JP3523757B2 - Method for preventing adhesion of natural rubber latex film - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to coating a rubber film with a mixed monomer consisting of a hydrophobic monomer and a water-soluble monomer and irradiating it with an electron beam to form a hydrogel film on the surface of the rubber film. Is related to the reduction of

[0002]

2. Description of the Related Art Natural rubber latex film is flexible and has high strength, so
It is used in thin products such as test gloves, contraceptives, and catheters. Since the surface of these rubber products is often rich in tackiness, a method of chlorinating the surface or applying a talc powder, and further an anti-sticking treatment by coating with hydrogel are performed. However, these anti-sticking treatments have some problems.

[0003]

In the chlorination process, since the product contains chlorine, hydrochloric acid is generated during incineration and pollutes the atmosphere. Further, in the talc treatment, since talc is a light powder, it may diffuse into the atmosphere together with the protein in the rubber during use, causing allergies even to those who do not handle rubber products directly. Also. Talc powder adheres to the hands of rubber gloves during use, and the hands become dirty. In the hydrogel coating method, a hydrogel polymer, which is a copolymer of 2-hydroxyethyl methacrylate and methacrylic acid and / or 2-ethylhexyl acrylate, and a curing agent are applied, and the hydrogel is bonded to a rubber film by a thermosetting reaction. A method is known (Patent Publication No. 5-13170). In this method, in order to increase the adhesiveness between the rubber film and the hydrogel film, after the surface treatment of the rubber film surface with an acid or alkali, the hydrogel is applied and the hydrogel coating is performed with the curing agent. There is a problem that the process is complicated and it takes time to remove the acid and the alkali. However, it is an important invention that finds that the coating of hydrogel is extremely effective in preventing sticking of the rubber film. In view of the above problems, it is an object of the present invention to provide a non-toxic and safe method for preventing sticking of rubber products.

[0004]

According to the present invention, a rubber film that has been subjected to a dipping process (that has been subjected to a dipping process in a hydrophobic monomer or a water-soluble monomer) is not subjected to complicated pretreatment, and a hydrogel of hydrogel is formed on the surface of the rubber film. It is characterized in that a monomer as a raw material is polymerized by the action of radiation and a rubber film is coated with a hydrogel. The monomer used is a mixed monomer of a hydrophobic monomer and a water-soluble monomer, which is uniformly applied on the surface of the rubber film and irradiated with a low energy electron beam to form a hydrogel film.

The inventor of the present invention has conducted extensive research on application of hydrogels to medical materials by means of radiation crosslinking. As a result, the adhesiveness of the surface of radiation-vulcanized natural rubber latex film is reduced by the formation of hydrogel film. I found that I could do it. The formation of the hydrogel film not only improves the adhesiveness, but in the case of rubber gloves, it absorbs sweat during use and improves the adhesion between the hands and the rubber gloves.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION There are the following two methods for producing a hydrogel film by radiation. A water-soluble polymer is dissolved in water and irradiated with radiation, and the dissolved polymer is crosslinked to form a hydrogel. The water-soluble monomer is irradiated with radiation to form a hydrogel by polymerization crosslinking.

As an example, there is a method of applying an aqueous solution of polyvinyl alcohol or polyvinylpyrrolidone, which is a water-soluble polymer, on the surface of a rubber film and irradiating it. As a result, a thin hydrogel film is formed on the surface of the rubber film, but there is a problem in that it lacks adhesiveness with rubber and is liable to cause delamination.

[0008] The method of 2 is acrylic acid or methacrylic acid 2
A method of coating and irradiating a water-soluble monomer such as hydroxyethyl, whereby a polymer film is formed. In this case, due to the action of radiation, a chemical bond is formed between the rubber and the polymer, and the problem of delamination hardly occurs. This polymer is highly water-soluble, and when it comes into contact with water, it absorbs water and becomes a hydrogel. In order to obtain a preferable hydrogel, the selection of the monomer is important, and if the selection is wrong, the polymer film becomes hard, and when a force is applied, the surface of the rubber film is cracked or the flexibility is hindered.

Therefore, in order to impart flexibility to the hydrogel film, a mixed liquid of a hydrophobic monomer and a water-soluble monomer adjusted so that the glass transition temperature of a polymer produced by irradiation is relatively close to that of a rubber film. The present invention has been achieved by finding that when a rubber film is dipped in and irradiated with, the adhesiveness of the rubber film can be reduced and the flexibility is not hindered.

The rubber product capable of improving the tackiness according to the present invention is made of natural rubber latex.
Such rubber products are, for example, surgical rubber gloves, inspection rubber gloves, household rubber gloves, radioactive contamination protection rubber gloves, catheters, condoms, balloons and the like. These rubber products are made by dipping a molding die in radiation-vulcanized natural rubber latex and drying the latex adhering to the die to form a product (dipping method), or by pouring the latex into the die and hardening it ( Manufactured by the coagulation method). A vulcanization operation is indispensable for the production of these products, but the present invention can be applied to a non-sulfur vulcanized latex such as sulfur vulcanization or radiation vulcanization regardless of the vulcanization method.

The monomers used in accordance with the present invention are: As a hydrophobic monomer,
The solubility in water at room temperature is 10 g / 100 g or less, and there are the following. Examples thereof include ethyl acrylate, n-propyl acrylate, n-butyl acrylate, i-butyl acrylate, 2-ethylhexyl acrylate, methylaminoethylminoethyl methacrylate and diethylaminoethyl methacrylate.

The water-soluble monomer has a solubility in water at room temperature of 10 g / 100 g or more, and includes the following. Acrylic acid, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methacrylic acid, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, meta N-vinylpyrrolidone, methoxyethylene glycol methacrylate, methoxypropylene methacrylate. Glycol, methoxy polyethylene glycol methacrylate, methoxy ethylene glycol acrylate, methoxy propylene glycol acrylate, methoxy polyethylene glycol acrylate,
Polyethylene glycol dimethacrylate and polyethylene glycol diacrylate. These are just representative examples. In addition to this, the glass transition temperature of the polymer is -4.
Monomers below 0 ° C can also be used.

These mixed monomers are effective for reducing the tackiness of the surface of natural rubber latex. In particular, since the hydrogel film formed by irradiation with the mixed monomer of 2-hydroxyethyl methacrylate and n-butyl methacrylate has a good affinity with the rubber film, it may be peeled off even if immersed in a 70 ° C water bath for 30 minutes. Absent. Moreover, the flexibility and strength of the rubber film are not deteriorated.

The composition ratio of the water-soluble monomer and the hydrophobic monomer and the irradiation dose are as follows. When the composition ratio of the water-soluble monomer is large, the composition itself is a hard polymer and thus does not adhere well to the surface of the soft rubber film and is cracked. Cause When the amount of the hydrophobic monomer is large, it is not a hydrogel film, so that when it is applied to a rubber glove, the adhesion to the skin is deteriorated. For this reason, the composition ratio is an important factor because it changes the texture of the rubber film surface in addition to the decrease in tackiness. The most preferable composition ratio that can improve the tackiness of the rubber film and maintain the texture before forming the hydrogel film is 50 to 80% by weight of the water-soluble monomer and 50 to 20% of the hydrophobic monomer.
%.

If the hydrogel film can be formed at a dose as low as possible, the surface treatment can be carried out in a short time, which is preferable because the productivity is improved. However, if the dose is too low, unreacted monomer that does not polymerize remains, so that leaching after irradiation is performed. In addition, it takes a long time to remove unreacted monomers. Therefore, it is preferable to select a dose at which the monomer is polymerized close to 100%.
This dose varies depending on the combination of the water-soluble monomer and the hydrophobic monomer and the composition ratio, but is from 30 kGy to 60 kG
y is preferred. 2-hydroxyethyl methacrylate 8 /
In the case of n-butyl acrylate 2, 60 kGy is the most preferable dose because it can reduce the tackiness most.

The irradiation temperature for producing the hydrogel film on the surface of the natural rubber latex film according to the present invention is 0.
C. to 50.degree. C. are preferred. Desirably 20 to 30
℃. Irradiation at 0 ° C. or lower reduces the reactivity of the mixed monomer, which is not preferable. On the other hand, when the temperature is 50 ° C or higher,
The composition changes as the monomer evaporates. In addition, the work area is contaminated by the volatilized monomer, which is not preferable.

The amount of mixed monomer in the natural rubber tex film applied according to the present invention should be adjusted so that the thickness of the polymer is 10 to 100 μm. The dipping time in the case of applying by the dipping method depends on the composition of the mixed monomer and the temperature and depends on the viscosity of the mixed monomer, but about several seconds is sufficient. When applying by a method such as spraying, a conventional spraying technique can be used. Irradiation is preferably performed immediately after coating the mixed monomer. In the case of the dipping method, the rubber film is applied to the mixed monomer by immersing the mold for molding in natural rubber latex and irradiating it when completely dried rubber products or when some water remains in the rubber film before drying. Perform and coat the hydrogel on one side of the rubber film. When the remaining one surface is coated with the hydrogel, the product produced by the dipping method may be turned upside down and mounted on a molding die, and the mixed monomer may be applied and irradiated again. The mixed monomer may be applied on either a dry rubber film or a rubber film in which water remains. In some cases, it may be preferable for some water to remain. Also in the case of the coagulation method, the hydrogel can be coated by applying the mixed monomer and irradiating it in the same manner as the dipping method.

The electron beam is preferably an electron beam from a low energy electron accelerator. The low-energy electron beam has a low penetrating power, so that it is easy to shield radiation and can be incorporated in a dipping line. The low-energy electron accelerator mentioned here is an electron accelerator having an acceleration voltage of 500 kV or less. A commercially available beam current of 5 to 300 mA can be used. In the irradiation incorporated in the dipping line, the rotating product is irradiated from the axial direction orthogonal to the rotation axis. In the case of the product of the coagulation method, irradiation is performed from directly above the products arranged on a conveyor or the like.

[0019]

The present invention will be described in more detail below with reference to Examples and Comparative Examples.

(Production of rubber film) 700 g of high ammonia natural rubber latex (60% rubber solid content in Malaysia) was collected in a glass flask equipped with a stirrer,
While stirring at a rate of 40 rpm, 150 ml of 1% aqueous ammonia and 9 ml of 10% potassium hydroxide aqueous solution were added. 5 parts by weight of n-butyl acrylate (manufactured by Toagosei Co., Ltd., polymerization inhibitor MEHQ 150
ppm) and stirred for 30 minutes. This was transferred to a 1-liter polyethylene container and irradiated with γ-rays from cobalt 60 at a dose rate of 10 kGy / hour for 2 hours at room temperature. γ
After the irradiation of the rays, the latex was cast on a glass plate, dried at room temperature until it became transparent, and then peeled off from the glass plate to a thickness of 0.
A 45 mm rubber film was obtained.

[0021]

Example 1 The rubber film prepared in the section (Preparation of rubber film) was dipped in a weight ratio of 2-hydroxyethyl methacrylate / 8 / n-butyl acrylate 2 mixed monomer, taken out immediately, and subjected to 60 kGy by a low energy accelerator. Irradiated. On the other hand, cast the irradiated latex on a glass plate,
A rubber film (opaque) that does not dry until it becomes transparent and has water remaining is soaked in a mixed monomer of the above composition, immediately pulled up, and irradiated with 60 kGy by a low energy accelerator,
Dry until clear. In this way, a hydrogel film was formed on the rubber surface by irradiation polymerization, leached with 1% ammonia water for 24 hours, air-dried until it became transparent, and then heat-treated at 80 ° C. for 1 hour. The adhesive strength was evaluated by an adhesiveness measuring device manufactured by Reska. After the cast latex was cast on a glass plate, the tackiness of the films having different drying times was 0.5 gf.

The adhesiveness measuring device was designed such that a rod-shaped sensor having a diameter of 5.1 mm was brought into contact with the sample to be measured at 30 mm / min and pressed with a load of 10 g for 10 seconds, and then the sensor was pulled up at the same speed to separate the sensor from the sample. It is represented by gf).

[0023]

Example 2 A radiation-fed natural rubber latex prepared in the same manner as in Example 1 was cast on a glass plate, and when water vaporized and strength appeared, the rubber film was peeled off from the glass plate and the weight ratio was changed. The adhesiveness was 0.2 gf, which was measured by immersing in a mixed monomer liquid of 8 acrylate / n-butyl acrylate 2 and immediately pulling up, irradiating with a 40 kGy low energy electron accelerator, and leaching and then heat treatment.

[0024]

Example 3 Radiation-fed natural rubber latex prepared in the same manner as in Example 1 was cast on a glass plate, and when water vaporized and strength appeared, the rubber film was peeled off from the glass plate and the weight ratio was changed. Immersion in a mixed monomer solution of 2-hydroxyethyl methacrylate 8 / 2-ethylhexyl acrylate 2 and immediately pulling up, irradiating with a 50 kGy low energy electron accelerator, leaching and heat treatment to measure the tackiness was 0.3 gf. It was

[0025]

[Comparative Example] The adhesive force of the rubber film produced in (Production of rubber film) was 28 gf.

Comparing Examples 1, 2, and 3 with Comparative Example,
It is apparent that the tackiness can be remarkably reduced by forming a hydrogel film on the surface of the rubber film according to the present invention.

[0027]

According to the present invention, by coating a mixed monomer consisting of a hydrophobic monomer and a water-soluble monomer on the surface of a rubber film and then irradiating it with an electron beam to form a hydrogel film on the surface. , Rubber film surface,
For example, it is possible to significantly reduce the surface tackiness of surgical rubber gloves, inspection rubber gloves, household rubber gloves, rubber gloves for protection against radioactive contamination, catheters, condoms, balloons, etc. Produce a different effect.

─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-5-230436 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08J 7/04 C08J 7/18

Claims (6)

(57) [Claims] 1. A method for preventing adhesion of a natural rubber latex film, which comprises coating a natural rubber latex film with a mixed monomer and then irradiating an electron beam to form a polymer film, wherein the mixed monomer is ethyl acrylate or n-acrylic acid. Radical-polymerizable hydrophobic monomer (1) consisting of propyl, n-butyl acrylate, i-butyl acrylate, 2-ethylhexyl acrylate, methylaminoethylminoethyl methacrylate, or diethylaminoethyl methacrylate
And acrylic acid, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, methacrylic acid, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, meta-N-vinylpyrrolidone, methoxyethyleneglycol methacrylate, methacryl Radical-polymerizable water-soluble monomer (2: acid methoxypropylene glycol, methoxypolyethylene glycol methacrylate, methoxyethylene glycol acrylate, methoxypropylene glycol acrylate, methoxypolyethylene glycol acrylate, polyethylene glycol dimethacrylate, or polyethylene glycol diacrylate) ) And a mixture thereof. 2. A polymer film formed by electron beam irradiation of a mixed monomer absorbs water.
The method described in. 3. The method according to claim 1, wherein the method of applying the mixed monomer to the natural rubber latex film is a dipping or spraying method. 4. The method according to claim 1, wherein the thickness of the polymer film is 5 to 100 μm. 5. The method according to claim 1, wherein the acceleration voltage of the electron beam is 500 kV or less. 6. A dose of 10 to 200 kG on the surface of the natural rubber latex film in electron beam irradiation after coating the mixed monomer on the natural rubber latex film.
The method of claim 1, wherein y is y.