JPS5921898B2 - Processing method for casein molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating casein molded articles.

More specifically, when all or most of the machining required to turn casein plastics into final products, which are obtained by hardening casein with formaldehyde, has been completed, PKa4
The present invention relates to a method for reducing formaldehyde liberated from a casein molded product, which is characterized by treating it with an aqueous solution of casein and an ammonium salt of an organic or inorganic acid. Conventional casein molded products are produced by hardening casein with formaldehyde, which is then processed through mechanical processing such as cutting, drilling, and polishing, as well as chemical processing such as polishing and dyeing, to produce buttons, accessories, buckles, seals, etc.
It was used for pen holders, margin jumpers, etc.

In the above products made by hardening casein with formalin, formaldehyde 5 and formaldehyde exist in the form of methylol, which does not contribute to hardening even if it reacts with casein. There is a concern that formaldehyde may cause pollution depending on the conditions of use. Especially pota 10
There is a risk that large amounts of formaldehyde transfer from dye to fibers will significantly reduce the commercial value, and it is desired to develop casein molded products that are free from this risk. However, no solution to this bookmaking problem is known at all. The 15 inventors of the present invention have completed the present invention as a result of intensive study on this problem. The casein molded product used in the present invention consists of casein (especially rennet casein), other natural artificial polymers, plasticizers, organic and inorganic fillers, acid 20 inhibitors, preservatives, stabilizers, and dyes. Cutting casein plastic fabric obtained by adding pigments and curing with formaldehyde alone or in combination with formaldehyde and other curing agents such as trioxane and glyoxal.
Products that undergo all or most of the machining processes such as drilling and polishing are processed into final products such as buttons, brooches, necklaces, other accessories, buckles, seals, pen holders, mahjong pies, etc.

Examples of the ammonium salt of an organic or inorganic acid with a PKa of 4 or higher used in the present invention include ammonium carbonate, ammonium bicarbonate, ammonium carbamate, ammonium acetate, ammonium propionate, ammonium citrate, and ammonium succinate.

35 Furthermore, as the casein, milk casein such as rennet casein and acid casein is suitable.

The treatment of the present invention is generally carried out by immersing the casein molded article to be treated in an aqueous solution of the treatment agent.

The concentration of the above treatment agent in the aqueous solution is affected by the amount of formaldehyde remaining in the casein molded product, but P
Organic acid or inorganic acid ammonium salt with Ka4 or higher is 10%
0.05% (% is weight %, the same applies hereinafter), preferably 5% to 0.1%. Also, casein is 0.5% to 0.00
A concentration range of 1%6 preferably 0.1 to 0.01% is preferred. If the concentration exceeds the above range, the casein molded product may be colored, cracks may occur in severe cases, and slight blocking may occur, which may cause undesirable effects.
Further, below this concentration range, the effect of reducing formaldehyde is inferior and a long treatment time is required. Further, within the above-mentioned preferred range, almost no change in hue occurs when dyeing with an acidic dye after this treatment. In practicing the present invention, it is desirable to perform polishing using a bath solution of an oxidizing agent such as hypochlorite or hydrogen peroxide.

Such polishing alters the surface of the casein molded product, aids in the penetration of the treatment agent, and reduces formaldehyde released in a short period of time. Since polishing is a chemical change in the very surface layer of a casein molded product, it is effective to carry out the present invention immediately after polishing, or at least within 24 hours. After a long period of time, the reduction in formaldehyde remains at the same level as when no polishing was applied.

When dyeing with ordinary acid dyes after carrying out the present invention, it is preferable to wash thoroughly with water before dyeing. This is to prevent slight differences in dyed feet, color tone, etc. from those of untreated products.Of course, the method of the present invention can be carried out even after dyeing, as long as you are willing to undergo slight changes in color tone. Of course, steam treatment and drying. There is no problem in removing formaldehyde from casein molded products in advance, such as aging by long-term storage. Although the processing temperature and time in the present invention are interrelated, the processing temperature is generally 5 to 50°C, preferably 10°C to 50°C.
The temperature is 0 to 40°C. If the temperature is too high, the amount of formaldehyde may increase due to excessive hydrolysis if the curing is not complete, which is undesirable, and if the temperature is too low, it takes too much time. The time usually ranges from 1 hour to 4 days. In casein molded products obtained by this method, the amount of formaldehyde released is greatly reduced, and at the same time, mechanical strength, stability, and chemical changes due to water, sweat, etc. are exactly the same as conventional products. .

Furthermore, the amount of formalin released decreases with the number of days, and if the product is aged for a long period of time, dye transfer and release of formaldehyde can be completely prevented. When an organic or inorganic ammonium salt with a PKa of 4 or higher and casein are used at the same time, the removal effect becomes greater and the reproducibility of the effect improves, making it possible to use the solution many times. The excellent effect of the present invention is that the organic or inorganic ammonium salt with a PKa of 4 or more and water cause hydrolysis of free formaldehyde and methylolated formaldehyde in the casein molded product, and have the effect of eluting formaldehyde into the immersion liquid. Casein partially reacts with these formaldehydes, but a very thin polymer film is formed on the surface of the casein molded product, and even after the treatment of the present invention is carried out, it reacts with formaldehyde that diffuses from inside to some extent, causing free release. It is understood that it has the effect of preventing the scattering of formaldehyde.

Since the casein film on the surface has a high chemical affinity with the hardened casein molded product, it is presumed that the physical and chemical properties will not be impaired compared to untreated products. Examples and comparative examples of the present invention will be shown below, but the present invention is not limited to the embodiments of these examples.

Examples 1 to 5, Comparative Examples 1 to 2 100 slices of bone white fabric (white) made from rennet casein with a diameter of 30.5 mm and a thickness of 51.11 mm were soaked in 5% formalin to serve as button prototypes. It was immersed in 1000 parts of an aqueous solution and cured at room temperature for 14 days.

During this time, the hardening solution was stirred occasionally. Thereafter, the sample was taken out, washed with water, and then dried with warm air at 400 to 50°C for 24 hours. Diameter 30111 Thickness 2
．． A 5m1I, 4-hole button was created. Next, the test button was immersed in 300 parts of a 2-fold diluted solution of Lactopol (sodium hypochlorite aqueous solution manufactured by Daicel Corporation) at 40°C for 5 minutes to polish it, and then washed twice with water and drained. Got the sample. The next treatment was carried out 15 hours after this treatment. 300 parts of an aqueous solution of 3% ammonium acetate and 0.01% rennet casein was kept at 40° C., and the test button sample was immersed for 24 hours.

After washing the button sample with water and draining the water, eluted formaldehyde was measured using the test method listed in Appendix Table 1 of Ministry of Health, Labor and Welfare No. 34, and 253 ppm of formaldehyde was found to be eluted. The untreated one had a concentration of 1720 ppm. When dyed red, yellow, and blue with an acid dye without any change in hue, no difference in color tone was observed compared to the untreated sample. The formaldehyde elution test was conducted on the string again one month later, and the result showed that the formaldehyde elution concentration had decreased to 187 ppm. The table below shows the results of similar treatments using different drugs and conditions. When the treatment of the present invention was applied to the material without polishing under the conditions of Example 1, the result was 480.

Claims (1)

[Claims] 1. At the stage when all or most of the mechanical processing necessary to make casein plastics into a final product has been completed, 0.05 to 10% by weight of an ammonium salt of an organic or inorganic acid with a PKa of 4 or more and 0.001 to 0.5% of casein are added. A method for reducing formaldehyde liberated from a casein molded article, the method comprising immersing it in an aqueous solution containing % by weight.