The Influence of Bottle Mouth Design and Content Properties on the Selection of Lotion Pump and Treatment Pump

01 Selection Based on the Caliper/Neck Specification Matching the Lotion Pump and the Plastic Bottle or Cream Bottle

The matching of the lotion pump or treatment pump and the bottle mouth is mainly based on screw thread pairing, which follows a general standard within the industry. Generally, suppliers manufacture lotion pump products according to this standard, and customers select the appropriate pump based on these specifications to fit their plastic bottle.

· Common neck diameters: 18mm, 20mm, 22mm, 24mm, 28mm, 33mm, 38mm

· Common finish specifications: 400, 410, 415

The bottle mouth of the plastic bottle or cream bottle is formed by injection molding, which offers a more stable process, higher dimensional accuracy of the mouth, and higher thread precision, meeting elevated sealing requirements. Regarding the bottle mouth structure of the product, the following aspects are generally considered:

1. Shape: Under normal circumstances, the shape of the bottle mouth is designed to be circular. A circular shape is more conducive to ensuring the dimensional accuracy of the bottle mouth, achieving better sealing cooperation with the cap, and optimizing the wall thickness distribution of the plastic bottle body during blow molding.

2. Bottle Mouth Structure: It is generally divided into a threaded structure and a snap-on structure. The threaded structure is more conducive to the sealing effect of the fit between the plastic bottle or cream bottle and the cap. It is frequently used in pharmaceutical packaging, liquid beverages, and cosmetic cream bottle packaging. Combined with various screw caps, safety caps, spray heads, treatment pump options, and lotion pump designs, it offers high sealing reliability. The size and form of the thread can be flexibly selected according to product needs. The snap-on structure is commonly used for solid or paste packaging, but can also be used for liquid packaging. Its advantage is convenience of use, making it suitable for high-speed filling. However, when used for liquid packaging in a plastic bottle, careful attention must be paid to the design of the cap material, sealing structure, and interference fit, while maintaining proper process control to ensure its sealing performance.

3. Bottle Mouth Size: For PET materials used in a plastic bottle, the bottle mouth size is relatively flexible. However, for PP materials, which are more suitable for molding a wide-mouth cream bottle or jar, the bottle mouth should not be too small; otherwise, it will significantly affect product molding and wall thickness distribution. Generally, the ratio of the bottle body diameter to the bottle mouth diameter is less than 2 times.

02 Selection Based on the Viscosity/Fluidity Characteristics of the Liquid Content

Brand owners will have specific data regarding the viscosity/fluidity of the liquid content, but for lotion pump and treatment pump manufacturers, this data is often lacking. Usually, the liquid content can be poured into a beaker, and the determination can be made based on the condition of the liquid surface:

A. If the liquid surface can reach a horizontal level instantly without leaving any traces on the surface, all lotion pump varieties, treatment pump options, and derived pumps can be used. One only needs to consider the characteristics of the liquid formulation to choose the appropriate one for the plastic bottle.

B. If the liquid surface can reach a horizontal level quickly but has slight accumulation traces on the surface, the spray effect of a spray pump needs to be verified; other lotion pump models, treatment pump designs, and derived pumps can all be used.

C. If the liquid surface takes 1–2 seconds to reach a horizontal level and shows obvious accumulation traces, a lotion pump or treatment pump with strong suction and strong spring force must be selected. High-viscosity pumps are preferred, followed by the use of vacuum flask/bottle packaging.

D. If the liquid surface shows obvious accumulation traces and cannot reach a horizontal level within a short period, even high-viscosity pumps need to be verified. Vacuum flask/bottle packaging should be prioritized, or cap packaging should be selected for the cream bottle.

E. If the beaker filled with the liquid content is inverted and the liquid cannot pour out within a short period, only vacuum flasks, or other packaging forms such as caps, tubes, and a wide-mouth cream bottle, can be used.

03 Selection Based on the Compatibility Between Lotion Pump or Treatment Pump Raw Materials and the Content

The finished plastic bottle or cream bottle product must be able to pass the compatibility test. The finished product that has already dispensed liquid is placed in a high-temperature chamber for 7 days. After removal, it is disassembled and inspected. It is considered qualified if the components of the lotion pump or treatment pump show no cracking, rusting, or deformation, and the liquid shows no discoloration or odor change.

04 Selection Based on the Range of Discharge Output

Before a product is launched on the market, there is generally a consumer survey phase, which basically yields a preliminary recommended usage amount. Based on this usage amount, the specification of the lotion pump or treatment pump can be selected accordingly, or the recommended usage amount can be reached by a whole number of pump strokes.

Recommended Usage Amount = (1 - 2) * Discharge Output

05 Selection Based on the Final Packaging Form

Once the packaging capacity of the plastic bottle or cream bottle is confirmed, the lotion pump or treatment pump specification is selected based on the size of the packaging capacity combined with the estimated number of uses. Generally, the number of uses for a single package is 100 to 300 times.