Chloroprene polymer latex composition

Abstract

To provide a chloroprene polymer latex composition that is suitable for dip molding by a direct method and enables formation of a film with excellent surface smoothness.SOLUTION: A chloroprene polymer latex composition comprises a viscosity modifier and has a viscosity in the range of 15 to 200 mPa s.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a chloroprene polymer latex composition. [Background technology]

[0002] Chloroprene polymer latex has a good balance of mechanical strength, weather resistance, oil resistance, heat resistance, flame retardancy, adhesiveness, etc., and is therefore widely used in applications such as dip-molded products such as gloves and films, rubber threads, adhesives, and surface treatment agents. In particular, for dip-molded product applications, there are three main methods for obtaining dip-molded products, which are called the direct method, adhesion method, and thermal method. Among these, the adhesion method is often used for gloves, in which a coagulating liquid is applied to a former, which is then dried, and the product is obtained by dipping the former in a latex compound liquid (see, for example, Patent Document 1).

[0003] On the other hand, the direct method, in which a product is obtained by directly immersing a former in a latex compound liquid, is mainly applied to products that require a thin film (condoms, balloons, finger cots, etc.). Although there are many patent documents for dip molding using the direct method for natural rubber latex, isoprene latex, and water-based polyurethane latex (see, for example, Patent Documents 2 and 3), there are no patent documents for compositions dip molded using the direct method with chloroprene polymer latex, and furthermore, no technology has been established for obtaining a film with a good surface condition in which flow marks (dripping), which are a frequent problem during dip molding, have been improved. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2011-122141 A [Patent Document 2] Special Publication No. 2010-512898 [Patent Document 3] JP 2010-215903 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in view of the above problems, and an object of the present invention is to provide a chloroprene polymer latex composition which can provide a coated product by dip molding using a direct method, and which can provide a coated product having excellent surface smoothness. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to solve the above problems and have completed the present invention. That is, the present invention has the following aspects [1] to [5]. [1] A chloroprene polymer latex composition comprising a viscosity modifier and having a viscosity range of 15 to 200 mPas. [2] The chloroprene polymer latex composition according to [1], which contains zinc oxide and a vulcanization accelerator. [3] The chloroprene polymer latex composition according to [1] or [2], having a pH of 10.0 or more. [4] The chloroprene polymer latex composition according to any one of [1] to [3], which is applicable to dip molding by a direct method. [5] A method for producing a coated product, which comprises dip molding using the chloroprene polymer latex according to any one of [1] to [4] by a direct method. Effect of the Invention

[0007] The chloroprene polymer latex composition of the present invention is applicable to dip molding by a direct method, and can provide a coating having excellent surface smoothness by dip molding. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The present invention will be described in detail below.

[0009] The chloroprene polymer latex composition of the present invention has a viscosity range of 15 to 200 mPas.

[0010] Various chloroprene polymer latex products are commercially available, including latexes containing homopolymers of chloroprene monomers, and latexes of copolymers of chloroprene monomers and monomers copolymerizable therewith. Examples of copolymerizable monomers include 2,3-dichloro-1,3-butadiene, 2-cyano-1,3-butadiene, 1-chloro-1,3-butadiene, 1,3-butadiene, styrene, acrylonitrile, methyl methacrylate, methacrylic acid, acrylic acid, and the like, and these can be used alone or in combination of two or more. The amount of these monomers is not particularly limited, but is preferably 0 to 20% by weight, so long as it does not impair the properties of the film obtained by dip molding.

[0011] The chloroprene polymer latex composition of the present invention must have a viscosity range of 15 to 200 mPas in order to obtain a coating having excellent smoothness by dip molding using a direct method.

[0012] In order to adjust the viscosity, a viscosity adjusting agent, an emulsifier, a pH adjusting agent, an acid acceptor, a filler, a reinforcing agent, an antioxidant, a plasticizer, a lubricant, zinc oxide, a vulcanization accelerator, sulfur, etc., or a dispersion obtained by dispersing these in water is added to the chloroprene polymer latex.

[0013] Among these, it is essential to include a viscosity modifier, and the type is not particularly limited, but an associative viscosity modifier is preferred, and the number of parts added is preferably 0.1 to 2.0 parts by weight, more preferably 0.1 to 1.2 parts by weight, per 100 parts by weight of the solid content of the chloroprene latex so as not to impair the physical properties of the film.

[0014] In order to obtain a coating film, it is preferable to contain zinc oxide, a vulcanization accelerator, or a dispersion liquid of these in water. The vulcanization accelerator is not particularly limited, but a coating film with a good surface condition can be obtained by containing at least one compound selected from the group consisting of thiuram vulcanization accelerators, guanidine vulcanization accelerators, thiourea vulcanization accelerators, carbamate vulcanization accelerators, thiazole vulcanization accelerators, and sulfenamide vulcanization accelerators, preferably in an amount of 0.1 to 5 parts by weight, more preferably 0.5 to 3 parts by weight, based on 100 parts by weight of the solid content of the chloroprene latex.

[0015] Since the chloroprene polymer latex composition deacidifies over time and the pH value decreases, the pH value is preferably 10.0 or more, more preferably 12.0 or more, in order to improve storage stability. When adjusting the pH value, the pH value can be adjusted to the above range by adding sodium hydroxide or potassium hydroxide.

[0016] To manufacture a film product by dip molding using the chloroprene polymer latex composition of the present invention, a direct dip molding technique can be used. For example, a film is obtained by immersing a mold of a target vulcanized rubber molding in the chloroprene polymer latex composition of the present invention and drying it. A multi-layer CR film is obtained by repeating immersion and drying until a desired thickness is obtained. Further, the rubber film and the mold are immersed in water, and excess emulsifier and the like are washed away, and then the film and the mold are heated in an oven or the like to perform drying and vulcanization. EXAMPLES

[0017] The present invention will be described in more detail with reference to the following examples, although the present invention is not limited thereto.

[0018] The values ​​used in these examples were obtained in accordance with the following measurement methods.

[0019] <Viscosity measurement> The viscosity (mPas) of the chloroprene polymer latex composition was measured at 23°C using a B-type viscometer (manufactured by Eiko Seiki Co., Ltd.). When the viscosity was 100 mPas or less, it was measured using an LV-1 spindle at a rotational speed of 60 rpm. When the viscosity was 100 or more, it was measured using an LV-2 spindle at a rotational speed of 60 rpm.

[0020] <pH measurement> It was measured using a glass electrode type hydrogen ion concentration indicator (manufactured by Horiba, Ltd.).

[0021] <Film state> 〇: There are no flow marks (drips) or cracks on the film surface, and it is smooth.

[0022] ×: There are flow marks (drips) and cracks on the film surface.

[0023] Example 1 First, zinc oxide, sulfur, vulcanization accelerator DPTU (N,N'-diphenylthiourea), and vulcanization accelerator DPG (1,3-diphenylguanidine) were adjusted to a state of aqueous dispersion. For each 100 parts by weight, 3 parts by weight of ammonium casein, 3 parts by weight of a formalin condensate of sodium naphthalenesulfonate, and 100 parts by weight of distilled water were mixed respectively, and stirred in a ball mill for 1 day to prepare a stable dispersion of each compounding agent.

[0024] Taking the solid content of the chloroprene polymer latex (chloroprene polymer manufactured by Tosoh Corporation, trade name: Skyprene LA-502) as 100 parts by weight, 0.6 part by weight of an associative viscosity modifier (manufactured by Adeka Corporation, trade name: Adekanol UH-438), 5 parts by weight of zinc oxide, 2 parts by weight of vulcanization accelerator DPTU, 1 part by weight of vulcanization accelerator DPG, 4 parts by weight of an antioxidant (manufactured by Chuo Kasei Co., Ltd., trade name: Wingtay-L), and 1 part by weight of sulfur, the suspension of each compounding agent was added to the chloroprene polymer latex, and stirred for 18 hours to prepare a latex composition.

[0025] A borosilicate glass mold having an outer diameter of 38 mm was heated to 40°C, immersed in the prepared chloroprene polymer latex composition, and dried at 100°C to form a rubber film on the mold. This was repeated three times, and then the mold and the mold were immersed in warm water at 60°C to elute water-soluble impurities. After drying at 70°C for 10 minutes, the surface condition of the film was observed.

[0026] Examples 2 to 7 In the same manner as in Example 1, the target chloroprene latex polymer compositions were obtained with the compositions shown in Table 1. Then, in the same manner as in Example 1, the immersion operation was carried out and the film state was observed.

[0027] [Table 1]

[0028] Comparative Example 1 The target chloroprene polymer latex composition was obtained by adjusting the viscosity with the composition shown in Table 2 in the same manner as in Example 1. The coating surface had many cracks and was poor in coating smoothness.

[0029] Comparative Example 2 As in Example 1, dip molding was performed by the direct method using the composition shown in Table 2 without adding a viscosity modifier, and the film was observed. The film surface had many flow marks (dripping), and the film smoothness was poor.

[0030] Comparative Example 3 The target chloroprene polymer latex composition was obtained by adjusting the viscosity with the composition shown in Table 2 in the same manner as in Example 1. The coating surface had many flow marks (dripping liquid) and the coating smoothness was poor.

[0031] Comparative Example 4 The target chloroprene polymer latex composition was obtained by adjusting the viscosity with the composition shown in Table 2 in the same manner as in Example 1. The coating surface had many cracks and was poor in coating smoothness.

[0032] [Table 2] [Industrial Applicability]

[0033] The chloroprene polymer latex composition of the present invention can be easily dip-molded and used as a thin dip-vulcanized film, for example, for condoms, finger cots, balloons, and the like.

Claims

1. A chloroprene polymer latex composition comprising a viscosity modifier and having a viscosity range of 15 to 200 mPas.

2. 2. The chloroprene polymer latex composition of claim 1, comprising zinc oxide and a vulcanization accelerator.

3. 3. The chloroprene polymer latex composition according to claim 1, which has a pH of 10.0 or more.

4. 3. The chloroprene polymer latex composition according to claim 1, which is applicable to dip molding by a direct method.

5. A method for producing a coated product, comprising dip molding using the chloroprene polymer latex according to claim 1 or 2 by a direct method.

Images