JP2631212B2 - Thermosensitive gelling agent for latex - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a novel heat-sensitive gelling agent for latex,
More specifically, the present invention relates to a novel heat-sensitive gelling agent for a latex, which can efficiently gel a latex by adding a small amount to the latex.

2. Description of the Related Art As heat-sensitive gelling agents for latex, inorganic metal salts, polyvinyl methyl ether, polypropylene glycol, alkylene oxide adducts of alcohols and alkyl phenols, and the like have hitherto been known. However, such a conventional thermosensitive gelling agent, when added to a latex, destabilizes the latex and deteriorates storage stability, and when the latex is heat-coagulated, the latex may not completely coagulate. . Furthermore, the conventional heat-sensitive gelling agent requires a large amount to be added to the latex, which reduces the initial action and effect of other components in the latex, and also reduces the product obtained by heat coagulation of the latex. It may have a detrimental effect on physical properties.

On the other hand, in recent years, a polysiloxane-based alkylene oxide adduct has been proposed as a heat-sensitive gelling agent for latex. According to this, although the above-mentioned drawbacks have been improved to some extent, they are significantly more expensive than the above-mentioned conventional heat-sensitive gelling agents, and therefore increase the production cost of a heat-sensitive latex using the same. It will be.

Problems to be Solved by the Invention The present inventors have conducted intensive studies to solve the above-mentioned problems in the conventional heat-sensitive gelling agent for latex, and as a result, have found that alkylphenol-formalin condensate ethylene oxide and propylene oxide The present inventors have found that a co-adduct of the invention can efficiently form a latex into a thermosensitive gel by adding a small amount to the latex, thereby leading to the present invention.

Accordingly, an object of the present invention is to provide a novel heat-sensitive gelling agent for latex, which can efficiently gelate a latex by adding a small amount thereof.

Means for Solving the Problems The heat-sensitive gelling agent for latex according to the present invention has an alkyl group having 1 to 30 carbon atoms and an average degree of condensation of 2 to 20.
In the thermosensitive gelling agent for latex comprising a co-adduct of ethylene oxide and propylene oxide of an alkylphenol-holimarin condensate, the addition mole number of ethylene oxide and propylene oxide is the above-mentioned alkylphenol-
The total amount of the coadduct is in the range of 30 to 600 mol per mol of formalin condensate, and the cloud point is in the range of 0 to 100 ° C.

The alkylphenol-formalin condensate is a known compound, and can be obtained, for example, by condensing an alkylphenol and formalin by heating in a solvent in the presence of an acid or alkali catalyst. it can. In the present invention, the number of carbon atoms of the alkyl group of the alkylphenol in the alkylphenol-formalin condensate is in the range of 1 to 30, and the average degree of condensation is in the range of 2 to 20. Here, the degree of condensation refers to the number of alkylphenols in the condensate.

The alkylphenol used in the production of the alkylphenol-formalin condensate has at least one alkylphenol on the aromatic ring.
It refers to a compound having two hydroxyl groups and at least one alkyl group, but usually a monoalkylphenol is used. In such a monoalkylphenol, the substitution position of the alkyl group may be any, but is preferably para to the hydroxyl group. Particularly, the alkylphenol preferably used in the present invention is a p-alkylphenol having an alkyl group having 4 to 9 carbon atoms.

The alkylphenol-formalin condensate ethylene oxide and propylene oxide coadduct is a compound obtained by adding both ethylene oxide and propylene oxide to the alkylphenol-formalin condensate as described above. According to a conventional method, alkylphenol-
The formalin condensate can be obtained by reacting ethylene oxide and propylene oxide under heating in the presence of an alkali catalyst.

In the co-addition of ethylene oxide and propylene oxide to the alkylphenol-formalin condensate, either one may be added first or simultaneously, and the addition form may be block or random. The added block is preferred.

Further, in the present invention, the total addition mole number of ethylene oxide and propylene oxide in the ethylene oxide and propylene oxide co-adduct of the alkylphenol-formalin condensate having the average degree of condensation as described above is the above alkylphenol-formalin 30 to 60 per mole of condensate
It is in the range of 0 mol, particularly preferably in the range of 90 to 450 mol. When the number of moles is less than 30 moles, the adduct has poor thermal gelling effect, while when it exceeds 600 moles, when the adduct is added to the latex, the latex thickens strongly even at room temperature. This is not preferred. The cloud point of the adduct is in the range of 0 to 100 ° C, and particularly preferably in the range of 20 to 70 ° C. When the cloud point of the adduct is lower than 0 ° C, handling is not easy,
When the temperature exceeds, it is difficult to obtain a thermosensitive gelling effect.

When used, the heat-sensitive gelling agent for latex according to the present invention varies depending on the type of latex used, but is generally 0.01 to 10 parts by weight per 100 parts by weight of latex.
It is added in the range of parts by weight. In particular, a preferable addition amount is
It is in the range of 0.1 to 3 parts by weight based on 100 parts by weight of latex. When the added amount is less than 0.01 part by weight per 100 parts by weight of latex, the heat-sensitive gelling effect is poor, while
Exceeding 10 parts by weight is not preferred because it may have a harmful effect on the latex and its products.

The heat-sensitive gelling agent for latex according to the present invention is, in addition to the alkylphenol-formalin condensate alkylene oxide adduct described above, in order to improve its performance,
If necessary, a surfactant, an inorganic salt, a dispersant, and the like can be further contained as long as the gelling effect of the heat-sensitive gelling agent, the latex, and the quality performance of the product are not impaired.

The thermosensitive gelling agent according to the present invention can be used for any latex, and is not particularly limited. Therefore, for example, in addition to natural rubber latex, styrene, butadiene, isoprene, acrylonitrile, ethylene,
It can be used for various synthetic copolymer latexes obtained by using monomers such as ethylenically unsaturated carboxylic acids such as methacrylates such as vinyl acetate and methyl methacrylate, and acrylates such as butyl acrylate. .
Specific examples of such latex include, for example, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, methyl methacrylate-butadiene copolymer, methyl methacrylate-styrene-butadiene copolymer latex as a main component. Can be mentioned. Also, various modified latexes, for example, carboxyl-modified latex and the like are preferably used.

These latexes may contain, for example, various fillers such as calcium carbonate and aluminum hydroxide, thickeners such as carboxymethylcellulose, and other antioxidants and defoamers, depending on the intended use. .

The thermosensitive gelling agent according to the present invention may be added to a latex to be thermosensitively gelled at the time of its use, or added during the production of the latex, but the former method is usually preferred. Further, the heat-sensitive gelling agent according to the present invention is, for example, a heat-sensitive gelling agent in a latex or the like used for a dipped rubber product, a foam rubber, a nonwoven fabric binder, or the like, and further, in the production of an ABS resin or the like, a resin is extracted from the latex. It is suitably used as a coagulant or the like at the time of separation.

Effects of the Invention The heat-sensitive gelling agent for latex according to the present invention can efficiently gelate the latex by adding a small amount to the latex, so that the inherent performance of the latex is not impaired.

EXAMPLES Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to these examples. still,
In the following, parts and% mean parts by weight and% by weight, respectively.

Example 1 In a test tube, 100 parts of a carboxyl-modified styrene-butadiene-based synthetic rubber latex (Croslen SA-65 manufactured by Takeda Pharmaceutical Co., Ltd.) and 5 parts of a 10% aqueous solution of a thermosensitive gelling agent shown in Table 1 were mixed. Thereafter, the mixture was heated in a water bath at 90 ° C., and the change in viscosity was measured with a B-type viscometer (rotor No. 3, rotating speed: 12 rpm). The point at which the viscosity exceeded about 10,000 centipoise was defined as the freezing point. The results are shown in Table 1.

In Table 1, n is the average degree of condensation of the alkylphenol-formalin condensate used, and EO and PO are the averages per molecule of a co-adduct of ethylene oxide and propylene oxide of the alkylphenol-formalin condensate. Shows the number of moles added. In the table, the evaluation criteria are as follows.

◎ Coagulates within 4 minutes.

By comparing the invention examples with Comparative Examples 1 to 3, the alkylene oxide-formalin condensate alkylene oxide adduct is superior to the alkylphenol oxide alkylene oxide adduct in the thermal gelation effect, and the invention examples By comparison with Comparative Examples 4 and 5, the alkylene oxide adduct of the alkylphenol-formalin condensate has excellent thermal gelation performance of latex when the number of moles of ethylene oxide and propylene oxide added is large. Is shown. However, as shown in Comparative Example 8, when the added mole number of ethylene oxide and propylene oxide is too large, the latex is strongly thickened even at room temperature.

On the other hand, by comparing the invention examples with Comparative Examples 6 and 7, it is shown that the alkylphenol-formalin condensate alkylene oxide adduct has poor heat-sensitive gelling performance when the cloud point exceeds 100 ° C. .

Example 2 In Example 1, an acrylic emulsion (Polysol AT-113 manufactured by Showa Polymer Co., Ltd.) was used as a latex.
The thermosensitive gelling performance was evaluated in the same manner as in Example 1 except that the compound was used. The results are shown in Table 2.

It is clear that the heat-sensitive gelling agent of the present invention is superior in the heat gelling effect even in the case of an alkyl latex, as compared with the alkylene oxide adduct of alkylphenol or bisphenol A.

Claims (1)

(57) [Claims] 1. A latex comprising a co-adduct of ethylene oxide and propylene oxide of an alkylphenol-formalin condensate having an alkyl group having 1 to 30 carbon atoms and an average degree of condensation of 2 to 20. In the heat-sensitive gelling agent, the addition mole number of ethylene oxide and propylene oxide is in the range of 30 to 600 mol in total per 1 mol of the alkylphenol-formalin condensate, and the cloud point is 0 to 100 ° C.
A heat-sensitive gelling agent for latex, comprising the above-mentioned co-adduct in the range of.