JPS5829325B2 - Surface treatment agent for molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface treatment agent for molded products such as synthetic resins and metals, and more particularly to a surface treatment agent for improving various physical properties such as surface hardness and scratch resistance of molded products. It is something.

Among synthetic resin molded products, cellulose acetate resin, methacrylate ester resin, etc. have excellent properties such as beautiful appearance and processing performance, but their surface hardness is low, easily scratched, easily abraded, and have poor boiling water resistance. It has various drawbacks, such as poor chemical resistance.

In order to improve such surface characteristics, a method of coating the surface with a treatment agent can be considered.

In general, the functions required of a surface treatment agent are (1) excellent adhesion to the object to be treated, (2) increased surface hardness,
Able to impart wear resistance and scratch resistance; (3) ability to impart or not impair transparency, smoothness, water resistance, chemical resistance, etc.; and (4) use a solvent that does not attack the object itself. thing,(
5) The coating process can be easily and uniformly performed using a normal coating method.

However, to date, no material has been found that adheres well to cellulose acetate resin, methacrylate ester resin, etc. and has all the functions necessary as the above-mentioned surface treatment agent. Currently, it is used as a surface treatment agent, but this treatment agent inevitably attacks the underlying surface.

The present inventor conducted multifaceted research regarding surface treatment agents for cellulose acetate and other resins in order to use a solvent that does not attack the polymer and to obtain a surface treatment agent that has all the functions necessary as a surface treatment agent. As a result, the present invention was completed.

That is, an object of the present invention is to provide a surface treatment agent having the above properties.

To outline the present invention, the present invention has an average molecular weight of 200
A polyurethane resin and alcohol-based polyurethane resin having a weight average molecular weight of 30,000 to 150,000 obtained by reacting 1 mol of a polyol having a molecular weight of 1,500 to 1,500, 4 to 12 mol of an alicyclic diisocyanate, and 3 to 11 mol of a diol having 2 to 6 carbon atoms. This invention relates to a surface treatment agent for molded products made of a solvent.

If the surface treatment agent of the present invention is applied to the surface of a synthetic resin or metal molded product using an appropriate coating method, dried if necessary, and then heat-cured, the coating film will have good adhesion to the molded product and will have good hardness. A film with high abrasion resistance and scratch resistance is formed, and the film also has excellent transparency (translucency), smoothness, boiling water resistance, and chemical resistance.

Further, this surface treatment agent can be easily and uniformly applied by commonly used coating methods such as spray coating, electrostatic coating, dip coating, and brush coating.

Furthermore, since this treatment agent uses an alcohol-based solvent as a solvent, it can be suitably used for plastics that are easily attacked by general organic solvents, such as cellulose acetate resin.

The invention will now be described in more detail.

The specific polyurethane resin that is the main component of the surface treatment agent used in the present invention is: (1) 1 mol of polyol having an average molecular weight of 200 to 1,500, (2) 4 to 12 mol of alicyclic diisocyanate, and (3)
) Obtained by reacting 3 to 11 moles of diols having 2 to 6 carbon atoms in an organic solvent.

The polyol component used in the production of the polyurethane resin of the present invention must have an average molecular weight of 200 to 1,500.

That is, when the average molecular weight is less than 200, the polyurethane resin obtained from this polyol becomes poorly soluble in a solvent and becomes difficult to handle.

On the other hand, if it is more than 1500, the surface treatment agent cannot have the required function.

Examples of polyols having an average molecular weight of 200 to 1,500 include polyesters, polyethers, and polyester polyethers having hydroxyl groups.

Polyesters include polyhydric alcohols such as ethylene glycol, propylene glycol, 6-hexanediol, trimethylolpropane, sorbitan, etc. and polyhydric carboxylic acids such as succinic acid, adipic acid, etc.
Examples include condensates of fumaric acid, glutaric acid, isophthalic acid, pyromellitic acid, etc., condensates of hydroxycarboxylic acids and polyhydric alcohols, and lactone polymers.

As the polyether, for example, polyethylene glycol, polypropylene glycol, etc. can be used.

In addition, polyester-polyethers include polyesters obtained by addition polymerizing alkylene oxide to the above-mentioned polyesters,
Polyester-polyether having a hydroxyl group at the terminal, which is a condensation of polyether and polycarboxylic acid, can be used.

Furthermore, some of these polyols can be replaced with low molecular weight diols.

However, the ratio of polyol and diol must be such that the average molecular weight of the two used does not become less than 200.

Diols such as ethylene glycol, diethylene glycol, propylene glycol, 1,4-butanediol, and 1,6-hexanediol are used as the low molecular weight diol.

As the incyanate compound, an alicyclic diisocyanate is used, but in some cases, a mixture with an aromatic diisocyanate can also be used.

When used as a mixture, the aromatic diisocyanate is limited to 30 moles more than the alicyclic diisocyanate.

This is because if the amount exceeds 30 mol, it becomes poorly soluble in alcoholic solvents.

Alicyclic diisocyanates include isophorone diisocyanate, tolylene diisocyanate, hydrogenated xylylene diisocyanate, hydrogenated diphenylmethane diisocyanate, etc., while aromatic diisocyanates include 4,4' diphenylmethane diisocyanate, 2
, 4- and 2,6-tolylene diisocyanate, m-
Xylylene diisocyanate etc. can be used.

To describe in detail the method for producing the polyurethane resin which is the main component of the surface treatment agent according to the present invention, alicyclic diisocyanate alone or optionally is added to 1 mole of polyol having an average molecular weight of 200 to 1500 in the reaction solvent. A method is adopted in which 4 to 12 moles of a mixture with an aromatic diisocyanate and 3 to 11 moles of a diol having 2 to 6 carbon atoms are blended, a catalyst is added, and the temperature is raised as the reaction progresses. Heat and stir at ~100°C for 3 to 12 hours.

Then, when the reaction has progressed and the viscosity has changed to an appropriate level, a diol having 2 to 6 carbon atoms is added to stop the reaction,
This method involves adding a diluting solvent to form a diluted solution.

However, this is just an example, and the present invention is not particularly limited to this method.

In the above reaction, the reason why the proportion of alicyclic diisocyanate used is 4 to 12 moles is that if it is less than 4 moles, the photoresistivity and hardness of the formed film will decrease, and its function as a surface treatment agent will be lost. On the other hand, if it is more than 12 moles, it will be difficult to dissolve in alcoholic solvents, and it will have poor fluidity as a surface treatment agent, resulting in problems in painting, and the resulting film will only be hard and brittle.

Diols having 2 to 6 carbon atoms include ethylene glycol, propylene gelol, 1°4-butanediol, 1,6-hexanediol, diethylene glycol, cyclohexanediol, 2,4-dimethyl-2
-(Hydroxyethoxymethyl)-1,5-bentanediol, jetanolamine, N-methyljetanolamine, 3゜6-dimethyl-4-octyne-3,6-diol, 2,5-dimethyl-3-hexyne- Diols such as 2,5-diol can be used.

The reaction solvent may be selected from any combination of those commonly used as dissolving agents for urethane resins, such as dimethylformamide, diethylformamide, dimethylacetamide, acetone, methyl ethyl ketone, dimethyl sulfoxide, methyl ethyl ketone, diochirin, and tetrahydrofuran. .

It is preferable to use an alcohol-based diluting solvent.

Usually alcohols having 1 to 6 carbon atoms, preferably 2 to 5 carbon atoms, such as methanol, ethanol, furopanol,
These include isopropanol, butanol, isobutanol, tertiary butanol, amyl alcohol, β-oxymethyl ether, β-oxyethyl ether, ethyl glycol monobutyl ether, and the like.

Of course, a mixture of these solvents (for example, butyl alcohol and ethylene glycol monobutyl ether) can also be used.

Further, other solvents such as toluene, xylene, dioxane, ethyl acetate, methyl ethyl ketone, ethyl ether, and acetic acid may be used within a range that does not attack the synthetic resin base material of the object to be coated.

The reason why the polyurethane resin surface treatment agent of the present invention has the above functions and has excellent adhesive properties is as follows.

That is, since the polyol component of the polyurethane resin has an average molecular weight of 200 to 1,500, and a low molecular weight diol is used for chain extension, the produced polyurethane resin has a low molecular weight, and the average molecular weight of the polyurethane resin is 200 to 1,500. The average number of urethane bonds contained is 4.
This is because it is present in an amount of 0 to 6.0 moles.

Normally, commonly prepared polyurethane resins have a molecular weight of 1
The amount of urethane bonds contained per ooo is about 2 moles at most, and it is not soluble in alcoholic solvents, so it is particularly unsuitable for use as a surface treatment agent for synthetic resin molded products.

On the other hand, when diamines are used as a chain extender, urea bonds are formed, resulting in poor adhesion to the substrate, which is not suitable for the present invention.

The surface treatment agent of the present invention is used by diluting the above polyurethane resin with an alcoholic solvent to a resin concentration of 3 to 20% by weight.

The synthetic resin surface treatment agent of the present invention thus obtained can be used for surface treatment of various synthetic resins or metals.

For example, it is used with an appropriate coating method to treat the surface of synthetic resins such as polycarbonate, polymethyl methacrylate, polystyrene, acrylonitrile-styrene copolymer, hard polyvinyl chloride, and metals such as iron, steel, and aluminum. Leave to dry at room temperature for ~10 minutes.

write! The coating film obtained in step - is heated and dried at a temperature of about 30 to 150°C, preferably about 40 to 80°C, for about 3 to 10 minutes to form a film.

At this time, the heating temperature is desirably the softening temperature of the synthetic resin base material, and if the heating temperature is high, baking may be performed for a short time, and if the heating temperature is low, baking may be performed for a long time.

A coating thickness of about 3 to 5 microns is usually sufficient.

If the coating is thinner than the above range, the desired improvement in surface hardness will not be observed, and if the coating is thicker than the above range, peeling of the coating will easily occur during molding, which is not preferable.

Furthermore, if a usual acid catalyst such as P-toluenesulfonic acid, phosphoric acid, hydrochloric acid, boric acid, sulfuric acid, tartaric acid, maleic anhydride, etc. is added to the surface treatment agent according to the present invention in advance, it can be used at low temperature and in a short time. Burning can be done with .

Before applying the surface treatment agent according to the present invention to a synthetic resin base material, the surface can be pretreated by well-known means such as detergent, alkali, alcohol, dichromic acid mixture, etc., resulting in favorable coating adhesion. give.

The film obtained in this way has good adhesion to the synthetic resin, high hardness, and excellent abrasion resistance, abrasion resistance, and scratch resistance, and the transparency of the synthetic resin itself (translucency). ), and also has excellent properties such as boiling water resistance, acid resistance, and alkali resistance.

Next, production examples of raw materials, examples, and comparative examples will be given and explained.

However, in these examples, "department" and "department" are based on weight unless otherwise specified.

Example-1 Add polyester (adipic acid and l) to the reaction vessel.

315 parts (0.5 mol) of 4-butanediol having an average molecular weight of 630, 666 parts (3 mol) of inphorone diisocyanate, 190 parts of 1.4-butanediol
Methyl ethyl ketone was blended so that the solid content was 60 parts (2.1 mol) and the solid content was 60 parts by weight.

To this was added 0.5 part of dibutyltin silaurylate as a catalyst, and the mixture was heated and stirred at 80° C. for 7 hours.

1 when the viscosity reaches 70,000 CPS/60℃
, 4-butanediol was added to stop the reaction.

The obtained polyurethane resin contained 5 moles of urethane bonds per 1000 molecular weight.

Next, ethylene glycol monobutyl ether was added to make the solid content 50% by weight, and isopropyl alcohol was further added to prepare a surface treatment agent having a solid content of 10% by weight.

The viscosity of this treatment agent was 30 Cps/30°C.

Comparative Example 1 The same method as in Example 1 was carried out except that 2 mol of inphorone diisocyanate and 1 mol of 1,4-butanediol were used, and a surface treatment agent with a solid content of 1O was used. was prepared.

The obtained polyurethane resin contained 3.1 moles of urethane bonds per 1000 molecular weight.

Comparative Example 2 Cellulose acetate with a degree of acetylation of 55% was dissolved in methyl acetate,
A surface treatment agent was prepared with a solid content of 10% by weight.

The surface treatment agents obtained in Example 1 and Comparative Examples 1 and 2 were applied to eyeglass frames made of cellulose acetate by dip coating, and after draining, they were heated and dried at 60° C. for 5 minutes.

The results of testing the performance of the resulting film are shown in Table 1 below.

Example-2 Polyether (having an average molecular weight of 800) in the reaction vessel
1 mol, inphorone diisocyanate 3.2 mol, 4.
0.8 mol of 4'-diphenylmethane diisocyanate,
Three moles of ethylene glycol and dioxane were blended so that the solid content was 60% by weight, and the mixture was heated and stirred at 70°C for 8 hours.

Ethylene glycol was added as a reaction terminator when the viscosity reached 80,000 CPU/60°C.

The obtained polyurethane resin contained 4.2 mol of urethane bonds per 1000 molecular weight.

Next, β-oxyethyl methyl ether was added to make the solid content 50% by weight, and isopropyl alcohol was further added to dilute the solid content by 15% by weight to prepare a surface treatment agent.

The viscosity of this treatment agent was 80 CPS/30°C.

Example-3 Polyester polyether (average molecular weight 1o
oo) i mol, 10 mol of hydrogenated compound of 4.41-diphenylmethane diisocyanate, 9 mol of 1,6-hexanediol and dimethylformamide at a solid content of 6
The mixture was blended so as to have a weight of 0, and heated and stirred at 80° C. for 8 hours.

1. When the viscosity reaches 100,000 CPS/60°C.
The reaction was stopped by adding 6-hexanediol.

The obtained polyurethane L/tan resin contained 4.3 moles of urethane bonds per 100 molecular weight.

Then, ethylene glycol monobutyl ether was added to dilute the solid content by 3 weights to prepare a surface treatment agent.

The viscosity of this treatment agent was 10 CPS/30°C.

The surface treatment agents prepared in Examples 2 and 3 above were applied to an iron plate and an acrylic resin plate.

The results of testing the performance of the resulting coatings are shown in Table 2 below.

Claims (1)

[Claims] 1 Polyol 1 having an average molecular weight of 200 to 1500
weight average molecular weight of 30,000 to 150,000 obtained by reacting 4 to 12 moles of alicyclic diisocyanate and 3 to 11 moles of diols having 2 to 6 carbon atoms.
A surface treatment agent for molded products made of a polyurethane resin and an alcohol solvent.