temperature characteristics.
It has many drawbacks, including poor adhesion. Various methods have been proposed to improve these drawbacks by adding rubber-like substances to asphalt, and although some of these methods have actually been adopted, they are not always fully satisfactory. That is, for example, the method of mixing high molecular weight solid rubber with asphalt in advance using a kneader to create a masterbatch and adding it to asphalt requires an extra step of creating the masterbatch in advance, and High molecular weight solid rubber has poor solubility in asphalt, and therefore requires heating at high temperatures for long periods of time to dissolve it, which poses problems in workability. Since decomposition of the rubber causes denaturation such as gelation, a problem often arises in that the quality of the finished asphalt composition tends to vary. In addition, when natural rubber or high molecular weight solid polyisoprene rubber is used, the rubber molecules deteriorate rapidly, so in many cases it is necessary to add sulfur or sulfur compounds to crosslink the rubber molecules, which can lead to pollution and workplace problems. Nowadays, when environmental health regulations are becoming more and more stringent, sulfur compounds are not suitable for use. Among these, when natural rubber is exposed to high temperatures, a strong unpleasant odor is generated, probably due to non-rubber compounds present in natural rubber, which is a major problem. On the other hand, methods have been adopted to improve the performance of asphalt by adding latex-like rubber substances such as natural rubber latex or styrene-butadiene copolymer latex (SBR latex), but these methods vary depending on the latex used. This is problematic. In other words, when it comes to natural rubber latex, it has almost the same drawbacks as when using solid natural rubber.
In other words, it causes deterioration and product variation,
It also has the disadvantage of generating an unpleasant odor. Furthermore, SBR latex, which is currently used in large quantities to improve asphalt performance, gels during heating and mixing, which often causes problems during work. Moreover, when rubber is used in the latex state, the time required for dissolving it is generally shorter than when using solid rubber, which is an advantage, but it also takes time to evaporate the moisture that has entered the asphalt. In the field of adhesives, paints, etc., residual trace amounts of moisture may cause problems, and are not always completely satisfactory. In view of the above-mentioned problems, the inventors of the present invention have made extensive studies to obtain asphalt compositions with excellent properties such as dissolution workability, mechanical strength characteristics, and adhesive properties. As a component and its auxiliary component, cis-1,
4 Modified low molecular weight polyisoprene rubber having a bond content of 70% or more and a molecular weight of 13,000 to 90,000 with 0.03 to 12 moles of maleic anhydride or a derivative thereof added per 100 moles of isoprene monomer units of the low molecular weight rubber. The inventors have discovered that an asphalt composition suitable for the intended purpose can be obtained by using rubber and its crosslinking agent, and have completed the present invention. The modified low molecular weight rubber used in the present invention is a maleic anhydride adduct () obtained by reacting a low molecular weight polyisoprene rubber having a specific structure with maleic anhydride, and a maleic anhydride adduct () obtained by reacting a low molecular weight polyisoprene rubber having a specific structure with maleic anhydride. Alcohols such as methanol, ethanol, n-butanol, isopropanol or ammonia, for example in the presence or absence of a catalyst,
One or both carboxyl groups formed by maleic anhydride into an ester by reacting with amines such as n-propylamine, n-butylamine, and ethanolamine (-a), amidation (-b), Imidized (-c),
Alternatively, the acid anhydride group of maleic anhydride is hydrolyzed to form a free carboxyl group (-
d), and esterification or amidation of maleic acid or maleic anhydride, or addition of a maleic anhydride derivative such as maleimide to a low molecular weight polyisoprene rubber (). Among them, from the viewpoint of viscosity stability when the modified low molecular weight polyisoprene rubber is stored for a long period of time, modified low molecular weight polyisoprene rubber to which an alcohol derivative or an amine compound derivative of maleic anhydride is added is preferred. The reaction for adding maleic anhydride or its derivative to low molecular weight polyisoprene rubber is, for example, as follows. That is, by adding maleic anhydride or a derivative thereof to a solution of a specific low molecular weight polyisoprene rubber or a low molecular weight polyisoprene rubber in the absence of a solvent, and causing a heating reaction in the presence or absence of a radical catalyst. A modified low molecular weight polyisoprene rubber to which maleic anhydride or a derivative thereof is added is obtained. The solvent used here generally includes hydrocarbons, halogenated hydrocarbons, etc., but n-butane, n-
- Inert solvents such as hexane, n-heptane, cyclohexane, benzene, toluene, and xylene are more preferred. The amount of maleic anhydride or its derivative added in this modified low molecular weight polyisoprene rubber affects the solubility of the modified low molecular weight polyisoprene rubber in asphalt and the performance of the asphalt composition finally obtained. Isoprene monomer unit of low molecular weight polyisoprene rubber 100
It should range from 0.03 to 12 mol, preferably from 0.1 to 8 mol %. If the amount added is too small, the effect of improving various properties such as mechanical strength and adhesion of the final asphalt composition will be small, and if the amount added is too large, the modified low molecular weight polyisoprene rubber will not be able to improve the asphalt composition. The solubility deteriorates, making it impossible to obtain a practical product. Low molecular weight polyisoprene rubber before addition of maleic anhydride or its derivatives can be obtained by polymerizing isoprene monomers by anionic polymerization, radical polymerization, coordination anionic polymerization, etc. It can also be obtained by thermally decomposing natural rubber or solid synthetic cis-1,4-polyisoprene rubber obtained by Ziegler polymerization or anionic polymerization at high temperatures (e.g. 180-300°C). . However, low molecular weight polyisoprene rubber obtained by thermal decomposition has an extremely strong odor due to substances produced as by-products during thermal decomposition, and furthermore, it is difficult to make the quality uniform, so it is not preferable. In particular, low molecular weight polyisoprene rubber made from decomposed natural rubber has a strong unpleasant odor when dissolved in asphalt at high temperatures. Therefore, the low molecular weight polyisoprene rubber used in the present invention is preferably one obtained by a polymerization method, especially an anionic polymerization method using a lithium-based catalyst that does not produce gel during polymerization and has a large number of cis-1.4 structures. Most preferred are low molecular weight polyisoprene rubbers. It should be noted that a small amount of monomers other than isoprene may be polymerized as long as the spirit of the present invention is not impaired. The amount of cis-1,4 bonds in the low molecular weight polyisoprene rubber used for modification is 70% or more, preferably 80% or more.
Must be greater than or equal to %. If the ratio of the amount of cis-1,4 bonds is too low, the performance of the obtained asphalt composition itself will be poor, and gels may be formed when the asphalt is dissolved. In addition, the molecular weight of low molecular weight polyisoprene rubber before modification is
Must be in the range 13000-90000. If the molecular weight is too low, the resulting asphalt composition will not have sufficient performance, and if the molecular weight is too high, the solubility in asphalt will be poor, making it impractical.
In addition, the molecular weight as used in the present invention refers to the viscosity average molecular weight (M), which is determined by the following formula using the intrinsic viscosity [η] measured in a toluene solution at 30°C. [η] = 1.21×10 ^-4 M ^0.77 Also, as the crosslinking agent for the modified low molecular weight polyisoprene rubber, which is another important component used in the present invention, metal crosslinking agents, amine crosslinking agents, epoxy One or more selected from a crosslinking agent, a glycol crosslinking agent, and an isocyanate crosslinking agent are used. Metallic crosslinking agents are compounds of metals belonging to Groups 1, 2, and 4 of the periodic table, such as potassium acetate, sodium hydroxide, sodium carbonate, zinc oxide (zinc white), magnesium oxide, Lead oxide, calcium chloride, calcium hydroxide, aluminum hydroxide, zinc acetate, calcium acetate, zinc resinate,
These include sodium resinate and calcium resinate.
Examples of amine-based crosslinking agents include diethylenetriamine, triethylenetetramine, diaminodiphenylmethane, polyethyleneimine, aziridenyl compounds, and polyamide resins. A typical example of the epoxy crosslinking agent is an epoxy resin obtained by condensation of bisphenol A or bisphenol F with epichlorohydrin, and its epoxy equivalent is preferably about 150 to 700. Examples of glycol-based crosslinking agents include polyoxyethylene glycol, polyoxypropylene glycol, and esterified products thereof. The isocyanate-based crosslinking agent is a compound having two or more isocyanate groups in the molecule, such as tolylene diisocyanate, phenylene diisocyanate, and diphenylmethane diisocyanate. Of course, conventional sulfur crosslinking, that is, vulcanization, using the isoprene double bonds of modified low molecular weight polyisoprene rubber is also possible, but this is not preferable in terms of odor and crosslinking efficiency, and as in the present invention, A crosslinking method that utilizes a functional group added to modified low molecular weight polyisoprene rubber is preferred. The amount of the crosslinking agent used is 0.1 to 200 parts by weight, preferably 0.5 to 50 parts by weight, based on 100 parts by weight of the modified low molecular weight polyisoprene rubber. In the present invention, asphalt refers to natural asphalt,
and petroleum-based asphalt such as straight asphalt, semi-blown asphalt, and blown asphalt. These asphalts may be used in combination. Incidentally, bituminous substances such as tar and pitch may be added. The ratio of asphalt to modified low molecular weight polyisoprene rubber is generally 99/1 (asphalt)/(modified low molecular weight polyisoprene rubber) by weight.
~20/80. Especially in the field of road paving, from January to July 1999.
It is preferably used in the range of 0/30, and in the field of sealants and adhesives, it is preferably used in the range of 95/5 to 40/60. In addition to the essential asphalt, modified low molecular weight polyisoprene rubber, and its crosslinking agent, the asphalt composition of the present invention may optionally include fillers such as carbon black, clay, silica, calcium carbonate, lime, and mica, sand, gravel, etc. Aggregates such as crushed stone,
Asbestos, fibers such as glass fibers, synthetic fibers, mineral oil, vegetable oil, unmodified low molecular weight polyisoprene rubber, liquid polybutadiene, oxidative deterioration inhibitors, tackifying resins, antifoaming agents, and in some cases small amounts It contains a solvent and the like. Further, a small amount of high molecular weight solid rubber, rubber latex, thermoplastic rubber, thermoplastic resin, etc. may be contained as long as the spirit of the present invention is not impaired. The composition of the present invention is produced using a mixer such as a tank mixer, a kneader, or a roll mill. The asphalt composition of the present invention is useful in a wide range of fields such as road paving, waterway lining, sealing materials, roofing materials, adhesives, paints, vibration-proofing materials, and sound-proofing materials. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto. Example 1 and Comparative Example 1 The amount of cis-1,4 bonds obtained by a polymerization method using a lithium catalyst was 85% and the molecular weight was
61,000 and maleic anhydride at 150°C, maleic anhydride is converted into 0.01 mol, 1.2 mol and 1.2 mol per 100 mol of isoprene monomer units of the low molecular weight polyisoprene rubber, respectively. Modified low molecular weight polyisoprene rubbers (A, B and C) with 17.1 mol added were obtained. Straight asphalt (penetration 80
-100) Adding 3 parts by weight of each of the above three types of modified low molecular weight polyisoprene rubber to 100 parts by weight,
The mixture was stirred and mixed at 160°C for 25 minutes, and then 2 parts by weight of each calcium-modified rosin resin having a softening point of 120°C was added as a crosslinking agent, and the mixture was further stirred for 5 minutes.
When using modified low molecular weight polyisoprene rubber A with an added amount of maleic anhydride of 0.01 mol and modified low molecular weight polyisoprene rubber B with the same amount of 1.2 mol, the rubber-containing asphalt was uniformly dissolved by stirring for 30 minutes. Although a composition was obtained, a uniform rubber-containing asphalt composition could not be obtained when modified low molecular weight polyisoprene rubber C with a high added amount of maleic anhydride of 17.1 moles was used.
The strength performance of the above rubber-containing asphalt compositions using modified low molecular weight polyisoprene rubbers A and B was evaluated using toughness values and tenacity values according to the Benson method. Also each asphalt composition 145
The viscosity at °C was investigated. The results are shown in Table 1. Comparative Example 2 Commercially available natural rubber latex with solid content of 61.5% and styrene content of 25% with solid content of 52.0%.
Each SBR latex was added to 100 parts by weight of asphalt in an amount of 5 parts by weight, and mixed and stirred for 30 minutes under the same conditions as in Example 1. However, when the latex was added, foaming was intense due to evaporation of water, and not only was the addition process time-consuming, but a uniformly dissolved rubber-containing asphalt composition could not be obtained within a mixing time of 30 minutes. Therefore, in order to measure the strength performance, a rubber-containing asphalt composition was prepared with stirring and mixing time of 70 minutes, and the composition was subjected to measurement. The result is the first
Shown in the table.

[Table] As can be seen from Table 1, the strength performance of the asphalt composition made using modified low molecular weight polyisoprene rubber B in which the amount of maleic anhydride added falls within the range of the present invention is superior to that of straight asphalt itself. It was also significantly improved, and was superior to asphalt compositions using natural rubber latex or SBR latex. Example 2 and Comparative Example 3 Polyisoprene rubbers having molecular weights of 5,200, 37,000, and 210,000, respectively, were obtained by a polymerization method using a lithium catalyst. The amount of cis-1,4 bonds is all
It was over 75%. By heating and reacting each of these three types of polyisoprene rubber with maleic anhydride at 150°C, maleic anhydride becomes approximately
Modified polyisoprene rubber D, E with 0.7 mol added
and F were obtained. Example 1 was carried out by adding 10 parts by weight of each of the above three types of modified polyisoprene rubber to 100 parts by weight of straight asphalt (penetration 80-100), and further using 3 parts by weight of calcium-modified rosin resin as a crosslinking agent. A dissolution operation was performed using the same procedure. Modified low molecular weight polyisoprene rubber D obtained by adding maleic anhydride to low molecular weight polyisoprene with a molecular weight of 5200 and modified low molecular weight polyisoprene rubber D obtained by adding maleic anhydride to low molecular weight polyisoprene having a molecular weight of 37000 by stirring and mixing for 30 minutes. When Rubber E was used, a uniform rubber-containing asphalt composition was obtained, but when polyisoprene rubber F, whose molecular weight was 210,000, which was larger than the molecular weight specified in the present invention, was used, a uniform rubber-containing asphalt composition was obtained. I couldn't get anything. When the strength performance of rubber-containing asphalt compositions using modified low-molecular-weight polyisoprene rubbers D and E was measured, it was found that maleic anhydride addition of low-molecular-weight polyisoprene rubber with a molecular weight of 5200, which is smaller than the molecular weight specified in the present invention. Regarding rubber-containing asphalt compositions using modified low molecular weight polyisoprene rubber D, the degree of improvement in toughness and tenacity was small; however, when using modified low molecular weight polyisoprene rubber E within the scope of the present invention, If it was, the toughness would be 87.2Kg.
-cm, tenacity was 21.5Kg-cm, and had excellent strength performance. Example 3 The modified low molecular weight polyisoprene rubber B used in Example 1 was coated with straight asphalt (penetration 80-
100) Add 5 parts by weight to 100 parts by weight and heat at 170℃ for 20
After stirring and mixing for a minute, 5 parts of calcium chloride was added in the form of an aqueous solution, and stirring and mixing was continued for 15 minutes to obtain a rubber-containing asphalt composition. The toughness of this rubber-containing asphalt composition was 59.9 kg-cm, the tenacity was 22.7 kg-cm, and it had excellent performance. Example 4 and Comparative Example 4 Molecular weight obtained by polymerization method using lithium catalyst is 47000 and cis-1,4 bond content is 82%
By reacting the low molecular weight polyisoprene rubber with maleic anhydride (at 200°C), a modified polyisoprene rubber G to which 1.5 mol% of maleic anhydride was added was obtained. This modified polyisoprene rubber G
By heating and mixing with ethanol, a modified low molecular weight polyisoprene rubber H in which the added maleic anhydride was half-esterified was obtained. 2 mentioned above
Modified low molecular weight polyisoprene rubber G and H, straight asphalt (penetration 80-100),
A rubber-containing asphalt composition was obtained according to the method of Example 1 according to the formulation shown in Table 2 using a zinc-modified rosin resin (softening point, 135° C.) as a crosslinking agent. The composition was coated on a polyester film to a thickness of about 30 microns to prepare a tape-like adhesive, and its adhesive strength to stainless steel plates and glass plates was evaluated by a 180° peel test method (Table 2).

[Table] As is clear from Table 2, the rubber-containing asphalt composition of the present invention has excellent adhesive strength. Example 5 and Comparative Example 5 Modification in which 0.5 mole of maleic anhydride was added to a low molecular weight polyisoprene rubber with a molecular weight of 78,000 and a cis-1,4 bond content of 85% obtained by a polymerization method using a lithium catalyst. A low molecular weight polyisoprene rubber I was prepared. Adding 6 parts by weight of the above modified low molecular weight polyisoprene rubber I to 100 parts by weight of straight asphalt (penetration 80-100),
After stirring and mixing at 165°C for 20 minutes, 1 part by weight of tetraethylenepentamine was added as a crosslinking agent, and
The mixture was stirred and mixed for a minute to obtain an asphalt composition containing modified low molecular weight polyisoprene rubber. The toughness of this asphalt composition was 92.0 kg-cm, and the tenacity was 41.2 kg-cm. Further, 100 parts by weight of clay was mixed with 100 parts by weight of straight asphalt and 100 parts by weight of the above asphalt composition,
When each mixture was applied to a glass plate with a thickness of 1 cm and an area of 4 cm ² and the glass plate was stood at an angle of 60° and left for 48 hours, it was noticeable that the mixture made of straight asphalt and clay was denatured. The asphalt composition of the present invention, consisting of low molecular weight polyisoprene I, crosslinker, straight asphalt and clay, was hardly noticeable. Comparative Example 6 Maleic anhydride was added to a low molecular weight polyisoprene with a molecular weight of 72,000 and a cis-1,4 bond content of 41% obtained by an anionic polymerization method in the presence of an ether compound to add 1.5 moles of maleic anhydride. A modified low molecular weight polyisoprene was obtained. 6 parts by weight of the modified low molecular weight polyisoprene whose cis-1,4 bond amount is outside the range specified in the present invention was added to 100 parts by weight of straight asphalt and heated at 170℃ for 30 minutes.
Although stirring and mixing was attempted for several minutes, a uniform asphalt composition could not be obtained. Further stirring and mixing time 30
Although the time was increased for a longer time, a uniform asphalt composition was still not obtained.

Claims (1)

[Claims] 1 The amount of cis-1,4 bonds is 70% or more and the molecular weight is
13,000 to 90,000 per 100 moles of isoprene monomer unit of the low molecular weight rubber.
A rubber-containing asphalt composition comprising a modified low molecular weight rubber added with 0.03 to 12 moles and a crosslinking agent thereof.