JPH0367107B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for reinforcing a protective body for reinforcing the surface of a foam molded article, and particularly to a method for strengthening a protective body with excellent cushioning properties by reinforcing it with a polyurethane layer.

Foamed synthetic resin molded products are advantageous in terms of cost because they can increase the expansion ratio, and at the same time, because they have a low density, the molded products are lightweight and extremely easy to handle. Protective boxes for packaging various products as they also have cushioning and insulation properties; Containers for transporting fresh foods such as fish, vegetables, and meat in cold storage; Protective clothing such as helmets, winter clothing, and diving wet suits; It is also widely used as a protective body for various other purposes.

However, these foamed molded products have a low load-bearing capacity, making them unsuitable for heavy products, and also have a problem of being easily damaged by friction or collision due to their low surface strength.

In order to improve these problems, methods have been used to increase rigidity and load-bearing capacity by bonding thin structural materials to the surface, but this method is complicated and cannot be mass-produced for products with complex shapes. The disadvantage was that the processing cost was high. Another method is to apply paint to the surface of the molded product and let it harden and dry, but this method requires a long time to harden, and the paint before hardening can cause the foamed synthetic resin to swell. Dissolve in. Furthermore, since foamed synthetic resins generally have small pores on their surface that communicate with the air bubbles inside, the paint penetrates into the pores and causes pinholes in the cured coating.

Since the conventional methods have various drawbacks as described above, the present inventors conducted various studies to improve these drawbacks, and as a result, they arrived at the present invention.

That is, the present invention provides the outer surface of the foamed synthetic resin molded product,
A method for strengthening a foamed protector, which comprises spraying the following room temperature curing highly reactive polyurethane source solution onto the surface of the protector at a discharge pressure of 30 to 210 kg/cm ² using a high-pressure spraying device.

(A) A base material containing one or a mixture of two or more selected from the group of diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, or modified products thereof; (B) 50% primary hydroxyl group; a curing agent with a hydroxyl value of 10 to 380 mgKOH/g, which contains 50% or more of a polymer polyol with a hydroxyl value of 100 mgKOH/g or less; (C) aliphatic or aromatic polyamines; a crosslinking agent containing one or a mixture of two or more selected from the group of alcohols or alkanolamines; (D) tertiary amines or organometallic compounds alone or in a mixture of two or more; The catalysts A to D have an equivalent ratio (NCO/H) of the isocyanate group of the organic polyisocyanate to the active hydrogen in the polyol and crosslinking agent of 0.9 to 1.30,
The catalyst is 0.001 to 0.001 to the total amount of raw materials (A to C)
Room temperature curing highly reactive polyurethane stock solution containing 5% by weight.

According to the present invention, the surface layer can be completed simply by spraying the stock solution at high pressure, so that the rigidity of the foamed molded product can be extremely easily increased and the load-bearing capacity can be increased. Furthermore, even complex shapes can be finished with simple work, making mass production possible. Furthermore, in the present invention, since the stock solution hardens in more than ten seconds, there is almost no risk that the stock solution will swell, dissolve, or penetrate into the foamed molded article. The urethane elastomer obtained by hardening the raw solution has high strength and high wear resistance, so it can prevent damage to the protector due to friction, collisions, etc.

In the present invention, for example, Glass Craft's RIM series and Propler T-3A,
Using a high-pressure spraying device such as Gasmer Model H-, the polyurethane stock solution is sprayed onto the surface of the protector at a discharge pressure of 30 to 210 kg/cm ² . Increasing the strength of a urethane elastomer often involves increasing the viscosity of the polyurethane stock solution, but according to the present invention, even a highly viscous stock solution turns into fine particles, making it possible to obtain a smooth construction surface. Another major feature of the present invention is that it does not require a viscosity-reducing solvent, which is required when a normal low-pressure spraying device is used, so thick coating can be achieved with one spraying.

Examples of the foamed synthetic resin used in the present invention include foamed polystyrene, foamed polyurethane, foamed polyethylene, foamed phenolic resin, and sponge rubber.

The organic polyisocyanate used in the present invention is, for example, 2,4-tolylene diisocyanate, 2,6
-Tolylene diisocyanate and mixtures thereof (TDI), diphenylmethane-4,4'-diisocyanate (MDI), xylylene diisocyanate (XDI), dicyclohexylmethane-4,4'-diisocyanate (hydrogenated MDI), isophorone diisocyanate (IPDI) ), hexamethylene diisocyanate (HDI), hydrogenated xylylene diisocyanate (HXDI), crude TDI, polymethylene polyphenyl polyisocyanate (crude MDI), and isocyanurate-modified products, carbodiimidation-modified products of these isocyanates, and piuretsu. These include chemically modified products.

Among these organic polyisocyanates, MDI,
Crude MDI and its modified products are particularly preferred.

The polyol used in the present invention is an addition polymerization of one or more alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide to polyhydric alcohols such as water, ethylene glycol, propylene glycol, glycerin, trimethylolpropane, and pentaerythritol. This is a polyether polyol obtained by

In addition to the above, polyester polyols obtained by reacting polycarboxylic acids with low molecular weight polyols, polyester polyols obtained by polymerizing caprolactone, and higher fatty acid esters containing OH groups such as castor oil can also be used. Furthermore, a polymer polyol obtained by graft polymerizing an ethylenically unsaturated compound such as acrylonitrile, styrene, or methyl methacrylate to the above-mentioned known polyether polyol or polyester polyol;
2- or 1,4-polybutadiene polyols or hydrogenated products thereof can also be used.

Other examples include polyethylene terephthalate,
The distillation residue, the polymer itself, or the waste of its molded product, which is a by-product in the process of manufacturing alkylene phthalate polymers such as polybutylene terephthalate, is mixed with the following polyhydric alcohol for crosslinking agent and 200 to 280
Aromatic polyester polyol compositions obtained by heating to .degree. C. and transesterification are also highly preferred raw materials for the present invention.

The polyols may be used alone or in a mixture of two or more, and the hydroxyl value of the polyol or the mixture thereof is preferably 10 to 380 mgKOH/g, and preferably 20 to 380 mgKOH/g.
180 mg KOH/g is particularly preferred. In order to increase reactivity, it is desirable that the hydroxyl groups of the polymer polyol with a hydroxyl value of 100 mgKOH/g or less contain 50% or more of primary hydroxyl groups. Therefore, it is preferable that the polyether polyol obtained by addition polymerizing propylene oxide or butylene oxide to another alcohol has its terminal end capped with ethylene oxide.

Further, it is desirable that the low molecular weight polyol used for producing the polyester polyol has a primary hydroxyl group at the end.

As a crosslinking material, ethylenediamine, hexamethylenediamine, p-phenylenediamine, 3,
3'-dichloro-4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,5,3',5'-tetramethyl-
Polyamines such as 4,4'-diaminodiphenylmethane, 3,5-diethyl-3',5'-diisopropyldiaminodiphenylmethane, 3,5,3',5'-tetraisopropyldiaminodiphenylmethane,
Ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol,
Polyhydric alcohols such as butanediol, hexanediol, glycerin, trimethylolpropane, diethanolamine, triethanolamine, phenyldiethanolamine, N-(2-hydroxyethoxyethyl)-N-(2-hydroxyethyl)aniline, N, N-di(2-hydroxyethoxyethyl)aniline, tripropanolamine, phenyldipropanolamine, N,N-
Alkanolamines such as di(2-hydroxypropoxypropyl)aniline are used alone or in combination.

The amount of organic polyisocyanate, polyol and crosslinking agent used is
The equivalent ratio (NCO/H) between the NCO group and the active hydrogen in the polyol and crosslinking agent is adjusted to be 0.90 to 1.30.

The catalyst used in the present invention includes tertiary amines such as N-methylmorpholine, triethylamine, triethylenediamine, N,N,N',N'-tetramethylpropanediamine, and bis(2-dimethylaminoethyl)ether. , and lead octoate,
Organometallic compounds such as lead naphthenate, tin octoate, and dibutyltin dilaurate are used alone or in combination. The amount used is based on the total amount of raw materials used.
0.001 to 5% by weight is preferred.

Other auxiliaries that can be used in the present invention include plasticizers, fillers,
Stabilizers, colorants, etc.

Examples of plasticizers include dioctyl phthalate (DOP), dibutyl phthalate (DBP), dioctyl adipate (DOA), tricresyl phosphate (TCP), and chlorinated paraffin. Examples of fillers include glass fiber, Carbon black, calcium carbonate, talc, kaolin,
These include zeolite, diatomaceous earth, perlite, vermiculite, and titanium dioxide.

Examples of stabilizers include trade names Irganox 1010 and 1076 (manufactured by Ciba Geigy), Yoshinox BHT, BB, and GSY-930 (manufactured by Yoshitomi Pharmaceutical Co., Ltd.).
Positionally hindered phenols such as tinuvin p,
Benzotriazoles such as 327 and 328 (manufactured by Ciba Geigy); benzophenones such as Tomisorp 800 (manufactured by Yoshitomi Pharmaceutical); Sanol LS-770 and 744;
Positionally hindered amines such as Tinuvin 144 (manufactured by Ciba Geigy) are used.

In applying the present invention, either the one-shot method or the prepolymer method can be used. When carrying out the one-shot method, the organic polyisocyanate is used as it is, or an appropriate amount of plasticizer is mixed to adjust the flow rate ratio of the components, and a polyol, a crosslinking agent, a catalyst, a coloring agent, etc. are mixed as component A. This is called the B component. Both components A and B are ejected from a high-pressure spray device at a predetermined flow rate ratio and sprayed onto the foam molded product. If glass fiber is used at this time, the long glass fiber is cut into a certain length at the head of the gun and blown with air, and mixed with both components A and B while flying through the air. The mixture of both components A and B that adheres to the molded article hardens in about ten seconds. This operation is repeated several times as necessary to form a protective layer of a predetermined length.

When the prepolymer method is used, a prepolymer obtained by reacting an organic polyisocyanate and a part of a polyol or a polyhydric alcohol crosslinking agent at 70 to 80° C. for several hours in a nitrogen stream is used as liquid A. Examples will be described below. In the present invention, parts refer to parts by weight.

Example 1 80 parts of carbodiimide-modified liquid MDI having an NCO group content of 28.5% by weight and 20 parts of DOP were mixed in a nitrogen stream to obtain component A. The NCO content of this liquid A was 22.8% by weight.

Separately, 79 parts of a polyether polyol with a hydroxyl value of 56 mgKOH/g and a primary hydroxyl group content of 55% by weight obtained by addition polymerization of propylene oxide and ethylene oxide to glycerin, 11 parts of ethylene glycol as a crosslinking agent, and N,N- Component B was prepared by mixing 9 parts of di(2-hydroxypropoxypropyl)aniline and 1.0 part of dibutyltin dilaurate as a catalyst.

Next, pre-expanded polystyrene beads were placed in a helmet mold and heated to form a foam molded product with a thickness of 20 mm.

Using Probler T-3A type high pressure spray equipment,
Both components A and B were discharged to the outside of the above helmet-shaped foam molding at a pressure of 190 kg/cm ² and a flow rate ratio (volume) of 1:1.
I spray painted it 3-4 times. After leaving it for one hour, a strong polyurethane elastomer layer approximately 2 mm thick was formed on the surface of the helmet. The NCO/H (equivalent ratio) of the mixture of both components A and B was 1.05.

When the surface of this helmet was struck with a hammer, the hammer was bounced back and the helmet remained undamaged. On the other hand, the unpainted foamed molded product was easily damaged by the same operation.

Example 2 Hydroxyl value 55 mgKOH/g, primary hydroxyl group content obtained by addition polymerizing propylene oxide and ethylene oxide to glycerin
55 parts of a 90% by weight polyether polyol, 20 parts of a polyether polyol with a hydroxyl value of 280 mg KOH/g obtained by addition polymerizing propylene oxide to ethylene glycol, 10 parts of an ethylene glycol crosslinker, 0.8 parts of a dibutyltin dilaurate catalyst,
14.2 parts of colorant was mixed to obtain component B.

Separately, 70 parts of modified MDI (manufactured by Mitsui Nisso Urethane Co., Ltd.: MDI-LK) with an NCO group content of 28.5%, 15 parts of MDI (manufactured by Mitsui Nisso Urethane Co., Ltd.: MDI-PH), 5 parts of dipropylene glycol crosslinking agent, A prepolymer obtained by mixing 10 parts of DOP and reacting at 70° C. for 3.5 hours in a nitrogen stream was used as component A. The NCO content of component A was 21% by weight.

Next, polystyrene foam beads were placed in a mold and heated to form a transport box.

Both components A and B were spray-coated on both the inside and outside surfaces of the transport box under the same conditions as in Example 1. At this time, the NCO/H (equivalent ratio) of the mixture of both components A and B was 1.05.

This painted transport box was filled with fish and crushed ice and repeatedly transported over long distances, but no damage or scratches were observed on either the inside or outside of the transport box. On the other hand, the unpainted transport box had numerous dents and scratches on both the inside and outside surfaces.

Example 3 4 equipped with stirrer, thermometer and reflux condenser
1,000 parts of polyethylene terephthalate chips and 1,000 parts of diethylene glycol were placed in a two-necked flask, and the mixture was gradually heated to 240°C while stirring.
The polyethylene terephthalate melted and the mixture of ethylene glycol and diethylene glycol refluxed. After continuing the reaction for 7 hours while maintaining the same temperature, it was cooled to room temperature and discharged. The resulting polyester polyol composition has a hydroxyl value of 370 mg.
It was KOH/g. 0.6 dibutyltin dilaurate as a catalyst to 100 parts of this polyester polyol
% was added to obtain component B.

Apart from crude MDI95.4 with NCO group content 30.5% by weight
1 part and 5.2 parts of DBP were mixed in a nitrogen stream to obtain component A.

Next, thick plates having predetermined dimensions were cut out from the foamed phenolic resin block using a saw, and the plates were assembled using adhesive to form a transportation box.

Both A and B components are discharged onto the inner surface of this transport box.
It was sprayed several times at a flow rate of 190 kg/cm ² and a flow rate (volume) of 1:1 to form a film approximately 1.5 mm thick. At this time, A,
The HCO/H (equivalent ratio) in the mixture of both components B was 1.05.

Fish were packed in this painted transport box and transported over long distances, but no changes were observed in the fish. On the other hand, when an unpainted transport box was used, minute fragments of foamed phenolic resin were generated due to friction with the fish bodies due to vibrations during transportation, contaminating the fish bodies.

Comparative Example 1 Spraying was performed using a heat-curing urethane resin. The isocyanate component of liquid A is Hypren L.
-100 (prepolymer manufactured by Mitsui Toatsu Chemical Co., Ltd.
NCO% = 4.2, viscosity = 22000cp/25℃) was used, but the viscosity was high and it could not be sprayed as it was, so ethyl acetate (362 parts) was added to L-100 (638 parts).
Adjusted by adding. As a curing agent for liquid B, 4,4'-diamino-3,3'-dichlorodiphenylmethane (125 parts) was dissolved in mesityl oxide (875 parts). The blending ratio of both is A liquid/B liquid =
100/64 parts (NCO/H equivalent ratio of both components A and B is
1.05), and the molding machine is Binks Model G.
Attach a 43P gun to the mold and increase the liquid pressure to 20Kg/at room temperature.
It was sprayed onto the surface of a fish box made of expanded polystyrene at cm ² conditions. As a result, the foamed polystyrene was dissolved by the solvent contained therein, making it impossible to form a film on the surface.

Separately, in order to obtain a coating film, a sheet was created by laminating it on a polypropylene board (non-foamed material), but in order to volatilize the solvent, it was dried to a thickness of 0.25 mm for 25 minutes (at room temperature) and gelled. It was necessary to repeat the process 5 times while checking the conditions, and then to cure at 100°C for 3 hours, which was a very complicated process.

Claims (1)

[Claims] 1. Spraying the following cold-curing highly reactive polyurethane stock solution onto the outer surface of the foamed synthetic resin molding onto the surface of the protector using a high-pressure spraying device at a discharge pressure of 30 to 210 kg/cm ² . A method for strengthening a foam protector characterized by: (A) A base material containing one or a mixture of two or more selected from the group of diphenylmethane diisocyanate, polymethylene polyphenyl polyisocyanate, or modified products thereof; (B) 50% primary hydroxyl group; a curing agent with a hydroxyl value of 10 to 380 mgKOH/g, which contains 50% or more of a polymer polyol with a hydroxyl value of 100 mgKOH/g or less; (C) aliphatic or aromatic polyamines; a crosslinking agent containing one or a mixture of two or more selected from the group of alcohols or alkanolamines; (D) tertiary amines or organometallic compounds alone or in a mixture of two or more; The catalysts A to D have an equivalent ratio (NCO/H) of the isocyanate group of the organic polyisocyanate to the active hydrogen in the polyol and crosslinking agent of 0.9 to 1.30,
The catalyst is 0.001 to 0.001 to the total amount of raw materials (A to C)
Room temperature curing highly reactive polyurethane stock solution containing 5% by weight.