JPS5914491B2 - Molding method for reinforced plastics - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a molding method that can easily and inexpensively provide a phenolic resin molded product with excellent flame retardant properties, mechanical strength, etc.

Conventionally, reinforced plastics using phenolic resin were
There are two methods: a compound method and a lamination method, depending on the form of the molding material used for molding.

These methods require complicated steps from material production to completion of molding, and each method also has the drawbacks of lack of freedom in molded product shape and mechanical strength. For example, in the case of the compound method, there are two ways to manufacture the molding material. One is a liquid type resin such as resol type resin and a solvent such as water or alcohol added as necessary, a lubricant, and coloring. The mixture is mixed with 10 base materials such as wood flour, pulp, and cloth in a kneader or blender, and the base materials impregnated with these compounds must undergo a drying process to remove the solvent, and if necessary, B-stage. Then compound. Another method is to mix a solid resin such as a novolac type phenolic resin with a curing agent, a lubricant, a coloring agent, wood flour, etc. using a blender, panburi mixer, etc., and then mix this using a roll, co-kneader, etc. The mixture is heated and kneaded to adjust the flow characteristics to the desired state, then cooled and crushed into a granular or powdered compound using a pulverizer. The above is the method of manufacturing the compound,
The process is extremely complicated, such as drying, B-staging, kneading, and pulverization, and when selecting the base material, it is necessary to improve the uniformity of the compound, improve the impregnability of the base material, and avoid damage to the base material. For reasons such as the ease of adjusting flow characteristics, it is necessary to use only wood flour and pulp, and to use materials with as fine a shape as possible. The obtained compound is molded by transfer molding or injection molding, and the processing principles at this time are usually 1) heating the compound to give it fluidity of 30° plasticization, 2. Fill a mold with a flowable compound and give it a predetermined shape. 3. Once the predetermined shape is given, it is further heated to advance the curing reaction, and after completion, it is cooled and removed. Out a hardening'
It goes through three stages. When the compound is subjected to 35 molding, it is necessary to change the mold temperature by several steps starting from preheating, and the molding pressure is also very high. In order to obtain a better molded product, a degassing step is essential, and when a compound is used in this way, the number of processing steps is extremely large. In addition, the resulting molded product also has the disadvantage of poor mechanical strength because the base material used is limited to fine wood, pulp, etc. due to the problems in compound production and flow problems during molding processing. . ,3
On the other hand, in the case of the lamination method, the manufacturing method of laminated materials generally uses a resol type phenolic resin in which the resin is dissolved in a solvent such as water or alcohol, and this resin liquid is mixed with continuous paper, cloth, other organic fibers, glass, etc. The process of impregnating the base material with resin liquid by passing it through a base material such as fibers, then adjusting the amount of resin with a roll, ironing bar, etc., and then removing the volatile content by heating (drying process) After that, it is made into a prepreg-like laminated material.

In the forming process, an appropriate number of sheets of the laminated material are stacked to have a predetermined thickness, and a laminated plate is formed by heating and pressing for 50 to 180 minutes. That is, similar to the compounding method, pre-processes such as impregnating the base material with resin and drying are necessary.
Particularly in the drying process, solvent scattering occurs as a secondary problem. Furthermore, there are problems in the setting of materials, molding time, etc. in the molding process, and in particular, in order to obtain laminated molded products with large and complex shapes, it is necessary to preform after cutting into various shapes and then heat and pressure molding. Furthermore, molded products obtained by such lamination methods are prone to breakage of the base material, pinholes, etc.
There are drawbacks such as a high content of the base material, and the product price has to be high. The present inventors have improved the drawbacks of conventional methods of plastic molding using phenolic resins, and obtained an inexpensive reinforced plastic that can be easily molded into large, complex-shaped molded products and has excellent mechanical strength. As a result of careful study, we found that the water content was 5 to 50% by weight (resin solid content) by adding and stirring a resol type phenolic resin, a curing agent, and if necessary, a filler, a mold release agent, a coloring agent, etc. Reinforced plastic made by directly impregnating 10 to 70% by weight of an inorganic fiber reinforcing material (in the molded product) with syrup or paste (based on the total weight of The inventors have discovered that unexpected effects can be obtained using the steel molding method, and have completed the present invention.

According to the method of the present invention, there is no forced drying process seen in conventional phenolic resin molding methods, and the molding processes such as crushing, preheating, preforming, degassing, etc. are dramatically simplified. It can be molded by a simple method, and by adding water to the compound, it improves impregnability and fluidity, and the molded product after curing exhibits unexpectedly low smoke generation. By doing so, the molding cycle is shortened.
This provides advantages such as the possibility of using long fiber reinforcing materials.

The resol type phenolic resin used in the present invention refers to one or more phenols such as phenol, resorcinol, xylenol, hydroquinone, bisphenol A1, butylphenol, octylphenol, etc., and aldehydes such as formaldehyde in the presence of an alkaline catalyst. The resin is reacted under normal manufacturing conditions, and is usually a liquid resin containing water.

The raw material composition of such resol type phenolic resins has a relatively wide range, but when an acid is used as a curing agent, the molar ratio of aldehydes/phenols (F/P) is 0.5 to 3.0. Preferably it is in the range of 0.8 to 2.5.

When F/P is less than 0.5, curability is poor, resulting in poor curing and blistering, as well as a decrease in mechanical strength due to a decrease in crosslinking density, and an increase in free phenol, resulting in poor flame retardancy. Deterioration of properties and odor problems during molding also occur. On the other hand, if F/P is greater than 3.0, the amount of free formaldehyde will increase, resulting in decreased flame retardant properties, odor problems during molding, and poor resin stability. F/P is 1.
Mechanical strength and flame retardant properties are highest near 5. or,
A phenolic resin modified by replacing part or all of the raw material phenol with a highly reactive raw material such as resorcinol.
In the case of a type in which aldehydes are mainly used as a curing agent, F/P is in the range of 0.4 to 0.8.

When a modified raw material such as resorcinol is added, curability, mechanical strength, and flame retardant properties are improved. The pH of the resol type phenolic resin used in the present invention is preferably in the range of 3 to 12 as long as the stability of the resin is not affected, and molding operations are facilitated within this range.

The curing agent is one commonly used for resol-type phenolic resins, and is a single organic or inorganic acid such as benzenesulfonic acid, para-toluenesulfonic acid, xylene sulfonic acid, phenolsulfonic acid, sulfuric acid, or phosphoric acid. Alternatively, aldehydes such as diformaldehyde, paraformaldehyde, and furfural may be used in combination.

When aldehydes are used as curing agents, the above-mentioned acids or alkalis such as sodium hydroxide and potassium hydroxide may be used in combination. The amount of curing agent added is resin solid content 100
0.5 to 20 parts by weight, preferably 1 to 1 parts by weight
5 parts by weight. The type and amount of the curing agent can be appropriately selected depending on the raw material composition of the phenolic resin, reaction conditions, pH, etc., but if the amount used is less than 0.5 parts by weight, the curing time will be long and the moldability will be poor. If it exceeds 20 parts by weight, the pot life of the compound will be shortened and the viscosity will increase rapidly, making it impossible for the compound to reach the ends of the reinforcing material (poor impregnation).
It may also cause the compound to wash away the reinforcing material that has been set (washing). In the present invention, in addition to a resol type phenolic resin and a curing agent, if necessary, fillers such as hydrated alumina, clay, and talc, mold release agents such as metal soaps, phosphates, and waxes, and inorganic pigments are used. , coloring agents such as organic pigments may also be added as needed.

The water contained in the formulation of the present invention includes not only the water originally contained in the resol type phenolic resin but also water added together with the curing agent, and the proportion (water content) is determined by the amount of water added to the solid resin in the formulation. 5-50% by weight based on the total weight of water and water
, preferably 15 to 35% by weight. If the moisture content exceeds 50% by weight, curing during molding will be delayed, and since the resin solid content will be low, it will not be possible to obtain a good molded product that is integrated with the fiber reinforcement, and the surface gloss and mechanical properties will deteriorate. Strength also decreases.

Furthermore, if the water content is less than 5% by weight, not only will it be difficult to stir the resin compound, but the impregnation of the compound into the fiber reinforcing material or the subsequent defoaming properties will be poor, resulting in a reduction in work efficiency. , causing a decrease in the strength of the molded product. Particularly in heat/pressure molding such as preform matched die molding, this may cause poor impregnation or washing of the reinforcing material set in the mold. Regarding flame retardant properties, when the residual water content is small, flame retardancy and smoke resistance decrease. In the present invention, in addition to the above-mentioned water, alcohols such as methanol can also be used as solvents contained in the formulation as long as they are about 1/5 or less of the amount of water. Since problems such as deterioration of properties and blistering of molded plastics are likely to occur, it is preferable to use only water.

Inorganic fiber reinforcing materials used in the method of the present invention include glass fibers such as chopped strand mat, glass chop, glass cloth, glass roping, continuous mat, preform mat, surf ace mat, carbon fiber, asbestos, Inorganic fibers such as whiskers can be used as appropriate.

In the case of glass fiber, its composition may be any of alkali-free glass, alkali-containing glass, and chemical glass. Furthermore, glass fibers that have been subjected to a known treatment, such as silane treatment, can be used, and have excellent impregnating properties, curing properties, and adhesion properties with resins, and also improve strength. The content of the inorganic fiber reinforcing material in the molded product is 10 to 70% by weight, preferably 25 to 50% by weight.
Weight%.

If the content of the inorganic fiber reinforcing material is less than 10% by weight, sufficient strength will not be obtained and the flame retardancy will also decrease. If it exceeds 70% by weight, it is difficult to impregnate the resin.

In the reinforced plastic molding method of the present invention, an inorganic fiber reinforcing material is impregnated with a water-containing compound and cured without forced drying. Depending on the method, room temperature ~1
The temperature is 80°C.

Examples of molding methods include pan lay-up method, spray-up method, preform mated die method, cold breath method, resin injection method, vacuum (pressure)
Molding methods such as the buck method, pultrusion method, BMC method, SMC method, and filament winding method can be used. Below, some molding methods will be explained. For example, in the case of the pan lay-up method and the spray-up method, the reinforcing material may be impregnated with the compound on the mold, and after defoaming, it may be cured at room temperature. After-curing is preferably carried out at 50 to 120° C. to ensure sufficient crosslinking. In these general lamination methods, when a film or the like is brought into close contact with the laminated surface and cured, moisture evaporation is prevented, the surface is finished neatly, and the product has better flame retardant properties. Also,
In heat/pressure molding methods such as the preform mated die method, molding is performed at a mold temperature of 50 to 180°C, but in these molding methods, the male and female molds have a narrow X and clearance during press molding. They fit together with appropriate sliding parts (travel), and the resin gels quickly in several tens of seconds. However, the resin in the clearance area hardens faster than the molded part, and the material inside the mold (molded part) Because it hardens in a confined state, the volatile matter in the material inside the mold hardly evaporates. That is,
Most of the contained water remains in the molded product, resulting in a molded product with good flame retardancy. The molded article obtained by the method of the present invention is
Fields that require mechanical strength and flame retardancy, such as ducts,
Used for scrubbers, interior wall materials, etc. The present invention will be explained below with reference to examples, in which parts and % represent parts by weight and % by weight.

Example 1 and Comparative Examples 1 and 2 are for comparison of the process (time) and moldability between the molding method according to the present invention and the conventional molding method.

Example 1 Resol type phenolic resin ([Plyoven TD2
3O7 (manufactured by Dainippon Ink Chemical Co., Ltd.) adjusted to a moisture content of 30%, 7 parts of phenolsulfonic acid, 30 parts of clay, and 1 part of zinc stearate were used to prepare a box-shaped product [
Mold: 30CTfL (horizontal) x 20? (Vertical) x 20?
(Fukasa)] was molded by mated die molding (MMD molding), and the time required from measuring the raw materials to completing molding was 25 minutes.

In addition, the obtained molded product with a glass fiber content of 30% was free from poor impregnation, pinholes, and blisters, had a smooth surface, and was excellent in gloss, had a bending strength of 17.5 kg/Md, and an oxygen index (JISK-7201). ) It was 62.

Comparative Example 1 Water was dehydrated from the resol type phenolic resin used in Example 1, and methanol was added thereto to prepare a resol type phenolic resin containing 30% methanol.

When molding was performed using a mold similar to that in Example 1 using a molding material manufactured by a conventionally known "layering method", the required time was 152 minutes.

When the pressing time was shorter than 120 minutes, curing was not sufficient.

The glass fiber content of the obtained molded product was 60%, and it was a defective product with hissoholes, unevenness on the surface, and fiber breakage at the corners. Comparative Example 2 In order to compare with the case using the conventionally known "compound method", a novolak type phenolic resin ("Barcam 13") was used.
64'' manufactured by Dainippon Ink & Chemicals Co., Ltd.) 67 parts, 6 mm
A box-like product similar to that in Example 1 was molded using 30 parts of glass chops, 1 part of magnesium oxide, 2 parts of magnesium stearate, and 10 parts of hexamethylenetetramine, and the required time was 137 minutes.

The resulting molded product developed blisters unless gas was vented during molding.

Further, the strength of the molded product varied depending on the orientation of the glass fibers, and the bending strength was 4 to 11 kg/Md, which was a lower value compared to Example 1.

Comparative Example 3 A molded product was obtained in Example 1 except that the amount of glass fiber was 8%.

The obtained molded product had a low bending strength of 3.5k9/Md, was brittle, partially blistered, and had an oxygen index (flame retardance, JIS
-K-7201) was 42. Example 2 Resol type phenolic resin [Plyoven J-30
3'' (manufactured by Dainippon Ink & Chemicals Co., Ltd.) was dehydrated and adjusted to have a moisture content of 25%.

Adjusted resin with moisture content of 25% (resin solid content 75%)
65% aqueous phenolsulfonic acid solution per 100 parts 7
1 part was added and stirred to obtain a blend with a viscosity of 5 poise. Continuous mat (4507/
Three sheets (m") were stacked and set, and the above-mentioned compound 8207 was poured over them and pressed under molding conditions of a pressure of 30k9/C77i and a temperature of 125°C for 10 minutes.

The resulting molded product with a thickness of 3 mTn was free from poor impregnation, blisters, floating fibers, and pinholes, and had a smooth surface and good gloss. Furthermore, almost the same strength and flame retardance results were obtained by molding at 150°C for 10 minutes.

Example 3 Resol type phenolic resin [Plyoven TD-2
307'' (manufactured by Dainippon Ink & Chemicals Co., Ltd.) was adjusted by adding water so that the moisture content was 30%, and the following formulation yielded a 30 poise formulation.

The glass fiber was preformed using a 1-inch glass chop 3507, and molded in the same manner as in Example 2.

The box-shaped molded product obtained was free of poor impregnation, blisters, floating fibers, and pinholes, and had good surface smoothness and surface gloss. Example 4 Molding was carried out using the formulation of Example 3 with only the curing agent replaced with 5 parts of sulfuric acid (50% aqueous solution), but the molded product obtained had no difference in appearance, strength, flame retardance, etc. from Example 2. Ta.

Example 5 A resorcinol-modified resole resin "Priorfen TD-2241" (manufactured by Dainippon Ink and Chemicals Co., Ltd.) was dehydrated to adjust its water content to 20%.

20 parts of a 41% formaldehyde aqueous solution was added to 100 parts of the prepared resin with a moisture content of 20% (resin solid content: 80%) and stirred to obtain a blend having a viscosity of 15 poise. Next, a flat mold (30? (horizontal) x 30? (vertical) x 3 mm (thickness)
) chopped strand mat (4507/Trl)
Three sheets were stacked and set, and 300 y of the above-mentioned mixture was poured into the mold at a pressure of 30 kg/Cdl temperature of 125° C. for 15 minutes.
The resulting thickness was 3m77! The condition of the molded product was good gloss with no poor impregnation, blisters, pinholes, etc. Example 6 Furfuryl alcohol-modified resol resin “Fandretsu HD-2095” (manufactured by Dainippon Ink and Chemicals Co., Ltd.)
Water was added to adjust the moisture content to 35%, and the next formulation yielded a 25 poise formulation.

Next, it was molded in the same manner as in Example 2.

The box-shaped molded product obtained had good surface smoothness and gloss, with no impregnation defects, blisters, floating fibers, pinholes, etc. Examples 7 to 10 Several types of resins were prepared by adjusting the water content of "Pryoven TD23O7" used in Example 3 by reducing the pressure or adding water.

To 100 parts of these resins, 6 parts of a 65% phenolsulfonic acid aqueous solution was added and stirred, and pressed under the same molding conditions as in Example 2. Comparative Example 4 The resol type phenolic resin used in Example 3 was charged into a flask and dehydrated under high vacuum to reduce the water content to 3.0.
%.

The prepared resin was a highly viscous resin with almost no fluidity even when tilted. It was difficult to mix a curing agent into the resin at room temperature (25°C). Therefore, the resin was heated to 40°C, 4 parts of a 65% phenolsulfonic acid aqueous solution was added to 100 parts of the resin, and the mixture obtained by forced stirring was pressed under the same molding conditions as in Example 2. Poor impregnation occurred and a satisfactory molded product could not be obtained. Comparative Example 5 Water was added to the resin used in Example 3 to obtain a water content of 55%.
I adjusted it so that it becomes .

To 100 parts of the resin, 7 parts of a 65% phenolsulfonic acid aqueous solution was added and stirred, and the resulting mixture was pressed under the same molding conditions as in Example 2. The resulting molded product was incompletely cured, the glass fibers were severely lifted on the surface, there were blisters and cavities, and the surface had no gloss at all. In this molding, 3
Similar results were obtained even when twice the amount of curing agent was used. The above results are summarized in Table-1.

Example 11 The water content of a resorcinol modified phenolic resin "Pryophene 6000" (manufactured by Dainippon Ink and Chemicals Co., Ltd.) was adjusted to 45% to obtain a resin with a viscosity of 4.5 poise.

To 100 parts of the resin, 20 parts of a 1/1 (mol) solution of furfural/paraformaldehyde was added as a hardening agent and stirred. The obtained compound was made into a bathtub-like FRP type (100
CT! l (horizontal) x 70 (1771 (vertical) x 80 (V
7! (Fukasa)) Chopped Strand Mat (45
07/M2) were stacked using the pan lay-up method. After standing for one day, the laminate was post heat treated at 80'C for 1 hour and then demolded.

The obtained molded product had a good appearance and a bending strength of 16.5 kg/
Md, tensile strength was 16 kg/Md, and oxygen index was 61.2. Example 12 The resin used in Example 2 was adjusted to have a moisture content of 30% to obtain a resin with a viscosity of 3 poise.

To 100 parts of the resin, 7 parts of a 65% aqueous phenolsulfonic acid solution was added and stirred. The resulting formulation was used in Example 1.
It was molded under almost the same conditions as No. 1. The obtained molded product had a good appearance, a bending strength of 18k9/M7i, and a tensile strength of 12.5.
kg/Md, and the oxygen index was 59. Example 13 A chopped strand mat (450y/M°) was placed on a glass plate, impregnated with the formulation prepared in Example 11 using a hand roller, and after defoaming, the surface was covered with a polyester film and cured as it was. .

Claims (1)

[Claims] 1 Consists of a resol-type phenolic resin, a curing agent, and optionally fillers, mold release agents, colorants, etc., and has a water content of 5 to 50% by weight (total weight of resin solids and water). Based on the inorganic fiber reinforcement 10
A method for molding reinforced plastics, characterized by impregnating the molded product with a concentration of up to 70% by weight and then curing without forced drying.