JPH01144498A - Polyurethane-removing agent - Google Patents

Abstract

PURPOSE:To provide a novel removing agent containing dimethyl sulfoxide and an organic solvent, having excellent peeling performance of a polyurethane firmly attached to a mold of lens, etc., made of glass, metal, etc., and free from problems of apparatus corrosion. CONSTITUTION:The objective removing agent contains (A) dimethyl sulfoxide and (B) an organic solvent composed of halogenated hydrocarbon (e.g., methylene chloride, trichloroethylene, perchloroethylene and 1,1,1-trichloroethane), an aromatic hydrocarbon (e.g., benzene, toluene or xylene), etc., at a volume ratio (A/B) of 10/90-90/10, especially preferably 20/70-70/20.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polyurethane remover that firmly adheres to molds made of glass, metal, etc. when manufacturing polyurethane molded products such as polyurethane lenses. The present invention relates to a polyurethane remover suitable for removing polyurethane.

[Prior art and its problems] In the production of polyurethane molded products, if polyurethane remains in the mold after the resulting polyurethane molded product is released from the mold, mold set-up and transferability of the mold may be affected in the next molding operation. This causes problems and makes it impossible to obtain a molded product in the desired shape.

Therefore, polyurethane remaining on the mold is removed physically or mechanically, but scratches are a problem with mirror-finished molds that require precise transferability.
This problem is particularly serious in molds made of glass or the like with low surface hardness.

Therefore, as a chemical method for removing polyurethane, for example, strong acids such as sulfuric acid and concentrated nitric acid are used. There is also a risk that equipment etc. will be corroded. Although considerable effects have been recognized by changing materials to prevent corrosion, it is not perfect, and it may be difficult to incorporate complex mechanisms into equipment. Furthermore, the use of acid-resistant equipment results in an increase in equipment costs.

Additionally, unnecessary polymers have been removed from molds using solvents with high polymer solubility, such as methylene chloride, dichloroethane, carbon tetrachloride, trichlorethylene, perchlorethylene, and aromatic compounds. Although this method is easier in terms of equipment than using the above-mentioned strong acid, if the polymer to be removed is polyurethane, etc., which has a high crosslinking density and strong adhesiveness, it can be peeled off in a short time. #I can't leave.

Generally, a mixture of methylene chloride and a strong acid is used as a stripping agent for polyurethane and epoxy paints, but since it contains a strong acid, there remains the problem of corrosion of equipment. Furthermore, there are stripping agents that contain phenol to strengthen stripping power while reducing corrosivity, but as is well known, phenol is acutely and chronically toxic and has a negative impact on the working environment and external environment. Prevention equipment requires a large amount of money.

The purpose of the present invention is to eliminate the drawbacks of the conventional polyurethane remover mentioned above, to provide a polyurethane removal agent that has excellent polyurethane peeling force, and that does not cause corrosive problems for manufacturing equipment for polyurethane molded products.
An object of the present invention is to provide a new polyurethane removing agent.

[Means for solving the problem] The present invention has been made to achieve the above object, and the polyurethane removing agent of the present invention is characterized in that it contains dimethyl sulfoxide and an organic solvent.

The present invention will be explained in detail below.

In the polyurethane removing agent of the present invention, the essential components are dimethyl sulfoxide and an organic solvent. As this organic solvent, halogenated hydrocarbons are preferably used, and representative examples thereof include methylene chloride, trichloroethylene, perchloroethylene, 1°1.1-)lichloroethane, but of course, the solvent is not limited to these. It's not something you can do.

Aromatic hydrocarbons can also be used as organic solvents, typical examples of which include benzene, toluene, xylene, etc., but of course the solvent is not limited to these. These organic solvents may be of the same type (eg, halogenated hydrocarbons or aromatic hydrocarbons) or different types (halogenated hydrocarbons and aromatic hydrocarbons).

The ratio of dimethyl sulfoxide/organic solvent is 1 by volume.
It can be varied over a wide range of 0/90 to 90/10. A particularly preferred ratio is 20/70 to 70/20.

The polyurethane removing agent of the present invention may contain other additives in addition to dimethyl sulfoxide and the organic solvent, if necessary. Examples of these include surfactants such as alkylbenzene sulfonates, α-olefin sulfate ester salts, alcohol sulfate ester salts, alcohol ethylene oxide adducts, and fatty acid jetanolamide; salts such as sodium phosphate and sodium silicate; pyridine, Examples include amines such as triethanolamine and triethylamine; polyhydric alcohols such as glycerin and ethylene glycol.

Examples of the polyurethane that can be removed by the removing agent of the present invention include polyurethanes obtained by reacting polyisocyanates with polythiols or polyols.

The polyisocyanate used to obtain the above polyurethane is not particularly limited, but includes tolylene diisocyanate, diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, naphthylene diisocyanate, tolylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylene diisocyanate, hydrogenated Xylene diisocyanate, hydrogenated diphenylmethane diisocyanate, lysine diisocyanate, triphenylmethane triisocyanate, tris(incyanate phenyl) thiophosphate, trans-cyclohexane 1,4-diisocyanate, p-phenylene diisocyanate, tetramethylene diisocyanate, 1,6.11- Undecane triisocyanate, 1,8-diisocyanate-4-
Polyisocyanate compounds such as isocyanate methyl octane, lysine ester triisocyanate, 1,3,6-hexamethylene triisocyanate, bicycloheptane triisocyanate, and allophanate modified products, biuret modified products, isocyanurate modified products, polyols or polythiols of these compounds Examples include adduct modified products of
It may also be a mixture of more than one species.

Other known isocyanate compounds may be used, but the isocyanate compound serving as the main component must be bifunctional or higher. A halogen atom such as CI or Br may be introduced into a known aromatic isocyanate compound. Particularly preferred isocyanate compounds include non-yellowing isocyanate compounds represented by xylene diisocyanate, isophorone diisocyanate, hexamethylene diiso, and cyanate.

Furthermore, the polythiol used in the reaction with the polyisocyanate is not particularly limited, and any known polythiol can be used. For example, ethanedithiol, propanedithiol, propanetrithiol, butanedithiol,
Pentanedithiol, hexanedithiol, heptanedithiol, octanedithiol, cyclohexanedithiol, cycloheptanedithiol, 2,5-dichlorobenzene-1,3-dithiol, pentaerythritol tetrakis 3-mercaptopropionate, pentaerythritol tetrakis thioglycolate, etc. Pentaerythritol derivatives are particularly preferred.

The polyol is not particularly limited, but propylene glycol, glycerin, hexanetriol, diglycerin, pentaerythritol, polyethylene glycol, and the like are preferred.

The polyurethane remover of the present invention is used as follows. That is, the mold and tools to which polyurethane is attached are immersed in a polyurethane remover. Removal of the polyurethane may be facilitated by ultrasonic vibration during soaking. Further, the polyurethane remover of the present invention may be applied only to the portions of the mold and tools to which polyurethane is attached.

As is clear from the Examples described below, the polyurethane remover of the present invention not only has excellent polyurethane peeling power but also has the advantage of not being corrosive to metals.

In addition, in the polyurethane remover of the present invention, polyurethane is removed by peeling rather than dissolving it, so it is easy to separate polyurethane from the polyurethane remover after peeling treatment, and the service life of the polyurethane remover is also shortened. Not only can it be used repeatedly for a long time, but it also has the advantage that it can be easily recovered by distillation or the like.

[Examples] Examples of the present invention are shown below, but the present invention is not limited to these Examples.

(Example 1) m-Q silane diisocyanate...100g Pentaerythritol tetrakis 3-mercaptopropionate...143g Di-n-butyl phosphate......・・・・・・
・6.05g dibutyltin dilauric acid・・・・・・
...0.24g2 (2'-hydroxy-5'-
t-octylphenyl)benzotriazole・・・・・・
・・・・・・・・・・・・・・・ 0.48g The above mixture was stirred uniformly, and after fS, it was placed in a mold consisting of a resin gas get and a glass mold, and heated from 25°C to 120°C for 22 hours. and heated to obtain a polyurethane molded product. At this time, dimethyl sulfoxide (DMS) is used to remove water droplets of polyurethane adhering to the outside of the glass mold and the thin film of polyurethane that has formed near the contact surface between the glass mold and the resin gas get.
The polyurethane was immersed in a removing agent containing a mixture of O> and methylene chloride at a volume ratio of 1:2, and the peeling state of the polyurethane and metal corrosion were observed. The results are shown in Table 1.

(Examples 2 to 8) Adhesive cured polyurethane was treated with DMSO in the same manner as in Example 1.
The polyurethane was mixed with various solvents and immersed in an fs remover, and the peeling state of the polyurethane and metal corrosivity were observed. In addition, Example 2
In Examples 3 to 8, unlike in Example 1, ultrasonic vibrations were applied, although as in Example 1, ultrasonic vibrations were not applied.

The results are shown in Table 1.

(Examples 9-10) A polyurethane molded article was obtained in the same manner as in Example 1 except that O, Olg of polyethylene glycol (average molecular weight 200) was further added to the monomer mixture of Example 1. At this time, the polyurethane that had adhered and hardened to the glass mold and the tool was immersed in a remover mixture of DMSO and various solvents, and ultrasonic vibration was applied to observe the peeling state of the polyurethane and metal corrosion. The results are shown in Table 1.

(Comparative Examples 1 to 5) Same as Example 1 except that a polyurethane remover other than the polyurethane remover of the present invention was used,
Adhesive and hardened polyurethane was immersed and subjected to ultrasonic vibration to observe the peeling state of the polyurethane and metal corrosion. The results are shown in Table 1.

(The following is a blank space) From Table 1, the polyurethane remover of this example is compared to Comparative Examples 1-
Polyurethane M has superior releasability compared to the conventionally known one shown in No. 5.

Furthermore, the conventionally known remover shown in Comparative Example 6 has excellent polyurethane stripping properties but is highly corrosive to metals, and in this respect as well, the remover of this example, which is not corrosive to metals, is superior.

Further, the removers of Examples 1 to 7 and 9 to 10, which are composed of dimethyl sulfoxide and chlorinated hydrocarbon, are non-flammable and are excellent in this respect as well.

Furthermore, as is clear from Examples 1 and 2, the polyurethane remover of the present invention is also excellent in that polyurethane can be removed to a satisfactory degree even without applying ultrasonic vibration.

"Effects of the Invention" As described above, the polyurethane remover of the present invention can effectively remove polyurethane from molds and jigs with complex shapes, and can corrode molds, jigs, and their auxiliary equipment and equipment. It can be used without

Claims (2)

[Claims] (1) A polyurethane removing agent characterized by containing dimethyl sulfoxide and an organic solvent. (2) The polyurethane removing agent according to claim 1, wherein the organic solvent is a halogenated hydrocarbon, an aromatic hydrocarbon, or a mixture thereof.