JPH03146534A - Rigid vinyl chloride-based resin composition for expansion and foam therefrom and its production - Google Patents

Abstract

PURPOSE:To obtain the title composition developing no skin on the surface of the resultant foam even when expanded, good in adhesivity, excellent in secondary processability, and capable of giving lightweight, large-sized foams by incorporating a rigid vinyl chloride resin of low molecular weight with a plasticizer and foaming agent such as a bicarbonate, etc., at specified proportions. CONSTITUTION:The objective composition can be obtained by incorporating (A) 100 pts.wt. of a vinyl chloride-based resin 300-700 in polymerization degree with (B) 0-20 pts.wt. of a plasticizer and (C) a total of 0.5-3.5 pts.wt. of a bicarbonate and, if needed, 0-0.5 pts.wt. of another foaming agent. The present composition is put to injection molding to obtain the other objective rigid vinyl chloride-based resin foam.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a hard vinyl chloride resin composition for foaming, a hard vinyl chloride thread-spun resin foam molded article, and a method for producing the same. More specifically, it is flame retardant, lightweight, can be used for secondary processing such as adhesion to pipes, etc., has high compressive strength, and is durable! Highly resistant to I impact, such as industrial products such as T+B repeaters, joints, drainage basins, chairs for subways and airports, automobile interior parts such as center pillars and horn butts, switch boxes, housing covers, OA cable protection covers, and telephones. The present invention relates to a hard vinyl chloride resin composition for foaming that can be suitably used in the field of electrical appliances such as line cable covers, a hard vinyl chloride thread-spun resin foam molded article, and a method for producing the same.

[Conventional technology] Foamed resin molded products are lightweight and have good insulation properties.

It is used in various molded products because it has excellent cushioning properties, does not absorb moisture, has great sound absorption and insulation effects, and has a soft appearance. As the foaming resin used for these molded products, thermoplastic resins such as soft vinyl chloride resin, polyethylene, polypropylene, polycarbonate, and modified polyphenylene oxide are mainly used.

Rigid vinyl chloride resin foam moldings are generally molded using a molding machine with a low shear rate, and are mainly molded using an extruder or press machine. Typical examples include rods, tubes, plates, picture frames, etc. These include irregularly shaped products, and many of them are extremely simple in shape.For irregularly shaped products, it is possible to manufacture complex products such as window frames with straight shapes.
The disadvantage is that products with bent shapes cannot be manufactured all at once. When the shape of the product becomes three-dimensional and rough, cutting, 16
Secondary processing such as bonding and heat bending is required.

On the other hand, injection 11! In this case, even complex shapes can be made into products in one molding process, and the product has the advantage of being highly flexible in its design. Taking advantage of these characteristics, thermoplastic resins, especially polypropylene, are used in various molded products. Polypropylene foam molded products are used for drainage masses because foam molded products are lightweight and easy to handle, and are gradually replacing concrete drainage masses.

However, it is recognized that injection molding of hard vinyl chloride resin is difficult, especially for large foam molded products, and large foam molded products made of hard vinyl chloride resin have not yet been developed.

[Problem to be solved by the invention] 9. Injection molding of hard vinyl chloride resin, especially large molded products. The reason why foam molding was not possible was due to the basic difference in injection 4114R between an extruder and an injection molding machine.
This is thought to be due to the characteristics of hard vinyl chloride resin.

In other words, in extrusion molding, the resin is extruded continuously in the cylinder and there is no stagnation, so the heat is evenly distributed, whereas in injection molding, the flow of resin in the cylinder is IT standard, and the ftI retention is This is because the decomposition is radically promoted by self-heating.

Further, the hard vinyl chloride resin is difficult to process because the decomposition of the blowing agent generates radicals and heat of decomposition, which accelerates the decomposition of the vinyl chloride resin during processing. Furthermore, in the case of injection molding, the shear rate is higher than that of an extruder or press, and shear heat is generated during molding, which further accelerates the decomposition of the vinyl chloride resin, making molding impossible.

In order to solve these problems, attempts have been made to improve processability by adding processing aids, or some processing aids are not compatible with vinyl chloride resins, so the surface of the molded product is thin. When a film is formed and adhesiveness with other molded products is adhered to, for example, a vinyl chloride resin pipe, the skin peels off and the adhesive strength decreases. Therefore, a problem arises in that secondary processing is required.

Furthermore, since vinyl chloride resin has a low thermal decomposition temperature, it is necessary to keep the dendration temperature low, but if the resin temperature is kept low, the melt viscosity increases, making injection molding difficult. Therefore, in order to improve processability, attempts have been made to add plasticizers to lower the melt viscosity, or plasticizers are not effective unless they are added to the extent that the rigidity of the molded product is insufficient.
Is the addition of plasticizer resistant to 4ti? There was a problem that it decreased sex.

In addition, if a vinyl chloride resin with a low degree of polymerization is used to lower the melt viscosity, the impact resistance will also decrease.
For example, there has been a problem in that molded products break when dropped from a high place. For molded products that require high impact resistance, adding an impact agent will increase the melt viscosity, making injection molding difficult.

Furthermore, hard vinyl chloride resins have poor thermal stability. In order to improve thermal stability, increasing the amount of stabilizer is not only an economic problem, but also the degree of effect is not sufficient.

Furthermore, hard vinyl chloride resins have the following problems. LIII. ■Due to poor thermal stability, burning occurs at the injection speed of a normal injection molding machine; ■The resin temperature cannot be raised because the molding temperature and decomposition temperature are close to each other. Therefore, the melt viscosity becomes high and the fluidity becomes poor. ■The resin remaining in the cylinder is thermally decomposed. ■Molding with high shear force generates heat and the resin thermally decomposes. ■The decomposition of the resin is accelerated by the generation of heat of decomposition of the blowing agent and the generation of radicals.

Because of the above-mentioned problems, it has been generally recognized that the foaming acid form of hard vinyl chloride resins is difficult to form.

On the other hand, in the case of olefin resins, the hardness may be due to decomposition of the resin due to the addition of the blowing agent. Since vinyl chloride resin does not cause any problems, it is currently used as foam molded products such as IE, drainage basins, etc. However, the drainage mass made of olefin resin is 11! When joining with PVC-based resin pipes,
Since there is no adhesive that adheres to non-polar olefin resins, poor adhesion occurs, leading to drainage or water leakage, and this water leakage causes pollution problems, and a solution to this problem is sought. For this reason, when connecting a drainage mass made of foamed polypropylene and a pipe made of vinyl chloride resin, a ring cut from the vinyl chloride pipe is insert-molded to facilitate the connection.

However, if you just insert mold the ring,
Although it is possible to make the connection easier structurally, it still cannot be bonded, so leakage cannot be completely prevented.

Furthermore, there is the problem of poor workability.

The present invention has been made in view of the above points. Firstly, it is possible to make injection foam molding of hard vinyl chloride resin to reduce the weight of the molded product. Secondly, it does not break even if dropped. To provide a large foam molded product that has strength and does not impair rigidity.Thirdly, it is possible to mold a foam molded product that does not generate a thin skin on the surface.Fourth, it is possible to bond. The object of the present invention is to provide a hard vinyl chloride resin composition for foaming, a hard vinyl chloride foam molded article, and a method for manufacturing the same, which can improve secondary processability.

[Means for Solving the Problems] In order to achieve the above object, the present invention has the following configuration.

That is, the composition of the first invention is 1 part of vinyl chloride resin 1001iE having a degree of polymerization of 300 to 700, and 0 to 2 parts of plasticizer for 100 parts by weight of the vinyl chloride resin.
0 parts by weight, 5 to 30 parts by weight of impact-resistant agent, and 0.5 to 3.5 parts by weight of bicarbonate and other blowing agents as blowing agents (of which blowing agents other than 9 heavy S salts are 0. ~0.5 parts by weight)
A hard vinyl chloride resin composition for foaming, characterized in that it contains a foaming hard vinyl chloride resin composition.

The structure of the second invention is made by injection molding the hard vinyl chloride resin composition for foaming of the first invention, and has a specific gravity of 1.
It is a hard vinyl chloride resin foam molded article characterized in that it has a polyvinyl chloride resin composition of 62 or less, and the configuration of the third invention uses the hard vinyl chloride resin composition for foaming of the first invention, and
Using a shut-off nozzle with a nozzle diameter of 5 to 20 mm, the shear rate at the part where the cross-sectional area of the gate part of the mold is the smallest is 0. Sx 102~5 X 10” ci
This is a method for producing a hard vinyl chloride resin foam molded article, which is characterized by injection J& molding under conditions of +/second.

The vinyl chloride resin used in the composition of the present invention may be obtained using any polymerization method among bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization, and is not particularly limited. The vinyl chloride resin used here is preferably obtained by a suspension polymerization method. It refers to a copolymerized resin that is copolymerized with vinyl monomer in an amount that does not exceed the amount used.

Examples of the copolymerizable unsaturated monomer include olefins such as ethylene and propylene, vinyl esters such as vinyl acetate and vinyl stearate, vinyl esters such as acrylic ester and methacrylic ester,
Examples include vinyl ethers such as ethyl vinyl ether and cetyl vinyl ether, unsaturated acids such as acrylic acid and maleic acid, aromatic vinyls such as styrene, and acrylonitrile, but are not particularly limited.

In addition to copolymer resins with comonomers, for example,
Vinyl chloride is added to graftable resins such as acrylic rubber, (meth)acrylic acid ester resin, ethylene-vinyl acetate copolymer resin, ethylene-(meth)acrylic acid ester copolymer resin, corded polyethylene resin, and styrene-butadiene rubber. A graft copolymer resin obtained by graft copolymerizing monomers can also be used.

These vinyl chloride resins can be used alone depending on the physical properties required for the product.

It is also possible to use a combination of two or more selected from homopolymer resins, polymer resins, and graft copolymer resins.

The average degree of polymerization of the vinyl chloride resin used is 300 to 7.
The number is 0, preferably 400 to 600. If the average degree of polymerization is less than 300, the melt fluidity will be significantly lowered, or the impact resistance of the molded product will be greatly reduced, and the molded product may break even if it is simply dropped. It is difficult to use.

In addition, if the average degree of polymerization exceeds 700, the melt fluidity will decrease significantly, making injection molding impossible.
When injection molding is attempted by increasing the dynamicity of the resin, the temperature of the resin approaches the thermal decomposition temperature, and the occurrence of thermal decomposition cannot be suppressed, so thermal decomposition progresses gradually, resulting in foaming of the planarized vinyl thread resin. It becomes impossible to manufacture molded products.

In addition, in order to reduce the melt viscosity, a copolymer resin of a vinyl chloride monomer and a copolymerizable monomer and a vinyl chloride monomer are also used.
It is preferable to use a copolymer resin with a resin capable of grafting the body, and the amount used is selected from the acceptable range of moldability and rigidity. When fit mobility is required, the melt viscosity can be improved by using a single textured resin with a low degree of polymerization, or by using a copolymer resin with excellent fluidity alone or in combination. However, since the rigidity decreases, the degree of polymerization of the homopolymer resin and the degree of copolymerization must be adjusted according to the required physical properties of the product.
The amount of the four fats to be added may be selected appropriately. In order to improve the rigidity, a resin with a high degree of polymerization and a copolymer resin with excellent fluidity may be used in combination.

Plasticizers that can be used here include phthalic acid esters such as dioctyl phthalate, aliphatic esters such as dioctyl adipate, 5-dioctyl azelate, etc. ), ';: Acid ester type, aromatic polyester of trioctyl trimellitate 11! Basic acid ester types, epoxy types such as epoxidized soybean oil, polyester types, phosphate ester types such as trinonyl phosphate, tricresyl phosphate, etc. are excluded, and these i+j! ! , il+ may be used alone or in combination of two or more.

The amount Lk added of the plasticizer is 0 to 20 parts by weight based on 100 parts by weight of the vinyl chloride resin. 1st place kikiya is 2
If it exceeds 0 parts by weight, the melt fluidity is greatly improved, but
It is impossible to use it as a structural material because of its reduced rigidity. Preferably, when using vinyl chloride resin with a high π degree, which is plastic because it can be used without reducing rigidity in less than 5 electric regions, it is necessary to increase the amount of 1f plasticizer used. , Th) When using a vinyl chloride resin with a low degree of polymerization, it is preferable to use a small amount of plasticizer. In the case of a high degree of polymerization, the rigidity decreases depending on the amount of plasticizer added, so it is difficult to flow in the melt tank. It is necessary to select the amount of added ITl to balance the properties and rigidity. Therefore, in order to increase the fluidity of the melt tank, if ri (plastic agent is added to
! This will impair the rigidity of the 1J product, making it impossible to use it as a structural material. Bending ratio: 12,00
If it is below 0 kg/c-, the pressure line strength will be low, so for example, a drainage basin may be deformed or destroyed when a heavy wheel such as a truck rides on it, causing problems with flooding.6 To solve this problem, if a filler with a large aspect ratio is added, although the rigidity improves as the amount added increases, the melt fluidity also decreases in proportion to the amount added, making molding difficult. There is no particular restriction on adding the plasticizer to the extent that it can be molded, but the amount of plasticizer used is limited in fields where rigidity is required. However, depending on the field of the product, the addition amount can be selected from IS, which improves processability with a small addition. The amount added cannot exceed 20 parts by weight.

Examples of the impact-resistant agent used in the group
Ethylene-vinyl acetate copolymer resin, ethylene-ethyl (
meth)acrylate copolymer resins, polyester resins, acrylic ester resins, etc. and ester resins,
Acrylonitrile-butadiene-styrene (polymer resin, methyl (meth)acrylate-tutadiene-styrene copolymer resin that is partially crosslinked with an acrylic acid ester resin and an impact-resistant agent obtained by graft-copolymerizing agglomerated vinyl heptamer) etc. can be mentioned.

These impact-resistant agents may be used alone or in combination of partially non-crosslinked impact-resistant agents and partially cross-linked impact-resistant agents, or two or more of each may be selected and used in combination. do not have.

The amount of the impact-resistant agent added is 5 to 30 parts by weight based on the amount of vinyl chloride yarn processing fat 10 parts by weight. The amount of 5 insects 1
．． ), the impact resistance will be insufficient and the product will be destroyed just by dropping it at 21G. The amount added is 30
If it exceeds the overlapped portion, the impact resistance will either be improved or the melt viscosity during injection molding will increase, making injection molding impossible. When injection molding is performed at high temperatures and pressures, vinyl chloride resins undergo high shear, which generates heat and thermally decomposes. That is, when a conventional partially crosslinked methyl (meth)acrylate-butadiene-styrene copolymer resin-based impact agent is added, the melt viscosity increases, making injection molding difficult. Therefore.

If the amount of partially cross-linked impact agent is increased, the melt viscosity will increase, so a partially crosslinked impact agent should be used in combination to prevent the increase in melt viscosity and at the same time reinforce the impact properties. is desirable, and the ratio can be adjusted depending on the required physical properties.

If the emphasis is on processability, increase the proportion of non-partially cross-linked impact resistance, and when impact resistance is required, increase the amount of partially cross-linked impact resistance within the range that processability allows. The preferred ratio of zero-partially crosslinked impact agent to non-crosslinked impact agent is +00/0 to 50/
50 is good 0 Products using impact resistance agents that are not partially crosslinked have lower impact strength than products using impact resistance agents that are partially crosslinked, so use more than the amount of impact resistance agents that are partially crosslinked. is not desirable? In the case of a product that requires iL-activity, it is possible to select and use a vinylide resin with a low degree of polymerization in addition to the impact-resistant agent.

If the degree of polymerization of vinyl chloride resin is increased, the fluidity will be lowered or the impact resistance will be improved, so the amount of impact agent added may be small.On the other hand, if the degree of polymerization is lowered, the fluidity will be improved. Since the #Ig resistance of the material decreases, the addition of 1iIIJ impact agent r4 increases the yellowing and fluidity decreases. Therefore, it is necessary to appropriately select the degree of polymerization of the vinyl chloride resin and the amount of impact-resistant agent added.

Stabilizers are typically used in the compositions of the present invention. Stabilizers used include 1, for example, 311! basic lead sulfate,
A-free salts such as dibasic lead phosphite, lead silicate, basic lead carbonate, and hydrotalcite; lead, cadmium, barium, calcium, and aluminum-based soaps such as lead stearate and cadmium stearate; Examples include organic tins such as laurate, malate, mercapto, and sulfide stabilizers, and one or more of these stabilizers may be used.
The amount of the stabilizer to be added, which may be used in combination with the above two, is 1 to 1) the amount of insect repellent to the amount of heavy water of the agglomerated vinyl resin. If the amount is less than 1 part by weight, the thermal stability will be insufficient, and combined with shear heat generation and radical decomposition of the blowing agent, black 4 francs will occur in the product, and in severe cases, vinyl chloride resin will deteriorate. It can also decompose, and injection gases, especially decomposition gases, can be generated and greatly stain the working environment. If the amount of the stabilizer added exceeds 101 parts, the thermal stability will be improved and the occurrence of decomposition during injection molding will be prevented, but the effect will not be commensurate with the amount added and there will be economic problems. The stabilizer is appropriately selected according to the required physical properties and shape of the product. That is, suitable molding can be achieved by appropriately using stabilizers known in the art.

A lubricant can be used in the composition of the invention. Examples of the lubricant used include hydrocarbons such as natural paraffin and low molecular weight polyethylene.

Fatty acids such as stearic acid, lauric acid, and erucic acid, aliphatic alcohols such as cetyl alcohol and stearyl alcohol, and fatty acid amides such as stearic acid amide and methylene bisstearamide.

Examples include lower alcohol esters of fatty acids such as butyl stearate, polyhydric alcohol esters of fatty acids such as glycerin monostearate, and higher aliphatic alcohol esters of higher fatty acids such as stearyl stearate. These lubricants may be used alone or in combination of two or more for PJ. Addition of the lubricant1. 'E is 1 to 10 parts by weight based on 100 parts by weight of the vinyl chloride resin. If the amount of the blended resin is less than 1 part, it will stick to the screw of the molding machine and promote thermal decomposition of the vinyl chloride resin. occurs. If the amount exceeds 10 parts by weight, the melt viscosity during injection molding will be lowered and the melt fluidity will be improved, but in general, if a large amount of lubricant is added, there will be no compatibility and the die exit eye stains during pelletizing. Especially during injection molding, separation of the layer 'A' occurs and the impact resistance decreases. Preferably, 2 to 5 regular bk parts are appropriate. The lubricant is
Rather than using a single lubricant, choose an internal lubricant or an external lubricant as appropriate.
It is preferable to use it together with other people to adjust the lubricity.

When the melt Mte property is important, it is preferable to use a large amount of an internal lubricant having high internal lubricity; that is, molding can be performed by using an appropriate amount of a lubricant known in the art.

The blowing agent used in the composition of the present invention includes:

For example, inorganic salts such as ffi carbon IV salt, azo type such as azodicarbonamide, sulfohydrazide type such as p,p'-oxy-bis=(benzenesulfonylhydrazide), N
, N'-dinitroso-(dimethyl terephthalate) and the like.

These blowing agents are used in combination with bicarbonate or other blowing agents. ! 11 Carbonates include ammonium hydrogen carbonate and potassium hydrogen carbonate.

Examples include calcium hydrogen carbonate, cobalt potassium hydrogen carbonate, cesium hydrogen carbonate, sodium hydrogen carbonate, nickel hydrogen carbonate, magnesium hydrogen carbonate, potassium magnesium hydrogen carbonate, lithium hydrogen carbonate, and rubidium hydrogen carbonate. Among these, sodium hydrogen carbonate and magnesium hydrogen carbonate are particularly preferred.

The amount of the foaming agent added is 0.5 to 3.5 parts by weight based on 100 parts by weight of the vinyl chloride resin. If the amount of the foaming agent added is less than 0.5 parts by weight, the foaming ratio will be low, which is not preferable in terms of weight reduction, and it will not be economical.
Even if more than 5 parts by weight is used, the foaming efficiency does not decrease in proportion to the amount added; on the contrary, the surface becomes rough, there is no solid layer, the impact resistance decreases, and the product price (+11) decreases. When using a blowing agent other than bicarbonate, especially azodicarbonamide, the vinyl chloride resin may be decomposed due to the heat of decomposition of the blowing agent and the generation of radicals, which may be generated inside the injection molding machine and cause sintering. Poor impact resistance, +1!
Due to the presence of raw gas, etc., the product may be defective on the outside.

It is difficult to continue stable molding for a long period of time.

Therefore, the amount of the blowing agent other than the bicarbonate such as azodicarbonamide is 0 to 11 parts. Preferably 0
．． It is 2 to 0.3 parts by weight. If more than 0.5 parts by weight is added, there will be problems with thermal stability and molding cannot be continued.However, when using ffi>&Wkm, there is no heat generation due to decomposition or an endothermic reaction, and radical Since there is no generation of , the decomposition of the resin is not promoted.

However, in the case of injection molding, sink marks often occur during the cooling process. In order to prevent this sink mark, the mold temperature should be set at 20~60℃.
℃ to prevent local shrinkage caused by supercooling caused by rapid cooling. When the cooling temperature is lower than 20°C, shrinkage increases and sink marks are likely to occur. Also, the cooling temperature is 60℃
Exceeding this will cause over-foaming, which will easily cause problems such as the size, shape, and cavities of the product.From a cost standpoint, it is necessary to shorten the cooling time as much as possible, but if the cooling time is short and the inside cannot be cooled, There is a risk of causing back blister.

Furthermore, in addition to preventing sink marks due to mold temperature, addition of a small amount of azosicabonamide prevents sink marks due to shrinkage caused by rapid cooling. The amount added is 0 to 0.5 parts by weight. As mentioned above, if it is not added, sink marks can be prevented by adjusting the cooling rate of the mold. Addition of azosicabonamide can prevent sink marks due to the gas generated.

If the amount added exceeds Q, 5 g, the thermal stability will be impaired due to the generation of radicals and heat of decomposition resulting from decomposition, and molding will become impossible.

Other additives and fillers used in the present invention.

There is no restriction in any way that additives known in the art, such as color, antioxidant, and ultraviolet inhibitor, may be added to the extent that the purpose is not impaired.

Book 9. The molding strip used for IJl is a shut-off nozzle with no stagnation, the nozzle diameter is 5 to 20 mm, and the shear rate at the part of the mold where the cross-sectional area of the gate part is the smallest is 0. Sx 10" to 5 X In"C 37 seconds.

Other molding conditions include cylinder temperature of 160-200℃;
The nozzle temperature is 180~200℃, the screw peripheral speed is 8~18-7 minutes, the injection pressure is 60~120kg/cm, and the molding time is shortened by using a multi-station mold molding machine. preferable.

The nozzle part is a shut-off nozzle that does not stagnate, and a check ring is provided at the tip of the screw to prevent stagnation and backflow of resin, thereby minimizing the amount of resin stagnation in the cylinder. When a backflow occurs, the resin that has been heated once is kneaded by the screw again, so the resin, which has poor thermal stability, is basically subjected to a second thermal history, causing thermal decomposition and resulting in poor molding. Furthermore, resin leakage from the tip can be prevented and the amount of molten material injected can be made constant, resulting in stable moldability and a reduction in product defect rates.

The nozzle diameter is 5~20cm, and the shear rate is 0.5xlG''~5x102cm at the minimum cross-sectional area of the mold gate.
It is appropriate to perform injection molding under the conditions of 1/sec. If the nozzle diameter is smaller than 5ms, the shear rate must be increased by 5
10" C17 seconds. If the shear rate increases, the resin will generate heat and, in extreme cases, will cause decomposition. To prevent these exothermic decompositions, stabilizers and lubricants must be added. Increasing the amount is either ineffective or there is a limit to how economically it can be used.In addition, the injection pressure must be high, forcing the mold to be filled with a highly viscous composition. There are cases where the limit of thermal stability of the resin is exceeded.If high-pressure filling is used, the surface of the molded product will show swanil marks and the commercial value will be drastically reduced.In other words, the nozzle diameter of the molding machine or the minimum mold The shear rate when the composition passes through the cross-sectional area is 5 x 10"
cm If the time is greater than 7 seconds, the above-mentioned problems will come into focus.

If the nozzle diameter is larger than 20-■, the shear rate is 0.5 cm.
/second, and decomposition of the resin due to heat generation is prevented, but the mold will be insufficiently filled, and the product's functionality will not be satisfied. In addition, the expansion ratio decreases because the heat generation is small. To prevent this, measures can be taken to raise the cylinder temperature to lower the melt viscosity and promote the decomposition of the blowing agent to improve the expansion ratio, but as the resin temperature increases, the thermal decomposition temperature of the resin increases. If they get close to each other, the decomposition of the resin will be accelerated, making it impossible to actually mold it.

Therefore, the conditions that can be molded as a product are whether the nozzle diameter is 5 or more.
20 cm, and the shear rate is preferably 0.5 x 10' to 5 x 1102 a/sec at the minimum cross-sectional area of the gate part of the mold.

The decomposition rate of hard agglomerated vinyl resin due to heat in the cylinder is ♀ (When the cylinder temperature is 160 to 200°C, the decomposition time for solid molding is more than 1 hour, which can cause special problems in molding. Even if the residence time exceeds 1 hour, problems such as decomposition of the resin will not occur, and if azodicarbonamide is used as a blowing agent in foam molding, it will decompose in 5 to 10 minutes, so the molding characteristics The resistance to trouble is extremely small.

Therefore, it is desirable to minimize the residence time in the molding machine.It is undesirable to prolong the residence time due to the troubles that occur during the R & shape pile, as this will lead to decomposition of the vinyl chloride resin.Therefore, the residence time is 15 Good ef for less than a minute
When using the flljpenta-acid salt, injection molding is possible because it has a relatively low effect of promoting decomposition of vinyl chloride resin compared to azodicarbonamide, but it is preferable to minimize the residence time.

By using a multi-station mold with 3 to 6 station molds to minimize the residence time, molding can be completed using only measuring time, injection time, and travel time, which prevents resin decomposition. I'll do it. In addition, in general injection molding machines, cooling time is required compared to multi-station models, so the time spent in the cylinder or nozzle is significantly increased, and the resin decomposes due to residence. However, decomposition products accumulate in the molding machine and gradually become injected into the product.

In general, the relationship between the length of time between cooling, metering, injection, and movement is such that the cooling time is longer, which acts to promote the decomposition of the resin. Therefore, foam molding has extremely poor molding stability compared to solid molding. This is because the molding temperature range and the decomposition temperature range are close to each other, so even in the case of solid molding, it is difficult to mold at temperatures exceeding 200°C. A suitable combination of lubricants is required to prevent resin buildup within the cylinder. In this combination, it is necessary to improve heat resistance by preventing adhesion to cylinders, screws, etc., and at the same time preventing heat generation due to shearing of resins together.

In particular, it is important to use a larger amount of internal lubricant, which has good internal lubricity to prevent heat generation due to friction between resins, than external lubricant.

In order to increase the foaming ratio, is it necessary to increase the resin temperature to promote the decomposition of the blowing agent? If the resin temperature is increased, the decomposition of the agglomerated vinyl resin will also be accelerated, making injection molding impossible. become. When the cylinder temperature exceeds 200°C, the resin begins to blacken during molding due to the combination of the generation of radicals due to the decomposition of the foaming agent and the decomposition of the resin due to heat.

On the other hand, if the cylinder temperature is lower than 175°C, the foaming efficiency of the blowing agent decreases and at the same time the melt viscosity increases, making it impossible to fill the mold without a high injection pressure.

High injection pressure! ! ! Although the melt viscosity decreases due to the generation of intermittent heat generation, the resin temperature also rises, causing local decomposition of the resin. Therefore, if the resin temperature inside the cylinder exceeds 200°C, the resin will begin to decompose, so it is necessary to store the resin at a humidity below this temperature range. This is a possible condition. The resin temperature can be selected depending on the required expansion ratio.

Does the screw circumferential speed vary depending on the compression ratio?
A speed of 18 m/min is appropriate, and if the process ends in 8-1 min, the vinyl chloride resin will not be sufficiently melted. In order to melt the resin, it is necessary to raise the temperature inside the cylinder to over 200°C, and when this temperature range is reached, the resin begins to decompose, and black matter gradually appears in the product. In addition, even if the unmolten composition is molded at high injection pressure, it will not be possible to completely fill the mold and the product will not be produced.If the zero circumferential speed exceeds 18 cm/min, the cylinder temperature will locally increase. In particular, if a screw with a high compression ratio is used, this will be further accelerated and the decomposition of the resin will be promoted.

Furthermore, due to the shear heat generated by the screw, the salinity of the entire resin increases, and the resin decomposes over the entire surface, resulting in a complete decomposition state, and chlorine gas is blown out during molding. Therefore, the peripheral speed is suitably in the range of 8 to 18-/min. The compression ratio for hard screws is 1.5 to 2.5.
It is necessary to reduce the local heat generation caused by the circumferential speed of the screw.

[Function] The vinyl chloride resin in the present invention has a degree of polymerization of 300 to 300.
It has a low molecular weight of 700, gels quickly during kneading, and has a low melt viscosity, making it effective for injection molding, especially foam injection molding.

Furthermore, in foam molding, the decomposition of the resin is accelerated due to heat generation due to the decomposition of the foaming agent, radicals generated by decomposition, shear heat generated by the screw, and high temperature heating of a part of the cylinder, so the melt viscosity of the injection molding can be reduced. It is effective to keep it as low as possible. In order to lower the melt viscosity, it is necessary to lower the degree of polymerization of the resin within the range allowed by the rigidity and to add a plasticizer.

The reduction in thermal stability caused by the generation of decomposition heat and radicals due to the decomposition of the blowing agent may be effectively avoided by using bicarbonate, which is a blowing agent that does not generate radicals, or may have the drawback of causing sink marks on molded products.

Sink marks in molded products can be effectively prevented by increasing the mold temperature and performing post-foaming appropriately, and by using a foaming agent other than bicarbonate in combination to perform post-foaming.

If a resin with a low degree of polymerization is used to lower the melt viscosity, the impact resistance will decrease;
It is effective to add an impact-resistant agent to h. Since the addition of an impact-resistant agent causes an increase in the melt viscosity, it is preferable to use a non-partially cross-linked impact-resistant agent having a relatively low melt viscosity blended with a partially-cross-linked impact-resistant agent.

Further, the hard vinyl chloride resin composition for foaming enables injection molding of a hard vinyl chloride resin foam molded article.

Furthermore, in the present invention, the molding conditions are adjusted to a nozzle diameter of 5 to 20 μI.
The minimum cross-sectional area of the gate of the mold is the shear rate or 0.
．． Limiting the nozzle diameter and shear rate to 5 x lO'~5 x 10" c/sec prevents heat generation and decomposition of the resin,
This is effective in further increasing the foaming ratio without causing insufficient filling of the mold.

With the above configuration, a large injection foam molded product made of hard vinyl chloride thread resin can be manufactured.

[Example] Examples are shown below, but the present invention is not limited thereto. In the following examples, "parts" represent "parts by weight." Furthermore, the quality of the vinyl chloride resin set X & used in the examples and the products obtained therefrom were evaluated by the following method.

■Measurement of degree of polymerization of agglomerated vinyl resin Compliant with JIS K-6721.

■Gravity Compliant with JIS K-7112.

■Thermal stability The appearance of the injection molded product was evaluated on the following five scales.

◎ Smooth surface and good color tone.

○ The surface is smooth and the gate opening is slightly discolored.

Δ　The surface is a little rough and the whole thing is a little discolored.

× There is something special about grilled rice with a rough surface.

XX It burns and generates gas.

(2) Drop weight test 1-1 A 2 kg steel ball with a diameter of 60 mm was dropped from above the 35c opening into the gate opening, and cracking and separation were evaluated on a 5-grade scale.

◎ Smooth surface with no cracks or breaks.

○ The surface is smooth and the gate is slightly scratched.

8. There are some cracks on the surface.

× Quite large cracks appear on the surface.

XX It cracks and scatters.

■ Drop test The molded product itself was dropped from a height of 1.2 m, and its appearance was evaluated on the following five scales.

◎　The rib part will not crack.

○ The tip of the rib is slightly dented.

△　There are cracks in some parts of the ribs.

× The rib and its surroundings are cracked.

XX　The whole thing flies up and scatters.

■Compression test The molded product was placed in a compression testing machine in the same position as in use, and a load of 4000 kg was applied.The appearance of the molded product was evaluated on the following five scales.

◎　The rib part will not crack.

○ The tip of the rib is slightly dented.

Δ There are cracks in the rib installation.

× Ribs and their surroundings are cracked.

XX　The whole thing cracked and scattered.

■External shape The molded product was evaluated in five stages according to its shape.

◎ Completely molded product.

○ The rib part is a little short shot.

Δ　The rib part does not get all the heat.

× A short shot of part of the main body.

×X Most of the main body is a short shot.

■ Adhesive Adhesive 216 manufactured by Miki Kagaku Kogyo ■ was applied to the outer circumference of the pipe and the inner surface of the invert outlet, and 46 pieces were applied, and two people pulled and tested.

O can't be missed.

× It comes off.

■Bending elastic modulus A test piece was prepared by cutting the rib portion according to JIS K-7203.

◎ Elastic modulus ≧2.0×104 Q　　　1.5≦Modulus＜2.0 △　　1.2≦Modulus＜1.5 × Elastic modulus <1.2 kg/am' [phase] sink mark The molded product was evaluated on the following five scales based on its external shape.

◎ Completely molded product with no sink marks.

○ Very few sink marks.

△　He has a little beard.

×　Irregularities are clearly visible.

XX Large unevenness.

(Examples 1 to 4. Comparative Examples 1 to 2) Agglomerated vinyl resin: Resin with a degree of polymerization of 650 (hereinafter referred to as
(referred to as P2S5), resin with a polymerization degree of 700 (hereinafter referred to as P2O
3), resin with a polymerization degree of 800 (hereinafter referred to as P2O3), resin with a polymerization degree of 350 (hereinafter referred to as P2S5) 1
25 kg each of resin with a polymerization degree of 450 (hereinafter referred to as P2S5) and resin with a polymerization degree of 500 (hereinafter referred to as psoo)
and BM(N) and BK-110OL manufactured by Sankyoki Co., Ltd. and TVS#1400. manufactured by Nitto Kasei ■ as tin stabilizers for 100 parts by weight thereof. 68-IF, a partially cross-linked acrylonitrile-butadiene-styrene copolymer resin manufactured by Japan Synthetic Rubber ■, was used as an impact resistance agent, DOP was used as a plasticizer, and EW-100 manufactured by Riken Vitamin ■ was used as a lubricant.
, 0PL-06, and 5L-900 were blended as shown in the table and put into a 100L high-speed mixer (model H-100) manufactured by Olympia Kakoki ■, heated to 120℃, and then heated to 60℃.
The powder compound was cooled to 0.degree. C. and taken out. The compound was extruded by twin screw extrusion in different directions for 50 m manufactured by Mitsubishi Heavy Industries ■!
& (MD-50 type): 1:10℃,
C2140℃, CHI: 150℃, AD:I
40℃, D: 140℃, Screen mesh: 60Me
x1 piece.

Pelletization was carried out under the conditions of 1 sheet of 80Me′ and rotation speed: 25 rpm. Further, 0.5 parts by weight of DOP was added to the pellet described above to wet the surface, 1 ffi part of bicarbonate of soda was added as a blowing agent, and 0:lf of azosicabonamide was added to the pellet.
i parts were mixed in a tumbler.

The beret produced in this way is Hettinga Equ.
TCM shape molded TCM5k manufactured by ipsent Inc.
g Molding a) was molded and injection molded into a drainage mass mold under the conditions shown in Table 1. The results are listed in Table 1. still,
A shaft-off nozzle with a nozzle diameter of 1.0 cm was used.

In addition, unless otherwise specified, the middle value of each numerical value is seconds, temperature is °C, rate is %, and speed is c.
m/sec. Unless otherwise specified, it means that there is no unit. The same applies to the following examples unless otherwise specified. Furthermore, the term "shear rate" in Table 1 refers to the shear rate at the portion where the cross-sectional area of the gate portion of the mold is the smallest, and is the same in the following tables.

(Main text, below in the margins) As is clear from Table 1, the degree of polymerization of vinyl chloride resin,
By selecting the amount of plasticizer and the amount of impact-resistant agent, it is possible to clear the physical properties of [1]. When the degree of polymerization exceeds 700, the melt viscosity increases significantly, resulting in one-foam injection molding.
Gradually, cracks appear in the fired product, and cracks and cracks appear in the fired product during the drop weight test. It is also clear that when a resin with a low degree of polymerization is used, the impact resistance tends to decrease.

(Example 5, Comparative Examples 3 to 6) The vinyl chloride homopolymer resin was P2S5. Impact resistance agent is 68K
The test was carried out in exactly the same manner as in Example 2, except that DOP was used as the plasticizer and DOP was blended as shown in the second notation. The results are listed in Table 2. For reference, the results of Example 2 are shown in Table 2.

(Raiko, hereafter blank) As is clear from Table 2, the 1111 elastic modulus of P2S5, a vinyl chloride resin with a low degree of polymerization, decreases when the amount of plasticizer exceeds 20 PHR. If no plasticizer is contained, the melt viscosity will be high, the thermal stability will be poor, and the falling weight impact will be low. Adding an impact-resistant agent increases the melt viscosity, making it necessary to add a number agent. The addition amount is 15 parts or less.

(Example 6, Comparative Examples 7-8) 68K-IF of the impact resistance agent of Comparative Example 3.4.5 in Table 2
450, which is a partially non-crosslinked ethylene-vinyl acetate copolymer resin manufactured by Dainippon Ink V4.
- Example 2 above except that P was replaced according to Table 3.
It was molded using the same strip. The results are shown in Table 3. For reference, the results of Comparative Examples 3, 4, and 5 are listed in Table 3.

(Raiko, hereafter blank) As is clear from Table 3, 68K-I of partially crosslinked acrylonitrile-butadiene-styrene copolymer resin.
The melt viscosity of F increases with the amount added. On the other hand, 450-P, which is an ethylene-vinyl acetate copolymer resin that is not partially crosslinked, has a smaller increase in melt viscosity than the partially crosslinked type, but it is seen that the impact resistance is improved to a lesser degree.

Therefore, it is clear that by combining these, a composition that does not contain a plasticizer can satisfy the cost and material properties.

(Examples 7 to 9) Tests were conducted under the same conditions as in Example 2, except that the vinyl chloride resin P2S5 in Table 2 and the impact resistance agent were changed as shown in Table 4. The results are listed in Table 4. In addition, agglomerated vinyl resins other than P450 in Table 4 are P430 (
Degree of polymerization: 430. Ethylene content: 2.5%),
P510 (ff1 degree: 510. Contains propylene)
ii): 4.4%), P 450G (degree of polymerization: 450, z tyrene-ethyl acrylate [1
fat content M5.1%).

In addition For reference, the results of Comparative Example 4 are shown below. Recorded in Table 4 and lost.

(Gourd, hereafter in the margin) Table 4 As is clear from Table 4, copolymer resins with low melt viscosity have poor impact resistance, so it is safe to increase the impact resistance, but plastic There is no need to lower the melt viscosity by adding a copolymer resin.Since the viscosity of the copolymer resin is low, the moldability is good, which is clear from the excellent external shape.

(Example 1 O1 Comparative Examples 9 to 11) 25 kg of P 450 as a vinyl chloride homopolymer resin and 100 parts by weight thereof, TC manufactured by Mizusawa Kagaku Co., Ltd. as a lead-based stabilizer, DSL manufactured by Sakai Kagaku ■, and an impact resistance agent. as 11
68K-IF made of this synthetic rubber, DO as a plasticizer
P, as a lubricant, S C-100 manufactured by Sakai Chemical ■, manufactured by Riken Vitamin ■ (7) EW-100, 0PL-06SL-90
0 as listed in Table 5, Olympia Kakoki■
The powder compound was put into a 100L high-speed mixer (H-100 model) manufactured by Co., Ltd., and heated to +20"C, then cooled to 60"C, and the powder compound was taken out. The powder was extruded in different directions by 50 m5 twin screw extrusion a manufactured by Mitsubishi Tsume Kogyo (KMD-50 mold).
Tecl: 170 ”C1C2: 180”C
1C5: 190℃, AD: 190'O, D: 1
90'C! , screen mesh: 60Me'×1 sheet, 80Me'×1 sheet, rotation speed: 25 rpm. 0.5 parts by weight of DOP was added to the pellets to wet the surface, and the pellets were molded under the same conditions as in Example 2, except that the conditions for the blowing agent were changed as shown in Table 5. The results are listed in Table 5.

(Raiko, hereafter blank) As is clear from Table 5, in the case of solid injection molding,
Although there are no particular problems with moldability, thermal stability, physical properties, etc., it is clear that when zero foaming with a large specific gravity is blended with a high melt viscosity, the thermal stability deteriorates and the physical properties are insufficient.

(Example 12, Comparative Examples 12 to 14) Except for changing the metering time, plasticization rate, injection speed, injection pressure, injection time, residence time, cylinder temperature, and nozzle temperature as shown in Table 6, The test was conducted in exactly the same manner as in Example 10 in the table. The results are listed in Table 6. In addition, as shown in Table 6, as a comparative example, PP, which is a resin other than PVC,
[Mitsubishi Yuka ■ BCO3GS] was used, and the same amount of the foaming agent was added without using the plasticizer used for adding the foaming agent.

For reference, the results of Example 10 are listed in Table 6.

(Gourd, hereafter blank) As is clear from Table 6, when the residence time becomes long, vinyl chloride resin has poor thermal stability, so it decomposes and causes poor physical properties and appearance of the molded product. PP can be used as a product. However, when adhering vinyl chloride pipes, etc., PP
It is clear from Table 6 that it cannot be bonded because it is non-polar and there is no suitable adhesive.

(Example 12, Comparative Examples 15 to 17) Tests were conducted under the conditions of Example 11 listed in Table 5, except that the shutoff nozzle diameter was changed as listed in Table 7. The results are listed in Table 7. The specific gravity of the solid is 1.
It was 28. The unit of the shutoff nozzle diameter is C.
It is 11. For reference, the results of Example 11 are listed in Table 6.

(Laikong, hereafter blank) Table 7: At high shear rates, the vinyl chloride resin decomposes, and conversely, at low shear rates, it cannot be filled. It is clear from Table 7 that a suitable shear rate is required.

(Examples 13-14. Comparative Examples 18-19) Tests were conducted under the conditions of Example 11 in Table 5, except that the mold temperature and blowing agent were changed as shown in Table 6. The results are listed in Table 6.

(Raiko, hereafter in the margin) It is clear from Table 8 and Table 9 that when only sodium bicarbonate is used, sink marks occur depending on the mold temperature.

(Examples 15-16, Comparative Examples 20-21) Tests were conducted under the conditions of Example 11 in Table 5, except that the type and amount of blowing agent were changed as shown in Table 9. The results are listed in Table 9.

(Raiko, hereafter in the margin) From Table 9, it is clear that sink marks can be prevented by using sodium bicarbonate in combination with Ajisicaponamide.

[Effects of the Invention] According to Kinoe 171, a hard-coated vinyl resin composition of low molecular weights f and j with a degree of polymerization of 300 to 700 is used, and additives are used. By specifying 1gA and the amount and further limiting the molding conditions, (1) a decrease in impact resistance and the generation of radicals due to a low degree of polymerization are prevented, and a hard vinyl resin molded product, especially,
It can be used as a resin composition for foamed molded products, and (2) injection molding can reduce the weight and size of hard vinyl chloride resin molded products and has sufficient strength to prevent breakage even when dropped. (3) Even when foamed, a thin skin does not form on the surface of the molded product. Therefore, it has excellent adhesive properties and improves secondary addi- tivity. A hard polyvinyl chloride resin composition for industrial use in foaming, which has various advantages, such as being able to produce large-leaf foam injection molded products such as drainage masses without loss of rigidity. Furthermore, it is possible to provide a hard vinyl chloride resin-induced foamed molded article and a method for producing the same.

Claims (3)

[Claims] (1) 100 parts by weight of a vinyl chloride resin having a degree of polymerization of 300 to 700, and 100 parts by weight of the vinyl chloride resin, 0 to 20 parts by weight of a plasticizer, and 5 to 5 parts by weight of an impact resistance agent.
30 parts by weight and 0.5 to 3.5 parts by weight of bicarbonate and other blowing agents as blowing agents (of which, blowing agents other than bicarbonate are 0 to 0.5 parts by weight). A hard vinyl chloride resin composition for foaming, comprising: (2) A hard vinyl chloride resin foam molded article, which is formed by injection molding the foamable hard vinyl chloride resin composition according to claim 1, and has a specific gravity of 1.2 or less. (3) Using the hard vinyl chloride resin composition for foaming according to claim 1 and using a shut-off nozzle having a nozzle diameter of 5 to 20 mm, Shear rate is 0.5×10^2 ~
A method for producing a hard vinyl chloride resin foam molded article, which comprises injection molding at a rate of 5 x 10^2 cm/sec.