JP7178120B2 - Photovulcanization of latex applied with different initiators - Google Patents

Description

The present invention is the beginning of latex used in the manufacture of products made of natural rubber (NR) latex material, such as catheters, bandages, or surgical control gloves, to prevent allergic reactions occurring in the user of the product. It relates to a method of applying photovulcanization with a second type of photoinitiator having a single component that exhibits both agent and thiol-ene cross-linking properties.

Vulcanization is defined as the three-dimensional bonding of polymer chains, cross-linking to help vulcanize materials to form a rubber together under temperature or light. Cross-linking properties are dependent on the amount, activity, and reaction time of the substances that effect vulcanization. Photovulcanization is the curing reaction of natural rubber under UV light with a thiol-ene cross-linker and photoinitiator system.

Light vulcanization has superior properties when compared to vulcanization, such as rapid cure and slow reaction rate, room temperature or minimal heat manufacturing. Furthermore, it is important that the chemicals and products used in this reaction have a low toxic effect.

In the known state of the art catheters, bandages or surgical control gloves are made of natural rubber (NR) latex material. Dip NR latex materials have important properties such as flexibility, resistance and recovery, but the rise in latex allergies that first occurred in users in the 1970's has made this property less important.

Allergy to NR latex products is due to type I latex hypersensitivity, natural rubber protein. Type IV latex hypersensitivity is caused by rubber additive substances. Contact-induced allergies are observed as nasal discharge and eye burning, redness after 24-96 hours of exposure to contact.

Sulfur vulcanization at 135-160° C. is required to convert the rubber into tire form. Substances that accelerate or slow down the reaction, as well as substances that increase resistance and hardness, plasticizers, softeners, anti-aging agents, inexpensive substances can mostly be added as additives to the rubber. Since the 1920s, dithiocarbamates and thioureas have been used as accelerators in sulfur vulcanization processes to lower reaction temperatures and shorten reaction times.

Current technology does not allow curing with peroxides or high-energy radiation (IR waves, γ-rays) due to concerns that accelerators present as residues, especially in medical and surgical gloves, can cause health problems. Attempts have been made to develop alternative cross-linking processes by various methods.

In recent years, laboratory-scale UV-curing latex formulations have been developed and have encountered problems such as fragile physical properties, high investment and manufacturing costs, and the use of acrylic monomers. Another method, the thiol-ene-reaction, UV prevulcanization of NR latex forms a new approach for manufacturing biocompatible surgical gloves without the use of catalysts.

The formulation formed as a result of photovulcanization includes latex, initiator, thiol-ene crosslinker and solvent. In the photovulcanization process, the use of an initiator and a thiol-ene cross-linking agent is critical, where the initiator interacts with UV light to achieve cure. To achieve photovulcanization, compounds containing 2-SH and 3-SH are used as thiol-ene crosslinkers. Most of these cross-linkers have a strong odor. Also, yellowing occurs as a result of achieving curing. The use of organic solvents as solvents presents another drawback in terms of green chemistry.

As a result, the above shortcomings and deficiencies require improvements in the related technical fields.

The present invention relates to photovulcanization of latex with different initiators to eliminate the above drawbacks and bring new advantages to the related technical field.

The object of the present invention is to apply photovulcanization with different initiators to the latex used in the manufacture of products to prevent allergic reactions occurring in users of products made from natural rubber (NR) latex materials. That is.

It is an object of the present invention to realize a photovulcanization process by using a single-component photoinitiator as a cross-linking agent by means of photopolymerization.

It is an object of the present invention to obtain products from latex materials that do not cause allergy problems by not using additional cross-linking agents and additives in the photovulcanization process.

It is an object of the present invention to provide a process for obtaining an eco-friendly latex by using water as solvent and by using odorless solutions and odorless synthetics.

To achieve the above objectives, the present invention relates to a method of applying photovulcanization with a second type of photoinitiator which has a single component and has both initiator and thiol-ene cross-linking properties. .

With the detailed description given below, the structural and characteristic features and all the advantages of the present invention will be understood in a clearer way and should be evaluated in view of this detailed description.

In this detailed description, photovulcanization is applied to the latex used in the manufacture of products made from natural rubber (NR) latex materials, along with different initiators, in order to prevent allergic reactions occurring in users of such products. The method of doing so is described with reference to examples only for a better understanding of the subject matter without forming any limiting effect.

The present invention relates to a method of applying photovulcanization with a second type of photoinitiator having a single component, which has both initiator and thiol-ene crosslinker properties.

Accordingly, the subject method includes the following steps:
A. dissolving 2-mercaptothioxanthone in distilled water;
B. adding the resulting 2-mercaptothioxanthone mixture to the latex;
C. mixing the resulting mixture until homogeneous;
D. coating a plate with the mixture obtained in step C);
E. Exposing the mixture coated on the plate to UV light to cure the mixture.

In the subject method, the 2-mercaptothioxanthone:latex ratio can have a value of 0.001:1 to 1:1.

In the subject method, steps B, C, D, and E are accomplished at room temperature.

From another aspect, the invention relates to a latex product obtained by a method according to the invention and provided with the above steps. The latex product differs from the latex products existing in the known state of the art in that the latex product does not contain allergy-causing compounds and therefore has an anti-allergic effect.

Another item of the invention is the use of latex free of allergenic photoinitiators obtained by the subject method for use in examination gloves, surgical gloves, adhesive bands, endotracheal tubes, epidural catheter injection adapters, condoms, etc. is used in the preparation of the products of

Within the scope of this specification, the word "COMPRISE" is intended to mean "COVER."

Where technically appropriate, the uses of the invention can be combined.

Applications are described herein in a manner that includes specific features/elements. This specification also covers other uses that include or consist of features/elements.

Technical references, such as patents and applications, are incorporated herein by reference.

A specific and explicitly stated use herein may form the basis of a disclaimer, either alone or together with one or more other uses.

The present invention will now be described with reference to the examples set forth below, for illustrative purposes only, and should not be construed as limiting the scope of the invention in any way.

How to apply photovulcanization to latex:
- Add 1 mL of distilled water to 2-mercaptothioxanthone (TXSH), weigh the initiator while changing grams, and dissolve in a beaker at room temperature.
- Add 2-mercaptothioxanthone (TXSH) dissolved in water to 5 grams of latex.
- The resulting mixture is mixed for 2 hours at room temperature using a magnetic stirrer.
- Coat the resulting formulation onto a glass plate.
- The formulation coated on the glass plate is then exposed to UV light by a UV curing device to achieve the curing process.

The subject method provides a vulcanization process.

Determination of the properties of the product obtained by the subject method:
- After the formulation is synthesized, FTIR spectra are utilized to determine the reaction capability of the subject method. After exposing the formulation to light for a defined period of time, an FTIR spectrum is obtained, the observed decrease in the peak at 1640 CM ⁻¹ is recorded, and a conversion calculation is performed.
- The mechanical properties of the film are determined at room temperature with a tension-stretching apparatus. A film of known thickness is cut with a dumbbell-type device.
- Tension (F) and extension (L) are recorded via the device. Force values and tensions are calculated according to Equations 1 and 2. A tension-elongation graph of the NR latex film is then drawn after the force values and tension are calculated.

Claims (5)

1. A method of photovulcanization applied to a latex together with a photoinitiator used in the manufacture of a product made of natural rubber (NR) latex material to prevent allergic reactions occurring in the user of said product, said method comprising: ,
A. dissolving 2-mercaptothioxanthone (TXSH) with initiator properties in distilled water;
B. adding the resulting mixture of 2-mercaptothioxanthone to a latex;
C. mixing the resulting mixture until homogeneous;
D. coating a plate with the mixture obtained in step c;
E. and exposing the mixture coated on the plate to UV light to cure the mixture. A photovulcanization application method according to claim 1, wherein said 2-mercaptothioxanthone is used as a photoinitiator. The photovulcanization application method according to claim 1, wherein the photovulcanization process uses UV-VIS illumination as the light source. A photovulcanization application method according to any one of the preceding claims, wherein the ratio of said 2-mercaptothioxanthone: said latex has a value between 0.001:1 and 1:1. A photovulcanization application method according to any one of claims 1 to 4, wherein steps B), C), D), E) are realized at room temperature.