JPH01317720A - Production of molded product - Google Patents

Abstract

PURPOSE:To enhance water resistance, cracking resistance, appearance and transparency by applying a composition, which is prepared by mixing a specific radical curable polymer with a photopolymerization initiator and org. peroxide as a photo-setting resin and contains no org. acid salt of cobalt, to a mold as gel coat and irradiating the gel coat layer with light to cure the same while injecting a specific monomer solution to cure the gel coat layer and the injection layer under heating. CONSTITUTION:A radical curable polymer having an MW of 5,000 or more and having one or more (meth)acryloyl group in the side chain thereof is mixed with a photopolymerization initiator and org. peroxide as a photosetting resin to prepare a composition containing no org. acid salt of cobalt and this composition is applied to a mold as gel coat and irradiated with light to cure the gel coat to a desired curing degree. A monomer solution of a radical curable polymer having an MW of 5,000 or more and having one or more (meth)acryloyl group in the side chain thereof is injected, and the gel coat layer and the injection molded layer are cured under heating to prepare a molded product excellent in water resistance, cracking resistance, appearance and transparency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention mainly relates to the production of molded products that require aesthetic appeal, such as bathtubs, table tops, washstands, and the like.

[Conventional technology and issues]

Radical-curable resins, such as polyester resins and vinyl ester resins, can be cured by heating, but if this is attempted on an industrial scale, large heating equipment is required and costs are high, so they must be cured at the lowest possible temperature. If possible, a method of curing at room temperature is required. However, in order to cure these curable resins at or near room temperature, an organic peroxide such as ketone peroxide is used as a curing agent, and an organic acid salt of cobalt (naphthenate, naphthenate, etc.) is used as a curing accelerator. octylate) must be used in combination.

However, when cobalt naphthenate is used, for example, it has the undesirable drawback that molded products and coatings yellow over time.

For example, when it comes to artificial marble, which is required to have an extremely light color, discoloration during use is not desirable because it greatly reduces its commercial value. Therefore, discoloration of this layer must be avoided.

However, although the use of cobalt salts is undesirable in terms of yellowing of the resin,
Until now, effective room temperature or low temperature curing of resins has not been possible without this.

Furthermore, the water resistance of the gel coat layer is not necessarily sufficient with conventional resins, and the crack resistance of the cast part and the transparent appearance are still insufficient.

[Means and effects for solving the problem] The present inventors have made numerous attempts to avoid the use of cobalt salts, and have found that in order to prevent coloring during curing at room temperature, it is necessary to accelerate the curing of peroxide-based curing agents. We found that it is optimal to use a photocuring method without using an organic acid salt of cobalt as a cobalt agent, leading to the present invention.

Although the photocuring method was very effective in curing gel coats, other drawbacks were also discovered. When it is fully photocured to exhibit sufficient physical properties as a gel coat, the following F
Peeling was likely to occur between the RP laminate or the cast layer. This drawback can be prevented by polishing the gel coat to improve its adhesion, but this significantly increases the number of man-hours and is disadvantageous in terms of productivity.

Therefore, in order to avoid this drawback, instead of completely curing with light curing, light curing is used to advance the curing to an intermediate curing stage, and the final complete curing (curing)
found that their objective could be achieved by using organic peroxides.

Since we used a radically curable polymer with a molecular weight of 5000 or more and one or more (meth)acroyl groups in the side chain for the gel coat layer in (1) and the casting layer in summer 1),
The water resistance of the gel coat layer and the crack resistance of the cast layer,
The appearance transparency has also been improved.

Since the curing by light in step (I) of the present invention can be easily controlled, the curing of the gel coat or the subsequent laminated portion can be adjusted to the required degree.

After the gel coat layer or, if necessary, the laminated portion has been light-cured, casting is performed using a radical curing resin containing a radical curing agent, and this is heated and cured together with the gel coat layer. As a result, the casting part and the gel coat part are cured and bonded together, and a strong molded product without peeling can be obtained. The heating temperature for curing is 100°C or less, preferably about 70 to 80°C.

The gel coat uses a radical curing resin that can be photocured and cured with organic peroxide. In particular, in the present invention, a monomer solution of a radically curable polymer having one or more (meth)acryloyl groups in the polymer side chain having a molecular weight of 5,000 or more is suitable. By selecting this polymer, the water resistance of the gel coat layer can be improved.

This unsaturated polymer having a (meth)acryloyl group in its side chain (hereinafter simply referred to as unsaturated polymer) is synthesized by the following method.

(i) A polymer having a hydroxyl group in its side chain is reacted with an unsaturated isocyanate having a methacryloyl group.

(ii> Reacting a polymer having an epoxy group in a side chain with (meth)acrylic acid; (iii) Reacting a polymer having an acid anhydride group in a side chain with an unsaturated alcohol having a (meth)acryloyl group.

This is shown in the formula below.

(a) Urethane type unsaturated polymer (b) Vinyl ester type lower saturated polymer Side chain epoxy group polymer Methacrylic acid vinyl ester type unsaturated polymer (c) Ester type unsaturated polymer Ester type unsaturated polymer Serves as raw material for unsaturated polymer Each polymer is synthesized by polymerization of monomers, but for urethane-type unsaturated polymers, side-chain hydroxyl polymers such as cellulose derivatives can also be used, but polymerization of nil monomers is preferable in terms of cost and boiling resistance. Existing methods can be used for hexapolymerization, but the direct polymerization method is convenient when considering the handling of subsequent steps.

These casting unsaturated polymers are used as a mixture with a monomer solution, for example styrene monomer. The mixing ratio is 30 to 70%, preferably 40 to 60% in terms of concentration of unsaturated polymer.

The above unsaturated polymers are used for the gel coat in step (1) and the casting layer in step (II). Further, polyester resins and vinyl ester resins can also be used in combination if necessary.

In order to make these radically curable unsaturated polymers photocurable as the gel coat resin of the present invention, it is necessary to use a photopolymerization initiator together. Various types of photopolymerization initiators can be used, but from the perspective of avoiding coloring of the cured gel coat layer, hydrogen abstraction types that use amines in combination are not suitable, and cleavage type radical generators are preferable. .

Examples of these include (a) acetophenone derivatives, such as 2-hydroxy-2-methyl-1-phenylpropan-1-one (Merck & Co., Ltd. "Daroeure #1173"); (b) benzyl ketals, such as hydroxy- Cyclohexyl-phenylketone (Ciba “Irgaeure #184”)
can be given.

The gel coat resin of the present invention uses an organic peroxide in combination for final complete curing. The type of organic peroxide used for this is not particularly specified, but in reality, the operation to form a cast layer is often carried out at 100°C or lower, so the temperature is relatively low, e.g. A type that decomposes at 80°C or lower is desirable.

As an example, to obtain a half-life of 10 hours, the decomposition temperature is 1
Examples include ketone peroxide, peroxyketal, peroxycarbonate, diacyl peroxide, and peroxyester at a temperature of 20°C or less. Among them, peroxycarbonate and peroxyester are advantageous, and the curing temperature is appropriate. Considering handling safety, bis(t-butylcyclohexyl) peroxydicarbonate (Kayaku Nury Co., Ltd. "Perkadox #16")
) is appropriate. Combination use with other peroxides is also possible.

When casting and curing the resin, a filler is usually used in combination with the casting resin to provide a suitable degree of transparency and to prevent cracks caused by heat generation during curing and molding.

Glass powder, aluminum hydroxide, etc. are commonly used as fillers. Furthermore, in the composition and method of the present invention, it is of course possible to use a coloring agent, a mold release agent, a thixotropy imparting agent, a thermoplastic polymer, etc. in combination, if necessary.

Next, in order to further explain the present invention, Examples are shown below.

Example 1 (Synthesis of gel coat resin (A) (urethane type unsaturated polymer A)) 936 g of styrene, 2-
Hydroxyethyl methacrylate (HEMA) 130g
When the sample was weighed and heated at 120° C. for 6 hours in a nitrogen stream, the reaction rate reached about 42%, and as a result of gas chromatography analysis, it was determined that the amount of free HEMA was about 14% of the initially charged amount.

Add 0.2 g of hydroquinone, lower the temperature to 70°C, and switch to air flow.
140. , dibutyltin dilaurate (3 g) was added and reacted at 70° C. for 5 hours, and as a result of infrared analysis, it was confirmed that free isocyanate had disappeared.

A urethane-type unsaturated polymer (A) having a Hazen color number of 30 and a viscosity of 11.4 poise was obtained.

(Production of casting resin (B) (vinyl ester type unsaturated polymer B)) 936 g of styrene and 142 g of glycidyl methacrylate were charged into a 21 separable flask equipped with a stirrer, a reflux condenser, a thermometer, and a gas introduction tube. In nitrogen stream 1
When heated at 20-122°C for 6 hours, the polymer becomes approximately 43
%, and the residual ratio of glycidyl methacrylate to the charged amount was about 16%.

To this, 0.3 g of hydroquinone, 95 g of methacrylic acid,
5 g of trimethylbenzylammonium chloride was added, the temperature was lowered to 100-105° C., and the reaction was carried out for 12 hours in an air stream.

As a result of infrared analysis, it was determined that the absorption of epoxy groups had disappeared.

Add to this 130g of ethylene glycol dimethacrylate
In addition, a casting resin (B) having a Hazen color number of 100 and a viscosity of 14.1 poise was obtained.

(Formation of gel coat layer) 100 parts of unsaturated polymer (A), 10 parts of ethylene glycol dimethacrylate, 3 parts of Elozilt 200,
Silane coupling agent (Shin-Etsu Chemical Co., Ltd. KBM-503)
) and 0.5 part of Merck & Co., Ltd. “Dar” as a photoinitiator.
oeure #1173” and 1 part of an organic peroxide (Kayaku Noury Co., Ltd. “Barriki Dox #16”) were added.
A photocurable gel coat composition (a) was obtained by roll kneading.

As a comparative example, a gel coat composition (b) was prepared by adding 0.1 part of cobalt naphthenate (6% Co) to 100 parts of the unsaturated polymer (A).

On a 30ciX 30ciX 5gg glass plate coated with a mold release agent, apply gel coat to a thickness of 0.5gm using a bar coater, wait until the coated surface is uniform, and apply a 250W sun lamp ( When the gel coat layer was irradiated for about 15 minutes at a distance of 30 cm below (manufactured by Stanley Electric Co., Ltd.), the gel coat layer was hardened to the extent that it was dry to the touch.

(Casting, heating, and curing) The cured gel coat layer is on one side, and a separate layer with a thickness of 2 mg is
FRP using glass mat colored white was placed, and the interval between them was set to 10% g. During this time, 100 parts of casting resin (B), 200 parts of Nippon Ferro Frit B-10, and Nippon Oil & Fats Co., Ltd. ) 1.5 parts of Perbutyl PV was mixed therewith, and after defoaming casting, the mixture was closed at 70°C for 2 hours and cured at 80°C for 2 hours.

A molded product using the gel coat composition (a) is a molded product (
a), a molded product using the gel coat composition (b) was used as molded product (b) 6 Both molded products were cut at 15 ci x 15 cm, and a diameter of 10 cm was obtained.
The gel coat layer was placed on the inside of a boiling test container with 4 circular holes on one side, and the temperature was 98°C.
Boiling tests were conducted at ~99°C. The results are shown in Table 1.
As can be seen from this table, the present invention, which does not use cobalt naphthenate, showed extremely excellent performance.

Table 1 Example 2 The vinyl ester resin type unsaturated polymer (B) used for casting in Example 1 was used for gel coat. Polymer (B) 1
00 parts, Ecosil 3 parts, coupling agent 0.5 parts, Ciba's "Irgaeure #181" as a photopolymerization initiator
2 parts of barbutyl pv and 1 part of barbutyl pv were kneaded to obtain a gel coat composition (e).

(Synthesis of casting resin (C) (ester-type unsaturated polymer)) 936 g of styrene was charged into a 21 separable flask equipped with a stirrer, a heating dropping funnel, a reflux condenser, and a thermometer with a gas introduction tube, and the temperature After dropping 98 g of molten maleic anhydride at 120°C over 3 hours, an additional 1.5
Keep at the same temperature for the time.

Next, 200 g of 2-hydroxyethyl methacrylate
, diptyltin dioxide 5g, hydroquinone 0.1
g and reacted at 85 to 90°C for 22 hours. A casting resin (C) having a Hazen color number of 50 and a viscosity of 5.9 voids was obtained. As a result of infrared analysis, it was determined that about 80% of the acid anhydride groups were ring-opened.

(Formation, casting, heating, and curing of gel coat layer) After applying and photocuring the gel coat composition (e) under the same conditions as in Example 1, a #360 silane-treated glass mat was further placed, and the gel coat composition After impregnating and defoaming material (c), it was photocured in the same manner.

FRP colored white is used as a backing layer, and 100 parts of casting resin (C), 180 parts of frit, and 2 parts of Percure 0 (t-butylperoxy-2=ethylhexanate) manufactured by NOF Corporation are kneaded. The molded product was cast to a thickness of 1 Qiu+, initially cured at 80° C. for 2 hours, and then demolded.

This was cut and a boiling resistance test was conducted in the same manner as in Example 1. Even after the 1000 hour boiling test, no abnormality was observed in the appearance of the surface gel coat layer.

Claims (1)

[Scope of Claims] (I) (1) Photocurable resin (a) Radically curable polymer having one or more (meth)acryloyl groups in the side chain with a molecular weight of 5,000 or more (b) Photopolymerization initiator (c) A composition mixed with an organic peroxide and containing substantially no organic acid salt of cobalt is applied to a mold as a gel coat, and the gel coat is cured to a desired degree of hardening by irradiating it with light. (II) casting a monomer solution of a radically curable polymer having one or more (meth)acryloyl groups in the side chain with a molecular weight of 5000 or more with or without backing with glass fiber; A method for producing a molded article, which comprises heating and curing a gel coat layer and a casting layer.