JPS6031327B2 - Method for producing low molecular weight polydiene rubber aqueous emulsion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing an aqueous emulsion of a low molecular weight polylene rubber, and more particularly to a method for producing an aqueous emulsion of a low molecular weight polygene rubber for improving rubber latex.

Aqueous emulsions of low-molecular-weight polyene rubbers, especially low-molecular-weight polyisoprene rubbers, that have appeared in recent years have been used as additives to latex adhesives to increase their unvulcanized tackiness, foam rubbers, balloons, gloves, and medical applications. It is added to latex during the manufacture of latex products such as sanitary products, and has a remarkable effect as a modifier, improving the flexibility of the product.

Such low molecular weight polyisoprene rubber aqueous emulsions are conventionally prepared using, for example, oleic acid soap, polyoxyethylene alkyl ether ammonium sulfate, combinations thereof, or polyoxyethylene alkyl (allyl) ether phosphate as emulsifiers. It has the advantage of being excellent in terms of stability, miscibility with solid rubber latex, and co-adherability. Among them, a low molecular weight polyisoprene rubber aqueous emulsion which is emulsified using polyoxyethylene alkyl (allyl) ether phosphate as an emulsifier, which is described in Tokoseki Sho 54-12404 No. 1, is particularly effective in terms of stability. It is excellent. However, when the aqueous emulsion obtained by the conventional method described above is blended with solid rubber latex such as natural rubber and then molded into a vulcanized sheet, crater-like avatars occur on the surface of the vulcanized sheet. This has the following problems. This crater-shaped avatar is
It is negligible in thick products and applications where relatively thick layers are used, such as adhesives, but in thin products, such as balloons, sanitary products, or surgical gloves, where strictly uniform layers are used, it is negligible. This is a particularly serious problem when a vulcanized sheet with a vulcanized surface is required. The present inventors have made efforts to obtain a low molecular weight polydiene rubber aqueous emulsion that can prevent the occurrence of crater-like avatars in thin products obtained from the above-mentioned latex, and in particular, to obtain a low molecular weight polydiene rubber aqueous emulsion for use in solid rubber latex waste. After further investigation, we found that by emulsifying a low molecular weight polyene rubber in the presence of a water-soluble polymer with functional groups based on polyoxyethylene alkyl (allyl) ether phosphate and maleisic anhydride, we were able to reduce the conventional low molecular weight A low molecular weight polygene rubber aqueous emulsion that can prevent the formation of crater-like avatars on the product surface, which is especially required for thin products, without impairing the excellent manufacturing method and performance of the polygene rubber aqueous emulsion, especially for modifying solid rubber latex. It was discovered that an aqueous emulsion of low molecular weight polyene rubber can be obtained, and the present invention was completed.

In particular, low molecular weight polyisoprene rubber or poly(in-prene-butadiene) rubber having 35% or less vinyl bonds and a molecular weight in the range of 10,000 to 60,000 is used as the low molecular weight polyene rubber, and a functional group based on maleic anhydride is used. Particularly remarkable effects are observed when a reaction product of isobutylene-maleic anhydride copolymer and ammonia is used as the lagoonal polymer having the following properties.
Note that such effects can be obtained when the emulsifier and the water-soluble polymer having a functional group based on maleic anhydride are used alone to form an emulsion, or when they are later added to the emulsion, the emulsifier appears to be and a water-soluble polymer having a functional group based on maleic anhydride, which is not exhibited when the water-soluble polymer has a functional group based on the emulsifier and maleic anhydride. It is a unique phenomenon that occurs only when a polymer is used in combination to form an emulsion. The low molecular weight polydiene rubber used in the present invention has a vinyl bond content of 35% or less,
Preferably 25% or less, and the molecular weight is 10,000
-100,000, preferably from 20,000 to 60,000.

Examples include polymer rubbers of conjugated gene compounds such as rene, piberylene, hexadiene or chlorobrene, or copolymer rubbers thereof. The vinyl bond amount is evaluated by infrared absorption spectrum, and the molecular weight means viscosity average molecular weight (Mv), which is expressed by the formula using the intrinsic viscosity ([ri]) measured at 30°C in toluene. =L21×
10-4M〆. 77, but
If these values deviate from the above range, it may become difficult to form an emulsion, requiring a significantly large amount of solvent, or the aqueous emulsion obtained by emulsion may be blended with solid rubber latex and molded. When subjected to heat treatment, it becomes difficult to co-vulcanize with the solid rubber, resulting in a significant decrease in the physical properties of the molded product, and the improvement of flexibility is no longer observed, thus losing the advantage of using low molecular weight polylene rubber. It will become. The above-mentioned low molecular weight polyester rubber is
The above-mentioned conjugated diene compound can be produced by various known polymerization methods such as anionic polymerization using a lithium catalyst and coordination anionic polymerization using a Ziegler catalyst, or a method of thermally decomposing solid rubber to obtain a predetermined molecular weight. However, there is a method in which polymerization is carried out in the presence or absence of a solvent using a lithium-based catalyst because it is easy to control the polymerization, it is easy to generate the aforementioned microwire structure, and it does not contain impurities. Most preferably adopted. In this way, low molecular weight polylene rubbers are produced, and among them, low molecular weight isoprene rubbers, such as low molecular weight polyisoprene rubber and low molecular weight poly(isoprene-butanene) rubber, are particularly suitable for the cis-1,4 bond. Results most consistent with the intended objectives of the present invention are obtained when using low molecular weight polyisoprene rubber in an amount of 65% or more, preferably 75% or more. It should be noted that these low molecular weight polyene rubbers may have functional groups such as hydroxyl groups, halogen groups or maleic anhydride groups introduced into their molecules as long as the gist of the present invention is not impaired.

The polyoxyethylene alkyl (allyl) ether phosphate used as an emulsifier in the present invention is an organic phosphate ester represented by the general formula shown below, and is a nonionic anionic surfactant. .

or here R is an alkyl group having 8 to 18 carbon atoms, or an alkylaryl group having 8 to 12 carbon atoms in the alkyl group, and n indicates the average number of moles of ethylene oxide added, and here 3
~30 integer.

A typical example of the preferred one is polyoxyethylene nonylphenyl phosphate. The use of such an emulsifier provides a low molecular weight polygene aqueous emulsion that exhibits less foaming during emulsion production, has uniform and small particle diameters, and has excellent storage stability as well as mechanical stability. Incidentally, since such emulsifiers are water-soluble and exhibit strong acidity, they can be used by appropriately adjusting the pH' using an alkaline reagent such as caustic soda, caustic potash, or amine, depending on the purpose.

Changing the pH does not pose much of a problem, but if the pH is too high, bubbles are likely to form and the emulsification ability is reduced. I can't help it. The amount of the emulsifier to be used is 0.5 to 10 parts by weight, preferably 1 to 5 parts by weight, per 100 parts by weight of the low-molecular weight polylene rubber.

If the amount is too large, there is no particular problem with stability, but if it is used in excess, it acts as a laxative and at the same time is undesirable in terms of physical properties. Although it is possible to form an emulsion with less than 0.5 parts by weight, the particle size becomes large and creaming and separation phenomena are observed, which is not preferable.

The water-dropping polymer having a functional group based on maleic anhydride used in combination with the emulsifier in the present invention is:
A maleic anhydride copolymer consisting of one or more monomers selected from the group consisting of Q-olefins and vinyl compounds and maleic anhydride is reacted with a basic compound to make it water-soluble and produce a reaction product. means.

In addition, one or more monomers selected from the group consisting of Q-olefins and vinyl compounds, and one or more maleic acid derivatives selected from the group consisting of maleic acid, maleic acid ester, maleic acid amide, and maleic acid imide. It also means a hydric maleisic acid derivative copolymer consisting of.
The maleic anhydride-based copolymer or maleic acid derivative-based copolymer is obtained by radical polymerization of a Q-olefino or vinyl compound and a maleic anhydride or a maleic acid promoter in a solvent. Here, Q-olefin means a linear or branched unsaturated hydrocarbon having 2 to 12 carbon atoms, preferably 2 to 8 carbon atoms, and examples include ethylene, propylene, butene-1, butene-2, Isobutylene, n-pentene, isoprene, 2-methyl-1-butene, n-hexene, 2-methyl-1-bentene, 3-methyl-1-pentene, 4-methyl-1-bentene, 2-
Ethyl-1-butene, diisobutylene, 1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene,
1,3-octadiene, 2-methyl-4-dimethyl-1
-pentene, 2-methyl-4-dimethyl-2-besotene. Here, isobutylene also means return BB containing isobutylene. In addition, vinyl compounds refer to unsaturated compounds that can be copolymerized with maleic anhydride, etc.
For example, styrene, vinyl chloride, vinyl acetate, vinyl propionate, acrylonitrile, methyl vinyl ether,
These include acrylic acid esters or vinyl alcohol obtained by saponifying vinyl acetate.

These monomers may be used alone or in combination of two or more.

Among these monomers, Q-olefins, olefins such as ethylene and isobutylene, and methyl vinyl ether are preferably used, but the use of Q-olefins, especially isobutylene, is most consistent with the intended purpose of the present invention. . The composition ratio of the Q-olefinic or vinyl compound and maleic anhydride in the maleic anhydride copolymer is such that the reaction product obtained by reacting the formed maleic anhydride copolymer with a basic compound is Any amount may be used as long as it is soluble in water.

In the case of each copolymer of ethylene, isobutylene or methyl vinyl ether and maleic anhydride preferably used in the present invention, 0% of ethylene, isobutylene or methyl vinyl ether is used per 1 mol of maleic anhydride.
．． The amount is about 5 to 3 moles, and in most cases about 1 mole. In addition, the molecular weight of this maleic anhydride copolymer is such that the polar viscosity measured at 30 oo in dimethylformamide solution is 0.0.
5 to 5, preferably about 0.1 to 3.

Examples of the basic compound used for dehydrating the maleic anhydride copolymer include caustic alkalis such as sodium hydroxide and potassium hydroxide, alkali carbonates, ammonia, and lower amines.

In particular, when a maleic anhydride copolymer is made water-soluble using ammonia, an aqueous emulsion that best meets the intended purpose of the present invention can be provided.
The reaction between the maleic anhydride copolymer and the basic compound can be carried out by adding the maleic anhydride copolymer to an aqueous solution of the basic compound and reacting it under heating or at room temperature. This is done by melt-contacting a maleic anhydride copolymer with a gas.
The reaction ratio between the maleic anhydride-based copolymer and the basic compound may be any amount as long as the amount is sufficient to make the maleic anhydride solubilized in water, but in many cases, the reaction ratio of the maleic anhydride-based copolymer and the basic compound may be any amount. The amount of the basic compound is 0.5 to 2 mol, preferably 1 to 2 mol, per 1 mol of maleic anhydride group. The water-soluble monopolymer having a functional group based on maleic anhydride produced in this way does not reduce any of the effects brought about by the polyoxyethylene alkyl (allyl) ether phosphate used as an emulsifier in the present invention. It is very effective in providing a low molecular weight polygene rubber aqueous emulsion for rubber latex modification that can prevent the formation of crater-like avatars on the film surface of thin latex products without the need for other water-soluble polymers. It is a unique thing not seen in other countries.

The amount of the water-soluble polymer based on maleic anhydride used is 0.1 to 5 parts by weight per 100 parts by weight of the low molecular weight polylene rubber.
Parts by weight, preferably 0.2 to 3 parts by weight. If it is too large, it is uneconomical and at the same time the viscosity of the obtained aqueous low molecular weight polylene rubber emulsion becomes high, making it difficult to handle. On the other hand, if it is too small, it does not have the effect of preventing the formation of crater-like avatars, which is the desired objective of the present invention. Low molecular weight polyene rubber aqueous emulsion cannot be obtained. Note that this water-soluble polymer can be used either as a powder or as an aqueous solution without any problem in forming an emulsion.
Typical examples of the procedure for emulsifying low molecular weight polylene rubber are as follows. {1' A water-soluble polymer having a functional group based on low molecular weight polyene rubber, emulsifier, polyoxyethylene alkyl (allyl) ether phosphate (hereinafter simply referred to as "emulsifier") and maleic anhydride (hereinafter simply referred to as "water-soluble") A predetermined amount of a polymer (hereinafter abbreviated as "polymer") is mixed, and then water is gradually added under pressure.

■ Mix a predetermined amount of "emulsifier" and "water-soluble polymer" with low molecular weight polygene rubber, and add this to the aqueous phase under Kenazusa.

Lake The emulsifier and water-soluble polymer are dissolved in the water phase and added to the low molecular weight polygene rubber using a pestle.

[4) The "emulsifier" and "water-soluble polymer" are dissolved in the aqueous phase, and low-molecular-weight polygene rubber is added to this under the loss of water.

In addition, there is a method of simultaneously adding an aqueous phase or an oil phase containing an "emulsifier" or "water-soluble polymer," or a method of adding an "emulsifier" and "
There are methods such as including a "water-soluble polymer" in separate phases and mixing these two phases, but among these methods, one method that can obtain an emulsion with a particle size of 4 mm and good stability. The procedure shown in {1) is most preferred.

Note that these procedures may be carried out in combination, but whichever method is used, at least the final stage of mixing water and low molecular weight polyene rubber is performed using a homogenizer, colloid mill, homomixer, or guife. It is preferable to emulsify to a smaller particle size using an emulsifying machine such as a line mixer or a Di-Isper Mill ultrasonic emulsifying machine. In order to obtain an emulsion with finer particle size, an appropriate temperature (
It is more preferable to carry out the above operation while flooding at a temperature of, for example, 50 to 100°C. Furthermore, the amount of water used during emulsification also has a large effect on the emulsion itself and the stability of the emulsion produced. Good results can be obtained by using 10 to 100 parts by weight, more preferably 10 to 40 parts by weight, per 100 parts by weight of low molecular weight polyene rubber. If the amount of water is too large, that is, 100 parts by weight or more, it is not preferable because it impairs not only productivity and economic efficiency but also the stability of the emulsion. If the amount is less than 10 parts by weight, the viscosity of the emulsion becomes too high, making it difficult to form an emulsion. When forming an emulsion, good results can be obtained by adding an antifoaming agent as necessary. In other words, if there is a lot of foaming during emulsification, the foam will cause cavitation (idling) in the rotor blades and rotating slits of the emulsifying machine, or a reduction in performance (in general, excessive cavitation will significantly reduce emulsification efficiency). Therefore, it is thought that adding an antifoaming agent will be effective. Further, oil, tackifier resin, wax, etc. may be mixed with the low molecular weight polylene rubber to form an emulsion, or furthermore, a small amount of a solvent may be added to form an emulsion.

The low-molecular-weight polygene rubber obtained in this way does not cause problems with foaming or coagulation during its production, but it has a particle size of 0.1 to 15 mm, more precisely 0 in many cases. It has a uniform particle diameter within the range of .5 to 10 F, and has excellent storage stability as well as mechanical stability.

In addition, this low molecular weight polyene rubber aqueous emulsion is
It has excellent miscibility with solid rubber latex, exhibits excellent rubber physical properties that are not exhibited by aqueous emulsions of low-molecular-weight polyene rubbers with molecular weights of several thousand, and is also excellent in co-vulcanization. In addition, when it is blended with rubber latex such as natural rubber latex and a vulcanized sheet is produced from it, a uniform film surface with no crater-like avatars is provided. Low molecular weight polygene rubber water-based emulsion having these characteristics is used by blending with solid rubber latex, and is used to impart tackiness to unvulcanized latex adhesives, foam rubber, balloons, gloves, medical hygiene products, etc. In addition to softening various latex products, it is particularly effective in improving the flexibility of balloons, surgical gloves, sanitary products, and other products that require a strictly uniform, even surface.

Note that this aqueous emulsion may be used alone or for other purposes without any problem. The solid rubber latex used by blending with this low molecular weight polygeso rubber aqueous emulsion includes natural rubber latex, synthetic cis-1,4-polyisoprene rubber latex, polybutadiene rubber latex, styrene-butadiene copolymer latex, Examples include styrene-isoprene rubber copolymer latex and butadiene-acrylonitrile copolymer latex.

Among them, from various points of view including compatibility and co-vulcanization, low molecular weight isoprene rubber aqueous emulsion such as low molecular weight polyisoprene rubber or low molecular weight poly(inprene-butadiene) rubber, natural rubber latex or Best results are obtained when combined with synthetic cis-1,4-polyisobrene rubber latex. In some cases, it may be used in a blend with a synthetic resin emulsion such as a vinyl acetate emulsion or an acrylic emulsion. Also, if necessary,
It is used in combination with vulcanization accelerators, anti-aging agents, other compounded chemicals or fillers. EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples in any way. Example 1 A low molecular weight polyisoprene rubber having a molecular weight of 25,000 was obtained by polymerizing isoprene monomer using a butyl lithium catalyst.

10 parts by weight of this low molecular weight polyisoprene rubber was placed in a container, and 3 parts by weight of an emulsifier and 1 part by weight of a water-soluble polymer having a functional group based on maleic anhydride were added to form a homogeneous mixture. . As the emulsifier, polyoxyethylene alkyl (allyl) ether phosphate (OAFAC RE-610 manufactured by Toho Chemical Industry Co., Ltd.) with an added mole number of ethylene oxide of 12 is used, and the water-soluble emulsifier has a functional group based on maleic anhydride. As the polymer, a reaction product obtained by reacting isobutylene-maleic anhydride (alternating) copolymer with ammonia and having an intrinsic viscosity of 0.4 (d'/unit) measured at 3000 °C in a dimethyl formaldehyde solution is used. (Claray Soprene Chemical ■
Isoban 104) was used. 8000 ml of the mixture
While holding a light ceremony using a propeller-type high-speed fly punch machine in a constant temperature bath, 8
While gradually adding 7 parts by weight of preheated warm water to 000,
An emulsion with a solid content concentration of 59% was prepared. This emulsion was extremely stable, with no separation observed even after being left for one week. The emulsion thus obtained was blended with natural rubber latex containing rubber compounding chemicals, and after being molded into a vulcanized sheet by a conventional method, the surface of the obtained vulcanized sheet was observed using a 40x magnifying glass. The specific results are shown in Table 2, and it was found that the surface of the vulcanized sheet was uniform with almost no crater-like avatars observed. Note that the vulcanized sheet was prepared by the following method. That is,
First, natural rubber latex, emulsion, and rubber compounding chemicals were mixed in the proportions shown in Table 1. No problems such as foaming or coagulation occurred during mixing. Water was added to the obtained natural rubber latex composition to adjust the concentration to 45%, and the mixture was aged at 5,000 yen. Next, a glass plate coated with a coagulant for dipping (30% methanol solution of calcium nitrate) was dipped in the aged natural rubber latex composition for a certain period of time to form a film, and the resulting film was heated at 5000°C for 15 minutes. Dry for a minute. Next, the film was treated in 50 qo warm water for 30 minutes to wash away the coagulated liquid adhering to the film. 7 more
After drying at 0°C for 2 hours, it was vulcanized at 10,000°C for 40 minutes. After the obtained vulcanized sheet was left indoors, its surface was observed using a No. 4 magnifying glass. Table 1 * Weight comparison example based on solid content 1 Isoptylene-maleic anhydride copolymer, which is a water-curable polymer having a functional group based on polyoxyethylene alkyl (allyl) ether phosphate, which is an emulsifier, and maleic anhydride. Instead of using the emulsifiers shown in Table 2 (potassium rosinate, potassium oleate, morpholine oleate, triethanolamine oleate, polyoxyethylene alkyl(ally) ether phosphate, and isobutylene), A low molecular weight polyisoprene rubber aqueous emulsion was prepared in the same manner as in Example 1, except that a maleic anhydride copolymer and an ammonia reaction product were used.

When the isoptylene-maleic anhydride copolymer ammonia reaction product (Y) was used, it was not possible to form an emulsion, but when other emulsifiers 'a) to {f} were used, stable emulsions were formed. was gotten. Each of the emulsions thus obtained was mixed with natural rubber latex in the same manner as in Example 1 to obtain a natural rubber lax composition, and a vulcanized sheet was prepared from the composition.

When these vulcanized sheets were subjected to film surface evaluation, the results shown in Table 2 were obtained. As can be seen from Table 2, when a vulcanized sheet was prepared using the low molecular weight polyisoprene rubber aqueous emulsion prepared using the emulsifier {a' to 0 of Comparative Example 1 as a modifier for natural rubber latex, A large number of crater-like avatars were observed on the film surface. This was the same when only the polyoxyethylene alkyl (allyl) ether phosphate used as the emulsifier in Example 1 was used (see [f-- in Comparative Example 1). Comparative Example 2 A low molecular weight polyisoprene rubber aqueous emulsion prepared using only polyoxyethylene alkyl (allyl) ether phosphate as an emulsifier (i.e. emulsion 'f} of Comparative Example 1). The same amount of the isobutylene-maleic anhydride copolymer ammonia-reactive product as in Example 1 was added to prepare a low molecular weight polyisoprene rubber aqueous emulsion having apparently the same composition as in Example 1.

This emulsion was blended with natural rubber latex to prepare a vulcanized sheet in the same manner as in Example 1. When this vulcanized sheet was subjected to film surface evaluation in the same manner as in Example 1, the results shown in Table 2 were obtained. As can be seen, the ammonia reaction product of isobutylene-maleic anhydride copolymer is added later to form a two-mulsion, which looks the same as in Example 1, and is used as a modifier for natural rubber latex. It can be seen that the number of crater-like avatars generated on the film surface remains essentially the same, indicating that there is no improvement. Table 2 1 The vulcanized sheet was observed with a 4-tone magnifying glass, and evaluated based on the number of crater-shaped abacuses present on the LC film surface (average of 10 locations).

○: The average number of crater-shaped avatars is 1 or less.

x: 〃 〃 5 that's all.

2 Polyoxyethylene alkyl (allyl) ether phosphate 3 Ammonia reaction product of isobutylene-hydro-maleic acid copolymer 4 Addition of Isoban 104 to the low molecular weight polyisoprene rubber aqueous emulsion obtained by f of Comparative Example 1 A case where a low molecular weight polyisoprene rubber aqueous emulsion having the apparently same composition as in Example 1 was used.

5 Cannot be emulsified and cannot be evaluated.

Example 2 Molecular weight is 470 using butyl lithium catalyst
00 low molecular weight polysoph. A lotus rubber was prepared.
This low molecular weight polyisoprene rubber was emulsified in the same manner as in Example 1 to obtain a low molecular weight polyisoprene rubber aqueous emulsion. However, polyoxyethylene alkyl ether phosphate (GAFAC RS-610 manufactured by Toho Chemical Industry Co., Ltd.) is used as an emulsifier, and a water-soluble polymer having a functional group based on maleic anhydride is used in a dimethylformamide solution. A reaction product obtained by reacting ammonia with isobutylene-maleic anhydride (alternating) polymer having an intrinsic viscosity of 1.0 (d'/polymer) measured at 1
10) was used. Emulsion formation was extremely easy, and the resulting emulsion was also extremely stable. Using this emulsion as a modified natural rubber emulsion, a vulcanized sheet was prepared from natural rubber latex in the same manner as in Example 1, and the film surface was evaluated. As a result, almost no crater-like avatar was observed on the film surface. Met.

In addition, when an emulsion prepared only with the above-mentioned emulsifier was used, many crater-like abrasions were observed on the film surface of the vulcanized sheet. Also, isobutylene
When only the maleic anhydride copolymer ammonia reaction product was used, it was not possible to form an emulsion.
This shows that the film surface of the vulcanized sheet is improved by using the emulsifier and the water-soluble polymer together. Example 3 By polymerizing isobrene monomer and butadiene monomer using a butyllithium catalyst, the molecular weight was 3700.
0, the composition weight ratio of isoprene/butadiene is 70/3
A low molecular weight poly(in-prene-butadiene) rubber having a molecular weight of 0 was prepared.

This low molecular weight rubber was mixed with the emulsifier used in Example 1 and the water-soluble polymer having a functional group based on maleic anhydride as a third compound.
Emulsions were made using the proportions shown in the table. The emulsion thus obtained was mixed as an emulsion for modifying natural rubber in the same manner as in Example 1, and then a vulcanized sheet was prepared. When the film surface was evaluated in the same manner as in Example 1, the results shown in Table 3 were obtained. Table 3 1 Polyoxyethylene alkyl (allyl) ether phosphate 2 Reaction product obtained by reacting isobutylene-maleic anhydride copolymer with ammonia.

3 Same as Example 1 Example 4 and Comparative Example 3 The molecular weight obtained using a butyllithium catalyst was 4500
A low molecular weight polyisoprene rubber aqueous emulsion was prepared in the same manner as in Example 1 except that the low molecular weight polyisoprene rubber of 0 was used.

This emulsion had excellent stability. For comparison, the low molecular weight polyisoprene was emulsified using 4 parts by weight of potassium rosinate to prepare a somewhat stable emulsion. Natural rubber latex compositions were prepared in the same manner as in Table 2, except that the amounts of these two types of emulsions and natural rubber latex were varied, and then vulcanized sheets were made from them.

When the film surface of the vulcanized sheet was evaluated, the results shown in Table 4 were obtained, and the emulsion obtained in the present invention imparts flexibility to the vulcanized sheet obtained from the natural rubber latex composition. It can also be seen that the film surface is uniform with almost no crater-like abrasions. Fourth
Tables 1), 2), 3) Same as Example 1

Claims (1)

[Claims] 1. Emulsion of a low molecular weight polydiene rubber having a molecular weight of 10,000 to 60,000 in the presence of a water-soluble polymer having functional groups based on polyoxyethylene alkyl (allyl) ether phosphate and maleic anhydride. A method for producing a low molecular weight polydiene rubber aqueous emulsion, characterized by the following. 2. The manufacturing method according to claim 1, wherein the low molecular weight polydiene rubber is polyisoprene rubber or poly(isoprene-butadiene) rubber having a vinyl bond content of 35% or less. 3. The manufacturing method according to claim 1 or 2, wherein the water-soluble polymer having a functional group based on maleic anhydride is a reaction product of an isobutylene-maleic anhydride copolymer and ammonia.